Wavelength conversion substrate

Abstract

This technology can contribute to improving the display performance of a display device equipped with a wavelength conversion layer containing quantum dots. [Solution] The wavelength conversion substrate 3A comprises a transparent substrate having a first main surface and a second main surface, a resin layer 34 provided on the first main surface and having a plurality of through holes, each of which has a shape extending in a first direction parallel to the first main surface, and a plurality of filling layers 36 that fill each of the plurality of through holes, each of which is a wavelength conversion layer containing quantum dots, and each of the wavelength conversion layers has a plurality of protrusions P on its surface that are parallel to the first main surface and extend in a second direction intersecting the first direction, and are arranged in the first direction, and the plurality of protrusions P create an inclined region on the surface.

Description

Technical Field

[0001] The present invention relates to a wavelength conversion substrate.

Background Art

[0002] In recent years, there has been a strong demand to improve color reproducibility in order to obtain higher-definition images in various display devices, from large and medium-sized display devices to small display devices such as those for smartphones. As one means of improving color reproducibility, for example, as shown in Patent Documents 1 and 2 below, the use of quantum dots has been studied.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a technology that can contribute to improving the display performance of a display device including a wavelength conversion layer containing quantum dots.

Means for Solving the Problems

[0005] According to one aspect of the present invention, a wavelength conversion substrate is provided comprising: a transparent substrate having a first main surface and a second main surface; a resin layer provided on the first main surface and having a plurality of through holes, each of which has a shape extending in a first direction parallel to the first main surface; and a plurality of filling layers that fill each of the plurality of through holes, each of which is a wavelength conversion layer containing quantum dots, wherein each of the wavelength conversion layers extends in a second direction parallel to the first main surface and intersecting the first direction, and has a plurality of convex portions on its surface that are arranged in the first direction, and the plurality of convex portions create a sloped region on the surface.

[0006] According to another aspect of the present invention, a wavelength conversion substrate is provided in which each of the plurality of protrusions has a height at the central portion that is higher than the height at both ends in the second direction.

[0007] According to yet another aspect of the present invention, a wavelength conversion substrate is provided relating to any of the above aspects, wherein the pitch T of the arrangement of the plurality of protrusions in the first direction is within the range of 10 μm to 50 μm.

[0008] According to yet another aspect of the present invention, a wavelength conversion substrate is provided relating to any of the above aspects, wherein the ratio H / T of the height H of the plurality of protrusions to the pitch T of the arrangement of the plurality of protrusions in the first direction is within the range of 0.05 or more and 0.5 or less.

[0009] According to yet another aspect of the present invention, a wavelength conversion substrate is provided in which each of the plurality of through holes has a ratio L / W of the aperture diameter L in the length direction to the aperture diameter W in the width direction, which is in the range of 1.1 to 5.

[0010] According to yet another aspect of the present invention, a wavelength conversion substrate is provided relating to any of the above aspects, wherein the height H of the plurality of protrusions is within the range of 10% to 15% of the thickness of the resin layer.

[0011] According to yet another aspect of the present invention, a wavelength conversion substrate is provided relating to any of the above aspects, wherein the volume of each of the plurality of packed layers is within the range of 1 to 1.3 times the volume of each of the plurality of through holes.

[0012] According to yet another aspect of the present invention, a display device is provided comprising a wavelength conversion substrate according to any of the above aspects and a dimming device installed facing the first main surface.

[0013] According to yet another aspect of the present invention, the dimming device is provided as a display device according to any of the above aspects, comprising a substrate and a plurality of light-emitting diodes arranged on the substrate corresponding to the plurality of through holes. [Effects of the Invention]

[0014] The present invention provides a technology that can contribute to improving the display performance of a display device equipped with a wavelength conversion layer containing quantum dots. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a cross-sectional view of a display device according to the first embodiment of the present invention. [Figure 2] Figure 2 is a top view of the wavelength conversion substrate included in the display device shown in Figure 1. [Figure 3] Figure 3 is a top view showing an enlarged portion of the wavelength conversion substrate shown in Figure 2. [Figure 4] Figure 4 is a cross-sectional view of the wavelength conversion substrate shown in Figure 3 along the IV-IV line. [Figure 5] Figure 5 is an enlarged top view showing a portion of the wavelength conversion substrate included in the display device according to the second embodiment of the present invention. [Figure 6] Figure 6 is a cross-sectional view of the wavelength conversion substrate shown in Figure 5 along the VI-VI line. [Modes for carrying out the invention]

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are more specific implementations of any of the above aspects. The matters described below can be incorporated into each of the above aspects either alone or in combination.

