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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
resonance device and an ultrasonic transducer, and more specifically to a transducer for
efficiently generating periodic vibration having a wave number of an ultrasonic head. It is.
BACKGROUND OF THE INVENTION Piezoelectric blade blowers are known that are much smaller
than the smallest rotating fans and are used to cool electronics. These blowers are very efficient,
have a long life, generate little noise or magnetic interference, and have dimensions of about s o
5C 1 rL (2 in) x 2.54 儂 (tin) Xl, 90 cTL (% z n ), But they also have drawbacks. They are not small
enough to be attached directly to a printed circuit board, create electrical noise in the circuit
board, and require the circuit board to have a 115 volt power source available. Attempts to use
piezoelectric crystals to pump air directly by acoustic flow have also been less successful because
they require large crystals that are difficult and expensive to obtain in product form. Acoustic
flow arises from the fact that air accelerated by a vibrating surface does not reverse its direction
due to inertia and compressibility, even if the surface is reversed, and at higher amplitudes
turbulence It is further complicated by the creation of vortices. The use of ultrasonic energy to
evaporate fluids such as water is known in the art. For example, home humidifiers use a
transducer driven at ultrasonic frequencies to convert water to water vapor, which is blown into
the room by a fan to increase conductivity. It is also known to use ultrasonic energy to atomize
liquids, such as various perfumes, by applying ultrasonic energy to the core element, the core
element being an ultrasonic vibration applied to the core member from the tank. A small amount
of liquid is suitably delivered to the generated ultrasonic transducer. However, there is a need for
an improved sprayer that evaporates a liquid that is not sufficiently volatile to be easily atomized
by a conventional ultrasonic transducer. It is also desirable to create a very efficient spray device
that uses a low voltage source, such as a 9 volt battery, to atomize various perfume and other
liquids. Accordingly, it is an object of the present invention to provide an improved ultrasound
co-imaging member. It is also an object of the present invention to provide an improved small,
very efficient and high speed acoustic pump. Another object of the invention is to provide a
pump which can be mounted directly on a printed circuit board and whose dimensions are
comparable to the components to be cooled.
Another object of the invention is to provide such a pump operating at low voltage. Another
object of the present invention is to provide such a pump which operates without vibration so as
to be virtually unheard in the ultrasound range. Another object of the invention is to provide
such a pump which generates a very high air flow. Another object of the invention is to provide
such a pump with virtually unlimited service life, no magnetic interference, no heat generation
and no high starting current. Another object of the invention is to provide such a pump which
can be mounted on a printed circuit board and which is pumped parallel to the printed circuit
board. Another object of the present invention is to provide such a pump which can utilize
acoustic flow. Yet another object of the present invention is that it is particularly suitable for
atomizing liquid perfumes that are not sufficiently volatile to be easily vaporized with high
efficiency by conventional ultrasonic transducers, such as 9 volt batteries It is to provide a
sprayer using low voltage and cheap power source. [Means for solving the problem] Use a
resonance member which has small internal damping, tapers to a thin edge, and resonates in an
open knot pattern whose thin edge intersects the edge. Is based on realizing that a truly effective,
small, high speed, high volume resonant device can be made. The invention features, in one
embodiment, an acoustic air pump with a resonant member that has low internal damping and
has an asymmetrically tapered leading edge. A piezoelectric drive is attached to the resonant
member and means are provided for applying a pulsating voltage to the piezoelectric drive in the
resonant range of the resonant member to cause the resonant member to vibrate and swing the
fluid away from the thin edge. According to another embodiment, the invention features a
sprayer that converts liquid to vapor in a highly efficient manner. The liquid is delivered at a flow
rate that produces a mist of liquid on a portion of the resonant member adjacent the thin edge of
the resonant member. A battery operated voltage drive circuit generates a pulse train having a
voltage pulse of about 9 volts, which pulse train is applied to the resonating member and applied
to a thin piezoelectric element having a mass sufficiently smaller than the resonating member,
The piezoelectric element can operate at a low voltage. Preferably, the pulse train ensures that
the resonant member is driven at its resonant frequency regardless of variations in the
mechanical loading of the return resonant member at frequencies between 20 kHz and 80 kHz.
