Liquid crystal display device

Abstract

The present invention relates to a liquid crystal display device, comprising: a first and a second substrate (10, 11); a liquid crystal layer (40) disposed between the first and the second substrate (10, 11); a common electrode (20) disposed on the first substrate (10) and commonly disposed for a plurality of pixels; an integrated circuit (12) for driving the common electrode (20); an FPC (13) connected to the integrated circuit (12); and a resistive element (23) disposed on the FPC (13) having one end connected to the common electrode (20) and the other end connected to a ground terminal (24).

Description

Technical Field

[0001] This invention relates to a liquid crystal display device. Background Technology

[0002] As liquid crystal display devices capable of achieving high contrast and wide viewing angle, there are known liquid crystal display devices that use an electric field in a roughly horizontal direction on a transparent substrate, i.e., liquid crystal display devices that operate in FFS (Fringe-Field Switching) mode, IPS (In-Plain Switching) mode, etc.

[0003] For example, in an FFS-mode liquid crystal display device, a pixel electrode for receiving display signals is formed on one of the two transparent substrates holding the liquid crystal layer, and a common electrode is formed on top of it through an insulating layer. Multiple slits are provided on the common electrode, and a common voltage is supplied to it.

[0004] When a DC voltage is continuously applied to the liquid crystal layer, impurity ions concentrate on one side of the electrode, making it impossible to drive at the intended voltage, resulting in burns and flickering. This degrades the display quality of the liquid crystal display device. Therefore, in liquid crystal display devices, AC driving is used, where the electric field applied to the liquid crystal layer is reversed every unit time.

[0005] In FFS mode, the liquid crystal layer is driven by an electric field applied to the common electrode through a slit passing from the pixel electrode. Along the path of the electric field, the layer structure on the pixel electrode side differs from that on the common electrode side. Charge accumulates at each interface due to the driving action, but the amount of charge accumulated differs between the common electrode side and the pixel electrode side due to the different layer structures.

[0006] Therefore, in FFS mode, even when the liquid crystal layer is driven by AC, a DC component will be generated during continuous driving due to the difference (imbalance) in the charge accumulated on the common electrode side and the pixel electrode side. This DC component can cause burns and flickering.

[0007] Patent Document 1: Japanese Patent Application Publication No. 2009-217211 Summary of the Invention

[0008] This invention provides a liquid crystal display device that can improve display quality.

[0009] According to a first aspect of the present invention, a liquid crystal display device is provided, comprising: a first substrate and a second substrate; a liquid crystal layer disposed between the first substrate and the second substrate; a common electrode disposed on the first substrate and commonly disposed for a plurality of pixels; an integrated circuit for driving the common electrode; an FPC connected to the integrated circuit; and a resistive element disposed on the FPC, having one end connected to the common electrode and another end connected to a ground terminal.

[0010] According to a second aspect of the present invention, a liquid crystal display device is provided, comprising: a first substrate and a second substrate; a liquid crystal layer disposed between the first substrate and the second substrate; a common electrode disposed on the first substrate and commonly disposed for a plurality of pixels; an integrated circuit for driving the common electrode; and a resistive element disposed on the integrated circuit, having one end connected to the common electrode and another end connected to a ground terminal.

[0011] According to a third aspect of the present invention, a liquid crystal display device is provided, comprising: a first substrate and a second substrate; a liquid crystal layer disposed between the first substrate and the second substrate; a common electrode disposed on the first substrate and commonly disposed for a plurality of pixels; an integrated circuit for driving the common electrode; an FPC connected to the integrated circuit; and a switching element disposed on the FPC, having one end connected to the common electrode and another end connected to a ground terminal, wherein the integrated circuit includes a driver for applying a common voltage to the common electrode and a control circuit, wherein the control circuit turns on the switching element during a period when the driver stops operating.

[0012] According to a fourth aspect of the present invention, a liquid crystal display device is provided, comprising: a first substrate and a second substrate; a liquid crystal layer disposed between the first substrate and the second substrate; a common electrode disposed on the first substrate and commonly disposed for a plurality of pixels; an integrated circuit for driving the common electrode; and a switching element disposed on the integrated circuit, having one end connected to the common electrode and another end connected to a ground terminal, wherein the integrated circuit includes a driver for applying a common voltage to the common electrode and a control circuit, wherein the control circuit turns on the switching element during a period when the driver stops operating.

[0013] According to a fifth aspect of the present invention, in a liquid crystal display device of the third or fourth aspect, during the operation of the driver, the control circuit disconnects the switching element.

