JPH10210774A - Pulse generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small pulse generator suitable for driving an electromechanical conversion element in which the number of components is decreased and power consumption is reduced. SOLUTION: An oscillation circuit 2 is driven from a low voltage power supply to generate a sine wave voltage Vs1 which is stepped up to a voltage Vsh through a step-up transformer 3. A switching circuit 6 is inserted between the secondary of the step-up transformer 3 and a piezoelectric element 8 and controlled to deliver an output voltage Vsh as a trapezoidal voltage Vpzt. Control timing is obtained from the sine wave voltage Vs1 or the output voltage Vsh from the step-up transformer and the switching circuit 6 is controlled with a timing pulse generated from a timing pulse generating section 9. A switching circuit 7 discharges the piezoelectric element 8 and the discharge period is controlled with a timing pulse from the timing pulse generating section 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pulse generator,
In particular, the present invention relates to a pulse generator suitable for driving a driving device using an electromechanical transducer.

[0002]

2. Description of the Related Art For driving a camera or other components constituting a precision instrument, a piezoelectric element is caused to undergo expansion and contraction displacement, the expansion and contraction displacement is transmitted to a driving member, and driven by a moving member frictionally coupled to the driving member. A linear actuator and a rotary actuator configured to move a member are known (JP-A-4-69070, JP-A-63-1107).
No. 4).

FIG. 15 shows an example of a driving apparatus applied to driving a zoom lens mounted on a camera, in which a support 22 for supporting a lens barrel 21 of a lens as a driven member is slidably fitted. The portions 22a and 22b are fitted to the drive shaft 23 by slidable frictional contact. The drive shaft 23 is supported by support portions 25 and 26 of a frame 27 so as to be freely displaceable in the axial direction. One end of the piezoelectric element 8 that is displaced in the thickness direction is fixed to an axial end of the drive shaft 23, and the other end of the piezoelectric element 8 is fixed to the frame 27, and the displacement of the piezoelectric element 8 in the thickness direction is performed. As a result, the drive shaft 23 is displaced in the axial direction.

Further, reference numeral 24 denotes a leaf spring, which is attached to the sliding fitting portions 22a and 22b of the support 22 by small screws (not shown) as shown in FIG.
5 is fixed from below. A bent portion 24a that is bent upward is formed at the central portion of the leaf spring 24,
This is because the bent portion 24a is pressed against the drive shaft 23 to generate an appropriate frictional force at the contact portion.

In the drive mechanism shown in FIG. 15, when a drive pulse having a waveform consisting of a gentle rising portion and a rapid falling portion as shown in FIG. In the rising portion, the piezoelectric element 8 gradually expands and displaces in the thickness direction, and the drive shaft 2
Reference numeral 3 moves gently in the direction of arrow a in the axial direction.

At this time, the frictional force between the drive shaft 73 and the sliding fitting portions 22a and 22b of the support 22, and the frictional force between the drive shaft 23 and the bent portion 24a of the leaf spring 24 are driven by the piezoelectric element 8. If the force is not more than the force applied to the shaft 23, the support 22
Moves in the direction of arrow a together with the drive shaft 23 while being frictionally coupled to the drive shaft 23, and the lens barrel 21 moves in the direction indicated by arrow a.

On the other hand, at the rapid falling portion of the drive pulse, the piezoelectric element 8 rapidly shrinks in the thickness direction, so that the drive shaft 23 moves rapidly in the axial direction in the direction opposite to the arrow a. At this time, the sliding fitting portions 22a, 22
b supports the frictional force between the drive shaft 23 and the sliding fitting portions 22a and 22b of the support 22 due to the inertial force, and the friction between the drive shaft 23 and the bent portion 24a of the leaf spring 24. Since the lens barrel 21 stays at that position by overcoming the frictional force, the lens barrel 21 does not move.

The drive pulse having the above-mentioned waveform (trapezoidal waveform) is continuously applied to the piezoelectric element 8 so that the lens barrel 21
Can be continuously moved in the direction indicated by the arrow a. In order to move the lens barrel 21 in the direction opposite to the arrow a, a drive pulse having a waveform composed of a rapid rising portion and a gentle falling portion as shown in FIG. It can be achieved by applying.

