Color filter substrate and display device including the same

Abstract

To provide a display device with enhanced contrast and good visibility, while preventing a stray light influence on a neighboring pixel in the display device.SOLUTION: Display devices include such as a liquid crystal display device using a white light-emitting type LED at backlight, the one using an LED emitting light in red, green and blue, and the one using an organic EL. Each has a lamination of light scattering layers configured to uniformly scatter light from a light source, which involves a problem of an adverse effect by stray light on a neighboring pixel, deteriorating display characteristics. A color filter and a display device have a barrier wall at the light scattering layer so as to improve the display characteristics.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a color filter substrate used in a liquid crystal display device, an LED display device using mini-LEDs or micro-LEDs, an organic EL display device, etc., and further to a display device including the color filter substrate.

Background Art

[0002] A conventional liquid crystal display device is composed of a backlight unit (Backlight Unit) using a fluorescent tube as a light source, a liquid crystal layer that controls the display / non-display of display dots, and a backplane on which thin film transistors (TFTs) that drive the liquid crystal molecules of the liquid crystal layer are arranged.

[0003] In recent years, instead of the above-mentioned fluorescent tube, for example, a technology using a backlight (referred to as mini-LED) having a structure in which a plurality of white LED chips with a size of 50 μm to 200 μm are arranged in a matrix in a liquid crystal display device has attracted attention.

[0004] Since the light emission luminance of an LED chip can be individually adjusted, in a mini-LED, a liquid crystal display device that can perform finer brightness adjustment has been proposed by adopting a technology called local dimming in which a display screen is divided into a plurality of parts and a plurality of white LEDs included in the divided sections are turned on or off.

[0005] And a display device called micro-LED has been proposed as a display device that does not use liquid crystal. Although not clearly defined, it is mainly a device in which LED chips are arranged in a matrix region smaller than mini-LEDs. Also, the LED chips are approximately 2 μm to 50 μm in size, and display is performed by individually driving each LED chip.

[0006] Unlike the mini-LEDs described above, micro-LEDs can be broadly classified into methods such as full-colorization using three types of single-color light-emitting LED chips that emit red, green, and blue light, and methods that combine an LED chip that emits light in the wavelength range from blue to near-ultraviolet with a wavelength conversion layer. The method using single-color light-emitting LED chips can perform full-color display by using a wavelength conversion layer made of a material called quantum dots that absorbs ultraviolet light from blue LEDs that emit light in the near-ultraviolet region or UV-LEDs with emission wavelengths such as 365 nm or 385 nm and converts it into red, green, and blue wavelengths.

[0007] An organic EL display device is a display device that uses a light-emitting layer that emits light by the recombination of electrons and holes injected into an organic compound as a display functional layer. Its light-emitting method can be broadly classified into a method that uses three types of light-emitting layers that emit red, green, and blue light, and a method that spectrally divides white light created by the mixture of light in a plurality of wavelength bands obtained by a wavelength conversion layer into red, green, and blue light using a color filter.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] In a display device using liquid crystal, the linearity of the light emitted from the display functional layer toward the pixel aperture was not sufficiently obtained. Therefore, there was a problem that stray light (oblique emitted light) occurred with respect to adjacent pixels, resulting in a decrease in display contrast.

[0010] In the micro-LED method, as the pixel size is miniaturized, a decrease in display contrast due to stray light becomes a problem. Also, when the display device is used in a bright environment, a decrease in display contrast due to incident light entering the display device from the outside is also a problem.

[0011] Patent Document 1 discloses a reflective liquid crystal display device provided with a light scattering film. However, no solution to the contrast reduction due to stray light derived from the scattering film is explicitly shown for the components.

[0012] Patent Document 2 relates to a quantum dot display device in which a color conversion substance is provided inside the through holes of the partition walls and a color filter is further laminated. Similar to Patent Document 1, no technology related to suppressing contrast reduction is disclosed. Also, the seventh embodiment is an example including a liquid crystal element, but the light source of that example is an organic EL element common to all pixels and does not include local dimming technology from the viewpoint of reducing the number of light emitting elements. The configuration of the seventh embodiment is a configuration in which a phosphor substrate and a liquid crystal element are bonded together, and the display tends to become dark, and furthermore, moire is likely to occur due to the alignment error between the phosphor substrate and the liquid crystal element.

[0013] When Patent Document 3 is applied to a normal liquid crystal display device in which a liquid crystal layer and a color filter are close to or in contact with each other, it has a problem that the technical practicality can be greatly reduced. A phosphor layer that emits fluorescence with excitation light (for example, blue light or ultraviolet light from an LED or an organic EL) is disposed between the partition walls shown in claim 1 and FIG. 1 thereof. When the primary light from a light source such as an LED is wavelength-converted by a phosphor or quantum dots (becoming fluorescence as secondary light), the secondary light has various forms of emission angles and polarization states. In a liquid crystal display device, the polarization is aligned using a polarizing plate, and the direction of polarization is changed by 90 degrees in the liquid crystal layer to turn on and off the emitted light and adjust the brightness from white to black. However, the secondary light from the phosphor layer has its polarization disrupted as described above, resulting in a state where contrast cannot be ensured.

[0014] FIG. 9 shows a conventional example of a display device including a direct - type backlight unit 50 having a blue LED as a light - emitting element 51. In this conventional example, a liquid crystal panel 49 is illustrated as a display function portion above the direct - type backlight unit 50. The liquid crystal panel 49 has a color filter including a black matrix disposed thereon. To indicate pixel positions, pixels a, b, c, d, and e are schematically shown in the liquid crystal panel.

