Liquid crystal display device

Abstract

Provided is a liquid crystal display device capable of switching between a privacy mode and a public mode, and achieving high contrast even when displayed in the privacy mode. The liquid crystal display device of the present invention has an active matrix substrate having a first electrode, a first insulating layer, and a second electrode including a first linear electrode portion, a color filter substrate having a black matrix, a color filter, a third electrode including a plurality of second linear electrode portions, and a fourth electrode as a floating electrode, the third electrode and the fourth electrode are disposed between the black matrix and a liquid crystal layer, the second linear electrode portions extend in a second direction and overlap with portions of the black matrix extending in the second direction, the fourth electrode is disposed between the plurality of second linear electrode portions when viewed from above and overlaps with the black matrix, and a control circuit performs control to switch between applying a driving voltage to the third electrode and applying a constant voltage.

Description

TECHNICAL FIELD

[0001] The present application relates to a liquid crystal display device. BACKGROUND

[0002] A liquid crystal display device is a display device that utilizes a liquid crystal composition for display, and a representative display mode thereof is to apply a voltage to a liquid crystal composition enclosed between a pair of substrates, and to control the amount of light transmission by changing the alignment state of liquid crystal molecules in the liquid crystal composition according to the applied voltage.

[0003] Such a liquid crystal display device has the advantages of thinness, lightness, and low power consumption, and is used in a wide range of fields.

[0004] Currently, with regard to liquid crystal display devices, there is ongoing research into improving the viewing angle characteristics so that the same image can be observed from a narrow viewing angle range as well as from a wide viewing angle range. On the other hand, from the viewpoint of privacy protection, although the image can be observed from a narrow viewing angle range, there is ongoing research into display methods in which it is difficult to observe the image from a wide viewing angle range. For example, in Patent Literature 1, a liquid crystal display device is disclosed in which a narrow viewing angle mode and a wide viewing angle mode can be switched by controlling the voltage applied to a third electrode provided on a color filter substrate.

[0005] In Patent Literature 2, a liquid crystal display device is disclosed in which the viewing angle is switched by applying a voltage to a first electrode in a liquid crystal display device that includes a first substrate having a first electrode and a first alignment film, a liquid crystal layer, and a second substrate having a second electrode, a third electrode, and a second alignment film.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent Application Publication No. 2021-67852

[0009] Patent Literature 2: U.S. Patent Application Publication No. 2017 / 0059898 Patent Literature 3: Japanese Patent Application Publication No. 2002-124112 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] According to the research by the present inventors, when a voltage is applied to an electrode provided on a color filter substrate having a black matrix, light leakage occurs in the case of display in a privacy mode (narrow viewing angle mode), and sometimes the front contrast ratio decreases. The present inventors researched the cause of the above-mentioned light leakage, and found that when a voltage is applied to an electrode provided on a color filter substrate, the black matrix becomes charged (charged), an undesirable electric field is formed in the liquid crystal layer, as a result, light leakage occurs, and in the privacy mode, the front contrast ratio decreases.

[0012] The liquid crystal display device disclosed in Patent Document 2 described above has a first electrode on the opposing substrate side that is a flat plate-shaped whole electrode, so a longitudinal electric field is generated throughout the liquid crystal panel in the plane thereof when a voltage is applied to the first electrode, and thus it is difficult to obtain a high front contrast ratio.

[0013] The present application was achieved in view of the above-described circumstances, and has an object to provide a liquid crystal display device capable of switching between a privacy mode and a public mode, and capable of achieving a high contrast ratio even in the case of display in the privacy mode.

[0014] Solution to the problem

[0015] (1) A liquid crystal display device of an embodiment of the present application is a liquid crystal display device having a liquid crystal panel in which a plurality of pixels are arranged in a matrix shape, and a control circuit, the liquid crystal panel having, in order, an active matrix substrate, a liquid crystal layer, and a color filter substrate, the active matrix substrate having, in order, a first substrate, a first electrode, a first insulating layer, and a second electrode, the second electrode including a first linear electrode portion arranged for each of the pixels and extending in a first direction, the color filter substrate having a second substrate, a black matrix arranged between the plurality of pixels, a color filter, a third electrode including a plurality of second linear electrode portions, and a fourth electrode that is a floating electrode, the third electrode and the fourth electrode being arranged between the black matrix and the liquid crystal layer, the second linear electrode portions extending in a second direction that intersects the first direction, and overlapping with portions of the black matrix that extend in the second direction, the fourth electrode being arranged between the plurality of second linear electrode portions when viewed from above, and overlapping with at least a portion of the black matrix, and the control circuit controls switching between application of a drive voltage to the third electrode and application of a constant voltage.

[0016] (2) In addition, a liquid crystal display device of an embodiment of the present application is based on the structure of (1) above, and the fourth electrode is arranged on the same layer as the third electrode.

[0017] (3) In addition, a liquid crystal display device of an embodiment of the present application is based on the structure of (1) or (2) above, and the third electrode further includes a third linear electrode portion arranged between the plurality of second linear electrode portions, the third linear electrode portion being arranged so as to extend in the second direction when viewed from above, and overlapping with an optical opening portion of a pixel.

[0018] (4) In addition, a liquid crystal display device of an embodiment of the present application is based on the structure of (3) above, and the fourth electrode includes a fourth linear electrode portion extending in the second direction and arranged so as to overlap with the optical opening portion of the pixel,

[0019] The fourth linear electrode is arranged between the plurality of second linear electrode portions and the third linear electrode portion.

[0020] (5) In addition, a liquid crystal display device of one embodiment of the present application is the structure described in (3) above, and the fourth electrode includes a plurality of island-shaped electrodes that are independent of each other in plan view, the plurality of island-shaped electrodes being arranged between the plurality of second linear electrode portions and the third linear electrode portion.

[0021] (6) In addition, a liquid crystal display device of one embodiment of the present application is the structure described in any one of (1) to (5) above, and a dielectric layer is provided between the third electrode and the liquid crystal layer.

[0022] (7) In addition, a liquid crystal display device of one embodiment of the present application is the structure described in any one of (1) to (6) above, and the third electrode is formed of a transparent conductive material.

[0023] (8) In addition, a liquid crystal display device of one embodiment of the present application is the structure described in any one of (1) to (7) above, and the active matrix substrate includes a gate wire and a source wire arranged so as to cross the gate wire, the gate wire extending in the second direction.

[0024] (9) In addition, a liquid crystal display device of one embodiment of the present application is the structure described in (8) above, and the plurality of second linear electrode portions each overlap at least a part of the gate wire in plan view.

[0025] (10) In addition, a liquid crystal display device of one embodiment of the present application is the structure described in any one of (1) to (9) above, and the control circuit is capable of switching between a first display mode and a second display mode, the first display mode displaying a first image that can be observed from a narrow viewing angle range including a normal direction of the liquid crystal panel, the second display mode enabling the first image to be observed from a wide viewing angle range including the narrow viewing angle range, the control circuit performing control to apply the driving voltage to the third electrode in the first display mode and performing control to apply the constant voltage to the third electrode in the second display mode.

[0026] (11) In addition, a liquid crystal display device of one embodiment of the present application is the structure described in (10) above, and a backlight including a light source and a light-shielding shutter arranged on the liquid crystal panel side of the light source is provided on the back surface of the liquid crystal panel, and the control circuit performs control so that the luminance of the backlight in the first display mode is lower than the luminance of the backlight in the second display mode.

[0027] Effects of Invention

[0028] According to the present invention, a liquid crystal display device is provided that can switch between a privacy mode and a public mode, and can achieve high contrast even when displayed in privacy mode. Attached Figure Description

[0029] Figure 1 This is a plan view illustrating an example of a liquid crystal display device according to the first embodiment.

[0030] Figure 2 yes Figure 1 A planar schematic diagram of a pixel in the liquid crystal display device shown.

[0031] Figure 3 It is along Figure 1 A cross-sectional schematic diagram of line Y1-Y1' in the diagram.

[0032] Figure 4 It is along Figure 1 A cross-sectional schematic diagram of line X1-X1' in the diagram.

[0033] Figure 5 It is shown in Figure 4 A cross-sectional schematic diagram of an example of a liquid crystal panel having a dielectric layer (second dielectric layer) disposed thereon.

[0034] Figure 6 This is a plan view illustrating an example of a liquid crystal display device according to the second embodiment.

[0035] Figure 7 yes Figure 6 A planar schematic diagram of a pixel in the liquid crystal display device shown.

[0036] Figure 8A yes Figure 6 A magnified planar view of the boundary portion of adjacent pixels is shown.

[0037] Figure 8B It is shown Figure 6 A magnified planar view of another example of the boundary portion of adjacent pixels.

[0038] Figure 8C It is shown Figure 6 An enlarged planar view of yet another example of the boundary portion of adjacent pixels is shown.

[0039] Figure 9 It is along Figure 6 A cross-sectional diagram of the Y2-Y2' line.

[0040] Figure 10 It is along Figure 6 A cross-sectional view of line X2-X2' in the diagram.

[0041] Figure 11 It is alongFigure 6 A cross-sectional view of line X3-X3' in the diagram.

[0042] Figure 12 It is shown in Figure 11 A cross-sectional schematic diagram of an example of a liquid crystal panel having a dielectric layer (second dielectric layer) disposed thereon.

[0043] Figure 13 This is a block diagram schematically illustrating the display methods of the first display mode and the second display mode in the third embodiment.

[0044] Figure 14 This is a plan view illustrating an example of a display unit in a liquid crystal panel.

[0045] Figure 15 This is a plan view illustrating an example of a color element in a color display scenario using a soft viewing angle control function.

[0046] Figure 16 This is a block diagram schematically illustrating the display method in the case of displaying a viewing angle control pattern in the third embodiment.

[0047] Figure 17 This is an exploded perspective view schematically showing a backlight source equipped with the light-blocking louvers used in the fourth embodiment.

[0048] Figure 18 This is a block diagram schematically illustrating the display methods of the first display mode and the second display mode in the fourth embodiment.

[0049] Figure 19 This is a block diagram schematically illustrating the display method in the case of displaying a viewing angle control pattern in the fourth embodiment.

[0050] Figure 20 This is a cross-sectional schematic diagram of the liquid crystal panel of Comparative Example 1.

[0051] Figure 21 This is a table summarizing the simulation results of the contrast of Examples 1-3 and Comparative Example 1.

[0052] Figure 22 This is a cross-sectional schematic diagram showing the electric field of the liquid crystal panel of Embodiment 1.

[0053] Figure 23 This is a cross-sectional schematic diagram illustrating the case in Example 4 where the backlight is linked and the display is performed in a common mode.

[0054] Figure 24 This is a cross-sectional schematic diagram illustrating the case in Example 4 where the backlight is activated and the display is in privacy mode.

