Display device

Abstract

To provide a display device reducing interface reflection and having high brightness.SOLUTION: A display device comprises: a display panel; and a front plate arranged on an observer side of the display panel. In plan view, the display panel includes a display area and a frame area arranged about the display area. In plan view, the front plate includes a design layer overlapping the display area, transmits at least part of light incident from the display panel, and reflects at least part of light incident from the observer side. An area of the front plate overlapping the display area has transmissivity of 50% or more. The front plate and the display panel are boned to one another with an optical adhesion layer. The optical adhesion layer has a refractive index of 1.4 or more and 1.6 or less.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 show a desired image when the display screen is turned on, studies have been conducted on ways to improve the design by making the display panel less noticeable by harmonizing it with surrounding components and housings when the display panel is turned off.

[0003] For example, 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, the second color pigment chips, and the third color pigment chips are any one of a red interference pigment, a green interference pigment, and a blue interference pigment. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5725581 Summary of the Invention [Problem to be solved by the invention]

[0005] The reflective pigment described in Patent Document 1 has the property of reflecting only light of a specific wavelength from outside light. When the pattern layer is formed on a transparent substrate, the outside light transmitted through the reflective pigment is reflected at the air interface of the transparent substrate. The observer sees a mixture of the light reflected by the reflective pigment and the light reflected at the interface of the transparent substrate (hereinafter also referred to as interface reflected light). In interface reflection, the color of the outside light is reflected almost as it is, so the interface reflected light also contains the complementary color of the color of the light reflected by the reflective pigment. Therefore, when the light reflected by the reflective pigment and the interface reflected light are mixed, the color of the reflective display may appear whitish.

[0006] Conventionally, in printed matter having a pattern layer containing an interference pigment, a smoke printed layer has been disposed on the rear side of the pattern layer in order to make the reflective display of the pattern layer appear vivid. In Fig. 11 of Patent Document 1, a light source 3 is disposed on the rear side (opposite the viewpoint) of the printed matter, and the printed matter has a transparent smoke printed layer 27 formed on the rear side of the pattern layer composed of dots containing an interference pigment.

[0007] By disposing a smoke layer, the external light that passes through the reflective pigment is absorbed by the smoke layer, reducing the interfacial reflection at the air interface of the transparent substrate, making the reflective display appear vivid. On the other hand, the smoke layer also absorbs the transmitted light emitted from the display panel side toward the viewer side, which can reduce the brightness during transmissive display. In order to increase the brightness of the transmissive display, it is necessary to increase the brightness of the backlight, etc., which poses issues such as increased power consumption and heat generation. Therefore, there is room for further study in order to achieve both a vivid reflective display and a highly luminous transmissive display.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a display device with reduced interface reflection and high brightness. [Means for solving the problem]

[0009] (1) One embodiment of the present invention is a display device comprising a display panel and a front panel arranged on the observer side of the display panel, the display panel having, in a planar view, a display area and a frame area arranged around the display area, the front panel including a design layer overlapping the display area in a planar view, transmitting at least a portion of the light incident from the display panel and reflecting at least a portion of the light incident from the observer side, the transmittance of the area of ​​the front panel overlapping with the display area being 50% or more, the front panel and the display panel being bonded together by an optical contact layer, the optical contact layer having a refractive index of 1.4 or more and 1.6 or less.

[0010] (2) Moreover, in one embodiment of the present invention, in addition to the configuration of (1) above, the display panel has a circular polarizing plate on the front panel side.

[0011] (3) Furthermore, in one embodiment of the present invention, in addition to the configuration of (1) or (2) above, the display panel is a liquid crystal panel, and the liquid crystal panel is a display device comprising, in this order, a first substrate having a first electrode, a liquid crystal layer, and a second substrate having a second electrode.

[0012] (4) Moreover, in one embodiment of the present invention, in addition to the configuration of (1) or (2) above, the display panel is a self-emitting panel.

