Liquid crystal display device

Abstract

The liquid crystal display device of the embodiment includes a first substrate, a second substrate and a liquid crystal layer. The first substrate includes: a first common electrode; a second common electrode located between the first common electrode and the liquid crystal layer in the thickness direction of the first substrate; a first pixel electrode located between the first common electrode and the second common electrode in the thickness direction, and having a pair of first side edges arranged in the first direction. The second common electrode includes: a first main body and a second main body extending in the first direction and arranged in the second direction; a first branch extending from the second main body toward the first main body. The first pixel electrode is located between the first main body and the second main body. The first branch overlaps with the first pixel electrode between the pair of first side edges. The width of the first pixel electrode between the pair of first side edges decreases as it approaches the second main body.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based upon and claims the benefit of priority of Japanese patent application No. 2021-093665 filed on June 3, 2021, and the entire contents of the above-mentioned Japanese patent application are incorporated herein by reference. Technical Field

[0003] An embodiment of the present invention relates to a liquid crystal display device. Background Art

[0004] As an example of a display device, an IPS (In-Plane-Switching) mode liquid crystal display device is known. In an IPS mode liquid crystal display device, pixel electrodes and common electrodes are provided on one of a pair of substrates that are opposed to each other with a liquid crystal layer interposed therebetween, and the orientation of liquid crystal molecules in the liquid crystal layer is controlled by the lateral electric field generated between these electrodes. In addition, in the IPS mode, an FFS (Fringe Field Switching) mode liquid crystal display device in which the pixel electrodes and the common electrode are arranged on different layers has been put into practical use. In this liquid crystal display device, the orientation of liquid crystal molecules is controlled by the fringe electric field generated between a pair of electrodes.

[0005] On the other hand, Japanese Patent Application Publication No. 2018-116184 discloses a liquid crystal display device that increases the response speed by periodically forming a region in each pixel where liquid crystal molecules do not rotate. Hereinafter, the structure of such a liquid crystal display device is referred to as a high-speed response mode.

[0006] In the high-speed response mode, it is necessary to form a comb-teeth-shaped electrode pattern at a narrow pitch in each pixel. When the liquid crystal display device is made more precise, the comb-teeth-shaped electrode pattern may short-circuit. Summary of the invention

[0007] A liquid crystal display device according to one embodiment includes: a first substrate; a second substrate facing the first substrate; and a liquid crystal layer between the first substrate and the second substrate. The first substrate includes: a first common electrode to which a common voltage is applied; a second common electrode located between the first common electrode and the liquid crystal layer in the thickness direction of the first substrate and to which the common voltage is applied; and a first pixel electrode located between the first common electrode and the second common electrode in the thickness direction and having a pair of first side edges arranged in a first direction. The second common electrode includes: a first main body and a second main body, each extending in the first direction and arranged in a second direction intersecting the first direction; and a first branch portion extending from the second main body toward the first main body. The first pixel electrode is located between the first main body and the second main body. The first branch portion overlaps with the first pixel electrode between the pair of first side edges. Furthermore, the width of the first pixel electrode between the pair of first side edges decreases as it approaches the second main body.

[0008] With such a structure, a liquid crystal display device capable of achieving higher definition can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a perspective view schematically showing a configuration example of the liquid crystal display device according to the first embodiment.

[0010] Figure 2 This is a diagram schematically showing an example of an equivalent circuit of the liquid crystal display device according to the first embodiment.

[0011] Figure 3 is a schematic cross-sectional view of the display panel according to the first embodiment.

[0012] Figure 4 is another schematic cross-sectional view of the display panel of the first embodiment.

[0013] Figure 5 This is a top view showing a model for explaining the operating principle of the high-speed response mode.

[0014] Figure 6 It means in Figure 5 A top view of the state in which an electric field is formed in the model.

[0015] Figure 7 It is a top view showing another model for explaining the operating principle of the high-speed response mode.

[0016] Figure 8 It means in Figure 7 A top view of the state in which an electric field is formed in the model.

[0017] Fig. 9 This is a schematic plan view of the first common electrode, the second common electrode, and the pixel electrode according to the first embodiment.

[0018] Fig.10 It is a schematic plan view showing a more detailed structure of a sub-pixel applicable to the first embodiment.

[0019] Fig.11 This is a schematic plan view of another example of a sub-pixel according to the first embodiment.

[0020] Fig.12 It is a schematic plan view of a sub-pixel according to the second embodiment.

[0021] Fig.13 It is a schematic plan view of a sub-pixel according to the third embodiment.

[0022] Fig.14 It is a schematic plan view of a sub-pixel according to the fourth embodiment. DETAILED DESCRIPTION

[0023] Several embodiments will be described below with reference to the drawings.

[0024] In addition, the disclosure is only an example, and for those skilled in the art, the contents that can be easily thought of for appropriate changes to maintain the main purpose of the invention are of course included in the scope of the present invention. In addition, in order to make the description clearer, the drawings sometimes schematically show the width, thickness, shape, etc. of each part compared with the actual method, but it is only an example and does not limit the interpretation of the present invention. In addition, in this specification and each figure, the same reference figure numerals are marked for the structural elements that perform the same or similar functions as the above-mentioned structural elements related to the figures that have appeared, and repeated detailed descriptions are sometimes appropriately omitted.

[0025] In each embodiment, a liquid crystal display device is disclosed as an example of an electronic device. The liquid crystal display device can be used in various devices such as a VR (Virtual Reality) browser, a smart phone, a tablet terminal, a mobile phone terminal, a personal computer, a television receiver, a car device, a game console, and a wearable terminal.

