Reverse developing image forming apparatus with small drum

An image forming apparatus comprising:

• storing means for storing a sheet-like medium of a predetermined length;
• a photosensitive drum having a circumferential length shorter than said predetermined length;
• charging means for uniformly electrostatically charging the photosensitive drum and any residual toner on said photosensitive drum;
• exposure means for selectively exposing the electrostatically charged photosensitive drum and said residual toner in accordance with data representative of an image, thereby forming an electrostatic latent image corresponding to said image on the photosensitive drum;
• reverse developing means having a developing electrode for developing the latent image with toner, said developing means being provided adjacent to the surface of said photosensitive drum for causing particles of said toner charged in the same polarity as the electrostatic latent image to adhere to said photosensitive drum so as to form a toner image corresponding to the latet image on said photosensitive drum and for causing particles of said residual toner on non-image portions of said photosensitive drum which have been charged by said charging means and exposed by said exposure means to be attracted to said developing means to thereby simultaneously develop said latent image and clean said residual toner from said photosensitive drum;
• and
• transfer means for transferring said toner image from said photosensitive drum to the sheet-like medium.