[0055] Figure 25 is a graph showing the contrast of the front surface and polar angle 45° of Example 4.

[0056] Figure 26 is a graph showing the luminance at white display of the front surface and polar angle 45° of Example 4.

[0057] Figure 27 is a graph showing the luminance at black display of the front surface and polar angle 45° of Example 4. DETAILED DESCRIPTION

[0058] Hereinafter, embodiments of the present application will be described. The present application is not limited to the contents described in each of the following embodiments, and design changes can be appropriately made within a range satisfying the constitution of the present application. Further, in the following description, the same symbols are commonly used between different drawings in the same portion or a portion having the same function, and repeated description thereof is appropriately omitted. Each aspect of the present application can be appropriately combined within a range not departing from the gist of the present application.

[0059] (First Embodiment)

[0060] The liquid crystal display device related to the first embodiment is a liquid crystal display device having a liquid crystal panel in which a plurality of pixels are arranged in a matrix shape and a control circuit, the liquid crystal panel having, in order, an active matrix substrate, a liquid crystal layer, and a color filter substrate, the active matrix substrate having, in order, a first substrate, a first electrode, a first insulating layer, and a second electrode, the second electrode including a first linear electrode portion arranged for each of the plurality of pixels and extending in a first direction, the color filter substrate having a second substrate, a black matrix arranged between the plurality of pixels, a color filter, a third electrode including a plurality of second linear electrode portions, and a fourth electrode as a floating electrode, the third electrode and the fourth electrode being arranged between the black matrix and the liquid crystal layer, the second linear electrode portions extending in a second direction intersecting the first direction and overlapping with a portion of the black matrix extending in the second direction, the fourth electrode being arranged between the plurality of second linear electrode portions when viewed from above and overlapping with at least a portion of the black matrix, and the control circuit controlling switching between application of a drive voltage to the third electrode and application of a constant voltage.

[0061] Hereinafter, the liquid crystal display device related to the first embodiment will be described using the drawings. Figure 1 is a plan view schematically showing an example of the liquid crystal display device related to the first embodiment. Figure 2 is a plan view schematically showing an example of the liquid crystal display device related to the first embodiment. Figure 1 is a plan view schematically showing a pixel of the liquid crystal display device shown in Figure 3 is a cross-sectional view along the Y1-Y1' line in Figure 1 is a cross-sectional view along the Y1-Y1' line in Figure 4 is a cross-sectional view along the Y1-Y1' line inFigure 1 A cross-sectional schematic diagram of line X1-X1' in the diagram.

[0062] (LCD panel)

[0063] like Figure 1 As shown, the liquid crystal display device according to the first embodiment has a liquid crystal panel 100A with a plurality of pixels arranged in a matrix. The active matrix substrate may also have gate wiring 1 and source wiring 2 arranged intersecting with the gate wiring 1. In this specification, "pixel" refers to... Figure 1 as well as Figure 2 As shown, this is the region surrounded by two adjacent gate wirings 1 and two adjacent source wirings 2. In this specification, unless otherwise specified, the first pixel 70 and the second pixel 71, described later, are simply referred to as pixels. A thin-film transistor 3 (TFT) may also be configured as a switching element at the intersection of the gate wirings 1 and the source wirings 2.

[0064] Preferably, optical openings configured to allow light to pass through the liquid crystal panel 100A are provided in each of the multiple pixels. These optical openings are... Figure 1 The area inside the pixel shown is enclosed by a dashed line. When the liquid crystal panel 100A is a transmissive or semi-transmissive type, the aforementioned optical opening allows light emitted from the back of the liquid crystal panel 100A to pass through towards the front surface of the liquid crystal panel 100A. When the liquid crystal panel 100A is a reflective or semi-transmissive type, the aforementioned optical opening allows incident light incident from the outside of the liquid crystal panel 100A and reflected light reflected from the inside of the liquid crystal panel 100A and emitted towards the outside of the liquid crystal panel 100A to pass through. Furthermore, the aforementioned optical opening may overlap with transmissive components such as polarizers or color filters when viewed from above. In the first embodiment, the case where the liquid crystal panel 100A is a transmissive type will be described.

[0065] like Figure 3 and Figure 4 As shown, the liquid crystal panel 100A sequentially includes an active matrix substrate 10, a liquid crystal layer 20, and a color filter substrate 30. In this specification, the side closer to the screen (display surface) of the liquid crystal display device is referred to as the "observer side (front side)," and the side farther from the screen (display surface) of the liquid crystal display device is referred to as the "back side." The view viewed from the normal direction of the front side is also called a top view.

[0066] The active matrix substrate 10 sequentially comprises a first substrate 11, a first electrode 12, a first insulating layer 13, and a second electrode 14. The first electrode 12 and the second electrode 14 are stacked with the first insulating layer 13 in between, forming an FFS (Fringe Field Switching) type electrode structure. For example, inorganic materials such as silicon oxide and silicon nitride can be used as the material for the first insulating layer 13.

[0067] In the first embodiment, the first electrode 12 is preferably a monolithic electrode. A monolithic electrode refers to a flat electrode that, when viewed from above, does not have slits or openings in the area overlapping with the optical opening of a pixel. The first electrode 12 can be configured for each of multiple pixels, can be configured for multiple pixels in a shared manner, or can be formed throughout the entire display area regardless of pixel boundaries. Examples of materials for the first electrode 12 include transparent conductive materials such as indium tin oxide (ITO) and indium zinc oxide (IZO).

[0068] The second electrode 14 is disposed in each pixel. For example... Figure 1 and Figure 2 As shown, the second electrode 14 includes a first linear electrode portion 14a extending along a first direction D1. The first linear electrode portion 14a may extend at least partially along the first direction D1, or it may include linear electrode portions extending in a direction different from the first direction D1. There may be multiple first linear electrode portions 14a. The ends of adjacent first linear electrode portions 14a may be connected by an electrode material, and an opening surrounded by the electrode material may be provided. Alternatively, the second electrode 14 may be a comb-tooth electrode that opens the ends of adjacent first linear electrode portions 14a, or a slit may be provided between adjacent first linear electrode portions 14a. Figure 1 and Figure 2 In the example shown, the ends of a plurality of first linear electrode portions 14a are connected by electrode material and are provided with openings 14b.

[0069] The width of the first linear electrode portion 14a can be, for example, 2 to 5 μm. The width of the slit or opening can be, for example, 2 to 5 μm. The width of the first linear electrode portion 14a, the width of the slit or opening are the widths in the direction orthogonal to the first direction D1.

[0070] The material used for the second electrode 14 can be, for example, a transparent conductive material such as ITO or IZO. The second electrode 14 is electrically connected to the corresponding source wiring 2 via, for example, the semiconductor layer of the TFT 3.

[0071] Preferably, either the first electrode 12 or the second electrode 14 is electrically coupled across the plurality of pixels. "Across the plurality of pixels" means configured to overlap with the plurality of pixels across their boundaries. By electrically coupling across the plurality of pixels, a common constant voltage can be applied to either the first electrode 12 or the second electrode 14 relative to the plurality of pixels.

[0072] There are no particular limitations on the first substrate 11 and the second substrate 31 described later; for example, a resin substrate such as polycarbonate or a glass substrate can be used.

[0073] The liquid crystal layer 20 contains liquid crystal molecules. The liquid crystal molecules are preferably positive liquid crystal molecules (positive type) with a positive dielectric constant anisotropy (Δε) as defined by the following formula (L). Furthermore, the liquid crystal molecules are preferably parallel-oriented in a state where no voltage is applied (voltage-unapplied state). The direction of the long axis of the liquid crystal molecules in the voltage-unapplied state is also referred to as the initial orientation direction of the liquid crystal molecules. The aforementioned voltage-unapplied state includes the case where a voltage less than the threshold voltage of the liquid crystal molecules is applied to the liquid crystal layer.

[0074] Δε = (dielectric constant along the long axis of the liquid crystal molecule) - (dielectric constant along the short axis of the liquid crystal molecule) (L)

[0075] The color filter substrate 30 includes a second substrate 31, a black matrix 33, a color filter 32, a third electrode 34, and a fourth electrode 35. In the first embodiment, as... Figure 4 As shown, the color filter substrate 30 sequentially comprises a second substrate 31, a black matrix 33, a color filter 32, and a first dielectric layer 50, and a third electrode 34 and a fourth electrode 35 are disposed on the first dielectric layer 50.

[0076] By applying a driving voltage to the third electrode 34, an electric field can be generated in the thickness direction of the liquid crystal layer 20, enabling the switching between privacy mode and public mode. The display method will be described later. The third electrode 34 can also be formed of a transparent conductive material. Examples of such transparent conductive materials include ITO and IZO.

[0077] like Figure 1 and Figure 2 As shown, the third electrode 34 includes a plurality of second linear electrode portions 34a. These second linear electrode portions 34a extend along a second direction D2 that intersects the first direction D1 when viewed from above, and overlap with the portion of the black matrix 33 extending along the second direction D2. The first direction D1 is the extending direction of the first linear electrode portions 14a of the second electrode 14. The second linear electrode portions 34a can also be described as horizontal stripe electrodes relative to the first direction D1. Alternatively, they can extend along the end of the second direction D2 of a pixel (in... Figure 1 ,Figure 2 The second linear electrode portion 34a is preferably not overlapped with the optical opening portion in plan view. Since the third electrode 34 has a portion not overlapped with the optical opening portion, the longitudinal electric field at the opening portion of the pixel is difficult to act when displaying in the public mode, and thus high transmittance and high contrast can be obtained.

[0078] The second linear electrode portion 34a is preferably not overlapped with the optical opening portion in plan view. Since the third electrode 34 has a portion not overlapped with the optical opening portion, the longitudinal electric field at the opening portion of the pixel is difficult to act when displaying in the public mode, and thus high transmittance and high contrast can be obtained.

[0079] The angle θ1 between the first direction D1 and the second direction D2 is preferably 80° or more and 100° or less, and more preferably 85° or more and 95° or less. The second direction D2 can be parallel to the absorption axis 62A of the second polarizing plate 62 or the absorption axis 61A of the first polarizing plate 61, and in the first embodiment, as shown in FIG. 1, the second direction D2 is parallel to the absorption axis 62A of the second polarizing plate 62 (0°-180° azimuth). Figure 1

[0080] The plurality of second linear electrode portions 34a are preferably electrically connected to each other. The second linear electrode portion 34a can also be connected by a connection portion at the end portion of the liquid crystal panel, for example.

[0081] The second linear electrode portion 34a is overlapped with the black matrix 33, and thus if it is a conventional liquid crystal display device, when a voltage is applied to the electrode provided to the color filter substrate having the black matrix, the black matrix is charged, and as a result, in the privacy mode, the front contrast is sometimes reduced. On the other hand, in the present embodiment, as described later, by providing the fourth electrode 35 as a floating electrode to the color filter substrate 30, reduction of the front contrast in the privacy mode can be suppressed.

