| 摘要 |
PURPOSE:To correct decrease of luminous efficiency following generation of heat of a joint of a semiconductor laser by a method wherein a sampling comparison control signal is corrected with an integral value obtained by integration of an image signal, and a driving current of the semiconductor laser is controlled. CONSTITUTION:An output of a monitor diode 4 is converted by voltage with an amplifier 5a, and is compared with a level (reference level) of a LD power control signal Pc with a comparator 5b. When it is a level of a lower output than the reference level Pc, a light output control part 7 is made to an emission level of a high output. When it is a level of a high output, the light output control part 7 is made to the emission level of a low output. Together therewith, when a start signal (BD signal) BD is on, an integrator 6 is discharged to 0V and integrates an output of a monitor diode 4 of the amplifier 5a. Since the light output control part 7 is composed of a summing amplifier, a form in which an integral signal IS of the integrator 6 is added to an output SC of a gate 5c is outputted as a light output control signal LCS to an LD driver 3, and a driving current is controlled. |
