Geeky tech question - refresh serial or parallel on LCD?

RatLabGuy

RatLabGuy

You look like a monkey and smell like one too
Joined
May 18, 2005
Location
Churchville, MD
Hoping somebody here will know this.
On an LCD screen/projector that can use a digital (DVI) input, when the screen is updating, do/can all of the pixels flip simultaineously, or does the signal move across the screen in a serial fashion (top to bottom) like an analog VGA signal does?

I have such a projector in the lab, and using sensors/oscillosopce have confirmed that at least, with a standard VGA signal going in it still indeed does it in a serial fashion even though it's an LCD. However I assume this is only b/c this is the format of the driving signal and it must sync to this.

If I just had a !@#$ 20 ft DVI cable I'd test it out imperically!
 
Pixels are wired in parallel clusters therefore refresh is a function of all impedance drains on video out simultaneously peaking off the buss. Keeps 1/t to a minimum thus producing a flicker free refresh. This assumes backlights are at their peak.

Hope that helps.

:beer:
 
Hm. Well, kinda.... flicker-free refresh isn't the issue for my app. I'm not worried about how long they take to get on/off, but (if you have a whole screen change black to white) rather the time between when the 1st one comes on, and the last one.
A CRT start in the upper right and moves left to draw a horizontal line, then drops down 1 line and does the next, and so on. R-L differences are nearly zill, but time from top of the screen to bottom @ 60Hz is 16.666 ms.
I have a condition where I need 2 things, top and bottom, to appear at *exactly* (within 1 ms or so) the same time.

The question is, does an LCD draw by the same pattern if controlled via digital interface (DVI), or does it flip them all at once.

In talking with one tech, he says yes, LCD "draws" it serially like CRT, but DLP is a totally different animal and will flip them all at once.
C'mon now, I know we have some guys here that sell these things?
 
Wow....

you are taxing the memory.
Been a few years since I schooled on that side of the biz...want to hook anything up and clarify picture I am your man, but tech side....

*IF* I remember correctly.
LCD serials identical to CRT BUT in "clusters"
DLP is refract of internal frag scope. So it *should* be nearly instant wash.

damn, if it wasnt so late Id be crawling in the attic to pull out some lit.
If you cant find out let me know, I have the defintie answer here in hard copy just have to fig it out and look it up...
 
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