Digital projector
A digital projector is an electronic device which projects an optical display of digital video input. The device receives a video signal (usually analog can be accepted as well as digital) from a computer, media player, or other device which supplies a video feed.
Process
The most common kind of digital projector uses a Liquid Crystal Display to create a mirror image of the required output within the projector. A bright light (usually from a metal-halide lamp) is then shone through the display and out of the projector. The beam of light then shows the intended image when it refracts off a flat surface, to the viewer(s). Other methods using prisms and dichroic mirrors also exist, which each have their benefits and drawbacks.[1]
The lamp itself also can vary form one projector to another, but whatever is used must provide intense light. This means that the bulbs must be specially designed, making them expensive but also fragile. They also generally produce a great amount of heat (Light emitting diodes produce less, but still some) which can be harmful to them and their surroundings. Projector lamps must be slowly cooled after use, to prevent the bulb from being destroyed. For this reason, most devices include a cool-down cycle, which runs the onboard fan to cool the lamp at a controlled rate, and prevents it from being switched on again until the cycle has completed. Most projectors will also slowly ramp up power to the lamp, so that it can heat gradually. Those which do not use such protective features tend to require more frequent lamp replacement.
Uses
Digital projectors, although fairly expensive, have become quite popular for a number of purposes. In general, they can display video output to an audience for any number of purposes. They are frequently used by speakers and lecturers to display slideshow presentations while they speak. Teachers and professors in educational institutions also commonly use them this purpose.
For many years, movie theaters have been using projectors to show movies. This was true long before digital projectors, but these newer projectors have been adopted for the same purpose. They are much simpler to use, require far less space, and can be less expensive over-all. Theaters use these projectors to display on indoor and outdoor screens alike.
Some people also use digital projectors for private entertainment systems. For reasons such as display size and device size, some are willing to pay the extra expense of a digital projector for personal use. As the technology improves, so does the output resolution as well—many modern projectors offer at least an HD 1080p display.[2]
Many churches and chapels also use projectors. In some cases, they are used to display slideshows or other visual material while the pastor or minister is speaking. In other cases, they are used to show the lyrics to a song or hymn so that the congregation may sing along.