[0014] According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the liquid crystal display device, the device further comprises: a plurality of pixel electrodes disposed on the first substrate in a manner corresponding to the plurality of pixels; and an insulating layer disposed on the plurality of pixel electrodes, wherein the common electrode is disposed on the insulating layer and has a slit disposed above each of the plurality of pixel electrodes.

[0015] According to a seventh aspect of the present invention, in any one of the first to fifth aspects of the liquid crystal display device, the device further comprises: an insulating layer disposed on the first substrate; and a plurality of pixel electrodes disposed on the insulating layer in a manner corresponding to the plurality of pixels and having slits, wherein the common electrode is disposed between the first substrate and the insulating layer.

[0016] The effects of the invention

[0017] According to the present invention, a liquid crystal display device is provided that can improve display quality. Attached Figure Description

[0018] Figure 1 This is a schematic plan view of a liquid crystal display device according to the first embodiment of the present invention.

[0019] Figure 2 This is a schematic plan view of a liquid crystal display device used to illustrate the common electrode and wiring path.

[0020] Figure 3 yes Figure 2 The cross-sectional view of the FPC shown.

[0021] Figure 4 This is a block diagram of a liquid crystal display device.

[0022] Figure 5 yes Figure 4 The circuit diagram of the pixel array shown.

[0023] Figure 6 It is a planar image of pixels.

[0024] Figure 7 It is along Figure 6 A cross-sectional view of the pixels of the AA′ line.

[0025] Figure 8 It is a timing diagram that explains the operation of a liquid crystal display device.

[0026] Figure 9 This is a block diagram of a liquid crystal display device according to a second embodiment of the present invention.

[0027] Figure 10 This is a schematic plan view of a liquid crystal display device according to a third embodiment of the present invention.

[0028] Figure 11 This is a block diagram of a liquid crystal display device according to the fourth embodiment of the present invention.

[0029] Figure 12 This is a planar view of the pixels according to the fifth embodiment of the present invention.

[0030] Figure 13 It is along Figure 12 A cross-sectional view of the pixels of the AA′ line.

[0031] Explanation of symbols

[0032] 1…Liquid Crystal Display Device, 10…TFT Substrate, 11…CF Substrate, 12…Integrated Circuit, 13…FPC, 13A…Base Film, 13B, 13C…Wiring Layers, 13D, 13E…Cover Film, 14…Display Area, 15…Wiring, 16…Wiring, 20…Common Electrode, 21…Wiring, 22…Wiring, 23…Resistive Element, 24…Ground Terminal, 25…Switching Element, 26…Gate Signal, 30…Pixel Array, 31…Gate Driver, 32…Source Driver, 33…Common Electrode Driver, 34…Voltage Generation Circuit, 35…Control Circuit, 36…TFT, 40…Liquid Crystal Layer, 41…Insulating Layer, 42…Pixel Electrode, 43…Insulating Layer, 44…Slit, 45…Alignment Film, 46…Color Filter, 47…Alignment Film Detailed Implementation

[0033] Hereinafter, embodiments will be described with reference to the accompanying drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of each drawing may not be the same as in reality. Furthermore, even when the drawings represent the same parts, there may be cases where the dimensional relationships and ratios are expressed differently. In particular, the embodiments shown below exemplify apparatus and methods for embodying the technical concept of the present invention, and the technical concept of the present invention is not determined by the shape, structure, or arrangement of the constituent parts. Furthermore, in the following description, elements having the same function and structure are given the same reference numerals, and will be described repeatedly only where necessary.

[0034] [1] First implementation method

[0035] [1-1] Structure of the liquid crystal display device 1

[0036] The liquid crystal display device 1 in this embodiment is a liquid crystal display device in FFS (Fringe-Fields witching) mode. FFS mode is a method of switching uniformly oriented liquid crystal by using an edge electric field.

[0037] Figure 1 This is a schematic plan view of the liquid crystal display device 1 according to the first embodiment of the present invention. Figure 1 The X direction is along one side of the liquid crystal display device 1, and the Y direction is orthogonal to the X direction.

[0038] The liquid crystal display device 1 includes a TFT substrate 10, a CF (color filter) substrate 11, and a liquid crystal layer sealed between the TFT substrate 10 and the CF substrate 11 by a sealing material. Additionally, the liquid crystal display device 1 includes an integrated circuit (IC) 12 and a flexible printed circuit (FPC) 13.

[0039] An integrated circuit 12 is disposed on a TFT substrate 10. The TFT substrate 10 is formed to be slightly larger than the CF substrate 11 in the Y direction. The integrated circuit 12 is disposed in a region of the TFT substrate 10 extending from the CF substrate 11. The integrated circuit 12 is composed of an IC chip. The integrated circuit 12 includes a circuit group for controlling the operation of the liquid crystal display device 1.

