Projector lamp types
The general principle between the lamps used for projectors is simple. Small electrical discharge is magnified to produce light of High Intensity. So the name High Intensity Discharge is synonymous to the output of these lamps from the electrical source. Electrical discharge is a natural phenomenon found in lightning which led to the creation of the first `Metal Halide Lamps` that are used up to date with some modifications. Mercury is the element used in most of these lamps for its discharge and the light propagation. With the growing trend, lamp technologies have been enhanced to suit the specific requirements of projection and at the same time augment the color rendering capability of the lamps.
UHP (Ultra High Performance)
The basic difference between a normal lamp used for illumination and UHP is that instead of the wire filament, the latter involves electrical discharge between two electrodes with high pressure mercury vapor as the medium. Mercury vapor under high pressure and discharge temperature allows high color rendering effect even when made in small compact sizes. The major disadvantage in UHP lamps is the deterioration of the electrode and the performance with time due to the high temperature; thereby the capability of the lamp to reproduce the color spectrum fails with time. With a life time of over 10,000 hrs, the lamps engage only Mercury vapor and not any other halide as the medium.
Xenon Arc Technology
Recent developments in the Xenon arc technology has increased its use in movie projectors and places where day light needs to be imitated. The principle of working is similar to the UHP; here high pressure Xenon gas is filled in the space between the electrodes (as high as 300 atmospheres). With a power rating from 2 KW to as high as 15KW, these Xenon projector lamps are used in the famous IMAX projection systems. The very high temperatures produced require water cooling systems to reduce the damage that can incur from the high temperature. High luminous intensity and spectral distribution are some advantages of this technology.
NSH Technology
Metal halide lamps also led to the creation of the Ultra Violet lamps which used the UV spectrum to its advantage. This technology enabled reliable brightness that spread uniformly in the area without any flicker or intermittence in the output beam. Used in home theatres, business markets and in data projectors, the lamp enabled compact designs of the projectors with a high luminosity. With an average life ranging from 2000-6000 hours, the lamp is available as a bare model and with housing.
P-VIP Technology
Expanded as the Premium Video Projector lamp, the P Vip lamps are a type of metal halide lamp that is used for video projectors, televisions etc. This lamp taps the non usable mercury spectrum aided by the mercury under very high pressure to produce a multi-line spectrum that can be used for enhanced projection purposes. Suited to all operating conditions, these lamps have very long lives and produce very high luminance and a lesser loss in the form of luminous flux. With all the enhanced features this technology is the most preferred one for the long lasting performance of projectors.
