LED display module and display screen

Abstract

The invention belongs to the technical field of LED display screens, and particularly relates to an LED display module and a display screen. The LED display module comprises a substrate, a plurality of LED light-emitting chips arranged on the substrate, transparent packaging layers arranged among the LED light-emitting chips and on the upper surfaces of the LED light-emitting chips, a black light-transmitting adhesive film layer arranged on the transparent packaging layers, and a micro-lens array layer arranged on the black light-transmitting adhesive film layer. The micro lens array layer comprises a micro lens array base layer and a micro lens array arranged on the micro lens array base layer. Compared with the prior art, the surface of the LED display module provided by the invention is the micro-lens array layer which is of the curved surface structure, so that the internal total reflection phenomenon when light is emitted into air from the module packaging structure can be effectively reduced, and the light emitting efficiency is improved, so that the ink color consistency can be effectively improved through the black light-transmitting adhesive film layer; and the light emitting efficiency can be improved through the compound eye micro lens array, and the brightness is improved under the condition that the power of the module is not increased.

Description

Technical Field

[0001] The invention belongs to the technical field of LED display screens, and in particular relates to an LED display module and a display screen. Background Art

[0002] COB (Chips on Board) packaging, or chip-on-board packaging technology, refers to fixing multiple LED light-emitting chips directly on a PCB substrate and then using resin materials for overall packaging. It has many advantages, including simple production process, high heat dissipation efficiency, and fine image quality. With the continuous iteration and maturity of COB packaging technology, its production cost is decreasing day by day, and it is gradually replacing the traditional SMT (Surface Mount Device) surface mounting technology and becoming a new development trend.

[0003] Due to the color differences between PCB substrates from different manufacturers or batches, the packaged modules often have inconsistent ink colors. After being spliced ​​into a large screen, the ink color differences between the modules in the off state greatly affect the visual effect and viewing experience, becoming one of the core issues that determine product competitiveness.

[0004] To solve this problem, researchers and related technicians have tried various methods, which are mainly divided into the following two technical routes. The first is to add melanin to the encapsulation glue to improve the ink color consistency of the module, but too much melanin will cause the overall brightness of the module to decrease. Another technical route is to stick a layer of black semi-transparent optical film on the surface of the encapsulation layer after it is cured, which will also greatly reduce the overall brightness of the display and cannot completely cover the differences in the base color of the PCB substrate. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide an LED display module and display screen with high ink color consistency and high light output efficiency.

[0006] The present invention provides an LED display module, comprising a substrate, a plurality of LED light-emitting chips arranged on the substrate, a transparent encapsulation layer arranged between the plurality of LED light-emitting chips and on the upper surface thereof, a black light-transmitting adhesive film layer arranged on the transparent encapsulation layer, and a microlens array layer arranged on the black light-transmitting adhesive film layer;

[0007] The microlens array layer comprises a microlens array base layer and a microlens array arranged on the microlens array base layer;

[0008] The microlens array layer includes resin and light diffusion particles dispersed in the resin.

[0009] Preferably, the thickness of the microlens array base layer is 5 to 500 microns;

[0010] The height of the microlens array is 3 to 100 micrometers.

[0011] Preferably, the microlens array comprises a plurality of microlenses; the diameter of the microlenses is 3 to 100 microns; the distance between adjacent microlenses is 1 to 100 microns; and / or the microlenses are compound eye lens structures.

[0012] Preferably, the mass of the light diffusion particles is 5% to 60% of the mass of the microlens array layer.

[0013] Preferably, the resin in the microlens array layer is selected from polydimethylsiloxane;

[0014] and / or, the light diffusion particles include one or more of silicon dioxide, silicone, titanium dioxide, polymethyl methacrylate, aluminum oxide and polystyrene;

[0015] And / or, the microlens array layer further includes one or more of a silane coupling agent, a hyperdispersant, a defoaming agent and a diluting solvent.

[0016] Preferably, the black light-transmitting adhesive film layer comprises modified resin, solid epoxy resin, curing agent, black particles and light-diffusing particles;

[0017] The modified resin includes silicone-modified epoxy resin and / or epoxy-modified silicone resin;

[0018] The mass ratio of the modified resin to the solid epoxy resin is 1:1 to 5:1.

[0019] Preferably, the epoxy equivalent of the solid epoxy resin is 1300 to 1950 g / eq;

[0020] And / or, the mass of the black particles in the black light-transmitting adhesive film layer is 0.1% to 6% of the mass of the black light-transmitting adhesive film layer;

[0021] And / or, the mass of the light diffusion particles in the black light-transmitting adhesive film layer is 0.1% to 6% of the mass of the black light-transmitting adhesive film layer.

[0022] Preferably, the overall visible light transmittance of the LED display module is greater than 40%;

[0023] And / or, the thickness of the black light-transmitting adhesive film layer is 5 to 300 microns;

[0024] And / or, the visible light transmittance of the black light-transmitting adhesive film layer is greater than 35%;

[0025] And / or, a silane coupling agent layer is provided between the transparent encapsulation layer and the black light-transmitting adhesive film layer and / or between the black light-transmitting adhesive film layer and the microlens array layer.