[0017] In addition, the embodiments shown below illustrate configurations for embodying the technical idea of the present invention, and the technical idea of the present invention is not limited by the materials, shapes, structures, etc. of the following constituent members. Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims described in the claims.

[0018] For elements having the same or similar functions, the same reference numerals are given in the drawings referred to below, and redundant descriptions are omitted. Also, the drawings are schematic, and the relationship between dimensions in one direction and dimensions in another direction, and the relationship between the dimensions of one member and the dimensions of other members, etc. may differ from the actual ones.

[0019] <1>First Embodiment FIG. 1 is a cross-sectional view of a display device according to a first embodiment of the present invention. FIG. 2 is a top view of a wavelength conversion substrate included in the display device of FIG. 1. FIG. 3 is a top view showing an enlarged part of the wavelength conversion substrate of FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV of the wavelength conversion substrate shown in FIG. 3.

[0020] In FIGS. 1 to 4, the X direction and the Y direction are directions parallel to the display surface of the display device 1A and intersecting each other. According to an example, the X direction and the Y direction are perpendicular to each other. The Z direction is a direction perpendicular to the X direction and the Y direction. That is, the Z direction is the thickness direction of the display device 1A.

[0021] Also, in FIGS. 3 and 4 and FIGS. 5 and 6 referred to later, an inorganic barrier layer 37 described later is omitted. And in FIG. 3, a portion of the surface of the filling layer 36 having the same height is shown by a broken line or a one-dot chain line. That is, in FIG. 3, contour lines are drawn over the filling layer 36.

[0022] The display device 1A shown in Figure 1 is a microLED display capable of color display using an active matrix driving method, in which each subpixel contains a light-emitting diode (LED). The display device 1A includes a dimming device 2, a wavelength conversion substrate 3A, and an adhesive layer 4.

[0023] The dimming device 2 emits light toward the wavelength conversion substrate 3A and is capable of adjusting at least one of the intensity of this light and the duration of light emission for each pixel or sub-pixel. The dimming device 2 includes a substrate 21, a multilayer wiring layer 22, and a light-emitting diode 23.

[0024] The substrate 21 includes, for example, an insulating substrate such as a glass substrate. The substrate 21 may further include an undercoat layer provided on the main surface of the insulating substrate facing the wavelength conversion substrate 3A. The undercoat layer is, for example, a laminate of silicon nitride layers and silicon oxide layers sequentially stacked on the insulating substrate. The substrate 21 may also be a semiconductor substrate such as a silicon substrate. The substrate 21 may be rigid or flexible.

[0025] The multilayer wiring layer 22 is provided on the main surface of the substrate 21 facing the wavelength conversion substrate 3A. The multilayer wiring layer 22 includes video signal lines, a first power line, a second power line, a scanning signal line, a pixel circuit, and an interlayer insulating film.

[0026] The video signal lines each extend in the Y direction and are arranged in the X direction. The scan signal lines each extend in the X direction and are arranged in the Y direction. The first and second power lines each extend in the Y direction and are arranged in the X direction, corresponding to the video signal lines. The first and second power lines may each extend in the X direction and be arranged in the Y direction, corresponding to the scan signal lines. Alternatively, one of the first and second power lines may each extend in the Y direction and be arranged in the X direction, corresponding to the video signal lines, while the other of them may each extend in the X direction and be arranged in the Y direction, corresponding to the scan signal lines.

[0027] The pixel circuits are arranged in the X and Y directions on the main surface of the substrate 21. Each pixel circuit includes a drive control element, a switch, and a capacitor. The drive control element is, for example, a p-channel field-effect transistor with its source connected to a first power line. The switch is, for example, an n-channel field-effect transistor with its gate connected to a scan signal line, its source connected to a video signal line, and its drain connected to the gate of the drive control element. The capacitor is, for example, a thin-film capacitor with one electrode connected to the gate of the drive control element and the other electrode connected to the first power line. The pixel circuits may have other configurations.

[0028] The light-emitting diode 23 has a multilayer structure. Here, the stacking direction of the layers contained in the light-emitting diode 23 is the Z direction. This stacking direction may be perpendicular to the Z direction.

[0029] The light-emitting diodes 23 have identical emission spectra. The light-emitting diodes 23 emit short-wavelength light, such as blue light and ultraviolet light. Here, as an example, we assume that the light-emitting diodes 23 are blue light-emitting diodes that emit blue light.

[0030] The light-emitting diodes 23 are arranged on the multilayer wiring layer 22 in accordance with the pixel circuit. Each of the light-emitting diodes 23 has its anode connected to the drain of the drive control element and its cathode connected to the second power line.

