Quantum dot light diffusion plate and manufacturing method thereof

Abstract

The invention discloses a quantum dot light diffusion plate and a manufacturing method thereof. The diffusion plate can be assembled on a backlight module with a blue light emitting diode (LED) as a lower light source. A plurality of microstructures with a plurality of concave parts and convex parts are formed on the surface of a diffusion plate, a quantum dot layer containing a plurality of green quantum dots and a plurality of red quantum dots is coated in the plurality of concave parts of the plurality of microstructures, and then a water and gas blocking layer is arranged on the upper surface of the quantum dot layer. The quantum dot layer in the plurality of concave parts is separated by the plurality of convex parts of the plurality of microstructures to be independent from each other, so that external moisture and oxygen cannot penetrate through the four side end surfaces of the quantum dot layer to intrude into the whole quantum dot layer, and the quantum dot display device has the advantages of simple manufacturing process, low cost, high production qualification rate and the like.

Description

[0001] This application is a divisional application of the invention patent application with the application date of January 29, 2022, application number 202210112522.5, and invention name “Quantum dot light diffuser plate and its manufacturing method”. Technical Field

[0002] The present invention relates to a quantum dot light diffuser plate and a method for making the same, and more particularly to a quantum dot light diffuser plate that can be assembled in a backlight module and can prevent the quantum dot layer on the light diffuser plate from being degraded in activity due to the intrusion of moisture and oxygen. Background Art

[0003] In the broader landscape of backlit displays, traditional backlit displays utilize two main types of light-emitting diode (LED) light sources: one uses blue LEDs to excite yellow phosphors, mixing the two colors to create white light; the other uses three primary colors of LEDs to create white light. However, existing backlit displays using these two light sources suffer from a low color gamut and insufficient color reproduction.

[0004] Currently, the light source for backlight displays is a blue LED that excites green and red quantum dots. The three lights mix to form white light, which can increase the color gamut to 120% of NTSC. However, this type of backlight display still has the following disadvantages. First, quantum dots are easily affected by moisture and oxygen, which can reduce or even lose their activity. After long-term use, quantum dots fail, resulting in color anomalies in the display. Second, blue LEDs excite green and red quantum dots, and the blue, green, and red lights mix to form white light. This requires consistent light intensity to avoid insufficient red / green light conversion. However, because the intensity of the surrounding light is lower than the intensity of the central light, the display has a blue light phenomenon around it, resulting in inconsistent colors. Furthermore, most existing quantum dot films use a surface-attached water and gas barrier film to block moisture and oxygen. However, this method can only block moisture and oxygen from entering the quantum dot film from the top surface, and cannot prevent moisture and oxygen from entering from the side end faces of the quantum dot film. Therefore, after a period of use, the four sides of the backlight display's quantum dot film will still be invaded by moisture and oxygen, causing the quantum dots to fail and resulting in color abnormalities around the edges of the backlight display. Although some industry insiders have tried applying a protective coating to the four side edges of the backlight display's quantum dot film, this method requires multiple processing steps, is complex, costly, and has a low yield rate.

[0005] Therefore, the present invention provides a quantum dot light diffuser plate and its manufacturing method, which can be assembled in a backlight module and can prevent the quantum dot layer on the light diffuser plate from being degraded due to the invasion of moisture and oxygen, thereby solving the various deficiencies of the aforementioned conventional backlight displays. Summary of the Invention

[0006] The main object of the present invention is to provide a diffusion plate, which can be assembled on a backlight module using blue light-emitting diodes (LEDs) as a light source. A plurality of microstructures having a plurality of recesses and protrusions are formed on the surface of the diffusion plate, and a quantum dot layer including a plurality of green quantum dots and a plurality of red quantum dots is coated in the plurality of recesses of the plurality of microstructures. Then, a water and oxygen barrier layer is provided on the upper surface of the quantum dot layer. The plurality of protrusions of the plurality of microstructures are used to separate the quantum dot layers located in the plurality of recesses so that they are independent of each other, thereby preventing water vapor and oxygen from the outside from invading the entire quantum dot layer through the four side edges of the quantum dot layer. It has the advantages of simple process, low cost and high production qualification rate.