[0026] [First embodiment]

[0027] Figure 1It is a stereoscopic diagram schematically showing a structural example of a liquid crystal display device DSP (hereinafter referred to as the display device DSP) of the first embodiment. The first direction X, the second direction Y and the third direction Z shown in the figure are orthogonal to each other, but may also intersect at an angle other than 90 degrees. The first direction X and the second direction Y correspond to directions parallel to the main surface of the substrate constituting the liquid crystal display device (hereinafter referred to as the display device) DSP. The third direction Z corresponds to the thickness direction of the display device DSP and its structural elements. In this specification, the direction from the first substrate SUB1 toward the second substrate SUB2 is referred to as the "upper side" (or simply upper), and the direction from the second substrate SUB2 toward the first substrate SUB1 is referred to as the "lower side" (or simply lower). In the case of "the second layer above the first layer" and "the second layer below the first layer", the second layer may be in contact with the first layer or may be separated from the first layer. In addition, the situation of observing the display device DSP and its structural elements parallel to the third direction Z is referred to as a top view.

[0028] The display device DSP includes: a display panel PNL; a lighting device BL facing the display panel PNL; a driver IC4 driving the display panel PNL; a control module 5 controlling the operation of the display panel PNL and the lighting device BL; a flexible circuit board FPC1; and a flexible circuit board FPC2.

[0029] exist Figure 1 In the example, the shape of the display panel PNL in a plan view is a rectangular shape having short sides parallel to the first direction X and long sides parallel to the second direction Y. The planar shape of the display panel PNL may be, for example, a square, a perfect circle, an ellipse or other shapes.

[0030] The display panel PNL includes: a first substrate SUB1 ; a second substrate SUB2 facing the first substrate SUB1 ; and a liquid crystal layer (a liquid crystal layer LC to be described later) located between the substrates SUB1 and SUB2 .

[0031] The display panel PNL includes a display area DA and a non-display area NDA. The display area DA is an area where an image is displayed. The non-display area NDA is an area where an image is not displayed. Figure 1 In the example of FIG. 1 , the non-display area NDA surrounds the display area DA. The non-display area NDA may also be referred to as a peripheral area or a frame area. The display panel PNL includes, for example, a plurality of pixels PX arranged in a matrix in the display area DA.

[0032] The driver IC4 is located in the non-display area NDA. Figure 1In the example, the driver IC4 is mounted on the mounting portion MT of the first substrate SUB1. The mounting portion MT is a portion of the first substrate SUB1 that does not overlap with the second substrate SUB2. In addition, the driver IC4 may be mounted on other locations such as the flexible circuit substrate FPC1.

[0033] The flexible circuit board FPC1 electrically connects the display panel PNL and the control module 5. The flexible circuit board FPC2 electrically connects the lighting device BL and the control module 5. The flexible circuit board FPC1 transmits a signal output from the control module 5 to the display panel PNL. The flexible circuit board FPC2 transmits a signal output from the control module 5 to the lighting device BL.

[0034] Figure 2 1 is a diagram schematically showing an example of an equivalent circuit of a display device DSP. The display device DSP includes: a first driver DR1; a second driver DR2; a plurality of scanning lines G connected to the first driver DR1; and a plurality of signal lines S connected to the second driver DR2. Each scanning line G extends in the display area DA along the first direction X and is arranged at intervals in the second direction Y. Each signal line S extends in the display area DA along the second direction Y and is arranged at intervals in the first direction X and intersects each scanning line G.

[0035] The pixel PX includes a plurality of sub-pixels SP. For example, in the present embodiment, it is assumed that one pixel PX includes a red sub-pixel SPR, a green sub-pixel SPG, and a blue sub-pixel SPB. However, the pixel PX may also include a sub-pixel SP that displays white, or may include a plurality of sub-pixels SP corresponding to the same color. In addition, a sub-pixel is sometimes referred to as a pixel.

[0036] exist Figure 2 In the embodiment, the sub-pixel SP corresponds to a region divided by two scanning lines G adjacent to each other in the first direction X and two signal lines S adjacent to each other in the second direction Y. A switching element SW and a pixel electrode PE are provided for each sub-pixel SP. In addition, a common electrode CE is formed over a plurality of sub-pixels SP. A common voltage is applied to the common electrode CE. The switching element SW is composed of, for example, a thin film transistor (TFT), and is connected to the scanning line G, the signal line S, and the pixel electrode PE.

[0037] The scanning line G is connected to the switching element SW in each of the sub-pixels SP arranged in the first direction X. The signal line S is connected to the switching element SW in each of the sub-pixels SP arranged in the second direction Y. For example, a holding capacitor is formed between the common electrode CE and the pixel electrode PE.

[0038] The first driver DR1 sequentially supplies scanning signals to each scanning line G. The second driver DR2 selectively supplies image signals to the signal line S. When a scanning signal is supplied to the scanning line G corresponding to a certain switching element SW, and an image signal is supplied to the signal line S connected to the switching element SW, a pixel voltage corresponding to the image signal is applied to the pixel electrode PE. At this time, the alignment of the liquid crystal molecules of the liquid crystal layer LC changes from the initial alignment state to which no voltage is applied, by the electric field generated between the pixel electrode PE and the common electrode CE. Through such an action, an image is displayed in the display area DA.

[0039] Figure 3 FIG. 1 is a schematic cross-sectional view of the display panel PNL of this embodiment. Figure 3 In the cross section shown in the figure, the first substrate SUB1 includes a transparent insulating base material 10, insulating layers 11, 12, 13, 14, 15, 16, a first alignment film 17, a signal line S, a common electrode CE, and a pixel electrode PE.

