U.S. patent application number 09/518882 was filed with the patent office on 2001-11-22 for attachment method for piezoelectric elements.
Invention is credited to Clark, George A., Martens, Edward J. III, Navin, Eric R., Tomkins, David A..
Application Number | 20010042794 09/518882 |
Document ID | / |
Family ID | 22407310 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042794 |
Kind Code |
A1 |
Tomkins, David A. ; et
al. |
November 22, 2001 |
Attachment method for piezoelectric elements
Abstract
Disclosed herein is a piezoelectric liquid delivery system or
atomizer for production of droplets of liquid or liquid suspensions
by means of a battery operated atomizer utilizing an orifice plate
in communication with a ceramic piezoelectric element. By use of
solder joining to bond the orifice plate to the piezoelectric
element, and subsequent repolarization of the piezoelectric element
if necessary, superior results are achieved.
Inventors: |
Tomkins, David A.; (Racine,
WI) ; Clark, George A.; (Lewis Center, OH) ;
Navin, Eric R.; (Delaware, OH) ; Martens, Edward J.
III; (Racine, WI) |
Correspondence
Address: |
S.C. JOHNSON & SON, INC.
1525 HOWE STREET
RACINE
WI
53403-2236
US
|
Family ID: |
22407310 |
Appl. No.: |
09/518882 |
Filed: |
March 6, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60123208 |
Mar 8, 1999 |
|
|
|
Current U.S.
Class: |
239/102.2 |
Current CPC
Class: |
A61L 9/14 20130101; A01M
1/205 20130101; B05B 17/0684 20130101; B05B 17/0646 20130101 |
Class at
Publication: |
239/102.2 |
International
Class: |
B05B 001/08 |
Claims
1. A method for joining members of an atomizer which are subject to
vibration, said method comprising the of soldering a ceramic
peizoelectric member to a metallic member chosen from the group
consisting of cantilever beams, amplification plates and orifice
plates, and thereafter repolarizing the ceramic piezoelectric
member.
2. A method according to claim 1 and further including the step of
applying a paste of flux material to the surface of said ceramic
piezoelectric actuator element before soldering to cause solder to
distribute evenly over said surface.
3. An atomizer comprising an orifice plate having apertures
therein, which plate is in mechanical communication with a ceramic
piezoelectric element, a capillary feed mechanism to supply a
liquid to be dispensed to said orifice plate, and electronics to
control the dispensing of said liquid, said orifice plate being
joined to the ceramic piezoelectric element by soldering and said
ceramic piezoelectric element having been repolarized after said
soldering.
Description
PRIORITY
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/123,208, filed Mar. 8, 1999.
TECHNICAL FIELD
[0002] The present invention relates, broadly, to the field of
atomization of liquids for dispersal in the form of aerosols. More
specifically, the invention relates to means for the distribution
of a liquid active material, such as a perfume, air freshener,
insecticide formulation, or other material, in the form of fine
particles or droplets, as in a fine spray, by means of a
piezoelectric device. In particular, the invention is directed to a
piezoelectric liquid delivery system for the production of droplets
of liquid, or liquid suspensions, by means of an electomechanical
or electroacoustical actuator. More specifically, the present
invention relates to a battery operated piezoelectric dispenser
utilizing an orifice plate in communication with a piezoelectric
element. It has been found that by joining the orifice plate to the
vibrating piezoelectric element by a soldering method, rather than
the conventional adhesive or bonding techniques, performance
degradation of the piezoelectric atomization, i.e. a decline in
release rate, is avoided. This is of particular value in the
atomization of perfumes and fragrance oils, which attack the normal
adhesives, especially under high rates of flexing or vibration.
