Glossary A–ZLetter P
Projector
A projector casts an image with light onto a surface, such as a screen, a wall, a window or a floor.
Its light output is given in lumens. Unlike a display, it has no fixed picture size; this follows from the distance to the surface and the lens.
In screen networks, projectors are used where very large or unusually shaped surfaces are to be filled: projections on facades, floors in entrance areas, shop windows with rear-projection film, museums and events. Several projectors can be combined with overlapping edges into one large picture.
Operators should bear in mind that a projected image depends heavily on ambient light; in bright rooms it quickly looks pale, and black is never darker than the surface itself. People walking through the beam cast shadows. Light source, filters and fans need maintenance, and the space between device and surface must stay clear. For permanent displays in bright rooms, a display is usually the more reliable choice.