Display device

Abstract

The purpose of this invention is to provide a display device capable of suppressing damage to a color filter and a microlens. A display device according to the present invention is characterized in that a light-emitting element, a color filter and / or a microlens, a resin layer, and a cover layer are laminated in this order on a substrate, and the resin layer includes a hard coat layer having a pencil hardness of H or more. In the present invention, it is preferable that the resin layer includes the hard coat layer formed by curing a resin composition containing acrylic resin, an acrylic monomer, and an initiator, 31 mass% or more of the constitutional unit of the hard coat layer is derived from the acrylic monomer, and the mass ratio of the constitutional unit derived from the acrylic monomer to the acrylic resin is 1.2 or more.

Description

display device

[0001] The present invention relates to a display device equipped with a light-emitting element.

[0002] For example, display devices equipped with organic electroluminescence (EL) elements, which are self-emitting elements, are excellent in terms of thinness and lightness, and development is underway to improve their performance.

[0003] As shown in Patent Documents 1 and 2, for example, a display device has organic light-emitting elements and color filters laminated on a substrate, and further has a cover layer bonded to the surface of the color filter via an adhesive layer.

[0004] Patent No. 7010279 Patent No. 6605559

[0005] However, the color filter does not have sufficient hardness, and in the case of a configuration in which a microlens is superimposed on a color filter, the microlens does not have sufficient hardness, so there is a problem that the color filter and the microlens are easily scratched in the process of bonding the cover layer. Note that this problem is not limited to organic EL microdisplays, but also occurs in micro LED displays.

[0006] An object of the present invention is to provide a display device that can prevent color filters and microlenses from being scratched.

[0007] A display device according to one aspect of the present invention is characterized in that a light-emitting element, a color filter and / or a microlens, a resin layer, and a cover layer are stacked in this order on a substrate, and the resin layer includes a hard coat layer having a pencil hardness of H or higher.

[0008] Furthermore, a display device according to one aspect of the present invention includes a substrate on which a light-emitting element, a color filter and / or a microlens, a resin layer, and a cover layer are laminated in this order, the resin layer including a hard coat layer formed by curing a resin composition containing at least an acrylic resin, an acrylic monomer, and an initiator, the hard coat layer containing 31% by mass or more of structural units derived from the acrylic monomer, and the mass ratio of the structural units derived from the acrylic monomer to the structural units derived from the acrylic resin is 1.2 or more.

[0009] According to the present invention, it is possible to prevent the color filters and microlenses from being damaged, thereby improving the display quality.

[0010] 1 is a schematic cross-sectional view of a display device according to a first embodiment. 2 is a schematic cross-sectional view of a display device according to a second embodiment. 3 is a schematic cross-sectional view of a display device according to a third embodiment. 4 is a schematic cross-sectional view showing a manufacturing process of a display device according to the present embodiment. 5 is a schematic cross-sectional view showing a manufacturing process of a display device according to the present embodiment. 6 is a schematic cross-sectional view of a display device for explaining problems in a conventional example. 7 is a schematic cross-sectional view of a display device for explaining problems in a conventional example. 8 is a schematic cross-sectional view of a display device for explaining problems in a conventional example. 9 is a schematic cross-sectional view of a display device for explaining problems in a conventional example.

[0011] An embodiment of the present invention (hereinafter abbreviated as "embodiment") will be described in detail below. The present invention is not limited to the following embodiment, and can be practiced with various modifications within the scope of the gist. The notation "to" includes both the lower limit and upper limit (boundary value).

[0012] 1 is a schematic cross-sectional view of a display device according to a first embodiment. The display device 1 is an organic EL microdisplay. The display device 1 includes an organic light-emitting element (organic EL element) 3, a color filter 4, a microlens 5, a hard coat layer 6, and a cover glass 7 stacked in this order on a circuit board 2 from the bottom.

[0013] The circuit board 2 includes a silicon substrate and an array section located on the upper surface of the silicon substrate. The array section includes pixel circuits and wiring for supplying signals and power to the pixel circuits. The pixel circuits include transistors as drive elements and switches, capacitors, and wiring for connecting them to each other. The transistors are, for example, field-effect transistors that include part of the surface region of the silicon substrate as source regions, channel regions, and drain regions.

