|
Patent Abstract
An air freshener or insecticide dispenser apparatus comprises a
reservoir, an electrochemical cell for generating a gas, and varying
its rate of release. The gas generated acts on the air freshener
or insecticidal composition to dispense said composition from the
apparatus.
Patent Claims
We claim:
1. An apparatus for dispensing an air freshener or an insecticidal
composition into the atmosphere, the apparatus comprising: a reservoir
containing an air freshener or insecticidal composition; means for
generating a gas; and means for varying the rate of release of gas;
wherein, in use, gas generated by the means for generating a gas
acts on the air freshener or insecticidal composition to dispense
the composition from the apparatus.
2. An apparatus as claimed in claim 1, wherein the means for generating
a gas is an electrochemical cell.
3. An apparatus as claimed in claim 2, wherein the means for varying
the rate of release of gas comprises means for varying the resistance
of a closed external circuit formed by connecting the anode and
cathode of the electrochemical cell.
4. An apparatus as claimed in claim 3, wherein the means for varying
the resistance is a potentiometer.
5. An apparatus as claimed in claim 4, wherein the potentiometer
is employed to vary the current through the circuit between 0.08
to 0.8 mA.
6. An apparatus as claimed in claim 5, wherein the potentiometer
is employed to vary the resistance of the circuit between 2 and
20 ohms.
7. An apparatus as claimed in claim 6, wherein the resistance is
selected to ensure that the rate of gas production is maintained
at from 0.001 to 0.5 ml per 24 hour period.
8. An apparatus as claimed in any one of claims 4, 6 or 7, wherein
the means for varying the resistance is operated using an actuating
means.
9 An apparatus as claimed in claim 8, wherein the actuating means
is a lever, a button a dial.
10. An apparatus as claimed in claim 9, which further comprises
indicating means for indicating an appropriate position for the
actuating means depending on the ambient temperature.
11. An apparatus as claimed in claim 1, 4 or 7, which comprises
sensing means for sensing the ambient temperature.
12. An apparatus as claimed in claims 4 or 7, wherein the potentiometer
is a thermistor.
13. A method for dispensing an air freshener or insecticidal composition
into the atmosphere, the method comprising: providing an apparatus
as claimed in claim 1; actuating the means for generating a gas;
and allowing the gas generated to act on the air freshener or insecticidal
composition in the reservoir to dispense the air freshener or insecticidal
composition from the apparatus.
14. In an apparatus for dispensing an air freshener or an insecticidal
composition, a method to compensate for any undesired variations
in the rate at which the air freshener or insecticidal composition
is dispensed from said apparatus, which method comprises varying
the resistance in an external circuit formed by connecting the anode
to the cathode of an electrochemical cell contained within said
apparatus.
Patent Description
[0001] The present invention relates to an apparatus for dispensing
an air freshener or insecticidal composition in the vapour phase.
[0002] Various devices for dispensing air freshener and insecticidal
compositions are known. For example, the composition may be impregnated
onto a solid carrier, from which it gradually evaporates and enters
the atmosphere. Alternatively, the composition may be provided in
the form of a liquid, for example, as a thickened liquid or gel.
Such liquids are generally contained in a reservoir, formed, at
least in part, of a material that is permeable to the vapours of
the composition. As the liquid evaporates, the vapours of the composition
can permeate through the material and enter the surrounding atmosphere.
[0003] WO 96/41159 describes an electrochemical cell for generating
a gas for the transportation of fluid media. Specifically, the electrochemical
cell of WO 96/41159 is designed to produce a gas at a controlled
rate to actuate a piston or similar means to push the fluid out
of a dispenser.
[0004] A new apparatus for dispensing air freshener and insecticidal
compositions has recently been developed. The apparatus includes
an electrochemical cell for generating a gas. As more gas is produced,
the pressure in the apparatus increases. This build-up of pressure
exerts a force on the air freshener or insecticidal composition
and pushes it out of its reservoir, and onto an emanating pad, from
which it evaporates into the atmosphere.
