Backlight module, manufacturing method thereof, and liquid crystal display device

Abstract

Embodiments of the present disclosure provide a backlight module, a manufacturing method thereof, and a liquid crystal display device. The backlight module includes a substrate, a plurality of light-emitting chips arranged in an array on a first surface of the substrate and emitting first-color light, a plurality of light conversion units connected to the substrate and corresponding to the plurality of light-emitting chips one by one, and a first reflection layer located between the plurality of light conversion units. The light conversion unit is located on a side of the light-emitting chip facing the substrate, and includes a scattering layer, a second reflection layer, and a light conversion layer arranged in sequence along a direction from the substrate to the light-emitting chip. The light conversion layer converts part of the first-color light into second-color and third-color light. The second reflection layer reflects part of the first-color light back to the light conversion layer, and transmits the second color, the third color, and part of the first-color light to form white light. The first reflection layer reflects the white light emitted from the scattering layer to a second surface of the substrate opposite to the first surface. Embodiments of the present disclosure can improve the color deviation problem of the white light emitted by the backlight module.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of display technologies, and particularly to a backlight module, a manufacturing method thereof, and a liquid crystal display device. Background Art

[0002] Liquid crystal display devices have the advantages of small volume, light weight, low radiation, etc., and are widely used in various fields. A liquid crystal display device includes a backlight module and a liquid crystal display panel. Among them, a Mini LED backlight module has the advantages of ultra-high resolution, high brightness, low power consumption, no splicing gap, and fast response.

[0003] In related technologies, the backlight module includes a substrate, a reflective layer, a plurality of light-emitting chips, a phosphor layer, and a scattering layer. The reflective layer is located on one side of the substrate, the plurality of light-emitting chips are arranged in an array on the side of the reflective layer away from the substrate, and the phosphor layer and the scattering layer are sequentially located on the side of the plurality of light-emitting chips away from the substrate. The light of a first color emitted by the plurality of light-emitting chips is emitted after passing through the phosphor layer and the scattering layer. Among them, the phosphor layer converts part of the light of the first color into light of other colors. The light of the first color that is not converted and the light of other colors are mixed to form white light.

[0004] Since the time for the light of the first color emitted by the light-emitting chips to pass through the phosphor layer is short, and the light of other colors obtained by conversion is less, the white light emitted by the backlight module is prone to color deviation. Summary of the Invention

[0005] The present disclosure provides a backlight module, a manufacturing method thereof, and a liquid crystal display device, which can improve the color deviation problem of the white light emitted by the backlight module.

[0006] On the one hand, a backlight module is provided. The backlight module includes a substrate, a plurality of light-emitting chips, a plurality of light conversion units, and a first reflective layer. The plurality of light-emitting chips are arranged in an array on a first surface of the substrate, and the plurality of light-emitting chips emit light of a first color. The plurality of light conversion units are connected to the substrate, and the plurality of light conversion units correspond to the plurality of light-emitting chips one by one. The light conversion unit is located on a side of a corresponding one of the light-emitting chips facing the substrate. The light conversion unit includes a scattering layer, a second reflective layer, and a light conversion layer arranged in sequence along a direction from the substrate to the light-emitting chip. The light conversion layer is configured to convert part of the light of the first color into light of a second color and light of a third color. The second reflective layer is configured to reflect a part of the light of the first color back to the light conversion layer, and transmit a part of the light of the first color, the light of the second color, and the light of the third color to form white light. The first reflective layer is located between adjacent ones of the plurality of light conversion units, and is configured to reflect the white light emitted from the scattering layer to a second surface of the substrate. The first surface and the second surface are opposite to each other.

[0007] Optionally, the second reflective layer includes a plurality of first dielectric layers and a plurality of second dielectric layers stacked alternately, and the refractive index of the first dielectric layer is different from that of the second dielectric layer.

[0008] Optionally, the second reflective layer includes the first structural layer and a plurality of second structural layers stacked on the first structural layer. The first structural layer includes two stacked first dielectric layers, and the second structural layer includes one stacked second dielectric layer and two stacked first dielectric layers. The thickness of the first dielectric layer is 50 nm to 70 nm, and the thickness of the second dielectric layer is 93 nm to 113 nm.

[0009] Optionally, the second reflective layer includes a plurality of stacked periodic structures. The periodic structure includes one stacked first dielectric layer and one stacked second dielectric layer. The thickness of the first dielectric layer is 35 nm to 55 nm, and the thickness of the second dielectric layer is 67 nm to 87 nm.

[0010] Optionally, the first dielectric layer is made of titanium dioxide, and the second dielectric layer is made of silicon dioxide.

[0011] Optionally, the second reflective layer has at least one opening.

