Register sensors such as the RS25 from SICK are capable of detecting control marks printed on paper webs at full production speed. If a sensor detects that the colors do not line up exactly on top of one another, whether lengthwise or sideways, this information is used for automatically correcting printouts, for example. ATEX approval means that the RS25 is suitable for use explosion areas. And with the real-time Ethernet POWERLINK fieldbus the new RS25 register sensor is incredibly fast and precise.
From the optical head to the evaluation unit via LED light from a fiber-optic cable
In the RS25, the optical head and evaluation unit are separate; they are connected by a 3.2 m long fiber-optic cable. This means that printing marks can even be detected in tight spaces in the printing machine. The sensor can be operated directly and its status LEDs read at a glance – all at the same time. This concept made it possible to certify the overall RS25 system for use in explosion areas.
As a means of attaining the maximum possible detection reliability between the mark and the background for each contrast, the RS25 features a multi-colored LED. This illuminates the print mark with red, green, and blue emitted light. The register sensor then uses the color LED that achieves the highest signal level: This guarantees detection results with maximum reliability for up to 20 different color marks. In addition, the repeatability is extremely high: The precision of the RS25 is below 40 µm and, therefore, ensures that the individual colors are layered over one another with the high levels of precision during multi-colored printing. The adjustable reading window of the RS25 compensates for missing color marks and enables fine-tuning to be carried out at any time during the printing process. This rules out unclear or blurry print images, as well as color deviations.
Detecting and transmitting color information at high speed
With a switching frequency of 80 kHz, the new register sensor from SICK achieves extremely fast response times. The integrated real-time Ethernet POWERLINK connection supports quick and safe data exchange with the automation system for the printing machine. Another advantage of the RS25 is the option to embed register monitoring into the control system. This opens up the possibility of creating additional, flexible register regulation solutions.
Sensor solutions for the printing industry
The addition of the RS25 has allowed SICK to expand its sensor portfolio for providing solutions to include detection tasks in the printing industry. High-performance sensors with different physical operating principles are available for all three parts of the process – prepress, press, and postpress – thus enabling the paper feed to be monitored, the printing process to be controlled, and processes for cutting, pressing, folding, gluing, and material handling to be detected. Many of these sensor series are also suitable platforms for developing special solutions on request in order to optimize the processes throughout the printing industry supply chain.