42 n PACKAGING AND PRINTING January 2026 www.drivesncontrols.com Dual-camera system checks labels printing at 5m/s The Austrian firm CCL Label prints cylindrical labels on flexible film for use on round or oval containers, such as bottles. As well as carrying product and consumer information, the labels carry danger warnings, where applicable The thin transparent films are first printed using web offset and gravure printing processes, and then processed into cylindrical film sleeves. CCL Label has set itself the goal of reducing waste in its printing operations, and optimising the set-up of its print jobs, with the aim of not only saving material, time, energy and costs, but also making environmental improvements. Traditional colour control elements cannot be used on the sleeves, so the challenge was to develop an inspection system that could detect not only printing defects, but also provide in-line colour measurements across the full print image. The colour inspection specialist Virona teamed up with the machine vision supplier Chromasens to develop a system for CCL that provides precise print inspection and colour measurements. It consists of two systems using identical cameras and lenses, but with different lighting configurations. For the inline colour measurements, they developed a system based on high-speed Chromasens colour linescan cameras. The system measures colour values in the printed images inline. The colour is measured across the entire print width, for every point in the printed image, which is not possible using conventional colour measurement systems. Homogeneous dark field illumination and a motorised cylinder with a neutral background allow reliable and traceable colour measurement. The second camera system detects printing errors and works with background lighting optimised for transparent film materials. The two systems are housed behind one another in a mechanical frame, thus ensuring precise alignment, including lighting and guidance of the film web. In each system, two allPIXA evo linescan cameras with an 8k resolution together cover a 1060mm-wide web. A 300 dpi resolution can detect the smallest defects. Line rates of up to 100kHz allow 5m of printed foil to be inspected every second. To ensure consistent resolution in the transport direction, even at if web speeds vary, the camera regulates the line frequency based on the web speed, using a rotary sensor which transmits readings to the camera. The calibration process is the key to the new system and means that measurements using handheld spectral measuring devices are no longer needed. The tri-linear linescan cameras deliver RGB values, which are converted to Cielab values in real time using stored calibration data. This requires fast calculations based on precise colour calibration of the entire system. Colour calibration of the web-fed printing press was a challenge. Using a patented process, calibration for roll-to-roll printing has been adapted to allow CCL Label to perform colour calibration easily and reliably. The images captured are evaluated automatically, allowing even minor errors and colour deviations to be detected. Any printed areas with errors are highlighted and the colour control parameters are adjusted according to the measured colour value differences The precise colour measurements and reliable defect detection achieved by the new system has improved the print quality and cut reject rates. Wastage is up to 50% lower, leading to lower costs and more sustainable production. Set-up times when changing products have been shortened. The higher efficiency is also allowing shorter operating times and thus fewer work shifts. n The printing industry faces the dual challenge of delivering high quality, while cutting waste and optimising production processes. An Austrian label printing specialist has installed an inline inspection system that detects errors at an early stage and thus ensures quality. It performs both colour measurements and print inspection. The label inspection system uses pairs of linescan cameras to inspect up to 5m of printed foil every second
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