LED lamp bead, backlight module and display device

Abstract

The application discloses an LED lamp bead, a backlight module and a display device, relates to the technical field of display, and discloses an LED lamp bead, which comprises a blue light LED wafer, a fluorescent layer arranged on the light emitting side of the blue light LED wafer, and a diffusion layer arranged on the light emitting side of the fluorescent layer, wherein the middle part of the diffusion layer is recessed towards the light entering side of the diffusion layer; a support provided with a containing groove, wherein the blue light LED wafer and the fluorescent layer are arranged in the containing groove, and the diffusion layer covers the opening of the containing groove to form a closed container. The application can effectively protect the fluorescent layer, thereby supporting the improvement of the stability of the LED lamp bead.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to an LED lamp bead, a backlight module, and a display device. Background Technology

[0002] A light-emitting diode (LED) is a compound semiconductor device composed of elements such as gallium (Ga), arsenic (As), and phosphorus (P). Its light-emitting mechanism is based on the energy released when electrons and holes recombine in a PN junction, radiating visible light in the form of photons. With its advantages of high efficiency, energy saving, long lifespan, environmental friendliness, and low blue light hazard, LED technology is considered a major breakthrough in the lighting field and has been widely used in circuit indicators, digital displays, and various lighting systems.

[0003] Phosphors play a crucial role in the manufacturing process of LEDs, especially white LEDs. By coating blue LED chips with phosphors, some blue light is absorbed and converted into yellow or red light, which mixes with the remaining blue light to form white light. However, in practical applications, the phosphor layer is quite sensitive and easily affected by environmental factors. Conventional packaging structures often fail to provide sufficient protection, leading to decreased light color stability and shortened device lifespan, becoming one of the key factors restricting further improvements in LED performance. Utility Model Content

[0004] The main objective of this application is to provide an LED chip, a backlight module, and a display device. This application can effectively protect the phosphor layer, thereby supporting the improvement of the stability of the LED chip.

[0005] To achieve the above objectives, this application provides an LED lamp bead, which includes:

[0006] Blue LED chips;

[0007] A fluorescent layer is disposed on the light-emitting side of the blue LED chip;

[0008] A diffusion layer is disposed on the light-emitting side of the fluorescent layer, and a recess is formed in the middle portion of the diffusion layer facing the light-incident side of the diffusion layer;

[0009] The support has a receiving groove, in which the blue LED chip and the phosphor layer are both disposed. The diffusion layer covers the opening of the receiving groove to form a sealed container.

[0010] In one embodiment, the recess depth of the diffusion layer is 30-50 μm, and the edge thickness of the diffusion layer is 80-100 μm.

[0011] In one embodiment, diffusion particles are added to the diffusion layer, including PET, PMMA, PP, PS, MS, SiO2, or TiO2.

[0012] In one embodiment, the fluorescent layer includes:

[0013] First fluorescent layer;

[0014] The second fluorescent layer is disposed on the light-emitting side of the first fluorescent layer;

[0015] The luminescent material in the first fluorescent layer is different from the luminescent material in the second fluorescent layer. The luminescent material in the second fluorescent layer is KSF phosphor.

[0016] In one embodiment, the luminescent material of the first fluorescent layer includes: β-SiAlON phosphor, chlorosilicate phosphor, YAG phosphor, TAG phosphor, or Ca-α-SiAlON phosphor.

[0017] In one embodiment, the thickness of the first fluorescent layer is 150–200 μm;

[0018] The thickness of the second fluorescent layer is 80–100 μm.

[0019] In one embodiment, the LED packaging structure further includes a protective layer disposed around the blue LED chip.

[0020] In one embodiment, the thickness of the protective layer is 80–100 μm.

[0021] In addition, to achieve the above objectives, this application also proposes a backlight module, which includes LED beads as described above.

[0022] In addition, to achieve the above objectives, this application also proposes a display device, which includes LED beads as described above, or a backlight module as described above.

[0023] One or more technical solutions proposed in this application have at least the following technical effects: An LED chip is provided, comprising: a blue LED chip, a phosphor layer disposed on the light-emitting side of the blue LED chip, and a diffusion layer disposed on the light-emitting side of the phosphor layer, wherein the middle portion of the diffusion layer is recessed towards the light-incident side of the diffusion layer; a support with a receiving groove, wherein the blue LED chip and the phosphor layer are both disposed within the receiving groove, and the diffusion layer covers the opening of the receiving groove to form a sealed container. In this embodiment, the sealed container formed by the diffusion layer and the support effectively prevents external moisture from entering, thereby effectively protecting the humidity-sensitive phosphor layer and the blue LED chip. The diffusion layer can also provide heat insulation to a certain extent, while helping to disperse heat, avoiding local overheating, and ensuring the reliability of the LED chip. Simultaneously, the recessed middle portion of the diffusion layer towards the light-incident side of the diffusion layer can change the direction of the light, making the light more evenly distributed over a wider angle range. This helps reduce the central hot spot effect and makes the light output softer and more uniform. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the LED lamp bead involved in the embodiments of this application. Figure 1 ;

[0025] Figure 2 This is a schematic diagram of the structure of the LED lamp bead involved in the embodiments of this application. Figure 2 ;

[0026] Figure 3 This is a schematic diagram of a conventional LED chip.