[0005] Surprisingly, it has now been found that the gas pressure
within the apparatus is highly susceptible to fluctuations in temperature.
At low temperatures, for example, the gas generated by the electrochemical
cell contracts according to Boyle's Law. Thus, air from outside
the apparatus is drawn into the apparatus. As a result, the force
exerted on the air freshener or insecticidal composition is insufficient
to dispense the composition from its reservoir. This problem does
not arise with dispensers, such as those described in WO 96/41159,
in which the electrochemical cell is required to generate gas for
actuating a piston. In such cases, the gas is produced almost instantaneously,
to move the piston in a short period of time. Thus, the gas does
not remain in the apparatus for a sufficiently long period of time
for atmospheric temperature fluctuations to have a significant impact
on the rate at which fluid is dispensed.
[0006] According to the present invention, there is provided an
apparatus for dispensing an air freshener or an insecticidal composition
into the atmosphere, the apparatus comprising:
[0007] a reservoir containing an air freshener or insecticidal
composition;
[0008] means for generating a gas; and
[0009] means for varying the rate of release of gas;
[0010] wherein in use, gas generated by the means for generating
a gas acts on the air freshener or insecticidal composition to dispense
the composition from the apparatus.
[0011] Preferably, the means for generating a gas is an electrochemical
cell. Such a cell may be used to generate a gas by connecting the
anode and the cathode of the electrochemical cell in a closed external
circuit. The rate of release of gas may be altered by varying the
resistance of the closed external circuit, for example, by using
a potentiometer.
[0012] An advantage of the preferred embodiment described above
is that the current through the circuit can be increased when the
ambient temperature is low. This results in an increase in the rate
of gas production, which compensates for the drop in the gas pressure
in the apparatus at low temperatures. Similarly, when the ambient
temperature is high, the current through the circuit can be reduced
to decrease the rate of gas production. In this way, the gas pressure
in the apparatus is maintained at an appropriate level to ensure
that the air freshener or insecticidal composition is dispensed
at the desired rate, in spite of ambient temperature fluctuations.
[0013] Preferably, the means for varying the resistance in the
circuit is a potentiometer. The potentiometer may be employed to
vary the current through the circuit between 0.08 and 0.8 mA, preferably,
0.14 and 0.4 mA. The resistance of the circuit may be varied between
2 and 20 Ohms, preferably, 3 and 16 Ohms, and more preferably, 4
and 13 Ohms. Preferably, the resistance is selected to ensure that
the rate of gas production is maintained at a desired rate of, for
example, 0.001 to 0.5 ml per 24 hour period, preferably, 0.1 to
0.3 ml per 24 hour period.
[0014] The potentiometer may be operated manually, for example,
by using suitable actuating means. Such actuating means may take
the form of a lever(s), a button(s), a dial(s) or the like. In a
preferred embodiment, the actuating means takes the form of a lever,
which is slidably mounted within a longitudinal aperture. The aperture
may be provided with indicating means for indicating an appropriate
position for the lever according to the ambient temperature. For
example, the aperture may be provided with a temperature scale.
In operation, a user can position the lever at the appropriate temperature
indication to ensure that the resistance through the circuit is
such that the air freshener or insecticidal composition is released
at the desired rate. In an alternative embodiment, the aperture
may be provided with indications such as "high" and "low",
"hot" and "cold", or "min" and "max".
A user can position the lever at or between these extremes, depending
on the rate of release of air freshener or insecticidal composition
required. It may also be possible simply to mark the aperture with
sequential numbers, or with a colour scale, for example, of red
to blue. It should be understood that in addition to levers, the
indicating means described above can also be used in combination
with other actuating means, such as dials, buttons and the like.
[0015] The apparatus may also be provided with sensing means for
sensing the ambient temperature. For example, the apparatus may
be provided with a thermometer. Thus, a user can adjust the resistance
of the circuit according to the ambient temperature of the apparatus.
[0016] In an alternative embodiment, a thermistor is provided.
