| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device capable of more definitely, and more efficiently performing appropriate density control corresponding to various originals with the different density condition, etc., by providing the image density controlling means equipped with plural controlling means, and selecting control system of image density controlling means, based on the original density information. SOLUTION: Based on the control sequence of ROM 14, the original reading (scanning) operation is started after a lamp 5 is turned on, photometric value is averaged (10msec unit for instance), from a light receiving sensor 10 stored in RAM 13 within a specific time, and the average value (original density information) is compared with the predetermined threshold. At this time, if the average value becomes equal to or above the threshold (when original density is comparatively dark), 'real time controlling system' is selected as the controlling system of the transferring bias output circuit 17 for the developing bias circuit 16, in predicting the presence of low density image part in the original center part, etc., and on the contrary, if the average value becomes smaller than the threshold, 'hold controlling system' is selected as the controlling system. |
