US Patent 7726774 Image forming device capable of stably supporting carriage

A downward component force of a tensile force exerted on a timing belt at a belt coupling part and the weight of a carriage act upon a first sliding surface of a first guide member and a second sliding surface of a second guide member via a first sliding protrusion and second sliding protrusions. Since the center of gravity of the carriage is located between the first sliding protrusion and the second sliding protrusions, the carriage can be stably supported by the first and second guide members while the carriage remains stationary or moves at a constant speed in a main scanning direction.