GB2453535A

GB2453535A - Inspecting the sealing of blister packages by detecting the shadow of an anomaly

Info

Publication number: GB2453535A
Application number: GB0719566A
Authority: GB
Inventors: Charles Alban Barker
Original assignee: Sepha Ltd
Current assignee: Sepha Ltd
Priority date: 2007-10-08
Filing date: 2007-10-08
Publication date: 2009-04-15
Also published as: GB0719566D0

Abstract

Inspecting the sealing of a blister package 10 having one or more pockets 12 with a peripheral sealing area 20 around the or each pocket, wherein radiation from a light source 16a, 16b is directed at the peripheral sealing area 20 at an angle of less than 90{ to the peripheral sealing area. Any reduction in reflected radiation due to a shadow of an anomaly is detected by a detector 18 and an image processor determines the acceptability of the blister package based on the pattern of shadowing detected. The anomaly may be a region of weak or faulty sealing or a bubble, ridge, ruck or bump. The radiation may comprise coherent, visible light from a laser.

Description

Method And ADDaratus For Inspect ing The Sealing Of Blister Packages The present invention relates to method and apparatus for inspecting the sealing and integrity of blister packages, in particular for use in detecting anomalies in blister packaging, more particularly, pharmaceutical blister packaging.

Pharmaceutical blister packages have several different construction mechanisms. These fall into three main categories, namely thermoform, coldtorm and occasionally tropicalised packages. The commonest forms are thermoform and coldform, which have two sides; a flat top side and a side with a series of pockets, generally termed the pocket side. More particularly, the pocket side comprises a base layer or tray, usually formed from transparent or translucent sheet plastic material, with an additional aluminium foil layer for a coldform package, the tray having a plurality of recessed pockets formed therein for receiving discrete items to be packaged, such as tablets or capsules of a specific drug, and the flat side comprises an upper layer or lidding foil, usually flat, and usually formed from aluminium foil, bonded to the tray to seal each pocket (by creating "a lid" thereover) and provide an airtight seal around the items being packaged.

Although blister packaging is employed widely throughout the pharmaceutical industry, it is also used in packaging articles in a growing number of other industries. These may include the food industry such as for meat or poultry packaging and the like, beverage and cosmetic industries, medical device industries such as for packaging of sterile syringes or medical tubing, the chemical industry such as for transportation of dry resins, as weH as the automotive, industrial hardware and electronics industries, including packaging IT hardware and software such as microchips.

If the sealing process around a pocket in a blister package is not optimised, or if an anomaly such as a bubble or ridge in the sealed area is present, there is a high probability of leak formation, which can allow ingress of moisture, oxygen or air, which can also contain bacteria.

Research has shown that the ingress of moisture, oxygen or air into packaging can significantly reduce the shelf life of a pharmaceutical drug.

It is therefore necessary to test the integrity of the sealed area around each pocket of the blister package. In the field of pharmaceuticals, it is better to be safe than sorry, i.e. better to reject any potentially unsafe blister packages before sale or use.

In one manufacturing process, a blister pack has pockets which are covered by a flat aluminum foil layer. The aluminium foil around these flat parts is covered by indentations. These indentations are made by a stamp and ensure that the aluminum foil adheres properly to the plastic underneath (to form the seal'). Anomalies such as bubbles or bumps may occur during the indentation process which may indicate that the seal process was not optimal and that there is a possibility of air leaking into a pocket.

Suggestions have been made in the art such as in US 5363968 and US 6757420 for inspecting moving blister packages. The former patent requires capturing a picture of the blister with a high speed camera, and comparing it with nominal characteristics from a test blister, which does not therefore involve an absolute method of analysis of each blister package in its own right. The latter US patent requires lights of different colours and analysis of various wave interference patterns, which requires very accurate placing arrangements to ensure that the interference patterns, based on what should be flat surfaces, are correctly detected.

No prior art suggestions are known to be operable and commercially available.

Current commercial methods for detecting imperfections are based on batch testing. A sample of packages is taken from the production line and subjected to a testing procedure which determines the integrity of the sealing process. Testing techniques include liquid ingress (e.g. a blue or green dye test), ultrasonic testing, or vacuum testing such as described in our US Patent No 6687622. Leakage of gas from minute holes in the packages during evacuation can be detected in gas evacuated from the chambers, and can thereby be used to detect presence of the holes.