BACKGROUND ART
[0003] The distribution of liquids by formation of a fine spray, or
atomization, is well known. One method for such distribution is to
atomize a liquid by means of the acoustic vibration generated by an
ultrasonic piezoelectric vibrator. An example of such a method is
shown in Carter, U.S. Pat. No. 4,702,418, which discloses an
aerosol dispenser including a nozzle chamber for holding fluid to
be dispensed, and a diaphragm forming at least a portion of the
chamber. An aerosol dispensing nozzle is disposed therein, with a
restrictive passage for introducing fluid from the reservoir to the
nozzle. A pulse generator in combination with a low voltage power
source is used to drive a piezoelectric bender, which drives fluid
from the reservoir through the nozzle to create an aerosol
spray.
[0004] Another atomizer spraying device is shown by Humberstone et
al, in U.S. Pat. No. 5,518,179, which teaches a fluid droplet
production apparatus comprising a membrane which is vibrated by an
actuator which has a composite thin-walled structure, and is
arranged to operate in a bending mode. Fluid is supplied directly
to a surface of the membrane and sprayed therefrom in fine droplets
upon vibration of the membrane.
[0005] U.S. Pat. No. 5,297,734 of Toda teaches ultrasonic atomizing
devices comprising piezoelectric vibrators with a vibrating plate
connected thereto, by means of a conductive adhesive. In this
patent, the vibrating plate is described as having a large number
of minute holes therein for passage of the fluid.
[0006] Ivri et al, in U.S. Pat. No. 5,586,550, teach apparatus for
the delivery of therapeutic liquids, including a vibratable
non-planar member having tapered apertures, to which liquid is
delivered by squeezing a liquid reservoir to deposit it directly on
the surface, in such a manner that all of the liquid adheres to the
vibratable member by surface tension. The piezoelectric element is
bonded to a vibratory cantilever beam to provide oscillation to a
carrier plate and thin shell non-planar member so as to nebulize
the liquid in contact therewith.
[0007] U.S. Pat. No. 4,479,609, of Maeda et al, discloses a liquid
sprayer comprising an ultrasonic vibrator, a liquid supply chamber,
and a liquid absorber for transporting liquid from the chamber to
the vibrator. The electrostrictive element is connected to the
metallic horn by a conductive adhesive. Further, in U.S. Pat. No.
4,533,082, Machara et al teach an arrangement for discharging
liquid droplets, wherein a piezoelectric transducer is secured to a
vibrating member to induce a displacement of the liquid through a
nozzle opening. An axially vibrating disc is cemented to a ring
shaped piezoelectric transducer of polarized ceramic. The
disclosures of these patents, and of all other publications
referred to herein, are incorporated by reference as if fully set
forth herein.
[0008] Such atomizers and/or dispensers fail to provide a system by
which liquid to be dispersed is supplied to the vibratory
mechanism/surface without resulting in corrosion, solvent activity
by the active liquid, or bond failure at the point of joining of
the piezoelectric element and the orifice plate, particularly when
the active liquids are such as perfumes or insecticides, having
high activity quotients at high rates of vibration. Moreover, the
prior art has failed to provide an easily portable, battery
operated, continuous-action dispenser employing an orifice plate in
soldered connection with a ceramic piezoelectric element, capable
of long periods of use with little or no variation in the delivery
rate. Thus, a need exists for an improved method for joining
piezoelectric transducers to orifice plates or other elements of a
piezoelectric atomizer.
DISCLOSURE OF INVENTION
[0009] It is an object of the present invention to provide a highly
efficient, consistent, and reliable dispenser for liquid active
materials, employing an orifice plate securely joined with a
ceramic piezoelectric element. While the invention is described as
comprising a ceramic piezoelectric element, it is understood that
the invention is not limited thereto, but also extends to other
piezoelectric materials having the requisite properties for use,
and resistance to the elevated temperatures which accompany joining
elements by soldering. By liquid active materials, it is meant to
include such liquids as perfumes, air fresheners, household
cleaning materials, disinfectants, repellants, insecticides, aroma
therapy formulations, medicinals, therapeutic liquids, or other
liquids or liquid suspensions which benefit from atomization for
use. These compositions may be aqueous, or comprise various
solvents. In a preferred embodiment of the invention, the
piezoelectric liquid delivery system is easily portable, battery
operated, and conveniently refillable with the same, or a
different, liquid active
[0010] It is a further object to provide a piezoelectric pump
capable of operating efficiently for months, on low voltage
batteries, while maintaining consistency of delivery throughout the
period. Included in such object is to provide a piezoelectric
atomizer suitable for use with such electrical sources as 9 volt
batteries, conventional dry cells such as "A", "AA", "AAA", "C",
and "D" cells, button cells, watch batteries, and solar cells or
solar power. The preferred energy sources for utilization in
combination with the present invention are "AA" and "AAA"
cells.
