This invention relates to apparatus for the automatic discharge of deodorant in toilet areas.

Objectionable odour in toilet facilities, both public and domestic, is acknowledged as a universal problem and much ingenuity has been expended in seeking its amelioration. In the operation of public area toilet facilities, it is common for ventilation or deodorant means of some form to be provided for the purpose. A long-used, passive-release deodorant system comprises one or more small blocks of a volatile solid compound, such as paradichlorobenzene or a number of ammonium quaternary compounds, which are placed in toilet areas and allowed to slowly evaporate to provide a deodorant effect. While inexpensive, such solid deodorant compounds have fallen into disfavour as a result of then- respiratory irritant effects and the unresolved possibility that they may be human carcinogens. A commonly used, active-release deodorant system comprises one or more aerosol cans of liquid deodorant from which short atomised discharges are made automatically, on a regular, time-related basis, or irregularly triggered by an act of toilet users. Such irregular, non-automatic deodorant discharges may be triggered by the change in water pressure in a flush pipe due to flushing of a toilet or urinal, by the opening or closing of a toilet door, by pressure upon a toilet seat, or the like. Such aerosol-based deodorant systems and similar systems which automatically meter sanitising deodorant compounds into toilet cistern flush pipes normally require professional installation. They are therefore relatively expensive and their use is confined more or less exclusively to public toilet facilities, hi domestic toilet facilities, a passive-release deodorant system commonly comprises one or more blocks of solid or gel, volatile, deodorant material contained in suitable housings and fixed to the exterior surface of a toilet cistern or to a toilet cubicle wall adjacent a toilet bowl. The deodorant material evaporates slowly, imparting a deodorant

effect which is not regulated or controlled, and are of limited effect against the intense, immediate and localised odours which may result from toilet use. Another form of passive-release deodorant system comprises a reservoir of a liquid deodorant material or a block of slowly soluble solid deodorant material placed within a toilet cistern. The deodorant material mixes with or dissolves into the toilet flush water and, through turbulent discharge of the flush water into the toilet pan, is released into the air in and around the toilet pan, imparting a deodorant effect. To provide an additional visual effect, it is usual for a colorant to be added to the deodorant material. Blocks of similar solid deodorant material are commonly suspended in suitable housings from toilet bowl rims and are progressively dissolved by contact with toilet flush water flows. Such deodorant means are also of limited effect against the intense, immediate and localised odours which may result from toilet use. A third form of passive-release deodorant system comprises a reservoir of a liquid deodorant material which is plugged into a mains electric power point, a small degree of electrical heating being employed to slowly vaporise the deodorant material to provide a deodorant effect. While inexpensive, such passive-release deodorant systems provide a sustained, but generally low- level deodorant effect and are relatively ineffective against intense, immediate and localised odours which may result from toilet use. Use is commonly made in domestic toilets of hand-held aerosol canisters from which deodorant is discharged as required by toilet users. The need for such deodorant discharges may be overlooked by toilet users and, where they are in fact made, are sometimes excessive, causing a nuisance in areas adjoining a toilet. Such hand-held aerosol canisters are frequently unsightly and inconvenient to store in a toilet cubicle and various means of concealment, typically talcing the form of dolphins, dolls and the like, have been used to accommodate them. In embodiments of the type taught by Miller et al in US 5,862,960 and Holyfield in US 6,505,759, the aerosol canister is contained within a housing and deodorant is discharged by manually depressing a push pad or pivoting cover associated with the

housing. Methods have been devised for the discharge of deodorant into toilet areas, using mechanical or electrical pumping, displacement of air during cistern refilling or the mechanical or electrical initiation of a discharge from an aerosol canister. Examples of the first method are those taught by Rosenkrantz & Rosenkrantz in US 4,056,228, Muderlak & Shieh in US 5,249,718. Examples of the second method are those taught by Lindauer in US 4,168,550, 4,209,863, 4,209,864 and 4,212,089. Examples of the third method are those taught by Church in US 4,358,860, Gangnath & Tudor in US 4,625,342, Martin & Batt in US 5,675,845, Percher in US 6,785,911 , Krvavica, Krvavica & Bluemel in US 6,282,732, Haygreen in US 6,694,536 and Cain in US 5,862,532. Active deodorant discharge devices for use in toilets and which require no installation are known. A partial example is the Glade Spin-Fresh® product, previously manufactured by S C Johnson & Son, Inc, which takes the form of an air freshener reservoir replacing the core tube roller of a toilet paper dispenser. When the air freshener reservoir is rotated by a user in withdrawing toilet paper from the toilet paper dispenser, air freshener is released, the volume being proportional to toilet paper use and thus not specifically metered. A similar device is that taught by He, Triplett & Pappalardo in US 6,688,551. Devices in which functions are triggered by sound are known. A toilet servicing device utilising this operating principle is that taught by Ehrensperger & Meier in US 6,098,211. In this device, a suitable microphone is positioned adjacent a toilet bowl and, when the elevated sound level of toilet flushing is detected, the toilet seat is automatically cleaned and odours evacuated via a ventilator. Such a system requires installation by a suitably qualified technician, hi a system taught by Contadini and Dean in US 6,347,414, one or more detectors taking a variety of forms and provided at the entry to a toilet facility count events (door movements, person movements and the like) or detect vapour, odour, smell or fragrance and, when certain criteria are met, trigger one or sanitisation, deodorisation or disinfection functions. In another device taught by Borut, Sharma, Hubmami & Prayne in US

6,644,507, time-based discharges of air freshening substance are made from an aerosol canister in a self-contained unit, the frequency of discharge being automatically regulated by reference to the ambient light level around the unit — increased when the light level is higher and reduced when lower. While all of the inventions cited are, to some degree or other, capable of fulfilling their intended function - to deliver atomised or vaporous deodorant into the air around a toilet - many require installation by a tradesperson and therefore have a relatively high installed cost. Practically speaking, many could only be installed in toilet cisterns at the time of manufacture. Some require an operating or triggering mechanism on the exterior of a toilet cistern which may be unsightly. Many have poor ability to regulate the timing, quantity and/or duration of deodorant discharges, factors important where deodorisation of toilet cubicles is to be performed. The object of the present invention is to provide a self-contained device incorporating a replaceable pressurised aerosol canister contained within a compact enclosure of attractive design, which device and enclosure may be readily attached to the exterior surface of a toilet cistern by an unskilled person to automatically and reliably discharge a metered discharge of atomised deodorant from the aerosol canister into the air adjacent the toilet after each toilet use event, as defined by flushing of the toilet cistern.

According to the present invention, an automatic aerosol deodorant discharge unit is provided comprising a frame which is readily attachable to the exterior surface of a toilet cistern with adhesive attachment pads; aerosol canister with support and securing means; discharging mechanism; one or more batteries; microphone; control unit and internal connections, all covered by a suitable cover of attractive design which is readily removable and replaceable. To install the deodorant discharge unit on the exterior surface of a toilet cistern, the cover is removed and, with batteries and aerosol canister absent, the orientation of said adhesive attachment pads is adjusted to more or less conform to the exterior surface of the toilet

cistern (where suitable adjustment means are provided). Protective covers are left in place on said adhesive attachment pads while their said orientation adjustment is made. When the orientation of said adhesive attachment pads is suitably adjusted, said protective covers are stripped from said pads and said pads are pressed firmly against the exterior surface of said toilet cistern in the mounting position required. Said adhesive attachment pads are made resilient to better conform to the exterior surface of said toilet cistern and, once in firm contact, bond strongly and more or less permanently to said cistern exterior surface. Attachment of said frame to said exterior surface of said toilet cistern urges said microphone into contact with the cistern exterior surface, in which position it is maintained by the urging of a suitable spring. The aerosol canister and batteries are then installed, the unit is turned on and the cover replaced. Thereafter, the unit monitors the sound level within said toilet cistern in a manner minimising current draw from the batteries. Whenever the toilet is flushed, a substantial rise in sound level within the cistern above ambient is detected by the microphone and communicated to the control unit. After verifying a sustained sound level rise, the control unit initiates operation of the discharging mechanism, thereby releasing a discharge of atomised deodorant of controlled duration from the aerosol canister into the air around the toilet. The control unit also monitors battery condition and the contents of the aerosol canister and generates suitable warnings if either is approaching a predetermined minimum state.

The various aspects of the present invention will be more readily understood by reference to the following description of preferred embodiments given in relation to the accompanying drawings in which:

Figure 1 is a partial front view of one embodiment of the present invention with cover, batteries and discharging mechanism deleted for clarity; Figure 2 is a partial side view of the embodiment of the present invention depicted at Figure 1 with the nearer half of the cover and the discharging mechanism deleted for clarity;

Figure 3 is an end view of attachment provisions of the embodiment of the present invention depicted at Figure 1 ;

Figure 4 is a partial view of the upper end of the embodiment of the present invention depicted at Figure 1 with the upper part of the cover and batteries deleted for clarity;

Figure 5 is a partial side view of the lower part of the embodiment of the present invention depicted at Figure 1 with the nearer half of the cover deleted and the discharging mechanism depicted in lay-out form; Figure 6 is a partial front view of the lower part of the embodiment of the present invention depicted at Figure 1 showing the discharging mechanism only;

Figure 7 is a side view of electrical contact provisions of the embodiment of the present invention depicted at Figure 6; Figure 8 is a partial side view of the upper part of an alternative embodiment of present invention depicted at Figure 1 with the nearer half of the cover deleted to show warning light provisions;

Figure 9 is a partial view from above of the embodiment of the present invention depicted at Figure 8 with the upper part of the cover deleted to show the warning light provisions;

Figure 10 is a schematic diagram of a typical electronic control system of the present invention;

Figure 11 is a longitudinal cross-sectional view of an alternative embodiment of the lower part of the present invention, including the discharging mechanism;

Figure 12 is a transverse cross-sectional view on A-A of the embodiment depicted at Figure 11 ;

Figure 13 is a partial longitudinal cross-sectional view of the upper part of a typical embodiment of the present invention;

Figure 14 is a longitudinal cross-sectional view of a typical planetary reduction gear system employed in alternative

embodiments of the present invention;

Figure 15 is a longitudinal cross-sectional view of the lower part of another alternative embodiment of the present invention, including the discharging mechanism; Figure 16a is a partial transverse cross-sectional view through a mid part of a typical embodiment of the present invention;

Figure 16b is a partial transverse cross-sectional view through a mid part of another typical embodiment of the present invention;

Figure 17 is a partial longitudinal cross-sectional view of the lower part of another alternative embodiment of the present invention, including the discharging mechanism;

Figure 18 is a transverse cross-sectional view of means of attaching one embodiment of the cover of the present invention;

Figure 19 is a partial transverse cross-sectional view of the edge of one embodiment of the cover of the present invention;