[0040] The insulating substrate 10 is formed of, for example, glass or plastic. The insulating layers 11, 12, 13, 14, 15, and 16 are stacked in this order in the third direction Z. The insulating layers 11, 12, 13, 15, and 16 are formed of, for example, inorganic materials such as silicon nitride and silicon oxide. The insulating layer 14 is formed of, for example, an organic material such as acrylic resin.

[0041] The signal line S is disposed on the insulating layer 13 and covered by the insulating layer 14. In this embodiment, the common electrode CE includes a first common electrode CE1 and a second common electrode CE2 located between the first common electrode CE1 and the liquid crystal layer LC in the third direction Z. A common voltage is applied to each of the first common electrode CE1 and the second common electrode CE2.

[0042] The first common electrode CE1 is disposed on the insulating layer 14 and is covered by the insulating layer 15 . The second common electrode CE2 is disposed on the insulating layer 16 and is covered by the first alignment film 17 .

[0043] The pixel electrode PE is disposed on the insulating layer 15 and is covered by the insulating layer 16. That is, the pixel electrode PE is located between the first common electrode CE1 and the second common electrode CE2 in the third direction Z.

[0044] exist Figure 3 In the cross section of , the first common electrode CE1 , the second common electrode CE2 , and the pixel electrode PE overlap in the third direction Z. The first common electrode CE1 , the second common electrode CE2 , and the pixel electrode PE are formed of a transparent conductive material such as ITO (Indium Tin Oxide).

[0045] The second substrate SUB2 includes a transparent insulating base material 20, a light shielding layer 21, a color filter 22, a protective layer 23, and a second alignment film 24. The insulating base material 20 is formed of, for example, glass or plastic.

[0046] The light shielding layer 21 and the color filter 22 are disposed under the insulating substrate 20 and covered by a protective layer 23. The protective layer 23 is covered by a second alignment film 24. The first alignment film 17 and the second alignment film 24 align liquid crystal molecules included in the liquid crystal layer LC in an initial alignment direction described later.

[0047] The light shielding layer 21 is disposed at the boundary between the sub-pixels SP. The light shielding layer 21 has an opening OP in each sub-pixel SP. The opening OP overlaps with the color filter 22 of the color corresponding to the sub-pixel SP provided with the opening OP.

[0048] The display panel PNL further includes a first polarizer PL1 and a second polarizer PL2. The first polarizer PL1 is attached to the lower surface of the insulating substrate 10. The second polarizer PL2 is attached to the upper surface of the insulating substrate 20. The polarization axes (or absorption axes) of the polarizers PL1 and PL2 are orthogonal to each other. The display panel PNL may further include an optical functional layer other than the first polarizer PL1 and the second polarizer PL2.

[0049] Figure 4 2 is another schematic cross-sectional view of the display panel PNL. The switching element SW includes a semiconductor layer SC. Figure 4 The shown cross section corresponds to a cross section along the semiconductor layer SC.

[0050] The semiconductor layer SC is disposed on the insulating layer 11 and is covered by the insulating layer 12. The scanning line G is disposed on the insulating layer 12 and is covered by the insulating layer 13. Figure 4 In the cross section of , the scanning line G and the semiconductor layer SC are opposed to each other at two locations. That is, the switching element SW is a double-gate type. However, the switching element SW may also be a single-gate type.

[0051] The signal line S contacts a portion of the semiconductor layer SC through a contact hole CH1 provided in the insulating layers 12 and 13. The pixel electrode PE contacts another portion of the semiconductor layer SC through a contact hole CH2 provided in the insulating layers 12, 13, 14, and 15. A conductive layer for relaying may be provided between the pixel electrode PE and the semiconductor layer SC. The conductive layer may be formed of the same material as the signal line S and in the same layer as the signal line S, for example.

[0052] exist Figure 4 In the cross section of FIG. 1 , the semiconductor layer SC, the signal line S, the scanning line G, and the contact holes CH1 and CH2 face the light shielding layer 21 in the third direction Z. However, for example, a portion of the semiconductor layer SC may not face the light shielding layer 21 .

[0053] Here, the high-speed response mode will be described. Figure 5 and Figure 6 1 is a top view of a model M1 for explaining the operating principle of the high-speed response mode. The model M1 includes a lower electrode E1, an upper electrode E2 overlapping the lower electrode E1, and a plurality of liquid crystal molecules LM. The liquid crystal molecules LM in the model M1 have positive dielectric anisotropy.

[0054] The upper electrode E2 has a trunk TPm and a plurality of branch portions BPm extending from the trunk TPm. The branch portion BPm has: corners C1 and C2 at the tip side; corners C3 and C4 at the root side; a side 101 between the corners C1 and C3; and a side 102 between the corners C2 and C4.

[0055] exist Figure 5 In the example of , no electric field is formed between the lower electrode E1 and the upper electrode E2. At this time, the liquid crystal molecules LM are oriented by the action of the alignment film so that their long axes are aligned with the initial alignment direction AD. Figure 5 In the example, the initial orientation direction AD is consistent with the extension direction of the branch portion BPm.

[0056] exist Figure 6 In the example of , an electric field is formed between the lower electrode E1 and the upper electrode E2. The EL indicated by the dot-dash line in the figure is an example of the equipotential line of the electric field generated around the upper electrode E2. A rotational force acts on the liquid crystal molecule LM so that the long axis is parallel to the direction of the electric field (orthogonal to the equipotential line EL).

[0057] The liquid crystal molecules LM rotate in the first rotation direction R1 near the corners C1 and C3. Also, the liquid crystal molecules LM rotate in the second rotation direction R2 near the corners C2 and C4. The first rotation direction R1 and the second rotation direction R2 are different rotation directions (opposite rotation directions).

