Liquid crystal display device

• US 10,139,960 B2
• Filed: 06/03/2016
• Issued: 11/27/2018
• Est. Priority Date: 09/24/2012
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: Tokita, Masahiro, Tsuyuzaki, Seiichi
• Primary Examiner(s): Ketema, Benyam
• Application Number:
  US15/172,293
• Publication Number:
  US 20160357346A1
• Time in Patent Office: 907 Days
• Field of Search: 345173
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• 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 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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

An in-cell type liquid crystal display device includes a first unit that detects whether a touch is present, or not, on the basis of a current flowing in a plurality of detection electrodes when a touch panel scanning voltage is applied to counter electrodes of each of M (M≥2) divided blocks, and a second unit that detects noise on the basis of a current flowing in the plurality of detection electrodes, assuming that an (M+1)^th counter electrode is present for the counter electrodes of each of the M divided blocks, and assuming that a touch panel scanning voltage synchronous with the touch panel scanning voltage applied to the counter electrodes of each of the M divided blocks is applied to the (M+1)^th counter electrode.

Claims

1. A display device comprising:

a display panel including a plurality of pixels, a plurality of detection electrodes, and common electrodes divided into M blocks when M is an integral number of 2 or more (M≥

2);

a driver circuit applying a common voltage and a touch panel scanning voltage to the common electrodes of each of the M divided blocks; and

a detector circuit detecting a touch signal of the plurality of detection electrodes,

wherein the common electrodes of each of the M divided blocks are shared with the respective pixels, and are also used as scanning electrodes,

wherein the driver circuit sequentially applies the touch panel scanning voltage to the common electrodes of each of the M divided blocks,

wherein the detector circuit determines;

in a normal touch detection process, a touch event by detecting the touch signal of the plurality of detection electrodes when the touch panel scanning voltage is applied to the common electrodes of each of the M divided blocks,

in a ghost touch detection process, a ghost touch event by detecting the touch signal of the plurality of detection electrodes without applying the touch panel scanning voltage to the M divided blocks,

wherein a threshold value for determining the touch event of the normal touch detection process is different from that for determining the ghost touch event of the ghost touch detection process,

wherein the detector circuit includes;

a plurality of integrating circuits provided each of the plurality of detection electrodes, and

an AD converter that converts an output voltage of the plurality of integrating circuits into digital data,

wherein each of the integrating circuits integrates a current of the respective detection electrodes, and

wherein the detector circuit determines the touch event with a first operating point of the AD converter, and the ghost touch event with a second operating point of the AD converter.

2. The display device according to claim 1,

wherein the first operating point is a value closer to the least significant bit than an intermediate value between the least significant bit and the most significant bit in the digital data converted by the AD converter, and the second operating point is the most significant bit in the digital data converted by the AD converter.

3. The display device according to claim 2,

wherein the touch event is determined when the digital data obtained by converting an integral value of the plurality of integrating circuits for each of the detection electrodes by the AD converter is a value between a first operating point and the most significant bit, and when a difference between the value of the digital data and the first operating point is larger than a first threshold value.

4. The display device according to claim 2,

wherein the ghost touch event is determined when the digital data obtained by converting an integral value of the plurality of integrating circuits for the detection electrode by the AD converter is a value between a second operating point and the least significant bit, and when a difference between the value of the digital data and the second operating point is larger than a second threshold value.

5. The display device according to claim 2,

wherein the digital data to be converted by the AD converter is data of 10 bits,

wherein the first operating point is a value of 250 to 350 decimally, and

wherein the second operating point is a value close to 1023 decimally.

6. The display device according to claim 1, further comprising:

an averaging filter which averages the digital data obtained by converting the integral value of the integrating circuits corresponding to the detection electrode when the ghost touch event is determined in the ghost touch detection process.

7. A display device comprising:

a display panel having a plurality of pixels arranged in a matrix, a plurality of detection electrodes, and common electrodes arranged along the respective pixels and divided into M blocks when M is an integral number of 2 or more (M≥

2);

a driver circuit applying a common voltage and a touch panel scanning voltage to the common electrodes of each of the M divided blocks; and

a detector circuit detecting a touch signal of the plurality of detection electrodes,

wherein the common electrodes of each of the M divided blocks are shared with the respective pixels of a plurality of continuous display lines, and are also used as scanning electrodes,

wherein the driver circuit sequentially applies the touch panel scanning voltage to the common electrodes of each of the M divided blocks, and

wherein the detector circuit is configured to;

determine a touch detected by the touch signal of the plurality of detection electrodes when the touch panel scanning voltage is applied to the common electrodes of each of the M divided blocks;

determine a noise detected by the touch signal of the plurality of detection electrodes, assuming that an (M+1)^th common electrode is present for the common electrodes of each of the M divided blocks, and assuming that a touch panel scanning voltage synchronous with the touch panel scanning voltage applied to the common electrodes of each of the M divided blocks is applied to the (M+1)^th common electrode; and

determine a ghost touch when the noise is determined by the detector circuit,

wherein a first touch position detecting process is executed when the noise is not determined by the detector circuit,

wherein when the noise is determined by the detector circuit, if the ghost touch is determined by the detector circuit, a second touch position detecting process is executed, and

wherein when the noise is detected by the detector circuit, if the ghost touch is not determined by the detector circuit, the second touch position detecting process is not executed.

8. The display device according to claim 7,

wherein the detector circuit includes:

a plurality of integrating circuits provided every plural detection electrodes; and

an AD converter that converts an output voltage of the plurality of integrating circuits into digital data.

9. The display device according to claim 8,

wherein each of the integrating circuits integrates a current of the respective detection electrodes when the touch panel scanning voltage is applied to the common electrodes of each of the M divided blocks, and when a fictional touch panel scanning voltage is applied to the fictional (M+1)^th common electrode.

10. The display device according to claim 8,

wherein the detector circuit is configured to determine the touch with a first operating point that is a value closer to the least significant bit than an intermediate value between the least significant bit and the most significant bit in the digital data converted by the AD converter, and

the detector circuit is configured to determine the ghost touch with a second operating point that is the most significant bit in the digital data converted by the AD converter.

11. The display device according to claim 10,

wherein the touch is determined when the digital data obtained by converting an integral value of the plurality of integrating circuits for each of the detection electrodes by the AD converter is a value between a first operating point and the most significant bit, and when a difference between the value of the digital data and the first operating point is larger than a first threshold value,

the ghost touch is determined when the digital data obtained by converting an integral value of the plurality of integrating circuits for the detection electrode by the AD converter is a value between a second operating point and the least significant bit, and when a difference between the value of the digital data and the second operating point is larger than a second threshold value.