Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
ELECTRIC SWITCH DEVICES
Document Type and Number:
WIPO Patent Application WO/2001/067580
Kind Code:
A2
Abstract:
An electric switch device comprises an actuator (10L, 10R) movable between first and second positions, an electrical generator (preferably a rotary generator such as an alternator), a drive mechanism which uses energy derived from movement of the actuator to drive the generator and thereby generate electrical power, and electrical circuitry coupled to the generator to produce an electrical output.

Inventors:
Burrow, Christopher (69 Hollyoake Terrace Watery Lane Cumbria Lancashire LA12 9DB, GB)
Application Number:
PCT/GB2001/000901
Publication Date:
September 13, 2001
Filing Date:
March 05, 2001
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
HAGER ENGINEERING LIMITED (Hortonwood 50 Telford Shropshire TF1 4FT, GB)
Burrow, Christopher (69 Hollyoake Terrace Watery Lane Cumbria Lancashire LA12 9DB, GB)
International Classes:
H01H23/00; H02K7/18; H01H9/02; H01H27/00; (IPC1-7): H02K7/18; H01H23/00
Domestic Patent References:
WO2000035064A12000-06-15
Foreign References:
US5734445A1998-03-31
US3654416A1972-04-04
US5844516A1998-12-01
GB2085663A1982-04-28
US3735412A1973-05-22
DE19620880A11997-11-27
GB2350245A2000-11-22
Attorney, Agent or Firm:
Mcneight, David Leslie (Lloyd Wise, McNeight & Lawrence Regent House Heaton Lane Stockport Cheshire SK4 1BS, GB)
Download PDF:
Claims:
CLAIMS
1. An electric switch device comprising an actuator movable between first and second positions, an electrical generator, a drive mechanism which uses energy derived from movement of the actuator to drive the generator and thereby generate electrical power, and electrical circuitry coupled to the generator to produce an electrical output.
2. A device as claimed in Claim 1 in which the actuator is mounted for angular movement between the first and second positions.
3. A device as claimed in Claim 1 or 2 in which the generator, drive mechanism and electrical circuitry are accommodated within a housing, the internal volume of the housing being no greater than about 25 cm3, preferably no greater than about 15 cm3 and more preferably no greater than about 10 cm3.
4. A device as claimed in any one of Claims 1 to 3 in which the drive mechanism includes a mechanical energy storage device which stores energy corresponding to the user effort applied during displacement of the actuator and, at a predetermined point in the operational cycle of the switch device, releases the energy for use in driving the electrical generator.
5. A device as claimed in Claim 4 in which the storage device comprises a spring which is designed to be stressed torsionally in response to displacement of the actuator.
6. A device as claimed in Claim 4 or 5 in which the energy stored by the energy storage means is substantially constant for each operation of the actuator, irrespective of the force applied to the actuator or speed of operation thereof.
7. A device as claimed in any one of the preceding claims including more than one actuator, preferably arranged for operation singly and/or in combination.
8. A device as claimed in Claim 7 in which a sensor or sensors is provided to determine which actuator or combination actuators is operational at any one time and, optionally, utilise this information in the production of the output signal.
9. A device as claimed in Claim 7 or 8 in which the drive mechanism, electrical generator and electrical circuitry are common to all actuators in the set.
10. A device as claimed in any one of the preceding claims including means defining predetermined locations of userapplied force to the or each actuator and control means for controlling the electrical output produced in dependence upon the location at which force is applied to the actuator.
11. A device as claimed in Claim 10 in which the location defining means comprises a number of switches located on the actuator.
12. A device as claimed in Claim 11 in which two or more such switches are provided on the or each actuator.
13. A device as claimed in Claim 12 in which the switches are operable singly and/or in combination.
14. A device as claimed in Claim 13 in which the the control means is arranged to discriminate between such single and/or combination modes of operation.
15. A device as claimed in any one of the preceding claims in which the or each actuator comprises a rocker arrangement.
16. A device as claimed in any one of Claims 1 to 15 in which the actuator is mounted in cantilevered fashion for pivotal movement between said first and second positions.
17. A device as claimed in any one of the preceding claims in which the drive transmission is coupled or engageable with the actuator at or adjacent a free end thereof whereby movement of the free end of the actuator is used to drive the electrical generator.
18. A device as claimed in Claim 17 in which the free end of the actuator is coupled or engaged with an elongate element which extends from adjacent the free end of the actuator towards (and optionally beyond) the pivotal axis of the actuator.
19. A device as claimed in Claim 17 or 18 in which the elongate element has a striplike configuration or comprises a filament or the like, the elongate element optionally being flexible in bending.
20. A device as claimed in any one of Claims 17 to 19 in which the elongate element is directly coupled to the actuator at or adjacent the free end of the latter.
21. A device as claimed in any one of Claims 17 to 19 in which the arrangement is such that the actuator at or adjacent its free end can bear on the elongate element and cause displacement of the latter in its direction of elongation in response to pivoting of the actuator so as to provide a mechanical advantage whereby displacement of the elongate element exceeds the corresponding displacement of the actuator responsible for displacing the elongate element.
22. A device as claimed in any one of the preceding claims in which the drive transmission includes a linearly displaceable gear element which is movable in a direction which is substantially orthogonal to an axis about which the actuator is movable.
23. A device as claimed in any one of Claims 1 to 22 in which the drive tranmission includes a rotary element around which one or more turns of an, or the, elongate element is looped in such a way that longitudinal displacement of the elongate element causes the rotary element to turn.
24. A device as claimed in any one of the preceding claims in which the arrangement is such that partial displacement of the actuator in response to user actuation is not effective to turn the rotor.
25. A device as claimed in any one of the preceding claims in which the arrangement is such that, on return movement of the actuator, the rotor is constrained from rotating in a direction opposite to that produced by user actuation of the actuator.
26. A device as claimed in any one of the preceding claims in which the actuator is constituted by a key blade.
27. A device as claimed in any one of the preceding claims in which the actuator is mounted on the switch housing in such a way that that part of the actuator touched by a user in order to effect switch operation is wholly external to the housing.
28. A device as claimed in Claim 27 in which the actuator is mounted for rocking movement in superimposed relation with a wall of the housing without penetrating into the interior of the housing.
29. A device as claimed in any one of the preceding claims in which the actuator comprises a rocker pivoted about an axis which passes through the interior of the switch housing.
30. A device, optionally as claimed in any one of the preceding claims, said device comprising a base structure for surface mounting, a useroperable actuator mounted on the base structure and a cover plate which conceals the base structure but exposes the actuator, the cover plate being removably attachable to the base structure in such a way that the cover plate is retained in place on the base structure independently of the means used to mount the base structure on a surface.
31. A device as claimed in any one of the preceding claims in which the drive mechanism comprises at least one torsion springtype clutching arrangement for transmitting drive between the actuator and the rotor.
32. A device as claimed in any one of the preceding claims in which the drive mechanism comprises a rack coupled to the actuator, a pinion engaged or engageable with the rack and a spur gear coupling the pinion to the rotor.
33. A device as claimed in Claim 32 in which the pinion and the spur gear are coupled through a torsion springtype clutch arrangement.
34. A device as claimed in any one of the preceding claims in which the rotor includes two relatively rotatable parts and energy storing spring means for rotating one of the parts to generate the electrical output.
35. A device as claimed in Claim 34, the spring means being a torsional spring in which energy is stored by winding the spring in one direction.
36. A device as claimed in 34 or 35 including clutch means for preventing stressing of the spring means in its unwinding direction during the return stroke of the actuator.
37. A device as claimed in Claim 36 in which the clutch means is provided in the drive mechanism at a point in advance of the rotor.
38. A device as claimed in any one of Claims 34 to 37 in which the spring means acts between the two parts and is stressed in response to relative rotation therebetween.
39. A device as claimed in any one of Claims 34 to 38 in which a first one of said rotor parts is driven rotatably during the operative stroke of the actuator while the second rotor part is held stationary and in which the second part is released for rotation at a predetermined point during the operative stroke so as to release energy for production of the electrical output through rotation of the second rotor part.
40. A device as claimed in Claim 39 in which the first rotor part is constrained from rotation in the reverse direction during return movement of the actuator.
41. An electric switch device including at least one actuator mounted for movement between a standby position and an operative position, an actuator movable between first and second positions, an electrical generator comprising a rotor and a stator, means for translating force applied to the or each actuator into generation of electrical energy by the generator and means utilising the electrical energy so generated to produce a digital output signal, the translating means including torsional spring means encircling the rotational axis of the rotor for storing mechanical energy produced by movement of the or each actuator and a gear train coupling the spring means to the actuator (s) so as to torsionally stress the spring means in response to usereffected operation of the actuator (s), means being provided for decoupling the spring means from the gear train at a predetermined point in the movement of the actuator (s) and to couple the spring means to the rotor to drive the same and thereby supply electrical energy to the signal producing means.
42. A device as claimed in any one of the preceding claims in which the stored energy is released to drive the rotor before the actuator reaches the second position, energy storage preferably taking place over the major part of actuator travel with energy release occurring over the remaining part of actuator travel.
43. A device as claimed in any one of the preceding claims in which the or each actuator is coupled, optionally through a lost motion coupling, to a switch element located by a push rod.
44. A device as claimed in any one of the preceding claims in which the drive mechanism or said translating means includes a mechanical drive comprising a first drive train for amplifying angular displacement of the or each actuator and coupling the amplified angular movement to a reciprocably mounted element so as to displace the latter in a first energy storing direction.
45. A device as claimed in Claim 44 in which the reciprocable element is mounted for linear reciprocation and optionally comprises a toothed rack meshing with a pinion.
46. A device as claimed in any one of the preceding claims in which the drive mechanism or translating means includes an energy storing spring through which the rotor of the electrical generator is linked to the actuator.
47. A device as claimed in Claim 46 in which the energy storing spring comprises a torsion spring.
48. A device as claimed in Claim 46 or 47 in which the drive mechanism or translating means includes a oneway drive transmitting means acting on the energy storing spring.
49. A device as claimed in Claim 48 in which the oneway drive transmitting means includes a torsion spring clutch.
50. A device as claimed in any one of Claims 46 to 49 including releasable latching means for preventing transmission of drive from the energy storing spring to the rotor.
51. A device as claimed in Claim 50 in which release of the latching means is controlled by operation of the actuator.
Description:
ELECTRIC SWITCH DEVICES This invention relates to electric switch devices, particularly remote control electric switches.

