JP2003033057A - Position detector for oscillatory actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which can detect the position of a mover shifted by an oscillatory actuator without using a precise encoder. SOLUTION: This position detector detects the amplitude of oscillation from the output of a piezoelectric element provided in the oscillator, and converts it into velocity information with specified arithmetic processing and integrates it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for performing position control using a vibration type actuator.

[0002]

2. Description of the Related Art Conventionally, as in JP-A-9-84365, a vibration amplitude is detected, this value is integrated, and the result is controlled as a position. In general USM position control, a position sensor such as a rotary encoder is used to detect the position, and the drive frequency and voltage are changed to perform the position control. Further, in Japanese Patent Laid-Open No. 4-261378, the vibration amplitude is detected, this value is integrated, and when the integrated value reaches a predetermined value, the vibration type actuator is stopped.

[0003]

Generally, an expensive position sensor is required for position control. Further, even when the vibration is detected and integrated, it is difficult to detect the position with high accuracy due to variations in the vibration detection sensitivity due to individual differences of the motor and fluctuations in the vibration detection sensitivity due to temperature changes. Further, in the above-mentioned conventional example, the vibration amplitude is proportional to the speed information, but when the amplitude is actually small, there is a dead zone in which the motor does not rotate, which causes a problem that an error occurs.

[0004]

[Means for Solving the Problems] To achieve the above object,
In claim 1, a moving position or a moving amount for a vibration type actuator that applies a frequency signal to an electro-mechanical energy conversion element provided in a vibrating body to obtain a driving force and perform relative movement with an object. In the detection device, a vibration detection unit that detects the vibration amplitude of the vibrating body, a speed information conversion unit that obtains speed information from amplitude information based on the detected vibration amplitude, and a position or position that integrates the converted speed information. Integral calculation means for detecting the amount of displacement is provided. In the second aspect, the converting means obtains the speed information by multiplying a value obtained by subtracting a predetermined value from the vibration amplitude information by a predetermined proportional constant. According to a third aspect of the present invention, displacement amount information forming means for forming information corresponding to a displacement amount by being displaced by the driving force of the actuator, speed information is obtained from the information from the forming means, and the speed information is obtained by the obtained speed information. The proportional constant is corrected. According to a fourth aspect of the present invention, displacement amount information forming means for forming information according to the displacement amount by being displaced by the driving force of the actuator is provided, and the output of the integral calculating means is corrected by the information from the forming means. Is.
According to a fifth aspect of the present invention, when the difference between the information from the displacement amount information forming means and the information according to the displacement amount detected by the integral calculating means is a predetermined value or more, the output of the calculating means is converted into the information from the forming means. It was changed. According to a sixth aspect of the present invention, displacement amount information forming means for forming information according to a displacement amount by being displaced by the driving force of the actuator, speed information is obtained from information from the forming means, and the speed information is obtained according to the obtained speed information. The speed information of the speed information converting means is corrected. According to a seventh aspect of the present invention, at the time of starting or reversing the vibration type actuator, the integration of the integration calculating means is not performed for a predetermined time or a predetermined number of drive pulses, or until a predetermined vibration amplitude is reached. It is a thing. In the eighth aspect, when the vibration type actuator is reversed, the drive voltage is switched so that the vibration type actuator reverses after the vibration amplitude becomes smaller than the predetermined amplitude. The movement position or movement for a vibration type actuator for applying a frequency signal to an electro-mechanical energy conversion element provided on a vibrating body to obtain a driving force and to move relative to an object. In the quantity control device, a vibration detecting means for detecting the vibration amplitude of the vibrating body, a speed information converting means for obtaining speed information from amplitude information according to the detected vibration amplitude, and a position by integrating the converted speed information. Alternatively, an integral calculation means for detecting the displacement amount, a comparison means for comparing the integration result of the integration calculation means with a desired target position, and a control means for controlling the vibration type actuator based on the comparison result are provided. According to the tenth aspect, the movement amount at the time of the stop operation is calculated based on the vibration amplitude immediately before the stop or the speed information obtained from the conversion means, and the stop operation is started from the front of the target position by the movement amount. It is a thing. According to claim 11, in a photographing device having a lens for performing focus control using a vibrating actuator composed of a vibrating body and a moving body that comes in contact with the vibrating body, a vibration detecting means for detecting vibration of the vibrating actuator and a speed of the vibration. Conversion means for converting into information, integral calculation means for detecting the position by integrating the converted speed information, comparison means for comparing the integration result with a desired target position, and controlling the vibration type actuator based on the comparison result. The control means, the position detection means for directly or indirectly detecting the position of the focus control lens, and the correction means for correcting the integration result according to the position of the lens and the integration result are provided. According to a twelfth aspect of the present invention, the detecting means detects a value corresponding to a positional deviation between the image forming position of the object to be photographed and the recording member or the image pickup section. That is, the integral operation of the integral calculating means is not performed until the vibration amplitude reaches a predetermined vibration amplitude.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) FIG. 1 is a block diagram showing a first embodiment, and 1 and 2 are electro-mechanical energy conversion elements provided for driving a vibration type actuator. (Hereinafter, referred to as a piezoelectric element.) By applying an AC voltage to the vibrating body, two standing vibrations are generated in the vibrating body, and the vibrating body and the vibrating body (not shown) are pressed against the vibrating body. The vibration type actuator is configured to move relative to the body. Piezoelectric element 1 and piezoelectric element 2
Are applied with alternating voltages 90 ° out of phase with each other to generate vibrations 90 ° out of phase in the vibrating body and to generate progressive vibration waves on the vibrating body. There is. Reference numeral 3 denotes a piezoelectric element for detecting the vibration of the vibrating body, which is arranged on the vibrating body so as to detect the standing vibration generated by the piezoelectric element 1 on the vibrating body. Reference numeral 4 is a drive pulse control means for generating an AC signal for driving the vibration type actuator. During driving, until the vibration amplitude of the vibrating body exceeds a first predetermined vibration amplitude,
Two-phase pulse signals whose phases are shifted by 90 ° are output in a predetermined cycle. Reference numerals 5 and 6 are half-bridge circuits for converting the two-phase pulse signals into voltage amplitudes for driving the above-mentioned vibration type actuators. A voltage of 10V is applied. Reference numeral 7 is a current detection amplifier for detecting the output current of the piezoelectric element 3 for detecting the vibration of the vibrating body.
The output proportional to the vibration speed of the mass point of the vibrating body is detected. Since the amplitude of the vibration velocity is also proportional to the vibration amplitude,
This is also used as the vibration amplitude. Further, the output of the current detection amplifier 7 is configured to superimpose a predetermined offset voltage. Reference numeral 8 denotes a Schmitt trigger input inverter for converting the vibration velocity signal into a pulse signal, which detects the phase information by converting the vibration velocity signal into a pulse signal.
Reference numeral 9 denotes an AC-DC converting means for detecting the amplitude of the vibration velocity signal, which detects the vibration amplitude of the vibrating body. 10
Is a speed conversion means for converting the vibration amplitude signal which is the output signal of the AC-DC conversion means 9 into speed information, 11 is a code switching means for switching the sign of the speed information, and 12 is the speed information output by the code switching means 11. Integral calculation means 13, 13 is a comparison means for comparing the output of the integration calculation means 12 with a target position (not shown), and 14 is a PI for calculating PID of the comparison result of the comparison means 13 and outputting it to the drive pulse control means.
D calculation means.

