Patent ID: 6600146
Filing Date: 2003-07-29
Classification: G01S,G01V,H03K

Abstract:
A photoelectric switch comprising:a light emitting means for periodically emitting pulsed detection light; a light receiving means for photoelectrically converting said pulsed detection light and thereby outputting corresponding light detection signals; and a signal processing means for generating an on-off judgment output for switching on or off said photoelectric switch; said signal processing means including: a level shifting means for shifting the level of the light detection signals towards a specified level during a specified light receiving period by an amount corresponding to the difference between said specified level and the level of the light detection signal at a time immediately before said pulsed detection light is expected to arrive; and a condition judging means for judging, on the basis of the light detection signal with the level shifted by said level shifting means, whether or not at least one of conditions to be used for generating said on-off judgment output is satisfied; wherein said condition judging means serves to generate said on-off judgment output at least on the condition that the levels of the light detection signal at a first timing when a peak of the light detection signal is expected to arrive and at a second timing when a bottom of the light detection signal after an overshoot period is expected to arrive are in a specified size relationship.