Remote control switches are, of course, well known and include such devices as remote controllers for television and audio equipment, and keys for automobile doors and alarm systems. Also available are portable switches for interior lighting. These devices can operate in one of a number of ways, as by infra red, ultra- sound or radio emission, detected at the lamp or other appliance to be controlled by a suitable receiver. Usually the transmitter part of the arrangement is powered by a battery.

In our prior International Patent Applications Nos. WO 96/28873 and WO 98/11575, we disclose an electric switch which does not require a battery or batteries to power the same. Instead, the switch is in the form of a remote control electric switch incorporating magnet-controlled vibrator means which is set into oscillation in response to operation of the switch actuator and creates electrical power for use in transmitting signals to an external receiver.

Although the use of magnetic force to store and release energy in the prior art is a particularly effective way of self-powering an electric switch, there are a number of features which may in some circumstances be perceived as disadvantageous. Thus, in the case of conventional switches used in for example domestic and office applications, users are accustomed to the"feel"of the actuator when operating the switch and perceive the somewhat different vibratory"feel"of the magnetic-type switch as being, at least to some degree, unnatural. Also, the resonating action of the prior art switches require a comparatively heavy base to counteract the forces produced by the vibrating spring and magnet which has consequences for the degree of compactness that can be achieved and also for the cost of production.

The present invention seeks to provide an improved electric switch device which substantially eliminates the perceived disadvantages of the prior art switches.

According to the present invention there is provided an electric switch device comprising an actuator movable between first and second positions, an electrical generator (preferably a rotary generator such as an alternator), a drive mechanism which uses energy derived from movement of the actuator to drive the generator and thereby generate electrical power, and electrical circuitry coupled to the generator to produce an electrical output.

The generator, drive mechanism and electrical circuitry may be constructed in a compact form so as to be accommodated within the internal volume of a housing of the switch device, the internal volume of the housing typically being no greater than about 25 cm3, preferably no greater than about 15 cm3 and more preferably no greater than about 10 cm3.

The actuator may be mounted for angular movement between the first and second positions; for example, the actuator may comprise a rocker arrangement.

The actuator may be mounted on the switch housing in such a way that that part of the actuator touched by a user in order to effect switch operation is wholly external to the housing, i. e. no provision being necessary for a through aperture in the housing for receiving such actuator part.

Thus, in one embodiment of the invention, the actuator is conveniently mounted for rocking movement in superimposed relation with a wall of the housing without penetrating into the interior of the housing.

Where the actuator comprises a rocker, it may pivoted about an axis which passes through the interior of the switch housing. In one embodiment of the invention, this is accomplished by mounting the rocker on a shaft which extends between opposite side walls of the switch housing, the rocker being arranged in superimposed relation with a wall extending between said side walls and being coupled to the shaft by a bracket extending in face to face relation with one of the side walls. Where a single actuator is provided, the rocker may be coupled to opposite ends of the shaft by a pair of brackets each extending in face to face relation with a respective one of the side walls. By avoiding mounting of the rocker relative to a through aperture in the switch housing, ingress of particles of foreign matter such as plaster particles into the housing may be substantially eliminated.

The drive mechanism may include a mechanical energy storage device, e. g. a spring, which stores energy corresponding to the user effort applied during displacement of the actuator and, at a predetermined point in the operational cycle of the switch device, releases the energy for use in driving the electrical generator.

The energy stored by the energy storage means may be substantially constant for each operation of the actuator, irrespective of the force applied to the actuator or speed of operation thereof.

The switch device may comprise more than one actuator, preferably so arranged that they may be operated singly and/or in combination.

Where more than one actuator is provided, a sensor or sensors may be provided to determine which actuator or combination actuators is operational at any one time and this information may be utilised in the production of the output signal. For instance, each actuator and combination of actuators may be dedicated to a particular function and the output signal, typically in the form of a digital pulse train, may be coded to represent the function corresponding to the actuator or combination of actuators operated.

