LED lighting application trends and heat dissipation problems Due to the continuous advancement of solid state lighting technology, LED luminous efficiency has been improved in recent years, and it has gradually replaced traditional light sources. At present, luminous efficiency has been chasing incandescent lamps and halogen lamps and continues to grow. As shown in Figure 1. Some companies have developed LED components with efficiency exceeding 100lm/W, which makes LED lighting applications more and more widely used. It has not only been applied to indoor and outdoor lighting, mobile phone backlight modules and car direction lights, etc. Applications such as high-wattage projection lights and street lights, large-size backlight modules, and automotive headlights. Due to the advantages of power saving, environmental protection and long life, the trend of LED light source in the future is becoming more and more obvious.
Figure 1 LED luminous efficiency trend comparison
In order to make the LED emit brighter light, it needs to input higher power. However, the current photoelectric conversion efficiency (WPE) value of the high-power LED is still limited, generally only about 15~25% of the input power becomes Light, the other is converted into heat. Since the LED chip area is small (~1mm2), the heat generation (heating density) per unit area of ​​the high-power LED is very high, even more serious than the general IC component, and the junction temperature of the LED chip is also (Junction Temperature). Greatly improved, it is easy to cause overheating problems. Excessively high junction temperature of the wafer will reduce the luminance of the LED, with the red light being most pronounced. It will also cause the wavelength shift of the LED to affect the color rendering, which will cause the LED reliability to be greatly reduced. As shown in Figure 2, the heat dissipation technology has become the bottleneck of the current LED technology development.
Figure 2 Relationship between component lifetime and wafer temperature
Ceramic Heater is ued in controllable aural various heat treatment furnace,to avoid the contact of elding burning outcome or to avoid the corrosion of furnace gas to heating element.The process(the conversion of elding burning or electric energy) is put into refractory steel tube and let amount of heat radiate by wall of tube.This device is called as heater tube.
Twist and turn resistance wire in axial direction,that is,the single resistance wire is bended to U shape,then in series or parallel connection mutually.This kind of electrothermal heater tube is called bending resistance wire heater tube.This tube,because fall of screening of resistance wire,in intratubal upper surface load,can insure prolong life span.
Ceramic heating element is a heating element and the ceramic through high temperature sintering, fixed together made of a heating element, according to the body temperature level to adjust the size of the resistance, which can be constant temperature in the set value, not overheating, with Energy saving, safety, long life and other characteristics. This heater does not light at work, no open flame, no oxygen consumption, soft air supply, with automatic temperature function. PTC ceramic heater output power in the 800-1250 watts, you can freely adjust the temperature, no light consumption when working, with automatic switching devices, energy efficient, energy safe. PTC ceramic heater uses most of the bathroom in the bathroom heater and some small bedroom heating. The rainy season takes into account the relatively dry indoor air in the northern part of the winter, the part of the heating in the bedroom PTC ceramic heater and humidifier function together, the introduction of humidification heater, warm hot air with the humid air blowing together , People feel very comfortable, and almost no noise. As consumers continue to improve the demand on the market derived from the novel products - fireplace - to simulate the flame, ceramic heating, resulting in warm air, creating a warm European and American style (power up to 1800W). The new appearance of a PTC ceramic heater appearance and ordinary oil-like heater like, but the use of enamel heat sink. Features a heat sink, thin shape, a protective cover, the use of security. Some of the more advanced products used in the room with infrared remote control, regular shutdown, fall automatically power and heating and other functions, can be regarded as fully functional.
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