Should have paid more attention in physics class, but does anyone know of a way to roughly estimate the resulting brightness in a screen from having N LEDs having a specific brightness? Can you do a simple ratio, such as:
N * efficiency * BrightnessOfLED * AreaOfLED = AreaOfScreen * BrightnessOfScreen
I think Im going to pick up a bag of these 2500 mcd SMD LEDs and solder them myself, simply because I want to cram as many of these babies as I can into the screen. Cheap sunlight visibility, here I come =)
http://cgi.ebay.ca/50-PCS-1206-SMT-S...item5ad4351c31
how are you doing the connection nobb? are you making your own pcb?
your idea could work as well if we can make our own pcb.
i went through that same seller and found 9000 mcd lights as well, what do you guys think?
http://cgi.ebay.com/ebaymotors/100-P...#ht_3229wt_816
Well heck, I ordered the original strip. I'm going to run it off unregulated power in the daytime to get some extra brightness and disconnect the inverter to lower any RFI.
From the pics, it looks like the CCFL runs inside the plastic frame. Those are approx. 3mm. where the LED would protrude. Maybe 4mm max depth there. The metal frame that goes over the plastic fits over it very close. The flexible strip plus resistors is probably a tight fit. I would think anything larger like a PCB is going require a lot more work. Tape, glue, mess...
9000 mcd!!! Crazee! It's expensive as heck though. I would suspect you would need some sort of cooling for that, maybe bond the LEDs to a copper or alu strip. I really wish I could visualize how bright 2500 or 9000 mcd is. Im kind of skeptical that 2500 mcd LEDs are enough.Originally Posted by Punky
EDIT: I dont think that seller is rating his LEDs properly. Both the 2500 and 9000 mcd leds draw the same current at the same voltage. Looks like a copy n paste job.
I wasnt really planning on making my own PCB, I have no idea how to do that. I was just going to epoxy the SMD LEDs to a strip of high temperature Kapton tape then join the electrical connections with a strip of steel wire. Ill probably run it straight off the +12v going into the screen. Im planning to have a top and bottom strip of LEDs. Half of the strips will always be on, then the other half maybe controlled by how bright it is outside (via a photoelectric sensor).
these leds are 3.6V which means that each one if you are going to fit them in parallel then each one would need a resistor to drop the voltage from 12V to 3.6V. that'll would be one hell of a job if you ask me. typically they do 4 led in series + 1 resistor on those pcb, and do a bunch of them in parallel. everything looks nice and thin on the pcb because they're multi-layered, if you were to do this with hobbyist material, it'll be gigantic.
I dug up a previous pioneer of this technology (turbocad6) and this thread has some intersting stuff with led backlit that i've been learning from.
800X1280 narrowscreen???
Now that I think about it, Im kind of hesitant that this will work. I remember a while back I bought a bag of LEDs because I wanted to upgrade my backlight. I just checked my invoice from eBay and these LEDs were actually 13000 mcd, similar to these:
http://cgi.ebay.ca/200-pc-3mm-white-...item335018239e
I backed out of this project because even with a whole strip of these 13000 mcd LEDs, they still were not as bright per unit length as a standard ccfl tube. I'm not quite sure how these eBay sellers rate their LEDs. There's even some 20000 mcd LEDs here:
http://cgi.ebay.ca/100-x-5mm-White-L...item3ca601dba5
if they are at least as bright as the ccfl then its worthwhile because then we have instant warmup lcd.
i was thinking lining the entire led with many strips of leds to compensate the light output, this means that i'll have to somehow remove/replace the 3mm clear plastic layer.
I was also thinking about it last night, two things left for me to look out for. Since i'll be using these bigger smd5050 led strips and lots of them 10 strips x 16cm (roughly 90 leds in there) it might get hot.
Another thing is, will there be hot spots? do i need other films to disperse the lights?
Anyone with experience please share some info!
The brightness rating thing is confusing me. It seems that in picking the LEDs, you have to be careful on how it is rated. In that eBay listed I posted above, the luminous intensity for those SMD LEDs is 2500mcd but only at an angle of ~60 deg. The LEDs that the OP used are only 1200 mcd but at an angle of 180 deg. If we sub those values into the calculator here, we can see that at first glance, the OP's LEDs appear to be half as bright (from the mcd rating) but in reality they will have about double the luminous flux as the cheap made-in-china eBay ones.
http://led.linear1.org/lumen.wiz
i've emailed the seller about the ebay leds (http://cgi.ebay.com/ws/eBayISAPI.dll...:X:AAQ:US:1123) these are twice as dense, which is probably as dense as you can place them.
they told me that these leds are 1400mcd per light, which sounds reasonable for 120* viewing angle.
so 90 of these are would be interesting, I'm planning to get 1 x 5m reel for about 120 usd shipped, and sell the rest. I'd probably need about 1.5m.
I'm still a bit worried about the heat and light dispersion issue.
Nice mod.
BTW, to control dimming of those LEDs, better go with the PWM something like this.
That is the controller you can build for 5 bucks in part. I use that controller to dim my Supra LED light. For info on how to build 1, check my Supra PC link. There is a link to hidplannet LED section that has more detail.
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