JPH1189252A - Driving pulse generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving pulse generator suitable for a driving equipment using an electromehcanical transducer (piezoelectric element) which can control a driving speed without deleting driving pluses. SOLUTION: A sine wave driving pulse generator 12 synchronizes with a timing signal A outputted from a CPU 11, generates specified sine wave driving pluses, and outputs them to a switching part 14. When the CPU 11 receives a speed command signal C from an external equipment, the CPU outputs a timing signal B for cut-off command to the switching part 14, at the timing corresponding to an ordered speed. Thereby the driving pulses outputted from the sine wave driving pulse generator 12 are cut off for a specified period, and driving pulses wherein sine wave driving pluses and a trapzoidal wave driving pluses are mixed are generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive pulse generator, and more particularly to a drive pulse generator suitable for driving a drive using an electromechanical transducer.

[0002]

2. Description of the Related Art In driving a member constituting a camera or other precision equipment, an electromechanical transducer, for example, a piezoelectric element generates an expansion / contraction displacement, transmits the expansion / contraction to a driving member, and frictionally couples to the driving member. A linear actuator and a rotary actuator configured to move a driven member via a member are known (see JP-A-4-69070 and JP-A-63-11074). .

FIG. 10 shows an example of a driving device applied to driving a zoom lens mounted on a camera, and a supporting member 102 for supporting a lens barrel 101 as a driven member.
Are fitted to the drive shaft 103 by slidable frictional contact. Also, the drive shaft 103
Is supported by the support portions 105 and 106 of the frame 107 so as to be displaceable in the axial direction. One end of the piezoelectric element 108 displaced in the thickness direction is fixed to the axial end of the drive shaft 103, and the other end of the piezoelectric element 108 is
7, the drive shaft 103 is displaced in the axial direction by the displacement of the piezoelectric element 108 in the thickness direction.

Reference numeral 104 denotes a leaf spring, which is slidably fitted to the support 102 by small screws (not shown).
10 is fixed from below in FIG. A bent portion 104a which is bent upward is formed at the center of the leaf spring 104, and this bent portion 104a is pressed against the drive shaft 103 to generate an appropriate frictional force at the contact portion. .

In the driving mechanism shown in FIG. 10, a driving pulse having a waveform composed of a gentle rising portion and a rapid falling portion following the gentle rising portion as shown in FIG.
Is applied to the piezoelectric element 10 at the rising portion of the drive pulse.
8 gradually expands in the thickness direction to cause displacement, and the drive shaft 103
Moves slowly in the direction of arrow a in the axial direction.

At this time, the frictional force between the drive shaft 103 and the sliding fitting portions 102a and 102b of the support 102 and the frictional force between the drive shaft 103 and the bent portion 104a of the leaf spring 104 are reduced.
If the force is not more than the force applied to the drive shaft 103 by the piezoelectric element 108, the support 102 moves in the direction of arrow a together with the drive shaft 23 in a state of being frictionally coupled to the drive shaft 103, and the lens barrel 101 is indicated by arrow a. Move in the direction.

On the other hand, in the rapid falling portion of the driving pulse,
Since the piezoelectric element 108 rapidly shrinks in the thickness direction, the drive shaft 103 moves rapidly in the axial direction in the direction opposite to the arrow a. At this time, the sliding shaft 102 is attached to the drive shaft 103.
The support member 102 supported by the first and second members 102a and 102b is provided with a sliding fit portion 1 between the drive shaft 103 and the support member 102 due to its inertial force.
The lens barrel 101 does not move because it overcomes the frictional force between the drive shaft 102a and 102b and the frictional force between the drive shaft 103 and the bent portion 104a of the leaf spring 104 and stays at that position.

By continuously applying the drive pulse having the above-described waveform (trapezoidal waveform) to the piezoelectric element 108, the lens barrel 101 can be continuously moved in a direction indicated by an arrow a (forward direction). In order to move the lens barrel 101 in the direction opposite to the arrow a (reverse direction), a drive pulse having a waveform consisting of a rapid rising portion and a gentle falling portion as shown in FIG. This can be achieved by applying a voltage to the piezoelectric element 108.

The speed control of a driving device for driving the lens barrel 101 and the like can be performed by thinning out driving pulses applied to the piezoelectric elements. That is, assuming that the driving speed at the time of driving with a continuous driving pulse train is V, if the driving pulse is thinned out from the driving pulse train at a predetermined ratio to lower the driving efficiency, the driving speed is also reduced according to the thinned ratio. , The target drive speed Vt can be obtained.