Alternatively, pressurizing or partially evacuating the chambers causes gas flow though the minute holes into or from the packages; subsequent abrupt return of the chambers to initial pressure causes momentary distortion of flexible wall layers of the packages which is indicative of the presence of the minute holes. Such distortion can be determined by, for example, visual inspection or profile interrogation using laser beams.

Such apparatus can provide very accurate diagnostic ability, but not with any speed. Indeed, all of these techniques are useful for off-line testing but are not fast enough to offer the prospect of 100% on-line inspection.

The present invention provides novel improvements over existing techniques because it is able to implement anomaly detection to determine weak seals at a sufficiently inexpensive and fast rate to be applied to on-line or continuous blister package inspection, offering the opportunity to implement testing of all blister packages, rather than batch testing of only some.

Thus, the present invention is able to test all blister packages at the rate of blister package mass-production, requiring no slowdown or reduction in blister packaging manufacture whilst still providing testing of all packages formed.

Another object of the present invention is to provide very accurate anomaly locational information.

It is a further object of the present invention to provide a non-destructive test, that is a method and apparatus for inspecting the sealing and integrity of blister packages that does not affect the packages, their seals, or their contents. This is extremely beneficial in the field of pharmaceuticals, where pharmaceuticals from any failing or rejected blister packages can be extracted for re-packaging, and/or blister packages which pass or succeed the testing are still in a form which is acceptable for sale and use under the various pharmaceutical regulations.

Thus, according to the first aspect of the present invention, there is provided a method for inspecting the sealing of a blister package, the blister package having one or more pockets and a peripheral sealing area around the or each pocket, the method at least comprising the steps of: I) directing radiation at one or more peripheral sealing areas of the blister package at an angle of incidence of between 00 and <900 to the peripheral sealing area(s); and ii) detecting any reduction of the reflected radiation intensity due to a shadow of an anomaly in at least one of the peripheral sealing areas.

Thus, radiation directed at an angle, preferably a low angle, towards a peripheral sealing area of the blister package results in a shadow being formed across the sealing area if there is any anomaly present. This results in a reduction in the amount of reflected radiation being transmitted from the peripheral sealing area of such a blister package compared with the amount of reflected radiation transmitted from a defect-free sealed area of a blister package. The transmitted radiation can then be analysed to provide locational information as to the approximate or exact position and size of said anomaly.

Such information can be used to consider where any fault or flaw in the process for sealing the blister package is or has occurred. For instance, the re-occurring detection of a region of weak or faulty sealing indicated by a bump or bubble in the same position on a number of blister packages could indicate that there may be a specific fault with the sealing process, for example, where forming rollers have become worn and are providing insufficient sealing pressure.

Typically, the anomaly is a region of weak or faulty sealing. More typically, the anomaly is one or more of the group comprising: a bubble, a ridge, a ruck and a bump. Indeed, any unintended difference in height of part of a peripheral sealing area will create a shadow.

A peripheral sealing area is the sealing area around the or each pocket of the blister packaging, preferably to make an airtight or hermitic seal.

The peripheral sealing area may be interlinked or co-joined with the peripheral sealing area of an adjacent pocket to create a pocket to pocket seal. Additionally or alternatively, the peripheral sealing area may extend from the pocket to any edge of the blister package creating a pocket to edge seal.

The angle of incidence may be between >00 and 450, preferably between >00 to 200 to the peripheral sealing area.

The step of directing radiation onto a peripheral sealing area of the blister package may be carried out across only a portion of the peripheral sealing area around the or each pocket of the blister package.

Preferably, the step of directing radiation onto the peripheral sealing area of the blister package is carried out across the whole surface of the peripheral sealing area of each pocket.

The radiation may comprise visible light or may comprise at least one beam of coherent light from a laser.

In one embodiment the radiation is provided by a focused beam, and comprises an optical light source, more preferably a laser.

Preferably, the blister package is illuminated with an even intensity of radiation.

Preferably, the method further comprises processing the reflected radiation by an image processor to determine the pattern and position of shadowing across at least a portion of the peripheral sealing area of the blister package.

Preferably, the image processor determines the position of the anomaly.

