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Thread: Backlight upgrade with 2300mcd SMD LEDs

  1. #1
    FLAC
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    Backlight upgrade with 2300mcd SMD LEDs

    Alot of Chinese eBay sellers are offering high brightness white SMD LEDs (smaller than the typical 5mm led) in 50 piece quantities for less than $20:

    http://cgi.ebay.ca/ws/eBayISAPI.dll?...TODAY.m238.lVI

    I want to upgrade to LED because my screen is unreadable in direct sunlight (even after I did some 3m film upgrades), and my screen is too dim in the cold. I am interested in soldering a bunch of these small LEDs in a strip somehow and replacing my CCFL tube with them. One single LED measures 1.6 x 0.8 x 0.8 mm. Are those units correct? That seems incredibly small for something that can product 2300 mcd light output.

    I would probably have to improvise a way to solder these in a long strip so that I can slide the whole assembly in the place of the CCFL tube. I was thinking of taking two thin pieces of wire, then soldering the tiny LEDs in parallel onto the two thin wires. Then epoxy/glue the backside of the LEDs to act as an insulator as well as providing structural support. Feasible or no? Any other ideas how to physically mount these and other considerations that I should take into account?

  2. #2
    Low Bitrate
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  3. #3
    Constant Bitrate
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    Im thinking of doing the same thing. Pack as many surface mount white led's onto a strip that will fit where the stock ccfl tube previously was. this company has something that looks similar. I haven't had the chance to email them yet. If some one created such a product it would be very popular. A simple conversion that is no more complicated than replacing the ccfl of a lcd screen. then a plug in led backlight controller.
    If each led is normally 3 volts to operate, wire 4 in series and they can be run off 12V. then Connect the multiple strings of led's in paralel.
    Most cell phones have very bright led's that are no bigger than the tip of a pensil.
    If some one has the ability to make a multi layer surface mount circuit board for the different strings of led's. and the ability to solder such tiny surface mount components, it could be done and very profitable.

  4. #4
    FLAC
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    I never actually got around to doing this, been busy. And the tip of my soldering tip is getting kind of blunt...I dont think I would be very good at soldering those smd leds.

    However, if you go ahead with this I would love to hear your results and how you did it.

  5. #5
    FLAC
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    Bumping this thread, I just saw some 120 degree viewing angle smd white leds on eBay for cheap and I think Id like to go ahead with this project. I also have a spare backlight diffuser from a broken 7inch screen I can play with.

    What I am planning is to make a whole cluster of 9 x 11 white smd leds (so 99 total) which will shine straight out from the backlight diffuser. I dont think the led strip idea will be bright enough. Anyways, I did some rough calculations (I can show it if anyone is interested). Assuming 120 degree diffusional pattern per led, a plastic diffuser thickness of 0.9cm, and using a 9 x 11 array of these leds (to cover the 4:3 widescreen lcd), then according to calculations there will be a separation distance of about 1.3cm between each led. However, taking into account the thickness of the diffuser and the viewing angle of each led, it can be shown that each led will cover about 1.56cm. Just enough to ensure perfect coverage.

    Each led puts out 320mcd. Any criticism on why my idea wont work?

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