Indication 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, studies have been conducted on display devices that display a desired image when the display screen is turned on, by making the display panel, such as a liquid crystal panel, less noticeable when the panel is turned off, so as to harmonize with surrounding components, a housing, etc. As a method for making the display screen less noticeable when the panel is turned off, for example, methods have been considered 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 comprises a first color binder and a plurality of first color pigment chips dispersed within the first color binder; each of the second color dots comprises a second color binder and a plurality of second color pigment chips dispersed within the second color binder; and each of the third color dots comprises a third color binder and a plurality of third color pigment chips dispersed within the third color binder; and wherein each of the first color pigment chips, second color pigment chips, and third color pigment chips is 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, which comprises 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 the pitch of the transmissive portions is larger than the pitch of the pixels on the display surface. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5725581 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-331132 [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 may 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 inconspicuous 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 viewer side of the liquid crystal panel, and a backlight arranged on the back 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 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 viewer side, the backlight includes, in a planar view, a third area that overlaps the display area of ​​the liquid crystal panel and a fourth area that overlaps the display area of ​​the liquid crystal panel and is arranged around the third area, and when the backlight is turned on, the brightness of the fourth area is 50% or less of the brightness 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 light emission intensity of each of the plurality of light-emitting elements according to 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 the area of ​​the light guide plate that overlaps with the fourth area is lower than the reflectance of the area of ​​the light guide plate that overlaps with the third area.

[0012] (4) Another embodiment of the present invention is a display device comprising a liquid crystal panel, a front panel arranged on the viewer 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 viewer 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 under 500 to 1000 lux is 5% or less.

[0013] (5) Furthermore, in addition to the configuration of (4), one embodiment of the present invention further comprises 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 visible to the observer by reflecting light incident from the observer side.

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

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

[0016] (8) Furthermore, in one embodiment of the present invention, in addition to the configuration of any one of (1) to (7) above, the front panel and the liquid crystal panel are bonded together by an optical contact layer.

[0017] (9) Furthermore, in one embodiment of the present invention, in addition to the configuration of (8), the optical contact layer has a refractive index of 1.4 or more and 1.6 or less. [Effects 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 explanation of the drawings]

[0019] [Figure 1] 1 is a plan view schematically illustrating an example of a display device according to Embodiment 1. FIG. [Figure 2] FIG. 2 is a cross-sectional view taken along line X1-X2 in FIG. [Figure 3] FIG. 10 is a reference diagram of a liquid crystal panel for explaining floating black 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. [Figure 5] FIG. 2 is a plan view schematically illustrating a direct-type backlight used in the first embodiment. [Figure 6] FIG. 2 is a plan view schematically illustrating an edge-light type backlight used in the first embodiment. [Figure 7] 10 is a graph illustrating the luminance of a third region (iii) and a fourth region (iv) in the first embodiment. [Figure 8] FIG. 10 is a cross-sectional view schematically illustrating a display device 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 area and frame area of ​​a liquid crystal panel and the outer edge of a black frame layer are overlapped. [Figure 10] FIG. 2 is a plan view schematically illustrating 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] 10 is a cross-sectional view of a display device illustrating an example in which a black layer is provided on the side surface of the liquid crystal panel and / or the inner wall of the housing. FIG. [Figure 15] 1 is a 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. 10 is a cross-sectional view showing an example of a display device according to a third embodiment. [Figure 17] 1 is a cross-sectional view illustrating a part of the configuration of a display device according to a first embodiment and a display method. [Figure 18] 10 is a cross-sectional view illustrating a part of the configuration of a display device according to a second embodiment and a display method. FIG. [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 INVENTION

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

[0021] In this specification, "two directions are orthogonal" means that 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°. "Two directions are parallel" means that 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 "viewer side" refers to the side from which the viewer views the display device, and is also referred to as the "front side." The term "rear side" refers to the side opposite the viewer side.