[0014] The organic light-emitting element 3 is configured to include a first electrode 8, an organic light-emitting layer (organic EL layer) 9, a partition layer 10 positioned around the organic light-emitting layer 9, and a second electrode 11. Note that an insulating layer and the like interposed between the circuit board 2 and the organic light-emitting element 3 are not shown.

[0015] The organic light-emitting layer 9 is configured to emit white light by injecting electric charges, for example, and existing organic materials can be used for the organic light-emitting layer 9 .

[0016] As shown in FIG. 1 , a color filter 4 is formed on the surface of the organic light-emitting element 3 via a base layer 12. The base layer 12 may be made of either an inorganic or organic material. For example, it may have a laminated structure of an inorganic layer / an organic layer. Examples of the inorganic layer include oxides and nitrides, and it serves as a sealing layer that covers the surface of the organic light-emitting element 3. The organic layer is made of an existing material such as acrylic resin, and serves to flatten the base of the color filter 4.

[0017] The color filter 4 is formed on the surface of the base layer 12 and has the function of transmitting light in any of the wavelength bands of red (R), green (G), and blue (B), which are the three primary colors of light.

[0018] A microlens 5 is provided on the surface of each color filter 4. The microlens 5 is a so-called plano-convex lens having a bottom surface and a lens surface. The curvature and shape of the lens surface are appropriately designed according to the refractive index at visible wavelengths of the material of the microlens 5. By providing the microlens 5, it is possible to suppress the spread of light emitted from the display emission surface 7a, which is the surface of the display device 1, and to achieve high contrast.

[0019] The hard coat layer 6 is a resin layer formed by curing a resin composition (photosensitive composition). As shown in Fig. 1, the hard coat layer 6 covers the irregularities on the surface of the microlens 5 and has a substantially flat surface 6a. The surface 6a of the hard coat layer 6 is flattened relative to the surface of the microlens 5. Here, "flattened" means absorbing the irregularities on the surface of the microlens 5 and making it flatter than the surface of the microlens 5, and is not limited to being completely flat.

[0020] As shown in FIG. 1, a cover glass 7 is adhered and fixed to a surface 6 a of the hard coat layer 6 via an adhesive layer 13 .

[0021] Although a transparent substrate resin or the like can be exemplified instead of the cover glass 7, it is preferable to use the cover glass 7 as the cover layer in consideration of durability, transmittance, refractive index, etc. As shown in Fig. 1 , the cover glass 7 is attached by applying an adhesive to the surface 6a of the hard coat layer 6. The cover glass 7 protects the organic light-emitting element 3, the color filter 4, and the microlens 5 from external impact, damage, etc.

[0022] <Regarding Other Embodiments> Fig. 2 is a schematic cross-sectional view of a display device according to a second embodiment. Fig. 3 is a schematic cross-sectional view of a display device according to a third embodiment. Note that the same reference numerals as in Fig. 1 indicate the same layers as in Fig. 1, so please refer to Fig. 1 for a detailed explanation. Here, the differences from Fig. 1 will be mainly explained.

[0023] 2, unlike in Fig. 1, the microlens 5 is not provided, and therefore the hard coat layer 6 is formed on the color filter 4 in Fig. 2.

[0024] In FIG. 3 , an overcoat layer 14 is formed to cover the surface of the microlenses 5, and a hard coat layer 6, an adhesive layer 13, and a cover glass 7 are laminated on the overcoat layer 14 in this order. In this embodiment, the overcoat layer 14 and the hard coat layer 6 together constitute a resin layer 20. The overcoat layer 14 may have a lower pencil hardness than the hard coat layer 6. That is, the pencil hardness of the overcoat layer 14 may be H or less. On the other hand, the overcoat layer 14 has a lower thermal expansion coefficient than the hard coat layer 6, for example. By selecting a material with a low thermal expansion coefficient, the uneven surface of the microlenses 5 can be appropriately filled and a flat surface 14a can be easily obtained. Furthermore, by using a material with a lower refractive index than the microlenses 5, for example, the light-collecting effect of the microlenses 5 can be enhanced, thereby improving the front brightness of the display device 1. In this way, using a material with a low refractive index for the overcoat layer 14 widens the range of materials available for the hard coat layer 6. Existing materials such as acrylic resin and epoxy resin can be used for the overcoat layer 14.

