Future technology trends in semiconductor lighting
LEDs are compact, lightweight, low-drive, full-color, long-life, high-efficiency, vibration-resistant, and easy to control light, providing superior conditions for lighting systems designed for different locations and purposes. People are accustomed to seeing things under the sun. For general lighting, people need mainly light sources that are close to the quality of sunlight, so white LEDs are an important indicator of semiconductor lighting technology. Since the single LED has low power and low brightness, it is not suitable for use alone. Therefore, it is necessary to assemble a plurality of LEDs together to design a practical LED lighting system. However, there is still a certain distance between the requirements of white LEDs and general lighting, and there are still many technical and cost issues that need to be solved urgently.
Main technical overview of semiconductor lighting system 1) Thermal management of lighting system is generally called LED as cold light source. This is because LED lighting principle is the process in which electrons directly emit photons through recombination without heat. However, due to the existence of Joule heat, LEDs are accompanied by heat while illuminating, and for high power and multiple LED applications, the heat accumulation is small and can not be underestimated. LEDs are different from traditional lighting such as incandescent lamps and fluorescent lamps. Light source, too high temperature will shorten or even terminate its service life. Moreover, LEDs are temperature-sensitive devices. When the temperature rises, their efficiency drops sharply. Therefore, system structure design and heat dissipation technology development are also issues that LED applications need to face. Since forced air cooling is generally undesirable in light sources, heat sinks and other methods of enhancing natural convection cooling play an increasingly important role in LED lamp and light source design as input power increases.
2) Improve color rendering At present, white LEDs are commonly used to emit blue light LEDs superimposed with blue light-emitting yttrium aluminum garnet (YAG) phosphor powder, which is synthesized into white light. Since the luminescence spectrum contains only two spectra of blue and yellow, there is a problem that the color temperature is high and the color rendering index is low, which does not meet the general lighting requirements. The sensitivity of the human eye to chromatic aberration is much higher than the sensitivity to light intensity. For illumination, the color rendering of a light source is often more important than the luminous efficiency. Therefore, adding an appropriate amount of red-emitting phosphor powder and maintaining high luminous efficiency is an important issue in LED white light illumination.
3) Secondary optical design of the luminaire system Traditional lamps have long used incandescent lamps and fluorescent lamp sources as reference materials to determine the optical and shape standards of the luminaires. Therefore, LED luminaire systems should consider abandoning the assembly of traditional luminaires and LED illuminating modules. In a way, considering the optical characteristics, different lamps are specially designed for the LED light source. The design of the optical system mainly includes the following aspects: (1) According to the requirements of the illumination object and the luminous flux, determine the shape of the optical system, the number of LEDs and the size of the power; 2 design a plurality of LED lighting tubes into a point light source, a ring light source or The secondary light source of the surface light source calculates the illumination optical system according to the combined secondary light source; 3 the light distribution control of each LED tube on the secondary light source that constitutes the illumination optical system design is very important.
Since the beam emitted by the LED is concentrated, it is easier to control, and the reflector is not required to be concentrated, which is advantageous for reducing the depth of the lamp. For example, with a flat mirror optical system, a large surface can be illuminated with only 1 or 2 LEDs, and the depth of the lamp is very thin. With the light guide technology, the LED is directly mounted next to the light pipe, which can greatly reduce the light source and other components. The volume occupied makes an ultra-thin luminaire.
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