Paper Path Detection in Ink Jet Printers by Using Speed Perturbation Observer

As the speed of paper feeding processes in an ink jet printer is increased, the paper feeding mechanisms are usually prone to induce some paper transport problems such as paper jamming and slipping, and some mechanical problems such as gear cracking and chattering. Therefore, for ensuring printing qualities and for preventing destructive damages, the paper path detection in ink jet printers is required. In this paper, we explore the feasibility of using speed perturbation observer to detect paper path situations in an ink jet printer. Moreover, in comparing with the existing approaches, this paper presents an approach without additional sensors. The speed perturbation observer composed of a nominal plant, a low-pass filter, and an identification unit is developed to detect paper path situations during paper feeding processes. The design concept is based on the fact that external disturbances usually significantly affect the speed performances of an axial motion system. Since the paper feeding processes in ink jet printers are equivalent to that the interaction among paper and paper feeding mechanisms exerts external disturbances on the driven motor, it is interesting to detect paper path situations by estimating speed perturbations induced by different paper feeding actions. The proposed approach is implemented on an ink jet printer and two usual paper path situations are tested. The experimental results demonstrate that the proposed approach can accurately respond to the different paper path situations caused by different paper feeding actions.