DETECTING CIRCUIT

PROBLEM TO BE SOLVED: To solve such a problem that when an optical disk is reproduced and a recording region is detected, as a signal processing is performed after a signal outputted from the optical disk is passed through a transmission line of a flexible printed circuit board or the like, it is affected easily by noise, also, when the signal is transmitted in the transmission line as a differential signal to cancel an influence of the noise, the number of wiring of the circuit and the transmission line is increased. SOLUTION: Difference of a plurality of output signals from an optical pickup which is not generated as a differential signal is generated by a computing unit 14 after passing through a transmission line 13, this signal is binarized by a comparator 15, and presence of variation of the output is detected by a detector 16. As data exists in a recording region, binarized output is varied, but in a region being not yet recorded, as influence of noise is eliminated and output is not varied, the recording region can be detected. Thus, as a signal is not affected by noise in the transmission line, a recording region can be detected exactly and easily. COPYRIGHT: (C)2005,JPO&NCIPI