[0012] Optionally, the ratio of the total area of the orthographic projection of the at least one opening on the first surface to the area enclosed by the outer contour of the orthographic projection of the second reflective layer on the first surface is 30% to 35%.

[0013] Optionally, the shape of the opening is circular, oval, square or rectangular.

[0014] Optionally, the substrate further includes a plurality of convex structures located on the first surface and between adjacent ones of the plurality of light conversion units, and the first reflective layer is in contact with the convex structures.

[0015] Optionally, the first reflective layer includes a first protective layer, a metal layer, and a second protective layer stacked in sequence.

[0016] Optionally, the substrate has a plurality of grooves, the plurality of grooves are arranged in an array on the first surface, and the plurality of light conversion units are located in the plurality of grooves.

[0017] Optionally, the light conversion layer is a phosphor layer, or the light conversion layer is a quantum dot conversion layer.

[0018] Optionally, the backlight module further includes a packaging layer located between the plurality of light-emitting chips and the first reflective layer, and the packaging layer includes a stacked first sub-layer, second sub-layer, and third sub-layer; the first sub-layer and the third sub-layer are made of inorganic materials, and the second sub-layer is made of organic materials.

[0019] On the other hand, a method for manufacturing a backlight module is provided, the method including: providing a substrate having opposite first and second surfaces; arranging a first reflective layer, a plurality of light conversion units, and a plurality of light-emitting chips on the first surface; wherein, the plurality of light conversion units are arranged in an array on the first surface, and the plurality of light conversion units are connected to the substrate, the first reflective layer is located between adjacent ones of the plurality of light conversion units, the plurality of light-emitting chips are arranged in an array on the first surface, the plurality of light conversion units correspond one-to-one with the plurality of light-emitting chips, the light conversion unit is located on the side of a corresponding one of the light-emitting chips facing the substrate, and the light conversion unit includes a scattering layer, a second reflective layer, and a light conversion layer arranged in sequence along the direction from the substrate to the light-emitting chip; the plurality of light-emitting chips emit light of a first color, the light conversion layer is configured to convert part of the light of the first color into light of a second color and a third color, the second reflective layer is configured to reflect a part of the light of the first color back to the light conversion layer, and transmit a part of the light of the first color, the light of the second color, and the light of the third color to form white light, and the first reflective layer is configured to reflect the white light emitted from the scattering layer to the second surface.

[0020] In another aspect, a liquid crystal display device is provided. The liquid crystal display device includes a liquid crystal display panel and the backlight module as described in any one of the claims. The backlight module provides a light source for the liquid crystal display panel.

[0021] The beneficial effects brought by the technical solutions provided by the present disclosure at least include:

[0022] By providing a second reflective layer on the side of the light conversion layer away from the light-emitting chip, a part of the first color light is reflected back to the light conversion layer, improving the conversion efficiency of the second color light and the third color light, enabling the light conversion layer to convert more second color light and third color light, thereby increasing the proportion of the second color light and the third color light in the emitted white light and improving the color deviation problem of the white light emitted by the backlight module. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 is a schematic structural diagram of a liquid crystal display device provided by an embodiment of the present disclosure;

[0025] Figure 2 is a schematic plan view of a backlight module provided by an embodiment of the present disclosure;

[0026] Figure 3 is a partial schematic plan view of a backlight module provided by an embodiment of the present disclosure;

[0027] Figure 4 is a partial cross-sectional structural diagram of a backlight module provided by an embodiment of the present disclosure, and Figure 4 is Figure 3 a cross-sectional structural diagram along line AA;

[0028] Figure 5 is a cross-sectional structural diagram of a second reflective layer provided by an embodiment of the present disclosure;

[0029] Figure 6 is a spectral diagram corresponding to a second reflective layer provided by an embodiment of the present disclosure;

[0030] Figure 7 is another cross-sectional structural diagram of a second reflective layer provided by an embodiment of the present disclosure;

[0031] Figure 8 is another spectral diagram corresponding to a second reflective layer provided by an embodiment of the present disclosure;

[0032] Figure 9 is a flowchart of a method for manufacturing a backlight module provided by an embodiment of the present disclosure;

[0033] Figures 10 to 18 is a schematic diagram of a manufacturing process of a backlight module provided by an embodiment of the present disclosure.

[0034] Legend:

[0035] 100, backlight module; 200, liquid crystal display panel

[0036] 1, substrate; 10, convex structure; 11, groove; 101, first surface; 102, second surface

[0037] 2, light-emitting chip; 3, light conversion unit; 4, first reflection layer

[0038] 5, encapsulation layer; 6, trace; 7, pad; 8, solder mask layer

[0039] 31, scattering layer; 32, second reflection layer; 33, light conversion layer

[0040] 320, opening (of the second reflection layer)

[0041] 321, first dielectric layer; 322, second dielectric layer Detailed implementation manners

[0042] To make the objectives, technical solutions, and advantages of the present disclosure clearer, the following will further describe in detail the embodiments of the present application with reference to the accompanying drawings.

