Wayne K Mans

US Patent:

50235184, Jun 11, 1991

Filed:

Dec 12, 1988

Appl. No.:

7/283255

Inventors:

Wayne K. Mans - Bridgewater NJ
Vincent J. Rizzo - Basking Ridge NJ

International Classification:

H05B 3702
H05B 4116
H05B 3904
G05F 100

US Classification:

315219

Abstract:

A ballast circuit for a gaseous discharge lamp, particularly a neon light, includes a diode bridge rectifier for producing a d-c voltage from an a-c input and a transformer with a secondary winding connected to the lamp and a primary winding connected to the rectifier. A switching circuit is connected to the transformer primary winding for controlling a flow of current therethrough from the rectifier. The switching circuit includes at least one MOSFET having a drain terminal connected to the transformer primary winding and a grounded source terminal. A control circuit is connected to a gate terminal of the MOSFET for controlling the on and off times thereof, the control circuit including a pulse generator for producing a train of pulse-width-modulated rectangular pulses of substantially a single frequency fed to the MOSFET's gate terminal. The pulse generator includes circuitry for changing the width of the rectangular pulses to enable a gradual energization of the gaseous discharge lamp from one end thereof towards an opposite end to create a writing effect of selectively different speeds in the gaseous discharge lamp. The circuitry in the pulse generator for changing the pulse width can be used to control the widths of the pulses so that the pulses are a train of square waves having a common duration equal to an interpulse period, whereby striations are generated in the gaseous discharge lamp.