Canon Kabushiki Kaisha

Kazuhiro Okubo

Jun Miura

Masanori Tanaka

Takahiro Kawamoto

Yuji Kawaguchi

Motoki Adachi

Masaki Ojima

Masahide Kinoshita

Masao Uyama

Masahiro Shibata

Masahiro Yoshida

Hisashi Yamauchi

Kazunori Hashimoto

Takaaki Shinkawa

Takashi Mukai

Yoshihiro Ito

Masanobu Saito

Ryo Sugiyama

Minoru Matsuguma

Mitsuru Okuda

Kazuhisa Maruyama

Yoshinobu Ogawa

Jun Haruna

An image forming apparatus includes an image bearing member, a charging member, an exposure unit which performs first exposure to form a non-image portion potential on the electrically charged surface of the image bearing member, and second exposure to form an image portion potential thereon, a developing member, a charging voltage application unit, a current detection unit which detects a current flowing from the image bearing member to the charging member, and a control unit which controls the exposure unit and the charging voltage application unit, wherein, in a case where a current value detected in a predetermined charging voltage application state is a second current value larger than a first current value, the control unit controls the exposure unit to perform image formation with a first exposure amount smaller than that in a case where the detected current value is the first current value.

Image forming apparatus

An image forming apparatus using a contact charging method includes a control unit capable of executing cleaning in a post-rotation step at the end of a job and in an inter-image step during execution of the job. The cleaning involves moving toner adhering to a charging member from the charging member to an image bearing member. The job is a series of operations started by a predetermined start instruction and involving forming an image on one or more recording materials and outputting the one or more recording materials. When an instruction to start the next job is input during execution of cleaning in the post-rotation step, the control unit stops the cleaning in the middle of the execution, starts the next job, and adjusts timing for executing subsequent cleaning on the basis of information relating to the amount of cleaning executed before being stopped in the middle of the execution.

In an image forming operation of transferring one developer image to a recording material, when a plurality of image forming portions include a non-image forming portion that is an image forming portion which does not form a developer image on an image bearing member, applying means for applying a charging bias to a charging member which comes into contact with and charges the image bearing member applies a second charging bias to the charging member in the non-image forming portion, the second charging bias having a same polarity as a first charging bias for forming a developer image and being a voltage equal to or lower than a discharge start voltage.

In an image forming apparatus which includes a plurality of image forming units each including an image bearing member, a contact charging member, and a developer bearing member for forming toner of normal polarity, and which, in a printing operation, applies a charging bias having a first direction, in a cleaning operation, applies a charging bias having a second direction, and recovers residual toner remaining on the image bearing member which was not used for printing by the developer bearing member, before performing the cleaning operation, when successively performing the printing operation on a plurality of recording materials including a first recording material and a second recording material, which is used for printing following the first recording material, the charging voltage larger in absolute value in the printing operation for the second recording material than in the printing operation for the first recording material is applied.

Image forming apparatus having recovery of toner by developing member, control of charging voltage and charging member cleaning operation

An image forming apparatus includes image forming units each of which includes an image bearing member, a contact charging member, and a developer bearing member of a toner, applies a charging bias in a direction in which the toner moves from the image bearing member to the charging member in an image forming period, and applied a charging bias of an opposite polarity relative to that in the image formation in a cleaning period, and collects the toner by the developer bearing member. In consecutive image formation, a charging bias in the image forming period is applied in a first interval period and which is between first and second image forming periods and a second interval period which is between second and third image forming periods. An absolute value of a charging bias applied in the second interval period is larger than that applied in the first interval period.

In an image forming apparatus, a control unit performs a control to cause an exposing unit to expose a plurality of image bearing members at different times to form exposure regions on the plurality of image bearing members, to acquire results acquired by applying direct current voltage lower than discharge start voltage to a plurality of abutting members by an applying unit when the exposure regions pass by abutting parts against the abutting members and detected by a detecting unit, and to, based on the acquired results of the detections, acquire information regarding the surface potentials of the plurality of image bearing members.

