JPS62203574A - Drive control circuit for supersonic motor - Google Patents

Abstract

PURPOSE:To resonate or oscillate a supersonic motor at driving time by forcibly shifting a drive frequency in a resonance frequency direction at driving time without respect to phase comparison of the output of a sensor electrode with a drive signal to a drive electrode. CONSTITUTION:When a switch 11 is opened in case of driving, the output of a VCO 4 is input through an AND gate 9 and a capacitor 10 to the VCO 4. Accordingly, even if a supersonic motor (SSM) is not vibrated when the SSM is driven and a comparator 1 continuously outputs a low voltage, a capacitor 3 is charged, the output of a VCO 4 is forcibly shifted to a high frequency side, shifted to a resonance frequency side, and driven by the shifted frequency. After driving, the switch 11 is closed, and the VCO 4 is controlled by the comparator 1.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention generates progressive vibration waves using an electro-mechanical energy conversion element such as an electrostrictive element, a magnetostrictive element, or a piezoelectric element,
The present invention relates to an ultrasonic motor drive circuit that drives a rotor using the vibration waves.

<Prior art> When driving and controlling the ultrasonic motor of the above type (hereinafter referred to as SSM) in a resonant state, the driving state of the motor is monitored with a sensor electrode, and the phase difference between the monitor signal and the driving frequency signal of the SSM is detected. In Japanese Patent Application No. 60-226566, the applicant has proposed a type of drive control in which the drive frequency of the SSM is adjusted to make the phase difference a specific value.

FIG. 2 is a block diagram showing an SSM drive circuit showing the control system shown in Japanese Patent Application No. 60-226566.

In the figure, l is a phase comparator circuit, 2 detects the phase difference of the input signal, and when the phase difference has a specific relationship (same phase), the output becomes an oven state, and in response to the rising signal to the R input, When the rising signal of the S input is in a slow phase difference state, a high output is shown for the period of the difference in the rising signals mentioned above, and conversely, when the rising signal of the S input is in a fast phase difference state with respect to the rising signal to the trap input, the above-mentioned It shows the low output during the difference between the rising signals.

2.3 is a resistor and a capacitor that constitute a low-pass filter; the output potential of the capacitor 3 is charged when the output of the comparator circuit is high, and goes up to A-; when it is low, it is discharged and goes down; and when the output is in the oven, the output potential is Holds potential.

4 is a voltage controlled oscillator (hereinafter referred to as VCO) that outputs a signal with a duty ratio of 50% at a frequency corresponding to the input voltage; 5 is a shifter that shifts the phase of the signal from the VCO to the 0° and 90'' phase-related pulses, and its output is sent via an amplifier 6.7 to the drive '7i! pole of the stator 8 on which the electrostrictive element is arranged. 8-
1.8-2 is applied. 8-3 detects the output of the electrostrictive element of the stator and detects the vibration state of the stator! It shows sensor electrodes that send out output in response to breath. In this configuration, the frequency signal applied to the drive electrode 8-2 and the sensor electrode 8
A comparison circuit 1 compares the phase difference between the -3 output frequency signals, and if the result of the comparison is that there is no phase difference, the VCO 4 maintains its oscillation state. In this case, the electrode 8-3 is provided on an electrostrictive element that is placed at a position that is in a resonant state when the phase of the drive signal to the electrode 8-2 and the phase of the signal generated by the electrode 8-3 are the same. It is assumed that Therefore, when there is no phase difference, the SSM continues to be driven at the resonant frequency.

Also, when the signal on the electrode 8-3 has a phase difference that is more advanced than the signal on the electrode 8-2, a high signal is sent from the comparator circuit, so the voltage on the capacitor 3 increases to H1, which causes the VCO4 frequency increases. When the frequency of the drive No. 48 to the drive electrode increases R-, the vibration state of the stator l changes, and the SSM system is designed so that the phase difference between the output signal of the TL electrode-3 and the signal applied to the electrode 8-2 decreases. Since this is configured, the frequency of the VCO 4 is controlled to a value that eliminates the phase difference between the two inputs of the comparator circuit 1, and the comparator circuit 1 shifts to a resonant state. or,
What is the signal from electrode 8-3? i! When a phase difference state occurs that lags behind the signal to the pole 8-2, a low signal is output from the comparator circuit 1, and the potential of the capacitor 3 decreases. Therefore, in this case, the frequency of the VCO 4 decreases, and as described above, the input signal to the comparator circuit shifts to a frequency at which the difference disappears, and is driven resonantly.

