Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A DEVICE FOR DISPERSING LIQUID ACTIVE MATERIALS IN PARTICULATE
FORM COMPRISING A SINTERED LIQUID CONDUCTOR
BACKGROUND OF THE INVENTION
The use of devices to generate and distribute particles into the surrounding
air is known.
Conventional devices for generating particles typically include membrane which
has orifices to
atomize a liquid. This membrane is vibrated such that particles of liquid are
formed when a
liquid is present on the membrane. The liquid is typically provided to the
membrane from a
wick. One of the problems encountered with conventional devices is that the
direct contact
between the membrane and the wick creates inefficiencies within the device
such as wear and
tear on the device; energy loss, and problems related to generating or
projecting particles.
Attempts have been made to minimize the inefficiencies by introducing liquid
conductors
composed of different materials including: stiff-wick compositions, sponge-
wick compositions,
or cloth-wick compositions. Stiff-wick conductors typically provide sufficient
liquid transport
via capillary action and sufficient structural rigidity but are subject to
dampening problems due
to the stiff non-complaint nature of the stiff-wick composition. Sponge-wick
conductors are
typically less susceptible to dampening problems due to the compliant and soft
compositions
used, but typically provide insufficient liquid transport via capillary action
and structural rigidity.
Cloth-wick conductors have also been attempted but, like sponge-wick
conductors, cloth-wick
conductors tend to provide insufficient liquid transfer and structural
rigidity. Other attempts to
address these inefficiencies have been attempted in: U.S. Pat. Nos. 4,301,093;
5,297,734,
6,293,474, and 7,017,829; European Pat. Publ. No. 0 897 755; and WO Publ. No.
2005/097349
to Burstall et al.
Despite the attempts to address the dampening effect problem encountered with
conventional devices, there remains a need for a particle generating device
which is less
susceptible to dampening effects, yet provides sufficient liquid transport to
allow for generation
and projection of particles.
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SUMMARY OF THE INVENTION
One embodiment of the present invention provides a device for generating
particles
comprising: a perforated plate comprising at least one orifice; optionally a
base plate positioned
below said perforated plate forming a space for receiving a volume of liquid;
an
electromechanical transducer operably connected to at least one of said
perforated plate and said
optional base plate; a liquid source comprising: a liquid reservoir; and a
liquid conductor in
fluid communication with said perforated plate and in fluid communication with
said liquid
reservoir, said liquid conductor comprising at least one open cell composition
and at least one
stiff-wick composition, wherein said compositions are affixed to one another
by sintering.
Another embodiment of the present invention provides a refill container
comprising: a
liquid source comprising: a liquid reservoir; and a liquid conductor in fluid
communication with
said perforated plate and in fluid communication with said liquid reservoir,
said liquid conductor
comprising at least one open cell composition and at least one stiff-wick
composition, wherein
said compositions are affixed to one another by sintering.
Yet another embodiment of the present invention provides a method for
generating
particles comprising the steps of: providing a device according to the present
invention wherein
said device contains a liquid; conducting said liquid from said liquid
reservoir to at least partially
saturate said liquid conductor; charging said electromechanical transducer to
vibrate said
perforated plate or said optional base plate; and generating a particle by
passing said liquid
through said at least one orifice formed in said perforated plate.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side elevational view of a particle generating device according to
another
embodiment of the present invention.
FIG. 2 is a side elevational view of a liquid conductor according to another
embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
DEFINITIONS :
As used herein "affixed" means that the compositions of the liquid conductor
are
permanently to semi-permanently attached such that there is a physical and/or
a chemical bond
between the compositions.
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As used herein "coherent mass" means that the compositions of the liquid
conductor are
thermally or molecularly bonded to each other such that a continuous mass is
formed where the
molecular bonds are directly formed between the molecules of the liquid
conductor.
As used herein "fluid communication" means that one structure is positioned
such that
any liquid can be transferred from that structure to another structure.
As used herein "operably connected" means any form of connection between two
or
more elements which allows the elements to perform its desired function.
As used herein "perforated plate" includes any form of plate or membrane
comprising
one or more orifices.
As used herein "plume height" means the vertical distance that a particle is
sprayed from
the perforated plate.
As used herein "series of interconnected pores" means that molecular bonds are
thermally formed throughout the liquid conductor, including to and through any
interface
between the compositions of the liquid conductor.
As used herein "vibrations" includes oscillations and other types of
deformations.
It has surprisingly been found that a device for generating particles
comprising: a
perforated plate comprising at least one orifice; an electromechanical
transducer operably
connected to said perforated plate; a liquid source comprising: a liquid
reservoir; and a liquid
conductor in fluid communication with said perforated plate and in fluid
communication with
said liquid reservoir, said liquid conductor comprising at least one open cell
composition and at
least one stiff-wick composition, wherein said compositions are affixed to one
another by
sintering, provides improved performance and is less susceptible to the
inefficiencies
encountered with conventional devices. In one embodiment, the sintered liquid
conductor is in
the form of a coherent mass comprising a series of interconnected pores
throughout the entire
liquid conductor, including any interfaces between open cell compositions
and/or stiff-wick
compositions. It is believed that this series of interconnected pores
facilitates liquid transfer
such that liquid can uniformly travel through the entire liquid conductor
without being hindered
by any physical interface or separation between the compositions of the liquid
conductor.
