Semi-transmissive liquid crystal display device

Abstract

Provided is a semi-transmissive liquid crystal display device which is low-cost, has excellent field angle characteristics, and is useful as an in-cell touch panel. A semi-transmissive liquid crystal display device is provided with a first polarizing plate, a first phase difference layer, a first substrate, a liquid crystal layer, a second substrate, a second phase difference layer, and a second polarizing plate, the first substrate having a reflective layer, a pair of electrodes capable of generating a lateral electric field on the liquid crystal layer, and a first horizontal alignment film, and the second substrate having a second horizontal alignment film. The first phase difference layer includes a first lambda / 2 plate and a first lambda / 4 plate, the second phase difference layer includes a second lambda / 2 plate and a second lambda / 4 plate, at least one of the first phase difference layer and the second phase difference layer further includes a positive C plate, and the liquid crystal layer includes a liquid crystal material having negative dielectric anisotropy and is twisted when a voltage is not applied. Each of the pixels has: a reflective region that reflects light through the reflective layer and displays the light; and a transmissive region for transmitting and displaying the light.

Description

Technical Field

[0001] The following disclosure relates to a semi-transmissive liquid crystal display device. Background Art

[0002] Liquid crystal display devices are display devices that use liquid crystal materials for display. According to the display mode, they are generally divided into transmissive liquid crystal display devices and reflective liquid crystal display devices. Transmissive liquid crystal display devices are devices that display in a transmissive mode using transmitted light generated by the backlight source on the back of the screen, and reflective liquid crystal display devices are devices that display in a reflective mode using external light (also called ambient light) instead of backlight. As a display device having both of these characteristics, semi-transmissive liquid crystal display devices are also proposed, which have an area for displaying in a transmissive mode and an area for displaying in a reflective mode in each pixel.

[0003] Liquid crystal display devices can also be roughly divided according to the driving method of the liquid crystal. For example, it is known that there are a longitudinal electric field method in which the liquid crystal layer is driven by an electric field in a direction substantially perpendicular to the substrate surface to display, and a transverse electric field method in which the liquid crystal layer is driven by an electric field in a direction substantially parallel to the substrate surface to display. As examples of the longitudinal electric field method, TN (Twisted Nematic) mode and MVA (Multi-domain Vertical Alignment) mode are exemplified, and as examples of the transverse electric field method, IPS (In-plane Switching) mode and FFS (Fringe Field Switching) mode are exemplified. Patent documents 1 to 3 disclose semi-transmissive liquid crystal display devices of the transverse electric field method. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2006-126551 Patent Document 2: Japanese Patent Application Publication No. 2005-338256 Patent Document 3: Japanese Patent Application Publication No. 2005-338264 Summary of the invention Technical Problems to be Solved by the Invention

[0005] However, in recent years, liquid crystal display devices used in smartphones, tablet computers, etc. are generally given touch sensor functions. As touch sensor methods, various methods such as resistive film type, electrostatic capacitance type, and optical type are known. Liquid crystal display devices (also called touch panels) equipped with touch sensors have external touch sensor methods (external type) and built-in touch sensor methods (built-in type). The built-in touch panel has a narrower frame than the external touch panel, which is advantageous in thinness and lightness, and also has the advantage of increasing the transmittance of light.

[0006] There are two types of built-in touch panels: on-cell and in-cell. A cell refers to a display panel (also called a liquid crystal panel) having an active matrix substrate represented by a thin film transistor (TFT) substrate, an opposing substrate arranged opposite to the substrate, and a liquid crystal layer sandwiched between these substrates. However, in the in-cell type, a layer that performs the touch sensor function is usually arranged in the display panel, and 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 viewing side of the display panel. Among them, the in-cell type can realize the lightest and thinnest touch panel in principle.

[0007] Therefore, the inventors have studied liquid crystal display devices that can be used as in-cell touch panels and found that in a high-illuminance environment (i.e., a bright environment) such as outdoors under direct sunlight, although the brightness of a transmissive liquid crystal display device is insufficient and visibility is poor, the visibility of a reflective liquid crystal display device is good (see Fig.36A ), and in addition, in low-illuminance environments (i.e., dark environments) such as indoors and at night, reflective liquid crystal display devices are darker than transmissive liquid crystal display devices, and visibility is poor (refer to Fig.36B ). Fig.36A These are observation photographs of images displayed on the transmissive liquid crystal display device 1T and the reflective liquid crystal display device 1R outdoors under direct sunlight (illuminance of about 70,000 lx). It can be seen that the visibility is poor in the transmissive liquid crystal display device 1T, while the visibility is good in the reflective liquid crystal display device 1R. Fig.36B These are observation photographs when images are displayed on the transmissive liquid crystal display device 1T and the reflective liquid crystal display device 1R, respectively, in a room (illuminance is about 1000 lx). These are observation photographs when images are displayed on the transmissive liquid crystal display device 1T and the reflective liquid crystal display device 1R, respectively. It can be seen that the visibility is good in the transmissive liquid crystal display device 1T, and the visibility is poor in the reflective liquid crystal display device 1R.

[0008] On the other hand, it is also noted that an in-cell touch panel capable of displaying in a reflective mode has not yet been realized. The reason is believed to be that in the current reflective liquid crystal display device, one of a pair of electrodes for applying a voltage to the liquid crystal layer (also called an opposing electrode or a common electrode) is arranged on the opposing substrate side.

[0009] Therefore, in order to ensure good visibility in all environments, attention has been paid to semi-transmissive liquid crystal display devices, among which semi-transmissive liquid crystal display devices of the lateral electric field mode in which a pair of electrodes are both provided only on one side of the substrate have been carefully studied. However, in existing devices (for example, see patent documents 1 to 3), there are problems in the viewing angle characteristics in particular. In addition, the use of special optical films and the like to form the device has also been studied, but in this case, low cost cannot be achieved.

[0010] The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a semi-transmissive liquid crystal display device which is low-cost, has excellent viewing angle characteristics, and is also useful as an in-cell touch panel. Solutions to the problem

[0011] (1) One embodiment of the present invention is a semi-transmissive liquid crystal display device, which is a liquid crystal display device having a plurality of pixels, wherein the liquid crystal display device comprises, in order from the back side to the observation side, a first polarizing plate, a first retardation layer, a first substrate, a liquid crystal layer, a second substrate, a second retardation layer, and a second polarizing plate, wherein the first substrate comprises a reflective layer, a pair of electrodes 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, the second substrate comprises a second horizontal alignment film in contact with the liquid crystal layer, the first retardation layer comprises a first λ / 2 plate and a first λ / 4 plate, the second retardation layer comprises a second λ / 2 plate and a second λ / 4 plate, at least one of the first retardation layer and the second retardation layer further comprises a positive C plate, the liquid crystal layer comprises a liquid crystal material having a negative dielectric anisotropy and being twisted in orientation when no voltage is applied, and each pixel comprises: a reflective region for displaying by reflecting light through the reflective layer; and a transmissive region for displaying by transmitting light.

[0012] (2) In addition, one embodiment of the present invention is a semi-transmissive liquid crystal display device that satisfies any one of the following (i) to (iii) in addition to the structure of (1) above. (i) The second retardation layer includes one positive C plate, and the first retardation layer does not include a positive C plate. (ii) The second retardation layer includes one positive C plate, and the first retardation layer includes two positive C plates. (iii) The first retardation layer and the second retardation layer each include two positive C plates.

[0013] (3) In addition, a certain embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of the above-mentioned (1) or (2), has the above-mentioned first λ / 2 plate and the above-mentioned first λ / 4 plate in sequence from the back side, and the above-mentioned second λ / 2 plate and the above-mentioned second λ / 4 plate in sequence from the observation side, the in-plane phase difference Re of the above-mentioned first λ / 2 plate is substantially the same as that of the above-mentioned second λ / 2 plate, and the in-plane phase difference Re of the above-mentioned first λ / 4 plate is substantially the same as that of the above-mentioned second λ / 4 plate.

[0014] (4) In addition, an embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of the above-mentioned (1), the above-mentioned (2) or the above-mentioned (3), the above-mentioned positive C plate is located between the above-mentioned first λ / 2 plate and the above-mentioned first λ / 4 plate and / or between the above-mentioned second λ / 2 plate and the above-mentioned second λ / 4 plate.

[0015] (5) In addition, a certain embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of the above-mentioned (1), (2), (3) or (4), has an absolute value of the thickness direction phase difference Rth (nm) of the above-mentioned positive C plate of 150 to 270nm.

[0016] (6) In addition, a certain embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of the above-mentioned (1), the above-mentioned (2), the above-mentioned (3), the above-mentioned (4) or the above-mentioned (5), the above-mentioned phase difference layer also includes a second positive C plate, and the above-mentioned second positive C plate is located between the above-mentioned first λ / 2 plate and the above-mentioned first polarizing plate and between the above-mentioned second λ / 2 plate and the above-mentioned second polarizing plate.

[0017] (7) In addition, an embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of the above (6), has an absolute value of the thickness direction phase difference Rth (nm) of the above second positive C plate of 50 to 130 nm.

[0018] (8) In addition, an embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of above-mentioned (1), above-mentioned (2), above-mentioned (3), above-mentioned (4), above-mentioned (5), above-mentioned (6) or above-mentioned (7), has a twist angle of the above-mentioned liquid crystal layer being greater than 70 degrees and less than 85 degrees when no voltage is applied.

[0019] (9) In addition, an embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of above-mentioned (1), above-mentioned (2), above-mentioned (3), above-mentioned (4), above-mentioned (5), above-mentioned (6), above-mentioned (7) or above-mentioned (8), has a product (dΔn) of the thickness d of the above-mentioned liquid crystal layer and the birefringence Δn of the liquid crystal material which comprises the above-mentioned liquid crystal layer, which is greater than 218nm and less than 255nm.

[0020] (10) In addition, a certain embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of the above-mentioned (1), the above-mentioned (2), the above-mentioned (3), the above-mentioned (4), the above-mentioned (5), the above-mentioned (6), the above-mentioned (7), the above-mentioned (8) or the above-mentioned (9), takes the orientation direction of the liquid crystal molecules specified by the above-mentioned first horizontal orientation film as a reference (0°), and when the twisting direction is a positive angle, the polarization axis of the above-mentioned first polarizing plate, the in-plane slow axis of the above-mentioned first λ / 2 plate and the in-plane slow axis of the above-mentioned first λ / 4 plate are located at angles of 33.6° to 40.2°, 48.8° to 52.1° and -74.8° to -68.2°, respectively.

[0021] (11) In addition, a certain embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of the above-mentioned (1), the above-mentioned (2), the above-mentioned (3), the above-mentioned (4), the above-mentioned (5), the above-mentioned (6), the above-mentioned (7), the above-mentioned (8), the above-mentioned (9) or the above-mentioned (10), takes the orientation direction of the liquid crystal molecules specified by the above-mentioned first horizontal orientation film as a reference (0°), and when the twisting direction is a positive angle, the polarization axis of the above-mentioned second polarizing plate, the in-plane slow axis of the above-mentioned second λ / 2 plate and the in-plane slow axis of the above-mentioned second λ / 4 plate are located at angles of -69.5° to -64.0°, -51.5° to -47.5° and -26.9° to -22.9°, respectively.

[0022] (12) In addition, an embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10) or (11), at least one of the pair of electrodes has a plurality of strip-shaped portions and a slit located between two adjacent strip-shaped portions among the plurality of strip-shaped portions.

[0023] (13) In addition, a certain embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of the above-mentioned (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11) or (12), has an orientation direction of the liquid crystal molecules specified by the above-mentioned first horizontal orientation film, which is greater than -30° and less than 30° with the direction in which the above-mentioned multiple strip-shaped portions extend as a reference (0°).

[0024] (14) In addition, a certain embodiment of the present invention is a semi-transmissive liquid crystal display device, which is a single-domain oriented device based on the structure of the above (1), the above (2), the above (3), the above (4), the above (5), the above (6), the above (7), the above (8), the above (9), the above (10), the above (11), the above (12) or the above (13).

[0025] (15) In addition, an embodiment of the present invention is a semi-transmissive liquid crystal display device, which displays in a normally black mode based on the structure of the above (1), the above (2), the above (3), the above (4), the above (5), the above (6), the above (7), the above (8), the above (9), the above (10), the above (11), the above (12), the above (13) or the above (14).

[0026] (16) In addition, a certain embodiment of the present invention is a semi-transmissive liquid crystal display device, which, based on the structure of the above-mentioned (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14) or (15), one of the above-mentioned pair of electrodes is a pixel electrode respectively arranged in the above-mentioned multiple pixels, and the other is a common electrode including multiple segments that can function as touch sensor electrodes respectively, and the above-mentioned first substrate has multiple touch wirings respectively connected to the corresponding above-mentioned touch sensor electrodes.

[0027] (17) In addition, a certain embodiment of the present invention is a semi-transmissive liquid crystal display device, which, in addition to the structure of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15) or (16), also has a light source. Effects of the Invention

[0028] According to the present invention, it is possible to provide a semi-transmissive liquid crystal display device which is low-cost, has excellent viewing angle characteristics, and is useful as an in-cell touch panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic cross-sectional view of the liquid crystal display device 1 . Figure 2 1 is a schematic cross-sectional view showing the liquid crystal display device 1 in more detail. Figure 3 This is a schematic plan view of the entire liquid crystal display device 1 as viewed from the observation surface side. Figure 4 1 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 . Figure 5 This is a diagram for explaining the slit angle of negative liquid crystal molecules. Figure 6 It is a plan view schematically showing a specific example of a pixel. Fig. 7A It is a plan view schematically showing a specific example of a pixel. Figure 7B It is a plan view schematically showing a specific example of a pixel. Figure 7C It is a plan view schematically showing a specific example of a pixel. Fig.7D It is a plan view schematically showing a specific example of a pixel. Fig. 7E It is a plan view schematically showing a specific example of a pixel. Figure 7F It is a plan view schematically showing a specific example of a pixel. Figure 8 This is a plan view conceptually showing the relationship between the long axis direction of liquid crystal molecules 21A in the liquid crystal layer 20 and the optical axes of the optical films when no voltage is applied in the liquid crystal display device 1 . Fig. 9 It is a diagram for explaining the optical axis angle of the optical film. Fig.10 This is a diagram conceptually showing the setting of the optical axis. Fig.11 is a graph showing black transmissive mode efficiency. Fig. 12A is a graph showing black transmissive mode efficiency. Fig. 12B is a graph showing black transmissive mode efficiency. Fig. 12Cis a graph showing black transmissive mode efficiency. Fig.13 1 is a schematic plan view illustrating the arrangement relationship between the touch sensor electrodes TX and the touch wirings TL included in the liquid crystal display device 1 . Fig.14 1 is a schematic cross-sectional view showing the liquid crystal display device 1 in more detail. Fig.15 is a schematic cross-sectional view of the liquid crystal display device 1 . Fig.16 is a schematic cross-sectional view of the liquid crystal display device 1 . Fig.17 is a schematic cross-sectional view of the liquid crystal display device 1 . Fig.18A 1 is a schematic plan view showing the structure of the liquid crystal cell 1100 when viewed from the front. Fig.18B So Fig.18A The AA line in the figure is used as a cross-sectional schematic diagram of the cutting plane (AA line cross-sectional view). Fig.19A is a schematic cross-sectional view of the test unit 1000 . Fig.19B is a schematic cross-sectional view of the test unit 2000 . Fig.19C is a schematic cross-sectional view of the test unit 3000 . Fig.19D is a schematic cross-sectional view of the test unit 4000 . Fig.19E is a schematic cross-sectional view of the test unit 5000 . Fig.19F is a schematic cross-sectional view of the test unit 6000 . Figure 19G is a schematic cross-sectional view of the test unit 7000 . Fig.19H is a schematic cross-sectional view of the test unit 8000 . Fig.19I is a schematic cross-sectional view of the test unit 9000 . Fig. 20 2 is a diagram showing the results of Verification Example 1. Fig.21 2 is a diagram showing the results of Verification Example 1. Fig. 22 2 is a diagram showing the results of Verification Example 1. Fig.23 2 is a diagram showing the results of Verification Example 1. Fig.24 This is a diagram conceptually showing the setting of the optical axis. Fig.25 This is a diagram conceptually showing the setting of the optical axis. Fig.26 This is a diagram conceptually showing the setting of the optical axis. Fig.27A 2 is a diagram showing the results of Verification Example 3. Fig.27B 2 is a diagram showing the results of Verification Example 3. Fig.27C 2 is a diagram showing the results of Verification Example 3. Fig.28A 2 is a diagram showing the results of Verification Example 3. Fig.28B 2 is a diagram showing the results of Verification Example 3. Fig.28C 2 is a diagram showing the results of Verification Example 3. Fig.29A 2 is a diagram showing the results of Verification Example 3. Fig.29B 2 is a diagram showing the results of Verification Example 3. Fig.29C 2 is a diagram showing the results of Verification Example 3. Fig. 30A 2 is a diagram showing the results of Verification Example 3. Fig. 30B 2 is a diagram showing the results of Verification Example 3. Fig. 30C 2 is a diagram showing the results of Verification Example 3. Fig.31 It is the original image in normal view. Fig.32A 2 is a diagram showing the results of Verification Example 3. Fig.32B 2 is a diagram showing the results of Verification Example 3. Fig.32C 2 is a diagram showing the results of Verification Example 3. Fig.32D 2 is a diagram showing the results of Verification Example 3. Fig.33A 2 is a diagram showing the results of Verification Example 3. Fig.33B 2 is a diagram showing the results of Verification Example 3. Fig.33C 2 is a diagram showing the results of Verification Example 3. Fig.33D 2 is a diagram showing the results of Verification Example 3. Fig.34A 2 is a diagram showing the results of Verification Example 3. Fig.34B 2 is a diagram showing the results of Verification Example 3. Fig.34C 2 is a diagram showing the results of Verification Example 3. Fig.34D 2 is a diagram showing the results of Verification Example 3. Fig.35A 2 is a diagram showing the results of Verification Example 3. Fig.35B 2 is a diagram showing the results of Verification Example 3. Fig.35C 2 is a diagram showing the results of Verification Example 3. Fig.35D 2 is a diagram showing the results of Verification Example 3. Fig.36A These are observation photographs when images are displayed on the transmissive liquid crystal display device 1T and the reflective liquid crystal display device 1R outdoors under direct sunlight. Fig.36B These are observation photographs when images are displayed on the transmissive liquid crystal display device 1T and the reflective liquid crystal display device 1R in a room. DETAILED DESCRIPTION

