| 摘要 |
PURPOSE: A protection circuit is provided to protect a human body from electrical shock and prevent damages of cold cathode ray tube. CONSTITUTION: An inverter comprises a cold cathode ray tube(3) which turns on by the high voltage output from an external source; a cold cathode ray tube driver IC(1) for outputting a driver signal of pulse type, detecting whether the cold cathode ray tube opens, and controls output by detecting the current flowing through the cold cathode ray tube; a transformer(2) for boost transforming the AC power output from the cold cathode ray tube driver IC and outputting a high voltage to the cold cathode ray tube; an output current detector circuit(4) for detecting the current flowing through the cold cathode ray tube and applying the detected current to the cold cathode ray tube driver IC; an open lamp protection circuit(5) connected to the line interconnecting the output of the transformer and the cold cathode ray tube, wherein the open lamp protection circuit senses the current being applied to the cold cathode ray tube and informs whether the cold cathode ray tube is open to the cold cathode ray tube driver IC; and a body contact protection circuit(100) for detecting whether a human body contacts a high voltage by sensing the voltage being input to the open lamp protection circuit, and stopping the operation of the inverter by informing the body contact to the cold cathode ray tube driver IC if the human body contacts the high voltage.
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