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1. SINTERED LIQUID CONDUCTOR
The liquid conductor of the present invention comprises at least one open cell
composition and at least one stiff-wick composition, wherein said compositions
are affixed to
one another by sintering. In one embodiment, the type of affixation is such
that said at least one
open cell composition and said at least one stiff-wick composition form a
coherent mass. Non-
limiting examples of alternative types of affixation for forming a coherent
mass between the
compositions are melt bonding, fusing, and forging. Without intending to be
bound by theory, it
is believed that a liquid conductor in the form of a coherent mass from
sintering provides
desirable benefits, including but not limited to reduced susceptibility to
inefficiencies during
operation, such as reduction of dampening effects, sufficient capillary
action, structural rigidity,
manufacturing feasibility and cost. These benefits are believed to be due in
part to the sintered
liquid conductor having distinct sections or components of differing
compositions, offering
differing physical characteristics but being in a single sintered coherent
mass. It is believed that
by sintering the liquid conductor obtains the benefits while avoiding the
disadvantages of each
type of composition as well as synergistic benefits from forming a coherent
mass.
A sintered liquid conductor can be made by the thermal treatment of a powder
or
compact at a temperature below the melting point of the main constituent so
that the powder is
heated without melting, thus increasing the number of thermal bonding sites
between the beads
and/or particles for the purpose of creating a continuous or coherent mass.
Sintering creates an
intricate network of open-celled, omni-directional pores that provide
consistency throughout the
media for a unique combination of reproducible diffusion and structural
strength. Without
intending to be bound by theory, it is believed that this network of open-
celled, omni-
directionally pores enhance the ability of the sintered liquid conductor to
transport fluid through
capillary action. In comparison to liquid conductors which may have multi-
components which
are merely adjacent to each other, the sintered liquid conductor of the
present invention allows
for continuous transfer of liquid throughout the entire liquid conductor. In
addition, the sintered
process may increase the structural stability of the open cell material by
providing binding sites
between the open cell composition and the stiff-wick composition and in such a
way increasing
the structural stability of the open cell material by taking advantage of the
stronger binding
strength of the stiff-wick material. Fluid conductors wherein the two
components are separately
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manufactured, then later manually or mechanically assembled together such as
by adhering by
adhesive or embedded, are more susceptible to coming apart or separate.
It is believed that a sintered liquid conductor provides many advantages,
including, but
are not limited to: manufacturing ease since the sintered liquid conductor can
be formed in a
single molded shape, not requiring separate manual or mechanical assembly of
separate
components; simplicity of the supply chain compared to known multi-component
liquid
conductors which involve a separate step of manually or mechanically aligning
then attaching
the separate components, wherein the sintering approach both component open
and stiff-wick are
manufactured together in a step of sintering; enhanced liquid transport to and
through the
compositions; improved structural rigidity; and performance benefits such as:
self priming
capabilities; reduction of air entrainment, that can stop emission or cause
misfiring; reduce the
tendency of flooding, due to the improved capability of the open cell fluid to
adequately
distribute the emitting fluid uniformly throughout its surface like a
manifold, in addition to the
ability of the open cell material to prevent the onset of flooding, due to the
ability of the open
cell material to contain the fluid without over wicking which can occur by the
over compression
of a stiff-wick material. It is believed that sintering provides a simplified
assembly process
wherein the entire liquid conductor can be formed within the same molding
structure, whereas
non-sintered liquid conductors may need to have each component or composition
formed
separately, requiring additional steps to attach and form the liquid
conductor.
Additionally, without intending to be bound by theory, it is believed that
sintering said at
least one open cell composition and said at least one stiff-wick composition
provides for
enhanced liquid transport between the compositions and through the entire
liquid conductor. It
is believed that the coherent mass created by the sintering process
facilitates liquid transport
because the entire liquid conductor forms a series of interconnected pores.
Without intending to
be bound by theory, it is believed that this series of interconnected pores
facilitate liquid transfer
such that the liquid can climb through the cells and pores or each component,
as well as through
any interfaces between compositions. Further, it is believed that liquid
transport is suitably
efficient because the liquid conductor is essentially free of any physical
separation (such as
adhesives) between the compositions; so liquid can now travel through a single
coherent mass,
as opposed to traveling from one composition to and through a second
composition.
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Moreover, it is believed that the sintered liquid conductor maintain its
structural rigidity
and integrity in light of repeated operation of the device. Further, it is
believed that a sintered
liquid conductor is structurally more stable. Sintering allows for increased
bonding sites on a
molecular level. Where the liquid conductor is not sintered, vibration or
deformation of the
perforated plate may cause excessive wear and tear and deformation of a liquid
conductor. It is
also believed that this sintered liquid conductor will be less susceptible to
wear and tear.
A. Affixed by Sintering
The liquid conductor of the present invention comprises at least one open cell
composition and at least one stiff-wick composition, wherein said compositions
are affixed to
one another by sintering. In one embodiment, the type of affixation is such
that said at least one
open cell composition and said at least one stiff-wick composition form a
coherent mass. Non-
limiting examples of alternative types of affixation for forming a coherent
mass between the
compositions are melt bonding, fusing, and forging. Without intending to be
bound by theory, it
is believed that a liquid conductor in the form of a coherent mass from
sintering provides
desirable benefits, including but not limited to reduced susceptibility to
inefficiencies during
operation, such as reduction of dampening effects, sufficient capillary
action, structural rigidity,
manufacturing feasibility and cost. These benefits are believed to be due in
part to the sintered
liquid conductor having distinct sections or components of differing
compositions, offering
differing physical characteristics but being in a single sintered coherent
mass. It is believed that
by sintering the liquid conductor obtains the benefits while avoiding the
disadvantages of each
type of composition as well as synergistic benefits from forming a coherent
mass.