[0007] To achieve the above object, the present invention provides a quantum dot light diffusion plate, which can be combined with a backlight module. The backlight module includes: a substrate and a plurality of blue light-emitting elements arranged in an array on the substrate. The diffusion plate is located above the substrate and includes: a plate body, a plurality of microstructures, a quantum dot layer and a water and oxygen barrier layer. The plate body has an upper surface and a lower surface, and the lower surface faces the substrate. A plurality of microstructures are arranged in an array on the upper surface of the plate body; the plurality of microstructures form a plurality of protrusions and a plurality of recesses on the upper surface of the plate body, and the plurality of recesses are separated by the plurality of protrusions, so the plurality of recesses are independent of each other and do not communicate with each other. The quantum dot layer is provided at the plurality of recesses 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 protrusions to the bottom of the plurality of recesses is t2, and t1 < t2. The water and oxygen barrier layer is provided on the upper surface of the plate body and covers the plurality of protrusions and the quantum dot layer.

[0008] In an embodiment, a plurality of the microstructures, the quantum dot layer and the water and oxygen barrier layer are also provided on the lower surface of the plate body; the plurality of microstructures form a plurality of protrusions and a plurality of recesses on the lower surface of the plate body, and the plurality of recesses are separated by the plurality of protrusions, so the plurality of recesses 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 provided at the plurality of recesses 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 protrusions and the quantum dot layer on the lower surface of the plate body.

[0009] In one embodiment, the quantum dot layer includes a plurality of quantum dots (QDs); the plurality of quantum dots are a 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 having a light emission wavelength of 520 to 530 nm and a plurality of red quantum dots having a light emission wavelength of 620 to 630 nm.

[0010] In one embodiment, the plurality of microstructures include a plurality of N-sided pyramids, wherein 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.

[0011] 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.

[0012] In one embodiment, the maximum width of the protrusion is between 50 μm and 500 μm, and the distance between two adjacent protrusions is between 50 μm and 1000 μm.

[0013] 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).

[0014] In one embodiment, the plate is formed by foam extrusion, and contains a plurality of microbubbles in the plate; the microbubbles reduce the weight of the plate by 15-25%, and the average size of the microbubbles is between 60-800 μm;

[0015] The calculation formula for the weight loss rate is:

[0016] Weight loss rate (%) = (W1-W2) / W2*100%;

[0017] W1=H*(L1*L2*D);

[0018] in:

[0019] H is the average thickness of the plate (mm);

[0020] L1 is the length of the plate (mm);

[0021] L2 is the width of the plate (mm);

[0022] D is the specific gravity of the raw material of the plate (g / mm 3 );

[0023] W1 is the theoretical weight (g) of the plate body, that is, the weight without the plurality of microbubbles;

[0024] W2 is the actual weight (g) of the plate body, that is, the actual weight of the plate body containing the plurality of microbubbles actually measured by a weighing scale.

[0025] In one embodiment, the plurality of microbubbles are generated by adding a foaming agent and a nucleating agent in the foam extrusion molding process of the plate body; the nucleating agent includes at least one of the following: calcium carbonate, silicon dioxide, calcium oxide; the weight percentage of the added nucleating agent is 0.1%-0.5%.

[0026] In one embodiment, the plate body is a multi-layer structure formed by co-extrusion of at least two different materials.

[0027] To achieve the above object, the present invention provides a method for manufacturing a quantum dot diffusion plate, which includes the following steps: First, a plate body is manufactured through a foam extrusion molding process. The plate body has an upper surface and a lower surface, and a plurality of micro-structures are extruded on at least the upper surface of the plate body. The plurality of micro-structures are arranged in an array form on the upper surface of the plate body and form a plurality of convex portions and a plurality of concave portions on the upper surface of the plate body. 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. Then, a quantum dot layer is coated at the plurality of concave portions on the upper surface of the plate body through a coating process. Wherein, the thickness of the quantum dot layer is t1, 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. After that, through a pasting process, a water and gas barrier layer is pasted on the upper surface of the plate body and covers the plurality of convex portions and the quantum dot layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic cross-sectional view of an embodiment of the quantum dot light diffusion plate of the present invention installed on a backlight module.

