JPH11215866A - Controller of vibrating motor, and driver using vibrating motor as driving source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the controller of a vibrating motor which can control the vibrating motor accurately by phase difference control system, by removing the erroneous detection of a phase difference. SOLUTION: This controller is so constituted as to control an alternating signal, according to a phase difference, with its control target on a vibrating motor which is driven with roughly the same phase with respect to the phase difference between the alternating signal to be applied to the piezoelectric element for drive of phase difference detection system of the vibrating motor and the detection signal outputted from a piezoelectric element for detection of the vibrating state of the vibrator. In this case, this control is composed of a comparator 9 which generates rectangular waves from the drive signal, a comparator 10 which generates rectangular waves from the above detection signal, a phase difference detector 12 which detects the phase difference from the outputs of both comparators 9 and 10, and an inverter 11 which inverts either of the outputs of both comparators 9 and 10 and inputs it into the phase detector 12.

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 a vibration type motor and a drive device using the vibration type motor as a drive source.

[0002]

2. Description of the Related Art Conventionally, as a control device for a vibration-type motor such as a vibration-wave motor, for example, as shown in Japanese Patent Application Laid-Open No. 6-1565, a plurality of vibration components constituting a vibration type motor, for example, One of the two drive signals applied to the piezoelectric element as the driving electro-mechanical energy conversion element, which is displaced from the other, and one of the driving signals as a vibration detection electro-mechanical energy conversion element provided on the vibrating body. A drive control based on a phase difference of an output signal from a vibration detecting piezoelectric element has been proposed.

The phase control detects a phase difference between a driving signal to a driving electro-mechanical energy conversion element and an output signal from a vibration detecting electro-mechanical energy conversion element, and obtains information on the obtained phase difference. This is a frequency control method.

[0004] As characteristics of the rotational frequency of the vibration wave motor, the drive frequency, and the phase difference, when the frequency is gradually lowered from the frequency higher than the resonance frequency of the vibrating body, and the speed gradually increases after the motor starts rotating, The phase difference also gradually approaches the resonance state (when the vibration detecting piezoelectric element and the driving piezoelectric element used for detecting the phase difference are arranged in the same phase). When the phase is in a resonance state, the rotation speed of the motor reaches near the highest speed. When the frequency is further reduced from the resonance state, the rotation speed rapidly decreases, and the phase also deviates from the resonance state. Therefore, in order to prevent the phase from proceeding from the resonance state to a lower frequency, when the phase is detected and approaching the resonance state, control is performed to return the frequency to a higher frequency.

The relationship between the frequency and the frequency of the vibration wave motor and the phase difference is substantially as shown in FIG. In the phase control, for example, phases θ1 and θ2 are set, and when the detected phase difference is smaller than θ2, the speed is increased by lowering the frequency. If the detected phase difference exceeds θ2, it is determined that resonance has been approached, and control is performed so as to decrease the speed by increasing the frequency.

[0006]

However, in the conventional example described above, due to the characteristics of the vibration wave motor, the driving signal to the driving electro-mechanical energy conversion element and the output signal from the vibration detection electro-mechanical energy conversion element are considered. When the detection signal is blurred due to noise or uneven rotation, the driving signal to the driving electro-mechanical energy conversion element and the vibration detection -The phase difference of the output signal from the mechanical energy conversion element is inverted, and it is judged that the phase has approached the resonance state, and the frequency is returned to the higher side.Therefore, the speed cannot be increased from the drive speed at startup. Can be considered.

An object of a first invention according to the present application is to solve the problem of the phase difference control method, eliminate the erroneous detection of the phase difference, and accurately control the vibration wave motor by the phase difference control method. It is intended to provide a control device.

An object of a second invention according to the present application is to provide a driving apparatus using a vibration type motor capable of accurately driving a driven body by a vibration wave motor driven and controlled by a phase difference control method. Is what you do.

[0009]

A first configuration for realizing the first invention according to the present application is that one of a plurality of alternating signals applied to an electro-mechanical energy conversion element for driving a vibrating body is used. The phase difference of the detection signal output from the vibration-state detection electro-mechanical energy conversion element of the vibrating body is a vibration type motor that starts in substantially the same phase as the control target, and the plurality of alternating signals according to the phase difference. A control device for controlling a vibration-type motor, wherein the first comparison means generates a signal for detecting a phase difference from a drive signal provided for the phase difference detection, and a phase difference is detected from the detection signal. Second comparing means for generating a signal, a phase difference detecting means for detecting a phase difference from the outputs of the first comparing means and the second comparing means, the first comparing means and the second comparing means. Any of the outputs of the comparison means Inverted one, and has a reversing means for inputting to the phase difference detecting means.