[0013] (5) Furthermore, one embodiment of the present invention is a display device having any one of the configurations (1) to (4) above, wherein the front panel includes, in a planar view, a first region that overlaps with the display region of the display panel and a second region that is arranged around the first region, and the reflectance of the second region is 6% or more and 12% or less. Effect of the Invention

[0014] 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]

[0015] [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. 4 is a schematic cross-sectional view showing a modified example of the first embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing another modified example of the first embodiment. [Diagram 5] 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 6] FIG. 11 is a cross-sectional view showing an example of a display device according to a second embodiment. [Figure 7] FIG. 11 is a cross-sectional view showing an example of a display device according to embodiment 3. [Figure 8] 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 9] 13 is a plan view illustrating an example of a black frame layer included in the front panel of embodiment 4. FIG. [Figure 10] 10 is a schematic plan view of a first example in which a part of the second region shown in FIG. 9 is enlarged. FIG. [Figure 11] 10 is a schematic plan view of a second example in which a part of the second region shown in FIG. 9 is enlarged. FIG. [Figure 12] 10 is a schematic plan view of a third example in which a part of the second region shown in FIG. 9 is enlarged. FIG. [Figure 13] FIG. 11 is a reference diagram of a display panel for explaining black floating during transmissive display. [Figure 14] 14 is a reference diagram of a display device in which a front panel is superimposed on the display panel of FIG. 13. [Figure 15] FIG. 1 is a schematic plan view showing an example of a direct type backlight. [Figure 16] FIG. 1 is a plan view showing an example of an edge-light type backlight. [Figure 17] 17 is a graph illustrating the luminance of the third region (iii) and the fourth region (iv) of the backlight shown in FIGS. 15 and 16. [Figure 18]1 is a schematic cross-sectional view illustrating a part of the configuration and a display method of a display device according to Comparative Example 1. FIG. [Figure 19] 11 is a schematic cross-sectional view illustrating a part of the configuration and a display method of a display device according to Comparative Example 2. FIG. [Figure 20] 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

[0016] 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.

[0017] 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°.

[0018] 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.

[0019] <Embodiment 1> The display device of embodiment 1 comprises a display panel and a front panel arranged on the observer side of the display panel, the display panel having, in a planar view, a display area and a frame area arranged around the display area, the front panel including a design layer overlapping the display area in a planar view, transmitting at least a portion of the light incident from the display panel and reflecting at least a portion of the light incident from the observer side, the transmittance of the area of ​​the front panel overlapping with the display area being 50% or more, the front panel and the display panel being bonded together by an optical adhesion layer, the optical adhesion layer having a refractive index of 1.4 or more and 1.6 or less.

[0020] 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 display panel 100 and a front panel 110 arranged on the viewer's side of the display panel 100.

[0021] (Display panel) As shown in Fig. 1, the display panel 100 (100A) 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 display panel, and the inner outer edge of the black matrix 23 shown in Fig. 2 on the display 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.

[0022] In the first embodiment, a configuration is described in which a liquid crystal panel 100A is used as the display panel 100 and a backlight 200 is arranged on the back surface thereof, but the display panel 100 may be a self-emitting panel such as an LED panel having light-emitting diodes (LEDs). In this specification, when there is no particular distinction between a liquid crystal panel and a self-emitting panel, they will simply be referred to as the display panel 100.

[0023] (Liquid crystal panel) The liquid crystal panel 100A includes 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 sealed between the two substrates.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] "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.

[0031] 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.

[0032] 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)

[0033] As shown in FIG. 2, the liquid crystal panel 100A 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".

[0034] 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.

[0035] 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.

[0036] (Front plate) Front plate 110 is a member that transmits at least a portion of the light incident from display panel 100 and reflects at least a portion of the light incident from the viewer side.

[0037] The transmittance of the area of ​​the front plate 110 overlapping with the display area of ​​the display panel 100 is 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, and the display image becomes difficult to see in a bright environment. In order to make the display image more visible, it is necessary to increase the brightness of the backlight 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.

[0038] 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 example of a smoke layer with a transmittance of 70% or less is used. When a smoke layer is arranged on the back side of the front plate, it is considered that the transmittance of the front plate will be less than 50%. That is, in the display device according to this embodiment, it is preferable that a smoke layer is not arranged in an area of ​​the front plate 110 that overlaps with the display area of ​​the display panel 100.