In the preferred embodiment of both the acoustic blower pump and the vaporizer, the resonant
member driven by the thin piezoelectric drive element has a Q greater than 300 and can be
either a tempered aluminum alloy, carbon steel, glass or ceramic. preferable. Preferred materials
may have Q as high as 1000 and have a high stiffness to density ratio of at least 2 x 1 o dyn-cm /
11. In the preferred embodiment, the piezoelectric drive is attached to the drive member to cause
the drive member to shoot in a cross-hatching pattern that intersects the thin edge. The nodal
line may be an open nodal pattern or may be semicircular, and may have two inflection points
near the intersection with the thin edge, separating the drive element from the thin edge The
perforated plate may be attached to the resonance member above the inflection point. The
perforated plate may also be mounted below the tapered surface and may be flat or of other
shape such as an inverted V-shaped groove. Perforated plates can also be spaced above the
tapered surface. The perforated plate is placed in a position of dynamic equilibrium between the
acoustic pressure acting away from the surface and the reaction pressure acting towards the
tapered surface. Mounting this perforated plate loosely above the tapered surface to determine
the position of the dynamic equilibrium between the acoustic pressure acting in the direction
away from the tapered surface and the reaction pressure acting towards the tapered surface It
may be possible. The resonant member may be asymmetrically tapered into two thin edges,
which may have a substantially planar cross section with the tapered portion extending out. The
piezoelectric drive can be mounted on the bottom, top or side of the resonant member. The
means for applying a pulse train may comprise one electrode on the opposite side of the
piezoelectric drive. The perforated plate can be made of metal and may contain about 42 holes
per ICa, which holes may be about 0.018 to 0.025 ffi in diameter. These holes may be formed by
substantially conical walls which converge away from the tapered surface. Other objects, features
and advantages will be derived from the following description of the preferred embodiment and
the accompanying drawings. FIG. 1 shows an acoustic pump 10 in the form of an ultrasonic fan
having a resonating member 12 with an asymmetrically tapered section 14 which becomes
thinner and thinner at the thin edge 1G. The resonant member 12 still comprises a substantially
flat section 18 (FIG. 2). A piezoelectric driver 20 is attached to the resonant member at a distance
from thin edge 6, but it operates near the thin edge.
The piezoelectric driver may be attached to the bottom as shown in FIG. 1, or 1 ft: may be
attached to one of the side surfaces 20a or to the upper surface 20aa as shown by the phantom
line in FIG. If the electrode 22 is provided on the outer surface of the piezoelectric driver 20 and
sufficiently conductive, the resonant member can act as the other electrode to apply an imaging
current to the piezoelectric driver 20 by means of the alternating current source 24. When an
oscillating current is applied, the tapered surface 26 vibrates to create an acoustic flow effect
that causes air to vibrate away from the thin edge 16 as illustrated by the compressed wave front
28. The overall dimensions of the resonant member 12 are fig 2.730 cn′L (1,075 in) wide,
3.238 CI ′ n (1,27 s 1 n) long and 0635 cm (0,2 s in) thickness or height It may be.
Piezoelectric driver 20 is a PTS-1512 piezoelectric ceramic or equivalent sold by Piezoelectric
Products, and has a thickness of 0.0254 crIL (o, o t 1 n) with a diameter of about 2.489 crf L (0,
9 s 1 n) Can be made with The piezoelectric 1 driver may be nickel plated on both sides to form a
bonding surface on one side for attachment using the electrode 22 and aluminum resonating
member 12 Helockite 404 type cement or equivalent. The amplification membrane, which is a
perforated plate 30 with holes 34 in FIG. 3, is applied by attaching the amplification membrane
to the resonant member 12 with a flexible hinge 32 so that it floats at an optimal height above
the tapered surface 26 it can. This height is a dynamic balance between the acoustic pressure
acting towards the tapered surface 26 and the reaction pressure acting towards the tapered
surface 26 when the perforated plate 30 is held loosely in place. The perforated plate is selfadjusting so that it automatically floats above the vibrating taper surface 26 until it reaches the
position of. The amplification membrane is shown above the tapered surface and is nearly flat,
but this is not a necessary limitation of the present invention. For example, the amplification
membrane may be mounted spaced from the bottom of the tapered surface or may take the form
of an inverted V-shaped groove 30 with holes 34 directed in the direction of air movement. The
flange 35 may be affixed to the tapered surface 26 ', but the perforated portion with the holes 34
may be spaced above the tapered surface as in other configurations. Although the effect of the
amplification membrane is not completely understood in detail, the levitation of the amplification
membrane is, as described, the downward pressure by the injected air and the upward pressure
by the flow of air carried under the amplification membrane. It seems to occur at a height that
just balances.
