| 摘要 |
PURPOSE:To compensate the fluctuation in an optical output with high accuracy by measuring an optical output fluctuating characteristic at the start point of optical scanning, and calculating a required driving current from the result to adjust the control current of a sample hold feedback system. CONSTITUTION:A laser beam 2 from a semiconductor laser 1 is scanned by a rotary polygon mirror 4, collected on a photoconductive body drum 6 and dot pattern is recorded on plain paper. The modulation timing of scanning light is controlled with high accuracy by detecting an optical scanning timing at each time in this case and transmitting the result of detection to the laser 1 via a control system 20. The optical output of a beam 2' irradiated from the back side of the laser 1 during the flyback period of the scanning light is measured by a solar battery 10. The time versus optical output characteristic is measured 21 from the measured optical output via the sample hold system 11, the amplitude coefficient is calculated 22 from the result of measurement and the driving current of the laser 1 is adjusted from the calculated value at a correcting amount calculation circuit 23 to make the optical output constant. |
