Display device

• US 10,444,906 B2
• Filed: 04/11/2019
• Issued: 10/15/2019
• 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:
  US16/381,087
• Publication Number:
  US 20190235700A1
• Time in Patent Office: 187 Days
• 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 having a plurality of pixels arranged in a matrix, and common electrodes divided into M blocks when M is an integral number of 2 or more (M≥

2);

a driver circuit applying a touch panel scanning voltage to the common electrodes; and

a detector circuit including an averaging filter,

wherein the common electrodes of each of the M divided blocks are shared with the respective pixels,

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 determines;

in a normal touch detection process, the touch event applying the touch panel scanning voltage to the common electrodes of each of the M divided blocks;

in a ghost touch process, a ghost touch unidentifiable event without reporting a touch position, and a ghost touch event reporting a ghost touch position when the averaging filter output a ghost touch data.

2. The display device according to claim 1,

wherein the detector circuit includes an AD converter,

wherein the AD converter converts an analog signal obtained by the touch panel scanning voltage to a digital data, and

wherein the touch event is determined by comparing the digital data and a first threshold value for determining the touch event of the normal touch detection process.

3. The display device according to claim 2,

wherein a first threshold value is different from a second threshold value for determining the ghost touch event of the ghost touch detection process.

4. The display device according to claim 2,

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.

5. The display device according to claim 4,

wherein the digital data 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.

6. The display device according to claim 4,

wherein the ghost touch event is determined when the digital data 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.

7. 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.

8. A display device comprising:

a display panel having a plurality of pixels arranged in a matrix, and common electrodes divided into M blocks when M is an integral number of 2 or more (M_2);

a driver circuit applying a touch panel scanning voltage to the common electrodes; and

a detector circuit including an integrating circuit, an AD converter, and an averaging filter,

wherein the common electrodes of each of the M divided blocks are shared with the respective pixels,

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

wherein the integrating circuit includes a reference voltage input terminal and outputs an analog touch signal of the display panel,

wherein the AD converter converts an output voltage of the integrating circuit into digital data,

wherein the detector circuit determines;

in a normal touch detection process, the touch event applying the touch panel scanning voltage to the common electrodes of each of the M divided blocks;

in a ghost touch process, a ghost touch unidentifiable event without reporting a touch position, and a ghost touch event reporting a ghost touch position when the averaging filter output a ghost touch data,

wherein the 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 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, and

wherein the first operating point is digital data which is converted the reference voltage.

9. The display device according to claim 8,

wherein the 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 second operating point that is the most significant bit in the digital data converted by the AD converter.

10. The display device according to claim 8,

wherein the touch event is determined when the digital data obtained by converting an output voltage of the integrating circuit 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.

11. The display device according to claim 8,

wherein the ghost touch event is determined when the digital data obtained by converting the integrating circuit 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.