Here, a brief description will be added to the characteristics of the output signal of the current detection amplifier 7. The signal detected by the piezoelectric element 3 represents the state of standing vibration generated by being excited by the piezoelectric element 1 among vibrations excited on a vibrating body (not shown). Due to this standing vibration, strain is generated on the attachment surface of the piezoelectric element 3, and charges proportional to the amount of strain are generated on the electrodes of the piezoelectric element 3. The amount of this distortion corresponds to the vibration amplitude of the vibrating body (not shown). As a result of the charge proportional to the amount of distortion being charged in the equivalent capacitance of the piezoelectric element 3, if the output of the piezoelectric element 3 is taken out as a voltage, The vibration displacement signal of the standing vibration excited by the vibration of the element 1 can be taken out. On the other hand, in this embodiment, the current output from the piezoelectric element 3 is detected by the current detection amplifier 7. Therefore, the output voltage of the piezoelectric element 3 is the current detection amplifier 7
Is converted into a voltage with a predetermined amplification factor of direct current, and a signal corresponding to the change in strain due to the standing vibration is detected. Therefore, as compared with the case where the output of the piezoelectric element 3 is detected by a voltage, a signal with a 90 ° phase advance is detected and its amplitude becomes a value substantially proportional to the amplitude of the standing vibration.

2 and 3 show the structure of the vibration type actuator. In FIG. 2, 100 is a vibrating body composed of one or more elastic members, 101 is a rotor that is brought into pressure contact with the vibrating body 100 by a pressurizing means (not shown), and 102 is the vibrating body 100.
Is a friction material that is bonded to the rotor 101 and is sandwiched between it and the rotor 101, 103 is a rotating shaft that is connected to the center of the rotor, and 104 is a piezoelectric body that is bonded to the vibrating body 100. Piezoelectric body 104
Has a shape shown in FIG. 3 and the surface is divided into a plurality of electrodes. In addition, this electrode has two driving electrode groups (104
-A, 104-b), one sensor electrode 104-c, and an empty electrode 104-d.
-A is referred to as A phase, 104-b is referred to as B phase, and 104-c is referred to as S phase. Empty electrode 104-
d is normally connected to GND. The S phase 104-c is arranged to detect the vibration of the A phase. The vibration type actuator shown in FIG. 2 generates a progressive vibration wave in the vibrating body 100 by applying an AC voltage having a temporal phase difference of 90 degrees to the A phase and the B phase, and vibrates the vibration force. The frictional force is transmitted to the rotor 101, which is in pressure contact with the body 100 through the friction material 102, to rotate the rotor 101. In this way, the vibration type actuator
By applying two AC voltages, the rotor 101 and the vibrating body 100 rotate relative to each other.

