Optical reflective encoder systems, devices and methods

Abstract

Disclosed are various embodiments of high-speed, high-performance, low-noise, low-cost, compact, optical encoders having a multi-faceted flat-faced lens disposed over the light emitters and light detectors thereof. Disclosed also are various means for preventing undesired stray light from reaching light detectors incorporated therein. Structures employed to block stray light in the optical encoders include light barriers, air gap trenches, and coatings disposed between first and second sides of a substrate of the encoder.

We claim: 
     
         1 . A reflective optical encoder, comprising:
 a top surface with opposing first and second sides, the top surface being substantially parallel to a horizontal plane;   a code scale disposed adjacent to the top surface;   a light emitter disposed on the first side of the top surface, and configured to emit light therefrom, the light emitter being configured to emit a substantial amount of light along a direction normal to the horizontal plane towards the code scale;   a light detector disposed on the second side of the top surface; and   a multi-faceted lens being integrally formed over the light emitter and the light detector such that no air gap is located between the light emitter and the lens, wherein the multi-faceted lens comprises a first face directly located over the light emitter, and a second face directly located over the light detector, and wherein the first and second faces are interconnected on one side and at least one of the first and second faces is tilted with respect to the horizontal plane,   wherein the code scale is located operably in respect of the multi-faceted lens such that at least a portion of the light reflected from the code scale is directed towards the second face and refracted through portions of the multi-faceted lens for detection by the light detector.   
     
     
         2 . The reflective optical encoder of  claim 1 , wherein the first face is substantially parallel to the horizontal plane and the second face is tilted with respect to the horizontal plane. 
     
     
         3 . The reflective optical encoder of  claim 1 , wherein the second face is substantially parallel to the horizontal plane and the first face is tilted with respect to the horizontal plane. 
     
     
         4 . The reflective optical encoder of  claim 1 , wherein the at least one of the first and second faces is tilted with respect to the horizontal plane at an angle that is selected such that efficiency of power delivery is maximized. 
     
     
         5 . The reflective optical encoder of  claim 1 , further comprising a light barrier disposed between the light emitter and the light detector, the light barrier being configured to prevent or inhibit stray light rays emitted by the light emitter from impinging upon the light detector. 
     
     
         6 . The reflective optical encoder of  claim 1 , wherein at least a portion of the first face or the second face is treated to prevent stray light rays from impinging upon the light detector. 
     
     
         7 . The reflective optical encoder of  claim 1 , wherein the lens comprises substantially flat surfaces including the first face and the second face, and is not spherically shaped lens surfaces. 
     
     
         8 . The reflective optical encoder of  claim 1 , wherein at least one of the first face and the second face comprises a diffractive optical element that changes directions of light rays transmitted to and from the code scale. 
     
     
         9 . The reflective optical encoder of  claim 8 , wherein the diffractive optical element of the at least one of the first face and the second face is configured to augment light directing functionality provided by the tilting of the at least one of the first face and the second face. 
     
     
         10 . The reflective optical encoder of  claim 8 , wherein the diffractive optical elements comprises thin phase elements that operate by at least one of interferences and diffraction. 
     
     
         11 . The reflective optical encoder of  claim 8 , wherein the first face comprises a first diffractive optical element and the second face comprises a second diffractive optical element. 
     
     
         12 . The reflective optical encoder of  claim 8 , wherein the code scale comprises data strips disposed between the light emitter and the light detector, wherein the data strips intersect a normal axis perpendicular to the horizontal plane, and the diffractive optical element is disposed on the first face approximating the light emitter but distanced away from the normal axis. 
     
     
         13 . The reflective optical encoder of  claim 8 , wherein the code scale comprises data strips disposed between the light emitter and the light detector, wherein the data strips intersect a normal axis perpendicular to the horizontal plane, and the diffractive optical element is disposed on the second face approximating the light detector but distanced away from the normal axis. 
     
     
         14 . An encoder system, comprising:
 an emitter configured to emit light;   a receiver configured to receive reflected light that is emitted from the emitter;   a substrate having a first surface extending along a first plane, wherein the emitter and the receiver are disposed on the first surface;   a code scale configured to receive the light from the emitter, wherein the code scale is configured to reflect a portion of the light back towards the receiver, the code scale intersecting a normal axis that is between the emitter and the receiver, the normal axis being substantially perpendicular to the first plane so as to divide the substrate to a first side having the emitter and a second side having the receiver;   a multi-faceted lens having a first face, a second face and a body, wherein the body is configured to cover the first surface of the substrate, the emitter, and the receiver, wherein the first face is located over the emitter on the first side such that the first face intercepts the light emitted from the emitter, wherein the second face is located over the receiver on the second side such that the second face intercepts the light reflected from the code scale; and   a first diffractive optical element disposed on at least one of the first face and the second face.   
     
     
         15 . The encoder system of  claim 14 , wherein at least one of the first face and the second face is tilted relative to the first plane. 
     
     
         16 . The encoder system of  claim 15 , wherein the first diffractive optical element is positioned on the at least one of the first face and the second face that is tilted relative to the first plane. 
     
     
         17 . The encoder system of  claim 16 , further comprising a second diffractive optical element disposed on the other of the at least one of the first face and the second face. 
     
     
         18 . The encoder system of  claim 14 , wherein the first face is positioned adjacent to the second face such that the first face has a side that is in direct contact with the second face and the normal axis extends through a portion of the side. 
     
     
         19 . The encoder system of  claim 14 , further comprising an air gap trench separating the first face and the second face, wherein the normal axis extends through a portion of the air gap trench. 
     
     
         20 . An optical encoder, comprising:
 an emitter configured to emit light;   a detector configured to receive light;   a first surface extending along a first plane to receive the emitter and the receiver;   a multi-faceted lens covering the emitter, the receiver and the first surface, the multi-faceted lens having a first lens face and a second lens face, the first lens face being located operably in respect of the emitter such that at least a portion of the light emitted by the emitter is intercepted by the first lens face, and the second lens face being located operably in respect of the detector such that a portion of the light reflected towards the detector is intercepted by the second lens face;   a first diffractive optical element disposed on the first lens face, the first diffractive optical element configured to intercept light emitted from the emitter;   a code scale having a data strip member configured to reflect a portion of light from the emitter towards the detector in accordance with a predetermined data pattern;   a second diffractive optical element disposed on the second lens face, the second diffractive optical element configured to intercept light reflected back from the data strip towards the detector; and   a light barrier disposed between the emitter and the detector on the first surface approximating the data strip of the code scale, the light barrier is configured to prevent light originating at the emitter from directly crossing over to the detector,   wherein at least one of the first lens face and the second lens face is tilted relative to each other causing the first and second diffractive optical elements to intercept light at different angles.