Figure 20 is a transverse cross-sectional view on B-B of the embodiment depicted at Figure 11 ; Figure 21 is a partial longitudinal cross-sectional view of the lower part of another alternative embodiment of the present invention, including the discharging mechanism;

Figure 22 is a frontal view of an alternative embodiment of the frame of the present invention; Figure 23 is a longitudinal cross-sectional view of the lower part of the embodiment of the present invention as depicted at Figure 11, but with minor modifications;

Figure 24 is a partial view from above of the embodiment depicted at Figure 23; Figure 25 is a transverse cross-sectional view through the embodiment depicted at Figure 22, but with minor modifications; Figure 26 is a partial frontal view of the embodiment

depicted at Figure 25;

Figure 27 is a partial longitudinal cross-sectional view of an alternative embodiment in which the position of said aerosol canister is fixed; Figure 28 is a transverse cross-sectional view of guide means depicted in Figure 27;

Figure 29 is a view from above of the embodiment depicted in Figure 27;

Figure 30 is a partial transverse cross-sectional view of an alternative embodiment in which the control unit circuit board of the present invention is mounted on pegs;

Figure 31 is a view from above of the embodiment depicted in Figure 37;

Figure 32 is a transverse cross-sectional view of the battery holder described in relation to Figure 22;

Figure 33 is a transverse cross-sectional view of an alternative embodiment in which switches associated with the control unit circuit board of the present invention are supported from the frame back plate of the present invention; Figure 34 is a transverse cross-sectional view of an alternative embodiment in which said switches are supported from said control unit circuit board;

Figure 35 is a transverse cross-sectional view of an alternative embodiment in which said switches are supported from side panels fixed to said frame back plate;

Figure 36 is a transverse cross-sectional view of an alternative embodiment of the guide means depicted at Figure 28;

Figure 37 is a longitudinal cross-sectional view of another alternative embodiment in which the position of said aerosol canister is fixed;

Figure 38 is schematic operational sequence diagram of a typical embodiment of the present invention;

Figure 39 is a continuation of the operational sequence depicted at Figure 38;

Figure 40 is a continuation of the operational sequence depicted at Figure 39; Figure 41 is a continuation of the operational sequence depicted at Figure 40;

With reference to Figures 1, 2, 3 and 4, an automatic aerosol deodorant discharge unit is made with a frame comprising transverse upper and lower members 1, 3 joined by vertical member 2. The outer ends of said transverse frame members are joined by convoluted sections 9 to attachment panels 10 provided on their outer surfaces with resilient adhesive attachment pads 4, the sticky surfaces of which are initially covered by strippable protective pieces (not shown). Said convoluted sections permit the ready bending adjustment of the orientation of said attachment panels. Said frame is attached to the exterior surface 5 a toilet cistern by first bending said attachment panels at said convoluted sections to more or less conform to the local shape of said exterior surface of said cistern in the position selected, then removing said strippable protective pieces and pressing said adhesive attachment pads firmly against said exterior surface of said cistern. Said adhesive pads are made resilient to better conform to the shape of said exterior surface of said cistern and, once in firm contact, bond strongly and more or less permanently. In the preferred embodiment, said frame is made from a suitable light, stiff metal material and is optionally provided with ribbing and/or edge flanges to stiffen its said transverse and vertical members. Vertical member 2 is provided with joggles at 11, 12 to create a raised central part beneath which is accommodated control unit circuit board 13 supported from said raised central part by short pillars (not shown) made from a suitable dielectric material. Supporting tray 7 and spring retaining clips 8 are fixed to said raised central part, said spring retaining clips retaining aerosol canister 6 in place with its base accommodated in said supporting tray. In the preferred embodiment, said spring retaining clips and said discharging

mechanism tray are made from a suitable sheet metal material or moulded from a suitable polymer material. A discharging mechanism (depicted in

Figures 5 and 6) is accommodated in discharging mechanism tray 14 fixed to lower transverse member 3. The fixed part of hinge 15 is fixed to upper transverse member 1 and its moving part is fixed to discharge fork 16.

Discharge nozzle 21 of aerosol canister 6 passes up through slot 22 of said discharge fork and areas of said discharge fork immediately adjacent said slot bear upon flange 20 formed at the lower end of said discharge nozzle.

Guide channels 23, 24 provided at the outer ends of transverse members 1, 3 slidingly accommodate locating rails (depicted as 25 in Figures 4 and 9) formed on the side inner surfaces of cover 26. The inner surfaces of said guide channels and the outer surfaces of said locating rails are provided with a plurality of complementary, blunt, symmetrical serrations (not shown) which co-operate to provide a positive frictional attachment of said locating rails within said guide channels, thereby retaining said cover on said aerosol deodorant discharge unit. The length of travel of said locating rails within said guide channels is such that, regardless of said bending adjustment of attachment panels 10, said cover is able to be pushed fully inwards with its inner edges positioned more or less flush with the exterior surface of said toilet cistern and retained in that position by said frictional attachment. A light outwardly directed force applied to said cover is sufficient to overcome said frictional attachment between said locating rails and said guide channels, permitting said cover to be pulled off and removed. Light leaf spring 18 is fixed in a more or less medial position to said circuit board and supports at its free outer end microphone 19. Said microphone is connected to the circuits of said circuit board by suitable conductors (not shown). The shape of said leaf spring is such that, when said automatic aerosol deodorant discharge unit is fixed in place on exterior surface 5 of said toilet cistern, said microphone is urged into and maintained in continuous contact with said cistern exterior surface. Aperture 27 is provided in the upper part of cover 26 and is made with an approximate diameter in the range of two to ten

times the diameter of discharge nozzle 21. Said aperture is centred over said discharge nozzle and is made elongated to accommodate deeper or shallower engagement of said locating rails in said guide channels. Typical positions of batteries are depicted in broken line as 28, 29, in the preferred embodiment said batteries being accommodated in battery holders made from a suitable polymer material and of a type well known in the art. Said battery holders are fixed, as appropriate, to either side of vertical member 2 and connected to said circuit board by suitable conductors (not shown). Suitable holes 30 are provided in the outer ends of discharge fork 16 to permit the attachment of wires (depicted as 32 in Figure 5) connecting said discharging mechanism (depicted in Figures 5 and 6) to said discharge fork.

With reference to Figures 4, 5, 6 and 7, said automatic aerosol deodorant discharge unit has an aerosol canister 6 maintained within it in a fixed position, the discharge valve in nozzle 21 of said canister being operated by a suitable discharging mechanism (depicted in Figures 5 and 6). In this embodiment, the arms of discharge fork 16 are connected to cam arms 31 forming part of a discharging mechanism by wires 32. The upper ends of said wires (not shown) pass up through holes 30 in said discharge fork arms and are secured in place by their being formed into suitable terminal formations or by suitable slugs (not shown) being crimped onto them. The lower ends of said wires are joggled and engage said cam arms by passing through suitable holes 34 in them. Said cam arms are connected at their inner ends in fixed relationship, in the preferred embodiment by their being fixed in parallel to torque tube 45. Said torque tube is pivotally supported on shaft 43 turning in suitable bearings formed in supporting members 44. hi an alternative embodiment, said cam arms and an inner transverse joining member are all formed from a single piece and supported in the manner described. Cams 42 are fixed to the outer ends of shaft 40 and co-operate with cam followers 57 formed in an appropriate position in cam arms 31. A light spring (not shown) is provided to urge said cam arms towards their upward positions. Rotation

of said cams causes the free end of said cam arms to rise and fall, drawing wires 32 downwardly and urging the shoulders of slot 22 in discharge fork 16 to bear downwardly against flange 20 of discharge nozzle 21 of aerosol canister 6, thereby triggering a discharge of atomised deodorant from said discharge nozzle. Electric motor 35 is fixed to supporting member 46 and drives in rotation first small gear 36. Said first small gear engages and drives in rotation first large gear 37 which is directly coupled to second small gear 38. Said second small gear engages and drives in rotation second large gear 39 which turns shaft 40. Said first small gear turns with electric motor shaft 58 which runs in a suitable bearing provided in supporting member 48. Said first large and second small gears turn with shaft 59 which runs in suitable bearings provided in supporting members 48, 49. Shaft 40 turns in suitable bearings provided in supporting members 50, 49, 47. Electric motor 35 is connected by suitable conductors (not shown) to said control unit circuit board and to said batteries via contacts 52, 54.

With reference also to Figure 7, contact cam wheel 41 turns with shaft 40 and contact cam follower 55 urges said contacts into conducting co-operation whenever said contact cam follower passes out of recess 56 formed in the periphery of said contact cam wheel. In operation, said control unit circuit board connects electric motor 35 briefly to said batteries, causing said contact cam wheel to rotate and said contact cam follower to pass out of recess 56, thereby urging contacts 52, 54 into conducting co-operation and connecting said electric motor directly to said batteries. Following said brief connection, said control unit circuit board terminates the direct flow of current to said electric motor which continues in operation supplied with current from said batteries via contacts 52, 54. When said contact cam wheel has completed a full revolution, cam follower 55 re-enters recess 56, separating said contacts, breaking the circuit to said batteries and thereby de-activating said electric motor. Said recess is made with sufficient circumferential length to ensure that said cam follower remains within said recess if any minor run-on of said

electric motor occurs following its de-activation. In an alternative embodiment, the apparatus depicted in Figure 7 is deleted and electric motor 35 is powered only from said control unit. In this embodiment, said electric motor is powered for a controlled time period determined by said control unit to provide a deodorant discharge of the desired duration. In the preferred embodiment, where a short, medium or long discharge of said deodorant is desired, said electric motor is operated, respectively, at high, medium and low speed. In an alternative embodiment, said cams are turned, respectively, once, twice or three times to achieve an equivalent effect.

With reference to Figures 8 and 9, a warning apparatus is provided to display a visual alert whenever the charge level of said batteries is approaching a predetermined minimum or the contents of said aerosol canister have been depleted to a predetermined minimum. In this embodiment, light emitting diodes 60, 61 supported from upper transverse frame member 1 by stalks 70, 71 are connected to said control unit by suitable conductors (not shown). Supporting bars 66, 61, formed on and projecting inwardly from locating rails 25, support at their inner ends cylindrical light emitting diode housings 64, 65 made from a material impervious to light. Flexible light guides 62, 63 pass from said light emitting diode housings to terminal moulding 68 fixed to the outer part of cover 26 in a position opposed to mounting surface 5. Said light guides take the form of long, flexible cylinders of a suitable clear polymer material and their outer ends project slightly beyond said terminal moulding. The axial length of said light emitting diode housings is such that, regardless of the depth of engagement of said locating rails with guide channels 23, 24, said light emitting diodes do not contact said light emitting diode housings. When an appropriate value is detected or calculated by said control unit, current is intermittently is supplied to the appropriate said light emitting diode and the light thereby produced passes along the appropriate said light guide causing its outer end to be illuminated to provide said warning. In an alternative embodiment (not

shown), said light emitting diodes are supported on said stalks fixed to either side of upper transverse frame member 1, said stalks being directed upwardly towards the upper surface of cover 26. Buttons of a suitable transparent polymer material are provided on the upper, outer surface of said cover and a short extension of each passes inwardly through the thickness of said cover to terminate adjacent the positions of said light emitting diodes when said cover is in its normally installed position. Light emitted by a said light emitting diode passes up through said short extension causing its said button to be illuminated. A medially positioned, downwardly projecting light blocking panel of suitable dimensions formed on the upper, inner surface of said cover passes between said two light emitting diodes and prevents light from one producing a spurious illumination (and warning) at said button of the other. In the preferred embodiment, the projecting ends of said light guides and said buttons of said transparent polymer material are coloured differently to better permit the nature of a warning to be identified.

