Diffusion plate for use in backlight module with low optical path distance
Patent Information
- Application Number
- TW113100310
- Authority / Receiving Office
- TW · TW
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-12-22
- Publication Date
- 2026-07-11
- Estimated Expiration
- 2042-12-21
Smart Images
Figure IMG-2_DRAW_113100310-A0305-14-0005-1 
Figure IMG-2_DRAW_113100310-A0101-14-0001-10 
Figure IMG-2_DRAW_113100310-A0101-14-0002-11
Abstract
Description
Technical Field
[0001] This invention relates to a diffuser plate for use in a low optical path distance backlight module, and more particularly to a diffuser plate that can be assembled onto a backlight module and still provide good light diffusion function at low optical path distance, thereby achieving the effect of blocking MURA (bright and dark bands) to generate a uniform surface light source. Prior Technology
[0002] With the development of backlit displays, and the trend towards thinner designs, backlight modules inevitably face the need for ultra-thin designs as well. As the optical distance (OD) of the backlight module decreases, the light intensity increases, but the MURA (Mullion-Range Amplitude) decreases. Therefore, if traditional diffuser plates continue to be used in low-optical-distance backlight modules, their light diffusion effect will no longer meet the requirements.
[0003] Furthermore, there are two main types of light-emitting diodes (LEDs) used in traditional backlight displays: one type uses blue LEDs to excite yellow phosphors, with the two colors mixing to produce white light; the other type uses LEDs with three primary colors to mix and produce white light. However, the color gamut of backlight displays using these two types of light sources is relatively low, resulting in insufficient color performance.
[0004] Currently, backlit displays use blue LEDs to excite green and red quantum dots, with the three lights mixing to create white light, increasing the color gamut to 120% NTSC. However, this type of backlit display still has the following drawbacks. First, quantum dots are easily affected by moisture and oxygen, reducing or even eliminating their activity. Prolonged use can lead to quantum dot failure, causing abnormal color display. Second, the blue LEDs excite green and red quantum dots, and the mixing of blue, green, and red light to create white light requires consistent light intensity to avoid insufficient red / green light conversion. However, because the ambient light intensity is lower than the center light intensity, a bluish tint appears around the edges, resulting in inconsistent colors. Furthermore, most existing quantum dot films use a surface-mounted water and gas barrier to block moisture and oxygen. However, this method only blocks moisture and oxygen entering the quantum dot film from the top surface, not from the sides. Therefore, after a period of use, the four sides of the quantum dot film in the backlight display will still be affected by moisture and oxygen intrusion, causing the quantum dots to fail and resulting in abnormal colors in the four edges of the backlight display. Although some manufacturers have tried to apply a protective coating to all four sides of the quantum dot film in the backlight display, this method requires multiple processing steps, which is complicated, costly, and has a low yield.
[0005] Therefore, the present invention provides a diffuser plate for use in a backlight module with a low optical path distance, which can be assembled into a backlight module and still provide good light diffusion function at a low optical path distance, thereby achieving the goal of blocking MURA (bright and dark bands) to generate a uniform surface light source. Summary of the Invention
[0006] The main objective of this invention is to provide a diffuser plate for use in low optical path distance backlight modules. Different diffusion particle additives are added to the surface layer and mainboard layer of the diffuser plate, which is then extruded using a foaming technique. By varying the refractive indices and amounts of the original resin material, microbubbles, and diffusion particle additives in the surface layer and mainboard layer of the diffuser plate, the refractive indices of the upper and lower surface layers are substantially greater than those of the mainboard layer. This allows for more effective diffusion of light emitted from the lower light source, resulting in a better MURA (muzzle-proof) effect and the creation of a uniform surface light source.
[0007] Another objective of this invention is to provide a diffuser plate that can be assembled onto a backlight module using a blue light-emitting diode (LED) as the light source. A plurality of microstructures with a plurality of recesses and protrusions are formed on the surface of the diffuser plate. A quantum dot layer containing a plurality of green quantum dots and a plurality of red quantum dots is coated into the recesses of the microstructures. A water- and gas-barrier layer is then disposed on the upper surface of the quantum dot layer. By using the plurality of protrusions of the microstructures to separate the quantum dot layers located within the recesses, making each layer independent, external moisture and oxygen cannot penetrate the four sides of the quantum dot layer and invade the entire quantum dot layer. This method offers advantages such as simple manufacturing process, low cost, and high production yield.
[0008] To achieve the above objectives, this invention discloses a diffuser plate for use in a low optical path distance backlight module, which can be assembled onto a backlight module. The backlight module includes: a substrate and a plurality of light-emitting elements arranged in an array on the substrate; the diffuser plate is located above the substrate and includes:
[0009] A board having an upper surface and a lower surface, the lower surface facing the substrate; the board is a multilayer structure formed by coextrusion, comprising a main board layer, an upper surface layer, and a lower surface layer; the upper surface layer is laminated to the side of the main board layer facing the upper surface, and the lower surface layer is laminated to the side of the main board layer facing the lower surface;
[0010] A first diffusion particle additive is added to the motherboard layer; the first diffusion particle additive comprises a plurality of first diffusion particles; the weight percentage of the added first diffusion particle additive in the motherboard layer is a first weight percentage; each first diffusion particle has a first material refractive index; and
[0011] A second diffusion particle additive is added to the upper surface layer and the lower surface layer; the second diffusion particle additive comprises a plurality of second diffusion particles; the weight percentage of the added second diffusion particle additive in the upper surface layer and the lower surface layer is a second weight percentage; each second diffusion particle has a second material refractive index;
[0012] The diffuser plate meets at least one of the following two conditions:
[0013] Condition 1: The refractive index of the first material in the first diffusing particle is less than the refractive index of the second material in the second diffusing particle;
[0014] Condition 2: The first weight percentage of the first diffusion particle additive is less than the second weight percentage of the second diffusion particle additive.
[0015] In one embodiment, the material of the plate includes one of the following: polycarbonate (PC), polystyrene (PS), polymethyl methacrylate (PMMA, commonly known as acrylic), polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET).
[0016] In one embodiment, the plurality of first diffused particles included in the first diffused particle additive include one of the following: silicone beads, acrylic beads, polystyrene beads, and acrylic-polystyrene copolymer beads; wherein the particle size of the first diffused particles is between 1 and 4 μm, the refractive index of the first material is between 1.42 and 1.5, and the first weight percentage of the first diffused particle additive added to the main board layer is between 1 and 4%.
