Liquid crystal display

Abstract

To provide a liquid crystal display capable of sufficiently preventing an afterimage from occurring and useful even as an in-cell type touch panel capable of displaying a reflection mode.SOLUTION: A liquid crystal display includes a first substrate, a second substrate facing the first substrate, and a liquid crystal layer provided between the first and second substrates, and has a plurality of pixels arranged in a matrix manner. The first substrate includes a reflective layer for reflecting light, first and second electrode capable of generating a transverse electric field in the liquid crystal layer and a first horizontal alignment film contacting the liquid crystal layer; at least one of the first and second electrodes includes a plurality of belt-like parts and a slit positioned between two belt-like parts adjacent to each other in the plurality of belt-like parts; in each pixel, the plurality of belt-like parts are approximately parallel to each other and consisting of a linear shape extending in the same direction without including a bent part; the second substrate includes a second horizontal alignment film contacting the liquid crystal layer; and the liquid crystal layer has twist alignment when no voltage is applied.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The following disclosure relates to liquid crystal displays. [Background technology]

[0002] Liquid crystal display devices are display devices that use liquid crystal material for display, and are generally broadly classified into transmissive liquid crystal display devices and reflective liquid crystal display devices according to the display method. Transmissive liquid crystal display devices are devices that perform display in a transmissive mode using transmitted light from a backlight behind the screen, while reflective liquid crystal display devices are devices that perform display in a reflective mode using external light (also called ambient light) instead of backlight light. As a display device that combines these characteristics, a semi-transmissive liquid crystal display device has been proposed in which each pixel has an area that performs display in a transmissive mode and an area that performs display in a reflective mode (see, for example, Patent Document 1).

[0003] Liquid crystal display devices can also be broadly classified according to the driving method of the liquid crystal. For example, there are known vertical electric field type liquid crystal display devices that drive a liquid crystal layer with an electric field in a direction substantially perpendicular to the substrate surface to perform display, and horizontal electric field type liquid crystal display devices that drive a liquid crystal layer with an electric field in a direction substantially parallel to the substrate surface to perform display. Examples of the vertical electric field type include the twisted nematic (TN) mode and the multi-domain vertical alignment (MVA) mode, and examples of the horizontal electric field type include the in-plane switching (IPS) mode and the fringe field switching (FFS) mode. For example, Patent Document 2 discloses a liquid crystal display that is suitable as a horizontal electric field type liquid crystal display device. This liquid crystal display is capable of suppressing defects caused by process variations and improving display performance, and is particularly useful as a transmissive liquid crystal display device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5767195 [Patent Document 2] Patent No. 5756860 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, liquid crystal display devices used in smartphones, tablets, and the like are usually provided with a touch sensor function. There are various types of touch sensors known, such as resistive film type, electrostatic capacitance type, and optical type. Liquid crystal display devices equipped with a touch sensor (also called touch panel) include a type in which the touch sensor is attached externally (external type) and a type in which the touch sensor is built-in (built-in type). The built-in type touch panel is advantageous in terms of narrowing the frame, reducing the thickness, and reducing the weight, etc., compared to the external type touch panel, and also has the advantage of increasing the light transmittance.

[0006] Built-in touch panels are classified into on-cell type and in-cell type. The cell means a display panel (also called a liquid crystal panel) that includes an active matrix substrate, typically a thin film transistor (TFT) substrate, an opposing substrate arranged to face the active matrix substrate, and a liquid crystal layer arranged between the substrates. In general, in the in-cell type, a layer that performs the touch sensor function is arranged in the display panel, while in the on-cell type, a layer that performs the touch sensor function is arranged between the display panel and a polarizing plate arranged on the observation surface side of the display panel. Among these, the in-cell type can theoretically realize the thinnest and lightest touch panel. In addition, liquid crystal display devices capable of displaying in a reflective mode are suitable for outdoor use, so that an in-cell type touch panel capable of displaying in a reflective mode is required, but has not yet been realized.

[0007] The reason why this has not been realized is believed to be that in current reflective liquid crystal display devices, one of a pair of electrodes for applying a voltage to the liquid crystal layer (also called a counter electrode or a common electrode) is arranged on the counter substrate side. Therefore, the present inventors believed that an in-cell type touch panel capable of displaying in the reflective mode could be realized if a lateral electric field method such as the FFS mode is used, since both of the pair of electrodes are provided only on the active matrix substrate side, and so they have been actively studying lateral electric field liquid crystal display devices.

[0008] Specifically, a TFT substrate for a mobile device was used, and a pixel electrode and a common electrode for applying a voltage to the liquid crystal layer were arranged on the TFT substrate side, and the common electrode was made into a slit electrode having a slit-shaped opening. Furthermore, a negative type liquid crystal material was used to fabricate an FFS mode device capable of displaying in a reflective mode (see Verification Example 1 described later). In such a device, since alignment disturbance occurs due to the influence of the electric field at the pixel end, the strip-shaped portion constituting the slit electrode is usually made into a shape like a straight line bent halfway. When this device was set to a white display state, black characters were written on the device in that state, and then the written characters were erased (i.e., the device was returned to the white display state), an afterimage of the characters was visually recognized as burn-in (see Figure 20C). Such an afterimage can also occur during normal screen operation or video playback. Therefore, such a device has the problem of afterimage generation.

[0009] The present invention has been made in consideration of the above-mentioned current situation, and aims to provide a liquid crystal display device that can sufficiently suppress the occurrence of afterimages and is also useful as an in-cell type touch panel capable of displaying in a reflective mode. [Means for solving the problem]

[0010] (1) One embodiment of the present invention is a liquid crystal display device comprising a first substrate, a second substrate opposed to the first substrate, and a liquid crystal layer provided between the first substrate and the second substrate, the liquid crystal display device having a plurality of pixels arranged in a matrix, the first substrate having a reflective layer that reflects light, a first electrode and a second electrode capable of generating a transverse electric field in the liquid crystal layer, and a first horizontal alignment film in contact with the liquid crystal layer, at least one of the first electrode and the second electrode having a plurality of strip portions and a slit located between two adjacent strip portions among the plurality of strip portions, in each pixel, the plurality of strip portions have linear shapes that are approximately parallel to each other and extend in the same direction, and do not include any bent portions, the second substrate having a second horizontal alignment film in contact with the liquid crystal layer, and the liquid crystal layer has a twisted alignment when no voltage is applied.

[0011] (2) Moreover, in one embodiment of the present invention, in addition to the configuration (1) above, the plurality of strip-shaped portions do not include any notches.

[0012] (3) Furthermore, in one embodiment of the present invention, in addition to the configuration of (1) or (2) above, the direction in which the multiple strip portions extend is the same at least in adjacent pixels or in the display region.

[0013] (4) Moreover, an embodiment of the present invention is a liquid crystal display device having the configuration of (1), (2), or (3) above, wherein the liquid crystal layer contains a positive type liquid crystal material.

[0014] (5) Moreover, an embodiment of the present invention is a liquid crystal display device having the configuration of (1), (2), or (3) above, wherein the liquid crystal layer contains a negative type liquid crystal material.

[0015] (6) Furthermore, one embodiment of the present invention is a liquid crystal display device having the configuration of (1), (2), (3), (4) or (5) above, wherein the twist angle of the liquid crystal layer when no voltage is applied is 58.3° or more and 89.9° or less.

[0016] (7) Moreover, an embodiment of the present invention is a liquid crystal display device having the configuration of (1), (2), (3), (4), (5) or (6) above, and further having a single domain alignment.

[0017] (8) Furthermore, one embodiment of the present invention is a liquid crystal display device, in which, in addition to the configuration of (1), (2), (3), (4), (5), (6) or (7), the alignment direction of the liquid crystal molecules on the first substrate side when no voltage is applied is between -30° and 30° with respect to the direction in which the multiple strip-shaped portions extend (0°).

[0018] (9) Furthermore, in one embodiment of the present invention, in addition to the configuration of (1), (2), (3), (4), (5), (6), (7) or (8), the ratio L / S of the width L of each strip portion in a planar view to the width S of each slit in a planar view is 0.4 to 0.7 / 1.

[0019] (10) Furthermore, in an embodiment of the present invention, in addition to the configuration of (1), (2), (3), (4), (5), (6), (7), (8), or (9), a liquid crystal display device further comprises a polarizing plate disposed on the outer side of the first substrate and / or the second substrate, and a retardation layer disposed between the substrate and the polarizing plate.

[0020] (11) Furthermore, one embodiment of the present invention is a liquid crystal display device having the configuration of (10) above, wherein the liquid crystal layer contains a positive liquid crystal material, the polarizing plate is an absorptive polarizing plate, and the light absorption axis of the polarizing plate is at an angle of 5° or more and 35° or less with respect to a direction perpendicular to the extension direction of the multiple strip-shaped portions (0°).

[0021] (12) Furthermore, in an embodiment of the present invention, in addition to the configuration of (10) or (11), the liquid crystal layer includes a positive liquid crystal material, the retardation layer includes a λ / 2 plate, and the in-plane slow axis of the λ / 2 plate is at an angle of 25° or more and 50° or less with respect to a direction perpendicular to the extension direction of the multiple strip-shaped portions as a reference (0°).

[0022] (13) Furthermore, an embodiment of the present invention is a liquid crystal display device, in addition to the configuration of (10), (11), or (12), wherein the liquid crystal layer includes a positive liquid crystal material, the retardation layer includes a λ / 4 plate, and an in-plane slow axis of the λ / 4 plate is at an angle of 45° or more and 70° or less with respect to a direction perpendicular to the extension direction of the plurality of strip-shaped portions as a reference (0°).

[0023] (14) Furthermore, in one embodiment of the present invention, in addition to the configuration of (10) above, the liquid crystal layer includes a negative liquid crystal material, the polarizing plate is an absorptive polarizing plate, and the absorption axis of the polarizing plate is at an angle of -85° or more and -55° or less, with a direction perpendicular to the extension direction of the multiple strip-shaped portions as a reference (0°).

[0024] (15) Furthermore, an embodiment of the present invention is a liquid crystal display device having the configuration of (10) or (14) above, wherein the liquid crystal layer includes a negative liquid crystal material, the retardation layer includes a λ / 2 plate, and an in-plane slow axis of the λ / 2 plate is at an angle of −65° or more and −40° or less with respect to a direction perpendicular to the extension direction of the plurality of strip-shaped portions as a reference (0°).

[0025] (16) Furthermore, an embodiment of the present invention is a liquid crystal display device having the configuration of (10), (14), or (15) above, wherein the liquid crystal layer includes a negative liquid crystal material, the retardation layer includes a λ / 4 plate, and an in-plane slow axis of the λ / 4 plate is at an angle of −40° or more and −15° or less with respect to a direction perpendicular to the extension direction of the plurality of strip-shaped portions as a reference (0°).

[0026] (17) Furthermore, an embodiment of the present invention is a liquid crystal display device that performs display in a normally black mode in addition to the configuration of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15), or (16).

[0027] (18) Furthermore, in an embodiment of the present invention, in addition to the configuration of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15), (16) or (17), one of the first electrode and the second electrode is a pixel electrode provided in each of the plurality of pixels, and the other is a common electrode including a plurality of segments each capable of functioning as a touch sensor electrode, and the first substrate has a plurality of touch wirings each connected to a corresponding one of the touch sensor electrodes.

