Integrated touch-sensing display apparatus and method of operating the same

Abstract

An integrated touch-sensing display is operated to detect the location of one or more objects on a touch surface. The integrated touch-sensing display defines a display area. A light guide ( 14 ) is arranged over the display area to define the touch surface ( 16 ). The light guide ( 14 ) is illuminated internally such that an object ( 20 ) contacting the touch surface ( 16 ) causes part of the illuminating light to be scattered towards the display area. An array of light sensors ( 6 ) is integrated within the display area to detect the scattered light. Based on output signals from the light sensors ( 6 ), a processing element obtains image data that represents the light that impinges on the display area excluding ambient light, and determines the location of the object ( 20 ) on the touch surface ( 16 ). Ambient light may he suppressed by a spectral passband filter in front of each light sensor ( 6 ), and/or by electronic filtering of the output signals from the sensors ( 6 ). The light guide ( 14 ) may be illuminated by invisible light, and may be arranged to cause an illuminating beam to be internally reflected at a peripheral edge surface of the light guide ( 14 ), so as to increase the intensity of illuminating light inside the light guide ( 14 ).

1 - 33 . (canceled) 
     
     
         34 . An integrated touch-sensing display apparatus, comprising:
 an array of picture elements that defines a display area;   an array of light-sensing elements integrated within the display area;   a light guide located in front of the display area to define a touch surface, the light guide being configured to allow light to propagate inside the light guide by total internal reflection;   a light source arrangement for providing illuminating light inside the light guide, such that an object contacting the touch surface causes frustration of the total internal reflection of the illuminating light and thereby part of the illuminating light to be scattered towards the display area;   a processing element configured to obtain image data representing the scattered illuminating light impinging on the display area based on output signals from the light-sensing elements and independent of signal patterns resulting from ambient light and light scattered by non-touching objects, the processing element being further configured to determine the location of the object on the touch surface based on the image data; and   a filter arrangement for suppressing said ambient light.   
     
     
         35 . The integrated touch-sensing display apparatus of  claim 34 , wherein the light source arrangement is configured to modulate the illuminating light at a predetermined modulation frequency, and wherein the filter arrangement comprises a circuit for lock-in detection at the modulation frequency, which circuit operates on the output signals from the light-sensing elements. 
     
     
         36 . The integrated touch-sensing display apparatus of  claim 34 , wherein the light source arrangement is configured to modulate the illuminating light at a predetermined modulation frequency, and wherein the filter arrangement comprises at least one bandpass filter operating on the output signals from the light-sensing elements to remove frequencies outside a passband around the modulation frequency. 
     
     
         37 . The integrated touch-sensing display apparatus of  claim 36 , wherein the at least one bandpass filter comprises an analog filter circuit. 
     
     
         38 . The integrated touch-sensing display apparatus of  claim 36 , wherein the array of light-sensing elements and the at least one bandpass filter are integrated on a common substrate. 
     
     
         39 . The integrated touch-sensing display apparatus of  claim 35 , wherein the modulation frequency is at least about 0.5 kHz. 
     
     
         40 . The integrated touch-sensing display apparatus of  claim 34 , wherein the light source arrangement is configured to provide the illuminating light in a confined wavelength region, and wherein the filter arrangement comprises at least one spectral passband filter which is arranged in front of the light-sensing elements so as to suppress the ambient light in relation to the illuminating light. 
     
     
         41 . The integrated touch-sensing display apparatus of  claim 34 , wherein the illuminating light is invisible to the human eye. 
     
     
         42 . The integrated touch-sensing display apparatus of  claim 41 , wherein the illuminating light is in a wavelength region above 700 nm. 
     
     
         43 . A method of operating an integrated touch-sensing display apparatus, which apparatus comprises an array of picture elements that defines a display area; an array of light-sensing elements integrated to sense light within the display area; a light guide located in front of the display area to define a touch surface; and a light source arrangement, said method comprising:
 controlling said at least one light source arrangement to provide illuminating light inside the light guide, such that an object contacting the touch surface causes part of the illuminating light to be scattered towards the display area;   obtaining, based on output signals from the light-sensing elements, image data that represents the light that impinges on the display area excluding ambient light, and   determining, based on the image data, the location of the object on the touch surface.   
     
     
         44 . The method of  claim 43 , further comprising controlling the light source arrangement to modulate the illuminating light at a predetermined modulation frequency, and operating a circuit for lock-in detection at the modulation frequency on the output signals from the light-sensing elements. 
     
     
         45 . The method of  claim 43 , further comprising controlling the light source arrangement to modulate the illuminating light at a predetermined modulation frequency, and obtaining the image data from at least one bandpass filter which operates on the output signals from the light-sensing elements to remove frequencies outside a passband around the modulation frequency. 
     
     
         46 . The method of  claim 43 , further comprising operating the light source arrangement to provide the illuminating light in a confined wavelength region, wherein at least one wavelength filter is arranged in front of the light-sensing elements so as to suppress the ambient light in relation to the illuminating light. 
     
     
         47 . A non-transitory computer-readable medium comprising program instructions which, when executed by a processor, cause the processor to perform the method of  claim 43 .