Various aspects are described, such as a method for operating a level shifter, in which the level shifter is coupled to a first supply voltage and a second supply voltage different from the first supply voltage. A generating unit generates a bitmap corresponding to the designated edge face depending on a bookbinding condition. Good results are obtained with a developing solvent with at least 25 vol. The drive controller rotates the first roller at a constant circumferential speed at least in a state where the first and second rollers are in pressure contact with each other and rotates the second roller with a constant torque which is low enough for the second roller to stop rotating when the first roller stops rotating.