Indication device

Abstract

To provide a display device that can suppress a decline in display quality. [Solution] A display device according to one embodiment comprises a display panel having a first side surface and a first light source unit arranged along the first side surface. The display panel comprises a first transparent substrate having a first main surface, a second transparent substrate having a second main surface facing the first main surface, a liquid crystal layer disposed between the first transparent substrate and the second transparent substrate, a first electrode disposed between the liquid crystal layer and the first main surface, a second electrode disposed between the liquid crystal layer and the second main surface, and an inorganic insulating layer disposed between the second electrode and the liquid crystal layer and having a dielectric constant different from that of the liquid crystal layer. The thickness of the inorganic insulating layer decreases as the distance from the first light source unit increases.

Description

Technical Field

[0001] Embodiments of the present invention relate to a display device.

Background Art

[0002] In recent years, display devices having a polymer-dispersed liquid crystal layer (PDLC: Polymer Dispersed Liquid Crystal), a light source, etc. have been proposed. The polymer-dispersed liquid crystal layer can switch between a scattering state that scatters light and a transparent state that transmits light.

[0003] The display device can display an image in the scattering state. When the display panel is switched to the transparent state, the user can visually recognize the background through the display panel. An edge-lighting method in which a light source is arranged at an end of a light guide plate is adopted for a display device using PDLC. However, in the edge-lighting method, there is a problem that the luminance decreases as the distance from the light source increases.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] <M Therefore, one object of the present invention is to provide a display device capable of suppressing a decrease in display quality.

Means for Solving the Problems

[0006] A display device according to one embodiment has a liquid crystal layer containing polymer-dispersed liquid crystal, and is capable of switching between a state in which light incident on the liquid crystal layer is transmitted and a state in which light is scattered, depending on the applied voltage. The display device comprises a display panel having a first side surface and a first light source unit arranged along the first side surface. The display panel comprises a first transparent substrate having a first main surface, a second transparent substrate having a second main surface facing the first main surface, the liquid crystal layer disposed between the first transparent substrate and the second transparent substrate, a first electrode disposed between the liquid crystal layer and the first main surface, a second electrode disposed between the liquid crystal layer and the second main surface, and an inorganic insulating layer disposed between the second electrode and the liquid crystal layer and having a dielectric constant different from that of the liquid crystal layer. The thickness of the inorganic insulating layer decreases as the distance from the first light source unit increases.

[0007] A display device according to another embodiment includes a display panel having a first side surface and a second side surface, a first light source unit arranged along the first side surface, and a second light source unit arranged along the second side surface. The display panel includes a first transparent substrate having a first main surface, a second transparent substrate having a second main surface facing the first main surface, a liquid crystal layer disposed between the first transparent substrate and the second transparent substrate, a first electrode disposed between the liquid crystal layer and the first main surface, a second electrode disposed between the liquid crystal layer and the second main surface, and an inorganic insulating layer disposed between the second electrode and the liquid crystal layer. The inorganic insulating layer has the smallest thickness in the center of the display panel and increases in thickness as it approaches the first light source unit and the second light source unit from the center.

[0008] A display device according to yet another embodiment includes a plurality of pixels, a display panel having a first side surface, and a first light source unit arranged along the first side surface. The display panel includes a first transparent substrate having a first main surface, a second transparent substrate having a second main surface facing the first main surface, a liquid crystal layer disposed between the first transparent substrate and the second transparent substrate, an electrode disposed between the liquid crystal layer and the second main surface, and an inorganic insulating layer disposed between the electrode and the liquid crystal layer, overlapping with the plurality of pixels, and having a dielectric constant smaller than that of the liquid crystal layer. The thickness of the inorganic insulating layer decreases as the distance from the first light source unit increases. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows an example of the configuration of a display device according to the first embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing an example of the configuration of the display panel shown in Figure 1. [Figure 3] Figure 3 is a schematic cross-sectional view of the display device according to the first embodiment. [Figure 4] Figure 4 is a schematic plan view of the display device according to the first embodiment. [Figure 5] Figure 5 is a schematic enlarged view of section V shown in Figures 3 and 4. [Figure 6] Figure 6 is a schematic enlarged view of section VI shown in Figures 3 and 4. [Figure 7] Figure 7 is a schematic cross-sectional view of the display device according to the second embodiment. [Figure 8] Figure 8 is a schematic enlarged view of section VIII shown in Figure 7. [Figure 9] Figure 9 is a schematic enlarged view of section IX shown in Figure 7. [Figure 10] Figure 10 is a schematic plan view of the display device according to the third embodiment. [Figure 11] Figure 11 is a schematic cross-sectional view of the display device according to the third embodiment. [Figure 12]Figure 12 is a schematic enlarged view of section XII shown in Figures 10 and 11. [Figure 13] Figure 13 is a schematic enlarged view of section XIII shown in Figures 10 and 11. [Figure 14] Figure 14 is a schematic enlarged view of section XIV shown in Figures 10 and 11. [Figure 15] Figure 15 is a schematic cross-sectional view of the display device according to the fourth embodiment. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the drawings. Note that the disclosure is merely an example, and modifications that can be easily conceived by those skilled in the art while maintaining the spirit of the invention are naturally included within the scope of the present invention. Furthermore, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the actual embodiment in order to clarify the explanation; however, these are merely examples and do not limit the interpretation of the present invention. In this specification and in each drawing, components that perform the same or similar functions as those described above in previously shown drawings are given the same reference numerals, and redundant detailed explanations may be omitted as appropriate. The drawings will include mutually orthogonal X, Y, and Z axes as needed to facilitate understanding. The direction along the X axis will be referred to as the first direction X, the direction along the Y axis as the second direction Y, and the direction along the Z axis as the third direction Z. Viewing the various elements parallel to the third direction Z is called a plan view.

[0011] In each embodiment, a highly translucent liquid crystal display device (a so-called transparent display device) using polymer-dispersed liquid crystal is disclosed as an example of a display device. However, the configuration disclosed in this embodiment can also be applied to other types of display devices.

[0012] [First Embodiment] FIG. 1 is a diagram showing a configuration example of a display device DSP according to the present embodiment. The display device DSP includes a display panel PNL, a light source unit LU1 (first light source unit), and a light guide LG. In the example shown in FIG. 1, the light source unit LU1 and the light guide LG are marked with broken lines to omit a part thereof.