According to the above-described configuration, due to the characteristics of the vibration type motor, in the vibration type motor which starts up with the phase difference between the drive signal and the detection signal being substantially the same, blurring of the detection signal due to noise or uneven rotation occurs. Even if the phase difference is not inverted, accurate phase control driving can be performed.

A second configuration for realizing the object of the first invention according to the present application is one of a plurality of alternating signals applied to an electro-mechanical energy conversion element for driving a vibrating body,
A vibration type motor that starts in substantially the same phase as a detection signal output from the vibration-state detection electro-mechanical energy conversion element of the vibrating body is set as a control target, and the plurality of alternating signals are controlled according to the phase difference. A vibration type motor control device that generates a signal for detecting a phase difference from a drive signal provided for the phase difference detection;
Second comparing means for generating a signal for detecting a phase difference from the detection signal; phase difference detecting means for detecting a phase difference from outputs of the first comparing means and the second comparing means; And a reversing means for reversing one of the drive signal and the detection signal for the first comparing means and the second comparing means.

In the above-described second configuration, similarly to the above-described first configuration, due to the characteristics of the vibration type motor, in the vibration type motor that starts up with the phase difference between the drive signal and the detection signal being substantially the same, noise is reduced. Alternatively, even if the detection signal is blurred due to rotation unevenness or the like, the inversion of the phase difference does not occur, and accurate phase control driving becomes possible.

According to a second aspect of the present invention, there is provided a driving apparatus using a vibration motor as a driving source, the driving apparatus including the vibration motor driving apparatus according to any one of the above-described structures. A driven body is driven by using the vibration type motor as a drive source.

[0014]

FIG. 1 shows a first embodiment of the present invention.

The embodiment shown in FIG. 1 uses a vibration wave motor as a vibration type motor as a driving source of a photographing lens. A lens CPU 1 disposed on a lens barrel side is disposed on a camera body side. The lens CPU 1 and the camera CPU 19 communicate with each other through the contact 18 through the contact 18, and stop the drive of the focus motor and the aperture from the camera, request transmission of lens data, and the like. Lens CPU1 is camera CPU1
9 is performed in accordance with the instruction.

When the lens CPU 1 receives the focus motor driving command from the camera CPU 19, the D / A converter 2 drives the vibration wave motor 13 as a focus motor at a predetermined frequency so that a predetermined frequency can be obtained. Transmit predetermined data.

The D / A converter 2 outputs a voltage value corresponding to the digital data from the lens CPU 1 to a voltage-frequency converter (hereinafter abbreviated as VCO) 3 for converting the voltage value into a frequency signal. The VCO 3 sends a signal of a frequency corresponding to the input voltage value to the frequency divider / phase shifter 4. The dividing / phase shifter 4 has a VCO 3
From the frequency signal from the controller, a rectangular wave having a phase difference of two 90 degrees or 270 degrees, that is, an A-phase output (AOUT) and a B-phase output (BOUT) is output.

The rotation direction signal DIR sent from the lens CPU 1 to the frequency divider / phase shifter 4 determines the rotational direction of the vibration wave motor, and outputs AOUT and BOUT from the frequency divider / phase shifter 4 in accordance with this signal. Is changed between 90 degrees and 270 degrees.

Further, a frequency divider / phase shifter 4 is provided from the lens CPU 1.
The USM ON / OFF signal sent to the ON / OFF switch turns the vibration wave motor 13 ON and OFF. In response to this signal, the frequency divider / phase shifter 4 turns ON / OFF the output of the AOUT and BOUT signals.
It operates to perform FF.

The rectangular wave AO output from the frequency divider / phaser 4
The power amplifiers 5 and 6 amplify the UT and BOUT to voltages and currents that can drive the vibration wave motor 13. The AOUT and BOUT signals amplified by the power amplifiers 5 and 6 respectively pass through the matching coils 7 and 8 and pass through the vibration wave motor 13.
Is supplied as a so-called A-phase and B-phase drive signal.

When the A-phase and B-phase drive signals are supplied to the vibration wave motor 13, the vibration wave motor 13 rotates in a direction corresponding to the A-phase and B-phase. When the motor rotates, the pulse plate 15 rotates, and a signal corresponding to the rotation is output by the photo interrupter 16, amplified and shaped by the detection circuit 17, and sent to the lens CPU 1. The lens CPU 1 counts this pulse, determines whether or not the driving amount sent from the camera CPU 19 has been reached, and controls the driving and stopping of the vibration wave motor 13.

