Display device

Abstract

To provide a display device with a border between a display area and a frame area less noticeable even when a liquid crystal panel is displayed in black.SOLUTION: A display device comprises a liquid crystal panel, a front plate disposed on an observer side of the liquid crystal panel, and a backlight disposed on a back surface of the liquid crystal panel. The liquid crystal panel has a display area and a frame area disposed around the display area in a plan view. The front plate includes a design layer superimposed with the display area in a plan view, transmits at least some of light made incident from the liquid crystal panel and reflects at least some of light made incident from the observer side. The backlight, in a plan view, includes a third area superimposed with the display area of the liquid crystal panel and a fourth area superimposed with the display area of the liquid crystal panel and disposed around the third area, and during lighting of the backlight, the brightness of the fourth area is 50% or less of that of the third area.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a display device. [Background technology]

[0002] In recent years, for display devices that display a desired image when the display screen is turned on, studies have been conducted on ways to enhance the design by making the display panel, such as a liquid crystal panel, less noticeable when the panel is turned off, so that the panel blends in with the surrounding components and housing, etc. As a method for making the display screen less noticeable when the panel is turned off, for example, a method has been studied in which a printed material containing an interference pigment or a semi-transparent member, such as a screen or decorative film that transmits part of the light, is placed on the front side of the display panel (for example, Patent Documents 1 to 3, etc.).

[0003] Patent Document 1 discloses a printed matter comprising: a base film; a first color pattern layer formed on the base film and composed of a plurality of first color dots; a second color pattern layer formed on the first color pattern layer and composed of a plurality of second color dots; and a third color pattern layer formed on the second color pattern layer and composed of a plurality of third color dots, wherein each of the first color dots includes a first color binder and a plurality of first color pigment chips dispersed inside the first color binder, each of the second color dots includes a second color binder and a plurality of second color pigment chips dispersed inside the second color binder, each of the third color dots includes a third color binder and a plurality of third color pigment chips dispersed inside the third color binder, and each of the first color pigment chips, second color pigment chips, and third color pigment chips are any one of a red interference pigment, a green interference pigment, and a blue interference pigment.

[0004] Patent Document 2 discloses a display device having a display that is fitted into an attachment portion and emits display light to the outside when lit, characterized in that the front of the display is covered with a screen having a large number of fine holes that can transmit the display light, and the surface of the screen is set to the same color and pattern as the attachment portion around the display.

[0005] Patent Document 3 discloses a display device with a decorative sheet, comprising a display device having a display surface and a decorative sheet arranged opposite the display surface, wherein the decorative sheet has a picture portion and a plurality of transmissive portions which are non-forming portions of the picture portion, has an aperture ratio of 5% or more and 50% or less, and the transmissive portions are formed so that the distance between adjacent transmissive portions is 40 μm or more and 140 μm or less, and wherein the display device is a dot-matrix liquid crystal display, and discloses a display device with a decorative sheet, wherein the pitch of the transmissive portions is larger than the pixel pitch of the display surface. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5725581 [Patent Document 2] JP 2001-331132 A [Patent Document 3] Patent No. 6696014 Summary of the Invention [Problem to be solved by the invention]

[0007] In a display device equipped with a liquid crystal panel and a backlight on the rear side of the liquid crystal panel, even when black is displayed in the display area, the liquid crystal panel transmits a small amount of backlight light even in the black display state, so the black in the display area can appear slightly brighter than pure black (floating black).

[0008] The present invention has been made in consideration of the above-mentioned current situation, and aims to provide a display device in which the boundary between the display area and the frame area is not noticeable even when the liquid crystal panel is set to black display. [Means for solving the problem]

[0009] (1) One embodiment of the present invention is a display device comprising a liquid crystal panel, a front panel arranged on the observer side of the liquid crystal panel, and a backlight arranged on the rear side of the liquid crystal panel, wherein the liquid crystal panel has, in a planar view, a display area and a frame area arranged around the display area, the front panel includes a design layer overlapping with the display area in a planar view, and transmits at least a portion of the light incident from the liquid crystal panel and reflects at least a portion of the light incident from the observer side, the backlight includes a third area overlapping with the display area of ​​the liquid crystal panel in a planar view, and a fourth area overlapping with the display area of ​​the liquid crystal panel and arranged around the third area, and when the backlight is turned on, the luminance of the fourth area is 50% or less of the luminance of the third area.

[0010] (2) Furthermore, in one embodiment of the present invention, in addition to the configuration of (1) above, the backlight is a direct-type backlight in which a plurality of light-emitting elements are arranged in a matrix, and further includes a brightness adjustment mechanism for adjusting the brightness of the backlight, and the brightness adjustment mechanism adjusts the emission intensity of each of the plurality of light-emitting elements in accordance with the display image of the liquid crystal panel.

[0011] (3) Furthermore, in one embodiment of the present invention, in addition to the configuration of (1) above, the backlight is an edge-lit backlight having a light guide plate and a light-emitting element arranged on a side of the light guide plate, and the reflectance of a region of the light guide plate that overlaps with the fourth region is lower than the reflectance of a region of the light guide plate that overlaps with the third region.

[0012] (4) Another embodiment of the present invention is a display device comprising a liquid crystal panel, a front panel arranged on the observer side of the liquid crystal panel, and a backlight arranged on the rear side of the liquid crystal panel, wherein the liquid crystal panel has, in a planar view, a display area and a frame area arranged around the display area, the front panel includes a design layer that overlaps the display area in a planar view, transmits at least a portion of the light incident from the liquid crystal panel and reflects at least a portion of the light incident from the observer side, and wherein the difference in luminance between the display area of ​​the liquid crystal panel in a black display state and the luminance of the frame area is 5% or less under 500 to 1000 lux.

[0013] (5) In addition to the configuration of (4) above, one embodiment of the present invention further includes a brightness adjustment mechanism for adjusting the brightness of the backlight, and the brightness adjustment mechanism controls the backlight to be constantly lit in a reflective display in which the pattern of the design layer is visible to the observer by reflection of light incident from the observer side.

[0014] (6) Moreover, in one embodiment of the present invention, in addition to the configuration of (5) above, the liquid crystal panel is in a transmissive state during the reflective display.

[0015] (7) Moreover, an embodiment of the present invention is a display device having the configuration of any one of (1) to (6) above, wherein the transmittance of the area of ​​the front panel that overlaps with the display area is 50% or more.

[0016] (8) Moreover, one embodiment of the present invention is a display device having the configuration of any one of (1) to (7) above, wherein the front plate and the liquid crystal panel are bonded together with an optical contact layer.

[0017] (9) Moreover, in addition to the configuration of (8), an embodiment of the present invention is a display device, wherein the optical contact layer has a refractive index of 1.4 or more and 1.6 or less. Effect of the Invention

[0018] According to the present invention, it is possible to provide a display device with reduced interface reflection and high brightness. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a plan view illustrating an example of a display device according to a first embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view taken along line X1-X2 in FIG. [Diagram 3] FIG. 11 is a reference diagram of a liquid crystal panel for explaining black floating during transmissive display. [Figure 4] FIG. 4 is a reference diagram of a display device in which a front panel is superimposed on the liquid crystal panel of FIG. [Diagram 5] FIG. 2 is a schematic plan view of a direct type backlight used in the first embodiment. [Figure 6] FIG. 2 is a plan view showing an edge-light type backlight used in the first embodiment. [Figure 7] 4 is a graph illustrating the luminance of a third region (iii) and a fourth region (iv) in the first embodiment. [Figure 8] FIG. 11 is a schematic cross-sectional view of a display device illustrating an example in which the front panel has a planarizing layer. [Figure 9] 1 is a schematic plan view of a display device in which the boundary between the display region and frame region of a liquid crystal panel and the outer edge of a black frame layer are overlapped. [Figure 10] FIG. 2 is a plan view showing an example of a black frame layer included in the front panel. [Figure 11] 11 is a schematic plan view of a first example in which a part of the second region shown in FIG. 10 is enlarged. FIG. [Figure 12] 11 is a schematic plan view of a second example in which a part of the second region shown in FIG. 10 is enlarged. FIG. [Figure 13] 11 is a schematic plan view of a third example in which a part of the second region shown in FIG. 10 is enlarged. FIG. [Figure 14] 11 is a schematic cross-sectional view of a display device illustrating an example in which a black layer is provided on the side surface of a liquid crystal panel and / or the inner wall of a housing. [Figure 15] FIG. 2 is a schematic cross-sectional view illustrating a part of the configuration of the display device according to the first embodiment and a display method. [Figure 16] FIG. 11 is a cross-sectional view showing an example of a display device according to embodiment 3. [Figure 17] FIG. 2 is a schematic cross-sectional view illustrating a part of the configuration of a display device according to a first embodiment and a display method. [Figure 18] FIG. 11 is a schematic cross-sectional view illustrating a part of the configuration of a display device according to a second embodiment and a display method. [Figure 19] 1 is a graph showing the interface reflectance when light is incident from a medium having a refractive index of 1.5 to a medium having a refractive index of 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will be described in more detail with reference to the drawings, with the following embodiments, but the present invention is not limited to these embodiments. In the following description, the same reference numerals are used in different drawings for the same parts or parts having similar functions, and repeated description thereof will be omitted. Each aspect of the present invention may be combined as appropriate within the scope of the present invention.

