| 摘要 |
PURPOSE:To reduce the fluctuation of moving speed by providing an amplitude detection means of mechanical arm current and by correcting the detected gain of the mechanical arm current in temperature under the working environmental temperature of a motor. CONSTITUTION:An ultrasonic motor drive circuit connects a piezoelectric body 9 and a temperature sensing resistance element 5 in series to an electrode section of a motor section. At the same time it connects a capacitor 11 of a capacity equal to the capacity C0 in a working environmental maximum temperature of a piezoelectric body to a fixed resistance element 6 in series and connects them to the above series connection body in parallel. The difference 14 of each potential between the temperature sensing resistance element 5 and the fixed resistance element 6 is found and the mechanical arm current (f) is detected. This current (f) is then compared with the set value (h) with its current amplitude controller 12 through an amplitude detector 13. A voltage control frequency oscillator 1 outputs a designated driving frequency signal (a) based on the frequency control signal (i) and applies driving signals (e) and (d) to the electrode section 7, etc., through a 90 deg. phase setter 2, etc. The driving frequency is thereby decided according to the amplitude of mechanical arm current and the fluctuation of rotating speed is reduced. |