[0082] The gate wiring 1 can also extend in the second direction D2, that is, the extension direction of the second linear electrode portion 34a. The plurality of second linear electrode portions 34a can each be overlapped with at least a portion of the gate wiring 1 in plan view. From the viewpoint of improving the privacy performance, the width of the second linear electrode portion 34a can be wider than the width of the gate wiring 1.

[0083] ​The width of the second linear electrode portion 34a is preferably 5 μm or more. The upper limit of the width of the second linear electrode portion 34a is not particularly limited, and can be, for example, 50 μm, as long as it does not overlap with the optical aperture. The more preferable lower limit of the width of the second linear electrode portion 34a is 15 μm, and the more preferable upper limit is 40 μm. The width of the second linear electrode portion 34a is the electrode width in the direction orthogonal to the second direction D2.

[0084] The third electrode 34 can further include a third linear electrode portion 34b disposed between the plurality of second linear electrode portions 34a. The third linear electrode portion 34b is preferably disposed so as to extend in the above-described second direction D2 in plan view, and overlap with the optical aperture of the pixel. The third electrode 34 includes the third linear electrode portion 34b, and thus can further suppress the contrast in the case of viewing from the left-right direction while maintaining the high level of the front contrast. One third linear electrode portion 34b can be disposed at a position overlapping with the optical aperture of the pixel, or a plurality of third linear electrode portions 34b can be disposed.

[0085] In the case where the third linear electrode portion 34b is a plurality, the plurality of third linear electrode portions 34b are preferably electrically connected to each other. The plurality of third linear electrode portions 34b can be connected, for example, at the end portion of the liquid crystal panel by a connection portion. In addition, the third linear electrode portion 34b is preferably electrically connected to the second linear electrode portion 34a, and preferably the same voltage is applied as a whole of the third electrode 34.

[0086] The width of the third linear electrode portion 34b is preferably narrower than the width of the second linear electrode portion 34a. The width of the third linear electrode portion 34b is preferably 2.5 μm or more and 12 μm or less. By setting the width of the third linear electrode portion 34b to the above-described range, the front contrast in the privacy mode can be improved, and the contrast in the left-right direction can be sufficiently suppressed. The more preferable lower limit of the width of the third linear electrode portion 34b is 3 μm, and the more preferable upper limit is 7 μm. From the viewpoint of being able to improve the front contrast in the public mode, it is more preferable that the width of the third linear electrode portion 34b be 7 μm or less. The width of the third linear electrode portion 34b is the electrode width in the direction orthogonal to the second direction D2.

[0087] In the case where a plurality of third linear electrode portions 34b are disposed, the third linear electrode portions 34b are preferably disposed at equal intervals. The distance between adjacent third linear electrode portions 34b is preferably 2.5 μm or more and 7 μm or less. The more preferable lower limit of the distance between adjacent third linear electrode portions 34b is 3 μm, and the more preferable upper limit is 5 μm.

[0088] The color filter substrate 30 has a fourth electrode 35 as a floating electrode. A floating electrode is an electrode that is not electrically connected to other electrodes or a power source, and the potential of the floating electrode is determined by the sum of the electrostatic capacitances of the electrodes present in the vicinity. The fourth electrode 35 is not electrically connected to the first electrode 12, the second electrode 14, and the third electrode 34. As the material of the fourth electrode 35, transparent conductive materials such as ITO, IZO, and the like can be given.

[0089] In the case where the fourth electrode 35 is not provided, if a voltage is applied to the third electrode 34 provided to the color filter substrate, an electric field that is not parallel or orthogonal to the absorption axis of the polarizing plate in plan view is generated between the charged (electrified) black matrix 33 and the electrode on the active matrix substrate side, and sometimes the long axis (director) of the liquid crystal molecules deviates from the absorption axis of the polarizing plate, the alignment of the liquid crystal molecules is disturbed, and light leakage (black floating) occurs when viewed from the front in black display. As a result, the front contrast ratio in privacy mode sometimes decreases. However, in the present embodiment, by providing the third electrode 34 and the fourth electrode 35 between the black matrix 33 and the liquid crystal layer 20, and configuring the fourth electrode 35 so as to be disposed between the plurality of second linear electrode portions 34a in plan view and to overlap at least a part of the black matrix 33, even if the black matrix 33 is electrified, the electric field action on the liquid crystal layer 20 can be mitigated by shielding or reducing the electric field strength of the electric field from the third electrode 34 toward the black matrix 33 (see Figure 22 ). As a result, the generation of an electric field that deviates from the absorption axis of the polarizing plate between the black matrix 33 and the electrode on the active matrix substrate 10 side can be suppressed, and the front contrast ratio can be maintained high.

[0090] The fourth electrode 35 is preferably provided in the same layer as the third electrode 34 or between the third electrode 34 and the black matrix 33. In Figure 4 , an example in which the fourth electrode 35 and the third electrode 34 are provided in the same layer is shown, and the third electrode 34 and the fourth electrode 35 are both formed on the first dielectric layer 50. By being provided in the same layer, the third electrode 34 and the fourth electrode 35 do not have other layers such as an insulating layer between them in a cross-sectional view of the liquid crystal panel. By providing the third electrode 34 and the fourth electrode 35 in the same layer, the number of production steps is reduced, and the manufacturing cost can be reduced.

[0091] In the first embodiment, as Figure 1 and Figure 2As shown, the fourth electrode 35 includes a fourth linear electrode portion 35a extending in the second direction D2 and configured to overlap with the optical opening portion of the pixel described above. The fourth linear electrode portion 35a is configured between the plurality of second linear electrode portions 34a and the third linear electrode portions 34b in plan view. In the case where the third linear electrode portions 34b are a plurality, the fourth linear electrode portion 35a is preferably configured at least one of between the second linear electrode portion 34a and the third linear electrode portion 34b, or between adjacent third linear electrode portions 34b. The plurality of fourth linear electrode portions 35a can also be configured independently of each other in plan view without being electrically connected.

[0092] The fourth linear electrode portion 35a included in the fourth electrode 35 is preferably configured between the second linear electrode portion 34a and the third linear electrode portion 34b of the third electrode 34, or between adjacent third linear electrode portions 34b in plan view.

[0093] The fourth linear electrode portion 35a can also be configured between the second linear electrode portion 34a and the third linear electrode portion 34b, and between adjacent third linear electrode portions 34b in plan view. Further, the fourth linear electrode portion 35a and the second linear electrode portion 34a and / or the third linear electrode portion 34b are more preferably alternately configured in plan view. By being thus configured, the electric field generated in the liquid crystal layer 20 is substantially parallel or substantially orthogonal to the absorption axis of the polarizing plate in plan view, and thus light leakage from the front when viewed in the privacy mode black display is suppressed. Therefore, in the privacy mode, the front contrast can be improved, and the contrast from the oblique direction is reduced, and the privacy performance can be improved. The direction of the alternate configuration can be, for example, a direction along the first direction D1.

[0094] The width W35a of the fourth linear electrode portion 35a is preferably 2.5 pm or more and 5 pm or less. The more preferable lower limit of the width W35a of the fourth linear electrode portion 35a is 3 pm, and the more preferable upper limit is 4 pm. The width W35a of the fourth linear electrode portion 35a is the electrode width in the direction orthogonal to the second direction D2.

[0095] If the distance between the second linear electrode portion 34a and the fourth linear electrode portion 35a adjacent in plan view is set as dl, and the distance between the third linear electrode portion 34b and the fourth linear electrode portion 35a adjacent is set as d2, the distances dl and d2 are each preferably 2 pm or more and 7 pm or less. By setting the distances dl and d2 to the above range, the contrast in the left-right direction in the privacy mode can be favorably suppressed. The more preferable lower limit of the distances dl and d2 is 3 pm, and the more preferable upper limit is 4 pm. From the viewpoint of being able to improve the front contrast in the privacy mode, the above distances dl and d2 are more preferably 7.5 pm or less. Both the distances dl and d2 are the distances in the direction orthogonal to the second direction D2.

[0096] The color filter 32 is disposed in each pixel so as to overlap the optical opening portion described above when the liquid crystal panel 100A is viewed from the front side. The color filter 32 includes, for example, a red color filter 32R, a green color filter 32G, and a blue color filter 32B. The color filter 32 can also be formed continuously with the same color in the row direction or the column direction of the liquid crystal panel 100A. The color filter 32 is preferably a dielectric layer.

[0097] The black matrix 33 is disposed between the plurality of pixels. The black matrix 33 can be disposed between the optical opening portions described above that are adjacent in the row direction or the column direction, or can be disposed around the optical opening portion when viewed from above. As the black matrix 33, a black matrix commonly used in the field of liquid crystal display devices can be used, but is preferably composed of a resin, and more preferably composed of a black resin containing a black pigment or dye. The black matrix 33 has, for example, a specific resistance of 1.0 x 10 10 ~ 1.0 x 10 13 (Ω-cm).

[0098] The first dielectric layer 50 is preferably disposed between the black matrix 33 and the third electrode 34. By disposing the first dielectric layer 50, the distance between the black matrix 33 and the third electrode 34 becomes farther, and thus the charging of the black matrix 33 caused by the application of voltage to the third electrode 34 can be reduced. The dielectric constant ε of the first dielectric layer 50 can be, for example, ε = 3 to 4.

[0099] The first dielectric layer 50 is a layer different from the color filter 32, and is, for example, a layer formed of a resin having light transmittance. The total light transmittance of the first dielectric layer 50 is preferably 80% or more. In the present specification, the total light transmittance refers to the total light transmittance measured according to JIS K 7361-1. As the first dielectric layer 50, a resin such as an acrylic resin, a polyimide resin, or the like can be used.

[0100] The thickness of the first dielectric layer 50 is preferably 0.5 μm or more and 4 μm or less. If the first dielectric layer 50 is too thick, parallax mismatching from the inclination occurs, and sometimes the desired color cannot be obtained. In addition, if the thickness of the first dielectric layer 50 is 4 μm or more, unevenness is easily generated on the surface of the first dielectric layer 50, and sometimes display unevenness occurs.

[0101] Although not shown, an alignment film can be disposed between the active matrix substrate 10 and the liquid crystal layer 20, and between the color filter substrate 30 and the liquid crystal layer 20, respectively. The alignment film controls the initial orientation direction of the liquid crystal molecules in a state in which voltage is not applied. The alignment film is preferably a horizontal alignment film. The horizontal alignment film preferably sets the pre-tilt angle of the liquid crystal molecules with respect to the surface of the alignment film in the initial state (in a state in which voltage is not applied to the liquid crystal layer) to 0° to 1°.