[0043] The terms used in the embodiments of the present disclosure are only for explaining the embodiments of the present disclosure, rather than aiming to limit the present disclosure. Unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present disclosure should be of the ordinary meaning understood by those of ordinary skill in the art to which the present disclosure belongs. The "first", "second", "third", and similar terms used in the specification and claims of the present patent application do not indicate any order, quantity, or importance, but are only used to distinguish different components. Similarly, the terms such as "a" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. The terms such as "including" or "comprising" mean that the elements or objects appearing before "including" or "comprising" cover the elements or objects listed after "including" or "comprising" and their equivalents, and do not exclude other elements or objects.

[0044] Figure 1 is a schematic structural diagram of a liquid crystal display device provided by an embodiment of the present disclosure. As Figure 1As shown, the liquid crystal display device includes a backlight module 100 and a liquid crystal display panel 200 which are stacked. The liquid crystal display panel 200 is located on the light-emitting side of the backlight module 100, and the shape and size of the liquid crystal display panel 200 generally match those of the backlight module 100. For example, when the liquid crystal display device 200 is applied in fields such as televisions or mobile terminals, the liquid crystal display panel 200 and the backlight module 100 can be set to be rectangular. The liquid crystal display panel 200 is a transmissive display panel, which can modulate the light transmittance, but does not emit light itself. The backlight module 100 is required to provide a light source for the liquid crystal display panel 200 to achieve brightness display. The liquid crystal display panel 200 has a plurality of pixel units arranged in an array, and each pixel unit can independently control the transmittance and color of the light incident on the pixel unit from the backlight module 100, so that the light emitted from all the pixel units forms a displayed image.

[0045] In the embodiment of the present disclosure, the backlight module adopts a direct-lit backlight module, which is used to emit light uniformly within the light-emitting surface, and provides light with sufficient brightness and uniform distribution for the display panel, so that the display panel can display images normally.

[0046] Figure 2 It is a schematic plan view of a backlight module provided by an embodiment of the present disclosure. As Figure 2 shown, the backlight module 100 includes a substrate 1 and a plurality of light-emitting chips 2. The plurality of light-emitting chips 2 are arranged in an array on the first surface 101 of the substrate 1.

[0047] Figure 3 It is a partial schematic plan view of a backlight module provided by an embodiment of the present disclosure, Figure 4 It is a partial schematic cross-sectional view of a backlight module provided by an embodiment of the present disclosure, and Figure 4 is Figure 3 a schematic cross-sectional view along line AA. As Figure 3 and Figure 4 shown, the substrate 1 has opposite first surface 101 and second surface 102, wherein the first surface 101 is away from the light-emitting surface of the backlight module 100, and the second surface 102 is close to the light-emitting surface of the backlight module 100. The backlight module 100 further includes a plurality of light conversion units 3 and a first reflection layer 4.

[0048] Exemplarily, the driving modes of the backlight module 100 in the embodiments of the present disclosure include the following two types: PM (Passive Matrix) and AM (Active Matrix). Among them, passive driving means driving by an external IC (Integrated Circuit) chip. At this time, the backlight module 100 further includes a driving IC (Integrated Circuit), and the driving IC is connected to the substrate 1. The substrate 1 of the backlight module 100 under active driving further includes a TFT (Thin Film Transistor), and is driven by the TFT.

[0049] As Figure 4 shown, a plurality of light conversion units 3 are connected to the substrate 1, and the plurality of light conversion units 3 correspond to the plurality of light-emitting chips 2 one by one. The light conversion unit 3 is located on the side of a corresponding light-emitting chip 2 facing the substrate 1; the light conversion unit 3 includes a scattering layer 31, a second reflection layer 32, and a light conversion layer 33 arranged in sequence along the direction from the substrate 1 to the light-emitting chip 2. The first reflection layer 4 is located between adjacent light conversion units 3.

[0050] The light-emitting chip 2 emits light of a first color, and the light conversion layer 33 is used to convert part of the light of the first color into light of a second color and a third color. After the light of the first color, the light of the second color, and the light of the third color reach the second reflection layer 32, the second reflection layer 32 reflects part of the light of the first color back to the light conversion layer 33 to improve the conversion efficiency of the light of the second color and the third color, and at the same time enables the light of the second color, the light of the third color, and part of the light of the first color to pass through the second reflection layer 32. The scattering layer 31 is used to diffuse the light emitted from the second reflection layer 32. The first reflection layer 4 is used to reflect the light emitted from the scattering layer 31 to the second surface 102 of the substrate 1.

