JP2001025709A - Method for driving piezoelectric vibrator and drive circuit therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to efficiently obtain large amplitude over a long time by impressing electric fields of an always the same direction as a polarization direction to respective piezoelectric substances of which the polarization directions face the same direction. SOLUTION: The piezoelectric vibrator 1 is formed by sticking the piezoelectric substance 11 consisting of piezoelectric ceramics onto a diaphragm 10 and sticking the piezoelectric substance 12 to the rear surface of the diaphragm 10. Quadrisected weights 14 are fixed to the circumference of the diaphragm 10 by holding the piezoelectric substance 11 with a holding member 13. The piezoelectric substances 11 and 12 are reverse biased by DC power sources 4 and 5 and the excitation voltages of the same phase are set by an AC power source 3 within the range of the bias voltage. The electric fields of always the forward direction are impressed to the respective piezoelectric substances 11 and 12. The same bias voltages varying in the absolute value are, therefore, impressed to the two piezoelectric substances 11 and 12 when the excitation respective voltages are respectively at a mid-point potential and, therefore, the two piezoelectric substances 11 and 12 spread by the same quantity and a vibrator does not deflect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a circuit for driving a piezoelectric vibrator, and more particularly to a vibrator (vibration alarm) for a portable telephone terminal, an alarm, a speaker or a wristwatch vibrator (vibration alarm).
The present invention relates to a driving method and a driving device for a piezoelectric vibrator used for an alarm, an alarm, and the like.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a driving method of a conventional piezoelectric vibrator. The piezoelectric vibrator 1 has two piezoelectric bodies 11 and 12 bonded to each other via a vibration plate 10.
The piezoelectric bodies 11 and 12 are polarized in the same direction, and an AC voltage is applied from the AC power supply 2 to the electrodes on both surfaces having the same potential. For this reason, the two piezoelectric bodies 11 and 12 expand and contract in the opposite directions, and obtain vibration as a vibrator.

[0003]

In the driving method shown in FIG. 7, one of the two piezoelectric members 11 and 12 (the lower piezoelectric member 12 in FIG. 7) has a reverse electric field opposite to the polarization direction. Become. For this reason, if the level or application time is excessive,
There is a problem that the degree of polarization is deteriorated.

[0004] Therefore, a main object of the present invention is to provide a driving method and a driving circuit of a piezoelectric vibrator which are efficient and can obtain a large amplitude for a long time.

[0005]

The invention according to claim 1 is
A method for driving a piezoelectric vibrator having a structure in which a plurality of piezoelectric bodies are bonded to a metal plate, wherein the polarization directions of the plurality of piezoelectric bodies are in the same direction, and each of the piezoelectric bodies is always in the same direction as the polarization direction. Is applied.

According to a second aspect of the present invention, there is provided a driving circuit for a piezoelectric vibrator having a structure in which a plurality of piezoelectric bodies are bonded to a metal plate, wherein the boosting circuit boosts a DC voltage to a DC voltage several times higher. An oscillation circuit that oscillates based on the output voltage of the booster circuit and outputs an AC voltage; and amplifies the AC voltage output from the oscillator circuit so that the AC voltage swings between the boosted DC potential and half the potential. A non-inverting amplifier circuit applied to one piezoelectric body of the piezoelectric vibrator, and an inverting amplifier that inverts and amplifies an AC voltage output from the oscillation circuit so as to oscillate between a half of the boosted potential and a ground potential; And an inverting amplifying circuit that inverts the output of the amplifying circuit so as to have the same phase as the output of the amplifying circuit and applies the inverted signal to the other piezoelectric body of the piezoelectric vibrator.

According to a third aspect of the present invention, there is provided a driving circuit for a piezoelectric vibrator having a structure in which a plurality of piezoelectric bodies are bonded to a metal plate, wherein the boosting circuit boosts a DC voltage to a DC voltage several times higher. An inverting chopper circuit that outputs a negative DC voltage of the DC voltage output from the booster circuit, an oscillation circuit that oscillates based on the output voltage of the booster circuit and outputs an AC voltage, and amplifies the AC voltage output from the oscillator circuit as it is A non-inverting amplifier circuit to apply to one piezoelectric body of the piezoelectric vibrator and inverts and amplifies the polarity of the AC voltage of the oscillation circuit output based on the negative DC voltage output from the inverting chopper circuit, and further non-inverting amplification And an inverting amplifier circuit that applies a signal inverted to be in phase with the output of the circuit to the other piezoelectric body of the piezoelectric vibrator.

