Method and apparatus for regulating the permeability of cigarette wrappers and the like

A laser or a spark discharge apparatus which is used to perforate the wrapping material for rod-like fillers of tobacco and/or filter material is adjusted in dependency on variations of the characteristics of signals which denote the mass per unit length of a trimmed filler having a predetermined hardness. The wrapping material is tipping paper or cigarette paper and can be perforated prior or subsequent to draping around the trimmed filler, and the draped filler is thereupon subdivided into sections of desired length. Signals denoting the mass per unit length of the filler can be influenced by signals denoting the hardness of the filler, the filling power of the filler, the temperature of fibrous material of the filler, the moisture content of fibrous material of the filler and/or other parameters of the fibrous material and/or filler.

BACKGROUND OF THE INVENTION 
The invention relates to methods and apparatus for regulating the 
permeability of wrappers of plain or filter cigarettes, cigars, 
cigarillos, filter rod sections and like rod-shaped articles of the 
tobacco processing industry. More particularly, the invention relates to 
improvements in methods of and apparatus for regulating the permeability 
of wrappers of rod-shaped articles of the tobacco processing industry 
(hereinafter called cigarettes for short) whose fillers are formed from 
fibrous material the filling power of which is monitored in order to 
maintain the hardness of the fillers at a constant value. The fibrous 
material can constitute natural, reconstituted or artificial tobacco 
(which may but need not contain nicotine) and/or filter material. 
In the manufacture of cigarettes, fibrous material (hereinafter called 
tobacco for the sake of convenience and simplicity) is continuously 
gathered into a thin layer which is converted into a narrow stream. The 
stream is equalized to be converted into a rod-like filler which is 
thereupon condensed and is simultaneously draped into cigarette paper or 
other suitable wrapping material in a wrapping mechanism to form a rod 
which is severed at desired intervals to yield a succession of cigarettes 
of unit length or multiple unit length. The equalizing operation normally 
involves removing from the stream the surplus of fibrous material in 
accordance with the measurement of the mass flow (quantity or mass per 
unit length of the filler) by a monitoring device which can include a 
source of corpuscular radiation (e.g., beta rays) and an ionization 
chamber. A cigarette making machine which operates in the just described 
manner is manufactured by the assignee of the present application and is 
known as PROTOS. The distributor unit of the PROTOS machine is described 
in the commonly owned U.S. Pat. No. 4,185,644 to Heitmann, and the rod 
forming and subdividing unit is described, for example, in commonly owned 
U.S. Pat. No. 4,280,516 to Reuland. 
If the cigarettes are to be assembled with filter mouthpieces to form 
filter cigarettes, plain cigarettes issuing from the cigarette maker are 
fed into a tipping machine wherein they are united with filter mouthpieces 
by means of adhesive-coated uniting bands consisting of so-called tipping 
paper. The filter cigarettes are tested for the quality of their fillers, 
wrappers, mouthpieces and/or junctions between the tobacco-containing 
portions and filter mouthpieces, and the wrapper of each filter cigarette 
can be provided with perforations for admission of atmospheric air into 
the column of tobacco smoke. A filter tipping machine which can be used 
with the PROTOS cigarette maker is manufactured by the assignee of the 
present application under the name MAX 80. Reference may be had to 
commonly owned U.S. Pat. No. 4,281,670 to Heitmann. Commonly owned U.S. 
Pat. No. 4,177,670 to Heitmann discloses a method of monitoring the 
permeability of the wrappers of filter cigarettes, and the U.S. Pat. No. 
4,281,670 further discloses the manner in which one or more lasers can be 
used to perforate the wrapping material. Commonly owned U.S. Pat. No. 
4,247,754 to Baier discloses an apparatus for perforating wrapping 
material for cigarettes or the like by discharging sparks between opposite 
sides of the wrapping material. 
It is further known to regulate the formation of a tobacco filler in such a 
way that the hardness (filling power) of successive increments of the 
filler matches or closely approximates a preselected value. Hardness is 
important to the smoker because her or his fingers can readily ascertain 
the resistance which the filler of a cigarette offers to depression. Such 
hardness can be monitored and regulated in lieu of monitoring and 
regulating the mass or quantity of fibrous material per unit length of the 
filler. The reason that certain manufacturers of cigarettes prefer to 
monitor and regulate the hardness is that the smoker is much more likely 
to be positively influenced by the satisfactory hardness than by the 
satisfactory mass or quantity per unit length of a filler which is 
subdivided into the fillers of cigarettes because the hardness of a 
cigarette is readily detectable but not the exact weight. Hardness of 
cigarettes can be ascertained with a suitable densimeter, e.g., with a 
so-called Borgwaldt densimeter. Satisfactory or standard hardness is 
denoted by a certain level of the movable part of the Borgwaldt 
densimeter. 
