GB2482473A

GB2482473A - Inspection of articles

Info

Publication number: GB2482473A
Application number: GB1010891.8A
Authority: GB
Inventors: William Colton
Original assignee: Constar International UK Ltd
Current assignee: Constar International UK Ltd
Priority date: 2010-06-29
Filing date: 2010-06-29
Publication date: 2012-02-08
Also published as: WO2012001414A3; WO2012001414A2; GB201010891D0

Abstract

Means for inspecting articles comprises movement means to continuously move articles along a path past a single inspection point, a plurality of cameras each arranged to substantially simultaneously obtain an image of each article at the time it reaches the inspection point and processing means to review the images taken by the cameras to accept or reject each article and to control conveyance of each article to an accepted or rejected position. The movement means comprises gripping means. The inspection point is illuminated with one or more concave lamps. The articles are plastic bottles and in particular injection moulded performs.

Description

INSPECTION

The present invention relates to apparatus and method for inspecting articles, for example recently manufactured articles such as preforms for beverage bottles.

Bottles for the drinks industry are commonly made from plastics such as polyethylene terephthalate (PET) and high density polyethylene (HDPE).

Typically, such bottles are manufactured away from bottling plants.

However, transport of completed but empty bottles is undesirable because of the high volume of such bottles when packed.

Instead, it is common for the bottle manufacturers to provide preforms for bottles, which may be transported more efficiently to bottling plants. The preforms may then be blow moulded into finished bottles, for example at or near the bottling plant, thereby avoiding or minimising the transport of empty completed bottles.

Such a system, however, makes the provision of a suitable quality control system a challenge for bottle suppliers. In particular, it is common for bottle inspection units to be provided, for example, at the bottling plants such that bottles may be inspected for defects between blow moulding and filling.

Moreover, major drawbacks of this arrangement include the bottle inspection unit using valuable space at the bottling plant, the supply of uninspected bottles to the bottling company, the costs of transporting defective bottles to and from the bottling plant and in particular the cost of blowing or attempting to blow defective preforms.

It is accordingly desirable to provide an inspection unity capable of examining preform bottles for defects.

A further disadvantage associated with known bottle inspection units is that the inspection of each bottle may take longer than a subsequent blow moulding or preceding injection moulding or other manufacturing step. This in turn necessitates the provision of star wheels and/or large conveyor loops to store and appropriately space the bottles for inspection. Such conveyor loops take up a relatively large area of a factory. Alternatively, inspection apparatus may not examine each and every bottle passing through the plant.

Moreover, vision inspection systems of the prior art typically require preformss to be rotated and/or the provision of more than one inspection point to provide adequate inspection. This is at least in part because lighting systems are required to be positioned close to the preforms to ensure that the appearance of heavy-set walls in the images obtained from the corresponding cameras. Such appearance of heavy-set walls can prevent defects in the preforms being identified, while the position of the lights required to negate this effect prevents the positioning of cameras around the entire preform. This in turn requires the use of rotation or a second (or further) inspection point.

It is accordingly desirable to provide an inspection unit which has a reduced footprint size and/or which is able to analyse all bottles or preforms in a short space of time.

In a first aspect, the invention provides an apparatus for inspecting articles io comprising movement means to continuously move articles along a path past an inspection point, a plurality of cameras each positioned to obtain an image of each article substantially at the time it reaches the inspection point and processing means to review the images taken by the cameras to accept or reject each article and to control conveyance of each article to an accepted or rejected position.

In a further aspect, the invention provides an apparatus for inspecting articles comprising movement means to move articles along a path to and/or past an inspection point, at least one camera positioned to obtain an image of each article while at the inspection point, wherein the movement means comprises a continuous gripping means for gripping and moving the articles.

In a first aspect, the invention provides an apparatus for inspecting articles comprising movement means to continuously move articles along a path past an inspection point, a plurality of cameras each positioned to (e.g. simultaneously) obtain an image of each article substantially at the time it reaches the inspection point and processing means to review the images taken by the cameras to accept or reject each article and to control conveyance of each article to an accepted or rejected position.

In a further aspect, the invention provides an apparatus for inspecting articles comprising movement means to move articles along a path past an inspection point, at least one camera positioned to obtain an image of each article while at the inspection point, wherein the movement means comprises means for gripping each article above its centre of mass, such that each article is able to hang freely under its own weight.

In a further aspect, the invention provides an apparatus for inspecting articles comprising movement means to move articles along a path to and/or past an inspection point, at least one camera positioned to obtain an image of each article while at the inspection point, wherein the inspection point is illuminated by at least one illumination means, the illumination means comprising one or more (e.g. two or more) concave (e.g. hemispherical) lamps.

Preferably, the apparatus comprises a plurality of cameras each positioned to obtain an image of each article substantially at the time it reaches the inspection point.

Preferably, the apparatus comprises processing means to review the images taken by the cameras to accept or reject each article and to control io conveyance of each article to an accepted or rejected position.

Preferably the apparatus provides no means for rotating the articles about an internal axis at the inspection point.

is Preferably the path is in a first plane.

Preferably at least two cameras, e.g. three, four or five cameras, are arranged to receive images of an article at the inspection point in a second plane, the second plane parallel to the first plane.

