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:
Jan. 30, 2001
Filed:
Feb. 22, 1995
Ole K. Nilssen, Barrington, IL (US);
Other;
Abstract
An inverter-type fluorescent lamp ballast is, via a light switch, powered from the power line by way of two power conductors and one control conductor. From the light switch, which contains a switch means as well as an adjustment means, the control conductor is provided with an adjustable-magnitude DC voltage; which DC voltage is referenced to one of the power conductors. At the ballast, the DC voltage is introduced into the ballast circuitry via a diode, thereby to establish within the ballast a control voltage of magnitude substantially equal to the DC voltage. This control voltage is used for controlling the magnitude of the ballast's 30 kHz output current, thereby providing for light output control. The ballast itself is a self-oscillating half-bridge inverter loaded via a series-tuned high-Q LC circuit connected across its output. A pair of fluorescent lamps is series-connected across the tank-capacitor of the LC circuit. The inverter has two bipolar transistors, each driven by an associated saturable current transformer that provides for a transistor ON-time dependent upon the magnitude of an associated bias voltage. One of the transistors has a control arrangement connected in circuit with its associated saturable transformer and is operative to control the magnitude of its associated bias voltage. As the magnitude of this bias voltage is controlled, the magnitude of the lamp current is correspondingly controlled. The magnitude of the bias voltage is controlled as a function of the magnitude of the DC voltage.