[0021] In this specification, when two directions are perpendicular to each other, the angle between the two directions is preferably within a range of 90°±3°, more preferably within a range of 90°±1°, and even more preferably within a range of 90°±0.5°. When two directions are parallel to each other, the angle between the two directions is preferably within a range of 0°±3°, more preferably within a range of 0°±1°, and even more preferably within a range of 0°±0.5°.

[0022] In this specification, the term "observer side" refers to the surface from which an observer views the display device, and is also referred to as the "front side." The term "rear side" refers to the surface opposite the observer side.

[0023] <Embodiment 1> The display device according to the first embodiment includes a liquid crystal panel, a front plate disposed on the viewer side of the liquid crystal panel, and a backlight disposed on the rear side of the liquid crystal panel, the liquid crystal panel having a display area and a frame area disposed around the display area in a plan view, the front plate including a design layer overlapping the display area in a plan view, transmitting at least a part of the light incident from the liquid crystal panel and reflecting at least a part of the light incident from the viewer side, the backlight including a third area overlapping the display area of ​​the liquid crystal panel in a plan view, and a fourth area overlapping the display area of ​​the liquid crystal panel and disposed around the third area in a plan view, and when the backlight is turned on, the luminance of the fourth area is 50% or less of the luminance of the third area. In the first embodiment, the configuration of the backlight makes it difficult to visually recognize the boundary between the display area and the frame area during transmissive display.

[0024] Fig. 1 is a plan view schematic diagram showing an example of a display device according to embodiment 1. Fig. 2 is a cross-sectional view schematic diagram taken along line X1-X2 in Fig. 1. As shown in Fig. 2, a display device 1-A according to embodiment 1 includes a liquid crystal panel 100, a front plate 110 arranged on the viewer's side of the liquid crystal panel 100, and a backlight 200 arranged on the rear side of the liquid crystal panel 100. The configurations of the liquid crystal panel 100 and the front plate 110 will be described later.

[0025] As shown in Fig. 1, the liquid crystal panel 100 has, in a plan view, a display area and a frame area arranged around the display area. In Fig. 1, the dotted line indicates the boundary between the display area and the frame area of ​​the liquid crystal panel, and the inner outer edge of the black matrix 23 shown in Fig. 2 on the liquid crystal panel forms the boundary between the display area and the frame area. The display area is an area including a plurality of pixels, and is an area where a desired image or the like is displayed during transmissive display. The frame area is an area that overlaps with a housing or a bezel, and is not involved in transmissive display.

[0026] The black floating phenomenon will be explained below with reference to Fig. 3 and Fig. 4. Fig. 3 is a reference diagram of a liquid crystal panel for explaining the black floating phenomenon during transmissive display. Fig. 4 is a reference diagram of a display device in which a front panel is superimposed on the liquid crystal panel of Fig. 3.

[0027] Even when black is displayed in the display area of ​​a liquid crystal panel, black floating may be observed. As shown in Figure 3, an example is shown in which the alphabet A is displayed in white in the display area of ​​a liquid crystal panel, with the background of the characters displayed in black. Because a small amount of backlight light passes through the liquid crystal panel even in the black display state, the black in the display area may appear slightly brighter than pure black (black floating). The above-mentioned black floating is expressed as the product of the transmittance of the liquid crystal panel in the black display state and the luminance of the backlight. To explain in concrete numerical terms, the transmittance of a liquid crystal panel in the black display state is usually around 0.006%, and if the luminance of the backlight is assumed to be 10,000 cd / m 2 So the black floating is 0.6cd / m 2 This difference is only about the same as the black of the frame area, and is clearly visible. Even if a front panel is placed on an LCD panel with such a black floating area, as shown in Figure 4, the boundary between the display area and the frame area will be visible during transmissive display.

[0028] In the first embodiment, when the backlight is turned on, the luminance of the fourth region (iv) overlapping with the frame region of the liquid crystal panel is 50% or less of the luminance of the third region (iii) overlapping with the display region of the liquid crystal panel. With this configuration, the boundary between the display region and the frame region can be made difficult to see during transmissive display of the liquid crystal panel.

[0029] (Backlight) The backlight may be a direct type backlight or an edge light type backlight. FIG. 5 is a plan view schematic diagram of a direct type backlight used in the first embodiment. FIG. 6 is a plan view schematic diagram of an edge light type backlight used in the first embodiment. In FIGS. 5 and 6, the positions of the display area and frame area of ​​the liquid crystal panel are indicated by two-dot chain lines for reference. As shown in FIGS. 5 and 6, the backlights 200A and 200B each include a third area (iii) and a fourth area (iv) that overlap with the display area of ​​the liquid crystal panel in a plan view. Furthermore, the fourth area (iv) is disposed around the third area (iii).

[0030] 5, the backlight may be a direct type backlight 200A in which a plurality of light emitting elements 201 are arranged in a matrix. The plurality of light emitting elements 201 may be arranged in the in-plane direction of a substrate 202. Although not shown, the backlight 200A may further include a diffusion film or the like. The substrate 202 is not particularly limited, and a substrate known in the field of backlights may be used.

[0031] As the light emitting element 201, any element known in the field of backlights can be used, such as a light emitting diode (LED).

[0032] The backlight 200A further includes a brightness adjustment mechanism for adjusting the brightness of the backlight, and the brightness adjustment mechanism preferably adjusts the emission intensity of each of the plurality of light-emitting elements 201 according to the display image of the liquid crystal panel 100. A driving method for adjusting the emission intensity of each of the plurality of light-emitting elements 201 according to the display image of the liquid crystal panel 100 is also called partial driving (local dimming).

[0033] The brightness adjustment mechanism preferably adjusts the brightness of the plurality of light-emitting elements 201 arranged in the third region (iii) and the brightness of the plurality of light-emitting elements 201 arranged in the fourth region (iv) shown in Fig. 5 so that the brightness of the fourth region of the backlight 200A is 50% or less of the brightness of the third region. When the display image of the liquid crystal panel 100 displays black, the light-emitting elements 201 overlapping the region displaying black can be turned off to suppress black floating.

[0034] 6, the backlight may be an edge-light type backlight 200B including a light guide plate 203 and light emitting elements 201 arranged on the side surface of the light guide plate 203. Although not shown, the backlight 200B may further include a reflective sheet, a diffusion film, and the like.

[0035] There is no particular limitation on the light guide plate 203, and any plate known in the field of backlights can be used. The surface of the light guide plate 203 may be provided with irregularities, grooves, textured finish, or the like, in order to emit light incident from the light emitting elements 201 arranged on the side surface to the viewer side.

[0036] 6, the reflectance of the region overlapping with the fourth region (iv) of the light guide plate 203 is preferably lower than the reflectance of the region overlapping with the third region (iii). By making the reflectance of the region overlapping with the fourth region (iv) lower than the reflectance of the region overlapping with the third region (iii), it is preferable to adjust the luminance of the fourth region of the backlight 200B to be 50% or less of the luminance of the third region.