[0029] Figure 2 It is a schematic three-dimensional exploded view of an embodiment of the quantum dot light diffusion plate of the present invention installed on a backlight module.

[0030] Figures 3A to 3E They are respectively schematic views of several different embodiments of the micro-structure of the quantum dot light diffusion plate of the present invention.

[0031] Figure 4 It is a schematic cross-sectional view of another embodiment of the quantum dot light diffusion plate of the present invention installed on a backlight module.

[0032] Explanation of the accompanying drawings: 20-substrate; 21-light-emitting element; 211-blue light; 212-white light; 10-board; 101-main board layer; 102-upper surface layer; 103-lower surface layer; 11-microstructure; 111-convex portion; 112-concave portion; 12-quantum dot layer; 120-quantum dot; 13-water- and gas-blocking layer; 100-microbubbles. DETAILED DESCRIPTION

[0033] The present invention relates to a quantum dot light diffuser plate and a method for manufacturing the same. The diffuser plate can be assembled on a backlight module with a blue light emitting diode (LED) as the lower light source. A plurality of microstructures having a plurality of concave and convex portions are formed on the surface of the diffuser plate, and a quantum dot layer comprising a plurality of green quantum dots and a plurality of red quantum dots is coated in the plurality of concave portions of the plurality of microstructures. A water and gas barrier layer is then provided on the upper surface of the quantum dot layer. The plurality of convex portions of the plurality of microstructures are used to separate the quantum dot layers located in the plurality of concave portions so that they are independent of each other, thereby preventing external water vapor and oxygen from penetrating the entire quantum dot layer through the four side end faces of the quantum dot layer. The process is simple, the cost is low, and the production yield is high. The present invention adheres a water- and gas-blocking film to the upper surface of the diffuser plate, and uses a microstructure to block water vapor from entering the quantum dot layer from the side end face, thereby minimizing the distance that water vapor enters the quantum dot layer from the end face. Moreover, since the device is formed by extrusion in one piece, subsequent processing steps and production costs can be reduced, and a relatively high production yield can be achieved.

[0034] In order to more clearly describe the quantum dot light diffuser plate and its manufacturing method proposed in the present invention, they are described in detail below with reference to the drawings.

[0035] See also Figure 1 and Figure 2 The figures show a cross-sectional schematic diagram and a perspective exploded view of an embodiment of a quantum dot light diffuser plate according to the present invention, mounted on a backlight module. In this embodiment, the backlight module comprises, from bottom to top, a substrate 20, a plurality of light-emitting elements 21, and a diffuser plate. The diffuser plate comprises a plate body 10, a plurality of microstructures 11, a quantum dot layer 12, and a water and gas barrier layer 13.

[0036] A circuit layout is provided on the substrate 20. A plurality of light-emitting elements 21 are arranged in an array on the substrate 20 and electrically coupled to the circuit layout. In the present invention, the plurality of light-emitting elements 21 are blue light-emitting diodes (LEDs) that emit blue light 211 upward toward the diffuser plate 10. In this embodiment, the plurality of light-emitting elements 21 can be traditional blue LEDs, blue Mini LEDs, or even blue Micro LEDs. A reflective layer (not numbered) is provided on the top surface of the substrate 20. This reflective layer can be white or another color or surface with a better light-reflecting effect to reflect light upward toward the diffuser plate 10. The base material of the diffuser plate 10 can be an amorphous or semi-crystalline plastic material, including at least one of the following: polycarbonate (PC), polystyrene (PS), polymethyl methacrylate (PMMA, commonly known as acrylic), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or copolymers of any of the foregoing materials. In this embodiment, the plate 10 is a single-layer structure based on polystyrene (PS), preferably with a thickness between 0.8 mm and 2.5 mm. The diffuser plate 10 is positioned above and adjacent to the substrate 20. Generally, no other components are located between the diffuser plate 10 and the light-emitting elements 21 disposed on the substrate 20. The quantum dot layer 12 requires consistent blue light intensity to convert red and green light, mixing them into uniform white light. Because the peripheral light intensity of a display is lower than the central light intensity, insufficient red and green light conversion can occur, resulting in a bluish cast around the display. The plate 10 of the present invention is formed by foam extrusion. The plate 10 contains a plurality of microbubbles 100, resulting in a higher light refraction effect, increasing the light intensity in the area surrounding the display and thereby alleviating the bluish cast problem. In one embodiment, diffuser particles, which can be commercially available, may be added to the diffuser plate 10 to further enhance the light diffusion effect of the diffuser plate.