Density of cigarette fillers or cigarette rod fillers can be ascertained 
directly or indirectly. Direct monitoring of the density with flowing air 
is disclosed in commonly owned U.S. Pat. No. 3,921,644 to von der Lohe and 
in British Pat. No. 1,422,992. German Offenlengungsschrift No. 22 41 774 
discloses a different mode of monitoring the hardness of the filler, 
namely by ascertaining the force which the compacted tobacco stream 
applies to the wrapping mechanism during the application of a web of 
cigarette paper or the like. Indirect determination of filling power of a 
tobacco filler is disclosed in the aforementioned U.S. Pat. No. 4,280,516 
to Reuland. Signals denoting the filling power can be converted into 
signals denoting the hardness of the filler. Reuland proposes to relate 
signals denoting the mass flow to signals which denote the height of the 
equalized stream. Another indirect determination of the hardness of a 
filler is disclosed in commonly owned U.S. Pat. No. 4,290,436 to Reuland 
who proposes to relate signals denoting the height of the equalized stream 
to signals which denote the height of the unequalized stream. Commonly 
owned U.S. Pat. No. 4,284,087 to Reuland discloses a different indirect 
determination of hardness according to which signals denoting the 
resistance which the equalized tobacco stream offers to penetration of air 
are processed with signals denoting the height of the equalized stream. 
Commonly owned U.S. Pat. No. 4,249,545 to Gretz discloses an apparatus for 
perforating the wrappers of cigarettes in dependency on a characteristic 
of the wrapper or filler of a cigarette. However, this reference does not 
disclose or propose to make the perforating operation dependent upon the 
mass per unit length of a filler whose hardness is constant. 
OBJECTS AND SUMMARY OF THE INVENTION 
An object of the invention is to provide a novel and improved method of 
regulating the permeability of wrappers of rod-shaped articles of the 
tobacco processing industry in such a way that the regulating operation 
does not affect the taste, aroma and/or other desirable characteristics of 
tobacco smoke. 
Another object of the invention is to provide a method which allows for a 
predictable regulation of the permeability of wrapping material for use in 
the making of cigarettes or the like while the quantity of condensate is 
kept at a constant value so that such quantity can be reliably reported on 
the packs of cigarettes and like rod-shaped smokers' articles. 
A further object of the invention is to provide a novel and improved method 
of regulating the permeability of wrappers for rod-like fillers whose 
hardness is constant or at least closely approximates a selected value. 
An additional object of the invention is to provide a novel and improved 
apparatus for the practice of the above outlined method. 
Still another object of the invention is to provide a cigarette maker which 
embodies the improved apparatus. 
A further object of the invention is to provide a filter tipping machine 
which embodies a portion of or an entire apparatus of the present 
invention. 
An additional object of the invention is to provide an apparatus which can 
be installed in or combined with existing cigarette making, filter tipping 
and like machines. 
Another object of the invention is to provide an apparatus which can employ 
many components of conventional cigarette making, filter tipping and like 
machines. 
One feature of the invention resides in the provision of a method of 
regulating the permeability of wrappers of cigarettes or other rod-shaped 
articles of the tobacco processing industry. The method comprises the 
steps of forming a rod-like filler containing fibrous material (e.g., 
fragments of tobacco leaves) and having a predetermined hardness, draping 
the filler into wrapping material, generating first signals denoting the 
mass per unit length of the filler, perforating the wrapping material 
prior and/or subsequent to draping, and utilizing the first signals to 
adjust the perforating step. The signal generating step can include 
continuously and automatically monitoring the mass per unit length of a 
continuously moving filler. 
The method can further comprise the steps of generating second signals 
denoting the filler power of fibrous material and utilizing the second 
signals (e.g., in a trimming or equalizing device for the filler) to 
influence the mass per unit length of the filler. Alternatively, or in 
addition to the just described steps, the method can comprise the steps of 
generating signals denoting the hardness of the filler and using such 
signals to influence the mass per unit length of the filler. Signals 
denoting the hardness and/or filling power of fibrous material can be used 
to equalize the filler prior to the draping step. 
