Method for operating a fluorescent lamp
AssigneeInfineon Technologies Austria AG
InventorMartin Feldtkeller
Life of this patent
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Abstract
A method for operating a fluorescent lamp which is connected to a series resonant circuit with a resonant circuit inductance and a resonant circuit capacitance. The method includes applying an excitation AC voltage at an excitation frequency to the series resonant circuit using a half bridge circuit, which has an output to which the series resonant circuit is coupled, and which has a first and a second switch which are alternately switched on and off on the basis of a frequency signal. A current flowing through the resonant circuit is monitored for the presence of a critical operating state. The switched-on times of the first and second switches are shortened in comparison to switched-on times which are predetermined by the frequency signal, upon detection of a critical operating state.
Claims12
A method for operating a fluorescent lamp, which is connected to a series resonant circuit having a resonant circuit inductance and a resonant circuit capacitance, the method comprising:
- applying an excitation AC voltage at an excitation frequency to the series resonant circuit using a half bridge circuit, which has an output to which the series resonant circuit is coupled, and which has a first and a second switch which are alternately switched on and off on the basis of a frequency signal;
- monitoring of a current flowing through the resonant circuit, for the presence of a critical operating state;
- and
- shortening of the switched-on times of the first and second switches in comparison to switched-on times which are predetermined by the frequency signal, on detection of a critical operating state.
A method for operating a fluorescent lamp, which is connected to a series resonant circuit having a resonant circuit inductance and a resonant circuit capacitance, the method comprising:
- applying of an excitation AC voltage at an excitation frequency to the series resonant circuit using a half bridge circuit, which has an output to which the series resonant circuit is coupled, and which has a first and a second switch;
- reducing excitation frequency for starting the fluorescent lamp;
- and
- increasing the excitation frequency, at least temporarily, when the rate of change of a peak value of the resonant circuit current is greater than a predetermined threshold value.
A method for operating a fluorescent lamp, which is connected to a series resonant circuit having a resonant circuit inductance and a resonant circuit capacitance, the method comprising:
- applying of an excitation AC voltage at an excitation frequency to the series resonant circuit using a half bridge circuit, which has an output to which the series resonant circuit is coupled, and which has a first and a second switch;
- reducing excitation frequency for starting the fluorescent lamp,
- increasing the excitation frequency, at least temporarily, when a peak value of the resonant circuit current reaches a first threshold value;
- causing a sudden phase change in the operation of the switches when the peak value of the resonant circuit current reaches a second threshold value;
- ending the operation when the peak value of the resonant circuit current reaches a third threshold value;
- and
- the first threshold value being less than the second threshold value, and the second threshold value being less than the third threshold value.
A method for operating a fluorescent lamp, which is connected to a series resonant circuit having a resonant circuit inductance and a resonant circuit capacitance, the method comprising:
- applying of an excitation AC voltage at an excitation frequency to the series resonant circuit using a half bridge circuit, which has an output to which the series resonant circuit is coupled, and which has a first and a second switch which are alternately switched on and off on the basis of a frequency signal;
- and
- determining a peak value of a current through the resonant circuit, and setting of the time for which the first and the second switch are switched on as a function of the frequency signal and the peak value.
Dependencies are inferred from the claim text.