The increasing use of machine-readable codes rather than human-readable ones in the pharmaceutical and medical technology industries has significantly increased the use of industrial vision in these important sectors. In the pharmaceutical industry, it is essential that the correct product ends up in the correct container, with the correct label applied and the correct usage instructions included in the packaging.
From a safety point of view, errors could have potentially fatal consequences for the end-user with extreme repercussions for the manufacturer. However, there is also an increasing focus on eliminating the production of counterfeit medicines. One approach is serialisation where the product is marked with unique data rather than having unique packaging so there is no need to use counterfeit-proof packaging and markings, such as holograms. The European Union has announced that it will implement the ‘Falsified Medicines directive (2011/62/EU) in 2014. This new act is intended to ensure that medicines are safe and that the trade in medicines is rigorously controlled.
Part of this directive will include the use of obligatory ‘safety features’ to allow, inter alia, verification of the authenticity of medicinal products (a ‘unique identifier’).
Eliminating human error
Typical data that needs to be checked on labels and packaging includes, product names, drug names, dosages, batch numbers, ‘best before’ or expiry dates and apart from any mismatches, labels can be rejected if they are only partially printed, or if the print is smudged for example. Vision systems allow these processes to be automated and carried out at production line speeds, without being subject to the distractions, lack of concentration and tiredness experienced by human inspectors. Because vision systems can operate at production line speeds they open up the possibility for 100 per cent inspection rather than inspection based on sampling that occurs when using human inspectors. Vision technology can also cope with coded information in the form of barcodes or 2D datamatrix codes as well as human readable codes. This is important in applications where machine readable code sits alongside human readable code. In the UK and Ireland, the 13 digit GS1 GTIN 1D code structure is used and there is another barcode standard Pharmaceutical Binary Code (Pharmacode) used in packing control systems. It is designed to be readable despite printing errors with the number encoded in binary rather than human-readable decimal digits.
The sheer variety in coding types and labelling methods places high demands on industrial vision systems. In the first instance, they need to be capable of carrying out the vision task required, but also they need to be seamlessly integrated into the production process, complete with an appropriate reject mechanism. The complexity of the vision solution required for 1D barcodes, 2D datamatrix codes, date codes, lot codes, serial numbers and other text based codes depends on a number of factors.
These include regularity of the code or label orientation on the product or package; position of the code on the product; regularity of the codes or characters (eg are the characters stretched or skewed?); is there damage to the code?; the contrast between the code or characters and the background; the code/background colour combinations; reflections from surrounding surfaces; the space available for the vision system; speed of measurement; connectivity around the production facility and integration into the production control system.
A process called verification is used to measure and grade the quality of a printed 1D or 2D code in its final configuration. Verifying that a code has been printed accurately is very different from reading the code itself. Any vision system used to check the quality of GS1 barcodes should conform to the international standard ISO/IEC 15426-1, which will ensure that the codes are graded according to the standard ISO/IEC 15416, while 2D codes are frequently verified according to the parameters of ISO/IEC 15415.
Solving the problem
Although stand-alone code and label reading vision systems are available, custom-designed systems are often the preferred and pharmaceutical manufacturers frequently turn to specialised vision systems integrators, such as Olmec-UK to both solve the particular vision problem and handle the integration into the process.