Diagnosis circuit apparatus and lamp ballast circuit using the same
AssigneeFairchild Korea Semiconductor Ltd.
InventorsGye-Hyun Cho, Young-Sik Lee
Life of this patent
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Abstract
The present invention relates to a diagnostic device and a lamp ballast circuit. The lamp ballast circuit includes a first power switch, a second power switch, a lamp driven according to switching operations of the first and second power switches, a controller for controlling the switching operations of the first and second power switches, and a diagnostic device. The diagnostic device senses a voltage waveform applied to the lamp to determine an end of lamp life (EOLL) condition and an over-voltage, senses a filament voltage of the lamp to determine a filament connection state of the lamp, and determines an over-voltage of a voltage applied to the controller.
Claims26
A lamp ballast circuit for driving a lamp driven according to switching operations of first and second power switches, the lamp ballast circuit comprising:
- a controller configured to control a switching operation of the first and second power switches;
- and
- a diagnostic device configured to sense a voltage applied to the lamp to determine an end of lamp life (EOLL) condition and an over-voltage applied to the lamp, to sense a filament voltage of the lamp to determine a filament connection state of the lamp, and to sense an over-voltage of a voltage applied to the controller,
- wherein the diagnostic device is configured to control the controller such that the switching operation is not performed when at least one of the end of lamp life (EOLL) condition, the over-voltage applied to the lamp, an abnormal state of the filament connection state, and the over-voltage of the voltage occurs.
A diagnostic device for diagnosing states of a lamp and a controller configured to control the lamp, the diagnostic device configured to sense a phase of a voltage waveform applied to the lamp, to rectify the voltage waveform, to separate the rectified voltage waveform into a first phase signal and a second phase signal, the diagnostic device comprising:
- an end of lamp life (EOLL) condition determining unit configured to use a proportional value of the first phase signal and a proportional value of the second phase signal to determine the end of lamp life (EOLL) condition;
- an over-voltage determining unit configured to compare the first and second phase signals to a first reference voltage to determine an over-voltage of the lamp;
- a filament stage determining unit configured to compare a first voltage corresponding to a filament voltage of the lamp to a second reference voltage to determine a filament connection state;
- and
- an input voltage detector configured to compare a second voltage corresponding to a voltage of a voltage applied to the controller to a third reference voltage to determine whether the voltage of the voltage applied to the controller is the over-voltage.
Dependencies are inferred from the claim text.