[0027] Figure 4 This is the emission spectrum of the LED lamp bead involved in the embodiments of this application;

[0028] Figure 5 This is a scanning electron microscope image of KSF phosphor.

[0029] Figure 6 This is a schematic diagram of the KSF phosphor and inorganic passivation layer involved in the embodiments of this application;

[0030] Figure 7 The images shown are scanning electron microscope (SEM) images of the KSF phosphor and inorganic passivation layer involved in the embodiments of this application.

[0031] Figure 8 This is a schematic diagram of the backlight module in an embodiment of this application;

[0032] Figure 9 This is a schematic diagram of the display device in an embodiment of this application.

[0033] Explanation of reference numerals in the attached figures

[0034] 101. Wafer; 102. Mixed phosphor layer;

[0035] 20. LED beads; 21. Blue LED chip; 22. Protective layer; 23. Phosphor layer;

[0036] 231. First fluorescent layer; 232. Second fluorescent layer; 24. Diffusion layer; 25. Scaffold;

[0037] 200. Backlight module; 210. Back panel; 220. Reflective film;

[0038] 230. Diffuser plate; 240. Optical functional film;

[0039] 300. Display panel; 400. Display device.

[0040] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0042] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the LED beads, backlight module, and display device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of essentially the same structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0043] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0044] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0045] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0046] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0047] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0048] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0049] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the technical solution of this application is further described below in conjunction with the accompanying drawings and embodiments. However, this application is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims made in this application.

[0050] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0051] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0052] In related technologies, phosphor layers are relatively sensitive and easily affected by environmental factors, and conventional packaging structures often fail to provide sufficient protection for them, resulting in decreased light color stability and shortened device lifespan, which has become one of the key factors restricting further improvement of LED performance.

[0053] In this embodiment, an LED bead is provided, comprising: a blue LED chip, a phosphor layer disposed on the light-emitting side of the blue LED chip, and a diffusion layer disposed on the light-emitting side of the phosphor layer, wherein the middle portion of the diffusion layer is recessed towards the light-incident side of the diffusion layer; and a support with a receiving groove, wherein the blue LED chip and the phosphor layer are both disposed within the receiving groove, and the diffusion layer covers the opening of the receiving groove to form a sealed container. In this embodiment, the sealed container formed by the diffusion layer and the support effectively prevents external moisture from entering, thereby effectively protecting the humidity-sensitive phosphor layer and the blue LED chip. The diffusion layer also provides a certain degree of heat insulation, helps to disperse heat, avoids local overheating, and ensures the reliability of the LED bead. Simultaneously, the recessed middle portion of the diffusion layer towards the light-incident side changes the direction of the light, making the light more evenly distributed over a wider angle range. This helps reduce the central hot spot effect and makes the light output softer and more uniform.

[0054] Based on this, the first aspect of the embodiments of this application provides an LED lamp bead, referring to... Figure 1The LED bead 20 includes: a blue LED chip 21, a protective layer 22, a phosphor layer 23, a diffusion layer 24, and a support 25. The protective layer 22 is disposed around the blue LED chip 21, the phosphor layer 23 is disposed on the light-emitting side of the protective layer 22, and the diffusion layer 24 is disposed on the light-emitting side of the phosphor layer, with the middle portion of the diffusion layer 24 forming a recess towards the light-incident side of the diffusion layer 24. The support 25 is provided with a receiving groove, in which the blue LED chip 21, the protective layer 22, and the phosphor layer 23 are all disposed. The diffusion layer 24 covers the opening of the receiving groove to form a sealed container.

[0055] In this embodiment, the diffuser layer 24 and the support 25 form a sealed container, effectively preventing external moisture from entering, thereby effectively protecting the humidity-sensitive phosphor layer 23 and blue LED chip 21. The diffuser layer 24 also provides some heat insulation, helping to disperse heat and prevent localized overheating, ensuring the reliability of the LED chip 20. Simultaneously, the central portion of the diffuser layer 24 has a recess on the light-incident side, which alters the direction of light, resulting in a more uniform light distribution over a wider angle range. This helps reduce the central hotspot effect and makes the light output softer and more uniform.

[0056] Alternatively, the material of the bracket 25 may be fiberglass composite material and / or epoxy resin composite material.

[0057] Optionally, the depth of the receiving groove of the support 25 is approximately 400 μm.

[0058] In one feasible embodiment, diffusion particles are added to the diffusion layer 24. The diffusion particles include any one of PET, PMMA, PP, PS, MS, SiO2, and TiO2. Due to the presence of the diffusion particles, light can be better mixed with different colors after multiple reflections and refractions, which helps to improve color consistency and accuracy. At the same time, the diffusion particles can scatter light, thereby reducing hot spots in the light source (i.e., some areas are brighter than others), making the light emitted from the LED beads 20 more uniform.

[0059] In one feasible embodiment, a recess is formed in the middle portion of the diffuser layer 24 facing the light-incident side of the diffuser layer. This recess can change the direction of the light, making the light more evenly distributed over a wider angular range. This helps reduce the central hot spot effect and can make the light output softer and more uniform.