[0025] 3, the hard coat layer 6 can be formed with a constant thickness on the surface 14a of the overcoat layer 14, and the surface 6a of the hard coat layer 6 can also be formed as a flat surface. By forming the resin layer 20 with a laminated structure of the overcoat layer 14 / hard coat layer 6, even if the hard coat layer 6 is formed thin enough to obtain a predetermined pencil hardness, the optical path length from the organic light-emitting layer 9 to the display output surface 7a can be appropriately adjusted to be within a predetermined range.

[0026] Furthermore, rather than forming the hard coat layer 6 and the overcoat layer 14 in this order on the microlenses 5, it is preferable to laminate the overcoat layer 14 and the hard coat layer 6 in this order, as in the present embodiment. In particular, in a configuration having the microlenses 5, it is necessary to fill the uneven surfaces of the microlenses 5 with precision, and therefore, it is preferable to first form the overcoat layer 14 and then form the hard coat layer 6, which has a high pencil hardness, in order to properly fill the uneven surfaces of the microlenses 5. Alternatively, the resin layer 20 can also be formed, for example, in a laminated structure of overcoat layer / hard coat layer / overcoat layer.

[0027] In this embodiment, the structure of the resin layer 20 is not limited as long as the resin layer 20 includes the hard coat layer 6 having a pencil hardness of H or more.

[0028] <Technical Background and How the Display Device 1 of the Present Embodiment Was Produced> For example, in the process of manufacturing an organic EL display device, there is a process of bonding a cover glass 7 after forming a microlens 5 on a color filter 4 as shown in FIGS. 1 and 3, or after forming the color filter 4 as shown in FIG. 2.

[0029] Here, the conventional process of bonding the cover glass 7 will be described. As shown in Fig. 5A, adhesive 15 is applied to the surface of the microlens 5, and then the cover glass 7 is bonded to the microlens 5 as shown in Fig. 5B. Reference numeral 16 in Fig. 5B denotes an adhesive layer formed by hardening the adhesive 15.

[0030] However, because the microlenses 5 did not have sufficient hardness, the microlenses 5 were damaged during the process of bonding the cover glass 7, resulting in scratches on the surface of the microlenses 5. This reduced the lens function of the microlenses 5, leading to a decrease in display quality. Figure 5B schematically shows a state in which a scratch A has appeared on the surface of the microlenses 5. Note that the color filter 4 also did not have sufficient hardness, and scratches were still formed on the surface of the color filter 4 even in a configuration in which the cover glass 7 was bonded onto the color filter 4 via adhesive 15 without forming the microlenses 5.

[0031] On the other hand, it is difficult to increase the hardness of the color filters 4 and the microlenses 5. That is, in organic EL display devices for microdisplays, the color filters 4 and the microlenses 5 are mainly processed by an on-chip method to realize fine pixel formation. In the on-chip method, the color filters 4 and the microlenses 5 are processed directly on the organic light-emitting layer 9. However, the organic light-emitting layer 9 has a problem with heat resistance, so low-temperature processing is required. Specifically, each component needs to be processed at 100°C or below. However, such low-temperature processing makes it difficult to fully develop the hardness of each component. For this reason, as described above, it is not possible to sufficiently increase the hardness of the color filters 4 and the microlenses 5. As a result, a problem of scratches on the color filters 4 and the microlenses 5 occurs during the process of bonding the cover glass 7.

[0032] Furthermore, as shown in FIG. 6A, by applying a thick layer of adhesive 15 and then bonding the cover glass 7, a thick adhesive layer 16 can be formed between the cover glass 7 and the microlens 5 as shown in FIG. 6B, which makes the color filter 4 and the microlens 5 less susceptible to scratches.

