A DISPENSER

Field of the Invention

This invention relates to a dispenser and, in particular, to a device or element of a device for dispensing an air modifying agent into the surrounding atmosphere.

Background to the Invention

Numerous devices are available for dispensing air modifying agents, for example fragrances, into environments in which the devices are located.

Existing devices, some of which are purely passive, some of which are electrically powered, and some of which are aerosol-based, satisfy operating requirements to different extents. An air modifying device should: i) Generate droplets or particles of air modifying agent in size of the order of 4 to 8 microns, and disperse the particles into the atmosphere as quickly as possible ensuring that, once dispersed, the particles can be further dispersed by air currents applying in the atmosphere; ii) disperse particles in such as way as to discourage the particles re-combining and forming larger drops of active agent that drip

onto or about the exterior of the device; iii) operate effectively using a range of active agents; and iv) operate in an efficient and cost effective manner.

A fragrance dispenser in the form of an atomiser is briefly described in British Patent Application 2551395. Within the patent application a fragrancing liquid is described having a fragrance composition of 2-25% by weight and a carrier solvent comprising at least 50% by weight of branched chain alkanes. The latter are considered an aspiration hazard and thus require warnings on packaging. Other than mentioning the use of a piezoelectric element in combination with an orifice plate to atomise the liquid, and the use of polypropylene wick, there is little description of the physical apparatus used.

One application for dispensers of this type is in commercial bathrooms and washrooms. In such applications, the units need to be serviced by visiting service persons and it is thus important that the dispensers behave reliably and consistently between service visits to avoid needless expense associated with visits. Further, the unit should also be configured so that service can be effected in a quick and efficient manner.

It is an object of this invention to provide a form of dispenser for an air modifying agent which goes at least some way in addressing one or more of the aforementioned requirements; or which will at least provide a novel and useful choice.

Summary of the Invention

Accordingly, the invention provides a dispenser for a liquid air modifying agent, said dispenser including:

a container for said agent;

a dispensing point;

a nebulizing facility at least in part located at said dispensing point, said nebulizing facility being configured an operable to nebulize air modifying agent delivered to said dispensing point;

a wick to deliver agent from said container to said nebulizing facility; and control means operable to control the operation of said nebulizing facility, wherein

the control means is configured to initiate and control operating times of said nebulizing facility; to initiate a stop function at the end of an operating time, control a time interval before a next operating time, and initiate a next operating time; and to monitor and control an operating frequency of said nebulizing facility.

Preferably said dispensing point is integrated into said nebulizing facility.

Preferably said wick has a distal end located external to said container when said dispenser is in the operating state. Preferably said wick is formed from a cellulose material.

Preferably said container is formed with an outlet neck, said wick being retained in a wick holder engaged with said outlet neck.

Preferably said wick holder is configured to provide a mount for said nebulizing facility.

Preferably said nebulizing facility includes a piezoelectric component and a perforated foil.

Preferably said nebulizing facility further includes a housing configured to house said piezoelectric component and said foil and to locate said foil in operating association with said wick.

Preferably said perforated foil has a plan area that is greater than the cross-sectional area of said wick, said dispenser further including a transfer pad separate from but located between and in contact with both said foil and said wick, said transfer pad being configured and operable to transfer agent from said wick substantially over the whole of said plan area.

Preferably said nebulizing facility includes biasing means operable to bias said foil into contact with said delivery facility.

Preferably said container and said wick are provided as a first unit and said nebulizing facility is provided as a second unit detachably engageable with said first unit.

Preferably said nebulizing facility is configured to nebulize a liquid air modifying agent having a viscosity of less than 2.5cP and an active ingredient of greater than 25% by weight.

Preferably said nebulizer and said control system are configured to nebulize a fragrancing liquids having a fragrance content of substantially 40% by weight Preferably said nebulizing facility is configured and driven to operate at a frequency of 108 ± 5 Khz.

Preferably said control means is further operable to control a ramp up rate of power applied to said nebulizing facility at a beginning of an operating time.

