Smoking Article

Abstract

A smoking article ( 10 ) has a filter ( 20 ) located at one end, the filter comprising at least first, second and third sections ( 34,41,51 ) disposed in succession along a cylindrical axis of the smoking article. Each of the first ( 31 ) and third ( 51 ) sections includes at least one tube ( 35,55 ) running the length of the respective section, substantially parallel to the cylindrical axis of the smoking article. The second section ( 41 ) comprises material of substantially higher filtration efficiency than the tubes ( 35,55 ) of the first and third section. Ventilation ( 43 ) may be provided around the circumference of the filter in one or more zones.

1 . A smoking article having a filter located at one end, the filter comprising at least first, second and third sections disposed in succession along a cylindrical axis of the smoking article, wherein:
 each of the first and third sections includes at least one tube running the length of the respective section,   and the second section comprises filter material of substantially higher filtration efficiency than the tubes of the first and third sections.   
     
     
         2 . The smoking article of  claim 1 , wherein the at least one tube of the first section is coaxial with the at least one tube of the third section. 
     
     
         3 . The smoking article of  claim 1  or  2 , wherein at least one tube of the first section and at least one tube of the third section are coaxial with the smoking article. 
     
     
         4 . The smoking article of any preceding claim, wherein at least one tube of the first section comprises a groove in the outer circumference of the filter. 
     
     
         5 . The smoking article of any preceding claim, wherein at least one tube of the third section comprises a groove in the outer circumference of the filter. 
     
     
         6 . The smoking article of any preceding claim, wherein the at least one tube of the first section has a length in the range 4-15 mm. 
     
     
         7 . The smoking article of any preceding claim, wherein the at least one tube of the first section has a diameter in the range 0.1-3 mm. 
     
     
         8 . The smoking article of  claim 7 , wherein the at least one tube of the first section has a diameter in the range 0.5-1.5 mm. 
     
     
         9 . The smoking article of any preceding claim, wherein the at least one tube of the third section has a length in the range 4-15 mm. 
     
     
         10 . The smoking article of any preceding claim, wherein the at least one tube of the third section has a diameter in the range 0.1-3 mm. 
     
     
         11 . The smoking article of  claim 10 , wherein the at least one tube of the third section has a diameter in the range 0.5-1.5 mm. 
     
     
         12 . The smoking article of any preceding claim, wherein the tubes are hollow. 
     
     
         13 . The smoking article of any preceding claim, wherein said first filter section other than said at least one tube comprises filter material. 
     
     
         14 . The smoking article of  claim 13 , wherein the filter material of the first filter section has a lower filtration efficiency than the filter material of the second filter section. 
     
     
         15 . The smoking article of any preceding claim, wherein said third filter section other than said at least one tube comprises filter material. 
     
     
         16 . The smoking article of  claim 15 , wherein the filter material of the third filter section has a higher filtration efficiency than filter material of the first filter section. 
     
     
         17 . The smoking article of any preceding claim, wherein ventilation holes are provided on the outside of the second filter section. 
     
     
         18 . The smoking article of any preceding claim, wherein ventilation holes are provided on the outside of the third filter section. 
     
     
         19 . The smoking article of any preceding claim, wherein the filter comprises additional pairs of filter sections in succession along a cylindrical axis of the smoking article after said third section, wherein each pair of sections comprises:
 a first additional section including at least one tube running the length of the first additional section, substantially parallel to the cylindrical axis of the smoking article;   a second additional section comprising filter material of substantially higher filtration efficiency than the at least one tube of the first additional section.   
     
     
         20 . The smoking article of any preceding claim, whereby in use:
 the exit of the at least one tube in the first section is blocked after a first amount of smoking; and   the entrance of the at least one tube in the third section is blocked after a further amount of smoking.   
     
     
         21 . The smoking article of any preceding claim wherein the tubes run substantially parallel to the cylindrical axis of the smoking article. 
     
     
         22 . A filter for use in the smoking article of any preceding claim. 
     
     
         23 . A filter for a smoking article, comprising a generally cylindrical filter body including first, second and third filter sections disposed in succession along the body each of the first and third sections includes at least one tube running the length of the respective section and the second section comprises filter material of substantially higher filtration efficiency than the tubes of the first and third sections.