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:
May. 24, 1994
Filed:
Jun. 10, 1992
Ronald A Lesea, Redwood City, CA (US);
Metcal, Inc., Menlo park, CA (US);
Abstract
An embodiment of the present invention is a dimmable, high power factor, high efficiency electronic ballast comprising, on a single integrated circuit chip, a shunt regulator, a voltage reference, a high-temperature shutdown, an undervoltage lockout, a timer for start-up and restarting, a variable oscillator, a mode control, an op-amp for receiving a signal proportional to lamp current and for controlling the variable oscillator or the duty-cycle of pulses output in a closed-loop servo, and active power factor correction including an analog multiplier for receiving an AC voltage and an AC current sample, and for multiplying these together to result in a comparison with a DC voltage. The comparison produces a control signal for a MOSFET switch on a boost converter transformer that actively corrects the power factor at a rate set by the oscillator.