a preferred embodiment provides a smoking article 10 comprising a tobacco rod 12 and a filter 14 which are joined together by a tipping paper 16 . the filter 14 comprises a first filter segment 20 adjacent the tipped end 21 of the tobacco rod 12 . preferably , the first filter segment 20 is constructed of a fibrous cellulose acetate ( ca ) tow or a plug of cellulose acetate tow laden with activated carbon particles ( cot ), beads or other absorbents . the filter 14 further comprises a second filter segment 22 in downstream relation to the first segment 20 ( in the sense of direction that mainstream smoke is drawn through the filter 14 during a puff ). the second filter segment 22 includes a hollow frusto - conical upstream portion 24 and a fluted downstream portion 26 . the fluted downstream section can include one or more planar or non - planar walls defining voids 28 . the diameter of the second filter segment 22 is approximately equal to that of the filter 14 , such that the outer peripheries of portions 24 , 26 and any ( optional ) plug wrap 29 are adjacent ( abut ) the tipping paper 16 . the second filter segment 22 further includes one or more , preferably at least 2 orifices 34 at locations about the frusto - conical portion 24 that communicate the interior space 25 of the upstream frusto - conical portion 24 with one or more of the flutes ( or “ voids ”) 28 defined between the downstream fluted portion 26 and adjacent portions of a plug wrap 29 and / or the tipping paper 16 . preferably , the filter 14 further comprises a mouthpiece filter segment 30 at the buccal end of the filter 14 and one or more rows of ventilation holes 32 . the ventilation holes 34 are at a location along the filter 14 downstream of the orifices 34 and preferably are in superposed relation to the flutes (“ voids ”) 28 of the downstream segment portion 26 . during a puff on the cigarette 10 , mainstream smoke is drawn from the tobacco rod 12 into the filter 14 through the first segment 20 and then into the space 25 and through the orifices 34 of the upstream portion 24 of the second filter segment 22 . upon entering the flutes 28 of the downstream segment portion 26 , the mainstream smoke is mixed with ventilation air that is drawn through the ventilation holes 32 . the ventilated mainstream smoke is then drawn through the mouthpiece filter and out the cigarette 10 . in the preferred embodiment , the downstream filter segment is formed to establish four ( 4 ) flutes 28 , whereas three ( 3 ), two ( 2 ) or one ( 1 ) flutes might be arranged instead ( 28 ′, 28 ″ in fig3 ). more than four flutes are also a possibility . a preferred material for construction of the second filter segment 22 is a heavy wrapping paper such as non - permeable 0 . 006 inch thick paper similar to that used in a parliament recessed filter cigarette or stiff porous plug wrap . however , other materials may be used such as polyethylene , polypropylene and the like , non - woven stable fibers , and / or extruded open - celled foamed material , e . g ., cellulose acetate filamentary tow material . for example , the second filter segment can be made from high density polyethylene and / or polypropylene . the first filter segment 20 prevents tobacco particles and the like from clogging the orifices 34 of the second filter segment 22 . preferably , it is constructed of cellulose acetate tow of low particulate efficiency , e . g ., cellulose acetate tow of 8 . 0 denier per filament and 35000 total denier . the mouthpiece filter segment 30 is preferably constructed from cellulose acetate tow and is of low particulate efficiency , e . g ., cellulose acetate tow of 8 . 0 denier per filament and 35000 total denier . the ventilation holes 32 are preferably laser perforations made by known online laser perforation techniques . however , pre - perforated tipping paper can also be used . the orifices 34 may be located and aligned relative to the flutes 28 such that they promote mixing of mainstream smoke with ventilation air along the flutes 28 . referring now to fig2 , in addition or in the alternative , the orifices 34 may be arranged to direct mainstream smoke toward adjacent surface regions 125 of the downstream fluted portion such that impaction of mainstream smoke is promoted to thereby remove a larger contingent of particles of tar from the mainstream smoke and to increase smoke particle filtration efficiency under higher flow rate or larger puff volume . the cigarette 10 and the layout of its filter 14 are conducive to high speed manufacturing techniques including those taught in u . s . pat . no . 4 , 357 , 950 , hereby incorporated by reference in its entirety . referring now to fig3 , a method of manufacturing the cigarette 10 includes production of a continuous hollow tube 50 which is fed through a set of crimping wheels 54 whose perimeters form at their nip the aforementioned downstream fluted portions 26 of the second filter segments 22 . optionally , a plug wrap 29 can be added using a garniture 56 or other expedient . a laser 58 is employed to establish the orifices 34 at location ( s ) about the frusto - conical portion 24 of the second filter segment 22 . a knife 60 severs the continuous , crimped rod into 2 - up plugs of second filter segments 22 , 22 ′, which are combined with 2 - up plugs of first filter segments 20 , 20 ′, which are severed in the middle of the 2 - up second filter segments 22 , 22 ′ and combined with 2 - up plugs of mouthpiece filter segments 30 , 30 ′ to form 2 - up filters 14 , 14 ′. pairs of tobacco rods 12 , 12 ′ are tipped with 2 - up filters 14 , 14 ′ and tipping paper 16 to form 2 - up cigarettes , which are severed and laser perforated to establish ventilation holes 32 . preferably , the size of the orifices 34 can range from 0 . 4 to 0 . 8 mm in diameter and are sized to produce a desired range of resistance to draw , e . g ., at least 50 mm water or greater , preferably 60 to 90 mm water , measured at a flow rate of 1050 cc / min ; whereas the ventilation holes 32 are of such size and number so as to produce ventilation in the range of approximately 45 to 90 %, more preferably in the range of approximately 50 to 80 %. with such filter and cigarette construction , there is achieved a mass - producible filter and smoking article of elevated ventilation with acceptable levels of rtd and with desirable organoleptic qualities of its smoke . in another embodiment , when the second filter segment is constructed of polyethylene , polypropylene , and the like , the second filter segment can be fabricated using injection molding in either individual pieces or in multiples of 2 , 4 or 6 ( 2 - up , 4 - up or 6 - up ) instead of the continuous process using a crimping wheel . the 2 - up , 4 - up or 6 - up second filter segments fabricated by injection molding can be wrapped in a plug wrap of desired thickness and mechanical strength when combined with the upstream and / or downstream plugs of filter material such that the outer peripheries of the frusto - conical portion and the fluted portion and any optional plug wrap are adjacent the tipping paper . the preferred embodiments are merely illustrative and should not be considered restrictive in any way . the scope of the invention is given by the appended claims , rather than the preceding description , and all variations and equivalents which fall within the range of the claims are intended to be embraced therein .
a smoking article having a filter segment that establishes both a desired resistance to draw and a mixing of mainstream smoke with ventilation air . the filter segment includes a fluted portion , a frusto - conical portion and axially extending orifices establishing fluid communication between the frusto - conical portion and voids between one or more walls of the fluted portion .