[0030] (Definition of terms) In this specification, the observation side refers to the side closer to the screen (display surface) of the liquid crystal display device, and the rear side refers to the side farther from the screen (display surface) of the liquid crystal display device.

[0031] The voltage non-applied state refers to a state in which the voltage applied to the liquid crystal layer is less than the threshold voltage (including the voltage not being applied). The voltage applied state refers to a state in which the voltage applied to the liquid crystal layer is greater than the threshold voltage. In this specification, the voltage non-applied state is also referred to as the voltage non-applied state, and the voltage applied state is also referred to as the voltage applied state.

[0032] The polar angle refers to an angle formed between a target direction (eg, a measurement direction) and a normal direction of the screen of the liquid crystal panel. Azimuth refers to the direction when the direction of the object is projected onto the screen of the liquid crystal panel, and is expressed by the angle (azimuth) formed with the reference azimuth. Here, unless otherwise specified, the reference azimuth (0°) is set to the horizontal right direction of the screen of the liquid crystal panel (i.e., the right direction of the y-axis). For angles and azimuths, the counterclockwise direction from the reference azimuth is taken as a positive angle, and the clockwise direction from the reference azimuth is taken as a negative angle. Both the counterclockwise direction and the clockwise direction indicate the rotation direction when observing the screen of the liquid crystal panel from the observation side (front). In addition, the angle represents the value measured in the state of looking down at the screen of the liquid crystal panel, and refers to the angle of the acute angle unless there is a limitation on the rotation direction, etc.

[0033] The axial orientation of an optical film refers to the orientation of the polarization axis of the polarizing plate in the case of a polarizing plate, and refers to the orientation of the slow axis in the case of a phase difference layer. The polarization axis of a polarizing plate refers to the absorption axis in the case of an absorption-type polarizing plate, and refers to the reflection axis in the case of a reflection-type polarizing plate. The axial orientation of a phase difference layer refers to the orientation of the slow axis in the plane of the phase difference layer unless otherwise specified.

[0034] The phase difference layer refers to a layer in which at least one of the in-plane delay (also referred to as in-plane phase difference) Re and the thickness direction delay (also referred to as thickness direction phase difference) Rth has a value of 10 nm or more. Preferably, it refers to a layer having a value of 20 nm or more. In addition, in this specification, the numerical values ​​recorded as Re and Rth are absolute values ​​unless otherwise specified.

[0035] The in-plane phase difference Re is defined by Re=(nx-ny)×d. The thickness direction retardation Rth is defined by 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 within the plane of each retardation layer, and Nz represents the principal refractive index in the direction perpendicular to the plane of each retardation layer. The slow axis direction is the direction with the largest refractive index, and the fast axis direction is the direction with the smallest refractive index. d represents the thickness of the phase difference layer.

[0036] The A plate is a phase difference plate that satisfies “nx>ny≈nz”. The positive C plate (also called +C-plate) among the C plates is a phase difference plate that satisfies "nz>nx≈ny", and Rth is a positive value. The negative C plate (also called -C-plate) is a phase difference plate that satisfies "nz<nx≈ny", and Rth is a negative value.

[0037] The measurement wavelength of optical parameters such as refractive index and phase difference is 550 nm unless otherwise specified.

[0038] Approximately parallel means that the angle (absolute value) formed by the two is within the range of 0°±10°, preferably within the range of 0°±5°, and more preferably 0° (i.e., parallel in a narrow sense). In addition, approximately orthogonal (or approximately perpendicular) means that the angle (absolute value) formed by the two is within the range of 90°±10°, preferably within the range of 90°±5°, and more preferably 90° (i.e., orthogonal or perpendicular in a narrow sense).

[0039] The following describes a semi-transmissive liquid crystal display device (also simply referred to as a "liquid crystal display device") according to an embodiment of the present invention. The present invention is not limited to the contents described in the following embodiment, and the design can be appropriately changed within the scope of the structure satisfying the present invention.

[0040] (Implementation Method 1) Figure 1 is a schematic cross-sectional view of a liquid crystal display device 1 according to an example of the present embodiment. Figure 2 It is a schematic cross-sectional view showing the liquid crystal display device 1 according to an example of the present embodiment in more detail. Figure 3 1 is a schematic plan view of the entire liquid crystal display device 1 of one example of the present embodiment as viewed from the observation surface side. Figure 1 As shown, the liquid crystal display device 1 includes a first polarizing plate 51, a first phase difference layer 41, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a second phase difference layer 42, and a second polarizing plate 52 in order from the back side to the observation side. The first substrate 10 includes a reflective layer 130 as described later. In addition, the first phase difference layer 41 includes a λ / 4 plate 411 and a λ / 2 plate 412, and the second phase difference layer 42 includes a λ / 4 plate 421 and a λ / 2 plate 422. The second phase difference layer 42 also includes a positive C plate 44. In this embodiment, a TFT substrate is used as the first substrate 10. In addition, a portion or a structure consisting of a structure in which a 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.

[0041] In the liquid crystal display device 1 of the present embodiment, each pixel P has a reflective region Rf for displaying by reflecting light (i.e., a region for displaying in a reflective mode) and a transmissive region Tr for displaying by transmitting light (i.e., a region for displaying in a transmissive mode) (see Figure 4 ). This enables excellent visibility in all environments. Figure 4 1 is a plan view schematically showing conceptually that each pixel P has a reflective region Rf and a transmissive region Tr in the liquid crystal display device 1 of the present embodiment.

[0042] The reflective layer 130 is disposed in the reflective region Rf. For example, light L1 (for example, external light) enters the liquid crystal display device 1 from the observation surface side, and then is reflected by the reflective layer 130 and emitted from the observation surface side (see Figure 2 On the other hand, the reflective layer 130 is not arranged in the transmission region Tr (see Figure 2 For example, when a backlight source 61 is disposed on the back side, the light L2 from the backlight source 61 passes through a region (transmission region Tr) where the reflective layer 130 is not disposed and is emitted from the observation side (see Figure 2 ).

[0043] The ratio (aperture ratio) of the area occupied by the transmission region Tr in each pixel P can be appropriately set according to the purpose, but for example, it is preferably 5% or more and 95% or less when the area of ​​one pixel P is 100%. In addition, the position and shape of the transmission region Tr in the pixel P can also be appropriately set according to the purpose, etc.

[0044] like Figure 3 As shown, the liquid crystal display device 1 includes a plurality of pixels P arranged in a matrix. Typically, the plurality of pixels P 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 four or more. Each pixel P includes a thin film transistor (TFT) 110, a first electrode 121 and a second electrode 122 that can generate a lateral electric field in the liquid crystal layer 20. The drain electrode of the TFT 110 is electrically connected to the corresponding gate wiring (also called scanning wiring) GL, and the gate electrode of the TFT 110 is electrically connected to the corresponding gate wiring (also called signal wiring) SL. The drain electrode of the TFT 110 is electrically connected to the second electrode 122.

[0045] <First substrate> like Figure 2 As shown, the first substrate 10 has 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 in order from the back side to the observation side. Preferably, the first substrate 10 also has a supporting 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 as needed. For example, a first interlayer insulating layer 151 is provided in a manner covering the backplane circuit BP, a second interlayer insulating layer 152 is provided on the first interlayer insulating layer 151 with the reflective layer 130 interposed 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.

[0046] The support substrate 100 is preferably transparent and insulating, and examples of the support substrate 100 include a glass substrate and a plastic substrate.

[0047] The back plate circuit BP is provided on the support substrate 100. The back plate circuit BP is a circuit for driving the plurality of pixels P, and includes the TFT 110, the gate wiring GL, the gate wiring SL, etc. In addition, it also generally includes a gate insulating film.

[0048] TFT110 is provided in each of the plurality of pixels P. As TFT110, a structure including an oxide semiconductor layer as an active layer (also referred to as an oxide semiconductor TFT) is preferred. The oxide semiconductor contained in the oxide semiconductor layer has attracted attention in recent years as an active layer material replacing 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 is formed by a simpler process than the polycrystalline silicon layer, and therefore, it can also be used in devices requiring a large area.

[0049] Since oxide semiconductor TFTs also have excellent cutoff leakage characteristics, they can also be driven to display images at a reduced frequency. For example, when displaying a still image, it is possible to rewrite image data at a frequency of once per second. Such a driving method is called pause drive or low-frequency drive, and can significantly reduce the power consumption of the liquid crystal display device. By using pause drive, touch detection is performed during the period when the image is not being rewritten, thereby suppressing the reduction in the sensitivity of the touch operation caused by the noise from the drive circuit, and can make the S / N ratio (signal to noise ratio) about 10 times the existing one.

[0050] Oxide semiconductor TFTs are also advantageous in reducing the size of TFTs, and therefore a structure in which a memory circuit is provided for each pixel P (also referred to as MIP (Memory In Pixels)) can be appropriately realized.

[0051] 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 in which the c-axis is oriented substantially perpendicular to the layer surface.

[0052] The oxide semiconductor layer may be a single layer or may have a stacked structure of two or more layers. The oxide semiconductor layer having a stacked structure may include an amorphous oxide semiconductor layer and a crystalline oxide semiconductor layer, may include multiple crystalline oxide semiconductor layers with different crystal structures, or may include multiple amorphous oxide semiconductor layers. In the case where the oxide semiconductor layer has a two-layer structure including an upper layer and a lower layer, the energy gap of the oxide semiconductor contained in the lower layer may be different from the energy gap of the oxide semiconductor contained in the upper layer.

[0053] The materials, structures, and film formation methods of amorphous oxide semiconductors and crystalline oxide semiconductors, and the structure of an oxide semiconductor layer having a stacked structure are described in, for example, Japanese Patent Application Laid-Open No. 2014-007399, the entire disclosure of which is incorporated herein by reference.

[0054] As an oxide semiconductor layer, it is preferred to specifically contain 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 preferred. As a ternary oxide of In, Ga and Zn, for example, indium gallium zinc oxide is preferably exemplified. A semiconductor containing a ternary oxide of In, Ga and Zn is called an In-Ga-Zn-O semiconductor, but in this semiconductor, the ratio (composition ratio) of In, Ga and Zn is not particularly limited, for example, In:Ga:Zn=2:2:1, In:Ga:Zn=1:1:1, In:Ga:Zn=1:1:2, etc. are exemplified.

[0055] The In-Ga-Zn-O semiconductor may be amorphous or crystalline. A crystalline In-Ga-Zn-O semiconductor preferably has a structure in which the c-axis is oriented substantially perpendicular to the layer surface.

[0056] The crystal structure of the crystallized In-Ga-Zn-O semiconductor is disclosed in, for example, Japanese Patent Laid-Open No. 2014-007399, Japanese Patent Laid-Open No. 2012-134475, Japanese Patent Laid-Open No. 2014-209727, etc. For reference, the disclosures of Japanese Patent Laid-Open No. 2012-134475 and Japanese Patent Laid-Open No. 2014-209727 are all cited in this specification. The TFT having an In-Ga-Zn-O semiconductor layer has a high mobility (more than 20 times that of an a-SiTFT) and a low leakage current (less than one percent of an a-SiTFT), so it is preferably used as a driving TFT (for example, a TFT included in a driving circuit disposed on a substrate identical to a display region in the periphery of a display region including a plurality of pixels) and a pixel TFT (a TFT disposed in a pixel).

[0057] The oxide semiconductor layer may also include an oxide semiconductor other than an In-Ga-Zn-O semiconductor. For example, a ternary oxide of In, Sn (tin), and Zn may be cited, and preferably, In2O3-SnO2-ZnO; InSnZnO are exemplified. A semiconductor including a ternary oxide of In, Sn, and Zn is called an In-Sn-Zn-O semiconductor. Alternatively, the oxide semiconductor layer may also include In-Al-Zn-O series semiconductors, In-Al-Sn-Zn-O series semiconductors, Zn-O series semiconductors, In-Zn-O series semiconductors, Zn-Ti-O series semiconductors, Cd-Ge-O series semiconductors, Cd-Pb-O series semiconductors, CdO (cadmium oxide), Mg-Zn-O series semiconductors, In-Ga-Sn-O series semiconductors, In-Ga-O series semiconductors, Zr-In-Zn-O series semiconductors, Hf-In-Zn-O series semiconductors, Al-Ga-Zn-O series semiconductors, Ga-Zn-O series semiconductors, In-Ga-Zn-Sn-O series semiconductors, etc.

[0058] The first interlayer insulating layer 151 is provided to cover the backplane circuit BP. The surface of the first interlayer insulating layer 151 on the side of the reflective layer 130 preferably has a concavo-convex shape (also referred to as a concavo-convex surface structure). Thus, the reflective layer 130 can have a concavo-convex surface structure reflecting the shape. The first interlayer insulating layer 151 having a concavo-convex surface structure can be appropriately formed using a photosensitive resin as described in Japanese Patent No. 3394926.

[0059] 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 of a material that reflects light. Among them, it is also preferably formed of a metal material with high reflectivity. As the material of the reflective layer 130, for example, silver alloy, aluminum alloy, aluminum alloy, etc. can be cited.

[0060] The reflective layer 130 preferably has a concave-convex shape reflecting the concave-convex surface structure preferably possessed by the first interlayer insulating layer 151. That is, the reflective layer 130 also preferably has a concave-convex surface structure. This concave-convex surface structure is also called MRS (MicroReflective Structure), which is provided in order to diffusely reflect the surrounding light and realize a white display close to paper white. The concave-convex surface structure is preferably composed of a plurality of convex portions p randomly arranged in such a manner that the center spacing of adjacent convex portions p is greater than 5 μm and less than 50 μm. The center spacing of adjacent convex portions p is more preferably greater than 10 μm and less than 20 μm. The shape of the convex portion p is preferably approximately circular or approximately polygonal when observed from the normal direction of the supporting substrate. The convex portion p preferably occupies, for example, approximately 20 to 40% of the area of ​​a pixel P, and the height of the convex portion p is preferably, for example, greater than 1 μm and less than 5 μm.