[0026] Preferably, the refractive index of the transparent encapsulation layer is 1.5 to 1.7;

[0027] And / or, the refractive index of the black light-transmitting adhesive film layer is 1.45 to 1.6;

[0028] And / or, the refractive index of the microlens array layer is 1.38-1.55.

[0029] The present invention also provides a display screen, comprising the above-mentioned LED display module.

[0030] The present invention provides an LED display module, including a substrate, a plurality of LED light-emitting chips arranged on the substrate, a transparent encapsulation layer arranged between the plurality of LED light-emitting chips and on their upper surfaces, a black light-transmitting adhesive film layer arranged on the transparent encapsulation layer, and a microlens array layer arranged on the black light-transmitting adhesive film layer; the microlens array layer includes a microlens array base layer and a microlens array arranged on the microlens array base layer; the microlens array layer includes a resin and light diffusion particles dispersed in the resin. Compared with the prior art, the surface of the LED display module provided by the present invention is a microlens array layer, which is a curved surface structure, which can effectively reduce the total internal reflection phenomenon when light is emitted from the module encapsulation structure into the air, and increase the light extraction efficiency, so that the ink color consistency can be effectively improved through the black light-transmitting adhesive film layer, and the light extraction efficiency can be improved through the compound eye microlens array, and the brightness can be improved without increasing the module power. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the structure of the LED display module provided by the present invention;

[0032] Figure 2 A schematic diagram of the structure of a microlens array layer provided by the present invention;

[0033] Figure 3 A schematic diagram of the preparation process of the LED display module provided by the present invention;

[0034] Figure 4 A schematic diagram of the preparation process of the black light-transmitting adhesive film layer provided by the present invention;

[0035] Figure 5 It is a cross-sectional view of the morphology of a single microlens in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The present invention provides an LED display module, comprising a substrate, a plurality of LED light-emitting chips arranged on the substrate, a transparent packaging layer arranged between the plurality of LED light-emitting chips and on the upper surface thereof, a black light-transmitting adhesive film layer arranged on the transparent packaging layer, and a microlens array layer arranged on the black light-transmitting adhesive film layer; the microlens array layer comprises a microlens array base layer and a microlens array arranged on the microlens array base layer; the microlens array layer comprises a resin and light diffusion particles dispersed in the resin.

[0038] See also Figure 1 , Figure 1 This is a schematic structural diagram of the LED display module provided by the present invention, wherein 100 is a substrate, 200 is an LED light-emitting chip, 300 is a transparent encapsulation layer, 400 is a black light-transmitting film layer, and 500 is a microlens array layer.

[0039] According to the present invention, the substrate can be any substrate well known to those skilled in the art without any special limitation. In the present invention, a PCB substrate is preferred.

[0040] According to the present invention, a plurality of LED light-emitting chips are arranged on the substrate; the distance between the plurality of LED light-emitting chips is preferably 0.2 to 2 mm, more preferably 0.5 to 1.5 mm, and even more preferably 0.9 to 1 mm.

[0041] According to the present invention, a transparent encapsulation layer is provided between the plurality of LED light-emitting chips and on their upper surfaces; the transparent encapsulation layer can be a transparent encapsulation layer well known to those skilled in the art, and is not particularly limited. In the present invention, it preferably includes one or more of epoxy resin, acrylic resin, silicone and polyurethane; in the embodiments provided by the present invention, a transparent modified epoxy resin ( 9311) is used as an example for explanation; the thickness of the transparent packaging layer on the upper surface of the LED light-emitting chip is preferably 0.1-1 mm, more preferably 0.3-0.8 mm, further preferably 0.4-0.6 mm, and most preferably 0.5 mm; the refractive index of the transparent packaging layer is preferably 1.5-1.7.

[0042] According to the present invention, a black light-transmitting adhesive film layer is arranged on the surface of the transparent encapsulation layer away from the substrate; the thickness of the black light-transmitting adhesive film layer is preferably 5 to 300 μm, more preferably 10 to 250 μm, more preferably 50 to 250 μm, more preferably 100 to 250 μm, more preferably 150 to 250 μm, most preferably 200 μm; the visible light transmittance of the black light-transmitting adhesive film layer is preferably greater than 35%; the refractive index of the black light-transmitting adhesive film layer is preferably 1.45 to 1.6.