[0023] <Embodiment 1> A display device according to a first embodiment includes a liquid crystal panel, a front panel disposed on the viewer's side of the liquid crystal panel, and a backlight disposed on the rear side of the liquid crystal panel, wherein the liquid crystal panel has, in a plan view, a display area and a frame area disposed around the display area, the front panel includes a design layer overlapping the display area in a plan view, and transmits at least a portion of light incident from the liquid crystal panel and reflects at least a portion of light incident from the viewer's side, the backlight includes, in a plan view, a third area overlapping the display area of ​​the liquid crystal panel and a fourth area overlapping the display area of ​​the liquid crystal panel and disposed around the third area, wherein the luminance of the fourth area is 50% or less of the luminance of the third area when the backlight is turned on. 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 schematically showing an example of a display device according to embodiment 1. Fig. 2 is a cross-sectional view schematically showing the display device according to embodiment 1 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 panel 110 disposed on the viewer's side of the liquid crystal panel 100, and a backlight 200 disposed on the rear side of the liquid crystal panel 100. The configurations of the liquid crystal panel 100 and the front panel 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 outer edge of the black matrix 23 on the inner side of the liquid crystal panel shown in Fig. 2 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, etc. is displayed during transmissive display. The frame area is an area that overlaps with the housing and bezel, and is not involved in transmissive display.

[0026] Below, we will explain black floating with reference to Figures 3 and 4. Figure 3 is a reference diagram of a liquid crystal panel to explain black floating during transmissive display. Figure 4 is a reference diagram of a display device in which a front panel is superimposed on the liquid crystal panel of Figure 3.

[0027] Even when black is displayed in the display area of ​​a liquid crystal panel, black floating can be observed. As shown in Figure 3, an example is shown in which the letter 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 liquid crystal panel transmits a small amount of backlight light even in the black display state, the black in the display area can 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 brightness of the backlight. To explain in concrete terms, the transmittance of a liquid crystal panel in the black display state is usually around 0.006%, and if the brightness of the backlight is set to 10,000 cd / m 2 So the black level is 0.6cd / m 2 This difference is noticeable as a difference from the black of the frame area. Even if a front panel is placed over such a black LCD panel 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 brightness of the fourth region (iv) overlapping with the frame region of the liquid crystal panel is 50% or less of the brightness 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 less visible when the liquid crystal panel is in transmissive display mode.

[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 embodiment 1. FIG. 6 is a plan view schematic diagram of an edge-light-type backlight used in embodiment 1. 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, backlights 200A and 200B each include a third area (iii) and a fourth area (iv) that overlap 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 that adjusts the brightness of the backlight, and the brightness adjustment mechanism preferably adjusts the light emission intensity of each of the plurality of light-emitting elements 201 in accordance with the image displayed on the liquid crystal panel 100. A driving method that adjusts the light emission intensity of each of the plurality of light-emitting elements 201 in accordance with the image displayed on the liquid crystal panel 100 is also called partial driving (local dimming).

[0033] 5, 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) so that the brightness of the fourth region of the backlight 200A is 50% or less of the brightness of the third region. Furthermore, when the image displayed on the liquid crystal panel 100 displays black, floating black can be suppressed by turning off the light-emitting elements 201 that overlap the region where black is displayed.

[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 surfaces of the light guide plate 203. Although not shown, the backlight 200B may further include a reflective sheet, a diffusion film, etc.

[0035] There are no particular limitations 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 allow light incident from the light emitting elements 201 arranged on the side surface to be emitted toward the viewer.

[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] 7 is a graph illustrating the brightness of the third region (iii) and the fourth region (iv) in embodiment 1. As shown in FIG. 7, the brightness is highest in the center of the third region (iii), and is lower outside the fourth region (iv). On the edge The brightness may decrease toward the third region (iii). There may not be a clear boundary of brightness at the boundary between the third region (iii) and the fourth region (iv), and it is preferable that the brightness changes gradually. If the maximum brightness of the third region (iii) is 100%, the brightness at the boundary between the third region (iii) and the fourth region (iv) is preferably 50% or less.

[0039] (LCD 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 sealed between the two substrates.

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

[0041] The pixel electrode and the counter electrode described later may be transparent electrodes, and can 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 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 materials in the field of liquid crystal panels can be used.

