A multi-axis synchronous register control system for color rotogravure printer

Based on the automatic color register control for plastic film and aluminum foil in the flexible packaging and printing industry, this paper analyzes the commonly employed system solution of one main motor driving several printing roller stations. To meet the new demands of faster control response, better performance of correcting registration errors and tension smoothing, this paper proposes a new multi-axis synchronous color register control system that every printing roller controlled by AC servo motors independently. The system model about the multi-axis positions and material tensions is presented. The new expert control algorithm is discussed under that the material tension is maintained at a constant level. In addition, a photoelectric sensor as a printing marks detector, a digital line transport velocity sensor and the registration error calculations are introduced, to show the measurement method of color graphical registration errors and the implementation of the new register control system. The core units of the control system are industrial computer and DSP based controllers. The application on a prototype eight-color rotogravure printer shows that this control system is easy to operate and good in register control accuracy and stability.