[0040] FPC13 is electrically connected to integrated circuit 12. The liquid crystal display device 1 can connect to external devices using FPC13. FPC13 is a printed circuit board, also known as a flexible printed circuit board. FPC13 is a thin, sheet-like printed circuit board on a substrate formed by bonding a thin, flexible, insulating base film to a conductive metal. FPC13 has multiple wirings (not shown).

[0041] The liquid crystal display device 1 has a display area 14 for displaying images. The display area 14 is provided with a plurality of pixels PX arranged in a matrix, a plurality of scan lines, and a plurality of signal lines. The plurality of scan lines are connected to an integrated circuit 12 via a plurality of wirings 15. The plurality of signal lines are connected to the integrated circuit 12 via a plurality of wirings 16. The plurality of wirings 15 and 16 are disposed on a TFT substrate 10.

[0042] Figure 2 This is a schematic plan view illustrating the common electrode 20 and wiring paths of a liquid crystal display device 1. The liquid crystal display device 1 includes a common electrode 20 disposed commonly for a plurality of pixels PX. The common electrode 20 has an area approximately the same as the pixel array. In other words, the common electrode 20 has an area the same as or slightly larger than the display area 14. The common electrode 20 is connected to an integrated circuit 12 via one or more wirings 21. The wirings 21 are disposed on a TFT substrate 10.

[0043] Here, the common electrode 20 is electrically connected to the ground terminal 24 via the resistor element 23, not via the integrated circuit 12. Specifically, the FPC 13 includes the resistor element 23 and the ground terminal 24. The ground terminal 24 is the terminal to which a ground voltage Vss (0V) is supplied. The ground voltage Vss is supplied from an external device connected to the FPC 13. One end of the resistor element 23 is electrically connected to the common electrode 20 via wiring 22. The other end of the resistor element 23 is electrically connected to the ground terminal 24. In this specification, "grounded" and "applied ground voltage Vss" have the same meaning.

[0044] Figure 3 yes Figure 2 The diagram shows a cross-sectional view of the FPC13. The FPC13 includes a base film 13A, wiring layers 13B and 13C, and cover films 13D and 13E. Wiring layer 13B and cover film 13D are sequentially stacked on the base film 13A. Wiring layer 13C and cover film 13E are sequentially stacked below the base film 13A. The multiple layers constituting the FPC13 are bonded together using an adhesive (not shown). The FPC13 may also have more wiring layers. The base film 13A and cover films 13D and 13E are, for example, made of polyimide resin. Wiring layers 13B and 13C include multiple wirings, a resistive element 23, and a ground terminal 24.

[0045] Figure 4 This is a block diagram of a liquid crystal display device 1. The liquid crystal display device 1 includes a pixel array 30, a gate driver (also called a scan line driving circuit) 31, a source driver (also called a signal line driving circuit) 32, a common electrode driver (also called a common electrode driving circuit) 33, a voltage generation circuit 34, and a control circuit 35. Additionally, although not shown in the diagram, the liquid crystal display device 1 includes a backlight disposed on the back of the pixel array 30.

[0046] The pixel array 30 has a plurality of pixels PX configured in a matrix. The pixel array 30 is provided with a plurality of scan lines GL extending along the X direction and a plurality of signal lines SL extending along the Y direction. Pixels PX are arranged in the intersection regions of the scan lines GL and the signal lines SL.

[0047] Gate driver 31 is electrically connected to multiple scan lines GL. Based on control signals from control circuit 35, gate driver 31 sends scan signals to pixel array 30 to turn the switching elements contained in pixel PX on / off.

[0048] The source driver 32 is electrically connected to multiple signal lines SL. The source driver 32 receives control signals and display data from the control circuit 35. Based on the control signals, the source driver 32 sends multiple grayscale signals (driving voltages) corresponding to the display data to the pixel array 30.

[0049] The common electrode driver 33 generates a common voltage Vcom and supplies the common voltage Vcom to the common electrode 20 in the pixel array 30.

[0050] The voltage generating circuit 34 generates various voltages required for the operation of the liquid crystal display device 1 and supplies these voltages to the corresponding circuits.

[0051] The control circuit 35 provides overall control over the operation of the liquid crystal display device 1. The control circuit 35 receives image data and control signals from the outside. Based on the image data, the control circuit 35 generates various control signals and sends these control signals to the corresponding circuits.

[0052] [1-2] Composition of pixel array 30

[0053] Figure 5 yes Figure 4 The circuit diagram of pixel array 30 is shown. Figure 5 The X direction is the row direction of the scan line extension, and the Y direction is the column direction of the signal line extension.