[0060] Optionally, the depth of the recess in the middle part of the diffusion layer 24 is 30-50 μm, and the thickness of the edge of the diffusion layer 24 is 80-100 μm.

[0061] In one feasible implementation, refer to Figure 2 The fluorescent layer 23 includes a first fluorescent layer 231 and a second fluorescent layer 232, wherein the second fluorescent layer 232 is disposed on the light-emitting side of the first fluorescent layer 231; the luminescent material in the first fluorescent layer 231 is different from the luminescent material in the second fluorescent layer 232, and the luminescent material of the second fluorescent layer 232 is KSF phosphor.

[0062] KSF phosphor, namely K2SiF6:Mn 4+ KSF phosphors, belonging to the fluoride-based family, emit very pure red light with an extremely narrow emission peak. This makes them excellent for applications requiring high color rendering index and accurate color reproduction. Furthermore, KSF phosphors have very high blue light absorption efficiency and can effectively convert blue light into red light, contributing to high-quality white light output. However, one of the biggest drawbacks of KSF phosphors is their susceptibility to moisture absorption and hydrolysis. This can lead to material decomposition and potentially release corrosive HF gas, damaging LED chips. At higher temperatures, KSF phosphors may also undergo structural changes or decomposition. Additionally, Mn... 4+ Ions may be reduced to the non-luminescent state of Mn under high-intensity blue light irradiation. 3+ Or other valence states, leading to a decrease in permanent luminous efficiency.

[0063] In related technologies, refer to Figure 3 Conventional LED chips primarily consist of a chip 101 that excites blue light, which is then combined with a mixed phosphor layer 102 containing green and red phosphors to excite green and red light, resulting in white light. However, the excitation spectrum of red phosphors (e.g., KSF phosphors) is relatively narrow, mainly concentrated within a specific wavelength range of blue light. If the wavelength of the blue light exceeds this optimal absorption range, or if the intensity of the blue light is too high, the red phosphor may have difficulty effectively converting all the blue light into red light, thus making it more prone to blue light interference and affecting the stability of the LED chip.

[0064] In this embodiment, by setting up a vertical multilayer structure of blue LED chip 21, first phosphor layer 231 and second phosphor layer 232, the blue light excited by blue LED chip 21 will be preferentially absorbed and converted by the first phosphor layer 231, which has a wide excitation spectrum and good high light intensity tolerance, thereby reducing the amount of blue light reaching the second phosphor layer 232. This effectively alleviates the light-induced decay of KSF phosphor in the second phosphor layer 232 due to blue light interference, and improves the optical stability and reliability of the overall LED packaging structure.

[0065] The blue LED chip 21 is one of the core components of the LED bead 20, playing a crucial role in converting electrical energy into light energy. It is primarily made of semiconductor materials, releasing energy through the recombination of electrons and holes to generate photons, which in turn emit visible light or electromagnetic radiation of other wavelengths. Commonly used semiconductor materials for the blue LED chip 21 include gallium arsenide (GaAs), gallium phosphide (GaP), and gallium nitride (GaN), which emit blue light of a specific wavelength based on the electroluminescence effect of a PN junction.

[0066] Optionally, the blue LED chip 21 is an LED chip or a mini LED chip.

[0067] For example, the blue LED chip 21 is a flip chip. A flip chip has the active side of the chip facing down and directly contacting the packaging substrate. This structure allows the heat generated by the chip to be quickly conducted to the substrate and dissipated through a heat dissipation system. Compared with traditional packaging technology, flip chip packaging does not require wire bonding. The direct connection between the chip and the substrate greatly shortens the heat conduction path and reduces thermal resistance.

[0068] Mini LED chips represent an advancement in LED technology, featuring smaller (e.g., 50–200 μm) LED chips. Compared to traditional LED chips, Mini LED chips are smaller, allowing for thinner displays.

[0069] In one feasible embodiment, the blue LED chip 21 emits light in the wavelength range of 445–460 nm.

[0070] The protective layer 22 is used to cover and protect the pads, electrodes and other components in the LED bead 20, and can also stabilize the blue LED chip 21.

[0071] Optionally, the material of the protective layer 22 includes any one of silicone, epoxy resin and polyurethane resin.

[0072] In one feasible embodiment, the thickness of the protective layer 22 is 80 to 100 μm; for example, the thickness of the protective layer 22 is 80 μm, 82 μm, 84 μm, 86 μm, 88 μm, 90 μm, 92 μm, 94 μm, 96 μm, 98 μm, 100 μm, etc.

[0073] Optionally, the thickness of the protective layer 22 can be greater than the height of the blue LED chip 21, thereby completely enclosing the blue LED chip 21 and providing comprehensive physical and chemical protection for the blue LED chip 21, preventing moisture, dust and other contaminants from entering, and improving long-term reliability and stability.

[0074] Optionally, the thickness of the protective layer 22 can be less than or equal to the height of the blue LED chip 21, thus partially enclosing the blue LED chip 21. The first phosphor layer 231 located on the light-emitting side of the protective layer 22 can directly contact the blue LED chip 21, allowing the light emitted by the blue LED chip 21 to be directly transmitted to the first phosphor layer 231, reducing reflection loss due to additional optical interfaces, such as the protective layer 22, thereby improving light output efficiency.

