Method and apparatus for calibrating targets on a touchscreen

• US 20080150909A1
• Filed: 12/11/2007
• Published: 06/26/2008
• Est. Priority Date: 12/11/2006
• Status: Active Grant

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Elo Touch Solutions, Inc.
• Inventors: North, Kenneth J., Bahr, Jeffery L., Kent, Joel C.
• Granted Patent: US 8,164,582 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment

Abstract

A method for using a touch display system comprises defining local distortion zones within regions of a touchscreen. Each of the local distortion zones has an associated calibration touch point and a target. Coordinates of a user touch point are distorted within a first local distortion zone based on a location of the user touch point within the first local distortion zone.

Claims

1. A method for using a touch display system, comprising:

defining local distortion zones within regions of a touchscreen, each of the local distortion zones having an associated calibration touch point and a target; and

distorting coordinates of a user touch point within a first local distortion zone based on a location of the user touch point within the first local distortion zone.

2. The method of claim 1, wherein the local distortion zones comprise one of a circle, an ellipse, a diamond shape, square, rectangle, triangle.

3. The method of claim 1, further comprising:

determining an overlap distortion zone comprising coordinates of the touchscreen which are within the first local distortion zone and a second local distortion zone; and

distorting coordinates of a second user touch point within the overlap distortion zone based on a location of the second user touch point with respect to first and second calibration touch points that are associated with first and second local distortion zones, respectively.

4. The method of claim 1, further comprising:

determining a first discrepancy vector between a first calibration touch point and a first target;

computing a weighting factor based on the user touch point; and

computing an amount of the first discrepancy vector based on the weighting factor, the amount being applied to distort the coordinates of the user touch point.

5. The method of claim 1, further comprising computing a first discrepancy vector between a first calibration touch point and a first target, the first discrepancy vector representing a maximum local distortion offset that may be applied to the user touch point.

6. The method of claim 1, further comprising:

defining an overlap distortion zone comprising overlapping portions of first and second local distortion zones associated with first and second calibration touch points, respectively;

determining a first displacement between a second user touch point within the overlap distortion zone and the first calibration touch point and a second displacement between the second user touch point and the second calibration touch point; and

minimizing a local distortion offset associated with the second calibration touch point when the second user touch point is closer to the first calibration touch point.

7. A touchscreen system comprising:

a display screen;

a touchscreen being mounted to the display screen; and

a local distortion module being configured to;

compute a first discrepancy vector based on a first target displayed on the display screen and a first calibration touch point detected on the touchscreen;

compute a first local distortion zone comprising the first calibration touch point, the first local distortion zone comprising a first portion of the touchscreen; and

distort coordinates of user touch points detected within the first local distortion zone based on the first distortion vector.

8. The system of claim 7, the local distortion module further configured to distort the coordinates of a first user touch point within the first local distortion zone by a portion of the first distortion vector, the portion being based on a proximity of the first user touch point to a first calibration touch point.

9. The system of claim 7, the local distortion module further configured to:

compute a weighting factor based on a displacement from a user touch point to the first calibration touch point; and

compute locally distorted coordinates for the user touch point based at least on the weighting factor.

10. The system of claim 7, the local distortion module further configured to:

compute a second discrepancy vector based on a second calibration touch point and a second target;

compute a second local distortion zone comprising the second calibration touch point, the first and second local distortion zones forming an overlap zone of common touchscreen coordinates; and

applying a weighting factor to each of the first and second discrepancy vectors when a second user touch point is within the overlap zone.

11. The system of claim 7, further comprising a linearity correction module configured to apply a linearity calibration process to correct the first calibration touch point, the first local distortion zone being based on the corrected first calibration touch point.

12. The system of claim 7, the local distortion module further configured to compute a weighting factor to scale the first discrepancy vector of the first target based on at least a first discrepancy from the first calibration touch point, the weighting factor being zero when the user touch point is outside the first local distortion zone.

13. The method of claim 7, further comprising a linearity correction module applying a linearity calibration process to correct coordinates of the user touch points, the corrected coordinates being distorted by the local distortion module.

14. A method for calibrating a touch display system, comprising:

detecting a first calibration touch point on a touchscreen associated with a first target displayed on a display screen, the first calibration touch point and the first target having first and second sets of coordinates, respectively;

defining a first local distortion zone based on the first calibration touch point, the first local distortion zone comprising an area of the touchscreen including at least the first calibration touch point; and

determining a first discrepancy vector for distorting coordinates of a user touch point within the first local distortion zone, the first discrepancy vector being based on the first set of coordinates and the second set of coordinates.

15. The method of claim 14, further comprising adjusting the first set of coordinates based on results of a linearity calibration process of the touchscreen.

16. The method of claim 14, wherein the first target is displayed on the display screen corresponding to at least one of a corner and a perimeter of the touchscreen.

17. The method of claim 14, further comprising:

detecting a second calibration touch point on the touchscreen associated with a second target displayed on the display screen, the second calibration touch point and the second target having third and fourth sets of coordinates;

defining a second local distortion zone based on the second calibration touch point, the second local distortion zone comprising an area of the touchscreen including at least the second calibration touch point; and

determining an overlap region wherein the first and second local distortion zones comprise like coordinates.

18. The method of claim 14, further comprising applying a linearity correction to the first calibration touch point to form a corrected first calibration touch point, the first local distortion zone being based on the corrected first calibration touch point.