Image forming apparatus to acquire image bearing member surface potentials

A developer carrying member is disposed below a storage chamber of a frame and has a surface configured such that a plurality of dielectric portions are dispersed on a conductive portion, an upper region of the storage chamber of the frame is enlarged further in a horizontal direction than a lower region in which the developer carrying member is disposed, and the frame has a lower guide surface and includes a curved surface having a tangent plane inclined at a first angle equal to or greater than a degree of an angle of repose of the developer and less than 90 degrees, in an inner wall of the lower region, and an upper guide surface includes a curved surface having a tangent plane inclined at a second angle that is less than the first angle relative to a horizontal plane in an inner wall of the upper region.

Developing apparatus having a large capacity toner storage chamber, and image forming apparatus

An image forming apparatus using a contact charging method includes a control unit capable of executing cleaning in a post-rotation step at the end of a job and in an inter-image step during execution of the job. The cleaning involves moving toner adhering to a charging member from the charging member to an image bearing member. The job is a series of operations started by a predetermined start instruction and involving forming an image on one or more recording materials and outputting the one or more recording materials. When an instruction to start the next job is input during execution of cleaning in the post-rotation step, the control unit stops the cleaning in the middle of the execution, starts the next job, and adjusts timing for executing subsequent cleaning on the basis of information. relating to the amount of cleaning executed before being stopped in the middle of the execution.

A control unit of an image forming apparatus controls, in an image forming mode, a potential difference obtained by subtracting the voltage applied to the developer bearing member from the voltage applied to the regulating member so that the potential difference is set to the polarity of the developer, and the control unit controls, in a lubricant discharge mode, the potential difference obtained by subtracting the voltage applied to the developer bearing member from the voltage applied to the regulating member so that the potential difference is set to the polarity of the lubricant or '0'.

A developing apparatus includes a developer carrying member, a developing frame member to rotatably supporting the developer carrying member, and a regulating member provided on the developing frame member and regulating developer carried on the developer carrying member. The regulating member includes a projecting part projected towards the developer carrying member and having an abutting part that abuts the developer carrying member, and an opposing surface facing the developer carrying member. The opposing surface is positioned on an upstream side of the projecting part and arranged to connect the projecting part with a distal end of the regulating member at a free end side of the regulating member. In addition, the opposing surface is a surface having no point of reverse curve, and the distance between the opposing surface and the developer carrying member is constant or decreasing with distance from the projecting part.

Developing apparatus having a projecting regulating member and process cartridge

An image forming apparatus in which an image is formed on a recording material includes an exposure unit that forms a non-image section potential through exposure of a photoconductor at a first laser power and forms an image section potential through exposure of the photoconductor at a second laser power that is greater than the first laser power. A control unit controls an output of laser power of the exposure unit. The output of the first laser power is controlled during formation of the non-image section potential, so as to be of a first intensity at the middle of an image forming region of the recording material, and to be of a second intensity, stronger than the first intensity, at end sections of the image forming region.

An image forming apparatus includes first and second developer carrying members and a control device. The apparatus is operable in a first mode where an image of a single color is formed using the first developer carrying member and is operable in a second mode, wherein an image of a plurality of colors is formed using the first and second developer carrying members. The control device controls a first discharging operation for discharging developer from the first developer carrying member and a second discharging operation for discharging developer from each of the first and second developer carrying members. When the apparatus executes only the first mode, the control device performs more image formations, in a period between completion of the second discharging operation and start of the first discharging operation, compared to a period between completion of the first discharging operation and start of a subsequent first discharging operation.

Image forming apparatus featuring a control device for controlling a developer discharge operation in first and second modes

An image forming apparatus includes a toner carrying member for supplying toner to an image bearing member to visualize the latent image; a rotatable toner supply member, contacted to the toner carrying member, for supplying toner to the image bearing member; a voltage applying device for applying voltages to the toner carrying member and the toner supply member; and a controller for controlling the voltage applying device to control voltages applied to the toner carrying member and the toner supplying member.

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Kawasaki, Japan

Kazuhiro Okubo