With reference to Figure 10, all functions of said deodorant discharge unit are controlled by a control unit 72 formed on circuit board 13. Said control unit is based upon a microprocessor having volatile and non-volatile memories. Powered from batteries 28, 29 through suitable conductors 79, said microprocessor processes sound level data received from microphone 19 through suitable conductors 80, battery voltage data from said batteries and deodorant discharge data generated internally and, as appropriate, triggers a deodorant discharge or generates said visual warnings in relation to a low battery condition or aerosol canister contents depletion. In the preferred embodiment, said microprocessor takes the form of a programmable integrated circuit (PIC) which is operated to minimise current draw. Such PICs may have an approximate current draw of only one microamp in their resting state and one milliamp while processing. Software loaded into said PIC directs said PIC to read the sound level detected by said microphone on a regular basis and to compare the detected level with a reference sound level. When a sharp increase in

sound level caused by toilet flushing is transmitted through suitable conductors 80 to said control unit, said control unit initiates operation of said discharging mechanism through suitable conductors 75 to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period. In the preferred embodiment, said software directs said control unit to capture a reference sound level reading from said microphone and hold it in memory. A successive sequence of sound level readings is compared to this reference reading and, should an increase in sound level be detected, discharge of said deodorant is initiated as previously described. In the preferred embodiment, the number of readings in said sequence is 5, of a duration of 0.5 second and taken at intervals of 5 seconds. If no increase in sound level is detected, the fifth successive reading in said sequence is then captured in memory and the process repeated. In alternative embodiments, said sequence of sound level readings numbers between one and 100, of a duration of between 0.1 and 5 seconds and at intervals of between 0.1 of a second and 100 seconds. In other alternative embodiments, any other suitable type of microprocessor is employed. In another alternative embodiment, successive sound level readings are averaged and stored in memory as a reference average sound level datum which is continuously updated. Each sound level reading is then compared to said reference average sound level datum and, if an increase in sound level over said reference average sound level datum is detected, discharge of said deodorant is initiated as described. In the preferred embodiment, when an elevated sound level is detected, a sequence of sound samplings is immediately taken to confirm that said elevated sound level is sustained and is not a short-duration sound event such as, for example, slamming of the toilet lid. In the preferred embodiment, sound samplings in said sequence of sound samplings number between one and 100, of a duration of 0.1 to 5 seconds and at intervals of between 0.1 of a second and 10 seconds. In the preferred embodiment, at commencement of operation of said automatic aerosol deodorant discharge unit, said initiation of discharge of said

deodorant is suppressed until a confirmed initial reference sound level reading is taken or a reference average sound level datum is established. Also in the preferred embodiment, during normal operation, said initiation of discharge of said deodorant is suppressed for a predetermined period following a preceding deodorant discharge or until said elevated sound level in said cistern has subsided. In the preferred embodiment, to extend battery life, when said control unit is not accepting or processing data, its microprocessor reverts to its resting state. In an alternative embodiment, said control unit suppresses all of the signal received by said microphone during a said sound sampling excepting that part characteristic of the hissing sound of pressurised water passing through a valve, hi this way, said control unit is better able to discriminate the sound of cistern filling from other possible sounds or background noise. To avoid the generation of conflicting sound, said control system optionally suppresses said sound sampling process while said deodorant discharge process is in train. In an alternative embodiment (not shown), an immediate discharge button is provided on said automatic aerosol deodorant discharge unit, the pressing of which effectively signals to said control unit that a confirmed increase in sound level has been detected, immediately triggering a discharge of deodorant of a duration or quantity as selected in said unit. Said button is fixed to any suitable part of said unit and, in the preferred embodiment, is coloured differently from said cover and projects through a suitable aperture in it. In the preferred embodiment, an internal switch is provided (beneath said cover) to disable said immediate discharge button, thereby preventing its misuse by children.

In the preferred embodiment, said control unit incorporates battery condition sensing means, data from said sensing means being processed and causing generation of said visual warning (or optional audible warning) if the voltage of said batteries falls below a predetermined value. In the preferred embodiment, said control unit also counts either long, medium or short discharges of said atomised deodorant, said discharge data being processed and causing generation of said visual warning if the

calculated residual deodorant contents fall below a predetemuned value. Said residual contents value is expressed as a summed total of discharge quantity units counted and stored in memory by said control unit. Such sensing and warning circuitry are well known in the art. Also in the preferred embodiment, a suitable switch 73 is provided to permit the user to set the operational mode of said deodorant discharge unit. In the preferred embodiment, said switches are of the three-position type, allowing for selection of long, medium or short discharges of deodorant, depending upon the preference of the user for a greater or lesser deodorant effect. Said switch is optionally of the sliding type, providing universally- variable adjustment. Also in the preferred embodiment, an on-off switch 74 is provided to permit said deodorant discharge unit to be switched on and off and an optional reset switch (or button) 78 is provided to permit resetting of the memory of said microprocessor when a new aerosol canister is installed in said automatic aerosol deodorant discharge unit. Obviously, said memory may be reset by turning said unit off, and then on again using said on-off switch. In the preferred embodiment, said switches are exposed for access by removal of said aerosol canister from said spring retaining clips. Said visual warnings are displayed using the apparatus described in relation to Figures 8 and 9, said apparatus being connected to said control unit by suitable conductors 76, 77. Said visual warnings take the form of brief illuminations of said light emitting diodes, ranging in duration from 0.1 to 0.5 of a second at time intervals ranging from 10 seconds to 30 minutes, said time intervals preferably progressively reducing as the detected deficiency persists. In an alternative embodiment, suitable devices (not shown) are provided to generate audible warnings if the voltage of said batteries falls below a predetermined value or if said calculated residual deodorant contents fall below a predetermined value. Said audible warnings take the form of brief tones ranging in duration from 0.1 to 0.5 of a second at time intervals ranging from 10 seconds to 30 minutes, said time intervals preferably progressively reducing as the detected deficiency persists. Said audible

warnings are supplementary to or alternative to said visual warnings. In the preferred embodiment, said audible warnings are generated by a miniature piezo-electric tone generator and a suitable aperture is provided in said cover to permit egress of sound. In all embodiments of said automatic aerosol deodorant discharge unit described herein in which said aerosol canister is elevated by the action of said electric motor, said control unit incorporates electronic means to detect stalling of said motor. Such means are well known in the ait and an example is that taught by Muderlak & Sheih in US 5,908,140. In an alternative embodiment (not shown), said control unit measures the time duration of cistern refilling and determines from acquired and stored elevated noise duration data whether said cistern has undergone a short or long flush. Depending upon the type of flush duration determined (half flush or full flush), said control unit generates, respectively, a short or long discharge of deodorant.

In said process of calculating said residual deodorant contents, said control unit counts a short said discharge of deodorant as 1 discharge quantity unit, a medium said discharge as 2 discharge quantity units and a long said discharge as 3 discharge quantity units and stores the sum of all said discharge quantity units in memory until said automatic aerosol deodorant discharge unit is turned off or said re-set button is pressed. A warning is provided when said sum of all discharge quantity units exceeds a predetermined maximum value.

The arrangement of said microphone is such that it is substantially protected from airborne sound and receives sound inputs almost totally via conduction through the wall of said cistern. In an alternative embodiment (not shown), excepting its contact surface with said cistern, said microphone is surrounded by suitable material to suppress airborne sound. With reference again to Figures 1 and 2, in another alternative embodiment, said frame comprising transverse upper and lower members

1, 3 joined by vertical member 2 is deleted and replaced by a flexible plate (not shown) moulded from a suitable polymer material and provided on its

inner surface with a plurality of said adhesive attachment pads (not shown). Said flexible plate is provided with slits (not shown) of more or less vertical and horizontal orientation to permit its flexing to accommodate a compound curved surface. Said flexible plate optionally incorporates a raised vertical part analogous to vertical member 2 (as depicted in Figure 2) beneath which circuit board 13 is accommodated. Said raised vertical part is optionally moulded integrally with said flexible plate, or made separately from sheet metal material or a suitable polymer material and attached to said flexible plate. Clips 8, trays 7, 14 and said battery holders are also optionally moulded integrally with said flexible plate or made as separate pieces from sheet metal or moulded from a suitable polymer material and attached to said flexible plate.

With reference to Figures 11, 12 and 20, in an alternative embodiment, said automatic aerosol deodorant discharge unit has an aerosol canister 6 moveably supported within it, the discharge valve of said canister (depicted as 21 in Figure 13) being operated by the bodily displacement of said canister along its longitudinal axis by the mechanism described hereunder to urge said discharge valve into abutment with a fixed contact member (depicted as 111 in Figure 13). In this embodiment, said aerosol canister is supported on canister platform 81, a raised edge 82 of said platform serving to retain said canister in place. Said platform is, in turn, supported in its rest position on supporting member 83 which typically comprises curved peripheral element 84, pillar bushes 85, motor housing 86, radially-arranged stiffening elements 87, straight side elements 106 and straight fixing element 88. In the preferred embodiment, said fixing element is preferably extended downwardly to provide greater support and a larger attachment surface and is bonded to frame back plate 89 or fixed to it with suitable fastenings (not shown). Suitable ribs 90 extending more or less along the full length of the side edges of said fixing element engage complementary recesses 91 provided in the side edges of said frame back plate for the purpose of accurately locating said supporting member. In the preferred embodiment, frame back plate 89 is

fixed to the exterior surface 5 of a toilet cistern, or other surface as appropriate, by adhesive attachment pads (not shown) as described in relation to Figure 22. Said frame back plate is provided with side panels (not shown) fixed to its side edges, extending substantially along the length of said frame back plate and meeting above said discharge valve of said canister to form said fixed contact member. In the preferred embodiment, said side panels extend inwardly from said frame back plate to more or less meet said aerosol canister at its transverse diametral plane. Transversely-located canister support webs (position indicated in broken line as 93) are provided fixed to said frame back plate and said side panels, said webs having an exposed edge shape complementary to the exterior surface of said canister. Stiffening gussets (position indicated in broken line as 94) are optionally provided, bonded to said frame back plate and to lateral extensions (not shown) of side elements 106 of supporting member 83, passing outside of canister platform 81. In an alternative embodiment, said side elements of said supporting member are suitably bonded to said side panels.