[0075] Optionally, the thickness of the blue LED chip 21 is about 200um, for example, the thickness of the blue LED chip 21 is 200um.

[0076] The first fluorescent layer 231 is disposed on the light-emitting side of the protective layer 22 and may or may not be in contact with the blue LED chip 21. The luminescent material in the first fluorescent layer 231 is different from the luminescent material in the second fluorescent layer 232; for example, since the luminescent material of the second fluorescent layer 232 is KSF phosphor, which emits wavelengths of 620-660 nm when excited by the blue LED chip 21, the first fluorescent layer 231 may be selected to emit luminescent materials with wavelengths of 520-575 nm when excited by the blue LED chip 21, corresponding to the green-yellow-green-yellow region in the visible spectrum. It has a higher absorption and conversion efficiency for blue light, and compared with the fluorescent layer that can excite red light, the first fluorescent layer 231 can exhibit better stability under long-term blue light irradiation.

[0077] The second fluorescent layer 232 is disposed on the light-emitting side of the first fluorescent layer 231, and its emission wavelength is 620-660 nm, which belongs to the red region of the visible spectrum. A red luminescent material, such as KSF phosphor, is added to the second fluorescent layer 232. KSF phosphor needs to convert high-energy blue light into low-energy red light, which leads to significant energy loss. This unused energy is released as heat, thus increasing the local temperature of the KSF phosphor and affecting its stability and lifetime. Simultaneously, KSF phosphor typically has a narrow excitation and emission spectrum, meaning it is more sensitive to changes in blue light wavelength. Any small deviation can lead to a significant decrease in absorption efficiency, increasing the proportion of unconverted blue light and further exacerbating the "blue light interference" phenomenon. To achieve ideal color balance and color rendering index, the KSF phosphor in the second phosphor layer 232 typically requires a high doping concentration. However, excessively high concentration means more energy is converted into heat. Combined with the poor heat dissipation of KSF phosphor itself, this can easily lead to localized overheating under high current driving, accelerating material aging. Therefore, to ensure device reliability, devices with added KSF phosphor need to be driven with low current, but this will affect the luminous efficacy of the light-emitting device. In this embodiment, the first phosphor layer 231 uses a material with high blue light absorption capacity and good thermal stability, which can preferentially absorb and convert most of the high-energy radiation from the blue LED chip 21. Therefore, it can reduce the amount of blue light reaching the second phosphor layer 232, reducing the energy load that the KSF phosphor needs to handle. Since most of the blue light is absorbed by the first phosphor layer 231 and converted into light of other wavelengths, the generated heat is also dispersed throughout the entire encapsulation structure, rather than concentrated on the KSF phosphor. This helps to avoid localized high temperatures in the second phosphor layer 232 and slows down its aging rate due to overheating. Meanwhile, through the effective function of the first fluorescent layer, the LED bead 20 can ensure the safe working environment of KSF phosphor even under high current, thereby ensuring the reliability of the LED bead 20 while fully utilizing its luminous efficiency.

[0078] In one feasible embodiment, the thickness of the first phosphor layer 231 is greater than the thickness of the second phosphor layer 232. One of the functions of the first phosphor layer 231 is to efficiently absorb most of the high-energy blue light from the blue LED chip 21 and convert it into light of other wavelengths (such as yellow-green light). To achieve this goal, sufficient material volume is required to ensure that as much blue light as possible is absorbed rather than penetrates to the second phosphor layer 232. Therefore, increasing the thickness of the first phosphor layer 231 helps reduce the possibility of unabsorbed blue light directly penetrating to the second phosphor layer 232, avoiding the problem of accelerated aging of the second phosphor layer 232 due to excessive blue light exposure. At the same time, heat is generated during the conversion of blue light into other wavelengths, and the thicker first phosphor layer 231 can act as an effective thermal buffer, helping to disperse the heat generated by the blue light conversion and preventing the formation of local hot spots. This not only protects the red emitting material from high-temperature damage but also helps maintain the temperature uniformity of the entire encapsulation structure.

[0079] In one feasible embodiment, the thickness of the first fluorescent layer 231 is 150 to 200 μm; for example, the thickness of the first fluorescent layer 231 is 150 μm, 155 μm, 160 μm, 165 μm, 170 μm, 175 μm, 180 μm, 185 μm, 190 μm, 195 μm, 200 μm, etc.

[0080] Optionally, the first fluorescent layer 231 is made of a mixture of a luminescent material and a matrix material, and the matrix material can be silicone, epoxy resin, etc.

[0081] In one feasible embodiment, the thickness of the second fluorescent layer 232 is 80 to 100 μm; for example, the thickness of the second fluorescent layer 232 is 80 μm, 82 μm, 84 μm, 86 μm, 88 μm, 90 μm, 92 μm, 94 μm, 96 μm, 98 μm, 100 μm, etc.

[0082] Optionally, the second fluorescent layer 232 is made of a mixture of a luminescent material and a matrix material, and the matrix material can be silicone, epoxy resin, etc.

[0083] In one feasible embodiment, the luminescent material of the first fluorescent layer 231 includes any one of β-SiAlON phosphor, chlorosilicate phosphor, YAG phosphor, TAG phosphor, and Ca-α-SiAlON phosphor.

