JPS60193571A - Piezoelectric vibrator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Technical Field> The present invention relates to a piezoelectric vibrator using a piezoelectric vibrator made of a piezoelectric material and an electrode bonded together in order to directly convert electricity into mechanical vibration. , relates to a piezoelectric vibrating device that can be used in pressurizing parts of pumps for gases and powders and other vibrating parts.

Conventional technology> Conventionally, pumps for liquid fuel use electric motors or solenoids to operate impellers, pistons, or plungers, and their rotational or reciprocating motion applies centrifugal force to the liquid fuel and discharges it. It had a structure that discharged water by expanding and contracting the internal volume. In this conventional pump, the impeller, piston, plunger, etc. that act directly on the liquid fuel move by themselves even when an electric signal is applied.The impeller and piston transfer the rotational movement of the electric motor to the transmission shaft. The receiver and plunger perform their functions using the magnetic field (electromagnetic force) caused by the current flowing through the solenoid, but having such an intermediate transmission mechanism increases the size of the pump itself and also The internal structure was complicated.

<Prior Application Technology> In view of the above points, the applicant of the present application has simplified the structure and miniaturized the pump by using a unimorph vibrator that directly converts electrical energy into vibration, which is a reciprocating motion, in the pressurizing part of the pump. Patent application No. 1-75381 has already been filed for the pump to be obtained.
It is proposed in the issue.

The structure is as shown in FIG. 1(a)(1))(c). Shinawa%BC is a disk-shaped unimorph piezoelectric vibrator using a piezoelectric ceramic thin plate (piezo element) 2 as a vibrating part, and the inside of the pump body 3 consisting of three component pieces 3 a, 3 b, and 3 c. Expand its volume to the liquid pressurized chamber 4,
A disk-shaped unimorph resonator BC is arranged so as to be reduced in size. 5 is a metal thin plate that constitutes the unimorph vibrator BC together with the piezoelectric ceramic thin plate 2; 6 is a discharge side check valve;
a is a discharge passage, 7 is a suction side check valve, 7a is a suction passage, 6
b is a discharge side joint, 71] is a suction side joint, 8 is an annular elastic body, 9 is a conducting wire, and 10 is an annular elastic body.

In the liquid pump having the above structure, the unimorph vibrator BC
When a constant frequency voltage is applied to the conducting wire 9 connected to the unimorph resonator Bc, the unimorph resonator Bc is deformed alternately into a concave and convex shape.

Two check valves 6 and 7 are installed in front of this unimorph oscillator Bc.
, and when the unimorph oscillator BC changes into a concave shape,
The discharge side check valve 6 is closed, and the suction check valve 7 is opened and liquid fuel flows into the liquid pressurizing chamber 4.

Next, when the unimorph oscillator BC changes from a planar shape to a convex shape, the suction side check valve 7 closes, and the liquid fuel in the liquid pressurizing chamber 4 between the discharge side check valve 6 and the discharge control + ) - pumped through valve 6. In addition, the unimorph resonator BC is connected to the conductor 9.
When a voltage of a constant frequency is applied to the pump, the pump deforms into a concave and convex shape alternately, and the discharge flow rate of the pump can be controlled by the voltage.

According to the above-mentioned prior art, the following effects can be expected.

(a) The use of a unimorph resonator simplifies the function and structure, making it possible to downsize.

(b) The number of R-function parts is reduced, and the cumulative influence of shape accuracy of each part is reduced, so high quality can be expected.

(c) The conventional intermediate transmission mechanism can be omitted, and loss in this mechanism can be eliminated, resulting in high efficiency.

(d) It is inexpensive in terms of cost.

(e) Since there is no reciprocating movement, there are no quality problems due to wear and tear.

(f) The discharge amount is controlled linearly by controlling the voltage.

Further, the vibrator applied voltage control circuit in the prior art was configured as shown in FIG. 1(d).

In other words, the diode DI, l) is connected so that a constant voltage is applied to the piezoelectric vibrator BC even if the input power supply AC fluctuates.
2. Resistors R1, R2, R3, R4, capacitors CI, C
2. Constant voltage diode ZD1.2D2, transistor T
ri, Tr4 is used. And resistors R5, R6, constant voltage diode-FZD3. Obtain a constant power supply for operational amplifiers (hereinafter referred to as operational amplifiers) ICI and IC2 with ZD4, oscillate a sine wave signal with the operational amplifier, and generate AC voltage waveforms in both positive and negative directions at the 0 point as shown in Figures 2 and 3 (,). It has gained. The sine wave signal obtained by the operational amplifier is then passed through coupling capacitors C3 and C4 to transistor Tr2. Insert one base of Tr3,
2 and 3 (Fig. 2 and 3) at point d.
By obtaining the AC voltage waveform as shown in b), the piezoelectric vibrator B
Since C is repeatedly charged and discharged, distortion and vibration occur,
A pump using this piezoelectric vibrator BC operates.

