Correction of alignment and linearity errors in a stylus input system

• US 6,727,896 B2
• Filed: 08/01/2001
• Issued: 04/27/2004
• Est. Priority Date: 08/01/2001
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Tsang, Michael H.
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): FATAHI YAR, MAHMOUD
• Application Number:
  US09/918,482
• Publication Number:
  US 20030025680A1
• Time in Patent Office: 1,000 Days
• Field of Search: 345/178, 345/173, 178/18.01, 178/18.02, 178/18.03, 178/18.04, 178/18.05, 178/18.06, 178/19.01
• US Class Current: 345/178
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A method and system for correcting alignment and linearity errors in devices using a finger or stylus input device with a display device interactively coupled to a digitizer is disclosed. Touching intersections in a calibration grid on the display device may be performed to create a linearity map. Subsequently, detected stylus input is mapped to a sector in the linearity map, and resultant screen coordinates are calculated using ratios within a reference rectangle corresponding to the detected stylus input and the mapped sector.

Claims

1. A method for correcting input errors in a data processing system using a stylus input device and a digitizer, comprising the steps of:

(i) detecting an input point;

(ii) determining a sector of a linearity map in which the detected input point is located, wherein the linearity map comprises a non-linear array of points, each point comprising a predetermined screen point and a corresponding detected calibration point;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based at least in part on the reference rectangle and the linearity map.

2. The method of claim 1, wherein the array comprises a two-dimensional array.

3. The method of claim 1, wherein the digitizer comprises an RF digitizer.

4. The method of claim 1, wherein the digitizer comprises a resistive digitizer.

8. The method of claim 1, wherein the linearity map is created during a manufacturing process.

5. A method for correcting input errors in a data processing system using a stylus input device and a digitizer, comprising the steps of:

(i) detecting an input point;

(ii) determining a sector of a linearity map in which the detected input point is located;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based at least in part on the reference rectangle and the linearity map,

wherein step (ii) comprises the steps of;

(a) maximizing the area of each sector to be a rectangle bounding the sector; and

(b) selecting any sector in whose bounding rectangle the detected point is located.

6. A method for correcting input errors in a data processing system using a stylus input device and a digitizer, comprising the steps of:

(i) detecting an input point;

(ii) determining a sector of a linearity map in which the detected input point is located;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based at least in part on the reference rectangle and the linearity map,

wherein step (iii) comprises the steps of;

(a) determining a first vertical intersection point of the detected point'"'"'s y-axis with a sector boundary;

(b) determining a second vertical intersection point of the detected point'"'"'s y-axis with a sector boundary;

(c) determining a first horizontal intersection point of the detected point'"'"'s x-axis with a sector boundary;

(d) determining a second horizontal intersection point of the detected point'"'"'s x-axis with a sector boundary; and

(e) forming a rectangle wherein each side of the rectangle contains an intersection point.

7. A method for correcting input errors in a data processing system using a stylus input device and a digitizer, comprising the steps of:

(i) detecting an input point;

(ii) determining a sector of a linearity map in which the detected input point is located;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based at least in part on the reference rectangle and the linearity map,

wherein step (iv) comprises the steps of;

(a) determining a first ratio of the distance of the detected point'"'"'s X-coordinate from a vertical side of the reference rectangle to a width of the reference rectangle;

(b) calculating the screen point'"'"'s X-coordinate so that the ratio of the distance of the screen'"'"'s point'"'"'s X-coordinate from a first corresponding side of a screen rectangle is the same as the first ratio;

(c) determining a second ratio of the distance of the detected point'"'"'s Y-coordinate from a horizontal side of the reference rectangle to a height of the reference rectangle; and

(d) calculating the screen point'"'"'s Y-coordinate so that the ratio of the distance of the screen'"'"'s point'"'"'s Y-coordinate from a second corresponding side of the screen rectangle is the same as the second ratio.

9. A data processing system comprising:

a digitizer for detecting user input from a user using a stylus input device;

a display screen coupled to the digitizer;

a processor; and

a memory storing computer readable instructions that, when executed by the processor, cause the data processing system to perform the steps of;

(i) detecting an input point on the digitizer from the stylus input device;

(ii) determining a sector of a linearity map in which the detected input point is located, wherein the linearity map comprises a non-linear array of points, each point comprising a predetermined screen point and a corresponding detected calibration point;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based on the reference rectangle and the linearity map.

10. The system of claim 9, wherein the array comprises a two-dimensional array.

11. The system of claim 9, wherein the digitizer comprises an RF digitizer.

12. The system of claim 9, wherein the digitizer comprises a resistive digitizer.

13. A data processing system comprising:

a digitizer for detecting input from a user using a stylus input device;

a display screen coupled to the digitizer;

a processor; and

a memory storing computer readable instructions that, when executed by the processor, cause the data processing system to perform the steps of;

(i) detecting an input point on the digitizer from the stylus input device;

(ii) determining a sector of a linearity map in which the detected input point is located;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based on the reference rectangle and the linearity map,

wherein step (ii) comprises the steps of;

(a) maximizing the area of each sector to be a rectangle bounding the sector; and

(b) selecting any sector in whose bounding rectangle the detected point is located.

