Lutron Electronics Company, Inc.

Brent M Gawrys

Mark Stephen Taipale

Dragan Veskovic

Venkatesh Chitta

Jecko Arakkal

Mark Charles Fischer

Robert Charles Newman

Thomas M Shearer

Jecko J Arakkal

An electronic dimming ballast that accommodates miswiring of fluorescent lamp filaments (e.g., miswiring the corresponding lamp sockets) is disclosed. The electronic dimming ballast may drive a plurality of gas discharge lamps. Each gas discharge lamp may have a respective filament. The electronic dimming ballast, via the filament miswire protection element, may establish the same voltage across a first of the filaments regardless of whether the filaments are wired in series or in parallel. The filament miswire protection element may have an impedance that is approximately equal to an impedance of at least one of the filaments. The filament miswire protection element may include one or more capacitors, inductors, and/or resistors. The filament miswire protection element may include only a capacitor.

Filament miswire protection in an electronic dimming ballast

An electronic dimming ballast comprises a filament turn-off circuit for controlling the magnitudes of filament voltages supplied to the filaments of a gas discharge lamp. Each of a plurality of filament windings is directly coupled to one of the filaments and is operable to supply a small AC filament voltage to the filaments. The plurality of filament windings and a control winding are loosely magnetically coupled to a resonant inductor of an output circuit of the ballast. A controllably conductive device is coupled across the control winding. When the controllably conductive device is conductive, the voltage across the control winding and the filament windings falls to zero volts. The controllably conductive device is driven with a pulse-width modulated (PWM) signal so as to control the magnitudes of the filament voltages. The filament voltages are provided to the filaments before striking the lamp, and when dimming the lamp near low end.

Apparatus and method for controlling the filament voltage in an electronic dimming ballast

A ballast for driving a gas discharge lamp comprising a rectifier stage having an alternating current (AC) input and providing a rectified output voltage, a boost converter stage receiving the rectified output voltage as an input and providing a boosted direct current (DC) output voltage across a DC bus, an inverter output stage for converting the DC bus voltage to a high-frequency AC output voltage to drive the lamp, further comprising a control stage receiving a desired light level signal controlling the desired light level of the lamp and providing an output control signal for turning the boost converter stage on or off in dependency on the desired light level signal. The ballast thereby has reduced power consumption at low light levels for greater energy efficiency.

Lighting ballast having boost converter with on/off control and method of ballast operation

An electronic ballast for a fluorescent lamp has a single-switch flyback inverter including a magnetizing inductance, a resonant circuit connected to the output of the inverter including a tank inductor, and a clamp circuit including a diode coupled to the primary winding of the flyback transformer for limiting the voltage across the magnetizing inductance when the switch is non-conductive. With the inverter switch conductive the resonant circuit has a first resonant frequency. With the inverter switch non-conductive, the resonant circuit, combined with the magnetizing inductance, has a second resonant frequency lower than the first. The magnetizing inductance is chosen such that the second resonant frequency is close to the first resonant frequency. The operating frequency of the inverter is controlled to be at or about the second resonant frequency, whereby zero current switching is achieved in the inverter switch.

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Allentown, PA, United States of America

Brent M Gawrys