| 摘要 |
PURPOSE:To obtain an optical displacement converter which is hardly susceptible to the influence of a change in temp. by disposing a shielding plate displacing according to physical quantity between a light emission part and a photodetection part, changing periodically the light transmittance of the shielding plate and calculating the ratio of the output from the photodetection part. CONSTITUTION:A shielding plate 15 of a liquid crystal cell is connected through a switch 16 to a power source 17. The switch 16 is periodically turned on and off by the output of an oscillator 18, and the plate 15 is controlled nearly in a way as to open and close. The output of a photodetection part 12 is amplified with an amplifier 19 and the amplified output is changed over by a switch 21 in synchronization with the switch 16 and is drawn to terminals 22, 23. When the switch 16 turns on, the light transmittance of the plate 15 decreases and the output V1 in this stage and the output V2 when the switch 16 is off are divided by a circuit 24, by which an output V0(=V1/V2=(l+ or -x)/L2) is obtd. The output V0 is unaffected by the photoelectric conversion efficiency of the part 12 owing to the fluctuation in ambient temp. or deterioration with secular change and the fluctuation in the quantity of light of a light emission part 11. |
