JP2667811B2 - Vibration type motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an electrostrictive element, a magnetostrictive element, a piezoelectric element and the like.
The present invention relates to a vibration-type motor drive circuit that uses a mechanical energy conversion element to generate a progressive vibration wave and drives the rotor with the vibration wave. <Prior Art> When a vibration type motor (hereinafter referred to as SSM) of the above type is driven and controlled in a resonance state, a driving state of the motor is monitored by a sensor electrode, and a phase difference between the monitor signal and a driving frequency signal of the SSM is measured. The applicant of the present application has proposed in Japanese Patent Application No. 60-226566 a drive control of a type for adjusting the drive frequency of the SSM so as 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 the Japanese Patent Application No. 60-226566. In the figure, 1 is a phase comparison circuit, 2 detects the phase difference of the input signal, and when the phase difference is in a specific relationship (the same phase), the output is in an open state, and a rising signal to the R input is When the rising signal of the S input is in the late phase difference state, it indicates a high output during the period of the difference of the rising signal. Conversely, when the rising signal of the S input is in the early phase difference state with respect to the rising signal to the R input, The row output is shown during the difference between the rising signals. Reference numerals 2 and 3 denote a resistor and a capacitor constituting a low-pass filter. The output potential of the capacitor 3 is charged and rises when the output of the comparison circuit is high, discharged and falls when the output of the comparison circuit is low, and decreases when the output of the comparison circuit is open. Hold. 4 is a voltage controlled oscillator (hereinafter referred to as VCO) that outputs a signal with a duty ratio of 50% at a frequency according to the input voltage. 5 is VCO
Is a shifter that shifts the phase of the signal from the phase shifter to a phase-related pulse of 0 ° and 90 °, and outputs the drive electrodes 8-1,8- of the stator 8 on which the electrostrictive element is disposed via the amplifiers 6,7. 2 is applied. Reference numeral 8-3 denotes a sensor electrode that detects the output of the electrostrictive element of the stator and sends the output according to the vibration state of the stator. In this configuration, the comparison of the phase difference between the frequency signal applied to the drive electrode 8-2 and the output frequency signal of the sensor electrode 8-3 is performed by the comparison circuit 1, and when there is no such phase difference, the VCO4 Keeps its oscillation state.
In this case, the phase of the drive signal to the electrode 8-2 and the phase of the electrode 8
It is assumed that the electrode 8-3 is provided in the electrostrictive element arranged at a position where the generated signals of −3 are in a resonance state when the phases thereof are the same. Therefore, when there is no phase difference, the SSM continues to be driven at the resonance frequency. When the signal of the electrode 8-3 is in a phase difference state advanced from the signal to the electrode 8-2, a high signal is sent from the comparison circuit, so that the voltage of the capacitor 3 rises.
VCO4 frequency increases. When the frequency of the drive signal to the drive electrode rises, the vibration state of the stator 1 changes and the electrode 8-
Since the SSM system is configured so that the phase difference between the output signal of the third circuit 3 and the signal applied to the electrode 8-2 is reduced, the frequency of the VCO4 is set to a value that eliminates the phase difference between both inputs of the comparison circuit 1. Is shifted to the resonance state. Further, when the signal of the electrode 8-3 is in a phase difference state delayed from the signal to the electrode 8-2, a low is output from the comparison circuit 1 and the capacitor 3
Potential drops. Therefore, in this case, the frequency of VCO4 decreases, and the frequency shifts to a frequency at which the phase difference of the input signals to the comparison circuit disappears as described above, and resonance driving is performed. As described above, in the SSM drive control based on the phase difference comparison, the SSM can always be driven and controlled in a resonance state, which is very suitable as a drive circuit of the SSM. There is a possibility that the frequency remains fixed at the low frequency and does not become the resonance frequency. That is, in the initial state when the SSM is driven, the potential of the capacitor 3 is grounded, the lowest frequency of the VCO 4 is selected, and when the power is turned on in this state, the SSM is driven. At this time, if the SSM does not oscillate normally, the output of the comparison circuit 1 goes low to try to lower the frequency of the VCO. The output frequency is fixed in that state and cannot be changed in the resonance frequency direction. <Purpose> The present invention has been made in view of the above-described matters, and has, as a configuration thereof, a first electro-mechanical energy conversion element portion and a second electro-mechanical energy conversion element portion arranged on a vibrating body. In a vibration type motor device for applying a driving frequency signal having a different phase to vibrate a vibrating body to obtain a driving force, a third electro-mechanical energy conversion element unit for detecting a vibration state is arranged on the vibrating body, and The frequency signal generated in the third electric-mechanical energy conversion element section and the first electric-
When the phase of the driving frequency signal is compared with the driving frequency signal applied to the mechanical energy conversion element, the resonance frequency is higher when the phase of the driving frequency signal is earlier than the frequency signal generated in the third electro-mechanical energy conversion element. A phase comparison circuit that outputs a signal indicating that the resonance frequency is lower than the frequency of the current driving frequency signal, and a signal indicating that the resonance frequency is lower than the frequency of the current driving frequency signal based on the comparison result of the comparison circuit And a shift circuit that forcibly shifts the frequency of the driving frequency signal to the high frequency direction at the time of start-up. The above problem is solved in the vibration type motor of the type in which the resonance state is detected and drive control is performed. <Embodiment> FIG. 1 is a circuit diagram showing an embodiment of a drive control circuit for a vibration type motor according to the present invention, and the same components as those in FIG. 2 are denoted by the same reference numerals. In the figure, 11 is a switch that is turned off when the SSM is driven, 9 is an AND gate, and 10 is an AC coupling capacitor. When the switch 11 is turned off during driving, the output of VCO4 passes through the AND gate 9 and the capacitor 10 and becomes VCO4.
