Light-based touch screen

Abstract

A light-based touch screen, including a housing for a display screen, a plurality of infra-red light emitting diodes (LEDs), fastened on the housing, for generating light beams, at least one LED selector, fastened on the housing and connected with the plurality of LEDs, for controllably selecting and deselecting one or more of the plurality of LEDs, a plurality of photodiode (PD) receivers, fastened on the housing, for measuring light intensity, at least one PD selector, fastened on the housing and connected with the plurality of PD receivers, for controllably selecting and deselecting one or more of the plurality of PD receivers, an optical assembly, fastened on the housing, for projecting light beams emitted by the plurality of LEDs in substantially parallel planes over the housing, and a controller, fastened on the housing and coupled with the plurality of PD receivers, (i) for controlling the at least one LED selector, (ii) for controlling the at least one PD selector, and (iii) for determining therefrom position and velocity of an object crossing at least one of the substantially parallel planes, based on output currents of the plurality of PD receivers.

1 .- 20 . (canceled) 
     
     
         21 . A touch surface assembly for an electronic device, comprising:
 a surface that can be touched by an object from above;   a projector that projects light above said surface;   a barrier positioned in front of said projector, that blocks a portion of the light projected by said projector, thereby generating a light pattern;   a lens positioned in front of said projector and said barrier, that spreads the light pattern generated by said barrier, such that the object, when suitably positioned above the screen, reflects at least a portion of the light pattern spread by said lens; and   a camera aimed above said surface that captures one or more images of the light pattern spread by said lens and reflected by the object,   
       wherein a controller in communication with said camera determines location of the object relative to said surface by analyzing the one or more images captured by said camera. 
     
     
         22 . The touch surface assembly of  claim 21  wherein the controller identifies a gesture made by the object by analyzing the one or more images captured by said camera. 
     
     
         23 . The touch surface assembly of  claim 21  wherein said barrier comprises a metal plate with shapes etched thereon lithographically. 
     
     
         24 . The touch surface assembly of  claim 21  wherein said barrier comprises a grating. 
     
     
         25 . The touch surface assembly of  claim 21  wherein said projector is aimed above said surface at an angle of projection, and wherein said camera is aimed so as to be substantially aligned with said projector, so that said camera captures the one or more images at substantially the angle of projection. 
     
     
         26 . The touch surface assembly of  claim 21  wherein the location of the object relative to said surface identified by the controller, is a two-dimensional location. 
     
     
         27 . The touch surface assembly of  claim 21  wherein the location of the object relative to said surface identified by the controller, is a three-dimensional location. 
     
     
         28 . The touch surface assembly of  claim 21  wherein the controller also derives a location on said surface where the object is aimed, by analyzing the one or more images captured by said camera. 
     
     
         29 . The touch surface assembly of  claim 21  further comprising:
 at least one additional projector that projects light above said surface; 
 at least one additional barrier positioned in front of said respective at least one additional projector, that blocks a portion of the light projected by said respective at least one additional projector, thereby generating respective at least one additional light pattern; 
 at least one additional lens positioned in front of said respective at least one additional projector and said respective at least one additional barrier, that spreads the light pattern generated by said respective at least one additional barrier, such that the object, when suitably positioned above the screen, reflects at least a portion of the light pattern spread by said at least one additional lens; and 
 at least one respective additional camera in communication with said controller, aimed above said surface, that captures one or more images of the light pattern spread by said respective at least one additional lens and reflected by the object, wherein the controller determines the location of the object relative to said surface by analyzing the one or more images captured by each camera. 
 
     
     
         30 . The touch surface assembly of  claim 21  wherein the light pattern is a member of the group consisting of a pattern of digits, a pattern of letters, and a pattern of dots. 
     
     
         31 . The touch surface assembly of  claim 21  wherein the object is a member of the group consisting of a finger, a stylus and a pen. 
     
     
         32 . A method for operating a touch surface, comprising:
 projecting light above a surface, wherein the surface can be touched by an object from above;   blocking a portion of the light projected by said projecting, to generate a light pattern;   spreading the generated light pattern such that the object, when suitably positioned above the screen, reflects at least a portion of the light pattern spread by said lens;   capturing one or more images of the light pattern spread by said spreading and reflected by the object; and   analyzing the one or more images captured by said capturing, to determine location of the object relative to the surface.   
     
     
         33 . The method of  claim 32  comprising further analyzing the one or more images captured by said capturing, to identify a gesture made by the object. 
     
     
         34 . The method of  claim 32  wherein the location of the object relative to the surface identified by said analyzing, is a two-dimensional location. 
     
     
         35 . The method of  claim 32  wherein the location of the object relative to the surface identified by said analyzing, is a three-dimensional location. 
     
     
         36 . The method of  claim 32  comprising further analyzing the one or more images captured by said capturing to derive a location on said surface where the object is aimed. 
     
     
         37 . The method of  claim 32  wherein the light pattern is a member of the group consisting of a pattern of digits, a pattern of letters, and a pattern of dots. 
     
     
         38 . The method of  claim 32  wherein the object is a member of the group consisting of a finger, a stylus and a pen.