[0044] The support 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 or 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 no 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 arranged on the TFT substrate side, and in the horizontal electric field method, the counter electrode is arranged 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 polarizers may be absorption-type linear polarizers that have a transmission axis that transmits only light of a specific polarization direction and an absorption axis that is 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. Known polarizers can be used as the first and second linear polarizers 51 and 52, 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 using 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 using 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 panel 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 the display area of ​​the liquid crystal panel 100 is preferably 50% or more. The display device according to embodiment 1 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 will be significantly reduced, making the displayed image difficult to see in bright environments. To make the displayed image more visible, the brightness of the backlight must be increased to increase the brightness of the display device, resulting in increased backlight power consumption. 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, transmittance refers to total light transmittance, which is measured according to JIS K 7361-1. The total light transmittance can be measured using, for example, a turbidity meter such as the HazeMeter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.

[0054] Conventionally, for example, the printed matter described in Patent Document 1 has had a smoke layer, such as a transmissive smoke print layer, disposed on the back side to suppress interface reflection. The smoke layer is a low-transmittance layer 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 disposed on the back side of the front panel, the transmittance of the front panel is considered to be less than 50%. It is preferable that a smoke layer is not disposed in the area of ​​front panel 110 that overlaps with the display area of ​​liquid crystal panel 100. If the smoke layer is not disposed, the transmittance of the area of ​​front panel 110 that overlaps with the display area of ​​liquid crystal panel 100 can be said to be 50% or more.

[0055] In the display area 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 Figure 1) to the viewer-side surface of the front panel (the surface of the transparent substrate 112 in Figure 1) is preferably 50% or more, and more preferably 70% or more.

[0056] The front panel 110 includes a design layer 111 that overlaps 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 visible to the viewer. 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 specific wavelengths of external light toward the viewer, and can cause the viewer to see 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 by additively mixing the reflected light from the reflective pigments of multiple colors, the viewer can see 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] Interference pigments, also known as pearl pigments, may reflect light of a specific wavelength and transmit light of wavelengths other than the specific wavelength. Examples of the interference pigment include those having a substrate and a coating layer covering the substrate.

[0061] The substrate may be a thin 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 thin flakes. The interference pigment may be dispersed in a binder resin and applied to a base film. The color of the interference light perceived by the observer can be adjusted by changing the thickness of the coating layer. Examples of the interference pigment that can be used include those listed in Patent Document 1 (Japanese Patent 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 at the interface between the coating layer and the substrate. Another part of the external light passes through the substrate and is reflected by the surface of the base film. To the observer, this reflected light is combined and perceived as interference light of a specific pearlescent 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 those that reflect visible light, and examples thereof include aluminum, nickel, titanium, stainless steel, and alloys thereof.

[0065] The pigment coating the metal flakes 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] Other forms of the design layer 111 include, for example, a screen having a plurality of fine holes, or a decorative film having a plurality of transparent portions on which a specific pattern is formed, as described in Patent Documents 2 and 3 above.

[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 over 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 high transmittance, for example, a transmittance of 90% or more. Furthermore, from the viewpoint of preventing the displayed image from becoming blurred, 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 such as the 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 Figure 2, when the design layer 111 is placed on the back side of the transparent substrate 112, scratches on the design layer 111 can be prevented. 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 sense of depth and gloss may make the texture appear inferior. From the perspective of being able to more vividly express the texture of the design layer 111, it is preferable that the design layer 111 be placed on the front side of the transparent substrate 112. On the other hand, when the design layer 111 is placed on the front side of the transparent substrate 112, the design layer 111 is easily scratched, so a hard coat layer (not shown) may also be provided on the front side of the design layer 111.

[0074] The hard coat layer preferably has high transparency and scratch resistance, and examples thereof include a coating layer made 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 cross-sectional schematic diagram of a display device illustrating an example in which the front panel has a planarizing layer. As shown in FIG. 8, front panel 110 may have planarizing layer 114 on the rear side (liquid crystal panel 100 side) of design layer 111. If design layer 111 is a printed layer such as screen printing, unevenness of about 5 to 10 μm may exist depending on the pattern of design layer 111. If the printed layer has unevenness, tiny air bubbles may be trapped between front panel 110 and optical contact layer 120, making the reflective display difficult to see. By providing planarizing layer 114 and making the surface of front panel 110 facing optical contact layer 120 flat (for example, 3 μm or less), the unevenness can be made less susceptible to air bubbles, making the reflective display appear 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 can be formed by printing or other methods using 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-blocking layer and is preferably disposed in a region overlapping the liquid crystal panel 100 in a planar view. The transparent substrate 112 is preferably larger than the display region of the liquid crystal panel 100, and the black frame layer 113 may be disposed in a region (frame region) where the transparent substrate 112 extends beyond the display region. The black frame layer 113 blocks stray light from the liquid crystal panel 100, making the design layer 111 appear vivid. The black frame layer 113 also prevents a bezel, frame, etc. from being visible to the viewer. 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 coincide with each other.