[0017] In one embodiment, the plurality of second diffusion particles contained in the second diffusion particle additive include one of the following inorganic particles: calcium carbonate, barium sulfate, titanium oxide, talc, mica, and boron nitride; wherein the particle size of the second diffusion particles is between 0.05 and 8 μm, the refractive index of the second material is between 1.5 and 2.6, and the second weight percentage of the second diffusion particle additive added to the upper and lower surface layers is between 0.1 and 1.5%.
[0018] In one embodiment, the plurality of second diffused particles included in the second diffused particle additive include one of the following: silicone beads, acrylic beads, polystyrene beads, and acrylic-polystyrene copolymer beads; wherein the particle size of the second diffused particles is between 15 and 25 μm, the refractive index of the second material is between 1.42 and 1.5, and the second weight percentage of the second diffused particle additive added to the upper and lower surface layers is between 5 and 10%; wherein the second weight percentage is greater than the first weight percentage, and the particle size of the second diffused particles is greater than the particle size of the first diffused particles.
[0019] In one embodiment, the diffuser plate further includes:
[0020] A plurality of microstructures are arranged in an array on at least the upper surface of the plate; and
[0021] An optical film is attached to the upper surface of the plate by means of an optical adhesive; wherein the thickness of the optical film is between 5 and 20 μm.
[0022] In one embodiment, the diffuser plate further includes:
[0023] A plurality of microstructures are arranged in an array on at least the lower surface of the plate.
[0024] An optical film is attached to the lower surface of the plate by means of an optical adhesive; and
[0025] A reflective film is attached to the lower side of the lower optical film; wherein, the reflectivity of the reflective film for light with a wavelength below 500 nm is < 20%, and the reflectivity of the reflective film for light with a wavelength above 500 nm is > 90%.
[0026] In an embodiment, the diffuser plate further includes:
[0027] A plurality of microstructures, arranged in an array on at least the upper surface of the plate body; a plurality of the microstructures form a plurality of convex portions and a plurality of concave portions on the upper surface of the plate body, and the plurality of concave portions are separated by the plurality of convex portions, so the plurality of concave portions are independent of each other and do not communicate with each other;
[0028] A quantum dot layer is arranged at the plurality of concave portions on the upper surface of the plate body; wherein, the thickness of the quantum dot layer is t1, the distance from the top of a plurality of the convex portions to the bottom of a plurality of the concave portions is t2, and t1 < t2; and
[0029] A water and gas barrier layer is arranged on the upper surface of the plate body and covers the plurality of convex portions and the quantum dot layer.
[0030] [[ID=第十九]] In an embodiment, a plurality of the microstructures, the quantum dot layer, and the water and gas barrier layer are also arranged on the lower surface of the plate body; a plurality of the microstructures form a plurality of the convex portions and a plurality of the concave portions on the lower surface of the plate body, and the plurality of concave portions are separated by the plurality of convex portions, so the plurality of concave portions on the lower surface of the plate body are independent of each other and do not communicate with each other; and, the quantum dot layer located on the lower surface of the plate body is arranged at the plurality of concave portions on the lower surface of the plate body; in addition, the water and gas barrier layer on the lower surface of the plate body covers the plurality of convex portions and the quantum dot layer on the lower surface of the plate body.
[0031] In an embodiment, the quantum dot layer contains a plurality of quantum dots (Quantum Dot; hereinafter referred to as QD); the plurality of quantum dots are a kind of nanocrystal semiconductor material composed of II-VI, III-V, or IV-VI group elements, and the grain diameter of each quantum dot is between 2 and 10 nm; wherein, the plurality of quantum dots include a plurality of green quantum dots with an emission wavelength of 520 - 530 nm and a plurality of red quantum dots with an emission wavelength of 620 - 630 nm.
[0032] In one embodiment, the plurality of microstructures comprises a plurality of N-sided pyramids, where N is a positive integer greater than or equal to three; t2 is between 6 and 200 μm; and the thickness of the water- and gas-barrier layer is t3, which is between 5 and 100 μm.
[0033] In one embodiment, t2 is between 25 and 50 μm, t1 is between 10 and 40 μm, and t3 is between 10 and 30 μm.
[0034] In one embodiment, the maximum width of the protrusion is between 50 and 500 μm, and the distance between two adjacent protrusions is between 50 and 1000 μm.
[0035] In one embodiment, the main board layer of the board is formed by foam extrusion molding, and the main board layer contains a plurality of microbubbles; the weight reduction rate of the plurality of microbubbles to the main board layer is between 15% and 25%, and the average size of the plurality of microbubbles is between 60 and 800 μm;
[0036] The formula for calculating the weight loss rate is as follows:
[0037] Weight loss rate (%) = (W1 - W2) / W2 * 100%
[0038] W1=H*(L1*L2*D)
[0039] in:
[0040] H is the average thickness (mm) of the motherboard layer;
[0041] L1 is the length of the mainboard layer (mm);
[0042] L2 is the width of this motherboard layer (mm);
[0043] D is the specific gravity of the raw material in this motherboard layer (g / mm3);
[0044] W1 is the theoretical weight (g) of this motherboard layer, which is the weight excluding the multiple microbubbles.
[0045] W2 is the actual weight (g) of the mainboard layer, which is the actual weight of the mainboard layer containing multiple microbubbles as measured by a scale.
[0046] In one embodiment, a plurality of the microbubbles are generated by adding a foaming agent and a nucleating agent during the foaming extrusion molding process of the main board layer; the nucleating agent comprises at least one of the following: calcium carbonate, silicon dioxide, calcium oxide; and the weight percentage of the added nucleating agent is 0.1%-0.5%. Simple Explanation of the Diagram
[0047]
[0048] Figure 1 is a cross-sectional schematic diagram of the first embodiment of the present invention, in which a diffuser plate for a low optical path distance backlight module is installed in a backlight module and combined with a liquid crystal panel to form a backlight display.
[0049] Figures 2A, 2B, and 2C are schematic diagrams of three different embodiments of the microstructures provided on the upper and lower surfaces of the diffusion plate of the present invention.
[0050] Figure 3 is a cross-sectional schematic diagram of a second embodiment of the present invention, in which a diffuser plate for a low optical path distance backlight module is installed in a backlight module and combined with a liquid crystal panel to form a backlight display.
[0051] Figure 4 is a cross-sectional schematic diagram of the third embodiment of the present invention, in which a diffuser plate for a low optical path distance backlight module is installed in a backlight module and combined with a liquid crystal panel to form a backlight display.
[0052] Figure 5 is a graph showing the different reflectivities of the reflective film of the present invention for light of different wavelengths.
