Motorola Corporation

Osram Sylvania Inc.

Zenith Electronics Corporation

Motorola Lighting, Inc.

A. W. Sperry Instruments, Inc.

Osrom Sylvania, Inc.

John G Konopka

Sameer Sodhi

Dennis L Stephens

Himamshu V Prasad

Peter W Shackle

Jeffrey D Merwin

Mihail S Moisin

Shashank Bakre

Qinghong Yu

Joseph Parisella

Anand K Upadhyay

Grigoriy A Trestman

Robert A Priegnitz

Naveen Yadlapalli

Kenneth D Labudda

Kent E Crouse

Guang Rong Liu

Sivakumar Thangavelu

Young G Kang

J Ray Wood

Bhadresh Mehta

Warren Moscowitz

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 at least one gas discharge lamp () at two selectable light levels includes a sensing transformer () and a detector circuit (). Detector circuit () provides an output voltage that is dependent on the states of two on-off switches (S,S) interposed between the ballast () and a conventional AC source (). The output voltage of the detector circuit () is used to control the illumination level of the lamp ().

Two light level ballast

The transmitter of the circuit breaker locator draws large amplitude, short duration, phase locked unipolar pulses of current from the power source at a frequency lower than that of the AC line frequency. The audible and visual indicators of the transmitter are triggered at the rate of the current pulses drawn from the AC line. The receiver of the circuit breaker locator has a pick-up coil that responds to magnetic field surrounding the circuit breaker, an amplifier for boosting the signal from the pick-up coil, and a single shot pulse stretcher triggered by the amplifier. The pulse stretcher drives both audible and visual signals, and at the same time charges a memory capacitor in a staircase generator fashion. The magnitude of the memory capacitor voltage in turn controls the gain of the amplifier. A switch controls the voltage applied to the amplifier, which increases by a predetermined amount when released.

Device for locating and identifying circuit breakers

An electronic ballast () for powering at least one gas discharge lamp () at two light levels includes a full-wave rectifier circuit () and a detector circuit (). Detector circuit () provides an output voltage that is dependent on the states of two on-off switches (S,S), but that is substantially unaffected by typical X capacitances that are present between the hot and neutral input connections of the ballast.

FA ballast () for powering a gas discharge lamp () comprises an inverter () and an arc protection circuit (). Arc protection circuit () monitors an electrical signal within the ballast. In response to occurrence of a disturbance in the signal, such as what occurs during output arcing, arc protection circuit () disables the inverter () for a timed shutdown period. Arc protection circuit () provides a timed starting period for igniting the lamp, during which time any disturbance in the electrical signal is essentially ignored and inverter () is allowed to continue to operate. Arc protection circuit () also provides a restart function for periodically attempting to ignite and operate the lamp. Arc protection circuit () is preferably realized using a timer integrated circuit (U) with associated discrete circuitry, and may be adapted for use with ballasts having self-oscillating or driven type inverters.

A ballast (') includes a rectifier circuit (), a boost converter (&#x2032;), an inverter (), an output circuit (), and an inverter startup circuit (). Inverter startup circuit () is coupled between boost converter () and inverter (). During operation, inverter startup circuit () provides a delay period between startup of boost converter () and startup of inverter () so that startup of inverter () is delayed until at least such time as the DC rail voltage provided by boost converter () approaches its steady-state operating level. This ensures that the ballast (&#x2032;) provides an output voltage that is sufficiently high to ignite a lamp () in a preferred manner, with little or no glow current and a fast strike time.

Ballast with inverter startup circuit

A ballast ( ) includes an inverter ( ) and a protection circuit that prevents excessive lamp-to-earth-ground fault current. The protection circuit includes a transformer ( ) and an inverter disable circuit ( ). The transformer measures a first current going out of one set of ballast output terminals ( ) and a second current going into another set of ballast output terminals ( ). In response to a substantial imbalance between the first current and the second current, inverter disable circuit ( ) terminates inverter switching. Preferably, protection circuit further includes a restart timer circuit ( ) that, following termination of inverter switching in response to a fault condition, prevents the inverter from restarting for a predetermined delay period.

