Making Use Of Old LCDs?

phorm writes "Not so long ago, higher-definition LCD's used to be quite hard to come by, with laptops and other hardware tending to use old non-TFT-style LCD's which ugly bleeding colors and poor refresh. Nowadays, almost everything has a nice TFT (Thin-film-transistor) display, including laptops, PDA's, digital camera, and often even cellphones. However, not all of these devices are as dependable as they once were, and many of them end up as little more than paperweights. With TFT-LCD's by themselves still being somewhat of a pricey commodity, is there any way to salvage and use these parts for home projects? I personally have an 8" notebook display, and a 1.5" digital camera LCD which are just begging to be recycled as something useful such as a projector component, status display, or something else useful. So far I've had little luck discovering a way to get these components to work outside of the original hardware, so I was wondering if any enterprising hardware-nerds on Slashdot have had better luck than I and could offer a few pointers. Are these components doomed to end up in a landfill, or can somebody offer a way to make them useful again?"

Comments

You could build a video projector

[Clockwork Apple]

Just hit google up about "DIY Video Projection".

Re:You could build a video projector

[Phreakiture]

NTSC is the equiv of 320x240 at 30fps

Almost right. The part you were closest on was 30fps (actually 29.97), which is close enough. The X resolution varies, but in most circumstances is somewhere around 300, so you are right there, too. The Y resolution is 480, which is double what you were saying.

The X resolution depends on what your transmission medium is. Basic, composit NTSC requires that all of the luma information be lower in frequency than the 3.58MHz Croma subcarrier. This subcarrier is going to have a content bandwidth of about 1/2 the Luma data, and therefore a physical bandwidth equal to the luma data. Half that bandwidth will be below the subcarrier, the other half above, so we can assume that the space below the 3.58 carrier is 1/3 croma, 2/3 luma.

Since luma defines the basic resolution, this puts our dot clock at a maximum of about 2.4MHz. Not a lot, granted. If we keep it simple, and divide this by the 262 lines per field (remember, this is an interlaced image) and 59.94 fields per second, we get only about 152 waves per line, or 305 pixels.

There are special cases, however, that need to be noted.

If the signal is sent such that the luma and croma data don't intermingle (S-Video), then the X resoltion can go very high indeed. In fact, there is no real limit here. A 720x480 image is not at all out of the question, with the simple understanding that the croma resolution is going to be only 150 pixels or so, because the croma data are still carried on a 3.58MHz subcarrier (although all of the bandwidth is available, not necessarily constrained by the need not to collide with the luma or audio carriers.... whether or not it is used is another matter). DTV at standard definition, digital cable, digital satellite and DVD all bring us this.

Lastly, component video takes the gloves off. Since we are no longer modulating our croma data, instead sending it as its original two components (Pb and Pr), they, too, can be run at any resolution. Fact is, they are usually run at 1/2 to 1/4 the resolution of the Luma (Y) data, but they don't necessarily need to be. The reason they usually are is that DV and MPEG don't record the croma data at full resolution.

Of course, component video has the additional advantage of being able to support other resolutions. Composite and S-video can not do this because they depend on a fixed-frequency croma carrier.

LCDs are difficult

[Anonymous Coward]

Laptop LCDS are a pain to work with. They are just the screen themselves and the rest of the controllers and hardware is usually built into the video card or laptop motherboard and is useless outside that.

You can get controllers for many laptop screens, however they only work with specific screens. Say maybe 2-8 out of 300 can work with a particular controller. Most controllers need to have their BIOS programmed and that's usually done out of the factory for specific applications.

On top of that you need to supply your own inverter, any special or propriatory cables or connectors, a power supply, and housing.

This is doable, but expensive.

99% of the time you'd get a better, cheaper, newer LCD display somewere else then trying to build a display out of some random LCD screen.

Better off getting a retail version, or buying a kit from a place like EarthLCD.

Finding specifications

[timecop]

Is going to be your biggest problem. I've had some EPSON-made TFT lcds from cellphones that even epson refused to give me datasheets to - most cellphone LCDs are custom jobs for each specific manufacturer, and they will not be telling you any information about them.

You are better off trashing the screens you got and ordering some cheap LCDs from a place like http://www.mp3playerstore.com/stuff_you_need/speci al/index.html and connecting it to your car mp3/dvd/player whatever.