[0102] In addition, the first polarizing plate 61 and the second polarizing plate 62 can be disposed on the side of the active matrix substrate 10 opposite to the liquid crystal layer 20 and on the side of the color filter substrate 30 opposite to the liquid crystal layer 20, respectively. The absorption axis 61A of the first polarizing plate 61 and the absorption axis 62A of the second polarizing plate 62 are preferably orthogonal Nicol disposed in a manner that they are orthogonal to each other. In Figure 1 In the present embodiment, the absorption axis 62A of the second polarizing plate 62 is set to 0°-180° azimuth, and the absorption axis 61A of the first polarizing plate 61 is set to 90°-270° azimuth. The first polarizing plate 61 and the second polarizing plate 62 are preferably linear polarizing plates.

[0103] Figure 5 is a cross-sectional schematic view showing an example in which a dielectric layer (second dielectric layer) is disposed on the liquid crystal panel shown in Figure 4 As shown in Figure 5 The liquid crystal panel 100B can also have a dielectric layer (second dielectric layer 51) between the third electrode 34 and the liquid crystal layer 20. The second dielectric layer 51 is a layer different from the alignment film, and is preferably disposed between the third electrode 34 and the alignment film. In Figure 5 In the present embodiment, the absorption axis 62A of the second polarizing plate 62 is set to 0°-180° azimuth, and the absorption axis 61A of the first polarizing plate 61 is set to 90°-270° azimuth. The first polarizing plate 61 and the second polarizing plate 62 are preferably linear polarizing plates.

[0104] By disposing the second dielectric layer 51, in the common mode, generation of an unnecessary vertical electric field generated between the third electrode 34 and the electrode on the active matrix substrate side can be suppressed. As a result, since the liquid crystal molecules are hardly made to stand, horizontal electric field driving can be performed, and thus the transmittance at the time of white display on the front surface and the front contrast ratio at the time of display in the common mode can be improved. The second dielectric layer 51 can be formed of the same material as the first dielectric layer 50. The total light transmittance of the second dielectric layer 51 is preferably 80% or more.

[0105] The dielectric constant ε of the second dielectric layer 51 can be, for example, ε = 3-4. The thickness of the second dielectric layer 51 is preferably 0.5 μm or more and 4 μm or less. When the thickness exceeds 4 μm, parallax color mixing can sometimes occur, and the display quality can be reduced.

[0106] The liquid crystal display device according to the first embodiment can also be provided with a backlight 300 on the back side of the liquid crystal panel (the active matrix substrate 10 side). There is no particular limitation on the backlight 300, and a backlight generally used in the field of liquid crystal display devices can be used. The backlight 300 can be either a transmissive type or a side light type. From the viewpoint of further improving privacy in the privacy mode, as the backlight 300, a backlight provided with a light-shielding shutter described later can also be used.

[0107] The liquid crystal panel according to the first embodiment can also be an in-cell touch panel. In the case where the liquid crystal panel 100A or 100B is an in-cell touch panel, the active matrix substrate 10 can also have a touch panel wiring. The above-described touch panel wiring can be configured to overlap the source wiring 2 in the same width as the source wiring 2 when viewed from the top, for example. In addition, the above-described touch panel wiring can be configured to be between the first electrode 12 and the second electrode 14 when viewed from the section. Since the fourth electrode 35 is in a floating state, the signal-to-noise ratio (S / N ratio) can be improved regardless of the resistance of the fourth electrode 35, and thus, charging of the black matrix 33 can be prevented, and the electrostatic capacitance between the finger and the touch panel wiring can be ensured.

[0108] (Second Embodiment)

[0109] The liquid crystal display device according to the second embodiment has the same configuration as the first embodiment except that the shape of the fourth electrode is different. Figure 6 is a plan view schematically showing an example of the liquid crystal display device according to the second embodiment. Figure 7 is a plan view schematically showing an example of the liquid crystal display device according to the second embodiment. Figure 6 is a plan view schematically showing an example of the liquid crystal display device according to the second embodiment.

[0110] As shown in Figure 6 and Figure 7 in the liquid crystal panel 100C exemplified in the second embodiment, the fourth electrode 35 includes a plurality of island-shaped electrodes 35b that are independent from each other when viewed from the top. Each of the plurality of island-shaped electrodes 35b is configured between the plurality of second linear electrode portions 34a and the third linear electrode portion 34b when viewed from the top. In the case where the third linear electrode portion 34b is a plurality, it is preferable that at least one of the plurality of island-shaped electrodes 35b is configured at least one of between the second linear electrode portion 34a and the third linear electrode portion 34b or between adjacent third linear electrode portions 34b.

[0111] The island-shaped electrode 35b is a floating electrode, and by providing the island-shaped electrode 35b, it is possible to suppress generation of an electric field deviating from the absorption axis of the polarizing plate between the black matrix 33 and the electrode on the active matrix substrate 10 side, and it is possible to prevent the occurrence of the above-described light leakage. Also, the island-shaped electrode 35b is provided at a position overlapping the black matrix 33, and thus the area in which the island-shaped electrode 35b and the optical opening portion of the above-described pixel do not overlap when viewed in plan view is larger than in the first embodiment, and thus it is possible to further improve the transmittance at the time of white display compared to the first embodiment.

[0112] The plurality of island-shaped electrodes 35b are preferably not in contact with each other when viewed in plan view, and are not electrically connected to each other. The planar shape of the island-shaped electrode 35b is not particularly limited, and can be, for example, a square, a rectangular, a polygon such as a parallelogram, an ellipse, a circle, or the like.

[0113] The width of the island-shaped electrode 35b is preferably 2.5 μm or more and 7 μm or less. The more preferable lower limit of the width of the above-described island-shaped electrode 35b is 3.5 μm, and the more preferable upper limit from the viewpoint of manufacturing is 5 μm. The width of the above-described island-shaped electrode 35b refers to the maximum width of the electrode in a direction orthogonal to the second direction D2.

[0114] Figure 8A is Figure 6 An enlarged plan view of a boundary portion of adjacent pixels. Figure 8B is an enlarged plan view of a boundary portion of adjacent pixels. Figure 6 An enlarged plan view of another example of a boundary portion of adjacent pixels.

[0115] Figure 8C is an enlarged plan view of another example of a boundary portion of adjacent pixels. Figure 6 An enlarged plan view of still another example of a boundary portion of adjacent pixels. Figures 8A-8C In the formula, f0 is a reference line in a case in which the outer edge of the island-shaped electrode 35b coincides with the outer edge of the black matrix 33.

[0116] One island-shaped electrode 35b can also be provided so as to straddle two pixels adjacent in the second direction D2. The island-shaped electrode 35b can overlap the black matrix 33 at least in part, and on a straight line passing through the optical opening portion of the pixel in the second direction D2, as Figure 8A indicated, the width of the island-shaped electrode 35b can be wider than the width of the black matrix 33, as Figure 8B indicated, the width of the island-shaped electrode 35b can be the same as the width of the black matrix 33, as Figure 8C indicated, the width of the island-shaped electrode 35b can be the same as the width of the black matrix 33, and as Figure 8C indicated, the width of the island-shaped electrode 35b can be narrower than the width of the black matrix 33.

[0117] Figure 8AThis example illustrates the case where, in the second direction D2, the outer edge of the island electrode 35b is located closer to the optical opening of the pixel than the outer edge of the black matrix 33. In the second direction D2, a portion of the island electrode 35b is exposed at the optical opening of the pixel. When the width of the island electrode 35b is wider than the width of the black matrix 33, let f be the distance in the second direction D2 from the outer edge of the island electrode 35b to the outer edge of the black matrix 33. + Then the above distance f + Preferably, the distance is greater than 0 μm and less than 5 μm. The aforementioned distance f + The preferred lower limit is 0.5 μm, and the preferred upper limit is 3 μm.

[0118] like Figure 8C As shown, when the width of the island electrode 35b is narrower than the width of the black matrix 33, let f be the distance from the outer edge of the island electrode 35b to the outer edge of the black matrix 33 in the second direction D2. - Then the above distance f - Preferably, the distance is greater than 0 μm and less than 4 μm. The aforementioned distance f - The preferred lower limit is 0.5 μm, and the preferred upper limit is 3 μm.

[0119] When the fourth electrode 35 includes an island electrode 35b, transparent conductive materials such as ITO and IZO can be used, and aluminum, molybdenum nitride, etc. can also be used when the width of the island electrode 35b is less than or equal to the width of the black matrix 33.

[0120] Multiple island electrodes 35b can also be arranged along the outer edge of the black matrix 33. Figure 9 It is along Figure 6 A cross-sectional diagram of the Y2-Y2' line. (See diagram below.) Figure 6 as well as Figure 9 As shown, multiple island electrodes 35b can also be arranged on the two outer edges of the optical opening sandwiched by the black matrix 33 in a pixel. Figure 10 It is along Figure 6 A cross-sectional view of line X2-X2' in the diagram. Figure 11 It is along Figure 6 A cross-sectional view of line X3-X3' in the diagram. (See diagram below.) Figure 6 , Figure 10 As shown, a portion of the preferred island electrode 35b has a portion that does not overlap with the optical opening of the pixel.

[0121] like Figure 6 , Figure 11As shown, the island-shaped electrodes 35b are preferably arranged alternately with the second linear electrode portions 34a and / or the third linear electrode portions 34b. By so arranging, as explained in the first embodiment, the electric field generated in the liquid crystal layer 20 is substantially parallel or substantially orthogonal to the absorption axis of the polarizing plate in plan view, and thus in the privacy mode, the front contrast ratio can be improved, and the contrast ratio from the oblique direction can be reduced, and the privacy performance can be improved. The direction of the above-described alternate arrangement can be, for example, a direction along the first direction Dl.

[0122] If the distance between the second linear electrode portion 34a and the island-shaped electrode 35b adjacent in plan view is set as d3, and the distance between the third linear electrode portion 34b and the island-shaped electrode 35b adjacent is set as d4, the distances d3 and d4 are preferably each 2.5 μm or more and 5 μm or less. By setting the distances d3 and d4 to the above-described range, the contrast ratio in the left-right direction in the privacy mode can be favorably suppressed. The more preferable lower limit of the distances d3 and d4 is 3 μm, and the more preferable upper limit is 4 μm. From the viewpoint of being able to improve the front contrast ratio in the privacy mode, the above-described distances d3 and d4 are more preferably 4 μm or less. The distances d3 and d4 are each a distance in a direction orthogonal to the second direction D2.

[0123] Figure 12 is a cross-sectional schematic view showing an example of arranging a dielectric layer (second dielectric layer) on the liquid crystal panel shown in Figure 11 is a cross-sectional schematic view showing an example of arranging a dielectric layer (second dielectric layer) on the liquid crystal panel shown in Figure 12 The liquid crystal panel 100D shown in has a second dielectric layer 51 between the third electrode 34 (the second linear electrode portion 34a, the third linear electrode portion 34b) and the liquid crystal layer 20, and between the fourth electrode 35 (the island-shaped electrode 35b) and the liquid crystal layer 20.

