CAPACITIVE TOUCH SENSOR AND CAPACITIVE PEN

• US 20130155016A1
• Filed: 12/17/2012
• Published: 06/20/2013
• Est. Priority Date: 12/19/2011
• Status: Active Grant

• Current Assignee: eGalax_eMPIA Technology Inc.
• Original Assignee: eGalax_eMPIA Technology Inc.
• Inventors: CHANG, CHIN-FU, YEH, SHANG-TAI, CHIU, SHIH-HAO
• Granted Patent: US 10,007,361 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0441 using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures

Abstract

When a touch sensor is approached or touched by an object having a small area, the corresponding approach or touch signal might be slightly less than the threshold originally used for normal detection. By comparing the sum of the corresponding approach or touch signal and some adjacent signals with the threshold, the approach or touch of a small-area object that otherwise would not be detected by the original method can be determined.

Claims

1. A method for detecting an approach or a touch of a small area, comprising:

obtaining an image of change in capacitive coupling from a capacitive touch sensor, wherein the capacitive touch sensor includes a plurality of driven conductive strips driven by a driving signal and a plurality of sensed conductive strips providing changes in capacitive coupling, each time the driving signal is provided, one or more intersections between one or more of the conductive strips being simultaneously driven by the driving signal and each sensed conductive strip generate capacitive coupling, and each value in the image of change in capacitive coupling is the change in capacitive coupling for one of the intersections;

detecting each detected intersection from the image of change in capacitive coupling, wherein the value of the detected intersection is smaller than a first threshold and larger than a second threshold;

detecting each first region, wherein each first region includes one of the detected intersections and an intersection adjacent to the detected intersection, and the sum of values of the first region is greater than the first threshold;

detecting each second region if no first region is detected, wherein each second region includes four adjacent intersections including one of the detected intersections, and the sum of values of the second region is greater than the first threshold; and

determining a first region or a second region approached or touched by an external conductive object when at least one first region or at least one second region is detected, wherein the values of all intersections adjacent to the first region or the second region approached or touched by the external conductive object are all smaller than a third threshold.

2. The method of claim 1, wherein the first threshold>

the second threshold>

the third threshold.

3. The method of claim 1, wherein the second threshold is ½

of the first threshold, and the third threshold is ¼

of the first threshold.

4. The method of claim 1, wherein the maximum width of the approach or touch of a small area by an external conductive object is less than the distance between the centers of two conductive strips arranged adjacent and in parallel with each other, the two conductive strips arranged adjacent and in parallel with each other are the driven conductive strips or the sensed conductive strips.

5. The method of claim 1, wherein each first region or second region determined to be approached or touched by an external conductive object is a first region or a second region approached or touched by a pen, wherein the maximum width on the touch sensor touched by the pen is less than or equal to 3 mm.

6. A device for detecting an approach or a touch of a small area, comprising:

a means for obtaining an image of change in capacitive coupling from a capacitive touch sensor, wherein the capacitive touch sensor includes a plurality of driven conductive strips driven by a driving signal and a plurality of sensed conductive strips providing changes in capacitive coupling, each time the driving signal is provided, one or more intersections between one or more of the conductive strips being simultaneously driven by the driving signal and each sensed conductive strip generate capacitive coupling, and each value in the image of change in capacitive coupling is the change in capacitive coupling for one of the intersections;

a means for detecting each detected intersection from the image of change in capacitive coupling, wherein the value of the detected intersection is smaller than a first threshold and larger than a second threshold;

a means for detecting each first region, wherein each first region includes one of the detected intersections and an intersection adjacent to the detected intersection, and the sum of values of the first region is greater than the first threshold;

a means for detecting each second region if no first region is detected, wherein each second region includes four adjacent intersections including one of the detected intersections, and the sum of values of the second region is greater than the first threshold; and

a means for determining a first region or a second region approached or touched by an external conductive object when at least one first region or at least one second region is detected, wherein the values of all intersections adjacent to the first region or the second region approached or touched by the external conductive object are all smaller than a third threshold.

7. The device of claim 6, wherein the first threshold>

the second threshold>

the third threshold.

8. The device of claim 6, wherein the second threshold is ½

of the first threshold, and the third threshold is ¼

of the first threshold.

9. The device of claim 6, wherein the maximum width of the approach or touch of a small area by an external conductive object is less than the distance between the centers of two conductive strips arranged adjacent and in parallel with each other, the two conductive strips arranged adjacent and in parallel with each other are the driven conductive strips or the sensed conductive strips.

10. The device of claim 6, wherein each first region or second region determined to be approached or touched by an external conductive object is a first region or a second region approached or touched by a pen, wherein the maximum width on the touch sensor touched by the pen is less than or equal to 3 mm.

11. A method for detecting an approach or a touch of a small area, comprising:

obtaining an image of change in capacitive coupling from a capacitive touch sensor, wherein the capacitive touch sensor includes a plurality of driven conductive strips driven by a driving signal and a plurality of sensed conductive strips providing changes in capacitive coupling, each time the driving signal is provided, one or more intersections between one or more of the conductive strips being simultaneously driven by the driving signal and each sensed conductive strip generate capacitive coupling, and each value in the image of change in capacitive coupling is the change in capacitive coupling for one of the intersections;

detecting each detected intersection from the image of change in capacitive coupling, wherein the value of the detected intersection is smaller than a first threshold and larger than a second threshold;

detecting each first region, wherein each first region includes one of the detected intersections and an intersection adjacent to the detected intersection, and the sum of values of the first region is greater than the first threshold; and

when at least one first region is detected, detecting a first region approached or touched by an external conductive object, wherein the values of all intersections adjacent to the first region approached or touched by the external conductive object are all smaller than a third threshold.

