Position detector.

摘要

A position detector includes a light emitting component (5a,5a') for irradiating the surface (4a) of an object (4) whose position is to be measured. Two light receiving components (5b,5b') receive light reflected by the surface, a distance from one of the light receiving components to the measured surface as viewed in a direction substantially perpendicular to the surface being different from a distance from the other of the light receiving components to the surface. A calculating circuit (6) calculates a correction quantity for correcting the distances between the light receiving components and the surface, with the correction quantity being calculated on the basis of a difference between the output signals of the light receiving components. A moving component (12) corrects the distances between the measured surface and the light receiving components in accordance with the correction quantity. A first embodiment has two light receiving components (5b,5b') spaced at different distances from the surface. A second embodiment (Figs 8 and 9) has two light receiving components (5b,5b') disposed between two light emitting components (5a,5a') or two light emitting components disposed between two light receiving components. A third embodiment (Figs. 12 and 13) has two light receiving components (9b,9c) spaced the same distance from the surface, but at different distances from light emitting components (9a). <IMAGE>