Light guide touch screen

• US 20070084989A1
• Filed: 09/14/2004
• Published: 04/19/2007
• Est. Priority Date: 09/22/2003
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Schoellmann, Volker, Lange, Ruediger
• Application Number:
  US10/572,624
• Publication Number:
  US 20070084989A1
• Time in Patent Office: Days
• US Class Current: 250/221
• CPC Class Codes: G02B 6/0011 the light guides being planar or of plate-like form
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

The present invention relates to a display device with a detection system for detecting an input po- sition on a screen (301) of the display. A light guide (302) is arranged adjacent to the screen (301). The light guide (302) has a light source (308) arranged to emit light (310) into the light guide (302). The optical matching between the light guide (302) and its surroundings is adapted such that the light (310) of the light source (308) is normally confined within the light guide (302) by means of total internal reflection. However, a user establishing physi- cal contact with the light guide (302) perturbs the state of total internal reflection, and light (310) will be extracted from the light guide (302). In the display device, light detecting means (303) are arranged to detect said light (310) and relate this detection to an input position where the user contact occurred. The display is preferably an LCD, O-LED or P-LED type display.

Claims

1. A display device, including a display, arranged for detecting an input position on a screen (301) of said display,

wherein the screen (301) comprises a light guide (302) and a light source (308) arranged to emit light (310) into the light guide (302), the light guide (302) being optically matched with its surroundings in such way that the light (310) emitted from said light source (308) is confined within the light guide (302) by means of total internal reflection, and is extracted from the light guide (302) when a user establishes physical contact with said screen (301) at said input position,

the display device further comprising a light detecting means (303) for detecting the light extracted from the light guide (302) and relate the detecting of said extracted light to said input position.

2. A display device as claimed in claim 1, wherein the light detecting means comprises a plurality of photo sensors or photo detectors associated with different input positions on the screen (301) of the display.

3. A display device as claimed in claim 1, wherein the light detecting means (303) is integrated with a substrate of the display.

4. A display device as claimed in claim 3, wherein the display is an active matrix type display (301).

5. A display device as claimed in claim 4, wherein the substrate is provided with thin film transistors (510) associated with picture elements of the display screen (301), the light detecting means (303) including said thin film transistors (510).

6. A display device as claimed in claim 1, wherein the light guide (302) is optically matched with the screen (301).

7. A display device as claimed in claim 1, wherein the light guide (402) is integrated with a front plate of the display device.

8. A display device as claimed in claim 1, wherein the light source (308) arranged to emit light into the light guide (302) emits light in the infrared range.

9. A display device as claimed in claim 1, wherein the light detecting means (303) are provided with an optical filter to increase the selectivity for light extracted from the light guide (302).