U.S. patent application number 11/248616 was filed with the patent office on 2006-04-20 for method and apparatus for measuring the diameter of a rod-shaped article.
This patent application is currently assigned to Hauni Maschinenbau AG. Invention is credited to Dierk Schroder.
Application Number | 20060081266 11/248616 |
Document ID | / |
Family ID | 35746552 |
Filed Date | 2006-04-20 |
United States Patent
Application |
20060081266 |
Kind Code |
A1 |
Schroder; Dierk |
April 20, 2006 |
Method and apparatus for measuring the diameter of a rod-shaped
article
Abstract
An apparatus and a method for measuring the diameter of at least
one rod-shaped article. A beam splitter is arranged to split a beam
coming from the radiation source into several component beams and
to conduct the beams from different directions onto the rod-shaped
article. A detection device includes a plurality of detectors each
arranged to generate a signal indicating a shading of a respective
one of the component beams caused by the rod-shaped article. The
rod-shaped article is positioned in or guided through the beam
paths between the radiation source and the detection device and the
diameter of the rod-shaped article is determined from the signals
generated in the detection device.
Inventors: |
Schroder; Dierk; (Hamburg,
DE) |
Correspondence
Address: |
VENABLE LLP
P.O. BOX 34385
WASHINGTON
DC
20045-9998
US
|
Assignee: |
Hauni Maschinenbau AG
Hamburg
DE
D-21033
|
Family ID: |
35746552 |
Appl. No.: |
11/248616 |
Filed: |
October 13, 2005 |
Current U.S.
Class: |
131/280 ;
356/638 |
Current CPC
Class: |
G01B 11/105 20130101;
G01B 11/2433 20130101; A24C 5/3412 20130101 |
Class at
Publication: |
131/280 ;
356/638 |
International
Class: |
A24C 5/34 20060101
A24C005/34 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 13, 2004 |
DE |
10 2004 049 879.2 |
Claims
1. An apparatus for measuring the diameter of a rod-shaped article,
comprising: a radiation source for generating a beam; a beam
splitter arranged to split the beam coming from the radiation
source into several component beams and to conduct the beams from
different directions onto the rod-shaped article; and a detection
device including a plurality of detectors each arranged to generate
a signal indicating a shading of a respective one of the component
beams caused by the rod-shaped article, wherein the rod-shaped
article is positioned in or guided through the beam paths between
the radiation source and the detection device and the diameter of
the rod-shaped article is determined from the signals generated in
the detection device.
2. The apparatus according to claim 1, wherein the beam splitter
conducts the component beams onto the rod-shaped article so that
each component beam is only partially shaded by the rod-shaped
article.
3. The apparatus according to claim 1, further including an
evaluation unit coupled to the detection device to determine the
diameter of the rod-shaped article based on the signals generated
by the detection device.
4. The apparatus according to claim 3, wherein the evaluation unit
includes an average-value former to form an average value from the
signals generated by the detecting means.
5. The apparatus according to claim 1, wherein the beam splitter
includes mirrors that deflect at least some of the component beams
of the main beam so such that the component beams impinge from
different directions on the rod-shaped article.
6. The apparatus according to claim 1, wherein the beam splitter
comprises at least one prism that deflects at least some of the
component beams of the main beam, such that the component beams
impinge from different directions on the rod-shaped article.
7. The apparatus according to claim 1, further including a beam
re-combination device arranged to recombine the component beams
after they impinge on the rod-shaped article into a single beam in
which the component beams are substantially parallel to each other,
wherein the detectors are essentially aligned side-by-side in a
row.
8. The apparatus according to claim 7, wherein the beam
re-combination device comprises mirrors that redirect the component
beams to the same direction.
9. The apparatus according to claim 7, wherein the beam
re-combination device comprises at least one prism that redirects
the component beams to the same direction.
10. The apparatus according to claim 1, further including an
alignment device positioned between the radiation source and the
beam splitter to substantially parallel align the beam coming from
the radiation source.
11. The apparatus according to claim 10, wherein the alignment
device comprises a collimating lens.
12. The apparatus according to claim 10, further including a
cylindrical lens arranged downstream of the alignment device.
13. The apparatus according to claim 1, wherein the radiation
source comprises a laser.
14. The apparatus according to claim 12, wherein the laser
comprises a laser diode.
15. The apparatus according to claim 1, wherein the detectors
comprise charge-coupled device elements.
16. The apparatus according to claim 1, wherein the beam is an
optical beam.