[0033] However, the amount of adhesive 15 used increases, resulting in higher costs, and the length of the optical path from the organic light-emitting layer 9 to the display light output surface increases, making it more likely that light from adjacent pixels will mix colors.

[0034] Patent Documents 1 and 2 do not address the problem of scratches on the color filter 4 or microlens 5 during the process of bonding the cover glass 7, and do not provide a detailed explanation of the hardness of the resin curing layer (referred to as an adhesive or overcoat layer) used between the cover glass 7 and the color filter 4. Moreover, the curing temperature of the resin composition used in the resin layer typically exceeds 100°C, and the resin cannot be sufficiently cured at temperatures below 100°C. The above-mentioned problems arise not only in organic EL display devices but also in micro LED display devices.

[0035] Therefore, as a result of extensive research, the inventors focused on the pencil hardness of the resin layer located between the color filter 4 and / or microlens 5 and the cover glass 7, and were able to improve the prevention of scratches on the color filter 4 and microlens 5 during the process of bonding the cover glass 7.

[0036] <Detailed Description of Hard Coat Layer 6 According to the Present Embodiment> (1. Pencil Hardness) In the display device 1 according to the present embodiment, a hard coat layer 6 having a pencil hardness of H or more is provided on a resin layer located between the color filter 4 and / or the microlens 5 and the cover glass 7. Here, the "pencil hardness" is measured by the method specified in JIS K 5600-5-4.

[0037] The pencil hardness is preferably 2H or more, more preferably 3H or more, even more preferably 4H or more, and most preferably 5H or more.

[0038] By adjusting the pencil hardness to H or higher, scratches on the microlenses 5 and color filters 4 can be suppressed during the process of bonding the cover glass 7. Although the reason for this is unclear, it is presumed that a pencil hardness of H or higher can provide a hardness that is less susceptible to plastic deformation and cohesive failure, effectively reducing the pressure applied to the color filters and microlenses when the cover glass 7 is bonded. Note that "scratches" refer to marks such as scratches, dents, or lines. As described above, the pencil hardness is preferably 2H or higher, and according to the experiments described below, the pencil hardness can be increased to 4H or higher, or even 5H or higher. In this way, in this embodiment, the pencil hardness of the hard coat layer 6 can be adjusted to a gradually higher value. The upper limit of the pencil hardness is not limited, and the hardest value of 9H can be set as the upper limit.

[0039] (2. Resin Material Used in Hard Coat Layer 6) The hard coat layer 6 of the present embodiment is a cured film obtained by curing a resin composition (photosensitive composition) containing at least an acrylic resin, an acrylic monomer, and an initiator in a solvent, and the cured film contains at least, as solid components, a structural unit derived from the acrylic resin, a structural unit derived from the acrylic monomer, and the initiator.

[0040] In this embodiment, the hard coat layer 6 contains 31% by mass or more of structural units derived from acrylic monomers.

[0041] Additionally, in this embodiment, the weight ratio of the structural units derived from the acrylic monomer / the structural units derived from the acrylic resin is 1.2 or more.

[0042] Here, "structural unit derived from" refers to the structural unit derived from, and refers to the chemical structure remaining in the polymer after the corresponding component has been polymerized, or, if the original state (state in the resin composition) can be inferred from that chemical structure, the chemical structure in the state before polymerization. Monomer-derived and resin (polymer)-derived components can be observed by NMR spectroscopy or IR spectroscopy, and the mass can be calculated based on the spectrum. Alternatively, if the amounts of the components in the resin composition (photosensitive composition) are known, these values ​​can be used to substitute the mass percentage of acrylic monomer in the solid component and the mass ratio of acrylic monomer / acrylic resin.

[0043] The acrylic resin is a polymer of an acrylic acid ester or a methacrylic acid ester. The acrylic monomer can be one or more selected from methyl acrylate, ethyl acrylate, butyl acrylate, propyl acrylate, pentyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, lauryl acrylate, acrylamide, vinyl acetate, acrylonitrile, methyl methacrylate, ethyl methacrylate, butyl methacrylate, propyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, dodecyl methacrylate, lauryl methacrylate, etc.