[0061] As described above, the transmission region Tr does not have the reflective layer 130. For example, when manufacturing the first substrate 10, after forming the reflective layer 130, a portion of the reflective layer 130 is removed to form the reflective region Rf having the reflective layer 130 and the transmission region Tr not having the reflective layer 130.

[0062] 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 arranged between the first interlayer insulating layer 151 and the second interlayer insulating layer 152.

[0063] Here, the first interlayer insulating layer 151 and the second interlayer insulating layer 152 are preferably formed of an organic insulating material or an inorganic insulating material. For example, as an organic insulating film obtained using an organic insulating material, there can be mentioned organic films such as acrylic resin, polyimide resin, and novolac resin (relative dielectric constant ε=2~5), and their stacked bodies. The film thickness of the organic insulating film is not particularly limited, but for example, it is greater than 2μm and less than 4μm. As an inorganic insulating film obtained using an inorganic insulating material, for example, there can be mentioned inorganic films such as silicon nitride (SiNx), silicon oxide (SiO2) (relative dielectric constant ε=5~7), and their stacked films. The film thickness of the inorganic insulating film is not particularly limited, but for example, it is Above and In addition, a stack of an organic insulating film and an inorganic insulating film may be used. Among them, the first interlayer insulating layer 151 and the second interlayer insulating layer 152 are preferably organic insulating films.

[0064] In addition, from the viewpoint of manufacturing, the interlayer insulating layers 151 and 152 are preferably highly transparent and preferably formed of the same material with high transmittance. In addition, the first interlayer insulating layer 151 which is farther from the observation surface side than the reflective layer 130 may also be in a form with low transmittance and opaque. From the viewpoint of light utilization efficiency, the second interlayer insulating layer 152 may also be in a form with high transparency and may use a material with high transmittance different from that of the first interlayer insulating layer 151.

[0065] The first electrode 121 is arranged on the reflective layer 130 via the second interlayer insulating layer 152, and a dielectric layer 153 is arranged 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 relative to the first electrode 121 and the second electrode 122 (that is, on the back side of the first electrode 121 and the second electrode 122). In addition, among the first electrode 121 and the second electrode 122, in this embodiment, the second electrode 122 is relatively located on the observation surface side, and the first electrode 121 is located on the back side. The electrode relatively located on the observation surface side is also called an upper electrode, and the electrode relatively located on the back side is also called a lower electrode.

[0066] 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 plurality of pixels P. The pixel electrode is electrically connected to the backplane circuit BP. In the present embodiment, the first electrode 121 (lower electrode) is the common electrode CE, and the second electrode 122 (upper electrode) is the pixel electrode PE.

[0067] Preferably, at least one of the first electrode 121 and the second electrode 122 has a plurality of strip-shaped portions SP and a slit S1 between two adjacent strip-shaped portions among the plurality of strip-shaped portions. The strip-shaped portion SP is equivalent to the electrode portion, and the slit S1 is equivalent to the opening portion, but such an electrode is also called a slit electrode or a finger electrode. From the viewpoint of easy generation of a transverse electric field, it is preferred that at least the upper electrode (the pixel electrode PE in the present embodiment) is a slit electrode. In this case, the lower electrode (the common electrode CE in the present embodiment) may also be a planar electrode, i.e., a so-called solid electrode, or a slit electrode.

[0068] The multiple strips SP constituting the slit electrode preferably have their extending directions substantially parallel to each other. In addition, it is preferably a straight line shape extending in the same direction. The straight line shape means that not the outer edge of the strip SP but the center line of the strip SP is a straight line shape, and the center line of the strip SP refers to the line that divides the strip SP into two equal parts in the width direction. The width direction refers to a direction substantially perpendicular to the direction in which the strip SP extends when viewed from above. In addition, the strip SP may also have a bent portion (also called a kinked portion) in the middle (for example, at the end), but it is preferred not to have a bent portion.

[0069] The extending directions of the plurality of strip-shaped portions SP may be different for each pixel, but are preferably the same in two or more adjacent pixels. Of these, it is most preferable that they are the same in all pixels from the viewpoint of maximizing display performance.

[0070] The width L of each strip-shaped portion SP varies depending on the applied voltage, etc., but is preferably 0.3 to 10 μm, for example. More preferably, it is 1 to 5 μm. The interval between two adjacent strip-shaped portions SP (i.e., the interval between the center lines of each strip-shaped portion) also varies depending on the applied voltage, etc., but is preferably 0.3 to 10 μm, for example. More preferably, it is 1 to 5 μm.

[0071] It is preferred that the ratio L / S (also referred to as the L / S condition) of the width L of each strip-shaped portion when viewed from above to the width S of each slit when viewed from above is 0.4 to 0.7 / 1. As a result, the reflectivity of the white display (also referred to as the white reflectivity) is improved, and thus the contrast (also referred to simply as "contrast") is further improved. Specifically, for example, L / S = 1.6 / 3 (i.e., 0.533 / 1), L / S = 2.2 / 4.1 (i.e., 0.537 / 1), and L / S = 3 / 5 (i.e., 0.6 / 1) can be cited.

[0072] Here, the orientation direction of the liquid crystal molecules 21A on the first substrate 10 side when no voltage is applied (i.e., the orientation direction of the liquid crystal molecules 21A defined by the first horizontal orientation film 140) is preferably greater than -30° and less than 30°, with the extension direction of the plurality of strip-shaped portions SP as a reference (0°). When the angle, i.e., the extension direction of the plurality of strip-shaped portions SP, is taken as a reference (0°), and the angle rotated in the clockwise direction is taken as a positive angle (+), and the angle rotated in the counterclockwise direction is taken as a negative angle (-), the angle formed by the orientation directions of the liquid crystal molecules 21A on the first substrate 10 side when no voltage is applied is called the slit angle. For the definition of the slit angle, refer to Figure 5 Provide explanation. Figure 5 This is a diagram for explaining the slit angle of the liquid crystal molecules. The (n) added at the end of the reference numeral of the liquid crystal molecule indicates a negative type. In addition, in this specification, the liquid crystal molecules 21 near the first horizontal alignment film 140 (i.e., the liquid crystal molecules on the first substrate 10 side) are also referred to as liquid crystal molecules 21A, and the liquid crystal molecules 21 near the second horizontal alignment film 340 (i.e., the liquid crystal molecules on the second substrate 30 side) are also referred to as liquid crystal molecules 21B.

[0073] As described later, a negative liquid crystal material (and liquid crystal molecules) is used in this embodiment, but in the case of negative liquid crystal molecules, the orientation 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. However, as described later, the dielectric constant of the long axis direction of the negative liquid crystal is larger than the dielectric constant of the long axis direction, so the direction orthogonal to the long axis direction of the liquid crystal molecules 21A, that is, the short axis direction is used as a reference (0°). In this case, when the short axis direction of the liquid crystal molecules 21A is parallel to the extension direction of the plurality of strip-shaped portions SP, the slit angle is 0° (refer to Figure 5 When the extending directions of the plurality of strip-shaped portions SP are rotated clockwise with the short axis direction of the liquid crystal molecule 21A as a reference (0°), the slit angle becomes a positive angle (+) (see Figure 5When the extending directions of the plurality of strip-shaped portions SP are rotated counterclockwise with the short axis direction of the liquid crystal molecule 21A as a reference (0°), the slit angle becomes a negative angle (-) (see Figure 5 in the “Negative (-)” column).

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

[0075] The preferred range of the slit angle varies depending on the conditions of the width L of each strip-shaped portion SP and the width S of each slit S1 (also referred to as the L / S condition), the twist angle, whether the liquid crystal material is positive or negative, etc. In particular, in a single domain structure, the reflectivity (particularly white reflectivity) can be maximized by selecting the optimal slit angle according to the L / S condition.

[0076] Figure 6 as well as Fig. 7A The following example is shown: when the extending direction of the gate wiring SL is taken as a reference (0°), the angle rotated in the clockwise direction is taken as a positive angle (+), and the angle rotated in the counterclockwise direction is taken as a negative angle (-), the extending direction of the plurality of strip-shaped portions SP (this angle is referred to as angle X) is 0°. In addition, examples where the angle X is -10°, +10°, -90°, -100°, and -80° are respectively taken as Figure 7B , Figure 7C , Fig.7D , Fig. 7E , Figure 7F The angle X is 0° (see Figure 6 as well as Fig. 7A ) corresponds to the mode in which the extending direction of the plurality of strip-shaped portions SP is parallel to the extending direction of the gate wiring SL, and the mode in which the angle is -90° (refer to Fig.7D ) corresponds to a mode in which the extending direction of the plurality of strip-shaped portions SP is parallel to the extending direction of the gate wiring GL. Figure 6 as well as 7A to 7F is a plan view schematically showing a specific example of a pixel. Figure 6 is a plan view schematically showing a structural example of a pixel, 7A to 7F It is a plan view schematically showing an example of pixel arrangement. 7A to 7F The twisted orientation of the liquid crystal molecules 21 is also shown.

[0077] The first electrode 121 and the second electrode 122 are preferably formed of a transparent conductive material. Examples of the transparent conductive material include indium tin oxide (ITO), indium zinc oxide (IZO (registered trademark)), and a mixture thereof.

[0078] exist Figure 2 In the manner shown, the pixel electrode PE (the second electrode 122 in this embodiment) is electrically connected to the backplane circuit (more specifically, 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 formed of the same material (metal film, etc.) as the reflective film 130. A first contact hole CH1 is formed in the first interlayer insulating layer 151 to expose a portion of the backplane circuit BP (more specifically, at least a portion 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. In addition, a second contact hole CH2 is formed in the second interlayer insulating layer 152 to expose a portion 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.

[0079] The dielectric layer 153 is provided to cover the first electrode 121. The dielectric layer 153 is preferably formed of an inorganic insulating material. The inorganic insulating film obtained using the inorganic insulating material is as described above.

[0080] 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 .

[0081] The first horizontal alignment film 140 and the second horizontal alignment film 340 described later are respectively subjected to an alignment treatment to define the alignment azimuth (also referred to as alignment direction) of the liquid crystal molecules 21 contained in the liquid crystal layer 20. The alignment treatment is preferably performed by, for example, a photo-alignment treatment or a rubbing treatment. In the photo-alignment treatment, a photo-decomposable photo-alignment film material can be used, and in the rubbing treatment, an alignment film material such as polyimide is preferably used.

[0082] The first horizontal alignment film 140 and the second horizontal alignment film 340 are both horizontal alignment films that align the liquid crystal molecules 21 in a horizontal direction relative 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°.

[0083] The orientation of the liquid crystal molecules 21 defined by the first horizontal alignment film 140 is different from the orientation of the liquid crystal molecules 21 defined by the second horizontal alignment film 340. Therefore, the liquid crystal layer 20 is twisted when no voltage is applied (see Figure 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 is changed by the transverse electric field (fringe electric field).

[0084] However, in the present embodiment, the structure in which the pixel electrode PE is disposed above the common electrode CE is described, but in a relatively large liquid crystal display device, that is, a liquid crystal display device in which the area of ​​the pixel P is relatively large, it is preferred that the pixel electrode PE is disposed above the common electrode CE. In this structure (also referred to as the V2 structure), there is no need to form a slit in the common electrode CE that becomes the lower electrode, and therefore, compared with the structure in which the common electrode CE is disposed above the pixel electrode PE (also referred to as the V3 structure), the increase in the resistivity (surface resistivity) of the common electrode CE is suppressed, and thus, the weakening of the edge electric field applied to the liquid crystal layer 20 is suppressed. In the case where the pixel electrode PE is made into a slit electrode by this structure (V2 structure), the resistivity of the pixel electrode PE increases, and a voltage input from the outside is applied to the pixel electrode PE, so it is easy to reduce the influence caused by the increase in resistivity (that is, the weakening of the edge electric field is suppressed). In addition, in order to suppress the increase in the resistivity of the common electrode CE, it is also considered to use low-resistance wiring formed by a metal material (for example, connecting the low-resistance wiring to the common electrode). However, in such a structure, sometimes negative effects on the display (such as glare, rainbow diffraction, interference patterns) are caused by mirror reflection caused by the low-resistance wiring, etc., and it is necessary to shield the light through a black matrix, etc., and sometimes the reflective aperture ratio cannot be fully increased.

[0085] For the structure in which the pixel electrode PE is arranged above the common electrode CE, in addition, there is no common electrode CE in the area where the second contact hole CH2 is formed, so the area does not contribute to reflective display, and the reflectivity can be reduced compared with the structure in which the common electrode CE is arranged above the pixel electrode PE. The area of ​​the area such as the contact hole that does not contribute to reflective display needs to be a certain degree regardless of the size of the area of ​​the pixel P. Therefore, for the proportion of the area that does not contribute to reflective display in the pixel P, the smaller the area of ​​the pixel P (that is, the higher the clarity), the higher the reduction in the above-mentioned reflectivity. In other words, in a relatively large liquid crystal display device, it is easy to make the proportion of the area that does not contribute to reflective display in the pixel P lower, so it is easy to suppress the above-mentioned reduction in reflectivity. Based on these reasons, in a relatively large liquid crystal display device, the structure in which the pixel electrode PE is arranged above the common electrode CE is advantageous.

[0086] On the other hand, as mentioned above, the smaller the area of ​​the pixel P (that is, the higher the clarity) is, the higher the reflectivity reduction caused by the fact that the area where the second contact hole CH2 is formed does not contribute to the reflective display. Therefore, in a relatively high-definition liquid crystal display device, that is, a liquid crystal display device in which the area of ​​the pixel P is relatively small, it is preferred that the common electrode CE is arranged above the pixel electrode PE (refer to variant example 1 of embodiment 1 described later).

[0087] <Liquid crystal layer> The liquid crystal layer 20 is located between the first substrate 10 and the second substrate 30, and includes a negative liquid crystal material. The negative liquid crystal material refers to a liquid crystal material with a negative dielectric anisotropy, that is, a nematic liquid crystal material with a negative dielectric anisotropy Δε. In addition, the positive liquid crystal material refers to a liquid crystal material with a positive dielectric anisotropy, that is, a nematic liquid crystal material with a positive dielectric anisotropy Δε. The dielectric anisotropy Δε is the dielectric constant ε of the liquid crystal molecule 21 in the long axis direction. / / The dielectric constant ε along the short axis ⊥ The difference (i.e. ε / / -ε ⊥ ).

[0088] The birefringence Δn of the negative liquid crystal material is preferably, for example, less than 0.123, and more preferably 0.12. It is particularly preferred that the thickness d of the liquid crystal layer 20 is greater than 2 μm, and Δn is less than 0.123. It is further preferred that d is greater than 2.5 μm, and Δn is less than 0.098. In addition, the dielectric anisotropy Δε of the liquid crystal material is preferably, for example, less than -5. In addition, the VR curve (threshold value, reflectivity Max value, etc.) of the one with a smaller Δε (or a larger absolute value of Δε) is shifted toward the low voltage side.

[0089] The liquid crystal layer 20 may further contain a chiral agent as necessary. The liquid crystal layer 20 can be formed by, for example, a dropping method.

[0090] The thickness d (also called the cell gap or cell thickness) of the liquid crystal layer 20 is preferably less than 3.6 μm. More preferably, it is 2.0 to 3.4 μm. In addition, from the viewpoint of response speed, it is preferably less than 3 μm. In addition, the smaller the cell thickness, the less the amount of material can be used, so it is preferred from the viewpoint of cost reduction. However, if it is too small, sometimes the display quality cannot be further improved due to uneven cell thickness and foreign matter, which becomes a compromise with the occurrence rate of poor display quality. From the viewpoint of yield, it is preferably more than 2 μm as mentioned above.

[0091] The retardation dΔn of the liquid crystal layer 20, i.e., the product of the thickness d of the liquid crystal layer 20 and the birefringence Δn of the liquid crystal material, is preferably 230 nm to 260 nm. From the viewpoint of further improving the contrast, it is more preferably 232 nm to 250 nm, further preferably 235 nm to 246 nm, and particularly preferably 236 nm to 245 nm.