17. A method for measuring the diameter of a rod-shaped article,
comprising: generating a beam of radiation; splitting the beam into
several component beams that are conducted from different
directions onto the rod-shaped article generating separate signals
each of which indicate a shading of a respective one of the
component beams caused by the rod-shaped article; and determining
the diameter of the rod-shaped article from the signals.
18. The method according to claim 17, wherein the splitting step
includes conducting the component beams onto the rod-shaped article
so that each component beam is shaded only partially by the
rod-shaped article.
19. The method according to claim 17, further including recombining
the component beams, after impinging on the rod-shaped article, to
form a single beam in which the component beams are aligned
substantially parallel to each other.
20. The method according to claim 17, and further including forming
an average value from the signals generated by the different
component beams.
21. The method according to claim 17, further including aligning
the beam to be parallel before being split into component
beams.
22. The method according to claim 17, wherein the step of
generating a beam includes generating an optical beam.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority of German Application
No. 10 2004 049 879.2-54, filed on Oct. 13, 2004, the subject
matter of which is incorporated herein by reference. The content of
each U.S. and foreign patent and patent application mentioned below
is additionally incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to an apparatus for measuring the
diameter of at least one rod-shaped article, in particular of the
tobacco industry, with the aid of at least one preferably optical
measuring arrangement, comprising a radiation source for generating
a beam designed to irradiate the rod-shaped article, and a
detection device for generating signals to indicate the shading of
the beam caused by the rod-shaped article, wherein the rod-shaped
article can be positioned in or can be guided through the beam path
between the radiation source and the detection device and wherein
the diameter of the rod-shaped article can be determined from the
signals generated by the detection device. The invention
furthermore relates to a method for measuring the diameter of at
least one rod-shaped article, in particular of the tobacco
industry, the method comprising the steps of irradiating the
rod-shaped article with a preferably optical beam, generating the
signals indicating the shading of the beam caused by the rod-shaped
article, and determining the diameter of the rod-shaped article
from these signals.
[0003] The term "rod-shaped article of the tobacco industry" in
particular is understood to refer to cigarettes with or without
filters, filter rods, cigarillos, cigars, and other types of
smoking articles, regardless of the production stage these
articles. The term "rod-shaped article" furthermore also comprises
a continuous rod, which is present during a specific production
stage either as a complete rod section or a divided rod section,
e.g. for producing the aforementioned smoking article.
[0004] The diameter represents an essential quality feature that
must be monitored during the production of cigarettes and filters.
For this, the rod-shaped articles are generally aligned in the
direction of their longitudinal axis and are transported either
continuously or discontinuously through a measuring
arrangement.
[0005] The difficulty with obtaining precise measurements of the
diameter is that the rod-shaped articles are frequently "out of
round," meaning their cross sections perpendicular to the
longitudinal axes deviate more or less from a circular shape.
[0006] European Patent EP 0 909 537 A1 discloses a measuring
arrangement in which the radiation source generates a
parallel-focused, wide beam which is reflected by 90.degree. by a
mirror onto a detection device. The rod-shaped article extends
parallel to the mirror and at a right angle to the beam path and,
in the process, is positioned such that a portion of the beam
coming from the radiation source travels directly to the rod-shaped
article while another portion of the beam arrives on the rod-shaped
article after being reflected by the mirror. Thus, the beam
impinging on the detection device comprises two side-by-side
arranged areas of shading which represent the diameter in the form
of two cross-sectional axes arranged at a right angle to each
other. To be sure, this known measuring arrangement is also
suitable for rod-shaped articles which do not require a rotation
around their longitudinal axis or for which such a rotation is not
desirable during the operation and is thus in particular suitable
for continuous rods. However, measuring the diameter by only two
cross-sectional axes is not precise enough in many cases.
[0007] German Patent Document DE 195 23 273 A1 furthermore
describes a method and an arrangement for measuring the diameter of
a rod-shaped article, in particular a cigarette, of the tobacco
industry, wherein the rod-shaped article is rotated and subjected
to radiation during the transport through a stationary measuring
arrangement. The dimensions of the shading caused by the rod-shaped
article are detected accordingly, are converted to an electric
measuring signal, and a signal for the diameter of the rod-shaped
article is generated from several such measuring signals. To be
sure, the measuring accuracy can be increased with this known
arrangement, but the known arrangement in particular is not
suitable for measuring the diameter of a continuous rod which does
not rotate around its longitudinal axis.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide a method
and an apparatus of the aforementioned type which permits extremely
accurate diameter measurements of rod-shaped articles, without
having to subject the measuring arrangement and the rod-shaped
articles to a rotating movement and which is therefore particularly
suitable for diameter measurements on continuous rods.
