JPH06197561A - Vibration-wave motor driving circuit - Google Patents

Abstract

PURPOSE:To provide a vibration-wave motor which can be controlled with a low-function microcomputer and, in addition, the control software of which can be more simplified than the conventional example. CONSTITUTION:When this circuit provided with a second oscillator control means 17 in addition to a first oscillator control means 2 and, at the same time, a numerical value comparator circuit (selecting means) 3 that selects an output yielding a high frequency out of the outputs of the control means 2 and 17 and inputs the selected output to a variable-frequency oscillator 5 through an A/D converter 4 in the prestage of the oscillator 5 is used, no high- function microcomputer 1 is required, since the microcomputer 1 is not required to always monitor the phase difference between driving signals and vibration detecting signals. In addition, since the software of the circuit can be simplified, the controlling method of the circuit becomes simple and the cost of the circuit can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration wave motor drive circuit for controlling the drive of a vibration wave motor.

[0002]

2. Description of the Related Art A conventional oscillatory wave motor drive circuit is shown in FIG. 101 is a microcomputer for controlling the drive of the vibration wave motor, and 102 is the microcomputer 10.
8-bit UP / DOWN counter whose count value changes according to the UP / DOWN signal output from 1
3 is a D / A converter for converting the digital signal of the count value output from the UP / DOWN counter 102 into an analog signal, and 104 is a variable frequency oscillator (VC) whose oscillation frequency is controlled by the output voltage from the D / A converter.
O), 105 is a vibration wave motor driving logic for generating an output signal of the variable frequency oscillator (VCO) 104 and two signals having the same frequency but different phases for driving the vibration wave motor, and 106 drives the vibration wave motor. High-voltage power supply for driving, 107 and 108 are power amplifiers for driving the vibration wave motor, 109 and 110 are matching coils for driving the vibration wave motor, 111 is the body of the vibration wave motor, and 112 is the vibration wave motor 111. A comparator that receives one of the two signals applied to
Is a comparator that receives the output signal of a sensor that detects the vibration of the oscillator of the vibration wave motor 111, and 114 is a phase comparison circuit that detects the phase difference between the output signals of the comparators 112 and 113.

Next, the operation of the above circuit will be described.
The relationship between the drive frequency and the rotation speed of the vibration wave motor has the characteristics shown in FIG. 4. Normally, the drive frequency is scanned from the higher side to the lower side and the frequency is reached at the rotation speed between N1 and N2. To stop the scan and drive the vibration wave motor.

If the frequency is scanned further downward from here, the rotation speed becomes maximum, but if the frequency is further lowered, the rotation speed suddenly drops. Further, the relationship of the phase difference between one of the signals applied to the vibration wave motor and the output of the sensor for detecting the vibration state of the vibration wave motor is as shown in FIG. In order to drive the vibration wave motor, the value of the phase detected by the phase detection means is 90 ° in the vibration wave motor shown in the conventional example.
It must be controlled to be ~ 110 °.

In order to rotate the vibration wave motor in this way, the microcomputer 101 uses the signal line 121 to U
The P signal, the DOWN signal and a reset signal (not shown) are output from the signal line 122 to the UP / DOWN counter 102, and the count value of the UP / DOWN counter 102 is set to 0.
0h. As a result, the output of the UP / DOWN counter is input to the D / A converter 103 through the signal line 123, the output of the D / A converter 103 at this time is minimized, and this output is the variable frequency oscillator (VCO) 104.
VCO 104 oscillates at the highest frequency.

This oscillation signal is input to the oscillatory wave motor drive logic 105, which has the same frequency and a phase of 9
A vibration wave motor drive signal that differs by 0 degrees is generated. This signal is supplied to the power amplifiers 107 and 1 powered by the high voltage power supply 106.
08 is amplified to electric power required to drive the vibration wave motor, and is applied to the two piezoelectric element groups of the vibration wave motor 111 via the matching coils 109 and 110. At this time, the frequency of the signal applied to the piezoelectric element is UP
Since the count value of the / DOWN counter is 00h, the vibration wave motor has a rotation speed of 0 and does not rotate as shown in FIG.

At this time, the phase difference detected by the phase comparison circuit 114 has a value close to 360 degrees as shown in FIG. 4B, so that the vibration wave motor can be driven accurately. Must lower the drive frequency.