[0058] Corners C1 to C4 have an alignment control function (in other words, a function of stabilizing the alignment) of controlling the rotation direction of liquid crystal molecules LM near side edges 101 and 102. That is, liquid crystal molecules LM near side edge 101 are affected by the rotation of liquid crystal molecules LM near corners C1 and C3, and rotate in a first rotation direction R1. In addition, liquid crystal molecules LM near side edge 102 are affected by the rotation of liquid crystal molecules LM near corners C2 and C4, and rotate in a second rotation direction R2. When an image is displayed, the vicinity of side edges 101 and 102 becomes a high transmittance region (bright region).

[0059] On the other hand, near the center CL1 of the branch portion BPm and near the center CL2 in the region between the two branch portions BPm, the liquid crystal molecules LM rotating in the first rotation direction R1 counteract the liquid crystal molecules LM rotating in the second rotation direction R2. Therefore, at the centers CL1 and CL2, the liquid crystal molecules LM maintain their initial orientation state and hardly rotate. When an image is displayed, the vicinity of the centers CL1 and CL2 becomes a low transmittance region (dark region).

[0060] Figure 7 and Figure 8 1 is a top view of a model M2 for explaining the operating principle of the high-speed response mode. The model M2 is the same as the model M1, and includes a lower electrode E1, an upper electrode E2, and a plurality of liquid crystal molecules LM. However, the liquid crystal molecules LM in the model M2 have negative (negative type) dielectric anisotropy.

[0061] In the model M2, the initial orientation direction AD is orthogonal to the extension direction of the branch portion BPm. Figure 7 As shown, the liquid crystal molecules LM are aligned.

[0062] exist Figure 8 In the example of , an electric field is formed between the lower electrode E1 and the upper electrode E2. A rotational force acts on the liquid crystal molecules LM so that the long axis is perpendicular to the electric field direction (parallel to the equipotential lines EL).

[0063] In the model M2 as well, the liquid crystal molecules LM near the side 101 rotate in the first rotation direction R1, and the liquid crystal molecules LM near the side 102 rotate in the second rotation direction R2. In the centers CL1 and CL2, the liquid crystal molecules LM are maintained in the initial alignment state and hardly rotate.

[0064] In either model M1 or M2, regions where the liquid crystal molecules LM rotate in a predetermined direction and regions where the liquid crystal molecules LM do not rotate when an electric field is applied are alternately formed in the vertical direction of the figure. This can improve the response speed of the display device.

[0065] Fig. 9 1 is a schematic top view of the first common electrode CE1, the second common electrode CE2 and the pixel electrode PE of this embodiment. Here, four sub-pixels SP (SPa, SPb, SPc, SPd) are focused on. In the display area DA, the structure composed of these sub-pixels SPa, SPb, SPc, SPd is repeatedly arranged in the first direction X and the second direction Y.

[0066] The sub-pixels SPa, SPb, SPc, and SPd are any of the above-mentioned sub-pixels SPR, SPG, and SPB. The sub-pixels SPa and SPb are arranged in the first direction X, the sub-pixels SPc and SPd are arranged in the first direction X, the sub-pixels SPa and SPc are arranged in the second direction Y, and the sub-pixels SPb and SPd are arranged in the second direction Y.

[0067] The second common electrode CE2 includes a plurality of trunk portions TP extending in the first direction X and a plurality of branch portions BP extending from each of the trunk portions TP. Fig. 9 , three trunks TP (first to third trunks TPa, TPb, TPc) and four branches BP (first to fourth branches BPa, BPb, BPc, BPd) arranged in the second direction Y are shown. The branches BPa and BPb extend from the trunk TPb toward the trunk TPa. The branches BPc and BPd extend from the trunk TPc toward the trunk TPb. The extension direction of the branches BPa, BPb, BPc, BPd is parallel to the second direction Y.

[0068] The sub-pixels SPa, SPb, SPc, and SPd are respectively designed with openings OP (first to fourth openings OPa, OPb, OPc, and OPd). The openings OPa and OPb are located between the main body portions TPa and TPb. The openings OPc and OPd are located between the main body portions TPb and TPc. That is, Fig. 9 In the example, the main bodies TPa, TPb, and TPc overlap with the above-mentioned light-shielding layer 21.

[0069] The sub-pixels SPa, SPb, SPc, and SPd are respectively provided with pixel electrodes PE (first to fourth pixel electrodes PEa, PEb, PEc, and PEd) and semiconductor layers SC (first to fourth semiconductor layers SCa, SCb, SCc, and SCd). Most of the pixel electrodes PEa and PEb are located between the main body portions TPa and TPb. Most of the pixel electrodes PEc and PEd are located between the main body portions TPb and TPc.

[0070] The branch portion BPa has a pair of side edges 31 and 32 arranged in the first direction X, a root portion 33, and a front end portion 34. The side edge 31 is inclined so as to form an acute angle θ1 clockwise with respect to the second direction Y. The side edge 32 is inclined so as to form an acute angle θ1 counterclockwise with respect to the second direction Y. The root portion 33 corresponds to the connection portion between the branch portion BPa and the main body TPb. The front end portion 34 is separated from the main body TPa.

[0071] The pixel electrode PEa is a trapezoidal shape having a pair of side sides 41 and 42 arranged in the first direction X, a short side 43 (upper base), and a long side 44 (lower base) parallel to the short side 43. The side side 41 is inclined so as to form an acute angle θ2 with respect to the second direction Y. The side side 42 is inclined so as to form an acute angle θ2 clockwise with respect to the second direction Y. The short side 43 and the long side 44 are parallel to the first direction X.

