The main types of lamps

Incandescent lamps:

These lamps use a tungsten filament placed in an inert gas or in a vacuum inside a glass bulb. The inert gas eliminates the evaporation of the tungsten and reduces the blackening of the casing. There is a wide variety of lamp shapes whose appearance is primarily for decorative purposes.

Incandescent lamps are still widely used for domestic lighting because of their low cost and compactness. However, for commercial and industrial lighting, their low efficiency makes them expensive to use, which is why gas discharge lamps are the most common choice. Thus, a 100W lamp has a typical efficiency of 14 lumens/watt, while a 36W fluorescent lamp provides 96 lumens/watt.

Incandescent lamps whose flow can be easily varied by reducing the supply voltage are still used when the variation in light is an important feature of use.

Tungsten filament is a compact light source that is easy to focus with reflectors or lenses. Incandescent lamps are very useful for lighting showcases for which it is necessary to orient the light beam.

Halogen tungsten lamps:

Similar to incandescent lamps, these lamps produce light in the same way, from a tungsten filament. However, the bulb contains a halogen gas (bromine or iodine) that chemically limits the evaporation of tungsten

For the halogen cycle, it is essential that the bulb has a wall temperature of at least 250 ° C to maintain the tungsten halide in the gaseous state and, therefore, avoid condensation on the bulb. This temperature involves making quartz bulbs, not glass, which reduces their size.

Most halogen tungsten lamps offer longer life than equivalent incandescent lamps, and with filament temperatures higher, it generates more intense whiter color light.

Halogen tungsten lamps are now widely used in areas where small size and a high level of performance are essential needs, including the lighting of theatrical scenes and film and television sets where orientation and variation flow are common expectations.

Low voltage halogen tungsten lamps:

Originally, these lamps were designed for slide and cinema projectors. At 12 V for the same power, the filament becomes smaller and thicker than for 230 V, which allows a better focusing, as well as an increase in the luminous flux due to the greater mass of the filament which allows a temperature of higher functioning. The thick filament is more robust. These advantages have not escaped the sales lighting market and, although they require a voltage-reducing transformer, these lamps are now widely used for shop window Projection lighting.