LED植物灯高均匀性照明鳞甲透镜设计

Design of High Uniformity Illumination Scale Lens for Light-Emitting Diode Plant Lamp

针对现有植物灯照度均匀性不高和效率低下的问题,本团队设计了一种LED鳞甲透镜植物灯。首先研究了红光和蓝光LED的配比和排列方法,采用9点法进行光谱测量,研究了光谱分布的均匀性;然后根据光学原理和非成像光学原理设计了一款鳞甲透镜,利用鳞甲透镜的鳞甲弧度将LED发出的光线均匀化,增加光线的耦合程度,进而提高出光面的光学效率和均匀性;最后将14颗1 W三星3535蓝光LED灯珠(型号为LH351H 450 nm L4A4B)和70颗1.6 W三星3535红光LED灯珠(型号为LH351H 660 nm V2 E7W410)作为植物灯光源,在尺寸为380 mm×220 mm的植物灯中均分为7行,每行12颗LED,通过TracePro软件进行仿真实验。仿真结果表明,当红光与蓝光光子数比8∶1时,红光LED和蓝光LED均匀排列方式的光谱均匀性优于蓝光LED均分两列排列方式的光谱均匀性。最后制作LED植物灯,整灯测试结果表明,当鳞甲透镜长为22 mm,宽度为16 mm,最大高度为6.68 mm,内表面的底面直径为6.26 mm,内表面高为2.98 mm,鳞甲凸起高度为0.1 mm,鳞甲宽度为0.35 mm,两个LED中心列间距为25 mm时,植物灯的光束角为90°,接收面距植物灯出光面0.5 m,在500 mm×500 mm的照明区域上可以得到光量子通量密度(PPFD)均匀性为93.12%、光学效率为90%的植物照明面光源。

Objective Currently, the approaches to achieving uniform illumination largely involve adjusting the array arrangement of light-emitting diode(LED) plant light sources, designing the structure of an LED light source board, and adding optical features such as diffusion plate or free-form surface baseplate. These approaches cannot effectively enhance the uniform illumination of LED plant light because the optical efficiency is not high, and it is not conducive to large-area lighting of LED plant lamps. The red and blue LED array light sources widely used in plant manufacturing have been tuned to provide spectral uniformity based on the aforementioned issues. The scale lens is then designed, and the light output by the LED is uniform by employing the scale radian of the scale lens, which improves the optical efficiency and uniformity of the light surface by increasing the light coupling degree. It has some practical utility and serves as a guide for consistent illumination of large-area plants in practical engineering.Methods First, 14 pieces of 1 W Samsung 3535, type LH351H 450 nm L4A4B blue LEDs and 70 pieces of 1.6 W Samsung 3535, type LH351H 660 nm V2 E7W410 red LEDs were used as plant lamp light sources, divided into seven rows with 12 LEDs in each row with a size of 380 mm×220 mm of LED plant lamp;the ratio and way of arrangement of the red and blue LEDs were studied. After comparing the spectra of two distinct LED array arrangement methods, the nine-point method was used to measure the spectrum. Second, a scale lens was designed according to optical and nonimaging optical principles. The scale radian of the scale lens ensures that the light output by the LED is uniform. Then, to find the best scale lens size, the impacts of different bulge heights, scales width, and the spacing between two LEDs center columns on photosynthetic photon flux density(PPFD) uniformity and optical efficiency were analyzed. Finally, the results were verified by experiment.Results and Discussions It is the first time that a scale lens has been applied to an LED plant lamp to improve the illumination spectral uniformity and optical efficiency of the LED plant lamp. The homogeneous arrangement of red and blue LEDs was used to evaluate the LED plant light source. The experimental spectrum with uniform arrangement of red and blue LEDs in the LED plant light is essentially consistent with the theoretical simulation spectrum, and the spectral uniformity is good(Fig. 17). The scale lens was designed according to optical and nonimaging optical principles. By comparing the effects of the width and convex height of the scale lens on the PPFD uniformity and optical efficiency of the plant lamp, the optimized convex height H of the scale lens is 0.1 mm, the optimized scale width D is 0.35 mm, the optimized center column spacing B between two LEDs is 25 mm, the ray-tracing simulation with the Trace Por software revealed that the light distribution curve of the whole LED plant lamp exhibits batwing light distribution. The experiment and simulation were well-accorded(Fig. 19). The test results show that the scale lens module has a PPFD uniformity of 93.12% in the illumination area within 500 mm×500 mm(Fig. 20), and optical efficiency of 90%, which is higher than the technical indexes reported in the references, thereby demonstrating the effectiveness of the scale lens.Conclusions The software simulation demonstrates that when the photon number ratio of red light to blue light is 8∶1, and 14 pieces of 1 W Samsung 3535, type LH351H 450 nm L4A4B blue LEDs, and 70 pieces of 1.6 W Samsung 3535, type LH351H 660 nm V2 E7W410 red LEDs are divided into seven rows with twelve LEDs in each row with a size of 380 mm×220 mm of LED plant lamp, the spectral uniformity of uniform arrangement of red LED and blue LED is better than that of uniform arrangement of blue LED in two columns. The experimental findings reveal that when the length of the scale lens is 22 mm, the width is 16 mm, the maximum height is 6.68 mm, the diameter of the bottom surface of the inner surface is 6.26 mm, the height is 2.98 mm, the height of the scale protrusion is 0.1 mm, the width of the scale is 0.35 mm, and the distance between the center columns of the two LEDs is 25 mm, the beam angle of the plant lamp is 90°, the receiving surface is 0.5 m away from the light-emitting surface of the plant lamp, and the 500 mm×500 mm plant illumination surface light source with PPFD uniformity of 93.12% and optical efficiency of 90% is obtained in the illumination area.