Patent ID: 7639374
Filing Date: 2009-12-29
Classification: G01B,G01S

Abstract:
1. An optical displacement sensor comprising: a light projection device for directing projected light to a target object; a light reception device for receiving light reflected by said target object from the projected light; an amount-of-displacement calculation means for determining a one-dimensional position of a received-light spot on the light reception device, on the basis of the output of said light reception device, and calculating a amount of displacement of said target object, on the basis of the one-dimensional position of the received-light spot determined; a difference-value creation means for sampling the amount of displacement calculated by said amount-of-displacement calculation means by a constant time interval, and determining a value of a difference between a current value representing the amount of displacement sampled at a current timing and a previous value representing the amount of displacement sampled at a previous timing prior to the current timing as a difference value; a difference-value comparison means for making a comparison of the difference value determined by said difference-value creation means with two threshold values including a positive threshold value and a negative threshold value; and an object detection means for determining the presence or absence of said target object on the basis of the result of the comparison made by said difference-value comparison means, and outputting a detection signal indicative of the result of the determination of the presence or absence of said target object; wherein said object detection means turns on the detection signal on the basis of the result of the comparison of the difference value with one of the two threshold values, and turns off the detection signal on the basis of the result of the comparison of the difference value with the other of the two threshold values.