| 摘要 |
PURPOSE:To correct uneven rotation due to eccentricity of a disc by storing an eccentric data of the disc while the disc is turned at least once, and changing a threshold level obtained from waveform shaping of the output of a rotary detector based on the stored content. CONSTITUTION:An output signal of a waveform shaping circuit 5 and a reference signal are compared by a phase comparator at first via a switch S4 and the result is fed to a DC motor. The disc and a slit disc of an encoder are fixed to the rotary shaft of the motor and a sinusoidal wave signal from the encoder is shaped by the circuit 5. Further, a signal recorded on the disc is read and counted by a counter 6 at each region, a microcomputer 7 calculates the data of deflection and the result is latched by a latch circuit 8. In driving the motor while the eccentricity is corrected, the output of the circuit 5 is converted into a triangle wave by a waveform shaping circuit 9, binary-coded by the output of a threshold level generating circuit 11 to control the motor. Thus, uneven rotation is prevented in such a way. |
