IMAGE READING DEVICE

To solve a problem in which: when performing front-and-back image position adjustment for images larger than the A3 size, an image forming apparatus is required to be able to read an image equal to or larger than the A3 size in a main scanning direction and simultaneously read the front and back sides of a sheet; however, when line sensors are arranged on the front and back of the sheet in a zig-zag manner in the main scanning direction, the number of line sensors and control elements is increased, which leads to a large increase in cost.SOLUTION: An image reading device arranges line sensors while shifting from each other in a main scanning direction and inverts a sheet to read the sheet twice, thereby enabling simultaneous reading of a portion where reading elements overlap on the front and back of the sheet, and thus can read images equal to or larger than the A3 size without moving the sheet in a direction orthogonal to a conveyance direction.SELECTED DRAWING: Figure 1 【課題】画像形成装置において、Ａ３サイズよりも大きい画像の表裏画像位置調整を行う際、Ａ３以上の主走査読み取りが可能で、表裏同時読取が可能であることが求められるが、表裏の主走査方向に千鳥状にラインセンサを配置すると、ラインセンサを及び制御素子の増加により、コストが大幅に増加してしまう。【解決手段】ラインセンサを表裏で主走査方向にずらして配置し、紙を反転して２度読む構成にすることで、読取り素子が表裏で重なる箇所は同時読取を行うことができ、紙を搬送方向直交する方向に移動させることなくＡ３以上の画像を読み取ることが可能になる。【選択図】図１