[0037] The reflectance of the light guide plate 203 can be adjusted, for example, by changing the density of the structures such as the unevenness, grooves, grain, etc. By making the density of the structures formed in the region overlapping with the fourth region (iv) lower than the density of the structures formed in the region overlapping with the third region (iii), the reflectance of the region overlapping with the fourth region (iv) can be made lower than the reflectance of the region overlapping with the third region (iii).

[0038] Fig. 7 is a graph illustrating the luminance of the third region (iii) and the fourth region (iv) in the first embodiment. As shown in Fig. 7, the luminance may be highest in the center of the third region (iii) and may decrease toward the outer edge of the fourth region (iv) (the boundary between the fourth region (iv) and the frame region). There may not be a clear luminance boundary between the third region (iii) and the fourth region (iv), and it is preferable that the luminance changes gradually. If the maximum luminance of the third region (iii) is 100%, the luminance of the boundary between the third region (iii) and the fourth region (iv) is preferably 50% or less.

[0039] (Liquid crystal panel) 2, the liquid crystal panel 100 may include a pair of substrates and a liquid crystal layer sandwiched between the pair of substrates. The pair of substrates may be a TFT substrate 10 having switching elements such as thin film transistors (TFTs), and a color filter (CF) substrate 20 having color filters. The TFT substrate 10 and the CF substrate 20 are bonded together with a sealant 40, and a liquid crystal layer 30 is enclosed between the two substrates.

[0040] Although not shown, the TFT substrate 10 may have a structure in which a gate line and a source line intersecting the gate line are disposed on a support substrate, a TFT is disposed near the intersection of the gate line and the source line, and a pixel electrode electrically connected to the TFT is disposed. The area surrounded by the gate line and the source line is a pixel.

[0041] The pixel electrode and the counter electrode described later may be transparent electrodes, and may be formed of a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), tin oxide (SnO), or an alloy thereof.

[0042] The color filter substrate 20 may have, for example, a color filter layer 22 and a black matrix 23 arranged on a support substrate 21. The color filter layer 22 may include red, green, and blue color filters. Each color filter is arranged so as to overlap with a pixel of the TFT substrate, and a desired color can be expressed by mixing the colors while controlling the amount of light transmitted through each color filter.

[0043] The black matrix 23 may be disposed so as to separate the color filters in a plan view. The color filters and the black matrix are not particularly limited, and any known ones in the field of liquid crystal panels may be used.

[0044] The supporting substrate used for the TFT substrate 10 and the CF substrate 20 is preferably a transparent substrate, and examples thereof include a glass substrate and a plastic substrate.

[0045] The display mode of the liquid crystal panel may be either a vertical electric field mode or a horizontal electric field mode. The vertical electric field mode includes a vertical alignment (VA) mode in which liquid crystal molecules in the liquid crystal layer are aligned substantially perpendicular to the substrate surface when no voltage is applied. The horizontal electric field mode includes a fringe field switching (FFS) mode and an in-plane switching (IPS) mode in which liquid crystal molecules in the liquid crystal layer are aligned substantially horizontal to the substrate surface when no voltage is applied. The non-voltage application mode also includes a case in which a voltage less than the threshold value of the liquid crystal molecules is applied to the liquid crystal layer.

[0046] "Approximately horizontal" means that the tilt angle is 0° or more and 10° or less, preferably 0° or more and 5° or less, and more preferably 0° or more and 2° or less. "Approximately vertical" means that the tilt angle is 83° or more and 90° or less, preferably 85° or more and 90° or less, and more preferably 87.5° or more and 88.0° or less.

[0047] The liquid crystal layer 30 controls the amount of light transmission by changing the orientation of the liquid crystal molecules in response to an electric field generated in the liquid crystal layer 30 by a voltage applied between the pixel electrode and the counter electrode. In the vertical electric field method, the counter electrode is disposed on the TFT substrate side, and in the horizontal electric field method, the counter electrode is disposed on the CF substrate side.

[0048] The liquid crystal molecules may have a positive or negative dielectric anisotropy (Δε) defined by the following formula (L): Δε = (dielectric constant in the long axis direction) - (dielectric constant in the short axis direction) (L)

[0049] As shown in FIG. 2, the liquid crystal panel 100 may have a first linear polarizer 51 on the front side and a second linear polarizer 52 on the rear side. The first and second linear polarizers 51 and 52 are polarizers that transmit only light of a specific polarization direction. The linear polarizer may be an absorption-type linear polarizer having a transmission axis that transmits only light of a specific polarization direction and an absorption axis perpendicular to the transmission axis. The first and second linear polarizers 51 and 52 are preferably arranged so that their transmission axes are perpendicular to each other. The first and second linear polarizers 51 and 52 may be known polarizers, such as Nitto Denko's "TEG1465DU".

[0050] Although not shown, the first linear polarizer 51 may be attached to the surface of the CF substrate 20 opposite the liquid crystal layer 30 by a transparent adhesive, and the second linear polarizer 52 may be attached to the surface of the TFT substrate 10 opposite the liquid crystal layer 30 by a transparent adhesive.

[0051] Although not shown, an alignment film for controlling the alignment direction of liquid crystal molecules when no voltage is applied may be disposed between the TFT substrate 10 and the liquid crystal layer 30, and between the CF substrate 20 and the liquid crystal layer 30. As the alignment film, a material commonly used in the field of liquid crystal panels, such as a polymer having polyimide, polyamic acid, polysiloxane, or the like in its main chain, may be used.

[0052] (Front plate) Front plate 110 is a member that transmits at least a portion of the light incident from liquid crystal panel 100 and reflects at least a portion of the light incident from the viewer side.

[0053] The transmittance of the area of ​​the front plate 110 that overlaps with the display area of ​​the liquid crystal panel 100 is preferably 50% or more. The display device according to the first embodiment can perform transmissive display while maintaining high brightness of the display device because the transmittance of the front plate 110 is 50% or more. If the transmittance of the front plate 110 is less than 50%, the brightness of the display device is significantly reduced, making it difficult to see the displayed image in a bright environment. In order to make the displayed image more visible, it is necessary to increase the brightness of the backlight in order to increase the brightness of the display device, which increases the power consumption of the backlight. The transmittance of the front plate 110 is more preferably 70% or more. The upper limit of the transmittance of the front plate 110 is, for example, 90%. In this specification, the transmittance refers to total light transmittance, and is measured by a method conforming to JIS K 7361-1. The total light transmittance can be measured using, for example, a turbidity meter "HazeMeter NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd.

[0054] Conventionally, for example, the printed matter described in Patent Document 1 has a smoke layer, such as a transparent smoke print layer, arranged on the back side in order to suppress interface reflection. The smoke layer is a layer with low transmittance formed by solid printing or the like on the surface of a transparent substrate, and one having a transmittance of 70% or less is used as an example. When a smoke layer is arranged on the back side of the front plate, the transmittance of the front plate is considered to be less than 50%. It is preferable that a smoke layer is not arranged in the area of ​​the front plate 110 that overlaps with the display area of ​​the liquid crystal panel 100, and when the smoke layer is not arranged, it can be said that the transmittance of the area of ​​the front plate 110 that overlaps with the display area of ​​the liquid crystal panel 100 is 50% or more.

[0055] In the display region of the liquid crystal panel, the transmittance from the viewer-side surface of the liquid crystal panel 100 (the viewer-side surface of the first linear polarizer 51 in FIG. 1) to the viewer-side surface of the front panel (the surface of the transparent substrate 112 in FIG. 1) is preferably 50% or more, and more preferably 70% or more.

[0056] The front panel 110 includes a design layer 111 that overlaps with the display area of ​​the liquid crystal panel 100 in a plan view. The design layer 111 is a layer that expresses a specific pattern, etc., and in the reflective display state, the pattern, etc. is visually recognized by an observer. The specific pattern is not particularly limited, but examples thereof include a designed geometric pattern, a wood grain pattern, a specific character string, a company logo, etc.