[0053] Figures 6 and 7 are respectively a cross-sectional view and an exploded three-dimensional view of the fourth embodiment of the present invention, in which the diffuser plate of the present invention is installed in a backlight module with a low optical path distance.
[0054] Figure 8 is a cross-sectional schematic diagram of the fifth embodiment of the present invention, in which the diffuser plate of the present invention is installed in a backlight module for a low optical path distance backlight module. Implementation
[0055] This invention relates to a diffuser plate for use in low optical path distance backlight modules. Different diffusion particle additives are added to the upper and lower surface layers and the main board layer of the diffuser plate, which are then co-extruded into a multi-layer diffuser plate using a foaming technique. By varying the refractive indices and amounts of the original resin material, microbubbles, and diffusion particle additives in the two surface layers and the main board layer, the refractive indices of the upper and lower surface layers are substantially greater than those of the main board layer. Consequently, some of the light emitted from the lower light source is refracted or reflected back and forth between the two surface layers and the main board layer after entering the diffuser plate, achieving a more effective light diffusion effect and thus achieving MURA (mullion beam) shielding to produce a uniform surface light source.
[0056] To more clearly describe the diffuser plate and its manufacturing method for use in low optical path distance backlight modules proposed in this invention, the following detailed description will be provided in conjunction with the accompanying drawings.
[0057] Please refer to Figure 1, which is a cross-sectional schematic diagram of a first embodiment of the present invention, in which a diffuser plate for a low optical path distance backlight module is mounted in a backlight module and combined with a liquid crystal panel to form a backlight display. The backlight module of the present invention is mounted below a liquid crystal panel 93 to form a backlight display. In this first embodiment, the backlight module includes, from bottom to top, a substrate 91, a plurality of light-emitting elements 92, and a diffuser plate. A circuit layout (not shown) is provided on the substrate 91. The plurality of light-emitting elements 92 are arranged in an array on the top surface 911 of the substrate 91 and electrically coupled to the circuit layout. In this embodiment, these light-emitting elements 92 are blue light-emitting diodes (LEDs) that emit blue light upwards toward the diffuser plate 10. These light-emitting elements 92 can be conventional blue LEDs, blue Mini LEDs, or even blue Micro LEDs. A reflective layer is provided on the top surface 911 of the substrate 91. The reflective layer can be white or other colors or surfaces with better light reflection effects, and is used to reflect light upwards toward the diffuser plate 10.
[0058] The diffuser plate 10 is located above and adjacent to the plurality of light-emitting elements 92 on the substrate 91, and generally there are no other elements between the diffuser plate 10 and the light-emitting elements 92 disposed on the substrate 91. In this invention, the diffuser plate includes: a plate 10, a first diffusion particle additive, a second diffusion particle additive, a plurality of microbubbles 1012, and a plurality of microstructures 1022 and 1032. The plate 10 has an upper surface and a lower surface. The lower surface of the plate 10 faces the substrate 91 and serves as the light-incident surface; light emitted by the light-emitting elements 92 enters the plate 10 through the lower surface (light-incident surface). Conversely, the upper surface of the plate 10 is the light-emitting surface; light entering the plate 10 is refracted and diffused, and then emitted from the upper surface (light-emitting surface) of the plate 10 and directed towards the liquid crystal panel 93 located above. The board 10 is a multilayer board structure formed by coextrusion, comprising a main board layer 101, an upper surface layer 102, and a lower surface layer 103. The upper surface layer 102 is laminated to the side of the main board layer 101 facing the upper surface, and the lower surface layer 103 is laminated to the side of the main board layer 101 facing the lower surface. The substrate of the board 10 may be an amorphous or semi-crystalline organic polymer plasticizing material, comprising one of the following: polycarbonate (PC), polystyrene (PS), polymethyl methacrylate (PMMA, commonly known as acrylic), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or a copolymer of any of the aforementioned materials. In this embodiment, the thickness ratio of the motherboard layer 101 to the total thickness of the two surface layers 102 and 103 (the sum of the thicknesses of the upper and lower surface layers) can be implemented within a range of 9.5:0.5 to 1:1, with a preferred range of 9:1 to 7:3. The substrates of the motherboard layer 101 and the two surface layers 102 and 103 can be the same material or different materials.
[0059] In this embodiment, the first diffusion particle additive comprises a plurality of first diffusion particles 1011, which are added to the main board layer 101. The weight percentage of the added first diffusion particle additive in the main board layer 101 is a first weight percentage; each first diffusion particle 1011 has a first material refractive index. The second diffusion particle additive comprises a plurality of second diffusion particles 1021 and 1031, which are added to the upper surface layer 102 and the lower surface layer 103, respectively. The weight percentage of the added second diffusion particle additive in the upper surface layer 102 and the lower surface layer 103 is a second weight percentage; each second diffusion particle 1021 and 1031 has a second material refractive index. The technical feature of the present invention is that the diffusion plate meets at least one of the following two conditions:
[0060] Condition 1: The refractive index of the first material of the first diffusing particle 1011 is less than the refractive index of the second material of the second diffusing particles 1021 and 1031;
[0061] Condition 2: The first weight percentage of the first diffusion particle additive is less than the second weight percentage of the second diffusion particle additive.
[0062] By satisfying one, two, or both of the above conditions, the refractive indices of the upper and lower surface layers 102 and 103, which contain a plurality of second diffuser particles 1021 and 1031 with relatively high refractive indices and / or a concentration (by weight percentage), can be substantially higher than the refractive index of the mainboard layer 101, which contains a plurality of first diffuser particles 1011 with relatively low refractive indices and / or a concentration (by weight percentage). This results in the upper and lower surface layers 102 and 103 providing a slight reflection effect on the side facing the mainboard layer 101. Therefore, after the light emitted by the light-emitting element 92 enters the interior of the plate 10, a portion of the light is refracted or reflected several times within the mainboard layer 101 between the upper and lower surface layers 102 and 103 before being emitted from the upper surface (light-emitting surface). This increases the number of refractions or reflections of the light, thus achieving a more effective diffusion effect and enhancing the shielding effect of MURA to produce a uniform surface light source.
[0063] In this embodiment, the plurality of first diffusion particles 1011 included in the first diffusion particle additive comprises at least one of the following polymeric material diffusion particles: silicone beads, acrylic beads, polystyrene beads, and acrylic-polystyrene copolymer beads (PMMA-PS beads). The particle size of the first diffusion particles 1011 is preferably between 0.5 and 10 μm, but between 1 and 4 μm. The refractive index of the first material is between 1.42 and 1.5. The first weight percentage of the first diffusion particle additive added to the mainboard layer 101 is preferably between 0.5 and 10%, but between 1 and 4%. Both the first and second diffusion particle additives described herein are commercially available and known products.
