| 摘要 |
PURPOSE:To attain the accurate tracking control by using a differential voltage transformation means and a means which gives the synchronization detection to the output of said transformation means with a prescribed frequency and then using the detection output as a position control signal which drives a housing holding an actuator. CONSTITUTION:Coils 15 and 16 are wound round magnets 11 and 12 with phases opposite to each other and in an approximately equal number of turns. Thus a differential voltage transformation means 17 is obtained. This means 17 serves as a secondary coil against a tracking coil 10 serving as a primary coil to produce the induced electromotive force in response to the variation of a magnetic flux. Thus the difference is produced with the voltage which is induced according to the relative position of the coil 10 according to the displacement of the center position (reference position) of an actuator. Both terminals of coils 15 and 16 which are set opposite to the coil 10 are connected to a synchronization detecting circuit 21 and extract only the signal having the same frequency as a reference signal out of the differential output between both coils 15 and 16. While the output of the circuit 21 is connected to a feed motor 7 via a driver 22. Then the motor 7 is driven with control so that the actuator is positioned at the center of a housing according to the output of the circuit 21. |