[0013] In the example shown in FIG. 1, the shape of the display panel PNL in plan view is a rectangular shape elongated in the second direction Y. However, the shape of the display panel PNL is not limited to this example, and may be, for example, a rectangular shape elongated in the second direction Y, a square shape, a circular shape, an elliptical shape, or the like. The display panel PNL includes a first substrate SUB1 and a second substrate SUB2 stacked in the third direction Z.

[0014] The length of the first substrate SUB1 in the second direction Y is larger than the length of the second substrate SUB2 in the second direction Y. The first substrate SUB1 has a mounting region MA formed in a portion protruding in the direction opposite to the second direction Y from the second substrate SUB2. The mounting region MA corresponds to a region of the first substrate SUB1 that does not overlap the second substrate SUB2. An integrated circuit or a flexible circuit board (not shown) is mounted in the mounting region MA.

[0015] The display panel PNL has a display region DA for displaying an image and a frame-shaped peripheral region SA surrounding the display region DA. Both the display region DA and the peripheral region SA are formed in a portion where the first substrate SUB1 and the second substrate SUB2 overlap. The display region DA includes a plurality of pixels PX arranged in a matrix in the first direction X and the second direction Y.

[0016] The display panel PNL further includes a liquid crystal layer LC sealed between the first substrate SUB1 and the second substrate SUB2. As schematically shown enlarged below FIG. 1, the liquid crystal layer LC is composed of a polymer dispersed liquid crystal containing a polymer 31 and liquid crystal molecules 32.

[0017] In one example, polymer 31 is a liquid crystalline polymer. Polymer 31 is formed in streaks extending along a first direction X and aligned in a second direction Y. Liquid crystal molecules 32 are dispersed in the gaps of polymer 31 and oriented so that their long axes are aligned along the first direction X.

[0018] Each of the polymer 31 and the liquid crystal molecules 32 possesses optical anisotropy or refractive index anisotropy. The responsiveness of polymer 31 to an electric field is lower than that of liquid crystal molecules 32. In one example, the orientation direction of polymer 31 hardly changes regardless of the presence or absence of an electric field. In contrast, the orientation direction of liquid crystal molecules 32 changes in response to the voltage applied to the liquid crystal layer LC.

[0019] When no voltage is applied to the liquid crystal layer LC, the optical axes of the polymer 31 and the liquid crystal molecules 32 are parallel to each other, and light incident on the liquid crystal layer LC is transmitted through with almost no scattering (transparent state).

[0020] When a voltage is applied to the liquid crystal layer LC, the optical axes of the polymer 31 and the liquid crystal molecules 32 intersect with each other, and the light incident on the liquid crystal layer LC is scattered within the liquid crystal layer LC (scattering state). In other words, the display device DSP can switch between a transparent state and a scattering state depending on the applied voltage.

[0021] As shown in the enlarged view above Figure 1, the display area DA contains multiple scan lines G and multiple signal lines S. The multiple scan lines G extend in the first direction X and are spaced apart in the second direction Y. The multiple signal lines S extend in the second direction Y and are spaced apart in the first direction X. The multiple signal lines S intersect with the multiple scan lines G.

[0022] Each pixel PX comprises a switching element SW, a pixel electrode PE, a common electrode CE, and a capacitor CS. The switching element SW is composed of, for example, a thin-film transistor (TFT) and is electrically connected to the scan line G and the signal line S. The pixel electrode PE is electrically connected to the switching element SW.

[0023] The liquid crystal layer LC (particularly the liquid crystal molecules 32) is driven by the electric field generated between the pixel electrode PE and the common electrode CE. A capacitance CS is formed, for example, between an electrode at the same potential as the common electrode CE and an electrode at the same potential as the pixel electrode PE.

[0024] The light source unit LU1 and the light guide LG are arranged along the mounting area MA. The light source unit LU1 has multiple light-emitting elements LS aligned in the first direction X. Each light-emitting element LS illuminates the light guide LG. As the light guide LG, a lens such as a prism lens can be used.

[0025] For example, a plurality of light-emitting elements LS may include a light-emitting element that emits red light, a light-emitting element that emits green light, and a light-emitting element that emits blue light. These light-emitting elements may be arranged in a first direction X, or they may be stacked in a third direction Z. LEDs (Light Emitting Diodes) can be used as the light-emitting elements LS.

[0026] Figure 2 is a schematic cross-sectional view showing an example configuration of the display panel PNL shown in Figure 1. The first substrate SUB1 comprises a first transparent substrate 10, insulating films 11 and 12, a capacitive electrode 13, a switching element SW, a pixel electrode PE (first electrode), and an alignment film AL1 (first alignment film).

[0027] Although not shown in the diagram, the first substrate SUB1 further includes the scan lines G and signal lines S shown in Figure 1. The switching element SW is located on the main surface 10B (first main surface) of the first transparent substrate 10. The main surface 10B is the surface facing the second transparent substrate 20. The insulating film 11 covers the switching element SW. The capacitive electrode 13 is located between the insulating film 11 and the insulating film 12.

[0028] In the illustrated example, the insulating film 11 and the capacitive electrode 13 are arranged across the entire surface of each pixel PX, but the example is not limited to this. The insulating film 11 only needs to be arranged to cover at least the switching element SW, the scan line G, and the signal line S.

[0029] The capacitive electrodes 13 may be formed in a grid pattern along the scan lines G and signal lines S. Pixel electrodes PE are arranged on the insulating film 12 for each pixel PX. The pixel electrodes PE are electrically connected to the switching element SW via the aperture OP of the capacitive electrodes 13.

[0030] The pixel electrode PE overlaps the capacitive electrode 13 with the insulating film 12 in between, forming the capacitance CS of the pixel PX. The alignment film AL1 is positioned between the liquid crystal layer and the pixel electrode PE, covering the pixel electrode PE.

[0031] The second substrate SUB2 comprises a second transparent substrate 20, a light-shielding layer BM, a common electrode CE (second electrode), an inorganic insulating layer 21, and an alignment film AL2 (second alignment film). The second transparent substrate 20 faces the first transparent substrate 10 in the third direction Z.

