| 摘要 |
PROBLEM TO BE SOLVED: To prevent a light receiving unit from being unstable owing to excess light received by a light receiving element. SOLUTION: A first stage amplifier circuit 12 is connected to the light receiving element, that is, a photodiode 11 via a capacitor 20. An output stage of the first stage amplifier circuit 12 comprises a PNP transistor 24, and an output of the output stage transistor 24 is given to a base of an output transistor 25 for controlling an output of the first stage amplifier circuit 12. The output transistor 25 acts also like an optical axis selection means, and when the output transistor 25 receives a selection signal from an optical axis selection circuit 17, the output transistor 25 outputs a light receiving signal amplified by the first stage amplifier circuit 12 to a signal processing circuit (clamp circuit). The collector of the output stage PNP transistor 24 is connected to GND via a resistor 26. COPYRIGHT: (C)2004,JPO&NCIPI |