[0057] The design layer 111 preferably contains a reflective pigment. The reflective pigment is a pigment that reflects light of a specific wavelength of external light toward the observer, and allows the observer to visually recognize a specific color depending on the reflected wavelength. The specific wavelength is light in the visible light range (380 nm to 780 nm). The design layer 111 may contain reflective pigments of multiple colors, and the reflected light of the reflective pigments of multiple colors is additively mixed to allow the observer to visually recognize a desired color.

[0058] Since the design layer 111 contains a reflective pigment, the front panel 110 can reflect at least a portion of the light incident from the viewer side. Since the design layer 111 has gaps between the pigments, the front panel 110 can transmit at least a portion of the light incident from the liquid crystal panel 100 to the viewer side.

[0059] Examples of the reflective pigment include interference pigments and metallic pigments.

[0060] The interference pigment is also called a pearl pigment, and may reflect light of a specific wavelength and transmit light of wavelengths other than the specific wavelength. The interference pigment may have a substrate and a coating layer that covers the substrate.

[0061] The substrate may be a flake transparent to light with wavelengths in the visible light region, and the coating layer may be a metal oxide film with a higher refractive index than the flakes. The interference pigment may be dispersed in a binder resin and applied to a base film. The color of the interference light visually recognized by an observer can be adjusted by changing the thickness of the coating layer. The interference pigment may be, for example, one listed in Patent Document 1 (Patent Publication No. 5725581).

[0062] When an interference pigment is used in the design layer 111, part of the external light is reflected at the interface between the air layer and the coating layer and the interface between the coating layer and the substrate. Another part of the external light passes through the substrate and is reflected at the surface of the base film. To the observer, these reflected lights are combined and visually recognized as a pearl-like interference light of a specific color that includes the color of the base film.

[0063] The metallic pigment may reflect light of a specific wavelength and absorb light of wavelengths other than the specific wavelength. Examples of the metallic pigment include metal pieces coated with a pigment, and the pigment may be further coated with a polymer such as an acrylic resin. Examples of the metallic pigment include "Friend Color (registered trademark)" manufactured by Toyo Aluminum K.K.

[0064] The metal pieces are preferably ones that reflect visible light, and examples thereof include aluminum, nickel, titanium, stainless steel, and alloys thereof.

[0065] The pigment that covers the metal pieces may be either an organic pigment or an inorganic pigment, but is preferably an organic pigment. Examples of the organic pigment include phthalocyanine, halogenated phthalocyanine, quinacridone, diketopyrrolopyrrole, isoindolinone, azomethine metal complex, indanthrone, perylene, perinone, anthraquinone, dioxazine, benzimidazolone, condensed azo, triphenylmethane, quinophthalone, and anthrapyrimidine. Examples of the inorganic pigment include titanium oxide, iron oxide, carbon black, and bismuth vanadate.

[0066] The design layer 111 may be a thin metal film, a film containing a light-reflecting pigment, a printed layer printed with a light-reflecting pigment, or the like.

[0067] The metal thin film may be formed by metal deposition, sputtering, etc., using metals such as aluminum, silver, titanium, tungsten, etc. The thickness of the metal thin film is, for example, 30 nm to 100 nm.

[0068] As another embodiment of the design layer 111, for example, as described in the above-mentioned Patent Documents 2 and 3, a specific pattern may be formed on a screen having a plurality of fine holes or on a decorative film having a plurality of transmitting portions.

[0069] 2, the design layer 111 may be disposed on the back side of the transparent substrate 112, or, although not shown, may be disposed on the front side of the transparent substrate 112. The design layer 111 may be disposed partially on the surface of the transparent substrate 112 so as to express a specific pattern or the like, and does not have to be disposed on the entire surface of the transparent substrate 112.

[0070] The transparent substrate 112 is preferably made of a light-transmitting material, and may be used as a printing substrate for the design layer 111. From the viewpoint of maintaining high brightness of the display device, the transparent substrate 112 preferably has a high transmittance, for example, a transmittance of 90% or more. From the viewpoint of suppressing blurring of the displayed image, the transparent substrate 112 preferably has a haze of 10% or less. The haze is measured by a method conforming to JIS K 7136. The haze can be measured, for example, using a turbidity meter "HazeMeter NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd.

[0071] For example, a glass plate, or a resin plate such as an acrylic or polycarbonate plate can be used as the transparent base material 112. The transparent base material 112 may have a flat surface or a curved surface.

[0072] The design layer 111 may be printed on the surface of the transparent substrate 112 by a printing method such as gravure printing, screen printing, or inkjet printing.

[0073] As shown in Fig. 2, when the design layer 111 is disposed on the rear side of the transparent substrate 112, the design layer 111 can be prevented from being scratched. Placing the transparent substrate 112 on the viewer side creates a sense of depth and gloss, but depending on the pattern of the design layer 111, the texture may be perceived as inferior due to the sense of depth and gloss. From the viewpoint of expressing the texture of the design layer 111 more vividly, it is preferable that the design layer 111 be disposed on the front side of the transparent substrate 112. On the other hand, when the design layer 111 is disposed on the front side of the transparent substrate 112, the design layer 111 is easily scratched, so a hard coat layer (not shown) may be further provided on the front side of the design layer 111.

[0074] The hard coat layer is preferably one having high transparency and scratch resistance, and examples thereof include a coating layer of an acrylic resin, an epoxy resin, etc. The hard coat layer preferably has a transmittance of 90% or more.

[0075] FIG. 8 is a schematic cross-sectional view of a display device illustrating a case where the front panel has a planarizing layer. As shown in FIG. 8, the front panel 110 may have a planarizing layer 114 on the rear side (liquid crystal panel 100 side) of the design layer 111. When the design layer 111 is a printed layer such as a screen printing layer, unevenness of about 5 to 10 μm may exist depending on the pattern of the design layer 111. If the printed layer has unevenness, fine air bubbles may be trapped between the front panel 110 and the optical contact layer 120, which may make the reflective display difficult to see. By disposing the planarizing layer 114 and making the surface of the front panel 110 facing the optical contact layer 120 flat (for example, 3 μm or less), the unevenness can be made difficult to trap air bubbles, and the reflective display can be made to look more vivid.

[0076] The planarization layer 114 is preferably a transparent resin layer, and may be made of, for example, a transparent resin such as an acrylic resin or an epoxy resin. The planarization layer 114 may be formed by printing the transparent resin. The planarization layer 114 preferably has a transmittance of 90% or more.

[0077] As shown in FIG. 2, the front panel 110 may have a black frame layer 113 on the rear side of the design layer 111. The black frame layer 113 is a light-shielding layer, and is preferably disposed in an area overlapping the area of ​​the liquid crystal panel 100 in a plan view. The transparent base material 112 is preferably larger than the display area of ​​the liquid crystal panel 100, and the black frame layer 113 may be disposed in an area (frame area) where the transparent base material 112 protrudes from the display area. By disposing the black frame layer 113, stray light from the liquid crystal panel 100 side can be blocked, and the design layer 111 can be made to look vivid. In addition, by disposing the black frame layer 113, it is possible to prevent a bezel, a frame, etc. from being seen through by an observer. The outer edge of the black matrix 23 of the liquid crystal panel 100 and the outer edge of the black frame layer 113 may or may not match.

[0078] The material of the black frame layer 113 may be the same as that of the black matrix 23, or may be formed by a printing method such as screen printing using black pigments. The black frame layer 113 may be solid printed so that the transmittance is almost uniform, or may be gradation printed as described later. A black tape may also be used.

[0079] Fig. 9 is a schematic plan view of a display device in which the boundary between the display area and frame area of ​​the liquid crystal panel and the outer edge of the black frame layer are overlapped. Fig. 10 is a schematic plan view showing an example of a black frame layer included in a front panel. In Figs. 9 and 10, the dotted line indicates the boundary between the display area and frame area of ​​the liquid crystal panel, and the dashed and dotted line corresponds to the outer edge of the black frame layer 113 on the inner side of the liquid crystal panel shown in Fig. 2.

[0080] Even when the liquid crystal panel is turned off, the display area may appear slightly brighter than the frame area when the display device is observed from an oblique direction. By adjusting the reflectance of the area of ​​the front panel that overlaps with the frame area of ​​the liquid crystal panel, the boundary between the display area and the frame area can be made less noticeable even when the display device is observed from an oblique direction.

