spodosaurus said:
How would one go about connecting a laptop screen (screen works, laptop
is dead) to a desktop PC? I'm assuming it requires digital input, so
rewiring it to a VGA connector is not going to do the trick, right?
Thanks,
Ari
You start by tracking down the datasheet for the panel. If you don't
know the pinout on the interface, how to power the thing, you aren't
going to get too far. This is an example of an 18" panel.
http://www.trans2000.com/lcdspec/Nl12810207.pdf
In terms of connecting to a desktop PC, the standard interfaces aren't
the same as the one used on the panel. As near as I can figure, this
product comes close to doing what is required, so this gives you an
idea of the complexity. But I'm not even sure, if the interface
on the SGI monitor, is the same as a raw panel or not.
http://www.sharpertechnology.com/imagesProducts/EP1600DATASHEET.pdf
That card is used to convert from DVI-D to some kind of LVDS for an SGI monitor.
Your panel probably has an LVDS interface as well.
I don't really know anything about the display standards. A quick search
suggests the transmission concepts are the same (low amplitude differential
signalling). DVI-D is "transition minimized", and I think what that
means, is a DC balance and an "invert" bit are added to each pixel
transmitted. It appears the DVI link clock is a lot faster than the
LVDS flat panel one. The LVDS might not be transition minimized, so
the format per pixel could be shorter, and potentially DC coupled
(while the DVI looks like it might be equipped to be AC coupled).
Other places you can look for hints, are in the laptop chipsets
and application notes. Some are intended to drive an LVDS panel,
but typically, Intel doesn't go out of their way to explain
all the steps to make it work.
945GM datasheet. Look for references to LVDS.
ftp://download.intel.com/design/mobile/datashts/30921904.pdf
"Using 24-bpp LVDS Panels with Intel Mobile Chipsets for Embedded Applications"
http://www.intel.com/design/intarch/papers/315975.pdf
The second document gives some idea how an LVDS link works.
The function of DE, Hsync, and Vsync, in looking at a few panel
datasheets, seems to have some redundancy. I can find panels
that use Hsync/Vsync, and others that use DE (DataEnable - says
data is valid?) for synchronization purposes. I presume the panel,
when it receives the DE signal, is able to extract Hsync and Vsync
via some kind of digital PLL. DE should have a pattern on it, that
delineates lines and screens full of pixels.
It is probably going to cost you more than the panel is worth
to build it, but you'll learn a lot about handling high speed
signals, eye diagrams, error rates...
There is a DVI spec here, so you can see how DVI-D works.
http://www.ddwg.org/lib/dvi_10.pdf
Paul
