OPTICAL DISK REPRODUCING DEVICE AND METHOD FOR ADJUSTING GAIN OF TRACKING SERVO LOOP

摘要

PURPOSE: To stably reproduce by suppressing the fluctuation in the gain of a tracking servo loop by providing a signal process device adjusting the gain of the tracking servo loop based on a phase difference between two pieces of sub-beams measured by a phase difference measurement means ;CONSTITUTION: The data read out from an optical disk 7 by a main beam M are transmitted to a matrix amplifier 31 through a main beam M signal line 3a. The amplifier 31 forms a data signal (A+B+C+D) adding all of signals (A to D) inputted through four pieces of signal lines 3a and a focus error signal (A+C)-(B+D). The focus error signal is fed back to a focus coil 3 through the amplifier 32. The data signal is compared with a reference signal in a comparison circuit 42 to become a tracking error signal. On the other hand, the signal obtained by two pieces of subbeams is inputted to a subtracter 24 through a sub-beam E signal line 2a and a sub-beam F signal line 2b and the amplifiers 22, 23 to be subtracted, and it forms a tracking signal of E-F, and controls a gain adjustment circuit 25.;COPYRIGHT: (C)1995,JPO