Pillars 95, formed on or fixed to the underside of canister platform 81 extend downwardly through pillar bushes 85 with which they maintain a free, sliding relationship and are made sufficiently long to permit the desired elevation of canister platform 81. Suitable dry or greasy lubricant is optionally provided on the co-operating surfaces of said pillars and said pillar bushes. Said pillars are joined at their lower ends to the outer ends 96 of the arms of spider member 97 by bonding or by suitable fastenings 98. In an alternative embodiment (not shown), joining members in the form of complementary dowels and recesses are provided in said lower ends of said pillars and said outer ends of said arms of said spider, said complementary joining members being simply pressed together during assembly in frictional attachment. Such joining arrangement is satisfactory in that compressive forces always exist between said joined pails. Threaded nut 99 is moulded into or suitably fixed to the centre of said spider member and threaded rod 101 is screwably engaged with said

nut. Said threaded rod is rotationally driven by electric motor 100 through motor shaft 103. Said motor is accommodated within motor housing 86, bonded into position or retained by suitable fastenings. In an alternative embodiment (not shown), said motor is frictionally retained within said motor housing, a narrow flange extending substantially around the upper peripheiy of said motor being accommodated within a complementary recess formed in the upper edge of said motor housing and one or more detents provided in said flange engaging complementary lugs provided in said complementary recess. Such arrangement acts to positively restrain said motor against the downward forces generated by the co-operation of said threaded rod and said nut and against rotational displacement. Where required, a suitable thrust bearing 102 of said motor is accommodated within the thickness of canister platform 81 in suitable recess 104. hi the preferred embodiment, said thrust bearing takes the form of a miniature, angular-contact ball bearing or of a pair of suitably lubricated abutting plates, one supported from the housing of said motor in a fixed position and the other fixed to the end of and rotating with motor shaft 103. In alternative embodiments, said motor and said thrust bearing project above the upper surface of said canister platform, being accommodated within the concave base of said aerosol canister. Said thrust bearing supports axial loads applied to the shaft of said motor.

Operation of said motor in the appropriate rotational sense causes said threaded rod to be screwed into said nut, thereby causing said spider member to be elevated together with said pillars, said canister platform and said canister until the flange of said canister discharge valve (depicted as 20 in Figure 13) is urged into contact with said fixed contact member (depicted as 195 in Figure 22) to depress said discharge nozzle and unseat said aerosol canister discharge valve to effect a release of deodorant. Reversal of said motor restores said components to their rest positions. In the preferred embodiment, said motor takes the form of a compact, reversible, high-speed, permanent-magnet-type, reversible, direct current electric motor. Said threaded rod takes the form of a rod of diameter in

the range 2 to 10 millimetres with a thread pitch in the range 0.1 to 10 millimetres. Where said threaded rod has a larger pitch, a more powerful motor is necessarily employed and vice versa. In a typical example of the preferred embodiment, said threaded rod has a diameter of 6 millimetres and a thread pitch of 0.9 millimetres, 10 turns of said motor effecting a lift of 9 millimetres in said spider member. Smaller motors are optionally employed in conjunction with suitable reduction gear means (as depicted in Figure 14). In the preferred embodiment, suitable stops (not shown) are provided on said pillars to limit their displacement, said motor stalling when said stops abut the lower surfaces of pillar bushes 85. In the preferred embodiment, said stops take the form of collars of suitable length placed on said pillars.

Skirt 105 is formed integrally with and extending downwardly from curved peripheral element 84. The depth of said skirt is made sufficient to wholly or substantially conceal pillars 95 and spider member 97 and the typical position of its side edges is depicted as 107. hi alternative embodiments, the lateral extent of said skirt is limited to the general extent of curved peripheral element 84, said skirt being clipped, bonded or fastened with suitable fasteners to the lower edge of said curved peripheral element employed to support warning lights, switches and the like.

Frame back plate 89 extends downwardly from the lower edge of straight fixing element 88 and is provided with microphone access aperture 108. Leaf spring 18, supporting microphone 19 at its free end, is fixed to circuit board 13 and passes outwardly through slot 109 provided in said circuit board and aperture 108. One or more circuit board support pillars 110 are optionally provided on the lower edge of said frame back plate, hi the preferred embodiment, said circuit board is bonded to said straight fixing element 88 and pillars 110 or fixed to said parts by suitable fastenings. In an alternative embodiment, suitable pegs are provided on said straight fixing element or said frame back plate and said pillars, said pegs making a secure interference fit with suitable holes provided in said

circuit board when said circuit board is pressed over said pegs. Fixing of said automatic aerosol deodorant discharge unit to said exterior surface of said toilet cistern obviously acts to bring said microphone into contact with said exterior surfaces of said toilet cistern in which situation it is maintained by the urging of leaf spring 18. Such arrangement supports said circuit board clear of said exterior surface of said toilet cistern, thereby protecting it from the effects of condensation on said exterior surfaces. In an alternative embodiment, said circuit board is suitably treated to protect it and its components against the effects of moisture. Cover 26 is secured in place over the described components of said automatic aerosol deodorant discharge unit and retained in place by suitable securing means. One or more arcuate guide members 92 provided on the inner surface of said cover make light sliding contact with said aerosol canister and act to retain it in place on canister platform 81. hi the preferred embodiment, cover 26, canister platform 81, pillars 95, spider member 97, skirt 105, supporting member 83, frame back plate 89 (together with said side panels, said fixed contact member, gussets 94 and support webs 93) are all made by injection moulding from suitable polymer materials. With reference to Figure 13, aerosol canister 6 is retained in place on said canister platform by the light, sliding contact of one or more arcuate guide members 92 provided on the inner surface of cover 26. Discharge nozzle 21 of said aerosol canister passes up through slot 112 of fixed contact member 111. Gusset 113 formed on frame back plate 89 is optionally provided to buttress said fixed contact member. Elevation of said aerosol canister in the manner described results in areas of said fixed contact member immediately adjacent said slot bearing upon flange 20 formed at the lower end of said discharge nozzle, thereby depressing said discharge nozzle and unseating said canister discharge valve to effect a release of deodorant. Suitably shaped aperture 27 is provided in the upper part of cover 26 and is made with an approximate diameter in the range of two to ten times the diameter of discharge nozzle 21. Said aperture is

centred over said discharge nozzle and is optionally made elongated, with its major axis up to 50% greater than its minor axis, to accommodate deeper or shallower engagement of said cover as may be determined by the shaping of said exterior surfaces of said toilet cistern. With reference to Figure 14, in an embodiment in which the torque required from a motor to raise said aerosol canister is greater than its output, reduction gear means are employed. In the typical embodiment depicted, motor shaft 103 is fixed to first stage drive plate 117, said first stage drive plate being rotationally supported on an extension of said shaft running in bush or bearing 114 provided in the upper end of fixed pillar 115 formed on the free end of support arm 116 which is, in turn, fixed to the lower end of frame back plate 89. Suitable washer 125 is provided between said first stage drive plate and the upper end of said fixed pillar. First stage planetary gears 118 turn on shafts 122 fixed to second stage drive plate 127, with suitable washers 126 being provided between said gears and said second stage drive plate. Smaller gear bands 119 of said first stage planetary gears engage the gear band of internal gear 120 provided on the interior surface of ring 121 formed on the periphery of said first stage drive plate. Larger gear bands 123 of said first stage planetary gears engage the gear band of sun gear 124 provided on the exterior surface of fixed pillar 115. Said second stage drive plate is accurately and rotationally supported by planetary gears 118 engaged with their said gear bands turning on shafts 122. In an alternative embodiment (not shown), said second stage drive plate is rotationally supported by its inner surface 139 turning on a suitable bush pressed into a suitable position over gear band 124 of fixed pillar 115. Second stage planetary gears 128 turn on shafts 133 fixed to output plate 137 with suitable washers 134 being provided between said gears and said output plate. Smaller gear bands 129 of said second stage planetary gears engage the gear band of internal gear 130 provided on the interior surface of ring 131 formed on the peripheiy of said second stage drive plate. Larger gear bands 132 of said second stage planetary gears engage the gear band of

sun gear 124 provided on the exterior surface of fixed pillar 115. Said output plate turns on bearing 135, shoulder 136 of said output plate abutting the outer race of said bearing and shoulder 138 at the base of said fixed column abutting the inner race of said bearing. In the preferred embodiment said bearing takes the form of an angular contact ball bearing or of a pair of suitably lubricated abutting plates, one supported from said fixed column in a fixed position and the other fixed to and rotating with said output plate. Those well versed in the art will understand that each said reduction gear may optionally be made in one or two stages and that each said stage may readily be employed to provide a speed reduction of 10:1 with a commensurate torque increase. It will be understood also that the total speed reduction achieved by the two-stage reduction gear arrangement is given by the product of their two ratios. In the preferred embodiment, said components of said reduction gear assembly, excepting said shafts, said washers, said bush or bearing and said bearing, are made by injection moulding from suitable polymer materials. In an alternative embodiment in which it is desired to make said reduction gear more compact, components are made from suitable metal materials. In alternative embodiments, cylinder 140 formed on the periphery of said output plate is formed into a cam member (as depicted in Figure 17) or a nut member (as depicted in Figure 21) or other actuation device, rotational movement of which is employed to raise said aerosol canister. Downward force generated by said screw, cam or the like in elevating said aerosol canister is transmitted via bearing 135 and support arm 116 to a suitable downward extension of straight fixing element 88 or frame back plate 89.

With reference to Figure 15, in an alternative embodiment, motor 100 is mounted as previously described. Reduction gear 144 is driven by said motor through shaft 103 and the output of said reduction gear is transmitted to spider member 141 rotationally supported on bearing 142. Said bearing is supported on the free end of support arm 116, said support arm being fixed to a suitable downward extension of straight fixing element 88. The configuration of said reduction gear is such that only a

partial rotation of said spider member occurs during a normal run time of said motor and suitable stops (not shown) are provided to limit said rotational displacement of said spider member. Pillars 146, formed on or fixed to the underside of canister platform 81, extend downwardly through pillar bushes 85 with which they maintain a free, sliding relationship and are made sufficiently long to permit the required elevation of canister platform 81. Suitable sockets 147 are provided in the free ends of said pillars. Suitable dry or greasy lubricant is optionally provided on the cooperating surfaces of said pillars and said pillar bushes. Suitable sockets 148 are provided in the upper surface at the outer ends of the arms of spider member 141 and props 145 of suitable length are captured between the sockets of said pillar sockets and the sockets of said spider member arms. The ends of said props are made part-spherical to match the complementary shaping of said sockets and a suitable greasy or dry lubricant is provided in said sockets. In the rest position of said aerosol canister, said spider member is rotationally displaced in relation to said pillars to cause said props to adopt an oblique position. When said motor is actuated to drive said reduction gear through shaft 103, said spider member is rotationally displaced in relation to said pillars to bring it into contact with said stops, in which position said props have been brought to an upright position, more or less parallel to the longitudinal axis of said aerosol canister, thereby elevating canister platform 81 together with said canister and urging said flange of said nozzle against said fixed contact member, to depress said discharge nozzle and unseat said aerosol canister discharge valve to effect a release of deodorant.