[0081] 10, front panel 110 may include a first region (i) overlapping the display region of the liquid crystal panel in a plan view, and a second region (ii) arranged around the first region (i). Note that second region (ii) of front panel 110 may partially overlap the frame region of the liquid crystal panel in a plan view, or may not coincide with the frame region.

[0082] The reflectance of the second region (ii) is preferably 6% or more and 12% or less. The first region (i) of the front plate 110 overlaps with the display region of the liquid crystal panel in a plan view, and the design layer 111 is arranged therein. When the design layer 111 contains a reflective pigment, the reflectance of the first region (i) of the front plate 110 may be approximately 10% or more. As shown in FIG. 2, a black frame layer 113 may be arranged in the region overlapping with the frame region of the liquid crystal panel, but the black frame layer 113 is usually a light-shielding member and has a reflectance of approximately 0%. By arranging the second region (ii) having a reflectance of 6% or more and 12% or less around the first region (i) of the front plate 110, the boundary between the display region and the frame region can be made less noticeable even when the display device is observed from an oblique direction.

[0083] It is preferable that the reflectance of the first region (i) and the reflectance of the second region (ii) are approximately the same. For example, the difference between the reflectance of the first region (i) and the reflectance of the second region (ii) is preferably 15% or less, more preferably 5% or less, and even more preferably 3% or less.

[0084] The second region (ii) preferably has a reflectance that increases from the inner periphery of the liquid crystal panel toward the first region (i). Specifically, in plan view, the black frame layer 113 is preferably disposed on the rear side of the design layer 111 of the front panel 101 and in an area that overlaps with the frame area of ​​the liquid crystal panel, and the second region (ii) may be gradation-printed so that the reflectance of the black frame layer 113 increases toward the first region (i).

[0085] 11 to 13 are schematic plan views of first to third examples, which are enlarged views of a portion of the second region shown in Fig. 10. Figs. 11 to 13 correspond to the portion surrounded by the two-dot chain line in Figs. 9 and 10. As long as the reflectance of the black frame layer 113 can be increased toward the first region (i), the method of gradation printing of the black frame layer 113 is not particularly limited. For example, as shown in Fig. 11, the shade of the black frame layer 113 may be changed continuously, as shown in Fig. 12, the shade of the black frame layer 113 may be changed stepwise, or as shown in Fig. 13, the area of ​​the dots may be reduced toward the first region (i) to change the shade of the black frame layer 113.

[0086] (Optical contact layer) The optical contact layer 120 is a transparent adhesive layer or bonding layer used for bonding optical members, and may be a sheet-like adhesive layer or a cured liquid adhesive.

[0087] The front plate 110 and the liquid crystal panel 100 are preferably bonded together by the optical contact layer 120. It can also be said that the front plate 110 and the liquid crystal panel 100 are integrated together by the optical contact layer 120. The front plate 110 and the liquid crystal panel 100 are bonded together by the optical contact layer 120 as long as there is no air layer between the front plate 110 including the design layer 111 and the liquid crystal panel 100. The front plate 110 and the liquid crystal panel 100 may each be in contact with the optical contact layer 120, or a member other than the optical contact layer 120, such as a transparent substrate, may be present between the front plate 110 and the liquid crystal panel 100.

[0088] Since there is no air layer between the front plate 110 and the liquid crystal panel 100, reflection at the air interface is eliminated, and the internal reflectance of the entire display device can be reduced. By reducing the internal reflectance of the entire display device, the color of the pattern of the design layer 111 does not become whitish in the reflective display, and a clear and vivid color can be visually recognized. The display device 1-A according to the first embodiment can achieve a vivid reflective display without disposing a semi-transparent smoke layer such as the transparent smoke print layer of Patent Document 1. Furthermore, since the display device according to the embodiment does not have a smoke layer, it is possible to achieve both a vivid reflective display and a highly luminous transmissive display without reducing the luminance during the transmissive display.

[0089] The rear surface of the front plate 110 and the front surface of the liquid crystal panel 100 are preferably in contact with an optical contact layer 120. The optical contact layer 120 may be a single layer or a laminate of multiple optical contact layers, but is preferably a single layer.

[0090] The optical contact layer 120 preferably has a refractive index of 1.4 or more and 1.6 or less. The refractive index of the optical contact layer 120 is at least greater than 1 (refractive index of air at 0° C. and 1 atmospheric pressure), and is preferably greater than the refractive index of the transparent substrate 112 or the polarizing plate on the front side of the liquid crystal panel (first linear polarizing plate 51 in FIG. 2). By making the refractive index of the optical contact layer 120 1.4 or more and 1.6 or less, it is possible to suppress the transmitted light that has passed through the design layer 111 from being reflected at an interface and returning to the viewer side. The interface reflected light of the transmitted light that has passed through the design layer 111 has a complementary color relationship with the light reflected by the design layer 111, so by suppressing the interface reflected light, a more vivid reflective display can be obtained.

[0091] The optical contact layer 120 preferably has a transmittance of 90% or more and a haze of 10% or less. Examples of the optical contact layer 120 include the "LUCIACS CS986" series manufactured by Nitto Denko Corporation.

[0092] By making the thickness of the optical contact layer 120 sufficiently thicker than the thicknesses of the design layer 111, the black frame layer 113, etc., it is possible to prevent air bubbles from being trapped when the liquid crystal panel 100 and the front panel 110 are bonded together. The thickness of the optical contact layer 120 is preferably 10 times or more the thickness of the black frame layer 113. For example, when the thickness of the black frame layer 113 is 20 μm, the thickness of the optical contact layer 120 is preferably 200 μm or more.

[0093] Furthermore, the thickness of the optical contact layer 120 is preferably 200 μm or more even when the design layer 111 is disposed on the back side of the front panel 110. By making the thickness of the optical contact layer 120 200 μm or more, even when the design layer 111 has irregularities of 5 to 10 μm, the design layer 111 and the liquid crystal panel can be bonded together without any air bubbles being trapped between them.

[0094] (Housing) The display device according to the first embodiment may further include a housing 300 that houses the liquid crystal panel 100 and the front plate 110. A double-sided tape 301 may be arranged on the rear side of the front plate 110 that overlaps the frame region (on the rear side of the black frame layer 113 in FIG. 2) and fixed to the housing 300. A circuit board (not shown) on which a drive circuit for driving the liquid crystal panel 100 and the backlight 200 is formed may be stored inside the housing 300. The housing 300 is not particularly limited as long as it can house the liquid crystal panel 100 and the front plate 110, and may be made of metal or resin. The shape of the housing 300 is not limited to the shape shown in FIG. 2.

[0095] Fig. 14 is a schematic cross-sectional view of a display device illustrating a case where a black layer is provided on the side surface of the liquid crystal panel and / or the inner wall of the housing. As shown in Fig. 14, a black layer 302, which is a light-shielding member, may be provided on the side surface of the liquid crystal panel 100 and / or the inner surface (inner wall) of the housing 300. When the display device 1-A is viewed from an oblique direction, the display area may appear slightly bright due to stray light from the backlight 200, but by providing the black layer 302, the stray light can be absorbed.

[0096] The black layer 302 may be formed by coating a black pigment, or by attaching a cushioning material such as a black light-shielding tape or a black sponge. From the viewpoint of obtaining an effect of protecting the display device from impact, it is preferable to place the cushioning material.

[0097] <Explanation of display method> A display method of the display device according to the first embodiment will be described below with reference to FIG. 15. FIG. 15 is a schematic cross-sectional view illustrating a part of the configuration of the display device according to the first embodiment and the display method. In FIG. 15, a double-headed arrow in one direction and a double-headed arrow crossing at right angles represent the polarization state of light, and the double-headed arrow in one direction represents linearly polarized light whose vibration direction is one direction. The double-headed arrow crossing at right angles represents non-polarized light. In the following, a case where each member is bonded together with an adhesive layer 130 will be illustrated, but the adhesive layer 130 may be omitted if the members are in close contact with each other without an air layer between them.

