Fast, reliable detection of printing plate allocation errors with intelligent camera from Leuze electronic

Leuze: KBA, one of the world’s leading printing press manufacturers, has come up with a way of preventing printing plate allocation errors: The new printing plate detection system Plate-Ident. The technology behind the new development is an intelligent camera system with image processing capability which was developed specifically for KBA by Leuze electronic.

The pressure is on for newspaper print businesses

The pressure on modern newspaper producers to be abreast of the very latest news developments means that hectic last-minute rushes and night shifts are the norm. When production of the press proofs starts in the middle of the night, everything has to be just right. Printing plate allocation errors – in other words pages in the wrong order – can have fatal consequences in terms of print waste and adherence to deadlines. Having to stop the press again to correct the plate assignment means losing productive time and can even result in delivery delays. In many cases, new plates also have to be fitted, which entails additional waiting periods. Depending on the size of the press system, avoiding this type of allocation error, which happens all too easily given the hectic pace of work, can offer substantial potential for savings. “The printer often only recognizes a plate allocation error when checking through the first proofs”, explains Andreas Birkenfeld, Head of System Engineering Design at Koenig & Bauer AG (KBA) in Würzburg. This is a risk which – depending on the scope and degree of distinction between different newspaper editions – has the potential to be an integral part of the day-to-day running of a printing operation involving several thousand plate changes daily.

Seamless workflow chain

With the declared aim of changing this situation, KBA began work in cooperation with sensor specialists from Leuze electronic on the development of an automatic plate detection system to carry out a preventive check for correct plate allocation. The automation module, which has been named Plate-Ident, closes the gap in the work flow chain right to the press, ensuring unequivocal assignment of plates to the right printing position. The system works using a system of camera-based checking of data matrix codes on the printing plates.

The decision to opt for data matrix coding was down primarily, according to Birkenfeld, to the minimal contrast difference and the density of information, both of which make stringent demands on any automatic reading process. The arrangement of the data matrix code in horizontal and vertical fields permits a high information density to be achieved in a minimum of space, and also makes it possible for the scanning devices to read the information in any position. Another factor guaranteeing reliable scanning is the high data logging capacity which allows data to be located in multiple positions (ECC = Error Checking and Correcting). Even assuming 25% illegibility of data fields, the information can still be reliably scanned. Legibility in any position is instrumental in ensuring that four codes can be scanned simultaneously in the Plate-Ident system in their respective different positions. “The data matrix codes are also exposed during CtP pre-press production”, explains Birkenfeld, “ensuring that the printing plates can be positively identified right from the time of their manufacture”.

Customer-specific development

The plates are checked directly at the infeed shafts of the automatic KBA PlateTronic plate changing system. This is done using an intelligent camera with image processing capability engineered by Leuze electronic specifically for this assignment. Based on its comprehensive problem solving expertise in the field of industrial image processing and identification, Leuze developed both the hardware and software specifically for this application. “With a minimal reading distance of just a few centimetres and special integrated lighting designed to address the needs of the printing plates, we succeeded in achieving outstanding performance”, confirms a satisfied Birkenfeld. What matters to him under the bottom line is reliable error detection which is indicated immediately over the Ethernet network at the control panel in the printing press control centre.

If an incorrect printing plate is mounted in the rush to prepare for printing, this can now be corrected by the operator before the plates are finally secured in the press, eliminating the damage caused by subsequent exchanging of plates and putting an end to wasted print and / or unscheduled press standstill. The camera system supplied by Leuze electronic in the Plate-Ident plate detection system allows KBA to be confident that the right plates really are secured in the right places in the press prior to printing.