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:
Feb. 27, 2001
Filed:
Apr. 22, 1998
Antonio Canova, Arezzo, IT;
MagneTek, S.P.A., , IT;
Abstract
A supply circuit used in electronic ballasts for discharge lamps having an inverter for generating a supply voltage at a specified switching frequency for a load circuit comprising at least one lamp and a resonant circuit in series with the electrodes of the lamp. The supply circuit also includes a control circuit connected to the load circuit and the inverter so as to reduce the supply voltage provided to the load circuit in case of defective operation of the lamp. The control circuit includes a band-pass filter centered on the switching frequency of the inverter, a level discriminator, and a logic circuit. The control circuit receives an input signal that is dependent on the voltage at a point of the load circuit, and it is filtered through a band-pass filter. The output signal from the band-pass filter is provided to the level discriminator, which determines whether the lamp being used is defective by the frequency of the voltage and provides a corresponding high or low signal to the logic circuit. The logic circuit then provides a signal to the inverter so as to turn off the supply to the load circuit in case of defective operation.