I noticed something interesting on my Palm IIIc organizer, with a color TFT screen. When viewed from the left side, say 45 degrees from normal, all dark colors appear completely black. Light colors don’t turn black but they do turn darker. On the other hand, looking at it from the right side, all colors are lighter than normal. Any theories on why this happens? I didn’t think there were any asymmetries in an LCD.
That happens because the glass screen is polarized. If you have a pair of polarized sunglasses you can test this. Holding your glasses in front of you look through them at the display. Now rotate your sunglasses. At some point the screen will appear to turn almost black.
Polarization cuts 50% of the light passing through. When you have two polarized glasses and rotate them you get to the point where each glass cuts 50% of the light leaving nothing getting to you.
The polarization on your display cuts the light shooting off at an angle but leaves the light heading straight out. When viewed from an angle you lose the light heading for you. You’ll see the same thing happen with almost ant flat panel display.
I understand how polarizers work, but why the differense between looking at the screen from the right side vs. left side? And why does it look like it is “losing color” - i.e. white remains white (sort of), blue and red become black?
I believe you should see the same effect from the right or left. Different colors go first because they are different wavelengths. They get caught at slightly different angles. White light goes last because it is ‘all’ wavelengths of visible light. Even though some wavelengths get caught before others some are still left and shining through the glass (hence the not quite as white as it once was color change you described).
Actually, Jeff, scr4 is right: it is antisymmatric. I’ve noticed this effect before, too, with various LCD’s, but it’s usually an up-down difference, not left-right. I’ve also noticed that on my electronic dictionary, the “contrast adjust” doesn’t actually change the maximum contrast, it changes the angle at which maximum contast occurs.
Having said all of that, I’ll leave it to some other physicist who knows more solid-state and optics than I to explain. 
Most liquid crystal displays (LCD’s) are of the twisted nematic variety. Letmetry to explain in breif:
A liquid crystal is part liquid and part crystal. The molecules flow like a liquid but maintain orientational and sometimes positional order. Imagine the flow of people in a shopping mall before christmas. The peopleare flowing freely but they are all standing up straight.
The molecules in a nematic liquid crystal are usually long rod like molecules. In the liquid crystaline phase, the molecules will all be aligned so that their long axis is facing the same direction.
Interestingly, if you use a molecule which is non-symmetrical (You see i will answer the question) the axis of the molecules will rotate in a helical formation.
This twist can also be introduced mechanically, which is usually how it is done in LCD's. You will notice that a helix can be either right or left oriented. The variation from right to left probably has to do with the way you are veiwing helical twist.
As for the difference between white and other colors, it isprobably simply that there is more light to block, since color is simply derived from blocking the already lit red blue and green lights. The same mechanism is used for each color.
I could go on and on, since it is my research area.You poor slob don’t listen to the others (polarized indeed!) it’s obviously broken. Email me and I’ll send you my address for you to send me your color unit (pack it up nice now) and I’ll loan you a monochrome unit while I see if anyone has some use for the parts from your IIIc. Might take awhile… say a year or three.
I know ,I know my consideration is overwhelming but the milk of human kindness gushes forth when I see something I need… err…ah someone in need.