Small-angle LED lamp bead with built-in uniform light microstructure and preparation method thereof

Abstract

The application discloses a small-angle LED lamp bead with built-in uniform light microstructure and a preparation method thereof. The small-angle LED lamp bead comprises a multilayer encapsulation body, the multilayer encapsulation body covers an LED chip, and comprises a first encapsulation layer and a second encapsulation layer. The first encapsulation layer contains fluorescent powder and directly covers the LED chip. The second encapsulation layer is arranged on a first upper surface of the first encapsulation layer. The second encapsulation layer is composed of transparent encapsulation glue and has a second upper surface with a convex lens topography facing a light-emitting direction. First micro-scattering particles are doped in the transparent encapsulation glue of the second encapsulation layer. In the application, the second encapsulation layer can converge light to form a collimated small-angle light beam. The first micro-scattering particles doped in the second encapsulation layer can accurately scatter the residual blue light with strong directivity in the center region of the light beam to the surrounding through Mie scattering, so that the blue light is finally finely mixed with the surrounding yellow light, and the light-emitting uniformity is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LED lamp beads, in particular to a small-angle LED lamp bead with built-in light-uniformizing microstructure and a preparation method thereof. BACKGROUND

[0002] Small-angle white light LED lamp beads have a wide range of applications in the fields of stage lighting, automobile headlamps, special lighting, etc. due to their concentrated light and long irradiation distance. At present, small-angle light emission is usually achieved by adding an extra lens outside the LED chip package or by using a simple spherical or aspherical lens structure inside the package.

[0003] However, the existing technical solutions generally have the following defects:

[0004] Non-uniform color of light spot: the light path and distribution of blue light and yellow light inside the white light formed by exciting yellow phosphor with a blue LED chip are difficult to be completely consistent. After collimation by the lens, the central region of the light spot is prone to have blue light that is not fully mixed, i.e., the "central blue leakage" phenomenon; while the edge region of the light spot is prone to have excessive yellow light, forming a "yellow circle" or "yellow spot".

[0005] Low energy utilization rate: the simple package structure cannot effectively handle the light emitted laterally and at large angles by the chip, and this part of energy is often absorbed by the support or forms stray light, resulting in low overall light efficiency.

[0006] Conflict between structure and performance: some complex structures designed to improve optical performance, such as embedding multiple preformed optical components inside the package, will result in extremely complex production processes, high costs, and low yield, which are not suitable for large-scale production.

[0007] Therefore, there is an urgent need for a new type of LED lamp bead technical solution that can integrally solve the two major problems of small-angle collimation and high-uniformity mixing light at the package level, and has a relatively simple process and controllable cost. SUMMARY

[0008] To solve the technical problems in the prior art, the present application provides a small-angle LED lamp bead with built-in light-uniformizing microstructure and a preparation method thereof.

[0009] The small-angle LED lamp bead with built-in light-uniformizing microstructure and the preparation method thereof provided by the present application adopt the following technical solution:

[0010] The small-angle LED lamp bead with built-in light-uniformizing microstructure and the preparation method thereof comprise an LED support and an LED chip arranged in the LED support, and further comprise a multilayer package covering the LED chip and comprising:

[0011] a first encapsulation layer comprising phosphor and directly covering the LED chip, the first encapsulation layer having a concave lens topography or a planar first upper surface facing the light emitting direction;

[0012] a second encapsulation layer disposed on the first upper surface of the first encapsulation layer, the second encapsulation layer being composed of transparent encapsulation glue and having a convex lens topography of the second upper surface facing the light emitting direction;

[0013] and the transparent encapsulation glue of the second encapsulation layer is doped with first micro-scattering particles.

[0014] In some embodiments, the first micro-scattering particles have a particle size of 200-600 nm and a concentration of less than 0.1 wt%.

