| 摘要 |
PURPOSE:To control quantity of light based on the intensity of the real quantity of the light of a laser beam cast from a semiconductor laser by receiving a front beam cast from the semiconductor laser on a single point through a curved mirror surface formed on the part of the mirror surface of a polygon mirror. CONSTITUTION:The pair of the curved mirror surfaces 1a and 1b is provided on the polygon mirror 1, reflects the front beam FB cast from the semiconductor laser 30 on the single point, and leads its reflected light 3 to a photodiode 5 through a mirror 2. Then, the signal of the intensity of the quantity of the light equivalent to the front beam FB is outputted from the photodiode 5, a driving current is controlled till the output of a comparator 37 goes to '0', and the driving current is controlled to obtain the quantity of the light which is previously set. Thus, the control of the quantity of the light corresponding to the front beam FB can be executed, so that the quantity of the light of the semiconductor laser 30 can be adjusted with a value approximate to a laser light intensity exposing a photosensitive drum 12. |
