Abstract: A laser beam emitting device is provided for use, for example, in a laser beam printer. The device includes a single laser diode for emitting a laser beam having an output power level that is dependent on a driving current supplied to the laser diode. Two laser diode drivers are connected to the single laser diode and can be individually energized to drive the single laser diode to emit a laser beam that can have different output power levels. A selector is connected to the drivers for producing one of a plurality of selecting signals corresponding to the different output power levels, respectively, to select and energize one of the drivers.

Abstract: A laser beam controller having a laser beam emitter for emitting a laser beam and a beam receiver which receives the laser beam emitted from the laser beam emitter and outputs a light receipt signal corresponding to a signal level of the laser beam. The laser controller includes a reference signal outputting device for outputting a reference signal in accordance with an environmental humidity of the laser controller. A comparator compares the light receipt signal of the light receiver with the references signal. A control device controls the output of the laser beam emitter in accordance with the comparison result of the comparator.