[0098] The display device according to the embodiment can perform reflective display and transmissive display. In this specification, reflective display refers to a display method in which the pattern of the design layer is visually recognized by the observer by reflecting light (external light) incident on the display device from the observer side. In this specification, transmissive display refers to a display method in which light (display light) emitted from the liquid crystal panel side is transmitted through the front plate and emitted to the observer side, allowing the observer to visually recognize any image or the like displayed on the liquid crystal panel.

[0099] The transmissive display can be achieved by turning on the backlight when the liquid crystal panel is in a white display state. The reflective display can be achieved when the liquid crystal panel is in a black display state and the backlight is on or off. The reflective display can also be achieved when the liquid crystal panel is in a white display state, for example, by turning off the backlight or reducing the backlight light to a level where the pattern of the design layer can be visually recognized by an observer through reflected light.

[0100] The black display state refers to a state in which the orientation direction of the liquid crystal molecules is substantially parallel to the transmission axis of the first linear polarizer 51 or the second linear polarizer 52. The white display state refers to a state in which the orientation direction of the liquid crystal molecules forms an angle with the transmission axis of the first linear polarizer 51 or the second linear polarizer 52, and light can be transmitted to the observer side when light is emitted from a backlight. When the orientation direction of the liquid crystal molecules forms an angle of 45° with the transmission axis of the first linear polarizer 51 or the second linear polarizer 52, the transmittance becomes maximum, and the liquid crystal panel can be in a state with the highest brightness (all white state).

[0101] As shown in FIG. 15, in the transmissive display, light (L1) emitted from the viewer side of the liquid crystal panel 100 passes through the first linear polarizer 51 arranged on the viewer side of the liquid crystal panel 100. L1 passes through the optical contact layer 120, the design layer 111, and the transparent substrate 112, and is emitted to the viewer side. If the brightness of the light after emitting from the first linear polarizer 51 is the liquid crystal panel brightness (L2) and the transmittance of the design layer 111 is α, the brightness of the light L3 emitted to the viewer side (the brightness of the display device during transmissive display) is expressed as L2×α. Note that, although external light reflection, which will be described later, occurs in the transmissive display, when the amount of light emitted from the liquid crystal panel 100 side is sufficiently greater than the amount of external light, the viewer cannot easily see the pattern of the design layer, and can see any image displayed on the liquid crystal panel 100.

[0102] Next, the reflective display will be described. As shown in FIG. 15, if the light incident on the display device from the viewer side is external light L4, a part of L4 passes through the transparent base material 112, is reflected by the design layer 111, and is emitted to the viewer side (L5). Another part of L4 passes through the design layer 111, the optical contact layer 120, and the first linear polarizer 51, and is incident on the liquid crystal panel 100. A part of the light incident on the liquid crystal panel 100 is absorbed by a color filter or the like inside the liquid crystal panel 100 (L6), and another part is internally reflected by members such as wiring and electrodes that constitute the liquid crystal panel 100, passes through the design layer 111 again, and is emitted to the viewer side (internal reflected light L7). Since the internal reflected light L7 passes through the design layer 111 twice, if the internal reflectance of the liquid crystal panel 100 is β, the internal reflectance of the display device is α2 ×β.

[0103] The transmittance α of the design layer 111 varies depending on the pattern formed on the design layer 111. If the pattern is, for example, wood grain, the transmittance α is about 60 to 80%. The internal reflectance β of the liquid crystal panel 100 is a value obtained by subtracting the surface reflectance of the outermost surface of the liquid crystal panel 100 from the reflectance of the display area of ​​the liquid crystal panel 100. Although it depends on the density of the color filter and the pixel design, the internal reflectance β is usually about 1 to 2%. The internal reflectance of the liquid crystal panel is the reflectance between the TFT substrate 10 and the CF substrate 20 shown in FIG. 2, and does not include the reflectance of the first linear polarizer 51 on the front side.

[0104] Since the display device according to the embodiment does not have a smoke layer, the brightness of the display device during transmissive display is reduced by the transmittance α of the design layer 111, and there is almost no reduction in brightness due to components other than the design layer 111. Therefore, there is no need to increase the brightness of the liquid crystal panel 100 by using a backlight, and power consumption and heat generation can be reduced. In addition, it is preferable that the liquid crystal panel 100 and the front plate 110 are bonded together and integrated with an optical contact layer 120. In this case, since no interfacial reflection occurs between the liquid crystal panel 100 and the front plate 110, the internal reflectance of the display device during reflective display is the product of the internal reflectance β of the liquid crystal panel 100 and the amount of light passing twice through the transmittance α of the design layer 111 and the internal reflectance β of the liquid crystal panel 100 (α 2 The above α and β can be measured using, for example, a spectrophotometer CM-5 manufactured by Konica Minolta.

[0105] As shown in Figure 2, for a display device in which a liquid crystal panel 100 and a front panel 110 are bonded together with an optical adhesion layer 120, the luminance of the display device during transmissive display and the internal reflectance of the display device during reflective display will be considered below with reference to a reference embodiment.

[0106] <Reference form 1> 17 is a schematic cross-sectional view illustrating a part of the configuration and a display method of the display device according to Reference Form 1. The display device 1001 of Reference Form 1 has the same configuration as that of FIG. 2, except that the liquid crystal panel 100 and the front plate 110 are not bonded together with the optical contact layer 120, and an air layer 400 is provided between the liquid crystal panel 100 and the front plate 110.

[0107] As shown in FIG. 17, the luminance of light L3 emitted to the viewer side during transmissive display is L2×α, as in the description using FIG.

[0108] Regarding the reflective display, the reflected light L5 of the external light L4 on the surface of the design layer 111 and the light L6 absorbed inside the liquid crystal panel are the same as those explained using FIG. 15, so the explanation will be omitted. Since the reference form 1 has an air layer 400 between the liquid crystal panel 100 and the front plate 110, a part of the external light L4 is reflected at the interface between the front plate 110 and the air layer 400 (L7-1). A part of the external light L4 incident on the liquid crystal panel is internally reflected by the members constituting the liquid crystal panel, and is combined with the above-mentioned interface reflected light L7-1 and emitted to the viewer side (L7). If the above-mentioned interface reflectance is y, the internal reflectance of the display device of the reference form 1 is approximately y×α 2 +α 2 ×β.

[0109] <Reference form 2> Fig. 18 is a schematic cross-sectional view illustrating a part of the configuration and the display method of the display device according to Reference Form 2. The display device 1002 of Reference Form 2 has the same configuration as that of Fig. 2, except that the liquid crystal panel 100 and the front plate 110 are not bonded together with the optical contact layer 120, and an air layer 400 is provided between the liquid crystal panel 100 and the front plate 110, and a smoke layer 401 is disposed on the rear side of the design layer 111.

[0110] The smoke layer 401 can be formed by applying a resin composition in which a transparent resin is mixed with a black pigment to the rear side of the front panel, etc. The transmittance γ of the smoke layer 401 can be adjusted by the amount of black pigment added, and is, for example, 70% or less.

[0111] As shown in FIG. 18, in reference form 2, a smoke layer 401 is arranged, and if the transmittance of the smoke layer 401 is γ%, the luminance of light L3 emitted to the viewer side during transmissive display is L2×α×γ.

[0112] Regarding the reflective display, the reflected light L5 of the external light L4 on the surface of the design layer 111 and the light L6 absorbed inside the liquid crystal panel are the same as those explained using FIG. 15, so the explanation will be omitted. Since the reference form 2 has an air layer 400 between the liquid crystal panel 100 and the front plate 110, part of the external light L4 is reflected at the interface between the smoke layer 401 and the air layer 400 (L7-2). Part of the external light L4 incident on the liquid crystal panel is internally reflected by the members constituting the liquid crystal panel, and is combined with the above-mentioned interface reflected light 7-2 and emitted to the viewer side (L7). If the above-mentioned interface reflectance is z, the internal reflectance of the display device of the reference form 2 is approximately z×α 2 ×γ 2 +α 2 ×β.

[0113] Assuming α = 70%, β = 1.5%, and γ = 70%, the luminance of light L3 emitted to the observer side during transmissive display for the configuration of Figure 2 and reference forms 1 and 2, and the internal reflectance of the display device during reflective display were calculated, and the results are summarized in Table 1 below.