[0039] In the display region of the display panel, the transmittance from the viewer-side surface of the display panel 100 (the viewer-side surface of the first linear polarizer 51 in FIG. 1) to the viewer-side surface of the front plate (the surface of the transparent substrate 112 in FIG. 1) is preferably 50% or more, and more preferably 70% or more.

[0040] The front panel 110 includes a design layer 111 that overlaps with the display area of ​​the display 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.

[0041] 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.

[0042] 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 display panel 100 to the viewer side.

[0043] Examples of the reflective pigment include interference pigments and metallic pigments.

[0044] 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.

[0045] 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 having a higher refractive index than the flake. 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).

[0046] 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.

[0047] 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.

[0048] The metal pieces are preferably ones that reflect visible light, and examples thereof include aluminum, nickel, titanium, stainless steel, and alloys thereof.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 3 is a schematic cross-sectional view showing a modified example of the first embodiment. As shown in FIG. 3, the front plate 110 may have a planarizing layer 114 on the rear side (display panel 100 side) of the design layer 111. When the design layer 111 is a printed layer such as a screen printed 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 plate 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 plate 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.

[0057] 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.

[0058] 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 display panel 100 in a plan view. The transparent base material 112 is preferably larger than the display area of ​​the display 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 display 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 display panel 100 and the outer edge of the black frame layer 113 may or may not match.

[0059] 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.

[0060] (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.

[0061] The front plate 110 and the display panel 100 are bonded together by the optical adhesion layer 120. That is, there is no air layer between the front plate 110 including the design layer 111 and the display panel 100. The front plate 110 and the display panel 100 are bonded together by the optical adhesion layer 120 as long as there is no air layer between the front plate 110 including the design layer 111 and the display panel 100. The front plate 110 and the display panel 100 may be in contact with the optical adhesion layer 120, or a member other than the optical adhesion layer 120, such as a transparent substrate, may be present between the front plate 110 and the display panel 100. It can also be said that the front plate 110 and the display panel 100 are integrated together by the optical adhesion layer 120.

[0062] Since there is no air layer between the front plate 110 and the display 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.

[0063] The rear surface of the front plate 110 and the front surface of the display 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.

[0064] The optical contact layer 120 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 and the polarizing plate (first linear polarizing plate 51 in FIG. 2) on the front side of the display panel. By setting the refractive index of the optical contact layer 120 to 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 a more vivid reflective display can be obtained by suppressing the interface reflected light.

[0065] 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.

[0066] 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 display panel 100 and the front plate 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.

[0067] 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 display panel can be bonded together without any air bubbles being trapped between them.

[0068] (Backlight) In the first embodiment, a backlight 200 is disposed on the rear side of the liquid crystal panel 100A. A known backlight 200 can be used, and may be, for example, an edge light type in which light sources are disposed on the end face of a light guide plate, or a direct type in which a large number of light sources are disposed within a plane and uniformity is improved using a diffusion plate or the like.

[0069] (Housing) The display device according to the first embodiment may further include a housing 300 that houses the display 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 display 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 display 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.

[0070] Fig. 4 is a schematic cross-sectional view showing another modified example of embodiment 1. As shown in Fig. 4, a black layer 302, which is a light-shielding member, may be provided on the side surface of the display 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.

[0071] 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.

[0072] <Explanation of display method> The display method of the display device according to the first embodiment will be described below with reference to FIG. 5. FIG. 5 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. 5, the unidirectional double-headed arrows and the orthogonal double-headed arrows represent the polarization state of light, and the unidirectional double-headed arrows represent linearly polarized light whose vibration direction is one direction. The orthogonal double-headed arrows represent non-polarized light. In the following, a case where the display panel is a liquid crystal panel will be illustrated. Although a case where each member is bonded together by an adhesive layer 130 will be illustrated, the adhesive layer 130 may be omitted if the members are in close contact with each other without an air layer between them.

[0073] 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 light (external light) incident on the display device from the observer side is reflected to allow the observer to view the pattern of the design layer. In this specification, transmissive display refers to a display method in which light (display light) emitted from the display panel side passes through the front plate and is emitted to the observer side, allowing the observer to view any image or the like displayed on the display panel.

[0074] When the display panel is a liquid crystal panel, 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.