[0009]

However, the driving pulse generator for generating the driving pulse described above uses a complicated circuit as described below.

First, since a relatively high voltage (several tens of volts) is required as the peak voltage of the driving pulse applied to the piezoelectric element, when the power supply is a low-voltage power supply (several volts) such as a battery, etc. The need for a complicated booster circuit for generating a high voltage.

Secondly, if a combination of a constant current circuit, a switching circuit and a timing circuit for controlling the control timing is used as a circuit for generating a trapezoidal waveform driving pulse, the whole device becomes large and the power consumption becomes large. .

An object of the present invention is to provide a new drive pulse generator which solves the above-mentioned problems of the conventional drive pulse generator.

[0013]

The present invention solves the above-mentioned problems. According to the first aspect of the present invention, a sine wave generating means and a desired phase position of a sine wave generated by the sine wave generating means are determined. Timing pulse generating means for generating a timing pulse by designating, and switch means for turning on / off the output of the sine wave to the load based on the timing pulse designating a desired phase position outputted from the timing pulse generating means And characterized by the following.

When the load is a capacitive load, the pulse generating device includes second switch means for discharging the electric charge charged in the load, and the second switch means includes the timing pulse generating means. The desired phase position output from the means may be activated by a designated timing pulse.

The sine wave generating means may be provided with a DC power supply for outputting a predetermined voltage, and the generated sine wave may be offset from a reference potential by the voltage of the DC power supply.

According to a fourth aspect of the present invention, there is provided a pulse generator suitable for being applied to a driving mechanism for applying a pulse voltage to an electromechanical transducer to generate a telescopic displacement and driving a mechanism member by the generated displacement. Wave generating means, timing pulse generating means for generating a timing pulse by designating a desired phase position of the sine wave generated by the sine wave generating means, and turning on / off the output of the sine wave to the electromechanical transducer. A first switch for turning off; and a second switch for discharging a charge of the electromechanical transducer. The first switch and the second switch output from the timing pulse generator. It is controlled to operate based on a timing pulse designating the desired phase position.

The switch means is a switch means composed of a semiconductor device. The sine wave generating means includes a high voltage generating circuit including a semiconductor element and a transformer.

Further, the first switch means for turning on / off the output of the sine wave to the electromechanical transducer, and the second switch means for discharging the charge of the electromechanical transducer, comprise the timing pulse generator. Means for converting the polarity of the pulse voltage applied to the electromechanical transducer based on the timing pulse specifying the desired phase position output from the means and applying the converted pulse voltage.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. The oscillating circuit 2 to which the low-voltage power supply 1 is connected generates a voltage Vs1 having a sine wave waveform,
To increase the sine wave waveform voltage to a required voltage level Vsh as a drive pulse. A switching circuit 6 is provided between a boost output side (secondary side) of the boost transformer 3 and the piezoelectric element 8;
A timing pulse generator 9 outputs a timing pulse to the switching circuit 6 so that the output voltage Vsh (sine wave voltage) of the step-up transformer 3 is processed into a trapezoidal waveform voltage Vpzt by the switching circuit 6 and output to the piezoelectric element 8. And control. The signal that defines the timing in the timing pulse generator 9 is the sine wave waveform voltage Vs1 described above.
Can be obtained from the operating state of the oscillation circuit 2 that generates the voltage, or from the sinusoidal waveform voltage Vs1 or the output voltage Vsh of the step-up transformer.

The switching circuit 7 is a switching circuit for discharging the electric charge charged in the piezoelectric element 8, and is also controlled by a timing pulse output from the timing pulse generator 9.

As a result, a high voltage required as a driving pulse can be easily obtained, and a constant current circuit is not required.
Only a switching circuit and a timing pulse generation circuit for controlling the switching circuit are required. Since an oscillation circuit for generating a sine wave waveform can be easily configured, the circuit configuration is simplified and power consumption is reduced.

[0022]

Embodiments of the present invention will be described below.
FIG. 1 is a diagram for explaining the operation timing of the drive pulse generation circuit of the first embodiment to which the present invention is applied, and FIG. 2 is a diagram for explaining the operation timing of the drive pulse generation circuit shown in FIG.

