IMAGE FORMING DEVICE

PURPOSE:To save space, to reduce costs and to prevent base soiling and toner flying by detecting the density of a visible picture obtained by developing a latent image for a reference picture and correcting a developing electric field based on the detecting signal. CONSTITUTION:This image forming device is provided with a latent image forming means 12 forming a latent image for the reference picture on an image carrier 1, a reflected density detecting means 10 detecting the density of a visible picture obtained by developing the latent image formed by the latent image forming means, and a means correcting the developing electric field based on the detecting signal from the reflected density detecting means 10. The potential of an image part, which rises with the lapse of time such as the image forming frequency, is controlled so that a developing bias potential is increased based on the detected value of the reflected density of the latent image for the reference picture. Consequently, the potential difference between an exposing part and the developing bias is kept nearly constant, and excessive toner concentration can be prevented. Accordingly, base soiling and toner flying can be prevented, and moreover space and costs can be reduced.