In one embodiment, the radiation is directed towards the or each peripheral sealing area from two or more directions. This can be performed by two separate light sources or alternatively by one light source wherein the light source is movable from one direction to another.

In another embodiment, an image processor is able to process the reflected radiation from a plurality of directions towards a single anomaly on the peripheral sealing area, at a range of angles. The image processor then processes each set of shadowing information obtained from reflected light intensities from any direction for each anomaly, and collates each data set to provide an accrued assessment of the location and nature of the anomaly or anomalies on the peripheral sealing area of the blister package.

Advantageously, the decrease in the intensity of radiation reflected from a peripheral sealing of the blister package as a result of the presence of an anomaly on the peripheral sealing area provides a measure of the size and height of the anomaly, and thus a measure of the damage to the seal of the blister package.

One manner of analysing the intensity of radiation detected is to determine the intensity of radiation received at a number of different threshold levels, and/or in a number of predetermined areas.

Computation of such information can provide a map' of the inspected surface, and an indication of those areas of the surface which pass or fail any predetermined or threshold values set. Such information can determine edge-to-pocket sealing as well as pocket-to-pocket sealing information. Some areas of the surface may be insufficient, but if such areas do not extend to the edge of a pocket and/or the edge of the blister package, it may in fact allow the blister package still to be considered to pass the determination of a good seal.

In another embodiment, the blister package is moving, and is being conveyed whilst undergoing the method of the present invention. This can be applied in an on-line or Continuous blister package inspection.

Alternatively, the blister package is wholly or substantially stationary having being conveyed to a location for undergoing the method of the present invention, and then is conveyed therefrom thereafter.

Preferably, the method of the present invention involves detecting an imperfection in a plurality of moving or conveyed blister packages, optionally at high speed.

Preferably the method of the present invention includes the further step of determining the acceptability of the blister package based on what is detected, for instance the sealing of the blister package based upon the detected reduction in intensity due to shadowing by the anomaly. Such acceptability determination may be in the manner of a decision as to whether the package being inspected meets or fails to meet a particular quality requirement or may determine the quality of the seal as falling into one of a range of levels of quality, some being rejected, some accepted and other being identified as requiring further checking, e.g. by a static batch' testing apparatus.

A second aspect of the invention provides an apparatus for inspecting the sealing of a blister package, the blister package having one or more pockets and a peripheral sealing area around the or each pocket, comprising: i) at least one laser for directing radiation at one or more of the peripheral sealing areas of the blister package at an angle of incidence of between 00 and <900 to the peripheral sealing area(s); ii) a detector for detecting any reduction of the reflected radiation intensity due to a shadow of an anomaly on at least one of the peripheral sealing areas of the blister package; and iii) an image processor for determining the pattern of shadowing detected, wherein the pattern of shadowing determines the acceptability of the blister package.

Optionally, the laser is deflected through a beam scanner or mirror for faster scanning, the beam of light from the light source across the peripheral sealing area of the blister package in a direction transverse to the direction of any movement of the blister package through the apparatus.

In one embodiment, the image processor processes the reflected radiation from a plurality of directions towards a single anomaly on the peripheral sealing area, at a range of angles, preferably low angles. The processing of collated shadowing information obtained from each direction allows for a rapid and accurate assessment of the position of the anomaly on the sealing area by the processor.

Preferably, the detector for detecting the radiation, preferably for measuring the intensity of radiation emitted from the surface of the blister package, comprises one or more photo-detectors, preferably located wholly or substantially in alignment with the edge or edges of the blister package.

In a preferred embodiment the detector is arranged to detect the intensity of radiation reflected in a direction substantially normal to the peripheral sealing area of the blister package.

Preferably the image processor determines the position of the anomaly.

Preferably, an image processor is provided for processing the reflected radiation intensity measured across at least a portion of the peripheral sealing area of the blister package which is recorded by the detector.

Said image processor may compare said pattern of reflected radiation with a standard or quality control reference, e.g. that expected of a well-sealed package, or with other calibration data to determine the presence and location of overall and/or localised regions of bubbles or other anomalies. The image processor may comprise a camera connected to a computing device.

The camera may be a charged coupled device (CCD) camera, or another type of camera.

Preferably the blister packages are conveyed through the apparatus, and conveying and/or guide means are provided for conveying and/or guiding the blister packages through the apparatus.