[0037] In this embodiment, the weight reduction rate of the plurality of microbubbles 100 relative to the plate 10 can be implemented in a range of 10-35%, with a weight reduction rate of 15-25% being a preferred implementation range. Furthermore, the average size of the plurality of microbubbles 100 is in a range of 60-800 μm. The weight reduction rate is calculated as follows:

[0038] Weight loss rate (%) = (W1-W2) / W2*100%;

[0039] W1=H*(L1*L2*D);

[0040] in:

[0041] H is the average thickness of the plate (mm);

[0042] L1 is the length of the plate (mm);

[0043] L2 is the width of the plate (mm);

[0044] D is the specific gravity of the raw material of the plate (g / mm 3 );

[0045] W1 is the theoretical weight of the plate (g), i.e., the weight without the microbubbles;

[0046] W2 is the actual weight of the plate (g), that is, the actual weight of the plate containing the plurality of microbubbles measured by a scale.

[0047] In this embodiment, the plurality of microbubbles 100 are generated by adding a foaming agent and a nucleating agent during the foam extrusion molding process of the sheet 10. The nucleating agent comprises at least one of the following: calcium carbonate, silicon dioxide, or calcium oxide. The weight percentage of the added nucleating agent can range from 0.01% to 5%, with a preferred range of 0.1% to 0.5%. The weight loss rate of the microbubbles 100 can be controlled by adjusting the amount of foaming agent added, and the bubble diameter of the microbubbles 100 can be controlled by adding the nucleating agent and adjusting the process temperature.

[0048] In this embodiment, the diffusion plate includes: a plate body 10, a plurality of microstructures 11 (Micro-Structures), a quantum dot layer 12, and a water and oxygen barrier layer 13. The plate body 10 has an upper surface and a lower surface, and the lower surface faces the substrate 20. The plurality of microstructures 11 are arranged on the upper surface of the plate body 10 in an array form, 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. Wherein, the thickness of the quantum dot layer 12 is t1, and 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 and do not contact the water and oxygen barrier layer 13. 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. Through the water and oxygen barrier layer 13, external moisture and oxygen can be isolated and prevented 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 adhered 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 this embodiment,

[0049] The quantum dot layer 12 contains a plurality of quantum dots 120 (Quantum Dot; abbreviated as QD). The plurality of quantum dots 120 can be selected from commercially available nanocrystalline semiconductor materials and are composed of elements of II-VI, III-V or IV-VI groups. 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 21 can be mixed into white light 212 and emitted upward from the upper surface of the plate body 10 after passing through the quantum dot layer 12.

[0050] In this embodiment, the feasible range of the thickness t1 of the quantum dot layer 12 is between 5 and 150 μm, but the preferred feasible range is that t1 is between 10 and 40 μm. The feasible range of the distance from the tops of the plurality of convex portions 111 to the bottoms of the plurality of concave portions 112 (or the height of the convex portions, which can be called) t2 is between 6 and 200 μm, but the preferred 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 preferred 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 preferred feasible range is that P is between 250 and 500 μm.