[0124] <Third Embodiment>

[0125] As the third embodiment, the control circuit, the display method, and the display viewing angle of a liquid crystal display device are explained below.

[0126] (Control Circuit)

[0127] The control circuit can switch a first display mode and a second display mode, the first display mode displaying a first image that can be observed from a narrow viewing angle range including a normal direction of a liquid crystal panel, and the second display mode being able to observe the first image from a wide viewing angle range including the above-described narrow viewing angle range.

[0128] In the present specification, the above first display mode is referred to as a privacy mode, and the above second display mode is referred to as a public mode. In the above narrow viewing angle range, it is preferable that the contrast be 5 or less when the liquid crystal panel is observed from the left-right direction (0° azimuth or 180° azimuth) at a certain polar angle. The above polar angle is, for example, 60° or more, more preferably 45° or more, and further preferably 30° or more, when the direction perpendicular to the surface of the liquid crystal panel is set as the polar angle 0°, and the direction horizontal to the surface of the liquid crystal panel is set as the polar angle 90°. The above wide viewing angle range refers to a range of polar angles greater than the polar angle of the above narrow viewing angle range.

[0129] Figure 13 is a block diagram schematically showing a display method of the first display mode and the second display mode in the third embodiment. As shown in Figure 13 the liquid crystal display device of the third embodiment has a liquid crystal panel and a control circuit 200. As the above liquid crystal panel, any one of the liquid crystal panels 100A to 100D exemplified in the first and second embodiments can be used.

[0130] The liquid crystal panel can also have a first electrode drive circuit 101 that applies a voltage to the first electrode 12, a second electrode drive circuit 102 that applies a voltage to the second electrode 14, and a third electrode drive circuit 103 that applies a voltage to the third electrode 34. The control circuit 200 can also have an image signal synthesis circuit 201, a display mode selection circuit 202, and a third electrode applied voltage switching circuit 203.

[0131] The control circuit 200 controls the application of a drive voltage to the third electrode 34 in the first display mode (privacy mode), and controls the application of a constant voltage to the third electrode 34 in the second display mode (public mode). The above constant voltage is an alternating voltage, and can be set to output a constant voltage regardless of the magnitude of the impedance of the third electrode 34. With respect to the third electrode 34, the above constant voltage is regarded as a common voltage, and the values of the voltages (alternating voltages) applied to the first electrode 12 and the second electrode 14 are determined. When the constant voltage is regarded as a common voltage Vcom = 0 V, for example, the Vcom voltage is applied to the first electrode 12, and an alternating voltage of Vcom ± a [a is a voltage value of 0 V or more, and the frequency is 60 Hz] is applied to the second electrode 14, whereby an edge electric field in which the direction of the electric field between the first electrode 12 and the second electrode 14 is reversed at a cycle of 60 Hz acts.

[0132] In the privacy mode of the liquid crystal panel, the drive voltage applied to the third electrode 34 is an alternating voltage having an effective value greater than the above constant voltage, and by applying the alternating voltage to the third electrode 34, a longitudinal electric field can be formed between the first electrode 12 (or the second electrode 14) to which the common voltage is applied. The above drive voltage can be, for example, an alternating voltage having an effective value of 3 to 7.5 V greater than the above constant voltage. Further, from the viewpoint of suppressing a phenomenon of afterimage (burn-in) of a residual display image at the time of the privacy mode, it is preferable that the drive voltage applied to the third electrode 34 be an alternating voltage of Vcom ± α [V] (α is a voltage value of 0 V or more, and the frequency is 120 Hz). This means that the frequency fl [Hz] of the drive voltage of the second electrode 14 and the frequency f2 [Hz] of the drive voltage of the third electrode 34 are in a relationship of 2 x fl = f2.

[0133] The image signal synthesis circuit 201 is inputted, for example, an original image signal 211 for displaying a desired image, and outputs an image signal 212 corresponding to the inputted original image signal 211 to the first electrode drive circuit 101 and the second electrode drive circuit 102.

[0134] The display mode selection circuit 202 is inputted a display mode switching signal 213 which switches the first display mode and the second display mode. In the case where the first display mode is selected, the display mode selection circuit 202 outputs a first display mode selection signal 214 to the third electrode application voltage switching circuit 203. In the case where the second display mode is selected, the display mode selection circuit 202 outputs a second display mode selection signal 215 to the third electrode application voltage switching circuit 203.

[0135] The third electrode application voltage switching circuit 203 inputs a drive voltage signal 216 or a constant voltage signal 217 to the third electrode drive circuit 103 in accordance with the inputted display mode selection signal, and switches the application of the drive voltage to the third electrode 34 and the application of the constant voltage. When the first display mode selection signal 214 is inputted from the display mode selection circuit 202, the third electrode application voltage switching circuit 203 outputs the drive voltage signal 216 to the third electrode drive circuit 103, and applies a prescribed alternating voltage to the third electrode 34. When the second display mode selection signal 215 is inputted from the display mode selection circuit 202, the third electrode application voltage switching circuit 203 outputs the constant voltage signal 217 to the third electrode drive circuit 103, and applies a prescribed constant voltage to the third electrode 34.

[0136] (Display method)

[0137] Next, an example of the display method of the first display mode and the second display mode will be described. First, in a voltage non-application state in which no voltage is applied to the liquid crystal layer, the liquid crystal molecules are horizontally oriented with respect to the active matrix substrate 10. In the present specification, "horizontal" means that the tilt angle (including a pre-tilt angle) of the liquid crystal molecules is 0° to 5°, preferably 0° to 3°, and more preferably 0° to 1° with respect to the surface of the active matrix substrate 10 or the color filter substrate 30. The tilt angle of the liquid crystal molecules means the angle at which the long axis of the liquid crystal molecules is inclined with respect to the surface of the active matrix substrate 10.

[0138] In the case of black display in the public mode, the control circuit 200 applies a prescribed alternating voltage as a constant voltage to the third electrode 34. The control circuit 200 controls the second electrode 14 and the first electrode 12 so as to apply a common voltage, which is 0 V with respect to the constant voltage, to both. Further, the common voltage applied to the second electrode 14 and the first electrode 12 can be the same as the constant voltage, or a voltage smaller than the threshold value of the liquid crystal molecules can be applied to the constant voltage. This state is also referred to as a voltage non-application state. In the voltage non-application state, no electric field that drives the liquid crystal molecules is generated in the liquid crystal layer 20, and thus the liquid crystal molecules are oriented in the initial orientation direction. Since the orientation direction of the liquid crystal molecules in the plane of the liquid crystal layer 20 does not change, the liquid crystal panel does not transmit light from the back surface and becomes black display. Further, black display means a display state in which the lowest luminance (0 gray scale) is obtained, and white display means a display state in which the highest luminance (255 gray scale) is obtained. The initial orientation direction is preferably parallel with respect to the active matrix substrate 10, and parallel with the absorption axis 61A of the first polarizing plate 61 or the absorption axis 62A of the second polarizing plate 62 when viewed in plan view.

[0139] In the case of white display in the public mode, for example, the control circuit applies a constant voltage (common voltage) to either one of the first electrode 12 and the second electrode 14 and an alternating voltage having a different effective value from the common voltage to the other one in a state in which the constant voltage is applied to the third electrode 34. An edge electric field is formed between the first electrode 12 and the second electrode 14, and on the other hand, unlike the privacy mode described later, the electric field in the thickness direction of the liquid crystal layer 20 is small. Thus, the liquid crystal molecules are oriented in parallel with respect to the active matrix substrate 10 in the electric field formed between the first electrode 12 and the second electrode 14, and the orientation direction is changed. The liquid crystal molecules rotate in the plane of the liquid crystal layer 20 and change from the initial orientation direction, and thus the long axis direction of the liquid crystal molecules forms an angle with the absorption axis 61A of the first polarizing plate and the absorption axis 62A of the second polarizing plate, and light from the back surface of the liquid crystal panel is transmitted and white display is performed.

[0140] When black display is performed in the privacy mode, the control circuit applies a drive voltage having an effective value different from the constant voltage to the third electrode, and applies a constant voltage (common voltage) to the second electrode 14 and the first electrode 12. A tilted electric field is formed between the third electrode 34 and the first electrode 12 and the second electrode 14. Liquid crystal molecules form an angle with respect to the active matrix substrate 10 by the tilted electric field.

[0141] Since the orientation direction of the liquid crystal molecules in the in-plane of the liquid crystal layer 20 does not change, the liquid crystal panel does not transmit light from the back surface, and the liquid crystal molecules form an angle with respect to the active matrix substrate, so that when the liquid crystal panel is observed from a wide viewing angle range, a display whiter than black display observed from a narrow viewing angle range is observed.

[0142] When white display is performed in the privacy mode, the control circuit 200 applies a constant voltage (common voltage) to either one of the first electrode 12 and the second electrode 14 and an alternating voltage having an effective value different from the common voltage to the other one, in a state where a drive voltage is applied to the third electrode 34. The drive voltage applied to the third electrode 34 is preferably different from the effective value of the alternating voltage applied to the first electrode 12 or the second electrode 14, and more preferably has a larger effective value than the alternating voltage applied to the first electrode 12 and the second electrode 14.

[0143] In addition, the frequency of the drive voltage applied to the third electrode 34 can be different from the frequency of the alternating voltage applied to the first electrode 12 or the second electrode 14, and the frequency of the drive voltage can be higher than the frequency of the alternating voltage applied to the first electrode 12 or the second electrode 14. The frequency of the drive voltage can be 60 Hz or 120 Hz, and the frequency of the alternating voltage applied to the first electrode 12 or the second electrode 14 can be 60 Hz. By setting the frequency of the drive voltage to 120 Hz, flicker can be reduced.

[0144] An edge electric field is formed between the first electrode 12 and the second electrode 14, and a tilted electric field is formed with respect to the thickness direction of the liquid crystal layer 20 between the third electrode 34 and the first electrode 12 or between the third electrode 34 and the second electrode 14. As a result, an electric field in which the edge electric field and the tilted electric field are combined is formed in the liquid crystal layer 20, so that the liquid crystal molecules change the orientation potential while forming an angle with respect to the active matrix substrate 10, and white display is performed. Since the liquid crystal molecules form an angle with respect to the active matrix substrate, the first image can be observed from a narrow viewing angle range, and on the other hand, when the liquid crystal panel is observed from a wide viewing angle range, an image change in which the contrast becomes extremely low or the like is obtained, and the first image is not easily observed.