[0009] The above and other objects are accomplished according to a
first aspect of the invention wherein there is provided an
apparatus for measuring the diameter of a rod-shaped article,
comprising: a radiation source for generating a beam; a beam
splitter arranged to split the beam coming from the radiation
source into several component beams and to conduct the beams from
different directions onto the rod-shaped article; and a detection
device including a plurality of detectors each arranged to generate
a signal indicating a shading of a respective one of the component
beams caused by the rod-shaped article, wherein the rod-shaped
article is positioned in or guided through the beam paths between
the radiation source and the detection device and the diameter of
the rod-shaped article is determined from the signals generated in
the detection device.
[0010] According to a second aspect of the invention, there is
provided a method for measuring the diameter of a rod-shaped
article, comprising: generating a beam of radiation; splitting the
beam into several component beams that are conducted from different
directions onto the rod-shaped article; generating separate signals
each of which indicate a shading of a respective one of the
component beams caused by the rod-shaped article; and determining
the diameter of the rod-shaped article from the signals.
[0011] The invention accordingly consists of using a corresponding
number of component beams, obtained by splitting the (main) beam
generated by the radiation source, for a plurality of diameter
measurements of the rod-shaped article. Each measurement occurs
from a different perspective since the component beams according to
the invention are guided from different directions onto the
rod-shaped article. The higher the number of component beams used
and the number of resulting measurements, the higher the precision
for determining the cross-sectional shape of the rod-shaped
article.
[0012] An advantages achieved with the invention is that the
diameter of the rod-shaped article can be determined with extreme
accuracy, in particular for rod-shaped articles that are not round
while. Another advantage is that a rotational movement of the
measuring arrangement or a rotation of the rod-shaped article
around its longitudinal axis is not required and the measurement
according to the invention therefore does not require rotating
components. The invention is therefore especially suitable for use
in cases where a rotational movement in particular is not required
or even desired for the processing, and thus the invention is
suitable, in particular, for continuous rods.
[0013] As a result of the latter, the rod-shaped article can remain
immovable during the measurement. Alternatively, it is also
conceivable and especially advantageous for the operation if the
rod-shaped article is moved continuously or discontinuously in a
longitudinal axial direction through the measuring arrangement,
wherein during one stage of the production of the rod-shaped
articles, a continuous rod can be present, which can be transported
in the longitudinal axial direction through the measuring
arrangement, either as a single continuous rod section or as
already divided continuous rod sections.
[0014] Owing to the fact that the invention permits a nearly
infinite number of diameter measurements at one and the same
location of a rod-shaped article, it is also possible to detect the
cross-sectional shape and the `out of roundness,` as well as the
minimum and maximum diameter of the rod-shaped article. The latter
is particularly important for determining whether the diameter is
still within permissible limits. The invention furthermore can be
used particularly advantageously for measuring cigarettes and
filter plugs having an elliptical cross section, so that matching
filter plugs and cigarette rods can be detected.
[0015] The beam splitter advantageously guides the component beams
onto the rod-shaped article so that each component beam is shaded
only partially by the rod-shaped article. The detection device thus
detects side-by-side arranged light-dark transitions of the
component beams, arriving from different directions on the
rod-shaped article, from which the diameter and/or thickness of the
rod-shaped article can be determined, respectively in the
directions perpendicular to the component beams.
[0016] The diameter of the rod-shaped article is generally
determined from the signals coming from the detection device in an
evaluation unit, installed downstream of the detection device. An
average-value former in the evaluation unit is preferably used to
form an average value of the signals coming from the detecting
means.
[0017] According to one exemplary embodiment, the beam splitter is
provided with mirrors which deflect at least some of the component
beams of the main beam in different directions and then onto the
rod-shaped article. As an alternative or in addition, at least one
prism can be provided with at least one mirror surface which
correspondingly deflects at least some of the component beams. The
component beams are thus separated out of the main beam with the
aid of the mirrors and/or the mirror surface(s).