Preferably the apparatus comprises a first further camera arranged to receive images of an article at the inspection point in a third plane, the third being perpendicular to the second plane.

Preferably the first further camera is provided to obtain images of the top of an article as it is held in the apparatus, e.g. the neck of a bottle preform.

Preferably the apparatus comprises a second further camera arranged to receive images of an article at the inspection point in the third plane, the second further camera positioned on the opposite side of the inspection point to the first further camera, if present.

Preferably the second further camera is positioned to receive images of the bottom of an article at the inspection point, as it is oriented in the apparatus. Preferably, the second further camera is arranged to receive images of a gate portion of an article (e.g. an injection moulded article) at the inspection point.

is Preferably the second further camera receives images of an article at the inspection point via a mirror, e.g. an angled mirror.

Preferably, one, some or all of the cameras receive images on an article at the inspection point via a mirror, e.g. an angled mirror.

Preferably, the apparatus comprises a trigger for detecting the entry of an article at the inspection point and simultaneously activating the cameras, for example via a signal to the processing means to capture images of the article.

Preferably, the trigger comprises light emission means and a corresponding light detection means, whereby a trigger signal is issued when light from the light emission means is prevented from entering the light detection means, e.g. by an article.

Preferably, the inspection point is illuminated by at least one illumination means.

Preferably, the illumination means comprises two or more concave, e.g. io substantially hemispherical, lamps capable of emitting light from their inner surfaces.

Preferably, the concave lamps comprise a concave substrate and an array of light emitting devices, e.g. light emitting diodes, arranged on their inner is surfaces.

Preferably, the inner surface of the concave substrates are substantially reflective of light, for example are white. Preferably, the light emitting devices are positioned and arranged to direct light onto the inner surfaces of the concave lamps for reflection towards the inspection point.

Preferably, the illumination means is/are positioned between the plurality of cameras and the inspection point.

Preferably, the illumination means (e.g. the concave lamps) comprises apertures corresponding to at least some of the cameras thereby allowing the cameras to receive an image of an article at the inspection point therethrough.

Preferably, the apparatus comprises on-axis lights positioned between at least some of the apertures in the concave lights and the corresponding camera.

In some embodiments, on-axis lights are provided between one, some, or all of the cameras and the inspection point.

Preferably, the on axis lights comprise a mirror for directing light from the corresponding camera to the inspection point.

Preferably, the movement means comprises a continuous gripping means for gripping and moving a plurality of articles.

Preferably, the continuous gripping means comprises a pair of elongate flexible members, e.g. chains or belts, for example endless chains or belts, arranged parallel to each other for receiving and gripping articles therebetween.

Preferably, the elongate flexible members are driven in a first direction, e.g. substantially at identical speed, thereby to move articles in a first direction.

Preferably, the speed of movement of the flexible members is controlled by the processing means, for example to ensure that the input to the apparatus is substantially matched to an output of an associated article manufacturing device.

In some embodiments, the flexible members may be driven in a first direction at different speeds, thereby effecting a rotation of the articles.

Preferably, the elongate flexible members are driven by a pulley system, e.g. a motorised pulley system.

Preferably, a distance between the parallel elongate flexible members is adjustable to enable the gripping of articles of different sizes.

Preferably, the apparatus is divided into two parts, each part comprising one of the elongate flexible members along a peripheral edge thereof, the peripheral edges of the parts being arranged substantially parallel to each other, wherein the two parts are movable towards and away from each other to adjust the size of a gap therebetween and a corresponding gap between the elongate flexible members.

Such an adjustment may, for example, beneficially provide means for gripping articles of different sizes between the elongate flexible members.

Preferably, the elongate flexible members comprise a gripping surface and a bearing surface opposite thereto. Preferably, the bearing surfaces bear against elongate bearings, for example running substantially the length of the peripheral edges of the parts of the apparatus.

Preferably, the elongate bearings comprise a plastics material, e.g. nylon or poly(tetrafluoroethylene) (PTFE).

Preferably the size of the gap between the peripheral edges of the two parts is adjustable by means of at least one adjustment means, e.g. two, three, four or more, lead screws between the two parts, e.g. running substantially perpendicular to the gap between the two parts.

Preferably the lead screw or screws is adjustable by means of a manual or is automatic crank. In some embodiments, the crank may be controlled by the processing means e.g. via a servo control.

Preferably an inclined part system is positioned to feed in articles to a lead in portion of the elongate flexible members.

Preferably the inclined part comprises means for supporting articles beneath a protruding portion, e.g. a protruding rim.

Preferably the inclined part comprises means for orienting articles to ensure that the protruding portion is aligned to be received on the supporting means at a point of entry onto the inclined part. Such orientation means may comprise, for example, robotic systems and/or rollers.

Preferably the supporting means comprises a pair of inclined rails.

Preferably the processing means comprises a computer for running an algorithm for processing the images captured by the cameras and accepting or rejecting the article.

io Preferably the apparatus comprises a barrier for diverting rejected articles to the rejected position.

Preferably the barrier is movable upon a signal from the processing means, to allow an article to pass to the accepted position. Alternatively the is apparatus comprises a barrier for diverting accepted articles to the accepted position.

Preferably the barrier is movable upon a signal from the processing means to allow an article to pass to a rejected position.

