ALTERNATING, COMPLEMENTARY CONDUCTIVE ELEMENT PATTERN FOR MULTI-TOUCH SENSOR

• US 20100079393A1
• Filed: 08/18/2009
• Published: 04/01/2010
• Est. Priority Date: 10/01/2008
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: DEWS, Christopher William
• Granted Patent: US 8,941,595 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• 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
• 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 touch sensor includes conductive elements of substantially concave shape to enable detection of multiple simultaneous touches in at least two directions, with reduced noise sensitivity and enhanced accuracy. The shapes of the conductive elements may be similar, or may be alternating, complementary shapes that cover substantially all of the sensor area. The conductive elements physically interact with adjacent elements in such a way that the area covered by a touch changes monotonically from overlapping substantially all of one element to overlapping substantially all of an adjacent element as the touch area is moved from one element to the other element along a line between the centers of those adjacent elements. Such monotonic change of touch overlap area may occur simultaneously in two orthogonal directions. Connections from internally positioned conductive elements to a touch controller may be made to pass through other conductive elements.

Claims

1. A touch sensor for determining touch locations in an area, comprising:

conductive elements of pre-selected substantially concave shapes, arranged to substantially fill an area of the sensor;

a touch controller comprising a processor circuit and a memory circuit;

connectors comprising conductive elements coupling the touch controller to each of the conductive elements.

2. The touch sensor of claim 1, wherein the conductive elements have alternating, complementary shapes.

3. The touch sensor of claim 2, wherein the alternating conductive elements can have any one of at least two complementary shapes;

the at least two complementary shapes having approximately the same area; and

further wherein

each of the conductive elements having a first shape is located next to a conductive element having a complementary second shape.

4. The touch sensor of claim 3 wherein a difference in the areas between the at least two complementary shapes is compensated by the touch controller.

5. The touch sensor of claim 1 wherein the conductive elements have identical shape.

6. The touch sensor of claim 5 wherein the shape of the conductive elements is a cross formed by two interlocking quadrilateral figures, essentially orthogonal to each other.

7. The touch sensor of claim 1 wherein the conductive elements are formed in a single-layer.

8. The touch sensor of claim 1, wherein the conductive elements are arranged so that the proportion of the area covered by a touch which overlaps a first conductive element is reduced monotonically from about 100% to about 0%, while the proportion of the area which overlaps a second, adjacent conductive element is monotonically increased from about 0% to about 100%, as the touch area is moved from the center of the first conductive element to the center of the second, adjacent conductive element.

9. The touch sensor of claim 8, wherein such monotonic change of touch overlap area between a first conductive element and a second, adjacent conductive element, takes place when the first conductive element and the second conductive element are displaced relative to each other in either of two different directions;

and the two different directions are essentially orthogonal to each other.

10. The touch-sensor of claim 9 wherein the connectors are made to pass through other conductive elements in order to reach a selected conductive element.

11. The touch-sensor of claim 3 wherein the first shape is a star shape and the complementary, second shape is a cross shape;

and

the star shape and the cross shape snug and fit closely with each other, with little uncovered space in between the conductive elements.

12. A method of determining touch locations on a touch sensor, comprising:

having conductive elements of preselected, substantially concave shapes;

having a touch controller comprising a processor circuit and a memory circuit;

having connectors comprising conductive elements connecting the touch controller to the conductive elements;

using the touch controller to measure changes in the capacitance of each of the conductive elements, as a result of the contact with the sensor by a user;

selecting a group of conductive elements overlapped by a touch based on the measurements of the touch controller;

using the coordinates of the centers of each of the conductive elements to evaluate a weighted average of said coordinates; and

associating a touch position with the evaluated weighted average of the selected group of overlapping conductive elements.

13. The method of claim 12 further wherein:

the weighted average is determined according to the change in capacitance measured for each of the conductive elements in the selected group of conductive elements overlapped by a touch, relative to the total surface area of all the conductive elements in the selected group of conductive elements overlapped by a touch.

14. The method of claim 13 wherein the touch position corresponds to a single touch applied to the touch-sensor sensor.

15. The method of claim 12 further comprising:

selecting a first conductive element in the group of conductive elements overlapped by a touch that has the largest overlapping area;

selecting a threshold area for sensitivity;

determining if the largest overlapping area is greater than the preselected threshold;

selecting a first group of the surrounding elements of the selected first conductive element;

using the coordinates of the centers of each of the conductive elements in the first group of conducting elements to evaluate a weighted average of said coordinates; and

associating a touch position with the evaluated weighted average of the first group of conductive elements;

marking the first conductive element in said selected first group as ‘

used’ and

removing the first conductive element from further consideration in the measurements; and

repeating the steps outlined above with the remaining conductive elements in the group of overlapping elements.

16. The method of claim 15, further comprising

the weighted average is determined according to the change in capacitance measured for each of the conductive elements in the first group of conductive elements, relative to the total surface area of all the conductive elements in the selected first group of conductive elements.

17. The method of claim 15, further comprising:

finding the touch positions of multiple, simultaneous touches on the touch-sensitive sensor.

18. The method of claim 12 further comprising:

selecting a first conductive element in the group of conductive elements overlapped by a touch;

selecting a first group of immediate neighboring elements of the first conductive element;

selecting a first major touch element from the selected first group of conducting elements overlapped by a touch, which has the largest overlap area in the selected first group;

selecting a second group of immediate neighboring elements of the first major touch element;

selecting a third group comprising the conductive elements that are common to the first group and the second group;

using the coordinates of the centers of each of the conductive elements in the third group of conducting elements to evaluate a weighted average of said coordinates; and

assigning a touch position with the evaluated weighted average of the selected third group of conductive elements;

marking the conductive elements in the third group as ‘

partially used’

so that they are not used as a first conductive element in further steps;

repeating the steps outlined above with the remaining conductive elements in the group of overlapping elements until no elements can be selected as first conductive elements.

19. The method of claim 18, further comprising:

performing the weighted average according to the change in capacitance measured for each of the conductive elements in the third group of conductive elements, relative to the total surface area of all the conductive elements in the third group of conductive elements.

20. The method of claim 18, further comprising:

finding the touch positions of multiple, simultaneous touches on the touch-sensitive sensor.