Next, the microcomputer 101 outputs the UP signal to the UP / DOWN counter through the signal line 121 to set the count value of the UP / DOWN counter 102 to 0.
The output voltage of the D / A converter 103 is slightly increased by changing from 0h to 01h, and the oscillation frequency of the variable frequency oscillator (VCO) 104 is slightly decreased. By repeating this, the driving frequency of the vibration wave motor becomes low, so that the vibration wave motor starts to rotate and the rotation speed becomes high.

When the drive frequency is further lowered, the vibration wave motor sharply lowers its rotation speed. In order to prevent this, the phase difference between one of the drive signals applied to the vibration wave motor and the signal output from the sensor of the vibration wave motor is detected by the phase comparison circuit 114, and the result of this phase difference detection is sent through the signal line 127. It is input to the microcomputer 101, and the microcomputer 101 constantly monitors the phase difference signal and outputs a U to the UP / DOWN counter 102.
The drive frequency of the vibration wave motor is controlled by outputting the P signal or the DOWN signal. As a result, the drive frequency of the vibration wave motor has a phase difference of 90 ° to 110 ° as shown in FIG.
Controlled to be °. When controlling the rotation speed of the vibration wave motor, a speed detection unit for the vibration wave motor is further provided, and the vibration wave motor is controlled using the speed detection result and the phase difference.

[0010]

However, the phase difference detected in the above conventional example is constantly changing due to fluctuations in the power supply voltage, fluctuations in the load driven by the vibration wave motor, fluctuations in temperature, etc. Must always monitor the phase difference between the drive signal of the vibration wave motor and the sensor output of the vibration wave motor. Further, when the speed control and the like are also performed, it is necessary to monitor the speed and the above-mentioned phase difference at all times to appropriately control the vibration wave motor. For this reason, the control software of the microcomputer becomes complicated, a high-performance microcomputer is required as compared with the case of controlling the drive of a DC motor, and other actuators cannot be controlled at the same time. There are drawbacks.

Accordingly, it is an object of the present invention to provide an improved vibration wave motor drive circuit which does not have the drawbacks inherent in the conventional vibration wave motor drive circuits as described above, and more particularly to the prior art. The drive control of the vibration wave motor can be performed by a simpler control method than that of the drive circuit of, and the microcomputer with a low cost can be obtained without the high-performance microcomputer required in the conventional drive circuit. An object of the present invention is to provide a controllable vibration wave motor drive circuit.

[0012]

An oscillatory wave motor drive circuit according to the present invention comprises first and second variable frequency oscillator control means for controlling the variable frequency oscillator described above, and the first and second variable frequency oscillators. Selecting means for selecting an output representing a high frequency from the respective outputs of the control means to drive the variable frequency oscillator, the first variable frequency oscillator control means comprising: The variable frequency oscillator according to the phase difference between the phase of the AC signal for vibration and the phase of the output signal of the vibration state detection sensor, and the second variable frequency oscillator control means detects the speed of the vibration wave motor. It is configured to control the variable frequency oscillator according to the value.

[0013]

In the oscillatory wave motor drive circuit according to the present invention, the selecting means automatically selects the output representing the higher frequency from the outputs of the first and second variable frequency oscillator control means, and the variable frequency. Since it is input to the oscillator, the vibration wave motor can be properly controlled even if the microcomputer does not always monitor the above-mentioned phase difference detection result, and it is not necessary to use a high-performance microcomputer as well as the vibration wave motor. Can be controlled by the same simple control method as the control of the DC motor.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a diagram showing a specific example of the drive circuit for the vibration wave motor of this embodiment. First, the configuration of each part will be described.

Reference numeral 1 denotes a microcomputer, which controls the operation sequence of each circuit element described below. 2 is an 8-bit UP / DOWN counter whose count value changes according to the UP / DOWN signal from the microcomputer 1. 3 is a numerical value comparison circuit which compares two input values and outputs the larger value. 4 is an input. A / D converter whose output voltage changes according to a numerical value, 5 is a variable frequency oscillator whose oscillation frequency changes according to the input voltage, and 6 is necessary for driving the vibration wave motor from the input AC signal.
Oscillation wave motor control logic for producing two signals of the same frequency different in phase by 0 degree, 7 is a high voltage power supply for driving the oscillation wave motor, 8 and 9 are power amplifiers for driving the oscillation wave motor, 10 And 11 are matching coils for driving the vibration wave motor, 12 is a vibration wave motor, 1
Reference numerals 3 and 14 are converters, 15 is a phase difference detection circuit for detecting a phase difference between two input signals, and 16 is a phase difference obtained by comparing the set phase value and the input phase value at regular time intervals. A phase comparator circuit for outputting an UP / DOWN signal in response to the 8-bit UP / DOWN counter, the count value of which changes according to the input UP / DOWN signal.
Reference numeral 18 is a speed detecting means for detecting the rotation speed.

