Compact fluorescent lamp and ballast arrangement with inductor directly

Abstract

Disclosed is a fluorescent lamp and ballast arrangement of the type having a lamp base for connection to a fixture that also accommodates a lamp base of an incandescent lamp. A ballast circuit contains a first conversion circuit which converts a.c. voltage to d.c. voltage and which has an electrolytic capacitor for smoothing the d.c. voltage. The ballast circuit further includes a second conversion circuit which converts the d.c. voltage into a.c. current and which includes a resonant inductor and resonant capacitor. A ballast housing has first and second ends spaced along a longitudinal axis of the housing and encloses parts of the ballast circuit. Only two lamp tube portions of the lamp terminate in the first end of the ballast housing, with the resonant inductor being positioned between the two lamp tube portions. Preferably, a pair of printed-circuit boards are positioned within the ballast housing, between the electrolytic capacitor and the resonant inductor, and are dimensioned to convectively shield the capacitor from the inductor and the lamp tube portions. Substantially all ballast components in addition to the resonant inductor and the electrolytic capacitor are preferably sandwiched between the pair of printed-circuit boards. Additionally, the electrolytic capacitor is preferably positioned at least partially within the lamp base. Employing all the foregoing features together has resulted in ballast component temperatures that are equal to, or lower, than ballast component temperatures on comparable high wattage (i.e., greater than about 20 watts) but much larger ballasts that are integral (as here) to the lamp.