and now i looked at the other pic, the calcs u made for that led comparison. pico you calculated for the worst Cree Scenario while driving them @ max current where they have their lowest Efficiency. recalcing for 350mA...you would Need 95W of cree to compete with 112W of the other cob -> cree more efficient...in that case. hehe so every one can put the Facts as he pleases
on the other Hand you would have to buy 95 crees and Drivers in that Scenario...dont think that would be perfectly cost efficient...
It was a 105 watts of Cree if I remember correctly and the comparison is still fair, I took the output of the bridgelux at its peak power and compared it to Cree's output at its peak power, how is that not a good comparison?
Here is a little right up I did on COBs the other day:
"I will explain to you a few of the concepts of operation I have formulated in my own mind. Firstly the article you linked me to is interesting and does raise a few good points, like the 3 watt chips used in the panels where way under efficient compared to 1 watters. There are two sides to this story, the first being, these chips suck but this is only looking at the bloggers facts at face value tho, I have looked myself into a lot of panel designs and one of the common practices manufactures will do, is run high watt chips well under the rated power. Now from their point of view, you could advertise a system with 30 x 3 watt diodes but never actually say its a 90 watt panel. You could then, some what hiding the fact that you are doing this by using a shitty PSU and connecting fans to the circuit bringing your over all power usage up to about the 90 watt mark.
I don't know what panel this guy tested on how but I know there are very good diodes available in a wide range of wattage's from less then one watt up to 10 even 20 watts. Poor design and questionable marking tactics has given a bad name to LED grow panels in general. I can assure you there are 3 watt chips that would be equal or better then to 3 x 1 watters.
The COB design really his a massive step into upping the power and control over LED light. I don't if you used to follow computer chip manufacturing back in the day, early 2000's but this is a lot like what is going on with these new LED chips. As they make diodes bigger and bigger things start to get out of hand with regard to current flow and utilizing different materials, things really would start to get out of control trying to push 10 amps through a single diode. COB are a master peace of power distribution on the micro level, they are using technology similar to computer chip dies, different packaging technics is allowing for higher heat dissipation, better bonding, higher temperatures and ultimatum high efficiency.
In the video you can see every stage of the chips illumination, we start by seeing the parallel diode banks energizing, when one bank is saturated it consumes the voltage drop and you have another bank energize. Power increases and then you final have a uniform voltage across the die, the chip works in the lossy state for quite a large in-cress in voltage, the diodes at this power are only working with them self's, the light as many point sources as there are diodes at this stage. When you get to the upper end of this state, this is where you see the diodes excite the color coating, the light starts to sharpen off almost, things are starting to increase in temperature around the diodes, this is the power level in which the diode start to couple with the plastic (I think it may be some sort of phosphor coating?). At this point the uniform coating and each individual LED is coupled to each other acting as one, your only limits will now be the failure temperature of the diodes or coating. Efficacy wise, think about hundreds of people pulling one load up a hill, as apposed to each person caring a portion of it individually, the individuals are highly effected by small changes in the environment, but using a single load and letting everyone work together gives the load much more momentum.
No one has to think what I say is correct, I could be very well talking out of my ass but always what I try to imagine is how to relate things you can observe into your everyday life concepts. I know in my head I understand this but weather this all can make scene in your head is another thing, I hope its helpful."
