Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND UNIT FOR SELECTING AND SEPARATING REAMS FROM A
STACK OF SHEETS OF PAPER OR SIMILAR
The present invention relates to a unit for
selecting and separating reams from a stack of sheets of
paper or similar.
More specifically, the present invention relates to
a unit for selecting and separating reams from a stack of
sheets, of the type comprising a television camera
positioned facing a front face of the stack to acquire an
image of a portion of the front face; an actuating device
for moving the television camera along the stack to vary
the portion of the front face covered by the television
camera; and a separating member which is inserted inside
the stack to separate the reams successively from the
stack.
The images acquired by the television camera are
used by an electronic central control unit to control the
movement of the separating member along the stack, to
count the number of sheets in a ream during said movement
of the separating member, and to arrest the separating
member at the last sheet in the ream to be removed.
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Once positioned at the last sheet in the ream to be
removed, the separating member is moved into contact with
the stack at a given insertion region, and is inserted
inside the stack to separate the ream from the stack.
Known units of the type described above have various
drawbacks, mainly on account of the fact that, when the
front face of the stack has an undulated, other than
perfectly flat profile, and the television camera is
oriented at a given angle with respect to the front face,
to the electronic central control unit is unable to locate
the focused portion of each image acquired by the
television camera.
It is an object of the present invention to provide
a unit for selecting and separating reams from a stack of
sheets of paper or similar, designed to eliminate the
aforementioned drawbacks, and which is cheap and easy to
produce.
According to the present invention, there is
provided a unit for selecting and separating reams from a
stack of sheets of paper or similar, as claimed in Claim
1.
The present invention also relates to a method of
selecting and separating reams from a stack of sheets of
paper or similar.
According to the present invention, there is
provided a method of selecting and separating reams from
a stack of sheets of paper or similar, as claimed in
Claim 7.
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A non-limiting embodiment of the present invention
will be described by way of example with reference to the
accompanying drawings, in which:
Figure 1 shows a schematic view in perspective, with
parts removed for clarity, of a preferred embodiment of
the unit according to the present invention;
Figure 2 shows a schematic side view, with parts
removed for clarity, of the Figure 1 unit;
Figure 3 shows a schematic front view, with parts
removed for clarity, of the Figure 1 unit;
Figure 4 shows a schematic plan view, with parts
removed for clarity, of the Figure 1 unit;
Figure 5 shows a side view of a stack of sheets in
two different configurations;
Figure 6 shows a front view, with parts enlarged for
clarity, of a portion of the stack of sheets in Figure 5.
With reference to Figures 1 to 3, number 1 indicates
as a whole a unit for selecting and separating reams 2
from a stack 3 of sheets 4 supported on a pallet 5 and
comprising a number of sheets 4 stacked in a vertical
direction 6.
Unit 1 comprises an optical image-acquisition device
7 positioned facing a front face 8 of stack 3, and in
turn comprising a first slide (not shown) movable in
direction 6; a second slide (not shown) connected in
known manner to the first slide (not shown) to move
linearly in a horizontal direction 9 crosswise to
direction 6; and a television camera 10 mounted on the
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second slide (not shown), having an optical axis 11
parallel to direction 9, and for covering a portion 8a of
face 8.
Moving television camera 10 in direction 6 provides
for varying portion 8a of face 8 covered by television
camera 10, and for covering as a whole a scanning region
12 which can be illuminated by a light source 13.
In connection with the above, it should be pointed
out that direction 9 and, therefore, axis 11 form an
angle a (Figure 4) of other than 90° with face 8, which,
unless otherwise stated, will be considered a flat face
parallel to direction 6.
Obviously, in variations not shown:
television camera 10 is fixed in direction 6, and
stack 3 is movable in direction 6;
television camera 10 is mounted to scan sheets 4 by
oscillating about a given axis of rotation.
Unit 1 also comprises a separating device 14 for
separating reams 2 from stack 3, and which in turn
2o comprises a first slide (not shown) movable in direction
6; a second slide (not shown) connected in known manner
to the first slide (not shown) to move linearly in a
direction 15 perpendicular to face 8; and a separating
member 16 mounted on the second slide (not shown).
Member 16 is defined by a substantially flat, wedge-
shaped blade 17 which is inserted inside stack 3 at a
substantially spot-shaped insertion region 18 lying in
scanning region 12 of television camera 10, and whose
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location on face 8 is indicated, when blade 17 is located
a given distance from face 8, by a laser pointing device
19 integral with member 16 and for illuminating a portion
of face 8 coincident with region 18.