[0028] (19) Furthermore, in one embodiment of the present invention, in addition to the configuration of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (17), or (18), a liquid crystal display device further includes a light source. Effect of the Invention

[0029] According to the present invention, it is possible to provide a liquid crystal display device that can sufficiently suppress the occurrence of an afterimage and is also useful as an in-cell type touch panel capable of displaying in a reflective mode. [Brief description of the drawings]

[0030] [Figure 1] 1 is a schematic cross-sectional view of a liquid crystal display device 1 according to an example of a first embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing in more detail an example of a liquid crystal display device 1 according to the first embodiment. [Diagram 3] FIG. 1 is a plan view illustrating an example of a liquid crystal display device 1 according to a first embodiment as a whole, as viewed from the observation surface side. [Figure 4A] 1 is a diagram for explaining the slit angle of positive type liquid crystal molecules. FIG. [Figure 4B] 13 is a diagram for explaining the slit angle of negative type liquid crystal molecules. FIG. [Diagram 5] 1 is a schematic plan view showing an example of a pixel structure (angle X is 0°). [Figure 6A] 1 is a schematic plan view showing an example of a pixel arrangement (angle X is 0°). [Figure 6B] 1 is a plan view showing an example of a pixel arrangement (angle X is −10°). FIG. [Figure 6C] 1 is a schematic plan view showing an example of a pixel arrangement (angle X is +10°). [Figure 6D] 1 is a schematic plan view showing an example of a pixel arrangement (angle X is −90°). [Figure 6E] 1 is a schematic plan view showing an example of a pixel arrangement (angle X is −100°). [Figure 6F] FIG. 2 is a plan view showing an example of a pixel arrangement (angle X is −80°). [Figure 7] 2 is a plan view illustrating a schematic arrangement of touch sensor electrodes TX and touch wirings TL included in the liquid crystal display device 1. FIG. [Figure 8] 1 is a schematic cross-sectional view showing a liquid crystal display device 1 according to Modification 1 of Embodiment 1 in more detail. [Figure 9] 1 is a schematic cross-sectional view of a liquid crystal display device 1 according to an example of a second embodiment. [Figure 10] FIG. 11 is a cross-sectional view showing in more detail a liquid crystal display device 1 as an example of the second embodiment. [Figure 11] In a liquid crystal display device 1 having, in order from the rear side, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a λ / 4 plate 41, a λ / 2 plate 42, and a polarizing plate 50, this is a plan view conceptually showing the relationship between the long axis direction of liquid crystal molecules 21 in the liquid crystal layer 20 when no voltage is applied, the in-plane slow axis 41SA of the λ / 4 plate 41, the in-plane slow axis 42SA of the λ / 2 plate 42, and the polarization axis 50AA of the polarizing plate 50. [Figure 12]In a liquid crystal display device 1 having, in order from the rear side, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a λ / 4 plate 41, a λ / 2 plate 42, and a polarizing plate 50, this is a plan view conceptually showing the relationship between the long axis direction of liquid crystal molecules 21 in the liquid crystal layer 20 when no voltage is applied, the in-plane slow axis 41SA of the λ / 4 plate 41, the in-plane slow axis 42SA of the λ / 2 plate 42, and the polarization axis 50AA of the polarizing plate 50. [Figure 13] 10 is a schematic cross-sectional view showing in more detail the liquid crystal display device 1 of Modification 1 of Embodiment 2. FIG. [Figure 14] 1 is a schematic cross-sectional view of a liquid crystal display device 1 according to an example of embodiment 3. FIG. [Figure 15] FIG. 11 is a plan view conceptually illustrating that each pixel P has a reflective region Rf and a transmissive region Tr in the liquid crystal display device 1 of Embodiment 3. [Figure 16] 1 is a schematic cross-sectional view of a liquid crystal display device 1 according to an example of embodiment 4. FIG. [Figure 17A] FIG. 2 is a schematic cross-sectional view of the device prepared in Verification Example 1. [Figure 17B] FIG. 2 is a schematic cross-sectional view of the device assumed in Test Examples 1 and 2. [Figure 18] 1 is a CAD diagram showing, in plan view, only the pixel electrodes PE and the common electrode CE on the TFT substrate side. [Figure 19] 1 is an image (planar image) of the inside of the device observed with a microscope in Verification Example 1. [Figure 20A] 1 is a plan view of the initial state of the device taken from the observation surface side in Verification Example 1. [Figure 20B] This is a planar photograph taken from the observation surface side of a device in its initial state in verification example 1, with black characters written on it. [Figure 20C] This is a flat photograph taken from the observation surface side in verification example 1 after the written characters have been erased. [Figure 21] FIG. 1 is a plan view conceptually showing that the rotation direction of liquid crystal molecules 21 (negative liquid crystal) is different between the pixel center (a) and the pixel edge (b). [Figure 22] FIG. 18 is a diagram in which conceptual diagrams showing the rotation directions of liquid crystal molecules 21 are superimposed. [Figure 23] FIG. 19 is a diagram in which conceptual diagrams showing the rotation directions of liquid crystal molecules 21 are superimposed. [Figure 24A] 1A is a diagram showing a simulation result of Test Example 1 (see (a)), and (b) is a diagram showing a concept of a plurality of band-like portions SP based on the simulation result (see (a)). [Figure 24B] 13A is a diagram showing the results of a simulation of Test Example 2 (see FIG. 13A), and FIG. 13B is a diagram showing a concept of a plurality of band-like portions SP based on the results (see FIG. 13B). [Diagram 25] 1 is a schematic cross-sectional view of a liquid crystal panel 1X included in a device assumed in Test Examples 3 and 4. FIG. [Figure 26] 2 is a schematic diagram conceptually showing an electrode structure of a pixel electrode PE and a common electrode CE. FIG. [Figure 27] FIG. 11 is a plan view conceptually showing the axial settings of each optical film used in Test Example 3. [Figure 28] FIG. 11 is a plan view conceptually showing the axial settings of each optical film used in Test Example 4. [Figure 29] 1 is a graph showing the results of Test Example 3. [Diagram 30] 1 is a graph showing the results of Test Example 4. [Diagram 31] FIG. 11 is a plan view conceptually showing the axial settings of each optical film used in Test Example 5. [Diagram 32] FIG. 11 is a plan view conceptually showing the axial settings of each optical film used in Test Example 6. [Diagram 33] 1 is a graph showing the results of Test Example 5. [Diagram 34] 1 is a graph showing the results of Test Example 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] (Definition of terms) In this specification, the observation side means the side closer to the screen (display surface) of the liquid crystal display device, and the rear side means the side farther from the screen (display surface) of the liquid crystal display device.

[0032] The no-voltage-applied state refers to a state in which the voltage applied to the liquid crystal layer is less than the threshold voltage (including no voltage application). The voltage-applied state refers to a state in which the voltage applied to the liquid crystal layer is equal to or greater than the threshold voltage. In this specification, the no-voltage-applied state is also referred to as when no voltage is applied, and the voltage-applied state is also referred to as when a voltage is applied.

[0033] The polar angle means the angle between the direction of interest (for example, the measurement direction) and the normal direction of the screen of the liquid crystal panel. The azimuth refers to the direction when the target direction is projected onto the screen of the liquid crystal panel, and is expressed as the angle (azimuth angle) between the target direction and a reference direction. Here, the reference direction (0°) is set to the horizontal right direction on the screen of the liquid crystal panel. For angles and azimuth angles, positive angles are counterclockwise from the reference orientation, and negative angles are clockwise from the reference orientation. Both counterclockwise and clockwise refer to the direction of rotation when the LCD panel screen is viewed from the observation side (front). Additionally, angles refer to values ​​measured when the LCD panel screen is viewed in a flat view, and refer to acute angles unless otherwise specified, such as the direction of rotation.

[0034] The axial direction of the optical film means the direction of the polarization axis of the polarizing plate if it is a polarizing plate, and means the direction of the slow axis if it is a retardation layer. The polarization axis of the polarizing plate means the absorption axis if it is an absorption type polarizing plate, and means the reflection axis if it is a reflection type polarizing plate. The axial direction of the retardation layer means the direction of the in-plane slow axis of the retardation layer, unless otherwise specified.

[0035] The retardation layer means a layer having at least one of the in-plane retardation (also called in-plane retardation) Re and the thickness direction retardation (also called thickness direction retardation) Rth of 10 nm or more.Preferably, it means a layer having a value of 20 nm or more.In this specification, the numerical values ​​described as Re and Rth are absolute values ​​unless otherwise specified.

[0036] The in-plane retardation Re is defined as Re=(nx-ny)×d. The thickness direction retardation Rth is defined as Rth={nz-(nx+ny) / 2}×d. nx represents the principal refractive index in the slow axis direction in the plane of each retardation layer. ny represents the principal refractive index in the fast axis direction in the plane of each retardation layer. nz represents the principal refractive index in the direction perpendicular to the surface of each retardation layer. The slow axis direction is the direction in which the refractive index is maximum, and the fast axis direction is the direction in which the refractive index is minimum. d represents the thickness of the retardation layer.

[0037] An A plate is a retardation plate that satisfies "nx>ny≒nz."

[0038] The measurement wavelength for optical parameters such as refractive index and phase difference is 550 nm unless otherwise specified.

[0039] "Approximately parallel" means that the angle (absolute value) between the two is within the range of 0°±10°, and this angle is preferably within the range of 0°±5°, and more preferably 0° (i.e., parallel in the narrow sense). "Approximately perpendicular" (or approximately perpendicular) means that the angle (absolute value) between the two is within the range of 90°±10°, and this angle is preferably within the range of 90°±5°, and more preferably 90° (i.e., orthogonal or perpendicular in the narrow sense).

[0040] Hereinafter, a liquid crystal display device according to an embodiment of the present invention will be described. The present invention is not limited to the contents described in the following embodiment, and appropriate design changes can be made within the scope of the configuration of the present invention.

[0041] (Embodiment 1) FIG. 1 is a schematic cross-sectional view of a liquid crystal display device 1 according to an example of the present embodiment, and FIG. 2 is a schematic cross-sectional view showing the liquid crystal display device 1 according to an example of the present embodiment in more detail. FIG. 3 is a schematic plan view of the entire liquid crystal display device 1 according to an example of the present embodiment, as viewed from the observation surface side. As shown in FIG. 1, the liquid crystal display device 1 includes, in order from the rear side, a first substrate 10, a liquid crystal layer 20, and a second substrate 30. In this embodiment, a TFT substrate is used as the first substrate 10. Note that a portion or structure having a structure in which the liquid crystal layer 20 is sandwiched between the first substrate 10 and the second substrate 30 is also referred to as a liquid crystal panel 1X.

[0042] As shown in Fig. 3, the liquid crystal display device 1 has a plurality of pixels P arranged in a matrix. The plurality of pixels P typically include three types of pixels, namely red pixels, green pixels, and blue pixels, but the number of types of pixels may be two or less, or may be four or more. Each pixel P includes a thin film transistor (TFT) 110, and a first electrode 121 and a second electrode 122 capable of generating a transverse electric field in the liquid crystal layer 20. A gate electrode of the TFT 110 is electrically connected to a corresponding gate line (also referred to as a scanning line) GL, and a source electrode of the TFT 110 is electrically connected to a corresponding source line (also referred to as a signal line) SL. A drain electrode of the TFT 110 is electrically connected to the second electrode 122.

[0043] <First substrate> As shown in FIG. 2, the first substrate 10 has, in order from the back side to the observation side, a reflective layer 130 that reflects light, a first electrode 121, a second electrode 122, and a first horizontal alignment film 140 that contacts the liquid crystal layer 20. The first substrate 10 preferably further has a support substrate 100 and a backplane circuit BP on the back side of the reflective layer 130. An insulating layer (also called an insulating film) is provided between each layer, etc., as necessary. For example, a first interlayer insulating layer 151 is provided so as to cover the backplane circuit BP, a second interlayer insulating layer 152 is provided on the first interlayer insulating layer 151 with the reflective layer 130 sandwiched therebetween, and a dielectric layer (also called a third interlayer insulating layer) 153 is provided between the first electrode 121 and the second electrode 122.

[0044] The supporting substrate 100 is preferably transparent and insulating, and examples of the supporting substrate 100 include a glass substrate and a plastic substrate.

[0045] The backplane circuit BP is provided on a support substrate 100. The backplane circuit BP is a circuit for driving a plurality of pixels P, and includes a TFT 110, a gate line GL, a source line SL, etc. Usually, the backplane circuit BP also includes a gate insulating film 150G.

[0046] The TFT 110 is provided in each of the pixels P. The TFT 110 is preferably one including an oxide semiconductor layer as an active layer (also referred to as an oxide semiconductor TFT). The oxide semiconductor included in the oxide semiconductor layer has been attracting attention in recent years as an active layer material to replace amorphous silicon and polycrystalline silicon, and has a higher mobility than amorphous silicon. Therefore, the oxide semiconductor TFT can operate at a higher speed than the amorphous silicon TFT. In addition, the oxide semiconductor layer can be formed by a simpler process than the polycrystalline silicon layer, and can be applied to devices requiring a large area.

[0047] Since oxide semiconductor TFTs also have excellent off-leak characteristics, a driving method can be used to display images by reducing the frequency of rewriting. For example, when displaying a still image, image data can be rewritten once per second. This type of driving method is called pause driving or low-frequency driving, and can significantly reduce the power consumption of a liquid crystal display device. By employing pause driving and performing touch detection during periods when images are not being rewritten, it is possible to suppress a decrease in sensitivity of touch operations due to noise from the driving circuit, and the S / N ratio (signal-to-noise ratio) can be increased, for example, to about 10 times that of conventional devices.

[0048] The oxide semiconductor TFT is also advantageous in terms of reducing the size of the TFT, and therefore can suitably realize a configuration in which a memory circuit is provided for each pixel P (also referred to as MIP (Memory In Pixels)).

[0049] The oxide semiconductor may be an amorphous oxide semiconductor or a crystalline oxide semiconductor having a crystalline portion. Examples of the crystalline oxide semiconductor include a polycrystalline oxide semiconductor, a microcrystalline oxide semiconductor, and a crystalline oxide semiconductor whose c-axis is oriented substantially perpendicular to the layer surface.