[0084] β-SiAlON phosphor, i.e. β-Sialon:Eu 2+ It is a green narrow-band phosphor, considered one of the ideal materials for manufacturing wide color gamut LED backlights due to its narrow half-width and excellent stability. It has high luminous efficiency, which can significantly improve the lumen efficiency of the backlight.

[0085] Chlorosilicate phosphor, namely Ca8Mg(SiO4)4Cl2:Eu 2+ With excellent spectral characteristics, this phosphor can provide a high colorimetric index.

[0086] YAG (yttrium aluminum garnet) phosphors have good thermal stability and high luminous efficiency, and can maintain stable performance in high-temperature environments.

[0087] TAG (terbium aluminum garnet) phosphor is an important yellow phosphor that typically contains terbium as an activator, emitting a bright yellow light. Due to its unique crystal structure and abundant cation sites, TAG phosphor has advantages over YAG phosphor in certain applications.

[0088] Ca-α-SiAlON phosphor has the characteristics of high hardness, good wear resistance and corrosion resistance.

[0089] In this embodiment, the luminescent material of the first phosphor layer 231 includes any one of β-SiAlON phosphor, chlorosilicate phosphor, YAG phosphor, TAG phosphor, and Ca-α-SiAlON phosphor. All of the above luminescent materials have excellent thermal and chemical stability and can maintain good luminescent performance under high temperature conditions. Therefore, they can preferentially absorb and convert most of the high-energy radiation from the blue LED chip 21, thereby reducing the amount of blue light reaching the second phosphor layer 232. This effectively alleviates the light-induced decay of the KSF phosphor in the second phosphor layer 232 due to blue light interference and improves the optical stability and reliability of the overall LED packaging structure.

[0090] In one feasible embodiment, the luminescent material of the second fluorescent layer 232 is KSF phosphor.

[0091] In this embodiment, by making reasonable use of the advantages of the above-mentioned fluorescent materials and combining them with the effective protective function of the first fluorescent layer 231, the potential of each fluorescent material can be maximized while overcoming their respective shortcomings, ensuring that the LED bead 20 has both high luminous efficiency and long-term reliability.

[0092] For example, the luminescent material in the first fluorescent layer 231 can be β-SiAlON phosphor, and the luminescent material in the second fluorescent layer 232 can be KSF phosphor. β-SiAlON phosphor has a stable silicon nitride matrix, in which the Si-N bonds are very strong, which endows the material with good thermal and chemical stability. In contrast, KSF phosphor belongs to the fluoride series, and its crystal structure is relatively more fragile. It is prone to deterioration under high temperature or high humidity environments, and its stability under blue light excitation is also weaker than that of β-SiAlON phosphor. Therefore, in this embodiment, by setting up a vertical multilayer structure, the blue light excited by the blue LED chip 21 will be preferentially absorbed and consumed by the first fluorescent layer 231, which has efficient absorption capacity for blue light and good thermal stability, thereby reducing the amount of blue light reaching the second fluorescent layer 232 and reducing the energy load that the red luminescent material needs to handle. Since most of the blue light is absorbed by the first phosphor layer 231 and converted into light of other wavelengths, the generated heat is also dispersed throughout the entire encapsulation structure, rather than concentrated on the red light-emitting material. This helps to prevent localized high temperatures in the second phosphor layer 232 and slows down its aging rate due to overheating. Simultaneously, the effective function of the first phosphor layer ensures a safe operating environment for the red light-emitting material even under high current, thus guaranteeing the reliability of the LED chip 20 while maximizing its luminous efficacy.

[0093] For example, the luminescent material in the first phosphor layer 231 can be YAG phosphor, and the luminescent material in the second phosphor layer 232 can be KSF phosphor. YAG phosphor is known for its excellent chemical stability and is not easily affected by moisture and other chemicals. In contrast, KSF phosphor contains fluorides, which easily react with moisture in the air, causing damage to its crystal structure, thus affecting luminous efficiency and color purity. Furthermore, its stability under blue light excitation is weaker than that of YAG phosphor. Therefore, this embodiment of the application uses a vertical multilayer structure so that the blue light excited by the blue LED chip 21 is preferentially absorbed and consumed by the first phosphor layer 231, which has high absorption capacity for blue light and good thermal stability. This reduces the amount of blue light reaching the second phosphor layer 232 and reduces the energy load that the red luminescent material needs to handle. Since most of the blue light is absorbed by the first phosphor layer 231 and converted into light of other wavelengths, the generated heat is also dispersed throughout the entire encapsulation structure, rather than concentrated on the red luminescent material. This helps to avoid localized high temperatures in the second phosphor layer 232 and slows down its aging rate due to overheating. Meanwhile, through the effective function of the first fluorescent layer, the LED bead 20 can ensure a safe working environment for the red light-emitting material even under high current, thereby ensuring the reliability of the LED bead 20 while fully utilizing its luminous efficiency.

[0094] Optionally, refer to Figure 2 In this embodiment, the LED bead 20 adopts a vertical multilayer structure design. The blue light emitted by the blue LED chip 21 first reaches the first phosphor layer 231. The luminescent material in the first phosphor layer 231 absorbs part of the blue light and excites a green, yellow-green, or yellow light band. The remaining blue light reaches the second phosphor layer 232. The luminescent material in the second phosphor layer 232 absorbs part of the blue light and excites a red light band. Further, the three colors of light are mixed in the top diffusion layer 24 to become white light emitted, and the emitted spectrum is as follows: Figure 4 As shown.

