| 摘要 |
PURPOSE:To facilitate a decision on the size of a record disk and to prevent malfunction, by providing a gate means controlled by the output signal of a quartz lock signal generating means. CONSTITUTION:A phono motor uses a direct drive motor, and when the quartz lock signal generating means 6 of a controller for said motor is utilized to output a signal from it, namely, only when a turntable is turned at a specified speed, an AND gate 7 is opened to output the output signal of a photodetector 5. The photosensor 5a of the photodetector 5 may use a phototransistor 9. Even if light strikes the photosensor through the gap between a record 3 and the turntable 1, this time is shorter than the low-speed turning, so even if this signal is integrated, the peak value of the output does not reach the threshold value of a comparator 11, so that no malfunction is caused. |