[0032] The light-shielding layer BM and the common electrode CE are located on the main surface 20A (second main surface) of the second transparent substrate 20. The main surface 20A is the surface facing the main surface 10B of the first transparent substrate 10. The light-shielding layer BM is located, for example, directly above the switching element SW and directly above the scan line G and signal line S (not shown).

[0033] The common electrode CE faces the pixel electrode PE in the third direction Z, with the liquid crystal layer LC in between. The common electrode CE is arranged across multiple pixels PX and directly covers the light-shielding layer BM. The common electrode CE is electrically connected to the capacitive electrode 13 and is at the same potential as the capacitive electrode 13.

[0034] In the example shown in Figure 2, the inorganic insulating layer 21 is positioned between the common electrode CE and the liquid crystal layer LC. Specifically, the inorganic insulating layer 21 is positioned between the common electrode CE and the alignment film AL2. The inorganic insulating layer 21 overlaps multiple pixel electrodes PE.

[0035] The dielectric constant of the inorganic insulating layer 21 is different from that of the liquid crystal layer LC. For example, the dielectric constant of the inorganic insulating layer 21 is smaller than that of the liquid crystal layer LC. Specifically, the dielectric constant of the inorganic insulating layer 21 is approximately 7 F / m, while the dielectric constant of the liquid crystal layer LC is approximately 20 F / m.

[0036] Furthermore, since the inorganic insulating layer 21 covers the common electrode CE, it functions as a protective layer to suppress peeling of the common electrode CE. The structure of the inorganic insulating layer 21 will be explained in Figure 3 and subsequent figures.

[0037] The alignment film AL2 is positioned between the liquid crystal layer LC and the inorganic insulating layer 21, and covers the inorganic insulating layer 21. In other words, the alignment film AL2 is in contact with the inorganic insulating layer 21. The liquid crystal layer LC is positioned between the first transparent substrate 10 and the second transparent substrate 20, and is in contact with the alignment films AL1 and AL2.

[0038] In the first substrate SUB1, the insulating film 11, insulating film 12, capacitive electrode 13, switching element SW, pixel electrode PE, alignment film AL1, scan line G, and signal line S are located between the first transparent substrate 10 and the liquid crystal layer LC. In the second substrate SUB2, the light-shielding layer BM, common electrode CE, inorganic insulating layer 21, and alignment film AL2 are located between the second transparent substrate 20 and the liquid crystal layer LC.

[0039] The first transparent substrate 10 and the second transparent substrate 20 are insulating substrates such as glass substrates and plastic substrates. The insulating film 11 is formed from a transparent insulating material such as silicon oxide, silicon nitride, silicon oxynitride, or acrylic resin.

[0040] In one example, the insulating film 11 includes an inorganic insulating film and an organic insulating film. The insulating film 12 is an inorganic insulating film such as silicon nitride. The capacitive electrode 13, the pixel electrode PE, and the common electrode CE are transparent electrodes formed from transparent conductive materials such as indium tin oxide (ITO) and indium zinc oxide (IZO). The light-shielding layer BM is, for example, a conductive layer with lower resistance than the common electrode CE.

[0041] In one example, the light-shielding layer BM is formed from an opaque metallic material such as molybdenum, aluminum, tungsten, titanium, or silver. The alignment films AL1 and AL2 are horizontal alignment films having an alignment restricting force substantially parallel to the XY plane. In one example, the alignment films AL1 and AL2 are oriented along the second direction Y. The alignment treatment may be a rubbing treatment or a photo-alignment treatment.

[0042] Figure 3 is a schematic cross-sectional view of the display device DSP according to this embodiment. Figure 4 is a schematic plan view of the display device DSP according to this embodiment. In Figure 3, the structure of the display panel PNL and the like are schematically shown, and elements such as scan lines G, signal lines S, and switching elements SW are omitted.

[0043] In Figure 4, arrow A1 indicates the direction of light propagation emitted by the light-emitting element LS of the light source unit LU1. The emission surface of the light-emitting element LS faces the second direction Y. In other words, the normal direction of this emission surface is parallel to the second direction Y.

[0044] As shown in Figure 3, the first substrate SUB1 is bonded to the second substrate SUB2 by a sealing material SE. The sealing material SE has a shape that surrounds the display area DA in a plan view. The liquid crystal layer LC is sealed within the space surrounded by the sealing material SE.

[0045] The first substrate SUB1 is equipped with the pixel electrode PE described above. The second substrate SUB2 is equipped with the common electrode CE described above. The pixel electrode PE and the common electrode CE face each other via a liquid crystal layer LC.

[0046] The first transparent substrate 10 has a main surface F1, a main surface F2 opposite to main surface F1, and side surfaces E1a and E1b connecting main surface F1 and main surface F2. The second transparent substrate 20 has a main surface F3, a main surface F4 opposite to main surface F3, and side surfaces E2a and E2b connecting main surface F3 and main surface F4. Main surface F3 faces main surface F2 via a liquid crystal layer LC.

[0047] In this embodiment, side E2a corresponds to the first side of the display panel PNL, and side E2b corresponds to the second side. The light source unit LU1 and the light guide LG are arranged along side E2a.

[0048] The display device DSP further includes a cover member CM1 superimposed on the display panel PNL. The cover member CM1 is transparent and, in one example, is a cover glass made of glass.

[0049] The cover member CM1 may be formed from a transparent resin material such as plastic. The thickness of the cover member CM1 is sufficiently greater than the thickness of the first substrate SUB1 and the second substrate SUB2. Here, thickness is the distance along the third direction Z.

[0050] The cover member CM1 has a main surface F5 facing the main surface F4, a main surface F6 on the opposite side of main surface F5, and side surfaces E3a and E3b connecting main surfaces F5 and F6. Main surface F5 is bonded to main surface F4 by a transparent adhesive layer AD1. The adhesive layer AD1 is formed by, for example, OCA (Optical Clear Adhensive) or OCR (Optical Clear Resin).

[0051] Sides E1a, E2a, and E3a are all located on the light-emitting element LS side (light-receiving side). Sides E1b, E2b, and E3b are all located on the opposite side of the light-emitting element LS (anti-light-receiving side). The mounting area MA is formed on the portion of the first substrate SUB1 that protrudes beyond side E2a.

