Ultrasonic motor and electronic device with ultrasonic motor
AssigneeSeiko Instruments Inc.
InventorsAkihiro Iino, Kenji Suzuki, Masao Kasuga
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Abstract
In a self-excited oscillator circuit, a buffer is connected to an electrode or electrodes, and a buffer and an inverter are connected to an electrode or electrodes. Each of the inverters and and the buffer has a tri-state configuration and is capable of setting an output terminal in a high-impedance state, i.e., turning off an output signal, according to a signal input to a control terminal. Therefore, it is possible to turn off a drive circuit and the ultrasonic motor by setting the inverter in the high-impedance state. It is also possible to change the direction of movement of the moving member by setting one of the buffer and the inverter in the high-impedance state.
Claims24
An ultrasonic motor comprising:
- a piezoelectric element having a plurality of driving electrodes and a common electrode;
- a vibrating body driven by the piezoelectric element to undergo vibration in response to a signal applied across the driving electrodes and the common electrode of the piezoelectric element;
- a moving body driven by vibration of the vibrating body;
- a self-excited oscillating circuit having an amplifier circuit for amplifying an output signal of the piezoelectric element and feeding back the amplified output signal as a driving signal to the driving electrodes of the piezoelectric element to cause self-excited oscillation of the vibrating body;
- a common connecting point provided between the amplifier circuit and the plurality of driving electrodes of the piezoelectric element for connecting the plurality of driving electrodes to one point so that all of the driving electrodes are simultaneously driven;
- and
- an inverter provided between the common connecting point and at least one of the driving electrodes of the piezoelectric element for selectively inverting the phase of the driving signal supplied to the at least one driving electrode to control a direction of movement of the moving body.
An ultrasonic motor comprising:
- a vibrating body having a piezoelectric element provided with a plurality of driving electrodes on one surface and a common electrode on another surface;
- a moving body in frictional contact with the vibrating body to undergo movement in response to vibration of the vibrating body;
- a self-excited oscillation circuit having an amplifier for amplifying an output signal of the piezoelectric element and feeding back the amplified output signal to the driving electrodes of the piezoelectric element, a filter circuit for filtering the amplified output signal, and an inverter for selectively inverting the amplified output signal and producing an inverted signal;
- wherein all of the driving electrodes of the piezoelectric element are simultaneously driven by either the amplified output signal or the inverted signal.
Dependencies are inferred from the claim text.