[0050] The oxide semiconductor layer may be a single layer or may have a laminated structure of two or more layers. The oxide semiconductor layer having a laminated structure may include an amorphous oxide semiconductor layer and a crystalline oxide semiconductor layer, may include a plurality of crystalline oxide semiconductor layers having different crystal structures, or may include a plurality of amorphous oxide semiconductor layers. When the oxide semiconductor layer has a two-layer structure including an upper layer and a lower layer, the energy gap of the oxide semiconductor included in the lower layer may be different from the energy gap of the oxide semiconductor included in the upper layer.

[0051] The materials and structures of the amorphous oxide semiconductor and each crystalline oxide semiconductor, the film formation method, and the configuration of the oxide semiconductor layer having a laminated structure are described in, for example, JP 2014-007399 A. For reference, the entire disclosure of JP 2014-007399 A is incorporated herein by reference.

[0052] Specifically, the oxide semiconductor layer preferably contains at least one metal element selected from In (indium), Ga (gallium), and Zn (zinc). Among them, an oxide semiconductor film containing a ternary oxide of In, Ga, and Zn is more preferable. A preferred example of the ternary oxide of In, Ga, and Zn is indium gallium zinc oxide. A semiconductor containing a ternary oxide of In, Ga, and Zn is called an In-Ga-Zn-O-based semiconductor, and the ratio (composition ratio) of In, Ga, and Zn in this semiconductor is not particularly limited, and examples thereof include In:Ga:Zn=2:2:1, In:Ga:Zn=1:1:1, and In:Ga:Zn=1:1:2.

[0053] The In-Ga-Zn-O based semiconductor may be amorphous or crystalline. As a crystalline In-Ga-Zn-O based semiconductor, one in which the c-axis is oriented approximately perpendicular to the layer surface is preferable.

[0054] The crystal structure of the crystalline In-Ga-Zn-O-based semiconductor is disclosed in, for example, JP 2014-007399 A, JP 2012-134475 A, JP 2014-209727 A, etc. For reference, the entire disclosures of JP 2012-134475 A and JP 2014-209727 A are incorporated herein by reference. Since a TFT having an In-Ga-Zn-O-based semiconductor layer has high mobility (more than 20 times that of an a-Si TFT) and low leakage current (less than 1 / 100 that of an a-Si TFT), it is suitable for use as a driving TFT (for example, a TFT included in a driving circuit provided on the same substrate as the display area around a display area including a plurality of pixels) and a pixel TFT (a TFT provided in a pixel).

[0055] The oxide semiconductor layer may contain an oxide semiconductor other than an In-Ga-Zn-O-based semiconductor. For example, a ternary oxide of In, Sn (tin) and Zn may be mentioned, and for example, In2O3-SnO2-ZnO; InSnZnO is preferably exemplified. A semiconductor containing a ternary oxide of In, Sn and Zn is called an In-Sn-Zn-O-based semiconductor. Alternatively, the oxide semiconductor layer may include an In-Al-Zn-O based semiconductor, an In-Al-Sn-Zn-O based semiconductor, a Zn-O based semiconductor, an In-Zn-O based semiconductor, a Zn-Ti-O based semiconductor, a Cd-Ge-O based semiconductor, a Cd-Pb-O based semiconductor, CdO (cadmium oxide), an Mg-Zn-O based semiconductor, an In-Ga-Sn-O based semiconductor, an In-Ga-O based semiconductor, a Zr-In-Zn-O based semiconductor, an Hf-In-Zn-O based semiconductor, an Al-Ga-Zn-O based semiconductor, a Ga-Zn-O based semiconductor, an In-Ga-Zn-Sn-O based semiconductor, or the like.

[0056] The first interlayer insulating layer 151 is provided so as to cover the backplane circuit BP. The surface of the first interlayer insulating layer 151 on the reflective layer 130 side preferably has an uneven shape (also referred to as an uneven surface structure). This allows the reflective layer 130 to have an uneven surface structure that reflects this shape. The first interlayer insulating layer 151 having an uneven surface structure can be suitably formed using a photosensitive resin, for example, as described in Japanese Patent No. 3394926.

[0057] The reflective layer (also referred to as a reflective film) 130 is provided on the first interlayer insulating layer 151. The reflective layer 130 is formed from a material that reflects light. In particular, it is preferable that the reflective layer 130 is formed from a metal material having a high reflectance. Examples of materials for the reflective layer 130 include a silver alloy, an aluminum alloy, and an aluminum alloy.

[0058] The reflective layer 130 preferably has an uneven shape that reflects the uneven surface structure that the first interlayer insulating layer 151 preferably has. That is, the reflective layer 130 also preferably has an uneven surface structure. This uneven surface structure is also called MRS (Micro Reflective Structure) and is provided to diffusely reflect ambient light and realize a white display close to paper white. The uneven surface structure is preferably composed of a plurality of convex parts p arranged randomly so that the center distance between adjacent convex parts p is 5 μm or more and 50 μm or less. The center distance between adjacent convex parts p is more preferably 10 μm or more and 20 μm or less. The shape of the convex parts p is preferably approximately circular or approximately polygonal when viewed from the normal direction of the support substrate. The area of ​​the convex parts p that occupies one pixel P is preferably, for example, about 20 to 40%, and the height of the convex parts p is preferably, for example, 1 μm or more and 5 μm or less.

[0059] By providing the reflective layer 130 and introducing a retardation layer with a broadband λ / 4 condition, polarization conversion (for example, conversion between circularly polarized light and linearly polarized light) specific to reflective liquid crystal display devices becomes possible, so that light loss is sufficiently reduced. The broadband λ / 4 condition is a condition under which polarized light close to circularly polarized light can be obtained over a wide range of visible wavelengths.

[0060] The second interlayer insulating layer 152 is provided on the first interlayer insulating layer 151 so as to cover the reflective layer 130. That is, the reflective layer 130 is disposed between the first interlayer insulating layer 151 and the second interlayer insulating layer 152.

[0061] Here, the first interlayer insulating layer 151 and the second interlayer insulating layer 152 are preferably formed from an organic insulating material or an inorganic insulating material. For example, organic insulating films obtained using an organic insulating material include organic films (relative dielectric constant ε=2 to 5) of acrylic resin, polyimide resin, novolac resin, etc., and laminates thereof. The thickness of the organic insulating film is not particularly limited, but is, for example, 2 μm or more and 4 μm or less. For example, inorganic insulating films obtained using an inorganic insulating material include inorganic films (relative dielectric constant ε=5 to 7) of silicon nitride (SiNx), silicon oxide (SiO2), etc., and laminates thereof. The thickness of the inorganic insulating film is not particularly limited, but is, for example, 1500 Å or more and 3500 Å or less. Alternatively, the inorganic insulating film may be a laminate of an organic insulating film and an inorganic insulating film. Among them, it is preferable that the first interlayer insulating layer 151 and the second interlayer insulating layer 152 are organic insulating films.

[0062] The first electrode 121 is disposed on the reflective layer 130 via the second interlayer insulating layer 152, and a dielectric layer 153 is disposed between the first electrode 121 and the second electrode 122. Therefore, the reflective layer 130 is located on the opposite side of the liquid crystal layer 20 with respect to the first electrode 121 and the second electrode 122 (i.e., on the rear side of the first electrode 121 and the second electrode 122). In this embodiment, of the first electrode 121 and the second electrode 122, the second electrode 122 is located relatively closer to the observation surface, and the first electrode 121 is located on the rear surface. The electrode located relatively closer to the observation surface is also referred to as an upper layer electrode, and the electrode located relatively closer to the rear surface is also referred to as a lower layer electrode.

[0063] One of the first electrode 121 and the second electrode 122 is a pixel electrode PE, and the other is a common electrode CE. The pixel electrode is provided in each of the multiple pixels P. The pixel electrode is electrically connected to the backplane circuit BP. In this embodiment, the first electrode 121 (lower layer electrode) is the common electrode CE, and the second electrode 122 (upper layer electrode) is the pixel electrode PE.

[0064] At least one of the first electrode 121 and the second electrode 122 has a plurality of strip portions SP and a slit Sl located between two adjacent strip portions of the plurality of strip portions. The strip portions SP correspond to electrode portions, and the slits Sl correspond to openings, and such electrodes are also called slit electrodes or finger electrodes. From the viewpoint of easily generating a transverse electric field, it is preferable that at least the upper layer electrode (pixel electrode PE in this embodiment) is a slit electrode. In this case, the lower layer electrode (common electrode CE in this embodiment) may be a planar electrode, that is, a so-called solid electrode, or may be a slit electrode.

[0065] In each pixel P, the strip portions SP constituting the slit electrode (in this embodiment, the second electrode 122 which is the pixel electrode PE) are linearly shaped and extend in the same direction in parallel to each other, and do not include any bent portions. This makes the alignment of the liquid crystal molecules uniform, and sufficiently suppresses the occurrence of alignment disturbance.

[0066] Here, the band-shaped portion SP being "linear and not including a bent portion" means that the center line of the band-shaped portion SP, not the outer edge of the band-shaped portion SP, is linear and not bent. The center line of the band-shaped portion SP means a line that divides the band-shaped portion SP into two equal parts in the width direction. The width direction means a direction that is approximately perpendicular to the direction in which the band-shaped portion SP extends in a plan view. Therefore, even if the outer edge of the tip of the band-shaped portion SP is circular, if the center line of the band-shaped portion SP is a straight line that is not bent, it is included in the shape of "linear and not including a bent portion". For comparison, the shape of the band-shaped portion SP when it includes a bent portion is shown in FIG. 24A (b), and the shape of the band-shaped portion SP when it does not include a bent portion is shown in FIG. 24B (b).

[0067] It is also preferable that the strip portion SP does not include a cutout portion. This further suppresses the occurrence of alignment disturbance. "The strip portion SP does not include a cutout portion" means that no part of the strip portion SP is cut out or removed.

[0068] In each pixel P, the directions in which the strip portions SP extend (also referred to as the extension directions of the strip portions SP) are approximately parallel to one another. The extension directions of the strip portions SP may differ for each pixel, but are preferably the same for two or more adjacent pixels. In particular, from the viewpoints of image quality and manufacturing, it is more preferable that the extension directions of the strip portions SP are the same at least for adjacent pixels. Each of Figs. 6A to 6F described later shows an example in which the extension directions of the strip portions SP are the same for adjacent pixels. It is also more preferable that the extension directions of the strip portions SP are the same in the display area.

[0069] The width L of each stripe portion SP is preferably, for example, 0.3 to 10 μm, and more preferably 1 to 5 μm. The interval between two adjacent stripe portions SP (i.e., the interval between the center lines of each stripe portion) is also preferably, for example, 0.3 to 10 μm, and more preferably 1 to 5 μm.

[0070] The ratio L / S (also referred to as the L / S condition) of the width L of each belt-like portion in a plan view to the width S of each slit in a plan view is preferably 0.4 to 0.7 / 1, thereby improving the reflectance of white display (also referred to as the white reflectance), and thus the contrast ratio.

[0071] Here, the alignment direction of the liquid crystal molecules 21 on the first substrate 10 side when no voltage is applied is preferably −30° or more and 30° or less with respect to the extension direction of the strip portions SP as the reference (0°). This angle, that is, the angle formed by the alignment direction of the liquid crystal molecules 21 on the first substrate 10 side when no voltage is applied, when the extension direction of the strip portions SP is the reference (0°) and the angle rotated clockwise is a positive angle (+) and the angle rotated counterclockwise is a negative angle (-), is called the slit angle. The definition of the slit angle will be described with reference to FIG. 4A and FIG. 4B. FIG. 4A is a diagram for explaining the slit angle of positive-type liquid crystal molecules, and FIG. 4B is a diagram for explaining the slit angle of negative-type liquid crystal molecules. Liquid crystal molecule 21A refers to the liquid crystal molecule 21 near the first horizontal alignment film 140 (i.e., the liquid crystal molecule on the first substrate 10 side when no voltage is applied), and the (p) and (n) suffixes to the symbols for the liquid crystal molecules refer to positive type and negative type, respectively.

[0072] In the case of positive-type liquid crystal molecules, the alignment direction of the liquid crystal molecules 21A on the first substrate 10 side when no voltage is applied corresponds to the long axis direction of the liquid crystal molecules 21A. When the long axis direction of the liquid crystal molecules 21A and the extension direction of the strip portions SP are parallel to each other, the slit angle is 0° (see the "0°" column in FIG. 4A). When the extension direction of the strip portions SP rotates clockwise with the long axis direction of the liquid crystal molecules 21A as the reference (0°), the slit angle is a positive angle (+) (see the "Positive (+)" column in FIG. 4A). When the extension direction of the strip portions SP rotates counterclockwise with the long axis direction of the liquid crystal molecules 21A as the reference (0°), the slit angle is a negative angle (-) (see the "Negative (-)" column in FIG. 4A).

