JPH10174468A - Oscillatory wave device driver and equipment provided with oscillatory wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable detection of a temperature fluctuation of a vibrator without using a temperature sensor by installing a temperature fluctuation detecting means, which detects a change in capacity of the vibrator by applying voltage of a frequency far away from the resonance frequency of the vibrator and then detects a temperature fluctuation. SOLUTION: Between a matching coil 6 and a drive electrode, an impedance element 12 for detecting current is inserted. A voltage difference across the impedance element 12 is detected by a differential amplifier 13, connected across it. By means of an amplitude-measuring equipment 14, the magnitude of a current can be detected as a voltage value. An A/D converter 15 inputs the voltage value into a microcomputer and therefore the microcomputer 11 is able to find the magnitude of the current. A difference in capacity component is difficult to know near the resonance frequency of a vibrator but can be detected as a difference in the magnitudes of currents at a frequency far from the resonance frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving apparatus for a vibration wave device such as a vibration wave motor and an apparatus having the vibration wave device.

[0002]

2. Description of the Related Art A vibrator is a basic structure of a vibrating wave device. A vibrator is brought into contact with a vibrator by pressurizing a contact body to move the vibrator relative to each other. Devices utilizing vibration waves, such as a vibration wave motor and a vibration wave linear motor which are relatively moved, have been developed and have been put to practical use by the present applicants. As is well known, this vibration wave device, for example, a vibration wave motor generates a high-frequency vibration in an electro-mechanical energy conversion element such as a piezoelectric element or an electrostriction element by applying an alternating voltage to the element. Is a new type of non-electromagnetic drive motor configured to extract the vibration energy as continuous mechanical motion. This operating principle is described in Japanese Patent Application Laid-Open No.
It is not described here because it is described in, for example, Japanese Patent No. 89375.

FIG. 8 is a side view of a conventional rod-shaped vibration wave motor and a wiring diagram for supplying a voltage to a piezoelectric element and extracting an output voltage from the piezoelectric element. Reference numeral 1 denotes a vibrating body constituting the rod-shaped vibrating wave motor, which is a combination of a piezoelectric element or an electrostrictive element and an elastic body.

The piezoelectric elements of the vibrating body 1 are composed of driving A-phase piezoelectric elements a1, a2 and B-phase piezoelectric elements b1, b2.
And the vibration detecting piezoelectric element s1. At this time, an A-phase applied voltage is applied to the metal plate as the electrode plate sandwiched between the A-phase piezoelectric elements a1 and a2, and a B-phase applied voltage is applied to the metal plate as the electrode plate sandwiched between the B-phase piezoelectric elements b1 and b2. Drives the piezoelectric element. At this time, the A-phase piezoelectric element a
1, a2 and B-phase piezoelectric elements b1 and b2 have GN
D potential. Similarly, one of the vibration detecting piezoelectric elements s1 (the B-phase side in FIG. 8) is at the GND potential, and is configured to extract a signal from the opposite side.

At this time, the signal extraction surface side of the vibration detecting piezoelectric element S is in contact with the metal block, but the block is insulated from the GND potential by an insulating sheet. Therefore, an output voltage corresponding to the vibration is directly obtained from the vibration detecting piezoelectric element s1. Then, the resonance frequency and the like are obtained from the magnitude of this voltage and the phase difference from the drive voltage.

FIG. 11 and FIG. 12 show such a vibration wave motor and its driving circuit.

[0007] Ad and BD are drive electrodes for applying an alternating voltage to the piezoelectric element or the electrostrictive element, 11 is a control circuit (hereinafter referred to as a control microcomputer) for driving and controlling the motor, Is an oscillator (for example, a VCO) that generates an alternating voltage, 3 is a 90 ° phase shifter, 4 and 5 are switching circuits that switch a power supply voltage with the alternating voltage from the oscillator 2 and the phase shifter 3, and 6 and 7 are motors. And a matching coil for matching impedance. 8 is a signal phase difference θ between the drive electrode Ad and the vibration detection electrode Sd.
This is a phase difference detector for detecting (A-S). Reference numeral 9 denotes a speed detector (for example, an encoder) for detecting the speed of the motor. Reference numeral 10 denotes a temperature sensor provided in a part of the motor.

When the vibration wave motor having such a configuration is driven at a high temperature or frequently, the temperature of the driving body rises to affect peripheral members, or the characteristics of the motor itself deteriorate due to heat. Occurs. As a countermeasure, a method has been considered in which a temperature sensor provided externally measures the temperature rise of the motor and controls the temperature so as not to exceed a predetermined temperature.

