JPH11206151A - Driving unit for oscillation actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to detect surely a ringing phenomenon and prevent it. SOLUTION: A driving unit includes an oscillation actuator 200 driven by mechanical oscillations by an electro-mechanical conversion element that changes electric energy to mechanical energy, driving units 2, 3, 4, and 5 for generating a driving signal for the oscillation actuator 200, and a control circuit 1 for instructing a driving method of the oscillation actuator 200 to the driving units 2, 3, 4, and 5. In addition, an oscillation detector 6 for detecting the oscillation of the oscillation actuator 200 is provided, and the revolutionary speed is reduced by the control circuit 1 when the oscillation detector 6 detects a given frequency of oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator driving device driven by utilizing the mechanical vibration of an electromechanical transducer for converting electrical energy into mechanical energy.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a general configuration of an annular vibration wave motor as an example of a vibration actuator. FIG. 7A is a cross-sectional view illustrating the vibration wave motor.
The vibration wave motor 200 is connected to the rotor 2
01a and the sliding member 201b constitute the moving element 201,
Similarly, the elastic body 202a and the piezoelectric body 2 adhered to each other.
02b together with the stator 202. The moving element 201 and the stator 202 are driven by being brought into pressure contact with a pressure unit (not shown).

FIG. 7B is a plan view showing the arrangement of electrodes of the piezoelectric body 202b. Electrodes 202b ₁ , 202b
₂ is an input electrode, having a phase difference of π / 2,
A sine wave voltage having a frequency determined for each vibration wave motor is applied. Electrode 202b ₃ is a common electrode to be grounded. Electrode 202b ₄ is an electrode which does not contribute to the excitation of the piezoelectric element 202b.

[0004] FIG. 7 (C) is a circuit diagram showing an equivalent circuit between the input electrode group 202b ₁ or 202b ₂ and the ground electrode 202b ₃ of the vibrating body 202b. This equivalent circuit is represented by a self-capacitance C ₀ and an L, C, R series resonance circuit connected in parallel with C ₀ . The current flowing through the L, C, and R series resonance circuits is called a motional current, and the magnitude thereof is considered to be proportional to the driving amount of the vibration wave motor 200, that is, the rotation speed. That is, the vibrating body 202b
By increasing the voltage value of the frequency voltage applied to the power supply or by bringing the frequency of the frequency voltage closer to the resonance frequency of the series resonance circuit, it is possible to increase the motional current and obtain a large driving amount.

Therefore, conventionally, two methods are known as methods for adjusting the driving amount of the vibration wave motor. The first method is to change the motional current by changing the voltage value of the frequency voltage while maintaining the frequency of the frequency voltage constant. The second method is to change the motional current by increasing or decreasing the frequency near the resonance frequency of the series resonance circuit without changing the voltage value of the frequency voltage.

Hereinafter, a drive circuit for driving the above-described vibration wave motor 200 will be described by taking as an example the case where the drive amount is adjusted by the second method. FIG. 8 is a block diagram showing a driving circuit of the vibration wave motor of FIG. A drive circuit of a conventional vibration wave motor includes a control circuit 1, a VCO (voltage controlled oscillator) 2, a phase shift circuit 5, and a piezoelectric body drive circuit 3.
(3A, 3B) and a power supply 4 and the like.
The control circuit 1 is a circuit that outputs a control signal of the voltage Vf to control the driving amount of the vibration wave motor 200, and its output terminal is connected to the VCO 2.

The VCO 2 is a circuit for outputting a logic signal Sa having a frequency corresponding to the voltage value of the input signal Vf, and its output terminal is connected to the phase shift circuit 5. Phase shift circuit 5
Is a circuit for converting the output logic signal Sa of the VCO 2 into two kinds of frequency signals having phases different from each other by π / 2,
The output is connected to the piezoelectric driving circuit 3 (3A, 3B).

The piezoelectric body driving circuits 3A and 3B include a phase shift circuit 5
Are circuits that amplify the voltage from the power supply 4 based on the frequency signal from the power source 4 and generate a sine wave voltage, and are connected to the electrodes 202b ₁ and 202b ₂ of the piezoelectric body 202b, respectively.

To the piezoelectric bodies 202b ₁ and 202b ₂ , sinusoidal voltages having frequencies near the resonance frequency determined by the stator 202 are inputted with a phase shift of π / 2 with respect to each other, and the elastic body 202a is excited. You. Due to the excitation, a progressive vibration wave is generated in the elastic body 202a, and the elastic body 202a drives the moving member 201 including the sliding member 201b and the rotor 201a which are in pressure contact with the elastic body 202a. The structure and operation of such a vibration wave motor are well known in Nikkei Mechanical 1983.2.28 or Japanese Patent Application No. 58-77380 by the present applicant.