Alternatively, an ejection means, such as an air rejection device may be provided for diverting articles to the accepted and/or rejected position.

Preferably the apparatus comprises a manufacturing device for manufacturing articles, preferably preforms for thermoplastic bottles. In some embodiments, the manufacturing device includes a grinding device for grinding rejected articles.

Preferably the manufacturing device is connected to the orientation means of the inclined part by means of a conveyor, e.g. an elevator conveyor such as a stepped or inclined conveyor.

Preferably the rejected position comprises or is connected to the manufacturing device, such that the materials comprising rejected articles io may be reused to manufacture further articles.

In a further aspect, the invention provides a method for inspecting articles, e.g. preforms for thermoplastic bottles, the method comprising: * continuously conveying articles past an inspection point; * capturing (e.g. simultaneously capturing) a plurality of images of each article at the inspection point; * examining the images (e.g. automatically examining the images) for defects in each article; * passing articles having no or acceptable defects to an accepted position and passing articles having unacceptable defects to a rejected position.

Preferably the articles are injection-moulded articles each having a gate portion, wherein at least one of the images captured of each article at the inspection point includes a view of the gate portion.

In a further aspect, the invention provides a method for inspecting injection moulded preforms (e.g. thermoplastic injection moulded preforms) for containers, the method comprising: * conveying articles to and/or past an inspection point; * capturing an image of the gate of each article at the inspection point; * examining the images (e.g. automatically examining the images) for defects in each article; passing articles having no or acceptable defects to an accepted position and passing articles having unacceptable defects to a rejected position.

Preferably, the difference in pressure in a region inside the article to a region immediately outside the article or preform at the inspection point is substantially zero.

Figure 1 shows an inspection apparatus; Figure 2 shows a view of an output end of an inspection apparatus; Figure 3 shows an internal view of an inspector according to the present invention; Figure 4 shows a schematic diagram of a preform for a bottle; Figure 5 shows a plan view of an inspection zone of an inspector; Figure 5A shows a schematic diagram of an on-axis light; Figure 6 shows a perspective view of an inspector; Figure 7 shows a view of an output end of an inspection apparatus; Figure 8 shows a photograph of a side view of a preform, as captured by an inspector according to the invention; Figure 9 shows photograph of a top view of a preform, as captured by an inspector according to the invention; Figure 10 shows a photograph of a bottom/gate view of a preform, as captured by an inspector according to the invention.

Referring to Figure 1, an injection machine 102, for injection-moulding bottle preforms from e.g. PET, as a conveyor outfeed 104 connected to a hopper 106 for receiving such preforms. The conveyor outfeed 104 may comprise, for example, a robotic system for loading the preform 124 into the hopper 106. Typically, the injector system 102 comprises an array of moulds, in which the preforms are made. The robotic system comprises a corresponding array of members which may be e.g. simultaneously pushed into the moulds to remove the preforms therefrom and deposit them into the hopper 106.

In turn, the hopper 106 has an output connected to an elevator conveyor 108 which is oriented to convey preforms from the hopper 106 up to an orientation means 110 for correctly orienting the preforms for inspection.

The elevator conveyor 108, as is understood by those skilled in the art, comprises a series of platforms attached to a conveyor belt, upon each of which platforms one or more preforms may be held.

The orientation means 110 may comprise, for example a robotic system for gripping and correctly orienting the preform. Alternatively, the orientation means 110 comprises roller or screw type orientators as are known in the art. A series of photocells (not shown) in the orientation means is arranged to detect the quantity of preforms 124 held therein and feed such information back to the elevator conveyor 108 thereby to instruct it to io provide or stop providing a further input of preforms 124.

An inclined part 112 connects the orientations means 110 to an inspector 114 for inspecting the preforms. A nylon or PTFE coating on the rails, which may be additionally lubricated, provides a low coefficient of friction and enables the preforms to slide easily down the rails, thereby requiring a smaller angle of incline than might otherwise be required.

The rails of the inclined part 112 may be adjusted to be closer or further apart by a pair of lead screws (not shown) operable by means of a crank (not shown) which may be manually or automatically operated.

The inclined part may also include a guide rail (not shown) positioned above the gap between the rails to prevent the preforms being removed or from becoming misaligned while on the inclined part.

A reject bin 116 sits beneath the inspector 114 for receiving preforms rejected therefrom, while a movable outfeed conveyor 118 provides a passage for preforms from the inspector 114 to a first output box 120.

As may be seen in Figure 2, a second output box 122 may be provided adjacent the inspector 114, such that the output conveyor 118 may swing between positions to provide preform from the inspector 114 to both the first 120 and the second 122 output boxes.

io Figure 3 shows the internal workings of the inspector 114.

As can be seen, the inclined part 112 is arranged to transport preforms 124 by holding them beneath their neck support rings 124a. Indeed, the orientation means 110 is arranged to ensure that all preforms 124 are is introduced to the inclined part 112 in the appropriate alignment.

Where the inclined part 112 meets the inspector 114, a feed system 116 is provided. Typically, a short gap (e.g. a horizontal section of rails) exists between the end of the inclined part 112 and the feed system 116, where the preforms are free to orient themselves under their own weight and are fed into the feed system by the weight of those behind.

