A portable projector is a projector which has been designed to be moved around as needed, rather than installed in a fixed position. There are several different types of portable projectors, and these devices range considerably in cost, depending on the type and the age of the equipment. A portable projection system can be extremely useful for a school or office, allowing people to give presentations with the projector without needing to install a projector in every room.
One very crude form of portable projector is the overhead projector, a type of projection system which is often used in schools. Overhead projectors allow users to place a sheet of transparency paper with printed information onto an illuminated pane of glass, with the image being projected with a system of mirrors. These projectors are very useful for situations in which static information needs to be projected for everyone in a room to see.
It is also possible to find portable slide projectors, which work by allowing the user to click through a series of slides mounted in a tray. This type of projector is often used in art classes and history classes, to allow students to see examples of the topic under discussion. Other projectors hook up to a computer, allowing people to bring up documents, presentations prepared on the computer, and so forth. These projectors are often used in computer literacy classes to show students what they should be doing.
The fanciest portable projectors are projectors which are designed for showing films. They may work with film, discs, videocassettes, and hard drives, and they are often mounted on a projector cart which accommodates a sound system so that the projector can act as a self-contained unit. These projectors can become quite costly, because of the added technology needed for video and sound playback.
In order for a portable projector to be effective, it needs a surface to project against. A plain wall can do the trick in a pinch, but a projector screen is usually better. In establishments where portable projectors are used, pull down screens which roll up against the ceiling when not in use are popular. It is also possible to use portable screens mounted on tripods, as for example when people want to show films outdoors on a lawn with a portable projector and screen.
Sometimes, portable projectors are available for rental, which can be a useful option for people who need a projector for a very specific purpose, like a summer film festival. This option allows people to access high-quality projection equipment without needing to pay full cost.