[0044] The initiator may be contained in an amount sufficient to promote polymerization of the monomers, and the effects of the present embodiment can be obtained regardless of the type of initiator. The initiator may be selected from, but is not limited to, an oxime ester initiator, an acetophenone compound, a benzoin compound, a benzophenone compound, a thioxanthone compound, a triazine compound, a phosphine compound, a quinone compound, a borate compound, a carbazole compound, an imidazole compound, or a titanocene compound.

[0045] The content of structural units derived from acrylic monomers is preferably 35% by mass or more, and more preferably 38% by mass or more.

[0046] Furthermore, the weight ratio of the structural units derived from the acrylic monomer to the structural units derived from the acrylic resin is preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 2.5 or more.

[0047] In this way, by adjusting the composition ratio and mass ratio of the acrylic monomers, the degree of polymerization in the cured film is increased, and the pencil hardness can be adjusted to H or higher, preferably 2H or higher, and more preferably 5H or higher, which effectively prevents the microlens 5 and color filter 4 from being scratched during the process of bonding the cover glass 7.

[0048] In this embodiment, the hard coat layer 6 may contain components other than the acrylic resin, acrylic monomer, and initiator as solid components. For example, a pigment may be contained. In this embodiment, the pigment may be selected from known pigments and dyes depending on the color of a desired pixel. The content of the pigment is not limited, but may be equal to or greater than the content of the structural unit derived from the acrylic monomer.

[0049] Here, the content of the structural units derived from the acrylic monomers listed above (31% by mass or more, preferably 35% by mass or more, and more preferably 38% by mass or more) is within a range regardless of whether or not a pigment is present. However, when no pigment is present, the content of the structural units derived from the acrylic monomers can be 70% by mass or more.

[0050] Furthermore, in a configuration in which the hard coat layer 6 does not contain a pigment, the mass ratio of the structural units derived from the acrylic monomer / the structural units derived from the acrylic resin can be 4.0 or more, and further 4.5 or more.

[0051] The above-mentioned numerical ranges include measurement errors. Also, deviations from the numerical ranges occur depending on how the values ​​are rounded. Therefore, in this embodiment, the analytical values ​​are assumed to include a tolerance of approximately ±10%, preferably ±5%.

[0052] (3. Film Thickness of Hard Coat Layer 6) The film thickness of the hard coat layer 6 is preferably 0.5 μm or more and 10.0 μm or less. The film thickness is more preferably 0.8 μm or more, and even more preferably 1.0 μm or more. The film thickness is more preferably 7.0 μm or less, and even more preferably 5.0 μm or less. This allows for accurate pencil hardness of H or more, preferably 2H or more, and more preferably 5H or more. Furthermore, the optical path length from the organic light-emitting layer 9 to the display light-emitting surface 7a can be adjusted to an appropriate length, effectively suppressing the occurrence of color mixing of light between adjacent pixels. Note that the "film thickness of the hard coat layer 6" in this embodiment refers to the minimum value. For example, if it is on a microlens 5, it refers to the thickness in the vertical direction from the top of the microlens 5 to the top surface of the hard coat 6 layer.

[0053] (4. Other Points) The hard coat layer 6 preferably has an average transmittance of 95% or more for wavelengths of 400 nm to 800 nm, which can increase the light extraction efficiency of the hard coat layer 6 and improve the brightness of the display.

[0054] The refractive index of the hard coat layer 6 is preferably lower than that of the microlenses 5 and color filters 4 that are in contact with the lower layer side (organic light-emitting element 3 side) of the hard coat layer 6, and higher than that of the adhesive layer 13 that is in contact with the upper layer side (cover glass 7 side) of the hard coat layer 6. In the embodiment shown in Fig. 1, the refractive index of the hard coat layer 6 is preferably lower than that of the microlenses 5 and higher than that of the adhesive layer 13. In the embodiment shown in Fig. 2, the refractive index of the hard coat layer 6 is preferably lower than that of the color filters 4 and higher than that of the adhesive layer 13.

