| 摘要 |
PURPOSE:To accurately record and reproduce information always by executing compensation operation for the offset of an amplifier or the dark current of an optical source in the deadlock period or the standstill period of an optical recording medium. CONSTITUTION:A period signal indicating the first standstill period and the deadlock period at a turning point in the reciprocating motion of the optical information recording medium is generated by a specified circuit. A switch SW1 provided on a light beam source 1 is on or off in accordance with the period signal. Thus, a light beam generating means is off and when the dark current exists, the current flows to the extent of the dark current then the compensation operation for the dark current is executed. Also, a holding circuit H is connected with the amplifier OA1 by turning a switch SW2 on and when the offset owing to temperature changing or the like exists, the offset value is stored and amplifying operation taking the offset value into account is executed at next time. |