[0052] The display panel PNL may further include a reflective material RF. The reflective material RF is located near the sides E1b, E2b, and E3b. In other words, in the second direction Y, the reflective material RF is located on the opposite side of the light source unit LU1, with the cover member CM1 in between. The reflective material RF is, for example, a reflective tape attached to the sides E1b, E2b, and E3b.

[0053] The light-emitting element LS faces side E3a, with the light guide LG in between. Figure 2 shows an example of the path of light L emitted by the light-emitting element LS. The light-emitting element LS emits light along the second direction Y. Specifically, the light-emitting element LS emits light toward side E3a. The light L emitted from the light-emitting element LS passes through the light guide LG and enters side E3a.

[0054] This light L moves towards the incoming light side while undergoing repeated total internal reflection between the main surfaces F1 and F6. The light L that reaches the sides E1b, E2b, and E3b is reflected by the reflective material RF and moves towards the incoming light side while undergoing repeated total internal reflection between the main surfaces F1 and F6.

[0055] In the vicinity of a transparent pixel PX, light L is hardly scattered by the liquid crystal layer LC. Therefore, light L hardly leaks out of the first substrate SUB1 and the cover member CM1.

[0056] On the other hand, near a pixel PX in a scattered state, light L is scattered by the liquid crystal layer LC. This scattered light SL is emitted from the first substrate SUB1 and the cover member CM1 and is visible to the user as a displayed image. By gradually defining the voltage applied to the pixel electrode PE within a predetermined range, it is also possible to achieve gradation in the degree of scattering (brightness).

[0057] Furthermore, in the vicinity of the transparent pixels PX, ambient light incident on the first substrate SUB1 and the cover member CM1 is transmitted through the liquid crystal layer LC with almost no scattering. That is, when viewing the display device DSP from the first substrate SUB1 side, the background on the cover member CM1 side is visible, and when viewing the display device DSP from the cover member CM1 side, the background on the cover member CM1 side is visible.

[0058] For example, a field sequential method can be used as the image display method by the display device DSP, which repeatedly displays a red image by lighting up a red light-emitting element among multiple light-emitting elements LS, a green image by lighting up a green light-emitting element, and a blue image by lighting up a blue light-emitting element.

[0059] Next, we will explain the inorganic insulating layer 21 provided on the second substrate SUB2.

[0060] As shown in Figure 3, the inorganic insulating layer 21 has a thickness that decreases as you move in the second direction Y, when viewed in the direction opposite to the first direction X. In this embodiment, the second direction Y corresponds to the direction away from the light source unit LU1. As you move in the second direction Y, the distance from the light source unit LU1 increases.

[0061] The inorganic insulating layer 21 is formed, for example, in a stepped manner. In other words, the inorganic insulating layer 21 decreases in thickness in stages. The main surface F7 of the inorganic insulating layer 21 facing the liquid crystal layer LC approaches the common electrode CE as it progresses in the second direction Y. The inorganic insulating layer 21 has multiple portions in which the thickness gradually decreases in the second direction Y. In one example, these portions are formed in 10 steps, but are not limited to this example.

[0062] Here, with reference to FIGS. 5 and 6, among the plurality of portions, the portion located on the light incident side and the portion located on the anti-light incident side will be described. FIG. 5 is a schematic enlarged view of the V portion shown in FIGS. 3 and 4. FIG. 6 is a schematic enlarged view of the VI portion shown in FIGS. 3 and 4. In FIGS. 5 and 6, the cover member CM1 and the like are omitted.

[0063] As shown in FIGS. 5 and 6, the inorganic insulating layer 21 has a portion P1 (first portion) and a portion P2 (second portion). The portion P1 is disposed at a position closest to the light source unit LU1. The portion P2 is located at a position spaced apart from the light source unit LU1 more than the portion P1 and is disposed at a position most spaced apart from the light source unit LU1. The distance from the light source unit LU1 to the portion P2 is greater than the distance from the light source unit LU1 to the portion P1.

[0064] As shown in FIG. 3, the inorganic insulating layer 21 includes a plurality of portions having different thicknesses between the portion P1 and the portion P2. The thicknesses of the plurality of portions gradually decrease in the second direction Y.

[0065] As shown in FIG. 5, the portion P1 has a thickness T1 (first thickness). As shown in FIG. 6, the portion P2 has a thickness T2 (second thickness). The thickness T2 is smaller than the thickness T1 (T2 < T1). The thickness T1 corresponds to the maximum thickness in the inorganic insulating layer 21, and the thickness T2 corresponds to the minimum thickness in the inorganic insulating layer 21.

[0066] The thicknesses T1 and T2 of the portion P1 and the portion P2 are constant in the first direction X. In other words, the inorganic insulating layer 21 changes in thickness depending on the position in the Y-Z plane defined by the second direction Y and the third direction Z, but does not change in thickness in the X-Z plane defined by the first direction X and the third direction Z.

[0067] The thickness T1 of part P1 is, for example, less than half the distance between the pixel electrode PE and the common electrode CE. The thickness T1 of part P1 is, for example, less than one-third of the distance between the pixel electrode PE and the common electrode CE. The distance between the pixel electrode PE and the common electrode CE is, for example, 3 μm. The thickness T1 of part P1 is 1 μm or less, for example, 1 μm.

[0068] Furthermore, when the inorganic insulating layer 21 is formed in a stepped shape, the difference in thickness between adjacent portions in the second direction Y is preferably 0.7 μm or less. In one example, the difference in thickness between adjacent portions in the second direction Y is 0.1 μm, but the difference may be greater than or less than 0.1 μm. By reducing the difference in thickness (step) between adjacent portions in the second direction Y, the impact on image display and appearance can be suppressed.

[0069] Focusing on the orientation film AL2 covering the inorganic insulating layer 21, the orientation film AL2 has a substantially constant thickness in the second direction Y. Therefore, the orientation film AL2 is also formed in a stepped shape, as shown in Figure 3.

[0070] Focusing on the pixel electrode PE and the common electrode CE, the distance between the pixel electrode PE and the common electrode CE is approximately constant in the second direction Y, as shown in Figure 3. Therefore, the liquid crystal layer LC has a thickness that increases as it progresses in the second direction Y.

[0071] As shown in Figures 5 and 6, the liquid crystal layer LC has a liquid crystal portion LC1 (first liquid crystal portion) that overlaps with portion P1 and a liquid crystal portion LC2 (second liquid crystal portion) that overlaps with portion P2. Liquid crystal portion LC1 is positioned closest to the light source unit LU1, and liquid crystal portion LC2 is positioned furthest from the light source unit LU1.