A sintered liquid conductor can be made by the thermal treatment of a powder
or
compact at a temperature below the melting point of the main constituent so
that the powder is
heated without melting, thus increasing the number of thermal bonding sites
between the beads
and/or particles for the purpose of creating a continuous or coherent mass.
Sintering creates an
intricate network of open-celled, onmi-directional pores that provide
consistency throughout the
media for a unique combination of reproducible diffusion and structural
strength. Without
intending to be bound by theory, it is believed that this network of open-
celled, omni-
directionally pores enhance the ability of the sintered liquid conductor to
transport fluid through
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capillary action. In comparison to liquid conductors which may have multi-
components which
are merely adjacent to each other, the sintered liquid conductor of the
present invention allows
for continuous transfer of liquid throughout the entire liquid conductor.
It is believed that a sintered liquid conductor provides many advantages,
including, but
are not limited to: manufacturing ease and simplified assembly; enhanced
liquid transport to and
through the compositions; and sufficient structural rigidity. It is believed
that sintering provides
a simplified assembly process wherein the entire liquid conductor can be
formed within the same
molding structure, whereas non-sintered liquid conductors may need to have
each component or
composition formed separately, requiring additional steps to attach and form
the liquid
conductor.
Additionally, without intending to be bound by theory, it is believed that
sintering said at
least one open cell composition and said at least one stiff-wick composition
provides for
enhanced liquid transport between the compositions and through the entire
liquid conductor. It
is believed that the coherent mass created by the sintering process
facilitates liquid transport
because the entire liquid conductor forms a series of interconnected pores.
Without intending to
be bound by theory, it is believed that this series of interconnected pores
facilitate liquid transfer
such that the liquid can climb through the cells and pores or each component,
as well as through
any interfaces between compositions. Further, it is believed that liquid
transport is suitably
efficient because the liquid conductor is essentially free of any physical
separation (such as
adhesives) between the compositions; so liquid can now travel through a single
coherent mass,
as opposed to traveling from one composition to and through a second
composition.
Moreover, it is believed that the sintered liquid conductor maintain its
structural rigidity
and integrity in light of repeated operation of the device. Further, it is
believed that a sintered
liquid conductor is structurally more stable. Sintering allows for increased
bonding sites on a
molecular level. Where the liquid conductor is not sintered, vibration or
deformation of the
perforated plate may cause excessive wear and tear and deformation of a liquid
conductor. It is
also believed that this sintered liquid conductor will be less susceptible to
wear and tear.
Sintering is a processing technique well known in the art. Any method of
thermal
treatment capable of forming bonding sites between beads and/or particles
resulting in a coherent
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mass without reaching the melting point of the compositions can be used in the
present
invention. See e.g. U.S. Pat. No. 4,142,956 and U.S. Pat. No. 3,642,970.
B. At least one open cell compositions
The liquid conductor of the present invention comprises at least one open cell
composition. Non-limiting examples of suitable open cell compositions are
described in U.S.
Pat. Nos. 4,142,956, 5,451,452, and 5,506,035.
The liquid conductor of the present invention comprising at least one open
cell
composition and the stiff-wick composition is manufactured by providing both
the open cell
composition and the stiff-wick composition together in a mold with the desired
shape. The open
cell composition is added as a first component such that it is will form one
end of the liquid
conductor. The stiff-wick composition is then added to form the other end of
the liquid
conductor. The components are then sintered as described herein forming the
sintered wick.
In one embodiment, said at least one open cell composition comprises a polymer
composition. Non-limiting examples of suitable polymer compositions include:
thermoplastic
elastomer; thermoplastic vulcanizate; thermoplastic polyurethane; ethyl-vinyl
acetate copolymer
resins; and mixtures thereof. Non-limiting examples of commercially available
open cell
compositions include: thermoplastic elastomer, such as thermoplastic
vulcanizate in the form of
Santoprene 8211-75 and Santoprene 8211-55, supplied by Advanced Elastomer
Systems of
Akron, OH; thermoplastic polyurethane, such as Texin DP7-1197, Texin 970U,
or Texin
985U supplied by Bayer MaterialScience LLC of Pittsburg, PA; or ethyl-vinyl
acetate copolymer
resins, such as Elvax 3165, supplied by DuPont of Wilmington, DE.
Open cell compositions Physical Properties:
In one embodiment, said at lest one open cell composition comprises a modulus
of
elasticity of less than about 3.5 N/mm, alternatively less than about 3 N/mm,
alternatively less
than about 2 N/mm, alternatively less than about 1 N/mm. In another embodiment
of the present
invention, said at lest one open cell composition may comprise a modulus of
elasticity from
about 0.06 N/mm to about 1 N/mm. The modulus of elasticity is calculated by
the modulus of
elasticity calculation method disclosed herein.
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In one embodiment of the present invention, said at lest one open cell
composition
comprises at least one pore comprising a pore diameter ranging from about 10
microns to about
250 micron, alternatively from about 50 microns to about 200 microns,
alternatively from about
100 microns to about 150 microns. Pore diameter is calculated based on Mercury
Intrusion data.
In one embodiment, said at lest one open cell composition comprises a density
ranging
from about 0.12 g/cm3 to about 0.6 g/cm3, alternatively from about 0.25 g/cm3
to about 0.5
g/cm3.
