Paper feeding device and image forming apparatus

A paper feeding device comprising:

• a paper feed tray configured to move with respect to an image forming apparatus body and house a recording medium, the paper feed tray includes a liftable paper placing portion on which recording media are placed and a lifting mechanism configured to lift the paper placing portion within the paper feed tray;
• a paper feeding roller configured to rotate in a given direction for a delivery of the recording medium housed in the paper feed tray in a set state in which the paper feed tray occupies a given position with respect to the image forming apparatus body;
• a drive transmission mechanism configured to perform drive transmission from a driving source to the paper feeding roller, wherein:
• the drive transmission mechanism includes a drive member that is provided on the image forming apparatus body side and is driven to rotate by the driving source so as to rotate the paper feeding roller in the given direction, and a driven member that is provided on the paper feed tray side, forms a contacting state by contacting the drive member when the paper feed tray is set into the set state, and forms a coupling state in which the driven member rotates the paper feed roller in the given direction when the driven member is coupled to the drive;
• and
• a controller configured to, after the paper feed tray is set into the set state and before a delivery instruction of the recording medium housed in the paper feed tray is output, rotate the driving source to perform relative rotation between the drive member and the driven member in the contacting state, and to further rotate the drive member and the driven member in the coupling state,
• wherein the controller is configured to determine a position of the paper placing portion within the paper feed tray based on an upper limit sensor, at the time of power-on, to determine whether to set the coupling state between the drive member and the driven member,
• the drive member has a plurality of projecting portions along a circumferential direction thereof, and the driven member includes recessed grooves to which the projecting portions can fit in the circumferential direction, and
• when the drive member and the driven member are coupled to each other, a fitting portion is formed via projecting portions of the drive member and recessed grooves of the driven member meshing together with each other.