[0043] In a specific embodiment provided by the present invention, the black light-transmitting adhesive film layer comprises a modified resin, a solid epoxy resin, a curing agent, black particles and light-diffusing particles; the mass ratio of the modified resin to the solid epoxy resin is preferably 1:1 to 5:1, more preferably 2:1 to 5:1, more preferably 3:1 to 5:1, and most preferably 4:1; the modified resin preferably comprises silicone-modified epoxy resin and / or epoxy-modified silicone resin; the resin material of the black light-transmitting adhesive film layer comprises silicone-modified epoxy resin and / or epoxy-modified silicone resin, which plays a good role between the microlens array (resin material is PDMS) and the transparent encapsulation layer (epoxy resin). The bridging and transition effects of the three can be formed by chemical cross-linking to form a stable combination, avoiding the occurrence of warping or falling off; the epoxy equivalent of the modified resin is preferably 150-250g / eq, more preferably 160-240g / eq, more preferably 170-220g / eq, more preferably 180-210g / eq, and most preferably 185-205g / eq; in some embodiments provided by the present invention, the modified resin is specifically one or more of liquid organosilicon-modified epoxy resin complex high-tech EPSI-3201, solid organosilicon-modified epoxy resin Dow Corning EP-2601 and Selvi SEI-7030; The epoxy equivalent of the solid epoxy resin is preferably 1300-1950 g / eq, more preferably 1400-1950 g / eq, more preferably 1400-1900 g / eq, and most preferably 1500-1800 g / eq; the mass of the curing agent is preferably 30%-70% of the total mass of the modified resin and the solid epoxy resin, more preferably 40%-70%, more preferably 50%-65%, more preferably 55%-60%, and most preferably 58%; the curing agent can be a curing agent well known to those skilled in the art, and there is no special restriction. In the present invention, preferably dicyandiamide curing agent, polyamide curing agent, One or more of tertiary amine curing agents, fatty amine curing agents, acid anhydride curing agents and imidazole curing agents; the dicyandiamide curing agent is preferably dicyandiamide; the polyamide curing agent is preferably aliphatic polyamide, aromatic polyamide and urea-formaldehyde polyamide; the tertiary amine curing agent is preferably one or more of imidazole, 1,2-dimethylimidazole, N-acylimidazole, pyridine, 4-dimethylaminopyridine and tetramethylethylenediamine; the fatty amine curing agent is preferably one or more of diethylenetriamine, triethylenetetramine, ethylenediamine and hexamethylenediamine; the acid anhydride curing agent is preferably one or more of tetrahydrophthalic anhydride, hexahydrophthalic anhydride and methylhexahydrophthalic anhydride;The imidazole curing agent is preferably one or more of 2-methylimidazole (2MZ), 2-ethylimidazole (2-EI), 2-ethyl-4-methylimidazole (2E4MZ), 2-undecylimidazole (C11Z), 2-heptadecylimidazole (C17Z), 2-phenylimidazole (2PZ) and 1-benzyl-2-methylimidazole (1B2MZ); the mass of the black particles is preferably 0.1% to 6% of the mass of the black light-transmitting adhesive film layer, more preferably 0.1% to 4%, more preferably 0.3% to 3%, more preferably 0.5% to 2%, more preferably 0.5% to 1%, and most preferably 0.7% to 0.0 .8%; the black particles can be black particles well known to those skilled in the art without any special restrictions. In the present invention, they are preferably one or more of carbon black, graphite, iron black, black quantum dots and black resin; the particle size of the black particles is preferably 3 to 200 nm; optionally, the particle size of the black particles is 3 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm m, 190nm, 200nm or the range between any two of the above values; the mass of the light diffusion particles is preferably 0.1% to 6% of the mass of the black light-transmitting adhesive film layer, more preferably 0.1% to 4%, more preferably 0.3% to 3%, more preferably 0.5% to 2%, more preferably 0.5% to 1%, and most preferably 0.5% to 0.8%; the particle size of the light diffusion particles is preferably 30 to 500nm; optionally, the particle size of the light diffusion particles is 30nm, 50nm, 80nm, 100nm, 120nm, 150nm, 180nm, 200nm, 220nm, 250nm, 280nm, 300nm, 320nm, 350nm, 380nm, 400nm, 420nm, 450nm, 480nm, 500nm or a range between any two of the above values; the light diffusion particles preferably include one or more of silicon dioxide, silicone, titanium dioxide, polymethyl methacrylate, aluminum oxide and polystyrene; in the present invention, the light diffusion particles may further include a modified structure, and the modified structure may be one or more of paraffin coating, silane coupling agent grafting modification and PEG grafting modification; the stability of the light diffusion particles can be improved by modifying the structure. ;