[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 a black pigment. The black frame layer 113 may be solid printed so that the transmittance is approximately uniform, or may be gradation printed as described below. Black tape may also be used.

[0079] Fig. 9 is a schematic plan view of a display device, showing the boundary between the display area and frame area of ​​a liquid crystal panel and the outer edge of a black frame layer superimposed on each other. 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-dotted line corresponds to the outer edge of black frame layer 113 on the inner side of the liquid crystal panel, as 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 viewed 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 viewed from an oblique direction.

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

[0082] The reflectance of the second region (ii) is preferably 6% or more and 12% or less. The first region (i) of the front panel 110 overlaps the display region of the liquid crystal panel in a planar view, and a design layer 111 is disposed therein. If the design layer 111 contains a reflective pigment, the reflectance of the first region (i) of the front panel 110 may be approximately 10% or more. As shown in FIG. 2, a black frame layer 113 may be disposed in the region overlapping with the frame region of the liquid crystal panel, but the black frame layer 113 is typically a light-blocking material and has a reflectance of approximately 0%. By disposing the second region (ii) having a reflectance of 6% or more and 12% or less around the first region (i) of the front panel 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 reflectance of the second region (ii) preferably increases from the inner periphery of the liquid crystal 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 101 in an area overlapping the frame region 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, respectively, 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 in steps, or the shade of the black frame layer 113 may be changed by reducing the area of ​​the dots toward the first region (i) as shown in Fig. 13.

[0086] (Optical adhesion layer) The optical contact layer 120 is a transparent adhesive layer or bonding layer used to bond 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 an optical adhesion layer 120. It can also be said that the front plate 110 and the liquid crystal panel 100 are integrated by the optical adhesion layer 120. The fact that the front plate 110 and the liquid crystal panel 100 are bonded together by the optical adhesion layer 120 means that there is no air layer between the front plate 110 including the design layer 111 and the liquid crystal panel 100, and the front plate 110 and the liquid crystal panel 100 may each 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 liquid crystal panel 100.

[0088] Since there is no air layer between the front panel 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 colors of the pattern of the design layer 111 do not appear whitish in reflective display, and clear, vivid colors can be viewed. The display device 1-A according to the first embodiment can achieve vivid reflective display without disposing a semi-transparent smoke layer such as the transmissive smoke print layer of Patent Document 1. Furthermore, since the display device according to the embodiment does not have a smoke layer, it can achieve both vivid reflective display and highly luminous transmissive display without reducing the brightness in 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 adhesion layer 120. The optical adhesion layer 120 may be a single layer or may be a laminate of multiple optical adhesion 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 (the refractive index of air at 0°C and 1 atmosphere), and is preferably greater than the refractive index of the transparent substrate 112 or the front-side polarizer of the liquid crystal panel (first linear polarizer 51 in FIG. 2). 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 prevent light transmitted through the design layer 111 from being reflected at an interface and returning to the viewer. The interface reflected light of the transmitted light transmitted through the design layer 111 is in a complementary color relationship with the light reflected by the design layer 111, and therefore, 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, even when the design layer 111 is disposed on the back side of the front panel 110, the thickness of the optical adhesion layer 120 is preferably 200 μm or more. By making the thickness of the optical adhesion 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 trapping air bubbles 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. Double-sided tape 301 may be placed on the back side of the front plate 110 that overlaps the frame area (on the back side of the black frame layer 113 in FIG. 2 ) to fix it 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 housed 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 also not limited to the shape shown in FIG. 2 .