[0018] It a further exemplary embodiment, there is provided a
beam-recombination device, which recombines the component beams
after they pass the rod-shaped article, so that they again form a
single beam in which the component beams are essentially arranged
parallel to each other. The detectors in this case are
substantially arranged side-by-side in a row. A particularly simple
embodiment of the detection device is possible with this design
since it is structurally very easy to combine the side-by-side
arranged detectors. The beam-recombination device is preferably
also provided with mirrors and/or at least one prism, comprising at
least one mirror surface, such that it is particularly easy to
redirect the component beams to the same direction.
[0019] A device for the substantially parallel alignment of the
beam coming from the radiation source may be provided between the
radiation source and the beam splitter. A device of this type is
particularly useful if the radiation source generates a diverging
beam, as is generally the case. Using such a device can also
simplify the splitting of the beam into component beams since only
the individual parallel sections of the main beam must be separated
out to form component beams, owing to the parallel alignment. A
device of this type is preferably provided with a collimator lens.
A cylindrical lens can furthermore be installed downstream of the
device and can be used advantageously for generating component
beams.
[0020] A laser, in particular a laser diode, can advantageously be
used as a radiation source and/or the detecting means can be
charge-coupled device elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] These and other features and advantages of the invention
will be further understood from the following detailed description
of the preferred embodiments with reference to the accompanying
drawings.
[0022] FIG. 1 shows a perspective, schematic view of a continuous
cigarette rod machine, showing the essential structural
components.
[0023] FIG. 2 shows a schematic view of a first exemplary
embodiment according to the invention of an optical measuring
arrangement with its essential components, used in the continuous
cigarette rod machine shown in FIG. 1, which is positioned at a
right angle to the longitudinal axis and movement direction of the
continuous cigarette rod.
[0024] FIG. 3 shows a schematic view of a second exemplary
embodiment according to the invention of an optical measuring
arrangement with its essential components, used in the continuous
cigarette rod machine shown in FIG. 1, which is positioned at a
right angle to the longitudinal axis and movement direction of the
continuous cigarette rod.
DETAILED DESCRIPTION OF THE INVENTION
[0025] FIG. 1 shows a schematic, perspective view of a continuous
cigarette rod machine of the type "PROTOS," manufactured by the
assignee of the present invention, in which the main components are
visible. The design and function of this continuous cigarette rod
machine are briefly described in the following.
[0026] An airlock 1 supplies a pre-distributing device 2 with
batches of tobacco. In a controlled operation, a withdrawing roller
3 of the pre-distributing device 2 is used to supplement the
tobacco in a storage container 4 from which a vertical conveyor 5
removes the tobacco. In a controlled operation, the vertical
conveyor then feeds this tobacco to an accumulation chute 6. A pin
roller 7 removes a uniform stream of tobacco from this accumulation
chute 6 and a beater roller 8 then beats the tobacco out of the
pins of the pin roller 7 and tosses the tobacco with a constant
speed onto a circulating distributing web 9.
[0027] A fibrous tobacco fleece, formed in this way on the
distributing web 9, is subsequently tossed into a sifting device 11
which essentially consists of an air curtain through which larger
and/or heavier tobacco particles pass while all other tobacco
particles are directed by the air into a funnel 14 that is formed
by a pin roller 12 and a wall 13. From the pin roller 12, the
tobacco is tossed into a tobacco channel 16 and onto a continuous
rod conveyor 17 against which the tobacco is held by air suctioned
into a low-pressure chamber 18, to form a continuous tobacco
rod.
[0028] A straightening device 19 removes excess tobacco from the
continuous tobacco rod which is then placed onto a synchronously
conveyed cigarette-paper strip 21. The cigarette-paper strip 21 is
pulled from a bobbin 22, is guided through a printing device 23,
and is then placed onto a driven format belt 24. The format belt 24
transports the continuous tobacco rod and the cigarette-paper strip
21 through a format machine 26 in which the cigarette-paper strip
21 is folded around the continuous tobacco rod, so that one edge
still sticks up. This edge is coated with glue by means of a glue
applicator, not shown herein, whereupon the glue seam is closed and
dried by means of a tandem seam smoothing iron 27.
[0029] A continuous cigarette rod 28, formed in this way, passes
through a measuring and control unit 29 and is cut into
double-length cigarettes 32 with a knife apparatus 31. The
double-length cigarettes 32 are then transferred onto a takeover
drum 36 of a filter-tipping machine 37 by means of a transfer
device 34 with controlled arms 33. On the cutting drum 38 of the
filter-tipping machine, they are cut with a circular knife into
individual cigarettes.
