Patent ID: 7986906

Claim:
An image-forming device comprising: a plurality of image carrying members provided for respective colors and aligned in a first direction in a main casing; a plurality of developing units provided in one-to-one correspondence with the plurality of image carrying members, each of the plurality of developing units including a developer carrying member that supplies developer to the corresponding image carrying members; first and second contact/separation members linearly movable in the first direction, in a second direction perpendicular to the first direction, the first contact/separation member and the second contact/separation member being disposed one on either side of the plurality of developing units in opposition with each other, the first contact/separation member being disposed on one side of each developing unit, and the second contact/separation member being disposed on the other side of each developing unit, and a synchronous moving mechanism that linearly moves the first and second contact/separation members in synchronization with each other, wherein each of the first and second contact/separation members includes a plurality of cam parts in one-to-one correspondence with the plurality of developing units, the first and second contact/separation members linearly move in the first direction to move at least one of the plurality of developing units between a contact position where the developer carrying member contacts the corresponding image carrying member and a separating position where the developer carrying member separates from the corresponding image carrying member, the developing unit is on the corresponding cam part at the separating position and the developing unit is out of the corresponding cam part at the contact position, and the plurality of cam parts is configured to be arranged at intervals in the first direction so that one developing unit remains at the contact position and the remaining developing units are moved to the separating positions in a case that the first and second contact/separation members linearly move by a predetermined distance; wherein the synchronous moving mechanism includes a first rack gear formed on the first contact/separation member, a first pinion gear engaging with the first rack gear, a second rack gear formed on the second contact/separation member, a second pinion gear engaging with the second rack gear, and a coupling shaft coupling the first pinion gear to the second pinion gear.