[0092] The liquid crystal layer 20 may be in a multi-domain alignment such as a dual-domain alignment, but is preferably in a single-domain alignment (also referred to as a monodomain alignment) from the viewpoint of maximizing the liquid crystal mode reflection efficiency and the liquid crystal mode transmission efficiency.

[0093] <Second substrate> The second substrate 30 includes a second horizontal alignment film 340, which is disposed opposite to the first substrate 10 via the liquid crystal layer 20 and in contact with the liquid crystal layer 20. Preferably, the second substrate 30 further includes a supporting substrate 300 and a color filter layer 310. Figure 2 As shown, the second substrate 30 has a second horizontal alignment film 340, a color filter layer 310, and a support substrate 300 in order from the liquid crystal layer 20 side. Preferably, the second substrate 30 also has a plurality of columnar spacers (not shown). In addition, the first substrate 10 may also have a plurality of columnar spacers.

[0094] The support substrate 300 is preferably transparent and insulating, and examples of the support substrate 300 include a glass substrate and a plastic substrate. Figure 2 In the embodiment, a high-resistance transparent conductive film is formed on the surface of the phase difference layer 40 side of the support substrate 300 to prevent electrostatic adhesion of the liquid crystal unit. The high-resistance transparent conductive film may also be a multilayer structure in order to suppress a decrease in transmittance or an increase in reflectance.

[0095] Typically, the color filter layer 310 includes: a red color filter, which is disposed in an area corresponding to a red pixel and transmits red light; a green color filter, which is disposed in an area corresponding to a green pixel and transmits green light; and a blue color filter, which is disposed in an area corresponding to a blue pixel and transmits blue light. However, the types of color filters may be two or less, or four or more. In addition, when color display is not performed, the color filter layer 310 is omitted.

[0096] An outer coating layer (also referred to as a planarization layer) covering the color filter layer 310 may also be provided as required. In addition, depending on the material forming the electrode (e.g., a transparent conductive material), the material forming the interlayer insulating layer, the dielectric layer, and the material forming the alignment film, sometimes the white display has a yellow tint. Alternatively, in this case, the chromaticity adjustment (i.e., blue shift) may be performed by forming an outer coating layer using a blue resist, so that the chromaticity of the white display is close to the chromaticity of, for example, a D65 light source. The D65 light source is the CIE standard light source D65.

[0097] <Phase difference layer> The first phase difference layer 41 is located between the first substrate 10 and the first polarizing plate 51, and includes a λ / 4 plate 411 and a λ / 2 plate 412 (see Figure 1 as well as Figure 2 ). In addition, the second phase difference layer 42 is located between the second substrate 30 and the second polarizing plate 52, and includes a λ / 4 plate 421, a λ / 2 plate 422, and a positive C plate 44 (refer to Figure 1 as well as Figure 2 ). As for the positional relationship between the λ / 4 plate and the λ / 2 plate in each phase difference layer, in the first phase difference layer 41, it is preferred that the λ / 2 plate 412 and the λ / 4 plate 411 are arranged in this order from the back side, and in the second phase difference layer 42, it is preferred that the λ / 2 plate 422 and the λ / 4 plate 421 are arranged in this order from the observation side.

[0098] The λ / 4 plate is a phase difference plate that gives an in-plane phase difference of 1 / 4 wavelength to incident light of wavelength λ, and is also called a λ / 4 wavelength plate or QWP (Quarter-Wave Plate). Specifically, the λ / 4 plate can convert linear polarized light into circular polarized light, or convert circular polarized light into linear polarized light. For example, linear polarized light incident on the λ / 4 plate becomes circular polarized light when it is emitted.

[0099] The λ / 2 plate is a phase difference plate that gives an in-plane phase difference of 1 / 2 wavelength to incident light of wavelength λ, and is also called a λ / 2 wavelength plate, a half-wavelength plate, or an HWP (Half-Wave Plate). Specifically, the λ / 2 plate can rotate the vibration direction of the incident light by approximately 90°. For example, circularly polarized light incident on the λ / 2 plate becomes circularly polarized light with the opposite rotation direction when it is emitted.

[0100] The first λ / 4 plate 411 and the second λ / 4 plate 421 preferably have substantially the same in-plane phase difference Re. Substantially the same means that the difference in their in-plane phase difference Re is less than 5 nm. The difference in their in-plane phase difference Re is preferably less than 1 nm.

[0101] The first λ / 2 plate 412 and the second λ / 2 plate 422 preferably have substantially the same in-plane phase difference Re. Substantially the same means that the difference in their in-plane phase difference Re is less than 5 nm. The difference in their in-plane phase difference Re is preferably less than 1 nm.

[0102] As λ / 4 plates 411, 421 and λ / 2 plates 412, 422, a general phase difference plate can be used. More specifically, it is preferred to use a phase difference plate that is generally circulated, such as a circular polarizing plate as an anti-reflection film. In the present invention, it is preferred to control the optical axis setting of each optical film to be within a predetermined range described later, so that as a λ / 4 plate and a λ / 2 plate, even if a general phase difference plate is used without using a special phase difference plate, it can become a semi-transmissive liquid crystal display device of a lateral electric field mode and improve contrast and field angle, and it is also useful as an embedded (in-cell) type touch panel, therefore, it is possible to achieve cost reduction. In particular, from the user's perspective, it is possible to reduce the total cost, therefore, it is very useful. For the semi-transmissive liquid crystal display device of the present invention, it is not only used as a built-in touch panel such as an embedded (in-cell) type, but also can achieve cost reduction when used as an external touch panel.

[0103] Specifically, it is preferable to use uniaxial A plates as the λ / 4 plates 411 and 421 and the λ / 2 plates 412 and 422 .

[0104] As described above, in the present invention, in addition to each phase difference layer 41, 42 including a λ / 4 plate and a λ / 2 plate, at least one of the phase difference layers 41, 42 also includes a positive C plate, whereby in the resulting liquid crystal display device, the viewing angle characteristics are excellent and a high contrast ratio can be achieved. In particular, the brightness protrusion (also called black tone protrusion) during black display is fully suppressed, and the viewing angle during black display is enlarged. From the viewpoint of further exerting the above-mentioned effects, it is preferred that the positive C plate is located between the λ / 4 plate and the λ / 2 plate. In particular, in the case where the phase difference layer includes a positive C plate, this configuration is preferred. In the present embodiment, only the second phase difference layer 42 includes a positive C plate 44, but in this case, it is preferred that there are, in order from the liquid crystal layer 20 (and the second substrate 30) side, a λ / 4 plate 421, a positive C plate 44, and a λ / 2 plate 422 (see Figure 1 ).

[0105] The positive C plate 44 (and 43 , 45 , 46 , etc. described later) may be composed of a single film, or may be a laminate of two or more retardation films.

[0106] In this specification, the part (structure) sandwiched by layers other than the positive C plate and functioning as a positive C plate is counted as "one positive C plate". At this time, it does not matter whether the positive C plate is a laminated body. Therefore, for example, in the case where the phase difference layer includes a λ / 4 plate, a positive C plate of a multilayer structure, and a λ / 2 plate in sequence, it is referred to as "the phase difference layer has one positive C plate". In addition, in the case where the phase difference layer includes a λ / 4 plate, two commercially available positive C plates, and a λ / 2 plate in sequence, it is also referred to as "the phase difference layer has one positive C plate". In the case where the phase difference layer has a λ / 4 plate, a first positive C plate (regardless of whether it is a laminated body), a λ / 2 plate, and a second positive C plate (regardless of whether it is a laminated body) in sequence, it is referred to as "the phase difference layer has two positive C plates".

[0107] As the positive C plate 44 (and 43, 45, 46, etc. described later), for example, it is preferable to use a structure obtained by stretching a film containing a material having negative intrinsic birefringence as a component in both the longitudinal and transverse directions, a structure coated with a liquid crystal material such as a nematic liquid crystal, etc. As the material having negative intrinsic birefringence, for example, a resin composition containing an acrylic resin and a styrene resin, polystyrene, polyvinyl naphthalene, polyvinyl biphenyl, polyvinyl pyridine, polymethyl methacrylate, polymethyl acrylate, N-substituted maleimide copolymer, polycarbonate having a fluorene skeleton, triacetyl cellulose (especially a structure with a low degree of acetylation), etc.

[0108] Specific examples of the positive C plate 44 (and 43 , 45 , 46 , etc.) include positive C plates manufactured by ENEOS or Hayashi Telempu, and positive-C retardation films manufactured by Nippon Kayaku Co., Ltd.

[0109] From the viewpoint of further exerting the viewing angle improvement effect, the thickness direction retardation Rth of the positive C plate 44 (and 43) is preferably 150 to 270 nm, more preferably 160 to 250 nm, and even more preferably 170 to 240 nm.

[0110] The thickness of each positive C plate 44 (and 43) is preferably, for example, 0.1 to 100 μm. If it is in this range, the mechanical strength and display uniformity are more excellent. It is more preferably 0.1 to 80 μm, and further preferably 0.1 to 50 μm. In addition, when the positive C plate 44 (and 43) has a stacked structure, it is preferably set to the above-mentioned range for the total thickness of the whole, and the thickness of each phase difference film may be the same or different.

[0111] The phase difference layer having a positive C plate (corresponding to the second phase difference layer 42 in this embodiment) may also have a positive C plate different from the positive C plate (referred to as a second positive C plate). In this case, it is preferred that the second positive C plate is located between the λ / 2 plate and the polarizing plate. In addition, in the later-described embodiment 2, a method in which the first phase difference layer 41 has a first positive C plate and a second positive C plate is described in detail, and in the later-described embodiment 3, a method in which the first phase difference layer 41 and the second phase difference layer 42 respectively have a first positive C plate and a second positive C plate is described in detail.

[0112] In the present invention, from the viewpoint of making the viewing angle characteristics and contrast better, it is particularly preferred to satisfy any one of the following (i) to (iii). In this embodiment, the form satisfying the following (i) is described in detail (refer to Figure 2 ). In the second embodiment described later, a form satisfying the following (ii) will be described in detail, and in the third embodiment, a form satisfying the following (iii) will be described in detail. (i) The second retardation layer 42 includes a positive C plate, and the first retardation layer 41 does not include a positive C plate. (ii) The second retardation layer 42 includes one positive C plate, and the first retardation layer 41 includes two positive C plates. (iii) The first retardation layer 41 and the second retardation layer 42 each include two positive C plates.

[0113] <Polarizing plate> The first polarizing plate 51 is located on the back side of the first retardation layer 41 (see Figure 1 as well as Figure 2 ). In addition, the second polarizing plate 52 is located closer to the observation surface side than the second phase difference layer 42 (refer to Figure 1 as well as Figure 2 ). Polarizing plates 51 and 52 may be circular polarizing plates or linear polarizing plates. Here, a linear polarizing plate refers to a polarizing plate having the function of extracting polarized light (linear 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 preferred.

[0114] Polarizing plates 51 and 52 may also be absorption-type polarizing plates or reflection-type polarizing plates. An absorption-type polarizing plate is a polarizing plate that has the function of absorbing light vibrating in a specific direction and transmitting polarized light (linear polarized light) vibrating in a direction perpendicular thereto. A reflection-type polarizing plate is a polarizing plate that has the function of reflecting light vibrating in a specific direction and transmitting polarized light (linear polarized light) vibrating in a direction perpendicular thereto. Among them, an absorption-type polarizing plate is preferred. In particular, an absorption-type linear polarizing plate is preferably used.

[0115] As an absorption type polarizing plate, for example, a polarizing plate in which a polyvinyl alcohol film is dyed and an anisotropic material such as an iodine complex (or dye) is adsorbed and then stretched and oriented can be cited. Usually, in order to ensure mechanical strength and moisture and heat resistance, the polyvinyl alcohol film is put into practical use in a state where a protective film such as a triacetyl cellulose film is laminated on both sides. In addition, as a reflection type polarizing plate, for example, a film laminated with multiple dielectric thin films, a film laminated with multiple thin films with different refractive index anisotropy, a nanowire grid polarizing plate, a polarizing plate using selective reflection of cholesteric liquid crystal, etc. can be cited.

[0116] <Other structures, etc.> In the liquid crystal display device 1 of the present embodiment, the liquid crystal layer 20 is displayed in a transverse electric field mode in which the liquid crystal layer 20 is twisted when no voltage is applied. Thus, the contrast of the reflective display can be sufficiently improved. Preferably, the twist angle θ1 of the liquid crystal layer 20 when no voltage is applied is greater than 70° and less than 85°. A more preferred range will be described later.

[0117] The twist angle θ1 of the liquid crystal layer 20 is an angle formed by the orientation direction of the liquid crystal molecules 21 specified by the first horizontal alignment film 140 and the orientation direction of the liquid crystal molecules 21 specified by the second horizontal alignment film 340. That is, it is an angle formed by the long axis direction of the liquid crystal molecules 21A near the first horizontal alignment film 140 (also referred to as the liquid crystal molecules 21A on the first substrate 10 side when no voltage is applied) and the long axis direction of the liquid crystal molecules 21B near the second horizontal alignment film 340 (also referred to as the liquid crystal molecules 21B on the second substrate 30 side when voltage is applied).

[0118] From the viewpoint of further improving the contrast, the liquid crystal display device 1 is preferably in a normally black mode. The normally black mode is a display mode in which a black display is displayed when no voltage is applied, and a white display is displayed when a voltage is applied.

[0119] The liquid crystal display device 1 preferably further includes a light source. In the present embodiment, a light source 61 (also referred to as a backlight) is further provided on the back side of the liquid crystal layer 20 (see Figure 1 The light source 61 (backlight source) is not particularly limited as long as it is a structure for irradiating light, and may be a direct-down type, an edge type, or any other type. Specifically, for example, it is preferably a structure having a light source such as a light emitting diode (LED), a light guide plate, and a reflector, and may also have a diffuser plate and a prism sheet.

[0120] Alternatively, the liquid crystal display device 1 may be a structure composed of multiple components, such as TCP (tape carrier package), PCB (printed wiring board), etc., in addition to the above-mentioned components, optical films such as viewing angle magnification film and brightness enhancement film, outer frame (frame), etc., and other components may be incorporated depending on the components. These are not particularly limited, and structures commonly used in the field of liquid crystal display devices can be used, so the description is omitted.

[0121] <Preferred optical setting example> The following further describes the preferred optical axis settings of each optical film (i.e., polarizing plate and phase difference layer) and the verification results for achieving the settings. As a polarizing plate, an absorption-type polarizing plate is used. In addition, as the liquid crystal layer 20, a liquid crystal layer with a single-domain structure for normally black display is envisioned, and as a liquid crystal material constituting the liquid crystal layer 20, a negative liquid crystal material is used. In addition, the slow axis angle of the positive C plate is the film normal direction (i.e., 90° when the orientation direction of the liquid crystal molecules 21A defined by the first horizontal orientation film 140 is 0°), and therefore, the study was conducted in a manner without a positive C plate. In the case of a positive C plate, the preferred settings are also the same.

[0122] (I) Optimal settings Figure 8 The liquid crystal display device 1 includes a first polarizing plate 51, a first retardation layer 41, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a second retardation layer 42, and a second polarizing plate 52 in this order from the back side toward the viewing side (see Figure 1 ) is a top view conceptually showing the relationship between the long axis direction of the liquid crystal molecules 21A of the liquid crystal layer 20 when no voltage is applied and the optical axes of each optical film (i.e., the in-plane slow axes of the λ / 4 plate and the λ / 2 plate and the polarization axis of the polarizing plate). Figure 8 In FIG. 1 , as the liquid crystal molecules 21 , liquid crystal molecules 21A near the first horizontal alignment film 140 and liquid crystal molecules 21B near the second horizontal alignment film 340 are described.

[0123] In this specification, unless otherwise specified, each angle (such as twist angle, optical axis angle, etc.) is an angle when the twist direction is positive (in the counterclockwise direction) by comparing the liquid crystal panel 1X to the dial of a clock, taking the orientation direction of the liquid crystal molecules 21A defined by the first horizontal alignment film 140 as the reference direction, that is, the 0° direction (3 o'clock direction), and the twist direction is positive (in the counterclockwise direction) (refer to Fig. 9 ). Fig. 9 It is a diagram for explaining the optical axis angle of the optical film.

