LIGHT BEAM CONTROL DEVICE AND IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To control, even if a response speed of a photodiode for monitoring a light amount of a light beam to be irradiated from a laser diode is low, the light amount of the light beam to a target light amount.SOLUTION: If it is determined that a candidate driving current serving as a candidate for an initial value of a driving current is within a range of a target driving current (Yes in step S3), a first light amount control unit determines that a photodiode is normal, and ends first APC (Automatic Power Control) using the candidate driving current as an initial value (step S4). If it is determined that the candidate driving current is outside the range of the target driving current (No in step S3), the first light amount control unit does not end the first APC, and re-executes the first APC by making a sampling period longer than before the re-execution of the first APC (step S10). If it is determined that the candidate driving current obtained by the re-execution of the first APC is within the range of the target driving current (Yes in step S12), the first light amount control unit determines that the photodiode is normal, and ends the first APC using the candidate driving current obtained by the re-execution of the first APC as an initial value (step S4).