[0015] In some embodiments, the LED support is a bowl-shaped structure, and the inner wall of the bowl-shaped structure is provided with a dichroic filter film which is highly reflective to blue light and partially absorbs or transmits yellow light.

[0016] The dichroic filter film comprises a high refractive index layer and a low refractive index layer, the refractive index of the high refractive index layer being higher than that of the low refractive index layer, and the optical thickness of the high refractive index layer and the low refractive index layer being equal to one quarter of the central wavelength of blue light.

[0017] In some embodiments, the multilayer encapsulation body further comprises a third encapsulation layer, the third encapsulation layer being filled between the sidewalls of the first encapsulation layer and the second encapsulation layer and the inner wall of the LED support, the third encapsulation layer being composed of white encapsulation glue containing second micro-scattering particles.

[0018] In some embodiments, the material of the first micro-scattering particles and the second micro-scattering particles is one or more of silicon dioxide, aluminum trioxide or titanium dioxide.

[0019] In some embodiments, the particle size of the second micro-scattering particles is 0.5-5 µm.

[0020] In some embodiments, when the first encapsulation layer has a concave lens topography facing the light emitting direction, the geometric and optical parameters of the first encapsulation layer and the second encapsulation layer are matched so that the final virtual image formed after the action of the first encapsulation layer falls exactly on the front side focal point of the second encapsulation layer, so that the final emitted light is a collimated light beam.

[0021] In some embodiments, the small-angle LED lamp bead with built-in light homogenization microstructure further comprises a lens layer which is covered on the second encapsulation layer and is composed of transparent material.

[0022] In some embodiments, a plurality of light-reflecting inclined grooves are further arranged on the inner wall of the LED support along the depth direction thereof.

[0023] The application further provides a preparation method of the small-angle LED lamp bead with built-in light-uniformizing microstructure.

[0024] S1, providing an LED support provided with an LED chip;

[0025] S2, forming a first encapsulating layer containing fluorescent powder above the LED chip by a dispensing or molding process, and curing the first encapsulating layer to have a concave lens topography or a first upper surface being flat;

[0026] S3, forming a second encapsulating layer doped with first micro-scattering particles on the first upper surface of the first encapsulating layer by a dispensing or molding process, and curing the second encapsulating layer to have a convex lens topography of a second upper surface.

[0027] To sum up, the application has at least one of the following beneficial technical effects:

[0028] 1. The unique concave lens topography of the first encapsulating layer plays a role of a diverging lens, and can preliminarily expand and mix the blue light emitted by the chip and the yellow light excited by the fluorescent powder in the initial stage of the light path, avoiding chroma concentration; the second encapsulating layer can converge light to form a collimated small-angle light beam, and the first micro-scattering particles with a particle size of 200-600 nm doped in the second encapsulating layer can accurately scatter the residual blue light with strong directivity in the center of the light beam to the surrounding through Mie scattering, so as to realize the final fine mixing of the blue light and the yellow light around; the dichroic filter film on the inner wall of the LED support is designed as a "quarter-wave film stack" that "reflects blue light and transmits yellow light", which can intelligently reflect the lateral blue light back to the central light mixing area while allowing the yellow light to pass through, thereby assisting color mixing from the aspect of light path regulation and further improving uniformity.

[0029] 2. The third encapsulating layer is composed of white encapsulating glue containing a high concentration of second micro-scattering particles, which can efficiently diffuse and reflect the light emitted from the side of the chip back to the central light path, realizing energy recycling and reuse; the light-reflecting inclined grooves arranged on the inner wall of the LED support have an optimized inclination angle, which can more effectively reflect the large-angle outgoing light that may otherwise be absorbed or form stray light to the desired outgoing direction. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a structural schematic diagram of the small-angle LED lamp bead with built-in light-uniformizing microstructure provided by Embodiment 1 of the application;

[0031] Figure 2 isFigure 1 a process schematic diagram of the preparation method of the small-angle LED lamp bead in