[0015] The direct - type backlight unit 50 includes a plurality of light - emitting elements, a diffusion plate 52, a wavelength - conversion sheet 53, and, for example, two orthogonal prism sheets 54 disposed above the arrangement of the light - emitting elements. The light - emitting elements are often arranged with a plurality of LED chips individually packaged in a metal housing. The wavelength - conversion sheet is for converting a part of the blue light emission of the light - emitting elements into red and green light to obtain three colors of red, green, and blue.

[0016] Generally, on the light - emitting portions of these LED chips, a phosphor or light - scattering particles are filled together with a silicone resin. Since the light emission of the LED is highly linear and is emitted near the center of the LED chip, one role of these phosphors and light - scattering particles is to cause light scattering for field - of - view expansion. However, in a configuration where such packaged LED chips are arranged in a backlight unit, the emitted light from the LED chips becomes scattered, and the contrast is reduced because the light is scattered before reaching the color filter provided in the pixel aperture. Thus, it is difficult to obtain a sufficient effect when applying local dimming.

[0017] Both the diffusion plate 52 and the wavelength - conversion sheet scatter light. For example, the emitted light of the c - LED (blue LED) located directly below the c pixel spills over not only to the c pixel but also to adjacent pixels such as a, b, d, and e in the vicinity, further reducing the effect of local dimming. Such a phenomenon is not limited to micro - LED displays, but also LED displays called micro - LEDs have a problem of contrast reduction due to such light scattering or stray light to adjacent pixels. The present application aims to provide an LED display with less contrast reduction due to stray light. [Means for Solving the Problem]

[0018] According to claim 1 of the present invention, there is provided a color filter substrate having a first transparent substrate, a color filter layer composed of a red filter, a green filter, and a blue filter on the first transparent substrate, a semi-transmissive film, a first partition wall, and a light scattering layer, wherein the first partition wall has a lattice shape and is made of a light-absorbing material. By using such a color filter substrate, stray light does not enter adjacent pixels, and the display contrast is improved.

[0019] According to claim 2 of the present invention, the semi-transmissive film contains either carbon or transparent fine particles, or both. By using the color filter substrate according to claim 1, stray light does not enter adjacent pixels, and the display contrast is improved.

[0020] According to claim 3 of the present invention, the light scattering layer is adjacent to the semi-transmissive film or the first partition wall. By using the color filter substrate according to claim 1, stray light does not enter adjacent pixels, and the display contrast is improved.

[0021] According to claim 4 of the present invention, the color filter substrate according to claim 1 has the light scattering layer, a second partition wall, and a transparent resin layer in this order. By using such a color filter substrate, stray light does not enter adjacent pixels, and the display contrast is improved.

[0022] According to claim 5 of the present invention, the film thickness of the first partition wall is 0.5 μm or more and 50 μm or less. By using the color filter substrate according to claim 1, stray light does not enter adjacent pixels, and the display contrast is improved.

[0023] According to claim 6 of the present invention, a display device characterized by bonding the surface of the color filter substrate according to claims 1 to 5 on which the color filter is formed and the surface of an optical module in which a plurality of light-emitting elements are disposed on one surface of a second transparent substrate so as to face each other has the effect that stray light does not enter adjacent pixels and the display contrast is improved.

[0024] According to claim 7 of the present invention, in the display device according to claim 6, a display device including at least a liquid crystal layer and an array substrate of thin film transistors for driving the liquid crystal layer between the first transparent substrate and the optical module has the effect that stray light does not enter adjacent pixels and the display contrast is improved.

[0025] According to claim 8 of the present invention, in the display device according to claims 6 and 7, wherein the light-emitting element is a light-emitting diode, stray light does not enter adjacent pixels and the display contrast is improved.

Effects of the Invention

[0026] According to the present invention, it is possible to provide a display device that suppresses the influence of stray light on adjacent pixels, improves the contrast, and has good visibility.

Brief Description of the Drawings

[0027]

Figure 1

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Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same or substantially the same functions and components are denoted by the same reference numerals, and the description thereof is omitted or simplified, or described only when necessary.

[0029] In each figure, for the purpose of enabling each component to be recognized on the drawing, the dimensions and ratios of each component are appropriately different from the actual ones. In the illustration, there may be exaggeration for the purpose of explanation, and the sizes and lengths of the illustrated components are not fixed. Also, if necessary, elements that are difficult to illustrate, such as the configuration of a thin-film transistor, etc., and the structure of a plurality of layers constituting a conductive layer, the illustration of wiring connections to a circuit section, switching elements (thin-film transistors), etc., and some of the illustrations are omitted.

[0030] In each of the embodiments described below, characteristic parts will be described, and for example, the description of parts that have no difference between the components used in a normal display device and the display device according to this embodiment will be omitted.

[0031] Ordinal numbers such as "first" and "second" for the first partition, second partition, first substrate, second substrate, third substrate, etc. are attached to avoid confusion of components and do not limit the quantity. Further, the matrix arrangement of light-emitting elements refers to an arrangement in which light-emitting units each including one or more light-emitting elements (LEDs) are arranged in a matrix at a certain pitch in a plan view. In the following description, a substrate on which light-emitting elements are arranged in a matrix, or a substrate on which light-emitting units are arranged in a matrix at a certain pitch may be referred to as an optical module. It is desirable to dispose a thin-film transistor for driving the light-emitting element or light-emitting unit on the substrate. When the display function layer is a liquid crystal layer, this optical module is called a direct-type backlight. The light-emitting unit may be surrounded by partitions in a lattice pattern in a plan view when used as a display device.

