Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Hiromi Tanoue

Kenichiroh Takahashi

Noriyuki Harao

Taro Kishibe

Ritsuo Inaba

Takahiro Masuda

Koji Kameda

Toru Kishi

Hirokazu Yamasaki

Nobukazu Sugano

Yukihiro Matsuyama

Horiyuki Harao

Ken-ichiroh Takahashi

A position detector has a peak detector for detecting peak values of an Asignal and a Bsignal serving as output signals of an analog to digital (AD) converter, an offset/amplitude correction section for generating an Asignal and a Bsignal by correcting offsets and amplitude errors using the peak values detected by the peak detector, and a position data conversion section for converting the sinusoidal signals of an A phase and a B phase into position data.

Phase correction circuit of encoder signal

A motor controller includes a motor-position detector, a motor driver and a power cable having a pair of electric lines (two lines) which feeds power from the driver to the detector. The detector superimposes serial information about the motor-position to the power cable via windings of a transformer or a coupling capacitor. The serial information is obtained by converting parallel information about the motor-position. The serial information superimposed travels to the driver via the power cable. The driver receives the serial information via windings of the transformer or a coupling capacitor, and converts it to parallel information. The driver drives the motor according to this parallel information. The information necessary for driving the motor is superimposed to the power cable and transmitted through the power cable, so that a number of electric lines between the detector and the driver can be minimized.

Motor controller with position detector

A driving apparatus for an ultrasonic motor which generates a driving force by using a piezoelectric member, wherein an oscillation frequency fd is varied so as to follow a driving frequency fm which is particular to a mechanical resonance frequency fro when the mechanical resonance frequency fro varies by influence of environment. For this purpose, current and voltage detectors are provided for respectively detecting the current corresponding to the mechanical vibration of the piezoelectric member and the voltage impressed on the piezoelectric member. The phase difference between the detected current and voltage is detected, and this phase difference is used to drive a variable frequency oscillator so as to maintain the phase difference constant. The output of the variable frequency oscillator is then used to drive the driving circuit for the piezoelectric member of the ultrasonic motor.

Driving apparatus for ultrasonic motor

In a driving apparatus for ultrasonic motor, a variable oscillator (44) varies oscillating frequency responding to current level of detected current which flows to a piezoelectric member (1, 2) and is in proportion to mechanical vibration of the piezoelectric member (1, 2) when mechanical resonance frequency varies by change of environmental condition.

In a driving circuit for a piezoelectric ultrasonic motor (23) supplying driving signal from an astable oscillator (51), which comprises an oscillation IC (49), a capacitor (48) and charge-discharge resistors (45, 46, 47), is controlled by controlling leakage current through a leakage resistor (47) to a point E, through controlling of the voltage of the point E by a temperature-dependent voltage producing circuit 52.

In a driving apparatus for an ultrasonic motor, which motor has a stator comprising a pair of piezoelectric members for generating travelling mechanical vibrations, the driving apparatus has an oscillator, a phase shift circuit, and delay circuits. By deferring phases of two control signals for two switching devices, there is no fear of dangerous simultaneous turn-ons of the switching devices.

Growing community of inventors

Nara, Japan

Hiromi Tanoue