Specifically, for example, if the driving speed when driving by a continuous driving pulse train is V, the target speed Vt can be obtained by reducing the driving efficiency to m / k. , The continuous drive pulse train is divided into k pieces (for example, k = 5), and m (for example, m = 2) drive pulses are left from the drive pulse train, leaving (km) pulses (5 in the above example). When -2 = 3) is thinned out, the driving efficiency is reduced to m / k (2/5 = 0.4 in the above example), and the target speed Vt can be obtained.

FIG. 12 shows the above-mentioned example, in which a continuous drive pulse train is divided into five, and a pulse train is obtained by thinning out three pulses while leaving two (m = 2) drive pulses. FIG. 13 is a diagram illustrating an example of the relationship between the driving efficiency and the driving speed.

[0012]

As described above, the speed control of a driving apparatus using a conventional piezoelectric element is performed by thinning out driving pulses. This speed control method will be described below. It turned out that there was such an inconvenience.

A driving device using a piezoelectric element reciprocates a driving shaft at different speeds due to expansion and contraction displacement of the piezoelectric element at different speeds, and moves a driven member frictionally coupled to the driving shaft. When the element is gently displaced, it is frictionally coupled to the drive shaft and moves together with the drive shaft. When the piezoelectric element is rapidly displaced, it overcomes the frictional coupling force with the drive shaft and maintains a stationary state by inertia. That is, the driven member moves in a predetermined direction while repeatedly moving and stopping, and the driving speed in this case indicates an average driving speed obtained by repeating the movement and the rest.

Therefore, when the driving pulse applied to the piezoelectric element is not thinned out, the piezoelectric element, the driving shaft and the driven member of the driving device vibrate at the frequency of the driving pulse, but the frequency of the driving pulse is higher than the audio frequency. With this setting, the vibration sound does not become harsh and the generated mechanical vibration is not large.

However, when the drive pulse is thinned, first, there is a disadvantage that intermittently large mechanical vibrations having a frequency corresponding to the thinning cycle are generated in the piezoelectric element, the drive shaft, and the driven member. .

Second, even when the frequency of the drive pulse is set to be higher than the audio frequency, an unpleasant vibration sound is generated if the period of the thinning is within the audio frequency range.

Third, when the thinning rate of the driving pulse is increased to drive at a low speed, the speed unevenness is increased, and the unpleasant vibration sound is further increased.

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.

[0019]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. According to a first aspect of the present invention, a driving pulse is applied to an electromechanical transducer to generate an expansion and contraction displacement, and the generated displacement causes a driven element to be driven. A drive pulse generator suitable for a drive device for driving a member, comprising: a timing signal generator for generating a timing signal; an AC pulse generator for generating an AC pulse having a predetermined amplitude; and a controller. Generating the timing signal at a predetermined timing determined based on the driving speed information of the designated driven member, and outputting the output of a predetermined phase range of the AC pulse output from the AC pulse generating means to the timing signal. And a drive pulse generator for generating a drive pulse to be applied to the electromechanical transducer.

The alternating current pulse generated by the alternating current pulse generating means is an alternating current pulse composed of odd harmonics whose rising and falling portions are symmetrical in waveform. Specifically, it may be a triangular waveform pulse in which the rising and falling portions have symmetrical waveforms, or a trapezoidal waveform pulse in which the rising and falling portions have symmetrical waveforms.

Further, it is preferable that the control means interrupts the output of a predetermined phase range for a part or all of the AC pulses in units of a plurality of AC pulses.

According to a sixth aspect of the present invention, there is provided a driving pulse generator suitable for a driving device which applies a driving pulse to an electromechanical transducer to generate expansion and contraction displacement and drives a driven member by the generated displacement. And a first signal for generating a first pulse contributing to driving of the driven member in synchronization with the timing signal.
A pulse generating means for generating a second pulse not contributing to driving of the driven member in synchronization with the timing signal;
A pulse generation unit; and a control unit, wherein the control unit is configured to control the first pulse and the second pulse in accordance with a predetermined ratio determined based on drive speed information of a designated driven member.
Are sequentially selected and output to generate a drive pulse to be applied to the electromechanical transducer.

