Canon Kabushiki Kaisha

Masahiro Ootsuka

Ryohei Terada

Ichiro Katsuie

Shoji Naruge

Osamu Ariizumi

Tatsuya Inoue

Shinya Suzuki

Hideaki Suzuki

Fumitake Hirobe

Yoshiro Tsukada

Takanori Iida

Shunsuke Tsuda

Mitsuhiro Furukawa

Fumiyoshi Saito

Shunichi Takada

Mitsuyoshi Arakawa

An image forming apparatus to execute an image forming operation for forming an image includes an image bearing member, a development unit, a drive unit, a controller, and a humidity detection unit to detect humidity near the development unit. The development unit contains developer and includes a conveyance member to convey the developer and a developer carrying member to carry the developer to a position where an electrostatic latent image formed on the image bearing member is developed. The controller controls the conveyance and the developer carrying member through the drive unit not to execute a mode for driving the conveyance and the developer carrying member without executing the image forming operation when the humidity detected when power of the image forming apparatus is shifted from off to on is higher than a predetermined value, and to execute the mode when the detected humidity falls below the predetermined value afterward.

Image forming apparatus that executes a mode for driving each of conveyance member and developer carrying member without executing image forming operation

A developing device includes a developer carrying member, a first chamber, a second chamber, a first communicating portion, a second communicating portion, and a feeding screw, provided in the second chamber, including a feeding portion having a first helical blade and including a returning portion having a second helical blade in the form of a plurality of threads, the feeding portion and the returning portion being provided so that a boundary portion therebetween opposes the second communicating portion. The first helical blade and the second helical blade satisfy the following relationship: P2&#x2265;P1, where P1 is a pitch, or lead, of the first helical blade and P2 is a lead of the second helical blade.

Developing device having a feeding screw with multiple blade portions

A developing device includes a rotatable developer carrying member enclosing a magnetic field generating portion including a plurality of magnetic poles and configured to carry a developer; and a resinous regulating portion provided at a position opposing the developer carrying member and configured to regulate an amount of the developer carried by the developer carrying member. The regulating portion is formed of a resin material containing magnetic powder, and at least a free end portion, opposed to the developer carrying member, of the regulating portion has relative permeability of 10 or more and 60 or less.

Developing device

An image forming apparatus including a toner container, a toner amount detection unit, a driving unit, a toner accommodating unit, a remaining toner amount detection unit, and a control unit is provided. The toner container supplies the toner to the toner accommodating unit by being rotated in a first direction. The toner amount detection unit detects a value related to an amount of the toner in the toner container. The control unit controls the driving unit so as to rotate the toner container in a second direction in a case where the remaining-toner amount detection unit has detected that the amount of the toner accommodated by the toner accommodating unit is smaller than a first set amount and the amount of the toner contained in the toner container detected by the toner amount detection unit reaches a second set amount.

Image forming apparatus

A development device wherein a magnetic force distribution of a developer bearing member in a longitudinal direction at positions at which a magnetic flux density of a low magnetic field area is minimal in the peripheral direction of the developer bearing member is set such that a difference between a maximum magnetic flux density in a range from a maximum position at which an attenuation rate of the magnetic flux density is maximal to a 30 mm distant position toward the center of the developer bearing member and a magnetic flux density on a further center side of the developer bearing member than the range is 3 mT or less, and an absolute value of the magnetic flux density of a further outer side in the longitudinal direction of the developer bearing member than the maximum position is set to 3 mT or less.

Development apparatus and image forming apparatus

An image forming apparatus includes an image bearing member for bearing a latent image; a developing device, including a developer carrying member for carrying and feeding a developer including toner and a carrier to a developing position in which the developer opposes the image bearing member, for developing the latent image formed on the image bearing member; a discharging portion for permitting discharge of an excessive developer present in the developing device by supplying the developer into the developing device; a feeding member for feeding the developer in the developing device; a controller for controlling a forced discharging operation for discharging the excessive developer from the discharging portion by changing a driving condition of at least one of the developer carrying member and the feeding member; and a detecting device for detecting information correlating to flowability of the developer in the developing device. The controller is capable of controlling the forced discharging operation on the basis of a detection result of the detecting device.

Image forming apparatus featuring forced discharging of excessive developer

The image forming apparatus includes a developing chamber an agitating chamber, a first conveying screw which is arranged in the developing chamber and coveys developer from one end to the other end of the first chamber, a second conveying screw which is arranged in the agitating chamber and conveys developer from one end to the other end of the second chamber, a developing sleeve which bears developer supplied from the developing chamber and conveys the developer to the agitating chamber via a developing area opposed to a photosensitive drum, motors, which drive the developing sleeve, the first conveying screw and the second conveying screw, and a controller which controls drive of the developing sleeve and the second conveying screw so that trigger timing of drive stopping of at least the second conveying screw is to be later than trigger timing of drive stopping of the developing sleeve.

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Tokyo, Japan

Masahiro Ootsuka