LIQUID CRYSTAL DISPLAY DEVICE

• US 20140085235A1
• Filed: 09/12/2013
• Published: 03/27/2014
• Est. Priority Date: 09/24/2012
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: TOKITA, Masahiro, TSUYUZAKI, Seiichi
• Granted Patent: US 9,383,862 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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 liquid crystal display device comprising a liquid crystal display panel having liquid crystal sandwiched between a first substrate and a second substrate, and a plurality of pixels arranged in a matrix,

wherein the liquid crystal display panel includes:

a plurality of detection electrodes of a touch panel arranged on the second substrate;

pixel electrodes arranged in the respective pixels;

counter electrodes arranged in the respective pixels and divided into M blocks when M is an integral number of 2 or more (M≧

2);

a driver circuit that applies a counter voltage and a touch panel scanning voltage to the counter electrodes of each of the M divided blocks; and

a detector circuit that detects whether a touch is present, or not, on the basis of a current flowing in the plurality of detection electrodes,

wherein the counter 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 the scanning electrodes of the touch panel,

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

wherein the detector circuit includes;

a first unit that detects whether the touch is present, or not, on the basis of a current flowing in the plurality of detection electrodes when the touch panel scanning voltage is applied to the counter electrodes of each of the M 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.

2. The liquid crystal display device according to claim 1,

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,

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

wherein the first unit determines that a touch is present when a value of the digital data obtained by converting an integral value of the plurality of integrating circuits for each of the counter electrodes of each of the M divided blocks 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 given first threshold value, and determines that the touch is absent in other cases, with 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 as the first operating point, and

wherein the second unit determines that noise is present when a value of the digital data obtained by converting an integral value of the plurality of integrating circuits for the fictional (M+1)^th counter 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 given second threshold value, with the most significant bit in the digital data converted by the AD converter as the second operating point.

3. The liquid crystal 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.

4. The liquid crystal display device according to claim 2, further comprising:

a third unit that identifies the fictional touch generated by noise when the noise is detected by the second unit,

wherein the third unit allows the digital data obtained by converting the integral value of the integrating circuits corresponding to the detection electrode in which the noise is detected by the second unit for each of the counter electrodes of each of the M divided blocks by the AD converter to pass through an averaging filter, and determines an electrode having a maximum data value among the data that has passed through the averaging filter as an actual touch electrode, and identifies, as the fictional touch electrode, an electrode in which a data value is a value between the maximum value and the least significant bit, and a difference between the data value and the maximum value is larger than a given third threshold value.

5. A liquid crystal display device including a liquid crystal display panel having liquid crystal sandwiched between a first substrate and a second substrate, and a plurality of pixels arranged in a matrix,

wherein the liquid crystal display panel includes:

a plurality of detection electrodes of a touch panel arranged on the second substrate;

pixel electrodes arranged in the respective pixels;

counter electrodes arranged in the respective pixels and divided into M blocks when M is an integral number of 2 or more (M≧

2);

a driver circuit that applies a counter voltage and a touch panel scanning voltage to the counter electrodes of each of the M divided blocks; and

a detector circuit that detects whether a touch is present, or not, on the basis of a current flowing in the plurality of detection electrodes,

wherein the counter 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 the scanning electrodes of the touch panel,

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

wherein the detector circuit includes;

a first unit that detects whether the touch is present, or not, on the basis of a current flowing in the plurality of detection electrodes when the touch panel scanning voltage is applied to the counter electrodes of each of the M divided blocks;

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; and

a third unit that identifies a fictional touch caused by noise when the noise is detected by the second unit,

wherein in a touch detecting process, a normal touch position detecting process is executed when the noise is not detected by the second unit,

wherein when the noise is detected by the second unit, if the fictional touch caused by the noise can be identified by the third unit, a touch position detecting process is executed with reference to the fictional touch identified by the third unit, and

wherein when the noise is detected by the second unit, if the fictional touch caused by the noise cannot be identified by the third unit, the touch position detecting process is not executed.

6. The liquid crystal display device according to claim 5,

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,

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

wherein the first unit determines that a touch is present when a value of the digital data obtained by converting an integral value of the plurality of integrating circuits for each of the counter electrodes of each of the M divided blocks 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 given first threshold value, and determines that the touch is absent in other cases, with 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 as the first operating point,

wherein the second unit determines that noise is present when a value of the digital data obtained by converting an integral value of the plurality of integrating circuits for the fictional (M+1)^th counter 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 given second threshold value, with the most significant bit in the digital data converted by the AD converter as the second operating point, and

wherein the third unit allows the digital data obtained by converting the integral value of the integrating circuits corresponding to the detection electrode in which the noise is detected by the second unit for each of the counter electrodes of each of the M divided blocks by the AD converter to pass through an averaging filter, and determines an electrode having a maximum data value among the data that has passed through the averaging filter as an actual touch electrode, and identifies, as the fictional touch electrode, an electrode in which a data value is a value between the maximum value and the least significant bit, and a difference between the data value and the maximum value is larger than a given third threshold value.