In one embodiment, void volume percent where from about 25% to about 85%,
alternatively from 40% to about 80%, alternatively from about 50% to about
75%, wherein void
volume percent measures the portion of the composition which is void or empty.
C. At least one stiff-wick compositions
The liquid conductor of the present invention comprises at least one stiff-
wick
composition. As used herein, stiff-wick compositions include any conventional
wick material
known in the art having a modulus of elasticity greater than about 1 N/mm. Non-
limiting
examples of suitable stiff-wick compositions, and processes for making such,
include those
disclosed in U.S. Pat. No. 4,301,093, U.S. Pat. No. 6,293,474, and U.S. Pat.
No. 7,017,829.
Stiff-wick Compositions Physical Properties:
The stiff-wick composition comprises a modulus of elasticity from about 1 N/mm
to
about 200 N/mm, alternatively from about 2 N/mm to about 100 N/mm,
alternatively 3.5 N/mm
to about 100 N/mm. In another embodiment, the stiff-wick composition comprises
a modulus of
elasticity which is greater than the modulus of elasticity of the open cell
composition.
In one embodiment, the stiff-wick composition comprises at least one pore
comprising a
pore diameter ranging from about 20 microns to about 70 microns, alternatively
from about 30
microns to about 60 microns, alternatively from about 40 microns to about 50
microns. In
another embodiment, the stiff-wick composition comprises a plurality of pores
comprising an
average pore diameter from about 5 microns to about 500 microns, alternatively
from 50 microns
to about 500 microns, alternatively from about 150 microns to about 500
microns.
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In one embodiment, the stiff-wick composition comprises a void volume percent
from
about 20% to about 70%, alternatively from 20% to about 60%, alternatively
from about 40% to
about 50%, wherein void volume percent measures the portion of the composition
which is void.
Non-limiting examples of suitable stiff-wick compositions include
polyethylene,
polypropylene, ethyl vinyl acetate, polyethersulfone, polyvinylidene fluoride,
polytetrafluroethylene, polyethersulfone, and mixtures thereof.
D. Modulus of Elasticity Calculation Method
The modulus of elasticity can be determined according to the following
methodology:
An INSTRONO Model 4502 is used for this method (herein referred to as the
"INSTRON",
commercially available from Instron Corporation, Canton, MA, U.S.A.). The
INSTRON is
capable of accurately measuring a force resultant to a given change in
distance or displacement.
The INSTRON is calibrated prior to load measurement by attaching the
appropriate load cell to
the INSTRON. The appropriate load cell is determined based on the expected
data ranges.
The INSTRON is run in dynamic compression mode at about 25 C and atmospheric
pressure with a 10 kN load cell for force measurement. Test samples have the
same length and
diameter. The test sample is placed on the stationary lower platen, and the
moveable upper
platen is adjusted such that the upper platen is in contact with the test
sample but exerts no
measurable force. The upper platen is then actuated, whereby the upper platen
is lowered
incrementally to compress the sample. Measurements of force and position are
recorded. This is
repeated until the either the force measurements spiked indicating that the
maximum
compression had been achieved or the sample was observed to bend resulting in
a lowered force
measurement. As compression increases, the measurement of force should
increase.
A linear regression of the distance versus force data is then made with
distance being
measured on the X-axis and force being measured on the Y-axis. The slope of
the line, M is
thereby deterniined. Modulus of elasticity, E, is then calculated in N/mm,
from the equation: M
= E*Ao/Lo. As such,
E = M*Lo/Ao,
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where Ao is the surface area (mm2), and Lo is the initial length (mm) of the
sample.
E. Volume % of the Liquid Conductor
In one embodiment, the liquid conductor comprises from about 1% to about 49%,
alternatively from about 2% to about 30%, alternatively from about 2 Io to
about 10% of said at
least one open cell composition by volume of the liquid conductor. In another
embodiment, the
liquid conductor comprises from about 51% to about 99%, alternatively from
about 70% to
about 98%, alternatively from about 90% to about 98% of said at least one
stiff-wick
composition by volume of the liquid conductor. As defined herein, "volume of
the liquid
conductor" means the volume occupied by a solid structure having the same
outer dimensions as
the liquid conductor. It will be obvious to those of ordinary skill in the art
how to calculate and
determine this volume.
In one embodiment of the present invention, the liquid conductor comprises a
cylindrical
shape. One method to calculate the volume of the liquid conductor is to
calculate the column
volume is defined as the geometric volume of the part of the conductor which
contains the
component materials: Vc = Ac*L, where Vc is column volume, Ac is the cross-
sectional area of
the liquid conductor, and L is the length of the liquid conductor. As shown in
FIG. 3, suitable
liquid conductors may have varying cross-sectional areas and lengths. Where
the liquid
conductor has varying shapes, the volume of each section can be calculated and
aggregated to get
total volume. In another embodiment, the liquid conductor comprises any shape
which allows
the liquid conductor to draw a liquid from the liquid reservoir to the
perforated plate.