The method further comprises the step of subdividing the draped filler into 
rod-like sections of predetermined length and such method can further 
comprise the steps of tipping the sections of predetermined length by 
providing them with filter mouthpieces. The perforating step can comprise 
changing the permeability of the wrapping material of tipped sections. The 
wrapping material can include tipping paper which is used to unite 
sections of predetermined length with filter mouthpieces, and the 
perforating step can include changing the permeability of the tipping 
paper. The filter mouthpieces then preferably comprise foraminous outer 
layers. 
The perforating step can include subjecting the wrapping material to the 
action of one or more laser beams and/or effecting a spark discharge 
between opposite sides of the wrapping material. 
The method can further comprise the step of generating signals denoting the 
moisture content and/or the temperature of fibrous material and utilizing 
such signals to influence the first signals. Signals denoting the 
temperature and/or the moisture content of fibrous material can be used to 
influence the first signals in addition to or in lieu of signals which 
denote the hardness and/or filling power of the filler. 
The method preferably further comprises the step of monitoring the 
permeability of perforated wrappers, generating additional signals 
denoting the monitored permeability, comparing the additional signals with 
the first signals and generating third signals denoting the differences 
between the first and additional signals, and using the third signals to 
regulate the perforating step. 
Another feature of the invention resides in the provision of an apparatus 
for making cigarettes or analogous rod-shaped articles of the tobacco 
processing industry. The apparatus comprises means (such as a distributor 
unit, a rod treating unit and a filter tipping unit or two of these units) 
for forming a rod-like filler containing fibrous material (such as 
fragments of tobacco leaves) and having a predetermined hardness, means 
for draping the filler into wrapping material (such as tipping paper 
and/or cigarette paper), means (e.g., a function generator) for generating 
first signals denoting the mass per unit length of the filler, adjustable 
(e.g., laser-employing and/or spark generating) means for perforating the 
wrapping material, and means (e.g., a regulating device for the 
laser-operated perforating means) for adjusting the perforating means as a 
function of the first signals. 
The apparatus can further comprise means for equalizing the filler, means 
for generating second signals denoting the hardness of the equalized 
filler, and means (e.g., a signal comparing stage) for adjusting the 
equalizing means as a function of second signals. Such apparatus can 
further comprise means (e.g., an additional signal comparing stage or one 
of several function generators) for influencing the adjusting means for 
the perforating means as a function of the second signals. 
The apparatus can comprise adjustable means for regulating the mass per 
unit length of the filler (such adjustable regulating means can constitute 
or include the aforementioned equalizing means), means for generating 
second signals denoting the filling power of the fibrous material, and 
means (e.g., a pair of signal comparing stages or a signal comparing stage 
in conjunction with one of several function generators) for adjusting the 
regulating means as a function of the intensity and/or another 
characteristic of the second signals. For example, the means for adjusting 
the regulating means can comprise a first signal transmitting function 
generator, and the means for generating the first signals can comprise a 
second signal transmitting function generator which modifies the signals 
from the first function generator and transmits the modified signals to 
the means for adjusting the perforating means. The forming means can 
comprise a distributor which is arranged to form a continuous stream of 
fibrous material, and the means for generating second signals can be 
disposed in the distributor. The means for generating the second signals 
can include means for monitoring the filling power of the undraped filler. 
The means for forming the filler can comprise means for providing the 
filler with a surplus of fibrous material which is removed with the 
aforementioned equalizing means to thus influence the mass per unit length 
of the equalized filler. The equalizing means can be adjusted as a 
function of variations of density of the equalized filler. 
The apparatus preferably further comprise means for generating additional 
signals denoting the permeability of perforated wrappers, and the means 
for adjusting the perforating means then preferably comprises means for 
comparing the additional signals with the first signals and for generating 
third signals when the additional signals deviate from the first signals. 
The third signals are used to adjust the perforating means by way of the 
respective adjusting means. 
The apparatus can comprise a source of wrapping material in the form of 
tipping paper and/or a source of wrapping material in the form of 
cigarette paper or the like. 