The first pulse generated by the first pulse generation means is an AC pulse having asymmetric rising and falling waveforms.

The second pulse generated by the second pulse generating means is an AC pulse composed of odd harmonics having symmetrical rising and falling waveforms. Specifically, it may be an AC pulse having a sine waveform, a triangular waveform pulse having symmetric rising and falling waveforms, or a trapezoidal waveform pulse having symmetric rising and falling waveforms.

According to a twelfth aspect of the present invention, there is provided a driving pulse generator suitable for a driving device which applies a driving pulse to an electromechanical transducer to generate expansion and contraction displacement and drives a driven member by the generated displacement. Signal generator, an AC pulse generator that generates an AC pulse of a predetermined amplitude in synchronization with the timing signal, and a controller, wherein the controller is constantly output from the AC pulse generator. When the AC pulse is output to the electromechanical transducer and the driven member is driven, at a predetermined timing determined based on the drive speed information of the specified driven member, output of a predetermined phase range of the AC pulse is performed. The drive pulse generator is characterized in that the driving pulse is cut off.

[0026]

Embodiments of the present invention will be described. First, the driving method of the present invention will be described. According to the present invention, two types of pulses, a driving pulse having a waveform that can move the driven member and a driving pulse having a waveform that cannot move the driven member, are set to 1 to 3 according to a desired moving speed. A drive pulse formed by combining a plurality of drive pulses is applied to an electromechanical transducer, for example, a piezoelectric element to control a drive speed. One of the drive pulses is controlled from a drive pulse train as in the case of a conventional drive speed control. Do not control the drive speed by thinning out the parts. Thereby, various inconveniences caused by thinning out the driving pulses can be solved.

First, the waveform of the driving pulse will be described. FIG. 1 is a diagram showing a waveform of a drive pulse. FIG. 1A shows a sine wave pulse, which is composed of a gentle rising portion and a gentle falling portion. When this pulse is applied to the piezoelectric element, since the magnitudes of the generated extension displacement and contraction displacement are equal, vibration is generated in the driven member, but the driven member cannot be moved. The drive pulse having the waveform shown in FIG. 1A is used when the driven member is stopped. In the following description, it is called a sine wave drive pulse.

FIG. 1B shows a drive pulse in which the gentle falling portion of the sine wave driving pulse shown in FIG. 1A is replaced by a rapid falling portion. Since the pulse has a rapid falling portion, it is basically the same as the drive pulse having the waveform shown in FIG. 11A described above as a conventional example.

FIG. 1C shows a drive pulse in which a part of the gentle falling portion of the driving pulse shown in FIG. 1A is replaced by a rapid falling portion. It has a rising part and a partly rapid falling part, and is similar to the driving pulse having the waveform shown in FIG. The driving speed becomes slow.

FIG. 1 (d) is a drive pulse in which the gentle rising portion of the sine wave driving pulse shown in FIG. 1 (a) is replaced with a rapid rising portion, and this pulse has a rapid rising portion and a gentle rising portion. Since the pulse has a falling portion, it is basically the same as the drive pulse having the waveform shown in FIG. 11B described above as a conventional example.

FIG. 1E is a drive pulse in which a part of a gentle rising portion of the driving pulse shown in FIG. 1D is replaced by a rapid rising portion, and this pulse is partially rapid. 1D, which is similar to the driving pulse having the waveform shown in FIG. 1D, but the driving speed of the driven member is reduced by the short time of the rapid rising portion. Become slow.

In the following description, the drive pulses having the waveforms shown in FIGS. 1B to 1E are collectively referred to as trapezoidal drive pulses.

The trapezoidal wave drive pulses shown in FIGS. 1B to 1D take the sine wave drive pulse shown in FIG. 1A as an input, and have a rapid falling portion or a rapid rise. In order to form the rising portion, the trapezoidal wave drive pulse can be obtained by turning off the output of the sine wave drive pulse at a predetermined timing or turning on the off output.

By appropriately combining the above-described sine wave drive pulse shown in FIG. 1A with the trapezoidal wave drive pulse shown in FIGS. 1B and 1C, the driven member is moved forward. Direction can be driven at a desired driving speed. Also, by appropriately combining the sine wave drive pulse shown in FIG. 1A and the trapezoidal wave drive pulse shown in FIG. 1D and FIG. (In the opposite direction) at a desired driving speed.