[0031] The wavelength conversion substrate 3A faces the dimming device 2. Specifically, the wavelength conversion substrate 3A faces the substrate 21 with the light-emitting diode 23 and the like in between.

[0032] The wavelength conversion substrate 3A includes a transparent substrate 31, a black matrix 32, a color filter 33 including a first color layer 33R, a second color layer 33G, and a base layer 33B, a resin layer 34, an inorganic coating layer 35, filling layers 36R, 36G, and 36B, and an inorganic barrier layer 37.

[0033] The transparent substrate 31 is transparent to visible light. The transparent substrate 31 is, for example, a colorless substrate. The transparent substrate 31 may have a single-layer structure or a multilayer structure. The transparent substrate 31 is made of, for example, glass, transparent resin, or a combination thereof. The transparent substrate 31 may be rigid or flexible. The transparent substrate 31 has a first main surface facing the dimming device 2 and a second main surface which is the back surface of the first main surface.

[0034] The black matrix 32 is provided on the first main surface of the transparent substrate 31. The black matrix 32 is a black layer that blocks visible light. The black matrix 32 constitutes a part of the resin-containing layer.

[0035] The black matrix 32 consists of, for example, a mixture containing a binder resin and a colorant. The colorant is, for example, a black pigment, or a mixture of pigments that produce black by subtractive color mixing, such as a mixture containing blue pigment, green pigment, and red pigment.

[0036] The black matrix 32 has second through-holes at the locations of the light-emitting diodes 23. The opening on the transparent substrate 31 side of each second through-hole is larger in the direction perpendicular to the Z direction compared to the light-emitting diodes 23.

[0037] Here, the second through-holes are arranged in a first and second direction that intersect each other. The first and second directions are the Y and X directions, respectively. Each of the second through-holes has a shape that extends in the first direction.

[0038] The first colored layer 33R, the second colored layer 33G, and the base layer 33B form a stripe arrangement on the transparent substrate 31 on which the black matrix 32 is provided. These form multiple pixels, each composed of the first colored layer 33R, the second colored layer 33G, and the base layer 33B, and these pixels are arranged in the X and Y directions. The first colored layer 33R, the second colored layer 33G, and the base layer 33B constitute a color filter 33. The color filter 33 also constitutes another part of the resin-containing layer.

[0039] As described above, the first colored layer 33R is a red colored layer, and the second colored layer 33G is a green colored layer. The base layer 33B is a colorless light-transmitting layer or a blue colored layer. Each of the first colored layers 33R fills one of the second through-holes. Each of the second colored layers 33G fills another of the second through-holes. Each of the base layers 33B fills yet another of the second through-holes.

[0040] The resin layer 34 is provided on a composite film consisting of a first colored layer 33R, a second colored layer 33G, and a base layer 33B. In one example, the resin layer 34 is transparent. In this case, the resin layer 34 may be colored or colorless. The resin layer 34 may have light-scattering properties.

[0041] The resin layer 34 is made of, for example, an acrylic resin, a siloxane resin, an epoxy resin, a polyimide resin, or two or more cured products thereof. From the viewpoint of adhesion with the inorganic barrier layer 37, it is preferable that the resin layer 34 does not contain a fluorine compound.

[0042] The resin layer 34 is a partition layer having first through-holes at the positions of the second through-holes. Here, the first through-holes are arranged in a first direction and a second direction that intersect each other, corresponding to the second through-holes. As mentioned above, the first direction and the second direction are the Y direction and the X direction, respectively. Each of the first through-holes has a shape that extends in the first direction. For example, the contour of the orthogonal projection of each of the first through-holes onto the first main surface of the opening on the transparent substrate 31 side (hereinafter referred to as the first contour) is approximately rectangular.

[0043] Furthermore, in the first through-hole, the first contour is provided such that it surrounds the contour of the orthogonal projection of the second through-hole onto the first main surface (hereinafter referred to as the second contour). The first contour does not necessarily have to surround the second contour. In a structure where the first contour surrounds the second contour, the effect of stray light on the display is smaller compared to a structure where the first contour does not surround the second contour.

[0044] For each of the first through-holes, the ratio L / W of the opening diameter L in the longitudinal direction to the opening diameter W in the width direction is preferably within the range of 1.1 to 5, and more preferably within the range of 1.2 to 4. The opening diameter of the first through-hole is the diameter of the opening on the dimming device 2 side of the opening of the first through-hole.

[0045] The portion of the resin layer 34 sandwiched between adjacent first through holes has a rectangular cross-sectional shape. This portion may have a forward tapered cross-sectional shape, an inverse tapered cross-sectional shape, or any other cross-sectional shape.