[0075] 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).

[0076] As shown in FIG. 5, in the transmissive display, the light (L1) emitted from the viewer side of the liquid crystal panel 100A passes through the first linear polarizer 51 arranged on the viewer side of the liquid crystal panel 100A. 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 luminance of the light after emitting from the first linear polarizer 51 is the display panel luminance (L2) and the transmittance of the design layer 111 is α, the luminance of the light L3 emitted to the viewer side (the luminance of the display device during the transmissive display) is expressed as L2×α. Note that, although the reflection of external light, which will be described later, occurs in the transmissive display, when the amount of light emitted from the liquid crystal panel 100A 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 100A.

[0077] Next, a reflective display will be described. As shown in FIG. 5, 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 100A. A part of the light incident on the liquid crystal panel 100A is absorbed by color filters and the like inside the liquid crystal panel 100A (L6), and another part is internally reflected by members such as wiring and electrodes that constitute the liquid crystal panel 100A, and is again transmitted through the design layer 111 and 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 100A is β, the internal reflectance of the display device is α 2 ×β.

[0078] The transmittance α of the design layer 111 varies depending on the pattern formed on the design layer 111, and if the pattern is, for example, wood grain, the transmittance α is approximately 60 to 80%. The internal reflectance β of the liquid crystal panel 100A is a value obtained by subtracting the surface reflectance of the outermost surface of the liquid crystal panel 100A from the reflectance of the display area of ​​the liquid crystal panel 100A. Although it depends on the density of the color filter and the pixel design, the internal reflectance β is usually approximately 1 to 2%.

[0079] Since the display device according to the embodiment does not have a smoke layer, the luminance 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 luminance due to components other than the design layer 111. Therefore, there is no need to increase the luminance of the liquid crystal panel 100A using a backlight, and power consumption and heat generation can be reduced. In addition, since the liquid crystal panel 100A and the front plate 110 are bonded together and integrated with the optical contact layer 120, no interfacial reflection occurs between the liquid crystal panel 100A and the front plate 110. Therefore, the internal reflectance of the display device during reflective display is the product of the internal reflectance β of the liquid crystal panel 100A and the transmittance α of the design layer 111 passed twice and the internal reflectance β of the liquid crystal panel 100A (α 2The above α and β can be measured using, for example, a spectrophotometer CM-5 manufactured by Konica Minolta.

[0080] <Embodiment 2> Fig. 6 is a cross-sectional schematic diagram showing an example of a display device according to embodiment 2. As shown in Fig. 6, display device 1-B according to embodiment 2 uses liquid crystal panel 100B as a display panel, and the display panel (liquid crystal panel 100B) 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 100B, it is possible to almost eliminate the reflectance of the surface of liquid crystal panel 100B, and therefore it is possible to significantly reduce the internal reflectance.

[0081] The circular polarizer 53 is a polarizing element that converts incident light into circularly polarized light. The liquid crystal panel 100B 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.

[0082] 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.

[0083] 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°.

[0084] When the liquid crystal panel 100B 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 100B is preferably a vertical electric field type such as VA mode rather than a horizontal electric field type such as IPS.

[0085] The liquid crystal panel 100B 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.

[0086] 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.

[0087] When no voltage is applied, the liquid crystal molecules are aligned substantially vertically, so that light emitted from the backlight 200 (hereinafter, backlight light) is not transmitted to the viewer side, and the liquid crystal panel 100B 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 substantially vertical direction, so that the backlight light is transmitted to the viewer side, and the liquid crystal panel 100B is in a white display state.

[0088] <Embodiment 3> Fig. 7 is a schematic cross-sectional view showing an example of a display device according to embodiment 3. As shown in Fig. 7, a display device 1-C according to embodiment 3 uses a self-emission panel 100C as a display panel.

[0089] The self-emitting panel 100C is a panel that is equipped with a light-emitting element inside the panel and can emit light by itself, and can emit light to the observer side without requiring an external light source such as a backlight. As the self-emitting panel 100C, a known panel can be used, and an example of the panel is an OLED panel including an organic light-emitting diode (OLED).