[0030] Conveying belts 39, 41 convey excess tobacco into a
container 42, arranged below the storage container 4, from which
the returned tobacco is removed again with the aid of the vertical
conveyor 5.
[0031] The measuring and control unit 29 of the continuous
cigarette rod machine according to FIG. 1 is provided with an
optical measuring arrangement, of which a first exemplary
embodiment 50 is shown in FIG. 2 and a second exemplary embodiment
50a is shown in FIG. 3.
[0032] The optical measuring arrangement 50 according to FIG. 2
comprises a radiation source 52, which is preferably provided with
at least one laser diode or consists of such a laser diode. The
radiation source 52 for the exemplary embodiment shown in FIG. 2 is
designed to generate a diverging beam 54a. The diverging beam 54a
is converted with the aid of a downstream-arranged collimator lens
56 to a parallel beam 54b, which then passes through a cylindrical
lens 58.
[0033] Behind the cylindrical lens 58, the parallel beam 54b, which
can be called a main beam in the same way as the beam 54a, is split
into component beams 601 to 608 that impinge from different
directions onto the continuous cigarette rod 28, such that each
component beam is shaded only partially by the continuous cigarette
rod 28. In the process, the continuous cigarette rod 28 is guided
through the optical measuring arrangement 50 so that the component
beams 601 to 608 extend approximately at a right angle to the
longitudinal axis, which extends at a right angle to the drawing
plane for FIG. 2, thus causing the component beams to extend at a
right angle to the movement direction of the continuous cigarette
rod 28.
[0034] FIG. 2 furthermore shows that the component beams 601 to 608
initially form side-by-side arranged parallel beam sections of the
main beam 54b, directly behind the cylindrical lens 58. The
component beams 601 to 608 of the exemplary embodiment are
subsequently reflected on mirrors, wherein some of the component
beams are deflected only after they impinge on the continuous
cigarette rod 28 and other component beams are deflected before
they impinge on the continuous cigarette rod 28.
[0035] The first component beam 601, the `upper` component beam in
FIG. 2, is initially deflected by 45.degree. on a mirror 621 and
onto a mirror 641, where it is deflected by 90.degree. onto the
continuous cigarette rod 28. In the same way, the adjacent second
component beam 602 is initially deflected by 45.degree. on a mirror
622 and subsequently by 90.degree. on a mirror 642 in the direction
of the continuous cigarette rod 28. While the mirrors 621 and 622
are arranged side-by-side, such that the first and second component
beams 601 and 602 continue to extend parallel following the
reflection, the two mirrors 641 and 642 are spaced apart such that
the first component beam 601 grazes one side of the continuous
cigarette rod 28 and the second component beam 602 grazes the
opposite side of the continuous cigarette rod 28. Accordingly, the
spacing between the two mirrors 641 and 642 is determined by the
thickness of the continuous cigarette rod 28. However, the
orientation of the mirrors 641 and 642 relative to each other is
identical, so that these mirrors 641 and 642 are aligned
parallel.
[0036] The third component beam 603 is reflected by 90.degree. on a
mirror 623 and subsequently impinges directly onto the continuous
cigarette rod 28. The same happens with the fifth component beams
605, which is deflected on a mirror 625. As a result, the third
component beam 603 and the fifth component beam 605 are aligned
parallel when they pass the continuous cigarette rod 28, with the
third component beams 603 grazing one side of the continuous
cigarette rod 28 and the fifth component beam 605 grazing the
opposite side of the continuous cigarette rod 28. The two mirrors
623 and 625 are accordingly spaced apart, but have the same
orientation. Thus, upon their arrival on the continuous cigarette
rod 28, the third component beam 603 and the fifth component beam
605 extend at an angle of 45.degree. relative to the first
component beam 601 and the second component beam 602.
[0037] The fourth component beam 604 and the sixth component beam
606 also form a pair and pass the continuous cigarette rod 28 at a
right angle, relative to the first component beam 601 and the
second component beam 602. For this, the fourth component beam 604
is reflected on a mirror 624 and the sixth component beam 606 is
reflected on a mirror 626 by 45.degree. in the direction of the
continuous cigarette rod 28, wherein the two mirrors 624 and 626
extend parallel to each other, but are spaced apart such that the
fourth component beam 604 grazes the continuous cigarette rod 28 on
one side and the sixth component beam 606 grazes the continuous
cigarette rod 28 on the opposite side.
