I have a project in mind where I would like to re-use LCD panels from old monitors to save them from landfills. I'd like to bypass the existing driver and implement my own controller to bypass all of the menus, source control, etc. I know how to drive LCDs on a technical level, but I'm unfamiliar with how standardized their interfaces are in production models. Will panels of the same resolution use the same ribbon cable regardless of brand or make of the monitor, or is there a lot of proprietary stuff going on here? I'd rather not take apart 20 monitors to find out :)
They have single, dual or quad LVDS interface, there's two different bit mappings and two bit depth options. And they may use different supply voltages for driving. And all that is still missing different options for driving the backlight. So no proprietary things, just many differences.
It is a bit standardised, but there are many variations, so much that some incompatibility may result in a non working display, or just fry the power supply (I've seen that).
For protocol, there is mainly LVDS (old) and eDP = embedded DisplayPort (new). High resolution display may need several channels. Some screens have EDID ROMs which allows for auto-detection of the screen geometry.
For backlight, some displays have an internal regulator that drives LED backlight, some have direct connections to the backlight diodes, and some use CCFLs with a separate high voltage regulator.
So, be careful. Having the screen datasheet is far less risky.
Get onto any Chinese LCD sourcing site, select 20 random LCDs, and download datasheets, that should give you an idea.
While this may vary depending on screen sizes, generations, and original intended use (e.g. laptop screen v. TV v. computer monitor), my limited experience with smaller sizes (around 7 to 10 inches) is that while there is a limited number of “protocols” (e.g MIPI DSI):
- There are a lot of parameters for the “standard stuff” such as number of channels and lanes;
- There’s a lot more variation when it comes to the signals relating to backlights;
- Even if the signals are all exactly the same, the actual pinout may vary a lot (number of connectors, number of pins, order of pins…).
Even when looking at two screens from the same manufacturer, for the same size, with apparently close characteristics, you can end up with completely different pinouts.
So while you can certainly design a board for each of those displays, you are probably going to have a hard time having a single board which is able to drive a large variety of different displays, even if it’s just a matter of changing the pinout and nothing else (and given trace length and other requirements for LVDS, this is not always trivial).
Unless you find a source of many displays of the exact same model, or the displays all use an interface which is more strictly defined (e.g. eDP), it’s probably going to be quite difficult.