LCD Panel to PC interface project

A lot of people seen to think that they can easily interface a laptop monitor to their PC.  While it is possible, most people don't have a clue what's involved.  While some LCD panels have built-in controller, most, including ALL laptop displays DO NOT.  There are no smarts on the LCD panel at all, just row and column drivers.

Many of the links to the EIO pages are broken. I'm going to leave them up for a while, but, if they don't return I'm going to delete them from this page. They have done a lot of updating to their site which is now at www.shopeio.com. It doesn't look like any of their forums made it to the new domain.

You might want to read this web page on the EIO web site.  www.eio.com/lcdconnect.htm
It is a collection of posts to the EIO LCD forum on the subject of using laptop LCD panels as a monitor for video or VGA.  Some of the posts were made by myself and some were posted by other knowledgable people who want to help keep the forum going.  You might also want to read DJ's post the the EIO LCD forum.  Here's another informative post by DJ.

Below is a picture of a LCD controller based on the Sage Inc. Cheetah4 chipset.  Sage Inc. was bought out a while ago.  They are now part of Genesis.  The bottom right corner is the on board power supply.  It takes +12V in and generates +3.3V and +5V.  In the bottom left is a daughter board for input interface.  This particular daughter card is for DFP (Digital Flat Panel).  DFP is an earlier version of what we now know as DVI.  Only the connector has changed.  DFP and DVI share the same TMDS signalling.  DFP was only capable of single link which limited its resolution, that's why DVI was developed.  DVI uses a connector with more pins to accomodate two TMDS links as well as analog VGA.  The daughter card in the upper right corner is the panel interface adapter board.  There are lots of different LCD panels out there and there LOTS of different interfaces.  This board provides three output connectors.  I'm using connector #1 & #2 for my Mitsubishi panel.  In the upper left are two chips with stickers on them.  The upper one is an 8 bit microcontroller (80C32) and the chip directly below it is the program code storage flash memory for the microcontroller.  The code that is currently in the flash memory is specific to the LCD panel that is connected.  If I were to change to a different panel the code would most likely need to change as well.  This code change would need to be made by the controller board manufacturer.  The microcontroller basically writes parameters into the Sage controller chip to configure it for the LCD Panel (H/V resolution, H/V refresh timing and blanking, etc.)  The cable coming off the left hand side of the board supplies power to the CCFL backlight inverter.

The picture below is another panel adapter board.  The pinout off the first panel adapter daughter card only got me close.  This second board got me to the point where I can use flat flex cables directly to the panel without doing any fancy wiring.  The pins on most LCD panels are very close together and soldering to them would be very difficult.  Having a board that maps the signals to the proper connector so that standard flat flex cable can be used is a must.  You can see in the last picture that from the second board it's a simple connection to the panel.  I think one of the cables is 30 lines and the other one is 40 lines for a total of 70 connections to the LCD panel.  Most of these are ground with a good number for power and about 27 for the LCD signals.

The picture below is of the entire design.  Here you can see the LCD controller (bottom left), interface board (bottom right), LCD panel input connector, CCFL backlight inverter (top left).





Where to buy panels
eBay
Asia Tech
LCD-r-Us

Ok, already have a panel, now where do I get a controller. <Click Here>
Need data sheets for a Sharp LCD Panel.  Find out how to get them here.

FAQ:
Q:  Can I take the video controller out of the laptop that I got my LCD from?
A:  No.  The video controller is usually on the main board and even if it isn't the interface to the board will be PCI or AGP, but, not with the PCI or AGP connectors that we are familar with.  About the only pieces of any value from the old laptop is the display cable and maybe the inverter board for the CCFL backlight lamps.

Q:  Can I connect the LCD display from my old laptop directly to my PCs video card?
A:  In 99.99% of the cases, the answer is no.  There are an incredibly small number of PC video cards that can directly communicate with LCD panels.  They are typically made for industrial PC applications and are PC104 card based.

Q:  Ok, I have a controller.  Can I just connect it up and expect it to work?
A:  No, the controller will have a program memory chip or BIOS on it that needs to be configured for the panels timing specifications.  Things like resolution, timing and scanning type all need to match LCD panel connected.  Don't believe me.  The following is from the Octagon web site.  Octagon is a maker of industrial PC and single board computer that can interface to many LCD, Plasma and EL flat panels.  If your panel is not listed:
Octagon's SVGA cards can drive CRT monitors at super VGA resolutions and most flat panel displays in existence.  There is no standard interface to the numerous types and brands of flat panels available.  This means that a unique video BIOS needs to be generated and programmed into the card and a special cable needs to be made for each type of panel.  ...  Customers can easily interface to any of the panels listed.  Octagon makes an attempt to keep this list updated, however new panels are continually being developed.  Contact an Octagon Sales Support Engineer if your panel is not listed.  If you want to use a flat panel that is not currently supported you will need to provide Octagon with the data sheet on the desired panel.  If we approve your panel for development you will need to send the panel and documentation with all cables, connectors and inverters to us so that we can create the video BIOS file and generate an interface diagram.  There will be a one–time charge of $750.00 for this service (allow up to 4 weeks).
Taken from the following web page http://www.octagonsystems.com/AccesPages/fp500-510.html
 

Tips:

Web page created by Scott Johnson
Please send any corrections to p9019@yahoo.com
Do not send me questions!  Questions should be posted on the EIO LCD Forum.  Don't forget to check their current LCD offerings.


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