Many variations in the way the present invention can be performed will present themselves to those skilled in the art. The description which follows describes one example only of combinations of elements or components for performing the invention. Within the limits of the appended claims one, more or all of the described elements may be substituted to provide an embodiment of the invention and the invention is not to be confined to the combination, whether in whole or in part, described.

Brief Description of the Drawings

One form of dispenser embodying the various aspects of the invention will now be described with reference to the accompanying drawing in which:

Figure 1: shows an exploded isometric view of a dispenser hosuing according to the invention; and

Figure 2: shows an enlarged isometric view of parts of the dispenser which are used in conjunction with the housing shown in Figure 1 to deliver an air modifying agent; and

Figure 3: shows an enlarged cross-section through a wick holder and nebulizing facility incorporated in the apparatus shown in Figures 1 & 2.

Detailed Description of Working Embodiment

Referring to the drawings, the invention provides a dispenser which includes a housing 5 in which is located a container or reservoir 6 for holding a liquid air modifying agent 7, the agent 7 being nebulized and dispensed from the housing in a manner that will be described in greater detail below. In the form shown the housing comprises a base 10 and a cover turn, being mounted in housing comprising a housing base 9, a cover 10 pivotally attached to the base 10, and an inner support 11 confined within the volume defined by the combination of base 9 and cover 10. The inner support 11 includes a first cavity 12 configured to retain batteries 13 used to power the dispenser, and a second cavity 14 configured to retain container 6. Other operating parts including a control means, preferably in the form of a micro-processor (not shown) are housed at any suitable location within the housing 5.

Whilst many different forms of air-modifying agent could be dispensed using the apparatus herein described, reference will be made hereafter to the dispensing of fragrances although the invention is not to be limited to such.

Mounted within the container 6 is a delivery facility in the form of a wick 15, which draws the fragrance 6 from the container 6 and delivers the same to a nebulizing facility 16 sited at or closely adjacent to an outlet 17 from the housing. In use the nebulizing facility 16 nebulizes or atomizes the fragrancing liquid, the resulting droplets or particles then being emitted in a plume from outlet 17 and so that fragrance released from the wick 15 passes to the outside of the apparatus and is not trapped within. In this particular example, but by no means essential, the wick and nebulizing facility are arranged so that the plume exits the apparatus along a dispensing axis 18 which is at an angle of substantially 45° up from the horizontal.

As will be described in greater detail below, control means (not shown) mounted within the housing is provided to control the operating time of the nebulizing facility and also control the time between operating times. The control means is preferably part of an electronic circuit that drives the nebulizing facility and monitors the operating frequency of the nebulizing facility to improve efficiency and reliability.

The control means may be powered from one or more batteries 13 and preferably also includes functionality to control the ramp-up of the batteries at the beginning of an operating cycle to ensure a consistent minimum operating cycle time of the nebulizing facility is achieved.

The wick 15 preferably comprises a rod of porous material, preferably porous cellulose material which may have a density of 0.296g/cm ³ although other materials and densities may present themselves. A proximal end 20 of the wick abuts against the interior wall of container 6 while a distal part 21 is supported in wick holder 22 so that, when assembled in the operating state, the distal end 21 protrudes slightly from the wick holder 22. In the form shown the container 6 is formed with a threaded outlet neck 24 such that, prior to use, a closing cap (not shown) may be screwed to the neck 24. The inner surface of the cap may be configured to set the protrusion of the wick 15 from the wick holder 22, the wick holder being a firm sliding fit within the neck 24. Thus the container 6, wick 15 and wick holder 22 are provided as a single replaceable unit.

