Canon Kabushiki Kaisha

Osamu Ariizumi

Hideaki Suzuki

Shunsuke Tsuda

Teruaki Tsurusaki

Fumiyoshi Saito

Tomohiro Shiomi

Shunichi Koga

Masafumi Takahashi

Masahiro Ootsuka

Shinya Suzuki

Tomoyuki Sakamaki

Jun Mochizuki

Takanori Iida

Shota Soda

Hideki Fujita

Ryohei Terada

Jun Shirayanagi

Chihiro Tanaka

Masashi Wakisaka

Mitsuyoshi Arakawa

Ichiro Katsuie

Shoji Naruge

Masashi Abe

A developing device includes a first rotatable member having a rotation center Q and a second rotatable member having a rotation center R. When a rectilinear line connecting the rotation center Q and an intersection point X is a rectilinear line L, a rectilinear line connecting the rotation center Q and a magnetic flux density peak position Y is a rectilinear line L, a rectilinear line connecting the rotation center Q and a magnetic flux density peak position Z is a rectilinear line L, an acute angle formed between the rectilinear line Land the rectilinear line Lis α [°], and an acute angle formed between the rectilinear line Land the rectilinear line Lis β [°], α>β is satisfied.

Developing device

A developing device includes first and second chambers, a partition wall, first and second feeding screws, a developing roller, a supplying roller, a first magnet including a first magnetic pole, a second magnet including second to fourth magnetic poles, and a guiding portion. With respect to a supplying roller rotational direction, in a position downstream of the third magnetic pole, a magnetic flux density of the fourth magnetic pole in a normal direction is 20% of a maximum value thereof is a first position positioned downstream of a second position where a line connecting a lowermost end of the guiding portion and a supplying roller center crosses an outer peripheral surface of the supplying roller, and upstream of a third position where a line connecting an uppermost end of the first feeding screw and the supplying roller center crosses the outer peripheral surface of the supplying roller.

A developing device includes a rotatable developing member, a developing container, a first communication opening, a second communication opening, a first feeding screw including a first rotation shaft, first and second blade portions, a second feeding screw including a second rotation shaft, third and fourth blade portions, a developer discharge opening provided upstream of an upstream end of the second communication opening in a first direction, and a third communication opening provided upstream of the upstream end of the second communication opening in the first direction. In a second direction opposite to the first direction, the third communication opening overlaps with the second blade portion. In the first direction, the third communication opening overlaps with the fourth blade portion. In the first direction, a downstream end of the third communication opening is positioned downstream of a downstream end of the developer discharge opening.

A developing device includes a developer container configured to contain a developer, a developing carrying member configured to carry and feed the developer to a developing position, and a regulating member configured to regulate an amount of the developer carried by the developer carrying member, wherein the developer carrying member includes a magnet provided non-rotatably and stationarily inside the developer carrying member, and wherein the developer carrying member is provided with information regarding magnetic flux density of the magnet.

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

According to a first aspect of the present invention, a developing apparatus includes a developer container, a conveyance screw, and an inductance sensor. The conveyance screw further comprises a rib, protruding in a radial direction from the shaft portion, provided at a position opposed to the inductance sensor, and a second blade portion provided continuously to an upstream end portion of the rib with respect to the conveyance direction and configured to convey the developer to the conveyance direction by rotation. The second blade portion is formed to extend not more than one-third of a turn from the upstream end portion of the rib downstream in a direction of rotation of the conveyance screw when viewed in an axial direction of the conveyance screw.

Developing apparatus and conveyance screw

A target value for a gap between a developer bearing member supported by a developing frame member and a regulating blade that is fixed to the developing frame member is determined based on input information about a local maximum peak value of magnetic flux density of a predetermined magnetic pole which is located closest to the regulating blade when the regulating blade is fixed to the developing frame member among a plurality of magnetic poles included in a magnet fixedly located inside the developer bearing member and configured to generate a magnetic field for causing a developer to be borne by the developer bearing member.

