Controlling a Lamp Ballast

A method, comprising:

• generating a detector signal that depends on a power supply voltage and a presence of a lamp;
• monitoring an operating parameter of a lamp ballast coupled to the lamp;
• causing the lamp ballast to enter a low power consumption state responsive to the operating parameter indicating an outage of the power supply voltage;
• monitoring the detector signal during the low power consumption state;
• and
• if, during the low power consumption state, the detector signal indicates that the power supply voltage is present and the lamp is present, and if an interval between a beginning of the low power consumption state and the detection of the power supply voltage is shorter than a predetermined standby time, causing the lamp ballast to change from the low power consumption state to a lamp operating state without entering a preheat state, or to the preheat state for a first preheat time and then to the lamp operating state.

An apparatus, comprising:

• means for monitoring an operating parameter of the lamp ballast and conversion of the lamp ballast to a low power consumption state responsive to the operating parameter decreasing below a specified limiting value;
• means for monitoring a detector signal during the low power consumption state;
• and
• means for causing the lamp ballast to change from the low power consumption state to a lamp operating state without entering a preheat state, or to the preheat state for a first preheat time and then to the lamp operating state, if the detector signal indicates during the low power consumption state that a power supply voltage is present and a lamp connected to the lamp ballast, and if an interval between a beginning of the low power consumption state and the detection of the power supply voltage is shorter than a predetermined time interval.

An apparatus, comprising:

• a converter having an input, and having an output configured to be connected to a lamp, the converter being configured to be any of a low power consumption state, a preheat state, and a lamp operating state;
• a transformer stage having an input configured to receive a power supply voltage and an output coupled to the input of the converter;
• and
• a drive circuit configured to:
• drive the transformer stage and the converter, to monitor an operating parameter of the apparatus,
• cause the converter to enter the low power consumption state responsive to the operating parameter,
• monitor, after causing the converter to enter the low power consumption state, the operating parameter cyclically during a monitoring time, and
• cause the converter to enter the lamp operating state without a preheat state or to enter the lamp operating state after a preheat state having a first preheat time, responsive to the cyclically monitored operating parameter indicating that a power supply voltage is present and if an interval since the beginning of the state of low power consumption is shorter than a predetermined standby time.