Where a set of two or more actuators is provided, the drive mechanism, electrical generator and electrical circuitry may be common to all actuators in the set.

Certain embodiments ofthe invention may be provided with means defining predetermined locations of user-applied force to the actuator and control means for controlling the electrical output produced in dependence upon the location at which force is applied to the actuator.

The location defining means may comprise a number of switches located on the actuator. Such switches may comprise membrane switches, e. g. each membrane switch including a user touch pad provided on the actuator. For instance, there may be two, three or more such switches on the actuator. The switches may be operated singly and/or in combination and the control means may discriminate between such single and/or combination modes of operation.

In this manner, operation of a single actuator may serve to produce electrical power and utilisation of the power so generated is dependent upon which particular location-defining switch or combination of switches is contacted by the user's finger (s) during operation of the actuator.

The actuator may be mounted in cantilevered fashion for pivotal movement between said first and second positions and the drive transmission may be coupled or engageable with the actuator at or adjacent its free end whereby movement of the free end of the actuator is used to drive the electrical generator.

In one implementation, the free end of the actuator is coupled or engaged with an elongate element which extends from adjacent the free end of the actuator towards (and if desired beyond) the pivotal axis of the actuator.

The elongate element may have a strip-like configuration or it may comprise a filament or the like. Usually the elongate element will be flexible in bending.

The elongate element may be directly coupled to the actuator at or adjacent the free end of the latter or the arrangement may be such that the actuator at or adjacent its free end can bear on the elongate element and cause displacement of the latter in its direction of elongation in response to pivoting of the actuator. This latter arrangement may afford a mechanical advantage so that displacement of the elongate element exceeds the corresponding displacement of the actuator responsible for displacing the elongate element.

The elongate element may be coupled to a linearly displaceable gear element forming part of the drive transmission, e. g. a rack which in turn is used to drive a pinion.

Alternatively, the elongate element may be arranged to impart drive to a rotary element of the drive transmission by looping one or more turns of the elongate element around the rotary element in such a way that longitudinal displacement of the elongate element causes the rotary element to turn.

In a further embodiment of the present invention, the drive may include an energy storing spring through which the rotor of the electrical generator is linked to the actuator, the the energy storing spring conveniently being in the form of a torsion spring.

The drive mechanism may include a one-way drive transmitting means acting on the energy storing spring and the one-way drive transmitting means may include a torsion spring clutch.

Releasable latching means may be provided for preventing transmission of drive from the energy storing spring to the rotor, release of the latching means preferably being controlled by operation of the actuator.

According to another aspect of the invention there is provided a switch device in which the actuator is constituted by a key blade. The switch device may take any of the various forms disclosed herein.

In this aspect of the invention, the key blade is mounted by the switch device for movement, e. g. angular movement, so that the user can operate the switch device by displacing the key blade appropriately, such displacement being used to drive the electrical generator. Such a switch device may be suitable for use as a key fob, e. g. for gaining access to motor vehicles or buildings, the key blade being used to open door locks and the like on the vehicle/building and the electrical output of the switch device being used to enable and/or disable an alarm system associated with the vehicle/building.

According to a further aspect of the invention, the switch device is embodied in a remote control device as used for instance with household electrical equipment such as television sets and hi-fi equipment. In this case, the control device may have a set of switch elements provided on one face thereof and the actuator may be mounted at one side of the device for displacement, e. g. angular displacement, in a plane which is generally parallel with the face on which said switch elements are provided.

A switch device in accordance with the present invention may include a base structure for surface mounting, e. g. by means of fixing screws, a user-operable actuator mounted on the base structure and a cover plate which conceals the base structure but exposes the actuator, the cover plate being removably attachable to the base structure in such a way that the cover plate is retained in place on the base structure independently of the means used to mount the base structure on a surface.

In one embodiment, the base structure includes holes for reception of fixing screws and the cover plate is provided with projections which snap engage into the holes on the base structure so that once the base structure has been mounted on a surface by the screws, the cover plate may then be fitted to and retained by the base structure.

Although this aspect of the invention is disclosed herein in the context of a particular form of switch device, it is to be understood that it may also be applied to other forms of surface mounted switch devices including those which are hard-wired into an electrical circuit such as lighting circuitry.

The drive mechanism may be such that the rotor of the electrical generator is not directly coupled to the actuator so that partial displacement of the actuator (e. g. to less than half of its full extent of travel) is not effective to turn the rotor thereby eliminating generation of spurious electrical currents that may otherwise disturb proper operation of the switch device.

The switch device may include a transmitter for transmitting a coded output signal to which a receiver responds. The arrangement may comprise circuitry generating output signal pulses forming a codable pulse train and further comprise coding means selecting which pulses of the train are output as signal to the receiver.

The arrangement may be adapted as a control for an electrical appliance.

The receiver may be embodied in the appliance and/or powered from the power source for the appliance. The control may be a simple switching action or a more comprehensive function control such as a level controller, e. g. a dimmer for an electric lamp, which may comprise switch means driving a triac, or a delay on or off, or"all"off, etc.

The switch device of the invention may be embodied in a wall mount, which may be fashioned like a conventional electric wall switch, and, indeed. mounted to all intents and purposes as a conventional wall switch would be mounted, but without the need of wiring connecting it between a power supply-the building mains supply-and the appliance. This greatly facilitates electrical installation, especially when new lighting or other appliances are being fitted to an existing building, which fitting can be readily effected without any disruption to the walls or even to the decoration.

The switch device of the invention may be embodied in a portable unit, which may be adapted for carrying in the pocket or for setting down on a table top.

Although the switch device is particularly useful for control of domestic and office electrical appliances, it is not limited to these applications and may be used in a wide variety of applications requiring remote control, e. g. as a remote control for opening and closing the doors of a vehicle and/or enabling and disabling an alarm system fitted to the vehicle. It should also be borne in mind that the device of the invention is referred to as a switch in a broad sense and is not limited to simply switching on or off of a remote appliance; for instance, the switch device of the invention may produce control signals for switching between and/or enabling and disabling different functions that can be performed by a remote appliance.

The transmitter of the switch device may be a radio frequency transmitter, although, of course, it could be an ultra-sound or infra-red or other transmitter. In some instances, the transmission of signals from the device to a remote appliance may be effected by hard wiring, e. g. electrical conductors or fibre optics.

The invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a double rocker electrical switch device in accordance with the invention with both rockers shown in the standby position; Figure 2 is a perspective view of the switch device seen from the underside of the device; Figure 3 is a similar view to that of Figure 1 but showing one of the rockers depressed to the operative position; Figures 4 and 5 are views similar to Figures 1 and 2 respectively with parts removed and broken away to show the internals of the device; Figure 6 is a perspective view of one of the rockers; Figure 7 is a perspective view of the rocker shaft and segment gear; Figure 8 is a fragmentary view showing certain components on an enlarged scale; Figures 9 and 10 are views similar to Figures 4 and 5 respectively with one of the rockers shown depressed part way towards its operative position, part of Figure 9 being cut away to show the dog clutch arrangement; Figures 11 and 12 are views similar to Figures 4 and 5 showing the one rocker fully depressed to its operative position just prior to release of stored energy, part of Figure 11 being enlarged to show the link arm coupling between the radius arm and rack; Figures 13 and 14 are views similar to Figures 11 and 12 following release of stored energy; Figure 15 is a schematic diagram of electronic circuitry associated with the switch device.

