Optical encoder with at least one lenticular sheet

Abstract

An optical encoder comprising a light source (12) emitting a light beam, a first lenticular array (14) to which the light beam is directed, a second movable lenticular array (16) to which the light beam exiting from the first lenticular array is directed and a light receiving element (18). The individual lenslets in the first and the second lenticular array refract the light beam into fine beams of periodic pattern or dark and bright fringes. As the movable lenticular array is being displaced in a direction parallel to the first lenticular array, the incident angle of the light beam exiting from the first lenticular array to the second lenticular array is changed, which results in a change in the position of the periodic pattern. Thus, as the position of the periodic pattern is changing, the output of the light receiving element varies accordingly and may readily be converted to a digital signal indicative of the position and direction of the movable lenticular array.

Description

technical field [0001] The present invention relates to an optical encoder for measuring displacement of a moving part, such as a shaft angle optical encoder or a position sensor. Background technique [0002] Various optical encoders are known for determining the position and motion of an object. figure 1 An optical encoder disclosed in German Patent Application (DE A1) No. 2,316,248 is exemplified. The optical encoder includes a light source 200, a lens 202 for collimating the light beam emitted from the light source 200, a first fixed diffraction grating 204 and a second movable diffraction grating 206, a condenser lens 208, and light receivers 210, 212 and 214 . The light source 200 is collimated and irradiated onto the first fixed diffraction grating 204 and then irradiated onto the second movable diffraction grating 206 . When the movable diffraction grating 206 moves in the direction indicated by arrow R, the interference fringes move on the light receiving element...

AI Technical Summary

Problems solved by technology

[0004] Although this prior art works well depending on the measuring device and the required accuracy, optical encoders using diffractive gratings provide higher resolution than code wheels, but are also more expensive to manufacture and more complex to design

However, the resolution of a low-cost, simple code wheel cannot meet the requirements of some devices because there is an upper limit to the number of apertures in the code wheel.

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