| 摘要 |
A conventional HEPA (high efficiency particulate air) filter is provided with a ionizer at its air inlet face to enhance its efficiency. The filter comprises a non-conductive fibrous filter medium sheet formed in a zig-zag or accordian fold. Within each fold of the filter medium is there located a conductive spacer so that the accordian folds are supported and substantially evenly spaced throughout the filter. By virtue of the accordian fold of the filter medium sheet, a series of spacers, forming a first set thereof, each has one of its longitudinal edges exposed at the air inlet face of the filter and the other of its longitudinal edges covered at the air discharge face of the filter. The remaining spacers constitute a second set thereof, each having one of its longitudinal edges exposed at the air discharge face of the filter and the other of its longitudinal edges covered at the air inlet face of the filter. The spacers of the first and second sets alternate, one adjacent the other. The ionizer comprises a plurality of wire-like electrodes and grounded plate-like electrodes arranged alternately and in parallel spaced relationship in a plane perpendicular to the spacers and are positively charged by connection to a high voltage, low current source. The ionizer electrodes are located within charging range of the first set of spacers which are charged by ion flow from the corona of the ionizing electrodes. To create a field between the first set of spacers and the second set of spacers, the spacers of the second set are connected together and to ground. In another embodiment the ionizer is located remotely with respect to one or more HEPA filters and functions to charge the particulate material. A single wire-like electrode is located at each HEPA filter to charge one of its first and second sets of spacers, the other of its first and second sets of spacers being connected to ground.
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