GB2323516A - An optical quality control unit for cigarettes. - Google Patents

Abstract

Cigarettes (2) Pass through an optical quality control unit (1) of which the essential elements are a hopper (3) with two parallel end walls (5) longitudinally encompassing at least one vertical feed channel (7) proportioned to accommodate a descending column (8) of cigarettes (2), and at least one optical sensor (4) located in alignment with an inspection station (9) afforded by one of the walls (5) in such a way as to monitor the butt ends (10) of the descending cigarettes (2); the inspection station (9) incorporates a window of hard transparent material (13).

Description

1 An optical quality control unit for cigarettes 2323516 The present

invention relates to an optical quality control unit for cigarettes. In particular, the present invention relates to an optical quality control unit for cigarettes of the type that comprises a cigarette hopper exhibiting two mutually opposed frontal walls, and a plurality of feed channels accommodating respective columns of cigarettes compassed longitudinally between the walls. The unit also comprises at least one optical sensor disposed frontally in relation to the hopper along a relative channel, occupying a position that coincides with an inspection station afforded by one of the walls, in such a way that the butt ends of the single cigarettes can be monitored optically during operation as the column drops gradually down the channel. In quality control units of the conventional type described above, the frontal walls of the hopper are fashioned generally from plexiglass or from a comparable clear vitreous material through which 2 the cigarettes can be viewed by the aforementioned optical sensor. It happens nonetheless that the internal surfaces of the walls quickly become worn and rendered opaque as a result of the interaction with the extremities of the cigarettes, which is characterized by sliding contact. This problem is accentuated by the presence of mineral particles in the materials used to manufacture the cigarettes: in effect, because the particles in question are harder than the transparent plexiglass or similar material, the inside surfaces of the walls are soon scored and optical monitoring of any kind becomes impossible. A problem of this type can be overcome by utilizing an optical quality control device of the type in question, as disclosed in US Patent nO 4 962 629, wherein the inspection station associated with each cigarette feed channel presents a through hole afforded by one of the two frontal walls at a given point along the channel, and the respective optical sensor is aligned with the hole. Such a solution brings with it a further drawback however, namely that the holes are instrumental in allowing the escape of impurities, consisting essentially in tobacco dust, which settles and ultimately will 3 build up to form a deposit on the optical sensors. To the end of ensuring that the optical sensors are freed of dust periodically, the unit disclosed in the US Patent mentioned above also incorporates a cleaning device comprising brushes, associated with and located in close proximity to the each of the optical sensors, and a drive system by which the sensors are set in motion periodically and caused to engage the corresponding brushes; accordingly, each sensor is cleaned at intervals and its optical efficiency thus restored. Whilst a quality control unit of the conventional type described above will allow cigarettes to be monitored continuously by optical sensors that are kept clean during operation, it suffers from the predominant drawback of incurring relatively high costs deriving principally from the fact that the unit comprises a significant number of components serving exclusively to clean the optical sensors and to set them in motion, also from the further drawback that frequent servicing operations are required in order to keep the brushes clean. The object of the present invention is to provide an optical quality control unit for cigarettes such as will be simple and economic constructionally, 4 and allow also of reducing the number of servicing operations to a bare minimum. The stated object is realized, according to the present invention, in an optical quality control unit for cigarettes that comprises a cigarette feed hopper presenting two frontal walls, one of which affording an inspection station; and at least one optical sensor 'Located externally of the hopper, in alignment with the inspection station, by which the cigarettes are monitored optically, characterized in that the inspection station comprises a surface embodied in a hard and transparent material, which is directed toward the inside of the hopper. The invention will now be described in detail, by way of example, with reference to the accompanying drawing which illustrates an example of embodiment enlarged and in longitudinal section. Referring to the accompanying drawing, 1 denotes an optical quality control unit for cigarettes 2, in its entirety. The unit 1 in question comprises a hopper filled with cigarettes 2, denoted 3 in its entirety, and externally of the hopper 3, at least one optical sensor 4 preferably (although not necessarily) of optoelectronic type by which the cigarettes 2 are

monitored optically. In particular, the hopper 3 comprises two vertical frontal walls 5, disposed parallel one with another, and a plurality of internal vertical baffles 6 positioned between and transversely to the walls 5 and serving thus to establish corresponding feed channels 7 down which the cigarettes 2 are caused to pass in respective columns 8. One baffle 6 and one feed channel 7 only are shown in the accompanying drawing, and whilst the following description refers only to the one feed channel 7 indicated, unless otherwise stated, it is applicable nonetheless to all the channels of the unit illustrated or otherwise. 9 denotes an inspection station afforded by one of the two walls 5, located at a given point along the feed channel 7 and in alignment with the optical sensor 4, such as will allow the cigarettes 2, and in particular one butt end 10 of each individual cigarette 2, to be viewed by the sensor 4 as they descend within the channel 7. The station 9 might extend along the relative wall 5 parallel with the channel 7 through a given distance, in which case the unit 1 could be equipped with a plurality of sensors 4 aligned vertically one with another, or alternatively the station could extend transversely

7 6 to the channel 7, covering a number of adjacent channels or even all the channels 7 of the hopper 3 simultaneously, in which case the unit 1 would use a plurality of sensors 4 aligned horizontally one with another, or again, the station could extend both longitudinally and transversely in relation to the channels 7. In the example of the drawing, the sensor 4 illustrated in bold line relates to the aforementioned case in which the station 9 extends transversely to and takes in all channels 7 of the hopper 3, or in any event to a unit 1 comprising a plurality of sensors 4 associated one with each channel 7 and disposed one alongside another; the phantom line illustration relates to the case in which the inspection station 9 extends for a given distance longitudinally along the feed channel 7 and there are two sensors 4 disposed one above the other. The station 9 comprises a socket 11 consisting in a hole 12 that passes completely through the relative wall 5, also a plug of semiprecious crystal 13 set removably into the through hole 12, consisting in a hard transparent material of which the surface 14 on the side directed in toward the feed channel 7 is rendered scratchproof by virtue of the physical 7 properties of the crystal 13. In operation, more particularly, the butt ends 10 of the cigarettes 2 pass across and brush against this same surface 14, but rather than being scuffed and rendered opaque within a short space of time, the surface 14 will instead be cleaned of any impurities that collect during the operation of the unit 1. In an alternative embodiment of the invention (not illustrated) the surface 14 could consist simply in a plate, fashioned likewise of hard and transparent material and set into a socket 11 appearing as a frontal recess, or even obtained by hardening the surface of the wall 5 locally in the neighbourhood of the inspection station 9. A person skilled in the art will have no difficulty in discerning the operation of the unit 1 from the the foregoing specification, and accordingly, no further explanation is given.

8 1 Claims

An optical quality control unit for cigarettes comprising a cigarette feed hopper presenting two frontal walls, one of which affording an inspection station; and at least one optical sensor located externally of the hopper and in alignment with the inspection station, by which the cigarettes are monitored optically, characterized in that the inspection station comprises a surface that is embodied in a hard transparent material and directed toward the inside of the hopper.

2) A unit as in claim 1, wherein the hopper comprises at least one feed channel along which a respective column of cigarettes is caused to advance, and the inspection station is located along the channel.

3) A unit as in claim 2, wherein the inwardly directed surface consists in a semiprecious crystal set into the frontal wall.

9 4) A unit as in claim 3, wherein the inspection station affords a socket internally of which the semiprecious crystal is disposed.

A unit as in claim 4, wherein the socket consists in a through hole internally of which the crystal is disposed removably and in such a way as to plug the hole entirely.

6) An optical quality control unit for cigarettes, substantially as described with reference to the accompanying drawing.