The feed system 116 includes a pair of parallel rubber backed belts 128 which run across the inspector 114 from adjacent the inclined part 112 through an inspection zone 130 to a second set of pulleys 132 at an outfeed point 134. The first belt 128a is driven by a first set of pulleys 126a and the second belt 128b is driven by a second set of pulleys 132. Each set of pulleys 126a, 132 is in turn driven by a motor 133, ensuring that the parallel belts 128 may be kept in motion to urge preforms 123 therealong.

The belts 128 are toothed to ensure a good contact with the pulleys 126a, 132.

The belts 128 are each backed by and arranged to slide over nylon strip bearings (not shown) which runs the entire length of the inspector 114 to io ensure that the belts 128 are able to exert sufficient force onto the preforms 124 to grip them.

Figure 4 shows a schematic diagram of a preform 124 being transferred from the grasp of the inclined part 112, which holds the preform beneath its neck support ring 124a, and the rubber backed belts 128 of the feed system 126, which hold the preforms 124 by the thread section 124b of the neck 124c.

A particular advantage of the arrangement of using the parallel belts 128 to grip the preforms 124 is that the preforms 124 are essentially free to orient themselves under the force of gravity before they are picked up by the belts 128 and thereby maintain a consistent position for inspection. Essentially, as each preform 124 has (or should have) the same absolute mass and weight distribution, each should be aligned identically, enabling a consistent inspection for defects. Moreover, if a preform 124 is not aligned and oriented as expected, it may be regarded as an indication of a defect.

It is also an advantage of the use of the belts 128 as a feed system 126 that the speed of movement of the belts 128 may be easily varied in order to control the spacing between each preform 124 as it is fed from the inclined part 112.

The inspection zone 130 is shown in isolation from the rest of the inspector 114 in plan view in Figure 5 and in perspective view in Figure 6.

Monitoring the inspection zone are three cameras 134, 136, 138 in a horizontal plane of the inspector 114, i.e. in a plane parallel to the plane of the parallel belts 128. These horizontal plane cameras 134, 136, 138 are is arranged at the vertices of an equilateral triangle and are inwardly facing of that triangle to point towards its circumcentre, where is positioned an inspection point 140.

The inspection point 140 is substantially encapsulated by a pair of hemispherical lights 150, 152, which emit light from their internal surface.

The hemispherical lights 150, 152 preferably each comprise an array of white light emitting light emitting diodes (LED5) arranged around their rims 154, 156, with a reflective, e.g. white inner surface to reflect light inwardly, though as would be understood by those skilled in the art, alternative lighting systems may be used to similar effect.

The rims 154, 156 of the hemispherical lights 150, 152 are arranged directly opposite and parallel to each other either side of the inspection point 140 and parallel belts 128 such that a vertically aligned gap 158 is provided therebetween.

Holes (not shown) are provided in the hemispherical lights 150, 152 to allow passage of light from the inspection point to the horizontal plane cameras 134, 136, 138. While these holes may be detrimental to even light io distribution within the inspection zone 130, each of the horizontal plane cameras 134, 136, 138 is provided with on-axis lights 142, 144, 146, which are positioned immediately adjacent the holes. These on-axis lights 142, 144, 146 provide additional corrective lighting, thereby ensuring even light distribution in the inspection zone 130.

The on-axis lights are shown in more detail in Figure 5A.

The lights 142 comprise a mounting 142a having a camera aperture 142b, positioned to view through the housing 142a to a viewing aperture 142e opposite the camera aperture 142b, the viewing aperture 142e for positioning adjacent a hole (not shown) in a hemispherical light 150, 152.

A lighting aperture or light 142d is provided in all adjacent sides of the housing 142a to the camera aperture 142b. A mirror 142c, having an aperture (not shown) to allow the camera 134 to view therethrough, is positioned to reflect light out through the viewing aperture 142e.

In particular, the ambient and substantially constant light that is provided over the surface of the preform by the hemispherical lights and the on-axis lights provides images which do not include the appearance of heavy-set walls as was associated with the prior art. This ensures that any defects which may be masked by such appearance are more easily identified, without any requirement for a second inspection point, thereby reducing the io analysis time and the footprint of the apparatus 100.

A first vertically aligned camera 150 is provided above the vertically aligned gap 158 and is arranged to view the inspection point 140 with additional lighting usually provided by a ring-shaped light (not shown) positioned is around the lens of the camera 150.

A second vertically aligned camera 162 is positioned beneath the hemispherical lights 150, 152 and is offset to one side. A 45° mirror 164 is provided directly beneath the vertically aligned gap 158 to allow the second vertically aligned camera 162 to view the inspection point 140. In particular, this arrangement allows the reject bin 116 to be held under the inspector 114, thereby reducing the footprint.

Referring again to Figure 3, a trigger sensor 166 is provided at the inspection zone 130 in order to monitor arrival of a preform 124 at the inspection point 140. The trigger sensor 166 typically comprises a laser or other light emitting device provided generally at the inspection point 140 and corresponding reflector and sensor. The light source, sensor and reflector were positioned such that a beam of light is broken by the leading edge of the neck of a preform 124 as the preform 124 reaches the inspection point 140.

The trigger sensor 166 activates all five cameras 134, 136, 138, 160, 162 simultaneously, thereby ensuring accurate and consistent visioning of the io preform 124 from all directions.