Figure 16 is a perspective view of a switch device according to the invention as implemented in the form of a wall-mounted switch device; Figure 17 is perspective view showing internal components of the switch device of Figure 16; Figures 18 and 19 are similar views to that of Figure 17 but showing further internal components of the switch; Figure 20 is a sectional view of the switch device; Figure 21 is a broken away view of the base structure; Figures 22 and 23 are enlarged views showing the electrical generator and a double clutch arrangement in different operational conditions; Figure 24 is a view similar to that of Figure 16 but showing a three gang, seven channel switch device; Figure 25 is a view similar to Figure 16 of an alternative form of switch device; Figure 26 is a diagrammatic view of a modified embodiment; Figure 27 is a further diagrammatic view showing a further elaboration of the modification shown in Figure 26; Figure 28 is a perspective view of the switching device as embodied in a key fob; Figures 29a and 29b are perspective views of the switching device as embodied in a portable handheld remote control device.

Figure 30 is a perspective view of a further embodiment of drive mechanism with the rack in its retracted position; Figure 30A is a detail view of the pinion/spur assembly forming part of this embodiment; Figure 31 is a view similar to that of Figure 30 but showing additional details; Figure 32 is a similar view to that of Figure 31 (with some detail omitted) but showing the rack in its fully extended position; Figure 33 is an underside view of the drive transmission; and Figure 34 is a similar view to that of Figure 31 (with some detail omitted) but showing the rack in its an intermediate, partly returned position.

The various embodiments of switch devices to be described below are all based on the conversion of user applied physical effort in operating a switch actuator into electrical energy which is used to produce a digital pulse train for transmission to a remote device or devices (e. g. a lighting appliance) associated with the switch device.

In broad terms, the switch devices to be described below comprise at least one actuator mounted for movement between a stand-by position and an operative position, an actuator movable between first and second positions, an electrical generator, means for translating force applied to the or each actuator into generation of electrical energy by the generator and means utilising the electrical energy so generated to produce a digital output signal. The translating means may include means for storing mechanical energy produced by movement of the or each actuator, a gear train, an electrical generator driven by the gear train and means for coupling the energy storage means to the gear drive to operate the electrical generator and thereby supply electrical energy to the signal producing means.

The mechanical energy storage means may be arranged so as to store mechanical energy as the or each actuator moves from one position to the other and release the stored energy before the actuator reaches the second position. Energy storage may take place over the major part of actuator travel with energy release occurring over the remaining part of actuator travel.

The or each actuator is conveniently coupled to a switch element located within the housing by an element such as an intergral part of the the actuator or a push rod extending through an opening in the housing. The coupling may be a lost motion coupling; for example, the arrangement may be such that the displacement of the push rod by the actuator occurs only during the final part of actuator travel from one position to the other. Means is conveniently provided for biasing the actuator to one of said positions. The actuator may displace the push rod so as to operate the switch element during movement of the actuator from said one position towards the other position.

The translating means may include a mechanical drive comprising: a first drive train for amplifying angular displacement of the or each actuator and coupling the amplified angular movement to a reciprocably mounted element forming part of mechanical energy storage means so as to displace the latter in a first energy storing direction; means for decoupling the reciprocably mounted element from the first drive train in response to the actuator reaching a predetermined point in its travel between said first and second positions whereby the energy stored up to that point is released to drive the rotor of the generator. The reciprocable element may be mounted for linear reciprocation, e. g. it may comprise a toothed rack meshing with a pinion.

Referring now to Figures 1 to 15 of the drawings, the switch device illustrated is one intended for wall mounting and has two independently operable actuators each in the form of a rocker l OL and 1 OR mounted on a casing 12 which houses a mechanism for converting the physical effort used in operating one or both rockers 10 into electrical energy which is used to produce a digital pulse train for transmission to a remote device or devices (e. g. a lighting appliance) associated with the switch device.

The casing comprises upper and lower walls 14,16 and side walls 18L and 18S. The upper wall 14 in the illustrated embodiment overhangs the side walls 18 to form a flange 20.

Each rocker lOL, lOR is pivotally mounted on the casing 12 without any requirement for a through aperture in the upper wall 14 through which contaminants such as plaster dust and fragments could otherwise enter the casing and interfere with operation of the casing internal. Each rocker I OL, 1 OR is of shallow V-configuration having arms 20 and 22 so arranged that, in one position of the rocker (see Figure 1), arm 20 lies substantially flat against the upper wall 14 with arm 22 projecting upwardly and, in a second position (the"operative"position, see rocker 1 OR in Figure 3), in which arm 22 lies substantially flat against upper wall 14 with arm 20 projecting upwardly. Both rockers are biased into the Figure 1 orientation (the"stand-by"condition).

Each rocker is mounted pivotally on the casing 12 by a depending bracket 24 which extends from the underside of the rocker, through a cut-away recess 26 in flange 20 and alongside the longer sides walls 18L, the lower end of each bracket 24 being coupled through a respective dog clutch arrangement to a rocker shaft 30 which is journalled at its opposite ends in the side walls 18L. The dog clutch comprises apertured disc 29 with diametrally opposed segment-shaped recesses 32 (see especially Figures 6 and 9) which receive complementary projections 34 carried at the ends of the rocker shaft (see especially Figures 7 and 9), the projections 34 being of reduced circumferential extent compared with recesses 32 so that each rocker l OL, l OR can move between the standby and operative positions with accompanying turning of the rocker shaft 30 about its axis without affecting the other rocker. Thus, as shown in Figure 3, one rocker (in this case lOR) is shown in the operative position while the other is in the standby position.

A finger push applied to either or both rockers displaces the same from the standby position to the operative position serves to store the mechanical energy applied in a manner to be described below. Subsequent release of the rocker (s) allows return to the standby position and is accompanied by conversion of the stored mechanical energy into electrical energy by means of an electrical generator, e. g. an alternator, 40 housed within the casing 12 and use of the electrical energy to generate a pulse train for transmission to the remote device. Switches 42L, 42R, such as a surface mounted devices (SMD), are provided on printed circuit board 44 within the casing 12 and are associated one with each of the rockers lOL, lOR so as to differentiate between the four possible conditions of the rockers, i. e. neither rocker operational, rocker 10L only operational, rocker 1OR only operational and both rockers operational. The SMD switches 42L, 42R are operated through push rods 46L, 46R which extend through the upper upper wall 14 for engagement with the underside of arm 22 of the respective rocker, the arrangement being such that the push rod is only contacted by the arm 22 to operate the respective SMD switch 42L or 42R the associated rocker has almost completed its travel from the standby position to the operative position. Typically the push rods are moved only a very limited distance in the course of being actuated, e. g. about 0.2 mm.