The operation of controlling the target position from the command means (not shown) will be described with reference to FIG. Therefore,
To control to the target position in a short time, increase the vibration amplitude of the vibrating body at high speed and move to the target position in a short time.
Vibration must be rapidly damped near the target position and stopped at the target position. Therefore, first, a case where the vibration amplitude is increased in the shortest time will be described. In order to vibrate the vibration amplitude so as to increase in the shortest time, the vibration force may be applied in a phase advanced by 90 ° with respect to the vibration displacement. Therefore,
The vibration is performed by utilizing the fact that the output signal of the current detecting means 7 is a signal which is 90 ° in phase with respect to the vibration displacement of the standing vibration when the piezoelectric element 1 vibrates. The drive pulse control means 4 detects the phase information of this signal from the output signal of the inverter 8, and the signal phase is detected by the PID calculation means 14
The pulse voltage is supplied to the piezoelectric element 1 via the half bridge circuit 5 by changing the timing of the output pulse in accordance with the output signal of. Here, the operation at startup will be described. Since the output of the PID calculating means 14 has a vibration amplitude of 0 at the initial stage of startup, the output of the AC-DC converting means 9 is 0.
Is. Therefore, the output of the speed conversion means 10 is 0, and the output of the integral calculation means 12 is also 0. This is the comparison means 13
Then, the result of comparison with the target position becomes a positive value, and the output signal of the PID calculation means 14 increases. Here, in the drive pulse control means 4, a phase delayed from the phase (AA) of the output signal of the inverter 8 by a time corresponding to a value obtained by subtracting a value corresponding to the predetermined time T1 from the output of the PID calculation means 14. Generate the signal. However, if the result of subtracting T1 is positive, the output signal of the inverter 8 is output as it is. Therefore, when the difference between the target position and the output of the integral calculating means 12 is large, the result obtained by subtracting the value corresponding to T1 becomes a positive value, the vibration is performed in the phase of the output signal of the inverter 8, and the vibration amplitude is high speed. Will increase. Next, when the output of the integration calculation means 12 approaches the target position, the output signal of the PID calculation means 14 approaches 0, and the result of subtracting the predetermined time T1 becomes a negative value, and the output signal of the inverter 8 becomes negative. A signal delayed by a time corresponding to the magnitude of the negative value with respect to the phase of is output to the half bridge circuit 5. Then, finally, it is excited at the phase of the exciting force for stopping the vibration at the highest speed (exciting force delayed by 90 ° with respect to the vibration displacement), and the vibration amplitude becomes equal to or less than the second predetermined vibration amplitude. Excitation is performed until the vibration amplitude is reached, and when the vibration amplitude reaches the second predetermined vibration amplitude or less, the drive voltage is fixed and the vibration is stopped. Even during this operation, the integration calculation means 12 continues to integrate the speed information output from the speed conversion means 10 until the vibration amplitude reaches the third predetermined vibration amplitude or less. The speed conversion means 10 is A
The vibration amplitude information is converted into velocity information by subtracting a predetermined level from the signal level output from the C-DC converting means 9 and multiplying it by a predetermined coefficient, and the output is set to 0 when the operation result is negative. It is configured. By doing so, when the vibration amplitude is smaller than the third predetermined vibration amplitude, the output of the integration calculation means 12 does not change, and the operation equivalent to not performing the integration is performed. Although the deceleration is performed in this manner, the deceleration is not in time and the integral calculation means 12
If the output exceeds the target position and exceeds the predetermined displacement amount, the pulse control means 4 controls that the vibration amplitude information, which is the output of the AC-DC conversion means 9, becomes smaller than the second predetermined vibration amplitude. After waiting, the phase difference between the signal PA and the signal PB is switched from 90 ° to −90 ° and a code switching command is output to the code switching means 11. Then, the vibration amplitude gradually increases, and when the vibration amplitude becomes larger than the third predetermined vibration amplitude, the sign is reversed. Therefore, the integral calculation means 12 integrates this, so that the integral calculation means 12 once exceeds the position command. Of the vibration type actuator again approaches the position command, and finally the moving body of the vibration type actuator is controlled so as to stop at a position where the output of the comparison means 13 becomes a value smaller than the predetermined deviation amount. Here, when the position of the moving body is displaced due to disturbance when it is once stopped, the comparison means 13
Until the output of is larger than the second deviation amount set to a value equal to or larger than the predetermined deviation amount,
The change in the signal PB is prohibited, and when the output of the comparison means 13 exceeds the second deviation amount, the vibration actuator is restarted. In addition, if the time until the system is restarted once it is stopped is shorter than a predetermined time, the restart may be prohibited. Further, the integral operation means 12 at the time of start-up or direction switching is stopped for a predetermined time or the number of pulses of the signal PA is counted from the start of start-up, and the operation is stopped until the predetermined count is reached, resulting in unstable vibration at start-up. If the influence of is reduced, the accuracy of position detection by the integral calculation means 12 can be improved. Further, in the present embodiment, since the vibration amplitude can be controlled at high speed, the control time in the unstable region is shortened, and the position detection accuracy of the integral calculation means 12 is further enhanced.

FIG. 4 is a timing chart showing the signal waveform of each part. With respect to the vibration amplitude displacement A0 of standing vibration excited by the piezoelectric element 1 of the vibrating body (not shown), the output of the current detection amplifier 7 of the signal I0 is a signal obtained by inverting the signal advanced by 90 °. . In addition, the current detection amplifier 7
A DC offset component is superposed on the output signal of 1) so that the inverter 8 can detect the phase of the AC signal of the output signal of the current detection amplifier 7. The signal P0 is the inverter 8
Is a pulse signal in which the phase of the output signal of the current detection amplifier 7 is inverted. The signals PA and PB are output signals of the pulse control means 4, and the signal PB is a signal delayed by T1 with respect to the signal PA, and T1 is approximately 90 °.
Is determined to correspond to the phase difference of. The signal VA is a signal obtained by amplifying the signal PA by the half bridge 5. It can be seen that the signal PA is almost synchronized with the signal P0 in the initial stage of activation. The target position is set and the PID calculation means 14
This is because even if the value corresponding to the predetermined time T1 is subtracted from the output of, the phase delay with respect to the signal P0 is 0 °. Therefore, vibration is applied with a phase advanced by approximately 90 ° with respect to the vibration displacement of the vibrating body (not shown), which increases the vibration amplitude in a short time and accelerates the operation in the shortest time. . When the target position is approached, the result of subtracting the value corresponding to the predetermined time T1 from the output of the PID calculating means 14 becomes a negative value, and the phase of the signal PA lags behind the signal P0, and the delay amount The limit is reached and finally signal P
A has a waveform obtained by almost inverting the signal P0. Also,
When the vibration amplitude becomes smaller than the second predetermined amplitude,
The signal levels of the signal PA and the signal PB are fixed so that they are not excited thereafter. This is because when the vibration amplitude becomes small, even if vibration is applied at the timing of damping the vibration, the vibration may pass through the damping and conversely increase. In this timing chart, the number of pulses of the drive voltage until acceleration, deceleration, and stop is about 10 pulses, which is a short time of the order of several 100 nSec for a vibration type actuator that is normally excited at several 10 KHz or more. Is. Due to this, the moving amount of the moving body is very small, and a very expensive one is required to detect the moving amount with a rotary encoder or the like.
In addition, there is a problem that the detection of the actual position of the moving body is delayed due to a decrease in mechanical rigidity up to the detection unit such as a rotary encoder, and the detection position vibrates.
Therefore, in this method, the speed of the moving body corresponding to the vibration amplitude of the vibrating body of the vibration type actuator is obtained in advance,
These effects are eliminated by detecting the vibration amplitude for each one cycle or half cycle of the drive voltage, converting this to speed, and integrating this speed information to determine the position. FIG. 5 shows a special drawing showing the characteristics of the speed of the moving body with respect to the vibration amplitude. It can be seen that the vibration-type actuator is stopped up to the predetermined vibration amplitude S0 (may be the third predetermined vibration amplitude), and the speed increases linearly beyond that. From this, it is understood that the velocity can be calculated from the vibration amplitude by subtracting S0 from the vibration amplitude and then multiplying by the value corresponding to the slope of this straight line.

