Patent ID: 7283756

Claim:
An image forming apparatus comprising: an image bearing member on which an electrostatic image is formed; developing means comprising a developing container which contains developer comprising a carrier and a toner, a developer carrying member which is provided at an opening portion of the developing container and which carries the developer, and a developer conveying member which is disposed inside the developing container and which carries developer in the vicinity of the developer carrying member in a longitudinal direction of the developer carrying member, the developing means developing the electrostatic image on the image bearing member; wherein, the developing container comprises a first chamber having the opening portion and in which the developer conveying member is disposed, and a second chamber for returning developer that was carried from the first chamber; control image formation means that forms an image for image density control comprising the toner on the image bearing member; image density detection means that detects at a predetermined detection position a density of the image for image density control on the image bearing member or on a transferring medium to which an image on the image bearing member is transferred; and image density control means that performs image density control based on a detection result from the image density detection means, wherein, when a developer amount per 10 mm in the longitudinal direction of the developer carrying member inside the first chamber is taken as Y (g), a developer carrying velocity in the longitudinal direction of the developer carrying member inside the first chamber is taken as V D (mm/sec), a toner carrying amount per unit area on the image bearing member at the time of formation of a maximum density image is taken as M (mg/cm 2 ), a surface movement velocity of the image bearing member is taken as V p (mm/sec), and the distance from a position furthest downstream in a direction in which developer is conveyed by the developer conveying member in a maximum area in which development is possible on the developer carrying member to the predetermined detection position in the longitudinal direction of the developer carrying member is taken as X (mm), the following relation is satisfied: X ≦(45× Y×V D )/( M×V p ).