A video projector is an electronic device that takes input audio/visual signals and outputs video onto any flat surface, which is most often a white or silver colored projector screen. Video projectors make it possible to create large images without needing a similarly-sized electronic display. They are often used for larger audiences such as theaters, conferences and presentations.
A video projector uses a video source input played internally on a small screen. Light is shone through the screen, then captured and focused by a lens or multiple lenses to display on a surface at a given distance. Most projectors today are digital projectors. Technologies commonly used in video projectors include Digital Light Projection (DLP), Liquid Crystal Display (LCD) and liquid crystal on silicon (LCoS). Video projectors can use different light sources like high-pressure mercury lamps, light emitting diode (LED), laser diode and Hybrid LED/laser diode systems.
Consumers look for a range of features depending on how the video projector will be used. These include brightness, contrast, resolution, color quality and focal depth. If a room is small, a video projector with a short focal depth, also known as a short throw, may be required. If a projector is to be used in a brightly lit environment, then brightness and contrast values are vital. When image quality is important, such as for presentations or entertainment, high resolution and good color quality is a requirement. High resolution can also help prevent viewers from perceiving the space between pixels, also known as the screen door effect.
A less common use of video projectors is in augmented reality headsets and heads-up displays (HUD). In some HUD and augmented reality headsets like Google Glass or Microsoft Hololens, the image a person sees appears to have a greater distance from the eye due to the use of tiny video projectors and mirrors. Additionally, video projectors can be used to project 3D images, also known as stereo imaging.