It will be noted that the rockers are mounted with the minimum extent of penetration of the casing. In particular, in terms of the rocker mounting arrangements, the only points of penetration are those associated with the couplings with the rocker shaft 30 and those associated with push rods 46L, 46R. At these points, the components involved may fit with close tolerances and thereby minimise the possibility of ingress of foreign material. In contrast with many rocker-type switch designs, the illustrated embodiment does not mount the rockers in registry with through apertures in the casing upper wall and thereby avoids the risk of foreign matter entering the casing interior and damaging or interfering with the relatively complex and intricate casing internals employed. It will also be noted that the rockers are mounted for pivotal motion about an axis which passes through the interior of the casing even though the rockers are wholly external to the casing and do not penetrate into the casing interior.

The effort applied by the user in pushing one or both rockers to their operative positions is stored by means of energy storage means in the form of torsion spring 50 (see for example Figure 5) located at the underside of the printed circuit board 44 immediately adjacent the lower wall 16 of the casing. Whilst both rockers are effective independently or conjointly to transfer mechanical energy to the spring 50, the effect of operating rocker l OR will be described below.

Figures 9 and 10 show the condition of the mechanism when the rocker 1 OR is part way through its stroke from the standby position to the operative position. At this point, rocker 1OR has begun to turn the rocker shaft 30 but rocker 10L remains in the standby condition by virtue of the lost motion in its dog clutch coupling with the rocker shaft. The rocker shaft 30 carries a segment gear 52 which meshes with gear 54 (see Figure 5) on shaft 56 which is mounted by side walls 18L, R immediately adjacent the underside of the upper wall 14. The gear ratio (e. g. 3: 1) between gears 52 and 54 is such that the relatively small angle through which the rocker shaft 30 turns in rocker operation is amplified and results is a somewhat larger angular rotation of the shaft 56. The shaft 56 carries a radius arm 58 which is coupled at its distal end to a generally S-shaped link arm 60 having a free end which registers with a slot 62 (best seen in Figure 14) in a rack 64 which is guided for sliding movement in a direction substantially transverse to the rocker shaft 30 and substantially parallel to the lower casing wall at a location between the latter and the printed circuit board 44. Thus, rocker operation from the standby position to the operative position is accompanied by linear displacement of the rack 64 from left to right as viewed in Figure 10 for example.

The link arm 60 is biased for engagement with the slot 62 by spring 68. As well as registering with the slot 62, the link arm also co-operates with a fixed cam surface 66 (see Figure 11) which is effective to lift the link arm, against the biasing force of spring 68, out of registry with slot 62 as the rocker approaches the operative position. At this point, the drive connection between the link arm 60 and the rack 64 is disengaged.

Return spring 70 is provided for biasing the radius arm 58 (and hence the shafts 56,30 and the rocker) to the standby position.

The rack 64 has teeth 72 for mesh with a floating pinion 74 to allow drive to be transmitted at the appropriate time to a fixed gear 76 carried on a shaft 78 which also carries spur gear 80, spur gear 80 being located adjacent the upper side of the printed circuit board 44. Rotation of spur gear 80 is transmitted through gear 82 to shaft 84 carrying spur gear 86 which meshes with gear 88 coupled to the rotor 90 of the alternator 40. However, during movement of the rocker towards the operative position, the rack rotates the floating pinion 74 but the gear 76 is not meshed with pinion 74 and consequently drive is not transmitted to the alternator rotor. Such movement instead employed to store energy by way of the torsion spring 50 which is anchored at one end 92 to the circuit board 44 and coupled at its other end 94 to the rack 64 via a recess 96 which receives the spring end 94. Thus, during movement of the rack from left to right as viewed in Figure 10, the torsion spring 50 is stressed progressively and stores mechanical energy applied by the user. The arrangement is such that each rocker acuation to the operative position is accompanied by storage of the same amount of mechanical energy, i. e. the amount of energy stored each time is substantially constant regardless of the force used to operate the rockers. If desired, the torsion spring 50 may be pre-stressed so that some energy is stored in the system when the rockers are in the standby position.

Figures 11 and 12 illustrate full depression of the rocker 1 OR to the end of its stroke. At this time, the link arm 60 has been lifted out of the slot 62 and thereby disengaged from the rack 64 as a result of co-operation between the cam surface 66 and the link arm. Also, the fully depressed arm 22 of the rocker has contacted and displaced the associated push rod 46R onto the associated SMD switch 42R to provide the electronics of the system with information as to which rocker has been actuated. In this condition, the rack is freed from the rocker thus allowing the spring 50 to drive the rack 64 back, from right to left, towards its initial position as seen in Figures 13 and 14. Such return movement of the rack shifts the floating pinion 74 into mesh with gear 76 to complete the drive connection with the alternator rotor 90 causing the latter to rotate relative to the alternator stator 98 to generate an electrical power for use in digital signal generation by the on-board electronics of the switch device. The rotor 90 continues to rotate for the duration of the return movement of the rack and depletion of inertia stored in the moving components. A small angular movement of the rotor 90 after the rack has come to rest is sufficient to push the floating pinion 74 out of mesh with the fixed gear 76, preventing gear train wind-up and possible damage. On release of the rocker, the components are all returned to the initial orientation in readiness for a subsequent operation. Typically, the gearing-up ratio between rocker shaft and the alternator rotor is of the order of 9: 1 and, in response to a single operation of one of the rockers (or both), the rotor undergoes about 8 revolutions of rotation at a speed of about 1000 to 2000 revs/minute.

The arrangement is such that the force applied to produce an output signal has no effect until the rocker is at or close to its fully depressed condition. In this way, the user is obliged to apply sufficient force to ensure full depression (and hence SMD switch operation) otherwise the desired output from the switch is not obtained. Such depression is therefore primarily used to store energy over most of the rocker travel before becoming effective to initiate signal generation so the user will tend to apply sufficient force to secure the desired end result thereby ensuring reliable operation of the device.

Although this embodiment of the invention is exemplified by an arrangement having more than one rocker, it will be understood that a single rocker embodiment rocker is not excluded.

It will be appreciated that either or both of the rockers may be operated to effect energy storage and subsequent power generation. The printed circuit board 44 mounts electronic circuitry for utilising the power generated in the production of a digital pulse train. The pulse train is transmitted to the remote device or devices by an aerial loop 100 on the printed circuit board. The electronic circuitry is illustrated schematically in Figure 15 and may comprise a microcontroller 102 which is supplied with power from generating and rectifying circuitry 104, including the alternator, in response to operation of one or both rockers 1 OR, 10L. The microcontroller 102 also receives inputs from the SMD switches associated with the rockers to allow the different rocker operating modes to be discriminated and related to the remote device to be operated and/or to the particular function the remote device is to perform. Thus, purely by way of example, operation of rocker 1 OR only may be effective to switch on and off a lighting appliance at one location, operation of rocker lOL only may be effective to switch on and off a lighting appliance at a second location while simulataneous operation of rockers 1 OR and 1 OL may be effective to switch on and off a further lighting appliance at a third location.

The microcontroller 102 is programmed to generate appropriate digital outputs which are supplied to low power transmitter 106 for transmission to the remote device (s) via aerial 100, the remote device being provided with signal receiving circuitry and associated hardware for translating the received signals into performance of the desired functions. Power dissipation circuitry 108 is provided for dumping power surplus to requirements. If desired, the microcontroller may have an operator interface 110 to allow for entry of user-settable functions. A reset device 112 is also provided for ensuring a clean power-up reset of the microcontroller to avoid sporadic operation of the latter. Thus, for example, on operation of one or both of the rockers, the reset device may delay operation of the microcontroller until the voltage output derived from the electrical generator reaches a predetermined threshold value consistent with proper functioning of the microcontroller.