Incidentally, the resonance frequency of the vibration wave motor 200 exists for each resonance order, and a resonance frequency band of the order showing the best drive characteristic among them is set as a drive frequency range of the vibration wave motor. The driving of the vibration wave motor can be performed in a resonance frequency band other than the resonance frequency band preset as the driving frequency range, but the driving directions are reversed in adjacent orders.

For example, in the vibrating body 202b shown in FIG.
Since the circumference of one polarization of the input electrode groups 202b ₁ and 202b ₂ is λ / 2, the input electrode groups 202b ₁ and 202b ₂
The circumference of 2b ₂ is 5λ, and the ground electrode 202b ₃ is 3λ / 4, and the detection electrode 202b ₄ is λ / 4.
Therefore, the circumference of the entire electrode is 11λ.

The wave number due to the polarization of the vibrating body 202b,
A state in which the wave numbers of the traveling vibration waves generated on the stator 201 when the vibration wave motor 200 is driven coincides, that is, in the example of FIG. 7, the eleventh resonance frequency band in which the eleven traveling waves are generated is , A resonance frequency band usually used as a driving frequency of the vibration wave motor.

FIG. 9 is a diagram showing the relationship between the drive frequency f and the drive amount N when the vibration wave motor is driven by the drive circuit of FIG. On the low frequency side and the high frequency side of the eleventh drive frequency range, there are a tenth drive frequency range and a twelfth drive frequency range. Vibration wave motor 20
The control circuit 1 performs voltage control in a range of Vf0 to Vfmax, where fb is a frequency at which 0 starts driving and fd is a driving frequency at which the vibration wave motor 200 handled at the control is the highest speed. The corresponding logic signal Sn
And outputs a frequency in the range of f0 to fmax.
For example, when rotating the vibration wave motor 200 at a rotation speed of vL, the drive frequency fD is fH. When rotating the vibration wave motor 200 at a rotation speed vH higher than vL, the driving frequency fD outputs fL that is a frequency lower than fH.

[0014]

One of the advantages of the above-described vibration wave motor is that it is quiet. However, an event called "squeal" may occur depending on the driving situation. The possible causes are as follows.

The first cause is a squeal that occurs because the vibration of the rotor (moving element) cannot follow the vibration of the stator (stator). This occurs because the mechanical quality factor Q of the stator is high. Generally, in order to rotate at a high speed, the mechanical quality factor Q is preferably higher. However, if a stator having a mechanical quality factor Q exceeding 100 is used, the rotor may not be able to follow. Therefore, the relationship between the two becomes unstable, and phenomena generally referred to as step-out, cogging, jump, and the like occur. The mechanical quality factor Q is a parameter indicating the sharpness of the mechanical resonance at the resonance frequency of the vibrator, and is calculated from the series resonance frequency and the parallel resonance frequency.

The second cause is that the piezoelectric body has cracks,
Even when the rotation between the rotor and the stator is forcibly stopped due to excessive load or freezing, the association between the rotor and the stator may be abnormal and cause a noise.

The third cause is a squeal caused by the poor flatness of the sliding surface of the rotor or the stator. During rotation,
When the protruding portions of the rotor and the stator are associated with each other, the pressing force concentrates on that portion. When the relative speed between the rotor and the stator increases, the change in the pressurizing energy increases and the noise appears.

As a means for preventing such a squeal, a method of detecting the natural vibration of the rotor by checking the step-out state from the vibration of the monitor electrode (Japanese Patent Laid-Open No. 6-1535).
No. 40) has been proposed. However, this method does not detect the squeal itself but detects a condition under which the first cause can occur. In other words, since a squealing phenomenon is detected as a squeal, a state in which no squeal actually occurs is detected as a squeal because it is a secondary detection means. In some cases, it was not possible to detect the squeal even when the sound was occurring.

An object of the present invention is to provide a vibration actuator driving device capable of accurately detecting a phenomenon called "squeal" and preventing the phenomenon.

[0020]

According to one aspect of the present invention, a vibration driven by utilizing mechanical vibration of an electromechanical transducer for converting electrical energy into mechanical energy is provided. An actuator (200) and a drive unit (3) for generating a drive signal for the vibration actuator
A driving control unit (1) for instructing the driving unit on a driving method of the vibration actuator, comprising: a vibration detection unit (6) for detecting vibration of the vibration actuator; The control unit is
When the vibration detection unit detects vibration of a predetermined frequency,
A vibration actuator driving device for instructing a change in the driving method.

According to a second aspect of the present invention, in the vibration actuator driving device according to the first aspect, the vibration detecting section comprises:
A vibration actuator drive device characterized in that the vibration detection range has a frequency band equivalent to a human audible frequency band.

