| 摘要 |
PROBLEM TO BE SOLVED: To provide an oscillation motor drive circuit by which a motor can be controlled at low costs, with high accuracy and at high speed. SOLUTION: A current amplifier 74 supplies a drive current Id to a drive coil 81 of oscillation motor 8 on the basis of a control voltage Ve which is output from an error amplifier 73. A magnetic angular-displacement sensor 9 outputs, across output terminals 9a, 9b, a voltage which is proportional to the intensity of a magnetic field. A first differential amplifier 71 amplifies the output voltage of the magnetic angular-displacement sensor 9, and an amplified voltage Vh is output. By a current-to-voltage conversion circuit 75, the drive current Id which flows to the drive coil 81 of the motor 8 is converted into a voltage Vd. By a second differential amplifier 72, the output voltage Vd of the current-to-voltage conversion circuit 75 is subtracted from the output voltage Vh of the first differential amplifier 71, and a subtraction result is output as a difference voltage Vs. An error amplifier 73 generates a control voltage Ve in such a way that the difference between the voltage of an optical scanning control signal and the difference voltage Vs to be output from the second differential amplifier 72 becomes small. |