[0032] Figure 3 is a structural schematic diagram of the small-angle LED lamp bead with built-in light-uniformizing microstructure provided by Embodiment 2 of the present application;

[0033] Figure 4 is Figure 3 a process schematic diagram of the preparation method of the small-angle LED lamp bead in

[0034] Figure 5 is a structural schematic diagram of the small-angle LED lamp bead with built-in light-uniformizing microstructure provided by Embodiment 3 of the present application;

[0035] Label explanation: 1, LED support; 2, LED chip; 3, first encapsulation layer; 4, second encapsulation layer; 5, third encapsulation layer; 6, lens layer; 7, transparent cover. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be further described in detail below with reference to the drawings. The described embodiments are only possible technical implementations of the present application, but are not limited thereto, and those skilled in the art can certainly combine the embodiments of the present application without creative labor to obtain other embodiments within the protection scope of the present application.

[0037] The present application mainly uses a multi-layer encapsulation body combined with micro-scattering particles to achieve small-angle high-uniformity light emission, so as to improve the light spot uniformity, collimation effect and energy utilization rate, and facilitate production. The present application will be described in further detail below.

[0038] Embodiment 1

[0039] Please refer to Figure 1 and Figure 2 The small-angle LED lamp bead with built-in light-uniformizing microstructure provided by the embodiments of the present application includes an LED support 1, an LED chip 2 and a multi-layer encapsulation body. The multi-layer encapsulation body covers the LED chip 2 and can homogenize and collimate light, thereby improving the light spot uniformity and collimation effect. This is because the special structure and material of each layer of the multi-layer encapsulation body can effectively process light, so that the light is uniformly mixed and emitted in a small-angle direction.

[0040] Specifically, the LED support 1 is a bowl-shaped structure, which supports and accommodates other components. The inner wall of the LED support 1 is provided with a plurality of light reflection inclined grooves along the depth direction thereof, and the inclined angle of the light reflection inclined grooves is optimized, so that the light rays with large angles can be more effectively reflected to the light emission direction. In addition, the inner wall of the LED support 1 is further provided with a dichroic filter film which has high reflectivity to blue light and partially absorbs or transmits yellow light. The dichroic filter film includes a high-refractive layer and a low-refractive layer. The refractive index of the high-refractive layer is higher than that of the low-refractive layer, and the optical thicknesses of the high-refractive layer and the low-refractive layer are equal to one fourth of the central wavelength of the blue light. Such a structure can better control the propagation of blue light and yellow light, and reduce unnecessary light loss.

[0041] In the embodiment, the dichroic filter film is based on the thin film interference principle, and the most basic and core design is the "quarter wavelength film stack" design.

[0042] The design requires that the "optical thickness" of each layer of film in the film stack is exactly equal to one fourth of the target reflection central wavelength (λ0). The optical thickness is equal to the product of the physical thickness (d) and the refractive index (n) of the material. Let the refractive indices of the high-refractive layer and the low-refractive layer be n1 and n2 respectively, and the physical thicknesses thereof be d1 and d2 respectively. d n n H and n L , the physical thicknesses thereof are d H and d L , they need to satisfy:

[0043]

[0044] To achieve "reflecting blue light and transmitting yellow light", the central wavelength of the blue light λ0 can be set to 460 nm. High-refractive materials such as titanium dioxide (TiO2, n H ≈2.4) and low-refractive materials such as silicon dioxide (SiO2, n L ≈1.46) are selected. According to the formula, the required thicknesses are calculated to be d H ≈47.9 nm and d L ≈78.8 nm. Through processes such as physical vapor deposition, the two materials are alternately deposited on the inner wall of the support with the calculated thicknesses to form a film stack structure. This structure can produce high-efficiency constructive interference for blue light around 460 nm to achieve high reflectivity, while yellow light with a longer wavelength can pass through smoothly, thereby achieving intelligent color light separation and regulation and assisting color mixing.

