07.12.23
The inspection of variable data, such as matrix codes, barcodes or alphanumeric strings, differs fundamentally from conventional print inspection because the print image changes during the inspection job. A master image comparison is not possible in this case. Examples of common applications include pharmaceutical industry batch numbers and profit codes in marketing activities.
To drive success in this arena, BST TubeScan digital strobe checks variable character strings and barcodes inline, decodes and evaluates them simultaneously. The system uses smart BST image processing in combination with high-resolution matrix cameras to check the correctness and functionality of the printed products.
Since 2021, the French label printing specialist, Lorge Imprimeur, has been successfully using the system to verify labels with variable barcodes produced in digital printing and compare their content with a database provided.
Lorge produces small and large batches of self-adhesive labels on rolls using digital and flexographic printing. The manufacturer required a system that would simultaneously check the printed image of the labels and validate the variable data printed on them. The company installed a BST TubeScan digital strobe 430 with a high-resolution 4K camera on a converting machine. In the event of both print errors and code data errors, the machine automatically stops to take appropriate corrective action. The read codes with inspection results are stored in a results database on an order-by-order basis.
BST TubeScan reads the content of the codes, verifies the decoded information for continuous sequence, unintentional repetition or against an input database, and optionally checks the print quality inline according to ANSI/ISO classification. The system closes a crucial gap between the quality demands of customers and economic feasibility. Brand owners often require their products to meet the minimum quality of C on the ANSI scale from A to F. The system is also able to check the print quality inline.
The barcode module of BST TubeScan provides an attractive solution for this. It is based on the ISO/IEC 15426-1 and ISO/IEC 15426-2 standards for barcode inspection devices, which examine quality criteria such as symbol contrast, bar width variation, or raster non-uniformity and, when combined with offline verification, provide 100% inline quality control. The minimum resolvable module size, i.e. the smallest element of a code, depends on the resolution of the selected camera configuration. A matrix code's element must be at least three pixels wide, while a barcode's smallest bar width must be at least two pixels wide.
Parallel to the inspection of the printed image, TubeScan performs an inline and real-time comparison of the inspected code with the input database. TubeScan saves the comparison results with other inspection results into a CSV file. This is also true at Lorge in France, where TubeScan has been integrated into the company's network. The system reads the CSV file assigned to the job from the server at the beginning of the roll processing and stores the result file in a new folder there after the inspection is complete.
To set up the inspection job, TubeScan captures a reference image at the beginning of the roll. The operator specifies the barcode zones to be inspected. After the reference image is taken, the machine requires additional time for image stabilization and illumination adjustment. No inspection-relevant data can yet be positioned on the web in order to set up these processes reliably. As a result, a blind code typically runs in this setup section. This is exactly how Lorge did it: the label specialist used several meters of identical blind codes for the setup in advance. TubeScan recognizes the blind codes and reliably distinguishes them from the relevant codes, allowing the start of inspection to be precisely triggered. This procedure ensures that all relevant codes in the roll are inspected and recorded into the database. At the same time, the setup area can be easily marked or removed for the end customer.
Variable data defects in the QLink workflow
If the variable data was previously inspected on the press, the inspection results can easily be integrated into the QLink workflow: Defects are stored in a roll protocol, just as print image inspection. This protocol, which enables defects to be placed precisely and processed, can be loaded for further processing on a rewinder equipped with TubeScan. The defect image is conveniently displayed on the TubeScan monitor to facilitate the detection of the defective code.
Whether it's forgery-proof winning codes for a marketing campaign, legally standardized batch numbers or machine-readable medication labels in the pharmaceutical industry, the coding must be clearly legible and valid in each case. OCR (Optical Character Recognition) is the supreme discipline in reading variable data. It is characterized by the uniqueness of a continuous sequence of serial numbers. A slight stroke turns a 7 into a Z, or a printhead misalignment can cause two Vs to merge into a W. This is especially important for products where the print quality is lower because the coding has been applied subsequently with an inkjet printer. Even in this case, TubeScan will achieve nearly a 100% success rate if the print design meets certain quality criteria.
The fewer different character types utilized, the more robust the recognition: Codes consisting exclusively of digits can be read best, as can capital letters. The danger of error increases when both sorts of characters are used with lowercase letters. For a TubeScan with 0.083 mm resolution, the font height should be at least 30 pixels, which translates to a font size of 7 points. Sufficient spacing is crucial so that the software can distinguish the characters from each other. It is recommended to preserve the default size and avoid using compressed fonts. When possible, OCR fonts should be used. Although Arial can be used, there is a potential of misinterpretation with the letters and 'I' and 'l'.