Warning lights 150 in the form of suitable light emitting diodes are fixed to the exterior surface of skirt 105 and connected to said control unit circuit board by suitable conductors (not shown). Cover 26 is provided in the installed position adjacent said lights with panel 149 made from a material impervious to light. Said panel is provided on its inner surface with shallow tubular light shades 152, one said light shade substantially enclosing each said light, and with transparent, optionally coloured, lenses

passing through said panel and positioned collinear with said lights. When a warning is generated by said control unit by the illumination of a said light emitting diode, said light shades prevent the illumination of a said lens other than by the light emitting diode provided for that lens. Similarly, said light shades prevent the general internal illumination of said cover. Obviously, the lenses of said light emitting diodes may be simply extended to protrude through suitable apertures provided in said cover, hi the preferred embodiment, said light emitting diodes are fixed to said skirt with suitable clips. With reference to Figure 16a, aerosol canister is maintained in sliding contact with support webs 93 by wire retainer 158. Side panels 153 are provided with narrow channels 154 to accommodate the inner ends of said wire retainer clear of cover 26 (when it is in place) and said wire retainer is joggled outside the open, outer ends of said channels to bring it into closer contact with the exterior of said aerosol canister, hi an alternative embodiment, suitable spherical, barrel-shaped or cylindrical beads are provided on the parts of said wire retainer in contact with said aerosol canister to provide, effectively, bearing means which permit said aerosol canister to move more freely beneath said wire retainer, hi an alternative embodiment, said aerosol canister is retained in position by an elastic band secured to suitable hooks positioned on either side of said aerosol canister and passing across its outer exterior surface. In a further alternative embodiment, said aerosol canister is retained in place by a light strap of suitable material, one end of which is fastened to one said side panel and the other led across the outer exterior surface of said canister to be fastened to a suitable hook, Velcro-type attachment or the like provided on the other said side panel. Suitable apertures 161 are provided in said support webs, if required, to permit the feeding through of conductors. Rounded projections 159 provided on the inner exterior surfaces of said side panels adjacent frame back plate 89 engage complementary detents formed in the inner interior surfaces of said cover, co-operation of said projections and detents acting to secure said cover in place on said

automatic aerosol deodorant discharge unit whilst permitting it ready removal.

With reference to Figure 16b, recess 162 extending into the thickness of frame back plate 89 and side panel 153 is provided to accommodate typical dry cell-type batteries of cylindrical shape. Suitable contact fittings of the type well known in the art (not shown) are provided at the end positions of said cells to retain said cells in place and connect them to suitable conductors supplying current to said circuit board and said motor, hi an alternative embodiment, in which batteries having a larger diameter are to be accommodated, said frame back plate is made suitably wider and said support webs are laterally displaced to similarly laterally displace the location of said aerosol canister away from the battery accommodation area. In such arrangement, said batteries are effectively retained in position by said aerosol canister. With reference to Figure 17, in an alternative embodiment, said motor (not shown) is mounted as previously described. Reduction gear 144 is driven by said motor through shaft 103 and the output of said reduction gear is transmitted to cam member 163 rotationally supported on bearing 170. Said bearing is supported on the free end of support arm 116, said support arm being fixed to a suitable downward extension of said straight fixing element or the lower part of said frame back plate. The configuration of said reduction gear is such that only a partial rotation of said cam member occurs during a normal run time of said motor and suitable stops (not shown) are provided to limit said rotational displacement of said cam member. Pillars 165, formed on or fixed to the underside of canister platform 81 extend downwardly through pillar bushes 85 with which they maintain a free, sliding relationship. Suitable diy or greasy lubricant is optionally provided on the co-operating surfaces of said pillars and said pillar bushes. Said pillars are joined at their lower ends to stabilising ring 166 by bonding or by suitable fastenings. Suitable slots 167 are provided in the lower ends of said pillars and rollers turning on radially-arranged shafts 169 are accommodated within said slots, hi the

embodiment depicted, each of said rollers of said pillars bears upon differing parts of the cam ramp of said cam member and said pillars are therefore made in differing lengths appropriate to the proper support of said canister platform, Activation of said motor to drive said reduction gear through shaft 103 causes said cam member to be rotationally displaced into abutment with said stops, thereby elevating said rollers on said cam ramp. Elevating of said rollers raises said pillars, said canister platform and said aerosol canister, urging said flange of said discharge nozzle against said fixed contact member to depress said discharge nozzle and unseat said aerosol canister discharge valve to effect a release of deodorant. In an alternative embodiment, said cam member is made with a plurality of identical cam ramps - one for each said pillar, with all said pillars being of equal length. Switches 172 are provided fixed to skirt 105 and connected to said circuit board by suitable conductors (not shown). Said switches are optionally provided for the purposes of on/off function, selection of operational mode (deodorant discharge duration) and resetting of contents monitoring system when said aerosol canister is renewed. Said re-setting switch is optionally of the press-button type.

With reference to Figure 18, in an alternative embodiment cover 26 is made from a softly flexible polymer material with a thin inner edge 173 which moulds itself readily to accommodate any exterior surface shape of a said toilet cistern. A stiffening strip 181 of more or a less rigid material is fixed by bonding or fusing to the inner surface of each side of said cover extending more or less along the full length of the sides of said cover and sufficient distance in from edge 173 to not inhibit its free, mouldable accommodation. In appropriate locations, said stiffening strips are provided with one or more rows of upwardly directed serrations of a suitable pitch orientated parallel to frame back plate 89. Catches 176 are provided at their free ends with complementary* downwardly-directed serrations 182, said catches being pivotally supported on shafts 175 passing between pairs of parallel pivot support webs 174 formed adjacent the edges of said frame back plate in appropriate positions. Said catches

are provided at their bases with detents 183 and stop arms 177 and a knuckle 178 formed on the free end of a stiff leaf spring 179 is strongly urged into each said detent by said leaf spring. The ends of said leaf springs opposed to said knuckles are fixed to bosses 180 formed on said frame back plate adjacent said pivot support webs and the urging of said knuckles into said detents acts to prevent all but minor pivotal displacement of said catches when light forces are applied to them. When said cover is pushed into place over said catches, said catches yield slightly to permit their said serrations to first pass over and then to engage said complementary serrations of said stiffening strips, which engagement acts to positively retain said cover in place on said automatic aerosol deodorant discharge unit with thin edges 173 of said cover moulded to the exterior surface shape of said toilet cistern. When it is desired to remove said cover, moderate pressure is applied to its sides, deforming them inwardly and thereby causing said catches to be displaced inwardly, pivoting on said shafts to bring the free ends of stop arms 177 into contact with bosses 180, with said knuckles displaced from said detents. Disengagement of said complementary serrations of said stiffening strips and said catches frees said cover for removal. Before replacement of said cover, said catches are pivotally displaced outwardly to restore said knuckles to said detents and position said serrations of said catches to engage said serrations of said cover stiffening strips.

With reference to Figure 19, in an alternative embodiment cover 26 is made from a softly flexible polymer material with a thin edge 173 which moulds itself readily to accommodate any exterior surface shape of a said toilet cistern. In the preferred embodiment, said thin edge curvingly turns outwards through an angle of between 15° and 60°. With said automatic aerosol deodorant discharge unit fixed to the exterior surface 5 of said toilet cistern and said cover installed on said automatic aerosol deodorant discharge unit and secured in position using suitable attachment means, said thin edge is readily deflected to mould itself to closely accommodate the exterior surface shape of a said toilet cistern.

With reference to Figure 21, in an alternative embodiment, motor 100 is mounted as previously described. Reduction gear 192 (partially accommodated within nut member 185) is driven by said motor through shaft 103 and the output of said reduction gear is transmitted to said nut member rotationally supported on bearing 188. hi the preferred embodiment, said nut member is provided on its external circumferential surface with a coarse, multi-start thread (depicted in broken line as 186). Said bearing is supported on the free end of support arm 116, said support arm being fixed to a suitable downward extension of said straight fixing element or said frame back plate. The configuration of said reduction gear is such that only a partial rotation of said nut member occurs during a normal run time of said motor and suitable stops (not shown) are provided to limit said rotational displacement of said nut member. Pillars 184, formed on or fixed to the underside of canister platform 81 extend downwardly through pillar bushes 85 with which they maintain a free, sliding relationship and are made sufficiently long to permit the desired elevation of canister platform 81. Suitable dry or greasy lubricant is optionally provided on the co-operating surfaces of said pillars and said pillar bushes. Said pillars are joined at their lower ends to stabilising ring 187 by bonding or by suitable fastenings. Screw teeth 190 complementary to and engaging thread 186 are provided on the inner sides of the lower parts of said pillars, said screw teeth and threads being suitably lubricated. Activation of said motor to drive said reduction gear through shaft 103 causes said nut member to be rotationally displaced, thereby screwing said screw teeth axially past said nut member and elevating said pillars. Elevation of said pillars elevates said canister platform and said aerosol canister, urging said flange of said discharge nozzle against said fixed contact member to depress said discharge nozzle and unseat said aerosol canister discharge valve to effect a release of deodorant. In an alternative embodiment, said nut member is provided with a single-start thread of finer pitch and makes multiple turns to raise said pillars.