[0008]

FIG. 1 is a perspective view of a piezoelectric vibrator according to an embodiment of the present invention, and FIG. 2 is a view for explaining a method of driving the piezoelectric vibrator shown in FIG.
FIG. 3 is a diagram for explaining the concept of vibration.

The piezoelectric vibrator 1 has a piezoelectric body 11 made of piezoelectric ceramic adhered to a vibration plate 10, and a piezoelectric body 12 (not shown) is adhered to the lower surface of the vibration plate 10. The piezoelectric body 11 is held on the vibration plate 10 by a holding member 13, and a weight 14 divided into four parts is fixed around the vibration plate 10.

The piezoelectric vibrator 1 shown in FIG. 1 is driven based on the principle shown in FIG. That is, the piezoelectric body 1
DC power supplies 4 and 5 bias the DC power supplies 1 and 12 in opposite directions, and the AC power supply 3 sets an in-phase excitation voltage within the range of the bias voltage. Thereby, each piezoelectric body 1
A forward electric field is always applied to 1 and 12. Therefore, when each excitation voltage is at the midpoint potential, the same bias voltage having a different absolute value is applied to the two piezoelectric members 11 and 12, and as shown in FIG. 11 and 12 expand by the same amount, and the vibrator does not bend.

Next, the AC signal is, for example, 9
When the phase is changed by 0 deg, the largest electric field is applied to one of the piezoelectric bodies, so that the spread is maximum, while the other is close to GND or the GND potential, so that it is shown in FIG. As described above, the piezoelectric body shrinks compared to the case of the above-described midpoint potential, and the vibrator is biased to one side. Further, if the phase changes by 180 deg, FIG.
As shown in (c), it will bend in the opposite direction.

Therefore, according to one embodiment of the present invention, an electric field is applied to the two piezoelectric members only in the forward direction, and the two piezoelectric members 11 and 12 expand and contract, respectively, so that a large amplitude can be efficiently obtained. Can be. In addition, the characteristics do not deteriorate even when used for a long time.

FIG. 4 is a block diagram showing a driving circuit of the piezoelectric vibrator according to one embodiment of the present invention. FIG.
, The power supply voltage Vcc shown in FIG.
, The booster circuit 21 boosts the power supply voltage Vcc, and as shown in FIG.
b is generated and supplied to the oscillation circuit 22. The oscillating circuit 22 generates a rectangular wave between the DC voltages Vb and Vb / 2 as shown in (c) and passes through a low-pass filter (LPF) to perform waveform shaping as shown in (d).

The output (e) of the low-pass filter 23 is applied to an electrode of one piezoelectric body 11 of the piezoelectric vibrator 1 by a non-inverting amplifier circuit 24. The output of the low-pass filter 23 is provided to a first inverting amplifier 25. The first inverting amplifier 25 uses the potential of Vb / 2 as a reference potential, converts between Vb / 2 and GND to a signal having a phase opposite to that of (d) as shown in FIG. The signal is supplied to the amplifier circuit 26. The second inverting amplifier circuit 26 converts the Vb / 4 potential into a signal having the same phase as (e) as shown in (g) as a reference potential and supplies the signal to the other piezoelectric body 12 of the piezoelectric vibrator 1.

As described above, in the embodiment shown in FIG. 4, between the piezoelectric bodies 11 and 12 of the piezoelectric vibrator 1, 3Vb / 4 is used as the reference potential as shown in FIGS. By applying a signal and a signal having the same potential with Vb / 4 as a reference potential, an electric field is applied only to the two piezoelectric bodies 11 and 12 in the forward direction. Even when used for a long time, its characteristics do not deteriorate.

FIG. 5 is a block diagram of a driving circuit according to another embodiment of the present invention. In the embodiment shown in FIG. 5, a DC voltage of -Vb is generated by the inverting chopper circuit 27 as shown in FIG.
Give 5 The first inverting amplifier circuit 25 uses the DC voltages Vb and −Vb as a DC power source, and sets the output signal of the low-pass filter 23 to GND as shown in FIG.
Between -Vb and -Vb into a signal having a phase opposite to that of (d).
To the inverting amplifier circuit 26. Second inverting amplifier circuit 26
The signal of (g) is converted into a signal similar to the output signal (e) of the non-inverting amplifier 24 as shown in (h) and given to the electrode of the piezoelectric body 12 as shown in (h).