[0046] The inorganic coating layer 35 covers each side wall of the first through-hole and the upper surface of the resin layer 34. The inorganic coating layer 35 is open at the location of the first through-hole. Together with the resin layer 34, the inorganic coating layer 35 constitutes a partition wall having a through-hole at the location of the first through-hole.

[0047] The inorganic coating layer 35 may have a single-layer structure or a multi-layer structure. The layers included in the inorganic coating layer 35 are, for example, layers made of metal, alloy, or transparent dielectric. The metal or alloy is, for example, aluminum, titanium, chromium, neodymium, or an alloy containing one or more of these.

[0048] The inorganic coating layer 35 can be formed by vapor deposition methods such as sputtering. Furthermore, the openings in the inorganic coating layer 35 can be formed, for example, by etching.

[0049] The inorganic coating layer 35 can function as a reflective layer. In one example, the inorganic coating layer 35 has a reflectivity of 70% or more across the entire visible light range, and in another example, it is in the range of 70% to 98%. Here, the visible light range is defined as the wavelength range of 400 nm to 700 nm.

[0050] Furthermore, the inorganic coating layer 35, together with the inorganic barrier layer 37, can play a role in suppressing the degradation of the wavelength conversion layer containing quantum dots due to moisture. The thickness of the inorganic coating layer 35 is preferably in the range of 100 nm to 300 nm. For example, the inorganic coating layer 35 has a water vapor transmission rate of 10 as defined in JIS K7129:2019. -2 g / m 2 It is less than or equal to / day.

[0051] The packed layer 36R is provided on the first colored layer 33R. The packed layer 36R is a first wavelength conversion layer containing quantum dots and transparent resin. Here, the packed layer 36R converts the blue light emitted by the light-emitting diode 23 into red light.

[0052] The packed layer 36G is provided on the second colored layer 33G. The packed layer 36G is a second wavelength conversion layer containing quantum dots and transparent resin. Here, the packed layer 36G converts the blue light emitted by the light-emitting diode 23 into green light.

[0053] The filling layer 36B is provided on the base layer 33B. As described above, the filling layer 36B here is a colorless and transparent layer. In this case, the filling layer 36B is made of, for example, a transparent resin.

[0054] If the light-emitting diode 23 is an ultraviolet light-emitting diode, the packed layer 36B is a third-wavelength conversion layer. The third-wavelength conversion layer is a layer containing quantum dots and transparent resin. The third-wavelength conversion layer converts, for example, the ultraviolet light emitted by the ultraviolet light-emitting diode into blue light. In this case, packed layers 36R and 36G convert the ultraviolet light emitted by the ultraviolet light-emitting diode into red light and green light, respectively.

[0055] Of these packed layers, at least a portion of the wavelength conversion layer containing quantum dots has a surface irregularity structure, as described later, for packed layer 36. Preferably, all of the wavelength conversion layer has this irregularity structure on its surface. Packed layers that do not contain quantum dots may or may not have the above-mentioned irregularity structure on their surface.

[0056] The packed layer 36 shown in Figures 3 and 4 has a surface with multiple protrusions P that extend in a second direction parallel to the first main surface and intersecting the first direction, and are arranged in the first direction. Here, the surface of the packed layer 36 has multiple protrusions P that extend in the X direction and are arranged in the Y direction.

[0057] Each of the protrusions P has a substantially constant dimension in the Y direction, i.e., width. Each of the protrusions P has the greatest height at the midpoint in the width direction, and its height decreases toward both sides. Each of the protrusions P extends from one side wall parallel to the Y direction to the other side wall parallel to the Y direction of the through-hole provided in the partition wall.

[0058] Adjacent convex portions P in the Y direction are spaced apart from each other with a concave portion R in between. Each convex portion P creates a sloped region on the surface of the packing layer 36 that extends in the X direction and is inclined with respect to the Y direction, at a position between the top of the convex portion P and the bottom of the concave portions R located on either side of it. These sloped regions can play a role in focusing or diffusing the light emitted by the light-emitting diode 23.

[0059] The pitch T of the arrangement of the protrusions P in the first direction, in this case the Y direction, is preferably in the range of 10 μm to 50 μm, and more preferably in the range of 15 μm to 30 μm. It is difficult to produce a surface with high shape accuracy when the pitch T is small. If the pitch T is large, it becomes difficult to produce a surface with a large ratio H / T, which will be described later.