[0051] Please refer to Figures 3A to 3E , which are schematic diagrams of several different embodiments of the microstructure of the quantum dot light diffusing plate of the present invention. In the present invention, the plurality of microstructures include a plurality of N-sided pyramids, where N is a positive integer greater than or equal to three; and the plurality of microstructures can be composed of pyramids of a single shape or a combination of pyramids of two or more different shapes. Pyramids are called differently according to the shape of the base surface, depending on the polygon of the base surface; for example, a pyramid with a triangular base surface is called a triangular pyramid, and a pyramid with a square base surface is called a square pyramid, and so on. A pyramid with an N-sided base has a total of N + 1 vertices, N + 1 faces, and 2N edges. The dual polyhedron of a pyramid is a pyramid of the same shape, for example, the dual polyhedron of a square pyramid is an inverted square pyramid. As Figure 3A shown in the embodiment, each microstructure presents a triangular pyramid (N = 3) in the top view. As Figure 3B shown, the plurality of microstructures include a combination of two different pyramids, namely a hexagonal pyramid (N = 6) and a triangular pyramid (N = 3) presented in the top view. As Figure 3C shown, each microstructure presents a quadrilateral pyramid (N = 4), that is, a square pyramid or a pyramid-shaped pyramid, in the top view. As Figure 3D shown, the plurality of microstructures include a combination of two different pyramids, namely a quadrilateral pyramid (N = 4) and a triangular pyramid (N = 3) presented in the top view. As Figure 3E shown, each microstructure presents a quadrilateral pyramid (N = 4), that is, a square pyramid or a pyramid-shaped pyramid shape, but the width of the convex portion of each microstructure in the Y-axis direction is greater than the width of the convex portion in the X-axis direction.

[0052] The present invention sets up several pyramid-shaped microstructures of different depths on the upper surface of the diffuser plate body to match the quantum dot (QD) layer of the same thickness for testing, in order to compare the degree of edge failure achieved by microstructures with different depths after environmental testing. Table 1 below shows the structural information of each comparative example tested. For example, the upper surface of the diffuser plate of Comparative Example 1 is "flat", so the depth and spacing values of its surface microstructure are both "NA", that is, 0. In other words, the quantum dot (QD) layer is attached to the upper surface of the diffuser plate in the form of a whole flat QD film, and the thickness of the QD film is 20μm. After the comparative example 1 was tested in the 60℃ 90% RH-1000hr environment, it was found that the quantum dot layer had a failure degree of 1cm width around the edges of the diffuser plate. The diffuser plate in Comparative Example 2 has a matte top surface and a microstructure depth of Ra15. In other words, the quantum dot (QD) layer is applied entirely to the diffuser plate's top surface, and the QD layer is 20 μm thick. After environmental testing at 60°C, 90% RH, and 1000 hours, the quantum dot layer in Comparative Example 2 exhibited failures up to 1 cm along the edges of the diffuser plate. In Comparative Example 3, the microstructures on the diffuser plate's top surface were only 5 μm deep, while the quantum dot (QD) layer was 20 μm thick. In other words, the quantum dot (QD) layer was thicker than the depth of the microstructures. After environmental testing at 60°C, 90% RH, and 1000 hours, the quantum dot layer in Comparative Example 3 exhibited failures up to 1 cm along the edges of the diffuser plate. In Example 1 of the present invention, the microstructures on the top surface of the diffuser plate are 30 μm deep, while the quantum dot (QD) layer is 20 μm thick. In other words, the QD layer thickness is smaller than the depth of the microstructures. After testing Example 1 at 60°C, 90% RH for 1000 hours, the quantum dot layer failure rate around the diffuser plate was only 0.2 cm wide. This indicates that when the QD layer thickness is smaller than the depth of the microstructures (as in Example 1), the degree of quantum dot layer edge failure can be significantly reduced. The diffuser plate of Example 2 according to the present invention has microstructures and QD layers on both the upper and lower surfaces. The depth of the microstructures on both surfaces is 30 μm, while the thickness of the quantum dot (QD) layers on both surfaces is 15 μm. In other words, the thickness of each quantum dot (QD) layer is not only less than the depth of the microstructures, but also thinner than the thickness of the quantum dot layer of Example 1. After testing in a 60°C, 90% RH, 1000hr environment, it was found that the quantum dot layer failure at the edges of the diffuser plate was only 0.15 cm wide (due to the reduced thickness of each quantum dot layer), and the luminance was increased to 380 cd / m 2 (Because both the upper and lower surfaces of the diffuser plate are provided with microstructures and quantum dot layers), its performance is better than that of Example 1. Therefore, when both the upper and lower surfaces of the diffuser plate are provided with microstructures and quantum dot layers (such as Example 2), even better results can be achieved.

