LCD panels

[jvisaria]

you will in about six months

[remp]

You guys have given up on using laptop LCD's way too early.

After much investigation I am firmly of the opinion that laptop LCD screens are indeed connected to the laptop motherboard by primarily an LVDS system. This is based on two main factors.

Is LVDS a workable system
Is it used by a lot of manufacturers.

(1) National semiconductors 1991 developement of fast serial transmision which was adopted as a method to reduce the number of wires connecting the LCD to the motherboard through the laptop hinge. Prior to National offering their system manufacturers used a number of systems including large and expensive triple screened cables passing through the laptop hinge.
Using either a costly cable or cheap semiconductor transmitter/receiver option with only 4 unscreened cable pairs to send the red/green/blue/clock to the LCD is a cost effective and sensible technical solution.

(2) National offered this option at very low royalty to others almost cost free. Several documents I have read indicate 80 percent of laptops use the National Semiconductor LVDS system.

My last drawing shows the basic system.

As you can see from the drawing I show two items missing. One is the LVDS transmitter which is normally incorporated into the laptop motherboard and hence not easily avaliable and secondly the bios needed to give timing details via the graphics section and on to the LCD.

These two problems slowed my research down quite considerably. I assumed that a laptop LCD would have its LVDS receiver already built into the LCD and if you read my posts you see how I arrived at confirming to a good level of probability that this is the case. This being the case all I needed was an LVDS transmitter. But not one from a laptop motherboard because it would be hard to extract as different laptop manufacturers would probably have different physical executions of the transmitter.

What really was needed was a separate LVDS transmitter.

Finally I found one at Advantech. From a link by Zardoz. LVDS transmitter receiver type PCM-3540R/T.
The transmitter is $80. Transmitting distance 2-5 meters.

Undoubtably the transmitter will be fed with cmos TTL so some way still has to be found to couple the TTL from your regular video card into the LVDS transmitter board.

The situation could be like this

A laptop LCD complete with LVDS receiver board
A LVDS transmitter board from Avantech

Leaving still to be done

How to connect the LVDS transmitter to your video card
How to control the bios.
How to connect power/bias to the laptop LCD

This is a step forward because only two items remain hopefully, one of which could be realatively simple that of connecting the TTL to the LVDS transmitter board and still leaving the unknown problem of bios signals. Providing power to the board is probably a relatively simple matter, but like all things needs some investigation.

Anyone wanting to look into this further look at some laptop LCD's. If a number show a 20 pin connector you can bet they are LVDS models with LVDS receiver built in.

There is a large document at www.eio.com which details exactly why it is impossible or expensive to connect a laptop LCD to a computer. Personnaly I think they are being a bit negative. Part of the fun of being a DIY person is taking an impossible situation and breaking it down into a number of sections each of which becomes easier to solve.

Those wishing to look further at LCD controllers here are a few links. Zardoz's link is the last one.

Google lcd controller

www.lcdcontrollerkits.netfirms.com
Model ACG-1024 70 UK pounds
www.electronicstalk.com/news/dig/dig102.html
www.mansky.co.uk/view-tek.htm
www.reachtech.com/display/analoglcd.html
www.sageinc.com
http://www.averlogic.com/LCD_controller/AL300.html
earthlcd.com/downloads/earthvid.pdf
http://www.horizontechnology.com/pro...er-boards.html
www.aurora.se/lcd/controllers/ac-1024v3.htm
www.amtex.com.au/display_pdf/P31.pdf
www.smartasic.com/PDF/SD1010pr.pdf
www.eetimes.com/sys/news/OEG19981209S0027
http://216.239.33.100/search?q=cache...n&ie=UTF-8</a>
www.lcdcontrollerkits.netfirms.com
http://130.236.229.26/?section=hard&project=vgalcd
www.ite.com.tw/productInfo/ProductLCD.html
http://earthlcd.com/controllers.htm.
www.adm-electronic.de/xga01.htm
www.digitalview.com

Sharp LQ6NC02 6" display.
Sold at Ebay October 2002 for $66 US
Text from Ebay seller
Surplus Sharp 6 inch active matrix TFT color LCD monitor. Accepts composite video (right out of your VCR, playstation, TV) as well as NTSC\PAL and some form of digital input (can use VGA output from your video card) Original intended use was for personal inflight audio\ video entertainment systems. Sticker with stylized logo on the back of the LCD says "GEC-Marconi Inflight Systems."
240(v) x 720(h) (Total 172,800 pixels) Delta Configuration.
Built in video interface circuit including chroma demodulator, picture tone, video AGC circuit and control circiut responsive to composite video.· Also responsive to standard analog RGB video signals

Links to many hardware/software controller info
www.panelsoft.com/uihwsw.htm
Description of National Semiconductor LVDS and RSDS
http://www.chipcenter.com/analog/pro...ves/prod28.htm
www.sensoray.com/html/322data.htm
www.adm-electronic.de/vga01.htm
www.asiabiztech.com/wcs/frm/ nea/200103/peri_124539.html

******************************
Google video lcd controller
www.gendig.com/products/monkit/oemmkov.htm
www.innovaelec.com/cps1000.htm
www.averlogic.com
www.eio.com/lcdconnect.htm
www.gendig.com/products/standalone/rgbindov.htm
fsc-pc.de/KnowHow_DriverCD/E/Produkte/ Mobile/Kompatib/Display.htm
www.smartasic.com/PDF/SD1010pr.pdf
www.spectrah.com/LD-S270.htm
http://www.winsystems.com/products/d...s/ppmfpvga.pdf
http://www.emacinc.com/pc_compatible...fo/pcm5864.htm
www.spectrah.com/arv-400.htm
www.electronicstalk.com/news/dig/dig000.html
www.siimage.com/products/display.asp
www.opencores.org/projects/vga_lcd
www.techwellinc.com/Products
www.horizontechnology.com/product_display.html
www.karbosguide.com/hardware/module7a6.htm

