Patent ID: 8353298

Claim:
A smoking article comprising: a tobacco rod adapted to produce mainstream smoke; a filter having an upstream end portion and a downstream end portion, said filter arranged to receive mainstream smoke at said upstream end portion, said filter comprising: an upstream filter plug segment at said upstream end portion; a downstream filter plug segment at said downstream end portion; a flow constricting segment consisting of a tubular portion, a single transverse plate, an upstream cavity and a downstream cavity, said upstream cavity and said downstream cavity having an equal volume and defined by said tubular portion and said single transverse plate, said flow constricting segment provided at a location adjacent said downstream filter plug segment, said flow constricting segment adapted to direct mainstream smoke at a relatively high velocity, compared to the velocity of the mainstream smoke through the tobacco rod, toward an adjacent region of said downstream filter plug segment, said flow constricting segment comprising at least one opening in the single transverse plate, said at least one opening spaced away from an end face of the downstream filter plug segment by at least about 1 mm; and, tipping paper attaching said filter with said tobacco rod and including an air-admissing ventilating zone superposed with the downstream filter plug segment.