Display device and opposed substrate

Abstract

To improve the performance of a display device.SOLUTION: A display device includes: an array substrate SUB1 having switching elements; and an opposed substrate SUB2 provided opposed to the array substrate SUB1. The opposed substrate SUB2 includes: a substrate 20 having translucency; and an overcoat film OC1 contacting with the substrate 20. The overcoat film OC1 comprises a plurality of types of films having different refractive indexes.SELECTED DRAWING: Figure 14

Description

[Technical field]

[0001] The present invention relates to a display device and a counter substrate. [Background technology]

[0002] Japanese Patent Application Laid-Open No. 2017-203849 (Patent Document 1) describes a technique for preventing color mixing and brightness reduction as well as preventing contamination of liquid crystal. Specifically, Patent Document 1 describes a technique for arranging a light-shielding layer close to the array substrate by using a first light-transmitting resin layer and a second light-transmitting resin layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-203849 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, there are display devices used in applications where it is desirable to widen the viewing angle, while there are also display devices used in applications where a large viewing angle is not required. In such display devices used in applications where a large viewing angle is not required, there is room for ingenuity in prioritizing improvement of other performances over widening the viewing angle. [Means for solving the problem]

[0005] A display device according to an embodiment includes an array substrate having switching elements, and a counter substrate arranged opposite the array substrate, the counter substrate including a light-transmitting substrate and an overcoat film in contact with the substrate, the overcoat film being made of a plurality of types of films having different refractive indices.

[0006] The counter substrate in one embodiment is a component of a display device. Here, the counter substrate includes a light-transmitting substrate and an overcoat film in contact with the substrate, and the overcoat film is composed of multiple types of films with different refractive indices. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an exploded perspective view showing a schematic configuration example of a liquid crystal display device. [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of a display panel. [Diagram 3] FIG. 2 is a plan view showing an example of a planar layout of sub-pixels. [Figure 4] FIG. 2 is a schematic plan view showing some of the elements that constitute a sub-pixel. [Diagram 5] FIG. 5 is a schematic cross-sectional view taken along line AA in FIG. 4. [Figure 6] 1A and 1B are schematic diagrams illustrating examples of the configuration of a conductive film. [Figure 7] FIG. 5 is a simplified schematic diagram of FIG. 4, showing a planar layout of scanning lines, signal lines and conductive films provided on the array substrate. [Figure 8] 2 is a plan view showing an overcoat film which is a component of a counter substrate disposed above an array substrate; FIG. [Figure 9] 8. FIG. 8 is a schematic cross-sectional view taken along line AA in FIG. 7 and line AA in FIG. [Figure 10] This is a diagram expressing "oblique light." [Figure 11] FIG. 1 is a diagram showing a planar layout of an overcoat film in an embodiment; [Figure 12] 12 is a cross-sectional view taken along line AA in FIG. 7 and line AA in FIG. 11. [Figure 13] 12 is a cross-sectional view taken along line BB in FIG. 7 and line BB in FIG. 11. [Figure 14] 11 is a diagram for explaining a change in the traveling direction of "oblique light." [Figure 15]FIG. 11 is a plan view showing an overcoat film which is a component of a counter substrate disposed above an array substrate in the first modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments will be described with reference to the drawings.

[0009] Note that the present disclosure is merely an example, and any modifications that a person skilled in the art can easily conceive of while maintaining the gist of the present disclosure are naturally included within the scope of the present disclosure.

[0010] In addition, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present disclosure. In this specification and each drawing, elements similar to those shown in the previous drawings are given the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0011] In the present embodiment, as an example, a liquid crystal display device having a liquid crystal display element is disclosed. However, the embodiment does not prevent the application of the technical ideas disclosed in the embodiment to a display device having other types of display elements such as an organic electroluminescence display element, a micro LED, or a mini LED. In addition, the technical ideas disclosed in the embodiment can also be applied to an array substrate and an electronic device having a sensor element such as a capacitance sensor or an optical sensor.

[0012] <Overall configuration of liquid crystal display device> FIG. 1 is an exploded perspective view showing a schematic configuration example of a liquid crystal display device 1. As shown in FIG. As shown in Fig. 1, the X direction, Y direction, and Z direction are defined. The X direction, Y direction, and Z direction are mutually orthogonal, but may intersect at an angle other than a perpendicular angle. Viewing the liquid crystal display device 1 or its components parallel to the Z direction is called a "planar view." The direction indicated by the Z direction arrow is sometimes called "upward," and the opposite direction is sometimes called "downward."

[0013] 1, a liquid crystal display device 1 includes a display panel 2 and a backlight 3. For example, the backlight 3 can be configured as a side-edge type backlight including a light guide LG facing the display panel 2 and a plurality of light-emitting elements LS arranged at positions facing the side surfaces of the light guide LG. However, the backlight 3 is not limited to this, and backlights of various configurations that can supply light necessary for image display can be adopted.

[0014] The planar shapes of the display panel 2 and the light guide LG are, for example, rectangular shapes having long sides along the X direction and short sides along the Y direction, but are not limited to rectangular shapes and may be other shapes.

[0015] The display panel 2 is a liquid crystal panel having light transmissibility, and includes, for example, an array substrate SUB1, a counter substrate SUB2 facing the array substrate SUB1, and a liquid crystal layer LC sealed between the array substrate SUB1 and the counter substrate SUB2. The display panel 2 thus configured has, for example, a rectangular display area DA.

[0016] The liquid crystal display device 1 further includes an optical sheet group 4, and polarizing plates 5 and 6. The optical sheet group 4 is disposed between the light guide LG and the display panel 2. For example, the optical sheet group 4 includes a diffusion sheet DF that diffuses the light emitted from the light guide LG, and a prism sheet PR1 and a prism sheet PR2, each of which has a large number of prisms formed thereon.