[0095] Alternatively, compared to Figure 3 The conventional LED beads shown in this application embodiment can effectively control the blue light intensity of the second fluorescent layer 232 by setting the thickness of the first fluorescent layer 231. This can meet the excitation requirements and avoid the stability problem caused by excessive blue light.

[0096] In conventional techniques, the active ingredient in KSF phosphor is [MnF6]. 2- In high-temperature and high-humidity environments, KSF phosphors are highly susceptible to hydrolysis. The hydrolysis product, hydrofluoric acid, is highly corrosive and causes irreversible damage to the chip, pads, and electrodes. Simultaneously, the luminous efficiency of KSF phosphors drops drastically in high-temperature environments, thus requiring only a low current of around 550mA for driving, necessitating additional optical gain films for compensation to achieve ultra-high brightness. In contrast, the luminescent material in the first phosphor layer 231 of this embodiment exhibits better stability. Encasing the blue LED chip 21 with the first phosphor layer 231 material provides a degree of heat insulation, ensuring the thermal stability of the second phosphor layer 232 material. Therefore, it can be driven with a high current of over 700mA, increasing brightness by approximately 30% and significantly reducing manufacturing costs. Furthermore, the second phosphor layer 232 material is disposed between the first phosphor layer 231 and the diffusion layer 24, thus providing a degree of insulation against ambient moisture and ensuring the stability of the second phosphor layer 232 material.

[0097] In one feasible embodiment, an inorganic passivation layer is disposed on the surface of the luminescent material of the first fluorescent layer 231, and the thickness of the inorganic passivation layer is 30-50 nm.

[0098] In one feasible embodiment, an inorganic passivation layer is disposed on the surface of the luminescent material of the second fluorescent layer 232, and the thickness of the inorganic passivation layer is 30-50 nm.

[0099] Optionally, the inorganic passivation layer can effectively prevent harmful substances in the external environment, such as moisture and oxygen, from contacting the luminescent material, thereby reducing the aging and degradation of phosphors (e.g., KSF phosphors) and enhancing the chemical and thermal stability of the luminescent material.

[0100] Optionally, the thickness of the inorganic passivation layer can be 30nm, 32nm, 34nm, 36nm, 38nm, 40nm, 42nm, 44nm, 46nm, 48nm, 50nm, etc. An excessively thin passivation layer may not provide a sufficient barrier to prevent the erosion of the luminescent material by moisture, oxygen, etc., in the external environment, leading to accelerated aging of the luminescent material. An excessively thick passivation layer increases the scattering and absorption of light as it passes through, thereby reducing the amount of light ultimately emitted to the outside and lowering the luminous efficiency. Therefore, in this embodiment, the thickness of the inorganic passivation layer is determined to be 30–50nm.

[0101] In one feasible embodiment, the material of the inorganic passivation layer includes barium fluoride or calcium fluoride.

[0102] For example, the luminescent material of the second fluorescent layer 232 is KSF phosphor, and an inorganic passivation layer composed of barium fluoride is disposed on the surface of the KSF phosphor. KSF phosphor is a tetravalent manganese ion (Mn) phosphor. 4+ Doped fluoride red phosphor semiconductors, such as Figure 5 As shown, its surface exhibits significant lattice defects, which not only affect the stimulated light efficiency but also allow water vapor to easily penetrate, leading to the loss of the effective component [MnF6]. 2- Hydrolysis leads to failure. To address this issue, this application's embodiments generate a barium fluoride inorganic passivation layer on the surface of the KSF crystal. KSF phosphor itself is a fluoride, and its crystals contain free fluoride ions (F₂). - When there are sufficient barium ions Ba 2+ When adsorbed onto the surface of KSF crystals, under a nitrogen atmosphere and constant temperature of approximately 800℃ for 3–4 hours, Ba can be induced on the crystal surface. 2+ With free state F - Barium fluoride (BaF2) forms and adheres to the surface of KSF crystals, forming a dense inorganic passivation layer with a thickness of approximately 30–50 nm. Figure 6 and Figure 7 As shown, BaF2 exhibits high light transmittance and low dispersion across the entire spectrum, unaffecting the blue light absorption and red light emission of KSF phosphors. Furthermore, BaF2 possesses lattice parameters similar to KSF, allowing for lattice matching to passivate surface defects in KSF crystals, thereby improving the excitation efficiency of KSF phosphors by more than 5%. BaF2 is also hydrophobic, effectively isolating environmental moisture and preventing the hydrolysis visual quality issues frequently encountered with traditional wide-gamut LEDs. In high-temperature environments, BaF2 can dissipate heat through lattice resonance, ensuring that KSF phosphor crystals maintain high activity and excitation efficiency even under extreme high-temperature conditions.

[0103] A second aspect of this application provides a backlight module, which includes LED beads as described above.