[0090] As shown in Fig. 7, the self-emitting panel 100C may have a light-emitting layer 31. The configuration of the light-emitting diode is not particularly limited, and may include a cathode, a light-emitting layer, and an anode stacked in this order. When the light-emitting element is an OLED, the light-emitting layer 31 may contain a fluorescent material, a phosphorescent material, or the like as a light-emitting material. An electron transport layer may be disposed between the cathode and the light-emitting layer, and a hole transport layer may be disposed between the light-emitting layer and the anode.

[0091] Light-emitting elements such as OLEDs may be arranged in a matrix on the TFT substrate 10. In this case, a light-emitting element may be arranged for each TFT (pixel) arranged near the intersection of the gate wiring and the source wiring. The area where multiple light-emitting elements are arranged becomes the display area.

[0092] The plurality of light-emitting elements may include a red light-emitting element, a green light-emitting element, and a blue light-emitting element. A black matrix 23 may be disposed around each light-emitting element. When the display panel is a self-emitting panel, the black matrix 23 may be printed on the support substrate 21, or the light-emitting elements may be protected by the support substrate 21, but the support substrate 21 may not be disposed.

[0093] From the viewpoint of reducing the internal reflectance, the self-emitting panel 100C preferably has a circular polarizer on the front plate 110 side (front side). When the display panel is a self-emitting panel, display is possible even if there is no polarizer on the front side of the display panel, but as shown in Fig. 5, the self-emitting panel 100C has a circular polarizer 53 on the front plate 110 side, thereby reducing the internal reflectance. Since a self-emitting panel such as an OLED panel has a higher internal reflectance than a liquid crystal panel, it is preferable that the self-emitting panel 100C has a circular polarizer 53 on the front plate 110 side, particularly when used in a bright environment such as outdoors.

[0094] When the display device is a self-luminous panel, the transmissive display can be performed in a state where display light for displaying an arbitrary image, etc. is emitted from the self-luminous panel. The reflective display can also be performed by turning off the self-luminous panel or by turning on the self-luminous panel without displaying an arbitrary image, etc., and lowering the luminance of the self-luminous panel to a degree that the pattern, etc. of the design layer can be visually recognized by an observer by the reflected light.

[0095] <Embodiment 4> Fig. 8 is a schematic plan view of a display device in which the boundary between the display area and frame area of ​​a liquid crystal panel and the outer edge of a black frame layer are overlapped. Fig. 9 is a schematic plan view showing an example of a black frame layer included in a front panel in embodiment 4. In Figs. 8 and 9, the dotted line indicates the boundary between the display area and frame area of ​​the display panel, and the dashed-dotted line corresponds to the inner outer edge of black frame layer 113 shown in Fig. 2 on the display panel side.

[0096] Even when the display 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. In the fourth embodiment, the reflectance of the front panel in the area that overlaps with the frame area of ​​the display panel is adjusted, so that the boundary between the display area and the frame area is less noticeable even when the display device is observed from an oblique direction.

[0097] 9, in the display device according to the fourth embodiment, front panel 110 includes, in a plan view, a first region (i) that overlaps with the display region of the display panel, and a second region (ii) that is disposed around the first region (i). Note that second region (ii) of front panel 110 may partially overlap with the frame region of the display panel in a plan view, or may not coincide with the frame region.

[0098] 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 display 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 display 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.

[0099] 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.

[0100] The second region (ii) preferably has a reflectance that increases from the inner periphery of the display panel toward the first region (i). Specifically, in a plan view, the black frame layer 113 is preferably disposed on the rear side of the design layer 111 of the front panel 110 and in an area that overlaps with the frame area of ​​the display 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).

[0101] 10 to 12 are schematic plan views of first to third examples in which a part of the second region shown in FIG. 9 is enlarged. FIGS. 10 to 12 correspond to the part surrounded by the two-dot chain line in FIGS. 8 and 9. 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. 10, the shade of the black frame layer 113 may be changed continuously, as shown in FIG. 11, the shade of the black frame layer 113 may be changed stepwise, or as shown in FIG. 12, the area of ​​the dots may be reduced toward the first region (i) to change the shade of the black frame layer 113.