[0017] The polarizing plate 5 is disposed between the optical sheet group 4 and the array substrate SUB1. On the other hand, the polarizing plate 6 is disposed above the counter substrate SUB2. Here, the polarization axis of the polarizing plate 5 and the polarization axis of the polarizing plate 6 are in a crossed Nicol relationship in which they are perpendicular to each other.

[0018] The liquid crystal display device 1 configured in this manner can be used in various types of devices, such as head mounted displays, in-vehicle devices, smartphones, tablet terminal devices, mobile phones, personal computers, television receivers, and game devices.

[0019] <Display panel configuration> Next, the configuration of the display panel 2 will be described. FIG. 2 is a diagram showing a schematic configuration of the display panel 2. As shown in FIG. 2, the display panel 2 has a display area DA and a peripheral area SA around the display area DA. For example, as shown in FIG. 2, the lower side of the array substrate SUB1 protrudes in the Y direction further than the counter substrate SUB2. As a result, the array substrate SUB1 has a mounting area MA that does not overlap with the counter substrate SUB2 in a plan view. This mounting area MA constitutes a part of the peripheral area SA.

[0020] In the display area DA, a plurality of pixels PX are arranged in a matrix. Each pixel PX includes a plurality of sub-pixels. For example, in FIG. 2, the pixel PX includes a red sub-pixel SPR, a green sub-pixel SPG, and a blue sub-pixel SPB. However, the pixel PX is not limited to this configuration, and may be configured to include sub-pixels of other colors, typically white.

[0021] As shown in Fig. 2, the display panel 2 includes a plurality of scanning lines G, a plurality of signal lines S (video lines), a scanning driver GD1, a scanning driver GD2, and a selector circuit ST. The plurality of scanning lines G extend in the X direction and are arranged in the Y direction. In contrast, the plurality of signal lines S extend in the Y direction and are arranged in the X direction. Each of the plurality of scanning lines G is connected to the scanning driver GD1 or the scanning driver GD2. Meanwhile, each of the plurality of signal lines S is connected to the selector circuit ST.

[0022] 2, a controller CT is mounted in the mounting area MA. A terminal portion T is provided in the mounting area MA, and a flexible substrate F is connected to the terminal portion T. The controller CT may be mounted on the flexible substrate F. The controller CT is formed of, for example, an IC chip or a circuit element.

[0023] Various types of signals transmitted from an electronic device in which the liquid crystal display device 1 is implemented are output to the controller CT via an integrated circuit mounted on the flexible substrate F. The controller CT inputs these signals and supplies a video signal to the selector circuit ST, while controlling the scan driver GD1, the scan driver GD2, and the selector circuit ST.

[0024] Each of the scan driver GD1 and the scan driver GD2 sequentially supplies scan signals to the plurality of scan lines G. On the other hand, the selector circuit ST sequentially supplies a video signal input from the controller CT to the signal lines S.

[0025] Each pixel PX includes a pixel electrode PE, a switching element SW (thin film transistor), and a common electrode CE to which a common potential is supplied. The switching element SW is connected to the pixel electrode PE, the scanning line G, and the signal line S.

[0026] For example, when the switching element SW is composed of a thin film transistor (field effect transistor), the gate electrode of the thin film transistor is electrically connected to the scanning line G. In addition, the source of the thin film transistor is electrically connected to the signal line S, while the drain of the thin film transistor is electrically connected to the pixel electrode PE.

[0027] When a scanning signal is supplied to the scanning line G, the thin film transistor is turned on and the video signal supplied to the signal line S is supplied to the pixel electrode PE. Meanwhile, the common electrode CE is formed across multiple sub-pixels, and when a video signal is supplied to the pixel electrode PE, a potential difference is generated between the pixel electrode PE and the common electrode CE. The electric field generated by this acts on the liquid crystal layer LC, thereby controlling the alignment direction of the multiple liquid crystal molecules that make up the liquid crystal layer LC.

[0028] For example, in the so-called "vertical electric field method," in which a pixel electrode PE is formed on an array substrate while a common electrode CE is formed on an opposing substrate, and a liquid crystal layer LC is sandwiched between the pixel electrode PE and the common electrode CE, the orientation direction of the multiple liquid crystal molecules that make up the liquid crystal layer LC is controlled by the vertical electric field generated between the pixel electrode PE and the common electrode CE.

[0029] On the other hand, in the so-called "horizontal electric field method," for example, a pixel electrode PE and a common electrode CE are formed on an array substrate, and a horizontal electric field (fringe electric field) leaking from a slit provided in the common electrode CE is utilized, the orientation direction of multiple liquid crystal molecules constituting the liquid crystal layer LC arranged above the array substrate is controlled by the horizontal electric field leaking from the slit.

[0030] As described above, there are two methods for controlling the alignment direction of liquid crystal molecules: the "vertical electric field method" and the "horizontal electric field method." For example, the "horizontal electric field method" has the advantage of being able to provide a wider viewing angle than the "vertical electric field method." In this embodiment, the "horizontal electric field method" is adopted, and the scanning lines G, signal lines S, scanning drivers GD1 and GD2, selector circuits ST, switching elements SW, pixel electrodes PE, and common electrodes CE are formed on the array substrate SUB1.

[0031] <Plane layout configuration of sub-pixels> Next, the planar layout configuration of the sub-pixels will be described. FIG. 3 is a plan view showing an example of a planar layout of sub-pixels. 3, the subpixels are subpixels SPR, SPG, and SPB. A red color filter CFR is disposed in the subpixel SPR, a green color filter CFG is disposed in the subpixel SPG, and a blue color filter CFB is disposed in the subpixel SPB.