In the above example, the oscillation amplitude is controlled by delaying the phase of PA with respect to the phase of the signal P0 of the inverter 8. However, the operation of the pulse control means in FIG. 1 is changed to advance the phase. However, the same control can be performed. This inverts the signal P0 and changes the signal edge to 18
This is realized by setting the 0 ° advance signal nP0 and controlling it in a delayed form. For example, in order to advance 30 °, the signal P0 is inverted and delayed by 150 ° with respect to the signal nP0 advanced 180 °. FIG. 6 shows a block diagram. Inverter 8
Buffer 15 is used instead of signal P0 of FIG.
The signal nP0 which is the inverted signal is output. FIG. 7 is a timing chart showing the waveform of each part in this case. In this case, when the output signal of the PID calculation means 14 at the time of start-up is positive, the phase of the signal nP0 is delayed by a value corresponding to the value obtained by adding the value corresponding to the predetermined time T1. When the vibration is increased in the shortest time, the signal edge of the signal nP0 becomes the limit. Therefore, the vibration amplitude increases in a short time and reaches the target vibration amplitude in the shortest time. When approaching the target vibration amplitude, the phase of the signal PA advances and the vibration amplitude is controlled to the target vibration amplitude. Then, when the vibration amplitude is set to 0, the delay with respect to the phase of the signal nP0 of the buffer 15 decreases, and the signal PA finally becomes a signal having the same phase as the signal nP0, and the vibration is attenuated in the shortest time. Further, as described above, when the vibration amplitude becomes smaller than the second predetermined vibration amplitude,
The signal levels of the signal PA and the signal PB are fixed so that they are not excited thereafter. FIG. 8 is a timing chart showing an operation when switching the moving direction of a moving body (not shown) driven by a vibration type actuator (not shown) by using the control circuit of the block diagram of FIG. When switching the direction, the operation of temporarily setting the vibration amplitude to 0 is performed, the signal PB is inverted after the vibration amplitude becomes smaller than the second predetermined vibration amplitude, and the vibration amplitude is controlled to the target vibration amplitude again. . Even when the direction is switched in this way, if the vibration amplitude becomes smaller than the third predetermined vibration amplitude, the integration operation of the integral calculating means 12 is substantially stopped, and the deterioration of accuracy due to the unstable vibration amplitude region is suppressed.

(Second Embodiment) FIG. 9 is a block diagram showing the configuration of the second embodiment. Reference numeral 22 denotes a rotary encoder for detecting the position of a moving body of a vibration type actuator (not shown) vibrated by the piezoelectric elements 1 and 2, and 16 denotes the first position information detected by the integral calculation means 12 and the rotary encoder 22. It is a comparison means for comparing the second position information detected in. The integral calculation means 12 is adapted to correct the integration result when the output of the comparison means 16 is a predetermined value or more. Specifically, when the absolute value of the output of the comparison means 16 becomes larger than a predetermined value, the output of the comparison means 16 is further added to the integration result of the integration calculation means 12 so that it becomes the same as the position information of the rotary encoder 22. I have to. Although the relation between the vibration amplitude and the velocity of the moving body is expressed by a simple linear expression in the first embodiment, in reality, higher-order terms are included, S0 in FIG. This is because there is a problem that the actual position is gradually deviated by a simple calculation due to variations in the value of the slope of the graph showing the relationship between the amplitude and the speed, environmental changes, and the like. Therefore, by converting the vibration amplitude to velocity and integrating it to calculate the position, it is possible to detect with a minimum time delay and enhance the position resolution, which is corrected by the information of the inexpensive low-resolution rotary encoder. A high-resolution, inexpensive position detection method has been realized.