According to a third aspect of the present invention, there is provided the first or second aspect.
5. The vibration actuator driving device according to claim 1, wherein the vibration detection unit is a microphone.

[0023] The invention of claim 4 is the invention of claims 1 to 3.
5. The vibration actuator driving device according to claim 1, wherein the vibration detection unit detects vibrations in a band other than a driving frequency of the vibration actuator.

According to a fifth aspect of the present invention, there is provided the first to fourth aspects.
4. The vibration actuator driving device according to claim 1, wherein the control unit reduces the speed of the vibration actuator when the vibration detection unit detects vibration of a predetermined frequency. Device.

[0025] The invention of claim 6 is the invention of claims 1 to 4.
5. The vibration actuator driving device according to claim 1, wherein the control unit changes a resonance mode of the vibration actuator when the vibration detection unit detects vibration of a predetermined frequency. It is a driving device.

[0026]

Embodiments of the present invention will be described below in further detail with reference to the drawings and the like. FIG. 1 is a block diagram showing an embodiment of a vibration actuator driving device according to the present invention. The present embodiment differs from the conventional driving device shown in FIG. 8 in that a vibration detecting device 6 is provided near the vibration wave motor 200, and the detection result is fed back to the control circuit 1. I have. Therefore, other circuit configurations are the same as those of the present embodiment and the conventional driving device shown in FIG. Therefore, only the operation of the vibration detection device 6 and a control method using the result will be described below, and the description of the same portions as those in the conventional example will be omitted as appropriate.

The vibration detecting device 6 is for detecting the phenomenon of "squeal" generated in the vibration wave motor 200.
What can detect the sound wave which is a human audible range is good, for example, a general microphone etc. can be used.
In the case where vibrations other than the audible range do not cause a problem as the use conditions of the vibration wave motor 200, the sensitivity band of the microphone is preferably 20 to 20 kHz. In addition, a sensitivity band other than the driving frequency of the vibration wave motor 200 may be provided.

FIG. 2 is a functional explanatory view showing in detail the vibration detecting device of the vibration actuator driving device according to the present embodiment. The vibration detection device 6 includes a microphone 61, a variable resistor 62 that determines a threshold value of a detection signal by dividing a power supply voltage, and a sound signal detected by the microphone 61 that exceeds a threshold voltage determined by the variable resistor 62. In this case, the comparator 63 that generates the abnormality detection signal Sn ′, and the abnormality detection signal Sn ′ from the comparator 63
Is temporarily held, and S is sent to the control circuit 1 until reset.
and a latch circuit 64 that keeps sending as an n signal.

The latch circuit 64 also has a terminal for inputting a reset signal Sr for resetting the latch. After the control circuit 1 recognizes the abnormality detection signal Sn ',
When a reset signal is sent, the latch circuit 64 is reset.

FIGS. 3, 4 and 5 are specific views showing an embodiment of a place where the microphone 61 is installed on the vibration wave motor 200, which is necessary for the driving device according to the present invention. In the embodiment shown in FIG. 3, the rotor 201 is supported by bearings 204, and the stator 202 is fixed to a stator fixing member 203. The microphone 61A is installed very close to the sliding member 201b. The microphone 61A is connected to the microphone fixing member 20.
5 is supported. The microphone 61A is connected to a comparator 63 outside the vibration wave motor 200 by a lead wire (not shown). Therefore, microphone 6
1A can detect "squeal" itself generated in the sliding portion.

In the embodiment shown in FIG. 4, the microphone 61B is mounted on the stator 202 so as not to interfere with the vibration of the stator 202.
It is installed at a position adjacent to. Similarly, the microphone 61B is connected to a comparator 63 outside the vibration wave motor 200 by a lead wire (not shown). In the present embodiment, the vibration of the stator 202 can be detected.
Abnormal vibration can be detected.

In the embodiment shown in FIG. 5, the microphone 61C is fixedly installed on the rotor 201, and the microphone 61C rotates together with the rotor 201. From the microphone 61C, a circular conductive pattern and a conductive brush (not shown)
It is connected to a comparator 60 outside the vibration wave motor 200 via a lead wire. In the present embodiment, since the microphone 61C goes around the circular portion formed by the sliding portion of the stator 202, even if the microphone is a small microphone, the “squealing” generated at a local position of the stator 202 can be efficiently performed. Can be detected. These three types of arrangements can be used in combination.

