High performance reflective optical encoder

Abstract

An optical encoder includes an emitter, a first lens, a detector, a second lens, and a protrusion. The emitter emits light which is directed by the first lens to a code scale for reflection. The reflected light is directed by the second lens to the detector. The detector detects the reflected light from the code scale. The protrusion is between the first lens and the second lens. The protrusion defines at least one surface that refracts stray light from the emitter away from the detector. Accordingly, the stray light does not reach the detector; thus the detector can operate more effectively.

Description

technical field [0001] The present invention generally relates to optical encoders. More particularly, the present invention relates to improved optical encoders having higher contrast ratios than prior art encoders. Background technique [0002] Optical encoders detect motion and are often used to provide closed-loop feedback to motor control systems. When working in conjunction with a codescale, an optical encoder detects motion (linear or rotational motion of the codescale) and converts the detected motion into a digital signal that encodes the motion, position or velocity of the codescale. Here, the term "code stick" includes code discs and code tapes. [0003] Typically, the movement of the yardstick is optically detected by optical emitters and optical detectors. The optical emitter emits light that impinges on and reflects off the yardstick. A typical yardstick consists of a regular pattern of grooves and stripes that reflect light in a known pattern. Light is re...

AI Technical Summary

Problems solved by technology

Such stray light 119 is undesirable because stray light reaching the detector 102 can introduce false signals, reducing the resolution of the analysis of the desired signal

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