Hi Bob,

At 02:49 PM 12/8/98 -0800, you wrote:
>Even with the polarizer rotated for best performance at the viewing angle
>I wanted it was still not as good as the intended angle.
>
>I decided to mess with the rear polarizer. I still could not get the
>result I wanted.
>
>My resulting conclusion is that it's impossible to change the intended
>viewing angle of an LCD display, unless you can rotate both polarizers by
>some angle that isn't 180 or 90.

And before, you also wrote:

>Rotating 90 degrees does exactly what I need. I suppose I could cut the
>polarizer into 10 little pieces and reassemble them to get this effect on
>the whole display.

The fact that flipping the front one over (sticky side out) has ANY affect,
seems to me to suggest that it is not a linear polarizer(these work the
same way in either direction).  The only setup that I have seen cause this
behavior was a laminate of a linear polarizer and a birefringent plate
(causes components of the E field of polarized light along one axis to be
phase shifted relative to the other axis).

I just did a search for how LCDs work and got,among others, the following URL:

http://www.angleview.com/lcdwork/index.htm

Looking at this page and several others, it seems that only linear
polarizers should be involved in your LCD, and why they should be working
differently in one direction than in the other, I can't understand. It
would also seem to me that rotating 135 deg should invert the display
(normally black instead of normally white), and that rotating 90 deg should
make the thing not work at all (always white,since this would allign the
front and back polarizers).

I don't really understand the reason why the lcd has a specific viewing
angle. The only thing I can think of would be that the ability of the LC's
to twist the polarization of the light going thru them is dependent upon
the angle at which the light is hitting them. If this were true, I don't
think you could do anything with the two polarizers to make it work at a
different angle because the light going through would be unaffected by the
state of the voltage across the LC electrodes.

Then again, the pages I looked at might only have info on one type of
display, and there may be others which work very differently.

Hope this rather lame attempt helps somewhat!

BTW, I would be interested in what you find out in the end.

Sean


+-------------------------------+
| Sean Breheny                  |
| Amateur Radio Callsign: KA3YXM|
| Electrical Engineering Student|
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