[0064] In this invention, the plurality of second diffusion particles 1021 and 1031 contained in the second diffusion particle additive can have two embodiments: the first is inorganic diffusion particles, and the second is polymeric material diffusion particles. In the first embodiment, the plurality of second diffusion particles 1021 and 1031 contained in the second diffusion particle additive can contain at least one of the following inorganic particles: calcium carbonate, barium sulfate, titanium dioxide, talc, mica, and boron nitride; wherein, the particle size of the second diffusion particles 1021 and 1031 is preferably between 0.01 and 10 μm, but preferably between 0.05 and 8 μm; the refractive index of the second material is between 1.5 and 2.6; and the second weight percentage of the second diffusion particle additive added to the upper surface layer 102 and the lower surface layer 103 is preferably between 0.1 and 3%, but preferably between 0.1 and 1.5%. In the second embodiment, the plurality of second diffusion particles 1021, 1031 included in the second diffusion particle additive comprises at least one of the following polymer diffusion particles: silicone beads, acrylic beads, polystyrene beads, and acrylic-polystyrene copolymer beads (PMMA-PS). (beads); wherein, the particle size of the second diffusing particles 1021 and 1031 is preferably between 10 and 50 μm, but between 15 and 25 μm; the refractive index of the second material is between 1.42 and 1.5; the second weight percentage of the second diffusing particle additive added to the upper surface layer 102 and the lower surface layer 103 is preferably between 1 and 20%, but between 5 and 10%; and, in this second embodiment, the second weight percentage must be greater than the first weight percentage, and the particle size of the second diffusing particles 1021 and 1031 is greater than the particle size of the first diffusing particle 1011. By using the second diffusion particle additive defined in the first and second embodiments to complement the first diffusion particle additive defined above, it can be ensured that the refractive index of the upper and lower surface layers 102 and 103 is substantially higher than the refractive index of the motherboard layer 101, thereby achieving the effects of more effectively diffusing light, enhancing the shielding of MURA, and generating a uniform surface light source.
[0065] As shown in Figure 1, in the first embodiment of the diffuser plate of the present invention, a plurality of microstructures 1022 and 1032 are respectively arranged in an array on the upper and lower surfaces of the plate body 10, which can further improve the light diffusion effect of the diffuser plate. Furthermore, the main plate layer 101 of the plate body 10 is formed by foam extrusion molding, and the main plate layer 101 contains a plurality of microbubbles 1012. The weight reduction rate of the plurality of microbubbles 1012 on the main plate layer 101 can be implemented in the range of 5% to 30%, but a weight reduction rate of 10% to 20% is preferred, and the average size of the plurality of microbubbles 1012 is between 60 and 800 μm; wherein, the formula for calculating the weight reduction rate is:
[0066] Weight loss rate (%) = (W1 - W2) / W2 * 100%;
[0067] W1 = H * (L1 * L2 * D);
[0068] in:
[0069] H is the average thickness (mm) of the motherboard layer;
[0070] L1 is the length of the mainboard layer (mm);
[0071] L2 is the width of this motherboard layer (mm);
[0072] D is the specific gravity of the raw material in this motherboard layer (g / mm3);
[0073] W1 is the theoretical weight (g) of this motherboard layer, which is the weight excluding the multiple microbubbles.
[0074] W2 is the actual weight (g) of the mainboard layer, which is the actual weight of the mainboard layer containing multiple microbubbles as measured by a scale.
[0075] In this embodiment, a plurality of microbubbles 1012 are generated by adding an appropriate amount of a foaming agent and a nucleating agent during the foaming extrusion molding process of the main board layer 101; the nucleating agent comprises at least one of the following: calcium carbonate, silicon dioxide, and calcium oxide; the weight percentage of the added nucleating agent can be in the range of 0.01%-5%, but is preferably in the range of 0.1%-0.5%. The weight loss rate of the microbubbles 1012 can be controlled by the amount of foaming agent added, and the bubble diameter of the microbubbles 1012 can be controlled by adding nucleating agent and adjusting the process temperature. The process temperature of the foaming co-extrusion process of the multilayer board 10 of the diffusion plate of the present invention is adjusted according to the different types of raw material resin and foaming agent. The processing temperature of the present invention is the general polycarbonate processing temperature, preferably 220~270°C.
[0076] Please refer to Figures 2A, 2B, and 2C, which are schematic diagrams of three different embodiments of the microstructures provided on the upper and lower surfaces of the diffuser plate of the present invention. The diffuser plate of the present invention uses an extrusion process to extrude a plurality of microstructures 1022 and 1032 onto the upper and lower surfaces of the plate body. These microstructures 1022 and 1032 have a plurality of protrusions or concave portions, and their protrusions and concavities can be regularly or irregularly distributed on the upper and lower surfaces of the diffuser plate body 10. In a top view, these microstructures 1022 and 1032 can be circular, amoeba-like (as shown in Figure 2A), irregularly frosted (as shown in Figure 2B), pyramidal (as shown in Figure 2C), etc., with the best overall brightness enhancement achieved when the light-incident surface of the plate body 10 is mirror-like (without microstructures and a smooth surface) and the light-emitting surface is provided with pyramidal microstructures.
[0077] In the other embodiments of the present invention described below, since most of the components and functions are the same as those in the first embodiment, the same or similar components will be given the same names and numbers, and their details will not be repeated.
[0078] Please refer to Figure 3, which is a cross-sectional schematic diagram of a second embodiment of the present invention, in which a diffuser plate for a low optical path distance backlight module is installed in a backlight module and combined with a liquid crystal panel to form a backlight display. In the second embodiment, the backlight module also includes, from bottom to top, a substrate 91, a plurality of light-emitting elements 92, and a diffuser plate. The diffuser plate is located above the substrate 91 and also includes: a plate body 10 (including a main plate layer 101, an upper surface layer 102, and a lower surface layer 103), a first diffusion particle additive (including first diffusion particles 1011), a second diffusion particle additive (including second diffusion particles 1021 and 1031), a plurality of microbubbles 1012, and a plurality of microstructures 1022 and 1032. Since most of the components, structures, and functions of the diffuser plate in the second embodiment shown in Figure 3 are the same as or similar to those in the first embodiment shown in Figure 1, the details of these same or similar components will not be repeated. The difference from the first embodiment described above is that, in the second embodiment shown in FIG. 3, the diffuser plate further includes an upper optical film 15, which is attached to the upper surface of the plate 10 by an optical adhesive 151; wherein, the thickness of the optical adhesive 151 is between 5 and 20 μm, and both the optical adhesive 151 and the upper optical film 15 are commercially available known products. The optical adhesive 151 serves as an adhesive medium for bonding the upper optical film 15 to the upper surface of the plate 10. The upper optical film 15 provides a color conversion function that converts blue light into white light and is a commercially available known product. Therefore, the present invention can use a blue light-emitting diode as a light-emitting element 92, and convert it into uniform white light by the diffuser plate and the upper optical film 15 attached to the upper surface of the plate 10, providing the function of a white light backlight module.