The resistance of a thermistor changes according to the ambient
temperature. Thus, an advantage of this embodiment is that the resistance
through the circuit can be varied automatically, without manual
input.
[0017] Where the resistance of the circuit is varied automatically
in response to the ambient temperature, the apparatus may be provided
with means for overriding the automatic function, allowing the resistance
to be varied manually.
[0018] The apparatus may also be provided with an on-off function
to allow the current through the circuit to be turned on and off
as desired.
[0019] Any suitable electrochemical cell for generating a gas may
be employed in the apparatus of the present invention. Examples
of suitable cells are described in WO 96/41159.
[0020] Any suitable gas can be generated to transport the air freshener
or insecticidal composition from the apparatus. Examples include
carbon dioxide, oxygen and preferably, hydrogen.
[0021] The reservoir may take the form of, for example, a tubular
housing. The reservoir may have a capacity of 5 to 20 ml, preferably,
10 to 15 ml, for example, 12 to 14 ml. In one embodiment, a reservoir
having a capacity of 14.5 ml is employed. The reservoir may be filled
with 3 to 18 ml, preferably, 10 to 12 ml of air freshener or insecticidal
composition.
[0022] The reservoir may be provided with at least one opening,
from which the air freshener or insecticidal composition is allowed
to escape. Preferably, a plurality of openings are provided. The
total cross-sectional area of the opening(s) may be 0.01 to 1.2
mm.sup.2, preferably, 0.1 to 0.5 mm.sup.2, for example, 0.1 to 0.3
mm.sup.2. Each opening may be defined by a micro-channel, which
may or may not be substantially circular in cross section. The cross-sectional
area of each micro-channel may be 0.01 to 0.4 mm.sup.2, preferably,
0.05 to 0.1 mm.sup.2, more preferably, 0.07 to 0.1 mm.sup.2. In
a preferred embodiment, 1 to 7, preferably, 2 to 5, for example,
3 openings are provided. In order to prevent the reservoir from
releasing the air freshener or insecticidal composition prematurely,
the opening or openings of the reservoir may be provided with a
seal or cover, which may be ruptured or removed when the apparatus
is ready for use.
[0023] In one embodiment, the opening or openings of the reservoir
are located at one end of the reservoir. Thus, the electrochemical
cell may be positioned at or adjacent the opposite end of the reservoir.
In use, the gas generated by the cell can act on the air freshener
or insecticidal composition and push it towards the other end of
the reservoir, and out through the opening(s). Preferably, the gas
acts directly on the composition. Thus, in such an embodiment, intervening
members such as pistons or diaphragms are not required to push the
composition out of the apparatus.
[0024] The apparatus may further comprise a protective casing to
protect at least one of the components of the apparatus from damage.
In one embodiment, the protective casing surrounds the reservoir.
Preferably, the protective casing may also surround the electrochemical
cell. The protective casing is generally provided with one or more
apertures (eg vents) through which the vapours of the air freshener
or insecticidal composition may flow into the atmosphere.
[0025] In a preferred embodiment, the apparatus is also provided
with one or more emanators for aiding the dispersion of the air
freshener or insecticidal composition into the atmosphere. In use,
the air freshener or insecticidal composition emerging from the
reservoir may drip onto the emanator, from which it evaporates into
the atmosphere. The emanator may take the form of a membrane that
is permeable to the air freshener or insecticidal composition. Such
membranes may be formed of polyethylene or paper, and are generally
thin, so as not to impede the flow of vapour into the atmosphere.
For example, the membrane may have a thickness of 20 to 100 microns,
preferably, 30 to 70 microns, and especially 40 to 60 microns. Suitable
membranes are described in U.S. Pat. No. 4,634,614 and WO 98/23304.
[0026] In order to prevent the apparatus from releasing the air
freshener or insecticidal composition before it is used, the membrane
may be covered with an impermeable sheet that can be removed when
the apparatus is ready for use. The sheet may be made of a laminate,
such as polyethylene laminated with a metal such as aluminium.