[0060] The position of the top of the protrusion P may be lower than the upper surface of the resin layer 34, equal to the upper surface of the resin layer 34, or higher than the upper surface of the resin layer 34. When the position of the top of the protrusion P is higher than the upper surface of the resin layer 34, the volume of the packing layer 36 can be set to, for example, a range of 1 to 1.3 times the volume of the first through-hole provided in the resin layer 34. If the packing layer 36 is a wavelength conversion layer, increasing its volume can increase the wavelength conversion efficiency.

[0061] The ratio H / T of the height H of the protrusion P to the pitch T is preferably in the range of 0.05 to 0.5, and more preferably in the range of 0.1 to 0.3. Increasing the ratio H / T increases the light-gathering or diffusion effect of the inclined surface. However, it is difficult to produce a bumpy structure with a large ratio H / T with high shape accuracy. The height H of the protrusion P is preferably in the range of 10% to 15% of the thickness of the resin layer 34. The height H of the protrusion P is the height of the top of the protrusion P relative to the bottom of the recess R, i.e., the lowest part of the surface of the filling layer 36.

[0062] Each of the filling layers can be formed by printing using ink. For example, inkjet printing can be used for this printing.

[0063] When forming a wavelength conversion layer as a packing layer, the above-mentioned ink can include, for example, quantum dots, (meth)acrylate, monofunctional and / or polyfunctional thiols, a photopolymerization initiator, and a solvent or dispersion medium. When forming a non-wavelength conversion layer that does not contain quantum dots as a packing layer, the above-mentioned ink can include, for example, (meth)acrylate, monofunctional and / or polyfunctional thiols, a photopolymerization initiator, and a solvent or dispersion medium. When such an ink is used, the coating film formed by printing can be cured by light irradiation.

[0064] Quantum dots are semiconductor particles that, for example, have a core-shell structure and have a particle diameter in the range of a few nanometers to about 10 nanometers.

[0065] The core consists of a semiconductor responsible for light emission. The emission spectrum of a quantum dot changes by changing the type of semiconductor that makes up the core and the particle size of the core.

[0066] The shell is a thin layer epitaxially grown on the surface of the core, having a thickness of 1 to 4 atoms. The shell contributes to improving and stabilizing the luminescence efficiency. The shell may have a single-layer structure or a multi-layer structure.

[0067] One example of a quantum dot is a structure in which a core made of InP is covered with a first shell made of ZnSe, and this is then covered with a second shell made of ZnS. Such quantum dots emit red light when the particle size is large, and green light when the particle size is small.

[0068] Another example of a quantum dot has a structure in which a core made of ZnSeTe is covered with a first shell made of ZnSe, and this is then covered with a second shell made of ZnS. Such quantum dots emit blue light when the particle size is small.

[0069] Quantum dots may have ligands on the surface of their core-shell particles. The ligands are hydrocarbons with functional groups that contribute to improved resistance and prevention of aggregation in dispersions. However, the ligands may be at least partially absent in the display device 1A.

[0070] The proportion of quantum dots in the total of quantum dots, (meth)acrylates, and monofunctional and / or polyfunctional thiols is preferably in the range of 5% by mass or more and 70% by mass or less, and more preferably in the range of 10% by mass or more and 60% by mass or less.

[0071] (Meth)acrylates are monofunctional, difunctional, or trifunctional (meth)acrylate monomers. Here, "(meth)acrylate" is a general term for both acrylates and methacrylates, and "(meth)acryloyl" is a general term for both acryloyl and methacryloyl. Examples of (meth)acrylates include 1,6-hexanediol diacrylate, nonylphenylcarbitol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-ethylhexylcarbitol acrylate, 2-hydroxyethyl acrylate, N-vinylpyrrolidone, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, bis(acryloyloxyethyl) ether of bisphenol A, and 3-methylpentanediol di(meth)acrylate. You may use trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, propoxylated dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, or two or more of these.

[0072] Examples of monofunctional and / or polyfunctional thiols include 1-dodecanethiol, ethanedithiol, mercaptopropionic acid, 1-hexanethiol, isoamyl mercaptan, 2-ethyl-hexanethiol, 1-octanthiol, 2-methyl-1-butanethiol, 2-ethylhexyl 3-mercaptopropionic acid, bis(3-mercaptopropionic acid)tetraethylene glycol, bis(3-mercaptopropanoic acid)2-[[3-(3-mercapto-1-oxopropoxy)-2,2-bis[(3-mercapto-1-oxopropoxy)methyl]propoxy]methyl]-2-[(3-mercapto-1-oxopropoxy)methyl]-1,3-propanediyl, trimethylolpropane Tris(3-mercaptopropionate), 2-ethylhexyl 3-mercaptopropionate, hexakis(3-mercaptopropionate)dipentaerythritol, or two or more of these can be used.

