| 摘要 |
PURPOSE:To enable to detect the position of end of playing for two types of different record discs from the diameter, by using a photointerrupter as a pulse generating means and operating the gate start circuit producing pulses respectively through the photodetection and interruption by a photoelectric conversion element. CONSTITUTION:In playing an LP record disc, a selector switch 8 is selected to the 30cm position to start playing disc. In this case, a shutter plate 4 is inserted between a light emitting element 5 and a photoelectric conversion element 6, inhibiting the signal for the 1st start circuit 7 to operate a gate circuit 16. Since the 2nd start circuit 9 produces no signal to the gate circuit 16 at the same time, the drive motor 19 for the tone arm automatic return is not operated. When the playing is finished and light passes through from the through-hole 4a of the shutter plate 4, a signal is fed to the start circuit 20 of the drive motor 19 at the output terminal 16c of the gate circuit 16 with the output from the first gate start circuit 7 for the automatic return of the tone arm. |
