Touch screen signal processing

Abstract

A touch screen which uses light sources at one or more edges of the screen which directs light across the surface of the screen and at least two cameras having electronic outputs located at the periphery of the screen to receive light from said light sources. A processor receives the outputs of said cameras and employs triangulation techniques to determine the location of an object proximate to said screen. Detecting the presence of an object includes detecting at the cameras the presence or absence of direct light due to the object, using a screen surface as a mirror and detecting at the cameras the presence or absence of reflected light due to an object. The light sources may be modulated to provide a frequency band in the output of the cameras.

1 .- 30 . (canceled) 
   
   
       31 . A touch display comprising:
 a screen for a user to touch and view an image on or through;   light sources at one or more edges of said screen, said light sources directing light across the surface of said screen;   a lighting controller configured to control the operation of sections of said light sources independent of other sections of said light sources;   at least two cameras having outputs, each said camera located at the periphery of said screen to image the space in front of said screen, said output including a scanned image;   means for processing said outputs to detect the level of light, said light including:
 direct light from said light sources, and/or 
 reflected light from said light sources; 
   a processor receiving the processed outputs of said cameras, said processor employing triangulation techniques and said processed outputs to determine whether the processed outputs indicate the presence of an object proximate to said screen and if so the location of said object.   
   
   
       32 . A touch display as claimed in  claim 31  wherein said processed output indicates the relative bearing of a presumed object location relative to said camera and the distance of said object from said screen. 
   
   
       33 . A touch display as claimed in  claim 31  wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera. 
   
   
       34 . A touch display as claimed in  claim 31  wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide. 
   
   
       35 . A touch display as claimed in  claim 31  wherein said cameras are line scan cameras, said camera output including information on line scanned and said processor using said information in determining the location of said object. 
   
   
       36 . A touch display as claimed in  claim 31  wherein said processor determines the location of said object as a planar screen co-ordinate. 
   
   
       37 . A touch display as claimed in  claim 31  wherein said light sources are behind said screen arranged to project light through said screen and said display includes at each edge having a light source, light deflectors in front of said screen, directing light emitted from said light sources across the surface of said screen. 
   
   
       38 . A touch display as claimed in  claim 31  wherein said light sources are Light Emitting Diodes (LEDs). 
   
   
       39 . A touch display as claimed in  38  wherein the lighting controller is configured to independently control the effective intensity of said light source. 
   
   
       40 . A touch display as claimed in  claim 38  wherein the sections of said light source are wired in antiphase and the lighting controller comprises a bridge drive driving the sections. 
   
   
       41 . A touch display as claimed in  claim 38  wherein the lighting controller comprises a diagonal bridge drive. 
   
   
       42 . A touch display as claimed in  claim 38  wherein lighting controller comprises a shift register. 
   
   
       43 . A touch display as claimed in  claim 38  wherein said means for taking and processing images includes controlling sections of said light sources and each said camera and said means for processing said outputs includes processing information on whether a said section is lighted or not. 
   
   
       44 . A touch display as claimed in  claim 43  wherein some sections are lighted and others are not when an image is taken. 
   
   
       45 - 53 . (canceled) 
   
   
       54 . A method of receiving user inputs in reference to an image including the steps of:
 providing a screen for a user to touch and view an image on or through;   providing light sources at one or more edges behind said screen, said light sources directing light across the surface of said screen;   controlling the operation of sections of said light sources independent of other sections of said light sources;   providing at least two cameras having outputs, each said camera located at the periphery of said screen to image the space in front of said screen, said output including a scanned image;   processing said outputs to detect the level of light, said light including:
 direct light from said light sources, and/or 
 reflected light from said light sources; 
   processing the processed outputs of said cameras, using triangulation techniques to obtain the location of said object.   
   
   
       55 . A method of receiving user inputs in reference to an image as claimed in  claim 54  wherein said processed output indicates the relative bearing of a presumed object location relative to a said camera. 
   
   
       56 . A method of receiving user inputs in reference to an image as claimed in  claim 54  wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera. 
   
   
       57 . A method of receiving user inputs in reference to an image as claimed in  claim 54  wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide. 
   
   
       58 . A method of receiving user inputs in reference to an image as claimed in  claim 54  wherein said cameras are line scan cameras, said camera output including information on line scanned and said processor using said information in determining location of said object. 
   
   
       59 . A method of receiving user inputs in reference to an image as claimed in  claim 54  wherein said location is a planar screen co-ordinate. 
   
   
       60 . A method of receiving user inputs in reference to an image as claimed in  claim 54  wherein said light sources are behind said screen and arranged to project light through said screen and said display includes at each edge having a light source, light deflectors in front of said screen, directing light emitted from said light sources across the surface of said screen. 
   
   
       61 . A method of receiving user inputs in reference to an image as claimed in  claim 54  wherein said light sources are LEDs and said touch display includes means for controlling the operation of sections of said light source independent of other sections of said light source. 
   
   
       62 . A method of receiving user inputs in reference to an image as claimed in  claim 61  wherein the step of controlling the operation of sections of said light source includes independently controlling the effective intensity of said light source. 
   
   
       63 . A method of receiving user inputs in reference to an image as claimed in  claim 61  wherein the step of controlling sections of said light source comprises wiring said sections in antiphase and driving using a bridge drive. 
   
   
       64 . A method of receiving user inputs in reference to an image as claimed in  claim 61  wherein the step of controlling sections of said light source comprises using a diagonal bridge drive. 
   
   
       65 . A method of receiving user inputs in reference to an image as claimed in  claim 61  wherein the step of controlling sections of said light source comprises using a shift register for each section to be controlled. 
   
   
       66 . A method of receiving user inputs in reference to an image as claimed in  claim 61  wherein the step of taking and processing images includes controlling sections of said light sources and each said camera and said step of processing said outputs includes processing information on whether a said section is lighted or not. 
   
   
       67 . A method of receiving user inputs in reference to an image as claimed in  claim 66  wherein some sections are lighted and others are not when an image is taken. 
   
   
       68 - 88 . (canceled)