DETECTING TOUCH ON A SURFACE VIA A SCANNING LASER

• US 20090091553A1
• Filed: 10/03/2007
• Published: 04/09/2009
• Est. Priority Date: 10/03/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Lewis, John, Wilson, Andrew D., Keam, Nigel
• Granted Patent: US 8,184,101 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• 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 3/0423 using sweeping light beams, e.g. using rotating or vibrating mirror

Abstract

The detection of touch on an optical touch-sensitive device is disclosed. For example, one disclosed embodiment comprises a touch-sensitive device including a display screen, a laser, and a scanning mirror configured to scan light from the laser across the screen. The touch-sensitive device also includes a position-sensitive device and optics configured to form an image of at least a portion of the screen on the position-sensitive device. A location of an object relative to the screen may be determined by detecting a location on the position-sensitive device of laser light reflected by the object.

Claims

1. A touch-sensitive device, comprising:

a display;

a laser;

a scanning mirror configured to scan light from the laser across the display;

a position-sensitive device;

optics configured to form an image of at least a portion of the display on the position-sensitive device; and

a processor and memory containing instructions executable by the processor to determine a location of an object relative to the display by detecting via output from the position-sensitive device a location on the position-sensitive device of laser light reflected by the object.

2. The device of claim 1, wherein the instructions are executable to determine a location at which the object is touching the display.

3. The device of claim 1, wherein the instructions are executable to determine whether the object is spaced from the display.

4. The device of claim 1, wherein the instructions are executable to compare the location of the image of laser light detected with the position-sensitive device with an expected location of the image of laser light from the laser based upon a position of the scanning mirror.

5. The device of claim 1, further comprising a liquid crystal display panel disposed adjacent to the display for presenting an image to a user.

6. The device of claim 1, wherein the position-sensitive device is a one-dimensional position-sensitive device.

7. The device of claim 1, wherein the position-sensitive device is a two-dimensional position-sensitive device.

8. The device of claim 1, further comprising one or more photodetectors and instructions executable to record an image of the display via the one or more photodetectors.

9. The device of claim 1, further comprising a plurality of lasers and a plurality of position-sensitive devices configured to scan a plurality of portions of the display in parallel.

10. The device of claim 1, wherein the optics comprises one or more of a circular lens and a cylindrical lens.

11. The device of claim 1, further comprising an internal reflection device to transmit light from the laser to the display and to transmit reflected light from the object to the position-sensitive device.

12. In an optical touch-sensitive device comprising a display, a laser, a scanning mirror configured to scan light from the laser across the display, a position-sensitive device, and optics configured to form an image of the display on the position-sensitive device, a method of determining whether an object is touching the display or spaced from the display, the method comprising:

scanning the laser across the display with the scanning mirror;

detecting a location on the position-sensitive device of an image of laser light reflected from an object; and

determining a location of the object relative to the display by comparing the location of the image of laser light detected with the position-sensitive device with an expected location of the image of light from the laser based upon a position of the scanning mirror.

13. The method of claim 12, further comprising synchronizing the position-sensitive device and the scanning mirror by detecting on the position-sensitive device light reflected from one or more preselected calibration locations.

14. The method of claim 12, further comprising synchronizing the position-sensitive device and the scanning mirror by comparing a signal from the scanning mirror with a signal from the position-sensitive device.

15. The method of claim 12, further comprising determining a location of the object on the display.

16. The method of claim 12, further comprising determining whether the object is spaced from the display.

17. A method of operating an optical touch-sensitive device with an optical touch-sensitive display, the method comprising:

displaying an image viewable at the display;

scanning a laser across the display in two dimensions via a scanning mirror system;

acquiring an image of the display via one or more a photodetectors;

forming an image of the display on a position-sensitive device;

determining whether an object is touching the display or located over the display by comparing a location of reflected laser light in the image of the display with an expected location of reflected laser light based upon a position of the scanning mirror system; and

modifying the image displayed on the display based upon whether the object is touching the display or spaced from the display.

18. The method of claim 17, further comprising determining a location of the object on the display.

19. The method of claim 17, further comprising modifying the image if the object is spaced from the display.

20. The method of claim 17, further comprising modifying the image only if the object is touching the display.