In FIG. 1, reference numeral 2 denotes an oscillation circuit for generating a sine wave waveform, and power is supplied from a low-voltage power supply 1 such as a battery. Reference numeral 3 denotes a step-up transformer, which is an output voltage V of the oscillation circuit 2.
When s1 is input to the primary side of the step-up transformer 3, the sine wave voltage Vsh boosted to the voltage level required as a drive pulse as shown in FIG. Is output. Switching circuits 6 and 7 are ON / OFF controlled by timing pulses output from a timing pulse generator 9. Reference numeral 8 denotes a piezoelectric element.

The input side of the timing pulse generator 9 is connected to the secondary side of the step-up transformer 3, and the control timing of the timing pulse is controlled by the input sine wave voltage Vsh (FIG. 2).
(A), zero-cross points (A, C, E, etc.) are defined, and timing pulses 9a, 10a as shown in (b) and (c) of FIG. 2 are generated. Further, from the timing pulse generator 9, the above-described timing pulse 9a,
Based on 10a, timing pulses 9b and 10b for controlling the switching circuits 6 and 7 as shown in FIGS. 2D and 2E are output. Timing pulse 9b,
The control at the time point B of 10b is obtained based on the timing delayed from the time point A of the zero cross by a time of a quarter cycle of the sine wave voltage Vsh.

The timing pulse 10c shown in FIG. 2 (f) is for the second embodiment described later and will not be described here.

Next, the operation of the drive pulse generation circuit will be described with reference to FIG. When the sine wave voltage Vsh output from the secondary side of the step-up transformer 3 changes from negative to positive at the time point A (time point A of zero cross), the timing pulse generator 9 outputs “H” of the timing pulse 9b and “H” of the timing pulse 10b. Since "L" is output, the switching circuit 6 is turned on, and the switching circuit 7 is turned off. As a result, the output voltage Vsh on the secondary side of the step-up transformer 3 is applied to the piezoelectric element 8, and as shown in FIG. 2 (g), the applied voltage Vpzt of the piezoelectric element 8 has the same waveform as the voltage Vsh. , And is charged to reach the peak voltage Vsh.

When the time point B is reached, the timing pulse generator 9 outputs "L" of the timing pulse 9b, and the switching circuit 6 is turned off. At the same time, the timing pulse generator 9 outputs "H" of the timing pulse 10b. , The switching circuit 7 is turned on. As a result,
The charging of the piezoelectric element 8 is stopped, and the charge is rapidly discharged through the switching circuit 7. The discharge resistance is
It is the sum of the internal impedance of the piezoelectric element 8 and the ON resistance of the switching circuit 7. The applied voltage Vpz of the piezoelectric element 8
t falls from the peak voltage Vsh to zero (see FIG. 2 (g)).

When time C (zero-crossing time C) is reached, the voltage Vsh changes from positive to negative. At this time, the timing pulse output from the timing pulse generator 9 does not change. The applied voltage Vpzt is maintained at zero (see (g) of FIG. 2).

At time D, the timing pulse output from the timing pulse generator 9 does not change, so that the voltage Vpzt applied to the piezoelectric element 8 is maintained at zero (see FIG. 2 (g)). Further, when the time point E is reached, the state becomes the same as the time point A, and the same operation as the time point A is started.

As described above, the drive pulse generating circuit of the first embodiment can generate a substantially trapezoidal drive pulse Vpzt as shown in FIG.

Next, a second embodiment will be described. Second
In this embodiment, the timing of outputting "H" of the timing pulse 10b output from the timing pulse generator 9 of the first embodiment is delayed by the time Tc, and as shown in FIG. The timing pulse 10c outputs "H" at a point in time after the delay. When the switching circuit 7 is controlled by the timing pulse 10c, the timing pulse 10
Since c is kept OFF and turned ON at the time when it is delayed by the time Tc, the applied voltage Vpzt of the piezoelectric element 8 is maintained from the time B until a time when it is delayed by the time Tc.
Is rapidly discharged through the switching circuit 7.

