| 摘要 |
PURPOSE:To invariably obtain optimum color images by providing an adjusting means which adjusts the laser light emission power of other laser units so that the surface potential of other photosensitive bodies is equalized to the surface potential of a photosensitive body irradiated with a laser beam when the laser power of the laser beam exceeds a specific control range. CONSTITUTION:Laser power irradiated from a laser unit 41c at an exposure point 11 is detected by a photodiode. When a control part 1 judged from the output of the photodiode 5 that there is laser power which can not generate a normal surface potential VL owing to the abnormality of the laser unit 41c, the surface potential VL at the exposure point 11 of a photosensitive drum 45c which is generated by the laser beam irradiated from the laser unit 41c is detected by a potential sensor 6. The target exposure potential VR of other photosensitive drums 45M, 45Y, and 45BK is set to said surface potential and a driving current which adjusts the laser power is supplied from a constant current circuit 2 to another laser driver 3 to optimize the color balance of a color image.
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