[0011] In still another object, it is desired to provide a liquid
delivery system capable of atomizing fragrance oil or insecticide
formulation linearly over time, while maintaining the same
character/composition on the last day as was delivered on the
first, i.e. with no component change or separation with time. The
electronics of such a unit may preferably be programmable, and may
be used to set a precise delivery rate (e.g. in milligrams per
hour, or mg/hr), or may allow the consumer to adjust intensity or
effectiveness to a desired level for personal preference, efficacy,
or for room size.
[0012] Another object of this invention is to provide small
droplets of pure fragrance or insecticide formulation which are
propelled intermittently from the unit to form a small "cloud" or
"puff," which droplets quickly diffuse and move throughout a large
area on air currents present in said area. It is found that the
small size of such droplets, and the correspondingly large ratio of
surface area to mass, result in these droplets evaporating quickly
and uniformly. In preferred embodiments, the delivery system
operates with a linear delivery rate for several months on a single
1.5 volt "AA" size battery, delivering uniform volumes of
essentially equally sized droplets of the liquid for the entire
period.
[0013] These and other objects of this invention are achieved by a
piezoelectric dispenser for fragrances, insecticide formulations,
and other highly active liquids, wherein the dispenser includes a
chamber for the liquid to be dispensed, means to supply the liquid
from said chamber to an orifice plate for dispersal of the liquid,
and a ceramic piezoelectric element, wherein the piezoelectric
element is joined to the orifice plate by soldering, to achieve a
bond which is superior to conventional adhesive bonding.
[0014] The fragrance or insecticide formulation is supplied to the
back side of the orifice plate through a capillary feed system that
delivers the liquid in surface tension contact with the plate,
without damping the vibrational frequency to which the plate is
subjected by the piezoelectric element. The piezoelectric element
is driven by a small battery, capable of exciting the element and
causing it to force liquid through the orifice plate, which has a
multitude of small tapered or conical holes therein perpendicular
to the surfaces thereof, the exit of said holes being on the order
of 6 microns in diameter. Timing circuitry is used to provide an
intermittent excitation to the piezoelectric element so as to
dispense small droplets of said liquid in a time dependent fashion.
Due to the nature of the liquids being atomized, i.e. the presence
of organic components or solvents in the fragrance oils and/or
insecticide formulations, it was found that conventional bonding
methods for joining the orifice plate to the metallic cantilever
beam of a conventional piezoelectric driver were inadequate.
Conventional bonding agent exhibit significant degradation over
time when in contact with fragrance oils, with the degradation
believed to be accelerated by the flexing forces caused by the
piezoelectric vibration. A soldering process was developed to
eliminate this problem, using a lead/tin solder. In addition, it
was found that the orifice plate could be attached directly to a
piezoelectric ceramic element, eliminating the need for an extra
part such as a cantilever beam or metal amplifying plate.
[0015] These and still other objects and advantages of the present
invention will be apparent from the description which follows,
which is, however, merely of the preferred embodiments. Thus, the
claims should be looked to in order to understand the full scope of
the invention.
BRIEF DESCRIPTION OF DRAWINGS
[0016] FIG. 1 is a partial isometric view of a circuit board
suitable for use in a piezoelectric atomizer in accordance with a
preferred embodiment of the present invention.
[0017] FIG. 2 is an isometric view of a liquid container and liquid
transport means suitable to bring the liquid to the surface of the
orifice plate.
[0018] FIG. 3 is a cross sectional view showing the relationship of
the liquid container, the feed means, and the piezoelectric
element.