[0009]

As described above, in the above conventional example, if the temperature sensor is not used, the vibrating body does not stop even if the temperature of the vibrating body increases, which may affect the motor and peripheral members. Further, if a temperature sensor is provided as a countermeasure, there is a problem that the configuration of the peripheral circuit and the motor becomes large and the cost increases.

Further, if the temperature sensor is directly attached to the vibrator, the vibration will be adversely affected.

An object of the first invention according to the present application is to provide a driving apparatus of a vibration wave device which can detect a temperature change of a vibrating body without providing a temperature sensor.

An object of a second invention according to the present application is to provide a vibration wave device which can drive a vibrator without increasing the temperature of a vibrating body.

An object of a third invention according to the present application is to provide an apparatus having a vibration wave driving device capable of driving a driven body with a vibration wave without causing a temperature rise of the vibration body.

[0014]

According to a first aspect of the present invention for realizing the object of the first invention, an alternating signal is supplied to an electromechanical energy conversion element of a vibrator in which a driving wave is formed in a vibrating body. In the driving device of the vibration wave device having a driving circuit unit for applying the temperature, a change in capacitance of the vibrator is detected by applying a frequency voltage having a detection frequency apart from a resonance frequency of the vibrating body, and a temperature for determining a temperature change It is characterized by having a change determination means.

According to a second configuration for realizing the object of the first invention according to the present application, in the above-mentioned first configuration, when the temperature change determination by the temperature determination means is equal to or more than a predetermined value, the drive circuit unit And a stop means for instructing a stop of the drive. The third configuration for realizing the object of the first invention according to the present application is the first or second configuration described above.
Wherein the temperature determination means detects a change in capacitance of the vibrator from the magnitude of current at the detection frequency.

According to a fourth configuration for realizing the object of the first invention according to the present application, in the above-mentioned first or second configuration, the temperature determining means drives the capacitance of the vibrator at the detection frequency. It is characterized by detecting from the magnitude of the current consumption of the circuit section.

A fifth configuration for realizing the object of the first invention according to the present application is characterized in that, in the first configuration, the detection frequency is a non-driving frequency. A sixth configuration for realizing the object of the first invention according to the present application is characterized in that, in the first configuration described above, the temperature determination unit performs a determination operation before activating the drive circuit unit. Is what you do.

A seventh configuration for realizing the object of the first invention according to the present application is the above-described first configuration, wherein the temperature determining means performs the determination operation during the driving of the drive circuit unit for 1 second or less. It is characterized in that it takes less time.

An eighth configuration for realizing the object of the first invention according to the present application is characterized in that, in each of the above-described configurations, the temperature determining means is provided separately from the drive circuit section. .

A second aspect of the present invention according to the present invention is a drive characteristic changing means for shifting a drive frequency versus speed characteristic based on the determination information by the temperature determining means in the first configuration. It is characterized by having.

A configuration for realizing the object of the third invention according to the present application includes a driving device for the vibration wave device having each of the above configurations,
The driven body is driven by the vibration wave device.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a block diagram of a first embodiment in which the present invention is applied to a driving circuit of a rod-shaped vibration wave motor. In FIG. 1, the same members as those in the conventional example shown in FIG. 12 are denoted by the same reference numerals, and description thereof will be omitted.

The block diagram of the present embodiment shown in FIG. 1 is different from the block diagram of the conventional example shown in FIG. 12 in that a temperature sensor 10 is provided in the conventional example, whereas the temperature sensor 10 is provided in the present embodiment. That is, no part is required. In the present embodiment, the matching coil 6 and the driving electrode A
The impedance element 12 used for current detection is provided between the impedance element 12 and −d. Then, a voltage difference (corresponding to a current) is obtained by the differential amplifier 13 connected to both sides thereof. 14 is an amplitude measuring instrument (for example, RMS
-DC converter), whereby the magnitude of the current can be detected as a voltage value. Reference numeral 15 denotes an A / D converter for taking the voltage value into the microcomputer. The microcomputer 11 can obtain the magnitude of the current by the A / D converter 15.

FIG. 2 is a diagram showing the relationship between temperature and capacity change in a certain vibration wave motor. As can be seen from FIG. 2, the capacity of the motor changes almost linearly with temperature.

FIG. 3 shows frequency and current characteristics. I2 is I
This is a current characteristic when the capacitance component of the vibrating body is 1.5 times as large as 1. As can be seen from this figure, the difference in the capacitance component that was difficult to understand near the resonance frequency of the vibrating body can be detected as the difference in the magnitude of the current value at the frequency f2 far from resonance.