FIG. 6 is a flowchart showing a control operation of the vibration actuator driving device according to the present embodiment. In the present embodiment, the vibration wave motor 200
The case of moving by a predetermined amount will be described. The control circuit 1
The driving amount is input (step 1), and the current position is obtained (step 2). Then, in step 3,
It is determined whether or not the current position has reached the predetermined position (the remaining operating distance is 0). If the current position has not reached the predetermined position, the process proceeds to step 4. If the current position has reached the predetermined position,
Proceed to step 10 to stop the vibration actuator.

Next, the control circuit 1 calculates the rotation speed from the remaining distance to the predetermined position (step 4). Then, in step 5, it is determined whether or not a squeal detection signal (abnormality detection signal) Sn from the vibration detection device 6 has been detected, and if it has been detected, regardless of the designated rotation speed calculated in step 4, Proceeding to step 8, the squeal detection signal Sn
If no, go to step 6. Step 8
Then, the reset signal Sr is output, and the routine proceeds to step 9.

In step 6, the present rotational speed is compared with the instruction rotational speed calculated in step 4, and if the present rotational speed is higher than the instruction rotational speed, step 9 is executed.
If it is late, go to step 7. Step 7
Then, acceleration control is performed. In step 9, deceleration control is performed, and the process returns to step 2.

For example, when squealing occurs due to poor flatness of the vibration wave motor, the number of rotations at which squealing varies due to individual differences between the vibration wave motors. Even with such a vibration wave motor, it is possible to use the vibration wave motor at the maximum rotational speed at which the individual vibration wave motor does not squeal while maintaining the quietness which is a characteristic of the vibration wave motor.

(Other Embodiments) Without being limited to the above-described embodiments, various modifications and changes are possible, and these are also within the equivalent scope of the present invention. (1) The case where the speed control of the vibration wave motor is performed by controlling the drive frequency has been described, but the same applies to the case where the control is performed by changing the voltage. (2) The annular vibration wave motor has been described, but the technical idea according to the present invention can also be applied to a linear vibration wave motor. (3) Although each function has been described using circuit elements, a microcomputer or the like that performs the same function may be used. (4) Although the example in which the drive speed is reduced when the squeal is detected has been described, the vibration mode may be changed to the vibration mode of a different order described in FIG.

[0038]

As described above in detail, according to the present invention, the actual vibration generated from the device equipped with the vibration actuator is detected and the driving method is changed, so that the generation of the vibration is reliably prevented. There is an effect that it can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a vibration actuator driving device according to the present invention.

FIG. 2 is a circuit diagram showing a vibration detecting device of the vibration actuator driving device according to the embodiment.

FIG. 3 is a specific diagram showing an embodiment of a place where a microphone 61A required for a driving device according to the present invention is installed on a vibration wave motor 200.

FIG. 4 is a specific diagram showing an embodiment of a place where the microphone 61B required for the drive device according to the present invention is installed on the vibration wave motor 200.

FIG. 5 is a specific diagram showing an embodiment of a place where a microphone 61C required for a driving device according to the present invention is installed on a vibration wave motor 200.

FIG. 6 is a flowchart illustrating a control operation of the vibration actuator driving device according to the embodiment.

FIG. 7 is a schematic view illustrating a general configuration of a vibration actuator.

FIG. 8 is a block diagram showing a driving device for driving the vibration actuator of FIG. 7;

FIG. 9 is a diagram for explaining drive characteristics of the vibration actuator of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control circuit 2 VCO 3 Piezoelectric body drive circuit 4 Power supply 5 Phase shift circuit 6 Vibration detection device 61 Operational amplifier 63 Resistance 64 Capacitor

Claims (6)

[Claims] A vibration actuator that is driven by using mechanical vibration of an electromechanical transducer that converts electrical energy into mechanical energy; a driving unit that generates a drive signal for the vibration actuator; and the vibration actuator. A drive control unit for instructing the drive unit on the drive method of the vibration actuator, comprising: a vibration detection unit configured to detect a vibration of the vibration actuator; A vibration actuator driving device for instructing a change in the driving method when vibration of the vibration actuator is detected. 2. The vibration actuator driving device according to claim 1, wherein the vibration detection unit has a vibration detection range having a frequency band equivalent to a human audible frequency band. 3. The vibration actuator driving device according to claim 1, wherein the vibration detection unit is a microphone. 4. The vibration actuator driving device according to claim 1, wherein the vibration detection unit detects vibration in a band other than a driving frequency of the vibration actuator. Vibration actuator drive device. 5. The vibration actuator driving device according to claim 1, wherein the control unit is configured to control the vibration actuator when the vibration detection unit detects vibration of a predetermined frequency. A vibration actuator driving device characterized in that the speed is reduced. 6. The vibration actuator driving device according to claim 1, wherein the control unit controls the vibration actuator when the vibration detection unit detects vibration of a predetermined frequency. A vibration actuator driving device for changing a resonance mode.