SHADOW DETECTION IN OPTICAL TOUCH SENSOR THROUGH THE LINEAR COMBINATION OF OPTICAL BEAMS AND GREY-SCALE DETERMINATION OF DETECTED SHADOW EDGES

• US 20080273019A1
• Filed: 05/02/2007
• Published: 11/06/2008
• Est. Priority Date: 05/02/2007
• Status: Active Grant

• Current Assignee: POA Sana Liquidating Trust
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Deane, Peter
• Granted Patent: US 7,809,221 B2
• Time in Patent Office: Days
• US Class Current: 345/176
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

An optical based input touch display device with high resolution shadow detection using the linear splitting of waveguides among transmit and receive lenses and grey-scale calculations for shadow edge and center detection is disclosed. The apparatus includes a light source and a transmit waveguide optically coupled to the light source. The transmit waveguide includes a plurality of transmit waveguide grooves coupled to a plurality of groups of shared transmit lenses respectively. The plurality of groups of transit lenses, which are configured to generate a plurality of collimated light beams from the light source. A receive waveguide is also provided having a plurality of receive waveguide grooves coupled to a plurality of groups of shared receive lenses. The plurality of groups of receive lenses are configured to receive the plurality of collimated light beams. A photodiode array including a plurality of photodiodes are optically coupled to the plurality of receive waveguide grooves respectively. Each of the photodiodes is configured to receive light from the plurality of light beams received by the plurality of groups of receive lenses respectively. A processor is configured to detect shadow edge and/or shadow center of an interrupt in the plurality of collimated light beams.

Claims

1. An apparatus, comprising;

a optical waveguide, the optical waveguide including;

a waveguide groove formed in the optical waveguide; and

a plurality of lenses optically coupled to the waveguide groove so that either light received by the plurality of lenses is combined in the waveguide groove or light transmitted by the waveguide groove is split among the plurality of lenses.

2. The apparatus of claim 1, wherein the combining and the splitting of the received or the transmitted light is linear among the plurality of lenses.

3. The apparatus of claim 1, wherein the combining and the splitting of the received or the transmitted light is non-linear among the plurality of lenses.

4. The apparatus of claim 1, wherein the plurality of lenses equals 2^N, where n ranges from one to six.

5. The apparatus of claim 1, wherein the plurality of lenses have an aperture ranging from 50 microns to 5 millimeters.

6. The apparatus of claim 1, wherein the waveguide is L-shaped and is configured to either receive or generate collimated light beams in the X and Y directions.

7. The apparatus of claim 1, further comprising a plurality of the waveguide grooves, each of the waveguide grooves having the plurality of lenses optically coupled thereto.

17. The apparatus of claim 1, wherein the optical waveguide is made from polymer and the waveguide groove is formed in the polymer.

18. The apparatus of claim 1, wherein the transmit waveguide and the receive waveguide are both polymer waveguides.

19. The apparatus of claim 1, wherein the optical waveguide is made from a piece molded substrate with the plurality of lenses and the waveguide groove molded into the substrate and an optically transparent material filling the waveguide groove.

8. An apparatus, comprising:

a light source;

a transmit waveguide optically coupled to the light source, the transmit waveguide having a plurality of transmit waveguide grooves coupled to a plurality of groups of shared transmit lenses respectively, the plurality of groups of transit lenses configured to generate a plurality of collimated light beams from the light source;

a receive waveguide having a plurality of receive waveguide grooves coupled to a plurality of groups of shared receive lenses, the plurality of groups of receive lenses being configured to receive the plurality of collimated light beams;

a photodiode array including a plurality of photodiodes optically coupled to the plurality of receive waveguide grooves respectively, each of the photodiodes configured to receive light from the plurality of light beams received by the plurality of groups of receive lenses respectively; and

a processor configured to detect shadow edge and/or shadow center of an interrupt in the plurality of collimated light beams.

9. The apparatus of claim 8, wherein the collimated light beams are transmitted and received in one or more of the following:

the X direction;

the Y direction;

or the X and Y directions.

10. The apparatus of claim 8, further comprising a touch screen of a data input device, wherein the collimated light beams are transmitted and received adjacent the touch screen device.

11. The apparatus of claim 8, wherein the plurality of shared groups of transmit lenses each comprises 2^N lenses where N ranges from one to six.

12. The apparatus of claim 8, wherein the plurality of shared groups of received lenses each comprises 2^N lenses where N ranges from one to six.

13. The apparatus of claim 8, wherein plurality of shared groups of transmit lenses have an aperture ranging from 50 microns to 5 millimeters.

14. The apparatus of claim 8, wherein plurality of shared groups of receive lenses have an aperture ranging from 50 microns to 5 millimeters.

15. The apparatus of claim 8, wherein the photodiodes generate voltage signals in proportion to the amount of the receive light from the plurality of light beams received by the plurality of groups of receive lenses respectively.

16. The apparatus of claim 15, wherein the processor detects the shadow edge and/or shadow center of an interrupt in the plurality of collimated light beams from the voltage signals in proportion to the amount of the receive light from the plurality of light beams received by the plurality of groups of receive lenses respectively.