| 摘要 |
PURPOSE:To prevent a ground stain and to easily execute an image adjustment by adjusting the supply voltage of an original lamp in accordance with the degree of fatigue of a photosensitive body, and correcting automatically a developing bias potential, when the supply voltage reaches a prescribed value. CONSTITUTION:Even when the supply voltage of an original lamp of F5 is 69V at the time point of copying of 20,000 sheets, a bright part potential VL value becomes -200V. In such case, when a user adjusts an F5 shift key 10 again, an adjusting means, first of all, raises the original lamp supply voltage to 69V of a prescribed value by a lamp regulator 13, and switches it automatically to a developing bias DC portion by a microcomputer 15. That is to say, it is switched to a high voltage transformer 27 side being a correcting means for correcting a developing bias potential. Accordingly, the original lamp supply voltage becomes 69V of the upper limit, and -250V adding -30V to -220V of the initial developing bias DC portion is applied to a developing sleeve 32. In such way, a correct image being free from fog is obtained. |