[0104] Optionally, the LED beads include:

[0105] Blue LED chips;

[0106] A fluorescent layer is disposed on the light-emitting side of the blue LED chip;

[0107] A diffusion layer is disposed on the light-emitting side of the fluorescent layer, and a recess is formed in the middle portion of the diffusion layer facing the light-incident side of the diffusion layer;

[0108] The support has a receiving groove, in which the blue LED chip and the phosphor layer are both disposed. The diffusion layer covers the opening of the receiving groove to form a sealed container.

[0109] Optionally, the recess depth of the diffusion layer is 30–50 μm, and the edge thickness of the diffusion layer is 80–100 μm.

[0110] Optionally, the diffusion layer contains diffusion particles, including PET, PMMA, PP, PS, MS, SiO2, or TiO2.

[0111] Optionally, the fluorescent layer includes:

[0112] First fluorescent layer;

[0113] The second fluorescent layer is disposed on the light-emitting side of the first fluorescent layer;

[0114] The luminescent material in the first fluorescent layer is different from the luminescent material in the second fluorescent layer. The luminescent material in the second fluorescent layer is KSF phosphor.

[0115] Optionally, the luminescent material of the first fluorescent layer includes: β-SiAlON phosphor, chlorosilicate phosphor, YAG phosphor, TAG phosphor, or Ca-α-SiAlON phosphor.

[0116] Optionally, the thickness of the first fluorescent layer is 150–200 μm;

[0117] The thickness of the second fluorescent layer is 80–100 μm.

[0118] Optionally, the LED packaging structure further includes a protective layer disposed around the blue LED chip.

[0119] Optionally, the thickness of the protective layer is 80–100 μm.

[0120] Optionally, refer to Figure 8 The backlight module 200 includes:

[0121] The back plate 210 is the basic support structure of the entire backlight module 200. It can be bent in an F-shape to form an accommodating space for installing other components in the backlight module 200. The back plate 210 can provide mechanical support and protect the internal components in the backlight module 200.

[0122] The LED beads 20, or the array of LED beads 20 described in the above embodiments, are disposed at the bottom of the accommodating space formed by the back plate 210 to provide the necessary light source for the backlight module 200.

[0123] The reflective film 220, located inside the back panel 210, is used to reflect light from inside the backlight module 200 back, thereby improving light utilization efficiency.

[0124] The diffuser plate 230 is located on the light-emitting side of the LED beads 20. Its function is to homogenize the light, making the light softer and more uniform, and reducing light spots and shadows.

[0125] Optical functional film 240 is located on the light-emitting side of the diffuser plate; the optical functional film may include: brightness enhancement film, prism sheet, etc., to enhance the brightness of light and improve the display effect.

[0126] The beneficial effects of the backlight module provided in this application embodiment are the same as those of the LED lamp beads provided in the above embodiments, and other technical features in the backlight module are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0127] A third aspect of this application provides a display device, which includes: LED beads as described above, or a backlight module as described above.

[0128] Optionally, the LED beads include:

[0129] Blue LED chips;

[0130] A fluorescent layer is disposed on the light-emitting side of the blue LED chip;

[0131] A diffusion layer is disposed on the light-emitting side of the fluorescent layer, and a recess is formed in the middle portion of the diffusion layer facing the light-incident side of the diffusion layer;

[0132] The support has a receiving groove, in which the blue LED chip and the phosphor layer are both disposed. The diffusion layer covers the opening of the receiving groove to form a sealed container.

[0133] Optionally, the recess depth of the diffusion layer is 30–50 μm, and the edge thickness of the diffusion layer is 80–100 μm.

[0134] Optionally, the diffusion layer contains diffusion particles, including PET, PMMA, PP, PS, MS, SiO2, or TiO2.

[0135] Optionally, the fluorescent layer includes:

[0136] First fluorescent layer;

[0137] The second fluorescent layer is disposed on the light-emitting side of the first fluorescent layer;

[0138] The luminescent material in the first fluorescent layer is different from the luminescent material in the second fluorescent layer. The luminescent material in the second fluorescent layer is KSF phosphor.

[0139] Optionally, the luminescent material of the first fluorescent layer includes: β-SiAlON phosphor, chlorosilicate phosphor, YAG phosphor, TAG phosphor, or Ca-α-SiAlON phosphor.

[0140] Optionally, the thickness of the first fluorescent layer is 150–200 μm;

[0141] The thickness of the second fluorescent layer is 80–100 μm.

[0142] Optionally, the LED packaging structure further includes a protective layer disposed around the blue LED chip.

[0143] Optionally, the thickness of the protective layer is 80–100 μm.

[0144] Optionally, refer to Figure 9 The display device 400 includes: a backlight module 200 and a display panel 300;

[0145] The backlight module includes: a back plate 210, which is the basic support structure of the entire backlight module 200. It can be bent in an F-shape to form an accommodating space for installing other components within the backlight module 200. The back plate 210 provides mechanical support and protects the internal components of the backlight module 200. The LED beads 20, or an array of LED beads 20, described in the above embodiment, are positioned at the bottom of the accommodating space formed by the back plate 210, providing the necessary light source for the backlight module 200. A reflective film 220, located inside the back plate 210, reflects light from inside the backlight module 200 back, improving light utilization efficiency. A diffuser plate 230, located on the light-emitting side of the LED beads 20, homogenizes the light, making it softer and more uniform, reducing light spots and shadows. An optical functional film 240, located on the light-emitting side of the diffuser plate, may include a brightness enhancement film, a prism sheet, etc., to enhance light brightness and improve display effects.

