| 摘要 |
<P>PROBLEM TO BE SOLVED: To keep the amplitude of an RF signal outputted from a light receiver constant regardless of a distance between a light transmitter and the light receiver. <P>SOLUTION: The light receiver has a photo detector 15 converting an input optical signal Pin into an electric signal and outputting the electric signal to a preamplifier 20 and a detecting section 30, the detecting section 30 detecting only the DC component Ip of the output electric signal, a variable-light attenuator driving section 25 preparing a control signal Iin corresponding to the intensity of the Ip detected by the detecting section 30, and a variable-light attenuator 10 attenuating an optical signal inputted from an optical fiber 5 in response to the intensity of the control signal Iin. The variable-light attenuator 10 largely attenuates the optical signal when the control signal Iin is large, and attenutes small the optical signal when the control signal Iin is small. <P>COPYRIGHT: (C)2004,JPO |