[0053] Table 1: Comparison of edge failure levels caused by microstructures of varying depths on the diffuser surface after environmental testing

[0054]

[0055] The present invention enhances light diffusion and reduces the distance of blue light around the backlight module by adding diffusing particles and a foaming agent to the diffuser plate. The applicant provided multiple diffusers with different weight ratios of foaming agent added to achieve different microbubble weight reduction ratios (as shown in Examples 3-4 and Comparative Examples 4-8 in Table 2). The authors measured the distance of blue light around the diffuser plate and the luminance value after each diffuser plate was assembled into the backlight module. The authors compared the weight reduction ratio (%) of the microbubbles contained in the diffuser plate with the distance of blue light around the backlight module and the luminance value. Table 2 below shows the structural information of the various diffuser plate examples tested and compared. As can be seen from Table 2, different foaming agent addition ratios result in different microbubble ratios within the diffuser plate, which affects the luminous uniformity (MURA) performance of the backlight module equipped with the diffuser plate. The higher the foaming agent addition ratio, the better the MURA shielding effect will be, but it will cause too much brightness loss (<3%). Among them, the weight reduction ratio is preferably 15-25%, such as Comparative Examples 5-6 and Example 4, which can achieve the relatively best comprehensive performance in brightness and MURA shielding effect.

[0056] Table 2: Comparison of the weight reduction ratio of diffuser plates containing different microbubbles relative to luminance value and distance from surrounding blue light

[0057]

[0058] In an embodiment of the present invention, the method for manufacturing the quantum dot light diffusing plate includes the following steps: First, a plate body is manufactured through a foaming extrusion molding process. The plate body has an upper surface and a lower surface, and a plurality of micro-structures are extruded on at least the upper surface of the plate body. The plurality of micro-structures are arranged in an array form on the upper surface of the plate body and form a plurality of convex portions and a plurality of concave portions on the upper surface of the plate body. 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. Then, a quantum dot layer is coated at the plurality of concave portions on the upper surface of the plate body through a coating process. Wherein, the thickness of the quantum dot layer is t1, 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. After that, through an adhesion process, a water and gas barrier layer is covered on the upper surface of the plate body and covers the plurality of convex portions and the quantum dot layer. The present invention prevents water vapor from invading the quantum dot layer from the upper surface by attaching a water and gas barrier film on the upper surface of the diffusing plate, and blocks water vapor from entering the quantum dot layer from the side end faces through the convex portions of the micro-structures, minimizing the distance for water vapor to enter the quantum dot layer from the end faces. And, since the diffusing plate is integrally formed by extrusion, subsequent processing processes and production costs can be reduced, and a relatively high production qualification rate can be achieved.

[0059] Please refer to Figure 4 , which is a schematic cross-sectional view of another embodiment of the quantum dot light diffusing plate of the present invention installed on a backlight module. Since Figure 4 the structures and functions of most components in the illustrated embodiment are the same as those in Figure 1 the illustrated embodiment, the same or similar components will be directly given the same component names and numbers, and their details will not be described in detail. In the Figure 4 illustrated embodiment, the plate body 10 is a multi-layer structure formed by co-extrusion of different materials including at least two layers (main board layer 101, upper surface layer 102, lower surface layer 103), and a plurality of micro-structures 11, quantum dot layers 12, and water and gas barrier layers 13 are respectively provided on the upper and lower surfaces of the plate body 10. In other words, Figure 4 in the illustrated embodiment, in addition to setting on the upper surface of the plate body 10 the same as Figure 1In addition to the multiple microstructures 11, quantum dot layer 12, and water- and gas-blocking layer 13 identical to those in the illustrated embodiment, the lower surface of the plate 10 is also provided with multiple microstructures 11, quantum dot layer 12, and water- and gas-blocking layer 13. The multiple microstructures 11 form multiple protrusions 111 and multiple recesses 112 on the lower surface of the plate 10. The multiple recesses 112 are separated by the multiple protrusions 111, so that the multiple recesses 112 on the lower surface of the plate 10 are independent and do not communicate with each other. Furthermore, the quantum dot layer 12 on the lower surface of the plate 10 is disposed within the multiple recesses 112 on the lower surface of the plate 10. Furthermore, the water- and gas-blocking layer 13 on the lower surface of the plate 10 covers the plurality of protrusions 111 and the quantum dot layer 12 on the lower surface of the plate 10. In this embodiment, the structures of the plurality of microstructures 11, the quantum dot layer 12, and the water- and gas-blocking layer 13 disposed on both the upper and lower surfaces of the plate 10 are substantially identical, and the thickness of the quantum dot layer 12 is also less than the height of the protrusions 111 of the microstructures 11.

