Signal detection system of optical information reproducing device

Abstract

Abstract PURPOSE: To detect a tracking signal having high accuracy, by photodetecting reflected rays from a disk by a prescribed 4 split detector, and sampling a difference of sum signals at a zero-crossing point of rise or fall of the sum of sum signals of the detectors which have been arranged in the diagonal direction. CONSTITUTION: Reflected rays from a disk is detected by a 4 detector 41W44 which have been split in the tracking direction and the direction meeting at right angles with said direction. The sum of outputs, S 5 =S 1 +S 3 and S 6 =S 2 +S 4 , of the detectors 41, 43 and 42, 44 which have been arranged in the diagonal direction are derived by summing circuits 45, 46. Also, the sum of those outputs, S 7 =S 5 +S 6 is derived by a summing circuit 47, and the difference, S 8 =S 5 -S 6 is derived by a difference circuit 48. A zero-crossing point of rise and fall is detected by rise and fall pulse generating circuits 49, 50, and S 8 is sampled through gate circuits 51, 52 by its signals S 25 , S 26 , and its output is outputted 56 as a tracking signal S 29 through holding circuit 53, 54 and a differential amplifier 55. In this way, the tracking signal S 29 having high accuracy is detected. COPYRIGHT: (C)1982,JPO&Japio

Inventors

• 👤 Tsutomu Shibata

Bibliographic Details