[0032] 3, the subpixels SPR, SPG, and SPB are arranged in the X direction in this order. Also, the subpixels SPR, SPB, and SPG are arranged in the Y direction in this order. As a result, the subpixels SPR are arranged in a diagonal direction intersecting the X and Y directions. Similarly, the subpixels SPG are arranged in a diagonal direction, and the subpixels SPB are arranged in a diagonal direction.

[0033] The color filters CFR, CFG, and CFB are arranged in a dot shape (island shape) with respect to the subpixels SPR, SPG, and SPB.

[0034] For example, gaps GP are formed between color filters CFR and CFG adjacent to each other in the Y direction, between color filters CFG and CFB, and between color filters CFB and CFR.

[0035] It should be noted that the planar layout of the subpixels SPR, SPG, and SPB and the color filters CFR, CFG, and CFB is not limited to the planar layout shown in FIG.

[0036] For example, the subpixels SPR may be arranged in the Y direction, the subpixels SPG may be arranged in the Y direction, and the subpixels SPB may be arranged in the Y direction, with the columns of the subpixels SPR, the columns of the subpixels SPG, and the columns of the subpixels SPB arranged in order in the X direction.

[0037] As described above, the liquid crystal display device 1 in the present embodiment has a so-called "COA (Color Filter on Array) structure" in which all of the color filters CFR, CFG, and CFB are disposed on the array substrate SUB1. According to the "COA structure," the color filters and the sub-pixels are provided on the same array substrate SUB1. Therefore, according to the "COA structure," a high-definition liquid crystal display device 1 can be realized without being affected by misalignment between the array substrate SUB1 and the counter substrate SUB2. FIG. 4 is a schematic plan view showing some of the elements that constitute a sub-pixel.

[0038] 4 shows two scanning lines G extending in the X direction and two signal lines S extending in the Y direction intersecting the scanning lines G. An aperture region OR of a sub-pixel is formed in a region surrounded by the two scanning lines G and the two signal lines S. A pixel electrode PE is provided in the aperture region OR so as to overlap the aperture region OR in a plan view.

[0039] A conductive film TML is disposed above the scanning lines G and the signal lines S. This conductive film TML has an X-direction extending portion extending in the X direction and a Y-direction extending portion extending in the Y direction. The X-direction extending portion is provided so as to overlap with the scanning lines G in a planar view. On the other hand, the Y-direction extending portion is provided so as to overlap with the signal lines S in a planar view. Due to these X-direction extending portion and Y-direction extending portion, the conductive film TML has an overall lattice-like planar shape as shown in FIG. 4. This conductive film TML functions as a "light-shielding film" that blocks light.

[0040] 4, the signal line S is connected to the semiconductor layer OS of the thin film transistor constituting the switching element at the contact portion PLG1. That is, the semiconductor layer OS is in contact with the signal line S at the contact portion PLG1. In this manner, the contact portion PLG1 has a function of electrically connecting the semiconductor layer OS and the signal line S.

[0041] The semiconductor layer OS also extends to intersect with the scanning line G and reach the opening region OR, and is connected to the relay electrode RE at the contact portion PLG2 inside the opening region OR. Therefore, the semiconductor layer OS is electrically connected to the relay electrode RE through the contact portion PLG2. That is, the contact portion PLG2 has a function of electrically connecting the semiconductor layer OS and the relay electrode RE.

[0042] Furthermore, a pixel electrode PE is provided so as to overlap the opening region OR in a plan view, and this pixel electrode PE and the relay electrode RE are connected at the bottom of the contact portion PLG3. That is, a part of the pixel electrode PE is formed inside the contact portion PLG3, and the part of the pixel electrode PE formed inside the contact portion PLG3 and the relay electrode RE are electrically connected at the bottom of the contact portion PLG3. From the above, the pixel electrode PE is electrically connected to the semiconductor layer OS via the relay electrode RE. That is, the contact portion PLG3 has the function of electrically connecting the pixel electrode PE and the relay electrode RE.

[0043] 4, a common electrode CE is provided so as to overlap in plan with all of the elements such as the scanning lines G, the signal lines S, and the conductive film TML, etc. In the opening region OR, a slit SL is provided in the common electrode CE.

[0044] Here, for example, an electric field generated when a potential difference is generated between the common electrode CE and the pixel electrode PE leaks out from the slit SL provided in the common electrode CE. As a result, the lateral electric field leaking out from the slit SL controls the alignment direction of a plurality of liquid crystal molecules constituting the liquid crystal layer disposed above the array substrate. In other words, the slit SL provided in the common electrode CE has the function of applying a lateral electric field to the liquid crystal layer to control the alignment direction of a plurality of liquid crystal molecules. In this manner, the planar layout configuration of the sub-pixels is realized.

[0045] <Cross-sectional structure of sub-pixel> Next, the cross-sectional structure of the sub-pixel will be described. Fig. 5 is a schematic cross-sectional view taken along line AA in Fig. 4. Note that Fig. 5 is a schematic cross-sectional view and does not accurately reflect the cross-section along line AA in Fig. 4. For example, line AA in Fig. 4 intersects with scanning line G twice, but only one scanning line G (gate electrode GE1) is shown in Fig. 5. Also, gate electrode GE2 is shown in Fig. 5, but this gate electrode GE2 is not shown in Fig. 4.

[0046] 5, an insulating layer IL1 is formed on a light-transmitting substrate 10. An insulating layer IL2 is formed on the insulating layer IL1. The substrate 10 is made of, for example, glass, but is not limited to this and may be made of a resin material such as polyimide resin. The insulating layers IL1 and IL2 are made of inorganic insulating films such as silicon nitride films and silicon oxide films.

[0047] 5, a gate electrode GE1 of a thin film transistor (field effect transistor) serving as a switching element is formed on the insulating layer IL2. This gate electrode GE1 functions as a scanning line G. The gate electrode GE1 is made of, for example, a metal material. The gate electrode GE1 may have a single-layer structure made of a single metal material, or may have a multi-layer structure in which different types of metal materials are laminated.

