Packing machine and method and device for controlling cigarette tips

Abstract

A method and device for controlling tips of cigarettes fed in groups along a feed path through a control station; the device has a number of sensors, each of which induces a stationary microwave field to determine correct fill of the tips of cigarettes travelling through the stationary microwave field.

1 ) A device for controlling the fill of cigarette tips, comprising conveying means ( 6 ) for feeding a group ( 7 ) of cigarettes ( 4 ) along a feed path (P) through a control station ( 8 ); at least one sensor ( 13 ) located at the control station ( 8 ), and which emits a detection signal as a function of the fill of a tip ( 3 ) of a cigarette ( 4 ); and a computer ( 22 ) connected to the sensor ( 13 ), and which compares the detection signal with a reference data item, and emits an error signal as a function of the comparison between the reference data item and the detection signal; the device being characterized in that the sensor ( 13 ) comprises a microwave sensor ( 13 ) for producing a microwave field ( 14 ) of a substantially given shape, and through which the tip ( 3 ) of the cigarette ( 4 ) travels in use; the detection signal being a function of the density of the tip ( 3 ) of the cigarette ( 4 ).  
   
   
       2 ) A device as claimed in  claim 1 , wherein the computer ( 22 ) determines a detection data item as a function of the detection signal, and emits the error signal when the difference between the detection data item and the reference data item exceeds a threshold value.  
   
   
       3 ) A device as claimed in  claim 1 , wherein the microwave sensor ( 13 ) defines a planar microwave field ( 14 ).  
   
   
       4 ) A device as claimed in  claim 1 , wherein the conveying means ( 6 ) convey the groups ( 7 ) of cigarettes ( 4 ) crosswise to the cigarettes ( 4 ).  
   
   
       5 ) A device as claimed in  claim 1 , wherein the sensor ( 13 ) emits a respective detection signal for each cigarette ( 4 ) whose tip ( 3 ) travels through the microwave field ( 14 ).  
   
   
       6 ) A device as claimed in  claim 1 , and comprising at least three sensors ( 13 ), each for controlling tips ( 3 ) of cigarettes ( 4 ) in a respective row ( 12 ) of cigarettes ( 4 ) in each group ( 7 ) of cigarettes ( 4 ); each group ( 7 ) of cigarettes ( 4 ) comprising three superimposed rows ( 12 ) of cigarettes ( 4 ).  
   
   
       7 ) A device as claimed in  claim 1 , wherein the detection signal comprises a response curve (C i , C ii , C iii ) having a peak detected frequency (A i ), and a detected amplitude (B i ) at mid peak height; the peak detected frequency (A i ) and the detected amplitude (B i ) being functions of the density and humidity of the tip ( 3 ) of the cigarette ( 4 ); and the computer ( 22 ) comparing the detection signal with the reference data item by processing the peak detected frequency (A i ) and the detected amplitude (B i ).  
   
   
       8 ) A device as claimed in  claim 7 , wherein the computer ( 22 ) determines a detected density of the tip ( 3 ) of the cigarette ( 4 ) as a function of the peak detected frequency (A i ) and the detected amplitude (B i ).  
   
   
       9 ) A device as claimed in  claim 8 , wherein the computer ( 22 ) determines a detected humidity of the tip ( 3 ) of the cigarette ( 4 ) as a function of the peak detected frequency (A i ) and the detected amplitude (B i ), and determines the detected density as a function of the detected humidity and the peak detected frequency (A i ) or the detected amplitude (B i ).  
   
   
       10 ) A device as claimed in  claim 7 , wherein the computer ( 22 ) determines a first deviation (A Δ ) between the peak detected frequency (A i ) and a reference frequency (A R ), determines a second deviation (B Δ ) between the detected amplitude (B i ) and a reference amplitude (B R ), and determines a detected humidity of the tip ( 3 ) of the cigarette ( 4 ) as a function of the first and second deviation (A Δ , B Δ ); the reference frequency (A R ) and the reference amplitude (B R ) being the peak frequency and mid-peak-height amplitude respectively of a reference curve (C R ) of a reference signal obtained with substantially no objects in the microwave field ( 14 ).  
   
   
       11 ) A device as claimed in  claim 10 , wherein the computer ( 22 ) determines a detected humidity of the tip ( 3 ) of the cigarette ( 4 ) as a function of the first and second deviation (A Δ , B Δ ), and determines the detected density as a function of the detected humidity and the first or second deviation (A Δ , B Δ ) .  
   
   
       12 ) A device as claimed in  claim 11 , wherein the computer ( 22 ) determines the detected humidity of the tip ( 3 ) of the cigarette ( 4 ) according to the following equation:  
     
       
         
           
             φ 
             = 
             
               arctg 
               ⁢ 
               
                   
               
               ⁢ 
               
                 
                   A 
                   Δ 
                 
                 
                   B 
                   Δ 
                 
               
             
           
         
       
     
     where φ is directly proportional to the detected humidity, A Δ  indicates the modulus of the first deviation, and B Δ  indicates the modulus of the second deviation.  
   
   
       13 ) A device as claimed in  claim 12 , wherein the computer ( 22 ) determines the detected density of the tip ( 3 ) of the cigarette ( 4 ) using test curves (T), each of which is predetermined experimentally at a respective given constant humidity; and each curve (T) describes the density pattern as a function of the ratio A Δ /A i .  
   