[0124] The twist angle θ1 of the liquid crystal layer 20 when no voltage is applied is preferably 70° to 85°, more preferably 75° to 85°, further preferably 80° to 85°, particularly preferably 81° to 84°, and most preferably around 83° (approximately 83°).

[0125] The angle of the polarization axis 51AA of the first polarizing plate 51 is ( Figure 8θ2) in ( θ2 ) is preferably 33.6° to 40.2°, more preferably 34.1° to 39.7°, further preferably 34.8° to 39.0°, and particularly preferably 35.2° to 38.6°.

[0126] The angle of the in-plane slow axis 412SA of the first λ / 2 plate 412 is ( Figure 8 θ3) in ( θ3 ) is preferably 48.8° to 52.1°, more preferably 49.1° to 51.8°, further preferably 49.4° to 51.5°, and particularly preferably 49.6° to 51.3°.

[0127] The angle of the in-plane slow axis 411SA of the first λ / 4 plate 411 is ( Figure 8 θ4) in ( θ4 ) is preferably -74.8° to -68.2°, more preferably -74.3° to -68.7°, further preferably -73.6° to -69.4°, and particularly preferably -73.2° to -69.9°.

[0128] Therefore, the polarization axis 51AA of the first polarizing plate 51, the in-plane slow axis 412SA of the first λ / 2 plate 412, and the in-plane slow axis 411SA of the first λ / 4 plate 411 are preferably located at angles of 33.6° to 40.2°, 48.8° to 52.1°, and -74.8° to -68.2°, respectively, more preferably located at angles of 34.1° to 39.7°, 49.1° to 51.8°, and -74.3° to -68.7°, respectively, further preferably located at angles of 34.8° to 39.0°, 49.4° to 51.5°, and -73.6° to -69.4°, respectively, and particularly preferably located at angles of 35.2° to 38.6°, Angles of 49.6°~51.3°, -73.2°~-69.9°.

[0129] The angle of the in-plane slow axis 421SA of the second λ / 4 plate 421 is ( Figure 8 θ4) in ( θ4 ) is preferably -26.9° to -22.9°, more preferably -26.5° to -23.5°, further preferably -26.0° to -24.0°, and particularly preferably -25.5° to -24.5°.

[0130] The angle of the in-plane slow axis 422SA of the second λ / 2 plate 422 is ( Figure 8 θ3) in ( θ3 ) is preferably -51.5° to -47.5°, more preferably -51.0° to -48.0°, further preferably -50.5° to -48.5°, and particularly preferably -50.0° to -49.0°.

[0131] The angle of the polarization axis 52AA of the second polarizing plate 52 is ( Figure 8θ2) in ( θ2 ) is preferably -69.5° to -64.0°, more preferably -69.2° to -65.5°, further preferably -68.9° to -66.5°, and particularly preferably -68.6° to -67.5°.

[0132] Therefore, the polarization axis 52AA of the second polarizing plate 52, the in-plane slow axis 422SA of the second λ / 2 plate 422 and the in-plane slow axis 421SA of the second λ / 4 plate 421 are preferably located at angles of -69.5° to -64.0°, -51.5° to -47.5° and -26.9° to -22.9°, more preferably located at angles of -69.2° to -65.5°, -51.0° to -48.0°, -26.5° to -23.5°, further preferably located at angles of -68.9° to -66.5°, -50.5° to -48.5°, -26.0° to -24.0°, and particularly preferably located at angles of -68.6° to -67.5°, -50.0° to -49.0°, -25.5° to -24.5°, respectively.

[0133] (II) Verification results based on optical simulation The above-mentioned preferred setting was found by the inventors of the present application through verification using optical simulation. The simulation was performed using Shintech Optics Master manufactured by Shintech Co., Ltd. The verification results are described below.

[0134] Assume that a liquid crystal display device 1 is provided with a structure in which a λ / 4 plate 411, a λ / 2 plate 412, and a polarizing plate 51 are provided in order from the liquid crystal panel 1X side on the back side of a reflective liquid crystal panel 1X using a negative liquid crystal material, and a λ / 4 plate 421, a λ / 2 plate 422, and a polarizing plate 52 are provided in order from the liquid crystal panel 1X side on the observation side of the liquid crystal panel 1X (see Figure 1 ). The retardation dΔn of the liquid crystal layer 20 is 245 nm. As the λ / 4 plates 411 and 421, uniaxial phase difference plates with a retardation Re of 140 nm are used, and as the λ / 2 plates 412 and 422, uniaxial phase difference plates with a retardation Re of 270 nm are used, and the wavelength dispersion of these phase difference plates is set to be flat.

[0135] The orientation direction of the liquid crystal molecules 21A defined by the first horizontal alignment film 140 is set to the 90° direction (12 o'clock direction), and the twist angle θ1 is fixed to 83°. Note that this verification was performed in a state where no voltage was applied.

[0136] (II-1) The optical axis settings of the optical film (also called the surface side optical film) located on the observation side of the liquid crystal panel 1X are fixed to the optimal values ​​of the optical axis settings in the reflective liquid crystal display device. This is shown in Table 1. Then, the optical axis settings of the optical film (also called the back side optical film) located on the back side of the liquid crystal panel 1X are changed at intervals of 0.5° from a predetermined starting angle to an end angle, and the transmission mode efficiency of the black display (that is, when no voltage is applied) is calculated. The calculation range is shown in Table 2. In addition, the transmission mode efficiency of the black display is also referred to as the "black transmission mode efficiency". During the calculation, only one of the optical axes is changed, and the other optical axes are fixed and the calculation is repeated.

[0137] [Table 1] Surface side optical film Optical axis Reference numerals angle Polarizing plate 52 Absorption axis 52AA -68.3° λ / 2 Plate 422 Slow Axis 422SA -49.5° λ / 4 plate 421 Slow Axis 421SA -24.9°

[0138] [Table 2] Back side optical film start Finish interval λ / 4 plate 411 -90° 90° 0.5° λ / 2 plate 412 -90° 90° 0.5° Polarizing plate 51 -90° 90° 0.5°

[0139] Here, the transmission mode efficiency is obtained by the following formula (1): Transmission mode efficiency (%) = (brightness with surface polarizing plate) / (brightness without surface polarizing plate) × 100. The surface polarizing plate refers to the second polarizing plate 52 located on the viewing side of the liquid crystal panel 1X.

[0140] An example of the calculation result is Fig.11 shown. Fig.11 The graph shows the black transmission mode efficiency when the in-plane slow axis 411SA of the first λ / 4 plate 411 is fixed at −71.5°, the in-plane slow axis 412SA of the first λ / 2 plate 412 is fixed at 50.5°, and the polarization axis 51AA of the first polarizing plate 51 is changed.

[0141] (II-2) The black transmission mode efficiency was calculated by changing the vicinity of each axis setting at which the black transmission mode efficiency calculated in (II-1) was the minimum by 0.1°, and the black transmission mode efficiency was calculated. The calculation range is shown in Table 3.

[0142] [Table 3] Back side optical film start Finish interval λ / 4 plate 411 -80° -65° 0.1° λ / 2 plate 412 45° 60° 0.1° Polarizing plate 51 30° 45° 0.1°

[0143] The calculation results are as follows FIG. 12A to FIG. 12C shown. Fig. 12A The graph shows the black transmission mode efficiency when the in-plane slow axis 412SA of the first λ / 2 plate 412 is fixed at 50.4° and the polarization axis 51AA of the first polarizing plate 51 is fixed at 37.0°, and the in-plane slow axis 411SA of the first λ / 4 plate 411 is changed. Fig. 12BThe graph shows the black transmission mode efficiency when the in-plane slow axis 411SA of the first λ / 4 plate 411 is fixed at −71.4° and the polarization axis 51AA of the first polarizing plate 51 is fixed at 37.0°, and the in-plane slow axis 412SA of the first λ / 2 plate 412 is changed. Fig. 12C The graph shows the black transmission mode efficiency when the in-plane slow axis 411SA of the first λ / 4 plate 411 is fixed at −71.4° and the in-plane slow axis 412SA of the first λ / 2 plate 412 is fixed at 50.4° and the polarization axis 51AA of the first polarizing plate 51 is changed.

[0144] (II-3) The axis at which the black transmission mode efficiency calculated in the above (II-2) becomes the minimum is set as the optimal value. This is shown in Table 4.

[0145] [Table 4]

[0146] exist FIG. 12A to FIG. 12C In each of the graphs, the ranges where the black transmission mode efficiency is 0.16% or less, 0.12% or less, 0.08% or less, and 0.06% or less are respectively the preferred range (corresponding to the range where black display can be performed), the more preferred range, the further preferred range, and the particularly preferred range for the above-mentioned optical axis settings. In addition, according to the results of 3D simulation ("Shintech LCD Master3D" produced by Shintech), if the transmission mode efficiency during white display is set to 12%, the contrast ratios in the preferred range, the more preferred range, the further preferred range, and the particularly preferred range for each optical axis setting are respectively 75 or more, 100 or more, 150 or more, and 200 or more.

[0147] Fig.10 The most preferable optical axis setting from the viewpoint of contrast improvement is shown. Fig.10 1 and 2 are diagrams conceptually showing the most preferable optical axis settings. In this optical axis setting diagram, the in-plane phase difference Re of the λ / 4 plates 411 and 421 is 140 nm, and the in-plane phase difference Re of the λ / 2 plates 412 and 422 is 270 nm.

[0148] <Application Examples> The liquid crystal display device 1 of this embodiment is applicable to various applications. Among them, it can also be preferably used for a touch panel. Regardless of whether it is applied to an external touch panel or a built-in touch panel, it can be lower cost than existing touch panels and improve contrast, so it is more useful. Among them, it can be applied to a built-in touch panel, especially an in-cell touch panel. If the liquid crystal display device 1 of this embodiment is used in this way, an in-cell touch panel capable of displaying in a reflective mode can be appropriately realized.

[0149] It is possible to realize an in-cell touch panel capable of displaying a reflective mode, so that, for example, the frame wiring area required in the external touch panel is not required, so that a narrow frame can be realized. In addition, the touch panel function can be equipped without a glass cover, so it can also contribute to thinness and lightness. In addition, the touch function and the display function are driven in a time-division manner, so the LCD (liquid crystal display) noise, which can be the largest noise source in the touch panel, is not received. That is, no flickering mode is generated, so the adjustment (adjustment) of the touch signal is easier. In addition, the loss of reflected light is small enough, and the handwriting is more natural and coordinated. Moreover, compared with the external touch panel, the total cost can be reduced from the user's perspective. In addition, it is possible to combine finger-based input with pen input based on electromagnetic induction (EMR), and high-precision handwriting can be achieved.

[0150] An example in which the liquid crystal display device 1 is used for an in-cell touch panel will be further described. Fig.13 1 is a schematic plan view illustrating the arrangement relationship between the touch sensor electrodes TX and the touch wirings TL included in the liquid crystal display device 1. Fig.13 As shown, the liquid crystal display device 1 includes a display region DR and a non-display region FR. The display region DR is composed of a plurality of pixels P arranged in a matrix (for example, Figure 3 The non-display region FR is located at the periphery of the display region DR and is also referred to as a peripheral region or a frame region.

[0151] 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. Fig.13 In the example shown, each touch sensor electrode TX is provided corresponding to two or more pixels P.

[0152] 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 the corresponding touch wiring TL. The 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.

[0153] The touch wiring TL is connected to a touch drive unit TD provided in the non-display region FR. The touch drive unit TD is configured to, for example, switch the plurality of touch sensor electrodes TX in a time-division manner between a display mode in which the plurality of touch sensor electrodes TX function as common electrodes CE and a touch detection mode in which the plurality of touch sensor electrodes TX function. For example, in the display mode, the touch drive 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 drive unit TD applies a touch drive signal to the touch sensor electrodes TX via the touch wiring TL.

[0154] Fig.13 In FIG. 5 , a plurality of touch wirings TL extend in a column direction (the same direction as the gate wiring SL). A portion of the touch wirings TL crosses another one or more touch sensor electrodes TX and extends to the corresponding touch sensor electrode TX.

[0155] If a certain touch sensor electrode TX is focused on, the first touch wiring TL1 for supplying a signal to the touch sensor electrode TX extends to the touch wiring contact portion TC, and the second touch wiring TL2 for supplying a signal to the other touch sensor electrode TX extends in a manner that crosses the touch sensor electrode TX. The second touch wiring TL2 overlaps the touch sensor electrode TX via an insulating layer. In addition, depending on the position of the touch sensor electrode TX, there are sometimes two or more touch wirings TL configured in a manner that crosses the touch sensor electrode TX, and sometimes there is no touch wiring TL that crosses the touch sensor electrode TX.

[0156] In the non-display region FR, in addition to the touch drive unit TD, a peripheral circuit (not shown) including a gate driver for supplying a gate signal to the gate bus (gate wiring) GL, a gate driver for supplying a gate signal to the gate bus (gate wiring) SL, and the like is provided. These drive circuits may also be mounted on, for example, the first substrate (TFT substrate) 10, or may be formed integrally (monolithically). A semiconductor chip including a part or all of the drive circuits may also be mounted on the non-display region FR.

[0157] In an in-cell touch panel, as TFT110, it is particularly preferred to use an In-Ga-Zn-O semiconductor. In addition, from the viewpoint of achieving flicker-free (also referred to as flicker-free), it is preferred to use a negative liquid crystal material. This is due to the following reasons. Positive liquid crystal materials often use materials with a large flexibility coefficient, and have a larger flexibility coefficient than negative liquid crystal materials. Therefore, in the lateral electric field method of the FFS mode using a positive liquid crystal material, when a voltage is applied, flexible polarization is spontaneously generated in the liquid crystal layer due to the influence of the fine slit electrodes on the electrodes (i.e., the fringe electric field). Since the liquid crystal responds according to the above-mentioned flexible polarization, it is believed that the brightness changes when the polarity is reversed, which can be easily regarded as flicker.

[0158] (Variation 1 of Implementation Example 1) In Embodiment 1, the structure in which the first electrode 121 as the lower electrode is the common electrode CE and the second electrode 122 as the upper electrode is the pixel electrode PE is described, but the second electrode 122 may be the common electrode CE and the first electrode 121 may be the pixel electrode PE in reverse. In this example, the second electrode 122 (upper electrode) is the common electrode CE and the first electrode 121 (lower electrode) is the pixel electrode PE (see Fig.14 ).

[0159] Fig.14 1 is a cross-sectional schematic diagram showing the liquid crystal display device 1 of this example in more detail. In this example, from the viewpoint of facilitating the generation of a lateral electric field, it is preferred that at least the upper electrode (the common electrode CE in this example) is a slit electrode. The lower electrode (the pixel electrode PE in this example) may be a planar electrode, i.e., a so-called solid electrode, or a slit electrode. The liquid crystal display device 1 involved in this example is particularly preferred as a relatively high-definition liquid crystal display device as described above, i.e., a liquid crystal display device having a relatively small area of ​​pixel P.

[0160] (Variation 2 of Implementation Example 1) In Embodiment 1, an FFS mode liquid crystal display device is described, but an IPS mode liquid crystal display device (wherein the liquid crystal layer 20 is twisted when no voltage is applied) may also be used. 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 preferably both the first electrode 121 and the second electrode 122 are slit electrodes.

[0161] (Implementation Method 2) In this embodiment, the features unique to this embodiment are mainly described, and the description of the contents repeated in the above-mentioned embodiment 1 is omitted. In the embodiment 1, the method in which only the second phase difference layer 42 includes one positive C plate is described, but in this embodiment, the method in which only the second phase difference layer 42 includes one positive C plate and the first phase difference layer 41 includes two positive C plates (the above-mentioned (ii)) is described. That is, except that the first phase difference layer 41 also includes two positive C plates, the rest is substantially the same as the embodiment 1.

