Printers and copiers often have a photo-sensitive member which receives an image, and an intermediate transfer member, often with a heated blanket, which receives the image from the photo-sensitive member and transfers it to sheet of paper or other printing media on an impression roller. (The printing media will henceforth be referred to as “paper,” but any printing media should be understood.) The intermediate transfer member often has a delicate surface, for example the heated blanket may comprise a release surface with a soft conforming layer underneath, which allows the surface to press against the impression roller with uniform pressure. These characteristics of the intermediate transfer member produce good images on the printing media, but also mean that its surface may be damaged relatively easily, and such damage may require a time-consuming and expensive replacement of the member. Even for different structures, the intermediate transfer member (often in the form of a blanket) is subject to damage from excess pressure and/or from toner that is left on the release surface too long.
One cause of such damage is paper sticking to the blanket. Normally, paper is fed onto the impression roller and held there with grippers. If the paper is misfed for any reason, then the paper may stick to the blanket of the intermediate transfer member after the image is printed. The printer must then be stopped, opened up, the paper removed, and the ink on the blanket (which in normal operation gets completely transferred to the paper) must be cleaned off. Delay in removing the ink from the blanket may result in the ink drying onto the (generally heated) blanket, which must then be replaced. Ink may also remain on the intermediate transfer member if, as a result of the paper misfeeding, at least part of the intermediate transfer member presses directly against the surface of the impression roller, without any paper in between. If the paper is folded or wrinkled as a result of the misfeed, it may dent the blanket, also making it necessary to replace the blanket. If paper is not released on time from the impression roller, then two sheets of paper may end up on the impression roller, which can hurt the blanket.
Because paper misfeeds are potentially so damaging, it would be desirable to prevent any events which could cause a misfeed, even relatively rare events.