| 摘要 |
PROBLEM TO BE SOLVED: To electrify stray dust for preventing its adhesion and to satisfactorily keep the balance of positive and negative ions generated when a high frequency is used by applying an AC or DC high voltage to needle-like discharge electrodes, and feeding the air ionized by a corona discharge. SOLUTION: A compact thin, lightweight, and low-noise piezoelectric transformer 4 capable of simply obtaining a high-voltage, high-frequency output is preferably stored in a high-voltage power supply 3, a high frequency of 10-120 kHz is applied to needle electrodes 1 from it via a cable 2, and electrified positive and negative ions are discharged with good balance. This is superior to the high-voltage power supply of a wire-wound transformer. A dust adhesion prevention object is electrified to the same polarity as that of the ionized air, and the adhesion of dust may be prevented by electric repulsion. This dust adhesion preventing unit is preferably provided on the air duct of the cooling fan of an image device provided with a filter, the cooling fan, a lamp, and a lens, or a liquid crystal and deflection filter, and the adhesion of dust into a liquid crystal projector can be prevented easily.
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