Abstract: An apparatus for stably fixing a reflection mirror of a laser scanning unit to a frame. The apparatus comprises a reflection mirror, a frame receiving and supporting the reflection mirror, fixing pieces disposed in the frame and having a connection surface which is slanted at a predetermined angle so as to tightly contact one side of the reflection mirror, support blocks supporting the other side of the reflection mirror, and clamps clamping the fixing pieces and the reflection mirror in order to tightly contact the reflection mirror and the connection surfaces of the fixing pieces.

Abstract: A laser beam isolation apparatus of a laser printer includes a blocking portion formed on the laser scanning unit to be moved between a blocking position to block a passing hole of the laser scanning unit and an open position to open the passing hole, a guide portion mounted in the laser scanning unit relative to the blocking portion, guiding the blocking portion to move between the blocking position and the open position, and an operating portion formed on the developer unit. The operating portion is operated to move the blocking portion along the guide portion. During a removal of the developer unit, the blocking portion that blocks a laser beam of a laser diode from being emitted out of the laser scanning unit is moved to the blocking position by its own weight.

Abstract: An apparatus for stably fixing a reflection mirror of a laser scanning unit to a frame. The apparatus comprises a reflection mirror, a frame receiving and supporting the reflection mirror, fixing pieces disposed in the frame and having a connection surface which is slanted at a predetermined angle so as to tightly contact one side of the reflection mirror, support blocks supporting the other side of the reflection mirror, and clamps clamping the fixing pieces and the reflection mirror in order to tightly contact the reflection mirror and the connection surfaces of the fixing pieces.