[0048] Next, an insulating layer IL3 is formed on the insulating layer IL2 so as to cover the gate electrode GE1. A semiconductor layer OS is formed on the insulating layer IL3. The insulating layer IL3 is made of an inorganic insulating film such as a silicon nitride film or a silicon oxide film. On the other hand, the semiconductor layer OS is made of an amorphous silicon film or an oxide semiconductor film.

[0049] The semiconductor layer OS functions as a channel of the thin film transistor. That is, a channel is formed in the semiconductor layer OS based on a gate voltage applied to the gate electrode GE1. For example, when a gate voltage equal to or greater than a threshold voltage is applied to the gate electrode GE1, a channel is formed in the semiconductor layer OS. On the other hand, when a gate voltage less than the threshold voltage is applied to the gate electrode GE1, the channel formed in the semiconductor layer OS disappears.

[0050] This makes it possible to control the on / off operation of the thin film transistor based on the gate voltage applied to the gate electrode GE1.

[0051] For example, the semiconductor layer OS is desirably formed of an oxide semiconductor film, because a thin film transistor using an oxide semiconductor film as a channel has an advantage of having higher electron mobility and a very low off-leakage current than a thin film transistor using an amorphous silicon film as a channel.

[0052] 5, an insulating layer IL4 is formed on the insulating layer IL3 so as to cover the semiconductor layer OS. Then, a gate electrode GE2 is formed on the insulating layer IL4. The insulating layer IL4 is made of an inorganic insulating film such as a silicon nitride film or a silicon oxide film. On the other hand, the gate electrode GE2 is made of a metal material, for example. In this manner, the thin-film transistor has the gate electrodes GE1 and GE2 arranged to sandwich the semiconductor layer OS from above and below. In this configuration, for example, a channel can be formed on the lower surface of the semiconductor layer OS by applying a gate voltage equal to or higher than the threshold voltage to the gate electrode GE1 arranged below the semiconductor layer OS, and a channel can also be formed on the upper surface of the semiconductor layer OS by applying a gate voltage equal to or higher than the threshold voltage to the gate electrode GE2 arranged above the semiconductor layer OS.

[0053] That is, in the thin film transistor of the present embodiment, since channels can be formed on both the upper and lower surfaces of the semiconductor layer OS, the current driving force of the thin film transistor can be improved. However, the configuration of the thin film transistor is not limited to this, and the gate electrode GE2 may be omitted. For this reason, for example, the gate electrode GE2 is not illustrated in FIG. 4.

[0054] Next, an insulating layer IL5 is formed on the insulating layer IL4 so as to cover the gate electrode GE2. Then, a source electrode SE is formed on the insulating layer IL5. This source electrode SE functions as a signal line S. The insulating layer IL5 is made of an inorganic insulating film such as a silicon nitride film or a silicon oxide film. On the other hand, the source electrode SE is made of a metal material, for example.

[0055] Here, as shown in FIG. 5, a contact hole CH1 is formed in the insulating layer IL4 and the insulating layer IL5, penetrating these insulating layers to reach the semiconductor layer OS, and through this contact hole CH1, the source electrode SE is electrically connected to the semiconductor layer OS.

[0056] Next, an insulating layer IL6 is formed on the insulating layer IL5 so as to cover the source electrode SE. This insulating layer IL6 is also made of an inorganic insulating film such as a silicon nitride film or a silicon oxide film. Then, as shown in FIG. 5, a contact hole CH2 is formed penetrating the insulating layer IL6, the insulating layer IL5, and the insulating layer IL4 to reach the semiconductor layer OS. At this time, a relay electrode RE is formed from inside the contact hole CH2 over the insulating layer IL6. The relay electrode RE is made of, for example, a light-transmitting conductive material.

[0057] Subsequently, an insulating layer IL7 is formed so as to cover the relay electrode RE inside the contact hole CH2 and over the insulating layer IL6. The insulating layer IL7 is also made of an inorganic insulating film such as a silicon nitride film or a silicon oxide film.

[0058] As a result, the relay electrode RE is electrically connected to the semiconductor layer OS at the contact portion PLG2. In other words, the relay electrode RE is electrically connected to the drain of the thin film transistor.

[0059] Then, as shown in FIG. 5, the color filter CFB and the color filter CFG are formed on the insulating layer IL7. This realizes a "COA structure" in this embodiment. Next, an organic insulating film 100A is formed so as to cover the color filter CFB and the color filter CFG. The organic insulating film 100A is made of an organic material such as an acrylic resin. A contact hole CH3 is formed in the organic insulating film 100A and the insulating layer IL7, penetrating the organic insulating film 100A and the insulating layer IL7 and reaching the relay electrode RE. A plurality of types of components are embedded in the contact hole CH3 to form a contact portion PLG3. In this manner, the contact portion PLG3 is electrically connected to the semiconductor layer OS (drain side) via the relay electrode RE.

[0060] Next, the internal and external configuration of the contact portion PLG3 will be described. 5, a relay electrode RE is provided on an insulating layer IL6, and an insulating layer IL7 is disposed so as to cover the relay electrode RE. A color filter CFB and a color filter CFG are provided on the insulating layer IL7. In order to flatten the unevenness caused by the color filter CFB and the color filter CFG, an organic insulating film 100A is provided so as to cover the color filter CFB and the color filter CFG.