The switch device illustrated is of compact design and may be used in a variety of applications requiring remote control. Although the rockers are independently operable, the drive transmission, energy storage and power generation are shared by the rockers. It will be be appreciated that the design may be readily adapted to incorporate a further rocker or rockers coupled to a common rocker shaft with provision of means, e. g. SMD switches, for discriminating between the different possible permutations of rocker actuation. Thus, with a triple rocker design, in addition to single rocker actuation further information can, if desired, be input using different combinations of rocker actuation comprising simultaneous operation of pairs of rockers and also simultaneous operation of all three rockers. Also, the design may be adapted for a single rocker arrangement where desired. In this case, the rocker may be connected to opposite ends of the rocker shaft by a pair of brackets similar to those depicted by reference numeral 24 in the drawings.

Referring now to Figures 16 to 23, the switch device comprises a base 200 adapted for wall mounting by means of lugs 202 formed with screw-receiving holes 204 for reception of fixing screws. A rocker 206 is mounted on the base 200 via pivotal connections 208 located adjacent one end of the rocker so that the rocker is thereby mounted in cantilever fashion with its free end remote from the pivotal connections. The rocker 206 is biased outwardly to a first position as seen in Figures 16 and 20.

Depression of the rocker moves its free end inwardly with respect to the base 200. A cover 210 fits over the base 200 and has an opening through which the rocker projects.

The cover may be fastened to the base by the wall mounting screws which pass through holes 212. Alternatively, the cover 210 may be coupled to the base by means other than screws so that the holes 212 may be omitted. For instance, the cover may be snap engaged with the lugs 202 after base 200 has been fastened to a wall by screws passing through the holes 204. The snap engagement may be effected between projections on the back face of the cover which snap engage in the holes 204.

The rocker 206 comprises a main wall 214 and an inwardly projecting wall 216 (see Figure 20) which projects substantially perpendicularly to the main wall 214 at the free end of the rocker. The inner end of the wall 216 is engaged with a looped end formation 217 of a thin strip 218 of for example stainless steel which extends substantially perpendicularly with respect to the axis about which the rocker pivots and is anchored through a tension spring 220 to a location 222 on the base 200. The strip 218 is capable of flexing so that as the rocker 206 pivots inwardly, the strip is drawn over the base 200 in the direction A (see Figure 20). A toothed rack 224 is coupled to the strip 218 so that, as the latter moves over the base in response to pivoting of the rocker, the rack is driven in the direction A.

Referring especially to Figures 19 to 23, the rack 224 meshes with a pinion 226 which, in turn, drives a spur gear 228 mounted rotatably on the base 200. The teeth of spur gear 228 engage a pinion 230 on a shaft 232, the outer end of which projects through a slot 234 in the strip and the inner end of which bears against a disc spring 236 (see Figures 20 to 23) which biases the shaft outwardly. The shaft 232 carries the rotor 238 of an electrical generator 240, the rotor 238 being rotatably free on the shaft but axially captive therewith. The generator 240 further comprises an annular stator 250 which receives the rotor 238.

The shaft 232 also mounts a double clutch arrangement comprising a first set of one-way acting clutch elements 242,244 which are normally engaged with each other and a second set of one-way acting clutch elements 246,248 which are normally disengaged. The clutch elements 242 and 244 are respectively provided on opposed faces of members 258,260, member 258 being both rotationally and axially captive with the shaft 232 and member 260 being rotatably mounted within the base 200 and coupled to a spiral spring 254 encircling member 260. Clutch element 246 is provided on the outer face of the member 258 while clutch member 248 is provided on the inner face of the rotor.

Inward displacement of the rocker 206 brings the underside of the rocker main wall 214 into engagement with the outer end of the shaft 232, such engagement occurring towards the end of inward travel of the rocker so that the final part of the rocker 206 is effective to displace the shaft 232 inwardly to a limited extent against the biasing force of the disc spring 236. This limited degree of travel of the shaft 232 is sufficient to disengage clutch set 242,244 and engage clutch set 246,248. During that part of rocker travel preceding engagement with the shaft 232, the shaft is rotated via the rack 224, pinion 226, spur gear 228 and pinion 230 and such rotation is transferred from the clutch element 244 to the clutch element 242, causing member 260 to rotate and thereby tension the spring 254. The spring 254 acts as an energy storage device for storing the energy exerted by the user in effecting inward displacement of the rocker.

Also, during this part of rocker travel, the rotor remains stationary since it is not rotatably captive with the shaft 232.

Continued rocker travel results in inward displacement of the shaft 232 causing disengagement of clutch elements 242,244 and engagement of the clutch elements 246,248 thereby allowing the spring 254 to unwind and release its energy to drive the rotor 238 with consequent generation of electrical current for supply to electronics associated with the device for utilisation of the current so generated. Release of the rocker by the user allows the tension spring 220 to reset the various components of the drive transmission in readiness for the next operation. Also, the shaft 232 is returned outwardly by the disc spring 236 bringing clutch elements 242,244 back into engagement and disengaging clutch elements 246,248. The clutch sets 242,244 and 246, 248 may be of the toothed variety arranged so that the clutch elements transmit drive in one direction of rotational drive but ride over each other in the opposite direction.

Typically the rocker 206 is movable over a range of 10 to 20 degrees and produces at least 3, usually 5 or more, turns of the rotor 238.

In its simplest form, the switch device may be a one gang, one channel switch as shown in Figure 16, in which case the rocker 206 forms the single switch actuator and the resulting switch action is independent of the point of application of the rocker depressing force by the user. In more elaborate forms of the device however, switch operation is dependent upon the point of application of the rocker depressing force. This may be implemented by providing the rocker 206 with means for discriminating the point of application of force thereto and controlling the switch action accordingly.

Figure 24 illustrates a three gang, seven channel switch. In this embodiment, the discrimination means comprise user operable contacts 270 mounted on the rocker 206 and so arranged that finger pressure applied to a selected contact 270 serves to depress the rocker 206 and at the same time operate a switch associated with that contact.

In this way, the electronics circuitry associated with the switch device is provided with an input from the selected contact while the current generated by the generator by rocker depression is utilised by the electronics circuitry to effect the function associated with the selected contact. The contacts 270 may form part of a membrane switch assembly incorporated in the structure of the rocker and the arrangement will usually be such that the force required to operate a selected one of the membrane switches is significantly less than that necessary to displace the rocker through its full current-generating depression.

In this way, the electronics circuitry may determine in advance the function to be executed, i. e. at the beginning of the rocker depressing action.

The electronics circuitry may include a microprocessor and signal transmitting circuitry for producing encoded pulse trains dependent on the particular contact 270 used by the user during rocker depression. The circuitry may be incorporated in the rocker structure together with an aerial for transmitting the encoded signals from the device to remote receiving devices and a visual device such as a light transmitting diode 272 for providing visual confirmation that a successful switching has been executed by depression of the rocker 206. Alternatively at least part of the electronics circuitry may be provided on the base 200 and coupled to the membrane switches 270 associated with the rocker by means of a flexible printed circuit board mounted on the rocker and providing conductive tracks from the membrane switches to the electronics circuitry. The electrical circuitry may be generally similar to that described with reference to Figure 15.