14. A data processing system comprising:

a digitizer for detecting input from a user using a stylus input device;

a display screen coupled to the digitizer;

a processor; and

a memory storing computer readable instructions that, when executed by the processor, cause the data processing system to perform the steps of;

(i) detecting an input point on the digitizer from the stylus input device;

(ii) determining a sector of a linearity map in which the detected input point is located;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based on the reference rectangle and the linearity map,

wherein step (iii) comprises the steps of;

(a) determining a first vertical intersection point of the detected point'"'"'s y-axis with a sector boundary;

(b) determining a second vertical intersection point of the detected point'"'"'s y-axis with a sector boundary;

(c) determining a first horizontal intersection point of the detected point'"'"'s x-axis with a sector boundary;

(d) determining a second horizontal intersection point of the detected point'"'"'s x-axis with a sector boundary; and

(e) forming a rectangle wherein each side of the rectangle contains at least one intersection point.

15. A data processing system comprising:

a digitizer for detecting input from a user using a stylus input device;

a display screen coupled to the digitizer;

a processor; and

a memory storing computer readable instructions that, when executed by the processor, cause the data processing system to perform the steps of;

(i) detecting an input point on the digitizer from the stylus input device;

(ii) determining a sector of a linearity map in which the detected input point is located;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based on the reference rectangle and the linearity map,

wherein step (iv) comprises the steps of;

(a) determining a first ratio of the distance of the detected point'"'"'s X-coordinate from a vertical side of the reference rectangle to a width of the reference rectangle;

(b) calculating the screen point'"'"'s X-coordinate so that the ratio of the distance of the screen'"'"'s point'"'"'s X-coordinate from a first corresponding side of a screen rectangle is the same as the first ratio;

(c) determining a second ratio of the distance of the detected point'"'"'s Y-coordinate from a horizontal side of the reference rectangle to a height of the reference rectangle; and

(d) calculating the screen point'"'"'s Y-coordinate so that the ratio of the distance of the screen'"'"'s point'"'"'s Y-coordinate from a second corresponding side of the screen rectangle is the same as the second ratio.

16. A computer readable medium storing computer readable instructions that, when executed by a processor, cause a data processing device to perform the steps of:

(i) detecting an input point on a digitizer;

(ii) determining a sector of a linearity map in which the detected input point is located, wherein the linearity map comprises a non-linear array of points, each point comprising a predetermined screen point and a corresponding detected calibration point;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based at least in part on the reference rectangle and the linearity map.

17. The computer readable medium of claim 16, wherein the array comprises a two-dimensional array.

18. The computer readable medium of claim 16, wherein the digitizer comprises an RF digitizer.

19. The computer readable medium of claim 16, wherein the digitizer comprises a resistive digitizer.

23. The computer readable medium of claim 16, wherein the linearity map is created during a manufacturing process.

20. A computer readable medium storing computer readable instructions that, when executed by a processor, cause a data processing device to perform the steps of:

(i) detecting an input point on a digitizer;

(ii) determining a sector of a linearity map in which the detected input point is located;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based at least in part on the reference rectangle and the linearity map,

wherein step (ii) comprises the steps of;

(a) maximizing the area of each sector to be a rectangle bounding the sector; and

(b) selecting any sector in whose bounding rectangle the detected point is located.

21. A computer readable medium storing computer readable instructions that, when executed by a processor, cause a data processing device to perform the steps of:

(i) detecting an input point on a digitizer;

(ii) determining a sector of a linearity map in which the detected input point is located;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based at least in part on the reference rectangle and the linearity map,

wherein step (iii) comprises the steps of;

(a) determining a first vertical intersection point of the detected point'"'"'s y-axis with a sector boundary;

(b) determining a second vertical intersection point of the detected point'"'"'s y-axis with a sector boundary;

(c) determining a first horizontal intersection point of the detected point'"'"'s x-axis with a sector boundary;

(d) determining a second horizontal intersection point of the detected point'"'"'s x-axis with a sector boundary; and

(e) forming a rectangle wherein each side of the rectangle contains an intersection point.

22. A computer readable medium storing computer readable instructions that, when executed by a processor, cause a data processing device to perform the steps of:

(i) detecting an input point on a digitizer;

(ii) determining a sector of a linearity map in which the detected input point is located;

(iii) calculating a reference rectangle based on the detected point; and

(iv) calculating a screen point corresponding to the input point based at least in part on the reference rectangle and the linearity map,

wherein step (iv) comprises the steps of;

(a) determining a first ratio of the distance of the detected point'"'"'s X-coordinate from a vertical side of the reference rectangle to a width of the reference rectangle;

(b) calculating the screen point'"'"'s X-coordinate so that the ratio of the distance of the screen'"'"'s point'"'"'s X-coordinate from a first corresponding side of a screen rectangle is the same as the first ratio;

(c) determining a second ratio of the distance of the detected point'"'"'s Y-coordinate from a horizontal side of the reference rectangle to a height of the reference rectangle; and

(d) calculating the screen point'"'"'s Y-coordinate so that the ratio of the distance of the screen'"'"'s point'"'"'s Y-coordinate from a second corresponding side of the screen rectangle is the same as the second ratio.