What is the difference between lcd and led and plasma and crt and projector?

Answer 1

An LCD, or Liquid Crystal Display, is one that uses liquid crystals that allow certain wavelengths of light through, depending on how they are activated with an electric charge. Depending on how the crystal orients, they can let through no light, green, red or blue light, or white light. Most LCD's are lit from behind using a fluorescent bulb. An LED is an LCD that is lit from behind using an array of Light Emitting Diodes, which are much brighter, resulting in a display that is much crisper to the eye. Most projectors now are LCD projectors, that use dichroic mirrors to split white light into three specific colors. These three light beams are then combined in a dichroic prism to produce a full image that is transmitted through a projector lens. A plasma display uses gas plasma that reacts to an electric charge by emitting a specific color of light, much like a neon tube reacts to an electric charge. Each pixel of a plasma display has three separate cells, each containing a gas plasma that will emit either red, blue or green light when charged. Finally, a CRT, or Cathode Ray Tube display uses a charged cathode in a vacuum tube to create a stream of electrons that strike the screen. The screen is coated on the inside with phosphor, which glows when the electrons hit it. A special filter on the inside angles the electron stream so that it produces the correct colors on the screen.