[0145] In privacy mode, when displaying black and white, grayscale display is performed while a constant voltage is applied to the third electrode 34 as described above. In conventional liquid crystal display devices, when a voltage is applied to the electrodes provided on the color filter substrate, the black matrix provided on the color filter substrate is charged, and an electric field deviating from the absorption axis of the polarizer is formed between the charged black matrix and the electrodes on the active matrix substrate side. If such an electric field is generated, during black display in privacy mode, the orientation of liquid crystal molecules may be locally disordered, resulting in light leakage. In the first embodiment, by configuring the fourth electrode in a floating state, the electric field from the third electrode 34 toward the black matrix 33 can be blocked or the electric field strength can be reduced, suppressing the generation of an electric field deviating from the absorption axis of the polarizer between the black matrix 33 and the electrodes on the active matrix substrate 10 side, thus preventing the aforementioned light leakage.

[0146] The white display in privacy mode and the white display in public mode are switched by applying voltage to the third electrode. Similarly, the black display in privacy mode and the black display in public mode are switched by applying voltage to the third electrode. The same applies to intermediate grayscale display.

[0147] In the liquid crystal display device according to the embodiment, as described above, high privacy can be obtained when viewing the liquid crystal panel from the left and right directions by switching from the second display mode (public mode) to the first display mode (privacy mode). Furthermore, the left and right directions refer to the 0° and 180° orientations, respectively, when the right-hand direction of the liquid crystal panel displaying the desired image is set to 0° and the angle increases counterclockwise.

[0148] (View control display)

[0149] In addition to switching display modes as described above, it can also be combined with the soft viewing angle control function described later. Furthermore, the soft viewing angle control function refers to the function of displaying specific viewing angle control via software. For example, the aforementioned control circuit can also be driven by software to display a viewing angle control pattern. Figures 14-16 This illustrates an example of a method for displaying images using soft perspective control. Figure 14 This is a plan view illustrating an example of a display unit in a liquid crystal panel. Figure 15 This is a plan view illustrating an example of a color element in a color display scenario using a soft viewing angle control function. Figure 16 This is a block diagram schematically illustrating the display method in the case of displaying a viewing angle control pattern in the third embodiment.

[0150] like Figure 14As shown, the liquid crystal panels 100A to 100D (hereinafter, also simply referred to as liquid crystal panels) have a plurality of display units 72 that display an image by a soft viewing angle control function. The display unit 72 includes a pair of pixels that are configured adjacent to each other, and are composed of a first pixel 70 selected from an odd-numbered row and a second pixel 71 selected from an even-numbered row. The first pixel 70 and the second pixel 71 can be captured as one pixel as shown in Figure 1 and Figure 6 As shown, the liquid crystal panels 100A to 100D (hereinafter, also simply referred to as liquid crystal panels) have a plurality of display units 72 that display an image by a soft viewing angle control function. The display unit 72 includes a pair of pixels that are configured adjacent to each other, and are composed of a first pixel 70 selected from an odd-numbered row and a second pixel 71 selected from an even-numbered row. The first pixel 70 and the second pixel 71 can be captured as one pixel as shown in Figure 15 As shown, the liquid crystal panels 100A to 100D (hereinafter, also simply referred to as liquid crystal panels) have a plurality of display units 72 that display an image by a soft viewing angle control function. The display unit 72 includes a pair of pixels that are configured adjacent to each other, and are composed of a first pixel 70 selected from an odd-numbered row and a second pixel 71 selected from an even-numbered row. The first pixel 70 and the second pixel 71 can be captured as one pixel as shown in

[0151] In the case of color display, the above-described liquid crystal panel preferably includes a red display unit 72R including the first red pixel 70R and the second red pixel 71R, a green display unit 72G including the first green pixel 70G and the second green pixel 71G, and a blue display unit 72B including the first blue pixel 70B and the second blue pixel 71B. The color element 73 can also include the red display unit 72R, the green display unit 72G, and the blue display unit 72B. The first red pixel 70R and the second red pixel 71R respectively overlap the red color filter 32R at the optical opening portion. The first green pixel 70G and the second green pixel 71G respectively overlap the green color filter 32G at the optical opening portion. The first blue pixel 70B and the second blue pixel 71B respectively overlap the blue color filter 32B at the optical opening portion.

[0152] As a method of displaying an image by the soft viewing angle control function, for example, when the data value of the luminance of the original image that is intended to be displayed as a first image is set as Data1, Data1 is divided into two data values Data2 and Data3 that are equal to each other, a data value of Data1 + Data2 is input to either the first pixel 70 or the second pixel 71, and a data value of Data1 - Data3 is input to the other. In the case of observing the liquid crystal panel from a narrow viewing angle range, the luminance of the first pixel 70 and the luminance of the second pixel 71 are spatially averaged, and the luminance of the original image is visually confirmed, on the other hand, in the case of observing from a wide viewing angle range, the luminance of Data1 + Data2 or the luminance of Data1 - Data3 is visually confirmed.

[0153] The following describes a display method when a soft viewing angle control pattern is displayed. Figure 16 The control circuit 200 inputs different image signals to the first pixel and the second pixel in a manner that a second image different from the first image is observed from the wide viewing angle range in the first display mode described above. This display method is also called a soft viewing angle control function. Display based on the soft viewing angle control function can further improve privacy by being combined with the first display mode (privacy mode), and thus, it is preferable that the viewing angle control pattern database 205 (hereinafter, database 205) outputs a viewing angle control pattern image signal 220 to the image signal synthesizing circuit 201 when the first display mode selection signal 214 is input from the display mode selection circuit 202.

[0154] As shown in FIG. 8, the control circuit 200 can also have a database 205 in which information about a viewing angle control pattern is stored. When a viewing angle control display switching signal 219 is input, the database 205 outputs a viewing angle control pattern image signal 220 to the image signal synthesizing circuit 201. The image signal synthesizing circuit 201 outputs an image signal 212 in which the original image signal 211 and the viewing angle control pattern image signal 220 are synthesized to the first electrode drive circuit 101 and the second electrode drive circuit 102. Figure 16 For example, when a common voltage is applied to the second electrode 14 by the second electrode drive circuit 102, different voltages are applied to the first electrode 12 corresponding to the first pixel 70 and the second pixel 71 by the first electrode drive circuit 101, respectively, to observe the second image from the wide viewing angle range. In this case, it is preferable that the first electrode 12 is provided for each pixel. On the other hand, when a common voltage is applied to the first electrode 12 by the first electrode drive circuit 101, different voltages are applied to the second electrode 14 corresponding to the first pixel 70 and the second pixel 71 by the second electrode drive circuit 102, respectively, to observe the second image from the wide viewing angle range.

[0155] The second image described above is preferably a viewing angle control pattern. The viewing angle control pattern described above is a display image in which the first image described above is overlaid and displayed and the first image is not easily visually confirmed. By displaying the viewing angle control pattern, privacy can be further improved. There is no particular limitation on the viewing angle control pattern described above, and a geometric pattern such as a stripe pattern, a checkered pattern, a character, an image, or the like can be displayed.

[0156] <Fourth Embodiment>

[0157]

[0158] ​The liquid crystal display device according to the fourth embodiment has a backlight on the back side of the liquid crystal panel. The backlight has a light source and a light-shielding louver disposed on the liquid crystal panel side of the light source. The control circuit controls the backlight to make the brightness of the backlight in the first display mode lower than the brightness of the backlight in the second display mode. As the liquid crystal panel, any one of the liquid crystal panels 100A to 100D exemplified in the first and second embodiments can be used.

[0159] In the fourth embodiment, a backlight source comprising a light source and light-shielding louvers disposed on the side of the liquid crystal panel of the light source is used as the backlight source. By using a backlight source with light-shielding louvers, the brightness in the normal direction can be relatively increased, and the directivity of the backlight source can be improved. The backlight source with the aforementioned light-shielding louvers can be a known backlight source, or, for example, a backlight source disclosed in Patent Document 3.

[0160] Figure 17 This is an exploded perspective view schematically illustrating a backlight source equipped with the light-blocking louvers used in the fourth embodiment. The backlight source equipped with the aforementioned light-blocking louvers can be a side-lit type, for example, such as... Figure 17 As shown, the light guide plate 310 and a light source 311 disposed on the side of the light guide plate 310 may also be included, and a light-shielding louver 312 may be provided on the front side (liquid crystal panel side) of the light guide plate 310. A reflective sheet 313 may be disposed on the back side of the light guide plate 310, and a prism sheet 314, a diffuser sheet 315, etc. may be disposed between the light guide plate 310 and the light-shielding louver 312. The light source 311 may be disposed on at least one of the opposite sides of the light guide plate 310, but it may also be disposed on both sides. Figure 17 The image shows an example of the light source 311 being arranged along the 0°-180° orientation of the liquid crystal panel, but it can also be arranged along the 90°-270° orientation of the liquid crystal panel.

[0161] The light-shielding louvers 312 preferably shield the light emitted from the light guide plate according to the incident angle. For example, as the light-shielding louvers, there can be mentioned light-shielding louvers in which a light-transmitting layer 312a that transmits light and a light-absorbing layer 312b that absorbs light are alternately arranged in a specific period, as disclosed in Patent Document 3. The arrangement period of the light-transmitting layer 312a and the light-absorbing layer 312b can be, for example, 100 to 150 μm. The light-transmitting layer 312a and the light-absorbing layer 312b can be arranged in a linear shape in plan view, and the extending direction of the light-transmitting layer 312a and the light-absorbing layer 312b is preferably at an angle of 0 to 10° with respect to the 90°-270° azimuth of the liquid crystal panel, or can be parallel to the 90°-270° azimuth (the angle is 0°). The light-transmitting layer 312a can be formed of a resin having light-transmitting properties, and the light-absorbing layer 312b can be formed of a black pigment or a resin containing a dye. The total light transmittance of the light-absorbing layer 312b is preferably 5% or less, and the total light transmittance of the light-transmitting layer 312a is preferably 80% or more.

[0162] The liquid crystal display device according to the fourth embodiment can more effectively improve the privacy in the privacy mode by coordinating the luminance of the backlight with the display mode. Figure 18 is a block diagram schematically showing a display method in the first display mode and the second display mode in the fourth embodiment. Figure 19 is a block diagram schematically showing a display method in a case where a viewing angle control pattern is displayed in the fourth embodiment.

[0163] The control circuit 200 controls so that the luminance of the backlight 300 in the above-mentioned first display mode is lower than the luminance of the backlight 300 in the above-mentioned second display mode. As shown in Figure 18 and Figure 19 The control circuit 200 can further include a luminance modulation circuit 204 of the backlight, as shown. In addition, the backlight 300 can include a backlight drive circuit 301.