[0095] 14 is a cross-sectional view of a display device illustrating an example in which 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-blocking 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 black light-shielding tape or black sponge. From the viewpoint of also obtaining the effect of protecting the display device from impact, it is preferable to provide the cushioning material.

[0097] <Explanation of display method> A display method of the display device according to embodiment 1 will be described below with reference to FIG. 15. FIG. 15 is a cross-sectional schematic diagram illustrating a portion of the configuration of the display device according to embodiment 1 and the display method. In FIG. 15, unidirectional double-headed arrows and orthogonal double-headed arrows represent the polarization state of light, and the unidirectional double-headed arrows represent linearly polarized light, which vibrates in one direction. The orthogonal double-headed arrows represent unpolarized light. In the following, a case where each component is bonded together with an adhesive layer 130 will be exemplified, but adhesive layer 130 may be omitted as long as the components are in close contact with each other without any air gap 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 light (external light) incident on the display device from the viewer's side is reflected, allowing the viewer 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 liquid crystal panel side passes through the front plate and is emitted to the viewer's side, allowing the viewer to view any image displayed on the liquid crystal panel.

[0099] Transmissive display can be achieved by turning on the backlight when the liquid crystal panel is in a white display state. Reflective display can be achieved when the liquid crystal panel is in a black display state and the backlight is on or off. 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 seen by an observer through reflected light.

[0100] The black display state refers to a state in which the alignment 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 alignment 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, allowing light emitted from a backlight to be transmitted to the viewer side. When the alignment 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 transmissive display, light (L1) emitted from the viewer side of the liquid crystal panel 100 passes through the first linear polarizer 51 disposed 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 toward the viewer side. If the luminance of the light after emitting from the first linear polarizer 51 is the liquid crystal panel luminance (L2) and the transmittance of the design layer 111 is α, the luminance of light L3 emitted toward the viewer side (the luminance of the display device in transmissive display) is expressed as L2 × α. Note that, although external light reflection, which will be described later, occurs in transmissive display, if the light emitted from the liquid crystal panel 100 side is sufficiently greater than the external light, the viewer will find it difficult to see the pattern of the design layer, and will be able to see any image displayed on the liquid crystal panel 100.

[0102] Next, reflective display will be described. As shown in FIG. 15, if light incident on the display device from the viewer side is external light L4, a portion of L4 passes through the transparent substrate 112, is reflected by the design layer 111, and is emitted to the viewer side (L5). Another portion 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 portion of the light incident on the liquid crystal panel 100 is absorbed by color filters and the like inside the liquid crystal panel 100 (L6), and another portion is internally reflected by components 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 will be 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 approximately 60 to 80%. The internal reflectance β of the liquid crystal panel 100 is the reflectance of the display area of ​​the liquid crystal panel 100 minus the surface reflectance of the outermost surface of the liquid crystal panel 100. Although it depends on factors such as the density of the color filters and pixel design, the internal reflectance β is typically approximately 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 using a backlight, which makes it possible to reduce power consumption and heat generation. In addition, it is preferable that the liquid crystal panel 100 and the front plate 110 are bonded together with an optical adhesion layer 120 and integrated. 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 (α) 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. 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 examined below using reference forms.

[0106] <Reference form 1> 17 is a cross-sectional schematic diagram illustrating a part of the configuration and display method of a display device according to Reference Form 1. A display device 1001 of Reference Form 1 has the same configuration as that shown in 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 explanation using FIG.

[0108] Regarding reflective display, the reflected light L5 of 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, and therefore will not be explained again. Since the reference form 1 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 front plate 110 and the air layer 400 (L7-1). 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> 18 is a cross-sectional schematic diagram illustrating a part of the configuration and display method of a display device according to Reference Form 2. A display device 1002 of Reference Form 2 has the same configuration as that shown in 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 back side of the design layer 111.

[0110] The smoke layer 401 can be formed by coating the back side of the front panel with a resin composition in which a black pigment is mixed with a transparent resin. 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 brightness of light L3 emitted toward the viewer during transmissive display is L2×α×γ.

