| 摘要 |
PURPOSE:To enhance the ability of control of prevention of side slip of an endless image-transfer belt or the like by providing a position detecting pattern in which triangles having their apexes directed toward the axial direction of a drive roller are successively arranged, on one side end part of the belt in the direction of belt conveyance, and by controlling the degree of side slip of the belt in accordance with a signal obtained from the pattern. CONSTITUTION:Marks having a reflectance which is different from that of the outer surface of a belt 1, such as black isosceles triangles or the like, are successively arranged on one side end part of the outer surface of the belt 1 over the entire circumference of the belt in the direction of conveyance of the belt 1 so as to obtain a position detecting pattern 4 which is detected by a reflection type photosensor 3. For example, estimating that a position (a) is a reference position, a position (b) or (c) is detected in accordance with a side slip of the belt 1. A degree of the side slip is computed in accordance with a detection signal from the photosensor 3 so as to control a belt shift means in a direction in which the side slip can be eliminated. With this arrange ment, it is possible to reduce the range of belt meander. |
