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Lighting Systems, Inc.

William B Zelina

Francis John Zelina

Francis J Zelina, Jr

James E Hetherington

Applicant has provided a ballast circuit for fluorescent lights made up of the combination of (1) a source of electrical energy, (2) a resonant circuit, (3) a switch means for connecting the source of electricity to the resonant circuit, (4) means to connect the resonant circuit to a load, (5) a resonant current monitor controlling the switch means in synchronism with the resonant current so that the switch means switches the resonant current when the resonant current passes through zero. The resonant current monitor is a current transformer having a primary winding connected in series with the resonant circuit and two secondary windings connected to the bases of the two switching transistors in a two transistor inverter circuit at a polarity that will switch one of the transistors on and the other off at the time current passes through zero. This is the optimum time to switch the transistors since the current flowing through the transistors is passing through zero at that time and therefore the transistors operate at maximum efficiency and there are minimum switching losses and improves the efficiency of the circuit. The circuit will automatically adjust the switching frequency to the changed resonant frequency should the value of the inductor or the capacitor degrade and therefore change, and the switching losses will therefore be maintained at minimum.

Line operated fluorescent lamp inverter ballast

An inverter ballast for fluorescent lamps utilizing a resonant circuit coupled to the lamp and operated from a source of DC power through transistors. The transistors are controlled by a sensing means in the resonant loop which insures that the transistor switch at zero current. Furthermore, the coupling means for the load controls a source of heater voltage to the anodes of the fluorescent light which operate at very low current, an antisaturation circuit made up of separate windings are on the current transformer and connected to the switching transistor bases and through diodes to the power supply to prevent 'shoot through' current in the transistors. An autotransformer is used as a high leakage reactance transformer; and a circuit is provided to prevent overload of the resonant circuit in case of lamp failure. Shoot through currents are prevented, and overload of the resonant circuit is prevented, and an autotransformer coupling of the resonant circuit to the load is used.

Inverter ballast circuit with shoot through prevention, auto transformer

An inverter circuit suitable for use as a fluorescent lamp inverter ballast is disclosed. The inverter has the capability of starting the fluorescent lamp through regenerative feed-back techniques made possible by the amplification characteristic of the inverter switching transistor. Good efficiency at high frequency is provided by minimizing the transistor switching losses through use of resonant storage techniques and an unique feed-back system. Further, the normal energy lost in the feed-back circuit is eliminated by combining the resonant load means and the feed-back means into a single structure.

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Erie, PA, United States of America

William B Zelina