Method of and apparatus for ascertaining parameters of cigarette paper and the like

Abstract

The invention relates to a method of and to an apparatus for ascertaining at least one parameter of cigarette paper or the like, such as a running web of cigarette paper at least one side of which carries or should carry longitudinally spaced-apart coatings, e.g., consisting of silicate or cellulose and suitable to serve as so-called burning or combustion stops. A source of electromagnetic radiation cooperates with a polarizer to direct radiation against one side of the running web at an angle of between about 0° and 75° to the plane of the web at the locus of impingement of radiation. The radiation which has penetrated through the web is measured by a photosensitive detector which transmits corresponding signals to an evaluating arrangement serving to ascertain one or more characteristics of the coatings.

What is claimed is:  
     
         1 . A method of ascertaining at least one parameter of cigarette paper, comprising the steps of: 
 directing against one side of the cigarette paper at least one beam of electromagnetic radiation at an incidence angle α of between 0° and 75° whereby a portion of said radiation issues from and at the other side of the cigarette paper;    measuring the issuing radiation;    and ascertaining said at least one parameter as a function of said issuing radiation.    
     
     
         2 . The method of  claim 1 , wherein said angle α is between about 5° and 45°.  
     
     
         3 . The method of  claim 1 , wherein said angle α is between about 10° and 20°.  
     
     
         4 . The method of  claim 3 , wherein said angle α is about 15°.  
     
     
         5 . The method of  claim 1 , further comprising the step of detecting said radiation issuing from and at the other side of the cigarette paper at a predetermined angle β with respect to the other side of the cigarette paper.  
     
     
         6 . The method of  claim 5  wherein said angle β is between about 45° and 90°.  
     
     
         7 . The method of  claim 6 , wherein said angle β is between about 70° and 90°.  
     
     
         8 . The method of  claim 1 , wherein said electromagnetic radiation has a predetermined polarized condition.  
     
     
         9 . The method of  claim 8 , wherein said electromagnetic radiation is linearly polarized parallel to the one side of the cigarette paper.  
     
     
         10 . The method of  claim 1 , further comprising the step of advancing the cigarette paper in a predetermined direction, said at least one parameter involving the presence of essentially periodical coatings provided at least at one of said sides of the cigarette paper and entailing essentially periodical changes of intensity of radiation issuing from the cigarette paper at a locus of impingement of electromagnetic radiation against said one side of the advancing cigarette paper.  
     
     
         11 . The method of  claim 10 , wherein said determining step includes determining the periods of said changes of radiation and said ascertaining step includes comparing the determined periods of said changes of radiation with a predetermined period.  
     
     
         12 . The method of  claim 11 , further comprising the step of ascertaining the extent of said changes of radiation and said predetermined period includes an interval of average value of intensity of radiation which is characteristic of at least one constituent of the material of said coating.  
     
     
         13 . Apparatus for ascertaining at least one parameter of cigarette paper, comprising; 
 a source of electromagnetic radiation;    means for directing a beam of radiation from said source against one side of the cigarette paper at an angle α of between about 0° and 75° whereby a portion of such radiation issues from and at the other side of the cigarette paper;    detector means arranged to measure the issuing radiation; and    means for ascertaining the at least one parameter of cigarette paper as a function of said issuing radiation.    
     
     
         14 . The apparatus of  claim 13 , wherein said angle α is between about 5° and 45°.  
     
     
         15 . The apparatus of  claim 13 , wherein said angle α is between about 10° and 20°.  
     
     
         16 . The apparatus of  claim 15 , wherein said angle α is about 15°.  
     
     
         17 . The apparatus of  claim 13 , wherein said detector means is positioned to intercept radiation issuing from and at the other side of the cigarette paper at a predetermined angle g with respect to the cigarette paper.  
     
     
         18 . The apparatus of  claim 17 , wherein said angle β is between about 45° and 90°.  
     
     
         19 . The apparatus of  claim 17 , wherein said angle β is between about 70° and 90°.  
     
     
         20 . The apparatus of  claim 13 , further comprising means for polarizing the radiation issuing from said source before the radiation reaches the cigarette paper.  
     
     
         21 . The apparatus of  claim 20 , wherein said polarizing means is arranged to polarize the radiation issuing from said source in parallel to said one side of the cigarette paper.  
     
     
         22 . The apparatus of  claim 13 , further comprising means for advancing the cigarette paper along a predetermined path, said detector means being arranged to monitor the intensity of radiation issuing from the cigarette paper and said at least one parameter including the presence of essentially periodical coatings provided at least at one of said sides of the cigarette paper in said path and entailing essentially periodical changes of intensity of radiation reaching said detector means subsequent to penetration through the web in a predetermined portion of said path.  
     
     
         23 . The apparatus of  claim 22 , wherein said ascertaining means comprises a memory operatively associated with said detector means and arranged to store a predetermined period of changes for comparison with changes represented by the radiation determined by said detector means.  
     
     
         24 . The apparatus of  claim 23 , wherein said memory includes a table denoting the extent of said changes of radiation and said predetermined period includes an interval of average value of intensity of radiation which is characteristic of at least one constituent of the material of said coatings.