Abstract: A belt cartridge in a printing apparatus, including a base board attachable to or detachable from the belt unit to be operative to face the belt unit at one surface, a support unit movably installed on the base board to be operative to selectively contact the inner surface of the photoreceptor belt, and a moving mechanism which moves the support unit toward the base board and isolates the support unit from the base board.

Abstract: A roller driving apparatus having a roller contacting and rotating a photo-receptor web in a printer is provided. The apparatus includes a support shaft coaxially fixed to the roller and having a coupling groove formed in an outer circumferential surface thereof in a radial direction, a rotation member inserted around the support shaft, a coupling member coupled to the rotation member to protrude and retreat with respect to an inner circumferential surface of the rotation member, and inserted in the groove of the support shaft when protruding from the inner circumferential surface of the rotation member; a spring elastically biasing the coupling member in a direction to protrude from the inner circumferential surface of the rotation member, a motor, and a power transfer unit transferring the power from the motor to the rotation member to rotate the rotation member.

Abstract: A laser printer which includes a photosensitive belt of a loop type having a seam at a portion where the ends overlap. The photosensitive belt circulates around a driving roller, a steering roller and a transfer backing roller, as well as passes between the transfer backing roller and a transfer roller. The laser printer also includes a distance controller which moves the transfer backing roller toward and away from the transfer roller.