[0038] In contrast to the component beams 601 to 606, the seventh
component beam 607 and the eighth component beam 608 are focused by
means of the cylindrical lens 58 directly onto the continuous
cigarette rod 28 before being reflected by the mirrors 627 and/or
628 which are installed behind continuous cigarette rod 28. The
seventh component beam 607 and the eighth component beam 608 are
spaced apart for this, such that the seventh component beam 607
grazes the continuous cigarette rod 28 on one side and the eighth
component beam 608 grazes the continuous cigarette rod 28 on the
opposite side. The spaced-apart seventh and eighth component beams
607 and 608, which are not subjected to a change in direction
before they pass by the continuous cigarette rod 28, therefore
extend at an angle of 135.degree. to the first and second component
beams 601 and 602.
[0039] For the exemplary embodiment shown herein, the parallel
component beams 601 to 608 have the same constant cross section
over their course. However, configurations with changing cross
sections for the component beams are also conceivable as well, for
example following a reflection on a mirror. It is furthermore
conceivable, in principle, to form converging or diverging beams if
necessary.
[0040] Owing to the previously described course of the component
beams 601 to 608, a partial shading of the continuous cigarette rod
28 occurs over an angular region of approximately 90.degree. for
the exemplary embodiment, wherein the shaded angular regions
overlap, as shown in FIG. 2.
[0041] Of course, the width and the spacing between component beams
can be adjusted through a corresponding configuration of the
reflecting mirrors, so as to shade an angular region of less than
90.degree.. However, the angular shading region selected for the
exemplary embodiment, which uses eight component beams for
irradiating the continuous cigarette rod 28, should not be less
than 45.degree. because undesirable gaps in the form of non-shaded
regions can otherwise develop. The angular region to be shaded
should furthermore not exceed 180.degree. to prevent an undesirable
overlapping of two parallel component beams belonging to the same
pair, thus making it difficult or even impossible to assign these
clearly.
[0042] FIG. 2 shows that the component beams directly behind the
cylindrical lens 58 are defined so that the first to the sixth
component beams 601 to 606 are positioned directly adjacent to each
other while the seventh component beam 607 is at a distance from
the sixth component beam 606 as well as at a distance from the
eight component beam 608, wherein FIG. 2 shows that the distance
respectively corresponds to the width of a component beam. The gap
between the sixth component beam 606 and the seventh component beam
607, as well as the gap between the seventh component beam 607 and
the eighth component beam 608 furthermore contains beam sections
belonging to the main beam 54a which, in the same way as the
component beams 601 to 608, represent component beams. However,
these component beams are not used further because the beam section
between the sixth component beam 606 and the seventh component beam
607 is reflected back by the mirror 641, directly onto the
cylindrical lens 58, while the beams section between the seventh
component beam 607 and the eight component beam 608 is completely
shaded by the continuous cigarette rod 28. Accordingly, the
exemplary embodiment does not make use of the complete width of the
main beam 54b for forming the relevant component beams 601 to 608.
It should be noted here that other configurations are conceivable,
of course, which use a higher or lower number of component beams
for the partial shading of the continuous cigarette rod 28. For
example, it is also possible to use all beam sections of the main
beam 54b to form the relevant component beams.
[0043] FIG. 2 furthermore shows that the individual mirrors are
configured such that their effective cross section for reflection
does not exceed the cross section of the partial beam they reflect,
so as to prevent interference between the respectively adjacent
component beam. As a result, the mirrors with the smaller
reflection angles (e.g. the mirrors 621, 622, 624, 626) have a
greater length than the mirrors with the higher reflection angles
(e.g. 623, 625, 641, 642).
[0044] In place of the discrete mirrors shown in FIG. 2, it is
furthermore possible to use an optical element having reflective
surface areas incorporated therein. Of course, it is also
conceivable to use prisms or the like in place of mirrors.
[0045] FIG. 2 and the preceding description clearly show that the
mirrors 621, 622, 623, 624, 625 and 626 also function as beam
splitters. The same is true for the mirror 627 on which the seventh
component beam 607 is reflected by an angle of 90.degree. (downward
according to FIG. 2) after it has passed the continuous cigarette
rod 28, and the mirror 628 on which the eighth component beam 608
is also reflected by 90.degree. after passing the continuous
cigarette rod 28 (downward according to FIG. 2). The mirrors 621 to
628 consequently form a beam splitter for the embodiment shown
herein.