[0073] In the case of negative type liquid crystal molecules, the alignment direction of the liquid crystal molecules 21A on the first substrate 10 side when no voltage is applied corresponds to the short axis direction of the liquid crystal molecules 21A. When the short axis direction of the liquid crystal molecules 21A and the extension direction of the strip portions SP are parallel, the slit angle is 0° (see the "0°" column in FIG. 4B). When the extension direction of the strip portions SP rotates clockwise with the short axis direction of the liquid crystal molecules 21A as the reference (0°), the slit angle is a positive angle (+) (see the "Positive (+)" column in FIG. 4B). When the extension direction of the strip portions SP rotates counterclockwise with the short axis direction of the liquid crystal molecules 21A as the reference (0°), the slit angle is a negative angle (-) (see the "Negative (-)" column in FIG. 4B).

[0074] Therefore, the slit angle can also be said to be the angle formed by the axis of the liquid crystal molecule 21A on the first substrate 10 side with the extension direction of the multiple strip-shaped portions as the reference (0°) and the axis having the larger absolute value of the dielectric constant when no voltage is applied.

[0075] The suitable range of the slit angle varies depending on the condition of the width L of each belt-shaped portion SP and the width S of each slit Sl (also called the L / S condition), the twist angle, whether the liquid crystal material is positive type or negative type, etc. In particular, with a monodomain structure, the reflectance (especially the white reflectance) can be maximized by selecting the optimal slit angle depending on the L / S condition.

[0076] For example, when a positive type liquid crystal material is used and the twist angle is 74°, under the condition of L / S (μm) = 2.2 / 4.1 (i.e., L / S = 0.537 / 1), the preferred range of the slit angle is -25° to +18°, more preferably -18° to +9°, and even more preferably -11.5° to +2° (see Test Example 3-1 described later). Under the condition of L / S (μm) = 1.6 / 3.0 (i.e., L / S = 0.533 / 1), the preferred range of the slit angle is -18° to +14°, more preferably -11° to +9°, and even more preferably -9.5° to 0° (see Test Example 3-2 described later). Under the condition of L / S (μm)=3.0 / 5.0 (i.e., L / S=0.6 / 1), the preferred range of the slit angle is −25° to +13°, and a more preferred range is −13° to +5° (see Test Example 3-3 described later).

[0077] For example, when a negative type liquid crystal material is used and the twist angle is 74°, the preferred range of the slit angle is −30° to +5°, and more preferably −28° to −3°, under the condition of L / S (μm) = 2.2 / 4.1 (i.e., L / S = 0.537 / 1) (see Test Example 4-1 described later). Under the condition of L / S (μm) = 1.6 / 3.0 (i.e., L / S = 0.533 / 1), the preferred range of the slit angle is −25° to +3°, and more preferably −15° to −7° (see Test Example 4-2 described later). Under the condition of L / S (μm) = 3.0 / 5.0 (i.e., L / S = 0.6 / 1), the preferred range of the slit angle is −30° to 0°, and more preferably −22° to −10° (see Test Example 4-3 described later).

[0078] For example, when a positive type liquid crystal material is used and the twist angle is 83°, under the condition of L / S (μm) = 2.2 / 4.1 (i.e., L / S = 0.537 / 1), the preferred range of the slit angle is -27° to +16°, more preferably -18° to +10°, and even more preferably -11.5° to 0° (see Test Example 5-1 described later). Under the condition of L / S (μm) = 1.6 / 3.0 (i.e., L / S = 0.533 / 1), the preferred range of the slit angle is -20° to +13°, more preferably -12° to +7°, and even more preferably -9.5° to 0° (see Test Example 5-2 described later). Under the condition of L / S (μm)=3.0 / 5.0 (i.e., L / S=0.6 / 1), the preferred range of the slit angle is −27° to +13°, and a more preferred range is −18° to +8° (see Test Example 5-3 described later).

[0079] For example, when a negative type liquid crystal material is used and the twist angle is 83°, under the condition of L / S (μm) = 2.2 / 4.1 (i.e., L / S = 0.537 / 1), the preferred range of the slit angle is -30° to +5°, more preferably -30° to -7°, and even more preferably -19° to -12° (see Test Example 6-1 described below). Under the condition of L / S (μm) = 1.6 / 3.0 (i.e., L / S = 0.533 / 1), the preferred range of the slit angle is -30° to +3°, and more preferably -15° to -5° (see Test Example 6-2 described below). Under the condition of L / S (μm)=3.0 / 5.0 (i.e., L / S=0.6 / 1), the preferred range of the slit angle is −30° to +2°, and more preferably −30° to −5° (see Test Example 6-3 described later).

[0080] 5 and 6A show an example in which the extension direction of the strip portions SP is 0° (this angle is referred to as angle X) when the extension direction of the source wiring SL is taken as the reference (0°), and the angle rotated clockwise is taken as a positive angle (+), and the angle rotated counterclockwise is taken as a negative angle (-). Also, examples in which the angle X is -10°, +10°, -90°, -100°, and -80° are shown in Figs. 6B, 6C, 6D, 6E, and 6F, respectively. The aspect in which the angle X is 0° (see Figs. 5 and 6A) corresponds to an aspect in which the extension direction of the strip portions SP is parallel to the extension direction of the source wiring SL, and the aspect in which the angle X is -90° (see Fig. 6D) corresponds to an aspect in which the extension direction of the strip portions SP is parallel to the extension direction of the gate wiring GL.

[0081] FIG. 5 and FIG. 6A to FIG. 6F are schematic plan views showing specific examples of pixels. FIG. 5 is a schematic plan view showing an example of a pixel structure, and FIG. 6A to FIG. 6F are schematic plan views showing an example of a pixel arrangement. FIG. 6A to FIG. 6F also show the twisted orientation of the liquid crystal molecules 21. The liquid crystal molecules 21A refer to the liquid crystal molecules 21 in the vicinity of the first horizontal alignment film 140 (i.e., the liquid crystal molecules on the first substrate 10 side when no voltage is applied), and the liquid crystal molecules 21B refer to the liquid crystal molecules 21 in the vicinity of the second horizontal alignment film 340 (i.e., the liquid crystal molecules on the second substrate 30 side when a voltage is applied). The (p) and (n) suffixed to the symbols of the liquid crystal molecules refer to a positive type and a negative type, respectively.

[0082] In the present embodiment, the pixel electrode PE is provided above the common electrode CE. However, in a relatively large liquid crystal display device, that is, in a liquid crystal display device in which the area of ​​the pixel P is relatively large, it is preferable that the pixel electrode PE is provided above the common electrode CE. In this configuration (also referred to as the V2 structure), since there is no need to form a slit in the common electrode CE, which is the lower electrode, the increase in resistivity (sheet resistivity) of the common electrode CE is suppressed more than in the configuration (also referred to as the V3 structure) in which the common electrode CE is provided above the pixel electrode PE, and therefore the fringe electric field applied to the liquid crystal layer 20 is suppressed from weakening. In this configuration (V2 structure), when the pixel electrode PE is a slit electrode, the resistivity of the pixel electrode PE increases, but since an externally input voltage is applied to the pixel electrode PE, it is easy to reduce the effect of the increase in resistivity (i.e., to suppress the fringe electric field from weakening). In order to suppress the increase in resistivity of the common electrode CE, it is possible to use low-resistance wiring made of a metal material (for example, connecting the low-resistance wiring to the common electrode). However, in such a configuration, adverse effects on the display due to specular reflection from the low-resistance wiring (for example, glare, rainbow-colored diffraction, interference patterns) may occur, making it necessary to block light with a black matrix or the like, and it may not be possible to sufficiently improve the reflective aperture ratio.

[0083] In the configuration in which the pixel electrode PE is provided above the common electrode CE, the common electrode CE is not present in the region in which the second contact hole CH2 is formed, and the region does not contribute to reflective display, so that the reflectance may be lower than in the configuration in which the common electrode CE is provided above the pixel electrode PE. Since the area of ​​the region that does not contribute to reflective display, such as the contact hole, is required to a certain extent regardless of the size of the area of ​​the pixel P, the ratio of the region that does not contribute to reflective display in the pixel P increases as the area of ​​the pixel P decreases (i.e., the resolution increases), and the above-mentioned decrease in reflectance increases. In other words, in a relatively large liquid crystal display device, the ratio of the region that does not contribute to reflective display in the pixel P is easier to reduce, so that the above-mentioned decrease in reflectance is easier to suppress. For these reasons, in a relatively large liquid crystal display device, a configuration in which the pixel electrode PE is provided above the common electrode CE is advantageous.

[0084] On the other hand, as described above, the reduction in reflectance due to the region in which the second contact hole CH2 is formed not contributing to the reflective display becomes greater as the area of ​​the pixel P becomes smaller (i.e., as the resolution increases). Therefore, in a relatively high-resolution liquid crystal display device, i.e., a liquid crystal display device in which the area of ​​the pixel P is relatively small, it is preferable that the common electrode CE is provided above the pixel electrode PE (see Variant 1 of Embodiment 1 described below).

[0085] The first electrode 121 and the second electrode 122 are preferably each made of a transparent conductive material, such as indium tin oxide (ITO), indium zinc oxide (IZO (registered trademark)), a mixture thereof, or the like.

[0086] In the embodiment shown in FIG. 2, the pixel electrode PE (the second electrode 122 in this embodiment) is electrically connected to the backplane circuit (more specifically, to the drain electrode of the TFT 110) via the contact electrode 160. The contact electrode 160 is formed in the same layer as the reflective film 130 and is made of the same material (metal film, etc.) as the reflective film 130. The first interlayer insulating layer 151 is formed with a first contact hole CH1 that exposes a part of the backplane circuit BP (more specifically, at least a part of the drain electrode of the TFT 110), and the contact electrode 160 is connected to the backplane circuit BP at the first contact hole CH1. The second interlayer insulating layer 152 is formed with a second contact hole CH2 that exposes a part of the contact electrode 160, and the pixel electrode PE (the second electrode 122 in this embodiment) is connected to the contact electrode 160 at the second contact hole CH2.

[0087] The dielectric layer 153 is provided so as to cover the first electrode 121. The dielectric layer 153 is preferably formed from an inorganic insulating material. The inorganic insulating film obtained using the inorganic insulating material is as described above.

[0088] The first horizontal alignment film 140 is provided on the second electrode 122 and is in contact with the liquid crystal layer 20. Therefore, it can be said that the first electrode 121 and the second electrode 122 are disposed between the second interlayer insulating layer 152 and the first horizontal alignment film 140.

[0089] The first horizontal alignment film 140 and the second horizontal alignment film 340 described later are each subjected to an alignment treatment, and define the alignment direction (also referred to as the alignment direction) of the liquid crystal molecules 21 contained in the liquid crystal layer 20. For example, the alignment treatment is preferably performed by a photo-alignment treatment or a rubbing treatment. In the photo-alignment treatment, a photodecomposition type photo-alignment film material can be used, and in the rubbing treatment, it is preferable to use an alignment film material such as polyimide.

[0090] Both the first horizontal alignment film 140 and the second horizontal alignment film 340 are horizontal alignment films that align the liquid crystal molecules 21 in a direction horizontal to the first substrate 10 and the second substrate 30 when no voltage is applied to the liquid crystal layer 20. That is, the liquid crystal molecules 21 are horizontally aligned when no voltage is applied to the liquid crystal layer 20. The pretilt angle is substantially 0°.

[0091] The alignment direction of the liquid crystal molecules 21 determined by the first horizontal alignment film 140 is different from the alignment direction of the liquid crystal molecules 21 determined by the second horizontal alignment film 340. Therefore, the liquid crystal layer 20 has a twisted alignment when no voltage is applied (see FIG. 2). When a voltage is applied to the liquid crystal layer 20, that is, when a transverse electric field is generated in the liquid crystal layer 20 by the first electrode 121 and the second electrode 122, the alignment state of the liquid crystal layer 20 changes due to the transverse electric field (fringe electric field).

[0092] <Liquid crystal layer> The liquid crystal layer 20 is located between the first substrate 10 and the second substrate 30, and contains a positive type liquid crystal material or a negative type liquid crystal material. The positive type liquid crystal material means a nematic liquid crystal material having a positive dielectric anisotropy Δε, and the negative type liquid crystal material means a nematic liquid crystal material having a negative dielectric anisotropy Δε. The dielectric anisotropy Δε is the dielectric constant ε in the long axis direction of the liquid crystal molecules 21. / / and the dielectric constant in the minor axis direction ε ⊥(i.e., ε / / -ε ⊥ ).

[0093] In the case of a positive-type liquid crystal material, the birefringence Δn of the liquid crystal material is, for example, preferably 0.123 or less, more preferably 0.12, and even more preferably 0.119 or less. From the viewpoint of manufacturing (yield rate, etc.), the thickness d of the liquid crystal layer 20 is preferably 2 μm or more, and in this case, it is suitable that Δn is 0.123 or less. More preferably, d is 2.5 μm or more and Δn is 0.098 or less. However, from the viewpoint of response, a smaller cell thickness is preferable. Also, the dielectric anisotropy Δε of the liquid crystal material is preferably, for example, 10 or more.