[0162] Fig.15 FIG. 1 is a schematic cross-sectional view of a liquid crystal display device 1 according to an example of the present embodiment. Fig.15 As shown, the liquid crystal display device 1 includes a first polarizing plate 51, a first phase difference layer 41, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a second phase difference layer 42, and a second polarizing plate 52 in order from the back side to the observation side. The first phase difference layer 41 includes a positive C plate (also called a first positive C plate) 43 and a positive C plate (also called a second positive C plate) 45 in addition to a λ / 4 plate 411 and a λ / 2 plate 412, and the second phase difference layer 42 includes a λ / 4 plate 421, a λ / 2 plate 422, and a positive C plate (also called a first positive C plate) 44.

[0163] In the case where the first phase difference layer 41 includes the first positive C plate 43 and the second positive C plate 45 and the second phase difference layer 42 includes the positive C plate 44, the viewing angle characteristics are further improved compared with embodiment 1 and embodiment 3 described later. From the viewpoint of more fully exerting such an effect, it is preferred that the first positive C plates 43 and 44 are located between the λ / 4 plate and the λ / 2 plate, and it is also preferred that the second positive C plate 45 is located between the λ / 2 plate and the polarizing plate. In the present embodiment, the first phase difference layer 41 preferably includes the second positive C plate 45, the λ / 2 plate 412, the first positive C plate 43 and the λ / 4 plate 411 in sequence from the back side, and the second phase difference layer 42 preferably includes the λ / 4 plate 421, the positive C plate 44 and the λ / 2 plate 422 in sequence from the back side (refer to Fig.15 ).

[0164] The second positive C plate 45 (and 46 described later) may be the same as the first positive C plates 43 and 44 (same physical properties, same thickness, etc.) or different from the first positive C plates 43 and 44 as long as it satisfies "nz>nx≈ny". However, from the viewpoint of further exerting the effect of improving the viewing angle, the thickness direction phase difference Rth (absolute value) of the second positive C plates 45 and 46 is preferably 50 to 130 nm. It is more preferably 70 to 120 nm, and even more preferably 80 to 115 nm.

[0165] The thickness of each of the second positive C plates 45 (and 46) is preferably, for example, 0.1 to 100 μm. If it is within this range, the mechanical strength and display uniformity are more excellent. It is more preferably 0.1 to 80 μm, and further preferably 0.1 to 50 μm. In addition, when the positive C plates 45 and 46 have a stacked structure, it is preferred that the total thickness of the whole is set to the above range, and the thickness of each phase difference film may be the same or different.

[0166] (Implementation 3) In this embodiment, the features unique to this embodiment are mainly described, and the description of the contents repeated in the above-mentioned embodiments 1 and 2 is omitted. In this embodiment, the first phase difference layer 41 and the second phase difference layer 42 each include two positive C plates (the above (iii)) are described. In other words, in addition to including the positive C plate (also called the first positive C plate) 44, the second phase difference layer 42 also newly includes a positive C plate (also called the second positive C plate) 46. Except for the above, the other is substantially the same as the embodiment 2.

[0167] Fig.16 FIG. 1 is a schematic cross-sectional view of a liquid crystal display device 1 according to an example of the present embodiment. Fig.16 As shown, the liquid crystal display device 1 includes a first polarizing plate 51, a first retardation layer 41, a first substrate 10, a liquid crystal layer 20, a second substrate 30, a second retardation layer 42, and a second polarizing plate 52 in order from the back side to the observation side. The first retardation layer 41 includes a first positive C plate 43 and a second positive C plate 45 in addition to a λ / 4 plate 411 and a λ / 2 plate 412. The second retardation layer 42 includes a first positive C plate 44 and a second positive C plate 46 in addition to a λ / 4 plate 421 and a λ / 2 plate 422.

[0168] In the case where the first phase difference layer 41 includes the first positive C plate 43 and the second positive C plate 45 and the second phase difference layer 42 includes the first positive C plate 44 and the second positive C plate 46, the viewing angle characteristics are further improved compared to embodiment 1. From the viewpoint of giving full play to such an effect, it is preferred that the first positive C plates 43 and 44 are located between the λ / 4 plate and the λ / 2 plate as described above, and it is also preferred that the second positive C plates 45 and 46 are located between the λ / 2 plate and the polarizing plate. In the present embodiment, the first phase difference layer 41 preferably includes the second positive C plate 45, the λ / 2 plate 412, the first positive C plate 43, and the λ / 4 plate 411 in sequence from the back side, and the second phase difference layer 42 preferably includes the λ / 4 plate 421, the first positive C plate 44, the λ / 2 plate 422, and the second positive C plate 46 in sequence from the back side (refer to Fig.16 ).

[0169] (Implementation 4) In this embodiment, features unique to this embodiment are mainly described, and description of contents overlapping with those in Embodiment 1 is omitted. The liquid crystal display device of this embodiment differs from the liquid crystal display device of Embodiment 1 mainly in that a light source is provided on the observation side of the liquid crystal layer 20 .

[0170] Fig.17 2 is a schematic cross-sectional view of a liquid crystal display device 1 according to an example of the present embodiment. The liquid crystal display device 1 according to the present embodiment further includes a light source 62 (also referred to as a front light) on the observation side of the liquid crystal layer 20. Fig.17 As shown, the first polarizing plate 51, the first retardation layer 41, the first substrate 10, the liquid crystal layer 20, the second substrate 30, the second retardation layer 42, the second polarizing plate 52, and the light source 62 are provided in order from the back side to the observation side. In this embodiment, the first substrate 10 is preferably a TFT substrate.

[0171] The light source 62 (headlight) is not particularly limited as long as it is a structure that irradiates light. Specifically, for example, it is preferably a structure having a light source such as a light emitting diode (LED) and a light guide plate. The liquid crystal display device 1 also includes the light source 62, so that bright reflective display can be performed even in an environment where the ambient light cannot be fully obtained.

[0172] As mentioned above, although embodiment of this invention was described, each matter of description is all applicable to this invention as a whole.

[0173] The present invention is described in more detail by way of examples below, but the present invention is not limited to these examples. Hereinafter, absorption-type polarizing plates are used as polarizing plates 51 and 52. In addition, the applied voltage for white display is 5V, and the applied voltage for black display is 0V (i.e., no voltage is applied).

[0174] (Trial Example 1) The test unit 1000 was prototyped as follows. First, the liquid crystal unit 1100 used to obtain the test unit 1000 is as follows: Fig.18B The invention is shown as comprising a first substrate 10, a second substrate 30, and a liquid crystal layer 20 disposed between these substrates. Fig.18A 1 is a schematic plan view showing the structure of the liquid crystal cell 1100 when viewed from the front. Fig.18B Yes Fig.18A The AA line in is a cross-sectional schematic diagram of the cutting surface (AA line cross-sectional view).

[0175] like Fig.18BAs shown, the first substrate 10 has a glass substrate 100, on which a common electrode CE as a first electrode 121, a dielectric layer 153, a pixel electrode PE as a second electrode 122, and a first horizontal alignment film 140 are sequentially provided. The common electrode CE is formed of ITO, and the thickness of the common electrode CE is 100nm. The dielectric layer 153 is formed of silicon nitride (SiNx), and the thickness of the dielectric layer 153 is 300nm. The pixel electrode PE is formed of ITO, and the thickness of the pixel electrode PE is 100nm. The pixel electrode PE has a plurality of strip portions SP and a plurality of slits Sl. The width of each strip portion SP is 3μm, and the width of each slit Sl (the interval between two adjacent strip portions SP) is 5μm. Each strip portion SP is bent in a く-shaped shape. That is, each strip portion SP includes a first portion SPa extending in a certain direction (first direction) and a second portion SPb extending in a direction different from the first direction (second direction). Flexion angle (the first part SPa and the second part SPb of the strip SP are respectively relative to Fig.18A The angle formed by the left and right directions in the image is 7°.

[0176] The second substrate 30 is Fig.18B The glass substrate 300 and the second horizontal alignment film 340 disposed on the glass substrate 300 are shown.

[0177] The thickness (cell gap) of the liquid crystal layer 20 is defined by plastic beads (not shown).

[0178] The alignment treatment of the first horizontal alignment film 140 and the second horizontal alignment film 340 is performed by a photo-alignment treatment or a rubbing treatment.

[0179] When using photo-alignment treatment, a photo-decomposable photo-alignment film material is used. The photo-alignment film material is applied by spin coating, and the thickness of the alignment film is (i.e. 100nm). The non-polarized UV light emitted from the UV lamp unit is converted into polarized UV light by a wire grid polarizer, and the polarized UV light is irradiated to the alignment film, thereby performing a photo-alignment treatment. The extinction ratio of the wire grid polarizer is 100:1. The wavelength of UV light effective for photo-alignment is 220 to 260nm, and the irradiation energy is 300mJ / cm 2 The orientation direction of the liquid crystal molecules is a direction substantially orthogonal to the transmission axis direction of the polarized UV light (particularly preferably a 90° direction).

[0180] In the case of using friction treatment, a horizontal alignment film is formed, and the friction treatment is performed using a friction roller (e.g., a roller wrapped with a cloth), thereby performing an alignment treatment. Thus, a uniaxial alignment orientation of the liquid crystal molecules is obtained. As an alignment film material suitable for causing the liquid crystal molecules to move under a transverse electric field, a polyimide-based material is preferred. In addition, a material that does not produce pre-tilt due to the friction treatment is preferred, and the material is commercially available. The liquid crystal molecules are oriented approximately parallel to the rubbing direction.

[0181] For the liquid crystal cell 1100 having the above structure, the retardation of the liquid crystal layer 20 was first measured using a polarimeter ("AxoScan" manufactured by Axometrics), and then the cell thickness was measured using a cell gap tester ("RetsQC" manufactured by Otsuka Electronics Co., Ltd.).

[0182] Then, if Fig.19A As shown, the λ / 4 plate 421, the λ / 2 plate 422, and the polarizing plate 52 are sequentially attached to the second substrate 30 side of the liquid crystal cell 1100 (the adhesive layer is not shown). Thereafter, during reflection observation, one drop of matching oil mo for reducing the loss caused by interface reflection is dripped on the reflective layer 130 having a concave-convex surface structure (MRS), and the liquid crystal cell 1100 is set on the reflective layer 130 in such a manner that the first substrate 10 side is at the bottom, and verification is performed (this corresponds to the test cell 1000 during reflection observation). During transmission observation, the λ / 4 plate 411, the λ / 2 plate 412, and the polarizing plate 51 are sequentially attached to the first substrate 10 side of the liquid crystal cell 1100, and verification is performed (this corresponds to the test cell 1000 during transmission observation). In this way, the test cell 1000 is manufactured. In addition, "NPF-CRT1794KDUHC3" manufactured by Nitto Denko Corporation was used as the polarizing plates 51 and 52, "NZF-UF 01A" (retardation: 140 nm) manufactured by Nitto Denko Corporation was used as the λ / 4 plates 411 and 421, and "NZF-UF 01A" (retardation: 270 nm) manufactured by Nitto Denko Corporation was used as the λ / 2 plates 412 and 422.

[0183] In addition, in this state, the voltage applied between the pixel electrode PE and the common electrode CE is changed to measure the reflectivity. A function generator ("AFG1022" manufactured by TEKTRONIX) capable of applying a voltage of 0V to 10V at a rectangular wave of 30Hz is used to apply the voltage to the pixel electrode PE and the common electrode CE. Unless otherwise specified, a spectrophotometer ("CM-2600d" manufactured by MINOLTA) is used to measure the reflectivity. Fig.19A is a schematic cross-sectional view of the test unit 1000 .

[0184] (Verification Example 1) In this verification example, the following (a) and (b) were studied using the test unit 1000. The twist angle was 83° and a negative liquid crystal material was used. The optical axis setting (initial setting) and specifications of this verification example are shown in Table 5 and Fig.10 shown. Fig.10 1 is a diagram conceptually showing the optical axis setting of the test unit 1000. In this verification example, the study was conducted using the test unit 1000 without a positive C plate, but the same tendency was obtained when a positive C plate was provided.

[0185] [Table 5]

[0186] (a) Relationship between the axis setting of the optical film and the transmission mode efficiency and transmission contrast ratio For the test unit 1000, the relationship between the axis setting of the optical film on the back side and the transmission mode efficiency and transmission contrast ratio was studied. Fig. 20 as well as Fig.21 shown. Fig. 20 as well as Fig.21 2 is a diagram showing the results of Verification Example 1.

[0187] Fig. 20 Each graph is a graph of the transmission mode efficiency and the transmission contrast measured by rotating only the first phase difference layer 41 (i.e., the first λ / 2 plate 412 and the first λ / 4 plate 411). The first phase difference layer 41 is rotated within a range of ±10° from the optimal value of the axis setting obtained by the above (II) (refer to Table 4). The axis angle of the polarizing plate 51 is fixed to the initial setting. The angle formed by the slow axis 412SA of the λ / 2 plate 412 and the slow axis 411SA of the λ / 4 plate 411 is fixed, and the λ / 2 plate 412 and the λ / 4 plate 411 are rotated as a group. The horizontal axis is the angle in the direction of the slow axis 411SA of the λ / 4 plate 411, and the vertical axis is the transmission mode efficiency or the transmission contrast.

[0188] Fig.21 Each of the graphs is a graph in which only the first polarizing plate 51 is rotated and the transmission mode efficiency and transmission contrast are measured. The polarizing plate 51 is rotated within a range of ±10° from the optimal value of the axis setting obtained by the above (II) (refer to Table 4). The axis angle of the first phase difference layer 41 is fixed to the initial setting. The horizontal axis is the angle of the polarization axis 51AA direction of the polarizing plate 51, and the vertical axis is the transmission mode efficiency or transmission contrast.

[0189] Fig. 20 as well as Fig.21In the "0V" column, a graph showing the transmission mode efficiency of a black display is recorded. A graph showing the transmission mode efficiency of a white display is recorded in the "5V" column. The transmission mode efficiency of each display is calculated using the above formula (1). Based on the transmission mode efficiency of each display measured in this way, the transmission contrast ratio is calculated. That is, the transmission contrast is calculated according to the following formula (2): Transmission contrast ratio = transmission mode efficiency of white display / transmission mode efficiency of black display. Approximate curves are also plotted in each graph in the "0 V" column.

[0190] Fig. 20 In the figure, when the slow axis 411SA direction of the λ / 4 plate 411 is -71.4°, the slow axis 412SA direction of the λ / 2 plate 412 is 50.4°. Fig. 20 and Fig.21 It can be seen that the axis settings for the minimum transmission mode efficiency and maximum transmission contrast for black display are: the slow axis 411SA of the λ / 4 plate 411 is -71.4°, the slow axis 412SA of the λ / 2 plate 412 is 50.4°, and the polarization axis 51AA direction of the polarizing plate 51 is 38.0°. The slow axis 411SA of the λ / 4 plate 411 and the slow axis 412SA of the λ / 2 plate 412 correspond to the optimal values ​​of the axis settings obtained in (II) above (see Table 4).

[0191] (b) Relationship between axis setting of optical film and chromaticity For test unit 1000, the relationship between the axis setting of the optical film on the back side and the chromaticity of white display was studied. The chromaticity was evaluated using an xy chromaticity diagram. For reference, the chromaticity of the D65 light source (x=0.3127, y=0.3290) was plotted in each figure. The results are shown in Figure 1. Fig. 22 as well as Fig.23 shown. Fig. 22 as well as Fig.23 2 is a diagram showing the results of Verification Example 1.

[0192] Fig. 22 The graph is a graph of the chromaticity measured by rotating only the first phase difference layer 41 (i.e., the first λ / 2 plate 412 and the first λ / 4 plate 411). The first phase difference layer 41 is rotated within a range of ±10° from the optimal value of the axis setting obtained by the above (II) (see Table 4). The axis angle of the polarizing plate 51 is fixed to the initial setting. The angle between the slow axis 412SA of the λ / 2 plate 412 and the slow axis 411SA of the λ / 4 plate 411 is fixed, and the λ / 2 plate 412 and the λ / 4 plate 411 are rotated as a group.

[0193] Fig.23The graph is a graph obtained by measuring the chromaticity by rotating only the first polarizing plate 51. The polarizing plate 51 was rotated within a range of ±10° from the optimal value of the axis setting obtained by (II) above (see Table 4). The axis angle of the first phase difference layer 41 was fixed to the initial setting.

