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Author Topic: Digitiser not detecting pen through LCD panel  (Read 2186 times)
iridescentFUZZ
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« on: August 29, 2014, 12:35:03 AM »

So a little background information: I currently own an Intuos3 medium and a 10x6.25 Huion tablet. I also recently picked up an old laptop for dirt cheap, so I now have a 14.1", 16:10 LCD panel as well. From looking up the model number I've found a controller board for it, and I've also found it uses CCFL backlighting. The LCD panel is approximately 5mm thick.

As I have never had any experience with LCD panels and digitisers before and am not too keen on cutting either of my tablets, I thought the simplest test would be to place the LCD panel on top of one or both of my tablets to see how much it impacts the height at which the pen is detected, and/or ability to register clicks/pressure. I placed the LCD panel over the tablets, but did not cover the active area entirely. Much to my dismay, both the Intuos3 pen and the Huion pen are not detected through the LCD panel, but as soon as I move them off the area above the tablet(to the exposed active area), they are detected.

Now my LCD panel has a metal foil covering the entire back, which I have not peeled off, so I wondered if this was the issue. I then got a sheet of aluminium and placed it over the tablet and had the same results.

Any help would be appreciated as I would not want to go ahead and purchase a controller board if the pens are not even going to be detected through the display panel.
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Moldu
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« Reply #1 on: August 29, 2014, 01:12:27 AM »

Hello,

Yes these metal parts produce jitters and you have to at least put the electronic circuit not under the screen but next to it.
Tomorow perhaps I will make a short video in order to show you, if I can. Smiley
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Aerendraca
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« Reply #2 on: August 29, 2014, 06:47:42 AM »

Yes the metal covering the back of the screen is a problem. Like Moldu says, you should remove this metal (as it is blocking the radio frequencies used for communication between tablet and pen), and fold out the screens attached circuit (the Timing CONtroller - TCON board) so that it sits next to the screen.

An important thing to take note of is that you should make sure that no metal parts or circuitry on the screen can come into contact with any part of the tablets circuitry, otherwise you may end up killing the tablet, the screen and possibly even the computer (worst case).
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iridescentFUZZ
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« Reply #3 on: August 29, 2014, 02:48:21 PM »

Thanks for the help! Just thought I'd mention I don't plan at this stage to open up my tablet(will do that in a worst case scenario) so I won't have any circuitry of the tablet and LCD panel coming in contact. If I do end up opening up and cutting into the tablet, I've read a few build logs and question topics so I have a good idea of what to do.

Anyway, I peeled off the foil backing and here's what the back of the panel looks like:



I placed it on top of my tablet and was happy to discover that the pen is detected and clicks through the display perfectly, even through the circuitry and the metal strip circled in red at the bottom. I plan to match the size of the display to my tablet's active area using custom resolutions along with GPU scaling(will probably be tedious, but I should be able to get it to work).

One question I have is if the pen is detected through the circuitry now(with the display not receiving power/data), can I know if it will pass through the circuitry once I've bought my controller board and powered on the display?
« Last Edit: August 29, 2014, 02:51:58 PM by iridescentFUZZ » Logged
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