The contacts 270 may be operated in single mode or in a combination mode so that a total of seven different possibilities can be generated and utilised to control different functions associated with the switch device. For instance, each contact 270 and combination of contacts 270 may be dedicated to a particular function and the output signal, typically in the form of a digital pulse train, may be coded to represent the function corresponding to the contact 270 or combination of contacts 270 operated.

Although Figure 24 illustrates an embodiment in which three contacts 270 are employed, it will be appreciated that there may be more or less depending on the number of functions to be controlled by the switch device.

The embodiments of Figures 16 to 24 are intended to, but need not necessarily, be surface mounted. Figure 25 illustrates an alternative embodiment which could for example be carried in the pocket or set down on a table top in the location of equipment etc to be controlled by the switch device.

In the embodiment of Figures 16 to 25, the drive transmission includes the strip 218, movement of which is transmitted to the rack and other gear components. In a modification as shown in Figure 26, the elongate element on which the rocker operates may be replaced by a filament or the like and whilst this filament may be used to drive the rotor of the electrical generator through gearing, a simplified form of drive transmission may if desired be used instead. Thus, as shown diagrammatically in Figure 26, the rocker 206 acts on a filament 280 which extends within the switch housing between a fixed anchorage 282 adjacent the free end 216 of the rocker 206 and the tension spring 220, the latter being connected to a fixed anchorage on the base of the switch device. Part of the filament extends between a fixed support 284 and the anchorage 282 and lies in the path of travel of the free end 216 of the rocker so that as the rocker is depressed the filament over that region is displaced downwardly as shown in phantom thereby drawing the filament in the direction B in Figure 26. A number of turns 286 of the filament are wrapped around the upper end of the generator shaft 232 so that such movement of the filament 280 is translated into rotation of the shaft 232.

Rotation of the shaft 232 may directly rotate the rotor 238 of the generator 240 or it may be initially be stored in an energy storage device and subsequently released to drive the rotor 238 as the rocker reaches or approaches the full extent of its depression. Thus, for example, the shaft 232 in the embodiment of Figure 26 may be coupled to an arrangement comprising a double clutch assembly and energy storage spring as described in relation to Figures 16 to 25. It will be observed that the manner in which the free end of the rocker co-operates with the filament gives a mechanical advantage. This mechanical advantage may be enhanced by for example providing the rocker with two or more portions 216a, 216b each co-operating with a respective section of filament located between supports 282,284a and 284b as illustrated diagrammatically in Figure 27. The filament may be made of nylon or Kevlar (Registered Trade Mark).

Figure 28 illustrates a further embodiment of the invention in which the switch device is embodied in a key fob having a key blade 290 mounted pivotally by fob housing 292, the pivot axis being depicted by reference numeral 294. The housing of the fob will include an electrical generator and associated drive mechanism and electronics which may be of the form described herein. The key blade is normally held in a fixed position for use as such but can be pivoted by the application of force exceeding a predetermined threshold so that the blade pivots sideways through an angle of say 30 degrees. For example, the blade 290 may be coupled to a mechanism which includes a spring loaded detent or a magnetic coupling for determining the threshold force needed to move the key blade from its normal position of use and thereby operate the internal electrical generator to power the electronics and transmit an electrical output to effect the desired function. The blade may be displaceable from its central position of normal use in either direction about the pivotal axis 294 and the direction of displacement may be used to control the nature of the signal transmitted by the switch device. Thus, for instance, irrespective of the direction of displacement of the blade 290 from the normal position of use, the effort applied by the user to effect such displacement may be transmitted to the rotor of the electrical generator (either directly or indirectly via an energy storage device) and the direction may be detected by the electronic circuitry so that the electrical output may be encoded to operate one function or remote device in response to displacement of the blade in one direction and to operate a different function or remote device in response to displacement of the blade in the opposite direction.

Referring now to Figures 29a and 29b, the switch device in this case is embodied in a remote control handset 300, the housing of which incorporates an electrical generator, drive transmission and electronics which may be as disclosed herein.

The handset is provided with an array 302 of selectively operable switches, e. g. touch sensitive membrane switches, by means of which various functions/channels can be selected or operated by transmission of suitably encoded signals to a remote device or devices. The power needed to produce the transmitted signals in this case is derived from operation of an actuator 304 mounted at the side of the handset so that, while holding the handset in one hand and operating the switch array with the other hand, the actuator 304 can be squeezed using the hand holding the handset substantially simultaneously with operation of one of the function/channel selection switches. The actuator 304 may be in the form of a rocker or lever and will be biased outwardly to the position seen in Figures 29a and 29b.

In all of the embodiments described herein, the switch device will typically include printed circuit board-mounted electronic circuitry for utilising the power generated by the electrical generator in the production of a digital pulse train. The pulse train may be transmitted to a remote device or devices by an aerial loop on the printed circuit board. The electronic circuitry may comprise a microcontroller and is supplied with power derived from the electrical generator of the switch device. Where the switch device has more than one mode of operation (as in the embodiment of Figure 24 for instance), the microcontroller may be programmed to discriminate between the different operating modes and relate the particular mode of operation detected to the remote device to be operated and/or to the particular function the remote device is to perform.

The microcontroller may be programmed to generate appropriate digital outputs which are supplied to a low power transmitter for transmission to the remote device (s) via an aerial, the remote device being provided with signal receiving circuitry and associated hardware for translating the received signals into performance of the desired functions. Power dissipation circuitry may be provided for dumping power surplus to requirements. Such circuitry is exemplified by way of Figure 15 and the related description.

Referring now to the embodiment of Figures 30 to 34, this illustrates a modified drive transmission that may be employed in the embodiments previously described. In this embodiment, the rotor assembly 310 of the generator comprises an annular magnet portion 312 which co-operates with the annular stator assembly 314. The rotor assembly is mounted for rotation about the axis of a fixed shaft 315 and further comprises upper and lower sections 316,318, the lower section 318 of which is rotatably fast with the annular magnetic portion 312 through a coupling sleeve 320. The upper section 316 is provided with a gear 322 meshing with spur gear 324 which is mounted for rotation about the axis of fixed shaft 326. A pinion 328 is also rotatable about the axis of the shaft 326 and meshes with a rack 330, displacement of which may be effected by the user by means of an actuator as described in previous embodiments. Energy for use in turning the magnetic portion 312 is stored by means of a torsion spring 332 which acts between the upper and lower sections 316,318.

A clutch arrangement acts between the pinion 328 and the spur gear 324 and is designed so that rotation of the pinion 328 by movement of the rack 330 in the direction M is transmitted to the spur gear 324 but rack movement in the reverse direction is not. This is accomplished in this embodiment by means of a first torsion spring 334 of helical configuration which is an interference fit on a downwardly projecting tubular extension 336 of the pinion 328, one end of the spring 334 being engaged within a slot (not shown) in a downwardly extending tubular extension 338 of the spur gear 324. As the pinion 328 rotates in response to rack movement in the direction M, the torsion spring 334 grips the tubular extension 336 and thereby transmits rotation to the spur gear 324. It will be noted that, when the pinion 328 rotates in the reverse direction, the torsion spring 334 will tend to expand and hence no longer grip the tubular extension 336 thereby decoupling the pinion 328 and the spur gear 324.

