| 摘要 |
<p>By an output signal from a four-divided detector (2a, 2b, 2c, 2d), arithmetic is done on a tracking error signal TE, a focuserror signal FE, and on a total light amount signal Y. The signals are submitted to time division multiplexing, and are entered as a reference voltage of a D/A converter(7). As a digital input of the D/A converter (7), supplied is data DB from a reciprocal table (12). The DB is a reciprocal of the data DA which is a digitalized total light amount signal Y. In the D/A converter (7), the error signal and data DB are multiplied together so as to generate an error signal of which amplitude is constant against variation in laser power. By the error signal, a servo drive signal is generated in a signal processing circuit (9). <IMAGE></p> |
