Patent ID: 8731438

Claim:
An image forming device, comprising: a device main body having a driving source generating a driving force; a cartridge that is formed to be detachably attachable to the device main body and to include a rotation body provided to rotate by receiving the driving force from the driving source; a main body transmission unit that is provided in the device main body, the main body transmission unit being configured to rotate about a first rotation axis by receiving the driving force from the driving source; a main body joint unit that is supported by the main body transmission unit, the main body joint unit comprising a projected portion and being configured such that, in accordance with rotation of the main body transmission unit, the main body joint unit rotates about a second rotation axis which is allowed to intersect with the first rotation axis; a cartridge transmission unit that is provided in the cartridge, the cartridge transmission unit being configured to be able to rotate about a third rotation axis and to transmit the driving force from the driving source to the rotation body by rotating about the third rotation axis; and a cartridge joint unit that is supported by the cartridge transmission unit, the cartridge joint unit comprising a recessed portion configured to receive the projected portion of the main body joint unit, the recessed portion comprising a tapered surface configured to guide the projected portion of the main body joint unit, wherein the cartridge joint unit is configured to be able to rotate about a fourth rotation axis which is allowed to intersect with the third rotation axis, and configured to rotate coaxially with respect to the main body joint unit and to cause the cartridge transmission unit to rotate when the main body transmission unit rotates in a state where the cartridge is attached to the device main body and the cartridge joint unit is coupled to the main body joint unit, wherein the projected portion of the main body joint unit comprises: a fitting part; and a protrusion formed on an outer surface of the fitting part to protrude outward in a direction orthogonal to the second rotation axis, wherein the recessed portion of the cartridge joint unit comprises: a receiving part formed to have a concave shape to receive the fitting part of the main body joint unit along the fourth rotation axis; and an engagement groove formed to engage with the protrusion formed on the outer surface of the fitting part and to be inclined such that a length and width of the engagement groove defines a plane parallel to the fourth rotation axis and a centerline of the engagement groove is set within the plane at an angle to a line parallel to the fourth rotation axis, and wherein the cartridge joint unit further comprises a cartridge joint unit protrusion that is aligned on the fourth rotation axis with the protrusion formed on the outer surface of the fitting part, when the cartridge joint unit and the main body joint unit are in a coupled state.