The nebulizing facility 16 preferably comprises an annular piezoelectric ring 25, a perforated foil disc 26, a spring 27 and a support 28. The discs 25 and 26 are glued or bonded together and, together with the spring 27, are assembled into the support 28 to provide a separate unit that, in use, engages with wick holder 22. In use the facility 16 is positioned so that the assembly of discs 25 and 26 is lightly biased against a flexible absorbent pad 29 the pad 29, in turn, being biased against the distal end 21 of wick 15 by spring 27. This may be achieved by directly engaging the support 28 with the wick holder 22 or, in a further embodiment, attaching the support 28 to the inner surface of cover 10 such that, when the cover is moved into a closed position with base 9, the facility 16 engages against the pad 29. The bias applied by spring 27 is set to ensure efficient transfer of fragrancing liquid from the wick 15 to the pad 29 and, in turn, from the pad 29 across substantially the entire surface of the foil disc 26 to ensure a consistent level of delivery to the foil disc 26 during each operating cycle whilst protecting the distal end 21 of the wick from damage. The disc 29 may, for example, be formed from 2mm polypropylene sheet of density 0.170g/cm3 ± 10%. It will be appreciated that, if the bias applied by spring 27 is too low, the transfer of fragrancing liquid to the foil will be poor but if the bias is too great, the vibration of the piezoelectric disc 25 will be damped and operational efficiency will be compromised.

The driving and control of the piezoelectric disc is preferably effected by a drive and control circuit, conveniently incorporated in a microprocessor mounted on a printed circuit board (not shown) mounted within the housing base 9 and powered from batteries 13. Given the nature and range of the fragrancing liquids to be dispensed the apparatus is preferably configured to drive the piezoelectric element at a frequency of 108 ± 5Khz. A common problem experienced in prior art applications is cracking of the piezoelectric disc which, in any event, are subject to production tolerances. The present invention thus proposes a drive and control circuit for driving piezoelectric element 25 that scans the drive frequency to ensure the element 25 is driven in resonance at all time. To this end, at start-up the control means monitors the feedback from the element 25 and, if necessary, adjusts the drive frequency to ensure the element is operating in resonance. We have also observed that batteries sourced from different manufacturers differ in their responses to a power demand at the beginning of an operating cycle. The microprocessor is thus further configured to control ramp up to ensure consistent power is applied during an operating cycle to ensure that a consistent level of fragrance is dispensed in each operating cycle.

The foil disc 26 is preferably a flexible metal foil configured with perforations of around 4400 per square cm although this may vary depending on the liquid formulation and the required particle size. For this particular application the target particle size is about 4 microns.

The apparatus described above has been configured to dispense fragrancing liquids in an efficient and cost-effective manner. While we have found that some pure fragrances can be dispensed, the described apparatus can dispense a wider range if the fragrancing liquids combine a fragrance with one or more solvents.

A first factor influencing performance is the nebulizing facility. Testing with the facility described indicates that the viscosity of the fragrancing liquid should be less than 2.5cP. Since the majority of neat concentrate fragrances have a significantly higher viscosity then solvents must be used to reduce the viscosity.

Of the available solvents, petroleum distillates such as aliphatic hydrocarbons provide very good performance for nebulizing applications but can be aspiration hazards in amounts greater than 10% by weight. We thus prefer fragrancing liquids having less than 10% by weight of petroleum distillate. In making this calculation it must be recognised that some fragrances, in themselves, include aromatic hydrocarbons, and thus in event such a fragrance is selected, a reduced amount of distillate is added.

To the combination of fragrance and petroleum distillate, is preferably added a combination of glycol ethers, the respective amounts of which are tailored to the base fragrance to provide optimum performance. The objective is to deliver 0.015 - 0.020 grams of active for each 4 sec operating cycle of the nebulizing facility, with 10, 20 or 30 minutes elapsing between operations depending on the degree of fragrancing required. The controller can also be configured to vary‘on’ times if required. A glycol ether sold under the trade mark Dowanol PnP combines well with fragrances and is highly volatile. The resulting volatility can be controlled by adding in a glycol ether acetate sold under the trade mark Dowanol DPM Acetate which is also a good coupling and bulking solvent. Dowanol DPM may also be used in place of a proportion of the Dowanol DPM Acetate. Indicative (but not essential) ranges for compositions of the fragancing liquid are:

Fragrance: 20% - 70% by weight, preferably 40% by weight

Aliphatic Hydrocarbons: less than 10% by weight

Dowanol PnP: 10% - 20% by weight

Dowanol DPM Acetate: 40% - 70% by weight