| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a detection device generating no detection error even when vertical fluctuation of a belt occurs, because a detection position error is generated by the vertical fluctuation of the belt when the direction of a floodlighting luminous flux is set slantwise to the belt running direction in the case where a reflection type photocoupler is used as a detection device, in a background wherein, in a color image forming device wherein a rotor, the belt or the like is used, color shift is generated in an image when rotation irregularities or belt running irregularities occur, and an encoder having an optical mark attached thereto is used in order to prevent the color shift, and driving control is performed by detecting a position error by an optical detection device and by performing feedback, to thereby remove the irregularities. <P>SOLUTION: Optical axes of a floodlighting part 23 and a light receiving part 24 of the photocoupler 22' are arranged in the vertical plane to the belt 3 running direction. Concerning the belt width direction, the axes are arranged slantwise on mutually reverse sides relative to the perpendicular to the belt surface. A just middle value between the maximum value and the minimum value of light receiving part outputs is used as a binarization threshold of the light receiving part outputs. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
