A drawer unit includes: a drawer member allowed to shift toward a storage unit in an inserting direction, or shift from the storage unit in a drawing direction; a lock member rotatably supported by the drawer member; a first regulation member that engages with the lock member to regulate a shift of the drawer member when the drawer member is located at a first position; a second regulation member that engages with the lock member to regulate a shift of the drawer member when the drawer member is located at a second position; and an operation unit that receives a first operation that rotates the lock member in the drawing direction to allow engagement between the lock member and the first regulation member, and a second operation that rotates the lock member in the inserting direction to allow engagement between the lock member and the second regulation member.

An image forming apparatus includes an apparatus body, an image forming unit, an opening and closing cover, a fixed cover that constitutes a part of an exterior of the apparatus body with the opening and closing cover, and is configured to form a boundary portion with an upper edge of the opening and closing cover in a vertical direction, a positioning portion including a first engagement portion provided in the opening and closing cover, and a second engagement portion provided in the fixed cover, a first conveyance guide provided on the opening and closing cover, and a second conveyance guide provided on the fixed cover. The first engagement portion and the second engagement portion are configured to engage with each other to perform positioning of the opening and closing cover and the fixed cover in the vertical direction and positioning of the first conveyance guide and the second conveyance guide.

A cover member attachment/detachment structure includes a first engagement part and a second engagement part. The first engagement part is formed in one of a portion to be protected or a cover member attached to the portion to be protected. The second engagement part is formed in the other of the portion to be protected or the cover member attached to the portion to be protected. The second engagement part is capable of engaging with the first engagement part. The first engagement part is made of magnetic material. The first engagement part is magnetically movable from an outside of the cover member without contact between a locking position where the first engagement part is engaged with the second engagement part and a lock releasing position where the first engagement part is disengaged with the second engagement part.

An image forming apparatus includes a unit horizontally insertable and drawable with respect to a main body frame, and a lock mechanism for the unit. The lock mechanism includes a lock member which has an engagement projection engageable with an engaged portion formed in the main body frame, and a biasing member which biases the lock member in a first direction toward engagement of the engagement projection with the engaged portion. Along with insertion of the unit, the lock member moves in a second direction, and when the unit is inserted to a predetermined position, biasing force of the biasing member causes the lock member to move in the first direction and the engagement projection engages with the engaged portion. By moving the lock member in the second direction, engagement between the engagement projection and the engaged portion is released to make it possible to draw the unit.

An image forming apparatus and a lock mechanism including a toggle mechanism capable of eliminating the problem of abnormal noise before and after a lock member passes a neutral point are provided. A lock mechanism includes a toggle spring that rotationally biases a toggle lever toward a standby position when the lever is between a standby position and a neutral point, and implements switching in a direction of the rotational biasing toward a locking position after the lever passes the neutral point. A projection and a locked portion of an engagement member are sandwiched by a toggle base and the toggle lever to maintain a contact state before and after the toggle lever passes the neutral point.

An apparatus body of an image forming apparatus has a first guide portion having an inlet shape corresponding to an outer shape of an engagement portion provided in a cartridge when seen in an attachment direction of the cartridge to the apparatus body and guiding the engagement portion, a second guide portion for guiding a positioning target portion which is provided on the cartridge for positioning an attachment completion position of the cartridge with respect to the apparatus body, and a movable member being at a regulation position at which a guiding path of the positioning target portion by the second guide portion is blocked is immovable from the regulation position unless being pressed by the engagement portion.

An apparatus body of an image forming apparatus has a first guide portion having an inlet shape corresponding to an outer shape of an engagement portion provided in a cartridge when seen in an attachment direction of the cartridge to the apparatus body and guiding the engagement portion, a second guide portion for guiding a positioning target portion which is provided on the cartridge for positioning an attachment completion position of the cartridge with respect to the apparatus body, and a movable member being at a regulation position at which a guiding path of the positioning target portion by the second guide portion is blocked is immovable from the regulation position unless being pressed by the engagement portion.

A snap ring is set to a set portion of a shaft of a rotator from a direction orthogonal to an axial direction of the shaft. The snap ring includes a first arcuate portion and a second arcuate portion facing each other, being elastically deformable in directions away from each other, holding the set portion by elastic deformation restoring force. One ends of the first and second arcuate portions are away from each other to form an insertion portion to insert the set portion. When the snap ring is not used, the first arcuate portion has a same radius of curvature as the second arcuate portion and the set portion, and a center of curvature closer to the second arcuate portion than the first arcuate portion, and the second arcuate portion has a center of curvature closer to the first arcuate portion than the second arcuate portion.

A controller is configured to, when forming an image on one sheet, in a case where a length of one sheet in a conveyance direction is larger than a first length, drive a moving mechanism to move a plurality of developing rollers from a separation position to a contact position, temporarily stop driving of the moving mechanism, and then, at a first timing, again drive the moving mechanism to move the plurality of developing rollers from the contact position to the separation position; and in a case where the length of the one sheet in the conveyance direction is smaller than or equal to the first length, drive the moving mechanism to move the plurality of developing rollers from the separation position to the contact position and then to move the plurality of developing rollers from the contact position to the separation position without stopping driving of the moving mechanism.

An image forming apparatus includes a transferred body to which a toner image is transferred, a transfer device, a contact-separation device, and circuitry. The transfer device transfers the toner image from the transferred body onto a recording medium. The contact-separation device includes a motor and drives the motor to move the transfer device away from or into contact with the transferred body. The circuitry causes the contact-separation device to move the transfer device away from or into contact with the transferred body. The circuitry moves the transfer device away from the transferred body to a first position during standby and locates the transfer device at a second position that is closer to a contact position at which the transfer device is configured to contact the transferred body than the first position in an interval between the recording medium and a succeeding recording medium.