dark corners

[Marc Sira]

> The only problem with the 280 screens is that they seem to be subject 
> to the mysterious "darkening corners" after a while.  Still dont know 
> why.

I have a theory about this. I think the LCD sandwich is more open to
contaminants from the atmosphere at the corners. Something from the air (or
offgassed from the other hardware in the screen assembly) could seep in
very slowly over time, starting at the point of each corner. This wouldn't
itself darken the screen, but it might act as a sort of doping to facilitate
ion transport while the screen is on (this is one of the normal mechanisms of
temporary image persistence on an LCD). This explains why the corners turn
darker when the screen is being used a lot, and eventually revert if the
screen is left off for a prolonged period (but more slowly than normal
image persistence over the more central parts of the screen, and with a 
constantly worsening predisposition to return the next time the screen is
used).

This explanation requires that the contaminant doping facilitates further
contamination - that is, as the sandwich is infiltrated it becomes more
amenable to future infiltration, which allows the patch to extend as well
as darken further. In this case all 250/270/280 screens would get worse with
time. Or that same feature might actually be a result of the charge imbued by
the ion transport, so the condition would only worsen when the corners are
actually darkened (ie. recently or currently in use), so the condition would
only worsen with use. Or, the LCD sandwich might simply be physically
separating starting from the corners. Whichever the case, it would be
difficult to do anything about it. You could try resealing the corners and
edges somehow, but you might easily just make it worse, and the change occurs
so slowly and gradually that it would be difficult to measure any improvement.

(Without this worsening condition, you'd see something more like a fractal
tree growing inward from each corner, since there'd remain only one entry
point - the original compromised corner).

My 280 screen actually has a small amount of dark creep at the top edge of
the screen, even in the middle. The corners are all affected to various
degrees, and all but one are spreading out along the sides as well (the
exception is spreading toward the centre as if from the corner point). The
differences might reflect the LCD sandwich coming unglued in differing ways.

Or it could just be grues. Tiny grues, turning out the lights.

-- 
Marc Sira		|	toh at victoria.tc.ca
If you can't play with words, what good are they?