Method and device quality controlling packets

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

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

Packets 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.

In Patent US 4,912,554, 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.

Though 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.

US 5877506 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 US 5877506 is not designed to control the quality of the blanks and is not designed to monitor surfaces of the blanks.

It 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.

According 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.

According to the present invention, there is also provided a device for quality controlling packets, as claimed in Claim 13 or in any one of the following Claims depending directly or indirectly on Claim 13.

According to the present invention, there is also provided a packet, as claimed in Claim 20 or 21 or in any one of the following Claims depending directly or indirectly on Claim 20 or 21.

According to the present invention, there is also provided a blank, as claimed in Claim 26 or 27 or in any one of the following Claims depending directly or indirectly on Claim 26 or 27.

A 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>Figure 1 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>Figure 2 shows a larger-scale section along line II-II of the Figure 1 device;</li><li>Figure 3 shows a front view in perspective of a packet of cigarettes in accordance with the present invention;</li><li>Figure 4 shows a spread-out view of a blank by which to form the Figure 3 packet;</li><li>Figures 5 to 9 show front views in perspective of alternative embodiments of packets in accordance with the present invention;</li><li>Figures 10 to 14 show spread-out views of blanks by which to form the Figure 5 to 9 packets respectively;</li><li>Figure 15 shows a portion of the Figure 3 packet and the corresponding response of a detecting device;</li><li>Figure 16 shows a front view in perspective of a damaged Figure 3 packet.</li></ul>

Number 1 in Figure 1 indicates as a whole a device for quality controlling a "rigid" packet 2 of cigarettes (Figure 3). 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 Figure 3), 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 Figure 3), 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.

Packet 2 is formed from a substantially flat blank 11 (Figure 4) 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.

Blank 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.

Device 1 (Figure 1) 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.

Two 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.

As shown more clearly in Figure 2, 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.

Device 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 Figure 1) located immediately downstream from device 1 and for eliminating any faulty packets downstream from conveyor 22.

In 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.

The 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.

The 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.

In 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. Figure 16 shows the Figure 3 packet 2 with a dent along edge 10, and the relative distorted grid 15.

Optical 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, Figure 15 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 Figure 15 with reference positions, heights, and/or shapes.

Device 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.

In 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.

Figures 5 to 14 show alternative embodiments of packet 2 and relative blank 11. As can be seen, packets 2 in Figures 5 to 9 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.

Grid 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.

The Figure 5 packet 2, formed from the Figure 10 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 Figures 5 and 10, portion 37 is hatched.

In the Figure 6 packet 2, formed from the Figure 11 blank 11, portion 37 extends along the edges of packet 2. As shown in Figure 11, portion 37 extends at least partly along the edge of blank 11. In Figures 6 and 11, portion 37 is hatched.

In the Figure 8 packet 2, formed from the Figure 13 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 Figures 8 and 13, portion 37 is shown by bold lines.

In the Figure 7 packet 2, formed from the Figure 12 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 Figure 7) of cup-shaped body 3, and a second extending on front walls 5 and 5a, on the bottom and rear walls (not shown in Figure 7) of cup-shaped body 3, and on top wall 7 and the rear wall (not shown in Figure 7) of lid 4. In Figures 7 and 12, portion 37 is shown by bold lines.

The Figure 9 packet 2, formed from the Figure 14 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 Figures 9 and 14, portion 37 is shown by bold lines.

Though 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.