Technology enabling the transport of lightweight paper in the toner transfer area
In recent years, increasing importance is being placed on the ability to print a wide range of jobs in small lots through POD (print on demand), and thus demand for digital presses with superior performance and quality is increasing as well. Specifically, in addition to demand for high print quality, there is also demand for increased productivity through high-speed printing, as well as support for a diverse range of paper types, from lightweight to heavyweight paper. FUJIFILM Business Innovation has developed technology enabling the transport of lightweight paper in the toner transfer area, which excels at handling thin paper while at the same time allowing for high-speed printing.
In digital presses employing the xerographic method, toner is transferred from the intermediate transfer belt to the paper by an electric field during the imaging process. As a result of this, the paper is charged with static electricity and, particularly in the case of lightweight paper, is likely to become stuck to the intermediate transfer belt, which leads to paper jams. To address this problem, we optimized the structure of the toner transfer area and the electrical properties of its component items, thus drastically reducing the effect of static electricity on the paper after it is output from the transfer area. As a result, it is unlikely for paper jams to occur even when lightweight paper is used, enabling more stable paper transport, as shown in Fig. 1. With this technology, not only are we able to provide support for a diverse range of paper types, with some of our color on-demand publishing systems supporting paper ranging from 52 g/m2 (lightweight paper) to 350 g/m2 (heavyweight paper), but we are also able to deliver high productivity, with speeds of 100 pages per minute / 80 pages per minute.
Fig. 1: The structure of the technology enabling the transport of lightweight paper in the toner transfer area
Generally, the amount of deformation of a sheet of paper in the direction of gravity is dependent on the stiffness of the paper. When a sheet of paper is pinched horizontally in the transfer area, the amount of deformation is low for paper with a high basis weight. However, in the case of paper with a low basis weight, which lacks stiffness, the paper bends greatly to lie along the curve of the transfer roll below, as shown in Fig. 2. To prevent this from happening, we designed the structure of the toner transfer area to ensure that the lead edge of a sheet of paper is separated from the transfer roll when it is output from the transfer area. In addition, we also engineered the electrical properties of the component items of the transfer area to ensure that paper is transported after being output from the transfer area, without it being pulled toward the intermediate transfer belt due to the effect of the electric field.
Fig. 2: A diagram showing the position of a sheet of paper when output from the transfer area