Abstract: In response to a print end instruction from a controller, a development controller checks if the ink density is proper. If the ink density is out of proper range, a circulation path switching valve is turned on to continue ink density adjustment processing even after printing ends. The ink circulation path is switched to allow the ink to flow directly to an ink tank. The ink stored in a supply path from the valve to a developing unit and in the developing unit is returned to the ink tank. In this state, the ink density adjustment processing is performed. A transmission type density sensor senses the current density of X %, and sends the density to the development controller. The development controller retrieves proper density range data of N %-M % from a density adjustment table and compares the sensed density with the proper density range data. If X %>M %, L ml of diluted ink solution is supplied by a supply pump. If X %<N %, K ml of ink dye is supplied by the supply pump.

Abstract: An object is to make it possible to compensate a forming position of an electrostatic latent image just after detection of a position of a photosensitive belt. A position control section has a timing compensating function to compensate output timing of an image signal to be outputted when the n+2-th line is scanned, on the basis of a difference between a position Cn of the photosensitive belt outputted from a position sensor section when the n-th line of the electrostatic latent image is scanned and a position Cn+1 of the photosensitive belt outputted from the position sensor section when the n+1-th line is scanned.