Collimating lamp with well color mixing of red/green/blue LEDs

Abstract:We analyze the color uniformity in the far field of spotlight systems to estimate visual perception with a merit function derived from human factor experiments. A multi-colored light-emitting diode (LED) light engine with different light mixing levels is combined with several reflectors and total internal reflection (TIR) lenses. The optimized systems are analyzed at several color uniformity levels with regard to the efficiency, peak luminous intensity and dimensions. It is shown that these properties cannot all be optimized at the same time. Furthermore, excellent color uniformity can be reached by a light mixing layer in the light engine or by adding mixing elements to the secondary optics.

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“…In general, color uniformity evaluation in spatially defined far fields is based on differences with respect to mean color values [4,5].…”

Section: Color Uniformity U Sl In Spotlightsmentioning

confidence: 99%

Color uniformity in spotlights optimized with reflectors and TIR lenses

Teupner¹,

Bergenek²,

Wirth³

et al. 2015

Opt. Express

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“…A similar function, the root-mean square color difference is used by Sun et al 12 for the evaluation of RGB-LED spot lights. The color deviation is used to specify the color uniformity within the spot lights.…”

Section: Mathematical Evaluationmentioning

confidence: 99%

Merit function for the evaluation of color uniformity in the far field of LED spot lights

Teupner

Bergenek

Wirth

et al. 2014

Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVIII

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The scope of the present paper is the derivation of a merit function which predicts the visual perception of LED spot lights. The color uniformity level Usl is described by a linear regression function of the spatial color distribution in the far field. Hereby, the function is derived from four basic functions. They describe the color uniformity of spot lights through different features. The result is a reliable prediction for the perceived color uniformity in spot lights. A human factor experiment was performed to evaluate the visual preferences for colors and patterns. A perceived rank order was derived from the subjects' answers and compared with the four basic functions. The correlation between the perceived rank order and the basic functions was calculated resulting in the definition of the merit function U sl . The application of this function is shown by a comparison of visual evaluations and measurements of LED retrofit spot lamps. The results enable a prediction of color uniformity levels of simulations and measurements concerning the visual perception. The function provides a possibility to evaluate the far field of spot lights without individual subjective judgment.

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“…In recent decades, the higher emitting rate and low pollution characteristics of LED lights have gradually led to their replacing regular incandescent bulbs and becoming the new generation light source [1][2][3][4][5][6][7]. However, various color evaluation methods have proven to be inconsistent or even inappropriate in previous studies.…”

Section: Introductionmentioning

confidence: 99%

How Smart LEDs Lighting Benefit Color Temperature and Luminosity Transformation

et al. 2017

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Luminosity and correlated color temperature (CCT) have gradually become two of the most important factors in the evaluation of the performance of light sources. However, although most color performance evaluation metrics are highly correlated with CCT, these metrics often do not account for light sources with different CCTs. This paper proposes the existence of a relationship between luminosity and CCT to remove the effects of CCT and to allow for a fairer judgment of light sources under the current color performance evaluation metrics. This paper utilizes the Hyper-Spectral Imaging (HSI) technique to recreate images of a standard color checker under different luminosities, CCT, and light sources. The images are then analyzed and transformed into interpolation figures and equal color difference curves. This paper utilizes statistic tools and symmetry properties to determine an exponential relationship between luminosity and CCT in red-green-blue (RGB) LED and OLED light sources. Such a relationship presents an option to remove the effects of CCT in color evaluation standards, as well as provide a guide line for adjusting visual experience solely by adjusting luminosity when creating a lighting system.

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Collimating lamp with well color mixing of red/green/blue LEDs

Cited by 47 publications

References 18 publications

Color uniformity in spotlights optimized with reflectors and TIR lenses

Color uniformity in spotlights optimized with reflectors and TIR lenses

Merit function for the evaluation of color uniformity in the far field of LED spot lights

How Smart LEDs Lighting Benefit Color Temperature and Luminosity Transformation

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