[0094] In the case of a negative type liquid crystal material, the birefringence Δn of the liquid crystal material is preferably, for example, 0.123 or less, and more preferably 0.12. In particular, it is suitable that the thickness d of the liquid crystal layer 20 is 2 μm or more and Δn is 0.123 or less. More preferably, d is 2.5 μm or more and Δn is 0.098 or less. In addition, it is preferable that the dielectric anisotropy Δε of the liquid crystal material is, for example, -5 or less. Note that the smaller Δε (or the larger the absolute value of Δε), the more the VR curve (threshold value, maximum reflectance value, etc.) shifts to the low voltage side.

[0095] When selecting positive or negative type, it is preferable to consider the application and desired performance. For example, from the viewpoint of realizing flickerless (also called flicker-free), it is preferable to use a negative type liquid crystal material. This is for the following reason. In the in-plane electric field method of FFS mode using positive type liquid crystal material, flexopolarization occurs spontaneously in the liquid crystal layer due to the influence of fine slit electrodes on the electrodes (i.e., fringe electric field) when voltage is applied. Since the liquid crystal responds according to this flexopolarization, the luminance changes when the polarity is inverted, which is considered to be easily recognized as flicker. In addition, from the viewpoint of reliability, it is preferable to use a positive type liquid crystal material.

[0096] The liquid crystal layer 20 may further include a chiral agent, if necessary. The liquid crystal layer 20 can be formed by, for example, a dropping method.

[0097] The thickness d of the liquid crystal layer 20 (also referred to as the cell gap or cell thickness) is preferably, for example, 3.6 μm or less. More preferably, it is 2.0 to 3.4 μm. From the viewpoint of response speed, it is preferably 3 μm or less. A smaller cell thickness is preferable from the viewpoint of cost reduction, since it allows the number of materials to be reduced. However, if it is too small, the display quality may not be improved due to unevenness in the cell thickness or foreign matter, resulting in a trade-off with the occurrence rate of defective display quality. From the viewpoint of yield, it is preferable that the cell thickness is 2 μm or more, as described above.

[0098] From the viewpoint of suppressing alignment disturbance, the liquid crystal layer 20 is preferably in a single domain alignment (also referred to as monodomain alignment).

[0099] <Second board> The second substrate 30 is disposed opposite the first substrate 10 with the liquid crystal layer 20 interposed therebetween, and has a second horizontal alignment film 340 in contact with the liquid crystal layer 20. The second substrate 30 preferably further has a support substrate 300 and a color filter layer 310. For example, as shown in FIG. 2, the second substrate 30 has, in order from the liquid crystal layer 20 side, the second horizontal alignment film 340, the color filter layer 310, and the support substrate 300. The second substrate 30 preferably also has a plurality of columnar spacers (not shown). Note that the first substrate 10 may have a plurality of columnar spacers.

[0100] The supporting substrate 300 is preferably transparent and insulating, and examples of the supporting substrate 300 include a glass substrate and a plastic substrate.

[0101] The color filter layer 310 typically includes a red color filter provided in an area corresponding to a red pixel and transmitting red light, a green color filter provided in an area corresponding to a green pixel and transmitting green light, and a blue color filter provided in an area corresponding to a blue pixel and transmitting blue light. However, the number of types of color filters may be two or less, or four or more. If color display is not performed, the color filter layer 310 is omitted.

[0102] If necessary, an overcoat layer (also called a planarizing layer) may be provided to cover the color filter layer 310. Note that the white display may have a yellowish tinge depending on the material (e.g., transparent conductive material) forming the electrodes, the material forming the interlayer insulating layer and the dielectric layer, and the material forming the alignment film. In that case, the chromaticity of the white display may be adjusted (i.e., blue shift) by forming the overcoat layer from a blue resist, so that the chromaticity of the white display may be brought closer to that of a D65 light source, for example. The D65 light source is the CIE standard illuminant D65.

[0103] In the liquid crystal display device 1 of this embodiment, display is performed by a lateral electric field mode in which the liquid crystal layer 20 has a twisted orientation when no voltage is applied. This allows the cell gap to be increased, and the contrast fluctuation range with respect to the cell gap fluctuation to be reduced. Therefore, the occurrence of display unevenness is sufficiently suppressed, and the contrast of the reflective display becomes good. The twist angle θ1 of the liquid crystal layer 20 when no voltage is applied is preferably 58.3° or more and 89.9° or less. A more preferable range will be described later.

[0104] The twist angle θ1 of the liquid crystal layer 20 is the angle between the alignment direction of the liquid crystal molecules 21 determined by the first horizontal alignment film 140 and the alignment direction of the liquid crystal molecules 21 determined by the second horizontal alignment film 340. That is, it is the angle between the long axis direction of the liquid crystal molecules 21A (also referred to as the liquid crystal molecules 21A on the first substrate 10 side when no voltage is applied) near the first horizontal alignment film 140 and the long axis direction of the liquid crystal molecules 21B (also referred to as the liquid crystal molecules 21B on the second substrate 30 side when voltage is applied) near the second horizontal alignment film 340.

[0105] From the viewpoint of increasing the contrast ratio, the liquid crystal display device 1 is preferably in a normally black mode. The normally black mode is a display mode in which black is displayed when no voltage is applied and white is displayed when a voltage is applied.

[0106] The liquid crystal display device 1 is also configured with a plurality of components, such as the above-mentioned components, external circuits such as a TCP (tape carrier package) and a PCB (printed wiring board), optical films such as a viewing angle widening film and a brightness enhancing film, and a bezel (frame), and some of the components may be incorporated into other components. These are not particularly limited, and those commonly used in the field of liquid crystal display devices can be used, so their explanation will be omitted.

[0107] <Application Examples> The liquid crystal display device 1 of the present embodiment is suitable for various applications. In particular, it is preferably applicable to touch panels. Whether it is applied to an external touch panel or a built-in touch panel, it is useful because it can be produced at a lower cost than conventional touch panels and has an improved contrast ratio. In particular, it is preferably applicable to a built-in touch panel, and is particularly preferably applicable to an in-cell touch panel. In this way, by using the liquid crystal display device 1 of the present embodiment, it is possible to preferably realize an in-cell touch panel capable of displaying in a reflective mode, which has not been possible until now.

[0108] By realizing an in-cell touch panel capable of displaying in reflective mode, for example, a frame wiring area required for an external touch panel is not required, so that a narrow frame can be achieved, and since the touch panel function can be installed without a cover glass, it contributes to a thinner and lighter touch panel. In addition, since the touch function and the display function are driven in a time-division manner, the touch panel is not affected by LCD (liquid crystal display) noise, which can be the largest noise source in a touch panel. In other words, since no killer pattern occurs, tuning (adjustment) of the touch signal is easy. Furthermore, the loss of reflected light is sufficiently small, and a more natural and natural display can be obtained when writing with a pen. Moreover, compared to an external touch panel, a total cost reduction can be achieved from the user's perspective. Moreover, it is possible to combine finger input with pen input using the electromagnetic induction method (EMR), which allows for highly accurate pen writing.

[0109] An example in which the liquid crystal display device 1 is used in an in-cell touch panel will be further described. Fig. 7 is a plan view schematic illustrating the arrangement relationship between the touch sensor electrodes TX and the touch wirings TL included in the liquid crystal display device 1. As shown in Fig. 7, the liquid crystal display device 1 has a display area DR and a non-display area FR. The display area DR is defined by a plurality of pixels P (see Fig. 3, for example) arranged in a matrix. The non-display area FR is located on the periphery of the display area DR and is also referred to as a peripheral area or a frame area.

[0110] In the display region DR, the common electrode CE is divided into a plurality of segments TX. Each segment (common electrode portion) TX functions as a touch sensor electrode. In the example shown in FIG. 7, each touch sensor electrode TX is provided corresponding to two or more pixels P.

[0111] The liquid crystal display device 1 (more specifically, the first substrate 10) has a plurality of touch wirings TL. Each touch sensor electrode TX is electrically connected to a corresponding touch wiring TL. A connection portion TC between the touch sensor electrode TX and the touch wiring TL is also referred to as a touch wiring contact portion TC.

[0112] The touch wiring TL is connected to a touch driving unit TD provided in the non-display region FR. The touch driving unit TD is configured to switch, for example, between a display mode in which a plurality of touch sensor electrodes TX function as a common electrode CE and a touch detection mode in which the touch sensor electrodes TX function as the touch sensor electrodes TX in a time-division manner. For example, in the display mode, the touch driving unit TD applies a common signal to the touch sensor electrodes TX (common electrodes CE) via the touch wiring TL. On the other hand, in the touch detection mode, the touch driving unit TD applies a touch driving signal to the touch sensor electrodes TX via the touch wiring TL.

[0113] 7, the touch wirings TL extend in the column direction (the same direction as the source wirings SL). Some of the touch wirings TL extend to the corresponding touch sensor electrodes TX, crossing one or more other touch sensor electrodes TX.

[0114] Focusing on a certain touch sensor electrode TX, a first touch wiring TL1 that supplies a signal to the touch sensor electrode TX extends to a touch wiring contact portion TC, and a second touch wiring TL2 that supplies a signal to another touch sensor electrode TX extends across the touch sensor electrode TX. The second touch wiring TL2 and the touch sensor electrode TX overlap with each other via an insulating layer. Depending on the position of the touch sensor electrode TX, two or more touch wirings TL may be arranged to extend across the touch sensor electrode TX, or no touch wiring TL may be arranged to cross the touch sensor electrode TX.

[0115] In addition to the touch drive unit TD, the non-display area FR is provided with peripheral circuits including drive circuits such as a gate driver that supplies gate signals to the gate bus lines (gate wiring) GL and a source driver that supplies source signals to the source bus lines (source wiring) SL (not shown). These drive circuits may be mounted on the first substrate (TFT substrate) 10, for example, or may be formed integrally (monolithically). A semiconductor chip including some or all of the drive circuits may be mounted on the non-display area FR.

[0116] In an in-cell touch panel, it is particularly preferable to use an In-Ga-Zn-O based semiconductor as the TFT 110. From the viewpoint of achieving flickerless (also called flicker-free), it is particularly preferable to use a negative type liquid crystal material. This is for the following reason. In the in-plane electric field method of the FFS mode using a positive type liquid crystal material, flexoelectric polarization occurs spontaneously in the liquid crystal layer due to the influence of the fine slit electrodes on the electrodes when a voltage is applied (i.e., the fringe electric field). Since the liquid crystal responds according to this flexoelectric polarization, the luminance changes when the polarity is inverted, which is thought to be easily visually recognized as flicker.

[0117] (Modification 1 of the first embodiment) In the first embodiment, the first electrode 121, which is a lower layer electrode, is the common electrode CE, and the second electrode 122, which is an upper layer electrode, is the pixel electrode PE. However, the second electrode 122 may be the common electrode CE, and the first electrode 121 may be the pixel electrode PE. In this example, the second electrode 122 (upper layer electrode) is the common electrode CE, and the first electrode 121 (lower layer electrode) is the pixel electrode PE (see FIG. 8).

[0118] FIG. 8 is a schematic cross-sectional view showing the liquid crystal display device 1 of this example in more detail. In this example as well, from the viewpoint of facilitating the generation of a transverse electric field, it is preferable that at least the upper layer electrode (common electrode CE in this example) is a slit electrode. The lower layer electrode (pixel electrode PE in this example) may be a planar electrode, i.e., a so-called solid electrode, or may be a slit electrode. As described above, the liquid crystal display device 1 of this modified example is particularly suitable as a relatively high-definition liquid crystal display device, i.e., a liquid crystal display device in which the area of ​​the pixel P is relatively small.

[0119] (Modification 2 of the first embodiment) In the first embodiment, an FFS mode liquid crystal display device has been described, but an IPS mode liquid crystal display device may also be used (however, the liquid crystal layer 20 has a twisted orientation when no voltage is applied). This modification is an IPS mode liquid crystal display device. In this modification, the first electrode 121 and the second electrode 122 are provided in the same layer, and it is preferable that both the first electrode 121 and the second electrode 122 are slit electrodes.

[0120] (Embodiment 2) In this embodiment, the features unique to this embodiment will be mainly described, and the description of the contents overlapping with the above-mentioned embodiment 1 will be omitted. This embodiment is substantially the same as embodiment 1, except that the liquid crystal display device further includes a retardation layer 40 and a polarizing plate 50.

[0121] Fig. 9 is a schematic cross-sectional view of a liquid crystal display device 1 as an example of this embodiment, and Fig. 10 is a schematic cross-sectional view showing the liquid crystal display device 1 as an example of this embodiment in more detail. As shown in Fig. 9, the liquid crystal display device 1 includes, in order from the rear side, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a retardation layer 40, and a polarizing plate 50. In this embodiment, a TFT substrate is used as the first substrate 10.