Zardoz link. Lvds transmitter/receiver boards
http://www.advantech.com/estore/prod...del_id=1-9B1ZR

[zardoz]

I agree remp! I think if we can get a lap top panel to work we will be able to do this project with some style. As I said I'm just a retired army mechanic turned computer tech....if you can give me a reasonable idea of what to look for I have nothing better to do with my time than to look.

have I posted this one yet? http://www.unigraf.fi/PAGES/testeq/viatmds.htm

Again to all concerned...if I post a dead end or one that has been explored and defeated just ignore it......ya never know I might just stumble on the answer for you. And if I do (find an answer) please let us all know.. cuz I might not recognize it

Zardoz

[Smoke Eater]

Thanks for going to all this trouble and effort, it is appreciated by those of us that can't or don't have the knowledge in the field. Nothing is really impossible...it may be impractical, or it may not be practical YET, but just think of all we can learn on the journey. I'm not much help with this part of things...but if you need something taken apart just let me know Thanks for sharing.

[remp]

Thanks for the thumbs up guys. The way I look at it, it certainly is a bit of a difficult problem but the laptop can communicate with its LCD so if we figure out how that happens we might be succesful.

I keep remembering what Stoko said and I hope he is right that you can get not bad LCD screens from broken laptops for a few dollars.

I should tell you guys I am no expert on this. Just another DIY person but I sure am interested if we can get a MUCH better LCD for not a lot of money

Smoke eater.
You took apart your laptop LCD didn't you. Could you do it again and see what sort of cable you got from the motherboard up to the LCD.

If it has an LVDS connector it should be a 20 pin. No other wires to the LCD apart from maybe a couple of wires for the backlight and maybe for power but its the 20 pin connector I am interested in.

Zardoz
You posted the link I was looking for about the Advantech PCM-3540r/t LVDS transmitter receiver. Good on you.

Anyone have access to several broken Laptops. Doesnt matter even if the screen is broken.

Zardoz maybe you could go around all the service depts in your area. See if you can pick up any broken laptops.

We need to be convinced the LVDS system is a goer. Since I do not have access to any in my area you might. Stoko gave a link to a video that shows how to take an LCD panel out of a laptop. I mentioned about it in my last or second last post. Have a look, shows you how to do it.

If you do get any, pull them apart and check the cable from motherboard to LCD. Should be a 20 pin connector.

I have not looked at your link yet but will do soon.

What I think is a reasonable way of investigation is to first read all I can about how laptops talk to the LCD. Done that and it seems the LVDS system is a very commonly used system. Next step is to see if that is true by sampling a few broken laptop LCD and see if they have the LVDS 20 pin connection.
If that turns out to be true, we have some good info on how the laptop communicates with the LCD. If we do actually get an LVDS lcd, and a transmitter from Advantech there is still the unsolved problem of connecting the transmitter to a PC video card and how to handle the BIOS.

So we are waiting now for confirmation that a good number of laptops use a 20 pin connector to connect to the laptop lcd.

[remp]

Originally posted by Zardoz

have I posted this one yet? http://www.unigraf.fi/PAGES/testeq/viatmds.htm

Dont think so.

It is a link to various test equipment for testing LCD panels in service shops/manufacture and research. Other video test gear available as well.

One of the features is it/they comes with a disk with various common LCD timing parameters supplied and one can edit and save these for non standard LCD's. Pretty useful. I think this test gear would not be cheap. If one was on Ebay for $5 snap it up.

[remp]

Could somebody who understands Russian please have a look at this link.

It shows a picture of a video card with some words in English. It seems to have the usual CRT monitor output and also a LVDS output. Maybe a list of outputs and if they mention a price in US dollars would be good. Looks like a PCI card. Thanks

www.icn.ru/i/a.nsf/nm/20-0/$FILE/icos_v20.pdf

[remp]

Google lvds lcd shows a number of interesting links.

This one

http://www.mite.cz/etxlvds-en/etxlvds-en.html

Shows a picture of a small computer board with an LVDS driver built in driving an LCD panel.

Note the connecting cable with a small number of wires.

This type of system from this company or similar is interesting. If it is cheap enough worth looking at because they may have bios settings for a number of different panels.

I cannot imagine one can get a small size computer board with a good quality video card at a low price. It may be possible but I dont know at present so I have been thinking someone must have a box that takes VGA from a pc and puts out LVDS for not too much money. The box should have the ability to configure for different panels. Using VGA from a PC is a backward step away from full digital but as an interum solution it is good enough.

The link is almost what we want but not quite.

[zardoz]

Just like a dog with a bone.....I dont know how to quit. I think this will help ...I'll get a price for it today.

http://www.spectrah.com/LD-S270.htm

(main product page http://www.spectrah.com/product.htm )

Zardoz

[Smoke Eater]

Remp, I still have mine apart, but just started a 24 hour shift at the fire station, I'll get home in the morning and get you the info about the ribbon. There is just one flat ribbon cable to the screen (not including the backlight connections), but I can't tell you for sure about the pin count until tomorrow. If need be, I'll take a photo of it and post it.