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Hardware

Reusing Laptop LCDs for DIY Projects? 36

Posted by Cliff from the LCD-deja-vu dept.
eaddict asks: "I have just purchased over 20 older laptops. These laptops are old Toshiba Satellite CS110, Acer 350P, and IBM Thinkpad 365Xs. Most have bad floppies, damaged cases, and no battery. When I power them up all the displays look decent. So now I wanna hack and play. I am trying to figure our how to reuse the laptop screens so I can use them to build things like: a combined larger display, an automobile display for a DVD player, photo frames, and other nifty ideas." This question is a replay from about 2 years ago. What hardware will you need to drive a single screen (once it's been severed from the laptop corpse), or a group of them, as mentioned above?
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Reusing Laptop LCDs for DIY Projects? More

Reusing Laptop LCDs for DIY Projects?

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  • Find a way to get a network connection to all of them and run a (custom?) version of VNC on all of them.

  • Simple DIY VGA-LCD converter (Score:5, Informative)

    by cyr ( 571397 ) on Tuesday May 21, 2002 @07:18AM (#3557205) Homepage
    Right here [130.236.229.26].

    This version is only good enough for 8-color text mode, and only works with TFT displays.

    LCD (TFT) panels aren't really that different from normal VGA monitors, the R,G,B signals are n-bit digital rather than analog and you need to supply a pixel clock... that pixel clock should be derived from the video signal using a PLL, but this simple circuit uses a fixed crystal oscillator instead because I had one handy. I'll post an improved circuit at a later date.

    To turn the panel into a digital photo frame you could probably use a Flash ROM (and a RAM if the ROM is too slow to read out at the correct pixel rate), and some basic digital electronics (either a bunch of discrete counters etc, or a CPLD).
    • Interesting... I think you're the first person I've seen to actually try it!

      Although you do have to admit that to run a LCD panel with scaling for other resolutions and with proper synchronising would require a much more complex circuit. Most of the cards out there to drive a LCD display seem to be a laptop LCD display chip stuck onto a PCI/ISA card with a hefty markup.

      As the inverters introduce a slight propagation delay the HSync and VSync pulses won't be exactly in sync with the RGB data. Wouldn't delaying those lines slightly improve the picture quality?
      • Well, it's mostly a "proof-of-concept" kind of thing... I wanted to see if it was possible to do with such a simple circuit. Being able to support (scale) different resolutions would be a *lot* more difficult, but that may not be a problem depending on what you wish to do.

        The propagation delay isn't much of a problem, at least not compared to the jitter caused by having a fixed clock that isn't exactly matched to the VGA card pixel clock.

        I plan an improved version using a PLL for the clock, proper (adjustable) centering of the image and maybe "real" ADCs for full color (maybe some free samples from Maxim...).

    • LCD (TFT) panels aren't really that different from normal VGA monitors, the R,G,B signals are n-bit digital rather than analog and you need to supply a pixel clock...

      Depends entirely on the display. I have some Sharp TFT LCDs which came from NEC laptops and they all use LVDS signalling to get the data across so the circuit you present won't even come close to working. You need to take the analog out data, convert it to digital (quickly), send it over via LVDS and hope that everything comes up normally on the other side. Actually this sounds like a fun project, something to work on my analog skills with. :-)

      The better thing to do would probably be just to use the DVI port on a Radeon VE or use the Feature Connector on most ATI cards; it would save a lot of work. :-)

      • Well, I should have added for *old* displays... like the 640x480 panels found in 486 class laptops. At least the VGA/SVGA panels I found datasheets for...

        I'm not familiar with LVDS, but the principle remains the same right?
    • The keyword in his question was SIMPLE Projects with laptop LCDs. Please keep the post more like, LCD make great frisbees or can you a imgaine a beowulfe cluster of these?