[0072] Since the side edges 41 and 42 are inclined as described above, the width Wpe of the pixel electrode PEa between the side edges 41 and 42 decreases as it approaches the trunk TPb (or the root 33 or the short side 43). Most of the branch portion BPa and the pixel electrode PEa overlap with the opening OPa. The branch portion BPa overlaps with the pixel electrode PEa between the side edges 41 and 42.

[0073] The acute angles θ1 and θ2 are, for example, less than 10 degrees. As another example, the acute angles θ1 and θ2 are less than 5 degrees. Fig. 9 In the example of FIG. 1 , the acute angle θ1 is smaller than the acute angle θ2. In this case, the branch portion BPa having a smaller width than the pixel electrode PEa can be formed as long as possible. However, the acute angle θ1 may be greater than the acute angle θ2.

[0074] exist Fig. 9 In the example of FIG. 4 , the short side 43 overlaps with the main body TPb, and the long side 44 overlaps with the main body TPa. However, the short side 43 and the main body TPb may not overlap. In addition, the long side 44 and the main body TPa may not overlap.

[0075] The branch portions BPb, BPc, and BPd have the same shape as the branch portion BPa. In addition, the pixel electrodes PEb, PEc, and PEd have the same shape as the pixel electrode PEa.

[0076] The first common electrode CE1 has a shape that completely overlaps with the sub-pixels SPa, SPb, SPc, and SPd. Fig. 9 In the figure, the first common electrode CE1 exists in a region where the second common electrode CE2 and each pixel electrode PE do not exist.

[0077] Fig.10 is a schematic top view showing a more detailed structure applicable to the sub-pixel SP. Fig. 9 The sub-pixel SPa shown. The opening OPa of the sub-pixel SPa is surrounded by two scanning lines G (first and second scanning lines Ga, Gb) and two signal lines S (first and second signal lines Sa, Sb). The scanning lines Ga, Gb and the signal lines Sa, Sb overlap with the light shielding layer 21 as a whole. In addition, the scanning line Ga overlaps with the main body TPa, and the scanning line Gb overlaps with the main body TPb.

[0078] exist Fig.10 In the example, the short side 43 of the pixel electrode PEa overlaps with the scanning line Gb, and the long side 44 of the pixel electrode PEa overlaps with the scanning line Ga. As another example, the short side 43 may be separated from the scanning line Gb in the second direction Y, and the long side 44 may be separated from the scanning line Ga in the second direction Y. Fig.10 In the example of FIG. 1 , the pixel electrode PEa does not overlap with the signal lines Sa and Sb. As another example, a portion of the pixel electrode PEa may overlap with at least one of the signal lines Sa and Sb.

[0079] exist Fig.10 In the example of FIG. 1 , the width W43 of the short side 43 of the pixel electrode PEa is greater than the width W33 of the root 33 of the branch portion BPa. Furthermore, in the first direction X, the side sides 41 and 42 of the pixel electrode PEa are separated from the root 33 .

[0080] The semiconductor layer SCa of the sub-pixel SPa and the signal line Sa are connected through the contact hole CH1 (see Figure 4 ) is connected. In addition, the semiconductor layer SCa and the pixel electrode PEa are connected via a contact hole CH2 (see Figure 4 The semiconductor layer SCa intersects the scanning line Ga twice between the contact holes CH1 and CH2.

[0081] The contact hole CH1 is located between the scanning lines Ga and Gb and close to the scanning line Ga. The contact hole CH2 is located between the opening OPa and the long side 44. It can also be said that the contact hole CH2 is located between the opening OPa and the scanning line Ga, between the opening OPa and the main body TPa, or at the corner formed by the side 41 and the long side 44.

[0082] For other sub-pixels SP including sub-pixels SPb, SPc, and SPd, the same Fig.10 The sub-pixel SPa shown has the same structure.

[0083] If the structure of this embodiment is as described above, then Fig. 9 As shown in the example, a first common voltage region Ac1, a second common voltage region Ac2, and a pixel voltage region Ap are formed between the trunk portions TPb and TPc. The first common voltage region Ac1 and the second common voltage region Ac2 are regions to which a common voltage is applied. The pixel voltage region Ap is a region to which a pixel voltage is applied.

[0084] The first common voltage region Ac1 is a region where the first common electrode CE1 is formed but the second common electrode CE2 and the pixel electrode PE are not formed, and is located between two pixel electrodes PE adjacent to each other in the first direction X. The second common voltage region Ac2 is a region where the branch portion BP is formed, and is located between a pair of first common voltage regions Ac1 in the first direction X. The pixel voltage region Ap is a region where the pixel electrode PE is formed but the second common electrode CE2 is not formed, and is located between a pair of first common voltage regions Ac1 and second common voltage regions Ac2 in the first direction X, respectively.

[0085] exist Fig. 9 In the example, the initial alignment direction AD of the liquid crystal molecules LM coincides with the second direction Y. That is, the first alignment film 17 and the second alignment film 24 align the liquid crystal molecules LM in the second direction Y. The liquid crystal molecules LM have positive dielectric anisotropy.

[0086] When an electric field is formed between the common electrodes CE1 and CE2 and the pixel electrode PE, the liquid crystal molecules LM rotate in the first rotation direction R1 near the side 31 of the branch portion BP or near the side 42 of the pixel electrode PE. In addition, the liquid crystal molecules LM rotate in the second rotation direction R2 near the side 32 of the branch portion BP or near the side 41 of the pixel electrode PE.

