Patent ID: 6590201
Filing Date: 2003-07-08
Classification: G01D

Abstract:
An optical encoder comprising:an optical unit including a light emitter for emitting light and a light receiver for receiving the light from the light emitter; and a linear light controlling member including a plurality of transparent portions for passing the light from the light emitter and a plurality of nontransparent portions disposed alternately with the transparent portions for blocking the light from the light emitter, the transparent and the nontransparent portions being so arranged that any pair of adjacent transparent portion and nontransparent portion has a constant length longitudinally of the light controlling member, each transparent portion and each nontransparent portion being equal in length longitudinally of the light controlling member; the optical unit and the light controlling member being movable relative to each other longitudinally of the light controlling member; wherein the light receiver comprises a light receiver group including a plurality of light receiving elements arranged longitudinally of the light controlling member, each of the light receiving elements having a width longitudinally of the light controlling member, the width of each light receiving element being smaller than said constant length of the adjacent transparent portion and nontransparent portion; wherein the light receiver group has a length longitudinally of the light controlling member, the length of the light receiver group being different from said constant length of the adjacent transparent portion and nontransparent portion by an amount which is no less than the width of each light receiving element.