| 摘要 |
<p>A high-voltage transformer drive circuit 12 and a high-voltage transformer 13 drive discharge tubes 1. A tube current synthesis/high pass filter circuit 15 synthesizes tube currents in the discharge tubes 1, and extracts a pulse component resulting from arc discharge from the synthesis tube current. A pulse hold circuit 16 holds the extracted pulse component for a predetermined time. A comparator 21a compares an output from the pulse hold circuit 16 with a threshold value, and outputs a signal indicating the presence or absence of the arc discharge. Upon detection of the arc discharge, a logic circuit 20 stops the operation of the high-voltage transformer drive circuit 12. Thus, arc discharge is detected with high accuracy at low cost.</p> |
