Patent ID: 6026246
Filing Date: 2000-02-15
Classification: G02B

Abstract:
A distance measuring apparatus comprising:light-emitting means for outputting a light beam toward an object to be subjected to distance measurement;light-receiving means for receiving reflected light of the light beam projected on said object at a light-receiving position corresponding to a distance to said object and outputting, on the basis of the light-receiving position, a far-side signal whose value becomes larger when the distance increases if an amount of received light remains the same and a near-side signal whose value becomes larger when the distance decreases if the amount of received light remains the same;clamp means for receiving the far-side signal, comparing a level of the far-side signal with that of a clamp signal, and directly outputting the far-side signal when the far-side signal has a level higher than that of the clamp signal, and otherwise, outputting the clamp signal;arithmetic means for calculating an output ratio of the near-side signal to the signal output from said clamp means and outputting an output ratio signal; andconversion means for converting the output ratio signal into a distance signal corresponding to the distance in accordance with a transformation formula which changes depending on whether the output ratio signal is on a far side of a predetermined reference level, the predetermined reference level being a clamp effect presence/absence determination reference level defined by a reference object reflectivity.