The apparatus can further comprise means for influencing the first signals 
as a function of fluctuations of the moisture content and/or temperature 
of fibrous material and/or the hardness and/or the filling power of the 
filler. In addition to or in lieu of such influencing, the first signals 
can be influenced by signals denoting the blend of fibrous material which 
is used to form the filler. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The improved machine 
and apparatus themselves, however, both as to their construction and their 
mode of operation, together with additional features and advantages 
thereof, will be best understood upon perusal of the following detailed 
description of certain specific embodiments with reference to the 
accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a filter cigarette making machine which comprises a 
distributor unit VE (e.g., of the type disclosed in U.S. Pat. No. 
4,185,644 to Heitmann and used in the aforementioned PROTOS machine), a 
rod treating unit SE (e.g., of the type disclosed in U.S. Pat. No. 
4,280,516 to Reuland and used in the PROTOS machine), and a filter tipping 
unit FA (e.g., of the type disclosed in U.S. Pat. No. 4,281,670 to 
Heitmann and used in the PROTOS machine). 
The distributor unit VE comprises a so-called distributor V (also called 
hopper) which serves to form a thin layer of tobacco particles and to 
convert such thin layer into a narrow stream S. The unit VE further 
comprises a temperature monitoring or measuring device T which generates 
signals denoting the temperature of successive increments of the stream S. 
The device T can comprise a conventional semiconductor which is installed 
in a channel for the tobacco stream and is influenced by changes in the 
temperature of successive increments of the stream S which is conveyed in 
a direction to the left. The temperature measuring device T is followed by 
a moisture measuring or monitoring device F which generates signals 
denoting the moisture content of successive increments of the stream S. A 
suitable moisture measuring device is disclosed in commonly owned U.S. 
Pat. No. 3,979,581 to Reuland. The device F is followed by an adjustable 
stream trimming or equalizing device E which removes the surplus from and 
thus converts the stream S into a rod-like filler which enters the rod 
treating unit SE. A suitable trimming or equalizing device is used in the 
PROTOS machine. The device E converts the stream S into a rod-like filler 
which has a predetermined cross-sectional outline as a result of removal 
of the surplus of tobacco extending from one or more sides of the stream 
to thus smoothen the external surface of the trimmed stream. An electric 
motor or other suitable means can be used to move the trimming device E 
relative to the stream S so as to change the plane of removal of the 
surplus and hence the quantity of fibrous material per unit length of the 
filler. Reference may be had to numerous U.S. patents of the assignee of 
the present application. Thus, the device E can influence the mass flow of 
fibrous material into the rod treating unit SE. 
The rod treating unit SE comprises a conventional wrapping device Fo which 
drapes the filler into a continuous web of wrapping material (such as a 
strip of cigarette paper which is drawn from a reel or another suitable 
source). The wrapping device Fo is followed by a conventional paster B 
which applies a film of adhesive to one longitudinally extending marginal 
portion of the running web of wrapping material before such marginal 
portion is folded over the other marginal portion to complete the 
conversion of the web into a tubular body surrounding the equalized filler 
and to form with the other marginal portion of the web a seam extending in 
parallelism with the axis of the thus obtained cigarette rod. The seam is 
thereupon heated or cooled by a sealer N (e.g., a conventional tandem 
sealer) to promote rapid setting of the adhesive. 
The cigarette rod is monitored by a hardness measuring device H, e.g., a 
device of the type disclosed in U.S. Pat. No. 3,921,644 to von der Lohe, 
in British Pat. No. 1,422,992 or in German Offenlegungsschrift No. 22 41 
774. The device H generates signals denoting the hardness of successive 
increments of the filler in the cigarette rod. 
The device H is followed by a measuring or monitoring device D which 
generates signals denoting the mass flow (quantity or mass per unit 
length) of the filler in the cigarette rod. A suitable mass flow or 
density measuring device is manufactured by the assignee of the present 
application and is known as NSR. This device employs a source of 
corpuscular radiation (e.g., a source of beta rays) and an ionization 
chamber which serves as a transducer and transmits signals denoting the 
mass per unit length of the filler in the cigarette rod. 
The device D is followed by a cutoff M which subdivides the cigarette rod 
into a file of discrete plain cigarettes Z of unit length or multiple 
(e.g., double) unit length, and such cigarettes are caused to move 
sideways by a transfer device A of the type used in the aforediscussed 
PROTOS cigarette maker. The thus diverted cigarettes Z enter the filter 
tipping unit FA. 
The unit FA comprises an applicator AM (used in the aforediscussed MAX 80 
assembly of the PROTOS machine) which attaches to each cigarette Z one or 
more filter mouthpieces by using uniting bands made of so-called tipping 
paper which is drawn off a bobbin or from another suitable source and is 
draped around the abutting ends of filter mouthpieces and the respective 
cigarettes Z. Reference may be had to U.S. Pat. No. 4,281,670 to Heitmann. 