The operation of the vibration wave motor drive circuit of this example having the above-described circuit configuration will be specifically described below.

When a signal for driving the vibration wave motor is given to the microcomputer 1 by means (not shown), the UP / DOWN counter 2 and the UP / DOWN counter 2 are made through signal lines (not shown).
Reset the DOWN counter 17 and set the count value to 00.
In addition to h, a signal line (not shown) gives a signal for driving the vibration wave motor and the rotation direction of the vibration wave motor to the vibration wave motor driving logic 6.

At this time, the limit value of the phase difference between the signal applied to the vibration wave motor for properly controlling the vibration wave motor and the signal generated in the sensor (the value of the phase difference at this time is 9
0 °) is output to the phase comparison circuit 16 through the signal line 29. As a result, the UP / DOWN counter 2 and U
The count value of the P / DOWN counter 17 becomes 00h, and the numerical value comparison circuit 3 includes the signal line 23 and the signal line 3 respectively.
Since 00h is input through 2, the output of the circuit 3 is 0
It becomes 0h, and this value 00h is A / D through the signal line 24.
It is input to the converter 4.

At this time, the output of the A / D converter 4 becomes the smallest, and therefore the frequency of the signal generated by the variable frequency oscillator 5 becomes the highest. This oscillating signal is input to the vibration wave motor drive logic 6 to be frequency-divided, and at the same frequency necessary for driving the vibration wave motor, a phase difference 9
It is converted into two vibration wave motor drive signals that differ by 0 °.
These two vibration wave motor drive signals are input to power amplification circuits 8 and 9 using the high-voltage power supply 7 as a power source and amplified to the power required to drive the vibration wave motor, and the matching coil 1
It is applied to the vibration wave motor 12 through 0 and 11.

At this time, the drive frequency applied to the vibration wave motor 12 is 00h when the value input to the A / D converter 4 is 00h.
Therefore, the maximum frequency is reached as shown in FIG. 4A, and the vibration wave motor 12 does not rotate at this time, so the speed detected by the speed detection means 18 of the vibration wave motor is zero. Further, the phase difference between the drive signal applied to the vibration wave motor 12 and the output signal of the sensor of the vibration wave motor 12 is a value close to 360 °. To detect this phase difference, the signals converted into digital signals by the comparators 13 and 14 are input to the phase difference detection circuit 15, and the signal line 28
Is output through. Now, the phase setting value 90 ° is input to the phase difference comparison circuit 16 through the signal line 29.
Since the actual phase detection value is larger than this, the phase comparison circuit 1
6 outputs the UP signal to the UP / DOWN counter 17 through the signal line 30.

As a result, the UP / DOWN counter 17
The value of changes from 00h to 01h. Therefore, the numerical comparison circuit 3 uses the value 00h from the UP / DOWN counter 2 on the microcomputer 1 side and the UP / DO on the phase comparison circuit side.
The value 01h is input from the WN counter 17, but 00h indicating a higher frequency is output.

Since the driving speed of the vibration wave motor 12 is 0, the microcomputer 1 outputs the UP signal to the UP / DOWN counter 2 through the signal line 21 to increase the speed, and the value of the UP / DOWN counter is UP. Then, the drive frequency of the vibration wave motor is lowered to increase the speed detected by the speed detecting means 18 to the target speed UP /
The value of the DOWN counter is controlled to control the vibration wave motor 12 to an appropriate speed.

Here, the vibration wave motor drive frequency for actually driving the vibration wave motor 12 is the smaller of the two numerical values input to the numerical comparison circuit 3 (the higher frequency is the vibration wave motor drive frequency). Is output, the value indicated by the UP / DOWN counter 17 is 01h.
U controlled by the microcomputer 1 when
No matter how the value indicated by the P / DOWN counter 2 changes, the value output from the numerical comparison circuit 3 changes only to 00h and 01h, and the drive frequency of the vibration wave motor also changes only during this period. Also, U controlled by the phase comparison circuit 16
When the value indicated by the P / DOWN counter 17 is the maximum value of the counter such as ffh, the value indicated by the UP / DOWN counter 2 controlled by the microcomputer 1 is input to the A / D converter 4, which causes vibration. The drive frequency of the wave motor is controlled only by the value indicated by the microcomputer.