(Embodiment 3) FIG. 10 is a block diagram showing the configuration of the third embodiment. Reference numeral 17 denotes a speed detecting means, which detects the moving speed of the moving body of the vibration type actuator (not shown) from the second position information output from the rotary encoder 22. Reference numeral 18 is a comparison means and a speed conversion means 10
The first speed information calculated from the vibration amplitude is compared with the second speed information detected by the speed detecting means 17. The speed detecting means 17 detects the speed by obtaining the reciprocal of the period of the pulse output from the rotary encoder 22, and the speed detecting means 17 detects the speed and the first speed information calculated from the vibration amplitude by the speed converting means 10 by the comparing means 18. The result of comparing the second speed information detected by the means 17 is input to the speed converting means 10. The speed conversion means 10 is the comparison means 1
The error of the speed conversion calculation is detected from the input from 8, and the value of S0 in FIG. 5 and the inclination value of the graph showing the relationship between the vibration amplitude and the speed are corrected. Specifically, AC-DC
The relationship between the vibration amplitude information from the converting means 9 and the output of the speed detecting means 17 is sequentially stored, and the regression analysis of the stored contents is periodically performed to obtain the intercept and the slope, which are used as new conversion parameters. Has become. Further, instead of suddenly changing the conversion parameter based on the calculation result, a new conversion parameter may be determined by moving average or other filter calculation using history information of the conversion parameter. Further, in the present embodiment, the output of the integral calculating means 12 is also corrected in the same manner as in the second embodiment, and the position and speed are corrected by the detection result of the rotary encoder 22, so that the position control with higher accuracy and higher resolution is performed. Is possible.

(Embodiment 4) FIG. 11 is a block diagram showing the configuration of the fourth embodiment. Reference numeral 19 denotes a CPU, which converts vibration amplitude information of a vibrating body (not shown) into first velocity information of a moving body which is moved by the vibration of the vibrating body and integrates it to obtain first position information of the moving body. The frequency of the AC voltage applied to the piezoelectric elements 1 and 2 and the phase difference between the signal PA and the signal PB are controlled based on the result of comparison between the target position and the first position information of the moving body, and finally the target position. The pulse control means 4 and the VCO 21 which will be described later are controlled so that the position of the moving body reaches. And at the same time C
When the PU 19 calculates the first speed information based on the vibration amplitude of the vibrating body based on the second speed information and the second position information of the moving body from the rotary encoder 22, It is configured to correct the conversion coefficient and the first position information. Reference numeral 20 is a D / A conversion means, which sets the input voltage of the VCO 21 based on the output data of the CPU 19. 21 is a known VCO D
A pulse signal having a frequency that is an integral multiple of the frequency of the drive voltage applied to the piezoelectric elements 1 and 2 is generated according to the output voltage of the / A conversion unit 20. Other configurations will be briefly described.
The signal PA and the signal PB output from the pulse control means 4 are 9
With the pulse signal having a phase difference of 0 °, the voltage amplitude is converted by the half bridge circuits 5 and 6, and the inductor element L
The voltage is applied to the piezoelectric elements 1 and 2 via 1 and L2. Piezoelectric elements 1 and 2 are diodes D1 and D, respectively.
2, D3 and D4 connect to the power supply voltage VDD and the GND voltage, and the applied voltage is clipped to form a trapezoidal waveform. The power supply voltage VDD is the half bridge circuits 5 and 6
A voltage higher than the power supply voltage of is set. A vibrating body (not shown) is vibrated by the piezoelectric elements 1 and 2, a progressive vibration wave is formed on the vibrating body, and a moving body in contact with this vibrating body moves. The vibration of the vibrating body is detected by the piezoelectric element 3 provided on the vibrating body, and AC-
The vibration amplitude A0 is calculated by the DC conversion means 9 and A in the CPU 19 is calculated.
It is taken into the CPU 19 by the / D conversion function. The moving body is configured to detect its moving position by the rotary encoder 22. Next CP
The operation of U19 will be described with reference to the flowcharts of FIGS. 12, 13 and 14. In FIG. 12, the vibration amplitude information is converted into speed information, and the first speed information is integrated to form first position information. Based on the result of comparison with the first position information, the driving frequency of the vibration type actuator or the signal PA, FIG. 13 and FIG. 14 show a series of operations for performing phase difference between PBs and switching between ON / OFF.
The operation | movement which correct | amends the conversion coefficient for calculating the 1st speed information by the 2nd speed information and the 2nd position information of the moving body detected by and the correction of the 1st position information is shown. Further, FIG. 15 shows a state of accelerating and decelerating to the final target position (PE) and sequentially switching the target position (PS), and FIG. 16 shows the relationship between the drive frequency and the moving speed of the vibration type actuator. It is a thing. The drive frequency of the vibration type actuator is controlled in a frequency range higher than the resonance frequency (FR), and the moving speed becomes higher as the frequency becomes closer to the resonance frequency. First, FIG. 12 will be described. The variable SG is a variable indicating the rotation direction, and in the initial state, the vibration type actuator is in a stopped state, so SG = 0 and P1 is set.
Represents the first position information, and the initial state is set to 0. Then, as the initial state, the final target position is PE
The target position PS is set to 0 and the drive frequency F is set to the initial frequency F0. Next, the vibration amplitude A0 is detected and the first speed information V1 is calculated from the vibration amplitude A0 every time the integration timing due to the timer interrupt generated every first time is generated, and V1 is a variable SG representing the rotation direction. The first position information is calculated by multiplying by P1 after setting by multiplying. To convert the vibration amplitude A0 into the first velocity information, the vibration amplitude A0 is converted to the offset constant S.
It is calculated by subtracting 0 and then multiplying by the slope constant K. Incidentally, when the vibration amplitude A0 is smaller than the offset constant S0, the integration is not performed. Next, although it is not the integration timing, the following operation is repeated at each control timing by the timer interrupt generated every second time. First, the target position PS is shown in FIG.
As shown by 5, the target position PS is sequentially updated. The target position PS is updated at each control timing until it reaches the final target position PE. Next, the stop position PD is calculated in consideration of the overrun amount at the time of stop calculated from the conversion table from the first speed information. The stop position may be calculated from the amplitude information instead of the first speed information. The overrun amount is approximately proportional to the square of the first speed information V1, and is calculated in advance or is calculated by the conversion table obtained by measurement. Next, the operation when the target position PS has not reached the final target position PE is to control the rotation direction and the drive frequency of the vibration-type actuator based on the comparison result of the target position PS and the first position information P1 based on the integration result. The first position information P1 is compared with the final target position PE, and if the first position information P1 is larger, the variable SG is set to -1 and the rotation direction of the vibration type actuator is set to CCW. Turn on drive voltage
To If the first position information P1 is smaller, the variable SG
Is set to 1 and the rotation direction of the vibration type actuator is set to CW, and the drive voltage is turned on. Next, the target position PS and the first position information P1 are compared, and if they are the same, the drive frequency is not changed, but otherwise, the drive frequency F is changed by ΔF. The changing direction is determined by the value of the variable SG, the comparison result of the target position PS and the first position information P1. For example, when the first position information P1 is smaller than the target position PS, the current rotation direction is CW, and the variable SG = 1, the rotation is delayed, so the drive frequency is lowered by ΔF to move closer to the resonance frequency. The moving speed of the body is accelerated so that the first position information P1 approaches the target position PS. Next, a case where the target position PS becomes equal to the final target position PE will be described. First, the first position information P1 and the stop position PD are compared, and if they are equal, the variable SG is set to 0, the drive voltage is turned off, and the drive frequency F is set to the initial frequency F0. Also the first
If the position information P1 of is larger than the stop position PD, SG =-
The rotation direction of the vibration type actuator is set to CCW as 1, and if it is smaller, SG = 1 and the rotation direction is set to CW. In this way, the first position information P1 is controlled to the final target position PE. Next, FIG. 13 will be described. The pulse function from the rotary encoder 22 is detected by the timer function of the CPU 19 to detect the pulse period and the number of pulses, and the second speed information V2 and the second position information P2 are detected. Next, every time the second speed information V2 and the second position information P2 are detected, the average value of the first position information P1 and the second position information P2 is calculated, and this average value is used as the first position information P1. Substituting and updating the first speed information V
A value obtained by adding a value obtained by adding 1 and the second speed information V2 to the value obtained by dividing the value by double the first speed information is multiplied by the slope constant K to be substituted into the slope constant K for updating. Further, here, the first position information P1 and the inclination constant are based on the result of simply adding the first speed information V1 and the second speed information V2 or the first position information P1 and the second position information P2. Although K is updated, each of the first and second velocity and position information may be multiplied by a coefficient and then added. Figure 1
4 shows an example of another correction method different from the correction method shown in FIG. 13, and a relationship between the vibration amplitude A0 and the second speed information V2 is stored in a data table every time the second speed information V2 is updated. The relations between the vibration amplitude A0 and the second velocity information V2 are linearly approximated by the least squares method using the data table described above each time the correction timing is reached, the offset constant S0 is determined from the offset information, and the inclination information is obtained. It is configured to determine the slope constant K. When the correction is completed, all or part of the data table is reset and the vibration amplitude A0 is again set.
The relationship between the second speed information V2 and the second speed information V2 is stored in the data table and the correction is repeated. Here, the AC
Some examples of the DC converter 9 will be described. There are several methods for detecting the information corresponding to the amplitude of the vibration detection signal output from the piezoelectric element 3. For example, a peak hold circuit detects the peak value of the vibration amplitude or rectifies and smoothes the average value. In addition to the method of detecting the value or directly detecting the amplitude information by using the effective value detecting means, for example, the vibration waveform is compared with some predetermined levels by a comparator and converted into a pulse waveform, and A method of inversely calculating the amplitude corresponding to the pulse width from the pulse width of the pulse waveform may be used. Further, in the present embodiment, while the position control of the vibration type actuator is performed, the output of the integral calculation means 12, the conversion formula of the speed conversion means 10 and the conversion data table are sequentially corrected, but once The position control operation may be performed without correction, and the offset constant S0 and the tilt constant K may be corrected according to the ratio of the first position information and the second position information. For example, the correction can be performed by multiplying the offset constant S0 and the inclination constant K by the ratio of the first position information and the second position information and substituting the first position information into the second position information. .