[0087] On the other hand, the rotation of the liquid crystal molecules LM is suppressed at the center CLc1 of the first common voltage region Ac1 in the first direction X, the center CLc2 of the second common voltage region Ac2 in the first direction X, and the center CLp of the pixel voltage region Ap in the first direction X. Thus, the same high-speed response mode as the above-mentioned model M1 is realized.

[0088] Assuming that the first common voltage region Ac1 and the second common voltage region Ac2 are formed by one conductive layer, the common voltage regions Ac1 and Ac2 need to be patterned at a narrow pitch in the first direction X. For example, when implementing a high-definition display device DSP of more than 2000 ppi, it may be difficult to form the common voltage regions Ac1 and Ac2 by one conductive layer due to the resolution limit of patterning.

[0089] In contrast, in the present embodiment, the first common voltage region Ac1 and the second common voltage region Ac2 are formed by different conductive layers overlapping in the third direction Z. Therefore, these common voltage regions Ac1 and Ac2 can be arranged at a narrow pitch. In addition, a pair of pixel voltage regions Ap in each sub-pixel SP is formed by overlapping the branch portion BP with the pixel electrode PE. Therefore, it is not necessary to finely pattern the pixel electrode PE. Thus, a high-precision display device DSP can be manufactured.

[0090] Furthermore, in the present embodiment, the pixel electrode PE has a shape in which the width Wpe decreases as it approaches the trunk TP to which the branch BP overlapping the pixel electrode PE is connected. Thus, the side edges 41 and 42 of the pixel electrode PE are inclined in a manner to form an acute angle θ2 with respect to the second direction Y (initial alignment direction AD). In such a structure, it is easier to determine the rotation direction of the liquid crystal molecules LM near the side edges 41 and 42 than in a case where the side edges 41 and 42 are parallel to the second direction Y. As a result, the alignment stability of the liquid crystal molecules LM is improved, and the display quality of the display device DSP is improved.

[0091] In the present embodiment, the side edges 31 and 32 of the branch portion BP are inclined to form an acute angle θ1 with respect to the second direction Y (initial alignment direction AD). Thus, as in the case of the side edges 41 and 42 , the alignment stability of the liquid crystal molecules LM is improved.

[0092] Fig.11 1 is a schematic top view of sub-pixels SPa, SPb, SPc, and SPd of another example of this embodiment. In this example, the initial alignment direction AD is parallel to the first direction X (the extension direction of the main body TP), and the liquid crystal molecules LM have negative dielectric constant anisotropy. That is, the first alignment film 17 and the second alignment film 24 align the liquid crystal molecules LM in the first direction X. Other structures are similar to Fig. 9 same.

[0093] and Fig. 9 As in the example of , when an electric field is formed between the common electrodes CE1 and CE2 and the pixel electrode PE, the liquid crystal molecules LM rotate in the first rotation direction R1 near the side edges 31 and 42, and rotate in the second rotation direction R2 near the side edges 32 and 41. On the other hand, the rotation of the liquid crystal molecules LM is suppressed at the center CLc1, CLc2, and CLp. Thus, the same high-speed response mode as the above-mentioned model M2 is achieved.

[0094] exist Fig.11 In the example of FIG. 1 , the side edges 31, 32, 41, 42 are inclined to form an acute angle with respect to the second direction Y (a direction orthogonal to the initial alignment direction AD), so that the rotation direction of the liquid crystal molecules LM near the side edges 31, 32, 41, 42 is easily determined. As a result, the alignment stability of the liquid crystal molecules LM is improved, and the display quality of the display device DSP is improved.

[0095] In addition to the above, various preferable effects can be obtained according to the present embodiment.

[0096] [Second Embodiment]

[0097] The second embodiment will be described. The structure not particularly mentioned is the same as that of the first embodiment.

[0098] Fig.12 1 is a schematic plan view of sub-pixels SPa, SPb, SPc, and SPd according to Embodiment 2. In the display area DA, the structure composed of these sub-pixels SPa, SPb, SPc, and SPd is repeatedly arranged in the first direction X and the second direction Y.

[0099] exist Fig.12 In the example, the structures of sub-pixels SPa and SPc are similar to Fig. 9 The example is the same as that of FIG. 1 , but the structures of the sub-pixels SPb and SPd are the same as those of FIG. Fig. 9 That is, the sub-pixels SPb and SPd have shapes that are line-symmetrical with the sub-pixels SPa and SPc about an axis parallel to the first direction X.

[0100] Specifically, the branch BPb extends from the trunk TPa toward the trunk TPb, and the branch BPd extends from the trunk TPb toward the trunk TPc. In addition, the pixel electrode PEb has a shape whose width decreases as it approaches the trunk TPa, and the pixel electrode PEd has a shape whose width decreases as it approaches the trunk TPb.

[0101] exist Fig.12 In the example of FIG. 1 , the opening OPa of the sub-pixel SPa and the opening OPb of the sub-pixel SPb are offset in the second direction Y. That is, the openings OPa and OPb have the same size, but the distance between the opening OPb and the main body TPa is smaller than the distance between the opening OPa and the main body TPa. Moreover, the distance between the opening OPb and the main body TPb is larger than the distance between the opening OPa and the main body TPb. The relationship between the opening OPc of the sub-pixel SPc and the opening OPd of the sub-pixel SPd is the same as the relationship between the openings OPa and OPb.

[0102] The semiconductor layer SCa of the sub-pixel SPa is arranged in the same manner as Fig.10 The semiconductor layer SCa is the same as shown in FIG. That is, a portion of the semiconductor layer SCa overlaps with the main body TPa. On the other hand, a portion of the semiconductor layer SCb of the sub-pixel SPb overlaps with the main body TPb. The contact hole CH2 connecting the semiconductor layer SCb and the pixel electrode PEb is located between the opening OPb and the main body TPb. The semiconductor layer SCc of the sub-pixel SPc and the semiconductor layer SCd of the sub-pixel SPd are configured in the same manner as the semiconductor layers SCa and SCb, respectively. That is, a portion of the semiconductor layer SCc overlaps with the main body TPb, and a portion of the semiconductor layer SCd overlaps with the main body TPc.