[0051] When the light of the first color, the light of the second color, and the light of the third color are mixed in a certain proportion, white light can be formed. Without the second reflection layer 32, the conversion of the light of the first color by the light conversion layer 33 is not sufficient, which will result in too high a proportion of the light of the first color and too low a proportion of the light of the second color and the light of the third color in the light emitted by the backlight module, resulting in color deviation of the white light emitted by the backlight module. The setting of the second reflection layer 32 can reflect the light of the first color back to the light conversion layer, so that the light conversion layer can convert more light of the second color and the third color, and improve the color deviation problem of the white light emitted by the backlight module.

[0052] Optionally, the first color is blue, and the second and third colors are red and green respectively. Optionally, red light, green light, and blue light can be mixed in a ratio of 1:4.5907:0.0601 to form white light.

[0053] Exemplarily, as Figure 4 shown, the substrate 1 has a plurality of grooves 11, and the plurality of grooves 11 are arranged in an array on the first surface 101 of the substrate. The light conversion unit 3 is located in the plurality of grooves. The light conversion unit 3 being located in the plurality of grooves can make the surface of the light conversion unit 3 close to the light-emitting chip 2 flush with the surface of the first reflective layer 4 close to the light-emitting chip 2, facilitating encapsulation to form a flat encapsulation surface, thereby facilitating the assembly of the light-emitting chip 2 with the flat encapsulation surface.

[0054] Optionally, the substrate 1 does not have a plurality of grooves, the first surface 101 is flat, and the plurality of light conversion units 3 are located on the first surface 101 of the substrate 1.

[0055] Optionally, the substrate 1 can be any transparent substrate, such as a glass substrate, a quartz substrate, a plastic substrate, etc.

[0056] Exemplarily, the light conversion layer 33 is a phosphor layer, or the light conversion layer 33 is a quantum dot conversion layer. Both materials can convert the light of the first color into the light of the second color and the light of the third color.

[0057] In the embodiments of the present disclosure, the second reflective layer 32 has at least one opening. The setting of the opening can prevent the proportion of the light of the first color emitted by the backlight module 100 from being low and reduce the color deviation of the emitted white light. Exemplarily, as Figure 4 shown, the second reflective layer 32 has two openings 320.

[0058] Exemplarily, in the second reflective layer 32, the total area of the positive projection of at least one opening 320 on the first surface 101 of the substrate 1, and the area enclosed by the outer contour of the positive projection of the second reflective layer 32 on the first surface 101 of the substrate 1 have a ratio of 30% to 35%. Setting the proportion of the opening area of the reflective layer to 30 - 35%, such as 31.5% - 33.5%, or for example 1 / 3, can make the ratio of the emitted red, green, and blue light as close as possible to the ideal state, such as 1:4.5907:0.0601, and minimize the color deviation of the formed white light as much as possible.

[0059] Optionally, the shape of the opening is circular, elliptical, square, or rectangular. As Figure 4As shown, the shape of the opening is elongated. For the openings of these shapes, light of the first color can pass through the second reflective layer 32. Since the second reflective layer 32 is relatively thick and contains two dielectric layer materials, there is an etching selectivity, so it is easy to etch openings with a larger area on the second reflective layer 32, and it is not easy to etch openings with a smaller area on the second reflective layer 32.

[0060] Figure 5 It is a schematic cross-sectional structure diagram of a second reflective layer provided by an embodiment of the present disclosure. As Figure 5 shown, the second reflective layer 32 includes a plurality of first dielectric layers 321 and a plurality of second dielectric layers 322 stacked alternately in multiple layers. The refractive index of light of the first dielectric layer 321 is different from that of the second dielectric layer 322. The optical thickness of each layer of the first or second dielectric layer material is designed to be 1 / 4 of the central reflection wavelength, that is, d = λ0 / 4n, where d is the thickness of the first dielectric layer 321 or the second dielectric layer 322, λ0 is the wavelength of the light emitted by the light-emitting chip 2, and n is the refractive index of the first dielectric layer 321 or the second dielectric layer 322. The structure formed by alternately stacking the first dielectric layer 321 and the second dielectric layer 322 with different refractive indices of light has a reflection effect.

[0061] Exemplarily, the first dielectric layer 321 is made of titanium dioxide, and the second dielectric layer 322 is made of silicon dioxide. Among them, titanium dioxide is a high-refractive-index material with a refractive index n≈2.5, and one layer of the first dielectric layer is denoted by H; silicon dioxide material is a low-refractive-index material with a refractive index n≈1.45, and one layer of the second dielectric layer is denoted by L. Moreover, the first dielectric layer 321 made of titanium dioxide has a higher hardness, which can improve the comprehensive performance of the reflective layer. The second dielectric layer 322 made of silicon dioxide is not easily decomposed and absorbed, and has better scattering properties.