[0055] The refractive index decreases in the order of organic light-emitting layer 9, color filter 4, microlens 5, hard coat layer 6, adhesive layer 13, and cover glass 7, thereby achieving excellent light-collecting properties and increasing brightness.

[0056] <Regarding the Manufacturing Method of the Display Device According to the Present Embodiment> The lamination from the hard coat layer 6 to the cover glass 7 will be mainly described.

[0057] As shown in FIG. 4B , after the microlenses 5 are formed on-chip, a photosensitive composition is applied to the surface of the microlenses 5. The photosensitive composition contains an acrylic monomer, an acrylic resin, and an initiator in a solvent. A pigment may also be added. At this time, the content of the acrylic monomer in the solid components is adjusted to 31% by mass or more, and the weight ratio of the acrylic monomer to the acrylic resin is adjusted to 1.2 or more.

[0058] In the case of the display device of FIG. 2, the photosensitive composition is applied to the surface of the color filter 4, and in the case of the display device of FIG. 3, the photosensitive composition is applied to the surface of the overcoat layer 14. Any existing method can be used for the application method. The photosensitive resin is then dried on a hot plate. Although not limited, the drying temperature is about 50° C. or higher and 70° C. The drying time is about several tens of seconds to several minutes. This evaporates the solvent contained in the photosensitive resin.

[0059] Next, an exposure process is performed. Although not limited to this, the exposure process may be performed at an illuminance of several tens of thousands of W / m ２ Using i-rays of about several thousand J / m ２ The composition is then further cured by heating on a hot plate at a temperature of 80° C. to 100° C. for several tens of minutes. ２ ~5000 J / m ２ Generally, if the temperature is within this range, the initiator will react sufficiently, and a pencil hardness of H or more, preferably 2H or more, and more preferably 5H or more can be appropriately and reliably obtained.

[0060] As a result, a hard coat layer 6 having a pencil hardness of H or higher can be formed at a temperature of 100° C. or lower. As shown in FIG. 4A , the hard coat layer 6 fills in the irregularities on the surface of the microlens 5. Furthermore, the surface 6 a of the hard coat layer 6 becomes a flat surface.

[0061] Next, as shown in Fig. 4A, an adhesive 15 is applied to the surface 6a of the hard coat layer 6, and as shown in Fig. 4B, a cover glass 7 is attached. An existing adhesive can be used as the adhesive 15. For example, a photocurable adhesive, a UV curable adhesive, a thermosetting adhesive, or the like can be used as the adhesive 15. This allows the cover glass to be adhered and fixed to the surface 6a of the hard coat layer 6 via the adhesive layer 13.

[0062] 3, when the resin layer 20 is not a single layer of the hard coat layer 6 but also includes other resin layers such as an overcoat layer 14, the other resin layers are also formed at a temperature of 100° C. or less. In this case, the pencil hardness of the other resin layers may be H or less.

[0063] <Effects of the Display Device According to the Present Embodiment> In the present embodiment, as shown in Fig. 4A, a hard coat layer 6 having a pencil hardness of H or more is formed on the surface of the microlens 5, an adhesive 15 is applied to the surface 6a of the hard coat layer 6, and a cover glass 7 is attached thereto as shown in Fig. 4B. Therefore, compared to the conventional example shown in Figs. 5A and 5B in which the hard coat layer 6 is not formed and adhesive 15 is applied directly to the surface of the microlens 5, and the cover glass 7 is attached thereto, in the present embodiment, the surface of the microlens 5 is protected by the hard hard coat layer 6, so that it is possible to prevent scratches A from being caused on the microlens 5 in the process of attaching the cover glass 7, as in the conventional example.

