Image forming apparatus with developing device, sensor, and controller

摘要

An image forming apparatus includes an image bearing member, a developing device for developing an electrostatic latent image including a developer and a developer carrying member, a sensor for detecting information related to a toner charge amount of the developer, and a controller. An image forming period has a first period and a second period, during which different modes are executed by the controller to provide for a lower speed of the developer carrying member in the first period than in the second period. The controller is capable of executing an operation that lowers the potential difference between a non-image-forming portion of the image bearing member and the developing bias applied to the developer carrying member based on detection results of the sensor.

主权项

1. An image forming apparatus comprising:
an image bearing member; a developing device for developing an electrostatic latent image formed on a surface of said image bearing member, wherein said developing device includes a developer carrying member for carrying a developer including a non-magnetic toner and a magnetic carrier and for conveying the developer to a developing position in which the developer carrying member opposes said image bearing member; a sensor for detecting first information relating to a toner charge amount of the developer in said developing device; and a controller; wherein an image forming period includes a first period in which an area, corresponding to a recording material, of a surface of said image bearing member passes through the developing position, and a second period in which an area, which does not correspond to the recording material, of the surface of said image bearing member passes through the developing position, wherein during a continuous image forming job, said controller effects, on the basis of second information relating to a conveyance interval between the recording material subjected to image formation and a subsequently-conveyed recording material, control so that a driving speed of the developer carrying member in the second period is lower than a driving speed of the developer carrying member in the first period or so that drive of the developer carrying member in the second period is stopped, and wherein said controller effects, on the basis of the first information and the second information, control so that a potential difference between a non-image-portion potential of said image bearing member and a developing bias applied to said developer carrying member is lower in the second period than in the first period.