[0062] Optionally, the second reflective layer 32 includes a first structural layer and a plurality of second structural layers stacked on the first structural layer. Among them, the first structural layer includes two first dielectric layers 321 stacked, and the second structural layer includes one second dielectric layer 322 and two first dielectric layers 321 stacked. The thickness of the first dielectric layer 321 is 50 nm to 70 nm, and the thickness of the second dielectric layer 322 is 93 nm to 113 nm. Figure 6 It is a spectrogram corresponding to a second reflective layer provided by an embodiment of the present disclosure. As Figure 6As shown in the figure, the reflectivities of the following four types of second reflective layers 32 are respectively simulated and calculated using the commercial software TFCalc: HHLHH, HHLHHLHH, HHLHHLHHLHH, HHLHHLHHLHHLHH. These four types of second reflective layers 32 respectively correspond to the cases where the number of second structural layers is one, two, three, and four. Among them, HH is a half-wavelength spacer layer, and L is a coupling layer. The results of the simulation calculation are as follows: The reflectivities of the third and fourth types of second reflective layers for blue light (at 450 nm) are both greater than 90%, the reflectivity meets the requirements, and the reflectivity of the fourth type of second reflective layer for blue light is higher.

[0063] Exemplarily, as Figure 5 shown, the second reflective layer 32 includes one first structural layer and three second structural layers, that is, the stacking manner of the first dielectric layer 321 and the second dielectric layer 322 in the second reflective layer 32 is HHLHHLHHLHH. From Figure 6 this, it can be known that the ideal reflectivity of this type of second reflective layer 32 for blue light can reach 93.7%, and the cost is lower than that of the second reflective layer composed of one first structural layer and four second structural layers.

[0064] It should be noted that for the half-wavelength spacer layer, that is, two consecutive H layers, when manufacturing, first manufacture one H layer, and then manufacture the second H layer. In an ideal state, when the process conditions are exactly the same, no interface can be observed between the two H layers. When there are differences in the process conditions, equipment such as TEM (Transmission Electron Microscope) can be used to observe the interface between the two H layers.

[0065] Figure 7 is a schematic diagram of the interface structure of another second reflective layer provided by an embodiment of the present disclosure. As Figure 7 shown, the second reflective layer 32 includes a plurality of stacked periodic structures. Among them, the periodic structure includes a stacked first dielectric layer 321 and a second dielectric layer 322. The thickness of the first dielectric layer 321 is 35 nm to 55 nm, and the thickness of the second dielectric layer 322 is 67 nm to 87 nm.

[0066] Figure 8 is the spectrogram corresponding to another second reflective layer provided by an embodiment of the present disclosure. As Figure 8 shown, the reflectivities of the second reflective layer 32 including 1 to 7 periodic structures are respectively simulated and calculated using the commercial software TFCalc. For example, the stacking manner of the second reflective layer 32 including 5 periodic structures is HLHLHLHLHL. From the results, it can be obtained that when the number of periodic structures is 4, 5, 6, and 7, the reflectivities of the second reflective layer 32 for blue light increase in sequence and are all greater than 90%, and the reflectivity meets the requirements.

[0067] Exemplarily, as Figure 7 shown, the second reflective layer 32 includes four stacked periodic structures, that is, the stacking manner of the first dielectric layer 321 and the second dielectric layer 322 in the second reflective layer 32 is: HLHLHLHL. From Figure 8 it can be known that the ideal reflectivity of such a second reflective layer for blue light can reach 93.5%, and the cost is lower than that of other second reflective layers.

[0068] It should be noted that in practical applications, the second reflective layer 32 can be adjusted and weighed accordingly according to the actual product requirements. For example, a second reflective layer with a higher reflectivity and a higher cost can be selected.

[0069] In the embodiments of the present disclosure, referring again to Figure 3 and Figure 4 , the substrate 1 further includes a plurality of convex structures 10. The convex structures 10 are located on the first surface 101 of the substrate and between adjacent light conversion units 3. The first reflective layer 4 is in contact with the convex structures 10. Since the first reflective layer 4 is in contact with the plurality of convex structures 10, the surface of the first reflective layer 4 is uneven and also has a plurality of protrusions. Therefore, compared with the first reflective layer with a flat surface, the plurality of protrusions can make the light emitted from the scattering layer 31 be reflected at multiple angles on the first reflective layer 4, thereby improving the light emission uniformity of the backlight module 100. It should be noted that for the sake of clarity, Figure 4 the plurality of convex structures 10 of the first reflective layer 4 in

[0070] are represented by dotted circles.

[0071] Optionally, the convex structure 10 is a frustum of a cone, a hemisphere or a cone. The plurality of convex structures of these shapes can reflect the light emitted from the scattering layer 31 at multiple angles.