(Embodiment 5) In FIG. 17, 51
Is a taking lens, 52 is a quick return mirror composed of a half mirror, 53 is a sub-mirror that guides light to the autofocus detection unit, 54 is a film surface, 55 is a focusing screen, 56 is a pentaprism, and 57 is an eyepiece line-of-sight detection unit. A dichroic mirror that guides light (infrared light) from the viewfinder eyepiece, 58 is a viewfinder eyepiece lens, and 59 is a user's eye looking into the viewfinder. Reference numeral 60 denotes a pair of infrared light emitting diodes which are illumination light sources for eyepiece line-of-sight detection, and 61 an imaging lens for eyepiece line-of-sight detection, together with the finder eyepiece lens 58, image formation for eyepiece line-of-sight detection. Configure an optical system. Reference numeral 62 denotes an area sensor for detecting an eyepiece line of sight, which is substantially arranged on an image forming surface formed by the image forming lens 61, and is used for looking through a substantial viewfinder near the viewfinder eyepiece lens 58 which is an eyepiece of the observation optical system. A reflection image of the human eye 59 is captured. 63
Is an eyepiece line-of-sight detection circuit, which controls the turning on and off of the infrared light emitting diode 60 and the driving of the area sensor 62 in accordance with an instruction from the microcomputer 72, and supplies the microcomputer 72 with an image signal of the area sensor 62. 64 is a field mask for determining a plurality of distance measurement areas, and 65
Is a field lens, 66 is a secondary imaging lens having a pair for each distance measuring area, and 67 is a distance measuring image sensor having a pair of line sensors for each distance measuring area. A distance measuring circuit 68 controls driving of the distance measuring image sensor 67 according to an instruction from the microcomputer 72, and gives an image signal obtained by the distance measuring image sensor 67 to the microcomputer 72. 69 is a shutter release button, 70 is a switch (hereinafter, referred to as switch SW1) which is turned on at the first stroke which is a relatively shallow pressing amount of the shutter release button 69, 71 is a relatively deep pressing amount of the shutter release button 69. Is a release switch (hereinafter, referred to as switch SW2) that is turned on in the second stroke. That is, when the shutter release button 69 is pressed down, the switch SW1 is turned on first, and then the switch SW2 is turned on.