5 In actual use, television camera 10 is moved in
direction 6 to acquire, within scanning region 12, the
images of a number of sheets 4 normally approximating in
excess the number of sheets 4 in a ream 2. The images
acquired by television camera 10 are used by an-
electronic central control unit 20 to control the
movement of blade 17 and, therefore, of insertion region
18 in direction 6, to count sheets 4 as blade 17 moves in
direction 6, and to arrest blade 17 in direction 6 once
blade 17 is positioned at the last sheet 4 in the ream 2
to be selected and removed.
At this point, blade 17 is moved in direction 15 and
inserted inside stack 3 at region 18 to separate the ream
2 considered from stack 3.
Since television camera 10 and blade 17 are so
oriented with respect to each other that insertion region
18 lies in scanning region 12, insertion region 18 is
always located within portion 8a of face 8 covered by
television camera 10. Consequently, when blade 17 is
arrested in direction 6, insertion region 18 is always
located correctly at the last sheet 4 in the ream 2 to be
removed, regardless of the shape of sheets 4, i.e.
regardless of whether the profile of sheets 4 is
perfectly flat or undulated.
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Since face 8 may possibly be undulated, i.e. other
than perfectly flat, central control unit 20 also
provides, as television camera 10 moves in direction 6,
for continuously feedback-controlling the movement of
television camera 10 in direction 9 in response to a
signal from a distance sensor 21 integral with television
camera 10. Moving television camera 10 in direction 9
provides for maintaining a substantially constant
distance, measured parallel to direction 9, between face
l0 8 and television camera 10, and so enabling television
camera 10 to fully exploit its ability to focus the
acquired images.
As shown in Figure 4, the ability to focus the
images acquired by television camera 10 varies in
direction 15 alongside a variation in the orientation of
optical axis 11 with respect to a vertical reference
plane P perpendicular to direction 15.
That is, when optical axis 11 is parallel to
direction 15, television camera 10 is able to correctly
focus all the sheets 4 whose sides 4a facing television
camera 10 are located at most a given distance "a" from
plane P. On the other hand, when optical axis 11 is
parallel to direction 9 and, therefore, at an angle a of
other than 90° with respect to plane P, television camera
10 is able to correctly focus all the sheets 4 whose
sides 4a facing television camera 10 are located at most
at a distance which is obviously again distance "a" if
measured in direction 9, and which is a distance "b",
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greater than "a", if measured in direction 15.
For each side 4a located at most at distance "b"
from plane P, television camera 10 therefore acquires an
image having, within scanning region 12, a correctly
focused portion T1, and a blurred portion T2 (Figures 4
and 6 ) .
To locate each portion T1, central control unit 20
cooperates with a laser pointing device 22 located on the
opposite side of blade 17 to television camera 10, and
which projects onto face 8 and within scanning region 12
a line 23 striking face 8 at an angle (3 of other than 90°
(Figure 4).
As shown in Figures 4, 5 and 6, when face 8 is flat
and coplanar with plane P (as shown by the dash line in
Figure 5), line 23 intersects side 4a of each sheet 4 at
a point Pl lying in plane P (Figure 4), and is therefore
straight and parallel to direction 6 (as shown by the
dash line in Figure 6).
Conversely, when face 8 has an undulated profile (as
shown by the continuous line in Figure 5), line 23
intersects side 4a of each sheet 4 at a point P2 which is
shifted rightwards with respect to the corresponding
point P1 when side 4a projects from plane P towards
television camera 10 (Figure 4), and which is shifted
leftwards with respect to the corresponding point P1 when
side 4a is located on the opposite side of plane P to
television camera 10 (Figure 4), so that line 23 has a
curved profile (as shown by the continuous line in Figure
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g
6) .
Central control unit 20 therefore analyses the
images acquired by television camera 10 to locate line 23
in each image, and so locates relative portion T1 as a
function of the location of line 23 in the image.
Once each portion T1 is located, central control
unit 20 counts sheets 4 solely as a function of the
analysis of portions T1.
By locating line 23, sensor 21 can be eliminated,
l0 and central control unit 20 can calculate the distance of
each side 4a from plane P, and therefore from television
camera 10, either directly by means of a computing unit
within central control unit 20, or indirectly by means of
a matrix memorized in central control unit 20.
In a variation not shown, Laser pointing device 22
is replaced by a recognition algorithm implemented in
electronic central control unit 20.
