Low pressure gas discharge for fluorescent and compact fluorescent lamps

Operation mode of a low-pressure discharge lamp
Principle of a metal halide lamp, in this case a double-ended lamp with a quartz burner

Fluorescent and compact fluorescent lamps work based on the low pressure gas discharge principle. The glass tube on low pressure gas discharge lamps is filled with a noble gas at low pressure and a small quantity of mercury. The glass wall is coated with a fluorescent. Inside the housing, an electrical field develops between two electrodes and gas discharge occurs. The discharge process causes the mercury vapor to emit UV rays. Visible light is emitted as soon as the UV radiation makes contact with the fluorescent. The light color generated can be varied using an appropriate fluorescent mixture. Thus it is possible to create fluorescent lamps for all kinds of applications.The operation principle of high-pressure discharge lamps differs considerably from that of standard incandescent lamps. Light is produced by gas discharge that occurs in an arc tube between two electrodes after ignition. Electrical conductivity is established by ionized filler components. The electrodes are fed into a completely sealed discharge vessel.

During gas discharge, the additives (metal halides) and the mercury are excited by the current flow and emit the excitation energy in the form of their characteristic radiation. The mixture of different radiation components produces the desired color temperature and color reproduction properties. The mercury is completely vaporized in the operating state.

Advantages of low pressure gas discharge

  • Flicker-free instant start in EB operation
  • High degree of efficiency and economy

Fluorescent lamps for every application

LEDVANCE has a wide portfolio of modern, high quality and reliable fluorescent and compact fluorescent lamps to suit all requirements and tastes. Whether for private use or the professional sector - OSRAM fluorescent lamps stand out through their long service life, high level of economy and various light colors.

Mercury content far below the limit

Compact fluorescent lamps operate according to the low pressure gas discharge principle and therefore contain small quantities of mercury which is used for energy-efficient light generation. EU Directives (RoHs) determine how much mercury energy saving lamps and fluorescent lamps are allowed to contain. LEDVANCE is working continuously to reduce the volume of mercury required for lamps to work. For example, in recent years, the mercury content of OSRAM DULUX energy saving lamps and fluorescent lamps has been reduced to a comparatively low amount! This is far lower than the limit values applicable in the EU.

Not all lamps contain the same quantity of mercury because different dosing methods are used depending on the type of lamp. Most OSRAM DULUX lamps contain a mercury, iron or mercury/zinc pill that provides metallic mercury for the discharge process. One impressive aspect of these lamps is the rapid start-up time. Compact fluorescent lamps in the shape of an incandescent lamp, on the other hand, favor the use of mercury alloys (amalgams).


LEDVANCE manufactures its lamps according to the strictest protection regulations to ensure that the mercury is hermetically sealed within the lamp. It can only escape if the lamp is broken.