[0032] In an embodiment of the present invention, for the "display function layer" included in the display device, any of a plurality of light-emitting diode elements called LEDs (Light Emitting Diodes) or a liquid crystal layer can be used. LEDs, LED chips, and light-emitting diode elements may simply be referred to as light-emitting elements in the following description.

[0033] An LED is a light-emitting diode (Light Emitting Diode), and compounds such as aluminum gallium arsenide (AlGaAs), gallium arsenide phosphide (GaAsP), indium gallium nitride (InGaN) / gallium nitride (GaN) / aluminum gallium nitride (AlGaN), gallium phosphide (GaP), zinc selenide (ZnSe), and aluminum gallium indium phosphide (AlGaInP) are applied to the LED.

[0034] Three types of light-emitting elements (LEDs) that emit red light, green light, and blue light can be used. For blue light-emitting LEDs and ultraviolet light-emitting LEDs, gallium nitride (GaN) is mainly applied. In the case of mini-LEDs, for example, LED chips having a size of 50 μm to 200 μm can be used. In the case of micro-LEDs, for example, LED chips having a size of 2 μm to 50 μm can be used.

[0035] The structure of the LED chip may use a horizontal LED in which the n-side electrode and the p-side electrode are on the same side, but a vertical LED in which the n-side electrode and the p-side electrode are on different surfaces (opposite parallel surfaces) in the thickness direction of the LED can also be used. In the following description, the upper electrode and the lower electrode refer to either the n-side electrode or the p-side electrode of the vertical LED. The pixel openings of the first partition or the second partition, or some light-emitting elements (light-emitting diodes) overlap with the center lines at the center positions in plan view. The pixel opening of the first partition and the pixel opening of the second partition are in overlapping positions in plan view.

[0036] Hereinafter, a first embodiment of the present invention will be described. [Transparent substrate] As the material of the first transparent substrate 100 applicable to the display device of the present invention, a transparent substrate such as a glass substrate, a quartz substrate, a sapphire substrate, or a plastic substrate including a polyimide film can be used. The second transparent substrates 300 and 500 on which a plurality of light-emitting elements are arranged in a matrix may be the same as the material of the transparent substrate 100, but may also be a substrate colored black or other colors. The second transparent substrates 300 and 500 may be a sapphire substrate or a silicon substrate on which CMOS elements (such as transistors) are arranged. It may also be a silicon substrate on which an LED (light-emitting element) grown through a buffer layer is arranged. The mounting of the light-emitting element 24 (blue LED or purple LED) may be flip-chip mounting using a low-melting-point alloy, mounting using an anisotropic conductive film, or wire bonding using a gold wire or the like. A plurality of thin-film transistors for driving the light-emitting element or the liquid crystal layer can be arranged on the second transparent substrate.

[0037] [Partition] The first partition wall and the second partition wall (sometimes simply referred to as the partition wall) related to the present invention can be used by dispersing a black coloring material having a visible light absorption function such as carbon in a resin. The planar shape of the partition wall is substantially the same as that generally called a black matrix. However, the partition wall related to the present invention has the role of suppressing the incidence of stray light diffused from an LED light source such as oblique light into an unintended pixel opening, for example, the opening of an adjacent pixel. Therefore, it is called a "partition wall".

[0038] As will be described in the examples below, in order to propose a thick partition wall or a two-layer partition wall, the first partition wall related to the present invention does not need to have high light-shielding properties. In terms of optical density ΔOD, for example, a range of 2 or more and 3 or less is sufficient. By setting the concentration of the black coloring material to be low, for example, a first partition wall with a thickness of 10 μm or more can be obtained. An optical density of 4 or more may be used, but this will increase the process load such as exposure time. When the optical density is 1 or less, it is easy to visually recognize the reflection of external light from a reflective electrode such as aluminum (the electrode of the LED), which may lead to a deterioration in the image quality of the display device. The concentration of the black coloring material such as carbon and its film thickness can be set to the concentration of the black coloring material that can be set within the above optical density range.

[0039] The film thickness of the first partition wall as viewed from the normal direction of the first transparent substrate 100 can be 0.5 μm or more and 50 μm or less. When the structure of the first partition wall and the second partition wall is adopted as in Example 2 described below, the film thickness of each of these partition walls may be, for example, as thin as 0.5 μm or more and 2.5 μm or less. When there is only the first partition wall as in Example 1, in order to mitigate the adverse effects on adjacent pixels of stray light (for example, L1 and L2 in FIG. 5), it is desirable to form it with a thick film thickness of, for example, 2.5 μm or more and 50 μm or less.

[0040] As light-absorbing black pigments, in addition to carbon, carbon fibers, carbon nanotubes, carbon nanohorns, carbon nanobrushes, etc. can be applied. Furthermore, organic pigments such as blue pigments may be added. Metal oxides such as titanium black may also be added. Carbon-based materials such as carbon nanotubes, carbon nanohorns, graphene, and graphite with high thermal conductivity can be added.

[0041] The above features related to the partition walls are common to the first partition wall and the second partition wall. The first partition wall and the second partition wall are each in a lattice pattern in plan view, and they overlap with the center of the line width in the first direction (X direction) and the second direction (Y direction) respectively. In other words, the center positions of a plurality of pixel openings also overlap in plan view.

[0042] The color filter to be described later, for example, extends the stripe patterns of the red filter, green filter, and blue filter in the first direction (X direction) respectively and arranges them adjacent to each other in the first direction (X direction). At this time, by making the first partition wall into the lattice pattern as described above, the stray light influence on adjacent pixels in the first direction (X direction) and the second direction (Y direction) can be reduced and the display quality can be improved.

