US Patent 10368575 Smoking article with a mouth end cavity and ventilation

A smoking article (10) comprises a tobacco rod (12) and a filter (14) connected to the tobacco rod (12). The filter (14) comprises a first filter segment (20) and a hollow tube segment (22) downstream of the first filter segment (20). The hollow tube segment (22) defines a cavity (24) at the mouth end of the filter (14) providing an unrestricted flow channel that extends from the downstream end of the first filter segment (20) to the mouth end of the filter (14). The length of the hollow tube segment (22) is at least about 25 percent of the overall filter length. Further, the smoking article (10) comprises a ventilation zone (26) comprising at least one circumferential row of perforations provided at a location around the first filter segment (20).