Osram Sylvania Inc.

Osramsylavania Inc.

Himamshu V Prasad

John G Konopka

Shashank Bakre

Naveen Yadlapalli

Sameer Sodhi

Young G Kang

Warren Moscowitz

Shashank S Bakre

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

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.

A ballast ( ) having an inverter ( ) and a direct current blocking capacitor ( ) coupled in series with a ballast output ( ) includes a control circuit ( ) for providing adaptive end-of-lamp-life protection. During operation, control circuit executes the steps of measuring ( ) and storing ( ) a reference value for the voltage across the DC blocking capacitor ( ), monitoring ( ) the voltage across the DC blocking capacitor ( ), and protecting ( ) the inverter and lamp sockets in response to the voltage across the DC blocking capacitor departing from the reference value by more than a predetermined threshold amount.

Ballast with adaptive end-of-lamp-life protection

A dimming ballast ( ) for a high-intensity discharge lamp ( ) includes an ignitor ( ), a control circuit ( ), and a dimming interface ( ) for connection to an external dimming controller ( ). Following lamp replacement ( ), external dimming controller ( ) receives a user relamp command and, in response, sends a special relamp signal to dimming interface ( ). In response to the special relamp signal, dimming interface ( ) communicates with control circuit ( ), which directs ignitor ( ) to provide high voltage pulses for igniting the replaced lamp. In an alternative embodiment, an external control device such as a triac dimmer ( ) receives a user relamp command following lamp replacement and, in response, sends a special relamp signal to a control circuit ( ), which directs ignitor ( ) to provide high voltage pulses for igniting the replaced lamp.

High-intensity discharge lamp ballast with live relamping feature

A ballast ( ) and method for regulating power in a high pressure discharge lamp ( ) is disclosed. In a preferred embodiment, ballast ( ) comprises a microcontroller ( ), a buck converter ( ), and an inverter ( ). Microcontroller ( ) monitors a signal representative of the lamp voltage and sets a current in the lamp based upon the monitored signal via control of a buck current provided by the buck converter ( ). A method for regulating power in a high pressure discharge lamp is also described. The method comprises steps of detecting ( ) a voltage at the lamp and setting ( ) a current in the lamp based upon the detected voltage.

Method and circuit for regulating power in a high pressure discharge lamp

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.

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Rolling Meadows, IL, United States of America

Himamshu V Prasad