DLP and LCD TVs

How DLP TVs Work
DLP, which stands for Digital Light Processing, is made possible by a chip covered with thousands of tiny micro mirrors. How tiny are these mirrors? A hair on your head is about 100 microns in diameter (about a tenth of a millimeter). A micro mirror is about 16 microns by 16 microns. You could fit 25 of these mirrors onto the end of a piece of hair. A bright light shines onto the micro mirror chip. A computer can move the micro mirrors, each one individually. Engineers position the chip so that, if a micro mirror faces one way, the light reflecting off of it hits the screen. If it faces another way, the light reflecting off it is absorbed by a black light trap. By wiggling the mirrors on the chip back and forth very quickly, moving images are created on the screen.

These mirrors can flip back and forth incredibly fast. They put a wheel in front of the bright light with red, green and blue color filters on it, and spin the wheel. The mirrors shoot red light onto the screen, then rearrange and shoot green light, then rearrange and shoot blue light. The cycle repeats each time the color wheel makes a rotation.

The DLP system makes it possible to create big screens at low cost. But the screen usually isn't quite as bright or crisp as some of the other technologies available today.

How LCD TVs Work
Imagine a piece of glass that can be clear, or it can be black. And you can electronically control whether it is clear or black. That is the basic idea behind an LCD screen. An LC is a liquid crystal. When you sandwich some liquid crystal material between two pieces of glass, along with some clear electrodes that can control the LC, you can control how much light passes through the glass.

To make an LCD screen, you put a color light filter over the glass. The filter contains tiny red, green and blue areas. Behind the filter, you put your piece of liquid crystal glass. In this glass, you have millions of tiny electrodes so you can control millions of tiny LC shutters. Behind the glass, you put a very bright light.

A computer can control each tiny area of the LC glass. In this way, it controls how much light flows through each pixel, and the color of each pixel. By flicking the millions of LC shutters on and off in the right pattern, the computer can make moving images.