[0103] and Fig.10 Similar to the example of FIG. 1 , a first common voltage region Ac1, a second common voltage region Ac2, and a pixel voltage region Ap are formed between adjacent trunk portions TP. Fig.10In the example of , the width of the first common voltage region Ac1 is not constant, but decreases as it approaches the long side 44 of the adjacent pixel electrode PE. Fig.12 In the example, the width of the first common voltage region Ac1 in the first direction X (the interval between adjacent pixel electrodes PE in the first direction X) is constant. Therefore, even when the pixel electrodes PE are arranged at a narrow interval in the first direction X, adjacent pixel electrodes PE are unlikely to be short-circuited.

[0104] exist Fig.12 , the initial alignment direction AD is consistent with the second direction Y, and the liquid crystal molecules LM with positive dielectric constant anisotropy rotate due to the electric field. In this embodiment, since the sides of the adjacent pixel electrodes PE in the first direction X are parallel to each other, as in Fig.12 The liquid crystal molecules LM in the first common voltage region Ac1 have the same rotation direction as the liquid crystal molecules LM shown overlapping the side 42 of the pixel electrode PEc and the side 41 of the pixel electrode PEd. As a result, it is difficult to form a portion where the liquid crystal molecules LM do not rotate in the first common voltage region Ac1. Therefore, from the perspective of achieving a stable high-speed response mode, the structure of the first embodiment has an advantage.

[0105] In addition, in the structure of this embodiment, it is also possible to Fig.11 The same as the example, the initial alignment direction AD is parallel to the first direction X, and the liquid crystal molecules LM have negative dielectric anisotropy.

[0106] [Third Embodiment]

[0107] The third embodiment will be described. The configuration not specifically mentioned is the same as that of the above-mentioned embodiments.

[0108] Fig.13 1 is a schematic plan view of sub-pixels SPa, SPb, SPc, and SPd according to Embodiment 3. In the display area DA, the structure composed of these sub-pixels SPa, SPb, SPc, and SPd is repeatedly arranged in the first direction X and the second direction Y.

[0109] exist Fig.13 In the example, the structures of sub-pixels SPa and SPb are similar to Fig. 9 The example is similar to that of Fig. 9 That is, both the branch portions BPc and BPd extend from the main body TPb toward the main body TPc, and both the pixel electrodes PEc and PEd have a shape in which the width decreases as they approach the main body TPb.

[0110] exist Fig.13, single-gate semiconductor layers SCa, SCb, SCc, and SCd are exemplified. The semiconductor layers SCa, SCb, SCc, and SCd may be dual-gate semiconductor layers like those in the above-mentioned embodiments.

[0111] exist Fig.13 In the example, a portion of the semiconductor layer SCa overlaps with the main body TPa. The contact hole CH2 connecting the semiconductor layer SCa and the pixel electrode PEa is located between the opening OPa and the main body TPa near the corner formed by the side 41 and the long side 44. The configuration of the semiconductor layer SCb is the same as that of the semiconductor layer SCa.

[0112] In addition, Fig.13 In the example, a portion of the semiconductor layer SCc overlaps the main body TPc. The contact hole CH2 connecting the semiconductor layer SCc and the pixel electrode PEc is located between the opening OPc and the main body TPc near the corner formed by the side 42 and the long side 44. The configuration of the semiconductor layer SCd is the same as that of the semiconductor layer SCc.

[0113] In the structure of this embodiment, Fig. 9 The same as the example, a first common voltage region Ac1, a second common voltage region Ac2 and a pixel voltage region Ap are formed between two adjacent trunk portions TP. Fig.13 , the initial alignment direction AD is consistent with the second direction Y, and the liquid crystal molecules LM with positive dielectric anisotropy rotate due to the electric field. As another example, the initial alignment direction AD may be parallel to the first direction X, and the liquid crystal molecules LM may have negative dielectric anisotropy.

[0114] [Fourth Embodiment]

[0115] The fourth embodiment is described below. The structure not specifically mentioned is the same as that of the above-mentioned embodiments.

[0116] Fig.14 1 is a schematic plan view of sub-pixels SPa, SPb, SPc, and SPd according to Embodiment 4. In the display area DA, the structure composed of these sub-pixels SPa, SPb, SPc, and SPd is repeatedly arranged in the first direction X and the second direction Y.

[0117] exist Fig.14 In the example, the structures of sub-pixels SPa and SPd are similar to Fig. 9 In addition, the structures of the sub-pixels SPb and SPc are the same as Fig.12That is, the branch portion BPa extends from the main body TPb toward the main body TPa, the branch portion BPb extends from the main body TPa toward the main body TPb, the branch portion BPc extends from the main body TPb toward the main body TPc, and the branch portion BPd extends from the main body TPc toward the main body TPb.

[0118] In addition, the pixel electrode PEa has a shape whose width becomes smaller as it approaches the main body TPb, the pixel electrode PEb has a shape whose width becomes smaller as it approaches the main body TPa, the pixel electrode PEc has a shape whose width becomes smaller as it approaches the main body TPb, and the pixel electrode PEd has a shape whose width becomes smaller as it approaches the main body TPc.