[0072] Liquid crystal layer LC1 has a thickness T3 (third thickness). Liquid crystal layer LC2 has a thickness T4 (fourth thickness). Thickness T4 is greater than thickness T3 (T4 > T3). Also, the sum of thicknesses T1 and T3 is substantially equal to the sum of thicknesses T2 and T4. Focusing on the volume of the liquid crystal layers LC, the volume of liquid crystal layer LC2 is greater than the volume of liquid crystal layer LC1.

[0073] The light emitted from the light source unit LU1 decreases as it moves away from the light source unit LU1, due to absorption and scattering by the wiring, light shielding layer BM, and various insulating films.

[0074] When significant light scattering occurs on the incoming side, it becomes difficult for light to reach the incoming side. Specifically, the brightness on the incoming side increases, while the brightness on the incoming side decreases. This results in uneven brightness in the second direction Y. This can lead to a decrease in display quality.

[0075] As described above, the distance between the pixel electrode PE and the common electrode CE is approximately constant in the second direction Y, therefore the voltage Vc applied between the pixel electrode PE and the common electrode CE is approximately constant in the second direction Y.

[0076] An inorganic insulating layer 21, made of a material with a different dielectric constant than the liquid crystal layer LC, is placed between the liquid crystal layer LC and the common electrode CE. As a result, a voltage is also applied to the inorganic insulating layer 21. In other words, by placing the inorganic insulating layer 21, the voltage Vc is divided, and the voltage applied to the liquid crystal layer LC (effective voltage) can be reduced.

[0077] Furthermore, the inorganic insulating layer 21 has a thickness that decreases as it progresses in the second direction Y. As the thickness of the inorganic insulating layer 21 decreases, the voltage applied to the inorganic insulating layer 21 decreases, while the voltage applied to the liquid crystal layer LC increases. In other words, the effective voltage increases as it progresses in the second direction Y.

[0078] As shown in the examples of FIGS. 5 and 6, a voltage V1 is applied to the portion P1 of the inorganic insulating layer 21, and a voltage V2 is applied to the portion P2 of the inorganic insulating layer 21. The voltage V1 is greater than the voltage V2 (V1 > V2).

[0079] Focusing on the liquid crystal layer LC, a voltage VL1 is applied to the liquid crystal portion LC1, and a voltage VL2 is applied to the liquid crystal portion LC2. The voltage VL1 is smaller than the voltage VL2 (VL1 < VL2). That is, a larger voltage is applied to the liquid crystal portion LC2 located on the anti-incident light side than to the liquid crystal portion LC1 located on the incident light side.

[0080] When the driving voltage increases, the light scattering intensity of the liquid crystal layer LC increases. That is, the light scattering intensity of the liquid crystal layer LC increases as it moves away from the light source unit LU1. Since the luminance due to scattering decreases when the scattering intensity decreases, the luminance on the incident light side can be suppressed and the luminance on the anti-incident light side can be improved. Thereby, the uniformity of luminance in the second direction Y can be improved. As a result, a decrease in display quality can be suppressed.

[0081] Furthermore, focusing on the liquid crystal layer LC, the liquid crystal layer LC has an increasing thickness as it progresses in the second direction Y. When the thickness of the liquid crystal layer LC (the volume of the liquid crystal layer LC) increases, the liquid crystal layer LC becomes more likely to scatter light. In the present embodiment, not only the voltage applied to the liquid crystal layer LC but also the scattering intensity is adjusted by the thickness of the liquid crystal layer LC.

[0082] Specifically, in the liquid crystal layer LC, the scattering intensity is adjusted to be small on the incident light side and large on the anti-incident light side. Thereby, a decrease in luminance from the incident light side to the anti-incident light side can be further suppressed. As a result, a decrease in the display quality of the display device DSP can be suppressed.

[0083] With the display device DSP configured as described above, a decrease in display quality can be suppressed. In addition, various favorable effects can be obtained from the present embodiment.

[0084] In this embodiment, an example is disclosed in which the inorganic insulating layer 21 is arranged on the second substrate SUB2. However, the inorganic insulating layer 21 may be formed on the first substrate SUB1, or on both the first substrate SUB1 and the second substrate SUB2. Furthermore, the rate at which the thickness of the liquid crystal layer LC changes from the light-receiving side to the light-rejecting side can be changed as appropriate. In addition, the inorganic insulating layer 21 does not have to be arranged in the region furthest from the light source unit LU1.

[0085] Next, other embodiments will be described. In the other embodiments described below, components similar to those in the first embodiment described above will be given the same reference numerals as in the first embodiment, and their detailed descriptions may be omitted or simplified.

[0086] [Second Embodiment] Figure 7 is a schematic cross-sectional view of the display device DSP according to this embodiment. Figure 8 is a schematic enlarged view of section VIII shown in Figure 7. Figure 9 is a schematic enlarged view of section IX shown in Figure 7. In this embodiment, the thickness of the liquid crystal layer LC differs from that of the first embodiment.

[0087] The second substrate SUB2 further comprises an organic insulating layer 22, as shown in Figure 7. The organic insulating layer 22 is formed of an organic insulating material such as polyimide or polyamide. The dielectric constant of the organic insulating layer 22 is different from that of the liquid crystal layer LC and the inorganic insulating layer 21, respectively. The dielectric constant of the organic insulating layer 22 is, for example, smaller than that of the liquid crystal layer LC and the inorganic insulating layer 21. Specifically, the dielectric constant of the organic insulating layer 22 is, for example, about 3 F / m.

[0088] In the example shown in Figure 7, the organic insulating layer 22 is positioned between the common electrode CE and the liquid crystal layer LC. Specifically, the organic insulating layer 22 is positioned between the common electrode CE and the inorganic insulating layer 21. Alternatively, the organic insulating layer 22 may be positioned between the inorganic insulating layer 21 and the alignment film AL2.

[0089] As shown in Figure 7, the organic insulating layer 22 has a thickness that increases as you move in the second direction Y, when viewed in the direction opposite to the first direction X. The organic insulating layer 22 is formed, for example, in a stepped shape.

