As the title suggests, this is a general comparison between the long time member of the solid-state lighting LumiLeds versus a relative new comer Cree. Lumileds was founded as a sub-division of Hewlett Packard, which was one of the fields of expertise thus spinning it off to a separate division. Lumileds was acquired by Phillips thus forming Phillips-Lumileds in 2009. Cree was formed in 1996 and since has spawned four centers including one located in Santa Barbara, California. I have actually had the pleasure attending a tech lecture on the newer chemistries being used to increase lighting efficiency of solid-state light output without increasing DC Voltage consumption at the Santa Barbara Tech Center Cree. Great city and great campus with good people developing ways to improve lighting efficiency and technologies.
My first experience with LED technology came in the form of a custom made Arc Flashlight using a 1-watt Luxeon emitter with an average output of 35-lumens at 500mA/H. Back in 2000, the consumption and output figures were reasonable, but there is room for improvement. White LEDs were a new technology and it was essentially a blue diode with a UV sensitive phosphor to create the white light output desired. The mixture of different phosphors creates both the quality of the white light (tint) and color temperature. The quality is the tint such as the amount of blue, yellow, or green added into the phosphor to create the color temperature desired. So basically if one takes this formula of mixing different phosphors, one can reach the level of tint associated with some of the CFL bulbs sold today. Another fact here is the type of phosphor used is rather similar to what is coated within the interior wall of a florescent light tube and bulb. That was the technology of the late 90s to early 2000s so what kind of strides in this field of lighting have been shown today.
Now in 2011, Luxeon and Cree technologies are the two primary heads that have started back in 2006 a race of competing lighting technologies. The launch of the XRLamp-E by Cree basically boasts an increase in lighting efficiency and output while consuming less current at 6-volts (White LED are normally powered between 3 to 9-VDC with no more than 1.5Amps of current). The diode is rated at 3-watts using 6VDC at 500-mA/H with a tested output of 85-lumens/watt measured at 1-meter free air (no additional optics). Compared to the 3-watt Lumiled sourced LED at the same consumption, the light output without optics was about 50-lumens/watt. 50-lumens per watt is still quite a bit of light, but unlike the compact florescent and incandescent light bulbs, heat generated can only be transfer by contact, which means a metal plate for heat sinking must be used otherwise the solid-state light will fail. This is one of the reasons why high-output LED flashlights get warm to hot in our hands.
Another example of heat generation with solid-state lighting technology would be the second experience with this type of lighting technology. In addition to the first Arc Flashlight that I still own to this day, I purchased the Arc-V, which is a five-watt Bin-Q-R (6000K color Temp) white LED Luxeon emitter powered by a single CR123A lithium cell and when in use, the light output is very high. 150-lumens of sustained output for about thirty minutes before going to moon mode of 50-lumens for another two to three hours. I know this from my experience with the Arc-V, which I still own to this day. I don't use the light much for fear of wasting away precious battery life with these rather expensive CR123A lithium batteries. Rechargeable CR123A are not recommended since these cells have a higher output curve and will destroy the power circuit that governed the LED and power consumption. This is not so much so with the Custom Arc-Flashlight with the 1-watt Luxeon emitter.
Heat generated by the Arc-I Custom (the 1-watt diode) would best be described as a good hand warmer after about two minutes of use. Constant use is still comfortable with bare hands so if one were to go out in the cold, all I have to do is turn on my Arc-I Custom and light up the places needing light and wait about two minutes. The Arc-V however is completely different story and I actually purchased the first generation of the Arc-V flashlight, so it basically has on and moon mode with the latter only activated when there is less than twenty percent battery capacity remaining. Once turned on, the Arc-V delivers an impressive amount of illumination with a rather tight 10-degree spot beam with a good deal of spill lighting. Great light output with a somewhat efficient architecture, however though after about thirty seconds, I would end up throwing the light onto the ground because it would be too hot to handle (literally). By too hot, with a temperature sensor attached to the body of the flashlight, the Arc-Vcan reach operating temperatures of 160-degrees Fahrenheit after thirty seconds of use. There is a temperature regulation circuit in the Arc-V, but doesn't kick in until the unit reaches about 180-degrees-F at which will automatically reduce output to 50% brightness (moon mode is about 10% brightness or 15-lumens or less than a watt). Even at 50% output, the Arc-V still operates at a temperature of 120-degrees-F, which I consider a hand cooker rather than a warmer. Even with gloves, this flashlight is not at all comfortable for use for any short period of time. This is my take on some of the earlier models of the Arc-Flashlights and things change since the Arc-V. Other companies now spawn different variations of the Arc-V design without the inherit high-heat drawbacks or short life (the Arc-V that I currently own is now at reduced brightness regardless of the condition of the battery due to the rather notoriously known short half-life of the Luxeon-V emitter) only because of driving the emitter to full output, these companies under-drive the LED to 80% while still delivering more than 200-lumens of light at 6000K color temperature.