[0112] Regarding reflective display, the reflected light L5 of 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, and therefore will not be explained again. 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 toward the viewer (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] With α=70%, β=1.5%, and γ=70%, the luminance of light L3 emitted toward the viewer during transmissive display and the internal reflectance of the display device during reflective display were calculated for the configuration of Figure 2 and reference forms 1 and 2, 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 in reflective display, the design layer pattern is vivid and does not appear whitish. In addition, the brightness of L3 is high, so in transmissive display, the displayed image does not appear 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 Figure 2, making the design layer pattern appear whitish. Reference Form 2 suppresses external light reflection more than Reference Form 1, but the L3 luminance 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 equation and is a function of the refractive index of the medium and the angle of incidence. FIG. 19 illustrates a case where the normal direction of a medium such as a substrate is set to 0°, and the interface reflectance at an incident angle of 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 greater 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's side of the liquid crystal panel, and a backlight disposed on the rear side of the liquid crystal panel, wherein the liquid crystal panel has, in a plan view, a display area and a frame area disposed around the display area, the front panel includes a design layer overlapping the display area in a plan view, and transmits at least a portion of light incident from the liquid crystal panel and reflects at least a portion of light incident from the viewer's side, and the 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, by controlling the backlight, the boundary between the display area and the frame area during transmissive display can be made less visible.

[0119] In embodiment 2, by making the difference in luminance between the display area of ​​the liquid crystal panel in a 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 and the frame area of ​​the liquid crystal panel can be made less visible. Note that, as shown in Figure 2, when black frame layer 113 is disposed on the back 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%.

[0120] The configuration of the front panel 110 other than the black frame layer 113 can be the same as in embodiment 1, so a duplicated description will be omitted. Also, the liquid crystal panel can be the same as that used in embodiment 1, so a duplicated description will be omitted.

[0121] The backlight used in embodiment 2 is not particularly limited and can be a known one, and can be, for example, an edge-light type in which a light source is arranged on the edge surface 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 diffuser plate, etc. According to embodiment 2, it is possible to make the boundary between the display area and the frame area of ​​the liquid crystal panel less visible without using a backlight having areas with different luminance as in embodiment 1.

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

[0123] In a first configuration of embodiment 2, the display device further includes a brightness adjustment mechanism that adjusts 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 visible to the viewer by reflection of light incident from the viewer 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 less visible.

[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 (in which the liquid crystal panel is in a transmissive state for the backlight is always on) is preferable.

[0125] The above-mentioned transmission 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 faintly lit. The faintly lit backlight means, for example, that the brightness of the backlight is, for example, 5 to 10 cd / m 2 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 The driving method (driving method A) is to light up the LCD panel in the black display state with a transmittance of δ% and turn on the backlight at 6.7 cd / m 2 This method achieves the same brightness as the driving method (driving method B) in which the LCD panel is turned on at 1500×δ% and the white display state is displayed at a transmittance of 1500×δ%. In other words, by using driving method B, the same effect (brightness) can be achieved with approximately 1 / 1500 of the power consumption of driving method A. Driving method B is a driving method that is particularly effective for smartphones and other devices that are powered by batteries.

[0127] When the above driving method A and driving method B are calculated using more specific transmittance, the calculation can be performed as follows. Drive method A: Black state transmittance 0.0067% x backlight brightness 10000cd / m 2 =0.67cd / m 2 Drive method B: Full white state transmittance 10% x backlight brightness 6.7cd / m 2 =0.67cd / m 2 That is, although the brightness of the display device is the same in driving method A and driving method B, driving method B consumes 1 / 1500th of the power consumption (standby power consumption).

[0128] In the second embodiment, the transmittance of the area of ​​front plate 110 that overlaps with the display area of ​​liquid crystal panel 100 is preferably 50% or more. That is, it is preferable that no smoke layer is disposed in the area of ​​front plate 110 that overlaps 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 panel 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 panel 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 achieved.

[0130] The refractive index of the optical contact layer 120 is preferably 1.4 or more and 1.6 or less. With the above configuration, it is possible to prevent the transmitted light that has passed through the design layer 111 from being reflected at the interface and returning to the viewer side, thereby achieving 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 internal reflectance. Except for the fact that circular polarizer 53 is provided on the front plate 110 side, this is the same as embodiment 1, and therefore 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 rear side. Examples of the circular polarizers 53 and 54 include a laminate of a λ / 4 wavelength plate and a linear polarizer. The circular polarizers 53 and 54 are preferably arranged so 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 perpendicular to each other.

