| 摘要 |
A ballast having a circuit for detecting and eliminating an arc condition is provided to prevent breaking of a ballast for a normal operation by operating the ballast for an igniting time and not operating a ballast under an arc state. An inverter circuit(108) is coupled between a DC bus(104) and a lamp. A control circuit(112) controls the inverter circuit(108) to provide the lamp with power, and starts an igniting period to ignite the lamp. A detection circuit(116) is connected to the inverter circuit(108), and detects a detection signal which represents an arc based on a signal of the control circuit(112). The detection circuit(116) generates a signal provided to the control circuit(112) to stop the control circuit(112) from providing the lamp with the power. A sensing circuit(118) is connected to the inverter circuit and senses an amplitude of the detection signal which represents an arc. When an amplitude of the detection signal is over a threshold value, the sensing circuit(118) generates a signal provided to the control circuit(112) to stop the control circuit(118) from providing the lamp with the power. A switching circuit(122) is coupled to the sensing circuit(118) to stop an operation of the sensing circuit(118) in response to the control circuit(112) when the control circuit(112) starts the ignition period.
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