[0019] FIG. 4 is a magnified detail of the area of FIG. 3 enclosed
within the circle shown in FIG. 3.
[0020] FIG. 5 is a top view of the piezoelectric element and the
printed circuit board mounted on the chassis of a preferred
embodiment
[0021] FIG. 6 illustrates a much simplified cross-sectional diagram
of a piezoelectric pump assembly suitable for use with a preferred
embodiment of the present invention.
[0022] FIG. 7 illustrates a partial view, in detail, of a portion
of FIG. 6, showing the domed orifice plate in communication with a
ceramic piezoelectric element, the two elements being joined by a
solder joint in accord with the present invention.
[0023] FIG. 8 illustrates a side view of a cantilever bar type of
piezoelectric dispenser assembly.
MODES FOR CARRYING OUT THE INVENTION
[0024] While FIGS. 1 through 6 are more specifically directed to a
preferred embodiment of the invention, FIGS. 7 and 8 are more
generally directed to the full scope of the present invention,
which envisions joining of the piezoelectric element to the orifice
plate in a manner which is in contrast to the conventional practice
of those of ordinary skill in the art.
[0025] FIG. 1 illustrates the general relationship between a
printed circuit board, 1, in which the piezoelectric element 2 is
located. The circuit board, 1, is illustrated without the
electronic circuitry and battery associated therewith for clarity
and ease of understanding of the present invention. It is also to
be understood that the circuit board is, in use, attached to the
chassis of a dispenser, which chassis is in turn placed in a
decorative shell-like housing or receptacle (not shown) for use.
The chassis board 11 is shown in top view in FIG. 5, while the
housing is not illustrated. The decorative receptacle or housing
may be of any form or shape suitable for the purpose of retaining
the elements of the dispenser while providing a pleasing appearance
to the consumer, and permitting passage of the liquid, in spray
form, from the dispenser to the atmosphere. As such, the dispenser
housing may be advantageously produced by high speed molding of any
material suitable for use with, and contact with, the liquid to be
dispensed.
[0026] Piezoelectric element 2 may be mounted in the circuit board
1, held in place by grommet 4, or by any similar suitable means
which does not inhibit vibration of the piezoelectric element. The
piezoelectric element 2, in the form of a ring, is positioned in a
concentric relationship to the orifice plate 3, and is attached to
the orifice plate flange so as to be in vibratory communication
therewith. The ceramic piezoelectric element generally comprises a
piezoelectric ceramic material, such as a lead zirconate (PZT) or
lead metaniobate (PN), but may be of any material exhibiting
piezoelectric properties. The ceramic piezoelectric element is
joined to the orifice plate in the manner set forth
hereinafter.
[0027] The orifice plate comprises any conventional material
suitable for the purpose, but may preferably be comprised of an
electroplated nickel cobalt composition formed upon a photoresist
substrate which is subsequently removed in conventional manner to
leave a uniform porous structure of nickel cobalt having a
thickness of from about 10 to about 100 microns, preferably from
about 20 to about 80 microns, and most preferably about 50 microns.
Other suitable materials for the orifice plate may be utilized,
such as nickel, magnesium-zirconium alloy, various other metals,
metal alloy, composites, or plastics, as well as combinations
thereof. Other suitable materials may be used, having the
appropriate grain size and wetting properties. By forming the
nickel cobalt layer through electroplating, a porous structure
having the contour of the photoresist substrate may be produced, in
which permeability is achieved by formation of conical holes having
a diameter of about 6 microns on the exit side, and a larger
diameter on the entrance side. The orifice plate may be planar, but
is preferably dome shaped, i.e. somewhat elevated at the center,
and may vary from flat to parabolic, arc shaped, or hemispherical
in shape. The plate should have a relatively high bending
stiffness, to assure that the apertures therein shall be subject to
the same amplitude of vibration, so as to simultaneously eject
droplets of liquid which are uniform in diameter. The orifice plate
may also be plated with such materials as gold, silver, and
platinum for corrosion protection if desired.
