Optical touch device with pixilated light-turning features

Abstract

This disclosure provides systems, methods and apparatus for a touch screens configured to determine a position of a touch event by selectively redirecting light to correlated locations on a light sensor. In one aspect, the touch screen apparatus can include a light guide forming a touch interface, a light source for injecting light into the light guide, a light sensor for detecting the injected light, and a pixilated light-turning layer. The pixilated light-turning layer can include a plurality of light-turning features forming pixels. The pixels can receive incident light corresponding to the emitted light scattered by an object contacting the light guide. The pixels can redirect the incident scattered light towards the light sensor such that light selectively propagates to one or more correlated light receiving locations. A processor can map the light receiving location to an area contacted by the object, thereby determining a position of a touch event.

1 . (canceled) 
     
     
         2 . A touch screen apparatus comprising:
 a light source including a plurality of light emitters each configured to emit collimated light;   a light guide having:
 a major surface defining a touch input surface of the touch screen apparatus; and 
 a light input surface configured to receive light emitted by the plurality of light emitters; 
   a light sensor having a plurality of light receiving locations; and   a pixilated light-turning layer including a plurality of light-turning features forming pixels, each of the pixels configured to selectively redirect light emitted from the light source and scattered by an object above the touch input surface, wherein the scattered light is redirected to one or more correlated light receiving locations of the light sensor.   
     
     
         3 . The apparatus of  claim 2 , wherein the apparatus further comprises a processor configured to determine a coordinate corresponding to one axis of the major surface based on which light emitter of the plurality of light emitters emitted the collimated light into the light guide that was scattered by the object. 
     
     
         4 . The apparatus of  claim 2 , wherein the apparatus further comprises a processor configured to correlate a light receiving location receiving scattered light with a discrete area of the major surface. 
     
     
         5 . The apparatus of  claim 4 , wherein each discrete area on the major surface overlies one or more of the pixels, and wherein each of the one or more of the pixels is configured to redirect scattered light to a matching one of the one or more correlated light receiving locations. 
     
     
         6 . The apparatus of  claim 2 , wherein the plurality of light emitters are each configured to sequentially emit collimated light into the first edge of the light guide. 
     
     
         7 . The apparatus of  claim 6 , further comprising a processor configured to determine positions of the major surface simultaneously contacted by two different objects based at least partly on particular light receiving locations receiving scattered light associated with the two different objects and times at which the scattered light associated with the two different objects strike the particular light receiving locations. 
     
     
         8 . The apparatus of  claim 2 , further comprising a processor configured to determine positions of the major surface simultaneously contacted by two different objects based at least partly on particular light receiving locations receiving scattered light associated with the two different objects and wavelengths of the scattered light associated with the two different objects strike the particular light receiving locations. 
     
     
         9 . The apparatus of  claim 2 , wherein the light sensor is disposed on a second edge of the light guide, and wherein the second edge is disposed on an axis transverse to the first edge. 
     
     
         10 . The apparatus of  claim 9 , further comprising:
 a second plurality of light emitters configured to emit collimated light into a third edge of the light guide; and   a second light sensor disposed on a fourth edge of the light guide, wherein the fourth edge is disposed on an axis crossing the third edge.   
     
     
         11 . The apparatus of  claim 2 , wherein the light turning features are diffractive light turning features. 
     
     
         12 . The apparatus of  claim 2 , wherein the pixilated light-turning layer is a holographic layer, and wherein the light-turning features form holographic pixels. 
     
     
         13 . The apparatus of  claim 2 , wherein the light source is configured to emit infrared light. 
     
     
         14 . The apparatus of  claim 2 , wherein the light sensor is formed by an array of discrete light sensing devices. 
     
     
         15 . A touch screen apparatus comprising:
 a light guide having a major surface for receiving a touch input;   means for injecting collimated light into the light guide;   a light sensor having a light receiving surface, the light receiving surface having a plurality of light receiving locations; and   means for redirecting light injected into the light guide and scattered by an object contacting the major surface such that each of the plurality of light receiving locations selectively receives the scattered light substantially only from an area of the major surface correlated with the each of the plurality of light receiving locations.   
     
     
         16 . The apparatus of  claim 15 , wherein the light-turning means includes a plurality of light-turning features forming pixels, each pixel configured to selectively redirect light to a correlated light receiving location. 
     
     
         17 . The apparatus of  claim 15 , wherein the light-turning means is a holographic layer. 
     
     
         18 . The apparatus of  claim 15 , further comprising a processor configured to determine a coordinate corresponding to one axis of the major surface based at least partly on a time at which the light sensor receives the scattered light at a particular light receiving location of the plurality of light receiving locations. 
     
     
         19 . The apparatus of  claim 15 , further comprising a processor configured to determine positions of the major surface simultaneously contacted by two different objects. 
     
     
         20 . A method of detecting at least one touch event on a touch screen, the method comprising:
 receiving light directed from a pixilated light-turning layer at a light sensor location on a light sensor, the pixilated light-turning layer including pixels configured to redirect at least a portion of incident light scattered by an object above a light guide to the light sensor location;   mapping the light sensor location receiving the incident light with a location of the object, wherein the mapping includes determining which light source of a plurality of light sources emitted light into the light guide that was scattered by the object, and wherein the light sensor location is correlated with at least one pixel of the pixilated light-turning layer; and   determining a position of a touch event based at least partly on the mapping.   
     
     
         21 . The method of  claim 20 , wherein the pixilated light-turning layer is a holographic layer.