Air filter formed by slit and expanded layers of electrostatically enhanced material

摘要

An air filter including a plurality of air-pervious sheets of electret filtration material. The sheets are disposed in a parallel relationship to form a stack of sheets, and each of the sheets has a plurality of slits formed therein for subsequent expanding to form openings. The stack is connected together at opposing ends, such as by bonding. The sheets can be pleated by mounting in a frame. The frame has opposing ends to which the opposing ends of the stack are mounted. The filter media initially has no frame and is not pleated, but is in a flat pad form that is expanded to be installed into a frame. The frame is then mounted in an appliance, such as a room air filter. When the filter is inserted into the filter housing it is expanded and can take a pleated form.