Touch sensing device and method of identifying a touched position

• US 9,552,111 B2
• Filed: 02/05/2014
• Issued: 01/24/2017
• Est. Priority Date: 02/08/2013
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: Tanaka, Hiroshi
• Primary Examiner(s): Sasinowski, Andrew
• Assistant Examiner(s): OLIVER, GERALD L
• Application Number:
  US14/172,935
• Publication Number:
  US 20140225863A1
• Time in Patent Office: 1,084 Days
• Field of Search: 345173-178
• US Class Current: 1/1
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

In a touch sensing device of a capacitive type, touch coordinates are obtained according to a detected signal corresponding to a variation in a mutual capacitance between an X-electrode and a Y-electrode due to a finger touch in each combination of a plurality of X-electrodes and a plurality of Y-electrodes within a sensing area. The theoretical value of the detected signal in each combination of the X-electrodes an the Y-electrodes approximately expressed by a two-dimensional Gaussian function. The touch coordinates are identified correctly by finding the optimal solution of the object function which expresses the sum of squared differences between each of the theoretical signal value and the detected signal value.

Claims

1. A touch sensing device comprising:

a touch sensor panel;

a sensing area formed on the touch sensor panel for detecting a touch coordinate;

a plurality of first electrodes formed in the sensing area and extending along a first direction;

a plurality of second electrodes formed in the sensing area and extending along a second direction intersected the first direction;

a plurality of cross points of the plurality of first electrodes and the plurality of second electrodes;

a touch detection unit that detects a detected signal value corresponding to the plurality of cross points;

a coordinate calculation unit that calculates tentative touch coordinates based on the detected signal value, and that calculates theoretical values of the plurality of cross points based on the tentative touch coordinates; and

a plurality of connecting wirings formed on the touch sensor panel outside the sensing area,

wherein the plurality of connecting wirings are connected to the plurality of first electrodes and the plurality of second electrodes on an end of the sensing area, respectively,

wherein the coordinate calculation unit determines, based on the tentative touch coordinates, whether a first area within the sensing area is touched, or a second area within the sensing area is touched,

wherein the second area is closer to the end of the sensing area than the first area, and includes an outermost electrode of the plurality of electrodes, and

wherein, in case that the coordinate calculation unit determined the second area is touched, the coordinate calculation unit obtains touch coordinates by calculation using least squares linear Taylor differential correction method with the tentative touch coordinate of the second area, which is an initial value of the calculation.

2. The touch sensing device according to claim 1, wherein the tentative touch coordinates are a centroid of the detected signal value of the plurality of cross points.

3. The touch sensing device according to claim 2, wherein the theoretical values are calculated by a two-dimensional Gaussian function that has a maximum point at the touch coordinates.

4. The touch sensing device according to claim 1, wherein

the coordinate calculation unit obtains touch coordinates by a calculation method different from that for the second area if it is determined that the first area is touched.

5. The touch sensing device according to claim 1,

wherein the coordinate calculation unit further includes a communication unit that transmits a signal indicative of whether to obtain the touch coordinates.