A computer (not shown) is provided to control the cameras 134, 136, 138, 160, 162 and to receive and process the images they produce at a sufficiently high speed to keep up with the throughput of preforms 124.

Referring now to Figure 7, a rejection/acceptance zone 168 is provided downstream of the inspection zone 130 at the outfeed point 134 of the feed system 126.

At the outfeed point 134, is provided a pair of reject gates 172, controlled by pneumatic actuators 174 in turn controlled by the computer (not shown) and powered by a motor 177 positioned close by. If the gates 172 are shut, e.g. if an approaching preform 124 is rejected, the preform 124 is deflected down a chute (not shown) and into the reject bin 116. In some embodiments, it is envisaged that a direct feed (not shown) between the reject bin 116 and a regrind apparatus (not shown) is provided, thereby to allow the easy reuse of the materials of rejected preforms.

However, if the gates 172 are open, e.g. if an approaching preform 124 is found to be in acceptable condition, the preform 174 is able to pass through the gates 172 to meet an outfeed chute 176, down which it may roll onto the movable outlet conveyor 118 to be deposited in one of the output boxes 120, 122.

Of course, it is envisaged that separate but connected processing means may be provided to analyse the images and control of the apparatus 100.

Referring again to Figure 3, it is preferred that the chassis 115 of the inspector 114 is provided in two halves 178, 180.

The first half 178 of the chassis 115 includes one hemispherical light 152, two horizontally arranged cameras 134, 136 and one rubber backed belt 128. The second half 180 of the chassis 115 includes the other hemispherical light 150, the third horizontally arranged camera 138 and the other rubber backed belt 128.

As can be seen in Figure 3, the two halves 178, 180 of the chassis 115 are arranged such that the parallel rubber backed belts 128 each run along adjacent peripheral edges of the halves 178, 180 in order that a space is provided therebetween for the preforms 124 to pass through.

The two halves 178, 180 of the chassis 115 are joined together by an adjustable rig 182, which rig 182 may be adjusted by the turning of parallel lead screws 184a, 184b by actuation of a crank handle 186, which is directly connected to one of the lead screws 184a. The other lead screw 184b is turned by means of a toothed belt 184c held taught around gear portions 184d, 184e of each of the lead screws 184a, 184b. Of course, the skilled person understands that any such actuation means, whether manual or automatic, may be equally appropriate.

The adjustable rig 182 thereby allows the space between the two halves 178, 180 to be increased or decreased, and accordingly the space between the parallel belts 128 to be adjusted, allowing the inspector 114 to be used to inspect preforms 124 having different neck and/or absolute dimensions.

Of course, it is important that the first vertically aligned camera 160, the 45° mirror 164 and the trigger sensor 166 remain in a constant position relative to the inspection point 140. These components are therefore mounted on a bridge 188 which spans the rig 182 parallel to the parallel belts 128. As would be recognised by one skilled in the art, it is also necessary that the inclined part 112 remains centrally aligned with the feed system 126.

The expandable bridge 188 comprises a pair of bridge members 188a, 188b, each being mounted on the outer housing of the inspector 114., parallel to the rubber back belts 128.

The lower portions of the bridge members 118a, 188b slidably rest atop the rig 182, such that they remain still as the rig 182 is expanded.

In use, the crank 186 is adjusted to ensure that the inspector 114 is set up for the appropriate dimension of preform 124.

Preforms 124 which are made by the injection machine 102 are passed onto the conveyor outfeed 104 and onward to the hopper 106.

The preforms 124 are then collected by the elevator conveyor 108 and is raised to the level of the orientation means 110. The orientation means rights the preforms 124 to be loaded onto the inclined part 112 such that they are held beneath their neck support rings 124a.

The preforms 124 are then moved down the inclined part 112 and introduced to the feed system 126, where the parallel belts 128 grip the thread portion 124b of the neck 124c of each preform 124, thus allowing each preform to hand under its own weight. The speed of movement of the parallel belts 128 is, of course, variable as the user requires, however, a preferred speed allows 6 to 7 preforms 124 to move past the inspection point 140 in a second.

As the preform 124 reaches the inspection point 140, its approach is detected by the trigger sensor 166, which sends a corresponding signal to the computer (not shown).

All five cameras 134, 136, 138, 160, 162 are simultaneously activated by the computer, when it has received the signal from the trigger sensor 166, such that the cameras 134, 136, 138, 160, 162 obtain images of the preform 124 which are then sent to the computer (not shown) for io processing.

The three horizontally aligned cameras 134, 136, 138 ensure that the full 360° aspect of the preform body is inspected to check for defects, the hemispherical lights 150, 152 including the on-axis lights 142, 144, 146 is ensuring even light distribution thereover. An example of an image obtained by the horizontally aligned cameras 134, 136, 138 may be seen in Figure 8.

The first vertically aligned camera 160 allows for inspection of the neck 124c of the preform 124, ensuring that, for example, colour and finish are acceptable. An optional ring light (not shown) may be used in the inspection zone 130 to further illuminate the neck 124c of the preform 124.

Moreover, the image includes a blurred image of the base of the preform 124, which can be used to produce an average colour reading for checking against a desired colour reading.