[0045] ​​Specifically, the LED chip 2 is arranged in the LED support 1 and is a light source of the whole lamp bead. When powered, the LED chip 2 emits blue light to provide a basis for subsequent white light generation.

[0046] Specifically, please refer to Figure 1 and Figure 2 The multi-layer package includes a first package layer 3 and a second package layer 4. The first package layer 3 contains phosphor and directly covers the LED chip 2, and the first package layer 3 has a first upper surface with a concave lens topography facing the light emitting direction. The first package layer 3 is composed of silica gel mixed with yellow phosphor, and the silica gel has good optical performance and stability. Through the molding or precise dispensing process, it is directly covered on the LED chip 2. When the blue light emitted by the chip excites the phosphor to emit light, the mixed light first passes through this concave surface. The concave surface plays the role of a diverging lens, which preliminarily expands and mixes the light, greatly improves the apparent uniformity of the light source, and avoids the formation of color concentration that is difficult to eliminate in the initial stage of the light path. The phosphor here can also be selected from other types of fluorescent materials as long as it can produce light of the appropriate color under blue light excitation.

[0047] Specifically, please refer to Figure 1 and Figure 2 The second package layer 4 is arranged on the first upper surface of the first package layer 3, and the second package layer 4 is composed of transparent encapsulating glue and has a second upper surface with a convex lens topography facing the light emitting direction. The transparent encapsulating glue of the second package layer 4 is doped with first micro-scattering particles, and the particle size of the first micro-scattering particles is between 200 nm and 600 nm, and the concentration is less than 0.1 wt%. The transparent encapsulating glue can be selected from materials such as epoxy resin with high light transmittance. The material of the first micro-scattering particles can be one or more of silicon dioxide, aluminum trioxide or titanium dioxide. When the light enters the second package layer 4, most of the light is converged by the convex lens of the second upper surface to form a collimated small-angle light beam. For the residual blue light in the center of the light beam, which is highly directional, they will collide with the internal first micro-scattering particles when passing through the second package layer 4, causing Mie scattering, and thus scattering uniformly to the surrounding, and finally achieving fine mixing with the surrounding yellow light.

[0048] In this embodiment, the first micro-scattering particles in the second encapsulation layer 4 have the core target of efficiently scattering the residual blue light (wavelength about 450 nm) while trying to avoid excessive impact on yellow light (wavelength about 560 nm) and reducing the backscattering of light (which will reduce the light efficiency). This requirement is most suitable for Mie Scattering. Mie Scattering occurs when the particle size is comparable to the wavelength of light. Therefore, the particle size of the micro-particles in the B layer is usually controlled between 200 nm and 600 nm. This size range can produce the most efficient scattering of blue light, disrupting its directionality, and thus mixing with yellow light, without causing light separation or excessive haze due to excessive particle size. At the same time, the concentration of the first micro-scattering particles must be very low. The purpose is only to "perturb" the light path, eliminate the central blue light component, and not make the entire lens hazy.

[0049] In this embodiment, the geometric and optical parameters of the first encapsulation layer 3 and the second encapsulation layer 4 are matched so that the final virtual image formed after the action of the first encapsulation layer 3 falls exactly on the front side focal point of the second encapsulation layer 4, so that the final outgoing light is a collimated light beam.

[0050] In this embodiment, to achieve collimated output, the parameters between the first encapsulation layer 3 and the second encapsulation layer 4 need to satisfy an exact matching relationship. This relationship is based on the principle of compound lenses: the chip virtual image formed by the first encapsulation layer 3 must be located on the front side focal point of the second encapsulation layer 4. Define d A ,R A ,n A For the central thickness, concave curvature radius and refractive index of the first encapsulation layer 3, d B ,R B ,n B For the corresponding parameters of the second encapsulation layer 4, they need to satisfy the following relationship:

[0051]

[0052] Through this formula, the design of the geometric and optical parameters of each layer can be guided to achieve the best optical performance.