[0073] The proportion of monofunctional and / or polyfunctional thiols in the total of (meth)acrylate and monofunctional and / or polyfunctional thiols is preferably in the range of 0% by mass or more and 90% by mass or less, and more preferably in the range of 5% by mass or more and 30% by mass or less.

[0074] The above ink may further contain other components, such as scattering particles and dispersants.

[0075] The ink preferably has a viscosity at 23°C in the range of 8 mPa·s to 25 mPa·s. When the first to third wavelength conversion layers are formed by inkjet printing, an ink having the above viscosity is advantageous in achieving high ejection stability. The viscosity of the ink can be adjusted, for example, by the type and amount of solvent or dispersion medium and monomer.

[0076] A filling layer 36 having protrusions P on its surface can be formed, for example, by the following method. First, a first layer made of the above-mentioned ink is formed on the upper surface of the color filter 33 in the area corresponding to the protrusions P. That is, the first layer is formed in a stripe pattern on the upper surface of the color filter 33 at the location of the through-holes in the partition wall. Next, the first layer is cured or partially cured. Then, a second layer made of the above-mentioned ink is formed inside the through-holes in the partition wall. The second layer is formed thinly, for example, such that the height of the upper surface at the location of the gaps in the stripe pattern formed by the first layer is lower than the height of the upper surface of the first layer. After that, the second layer is cured. If the first layer is partially cured, the first layer is fully cured when the second layer is cured. In this way, a filling layer 36 having protrusions P on its surface is obtained.

[0077] The filling layer 36 having protrusions P on its surface can also be formed by other methods. When an ink droplet lands on the color filter 33, the ink spreads from the landing position and eventually forms a continuous film. If an ink with sufficiently high viscosity is used as the ink, and inkjet printing is performed such that the pitch of the ink droplet landing positions is larger in the Y direction than in the X direction, then ink coalescence occurs first between adjacent landing positions in the X direction, and then between adjacent landing positions in the Y direction. Immediately after ink coalescence occurs between adjacent landing positions in the Y direction, the ink layer is thicker at and near the landing position, and thinner at positions further away from the landing position. Therefore, by curing the ink layer in this state, a filling layer 36 having protrusions P on its surface can be obtained.

[0078] The inorganic barrier layer 37 covers the upper surfaces of the filler layers 36R, 36G, and 36B, the areas of the inorganic coating layer 35 that are exposed from the filler layers 36R, 36G, and 36B, and the areas of the upper surface of the resin layer 34 that are exposed at the openings of the inorganic coating layer 35. The inorganic barrier layer 37 is interposed between the filler layers 36R, 36G, and 36B and the adhesive layer 4, preventing the migration of moisture from the adhesive layer 4 to the filler layers 36R, 36G, and 36B.

[0079] The inorganic barrier layer 37 has light transmittance, allowing light emitted by the light-emitting diode 23 to pass through. The inorganic barrier layer 37 may have a single-layer structure or a multilayer structure. For example, the inorganic barrier layer 37 includes at least one of a layer made of silicon oxide and a layer made of silicon nitride. The layers included in the inorganic barrier layer 37 can be formed, for example, by vapor deposition methods such as chemical vapor deposition and sputtering.

[0080] Furthermore, the inorganic barrier layer 37 has water vapor barrier properties. The thickness of the inorganic barrier layer 37 is preferably within the range of 1 μm to 3 μm. For example, the inorganic barrier layer 37 has a water vapor transmission rate of 10 as defined in JIS K7129:2019. -2 g / m 2 It is less than or equal to / day.

[0081] The adhesive layer 4 is interposed between the dimming device 2 and the wavelength conversion substrate 3A, bonding them together. The adhesive layer 4 transmits the light emitted by the light-emitting diode 23. The adhesive layer 4 is, for example, a colorless and transparent layer. The adhesive layer 4 is made of an adhesive or tack.

[0082] The above-described display device 1A may have excellent display performance. This will be explained below.

[0083] The light-emitting portion of the light-emitting diode 23 is smaller than the opening on the dimming device 2 side of the through-hole provided in the partition wall. In the display device 1A, since the through-hole provided in the partition wall has a shape that extends in the Y direction, the light-emitting portion of the light-emitting diode 23 is particularly small in the Y direction compared to the opening on the dimming device 2 side of the through-hole provided in the partition wall.

[0084] The light emitted by the light-emitting diode 23 is diffuse light, not parallel light. Therefore, the light emitted by the light-emitting diode 23 is incident not only on the region of the packed layer directly in front of the light-emitting part of the light-emitting diode 23, but also on other regions.