An example of an image obtained by the first vertically aligned camera 160 may be seen in Figure 9.

The second vertically aligned camera 162 is used, via the 45° mirror 164, to inspect the preform's 142 gate, i.e. the point at which injection of the preform 124 took place. In particular, it is important to check for the appearance of pin holes or other associated weaknesses, which may prevent successful blow-moulding of the preform or reduce the quality of io any resultant bottle. An example of an image obtained by the second vertically aligned camera 162 may be seen in Figure 10, where the gate 125 may clearly be seen.

The images are fed back from the cameras 134, 136, 138, 160, 162 to the is computer (not shown), which, via a series of one or more algorithms, analyses each image and determines whether the preform 124 is of an

acceptable quality.

The algorithm compares the images to so-called "trained images" of ideal preforms 124 which have been previously uploaded to the computer. This enables the computer to identify specks, blemishes and other signs of damage in the walls of the preform, measure the length of the gate and identify the presence of a pin hole at the gate, e.g. by identifying a white spot in the image. The colour of the preform may also be measured, as described above.

The use of the cameras 134, 136, 138, 160, 162 and the corresponding computer (not shown) alone to assess the quality of the recently manufactured preforms 124, in particular the use of the second vertically aligned camera 162 to assess the condition of the gate 125 of the preforms 124, rather than, for example creating a pressure differential between the inside and outside of a bottle or preform therefore as is known in the prior art, provides a notable advantage. As the preform 124 is not required to be stopped to insert, say, a means for increasing or reducing the pressure inside it, the throughput of the inspection apparatus 100 may more easily be matched to the output of the injection device 102. This provides a

simpler and cheaper system than the prior art.

If the preform 124 fails, the computer (not shown) does not instruct the is pneumatic actuators 174 to open the gates 172 and the preform is deflected into the reject bin 116. As noted above, the reject bin 116 may be connected by means of a feed (not shown) to a regrind machine (not shown) to allow the rejected preforms 124 to be recycled. Of course, it is also possible to provide a means to move batches of preforms 124 from the reject bin 116 to the injector device 102, for example by performing the operation manually.

However, if the preform 124 is of acceptable quality, the computer (not shown) instructs the pneumatic actuators to open the gates 172 and the preform 124 is passed into one of the output boxes 120, 122 for delivery to a bottling plant. In preferred embodiments, the outfeed conveyor 118 feeds preforms 124 into the first output box 120 until that box 120 is full, wherein the outfeed conveyor 118 is swung across to feed preforms 124 into the second output box 122. The first output box 120 may then be emptied or replaced without spillage of preforms 124 so stopping the operation of the apparatus.

As the throughput of the inspection apparatus 100 may be controlled to be substantially equal to the output of the injection device 102, it is not io necessary to provide means, such as large lead-in loops, to slow the flow of preforms through the apparatus 100. While this clearly eliminates the manufacturing bottle-neck associated with prior art devices, there are further advantages associated with being able to so closely couple an inspector 114 with an injection device 102. For example, as well as the is easy ability to recycle rejected preforms 124, if several consecutive preforms 124 (or indeed a significant number of preforms 124 within a certain number) are found to be defective, the injection device 102 may be halted to investigate if any problems existing therein are responsible for the deterioration in quality. In such a circumstance, the close coupling of the inspector 114 and the injection device 102 means that the problems are identified early and thus only a small number of preforms 124, i.e. those that have yet to be inspected, may be wasted. Moreover, it is possible to pre-emptively stop the apparatus if it becomes apparent that quality (such as colour) is deteriorating and/or to isolate defective mould carriers.

It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the spirit and scope of the claims appended hereto.

For example, it is envisaged that a timing device, such as a gate, star-wheel or scroll-wheel to load articles (e.g. preforms) onto the parallel belts in order to provide a reproducible distance between the preforms loaded onto the belts.

Moreover, it is envisaged that a robotic system may be provided to remove articles (e.g. preforms) from a manufacturing device and deposit them straight onto an inclined part or onto a series of parallel lanes for feeding onto the inclined part, thereby maintaining the correct orientation and negating the requirement for a separate orientation means.

It is also envisaged that the processing means may store information about the articles so inspected, whether accepted or rejected, for example relating to the colour, wall thickness or gate length of the articles and/or the time and date of inspection. Such information may be used to optimise (e.g. automatically optimise) and/or alter manufacturing conditions, for example in response to a change in the assessed quality of the articles. Such information may, additionally or alternatively, be transmitted to data storage devices in the accepted or rejected positions (e.g. palettes or storage bins), to record the data for future reference. Of course, such storage devices may include printed or written labels as well as RF devices.

It is further envisaged that rather than disposing of or regrinding any rejected articles, such articles may be passed for a second analysis to ensure that the articles are in fact defective.

In some embodiments, the belts may be replace by, for example, chains which may include a pad or other such gripping means attached to some or all of the links.