The A-phase, which is one of the drive signals for driving the vibration wave motor 13, is sent to the first comparator 9 for waveform shaping for use in phase control. Further, the vibration wave motor 13 is provided with a vibration detection element, and a detection signal (hereinafter abbreviated as S phase) is also sent to the second comparator 10 for waveform shaping to be used for phase control.

One input terminal of each of the first and second comparators 9 and 10 is connected to a certain reference voltage, and compares this reference voltage with A-phase and S-phase signals and outputs a rectangular wave.

The output of one of the outputs of the second and second comparators (the second comparator in the present embodiment) is inverted by the inverter 11 and then input to the phase detector 12.

The phase detector 12 has an output of the first comparator 9 and an inverter 11 which is an inverted signal of the second comparator 10.
, The number of clocks from the rise of the signal of the first comparator 9 to the rise of the signal of the inverter 11 is counted, and the count value is sent to the lens CPU 1.

The lens CPU 1 detects the phase difference between the A phase and the S phase from the output of the phase detector 12. According to the detected phase difference, the data to the D / A converter is changed, and the frequency of the drive signal for driving the vibration wave motor 13 is changed for control.

Depending on the characteristics of the vibration wave motor 13, FIG.
As shown in (a), when the motor is started, the amplitude of the S-phase signal may not be sufficiently obtained, and an accurate phase difference may not be detected. As a measure against this, for example, FIG.
The signal of the A phase is slightly superimposed on the S phase by the capacitor 14 shown in FIG. When the A-phase signal is superimposed on the S-phase, a signal as shown in FIG. 3B is obtained, and the phase difference can be correctly detected. In this case, A
The phase and the S phase are almost the same. The driving piezoelectric element to which the A-phase signal is applied and the piezoelectric element for detecting the vibration state are arranged in the same phase.

The relationship between the A phase and the S phase of the vibration wave motor 13 is, for example, as shown in FIG. 3C, when the speed increases after the start, the S phase gradually delays from the A phase. Works as follows. If the delay of the S phase exceeds a certain phase difference, the number of revolutions of the vibration wave motor 13 sharply decreases. Therefore, control is performed so that the A phase and the S phase do not exceed a predetermined phase difference.

The phase detector 12 is configured, for example, as shown in FIG. FIG. 4 shows waveforms of main parts in FIG.

In FIG. 2, when the output AIN of the first comparator 9 is input to the clock terminal of the D latch 201, AIN
Output of the D latch 201 at the rising edge of “H”
Becomes Since this signal is supplied as an enable signal of the counter 205, the counter 205 starts counting.

When -SIN, which is an inverted signal of the second comparator 10, is input to the D latch 202, the NAND gate 203 becomes "L" for a predetermined period when -SIN rises.
The output of the latch 201 is set to “L”. When the output of the D latch 201 becomes “L”, the enable terminal of the counter 205 becomes “L”, and the counter 205 stops counting. When -SIN falls, the OR gate 20
4 becomes "L" for a predetermined period, and the counter 205 is cleared. The lens CPU 1 reads data while the counter holds the counter value, or provides a circuit for storing the previous counter value until a new count value is determined. By taking in the value, the lens CPU can detect the phase difference between the A phase and the S phase.

Next, the lens CPU 1 will be described with reference to FIGS.
Is the vibration wave motor 13 when the phase difference between the A phase and the S phase is detected.
The processing of the driving frequency to the drive will be described.

When the vibration wave motor is driven in step # 601 of FIG. 6, the lens CPU 1 starts detecting the phase difference between the A phase and the S phase.

In step # 602, it is determined whether or not the phase difference is equal to or smaller than θ2. If the phase difference is equal to or smaller than θ2, the process proceeds to step # 603, in which the driving frequency of the vibration wave motor is reduced, and the rotation speed of the motor is stopped. The state where the phase difference is equal to or smaller than θ2 is the state shown in FIG.

If the phase difference is not smaller than θ2 in # 602, it is determined in # 604 whether the phase difference is smaller than θ1.

If the phase difference is equal to or smaller than θ1 in # 604,
Proceeding to step # 605, the drive frequency is maintained as it is. # 60
The fact that the phase difference is equal to or smaller than θ1 at 4 indicates that the phase difference is larger than θ2 and equal to or smaller than θ1 as shown in FIG.

If the phase difference is not equal to or smaller than θ1 in step # 604, a process for increasing the drive frequency and reducing the drive speed of the vibration wave motor is performed in step # 606. The fact that the phase difference is not less than θ1 in # 604 indicates that the phase difference exceeds θ1 as shown in FIG. 5C.