The apparatus may include means to reduce and/or exclude the radiation, e.g. light, other than from the radiation source, being present around the blister package under investigation, and/or the radiation being detected by the detector(s). Such means includes one or more light barriers, shrouds, rollers, curtains, etc. or the like. Such means may be movable with the blister package, and/or rnoveable relative thereto, or static.

Preferably the apparatus of the present invention further comprises means for determining the acceptability of the blister package based on what is detected, e.g. the sealing of the blister package based upon the detected reduction of intensity of the reflected radiation.

For example, the image processor may apply a reject criteria when determining the acceptability. The reject criteria may be based on the magnitude of the reduction in intensity indicating one or more anomalies.

The processor may analyse the intensity of radiation to detect any shadows of anomalies of greater than a pre-determined dimension and/or greater than a pre-determined reduction in intensity, and if any are found, the packaged product may be rejected.

By "peripheral sealing area" of a blister package having at least a pocket is meant any peripheral sealing area surrounding each pocket to seal, preferably hermitically seal, each pocket and provide an airtight seal around the items being packaged within each pocket. The peripheral sealing area may provide a pocket to pocket seal or a pocket to edge seal.

In one example, a blister package comprises two sides; a flat top side, and a side with a plurality of recessed pockets, commonly termed the pocket side. Generally, a blister package may be of any dimension or configuration such that a portion of the blister package which may be the pocket is capable of holding an item of any size or shape, to be sealed.

The blister package may have one or more sides or surfaces wherein at least a portion of the surface is a peripheral sealing area. Such blister packages may be of any shape including but not limited to spherical, triangular, square, rectangular, or having a plurality of sides such as a pentagon. Many pharmaceutical blister packages are regarded as being flat', and this having two sides. Those persons skilled in the art will appreciate the types of blister packaging arrangements that exist.

Blister packages which are able to be inspected by the apparatus and method of the present invention may be of any suitable size, shape or design, and may be able to contain any suitable items which it is desired to protect in one way or another between their point of manufacture and point of sale. Typically blister packages are for pharmaceuticals, commonly but not exclusively in a solid form such as tablets or capsules, as well as products used in the medical device or healthcare industries for example contact lenses, sterile syringes or medical tubing for use in haemodialysis. The present invention also extends to blister packaging in the electronics industry such as for packaging of microchips or the like or small electrical circuit items or pieces including other IT hardware or software pieces, food and beverage packaging such as for meat or poultry. Blister packaging may be required for items used in wide variety of other industries such as cosmetic, chemical, automotive and industrial hardware. The person skilled in the art will be aware of other items suitable for blister packaging.

Such packaging may be for health and safety concerns, and/or may be to assist compartmental isation of suitable items either to assist in manufacture, sale or use. It will also be noted that a blister pocket may contain more than one item, or that different pockets may contain different items. Generally, but not exclusively, all pockets of a blister package contain the same item. Also commonly, but not exclusively, all blister packages formed in a batch' contain the same or related items. A batch' is generally any group of blister packages made under the same conditions and with the same materials and for the same enclosed item.

The method and apparatus of the present invention includes the ability to be adapted to accommodate blister packages of different size, shape and design. This may require some adjustment of physical and/or radiation parameters, but such is within the skill of the person skilled in the art, The present invention is not limited by the size, shape and dimensions of the blister packet, or the items within the blister pocket.

Scanning for anomalies using the detection method and apparatus of the present invention provides a means of providing very accurate locational information as to the position and size of the anomaly, the benefit and consequence of which is discussed hereinbefore. Moreover, scanning provides an ability to scan across the peripheral sealing area of a blister package to detect shadowing, resultant from anomalies such as bubbles or ridges, and also ensures that the blister package is illuminated with an even intensity.

The term "continuous" and/or "on-line" as used herein relates to the ability of the present invention to inspect moving blister packages, and blister packages at the rate at which they are formed, filled and sealed.