F. Separate components
Those of ordinary skill will recognize that said at least one open cell
composition and
said at least one stiff-wick composition can be present in the liquid
conductor as two, three or
more than three separate but affixed components without departing from the
scope of the
invention. In one embodiment, said liquid conductor comprises a perforated
plate facing
component comprising either said at least one open cell composition or said at
least one stiff-
wick composition. In another embodiment, said liquid conductor comprises a
liquid reservoir
facing component comprises either said at least one open cell composition or
said at least one
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stiff-wick composition. Without intending to be bound by theory, it is
believed that providing
said open cell composition and said stiff-wick compositions in separate but
sintered components
allows the liquid conductor to surprisingly and unexpectedly possess varying
physical properties
which had otherwise been exclusive of one another, i.e. the liquid conductor
is soft and
compliant while being structurally rigid and having good liquid transport
capabilities.
One embodiment of the invention comprising: a perforated plate facing
component
selected from the group consisting of said at least one open cell composition
and said at least one
stiff-wick composition; and a liquid reservoir facing component selected from
the group
consisting of said at least one open cell composition and said at least one
stiff-wick composition.
In another embodiment, the liquid conductor further comprises a third
component located
between said other two components, wherein said perforated plate facing
component and said
liquid reservoir facing component comprising said at least one, alternatively
more than one, stiff-
wick composition, and said third component comprises said at least one open
cell composition.
G. Compression Area of the Liquid Conductor
In one embodiment, the perforated plate facing component of the liquid
conductor further
comprises a compression area which is adjacent to or in the vicinity of the
perforated plate. In
one embodiment, said compression area is composed of said at least one open
cell composition.
It is believed that when the perforated plate comes into contact with the
liquid conductor of this
embodiment, the compression area will deform and undergo compression.
In one embodiment, the compression area has the same or a smaller cross-
sectional area
as the remainder of the liquid conductor. It is believed that providing a
compression area having
a smaller cross-sectional area compared to the remainder of the liquid
conductor minimizes any
dampening effects where direct contact with the perforated plate occurs. It is
further believed
that during operation, direct contact with the perforated plate causes the
compression area to
become compressed. Without intending to be bound by theory, it is believed
that the majority
of compression is localized to the compression area because the compression
area, being
composed of an open cell material component and having a smaller volume
compared to the
remainder of the liquid conductor, provides less resistance to compression.
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In one embodiment of the present invention, the compression area has a surface
facing
the perforated plate which is generally planar to the perforated plate. In
another embodiment,
this surface of the compression area comprises an uneven surface, e.g. a
depression, a ridge, a
groove, a channel, a corrugated surface, or an otherwise non-planar structure.
II. LIQUID SOURCE
The liquid source of the present invention comprises: a liquid reservoir and a
liquid
conductor. The liquid conductor is in fluid communication with said perforated
plate and in
fluid communication with said liquid reservoir. In one embodiment, the form of
fluid
communication between said perforated plate and said liquid conductor is
accomplished by
placing the liquid conductor is in the vicinity of the rear face of the
perforated plate such that
liquid transported up to the open cell composition portion of the liquid
conductor is in contact
with the rear face of the perforated plate. In one embodiment, the liquid
conductor is in direct
contact with the rear face of the perforated plate. These embodiments are
suitable for devices
comprising a coupled electromechanical transducer and perforated plate.
In another embodiment, the form of fluid communication between the perforated
plate
and the liquid conductor is accomplished by supplying liquid from the liquid
conductor into a
space formed between the rear face of the perforated plate and a base plate
which is separated
from said perforated plate by a space suitable for accommodating a volume of
liquid. Liquid is
transported from the liquid conductor into the space, either by traveling
laterally into the space,
or by traveling through one or more orifices or apertures formed in the base
plate to allow the
liquid conductor to access the space. In one embodiment, the liquid conductor
is positioned such
that a portion of the liquid conductor is present in the space. These
embodiments are suitable for
devices comprising a decoupled electromechanical transducer and perforated
plate.
III. PERFORATED PLATE
The device of the present invention further comprises a perforated plate. The
perforated
plate comprises any material capable of accepting a liquid from a liquid
source and producing a
particle. Non-limiting examples of suitable materials include: electroplated
nickel cobalt;
nickel, electro-formed nickel, magnesium-zirconium alloy, stainless steel,
other metals, other
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metal alloys, coniposites, etched silicon, plastics, and mixtures or
combinations thereof. Further,
the perforated plate comprises a frontal face and a rear face, wherein the
frontal face is oriented
to project particles away from the device and the rear face is oriented to
face the liquid as
supplied by the liquid source via the liquid conductor.
The perforated plate of the present invention comprises at least one orifice.
In one
embodiment, the orifice comprises an orifice cross sectional area from about
25 microns2 to
about 8000 microns2, alternatively from about 100 microns2 to about 6000
microns2,
alternatively from about 500 microns2 to about 3000 micronsZ. The orifice can
be in any shape
suitable to generate a particle including cylinders, squares, rectangles,
pyramid, and cones.
In one embodiment, the orifice comprises a conical shape the cone shaped
orifice can be
oriented with the smaller cross section facing the liquid conductor or away
from the liquid
conductor.. Non-limiting examples of suitable perforated plates comprising
orifices comprising
a conical shape include U.S. Pat. Nos. 5,152,456 and 5,261,601; and WO Publ.
No. 94/09912.
In another embodiment, the perforated plate comprises a plurality of orifices.
Where the
perforated plate comprises a plurality of orifices, the plurality of orifices
can be arranged in any
pattern which allows for the generation and projection of particles such as a
random pattern, a
uniform pattern, such as a hexagonal lattice, or a combination thereof. Non-
limiting examples of
suitable perforated plates include those disclosed in U.S. Pat. Nos.