Difficult, but possible

[Kalewa]

Case modders have been trying to do it with laptop displays for awhile now. The general consensus is that it's more trouble/money than it's worth.

Check here for some LCD controllers and tips on how to put it together. The problem is that the controllers often cost as much or more than a cheap LCD by itself.

Save the lamp!

[ValourX]

Save the screens for the CCFL lamps that illuminate them. That way when you have to replace such a tube when it wears out or breaks in your working replacement device, you will have a means of repairing it.

CCFL (cold cathod fluorescent lamps) have a life of anywhere between 15,000 and 50,000 hours and most will lose half of their brightness after roughly half of its lifespan. They're also made of thin glass and are easily broken. If you break a CCFL tube you will probably not be able to buy a replacement and even though the tube only costs a few dollars you will have to replace the entire LCD screen at a cost of hundreds of dollars (in a laptop system).

So yeah, keep them for parts... mainly the lamp.

-Jem

Re:Save the lamp!

[Lumpy]

allelectronics.com

they usually have lots of CCFL tubes in different sizes...

those parts are EASY to find if you know where and what to look for.

Re:LCD Wiring

[cybermace5]

That is not what the submitter was looking for. The HD44780 interface is old as dirt and very well known; there are lots of programs available for practically every computer, operating system, and microcontroller in existence, in every language that each of the preceding platforms support.

The real question, interfacing TFT displays, is a wild goose chase. Without the datasheets, an appropriate controller chip, and a good understanding of how to get configurations into said chip, you're not going to get it to work. Some converter boards do exist, but they cost a couple hundred dollars and support only a few LCD panels.

Your best bet at using a given LCD panel is to find the part number, then try to locate a single-board computer that has a personality module for it. This still isn't going to be a cheap solution.

My preferred use: neat pressure-sensitive coaster.

Link...

[jg_elliott]

This site has the answer to connecting a laptop monitor to your pc.
http://www.eio.com/lcdconnect.htm
google cache: href=http://www.google.co.uk/search?q=cache:Ily0Qs g_-twJ:www.eio.com/lcdconnect.htm+site:eio.com+lcd connect&hl=en&ie=UTF-8

It's not been updated in a while, but the summary goes: You need to buy a controller, the one that came with the device won't do. They cost more than an lcd screen itself, so unless you're desperate to recycle, you might as well buy.
As for ideas what to do; I always thought i'd be cool to have a little display of system statistics cpu/ram/disk usage, maybe any new emails that have arrived - basically most of the features that superkaramba gives you, except you'd be able to see it when running full screen apps.

Good Luck.

[Rolo Tomasi]

Driving LCDs without inbuilt controllers (i.e. the ones you find in laptops and other digital appliances) is non-trivial. The problem is, you need some kind of controller, and then you also need to drive that controller (preferably over a CPU bus or some other fast connection). Epson makes LCD controllers. You'd have to design a PCB and then solder an SMD chip with hundreds of tiny leads (or even a BGA chip). The other alternative would be to brew your own controller with an FPGA, like this guy did (text is in German). He built a controller for an old 640x480 laptop TFT.

Basically, without some rather advanced electronics skills, you're SOL.

Oh, and don't just hook up a display's power without providing the proper clock signals ... the liquid crystals will decompose through electrolysis.

Blame the industry

[ajlitt]

There's no real standard for LCD modules, even the PC variety. When designing an LCD into a system, one first needs the appropriate data sheet, which is usually hard to come by (requiring a phone call to a MFR rep or such) and ill-written. Then, you need to provide the appropriate voltage rails, many of which fall outside of the range of a normal PC supply (bias, contrast voltages). And that's not to mention the (often) high voltage backlight!

Once you've sorted all of that out and your LCD powers up, you will need to interface your video signal. There are not only many different physical connector schemes used in panels, but many pinouts and electrical / timing methods. Not to mention that the panel takes a serial or framed digital signal, while your PC probably emits an analog one (except DVI-D)

Once your panel is lashed up to a host, you would need to convince your OS to drive the panel with a VERY specific set of timings. Remember, this panel is a purely digital device and isn't tolerant of sloppy video or sync signals like the average glass boob is. And of course forget about baseband TV video unless you're prepared to do some scan conversion.