[0060] The embodiments described above should not be used to limit the scope of application of the present invention. The scope of protection of the present invention should be based primarily on the technical spirit defined in the claims and their equivalents. In other words, any equivalent variations and modifications made in accordance with the claims will not diminish the essence of the present invention and will not depart from the spirit and scope of the present invention. Therefore, they should be considered further implementations of the present invention.

Claims

1. A quantum dot light diffuser plate for assembly into a backlight module; the backlight module comprises: A substrate and a plurality of blue light emitting elements are arranged on the substrate in an array; the diffuser is located above the substrate and includes: a plate having an upper surface and a lower surface, wherein the lower surface faces the substrate; A plurality of microstructures are arranged in an array on the upper surface of the plate; the plurality of microstructures form a plurality of convex portions and a plurality of concave portions on the upper surface of the plate; a quantum dot layer disposed on the plurality of microstructures on the upper surface of the plate; and a water and gas barrier layer, disposed on the upper surface of the plate and covering the quantum dot layer; The plate is formed by foam extrusion, and contains a plurality of microbubbles in the plate; the microbubbles reduce the weight of the plate by 15-25%, and the average size of the microbubbles is between 60-800 μm; The calculation formula for the weight loss rate is: Weight loss rate (%) = (W1-W2) / W2*100%; W1=H*(L1*L2*D); in: H is the average thickness of the plate; L1 is the length of the plate; L2 is the width of the plate; D is the specific gravity of the raw material of the plate; W1 is the theoretical weight of the plate, that is, the weight without the microbubbles; W2 is the actual weight of the plate, that is, the actual weight of the plate containing the plurality of microbubbles measured by a scale.

2. The quantum dot light diffuser plate according to claim 1, wherein: The plurality of microstructures include a plurality of N-sided pyramids, where N is a positive integer greater than or equal to three; the plurality of concave portions of the plurality of microstructures are separated by the plurality of convex portions, so that the plurality of concave portions are independent and not interconnected; The quantum dot layer is disposed on the plurality of recesses of the plurality of microstructures on the upper surface of the plate; wherein the thickness of the quantum dot layer is t1, the distance between a top of the plurality of protrusions and a bottom of the plurality of recesses is t2; t2 is between 25 and 50 μm, t1 is between 10 and 40 μm, and t1 <t2; The water- and gas-blocking layer covers the plurality of protrusions and the quantum dot layer, and the thickness of the water- and gas-blocking layer is t3, and t3 is between 10 and 30 μm; The maximum width of the convex portion is between 50 and 500 μm, and the distance between two adjacent convex portions is between 50 and 1000 μm.

3. The quantum dot light diffuser plate according to claim 2, wherein: A plurality of the microstructures, the quantum dot layer and the water- and gas-blocking layer are also provided on the lower surface of the plate body; the 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 the concave portions are separated by the plurality of the convex portions, so the plurality of the concave portions on the lower surface of the plate body are independent of each other and not connected to each other; and the quantum dot layer located on the lower surface of the plate body is provided at the plurality of the concave portions on the lower surface of the plate body; in addition, the water- and gas-blocking layer on the lower surface of the plate body covers the plurality of the convex portions and the quantum dot layer on the lower surface of the plate body.

4. The quantum dot light diffuser plate according to claim 1, wherein: The quantum dot layer includes a plurality of quantum dots; the plurality of quantum dots are a nanocrystalline 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 a light emission wavelength of 520 to 530 nm and a plurality of red quantum dots with a light emission wavelength of 620 to 630 nm; the plate body is a multilayer structure composed of at least two layers of different materials through co-extrusion; the material of the plate body includes one of the following: polycarbonate, polystyrene, polymethyl methacrylate, polyethylene, polypropylene, polyethylene terephthalate.