Accordingly, the control microcomputer 11 sets the frequency to f2 at the time of starting or at a certain moment during driving, and obtains a value corresponding to the current value from the output signal of the A / D converter.

If the value exceeds a certain value, the temperature of the motor rises and it is determined that the motor is in a dangerous state, and the motor is stopped.
By performing such control, it is possible to prevent the motor from being damaged.

In the present embodiment, when temperature is detected during driving, the frequency f2 must be set to 1 sec or less because smooth movement cannot be achieved unless the time for frequency f2 is set to 1 sec or less.

Further, in this embodiment, the current is obtained from the potential difference between both ends of the impedance element. However, the current may be detected by a current probe or a Hall element.

FIG. 13 is a flowchart showing the operation of the present embodiment. The driving procedure will be described below.

First, a frequency distant from the frequency at which the motor is driven is applied to the motor, and the impedance element 1
An initial check is performed to measure the capacity value of the motor from the voltage difference (corresponding to the magnitude of the current) between the two ends.

At this time, if it is determined that the value is larger than a certain capacity value, the motor is hot for some reason, it is determined that the motor is not suitable for driving, and the motor is not driven.

When the capacity value is less than a certain value, the motor can be driven as it is in an environment in which the motor can be driven.

Here, after a certain period of time has elapsed, the capacitance value is measured in the same manner as described above. If the motor is being driven at this time, the measurement is performed in the shortest possible time so as not to affect the driving of the motor.

At this time, if it is determined that the value is larger than a certain capacity value, it is determined that the motor is hot and it is inappropriate to drive the motor, the motor is stopped, and the temperature is lowered.

If the capacity value is equal to or less than a certain value, it is determined that the temperature rise of the motor is within an allowable range, and the motor is continuously driven. Then, the above operation is repeated until the motor is stopped.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
It is a block diagram of a circuit of a vibration wave motor showing the embodiment.

In this embodiment, the impedance element 16 is provided between the power supply and the switching circuit so that the power consumption of the switching circuit 4 can be determined.

Then, a voltage difference (corresponding to a current) is obtained by the differential amplifier 13 connected to both ends. Since the power supply voltage is almost constant, power consumption can be obtained from the magnitude of the current obtained by the A / D converter 15.

FIG. 5 shows the frequency and the power consumption characteristics of the switching circuit. Pi2 is a power consumption characteristic when the capacitance component of the vibrating body is 1.5 times that of Pi1. As can be seen from this figure, the difference in the capacitance component that was difficult to understand near the resonance frequency of the vibrating body was changed to the frequency f2 apart from resonance.
Can be detected as a difference in power consumption.

Accordingly, the control microcomputer 11 sets the frequency to f2 at the time of starting or at a certain moment during driving, and obtains a value corresponding to the current value at that time from the output signal of the A / D converter.

When the value exceeds a certain value, the temperature of the motor rises and it is determined that the motor is in a dangerous state, and the motor is stopped.

By performing such control, it is possible to prevent the motor from being damaged.

In the case of the first embodiment, an amplitude measuring device is required to measure the current (AC), but in the present embodiment, only the current (DC) need be measured, so that the amplitude measuring device is not required. .

In this embodiment, the impedance element 16 is provided on the power supply side of the switching circuit 4. However, the impedance element 16 may be provided between the power supply side of the switching circuit 5 or the place where the power supply sides of the switching circuits 4 and 5 are connected.

(Third Embodiment) FIG. 6 is a block diagram showing a circuit of a vibration wave motor according to a third embodiment of the present invention.

In this embodiment, an oscillator 17 used for capacitance detection and a switching circuit 1 for switching its signal
8 are provided separately. The switching circuit 4 for driving the piezoelectric element, which is connected to the switching circuit 18 for detecting the capacitance, is connected to the output of the oscillator 2 'so that the two transistors shown at the top and bottom in the figure are turned off and high impedance can be obtained. Features have been added.

First, since the motor is not driven when detecting the capacitance, the switching circuits 4 and 5 are turned off. At this time, the two transistors constituting the switching circuit 4 are turned off and become high impedance. Here, the oscillator 17 outputs a frequency distant from the resonance frequency of the vibrator, the piezoelectric element is driven by the switching circuit 18, and the power consumption at that time is obtained in the same manner as described in the second embodiment. Detect temperature.

Next, when driving the motor, the oscillator 17 outputs an output signal to the switching circuit 18 so that the two transistors constituting the switching circuit 18 are turned off and the impedance becomes high. Then, the switching circuit 18 has no effect on the driving of the motor.

