| 摘要 |
PURPOSE:To always attain the highly accurate APC control for the quantity of emitted laser by eliminating the unbalance of weight that is caused per bit of the output value of a pin monitor by the difference of quantities of light emitted from a laser diode. CONSTITUTION:A varying circuit 7 varies the output gain with a/RD signal so as to secure the same weight per bit of the output value of a pin monitor 6 generated with the light quantity of a laser diode 5 that is decreased in a reproduction state and increased in a record/erasion state. At the same time, the circuit 7 amplifiers and outputs the input voltage received from a resistor R1 in accordance with the varied output gain. The circuit 7 consists of an operational amplifier 7a, received the negative feedback, a resistor R2, the feedback resistors R3 and R4 connected in parallel to each other, and an analog switch 7b which is connected in series to the R3 and turned on and off with the/RD signal. |
