Laptop LCD's as Marquee?

[ojstimpy]

Has anyone ever attempted making a marquee with Laptop LCD's? I've been researching applying two LCDs together to make a marquee in my arcade machine. I've noticed that it may be quite expensive as a chip set (200$ up) would be required (power and controller) for each Laptop LCD to be used as a regular monitor. Then comes the fact that a front end would also need programming to display the game marquees on the LCDs. Just wondering if anyone has attempted this yet and if they can provide any additional info.

[BobA]

Laptop LCDs make it hard.   It has already been done with LCD TVs of sufficient size.  You just hide part of the TV or use it for other purposes.   Cannot remember the thread but it is here somewhere.

[Blanka]

The screens interface with DVI and the backlight inverter can be powered of the Notebook adapter, so electronically nothing to worry about. You just need to figure out the pin out details of the screen band cable. Try benheck.com, there's a lot of screen hacking on that site.

[sarge]

Just something else to consider but depending on your cabinet design laptop monitors usually have a terrible viewing angle when it comes to looking up at the monitor.  This may or may not affect you depending on your design but just something to keep in mind.

[BobA]

Finally got around to finding the original LCD Marquee thread.  Randy T made a great color LCD Marquee for his cab.

Original LCD Marquee Thread

[MonMotha]

I've NEVER seen a DVI laptop panel.  I don't doubt that they exist, but all of them I have seen have either been LVDS or (very recently) DisplayPort.

[Blanka]

LVDS

LVDS is analog. That would be stupid to use.

[MonMotha]

No, LVDS is digital.  LVDS is "Low-Voltage Differential Signalling".  LVDS for LCDs and DVI are electrically somewhat similar (they both use differential signalling at relatively low voltage), but the line coding is different.  LVDS is simple NRZ (maybe 8B/10B) while DVI uses TMDS.  The actual voltage and current specs also differ some.

LVDS is actually used for lots more than just LCD panels, but they are a common application.  They are in fact so common, that saying "LVDS interfaced LCD" colloquially specifies a specific de-facto standard.  The electrical side is somewhat specified by National Semiconductor as "FPDLink".  TI also makes parts under the name "FlatLink".  There's a JAE connector that lots of manufacturers seem to use (though there are unfortunately two different pinouts).  On this connnector is panel power, some control signals including DDC, an LVDS clock (1/7th the bit rate on the data lines) and then 3/4 or 6/8 data pairs.  The RGB data, DEN, and sync signals are placed into certain bit positions in the serialized data stream and sent to the panel which deserializes them back out into parallel digital RGB+sync supporting up to 18-bit color for 3 channels, 24-bit color for 4 channels, and then interleaved data on the 6/8 channel version to lower the clock rate as high resolution panels can have rather high data rates (it's 7x the pixel clock for 3/4 channels or 3.5x the pixel clock for 6/8 channels).  This is similar to how dual-link DVI works.

The 3/4 channel version seems to only have a single pinout on the standardish connector.  The 6/8 channel version has two.  One just haphazardly adds the additional channels in while the other attempts to provide some compatibility.  Of course, some laptops use a non-standard connector.  I'm not a fan of that JAE connector, so I can understand why.  The interface is usually still the same.  Both of my laptops claim to have an LVDS panel interface.

Other things that use LVDS (it's a standard unto itself, though there are lots of tweakables) are PCI Express, SATA, SCSI (parallel at low speeds, SAS at much higher speeds), and IEEE-1394 aka Firewire.  DisplayPort also uses a similar physical layer, though I've not confirmed if it is in fact LVDS compliant.  SATA also has additional "out of band signalling" that makes it not strictly LVDS.

http://en.wikipedia.org/wiki/Low-voltage_differential_signaling
http://en.wikipedia.org/wiki/FPD-Link