A second clutch arrangement acts between the spur gear 324 and the fixed shaft 326 and prevents bidirectional rotation of the spur gear 324. This is implemented by a second torsional spring 340 of helical configuration which is an interference fit on the shaft 326 and has one end engaged in a slot (not shown) in the tubular extension 338 of the spur gear 324. The spring 340 is wound in the opposite sense to spring 334 and is arranged so that it grips the shaft 326 if the spur gear 324 tends to rotate counterclockwise as seen in Figure 30 thereby rendering the spur gear 324 rotatably captive with the fixed shaft 326. Rotation in the clockwise direction (i. e. in response to rack movement in the direction M) is however permitted since such rotation tends to free the gripping action of the spring 340 on the shaft 326. By virtue of this clutching arrangement, it will be seen that the spur gear 324 is constrained from rotation in the counterclockwise direction and likewise prevents rotation of the gear 322 and upper section 316 in the clockwise direction. This prevents the spring 332 being stressed torsionally in a sense that could damage it or give rise to spurious energy storage and hence spurious electrical outputs.

The lower section 318 of the rotor assembly is mounted for rotation about the axis of the shaft 315 but is co-operable with means for co-ordinating such rotation with operation of the actuator (e. g. the rockers 20 or 206 in the embodiments previously described) so that such rotation is prevented until the actuator has reached a predetermined point along its path of travel. Such means is implemented in this embodiment by a latching device comprising a resiliently displaceable arm 342 which is displaced by the actuator, e. g via an extension of the rocker or a generally vertically extending push rod 344 which is engaged at its upper end by the actuator and bears at its lower end against the arm 342. The arm includes an aperture 346 having an inwardly directed projection 348 for co-operation with a keeper arrangement associated with the lower section 318. As seen in Figure 32, this keeper arrangement comprises a number of circumferentially spaced pins 350 defining gaps for reception of the projection 348.

When the switch device is in its unactuated state, the arm is positioned so that the projection 348 engages in one of the gaps between the pins 350 and thereby prevents rotation of the lower section 318. During operation of the device, at a suitable point in the cycle of operation the arm is displaced downwardly and the projection 348 is moved clear of the pins 350 to free the lower section 318 for rotation.

The operation of the mechanism shown in Figures 30 to 34 will now be described. Linear rack movement in the direction M is produced by user-actuation of the device actuator (e. g. rockers 20 or 206) which in turn rotates pinion 328. Rotation of the pinion 328 is transmitted to the upper section 316 through the clutch spring 334, spur gear 324 and gear 322. At this time, the lower section 318 is held stationary by the arm 342 with the consequence that rotation of the upper section 316 torsionally stresses the spring 332. Typically, movement of the rack may be effective to wind the spring 332 through about 5 to 6 turns. After the actuator has been pressed through a predetermined distance, the arm 342 is displaced and releases the lower section 318 thus allowing the energy stored in the spring 332 to be utilised in rotating the rotor of the generator for use in producing an output signal in the manner previously described. It will be noted that once the pushing action is completed, the upper section 316 is held stationary and remains stationary during the return stroke of the actuator and hence the rack 330.

Compared with the embodiment of Figures 16 to 23, a feature of the arrangement is that the return action of the actuator and the rack may be relatively noiseless since there is no dog-type clutching action involved.

If the user operates the actuator but does not do so to the extent needed to displace the arm 342 and release the lower section 318, then release of energy to the rotor of the generator is not possible and no signal can be generated. In these circumstances, the spring 332 will remain stressed until a proper operation of the device is effected subsequently.

Despite the relatively large number of components employed in the various embodiments of the invention, we have found that a particularly compact design is achievable in which the internal volume of the casing 12 is no greater than 20 cm3, e. g. about 15 cm3 or less. This is the case irrespective of whether a single rocker or more than one, e. g. two, rockers are used.

Many of the components of the switch device of the invention, e. g. the drive transmission components, may be manufactured as plastics mouldings thereby allowing a relatively complex design to manufactured inexpensively. Although the drive transmission is relatively intricate and potentially susceptible to damage by ingress of foreign matter, this risk may be mitigated by design of the casing and rocker arrangement in such as to eliminate entry points for material which could potentially interfere or cause damge. This is achieved while retaining the appearance of conventional light switch design using rocker actuated switching. Moreover, the"feel"of the switch device during operation is essentially the same as in conventional rocker designs and is largely free of the vibration that is encountered in switch devices such as, those disclosed in WO 98/11575 and WO 96/28873 involving oscillation of a leaf spring mounting a magnet.

The switch device of the invention may be used in conjunction with a receiver, e. g. for receiving radio frequency signals generated by the switch device. The receiver may include a discriminator for determining whether incoming signals correspond to a stored pulse sequence and suitable switching means for switching an appliance on or off when the received signal is recognised. The receiver may be powered from the same source as the appliance, namely, for example, a domestic, office or industrial mains power circuit.

Sometimes it is desired to effect a more sophisticated control than simply switching an appliance on or off ; for example a dimming control for electric lighting. In this event, the switching device may produce an output signal in response to a certain predetermined mode of operation which can be set by the user via the operator interface 110. The interface may for instance be in the form of a dial with a number of positions corresponding to different functions that are to be implemented by the appliance or appliances being controlled by the switch device. Thus, a selected function such as level of light dimming or level of increase of light intensity may be selected by the user by means of the dial so that, on operation of the switch device by means of the rocker or rockers, the switch device transmits a coded output signal which is representative of the selected function which is then acted upon at the appliance, e. g. by appropriate control of a motorised rheostat or triac to dim or increase the lighting intensity to the desired extent.

The nature of the output signals produced by the switching device may be selected according to requirements. Thus, for example, the signals may be radio frequency signals or they may be in the infra red or other wavelength region of the spectrum.

It will be noted that switch devices according to the invention can be installed in bathrooms and the like where conventional switches are not permitted, there being no danger of electric shock. In automobiles, for example, remote control switches could be installed without connection to the accumulator.

The transmitter may communicate with the receiver through wires or optical fibres and, while this this may appear self-defeating, it would enable conventional switches to be replaced with those of the invention (which do not cause any arcing) to advantage in hazardous environments.

It will be appreciated that it is not intended to limit the invention to the above examples only, many variations being possible without departing from the scope thereof as defined by the appended claims. Moreover, whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features disclosed herein and/or shown in the drawings whether or not particular emphasis has been placed on such feature or features.

It will be appreciated that the switch device of the present invention may be implemented in various forms and is not limited to the particular embodiments disclosed above. For example, the device may be embodied in a sensor device for detecting movement, e. g. by virtue of contact between a moving part (e. g. a door or a machine safety guard) and the actuator of the switch device. Or the switch device may be embodied in a personal alarm which may for example be worn by personnel with a bank or other establishment so that, in the event of the need to raise an alarm, the wearer may simple operate the actuator of the switch device to generate an alarm signal. In another implementation, the switch device may be used as a bell push.