[0053] Specifically, please refer to Figure 1 and Figure 2, the multilayer encapsulation body can further comprise a third encapsulation layer 5 filled between the sidewalls of the first and second encapsulation layers 3 and 4 and the inner wall of the LED support 1, the third encapsulation layer 5 being composed of white encapsulation glue containing second micro-scattering particles. The particle size of the second micro-scattering particles is between 0.5 - 5 µm, and the material can be one or more of silica, alumina or titanium dioxide. The white encapsulation glue can diffuse the light emitted from the chip side to return to the central light path, achieving energy recycling and reuse and improving overall light efficiency.

[0054] In this embodiment, the target of the second micro-scattering particles in the third encapsulation layer 5 is to maximize the diffuse reflection of light of all wavelengths (blue and yellow) back to the central light path to achieve light energy recycling. What it needs is a high-efficiency white reflector. To achieve the strongest diffuse reflection effect, larger and more widely distributed particles are usually used. The particle size of the second micro-scattering particles in the third encapsulation layer 5 is usually between 0.5 µm (500 nm) and 5 µm. Particles of this size (especially high-refractive-index TiO2) can produce strong scattering to the entire visible spectrum, thereby achieving extremely high reflectivity. At the same time, the concentration of the second micro-scattering particles can be higher to be maximally reflected.

[0055] Specifically, please refer to Figure 5 The built-in light-uniformizing microstructure small-angle LED lamp bead provided by the embodiment of the present application can further comprise a lens layer 6 covering the second encapsulation layer 4 and composed of transparent material, the lens layer 6 having a convex lens-shaped outer surface facing the light-emitting direction. The lens layer 6 mainly functions to protect the first, second and third encapsulation layers 3, 4 and 5.

[0056] The implementation principle of the embodiment is that through the unique structure and material design of each layer of the multilayer encapsulation body and the effect of the micro-scattering particles, efficient light uniformization and collimation are achieved. The concave structure of the first encapsulation layer 3 pre-diverges and mixes the light to improve light uniformity from the source; the convex lens structure and micro-scattering particles of the second encapsulation layer 4 further converge and finely mix the light and collimate the output; the third encapsulation layer 5 recycles the lateral light to improve energy utilization; and the lens layer 6 can protect the first, second and third encapsulation layers 3, 4 and 5. Compared with the prior art, the whole structure effectively solves the problems of non-uniformity of spot chroma and low energy utilization, and the process is relatively simple and suitable for large-scale production.

[0057] Embodiment 2

[0058] Please refer to Figure 3 and Figure 4The difference between the embodiment and the above-mentioned embodiments is that the first encapsulation layer 3 has a first upper surface which is flat towards the light emitting direction. Although there is no pre-dispersion effect of the concave lens topography, the micro-scattering particles in the subsequent second encapsulation layer 4 can still homogenize the light to a certain extent. The second encapsulation layer 4 and other structures are the same as those in Embodiment 1, and the light can still be collimated and further mixed by the convex lens structure and micro-scattering particles, and the third encapsulation layer 5 and the lens layer 6 can also play a corresponding energy recovery and collimation optimization role.

[0059] The implementation principle of the embodiment is that although the first encapsulation layer 3 has no pre-dispersion function of the concave lens topography, the overall structure can still realize small-angle light emission and a certain degree of light homogenization effect through the synergistic effect of each layer. Compared with the prior art, the micro-scattering particles and convex lens structure of the second encapsulation layer 4 can effectively improve the light spot uniformity and collimation effect, the third encapsulation layer 5 and the lens layer 6 also help to improve the energy utilization rate and collimation accuracy, and the process is relatively simple, thereby reducing the production cost.