Is input to Therefore, when driving the SSM, the SSM does not vibrate,
Even when the row is continuously output from the comparison circuit 1, the capacitor 3 is charged and the output of the VCO 4 is forcibly shifted to the high frequency side, shifts to the resonance frequency side, and the drive is performed at the shifted frequency. You. Therefore, since the frequency to the SSM is in the resonance direction, the SSM starts oscillating and thereafter the phase difference control is performed. The switch 11 is turned on after driving, and the gate 9 is set low by this, so that after driving, the control is performed in the same manner as in the case of FIG. FIG. 3 and FIG. 4 are circuit diagrams showing the configuration of main parts in another embodiment of the present invention, and the same symbols are given to the same components as those in the embodiment of FIG. In FIG. 3, 14 is an oscillating circuit, and 11 'is a switch which is connected to the side a during driving and is switched to side b after driving. In the embodiment shown in FIG. 3, an oscillating circuit is provided via a driving switch 11 '.
The output of 14 is input to the capacitor 3 through the capacitor 10 and shifts the frequency of VCO4 during driving. In FIG. 4, the output of the oscillating circuit 14 is directly transmitted to the capacitor 3 via the drive 11 "to shift the frequency of the VCO 4, and the switch 11" is turned off after the drive. <Effects> As described above, according to the present invention, the vibration type motor that compares the phase difference between the output of the sensor electrode and the drive signal to the drive electrode, detects the resonance drive state, and controls the drive frequency, Since the driving frequency is forcibly shifted in the direction of the resonance frequency irrespective of the phase comparison, it is possible to solve the problem at the time of driving the vibration type motor of the above type.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing a driving circuit of a vibration type motor according to the present invention, FIG. 2 is a circuit diagram showing a driving circuit of a conventional vibration type motor, and FIG. FIG. 4 is a circuit diagram showing another embodiment, and FIG. 4 is a circuit diagram showing still another embodiment of the present invention. 1 ... Comparison circuit, 9 ... And gate 3 ... Capacitor, 4 ... VCO.

Claims (1)

(57) [Claims] A driving frequency signal having a different phase is applied to the first electro-mechanical energy conversion element and the second electro-mechanical energy conversion element disposed on the vibrating body to vibrate the vibrating body to reduce the driving force. In the vibration type motor device to be obtained, a third electro-mechanical energy conversion element for detecting a vibration state is disposed on a vibrating body, and a frequency signal generated in the third electro-mechanical energy conversion element and the first electric-mechanical energy conversion Is compared with the driving frequency signal applied to the electro-mechanical energy conversion element section, and the phase of the driving frequency signal is earlier than the frequency signal generated in the third electro-mechanical energy conversion element section. A phase comparison circuit that outputs a signal indicating that the time resonance frequency is lower than the frequency of the current driving frequency signal, and the comparison result of the comparison circuit indicates that the resonance frequency is lower than the frequency of the current driving frequency signal. And an adjusting circuit that shifts the frequency of the driving frequency signal to a lower frequency direction when a signal indicating that the driving frequency signal is lower than that of the driving frequency signal, and forcibly shifts the frequency of the driving frequency signal to a higher frequency direction at startup. A vibration type motor device comprising a shift circuit.