As a result, the drive pulse generation circuit of the second embodiment has a wider width than the substantially trapezoidal drive pulse Vpzt shown in FIG. A substantially trapezoidal drive pulse Vpzt as shown in (h) can be generated. The width of the trapezoidal pulse can be achieved by adjusting the delay time Tc for outputting the timing pulse 10c.

Next, a third embodiment will be described. Third
In the embodiment, as shown in the circuit of FIG.
A DC power supply 11 for outputting a voltage Vos is inserted on the next side, and the output voltage Vsh is offset from the earth potential by the voltage Vos. Since other circuit elements are the same as those of the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

FIG. 4 is a diagram for explaining the operation timing of the drive pulse generation circuit according to the third embodiment. Hereinafter, the operation of the third embodiment will be described with reference to FIG. Step-up transformer 3-2
The sine wave voltage Vsh output from the secondary side is offset by the voltage Vos with respect to the earth potential as shown in FIG.

When the output voltage Vsh on the secondary side of the step-up transformer 3 changes from negative to positive at time A (zero-crossing time A), as shown in FIGS. 4B and 4C, the timing pulse generator 9 to “H” of the timing pulse 12
And “L” of the timing pulse 13 is output. As a result, the switching circuit 6 is turned on, and the switching circuit 7 is turned off. As a result, the output voltage Vsh on the secondary side of the step-up transformer 3 is applied to the piezoelectric element 8, and FIG.
As shown in (a), the applied voltage Vpzt of the piezoelectric element 8 rises and charges with a waveform similar to the waveform of the voltage Vsh, and the peak voltage reaches Vsh.

When reaching the time point B, as shown in FIGS. 4B and 4C, the timing pulse generator 9 outputs "L" of the timing pulse 12 and the timing pulse 1
3 "H" is output. As a result, the switching circuit 6 is turned off and the switching circuit 7 is turned on. As a result, the charging of the piezoelectric element 8 is stopped, and
The charge is rapidly discharged through the switching circuit 7. The discharge resistance is the sum of the internal impedance of the piezoelectric element 8 and the ON resistance of the switching circuit 7. Piezoelectric element 8
Applied voltage Vpzt decreases from the peak voltage Vsh to zero (see FIG. 4A).

When time C (time C of zero crossing) is reached, the voltage Vsh changes from positive to negative. At this time, the timing pulse output from the timing pulse generator 9 does not change. The applied voltage Vpzt is maintained at zero (see FIG. 4A).

At time D, the timing pulse output from the timing pulse generator 9 does not change, so that the voltage Vpzt applied to the piezoelectric element 8 is maintained at zero (see FIG. 4A). Further, when the time point E is reached, the state becomes the same as the time point A, and the same operation as the time point A is started.

As described above, the drive pulse generating circuit of the third embodiment can generate a substantially trapezoidal drive pulse Vpzt as shown in FIG.

In the third embodiment, as described in the second embodiment, the output timing of the timing pulse 12 output from the timing pulse generator 9 is delayed by the time Tc, and the timing pulse 13c is output. In this case, the timing pulse 13c can be obtained even at the time point B.
Is maintained at "L", and becomes "H" at a time delayed from the time B by the time Tc. Therefore, the applied voltage Vpzt of the piezoelectric element 8 is maintained until a time delayed from the time B by the time Tc, and thereafter, the piezoelectric element 8 Is rapidly discharged through the switching circuit 7.

As a result, a substantially trapezoidal drive pulse Vpzt having a waveform shown by a dotted line in FIG. 4A can be generated. The width of the trapezoid can be achieved by adjusting the delay time Tc for outputting the timing pulse 13c.

FIG. 5 is a timing chart showing the timing pulses 12, 13 (or 13c) in the driving pulse generating circuit shown in FIG.
5B, the timing pulse 12 is set to “H” at time B, the timing pulse 13 is set to “L”, and the timing pulse 12 is changed to “L” at time C, as shown in FIGS. 5B and 5C. L shows the case where the timing pulse 13 is set to "H". Thereby, (a) of FIG.
As shown in the figure, the trapezoidal shape of the drive pulse Vpzt can be reversed left and right, and rapid charging and gentle discharging can be performed on the piezoelectric element 8, so that the driving mechanism is driven in the direction opposite to that described above. Can be driven.

