Method and device quality controlling packets

0001The present invention relates to a method and device for quality controlling a packet; to a packet; and to a relative blank.

0002The present invention may be used to advantage in packing cigarettes, to which the following description refers purely by way of example.

0003Packets produced on a packing machine are normally quality controlled to determine any defects, in particular, stains, scratches, or dents; and any faulty packets are subsequently rejected.

0004In Patent <patcit id="pcit0001" dnum="US4912554A"><text>US 4,912,554</text></patcit>, a packet is fed along a path through a quality control station where television cameras acquire an image of the packet; and the image is compared with a reference image to determine whether or not the packet is to be rejected.

0005Though efficient, the known quality control system described above has been found to fall short in some respects in terms of versatility and sensitivity. In particular, whenever changes are made to the graphics (artwork, brands, and/or colours) on the outside of the packets (e.g. so-called "brand changes"), changes must also be made to the reference image. Moreover, in areas of the packet bearing complex and/or highly coloured images, defects such as scratches or dents are especially difficult to detect. In other words, the artwork and colours on the packet act as noise during detection.

0006<patcit id="pcit0002" dnum="US5877506A"><text>US 5877506</text></patcit> discloses a device, which is designed to monitor blanks and comprises a source of infrared radiation. Such a device is designed to monitor only the contours of the blanks in order to verify the supply of the correct blanks, when there is a change in the type of packaging to be manufactured, and the correct positioning of the blanks. The device disclosed in <patcit id="pcit0003" dnum="US5877506A"><text>US 5877506</text></patcit> is not designed to control the quality of the blanks and is not designed to monitor surfaces of the blanks.

0007It is an object of the present invention to provide a method and device for quality controlling a packet, designed to eliminate, at least partially, the aforementioned drawbacks, and which at the same time are cheap and easy to implement.

0008According to the present invention, there is provided a method of quality controlling packets, as claimed in Claim 1 or in any one of the following Claims depending directly or indirectly on Claim 1.

0009According to the present invention, there is also provided a device for quality controlling packets, as claimed in Claim 11 or in any one of the following Claims depending directly or indirectly on Claim 11 .

0010According to the present invention, there is also provided a packet, as claimed in Claim 16 or 17 or in any one of the following Claims depending directly or indirectly on Claim 16 or 17.

0011According to the present invention, there is also provided a blank, as claimed in Claim 22 or 23 or in any one of the following Claims depending directly or indirectly on Claim 22 or 23.

0012A number of non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Figure 1</figref> shows a view in perspective, with parts removed for clarity, of a device for quality controlling packets in accordance with the present invention;</li><li><figref idref="f0002">Figure 2</figref> shows a larger-scale section along line II-II of the <figref idref="f0001">Figure 1</figref> device;</li><li><figref idref="f0003">Figure 3</figref> shows a front view in perspective of a packet of cigarettes in accordance with the present invention;</li><li><figref idref="f0004">Figure 4</figref> shows a spread-out view of a blank by which to form the <figref idref="f0003">Figure 3</figref> packet;</li><li><figref idref="f0002 f0003">Figures 5 to 9</figref> show front views in perspective of alternative embodiments of packets in accordance with the present invention;</li><li><figref idref="f0005 f0006 f0007 f0008 f0009">Figures 10 to 14</figref> show spread-out views of blanks by which to form the <figref idref="f0002 f0003">Figure 5 to 9</figref> packets respectively;</li><li><figref idref="f0010">Figure 15</figref> shows a portion of the <figref idref="f0003">Figure 3</figref> packet and the corresponding response of a detecting device;</li><li><figref idref="f0010">Figure 16</figref> shows a front view in perspective of a damaged <figref idref="f0003">Figure 3</figref> packet.</li></ul>

0013Number 1 in <figref idref="f0001">Figure 1</figref> indicates as a whole a device for quality controlling a "rigid" packet 2 of cigarettes (<figref idref="f0003">Figure 3</figref>). Packet 2 comprises a cup-shaped body 3, and a lid 4 hinged to cup-shaped body 3. Cup-shaped body 3 comprises a front wall 5, two lateral walls 6 (only one shown in <figref idref="f0003">Figure 3</figref>), a bottom wall (now shown), and a rear wall (not shown). Lid 4 comprises a front wall 5a, two lateral walls 6a (only one shown in <figref idref="f0003">Figure 3</figref>), a top wall 7, and a rear wall (not shown). Lateral walls 6 and 6a are connected to respective front walls 5 and 5a and to the respective rear walls (not shown) by relative longitudinal edges 8. Front wall 5a and the rear wall (not shown) of lid 4 are connected to top wall 7 by relative edges 9; and front wall 5 is connected to the bottom wall (not shown) by an edge 10.

