Direct-down LED panel light design for uniform illumination

According to the problems of high price of the ultra-thin LED panel light, high thickness and large quantity of LED for traditional direct-down LED panel light, a new direct-down LED panel light source is designed. The light source and target plane are meshed to form the mapping relationship based on the edge-ray theory. The differential equation of inner and outer freeform-surface is deduced on the basis of Snell formula, and the corresponding data of freeform-surface are calculated by using the iteration method. The secondary optical lens with large view angle for the new direct-down LED panel light is designed. Researches show that the double freeform-surface lens with large view angle can realize large angle light distribution with 150°, the illumination uniformity is 0.86, and the energy utilization is 99.5%. When the distanc e-height ratio (D/H) of LED array for the secondary optical lens with large view angle is approximately equal to 3, the illumination uniformity of the target surface is above 0.88 under different thicknesses. The new direct-down panel light illumination is simulated. The results completely conform to the national building lighting standards. In addition, the number of used LEDs is 30% of that of traditional panel light sources under the same power, and the thickness is reduced by 20 mm, greatly cutting down the production cost of LED flat light.