4,533,082; 4,605,167;
4,530,464; 4,632,311; 6,293,474; and 7,490,815.
IV. ELECTROMECIIANICAI. TRANSDUCER
The device of the present invention further comprises an electromechanical
transducer
operably connected to either the perforated plate when the electromechanical
transducer and the
perforated plate are in a coupled configuration or to the optional base plate,
where the
electromechanical transducer and perforated plate are in a decoupled
configuration.
Electromechanical transducers according to the present invention can be made
of any material
capable of converting electrical energy to mechanical energy. Examples of
suitable
electromechanical materials include but are not limited to piezoelectric
materials and
piezoelectric ceramic materials. The use of electromechanical transducers
comprising
piezoelectric materials for generating particles is known in the art.
Accordingly, the
CA 02692284 2009-12-24
electromechanical transducer will not be described in detail except to say
that when alternating
voltages are applied to the opposite upper and lower sides of the
electromechanical transducer,
these voltages produce electrical fields which cause the electromechanical
transducer to expand
or contract in radial directions. This expansion or contraction is
comniunicated to the perforated
plate causing it to vibrate such that a pressure is exerted upon the liquid
supplied by the liquid
conductor. As such, particles are generated when liquid is forced into and
through the orifice(s)
of the perforated plate.
In a coupled embodinient, the electromechanical transducer is operably
connected to the
perforated plate such that when the electromechanical transducer is actuated,
it vibrates or
otherwise deforms the perforated plate. The vibration or deformation of the
perforated plate is
then transferred to the liquid provide from the liquid conductor forcing a
volume of the liquid
active material to be introduced into and through the orifice formed in the
perforated plate. Non-
limiting examples of devices comprising electromechanical transducers which
are disclosed in
coupled configurations wherein the electromechanical transducer is operably
connected to the
perforated plate, include those disclosed in U.S. Pat. Nos. 4,533,082;
4,605,167; 4,530,464
4,632,311, 7,017,829 and 7,490,815.
In another embodiment, the device comprises an electromechanical transducer
which is
in a decoupled configuration from said perforated plate. In this embodiment,
the device
comprises said perforated plate, positioned to emit the liquid particle away
from the device, and
a base plate which is positioned below on the side of the rear face of said
perforated plate such
that a space between the plates is formed. Liquid is supplied to the space
between said
perforated plate and said base plate either by flowing laterally from the
liquid conductor into the
space or through an orifice or aperture formed in the base plate which allows
the liquid
conductor to pass the liquid into the space. The electromechanical transducer
is then operably
connected to the base plate. When actuated, the electromechanical transducer
causes the base
plate to vibrate or otherwise deform. The vibration or deformation is
transferred into the liquid
contained with the space, forcing a volume of liquid to enter the orifice
formed in the perforated
plate resulting in the emission of a liquid particle from the device. Non-
limiting examples of
devices comprising electromechanical transducers which are in a decoupled
configuration with
the perforated plate, wherein the device comprises a perforated plate
positioned to emit particles
CA 02692284 2009-12-24
16
into the atmosphere, away from the device, and a base plate, are provided in
WO 2007/062698 to
Hess et al.; see, also, U.S. Patent Nos. 6,196,219 and 6,405,934 both to Hess
et al.; and U.S.
Patent No. 2005/0230495 to Feriani et al.
V. LIOUID ACTIVE MATERIALS
The device of the present invention is capable of generating particles from a
liquid
coniprising at least one liquid active material. In one embodinient, the
liquid comprises two or
more liquid active materials. In another embodiment, the device comprises more
than one liquid
source, wherein each liquid source comprises at least one liquid active
material. By providing
niore than one liquid source, liquid active materials which are preferably
stored away from one
another or are otherwise incompatible can be stored in separate liquid
sources.
Liquid active materials suitable for use with the present invention coinprise
perfumes, air
fresheners, deodorizers, odor eliminators, malodor counteractants, household
cleaners,
disinfectants, sanitizers, repellants, insecticide formulations, mood
enhancers, aroma therapy
formulations, therapeutic liquids, medicinal substances, or mixtures thereof.
Non-limiting
examples of suitable liquid active include those disclosed in U.S. Patent No.
7,490,815.
VI. REFILL DELIVERY APPL,ICATIONS
In refill delivery systems applications, it is be desirable to separate the
unit into two or
more parts. One embodiment of the present invention provides for a refill
system comprising the
liquid source and a refill volume of liquid. In another embodiment, the refill
system comprises
all elements of the device other than the liquid source. In another embodiment
of the invention
the refill system comprises the liquid source, a refill volume of liquid, the
electromechanical
transducer, and the perforated plate. The reusable components may then
comprise a device
housing, the drive electronics and a power source.
VII. OPERATION OF THE DEVICE
During operation, liquid is supplied to the rear face of the perforated plate
from the liquid
source via the liquid conductor. The device can be a coupled or decoupled
configuration.
Where it is coupled, the perforated plate is then vibrated by the
electromechanical transducer
wherein a resultant pressure is believed to be exerted on the liquid. This
pressure is believed to
CA 02692284 2009-12-24
17
cause aniounts of the liquid to be forced into the at least one orifice at the
rear face of the
perforated plate thereby forming a particle. Moreover, the pressure is
believed to then cause the
particle to be projected out of the front face of the perforated plate, away
from the device. Those
of skill in the art will understand that the liquid conductor of the present
invention can also be
used on decoupled electromechanical transducers as described herein.
