LASER SCANNING UNIT HAVING AUTOMATIC POWER CONTROL FUNCTION

A laser scanning unit emits a laser beam for scanning a surface within a predetermined scanning range. The laser scanning unit has a laser diode, and a laser diode controller for controlling the laser diode to emit the laser beam. The laser beam has an intensity set in accordance with image data corresponding to one of a plurality of predetermined graduation steps within an intensity range defined by a first intensity and a second intensity greater than the first intensity. The laser scanning unit is further provided with a first adjusting system for adjusting the first intensity to become a first predetermined intensity, and a second adjusting system for adjusting the second intensity to become a second predetermined intensity. One of the first adjusting system and the second adjusting system is actuated during each scanning operation, and are actuated alternately during successive scanning operations.