COMPOSITE MACHINE

PROBLEM TO BE SOLVED: To solve the problem in which further improvement in operability is required since it is difficult to maintain excellent operability over the whole area when it is tried to widen a rotation area in a composite machine in which a document reading device is arranged on the upper part of an image formation device and the upper part of the image formation device is made openable by making the document reading device freely rotatable.SOLUTION: A composite machine comprises: a left one-way hinge 25 which is arranged in an image formation device body 21a; a left pinion gear 27 which rotates integrally with a rotation shaft; a first left rack gear 33a which is arranged in a rotation part (31, 13, 14, 11, 15) and engaged with the left pinion gear 27 when the rotation part rotates in a first rotation area; and a second left rack gear 33b which is engaged with the left pinion gear 27 when the rotation part rotates in a second rotation area different from the first rotation area, and is configured so that the rotation directions of the pinion gear 27 are different from each other between the first rotation area and the second rotation area when the rotation part rotates in one direction. 【課題】画像形成装置の上部に原稿読み取り装置を配置し、上部の原稿読み取り装置を回動自在にして画像形成装置の上方を開放可能に構成したものでは、回動領域を広くしようとすると、全域にわたって良好な操作性を維持するのが難しく、更なる操作性の向上が求められる。【解決手段】画像形成装置本体２１ａに配設された左ワンウェイヒンジ２５と、この回転軸と一体的に回転する左ピニオンギヤ２７と、回動部（３１，１３，１４，１１，１５）に配設され、前記回動部が第１の回動領域を回動するとき左ピニオンギヤ２７と噛合する第１左ラックギヤ３３ａと、前記回動部が第１の回動領域とは異なる第２の回動領域を回動するとき左ピニオンギヤ２７と噛合する第２左ラックギヤ３３ｂとを有し、前記回動部が一方向に回動するとき、第１の回動領域と第２の回動領域とで、ピニオンギヤ２７の回転方向が異なるように構成する。【選択図】図６