| 摘要 |
A belt feeding unit includes a rotatable belt; a first stretching roller; a second stretching roller including a stretching portion; a supporting portion for supporting the stretching portion while permitting movement of opposite end portions thereof up and down; a rotatable portion coaxial with the second stretching roller; wherein when the belt shifts in the longitudinal direction, the belt contacts the rotatable portion to rotate the rotatable portion, thus tilting the second stretching roller about the supporting portion relative to a rotational axis of the first stretching roller. |