[0102] <Backlight configuration> The display panel is a liquid crystal panel, and further, for a display device having a backlight on the rear side of the liquid crystal panel, the following describes a configuration of the backlight that makes it difficult to see the boundary between the display area and the frame area during transmissive display.

[0103] The black floating phenomenon will be described with reference to Fig. 13 and Fig. 14. Fig. 13 is a reference diagram of a display panel for explaining the black floating phenomenon during transmissive display. Fig. 14 is a reference diagram of a display device in which a front panel is superimposed on the display panel of Fig. 13.

[0104] When the display panel is a liquid crystal panel, black floating may be observed even when black is displayed in the display area. As shown in FIG. 13, an example is shown in which the alphabet A is displayed in white in the display area of ​​the display panel, with the background of the characters displayed in black. Since the liquid crystal panel transmits a small amount of backlight light 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 2This difference is noticeable as a difference from the black of the frame area. Even if a front panel is placed on an LCD panel with such a black floating area as shown in Figure 14, the boundary between the display area and the frame area will be visible during transmissive display.

[0105] When the backlight is turned on, the luminance of the fourth region (iv) overlapping with the frame region of the liquid crystal panel is preferably 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.

[0106] The backlight may be a direct type backlight or an edge light type backlight. FIG. 15 is a plan view schematic diagram showing an example of a direct type backlight. FIG. 16 is a plan view schematic diagram showing an example of an edge light type backlight. In FIG. 15 and FIG. 16, for reference, the positions of the display area and frame area of ​​the display panel are indicated by two-dot chain lines. As shown in FIG. 15 and FIG. 16, 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).

[0107] 15, 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.

[0108] As the light emitting element 201, any element known in the field of backlights can be used, such as a light emitting diode (LED).

[0109] 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 100A. 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 100A is also called partial driving (local dimming).

[0110] 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. 15 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 100A displays black, the light-emitting elements 201 overlapping the region displaying black can be turned off to suppress floating black.

[0111] 16, 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.

[0112] 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.

[0113] 16, 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.

[0114] 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).

[0115] Fig. 17 is a graph illustrating the luminance of the third region (iii) and the fourth region (iv) of the backlight shown in Fig. 15 and Fig. 16. As shown in Fig. 17, 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.

[0116] <Backlight driving method> In a display device in which the display panel is a liquid crystal panel and further includes a backlight on the rear side of the liquid crystal panel, it is preferable that 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 be 5% or less under 500 to 1000 lux.

[0117] By making the difference in luminance between the display area of ​​the liquid crystal panel in the black display state and the frame area approximately the same (5% or less) in a bright room (500 to 1000 lux), the boundary between the display area of ​​the liquid crystal panel and the frame area can be made less visible. As shown in Figure 2, when black frame layer 113 is disposed on the rear side of design layer 111 of front panel 110, the reflectance of the frame area overlapping with black frame layer 113 is approximately 6 to 12%.

[0118] The backlight is not particularly limited, and may be a direct-light type backlight or an edge-light type backlight. By making the difference in luminance between the display area of ​​the liquid crystal panel in a black display state and the frame area substantially the same, the boundary between the display area and the frame area of ​​the liquid crystal panel can be made less visible without using a backlight having areas with different luminance as described above.

[0119] 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.

[0120] The display device may further include a brightness adjustment mechanism for adjusting the brightness of the backlight, and the brightness adjustment mechanism may control 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 display panel is not in use), the boundary between the display area and the frame area of ​​the liquid crystal panel can be made less visible.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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).

[0125] The display device according to the embodiment may be used, for example, as an instrument panel of an automobile to display instruments such as a speedometer, or may be used as an operation panel of a home appliance. EXAMPLES

[0126] The effects of the present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0127] Example 1 The display device 1 of Example 1 corresponds to a specific example of the display device 1 according to the above-mentioned embodiment 1, and has the configuration shown in Figures 1 and 2. A VA mode liquid crystal panel sandwiched between a pair of linear polarizers was used as the display panel. The pair of linear polarizers were arranged so that the transmission axes were perpendicular to each other.

[0128] As shown in Fig. 5, the transmittance of the design layer 111 is α, and the internal reflectance of the liquid crystal panel is β. Note that 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.

