To provide an object detection sensor of an optical phase difference detection type for accurately detecting the existence of an object even when the light received by a light receiving element is excessively small or large.

This object detection sensor includes an amplitude average value calculating means 18a for measuring the amplitudes of light receiving signals 71c-77c for each first period and calculating average values AA1-AA7 related to the amplitude for each second period, a phase difference average value calculating means 18b for measuring the phase difference between light projection signals 50b-57b and light receiving signals 70b-77b for each first period and calculating average values PA1-PA7 related to the phase difference for each third period, and a determining means 18e for determining the existence of the object in the detection region when the difference between the amplitude average values AA1-AA7 and amplitude reference values AR1-AR7 is out of a first range and when this condition is not established and the difference between the phase difference average values PA1-PA7 and the phase difference reference values PR1-PR7 is out of a second range.

COPYRIGHT: (C)2009,JPO&INPIT