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Making LCD Displays Snappier
newSlashUser points out a very interesting article at ExtremeTech about a new means of more quickly
controlling LCD panel response, so the old complaint that LCD panels make poor displays for gaming and high-motion video may be whittled down a bit. As a bonus, the change is all in the controller, so it doesn't require any change in the way the panels are manufactured.
The number of areas where CRTs were superior to LCD displays continues to dwindle. It used to be they were only smaller/lighter. But in exchange for that, you paid 4x as much, and if you typed faster than 40wpm all you'd see is a grey smudge for 15 seconds (I remember the monochrome, passive matrix screen on my Powerbook 145b). Now the prices are becoming dollar-for-dollar competitive with CRTs, they are still smaller/lighter, and now they might actually be able to handle Quake 3 Arena and look as good as my 20" monitor (and yeah -- they are pretty close to that now, especially with a still image, but...). I think the days of the CRT really are numbered this time around.
If you can get your LCD controller to run at 60-80Hz, you should be able to implement this technique in software: compute change-corrected frames, where the ``feed-forward'' bits disappear faster than the human persistence rate. There's plenty of CPU for this, and the psychovisuals help: any reasonable transient errors in the LCD response are likely to be masked by the fact that the changing pixels are likely changing due to motion...
I had always just sort of assumed that controllers already did this, since it's so obvious. Even better would be to have the controller actually measure the pixel modulation (which it it should be able to do using the same mechanism it uses to change it) and use feedback, which would likely provide even faster response.
Sadly, at the end of the day, the 40Hz limit on skewing reasonably priced panels over the full range will continue to be a problem. With feedback and feedforward techniques, can one use higher pixel modulation voltages to improve this as well? I don't know, but I would guess one could...
Two polarizing filters encase the liquid crystals in the LCD. One filter is etched with horizontal lines; the other with vertical. Light enters the liquid-crystal compartment parallel to the first filter's lines and follows the path of the liquid crystals. If the liquid crystals become energized, the crystals and light rays do not twist to become parallel with the second filter. Light rays reach the second filter perpendicular to its lines and cannot pass through to the viewer's screen image. If the crystals are not energized, they twist themselves and the light rays to allow light to pass through and illuminate the LCD.
. as p?article=articles%2Farchive%2Fg0903%2F36g03%2F36g 03%2Easp
taken from
http://www.smartcomputing.com/editorial/article
--- Metamoderating abusive downgraders since my 300th post.
As others have pointed out, the LCD stops the transmission of light when voltage is applied, hence giving you black.
But one other nit-pick: "I don't understand why you need power to produce black" - No you don't need power. You need Voltage. The LCD cell acts like a capacitor and does not pass DC electricity though it. So no current, and hence no power used.
Leakage would probably be in the micro-amp range.
--jeff
ipv6 is my vpn
Apple's LCD displays are probably the best that exist, beating out SGI by a large margin. I've never had a moment's problem playing Quake or Unreal Tournament on my TiBook or G4, using either the Studio or Cinema display.
Perhaps the solution isn't more hacks, but better hardware. Sure, it comes at a price, but I'd rather drop an extra couple hundred for something that actually works.
Hippies smell.
My time spent with Philips Flat Displays in Philips Components allowed me time to see this and many other LCD-ish technologies. If you look here at the papers about Motion Compensation, that is the stuff I saw, and in fact, our group was working on the drive electronics to make it work. David Parker, one of the authors on a couple of those papers, is a very cool guy, as were all of the guys at PRL in Redhill, England.
Unfortunately, the LCD panel business slipped into commodity mode too quickly, where 15-inch panels and the displays containing them had to be super-cheap, and that was where Philips wanted to be, so we tabled the project. The simulations, though, showed a drastic difference is clarity and response time, resulting in sharp images suitable for television or video gaming.
As an aside, someone asked about applying voltage to get black. This works best with active matrix displays, while passives use the normally-black approach (apply voltage to get white). If you remember your old laptop displays from back then, dark vertical lines in dialog boxes and the like created vertical lines that ran the height of the screen thanks to voltage leaking to all of the dots in a column, which is not a big problem for actives.
There is a lot of cool stuff in the future of displays. LCD tech of today sorta sucks/ Look for some very cool stuff in multidomain displays and OLED/PolyLED displays.