[0079] Please refer to Figure 4, which is a cross-sectional schematic diagram of the third embodiment of the present invention, in which a diffuser plate for a low optical path distance backlight module is installed in a backlight module and combined with a liquid crystal panel to form a backlight display. In the third embodiment, the backlight module also includes, from bottom to top, a substrate 91, a plurality of light-emitting elements 92, and a diffuser plate. The diffuser plate is located above the substrate 91 and also includes: a plate body 10 (including a main plate layer 101, an upper surface layer 102, and a lower surface layer 103), a first diffusion particle additive (including first diffusion particles 1011), a second diffusion particle additive (including second diffusion particles 1021 and 1031), a plurality of microbubbles 1012, and a plurality of microstructures 1022 and 1032. Since most of the components, structures, and functions of the diffuser plate in the second embodiment shown in Figure 3 are the same as or similar to those in the second embodiment shown in Figure 2, the details of these same or similar components will not be repeated. The difference from the second embodiment described above is that, in the third embodiment shown in FIG4, the diffuser plate further includes a lower optical film 15 and a reflective film 152, which are attached to the lower surface of the plate 10 by an optical adhesive 151; wherein, the thickness of the optical adhesive 151 is between 5 and 20 μm; the reflective film 152 is attached below the lower optical film 15. The optical adhesive 151, the lower optical film 15, and the reflective film 152 are all commercially available known products. The optical adhesive 151 serves as an adhesive medium for bonding the lower optical film 15 and the reflective film 152 to the lower surface of the plate 10. The lower optical film 15 provides a color conversion function that converts blue light into white light. FIG5 shows a graph of the different reflectivities of the reflective film of the present invention for different wavelengths of light. As shown in Figure 5, the reflective film 152 has a reflectivity of <20% for light with wavelengths below 500nm and a reflectivity of >90% for light with wavelengths above 500nm. In other words, the blue light emitted by the lower blue light-emitting diode can pass smoothly through the reflective film 152 and the lower optical film 15 before entering the interior of the plate 10. Conversely, the light converted into white light by the lower optical film 15 cannot pass downward through the reflective film 152, but is reflected by the reflective film 152 and emitted upward toward the upper surface of the plate 10. Therefore, this invention can use a blue light-emitting diode as the light-emitting element 92, and the diffuser plate and the lower optical film 15 and reflective film 152 adhered to the lower surface of the plate 10 convert it into uniform white light before it is emitted upward, providing the function of a white backlight module.
[0080] Based on the aforementioned technical concept, this invention fabricated several different diffusion plates for testing. Each diffusion plate was given different structural or material parameters, including: the particle size, refractive index, and amount of diffusing particles added to the main body layer and the two surface layers; the materials of the main body layer and the two surface layers; the thickness ratio of the two surface layers to the main body layer relative to the plate body; the presence and type of surface microstructures; whether the main body layer generated microbubbles through a foaming process and the bubble diameter of these microbubbles; whether the light-emitting surface (upper surface of the plate body) has an optical film and optical adhesive, and the thickness of the optical adhesive; whether the light-receiving surface (lower surface of the plate body) has a reflective film, etc. Then, the optical effects (including: luminance, light diffusion, mura, tint, etc.) of these diffusion plates with different parameters were tested or observed one by one, and these optical effects were analyzed and compared. The results are then summarized in Tables 1 to 6 below.
[0081] In Tables 1 to 6 below, the columns "Particle Size," "Refractive Index," and "Amount Added" refer to the particle size, refractive index, and amount (by weight) of the multiple diffusion particles contained in the diffusion particle additive added to the upper, main, or lower layers of the diffuser plate, respectively. The "Thickness Ratio" column refers to the ratio of the thickness of the upper, main, or lower layer to the total thickness of the plate. The "Material" column refers to the substrate material of the upper, main, or lower layer; PS refers to polystyrene, and MS refers to methyl methacrylate. The "Surface Structure" column indicates whether microstructures are present on the upper (light-emitting) or lower (light-receiving) surface of the plate, and the type of microstructure (in this column, "Frost" indicates an irregular frosted microstructure, and "Pyramid" indicates a pyramid-shaped microstructure). The "Foaming Process" column indicates whether microbubbles are generated in the main layer through a foaming process, and the size of these microbubbles. The "Optical Film" field indicates whether an optical film is adhered to the upper surface (light-emitting surface) of the board using optical adhesive, and the thickness of the optical adhesive. The "Reflective Film" field indicates whether a reflective film is applied to the lower surface (light-receiving surface) of the board. The parameters are: "Luminosity (%)", "Light Diffusion (%)", "Mura (values range from 1 to 5, where 1 indicates the most severe mura and 5 indicates the mildest mura and therefore the best optical performance)", and "Optical Quality (values range from 1 to 5, where 1 indicates the worst visual optical quality and 5 indicates the best quality)".
[0082] Table 1 shows the structure and material information of the comparative examples and embodiments of the diffusion plates tested. As can be seen from Table 1, the diffusion plates of Comparative Examples 1 and 2 have the same particle size, refractive index, and amount of the multiple diffusion particles added to both surface layers and the main body layer. Therefore, they are comparative examples of diffusion plates manufactured according to prior art. In contrast, in the diffusion plates of Embodiments 1-6, at least one of the particle size, refractive index, and amount of the multiple diffusion particles added to both surface layers is greater than that of the diffusion particles added to the main body layer, resulting in a higher refractive index on both surface layers than on the main body layer. Therefore, these are diffusion plates manufactured according to the aforementioned technical concept of the present invention. That is, in Tables 1 to 6, Comparative Examples 1 and 2 are diffusion plates manufactured according to prior art, while Embodiments 1-6 are diffusion plates manufactured according to the aforementioned technical concept of the present invention.
[0083] Table 1: List of structural and material information for each comparative example and embodiment of the diffuser plate tested.
