halogen lamp
Halogen lamps are divided into incandescent halogen lamps and metal halide lamps. Halogen incandescent lamps are similar in construction to incandescent lamps, with the difference that the glass bulb is not empty of air, but is filled with a halogen-gas mixture. Metal halide lamps use the light emission of an arc.
Halogens are reactive chemical elements in the 7th main group of the periodic table and have many free valence electrons. Halogens include bromine, iodine, fuorine and chlorine. In halogen lamps, the halogens bromine and iodine are added. This gives the halogen lamp a higher filament temperature, resulting in a whiter light and higher luminous efficacy. Color temperatures range from 1,000 K to 3,500 K.
Halogen incandescent lamps have a longer life than normal incandescent lamps, better efficiency and their brightness can be controlled via a dimmer. The efficiency of halogen lamps is about 15% compared to 5% to 10% for incandescent lamps, and the luminous efficacy ranges from 15 lumens per watt( lm/W) to 25 lm/W. Metal halide lamps have a much higher luminous efficacy, ranging from 60 lm/W to 100 lm/W. They achieve luminous intensities of 20 mega- candela (Mcd) in relation to one square meter.
In terms of lamp base, halogen lamps usually have pin bases or the classic threaded base. They are available as low- voltage and high-voltage halogen lamps. Low-voltage halogen lamps operate at 6 V, 12 V and 24 V and are operated via a transformer or an electronic ballast ( EB). High-voltage halogen lamps are operated directly from the mains voltage or via an electronic ballast at 230 V. The lamps can be used for a wide range of applications. The service life of halogen lamps can be increased to up to 4,000 hours by adding iodine or bromine. Halogen lamps are used in the home and for lighting objects or exhibits.
As for the use of incandescent halogen lamps, they can be used without restrictions until 2016. Halogen lamps that do not meet energy efficiency class B will be excluded from sale thereafter. In contrast, metal halide lamps are used in headlights of motor vehicles.