To drive success in this arena, BST TubeScan digital strobe checks variable character strings and barcodes inline, decodes and evaluates them simultaneously. The system uses smart BST image processing in combination with high-resolution matrix cameras to check the correctness and functionality of the printed products.
Since 2021, the French label printing specialist, Lorge Imprimeur, has been successfully using the system to verify labels with variable barcodes produced in digital printing and compare their content with a database provided.
Lorge produces small and large batches of self-adhesive labels on rolls using digital and flexographic printing. The manufacturer required a system that would simultaneously check the printed image of the labels and validate the variable data printed on them. The company installed a BST TubeScan digital strobe 430 with a high-resolution 4K camera on a converting machine. In the event of both print errors and code data errors, the machine automatically stops to take appropriate corrective action. The read codes with inspection results are stored in a results database on an order-by-order basis.
BST TubeScan reads the content of the codes, verifies the decoded information for continuous sequence, unintentional repetition or against an input database, and optionally checks the print quality inline according to ANSI/ISO classification. The system closes a crucial gap between the quality demands of customers and economic feasibility. Brand owners often require their products to meet the minimum quality of C on the ANSI scale from A to F. The system is also able to check the print quality inline.
The barcode module of BST TubeScan provides an attractive solution for this. It is based on the ISO/IEC 15426-1 and ISO/IEC 15426-2 standards for barcode inspection devices, which examine quality criteria such as symbol contrast, bar width variation, or raster non-uniformity and, when combined with offline verification, provide 100% inline quality control. The minimum resolvable module size, i.e. the smallest element of a code, depends on the resolution of the selected camera configuration. A matrix code's element must be at least three pixels wide, while a barcode's smallest bar width must be at least two pixels wide.
Parallel to the inspection of the printed image, TubeScan performs an inline and real-time comparison of the inspected code with the input database. TubeScan saves the comparison results with other inspection results into a CSV file. This is also true at Lorge in France, where TubeScan has been integrated into the company's network. The system reads the CSV file assigned to the job from the server at the beginning of the roll processing and stores the result file in a new folder there after the inspection is complete.
To set up the inspection job, TubeScan captures a reference image at the beginning of the roll. The operator specifies the barcode zones to be inspected. After the reference image is taken, the machine requires additional time for image stabilization and illumination adjustment. No inspection-relevant data can yet be positioned on the web in order to set up these processes reliably. As a result, a blind code typically runs in this setup section. This is exactly how Lorge did it: the label specialist used several meters of identical blind codes for the setup in advance. TubeScan recognizes the blind codes and reliably distinguishes them from the relevant codes, allowing the start of inspection to be precisely triggered. This procedure ensures that all relevant codes in the roll are inspected and recorded into the database. At the same time, the setup area can be easily marked or removed for the end customer.
Variable data defects in the QLink workflow
If the variable data was previously inspected on the press, the inspection results can easily be integrated into the QLink workflow: Defects are stored in a roll protocol, just as print image inspection. This protocol, which enables defects to be placed precisely and processed, can be loaded for further processing on a rewinder equipped with TubeScan. The defect image is conveniently displayed on the TubeScan monitor to facilitate the detection of the defective code.
Whether it's forgery-proof winning codes for a marketing campaign, legally standardized batch numbers or machine-readable medication labels in the pharmaceutical industry, the coding must be clearly legible and valid in each case. OCR (Optical Character Recognition) is the supreme discipline in reading variable data. It is characterized by the uniqueness of a continuous sequence of serial numbers. A slight stroke turns a 7 into a Z, or a printhead misalignment can cause two Vs to merge into a W. This is especially important for products where the print quality is lower because the coding has been applied subsequently with an inkjet printer. Even in this case, TubeScan will achieve nearly a 100% success rate if the print design meets certain quality criteria.
The fewer different character types utilized, the more robust the recognition: Codes consisting exclusively of digits can be read best, as can capital letters. The danger of error increases when both sorts of characters are used with lowercase letters. For a TubeScan with 0.083 mm resolution, the font height should be at least 30 pixels, which translates to a font size of 7 points. Sufficient spacing is crucial so that the software can distinguish the characters from each other. It is recommended to preserve the default size and avoid using compressed fonts. When possible, OCR fonts should be used. Although Arial can be used, there is a potential of misinterpretation with the letters and 'I' and 'l'.