[0114] [Table 1]

[0115] As shown in Table 1, the internal reflectance of the configuration shown in Figure 2 is low at 0.7%, so that in the reflective display, the design layer pattern can be made vivid without becoming whitish. In addition, since the luminance of L3 is high, in the transmissive display, the displayed image can be displayed without becoming dark.

[0116] On the other hand, Reference Form 1 has a high internal reflectance of 2.7%, which reflects more external light than the configuration shown in Fig. 2, making the design layer pattern look whitish. Reference Form 2 suppresses external light reflection more than Reference Form 1, but the luminance of L3 is 49%, making the displayed image dark in transmissive display.

[0117] FIG. 19 is a graph showing the interface reflectance when light is incident from a medium with a refractive index of 1.5 to a medium with a refractive index of 1. The interface reflectance is derived from the Fresnel reflection formula and is a function according to the refractive index of the medium and the incident angle. FIG. 19 illustrates a case where the normal direction of the medium such as a substrate is 0°, and the interface reflectance when the incident angle of light is 0° is 4%. Although there is a difference in the incident angle at which total reflection occurs between P-polarized light and S-polarized light, the interface reflectance increases as the incident angle increases. In other words, when the display device is observed from an oblique direction, the difference in interface reflectance between the configuration shown in FIG. 2 and reference forms 2 and 3 is larger than when observed from the normal direction.

[0118] <Embodiment 2> A display device according to a second embodiment includes a liquid crystal panel, a front panel disposed on the viewer side of the liquid crystal panel, and a backlight disposed on the rear side of the liquid crystal panel, the liquid crystal panel having a display area and a frame area disposed around the display area in a plan view, the front panel including a design layer overlapping the display area in a plan view, transmitting at least a portion of light incident from the liquid crystal panel and reflecting at least a portion of light incident from the viewer side, and a difference in luminance between the display area and the frame area of ​​the liquid crystal panel in a black display state under 500 to 1000 lux is 5% or less. In the second embodiment, the backlight can be controlled to make it difficult to visually recognize the boundary between the display area and the frame area during transmissive display.

[0119] In the second embodiment, the difference in luminance between the display area of ​​the liquid crystal panel in the black display state and the frame area in a bright room (500 to 1000 lux) is set to be approximately the same (5% or less), thereby making it difficult to see the boundary between the display area and the frame area of ​​the liquid crystal panel. As shown in Fig. 2, when a black frame layer 113 is disposed on the rear side of the design layer 111 of the front panel 110, the reflectance of the frame area overlapping with the black frame layer 113 is approximately 6 to 12%.

[0120] The configuration of the front panel 110 other than the black frame layer 113 can be the same as that of the first embodiment, and therefore a duplicated description will be omitted. In addition, the liquid crystal panel used can be the same as that used in the first embodiment, and therefore a duplicated description will be omitted.

[0121] The backlight used in the second embodiment is not particularly limited, and a known backlight can be used, for example, an edge light type in which a light source is arranged on an end face of a light guide plate, or a direct type in which a large number of light sources are arranged in a plane and uniformity is improved with a diffusion plate, etc. According to the second embodiment, even if a backlight having areas with different luminance as in the first embodiment is not used, the boundary between the display area and the frame area of ​​the liquid crystal panel can be made difficult to see.

[0122] As a specific configuration for making the difference in luminance between the display area and the frame area of ​​a liquid crystal panel in a black display state 5% or less, for example, the following configuration can be given.

[0123] In a first configuration of the second embodiment, the display device further includes a brightness adjustment mechanism for adjusting the brightness of the backlight, and the brightness adjustment mechanism controls the backlight to be always on in a reflective display in which the pattern of the design layer is visually recognized by the observer by reflection of light incident from the observer side. By keeping the backlight on even when the desired display image is not displayed on the liquid crystal panel (when the liquid crystal panel is not in use), the boundary between the display area and the frame area of ​​the liquid crystal panel can be made difficult to see.

[0124] In the above-mentioned configuration in which the backlight is always on for the reflective display, the liquid crystal panel may be in a black display state (hereinafter also referred to as driving method A). Also, in the above-mentioned configuration in which the backlight is always on for the reflective display, the liquid crystal panel may be in a transmissive state (hereinafter also referred to as driving method B). From the viewpoint of reducing power consumption, the above-mentioned driving method B (the liquid crystal panel is in a transmissive state in a configuration in which the backlight is always on) is preferable.

[0125] The above-mentioned transmissive state in driving method B is preferably a state in which the brightness of the liquid crystal panel is the highest (all-white state). Furthermore, in driving method B, it is preferable that the liquid crystal panel is in the all-white state and the backlight is dimly lit. Dimly lit backlight refers to, for example, a state in which the brightness of the backlight is, for example, 5 to 10 cd / m 2 It is.

[0126] Specifically, if the contrast of the liquid crystal panel is 1500 and the transmittance of the liquid crystal panel in the black display state is δ%, the transmittance of the liquid crystal panel in the white display state is 1500×δ%. For example, if the backlight is 10,000 cd / m 2 A driving method (driving method A) in which the backlight is turned on at 6.7 cd / m and the LCD panel in the black display state is displayed with a transmittance of δ%. 2 This method achieves the same brightness as the driving method (driving method B) in which the LCD panel is turned on at 400° C. and displays a white display state with a transmittance of 1500×δ%. In other words, by using driving method B, the same effect (brightness) can be achieved with approximately 1 / 1500 the power consumption of driving method A. Driving method B is particularly effective for smartphones and the like that are powered by batteries, etc.

[0127] If the above driving method A and driving method B are calculated using more specific transmittance, the calculation can be made as follows. Driving method A: Black state transmittance 0.0067% x backlight brightness 10000cd / m 2 =0.67cd / m 2 Driving method B: Full white transmittance 10% x backlight brightness 6.7cd / m 2 =0.67cd / m 2 That is, while driving method A and driving method B provide the same luminance of the display device, driving method B requires 1 / 1500 of the power consumption (standby power).

[0128] Also in the second embodiment, the transmittance of the area of ​​front plate 110 overlapping with the display area of ​​liquid crystal panel 100 is preferably 50% or more. In other words, it is preferable that no smoke layer is disposed in the area of ​​front plate 110 overlapping with the display area of ​​liquid crystal panel 100. When the transmittance of front plate 110 is 50% or more, transmissive display can be performed while maintaining high brightness of the display device. The transmittance of front plate 110 is more preferably 70% or more. The upper limit of the transmittance of front plate 110 is, for example, 90%.

[0129] It is preferable that the front plate 110 and the liquid crystal panel 100 are bonded together by an optical adhesion layer 120. Since there is no air layer between the front plate 110 and the liquid crystal panel 100, reflection at the air interface is eliminated, the internal reflectance of the entire display device can be reduced, and a vivid reflective display can be realized.

[0130] The optical contact layer 120 preferably has a refractive index of 1.4 or more and 1.6 or less. With the above-mentioned configuration, it is possible to suppress the light transmitted through the design layer 111 from being reflected at the interface and returning to the viewer, thereby obtaining a more vivid reflective display.

[0131] <Embodiment 3> Fig. 16 is a cross-sectional schematic diagram showing an example of a display device according to embodiment 3. As shown in Fig. 16, in display device 1-B according to embodiment 3, liquid crystal panel 100 has circular polarizer 53 on the front plate 110 side. By disposing circular polarizer 53 on the front plate 110 side (front side) of liquid crystal panel 100, it is possible to almost eliminate the reflectance of the surface of liquid crystal panel 100, and therefore it is possible to significantly reduce the internal reflectance. Since the display device 1-B according to embodiment 3 is similar to embodiment 1 except that it has circular polarizer 53 on the front plate 110 side, a duplicated description will be omitted.

[0132] The circular polarizer 53 is a polarizing element that converts incident light into circularly polarized light. The liquid crystal panel 100 may also have a circular polarizer 54 on the back side. Examples of the circular polarizers 53 and 54 include a laminate of a λ / 4 wavelength plate and a linear polarizer. It is preferable that the transmission axis of the linear polarizer included in the circular polarizer 53 and the transmission axis of the linear polarizer included in the circular polarizer 54 are arranged so as to be perpendicular to each other.

