Simple projectors with LCD technology possess only one-colour display, which is transilluminated by the projection lamp. Because the display absorbs up to 80% of the irradiated light, the brightness of these projectors is rather poor, but they are quite cheap and are fairly light in weight. They are ideally suited for making presentations away from the office. However, if the projection takes place on a larger screen, the appropriate presentation area must be darkened.
The projection lamp is probably the most important component of the beamer. This provides the brightness, which is necessary in order to project the desired image onto the silver screen. Apart from the appropriate brightness, at the same time, the lamp must offer a pure chromatic spectrum so that the colours of the projection do not get falsified. This cannot be realised with a normal electric or halogen bulb. The lamp is a real high-tech product with the appropriate price. Most projectors contain high-pressure, gas-discharge lamps, which generate their light from a discharge arc. These are not directly attached to the current supply but get the energy from a high – frequency generator. These high-tech lights have only a very limited life span.
These projectors have applications in a number of business sectors, including entertainment, shopping malls, trade shows, and clubs. The technology has a number of disadvantages. These include: a short life span of the LCD panels, higher maintenance costs, readjustment is necessary (on a continuous basis), and the different modules lack a homogeneous image (thus giving a chessboard effect). There are also colour and brightness discrepancies within the single-projection modules. Finally, the technology gives bad colour rendering.