| 摘要 |
PURPOSE:To prevent generation of uneven density as against the contamination of a wire in controlling image forming conditions by controlling the intensity of the primary electrostatic charge current and the secondary electrostatic charge current by setting upper limit values for both and setting a lower limit value for either one thereof. CONSTITUTION:An original exposure lamp 11 or blank exposure lamp 6 is turned ON/ OFF to form a bright part potential VSL and the dark part potential VD by putting out of the lamp on a photosensitive drum 1. A latent image potential is detected with a potential sensor 7, and is converted to a prescribed level in a potential measuring circuit 18. The surface potential converted to a digital quantity thereafter outputs control data so as to attain the value near the target respectively in an MPC 15. When the value of secondary current I2 decreases lower than a preset limit value I2 low, said value is converted to an analog quantity. The analog quantity is inputted to control circuits 18, 19 for primary and secondary high voltages, by which a primary high voltage transformer 21 is controlled, and the quantity of electrostatic charge of a primary electrostatic charger 2 is controlled. The quantity of electrostatic charge of a secondary electrostatic charger 3 is also controlled, whereby the quantities of electrostatic charge are regulated so as to approach to their respective target values. |
