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Difference between revisions of "LED"
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As more power is applied, more waste heat is generated and must be carried off. At some point a LED will be overdriven which will shorten its life from the tens of thousands of hours a properly driven LED should last. As the LED is overdriven the yellow phosphor on the LED starts to burn and "angry blue" light is emitted. If the light is turned off quickly, the LED may avoid permanent damage, but otherwise the LED will literally burn with brown spots on the LED. Generally when that happens, the maximum output will now be significantly lower. | As more power is applied, more waste heat is generated and must be carried off. At some point a LED will be overdriven which will shorten its life from the tens of thousands of hours a properly driven LED should last. As the LED is overdriven the yellow phosphor on the LED starts to burn and "angry blue" light is emitted. If the light is turned off quickly, the LED may avoid permanent damage, but otherwise the LED will literally burn with brown spots on the LED. Generally when that happens, the maximum output will now be significantly lower. | ||
== | ==LEDs in Flashlights== | ||
Early | Early LEDs did not give off that much light, but they were efficient and they would last many thousands of hours before burning out. As they got brighter, they started making their way into flashlights. The classic LEDs were 5mm in diameter encased in clear epoxy resin with a round head. As the LED inside gave off light, the rays were shaped by the round head to go straight ahead. Many keychain flashlights use a simple LED like that. These are usually named as 3 mm or 5 mm LED's. The [[Fenix]] E01 uses a 5mm Nichia LED. To get additional brightness, some flashlights would combine multiple LED's in the head of the flashlight and maybe include some kind of reflector to shape the light. | ||
[[File:sscp7led.jpg|thumb|Seoul Semiconductor P7 multi-die LED]]High power LED's were developed to handle higher currents and produce brighter light. They lost the clear plastic shell and had to be mounted to a metal base to draw heat away from the LED before it could burn itself out. Lumileds Luxeon I was a 1-watt LED producing 30 to 60 lumens and was followed by the 3-watt Luxeon III (60-90 lumens, requiring more power than the Luxeon I). They also produced the K2 which could be driven at even higher currents for more output. | [[File:sscp7led.jpg|thumb|Seoul Semiconductor P7 multi-die LED]]High power LED's were developed to handle higher currents and produce brighter light. They lost the clear plastic shell and had to be mounted to a metal base to draw heat away from the LED before it could burn itself out. Lumileds Luxeon I was a 1-watt LED producing 30 to 60 lumens and was followed by the 3-watt Luxeon III (60-90 lumens, requiring more power than the Luxeon I). They also produced the K2 which could be driven at even higher currents for more output. | ||
To compete with Luxeon, Cree started producing the Cree 7090 XR-E in 2006 with various bins (P4, Q3, Q5). The XR-E produces twice as much light as a Luxeon III at the same voltage and current. Seoul Semiconductor (SSC) produced the Seoul SSC P4 using Cree's LED die. In 2007, Lumileds responded with the the small and very efficient Luxeon Rebel series of | To compete with Luxeon, Cree started producing the Cree 7090 XR-E in 2006 with various bins (P4, Q3, Q5). The XR-E produces twice as much light as a Luxeon III at the same voltage and current. Seoul Semiconductor (SSC) produced the Seoul SSC P4 using Cree's LED die. In 2007, Lumileds responded with the the small and very efficient Luxeon Rebel series of LEDs. | ||
To get even more brightness, rather than combine | To get even more brightness, rather than combine LEDs into one flashlight, multiple LEDs could be mounted to the same chip. These multi-die LEDs produce 400 to 900 lumens. The Luxeon V was one of the first and produced 100-140 lumens. Seoul produces the P7 and Cree produces the MC-E, each with 4 LED's on a chip. | ||
Luminus developed the SST-50 and SST-90, larger | Luminus developed the SST-50 and SST-90, larger LEDs requiring currents of 5 amps and more, but giving off a lot of light. Cree responded with the XM-L which has a larger (than the XR-E/XP-E series of LEDs) single die and can be driven up to 3 amps. | ||
==Bins== | ==Bins== | ||