Physics 2000 Einstein's Legacy Laptop Screens

Laptop Screens

You mentioned before that a color laptop screen is somewhat like a TV screen, in that each pixel is made up of three "cells," red, green, and blue.

That's right. Each "cell" is one of those devices we talked about: two polaroid filters with a twisted liquid crystal cell between them, an electric field that can be adjusted, and a red, blue or green filter. A whole pixel would look something like this:

Click on the white control boxes in the back to turn each "cell" on or off. The square at the right shows the result, mixing the colors you've turned on.

I see--if you light up the red and green cells and darken the blue one, you get a yellow pixel, and so forth. But there are only eight possible colors you can get. I would think you'd need more subtle color variations than this--the way we did for color TV.

Exactly. So when you send light through that second polarizer, you don't want it to be an all-or-nothing proposition; you want to be able to let through any fraction of the light you desire. That means you'd have to change the amount that the liquid crystal twists the light.

That's right. Do you have any suggestions as to how such a thing could be accomplished?

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