Touch sensitive display device and method of determining touch

• US 8,199,129 B2
• Filed: 06/25/2009
• Issued: 06/12/2012
• Est. Priority Date: 12/16/2008
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Jung, Ho-Yong, Choi, Uk-Chul
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Lubit, Ryan A
• Application Number:
  US12/492,028
• Publication Number:
  US 20100149131A1
• Time in Patent Office: 1,083 Days
• Field of Search: 345156-183, 178 1801- 2004
• US Class Current: 345/175
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

In a method for determining a contact of a display device according to an exemplary embodiment, a covariance matrix is used to extract a unique vector and a unique value and to obtain the main component through the unique vector and the unique value. The value of the main component is analyzed to determine the contact existence. The unique vector and the unique value are used to extract the main component, and then the contact existence is determined such that the touch existence and the position thereof may be correctly determined without errors.

Claims

1. A method for determining a contact of a display device, comprising:

receiving a sensing data signal from each light sensor of a matrix of light sensors arranged in rows and columns; and

determining a touch existence and a position thereof by extracting and analyzing a component of the sensing data signal;

wherein the determining of the touch existence and the position thereof further includes;

selecting at least a portion of each sensing data signal as an analysis matter;

assembling a first matrix of sensed data signals, the matrix of sensed data signals having row elements corresponding to the selected portions of the sensing data signals from respective rows of the light sensors, and column elements corresponding to the selected portions of the sensing data signals from respective columns of the light sensors;

determining a second matrix of sensed data signals by, for each row of the first matrix of sensed data signals, determining an average value of the row elements of that row, and subtracting the average value from each row element of that row;

determining a covariance matrix from the second matrix;

determining eigenvalues of the covariance matrix;

selecting highest values of the eigenvalues, and selecting columns of the covariance matrix corresponding to the selected highest values of the eigenvalues;

determining the touch existence according to whether values of elements of the selected columns fall within one or more predetermined ranges.

2. The method of claim 1, wherein the analysis matter is selected with reference to a threshold voltage.

3. The method of claim 2, wherein the analysis matter is selected according to whether the corresponding sensing data signals of a predetermined number of consecutive row or column elements each fall below the threshold voltage.

4. The method of claim 3, wherein the analysis matter is the entire row including the analysis matter.

5. The method of claim 3, wherein more than one analysis matter is selected.

6. The method of claim 1, wherein the covariance matrix is determined by the equation below:

7. The method of claim 1, wherein the determining eigenvalues is executed by the equation below:

det|−

λ

|=0

wherein the det means a determinant, C is the covariance matrix and the λ

is a matrix of the eigenvalues.

8. The method of claim 1, wherein the selecting highest values further comprises selecting the two highest values of the eigenvalues.

9. The method of claim 8, wherein the touch existence is determined when the values of the elements of the selected columns corresponding to the two highest values of the eigenvalues each fall within the one or more predetermined ranges.

10. The method of claim 9, wherein the predetermined range is determined as a specific range or ones of the selected columns corresponding to portions of the display device not receiving the contact.

11. A display device comprising:

a display panel;

a plurality of pixels formed in the display panel;

a plurality of light sensors formed in the display panel; and

a controller programmed to determine the existence of a touch upon the display panel, by performing the following;

selecting at least a portion of each sensing data signal as an analysis matter;

assembling a first matrix of sensed data signals, the matrix of sensed data signals having row elements corresponding to the selected portions of the sensing data signals from respective rows of the light sensors, and column elements corresponding to the selected portions of the sensing data signals from respective columns of the light sensors;

determining a second matrix of sensed data signals by, for each row of the first matrix of sensed data signals, determining an average value of the row elements of that row, and subtracting the average value from each row element of that row;

determining a covariance matrix from the second matrix;

determining eigenvalues of the covariance matrix;

selecting highest values of the eigenvalues, and selecting columns of the covariance matrix corresponding to the selected highest values of the eigenvalues;

determining the touch existence according to whether values of elements of the selected columns fall within one or more predetermined ranges.

12. The display device of claim 11, wherein the display device is one of a liquid crystal display, an organic light emitting device, and an electrophoretic display.

13. The display device of claim 11, further comprising:

an image scan unit and an image data driver connected to the pixels; and

a sensing scan unit and a sensing signal processor connected to the plurality of light sensors.

14. The display device of claim 13, further comprising a signal controller controlling the image scan unit, the image data driver, the sensing scan unit, and the sensing signal processor.