According to the circuit configuration and control method of this embodiment, when the motor is driven, the impedance element 1
No power is consumed by flowing a current through the power supply 6, so that power consumption can be reduced.

(Fourth Embodiment) FIG. 7 shows a fourth embodiment of the present invention.
1 is a circuit block diagram of a vibration wave motor according to an embodiment.

In this embodiment, a comparator 19 is used instead of the A / D converter 15 used in each of the above embodiments. A voltage value (V-set) corresponding to power consumption when the temperature rises and becomes dangerous is set in one input of the comparator 19. When the temperature does not rise normally, since the power consumption at the frequency f2 is small, a Lo signal is output to the microcomputer 11 without exceeding the comparator level. When the temperature of the motor rises due to continuous driving or the like and the temperature becomes dangerous, the capacitance value increases, the power consumption at the frequency f2 increases, and exceeds the comparator level. Then, the output of the comparator changes from Lo to Hi and notifies the control microcomputer that the temperature has risen to a dangerous temperature. Then, the control microcomputer determines that the state is dangerous, and stops the motor.

According to the circuit configuration of this embodiment, the comparator can be used instead of the A / D converter, so that the cost can be reduced and the number of signal lines to the control microcomputer can be reduced to one.

(Fifth Embodiment) FIG. 8 shows a fifth embodiment of the present invention.
1 is a circuit block diagram of a vibration wave motor according to an embodiment.

In this embodiment, the output of the differential amplifier 13 is input to the signal sample and hold circuit 20, and the output is input to the differential amplifier 21. A frequency control signal from the control microcomputer 11 is applied to the other end of the differential amplifier 21. The sample and hold circuit 20 includes a control microcomputer 1
A signal for controlling the hold timing from 1 is added.

FIG. 9 shows the temperature and frequency-rotation speed characteristics of the vibration wave motor. As can be seen from FIG. 9, the frequency of the vibration wave motor gradually increases as the frequency is reduced, and rapidly decreases after a certain frequency. Therefore, the drive frequency of the motor must be equal to or higher than the frequency at which the rotation speed suddenly decreases. Hereinafter, the present embodiment will be described with reference to FIG.

When the temperature of the motor is 25 ° C., the signal supplied from the control microcomputer to the oscillator 2 is set to have a frequency in a range (for example, Δf1) higher than the above-mentioned rotation decreasing frequency. At this time, the sample and hold circuit 20 is at 25 ° C.
The output voltage of the differential amplifier 13 corresponding to the capacitance value is held.

Here, when the temperature of the motor rises to 60 ° C., the frequency-speed characteristic shifts to the higher frequency side. Therefore, if the frequency range does not change from Δf1, a rotation reduction phenomenon occurs.

This embodiment avoids this phenomenon.

First, when the temperature rises to 60 ° C., the capacity of the motor increases, so that the output signal of the differential amplifier 13 at a frequency apart from the resonance frequency of the motor also increases. The control microcomputer holds the value in the sample and hold circuit 20. Since the signal is input to the differential amplifier 21, the signal of the control microcomputer is offset and input to the oscillator 2.

If the offset at this time is set so as to shift to the higher frequency side, the frequency range shifts to Δf2, and the portion where the rotational speed reduction phenomenon occurs is eliminated from the set frequency range. Therefore, even if the temperature of the motor changes, it is possible to always avoid the occurrence of the decrease in the rotation speed.

In the present embodiment, the rotation speed reduction phenomenon is avoided, but it may be used to avoid other problems.

In the above embodiment, a rod-shaped vibration wave motor is used as an example of the vibration wave device. However, the present invention is not limited to this. May be moved with respect to the stator, the vibrator and the contact body may be moved relative to each other, or the vibrator may be used as a conveying device for conveying a sheet, a card, or the like. Any material that excites vibration in the elastic body can be applied.

(Sixth Embodiment) FIG. 10 shows a driving device using a vibration wave motor according to the present invention.

The basic structure of this rod-shaped vibration wave motor is the same as that of the conventional example, but the drive is controlled by the circuit for detecting a temperature rise shown in the above embodiment.

A gear f integrated with the vibration wave motor meshes with an input gear GI of the gear transmission mechanism G, and an output gear GO of the gear f is formed on a lens holding member H holding the lens L1. It is engaged with HI. The lens holding member H is helicoid-coupled to the fixed cylinder K, and is driven to rotate by the driving force of the vibration wave motor via the gear transmission mechanism G to perform a focusing operation.

The operations of the above-described second to sixth embodiments are substantially the same as those of the flowchart of the first embodiment shown in FIG. 13 except for the method of detecting the capacitance value.

