Touch screen with light-enhancing layer

• US 7,394,058 B2
• Filed: 07/12/2006
• Issued: 07/01/2008
• Est. Priority Date: 07/12/2006
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Ravindaran, Kamala Manickavasagam, Chua, Janet Bee Yin, Lau, Yue Hoong
• Primary Examiner(s): MONBLEAU, DAVIENNE N
• Application Number:
  US11/484,908
• Publication Number:
  US 20080011944A1
• Time in Patent Office: 720 Days
• Field of Search: 250/221, 250/222.1, 250/227.11, 250/227.14, 385/12, 385/13, 345/173, 345/175, 345/176, 178/18.09, 178/18.11, 362/610, 362/615, 362/623
• US Class Current: 250/221
• CPC Class Codes: G02B 6/0035 provided on the surface of the light guide or in the bulk of it
• 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 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386

Abstract

A touch indication device comprises a light guide structure for passing light of a light source via total internal reflection. A touch surface disturbs the total internal reflection when touched, causing light to leave the light guide structure. A light enhancement layer converts the light leaving the light guide and sends the converted light to a light detector. The light enhancement layer amplifies the intensity and/or changes the color of the light leaving the light guide. The detector determines the position of the touch on the touch surface based on the light from the light enhancement layer.

Claims

1. A touch indication device comprising:

a light guide structure for passing light of a light source via total internal reflection;

a touch surface which disturbs the total internal reflection when touched, causing light to leave the light guide structure; and

a light enhancement layer for converting the light leaving the light guide and sending the converted light to a light detector wherein the light enhancement layer is comprised of phosphor and converts the color of the light leaving the light guide.

2. The device of claim 1, wherein the light enhancement layer amplifies the intensity of the light leaving the light guide.

3. The device of claim 1, wherein the thickness of the phosphor layer varies with position to output phosphor-converted light having position information.

4. The device of claim 1, wherein the composition of the phosphor layer varies with position to output phosphor-converted light having position information.

5. The device of claim 1, wherein the light detector comprises a color sensor.

6. The device of claim 1, wherein the light detector comprises a sensor array.

7. The device of claim 1, further comprising a CPU for receiving data from the detector and for controlling a display screen.

8. The device of claim 7, wherein the CPU generates and modifies simulated buttons and other objects as touch targets displayed on the display screen.

9. The device of claim 1, wherein the touch surface disturbs the total internal reflection when touched by a touch object which displaces the ambient air adjacent to the touch surface thereby reducing the difference in indices of refraction at the touch surface interface and disturbing the total internal reflection.

10. The device of claim 1, wherein the touch surface deforms the light guide inwardly when touched, causing an indentation in the light guide so that the light scatters from the indentation, thereby disturbing the total internal reflection.

11. The device of claim 9, wherein the light guide is made from ITO glass.

12. The device of claim 10, wherein the light guide is made from a deformable plastic.

13. The device of claim 1, wherein the light enhancement layer increases the efficiency of the light leaving the light guide.

14. The device of claim 1, wherein the light enhancement layer is located between the light guide and the light detector.