Capacitive touch sensor and capacitive pen

• US 10,007,361 B2
• Filed: 12/17/2012
• Issued: 06/26/2018
• 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
• Primary Examiner(s): Adediran, Abdul-Samad A
• Application Number:
  US13/716,880
• Publication Number:
  US 20130155016A1
• Time in Patent Office: 2,017 Days
• Field of Search: 178 1803, 345173-174, 345179, 345175, 715863
• 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, wherein the image of change in capacitive coupling is generated by an external conductive object, and a maximum width of the approach or touch of a small area by the external conductive object is less than a distance between centers of two conductive strips arranged adjacent and in parallel with each other;

detecting each detected intersection from the image of change in capacitive coupling, wherein a value of the detected intersection is smaller than a first threshold and larger than a second threshold and said value of the detected intersection is added to an adjacent intersection value for comparing with the first threshold, wherein the second threshold is ½

of the first threshold, and the first and second thresholds are set before obtaining the image;

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

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 a sum of values of the second region is greater than the first threshold.

2. The method of claim 1, wherein further comprising determining the first region or the second region approached or touched by the 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.

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

the second threshold>

the third threshold.

4. The method of claim 2, wherein the third threshold is ¼

of the first threshold.

5. The method of claim 1, wherein the two conductive strips arranged adjacent and in parallel with each other are the driven conductive strips or the sensed conductive strips.

6. 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.

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

a memory, wherein a plurality of programs are stored in the memory; and

a processor accessing the programs and executing the following operations;

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, wherein the image of change in capacitive coupling is generated by an external conductive object, and a maximum width of the approach or touch of a small area by the external conductive object is less than a distance between centers of two conductive strips arranged adjacent and in parallel with each other;

detecting each detected intersection from the image of change in capacitive coupling, wherein a value of the detected intersection is smaller than a first threshold and larger than a second threshold and said value of the detected intersection is added to an adjacent intersection value for comparing with the first threshold, wherein the second threshold is ½

of the first threshold, and the first and second thresholds are set before obtaining the image;

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

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 a sum of values of the second region is greater than the first threshold.

8. The device of claim 7, wherein the processor further executes the following operations:

determining the first region or the second region approached or touched by the 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.

9. The device of claim 8, wherein the first threshold>

the second threshold>

the third threshold.

10. The device of claim 8, wherein the third threshold is ¼

of the first threshold.

11. The device of claim 7, wherein the two conductive strips arranged adjacent and in parallel with each other are the driven conductive strips or the sensed conductive strips.

12. The device of claim 7, 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.

13. 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, wherein the image of change in capacitive coupling is generated by an external conductive object, and a maximum width of the approach or touch of a small area by the external conductive object is less than a distance between centers of two conductive strips arranged adjacent and in parallel with each other;

detecting each detected intersection from the image of change in capacitive coupling, wherein a value of the detected intersection is smaller than a first threshold and larger than a second threshold and said value of the detected intersection is added to an adjacent intersection value for comparing with the first threshold, wherein the second threshold is ½

of the first threshold, and the first and second thresholds are set before obtaining the image; and

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

14. The method of claim 13, further comprising:

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

15. The method of claim 14, further comprising:

detecting each second region, wherein each second region includes four adjacent intersections including one of the detected intersection, and a 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 a plurality of values of all intersections adjacent to the second region approached or touched by the external conductive object are all smaller than the third threshold.

16. The method of claim 14, wherein the first threshold>

the second threshold>

the third threshold.

17. The method of claim 14, wherein the third threshold is ¼

of the first threshold.

18. The method of claim 13, wherein the two conductive strips arranged adjacent and in parallel with each other are the driven conductive strips or the sensed conductive strips.

19. The method of claim 13, 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 a maximum width on the touch sensor touched by the pen is less than or equal to 3 mm.

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

a memory, wherein a plurality of programs are stored in the memory; and

a processor accessing the programs and executing the following operations;

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, wherein the image of change in capacitive coupling is generated by an external conductive object, and a maximum width of the approach or touch of a small area by the external conductive object is less than a distance between centers of two conductive strips arranged adjacent and in parallel with each other;

detecting each detected intersection from the image of change in capacitive coupling, wherein a value of the detected intersection is smaller than a first threshold and larger than a second threshold and said value of the detected intersection is added to an adjacent intersection value for comparing with the first threshold, wherein the second threshold is ½

of the first threshold, and the first and second thresholds are set before obtaining the image; and

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

21. The device of claim 20, wherein the processor further executes the following operations:

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

22. The device of claim 21, further executing the following operations:

detecting each second region, wherein each second region includes four adjacent intersections including one of the detected intersection, and a 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 a plurality of values of all intersections adjacent to the second region approached or touched by the external conductive object are all smaller than the third threshold.

23. The device of claim 21, wherein the first threshold>

the second threshold>

the third threshold.

24. The device of claim 21, wherein the third threshold is ¼

of the first threshold.

25. The device of claim 20, wherein the two conductive strips arranged adjacent and in parallel with each other are the driven conductive strips or the sensed conductive strips.

26. The device of claim 20, 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 a maximum width on the touch sensor touched by the pen is less than or equal to 3 mm.