Alternating, complementary conductive element pattern for multi-touch sensor
View Patent ↗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.
1. A method of determining touch locations on a touch sensor having conductive elements connected to a touch controller, the touch controller configured to measure changes in capacitance of each of the conductive elements, the method comprising:
(a) selecting a group of conductive elements overlapped by a touch based on the measurements of the touch controller;
(b) determining a weighted average of coordinates of centers of each of the conductive elements;
(c) associating a touch position with the determined weighted average of the selected group of overlapping conductive elements;
(d) selecting a first conductive element in the group of conductive elements overlapped by a touch that has a largest overlapping area;
(e) selecting a threshold area for sensitivity;
(f) determining if the largest overlapping area is greater than the preselected threshold;
(g) selecting a first group of elements surrounding the selected first conductive element;
(h) using coordinates of centers of each of the conductive elements in the first group of conducting elements to determine a weighted average of said coordinates;
(i) associating a touch position with the determined weighted average of the first group of conductive elements;
(j) 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
(k) repeating steps (d) through (j) with remaining conductive elements in the group of overlapping elements.
2. The method of claim 1 , wherein determining the weighted average comprises:
measuring a change in capacitance 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.
3. The method of claim 1 , further comprising:
finding the touch positions of multiple, simultaneous touches on the touch sensor.
4. A method of determining touch locations on a touch sensor having conductive elements connected to a touch controller, the touch controller configured to measure changes in capacitance of each of the conductive elements, the method comprising:
(a) selecting a group of conductive elements overlapped by a touch based on the measurements of the touch controller;
(b) determining a weighted average using coordinates of centers of each of the conductive elements;
(c) associating a touch position with the determined weighted average of the selected group of overlapping conductive elements;
(d) selecting a first conductive element in the group of conductive elements overlapped by a touch;
(e) selecting a first group of immediate neighboring elements of the first conductive element;
(f) 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;
(g) selecting a second group of immediate neighboring elements of the first major touch element;
(h) selecting a third group comprising the conductive elements that are common to the first group and the second group;
(i) determining a weighted average of coordinates of centers of each of the conductive elements in the third group of conducting elements;
(j) assigning a touch position with the determined weighted average of the selected third group of conductive elements;
(k) 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; and
repeating steps (d) through (k) with the remaining conductive elements in the group of overlapping elements until no elements can be selected as first conductive elements.
5. The method of claim 4 , wherein determining the weighted average comprises:
measuring a change in capacitance 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.
6. The method of claim 4 , further comprising:
finding the touch positions of multiple, simultaneous touches on the touch sensor.