FIG. 2 is a block diagram showing a configuration of a drive pulse generating circuit capable of controlling the speed applied to a drive device using a piezoelectric element. The drive pulse generation circuit 10 includes a microprocessor (CPU) 11, a sine wave drive pulse generator 12, a switching unit 14, and a piezoelectric element drive unit 1.
5 and a piezoelectric element 16 connected to the piezoelectric element driving unit 15
Consists of The sine waveform drive pulse generator 12
This is a known waveform generator that generates a sine waveform shown in FIG.

FIG. 3 is a timing chart for explaining the operation of the driving pulse generating circuit 10. FIG. 3A shows a waveform output from the sine wave driving pulse generator 12, and FIG. ) Indicates a timing signal A output from the CPU 11. FIG. 3D shows an example of the timing signal B for cutting off the output of the sine wave drive pulse, and FIG.
Shows an output waveform in which a part of the sine wave driving pulse is cut off by the timing signal B shown in FIG.

FIG. 3F shows another example of the timing signal B for cutting off the output of the sine wave drive pulse.
FIG. 3E shows a waveform in which a part of the sine wave driving pulse is cut off by the timing signal B shown in FIG.

Next, the operation will be described with reference to FIGS. First, a case where the driven member is driven in the forward direction will be described. The sine waveform drive pulse generator 12 generates a predetermined sine waveform drive pulse (see FIG. 3A) in synchronization with the timing signal A (see FIG. 3B) output from the CPU 11, and performs switching. Output to the unit 14. Upon receiving the speed command signal C from an external device (not shown), the CPU 11 outputs a timing signal B (see FIG. 3D) for performing a shutoff command to the switching unit 14 at a timing corresponding to the commanded speed. The output of the drive pulse output from the sine waveform drive pulse generator 12 is cut off only during the period t1. Thereby, as shown in FIG. 3C, a drive pulse in which the sine waveform drive pulse and the trapezoidal wave drive pulse are mixed is applied to the piezoelectric element 16.

When the driven member is driven in the reverse direction,
When receiving a speed command signal C from an external device (not shown), the CPU 11 outputs a timing signal B (see FIG. 3 (f)) for performing a shutoff command to the switching unit 14 at a timing corresponding to the commanded speed, and The output of the drive pulse output from the waveform drive pulse generator 12 is cut off only during the period t2. As a result, as shown in FIG. 3E, a drive pulse obtained by mixing the sine waveform drive pulse and the trapezoidal wave drive pulse is applied to the piezoelectric element 16.

The driving speed and the mixing ratio of the trapezoidal wave driving pulse and the sine wave driving pulse will be described. The drive speed is controlled by using k drive pulses as one unit, and one unit is composed of a total of k trapezoidal drive pulses and n sine wave drive pulses (k = m + n). And

FIGS. 4A and 4C show a drive pulse train in this example. In this case, one unit of drive pulse is k trapezoidal drive pulses (m = k, n = 0), the maximum driving speed is obtained, and when one unit of driving pulse is composed of zero trapezoidal wave driving pulses (m = 0, n = k), the driving speed becomes zero. Then, the driving speed can be represented by the maximum driving speed V × (m / k). Here, the number k of drive pulses is (m + n),
(M / k) represents the driving efficiency. In addition, a period of one unit of the drive pulse including the k drive pulses is referred to as a control cycle here.

For example, when it is desired to set the driving speed Vt to 40% of the maximum driving speed V, the number of driving pulses included in one control cycle is set to k = 5, and the number of trapezoidal wave driving pulses becomes 2
(M = 2), and the number of sine wave drive pulses is 3 (n =
3) And the driving speed Vt is 40% of the maximum driving speed V.
Can be obtained.

FIGS. 4A and 4C show a drive pulse train in this example. FIG. 4A shows the first two drive pulses when the number of drive pulses per unit is k = 5. Example in which a pulse is a trapezoidal wave drive pulse (m = 2), and three drive pulses are subsequently a sine wave drive pulse (n = 3)
It is. In this case, the timing signal B for issuing the cutoff command is as shown in FIG.

FIG. 4C shows that, when the number of drive pulses included in one control cycle is k = 5, the first and third drive pulses are trapezoidal drive pulses (m = 2), This is an example (n = 3) in which the fourth and fifth drive pulses are sine wave drive pulses. In this case, the timing signal B for issuing the cutoff command is as shown in FIG.