[0068]

According to the first aspect of the present invention, it is possible to detect a change in the temperature of the vibrator without providing a dedicated temperature sensor, so that the circuit can be reduced in size and the cost can be reduced. .

According to the invention of claim 2, in addition to the effect of claim 1, it is possible to prevent the temperature of the vibrator from rising.

According to the third and fourth aspects of the present invention, it is possible to detect a temperature change of the vibrator with a simple configuration using an existing drive circuit unit.

According to the fifth and sixth aspects of the present invention, the temperature change state of the vibrator can be detected in advance before the vibration wave device is driven, and the occurrence of trouble due to abnormal temperature rise can be prevented.

According to the seventh aspect of the present invention, the determination operation can be performed without affecting the driving even during the driving of the vibration wave device.

According to the eighth aspect of the present invention, since the temperature judging means is provided separately from the driving circuit section, the degree of freedom of arrangement of the temperature judging means is increased, and the temperature judging means can be added to the existing driving circuit section. Can be.

According to the ninth aspect of the present invention, it is possible to suppress the temperature rise of the vibrator and to drive the vibrator always in a stable state.

According to the tenth aspect of the present invention, the above-described effects are obtained, a failure due to abnormal temperature rise can be prevented, and the driven body can be driven stably.

[Brief description of the drawings]

FIG. 1 is a block diagram of a circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a temperature and a capacity change in a certain vibration wave motor.

FIG. 3 is a diagram showing frequency and current characteristics.

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

FIG. 5 is a diagram showing frequency and power consumption characteristics.

FIG. 6 is a block diagram of a circuit according to a third embodiment of the present invention.

FIG. 7 is a block diagram of a circuit according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram of a circuit according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing temperature and frequency-rotation speed characteristics.

FIG. 10 is an apparatus diagram using the vibration wave motor of the present invention.

FIG. 11 is a side view of a conventional rod-shaped vibration wave motor and a wiring diagram of voltage supply and output voltage extraction of a piezoelectric element configured therein.

FIG. 12 is a block diagram of a conventional circuit.

FIG. 13 is a flowchart showing the operation of the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Oscillator 2, 17 ... Oscillator 3 ... Phase shifter 4, 5, 18 ... Switching circuit 6, 7 ... Matching coil 8 ... Phase difference detector 9 ... Speed detecting means 10 ... Temperature sensor 11 ... Control microcomputer 12, DESCRIPTION OF SYMBOLS 16 ... Impedance element 13 ... Differential amplifier 14 ... Amplitude measuring device 15 ... A / D converter 17 ... Comparator 20 ... Sample hold circuit 21 ... Differential amplifier Ad, A'-d, Bd ... Driving electrode

Claims (10)

[Claims] 1. A driving apparatus for a vibration wave device having a driving circuit section for applying an alternating signal to an electro-mechanical energy conversion element of a vibrator in which a driving wave is formed in a vibrating body, wherein the driving circuit is separated from a resonance frequency of the vibrating body. A driving device for the vibration wave device, comprising: a temperature change determining unit that detects a change in capacitance of the vibrator by applying a frequency voltage having the detected frequency, and determines a temperature change. 2. The drive of the vibration wave device according to claim 1, further comprising a stop unit for instructing the drive circuit unit to stop driving when the temperature change judgment by the temperature judgment unit is equal to or more than a predetermined value. apparatus. 3. The driving apparatus for an oscillating wave device according to claim 1, wherein said temperature determining means detects a change in capacitance of said vibrator from a magnitude of a current at said detection frequency. 4. The driving apparatus according to claim 1, wherein said temperature judging means detects the capacitance of said vibrator from the amount of current consumed by said driving circuit at said detection frequency. apparatus. 5. The driving apparatus according to claim 1, wherein the detection frequency is a non-driving frequency. 6. The driving apparatus according to claim 1, wherein the temperature determination unit performs a determination operation before activating the drive circuit unit. 7. The temperature determination device according to claim 1, wherein the determination operation during driving of the drive circuit section is performed for 1 second.
A driving device for a vibration wave device, wherein the driving time is shorter than ec. 8. The driving device for an oscillatory wave device according to claim 1, wherein the temperature determining unit is provided separately from the driving circuit unit. 9. The driving device for an oscillatory wave device according to claim 1, further comprising a driving characteristic changing unit that changes a driving frequency versus a speed characteristic based on the judgment information by the temperature judging unit. 10. A device having a vibration wave device, comprising the driving device for the vibration wave device according to claim 1, wherein the driven body is driven by the vibration wave device. .