Method for fixing regulating blade, developing device, developer bearing member, and magnet

A conveyance screw includes a shaft member, a first blade and a second blade each formed helically on a circumference of the shaft member. The first blade includes a first wide portion and a first narrow portion both located within an area in the axial direction where both of the first blade and the second blade are provided. The first wide portion is protruded radially outward from the shaft member to a first outer diameter. The first narrow portion is formed continuously with the first wide portion in a winding direction of the first blade around the shaft member, and is protruded radially outward from the shaft member to a second outer diameter that is smaller than the first outer diameter.

Conveyance screw and developing apparatus

A feeding screw for feeding a developer includes a rotation shaft, a first blade portion helically formed on an outer peripheral surface of the rotation shaft to feed the developer in one direction, a second blade portion helically formed on the outer peripheral surface to feed the developer in the one direction, and a third blade portion helically formed on the outer peripheral surface to feed the developer in the one direction. The first blade portion and the second blade portion overlap with each other with respect to a rotational axis direction of the feeding screw, the second blade portion and the third blade portion do not overlap with each other with respect to the rotational axis direction, and the third blade portion and the first blade portion overlap with each other with respect to the rotational axis direction.

Feeding screw and developing device

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 feeding screw for feeding a developer includes a rotation shaft, and first, second, and third blade portions helically formed on the outer peripheral surface of the rotation shaft to feed the developer in one direction. The first blade portion and the second blade portion overlap with each other, the second blade portion and the third blade portion do not overlap with each other, and the third blade portion and the first blade portion overlap with each other, all with respect to the rotational axis direction of the feeding screw. A gap is provided between a downstream end of the second blade and an upstream end of the third blade portion in the one direction, and the gap is disposed within a region where the first blade portion is formed with respect to the rotational axis direction of the feeding screw.

A developing device includes a first communication portion defining a communication path through which developer in a second chamber is communicated to a first chamber. The communication path has a first area and a second area. The first area is positioned within a range corresponding to a developer coating area of a developer bearing member in a conveyance direction of developer in the collection chamber, while the second area is positioned downstream of the developer coating area in the conveyance direction. A first length of the first area is shorter than a second length of the second area. The first length is a maximum length from a bottom surface portion of the communication path to an upper portion of the first area, and the second length is a maximum length from the bottom surface portion of the communication path to an upper portion of the second area.

A developing apparatus includes a rotatable developer bearing member, a first conveyance screw in a first chamber to convey the developer, and a second conveyance screw in a second chamber to convey the developer. The second conveyance screw includes a first screw portion facing a communication portion between the first and second chambers, a second screw portion downstream of the first screw portion, and a third screw portion downstream of the first screw portion and upstream of the second screw portion and facing the second communication portion. The first screw portion includes a first blade portion formed spirally around a rotation shaft of the second conveyance screw, the second screw portion has a second blade portion formed spirally around the rotation shaft of the second conveyance screw, and the third screw portion comprises no blade portion formed spirally around the rotation shaft of the second conveyance screw.

Development apparatus having a multiple screw portion conveyance screw

A developing apparatus includes a first screw disposed within a first chamber and conveying developer in a first direction, a second screw disposed within a second chamber and having a conveyance portion conveying the developer in a second direction opposite to the first direction and a return portion provided downstream of a first communication port in a first wall dividing the first and second chambers. A discharge portion in the second chamber, downstream of the return portion, discharges the developer out of the second chamber, and a second wall through which a third communication port is disposed upstream of the discharge portion is defined to deliver the developer from the second chamber to the first chamber. The second wall faces at least a part of the return portion in a view from a horizontal direction such that a lower end of the third communication port is located above a lower end of the first communication port.

Developing apparatus

An image forming apparatus includes first and second image forming portions. A first conveying pipe conveys a first developer discharged from a first developing unit to a collection portion, and a second conveying pipe conveys a second developer discharged from a second developing unit to the collection portion. A first detection unit detects a toner content of the first developer in the first conveying pipe, and a second detection unit detects a toner content of the second developer in the second conveying pipe. The first developing unit can be removed from the image forming apparatus in a state that the first conveying pipe and the first detection unit remain in the image forming apparatus, and the second developing unit can be removed from the image forming apparatus in a state that the second conveying pipe and the second detection unit remain in the image forming apparatus.

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Matsudo, Japan

Osamu Ariizumi