It has been found that the perforated plate 30 works well with about 42 holes per cd with a
diameter of o, 0177-0.0254 cTL (o, oo 7-0.01 in). The hole was formed by punching a center
plate of thickness o, o 5 cTL (o, o O 2 in), length 2.73 cm (1,075 x n), width 1.65 clr L (o 6 s 1 n).
Good results have been found when the punched holes 34a of FIG. 4 converge in a direction
away from the tapered surface 26 and have a conical projection 36 ending in a jagged edge 38.
The acoustic pump 10 of FIG. 1 gives good performance, but the result is even better when the
perforated plate 3o is used in combination therewith. The resonant member 12 is made of a
material having low internal damping, ie, high rQJ in the range of 300 or more, such as tempered
aluminum or magnesium alloy, carbon steel, glass or ceramic. Aluminum alloy 6061-T6 is one of
the presently preferred materials. The scaled resonant material has a stiffness to density ratio of
at least 2 x 10 dyn-cIV 'fi obtained by dividing the material's stiffness by the material's density,
eg, in the case of aluminum, this ratio has a stiffness ratio of 0 It is obtained by dividing .7 x 10
dyn / m by the density of aluminum 2, 7 J / cyd Using an aluminum alloy 2024 T-561 coimaging member powered by a first harmonic with a 34 kHz square wave and a power supply of
12 port tip values, the blower consumes 1.3 watts of power, 144. A significant temperature rise
(o, o s s 6 rr // m 1 n (2 rt / familiar) air with an average speed of 7 syy + / m (47 s ft / i) and a
maximum speed of 426.7 zm / mm (1400 rt / m 1 yt) Send out the flow of Under these
conditions, the perforated plate 30 floats at a height o o 76 scm (o o sin) above the tapered
surface 26. When the levitation height is known, the plate 30a of FIG. 5 is fixed by clamping in
place to the appropriate mount at which the mount is held in place as shown on the pedestal
40.42. Or the same method as holding the plate 30a in a mount which only encloses the edge of
the perforated plate 30a loosely and the height of the plate is made possible by the flexible hinge
32 of FIG. Can be adjusted automatically. The present invention preferably uses the knot pattern
50 of FIG. 6 which is generally circular in shape and is open at the thin edge 16 and includes an
inflection point 52.54 near the edge 16.
A perforated plate is preferably placed over the inflection point, this thin edge to create an open
knot pattern that provides high amplitude pumping action that moves air through the acoustic
flow phenomenon. It is necessary in the shape of the resonant member 12. Attach the resonant
member 12 to the printed circuit board or other environmental structure on the back side 62
away from the tapered surfaces 26 and 16 7'iJi! 60 can be attached, or it can be formed in the
form of a knurled pattern 50 and is in FIG. 7 such as a semi-circular rubber element glued to the
underside of the resonant member 12 below the knurled pattern It may be attached by using a
knot pattern support 70. The resonant member 12 is not limited to the specific shape shown in
FIGS. 1 and 2. For example, it may be tapered towards the thin edge 16a of FIG. 9 and have the
generally oval shape 12a of FIG. 8 which provides the same type of knot pattern 50a when
having the same type of surface 26a. Elliptical resonant member 12a of FIG. 9 does not have an
extra generally flat section 18, but includes only tapered portion 14a. The elliptical resonance
member 12a has a major axis of 3.429 CTL (1, 3 s in) and a minor axis of 3.175 c7 rL (1, 2 s tn)
with a thickness of 0.3175 CTL (0, 125 in). Good. The resonant member is not limited to a single
thin edge and a tapered surface, for example, as shown in FIG. 10, the resonant member 12b is a
flat section having two tapered surfaces 261) and 26bb ending in thin edges 16b and 16bb.
Alternatively, it may be provided with a thick plate 18b, which can be used for similar acoustic
bonding using similar acoustic techniques. FIG. 11 shows an embodiment of the present
invention in which the liquid 72 contained in the container 73 is vaporized by the resonant
member 12. The core member 74 causes the liquid in the container 73 to be delivered by
capillary action applied upward to the lower portion 76 of the resonant member, which is driven
by the electronic circuit shown schematically in FIG. It is supposed to be. Most of the core
member 74 is in contact with the lower edge of the resonant member at the antinode. As
mentioned earlier, the two 50 oscillating nodes 77 and 78 in a looped pattern are present at the
lower edge of the resonant member as shown, whereby the outer portion 76 of the lower edge
portion is at maximum amplitude. Resonate. The result is the generation of a fluctuating vapor
81 which produces a wide dispersion of the vaporized liquid supplied by the core member 74, so
this device is a blower device which dispenses aroma as a liquid sprayer without the need for a
blower fan Act as.
