| 摘要 |
PROBLEM TO BE SOLVED: To decide infinity accurately by obtaining a distance signal from an output ratio signal according to a conversion formula dependent on the presence of clamp operation, the brightness of external light, and the like, thereby determining the distance to an object accurately in a short time using a small scale of circuit regardless of fluctuation in the brightness of external light. SOLUTION: A distal signal I2 outputted from a PSD (position detecting element) 5 receiving a reflected light from an object is inputted through a second signal processing circuit 12 to a clamp circuit 13 which outputs a signal I2c, i.e., any one of the distal signal I2 or a constant level clamp signal Ic having higher level. An operating circuit 14 and an integrating circuit 15 receiving a proximal signal I1 from the PSD 5 and the signal I2c from the clamp circuit 13, respectively, determine the output ratio (I1/(I1+I2c)). A CPU 1 determines a distance signal from the output ratio according to a first conversion formula when the clamp is not operating and according to a second conversion formula having an INFDATA dependent on the brightness of external light, and the like, during clamp operation. |