With reference to Figure 22, the structural part of said automatic aerosol deodorant discharge unit comprises frame back plate 89 to which are fixed side panels 153, canister support webs 93 and fixed contact member 195. Adhesive attachment pads 193 are provided in appropriate positions on the reverse surface of said frame back plate, including on two or more suitably located floating panels 196 formed in said frame back plate. Said floating panels are generally of the same thickness as said frame back plate, to the generality of which they are connected only by thin connecting straps 197, said connecting straps having sufficient flexibility to permit the ready orientation of said floating panels to accommodate the local shape of said exterior surfaces of said toilet cistern. To install said frame back plate on the exterior surface of said toilet cistern, strippable protective pieces are removed from said adhesive attachment pads which are then pressed firmly against said exterior surface of said cistern to ensure their proper adhesion. Pressure is applied separately to said floating panels to ensure the proper adhesion of their adhesive attachment pads, said floating panels orientating themselves as required on their said connecting straps. Narrow channels 154 are provided in said side panels in appropriate positions to accommodate wire retainers (depicted as 158 in Figure 16a) to secure said aerosol canister in place. Canister support webs 93 extend transversely from said side panel to said side panel to support said aerosol canister (upper and lower parts depicted in broken line as 6), the shaping of said canister support webs being complementary to the exterior shape of said aerosol canister. In the preferred embodiment, supporting member 83 (as depicted in Figure 12) is inserted between upper and lower guide rails 194 formed on the inner surfaces of said side panels and secured in position by bonding using a suitable adhesive. The upper edges of said side panels are extended across above the upper end of said aerosol canister to form fixed contact member 195. Said fixed contact member is provided with slotted recess 112 to permit egress of said discharge nozzle of said aerosol canister. Said frame back plate is optionally extended upwards above said fixed contact

member and has formed on its forward surface gusset 113 which acts to buttress said fixed contact member. Tray 198 and rails 199 are provided on the lower edge of said frame back plate to accommodate a battery holder (not shown) slid into position on said tray and rails. Said battery holder is withdrawn from said rails to facilitate replacement of said batteries, conductors to said battery holder being of sufficient length to facilitate this. In one alternative embodiment (not shown), a battery holder is made separately and is bonded to said frame back plate adjacent one side panel, being substantially beneath (that is to say, covered by) said aerosol canister when said canister is installed in said automatic aerosol deodorant discharge unit, hi another alternative embodiment, said battery accommodation in made as described in relation to Figure 16b. Said cover (outline depicted as 26) covers all said components and is secured in position using suitable attachment means. With reference to Figures 23 and 24, canister platform 81 is made with an aperture 222 sufficiently large to permit passage through it of electric motor 100, the ability of said canister platform to properly support aerosol canister 6 being unaffected. Said motor is made with a narrow circumferential flange 200 which passes substantially around the periphery of the casing of said motor adjacent its upper end. Said flange is accommodated within a complementary recess 202 formed in the upper edge of motor housing 86 and one or more detents 206 provided in said flange engage complementary lugs 205 provided in said complementary recess. Said motor is pressed into said motor housing and said flange and detent arrangement acts to positively restrain said motor against the downward forces generated by the co-operation of threaded rod 101 with nut 99 and against rotational displacement. In the said embodiment, thrust bearing 102 is permitted to project above the upper surface of said canister platform, being accommodated within part-spherical recess 201 provided in the base of canister 6. Pillars 95 are joined at their lower ends to the outer ends 96 of the arms of spider member 97 by dowels 203 provided in said lower ends of said pillars being pressed into complementary bores

204 provided in said outer ends of said arms of said spider member to provide a secure interference fit. Such joining arrangement is satisfactory in that, during operation of said automatic aerosol deodorant discharge unit, compressive forces always exist between said joined parts. Obviously, said arrangement of said dowels and pillars is optionally reversible. Raised edge 82 of canister platform 81 is optionally extended to fully enclose the circumference of the base of aerosol canister 6, being made of sufficient height to properly locate the lower end of said aerosol canister and thereby eliminating the need for a lower transversely-located canister support web (depicted as 93 in Figures 16a, 16b and 22). In the preferred embodiment, said raised edge is made relatively lower at the outer or front part, so as to not inhibit the placement of said aerosol canister on said canister platform, and relatively higher at the sides and inner or rearward part. Suitable indented aperture 210 is provided in supporting member 83 at its inner or rearward edge to permit passage of conductors (not shown) from batteries (depicted as 207 in Figures 25 and 26 and which are optionally situated above said supporting member) to said electric motor and said control unit circuit board situated below said supporting member. In some said embodiments in which said canister platform and said aerosol canister are raised to effect a discharge of deodorant from said aerosol canister, the weight of said aerosol canister causes said actuation mechanism to return to its deactivated position. In other said embodiments, the weight of said aerosol canister assists in effecting such return. With reference again to Figures 15, 17 and 19 in which semi- rotary elements of relatively large diameter are employed to raise said canister platform and said aerosol canister, suitable springs (not shown) are optionally employed to assist in returning said semi-rotary elements to their deactivated positions. In all said embodiments employing said semi- rotary elements to raise said canister platform and said aerosol canister, suitable limit switches (not shown) are employed to sense achievement of full rotational deflections of said elements or their return to said

deactivated positions.

With reference to Figures 25 and 26, in the preferred embodiment, one or more batteries 207 are accommodated in channels formed between side panels 153 and battery location fences 211 located adjacent and parallel to said side panels. Said side panels and said battery location fences are connected by end panels 212, 215, 218 dividing said channels into discrete battery compartments each said compartment accommodating one said battery. To provide better employment of space, recess 209 to partially accommodate said batteries is formed in the thickness of frame back plate 89. Contact members 213, 216, 219 of a suitable conducting material are fixed, respectively, to end panels 212, 215, 218 and provide contact means for said batteries in said battery compartments. Battery springs 214, 217 are provided at one end of each said battery to urge said batteries into contact with said contact members. Said battery springs act themselves to provide contact between said batteries and said contact members to which they are fixed. In the preferred embodiment, said contact members are made in folded form from a suitable metal material and are pressed over said end panels, small angled teeth formed on the inner surfaces of said contact members engaging the surfaces of said end panels to render removal of said contact members difficult. Said folded form of said contact members provides conduction between adjacent poles of said batteries in series arrangement in adjacent said battery compartments, hi the preferred embodiment, shallow recesses are formed in the appropriate said contact members to positively engage and locate the positive poles of said batteries and the bases of said battery springs are captured beneath suitable tabs formed in said contact members beneath the negative poles of said batteries. Said contact members located at the ends of a group of series-connected batteries are connected via suitable conductors 220, 221 to said electric motor and said control unit circuit board, said conductors passing as required via aperture 210. Said batteries are effectively captured in place in said battery compartments by said aerosol canister when it is installed and located by canister support webs

93, raised edge 82 of canister platform 81 (as depicted in Figure 24) and wire retainer 158 (as depicted in Figure 16a).

With reference to Figures 27, 28 and 29, in an alternative embodiment, the position of aerosol canister 6 is fixed, being supported on suitable support means having a supporting surface the position of which is indicated as 223. In the preferred embodiment, said support means are as described in relation to Figures 12 and 22. In this embodiment, said aerosol canister discharge valve is unseated as required by a discharging mechanism which applies a suitable depressing force to flange 20 of discharge nozzle 21. Said discharging mechanism comprises an electric motor 35 and associated speed reduction gear train 208 which drives a cam member 231 in the manner well known in the art. Movement of said cam member acts to depress a follower member 232 connected by strap 227, 229 to discharging member 224. Said discharging member passes across the upper end of said aerosol canister more or less normal to its longitudinal axis and discharge nozzle 21 of said canister passes up through slotted aperture 226 formed in said discharging member towards its free end. Said follower member and said discharging member are fixed rigidly to said strap and stiffened, respectively, by webs 233 and 225 fixed to said members and to the appropriate parts of said strap. Said strap passes slidingly through guides 230, 228 fixed to a side panel 153 or frame back plate 89. A suitable diy or greasy lubricant is optionally provided between said strap and said guides. The upper part 227 of said strap, adjacent said discharging member, is made thicker to better support said discharging member against forces applied to it during operation. In the preferred embodiment, said guides are fixed to said side panels or to said frame back plate by dowels 234 formed on said side panels or said frame back plate passing through suitable bores provided in thick edges 235 of said guides, the outer ends of said dowels being fused, where the material permits, to retain said guides in place. A suitable roller is optionally provided on the free end of said cam member to provide rolling contact said follower member, thereby reducing friction between the two

components.

With further reference to Figure 27 and reference again to Figures 11 and 13, in an alternative embodiment (not shown) the electric motor 35, speed reduction gear train 208 and cam member 231 of Figure 27 are employed to lift canister platform 81 of Figure 11 and thereby aerosol canister 6, urging flange 20 of discharge nozzle 21 against fixed contact member 111 to depress said discharge nozzle and unseat said aerosol canister discharge valve to effect a release of deodorant in the manner previously described. With reference to Figure 30, in an alternative embodiment, control unit circuit board 13 is fixed to straight fixing element 88 (depicted in Figure 11) or frame back plate 89 by suitable pegs 236 passing through suitable holes provided in said circuit board to create a secure interference fit when said circuit board is pressed over said pegs. Raised boss 307 provided at the base of each said peg acts to support said circuit board clear of its said mounting surfaces to better permit cooling and to avoid adverse effects which might result from the accumulation of moisture on said mounting surfaces.

With reference to Figures 31 and 37, in another alternative embodiment similar to that described in relation to Figures 27, 28 and 29, the position of aerosol canister 6 is fixed, said canister being supported on suitable support means having a supporting surface, the position of which is indicated as 308. Ln the preferred embodiment, said support means are as described in relation to Figures 12 and 22. In this embodiment, said aerosol canister discharge valve is unseated as required by a discharging mechanism which applies a suitable depressing force to flange 20 of discharge nozzle 21. Said discharging mechanism comprises an electric motor, speed reduction gear train and cam member as described in relation to Figures 27, 28 and 29, movement of said cam member acting to depress a pivoting follower member 248 connected by wire or cable 245 to pivoting discharging member 238. Said discharging member passes across the upper end of said aerosol canister more or less normal to its

longitudinal axis and discharge nozzle 21 of said canister passes up through slotted aperture 244 formed in said discharging member towards its free end. Said follower member and said discharging member are stiffened, respectively, by webs 309 and 239 fixed to them. Accommodation member comprising flange 242 and hemispherical boss 246 is provided between said discharging member and flange 20 of discharge nozzle 21 to accommodate the angular displacement of said discharging member during its operation. Said hemispherical boss slidingly engages a complementary socket provided in the lower surface of dome 241 formed on said discharging member and flange 242 of said accommodation member abuts flange 20 of said discharge nozzle. Suitable clearance 310 is provided between the under surface of said discharging member and the upper surface of flange 242 and suitable clearance 243 is provided between the sides of slotted aperture 244 and discharge nozzle 21, both said clearances to accommodate the angular displacement of said discharging member during its operation. Discharging member 238 is pivotally supported on hinge 240 fixed to side panels 153 or frame back plate 89. Follower member 248 is pivotally supported on hinge 249 fixed to supporting strut 250 which is, in turn, supported from side panels 153, frame back plate 89 or a transverse panel passing between said side panels. Wire or cable 245 is pivotally fixed to attachment means provided, respectively, at the free ends 247 and 251 of said discharging member and said follower member, an eye provided at each of the ends of said wire or cable being captured by a suitable pin passing through said attachment means. Suitable clearance is provided to permit the installation of said aerosol canister in said automatic aerosol deodorant discharge unit with said accommodation member in place over said discharge nozzle, sufficient movement of said discharging member being generated by said electric motor, speed reduction gear train, cam member and follower member to take up said clearance and effect the necessary unseating of said aerosol canister discharge valve.