[0061] As shown in FIG. 5, the organic insulating film 100A has a contact hole CH3 penetrating the organic insulating film 100A and the insulating layer IL7 to reach the relay electrode RE. A pixel electrode PE made of a light-transmitting conductive material such as ITO is formed on the inner wall of the contact hole CH3. As shown in FIG. 5, the pixel electrode PE is electrically connected to the relay electrode RE at the bottom of the contact hole CH3. Furthermore, a capacitive insulating film CI is formed in the contact hole CH3 and in contact with the pixel electrode PE and the inner wall of the contact hole CH3. The capacitive insulating film CI is made of, for example, a silicon nitride film. Next, a conductive film TML in contact with the capacitive insulating film CI, a common electrode CE in contact with the conductive film TML, and an organic insulating film 100B in contact with the common electrode CE and filling the contact hole CH3 are formed in the contact hole CH3.

[0062] Here, a capacitance is formed by the pixel electrode PE, the capacitance insulating film CI, and the common electrode CE, and when a potential difference is generated between the pixel electrode PE and the common electrode CE, an electric field is induced between the pixel electrode PE and the common electrode CE. Although not shown in Fig. 5, a slit is provided in the common electrode CE, and the alignment direction of the liquid crystal molecules is controlled based on the electric field leaking from the slit.

[0063] The common electrode CE is made of a transparent conductive material such as ITO. In order to reduce the resistance of the common electrode CE, a conductive film TML is provided in contact with the common electrode CE. In other words, the conductive film TML has the function of reducing the resistance of the common electrode CE.

[0064] An example of the configuration of the conductive film TML will be described below. FIG. 6 is a schematic diagram showing a configuration example of the conductive film TML.

[0065] 6, the conductive film TML is composed of a laminated film of a titanium film 310, an aluminum film 320, a titanium film 330, an ITO film 340, and a molybdenum film 350. That is, the conductive film TML is composed to include a metal film and a transparent conductive film (metal oxide film). For example, the titanium film 310, the aluminum film 320, the titanium film 330, and the molybdenum film 350 which constitute a part of the conductive film TML are metal films with low resistance, and therefore these metal films have the function of reducing the resistance of the common electrode CE.

[0066] On the other hand, the ITO film 340 is a light-transmitting conductive film, and is configured so that the phase difference between the light transmitted through the ITO film 340 and reflected by the titanium film 330 and the light reflected by the surface of the ITO film 340 is 180 degrees. As a result, the light transmitted through the ITO film 340 and reflected by the titanium film 330 and the light reflected by the surface of the ITO film 340 are offset by interference, and the reflection of external light is suppressed. Also, as shown in FIG. 5, the common electrode CE is disposed so as to be in contact with the conductive film TML. As a result, the common electrode CE is in contact with the molybdenum film 350 constituting the conductive film TML. Here, the common electrode CE is made of a light-transmitting conductive material such as ITO, and is configured so that the phase difference between the light transmitted through the common electrode CE and reflected by the molybdenum film 350 and the light reflected by the surface of the common electrode CE is 180 degrees. As a result, the light that has passed through the common electrode CE and is reflected by the molybdenum film 350 and the light that has been reflected by the surface of the common electrode CE are offset by interference, thereby suppressing the reflection of external light. In this way, the conductive film TML also functions as an anti-reflection film that suppresses the reflection of external light.

[0067] 5, a liquid crystal layer LC is disposed above the organic insulating film 100B formed on the contact portion PLG3 via an alignment film 200A, and a spacer SP is provided above the contact portion PLG3. A substrate 20 is disposed above the liquid crystal layer LC via the alignment film 200B and an overcoat film OC. In this manner, the cross-sectional structure of the sub-pixel is realized.

[0068] <Description of Related Art> Next, the related art will be described with reference to schematic diagrams. The term "related art" as used herein refers to art that is not publicly known, but has problems that the inventors have found, and is a technology that serves as a premise for the present invention.

[0069] FIG. 7 is a schematic diagram that simplifies FIG. 4, and shows a planar layout of the scanning lines G, signal lines S and conductive films TML provided on the array substrate.

[0070] FIG. 7 shows two scanning lines G extending in the X direction and two signal lines S extending in the Y direction intersecting the scanning lines G. A conductive film TML is disposed above the scanning lines G and the signal lines S. The conductive film TML has an X-direction extending portion extending in the X direction and a Y-direction extending portion extending in the Y direction. The X-direction extending portion is provided so as to overlap with the scanning lines G in a plan view. On the other hand, the Y-direction extending portion is provided so as to overlap with the signal lines S in a plan view. Due to the X-direction extending portion and the Y-direction extending portion, the conductive film TML has a lattice-like planar shape as a whole, as shown in FIG. 7. An aperture region OR of a sub-pixel is formed in a region surrounded by the two scanning lines G and the two signal lines S.

[0071] Next, Fig. 8 is a plan view showing an overcoat film OC, which is a component of the counter substrate arranged above the array substrate. That is, Fig. 8 shows the overcoat film OC arranged above the schematic diagram shown in Fig. 7. As shown in Fig. 8, in the related technology, the overcoat film OC is composed of a single film that is not patterned. This overcoat film OC is composed of a light-transmitting resin material such as acrylic resin. For example, the overcoat film OC in the related technology has a refractive index of about 1.5.

[0072] In this specification, a film with a refractive index of about 1.5 is called a "low refractive index film," while a film with a refractive index of 1.7 to 1.9 is called a "high refractive index film." In this case, the overcoat film OC in the related technology can be said to be a single low refractive index film that is not patterned. Note that each of the substrates 10 and 20 is, for example, a glass substrate, and the refractive index of the glass substrate is about 1.5. In other words, the "high refractive index film" can be said to be a film having a refractive index higher than that of the substrates 10 and 20. On the other hand, the overcoat film OC in the related technology can be said to be a film having a refractive index similar to that of the substrates 10 and 20.

