OPTICAL MEASURING METHOD OF EXTREMELY SHORT DISTANCE

摘要

PURPOSE:To measure accurately the distance up to a body to be measured by using a light emitting and photodetecting element which has a light emitting element part for projecting light on the object body ad a photodetecting element part for photodetecting its reflected light as an extremely short-distance part. CONSTITUTION:Data on distance X corresponding to a ratio M (of photodetection output V and its maximum value Vp) is generated previously and the photodetection output Vp when the body to be measured is at distance from the sensor is measured in advance. A voltage is impressed between electrodes 29 and 33 by a power source 34 to drive the light emitting and photodetecting part 12, and a voltage is impressed between electrodes 32 and 33 by a power source 35. A photodetection output V is led out and the ratio M1=V/Vp of the photodetection output V and photodetction output Vp is calculated. Then, distance X1 corresponding to the M1 is calculated on the basis of the data. This distance X1 is therefore the distance from the sensor to the object body.