The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 16, 1984
Filed:
Oct. 07, 1980
Calvin E Grubbs, Garland, TX (US);
Thomas Industries, Inc., Louisville, KY (US);
Abstract
A thyristor/capacitor inverter bridge energizes the lamp circuit with a high frequency oscillating voltage derived from full-wave rectified line voltage. Lamp current is regulated by a commutation circuit which is synchronized with zero crossings of the thyristor current. When power is first applied, an initialization circuit initiates a time delay to permit lamp warm up and then enables the high frequency inverter to begin energizing the lamp load. A re-strike circuit generates pulses coupled to the commutation circuit to re-start it when the rectified line voltage falls below that which is necessary to sustain oscillation of the inverter. Fault detection circuits are included for detecting faults such as loss of primary power, thyristor over-voltage, and thyristor over-current for taking corrective action, such as inhibiting the inverter and commencing a new initialization sequence. In addition, in the case of thyristor over-current, which may indicate that both power thyristors are conducting at the same time, the power thyristors are commutated. A fault count circuit determines whether a predetermined number of such faults occurs within a preset time, and if so, the system is shut down and manual reset may be required.