| 摘要 |
A filter for a cigarette includes a porous filter rod circumscribed by an air impermeable wrapper and ventilation grooves embedded in the wrapped filter rod which extend from one end of the filter rod a preselected distance generally longitudinally thereof. A plurality of ventilation air flow apertures are formed through the wrapper. Some of the air flow apertures are located in the grooves and others of the air flow apertures are formed in the area of the wrapper outside of the grooves. An air impermeable tipping material circumscribes the wrapped filter rod. The tipping material is formed with a plurality of ventilation air flow apertures therethrough such that each ventilation air flow aperture through the tipping material is in substantial registration with a different one of the ventilation air flow apertures formed through the wrapper. In addition, a method for making the above described filter includes the steps of forming a generally cylindrical filter rod of porous material; with a circumscribing air impervious wrapper material, embedding at least one groove in the wrapped filter rod extending from and open to one end of the filter a preselected distance generally longitudinally of the filter rod less than the length of the filter rod; circumscribing the grooved filter rod with an impermeable tipping material; concurrently forming perforations through the tipping paper and underlaying wrapper material in a region outside the at least one groove; and concurrently forming at least one perforation in the tipping material over the at least one groove. |