[0085] However, as described above, the dimensions of the light-emitting portion are particularly small in the Y direction compared to the opening in the partition wall. Therefore, there is a large difference in the intensity of light reaching the surface between the region of the packing layer located approximately in front of the light-emitting portion (hereinafter referred to as the intermediate region) and the pair of regions of the packing layer adjacent to each other in the Y direction with the intermediate region in between (hereinafter referred to as the end regions).

[0086] Furthermore, if the surface of the wavelength conversion layer is flat, the angle of incidence of the light emitted by the light-emitting diode 23 onto the wavelength conversion layer is small in the intermediate region and large in the edge region. Therefore, much of the light that reaches the surface of the intermediate region is incident on the wavelength conversion layer, while much of the light that reaches the surface of the edge region is reflected by the wavelength conversion layer.

[0087] Therefore, in the intermediate region of a wavelength conversion layer with a flat surface, some of the incident light may pass through the intermediate region without being wavelength converted due to the high intensity of the incident light and the small angle of incidence. Also, in the edge region of a wavelength conversion layer with a flat surface, the quantum dots may not be effectively utilized for wavelength conversion due to the low intensity of the light reaching the surface and the reflection of much of the reaching light. For this reason, wavelength conversion layers with a flat surface have low wavelength conversion efficiency.

[0088] Furthermore, if the surface of the packed layer is flat, the reflection of ambient light from this surface can have a significant impact on the display. For example, when ambient light is incident on pixels containing the first colored layer 33R while they are not illuminated, some of the colored light that passes through the first colored layer 33R is reflected by the surface of the packed layer and emitted outside the display device. Although this reflected light is weak, it can degrade the display performance.

[0089] In the above-described display device 1A, the surface of the wavelength conversion layer has the aforementioned protrusions P. In the intermediate region, the sloped region created by the protrusions P can play a role in diffusing incident light over a wide angle. On the other hand, in the edge region, the sloped region created by the protrusions P can play a role in reducing reflection. Therefore, by adopting the above-described structure for the display device 1A, for example, it is possible to promote wavelength conversion in the edge region while preventing some of the incident light from passing through the intermediate region, and thus high wavelength conversion efficiency can be achieved. In addition, the sloped region created by the protrusions P scatters ambient light incident on unlit pixels, and therefore reduces its effect on the display. In other words, by adopting the above-described structure for the display device 1A, excellent display performance can be achieved.

[0090] Furthermore, even when the packed layer is a non-wavelength conversion layer, if its surface has the aforementioned protrusions P, reflection in the edge region can be reduced. Therefore, the light extraction efficiency can be improved.

[0091] <2> Second Embodiment Figure 5 is an enlarged top view showing a portion of the wavelength conversion substrate included in the display device according to the second embodiment of the present invention. Figure 6 is a cross-sectional view of the wavelength conversion substrate shown in Figure 5 along the line VI-VI. Note that in Figure 5, as in Figure 3, contour lines are superimposed on the packed layer 36.

[0092] The display device according to the second embodiment is the same as the display device 1A described above, except that it includes a wavelength conversion substrate 3B shown in Figures 5 and 6 instead of the wavelength conversion substrate 3A. Furthermore, the wavelength conversion substrate 3B is the same as the wavelength conversion substrate 3A described above, except that the protrusions P provided on the surface of the packed layer 36 have the structure described below.

[0093] Specifically, in the packed layer 36 of the wavelength conversion substrate 3B, similar to the packed layer 36 of the wavelength conversion substrate 3A, the protrusions P each extend in the second direction, the X direction, and are arranged in the first direction, the Y direction, creating a sloped region on the surface of the packed layer 36. In addition, in the packed layer 36 of the wavelength conversion substrate 3B, the height of each protrusion P at the center is higher than the height at both ends in the X direction.

[0094] Here, each of the convex portions P has an approximately elliptical shape when projected onto a plane perpendicular to the Z direction. Furthermore, each of the convex portions P has the greatest height at its center and decreases in height towards its periphery. For each of the convex portions P, the maximum curvature of the cross section passing through its apex and parallel to the Z and X directions is smaller than the maximum curvature of the cross section passing through its apex and parallel to the Z and Y directions.

[0095] The filling layer 36 can be formed, for example, by the following method. First, a first layer made of the above-mentioned ink is formed on the upper surface of the color filter 33 in the region corresponding to the convex portion P, in this case, in the region where each portion has a substantially elliptical shape. Next, the first layer is cured or partially cured. Then, a second layer made of the above-mentioned ink is formed in the through-hole of the partition wall. The second layer is formed thinly, for example, such that the height of the upper surface at the position of the gap in the pattern formed by the first layer is lower than the height of the upper surface of the first layer. After that, the second layer is cured. If the first layer is partially cured, the first layer is fully cured when the second layer is cured. In this way, the filling layer 36 shown in Figures 5 and 6 is obtained.

