SYSTEMS AND METHODS FOR DETECTING MULTIPLE TOUCH POINTS IN SURFACE-CAPACITANCE TYPE TOUCH PANELS

• US 20120262419A1
• Filed: 06/26/2012
• Published: 10/18/2012
• Est. Priority Date: 03/08/2010
• Status: Active Grant

• Current Assignee: Nuvoton Technology Corporation (Winbond Electronics Corporation)
• Original Assignee: Nuvoton Technology Corporation (Winbond Electronics Corporation)
• Inventors: HERSHMAN, Ziv, STOLOV, Ilia, NOSOVITSKY, Einat
• Granted Patent: US 9,146,644 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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

Abstract

A multi touch sensing module comprising a plurality of electrically conductive touch surfaces, each connected to at least one trace, wherein the touch surfaces are arranged in more than two columns, each including more than two touch surfaces, wherein touch surfaces in corresponding positions in said columns form staggered rows, and all touch surfaces reside in a single layer of electrically conductive material.

Claims

1. A multi touch sensing module comprising:

a plurality of electrically conductive touch surfaces, each connected to at least one trace, wherein the touch surfaces are arranged in more than two columns, each including more than 2 touch surfaces, wherein touch surfaces in corresponding positions in said columns form staggered rows, and all touch surfaces reside in a single layer of electrically conductive material.

2. The module of claim 1 wherein most of the touch surfaces are substantially longer along one dimension than along another dimension.

3. The module of claim 1 wherein most traces pass between, rather than through, touch surfaces.

4. The module of claim 2 wherein the touch surfaces have axes and the touch surfaces are staggered such that the axes of at least most of the touch surfaces define a ratio between them which is equal, order of magnitude, to a staggering level defined by said staggered touch surfaces.

5. The module of claim 2 wherein the electrically conductive touch surfaces satisfy:

0.6*{stagger level}<

={row pitch}/{column pitch}<

=1.8*{stagger level}).

6. The module of claim 1 wherein said rows have a staggering level equal to 2.

7. The module of claim 1 wherein the touch surfaces are rectangular.

8. The module of claim 1 and also comprising:

a contact sensing device including touch sensors operative to sense contact between a touching object and at least one of the plurality of electrically conductive touch surfaces; and

a processing unit, connected to the contact sensing device, which is operative for;

reading self-capacitance measurements generated by the contact sensing device, and resolving the touch sensor measurements into multiple locations of respective multiple objects which have come into contact with the touch surfaces.

9. The module of claim 8 wherein the processing unit times contact sensing measurements carried out by the contact sensing device to occur in groups such that capacitively coupled touch panel elements are not measured simultaneously.

10. The module of claim 8 in which the processing unit adjusts at least one individual touch sensor reading to compensate for known capacitive coupling effects of adjacent touch panel elements on the individual touch sensor reading.

11. The module of claim 8 wherein said resolving comprises compensating for possible distortion caused by staggering between linear arrays of touch surfaces, by converting readings of sensors connected to touch surfaces into a matrix of computed theoretical capacitance readings of virtual surfaces partitioned from the touch surfaces to form non-staggered rows of surfaces.

12. The module of claim 8 wherein said resolving comprises identifying sensed peaks on the touch panel.

13. The module of claim 12 wherein said identifying comprises finding peaks which represent possible touches and applying a peak removal test to filter out peaks that do not represent real touches.

14. The module of claim 12 wherein a peak splitting procedure is applied.

15. The module of claim 12 wherein computing coordinates of each individual peak comprises, for each coordinate along an x or y axis:

computing a weighted average of sensor readings generated by the touch sensors adjacent said individual peak where the weight of each sensor reading comprises a coordinate of a center of the sensor along said axis.

16. The module of claim 8 wherein said resolving comprises identifying sensed peaks on the touch panel, and in which the processing unit computes X and Y coordinates of peaks using sets of virtual surfaces partitioned from the touch surfaces to form non-staggered rows of surfaces, and wherein more rows of virtual surfaces than columns of virtual surfaces are used for X coordinate computation, and more columns of virtual surfaces than rows of virtual surfaces are used for Y coordinate computation.

17. The module of claim 16 wherein within rows and columns used for coordinate computation, at least one almost-adjacent virtual surface around a peak is used only if the almost-adjacent surface'"'"'s value is lower than or equal to a more directly-adjacent virtual surface around the peak.

18. The module of claim 1 wherein the traces extend beyond the active area of the touch panel only on one side of the touch panel and not on any side of the touch panel other than said one side.

19. The module of claim 1 wherein the portion of the traces connecting each of at least most of the touch surfaces with a corresponding active area terminal, are routed in non-straight lines such as a sequence of straight segments.

20. The module of claim 1 wherein the portion of the traces connecting each of at least most of the touch surfaces with a corresponding active area terminal, are routed in straight lines.

27. The module of claim 13 wherein at least one first peak which is adjacent to a second peak with a higher grade than the first peak, is filtered out.

28. The module of claim 8 wherein said resolving comprises using image processing.

29. The module of claim 8 wherein said resolving comprises using polynomial approximation.

21. A method for multi touch sensing comprising:

providing a plurality of electrically conductive touch surfaces, each connected to at least one trace, wherein the touch surfaces are arranged in more than two columns, each including more than 2 touch surfaces, wherein touch surfaces in corresponding positions in said columns form staggered rows, and all touch surfaces reside in a single layer of electrically conductive material; and

employing a processing unit which utilizes self-capacitance measurement for resolving multiple locations of multiple objects which have come into contact with the touch panel.

22. The method of claim 21 wherein most of the touch surfaces are substantially longer along one dimension than along another dimension.

23. The method of claim 21 wherein all traces pass between, rather than through, touch surfaces.

26. A method according to claim 21 wherein at least most of the touch surfaces have a first axis and a second, Y axis longer than the first axis, and wherein a peak is deemed to be indicative of two close touch objects along a single column arranged along the second axis, rather than being indicative of a single touch object, if a touch detection topology, characterized by a long flat plateau with sharp slopes along the second axis and a much shorter plateau, ruling out a thumb or wide single object, along the first axis, is detected.

24. A computer program product, comprising a non-transitory tangible computer readable medium having computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a touch detection method operative in conjunction with a plurality of electrically conductive touch surfaces, each connected to at least one trace, wherein the touch surfaces are arranged in more than two columns, each including more than 2 touch surfaces, wherein touch surfaces in corresponding positions in said columns form staggered rows, and all touch surfaces reside in a single layer of electrically conductive material, said method comprising:

reading self-capacitance measurements and resolving the touch sensor measurements into multiple locations of respective multiple objects which have come into contact with the touch surfaces,

wherein said resolving comprises

partitioning virtual surfaces from the touch surfaces to form non-staggered rows of surfaces; and

compensating for possible distortion caused by staggering between linear arrays of touch surfaces, by converting readings of sensors connected to touch surfaces into a matrix of computed theoretical capacitance readings of the virtual surfaces.

25. Apparatus according to claim 24 residing in a processing unit.