In FIG. 12, a conventional 9 volt battery 81 is connected to a sawtooth sweep generator 83 via a
switch 82 to sweep the output frequency of the voltage controlled oscillator 84, the voltage
controlled oscillator being a complementary output solid 1 It is connected to the driver circuit or
180 phase inverter 24. The complementary outputs, leads 8G and 88 of the drive, are electrically
connected to the thin piezoelectric element 20 described above, and the piezoelectric element 20
drives the resonant member 12. Since the electronic drive circuit of FIG. 12 is used to generate a
variable frequency pulse train swept between 20 kHz and 80 kHz, there is a variation in the
resonant frequency of the resonant member 12 due to changes in load conditions. Nevertheless,
the resonant member is driven at its nominal resonant frequency at some point during the sweep
period of the sweeper 83. The driver circuit 24 is a 180-degree conversion circuit that applies
battery voltages alternately to the leads 86 and 88 in a bipolar manner, so pulses of positive +9
volts and negative 19 volts alternate on the piezoelectric element 20. In addition, a peak-to-peak
voltage swing of 18 volts is generated during each vibration cycle, and as a result the
piezoelectric drive element 20 is bent in a first direction and then bent in a second direction to
form a resonant member 12. Generates a reciprocating motion that is induced to As a driver, an
IC # 4069 BCMO3, Hex inverter was used as a driver to generate a pulse train of only 30 mA
effective. As components 24.83 and 84 are well known to those skilled in the art, the details have
not been described in order to simplify the description. Pulse gj direct current was also available.
Liquid sprayers constructed in accordance with the present invention are smaller, consume less
power, and can operate at lower voltages than conventional ultrasonic sprayers. It has been
found that the conventional 9 volt battery used as described above gives excellent results. The
volume of steam generated is mild and has successfully relied upon relatively low volatility
liquids such as water, alcohol and water-alcohol-oil mixtures, and surprisingly does not require a
blower fan. The flow of liquid applied to the resonating member need not be too large, and wicks
that use capillary action to deliver liquid to the resonating member produce good results. The
current fancy resonance member 12 has a thickness of 0.2 s 4 Crn (0, 1 in) and a length of 127
L: rft (0, 5 in) 1.27 c! It has a width of rL (0, stn) and is made of aluminum alloys 6061-T6.
Besides acting as an acoustic air blower pump to cool various devices, such as printed circuit
boards, and as a very efficient sprayer, the resonant member 12 is submerged in the wash tank
to efficiently apply ultrasonic energy to the liquid tank for washing To introduce.
Although certain features of the invention are shown in some of the drawings and others have
not, K is for convenience only as each feature may be combined with any or all of the other
features according to the invention.
Brief description of the drawings
1 is a schematic side view of an acoustic pump according to the present invention, FIG. 2 is a
plan view of a resonance member portion of the pump of FIG. 1, and FIG. 3 shows a resonance
member having an amplification membrane mounted on a tapered surface. Similar to FIG. 1, FIG.
3A is an axial projection of another form of amplification membrane, FIG. 4 is an enlarged
sectional view showing a hole in a part of the amplification membrane of FIG. 3, FIG. Fig. 6 is an
end view of a partial cross section of another mounting for a membrane, Fig. 6 is a plan view
showing the attachment technique of the resonant member and the open knot pattern created by
the resonant member, Fig. 7 is Fig. Fig. 8 is a plan view of an elliptical resonance member
showing a knot pattern, Fig. 9 is a side view of the oval member in Fig. 8, Fig. 10 Fig. 11 is a view
of a resonant member having two sections asymmetrically tapered towards a thin edge, Fig. 11 is
an atomizer constructed according to the invention Axis side projection view of a preferable
embodiment, FIG. 12 is a schematic diagram illustrating an electronic battery-operated drive
circuit for driving a piezoelectric element attached to the resonant member.
Drawing (inside; this without further) FIG, 3AFIG, 6FIG, 7F FIG8FIG 9FIG, / 2 procedures
correction (written method)% formula% 1, display of the case Showa 621 patent application No.
169953 3, Relationship with the case for correction Patent applicant 4, agent
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