[0084]
[0085] In Table 2 below, diffusion particle additives were added to the main body layer of the diffusion plates in Examples 1, 2, 2-1, 3, and 3-1. In some examples, microbubbles were formed in the main body layer through a foaming process. Both the upper and lower surfaces of the diffusion plates in each example contained diffusion particle additives with relatively high particle size, refractive index, or dosage. In Example 2, the diffusion particles added to the upper and lower surfaces were inorganic additives, and the refractive index of the inorganic diffusion particles in the two surface layers was greater than that of the diffusion particles contained in the additives in the main body layer. In Example 3, the diffusion particles added to the upper and lower surfaces were organic additives (i.e., polymeric plasticizer additives), and the refractive index of the organic diffusion particles in the two surface layers was greater than that of the diffusion particles contained in the additives in the main body layer. The structures and materials of Examples 2-1 and 3-1 generally correspond to Examples 2 and 3, respectively, except that Examples 2-1 and 3-1 further increased the concentration (dosage) of the additives in the upper and lower surfaces. As shown in Table 2, Examples 1, 2, 2-1, 3, and 3-1 exhibit significantly higher optical performance than Comparative Examples 1 and 2 in terms of luminance, light diffusion, and Mura. Furthermore, the luminance performance of Example 2-1 is worse than that of Example 2, and the luminance performance of Example 3-1 is also worse than that of Example 3, demonstrating that luminance decreases when the concentration of additives in the upper and lower surface layers increases.
[0086] Table 2: Comparison of diffusing particles with different particle sizes, refractive indices, or amounts added to the two outer layers and the main body of the diffuser plate.
[0087]
[0088] In Table 3 below, both the upper and lower surfaces of Example 3 were provided with a hazy microstructure, while both the upper and lower surfaces of Example 4 were provided with a pyramidal microstructure. Comparative Examples 1 and 2 did not have any microstructures. As can be seen from Table 3, Example 4, which has a pyramidal microstructure, has a higher luminance than Example 3, while the MURA performance of light diffusion is the same for both, proving that a pyramidal surface microstructure can have a higher luminance than a hazy microstructure.
[0089] Table 3: Comparison of different surface microstructures on the light-incident and light-exit surfaces of the diffuser plate
[0090] In Table 4 below, the diffusion plates of Examples 3, 5, and 6 have mainboard layers and two surface layers with different materials or different thickness ratios. As shown in Table 4, the ratio of the mainboard layer thickness to the total thickness of the two surface layers in the diffusion plates of Examples 3 and 6 is 9:1, while the ratio in Example 5 is 6:4. Furthermore, Examples 3 and 6 show better light diffusion and MURA performance than Example 5. Therefore, it can be roughly inferred that the preferred implementation range of the ratio of the mainboard layer thickness to the total thickness of the two surface layers in the diffusion plate of the present invention should be between 9:1 and 7:3. Additionally, because Example 6 uses MS as the substrate for the two surface layers and PS as the substrate for the mainboard layer, Example 6 achieves better MURA performance than Example 3 (where both surface layers and the mainboard layer are made of PS).
[0091] Table 4: Comparison of the changes in the material and thickness ratio of the main body layer and the two surface layers of the diffuser plate
[0092]
[0093] In Table 5 below, Example 4-1 uses the same structure and material as Example 4, but with an additional optical film attached to the light-emitting surface of the diffuser plate. Comparative Example 3-1 uses the same structure and material as Example 3, but without any surface microstructures on the light-emitting surface of the diffuser plate. As shown in Table 5, the optical adhesive in Example 7 has a lower luminance because its thickness is greater than 20 μm. Furthermore, Comparative Example 3-1 also has lower luminance because its diffuser plate has no surface microstructures.
[0094] Table 5: Comparison of the thickness of optical film and optical adhesive adhered to the light-emitting surface of the diffuser plate
[0095] In Table 6 below, Example 4-2 uses the same structure and materials as Example 4, but with an additional reflective film attached to the light-incident surface of the diffuser plate. As can be seen from Table 6, because a reflective film is attached to the light-incident surface of the diffuser plate in Example 4-2, the diffuser plate in Example 4-2 can achieve better quality at low OD compared to Example 4.
[0096] Table 6: Comparison of reflective films attached to the incident surface of diffuser plates
[0097] As can be seen from Tables 1 to 6 above, the structures and materials of Embodiments 4-1, 4-2 and 6, which are made according to the technical concept of the present invention, are the best embodiments of the diffuser plate of the present invention applied to the low optical path distance backlight module, and can achieve relatively optimal optical performance.
[0098] In one embodiment, the diffuser plate of the present invention can be assembled onto a backlight module using a blue light-emitting diode (Blue LED) as the lower light source. A plurality of microstructures with a plurality of recesses and protrusions are formed on the upper surface of the diffuser plate. A quantum dot layer containing a plurality of green quantum dots and a plurality of red quantum dots is coated into the recesses of the plurality of microstructures. A water- and gas-barrier layer is then disposed on the upper surface of the quantum dot layer. By using the plurality of protrusions of the plurality of microstructures to separate the quantum dot layers located within the plurality of recesses, making each layer independent, external moisture and oxygen cannot penetrate the four side faces of the quantum dot layer and invade the entire quantum dot layer. This offers advantages such as simple manufacturing process, low cost, and high production yield. The present invention attaches a water-blocking and gas-blocking film to the upper surface of the diffuser plate, and uses microstructure to block water vapor from entering the quantum dot layer from the side end face, thereby minimizing the distance that water vapor has to travel from the end face to the quantum dot layer. Since it is extruded and integrally formed, it can reduce subsequent processing and production costs, and achieve a relatively high production yield.
[0099] Please refer to Figures 6 and 7, which are respectively a cross-sectional view and a three-dimensional exploded view of the fourth embodiment of the present invention, in which a diffuser plate is installed in a low optical path distance backlight module. In the fourth embodiment, the backlight module also includes, from bottom to top, a substrate 91, a plurality of light-emitting elements 92, and a diffuser plate. The diffuser plate is located above the substrate 91 and also includes: a plate body 10 (including a main plate layer 101, an upper surface layer 102, and a lower surface layer 103), a first diffuser particle additive (including first diffuser particles 1011), a second diffuser particle additive (including second diffuser particles 1021 and 1031), a plurality of microbubbles 1012, and a plurality of microstructures 11 and 1032. The diffusion plate of the fourth embodiment must also meet at least one of the following two conditions: Condition 1: The refractive index of the first material of the first diffusion particle 1011 is less than the refractive index of the second material of the second diffusion particles 1021 and 1031; Condition 2: The first weight percentage of the first diffusion particle additive is less than the second weight percentage of the second diffusion particle additive. Since most of the components, structures and functions of the diffusion plate of the fourth embodiment shown in Figures 6 and 7 are the same as or similar to those of the first embodiment shown in Figure 2, the details of these same or similar components will not be repeated. The difference from the first embodiment is that, in this fourth embodiment shown in Figures 6 and 7, the diffusion plate further includes: a quantum dot layer 12 and a water-blocking and gas-blocking layer 13; and the plurality of microstructures 11 disposed on the upper surface of the plate body 10 also have a special structure different from that of the previous embodiment.