According to the above processing, control is performed such that the phase difference between the A phase and the S phase is between θ2 and θ1.

Before describing the features of the present embodiment, the operation in the conventional processing will be described. Conventional processing corresponds to the case where there is no inverting circuit 11 in FIG.
Here, a driving piezoelectric element for applying a drive signal for phase detection and a piezoelectric element for detecting vibration, which are disposed on a vibrating body of the vibration wave motor, and a driving signal are applied to the driving piezoelectric element. Assuming that the wavelength of the standing wave formed by this is λ, the standing wave is disposed at a position of an integral multiple of the wavelength λ. Therefore, when the driving piezoelectric element is driven by the A-phase driving signal at the time of startup, the vibration generated by this driving and propagating through the vibrating body reaches the vibration detecting piezoelectric element and outputs a detection signal.

In FIG. 7, when the vibration wave motor starts, the A-phase and the S-phase start to be almost in phase. However, during normal operation, the A phase does not always lag the S phase.
(A), the lens CPU 1 controls the driving frequency of the motor, so the time T is known, and the SIN starts from the rise of AIN ('-' is not attached because it is not inverted). By inputting the count value of the number of clocks for which the frequency up to the rising edge is known, the time t can be determined, and the phase difference x degrees can be obtained from 360 degrees: x degrees = T: t. As a result, immediately after the start, the driving frequency is reduced as much as possible in the direction of increasing the speed because the phase difference is equal to or less than θ2.

However, as shown in FIG. 7 (b), the phase relationship between the A phase and the S phase may be reversed due to noise, uneven rotation of the vibration wave motor, waveform distortion due to the rotational twist of the vibrator, or the like. I do.

When the phase difference between the A phase and the S phase is reversed,
Since the phase difference is detected from the rising of AIN to the rising of SIN, the detected phase difference becomes larger than θ1, as shown in FIG. 7B. If it is determined that the phase difference is larger than θ1, the drive frequency is changed in the direction of decreasing the speed, so that the speed does not increase even immediately after the start, and the vibration wave motor rotates slowly.

On the other hand, in this embodiment, as shown in FIG. 1, since the inverter 11 is provided, the phase is detected as shown in FIG.

FIG. 8A shows a case where the phase at the start is output without being inverted. The output of the S-phase comparator is inverted, and the values of the phases θ2 and θ1 set accordingly shift. (Half the wavelength of the conventional case).

Noise or uneven rotation of the vibration wave motor,
FIG. 8 shows waveform distortion due to rotational torsion of the vibrating body.
As shown in (b), even if the phase relationship between the A-phase and the S-phase is reversed, it is not determined that the detected phase difference exceeds θ1, so that the processing is correctly performed to increase the speed. Become.

That is, in the normal case shown in FIG. 8A, the actual phase difference t is added to T / 2, and in the abnormal case shown in FIG. Since the value is smaller than T / 2, the phase difference detector 12 outputs detection information corresponding to the actual phase difference state.

The phase detector 12 is configured to send the count value of the clock to the lens CPU 1. For example, counter values corresponding to θ2 and θ1 are set, and when the respective phases are exceeded, “H” is set. Otherwise, a circuit is set to "L", and the resulting data is stored in the lens CPU 1
May be configured to be input.

The first and second comparators 9 and 10 or
The output of the inverter 11 may be directly input to the lens CPU 1 so that the lens CPU 1 performs the subsequent phase detection processing.

According to the present embodiment, the vibration wave motor A
By inverting one of the outputs to the first and second comparators for detecting the phase difference between the phase and the S phase and supplying the inverted output to the phase difference detector, the A phase and the S phase are substantially different due to the characteristics of the motor. In the case of starting in the same phase, even if the phase difference is reversed, normal motor control can be performed without the problem that the speed does not decrease.

(Second Embodiment) FIG. 9 shows a second embodiment of the present invention.
An embodiment will be described.

FIG. 2 differs from FIG. 1 in that an inverting amplifier 20 for inverting an S-phase signal is provided instead of the inverter 11 in FIG. FIG. 10 shows waveforms indicating the operation of FIG.

As shown in FIGS. 10A and 10B, in this embodiment, the phase difference detected by the phase detector 12 is abnormal, as shown in FIG. FIG. 8B showing the case is the same as in the first embodiment.
In FIGS. 10A and 10B, the S-phase waveform shown by the dotted line is inverted as shown by the solid line, which is different from FIGS. 8A and 8B in the first embodiment. However, even if the phase difference is inverted due to noise at startup, uneven rotation of the vibration wave motor, waveform distortion due to rotation of the vibrator, or the like, the vibration wave motor can be controlled normally.

