Display device and touch sensing method thereof

• US 9,075,259 B2
• Filed: 04/30/2013
• Issued: 07/07/2015
• Est. Priority Date: 12/07/2012
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kim, Sung Chul
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): JAVED, MAHEEN I
• Application Number:
  US13/873,420
• Publication Number:
  US 20140160062A1
• Time in Patent Office: 798 Days
• US Class Current: 1/1
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 2201/121 common or background
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G09G 3/36 using liquid crystals

Abstract

Disclosed is a display device. The display device includes a timing controller and a touch sensing unit. The timing controller temporally divides one frame period and drives a display panel such that a display mode for displaying an image in the display panel and a touch mode for sensing a user'"'"'s touch are alternately driven. The touch sensing unit detects the user'"'"'s touch with a DTX compensation value calculated by multiplying a DTX weight value and a maximum DTX amplitude of a touch sensing block which is obtained when a maximum grayscale value is applied to a plurality of pixels corresponding to the touch sensing block, in the touch mode. The DTX weight value is calculated by substituting an average value of grayscale values applied to the plurality of pixels corresponding to the touch sensing block into a normalization curve.

Claims

1. A display device, comprising:

a timing controller configured to;

temporally divide one frame period; and

drive a display panel such that a display mode for displaying an image in the display panel and a touch mode for sensing a user'"'"'s touch are alternately driven; and

a touch sensing unit configured to detect the user'"'"'s touch with a display to touch crosstalk (DTX) compensation value calculated by multiplying a DTX weight value and a maximum DTX amplitude of a touch sensing block, the maximum DTX amplitude being obtained when a maximum grayscale value is applied to a plurality of pixels corresponding to the touch sensing block, in the touch mode, the DTX weight value being calculated by substituting an average value of grayscale values applied to the plurality of pixels corresponding to the touch sensing block into a normalization curve,

wherein the normalization curve is calculated by normalizing DTX amplitude change characteristics of the touch sensing block based on changes in the grayscale values applied to the plurality of pixels corresponding to the touch sensing block.

2. The display device of claim 1, wherein the touch sensing unit comprises a normalizer configured to calculate the normalization curve in which:

an X-axis indicates the average value of grayscale values applied to the plurality of pixels corresponding to the touch sensing block; and

a Y-axis indicates a DTX amplitude of the touch sensing block based on the changes in the grayscale values.

3. The display device of claim 2, wherein the normalization curve is normalized for a Y-axis value to have 0 to 1 by dividing the DTX amplitude of the touch sensing block, based on the changes in the grayscale values, by a DTX amplitude of the touch sensing block which is obtained when a grayscale value is 255.

4. The display device of claim 1, wherein the touch sensing unit comprises a weight applier configured to calculate a value, corresponding to a Y-axis of the normalization curve, as a DTX weight value of the touch sensing block when the average value of grayscale values applied to the plurality of pixels corresponding to the touch sensing block is substituted into an X-axis of the normalization curve, in the display mode.

5. The display device of claim 1, wherein the touch sensing unit comprises a lookup table storage unit configured to measure the maximum DTX amplitude of the touch sensing block, which is obtained when the maximum grayscale value is applied to the plurality of pixels corresponding to the touch sensing block, to calculate a lookup table.

6. The display device of claim 1, wherein the touch sensing unit comprises a compensation value calculator configured to multiply the maximum DTX amplitude of the touch sensing block by the DTX weight value of the touch sensing block to calculate a DTX compensation value of the touch sensing block.

7. The display device of claim 1, wherein the touch sensing unit comprises a touch calculator configured to:

add the DTX compensation value to a user'"'"'s touch raw data measured from the touch sensing block to compensate for the touch raw data; and

compare the touch raw data and a touch threshold value to determine whether there is the user'"'"'s touch.

8. A touch sensing method of a display device, which temporally divides one frame period and drives a display panel such that a display mode for displaying an image in the display panel and a touch mode for sensing a user'"'"'s touch are alternately driven, the touch sensing method comprising:

substituting an average value of grayscale values applied to a plurality of pixels corresponding to a touch sensing block into a calculated normalization curve, in which an X-axis indicates the average value of grayscale values applied to the plurality of pixels corresponding to the touch sensing block and a Y-axis indicates a display to touch crosstalk (DTX) amplitude of the touch sensing block based on changes in the grayscale values, to calculate a DTX weight value in the touch mode; and

multiplying the DTX weight value and a maximum DTX amplitude of the touch sensing block, the maximum DTX amplitude being obtained when a maximum grayscale value is applied to the pixels corresponding to the touch sensing block, to calculate a DTX compensation value.

9. The touch sensing method of claim 8, further comprising, after the calculating of a DTX compensation value:

adding the DTX compensation value to a user'"'"'s touch raw data measured from the touch sensing block to compensate for the touch raw data; and

comparing the touch raw data and a touch threshold value to determine whether there is the user'"'"'s touch.

10. The touch sensing method of claim 8, further comprising, before the calculating of a DTX compensation value, measuring the maximum DTX amplitude of the touch sensing block, which is obtained when the maximum grayscale value is applied to the plurality of pixels corresponding to the touch sensing block, to calculate a lookup table.