Err, I didn't explain myself very well.
What I meant was this:
When "closed" ie black, the LCD panel is not completely opaque, it still
lets a lot of light through. So if you made an LCD shutter camera, the
film would get fogged even when the shutter was closed. To solve the
lack of opacity a mechanical shutter is used to cap the LCD screen
before and after exposure.
This problem is is addition to any diffraction and image aberrations
caused by imperfect light transmission when the shutter is "open" and,
as somebody else mentioned, the fact that the LCD panel absorbs a lot of light.
Hey, I just had an idea why you cannot find the patents: look for LCD
projection devices like Datashows and other video projectors. They are
the reverse of what you are talking about here, but the principle is the
same where the LCD array modulates and controls light transmission.
Vaughan
--
> >Even when "off" LCD displays are not completely opaque. I seem to
> >remember some high speed camera that uses LCD shutter, but it needs a
> >normal shutter (set to like 1/500s) to stop the film from being
> >unacceptably fogged: the normal shutter opens, the LCD shutter changes
> >state (opens/closes) then the normal shutter closes.
> >
> >
> >Vaughan
> >
>
> I think you meant "transparent"?
>
> Well, I didn't mean it had to be LCD only, it was just an idea that
> popped into my head, so I did a search on it. Since I work at the
> Patent Office, I am precluded from obtianing any patents myself. I
> don't know if there are other electrically activated mediums like LCD
> that could preform the same function. But bascially, the idea is to
> have a lens element, which could be perfectly flat (ie, not a lens
> itself), with concentric rings of varying width which could be
> acitivated via some kind of electronic means to emulate a mechanical
> diaphram. I suppose if there was such a material, it would have been
> invented already, probably by Minolta or Canon.
>
> Be seeing you.
>
>
> Dirk Wright
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