Fluorescent lamps work on the principle of an electric current passing between cathodes in a tube, the familiar long white tube in ceiling lighting, that contains a small amount of mercury and a gas like argon. The electricity excites the mercury, which generates invisible ultraviolet light that is absorbed by the phosphorous coating, which then releases visible light. In order to jump-start this process, a starter provides a surge of energy.
The traditional inexpensive starter installed with fluorescent lamps, the glow tube or glow starter, provides the surge of energy needed but presents problems. Due to the design of this starter, it sometimes takes several attempts to start the lamp. Because every attempt results in a strain on the filament, the life of the lamp shortens for each start. A fluorescent lamp with a glow tube starter should not be started and restarted; rather it should be left on for long periods of time. In addition, that flickering when the lamp starts means a glow tube is at work. Another sign of a glow tube is the blackening of the tube due to deposits created while starting. Glow tubes shorten the life span of the lamp; the more the lamp is started, the sooner the lamp will cease working.
Avoiding the flicker effect requires warming up the tube prior to starting the lamp. To accomplish that, an electronic starter closes its contacts while a circuit enters the tube to release some electrons and generate heat. When the electrons have moved sufficiently, the electronic starter's contacts open and a pulse enters the tube for the purpose of igniting the mercury. The warm tube becomes easier to start, puts less strain on the filament and leads to a longer life for the tube and lamp.
Another type of electronic starter functions like the single pulse but differs in that it sends several pulses into the tube. The purpose of this starter is to produce a quicker start and extend the lifespan of the tube, with a side effect of not blackening the tube.
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