[0060] Embodiment 3

[0061] The difference between Embodiment 3 and Embodiment 1 is that in Embodiment 3, the lens layer 6 is not included, but a transparent cover 7 is used to replace the lens layer 6, the transparent cover 7 has a uniform thickness and covers the first encapsulation layer 3, the second encapsulation layer 4 and the third encapsulation layer 5, thereby achieving a protection effect.

[0062] Embodiment 4

[0063] The preparation method of the small-angle LED lamp bead with built-in light homogenization microstructure provided by the embodiment of the application comprises the following steps:

[0064] S1, providing an LED support 1 provided with an LED chip 2. This step needs to prepare a suitable LED support 1 and an LED chip 2, and the bowl-shaped structure and the high-reflection coating, the light reflection chute, the dichroic filter film and other structures of the inner wall of the LED support 1 need to meet the design requirements. The LED support 1 that meets the specifications can be purchased, and then the LED chip 2 is accurately installed in the support. The installation process needs to ensure that the position of the chip is accurate and the electrical connection is good.

[0065] S2, forming a first encapsulation layer 3 containing fluorescent powder above the LED chip 2 by means of dispensing or molding process, and making it solidify into a first upper surface with a concave lens topography or a flat surface. If the dispensing process is used, a precise dispensing device needs to be used to accurately point and coat the silicone mixed with fluorescent powder on the LED chip 2, and then it is solidified by heating or ultraviolet irradiation. The molding process needs to use a special mold to put the silicone material into the mold, and apply a certain pressure and temperature to make it form and solidify. In this process, the concentration and distribution of the fluorescent powder and the shape of the first upper surface need to be controlled.

[0066] S3, on the first upper surface of the first encapsulation layer 3, a second encapsulation layer 4 doped with first micro-scattering particles is formed by a dispensing or molding process, and is cured to have a second upper surface with a convex lens topography. Similarly, the dispensing or molding process can be selected according to the actual situation. When forming the second encapsulation layer 4, it is ensured that the first micro-scattering particles are uniformly dispersed in the transparent encapsulation glue, and the convex lens shape and parameters of the second upper surface are controlled.

[0067] S4, filling a third encapsulation layer 5 between the sidewalls of the first encapsulation layer 3 and the second encapsulation layer 4 and the inner wall of the LED support 1;

[0068] S5, using a similar dispensing or molding process to prepare a third lens layer 6 on the second encapsulation layer 4 and the third encapsulation layer 5.

[0069] The implementation principle of the embodiment is that through orderly steps, using mature processes such as dispensing or molding, each component and encapsulation layer is prepared in turn to form a complete small-angle LED lamp bead with built-in uniform light microstructure. Compared with the prior art, this preparation method does not need a complex assembly process, can integrally solve the problems of small-angle collimation and high uniformity of mixed light at the encapsulation layer level, improves production efficiency, reduces production cost, and is suitable for large-scale production.

[0070] The technical effects of the technical solutions provided in the application include:

[0071] (1) The unique concave lens topography of the first encapsulation layer 3 plays the role of a diverging lens, which can preliminarily expand and mix the blue light emitted by the chip and the yellow light excited by the phosphor at the initial stage of the light path, avoiding chroma concentration; the second encapsulation layer 4 can converge light to form a collimated small-angle light beam, and the first micro-scattering particles with a particle size of 200-600 nm doped in the second encapsulation layer 4 can accurately scatter the residual blue light in the center of the light beam through Mie scattering, so that the blue light is scattered to the surrounding yellow light to achieve the final fine mixing; the dichroic filter film on the inner wall of the LED support 1 is designed as a "quarter-wave film stack" that "reflects blue light and transmits yellow light", which can intelligently reflect the lateral blue light back to the center mixing area while allowing yellow light to pass through, assisting color mixing from the aspect of light path regulation, and further improving uniformity;

[0072] (2) The third encapsulation layer 5 is composed of white encapsulation glue containing a high concentration of second micro-scattering particles, which can efficiently diffuse the light emitted laterally from the chip back to the center light path, realizing energy recycling and reuse; the reflective inclined groove provided on the inner wall of the LED support 1 has an optimized inclination angle, which can more effectively reflect the large-angle outgoing light that may otherwise be absorbed or form stray light to the desired outgoing direction.

