Ultrasonic motor device

Abstract

An ultrasonic motor device includes: an ultrasonic motor that moves an object; a detecting unit that detects movement of the object; and a control unit that drives the ultrasonic motor according to a first driving signal before detection of the movement of the object, and drives the ultrasonic motor according to a second driving signal, which is different from the first driving signal, after detection of the movement of the object.

Description

INCORPORATION BY REFERENCE [0001] The disclosures of the following priority application are herein incorporated by reference: [0002] Japanese Patent Application No. 2005-157162, filed May 30, 2005 BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates to an ultrasonic motor device for controlling driving of an ultrasonic motor. [0005] 2. Description of the Related Art [0006] There is known a control device for controlling driving of an ultrasonic motor while feeding back output from a speed detector such as an encoder. (see Japanese Laid-open Patent Publication No. 2003-304691) SUMMARY OF THE INVENTION [0007] However, in the event of driving the ultrasonic motor with backlash between gears, movement of the ultrasonic motor is not detected until the backlash has been taken up, even though the ultrasonic motor is actually moving. Accordingly, the feedback control results in acceleration, and moving too fast in turn bumps away the article to b...

AI Technical Summary

Benefits of technology

[0019] According to the 12th aspect of the invention, a control method for controlling an ultrasonic motor device comprises: driving of an ultrasonic motor according to a first driving signal; detecting of movement of an object moved by the ultrasonic motor; and driving of the ultrasonic motor according to a second driving signal which differs from the first driving signal, following detection of the movement of the object.

[0020] According to the 13th. A control method according to the 12, wherein, in an event that the ultrasonic motor is driven according to the first driving signal for a predetermined amount of time before detection of the movement of the object, control mode is switched to a mode in which the ultrasonic motor is driven according to the second driving sign

Problems solved by technology

However, in the event of driving the ultrasonic motor with backlash between gears, movement of the ultrasonic motor is not detected until the backlash has been taken up, even though the ultrasonic motor is actually moving.

Accordingly, the feedback control results in acceleration, and moving too fast in turn bumps away the article to be controlled at the point that the backlash runs out, and then backlash is generated again.

Such effects of backlash being repeated have been problematic in proper control.

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