The device in operation can be driven in many different modes including a
continuous
sine wave mode, other continuous modes, a single pulse mode, trains of pulses,
single
synthesized waveforms, trains of synthesized waveforms, or other modes known
in the art.
Modes of operating atomizing devices are well known and are disclosed in U.S.
Patent No.
7,490,815.
In a process aspect of the present invention, there is provided a method for
generating a
particle comprising the steps of: providing a device according to the present
invention wherein
said device contains a liquid; conducting a liquid from the liquid reservoir
to at least partially
saturate the liquid conductor; charging the electromechanical transducer to
vibrate the perforated
plate; and generating a particle by passing said liquid through said at least
one orifice of the
perforated plate.
The present invention provided surprising and unexpected results during
operation.
Indeed, the present invention was capable of operating at compression levels
beyond what has
been possible from the known art. It has surprising been found that devices
according to the
present invention are capable of generating and projecting particles even
during high liquid
conductor conipression, wherein one of said devices were capable of generating
and projecting a
particle with an average plume height of from 10 cm to about 30 cm in the
presence of high
conipression. As used herein, high liquid conductor compression means
compression point
compressions beyond about 10 % by volume, alternatively from about 10% to
about 30% by
volume. It is believed that conventional devices are not capable of generating
and projecting
particles at an average plume height of at least 10 cm where the compression
point is
compressed more than 10 % by volume. As such, it is believed that the present
invention
provides a device which is less susceptible to dampening effects.
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18
DRAWINGS
FIG. 1 illustrates the relationship between the liquid source 30 (comprising
the liquid
conductor 50, and the liquid reservoir 40), the perforated plate 10, and the
electromechanical
transducer 20.
FIG. 2 illustrates the general relationship between the perforated plate
facing component
being at least one open cell composition 55, and the liquid reservoir facing
component being at
least one stiff-wick composition 52 of liquid conductors according to the
present invention.
Further, in this embodiment, the liquid conductor 50, comprises a compression
area 58. Those
of ordinary skill will recognize that the compositions (as well as the
components in this case) are
affixed by sintering such that the liquid conductor forms a coherent mass
throughout, including
at the interface of the compositions.
EXAMPLE I:
The modulus of elasticity of the following examples were determined in
accordance with
the modulus of elasticity calculation method described above.
Pore Pore Modulus of Standard of Number of
Size Volume Elasticity Dev. Samples
(N/mm)
Liquid Conductor A 32 32 60.55 5.52 3
Liquid Conductor B 32 46 30.22 1.71 3
Liquid Conductor C 27 61 6.7 1.90 3
Liquid Conductor D NA NA 4.67 0.80 9
Liquid Conductor E 69 72 2.41 1.14 3
Liquid Conductor F 1.5 3
Perforated plate 30 50 0.42
facing component
Liquid reservoir 32 46 30.0
facing component
Liquid Conductor G NA NA 0.03 0.03 2
Liquid Conductor A-D: Single component conductors composed of polyethylene.
Liquid Conductor E: Single component conductor composed of open cell, ether.
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WO 2009/001319 PCT/IB2008/052581
19
Liquid Conductor F: Sintered liquid conductor, perforated plate facing
component
composed of thermoplastic vulcanizate, liquid reservoir facing component
composed of
polyethylene.
Liquid Conductor G: Single component conductor composed of Open Cell Material,
reticulated polyester polyurethane with a density of -55 kg per cubic meter.
The pore size or the pore volume for Samples D and G could not be measured.
Liquid conductors A-D fail to provide sufficient softness as measured by the
modulus of
elasticity. Liquid conductor F provides sufficient softness and compliance,
structural rigidity,
along with good liquid transport capabilities. Liquid conductors E and G also
provides sufficient
softness but insufficient structural rigidity and liquid transport.
EXAMPLE II
The following example is intended as a demonstration of the surprising results
observed
during operation of the present invention. One non-limiting example of an
observed benefit is
that the present invention is capable of operating with acceptable performance
in the presence of
increased compression of the liquid conductor. The following data was
collected using a liquid
conductor from Samples C and F from Example I. Compression was measured as
displacement
and then calculated as volume % compression of the compression areas of the
liquid conductors.
Volume % compression and plume height were calculated according to the method
below.
Table A captures the average plume height of a projected particle during
operation of a
device comprising the liquid conductor of Example F, with a compression area
having a height
of about 4.6 mm and a diameter of about 2 mm. It has been found that devices
according to the
present invention are capable of generating an average plume height of greater
than about 10 cm
even during compression of at least about 10%, alternatively from about 10% to
about 30% of
the compression area.
Table B captures the average plume height of a projected particle during
operation of a
device comprising the liquid conductor of Example C, with a compression area
having a height
of about 4.6 mm and a diameter of about 2 mm. Devices providing average plume
height of less
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WO 2009/001319 PCT/IB2008/052581
than about 10 cm with compression greater than or equal to about 10% of the
compression area
are not within the scope of the present invention.
For simplicity of analysis, it will be assumed that all liquid conductor
compression is
localized to the compression area and that any compression occurring in the
remainder of the
liquid conductor is negligible. Further, in calculating the amount or volume
of compression, it
will be assumed that any horizontal deformation of the compression area is
minimal. As such,
any change in the height of the compression area will provide a direct
correlation to change in
the volume of the compression area. Thus, a Io change in height can be
interpreted as a volume
Table A: Compression vs. Plume Height for a device with Liquid Compressor F.
