JPH08275560A - Ultrasonic motor driver - Google Patents

Abstract

PURPOSE: To obtain a driver for an ultrasonic motor in which a drive body touching a piezoelectric vibrator can be driven stably. CONSTITUTION: Output from a voltage controlled vibrator 10 is fed to a phase decision circuit 2 which delivers output of two phases to a control circuit 3. Output from the control circuit 3 is fed to a drive circuit 4 which delivers two outputs, respectively, to an electrode 6a on one surface of a piezoelectric vibrator 6 and split electrodes 6a, 6b on the other surface thereof so that the vibration direction can be switched. A current signal detection circuit 8 detects a feedback signal from one of two outputs from a drive circuit 2. The feedback signal is amplified through a feedback amplifier 9 and fed through a phase correction circuit 11. The feedback signal is then compared through a phase comparator 12 with the output from a voltage controlled oscillator 10 and the difference is inputted to the voltage controlled oscillator 10 thus controlling the phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor driving device for stably driving a driving body in contact with a piezoelectric vibrator.

[0002]

2. Description of the Related Art As an ultrasonic motor drive device proposed by the present applicant, as shown in FIG. 2, an output of an oscillator 1 is output to a phase determination circuit 2 and two signals from the phase determination circuit 2 are controlled by a control circuit. 3 and the outputs from the control circuit 3 are input to the drive amplifiers 4a and 4b of the drive circuit 4, respectively, and the outputs of the drive amplifiers 4a and 4b are supplied to the piezoelectric vibrator 6 via the transformer 5 with one terminal grounded. While connecting to the electrode 6a adhered to one surface, the divided electrodes 6b and 6c adhered to the other surface of the piezoelectric vibrator 6 are connected to the contacts 7a and 7b of the switching device 7, and the switching terminal 7c is connected to the ground. Further, the feedback signal is detected by the current signal detection circuit 8 from one of the outputs of the drive amplifiers 4a and 4b of the drive circuit 4, and the output of this current signal detection circuit 8 is positively fed back to the oscillation circuit 1. .

In the ultrasonic motor drive device having such a configuration, by switching the switching terminal 7c of the switching device 7, the direction of the drive vibration generated in the piezoelectric vibrator 6 is changed to contact the piezoelectric vibrator 6. The moving direction of the driving body can be changed.

[0004]

However, since the phase of the feedback signal detected by the current signal detection circuit 8 and the phase of the oscillator 1 are not compared in this ultrasonic motor drive device, the piezoelectric vibrator 5 is not always used. There was a problem that it could not be driven stably at the optimum frequency.

[0005]

According to the present invention, the output of a voltage controlled oscillator is divided into two phases by a phase determination circuit, the outputs of the two phases are input to a control circuit, and the output of the control circuit is a drive circuit. To drive the output of the drive circuit to an electrode on one surface of the piezoelectric vibrator, and to connect the divided electrodes on the other surface of the piezoelectric vibrator to switch the vibration direction. A feedback signal is detected by a current signal detection circuit from one of two outputs of the circuit, the feedback signal is amplified by a feedback amplifier, and the feedback signal amplified by the feedback amplifier is phase-corrected by a phase correction circuit. The phase-corrected signal and the output of the voltage controlled oscillator are input to a phase comparator for phase comparison, and the phase difference signal is input to the voltage controlled oscillator to control the output phase.

[0006]

In the present invention, the output of the voltage controlled oscillator is input to the phase determining circuit, the two phase signals of the phase determining circuit are input to the drive circuit, and the signals amplified by the drive circuit are input to the divided electrodes of the piezoelectric vibrator. Drive vibration is generated in the piezoelectric vibrator by inputting to the piezoelectric vibrator through the switching device, the direction of this drive vibration is switched by the switching device, and the driving body pressed against the piezoelectric vibrator is driven. , One of the two signals input to the piezoelectric vibrator is detected by the current signal detection circuit, amplified by the feedback amplifier, this detection signal is corrected by the phase correction circuit, and this phase-corrected signal The output of the oscillator is compared by the phase comparator, and the phase difference signal is positively fed back to the oscillator to correct the phase shift between the output of the voltage controlled oscillator and the fed back signal to synchronize the phase of the entire circuit. Stable movement It can be.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an ultrasonic motor drive apparatus according to an embodiment of the present invention. 2 is a phase determination circuit, 3 is a control circuit, 4 is a drive circuit, 5 is a transformer, and 6 is a piezoelectric vibrator. , 7 is a switching device, 8 is a current signal detection circuit, and 9 is a feedback amplifier. Since these configurations are the same as the configurations of the above-mentioned device, description thereof will be omitted, but in the present embodiment, the oscillator is a voltage controlled oscillator. 10, the detection signal from the current signal detection circuit 8 is amplified by the feedback amplifier 9, and the amplified signal is corrected by the phase correction circuit 11 and input to the phase comparator 12.
In addition, the output from the voltage controlled oscillator 10 is input to the phase comparator 12, the phase comparator 12 compares the output with the phase of the feedback signal from the phase correction circuit 11, and the output having a phase difference between these signals is voltage controlled. The oscillator power is returned to 10.

In this embodiment, as described above, the phase comparator 1
At 2, the phase of the feedback signal from the current signal detection circuit 8 and the phase of the output from the voltage controlled oscillator 10 are compared, and the phase of the feedback signal and the phase of the output of the voltage controlled oscillator 10 are matched to each other. A signal having an optimum frequency can be input, and the driving body that is in contact with the piezoelectric vibrator 6 can be stably driven.

[0009]

As described above, in the ultrasonic motor driving device of the present invention, the output from the voltage controlled oscillator is determined by the phase determining circuit, the control circuit inputs the output to the driving circuit, and the output of the driving circuit is the other. Input to the divided piezoelectric vibrator through the switching device, the feedback signal is detected by the signal detection circuit from the drive circuit, this detection signal is input to the phase comparator, and the output of the voltage controlled oscillator is output. By inputting to the phase comparator to compare the phases and inputting the output of the phase comparator to the voltage controlled oscillator, there is an advantage that the entire circuit can be stably driven.

[Brief description of drawings]

FIG. 1 is a block diagram of an ultrasonic motor drive device according to an embodiment of the present invention.

FIG. 2 is a block diagram of an ultrasonic motor drive device proposed by the present applicant.

[Explanation of reference numerals] 2 phase determination circuit 3 control circuit 4 drive circuit 5 transformer 6 piezoelectric vibrator 7 switching device 8 signal detection circuit 9 feedback amplifier 10 voltage controlled oscillator 11 phase correction circuit 12 phase comparator

Claims (1)

[Claims] 1. An output of a voltage controlled oscillator is divided into two phases by a phase determination circuit, outputs of the two phases are input to a control circuit, outputs of the control circuit are input to a drive circuit, and The output is input to an electrode on one surface of the piezoelectric vibrator, and is connected to a divided electrode on the other surface of the piezoelectric vibrator to switch the vibration direction.
A current signal detection circuit detects a feedback signal from one of the two outputs, the feedback signal is amplified by a feedback amplifier, the feedback signal amplified by the feedback amplifier is phase-corrected by a phase correction circuit, and the phase is corrected. An ultrasonic wave characterized in that the corrected signal and the output of the voltage controlled oscillator are input to a phase comparator to compare the phases, and the phase difference signal is input to the voltage controlled oscillator to control the phase of the output. Motor drive device.