[0044] In another specific embodiment provided by the present invention, the black light-transmitting adhesive film layer preferably further comprises one or more of an epoxy resin catalyst, an antioxidant, a defoaming agent, a hyperdispersant, a silane coupling agent and a diluent solvent; the mass of the epoxy resin catalyst is preferably 5% to 50% of the mass of the black light-transmitting adhesive film layer, more preferably 10% to 40%, more preferably 20% to 40%, more preferably 25% to 35%, and most preferably 30%; the epoxy resin catalyst is preferably one or more of triphenylphosphine, trimethylbenzyl ammonium chloride, trimethylbenzyl ammonium bromide, triethylbenzyl ammonium chloride and triethylbenzyl ammonium bromide; the mass of the antioxidant is preferably 0.1% to 6% of the mass of the black light-transmitting adhesive film layer, more preferably 0.1% to 4%, more preferably 0.3% to 3%, more preferably 0.5% to 2%, more preferably 0.5% to 1%, and most preferably 0.5% to 0.8%; the antioxidant is an antioxidant well known to those skilled in the art, and there is no special limitation. In the present invention, hindered phenol antioxidants and / or phosphite antioxidants are preferred, and more preferably one or more of antioxidants 245, 168, 300, 1010, 1076, 1135, and 1130; the mass of the defoaming agent is preferably 0.1% to 6% of the mass of the black light-transmitting adhesive film layer, more preferably 0.1% to 4%, more preferably 0.3% to 3%, and more preferably 0.5% to 2%. , more preferably 0.5% to 1%, most preferably 0.5% to 0.8%; the defoamer may be any defoamer known to those skilled in the art without any special limitation, and in the present invention, preferably silicone defoamer and / or polyether defoamer, more preferably defoamer BYK-A530; the mass of the hyperdispersant is preferably 0.01% to 6%, more preferably 0.05% to 3%, more preferably 0.1% to 2%, more preferably 0.1% to 1%, most preferably 0.2% to 0.5%; the hyperdispersant may be any hyperdispersant known to those skilled in the art without any particular limitation. In the present invention, it is preferably one or more of an active derivative based on a polyester main chain structure, a polyurethane dispersant, a copolymer of grafted polyacrylate, and a polyether dispersant, and more preferably EFKA-5010, EFKA-4050, EFKA-4060 of Efka, CH-6, CH-7, CH-8 of Shanghai Sanzheng, BYK-2000, BYK-163 of BYK, and BASF PX43 10. One or more of Sichuan Ona F431, Flowlen-33, 34 produced by Kyoeisha, and Tego-650, 651 produced by Degussa; the mass of the silane coupling agent is preferably 0% to 5% of the mass of the black light-transmitting adhesive film layer; the silane coupling agent can be a silane coupling agent well known to those skilled in the art, and there is no special limitation. In the present invention, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyl One or more of methyl dimethoxysilane, N-(2-aminoethyl)-3-aminopropyl methyl dimethoxysilane, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, 3-isocyanate propyl triethoxysilane, 3-isocyanate propyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane (KH570), γ-mercaptopropyl triethoxysilane (KH-580) and γ-mercaptopropyl trimethoxysilane (KH-590); the mass of the dilution solvent is preferably 0% to 1% of the mass of the black light-transmitting adhesive film layer. 0%; the diluent solvent is any diluent solvent known to those skilled in the art, and is not particularly limited. In the present invention, it is preferably one or more of toluene, xylene, n-hexane, ethyl acetate, ethanol, acetone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, ethylene glycol, chloroform, isopropanol, n-butanol, styrene, dibutyl phthalate, dioctyl phthalate, phenyl glycidyl ether, allyl glycidyl ether, p-cresol glycidyl ether, glycidyl methacrylate, ethylene glycol bisglycidyl ether, styrene oxide and alicyclic epoxy. .

[0045] In a specific embodiment provided by the present invention, the light diffusion particles in the black light-transmitting adhesive film layer and the microlens array layer are preferably silicon dioxide. Silicon dioxide can react with both the epoxy resin in the black light-transmitting adhesive film layer and the PDMS in the microlens array layer, thereby enhancing the adhesion of the interface.

[0046] In a specific embodiment provided by the present invention, a silane coupling agent layer is provided between the transparent encapsulation layer and the black light-transmitting adhesive film layer, and the interfacial bonding force between the transparent encapsulation layer and the black light-transmitting adhesive film layer can be improved by providing the silane coupling agent layer; the thickness of the silane coupling agent layer is preferably greater than 10 nm, more preferably greater than 50 nm, and more preferably greater than 100 nm; the silane coupling agent layer is formed by a silane coupling agent; the silane coupling agent can be a silane coupling agent well known to those skilled in the art, and there is no special limitation, and in the present invention, 3-aminopropyltriethoxysilane is preferably used. One or more of alkyl, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane (KH570), γ-mercaptopropyltriethoxysilane (KH-580) and γ-mercaptopropyltrimethoxysilane (KH-590).

[0047] According to the present invention, the surface of the black light-transmitting adhesive film layer away from the substrate is arranged on the microlens array layer; the microlens array layer includes a microlens array base layer and a microlens array arranged on the microlens array base layer; Figure 2 , Figure 2is a schematic diagram of the structure of a microlens array layer, wherein h1 is the diameter of the microlens, h2 is the height of the microlens array, and h3 is the thickness of the microlens array base layer; the microlens array base layer is in contact with the black light-transmitting adhesive film layer; the thickness of the microlens array base layer is preferably 5 to 500 microns; optionally, the thickness of the microlens array base layer is 5 microns, 10 microns, 50 microns, 100 microns, 150 microns, 200 microns, 250 microns, 300 microns, 350 microns, 400 microns, 450 microns, 500 microns, or any two of the above. The microlens array base layer is provided with a microlens array on a surface away from the substrate; the thickness of the microlens array is preferably 3 to 100 microns; optionally, the thickness of the microlens array is 3 microns, 5 microns, 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns or a range between any two of the above values; the microlens array includes a plurality of microlenses; the diameter of the microlens is preferably 3 to 100 microns; optionally, the diameter of the microlens is 3 microns , 5 microns, 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns or a range between any two of the above values; the spacing and arrangement of multiple microlenses can be adjusted according to actual needs; in the present invention, the distance between adjacent microlenses is preferably 1 to 100 microns; optionally, the distance between adjacent microlenses is 1 micron, 5 microns, 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns or a range between any two of the above values; the spacing and arrangement between multiple microlenses can be adjusted according to actual needs; in the present invention, the distance between adjacent microlenses is preferably 1 to 100 microns; optionally, the distance between adjacent microlenses is 1 micron, 5 microns, 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns or a range between any two of the above values 0 micron, 100 micron or the range between any two of the above values; the microlens is a compound eye lens structure; the compound eye lens structure is caused by the micro protrusions formed on the surface of the light diffusion particles after the resin in the microlens array layer is cured and shrunk; the microlens array contains light diffusion particles and is a compound eye lens, and the difference in refractive index between the light diffusion particles and PDMS and their particle size ensures that the light will not be directly emitted from the display module, which has an anti-glare effect and increases the viewing angle; the shape of the microlens can be a cylindrical lens, a spherical mirror, an aspherical lens, a non-cylindrical lens, an astigmatic lens, etc. In the present invention, the microlens is a curved structure, which can effectively reduce the internal total reflection phenomenon when the light is emitted from the module packaging structure into the air, and increase the light extraction efficiency, compared with the flat structure after the existing COB packaging route.