[0164] When the first display mode selection signal 214 is input from the display mode selection circuit 202, the luminance modulation circuit 204 outputs a luminance modulation signal 218 to the backlight drive circuit 301 and adjusts so that the luminance of the backlight 300 is lowered. When the second display mode selection signal 215 is input from the display mode selection circuit 202, the luminance modulation circuit 204 outputs a luminance modulation signal 218 to the backlight drive circuit 301 and adjusts so that the luminance of the backlight 300 is increased.

[0165] The luminance of the backlight 300 can be adjusted so that the luminance of the liquid crystal panel at the time of white display when viewed from the normal direction is, for example, 100 to 300 nit in the first display mode and 300 to 500 nit in the second display mode.

[0166] [EMBODIMENT]

[0167] The effects of the present invention will be illustrated below with examples and comparative examples, but the present invention is not limited to these examples.

[0168] (Example 1)

[0169] Example 1 is a specific example of the first embodiment, and the plan view is consistent with... Figure 1 The same. The liquid crystal panel used in Example 1 has the same... Figure 5 The structure is the same as that of the liquid crystal panel 100B with a second dielectric layer 51 shown. The active matrix substrate 10 has an FFS-type electrode structure, and the first electrode 12 is a full-surface electrode without an opening. The second electrode 14 is configured to be disposed in each pixel, having three first linear electrode portions 14a with a width of 2.5 μm, and an opening 14b with a width of 3.5 μm between the first linear electrode portions 14a. The liquid crystal molecules are positive liquid crystal materials. Regarding the color filter substrate 30, the thickness of the color filter is 2.3 μm, the thickness of the first dielectric layer 50 is 2 μm, and the thickness of the second dielectric layer 51 is 2 μm. The angle θ1 formed by the extension direction (first direction D1) of the first linear electrode portion 14a and the extension direction (second direction D2) of the second linear electrode portion 34a and the third linear electrode portion 34b of the third electrode is 80°. Regarding the size of a pixel, the horizontal width along the second direction is 25μm, and the vertical width along the direction orthogonal to the second direction is 75μm.

[0170] Regarding the third electrode 34, in Embodiment 1, the number of third linear electrode portions 34b overlapping the optical opening of one pixel is three. The width W34a of the third linear electrode portion 34b is set to 5 μm, and the distance between the second linear electrode portion 34a and the third linear electrode portion 34b, as well as between adjacent third linear electrode portions 34b, is set to 5 μm.

[0171] When viewed from above, fourth linear electrode portions 35a are respectively disposed between the second linear electrode portion 34a and the third linear electrode portion 34b, and between adjacent third linear electrode portions 34b, with four fourth linear electrode portions 35a disposed per pixel. The width W35a of the fourth linear electrode portion 35a included in the fourth electrode is 5μm, and the distance between adjacent fourth linear electrode portions 35a is 5μm. In addition, the distances d1 and d2 between the fourth linear electrode portion 35a and the adjacent second linear electrode portions 34a and third linear electrode portions 34b are both 3μm.

[0172] ITO can be used as the first electrode 12, the second electrode 14, the third electrode 34, and the fourth electrode 35. For example, silicon oxide can be used as the first insulating layer 13, and an acrylic resin can be used as the first dielectric layer 50. The black matrix is composed of a black resin, and has a resistivity of 1.0 x 10 10 ~1.0 x 10 13 (Ω-cm).

[0173] (Second Embodiment)

[0174] Example 2 is a specific example of the first embodiment, and has the same configuration as Example 1 except that the liquid crystal panel does not have the second dielectric layer 51. The liquid crystal panel used in Example 2 has the same structure as the liquid crystal panel 100A shown in FIG. 1. Figure 1 , Figure 4 and the like. The liquid crystal panel used in Example 2 has the same structure as the liquid crystal panel 100A shown in FIG. 1.

[0175] (Example 3)

[0176] Example 3 is a specific example of the second embodiment, and the fourth electrode has the island-shaped electrodes 35b (see FIG. 3 and the like). Example 3 has the same configuration as Example 1 except that the fourth electrode has the island-shaped electrodes 35b instead of the linear electrodes, and that the liquid crystal panel does not have the second dielectric layer 51. Regarding the third electrode 34, in Example 3, the number of the third linear electrode portions 34b overlapping with the optical opening portion of one pixel is three, like Example 1. Figure 6 Figure 11 Regarding the third electrode 34, in Example 3, the number of the third linear electrode portions 34b overlapping with the optical opening portion of one pixel is three, like Example 1.

[0177] In Example 3, for one pixel, for the two outer edges of the black matrix 33 sandwiching the optical opening portion, four island-shaped electrodes 35b in total are arranged between the second linear electrode portion 34a and the third linear electrode portion 34b, and between the adjacent third linear electrode portions 34b, respectively.

[0178] The width W35b of the island-shaped electrode 35b included in the fourth electrode is set to 5 μm, and the distance between the adjacent island-shaped electrodes 35b is set to 5 μm. In addition, the distances d3 and d4 of the island-shaped electrode 35b from the adjacent second linear electrode portion 34a and third linear electrode portion 34b are both 3 μm.

[0179] (Comparative Example 1)

[0180] Figure 20 is a cross-sectional view of the liquid crystal panel of Comparative Example 1, and corresponds to the X1-X1' line of Figure 1 . As shown in Figure 20 ​In the liquid crystal panel 1100 of Comparative Example 1, the color filter substrate 30 has the second substrate 31, the black matrix 33, the color filter 32 (32G), and the first dielectric layer 50 in this order. Comparative Example 1 has no electrode on the color filter substrate 30 side. The thickness of the color filter is 2.3 μm, and the thickness of the first dielectric layer 50 is 2 μm. The active matrix substrate 10 has the same structure as that of Example 1, and has an electrode structure of the FFS type having the first electrode 12 and the second electrode 14 stacked with the first insulating layer 13 interposed therebetween.

[0181] <Simulation of contrast ratio>

[0182] The contrast ratio was simulated for 0° to 360° azimuth for Examples 1 to 3 and Comparative Example 1. In the simulation of the contrast ratio, the LCD host 3D (manufactured by Sumitec Corporation) was used, and the contrast ratio was simulated when the liquid crystal panel was observed from 0° azimuth to 360° azimuth. The azimuth at which the value of the contrast ratio is high can be said to be an azimuth at which visual recognition is good. The contrast ratio (CR) is represented by the following formula (1). CR = luminance at white display (255 gradation) / luminance at black display (0 gradation) (1)

[0183] For Examples 1 to 3, the contrast ratio was simulated when white display was performed in the public mode and the privacy mode, and for Comparative Example 1, the contrast ratio was simulated when white display was performed. Hereinafter, the value of the alternating voltage applied to the first electrode and the second electrode, and the value of the driving voltage applied to the third electrode are values in a case where the constant voltage to be applied to the third electrode is set to the common voltage (0 V) in the public mode.

[0184] In the public mode, a constant voltage (common voltage) was applied to the third electrode in Examples 1 to 3. As the constant voltage, a fixed voltage of 0 V was applied. In the privacy mode, a case where an alternating voltage of 7.5 V with respect to the constant voltage was applied to the third electrode in Example 1 and Example 2, and a case where an alternating voltage of 5 V with respect to the constant voltage was applied to the third electrode in Example 3 were simulated. White display was performed by applying the common voltage (0 V) to the first electrode 12 and applying an alternating voltage of 6.5 V of the constant voltage to the second electrode 14 in both the public mode and the privacy mode. In addition, the frequency of the third electrode was 120 Hz, and the frequency of the second electrode 14 was 60 Hz. In Comparative Example 1, white display was performed by applying an alternating voltage of the common voltage (0 V) to the first electrode 12 and applying 6.5 V to the second electrode 14.

[0185] Figure 21A table summarizing the simulation results of the contrast ratios of Examples 1 to 3 and Comparative Example 1. In the table, "front" of CR (contrast ratio) indicates the front contrast ratio, which is the contrast ratio when the liquid crystal panel is observed from the front (normal direction). "Polar angle 45°" is the contrast ratio when the liquid crystal panel is observed from the polar angle 45° in the 0° direction or the 180° direction.

[0186] As shown in Figure 21 any one of Example 1 in which the floating electrode (fourth electrode) includes the linear electrode portion and Example 2, and Example 3 in which the floating electrode (fourth electrode) includes the island-shaped electrode, it is possible to switch the public mode and the privacy mode, and in the privacy mode, the contrast ratio in the left-right direction at the polar angle 45° (hereinafter, the contrast ratio at the polar angle 45°) is sufficiently suppressed, and a high front contrast ratio is obtained. In addition, it is confirmed that in Example 1 having the second dielectric layer 51, the mode can be switched equally in Example 2 not having the second dielectric layer 51, and in the privacy mode, the contrast ratio at the polar angle 45° is sufficiently suppressed, and a high front contrast ratio is obtained. On the other hand, Comparative Example 1 cannot reduce the contrast ratio in the left-right direction because it does not have an electrode on the color filter substrate side, and cannot achieve the privacy mode.

[0187] Figure 22 is a cross-sectional schematic view showing the electric field of the liquid crystal panel of Example 1. It is considered that the black matrix is charged by applying a voltage to the third electrode, but as shown in Figure 22 , it is considered that by providing the fourth electrode in the floating state on the color filter substrate 30, the electric field from the third electrode 34 toward the black matrix 33 can be shielded or the electric field strength can be reduced, and thus the generation of the electric field deviated from the absorption axis of the polarizing plate between the black matrix 33 and the electrode on the active matrix substrate 10 side can be suppressed. With respect to Examples 2 and 3, the generation of the above-described electric field due to the charging of the black matrix can also be suppressed. As a result, the liquid crystal display device of Examples 1 to 3 can prevent the generation of light leakage.

[0188] <Measurement of luminance in the privacy mode and the public mode>

[0189] With respect to Comparative Example 1, Example 2, and Example 3, the luminance when the display surface is observed from the normal direction (front) at the time of black display (0 gray scale) and white display (255 gray scale) was measured. The measurement of the luminance was performed using "SR-ULIR" manufactured by Topcon Techno Corporation. The results are shown in Table 1 below. In Table 1 below, the luminance at the time of white display of Example 2, Example 3 is the luminance when the luminance at the time of white display of Comparative Example 1 is set to 100%, and the luminance at the time of black display of Example 2, Example 3 is the luminance when the luminance at the time of black display of Comparative Example 1 is set to 100%.

[0190] [Table 1]

[0191]

[0192] According to the results of Table 1, it was confirmed that the example 3 in which the floating electrode (fourth electrode) contains island-shaped electrodes can improve the transmittance at the time of white display, as compared with the example 2 in which the floating electrode (fourth electrode) contains linear electrodes.

