Patent ID: 7860422

Claim:
An image forming apparatus comprising: a rotation body which is used for transferring an image, a drive section which rotates the rotation body, a control section which sends a control signal to the drive section to control a speed of the rotation body, a test signal generating section which generates a test signal and adds the test signal to the control signal; an angular velocity detecting section which detects an angular velocity of rotation of the rotation body; and a transfer function calculating section which obtains a latest transfer function of a rotation system including the rotation body and the drive section, based on the angular velocity of rotation detected by the angular velocity detecting section, and the test signal generated by the test signal generating section, wherein the control section controls the drive section, based on the latest transfer function obtained by the transfer function calculating section wherein the control section comprises a repeat control section, which is previously provided with an inverse filter, the inverse filter being based on an inverse function of the transfer function, and outputs the control signal obtained by making information of a specified target angular velocity pass through the inverse filter, wherein the transfer function calculating section sends to the repeat control section a parameter value for changing, based on the latest transfer function, the inverse filter into an inverse filter for the latest transfer function.