Projectors
There are two types of digital projectors.
Micromirror- These projectors are similar to DLP televisions. They use microscopic mirrors to reflect light shone from a high-powered lamp through a prism. The prism splits the light into the three component colors of red, green, and blue. Each color is reflected off of different mirrors to create a projected picture.
In actuality, most of the individual mirrors are flipped from "on" (reflecting light) to "off" (not reflecting light) and back again thousands of times per second. A mirror that is flipped on a greater proportion of the time will reflect more light and so will form a brighter pixel than a mirror that is not flipped on for as long. This is how the DMD creates a gradation between light and dark. The mirrors that are flipping rapidly from on to off create varying shades of gray (or varying shades of red, green and blue, in this case).
LCD- These projectors are similar to LCD televisions. They reflect high intensity light off of a stationary mirror covered with a liquid crystal display. A digital signal is sent through the liquid crystals which directs some of the crystals to let light be reflected through them and others to block it, which can create an image. Unfortunately, just like LCD TV’s, LCD projectors are prone to having faulty pixels, due to bad transistors.