Optical Inspection of Pharmaceutical Labels

Artur Theis GmbH & Co. KG of Wuppertal, Germany has decades of expertise in the field of manufacturing folding cartons for pharmaceutical products. With one of its latest machines, the company affixes the high-quality packaging with different identification and information carriers. These include labels with one-dimensional codes, genuine lettering and holograms, as well as bollinos (Italian for “coupon” or “trading stamp,”), which are pharmaceutical stickers that can be partially or completely removed from the packaging.

The new machine can affix labels, stickers, and bollinos to up to 200 different types of folding cartons and check that they are in the correct position. To ensure that every sticker is accurately in place, Artur Theis uses an intelligent vision system with integrated pattern matching technology to check the positioning.

Zertrox GmbH & Co. KG of Aachen implemented the image-based testing station for the machine. Zertrox specializes in measurement and control technologies. The company is a systems integrator working with Cognex, maker of the vision system, to assist companies in the design, development and operation of PC-based measuring and image processing systems and laser controls.

Better than the Human Eye
In the past, Artur Theis performed the inspection of product characteristics with the human eye. However, the increased level of automation in the pharmaceutical industry made it much more difficult to inspect packages for important information and data carriers.

In addition, affixing additional information on the packaging requires far greater precision than the human eye can provide. Pharmaceutical manufacturer routinely need to include the use-by date, product and lot numbers, as well as information for healthcare providers such as health insurance funds. If the labels and stickers are not perfectly aligned to the central features of the folding cartons, then the additional information cannot be applied correctly.

The Cognex In-Sight Micro 1400 intelligent vision system with PatMax pattern matching technology is integrated into the new Artur Theis machine to check the exact positioning of the labels. The In-Sight Micro 1400 provides extremely high repeat inspection accuracy within specified tolerances, and identifies possible defective products so they can be reliably removed.

One of the biggest challenges in this process was the identification of the labels at extremely high volumes—up to 40,000 cartons per hour. Only the In-Sight Micro 1400 with PatMax was able to do the job at the speeds needed.

Due to the large variety of products with very different label shapes and colors, it could not be assumed during the system design that all of the boxes would reach the testing station on the conveyor belt with the same position accuracy. The In-Sight Micro 1400 intelligent vision system had to orient itself to certain predefined geometric features of the cartons in order to set and precisely determine the position of the labels and stickers in relation to it.

This process was made possible by the image-based PatMax pattern matching technology that determines all of the important position values without errors—even under variable lighting and position conditions, and despite changing angles, sizes and shading.

Lighting Technology is Key
The illumination of the testing station is provided by an LED ruby light. The trigger pulse for the In-Sight Micro is provided by a fluorescent sensor. This sensor recognizes the outer edge of the flat boxes using the fluorescent properties of the box in contrast to the non-fluorescent material of the conveyor belt.

In selecting the In-Sight Micro 1400, the packaging experts of Artur Theis were also impressed by its small size (30 x 30 x 60 mm). The complete and fully self-contained system is particularly well-suited to measuring, guiding, inspecting, counting and identifying products on fast-moving production lines. It also offers particularly flexible mounting options.

An important part of the intelligent vision system is the Cognex image processing library. Using this library, the operating software can be used for an extremely wide variety of image processing tasks.

The calibration of new products in Artur Theis’ new machine, for example, is very simple and can be carried out by the machine operators themselves. For new products, they simply set a characteristic feature of the packaging in relation to a characteristic feature of the sticker using the Cognex In-Sight Explorer software that comes with the In-Sight Micro. Based on the stored master job, product changes can be performed in just a few minutes, even for completely new folding boxes.

For more information, visit: www.cognex.com