In this paper, we present a luminaire design with anti-glare and energy-saving effects for sports hall. Compared with traditional lamps using in a badminton court, the average illuminance on the ground of the proposed LED luminaire is enhanced about 300%. Besides, the uniformity is obviously enhanced and improved. The switch-on speed of lighting in sports hall is greatly reduced from 5-10 minutes to 1 second. The simulation analysis and the corresponding experiment results are demonstrated.
A novel light luminaire is proposed and experimentally analyzed, which efficiently mixes and projects the tunable light from red, green and blue (RGB) light-emitting diodes (LEDs). Simultaneous light collimation and color mixing is a challenging task because most collimators separate colors, and most color mixers spread the light beam. We performed an experimental study to find a balance between optical efficiency and color uniformity by changing light recycling and color mixing.
A planar-exit lighting surface is not only used in the luminaires but also useful in the display backlights and other
illumination systems. Most planar-exit lighting surfaces are made by edge-lit with line light source or 1-D LED array. If
it is not edge-lit type, the light source can be two-dimensional, but a cavity is required. In this paper, a high-efficiency
cavity providing extremely high energy transmittance with photon recycling is reported and demonstrated. The cavity
contains a diffuser and the high reflectivity surfaces. The optical efficiency of the cavity is calculated by a formula with
considering photon recycling. Furthermore, various kinds of diffusers are applied to change the optical transmittance as
well as the light pattern. When the reflectivity of the inner wall of the lighting cavity is about 96 %, the optical efficiency
of the cavity is higher than 90 % with several diffusers. The experimental measurement as well as the calculation is
demonstrated in the paper.
In this paper, we propose and demonstrate a novel design to make color mixing and projection of RGB LEDs. The
optical elements include a high reflective light pipe, a volume scattering diffuser and a TIR lens. The system optical
efficiency is around 46 % while the color is well mixing for the cases at the CCTs of 6500K, 4500K and 3000K.
In this paper, we demonstrate a method to calculate the phosphor particle numbers and study the relationship among
phosphor particle numbers, light output and correlated color temperature (CCT) of LEDs under remote package type and
dispensing package type. We also discuss the influence of the thickness and concentration of phosphors on the
performance of LEDs. We compare the various thicknesses and concentrations to check the resultant CCT and the output
flux, where we can see that the lumen output is almost equal as the phosphor particle numbers is similar with the CCT at
6500±200 and 5000±100 K under the remote package type.
In this paper, based on Monte Carlo ray tracing we simulate light extraction efficiency and directionality of the light
pattern of GaN LEDs implanted with micro-pyramid structure with or without lens encapsulation. We have shown that
micro-pyramid structures at some specific slanted angles in the LEDs are useful to increase effective flux utilization
through enhancement of both the directionality and light extraction efficiency.
A single-chip white light LED is commonly modeled by considering the phosphor coating as a homogeneous
Lambertian light source. However, this approach leads to an incorrect optical simulation of phosphor-coated multi-chip
LEDs due to the presence of a previously unreported spatial distribution of emission spots across the phosphor layer. We
introduce "weighting" factors based on position-dependent light strength across the phosphor surface in order to improve
the model accuracy. Following the modeling algorithm in the mid-field region, we have built up a precise and practical
optical model by using Monte Carlo ray tracing and weighting factors. We measure the LED radiation distribution at
several representative distances to test the model performance. In all cases, the accuracy is higher than 99.5% in
normalized cross correlation between the simulated pattern and experimental measurement.
A direct or bottom LED backlight is a key concept in large area LCD displays because it does not use a light guide, is
flat, and is easy to assemble. In this paper, a method of luminance management for a bottom LED backlight is proposed
and demonstrated. We analytically calculate both the power consumption and brightness uniformity in function of: screen
brightness, screen size, backlight thickness, transmittance of the LCD panel, reflective cavity efficiency, gain and cone
angle of enhancement films, LED array configuration, and the average luminous flux and radiation pattern of a single LED.
Moreover, a 42-inch LCD television with this backlight design approach is made and demonstrated. The bottom backlight
incorporates an array of RGGB 4-in-1 multi-chip LEDs within a highly reflective box behind a diffuser and a dual
brightness enhancement film. We predict with an accuracy of 94% the brightness uniformity and with 96% the luminance