Osram Sylvania Inc.

Joseph Parisella

Qinghong Yu

Grigoriy A Trestman

John G Konopka

Richard H Koeppl

John H Selverian

Felix I Alexandrov

William D Koenigsberg

Thomas Schalton

Ayan Choudhury

Driss Baba

A ballast comprises an inverter having a transformer comprising a core, a primary winding, and a secondary winding for connecting to a lamp and providing voltage thereto. The ballast includes a fault condition detection circuit connected to the inverter for disabling the inverter to discontinue energization of the lamp when a fault condition occurs. The fault condition detection circuit comprises an other primary winding wound on the core of the transformer for receiving a voltage signal proportional to a voltage across the secondary winding, a voltage blocking circuit connected to the other primary winding for receiving the voltage signal from the other primary winding, and a capacitor connected between the voltage blocking circuit and ground potential. The voltage blocking circuit is configured to selectively conduct and block the received voltage signal as a function of the frequency of the received voltage signal.

Fault condition of detection circuit

A circuit () for powering a halogen lamp () comprises an inverter () and an output circuit (). During operation, the inverter () and output circuit () provide a magnitude-limited current to the halogen lamp such that the lamp power during an initial period is substantially less than the lamp power during a steady-state operating period. Preferably, output circuit () is a non-isolated circuit that includes a current-limiting inductance, and inverter () includes a frequency control circuit (R,C,C,Q,R,R,C) for operating the inverter at a higher frequency during the initial period so as to reduce stress upon the lamp filament and preserve the operating life of the lamp. The circuit () is especially suitable for powering low voltage halogen lamps.

Power supply for halogen lamp having an inverter and output circuit

A ballast () for powering at least one gas discharge lamp () having heatable filaments () includes an inverter (), a resonant output circuit () coupled between inverter () and lamp (), and a filament heating and ignition control circuit () coupled to inverter () and resonant output circuit () having a first resonant frequency and a second resonant frequency, wherein the first resonant frequency is substantially greater than the second resonant frequency. Filament heating and ignition control circuit () controls inverter () and resonant output circuit () during a preheat phase and during a normal operating phase. During the preheat phase, resonant output circuit () has an effective resonant capacitance corresponding to the first resonant frequency, and provides a first level of heating to the lamp filaments (). During the normal operating phase, resonant output circuit () has an effective resonant capacitance corresponding to the second resonant frequency, and provides a second level of heating to the lamp filaments () that is negligible in comparison with the first level of heating. Control circuit () monitors a voltage within resonant output circuit () in order to compensate for any variation in the parameters of resonant output circuit () and to ensure that an appropriate level of preheating is provided to lamp filaments ().

Ballast with filament heating and ignition control

A ballast (') for powering at least one gas discharge lamp () comprises an inverter () and an output circuit (&#x2032;). Output circuit (&#x2032;) includes an output transformer () and output connections () for connection to one or more lamps (). A secondary winding () of output transformer () includes a tap connection (). A voltage-limiting impedance () is coupled between the tap connection () and earth ground (). Tap connection () is positioned, and voltage-limiting impedance () is sized, so that the voltage between earth ground () and any of the output connections () remains below applicable limits as dictated by regulatory and/or safety requirements.

Ballast with socket-to-fixture voltage limiting

A ballast () for powering a lamp load () comprising one or more gas discharge lamps () includes an inverter (), a resonant output circuit (), and a control circuit (). During operation of ballast (), control circuit () monitors at least one voltage within one or more series resonant circuits of output circuit (). When the monitored voltage reaches a specified level, control circuit () directs inverter () to maintain its operating frequency at a present value for a predetermined period of time, so as to allow output circuit () to provide a suitably high voltage for igniting the lamp(s). If the lamp(s) ignite within the predetermined period of time, control circuit () ceases controlling inverter () to maintain its operating frequency at the present value, so as to allow for normal operation of the lamp(s). Control circuit () also provides a lamp stabilization function, in which the inverter operating frequency is prevented from falling below a specified minimum value, and a protective function, in which inverter () is deactivated in response to failure of the lamp(s) to ignite within the predetermined period of time.

