| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a light emission reception device capable of switching gains with a simple configuration without providing a dedicated terminal for gain switching. <P>SOLUTION: The light emission reception device is provided with a semiconductor laser 8, a first photodiode 1 for receiving return light that is returned when forward light emitted from the semiconductor laser 8 is reflected by an optical disk, a second photodiode 11 for receiving backward light emitted from the semiconductor laser 8, and an amplifier circuit for converting a current signal generated by the first photodiode 1 into a voltage signal and amplifying the voltage signal. The amplifier circuit is provided with an operational amplifier 2, a first gain resistor 3 and a second gain resistor 4 connected in parallel with the operational amplifier 2, and a switching circuit 7 for switching the gain resistors, wherein switching between the first gain resistor 3 and the second gain resistor 4 is performed on the basis of a signal from the second photodiode 11. <P>COPYRIGHT: (C)2007,JPO&INPIT |
