Patent ID: 8346111

Claim:
An image forming device comprising: an imaging part configured to form toner images having colors different from each other on a plurality of latent image carriers; a belt unit having an endless belt member and a rotating body configured to move the belt member along with its rotation; a transferring part configured to superimpose and transfer the toner images formed on the plurality of the latent image carriers onto a surface of the belt member or onto a recording member retained on the surface; a driving motor serving as a drive source of the rotating body; and a controlling part configured to control the imaging part, the transferring part, and the driving motor; wherein the controlling part executes: a writing position correcting process configured to reduce a positional displacement of each color toner image by individually correcting each latent image writing position of the plurality of latent image carrier based on the amount of positional displacement of each color toner image in a color shift detecting image composed of at least two color toner images formed by the imaging part and the transferring part under the control of one of a constant motor speed control configured to drive the driving motor at a predetermined target rotational speed and a constant belt speed control configured to move the belt member at a predetermined target belt speed, and a speed correcting process configured to correct either the target rotational speed of the driving motor in the constant motor speed control or the target belt speed in the constant belt speed control based on an amount of positional displacement of each color toner image in a color shift detecting image formed under the control of the other of the constant motor speed control and the constant belt speed control.