Note: Descriptions are shown in the official language in which they were submitted.
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Description
The inven-tion relates to a procedure and an apparatus
for identifying the combustion line of -the wrapper
encasing a smokable article (in particular the
combustion line of cigarette paper, wrapper leaf or
synthetic wrapper).
DE-OS 2 947 249 (German Patent Application) published
May 27, 1981 describes a method for determining the rate
of combustion and/or glow of a smokable article whereby
a sensor capable of detecting the radiation from the
incandescent zone of the smokable article is made to
travel parallel with the movemen-t of that zone, while
the exact position of the sensor along the path of travel
is plottéd in relation of time by means of an electrical
signal. By this means it is possible to determine the
location of the lncandescent zone throughout the period
during which the smokable article is being smoked - i.e.
during puffs and during the intervals between puffs -
thus enabling the rate of combustion and/or glow to be
ascertained.
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Apart from the rate of combustion and/or glow,-a
further important parameter for a smokable article
such as a cigarette is the behaviour of the wrapper
material - for example, cigarette paper, wrapper leaf
or synthetic wrapper - during thermal decomposition.
The thermal decomposition behavioux can be influenced
by the choice of appropriate materials, which in turn
have a corresponding influence on the actual line of
combustion, i.e. the point of transition between the
ash and the unburnt wrapper material. Among the factors
which can be influenced by the thermal decomposition
behaviour - and thus by the speed of advance of th~
combustion line - are the puff resistance of the
conical incandescent zone, the degree of ventilation
of the buxning smokable article, the rate of combustion
and the smoke yield.
The recognized method for determining the rate of
combustion and/or glow of the incandescent zone is not
suitable for plotting the advance of the combustion
line due to the fact that the combustion line precedes
the area of maximum incandescent-zone temperature by
a certain distance, i.e. there i5 no direct correlation
between the rate of combustion and/or glow on the one
hand and the advance of the combustion line on the other~
In practice, therefore, it has hitherto not been possible
to monitor the advance of the combustion line except
by purely visual means.
The preserlt inv~nt:;(.)~î w.~ tnc.~e:to:r.e clevi.secl ~J:ith the
aim oE creatin~ an apparatus Eor iclentifying the com-
bus-tion line o~ a srnokable ar-ticle (in particular the
eomb~stion line of cigare-t-te paper, wrapper leaf or
synthetic wrapper) in such a way tha-t the movement
of the combustion line can be plotted or reeorded
by fully automatie means.
In particular the invention is designed to determine and
reeord the combustion line throughout the entire smoking
proeess, i.e. not only in the intervals between puffs
but during the puff phases as well.
Aceerdingly, the present invention is an apparatus for
opto-eleetronie identifieation of the eombustion line
of the wrapper eneasing a smokable artiele (in partic-
ular the eombustion line of eigarette paper, wrapper
leaf or syn-thetie wrapper) whieh incorporates two
source and sensor assembly units (hereinafter SSA units)
positioned side by side for moving in the direetion of
travel of -the eombustion line for refleetive sensing
~0 applications, a subtracter for the output signals from
the sensors of the two SSA units, and a device for detect-
ing a sudden differenee in the output signals from the
SSA units at the point of transition from ash to wrapper
at the combustion line.
The benefits of this invention derive from the exploita-
tion of the fact tha-t the wrapper material (e.g. eicJarette
paper), the eombustion line and the ash produced by the
burnin~ tobaeeo in the ineandescent zone all possess
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different refl.ective characteristics. These character-
istics are determined and recorded by source ancl sensor
assembli.es for reflective sensiny applications (herein-
after referred to as SSA or SSA units).
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An electronic analyzin~ device records the glow
rate of the combustion lins during the inkervals
between puffs, as well as the speed of advance of
the combustion line during the puff phases.
By using this apparatus it is therefore possible to
carry out investigations into the influence of
various wrapper materials - e~g. cigarette papers
to which certain substances have been added - on
the thermal decomposition behaviour of the wrapper,
as well as investigations into other important
parameters for smokable articles.
The degree of reflectance of the surface of the
smokable article ~ i.e. of its wrapper material
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~5 determined b~ means of a commercially available
SSA unit which utilizes a light emitting diode
(LED) operating at infrared frequencies as a
transmitter and a suitable phototransistor as a
receiver. The measured signal caused by a change
in the degree of reflectance of the surface of the
smokable article is subject to two disturbance
variables, namely a variation in the distance between
the surface of the smokable article and the SSA unit~
and the infrared emission from the incandescent zone
of the smokable article.
