Canon Kabushiki Kaisha

Koji Shigehiro

Yoshiro Tsukada

Shunsuke Tsuda

Ryohei Terada

An image forming apparatus includes a controller, a drive unit, a developer bearing member, a regulation blade, and a sheet member. During non-image forming, the controller executes a control mode for controlling the drive unit to rotatably drive the developer bearing member in a second direction opposite to a first direction, and then rotatably drive the developer bearing member in the first direction. A portion above a horizontal line passing through a tip of the regulation blade out of the sheet member is disposed in a moving path of a developer born by the developer bearing member when the drive unit rotatably drives the developer bearing member in the second direction in the control mode, and is not disposed in the moving path of the developer born by the developer bearing member when the drive unit rotatably drives the developer bearing member in the first direction during image forming.

Image forming apparatus having development apparatus including sheet member which is disposed below position on developer bearing member where developer bearing member is closest to image bearing member

A developing apparatus includes a replenishment conveyance screw portion to convey replenishment developer from a developer replenishment portion toward a first communication portion. First, second and third blade portions are formed in a spiral shape on an outer circumferential surface of a rotation shaft of the replenishment conveyance screw portion. A pitch of the first blade portion, a pitch of the second blade portion, and a pitch of the third blade portion are each larger than a pitch of a blade of a second conveyance screw portion, and the third blade portion is continuously formed in a region between a terminal end of the first blade portion and a starting end of the second blade portion.

Developing apparatus having multi-blade portion replenishment conveyance screw

A developing device includes a rotatable developer carrying member, a developer regulating member, and a cylindrical magnetic field generating member provided inside the developer carrying member and including a regulating magnetic pole provided opposed to the developer regulating member. A magnetic flux distribution provided by the regulating magnetic pole includes a first local maximum portion on a side upstream of a closest position between the magnetic field generating member and the developer regulating member, a second local maximum portion on a side downstream of the closest position, and a local minimum portion between the first local maximum portion and the second local maximum portion. A rectilinear line connecting the closest position and a center of the magnetic field generating member is positioned between the first local maximum portion and the second local maximum portion.

Developing device having magnetic flux density distribution

An image forming apparatus includes a controller to control a driving unit that rotates a developing rotary member. Rotation speed of the developing rotary member is controlled to become a first rotation speed in an image forming period. Rotation speed of the developing rotary member is decelerated from the first rotation speed in a first period of a non-image forming period so that the rotation speed becomes a second rotation speed lower than the first rotation speed, and rotation speed is decelerated from the second rotation speed in a second period subsequent to the first period of the non-image forming period so that the rotation of the developing rotary member is stopped. A deceleration amount per unit time of the developing rotary member in the first period is smaller than a deceleration amount per unit time of the developing rotary member in the second period.

Image forming apparatus

A developing apparatus includes a developer bearing member to bear developer containing toner and carrier to develop an electrostatic latent image formed on an image bearing member, a first chamber to supply developer to the developer bearing member, a second chamber to communicate with the first chamber to circulate developer, and a partition wall to separate the first and second chambers. An opening portion, through which an airflow from the second chamber toward the first chamber passes, is provided to the partition wall, and a length of the opening portion is equal to or longer than a length of a plurality of pitches of blades of a conveyance screw provided in the second chamber. A length, in the vertical direction, of the opening portion at a first position is longer than a length, in the vertical direction, of the opening portion at a second position.

Developing apparatus and image forming apparatus

A developing apparatus includes a developer bearing member, a first chamber to supply the developer to the developer bearing member, and a second chamber to collect the developer having passed through a developing region. A guiding portion is arranged on a partition portion that separates the first and second chambers. The guiding portion guides the developer from the developer bearing member to the second chamber, and is positioned overlapping a communicating portion between the first and second chambers. One end portion of the guiding portion is arranged above an upper end of the partition portion, and the other end portion of the guiding portion is arranged above a rotation axis of a conveyance screw in the second chamber and below an uppermost portion of the conveyance screw while leaving a clearance between the guiding portion and the conveyance screw.

Developing apparatus having developer guiding portions

A developing device includes a developer bearing member which bears a two-component developer including a toner and carrier, a magnet member disposed inside the developer bearing member, and a developer regulating member which regulates a layer thickness of the developer borne on the developer bearing member. The developer regulating member is made of magnetic material and is fixed at both end portions in a longitudinal direction. Grooves are formed on a surface of the developer bearing member, and a developer conveying force of the grooves at a central portion of the developer bearing member in the longitudinal direction is larger than a developer conveying force of the grooves at an end portion of the developer bearing member in the longitudinal direction.

Developing device and image forming apparatus

According to a representative configuration of the developing device and the image forming apparatus of the present invention, the developing device includes: a developing sleeve which bears developer and conveys the developer to a developing region; a developing chamber which supplies the developer to the developing sleeve; an agitating chamber which forms a circulation path with the developing chamber and collects the developer from the developing sleeve; and a conveying unit (a first conveying screw and a second conveying screw) which circulates and conveys the developer in the circulation path. A spiral groove is formed on a surface of the developing sleeve so as to apply a conveying force to the developer in a rotation axis direction of the developing sleeve opposite to a developer conveying direction of the agitating chamber.

A temperature sensor detects information regarding humidity in an atmosphere of a developing container. A temperature sensor detects information regarding humidity in an atmosphere of a toner hopper. An inductance sensor detects information regarding a toner density within the developing container. A printer controller controls a replenishing operation of a replenishing screw member based on image information. The printer controller controls the replenishing operation of the replenishing screw member so that a toner density within the developing container is less than or equal to a predetermined value based on a detection result of the inductance sensor. The printer controller controls the predetermined value to be small when a difference between humidity detection results detected by each of the temperature sensors is large as compared to when the difference is small.

A developing device includes a developing container in which a developer is contained; a developer carrying member for carrying the developer and feeding the developer by rotation thereof to a developing zone in which the developer carrying member opposes an image bearing member on which a latent image is formed and develops the latent image with the developer; and an electrode, disposed opposed to the developer carrying member, to which a bias for forming an electric field for moving regular-charge toner in the developer container toward the developer carrying member is to be applied. The electrode is provided downstream of the developing zone with respect to a rotational direction of the developer carrying member and is provided vertically above the developer carrying member. At least a part of the electrode is located downstream of a rectilinear line connecting a rotation center and top point of the developer carrying member with respect to the rotational direction of the developer carrying member.

Developing device

An aspect of the invention provides a development device including a rotatable development sleeve which supplies developer to a photosensitive drum, the development sleeve being disposed such that a rotational axis of the development sleeve is orientated toward a vertical direction; a conveying screw which conveys the developer along a rotational axis direction of the development sleeve; and a developer supply guide which guides the developer conveyed by the developer conveying device to the development sleeve. The plural developer supply guides are disposed at predetermined intervals in the rotational axis direction of the development sleeve and between the development sleeve and the conveying screw.

Development device and image forming apparatus

An image forming apparatus includes an exposure device for exposing an electrically charged surface of an image bearing member to light to form an electrostatic image; a developing device capable of collecting a transfer residual developer remaining on the image bearing member; a transferring device for transferring a developer image from the image bearing member onto a transfer medium at a transfer position; and a controller for executing, during non-image formation, a developer collecting mode in which a developer of an opposite polarity is collected into the developing device by driving the image bearing member and by causing the developer carrying member to stop its rotation or rotate at a speed slower than a rotational speed thereof during image formation while generating a potential difference capable of transferring the developer of the opposite polarity from the image bearing member onto the developer carrying member.

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Toride, Japan

Koji Shigehiro