[0054] The pixel array 30 is equipped with multiple scan lines GL1 to GLm and multiple signal lines SL1 to SLn. "m" and "n" are integers greater than or equal to 2.

[0055] The pixel PX includes a switching element 36 and a liquid crystal capacity Clc. The switching element 36 may be a TFT (Thin Film Transistor), specifically an n-channel TFT. Furthermore, the source and drain of the transistor vary depending on the direction of the current flowing through the transistor; however, an example of the transistor's connection state will be described below. It is important to note that the source and drain are not fixed to the names indicated.

[0056] The source of TFT36 is connected to signal line SL, its gate is connected to scan line GL, and its drain is connected to one electrode of the liquid crystal capacity Clc. The liquid crystal capacity Clc consists of a pixel electrode, a common electrode, and a liquid crystal layer. A common voltage Vcom is applied to the other electrode of the liquid crystal capacity Clc by the common electrode driver 33.

[0057] Figure 6 It is a planar view of pixel PX. Figure 7 It is along Figure 6 A cross-sectional view of pixel PX of line AA′.

[0058] As described above, the liquid crystal display device 1 includes: a TFT substrate 10 on which switching elements (TFTs) and pixel electrodes are formed; and a CF substrate 11 disposed opposite to the TFT substrate 10 and on which color filters are formed. The TFT substrate 10 and the CF substrate 11 are each made of a transparent and insulating substrate (e.g., a glass substrate or a resin substrate).

[0059] The liquid crystal layer 40 is sandwiched and filled between the TFT substrate 10 and the CF substrate 11. Specifically, the liquid crystal layer 40 is encapsulated within the display area 14, which is surrounded by the TFT substrate 10, the CF substrate 11, and a sealing material (not shown). The sealing material is formed, for example, by an ultraviolet-curable resin, a thermosetting resin, or an ultraviolet-thermal-curable resin, and is applied to the TFT substrate 10 or the CF substrate 11 during the manufacturing process and then cured by ultraviolet irradiation or heating.

[0060] The liquid crystal material constituting the liquid crystal layer 40 is such that the optical properties change by manipulating the orientation of the liquid crystal molecules according to the applied electric field. In this embodiment, a positive (P-type) nematic liquid crystal with a positive dielectric constant anisotropy is used as the liquid crystal layer 40. The liquid crystal layer 40 is initially horizontally oriented (uniformly oriented). When there is no voltage (no electric field), the liquid crystal molecules are oriented almost horizontally relative to the main surface of the substrate. When a voltage is applied (an electric field is applied), the director of the liquid crystal molecules tilts towards the direction of the electric field.

[0061] First, the configuration of the TFT substrate 10 side will be described. A TFT 36 is provided for each pixel PX on the liquid crystal layer 40 side of the TFT substrate 10. Although the cross-sectional configuration of the TFT 36 is omitted, a general TFT can be used for the TFT 36. The TFT 36 has a gate electrode that functions as a scan line, a gate insulating film disposed on the gate electrode, a semiconductor layer disposed on the gate insulating film, and a source electrode and a drain electrode disposed separately on the semiconductor layer.

[0062] A signal line SL is provided on the TFT substrate 10. The signal line SL is disposed on the same layer as the source electrode of the TFT.

[0063] An insulating layer 41 is provided on TFT36 and signal line SL.

[0064] A pixel electrode 42 is disposed on the insulating layer 41. The pixel electrode 42 extends along the Y direction. The pixel electrode 42 is disposed for each pixel PX and has an area that substantially covers the entire pixel area. The pixel electrode 42 is electrically connected to the drain electrode of the TFT 36 via a contact (not shown).

[0065] An insulating layer 43 is provided on the pixel electrode 42.

[0066] A common electrode 20 is provided on the insulating layer 43. The common electrode 20 is provided commonly for multiple pixels PX. The common electrode 20 has multiple slits (also called openings) 44 for each pixel PX. In this embodiment, a configuration with four slits 44 for each pixel PX is shown as an example. The number of slits 44 can also be one or more. The multiple slits 44 are arranged above the pixel electrode 42. The multiple slits 44 are arranged at equal intervals. The slits 44 extend along the Y direction, just like the pixel electrode 42. The length of the slits 44 in the Y direction is set to be slightly shorter than the length of the pixel electrode 42 in the Y direction.

[0067] An alignment film 45 for controlling the orientation of the liquid crystal layer 40 is provided on the common electrode 20 and the insulating layer 43. The alignment film 45 aligns the liquid crystal molecules horizontally in the initial state of the liquid crystal layer 40. Furthermore, the alignment film 45 is ground to align the long axis of the liquid crystal molecules towards the Y direction.