[0119] In the structure of this embodiment, Fig. 9 Similar to the example of FIG. 1 , a first common voltage region Ac1, a second common voltage region Ac2, and a pixel voltage region Ap are formed between two adjacent trunk portions TP. Fig.12 The same as the example, the width of the first common voltage region Ac1 in the first direction X (the interval between the adjacent pixel electrodes PE in the first direction X) is constant.

[0120] exist Fig.14 , the initial alignment direction AD is consistent with the second direction Y, and the liquid crystal molecules LM with positive dielectric anisotropy rotate due to the electric field. As another example, the initial alignment direction AD may be parallel to the first direction X, and the liquid crystal molecules LM may have negative dielectric anisotropy.

[0121] Based on the liquid crystal display device described above as an embodiment of the present invention, all display devices that can be implemented by those skilled in the art by appropriately changing the design are also within the scope of the present invention as long as they include the gist of the present invention.

[0122] Within the scope of the present invention, those skilled in the art can think of various variations, which also fall within the scope of the present invention. For example, for the above-mentioned embodiments, those skilled in the art can appropriately add, delete or design the embodiments after structural elements are added, deleted or the embodiments after conditions are changed, as long as they have the gist of the present invention, they are also included in the scope of the present invention.

[0123] In addition, regarding other effects brought about by the means described in the above embodiments, it is naturally understood that the contents that are clear from the description of this specification or the contents that can be appropriately conceived by those skilled in the art are brought about by the present invention.

Claims

1. A liquid crystal display device comprising: a first substrate; a second substrate, opposite to the first substrate; as well as a liquid crystal layer, located between the first substrate and the second substrate, The first substrate comprises: A first common electrode to which a common voltage is applied; a second common electrode, located between the first common electrode and the liquid crystal layer in the thickness direction of the first substrate and applied with the common voltage; A first pixel electrode, located between the first common electrode and the second common electrode in the thickness direction and having a pair of first side edges arranged in a first direction; as well as a second pixel electrode located between the first common electrode and the second common electrode in the thickness direction; The second common electrode has: The first main body portion, the second main body portion and the third main body portion respectively extend in the first direction and are arranged in a second direction intersecting the first direction; a first branch portion extending from the second main trunk portion toward the first main trunk portion; as well as A second branch portion extends from the second main trunk portion toward the third main trunk portion, The first pixel electrode is located between the first main body portion and the second main body portion. The first branch portion overlaps the first pixel electrode between the pair of first sides, and the width of the first pixel electrode between the pair of first sides decreases as it approaches the second main body portion. The second pixel electrode is located between the second trunk portion and the third trunk portion in the second direction. The second pixel electrode has a pair of second sides arranged in the first direction, The second branch portion overlaps the second pixel electrode between the pair of second sides, and a width of the second pixel electrode between the pair of second sides decreases as it approaches the second trunk portion.

2. The liquid crystal display device according to claim 1, The first substrate has, when viewed from above: a pair of first common voltage regions, in which the first common electrode is formed, but the second common electrode and the first pixel electrode are not formed; A second common voltage region, located between the pair of first common voltage regions in the first direction, and having the first branch portion formed therein; as well as The pixel voltage region is located between the pair of first common voltage regions and the second common voltage region in the first direction, and has the first pixel electrode formed therein.

3. The liquid crystal display device according to claim 1, The pair of first sides respectively form an acute angle with respect to the second direction.

4. The liquid crystal display device according to claim 3, The first pixel electrode has a trapezoidal shape having the pair of first side edges and short sides and long sides parallel to the first direction.

5. The liquid crystal display device according to claim 4, The width of the short side is greater than the width of the root of the first branch portion.

6. The liquid crystal display device according to claim 1, The front end portion of the first branch portion is separated from the first trunk portion.

7. The liquid crystal display device according to claim 1, The first substrate further includes a third pixel electrode, the third pixel electrode being located between the first common electrode and the second common electrode in the thickness direction and between the first trunk portion and the second trunk portion in the second direction. The second common electrode further comprises a third branch portion extending from the first main body portion toward the second main body portion, The third pixel electrode has a pair of third sides arranged in the first direction, The third branch portion overlaps the third pixel electrode between the pair of third sides. A width of the third pixel electrode between the pair of third sides decreases as it approaches the first trunk portion.

8. The liquid crystal display device according to claim 7, The pair of third sides respectively form acute angles with respect to the second direction.

9. The liquid crystal display device according to claim 8, The third pixel electrode has a trapezoidal shape having the pair of third side edges and short sides and long sides parallel to the first direction.

10. The liquid crystal display device according to claim 9, The width of the short side is greater than the width of the root of the third branch portion.

11. The liquid crystal display device according to claim 7, The front end portion of the third branch portion is separated from the second trunk portion.

12. The liquid crystal display device according to claim 1, The pair of second side edges respectively form acute angles with respect to the second direction.

13. The liquid crystal display device according to claim 12, The second pixel electrode has a trapezoidal shape having the pair of second side edges and short sides and long sides parallel to the first direction.

14. The liquid crystal display device according to claim 13, The width of the short side is greater than the width of the root of the second branch portion.

15. The liquid crystal display device according to claim 1, The front end portion of the second branch portion is separated from the third main portion.

16. The liquid crystal display device according to claim 1, The first substrate has a first alignment film, The second substrate has a second alignment film, The liquid crystal molecules contained in the liquid crystal layer have positive dielectric anisotropy. The first alignment film and the second alignment film align the liquid crystal molecules in the second direction.

17. The liquid crystal display device according to claim 1, The first substrate has a first alignment film, The second substrate has a second alignment film, The liquid crystal molecules contained in the liquid crystal layer have negative dielectric anisotropy. The first alignment film and the second alignment film align the liquid crystal molecules in the first direction.

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