[0146] The display panel 300 is located on the light-emitting side of the optical functional film 240 in the backlight module 200. It is the final display part of the display device and is used to display images and text.

[0147] The beneficial effects of the display device provided in this application embodiment are the same as those of the LED lamp beads provided in the above embodiments, and other technical features in the display device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0148] In order to enable those skilled in the art to clearly understand the details and operations of the above embodiments of this application, and to demonstrate the significant improvement in performance of the embodiments of this application, the above technical solutions are illustrated below through multiple embodiments.

[0149] Example 1

[0150] The LED chip includes: a blue LED chip; a 90µm silicone protective layer; a 150µm first phosphor layer with β-SiAlON phosphor as the luminescent material; and an 80µm second phosphor layer with KSF phosphor as the luminescent material.

[0151] Example 2

[0152] The LED chip includes: a blue LED chip; a 90µm silicone protective layer; a 200µm first phosphor layer with β-SiAlON phosphor as the luminescent material; and an 80µm second phosphor layer with KSF phosphor as the luminescent material.

[0153] Example 3

[0154] The LED chip includes: a blue LED chip; a 90µm silicone protective layer; a 200µm first phosphor layer with β-SiAlON phosphor as the luminescent material; and an 80µm second phosphor layer with KSF phosphor as the luminescent material, the surface of which is covered with a 30nm BaF2 inorganic passivation layer.

[0155] Example 4

[0156] The LED chip includes: a blue LED chip; a 90µm silicone protective layer; a 200µm first phosphor layer with β-SiAlON phosphor as the luminescent material; and an 80µm second phosphor layer with KSF phosphor as the luminescent material, the surface of which is provided with a 50nm BaF2 inorganic passivation layer.

[0157] Comparative Example 1

[0158] The LED chip includes: a blue LED chip; a 90µm silicone protective layer; and a 280µm mixed phosphor layer. The luminescent materials include β-SiAlON phosphor and KSF phosphor.

[0159] Comparative Example 2

[0160] The LED chip includes: a blue LED chip; a 90µm silicone protective layer; and a 280µm mixed phosphor layer. The luminescent materials include β-SiAlON phosphor and KSF phosphor, with a 50nm BaF2 inorganic passivation layer on the surface of the KSF phosphor.

[0161] The above-mentioned examples and comparative examples were tested using the industry testing standard of 85℃ / 85%RH / 1000H. The experimental results are shown in Table 1 below, where △L is the brightness attenuation, △x is the change in color coordinate x, and △y is the change in color coordinate y.

[0162] Table 1:

[0163]

[0164]

[0165] Based on the experimental results above, it can be seen that in Comparative Examples 1 and 2, the direct contact between the mixed phosphor layer and the blue LED chip generates blue light interference, and the relatively large driving current of 700mA produces high heat, leading to thermal decay and light attenuation of the KSF phosphor, resulting in decreased brightness and color coordinate drift. In contrast, the vertical multilayer structure of this embodiment reduces the heat and blue light intensity transmitted to the KSF phosphor in the second phosphor layer, thus avoiding thermal decay and light attenuation of the KSF phosphor. This results in lower brightness decay of the LED chip and better color consistency. Furthermore, by setting an inorganic passivation layer on the luminescent material, the excitation efficiency of the KSF phosphor can be further improved.

[0166] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the patent protection scope of this application.

Claims

1. An LED lamp bead, characterized in that, The LED beads include: Blue LED chips; A fluorescent layer is disposed on the light-emitting side of the blue LED chip; A diffusion layer is disposed on the light-emitting side of the fluorescent layer, and a recess is formed in the middle portion of the diffusion layer facing the light-incident side of the diffusion layer; The support has a receiving groove, in which the blue LED chip and the phosphor layer are both disposed. The diffusion layer covers the opening of the receiving groove to form a sealed container.

2. The LED lamp bead as described in claim 1, characterized in that, The recess depth of the diffusion layer is 30~50 μm, and the edge thickness of the diffusion layer is 80~100 μm.

3. The LED lamp bead as described in claim 1, characterized in that, The fluorescent layer includes: First fluorescent layer; The second fluorescent layer is disposed on the light-emitting side of the first fluorescent layer; The luminescent material in the first fluorescent layer is different from the luminescent material in the second fluorescent layer. The luminescent material in the second fluorescent layer is KSF phosphor.

4. The LED lamp bead as described in claim 3, characterized in that, The thickness of the first fluorescent layer is 150~200 μm; The thickness of the second fluorescent layer is 80~100 μm.

5. The LED lamp bead as described in any one of claims 1 to 4, characterized in that, The LED packaging structure further includes a protective layer disposed around the blue LED chip.

6. The LED lamp bead as described in claim 5, characterized in that, The thickness of the protective layer is 80~100 μm.

7. A backlight module, characterized in that, The backlight module includes LED beads as described in any one of claims 1 to 6.

8. A display device, characterized in that, The display device includes LED beads as described in any one of claims 1 to 6, or a backlight module as described in claim 7.

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