Optimal Design of Secondary Optics for Narrowing the Beam Angle of an LED Lamp with a Large-Area COB-type LED Package

김봉준,; 김대찬,; 오범환,; 박세근,; 김봉호,; 이승걸,

doi:10.3807/kjop.2014.25.2.078

Cited by 1 publication

(1 citation statement)

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“…Thanks to such advantages, LEDs are widely used in various kinds of indoor and outdoor lighting, indicator lights, and display devices [2][3][4][5][6]. However, since the luminous flux emitted from an LED has a Lambertian distribution, secondary optics for controlling the luminous flux are necessary to form a desired illuminance distribution on a target plane [7].…”

Section: Introductionmentioning

confidence: 99%

Design Method for a Total Internal Reflection LED Lens with Double Freeform Surfaces for Narrow and Uniform Illumination

Yang¹,

Park²,

Beom‐Hoan³

et al. 2016

Journal of the Optical Society of Korea

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In this paper, we propose a novel differential equation method for designing a total internal reflection (TIR) LED lens with double freeform surfaces. A complete set of simultaneous differential equations for the method is derived from the condition for minimizing the Fresnel loss, illumination models, Snell's Law of ray propagation, and a new constraint on the incident angle of a ray on the light-exiting surface of the lens. The last constraint is essential to complete the set of simultaneous differential equations. By adopting the TIR structure and applying the condition for minimizing the Fresnel loss, it is expected that the proposed TIR LED lens can have a high luminous flux efficiency, even though its beam-spread angle is narrow. To validate the proposed method, three TIR LED lenses with beam-spread angles of less than 22.6° have been designed, and their performances evaluated by ray tracing. Their luminous flux efficiencies could be obviously increased by at least 35% and 5%, compared to conventional LED lenses with a single freeform surface and with double freeform surfaces, respectively.

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