[0073] FIG. 9 is a schematic cross-sectional view taken along the line AA in FIG. 7 and the line AA in FIG. 9, an array substrate SUB1 is disposed above a backlight 3, and a counter substrate SUB2 is disposed opposite the array substrate SUB1. As shown in FIG 9, a liquid crystal layer LC is sealed between the array substrate SUB1 and the counter substrate SUB2. A polarizing plate 5 is disposed between the backlight 3 and the array substrate SUB1, while a polarizing plate 6 is disposed above the counter substrate SUB2.

[0074] Next, the main components of the array substrate SUB1 will be briefly described. The array substrate SUB1 has a light-transmitting substrate 10, on which gate electrodes GE1 (scanning lines G) of thin-film transistors constituting switching elements are provided. As shown in FIG. 9, the array substrate SUB1 is provided with a plurality of color filters CF arranged apart from each other, realizing a "COA structure." An organic insulating film 100A is formed so as to cover these color filters CF. Furthermore, the array substrate SUB1 is provided with a conductive film TML and a common electrode CE in contact with the conductive film TML.

[0075] In contrast, the counter substrate SUB2 has a light-transmitting substrate 20 and an overcoat film OC in contact with the substrate 20. The overcoat film OC is made of, for example, a light-transmitting resin material. This overcoat film OC has the function of increasing the flatness of the surface (lower surface) of the counter substrate SUB2 and the function of suppressing the diffusion of impurities into the liquid crystal layer LC.

[0076] In the related technology configured in this manner, for example, as shown in Fig. 10, "oblique light" is generated from inside the opening region OR toward the outside of the opening region OR. Therefore, in the related technology, the viewing angle of the display device can be secured by the "oblique light." Therefore, the related technology is effective when applied to a display device used for purposes in which it is desirable to widen the viewing angle.

[0077] However, for example, while there are display devices used in applications where it is desirable to widen the viewing angle, there are also display devices used in applications where a large viewing angle is not required. In display devices used in such applications, "oblique light" is not necessary.

[0078] For example, head mounted displays use an optical system that forms an image using lenses, making oblique light unnecessary. Also, for display devices used in smartphones and other devices, there is a demand to prevent people nearby from peeking at the display screen, and a display device that meets this demand desirably has a narrow viewing angle.

[0079] That is, there are applications in which it is desirable to reduce "oblique light" in display devices. For this reason, it may be desirable to focus on reducing "oblique light" and improving other performances as a priority, rather than focusing on widening the viewing angle.

[0080] Therefore, in this embodiment, attention is paid to a display device used for an application that does not require a viewing angle, and a device is devised to improve the brightness in the front direction, rather than widening the viewing angle. That is, in this embodiment, attention is paid to the brightness in the front direction as a performance for reducing and improving "oblique light", and the objective is to improve the brightness in the front direction. The technical idea of ​​this embodiment that employs this device will be described below.

[0081] It should be noted that the "front direction" means, for example, the "+Z direction" in FIG. 1, and the "front direction" is illustrated in each of FIG.

[0082] <Basic Concept of the Embodiment> The basic idea of ​​this embodiment is to provide an overcoat film provided on the opposing substrate with a structural device that changes the traveling direction of "oblique light" to the front direction. In other words, the basic idea is to provide the overcoat film with a function to change the traveling direction of light. Specifically, the basic idea is to configure the overcoat film from multiple types of films with different refractive indices.

[0083] According to this basic concept, when "oblique light" travels through an overcoat film made up of multiple types of films with different refractive indices, the traveling direction of the "oblique light" can be changed to the front direction based on the change in refractive index. As a result, according to the basic concept, the "oblique light" can be converted into light traveling in the front direction, thereby improving the brightness in the front direction.

[0084] For example, by appropriately patterning multiple types of films with different refractive indices, the direction of travel of the "oblique light" can be changed to the front direction based on the patterned shape. As a result, according to the basic concept, the brightness in the front direction can be improved. The following describes an embodiment that embodies this basic concept.

[0085] <Embodiment> First, the configuration of the array substrate in the embodiment is the same as that of the array substrate in the related art. For example, the planar layout of the scan lines G, signal lines S, and conductive film TML provided on the array substrate is as shown in FIG.

[0086] Next, Fig. 11 is a plan view showing a planar layout of the overcoat film OC1 in the embodiment. In Fig. 11, the overcoat film OC1 is composed of multiple types of insulating films with different refractive indices. Specifically, the overcoat film OC1 is composed of a low refractive index film 30 and a high refractive index film 40. The low refractive index film 30 is composed of, for example, an acrylic resin, and its refractive index is about 1.5. In contrast, the high refractive index film 40 is composed of, for example, a siloxane resin, and its refractive index is 1.7 or more and 1.9 or less.

[0087] Here, each of the low refractive index film 30 and the high refractive index film 40 is patterned. For example, as shown in FIG. 11, the planar shape of the low refractive index film 30 is a stripe shape aligned in the Y direction and extending in the X direction. As can be seen from the combination of FIG. 7 and FIG. 11, the low refractive index film 30 is provided so as to overlap the scanning line G and the conductive film TML in a planar view. On the other hand, the high refractive index film 40 is patterned so as to be disposed between the stripe-shaped low refractive index films 30. In this way, the overcoat film OC1 in the embodied embodiment is configured to include a patterned low refractive index film 30 and a patterned high refractive index film 40.

[0088] Fig. 12 is a schematic cross-sectional view taken along line AA in Fig. 7 and line AA in Fig. 11. In Fig. 12, description of the same configuration as in Fig. 9 will be omitted.

[0089] The display device includes an array substrate SUB1 having switching elements, and a counter substrate SUB2 disposed opposite to the array substrate SUB1. The counter substrate SUB2 includes a light-transmitting substrate 20 and an overcoat film OC1 in contact with the substrate 20.