[0122] <Retardation layer> The retardation layer 40 is located between the second substrate 30 and the polarizing plate 50, and preferably includes a λ / 4 plate 41 and a λ / 2 plate 42 (see FIGS. 9 and 10). The arrangement order of these is preferably such that the λ / 4 plate 41 and the λ / 2 plate 42 are located from the liquid crystal layer 20 (and second substrate 30) side (see FIGS. 9 and 10).

[0123] The λ / 4 plate means a retardation plate that imparts an in-plane phase difference of 1 / 4 wavelength to incident light of wavelength λ, and is also called a λ / 4 wave plate or QWP (Quarter-Wave Plate). Specifically, the λ / 4 plate 41 can convert linearly polarized light into circularly polarized light or circularly polarized light into linearly polarized light. For example, linearly polarized light incident on the λ / 4 plate 41 becomes circularly polarized light when it is output from the λ / 4 plate 41.

[0124] The λ / 2 plate means a retardation plate that imparts an in-plane phase difference of 1 / 2 wavelength to incident light of wavelength λ, and is also called a λ / 2 wave plate, a half wave plate, or an HWP (Half-Wave Plate). Specifically, the λ / 2 plate 42 can rotate the vibration direction of the incident light beam by approximately 90°. For example, the circularly polarized light incident on the λ / 2 plate 42 becomes circularly polarized light with the rotation direction reversed when it is output.

[0125] Specifically, it is preferable to use uniaxial A-plates as the λ / 4 plate 41 and the λ / 2 plate .

[0126] <Polarizing plate> The polarizing plate 50 is located closer to the observation surface than the retardation layer 40 (see Figs. 9 and 10). The polarizing plate 50 may be a circular polarizing plate or a linear polarizing plate. Here, the linear polarizing plate means a polarizing plate having a function of extracting polarized light (linearly polarized light) that vibrates only in a specific direction from unpolarized light (natural light), partially polarized light, or polarized light, and is distinguished from a circular polarizing plate. Among them, a linear polarizing plate is preferable.

[0127] The polarizing plate 50 may be either an absorptive polarizing plate or a reflective polarizing plate. An absorptive polarizing plate is a polarizing plate that has the function of absorbing light that vibrates in a specific direction and transmitting polarized light (linearly polarized light) that vibrates in a direction perpendicular thereto. A reflective polarizing plate is a polarizing plate that has the function of reflecting light that vibrates in a specific direction and transmitting polarized light (linearly polarized light) that vibrates in a direction perpendicular thereto. Among these, an absorptive polarizing plate is preferred. It is particularly suitable to use an absorptive linear polarizing plate.

[0128] Examples of the absorptive polarizing plate include a polarizing plate obtained by dyeing and adsorbing an anisotropic material such as an iodine complex (or dye) on a polyvinyl alcohol film and then stretching and aligning the film. In general, in order to ensure mechanical strength and resistance to moist heat, the polyvinyl alcohol film is used in practical use with a protective film such as a triacetyl cellulose film laminated on both sides. Examples of the reflective polarizing plate include a film in which multiple dielectric thin films are laminated, a film in which multiple thin films with different refractive index anisotropy are laminated, a nanowire grid polarizing plate, and a polarizing plate using selective reflection of a cholesteric liquid crystal.

[0129] When the slit angle is changed, the polarization axis direction 50AA of the polarizing plate 50, the slow axis direction 41SA of the λ / 4 plate 41, and the slow axis direction 42SA of the λ / 2 plate are changed in the same direction by the same angle.

[0130] <Preferred Settings> In the following, preferred settings such as the twist angle and retardation dΔn of the liquid crystal layer 20 and the axial settings of the optical films (i.e., the polarizing plate and the phase difference plate) in this embodiment will be further described for the cases where the liquid crystal material constituting the liquid crystal layer 20 is of the positive type and the negative type. Note that an absorptive polarizing plate is used as the polarizing plate 50.

[0131] (i) When the liquid crystal material is a positive type (i-1) Preferred Settings Fig. 11 shows an example of optical settings that are particularly preferable from the viewpoint of improving the contrast ratio. Fig. 11 is a plan view conceptually showing the relationship between the long axis direction of the liquid crystal molecules 21 in the liquid crystal layer 20 when no voltage is applied, the in-plane slow axis 41SA of the λ / 4 plate 41, the in-plane slow axis 42SA of the λ / 2 plate 42, and the polarization axis 50AA of the polarizer 50 in a liquid crystal display device 1 including, in order from the rear side, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a λ / 4 plate 41, a λ / 2 plate 42, and a polarizer 50. In Fig. 11, liquid crystal molecules 21A near the first horizontal alignment film 140 and liquid crystal molecules 21B near the second horizontal alignment film 340 are shown as the liquid crystal molecules 21.

[0132] In the following description, the angle when the reference orientation is 0° refers to the angle when Fig. 11 is likened to a clock face, the reference orientation, i.e., the direction perpendicular to the extension direction of the multiple strip-shaped portions SP, is the 0° direction (3 o'clock direction), and the twist direction is positive (counterclockwise). The twist direction means the direction twisted from the alignment orientation of the liquid crystal molecules 21A defined by the first horizontal alignment film 140 to the alignment orientation of the liquid crystal molecules 21B defined by the second horizontal alignment film 340 when the liquid crystal display device 1 is viewed from the observation surface side.

[0133] The twist angle θ1 of the liquid crystal layer 20 when no voltage is applied is preferably 58.3° or more and 89.9° or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, it is more preferably 64.0° or more and 88° or less, even more preferably 68.4° or more and 86° or less, and particularly preferably 71.4° or more and 84° or less.

[0134] With respect to a direction perpendicular to the extension direction of the strip portions SP as a reference (0°), the angle θ2 formed by the polarization axis 50AA of the polarizing plate 50 is preferably 5° or more and 35° or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, the angle is more preferably 15° or more and 34° or less, and even more preferably 20° or more and 33° or less.

[0135] With a direction perpendicular to the extension direction of the strip portions SP as a reference (0°), the angle θ3 formed by the in-plane slow axis 42SA of the λ / 2 plate 42 is preferably 25° or more and 50° or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, the angle is more preferably 35° or more and 49° or less, and even more preferably 40° or more and 48° or less.

[0136] With respect to the direction perpendicular to the extension direction of the strip portions SP as a reference (0°), the angle θ4 formed by the in-plane slow axis 41SA of the λ / 4 plate 41 is preferably 45° or more and 70° or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, the angle is more preferably 55° or more and 68° or less, and even more preferably 60° or more and 66° or less.

[0137] The retardation of the liquid crystal layer 20, i.e., the product (dΔn) of the thickness d of the liquid crystal layer 20 and the birefringence Δn of the liquid crystal material, is preferably 152.3 nm or more and 285.8 nm or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, it is more preferably 176.9 nm or more and 260.8 nm or less, even more preferably 195.8 nm or more and 250 nm or less, and particularly preferably 207.0 nm or more and 248 nm or less.

[0138] (ii) When the liquid crystal material is negative type (ii-1) Preferred Settings Fig. 12 shows an example of optical settings that are particularly preferable from the viewpoint of improving the contrast ratio. Fig. 12 is a plan view conceptually showing the relationship between the long axis direction of the liquid crystal molecules 21 in the liquid crystal layer 20 when no voltage is applied, the in-plane slow axis 41SA of the λ / 4 plate 41, the in-plane slow axis 42SA of the λ / 2 plate 42, and the polarization axis 50AA of the polarizer 50 in the liquid crystal display device 1 including, in order from the rear side, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a λ / 4 plate 41, a λ / 2 plate 42, and a polarizer 50. In Fig. 12, liquid crystal molecules 21A near the first horizontal alignment film 140 and liquid crystal molecules 21B near the second horizontal alignment film 340 are shown as the liquid crystal molecules 21.

[0139] In the following explanation, the angle when the reference orientation is 0° is the angle when Figure 12 is likened to a clock face, the reference orientation, i.e., the direction perpendicular to the extension direction of the multiple strip-shaped portions SP, is set to the 0° direction (3 o'clock direction), and the twist direction is positive (counterclockwise).

[0140] The twist angle θ1 of the liquid crystal layer 20 when no voltage is applied is preferably 58.3° or more and 89.9° or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, it is more preferably 64.0° or more and 88° or less, even more preferably 68.4° or more and 86° or less, and particularly preferably 71.4° or more and 84° or less.

[0141] With respect to a direction perpendicular to the extension direction of the strip portions SP as a reference (0°), the angle θ2 formed by the polarization axis 50AA of the polarizing plate 50 is preferably −85° or more and −55° or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, the angle is more preferably −75° or more and −56° or less, and even more preferably −70° or more and −57° or less.

[0142] With respect to the direction perpendicular to the extension direction of the strip portions SP as a reference (0°), the angle θ3 formed by the in-plane slow axis 42SA of the λ / 2 plate 42 is preferably −65° or more and −40° or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, the angle is more preferably −55° or more and −41° or less, and even more preferably −50° or more and −42° or less.

[0143] With respect to the direction perpendicular to the extension direction of the strip portions SP as a reference (0°), the angle θ4 formed by the in-plane slow axis 41SA of the λ / 4 plate 41 is preferably −40° or more and −15° or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, the angle is more preferably −30° or more and −20° or less, and even more preferably −27° or more and −24° or less.

[0144] The retardation of the liquid crystal layer 20, i.e., the product (dΔn) of the thickness d of the liquid crystal layer 20 and the birefringence Δn of the liquid crystal material, is preferably 151.2 nm or more and 285.1 nm or less. This improves the contrast ratio. From the viewpoint of further improving the contrast ratio, it is more preferably 175.9 nm or more and 250 nm or less, even more preferably 193.8 nm or more and 246 nm or less, and particularly preferably 204.7 nm or more and 245 nm or less.

[0145] (Modification 1 of the second embodiment) In the second embodiment, the first electrode 121, which is a lower layer electrode, is the common electrode CE, and the second electrode 122, which is an upper layer electrode, is the pixel electrode PE. However, the second electrode 122 may be the common electrode CE, and the first electrode 121 may be the pixel electrode PE. In this example, the second electrode 122 (upper layer electrode) is the common electrode CE, and the first electrode 121 (lower layer electrode) is the pixel electrode PE (see FIG. 13).

[0146] FIG. 13 is a schematic cross-sectional view showing the liquid crystal display device 1 of this example in more detail. In this example as well, from the viewpoint of easily generating a transverse electric field, it is preferable that at least the upper layer electrode (common electrode CE in this example) is a slit electrode. The lower layer electrode (pixel electrode PE in this example) may be a planar electrode, i.e., a so-called solid electrode, or may be a slit electrode. As described above, the liquid crystal display device 1 of this modified example is particularly suitable as a relatively high-definition liquid crystal display device, i.e., a liquid crystal display device in which the area of ​​the pixel P is relatively small.

[0147] (Embodiment 3) In this embodiment, features unique to this embodiment will be mainly described, and descriptions of contents overlapping with the above-mentioned embodiments 1 and 2 will be omitted. In the embodiments 1 and 2, a reflective liquid crystal display device has been described as an example, but in this embodiment, a semi-transmissive liquid crystal display device will be described. The liquid crystal display device of this embodiment differs from the liquid crystal display device of embodiment 2 mainly in that a light source is provided on the rear side of the liquid crystal layer 20.

[0148] FIG. 14 is a cross-sectional schematic diagram of a liquid crystal display device 1 as an example of this embodiment. The liquid crystal display device 1 further includes a light source 61 (also referred to as a backlight) on the rear side of the liquid crystal layer 20. In addition, it is preferable that the liquid crystal display device 1 further includes a polarizing plate 50' and a retardation layer 40'. More preferably, as shown in FIG. 14, the liquid crystal display device 1 includes, in order from the rear side, the light source 61, the polarizing plate 50', the retardation layer 40', the first substrate 10, the liquid crystal layer 20, the second substrate 30, the retardation layer 40, and the polarizing plate 50. In this embodiment, a TFT substrate is also suitable as the first substrate 10.

[0149] The light source 61 (backlight) is not particularly limited as long as it irradiates light, and may be a direct type, an edge type, or any other type. Specifically, for example, it is preferable that the light source has a light emitting diode (LED) or other such light source, a light guide plate, and a reflective sheet, and may further have a diffusion sheet or a prism sheet.

[0150] The polarizing plate 50' is disposed on the rear side of the liquid crystal layer 20. More specifically, it is disposed on the rear side of the first substrate 10. The polarizing plate 50' may be a circular polarizing plate or a linear polarizing plate, but is preferably a linear polarizing plate. Also, it may be an absorptive polarizing plate or a reflective polarizing plate, but is preferably an absorptive polarizing plate. In particular, it is preferable to use an absorptive linear polarizing plate.

