EP1585057A1

EP1585057A1 - Method and unit for selecting and separating reams from a stack of sheets of paper or similar

Info

Publication number: EP1585057A1
Application number: EP04425263A
Authority: EP
Inventors: Gabriele Canini; Andrea Cinotti
Original assignee: KPL Packaging SpA
Current assignee: KPL Packaging SpA
Priority date: 2004-04-08
Filing date: 2004-04-08
Publication date: 2005-10-12
Also published as: US20050230899A1; CA2503990A1; BRPI0501256A; EP1585057A8

Abstract

A ream (2) is selected and separated from a stack (3) of sheets (4) by means of a separating member (16) which is inserted inside the stack (3) at an insertion region (18) defined by images acquired by a television camera (10) moved vertically to cover a given scanning region (12) of the stack (3); a focused portion (T1) of each image acquired by the television camera (10) being located as a function of the location in the image of a line (23) projected onto the stack (3) at an angle of incidence (β) of other than 90°.

Description

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.
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, 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.
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 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 α (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 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 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.
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.
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 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 α 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", 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 β 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 P1 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 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, 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.

Claims

A unit for selecting and separating reams (2) from a stack (3) of sheets (4) of paper or similar; the stack (3) comprising a number of sheets (4) stacked in a given direction (6), and having a front face (8) substantially parallel to said direction (6); the unit comprising a television camera (10) facing the front face (8) to acquire an image of a portion (8a) of the front face (8); actuating means for moving the stack (3) and the television camera (10) with respect to each other to vary the portion (8a) of the front face (8) covered by the television camera (10); separating means (16) which are inserted inside the stack (3) at a given insertion region (18) to separate a ream (2) from the stack (3); and control means (20) for counting a number of sheets (4) in the portion (8a) of the front face (8) covered by the television camera (10), and for controlling movement of the insertion region (18) in said direction (6) as a function of the number of sheets (4) counted by means of the images acquired by the television camera (10); the unit being characterized by comprising an identification device (22) for determining a focused portion (T1) of each image acquired by the television camera (10); the control means (20) modifying the analysis of the image, by which to count the sheets (4), as a function of the location of said focused portion (T1) in the image.
A unit as claimed in Claim 1, wherein the identification device (22) comprises a linear pointing device (22) for projecting onto the front face (8) of the stack (3) a line (23) striking the front face (8) at an angle (β) of other than 90°; the control means (20) analysing the images acquired by the television camera (10) to locate the projected line (23) in each image, and modifying the analysis of the image, by which to count the sheets (4), as a function of the location of the projected line (23) in the image.
A unit as claimed in Claim 2, wherein, for each image acquired by the television camera (10), the control means (20) determine the focused portion (T1) of the image as a function of the location of the projected line (23) in the image, and simply analyse the focused portion (T1) .
A unit as claimed in Claim 2 or 3, wherein, for each image acquired by the television camera (10), the control means (20) determine a distance of the relative sheet (4) from the television camera (10) as a function of the location of the projected line (23) in the image.
A unit as claimed in Claim 1, wherein the identification device (22) comprises a recognition algorithm for determining a focused portion (T1) of each image acquired by the television camera (10).
A unit as claimed in any one of the foregoing Claims, wherein the television camera (10) has an optical axis (11) at a further angle (α) of other than 90° with respect to said front face (8).
A method of selecting and separating reams (2) from a stack (3) of sheets (4) of paper or similar; the stack (3) comprising a number of sheets (4) stacked in a given direction (6), and having a front face (8) substantially parallel to said direction (6); the method comprising the steps of acquiring an image of a portion (8a) of the front face (8) by means of a television camera (10) facing the front face (8) ; moving the stack (3) and the television camera (10) with respect to each other to vary the portion (8a) of the front face (8) covered by the television camera (10); separating a ream (2) from the stack (3) at a given insertion region (18); counting a number of sheets (4) in the portion (8a) of the front face (8) covered by the television camera (10); and controlling movement of the insertion region (18) in said direction (6) as a function of the number of sheets (4) counted by means of the images acquired by the television camera (10); the method being characterized by also comprising the steps of determining a focused portion (T1) of each image acquired by the television camera (10); and modifying the analysis of the image, by which to count the sheets (4), as a function of the location of said focused portion (T1) in the image.
A method as claimed in Claim 7, and comprising the steps of projecting onto the front face (8) of the stack (3) a line (23) striking the front face (8) at an angle (β) of other than 90°; analysing the images acquired by the television camera (10) to locate the projected line (23) in each image; and modifying the analysis of the image, by which to count the sheets (4), as a function of the location of the projected line (23) in the image.
A method as claimed in Claim 8, and also comprising the steps of determining, for each image acquired by the television camera (10), the focused portion (T1) of the image as a function of the location of the projected line (23) in the image; and simply analysing the focused portion (T1).
A method as claimed in Claim 8 or 9, and also comprising the step of determining, for each image acquired by the television camera (10), a distance of the relative sheet (4) from the television camera (10) as a function of the location of the projected line (23) in the image.
A method as claimed in Claim 7, wherein the focused portion (T1) of each image acquired by the television camera (10) is determined by a recognition algorithm.