This is in contrast with batch testing' which is static testing of a sample of blister packaged formed. Batch testing of all blister packages could of course be carried out, but the loading and unloading of blister packages from batch testing apparatus make this un-economical. The continuous or on-line inspecting of blister packages by the present invention may still involve one or more times when a blister packet is stationary, or may be intermittent due to the intermittent manufacture of blister packages, but it is still intended that all blister packages formed, filled and sealed undergo the inspection of the present invention prior to distribution, sale, use, etc. Conveying apparatus used in continuous inspection are well known in the art, and can include the use of a conveyer belt and/or series of rollers able to convey a blister package from a place of entry to the apparatus, such as the feeding tray or magazine, and a place of exit from the apparatus and/or place of acceptance or rejection of the blister package after having been inspected. Such conveying apparatus may include one or more guide means, again including rollers and the like, which are well known in the art.

The apparatus of the present invention may be connected directly or indirectly to a blister package production line, such that once the blister package is formed, filled and sealed, it is passed wholly or substantially directly through the apparatus of the present invention. The movement of the blister packages provides the "continuous" or "on-line" ability of the present invention over hitherto static' batch testing.

The present invention is also able to be carried out at atmospheric conditions, that is it does not require any increase or decrease in pressure on or around the blister packages. This significantly reduces the complexity of the invention compared with many prior art devices, which require some form of increase or decrease in pressure, in particular applied vacuum. The present invention can therefore be easily applied in connection with general blister package manufacturing processes.

The present invention preferably includes a method and apparatus to indicate and/or cause the acceptance or rejection of a blister package either during or after its inspection. This could include one or more decision stations and/or one or more gates, adapted to act upon the information provided by the method of inspection. The present invention could also therefore include one or more locations or areas considered to receive or accept blister packages which pass or succeed the method of inspection, and one or more areas adapted to accept or receive blister packages which are considered to fail or be rejected by the method of inspection.

The present invention could also be adapted to make a decision on the acceptance or passing of a blister pack by the method of inspection, or its rejection or failure, either manually and/or automatically. Such ability may include action concerning one or more blister packages following any rejected or failed blister package, e.g. the next five blister packages just in case there could be a continuing fault in the manufacturing process, as well as ability to stop the inspection, for example to allow manual inspection or further and/or re-testing of the blister package.

In the present invention, blister packages may be inspected in a step wise or indexed manner. Preferably, they are inspected in a continuous manner, and are supplied in a Continuous form. Blister packages may be supplied by any suitable feeding mechanism known in the art, preferably one at a time.

The present invention may include one or more channels through which a blister package may pass for inspection. Such channels may equate to one or more apparatus for each test acting in series or parallels. One or more of each apparatus may be adapted to work with the same or different number of other apparatus. In one embodiment, apparatus for detecting imperfections such as bubbles in a blister package can operate at a rate sufficient to supply a number, such as 2-4, apparatus for detecting anomalies such as bubbles or bumps.

Preferred features of each aspect of the invention are as for each of the other aspect mutatis mutandis.

Embodiments of the invention will now be described, by way of example only, with reference to the diagrammatic drawings, in which: Figure 1 is a front view of a blister package and a method of inspecting the sealing of the blister package according to an embodiment of the present invention; Figure 2 is a perspective part view of the blister package and the anomaly detecting apparatus of Figure 1; and Figure 3 shows a top view of "shadowing" across the peripheral sealing area of a blister package surface having an anomaly in a localised region.

Referring to the drawings, Figure 1 shows a blister package 10 having a number of pockets 12, around which is a peripheral sealing area 20 which extends across the entire top surface of the blister package 12 (except where the pockets 12 exist).

Figure 1 also shows two light sources 16a and 16b, and a camera 18.

When each light source 1 6a, 1 6b is directed at a different angle at the peripheral sealing area 20 of the blister package 12 at a low angle, preferably between >00 to 20° to the plane of the blister package 12, then any anomaly such as a bubble 14 present on the peripheral sealing area 20, casts a shadow 22a and 22b along the surface of the blister package 12. In figure 1, the first light source 16a wilt create a first shadow 22a, and the second light source 16b will create a second shadow 22b.

Because of the shadows 22a, 22b, the level of light being reflected and transmitted from the peripheral sealing area 20 of the blister package 12 to the camera 18 from each light source 1 6a, 1 6b, will be reduced. The use of low angle illumination is designed to enhance the shadowing effect created by the bubble 14 on the sealing 20 of the blister package 12. The actual level of reflected light can be processed by an image processor (not shown), which can then localise the position of the bubble 14 based on positional information about the blister package 12.