[0068] Next, the configuration of the CF substrate 11 side will be described.

[0069] A color filter 46 is disposed on the CF substrate 11. The color filter 46 includes a red filter, a green filter, and a blue filter. One of the red filter, green filter, and blue filter is configured for each pixel PX. A black matrix (not shown) is disposed at the boundary of the pixel PX as a light-shielding layer.

[0070] An alignment film 47 is provided on the color filter 46 to control the orientation of the liquid crystal layer 40. The alignment film 47 aligns the liquid crystal molecules horizontally in the initial state of the liquid crystal layer 40. In addition, the alignment film 47 is ground so that the long axis of the liquid crystal molecules is oriented in the Y direction.

[0071] A polarizer (not shown) is provided on the side of the TFT substrate 10 opposite to the liquid crystal layer 40. A polarizer (not shown) is provided on the side of the CF substrate 11 opposite to the liquid crystal layer 40.

[0072] (Examples of materials)

[0073] As scan lines GL and signal lines SL, for example, one of aluminum (Al), molybdenum (Mo), chromium (Cr) and tungsten (W) or an alloy containing one or more of these materials may be used.

[0074] The common electrode 20 and the pixel electrode 42 are made of transparent electrodes, such as ITO (indium tin oxide).

[0075] Transparent insulating materials, such as silicon nitride (SiN), are used as insulating layers 41 and 43.

[0076] [1-3] Actions

[0077] The operation of the liquid crystal display device 1 configured as described above will be explained.

[0078] Figure 8 This is a timing diagram illustrating the operation of the liquid crystal display device 1. Figure 8 The waveforms of scan line GL and signal line SL are shown in the figure.

[0079] Gate driver 31 generates a gate signal that varies between voltage Vg1 and voltage Vg2. Voltage Vg1 is a low-level voltage, and voltage Vg2 is a high-level voltage. For example, voltage Vg1 is a positive voltage, and voltage Vg2 is a negative voltage. Voltages Vg1 and Vg2 are appropriately set according to the specifications of the liquid crystal display device 1. The gate signal from gate driver 31 is supplied to the gate of TFT 36.

[0080] The source driver 32 generates a source signal that varies between voltage Vs1 and voltage Vs2. Voltage Vs1 is a low-level voltage, and voltage Vs2 is a high-level voltage. For example, voltage Vs1 is a positive voltage, and voltage Vs2 is a negative voltage. Voltages Vs1 and Vs2 are appropriately set according to the specifications of the liquid crystal display device 1. Figure 8 The average voltage Vav is the average voltage of voltages Vs1 and Vs2 (also known as the intermediate voltage). The source signal from the source driver 32 is supplied to the pixel electrode 42 via the TFT 36.

[0081] The common electrode driver 33 generates a common voltage Vcom and supplies this common voltage Vcom to the common electrode 20. The common voltage Vcom is used as a reference voltage and is a voltage higher than voltage Vs1 and lower than voltage Vs2. For example, the common voltage Vcom is a voltage lower than the average voltage Vav. For example, the common voltage Vcom is a negative voltage. The common voltage Vcom is appropriately set according to the specifications of the liquid crystal display device 1.

[0082] At time t0, the source driver 32 applies a voltage Vs2 to the signal line SL.

[0083] At time t1, gate driver 31 applies voltage Vg2 to scan line GL. As a result, TFT 36 is turned on, and the potential of signal line SL is applied to pixel electrode 42.

[0084] At time t2, gate driver 31 applies voltage Vg1 to scan line GL. As a result, TFT 36 is turned off.

[0085] At time t3, the source driver 32 applies a voltage Vs1 to the signal line SL.

[0086] At time t4, gate driver 31 applies voltage Vg2 to scan line GL. As a result, TFT 36 is turned on, and the potential of signal line SL is applied to pixel electrode 42.

[0087] At time t5, gate driver 31 applies voltage Vg1 to scan line GL. As a result, TFT 36 is turned off.

[0088] Then, the liquid crystal display device 1 repeatedly performs the same operation as described above. In this way, AC driving (also called phase inversion driving) of the liquid crystal display device 1 is achieved. By performing AC driving, liquid crystal degradation can be suppressed. The period of AC driving can be arbitrarily set.

[0089] Next, the orientation of the liquid crystal layer 40 will be explained.

[0090] The off state is when no electric field is applied to the liquid crystal layer 40, and the pixel electrode 42 is subjected to the same common voltage Vcom as the common electrode 20 or the ground voltage Vss (0V). The on state is when an electric field is applied to the liquid crystal layer 40, and the pixel electrode 42 is subjected to a positive voltage or a negative voltage different from the common voltage Vcom.