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The effect of any varlations in distance between
the SSA unit and the smokable article is
almost entirely offse-t by utiliziny two SSA units
mounted side by side and by computing the difference
in the signals received by the two units~
The infrared emission from the incandescent zone of
the smokable article in1uences the opto~electronic
xeceiver of the SSA unit. However, as ~he infrared
emission from the incandescént zone is continuous, it
is possible to compensate for any error by con-trolling
the LEDs of the SSA unit with a sinusoidal AC voltage
supply wich is shifted upwards by a constant DC
voltage~
If the alternating components~of the received signals
are then isolated and rectified after determination
-of the diference in signal, the result is a voltage
which is proportional to the di~ference in the degree
of reflectance at the points scanned by the two SSA
units.
Fluctuations in the perormance of the two SSA units
result in a phase shift between the two received signals.
This phase shift can be offset by means of a phase
shifter incorporated in the transmitter circllit of one
of the SSA units. If thls phase shift is not offset,
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the difference between the two signals - even if
the degree of reflectance at the two points scanned
is the same - is sufficient to generate a relatively
high output voltage, which in turn results in instrument
error~
As the smokable article is normally attached rigidly
to the smoking machine, and cannot therefore be moved,
m~>y 1~
the SSA units a~e mounted in such a way that they can
travel forward in accordance with the movemen~ of the
combustion line~ The SSA units are therefore moved
via a rack and pinion gear which is driven by an
electric motor.
This motor is controlled in such a way that it moves
the two SSA units bacK and forth over a range within
which the analyzed output signal fromthe two units
does not fall below a c~rtain minimum limit. In one
preferred design this minimum limit lies above the
zero-signal level of the two SSA units.
This constant back-and-forth movement of the motor -
and hence of the two SSA units - in ~he vicinity of
the combustion line produces a sufficiently larye
number of readings for accurate analysis and evaluation.
During the puff phase the infrared emissisn from the
incandescent zone of the smokable article is so
powerful that the phototransistor of the SSA unit
closest to the incandescent zone exceeds saturation
point and therefore ceases to deliver any signal. By
means of a time switch the motor is therefore triggered
by the smoking machine in such a way that the two SSA
units are moved slightly faster during the puff phase
than the actual speed of the combustion line.
Immediately after the puff the infrared emission from
the incandescent zone falls to a level where the
combustion line can once again be identified by the
SSA unit directly in line with it.
The position of the motor which moves the two SSA units
thus serves to indicate the position of the two SSA
unitsO A potentiometer coupled to the motor and
connected to a refexence voltage supply thus delivers
an output voltage which is in proportion to the
position of the SSA units~ This output voltage is then
registered by means of an x-t recorder, thus providing
a direct indication of the rate of progress of the
combustion line.
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The incorporation of further switching devices makes
it possible to plot the position/time curve of the
SS~ units, and thus ko plot the forward movement of
the combustion line at a series of points~
The invention is describ0d in more detail below with
reference to a prototype model as specified in the
attached graphs and diagrams. These gra~hs and diaarams
are as follows:
Fig. 1 General view of the apparatus for identifying
the combustion line of a cigarette
Fig. 2 Block writing diagram of the electronic circuitry
for the apparatus as shown in Fig. 1
Fig. 3 Perspective view of the two SSA units
Fig~ 4 Graphs showing the output signals from the two
SSA units without phase shift
Fig. 5 The non-rectified diffe.rence signal from the two
and 6 SSA units where the degree of reflectance is the
same at the two points scanned
Fig~ 7 The difference signal at the poin~ where the
combustion llne is identified
Fig. 8 Time curve for the voltage U as the combustion
line passes in front oE the stationary SSA units
Fig. 9 ~raph representing the fluctuations .in the
voltage Um and the limiting values (-to be
explained subsequently)
Fig. 10 Graph representing the movement of the combustion
line of a cigarette during smoking
Figure 1 shows the general design of an apparatus for
identifying the combustion line of a cigarette. The
cigarette consists of an incandescent zone ~13, the
paper combustion line which is to be monitored ~2),
the cigarette strand ~3) and a filter (4), which is
clamped into a standard holder (5). The holder (53 is
inserted into a smoking machine (6~, which can be
programmed to "smoke" the cigarette according to a
pattern that simulates the behaviour of a human smokerO
Parallel to the cigarette is a toothed rack (93, on
which is mounted a sliding head carrying two SSA units
(RL 1, RL 2) positioned side by side. The rack ~33 can
be rotated by means of an electric motox (113, thus
causing the two SSA units (RL 1, RL 2) to move parallel
with the ciyarette. A displacement transducer (10~
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is connected either to the motor (11) or to the
rack (9). The output signal of the displacement
transducer (10) is proportional to the rotation of
the rack (9~/electric motor (11~ and thus to the
position of the SSA units ~RL 1, RL 2).