[0046] FIG. 2 furthermore shows that the component beams 601 to 608
of the exemplary embodiment are recombined later on to form a
single beam by using additional mirrors and are then conducted to
the detector row 66. As a result of the above-described arrangement
of the mirrors 641 and 642 and after passing the continuous rod 28,
the first component beam 601 and the spaced apart, parallel second
component beam 602 are conducted at a right angle directly onto the
detector row 66. For the third component beam 603 and the parallel,
spaced apart fifth component beam 605, the mirrors 643 and 645 are
provided between the continuous cigarette rod 28 and the detector
row 66, on which these component beams are reflected by about
45.degree. before impinging at a right angle on the detector row
66. Since the fourth component beam 604 and the parallel, spaced
apart sixth component beam 606 extend approximately parallel to the
detector row 66 while passing the continuous cigarette rod 28, the
additional mirrors 644 and 646 are provided for deflecting these
partial beams by 90.degree. in the direction of the detector row
66, wherein the embodiment shown herein respectively requires two
additional mirrors 627, 647 and 628, 648 for redirecting the
seventh component beam 607 and the eight component beam 608, which
are arranged in the beam path after the continuous cigarette rod
28. Initially, the seventh and/or the eighth component beam 607
and/or 608 are reflected by 90.degree. on the mirror 627 and/or 628
(downward according to FIG. 2), before they are reflected again by
45.degree. on the mirror 647 and/or 648 in the direction of the
detector row 66.
[0047] The mirrors 641 to 648 accordingly function as a
beam-recombination device for a parallel, side-by-side alignment of
the component beams 601 to 608, such that they form a single beam
which impinges perpendicular on the detector row 66. It is apparent
from FIG. 2 that the sequence of the individual component beams 601
to 608 is different when they impinge on the detector row 66 than
when they exit the cylindrical lens 58. However, this fact does not
play a role in the determination of the diameter. Of course,
configurations with a different sequence for the component beams
are conceivable as well.
[0048] The component beams 601 to 608 for the embodiment shown
herein are deflected by 135.degree. from the start to the end of
their beam path before impinging on the detector row 66. Of course,
a different orientation for the detector row 66 is also
conceivable.
[0049] With respect to possible alternative configurations for the
mirrors 641 to 648, the same applies as previously stated for the
mirrors 621 to 628.
[0050] FIG. 3 shows a second preferred embodiment of a measuring
arrangement 50a which differs from the measuring arrangement 50
shown in FIG. 2 in that three separate prisms 72, 74 and 76 are
provided in place of discrete mirrors while the remaining
components are the same as for the embodiment of the optical
measuring arrangement 50 shown in FIG. 2. Thus, only the
differences to the first embodiment according to FIG. 2 are
described in the following for the second embodiment of the optical
measuring arrangement 50a according to FIG. 3.
[0051] The three separate prisms 72, 74, 76 are provided for
splitting the main beam and aligning and recombining the component
beams, wherein the prisms 72, 74, 76 are designed such that the
component beams enter and exit the surface areas at a ninety degree
angle to avoid diffraction effects.
[0052] In contrast to the first embodiment according to FIG. 2, the
parallel beam 54b of the second embodiment of the optical measuring
arrangement 50a, shown in FIG. 3, is divided not into eight but
into six component beams 601 to 606 behind the cylindrical lens
58.
[0053] The first component beam 601, the `top` component beam in
FIG. 3, initially enters the first prisms 72 through a first
surface 721, aligned at a right angle, is then reflected by an
opposite-arranged second surface 722 of the first prism 72,
arranged at an angle of 1200 relative to the impinging component
beam, in the direction of the continuous cigarette rod 28 and exits
the prism 72 again through a third surface 723, aligned at a right
angle, such that it grazes one side of the continuous cigarette rod
28. Following this, the first component beam 601 enters a surface
761, aligned at a right angle, of the third prism 76 and exits
again through an also right-angle aligned second surface 762 before
it impinges on the detector row 66. In the same way, the
neighboring component beam 602 is deflected by the first prism 72
and is conducted through the third prism 76, wherein the second
component beam 602 is spaced apart from the first component beam
601, such that the second component beam 602 grazes the continuous
cigarette rod 28 on its opposite side.