[0028] Shown in FIG. 2 is the liquid container 5 for storage and
provision of the fragrance, air freshener, insect control liquid,
or other material to be dispensed. As illustrated, the container is
closed by a removable closure 8, preferably a clip-on or screw-on
closure. Also shown are bayonet clips 6, which are present to hold
a removable top closure, or cap, not shown, which is used in
transport and storage of the container, and may be removed easily
when it is desired to put the container into the dispenser and
permit use of the contents thereof. From bottle opening 9, exiting
through the closure 8, projects the liquid supply means 7, a loop
shaped wick or dome shaped liquid feed medium. For convenience, we
shall refer to the liquid supply means as a wick, although it may
comprise a number of varying shapes and materials, from hard
plastic capillary systems to soft porous wicks. The function of the
wick is to transport liquid from container 5 to a position in
contact with the orifice plate. Accordingly, the wick should be
unaffected by the liquid being transported, porous, and permit
compliance with the orifice plate. The porosity of the wick should
be sufficient to provide a uniform flow of liquid throughout the
range of flexibility of the wick, and in any configuration thereof.
To best transport the liquid to the surface of the orifice plate,
it has been found necessary that the wick itself physically contact
the plate, to transfer the liquid to the plate. Liquid is
preferably delivered to the orifice plate in such a manner that
essentially all delivered liquid will adhere to and transfer to the
plate surface by surface tension. Among suitable wick materials, we
have found it preferable to utilize such materials as paper, such
as filter paper, or fabrics of cotton, nylon, polypropylene, fiber
glass, etc. It is preferred that the wick comprise a highly porous
material, having porosity and softness similar to a filter paper or
tissue. A preferred wick material comprises a woven 100 percent
cotton fabric, supplied by Spring Industries as a broadcloth weave
having a 68 by 68 thread count, and a density of about 7.2 grams
per 100 square inches. The preferred loop or wick utilized is
preferably 0.125 inches wide, 2.75 inches long, and 0.01 inches
thick. The preferred loop height, above the wick holder, is
preferably from about 0.05 to about 0.15 inches, although loop
height is dependent upon design of the liquid container, wick
holder, and atomizer. The wick may preferably be shaped to conform
to the surface of the orifice plate to which it is juxtaposed, and
held in the correct position by a wick holder or positioner, 10,
located in the bottle opening 9, of the closure 8 of liquid
container 5. Liquid will flow readily from the wick to the plate as
a result of the viscosity and surface tension of the liquid. It is
to be noted that the wick is intended to be included as an integral
part of a liquid resupply unit, which will comprise the container,
the liquid, the bottle closure, the wick, and the wick holder or
positioner, as well as a top closure to seal the unit for storage
and shipment. Such a unit may thus comprise a refill bottle for the
dispenser, suitable to be placed in the dispenser at the consumers
convenience. To this end, the liquid container 5 may have
attachment means 16 on the bottle closure 8, for insertion into a
suitable receiving means in the chassis 11 to lock it in operative
position, after removal of the top closure or cap. However, it is
possible for the wick to be provided as an integral part of the
orifice plate, the chassis, or another part of the atomizer, with
means provided, such as wick tails, to bring the liquid in the
liquid container into contact with the wick.
