LCD panels

[Smoke Eater]

The local Office Depot's new advertisement has a MicroTek 15" lcd monitor with a resolution of 1024x768 XGA for sale for $279.99 (including rebates). My thought is, are lcd monitors coming down in price to where us trying to "piece" together receiver cards/lcd screens/etc.... isn't going to be worth the trouble? If they come down a little more, maybe it will just be better to buy the monitor and dismantle it to expose the lcd screen instead? I wonder what our "breakeven point" should be? If we can build one for less than say $150? Or if it takes us $200 to put one together, would it be worth a little extra to get the monitor? Just some questions on my mind.....

[moltenrock]

Hey Guys,

I was just wondering if anyone could help me out? I just recently acquired this panel from someone and it's just the bare panel with no backlight (pic). There is a long 30-pin ribbon cable coming off the side of the board connected to the panel, but I have no idea what I am supposed to connect this cable to. I even know all the pin-outs for the cable, but I still have no idea what I need to do to it so that I can enable it to play video. If anyone would be kind enough to help me out, I would greatly appreciate it!

Thanks!

[iilsley]

Is this panel worth looking @

http://www.overstock.com/cgi-bin/d2....&PROD_ID=48219

TM5800 5.8-inch Active Matrix LCD Monitor

Perfect for any portable display application, the TM5800 LCD monitor offers a high-resolution, full-color display. Use it with a portable DVD or VCD player for entertainment in your car. It's great for GPS applications. Save a bundle on this display today!

[Lifter]

SmokeEater - Personally I don't think it's worth it at this point. You could find a good deal and only have to spend $200 or so on the panel and all the parts to make it work. But why bother when prices are getting as low as $280? Making a bare LCD work on a PC is a serious pain in the *** and not worth $80. Just my opinion.

moltenrock - read my posts. All LCD models have different connecters with different pinouts. That 30 pin ribbon is useless because it was made for the motherboard of whatever laptop it came out of- and nothing else. Find where the ribbon connects to. Then you'll have to find a controller card and a custom cable that is made for that panel, or an board that converts it to analog VGA.

iisley - What makes you think that panel is high resolution? It's a video LCD that only has a composite input, so the highest resolution it'd be is 640x480, and I highly doubt it's even that high considering the fact that it's so small and meant for TV viewing. It's not a horrible deal for what it is, but I'm sure it's worthless for a projector.

[Lifter]

Originally posted by remp
stoko

Good link.

The whole problem with trying to even think about using surplus laptop LCd's because ebay is getting expensive is we have to try and figure out how they are connected to the laptop. What technology is involved and how it works and most importantly how can we identify panels that might be useful.

So far the only clue I have found is if the LCD has a 20 pin connector it's most likely using a LVDS connection system.

The LVDS system comes in two flavours

FPD-link for short links like inside a laptop
LDI for connection to a desktop mounted LCD.

The transmitter and receiver combinations are different for FPD-link and LDI link.

The max distance they say the FPD-link will go is from a laptop video card or motherboard to the hinge and then to the laptop LCD. They say 30 cm (12 inches).
Thats not a lot of use because for projection work you might have your computer several meters away from the LCD.

But I bet you could probably get away with 60cm (2 feet) specially on the lower resolution panels.

Still not really any good is it. You need at least 1 meter (3 feet) and 2 meter ( 6 feet ) would be better.

The options with laptop LCD's seem to be
(1) Find a LVDS LCD (20 pin connector)
(2) Find a video board that can fit close to the LCD that puts out LVDS
(3) Feed analogue into the board from either VGA, composite video or s-video.

Exactly similar to the controllers from Earthlink.

I have found several analogue boards around the $100 dollar mark. I have not yet investigated this in detail.

But now at least I know that no bare LCD panel takes in analogue, they are all digital.
Feeding them with digital is not easy
Digital would be best quality
Analogue is still ok for average use
Might be a lot easier to find an analogue board
Easier for cable length

Analogue or digital its still going to cost
The LCD panel
The controller

And if you buy an analogue controller from Earthlink or similar you have to specify the panel.

Another thing I have found out is specifying the panel does not seem all that difficult.

