A hinge mechanism that supports a document conveyance unit such that the document conveyance unit can be opened and closed with respect to an image reading unit, the hinge mechanism comprising:
- a first member fixed to the image reading unit;
- a first shaft supported by the first member;
- a second member configured to rotate on the first shaft with respect to the first member;
- a second shaft disposed at a position different from a position of the first shaft and parallel to the first shaft, and supported by the second member;
- a third member configured to rotate on the second shaft with respect to the second member, the third member including a first pair of side plates and a first top plate connected to the first pair of side plates at a top side of the first pair of side plates;
- a third shaft disposed at a position different from the position of the second shaft and parallel to the second shaft, and supported by the first pair of side plates;
- a fourth member to which the document conveyance unit is fixed, and which is configured to rotate on the third shaft with respect to the third member, the fourth member including a second pair of side plates and a second top plate connected to the second pair of side plates at a top side of the second pair of side plates, and the fourth member being disposed such that the second top plate is positioned above the first top plate;
- a first urging portion that includes a first spring configured to apply torque in a direction in which the second member is opened with respect to the first member;
- and
- a second urging portion that includes a second spring configured to apply torque to the fourth member such that the fourth member rotates on the third shaft with respect to the third member;
- and
- wherein the second spring is disposed outside the second pair of side plates in an axial direction of the third shaft, below the first top plate, and above a lower edge of the second pair of side plates in a state where the second member is closed with respect to the first member.