Internal LVDS Connectors

[James.]

I apologize if I missed something in reading over the LCD and case modding FAQ's, but I was hoping someone with more knowledge than myself could point me in the right direction.

About 6 months ago I finished my first MiniITX based computer. I use it as a home DNS server, sFTP port, etc. I run it off of a CF card to keep power requirements down, using an IDE/CF adapter. I noticed an interesting thing about the motherboard, it supports an optional LVDS module. I know that LVDS is an option for external displays, as well as one of the wiring options that can be used in Laptop displays.

What my next project with the miniITX form factor is going to be is hopefully my ideal wireless device. I work for a cell phone company, and I like the products they offer for wireless data. What I hate is not having a decent sized keyboard to type on. As well as the format of most mobile device screens is portrait not landscape.

The final device will hopefully be basically a "hacker's keyboard" with an extended casing on it to house the motherboard, CF Card, and battery. Attached to that, in a sort of horror show version of a laptop, a 7" LCD. (Approximately 2" thick and the size of the keyboard in other dimensions, excluding the attached LCD).

The Format I've been looking at most often is 800x480 widescreen 7" LCDs. The only problem that I've found is that none of these are "bare" LCD's, they are all in casings for attachment to a regular case. I am looking for a bare LCD with LVDS connections, and hopefully an LVDS cable to connect it to the motherboard.

Can anyone point me in the right direction for something like this? Or even a site for modding a standard external display to LVDS internal connectors would be great.

Sorry if I am rambling, I'm heading to work right now. Please let me know if you need any more information and/or specifications to clarify what I'm looking for.

Specs of the hopeful project:

802.11g/b support
EDGE/UMTS support via PCMCIA cards
Bluetooth
IR
2GB CF card, possibly 4GB if they come down in price soon.
1GB memory
integrated graphics
Linux OS
Battery life exponetially better than a standard laptop, since there are no moving parts. CF cards draw approx .5w of power, even a 5400rpm drive draws 15w.

If this is in the wrong forum, plese move it. I apologize.

 

[xonik]

Finding someone who will ship a single unit that meets the 7", 800x480 requirement and features only the LVDS bus interface is going to be a difficult and expensive venture. You're better off stripping down a "mobile video" 7-inch unit down to the bare LCD.

From my dealings during my laptop LCD to PC monitor conversion, I have found that certain segments of the flat panel business are locked up tight. Semiconductor manufacturers in general don't like small-quantity customers like you and me who just buy a single unit--I'm sure you know the reasons. No one is going to want to sell you a bare 7" flat panel that is brand new and has all of the documentation you'll undoubtedly need for that digital input. Now, a replacement laptop screen--that's another story. With eBay, you might find a suitable LCD, but not necessarily the documentation.

Now, the LVDS scheme. I am not in the flat panel industry, but I can say for certain that not all LVDS schemes are created equally, just like TTL signalling schemes. You can't just plug in any LCD with LVDS support into an LVDS output connector block, pinouts aside. There is 5 volt LVDS, 3.3 volt LVDS, maybe lower than that--I don't know, but you should before you plug anything in. Also, the LVDS transmitter must understand the signalling characteristics and patterns that any given LCD is looking for. It's a complicated process...

And that's why I say you should buy a "mobile video" LCD. That way, you already have a compatible controller, and in a worst-case scenario, you can route an analog VGA signal group from your motherboard to the controller internally. The only real difference would be some signal loss and noise because of the analog line, depending on shielding.

If you want an all-digital, bare LCD, you could try your hands at this bare LCD, which presumably uses TTL signalling:

http://www.allelectronics.com/cgi-bin/category.cgi?category=365&item=LCD-104&type=store

 

[James.]

Thanks for the reply. The link you posted isn't quite what I'm looking for. Mainly because of the large amounts of extra material around the edges of the screens.

To reply to your question about the mobile video screens, they use standard RCA connections for the video in, and the controllers will not accept a digital signal. (At least all of the bare and mounted LCD's that I've been able to get literature on, thanks to friends in the local car audio shops.)

There is also a DVI output board available, and I might look into that alternative. As well, they have an RGB board that supports TTL monitors. The biggest reason that I went with LVDS is that many of the laptops that I've tinkered with (Albeit they are all older models) use a ribbon cable LVDS interface from the mainboard to the display. That is basically what I am looking for; a very compact solution for a very compact device.

The quickest and easiest way that I can see about this is to get the one that sparked the idea in the first place, the Xenarc 700Y, and tear it apart. But that of course is also expensive, especially if I have to try more than once.

Specs of the Xenarc 700Y from their website:

Model #: 700Y / 700YV
Screen Size: Diagonal 7" (16:9)
Physical Resolution: 800 (H) x 480 (V)
Supported Resolution: 640 x 480 ~ 1600 x 1200
Dot Resolution: 2400 x 480 = 1,152,000 (dots)
LCD Panel Brightness*: 400 cd/m²
Display Brightness: 350 cd/m²
Operating Voltage Range: DC 11V ~ 24V, 1A
Power Supply: DC 12V
Power Consumption: <8W
Operating Temperature: 23°F ~ 158°F
Dimension (in): 7.75W x 4.75H x 1.38D
Weight (lb): 1.28
FCC, CE, E13 Certification
18 Month Warranty
Available in Silver or Black
No dead Pixel Guarantee

Items in bold are the items that are important to me.

This is the output to the transmitter. The specs for the actual transmitter board are:

Transmitter: Chrontel 7019
Supports 18-Bit Panel
Supports Resolutions up to 1024 x 768

Oh, and the voltage is adjustable, 3.3 or 5v. Thanks for your comments again.

Finally, here's a link to the PDF manual for the LVDS connector.