With reference to Figures 22 and 32, in an alternative embodiment,

tray 198 and rails 199 are provided fixed to the lower part of frame back plate 89 to accommodate a battery holder 259 slid into position on said rails. Batteries 207 are pressed into suitable channels 260 formed in said battery holder. To ensure positive capture of said batteries, the openings of said channels are made slightly smaller in width than the diameter of said batteries and suitable clearance is provided at said rails to permit a small, temporary, elastic expansion of said battery holder as said batteries are installed. Said battery holder is withdrawn from said rails to facilitate replacement of said batteries, conductors to said battery holder being of sufficient length to facilitate this.

With reference again to figures 27 and 37, suitable springs (not shown) are employed to urge said discharging mechanisms towards their deactivated positions following reversion of said electric motor 35, speed reduction gear train 208 and cam member 231 to their deactivated positions.

With reference to Figure 33, switches 172 are fixed to the outer end of supporting strip 254 with suitable fastenings 255. The inner end of said supporting strip is bonded with a suitable adhesive into slot 252 between raised ribs 253 formed on side panels 153 or frame back plate 89. hi the preferred embodiment, said supporting strip is made from a suitable dielectric material and its length is such that ready access is obtained to said switches when said cover is removed. Where said supporting strip is fixed to said frame back plate, said ribs are preferably located such that said switches abut and are thereby supported by the inner surface of said side panels. In this embodiment, separate conductors are provided from said switches to said control unit circuit board.

With reference to Figure 34, switches 172 are fixed to the outer end of supporting strip 254 with suitable fastenings 255. In the preferred embodiment, said supporting strip is made from a suitable dielectric material, its inner end is fixed to an edge of control unit circuit board 13 and its length is such that ready access is obtained to said switches when said cover is removed. Said edge of said circuit board is preferably

located such that said switches abut and are thereby supported by the inner surface of said side panels. In this embodiment, printed circuit conductors from said circuit board optionally continue along said supporting strip to communicate with said switches. With reference to Figure 35, switches 172 are bonded directly to side panels 153 or frame back plate 89, locating pins 256 provided on the inner attachment surface of said switches engaging complementary bores provided in said side panels or said frame back plate. The location of said switches is such that ready access is obtained to them when said cover is removed. In this embodiment, separate conductors are provided from said switches to said control unit circuit board.

With reference to Figure 36, in an alternative embodiment, guides

228 (as depicted in Figure 28) are bonded directly to side panels 153 or to frame back plate 89, locating dowels 257 formed on the inner attachment surfaces of thick edges 235 of said guides engaging complementary bores

258 provided said side panels or said frame back plate.

With reference again to Figures 11, 12, 22, 23, 24, 25, 26, 30 and 32, in the preferred embodiment, the component parts of said automatic aerosol deodorant discharge unit is assembled in the following sequence: 1. Application of adhesive attachment pads 153 to reverse surface of frame back plate 89 in desired positions, including on floating panels 196;

2. Interconnection with suitable conductors of contact members 213, 216, 219, electric motor 100, control switches 172, warning lights 150 and control unit circuit board 13 ;

3. Installation of contact members 213, 216, 219 on end panels 212, 215, 218;

4. Installation of electric motor 100 (together with threaded rod 101) into motor housing 86 (ensuring detents 206 in flange 200 are engaged with lugs 205);

5. Passing of pillars 95 down through lubricated pillar bushes 85 ;

6. Pressing of dowels 203 at the lower ends of pillars 95 into

bores 204 in the outer ends 96 of spider member 97, simultaneously with engagement of threaded rod 101 with nut 99 of said spider member;

7. Mounting (by clips) of control switches 172 and warning lights 150 on skirt 105 (or other position, as appropriate);

8. Installation of support member 83 (with electric motor 100 and spider member 97 in place) into guide rails 194 formed on the inner surfaces of side panels 153 and securing it by bonding using a suitable adhesive — electrical conductors being simultaneously passed as required through indented aperture

210;

9. Mounting of control unit circuit board 13 by pressing over pegs formed on frame back plate 89.

Assembly of said automatic aerosol deodorant discharge unit is thus completed without any requirement for the use of tools and is ready for the installation of aerosol canister 6, batteries 207 (together with, if appropriate, battery holder 259) and cover 26.

With reference to Figures 38, 39, 40 and 41, at start (261) of the operational sequence of a typical embodiment of said automatic aerosol deodorant discharge unit, said unit is fully assembled with said aerosol canister and batteries installed. Said unit is switched on (262) and, if provided, said re-set button is pressed. With said unit switched on, said control unit detects said batteries (263) and compares their voltage (264) with a stored minimum permissible voltage value. If the voltage of said batteries is below said minimum permissible value, a warning is initiated (265) in the form of a flashing light emitting diode (or optional audible tone warning). In the preferred embodiment, said warning is provided infrequently and continues at progressively shorter intervals if the condition persists. If the voltage value of said batteries is satisfactory, said control unit reads the position of said mode dispensing switch (266), acquires the pre-set mode and stores it in memory (267). Said control unit zeros its dispensing counter (268) and acquires a quantity-units-per-

discharge value from the setting of said mode dispensing switch (269) and stores it in memory. Said control unit establishes the default rate of sound sampling (270), takes its first sound sampling (271) and stores the sample value in memoiy (272) as a reference value. Care is taken to ensure that cistern filling is not taking place while said first sound sampling is occurring. Said control unit then enters the battery conserving sleep state (273), awaking by timer (274) to take a second sound sampling (275). Said control unit compares said second sample value with said stored sound value (276) and, if a sound level elevation of a predetermined minimum magnitude is detected, changes to an accelerated sound sampling rate (277). A series of closely-spaced, confirmatory sound samplings is then taken (278) and their averaged value compared with said stored sound value (279). If said confirmatory sound samplings confirm said magnitude of sound level elevation, said deodorant discharging mechanism is activated (293). Whenever said deodorant discharging mechanism is activated, said quantity-units-per-discharge value is added to the discharge sum value held in memory (zero at this stage) (294) and, if the new sum value exceeds a predetermined value, a warning is initiated (295) in the form of a flashing light emitting diode (or optional audible tone warning). In the preferred embodiment, said warning is provided infrequently and continues at progressively shorter intervals if the condition persists. If said confirmatory sound samplings fail to confirm said sound level elevation, normal operation is resumed. If said second sound sample value compares with said stored sound value, normal operation continues with entry into sleep state (280) and waking (281) to take a third sound sampling (282). Said control unit compares said third sound sample value with said stored sound value (283) and, if a sound level elevation of a predetermined minimum magnitude is detected, proceeds as previously (303). If said third sound sample value compares with said stored sound value, normal operation continues with entry into sleep state (284) and waking (285) to take a fourth sound sampling (286).

Said control unit compares said fourth sound sample value with said

stored sound value (287) and, if a sound level elevation of a predetermined minimum magnitude is detected, proceeds as previously (304). If said fourth sound sample value compares with said stored sound value, normal operation continues with entry into sleep state (288) and waking (289) to take a fifth sound sampling (290). Said control unit compares said fifth sound sample value with said stored sound value (291) and, if a sound level elevation of a predetermined minimum magnitude is detected, proceeds as previously (305). If said fifth sound sample value compares with said stored sound value, said control unit stores said fifth sample value in memory (292) as a new reference and normal operation continues with entry into sleep state (296) and waking (297) to take a sixth sound sampling (298). Said control unit compares said sixth sound sample value with said new stored sound reference value (299) and, if a sound level elevation of a predetermined minimum magnitude is detected, proceeds as previously (306). If said sixth sound sample value compares with said new stored sound value, normal operation continues with entry into sleep state (300) and waking (301), thereafter to continue normal operation (302), with the value of every fifth sound sampling value being stored in memory as a reference value. hi an alternative embodiment of the present invention (not shown), said sound level sensing microphone is deleted and replaced with a pair of small, closely-spaced, more or less parallel metal plates (not shown) supported within a supporting frame (not shown) made from a suitable immersible dielectric material. Said metal plates are connected to said control unit by suitable fully insulated conductors (not shown) and said supporting frame is placed in said toilet cistern just below the normal full water level. Flushing of said toilet is detected by said control unit by the change in resistance between said plates and, in response, said control unit initiates operation of said discharging mechanism to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. The time intervals to refill said cistern are also optionally acquired, stored in

memory by said control unit and used by said control unit to determine whether a short or long flush has occurred and, in response, to generate, respectively, a short or long discharge of deodorant. This embodiment is considered unattractive for retrofit purposes because of the need for installation of said plates in said cistern and the need for external conductors. The embodiment is, however, very suitable to be built into a cistern by the manufacturer.

In an alternative embodiment of the present invention (not shown), a suitable temperature sensor is fixed to the flush pipe of a toilet (in an embodiment where such is employed), said temperature sensor being connected to said control unit by suitable conductors (not shown). The change in measured temperature caused by said flow of flush water through said flush pipe is registered by said control unit as a toilet flush and said control unit initiates operation of said discharging mechanism to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. This embodiment is considered unattractive for retrofit purposes because of the need for installation of said temperature sensor on said flush pipe, the need for external conductors, the relatively slow response of said temperature sensor and the small temperature change in said flush pipe at some ambient temperatures.

In an alternative embodiment of the present invention (not shown), a suitable Doppler motion detection transmit-and-receive aerial unit (not shown) is mounted adjacent a flush pipe (in an embodiment where such is employed) made from a radio-transparent material and connected to said control unit by suitable conductors (not shown). Motion of said flush water through said flush pipe is detected and registered by said control unit as a toilet flush and said control unit initiates operation of said discharging mechanism to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. A radio-opaque screen is optionally placed between said Doppler aerial unit and toilet users to minimise the possibility of spurious

aerosol discharges as a result of movement by toilet users. This embodiment is considered unattractive for retrofit purposes because of the need for installation of said Doppler aerial unit and said screen on said flush pipe, the need for external conductors and the current draw associated with Doppler sensing.

In an alternative embodiment of the present invention (not shown), a suitable coil (not shown) is connected to said control unit by suitable conductors (not shown) and fixed to the side of a toilet cistern beneath said automatic aerosol deodorant discharge unit. Said coil is optionally incorporated into frame members 1, 2, 3 (as depicted in Figures 1 and 2). The change in capacitance caused by emptying of said cistern is detected by said control unit as a toilet flush and said control unit initiates operation of said discharging mechanism to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. In an alternative arrangement of this embodiment (not shown) a proprietary capacitance sensor is employed in place of said coil. This embodiment is considered unattractive for retrofit purposes because of the need for installation of said coil and the precise adjustment necessary to discriminate between the capacitance of a full and empty cistern. The embodiment is, however, very suitable to be built into some forms of cistern by manufacturers.