[0048] According to the present invention, the microlens array layer includes resin and light diffusion particles dispersed in the resin; the refractive index of the resin is preferably 1.4-1.5; the refractive index of the light diffusion particles is preferably 1.24-1.55; the refractive index of the microlens array layer is preferably 1.38-1.55; the present invention reduces the refractive index difference of light emitted from the packaging structure to the air (refractive index is 1.0) through the microlens array, increases the critical angle of total reflection, and thus increases the light extraction efficiency. The resin can be any resin well known to those skilled in the art without any special limitation. In the present invention, polydimethylsiloxane (PDMS) is preferably used. In the embodiments provided in the present invention, Dow Corning Sylgard 184 is specifically used as the resin for illustration. The mass of the light diffusion particles is preferably 5% to 60% of the mass of the microlens array layer. Optionally, the mass of the light diffusion particles is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or a range between any two of the above values. The particle size of the light diffusion particles is preferably 30 to 500 nm. Optionally, the particle size of the light diffusion particles is 30 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1500 nm, 2000 nm, 3000 nm, 4000 nm, 5000 nm, 6000 nm, 7000 nm, 8000 nm, 9 ... The light diffusion particles preferably include one or more of silicon dioxide, silicone, titanium dioxide, polymethyl methacrylate, aluminum oxide and polystyrene; in the present invention, the light diffusion particles may further include a modified structure, and the modified structure may be one or more of paraffin coating, silane coupling agent grafting modification and PEG grafting modification; the stability of the light diffusion particles can be improved by modifying the structure.

[0049] In a specific embodiment provided by the present invention, a silane coupling agent layer is provided between the black light-transmitting adhesive film layer and the microlens array layer, and the interfacial bonding force between the black light-transmitting adhesive film layer and the microlens array layer can be improved by providing the silane coupling agent layer; the thickness of the silane coupling agent layer is preferably greater than 10 nm, more preferably greater than 50 nm, and more preferably greater than 100 nm; the silane coupling agent layer is formed by a silane coupling agent; the silane coupling agent can be a silane coupling agent well known to those skilled in the art, and there is no special limitation, and in the present invention, 3-aminopropyltriethoxy is preferred. One or more of silane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane (KH570), γ-mercaptopropyltriethoxysilane (KH-580) and γ-mercaptopropyltrimethoxysilane (KH-590).

[0050] According to the present invention, the overall visible light transmittance of the LED display module is greater than 40%.

[0051] The present invention also provides a method for preparing the above-mentioned LED display module, comprising the following steps: S1) fixing a plurality of LED light-emitting chips on a substrate, and then performing integrated packaging to form a transparent packaging layer; S2) laminating a black light-transmitting adhesive film layer on the transparent packaging layer; S3) coating a resin doped with light-diffusing particles on the surface of the black light-transmitting adhesive film layer, and using a microlens array mold to emboss the microlens array morphology, and after curing, obtaining an LED display module.

[0052] See also Figure 3 , Figure 3 A schematic diagram of the preparation process of the LED display module provided by the present invention.

[0053] According to the present invention, in the step S1), the LED light-emitting chip is fixed by a die bonding wire process.

[0054] According to the present invention, the integrated package preferably uses a dam + molding process; the integrated package is preferably first cured at a high temperature and then cured at room temperature; the high temperature is preferably 100°C to 150°C, more preferably 110°C to 140°C, and more preferably 120°C to 130°C; the curing time at the high temperature is preferably 1 to 10 minutes, more preferably 3 to 6 minutes, and more preferably 5 minutes; the curing time at room temperature is preferably 8 to 20 hours, more preferably 10 to 15 hours, and more preferably 12 hours.

[0055] According to the present invention, it is preferred to first spray a silane coupling agent on the transparent encapsulation layer and dry it before laminating the black light-transmitting adhesive film layer; the silane coupling agent is the same as described above and will not be repeated here; the drying temperature is preferably 60°C to 100°C, more preferably 70°C to 90°C, and more preferably 80°C; the drying time is preferably 10 to 60 minutes, more preferably 20 to 40 minutes, and more preferably 30 minutes.

