Touchscreen display calibration using results history

• US 6,809,726 B2
• Filed: 06/04/2001
• Issued: 10/26/2004
• Est. Priority Date: 12/11/2000
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Kavanagh, David A.
• Primary Examiner(s): Liang, Regina
• Assistant Examiner(s): Nguyen, Jennifer T.
• Application Number:
  US09/871,880
• Publication Number:
  US 20020070926A1
• Time in Patent Office: 1,240 Days
• Field of Search: 345/173, 345/174, 345/175, 345/176, 345/177, 345/156, 345/178, 345/157, 345/179, 178/18.01, 178/18.02, 178/18.03, 178/18.09
• 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 calibration of touchscreen display coordinates includes displaying a calibration target; sensing a calibration touch for the calibration target; obtaining a calibration touchpoint coordinate for the calibration touch; determining if the calibration touchpoint coordinate is valid; and if so, storing the calibration touchpoint coordinate in a touchpoint history database and using calibration touchpoint coordinates to define a calibration reference point for operation, otherwise generating a computed reference calibration point as an average of using a predetermined number of the calibration touchpoint coordinates in the touchpoint history database.

Claims

1. A method for calibration of touchscreen display coordinates by an operator comprising:

(a) displaying at least one calibration target, the calibration target corresponding to a calibration reference point;

(b) sensing a calibration touch for the at least one calibration target;

(c) obtaining a calibration touchpoint coordinate for the calibration touch;

(d) determining if the calibration touchpoint coordinate is valid by comparing the calibration touchpoint coordinate to a coordinate boundary defined by selected valid calibration touchpoint coordinates for the calibration target stored in a touchpoint history database comprising a plurality of valid calibration touchpoint coordinates obtained from sensed calibration touches for the calibration target; and

(e) if so, storing the calibration touchpoint coordinate in the touchpoint history database and using the calibration touchpoint coordinate to define a calibration reference point for operation, otherwise generating a computed reference calibration point using a predetermined number of the plurality of valid calibration touchpoint coordinates stored in the touchpoint history database.

2. The method according to claim 1, wherein step (e) generates the computed reference calibration point as an average of a predetermined number of the calibration touchpoint coordinates in the touchpoint history database.

3. The method according to claim 2, wherein the computed reference calibration point is generated using a weighted average of a predetermined number of the calibration touchpoint coordinates in the touchpoint history database.

4. The method according to claim 2, wherein step (d) compares the calibration touchpoint coordinate to a standard deviation of the selected calibration touchpoint coordinates defining the coordinate boundary.

5. The method according to claim 1, wherein the coordinate boundary is defined by a statistical metric of the selected calibration touchpoint coordinates in the touchpoint history database.

6. A method for calibration of touchscreen display coordinates, comprising:

(a) maintaining a touchpoint calibration history comprising a plurality of touchpoint coordinates obtained from calibration touches for a calibration target;

(b) receiving a calibration touchpoint coordinate corresponding to the calibration target;

(c) determining if the calibration touchpoint coordinate is valid by comparing the calibration touchpoint coordinate to a coordinate range defined by selected calibration touchpoint coordinates from the touchpoint calibration history; and

(d) if the calibration touchpoint coordinate is not valid providing a computed reference calibration point based on the touchpoint calibration history.

7. The method of claim 6, wherein the touchpoint calibration history comprises a list of valid calibration touchpoint coordinates and step (d) provides the computed reference calibration point by computing an average of a predetermined number of the calibration touchpoint coordinates in the touchpoint calibration history.

8. The method according to claim 7, wherein step (d) provides the computed reference calibration point by computing a weighted average of a predetermined number of the calibration touchpoint coordinates in the touchpoint calibration history.

9. The method according to claim 6, wherein the touchpoint calibration history comprises a list of valid calibration touchpoint coordinates and wherein step (c) compares the calibration touchpoint coordinates to a coordinate range defined by a statistical metric of the selected calibration touchpoint coordinates from the touchpoint calibration history.

10. The method according to claim 6, wherein the touchpoint calibration history comprises a list of valid calibration touchpoint coordinates and wherein step (c) compares the calibration touchpoint coordinates to a coordinate range defined by a standard deviation of the selected calibration touchpoint coordinates from the touchpoint calibration history.

11. The method according to claim 6, wherein the touchpoint calibration history comprises the computed reference calibration point and step (a) maintains the touchpoint calibration history by generating a recomputed reference calibration point using the computed reference calibration point and a calibration touchpoint coordinate.