In an alternative embodiment of the present invention (not shown), a suitable passive infra-red detector (not shown) projects from the case of said automatic aerosol deodorant discharge unit. The presence of a person in the region of said toilet bowl is detected by said control unit as the result of a gross change in signal from said passive infra-red detector, causing said control unit to initiate operation of said discharging mechanism to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. The field of view of said passive infra-red detector is limited, as far as possible, to the immediate area of the toilet. In this embodiment, said discharge of deodorant is delayed by said control unit until the

departure of said person (detected again by said control unit as the result of a further change in signal from said passive infra-red detector) or for a predetermined time period measured from said initial signal. This embodiment is considered unattractive for retrofit purposes because of the possibility of spurious deodorant discharges as a result of the detection of non-users moving through or within the toilet area.

In an alternative embodiment of the present invention (not shown), a suitable Doppler microwave motion detector transmit and receive aerial unit (not shown) projects from the case of said automatic aerosol deodorant discharge unit. Movement of a person in the region of said toilet bowl is detected by said control unit as a signal from said Doppler aerial unit, causing said control unit to initiate operation of said discharging mechanism to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. The power and field of view of said Doppler motion detector is limited, as far as possible, to the immediate area of the toilet. In this embodiment, said discharge of deodorant is delayed by said control unit until the departure of said person (detected by said control unit as the result of a further change in signal from said Doppler aerial unit) or for a predetermined time period measured from said initial signal. This embodiment is considered unattractive for retrofit purposes because of the current draw involved in Doppler sensing and the possibility of spurious deodorant discharges as a result of the detection of non-users moving through or within the toilet area. In an alternative embodiment of the present invention (not shown), a small photovoltaic panel (not shown) is provided on the upper surface of the case of said automatic aerosol deodorant discharge unit. Current generated by light falling upon said photovoltaic panel is employed to charge said batteries of said automatic aerosol deodorant discharge unit. Electrical circuitry and electronic control for such photovoltaic charging of said batteries is well known in the art. hi the preferred embodiment, conductors from said photovoltaic panel are plug-connected to said

automatic aerosol deodorant discharge unit prior to installation of said cover.

With reference again to Figures 1 and 2, in another alternative embodiment (not shown), specially shaped nozzles are provided on said aerosol canister to direct said discharges of atomised deodorant in particular ways. For example, instead of simply directing said discharges upwardly, they are directed upwardly at an angle to the area immediately above the toilet bowl. An arrow or other visual aiming device is provided on said aerosol canister discharge nozzle to facilitate discharge alignment. With reference again to Figures 4, 5 and 6, in another alternative embodiment (not shown), said electric motor and gear mechanism is deleted and a suitable solenoid is employed to actuate said discharging mechanism to unseat said discharge valve of said aerosol canister.

With reference again to Figures 1 and 2, in another alternative embodiment (not shown), specially shaped nozzles are provided on said aerosol canister which engage discharging mechanism in a particular way, thereby preventing the use in said automatic aerosol deodorant discharge unit of unauthorised proprietary brands of aerosol canister. For example, flange 20 of discharge nozzle 21 (as depicted in Figure 13) is not provided on discharge nozzles commonly used with aerosol canisters and such canisters could not be employed for use in the present invention.

In an alternative embodiment of the present invention (not shown), said automatic aerosol deodorant discharge unit in one or more of the various embodiments described herein is incorporated by a manufacturer into a toilet cistern. In this embodiment, a recess is provided in one wall of said toilet cistern to accommodate said unit, said recess being closed by a suitable, removable, more or less flush, cover coloured to match the colour of said cistern.

In the preferred embodiment of the present invention, said covering of said automatic aerosol deodorant discharge unit is made in a variety of colours to match the common colours of toilet cisterns. hi an alternative embodiment of the present invention (not shown),

a small, compact detector unit (not shown) is fixed to the exterior surface of a toilet cistern to detect flushing of a toilet using any suitable of the methods previously described. Upon flushing of a toilet being detected, said detector unit transmits a coded radio signal to a separate, wall- mounted, automatic aerosol deodorant discharge unit (not shown) to initiate operation of its said discharging mechanism to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. Both said detector unit and said aerosol discharge unit are battery powered. Small, low-powered radio transmitters and receivers suitable for this application are well known in the art. Said detector unit embodies all of the detection, processing and data storage functions previously described in relation to the present invention. In a further alternative embodiment (not shown), a plurality of toilet cisterns is provided with said separate detector units, any of which may trigger aerosol discharges from one or more of said wall- mounted automatic aerosol deodorant discharge units. In an alternative arrangement of this embodiment, a self-contained said detector unit is fixed to said toilet flush pipe (where such is employed) and its said microphone detects the sound of flush water passage by conduction through the wall of said flush pipe.

In an alternative embodiment of the present invention (not shown) said aerosol canister and said discharging mechanism are deleted and replaced by a small electric motor to drive a small fan. When a said control unit detects flushing of a toilet cistern in one of the manners previously described, it energises said fan motor to generate a flow of air over a cake of volatile solid or gel deodorant material or a wick containing volatile liquid deodorant material supplied from a reservoir or the surface of a reservoir containing volatile deodorant material, said deodorant material thereby being vaporised, entrained in said air flow and discharged into the region in and around the associated toilet. This embodiment is considered less attractive than embodiments incorporating an aerosol canister as described previously as its deodorant effect is not as immediate

or controllable. Additionally, release of deodorant material may continue after said fan motor is stopped and may produce oppressive levels of deodorant material in a closed toilet cubicle.

In an alternative embodiment of the present invention (not shown) said aerosol canister and said discharging mechanism are deleted and replaced by a small electric motor driving a semi-rotary cam of the type well known in the art of electrically-powered air freshening devices which discharge a quantity of atomised deodorant material on a time-related basis by using a small pump supplied from a reservoir of said deodorant material. When a said control unit detects flushing of a toilet cistern in one of the manners previously described, it energises said motor to depress the plunger of said pump and thereby to generate a discharge of atomised deodorant into the area in and around said toilet. In a similar alternative embodiment (not shown), said pump plunger is depressed through the use of a suitable solenoid.

In an alternative embodiment of the present invention (not shown), an excitation transducer positioned between said automatic aerosol deodorant discharge unit and the exterior surface of said toilet cistern is maintained in contact with said exterior surface and acts to vibrationally excite the wall of said toilet cistern on a regular basis. Said control unit detects the change in natural frequency of vibration of said wall of said toilet cistern between the full and empty state and, when the empty state is detected, said control unit initiates operation of said discharging mechanism to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. This embodiment is considered unattractive for retrofit purposes because of the current draw associated with the operation of said excitation transducer.

In an alternative embodiment of the present invention (not shown), an automatic aerosol deodorant discharge unit is fixed to the side of a toilet cistern, positioned on the upper surface of a toilet cistern or fixed to the wall of door of a toilet cubicle. Said unit incorporates a light sensor

providing a signal to a control unit which interprets the signal change resulting from the transition from a higher light level to a lower light level as an indication of toilet use and triggers the discharging mechanism of said unit to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. Such electronic light sensing means are well known in the art. This embodiment is considered unattractive for retrofit purposes as the change in light level may not be properly indicative of toilet use.

In an alternative embodiment of the present invention (not shown), an automatic aerosol deodorant discharge unit is fixed to the door of a toilet cubicle. A motion sensor incorporated into said automatic aerosol deodorant discharge unit provides a signal to the control unit of said unit which interprets each second signal change (toilet user exiting) as an indication of toilet use and triggers the discharging mechanism of said unit to discharge a measured quantity of atomised deodorant from said aerosol canister for a predetermined period in the manner previously described. Such motion sensors are well known in the art. This embodiment is preferably employed in toilet cubicles having doors automatically closed by a spring, door closer or the like in which a door will be opened and closed twice per toilet use. This embodiment is considered unattractive for retrofit purposes as the opening and closing of a toilet cubicle door may not be properly indicative of toilet use.

In an alternative embodiment of the present invention (not shown) said cover is retained in place on said automatic aerosol deodorant discharge unit by suitable small magnets attracted to similar magnets or to small slugs of soft iron or the like.

In an alternative embodiment of the present invention (not shown) said automatic aerosol deodorant discharge unit is made in a form suitable for free-standing use and is simply placed to stand on the upper, horizontal exterior surface of a toilet cistern with said microphone maintained in continuous contact with said surface. In another form of this embodiment (not shown), said automatic aerosol deodorant discharge unit is deployed

in the same way, but adhered to said upper, horizontal exterior surface of a toilet cistern using suitable adhesive attachment pads.

In alternative embodiments of the present invention (not shown) said control unit circuit board is fixed in any convenient location to side panels 153 or frame back plate 89 (as depicted in Figure 22).

In all said embodiments of the present invention, said discharge of atomised deodorant material is optionally delayed for a suitable period after the said triggering event (toilet flush and the like) to minimise the possibility of ignition of flammable propellents employed in said aerosol canisters.

In an alternative embodiment of the present invention (not shown) said control unit regulates the volume of said deodorant discharged according to the recent frequency of toilet flushes - with smaller deodorant discharge volumes being delivered when toilets flushing is more frequent. Said arrangement acts to prevent excessive build-up of deodorant in a toilet cubicle.

In an alternative embodiment of the present invention (not shown) said on/off switch is made to have three positions, the third of which is a stand-by position in which all operational functions are preserved, but no discharges of deodorant occur. Return of said switch to the 'ON' position returns said automatic aerosol deodorant discharge unit to normal operation as it was at the point of stand-by selection.

In embodiments of the present invention in which that type of aerosol canister is employed in which unseating of its said discharge valve results only in discharge of a calibrated volume, said discharge valve is unseated once to generate a small volume of discharged deodorant (small shot), twice to generate a medium volume of discharged deodorant (medium shot) and three times to generate a large volume of discharged deodorant (large shot), hi this embodiment, the setting of said operational mode selection switch 73 (described in relation to Figure 10) determines the number of times said discharge valve is unseated (shot size) when a deodorant discharge is initiated.

In all embodiments of the present invention in which said deodorant discharge is nominated to take place from an aerosol canister, in alternative arrangements of these embodiments, said deodorant discharge takes place as a result of a flow of air propelled by an electrically-powered fan over a source of volatile deodorant or as the result of a pump supplied from a reservoir of deodorant and activated by an electric motor or solenoid.

Throughout the specification, claims and abstract hereof, the word 'toilet' should be taken to have the same general meaning as the word 'lavatory'.