| 摘要 |
PURPOSE:To achieve the reduction in retrieval time by jumping the light spot according to the difference between the current track number and assignment number. CONSTITUTION:The signal having been read from a video disc 6 with the photo detector 7 of an optical head 100 is applid to a tracking circuit 12 and demodulating circuit 11. The current number of the track having been demodulated with the circuit 11 and having been detected with an address detection crcuit 14 is compared with the assignment address having been assigned with a keyboard 16 and an arithmetic circuit 23. The signal corresponding to the difference is applied to a down counter 27 which down-counts with the jump pulses of a jump assignment circuit 26 via the finish judgement circuit 25 which is connected to a judgement circuit 24 and keyboard 16. This causes the circuit 26 to apply the jump pulses of the number corresponding to the difference between the current address and assignment address to the adder 13 which is connected to the circuit 12. Hence, the light spot is jumped by way of the optical parts 4, etc. of the head 100 by the output of the circuit 13, whereby the retrieval of the assigned track is accolplished within a short time. |
