| 摘要 |
<p>PURPOSE:To prolong the life of a filter, by intermittently charging external electricity to enhance the collecting efficiency of the air filter up to a predetermined range and to hold the collecting efficiency of the air filter in the predetermined range over a long time. CONSTITUTION:A particle-charging filter or sensor 5 provided with a particle- charging means 3 is attached to the front part of an air filter 2 having dielectric body as a filter 1. DC high voltage is applied to the particle-charging means 3 to charge floating dust or the like in air with electricity. The floating particles in an air stream flowing into the high electric field of the means 3 are strongly charged with positive electricity, so that a fibrous material constituting the dielectric filter 1 is affected at the downstream side is affected by image-forming action. The lower and upper limits of the collecting efficiency necessary in response to the use of the air filter are set to enable to intermittently charge external electricity.</p> |
