Canon Kabushiki Kaisha

Takuya Hori

Shinya Suzuki

Tadashi Fukuda

Dai Kanai

Naoki Mugita

A developing device includes an accommodating casing, a rotatable developer carrying member, a regulating portion, a magnetic flux generating portion including a first magnetic pole and a second magnetic pole which have the same polarity, and a cover portion provided downstream of the developing region and upstream of a maximum magnetic flux density position of the second magnetic pole with respect to a rotational direction of the developer carrying member. The cover portion is disposed between the casing and the developer carrying member. As measured in the rotational axis direction, a dimension of the cover portion at an upstream end with respect to the rotational direction is smaller than a dimension of the cover portion in at least a region positioned downstream of the upstream end with respect to the rotational direction.

Developing device

An opposing surface of a partition opposing a first conveyance screw includes an arc-shaped guide portion for guiding conveyance of developer at least on an upstream side in a first conveyance direction of the first conveyance screw. The guide portion is extended from a bottom portion of a first chamber opposing the first conveyance screw and formed along an outer periphery of the first conveyance screw. As seen in a cross section orthogonal to a rotation axis of the first conveyance screw, the opposing surface of the partition within a predetermined area includes the guide portion over an angle of 30% or more of the predetermined area in a direction of rotation of the first conveyance screw.

An image forming apparatus is disclosed. The image forming apparatus includes an image bearing member, a developing device, a gap retaining member and a control unit. The control unit decreases a potential difference according to an increase in the drive amounts of the image bearing member and the developer bearing member. The decrease is based on a difference according to an increase in at least one of the drive amounts of the image bearing member and the developer bearing member. The control unit is also configured to determine whether to execute a mode based on information about at least one of the driving amounts of the image bearing member and the developer bearing member from when the developing device is initially installed or the developing device is replaced.

Image forming apparatus having controllable potential difference

An image forming apparatus includes an image forming portion for forming an image on a recording material, a sensor to detect a toner image formed by the image forming portion, and a correcting portion to correct an image forming condition of the image forming portion on the basis of a result of detection, by the sensor, of a first control toner image formed by the image forming portion. In addition, a supply controller controls a developer supplying operation on the basis of a result of detection, by the sensor, of a second control toner image formed by the image forming portion. A controller controls an image forming condition such that the first control toner image is formed at the image forming speed of a second image forming mode, and the second control toner image is formed after the image forming speed is changed to a third image forming speed which is higher than the second image forming speed.

Growing community of inventors

Kashiwa, Japan

Takuya Hori