   
       14 ) A device as claimed in  claim 1 , wherein the computer ( 22 ) breaks the detection signal down into two components (A i , B i ), each of which is a function of the humidity and density of the tip ( 3 ) of the cigarette ( 4 ); determines the detected humidity as a function of the two components (A i , B i ); and determines the detected density as a function of the detected humidity and at least one of the two components (A i , B i ).  
   
   
       15 ) A method of controlling the fill of cigarette tips, the method comprising conveying a group ( 7 ) of cigarettes ( 4 ) along a feed path (P) through a control station ( 8 ); determining a detection signal as a function of the fill of a single tip ( 3 ) of a cigarette ( 4 ); and comparing the detection signal with a reference data item, and emitting an error signal as a function of the comparison between the detection signal and the reference data item; the method being characterized in that the detection signal is determined by producing a microwave field ( 14 ) of substantially given shape, through which microwave field ( 14 ) the tip ( 3 ) of the cigarette ( 4 ) travels; the detection signal being a function of the density of the tip ( 3 ) of the cigarette ( 4 ).  
   
   
       16 ) A method as claimed in  claim 15 , wherein an error signal is emitted when the difference between a detection data item, determined as a function of the detection signal, and the reference data item exceeds a threshold value.  
   
   
       17 ) A method as claimed in  claim 15 , wherein the microwave field ( 14 ) is a planar microwave field ( 14 ).  
   
   
       18 ) A method as claimed in  claim 15 , wherein the cigarettes ( 4 ) are conveyed transversely through the control station ( 8 ).  
   
   
       19 ) A method as claimed in  claim 15 , wherein the detection signal comprises a response curve (C i , C ii , C iii ) having a peak detected frequency (A i ), and a detected amplitude (B i ) at mid peak height; the peak detected frequency (A i ) and the detected amplitude (B i ) being functions of the density and humidity of the tip ( 3 ) of the cigarette ( 4 ); and the detection signal being compared with the reference data item by processing the peak detected frequency (A i ) and the detected amplitude (B i ).  
   
   
       20 ) A method as claimed in  claim 19 , wherein a detected density of the tip ( 3 ) of the cigarette ( 4 ) is determined as a function of the peak detected frequency (A i ) and the detected amplitude (B i ).  
   
   
       21 ) A method as claimed in  claim 20 , wherein a detected humidity of the tip ( 3 ) of the cigarette ( 4 ) is determined as a function of the peak detected frequency (A i ) and the detected amplitude (B i ); the detected density being determined as a function of the detected humidity and the peak detected frequency (A i ) or the detected amplitude (B i ).  
   
   
       22 ) A method as claimed in  claim 20 , wherein a first deviation (A Δ ) between the peak detected frequency (A i ) and a reference frequency (A R ) is determined; a second deviation (B Δ ) between the detected amplitude (B i ) and a reference amplitude (B R ) is determined; and the detected density of the tip ( 3 ) of the cigarette ( 4 ) is determined as a function of the first and second deviation (A Δ , B Δ ); the reference frequency (A R ) and the reference amplitude (B R ) being the peak frequency and mid-peak-height amplitude respectively of a reference curve (C R ) of a reference signal obtained with substantially no objects in the microwave field ( 14 ).  
   
   
       23 ) A method as claimed in  claim 22 , wherein the detected humidity of the tip ( 3 ) of the cigarette ( 4 ) is determined as a function of the first and second deviation (A Δ , B Δ ), and the detected density is determined as a function of the detected humidity and the first or second deviation (A Δ , B Δ ).  
   
   
       24 ) A method as claimed in  claim 23 , wherein the detected humidity of the tip ( 3 ) of the cigarette ( 4 ) is determined according to the following equation:  
     
       
         
           
             φ 
             = 
             
               arctg 
               ⁢ 
               
                   
               
               ⁢ 
               
                 
                   A 
                   Δ 
                 
                 
                   B 
                   Δ 
                 
               
             
           
         
       
     
     where φ is directly proportional to the detected humidity, A Δ  indicates the modulus of the first deviation, and B Δ  indicates the modulus of the second deviation.  
   
   
       25 ) A method as claimed in  claim 23 , wherein the detected density of the tip ( 3 ) of the cigarette ( 4 ) is determined using test curves (T), each of which is predetermined experimentally at a respective given constant humidity; and each curve (T) describes the density pattern as a function of the ratio A Δ /A i .  
   
   
       26 ) A method as claimed in  claim 20 , wherein the detected density is compared with the reference data item.  
   
   
       27 ) A method as claimed in  claim 26 , wherein an error signal is emitted when the difference between the detected density and the reference data item exceeds a threshold value.  
   
   
       28 ) A method as claimed in  claim 15 , wherein the detection signal is broken down into two components (A i , B i ), each of which is a function of the humidity and density of the tip ( 3 ) of the cigarette ( 4 ); the detected humidity is determined as a function of the two components (A i , B i ); and the detected density is determined as a function of the detected humidity and at least one of the two components (A i , B i ).  
   
   
       29 ) A packing machine comprising a device ( 1 ) for controlling the fill of tips ( 3 ) of cigarettes ( 4 ), as claimed in  claim 1.