[0090] In other words, the main surface F8 of the organic insulating layer 22 facing the liquid crystal layer LC moves away from the common electrode CE as the second direction Y progresses. In contrast, the main surface F7 of the inorganic insulating layer 21 is parallel to the XY plane defined by the first direction X and the second direction Y. Focusing on the liquid crystal layer LC, the thickness of the liquid crystal layer is approximately constant in the second direction Y.

[0091] The inorganic insulating layer 21 has multiple portions whose thickness gradually decreases in the second direction Y. The inorganic insulating layer 21 has portion P1 and portion P2, as shown in Figures 8 and 9.

[0092] In the example shown in Figure 8, the organic insulating layer 22 is not positioned to overlap with portion P1. Portion P1 is in contact with the common electrode CE. The organic insulating layer 22 is positioned to overlap with a portion of the inorganic insulating layer 21 that has a thickness less than the maximum thickness of the inorganic insulating layer 21. Focusing on the thickness of the organic insulating layer 22, as shown in Figure 9, the organic insulating layer 22 has its maximum thickness at the position where it overlaps with portion P2.

[0093] The organic insulating layer 22 has varying thickness depending on its position in the YZ plane, but its thickness remains constant in the XZ plane. Focusing on the alignment film AL2, the alignment film AL2 is approximately parallel to the XY plane, as shown in Figure 7.

[0094] In this embodiment, an organic insulating layer 22, made of a material having a different dielectric constant than the liquid crystal layer LC and the inorganic insulating layer 21, is placed between the common electrode CE and the liquid crystal layer LC. Therefore, a voltage is also applied to the organic insulating layer 22.

[0095] Therefore, when the thickness of the liquid crystal layer LC is constant, the voltage (execution voltage) applied to the liquid crystal layer LC can be reduced according to the thicknesses of the inorganic insulating layer 21 and the organic insulating layer 22 overlapping the liquid crystal layer LC.

[0096] Assuming that a voltage Vc is applied between the pixel electrode PE and the common electrode CE, as in the examples shown in FIGS. 8 and 9, a voltage V1 is applied to the portion P1 of the inorganic insulating layer 21, a voltage V2 is applied to the portion P2 of the inorganic insulating layer 21, and a voltage V3 is applied to the organic insulating layer 22. The voltage V1 is greater than the sum of the voltage V2 and the voltage V3 (V1 > (V2 + V3)).

[0097] Focusing on the liquid crystal layer LC, a voltage VL1 is applied to the liquid crystal portion LC1, and a voltage VL2 is applied to the liquid crystal portion LC2. The voltage VL1 is smaller than the voltage VL2 (VL1 < VL2). That is, a larger voltage is applied to the liquid crystal portion LC2 located on the anti-incident light side than to the liquid crystal portion LC1 located on the incident light side.

[0098] By arranging the inorganic insulating layer 21 and the organic insulating layer 22 having the above-described shape, the execution voltage increases as it progresses in the second direction Y. That is, in the present embodiment, the light scattering intensity of the liquid crystal layer LC increases as it moves away from the light source unit LU1.

[0099] Thereby, by suppressing the luminance on the incident light side and improving the luminance on the anti-incident light side, the luminance uniformity in the second direction Y can be improved. As a result, a decrease in display quality can be suppressed.

[0100] In the present embodiment as well, the same effects as those of the first embodiment can be obtained. In the present embodiment, since the thickness of the liquid crystal layer LC is constant, it becomes easier to stabilize the quality of the display device DSP.

[0101] In this embodiment, an example is disclosed in which the organic insulating layer 22 is not located in the position closest to the light source unit LU1. However, the organic insulating layer 22 may be located in the position closest to the light source unit LU1.

[0102] [Third Embodiment] Figure 10 is a schematic plan view of the display device DSP according to this embodiment. Figure 11 is a schematic cross-sectional view of the display device DSP according to this embodiment. This embodiment differs from the first embodiment in that the display device DSP further comprises a light source unit LU2 (second light source unit).

[0103] As shown in Figure 11, the light source unit LU2 is arranged along the sides E1b, E2b, and E3b. In Figure 10, the direction of light propagation emitted by the light-emitting element LS of the light source unit LU2 is indicated by arrow A2.

[0104] Focusing on the inorganic insulating layer 21, as shown in Figure 11, the inorganic insulating layer 21 has a thickness that is smallest in the center of the display panel PNL (display area DA) in the second direction Y, and increases as it approaches the light source units LU1 and LU2 from the center.

[0105] The inorganic insulating layer 21 is formed, for example, in a stepped shape. Specifically, the inorganic insulating layer 21 has multiple portions in which the thickness gradually decreases from the side surfaces E2a and E2b toward the center.

[0106] Here, using Figures 12 to 14, we will explain the parts located on the light source units LU1 and LU2 side, and the part located in the central area.

[0107] Figure 12 is a schematic enlarged view of section XII shown in Figures 10 and 11. Figure 13 is a schematic enlarged view of section XIII shown in Figures 10 and 11. Figure 14 is a schematic enlarged view of section XIV shown in Figures 10 and 11.

[0108] As shown in FIGS. 12 to 14, the inorganic insulating layer 21 has a portion P1, a portion P2, and a portion P3. In the present embodiment, the portion P1 corresponds to the first portion, the portion P2 corresponds to the second portion, and the portion P3 corresponds to the third portion.

[0109] Note that as shown in FIG. 11, the inorganic insulating layer 21 includes a plurality of portions having different thicknesses between the portion P1 and the portion P2 and between the portion P2 and the portion P3. The light source unit LU1, the portion P1, the portion P2, the portion P3, and the light source unit LU2 are arranged in this order in the second direction Y. The portion P3 is configured in the same manner as the portion P1.

[0110] As shown in FIG. 12, the portion P1 has a thickness T1. As shown in FIG. 13, the portion P2 has a thickness T2. As shown in FIG. 14, the portion P3 has a thickness T5. In the present embodiment, the thickness T1 of the portion P1 corresponds to the first thickness, the thickness of the portion P2 corresponds to the second thickness, and the thickness T5 of the portion P3 corresponds to the fifth thickness.

[0111] The thickness T1 of the portion P1 is substantially equal to the thickness T5 of the portion P3. Also, the thickness T2 of the portion P2 is smaller than the thicknesses T1 and T5 (T2 < T1 = T5). In the inorganic insulating layer 21, the thicknesses T1 and T5 correspond to the maximum thickness, and the thickness T2 corresponds to the minimum thickness.

