BELT MEANDERING PREVENTING DEVICE AND IMAGE FORMING APPARATUS INCLUDING THE SAME

PROBLEM TO BE SOLVED: To detect displacement of a belt in its width direction in a wide detection range at a high detection resolution by using a plurality of inexpensive sensors. SOLUTION: The belt meandering preventing device corrects the displacement of an intermediate transfer belt in the belt width direction based on the detected result of an edge sensor 24 that detects an amount of displacement of the intermediate transfer belt 61 in the width direction. The edge sensor includes a plurality of optical sensors 24e and 24f that output signals of output levels corresponding to the proportions in an optical path of a light-shielding part 24d moving interlocked with the displacement of the intermediate transfer belt in the width direction. The optical sensors are arranged such that the output levels of the optical sensors change as the belt is displaced in the belt width direction in a predetermined high-resolution detection range. The output signals of the optical sensors are combined such that the rate of change of an output level with respect to the amount of belt displacement within the range becomes greater than the rates of the respective optical sensors. The combined signal is detected as the amount of belt displacement. COPYRIGHT: (C)2011,JPO&INPIT