FIG. 6 is a circuit diagram of the oscillation pulse generator 2, switching circuit 6, switching circuit 7, and timing pulse generator 9 in the drive pulse generator of the third embodiment shown in FIG. 3 is an example of a circuit specifically showing a configuration.

An oscillation circuit 2 for generating a sine wave waveform is composed of transistors Tr1 and Tr2, resistors R1 to R4, capacitors C2 to C5, and a transformer 3, and operates in a class C operation. It is. The transformer 3 is an oscillating coil with a center tap and is provided with a secondary winding and also serves as a step-up transformer. Reference numeral 1 denotes a power supply of the oscillation circuit 2, which is a low-voltage power supply. A DC power supply 11 for outputting a voltage Vos is inserted on the secondary winding side of the transformer 3, and the output voltage Vsh is offset from the ground potential by the voltage Vos. The output voltage of the transformer 3 becomes the voltage Vshos in which the voltage Vos is superimposed on the voltage Vsh.

The switching circuit 6 includes a diode D1, transistors Tr3 and Tr4, and inverter logic IN.
V, and resistors R5 to R7, and the switching circuit 7 includes a transistor Tr5 and resistors R8 to R10. The resistor R8 is a resistor for setting a discharge characteristic when discharging the electric charge of the piezoelectric element 8.

The diode D1 is composed of transistors Tr3 and T3.
The protection diodes r4 and Tr5 are used to prevent performance degradation and destruction due to the application of a reverse voltage to the emitter of each transistor when the output voltage Vshos of the transformer 3 is negative.

The timing pulse generator 9 has a comparator
And a microprocessor MPU. The output voltage Vshos of the transformer 3 is the comparator COM.
The waveform is input to a waveform shaping circuit composed of P and becomes a rectangular wave for detecting a zero cross point of the voltage Vshos, and is input to the microprocessor MPU. The microprocessor MPU outputs timing pulses 12, 13 (or 13c) according to a built-in program. The switching circuits 6 and 7 receive the timing pulses 12 and 13 (or 13c) to perform a predetermined switching operation and generate a drive pulse Vpzt as shown in FIG.

As shown in the explanatory diagram of the operation timing of the drive pulse generating circuit shown in FIG. 4, when the timing pulse 12 and the timing pulse 13 are set to have opposite phases to each other, the switching circuit 6 shown in FIG. The function of the transistor Tr4 is changed by the transistor T of the switching circuit 7.
r5, it is possible to drive only with the timing pulse 13.

FIG. 7 shows an alternative circuit to the switching circuits 6 and 7 shown in FIG. 6, and as shown in FIG.
Remove the transistor Tr4 and set the collector of Tr5 to T
r3, and the timing pulse 13 is connected to Tr5.
Output to Accordingly, the discharging of the piezoelectric element 8 and the operation from ON to OFF of the transistor Tr3 can be performed simultaneously.

Thus, the configuration for generating the timing pulse 12, the transistor Tr4, the inverter INV, and the resistors R6 and R7 can be omitted.

FIG. 8 shows a driving pulse generating circuit according to the third embodiment shown in FIG. 6, in which the DC power supply of the voltage Vos inserted on the secondary winding side of the transformer 3 is omitted, and the primary winding of the transformer 3 is omitted. FIG. 9 shows a first DC power supply alternative circuit obtained from the power supply Vp1 on the side. A capacitor C11 is inserted between the terminal on the primary winding side and the ground, and the terminal of the secondary winding is connected here. As a result, the output voltage Vsh on the secondary winding side of the transformer 3 can be offset by the voltage Vos = Vp1 with respect to the earth potential, and the DC power supply 1 shown in FIG.
1 can be omitted.

FIG. 9 shows a driving pulse generating circuit according to the third embodiment shown in FIG. 6, in which the DC power supply of the voltage Vos inserted on the secondary winding side of the transformer 3 is omitted, and the secondary winding of the transformer 3 is omitted. A second DC power supply in which the negative period of the sine wave AC voltage Vsh induced on the side is rectified by the diode D3 to charge the capacitor C12, and the voltage generated at the terminal of the capacitor C12 is replaced by a DC power supply of the voltage Vos. 9 shows an alternative circuit. As a result, the output voltage Vsh on the secondary winding side of the transformer 3
Can be offset with respect to the earth potential, and the DC power supply 11 shown in FIG. 6 can be omitted.

