| 摘要 |
PURPOSE:To heighten detecting accuracy by a smiple structure, by agreeing the counting start points of a count and memory means for a sensor-arm and a count and control means for a tone-arm. CONSTITUTION:Light passing through a slit 10 by the scan of a sensor-arm 2 on a record 1 is detected by means of a light receiving element 13, and count 18 is cleared when detecting signals reach reference value at a comparison circuit 17. Detecting signals by means of a light receiving element 12 for light passing through slits 9 are counted by means of a counter 18 through a comparison circuit 16, the operation is repeated with the turning of the arm 2 and count value in the case when the change of reflected light between the curve reaches locations detected by means of a detector 3 is memorized at a memory circuit 19. Detecting signals by means of a light receiving element 32 for light passing through a slit 29 clear a counter 37 when tone-arm 1 turns, and a comparison circuit 38 stops the revolution of an arm 20 when the number of slits 28 by means of a light receiving element 31 is identical to the memory value of the circuit 19 by means of the counter 37. |