[0053]

According to the first aspect of the present invention, the phase difference between the A-phase and the S-phase is reversed after the start-up due to noise, uneven rotation of the vibration type motor, waveform distortion due to the rotation torsion of the vibration body, and the like. However, there is an effect that the phase control of the vibration wave motor is correctly performed, and desired vibration type motor control is realized.

According to the second aspect of the present invention, a driven body such as a photographing lens can be accurately driven by a vibration motor.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram of the phase detector of FIG. 1;

FIGS. 3A and 3B show waveform diagrams of an A phase and an S phase, and FIG.
(B) shows the case where the A-phase signal is superimposed on the S-phase, and (c) shows the case where the speed is increased after starting.

FIG. 4 is a waveform diagram of a main part of FIG. 2;

5A and 5B show a phase relationship between an A phase and an S phase. FIG. 5A shows a case where the phase difference is equal to or less than θ ₂ , FIG. 5B shows a case where the phase difference is between θ ₁ and θ _2, and FIG. If the phase difference exceeds the θ _1.

FIG. 6 is a flowchart illustrating a flow of phase control according to the first embodiment;

FIG. 7 is a waveform diagram showing an example of conventional phase detection of A and S phases.

FIG. 8 is a waveform chart showing an example of phase detection of A phase and S phase in FIG. 1;

FIG. 9 is a block diagram of a second embodiment of the present invention.

FIG. 10 is a diagram illustrating an example of phase detection of the A phase and the S phase in FIG. 9;

FIG. 11 is a diagram illustrating frequency characteristics of the phase and the number of rotations of the vibration wave motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens CPU 2 D / A converter 3 Voltage-frequency converter (VCO) 4 Divider / Phase converter 5, 6 Power amplifier 7, 8 Matching coil 9 First comparison circuit 10 Second comparison circuit 11 Inverter 12 Phase Detection circuit 13 Vibration wave motor 18 Contact 18 Camera CPU 20 Inverting amplifier

Claims (7)

[Claims] 1. One of a plurality of alternating signals applied to an electro-mechanical energy conversion element for driving a vibrating body,
A vibration type motor that starts in substantially the same phase as a detection signal output from the vibration state detecting electro-mechanical energy conversion element of the vibrating body is set as a control target, and the plurality of alternating signals are controlled according to the phase difference. A vibration type motor control device, comprising: first comparing means for generating a signal for detecting a phase difference from a drive signal provided for the phase difference detection; and a detecting means for detecting a phase difference from the detection signal. A second comparing means for generating a signal; a phase difference detecting means for detecting a phase difference from outputs of the first comparing means and the second comparing means; a first comparing means; A control device for a vibration-type motor, comprising: inverting means for inverting one of the outputs of the comparing means and inputting the inverted signal to the phase difference detecting means. 2. An alternating signal of a plurality of phases applied to an electro-mechanical energy conversion element for driving a vibrating body,
A vibration type motor that starts in substantially the same phase as a detection signal output from the vibration-state detection electro-mechanical energy conversion element of the vibrating body is set as a control target, and the plurality of alternating signals are controlled according to the phase difference. A vibration type motor control device, comprising: first comparing means for generating a signal for detecting a phase difference from a drive signal provided for the phase difference detection; and a detecting means for detecting a phase difference from the detection signal. A second comparing means for generating a signal; a phase difference detecting means for detecting a phase difference from outputs of the first comparing means and the second comparing means; a first comparing means and the second comparing means; A control device for a vibration-type motor, comprising: inverting means for inverting one of the drive signal and the detection signal for a comparing means. 3. A driving device according to claim 1, further comprising a determination unit configured to determine whether the driving state is good or bad based on a threshold value set between a half period and one period of the driving signal based on the phase difference signal detected by the phase difference detection unit. The control device for a vibration-type motor according to claim 1. 4. The determination means inputs detection information detected by the phase difference detection means as a pulse count value,
The control device for a vibration-type motor according to claim 3, wherein the quality of the driving state is determined. 5. The method according to claim 1, wherein a drive signal used for detecting the phase difference is superimposed on the detection signal.
5. The control device for a vibration type motor according to 2, 3, or 4. 6. A vibration-type motor, comprising: the vibration-type motor drive device according to claim 1, wherein the vibration-type motor drives a driven body using the vibration-type motor as a drive source. A driving device that uses as a driving source. 7. A driving apparatus using a vibration type motor as a driving source, wherein the driven body is a photographing lens.