Claims

Claims 1. An apparatus for inspecting articles comprising movement means to continuously move articles along a path past a single inspection point, a plurality of cameras each arranged to substantially simultaneously obtain an image of each article substantially at the time it reaches the inspection point and processing means to review the images taken by the cameras to accept or reject each article and to control conveyance of each article to an accepted or rejected position.
2. An apparatus for inspecting articles comprising movement means to move articles along a path to and/or past an inspection point, at least one camera positioned to obtain an image of each article while at the inspection point, wherein the movement means comprises at least two opposed continuous gripping means for gripping and moving the articles and processing means to review the images taken by the cameras to accept or reject each article and to control conveyance of each article to an accepted or rejected position.
3. An apparatus for inspecting articles comprising movement means to continuously move articles along a path past an inspection point, a plurality of cameras each positioned to simultaneously obtain an image of each article substantially at the time it reaches the inspection point and processing means to review the images taken by the cameras to accept or reject each article and to control conveyance of each article to an accepted or rejected position.
4. An apparatus for inspecting articles comprising movement means to move articles along a path to and/or past an inspection point, at least one camera positioned to obtain an image of each article while at the inspection point, wherein the inspection point is illuminated by at least one illumination means, the illumination means comprising one or more concave lamps and processing means to review the images taken by the camera to accept or reject each article and to control conveyance of each article to an accepted or rejected position.
5. An apparatus according to Claim 2 or Claim 4, comprising a plurality of cameras each positioned to obtain an image of each article is substantially at the time it reaches the inspection point.
6. An apparatus according to any preceding Claim, wherein the path is in a first plane and wherein at least two cameras, e.g. three, four or five cameras, are arranged to receive images of an article at the inspection point in a second plane, the second plane parallel to the first plane.
7. An apparatus according to Claim 6, comprising a first further camera arranged to receive images of an article at the inspection point in a third plane, the third being perpendicular to the second plane.
8. An apparatus according to Claim 7, wherein the first further camera is provided to obtain images of the top of an article as it is held in the apparatus, e.g. the mouth of a bottle preform.
9. An apparatus according to Claim 7 or Claim 8, wherein the first further camera is provided to obtain information related to the colour of the article, for example the colour of a base of a bottle preform, such as when viewed through the mouth of a preform.
10. An apparatus according to any of Claims 6 to 9 comprising a second further camera arranged to receive images of an article at the inspection point in the third plane, the second further camera positioned on the opposite side of the inspection point to the or a first further camera, if present.
11. An apparatus according to Claim 10, wherein the second further camera is positioned to receive images of the bottom of an article at the inspection point, as it is oriented in the apparatus.
12. An apparatus according to Claim 10 or Claim 11, wherein the second further camera is arranged to receive images of a gate portion of an article (e.g. an injection moulded article) at the inspection point.
13. An apparatus according to any of Claims 10 to 12, wherein the second further camera receives images of an article at the inspection point via a mirror, e.g. an angled mirror.
14. An apparatus according to any preceding Claim, wherein, one, some or all of the cameras receive images on an article at the inspection point via a mirror, e.g. an angled mirror.
15. An apparatus according to any preceding Claim, comprising a trigger io for detecting the entry of an article at the inspection point and simultaneously activating the cameras, for example via a signal to the processing means to capture images of the article.
16. An apparatus according to Claim 15, wherein the trigger comprises light emission means and a corresponding light detection means, whereby a trigger signal is issued when light from the light emission means is prevented from entering the light detection means, e.g. by an article.
17. An apparatus according to any of Claims 1 to 3 or 5 to 16, wherein the inspection point is illuminated by at least one illumination means.
18. An apparatus according to Claim 17, wherein the illumination means comprises two or more concave lamps capable of emitting light from their inner surfaces.
19. An apparatus according to Claim 4 or Claim 18, wherein the concave lamps comprise a concave substrate and an array of light emitting devices, e.g. light emitting diodes, arranged on their inner surfaces.
20. An apparatus according to Claim 19, wherein the inner surface of the concave substrates are substantially reflective of light and the light emitting devices are positioned and arranged to direct light onto the inner surfaces of the concave lamps for reflection towards the inspection point.
21. An apparatus according to any of Claims 4 or 17 to 20, wherein the illumination means is/are positioned between the plurality of cameras and the inspection point.
22. An apparatus according to Claim 21, wherein the illumination means comprises apertures corresponding to at least some of the cameras thereby allowing the cameras to receive an image of an article at the inspection point therethrough.
23. An apparatus according to Claim 22, wherein the apparatus comprises on-axis lights positioned between at least some of the apertures in the concave lights and the corresponding camera.
24. An apparatus according to Claim 23, wherein on-axis lights are provided between one, some, or all of the cameras and the inspection point.
25. An apparatus according to Claim 23 or Claim 24, wherein the on axis lights comprise a mirror for directing light from the corresponding camera to the inspection point.
26. An apparatus according to any of Claims 1 or 3 to 25, wherein the io movement means comprises a continuous gripping means for gripping and moving a plurality of articles.
27. An apparatus according to Claim 3 or Claim 26, wherein the continuous gripping means comprises a pair of elongate flexible members, e.g. chains or belts, for example endless chains or belts, arranged parallel to each other for receiving and gripping articles therebetween.