[0072] Exemplarily, the first reflective layer 4 includes a first protective layer, a metal layer and a second protective layer stacked in sequence. Among them, the metal layer can reflect light, and the first protective layer and the second protective layer protect the metal layer to prevent the metal layer from oxidation and the like.

[0073] Optionally, the metal layer is made of silver, and the first protective layer and the second protective layer are made of a transparent material such as indium tin oxide, which not only protects silver from oxidation, but also allows light to pass through the ITO to reach the silver layer and be reflected.

[0074] Exemplarily, as Figure 4As shown, by combining the method of integrating the first reflective layer 4 on the substrate 1 and the method of making a groove 11 on the substrate 1 to arrange the light conversion unit 3, the thickness reduction of the backlight module 100 can be further achieved.

[0075] Exemplarily, as Figure 4 shown, the backlight module 100 further includes a packaging layer 5. The packaging layer 5 is located between the plurality of light-emitting chips 2 and the first reflective layer 4. The orthographic projection of the plurality of light-emitting chips 2 on the first surface 101 of the substrate 1 and the orthographic projection of the first reflective layer 4 on the first surface 101 of the substrate 1 do not coincide at least partially. The packaging layer 5 covers the first surface 101 of the plurality of light conversion units 3 and the first reflective layer 4.

[0076] Optionally, the packaging layer 5 includes a stacked first sub-layer, a second sub-layer, and a third sub-layer; the first sub-layer and the third sub-layer are made of inorganic materials, and the second sub-layer is made of organic materials. The inorganic material can prevent the entry of water and oxygen, and the organic material plays a planarizing role. Optionally, the inorganic material includes SiO2 (silicon oxide), Si3N4 (silicon nitride), SiON (silicon oxynitride). The organic material includes resin and the like.

[0077] Optionally, the scattering layer 31 is made of resin and a plurality of scattering particles, and the plurality of scattering particles are uniformly dispersed in the resin material. The scattering particles include, but are not limited to, metal particles and the like.

[0078] Exemplarily, as Figure 3 and Figure 4 shown, the backlight module 100 further includes a wiring 6 and a pad 7. The wiring 6 and the pad 7 are located on the side of the substrate 1 close to the light-emitting chip 2. The light-emitting chip 2, the pad 7, and the wiring 6 are connected in sequence. The power supply can be provided for the light-emitting chip 2 through the wiring 6. The pad 7 can fix the light-emitting chip 2 to the wiring 6. Optionally, as Figure 3 shown, two groups of wirings 6 and pads 7 are respectively located on both sides of the light conversion unit 3. Optionally, the wiring 6 is made of copper.

[0079] Exemplarily, as Figure 4 shown, the backlight module 100 further includes a solder mask layer 8 for protecting the light-emitting chip 2. Optionally, the solder mask layer 8 is white oil ink. The white oil ink can play a solder mask role and a certain light reflection role, and the white oil ink has the advantages of stable performance, good light reflection, not easily turning yellow for a long time, and high temperature resistance.

[0080] Figure 9 is a flowchart of a method for manufacturing a backlight module provided by an embodiment of the present disclosure. As Figure 9 shown, the method includes:

[0081] In step S1, a substrate is provided, and the substrate has opposite first and second surfaces.

[0082] In step S2, a first reflective layer, a plurality of light conversion units, and a plurality of light-emitting chips are arranged on the first surface.

[0083] Among them, the plurality of light conversion units are arranged in an array on the first surface, and the plurality of light conversion units are connected to the substrate. The first reflective layer is located between adjacent ones of the plurality of light conversion units. The plurality of light-emitting chips are arranged in an array on the first surface. The plurality of light conversion units correspond to the plurality of light-emitting chips one by one. The light conversion unit is located on the side facing the substrate of a corresponding one of the light-emitting chips. The light conversion unit includes a scattering layer, a second reflective layer, and a light conversion layer arranged in sequence along the direction from the substrate to the light-emitting chip.

[0084] The plurality of light-emitting chips emit light of a first color. The light conversion layer is configured to convert part of the light of the first color into light of a second color and light of a third color. The second reflective layer is configured to reflect a part of the light of the first color back to the light conversion layer, and transmit a part of the light of the first color, the light of the second color, and the light of the third color to form white light. The first reflective layer is configured to reflect the white light emitted from the scattering layer to the second surface of the substrate. The first surface is opposite to the second surface.

[0085] Figures 10 to 18 It is a schematic diagram of a manufacturing process of a backlight module provided by an embodiment of the present disclosure. Exemplarily, the manufacturing method of the backlight module will be described in detail below. This manufacturing method can manufacture a backlight module as Figure 4 shown.

[0086] The first step: As Figure 10 shown, a layer of photoresist is coated on the substrate 1, and a photoresist pattern is formed through a photolithography process; then, the surface of the substrate 1 is etched under the cover of the photoresist pattern. Optionally, the substrate is a glass substrate, and the etching method is ICP (Inductively Coupled Plasma) etching.