[0073] The specific embodiments of the present application described above are not meant to be limiting. Any other changes and modifications that one can make to the present application according to the technical concept thereof should be included within the scope of the present application.

Claims

1. A small-angle LED bead with a built-in uniform light microstructure, comprising an LED bracket (1) and an LED chip (2) disposed within the LED bracket (1), characterized in that, It also includes a multilayer package covering the LED chip (2) and comprising: The first encapsulation layer (3) contains phosphor and directly covers the LED chip (2). The first encapsulation layer (3) has a first upper surface with a concave lens shape facing the light emission direction. The second encapsulation layer (4) is disposed on the first upper surface of the first encapsulation layer (3). The second encapsulation layer (4) is made of transparent encapsulating adhesive and has a second upper surface with a convex lens shape facing the light emission direction. Furthermore, the transparent encapsulating adhesive of the second encapsulation layer (4) contains first micro-scattering particles; The LED bracket (1) is a bowl-shaped structure, and its inner wall is provided with a dichroic filter film that highly reflects blue light and partially absorbs or transmits yellow light. The dichroic filter film includes a high refractive index layer and a low refractive index layer. The refractive index of the high refractive index layer is higher than that of the low refractive index layer, and the optical thickness of the high refractive index layer and the low refractive index layer is equal to one-quarter of the center wavelength of blue light. The multilayer package further includes a third encapsulation layer (5), which is filled between the sidewalls of the first encapsulation layer (3) and the second encapsulation layer (4) and the inner wall of the LED bracket (1). The third encapsulation layer (5) is composed of white encapsulating adhesive containing second micro-scattering particles. When the first encapsulation layer (3) has a concave lens shape facing the light-emitting direction, the geometric and optical parameters of the first encapsulation layer (3) and the second encapsulation layer (4) are matched, so that the final virtual image formed by the action of the first encapsulation layer (3) falls precisely on the front focal point of the second encapsulation layer (4), thereby making the final emitted light a collimated beam.

2. The small-angle LED bead with built-in uniform light microstructure according to claim 1, characterized in that, The particle size of the first microscattering particles is between 200 nm and 600 nm, and the concentration is less than 0.1 wt%.

3. The small-angle LED bead with built-in uniform light microstructure according to claim 1, characterized in that, The materials of the first micro-scattering particles and the second micro-scattering particles are one or more of silicon dioxide, aluminum oxide, or titanium dioxide.

4. The small-angle LED bead with built-in uniform light microstructure according to claim 1, characterized in that, The particle size of the second microscattering particles is between 0.5 and 5 µm.

5. The small-angle LED bead with built-in uniform light microstructure according to claim 1, characterized in that, It also includes a lens layer (6) that covers the second encapsulation layer (4) and is made of a transparent material.

6. The small-angle LED bead with built-in uniform light microstructure according to claim 1, characterized in that, Multiple reflective grooves are also provided on the inner wall of the LED bracket (1) along the depth direction of the LED bracket (1).

7. A method for fabricating a small-angle LED bead with a built-in uniform light microstructure, characterized in that, The method for preparing small-angle LED beads with built-in uniform light microstructure as described in any one of claims 1-6 includes the following steps: S1. Provide an LED bracket (1) with an LED chip (2) installed; S2. A first encapsulation layer (3) containing phosphor is formed on top of the LED chip (2) by dispensing or molding process, and the first encapsulation layer (3) is cured into a first upper surface with a concave lens morphology. S3. On the first upper surface of the first encapsulation layer (3), a second encapsulation layer (4) doped with first micro-scattering particles is formed by dispensing or molding process, and the second encapsulation layer (4) is cured into a second upper surface with a convex lens morphology.

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