[0151] The retardation layer 40' is disposed between the polarizing plate 50' and the liquid crystal layer 20. More specifically, it is disposed between the polarizing plate 50' and the first substrate 10. The retardation layer 40' may include, for example, a λ / 4 plate and a λ / 2 plate. The arrangement order of these is preferably, for example, the λ / 2 plate and the λ / 4 plate from the rear side.

[0152] In the liquid crystal display device 1 of this embodiment, each pixel P has a reflective region Rf for performing display in a reflective mode and a transmissive region Tr for performing display in a transmissive mode (see FIG. 15). FIG. 15 is a schematic plan view conceptually showing that each pixel P has a reflective region Rf and a transmissive region Tr in the liquid crystal display device 1 of this embodiment. A reflective layer 130 (see FIG. 2, for example) is arranged in the reflective region Rf, but the reflective layer 130 is not arranged in the transmissive region Tr. The proportion of the area of ​​the transmissive region Tr in each pixel P can be appropriately set depending on the application, etc., but is preferably, for example, 20% or more and 90% or less. The position and shape of the transmissive region Tr in the pixel P can also be appropriately set depending on the application, etc.

[0153] In the liquid crystal display device of this embodiment, i.e., the semi-transmissive liquid crystal display device, similarly to the reflective liquid crystal display device, the contrast ratio of the reflective display can be sufficiently improved by performing display in the lateral electric field mode in which the liquid crystal layer 20 has a twisted orientation when no voltage is applied. Therefore, the liquid crystal display device 1 of this embodiment is also useful as an in-cell touch panel capable of displaying in the reflective mode at low cost and with an improved contrast ratio.

[0154] (Embodiment 4) In this embodiment, features unique to this embodiment will be mainly described, and descriptions of contents overlapping with the above-mentioned embodiment 1 will be omitted. The liquid crystal display device of this embodiment mainly differs from the liquid crystal display device of embodiment 1 in that a light source is provided on the observation surface side of the liquid crystal layer 20. The liquid crystal display device of this embodiment is a reflective liquid crystal display device.

[0155] Fig. 16 is a cross-sectional schematic diagram of a liquid crystal display device 1 as one example of this embodiment. The liquid crystal display device 1 of this embodiment further includes a light source 62 (also referred to as a front light) on the observation surface side of the liquid crystal layer 20. More preferably, as shown in Fig. 16, the liquid crystal display device 1 includes, in this order from the rear side, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a retardation layer 40, a polarizing plate 50, and a light source 62. In this embodiment as well, a TFT substrate is suitable as the first substrate 10.

[0156] The light source 62 (front light) is not particularly limited as long as it can irradiate light. Specifically, for example, it is preferable that the light source has a light emitting diode (LED) or other light source and a light guide plate. By further including the light source 62, the reflective liquid crystal display device 1 can perform bright reflective display even in an environment where sufficient ambient light cannot be obtained.

[0157] Although the embodiments of the present invention have been described above, the individual matters described above can all be applied to the present invention as a whole.

[0158] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following, an absorptive polarizing plate is used as the polarizing plate 50.

[0159] (Verification example 1) Using a mobile TFT substrate (first substrate) 10, an FFS mode device capable of displaying in a reflective mode was fabricated (see FIG. 20A). Specifically, as shown in FIG. 17A, a pixel electrode PE and a common electrode CE for applying a voltage to the liquid crystal layer 20 were arranged on the TFT substrate 10 side, and the common electrode CE, which is an upper layer electrode (second electrode 122), was made into a slit electrode having a plurality of strip portions SP and a slit Sl located between two adjacent strip portions, as shown in FIG. 18. The width L of each strip portion SP was 1.6 μm, and the width of each slit Sl was 3.0 μm. The strip portions SP were linearly shaped extending substantially parallel to each other and in the same direction, but were bent halfway (see f in FIG. 18). The end f of the bend is also called a kink portion or a bent portion. A negative liquid crystal material was used for the liquid crystal layer 20. The pixel electrode PE, which is a lower layer electrode (first electrode 121), was made into a solid electrode. In addition, a black-and-white mode was used without disposing a color filter. Fig. 17A is a schematic cross-sectional view of the device fabricated in this example, and Fig. 18 is a CAD (Computer Aided Design) drawing showing only the pixel electrode PE and the common electrode CE on the TFT substrate side in a plan view.

[0160] First, this device is set to a white display state (i.e., 255 gradation display) as an initial state (see FIG. 20A). Next, when black characters are written on the device in this state, a black area is generated (see FIG. 20B). After that, the written characters are erased (i.e., the device is returned to the white display state) (see FIG. 20C). When this operation was performed (see FIGS. 20A to 20C), afterimages of the characters were visually recognized as burn-in (see the area surrounded by the dashed line in FIG. 20C). FIG. 20A is a planar photograph of the device in its initial state taken from the observation surface side, FIG. 20B is a planar photograph of the device in its initial state taken from the observation surface side after black characters have been written, and FIG. 20C is a planar photograph of the device in its initial state taken from the observation surface side after the written characters have been erased. When the part where the afterimage occurred was observed with a microscope (OLYMPUS "BX51"), it was confirmed that alignment disturbance occurred at the end f of each common electrode CE, also called a kink part (see FIG. 19). It is believed that the alignment disorder occurring at this kink portion f causes a difference in brightness (i.e., a difference in reflectance) between this portion and other portions (e.g., the center of the pixel), which causes the afterimage to be visible. Figure 19 is an image (planar image) of the inside of the device observed with a microscope. Figure 18 is a CAD diagram of the electrode structure of the portion shown in Figure 19.

[0161] The present inventors have further investigated the cause of this alignment disorder. The slit angle of the slit electrode (common electrode CE in this example) is different between the pixel center (near (a) in Figs. 18 and 19) and the pixel end (near (b) in Figs. 18 and 19). In the slit electrode of this example, the slit angle is -10 degrees in the pixel center (a), whereas it is -20 degrees in the pixel end (b). The present inventors have speculated that the difference in slit angle causes the liquid crystal molecules 21 to rotate in different directions when a voltage is applied (see Fig. 21). Fig. 21 is a plan view conceptually showing that the liquid crystal molecules 21 (negative liquid crystal) rotate in different directions between the pixel center (a) and the pixel end (b). The orientation of the liquid crystal molecules 21A on the TFT substrate 10 side when no voltage is applied (i.e., initial orientation) is represented by the direction of the liquid crystal molecules 21A, and the orientation of the liquid crystal molecules 21A on the TFT substrate 10 side when a voltage is applied is represented by the direction of the liquid crystal molecules 21A(A). The 3 o'clock direction is 0 degrees, the counterclockwise direction is positive (+), and the twist angle is +74 degrees. When a voltage is applied, the liquid crystal molecules 21A rotate clockwise (-) at the center of the pixel (see FIG. 21(a)), whereas they rotate counterclockwise (+) at the edge of the pixel (see FIG. 21(b)). The boundary between the center of the pixel and the edge of the pixel corresponds to the portion where the slit angle changes, and here the orientation of the liquid crystal molecules 21 becomes discontinuous. Therefore, the orientation is disturbed, and thus a luminance difference occurs between pixels where the orientation is not disturbed and pixels where the orientation is not disturbed, which is considered to be visually recognized as an afterimage.

[0162] For reference, Figures 22 and 23 are shown as diagrams conceptually illustrating that the rotation direction of liquid crystal molecules 21 (i.e., liquid crystal molecules 21A on the TFT substrate side) when a voltage is applied is different between the pixel center (a) and the pixel end (b). Figure 22 is a diagram in which a conceptual diagram showing the rotation direction of liquid crystal molecules 21 (i.e., Figure 21) is superimposed on Figure 18, and Figure 23 is a diagram in which a conceptual diagram showing the rotation direction of liquid crystal molecules 21 (i.e., Figure 21) is superimposed on Figure 19.

[0163] (Test Examples 1 and 2) Assuming a reflective liquid crystal display device 1 using a negative type liquid crystal material, the occurrence of alignment disturbances with and without a kink portion was compared by a three-dimensional optical simulation. Specifically, as shown in FIG. 17B, a pixel electrode PE and a common electrode CE for applying a voltage to the liquid crystal layer 20 are arranged on the TFT substrate (first substrate) 10 side, and the common electrode CE, which is an upper layer electrode (second electrode 122), is a slit electrode having a plurality of strip portions SP and a slit Sl located between two adjacent strip portions. The width L of each strip portion SP is 2.4 μm, and the width of each slit Sl is 2.2 μm. A negative type liquid crystal material is used for the liquid crystal layer 20. The pixel electrode PE, which is a lower layer electrode (first electrode 121), is a solid electrode. FIG. 17B is a schematic cross-sectional view of the device assumed in this example.

[0164] Here, in Test Example 1, the multiple strip-shaped portions SP constituting the slit electrode (common electrode CE) were linearly shaped and generally parallel to each other and extending in the same direction, but had bent portions f at their ends (see FIG. 24A (b)). In contrast, in Test Example 2, the multiple strip-shaped portions SP were linearly shaped and generally parallel to each other and extending in the same direction, but did not include bent portions f (see FIG. 24B (b)). FIG. 24A shows the simulation results of Test Example 1 (see (a)), and a conceptual diagram of multiple strip-shaped portions SP based on the results (see (b)). FIG. 24B shows the simulation results of Test Example 2 (see (a)), and a conceptual diagram of multiple strip-shaped portions SP based on the results (see (b)).

[0165] As a result of evaluating the reflectance distribution by three-dimensional optical simulation, the result of Test Example 1 is shown in (a) of FIG. 24A, and the result of Test Example 2 is shown in (a) of FIG. 24B. In Test Example 1, alignment disturbance occurs at a bent portion f called a kink portion, and the brightness of the kink portion f is low (see (a) of FIG. 24A). In contrast, in Test Example 2, alignment disturbance does not occur, and the brightness of the end portion of the common electrode CE (the portion corresponding to the kink portion f in Test Example 1) increases compared to Test Example 1 (see (a) of FIG. 24B). Therefore, it was confirmed that alignment disturbance does not occur by making the multiple strip portions SP constituting the slit electrode have a linear shape extending approximately parallel to each other and in the same direction and having a shape that does not include a bent portion. It is considered that alignment disturbance does not occur because the relationship between the alignment of the liquid crystal molecules 21 and the slit angle becomes uniform within each pixel.

[0166] (Test Examples 3 and 4) From the above, it is considered that the cause of the alignment disorder is the difference in slit angle of the slit electrode between the kink portion and the other portion. Therefore, the change in the reflection mode efficiency due to the slit angle was evaluated and analyzed by a three-dimensional optical simulation. Specifically, in a liquid crystal display device 1 having a configuration including a reflective liquid crystal panel 1X, a retardation layer 40, and a polarizing plate 50 in this order, a structure was assumed in which a λ / 4 plate 41 and a λ / 2 plate 42 are arranged as the retardation layer 40 in this order from the liquid crystal panel 1X side (see FIG. 9). A uniaxial retardation plate with a retardation of 110 nm is used as the λ / 4 plate 41, and a uniaxial retardation plate with a retardation of 260 nm is used as the λ / 2 plate 42.

[0167] The liquid crystal panel 1X has a pixel electrode PE and a common electrode CE arranged on the TFT substrate (first substrate) 10 side for applying a voltage to the liquid crystal layer 20, and the common electrode CE, which is an upper layer electrode (second electrode 122), is a slit electrode having a plurality of strip portions SP and a slit Sl located between two adjacent strip portions (see Figs. 25 and 26). The strip portions SP are linearly shaped extending substantially parallel to each other and in the same direction, and do not include any bent portions, and the slit angle is set to 0° (see Fig. 26). The pixel electrode PE, which is a lower layer electrode (first electrode 121), is a solid electrode. A liquid crystal layer with a monodomain structure (a liquid crystal layer that performs normally black display) is assumed. In Fig. 25, the film thickness of some layers is written in parentheses after the reference symbol representing the layer.

[0168] An example in which a positive-type liquid crystal material was used for the liquid crystal layer 20 was Test Example 3, and an example in which a negative-type liquid crystal material was used was Test Example 4. The ratio of the width L of each strip portion SP to the width S of each slit Sl (referred to as the L / S condition) was L / S (μm) = 2.2 / 4.1 in Test Examples 3-1 and 4-1, L / S (μm) = 1.6 / 3.0 in Test Examples 3-2 and 4-2, and L / S (μm) = 3.0 / 5.0 in Test Examples 3-3 and 4-3.