Since the unevenness of the driving speed of the mixed pattern shown in FIG. 4C is smaller than that of the mixed pattern shown in FIG. 4A, the mixed pattern shown in FIG. Is more desirable. As the number of driving pulses included in one control cycle is increased, the variation in the mixing pattern of the trapezoidal wave driving pulse and the sine wave driving pulse can be set to a larger value. Can be set finely.

FIG. 5A shows the relationship between the drive efficiency (m / k) and the average drive speed V during the control cycle k. Both are approximately proportional, and the drive efficiency (m / k) is shown. k)
Is higher, the average driving speed V is higher. Therefore, by setting the drive efficiency (m / k) with respect to the value of the speed command signal C as shown in FIG. 5B and incorporating it in the program of the control circuit, the drive efficiency (m / k) is obtained as shown in FIG. In addition, an average driving speed V proportional to the speed command signal C can be obtained.

To switch the driving direction of the driven member, as described above with reference to FIG. 3, a timing signal B for issuing a shut-off command is output based on information indicating forward / reverse movement included in the speed command signal C. This can be achieved by changing the timing. That is, when the driven member is driven in the reverse direction, the CPU 11 performs the operation shown in FIG.
A timing signal B for issuing a cutoff command at the timing shown in FIG. 3F is output to the switching unit 14, and a trapezoidal wave drive pulse shown in FIG. 3E is generated. The drive pulse shown in FIG. 3E has a rising / falling portion opposite to the drive pulse shown in FIG. 3C for driving the driven member in the forward direction. It can be driven in the reverse direction.

In addition, the switching of the driving direction of the driven member is performed by the CPU 11 and the piezoelectric element driving unit 15 (FIG. 2) based on information indicating forward / reverse movement included in the speed command signal C.
), A switching signal D for inverting the electrodes of the piezoelectric element to which the drive pulse is applied is output, and the drive pulse is applied to the piezoelectric element in the opposite direction.

Thus, a driving pulse (sine wave driving pulse or trapezoidal wave driving pulse) synchronized with the timing signal A is always applied to the piezoelectric element, and a part of the driving pulse corresponds to the speed command signal C. Since only the trapezoidal wave driving pulse contributes to the driving of the driven member, the driven member can be driven at a desired driving speed, and the driving pulse is not thinned out to obtain the desired driving speed. Therefore, various inconveniences due to thinning out do not occur.

In the above-described embodiment, a sine wave drive pulse is used as a base pulse for generating a drive pulse for moving the driven member forward / backward and as a pulse for stopping the driven member. I have. However, the basic pulse is not limited to the sine wave driving pulse, but is a pulse that can make the driven member seem to be stationary, and by cutting off a part of the pulse, the inclination angles of the rising portion and the falling portion are reduced. Any pulse may be used as long as it has a waveform from which different trapezoidal drive pulses can be obtained. For example, a triangular pulse having the same inclination angle between the rising portion and the falling portion, or a trapezoidal pulse obtained by cutting off the top of the triangular pulse may be used. These triangular waves and trapezoidal waves consist of odd harmonics of the sine wave. Hereinafter, this will be described.

FIGS. 6A to 6C illustrate the formation of a drive pulse using a triangular wave pulse as a basic pulse. The timing signal A having a period t shown in FIG. 6B is used.
Generates a triangular wave pulse represented by an isosceles triangle in FIG. Then, by cutting off the rising portion or the falling portion of a part of the triangular wave pulse by the timing signal B for performing the cutoff command shown in FIG. 6C, the driving of the waveform shown by the solid line in FIG. A pulse can be obtained.

FIGS. 7A to 7D show the following.
FIG. 7B illustrates the formation of a drive pulse using a trapezoidal pulse as a basic pulse, and includes a timing signal A1 shown in FIG.
Generates a trapezoidal pulse. Timing signal A1
Is generated based on the timing signal A having the period t, the signal A1 also has the same period as the timing signal A. Then, the drive signal having the waveform shown by the solid line in FIG. 7A is obtained by cutting off the rising portion or the falling portion of the trapezoidal wave pulse by the timing signal B for performing the cutoff command shown in FIG. 7D. be able to.

Next, a second embodiment of the present invention will be described. In the second embodiment, a sine wave drive pulse and a trapezoidal wave drive pulse are separately generated, and these two drive pulses are combined based on the speed command signal C.