[0096] This filling layer 36 can also be formed by other methods. Specifically, an ink with sufficiently high viscosity is used, and inkjet printing is performed such that the pitch of the ink droplets' landing positions is larger in the Y direction compared to the X direction. Furthermore, the landing positions of the ink droplets are spaced sufficiently apart from the side walls of the through-holes in the partition wall that extend in the Y direction. In this way, ink unification occurs first between adjacent landing positions in the X direction, and then between adjacent landing positions in the Y direction. Immediately after ink unification occurs between adjacent landing positions in the Y direction, the ink layer is thicker at and near the landing positions, and thinner at positions further away from the landing positions. Also, since the landing positions of the ink droplets are spaced sufficiently apart from the side walls of the through-holes in the partition wall that extend in the Y direction, the thickness of the ink layer near these side walls is smaller than the thickness of the ink layer at or near the landing positions. Therefore, by curing the ink layer in this state, the filled layer 36 described with reference to Figures 5 and 6 can be obtained.

[0097] The protrusions P on the surface of the packed layer 36 of the wavelength conversion substrate 3B can perform a similar role to the protrusions P on the surface of the packed layer 36 of the wavelength conversion substrate 3A. In addition, the protrusions P on the surface of the packed layer 36 of the wavelength conversion substrate 3B can produce a light-focusing effect in the X direction. Therefore, the display device according to the second embodiment can achieve a higher light extraction efficiency compared to the display device 1A. In other words, the second embodiment can achieve even better display performance.

[0098] <3> Variation The display device and wavelength conversion substrate described above can be modified in various ways. For example, although a micro-LED display was used as an example of a display device here, the technology described above can also be applied to other displays such as organic electroluminescent displays and liquid crystal displays. [Explanation of symbols]

[0099] 1A...Display device, 3A...Wavelength conversion substrate, 3B...Wavelength conversion substrate, 4...Adhesive layer, 21...Substrate, 22...Multilayer wiring layer, 23...Light-emitting diode, 31...Transparent substrate, 32...Black matrix, 33...Color filter, 33B...Underlayer, 33G...Second coloring layer, 33R...First coloring layer, 34...Resin layer, 35...Inorganic coating layer, 36...Filling layer, 36B...Filling layer, 36G...Filling layer, 36R...Filling layer, 37...Inorganic barrier layer, P...Convex part, R...Concave part.

Claims

1. A transparent substrate having a first main surface and a second main surface, A resin layer provided on the first main surface, having a plurality of through holes, each of which has a shape extending in a first direction parallel to the first main surface, Each of the aforementioned multiple through holes is filled, and at least one of the multiple packed layers is a wavelength conversion layer containing quantum dots. Equipped with, The wavelength conversion substrate has a plurality of protrusions on its surface that are parallel to the first main surface and extend in a second direction intersecting the first direction, and are arranged in the first direction, with the plurality of protrusions creating a sloped region on the surface.

2. The wavelength conversion substrate according to claim 1, wherein each of the plurality of protrusions has a height at its central portion that is higher than the height at both ends in the second direction.

3. The wavelength conversion substrate according to claim 1, wherein the pitch T of the arrangement of the plurality of protrusions in the first direction is within the range of 10 μm to 50 μm.

4. The wavelength conversion substrate according to claim 1, wherein the ratio H / T of the height H of the plurality of protrusions to the pitch T of the arrangement of the plurality of protrusions in the first direction is within the range of 0.05 or more and 0.5 or less.

5. The wavelength conversion substrate according to claim 1, wherein each of the plurality of through holes has a ratio L / W of the aperture diameter L in the length direction to the aperture diameter W in the width direction, which is in the range of 1.1 to 5.

6. The wavelength conversion substrate according to claim 1, wherein the height H of the plurality of protrusions is within the range of 10% to 15% of the thickness of the resin layer.

7. The wavelength conversion substrate according to claim 1, wherein the volume of each of the plurality of packed layers is within the range of 1 to 1.3 times the volume of each of the plurality of through holes.

8. A wavelength conversion substrate according to any one of claims 1 to 7, A dimming device installed so as to face the first main surface and A display device equipped with the following features.

9. The display device according to claim 8, comprising a substrate and a plurality of light-emitting diodes arranged on the substrate corresponding to the plurality of through holes.

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