Abstract: The content of processing of an input image signal varies depending upon the conditions of an apparatus. In view of the fact that this results in the variations of correlation between tone data and toner consumption, a coefficient by which an integration value of the tone data is defined according to the content of the signal processing. In an image forming apparatus which performs tone correction as the signal processing and which has a characteristic (2) of forming images of higher densities relative to tone levels, for example, a larger amount of toner is consumed. Therefore, the coefficient of the apparatus is defined to be a higher value than that of an apparatus having a substantially linear characteristic (1). Conversely, in the case of an apparatus having a characteristic (3) of forming images of lower densities, thus consuming less toner, the coefficient is defined to be a lower value.

Abstract: The surface of a photosensitive body is charged by a scorotron charger including a discharge electrode, a back plate having an aperture on the bottom face, and a grid. Air is passed along the back plate for ventilation. The back plate also has a vent aperture on the side face. The aperture rate of the aperture on the bottom face of the part corresponding to the vent aperture is set lower than that on the bottom face of the other part, in the axial direction of the charger.

Abstract: An image forming apparatus having a charger of a non-contact type opposed to a photosensitive body coated with a photosensitive layer by dipping for charging a surface of the photosensitive body and an interval between the surface of the photosensitive body and the charger is narrowed on a dip upper portion side of the photosensitive body and widened on a dip lower portion side thereof. When the charger is a scorotron charger having a discharge electrode and a grid, an interval between the grid and the surface of the photosensitive body is narrowed on the dip upper portion side of the photosensitive body and widened on the dip lower portion side.