| 摘要 |
PURPOSE:To easily eliminate an offset component by providing a low pass filter to obtain a voltage corresponding to the extent of displacement of an objective lens and providing a feedback circuit which eliminates the DC offset component due to displacement of the objective lens. CONSTITUTION:A tracking error detecting circuit 1 consists of a two-divided photodetector and a differential amplifier, and a tracking error detection signal e(x) of the tracking error detecting circuit 1 is inputted to the + terminal of a subtractor 2. The subtractor 2 constitutes a feedback circuit 5 together with a low pass filter 3 and an amplifier 4, and this feedback circuit 5 has a function to eliminate the offset component included in the tracking error detection signal e(x).
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