| 摘要 |
PURPOSE:To detect each size of a record disk with accuracy by exercising control by detecting signals of a closed part and open part, provided to a shutter plate turning together with a tone arm in a body, by one sensor. CONSTITUTION:Shutter plate 4 is provided which turns together with arm axis 2 of tone arm 1 in a body and at the same circumference of this shutter plate 4, closed parts 10 and 11 and open part 12 of widths corresponding to sizes of record disks are provided. Then, one sensor composed of light emission part 14 and photodetection part 13 is provided which detects sequentially edge parts E1, E2 and E3 in the circumferential directions of those closed parts 10 and 11 and open part 12, and the 1st detection signal of this sensor and the 2nd detection signal obtained by selecting or detecting the side of a record disk are used to control the stop of driving motor 6 of tone arm 1 by a provided control circuit, so that the lowering position of tone arm 1 will be detected. |