[0112] The thicknesses T1, T2, and T5 in the portion P1, the portion P2, and the portion P3 are constant in the first direction X. In other words, the inorganic insulating layer 21 changes in thickness depending on the position in the Y-Z plane, but does not change in thickness in the X-Z plane.

[0113] Focusing on the alignment film AL2 covering the inorganic insulating layer 21, the alignment film AL2 has a substantially constant thickness in the second direction Y. Therefore, the alignment film AL2 is also formed in a stepped shape as shown in FIG. 11.

[0114] As shown in FIGS. 12 to 14, the liquid crystal layer LC has a liquid crystal portion LC1 overlapping the portion P1, a liquid crystal portion LC2 overlapping the portion P2, and a liquid crystal portion LC3 overlapping the portion P3. In the present embodiment, the liquid crystal portion LC1 corresponds to the first liquid crystal portion, the liquid crystal portion LC2 overlapping the portion P2 corresponds to the second liquid crystal portion, and the liquid crystal portion LC3 overlapping the portion P3 corresponds to the third liquid crystal portion.

[0115] The liquid crystal portion LC1 has a thickness T3. The liquid crystal portion LC2 has a thickness T4. The liquid crystal portion LC3 has a thickness T6. The thickness T3 of the liquid crystal portion LC1 corresponds to the third thickness, the thickness T4 of the liquid crystal portion LC2 corresponds to the fourth thickness, and the thickness T6 of the liquid crystal portion LC3 corresponds to the sixth thickness.

[0116] The thickness T3 of the liquid crystal portion LC1 is substantially equal to the thickness T6 of the liquid crystal portion LC3. The thickness T4 of the liquid crystal portion LC2 is greater than the thicknesses T3 and T6 (T4>T3=T6). Focusing on the volume of the liquid crystal layer LC, the volume of the liquid crystal portion LC2 is greater than the volumes of the liquid crystal portions LC1 and LC3.

[0117] Assuming that a voltage Vc is applied between the pixel electrode PE and the common electrode CE, as in the example shown in FIGS. 12 to 14, a voltage V1 is applied to the portion P1 of the inorganic insulating layer 21, a voltage V2 is applied to the portion P2 of the inorganic insulating layer 21, and a voltage V3 is applied to the portion P3 of the inorganic insulating layer 21. The voltage V1 is substantially equal to the voltage V3, and the voltages V1 and V3 are greater than the voltage V2 (V1=V3>V2).

[0118] Focusing on the liquid crystal layer LC, a voltage VL1 is applied to the liquid crystal portion LC1, a voltage VL2 is applied to the liquid crystal portion LC2, and a voltage VL3 is applied to the liquid crystal portion LC3. The voltage VL1 is substantially equal to the voltage VL3, and the voltages VL1 and VL3 are smaller than the voltage VL2 (VL1=VL3<VL2). That is, a larger voltage is applied to the liquid crystal portion LC2 located in the central portion than to the liquid crystal portions LC1 and LC3 located on the light incident side.

[0119] In this embodiment as well, the same effects as in the first embodiment can be obtained. In this embodiment, when the display device DSP further includes a light source unit LU2, light scattering at positions close to the light source units LU1 and LU2 can be suppressed, and light can be delivered to the center of the display area DA in the second direction Y. As a result, the uniformity of brightness is improved, and a decrease in display quality can be suppressed.

[0120] [Fourth Embodiment] Figure 15 is a schematic cross-sectional view of the display device DSP according to this embodiment. This embodiment differs from the second embodiment in that the display device DSP further comprises a light source unit LU2 (second light source unit).

[0121] The second substrate SUB2 further comprises an organic insulating layer 22, as shown in Figure 15. In the example shown in Figure 15, the organic insulating layer 22 is located between the common electrode CE and the liquid crystal layer LC. Specifically, the organic insulating layer 22 is located between the common electrode CE and the inorganic insulating layer 21. Alternatively, the organic insulating layer 22 may be located between the inorganic insulating layer 21 and the alignment film AL2.

[0122] As shown in Figure 15, the organic insulating layer 22 has the greatest thickness in the center of the display panel PNL (display area DA) and decreases in thickness as it approaches the light source units LU1 and LU2 from the center. The organic insulating layer 22 is formed, for example, in a stepped shape.

[0123] In contrast, the inorganic insulating layer 21 has multiple portions in which the thickness gradually decreases from the sides E2a and E2b toward the center. The main surface F7 of the inorganic insulating layer 21 is parallel to the XY plane defined by the first direction X and the second direction Y. Focusing on the liquid crystal layer LC, the thickness of the liquid crystal layer LC is approximately constant in the second direction Y.

[0124] The organic insulating layer 22 has varying thickness depending on its position in the YZ plane, but its thickness remains constant in the XZ plane. Focusing on the alignment film AL2, the alignment film AL2 is approximately parallel to the XY plane, as shown in Figure 15.

[0125] In this embodiment as well, the same effects as those of the second and third embodiments can be obtained.

[0126] In the first to fourth embodiments, examples were disclosed in which the inorganic insulating layer 21 is formed in a stepped shape, but the inorganic insulating layer 21 may be inclined in the second direction Y. Also, the shape of the organic insulating layer 22 can be appropriately changed according to the shape of the inorganic insulating layer 21.

[0127] All display devices that a person skilled in the art can implement by appropriately modifying the design based on the display devices described above as embodiments of the present invention also fall within the scope of the present invention insofar as they encompass the gist of the present invention. Within the scope of the idea of ​​the present invention, a person skilled in the art can conceive of various modifications, and these modifications are also understood to fall within the scope of the present invention. For example, any modifications made by a person skilled in the art to add, delete, or modify components, or to add, omit, or change the conditions of the above-described embodiments, are also included within the scope of the present invention insofar as they retain the gist of the present invention.

