Lightweight fluorescent lamp ballast

Claim 1

A lightweight starting and operating ballasting means for starting and operating a fluorescent lamp means from a household source of AC energy, said fluorescent lamp means comprising an elongated tubular light-transmitting envelope having electrodes positioned therein proximate each end thereof, said electrodes each comprising an elongated tungsten coil having a lead-in member affixed to each end of each said coils and sealed through the ends of said envelope, said envelope enclosing a discharge-sustaining filling comprising mercury and a low pressure of inert ionizable starting gas, and a phosphor material layer carried on the interior surface of said envelope, said fluorescent lamp means having a normal operating voltage drop thereacross not exceeding about 65 volts, and said ballasting means having elements which perform with said lamp means in a starting mode and an operating mode as follows: a. said ballasting means in said starting mode consisting of a closed electrically-conducting current-interrupting means connecting exteriorly of said lamp means to one of said lead-in members at each end of said lamp means to form with said electrode coils a series electrode-coil-preheat circuit, resistor means of predetermined value and capacitor means of predetermined value connecting in series circuit exteriorly of said lamp means with said series electrode-coil-preheat circuit to form a composite series circuit, and said composite series circuit adapted to be connected across the standard household source of AC energy intended for operating said lamp means; whereby on application of said household AC energy across said composite series circuit, said electrode coils are preheated and the atmosphere within said lamp means envelope is ionized; and b. said ballasting means thereafter shifting to said operating mode by said current-interrupting means opening to open said electrode-coil-preheat series circuit, with the household source of AC energy then applied across said preheated coils to initiate and maintain a low pressure mercury discharge between said lamp electrodes, with the operation of said lamp means thereafter normally continuing as ballasted solely by said series-connected resistor means and capacitor means.