You could make it work. I occasionally have to spec and implement LCDs for projects at work. It's not easy to do even when you have a device designed to drive an LCD. Hell, some of the VIA Mini-ITX boards come with a LVD video output port for driving some panels. But still, you can see that there is more value in that flat panel monitor than just the LCD.

Datasheets galore

[kryoptic]

This site http://www.eio.com/datashet.htm has a bunch of datasheets for various LCD screens. From what I can gather it's terribly difficult to make use of an old LCD screen. They're not directly compatible with standard vga. You must have a controller.

Here's a link, try not to kill yourself

[FigWig]

Linky linky

even more links/ideas

[cwg_at_opc]

i've been researching this for a while; below is what i've got bookmarked. a vast number of LCDs only have NTSC input,
so those might not be so hot unless you've got TV/NTSC out on your video card. LCDs with VGA controllers can be
found but are much more expensive. many vendors prefer to deal in volume only, so don't expect
too much help, or fast email replies.

i'd have to agree with some of the other posters; you might want to get an old thinkpad and butcher it a bit if you need
to get more resolution than TV(less than 640x480 IIRC, maybe 425?)
anyway, here are some other novel uses:

1 - get a bunch and make a shutter for a window in a car, sunroom, etc.
2 - get a bunch and make Art, i.e. a large random color/shape thingy to hang on a wall
3 - use it as a shutter in your front door for inspecting IDs
4 - use one as a digital shutter for a darkroom enlarger(for those still using film, that is.)
5 - make your own car/truck rear-view screen(needs a vid-cam)

OCH LCD MicroView Review

LCD Mod

Extreme Overclocking-5in LCD Ultra-Thin Video Module Review - Page: 4 - Tweaking PC Hardware To The Max

Mikhailtech

5 Color LCD Mod

Mini LCD Monitor Review - Amdmb.com

Computer Compatible Small Format LCD Monitors

EarthLCD Home Page

Candescent: ThinCRT Showcase

Caltron Industries, Inc.

Caltron Industries, Inc.

Timeline, Inc. LCD Displays

6a3 5 X-Bri PAL-NTSC

6 TFT LCD Module Kits

5 mobile lcd display

Mobile LCD Modules

Pyle PLVWHR56M<br>5.6 Mobile Video LCD Monitor<br><img>

Parts Express: Browsing LCD 4 VIDEO MODULE

LCD Projectors, LCD, LCD Monitors, LCD Displays, LCD Panels, LCD Screens, Small LCD Monitors, LCD Flat Panel Displays, Resistive LCD Touch Screens

flat panel displays from Spire Controls

Controllers are NOT unobtanium

[poptones]

Yeesh. Controllers are NOT so freaking hard. They're also NOT "about $400" as one know it all stated, nor are their specs such freakishly closely guarded secrets. In fact, if you are capable of soounding at all like you know what you're talking about you can get a couple of samples for the asking. And who do you ask? Well, Analog Devices is a good start - they have about a dozen different types.

Yes, it would take some time. Yes, it would be a challenge. But it's a long way from impossible, and all it takes is a handfull of off the shelf parts - AD even has application notes. Combine one of their evalkits with the specs for, say, an IBM TFT display (13.3" 1024x768 units are like 80 bucks on ebay and 14" 1280x1024 units are only slightly more) and I''ll wager you could not only make your own display circuit, you could probably offer the pcboards after you design it and make enough money to buy a proper projection hdtv.

Let us know when you have the circuit - I want about four of'em.

Thanks

[Matrix2110]

...Actually, since it's an analogue signal...

Thanks for setting him straight, I was looking at his post wondering what planet he was from.

You should have also included the fact that interlacing is an accepted (evil?) on the analog world and is still a big thorn in the digital community. That little "i" or "p" in those resolution numbers is a big trade off. Computer monitors use progressive scanning almost always, and that is the way it should be.

Television has fought so many format wars that the battle lines are still being drawn. For example this week they are holding NAB (National Association of Broadcasters) in Las Vegas.

Every single inch of convention space is taken up by the broadcast divisions of the big companys and the 'mom and pop' vendors all competing for your attention for five solid days.

Now I am rambling but I will leave you with this: The Las Vegas hotels hate this convention with a passion. Because the entire thing is populated by people that are so smart that they know the odds inside and out.

Re:Way to make them useful again

[BrianRaker]

You might want to check out EarthLCD. They carry a good number of parts for making LCD panels usable outside their original housings and configurations.