[0029] FIG. 3 illustrates, in cross sectional view, the
relationship between the liquid container 5, the wick 7, the
piezoelectric element 2, and the orifice plate 3 of a specific
preferred embodiment of the invention. The piezoelectric element 2
is positioned, for example, in printed circuit board 1, by grommets
4, or by any suitable means which do not restrict vibration of the
piezoelectric element. In a preferred embodiment, the annular
piezoelectric element surrounds the orifice plate 3, in mechanical
connection therewith. The orifice plate is, in turn, in
juxtapostion with the wick 7, permitting flow of the liquid to be
dispensed from the container 5 to the orifice plate, where transfer
occurs through surface tension contact. Not shown is the chassis
board 11 of the dispenser, which holds the circuit board 1 and the
liquid container in the appropriate position to bring wick 7 into
juxtaposition with the orifice plate 3. Wick 7 is held in the
opening of closure 8 by the wick holder 10, which permits a degree
of freedom to the flexible and highly compliant wick 7, so as to
allow a range of adjustment thereof, while wick tail 15 assures
complete utilization of all the liquid in the container 5. This
degree of freedom permits self-adjustment of the wick relative to
the surface of the orifice is plate, to compensate for variations
in position resulting from the vagaries of manufacture and
shipment, and provides for a compliant feed means for transfer of
the liquid from the container to the face of the orifice plate. As
will be apparent to one skilled in the art, the height of the wick,
as shown in FIGS. 3 and 4, may be adjusted to vary the liquid gap
14, as shown in FIGS. 4 and 6, and to assure an appropriate degree
of contact between the wick and the plate. For a more detailed view
of the relationship between the wick and the orifice plate,
attention is directed to FIG. 4, a magnified detail of the circled
section of FIG. 3, wherein is shown the looped wick 7, in
juxtapostion with domed orifice plate 3, in which the liquid to be
transferred is in surface tension contact with the orifice plate.
While FIG. 4 shows the wick and the plate as in substantial contact
throughout the full arc of the dome of the orifice plate, it is to
be understood that this is for illustration only, and that plate 3
may in fact contact wick 7 for only a limited arc, as shown in FIG.
6, to achieve transfer of the liquid, dependent upon viscosity,
surface tension, and temperature of the liquid, as well as the
specific porosity and flexibility of the wick, and the extent of
liquid gap 14. As shown, the passage of the wick 7 through the
opening 9 in the closure element 8 is controlled by the wick
holder/positioner 10. FIG. 4 also shows the mounting grommet 4 for
the ceramic piezoelectric element 2, orifice plate 3, and the
orifice plate flange 12, as well as the clips 6 which hold the
removable cap (not shown) to the bottle closure 8.
[0030] FIG. 5 is a top view, showing the relationship of circuit
board 1, piezoelectric element 2, orifice plate 3, mounting grommet
4, and the chassis board 11, of a preferred embodiment of the
invention. As previously indicated, the piezoelectric element 2, in
concentric relationship to the orifice plate 3, is held in place in
the circuit board 1 by the grommet 4. The circuit board is mounted
on chassis board 11 in conventional manner, such as with clips 17
and positioning brackets 18.
[0031] In FIG. 6, a simplified cross sectional diagram of a
preferred embodiment of the invention illustrates the overall
relationship of various elements. The orifice plate 3 is shown as
including orifice plate flanges 12, which are in turn attached to
the piezoelectric element 2 in accordance with the present
invention. The wick 7 is illustrated in contact with the orifice
plate 3, creating liquid gap 14, in which the liquid to be
dispensed is transferred to the orifice plate. The wick is shown as
also comprising fabric tails 15, which extend into the liquid
container 5, not shown.
[0032] FIG. 7 illustrates the piezoelectric element and orifice
plate assembly of FIG. 6, wherein the ceramic piezoelectric
element, 2, surrounds the domed orifice plate 3, and is joined to
the orifice plate by soldering the orifice plate flange 12 to the
ceramic piezoelectric element at attachment points 13. In contrast
to conventional practice, we have found that this attachment means
is most appropriately a solder joint, rather than the usual
adhesive means. To achieve a successful solder joint, it is
appropriate to metallize the ceramic element to provide a base for
the solder to adhere to. It is noted that the conventional wisdom
teaches away from such a procedure, because this would require
heating the ceramic piezoelectric element to a temperature at which
depolarization thereof would occur, thus requiring repolarization
of the element. We have found that this additional step is not only
necessary, but is economically feasible, in view of the much
improved resistance to deterioration of the bond between the
ceramic element and the orifice plate, especially in the aggressive
medium of perfumes and insecticides, containing organic liquids,
which can normally diffuse into epoxy resins and destroy them. In
preparation of such a solder joint, a paste of appropriate flux
material may be silk screened in the desired pattern, which when
heated will distribute uniformly for application of the solder
bead.