FIG. 8 is a block diagram showing a configuration of a drive pulse generation circuit applied to a drive device using a piezoelectric element according to the second embodiment. The drive pulse generation circuit 20
It comprises a microprocessor (CPU) 21, a sine waveform drive pulse generator 22, a trapezoidal wave drive pulse generator 23, a switching unit 24, a piezoelectric element drive unit 25, and a piezoelectric element 26 connected to the piezoelectric element drive unit 25. . The sine waveform driving pulse generator 22 may be a known waveform generator.

FIG. 9 is a timing chart for explaining the operation of the drive pulse generating circuit 20. FIG. 9A shows a waveform output from the trapezoidal wave drive pulse generator 23.
(B) shows a waveform output from the sine waveform drive pulse generator 22. FIG. 9C shows a timing signal A output from the CPU 21, and FIG.
1 shows a switching signal E output from the switch 1. FIG. 9E shows the waveform of the output trapezoidal wave drive pulse.

Next, the operation will be described with reference to FIG. 8 and FIG. Here, the case where the driven member is driven in the forward direction will be described. Sine wave drive pulse generator 22
9 generates a predetermined sine waveform driving pulse shown in FIG. 9B in synchronization with the timing signal A shown in FIG. 9C output from the CPU 21 and outputs it to the switching unit 24. Further, the trapezoidal wave driving pulse generator 23 is
A predetermined trapezoidal drive pulse shown in FIG. 9A is generated in synchronization with the timing signal A shown in FIG.

Upon receiving the speed command signal C from the external device, the CPU 21 alternately sets trapezoidal wave driving pulses and sine wave driving pulses at a ratio corresponding to the speed so that a speed corresponding to the commanded speed is obtained. A switching signal E is output to the switching unit 24 so as to be applied to the piezoelectric element 26. When the switching signal E is OFF, a sine wave driving pulse is output to the piezoelectric element driving unit 25. When the switching signal E is ON, A trapezoidal wave drive pulse is output to the piezoelectric element drive unit 25. As a result, a drive pulse in which the sine wave drive pulse and the trapezoidal wave drive pulse are mixed is applied to the piezoelectric element 26 according to the commanded drive speed as shown in FIG. 9E.

[0058]

As described above, according to the present invention, a driving pulse is applied to an electromechanical transducer to generate expansion and contraction displacement, thereby generating reciprocating vibrations at different speeds in a driving member, and frictionally coupling the driving member. In a driving device using an electromechanical transducer for driving a driven member in a predetermined direction, an output of a predetermined phase range of an AC pulse at a predetermined timing determined based on the driving speed information is used for controlling the driving speed. Cut off to form a drive pulse, or generate a first pulse that contributes to the driving of the driven member and a second pulse that does not contribute to the driving of the driven member, and are determined based on the driving speed information. A first pulse and a second pulse are sequentially selected and output based on a predetermined ratio to form a drive pulse, and the drive pulse is applied to an electromechanical transducer to control a drive speed. It is intended to.

According to the present invention, since the drive speed is not controlled by thinning out a part of the drive pulse train as in the case of the conventional drive speed control, various inconveniences caused by thinning out the drive pulses, that is, intermittent Large mechanical vibration occurs in the electromechanical transducer, the drive shaft and the driven member,
No harsh vibration sound is generated within the audible frequency range. Further, the present invention has excellent operational effects, such as a smaller variation in speed than when speed control is performed by thinning out drive pulses.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a waveform of a drive pulse according to the present invention.

FIG. 2 is a block diagram showing a configuration of a drive pulse generation circuit.

FIG. 3 is a timing chart illustrating the operation of a drive pulse generation circuit.

FIG. 4 is a diagram illustrating a mixed state of a trapezoidal wave driving pulse and a sine wave driving pulse.

FIG. 5 is a view for explaining the relationship between the drive efficiency and the average drive speed, the relationship between the speed command signal and the drive efficiency, and the relationship between the speed command signal and the average drive speed.

FIG. 6 is a diagram for explaining formation of a drive pulse using a triangular wave pulse as a basic pulse.

FIG. 7 is a view for explaining formation of a drive pulse using a trapezoidal wave pulse as a basic pulse.

FIG. 8 is a block diagram showing a configuration of a drive pulse generation circuit according to a second embodiment.

