Patent ID: 8121499
Filing Date: 2012-02-21
Classification: G03G

Abstract:
1. An image forming apparatus comprising: an image bearing member; a latent image forming device for forming a latent image on said image bearing member in accordance with image information; a developing device for developing the latent image with a developer, carried on a developer carrying member, including toner and carrier; a supplying device for supplying the toner to said developing device; a potential controller for controlling a potential difference between a DC bias voltage applied to the developer carrying member and an image portion potential of said image bearing member, wherein said potential controller controls the potential difference so that the potential difference is smaller in a patch image formation than in a normal image formation; an image density sensor for detecting an image density of the patch image; a first controller for correcting an amount of supply from said supplying device on the basis of a detection result of said image density sensor; a density sensor for detecting a toner content of the developer accommodated in said developing device; a second controller for limiting the amount of the supply from said supplying device or forcing the supply irrespective of an output of said image density sensor, when an output of said density sensor is outside a predetermined range; a first correcting device for correcting a development contrast when the patch image is formed when the output of said density sensor is outside the predetermined range; and a second correcting device for correcting a development contrast for the normal image formation in accordance with an amount of correction, by said first correcting device, of the development contrast for a patch image formation, wherein said second correcting device corrects the development contrast for the normal image formation so as to satisfy: where VcontP VcontP VcontG VcontG