In this applied voltage control circuit, the applied frequency is switched by turning on and off the photocoupler PCI, which consists of the light emitting element P1 and the light receiving element P2, by turning on and off the light emitting element P1 according to instructions from the microcomputer. , only when the photocoupler PC1 is on, the control resistor R is inserted in parallel with the variable resistor VR, and their combined resistance becomes small, and the input signal of the operational amplifier ICI changes, so the voltage waveform at point d becomes the second As shown in FIG. 3(1)), the frequency is higher than in FIG. 3(1)) when the photocoupler PC4 is off. In other words, in the case of strong operation that requires a large discharge amount, the photocoupler PC1 is turned on, and the voltage waveform at the 0 point on the output side of the operational amplifier C2 and the voltage at the d point of the piezoelectric vibrator BC. The waveform is the second
As shown in Figures (a) and (+3), the photocoupler PCI is turned off in the case of weak operation with a small discharge amount, and the voltage waveform at the 0 point and the voltage waveform at the d point are It is as shown in FIG. 3(a), (+1).

” As mentioned in Section 2, in order to vibrate the piezoelectric vibrator BC,
Transistor Tr2. Tr3 is turned on and off to charge and discharge the piezoelectric vibrator BC, which has capacitor-like characteristics. , the time Td of the discharge waveform portion consisting of the falling portion and the lower limit portion are equal to each other.

By the way, in the above applied voltage control circuit, the piezoelectric vibrator BC
In order to apply voltages in both positive and negative directions, four transistors Tr (Tri to Tr4) and two coupling capacitors (C3, C4) are required, and since the current flowing through the control resistor R is alternating current, four diodes are required. (D3 to I)6) are required, which has the disadvantage of increasing costs.

<Purpose> Therefore, an object of the present invention is to provide a piezoelectric vibrating device in which an applied voltage control circuit can be manufactured at low cost, and the power consumption of a piezoelectric vibrator can be lower during weak operation than during strong operation.

<Example> Hereinafter, an example of the present invention will be described with reference to FIG. 4.5.6. Fig. 4 is an applied voltage control circuit diagram, and Figs. 5 and 6 are e of Fig. 4 during strong operation and weak operation of the piezoelectric vibrator BC, respectively.
The voltage waveforms at point and f are shown.

In FIG. 4, diodes D1. D2, resistance R1, R
2, R3, capacitors CI, C2, constant voltage diodes ZDI, Zr)2, and the first transistor Tri constitute a constant voltage circuit, and by controlling the base voltage of the transistor Trl, the power supply AC is varied. Also, a constant positive voltage flows between the collector and emitter of the transistor Tr1.

ICI is a first operational amplifier (hereinafter abbreviated as operational amplifier) for generating a positive square wave pulse as an output signal;
R5, R6, R7, R9 are bias resistors for operating the operational amplifier ICI, C3 is a capacitor for determining the pulse width of the square wave, R8, VR are the same resistors, D3. D4 is also a diode, and in the circuit made up of these, the voltage appearing across the capacitor C3 increases with time constant R8・C3 and decreases with time constant VR−C3, so the operational amplifier ICI The pulse width of the output voltage waveform is controlled by R8·C3, and the pulse separation is controlled by \7R-C3.

Next, IC2 is a second operational amplifier for generating a square wave integral wave as an output signal, R10 is its input resistance, and C4
is a capacitor for feedback impedance, R11 is a resistor, and R12 is a resistor for offset compensation of operational amplifier IC2. The circuit configured with these integrates the square wave pulse that is the output signal of the first operational amplifier ICI and outputs it. At point e on the side, a pulse with a positive voltage waveform as shown in Fig. S (,) and Fig. 6 (,) is obtained.

Next, R13 is an input coupling resistor for the second transistor Tr2, and C5 is also a capacitor.