[0129] The luminance of the light L3 emitted to the viewer side during transmissive display is L2×α, where the luminance of the light after it has exited the first linear polarizer 51 is L2, as described above. With respect to the internally reflected light L7 during reflective display, the internal reflectance of the display device is approximately α 2 ×β In the first embodiment, since liquid crystal panel 100A and front plate 110 are bonded together with optical contact layer 120, no interface reflection occurs between liquid crystal panel 100A and front plate 110.

[0130] Comparative Example 1 18 is a schematic cross-sectional view illustrating a part of the configuration and a display method of a display device according to Comparative Example 1. A display device 1001 of Comparative Example 1 has the same configuration as that of Example 1, except that a liquid crystal panel 100A and a front plate 110 are not bonded together with an optical contact layer 120, and an air layer 400 is provided between the liquid crystal panel 100A and the front plate 110.

[0131] As shown in FIG. 18, the luminance of light L3 emitted to the viewer side during transmissive display is L2×α, similar to the first embodiment.

[0132] 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 display panel are the same as in Example 1, so a description thereof will be omitted. Comparative Example 1 has an air layer 400 between the liquid crystal panel 100A and the front plate 110, so part of the external light L4 is reflected at the interface between the front plate 110 and the air layer 400 (L7-1). Part of the external light L4 incident on the display panel is internally reflected by the members constituting the display 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 Comparative Example 1 is approximately y×α 2 +α 2 ×β.

[0133] Comparative Example 2 19 is a schematic cross-sectional view illustrating a part of the configuration and the display method of the display device according to Comparative Example 2. The display device 1002 of Comparative Example 2 has the same configuration as Example 1, except that the liquid crystal panel 100A 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 100A and the front plate 110, and a smoke layer 401 is disposed on the rear side of the design layer 111.

[0134] 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.

[0135] As shown in FIG. 19, in comparative example 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.

[0136] 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 display panel are the same as in Example 1, so a description thereof will be omitted. Comparative Example 2 has an air layer 400 between the liquid crystal panel 100A and the front plate 110, so 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 display panel is internally reflected by the members constituting the display 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 Comparative Example 2 is approximately z×α 2 ×γ 2 +α 2 ×β.

[0137] 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 Example 1 and Comparative Examples 1 and 2, assuming α=70%, β=1.5%, and γ=70%, and the results are summarized in the following Table 1. The above α, β, and γ can be measured using a spectrophotometer CM-5 manufactured by Konica Minolta.

[0138] [Table 1]

[0139] As shown in Table 1, in Example 1, the internal reflectance of the display device was low at 0.7%, so that in the reflective display, the pattern of the design layer looked vivid without being whitish. In addition, in the transmissive display, the display image could be displayed without being dark, because the luminance of L3 was also high.

[0140] On the other hand, the internal reflectance of the display device in Comparative Example 1 was high at 2.7%, and reflected more external light than in Example 1, making the design layer pattern appear whitish. In Comparative Example 2, external light reflection was suppressed more than in Comparative Example 1, but the luminance of L3 was 49%, and the displayed image was dark in the transmissive display.

[0141] FIG. 20 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. 20 illustrates a case where the normal direction of a 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 Example 1 and Comparative Examples 2 and 3 is larger than when observed from the normal direction.

[0142] Example 2 Example 2 is a specific example of embodiment 2. A VA mode liquid crystal panel was used as the display panel. The liquid crystal panel has a circular polarizer 53 on the front side and a circular polarizer 54 on the rear side. Referring to FIG. 5, the display device of Example 2 has the same configuration as Example 1, except that the polarizers on the front side and rear side of the liquid crystal panel are circular polarizers.

[0143] Comparative Example 3 Comparative Example 3 differs from Example 2 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. Referring to Fig. 18, the display device of Comparative Example 3 has the same configuration as Comparative Example 1, except that the first linear polarizer 51 on the front side of the liquid crystal panel is replaced with a circular polarizer.

[0144] Comparative Example 4 Comparative Example 4 differs from Example 2 in that the liquid crystal panel and the front panel are not bonded together with an optical contact layer, there is an air layer between the liquid crystal panel and the front panel, and a smoke layer is disposed on the rear side of the design layer. Referring to Fig. 19, the display device of Comparative Example 4 has the same configuration as Comparative Example 2, except that the first linear polarizer 51 on the front side of the liquid crystal panel is replaced with a circular polarizer.