[0169] Fig. 25 is a schematic cross-sectional view of a liquid crystal panel 1X included in the device assumed in this example. Fig. 26 is a schematic conceptually illustrating the electrode structure of a pixel electrode PE and a common electrode CE, and particularly illustrates an example (Test Example 3-2 and Test Example 4-2) in which L / S (μm)=1.6 / 3.0. In Fig. 26, the orientation (i.e., initial orientation) of the liquid crystal molecules 21A on the TFT substrate 10 side when no voltage is applied is represented by the orientations of the positive-type liquid crystal molecules 21A(p) and the negative-type liquid crystal molecules 21A(n).

[0170] In the actual simulation, in order to simplify the condition setting, the pretwist angle of the liquid crystal molecules 21 and the axial angle of the optical film were changed instead of changing the slit angle. However, the twist angle θ1 was fixed (74° in Test Examples 3 and 4). Specifically, the pretwist angle of the liquid crystal molecules 21 and the axial angle of each optical film were rotated by the same angle as the slit angle, based on the axial setting of the optical film described below. The optical film means the polarizing plate 50 and the retardation layer 40 (λ / 4 plate 41 and λ / 2 plate 42 in this example). The pretwist angle of the liquid crystal molecules 21 is the initial orientation angle of the liquid crystal molecules 21A on the TFT substrate (first substrate) 10 side with respect to a reference (in this specification, the 3 o'clock direction when the liquid crystal panel is viewed in plan from the observation surface side is set as the reference 0°).

[0171] The axis setting of each optical film and the retardation dΔn of the liquid crystal layer 20 were as shown in FIG. 27 and Table 1 in Test Example 3 (positive liquid crystal), and as shown in FIG. 28 and Table 1 in Test Example 4 (negative liquid crystal). FIG. 27 is a plan view conceptually showing the axis setting of each optical film used in Test Example 3, and FIG. 28 is a plan view conceptually showing the axis setting of each optical film used in Test Example 4. In FIG. 27 and FIG. 28, each optical film is likened to a clock face, with the 3 o'clock direction being 0° and the counterclockwise direction being positive. The axis angle of each optical film is the angle when observed in plan view from the observation surface side.

[0172] The voltage was set in increments of 0.5 V from 0 V to 6 V. The average reflective mode efficiency of the luminance distribution was calculated, and the reflective mode efficiency when 5 V was applied was plotted for each L / S condition. Here, the reflection mode efficiency is given by the following formula: Reflective mode efficiency (%) = (Luminance with polarizer) / (Luminance without polarizer) x 100 The results are shown in Figures 29 and 30. Figure 29 is a graph showing the results of Test Example 3 (positive type, twist angle 74°), and Figure 30 is a graph showing the results of Test Example 4 (negative type, twist angle 74°).

[0173] [Table 1]

[0174] In FIG. 29 (positive type, twist angle 74°), it is confirmed that the reflectance changes significantly at a certain slit angle. This is considered to be due to the difference in the rotation direction of the liquid crystal molecules when a voltage is applied. It is also confirmed that the slit angle at which the reflectance becomes discontinuous changes depending on the L / S condition. The slit angle at which the reflectance becomes discontinuous is around -11.5° in Test Example 3-1 (L / S (μm) = 2.2 / 4.1), around -9.5° in Test Example 3-2 (L / S (μm) = 1.6 / 3.0), and around -13° in Test Example 3-3 (L / S (μm) = 3.0 / 5.0). Therefore, in each L / S condition, the slit angle when the reflective mode efficiency is 30% or more, the slit angle when the reflective mode efficiency is 33% or more, and the slit angle when the reflective mode efficiency is 36% or more are set to the above-mentioned preferred range, more preferred range, and even more preferred range, respectively.

[0175] Similarly, in FIG. 30 (negative type, twist angle 74°), it is confirmed that the reflectance changes significantly at a certain slit angle, and that the slit angle at which the reflectance becomes discontinuous changes depending on the L / S condition. The slit angle at which the reflectance becomes discontinuous is around -19° in Test Example 4-1 (L / S (μm) = 2.2 / 4.1), around -15° in Test Example 4-2 (L / S (μm) = 1.6 / 3.0), and around -22° in Test Example 4-3 (L / S (μm) = 3.0 / 5.0). Therefore, the slit angle at which the reflection mode efficiency is 30% or more and the slit angle at which the reflection mode efficiency is 33% or more under each L / S condition are set to the above-mentioned preferred range and more preferred range, respectively.

[0176] (Test Examples 5 and 6) Test Example 5 is an example in which the conditions were substantially the same as those of Test Example 3, except that the twist angle θ1 was 83°, and the axial settings of each optical film and the retardation dΔn of the liquid crystal layer 20 were as shown in FIG. 31 and Table 2. Test Example 6 is an example in which the conditions were substantially the same as those of Test Example 4, except that the twist angle θ1 was 83°, and the axial settings of each optical film and the retardation dΔn of the liquid crystal layer 20 were as shown in FIG. 32 and Table 2. The L / S conditions were L / S (μm) = 2.2 / 4.1 in Test Examples 5-1 and 6-1, L / S (μm) = 1.6 / 3.0 in Test Examples 5-2 and 6-2, and L / S (μm) = 3.0 / 5.0 in Test Examples 5-3 and 6-3. FIG. 31 is a plan view conceptually showing the axial settings of the optical films used in Test Example 5, and FIG. 32 is a plan view conceptually showing the axial settings of the optical films used in Test Example 6.

[0177] The voltage was set in 0.5 V increments from 0 V to 6 V. The average reflective mode efficiency of the luminance distribution was determined, and the reflective mode efficiency at an applied voltage of 5 V was plotted for each L / S condition. The results are shown in Fig. 33 and Fig. 34. Fig. 33 is a graph showing the results of Test Example 5 (positive type, twist angle 83°), and Fig. 34 is a graph showing the results of Test Example 6 (negative type, twist angle 83°).

[0178] [Table 2]

[0179] FIG. 33 (positive type, twist angle 83°) also confirms that the reflectance changes significantly at a certain slit angle, and that the slit angle at which the reflectance becomes discontinuous changes depending on the L / S condition. The slit angle at which the reflectance becomes discontinuous is around -11.5° in Test Example 5-1 (L / S (μm) = 2.2 / 4.1), around -9.5° in Test Example 5-2 (L / S (μm) = 1.6 / 3.0), and around -13° in Test Example 5-3 (L / S (μm) = 3.0 / 5.0). Therefore, in each L / S condition, the slit angle when the reflection mode efficiency is 30% or more, the slit angle when the reflection mode efficiency is 33% or more, and the slit angle when the reflection mode efficiency is 36% or more are set to the above-mentioned preferred range, more preferred range, and even more preferred range, respectively.

[0180] Similarly, in FIG. 34 (negative type, twist angle 83°), it is confirmed that the reflectance changes significantly at a certain slit angle, and that the slit angle at which the reflectance becomes discontinuous changes depending on the L / S condition. The slit angle at which the reflectance becomes discontinuous is around -19° in Test Example 6-1 (L / S (μm) = 2.2 / 4.1), around -15° in Test Example 6-2 (L / S (μm) = 1.6 / 3.0), and around -22° in Test Example 6-3 (L / S (μm) = 3.0 / 5.0). Therefore, in each L / S condition, the slit angle when the reflection mode efficiency is 30% or more, the slit angle when the reflection mode efficiency is 33% or more, and the slit angle when the reflection mode efficiency is 36% or more are set to the above-mentioned preferred range, more preferred range, and even more preferred range, respectively.

[0181] The above-described aspects of the present invention may be combined as appropriate without departing from the gist of the present invention. [Explanation of symbols]

[0182] 1:LCD display device 1X: LCD panel 10, 30: PCB 20: Liquid crystal layer 21, 21A, 21B: Liquid crystal molecules 40, 40': Retardation layer 41:λ / 4 plate 42:λ / 2 plate 41SA, 42SA: In-plane slow axis 50, 50': Polarizing plate 50AA: Polarization axis 61, 62: Light source 100, 300: Support substrate 110: TFT 121, 122: Electrode 130: Reflective layer 140, 340: Horizontal alignment film 150G: Gate insulating film 151, 152: Interlayer insulating layer 153: Dielectric layer 160: Contact electrode 310: Color filter layer BP: Backplane circuit CE: Common electrode PE: Pixel electrode CH1, CH2: Contact hole DR:Display area FR: Hidden area GL: Gate wiring SL: Source wiring f: Kink (bending part) p: protruding part P: Pixel Rf:Reflection area Tr:Transmission area Sl: Slit SP: Belt TC: Touch wiring contact part TD: Touch drive unit TL, TL1, TL2: Touch wiring TX: Touch sensor electrode

Claims

1. A first substrate; a second substrate facing the first substrate; a liquid crystal layer provided between the first substrate and the second substrate; A liquid crystal display device having a plurality of pixels arranged in a matrix, the first substrate has a reflective layer that reflects light, a first electrode and a second electrode that can generate a transverse electric field in the liquid crystal layer, and a first horizontal alignment film that is in contact with the liquid crystal layer; At least one of the first electrode and the second electrode has a plurality of strip portions and a slit located between two adjacent strip portions of the plurality of strip portions, In each pixel, the plurality of strip-shaped portions are linearly shaped and extend substantially parallel to one another in the same direction, and do not include any bent portions; the second substrate has a second horizontal alignment film in contact with the liquid crystal layer, The liquid crystal layer has a twisted alignment when no voltage is applied. A liquid crystal display device characterized by the above-mentioned.

2. The plurality of band-shaped portions do not include a notch portion.

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

3. The extending direction of the plurality of strip-shaped portions is the same at least in adjacent pixels or in the display region.

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

4. The liquid crystal layer includes a positive type liquid crystal material.

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

5. The liquid crystal layer includes a negative type liquid crystal material.

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

6. The twist angle of the liquid crystal layer when no voltage is applied is 58.3° or more and 89.9° or less.

6. The liquid crystal display device according to claim 4, wherein the first and second electrodes are arranged in a first direction.

7. Single domain orientation 2. The liquid crystal display device according to claim 1 .

8. The alignment direction of the liquid crystal molecules on the first substrate side when no voltage is applied is in the range of −30° to 30° with respect to the direction in which the strip portions extend (0°).

6. The liquid crystal display device according to claim 4, wherein the first and second electrodes are arranged in a first direction.

9. The plurality of band-shaped portions have a ratio L / S of a width L per band-shaped portion in a plan view to a width S per slit in a plan view of 0.4 to 0.7 / 1.

6. The liquid crystal display device according to claim 4, wherein the first and second electrodes are arranged in a first direction.

10. Furthermore, a polarizing plate disposed on the outer side of the first substrate and / or the second substrate; a retardation layer disposed between the substrate and the polarizing plate; Equipped 2. The liquid crystal display device according to claim 1 .

11. the liquid crystal layer includes a positive type liquid crystal material; The polarizing plate is an absorptive polarizing plate, The light absorption axis of the polarizing plate is inclined from 5° to 35° with respect to a direction perpendicular to the extending direction of the plurality of strip-shaped portions as a reference (0°).

11. The liquid crystal display device according to claim 10.

12. the liquid crystal layer includes a positive type liquid crystal material; The retardation layer includes a λ / 2 plate, The in-plane slow axis of the λ / 2 plate is inclined from 25° to 50° with respect to a direction perpendicular to the direction in which the plurality of strip portions extend (0°).

11. The liquid crystal display device according to claim 10.

13. the liquid crystal layer includes a positive type liquid crystal material; The retardation layer includes a λ / 4 plate, The in-plane slow axis of the λ / 4 plate is inclined from 45° to 70° with respect to a direction perpendicular to the direction in which the plurality of strip portions extend (0°).

11. The liquid crystal display device according to claim 10.

14. the liquid crystal layer includes a negative type liquid crystal material; The polarizing plate is an absorptive polarizing plate, The absorption axis of the polarizing plate is −85° or more and −55° or less with respect to a direction perpendicular to the direction in which the plurality of strip-shaped portions extend as a reference (0°).

11. The liquid crystal display device according to claim 10.

15. the liquid crystal layer includes a negative type liquid crystal material; The retardation layer includes a λ / 2 plate, The in-plane slow axis of the λ / 2 plate is −65° or more and −40° or less with respect to a direction perpendicular to the direction in which the plurality of strip-shaped portions extend as a reference (0°).

11. The liquid crystal display device according to claim 10.

16. the liquid crystal layer includes a negative type liquid crystal material; The retardation layer includes a λ / 4 plate, The in-plane slow axis of the λ / 4 plate is −40° or more and −15° or less with respect to a direction perpendicular to the direction in which the plurality of strip-shaped portions extend as a reference (0°).

11. The liquid crystal display device according to claim 10.

17. Display in normally black mode 2. The liquid crystal display device according to claim 1 .

18. One of the first electrode and the second electrode is a pixel electrode provided in each of the plurality of pixels, and the other is a common electrode including a plurality of segments each capable of functioning as a touch sensor electrode; The first substrate has a plurality of touch wirings each connected to a corresponding one of the touch sensor electrodes.

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

19. Further, a light source is provided.

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

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