OPTICAL ENCODER READ HEAD CONFIGURED TO BLOCK STRAY LIGHT

摘要

PROBLEM TO BE SOLVED: To provide an optical read head for preventing stray rays of light from entering into a circuit element.;SOLUTION: An optical read head for measuring displacement along a measurement axial direction of a read head and a scale track includes: an illumination part configured to output light source rays of light to the scale track; and a monolithic detector structure. The monolithic detector structure includes: a first track light detector part configured to receive scale rays of light from the scale track; a first metallic layer; a second metallic layer; and a plurality of dummy vias 371 formed between the first metallic layer and the second metallic layer. The plurality of dummy vias 371 are arranged to block transmission of rays of light passing through a layer between the first metallic layer and the second metallic layer, and the plurality of dummy vias 371 are formed in a process same as a process of manufacturing a plurality of valid vias for connecting the circuit elements on the monolithic detector structure.;COPYRIGHT: (C)2013,JPO&INPIT