Optical simulation design of SMD beads for wide beam and high uniformity display
doi: 10.37188/CO.EN-2023-0017
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摘要:
本研究分析了目前用于显示器的高均匀宽角度灯珠的光学要求。采用新型非朗伯(non-Lambertian)分布封装Micro-LED芯片,实现了宽光束、高均匀性的微型LED芯片光珠。本文分析了在不同封装倾角、封装高度、封装材料、封装支架材料、蓝宝石厚度和图案化蓝宝石衬底尺寸下,使用由不同封装材料(铜、钛、铝和银)和材料类型(完全反射和完全吸收)组成的支架,模拟了固定灯珠的光输出效率和出光角度的变化。通过调整材料、芯片和封装参数,本文看可以得到一个、两个或三个光束,具有贴片灯珠的宽角度、高均匀性的远场光分布特性,可以满足当前LED和LCD的显示要求。
Abstract:This study analyses the optical requirements of wide beam and high uniformity light beads, which are currently used in displays. Packaging micro light-emitting diode (LED) chips with a novel non-Lambertian distribution has facilitated the production of micro-LED chip light beads that are wide in beam and high in uniformity. The light output efficiency and beam angle of fixed beads were simulated using brackets made of copper, titanium, aluminium and silver, as well as materials that were completely reflecting and absorbing. The simulations were conducted at various fixture angles, packaging heights, sapphire thicknesses, and patterned sapphire substrate sizes. By adjusting the chip and packaging parameters, we can obtain one, two, or three light beams with SMD lamp beads characteristics that provide wide angles, high uniformity, and far-field light distribution. These characteristics can meet the current display requirements for LED and LCD.
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Key words:
- non-lambertian distribution /
- lambertian distribution /
- displays /
- SMD lamp beads
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Table 1. Simulated optical parameters of different bracket materials
Material Refractive index Absorption Index [mm−1] Cu 1.15 65889 Al 0.7278 152263 Ag 0.886 113067 Ti 1.71 62667 Perfect absorption - 1 Perfect reflection 1 - Table 2. Simulated optical parameters of different packaging materials
Material Refractive index Absorption index [mm−1] Epoxy 2.605 0.0078 PMMA 1.499 0 Silica 1.41 0.01 Table 3. Simulated optical parameters of light-emitting diodes with different sizes
Material Thickness Refractive
indexAbsorption index
[mm−1]Sapphire 30 µm 1.70 0.004 ITO 300 nm 1.50 0 p-GaN 150 nm 2.45 2.300 Active layer (MQW) 100 nm 2.54 25 n-GaN 6.75 µm 2.45 2.3 Table 4. Simulated optical parameters of light-emitting diodes with different sizes
Width of
square [mm]Light-beam
angleLight extraction
efficiencyNumber of
light beams5 70 * 2 0.288 2 15 50 * 2 0.400 2 25 70 * 2 0.489 2 35 70 * 2 0.505 2 45 160 0.508 1 55 140 0.652 1 65 120 0.654 1 75 50 * 2 0.645 2 85 30 * 2 0.454 2 Table 5. Far-field beam angle and output efficiency of 5050 SMT beads with Al bracket and PMMA packaging materials at different angles Table 5. Far-field beam angles and output efficiencies of 5050 SMT beads with different packaging heights and Al brackets and PMMA packaging material at an inclination of 85°
Width of
square [mm]Light beam angle
without reflectionLight extraction efficiency Number of light beams 0.01 160 0.369 1 0.02 140 0.477 1 0.04 140 0.570 1 0.06 120 0.612 1 0.08 120 0.638 1 Table 6. Far-field beam angles and output efficiencies of 5050 SMT beads with different packaging materials, and a packaging height of 0.08 mmm, Al brackets at an inclination of 85°.
Material Light beam angle without reflection Light extraction efficiency Number of light beams Cu 140 0.247 1 Al 20 * 2 0.574 2 Ag 20 * 2 0.615 2 Ti 160 0.194 1 Perfect absorption 120 0.175 1 Perfect reflection 30 * 2 0.813 2 Table 7. Far-field beam angles and output efficiencies of 5050 SMT beads with different materials, a packaging height of 0.08 mm, and a sapphire thickness of 0.05 mm packaged with silicone supports at an inclination of 85°.
Width of square [mm] Light beam angle without reflection Light extraction efficiency Number of light beams Epoxy 30 * 2 0.511 2 PMMA 30 * 2 0.555 2 Silica 20 * 2 0.574 2 Table 8. Beam angles and output efficiencies of 5050 SMT beads with different chip sizes and Al brackets and PMMA packaging materials at an inclination of 85°
Cell size Light beam angle without reflection Light extraction efficiency Number of light beams 30 0.521 30*2 2 40 0.505 30*2 2 50 0.490 30*2 2 100 0.456 30*2 2 Table 9. Beam angles and output efficiencies of 5050 SMT beads with a sapphire thickness of 30 μm, Al brackets, and PMMA packaging materials at an inclination angle of 85°
Diameter of sapphire square structure Angle of light beam without reflection Light extraction efficiency Number of light beams 2 0.555 30 * 2 2 3 0.554 30 * 2 2 4 0.553 30 * 2 2 Table 10. Beam angles and output efficiencies of 5050 SMT beads with different sapphire thicknesses and Al brackets and PMMA packaging materials at an inclination angle of 85°
Sapphire length Light beam angle without reflection Light extraction efficiency Number of light beams 10 0.547 30*2 2 30 0.553 30*2 2 50 0.553 30*2 2 -
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