[0043] In the configuration of the color filter substrate of the present invention, on the first substrate, first, a color filter and a semi-transmissive film are disposed, and further, a first partition wall, and in a later embodiment, a second partition wall is further laminated. Therefore, the stray light influence on adjacent pixels is extremely small. The reason will be described in detail in a later embodiment.

[0044] [Color Filter] On the first transparent substrate 100, a color filter (red filter R, green filter G, blue filter B) and a first partition wall can be laminated in this order. The red filter R, green filter G, and blue filter B are respectively disposed in the pixel openings in plan view. However, the color filter and constituent members such as the semi-transmissive film 3 and the first partition wall 2 described later can be formed on the first transparent substrate 100 together. The color filter typified by the red filter R, green filter G, and blue filter B is formed of a dispersion of the following organic pigments in a resin such as acrylic.

[0045] As the red organic pigment applicable to the present invention, for example, red pigments such as C.I.Pigment Red 7, 14, 41, 48:2, 48:3, 48:4, 81:1, 81:2, 81:3, 81:4, 146, 168, 177, 178, 179, 184, 185, 187, 200, 202, 208, 210, 246, 254, 255, 264, 270, 272, 279 can be used. Yellow pigments or orange pigments can also be used in combination with the red filter R.

[0046] As the yellow organic pigment applicable to the present invention, C.I.Pigment Yellow1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 15, 16, 17, 18, 24, 31, 32, 34, 35, 35:1, 36, 36:1, 37, 37:1, 40, 42, 43, 53, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81, 83, 93, 94, 95, 97, 98, 100, 101, 104, 106, 108, 109, 110, 1, 14, 115, 116, 117, 118, 119, 120, 123, 126, 127, 128, 129, 147, 151, 152, 153, 154, 155, 156, 161, 162, 164, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 179, 180, 181, 182, 187, 188, 193, 194, 199, 198, 213, 214, etc. can be mentioned.

[0047] For green organic pigments, for example, green pigments such as C.I.Pigment Green7, 10, 36, 37, etc. can be used, and yellow pigments can also be used in combination. Halogenated zinc phthalocyanine green pigments and halogenated aluminum phthalocyanine green pigments can be preferably used.

[0048] For blue organic pigments, for example, blue pigments such as C.I.Pigment Blue15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 60, 64, etc. can be used, and purple pigments can also be used in combination. Examples of purple pigments include C.I.PigmentViolet1, 19, 23, 27, 29, 30, 32, 37, 40, 42, 50, etc.

[0049] These organic pigments are dispersed and used in a transparent resin together with an organic solvent and a dispersant. The transparent resin is desirably a transparent resin having a transmittance of 90% or more in the visible range, and desirably an alkali-soluble photosensitive resin containing a resin precursor. The pigment can be contained in the resin in the range of 15% to 45% by mass.

[0050] As the photosensitive resin, a (meth)acrylic compound or cinnamic acid having a reactive substituent such as an isocyanate group, an aldehyde group, or an epoxy group is reacted with a linear polymer having a reactive substituent such as a hydroxyl group, a carboxyl group, or an amino group, and a resin in which a photocrosslinkable group such as a (meth)acryloyl group or a styryl group is introduced into the linear polymer is used.

[0051] Examples of monomers and oligomers that are precursors of transparent resins include various acrylate esters and methacrylate esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, cyclohexyl (meth)acrylate, polyethylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tricyclodecanyl (meth)acrylate, melamine (meth)acrylate, epoxy (meth)acrylate, (meth)acrylic acid, styrene, vinyl acetate, (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, acrylonitrile, etc. These can be used alone or in combination of two or more. When curing by ultraviolet irradiation with a light wavelength of 365 nm or the like, a photoinitiator or the like is further added.

[0052] [Light Scattering Layer] As shown in FIG. 1, FIG. 2, etc., a light scattering layer 4 can be disposed on the color filter substrate according to the present invention. The light scattering layer 4 can basically be a dispersion of a transparent resin and transparent particles. Further, as will be described later, in order to suppress the incidence of scattered light to adjacent pixels, a light-absorbing black coloring material such as carbon can be added.

[0053] For the transparent particles, for example, transparent particles with an average particle size of 1 μm or more and 3.0 μm or less can be applied. Optically isotropic transparent particles can be used for the transparent particles. "Optically isotropic" means that the transparent particles applied to the embodiments of the present invention have a crystal structure with equal a-axis, b-axis, and c-axis, or are amorphous, and the propagation of light is isotropic without being affected by the crystal axis or crystal structure. Silica particles have an amorphous structure (amorphous).

[0054] As particles of resins such as resin beads, particles having various properties including refractive index are known, and these particles can be used in combination. Particles of resins such as acrylic, styrene, urethane, nylon, melamine, and benzoguanamine may be used in combination. For the light scattering layer 10 For example, it is preferable to use light-scattering particles (transparent particles) having a size in the micron range with an average particle diameter of 1.0 μm or more and 3.0 μm or less. That is, by using particles having a particle diameter larger than the wavelength of visible light, it is easy to obtain appropriate light-scattering properties for the light-scattering layer 4.

[0055] In addition, transparent fine particles with an average particle diameter of around 0.2 μm or 0.1 μm or less may be used in combination from the viewpoint of a dispersion aid. The above-mentioned transparent particles 8 or transparent fine particles can be dispersed in a transparent resin or a resin containing an ultraviolet absorber to form the light-scattering layer 10.