[0056] According to the present invention, the black light-transmitting adhesive film layer preferably comprises a modified resin, a solid epoxy resin, a curing agent, black particles and light-diffusing particles; specifically, the composition of the black light-transmitting adhesive film layer is the same as described above and will not be repeated here; the black light-transmitting adhesive film layer is preferably prepared according to the following method: A1) after mixing the modified resin with the solid epoxy resin, adding the curing agent, the black particles and the light-diffusing agent to mix, to obtain a black light-transmitting glue; A2) coating the black light-transmitting glue on a release film and drying it to obtain a black light-transmitting adhesive film layer; the modified resin and the solid epoxy resin in A1) are mixed, and then the curing agent, the black particles and the light-diffusing agent are added to obtain a black light-transmitting glue. The temperature of mixing with the epoxy resin is preferably 140°C to 180°C, more preferably 140°C to 160°C, and more preferably 150°C; the coating temperature in step A2) is preferably 60°C to 100°C, more preferably 70°C to 90°C, and more preferably 70°C to 80°C; the coating method is a method well known to those skilled in the art and is not particularly limited. In the present invention, coating is preferably performed using a coater; the drying temperature is preferably 60°C to 100°C, more preferably 70°C to 90°C, and more preferably 70°C to 80°C.

[0057] In a specific embodiment provided by the present invention, the black light-transmitting adhesive film layer is Figure 4 The preparation is carried out according to the process shown.

[0058] According to the present invention, after the black light-transmitting adhesive film layer is adhered, vacuum film pressing and then curing are preferably performed; the curing temperature is preferably 100°C to 150°C, more preferably 110°C to 140°C, more preferably 120°C to 130°C, and most preferably 125°C; the curing time is preferably 50 to 200 min, more preferably 90 to 180 min, and more preferably 150 min.

[0059] According to the present invention, a silane coupling agent is first sprayed on the black light-transmitting adhesive film layer and dried, and then a resin doped with light-diffusing particles is coated on the surface of the black light-transmitting adhesive film layer, and a microlens array morphology is embossed with a microlens array mold. After curing, an LED display module is obtained; the silane coupling agent is the same as described above and will not be repeated here; the drying temperature is preferably 60°C to 100°C, more preferably 70°C to 90°C, and more preferably 80°C; the drying time is preferably 10 to 60 minutes, more preferably 20 to 40 minutes, and more preferably 30 minutes; the resin doped with light-diffusing particles can form a microlens array layer after curing; the light-diffusing particles and the resin in the microlens array layer are the same as described above and will not be repeated here.

[0060] The present invention also provides a display screen, comprising the above-mentioned LED display module.

[0061] In the present invention, unless otherwise specified, parts are parts by weight.

[0062] In order to further illustrate the present invention, an LED display module and a display screen provided by the present invention are described in detail below in conjunction with embodiments.

[0063] The reagents used in the following examples are all commercially available.

[0064] Example 1

[0065] 1.1 Preparation of hot-melt black transparent adhesive film

[0066] The black light-transmitting adhesive film is a silicone-modified epoxy adhesive film, which is prepared from black light-transmitting glue. Its constituent components, calculated by weight, are as follows: 20 parts of solid epoxy resin, 50 parts of liquid silicone-modified epoxy resin, 30 parts of solid silicone-modified epoxy resin, 1.8 parts of carbon black, 1.2 parts of silicon dioxide, 0.5 parts of hyperdispersant, 1.7 parts of defoaming agent, 58 parts of curing agent, 0.5 parts of catalyst, and 1.3 parts of antioxidant.

[0067] The preparation method is as follows:

[0068] S1) respectively weighing solid epoxy resin Nan Ya E-06 (epoxy equivalent of 1500-1800 g / eq), liquid organosilicon-modified epoxy resin complex high-tech EPSI-3201 (epoxy equivalent of 185-205 g / eq), and solid organosilicon-modified epoxy resin Dow Corning EP-2601 into a container, heating to 150° C. with sufficient stirring to prepare a uniform epoxy resin solution with a viscosity of 900 Pa·s;

[0069] S2) add carbon black (Olilong COLOUR BLACK FW200, 13nm), SiO 2(Zhongke Keyou, 100nm), hyperdispersant A163, defoamer BYK-A530, antioxidant 300, curing agent Dyhard100S, catalyst triphenylphosphine, after being configured into a uniform solution, the temperature was controlled to 70°C, vacuum degassing was performed under continuous stirring to prepare black light-transmitting glue, and the glue was maintained at a constant temperature of 70°C;

[0070] S3) using a coating machine to coat it onto a PET release film at a coating temperature of 70° C. and a thickness of 200 μm;

[0071] S4) baking at 80°C for 60 min to obtain a semi-cured hot-melt black transparent adhesive film, which is then cut.

[0072] 1.2 Preparation of LED display screen

[0073] S1) Fixing a number of LED light-emitting chips on the LED driver board by die bonding wire process, with a dot pitch of 0.9 mm, and detecting whether they pass the lighting test;

[0074] S2) using a dam + molding process, after centrifugal degassing of a transparent modified epoxy resin (Kraft K-9761), the surface of the light-emitting chip is packaged in an integrated manner, the thickness of the packaging film is 0.5 mm, and after high-temperature curing at 120° C. for 5 minutes, it is cured at room temperature for 12 hours;

[0075] S3) spraying a layer of silane coupling agent KH570 with a thickness greater than 100 nm on the surface of the cured encapsulation layer, and baking at 80° C. for 30 min;

[0076] S4) placing the cut black transparent adhesive film on the surface of the encapsulation layer, and curing at 125° C. for 150 min after vacuum film pressing;

[0077] S5) spraying a layer of silane coupling agent KH570 with a thickness greater than 100 nm on the surface of the cured black light-transmitting adhesive film layer, and baking at 80° C. for 30 min;

[0078] S6) 40% SiO 2 PDMS (Dow Corning Sylgard 184) is coated on the surface of the black light-transmitting adhesive film layer, and the microlens array morphology is printed with a microlens array mold and cured;

[0079] In the microlens array of this embodiment, the cross-sectional diameter h1 of a single lens is 70 microns, the height h2 is 50 microns, the base height h3 is 300 microns, and the interval between adjacent lenses is 30 microns; the cross-sectional view of the single microlens is as shown in FIG. Figure 5 shown.