[0145] In Example 2 and Comparative Examples 3 and 4, a circular polarizer was used, and therefore the internal reflectance β of the liquid crystal panel was lower, β=0.5%, than in Example 1. The luminance of light L3 emitted to the viewer side during transmissive display in Example 2 and Comparative Examples 3 and 4, and the internal reflectance of the display device during reflective display were calculated assuming α=70%, β=0.5% and γ=70%, and the results are summarized in Table 2 below.

[0146] [Table 2]

[0147] The internal reflectance of the display device in the second embodiment during reflective display was 0.2%, making it possible to achieve a more vivid reflective display than in the first embodiment.

[0148] Example 3 Example 3 is a specific example of embodiment 3. Referring to Fig. 5, the display device of Example 3 has the same configuration as Example 1, except that an LED panel is used as a display panel, and the LED panel does not have a polarizing plate on the back side, but has a circular polarizing plate 53 on the front side.

[0149] Comparative Example 5 Comparative Example 5 differs from Example 3 in that the LED panel and the front plate are not bonded with an optical adhesion layer, and an air layer is provided between the LED panel and the front plate. Referring to Fig. 18, the display device of Comparative Example 5 has the same configuration as Comparative Example 1, except that the LED panel is used as the display panel, and the LED panel does not have a polarizing plate on the back side, but has a circular polarizing plate 53 on the front side.

[0150] Comparative Example 6 Comparative Example 6 differs from Example 3 in that the LED panel and the front panel are not bonded with an optical adhesion layer, there is an air layer between the LED panel and the front panel, and a smoke layer is disposed on the back side of the design layer. Referring to Fig. 19, the display device of Comparative Example 6 has the same configuration as Comparative Example 2, except that the LED panel is used as the display panel, and the LED panel does not have a polarizing plate on the back side but has a circular polarizing plate 53 on the front side.

[0151] In Example 3 and Comparative Examples 5 and 6, a circular polarizer was used, and therefore the internal reflectance β of the display panel was lower, β=0.5%, than in Example 1. The luminance of light L3 emitted to the viewer side during transmissive display in Example 3 and Comparative Examples 5 and 6 and the internal reflectance of the display device during reflective display were calculated assuming α=70%, β=0.5% and γ=70%, and the results are summarized in Table 3 below.

[0152] [Table 3]

[0153] In the display device of Example 3, even when the display panel is an LED panel, by arranging a circular polarizer on the front side, it is possible to obtain an internal reflectance equivalent to that of Example 2, and to achieve a reflective display that is even more vivid than that of Example 1. [Explanation of symbols]

[0154] 1-A, 1-B, 1-C, 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 31: Light-emitting layer 40: Sealing material 51: First linear polarizing plate 52: Second linear polarizer 53, 54: Circular polarizing plate 100: Display panel 100A, 100B: Display panel (liquid crystal panel) 100C: Display panel (self-luminous 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 display panel and a front panel disposed on a viewer side of the display panel, the display panel has, in a plan view, a display area and a frame area arranged around the display area; the front plate includes a design layer that overlaps the display area in a plan view, transmits at least a portion of the light incident from the display panel, and reflects at least a portion of the light incident from the viewer side; The transmittance of the region of the front panel overlapping with the display region is 50% or more; the front plate and the display panel are bonded together by an optical contact layer, The display device, wherein the optical contact layer has a refractive index of 1.4 or more and 1.6 or less.

2. The display device according to claim 1 , wherein the display panel has a circular polarizing plate on the front plate side.

3. the display panel is a liquid crystal panel, 3. The display device according to claim 2, wherein the liquid crystal panel comprises, in this order, a first substrate having a first electrode, a liquid crystal layer, and a second substrate having a second electrode.

4. 3. The display device according to claim 2, wherein the display panel is a self-luminous panel.

5. the front panel includes, in a plan view, a first region overlapping the display region of the display panel and a second region disposed around the first region; The display device according to claim 1 , wherein the reflectance of the second region is not less than 6% and not more than 12%.

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