Light emitting diode (LED) has been recognized as an applicable light source for indoor and outdoor lighting, city
beautifying, landscape facilities, and municipal engineering etc. Conventional LED has superior characteristics such as
long life time, low power consumption, high contrast, and wide viewing angle. Recently, LED with high color-rendering
index and special spectral characteristics has received more and more attention. This paper is intended to report a solar
spectrum simulated by multichip LED light source. The typical solar spectrum of 5500k released by CIE was simulated
as a reference. Four types of LEDs with different spectral power distributions would be used in the LED light source,
which included a 430nm LED, a 480nm LED, a 500nm LED and a white LED. In order to obtain better simulation
results, the white LED was achieved by a 450nm LED chip with the mixture of phosphor. The phosphor combination
was prepared by mixing green phosphor, yellow phosphor and red phosphor in a certain proportion. The multichip LED
light source could provide a high fidelity spectral match with the typical solar spectrum of 5500k by adjusting injection
current to each device. The luminous flux, CIE chromaticity coordinate x, y, CCT, and Ra were 104.7 lm, 0.3337, 0.3681,
5460K, and 88.6, respectively. Because of high color-rendering index and highly match to the solar spectrum, the
multichip LED light source is a competitive candidate for applications where special spectral is required, such as
colorimetric measurements, visual inspection, gemstone identification and agriculture.
With the development in material growth, device fabrication and packaging of LEDs, emission spectral of LED is able to cover the visible spectrum. In addition to the well-known lighting applications of LED, display is also one of the important applications of LED. In contrast with LCD, LEDs display has better contrast ratio, higher response rate, etc., which makes LEDs along with other self-illumination technologies an ideal candidate in making display panel. With the popularization of HD and Ultra HD standard, display panel with better image quality is needed. The number of pixels of the panel needs to be increased and the size of each pixel needs to be minimized. In this paper, we prepared a LED full-color display panel based on a 32×32 LED matrix with typical pixel size of 0.5mm. LED full-color display array with small pixel was obtained by mounting red LEDs, green LEDs and blue LEDs directly onto an isolating substrate such as sapphire . In addition, the substrate has metalized pads and connection before the matrix was connected to control unit. The control line and the column data line are prepared on the substrate, and there is an effective electrical insulation layers between them. The isolation layers consists of a SiO<sub>2</sub> layer of 1000nm and polyimide layer of 3000nm. Polyimide as an important electrical insulating layer, we study some properties of it, such as :PI amination rate as a function of the curing temperature, PI resistivity as a function of the curing temperature and the punction electric field intensity of PI as a function of the film thickness of PI.
Spectral power distribution together with color consistency and constancy of natural light is studied and simulated before the white-light LED systems are fabricated to reproduce the natural light. The model with 3, 4, 6 and more primary LEDs based on the real measured spectrum and theoretical spectrum are analyzed. The spectral power sensitivity relation between the LEDs with different wavelength and color characteristic is analyzed. This research simplifies the approach of visible spectrum reconstruction which is an efficient way to use in the design and realization of LED-based luminaire.
Thanks to the development in epitaxial growth, chip fabrication and packaging of LEDs, emission spectral of the device
is capable of covering the visible spectrum. Therefore, Light-emitting diode (LED) is currently undergoing a growing
interest in many applications, such as lighting. Besides lighting, LEDs offer a wide range of potential applications
including display. In contrast with LCD, LEDs display has better contrast ratio, higher response rate etc which makes
LEDs along with other self-illumination technologies an ideal candidate in making display panel. Due to the
popularization of HD and Ultra HD standard, display panel with better image quality is needed which means the number
of pixels of the panel needs to be increased while the size of each pixel needs to be minimized. In this paper, we describe
the design and fabrication of a colour tuneable and addressable LED micro display based on a 16×16 and 32×32 LED
matrixes with typical pixel size of 0.7 and 0.5mm respectively.