The microcomputer 72 is responsible for various controls of the camera. One of them is to drive the infrared light emitting diode 60 and the area sensor 62 via the eyepiece visual axis detection circuit 63, and the vicinity of the viewfinder eyepiece. Of the user's eye 59, in particular, the pupil, the Purkinje image which is a reflection image of the infrared light emitting diode 60 which is the illumination light source on the front surface of the cornea, and the like, and the positional relationship etc. Eyepiece detection that detects the presence or absence of an approaching eye, or line-of-sight detection that detects the direction in which the user is looking is performed. Other,
The image pickup sensor 67 for distance measurement is driven via the distance measurement circuit 68,
A pair of re-formed images are obtained for each distance measuring field, and the focus state of the photographing lens 51 is obtained for each distance measuring field from the correlation. Then, the line-of-sight detection information and the photographing lens 51 for each distance measuring field
Of the photographing lens 51 via the vibration type actuator control circuit 73 based on the focus state of
The line-of-sight autofocus is performed to control and move the subject to bring it into a focused state. Regarding eyepiece detection, for example, Japanese Patent Laid-Open No.
With respect to the line-of-sight autofocus in Japanese Patent No. 192338, for example, it is known in Japanese Patent Laid-Open No. 1-241511.
The detailed description is omitted because it is not the gist of the present invention. In addition, as the control of the camera, photometry, exposure control,
Shutter release control, film feeding, etc. are necessary, but these are not the subject of the present invention and will be ignored. A vibration type actuator drive circuit 73 drives a distance ring (not shown) based on a signal from the microcomputer 72 that controls the camera to change the focus state of the taking lens 1. Reference numeral 74 denotes a vibration-type actuator that drives a distance ring (not shown), and the vibration-type actuator drive circuit 73 converts vibration amplitude information of a vibration body (not shown) of the vibration-type actuator 74 into first velocity information. The first position information is obtained by integrating the first speed information, and while monitoring the first position information, the vibrating actuator 74 is driven to drive a distance ring (not shown), Change the focus state. Here, the focus state of the photographing lens 51 is a shift amount between the focus positions of the film surface 54 and the photographing lens 51, and the microcomputer 72 obtains a movement amount of a distance ring (not shown) corresponding to this shift amount. , A command for this movement amount is given to the vibration type actuator drive circuit 73. Further, the microcomputer 72 regularly monitors the focus state of the photographing lens 51 to obtain the remaining movement amount of the distance ring (not shown),
The vibration type actuator drive circuit 73 is notified of the remaining movement amount. In the vibration type actuator drive circuit 73, the remaining movement amount is used as the second position information, the second velocity information is calculated from the change in the remaining movement amount, and the first is calculated from the vibration amplitude information of the vibration type actuator 74. The method of calculating the speed information of the
Of the AC drive voltage applied to the vibration type actuator 74 based on the first position information while periodically correcting the first position information with the position information of
By controlling the phase difference between a plurality of drive voltages, a distance ring (not shown) is moved to the focal position at high speed. Further, here, the second position information is detected from the focus state, but it goes without saying that another position sensor may be used. With such a configuration, focus control of the lens can be performed without using an expensive position sensor with high resolution. Here, since the command of the movement amount and the transmission of the second position information from the microcomputer 72 to the vibration type actuator drive circuit 73 are performed by serial communication, if the position control is performed only by feeding back the second position information. ,
High-speed control cannot be performed because dead time called communication time occurs. However, according to the method of detecting the first position information and performing the position control while correcting the calculation of the first position information by the second position information, the position control can be performed at high speed with high resolution and high accuracy. Becomes Further, in the above description, the first position information is corrected by the comparison result of the second position information and the first position information. However, a method of calculating the first velocity information calculated from the vibration amplitude information of the vibration type actuator 74 will be described. You may correct it.

[0016]

As described above, according to the present invention,
By converting the vibration of the vibrating body of the vibrating actuator into velocity information and integrating this, the position of the moving body of the vibrating actuator can be detected without using an expensive position sensor.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment.

FIG. 2 is a block diagram of a vibration type actuator.

FIG. 3 is a diagram showing an electrode structure of a piezoelectric element of a vibration type actuator.

FIG. 4 is a timing chart showing waveforms of various parts of the first embodiment.

FIG. 5 is a diagram showing a relationship between vibration amplitude and velocity

FIG. 6 is a block diagram showing a modification of the first embodiment.

FIG. 7 is a timing chart showing waveforms at various parts of the embodiment of FIG. 6;

FIG. 8 is a timing chart showing another waveform of each part of the embodiment of FIG.

FIG. 9 is a block diagram showing a second embodiment example.

FIG. 10 is a block diagram showing a third embodiment example.

FIG. 11 is a block diagram showing a fourth embodiment example.

FIG. 12 is a flowchart illustrating a fourth exemplary embodiment.

FIG. 13 is a flowchart for explaining a fourth embodiment together with FIG.

FIG. 14 is a flowchart illustrating a fourth embodiment example with reference to FIG.

