Lighting A to Z

Fluorescent Lamp PartsBasePhosphor coatingElectrodeBulb wall Gas fill MercuryBulb wallA glass tube or bulb coated with phosphors.Gas fillUsually an electrically conductive mixture of neon and argon gasis used. Krypton is used in Econ-o-watt lamps.MercuryAll fluorescent lamps contain a small amount of liquid mercurywhich vaporizes during lamp operation. Philips ALTO ® lampscontain less mercury than standard lamps.BaseThe base is cemented to each end of the lamp to connect thebulb to the electrical circuit.ElectrodeThe electrodes are a coiled tungsten wire that conductselectricity to the gas fill. The electrodes are sputtered away asthe lamp starts and is vaporized as it operates. When theelectrodes are used up, the lamp can no longer start. Philipsbulbs contain an exclusive electrode guard that minimizes endblackening (shown on page 28).Phosphor CoatingPhosphor coating on the bulb wall converts ultraviolet energyto visible light in a process called fluorescence. Newer, moreexpensive phosphor coatings are used on bulbs with high colorrendering and higher light output.Lighting A–Z 19