[0080] S7) using a dicing machine to cut the process edges of the LED display unit to prepare a standard-sized LED display module.

[0081] The refractive index of the transparent encapsulation layer was measured to be 1.57, the refractive index of the black light-transmitting film layer was 1.49, and the refractive index of the microlens array layer was 1.38.

[0082] Example 2

[0083] The solid epoxy resin E-06 in Example 1 is replaced with GT-6097 (epoxy equivalent is 1500-1800 g / eq) of Huntsman, the liquid silicone modified epoxy resin complex EPSI-3201 is replaced with SEI-7030 (epoxy equivalent is 165 g / eq) of Selvi, the silane coupling agent KH570 is replaced with KH580, and the rest is consistent with Example 1.

[0084] The refractive index of the transparent encapsulation layer was measured to be 1.61, the refractive index of the black light-transmitting film layer was 1.51, and the refractive index of the microlens array layer was 1.38.

[0085] Comparative Example 1

[0086] PDMS without light diffusion particles is coated on the surface of the black light-transmitting adhesive film layer, and a microlens array is embossed with a microlens array mold. Other steps are the same as those in Example 1.

[0087] The refractive index of the transparent encapsulation layer was measured to be 1.57, the refractive index of the black light-transmitting film layer was 1.49, and the refractive index of the microlens array layer was 1.41.

[0088] Comparative Example 2

[0089] After the black light-transmitting adhesive film layer is pressed onto the surface of the transparent encapsulation layer of the LED module and cured, no subsequent treatment is performed, that is, there is no microlens array on the surface, and the rest is the same as in Example 1.

[0090] The refractive index of the transparent encapsulation layer was measured to be 1.57, and the refractive index of the black light-transmitting film layer was measured to be 1.49.

[0091] Comparative Example 3

[0092] The formula of the black light-transmitting adhesive film layer does not contain silicone-modified epoxy resin, and its weight proportion is replaced by liquid epoxy resin E51 (Baling Petrochemical, CYD-128). Others are consistent with Example 1.

[0093] The refractive index of the transparent encapsulation layer was measured to be 1.57, the refractive index of the black light-transmitting film layer was 1.57, and the refractive index of the microlens array layer was 1.38.

[0094] Performance Testing

[0095] Ink color consistency test: Three modules were taken from Example 1, Example 2 and Comparative Example 1 and Comparative Example 2 respectively, and ink color consistency tests were performed. A colorimeter was used to test the L value at 9 different positions of the light board, and the ink color consistency inside the light board and between the light boards was compared. The results are shown in Table 1.

[0096] Table 1 Ink color consistency test results

[0097]

[0098]

[0099] Brightness test: Three modules were taken from Example 1, Example 2 and Comparative Example 1 and Comparative Example 2 respectively. After calibration and passing the aging test, the brightness of each module after lighting was measured using a colorimeter CS-150. The results are shown in Table 2.

[0100] Table 2 Brightness test results of LED display module

[0101]

[0102] It can be seen from the above table that the overall light transmittance of the modules of Example 1 and Example 2 can reach 50% or more; and from the comparison of the data of the above Example 1 and Comparative Example 2, it can be seen that the microlens array can effectively increase the module surface brightness by 29.3%. From the comparison of the data of Comparative Example 1 and Comparative Example 2, it can be seen that the microlens array without light diffusion particles can effectively increase the module surface brightness by 21.5%.

[0103] Adhesion test:

[0104] M1) A copper sheet with the size of 40mm×7.5mm×1mm (length×width×thickness) was selected as the adhesive film carrier. During the test, the bonding area of ​​the two sets of adhesive films was 7.5mm×7.5mm;

[0105] M2) Prepare a black light-transmitting adhesive film according to the method of Example 1 and Comparative Example 3, take 3 copper sheets, coat them with the above two black light-transmitting adhesive films and transparent modified epoxy resin for encapsulation respectively, and cure them, spray a layer of silane coupling agent KH570 after curing, and bake at 80° C. for 30 min;

[0106] M3) Take three copper sheets and coat them with 2% SiO 2 After the curing, the PDMS was bonded to three copper sheets prepared by M2, and the bonding area was 7.5 mm × 7.5 mm.

[0107] M4) Place in an oven at 80°C, bake for 30 minutes, and then cure at room temperature for 24 hours;

[0108] M5) The bonding strength was tested using a testing machine, and the results are shown in Table 3.

[0109] Table 3 Adhesion test results

[0110] Group Adhesion strength (MPa) Example 1 11.82 Comparative Example 3 4.17 Transparent modified epoxy resin for encapsulation 3.93

[0111] From the above results, it can be seen that using silicone-modified epoxy resin to prepare a black light-transmitting adhesive film layer can effectively improve the adhesion between the black light-transmitting adhesive film layer and the microlens array layer.