The thus obtained filter cigarettes FZ are introduced into an adjustable 
perforating apparatus Pe wherein their wrappers are provided with 
perforations to alter their permeability and hence the rate of admission 
of atmospheric air into tobacco smoke. As a rule, the apparatus Pe applies 
one or more annuli of perforations in the region where the filter 
mouthpiece of the filter cigarette FZ abuts the respective 
tobacco-containing portion (either a cigarette Z or a portion of a 
cigarette Z). The perforating apparatus Pe can employ one or more lasers 
as disclosed in U.S. Pat. No. 4,281,670 to Heitmann or a spark generating 
device of the type disclosed in U.S. Pat. No. 4,247,754 to Baier. If the 
device of Baier is used, the outer layers of the filter mouthpieces are 
preferably permeable to air. 
The reference character SL denotes an apparatus which is used to adjust or 
regulate the operation of the perforating apparatus Pe in accordance with 
a feature of the present invention. 
Filter cigarettes FZ1 which issue from the perforating apparatus Pe are 
introduced into a permeability measuring or monitoring device P which 
generates and transmits signals denoting the actual permeability of the 
wrappers of rod-shaped articles FZ1. A suitable monitoring device is 
disclosed in U.S. Pat. No. 4,177,670 to Heitmann. Tested filter cigarettes 
FZ2 are transported to storage, to a further processing station or to a 
packing machine. Defective filter cigarettes FZ2 are segregated from 
satisfactory filter cigarettes and are delivered to a device (not shown) 
which recovers the particles of tobacco and returns them to the magazine 
of the distributor V. 
The machine of FIG. 1 further comprises a signal comparing stage VG1 whose 
input a receives a reference signal denoting the desired permeability of 
the wrappers of articles FZ1, whose input b receives signals from the 
output of the measuring device P, and whose output c transmits difference 
signals to the adjusting apparatus SL to regulate the making of 
perforations in dependency on a plurality of parameters including the mass 
per unit length of the filler of the cigarette rod. 
A second signal comparing stage VG2 has an input a which receives a 
reference signal denoting the desired mass flow (mass per unit length of 
the filler), a second input b receiving from the device D signals which 
denote the actual mass flow of the filler, and an output c which transmits 
signals to the aforementioned electric motor or other suitable means for 
adjusting the device E and for thus changing the mass flow. 
A third signal comparing stage VG3 has an input a receiving a reference 
signal denoting the desired hardness of the filler, an input b receiving 
signals from the device H and denoting the actual hardness of the filler, 
and an output c which transmits difference signals to the input a of a 
function generator FG. The signal at the output c of the stage VG3 is 
further transmitted to the input a of the stage VG2. The signals PG at the 
output of the function generator FG are transmitted to the input a of the 
stage VG1 which, in turn, transmits signals to the adjusting apparatus SL. 
The signals PS are stored in the function generator FG and are modified in 
accordance with changes in characteristics of the input signals SG. It is 
assumed that the condensate K in the smoke which develops during smoking 
of tested filter cigarettes FZ2 is at least substantially constant i.e., 
that the taste of the smoke changes little or not at all. 
The input a1 of the function generator FG receives signals from the 
moisture measuring device F, and the input a2 of the function generator 
receives signals from the temperature measuring device T. Such signals 
influence the output signals PS. The input a3 of the function generator FG 
can receive signals from a device (not shown) which monitors the blend 
(mixture) of the material forming the stream S. 
Regulation of output signals PS in dependency on signals from the devices F 
and T is desirable and advantageous because the hardness of the filler 
depends on the temperature and moisture content of fibrous material 
forming the stream S. 
The mode of operation is as follows: 
The distributor V forms a homogeneous shower of tobacco particles, and such 
shower is converted into the narrow stream S. The devices T and F 
respectively generate signals which denote the temperature and the 
moisture content of successive increments of the stream S, and such 
signals are transmitted to the corresponding inputs a1 and a2 of the 
function generator FG. The stream S is equalized by the device E, and the 
resulting filler is draped into cigarette paper in the wrapping device Fo 
to form with the wrapping material a continuous cigarette rod. The 
wrapping material is coated with adhesive by the paster B, and the seam is 
conditioned by the sealer N upstream of the hardness measuring device H. 
