I've been pondering making use of the still-functional portions of cracked displays... The original idea was for a (laptop?) TFT LCD which is cracked in the bottom-half but still displays something in the top-half + a glass-cutter.
Could be pretty groovy to have a wide and really short display for various purposes, clip it to the top of the laptop's built-in screen... Hang it under, or to the left of, a desktop display... Throw status-indicators up there, like a CPU meter, or whatnot. (Maybe the OS's Application-Dock?) Honestly don't know whether the screen will continue working after cut, but it'd be an interesting experiment). I Don't actually own a cracked LCD display, so this is all just preparatory-experimentation up to this point.
Try it yourself and let me know what happens! Feel free to use my avr-edid-spoofer and/or a screen-timing utility like SwitchResX to see if the system can handle such a strange resolution, and whether the screen is capable of syncing as such. I'd love to hear the results and/or give some tips.
Initial Experiments: Using my totally-functional built-in display...
Using SwitchResX, I changed the screen-timing such that the Vertical Active lines is 500 (actual is 1050). Using the prior values for the VSync and VPorches led to a non-syncing display. BUT bumping the total number of lines back up to the original value (1058 with VSync and porches) seems to work great (the rest, which resembles a lower-crack in a display, is black). In other words, I've modified this 1050-line display to the top 500 lines by maxing out the V Front Porch (63) and V Sync Width (63), and throwing the remainder (432) into the V Back Porch, such that the total number of lines adds up to the original value (1058).
So, it seems entirely plausible that a cracked-display might be usable as a short secondary display... In this experimental case, the system recognizes the resolution as 1400x500, so there's no reason to worry about the system thinking it can put things off-"screen". Entirely plausible.
Easier-still, just mount it as-is behind the main display with the working/visible part sticking past the edge. No cutting required. (Though, I am curious what'd happen if a screen is cut short, and ultimately it would look better in a nice housing, etc. Though it might be a little difficult to get the backlight aligned?).
Latest Result:
I ordered a VGA -> LVDS converter for $6 on ebay...
The VGA -> LVDS converter is an awesome piece of engineering in a single-chip. I can't see any way to make it work with a *horizontally-cut* display, except to use it at its original full-resolution. But it looks like similar timing-adjustments as above could be used in a few cases, with the added benefit described earlier of reporting to the computer that it has a smaller physical size than its original resolution.
E.G.
The crack is on the right-side of the screen, but there's a definite usable vertical column to the left
Using a timing-adjustment-program like SwitchResX, subtract the unusable pixels from the Horizontal-Active Pixels, and throw them into the Horizontal Front Porch.
The crack is on the top, but there's a definite usable horizontal area at the bottom...
Similarly, throw the unusable pixels into the Vertical-Front-Porch
As far as other cracks/usable columns,
There may be a problem with the resyncing system built in to the VGA->LVDS converter. This chip is designed to take in an arbitrary signal then regenerate a new image with new timing that's compatible with (its understanding of) the attached LCD.
--There's no way to change the actual timing going to the display itself, except to set the configuration-jumpers to choose a different standard-resolution (which may be useful in some cases?). This *may* still be feasible as, from what I can tell, the converter-chip is configurable via flash-memory. Unfortunately, I can't find any detailed specs for it, and the company keeps 'em under lock-and-key.
Older thoughts:
This is kinda a strange venture, since I don't even have a cracked LCD. And, actually, on looking at some images of display-cracks, I'm surprised to see that many still work *below* the cracks (how're those signals still getting down there?!).
I guess it depends on the crack. For instance, I've seen one where the crack destroys the image on the right-side of the screen, but there's a column about 1/4th of the screen-width that appears completely unaffected. That would be perfect for a system like this, even with this VGA->LVDS converter, as it could likely be configured with a short horizontal active period, and an appropriately-lengthened horizontal front-porch. The screen itself probably couldn't be *cut*, since the circuitry is usually at the top, but the cracked part could easily be placed *behind* a main-display, exposing only the functional part. Or, possibly, the screen could be cut vertically, but the circuitry would have to be left intact... peeling the broken part off the flex-circuitry. Then again, backlighting gets complicated. Another case I never thought would work, but I've been proven wrong by images on ebay: a screen which is cracked at the *top* but still functions at the bottom (again, how are those signals still getting down to those pixels?!) In the case of my ($6!) VGA->LVDS converter, when you send an extraordinarily long vertical front-porch (subtracting that from the vertical-active area), the image is shifted to the bottom of the screen... again, perfect (minus the whole physical cutting of the display down to size). Unfortunately, since this converter shifts the usable portion to the bottom of the screen, this limits the ability to cut a display whose cracked pixels are at the bottom.
Whoops, cracked one...
Whelp, I managed to crack one, right near the bottom... pretty much the ideal-case for this venture. Unfortunately, this was also the *most-finicky* display in my collection. Even before I cracked it, it was unable to sync with anything except the ideal timing specifications... I wasn't able to get it working with the VGA->LVDS converter I'd ebayed, even before the crack. Further, it has actual circuitry down the side of the display, so the crack resulted in cracking those circuits as well. No-Go. But, as I stated before, there're plenty of images of displays with cracks that still work, and I've certainly seen displays *without* circuitry on the side, so I'm still keeping the prospect open.
Anyways, the point is, there're definitely a bunch of ways worthy of attempting to make use of cracked displays. with a bit of experimentation. Wee!