[0133] The λ / 4 wave plate is not particularly limited as long as it imparts a ¼ phase difference to incident light of wavelength λ. The λ / 4 wave plate refers to a retardation plate that imparts an in-plane retardation of ¼ wavelength (strictly speaking, 137.5 nm) to light of wavelength 550 nm, for example, and preferably imparts an in-plane retardation of 120 nm or more and 150 nm or less.

[0134] The λ / 4 wave plate may have a fast axis and a slow axis perpendicular to the fast axis. The fast axis of the λ / 4 wave plate may be disposed so as to form an angle of substantially 45° with the transmission axis of the third linear polarizer. The angle of substantially 45° is preferably within a range of 45°±3°, more preferably within a range of 45°±1°, and even more preferably within a 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 performed effectively, so the display mode of the liquid crystal panel 100 is preferably a vertical electric field type such as VA mode rather than a horizontal electric field type such as IPS.

[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 embodiment 1, 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 embodiment 1, and the second electrode may be a counter electrode disposed to face the pixel electrode.

[0137] In a VA mode liquid crystal panel, it is preferable that the liquid crystal molecules contained in the liquid crystal layer 30 have negative dielectric anisotropy and are 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 referred to as backlight light) is not transmitted to the viewer side, and the liquid crystal panel 100 displays black. 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 tilt from the approximately vertical direction, allowing backlight light to transmit to the viewer side, and the liquid crystal panel displays white.

[0139] Also in the third embodiment, the transmittance of the area of ​​front substrate 110 that overlaps with the display area of ​​liquid crystal panel 100 is preferably 50% or more. Front substrate 110 and liquid crystal panel 100 are preferably bonded together by optical adhesion layer 120. Furthermore, the refractive index of optical adhesion 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 examined below using reference forms.

[0141] <Reference form 3> Reference form 3 differs from the configuration in Fig. 16 in that the liquid crystal panel and the front panel are not bonded together with an optical contact layer, and an air layer is provided between the liquid crystal panel and the front panel. The display method of the display device in reference form 3 will be described below 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> 16 in that the liquid crystal panel and the front panel are not bonded together with an optical contact layer, but rather there is an air layer between them, and that a smoke layer is disposed on the rear side of the design layer. The display method of the display device of Reference Form 4 will be described below by replacing the first linear polarizer 51 of the liquid crystal panel of Reference Form 2 shown in Figure 18 with a circular polarizer.

[0143] The configuration of 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 of 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 of 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 polarizer 52: Second linear polarizer 53, 54: Circular polarizer 100: LCD panel 110: Front plate 111: Design layer 112: Transparent material 113: Black frame layer 114: Flattening layer 120: Optical adhesive 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 device comprising a liquid crystal panel, a front panel disposed on a viewer 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 and the frame area in a plan view, the display device is switchable between a transmissive display that transmits at least a portion of the light incident from the liquid crystal panel and allows the viewer to view an arbitrary image displayed on the liquid crystal panel, and a reflective display that reflects at least a portion of the light incident from the viewer side and allows the viewer to view a pattern of the design layer, the backlight includes, in a plan view, a third region overlapping the display region of the liquid crystal panel and a fourth region overlapping the frame region of the liquid crystal panel; When the backlight is turned on, the luminance of the fourth region is 50% or less of the luminance of a central portion of the third region; the front panel includes, in a plan view, a first region overlapping the display region of the liquid crystal panel and a second region overlapping the frame region of the liquid crystal panel; A display device characterized in that the reflectance of the second region is 6% or more and 12% or less.

2. The backlight is a direct-type backlight in which a plurality of light-emitting elements are 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 light 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. 4. The display device according to claim 1, wherein the transmittance of the area of ​​the front panel that overlaps with the display area is 50% or more.

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

6. 6. The display device according to claim 5, wherein the optical contact layer has a refractive index of 1.4 or more and 1.6 or less.

7. A display device described in any one of claims 1 to 3, characterized in that the design layer contains a reflective pigment.

8. A display device described in any one of claims 1 to 3, characterized in that the reflectivity of the second region increases toward the first region.

Images