The device H transmits to the input b of the signal comparing stage VG3 
signals which denote the hardness of successive increments of the filler 
in the cigarette rod, and successive increments of the filler in the rod 
are then monitored by the device D which transmits signals to the input b 
of the signal comparing stage SG2, such signals denoting the mass per unit 
length of the filler in the cigarette rod. The cutoff M subdivides the rod 
into discrete cigarettes Z which are deflected by the device A to enter 
the tipping device AM which turns out filter cigarettes FZ. The filter 
cigarettes FZ are treated in the perforating apparatus Pe which provides 
the wrappers of the plain cigarettes, the wrappers of the uniting bands 
and/or the wrappers of the filter mouthpieces with one or more rows or 
other arrays of perforations to thus increase the permeability of the 
wrappers. The operation of the apparatus Pe is regulated by the adjusting 
apparatus SL in accordance with the signals at the output c of the signal 
comparing stage SG1. Filter cigarettes FZ1 which leave the apparatus Pe 
are monitored in the device P which transmits signals denoting the 
permeabilities of the wrappers to the input b of the stage SG1. Such 
signals are compared with signals PS at the input a of the stage SG1, and 
the signals at the output c of the stage SG1 are indicative of differences 
between the characteristics of signals PS and signals from the device P to 
adjust the apparatus Pe accordingly by way of the apparatus SL. The device 
P ensures that the permeability of each filter cigarette FZ2 matches or 
sufficiently approximates that which is denoted by reference signals PS 
transmitted by the output of the function generator FG. 
If the device H transmits a signal whose intensity and/or another 
characteristic deviates from the corresponding characteristic of the 
selected reference signal at the input a of the stage VG3, the output c of 
the stage VG3 transmits a signal SG to the input a of the function 
generator FG. At the same time, the signal which is generated by the stage 
VG3 is transmitted to the input a of the stage VG2 whose output c then 
transmits a signal to adjust the level of the trimming device E, i.e., to 
change the mass flow of fibrous material in the path leading to the device 
D. The signals which are generated by the device D are compared with those 
at the input a of the stage VG2 to ensure that the adjustment of the level 
of the trimming device E is completed as soon as the mass flow reaches a 
value which is denoted by the characteristics of the signal at the input a 
of the stage VG2. 
The signal which is transmitted to the input a of the function generator FG 
influences the function generator to transmit a modified output signal PS 
which is transmitted to the adjusting apparatus SL by way of the stage VG1 
to influence the perforating action at Pe. The intensity and/or another 
characteristic of the output signal PS can also be influenced by signals 
which are applied to the inputs a1, a2, a3 of the function generator FG, 
i.e., by changes in the moisture content, temperature and/or mixture of 
fibrous material. Such signals influence the characteristics of the input 
signal SG. 
FIG. 2 shows a modified filter cigarette making machine wherein all such 
units, stages, devices and apparatus which are identical with or clearly 
analogous to the corresponding components of the machine of FIG. 1 are 
denoted by similar reference characters. 
The device H of FIG. 1 (which directly ascertains the hardness of the 
filler of the cigarette rod) is replaced with a device FK which is 
designed to indirectly monitor the hardness of the filler (e.g., in a 
manner as disclosed in U.S. Pat. No. 4,280,516, in U.S. Pat. No. 4,290,436 
or in U.S. Pat. No. 4,284,087) and to transmit appropriate signals to the 
input a1 of a first function generator FG1 which replaces the signal 
comparing stage VG3 of FIG. 1. The function generator FG1 transmits output 
signals SG which are applied to the input a of the signal comparing stage 
SG2 as well as to the input a1 of a second function generator FG2. Signals 
SG at the output of the function generator FG1 denote the desired mass 
flow of fibrous material. The operation of the function generator FG1 is 
based on the assumption that the hardness H of the filler is at least 
substantially constant. The inputs a2 and a3 of the function generator FG1 
receive signals from the moisture measuring device F and from the 
temperature monitoring device T, respectively. The input a4 of the 
function generator FG1 receives a signal denoting the mixture or blend of 
fibrous material forming the stream S. 