[0193] (Example 4)

[0194] The example 4 is a specific example of the second embodiment, and has a backlight in which a light shielding shutter is used as a backlight. The liquid crystal panel of the example 4 has the same structure as the liquid crystal panel of the example 3 except that the number of the third linear electrode portions 34b included in the third electrode, the number of the island-shaped electrodes 35b included in the fourth electrode, and the number and the width W35b of the island-shaped electrodes 35b are changed to 5.3 μm.

[0195] Regarding the third electrode 34, the number of the third linear electrode portions 34b overlapping with the optical opening portion of one pixel is two in the example 4. The width W34a of the third linear electrode portion 34b is 5 μm, and the distance between the second linear electrode portion 34a and the third linear electrode portion 34b and the distance between the adjacent third linear electrode portions 34b is 11.3 μm.

[0196] In the example 4, for one pixel, for the two outer edges of the black matrix 33 sandwiching the optical opening portion, three island-shaped electrodes 35b in total are disposed between the second linear electrode portion 34a and the third linear electrode portion 34b and between the adjacent third linear electrode portions 34b, respectively.

[0197] The width W35b of the island-shaped electrode 35b included in the fourth electrode is set to 5 μm, and the distance between the adjacent island-shaped electrodes 35b is set to 11 μm. In addition, the distances d3 and d4 of the island-shaped electrode 35b from the adjacent second linear electrode portion 34a and the third linear electrode portion 34b are both 3 μm.

[0198] In the public mode, a constant voltage (common voltage) is applied to the third electrode, and in the privacy mode, as a driving voltage, an alternating voltage of 3 V (120 Hz) with respect to the above constant voltage is applied to the third electrode. As the above constant voltage, a fixed voltage of 0 V is applied. In both the public mode and the privacy mode, the common voltage (0 V) is applied to the first electrode 12, and an alternating voltage of 5 V (60 Hz) of the above constant voltage is applied to the second electrode 14, and thus white display is performed.

[0199] In Example 4, the backlight brightness is controlled such that it is lower in the first display mode (privacy mode) than in the second display mode (public mode). In public mode, the backlight brightness is adjusted so that the brightness of the liquid crystal panel in the normal direction (polar angle 0°) is 500 nits. The brightness at a polar angle ±45° in public mode is 15 nits. In privacy mode, the backlight brightness is adjusted so that the brightness of the liquid crystal panel in the polar angle 0° is 100 nits. The brightness at a polar angle ±45° in privacy mode is 3 nits. Furthermore, the brightness at +45° is the brightness when the liquid crystal panel is viewed from a 0° position at a polar angle of 45°, and the brightness at -45° is the brightness when the liquid crystal panel is viewed from a 180° position at a polar angle of 45°.

[0200] Figure 23 This is a cross-sectional schematic diagram illustrating the case in Example 4 where the backlight is linked and the display is performed in a common mode. Figure 24 This is a cross-sectional schematic diagram illustrating the case in Example 4 where the backlight is activated and the display is in privacy mode. Figure 25 This is a graph showing the contrast of the front view and the polar angle of 45° in Example 4. Figures 23-25 In the figure, the opposing voltage (Vc) on the horizontal axis is the voltage applied to the third electrode.

[0201] If a backlight with blackout blinds is used, then... Figure 23 and Figure 24 As shown, the brightness along the normal direction (polar angle 0°) is higher than the brightness at the polar angle ±45°. As described above, by controlling the backlight brightness in privacy mode to be lower than that in public mode, privacy performance can be improved while maintaining frontal visual recognizability.

[0202] like Figure 25 As shown, when a constant voltage (0V) is applied to the third electrode, it functions as a common mode, with a front contrast ratio of 1885 and a contrast ratio of 82 at a 45° polar angle. On the other hand, if a driving voltage is applied to the third electrode, it functions as a privacy mode, with a front contrast ratio of 1983 and a contrast ratio of 4 at a 45° polar angle.

[0203] Figure 26 This is a graph showing the brightness of the front side of Embodiment 4 and when displayed in white at a polar angle of 45°. Figure 27 This is a graph showing the brightness of the front side of Embodiment 4 and when displayed in black at a 45° polar angle. Using Figure 26 The brightness of the liquid crystal display device when displaying white was studied. The brightness when viewed from the front is about 1.4 times that at a polar angle of 45°.

[0204] use Figure 27The luminance at the black display time when viewed from the front is about 100 times the luminance at the polar angle of 45°. As shown in Figure 27 by providing the floating electrode, even if the opposing voltage is increased, the increase in the luminance at the black display time when viewed from the front can be suppressed, and only the luminance at the black display time at the polar angle of 45° is increased. Further, by adjusting the luminance of the backlight with the light-shielding louvers, as shown in Figure 25 the contrast ratio from the oblique direction can be reduced while maintaining the front contrast ratio at 1000 or more, and the privacy in the privacy mode can be improved.

[0205] BRIEF DESCRIPTION OF DRAWINGS

[0206] 1: Gate wire

[0207] 2: Source wire

[0208] 3: TFT

[0209] 10: Active matrix substrate

[0210] 11: First substrate

[0211] 12: First electrode

[0212] 13: First insulating layer

[0213] 14: Second electrode

[0214] 14a: First linear electrode portion

[0215] 14b: Opening

[0216] 20: Liquid crystal layer

[0217] 30: Color filter substrate

[0218] 31: Second substrate

[0219] 32: Color filter

[0220] 32B: Blue color filter

[0221] 32G: Green color filter

[0222] 32R: Red color filter

[0223] 33: Black matrix

[0224] 34: Third electrode

[0225] 34a: Second linear electrode portion

[0226] 34b: Third linear electrode portion

[0227] 35: Fourth electrode (floating electrode)

[0228] 35a: fourth linear electrode portion

[0229] 35b: island-shaped electrode

[0230] 50: first dielectric layer

[0231] 51: second dielectric layer

[0232] 61: first polarizing plate

[0233] 61A: first polarizing plate absorption axis

[0234] 62: second polarizing plate

[0235] 62A: second polarizing plate absorption axis

[0236] 70: dye (first dye)

[0237] 70B: first blue pixel

[0238] 70G: first green pixel

[0239] 70R: first red pixel

[0240] 71: second pixel

[0241] 71B: second blue pixel

[0242] 71G: second green pixel

[0243] 71R: second red pixel

[0244] 72: display unit

[0245] 72B: blue display unit

[0246] 72G: green display unit

[0247] 72R: red display unit

[0248] 73: color element

[0249] 100A, 100B, 100C, 100D, 1100: liquid crystal panel

[0250] 101: first electrode drive circuit

[0251] 102: second electrode drive circuit

[0252] 103: third electrode drive circuit

[0253] 200: control circuit

[0254] 201: image signal synthesis circuit

[0255] 202: display mode selection circuit

[0256] 203: third electrode voltage application switching circuit

[0257] 204: brightness modulation circuit

[0258] 205: viewing angle control pattern database

[0259] 211: original image signal

[0260] 212: image signal

[0261] 213: display mode switching signal

[0262] 214: first display mode selection signal

[0263] 215: second display mode selection signal

[0264] 216: drive voltage signal

[0265] 217: constant voltage signal

[0266] 218: brightness modulation signal

[0267] 219: viewing angle control display switching signal

[0268] 220: viewing angle control pattern image signal

[0269] 300: backlight

[0270] 301: backlight drive circuit

[0271] 310: light guide plate

[0272] 311: light source

[0273] 312: light blocking louver

[0274] 312a: light transmission layer

[0275] 312b: light absorption layer

[0276] 313: reflective sheet

[0277] 314: prismatic sheet

[0278] 315: diffusing sheet

Claims

1. A liquid crystal display device, comprising a liquid crystal panel having a plurality of pixels arranged in a matrix and a control circuit, characterized in that, The liquid crystal panel sequentially comprises an active matrix substrate, a liquid crystal layer, and a color filter substrate. The active matrix substrate sequentially comprises: a first substrate; a first electrode; and a first insulating layer; And a second electrode disposed in each of the pixels and including a first linear electrode portion extending along a first direction. The color filter substrate includes: a second substrate; a black matrix disposed between the plurality of pixels; a color filter; a third electrode comprising a plurality of second linear electrode portions; and a fourth electrode serving as a floating electrode. The third electrode and the fourth electrode are disposed between the black matrix and the liquid crystal layer. The second linear electrode portion extends in a second direction intersecting the first direction and overlaps with the portion of the black matrix extending in the second direction. The fourth electrode, when viewed from above, is positioned between the plurality of second linear electrode portions and overlaps with at least a portion of the black matrix. The control circuit switches between applying a driving voltage and applying a constant voltage to the third electrode.

2. The liquid crystal display device as claimed in claim 1, characterized in that, The fourth electrode is disposed on the same layer as the third electrode.

3. The liquid crystal display device as described in claim 1 or 2, characterized in that, The third electrode further includes a third linear electrode portion disposed between the plurality of second linear electrode portions. The third linear electrode portion is configured to extend in the second direction when viewed from above and overlap with the optical opening of the pixel.

4. The liquid crystal display device as described in claim 3, characterized in that, The fourth electrode includes a fourth linear electrode portion that extends along the second direction and is disposed overlapping the optical opening of the pixel. The fourth linear electrode is disposed between the plurality of second linear electrode portions and the third linear electrode portion.

5. The liquid crystal display device as claimed in claim 3, characterized in that, The fourth electrode comprises multiple island-shaped electrodes that are independent of each other when viewed from above. The plurality of island electrodes are disposed between the plurality of second linear electrode portions and the third linear electrode portion.

6. The liquid crystal display device according to any one of claims 1 to 5, characterized in that, A dielectric layer is provided between the third electrode and the liquid crystal layer.

7. The liquid crystal display device according to any one of claims 1 to 6, characterized in that, The third electrode is formed of a transparent conductive material.

8. The liquid crystal display device according to any one of claims 1 to 7, characterized in that, The active matrix substrate has gate wiring and source wiring arranged in a manner that intersects with the gate wiring. The gate wiring extends along the second direction.

9. The liquid crystal display device as claimed in claim 8, characterized in that, Each of the plurality of second linear electrode portions overlaps with the gate wiring when viewed from above.

10. The liquid crystal display device according to any one of claims 1 to 9, characterized in that, The control circuit can switch between a first display mode and a second display mode. The first display mode displays a first image that can be viewed from a narrow viewing angle that includes the normal direction of the liquid crystal panel, while the second display mode allows the first image to be viewed from a wide viewing angle that includes the narrow viewing angle. In the first display mode, the control circuit controls the application of the driving voltage to the third electrode, and in the second display mode, it controls the application of the constant voltage to the third electrode.

11. The liquid crystal display device as claimed in claim 10, characterized in that, A backlight is provided on the back of the LCD panel. The backlight includes a light source and light-shielding louvers disposed on the side of the liquid crystal panel of the light source. The control circuit controls the backlight brightness in the first display mode to be lower than the backlight brightness in the second display mode.

Images