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01/06/2011

LED tube ligh

 

Power LED light LED lamp life determines the constant current source LED driver drives is the best way, using constant current source drive, not in the output circuit current limiting resistor in series, LED current is not flowing through the external power supply voltage change, environment temperature changes, as well as the impact of discrete LED parameters, which can adhere to the current constant, with plenty to play a variety of outstanding features LED. LED constant current power supply used to power a LED lamp, as during the power will automatically detect and control the current flowing through the LED, thus, do not worry too much in the power of the instant the current flows through the LED, do not have to worry about the load short-circuit burn out the power.

Edit this paragraph thirteen,LED Ceiling Light energy-saving 1, LED light source with high luminous efficiency luminous efficiency comparison: incandescent, halogen light efficiency is 12-24 lumens / watt, fluorescent light of 50-70 lumens / watt sodium lamps of 90-140 lm / W, Most of the electricity into heat loss. LED light effect: can be sent to 50-200 lm / W, and the monochromatic light is good, narrow spectrum, without filtering, can be directly sent colored visible light.

Transition coatings
  Many LED semiconductor chips are potted in clear or colored molded plastic shells.LED flood light The plastic shell has three purposes:
  Mounting the semiconductor chip in devices is easier to accomplish.
  The tiny fragile electrical wiring is physically supported and protected from damage
  The plastic acts as a refractive intermediary between the relatively high-index semiconductor and low-index open air.

The third feature helps to boost the light emission from the semiconductor by acting as a diffusing lens, allowing light to be emitted at a much higher angle of incidence from the light cone, than the bare chip is able to emit alone.
  Efficiency and operational parameters
  Typical indicator LEDs are designed to operate with no more than 30–60 mW of electrical power. Around 1999, Philips Lumileds introduced power LEDs capable of continuous use at one W. These LEDs used much larger semiconductor die sizes to handle the large power inputs.LED spot light Also, the semiconductor dies were mounted onto metal slugs to allow for heat removal from the LED die.

One of the key advantages of LED-based lighting is its high efficacy,[dubious – discuss] as measured by its light output per unit power input. White LEDs quickly matched and overtook the efficacy of standard incandescent lighting systems. In 2002, Lumileds made five-watt LEDs available with a luminous efficacy of 18–22 lumens per watt (lm/W). For comparison, a conventional 60–100 W incandescent light bulb emits around 15 lm/W, and standard fluorescent lights emit up to 100 lm/W. A recurring problem is that efficacy falls sharply with rising current. This effect is known as droop and effectively limits the light output of a given LED strip light, raising heating more than light output for higher current.

In September 2003, a new type of blue LED was demonstrated by the company Cree Inc. to provide 24 mW at 20 milliamperes (mA). This produced a commercially packaged white light giving 65 lm/W at 20 mA, becoming the brightest white LED commercially available at the time,LED tube light and more than four times as efficient as standard incandescents. In 2006, they demonstrated a prototype with a record white LED luminous efficacy of 131 lm/W at 20 mA. Also, Seoul Semiconductor plans for 135 lm/W by 2007 and 145 lm/W by 2008, which would be nearing an order of magnitude improvement over standard incandescents and better than even standard fluorescents. Nichia Corporation has developed a white LED with luminous efficacy of 150 lm/W at a forward current of 20 mA.
  Practical general lighting needs high-power LEDs, of one watt or more. Typical operating currents for such devices begin at 350 mA.