[0064] In addition, in order to prevent scratches on the microlenses 5, the amount of adhesive 15 applied is increased in FIG. 6A, resulting in a significantly thicker adhesive layer 16 as shown in FIG. 6B. However, the increased amount of adhesive 15 used increases costs and prevents the display device from being made thinner. In contrast, in this embodiment, the amount of adhesive 15 used can be reduced by providing a hard coat layer 6 having a pencil hardness of H or higher that covers the front side of the microlenses 5 and the color filter 4. Furthermore, in this embodiment, the film thickness of the hard coat layer 6 can be reduced to approximately 0.5 μm to 10.0 μm, thereby facilitating the thinning of the display device 1. By reducing the thickness of the hard coat layer 6 in this way, the optical path length from the organic light-emitting layer 9 to the display light-emitting surface 7a can be made appropriate, effectively suppressing color mixing between adjacent pixels.

[0065] Furthermore, in this embodiment, the amount of adhesive 15 used can be reduced, which makes it easier to adhere the cover glass 7 parallel to the substrate 2, and reduces unevenness in quality due to misalignment of the angle of the cover glass 7.

[0066] In the present embodiment, the hard coat layer 6 is formed by curing a resin composition containing at least an acrylic resin, an acrylic monomer, and an initiator, and the content of structural units derived from the acrylic monomer in the hard coat layer 6 is 31% by mass or more, and the mass ratio of structural units derived from the acrylic monomer / structural units derived from the acrylic resin is 1.2 or more. By forming the hard coat layer 6 with such a composition, the pencil hardness of the hard coat layer 6 can be adjusted to H or more even when the curing temperature is set to 100° C. or less, and the thermal effect on the organic light-emitting layer 9 can be reduced.

[0067] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to a specific embodiment and includes configuration changes and combinations within the scope of the present invention. For example, while the above description uses an organic EL microdisplay as an example, the organic light-emitting element 3 may be an LED (light-emitting diode), and therefore the display device may be a microLED display. For example, the LED may be a combination of a blue light-emitting element and quantum dots to convert blue to red or green. The microLED display can also achieve the effects of the display device described above by having a resin layer including a hard coat layer with a pencil hardness of H or higher.

[0068] The present invention will be described in detail below with reference to examples carried out to clarify the effects of the present invention, but the present invention is not limited to the following examples.

[0069] <Composition of Photosensitive Composition> A photosensitive composition was obtained by mixing and stirring a pigment, an acrylic monomer (M), an acrylic resin (P), and an oxytacene initiator (I) in a PGMEA solvent.

[0070] Photosensitive compositions were prepared for Experimental Examples 1 to 6. The composition ratios in each experiment are shown in Table 1.

[0071] <Regarding Formation of Hard Coat Layer> Each of the photosensitive compositions of Experimental Examples 1 to 6 was applied onto a color filter by spin coating, and then dried by heating on a hot plate at 70° C. for 1 minute.

[0072] Next, illuminance: 20,000 W / m ２ Exposure amount: 1000 J / m ２ , 3000 J / m ２ , or 5000 J / m ２ The coating was then exposed to light at 100° C. for 15 minutes on a hot plate to accelerate the curing.

[0073] In each experimental example, hard coat layers having thicknesses of 0.6 μm, 1.0 μm, and 2.0 μm were prepared.

[0074] <Pencil Hardness Test> The pencil hardness of the hard coat layer was measured under the following conditions in accordance with JIS K5600-5-4. Test method: An ISO pencil scratch hardness tester was used. Load on the pencil tip: 750 g. Pencil used: Mitsubishi Uni (6B-9H). Pencil lead adjustment: Only the wood was shaved, leaving the lead cylindrical. The tip had a smooth, circular cross section at 90 degrees. Pencil hardness definition: The hardest pencil that leaves no marks was used, and measurements were continued until the same result was obtained twice. Scratches on the hard coat layer were confirmed using a microscope (reflection magnification: 50x). The experimental results are shown below.

[0075]

[0076] As shown in Table 1, it was found that in Experimental Examples 1 and 2, the pencil hardness could be made H or higher regardless of the film thickness of the hard coat layer. On the other hand, in Experimental Examples 3 to 6, the pencil hardness was below H and was B or lower.

