| 摘要 |
PURPOSE: To provide a method for detecting the life of a contact electrostatic charging member capable of preventing the occurrence of leakage by detecting the life of the electrostatic charging member with higher accuracy. CONSTITUTION: This image forming device has at least a photosensitive drum (image carrying member) 1, an electrostatic charging roller (contact electrostatic charging member) 2 which comes into contact with the surface of the photosensitive drum 1 and a high-voltage power source 3 which uniformly electrostatically charges the surface of the photosensitive drum 1 by impressing a bias to the electrostatic charging roller 2. The surface of the electrostatic charging roller 2 is provided with plural current detecting members 4a, 4b, 4c which are divided in the longitudinal direction of the roller and come into contact with its surface. Judgment is made that the life of the electrostatic charging roller 2 runs out when the max. current value Imax among the current values detected by these current detecting members 4a, 4b, 4c attains the predetermined upper limit value of the prescribed current or above. The film thickness of the surface layer is detected by the current values at the plural points in the longitudinal direction of the electrostatic charging roller 2. The current value (max. current value Imax) of the part where the thickness is smallest and the predetermined upper limit value of the current are compared, by which the life of the electrostatic charging roller 2 is detected with the high accuracy and the occurrence of the leakage is prevented. |