[0056] Transparent particles and transparent fine particles of zinc oxide that are transparent in the visible region and can absorb ultraviolet light of 390 nm or less can also be used. In the description of the present invention, particles with an average primary particle diameter of 1 μm or more are regarded as transparent particles, and particles with an average primary particle diameter of 0.2 μm or less are regarded as transparent fine particles.

[0057] The thickness of the light-scattering layer 4 is a dispersion of transparent particles larger than the wavelength of light, and in this relationship, it can be 2.5 μm or more and 50 μm or less. It can also be formed thicker than 50 μm, but the improvement in scattering properties by making it thicker than 50 μm is small. Rather, when forming it thick, it is easy to waste the process load, for example, the working time such as coating and drying. In the case of a light-scattering layer with a film thickness of less than 2.5 μm, and further less than 2.0 μm, it is difficult to obtain a sufficient scattering effect for visibility.

[0058] Light scattering does not necessarily have to be limited to the dispersion of transparent particles in a transparent resin. For example, by using a dispersion liquid in which two resins with different refractive indices are dissolved in an organic solvent or the like, and applying and drying it, phase separation of the two resins can be performed to impart light-scattering properties.

[0059] In a display device that does not use a circular polarizing plate or a polarizing plate, it is not necessary for the transparent particles to be optically isotropic, and the selection range of the transparent particles 8 can be widened. For example, zinc oxide particles can be used as the transparent particles that can be added to the light scattering layer 4. Zinc oxide has a high transmittance in the visible region from 400 nm to 700 nm and can absorb ultraviolet light of 390 nm or less. From this perspective, in a display device that does not use a circular polarizing plate, it is meaningful to use transparent particles of zinc oxide and transparent fine particles.

[0060] [Semi-transmissive film] The semi-transmissive film adjusts the transmittance for improving visibility, and plays a major role in suppressing external light reflection from the light scattering layer 4 and the wavelength conversion layer (in mini-LEDs using a liquid crystal layer, a wavelength conversion sheet is often used) to the viewing side when used as a display device. The semi-transmissive film can further suppress external light reflection from the interface with the first partition wall. In a display device provided with a reflective electrode such as a micro-LED, the semi-transmissive film can suppress external light reflection from the reflective electrode.

[0061] The semi-transmissive film is at least a dispersion of carbon and resin. An ultraviolet absorber may be added in addition to carbon. The semi-transmissive film is a resin dispersion containing carbon as the main pigment, and it is preferable that the transmittance of the semi-transmissive film for visible light is in the range of 70% or more and 99.7% or less. From the perspective of this transmittance, the addition amount of carbon to the resin dispersion is adjusted. In addition to carbon, transparent fine particles or organic pigments such as blue may be added. Adjustment of the transmittance of such a semi-transmissive film can be easily achieved by setting the addition amount of carbon, which is a black pigment, within a range of, for example, 0.2 wt% to 5 wt% with respect to the resin solid content. When the carbon addition amount exceeds 6 wt%, and further 7 wt%, the transmittance of the transmittance adjustment layer decreases too much.

[0062] Assuming external light incident on the display surface, the external light passes through the semi-transmissive film once, is then reflected by the light-reflective electrode, and then passes through the semi-transmissive film again and is emitted to the observer side. By passing through this light twice, external light reflection can be significantly reduced. If the visible light transmittance of the semi-transmissive film is 70% or more, the circular polarizing plate The display device provided by the present invention is brighter than the display device using [specific component]. In the display device of the present invention, a semi-transmissive film in a region with a high transmittance can be used, and a circular polarizing plate can also be used to form the display device.

[0063] Also, in many liquid crystal display devices, two polarizing plates (with orthogonal polarization axes) are used in a crossed Nicol configuration. When using such a circular polarizing plate or polarizing plate, for the purpose of improving dispersibility or reducing the refractive index of the semi-transmissive film, optically isotropic and transparent fine particles that do not cause polarization deviation can be added to the semi-transmissive film.

[0064] For example, when the semi-transmissive film is a transparent inorganic film or a resin film with a transmittance close to 100% of visible light, ripples due to interference may occur in the light reflection at the interface with the first partition wall, and the first partition wall may be slightly colored and observed. Such slight coloring due to reflected light is likely to be observed when the display of the display device is turned off for black display.

[0065] Also, in such cases, it may look iridescent when viewed from an oblique direction from the observer, and the visibility is likely to decrease.

[0066] On the other hand, by using silica fine particles and carbon in combination to form a semi-transmissive film, an effect of reducing the size of such ripples can be obtained. From the above viewpoints, a semi-transmissive film containing transparent fine particles in the visible region is useful. The same effect can be obtained even if silica fine particles are not included and low-concentration carbon is included.

[0067] The particle size of transparent particles such as silica fine particles is not specified, but for example, transparent particles with an average primary particle size of 3 nm to 100 nm can be applied. The film thickness of the semi-transmissive film is preferably in the range of 0.1 μm to 2 μm, for example, but a film thickness of 2 μm or more is also acceptable.

[0068] Incidentally, when the semi-transmissive film is formed using an organic pigment as the main pigment component without using carbon, the reflected light of external light at the interface with the first partition wall may appear yellowish. On the other hand, in the semi-transmissive film containing carbon as the main pigment component, the reflected light is almost flat and hardly colored. That the reflected light is flat means that in the visible range of the light wavelength from 400 nm to 700 nm, for example, in a small range such as 50 nm, there is no unevenness (fluctuation) with a transmittance of 2% or more, and a transmittance curve close to a straight line can be obtained.