[0091] In the off state, the liquid crystal molecules are set to their initial state, i.e., the long axis of the liquid crystal molecules is oriented in the Y direction. The Y direction is the same as the grinding direction of the alignment film. In the off state, the liquid crystal display device 1 displays, for example, black.

[0092] In the ON state, the liquid crystal layer 40 is applied Figure 7 The electric field is indicated by the dashed arrow. When viewed from above, the liquid crystal molecules rotate in a direction tilted relative to the Y direction. Therefore, the liquid crystal display device 1 can control the amount of incident light transmitted, that is, it can change the transmittance of the liquid crystal display device 1. In the on state, the liquid crystal display device 1 performs color display.

[0093] Here, as Figure 2 As shown, in this embodiment, the common electrode 20 is connected to the ground terminal 24 via the resistor element 23. That is, the common electrode 20 is grounded via the resistor element 23.

[0094] During the period when the common electrode driver 33 is not operating, the charge accumulated on the common electrode 20 and its interface is discharged to the ground terminal 24 via the resistive element 23. "Common electrode driver 33 operating" means that the common electrode driver 33 applies a common voltage Vcom to the common electrode 20. "Common electrode driver 33 stopping operating" means that the common electrode driver 33 does not apply a common voltage Vcom to the common electrode 20.

[0095] During the operation of the common electrode driver 33, the resistive element 23 functions to suppress the current flowing from the common electrode 20 to the ground terminal 24. The resistance value of the resistive element 23 is set based on the driving capability of the common electrode driver 33. The greater the driving capability of the common electrode driver 33, the greater the resistance value of the resistive element 23 becomes. During the application of the common voltage Vcom to the common electrode 20 by the common electrode driver 33, the resistive element 23 is set to a relatively large resistance value to minimize interference with the voltage application operation of the common electrode driver 33.

[0096] exist Figure 7 The focus is on the path of the electric field applied to the liquid crystal layer 40. On the common electrode 20 side, there are interfaces between the common electrode 20 and the alignment film 45, and between the alignment film 45 and the liquid crystal layer 40. On the pixel electrode 42 side, there are interfaces between the pixel electrode 42 and the insulating layer 43, between the insulating layer 43 and the alignment film 45, and between the alignment film 45 and the liquid crystal layer 40. Charge accumulates at each interface due to the driving action, but the amount of charge accumulated differs between the common electrode 20 side and the pixel electrode 42 side due to the different layer structures.

[0097] A direct current (DC) component is generated due to the imbalance between the charge accumulated on the common electrode 20 side and the charge accumulated on the pixel electrode 42 side. The DC component is a certain DC voltage applied to an alternating current voltage. This DC component can cause burns and flashes.

[0098] However, in this embodiment, the charge accumulated on the multiple layers disposed on the TFT substrate 10 and their interfaces can be discharged to the ground terminal 24 via the resistive element 23.

[0099] [1-4] Effects of the first embodiment

[0100] In the first embodiment, the FFS mode liquid crystal display device 1 includes a TFT substrate 10, a pixel electrode 42 disposed on the TFT substrate 10, and a common electrode 20 disposed above the pixel electrode 42. Then, the common electrode 20 is connected to the ground terminal 24 via wiring 22 and a resistor element 23 without going through the integrated circuit 12.

[0101] Therefore, according to the first embodiment, the charge accumulated on the multiple layers provided on the TFT substrate 10 and their interfaces can be discharged to the ground terminal 24 via the resistive element 23. This reduces the DC component generated in the liquid crystal display device 1. Consequently, burn-in and flickering in the liquid crystal display device 1 can be reduced. Thus, a liquid crystal display device with improved display quality can be realized.

[0102] Furthermore, according to the configuration of the first embodiment, the unwanted charge accumulated in the liquid crystal display device 1 can be discharged more quickly using the resistive element 23 and the grounding terminal 24.

[0103] Furthermore, the resistor element 23 and the ground terminal 24 are provided on the FPC 13 connected to the integrated circuit 12. Thus, without changing the configuration of the integrated circuit 12, it is possible to discharge unwanted charges accumulated in the liquid crystal display device 1.

[0104] [2] Second implementation method

[0105] In the second embodiment, a resistive element 23 is provided within the integrated circuit 12. Then, the charge accumulated on the multiple layers provided on the TFT substrate 10 and their interfaces is discharged to the ground terminal via the resistive element 23.

[0106] Figure 9 This is a block diagram of a liquid crystal display device 1 according to a second embodiment of the present invention. A common electrode 20 is connected to a common electrode driver 33 via wiring 21. The common electrode driver 33 supplies a common voltage Vcom to the common electrode 20 via wiring 21.