Next, the operation of the phase comparison circuit 16 will be described. The phase comparison circuit 16 detects the phase difference between the drive signal of the vibration wave motor and the output signal of the sensor at regular time intervals,
If the detected phase value is larger than the set phase value, the UP signal is output to the UP / DOWN counter 17, and if it is smaller, the DOWN signal is output.

If the number of revolutions of the vibration wave motor 12 detected by the speed detecting means 18 is smaller than the target speed, the microcomputer will increase the speed in order to increase the speed.
The value of the DOWN counter is increased to reduce the drive frequency of the vibration wave motor. However, the actual drive frequency of the vibration wave motor 12 is the same as that of the UP / DOWN counter 17 controlled by the phase comparison circuit 16 and the microcomputer 1.
It is determined by the smaller value of the UP / DOWN counter 2 controlled by.

Therefore, if the value of the UP / DOWN counter 17 controlled by the phase comparison circuit 16 is 01h, the frequency for driving the vibration wave motor 12 is the frequency represented by 01h, as shown in FIG. As shown in, the phase difference between the drive signal of the vibration wave motor and the output signal of the sensor is 360 °.
Since it is close to, the phase comparator circuit is UP / DOWN counter 17
To the UP / DOWN counter 17
Increase the count value of. When this operation is repeated at regular intervals, the phase difference between the drive signal of the vibration wave motor and the output signal of the sensor gradually becomes the set value of the phase difference.
When the phase difference approaches the set value of 90 °, the phase comparison circuit 16 outputs a DOWN signal to the UP / DOWN counter 17 and controls the UP / DWON counter 17 to decrease the count value. To do.

As a result, the drive frequency of the vibration wave motor 12 becomes high, and the phase difference between the drive signal of the vibration wave motor and the output signal of the sensor becomes large. If the phase difference at this time becomes larger than the set value of 90 °, the phase detection circuit 16 controls the UP / DOWN counter 17 to increase the count value, and the phase difference becomes larger than the set value of 90 °. When it is smaller, the phase detection circuit 16 controls the count value of the UP / DOWN counter 17 to be smaller. Since the count value of the UP / DOWN counter 2 controlled by the microcomputer 1 is ffh, the drive frequency of the vibration wave motor 12 is UP controlled by the phase comparison circuit 16.
/ DOWN counter 17, the drive frequency of the vibration wave motor 12 is set so that the phase difference between the drive signal of the vibration wave motor and the output signal of the sensor becomes 90 ° which is the set value. UP / controlled by
It is automatically set regardless of the value of the DOWN counter 2.

Up to this point, the control by the microcomputer 1 and the control by the phase comparison circuit 16 have been described separately, but in reality, these two controls are performed simultaneously, and the rotational speed of the vibration wave motor 12 is determined by the microcomputer 1. The phase comparison circuit 17 controls the phase difference between the drive signal and the output of the sensor for properly controlling the rotation of the vibration wave motor 12.

2 and 3, the relationship between the drive frequency of the vibration wave motor 12 and the phase difference between the drive signal and the sensor output is shown by a solid line, and the relationship between the drive frequency and the rotational speed is shown by a dotted line. Figure 2
Indicates that the target speed N is reached when the relationship of the phase difference between the drive signal and the sensor output is larger than 90 ° in a normal state, and FIG. 3 shows the drive frequency of the vibration wave motor 12 and the phase difference and rotation speed. The relationship shows that the target speed is not reached even if the phase difference between the drive signal and the sensor output reaches 90 ° because it varies depending on the load state of the vibration wave motor 12, the temperature, the power supply voltage, and the like.

In the normal state shown in FIG. 2, the rotation speed of the vibration wave motor 12 is higher than the rotation speed of 90 ° which is the phase difference set value corresponding to the drive frequency at which the target speed N is reached.
Therefore, since a phase larger than 90 ° is always input to the phase comparison circuit, U controlled by the phase comparison circuit is used.
The value of the P / DOWN counter 17 is increased by the UP signal every time phase comparison is performed, and reaches ffh. Further, at this time, since the microcomputer 1 controls the drive frequency so that the speed of the vibration wave motor 12 becomes N, the numerical comparison circuit 3 outputs the value of the UP / DOWN counter 2 controlled by the microcomputer 1. Therefore, it is controlled according to the instruction of the microcomputer 1.

