Thread: LED Backlight for LCD

I did my backlight with led's, & got the results I wanted & am happy with the backlight.... i looked into doing hundreds of small ones, as well as fewer large ones, & I don't remember all of my results, but I did come to the conclusion I would have more light going with larger 1 watt led's....

what I can tell you from experience playing with this though, is just putting an array like that behind an lcd will probably be very hotspotty... & you will need to add diffusion, which while helping the dispersion also cuts down on the final amount of light transmitted through the lcd.... a super bright light is needed, because you loose a huge percent of the light through diffusion & the lcd panel itself....

the way I did mine I wouldn't necissarily recomend to anyone, not because it isn't very effective, it is... but it's no where near the most efficient way of doing it, in cost & heat issues, not to mention the monstrosity it turned out to be.... no problem in my install, but not for the masses for sure....

from what I remember the heat issue will be there if your making as much light as you need to..... I wouldn't know, if you could get enough small super bright led's back there, how much of a heat issue you'd have.... from all of the research I did I don't think an array of just normal bright led's back there will be enough light.... & I think theres no way you'll have any hope of keeping an original housing.... you will need depth for this.

I think it would be cool for someone to try this.... if I do another one I will probably do it again with larger 1 watt led's, but this time attempt air cooled instead of liquid...., which is what I resorted to on my first one.... it get's hot..... real hot..... I wonder if that much light can be made with led's without the heat....

larger led's will need even more depth, & in playing with this I learned also that the dispersion improves as you back the led's away from the lcd... I think you need a lot of depth to get it to work good really... if you had an inch or so between that array & the lcd you'll need less difusion, which means more available light....

dimming leds is not a big issue, & will be the least of your problems...

did you start a thread of this project turbo?

you do need an extreme amount of light to really make it sunlight viewable....

just to add information to this thread, I learned about something so interesting & it pertains somewhat to what your ultimately looking to do, so I will add it here

the hot ticket in backlighting right now is not led's for super bright screens.... the real best thing out there are new & not easy to source yet at all, but they will help this situation big time when they are readily available.... when I actively searched for suppliers almost a year ago I got no where,, I even called china

I am talking about EEFL's... they look similar to CCFL's, but are very different in the way they work.... ccfl's need to each be connected to there own output from an inverter, they need specific start-up voltages & running voltages, they produce a lot of heat, & all of these things make it very difficult to make a solution with them.... eefl's on the other hand, are really cool... & I mean that literally too, because they produce no heat!!!! they look like ccfl's, but they appear as a capacitance to the power supply for them..... what this means is that you can actually string a bunch of these togeather in series, & then run them off one power supply real easily..... I haven't searched for these anytime recently, but I would imagine they are much closer to available by now, & may be worth looking into for someone who wants a super bright lcd.....

red, link in my sig

http://www.njfld.com/eefl.htm

Originally Posted by Wiredwrx

There was a VERY large thread or two from 2 guys who were attempting it. THey were trying different inverters and tubes. Someone also tried with a myriad of leds. I don't think anything ever came of it.

Michael

Nope, I didn't mean trying the direct illumination method...I mean trying the light guide method. I don't think anyone has tried that as of yet...but I'll search tonight and see.

yeah, theres some links out there & some sites that have info out there, mostly china, but actually getting them is the real issue... in time they'll be here, but I have no idea how much time

I have about 6" of space behind my screen, maybe I should just install a huge search lamp bulb behind the LCD

Originally Posted by ShawJohn

I have about 6" of space behind my screen, maybe I should just install a huge search lamp bulb behind the LCD

Provided that you have a clear light path to your screen and a properly diffused source, there's not really any problem with that solution at all.

In fact, I don't know why I haven't done that myself, now that I think about it. I have multiple inches of room behind my screen...really it will just be a matter of seeing whether I can move the LCD enough to get a clear path. Cooling would be much easier to accomplish with that much space as well...

Hmm...before I hijack the rest of this thread, I'm going to SEARCH and see if anyone else has experimented with such a solution. To hell with LEDs if an incandecent or flourcent source will work...I can make that as bright as I want.