Huh? Do you really think there are 10M connections *to* the glass? There are, perhaps, on that order of connections _on_ the glass but that's an entirely different thing. The lines/rows are multiplexed. Yes, and modern panels have smarts on the glass.
Not fast enough, without some accelerator hardware.
s
not fast enough for DVI,
but if he only wants all white/black he doesn't need to drive pixels all he need is a clock ~25MHz, hsync/vsync and all the color bits tied high/low to get white/black
an AVR/PIC etc. could do that
-Lasse
How about examining an auto-dark welders helmet?
This seems similar to the Hughes (?) devices I used ~1980 (though they were DIP40). IIRC, the output was "multivalued" -- not just a simple (2 level) translator -- to ensure DC stayed off the glass.
Yes, similar to the Hughes interface -- though I was driving a much smaller display (7x95). OTOH, a fair bit of overhead for a machine with a 2MB/s bus!
But, how does this all relate to current technology? My understanding is that new panels are treated almost as a sort of write-only DRAM. The electrical interface serving to store a charge in each "accessed row's" column cell instead of just presenting an instantaneous voltage across each cell.
No. There would be about 3000 (electrical) connections to said "glass" (that the electronics would have to "twiddle"). The 2 million cels are "driven" by cleverly manipulating the timing of voltages impressed on those row and column drives.
In simple, non-multiplexed glass, you drive the "common" with a (relatively) fixed frequency square wave. Any segments that you want to "illuminate" (misnomer) are driven with a signal that is
180 degrees out of phase.Of sorts, this is an AC version of driving an LED (which expects to see a particular polarity of DC to illuminate the indicator).
On (old) multiplexed glass, the common signal is replaced by a "common per row" while the columns are driven in/out phase to cause their "illumination". (think of a single row as a "simple, non-multiplexed LC display)
Where this gets tricky is when you look at the field across some other cell (pel) that is NOT in the selected row! I.e., one of the "electrodes" at that cell is bouncing around with whatever column voltages want to be impressed FOR THE CELL IN THE CURRENTLY SELECTED ROW (which is NOT "this one"). The other electrode (row) is doing whatever it needs to do to keep this row from being "selected".
To ensure the (not selected) cell does not illuminate, you want to keep the field across it at "0" -- despite the fact that one electrode is dancing around willy-nilly as required for the other cells in that column.
*New* glass (active matrix) puts a Q at each cell *on* the glass. That transistor effectively *stores* the value ("amount of twist") for that particular cell. In a sense, you've created a DRAM and are now tasked with "refreshing" it before the charge leaks out of each of those Q's.
No, that requires some electronics along with the "glass".
I want to know what the *glass* sees!
Which glass? It probably depends on the manufacturer. As you and others p ointed out, there are many ways of driving LCD/LED screens. They have dedi cated controller for the specific panel technology and it is unlikely that you can use (or even get) the glass without their controller.
FORGET *GETTING* THE GLASS!
Does the (un)availability of the glass invalidate the question? I can't go to the corner store and buy "lightning" -- does that mean I can't inquire as to its properties?
Actually the output was 6 levels, to cater for the multiplexing and DC avoidance. See the KS0083 datasheet, it is still available in the Net.
-- -TV
You answered the question with a question - not a good way to get information.
I just love derogatory chatter :)
Jamie
If you consider factual statements to be derogatory... ;-)
I didn't say I *wanted* to operate it as a light gate. Rather, I offered an example of the sort of information I was seeking.
I have a novel approach to a client's problem and needed a better understanding of how *current* LCD technology works before proposing it as a solution. I don't want to suggest they have custom glass designed only to discover the concept won't work (there's a fair bit of development dollars at risk).
Likewise, want to be able to argue effectively with them and, ultimately, the glass vendor about the approach I want to take.
If the *concept* works, they will undoubtedly approach a volume manufacturer for the prototype -- probably with some guarantee of the manufacturing that will follow and conditions restricting the sale of any similar products to others (until patent clears) as that manufacturer will have the only experience in the "solution".
I've seen the same approach used in other situations where a particular technology doesn't "quite" exist -- yet. (and, when the "customer" didn't want to have to bankroll the development only to watch others compete with *them*!)
My memory suggested 4 -- I have an image of a "staircase" waveform in my mind -- but I wouldn't put any money on that! :>
I looked at it when you first mentioned it in the hope that it would have been the (Hughes?) chip that I used (it wasn't). And, I am too lazy to uncrate old project files just to locate the schematics for a 30+ year old design! :<
So, is the electrical interface compatible with (dumb) multiplexed glass *and* the active matrix technology more commonly used today (e.g., in TV's, LCD monitors, etc.)?
Something like the dimmable windows on Boeing 787 Dreamliner ?
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