| 摘要 |
PURPOSE:To make the device small in size, light in weight and low in cost and facilitate signal processing by sending the repetitive pulse light signals differing in phase by 90 deg. from a pair of light emitting elements to a traget surface and detecting the phase deviation of the irregularly reflected light via a photodetector provided at the intermediate of both light emitting elements. CONSTITUTION:A pair of light emitting diodes 1, 2 of GaAs or the like and one phototransistor 4 are disposed opposedly to a target 5 at a fixed space. The square wave pulse light signals differing in phase by 90 deg. are outputted from the light emitting diodes 1 and 2 via an oscillator 10 and a phase shifter 11, and the irregularly reflected light from the surface P of the target 5 is detected with the phototransistor 4. The outputs thereof are sent to a multiplier 22 via an amplifier 12, a band-pass filter 13, an AGC 14, and a rectangular wave converting circuit 21, by which the phase difference is determined from the product of the pulse signal from the oscillator 10, and the distance of the surface P is displayed in a display device 30. There- by, the device is made small in size, light in weight and low in cost and the signal processing is made easy. |
