LCD projectors are systems that display or project information or video onto a surface. LCD stands for liquid crystal display, the technology used to project images. They are the technological descendants of overhead and slide projectors, older systems which serve the same purpose. They are most commonly used for displaying images in presentations or lectures, but are also used in home theaters.
Video signals are comprised of three colors: red, green, and blue. LCD projectors contain a separate glass panel for each. Each panel consists of two plates of glass with a layer of liquid crystal between them. When a charge is applied, the crystals open to allow light through or close to block it. This opening and closing of pixels is what forms the image.
These devices use dichroic mirrors to split the light from the input source into red, green, and blue components. Each then passes through the corresponding panel, where pixels form an image. The three colors are then recombined in a prism before being projected through a lens. LCD projectors use separate panels for each color because it results in better color saturation than using a single panel for all three.
While all LCD projectors perform the same fundamental task, there are many different models available, and consumers should know what their projector will be used for before selecting one. These devices are priced based on several factors, especially resolution. The highest resolution ones are only worth the money for those who need to project fine details as accurately as possible. The right amount of brightness, measured in lumens, depends on the lighting conditions the projector will be used under, as well as audience size. A darkened home theater requires less brightness than a fully lit conference room.
Other factors in considering LCD projectors are portability, computer connectivity, and input options. Those with higher resolution weigh more and are therefore less portable. Those using multiple computers to make presentations should consider a projector that is easily compatible with different systems. Projectors used to show movies in a home theater should have component video inputs for the best picture quality.
LCD projectors are frequently compared to digital light processing (DLP) projectors. These use circuit boards with thousands of tiny mirrors to project an image. Their chief advantages over LCD projectors include smaller size because they do not use multiple LCD panels, better color contrast, and no pixelation effect like that sometimes seen on LCD devices. However, LCD projectors are still known for having better color saturation. Generally, DLP is more popular for home theater use.