[0077] By having a pencil hardness of H or more as in Experimental Examples 1 and 2, cohesive failure does not occur in the process of bonding a cover glass onto the hard coat layer via an adhesive layer, and scratches on the color filter and microlenses can be effectively suppressed.

[0078] Comparing Experimental Examples 1 and 2 with Experimental Examples 3 to 6, differences were observed in the content of the acrylic monomer in the hard coat layer. That is, in Experimental Examples 1 and 2, the content of the acrylic monomer in the solid components was 31 mass% or more. Furthermore, in Experimental Examples 1 and 2, the mass ratio of acrylic monomer to acrylic resin (M / P) was 1.2 or more. Note that these values ​​were all calculated from the constituent components contained in the resin composition.

[0079] Experimental Example 1 contains a pigment, but Experimental Example 2 does not contain a pigment. It was found that when no pigment is contained, the content of the acrylic monomer in the solid component can be made 70 mass % or more.

[0080] Furthermore, with respect to pencil hardness, when the hard coat layer has a thickness of 1.0 μm as the standard, a pencil hardness of H or higher can be distinguished as an Example, and a pencil hardness below H can be distinguished as a Comparative Example. However, the pencil hardness tends to decrease as the thickness of the hard coat layer decreases, and it is preferable that the pencil hardness be H or higher even when the thickness is about 0.5 μm.

[0081] The upper limit of the thickness of the hard coat layer was set to 10 μm. Although the pencil hardness of the hard coat layer in Experimental Examples 1 and 2 could be ensured to be H or higher, if the thickness was too thick, the optical path length from the organic light-emitting layer to the display output surface would be longer, which could result in a deterioration in display quality. Therefore, the thickness was set to be more preferably 7 μm or less, and even more preferably 5 μm or less.

[0082] The exposure dose when forming the hard coat layer was 1000 J / m ２ ~5000 J / m ２ It was found that a hardness of about 100% was sufficient to obtain a pencil hardness of H or higher. It was also confirmed that the hard coat layers in Experimental Examples 1 and 2 had an average transmittance of 95% or higher in wavelengths of 400 nm to 800 nm. For the above reasons, Experimental Examples 1 and 2 were designated as Examples, and Experimental Examples 3 to 6 were designated as Comparative Examples.

[0083] According to the present invention, the cover glass can be attached without damaging the color filter or microlens, and the present invention can be used for organic EL type microdisplays and micro LED displays with excellent display quality.

[0084] This application is based on Japanese Patent Application No. 2024-021592, filed February 16, 2024, the contents of which are incorporated herein in their entirety.

Claims

1. A display device comprising a substrate on which a light-emitting element, a color filter and / or a microlens, a resin layer, and a cover layer are laminated in this order, and the resin layer includes a hard coat layer having a pencil hardness of H or higher.

2. A display device comprising: a light-emitting element, a color filter and / or microlens, a resin layer, and a cover layer laminated in this order on a substrate; the resin layer includes a hard coat layer formed by curing a resin composition containing at least an acrylic resin, an acrylic monomer, and an initiator; the hard coat layer contains 31% by mass or more of structural units derived from the acrylic monomer; and the mass ratio of the structural units derived from the acrylic monomer to the structural units derived from the acrylic resin is 1.2 or more.

3. The display device according to claim 2, wherein the hard coat layer has a pencil hardness of H or higher.

4. The display device according to claim 1 or 2, wherein the film thickness of the hard coat layer is 0.5 μm or more and 10.0 μm or less.

5. The display device according to claim 1 or 2, wherein the hard coat layer has an average transmittance of 95% or more for wavelengths of 400 nm to 800 nm.

6. A display device according to claim 1 or claim 2, characterized in that the refractive index of the hard coat layer is lower than that of the layer on the color filter side in contact with the hard coat layer, and higher than that of the layer on the cover layer side in contact with the hard coat layer.

7. The display device according to claim 1 or 2, characterized in that the cover layer is bonded to the surface of the resin layer via an adhesive layer.

8. The display device according to claim 1 or 2, wherein the light-emitting element is an organic light-emitting element.

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