[0107] Integrated circuit 12 includes a resistor element 23 and a ground terminal 24. The ground terminal 24 is a terminal supplied with a ground voltage Vss (0V). One end of the resistor element 23 is electrically connected to wiring 21. The other end of the resistor element 23 is electrically connected to the ground terminal 24.

[0108] In the second embodiment, during the period when the common electrode driver 33 stops operating, the charge accumulated on the common electrode 20 and at its interface is discharged to the ground terminal 24 via the resistive element 23. This reduces the DC component generated in the liquid crystal display device 1. Consequently, burn-in and flickering in the liquid crystal display device 1 can be reduced.

[0109] [3] Third implementation method

[0110] In the third embodiment, a switching element is used to switch the connection between the common electrode 20 and the ground terminal 24.

[0111] Figure 10 This is a schematic plan view of the liquid crystal display device 1 according to the third embodiment of the present invention. Figure 2 same, Figure 10 The representation is centered on the common electrode 20.

[0112] FPC13 includes a switching element 25 and a ground terminal 24. One end of the switching element 25 is electrically connected to a common electrode 20 via wiring 22. The other end of the switching element 25 is electrically connected to the ground terminal 24. The switching element 25 can use FET (Field Effect Transistor) and TFT, etc. The switching element 25 is disposed within wiring layers 13B and 13C of FPC13.

[0113] The switching action of the switching element 25 is controlled by the control circuit 35. Specifically, the control circuit 35 supplies a gate signal 26 to the gate of the switching element 25. The control circuit 35 is included in... Figure 10 Integrated circuit 12. Wiring for gate signal 26 is provided within FPC 13.

[0114] During the operation of the common electrode driver 33, the control circuit 35 disconnects the switching element 25. Consequently, the common electrode driver 33 applies a common voltage Vcom to the common electrode 20.

[0115] During the period when the common electrode driver 33 is not operating, the control circuit 35 turns on the switching element 25. As a result, the charge accumulated on the common electrode 20 and its interface is discharged to the ground terminal 24 via the switching element 25.

[0116] This reduces the DC component generated in the liquid crystal display device 1. Consequently, it reduces burn-in and flickering in the liquid crystal display device 1.

[0117] In addition, in the above embodiment, the switching element 25 is disposed on the FPC 13, but the switching element 25 may also be disposed in the middle of the wiring 22. For example, the switching element 25 may also be disposed on the TFT substrate 10.

[0118] Alternatively, the aforementioned resistor element 23 can be provided between the switching element 25 and the grounding terminal 24. In this case, the resistor element 23 has the function of adjusting the current flowing between the common electrode 20 and the grounding terminal 24.

[0119] [4] Fourth implementation method

[0120] In the fourth embodiment, the switching element 25 and the grounding terminal 24 are disposed within the integrated circuit 12.

[0121] Figure 11 This is a block diagram of a liquid crystal display device 1 according to a fourth embodiment of the present invention. The common electrode 20 is connected to the common electrode driver 33 via wiring 21.

[0122] Integrated circuit 12 includes a switching element 25 and a ground terminal 24. One end of the switching element 25 is electrically connected to wiring 21. The other end of the switching element 25 is electrically connected to the ground terminal 24. A gate signal 26 is supplied to the gate of the switching element 25 from the control circuit 35.

[0123] During the operation of the common electrode driver 33, the control circuit 35 disconnects the switching element 25. Consequently, the common electrode driver 33 applies a common voltage Vcom to the common electrode 20.

[0124] During the period when the common electrode driver 33 is not operating, the control circuit 35 turns on the switching element 25. As a result, the charge accumulated on the common electrode 20 and at the interface of the common electrode 20 is discharged to the ground terminal 24 via the switching element 25.

[0125] This reduces the DC component generated in the liquid crystal display device 1. Consequently, it reduces burn-in and flickering in the liquid crystal display device 1.

[0126] Alternatively, the aforementioned resistor element 23 can be provided between the switching element 25 and the grounding terminal 24.

[0127] [5] Fifth implementation method

[0128] The fifth embodiment is another configuration example of the pixel PX. In the fifth embodiment, the common electrode 20 is disposed on the lower side, and the pixel electrode 42 is disposed on the upper side.

[0129] Figure 12 This is a plan view of pixel PX according to the fifth embodiment of the present invention. Figure 13 It is along Figure 12 A cross-sectional view of pixel PX of line AA′.

[0130] A common electrode 20 is provided on the insulating layer 41. The common electrode 20 is provided commonly for multiple pixels PX. The common electrode 20 has an area that is the same as or slightly larger than the display area 14. Unlike the first embodiment, the common electrode 20 is planar and does not have a slit.

