Abstract: Disclosed is a high-power ballast inexpensively applicable to a fluorescent lamp of the 28-Watt class without any increase in the number of constituent elements used or any complexity in the manufacturing process. The high-power ballast includes a rectifier circuit for rectifying a low-frequency AC voltage to convert it into a direct current DC voltage, a power factor compensation circuit for compensating a power factor for the voltage outputted from the rectifier circuit, thereby boosting the level of the output voltage, the power factor compensation circuit including an active type power factor driver, and an inverter circuit for converting the DC voltage, outputted from the power factor compensation circuit, into a desired high-frequency AC voltage. The inverter circuit includes an inverter, a resonator circuit connected to the inverter, and a high-power piezoelectric transformer having an input terminal connected to the resonator circuit and an output terminal connected to the fluorescent lamp.

Abstract: A digitally controlled electronic ballast with a piezoelectric transformer automatically controls the brightness of a lamp in a digital frequency modulation manner. The ballast power a rectifier for rectifying an input low-frequency AC voltage to obtain a DC voltage, a power factor improving circuit for maintaining the level of the DC voltage output from the rectifier constant, an inverter for performing a switching operation, a resonance circuit for transferring a high-frequency AC voltage output from the inverter to the lamp. The resonance circuit includes a coil and a high-power piezoelectric transformer. A digital controller is provided for modulating a frequency controlling a switching period of the inverter when the lamp is turned off/off. The piezoelectric transformer is made of a composition expressed by Pb1-aSra[(Ni½W½)b(Mn⅓Nb⅔)c(Zr1-xTix)1-b-c]O3+kPbO.

Abstract: A digital controlled electronic ballast with a piezoelectric transformer which is capable of supplying high power of the 28-Watt class to the ballast, whereby the ballast automatically controls precisely the brightness of a lamp in a digital frequency modulation manner and applies stable voltage and current to the lamp.

Abstract: Disclosed is a high-power ballast inexpensively applicable to a fluorescent lamp of the 28-Watt class without any increase in the number of constituent elements used or any complexity in the manufacturing process. The high-power ballast includes a rectifier circuit for rectifying a low-frequency AC voltage to convert it into a direct current DC voltage, a power factor compensation circuit for compensating a power factor for the voltage outputted from the rectifier circuit, thereby boosting the level of the output voltage, the power factor compensation circuit including an active type power factor driver, and an inverter circuit for converting the DC voltage, outputted from the power factor compensation circuit, into a desired high-frequency AC voltage. The inverter circuit includes an inverter, a resonator circuit connected to the inverter, and a high-power piezoelectric transformer having an input terminal connected to the resonator circuit and an output terminal connected to the fluorescent lamp.