Smoke filters
Patent 4273141 Issued on June 16, 1981. Estimated Expiration Date: 
June 16, 1998. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
June 16, 1998. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2819720 3756250 3811451 3910288 Tobacco-smoke filters Patent #: 4135523 InventorApplicationNo. 05/886399 filed on 03/14/1978US Classes:131/336, Air131/338, Having means to vary smoke flow rate131/339, Interior surface causes particular flow characteristic131/340, By use of specific filter mass131/344Occupying plural, separate, distinct zonesExaminersPrimary: Millin, V.Attorney, Agent or FirmInternational ClassesA24D 3/00 (20060101)A24D 3/04 (20060101) Foreign Application Priority Data1977-03-14 GBAbstractA tobacco smoke filter having at least one directly ventilated cavity which provides for the formation, over a region of the filter extending inwardly of its peripheral region, of a mixture of at least the major proportion of the smoke and at least a major proportion of the ventilating air entering the said cavity or cavities. The extensive and uniform mixing of smoke and ventilation air gives a satisfying smoke with a low tar count and high nicotine/tar ratio, and can be obtained with the invention due to appropriate shaping of the cavity, or asymmetric positioning of the air ventilating vents, or by means of a flow-disturbing insert mounted in the filter, or a combination of two or more of these factors. Preferably a major part of the smoke is constrained to enter the cavity at an upstream peripheral extremity thereof and air vents are also concentrated at this extremity. | |