Assume the LVDS serial link is streaming red blue and green to the LCD. Starting at row one column one, for NTSC after 52 microseconds, the setup says hold the data steam because we now have a sync pulse. The data stream is halted for 12 micoseconds then resumes.
Meanwhile the row and column drivers have repositioned at row 2 column one all ready to start displaying the next line of data.

So what the BIOS function is doing is providing the sync pulse timing for NTSC or PAL or SECAM and the wait time between active display. These are very critical but its not hard to do.
I am not sure if its done at the transmitter end to halt data flow or at the LCD end under the Timing control IC but basically all it does is count clock pulses and knows when data should be displayed.

Also many video cards output one pixel per clock pulse or two pixels per clock pulse. The panel needs to know that information.

Also some video cards fill the frame buffer and wait until that is displayed before adding more info. Some video cards fill the frame buffer continously as fast as they can.
Thats another thing the panel needs to know.

So the bios tells the computer and LCD what to do and when to do it. Very similar to when you install a new printer or modem.

I will now start looking for an analogue board that can be fitted close to a LVDS laptop LCD and see how I get on.

Sorry I didn't read your posts before. Sounds like your doing the same exact research I did 3 years ago when I put an LCD screen in my car. Anyways remp, connecting a laptop display to a PC is not that difficult or expensive if you can find these 2 things: An analog controller, and a cable to connect that controller to the panel in question. Then all you need is VGA. I don't know why some many people here think using a laptop panel is a bad idea. As we've both stated, standard flat panel link is not supposed to work for more that a foot (although I got mine to work 8 feet away w/ a shielded cable). Don't worry about LVDS, Panellink, or DVI. I know DVI is tempting because major brand name graphics cards support it, but it's too much money and nobody will sell you a reciever board for it unless you order in bulk. And finding or making a custom cable to connect the reciever to the panel is also going to be extremely difficult. It is possible, but kind of pointless. You don't lose any noticable quality by coverting it to analog VGA. If your source is less than 8 feet away, get a shielded FPD cable from earthlcd.com like I did w/ my car. If you need to go further, just go the analog VGA route.

The real question is this. Can the back of a laptop LCD easily be removed to make it transparent? And if so, what kind of cooling is needed if it's sitting on top of an overhead projector?

[Smoke Eater]

Lifter: I've taken apart my toshiba laptop to expose the lcd screen (much to my spouse's dismay) and it actually came apart quite effortlessly. I probably had it apart and suitable for a projector application in less than 10 minutes (working carefully so as not to destroy a perfectly good laptop). I know its only one model and design, but I would imagine there can't be too many different designs of lcds for laptops? I could see one possible problem with using monitors instead of laptop lcds, though. Laptop's are made to be very "thin" through the lid/screen area so that the lid is not very bulky and heavy. They seemed to allow extra length ribbon connectors on mine to move the circuit boards to a more favorable place. The monitors that I have looked at seem to be thicker and I wonder if the parts are "stacked" a little more than the laptops resulting in shorter ribbons which would make it more difficult to move whatever boards there are out of the way. Has anyone out there dismantled one of the larger monitors?
I'm also interested in the analogue board route. Can a board like that be had for less than $100 or so? Is there a brand name to look for? (EDIT: Saw your other post about the kit)

[zardoz]

I have further identified my Sharp LM64C353, it is actually a Kyocera part number KCS6448JSTT X6. It has 31 pins on the connector, the backlight and related gear came off easily. The pinout diagram for the LCD shows 7 pins are ground...leaving 24 pins ... the same number of pins on a DVI-D video card connector. The screen has one pin as "no connect" so does the card. The trouble is the card pinout has terms like pin 9 TMDS data 1- .....the LCD doesnt Am I closer? or still just spinning wheels.....if so at least the LCD was cheap as dirt ~LOL~


Any pinout wizzards out there?

Zardoz

[Lifter]

Originally posted by zardoz
I have further identified my Sharp LM64C353, it is actually a Kyocera part number KCS6448JSTT X6. It has 31 pins on the connector, the backlight and related gear came off easily. The pinout diagram for the LCD shows 7 pins are ground...leaving 24 pins ... the same number of pins on a DVI-D video card connector. The screen has one pin as "no connect" so does the card. The trouble is the card pinout has terms like pin 9 TMDS data 1- .....the LCD doesnt Am I closer? or still just spinning wheels.....if so at least the LCD was cheap as dirt ~LOL~


Any pinout wizzards out there?