  • The whole is more than the sum of the parts (Score:4, Informative)

    by Brento ( 26177 ) <brento.brentozar@com> on Tuesday May 21, 2002 @07:42AM (#3557262) Homepage
    When I power them up all the displays look decent....so I can use them to build things like: a combined larger display, an automobile display for a DVD player, photo frames,

    Instead of figuring out how to reuse just the displays, I'd suggest that you're probably much better off trying to figure out how to reuse the entire machine elegantly. For example, in automotive applications, old laptops are great because they're small, they use DC power, and they have a lot of niceties like PCMCIA slots (great for wireless modems).

    Photo frames are another good example - you can build a table with the laptop guts mounted underneath and the flat panel displayed under the glass top. Pick up a couple of cheap wireless network cards, and presto, you've got a network of photo frames that can be automatically refreshed remotely.

    Trying to reuse a bunch of different LCD's is going to be a really tough road. If you bought a set of identical ones, at least you wouldn't be doing so much research, but if you keep the machines intact then you're well on your way to finishing cooler projects faster.

  • Check out Earth LCD (Score:3, Informative)

    by djweis ( 4792 ) on Tuesday May 21, 2002 @07:52AM (#3557288) Homepage
    Their site is at www.earthlcd.com [earthlcd.com]. They have quite a few panels and the requisite converters for them. I've never bought anything from them but they have some cool stuff.
    • I actually bought 2 LCD's from Earth. The tech support isn't the greatest; but the new EarthVision 2 controller card is great. On-Screen controls, Auto-scan, etc. I put a 6.5" in my dashpc [dashpc.com] and the other is just a toy. I'll probably mount it on the wall or something. For a (vga) LCD you'll need:
      • LCD (duh)
      • controller (either PCI card or inline vga "analog" converter)
      • inverter - converts DC to AC for the BACKLIGHT
      If the LCD's are relatively new, they will probably work with the Earthvision controller. Your best bet would probably be to get in touch with Earth and see if they can help you out.

  • It may be easier with newer laptops (Score:4, Informative)

    by inkfox ( 580440 ) on Tuesday May 21, 2002 @08:30AM (#3557415) Homepage
    Many newer laptops have non-integrated video controllers on a "mini PCI" bus, which is electrically identical to real PCI, only with a different connector. In these cases, the display will be connected directly to the card with some sort of ribbon cable or simple harness.

    You should be able to use this with a standard PC by creating a PC to mini-PCI bridge. Prepare to do lots and lots of soldering.

    For any working laptops, I'd rather grab the whole thing and just run an extra X server on 'em though. Let it display a few extra apps for you, and go ahead and use samba to use the drive as a safe place for quick data backups. Pretty cool, and a hell of a lot less work! :)

  • I'm afraid it's just not that easy. I wish it were.

    I have a Toshiba 305CDS with a toasted screen (thanks, USPS-- your insurance is worthless!!!). It's running as a wireless router at the moment, but it would be nice to fix it. Are any of your's compatible with mine, I wonder...

    Anyway... Ideally, I think I would rip off the head/screen unit and get a little LCD from earthlcd and mount on the dash for my GPS/mp3 player.

    Then the real question is-- in the wife's car or dare I cut and slash my pure ride? :-)

  • I'm in the same boat as you, and it's mostly impossible. These things always need custom lcd driver chips, which you presumably have, but even if you use the heat gun to remove them, you'll never find the data sheets.

    I'd tell you to grab a few cheapies off of earthlcd.com, but even there you have to be careful.. they're usually discontinued, and sometimes you can't find chips or datasheets for those either.

    • Re:Don't bother.. (Score:3, Interesting)

      by Chanc_Gorkon ( 94133 )
      But it's NOT impossible. Here [ashleypowers.com] is a link about a guy who used a LCD from a old NEC Pentium 75 laptop. Sure, it not the easiest thing and for most of us it would take lots of time most of use don't have. But you should not discourage him. Check out the main page belonging to the guy who figured this one out and check out the PC installed in his Z! Out standing! Chek it out at this [ashleypowers.com] website.
  • Color LCD displays aren't cheap. the apple IIIe had an option for a 11" B&grey(W) lcd display, that looked suspiciously like that of a graphing calculator's, but uch larger. i've been looking for somthing similar, sothing htat will take a vga signal and display it on about a 14" B&W LCD screen. in theroy, this should be extremely cheap ($100) and easy to come by.... so far the closest i've come is those 2x40 character LCD's for cash registers and whatnot. any ideas?