[0194] from Fig. 22 and Fig.23 It can be seen that the optimal axis settings of the back optical film are: the slow axis 411SA of the λ / 4 plate 411 is -71.4°, the slow axis 412SA of the λ / 2 plate 412 is 50.4°, and the polarization axis 51AA direction of the polarizer 51 is 38.0°. It is believed that if the axis settings are such, the chromaticity almost the same as that of the D65 light source can be obtained by adjusting the hue (yellow shift) of the light source (backlight source 61 in this verification example) and adjusting the color of the color filter.

[0195] (Trial Example 2) In the production process of the above-mentioned test unit 1000, except for changing the process of pasting the optical film on the first substrate 10 side of the liquid crystal unit 1100 to the process of sequentially pasting the λ / 4 plate 411, the positive C plate 43, the λ / 2 plate 412 and the polarizing plate 51 on the first substrate 10 side of the liquid crystal unit 1100, the test unit 2000 is produced in the same manner as the production method of the above-mentioned test unit 1000.

[0196] (Trial Example 3) In the production process of the above-mentioned test unit 1000, except for changing the process of pasting the optical film on the first substrate 10 side of the liquid crystal unit 1100 to the process of sequentially pasting the λ / 4 plate 411, the first positive C plate 43, the λ / 2 plate 412, the second positive C plate 45 and the polarizing plate 51 on the first substrate 10 side of the liquid crystal unit 1100, the test unit 3000 is produced in the same manner as the production method of the above-mentioned test unit 1000.

[0197] (Trial Example 4) In the production process of the above-mentioned test unit 1000, except for changing the process of pasting the optical film on the second substrate 30 side of the liquid crystal unit 1100 to the process of sequentially pasting the λ / 4 plate 421, the positive C plate 44, the λ / 2 plate 422 and the polarizing plate 52 on the second substrate 30 side of the liquid crystal unit 1100, the test unit 4000 is produced in the same manner as the production method of the above-mentioned test unit 1000.

[0198] (Trial Example 5) In the production process of the above-mentioned test unit 1000, except for changing the process of pasting the optical film on the liquid crystal unit 1100 to the process of pasting the λ / 4 plate 411, the positive C plate 43, the λ / 2 plate 412 and the polarizing plate 51 in sequence on the first substrate 10 side of the liquid crystal unit 1100 and pasting the λ / 4 plate 421, the positive C plate 44, the λ / 2 plate 422 and the polarizing plate 52 in sequence on the second substrate 30 side of the liquid crystal unit 1100, the test unit 5000 is produced in the same manner as the production method of the above-mentioned test unit 1000.

[0199] (Trial Example 6) In the production process of the above-mentioned test unit 1000, except for changing the process of pasting the optical film on the liquid crystal unit 1100 to the process of pasting the λ / 4 plate 411, the first positive C plate 43, the λ / 2 plate 412, the second positive C plate 45 and the polarizing plate 51 in sequence on the first substrate 10 side of the liquid crystal unit 1100, and pasting the λ / 4 plate 421, the positive C plate 44, the λ / 2 plate 422 and the polarizing plate 52 in sequence on the second substrate 30 side of the liquid crystal unit 1100, the test unit 6000 is produced in the same manner as the production method of the above-mentioned test unit 1000.

[0200] (Trial Example 7) In the production process of the above-mentioned test unit 1000, except for changing the process of pasting the optical film on the second substrate 30 side of the liquid crystal unit 1100 to the process of pasting the λ / 4 plate 421, the first positive C plate 44, the λ / 2 plate 422, the second positive C plate 46 and the polarizing plate 52 in sequence, the test unit 7000 is produced in the same manner as the production method of the above-mentioned test unit 1000.

[0201] (Trial Example 8) In the production process of the above-mentioned test unit 1000, except for changing the process of pasting the optical film on the liquid crystal unit 1100 to the process of pasting the λ / 4 plate 411, the positive C plate 43, the λ / 2 plate 412 and the polarizing plate 51 in sequence on the first substrate 10 side of the liquid crystal unit 1100 and pasting the λ / 4 plate 421, the first positive C plate 44, the λ / 2 plate 422, the second positive C plate 46 and the polarizing plate 52 in sequence on the second substrate 30 side of the liquid crystal unit 1100, the test unit 8000 is produced in the same manner as the production method of the above-mentioned test unit 1000.

[0202] (Trial Example 9) In the production process of the above-mentioned test unit 1000, except for changing the process of pasting the optical film on the liquid crystal unit 1100 to the process of pasting the λ / 4 plate 421, the first positive C plate 44, the λ / 2 plate 422, the second positive C plate 45 and the polarizing plate 52 in sequence, and pasting the λ / 4 plate 421, the first positive C plate 44, the λ / 2 plate 422, the second positive C plate 46 and the polarizing plate 52 in sequence on the second substrate 30 side of the liquid crystal unit 1100, the test unit 9000 is produced in the same manner as the production method of the above-mentioned test unit 1000.

[0203] In Prototype Examples 2 to 9, films with Rth of 200 nm were used as the positive C plates 43 and 44 disposed between the λ / 4 plate and the λ / 2 plate, and films with Rth of 115 nm were used as the positive C plates 45 and 46 disposed between the λ / 2 plate and the polarizing plate. FIG. 19B to FIG. 19I . The layer structures of the test cells obtained in Prototype Examples 2 to 9 are shown in FIG. FIG. 19B to FIG. 19I It is a schematic cross-sectional view showing the layer structure of each test cell obtained in Prototype Examples 2 to 9.

[0204] (Verification Example 2) In this verification example, the following (c) to (d) were performed using test units 1000 to 9000, respectively. (f) The twist angle is 83° and a negative liquid crystal material is used. The optical axis setting (initial setting) of this verification example is shown in Table 5 and Figure 24 to Figure 26 shown. Fig.24 4 is a diagram conceptually showing the optical axis setting in an example using the test unit 4000 , which corresponds to the most preferable optical axis setting in the first embodiment described above. Fig.25 1 is a diagram conceptually showing the optical axis setting in an example using the test unit 6000 , which corresponds to the most preferable optical axis setting in the above-mentioned second embodiment. Fig.26 1 is a diagram conceptually showing the optical axis setting in an example using the test unit 9000 , which corresponds to the most preferable optical axis setting in the third embodiment described above.

[0205] (c) Front contrast and viewing angle characteristics of white display in reflection mode For each of the test units 1000, 4000 and 9000, the front contrast (also called front CR) and the viewing angle characteristics of white display were measured. Thereafter, evaluation was performed based on the following criteria. The results are shown in Table 6.

[0206] (Front contrast) The ratio of the reflectivity at 5 V to the reflectivity at 0 V in the reflection mode (5 V / 0 V) was determined. The values ​​are shown in Table 6. Based on the values, the following criteria were used for evaluation. ○ (Very good): The above ratio is 30 or more. × (Poor): The above ratio is less than 30.

[0207] (Viewing angle characteristics) When the white display is in the reflection mode, the azimuth angle is changed in the range of 0° to 345° in 15° steps, and the polar angle is changed in the range of 0° to 60° in 10° steps to measure the reflectivity (absolute value). Then, the viewing angle characteristics are evaluated according to the following criteria for a total of 8 directions, namely, the 4 directions of up, down, left, and right, and the 4 directions of diagonal. In addition, the 3 o'clock direction of the clock is 0°, the top is 90°, the bottom is 270°, the left is 180°, and the right is 0°. In addition, the inclined directions are 45°, 135°, 225°, and 315°. The results are shown in Table 6. ○ (Very good): The reflectivity difference (maximum reflectivity - minimum reflectivity) at a polar angle of 60° is less than 2%. Δ (Good): The reflectivity difference is 2% or more and less than 5%. × (Poor): The reflectivity difference is 5% or more.

[0208] [Table 6]

[0209] According to Table 6, in the reflective display, the front contrast ratio is higher in Example 2-4 using the test unit 4000 than in Example 2-1 using the test unit 1000, and the front contrast ratio is even higher in Example 2-9. It can be seen that the viewing angle characteristics are also better in Examples 2-4 and 2-9 than in Example 2-1.

[0210] (d) Contrast (CR) characteristics of white display in transmission mode The contrast characteristics of white display were measured for each of the test units 1000 to 9000. Specifically, in the transmission mode, the luminance (absolute value) was measured with the azimuth angle in the range of 0° to 359° and the polar angle in the range of 0° to 88°, and then the following criteria were used to evaluate the azimuth symmetry of the transmission contrast in this example compared with the azimuth symmetry of the transmission contrast in Example 2-1 using the test unit 1000. In addition, the azimuth of the clock is 0° for each direction, 90° for the top, 270° for the bottom, 180° for the left, and 0° for the right. In addition, the oblique directions are 45°, 135°, 225°, and 315°. The "EZContrast" produced by ELDIM was used for the measurement. The results are shown in Tables 7 to 9. Tables 7 to 9 also show the front contrast ratio value. ◎(Excellent): The best. 0(Very good): Very good. ×(Poor): Same or poor.

[0211] [Table 7]

[0212] [Table 8]

[0213] [Table 9]

[0214] As can be seen from Tables 7 to 9, in the transmissive display, the contrast characteristics are better in Examples 2-2, 2-4, 2-5, 2-6, 2-7, 2-8, and 2-9 than in Example 2-1 using the test unit 1000. Among these, Examples 2-4, 2-6, and 2-9 are better, and Example 2-6 is the best.

[0215] (e) Change of white brightness in transmissive mode For each of the test units 1000 to 9000, the brightness changes in the vertical, horizontal, and oblique directions were evaluated. Specifically, in the white display in the transmission mode, the brightness difference (maximum brightness - minimum brightness) at a polar angle of 60° was evaluated according to the following criteria. The results are shown in Tables 10 to 12. ○ (Very good): The brightness difference at a polar angle of 60° is less than 100 cd / m 2 . △(Good): The difference in brightness is 100cd / m 2 Above and less than 200cd / m 2 . ×(Poor): The difference in brightness is 200cd / m 2 above.

[0216] [Table 10]

[0217] [Table 11]

[0218] [Table 12]

[0219] As can be seen from Tables 10 to 12, in the transmissive display, the brightness changes in Examples 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, and 2-9 are small and good compared to Example 2-1 using the test unit 1000. Among them, Examples 2-4, 2-6, and 2-9 are better, and Examples 2-6 and 2-9 are the best. In Examples 2-6 and 2-9, the brightness changes in the up-down, left-right, and oblique directions are symmetrical.

[0220] (f) Changes in black brightness in transmissive mode For each of the test units 1000 to 9000, the brightness changes in the up, down, left, right, and tilt directions were evaluated. Specifically, in the black display of the transmission mode, the difference in brightness between the front (polar angle 0°) and the polar angle 60° at each azimuth angle (polar angle 60°-front (polar angle 0°)) was defined as the black tone prominence of the oblique view, and the evaluation was performed according to the following criteria. The results are shown in Tables 13 to 15. ○ (Very good): The difference in brightness between the front view (polar angle 0°) and the polar angle 60° is less than 50 cd / m 2 . △(Good): The difference in brightness is 50cd / m 2 Above and less than 110cd / m 2 . ×(Poor): The difference in brightness is 110cd / m 2 above.

[0221] [Table 13]

[0222] [Table 14]

[0223] [Table 15]

[0224] As can be seen from Tables 13 to 15, in the transmissive display, compared with Example 2-1 using the test unit 1000, in Example 2-2, Example 2-4, Example 2-5, Example 2-6, Example 2-7, Example 2-8, and Example 2-9, black tone protrusion is small and good. Among them, Example 2-4, Example 2-6, and Example 2-9 are better, and Example 2-6 and Example 2-9 are the best. In Example 2-6 and Example 2-9, black tone protrusion is small and good in the vertical, horizontal, and oblique directions.

[0225] (Verification Example 3) In this verification example, the viewing angle characteristics were studied in more detail using test units 1000, 4000, 6000 and 9000. Specifically, the following studies (g) to (p) were conducted. The twist angle was 83° and a negative liquid crystal material was used. The optical axis settings (initial settings) of this verification example are shown in Table 5 and Figure 24 to Figure 26 shown. In addition, in the following (g) to (k), when the test unit 6000 is used (Example 3-6), the same results as those of Example 3-4 using the test unit 4000 are obtained, and therefore the results of Example 3-4 are omitted.

[0226] (g) Viewing angle characteristics of white display in reflective mode For each test unit, the "Display Measuring System" (model: DMS 803) produced by Instrument Systems was used to measure the distribution of the reflectance of the white display in reflective mode. The orientation in the reflectance characteristic graph is 0° at 3 o'clock on the clock, 90° at the top, 270° at the bottom, 180° at the left, 0° at the right, and 45°, 135°, 225°, and 315° at the tilt directions. In addition, the reflectance characteristics are also plotted in graphs for the orientation with the widest distribution of reflectance (also called orientation I) and the narrowest orientation (also called orientation II). The results are as follows: FIG. 27A to FIG. 27C shown. FIG. 27A to FIG. 27C 2 is a diagram showing the results of Verification Example 3.

[0227] If the white reflectance distribution diagrams in each figure are compared, it can be seen that in Example 3-9, the distribution diagram is closest to a circle, so the viewing angle characteristics when displaying white are the best. In addition, in Example 3-1, the orientation I is 210° and the orientation II is 120°, in Example 3-4, the orientation I is 90° and the orientation II is 180°, and in Example 3-9, the orientation I is 135° and the orientation II is 30°.

[0228] As can be seen from the various graphs of white reflectance, in Examples 3-4 and 3-9, there is no difference in reflectance between the upper and lower directions, nor between the left and right directions, whereas in Example 3-1, there is a difference in reflectance between the upper and lower directions, as well as between the left and right directions. It can be seen that compared with Example 3-1, the difference in reflectance in the oblique direction is smaller in Example 3-4, and there is no difference in reflectance in the oblique direction in Example 3-9. It can be seen that compared with Example 3-1, the difference in reflectance between the widest distribution direction and the narrowest distribution direction is smaller in Examples 3-4 and 3-9.

[0229] Therefore, it can be seen that Example 3-9 is the best in terms of the viewing angle characteristics of white display, Example 3-4 (and Example 3-6) are also good, and on the other hand, Example 3-1 is poor.

[0230] (h) Viewing angle characteristics of black display in reflective mode For each test unit, the "Display Measuring System" (model: DMS 803) produced by Instrument Systems was used to measure the distribution of the reflectivity of the black display. The orientation in the reflectivity characteristics chart is 0° at 3 o'clock on the clock, 90° at the top, 270° at the bottom, 180° at the left, 0° at the right, and 45°, 135°, 225°, and 315° at the tilt directions. In addition, the reflectivity characteristics are also plotted in charts for orientation I, where the reflectivity distribution is the widest, and orientation II, where the reflectivity distribution is the narrowest. The results are shown in the figure below. FIG. 28A to FIG. 28C shown. FIG. 28A to FIG. 28C 2 is a diagram showing the results of Verification Example 3.

[0231] According to the black reflectivity distribution diagrams in each figure, in Example 3-1, orientation I is 210°, orientation II is 120°, in Example 3-4, orientation I is 90°, orientation II is 180°, and in Example 3-9, orientation I is 135°, orientation II is 30°. In addition, the shape of the reflectivity distribution can ensure symmetry in the upper and lower directions and in the left and right directions by changing the direction of the initial orientation of the liquid crystal molecules.

[0232] As can be seen from the graphs of black reflectance, in any of Examples 3-1, 3-4, and 3-9, there is no difference in reflectance between the upper and lower directions, nor between the left and right directions. On the other hand, it can be seen that the difference in reflectance in the oblique direction is larger in Example 3-1, while it is smaller in Examples 3-4 and 3-9. It can be seen that the difference in reflectance between direction I and direction II is smaller in Example 3-9 than in Example 3-1.

[0233] Therefore, it can be seen that Example 3-9 is the best in terms of the viewing angle characteristics of black display, Example 3-4 (and Example 3-6) are also good, and on the other hand, Example 3-1 is poor.

