Image forming apparatus capable of changing the surface potential of a photosensitive member.

摘要

An image forming apparatus is provided with a photosensitive member; a charger including a corona ion generator and a grid electrode provided between the photosensitive member and the corona ion generator, and adapted for charging the surface of the photosensitive member while regulating the surface potential of the photosensitive member by the grid electrode; a current supply circuit connected to the charger and capable of supplying to the charger a first current not lower than a specified level for charging the surface of the photosensitive member at a first voltage at which an image of high contrast can be formed and a second current lower than the specified level for charging the surface of the photosensitive member at a second voltage at which an image having an intermediate gradation thereof emphasized is formed, the second voltage being lower than the first voltage; and a current switch circuit for switching the level of the current to be supplied to the charger means according to needs. Accordingly, a circuit construction of the charger can be simplified and the number of components thereof can be reduced, with the result that the price of the apparatus itself can be reduced.