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The Technology Involved In Projector Lamp Function

Projector lamps are high intensity discharge lamps

A projector lamp that is used inside an LCD or DLP beamer projector is actually more accurately known as a High Intensity Discharge projector lamp module. High Intensity Discharge projector lamps (also abbreviated to HID lamps) are electrical projector lamps and a type of arc lamp that produce light from a relatively small but high intensity discharge which causes an electrical arc between two electrodes inside the projector bulb that are made from tungsten. These two tungsten lamp electrodes are housed inside a projector lamp arc tube which is either translucent or completely transparent, and made from either fused quartz or fused alumina. Inside this fused lamp arc tube are metal salts and gas salts. The purpose of the gas salts is to make it easier for the electric arc to initially form between the two lamp electrodes. It is the metal salts which intensify the light from the projector lamp since these are evaporated to form a plasma once the arc is generated and starts to heat up the bulb. This plasma actually also functions to reduce the power consumption of the projector lamp. High Intensity Discharge lamps produce a very high output of light when compared to their small size which means that they are compact yet powerful and efficient light source, and therefore ideal for use in front projectors and rear projection televisions.

High Intensity Discharge Projector Lamp technology occurs in the natural world

The electric arc technology seen in High Intensity Discharge Projector Lamps is actually a fairly common type of technology that is seen in the natural world and not just limited to projector lamps! When you see lightning happen during an electrical thunder storm, this is actually a kind of high intensity discharge. Before and during a lightning storm, high voltages build up in the storm clouds and are then discharged to the ground through the air. As this high electrical current shoots towards the ground it excites the nitrogen atoms in the air, which causes the lightning that we see. This lightning is like a giant scale version of the discharge arc in a projector lamp, so the clouds and the ground almost act as the two projector lamp electrodes.

Metal gases to improve the colour spectrum and intensity of High Intensity Discharge projector lamps

The thinking behind why a projector lamp frequently contains a small amount of mercury halide gas is also based on fairly simple principles. Many people may remember in chemistry lessons at school that if table salt a burned in a naked candle flame it results in a bright orange flame. This happens because the high amount of heat from the flame excites the sodium atoms in the salt, which produces the characteristic orange coloured light. When this was first applied by scientists who were developing projector lamp technology, they started to test what effect visible light other metals might have when subjected to high temperatures. These projector lamp scientists found that mercury was a perfect fit for high intensity discharge lighting and projector lamp applications because of this metal's high vapor pressure and increased emission in the visible light spectrum.

The origin of the metal halide lamp

Replacement beamer projector lamps for DLP projectors and LCD projectors can be further classified into the group "Mercury Halide Lamps". These types of projector lamps were invented in the 1960s Dr. Gilbert H. Reiling. Metal halide projector lamps are called this because they contain a mixture of argon gas, mercury gas, and a variety of metal halide gases mixed together all at very high pressures. The exact mix of the metal halide gases will actually influence the nature of the light that is produced by the projector and will affect mainly colour temperature by making the light from the projector lamp redder or bluer depending on the halide gas mix. All metal halide lamps used for beamer projector lamp applications produce a very good distribution of the three primary colours. This means that metal halide high intensity projector lamps can give out white light that can be as good as natural daylight in terms of the rendering of colours.

Metal halide projector lamp operation

A metal halide projector lamp functions in just the same way as the function of a high intensity discharge projector lamp described above. During the operation of the projector lamp, light is generated from the lamp when an electrical arc passes between two electrodes and excites mercury atoms to turn them to a plasma. Metal halide gases are used in metal halide projector lamps, as opposed to simply metal gases, because metal gases on their own normally have a vapor pressure that is actually too low to be effective in the projector lamp discharge. However, metal halide gases are vaporized much more easily and are also much less reactive. This combination increases projector lamp efficiency and keeps corrosion to a minimum.

Why are replacement beamer lamps so costly?

When the time comes to replace the projector lamp in a beamer projector, often projector owners are not aware that the cost of the new projector lamp they will need to install is significant. Sometimes projector owners expect the price of the new lamp to be similar to the cost of a regular fluorescent bulb. Unfortunately this is not the case, since the technologies involved in the output of light in these two lamps is very different and is much more complex in a high intensity discharge metal halide projector lamp, as described above. The main reasons for the increased cost of a replacement projector lamp over other types of replacement lamp are that the lamps inside multimedia LCD and DLP projectors function at incredibly high temperatures and pressures, and so the arc tubes of the projector bulbs inside them must be made from very high quality fused quartz to avoid them breaking and to provide the high quality light output that is required for home theatre and business projection applications. Frequently these projector bulb arc tubes may be molded and blown by hand to ensure quality and precision. Furthermore, the various metal halide gases used inside a projector lamp bulb, such as mercury halide gas, are also costly.

Although replacing a projector lamp is indeed an expensive proposition, Projector Lamp Experts Europe offers its customers the lowest prices on projector lamps in the European Union to help minimize this cost. If you need to purchase a new lamp module for your LCD or DLP projector, just give Projector Lamp Experts Europe a call. Visit our contact us section.


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