[0234] (i) Contrast characteristics in reflection mode For each test unit, the distribution of contrast in the reflective mode is calculated based on the viewing angle characteristics of the white display and the viewing angle characteristics of the black display. Specifically, the reflectance ratio (reflectance of the white display / reflectance of the black display) is calculated at each azimuth and polar angle. The azimuth is such that the 3 o'clock direction of the clock is 0°, the top is 90°, the bottom is 270°, the left is 180°, the right is 0°, and the tilt directions are 45°, 135°, 225°, and 315°. The results are as follows: FIG. 29A to FIG. 29C shown. FIG. 29A to FIG. 29C 2 is a diagram showing the results of Verification Example 3.

[0235] according to FIG. 29A to FIG. 29C It can be seen that, for the contrast characteristics in the reflection mode, Example 3-9 is the best, Example 3-4 (and Example 3-5) are also good, while Example 3-1 is poor. In addition, the shape of the contrast distribution can ensure vertical and horizontal symmetry by changing the direction of the initial orientation of the liquid crystal molecules.

[0236] (j) Field of view characteristics in reflection mode (oblique γ characteristics) For each test unit, the "Display Measuring System" (model: DMS 803) produced by Instrument Systems was used to measure the distribution diagram of the reflection brightness from the grayscale level 255 of the white display to the grayscale level 0 of the black display at every 32 levels. As a representative example, the distribution diagram of the reflection brightness at the grayscale level 255 of the white display is shown. The γ curve is calculated based on the results of the predetermined grayscales (255, 224, 192, 160, 128, 96, 64, 32, 0). Based on the obtained distribution diagram, the orientation (also called orientation III) with a higher grayscale than the front side (γ=2.2) and the orientation (also called orientation IV) with a lower grayscale than the front side (γ=2.2) or showing a special characteristic are obtained, and the γ curve is analyzed with a polar angle of 50° in these orientations. For the graph of the oblique γ characteristic, the horizontal axis is the grayscale (0 to 255 levels) when viewed directly, and the vertical axis is the standardized reflectance. Correct the front side to γ ​​= 2.2. The result is as follows FIG. 30A to FIG. 30C shown. FIG. 30A to FIG. 30C 2 is a diagram showing the results of Verification Example 3.

[0237] According to the white brightness distribution diagram in each figure, in Example 3-1, the azimuth III is 210° and the azimuth IV is 120°, in Example 3-4, the azimuth III is 90° and the azimuth IV is 180°, and in Example 3-9, the azimuth III is 135° and the azimuth IV is 30°. Each angle shows the angle of the azimuth direction when the 3 o'clock direction of the clock is 0°.

[0238] (k) Field of view characteristics in reflection mode (image simulation) Implemented according to FIG. 30A to FIG. 30C Specifically, the original color image is made into a normal image (also called the original image), and the original image is converted according to the γ curve of each azimuth angle and polar angle of 50°. The result is as follows FIG. 30A to FIG. 30C For comparison, Fig.31 An image of the front view is shown.

[0239] according to FIG. 30A to FIG. 30C It can be seen that, for the display quality of the image at a squinting angle, Example 3-9 is the best, Example 3-4 (and Example 3-6) are also good, while Example 3-1 is relatively poor. In addition, from the viewpoint of film cost and production yield, Example 3-4 (and Example 3-6) using the test unit 4000 is the most effective.

[0240] (l) Viewing angle characteristics of white display in transmission mode For each test unit, the "EZContrast" produced by ELDIM was used to measure the distribution of the transmission brightness of the white display at a grayscale level of 255. The azimuth in the brightness characteristic graph is 0° at 3 o'clock on the clock, 90° at the top, 270° at the bottom, 180° at the left, 0° at the right, and 45°, 135°, 225°, and 315° at the tilt directions. In addition, the brightness characteristics are also plotted in graphs for the widest distribution of white brightness, azimuth I, and the narrowest distribution, azimuth II. The results are shown in the figure below. FIG. 32A to FIG. 32D shown. FIG. 32A to FIG. 32D 2 is a diagram showing the results of Verification Example 3.

[0241] According to the white brightness distribution diagrams in each figure, in Example 3-1, the orientation I is 30° and the orientation II is 300°, in Example 3-4, the orientation I is 225° and the orientation II is 315°, in Example 3-9, the orientation I is 150° and the orientation II is 240°, and in Example 3-6, the orientation I is 180° and the orientation II is 90°. In each distribution diagram, the value in the center is 500 or more.

[0242] according to FIG. 32A to FIG. 32DIt can be seen that, for the viewing angle characteristics of white display in the transmission mode, Example 3-6 is the best, Example 3-9 is the second best, Example 3-4 is the third best, and on the other hand, Example 3-1 is poor. From the perspective of film cost and production yield, Example 3-4 using the test unit 4000 is the most effective.

[0243] (m) Viewing angle characteristics of black display in transmission mode For each test unit, the distribution diagram of the transmission brightness at grayscale level 0 of the black display was measured using "EZContrast" produced by ELDIM. The azimuth in the chart of brightness characteristics is 0° at 3 o'clock, 90° at the top, 270° at the bottom, 180° at the left, 0° at the right, and 45°, 135°, 225°, and 315° at the tilt directions. In addition, the brightness characteristics are also plotted in charts for the widest distribution of black brightness, direction I, and the narrowest distribution, direction II. The results are shown in Figure 1. FIG. 33A to FIG. 33D shown. FIG. 33A to FIG. 33D 2 is a diagram showing the results of Verification Example 3.

[0244] According to the black brightness distribution diagrams in each figure, in Example 3-1, the orientation I is 30° and the orientation II is 300°, in Example 3-4, the orientation I is 225° and the orientation II is 315°, in Example 3-9, the orientation I is 150° and the orientation II is 240°, and in Example 3-6, the orientation I is 180° and the orientation II is 90°. In each distribution diagram, the value in the center is 50 or more.

[0245] according to FIG. 33A to FIG. 33D It can be seen that, for the viewing angle characteristics of black display in the transmission mode, Example 3-6 is the best, Example 3-9 is the second best, Example 3-4 is the third best, while Example 3-1 is poor. From the perspective of film cost and production yield, Example 3-4 using the test unit 4000 is the most effective.

[0246] (n) Contrast characteristics in transmission mode For each test unit, the distribution of contrast in the transmission mode is calculated based on the white brightness distribution diagram and the black brightness distribution diagram. Specifically, the brightness ratio (brightness of white display / brightness of black display) is calculated at each azimuth angle and polar angle. The azimuth in the brightness characteristic diagram is 0° at 3 o'clock on the clock, 90° at the top, 270° at the bottom, 180° at the left, 0° at the right, and 45°, 135°, 225°, and 315° at the tilt directions. The results are as follows: FIG. 34A to FIG. 34D shown. FIG. 34A to FIG. 34D 2 is a diagram showing the results of Verification Example 3.

[0247] according to FIG. 34A to FIG. 34DIt can be seen that, in terms of contrast characteristics in the transmission mode, Example 3-6 is the best, Example 3-9 is the second best, Example 3-4 is the third best, and on the other hand, Example 3-1 is poor. Example 3-6 has the best viewing angle balance in the vertical and horizontal directions. In addition, in each contrast distribution diagram, the value of the center is 50 or more.

[0248] (o) Viewing angle characteristics in transmission mode (oblique γ characteristics) For each test unit, "EZContrast" produced by ELDIM was used to measure the distribution of the transmitted brightness from grayscale level 255 for white display to grayscale level 0 for black display at every 32 levels. As a representative example, a distribution diagram of the transmitted brightness at grayscale level 255 for white display is shown. The γ curve is calculated based on the results of the predetermined grayscales (255, 224, 192, 160, 128, 96, 64, 32, 0). Based on the obtained distribution diagram, orientation III with a higher grayscale than the front side (γ=2.2) and orientation IV with a lower grayscale than the front side (γ=2.2) or showing peculiar characteristics are obtained, and in these orientations, the γ curve is analyzed with a polar angle of 50°. For the graph of the oblique γ characteristic, the horizontal axis is the grayscale (0 to 255 levels) when viewed directly, and the vertical axis is the standardized brightness. The front side is corrected to γ=2.2. The results are as follows. FIG. 35A to FIG. 35D shown. FIG. 35A to FIG. 35D 2 is a diagram showing the results of Verification Example 3.

[0249] According to the white brightness distribution diagram in each figure, in Example 3-1, the azimuth III is 30° and the azimuth IV is 300°, in Example 3-4, the azimuth III is 225° and the azimuth IV is 315°, in Example 3-9, the azimuth III is 150° and the azimuth IV is 240°, and in Example 3-6, the azimuth III is 180° and the azimuth IV is 90°. Each angle shows the angle of the azimuth direction when the 3 o'clock direction of the clock is 0°.

[0250] (p) Field of view characteristics in reflection mode (image simulation) Implemented according to FIG. 35A to FIG. 35D Specifically, the original color image is made into a normal image (also called the original image), and the original image is converted according to the γ curve of each azimuth angle and polar angle of 50°. The result is as follows FIG. 35A to FIG. 35D For comparison, Fig.31 An image of the front view is shown.

[0251] according to FIG. 35A to FIG. 35DIt can be seen that the display quality of the image at an oblique view is the best in Example 3-6, the second best in Example 3-9, the third best in Example 3-4, and the poor in Example 3-1. From the viewpoint of film cost and production yield, Example 3-4 using the test unit 4000 is the most effective.

[0252] The various aspects of the present invention described above may be appropriately combined within the scope not departing from the gist of the present invention. Description of Reference Numerals

[0253] 1...semi-reflective liquid crystal display device; 1T...transmissive liquid crystal display device; 1R...reflective liquid crystal display device; 1X...liquid crystal panel; 10, 30...substrate; 20...liquid crystal layer; 21, 21A, 21B...liquid crystal molecules; 41, 42...phase difference layer; 411, 421...λ / 4 plate; 412, 422...λ / 2 plate; 411SA, 421SA, 412SA, 422SA...in-plane slow axis; 43, 44, 45, 46...positive C plate; 51, 52...polarizing plate; 51AA, 52AA...polarizing axis; 61, 62...light source; 100, 300: supporting substrate; 110...TFT; 121, 122...electrode; 130...reflective layer; 140, 340...horizontal alignment film; 151, 152...interlayer insulating layer; 153...dielectric layer; 160...contact electrode; 310...color filter layer; 1000, 2000, 3000, 4000, 5000, 6000, 7000, 80 00, 9000...test unit; 1100...liquid crystal unit; BP...backplane circuit; CE...common electrode; PE...pixel electrode; CH1, CH2...contact hole; DR...display area; FR...non-display area; GL...gate wiring; SL...gate wiring; p...convex portion; P...pixel; Rf...reflective area; Tr...transmissive area; Sl...slit; SP, SPa, SPb...strip portion; TC...touch wiring contact portion; TD...touch drive portion; TL, TL1, TL2...touch wiring; TX...touch sensor electrode.

Claims

1. A semi-transmissive liquid crystal display device having a plurality of pixels, characterized in that: The liquid crystal display device includes, in order from the back side to the observation side, a first polarizing plate, a first retardation layer, a first substrate, a liquid crystal layer, a second substrate, a second retardation layer, and a second polarizing plate. The first substrate comprises: a reflective layer, a pair of electrodes capable of generating a lateral electric field in the liquid crystal layer, and a first horizontal alignment film in contact with the liquid crystal layer. The second substrate has a second horizontal alignment film in contact with the liquid crystal layer. The first phase difference layer includes a first λ / 2 plate and a first λ / 4 plate. The second phase difference layer includes a second λ / 2 plate and a second λ / 4 plate. At least one of the first phase difference layer and the second phase difference layer further includes a positive C plate. The liquid crystal layer includes a liquid crystal material having a negative dielectric anisotropy and is in a twisted orientation when no voltage is applied. Each pixel includes a reflective region for displaying by reflecting light through the reflective layer and a transmissive region for displaying by transmitting light.

2. The semi-transmissive liquid crystal display device according to claim 1, wherein: Satisfy any one of the following (i) to (iii): (i) the second phase difference layer includes a positive C plate, and the first phase difference layer does not include a positive C plate; (ii) the second phase difference layer comprises one positive C plate, and the first phase difference layer comprises two positive C plates; (iii) The first retardation layer and the second retardation layer each include two positive C plates.

3. The semi-transmissive liquid crystal display device according to claim 1 or 2, characterized in that: The first λ / 2 plate and the first λ / 4 plate are present in this order from the back side. The second λ / 2 plate and the second λ / 4 plate are present in this order from the observation surface side. The in-plane phase difference Re of the first λ / 2 plate and the second λ / 2 plate is substantially the same, The in-plane phase difference Re of the first λ / 4 plate and the second λ / 4 plate are substantially the same.

4. The semi-transmissive liquid crystal display device according to any one of claims 1 to 3, characterized in that: The positive C plate is located between the first λ / 2 plate and the first λ / 4 plate and / or between the second λ / 2 plate and the second λ / 4 plate.

5. The semi-transmissive liquid crystal display device according to any one of claims 1 to 4, characterized in that: The absolute value of the thickness direction phase difference Rth of the positive C plate is 150 to 270 nm.

6. The semi-transmissive liquid crystal display device according to any one of claims 1 to 5, characterized in that: The phase difference layer further comprises a second positive C plate, The second positive C plate is located between the first λ / 2 plate and the first polarizing plate and between the second λ / 2 plate and the second polarizing plate.

7. The semi-transmissive liquid crystal display device according to claim 6, wherein: The absolute value of the thickness direction phase difference Rth of the second positive C plate is 50 to 130 nm.

8. The semi-transmissive liquid crystal display device according to any one of claims 1 to 7, characterized in that: The twist angle of the liquid crystal layer when no voltage is applied is greater than or equal to 70° and less than or equal to 85°.

9. The semi-transmissive liquid crystal display device according to any one of claims 1 to 8, characterized in that: The product of the thickness d of the liquid crystal layer and the birefringence Δn of the liquid crystal material constituting the liquid crystal layer, that is, dΔn, is greater than or equal to 218 nm and less than or equal to 255 nm.

10. The semi-transmissive liquid crystal display device according to any one of claims 1 to 9, characterized in that: When the orientation direction of the liquid crystal molecules defined by the first horizontal orientation film is taken as a reference of 0° and the twist direction is set to a positive angle, The polarization axis of the first polarizing plate, the in-plane slow axis of the first λ / 2 plate, and the in-plane slow axis of the first λ / 4 plate are located at angles of 33.6° to 40.2°, 48.8° to 52.1°, and -74.8° to -68.2°, respectively.

11. The semi-transmissive liquid crystal display device according to any one of claims 1 to 10, characterized in that: When the orientation direction of the liquid crystal molecules defined by the first horizontal orientation film is taken as a reference of 0° and the twist direction is set to a positive angle, The polarization axis of the second polarizing plate, the in-plane slow axis of the second λ / 2 plate and the in-plane slow axis of the second λ / 4 plate are located at angles of -69.5° to -64.0°, -51.5° to -47.5° and -26.9° to -22.9° respectively.

12. The semi-transmissive liquid crystal display device according to any one of claims 1 to 11, characterized in that: At least one of the pair of electrodes includes a plurality of strip-shaped portions and a slit located between two adjacent strip-shaped portions among the plurality of strip-shaped portions.

13. The semi-transmissive liquid crystal display device according to any one of claims 1 to 12, characterized in that: The alignment direction of the liquid crystal molecules defined by the first horizontal alignment film is greater than or equal to -30° and less than or equal to 30°, with the direction in which the plurality of strip-shaped portions extend being 0° as a reference.

14. The semi-transmissive liquid crystal display device according to any one of claims 1 to 13, characterized in that: The semi-transmissive liquid crystal display device is of single-domain alignment.

15. The semi-transmissive liquid crystal display device according to any one of claims 1 to 14, characterized in that: The semi-transmissive liquid crystal display device performs display in a normally black mode.

16. The semi-transmissive liquid crystal display device according to any one of claims 1 to 15, characterized in that: One of the pair of electrodes is a pixel electrode provided in each of the plurality of pixels, and the other is a common electrode including a plurality of segments capable of functioning as touch sensor electrodes, respectively. The first substrate has a plurality of touch wirings respectively connected to the corresponding touch sensor electrodes.

17. The semi-transmissive liquid crystal display device according to any one of claims 1 to 16, characterized in that: The semi-transmissive liquid crystal display device further includes a light source.

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