[0087] The second step: As Figure 11 shown, continue to etch the surface of the substrate 1. At this time, a part of the upper surface of the photoresist is removed, and a plurality of pits are formed on the surface of the substrate 1. Optionally, the etching method is ICP, and the pits are in the shape of an inverted frustum.

[0088] The third step: As Figure 12 shown, continue to etch the surface of the substrate 1 until the photoresist is completely etched. At this time, a plurality of convex structures are formed on the substrate surface. Then, a photoresist pattern is formed again at the position corresponding to the light-emitting chip. Optionally, the etching method is ICP.

[0089] Step 4: As shown in Figure 13 Figure 13 , form an initial first reflective layer 4' on the surface of the substrate 1. Optionally, the initial first reflective layer is formed by sputtering.

[0090] Step 5: As shown in Figure 14 Figure 14 , remove the photoresist, thereby removing a part of the initial first reflective layer on the photoresist to obtain the first reflective layer 4. Optionally, the lift-off process is used to remove the photoresist.

[0091] Step 6: As shown in Figure 15 Figure 15 , form a plurality of grooves 111 by grooving the part of the surface of the substrate 1 where the first reflective layer 4 is not formed. Optionally, with the first reflective layer 4 as a hard mask, the substrate is etched with an etching solution to form the grooves. Optionally, the etching solution is hydrofluoric acid.

[0092] Step 7: As shown in Figure 16 Figure 16 , sequentially form a scattering layer 31, a second reflective layer 32, and a light conversion layer 33 in the grooves 111 to obtain a light conversion unit 3. Then, form a packaging layer 5 on the surfaces of the light conversion unit 3 and the first reflective layer 4. Optionally, the scattering layer 31 is formed by printing. Optionally, an initial second reflective layer is formed on the scattering layer 31, and a series of processes such as photoresist coating, exposure, etching, and stripping are used for patterning to obtain the second reflective layer 32. Optionally, the light conversion layer is formed by printing green and red phosphor layers for realizing white light conversion. Optionally, the packaging layer 5 is formed by deposition.

[0093] Step 8: As shown in Figure 17 Figure 17 , form traces 6 and pads 7 on the packaging layer 5. Optionally, the traces 6 and pads 7 are fabricated by electroplating.

[0094] Step 9: As shown in Figure 18 Figure 18 , fix a plurality of light-emitting chips (LEDs) 2 to other structures and encapsulate them with a solder mask layer 8. Optionally, a plurality of light-emitting chips (LEDs) 2 are fixed to other structures through the traces 6 by using processes such as die bonding and reflow soldering.

[0095] Step 10: Thin the substrate 1 to complete the fabrication of the backlight module as shown in Figure 4 Figure 4 .

[0096] An embodiment of the present disclosure further provides a liquid crystal display device, which includes a liquid crystal display panel 200 and any one of the foregoing backlight modules 100, and the backlight module 100 is used to provide a light source for the liquid crystal display panel.

[0097] Optionally, the liquid crystal display device further includes a power supply circuit, and the power supply circuit is used to supply power to the liquid crystal display panel and the backlight module.

[0098] Exemplarily, the display device provided by the embodiments of the present disclosure may be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigator, etc.

[0099] This liquid crystal display device has the same effect as the aforementioned backlight module, and will not be elaborated herein.

[0100] The above are only optional embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A backlight module, characterized in that, The backlight module (100) includes a substrate (1), a plurality of light-emitting chips (2), a plurality of light conversion units (3), a plurality of convex structures (10), and a first reflective layer (4); The plurality of light-emitting chips (2) are arranged in an array on a first surface (101) of the substrate (1), and the plurality of light-emitting chips (2) emit light of a first color; The plurality of light conversion units (3) are connected to the substrate (1), the plurality of light conversion units (3) correspond to the plurality of light-emitting chips (2) one by one, and the light conversion unit (3) is located on a side of a corresponding one of the light-emitting chips (2) facing the substrate (1); The light conversion unit (3) includes a scattering layer (31), a second reflective layer (32), and a light conversion layer (33) arranged in sequence along a direction from the substrate (1) to the light-emitting chip (2). The light conversion layer (33) is configured to convert part of the light of the first color into light of a second color and light of a third color. The second reflective layer (32) is configured to reflect a part of the light of the first color back to the light conversion layer (33), and transmit a part of the light of the first color, the light of the second color, and the light of the third color to form white light. The second reflective layer (32) has at least one opening (320). The ratio of the total area of the orthographic projection of the at least one opening (320) on the first surface (101) to the area enclosed by the outer contour of the orthographic projection of the second reflective layer (32) on the first surface (101) is 30% to 35%; The first reflective layer (4) is located between adjacent ones of the plurality of light conversion units (3), and is configured to reflect the white light emitted from the scattering layer (31) to a second surface (102) of the substrate (1). The first surface (101) and the second surface (102) are opposite to each other; The plurality of convex structures (10) are located on the first surface (101) and between adjacent ones of the plurality of light conversion units (3). The first reflective layer (4) is in contact with the convex structures (10). The convex structures (10) are frustum cones, hemispheres, or cones.