[0054] The third component beam 603 enters the second prism 74
through its right-angle aligned first surface 741, is reflected by
an opposite arranged second surface 742 of the second prism 74,
arranged at an angle of 1500 relative to the impinging component
beam, and exits again through its third surface 743, positioned at
a right angle to the component beam, in the direction of the
continuous cigarette rod 28, such that it grazes this rod on one
side. Subsequently, the third component beam 603 enters the third
prism 76 through a third surface 763, arranged at a right angle to
this component beam, is reflected by an opposite-arranged fourth
surface 764, positioned at a 1500 angle relative to the impinging
component beam, and exits the third prism 76 through its second
surface 762, which extends at a right angle to this component beam,
such that it arrives at the detector row 66. The fourth component
beam 604 extends parallel to the third component beam 603 and thus
follows the same course, but at a distance to the third component
beam 603 and grazes the continuous cigarette rod 28 on the opposite
side.
[0055] The fifth component beam 605 passes through the second prism
74 without being reflected by entering the second prism 74 through
its first surface 741, positioned at a right angle to the component
beam, and exits the second prism 74 again through its fourth
surface 744, which is also aligned at a right angle to the
component beam, such that it grazes the continuous cigarette rod 28
on one side. Following this, the fifth component beam 605 enters
the first prism 72 through a fourth surface 724, also positioned at
a right angle, is then reflected by its slanted second surface 722
and exits again through its fifth surface 725, arranged at a right
angle to the component beam, such that it impinges on the detector
row 66. The same course is also followed by the sixth component
beam 606, which is conducted parallel to the fifth component beam
605, but at a distance thereto, and grazes the continuous cigarette
rod 28 on the opposite side.
[0056] Similarly to the first embodiment shown in FIG. 2, the first
and second component beams 601 and 602, the third and fourth
component beams 603 and 604, as well as the fifth and sixth
component beams 605 and 606 respectively form pairs which have the
same alignment and take the same course.
[0057] FIG. 3 and the associated specification text clearly show
that the three prisms 72, 74, 76 take on the function of a beam
splitter for splitting the parallel beam 54b into several--here
six--component beams 601 to 606, which are then conducted from
different directions onto the continuous cigarette rod 28. The
prisms also function as a beam-recombination device for recombining
the individual component beams 601 to 606 in a parallel,
side-by-side alignment to form a single beam that impinges with a
ninety degree angle on the detector row 66.
[0058] With respect to additional features and characteristics,
reference is made to the description of the first exemplary
embodiment of the optical measuring arrangement 50, shown in FIG.
2, to avoid repetition.
[0059] The detector row 66 comprises several side-by-side
positioned detecting elements, wherein respectively one detecting
element is assigned to one component beam. However, it is also
conceivable to have several detecting elements which respectively
combine to form a group which is then assigned to a defined
component beam. It is advantageous if the detecting elements are
charge-coupled device elements.
[0060] The light-dark transitions of the component beams, which
impinge from different directions on the continuous cigarette rod
28, are projected side-by-side onto the detector row 66. These
light-dark transitions are indicated schematically in FIG. 2, in a
graph assigned to the detector row 66.
[0061] An evaluation unit 81 (shown in FIG. 2) which is positioned
downstream of the detector row 66 then computes the diameter of the
continuous cigarette rod 28 from the light-dark transitions,
respectively in the directions extending perpendicular to the
component beams. In this way, a precise measurement of the
thickness of the continuous cigarette rod 28 is obtained for
various angular directions. The thickness of the continuous
cigarette rod 28 can be determined over a 90.degree. range since
eight component beams 601 to 608 combined into four pairs are used
for the first embodiment shown in FIG. 2. Accordingly, the
continuous cigarette rod 28 for the first embodiment according to
FIG. 2 is measured in four different directions. FIG. 3 shows that
only six component beams 601 to 606, combined into three pairs, are
used for the second embodiment, wherein the thickness can be
determined over a 120.degree. range. For that reason, the
continuous cigarette rod 28 is measured in only 3 directions for
the second embodiment according to FIG. 3.
[0062] If the number of component beams increases, a larger number
of measurements at a smaller angle division can be realized, thus
making it possible to increase the accuracy even further. In
contrast, a reduction in the number of component beams leads to a
lower number of measurements over a larger angular distance.
[0063] Finally, the evaluation unit can also comprise an
average-value former 83 for forming the average value of the
signals from the detector row 66, so as to determine an average
value for the diameter of the continuous cigarette rod 28.
[0064] It will be understood that the above description of the
present invention is susceptible to various modifications, changes
and adaptations, and the same are intended to be comprehended
within the meaning and range of equivalents of the appended
claims.
* * * * *