FIG. 15 is an explanatory diagram showing changes in the target position PS with time.

FIG. 16 is a diagram showing the relationship between the driving frequency and the speed of the vibration type actuator.

FIG. 17 is a block diagram showing a fifth embodiment example.

[Explanation of symbols]

1, 2, 3 piezoelectric elements 4 pulse control means 5, 6 Half bridge circuit 7 Current detection amplifier 8 inverter 9 AC-DC conversion means 10 Speed conversion means 11 Code switching means 12 Integral calculation means 13, 16, 18 Comparison means 14 PID calculation means 15 buffers 17 Speed detection means 19 CPU 20 D / A conversion means 21 VCO 22 Rotary encoder 51 shooting lens 52 Quick Return Mirror 53 sub mirror 54 Film side 55 Focusing Screen 56 Penta prism 57 dichroic mirror 58 finder eyepiece 59 eyes 60 infrared light emitting diode 61 Imaging lens 62 area sensor 63 Eyepiece line-of-sight detection circuit 64 visual field mask 65 field lens 66 Secondary Imaging Lens 67 Image sensor for distance measurement 68 Distance measuring circuit 69 Shutter release button 70 switch 71 Release switch 72 Microcomputer 73 Vibration type actuator drive circuit 74 Vibration type actuator

Continued front page    F-term (reference) 5H303 AA06 AA27 CC01 DD06 DD14                       FF04 GG11 GG20 JJ01 KK02                       KK03 KK04 KK10 KK17 LL03                 5H680 BB03 BB16 BC01 CC02 CC07                       DD02 DD12 DD23 DD36 DD55                       DD65 DD66 DD85 EE22 EE24                       FF24 FF30 FF38

Claims (12)

[Claims] 1. A moving position or a movement for a vibrating actuator that applies a frequency signal to an electro-mechanical energy conversion element provided on a vibrating body to obtain a driving force to perform relative movement with an object. In the quantity detecting device, a vibration detecting means for detecting a vibration amplitude of a vibrating body, a speed information converting means for obtaining speed information from amplitude information according to the detected vibration amplitude, and a position by integrating the converted speed information. Alternatively, a position detecting device for a vibration-type actuator, characterized by having an integral calculating means for detecting a displacement amount. 2. The vibration type actuator according to claim 1, wherein the conversion unit obtains velocity information by multiplying a value obtained by subtracting a predetermined value from the vibration amplitude information by a predetermined proportional constant. Position detection device. 3. A displacement amount information forming unit that is displaced by the driving force of the actuator to form information according to the displacement amount, speed information is obtained from the information from the forming unit, and the speed information is obtained based on the obtained speed information. The position detecting device for a vibration-type actuator according to claim 2, wherein the proportional constant is corrected. 4. Displacement amount information forming means for forming information according to the amount of displacement, which is displaced by the driving force of the actuator, is provided, and the output of the integral computing means is corrected by the information from the forming means. The position detecting device for a vibration-type actuator according to claim 1, 2, or 3. 5. When the difference between the information from the displacement amount information forming means and the information according to the displacement amount detected by the integral calculating means is a predetermined value or more, the output of the calculating means is converted into the information from the forming means. The position detecting device for a vibration type actuator according to claim 4, wherein the position detecting device is changed. 6. A displacement amount information forming unit that is displaced by the driving force of the actuator to form information according to the displacement amount, speed information is obtained from the information from the forming unit, and the speed information is obtained based on the obtained speed information. The position detecting device for the vibration type actuator according to claim 1, wherein the speed information of the speed information converting means is corrected. 7. The integral operation means does not perform integration at the time of starting or reversing the vibration type actuator for a predetermined time or a predetermined number of drive pulses or until a predetermined vibration amplitude is reached. The position detecting device for the vibration type actuator according to claim 1, 2 or 3 or 4 or 5 or 6. 8. When reversing the vibration type actuator, the drive voltage is switched so as to be reversed by the vibration type actuator after the vibration amplitude becomes smaller than a predetermined amplitude. Alternatively, the position detecting device of the vibration type actuator according to 4 or 5 or 6 or 7. 9. A moving position or a movement for a vibration type actuator that applies a frequency signal to an electro-mechanical energy conversion element provided on a vibrating body to obtain a driving force to perform relative movement with an object. In the quantity control device, a vibration detecting means for detecting the vibration amplitude of the vibrating body, a speed information converting means for obtaining speed information from amplitude information according to the detected vibration amplitude, and a position by integrating the converted speed information. Alternatively, it is characterized by comprising an integral calculation means for detecting a displacement amount, a comparison means for comparing the integration result of the integral calculation means with a desired target position, and a control means for controlling the vibration type actuator based on the comparison result. Position control device for vibration type actuator. 10. The moving amount at the time of the stop operation is calculated based on the vibration amplitude immediately before the stop or the speed information obtained from the converting means, and the stopping operation is started from before the target position by the moving amount. The position control device for a vibration-type actuator according to claim 9. 11. In a photographing apparatus having a lens for performing focus control using a vibrating actuator composed of a vibrating body and a moving body in contact with the vibrating body, a vibration detecting means for detecting the vibration of the vibrating type actuator and the speed of the vibration. Conversion means for converting into information, integral calculation means for detecting the position by integrating the converted speed information, comparison means for comparing the integration result with a desired target position, and controlling the vibration type actuator based on the comparison result. Imaging comprising control means, position detection means for directly or indirectly detecting the position of the lens for focus control, and correction means for correcting the integration result according to the position of the lens and the integration result apparatus. 12. The photographing apparatus according to claim 11, wherein the detecting means detects a value corresponding to a positional shift between the image forming position of the object to be photographed and the recording member or the image pickup section.