Safe-Ident Impurity

Guaranteed Detection of Impurities and Foreign Particles

Safe-Ident Impurity Kamera
Plastic film in focus: Since the working distance between the camera and the film is fixed, the size of the area that is analyzed by the image processing system varies depending on reel width and increase in reel diameter during production.
Our solution checks plastic film for impurities during wrapping or winding processes. The analysis takes place while the finished film is unwound from the reels in order to be trimmed and, where applicable, printed before being rewound on new reels. During this winding process, small insects of dirt particles can easily cling to the film. Safe-Ident Impurity quickly and reliably detects impurities larger than 2x2mm (0.078”x0.78”).

Wide Area of Application

A high-resolution line scan camera with a line frequency of up to 51kHz captures the process which is subsequently analyzed by our software. The line scan camera captures one image line at a time in high frequency. The individual lines are then joined together so that a two-dimensional image is created as the film moves underneath the camera. The resolution of the image width is thereby defined by the resolution of the camera sensors, the resolution of the image height is theoretically unlimited, therefore high-resolution images of the surface of the film can be taken. When utilizing adequate lighting, impurities can be made visible.

Different combinations of camera, optics, and lighting enable the system to deal with varying working distances, reel widths and environmental conditions. Using a line scan camera makes it easier to take images without any reflections, despite the challenges posed by the surface of plastic film.

Das System hat einen verschmutzten Bereich gefunden
Blob: The system found a small contaminated area to the left of the printed area (framed in pink).

Automatically Recognizing Relevant Areas

Pre-process algorithms enable an automatic definition of those areas of the image that should be checked for impurities. Margins that are not part of the film reel can thus be excluded from the analysis as well as specific areas on the foil, for instance, if these are printed, which might otherwise be classified as impurities.

The software analyses these limited search areas of the captured images and detects impurities that differ from the background in color and contrast in brightness. Safe-Ident Impurity is extremely precise in differentiating between dirt particles and other, non-critical irregularities on the surface, such as creases. This means an error is only triggered if there are actually insects or dirt particles on the surface of the film.

Clear Data Logging

The data derived from analyzing the image can be saved in clear form to guarantee a complete documentation for quality control. An individual storage directory can be created for each production process, in which the images are saved. The user can decide whether the images should be saved continuously or just when impurities are detected. Additionally, images can be saved either as raw data or with annotations.

Restricting User Access

Important parameters for defining the area of analysis or the kinds of impurities should not be tampered with accidentally or intentionally. Therefore, the software can restrict access for the machine operator.

Safe-Ident Impurity is already successfully in use in the control of plastic film production.

The user interface:

Safe-Ident Impurity User Interface
Automatic recognition of margins or print: the margins of the reel are marked in yellow, the printed area in pink. The image is only analyzed in between the yellow lines and the markings within the pink box are ignored.

Picture Credits: © Strelen