PURPOSE: To protect a circuit from the electromotive voltage which is generated in an oscillatory wave motor by an external force, by interposing a switch, which is turned on during the driving control time of the oscillatory wave motor, between an electro-mechanical energy transducing means and its driving circuit.
CONSTITUTION: When switches 53 and 54 are turned on, electrostrictive elements 3a and 3b are connected to driving circuits 49 and 50, and oscillatory waves are generated in a fixed body to extend a lens barrel to an in-focus region. When an electric manual changeover switch 31 is turned on to select the manual driving during the driving control time of the oscillatory wave motor, a switching circuit 36 outputs a low-level signal to turn off a switch 51. Therefore, power is not supplied to driving circuits 49 and 50 independently of the positon of a release button, in a stroke and electro-strictive elements 3 which is the electromechanical energy transducing means are not operated. Consequently, driving circuits 49 and 50 and etc. are protected even if a counter electromotive voltage is generated in electrostrictive elements 3.
MURAKAMI HIROYASU
HIRAMATSU AKIRA
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