0014Packet 2 is formed from a substantially flat blank 11 (<figref idref="f0004">Figure 4</figref>) comprising a central portion 12, and a number of lateral panels 13 located symmetrically on opposite sides of portion 12. Portion 12 comprises a number of panels aligned lengthwise of blank 11; each panel 13 is connected to portion 12 by a preformed fold line 14; and, once folded, fold lines 14 correspond to edges 8 of packet 2.

0015Blank 11 has a grid 15 comprising a number of parallel longitudinal lines 16, and a number of parallel lines 17 crosswise, in particular, perpendicular, to lines 16. Lines 16 and 17 are invisible to the naked eye, and comprise special pigments detectable optically at a given wavelength outside the visible range, in particular at a wavelength in the ultraviolet range.

0016Device 1 (<figref idref="f0001">Figure 1</figref>) comprises a transfer unit 18 for feeding packet 2 along a path P through two quality control stations 19 and 20. Device 1 also comprises two conveyors 21 and 22, each having a suction belt 23 positioned on edge and looped about two vertical-axis pulleys 24. Conveyor 21 receives packet 2 from an input station 25, and feeds packet 2 through quality control station 19 to conveyor 22; and conveyor 22 feeds packet 2 through quality control station 20 to an output station 26.

0017Two detecting units 27 and 28 are located at quality control stations 19 and 20 respectively, and each comprise an optical detector 29, 30, and an electromagnetic radiation source 31. Optical detectors 29 and 30 acquire data relative to grid 15 by receiving electromagnetic radiation at said given wavelength.

0018As shown more clearly in <figref idref="f0002">Figure 2</figref>, two inclined mirrors 32 are located on opposite sides of conveyor 21 at quality control station 19, to enable optical detector 29 to analyze lateral walls 6 and 6a of packet 2.

0019Device 1 also comprises a central control unit 33 which receives the data acquired by detecting units 27 and 28, and in turn comprises a comparing unit 34 for comparing the acquired data with reference data. On the basis of the comparison between the acquired and reference data, central control unit 33 activates a known reject device 35 (shown schematically in <figref idref="f0001">Figure 1</figref>) located immediately downstream from device 1 and for eliminating any faulty packets downstream from conveyor 22.

0020In actual use, when packet 2 is located at quality control stations 19 and 20, sources 31 emit electromagnetic radiation to bring the pigments to an excited state, decaying from which the pigments themselves emit electromagnetic radiation at said given wavelength outside the visible range. At this point, optical detectors 29 and 30 detect the shape and/or position of various areas of grid 15 and/or the intensity of the electromagnetic radiation, at the given wavelength, from the areas of grid 15.

0021The electromagnetic radiation emitted by sources 31 and the aforementioned pigments may have different wavelengths. In the case the electromagnetic radiation emitted by sources 31 and the aforementioned pigments have indeed different wavelengths, as optical detectors 29 and 30 detects electromagnetic radiation at the aforementioned given wavelength, noise due to, for example, radiation simply reflected by packet 2 is disregarded; as a consequence, the detection of data is more precise.

0022The detected shape, position, and/or intensity are compared by comparing unit 34 with a reference shape, position, and/or intensity; and, in the event the difference between the detected and reference data exceeds given threshold values, central control unit 33 activates reject device 35.

0023In connection with the above, it should be pointed out that, in the event packet 2 is dented, the shape and position of detected areas of grid 15 differ from the reference shape and position of packet 2 in perfect condition; and, in the event packet 2 is scratched, the intensity of the electromagnetic radiation, at the given wavelength, of the scratched area of grid 15 is below the reference intensity. <figref idref="f0010">Figure 16</figref> shows the <figref idref="f0003">Figure 3</figref> packet 2 with a dent along edge 10, and the relative distorted grid 15.

0024Optical detectors 29 and 30 preferably each comprise known area scales for detecting electromagnetic radiation, at the given wavelength, along scan lines 36. By way of example, <figref idref="f0010">Figure 15</figref> shows an area of grid 15, and the corresponding area scale response along scan line 36. The y axis shows the position along the scan line, and the x axis the intensity of the relative pixels. In this case, the comparing unit compares the positions, heights, and/or shapes of the peaks in <figref idref="f0010">Figure 15</figref> with reference positions, heights, and/or shapes.