When the input base current of transistor Tr2 is zero, transistor Tr2 is OFF, and the voltage between the collector and emitter of transistor Tr2 is RLI +, x Y Then, the L transistor Tr2 is turned on and the current is shunted.

Assuming that a constant voltage is now applied between the discharging resistors RA and RB, the same input voltage is applied to the oscillator BC of the transistor Tr2 ('')FF, and the input base current of the transistor Tr2 is Figure (a), Figure 6 (
, ) increases in accordance with the waveform voltage, the amplified current shunted to the transistor Tr2 increases, the voltage at point f on the collector side gradually decreases, and as the input base current of the transistor Tr2 decreases in accordance with the waveform voltage, the The amplified current shunted to Tr2 ceases, and the voltage at one point on the collector side gradually increases.

Therefore, the voltage waveform at point e is
), the voltage waveforms at one point are shown in Figure 5 (1)) and Figure 6 (
11) It looks like a trapezoidal pulse.

In the above, the rising time T2 and falling time T1 of the trapezoidal pulse, which is the voltage waveform applied to the vibrator BC, can be set by the capacitance value of the capacitor C4, and the frequency of the trapezoidal pulse can be changed by changing the variable resistor VR. can be changed to the desired value.

That is, as described above, since the square wave pulse separation of the output voltage waveform of the operational amplifier IC1 is controlled by VR·C3, the frequency changes with a change in the variable resistor VR. In the present invention, the time (charging time) Tc of the charging waveform part consisting of the rising part and the upper limit part of the voltage waveform of the trapezoidal pulse is changed, and the time (charging time) Tc of the charging waveform part consisting of the falling part and the lower limit part of the voltage waveform of the trapezoidal pulse is changed. By keeping the time (discharge time) Td (on time of transistor Tr2) constant, the fifth
Switching between the strong operation shown in the figure and the weak operation shown in FIG. 6 is performed as follows.

That is, in this applied voltage control circuit, the applied frequency is switched by turning on and off the photocoupler PC1, which is made up of a light emitting element P1 and a light receiving element P2, by turning on and off the light emitting element P1 according to instructions from a microcomputer. , only when the photocoupler PC1 is on, the control resistor R is inserted in parallel with the variable resistor VR, and their combined resistance becomes small, and the input signal of the operational amplifier ICI changes, so the voltage waveform at point f becomes the fifth As shown in FIG. 6(b), the frequency is higher than that in FIG. 6(1) when the photocoupler PCI is off. In other words, in the case of strong operation that requires a large discharge amount, the photocoupler PCI is turned on; The voltage waveforms are as shown in Figure 5 (a) and (b), and the photocoupler PCI is turned off in the case of weak operation with a small discharge amount, and the voltage waveform at point e and point 1 at this time are The voltage waveform of is as shown in FIGS. 6(a) and (lr).

By the way, in order to vibrate the piezoelectric vibrator BC, it is necessary to charge and discharge the piezoelectric vibrator Be by turning on and off the transistor Tr2, but since the piezoelectric vibrator BC has capacitor-like characteristics, its power consumption is is hardly consumed when a steady voltage is applied. However, the discharge resistance RA.

RB mainly consumes power when the transistor Tr2 is on, that is, when the piezoelectric vibrator BC is being discharged.

Therefore, the transistor Tr2 only needs to be turned on for a sufficient period of time to discharge the charge of the piezoelectric vibrator BC.
It is preferable that the off-time is as short as possible because it reduces power consumption.

Therefore, in this embodiment, in an applied voltage control circuit that switches the discharge amount of the pump by switching the frequency of the voltage waveform, the on time (discharge time) Td of the transistor Tr2 is
Since this method keeps constant and switches the off time (charging time) Tc of transistor Tr2 to a longer or shorter time, power consumption can be reduced during weak operation where the discharging time Td is shorter than the charging time Tc, as shown in Figure 6. . In addition, in Fig. 3, both times Tc
, Td are mutually equal.

Further, the rise time T2 and the falling time T1 of the trapezoidal pulse are each set to 0.8 m5ec or more in order to send a sufficient current to the vibrator BC.