In the embodiment shown in FIG.
1 and 12, a signal e that oscillates between GND and Vb;
By giving an in-phase signal h having an amplitude between −Vb and GND, an electric field is applied only to the two piezoelectric bodies 11 and 12 in the forward direction, so that a large amplitude can be obtained efficiently. In addition, the characteristics do not deteriorate even when used for a long time.

FIG. 6 shows the relationship between the time and the rate of change of the amount of vibration of the driving circuit according to the conventional example and one embodiment of the present invention, and the solid line is according to the embodiment of the present invention shown in FIGS. And the dotted line shows a conventional example. As is clear from FIG. 6, in the embodiment according to the present invention, the rate of change of the amount of vibration over time can be reduced, and a large amplitude can be obtained efficiently over a long period of time, as compared with the conventional example. be able to.

It should be noted that the embodiments disclosed this time are illustrative in all aspects and are not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0020]

As described above, according to the present invention, a large amplitude can be efficiently obtained for a long time by applying AC voltages having different biases to two piezoelectric bodies.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a piezoelectric vibrator used in an embodiment of the present invention.

FIG. 2 is a diagram for explaining a method of driving a piezoelectric vibrator according to one embodiment of the present invention.

FIG. 3 is a diagram illustrating a concept of vibration in a driving method of the piezoelectric vibrator according to FIG. 2;

FIG. 4 is a block diagram of a drive circuit according to an embodiment of the present invention.

FIG. 5 is a block diagram of a drive circuit according to another embodiment of the present invention.

FIG. 6 is a diagram showing a comparison between a time and a vibration amount change rate according to a conventional example and an embodiment of the present invention.

FIG. 7 is a diagram illustrating a driving method of a conventional piezoelectric vibrator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 piezoelectric vibrator 10 diaphragm 11, 12 piezoelectric body 21 booster circuit 22 oscillator circuit 23 low-pass filter 24 non-inverting amplifier circuit 25 first inverting amplifier circuit 26 second inverting amplifier circuit 27 inverting chopper

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) G10K 9/12 102B F-term (Reference) 5D004 AA01 CC04 CC06 DD01 FF09 FF10 5D107 AA02 AA03 AA09 BB08 CC01 CD03 5J079 AA03 BA03 BA32 BA41 FB00 FB03 FB25 GA09 5K023 AA07 HH04 HH05

Claims (3)

[Claims] 1. A method for driving a piezoelectric vibrator having a structure in which a plurality of piezoelectric bodies are bonded to a metal plate, wherein the polarization directions of the plurality of piezoelectric bodies are in the same direction. A method for driving a piezoelectric vibrator, wherein an electric field in the same direction as the polarization direction is always applied. 2. A driving circuit for a piezoelectric vibrator having a structure in which a plurality of piezoelectric bodies are bonded to a metal plate, comprising: a boosting circuit for boosting a DC voltage to a DC voltage several times higher; and an output voltage of the boosting circuit. An oscillating circuit that oscillates on the basis of and outputs an AC voltage; and the piezoelectric vibrator amplifies the AC voltage output from the oscillating circuit as it is so as to oscillate between the boosted DC potential and half the potential. A non-inverting amplifying circuit to be applied to one of the piezoelectric bodies;
And an inverting amplifier circuit for inverting and amplifying the voltage between the potential of V./2 and the ground potential, further inverting the signal so as to have the same phase as the output of the non-inverting amplifier circuit, and applying the inverted signal to the other piezoelectric body of the piezoelectric vibrator. A driving circuit for a piezoelectric vibrator, comprising: 3. A driving circuit for a piezoelectric vibrator having a structure in which a plurality of piezoelectric bodies are bonded to a metal plate, comprising: a boosting circuit for boosting a DC voltage to a DC voltage several times higher; An inverting chopper circuit that inverts the polarity of the DC voltage and outputs a negative DC voltage, an oscillation circuit that oscillates based on the output voltage of the booster circuit and outputs an AC voltage, and an AC voltage output from the oscillation circuit. A non-inverting amplifying circuit that amplifies as it is and provides it to one piezoelectric body of the piezoelectric vibrator; and inverts and amplifies the polarity of the AC voltage of the oscillation circuit output based on a negative DC voltage output from the inverting chopper circuit. Further comprising an inverting amplifier circuit for applying a signal inverted to be in phase with the output of the non-inverting amplifier circuit to the other piezoelectric body of the piezoelectric vibrator. Operated device.