[0131] An insulating layer 43 is provided on the common electrode 20.

[0132] A pixel electrode 42 is disposed on an insulating layer 43. The pixel electrode 42 extends along the Y direction. The pixel electrode 42 is disposed for each pixel PX and has an area that substantially covers the entire pixel region. The pixel electrode 42 has a plurality of slits (also referred to as openings) 44. In this embodiment, a configuration in which the pixel electrode 42 has four slits 44 is shown as an example. The number of slits 44 may also be one or more. The plurality of slits 44 are arranged at equal intervals. The slits 44 extend along the Y direction to near both ends of the pixel electrode 42.

[0133] The pixel electrode 42 is electrically connected to the drain electrode of the TFT 36 via a contact (not shown). Additionally, an opening (not shown) is provided on the common electrode 20 for the contact to pass through.

[0134] An alignment film 45 for controlling the alignment of the liquid crystal layer 40 is provided on the pixel electrode 42 and the insulating layer 43.

[0135] The other components are the same as in the first embodiment. Furthermore, the second to fourth embodiments can also be applied to the fifth embodiment.

[0136] In the above embodiments, the liquid crystal display device 1 in FFS mode was described as an example, but this embodiment can also be applied to liquid crystal modes other than FFS mode, such as IPS (In-Plane Switching) mode, vertical alignment (VA) mode, and TN (Twisted Nematic) mode.

[0137] This invention is not limited to the embodiments described above, and various modifications can be made during implementation without departing from its spirit. Furthermore, the embodiments can be appropriately combined, resulting in combined effects. Moreover, since the above embodiments encompass various inventions, various inventions can be extracted through combinations selected from a plurality of disclosed constituent elements. For example, if deleting several constituent elements from all the constituent elements shown in the embodiments can solve the problem and achieve the desired effect, the configuration in which those constituent elements are deleted can also be extracted as an invention.

Claims

1. A liquid crystal display device, comprising: First and second substrates; A liquid crystal layer is disposed between the first and second substrates. A common electrode is disposed on the first substrate and is disposed in common to multiple pixels; An integrated circuit is disposed on the first substrate and drives the common electrode. The FPC is configured to connect the aforementioned integrated circuit to an external device; and A resistive element, disposed in the aforementioned FPC, has one end connected to the aforementioned common electrode and another end connected to the ground terminal. The aforementioned resistive element is directly connected to the aforementioned common electrode without going through the aforementioned integrated circuit.

2. The liquid crystal display device as claimed in claim 1, wherein, The aforementioned FPC includes a base film, a cover film, and a wiring layer disposed between the base film and the cover film. The aforementioned wiring layer includes multiple wirings, the aforementioned resistive elements, and the aforementioned grounding terminal.

3. A liquid crystal display device, comprising: First and second substrates; A liquid crystal layer is disposed between the first and second substrates. A common electrode is disposed on the first substrate and is disposed in common to multiple pixels; An integrated circuit is disposed on the first substrate and drives the common electrode. The FPC is configured to connect the aforementioned integrated circuit to an external device; and A switching element, disposed in the aforementioned FPC, has one end connected to the aforementioned common electrode and another end connected to the ground terminal. The aforementioned integrated circuit includes a driver that applies a common voltage to the common electrode, and a control circuit. During the period when the aforementioned driver stops operating, the aforementioned control circuit turns on the aforementioned switching element. The aforementioned switching element is directly connected to the aforementioned common electrode without going through the aforementioned integrated circuit.

4. The liquid crystal display device as claimed in claim 3, wherein, The aforementioned FPC includes a base film, a cover film, and a wiring layer disposed between the base film and the cover film. The aforementioned wiring layer includes multiple wirings, the aforementioned switching elements, and the aforementioned grounding terminal.

5. The liquid crystal display device as claimed in claim 3 or 4, wherein, During the operation of the aforementioned driver, the aforementioned control circuit disconnects the aforementioned switching element.

6. The liquid crystal display device according to any one of claims 1 to 4, further comprising: Multiple pixel electrodes are disposed on the first substrate in a manner corresponding to the aforementioned multiple pixels; and An insulating layer is disposed on the aforementioned pixel electrodes. The aforementioned common electrode is disposed on the aforementioned insulating layer and has a slit disposed above each of the aforementioned plurality of pixel electrodes.

7. The liquid crystal display device according to any one of claims 1 to 4, further comprising: An insulating layer is disposed on the first substrate; and Multiple pixel electrodes are disposed on the insulating layer in a manner corresponding to the aforementioned multiple pixels, and have slits. The aforementioned common electrode is disposed between the aforementioned first substrate and the aforementioned insulating layer.

Images