| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a preamplifier which is not to be saturated by servo signals caused by reflected light beams that are reflected from an optical disk during recording. <P>SOLUTION: Reflected light beams from the optical disk are received by a photodetector 21. A photoelectric converted output current of the photodetector 21 is supplied to one of the input terminals of an operational amplifier 22. A switch 23 is provided between a current bias circuit 30 and the input terminal of the operational amplifier 22. Writing gate signals are varied during an information recording and an information reproducing. The switch 23 is controlled so that a bias current is supplied to the input terminal during recording, and during reproducing the bias current is turned off. <P>COPYRIGHT: (C)2003,JPO |