Displacement Plume Plume Plume Plume vg. Plume
(scaled) Volume % Height (1) Height (2) Height (3) Height (4) eight
(mm) Compression (cm) (cm) (cm) (cm) (cm)
0.000 0.000 9 9 13 12 10.75
0.328 7.130 11 12 10 12 11.25
0.362 7.870 12 10 11 11 11.00
0.428 9.304 11 10 11 11 10.75
0.491 10.674 11 11 12 11 11.25
0.559 12.152 10 10 11 11 10.50
0.635 13.804 12 12 12 11 11.75
0.745 16.196 11 11 12 11 11.25
0.893 19.413 12 12 11 12 11.75
1.050 22.826 13 11 12 11 11.75
1.266 27.522 11 10 11 11 10.75
1.445 31.413 11 11 11 11 11.00
1.634 35.522 10 10 10 10 10.00
1.913 41.587 9 9 8 8 8.50
2.089 45.413 8 9 9 9 8.75
Table B: Compression vs. Plume Height for device with Liquid Conductor C.
Displacement Plume Plume Plume Plume
(scaled) Volume % Height Height (2) Height (3) Height vg. Plume
(mm) Compression (1) (cm) (cm) (cm) (4) (cm) eight (cm)
0.000 0.000 8 9 10 10 9.25
0.120 2.609 11 12 12 12 11.75
0.168 3.652 12 12 12 11 11.75
0.178 3.870 11 11 12 11 11.25
0.210 4.565 13 12 11 11 11.75
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WO 2009/001319 PCT/IB2008/052581
21
0.356 7.739 11 11 12 11 11.25
0.440 9.565 8 9 8 7 8.00
0.500 10.870 8 9 7 8 8.00
0.810 17.609 5 4 5 5 4.75
1.070 23.261 4 4 4 5 4.25
1.120 24.348 4 3 4 3 3.50
1.330 28.913 no spray no spray no spray no spray
1.780 38.696 no s ra no s ra no s ra no s ra
1.950 42.391 no spray no spray no spray no spray
2.070 45.000 no spray no spray no spray no spray
COMPRESSION AND PLUME HEIGHT DETERMINATION CALCULATION METHOD
An INSTRONO Model 4502 is used for this method (herein referred to as the
"INSTRON", commercially available from Instron Corp., Canton, MA, U.S.A.). The
INSTRON
is run in dynamic compression mode with a 10 kN load cell for force
measurement. The upper
platen moves, and the lower platen is stationary. The test samples chosen for
the
characterization are cut to the test specific determination and manually
inserted into a liquid feed
element.
Compression measurements of a test sample are conducted at a temperature of 25
C
measured in accordance with techniques which will be quite well-known to those
of ordinary
skill. The INSTRON is the equipment utilized for these measurements due to its
capability of
accurately measuring a given change in distance or displacement. The INSTRON
is calibrated
prior to load measurement following the procedure described before. The test
sample is placed
on the lower platen, and the upper platen is adjusted such that the upper
platen is in contact with
the sample but exerts no measurable force. The upper platen is then actuated.
The platen is
lowered near the top of the sample and its position is recorded. The platen is
lowered
incrementally to compress the sample and each position measurement is
recorded.
Simultaneously the perforated plate is triggered to start atomization. A scale
divided in
centimeters is placed in the front face of the perforated plate and
measurements were taken along
the centerline of the spray to determine the plume height. The plume height is
the highest point
where particles are seen to leave a residue or marking on the scale. This is
repeated until the
sample is compressed to about 2 mm or about 50 % compression is achieved. The
data are then
reported as volume % compression versus plume height.
CA 02692284 2009-12-24
22
It should be understood that every maximum numerical limitation given
throughout this
specification includes every lower numerical limitation, as if such lower
numerical limitations
were expressly written herein. Every minimum numerical limitation given
throughout this
specification includes every higher numerical limitation, as if such higher
nuinerical limitations
were expressly written herein. Every numerical range given throughout this
specification
includes every narrower numerical range that falls within such broader
numerical range, as if
such narrower numerical ranges were all expressly written herein.
All parts, ratios, and percentages herein, in the Specification, Examples, and
Claims, are
by weight and all numerical limits are used with the normal degree of accuracy
afforded by the
art, unless otherwise specified.
The dimensions and values disclosed herein are not to be understood as being
strictly
limited to the exact numerical values recited. Instead, unless otherwise
specified, each such
dimension is intended to mean both the recited value and a functionally
equivalent range
surrounding that value. For example, a dimension disclosed as "40 mm" is
intended to mean
"about 40 mm".
While particular embodiments of the present invention have been illustrated
and
described, it would be obvious to those skilled in the art that various other
changes and
modifications can be made without departing from the spirit and scope of the
invention. It is
therefore intended to cover in the appended claims all such changes and
modifications that are
within the scope of this invention.
All documents cited in the Detailed Description of the Invention are.
not to be construed as an
admission that it is prior art with respect to the present invention. To the
extent that any
nieaning or defmition of a tertn in this document conflicts with any meaning
or definition of the
same term in a document cited herein, the meaning or definition assigned to
that
term in this document shall govem.
While particular embodiments of the present invention have been illustrated
and
described, it would be obvious to those skilled in the art that various other
changes and
modifications can be made without departing from the spirit and scope of the
invention. It is
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WO 2009/001319 PCT/IB2008/052581
23
therefore intended to cover in the appended claims all such changes and
modifications that are
within the scope of this invention.
