Patent ID: 7166833

Claim:
An optical encoder used to determine the position of a moving element, comprising: a code plate moving in concert with the moving element, the code plate provided with a plurality of encoder elements spanning at least a portion of said code plate, said encoder elements comprising a plurality of wedge-shaped elements, subdivided into a series of wedge-shaped elements, each series of wedge-shaped elements representing a digital word, wherein said code plate includes a plurality of representations of digital words, further wherein each of said digital words is subdivided into a plurality of digital bits, each of said digital bits comprising a number of parallel wedge-shaped elements spanning a portion of the width of said code plate constituting a single digital bit, the thickness of each of said wedge-shaped elements linearly changing over the length of each said digital bit; a stationary sensor head means facing the surface of said code plate; an optical emitter connected to said sensor head means for producing an optical beam directed at said plurality of encoder elements; an optical detector connected to said sensor head means for receiving an optical beam modulated by said encoder elements; and a signal processor for determining the position of said code plate with respect to said sensor head means based upon the optical beam modulated by said encoder elements; whereby the position of said code plate is related to the position of the moving element.