Drift compensated optical touch screen

• US 8,502,803 B2
• Filed: 07/26/2009
• Issued: 08/06/2013
• Est. Priority Date: 04/07/2009
• Status: Expired due to Fees

• Current Assignee: Lumio Incorporated
• Original Assignee: Lumio Incorporated
• Inventors: Lieberman, Klony, Maor, Yaniv, Gunders, Dan
• Primary Examiner(s): Lao, Lun-Yi
• Assistant Examiner(s): Suteerawongsa, Jarurat
• Application Number:
  US12/509,467
• Publication Number:
  US 20100253637A1
• Time in Patent Office: 1,472 Days
• Field of Search: 345/156, 345/173, 345175-179, 178/18.09, 178/18.11, 178/19.01, 178/19.05
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

An optical touch screen including a display surface, an optical illumination assembly arranged along at least part of a periphery of the display surface, at least one light detector arranged to detect light distribution produced by the optical illumination assembly and changes in the light distribution produced by the presence of an object in predetermined propinquity to the display surface, detection circuitry receiving at least one output from the at least one light detector and providing an output indication of a two-dimensional location of the object relative to the display surface, calibration functionality responsive to changes in light distribution other than changes produced by the presence of an object in predetermined propinquity to a region of the display surface for calibrating the detection circuitry, at least one auxiliary illumination source, and at least one partially transmissive, partially reflective optical element disposed along a light path to the at least one light detector, providing a light transmissive optical path for light to the at least one light detector and a light reflective optical path for light from the at least one auxiliary illumination source.

Claims

1. An optical touch screen comprising:

a generally planar display surface;

an optical illumination assembly arranged generally along at least part of a periphery of said generally planar display surface;

at least one light detector arranged to detect light distribution produced by said optical illumination assembly and changes in said light distribution produced by the presence of an object in predetermined propinquity to a region of said generally planar display surface;

detection circuitry receiving at least one output from said at least one light detector and providing an output indication of a two-dimensional location of said object relative to said generally planar display surface; and

calibration functionality responsive to changes in said light distribution other than changes produced by the presence of an object in predetermined propinquity to a region of said generally planar display surface for calibrating said detection circuitry so as to compensate for changes in an angular field of view of said light detector,

said calibration functionality being responsive to temperature induced changes in said light distribution which result at least in part from temperature induced changes in a focal length of at least one optical element in said at least one light detector and cause changes in the angular field of view of said light detector.

2. An optical touch screen according to claim 1 and wherein said calibration functionality calibrates an output of said detection circuitry which represents said two-dimensional location of said object relative to said generally planar display surface.

3. An optical touch screen according to claim 1 and wherein said changes in light distribution other than changes produced by the presence of an object in predetermined propinquity to a region of said generally planar display surface comprise shifts in apparent positions of peaks of light sources in said optical illumination assembly.