[0027] The apparatus of the present invention is particularly suitable
for dispensing an air freshener or insecticidal composition having
a relative density of 0.5 to 1.2, preferably, 0.7 to 1.0, more preferably,
0.89 to 0.98. Preferably, also the air freshener or insecticidal
composition has a flash point of 50 to 110 deg C., preferably, 60
to 95 deg C., more preferably, 65 to 88 deg C. Suitable air freshener
and insecticidal compositions are described in WO 01/00304.
[0028] According to a further aspect of the present invention,
there is provided a method for dispensing an air freshener or insecticidal
composition into the atmosphere, the method comprising:
[0029] providing an apparatus as herein described;
[0030] actuating the means for generating a gas; and
[0031] allowing the gas generated to act on the air freshener or
insecticidal composition in the reservoir to dispense the air freshener
or insecticidal composition into the atmosphere.
[0032] In yet another aspect, the present invention provides the
[0033] use of means for varying the resistance in an external circuit
formed by connecting the anode to the cathode of an electrochemical
cell,
[0034] in an apparatus for dispensing an air freshener or an insecticidal
composition,
[0035] to compensate for any undesired variations in the rate at
which the air freshener or insecticidal composition is dispensed
from the apparatus.
[0036] These and other aspects of the present invention will now
be described by way of example with reference to the accompanying
drawings, in which:
[0037] FIG. 1 is a schematic diagram of an apparatus according
to a preferred embodiment of the present invention; and
[0038] FIG. 2 is a schematic diagram of the exterior of the apparatus
of FIG. 1.
[0039] Reference is made to FIG. 1 of the drawings, which depicts
an apparatus 10 for dispensing an air freshener. The apparatus comprises
a reservoir 12 containing an air freshener, and an electrochemical
cell 14 for generating hydrogen. The electrochemical cell 14 is
connected to a potentiometer (not shown) for varying the resistance
of a closed external circuit formed by connecting the anode to the
cathode of the electrochemical cell 14. The apparatus 10 also comprises
an outer casing 16.
[0040] In use, the electrochemical cell 14 is actuated by connecting
the anode of the cell 14 to the cathode. This causes hydrogen to
be produced, which accumulates in the apparatus 10. As the gas pressure
in the apparatus 10 increases, a downward force F is exerted on
the air freshener in the reservoir 12. This downward force F pushes
the air freshener out of the reservoir 12 and onto an emanating
pad (not shown), from which it evaporates into the atmosphere.
[0041] Fluctuations in the surrounding temperature have a significant
effect on the gas pressure within the apparatus 10. For example,
when the ambient temperature falls, the gas pressure within the
apparatus 10 is reduced. Thus, although the electrochemical cell
14 is producing hydrogen, the rate of gas production is too low
to maintain the gas pressure at its optimum value. Accordingly,
the gas pressure within the apparatus 10 is insufficient for air
freshener to continue to be dispensed from the reservoir 12 at the
appropriate rate.
[0042] To overcome this problem, the potentiometer can be actuated
to reduce the resistance of the circuit. This results in an increase
in current, which in turn, raises the rate of hydrogen production.
This increase in hydrogen generation compensates for the drop in
gas pressure brought about by the fall in temperature. In this manner,
the hydrogen pressure with in the apparatus 10 can be restored to
its optimum value, allowing air freshener to be dispensed from the
reservoir 12 in the appropriate manner.
[0043] When the ambient temperature increases, the rate of hydrogen
production can be reduced by increasing the resistance of the circuit
using the potentiometer.
[0044] Reference is now made to FIG. 2, which depicts the outer
casing 16 of the apparatus 10 in greater detail. The casing 16 is
provided with a lever 18, which is slidably mounted in a longitudinal
aperture 20. The lever 18 is coupled to the potentiometer and can
be moved to alter its resistance. Thus, by sliding the lever along
the aperture as indicated by arrows P, the resistance of the circuit
can be altered to vary the rate of hydrogen generation. |