[0090] The overcoat film OC1 has a low refractive index film 30 and a high refractive index film 40. At this time, as shown in FIG. 12, the high refractive index film 40 is arranged to sandwich the low refractive index film 30, and the low refractive index film 30 is provided above the gate electrode GE1 (scanning line G) which is a component of the switching element. Furthermore, in the cross-sectional view shown in FIG. 12, the cross-sectional shape of the low refractive index film 30 is tapered. That is, the cross-sectional shape of the low refractive index film 30 is trapezoidal. If the taper angle of the tapered shape is "θ" and the thickness of the overcoat film OC1 in the Z direction is "h", then, for example, θ=45 degrees and h=3 μm.

[0091] Another way of expressing the tapered cross-sectional shape of the low refractive index film 30 is that the low refractive index film 30 has a first surface (upper surface) in contact with the substrate 20 and a second surface (lower surface) opposite the first surface, and the area of ​​the second surface is larger than the area of ​​the first surface.

[0092] As described above, the overcoat film OC1 in the embodiment is configured to include the low refractive index film 30 and the high refractive index film 40, which have different refractive indices, and each of the low refractive index film 30 and the high refractive index film 40 is patterned. The overcoat film OC1 configured in this manner can be formed, for example, as shown below.

[0093] First, the high refractive index film 40 is applied onto the substrate 20. Then, the high refractive index film 40 is patterned by using photolithography and etching techniques. The patterning of the high refractive index film 40 is performed so as to form, for example, a stripe pattern in the high refractive index film 40, which is made up of a plurality of grooves aligned in the Y direction and each extending in the X direction.

[0094] Next, the low refractive index film 30 is applied onto the high refractive index film 40 so as to embed the low refractive index film 30 inside the multiple grooves that form the stripe pattern. Thereafter, unnecessary low refractive index film 30 formed on the high refractive index film 40 is removed. In this way, an overcoat film OC1 can be formed in which the low refractive index film 30 is embedded only inside the multiple grooves (stripe pattern) provided in the high refractive index film 40.

[0095] Fig. 13 is a schematic cross-sectional view taken along line BB in Fig. 7 and line BB in Fig. 11. In Fig. 13, a signal line S is disposed above a gate electrode GE1 (scanning line G). Moreover, a conductive film TML is provided above the signal line S.

[0096] Moreover, above the array substrate SUB1, a counter substrate SUB2 is disposed via a liquid crystal layer LC. This counter substrate SUB2 includes an overcoat film OC1. The overcoat film OC1 in the embodiment is composed of a plurality of types of insulating films having different refractive indices, namely, a low refractive index film 30 and a high refractive index film 40, as shown in Figs. 11 and 12, for example, but in Fig. 13 (a cross-sectional view taken along line BB in Fig. 11), only the low refractive index film 30 appears. In the manner described above, an embodiment that embodies the basic concept has been realized.

[0097] <<Features of the Realization>> Next, features of the embodiment will be described. A feature of the embodiment is that, for example, as shown in Fig. 14, the overcoat film OC1 provided on the counter substrate SUB2 is composed of a low refractive index film 30 and a high refractive index film 40 having different refractive indices, and the low refractive index film 30 is arranged so as to be sandwiched between the high refractive index films 40. In other words, the feature is that the low refractive index film 30 and the high refractive index film 40 are each patterned so that the low refractive index film 30 is sandwiched between the high refractive index films 40, and the overcoat film OC1 is composed of the patterned low refractive index film 30 and high refractive index film 40. In this case, for example, as shown in Fig. 14, it is desirable that the cross-sectional shape of the low refractive index film 30 sandwiched between the high refractive index films 40 is tapered (trapezoidal).

[0098] As a result, as shown in FIG. 14, according to the embodiment, the "oblique light" incident on the overcoat film OC1 is reflected at the boundary surface (tapered slope) between the high refractive index film 40 and the low refractive index film 30 due to the difference in refractive index. As a result, according to the embodiment, the traveling direction of the "oblique light" can be changed to the front direction. Therefore, according to the embodiment, the "oblique light" can be converted into light traveling in the front direction, so that the brightness in the front direction can be improved. That is, according to the embodiment, by adopting the characteristic point that the overcoat film OC1 is composed of the low refractive index film 30 and the high refractive index film 40, which are patterned, the "oblique light" can be reflected and converted into light traveling in the front direction.

[0099] From the above, according to the embodiment, by adopting the above-mentioned features, it is possible to effectively utilize unnecessary "oblique light" in a display device used for an application that does not require a viewing angle to improve the luminance in the front direction. Therefore, the features in the embodiment are effective when applied to a display device used for an application that does not require a viewing angle.

[0100] <Variation 1> Next, the first modified example will be described. Fig. 15 is a plan view showing an overcoat film OC1, which is a component of the counter substrate arranged above the array substrate. That is, Fig. 15 shows the overcoat film OC1 arranged above the schematic diagram shown in Fig. 7.

[0101] 15, in this first modification, the overcoat film OC1 is composed of a low refractive index film 30A, a low refractive index film 30B, and a high refractive index film 40. Here, the low refractive index film 30A is patterned into stripes aligned in the Y direction and each extending in the X direction. Similarly, the low refractive index film 30B is patterned into stripes aligned in the X direction and each extending in the Y direction.

[0102] Therefore, the planar shape of the combination of the low refractive index film 30A and the low refractive index film 30B is configured as a lattice shape as shown in Fig. 15. As can be seen from the combination of Fig. 7 and Fig. 15, in plan view, the low refractive index film 30A extends in the X direction so as to overlap with the scanning line G and the conductive film TML, while the low refractive index film 30B extends in the Y direction so as to overlap with the signal line S and the conductive film TML.

[0103] In contrast, the high-refractive index film 40 is patterned so as to be disposed between the combined shapes (lattice shapes) of the low-refractive index films 30A and 30B. That is, the high-refractive index film 40 is provided so as to fill the gaps of the lattice shapes. Therefore, the overcoat film OC1 in this modification 1 includes the patterned low-refractive index films 30A and 30B, and the patterned high-refractive index film 40.

