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 U.S. Pat. No. 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.
U.S. Pat. No. 5,877,506 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 U.S. Pat. No. 5,877,506 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 a packet; the method comprising a feed step to feed the packet along a feed path through a quality control station; an optical detecting step to detect at least one detected data item relative to at least one given portion of the packet; and a comparing step to compare the detected data item with at least one reference data item to determine rejection or acceptance of the packet; the method being characterized in that the given portion comprises at least a pigment, which is optically detectable at at least one given wavelength outside the visible range; the detected data item being detected by receiving electromagnetic radiation having said given wavelength from said pigment.
According to the present invention, there is also provided a device for quality controlling a packet; the device comprising at least one optical detector for optically detecting at least one data item relative to at least one given portion of the packet; and a comparing unit for comparing the detected data item with at least one reference data item to determine rejection or acceptance of the packet; the device being characterized in that the optical detector is designed to detect the detected data item by receiving electromagnetic radiation, which, in use, comes from at least a pigment of the given portion and has at least one given wavelength outside the visible range; the comparing unit being designed to elaborate said detected data item relating to said electromagnetic radiation coming from the pigment.
According to the present invention, there is also provided a packet having at least one given portion optically detectable at at least one given wavelength outside the visible range; the given portion comprising at least one first line, and at least one second line crosswise to the first line; the first and second line extending at least from a first edge to a second edge of the packet.
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:
FIGS. 5 to 9 show front views in perspective of alternative embodiments of packets in accordance with the present invention;
FIGS. 10 to 14 show spread-out views of blanks by which to form the
Number 1 in
Packet 2 is formed from a substantially flat blank 11 (
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 (
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
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
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.
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,
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.
FIGS. 5 to 14 show alternative embodiments of packet 2 and relative blank 11. As can be seen, packets 2 in FIGS. 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.
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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.
Number | Date | Country | Kind |
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BO2004A000221 | Apr 2004 | IT | national |