| 摘要 |
PROBLEM TO BE SOLVED: To enable to restrain degradation of static-eliminating function as well as to attain a high-precision ion balance. SOLUTION: A positive and a negative ion detecting electrodes 4, 5, each arrayed close to a positive and a negative discharge electrodes 2, 3 detects a positive and a negative ion currents respectively, which are converted into an analog voltage with a current/voltage conversion circuit 6, 7, and then, into a digital one with an A/D conversion circuit 8, and both ions are compared by a microcomputer 9. Digital control signals are outputted so as to balance the positive and negative ions, and D/A converted with D/A conversion circuits 10, 11 and make a direct-current high voltage of positive and negative high- voltage generating circuits 12, 13 variable, and at the same time, decreased amount of positive and negative ions detected is measured by the microcomputer 9, in correspondence with which, the digital control signals are outputted for increasing ion current by the decreased amount, changing the direct-current high voltage of the positive and negative high-voltage generating circuits 12, 13.
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