Why does fluorescent lamp need to be rectified? What is the role of the rectifier and starter?

Ballast effects: First, the circuit when the current suddenly changes, resulting in a momentary counter electromotive force, use this feature to the breakdown of the gas lamp, the lamp Qiliang. The second is to limit the current to the lamp a suitable operating voltage and current to maintain lamp lights work;
The role of starter are: ballast with fluorescent light.
Fluorescent lamp working principle is: when the power supply voltage is applied to the fluorescent lamp starter immediately poles through the ballast and the lamp filament. 220 volts immediately inert gas ionization starter, the glow discharge. The process of heat bimetal starter of thermal expansion, the poles of the starter contacts. Current through the ballast, starter and poles at both ends of the filament constituting the path. Quickly heating the filament current, a large number of electrons are emitted. In this case, since the starter poles closed, between the poles of the voltage is zero, glow discharge disappears, the tube temperature decreases; bimetal automatic reset, disconnect the poles. In an instant the poles disconnected circuit current is suddenly cut off, ballast have a great self-induced emf acting on the tube ends after the power supply voltage is superimposed. Heat emitted from the filament when a large number of electrons at high voltage is applied across the lamp, with great speed from the low potential side to the high potential side movement. In the process of accelerated motion, the inner tube argon gas molecules collide, so that rapid ionization. Argon ionization heat, heat the mercury vapor to produce, along with the mercury vapor is also ionized and emit intense ultraviolet radiation. Under UV excitation lamp phosphor lining to emit visible light. Fluorescent normal light after. Due to the continuous generation of alternating current through the self-induced emf ballast coil, coil, coil self-induced emf hinder change in current, then the ballast down from limiting the role of the current stability in the lamp rated current range inside, the voltage across the lamp is stabilized within the rated voltage range. Since this voltage is lower than starter ionization voltage across the lamp so that the starter will not work anymore.