[0033] While shown in the previous Figures in the form of a
concentric ceramic piezoelectric element surrounding an orifice
plate or aperture, it is also conceived that the present invention
is also suitable for use with a conventional piezoelectric element
comprising an oscillator and a cantilever beam in contact with a
diaphragm, nozzle, or orifice plate suitable for dispersion of
liquid droplets or fog, as exemplified in FIG. 8.
[0034] As previously indicated, the invention itself is not limited
to the preferred embodiments set forth heretofore, but is
applicable to any configuration of piezoelectric element and
dispensing means, such as a cantilever bar apparatus, as shown in
FIG. 8. Here, a cantilever bar 20, having attachment means 19 for
attachment to the body of an atomizer device, is in direct contact
with a piezoelectric element 2, by means of solder joint attachment
at attachment point 13. The bar is further in mechanical contact
with the orifice plate 3, shown as a domed orifice plate, while any
form may be used. The cantilever bar 20 is soldered to the orifice
plate flanges 12, at attachment points 13, to provide a continuous
and mechanically sound vibrational element for use in a
piezoelectric atomizer.
[0035] As indicated above, it has been learned that specific
combinations of improvements in the elements and methods of use of
the dispenser described result in surprisingly improved results.
Such results, however, are not limited to the preferred embodiment,
but extend to piezoelectric atomizers in general. Specifically, we
have learned that when atomizing fragrance oils and insecticide
formulations, the bond mechanism between the orifice plate and the
ceramic piezoelectric member frequently fails. In conventional
atomizers, this mechanism frequently takes the form of a cantilever
beam between the vibrating ceramic piezoelectric element and the
orifice plate or membrane. Alternatively, the orifice plate may
comprise a flange, which is mechanically joined to such transfer
means as a metal amplification plate. Joining of such members is
customarily accomplished by the use of adhesives, such as epoxy
resins and cyanoacrylate adhesive formulations. However, such
adhesive bonds are subject to degradation by aggressive media such
as fragrance oils and organic solvent containing formulations,
particularly under high frequency vibration, which promotes
diffusion into the adhesive materials. To overcome this problem, it
was found that use of a lead/tin solder eliminated such
degradation. However, conventional wisdom dictated that such heat
dependent joining means be avoided, since it resulted in
depolarization of many ceramic piezoelectric elements. Thus, after
soldering the members of the atomizer to be joined, it may be
necessary to repolarize the ceramic piezoelectric element,
dependent upon the specific properties of the piezoelectric
material. Further, it was found that by use of solder to join the
ceramic piezoelectric element directly to the metallic orifice
plate, it was possible to eliminate the need for such vibration
transfer means as the cantilever beam or an amplifying plate. For
example, it was found that when dispensing a number of fragrances,
epoxy bonded orifice plate to piezoelectric driver joints were
rapidly deteriorated. Conversely, the same fragrances had
negligible effect upon orifice plate to piezoelectric driver joints
which were soldered, even after extensive periods of use.
Industrial Appicability
[0036] The atomization systems of the present invention can be used
to automatically dispense such liquids as air fresheners, perfumes,
insecticides, or other active liquids, to any given environment,
over an extended period of time, with the advantage of uniformly
dispensing equal amounts of liquid to the atmosphere over the life
span of the battery which drives the dispenser. Further, the
dispenser may be reused at will by means of refills and replacement
batteries, so that the consumer may change the liquid being
dispersed to the atmosphere as desired, with the added advantage
that the amount of liquid being dispersed may be varied to adjust
intensity or effectiveness to a desired level for personal
preference, efficacy, or for room size.
[0037] While the present invention has been described with respect
to what are at present considered to be the preferred embodiments,
it is to be understood that the invention is not to be limited to
the disclosed embodiments. To the contrary, the invention is
intended to cover various modifications and equivalent arrangements
within the spirit and scope of the appended claims. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent
formulations and functions.
* * * * *