TWO-DIMENSIONAL TOUCH PANEL

• US 20100193258A1
• Filed: 07/07/2008
• Published: 08/05/2010
• Est. Priority Date: 07/12/2007
• Status: Active Grant

• Current Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Simmons, Martin John, Yilmaz, Esat
• Granted Patent: US 8,842,091 B2
• Time in Patent Office: Days
• US Class Current: 178/18.06
• 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality

Abstract

A capacitive touch panel is provided capable of detecting multiple simultaneous touches. The touch panel delivers sets of capacitance signal values to a processor which computes the coordinates of single or multiple touch locations on the touch panel. The processing of each set is performed by (i) identifying the sensing element having the largest capacitance signal value; (ii) defining a region around that sensing element; and (iii) repeating the process iteratively, wherein each subsequent identifying step excludes signals that lie in previously defined regions. A multi-touch sensor is thus provided in which the signal processing is based on successive definition of regions or sub-blocks in the touch: panel. The touch location in each region can be determined more accurately by then applying interpolation between the adjacent signal values. This allows for position resolution at a finer scale than that defined by the touch panel'"'"'s electrode patterning.

Claims

1. A 2D touch-sensitive capacitive position sensor comprising:

(a) a touch panel having a plurality of sensing elements distributed over its area;

(b) a capacitance measurement circuit connected to the sensing elements and operable repeatedly to acquire sets of capacitance signal values, each set being made up of a capacitance signal value from each of the sensing elements; and

(c) a processor connected to receive the sets of capacitance signal values and operable to process each set to compute and output coordinates of single or multiple touch locations on the touch panel, the processing of each set being performed by;

(i) identifying the sensing element having the largest capacitance signal value;

(ii) defining a region of the touch panel including said sensing element having the largest capacitance signal value and selected ones of its neighbours;

(iii) identifying and defining one or more further sensing elements and regions respectively, wherein each iteration excludes capacitance signal values from consideration if they lie in previously defined regions of the touch panel; and

(iv) outputting data indicating the coordinates of the touch location in each region identified.

2. The sensor of claim 1, wherein the identifying steps exclude from consideration any sensing elements with capacitance signal values that are not above a threshold value.

3. The sensor of claim 1, wherein the sensing element in each region that has the largest capacitance value is taken to be the principally actuated sensing element of that region.

4. The sensor of claim 1, wherein the sensing element in each region that is at the highest position on the touch panel among those sensing elements that have a capacitance signal value above a threshold value is taken to be the principally actuated sensing element of that region.

5. The sensor of claim 4, wherein the touch location in each region is taken to be at the principally actuated sensing element.

6. The sensor of any preceding claim, wherein the touch location in each region is determined by applying interpolation between the capacitance signal values of at least some of the sensing elements in that region.

7. The sensor of claim 6, when appended to claim 3 or 4, wherein the interpolation is limited to the sensing element identified as being the principally actuated sensing element of the region and its neighbours.

8. The sensor of claim 6, wherein the interpolation includes all of the sensing elements in each region.

9. A method of processing signals from a 2D touch-sensitive capacitive position sensor comprising:

(a) a touch panel having a plurality of sensing elements distributed over its area;

(b) a capacitance measurement circuit connected to the sensing elements and operable repeatedly to acquire sets of capacitance signal values, each set being made up of a capacitance signal value from each of the sensing elements; and

(c) a 20 processor connected to receive the sets of capacitance signal values and operable to

process each set to compute and output coordinates of single or multiple touch locations on the touch panel, the method of processing each set comprising;

(i) identifying the sensing element having the largest capacitance signal value;

(ii) defining a region of the touch panel including said sensing element having the largest capacitance signal value and selected ones of its neighbours;

(iii) identifying and defining one or more further sensing elements and regions respectively, wherein each iteration excludes capacitance signal values from consideration if they lie in previously defined regions of the touch panel; and

(iv) outputting data indicating the coordinates of the touch location in each region identified.

10. The method of claim 9;

wherein the identifying steps exclude from consideration any sensing elements with capacitance signal values that are not above a threshold value.

11. The method of claim 9, wherein the sensing element in each region that has the largest capacitance value is taken to be the principally actuated sensing element of that region.

12. The method of claim 9, wherein the sensing element in each region that is at the highest position on the touch panel among those sensing elements that have a capacitance signal value above a threshold value is taken to be the principally actuated sensing element of that region.

13. The method of claim 11, wherein the touch location in each region is taken to be at the principally actuated sensing element.

14. The method claim 11, wherein the touch location in each region is determined by applying interpolation between the capacitance signal values of at least some of the sensing elements in that region.

15. The method of claim 14, wherein the interpolation is limited to the sensing element identified as being the principally actuated sensing element of the region and its neighbours.

16. The method of claim 14, wherein the interpolation includes all of the sensing elements in each region.