Fixation control device

Abstract

A fixation control device is provided which controls the operation of a fixing unit having a heat roller and a press roller between which a sheet is passed. When copies are successively made on a plurality of narrow-size sheets, the temperature of the end portions of the press roller rises and, therefore, the difference between the temperatures of the end portions and the central portion of the press roller becomes greater. The greater temperature difference results in a diameter difference between the central portion and the end portions of the press roller due to thermal expansion, thereby reducing sheet transportation ability of the heat roller and press roller. However, the fixation control device of the present invention can compensate the reduction in the transportation ability by increasing the rotational speed of the heat roller and press roller when the temperature difference becomes greater.

Dependencies are inferred from the claim text.