[0069] In other words, when the range of the visible region from 400 nm to 700 nm is divided in 50 nm units, the magnitude of the reflectance variation (ripple) within that 50 nm unit can be made 1.0% or less. Also, in the range of the visible region of the light wavelength from 400 nm to 700 nm, the reflectance at the interface with the first partition wall can be within the range of 0.01% or more and 1.0% or less.

[0070] The reflectance variation (ripple) is the difference between the valleys of the reflectance spectral curve within the above-mentioned 50 nm unit of the reflectance measured in the visible range of the light wavelength from 400 nm to 700 nm, but as a simple evaluation, the value of the reflectance peak within the 50 nm unit may be used. In the latter simple evaluation, the value of the apparent reflectance variation is a larger value.

[0071] The reflectance here is the reflectance measured through the transparent substrate and the semi-transmissive film with the reflectance of the aluminum film as the reference (100%). The measurement can be easily performed using, for example, a microscopic spectrophotometer. Here, optically isotropic transparent fine particles play an important role in suppressing reflectance variation. For the purpose of further suppressing the effect of reflectance variation and reducing the reflectance, a semi-transmissive film containing a small amount of carbon and blue pigment in the resin together with the transparent particles may also be used.

[0072] In the color filter substrate configuration of the present invention, the semi-transmissive film 3 is a color filter (red filter It also serves as a planarization film for the red filter R, green filter G, and blue filter B. As described above, the semi-transmissive film 3 suppresses external light reflection from a light-scattering film or the like and improves visibility. In addition, it can also play a role in improving the flatness of the color filter. The flatness improvement of the semi-transmissive film 3 can be further enhanced by adding transparent particles such as the above-mentioned carbon or silica fine particles. Here, the average primary particle diameter of the transparent particles such as silica fine particles is preferably 100 nm or less as described above. When the average primary particle diameter greatly exceeds 100 nm, unevenness due to the particle diameter of the transparent particles tends to occur, which is likely to have an adverse effect.

Example

[0073] Example 1 will be described with reference to FIGS. 1, 3, 4, and 10. FIG. 1 is a cross-sectional view of a color filter substrate 110 according to the present invention. FIG. 3 is a partial plan view showing only the color filter (red filter R, green filter G, blue filter B). FIG. 4 is a partial plan view of FIG. 1 viewed from the Zo direction. In FIG. 4, the illustration of the light-scattering layer is omitted. FIG. 10 is a partial cross-sectional view of a conventional color filter configuration in which a red filter R', green filter G', and blue filter B' are laminated on a black matrix 10.

[0074] A semi-transmissive film 3, a light-scattering layer 3, a first partition wall, a transparent resin layer 11, etc. are laminated on a color filter 5 in which a red filter R, a green filter G, and a blue filter B are adjacent to each other. In Example 1, the light-scattering layer 3 is disposed so as to fill the space between the first partition walls having a thickness in the normal direction of the first transparent substrate 100. The transparent resin layer 11 may be omitted. The film thickness of each of the red filter R, green filter G, and blue filter B was, for example, 2.2 μm.

[0075] In the first embodiment, from the viewpoint of the particle size of the transparent particles, the film thickness of the first partition wall (in the direction normal to the first transparent substrate 100) is limited by the film thickness required for the light scattering layer 4. As described above, since the light scattering layer 4 has a thickness of 2.5 μm or more and 50 μm, it is desirable that the film thickness of the first partition wall in the first embodiment is 2.5 μm or more and 50 μm. (The film thickness of the first partition wall in the second embodiment described later may be formed to be as thin as 0.5 μm). The light scattering layer 4 can be formed, for example, by injecting a dispersion of transparent particles, a resin, and an organic solvent between the first partition walls using an inkjet or a micro needle.

[0076] The color filter 5 related to the configuration of the color filter substrate 110 of the present invention has an overlap of an overlapping portion Wrg between the red filter R and the green filter G, an overlapping portion Wgb between the green filter G and the blue filter B, and an overlapping portion Wbr between the blue filter B and the red filter, as shown in FIG. 3. The color filter configuration proposed in the present invention stacks color filters (red filter R, green filter G, blue filter B) directly on the first transparent substrate 100. At this time, the heights of the overlapping portion Wrg, the overlapping portion Wgb, and the overlapping portion Wbr are small irregularities that are approximately within the range of plus 0.4 μm to minus 0.5 μm. When the semi-transmissive film 3 is laminated on these color filters 5, the irregularities of the overlapping portions become smaller and are approximately within the range of plus 0.2 μm to minus 0.3 μm. As described above, the semi-transmissive film 3 has two effects of improving flatness in addition to the effect of suppressing external light reflection.

[0077] However, the unevenness of the overlapping portion of the conventional color filter in which the color filters (red filter R’, green filter G’, blue filter B’) are laminated on the black matrix 10 shown in FIG. 10 is quite large. The height H2 of the raised portion of each overlapping portion is quite large, for example, 1.7 μm for Wrg, 1.3 μm for Wbr, and 1.5 μm for Wbg. The reason for the large height H2 is that a black matrix 10 with a thickness (for example, 1.2 μm) is formed on the base of the color filter. Since the difference in unevenness of the overlapping portion is directly related to the variation and accuracy of the first partition wall laminated in the subsequent process, it can be determined that the proposed configuration of the present invention is excellent. The effects of the light scattering layer 4 and the thick first partition wall will be described in later embodiments.

[0078] Embodiment 2 will be described with reference to FIGS. 2, 3, 4, and 10. FIG. 2 is a cross-sectional view of a color filter substrate 210 according to the present invention. FIG. 3 is a partial plan view showing only the color filters (red filter R, green filter G, blue filter B). FIG. 4 is a partial plan view of FIG. 1 viewed from the Zo direction. In FIG. 4, the illustration of the light scattering layer is omitted. FIG. 10 is a partial cross-sectional view of a conventional color filter configuration in which a red filter R’, a green filter G’, and a blue filter B’ are laminated on a black matrix 10.