Zardoz

Arrrggghhh. I said this like three times already. Why don't you read some of my posts. Your panel, as is, will not plug into a DVI video card and work. End of story. No ifs ands or buts. Wonder why pinout signals are called different things on the DVI card and the LCD? Because they are different. TMDS are LVDS encoded digital signals for long distance applications. That's what DVI is fore. Panellink and LDI do the same thing as DVI, just different formats. DVI is the current accepted standard. But your LCD does not have a DVI reciever on it. Why? because your laptop's motherboard is only inches away from it. Your panel will only accept non-encoded digital video signals (r1,r2,b1,b2,g1,g2, v-sync, etc.). That's a wonderful coincidence that it has the same amount of pins, but my my keyboard connecter has the same amount of pins as an S-Video connecter. Doesn't mean I can use it to hook up a DVD player. Come to think of it, DVI connecters use 29 pins, not 24.

Now all this doesn't mean your panel is worthless, or that you can't get it to work with a PC. You just have to buy some extra hardware for it to work. You need one of three things:

1) A digital flat panel controller card. This is basically the same thing that's on your laptop motherboard, but in the form of a PCI card. They cost anywhere from $100-$300. These are not the same thing that's on ATI cards. No video cards that can be bought in a computer store will do what these things do. They are not meant to work for more than 18 inches away from the panel or so. I've gotten one to work 8 feet away using a shielded cable that I got from Earth LCD 3 years ago. Something to think about.

2) An analog flat panel controller board. This converts the flat panel signals into analog vga signals. This allows you to hook up the panel to any 15 pin VGA card. They too are in the $100-$300 range. This is the route I would go.

3) Buy a DVI reciever board and connect it to your panel. This will give you long distance w/o any signal degradation you'd get if you went route #2. However, if you have a TV tuner card, or a DVD decoder card that requires a VGA loop through, you're screwed. Also, I don't know where you can buy just one.

Now whichever of the 3 routes you choose, you still need an internal ribbon cable to connect the controller/board to the panel. This cable will have to be cutom made to match the pinouts from the controller/board to your specific panel. The one that came with the laptop will NOT work. Many times the seller of the controller/board will give you the cable you need if you give them the pinouts of you panel. Sometimes, they'll have a list of "supported panels", and if your is one of them, you just tell them that and they'll have a cable already made for it. Many of these companies do not sell individual units to end users. They don't list their prices either, and you have to fill out a form for a quote. They're trying to land contracts from companies who make desktop LCD monitors. Earth LCD is the only place I know of that is completely made for end users. They'll make any cable you want for any panel they can get the pinout for. They sell digital and analog controllers, but they do not, however, sell DVI reciever boards as of yet.

[stoko]

if anyone is still interested in this, read this pdf:

http://www.conexant.com/servlets/Dow...pdf?FileId=325

it is datasheet about conexant bt868 tv encoder!
that chip takes the same signal from the board as the signal that is needed for LCD (3x6 or 3x8 bits of RGB etc.)!
so, i think that you could hook up LCD to any video card that has such or similar chip!

[zardoz]

Lifter...thanks so much for clearing up my obvious error in assuming that I may at some point in time or another stumble across a reasonable sollution to this project. And by all means thank you for stopping me from plugging my keyboard into my S video port. WHEW! that was a close one

I would like to point out that DVI-D has indeed 24 pins (even if it wont work) http://www.ati.com/support/connector...sfordvi-d.html

You are correct though DVI-I has 29 pins http://www.ati.com/support/connector...sfordvi-i.html

I do however thank you for your explanation of the sollutions you have found, once I waded through the sarcasm I did in fact learn a thing or two.

It seems that the multitude of hours I have available havent yet educated me sufficiently to the task at hand. So that being said I think I'll abandon the laptop screen idea (for now) as I am a technician... not an electronic's engineer.

.....do we have any people here with a degree in electronics?

Zardoz