[0100] In the fourth embodiment, the plate body 10 is a three-layer plate structure based on polystyrene (PS), and the thickness of the plate body 10 is preferably between 0.8 mm and 2.5 mm. The plate body 10 of the diffusion plate is located above the substrate 91 and adjacent to the substrate 91, and generally there are no other components between the plate body 10 of the diffusion plate and the light-emitting element 92 provided on the substrate 91. The quantum dot layer 12 requires a consistent blue light intensity to convert red / green light into uniform white light; since the ambient light intensity of the display is lower than the central intensity, there is likely to be insufficient red / green light conversion, resulting in a blue light phenomenon around the display. The plate body 10 of the present invention is formed by foaming extrusion, and includes a plurality of microbubbles 1012 and diffusion particles 1011, 1021, 1031 therein, having higher light refraction and light diffusion effects, improving the light intensity in the surrounding area of the display, and thus improving the blue light problem. A plurality of microstructures 11 are arranged in an array on the upper surface of the plate body 10, and a plurality of convex portions 111 and a plurality of concave portions 112 are formed on the upper surface of the plate body 10. The plurality of concave portions 112 are separated by the plurality of convex portions 111, so the plurality of concave portions 112 are independent of each other and do not communicate with each other. The quantum dot layer 12 is disposed at the plurality of concave portions 112 on the upper surface of the plate body 10, and the quantum dot layer 12 is not disposed at the plurality of convex portions 111. Among them, the thickness of the quantum dot layer 12 is t1, the distance from the top of one of the plurality of convex portions 111 to the bottom of one of the plurality of concave portions 112 is t2, and t1 < t2. In other words, the height t2 of the convex portion 111 of the microstructure 11 is greater than the thickness t1 of the quantum dot layer 12, so that the quantum dot layers 12 located in different concave portions 112 do not communicate with each other or contact each other. The water and oxygen barrier layer 13 is disposed on the entire upper surface of the plate body 10 and closely covers the plurality of convex portions 111 and the quantum dot layer 12. The water and oxygen barrier layer 13 can isolate and prevent external moisture and oxygen from invading the upper surface of the quantum dot layer 12. The thickness of the water and oxygen barrier layer 13 is t3, and it can be selected from commercially available water and oxygen barrier films and directly bonded to the convex portions 111 of the plurality of microstructures 11 and the quantum dot layer 12 on the upper surface of the plate body 10. The distance between two adjacent convex portions 111 is P. In the fourth embodiment, the quantum dot layer 12 includes a plurality of quantum dots 120 (Quantum Dot; abbreviated as QD). The plurality of quantum dots 120 can be selected from commercially available nanocrystal semiconductor materials composed of II-VI, III-V or IV-VI group elements, and the grain diameter of each quantum dot 120 is between 2 and 10 nm. Among them, the emission wavelength of the plurality of quantum dots 120 in the quantum dot layer 12 can be between 490 and 650 nm; in this embodiment, the plurality of quantum dots 120 include a plurality of green quantum dots with an emission wavelength of 520 to 530 nm and a plurality of red quantum dots with an emission wavelength of 620 to 630 nm.The blue light 211 emitted upward by the light-emitting element 92 can be mixed into white light 212 after passing through the quantum dot layer 12 and exits upward from the upper surface of the board body 10 and is emitted toward the liquid crystal panel 93.
[0101] In this embodiment, the feasible range of the thickness t1 of the quantum dot layer 12 is between 5 and 150 μm, but the preferable feasible range is that t1 is between 10 and 40 μm. The feasible range of the distance from the top of the plurality of convex portions 111 to the bottom of the plurality of concave portions 112 (or the height of the convex portion) t2 is between 6 and 200 μm, but the preferable feasible range is that t2 is between 25 and 50 μm; and, t1 < t2. The feasible range of the thickness t3 of the water and gas barrier layer 13 is between 5 and 100 μm, but the preferable feasible range is that t3 is between 10 and 30 μm. The maximum width of the convex portion 111 is between 50 and 500 μm. The feasible range of the distance P between two adjacent convex portions 111 is between 50 and 1000 μm, but the preferable feasible range is that P is between 250 and 500 μm.
[0102] Please refer to Figure 8, which is a cross-sectional schematic diagram of the fifth embodiment of the present invention applied to a low optical path distance backlight module, wherein the diffuser plate is installed in a backlight module. In the fifth embodiment, the backlight module also includes, from bottom to top, a substrate 91, a plurality of light-emitting elements 92, and a diffuser plate. The diffuser plate is located above the substrate 91 and also includes: a plate body 10 (including a main plate layer 101, an upper surface layer 102, and a lower surface layer 103), a first diffusion particle additive (including first diffusion particles 1011), a second diffusion particle additive (including second diffusion particles 1021 and 1031), a plurality of microbubbles 1012, a plurality of microstructures 11, a quantum dot layer 12, and a water-blocking and gas-blocking layer 13. The diffusion plate of the fifth embodiment must also meet at least one of the following two conditions: Condition 1: The refractive index of the first material of the first diffusion particle 1011 is less than the refractive index of the second material of the second diffusion particles 1021 and 1031; Condition 2: The first weight percentage of the first diffusion particle additive is less than the second weight percentage of the second diffusion particle additive. Since most of the components, structures and functions of the diffusion plate of the fifth embodiment shown in FIG8 are the same as or similar to those of the fourth embodiment shown in FIG6 and FIG7, the details of these same or similar components will not be repeated. The difference from the aforementioned fourth embodiment is that, in this fifth embodiment shown in FIG8, the diffusion plate of the present invention has a plurality of microstructures 11, quantum dot layers 12 and water-blocking and gas-blocking layers 13 respectively provided on the upper and lower surfaces of the plate body 10. In other words, the fifth embodiment shown in Figure 8, in addition to having the same plurality of microstructures 11, quantum dot layers 12, and water- and gas-barrier layers 13 on the upper surface of the plate 10 as the embodiments shown in Figures 6 and 7, also has a plurality of the same microstructures 11, quantum dot layers 12, and water- and gas-barrier layers 13 on the lower surface of the plate 10. The plurality of microstructures 11 form a plurality of protrusions 111 and a plurality of recesses 112 on the lower surface of the plate 10. The plurality of recesses 112 are separated by the plurality of protrusions 111, so the plurality of recesses 112 on the lower surface of the plate 10 are independent and not interconnected. Furthermore, the quantum dot layers 12 located on the lower surface of the plate 10 are disposed at the plurality of recesses 112 on the lower surface of the plate 10. Furthermore, the water- and gas-barrier layer 13 on the lower surface of the plate 10 is a plurality of protrusions 111 and a quantum dot layer 12 covering the lower surface of the plate 10. In this embodiment, the plurality of microstructures 11, quantum dot layers 12, and water- and gas-barrier layers 13 disposed on the upper and lower surfaces of the plate 10 have essentially the same structure, and the thickness of the quantum dot layer 12 is also less than the height of the protrusions 111 of the microstructure 11.