Ballast with ignition voltage control

A ballast () for powering one or more gas discharge lamps () comprises an inverter (), an output circuit (), and an arc protection circuit (). Arc protection circuit () monitors an electrical signal within the output circuit (). When an arcing condition occurs at the ballast output connections (), the electrical signal includes a high frequency component having a fundamental frequency that is much greater than the normal operating frequency of the inverter (). In response to the high frequency component exceeding a predetermined threshold, arc protection circuit () disables the inverter () for a predetermined shutdown period. Arc protection circuit () also provides a restart function for periodically attempting to ignite and operate the lamps. Arc protection circuit () is preferably realized using a microcontroller integrated circuit () with associated discrete circuitry, and is especially well-suited for use in ballasts for powering multiple lamps via a current-fed self-oscillating inverter and an isolated parallel resonant output circuit.

Ballast with arc protection circuit

A ballast () for powering one or more gas discharge lamps () comprises an inverter () and a lamp fault protection circuit (). Inverter () has an operating frequency that is load-dependent. Lamp fault protection circuit () monitors an electrical signal within inverter (). In response to a change in the fundamental frequency of the electrical signal, such as what occurs when a lamp is removed, when a lamp approaches the end of its operating life, or when an arcing condition occurs at one or more of the ballast output connections (), lamp fault protection circuit () disables the inverter () for a predetermined shutdown period. Lamp fault protection circuit () also provides a restart function for periodically attempting to ignite and operate the lamps. Additionally, in response to a sustained fault condition, lamp fault protection circuit () increases the predetermined shutdown period so as to minimize any undesirable effects due to the restart function. Lamp fault protection circuit () is preferably realized using a suitable microcontroller integrated circuit () with associated discrete circuitry, and is especially well-suited for use in ballasts for powering multiple lamps via a current-fed self-oscillating inverter and an isolated parallel resonant output circuit.

Ballast with frequency-diagnostic lamp fault protection circuit

An electronic ballast () for powering at least one gas discharge lamp () includes a current-fed resonant inverter () and a load shed circuit (). Inverter () ordinarily powers the lamp at a first level. When a load shed command is sent by the electric utility and received by an associated load shed receiver within the ballast (), load shed circuit () causes the inverter to reduce the lamp power from the first level to a second level. Preferably, load shed circuit () includes an isolation circuit () and a bidirectional switch () that is coupled in parallel with a return ballasting capacitor () within inverter (). In the absence of a load shed command, bidirectional switch () effectively shunts return ballasting capacitor (), which causes the lamp to be powered at the first level. In response to a load shed command, bidirectional switch () ceases to shunt return ballasting capacitor (), thereby causing the lamp power to be reduced to the second level.

Electronic ballast with load shed circuit

An electronic ballast () for powering a lamp load comprising an even number of gas discharge lamps () includes an inverter (), an output circuit (), and a protection circuit (). During operation, protection circuit () disables the inverter () in response to an end-of-lamp-life condition that is characterized by a predetermined imbalance in the operating current provided to each of the even number of lamps. Preferably, the output circuit () includes a current-sensing transformer () for detecting the predetermined imbalance, and the protection circuit () includes a silicon-controlled rectifier () for disabling the inverter ().

Ballast with end-of-lamp-life protection circuit

A coil bobbin () has a housing () having a floor () with at least one electrical lead-in () projecting therethrough for attachment to a printed circuit board (). The at least one electrical lead-in () is provided with thermal-strain relief () between said floor () and the printed circuit board (). In a preferred embodiment of the invention the strain relief takes the form of a loop formed in the lead-in.

Lead-in for electronic bobbins

A ballast () for powering at least one gas discharge lamp () from a three-phase AC voltage source () comprises a three-phase rectifier circuit (), a high frequency filter capacitor (), and a high frequency inverter (). Preferably, three-phase rectifier circuit () is implemented by a six-diode bridge, and high frequency filter capacitor () can be realized by a film capacitor or a ceramic capacitor. Ballast () provides a high power factor and low total harmonic distortion without requiring a dedicated power factor correction circuit. Other benefits of ballast () include enhanced efficiency, longer life, and lower inrush current.

Three-phase electronic ballast

A ballast ( &prime;) for powering a plurality of gas discharge lamps ( ) includes a load-adaptable charge pump power factor correction arrangement ( ) for feeding back a high frequency current having a magnitude that is dependent on the number of operating lamps.

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Beverly, MA, United States of America

Joseph Parisella