12. The method of claim 11, further comprising:

detecting each second region, wherein each second region includes four adjacent intersections including one of the detected intersection, and the sum of values of the second region is greater than the first threshold; and

when at least one second region is detected, detecting a second region approached or touched by an external conductive object, wherein the values of all intersections adjacent to the second region approached or touched by the external conductive object are all smaller than the third threshold.

13. The method of claim 11, wherein the first threshold>

the second threshold>

the third threshold.

14. The method of claim 11, wherein the second threshold is ½

of the first threshold, and the third threshold is ¼

of the first threshold.

15. The method of claim 11, wherein the maximum width of the approach or touch of a small area by an external conductive object is less than the distance between the centers of two conductive strips arranged adjacent and in parallel with each other, the two conductive strips arranged adjacent and in parallel with each other are the driven conductive strips or the sensed conductive strips.

16. The method of claim 11, wherein each first region or second region determined to be approached or touched by an external conductive object is a first region or a second region approached or touched by a pen, wherein the maximum width on the touch sensor touched by the pen is less than or equal to 3 mm.

17. A device for detecting an approach or a touch of a small area, comprising:

a means for obtaining an image of change in capacitive coupling from a capacitive touch sensor, wherein the capacitive touch sensor includes a plurality of driven conductive strips driven by a driving signal and a plurality of sensed conductive strips providing changes in capacitive coupling, each time the driving signal is provided, one or more intersections between one or more of the conductive strips being simultaneously driven by the driving signal and each sensed conductive strip generate capacitive coupling, and each value in the image of change in capacitive coupling is the change in capacitive coupling for one of the intersections;

a means for detecting each detected intersection from the image of change in capacitive coupling, wherein the value of the detected intersection is smaller than a first threshold and larger than a second threshold;

a means for detecting each first region, wherein each first region includes one of the detected intersections and an intersection adjacent to the detected intersection, and the sum of values of the first region is greater than the first threshold; and

a means for detecting a first region approached or touched by an external conductive object when at least one first region is detected, wherein the values of all intersections adjacent to the first region approached or touched by the external conductive object are all smaller than a third threshold.

18. The device of claim 17, further comprising:

a means for detecting each second region, wherein each second region includes four adjacent intersections including one of the detected intersection, and the sum of values of the second region is greater than the first threshold; and

a means for detecting a second region approached or touched by an external conductive object when at least one second region is detected, wherein the values of all intersections adjacent to the second region approached or touched by the external conductive object are all smaller than the third threshold.

19. The device of claim 17, wherein the first threshold>

the second threshold>

the third threshold.

20. The device of claim 17, wherein the second threshold is ½

of the first threshold, and the third threshold is ¼

of the first threshold.

21. The device of claim 17, wherein the maximum width of the approach or touch of a small area by an external conductive object is less than the distance between the centers of two conductive strips arranged adjacent and in parallel with each other, the two conductive strips arranged adjacent and in parallel with each other are the driven conductive strips or the sensed conductive strips.

22. The device of claim 17, wherein each first region or second region determined to be approached or touched by an external conductive object is a first region or a second region approached or touched by a pen, wherein the maximum width on the touch sensor touched by the pen is less than or equal to 3 mm.

23. A method for detecting an approach or a touch of a small area, comprising:

obtaining an image of change in capacitive coupling from a capacitive touch sensor, wherein the capacitive touch sensor includes a plurality of driven conductive strips driven by a driving signal and a plurality of sensed conductive strips providing changes in capacitive coupling, each time the driving signal is provided, one or more intersections between one or more of the conductive strips being simultaneously driven by the driving signal and each sensed conductive strip generate capacitive coupling, and each value in the image of change in capacitive coupling is the change in capacitive coupling for one of the intersections;

detecting each intersection with a value greater than a first threshold from the image of change in capacitive coupling; and

determining a single intersection of an approach or a touch of a small area by each external conductive object when at least one intersection with the value greater than the first threshold is detected, wherein all intersections adjacent to the single intersection of the approach or touch of a small area by each external conductive object are all smaller than the first threshold.

24. The method of claim 23, further comprising:

detecting each detected intersection from the image of change in capacitive coupling, wherein the value of each detected intersection is smaller than the first threshold and larger than a second threshold; and

detecting each first region, wherein each first region includes one of the detected intersections and an intersection adjacent to the detected intersection, and the sum of values of the first region is greater than the first threshold; and

detecting a first region approached or touched by an external conductive object when at least one first region is detected, wherein the values of all intersections adjacent to the first region approached or touched by the external conductive object are all smaller than a third threshold.

25. The method of claim 24, further comprising:

detecting each second region if no first region is detected, wherein each second region includes four adjacent intersections including one of the detected intersection, and the sum of values of the second region is greater than the first threshold; and

detecting a second region approached or touched by an external conductive object when at least one second region is detected, wherein the values of all intersections adjacent to the second region approached or touched by the external conductive object are all smaller than the third threshold.

26. The method of claim 24, wherein the first threshold>

the second threshold>

the third threshold.

27. The method of claim 24, wherein the second threshold is ½

of the first threshold, and the third threshold is ¼

of the first threshold.

28. The method of claim 23, wherein the maximum width of the approach or touch of a small area by an external conductive object is less than the distance between the centers of two conductive strips arranged adjacent and in parallel with each other, the two conductive strips arranged adjacent and in parallel with each other are the driven conductive strips or the sensed conductive strips.

29. The method of claim 25, wherein each first region or second region determined to be approached or touched by an external conductive object is a first region or a second region approached or touched by a pen, wherein the maximum width on the touch sensor touched by the pen is less than or equal to 3 mm.