The output signals from the two SSA units, i.e.
the received signals, are fed in-to an analyzing
device 112), which controls the motor via a control
unit ~13~ and receives the signal from the displacement
transducer (10). The analyzing device (12) is connected
to a recording device (14~ n
Figure 3 shows a perspective view of the two SSA units
~RL 1, RL 2), each of whi.ch contains a light-emitting
diode operating at infrared frequencies as a t.ransmitter,
and a suitable phototransistor (F~) which receives the
light reflected from the surface of the cigarette. In
order to ensure that ~he points scanned by the two
SSA units (RI. 1, RL 2) are as close together as
possible, an adjusting wedge (35) is posi-tioned between
the two units (R~ 1, RL 2) in such a way that it
maintains the units (RL 1, RL 2) at a predetermined
angle to each other. This angle is 13 in the cas~ of
the apparatus described.
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The two SSA units (RL 1 and ~L 2) are mounted toyether
on the toothed rack ~9) by means of an attachment
and can be made to move parallel with the ciyarette.
If only one SSA unit were to be used, any varia~ion
in the distance between this single unit and the
cigare-tte would result in a corxesponding change in
the received signal. In order to minimize this effect,
the apparatus described utilizes two SSA units (RL 1,
~L 2) so that any variations in distance can be
almost completely offset by computing the difference
between the two signals (E1 and E2) received by the
two units.
As can be seen from Figure 2, the two SSA units (RL 1
RL 2~ are ed from a constank voltage source 515)
which supplies a DC voltage (U1) and from a generator
~163 which supplies a ~inusoidal AC voltage. Th~
sinusoidal AC voltage from the generator (16~ and the
DC voltage tU1) are fed into the first subtracter 517
so that the LEDs (transmitters) of the kwo SSA units
(RL 1f RL 2) are driven by a sinusoidal AC voltage
which is shifted upwards by the DC voltage U1.
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The output of the subtrac~er t17) is linked to a
junction (18), which is connected directly to the
first SSA unit (RL 1) and via an all-pass network
519) to the second SSA unit (RL 2~. This all-pass
network compensates for -the phase shifts between the
two received signals caused by fluc~uations in the
performance of the two units. Figure 4 shows the
phase shift between the two received signals which
occurs when the transmitters of the two SSA units
(RL 1I RL 2) are powered directly by the supply voltage,
The difference between these two signals - even if
the degree of reflec-tance at the two points scanned is
the same ~ would be sufficient to genera~e a relatively
high output voltage r thus resulting in a faulty reading.
For this reason the phase shift must be offset by
means of the all-pass network (19).
The light emitted from the LEDs (transmitters) is
reflected from the surface of the cigarette and
picked up by the phototransistors, which generate an
output signal in proportion to the degree of
reflectance at the surface of the cigarette. The output
signals from the phototransistors are then fed into
two high-pass filters ~20 and 21), thus isolating
the alternating components of the received signals
E1 and E2. These signals are then converted.
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By feeding the two transmitters wi~h the sinusoidal
AC voltage which is shifted upwards by the DC supply
voltage U1~ it is possible to distinguish between the
reflected infraxed light and the infrared emission
from the incandescent zone, which con-tinuously
irradiates the two receiversO
The outpu~ signals from the two high-pass filters ~20
and 21) - i.e. the alternating components of the
signals received by the two 5SA units ~RL 1 and ~L 2) -
are fed into a second subtracter (22~, which produces
the difference between the two output signals. This
difference is then amplified by means of an amplifier
(23) and fed into a rectifier (24), the output signal
from which represents the actual voltage IUm3, i.e. a
voltage which is in proportion to the difference in
the degree of reflectance ( ~3 at the points scanned
by the two SSA units ~RL 1, RL 2)o
Figures 5 and 6 show the two received signals E1 and
E2, i.e~ ~he output signals from the two SS~ units
(RL 1 and RL 2). In Figure 5 the two signals are shown
in phase, while in Figure 6 they are in phase oppostion.
Figures S and 6 also show the non-rectified difference
signal, i.e. the difference between the two received
singals E1 and E2 when the degree of reflectance (~
is the same at the two points scanned.
Figure 7 shows the non-rectifled difference signal
for the two received signals (E1 and E2) in phase
opposition when the combustion line is identifiedO
This signal is the result of the difference in the
degree of reflectance of the ash and that of the
unburnt paperO
The difference signals sho~n in Figures 5 to 7 are
thus generated at the output of the second subtracter
(22).
After rectification in the rectifier (24), the voltage
Um can be registered by a meter. Figure 8 shows the
curve for the voltage Um as the paper combustion
line passes in front of the two stationary SSA units
(RL 1 and ~L 2). The graph shows an obvi~us peak which
marks the transition between the two reflecting zones,
i.e. the ash and the surface of the paper. As explained
above, this sudden transition is due to the different
degrees of reflectance (3 3 at the two points scanned.