[0079] A semi-transmissive film 3, a first partition wall, a light scattering layer 4, a second partition wall 2, a transparent resin layer 11, etc. are laminated on a color filter 5 in which a red filter R, a green filter G, and a blue filter B are adjacent to each other. The major difference between Embodiment 1 and Embodiment 2 is that the light scattering layer 4 is a single-layer structure, and the second partition wall is laminated on this light scattering layer 4. By adopting a two-layer structure of the first partition wall and the second partition wall, the adverse effect of stray light on adjacent pixels can be further reduced.

[0080] Different from Embodiment 1, each of the first partition wall and the second partition wall of a thin film (for example, 1 μm) has the merit of being easily formed in a photolithography process, and the light scattering layer 4 related to Embodiment 2 has the merit of being easily formed by a common coating device such as a slit coater. The effects of the first partition wall, the light scattering layer 4, and the second partition wall 2 will be described in later embodiments.

[0081] Embodiment 3 is an embodiment of the display device according to Embodiment 2 of the present invention. Embodiment 3 will be described with reference to FIG. 5. FIG. 5 is a partial cross-sectional view of the display device according to the present invention, and is a display device 101 in which the color filter substrate 110 of Embodiment 1 and the array substrate 310 on which the light-emitting elements D1, D2, and D3 are disposed are bonded to face each other.

[0082] In the display device 101 shown in FIG. 5, the light-emitting units 38 divided by the third partition wall 33 are arranged in a matrix, and the light-emitting element D1 in the light-emitting unit 38 is driven by one or more thin-film transistors. The number of light-emitting elements in the light-emitting unit 38 divided by the third partition wall 33 may be one or more, and is not limited to one.

[0083] The light-emitting element D1 shown in FIG. 5 is located below the blue filter B (in the Z direction in the drawing) and is a blue-light-emitting LED (light-emitting diode). In order to improve the uniformity of the display screen and reduce unevenness, for example, a plurality of light-emitting elements with randomly changed angles of 90° each in plan view may be arranged in the light-emitting unit. Note that the light-emitting element D2 located below the red filter R is a red-light-emitting element, and the light-emitting element D3 located below the green filter G is a green-light-emitting LED.

[0084] The light emission from the light-emitting element D2 is indicated by the emitted light L1, L2, L3, L4, and L5. The obliquely emitted light L1 and L5 from the end of the light-emitting element D2 are cut by the thick first partition wall, and it is possible to suppress stray light from entering adjacent pixels. When the thickness of the first partition wall is thin, there is a high possibility that the obliquely incident light enters adjacent pixels.

[0085] The emitted light of an LED element without scattering particles or wavelength conversion particles filled inside the LED chip has high directivity and it is difficult to secure a wide viewing angle. The light scattering layer 4 shown in Fig. 5 has the effect of scattering the emitted light from the light emitting elements D1, D2, and D3 to expand the viewing angle. The main role of the semi-transmissive film 3 in this Example 3 is to suppress external light reflection of the light scattering layer 4 and to suppress external light reflection at the interface between the first partition wall and the semi-transmissive film 3. The LED chip used in the display device proposed in the present invention is preferably an LED chip without scattering particles or wavelength conversion particles filled inside. Fig. 5 shows an LED display (μLED) without a circular polarizing plate, but a circular polarizing plate may be attached to the surface on the viewing side of the display device as needed.

[0086] Example 4 will be described with reference to Figs. 6, 7, and 8. Fig. 6 is a partial cross-sectional view of a display device according to a second embodiment of the present invention. It is a liquid crystal display device (mini LED) in which the display function layer is liquid crystal 30. Fig. 7 is an enlarged view of part A in Fig. 6, including the first partition wall, the second partition wall 2, and the light scattering layer 4. Fig. 8 is an enlarged view of part B in Fig. 6, including a thin film transistor 60 for driving the light emitting element D5. In Example 4, the optical module 510 in which the light emitting elements are arranged serves as a direct-lit backlight unit and is driven by local dimming. In Fig. 8, only one thin film transistor 60 is shown, but there are two or more thin film transistors for driving one light emitting element (LED) or a set of light emitting units 39, which are not shown. When a gate signal is input to the gate electrode 56, the current from the power supply line 67 of the thin film transistor 60 enters the drain electrode 57 through the source electrode and the semiconductor layer 55, causing the light emitting element 70 to emit light.

[0087]

[0088] ​The lower electrode 74 of the light-emitting element 70 is electrically connected to the light-reflective reflective electrode 65 via a connection layer 75 made of a low-melting alloy containing indium or the like. The reflective electrode 65 is connected to the drain electrode 57 of the thin-film transistor 60 at the contact hole 66. As the connection layer 75, other connection means such as an anisotropic conductive film may be used. As the common electrode of the light-emitting element 70, a transparent conductive film such as ITO can be used. A metal thin film with good conductivity may be laminated as an auxiliary conductor on a part of the common electrode.

[0089] Three or more light-emitting elements D4, D5, and D6 are arranged in the light-emitting unit 39 and include a red light-emitting element, a green light-emitting element, and a blue light-emitting element. There are roughly two types of driving methods for the light-emitting elements. One is a local dimming method that makes the red light-emitting element, green light-emitting element, and blue light-emitting element emit light uniformly to emit white light and adjusts the brightness of the white light. The other is a method of driving with local dimming including adjusting the color tone by adjusting the light emission intensity of a specific light-emitting element. The orientation angle, density, and number of the light-emitting elements can be adjusted so that there is no light emission unevenness.