In the present example, the piezoelectric ceramic thin plate is lead zirconate titanate porcelain, and its thickness is 0.6IIIll.
The diameter of the disk is 28m+o, the thin metal plate is stainless steel, the thickness is 0.4a+m, and the circle is 1/E.
x if i In a piezoelectric vibrating device, the applied voltage control circuit includes an applied voltage control circuit that generates a voltage waveform consisting of a charging waveform portion that causes the piezoelectric vibrator to release charge, and a discharge waveform portion that causes the piezoelectric vibrator to release charge. The waveform is a positive or negative pulse waveform, and the time of the charging waveform portion of the pulse waveform is variable, while the time of the discharging waveform portion is kept approximately constant, thereby changing the frequency of the voltage waveform. The strength of the vibration is changed by

Therefore, according to the present invention, since the applied voltage control circuit applies a positive or negative voltage to the piezoelectric vibrator, the applied voltage control circuit can be manufactured at low cost by reducing the number of transistors, coupling capacitors, and diodes. Furthermore, since the time of the discharge waveform portion is kept at a substantially constant short time, there is an excellent effect that the power consumption of the piezoelectric vibrator can be reduced during weak operation than during strong operation.

[Brief explanation of the drawing]

Figures 1 (a), (1)), and (c) are a front view, a sectional view, and a bottom view showing the structure of the liquid feeding pump in the prior art, respectively, and Figure 1 (d) is the electric voltage of the applied voltage control circuit. circuit diagram,
Figures 2 (a) and (b) are voltage waveform diagrams at points 0 and d when the piezoelectric vibrator is in strong operation when the photocoupler is on, respectively in Figure 1 (d), and Figures 3 (a) and ( b) is a voltage waveform diagram at point 0 and point d during weak operation of the piezoelectric vibrator when the photocoupler is off, FIG. 4 is an applied voltage control circuit diagram in Example 1 of the present invention, and FIG. 5(a) , (b) are points e and f when the piezoelectric vibrator is strongly operated when the photocoupler is on in Fig. 4.
FIGS. 6(a) and 6(b) are voltage waveform diagrams at points e and f when the piezoelectric vibrator is in weak operation. BC: piezoelectric vibrator, Tc: time of charging waveform portion of voltage waveform, Td: time of discharging waveform portion of voltage waveform, ICI, I
C2: Operational amplifier, R: Control resistor, R1-R13: Resistor, VR: Variable resistor, RA, RB: Discharge resistor, C1-C
5: Capacitor, D1-D4: Diode, Trl, T
r2:) transistor, F' CI: photocoupler. Applicant Sharp Co., Ltd. Agent Tsunehisa Nakamura No. sy1 Figure Procedure Amendment (Guy) July 20, 1982 1, Indication of the case Patent Application No. 50222/1983 2, Name of invention and device Piezoelectric vibrating device 3. Relationship with the case of the person making the amendment Applicant name Address 5, Imperial Senba, 4-57 Minamihonmachi, Higashi-ku, Osaka City Date of amendment order (Showa year, month, day) (shipment date) 6. Number of inventions increased by amendment 7 , page 15, lines 6-15 of the specification subject to amendment [Fig. 2...]. ” is corrected as follows. [Figure 2 is a voltage waveform diagram, and parts (a) and (b) of it show the voltage waveforms at points 0 and d when the photocoupler is on and the piezoelectric vibrator is strongly operated in Figure 1 (d), respectively. It shows
Figure 3 is a voltage waveform diagram, parts (a) and (b) of which show the voltage waveforms at point 0 and point d, respectively, when the piezoelectric vibrator is in weak operation when the photocoupler is off in Figure 1 (d). 4 is an applied voltage control circuit diagram in an embodiment of the present invention, and FIG. 5 is a voltage waveform diagram, the (a) and (+1) parts of which are the piezoelectric vibrators when the photocoupler is on in FIG. 4, respectively. Figure 6 shows the voltage waveforms at points e and f during strong operation, and parts (a) and (I) of it are the voltage waveforms at points e and f during weak operation of the piezoelectric vibrator, respectively. The voltage waveform of is shown. ”

Claims (1)

[Claims] a piezoelectric vibrator that directly converts electricity into mechanical vibration; and an applied voltage control circuit that generates a voltage waveform consisting of a charging waveform portion that applies voltage to the piezoelectric vibrator and a discharge waveform portion that causes the piezoelectric vibrator to release charge. In a piezoelectric vibrating device equipped with
The applied voltage control circuit is configured to make the voltage waveform applied to the piezoelectric vibrator a pulse waveform in a positive or negative direction, and to make the time of the charging waveform portion of the pulse waveform variable and to keep the time of the discharging waveform portion substantially constant. A piezoelectric vibrating device characterized by: