EEVblog #465 – LED LCD Panel TeardownPosted on May 1st, 2013 9 comments
What’s inside a modern LED backlight LCD panel from a 27″ computer monitor?
Forum Topic HERE
Some time ago I’ve made a white light frame (like the ones doctors use to see through Xrays photos) with a broken laptop LCD.
I have taken out only the pixel glass panel and replaced it with a clear 2mm thick glass (cost me around 1.5 euro or 2 dollars), leaving all the light diffusing layers. It’s really bright, I use it to align the holes in dual layer PCBs to use with the toner transfer method.
My panel was illuminated with cold fluorescent light though, but I had the inverter so no problem
With LED LCDs its basically the same thing, you just need to drive them.
Please do some experiments !
Please please please please
i’m considering using those panels on the celling as a lighting for my workshop.
or portable soft boxes for photography. ofcourse i will need quite few of them.
I read somewhere that more than 90% of the backlight is lost when passing through all the optics and filters. It would be nice to measure that, and if it is true, where is the light being lost.
I am not sure where you read that, but i guess it refers to the simple fact that the LCD has to filter/block the light to create pictures which are not just a uniform white area.
For every purely black pixel, the light would need to be blocked totally, without making adjacent pixels brighter. Well, for any pixel that is not 100% white, a certain amount of light has to be blocked.
The blocked light is wasted. If a technology would be invented that allows the LCD to reflect the blocked light back into the diffuser, much less light would be wasted. However, with such an approach you would face uneven lighting in situations where you have an uneven distribution of dark pixels in your picture. Since this applies to basically any picture LCD monitors/TVs have to show, this would be a rather severe problem.
In the end, to improve efficiency significantly you will have to switch to display technologies which do not rely on light filters to achieve different grades of brightness and colors (such as OLED, for example).
This is my favorite teardown yet! I can’t wait to see what you do next!
The R, G, B “picture elements” are called subpixels.
Great teardown and also great dumpster diving moments ;-).
Now I’d like to see a retina iPad display teardown. I can’t imagine how the driver connected to the massive amount of pixels.
thats amazing information
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