Techniques for creating a virtual touchscreen

• US 8,446,389 B2
• Filed: 10/15/2008
• Issued: 05/21/2013
• Est. Priority Date: 10/15/2008
• Status: Active Grant

• Current Assignee: Lenovo PC International Limited (Lenovo Group Ltd.)
• Original Assignee: Lenovo Singapore Pte Limited (Lenovo Group Ltd.)
• Inventors: Challener, David C., Rutledge, James S., Yang, Jinping
• Primary Examiner(s): Bolotin, Dmitriy
• Application Number:
  US12/251,939
• Publication Number:
  US 20100090983A1
• Time in Patent Office: 1,679 Days
• Field of Search: 345/158, 345168-178, 178/18.04, 178/18.09, 178/18.11
• 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

A technique for creating a virtual touchscreen includes capturing, with a first infrared camera, a first reflection from an object that is at a known position adjacent a surface associated with a device. A second reflection from the object (at the known position) is captured with a second infrared camera. The first and second reflections are correlated with the known position to provide a two-dimensional position for the object that is calibrated with respect to the surface.

Claims

1. A method, comprising:

utilizing two infrared lasers to generate a plane of infrared light above a surface to transform said surface into a virtual touchscreen;

capturing, with a first infrared camera, a first group of infrared light reflected from an object breaking said plane of infrared light at a plurality of known positions on said surface, respectively, wherein said known positions correspond to a plurality of keys of a keyboard;

capturing, with a second infrared camera, a second group of infrared light reflected from said object breaking said plane of infrared light at said plurality of known positions on said surface, respectively; and

correlating said first and second groups of infrared light reflections and said plurality of known positions to provide a two-dimensional position for said object, wherein said two-dimensional position is calibrated with respect to said surface,

wherein said correlating further includes;

performing a first polynomial regression to determine a first set of coefficients for a first Taylor series expansion of a first coordinate of said two dimensional position; and

performing a second polynomial regression to determine a second set of coefficients for a second Taylor series expansion of a second coordinate of said two dimensional position.

2. The method of claim 1, wherein said two-dimensional position of said object is determined by solving

Xs=A3Xr³+A2Xr²+A1Xr+A0

Ys=B3Yr³+B2Yr²+B1Yr+B0

wherein Xs is an actual X surface position, Xr is a reflected X position as detected by said first infrared camera, Ys is an actual Y surface position, Yr is a reflected Y position as detected by said second infrared camera, wherein A0, A1, A2, A3, B0, B1, B2, and B3 are coefficients specific to physical dimensions of said virtual touchscreen.

3. The method of claim 1, wherein said first and second Taylor series expansions are third-order polynomials having four coefficients.

4. The method of claim 1, wherein said surface is associated with a screen of a device.

5. The method of claim 1, wherein said surface is associated with a keyboard of a device.

6. The method of claim 5, wherein said device is a computer.

7. The method of claim 1, wherein said object corresponds to a finger of a user.

8. The method of claim 7, wherein said device is a computer.

9. An apparatus, comprising:

two infrared lasers for generating a plane of infrared light above a surface to transform said surface into a virtual touchscreen;

two infrared cameras positioned to capture a first and second groups of infrared light reflected from an object breaking said plane of infrared light at a plurality of known positions on said surface, respectively, wherein said plurality of known positions correspond to a plurality of keys of a keyboard; and

a processor coupled to said two infrared cameras, wherein said processor is configured to correlate said first and second groups of infrared light reflections and said plurality of known positions to provide a two-dimensional position for said object that is calibrated with respect to said surface,

wherein said correlation includes

performing a first polynomial regression to determine a first set of coefficients for a first Taylor series expansion of a first coordinate of said two dimensional position; and

performing a second polynomial regression to determine a second set of coefficients for a second Taylor series expansion of a second coordinate of the two dimensional position.

10. The apparatus of claim 9, wherein said processor determines said position of said object by solving

Xs=A3Xr³+A2Xr²+A1Xr+A0

Ys=B3Yr³+B2Yr²+B1Yr+B0

wherein Xs is an actual X surface position, Xr is a reflected X position as detected by a first one of said infrared cameras, Ys is an actual Y surface position, Yr is a reflected Y position as detected by a second one of said infrared cameras, wherein A0, A1, A2, A3, B0, B1, B2, and B3 are constants specific to physical dimensions of said virtual touchscreen.

11. The apparatus of claim 9, wherein said first and second Taylor series expansions are third-order polynomials having four coefficients.

12. The apparatus of claim 9, wherein said apparatus is a computer.

13. A method, comprising:

decoding a plurality of keys of a keyboard of a device to provide a plurality of known positions for a surface associated with said device;

capturing, with infrared cameras, respective infrared light reflections from an object that is at said plurality of known positions; and

correlating said respective infrared light reflections and said plurality of known positions to provide a two-dimensional position for the object that is calibrated with respect to the surface by performing a first polynomial regression to determine a first set of coefficients for a first Taylor series expansion of a first coordinate of said two-dimensional position; and

by performing a second polynomial regression to determine a second set of coefficients for a second Taylor series expansion of a second coordinate of said two-dimensional position.