Ballast with lamp-to-earth-ground fault protection circuit

A dimming control system includes a first circuit ( ) and a second circuit ( ). First circuit ( ) is coupled in series with the AC line source ( ) and receives brighten and dim commands from a user. The brighten and dim commands are communicated to second circuit ( ) by momentarily altering the AC voltage waveforms observed by second circuit ( ). Second circuit ( ) provides an adjustable output signal that is coupled to inverter circuitry within an electronic dimming ballast. The output signal is adjusted by the second circuit ( ) in dependence on the observed AC voltage waveforms.

Dimming control system for electronic ballasts

A ballast ( ) for powering a gas discharge lamp load ( ) comprises a protection circuit ( ) operable to monitor an electrical signal ( ) in the ballast and disable the ballast for at least a predetermined period of time in response to a disturbance wherein at least a portion ( ) of the electrical signal ( ) exhibits a time-rate-of-change that exceeds the time-rate-of-change of the signal during normal operation of the ballast and gas discharge lamp load. Protection circuit ( ) is capable of disabling the ballast within a response time that is less than twice the period of the electrical signal. In a preferred embodiment that is suitable for ballasts with driven-type inverters, protection circuit ( ) comprises a latching device ( ) and a triggering circuit ( ). In a preferred embodiment that is suitable for ballasts with self-oscillating type inverters, protection circuit ( ) comprises a pull-down circuit ( ) and a negative voltage source ( ).

Ballast with protection circuit for quickly responding to electrical disturbances

A ballast ( ) for powering a gas discharge lamp load includes an inverter ( ) and a protection circuit ( ) for preventing start up of the inverter ( ) in response to a ground fault condition wherein one or more of the ballast output connections ( ) is coupled to earth ground.

Ballast with protection circuit for preventing inverter startup during an output ground-fault condition

A circuit for controlling current during run-up of a high pressure discharge lamp ( ) comprises a buck converter ( ) for generating a buck current to drive the high pressure discharge lamp and a control circuit ( ) coupled to the buck converter ( ) for varying the duty cycle of the buck current during run-up is disclosed. A method for controlling current in an electronic ballast during run-up of a high pressure discharge lamp comprises steps of detecting ( ) lamp ignition, providing ( ) a buck current to drive the lamp, and varying ( ) the duty cycle of the buck current during run-up to control ( ) the current in the lamp is also disclosed.

Method and circuit for controlling current in a high pressure discharge lamp

A ballast ( ) for powering a gas discharge lamp includes a lamp-out detection circuit ( ) that quickly responds to a lamp-out condition. Lamp-out detection circuit ( ) receives a portion of the lamp current and provides a detection voltage. The detection voltage remains at a first average level while the lamp is conducting current in a normal manner, but quickly decreases below a second level if the lamp ceases to conduct current. In a preferred embodiment, ballast ( ) includes an inverter ( ) and a resonant circuit ( ) that are normally operated at a high frequency. The detection voltage is coupled to an enable input ( ) of an inverter drive circuit ( ), and the inverter ( ) is either shut off or operated in a low-power mode within less than ten high frequency cycles after occurrence of a lamp-out condition.

Ballast with fast-responding lamp-out detection circuit

A dimming control system includes a first circuit ( ) and a second circuit ( ). First circuit ( ) is coupled in series with the AC line source ( ) and receives brighten and dim commands from a user. The brighten and dim commands are communicated to second circuit ( ) by momentarily altering the AC voltage waveforms observed by second circuit ( ). Second circuit ( ) provides an adjustable dimming control voltage that is coupled to existing dimming control circuitry within an electronic dimming ballast. The dimming control voltage is adjusted by the second circuit ( ) in dependence on the observed AC voltage waveforms.

A ballast ( ) for powering a gas discharge lamp ( ) having heatable filaments ( ) includes a filament heating and protection circuit ( ) that provides preheating of the filaments, efficiently reduces the filament heating power after the lamp ignites, quickly responds to removal or failure of the lamp in order minimize power dissipation in the ballast, and operates a replaced lamp without requiring cycling of the power to the ballast. In a preferred embodiment, filament heating and protection circuit ( ) includes a transformer ( ), a switching circuit ( ), a turn-on circuit ( ), and a lamp-out detection circuit ( ).

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Barrington, IL, United States of America

John G Konopka