Figure 2 is a perspective part view of Figure 1. For the sake of clarity, Figure 2 shows just the first light source 16a directing light onto the bubble 14 on the peripheral sealing area 20 of the blister package 12 at a low angle, thus creating a shadow 22a along the peripheral sealing area of the blister package 12.

Should space considerations dictate otherwise, it is envisaged that the camera 18 may be orientated in a direction other than perpendicular to the peripheral sealing area 20 of the blister package 12 without compromising the ability of the present invention to detect faulty blister packages. However, it is preferred that the camera 18 be arranged at an angle of no more than 300 from the vertical.

The reduction of intensity of the light reflected from the peripheral sealing surface of the blister package provides a measure of the number, height and size of the bubble.

Figure 3 shows a top view of the blister package 12, and the shadowing 22a on an illuminated image 24 of the surface of a blister package 12 resulting from the bubble 14 shown in Figures 1 and 2, as viewed by the camera 18.

The seal inspection of Figures 1 and 2 could also be integrated into the blister package production process, and be provided with conveying devices or other handling means for intercepting blister packages that are determined as having sealing faults. Such rejected blister packages may subsequently be subject to traditional batch leak inspection processes if desired.

Whilst the preferred embodiment specifically relates to an apparatus and method for the inspection of a pharmaceutical blister package, the invention is equally applicable to any product packaged in blister packages of any shape or size.

It will be appreciated that modifications can be made to embodiments of the invention described in the foregoing without departing from the scope of the invention.

Claims

Claims 1. A method for inspecting the sealing of a blister package, the blister package having one or more pockets, and a peripheral sealing area around the or each pocket, the method at least comprising the steps of: i) directing radiation at one or more of the peripheral sealing areas of the blister package at an angle of incidence of between 00 and <900 to the peripheral sealing area(s); and ii) detecting any reduction of the reflected radiation intensity due to a shadow of an anomaly in at least one of the peripheral sealing areas.
2. A method as claimed in Claim 1 wherein radiation is directed onto the peripheral sealing area(s) from two or more directions.
3. A method as claimed in Claim 1 or Claim 2 wherein the anomaly is a region of weak or faulty sealing.
4. A method as claimed in any one of Claims 1 to 3 wherein the anomaly is one or more of the group comprising: a bubble, a ridge, a ruck and a bump.
5. A method as claimed in any one of the preceding claims wherein the angle of incidence is between >00 and 45°, preferably between >0° to 20° to the peripheral sealing area.
6. A method as claimed in any one of the preceding claims, wherein the step of directing radiation onto a peripheral sealing area of the blister package is carried out across only a portion of the peripheral sealing area around the or each pocket of the blister package.
7. A method as claimed in any one of the preceding claims, wherein the radiation comprises visible light.
8. A method as claimed in claim 7, wherein the radiation comprises at least one beam of coherent light from a laser.
9. A method as claimed in any of the preceding claims, wherein the method further comprises processing the reflected radiation by an image processor to provide for determining the pattern of shadowing across at least a portion the peripheral sealing area of the blister package.
10. A method as claimed in any one of Claims 2 to 9, wherein the method further comprises processing the reflected radiation from two or more directions by an image processor, and collating each set of data obtained for each direction to determine the pattern of shadowing across at least a portion the peripheral sealing area of the blister package.
11. A method as claimed in Claim 9 or Claim 10, wherein said image processor determines the position of the anomaly.
12. A method as claimed in any one of the preceding claims wherein the method includes the further step of determining the acceptability of the blister package based upon the intensity of the reflected radiation.
13. A method as claimed in any one of the preceding claims wherein the method is a continuous or on-line method of inspection.

14 An apparatus for inspecting the sealing of a blister package, the blister package having one or more pockets and a peripheral sealing area around the or each pocket, comprising: i) at least one laser for directing radiation at one or more of the peripheral sealing areas of the blister package at an angle of incidence of between 00 and <900 to the peripheral sealing area(s); ii) a detector for detecting any reduction of the reflected radiation intensity due to a shadow of an anomaly on at least one of the peripheral sealing areas of the blister package; and iii) an image processor for determining the pattern of shadowing detected, wherein the pattern of shadowing determines the acceptability of the blister package.