5. The quantum dot light diffuser plate according to claim 1, wherein: The plurality of microbubbles are generated by adding a foaming agent and a nucleating agent during the foam extrusion molding process of the plate; the nucleating agent comprises at least one of the following: calcium carbonate, silicon dioxide, and calcium oxide; and the weight percentage of the added nucleating agent is 0.1%-0.5%.

6. A method for preparing a quantum dot light diffuser plate, characterized in that: include: A plate is manufactured by a foam extrusion molding process, the plate having an upper surface and a lower surface, the plate containing a plurality of microbubbles; and a plurality of microstructures are extruded on at least the upper surface of the plate; the plurality of microstructures are arranged in an array on the upper surface of the plate to form a plurality of protrusions and a plurality of recesses on the upper surface of the plate; coating a quantum dot layer on the plurality of microstructures on the upper surface of the plate through a coating process; and Through a pasting process, a water- and gas-blocking layer is pasted on the upper surface of the plate and covers the quantum dot layer. The weight reduction rate of the plate body caused by the plurality of microbubbles is between 15% and 25%, and the average size of the plurality of microbubbles is between 60 and 800 μm. The calculation formula for the weight loss rate is: Weight loss rate (%) = (W1-W2) / W2*100%; W1=H*(L1*L2*D); in: H is the average thickness of the plate; L1 is the length of the plate; L2 is the width of the plate; D is the specific gravity of the raw material of the plate; W1 is the theoretical weight of the plate, that is, the weight without the microbubbles; W2 is the actual weight of the plate, that is, the actual weight of the plate containing the plurality of microbubbles measured by a scale.

7. The method for manufacturing a quantum dot light diffuser plate according to claim 6, wherein: The plurality of microstructures include a plurality of N-sided pyramids, where N is a positive integer greater than or equal to three; the plurality of concave portions of the plurality of microstructures are separated by the plurality of convex portions, so that the plurality of concave portions are independent and not interconnected; The quantum dot layer is coated on the plurality of recessed portions of the plurality of microstructures on the upper surface of the plate; wherein the thickness of the quantum dot layer is t1, the distance between a top of the plurality of protrusions and a bottom of the plurality of recessed portions is t2; t2 is between 25 and 50 μm, t1 is between 10 and 40 μm, and t1 <t2; The water- and gas-blocking layer covers the plurality of protrusions and the quantum dot layer, and the thickness of the water- and gas-blocking layer is t3, and t3 is between 10 and 30 μm; The maximum width of the convex portion is between 50 and 500 μm, and the distance between two adjacent convex portions is between 50 and 1000 μm.

8. The method for manufacturing a quantum dot light diffuser plate according to claim 7, wherein: A plurality of the microstructures, the quantum dot layer and the water- and gas-blocking layer are also provided on the lower surface of the plate body; the 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 the concave portions are separated by the plurality of the convex portions, so the plurality of the concave portions on the lower surface of the plate body are independent of each other and not connected to each other; and the quantum dot layer located on the lower surface of the plate body is provided at the plurality of the concave portions on the lower surface of the plate body; in addition, the water- and gas-blocking layer on the lower surface of the plate body covers the plurality of the convex portions and the quantum dot layer on the lower surface of the plate body.

9. The method for manufacturing a quantum dot light diffuser plate according to claim 6, wherein: The quantum dot layer includes a plurality of quantum dots; the plurality of quantum dots are a nanocrystalline 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 a light emission wavelength of 520 to 530 nm and a plurality of red quantum dots with a light emission wavelength of 620 to 630 nm; the plate body is a multilayer structure composed of at least two layers of different materials; the material of the plate body includes one of the following: polycarbonate, polystyrene, polymethyl methacrylate, polyethylene, polypropylene, polyethylene terephthalate.

10. The method for manufacturing a quantum dot light diffuser plate according to claim 6, wherein: The plurality of microbubbles are generated by adding a foaming agent and a nucleating agent during the foam extrusion molding process of the plate; the nucleating agent comprises at least one of the following: calcium carbonate, silicon dioxide, and calcium oxide; and the weight percentage of the added nucleating agent is 0.1%-0.5%.

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