JP2003324975A5

JP2003324975A5 -

Info

Publication number: JP2003324975A5
Application number: JP2002129095A
Authority: JP
Filing date: 2002-04-30
Publication date: 2005-09-29
Anticipated expiration: 2022-04-30

Claims

Two stacked piezoelectric elements arranged in series in the driving direction, an elastic body that holds the stacked piezoelectric element and acts as a vibrating body, a driver, a vibration detecting piezoelectric element, and a contact with the driver A drive circuit for an ultrasonic motor that drives the driven body by generating an elliptical vibration in the driver by simultaneously exciting longitudinal resonance vibration and bending resonance vibration.
A drive signal generation unit configured to generate a drive signal having a 90-degree phase shift applied to the two stacked piezoelectric elements, and changing a frequency of the drive signal with a predetermined width centered on a resonance frequency of the ultrasonic transducer A drive signal generation unit capable of
The drive signal generation unit so that a phase difference between a detection signal of the vibration detection piezoelectric element and a drive signal applied to the stacked piezoelectric element disposed on the front side in the traveling direction of the driven body is within a predetermined range. Control means for controlling
A drive circuit for an ultrasonic motor, comprising:

The drive signal generator is
A pulse generating unit that oscillates the drive signal and can change the frequency of the drive signal with a predetermined width around the resonance frequency of the ultrasonic transducer;
A waveform shaping unit that shifts the output of the pulse generation unit to output at least two rectangular wave signals that are 90 degrees out of phase and performs processing so that the duty ratio is about 50%;
A filter unit having a removal function to remove harmonic components of the output from the waveform shaping unit ;
A power amplifying unit that inputs and amplifies the signal after filtering by the filter unit, generates the drive signal of AC pressure and applies it to the stacked piezoelectric element;
The ultrasonic motor according to claim 1, further comprising: a binarizing unit that binarizes a detection signal detected by the vibration detecting piezoelectric element and supplies the binarized signal to the control unit. Driving circuit.

The control means compares the detection signal from the binarization unit with the drive signal applied to the stacked piezoelectric element disposed on the front side in the traveling direction of the driven body, and based on the comparison result, The ultrasonic motor drive circuit according to claim 2, wherein the transmission frequency by the pulse generation unit is variably controlled so that a phase difference from the drive signal is within a predetermined range.

The power amplifying unit is composed of two switching elements that amplify and generate an AC voltage drive signal by charging and discharging the stacked piezoelectric element respectively.
The ultrasonic motor driving circuit according to claim 2, wherein the waveform shaping unit includes a circuit that shapes a waveform so that the two switching elements are not driven simultaneously.

The vibration detecting piezoelectric element, the ultrasonic motor drive circuit according to any one of claims 1 to 4, characterized in that outputs a detection signal which detected the longitudinal resonance vibration of the ultrasonic vibrator .