Two-hundred lumens with a five watt Luxeon-V emitter was not bad or good since to drive to 5-watts, the control circuit within the Arc-V was set to 6-VDC step-up to 900-mA/H, which is slightly over than 5-watts driven and yet it still delivers only 150-lumens thrown at 1-meter. The optics at that time were developed by Lumileds and weren't made for such a high-flux LED so the spot beam was somewhat diffused hence the lower output rating. Around 2004, The Luxeon-III replaced the Luxeon-V as the new leader in high-flux solid-state lighting emitter with lower current consumption, higher output efficiency while having a tighter control tolerance of color temperature (between 4500 to 5000K). Higher efficiency as in less current consumption required to create the target output with the Luxeon-III emitter of 200-lumens or nearly 95-lumens/watt and 600-mA/H at 6VDC. With a Fresnel focused optic at the correct focal point of the emitter, the light output is further increased to nearly 130-lumens/watt with the same consumption rating. The 3-watt emitter is capable of being over-driven with a slight decrease in emitter life-span (100K-hours to 60K-hours when over-driven) and about 150-lumens/watt measured throw distance of 1-meter.
Heat is still a factor here as the Luxeon-III emitter was still a little hot to handle when the Arc-Flashlight (Arc closed its doors to restructure itself in 2006 to return in 2008) introduced the Arc-III in late 2004. Not as hot as the Arc-V, but hot enough to require gloves to handle for long periods of time. So having a very portable hand torch capable of delivering a massive amount of light without the bulk is a reasonable tradeoff for more than warm flashlight. Anyway the Luxeon-III emitter replaced the other versions until 2008 that is when Cree launched (this is to the best of my knowledge that is) the XR-Lamp-E.
Enter the World of the Cree XRLamp-E
Cree XRLamp-E is a 3-watt, high-flux/efficiency solid-state emitter with a new optically transparent (90% transmission efficient) epoxy with newer organic phosphor compounds to provide a sustained (4500K) color temperature range throughout the production line. High-efficiency in the form of lower voltage and current consumption required to deliver about 90-lumens/watt at 5VDC and 300-mA/H. Both high-flux and efficiency is the name of the game when Cree developed the XRLamp-E and at 90-lumens/watt (free air no optics), efficiency and high-output. Using an optic supplied by Lumileds (I conducted the test in a lab with other technicians), driving the Cree XRLamp-E to a full 3-watts at 6VDC and 1A/H(can be overdriven to 6VDC and 1.5A without decreasing life-span) allows for 170-lumens/watt average. The optic supplied is a 20-degree spot 1-inch Fresnel type with a close focal point hence the optic sits on top of the emitter dome. Another part of the efficiency component is the emitter pad used to dump away the heat generated and to my surprise, the heat sink pad used pulls the heat away from the emitter quite efficiently.
When properly mounted and driven, the Cree XRLamp-E can deliver the equivalent output of a 35-watt Halogen MR16 with a 30-degree flood beam (6VDC at 750mA/H) thrown at 2-meters. I decided to further test my idea by purchasing a Cree XRLamp-E custom MR16 direct drop-in for cabinet lighting and again to my surprise, the light output is quite impressive. When compared to the warmer 50-watt MR16 30-degree flood Halogen light, the single XRLamp-E emitter through a 30-degree Fresnel optic delivers a nearly equal output of light without the excessive heat output. Through a Newport Corporation Light Meter measured at 1-meter, the 50-watt MR16 Halogen delivers about 665-lumens. Through the Fresnel optic, the 3-watt Cree XRLamp-E driven at 6VDC and 750mA/H, the output at 1-meter was 556-lumens at 30-degree flood. Between the two numbers, yes the 50-watt Halogen delivers more lighting output, but one thing a light meter doesn't measure is the amount of heat thrown through the transmission of light energy. This is where LED lighting technology has the advantage over traditional glowing filament bulbs, however a great deal of aluminum is used to sink the heat away from the Cree emitter since LEDs light energy rating is lower than the filament type. Not to complicate the explanation of this, the simple answer is LEDs require heat sinking material in order to move heat away from the emitter to cool the light down.
As long as the emitter is cool, the life-span of the light is vastly increased to the degree that frequent replacement would not be a factor like with Halogen or compact florescent lights. That was one of the selling points with the Cree XRLamp-E Custom MR16 drop-in (with an integrated inverter) and I must say that this light is what I use for my cabinet lighting. Heat transmitted by light energy is not what I desire especially when I have items inside the cabinet that are sensitive to both UV and heat, which are qualities of Halogen lighting that are unavoidable unless there is such a thing as a cold glowing filament. So for a near 100-lumen reduction in light output, a 3-watt emitter consuming 3-watts of DC (less than a single watt in AC) versus 50-watts of glowing consumption and heat, I would rather choose the lesser of two evils.
The cost of replacing some or all of the Halogens and florescent bulbs in a single household with solid-state technology can be rather costly, but in the long-term, the replacement savings and energy costs will fully justify itself. Just think about the idea of ten 3-watt emitters each producing 500+lumens of light compared to a single 50-watt Halogen or three 28-watt compact florescent tubes delivering about the same lumen output (50W Halogen delivers about 80W of light output while a 28W CFL produces about 80W of light as well). Phillips-Lumileds developed drop-in bulbs in 2008 for use with the consumer household while Cree licensed their LEDs for use with Felt Electric. The drop-ins developed by Phillips-Lumileds are good, but the ones by Felt Electric powered by Cree XRLamp-E emitters are better. Both companies have great ideas with different directions in the way the emitters are implemented. The best way to experience this technology, purchase one or several for use in commonly used places such as the kitchen, den, dining room, and bedroom to understand the idea of how it works and the amount of light delivered.
I hope that this information was helpful and feel free to express your opinions and thoughts about this.
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