In the state shown in FIG. 3, the phase difference between the drive signal and the sensor output at the drive frequency at which the rotation speed of the vibration wave motor 12 reaches the target speed N is smaller than the phase setting value of 90 °. Therefore, when the microcomputer 1 lowers the drive frequency in order to set the rotation speed of the vibration wave motor 12 to the target speed N, the drive signal and the sensor are detected before the rotation speed of the vibration wave motor 12 reaches the target value N. The phase difference with the output reaches 90 °. As a result, the phase comparison circuit 16
The value of the UP / DOWN counter 17 controlled by the UP / DOWN counter is controlled by the microcomputer 1.
It becomes smaller than the value of the counter 2, the output of the numerical comparison circuit 3 becomes the value of the UP / DOWN counter 17 controlled by the phase comparison circuit 16, and the vibration wave motor 12 has a phase difference of 90 ° between the drive signal and the sensor output. Controlled to be
When the speed of the vibration wave motor 12 does not reach the target speed, the vibration wave motor 12 is controlled so as to rotate at the highest rotation speed within a stable rotation range.

As described above, the phase difference between the drive signal and the sensor output by which the vibration wave motor 12 can be stably rotated is 90 °.
If the target speed is reached at a larger value than the above, the microcomputer 1 controls the phase. If the phase difference between the drive signal and the sensor output reaches 90 ° before the target speed is reached, the phase comparison circuit 16 controls the phase difference. Controlled.

[0034]

As described above, in the vibration wave motor drive circuit according to the present invention, the first variable frequency oscillator control means (first counting means) and the second variable frequency oscillator control means (second Counting means), and selection means for automatically selecting one of the output values of the first and second variable frequency oscillator control means, which output has a higher frequency, and inputting the output to the variable frequency oscillator. By providing the vibration wave motor, even if the frequency lower than the frequency at which the vibration wave motor is stably driven is set by the microcomputer, the vibration wave motor is always set by the set phase difference (the phase of the driving AC signal and the sensor electrode). The difference between the detected vibration and the detected phase is controlled so that the microcomputer does not exceed the phase difference limit value when starting the vibration wave motor. After it is possible to control the vibration wave motor without the need to monitor constantly the phase difference of the aforementioned microcomputer. Therefore, the vibration wave motor drive circuit of the present invention does not require the high-performance microcomputer required in the conventional drive circuit, and therefore can be manufactured at a lower cost than the conventional device. Further, in the vibration wave motor drive circuit of the present invention, when the speed control of the motor is performed, the drive control is performed only according to the speed detection information (that is, without requiring the above-mentioned phase difference detection information). It is simple and can be as simple as control of a DC motor.

[Brief description of drawings]

FIG. 1 is a block diagram showing a vibration wave motor drive circuit of the present invention.

FIG. 2 is a diagram showing a relationship between a driving frequency of a vibration wave motor, a speed, and a phase difference.

FIG. 3 is a diagram showing a relationship between a driving frequency of an oscillatory wave motor, a speed, and a phase difference.

FIG. 4 is a diagram showing characteristics of a vibration wave motor.

FIG. 5 is a block diagram showing a drive circuit of a conventional vibration wave motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Microcomputer 2 ... UP / DOWN counter 3 ... Numerical value comparison circuit 4 ... A / D converter 5 ... Variable frequency oscillator 6 ... Dynamic wave motor drive logic 12 ... Dynamic wave motor 15 ... Phase detection circuit 16 ... Phase comparison circuit 17 ... UP / DOWN
counter

Claims (1)

[Claims] 1. A variable frequency oscillator, phase shifting means for generating two alternating signals having different phases from the output of the variable frequency oscillator, at least one of the alternating signals and a vibration of a vibration wave motor. A phase difference detecting means for detecting a phase difference from the state detection signal, and applying the AC signal to the vibrator of the vibration wave motor to drive the motor, the vibration wave motor drive circuit comprising: A phase difference comparing means for comparing the generated phase difference and the phase difference detected by the phase difference detecting means, a first variable frequency oscillator control means controlled according to an output of the phase difference comparing means, The second variable frequency oscillator control means for controlling the speed of the vibration wave motor, and the higher frequency of the output of the first variable frequency oscillator control means and the output of the second variable frequency oscillator control means Vibration wave motor driving circuit and further comprising a selection means for inputting to output to said variable frequency oscillator, a.