FIG. 9 is a timing chart illustrating the operation of the drive pulse generation circuit.

FIG. 10 is a perspective view showing an example of a driving device using a conventional piezoelectric element.

FIG. 11 is a diagram illustrating a waveform of a driving pulse used in a conventional driving device.

FIG. 12 is a diagram showing an example in which a drive pulse train is divided into a plurality of units and some pulses are thinned out.

FIG. 13 is a diagram illustrating an example of a relationship between drive efficiency and drive speed.

[Explanation of symbols]

 Reference Signs List 10 drive pulse generation circuit 11 microprocessor (CPU) 12 sine wave drive pulse generator 14 switching 15 piezoelectric element drive unit 16 piezoelectric element 20 drive pulse generation circuit 21 microprocessor (CPU) 22 sine wave drive pulse generator 23 trapezoidal wave pulse Drive pulse generator 24 Switching 25 Piezoelectric element driver 26 Piezoelectric element

Claims (12)

[Claims] 1. A driving pulse generator suitable for a driving device which applies a driving pulse to an electromechanical transducer to generate expansion and contraction displacement and drives a driven member by the generated displacement, wherein a timing signal for generating a timing signal is provided. Generating means, AC pulse generating means for generating an AC pulse having a predetermined amplitude, and control means, wherein the control means performs the above at a predetermined timing determined based on driving speed information of a designated driven member. Generating a timing signal, cutting off output of a predetermined phase range of the AC pulse output from the AC pulse generating means based on the timing signal, and generating a drive pulse to be applied to an electromechanical transducer. Drive pulse generator. 2. The drive according to claim 1, wherein the AC pulse generated by the AC pulse generating means is an AC pulse composed of odd harmonics whose rising and falling portions have symmetrical waveforms. Pulse generator. 3. The drive pulse generator according to claim 1, wherein the AC pulse generated by the AC pulse generator is a triangular waveform pulse having a symmetrical rising and falling waveform. 4. The driving pulse generating apparatus according to claim 1, wherein the AC pulse generated by the AC pulse generating means is a trapezoidal waveform pulse having a symmetrical rising and falling waveform. 5. The apparatus according to claim 1, wherein the control means interrupts an output in a predetermined phase range for a part or all of the AC pulses in units of a plurality of AC pulses.
The driving pulse generator according to the above. 6. A driving pulse generator suitable for a driving device that applies a driving pulse to an electromechanical transducer to generate expansion and contraction displacement and drives a driven member by the generated displacement, wherein a timing signal for generating a timing signal is provided. Generating means; first pulse generating means for generating a first pulse contributing to driving of the driven member in synchronization with the timing signal; and second generating means not contributing to driving of the driven member in synchronization with the timing signal. And a control means, wherein the control means controls the first pulse according to a predetermined ratio determined based on drive speed information of a designated driven member. And a second pulse sequentially selected and output to generate a drive pulse to be applied to the electromechanical transducer. 7. The drive pulse generating device according to claim 7, wherein the first pulse generated by the first pulse generating means is an AC pulse having asymmetric rising and falling waveforms. 8. The apparatus according to claim 7, wherein the second pulse generated by the second pulse generating means is an AC pulse composed of odd harmonics having symmetric rising and falling waveforms. The driving pulse generator according to the above. 9. The driving pulse generator according to claim 7, wherein the second pulse generated by the second pulse generator is an AC pulse having a sinusoidal waveform. 10. The driving pulse generating apparatus according to claim 7, wherein the second pulse generated by said second pulse generating means is a triangular waveform pulse having a symmetrical rising and falling waveform. . 11. The driving pulse generator according to claim 7, wherein the second pulse generated by the second pulse generating means is a trapezoidal waveform pulse in which the rising and falling portions have symmetrical waveforms. . 12. A drive pulse generator suitable for a drive device for applying a drive pulse to an electromechanical transducer to generate expansion and contraction displacement and driving a driven member by the generated displacement, wherein a timing signal for generating a timing signal is provided. Generating means, AC pulse generating means for generating an AC pulse having a predetermined amplitude in synchronization with the timing signal, and control means, wherein the control means constantly converts the AC pulse output from the AC pulse generating means into an electric machine. Output to the conversion element, and when driving the driven member, at a predetermined timing determined based on the driving speed information of the specified driven member, the output of a predetermined phase range of the AC pulse is cut off. Characteristic drive pulse generator.