Canon Kabushiki Kaisha

Canon Finetech Nisca Inc.

Masashi Wakisaka

Yusuke Ishida

Katsuya Nose

Takanori Iida

Yuta Okuyama

Chihiro Tanaka

Tomoyuki Sakamaki

Osamu Ariizumi

Hideki Fujita

Ryo Nakajima

Hideo Nagura

Naoki Tamaru

Masashi Abe

Tsuyoshi Takahashi

A developing device includes a developer bearing member, a developing container which accommodates developer, a conveying screw which conveys the developer accommodated in the developing container, and an inductance sensor which includes a detecting portion which detects magnetic permeability of the developer accommodated in the developing container. The conveying screw includes a rotary shaft, a blade which is spirally formed on an outer circumference of the rotary shaft, and a rib formed to protrude outwardly from the outer circumference of the rotary shaft. The rib is disposed opposite the detection portion with respect to a conveying direction of the conveying screw and is provided with a magnet, with magnetic flux density of the magnet being in the range of 20 mT to 60 mT.

Developing device having inductance sensor

A developing apparatus includes a developing container to accommodate a developer and having first and second chambers divided by a partition wall for supplying the developer to a rotatable developing member and first and second communicating portions to allow the developer to move between first and second chambers by conveyance screws. A third communicating portion is disposed between the first and second communicating portions and above the conveyance screws to allow air inside the developing container to move between the first chamber and the second chamber. The developing container further includes a third chamber disposed above the second chamber in the vertical direction and accommodates initial developer in an unused state of the developing apparatus, and an opening portion for discharging the air inside the developing container to outside of the developing container is provided in the third chamber, with the opening being disposed above the third chamber.

Developing apparatus having air discharge

An image formation apparatus includes an image-bearing member, an exposure device, an electro-conductive member, a bias application unit and a development device having a development roller and a toner supply roller. The bias application unit configured to apply biases to the toner supply roller, the development roller, and the electro-conductive member during image formation so that a first potential difference between the toner supply roller and the development roller and a second potential difference between the electro-conductive member and the development roller cause normally charged toner to travel respectively from the toner supply roller and the electro-conductive member to the development roller, and a third potential difference between the electro-conductive member and the toner supply roller causes normally charged toner to travel from the electro-conductive member to the toner supply roller. The second potential difference is larger than the first potential difference and is larger than the third potential difference.

Image formation apparatus

An image forming apparatus includes a permeability sensor configured to detect information on magnetic permeability of developer contained in a developer container for detecting toner density of the developer, and a controller configured to control a control voltage applied to the permeability sensor so that (i) a value of the control voltage that is applied to the permeability sensor in a case where a predetermined condition including a condition that the toner density of the developer contained in the developer container is a predetermined density is satisfied and an amount of the developer contained in the developer container is a first amount is greater than (ii) a value of the control voltage applied to the permeability sensor in a case where the predetermined condition is satisfied and the amount of the developer contained in the developer container is a second amount greater than the first amount.

Image forming apparatus having toner density control

An image forming apparatus includes a control portion, and in a first period from when use of a developing apparatus is started until when an amount of developer in a developing device reaches a predetermined amount larger than an amount of initial developer, when an amount of developer supplied from a supplying portion through a single supplying operation in an image forming operation is larger than a predetermined supplied amount, the control portion interrupts the image forming operation and drives a conveyance portion for a predetermined time. In a second period after the amount of the developer reaches the predetermined amount, when an amount of the supplying developer supplied through a single supplying operation in the image forming operation is larger than the predetermined supplied amount, the control portion continues the image forming operation without interruption.

Image forming apparatus having image formation interruption

A developer conveying apparatus for conveying a developer that develops an electrostatic latent image includes a rotation unit which rotates around a rotation shaft extending in an axial direction and parallel to a developer conveying direction, a first developer conveying portion which is provided in the rotation unit and which has an opening configured to convey the developer in a first axial direction of the rotation shaft, and a second developer conveying portion which is provided in the rotation unit and which has an opening configured to convey the developer in a second axial direction opposite to the first axial direction. A distance from the rotation shaft to the opening in the first developer conveying portion is different than a distance from the rotation shaft to the opening in the second developer conveying portion.

Growing community of inventors

Misato, Japan

Masashi Wakisaka