| 摘要 |
A cigarette filter ventilated via passages (56) and tipping wrap (14) perforations (16), the filter presenting initially relatively low pressure drop (54, 42) and relatively high pressure drop (40, 42) paths for the passage of smoke therethrough, the arrangement being such that in use the initial preferential passage of smoke via the low pressure drop path or paths causes progressive block thereof so that the passage of smoke via the high pressure drop path or paths and the degree of air ventilation are increased. The axially elongate filter core (2) may have passages (54) which are open at one end of the core, extend therefrom only partially towards the other end (50) of the core, and are in smoke- flow communication with the core via means (55) progressively blockable by the passage of unfiltered tobacco smoke therethrough. <IMAGE> |