[0103] However, the embodiments described above should not be used to limit the scope of application of this invention. The scope of protection of this invention should be based on the technical spirit and equivalent variations defined in the claims of this invention. That is, all equivalent variations and modifications made in accordance with the claims of this invention will not lose the essence of this invention, nor will they depart from the spirit and scope of this invention. Therefore, they should all be regarded as further implementations of this invention.
[0104]
[0105] 10:Plate body
[0106] 101: Motherboard Layer
[0107] 1011, 1021, 1031: Diffused particles
[0108] 1012: Microbubbles
[0109] 102, 103: Surface layer
[0110] 11, 1022, 1032: Microstructure
[0111] 111:convex part
[0112] 112: concave part
[0113] 12: Quantum dot layer
[0114] 120:Quantum dots
[0115] 13: Water and gas barrier layer
[0116] 15: Optical film
[0117] 151: Optical adhesive
[0118] 152: Reflective film
[0119] 211: Blue Light
[0120] 212: White Light
[0121] 91:Substrate
[0122] 911: Top surface
[0123] 92: Light-emitting element
[0124] 93: LCD panel
Claims
1. A diffuser plate for use in a low optical path distance backlight module, which can be assembled onto a backlight module; The backlight module includes: a substrate and a plurality of light-emitting elements arranged on the substrate in an array form; the diffusion plate is located above the substrate and includes: a plate body having an upper surface and a lower surface, the lower surface facing the substrate; the plate body is a multi-layer structure formed by coextrusion, which including a main board layer, an upper surface layer, and a lower surface layer; the upper surface layer is laminated on the side of the main board layer facing the upper surface, and the lower surface layer is laminated on the side of the main board layer facing the lower surface; a first diffusion particle additive added to the main board layer; the first diffusion particle additive contains a plurality of first diffusion particles; the weight percentage of the added first diffusion particle additive in the main board layer is a first weight percentage; each of the first diffusion particles has a first material refractive index; and a second diffusion particle additive added to the upper surface layer and the lower surface layer; the second diffusion particle additive contains a plurality of second diffusion particles; the weight percentage of the added second diffusion particle additive in the upper surface layer and the lower surface layer is a second weight percentage; each of the second diffusion particles has a second material refractive index; wherein, the diffusion plate meets at least one of the following two conditions: Condition 1: the first material refractive index of the first diffusion particles is less than the second material refractive index of the second diffusion particles; and Condition 2: the first weight percentage of the first diffusion particle additive is less than the second weight percentage of the second diffusion particle additive; wherein, the diffusion plate further includes: a plurality of micro-structures arranged on at least the upper surface of the plate body in an array form; the plurality of micro-structures form a plurality of convex portions and a plurality of concave portions on the upper surface of the plate body, and the plurality of concave portions are separated by the plurality of convex portions, so the plurality of concave portions on the upper surface of the plate body are independent of each other and do not communicate with each other; a quantum dot layer disposed at the plurality of concave portions on the upper surface of the plate body; wherein, the thickness of the quantum dot layer is t1, and the distance from the top of the plurality of convex portions to the bottom of the plurality of concave portions is t2, and, t1 < t2; and a water and oxygen barrier layer disposed on the upper surface of the plate body and covering the plurality of convex portions and the quantum dot layer.
2. The diffuser plate as described in claim 1, used in a low optical path distance backlight module, wherein, A plurality of the micro-structures, the quantum dot layer, and the water and oxygen barrier layer are also disposed on the lower surface of the plate body; the plurality of micro-structures form a plurality of the convex portions and a plurality of the concave portions on the lower surface of the plate body, and the plurality of concave portions are separated by the plurality of convex portions, so the plurality of concave portions on the lower surface of the plate body are independent of each other and do not communicate with each other; and, the quantum dot layer located on the lower surface of the plate body is disposed at the plurality of concave portions on the lower surface of the plate body; in addition, the water and oxygen barrier layer on the lower surface of the plate body covers the plurality of convex portions and the quantum dot layer on the lower surface of the plate body.
3. The diffuser plate as described in claim 1, used in a low optical path distance backlight module, wherein, The quantum dot layer contains a plurality of quantum dots (QDs); the plurality of quantum dots are nanocrystal semiconductor materials composed of group II-VI, III-V or IV-VI elements, and the grain diameter of each quantum dot is between 2 and 10 nm; among them, the plurality of quantum dots include a plurality of green quantum dots with an emission wavelength of 520-530 nm and a plurality of red quantum dots with an emission wavelength of 620-630 nm.
4. The diffuser plate as described in claim 1, used in a low optical path distance backlight module, wherein, The plurality of microstructures comprises a plurality of N-sided pyramids, where N is a positive integer greater than or equal to three; t2 is between 25 and 50 μm, and t1 is between 10 and 40 μm; the thickness of the water- and gas-barrier layer is t3, which is between 10 and 30 μm; the maximum width of the protrusion is between 50 and 500 μm, and the distance between two adjacent protrusions is between 50 and 1000 μm.
5. The diffuser plate as described in claim 1, used in a low optical path distance backlight module, wherein, The diffuser plate further includes: an upper optical film attached to the upper surface of the plate body by means of an optical adhesive; wherein the thickness of the optical film is between 5 and 20 μm; a lower optical film attached to the lower surface of the plate body by means of an optical adhesive; and a reflective film attached below the lower optical film; wherein the reflective film has a reflectivity of <20% for light with wavelengths below 500 nm, and a reflectivity of >90% for light with wavelengths above 500 nm.