[0128] Furthermore, any other effects and advantages brought about by the embodiments described above that are obvious from the description herein or that can be appropriately conceived by those skilled in the art are naturally considered to be brought about by the present invention. [Explanation of Symbols]

[0129] 10...First transparent substrate, 20...Second transparent substrate, 21...Inorganic insulating layer, 22...Organic insulating layer, AL1, AL2...Alignment film, CE...Common electrode, CM1...Cover member, DA...Display area, DSP...Display device, LC...Liquid crystal layer, LC1, LC2, LC3...Liquid crystal section, LU1, LU2...Light source unit, P1, P2, P3...Part, PE...Pixel electrode, PNL...Display panel, PX...Pixel, RF...Reflective material, SUB1...First substrate, SUB2...Second substrate.

Claims

1. A display device having a liquid crystal layer containing polymer-dispersed liquid crystal, which can switch between a state in which light incident on the liquid crystal layer is transmitted and a state in which light is scattered, depending on the applied voltage, A display panel having a first side, The system comprises a first light source unit arranged along the first side surface, The aforementioned display panel is A first transparent substrate having a first main surface, A second transparent substrate having a second main surface facing the first main surface, The liquid crystal layer disposed between the first transparent substrate and the second transparent substrate, A first electrode disposed between the liquid crystal layer and the first main surface, A second electrode is disposed between the liquid crystal layer and the second main surface, The system comprises an inorganic insulating layer disposed between the second electrode and the liquid crystal layer, and having a dielectric constant different from that of the liquid crystal layer, As the distance from the first light source unit increases, the thickness of the inorganic insulating layer decreases. Display device.

2. The inorganic insulating layer has a first portion and a second portion whose distance from the first light source unit is greater than the distance from the first light source unit to the first portion. The first portion has a first thickness, The second portion has a second thickness that is smaller than the first thickness. The display device according to claim 1.

3. The liquid crystal layer has a first liquid crystal portion overlapping the first portion and a second liquid crystal portion overlapping the second portion. The first liquid crystal portion has a third thickness, The second liquid crystal portion has a fourth thickness that is greater than the third thickness. The display device according to claim 2.

4. The thickness of the inorganic insulating layer is less than or equal to half the distance between the first electrode and the second electrode. The display device according to claim 1.

5. The device further comprises an organic insulating layer disposed between the second electrode and the liquid crystal layer, The dielectric constant of the organic insulating layer differs from that of the liquid crystal layer and the inorganic insulating layer. The organic insulating layer has a thickness that increases as it moves away from the first light source unit. The display device according to claim 1.

6. The thickness of the liquid crystal layer is substantially constant in the direction away from the first light source unit. The display device according to claim 5.

7. The organic insulating layer is disposed between the inorganic insulating layer and the liquid crystal layer. The display device according to claim 5.

8. The inorganic insulating layer is formed in a stepped shape, with its thickness decreasing in the direction away from the first light source unit. The display device according to claim 1.

9. The distance between the first electrode and the second electrode is approximately constant in the direction away from the first light source unit. The display device according to any one of claims 1 to 8.

10. A first alignment film disposed between the liquid crystal layer and the first electrode, The system comprises a second alignment film disposed between the liquid crystal layer and the inorganic insulating layer, The display device according to claim 9.

11. A display device having a liquid crystal layer containing polymer-dispersed liquid crystal, which can switch between a state in which light incident on the liquid crystal layer is transmitted and a state in which light is scattered, depending on the applied voltage, A display panel having a first side and a second side, A first light source unit arranged along the first side surface, The system comprises a second light source unit arranged along the second side surface, The aforementioned display panel is A first transparent substrate having a first main surface, A second transparent substrate having a second main surface facing the first main surface, The liquid crystal layer disposed between the first transparent substrate and the second transparent substrate, A first electrode disposed between the liquid crystal layer and the first main surface, A second electrode is disposed between the liquid crystal layer and the second main surface, The device comprises an inorganic insulating layer disposed between the aforementioned second electrode and the liquid crystal layer, The inorganic insulating layer has the smallest thickness in the central part of the display panel, and its thickness increases as it approaches the first light source unit and the second light source unit from the central part. Display device.

12. The inorganic insulating layer has a first portion, a second portion, and a third portion. The first light source unit, the first part, the second part, the third part, and the second light source unit are arranged in this order in the direction away from the first light source unit. The first portion has a first thickness, The second portion has a second thickness that is smaller than the first thickness. The third portion has a fifth thickness that is greater than the second thickness. The display device according to claim 11.

13. The liquid crystal layer has a first liquid crystal portion overlapping the first portion, a second liquid crystal portion overlapping the second portion, and a third liquid crystal portion overlapping the third portion. The first liquid crystal portion has a third thickness, The second liquid crystal portion has a fourth thickness that is greater than the third thickness. The third liquid crystal portion has a sixth thickness that is smaller than the fourth thickness. The display device according to claim 12.

14. The thickness of the inorganic insulating layer is less than or equal to half the distance between the first electrode and the second electrode. The display device according to claim 11.

15. The device further comprises an organic insulating layer disposed between the second electrode and the liquid crystal layer, The dielectric constant of the organic insulating layer differs from that of the liquid crystal layer and the inorganic insulating layer. The organic insulating layer has the greatest thickness in the central part of the display panel, and its thickness decreases as it approaches the first light source unit and the second light source unit from the central part. The display device according to claim 11.

16. The organic insulating layer is disposed between the second electrode and the liquid crystal layer. The display device according to claim 15.

17. The distance between the first electrode and the second electrode is approximately constant in the direction away from the first light source unit. The display device according to any one of claims 11 to 16.

18. A first alignment film disposed between the liquid crystal layer and the first electrode, The system comprises a second alignment film disposed between the liquid crystal layer and the inorganic insulating layer, The display device according to claim 17.

19. A display panel having multiple pixels and a first side surface, The system comprises a first light source unit arranged along the first side surface, The aforementioned display panel is A first transparent substrate having a first main surface, A second transparent substrate having a second main surface facing the first main surface, A liquid crystal layer disposed between the first transparent substrate and the second transparent substrate, An electrode disposed between the liquid crystal layer and the second main surface, The system comprises an inorganic insulating layer disposed between the electrode and the liquid crystal layer, overlapping with the plurality of pixels, and having a dielectric constant smaller than that of the liquid crystal layer, As the distance from the first light source unit increases, the thickness of the inorganic insulating layer decreases. Display device.

20. An alignment film is disposed between the liquid crystal layer and the inorganic insulating layer. The alignment film is in direct contact with the liquid crystal layer and the inorganic insulating layer. The display device according to claim 19.

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