TOUCH SCREEN SIGNAL PROCESSING

• US 20100090985A1
• Filed: 10/13/2009
• Published: 04/15/2010
• Est. Priority Date: 02/14/2003
• Status: Active Grant

• Current Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Next Holdings Ltd. (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Newton, John David
• Granted Patent: US 8,466,885 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

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.

Claims

1-88. -88. (canceled)

89. A touch detection system comprising:

a camera positioned to detect light representing a mirror image of the space above a touch surface; and

a processor configured to determine a position of an object relative to the touch surface based on the mirror image.

90. The touch detection system set forth in claim 89, wherein the determined position comprises a distance of the object from the touch surface.

91. The touch detection system set forth in claim 89, wherein the determined position comprises an indication of whether the object has touched the touch surface.

92. The touch detection system set forth in claim 91, wherein the camera is positioned to detect light representing an image of the object and the processor is configured to determine that the object has touched the touch surface when the image of the object and the mirror image of the object coincide.

93. The touch detection system set forth in claim 89, further comprising a second camera, and wherein the position comprises a coordinate indicating a position of the object in an area defined by the touch surface, the coordinate determined by triangulation using data from the cameras.

94. The touch detection system set forth in claim 89, wherein the touch surface comprises a screen configured for a user to view an object on or through.

95. The touch detection system set forth in claim 94, further comprising a light source, wherein the light source is positioned below the screen and light from the light source is directed through the screen.

96. A method, comprising:

imaging light using a detector, the light representing a mirror image of an object reflected by a touch surface; and

using a processor, determining a position of an object relative to the touch surface based on the mirror image.

97. The method set forth in claim 96, wherein the position comprises a distance of the object from the touch surface.

98. The method set forth in claim 96, wherein the position comprises an indication of whether the object has touched the touch surface.

99. The method set forth in claim 98, further comprising:

imaging light representing an image of the object.

100. The method set forth in claim 99, wherein the object is determined to have touched the touch surface if the image of the object and the mirror image of the object coincide.

101. The method set forth in claim 96, further comprising:

directing light from a light source through the touch surface.

102. The method set forth in claim 101, wherein the touch surface comprises a display screen.