[0090] The two-layer partition walls shown in FIG. 7, the first partition wall and the second partition wall 2, play the role of improving the contrast by suppressing stray light, similar to the thick first partition wall shown in Example 3. In other words, the oblique light 44 and 45 from a light source such as an LED can be cut by the second partition wall to reduce the adverse effect on adjacent pixels.

[0091] In addition to transparent particles, it is desirable to add a light-absorbing black coloring material such as carbon to the light-scattering layer 4. The addition amount of the black coloring material can be, for example, 0.2 at% or more and 5 at% or less in terms of the resin solid ratio (weight ratio). The addition of such a black coloring material can suppress the diffused light crossing the light-scattering film 4 in FIG. 7 in the direction of adjacent pixels, and can suppress a decrease in contrast and a decrease in color purity. At this time, it is preferable that the partition wall width (common to the first partition wall and the second partition wall 2) Tw is twice or more the thickness Th of the light-scattering layer 4. The suppression effect can be expected from the square of the ratio of the light-scattering layer Th to the partition wall width Tw. When the black coloring material is carbon, coloring of the light 41 emitted to the pixel opening can be avoided.

[0092] The display device including the color filter substrate according to the above-described embodiment can be applied in various ways. Examples of electronic devices to which the display device according to the above-described embodiment can be applied include mobile phones, portable game devices, portable information terminals, personal computers, electronic books, video cameras, digital still cameras, head-mounted displays, navigation systems, audio playback devices (such as car audio and digital audio players), copiers, facsimiles, printers, printer multifunction devices, vending machines, automated teller machines (ATMs), personal authentication devices, optical communication devices, electronic devices such as IC cards, and the like. Each of the above embodiments can be freely combined and used. It is desirable that the electronic device equipped with the display device according to the embodiment of the present invention further includes an antenna for communication and non-contact power reception and power supply.

[0093] Although the preferred embodiments of the present invention have been described above, it should be understood that these are merely exemplary of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other changes can be made without departing from the scope of the present invention. Therefore, the present invention should not be regarded as being limited by the foregoing description, but rather is defined by the scope of the claims.

Industrial Applicability

[0094] The present invention can be used in semiconductor devices including a wiring substrate and a wiring substrate on which a semiconductor element is mounted.

Explanation of Reference Numerals

[0095] 1, 6: First partition wall 2: Second partition wall 3: Semitransparent film 4: Light scattering layer 5: Color filter 8: Pixel electrode 9: Common electrode 10: Black matrix 11: Transparent resin layer 12: Adhesive layer 17: First insulating layer 18: Second insulating layer 19: Third insulating layer 23: Light control sheet (prism sheet) 24: Wavelength conversion layer 25, 26: Polarizing plate 30: Liquid crystal layer 33, 37: Third partition wall 38, 39: Light emitting unit 41: Linear light 44, 45: Oblique light 49: Liquid crystal panel 50: Backlight unit 51: Light emitting element (LED filled with scattering particles) 52: Diffusion plate 53: Wavelength conversion sheet 54: Prism sheet 55: Semiconductor layer 56: Gate electrode 57: Drain electrode 58: Source electrode 59: Light shielding film 60: Thin film transistor 61: Fourth insulating layer 62: Fifth insulating layer 63: Sixth insulating layer 64: Gate insulating film 65: Reflective electrode 66: Contact hole 67: Power supply line 69: Upper electrode (common electrode) 70: Light emitting element (LED) 71: First semiconductor layer 72: Light emitting layer 73: Second semiconductor layer 74: Lower electrode 75: Connection layer 100, 200: First transparent substrate 110, 210: Color filter substrate 101, 102: Display device 300, 500: Second transparent substrate 310, 510: Light module (with light emitting elements arranged) 400: Third transparent substrate Array substrate (on which thin film transistors for driving liquid crystal are disposed) D1, D2, D3, D4, D5, D6 ··· Light emitting elements (LEDs) R, R’: Red filter G, G’: Green filter B, B’: Blue filter

Claims

1. A color filter substrate having, in this order, a first transparent substrate, a color filter layer composed of a red filter, a green filter, and a blue filter on the first transparent substrate, a semi-transmissive film, a first partition wall, a light scattering layer, a second partition wall, and a transparent resin layer, wherein the first partition wall and the second partition wall are in a lattice shape in which the openings thereof overlap each other in plan view and are made of a light-absorbing material, and the partition wall widths of the first partition wall and the second partition wall are at least twice the thickness of the light scattering layer. A color filter substrate characterized by this.

2. The color filter substrate according to claim 1, wherein the semi-transmissive film contains either carbon or transparent fine particles, or both.

3. The color filter substrate according to claim 1, wherein the light scattering layer is adjacent to the semi-transmissive film or the first partition wall.

4. The color filter substrate according to claim 1, wherein the film thickness of the first partition wall is 0.5 μm or more and 50 μm or less.

5. A display device, characterized in that the surface on which the color filter of the color filter substrate according to any one of claims 1 to 4 is formed and the surface of a light module in which a plurality of light-emitting elements are arranged on one surface of a second transparent substrate are bonded to face each other.

6. In the display device according to claim 5, a display device including at least a liquid crystal layer and an array substrate of thin film transistors for driving the liquid crystal layer between the first transparent substrate and the light module.

7. The display device according to claim 5 or 6, wherein the light-emitting element is a light-emitting diode.

Images