Patent ID: 7648134

Claim:
A paper supply device comprising: a paper supply cassette to load a printable medium; a pickup unit to pick up the printable medium loaded in the paper supply cassette sheet by sheet; a paper supply plate and a press spring arranged to bias the loaded printable medium toward the pickup unit; at least one first restraining device to restrain the paper supply plate when the pickup unit picks up the printable medium and to release the paper supply plate when the pickup unit does not pick up the printable medium; a second restraining device to permit the pickup unit to move vertically when the pickup unit picks up the printable medium and to restrict the vertical movement of the pickup unit when the pickup unit does not pick up the printable medium; and an elastic member to bias the pickup unit toward the printable medium so as to provide the pickup unit with a pickup force when the pickup unit picks up the printable medium, wherein the pickup unit comprises: a rotating shaft rotating due to a driving source; a paper supply roller coupled to the rotating shaft; a pickup roller disposed above the printable medium at a distance from the paper supply roller, to pick up the printable medium in conjunction with the paper supply roller; a pickup frame to support the pickup roller; and a lifting member connected to the pickup frame or a shaft of the pickup roller to move the pickup roller up and down; and wherein the second restraining device comprises: a second rotating cam coupled to the rotating shaft; a restraining member to advance and retreat by operation of the second rotating cam and having a restraining protrusion to restrain or release the lifting member; a second restoring spring to bias the restraining member toward the second rotating cam; and a restraining recess formed at the lifting member so as to allow the restraining protrusion to fit into the restraining recess to be latched.