{{Short description, Electrical inverter A CCFL inverter is an

electrical inverter A power inverter, inverter or invertor is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). The resulting AC frequency obtained depends on the particular device employed. Inverters do the opp ...

that supplies

alternating current Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in whic ...

power to a

cold cathode fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet, ul ...

(CCFL). CCFLs are often used as inexpensive light units in electrical devices that are powered by

direct current Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or eve ...

sources such as batteries. CCFL inverters are small, have switchover efficiency over 80%, and offer adjustable output of light. They are widely used for backlights for LCDs, or for rear lighting in advertising signs.

History

As for the inverter circuit of a cold cathode fluorescent lamp, a resonance type circuit has been widely used. This is sometimes referred to as the " Royer circuit". However the proper definition of the Royer circuit requires that the inversion of a switching operation be performed in a state in which the transformer is saturated. An inverter circuit which performs the inversion operation by utilizing resonance in the collector circuit of a transistor is preferably referred to as the " Baxandall converter" in distinction from a true Royer circuit.P.J. Baxandall,
Transistor Sine-Wave LC Oscillators
, ''International Convention on Transistors and Associated Semiconductor Devices'', 25 May 1959, fig 5, p. 751 The multilevel inverters are basically classified into three topologies namely, the flying capacitor inverter, the diode clamped inverter and the cascaded H-bridge inverter. All the topologies have same property of reducing the harmonics. The cascaded has the disadvantage to need separate DC sources but circuit layout is compact and voltage sharing problem is absent. The early designs of an inverter circuit for a cold cathode fluorescent lamp did not utilize the resonance method of a secondary circuit at all. Instead the so-called closed magnetic circuit type transformer having a small leakage inductance was used as a step-up transformer. The leakage inductance was such that it reduced the output voltage on the secondary side of the transformer. Since this was not desirable, it had to be made as small as possible.

External links

# Jim Williams
"A fourth generation of LCD backlight technology: Component and measurement improvements refine performance"
Linear Technology Application Note 65, November 1995.

References

Inverters

History

See also

External links

References