2. The backlight module according to claim 1, wherein The second reflective layer (32) includes a plurality of first dielectric layers (321) and a plurality of second dielectric layers (322) stacked alternately in multiple layers. The refractive index of the first dielectric layer (321) is different from the refractive index of the second dielectric layer (322).

3. The backlight module according to claim 2, wherein The second reflective layer (32) includes a first structural layer and a plurality of second structural layers stacked on the first structural layer. The first structural layer includes two of the first dielectric layers (321) stacked, and the second structural layer includes one of the second dielectric layers (322) and two of the first dielectric layers (321) stacked; The thickness of the first dielectric layer (321) is 50 nm to 70 nm, and the thickness of the second dielectric layer (322) is 93 nm to 113 nm.

4. The backlight module according to claim 2, wherein, The second reflective layer (32) includes a plurality of stacked periodic structures, where each periodic structure includes a stacked one of the first dielectric layer (321) and a second dielectric layer (322); The thickness of the first dielectric layer (321) is 35 nm to 55 nm, and the thickness of the second dielectric layer (322) is 67 nm to 87 nm.

5. The backlight module according to any one of claims 2 to 4, characterized in that The first dielectric layer (321) is made of titanium dioxide, and the second dielectric layer (322) is made of silicon dioxide.

6. The backlight module according to claim 1, wherein, The shape of the opening (320) is circular, oval, square or rectangular.

7. The backlight module according to any one of claims 1 to 4 and claim 6, characterized in that, The first reflective layer (4) includes a first protective layer, a metal layer, and a second protective layer stacked in sequence.

8. The backlight module according to any one of claims 1 to 4 and claim 6, characterized in that, The substrate (1) has a plurality of grooves (11), and the plurality of grooves (11) are arranged in an array on the first surface (101), and the plurality of light conversion units (3) are located in the plurality of grooves (11).

9. The backlight module according to any one of claims 1 to 4 and claim 6, wherein The light conversion layer (33) is a phosphor layer, or the light conversion layer (33) is a quantum dot conversion layer.

10. The backlight module according to any one of claims 1 to 4 and claim 6, characterized in that, The backlight module (100) further includes a packaging layer (5), and the packaging layer (5) is located between the plurality of light-emitting chips (2) and the first reflective layer (4). The packaging layer (5) includes a stacked first sub-layer, a second sub-layer, and a third sub-layer; The first sub-layer and the third sub-layer are made of inorganic materials, and the second sub-layer is made of organic materials.

11. A manufacturing method of a backlight module, characterized in that, The method includes: Providing a substrate having opposite first and second surfaces; Arranging a first reflective layer, a plurality of light conversion units, a plurality of light-emitting chips, and a plurality of raised structures on the first surface; Among them, the plurality of light conversion units are arranged in an array on the first surface, and the plurality of light conversion units are connected to the substrate. The first reflective layer is located between the adjacent plurality of light conversion units. The plurality of light-emitting chips are arranged in an array on the first surface. The plurality of light conversion units correspond to the plurality of light-emitting chips one by one. The light conversion unit is located on the side of a corresponding light-emitting chip facing the substrate. The light conversion unit includes a scattering layer, a second reflective layer, and a light conversion layer arranged in sequence along the direction from the substrate to the light-emitting chip; The plurality of light-emitting chips emit light of a first color. The light conversion layer is used to convert part of the light of the first color into light of a second color and a third color. The second reflective layer is used to reflect a part of the light of the first color back to the light conversion layer, and transmit a part of the light of the first color, the light of the second color, and the light of the third color to form white light. The second reflective layer has at least one opening. The ratio of the total area of the positive projection of the at least one opening on the first surface to the area enclosed by the outer contour of the positive projection of the second reflective layer on the first surface is 30% to 35%. The first reflective layer is used to reflect the white light emitted from the scattering layer to the second surface; The plurality of convex structures are located on the first surface and between adjacent ones of the plurality of light conversion units. The first reflective layer is in contact with the convex structures, and the convex structures are frustum cones, hemispheres or cones.

12. A liquid crystal display device, characterized in that, The liquid crystal display device includes a liquid crystal display panel and a backlight module as described in any one of claims 1 to 10, and the backlight module (100) provides a light source for the liquid crystal display panel (200).

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