FIGS. 10 and 11 show other means for generating a timing pulse. FIG. 10 shows the third means shown in FIG.
7 shows a circuit in which the switching circuits 6 and 7 of the drive pulse generation circuit of the embodiment are replaced with the circuit shown in FIG. 7 and further, alternative means for generating timing pulses are added.
FIG. 11 is a diagram for explaining the operation timing. Hereinafter, description will be made with reference to FIGS. 10 and 11.

In the oscillation circuit 2 for generating a sine wave waveform shown in FIG. 10, the transistors Tr1 and Tr2 are configured to operate in a class C operation. Therefore, Tr1, Tr2
In the case where the polarities are shown, the emitter currents Ie1 and Ie2 are
The current flows intermittently with respect to the voltage Vsh at the timings shown in FIGS. 11B and 11D, and the pulsed voltages Ve1 and Ve1 are applied to both ends of the respective emitter resistors R3 and R4.
Ve2 is generated.

Therefore, these pulsed voltages Ve1, Ve
The waveform of e2 is shaped by the control timing generator 9, and the pulse voltages V1 and V2 as shown in FIGS.
Then, based on this, a timing pulse 14 as shown in FIG. 11 (f) is generated. As a result, the configuration of the control timing generator 9 can be configured with a simple waveform shaping circuit without depending on the microprocessor MPU.

FIG. 12 shows a modification of the timing pulse generating means shown in FIG.
1, intermittent base current Ib1 flowing to the base of Tr2,
A timing pulse is obtained using Ib2. Photocouplers PC1 and PC2 are inserted into the base circuits of the respective transistors Tr1 and Tr2, and the detected intermittent base currents Ib1 and Ib2 are waveform-shaped by the signal processing circuits SG1 and SG2, and the control timing generator 9 , From which a timing pulse 14 is generated. Thus, the configuration of the control timing generator 9 can be simplified.

FIGS. 13 and 14 show that the switching of the expansion / contraction direction of the piezoelectric element is achieved by switching the polarity of the piezoelectric element, so that the driving in the positive direction and the negative direction can be performed using the driving pulse having the same waveform. FIG. 13 shows a polarity switching drive circuit of a piezoelectric element, and FIG.
FIG. 4 is a diagram for explaining the operation timing.

Hereinafter, the polarity switching drive circuit and its operation will be described with reference to FIGS. As shown in FIGS. 14B and 14C, the timing pulse 15 is applied to the transistor Tr5, and the timing pulse 16 is applied to the transistor T5.
Give to r7. For example, when the timing pulse 16 is set to “H”
When the Tr 7 is kept in the ON state, the terminal 8 of the piezoelectric element 8
b is grounded via diodes Dc and Dd. In this state, when the timing pulse 15 is set to "L", the piezoelectric element 8
A drive pulse Vpzt as shown in FIG. 14A is applied to the terminal 8a, and expansion and contraction (slow expansion and rapid contraction) in the positive direction occurs in the piezoelectric element.

Next, the state of the timing pulse is inverted,
When the timing pulse 15 is set to "H" to keep the Tr5 in the ON state, the terminals 8a of the piezoelectric element 8 are connected to the diodes Da, Db.
Grounded. In this state, timing pulse 1
When 6 is set to "L", the drive pulse Vpzt is applied to the terminal 8b of the piezoelectric element 8, and the piezoelectric element undergoes expansion and contraction in the negative direction (rapid expansion and gentle contraction).

The embodiments of the present invention have been described above, and the modified examples and the alternative circuits of the circuit constituting the pulse generating circuit have been described. These modified examples and the alternative circuits are appropriately combined according to the purpose. It goes without saying that you can do it.

