Abstract: A fluorescent lamp electronic ballast includes a power factor correction flyback circuit and an inverter ballast circuit. The power factor correction flyback circuit is composed of a rectifier connected to a DC to DC flyback converter. The flyback converter includes a flyback transformer connected to a diode/capacitor combination. The flyback transformer is switched during operation to produce a flyback waveform that is rectified by the diode and results in a DC output at the capacitor. The inverter ballast circuit receives the DC output and converts the DC output to an AC signal for operating the flourescent lamp.

Abstract: A ballast for an arc discharge lamp load switches high voltage DC at a high frequency based on a low frequency control signal. The switched high voltage is then filtered to remove effects of the high frequency switching. Switching may be accomplished with a high voltage, AC voltage controlled current source generating a high frequency, high voltage substantially rectangular signal at a source output by switching the high voltage DC signal with the low frequency time varying reference signal.

Abstract: A fluorescent lamp electronic ballast includes a DC to DC flyback converter, a commutator circuit, and a current sensor. The flyback converter includes a flyback transformer connected to a diode/capacitor combination, and includes a switch used to produce a flyback waveform that is rectified by the diode and results in a high voltage DC output at the capacitor. The commutator circuit receives the high voltage DC output and converts the high voltage DC output to an AC signal for operating the fluorescent lamp. The current sensor senses a DC lamp current from the output of the flyback converter and provides a current sense signal to the flyback converter. The flyback converter switch is controlled based on the current sense signal. Preferred ballasts advantageously provide a continuously dimmable lamp load, a universal type ballast for a wide range of lamp loads and combinations, and programmed start.

Abstract: Problems in fluorescent lamp operation are determined by detecting an increase in voltage on a flyback transformer secondary due to the open circuit flyback effect. A ballast implementing the present invention supplies alternating power to ignite and maintain each lamp. DC power is provided to each filament from a multiple output flyback converter. A voltage level is sensed across at least one filament of each lamp. A determination is made that at least one sensed voltage level exceeds a threshold based on the flyback open circuit voltage.

Abstract: A variable color filter for fluorescent lamps has a color tube supporting colored filter strips disposed longitudinally along the color tube so that the strips are circumferentially adjacent to each other. A motor rotates the color tube inside a mask so that an aperture in the mask limits emission to light filtered by only a circumferential portion of the color tube. A controller positions the color tube in relation to the aperture to achieve a desired coloring of light emitted by the lamp tube.

Abstract: A ballast for an arc discharge lamp load switches high voltage DC at a high frequency based on a low frequency control signal. The switched high voltage is then filtered to remove effects of the high frequency switching.

Abstract: Problems in fluorescent lamp operation are determined by detecting an increase in voltage on a flyback transformer secondary due to the open circuit flyback effect. A ballast implementing the present invention supplies alternating power to ignite and maintain each lamp. DC power is provided to each filament from a multiple output flyback converter. A voltage level is sensed across at least one filament of each lamp. A determination is made that at least one sensed voltage level exceeds a threshold based on the flyback open circuit voltage.

Abstract: A fluorescent lamp electronic ballast for use with fluorescent lamps of the preheat or heated filament type is provided. The electronic ballast includes a multiple output DC to DC converter with a primary winding and a plurality of secondary windings for connecting to a plurality of lamp filaments. Each secondary winding is connected to a lamp filament through a diode/capacitor combination with a current transformer primary located in a high frequency loop. A sensing circuit is connected to a current transformer secondary. A controller is connected to the sensing circuit and controls the filament power supply. Advantages include the ability to predict lamp end of life, detect disconnected filaments and other problems that appear as an open circuit such as loose or misinstalled lamps and prevent arcing, detect smoldering of a heavily carbonized lamp holder, or detect short circuits.

Abstract: A fluorescent lamp electronic ballast includes a DC to DC flyback converter, a commutator circuit, and a current sensor. The flyback converter includes a flyback transformer connected to a diode/capacitor combination, and includes a switch used to produce a flyback waveform that is rectified by the diode and results in a high voltage DC output at the capacitor. The commutator circuit receives the high voltage DC output and converts the high voltage DC output to an AC signal for operating the fluorescent lamp. The current sensor senses a DC lamp current from the output of the flyback converter and provides a current sense signal to the flyback converter. The flyback converter switch is controlled based on the current sense signal. Preferred ballasts advantageously provide a continuously dimmable lamp load, a universal type ballast for a wide range of lamp loads and combinations, and programmed start.

Abstract: A fluorescent lamp electronic ballast for use with fluorescent lamps of the preheat or heated filament type is provided. The electronic ballast includes a multiple output DC to DC converter with a primary winding and a plurality of secondary windings for connecting to a plurality of lamp filaments. Each secondary winding is connected to a lamp filament through a diode/capacitor combination with a current transformer primary located in a high frequency loop. A sensing circuit is connected to a current transformer secondary. A controller is connected to the sensing circuit and controls the filament power supply. Advantages include the ability to predict lamp end of life, detect disconnected filaments and other problems that appear as an open circuit such as loose or misinstalled lamps and prevent arcing, detect smoldering of a heavily carbonized lamp holder, or detect short circuits.

Abstract: A power supply includes a control circuit that inhibits excessive input current draw during a low-line condition by decreasing a power supply output voltage in response to a measured change in either power supply input voltage or power supply input current. The power supply may be, for example, a cable television distribution network power supply that receives power from the coaxial cable that carries the television or other media signals or, in the case an optical fiber network, an auxiliary power cable associated with the fiber cable that carries the media signals.

Abstract: A ballast circuit for driving fluorescent lamps characterized by a minimum of components has a power transformer constructed to present a source impedance integrated with the transformer and in series with the lamp load sufficient to regulate the load current to within 10% for a selected maximum wattage fluorescent lamp load, such as 18 or 36 watt, and any lesser fluorescent lamp loads. The transformer has a high voltage secondary winding with a reflected impedance at least 6.0 times greater than the reflected impedance of the selected worst case fluorescent lamp wattage load. The integrated magnetics design of this ballast also provides passive short circuit protection, filament current reduction after lamp strike, and cold temperature start-up with a minimum of circuit components.