0025Device 1 as described above allows changes to be made to the graphics (artwork, brands, and/or colours) on the outside of packet 2 (e.g. so-called "brand changes") without changing the reference data, and also provides for accurately determining the condition of packet 2, even in areas of packet 2 bearing complex and/or highly coloured images.

0026In this connection, it should be pointed out that, since optical detectors 29 and 30 only detect electromagnetic radiation at said given wavelength outside the visible range, whatever is picked up by optical detectors 29 and 30 is unaffected by the graphics on the outside of packet 2.

0027<figref idref="f0002 f0003 f0005 f0006 f0007 f0008 f0009">Figures 5 to 14</figref> show alternative embodiments of packet 2 and relative blank 11. As can be seen, packets 2 in <figref idref="f0002 f0003">Figures 5 to 9</figref> are substantially similar to packet 2 described above, except that grid 15 is replaced by one or more given portions 37 of various forms and comprising said pigments.

0028Grid 15 is preferably stamped on blank 11 off the packing machine, i.e. at the packing material manufacturer's plant or paper mill. Alternatively, the grid may be stamped on the blank by means of a stamping device upstream from the packing machine.

0029The <figref idref="f0003">Figure 5</figref> packet 2, formed from the <figref idref="f0005">Figure 10</figref> blank, comprises one portion 37 on lateral wall 6a of lid 4. In this case, in the event the lateral panel 13 partly defining wall 6a is not glued properly and is therefore partly raised, optical detector 29 can detect portion 37 directly, and not only by means of one of mirrors 32. In <figref idref="f0003">Figures 5</figref> and <figref idref="f0005">10</figref>, portion 37 is hatched.

0030In the <figref idref="f0003">Figure 6</figref> packet 2, formed from the <figref idref="f0006">Figure 11</figref> blank 11, portion 37 extends along the edges of packet 2. As shown in <figref idref="f0006">Figure 11</figref>, portion 37 extends at least partly along the edge of blank 11. In <figref idref="f0003">Figures 6</figref> and <figref idref="f0006">11</figref>, portion 37 is hatched.

0031In the <figref idref="f0002">Figure 8</figref> packet 2, formed from the <figref idref="f0008">Figure 13</figref> blank 11, portion 37 comprises two substantially perpendicular lines on front wall 5, one extending from one longitudinal edge 8 to the other longitudinal edge 8, and the other extending from edge 9 to edge 10. In <figref idref="f0002">Figures 8</figref> and <figref idref="f0008">13</figref>, portion 37 is shown by bold lines.

0032In the <figref idref="f0002">Figure 7</figref> packet 2, formed from the <figref idref="f0007">Figure 12</figref> blank 11, portion 37 comprises two substantially perpendicular lines, a first extending on front wall 5, lateral walls 6, and the rear wall (not shown in <figref idref="f0002">Figure 7</figref>) of cup-shaped body 3, and a second extending on front walls 5 and 5a, on the bottom and rear walls (not shown in <figref idref="f0002">Figure 7</figref>) of cup-shaped body 3, and on top wall 7 and the rear wall (not shown in <figref idref="f0002">Figure 7</figref>) of lid 4. In <figref idref="f0002">Figures 7</figref> and <figref idref="f0007">12</figref>, portion 37 is shown by bold lines.

0033The <figref idref="f0003">Figure 9</figref> packet 2, formed from the <figref idref="f0009">Figure 14</figref> blank 11, has a portion 37 comprising a number of lines, which extend along the edges of packet 2, and which, from the corners, intersect on each wall 5, 5a, 6, 6a, 7, each of the rear walls (not shown), and the bottom wall (not shown). In <figref idref="f0003">Figures 9</figref> and <figref idref="f0009">14</figref>, portion 37 is shown by bold lines.

0034Though the above description and accompanying drawings relate to a conventional hinged-lid packet of cigarettes, the teachings of the present invention obviously also apply to packets of cigarettes of any type, such as a hinged-lid packet with rounded or bevelled edges, or a "soft" packet of cigarettes. The teachings of the present invention obviously also apply to cartons of packets of cigarettes, and to packets of other than cigarettes, such as packets of food products, confectionary, or toiletries.