Braille is enormously important for people with visual impairments, especially when identifying medicines. With the DotScan inspection system based on industrial cameras and lenses from SVS-Vistek, in-situ ensures error-free Braille on pharmaceutical packaging.

Even a single missing Braille dot can change the message of a Braille text. Such mistakes in the identification of medicines are particularly consequential when an actual active ingredient quantity “500 mg” can be incorrectly identified as “100 mg” for the visually impaired, thus posing the risk of a severe overdose.

In order to minimize such risks, the Sauerlach-based system house for image processing in-situ has developed the Braille inspection system DotScan. “This robust system enables a reliable inspection of Braille on pharmaceutical packaging and embossing dies,” says in-situ Managing Director Sandra Söll, describing the basic function of DotScan. “Not only the presence of the Braille dots and the correct combination of dot patterns are checked, but also the correct height of the Braille dots according to DIN EN ISO 17351.”

According to Söll, there are basically two ways of embossing Braille dots: either when punching complete printed sheets or in a later process step using rotary embossing tools during further processing of the boxes in a glueing machine. “Our DotScan systems are designed to check Braille on empty, unfolded folding boxes offline during the production process. It is important that the inspection is carried out on the printed side. This is how we ensure that the front is correct, where the visually impaired feel the Braille indications.” In many cases, the Braille dots are also embossed in areas of a box that are printed with graphics or text. Busy backgrounds of this type make correct recognition by a vision system more difficult.

 

Image processing optimised

In order to be prepared for such demanding conditions, in-situ now relies on image processing components from SVS-Vistek. “Cameras from another manufacturer were integrated in the first generation of our DotScan systems, but they no longer met our increased requirements,” explains Söll. “Among other things, we wanted to optimize the image processing setup in terms of hardware and found the camera concept of the EXO series from SVS-Vistek very convincing. The ability to control lighting directly in the camera eliminates the need for the otherwise common flash controllers, saving hardware costs as well as time during integration.”

The illumination control integrated in the SVS-Vistek cameras simplifies the in-situ preferred method of capturing multiple images under different lighting conditions and directions in order to calculate pseudo-3D images from the image data generated in this way. The company has already achieved very good results with this shape-from-shading method in many of its installations. Among other things, it has the great advantage that height values can be determined largely independently of the imprint.

In addition, the selected EXO models offer the option of storing certain information in the cameras. In this way, system integrators of machine vision systems can protect their know-how against unwanted duplication via a customer ID, for example. “The camera then acts as a hardware dongle that requires a customer-specific password,” explains Christian Schaarschmidt from SVS-Vistek, who provides in-situ with sales support and has intensively accompanied the development of the new DotScan generation in terms of the cameras and optics used.

For Söll and her development team, another argument for switching to cameras from the EXO series was that important information such as metric calibration data can be stored in non-volatile RAM memory in the camera and protected via a customer ID. To accomplish this, SVS-Vistek programs the cameras with customer-specific firmware and deliveres them to their customers already fully configured. “In this way, integrators can retrieve such data at any time. In addition, an external device is no longer required for storing configuration data, which reduces the complexity of the in-situ devices and enables faster setup by the end user,” emphasizes Schaarschmidt.

 

Height tolerance 0.02 mm

The high bit depth of 12 bits as well as the easily sufficient resolution of the selected EXO camera models for this application were further reasons for in-situ to trust SVS-Vistek as supplier for the cameras and optics in the DotScan systems, especially since the technically optimal lenses for the small sensor pixels of these cameras could also be obtained directly from SVS-Vistek. In addition to the purely technical features of the cameras, another important issue is decisive for the satisfaction regarding the cooperation with SVS-Vistek, according to Söll: “Even in the recently very tense delivery situation in many areas, we have reliably received the required cameras and lenses from SVS -Vistek and were therefore able to meet the schedules for our customers. This is currently not a matter of course and has shown us that we have chosen the right supplier.”

With the selected image processing setup and the shape-from-shading technology implemented with it, the DotScan systems are able to verify the embossed Braille labels with extreme accuracy and reliability at speeds of less than 1.5 seconds per pack, in-situ Managing Director Söll is pleased to report. “With a height verification tolerance of just ± 0.02 mm, DotScan absolutely reliably detects existing errors by comparing them to a reference dot arrangement, thereby helping to ensure that visually impaired people can also safely take the correct medication.”

According to the current status, German pharmaceutical companies and global packaging groups use around 200 DotScan systems to check Braille writing in more than 30 Braille languages on medicine packaging. It looks very likely that the new generation systems equipped with SVS-Vistek’s EXO cameras will increase this number even further.

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