  • Wow! Synchronicity or what? (Score:3, Interesting)

    by Anonymous Coward on Thursday May 23, 2002 @09:27AM (#3571855)
    I've always found it amazing that stuff I embark on seems to be just on the edge of being done by other people. Here's my story.

    I picked up a 3M 6150 LCD Projector Panel at a computer junk store. This is a 10" TFT panel with no backlight that is used on top of an overhead projector. Of course, this was built 5-7 years ago, and they have now been replaced by stand alone units. That's why I got it for 10$ cdn!

    It was very difficult finding information on this unit (go ahead try it), it has a 26 pin high density connector for the video in. I couldn't even find a mating connector for it. Anyways I built one out of a 'joystick' DB-15 hood and a high density DB-15 male connector. Then I saw an old monitor in the garbage and I cut off its video cable. Once I figured out the pinout it was easy to make a cable that plugs into the 6150.

    Then I bought a smashed Dell laptop screen and took the backlight out, 5$. Figured out its pinout and it lights up very well. Luckily, it was set to a pretty good brightness before it was turned off. There's an epot on the inverter board that sets feedback to the ballast controller, it needs I2C to work, I think I'll just remove the chip and replace it with a pot, since I'll probably never get the 6150's CPU to send I2C signals to the epot. (80188 anyone? I don't have tools for that)

    So anyways, I take the mounting hardware for the panel out, flip it around and chop it up a bit, as luck would have it, the backlight just fits in the new mounting space.

    For 15$ I get a 640x480 18 bit TFT panel. (I know, 3M claims it's 24 bit, but that's a white lie, the input is 24 bit, but the panel is 18 bit). What's the use? Well, a Commodore 64 looks decent on it after going through a scan rate converter (the 6150 takes CGA, but I still need RGB signals), and a PC at 800x600 gets 'scaled', but with older anti-aliasing, not sub-pixel rendering techniques. It's still legible.

    NOW for the laptop panel as monitor issue. I've traced the evolution of LDI and DVI. It seems National were first at proposing and implementing a LVDS scheme for laptops. (http://www.national.com/appinfo/lvds/)

    OpenLDI was used for the SGI1600SW 1600x1024 panel (I bought a "panel only" from eBay for 50$ US, but no casing, and it was reverse polarised, so the little control board is burnt) unfortunately, this standard never caught on, so finding a PC video card that supports this is hard and expensive. Search eBay for 'revolution iv' or 3dlabs oxygen vr1-1600sw and check out the INSANE prices!

    DVI uses a fundamentally different encoding scheme, although the physical link is LVDS, it uses different bit encoding and clocking. SGI made an adapter (http://www.sgi.com/peripherals/displays/multilink / ) but L@@K on eBay and look at the outrageous prices!

    This (http://www.dpie.com/pcbus/crtlcd1.html) seems useful, but I have yet to receive an answer to my queries.

    For the DVI specs, go to http://www.ddwg.org/

    The problem in getting a DVI to LDI link working is the dual pixel mode, at some resolution, DVI uses TWO sets of links to send even/odd pixels to the panel's TCON (Timing controller). Of course, LDI switches at a different resolution. I think that getting a 800x600 or 1024x768 panel working in single pixel DVI to LDI *might* be easy to do, you only need to receive the DVI signal and connect the output to a LVDS transmitter.

    Anyways, I wish I had a Web page to show you my 6150 and the SGI panel I'm working on.

    If anyone is out there, let me know what you're up to, I'll set up a hotmail address, I'd like to hear more!!

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