In this way, when controlling the drive of the SSM using phase difference comparison, the SSM can always be controlled in a resonant state, and the SSM
Although it is very suitable as an SM drive circuit,
When the SM is driven, the VCO 4 is fixed at a low frequency, and there is a possibility that the resonant frequency may not be reached.

That is, in the initial state when the SSM is driven, the potential of the capacitor 3 is grounded, and the lowest frequency is selected for the VCO 4, and when the power supply is plugged in in this state, the SS
M is driven. If the SSM does not vibrate normally at this time, the output of comparator circuit 1 becomes low and attempts to lower the frequency of the VCO.
The output frequency of is fixed in that state and cannot be shifted in the direction of the resonant frequency.

<Purpose> The present invention has been made in view of the above-mentioned matters, and is an ultrasonic motor that uses the drive frequency a$ control method based on the phase comparison. By shifting to , the ultrasonic motor can resonate and oscillate during driving.

<Embodiment> FIG. 1 is a circuit diagram showing an embodiment of a drive control circuit for an ultrasonic motor according to the present invention, and the same components as those in FIG. 2 are given the same symbols.

In the figure, 11 is a switch that is turned off when driving the SSM, 9 is an AND gate, and 10 is an AC coupling capacitor. When the switch 11 is turned off during driving, the output of the VCO 4 is connected to the AND gate 9 and the capacitor lO.
It is manually operated by V C'04 via VC'04. Therefore, even if the SSM does not vibrate when the SSM is driven and the low signal continues to be output from the comparator circuit 1, the capacitor 3 is charged and the output of the VCO 4 is forcibly shifted to the high frequency side, and the capacitor is shifted to the resonant frequency side. and driving is performed at the shifted frequency. Therefore, since the frequency to SSM is in the resonance direction, S
After the SM starts vibrating, the phase difference control described above is performed.

Note that the switch 11 is turned on after being driven, and the gate 9 becomes low, so that after being driven, the control rJ11 is performed in exactly the same manner as in the case of FIG.

3 and 4 are circuit diagrams showing the configuration of main parts in another embodiment of the present invention, and the same components as in the embodiment of FIG. 1 are given the same symbols.

In Figure 3, +4 is an oscillation circuit, and 11' is a when driving.
This is a switch that connects to the side and switches to the side after driving. In the embodiment shown in FIG. 3, the output of the oscillation circuit 14 is input to the capacitor 3 via the capacitor 10 via the switch 11' during driving, and the frequency of the VCO 4 is shifted during driving.

Further, in FIG. 4, during driving, the output of the oscillation circuit 14 is directly transmitted to the capacitor 3 via 1r, the frequency of the VCO 4 is shifted, and the switch 11'' is turned off after driving.

Effect> As described above, in the invention, the phase difference between the output of the sensor T electrode and the drive signal to the drive electrode is compared, and the drive frequency is controlled so that the phase difference is in a specific state. In ultrasonic motors that generate resonance oscillation, the driving frequency is forcibly shifted toward the resonance frequency, regardless of the phase comparison described above, so there are problems when driving the above types of ultrasonic motors. It is possible to eliminate this.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a drive circuit for an ultrasonic motor according to the present invention, Fig. 2 is a circuit diagram showing a drive circuit for a conventional ultrasonic motor, and Fig. 3 shows another embodiment of the invention. Circuit Diagram FIG. 4 is a circuit diagram showing still another embodiment of the present invention. ! --- Comparison time v6 9 --- AND gate 3-- capacitor 4 --- VCOl 3
L+

Claims (1)

[Claims] A detection means for applying a frequency voltage to a vibrating body provided with an electro-mechanical energy conversion element to generate a progressive vibration wave in the vibrating body, driving a moving body with the vibration wave, and detecting the vibration of the vibrating body. In an ultrasonic motor that compares the phase difference between the output of the vibration wave motor and the frequency voltage applied to the vibrating body, and controls the frequency of the frequency voltage so that the phase difference has a specific relationship based on the comparison result, when the vibration wave motor is driven. A drive control circuit for an ultrasonic motor, comprising a shift circuit that shifts the frequency of the frequency voltage independently of the comparison result.