If the two points scanned by the two SSA units (RL 1
and RL 2] are both located on the ash or the paper
surface~ the difference signal will fall to zero, or
approximately zero, as is shown in Figures 5 and 6
together with Figure 8. Figure 8 also shows a number
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of levels (1L, 2L, 1H, 2H) on either side o~ the
peak value for UmO These levels are selected at
random on the sole condition that they lie above the
apparatus noise threshold.
The output signal from the rectifier (24), i~eO the
voltage Um, is applied via two junctions ~25 and 27
to two Schmitt triggers (26 and 28). One of these
Schmitt triggers (26) is linked via a junction (29)
to a third subtracter (31). With the aid of a voltage
source U2 (32) the speed of forward and reverse movement
can be varied. The output signal from the subtracter
(31) is applied via an amplifier (33) to the motor
111). The Schmitt trigger (26) :is controlled when the
rectified difference between the signals E1 and E2
received by the two 5S~ units (RL 1 and RL 2l - iOe.
the voltage Um - is less than 2L and greater than 2H
(see figures 8 and 9), thus causing the motor (11) to
move the two SSA units (RL 1 and RL 2) back and forth
in such a way that the voltage (Um) always remains within
the range defined ~y these two extreme values. Figure
9 shows the corresponding switch-over points t2L and t2H~
which are dependent on the output voltage Ux2 from the
Schmitt trigger ~26~.
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The constant rotation and counter-ro~a~ion of th~
motor (11) ~ which effects a corresponding back-and-
forth movement of the two SSA units (RL 1 and RL 2~ -
provides a sufficientl.y large number of readings for
accurate evaluation and analysis.
During the puff phase, i.e. while the smoking machine
(6) is in operation, the infrared emission from the
incandescent zone (1~ is so powerful that the
phototransistor (FT) of the SSA unit closest to that
zone exceeds saturation point and therefore ceases
to deliver a measurable signal.
By means of a time switch (not shown) the motor ( 11 )
is then triggered by the smoking machine in such a
way that it causes the two SSA units (RL 1 and RL 2)
to move slightly faster during the puff phase than
the actual speed of advance of the combustion line.
In Figure 2 this adaptation is indicated by a
transducer l34~, which is linked both to the third
subtracter (31) and to the smoking machine (6) 7 This
transducer (34) serves to trigger the mo-tor (11) via
the smoking machine (6) during the puff phases~
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Immediately following the end of a puff phase
the infrared emission from the incandescent zone
falls to a level where the combustion line (2) -
with which the SSA units are still aligned -
can once again be detected.
The two SSA units are displaced via the too-thed
rack (9j (indicated in the diagram by a dotted line)
by the motor (11), which is controlled accordingly
by the voltage Um and the Schmitt trigger (26).
Either the rotation of the motor (11) or the position
of the rack ~9) therefore serves to indicate the
position of the two SSA units (RL 1, RL 2). For this
purpose a displacement transducer (10) - e.gO a
potentiometer connected to a reference vol-tage supply -
is coupled to the motor (11) or to the rack (9).
This potentiometer delivers an output voltage which
is in proportion to the position of the two SSA units
iRL 1 and RL 2)o The output voltage is registered by
a recording device (14) (e.g. an x-t recorder3, thus
providing a direct indication of the rate of advance
of the paper combustion lineO
As explained above, the Schmitt trigger 126) switches
between the two values 2L and 2H (see Figure 8)o The
second Schmitt trigger (28), which receives the
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voltage Um via the junction (27~, swi.tches between
the values 1L and 1H 5see Figure 8), so that the two
Schmitt triggers (26 and 28~ generate the corresponding
output voltages U 1 and U 2~ These two output voltages
Uxl and Ux2 are then fed into a logic unit (30), either
directly via the second Schmitt trigger (28), or
indirectly via the first Schmitt trigger (26) and the
junction (291, The logic unit (30) combines the two
output signals x1 and x2 in accordance with the following
logical function:
Y ~ X2
The output signal y from the logic unit (30~ is then fed
to the pen lift connection o the x-t recorder (14).
The logic combination of the two output signals as
described makes it possible to present the curve as a
series of separate points due to the fact that the pen
of the x~t recorder (14~ only traces the curve when
the two SSA units (RL 1 and RL 2) are located between
the two limiting values 1L and 2L and are moving
towards 2Lo
The corresponding switch-over points t1L and t1~ which
are dependent on the output voltage Ux1 from the second
Schmitt trigger, are indicated .in F:igure 9.
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Finally, Fig. 10 shows the movement of the combustion
line of a cigarette, as recorded by the two SSA units
(RL 1 and RL 2) moving parallel with the incandescent
zone. The breaks in the curve caused by the lifting
of the pen can be clearly seen.