[0061]

As described above, according to the pulse generator of the present invention, a high voltage sufficient to drive the electromechanical transducer can be obtained even with a low-voltage power supply such as a battery, and a complicated There is no need for a booster circuit having a configuration. Also, a circuit for generating a drive pulse having a trapezoidal waveform suitable for driving the electromechanical transducer can be constituted only by a simple sine wave generation circuit, a transformer, a switching circuit, and a timing circuit for controlling the control timing thereof, It is possible to provide a pulse generator which is smaller than the conventional pulse generator, has a smaller number of parts, and consumes less power.

[Brief description of the drawings]

FIG. 1 shows a drive pulse generation circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating operation timings of the drive pulse generation circuit shown in FIG.

FIG. 3 shows a drive pulse generation circuit according to a third embodiment.

FIG. 4 is a diagram illustrating operation timing of the drive pulse generation circuit shown in FIG.

FIG. 5 is a view for explaining a drive pulse waveform when the timing pulse generation timing of the drive pulse generation circuit shown in FIG. 3 is changed.

FIG. 6 is a circuit diagram specifically showing a configuration of a drive pulse generation circuit shown in FIG. 3;

7 is an alternative circuit diagram of the switching circuit in the drive pulse generation circuit shown in FIG.

FIG. 8 is a first alternative circuit diagram of a DC power supply in the drive pulse generation circuit shown in FIG. 6;

9 is a second alternative circuit diagram of the DC power supply in the drive pulse generation circuit shown in FIG.

FIG. 10 is a circuit diagram showing another example of the timing pulse circuit.

FIG. 11 is a diagram illustrating operation timing by the timing pulse circuit shown in FIG.

FIG. 12 is a circuit diagram showing another example of the timing pulse circuit.

FIG. 13 is a diagram of a polarity switching drive circuit for switching and driving the polarity of a piezoelectric element.

14 is a diagram illustrating operation timing of the polarity switching drive circuit illustrated in FIG.

FIG. 15 is a perspective view illustrating a configuration of a driving device using a piezoelectric element.

FIG. 16 is a diagram illustrating a waveform of a drive pulse applied to a piezoelectric element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply 2 Oscillation circuit which generates a sine wave waveform 3 Step-up transformer 6, 7 Switching circuit 8 Piezoelectric element 9 Timing pulse generator

Claims (7)

[Claims] 1. A sine wave generating means, a timing pulse generating means for designating a desired phase position of a sine wave generated by the sine wave generating means and generating a timing pulse, and an output from the timing pulse generating means A switch means for turning on / off the output of the sine wave to the load based on the timing pulse for designating the desired phase position. 2. When the load is a capacitive load, the switch includes a second switch for discharging a charge charged in the load, and the second switch preferably outputs a signal output from the timing pulse generator. 2. The pulse generator according to claim 1, wherein the pulse generator is operated by a timing pulse specifying the phase position of the pulse. 3. The sine wave generating means is provided with a DC power supply for outputting a predetermined voltage, and the generated sine wave is offset from a reference potential by a voltage of the DC power supply. Pulse generator. 4. A pulse generator suitable for being applied to a driving mechanism for applying a pulse voltage to an electromechanical transducer to generate a telescopic displacement and driving a mechanism member by the generated displacement, comprising: a sine wave generating means; Timing pulse generating means for generating a timing pulse by designating a desired phase position of the sine wave generated by the sine wave generating means; and a first for turning on / off an output of the sine wave to the electromechanical transducer. Switch means; and second switch means for discharging the charge of the electromechanical transducer, wherein the first switch means and the second switch means have a desired phase position output from the timing pulse generating means. Characterized in that the pulse generator is controlled to operate based on a timing pulse designating the following. 5. A pulse generator according to claim 1, wherein said switch means is a switch means comprising a semiconductor element. 6. The pulse generator according to claim 1, wherein said sine wave generator includes a high-voltage generation circuit including a semiconductor element and a transformer. 7. A first switch means for turning on / off the output of the sine wave to the electromechanical transducer, and a second switch means for discharging a charge of the electromechanical transducer,
5. The apparatus according to claim 4, further comprising means for converting the polarity of a pulse voltage applied to the electromechanical transducer based on a timing pulse designating a desired phase position output from the timing pulse generating means and applying the pulse voltage. A pulse generator as described.