Fluorescent lamp power supply with low voltage lamp polarity reversal

• Main Author: WALLOT; GEORGE P
• Format: Patent
• Language: English
• Published: 27.04.1982
• Subjects: ELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ARTCOLLECTIONS [XRACs] AND DIGESTS

A solid-state ballast circuit for starting and regulating a gaseous discharge lamp which is operated on direct current is arranged so as to permit the use of low voltage switching relays to effect polarity reversal of the lamp under load. A high voltage pulse source is connected in series with the lamp and a low voltage switching relay is connected in a manner to effect polarity reversal of the DC voltage applied to the combination of the high voltage source and lamp. The voltage appearing across the high voltage source is prevented from reaching the switching relays by virtue of a bridge rectifier circuit connected such that the pulse source and lamp appear as a current source for the rectifiers. The output terminals of the bridge rectifier arrangement are connected between the output terminals of the low voltage DC source thus limiting the voltage applied to the switching relays to a value not exceeding that of the DC source. The circuit also includes apparatus for monitoring the levels of lamp current and for disabling the lamp circuit if the monitored current exceeds a predetermined magnitude.