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How does a video projector work? And the lamp?

Have you ever wondered how a projector lamp works? One of the key elements in the operation of these faithful companions in classrooms and corporate conference rooms. Projector lamps are very different from traditional lamps or lamps used in other projection applications, and here's why.

The projector lamp is a UHP (ultra high pressure) lamp. It is classified as a metal halide lamp. In short, the projector lamp works thanks to electrodes in mercury, which send an electric current to an LCD or DLP panel. It is this electric current that allows the emission of light.

Not all video projectors are based on the same technologies, each with its advantages and disadvantages. The main projectors use either LCD or DLP technology. The newcomers to the market now offer laser technology.

Generally, a projector lamp is supposed to last between 2000 and 6000 hours. However, there are hybrid lamps that can last up to 20,000 hours of use. These are laser and LED lamps, which ensure considerable energy savings.

DLP (Digital Light Processing)

Inside a DLP system is a micro-mirror array (DMD), with the image being reflected after being amplified by light from the lamp and a lens. A chromatic disc then filters the white light before it reaches the DLP chip, to finally project the image. DLP technology is also called DLP/DMD or DMD (Digital Micromirror Device). It was originally developed by Texas Instrument.

Among the many advantages of this technology: deep blacks, color intensity is well preserved, and it offers better response time. However, DLP lamps have a rather short lifespan.


A special lamp (metal halide lamp) emits light which reflects off three LCD panels corresponding to red, blue and green. The images are then reconstructed and finally projected.

Advantages and disadvantages: good image definition, increased brightness, more natural colors. A frequent drawback:the contrast is often lower on LCD projectors.

The laser

The operating principle is the same as for the DLP video projector, with the only difference of the lamp:it is replaced here by red LEDs and a blue laser (Blu-Ray).

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Advantages and disadvantages: the advantages of laser projectors are numerous, starting with the lifespan of the lamps... Indeed, the lamps of laser video projectors have a very long lifespan (up to 20,000 hours). This type of lamp also ensures more stable colorimetry as well as higher luminosity (up to 5000 lumens for certain models).

The disadvantages of the laser:a less good definition than the other types of lamps. On the other hand, according to experts in the field, over time this technology should also allow high definition, and some manufacturers are already beginning to market HD laser video projectors.