[0104] In the present modified example 1 configured as above, the boundary surface where the reflection of the "oblique light" occurs is not only the boundary surface between the high refractive index film 40 and the low refractive index film 30A, but also the boundary surface between the high refractive index film 40 and the low refractive index film 30B. Therefore, according to this modified example, it is possible to increase the number of boundary surfaces that change the traveling direction of the "oblique light" to the front direction compared to the above-mentioned embodiment (see FIG. 11). This means that it is possible to increase the light traveling in the front direction that is generated by changing the traveling direction of the "oblique light" at the boundary surface. Therefore, according to the present modified example 1, it is possible to further improve the brightness in the front direction.

[0105] <Variation 2> Next, the second modified example will be described. In the above-mentioned embodiment, a display device having a so-called "COA structure" in which a color filter is provided on an array substrate has been described, but the technical idea of ​​this embodiment can also be widely applied to display devices in which a color filter is provided on an opposing substrate.

[0106] However, in a display device in which a color filter is provided on the opposing substrate, even if the "oblique light" is reflected and converted into light traveling in the front direction, a part of the light traveling in the front direction is blocked by the black matrix, so that in this modified example 2, the luminance in the front direction can be improved by applying the technical idea of ​​this embodiment, but a greater effect can be obtained by applying the technical idea of ​​this embodiment to a display device with a "COA structure".

[0107] That is, when the technical idea of ​​this embodiment is applied to a display device with a "COA structure", the counter substrate does not have a black matrix. Therefore, the light that is converted from "oblique light" and travels in the front direction by the overcoat film made of a low refractive index film and a high refractive index film is not blocked by the black matrix. As a result, when the technical idea of ​​this embodiment is applied to a display device with a "COA structure", a greater effect can be obtained in terms of improving the brightness in the front direction.

[0108] Within the scope of the concept of the present invention, a person skilled in the art may conceive of various modifications and alterations, and it is understood that such modifications and alterations also fall within the scope of the present invention. For example, those in which a person skilled in the art appropriately adds, deletes, or modifies the design of the above-mentioned embodiment, or adds, omits, or modifies the conditions of a process, are also included in the scope of the present invention as long as they include the gist of the present invention.

[0109] Furthermore, other effects and advantages brought about by the aspects described in the embodiments that are obvious from the description in this specification or that can be appropriately thought of by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0110] 1 LCD display device 2 Display Panel 3. Backlight 4 Optical sheets 5. Polarizing Plate 6 Polarizing Plate 10 Substrate 20 Substrate 30 Low refractive index film 30A Low refractive index film 30B Low refractive index film 40 High refractive index film 100A Organic Insulating Film 100B Organic insulating film 200A alignment film 200B alignment film 310 Titanium film 320 Aluminum Film 330 Titanium Film 340 ITO film 350 Molybdenum film CE Common electrode CFR Color Filter CFG Color Filter CFB Color Filter CH1 Contact hole CH2 Contact Hole CH3 Contact Hole CI Capacitive insulating film CT Controller DA display area DF Diffusion Sheet F Flexible board G scan line GD1 Scan Driver GD2 Scan Driver GE1 Gate electrode GE2 Gate electrode GP Gap IL1 Insulation layer IL2 Insulation layer IL3 Insulation layer IL4 Insulation Layer IL5 Insulation Layer IL6 Insulation Layer IL7 Insulation Layer LC liquid crystal layer LG light guide LS Light Emitting Element MA implementation area OC overcoat film OC1 overcoat film OR opening area OS semiconductor layer PE pixel electrode PLG1 Contact part PLG2 Contact part PLG3 Contact part PR1 Prism sheet PR2 Prism sheet PX pixels RE relay electrode S signal line SA Surrounding Areas SE source electrode SL Slit SP Spacer SPR subpixel SPG Subpixel SPB subpixel ST selector circuit SUB1 Array board SUB2 Opposite board SW Switching element T terminal section TML Conductive Film

Claims

1. an array substrate having switching elements; a counter substrate disposed opposite the array substrate; A display device comprising: The opposing substrate is A light-transmitting substrate; an overcoat film in contact with the substrate; Including, The display device, wherein the overcoat film is composed of a plurality of types of films having different refractive indices.

2. 2. The display device according to claim 1, The overcoat film is patterned.

3. 3. The display device according to claim 2, The overcoat film is A patterned first insulating film; A patterned second insulating film; A display device having the above configuration.

4. 4. The display device according to claim 3, The switching element has a gate electrode, the second insulating film is provided above the gate electrode, The second insulating film has a refractive index lower than that of the first insulating film.

5. 4. The display device according to claim 3, The second insulating film is A first surface in contact with the substrate; a second surface opposite the first surface; having A display device, wherein an area of ​​the second surface is larger than an area of ​​the first surface.

6. 2. The display device according to claim 1, The display device, wherein the array substrate is provided with a color filter.

7. 2. The display device according to claim 1, A display device, wherein a color filter is provided on the opposing substrate.

8. A counter substrate which is a component of a display device, The opposing substrate is A light-transmitting substrate; an overcoat film in contact with the substrate; Including, The overcoat film is composed of a plurality of types of films having different refractive indices.

9. 9. The counter substrate according to claim 8, The overcoat film is patterned.

10. 10. The counter substrate according to claim 9, The overcoat film is A patterned first insulating film; A patterned second insulating film; having The second insulating film has a refractive index lower than that of the first insulating film.

11. The counter substrate according to claim 10, The second insulating film is A first surface in contact with the substrate; a second surface opposite the first surface; having An opposing substrate, the second surface having an area larger than the first surface.

12. 9. The counter substrate according to claim 8, The counter substrate is provided with a color filter.

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