| 摘要 |
PURPOSE:To compact a whole device by reducing the number of parts concerning the belt drive device capable of detecting and adjusting biased movement automatically. CONSTITUTION:A photosensitive belt 6 is suspended free to travel on three pieces of first, second and third rollers 3, 4, 5. A biased movement detection member 28 is arranged on the shaft end part of the third roller 5, and when the photosensitive belt 6 makes biased movement and makes contact with the biased movement detection member 28, one shaft end part of the third roller 5 is displaced by using rotation torque of the biased movement detection member 28 and initial biased movement is cancelled. Tension arms 17, 18 are installed between both shaft end parts of the second roller 4 and the third roller 5, and a long hole 18a extending toward the displacement direction of the shaft end part is formed on the tension arm 18. A tension spring 19 to give specified belt tensile force to the photosensitive belt 6 by giving energizing force to increase distance between the axial line of the third roller 5 and the axial line of the first roller 3 is connected to each of the tension arms 17, 18. |