[0112] In summary, the LED display module provided by the present invention has the following advantages:

[0113] 1) The module can effectively improve the ink color consistency through the black film layer, and can also improve the light output efficiency through the compound eye microlens array, thereby increasing the brightness without increasing the module power. This design has not been seen in existing public patent solutions;

[0114] 2) The resin material of the black light-transmitting film layer is silicone-modified epoxy resin, which plays a good bridging and transition effect between the microlens array (resin material is PDMS) and the encapsulation layer (epoxy resin). The three can form a stable bond through chemical cross-linking, avoiding the occurrence of warping or falling off;

[0115] 3) The silicon dioxide in the black light-transmitting adhesive film layer / microlens array layer can react with both the epoxy resin in the black light-transmitting adhesive film layer and the PDMS in the microlens array layer, thereby enhancing the adhesion of the interface;

[0116] 4) The main component of the encapsulation layer is epoxy resin, whose refractive index is between 1.5 and 1.7, the main component of the black light-transmitting film layer is silicone-modified epoxy resin, whose refractive index is between 1.45 and 1.6, and the comprehensive refractive index of the microlens array is between 1.38 and 1.55 (the light diffusion particles are selected from one or more of silicon dioxide, silicone, PMMA, and PS, whose refractive index is between 1.24 and 1.55, and the refractive index of PDMS is 1.4). The microlens array reduces the refractive index difference of light emitted from the encapsulation structure to the air (refractive index is 1.0), increases the critical angle of total reflection, and thus increases the light extraction efficiency;

[0117] 5) The microlens is a curved structure. Compared with the flat structure after the existing COB packaging route, it can effectively reduce the internal total reflection phenomenon when the light is emitted from the module packaging structure into the air, thereby increasing the light output efficiency;

[0118] 6) The microlens array contains light diffusion particles and is a compound eye lens. The difference in refractive index between the light diffusion particles and PDMS and their particle size ensure that light does not directly escape from the display module, thus achieving an anti-glare effect and increasing the viewing angle.

[0119] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An LED display module, characterized in that: It includes a substrate, a plurality of LED light-emitting chips arranged on the substrate, a transparent packaging layer arranged between the plurality of LED light-emitting chips and on the upper surface thereof, a black light-transmitting adhesive film layer arranged on the transparent packaging layer, and a microlens array layer arranged on the black light-transmitting adhesive film layer; The microlens array layer comprises a microlens array base layer and a microlens array arranged on the microlens array base layer; The microlens array layer includes resin and light diffusion particles dispersed in the resin.

2. The LED display module according to claim 1, characterized in that: The thickness of the microlens array base layer is 5 to 500 microns; The height of the microlens array is 3 to 100 micrometers.

3. The LED display module according to claim 1, characterized in that: The microlens array comprises a plurality of microlenses; the diameter of the microlenses is 3 to 100 microns; the distance between adjacent microlenses is 1 to 100 microns; and / or the microlenses are compound eye lens structures.

4. The LED display module according to claim 1, characterized in that: The mass of the light diffusion particles is 5% to 60% of the mass of the microlens array layer.

5. The LED display module according to claim 1, characterized in that: The resin in the microlens array layer is selected from polydimethylsiloxane; and / or, the light diffusion particles include one or more of silicon dioxide, silicone, titanium dioxide, polymethyl methacrylate, aluminum oxide and polystyrene; And / or, the microlens array layer further includes one or more of a silane coupling agent, a hyperdispersant, a defoaming agent and a diluting solvent.

6. The LED display module according to claim 1, characterized in that: The black light-transmitting adhesive film layer comprises modified resin, solid epoxy resin, curing agent, black particles and light diffusion particles; The modified resin includes silicone-modified epoxy resin and / or epoxy-modified silicone resin; The mass ratio of the modified resin to the solid epoxy resin is 1:1 to 5:

1.

7. The LED display module according to claim 6, characterized in that: The epoxy equivalent of the solid epoxy resin is 1300 to 1950 g / eq; And / or, the mass of the black particles in the black light-transmitting adhesive film layer is 0.1% to 6% of the mass of the black light-transmitting adhesive film layer; And / or, the mass of the light diffusion particles in the black light-transmitting adhesive film layer is 0.1% to 6% of the mass of the black light-transmitting adhesive film layer.

8. The LED display module according to claim 1, characterized in that: The overall visible light transmittance of the LED display module is greater than 40%; And / or, the thickness of the black light-transmitting adhesive film layer is 5 to 300 microns; And / or, the visible light transmittance of the black light-transmitting adhesive film layer is greater than 35%; And / or, a silane coupling agent layer is provided between the transparent encapsulation layer and the black light-transmitting adhesive film layer and / or between the black light-transmitting adhesive film layer and the microlens array layer.

9. The LED display module according to claim 1, characterized in that: The refractive index of the transparent encapsulation layer is 1.5 to 1.7; And / or, the refractive index of the black light-transmitting adhesive film layer is 1.45 to 1.6; And / or, the refractive index of the microlens array layer is 1.38-1.

55.

10. A display screen, characterized in that: The LED display module comprises any one of claims 1 to 9.

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