28. An apparatus according to Claim 27, wherein the elongate flexible members are driven in a first direction, e.g. substantially at identical speed, thereby to move articles in a first direction.
29. An apparatus according to Claim 27 or Claim 28, wherein the speed of movement of the flexible members is controlled by the processing means, for example to ensure that the input to the apparatus is substantially matched to an output of an associated article manufacturing device.
30. An apparatus according to Claim 27 or Claim 28, wherein the flexible members may be driven in a first direction at different speeds, thereby effecting a rotation of the articles.
31. An apparatus according to any of Claims 27 to 30, wherein the elongate flexible members are driven by one or more pulley systems, e.g. motorised pulley systems.
32. An apparatus according to any of Claims 27 to 31, wherein a distance between the parallel elongate flexible members is adjustable to enable the gripping of articles of different sizes.
33. An apparatus according to Claim 32, wherein the apparatus is divided into two parts, each part comprising one of the elongate flexible members along a peripheral edge thereof, the peripheral edges of the parts being arranged substantially parallel to each other, wherein the two parts are movable towards and away from each other to adjust the size of a gap therebetween and a corresponding gap between the elongate flexible members.
34. An apparatus according to any of Claims 27 to 33, wherein the elongate flexible members comprise a gripping surface and a bearing surface opposite thereto.
35. An apparatus according to Claim 34 the bearing surfaces bear against elongate bearings.
36. An apparatus according to Claim 35, wherein the elongate bearings comprise a plastics material, e.g. nylon or poly(tetrafluoroethylene) (PTFE).
37. An apparatus according to any of Claims 33 to 36, wherein the size of the gap between the peripheral edges of the two parts is adjustable by means of at least one adjustment means, e.g. two, three, four or more, lead screws between the two parts, e.g. running substantially perpendicular to the gap between the two parts.
38. An apparatus according to Claim 37, wherein the lead screw or screws is adjustable by means of a manual or automatic crank.
39. An apparatus according to any preceding Claim compring an inclined part system is positioned to feed in articles to a lead in portion of the movement means.
40. An apparatus according to Claim 39, wherein the inclined part comprises means for supporting articles beneath a protruding portion, e.g. a protruding rim.
41. An apparatus according to Claim 39 or Claim 40, wherein the inclined part comprises means for orienting articles to ensure that the protruding portion is aligned to be received on the supporting means at a point of entry onto the inclined part.
42. An apparatus according to Claim 41, wherein the orientation means comprises a robotic system and/or rollers.
43. An apparatus according to any of Claims 40 to 42, wherein the supporting means comprises a pair of inclined rails.
44. An apparatus according to any of Claims 30 to 43 comprising a timing means, for example a star wheel, gate, barrier or scroll wheel, between the inclined part and the lead in portion of the movement means.
45. An apparatus according to any preceding Claim, wherein the processing means comprises a computer for running an algorithm for processing the images captured by the camera or cameras and accepting or rejecting the article.
46. An apparatus according to any preceding Claim, comprising a barrier for diverting rejected articles to the accepted and/or rejected position.
47. An apparatus according to Claim 46, wherein the barrier is movable upon a signal from the processing means, to allow an article to pass to the accepted position.
48. An apparatus according to Claim 46, wherein the barrier is movable upon a signal from the processing means, to allow an article to pass to the rejected position.
49. An apparatus according to any of Claims 1 to 45, comprising an ejection means, such as an air rejection device for diverting articles to the accepted and/or rejected position.
50. An apparatus according to any preceding Claim comprising or associated with a manufacturing device for manufacturing articles, preferably preforms for thermoplastic bottles.
51. An apparatus according to Claim 50, wherein the manufacturing device includes a grinding device for grinding rejected articles.
52. An apparatus according to Claim 50 or Claim 51, wherein the manufacturing device is connected to the or an orientation means of the or an inclined part by means of a conveyor, e.g. an elevator conveyor such as a stepped or inclined conveyor.
53. An apparatus according to Claim 51 or Claim 52, wherein the rejected position comprises or is connected to the manufacturing device, such that the materials comprising rejected articles may be reused to manufacture further articles.
54. An apparatus according to any preceding Claim, wherein the path is io substantially linear.
55. A method for inspecting preforms for thermoplastic containers, the method comprising: * continuously conveying articles past a single inspection point; * simultaneously capturing a plurality of images of each article at the inspection point; * examining the images (e.g. automatically examining the images) for defects in each article; * passing articles having no or acceptable defects to an accepted position and passing articles having unacceptable defects to a rejected position.
56. A method according to Claim 55, further comprising capturing an image of a mouth of each preform at the inspection point.
57. A method for inspecting injection moulded preforms for containers, the method comprising: * conveying articles to and/or past an inspection point; * capturing an image of a mouth of each preform at the inspection point; * examining the images (e.g. automatically examining the images) for defects in each article; * passing articles having no or acceptable defects to an accepted position and passing articles having unacceptable defects to a io rejected position.
58. A method according to any of Claims 55 to 57, wherein the preforms each have a gate portion, and wherein at least one of the images captured of each article at the inspection point includes a view of the gate portion.
59. A method according to any of Claims 56 to 58, comprising obtaining a colour measurement of a base of a preform from the image of the mouth of the preform.
60. A method according to any of Claim 55 to 59, wherein the difference in pressure in a region inside the preform to a region immediately outside the preform at the inspection point is substantially zero.
61. An apparatus for inspecting articles substantially as described herein and with reference to the accompanying drawings.
62. A method for inspecting preforms substantially as described herein.