[0133] The λ / 4 wave plate is not particularly limited as long as it imparts a 1 / 4 phase difference to incident light of wavelength λ. The λ / 4 wave plate is a retardation plate that imparts an in-plane phase difference of 1 / 4 wavelength (137.5 nm to be exact) to light of wavelength 550 nm, for example, and is preferably one that imparts an in-plane phase difference of 120 nm or more and 150 nm or less.

[0134] The λ / 4 waveplate may have a fast axis and a slow axis perpendicular to the fast axis. The fast axis of the λ / 4 waveplate may be disposed to form an angle of substantially 45° with the transmission axis of the third linear polarizer. Substantially 45° is preferably within the range of 45°±3°, more preferably within the range of 45°±1°, and even more preferably within the range of 45°±0.5°.

[0135] When the liquid crystal panel 100 has a circular polarizer 53 on the front side, transmittance modulation can be suitably performed, so that the display mode of the liquid crystal panel 100 is preferably a vertical electric field type such as a VA mode rather than a horizontal electric field type such as an IPS mode.

[0136] The liquid crystal panel 100 may be configured to include, in this order, a first substrate having a first electrode, a liquid crystal layer, and a second substrate having a second electrode. The first substrate may be the TFT substrate 10 described in the first embodiment, and the first electrode may be a pixel electrode formed on the TFT substrate 10. The second substrate may be the CF substrate 20 described in the first embodiment, and the second electrode may be a counter electrode disposed to face the pixel electrode.

[0137] In a VA mode liquid crystal panel, the liquid crystal molecules contained in the liquid crystal layer 30 preferably have negative dielectric anisotropy and are preferably aligned approximately perpendicular to the TFT substrate 10 or CF substrate 20 when no voltage is applied to the liquid crystal layer 30.

[0138] When no voltage is applied, the liquid crystal molecules are aligned approximately vertically, so that light emitted from the backlight 200 (hereinafter, backlight light) is not transmitted to the viewer side, and the liquid crystal panel 100 is in a black display state. When a voltage equal to or higher than the threshold value of the liquid crystal molecules is applied between the pixel electrode and the counter electrode, the liquid crystal molecules are tilted from the approximately vertical direction, so that the backlight light is transmitted to the viewer side, and a white display state is achieved.

[0139] Also in the third embodiment, the transmittance of the area of ​​front plate 110 overlapping with the display area of ​​liquid crystal panel 100 is preferably 50% or more. Front plate 110 and liquid crystal panel 100 are preferably bonded together by optical contact layer 120. Moreover, the refractive index of optical contact layer 120 is preferably 1.4 or more and 1.6 or less.

[0140] As shown in Figure 16, for a display device in which a liquid crystal panel 100 and a front panel 110 are bonded together with an optical adhesion layer 120, the luminance of the display device during transmissive display and the internal reflectance of the display device during reflective display will be considered below with reference to a reference embodiment.

[0141] <Reference form 3> Reference form 3 differs from the configuration in Fig. 16 in that the liquid crystal panel and the front plate are not bonded together with an optical contact layer, and an air layer is provided between the liquid crystal panel and the front plate. The display method of the display device in reference form 3 will be described by replacing the first linear polarizer 51 of the liquid crystal panel in reference form 1 shown in Fig. 17 with a circular polarizer.

[0142] <Reference form 4> Reference form 4 differs from the configuration in Fig. 16 in that the liquid crystal panel and the front plate are not bonded together with an optical contact layer, but rather there is an air layer between the liquid crystal panel and the front plate, and in that a smoke layer is disposed on the rear side of the design layer. The display method of the display device in reference form 4 will be described by replacing the first linear polarizer 51 of the liquid crystal panel in reference form 2 shown in Fig. 18 with a circular polarizer.

[0143] The configuration in Fig. 16 and Reference Forms 3 and 4 use a circular polarizer, and therefore the internal reflectance β of the liquid crystal panel is lower, β = 0.5%, than the configuration in Fig. 2. The luminance of light L3 emitted to the viewer side during transmissive display and the internal reflectance of the display device during reflective display were calculated for the configuration in Fig. 16 and Reference Forms 3 and 4 assuming α = 70%, β = 0.5% and γ = 70%, and the results are summarized in Table 2 below.

[0144] [Table 2]

[0145] The internal reflectance of the display device in the configuration of FIG. 16 during reflective display is 0.2%, enabling a more vivid reflective display than the configuration of FIG.

[0146] The display devices according to the first to third embodiments may be used, for example, as an instrument panel for an automobile to display gauges such as a speedometer, or may be used as an operation panel for home appliances. [Explanation of symbols]

[0147] 1-A, 1-B, 1001, 1002: Display device 10: First substrate (TFT substrate) 20: Second board (CF board) 21: Support substrate 22: Color filter layer 23: Black Matrix 30: Liquid crystal layer 40: Sealing material 51: First linear polarizing plate 52: Second linear polarizer 53, 54: Circular polarizing plate 100: LCD panel 110: Front plate 111: Design layer 112: Transparent material 113: Black frame layer 114: Flattening layer 120: Optical contact layer 130: Adhesive layer 200: Backlight 200A: Direct backlight 200B: Edge-lit backlight 201: Light emitting element 202: Substrate 203: Light guide plate 300: Cabinet 301: Double-sided tape 302: Black layer 400: Air layer 401: Smoke layer

Claims

1. a liquid crystal panel, a front panel disposed on a viewer's side of the liquid crystal panel, and a backlight disposed on a rear side of the liquid crystal panel; the liquid crystal panel has, in a plan view, a display area and a frame area arranged around the display area; the front panel includes a design layer that overlaps the display area in a plan view, transmits at least a portion of the light incident from the liquid crystal panel, and reflects at least a portion of the light incident from the viewer side; the backlight includes, in a plan view, a third region overlapping with the display region of the liquid crystal panel, and a fourth region overlapping with the display region of the liquid crystal panel and disposed around the third region, The display device according to claim 1, wherein, when the backlight is turned on, the luminance of the fourth region is 50% or less of the luminance of the third region.

2. The backlight is a direct-type backlight having a plurality of light-emitting elements arranged in a matrix, Further, a brightness adjustment mechanism for adjusting the brightness of the backlight is provided, 2. The display device according to claim 1, wherein the brightness adjustment mechanism adjusts the emission intensity of each of the plurality of light-emitting elements in accordance with the image displayed on the liquid crystal panel.

3. the backlight is an edge-light type backlight including a light guide plate and a light emitting element disposed on a side surface of the light guide plate, The display device according to claim 1 , wherein the reflectance of the region of the light guide plate overlapping with the fourth region is lower than the reflectance of the region of the light guide plate overlapping with the third region.

4. a liquid crystal panel, a front panel disposed on a viewer's side of the liquid crystal panel, and a backlight disposed on a rear side of the liquid crystal panel; the liquid crystal panel has, in a plan view, a display area and a frame area arranged around the display area; the front panel includes a design layer that overlaps the display area in a plan view, transmits at least a portion of the light incident from the liquid crystal panel, and reflects at least a portion of the light incident from the viewer side; A display device, characterized in that the difference in luminance between the display area of ​​the liquid crystal panel in a black display state and the frame area thereof under 500 to 1000 lux is 5% or less.

5. Further, a brightness adjustment mechanism for adjusting the brightness of the backlight is provided, The display device according to claim 4, characterized in that the brightness adjustment mechanism controls the backlight to be constantly lit in a reflective display in which the pattern of the design layer is visible to the observer by reflection of light incident from the observer side.

6. 6. The display device according to claim 5, wherein the liquid crystal panel is in a transmissive state in the reflective display mode.

7. 5. The display device according to claim 1, wherein a transmittance of the area of ​​the front panel overlapping with the display area is 50% or more.

8. 5. The display device according to claim 1, wherein the front plate and the liquid crystal panel are bonded together with an optical contact layer.

9. 9. The display device according to claim 8, wherein the optical contact layer has a refractive index of 1.4 or more and 1.6 or less.

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