The signal SG at the output of the function generator FG1 is compared with 
the signal at the input b of the stage VG2, and the latter transmits a 
signal which is used to adjust the level of the equalizing device E until 
the signal from the mass flow measuring device D matches the signal from 
the output of the function generator FG1. The signals PS at the output of 
the second function generator FG2 are transmitted to the input a of the 
stage VG1 whose mode of operation is analogous to that of the similarly 
referenced stage in the machine of FIG. 1. The operation of the second 
function generator FG2 is based on the assumption that the quantity of 
condensate K in the smoke is substantially constant. The input a2 of the 
function generator FG2 receives a signal which is indicative of a 
characteristic of fibrous material, e.g., of the mixture of tobacco 
particles which form the stream. 
FIG. 3 shows certain detail of a distributor or hopper which can be used in 
the machine of FIG. 2 and contains a filling power or firmness measuring 
device FK2 which can be used in lieu of the device FK. Two carded drums 1 
and 2 are provided to draw tobacco particles from a magazine 3, and two 
picker rollers (not referenced) are used to expel fibrous material from 
the carding of the drums 1, 2 and to propel the expelled particles onto 
the upper reach of the endless belt 4 of a belt weigher or scale 6. A 
transducer 8 generates signals which denote the quantity of fibrous 
material on the upper reach of the belt 4 of the weigher 6, and such 
signals are transmitted to a regulator 9 for a motor 11 which drives the 
belt 4 at a variable speed. A feeder 7 supplies the removed surplus from 
the equalizing device E. The arrangement is such that the right-hand end 
of the belt 4 delivers fibrous material at a constant rate into an upright 
duct 12 wherein the upper level of the accumulated column of fibrous 
material is monitored by one or more photoelectric cells 13 or other 
suitable monitoring means in a manner which is described in U.S. Pat. No. 
4,185,644 to Heitmann. Signals which are generated by the monitoring means 
13 are transmitted to an evaluating circuit 14 which controls the 
operation of a variable-speed motor 16 for a carded drum 17 serving to 
draw fibrous material from the outlet at the lower end of the duct 12. 
Fibrous material which is entrained by the carding of the drum 17 is 
expelled by a picker roller 18 which propels the material onto a belt 
conveyor 19 corresponding to the conveyor 41 in FIG. 1 of U.S. Pat. No. 
4,185,644 to Heitmann. Heavier particles of fibrous material (such as 
fragments of tobacco ribs) are intercepted by a trough 21, and the lighter 
particles advance into the stream forming zone to be used for the 
formation of the stream S. 
If the filling power of fibrous material in the duct 12 remains unchanged, 
the drum 17 withdraws fibrous material at the rate at which the upper end 
of the duct 12 receives fibrous material from the belt 4 of the weigher 6. 
When the filling power of fibrous material changes, the drum 17 withdraws 
more fibrous material per unit of time than before (while its RPM remains 
unchanged) if the filling power of fibrous material decreases, and the 
drum 17 withdraws less fibrous material per unit of time (while its RPM 
remains unchanged) if the filling power of the fibrous material increases. 
The level of the column of fibrous material in the duct 12 then changes, 
and such change is detected by the monitoring means 13 which induces the 
evaluating circuit 14 to alter the RPM of the drum 17 so that the rate of 
withdrawal is again constant and the drum 17 again draws a stream wherein 
the mass flow is constant. Thus, the signal at the output of the 
evaluating circuit 14 is indicative of the filling power of fibrous 
material in the distributor V and can be transmitted to the input a1 of 
the first function generator FG1 of FIG. 2 in lieu of the signal from the 
filling power measuring device FK. It is further possible to connect the 
output of the evaluating circuit 14 with the regulator 9 for the motor 11 
so that the speed of the belt 4 of the weigher 6 can be caused to conform 
to the changed filling power of fibrous material. 
The perforating apparatus Pe can be designed to provide certain first 
portions of the wrappers with holes by means of one or more lasers and 
certain second portions of the wrappers with holes which are formed with 
spark discharge as disclosed in the patent to Baier. 
The signals which are applied to the input a3 of the function generator FG 
of FIG. 1 or to the input a4 of the function generator FG1 of FIG. 2 can 
be determined empirically. 
An important advantage of the improved apparatus and of the machine which 
embodies such apparatus is that the regulation of permeability of the 
wrappers does not affect the taste of the smoke and/or the quantity of 
condensate in the smokers' products so that it is possible to accurately 
report the quantities of condensate on the packs for cigarettes and the 
like. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic and specific aspects of my contribution to 
the art and, therefore, such adaptations should and are intended to be 
comprehended within the meaning and range of equivalence of the appended 
claims.