A projector lamp is used to transfer an image from a multimedia projector onto a larger screen. Earlier halogen bulbs were used for many years for projection purposes, but were discontinued as halogen produced a yellow tone on the images. A projector lamp relies on an intense light bulb, called a metal halide bulb, to produce a brilliant white light. The light bulb shines onto a number of small mirrors inside the machine and transfers the image through the air and onto the screen.
These machines can project slides, films, or images drawn on a transparent sheet of plastic. There are three main types of projector lamps: Overhead projectors, Slide projectors, and Multimedia projectors.
An overhead projector has a flat base located beneath an intense light bulb. The bulb of the projector lamp causes the image to be sent to a special type of mirror, which enlarges and projects the image to a blank screen. Most overheads use an extremely high-power halogen lamp that may consume up to 750 watts yet produces a fairly dim, yellowed image. A high-flow blower is required to keep the bulb from melting itself due to the heat output. Further, the intense heat usually causes the halogen lamp to fail quickly, often lasting less than 100 hours before failing. A modern LCD or DLP uses an arc lamp which has a higher luminous efficacy and lasts for thousands of hours. A negative to LCD/DLP technology is the warm up time required for arc lamps.
Examples include use by educators to demonstrate writing samples for an entire classroom; business professionals use them during business conferences and meetings. Graphs, sales charts, and similar documents can all be shared at once rather than making numerous copies. An overhead projector lamp is generally the most affordable model, costing between 120 and 200 US dollars (USD).
Slide projector lamps contain a special slot for 35 millimeter slides. The image from each slide is enlarged and projected onto a big screen. The rest of the mechanism is similar to overhead projector lamps. Slide shows are great tools for business professionals and teachers who rely on physical camera images to teach or demonstrate the material at hand. Many photographers use 35-millimeter slides for special photography projects. Slides are easy to store and have a long life. A slide projector lamp typically costs between 190 and 300 USD.
Multimedia projectors are the most expensive of the three types of projector lamps. The machine transfers images from a videotape, film reel, or DVD and enlarges the image to a movie screen or blank wall. Multimedia projectors cost well over 500 USD, with a good quality multimedia projector costing between 800 and 1300 USD. Multimedia projectors are commonly used at movie theaters and in expensive home movie systems.
Projector lamps have been used in businesses and educational organizations for many years in order to help convey information to an audience. They are also used for movie or home theaters, where it sends DVD or film images to a large screen for all to see.