PROPORTIONAL AREA WEIGHTED SENSOR FOR TWO-DIMENSIONAL LOCATIONS ON A TOUCH SCREEN

• US 20120127130A1
• Filed: 12/22/2010
• Published: 05/24/2012
• Est. Priority Date: 11/22/2010
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: JUNG, DAVID HANN
• Granted Patent: US 8,390,591 B2
• Time in Patent Office: Days
• US Class Current: 345/178
• 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 is provided including a controller and a planar layout having an edge and an interior portion. Further including a connector coupling the touch controller to the layout; a substrate made of a first material; and sensing elements made of a second material formed on the substrate and covering the layout without overlapping. Sensing elements have non-monotonic widths from the center along two perpendicular directions, and a centroid. The touch sensor including pass-through traces to couple edge to interior portions to determine two-dimensional locations for touches using a weighting that is proportional to an overlap area of the sensor elements and their centroids. The substrate may be made of a dielectric and the sensing elements made of a conductor. A method for using a controller circuit having a memory to store centroid locations and determine a two-dimensional location on a touch screen as above is also provided.

Claims

1. A touch sensor comprising:

a touch controller;

a touch surface comprising a planar touch sensor layout, the layout having an edge portion and an interior portion;

a connector coupling the touch controller to the layout;

a substrate made of a first material comprising the layout; and

sensing elements made of a second material formed on the substrate and covering the layout without overlapping, wherein;

the sensing elements each have a width that varies non-monotonically from a center of the sensing element along two substantially perpendicular directions on the layout, and a centroid;

at least one pass-through trace to couple the edge portion of the layout to a sensing element in the interior portion of the layout; and

the sensor determines a two-dimensional location for a touch overlapping the sensing elements using a weighting that is proportional to an overlap area of the sensor elements and their centroids.

2. The touch sensor of claim 1, wherein the touch controller comprises a processor circuit and a memory.

3. The touch sensor of claim 1 wherein the connector comprises a plurality of coupling channels, each of the coupling channels coupling a single sensing element to the touch controller.

4. The touch sensor of claim 1, wherein the sensing elements are separated from each other by a fixed gap.

5. The touch sensor of claim 1, wherein the sensing elements completely embedded in the interior portion have a shape that is substantially symmetric upon reflections about two axes in the plane of the layout, excepting the pass through traces.

6. The touch sensor of claim 1, wherein the sensing elements have a shape interlaced with other sensing elements so that a line joining a point inside one element to its centroid crosses over a neighboring element at least once.

7. The touch sensor of claim 1, wherein the touch sensor comprises a single layer capacitive sensor.

8. A touch sensor comprising:

a touch controller;

a touch surface comprising a planar touch sensor layout, the layout having

an edge portion and an interior portion;

a connector coupling the touch controller to the layout;

a substrate made of a dielectric material comprising the layout; and

sensing elements made of a conductive material formed on the substrate and covering the layout without overlapping, wherein;

the sensing elements each have a width that varies non-monotonically from a center of the sensing element along two substantially perpendicular directions on the layout, and a centroid;

at least a pass-through trace to couple the edge of the layout to a sensing element in the interior portion of the layout; and

the sensor determines a two-dimensional location for a touch overlapping the sensing elements using a weighting that is proportional to an overlap area of the sensor elements and their centroids.

9. The touch sensor of claim 8, wherein the touch controller comprises a processor circuit and a memory.

10. The touch sensor of claim 8, wherein the sensing elements are capacitively coupled by a touch from a capacitive element.

11. The touch sensor of claim 8, wherein the capacitive element is selected from the group consisting of at least a finger, a stylus and a pointing device made of a dielectric material.

12. The touch sensor of claim 8, wherein the conductive material comprises Indium Tin Oxide (ITO).

13. A a controller circuit comprising a processor and a memory, the memory including instructions that, when executed by the processor, cause the processor to perform a method for determining a two-dimensional location on a touch screen having an interior portion and an edge portion, the method comprising:

obtaining, by the controller, overlap proportions from a plurality of sensing elements in the touch screen, each sensing element of the plurality of sensing elements having a centroid, wherein

the centroid locations are stored in the memory;

determining, by the processor, a first two-dimensional touch location by an average of the centroid locations of the plurality of sensing elements weighted by the overlap proportion;

determining, by the processor, complementary factors using the first two-dimensional touch location; and

determining, by the processor, a second two-dimensional touch location by an average of the locations of each of a plurality of sensing elements weighted by the overlap proportion and the complementary factors.

14. The method of claim 13, wherein determining complementary factors using the first two-dimensional touch location comprises determining whether or not the first two-dimensional touch location is included in the interior portion or the edge portion of the touch screen.

15. The method of claim 13, determining complementary factors using the first two-dimensional touch location comprises determining the distance between the first two-dimensional touch location and the centroid of each sensing element.

16. The method of claim 15, wherein the complementary factor associated to a sensing element for a touch location is inversely proportional to the distance of the first two-dimensional touch location and the centroid of each sensing element.

17. The method of claim 13, wherein the sensing elements are electronically coupled to the controller circuit, the method further comprising:

adjusting the complementary factor associated to a sensing element for a touch location for aberrations caused by the sensing capability of each sensing element and their electronic coupling to the controller circuit.

18. The method of claim 13, wherein determining complementary factors using the first two-dimensional touch location comprises obtaining the complementary factors from the memory.

19. The method of claim 13, wherein determining complementary factors using the first two-dimensional touch location comprises using a function stored in a memory circuit in the controller circuit.

20. The method of claim 13, wherein determining complementary factors using the first two-dimensional touch location comprises using a lookup table stored in a memory circuit in the controller circuit.