Canon Kabushiki Kaisha

Kyosuke Takahashi

Atsushi Matsumoto

Akihiro Noguchi

Katsuya Nose

Masanori Akita

Mitsuhiro Furukawa

Hideki Fujita

Kosuke Takeuchi

An image forming apparatus includes an image bearing member, a developing device, first and second drive portions, and a controller. The developing device includes first, second, and third conveying screws, and a developer bearing member. A ratio of a rotational driving speed (Vsc) of the first and second conveying screws by the first drive portion to a rotational driving speed (Vs1) of the developer bearing member by the second drive portion is Vsc/Vs1. A ratio of a rotational driving speed (Vsc3) of the third conveying screw by the second drive portion to the developer bearing member rotational driving speed (Vs1) is Vsc3/Vs1. In a control mode, the controller controls the first and second drive portions so that Vsc/Vs1 in a non-image forming period becomes less than Vsc/Vs1 in an image forming period such that Vsc3/Vs1 in the non-image forming period is equal to Vsc3/Vs1 in the image forming period.

Image forming apparatus

A change of a magnetic flux density distribution adjacent to a regulating bladeopposed to a developer regulation pole is suppressed at a low cost, while suppressing influence to design latitude of magnetic poles. A position on the outer peripheral surface of the developing sleeve where the magnetic flux density in the normal line direction of the outer peripheral surface of the developing sleeve is a maximum value position. The position on the outer peripheral surface of the developing sleevecorresponding to a center portion position of the half peak range of the magnetic flux density distribution of the developer regulation pole is called half peak center portion. The developer regulation pole is formed such that the maximum value position is deviated not less than 3&#xb0; in the circumferential direction of the developing sleeve from the half peak center portion position, and the position when the regulating bladeopposite is the developing sleeve is in a side of the maximum value position in which the half peak center portion position exists.

Developing apparatus

An image forming apparatus includes a controller to control a driving device such that a rotational speed of a supplying and feeding screw when it is rotated a predetermined number of times to supply developer to a developing device in a predetermined amount during execution of a continuous image forming job on a plurality of first recording materials is a first rotational speed, and a rotational speed of the supplying and feeding screw when it is rotated the predetermined number of times to supply the developer in the predetermined amount during execution of a continuous image forming job on a plurality of second recording materials is a second rotational speed slower than the first rotational speed. The second recording materials have a length longer than the first recording materials with respect to a sub-scan direction.

A developing apparatus includes a developing container accommodating a developer, a developing sleeve having a plurality of magnetic poles arranged in a circumferential direction, and a regulating member configured to regulate a layer thickness of the developer carried on the developing sleeve. The magnetic poles include a regulation pole disposed opposed to the regulating member such that a maximum value position at which a magnetic flux density in a normal line direction of the developing sleeve is a maximum is not less than 3&#xb0; away in a circumferential direction of the developing sleeve from a half peak center portion position which is a center portion position of a half-peak width of the magnetic flux density. The regulating member is disposed downstream of the half peak center portion position and upstream of the maximum value position with respect to a rotational direction of the developing sleeve.

An image forming apparatus includes an image forming portion configured to form an image on a recording media and including a developer bearing member configured to bear developer and carry the developer, a regulating portion disposed opposite to the developer bearing member and configured to regulate an amount of the developer on the developer bearing member, a first chamber configured to supply the developer to the developer bearing member, and a second chamber configured to communicate with the first chamber to form a circulating route of the developer. In addition, a first feeding member feeds the developer in the first chamber, and a second feeding member feeds the developer in the second chamber. A control portion executes, in a non-image forming state, a mode of driving the developer bearing member in a condition in which the first feeding member is stopped.

Developing apparatus having developer distribution control

An image forming apparatus includes an image bearing member, a developing device, a supplying device, and a control unit. The image bearing member bears a latent image. The developing device develops the latent image with a toner. The supplying device supplies toner to the developing device. The control unit executes a discharge operation to consume toner transferred onto the image bearing member from the developing device without transferring the toner onto a recording medium. The control unit executes the discharge operation where first deterioration integrated information exceeds a first executing threshold, and where second deterioration integrated information exceeds a second executing threshold that is larger than the first executing threshold. The control unit acquires the first deterioration information based at least a first deterioration threshold, and acquires the second deterioration information based on at least a second deterioration threshold that is larger than the first deterioration threshold.

Image forming apparatus with toner discharge operation

A developing device includes a developing container accommodating a developer including toner and magnetic particles, a developer carrying member rotatably provided opposed to an opening of the developing container, a stirring member configured to stir the developer in the developing container to supply the developer to the developer carrying member, a first driving device configured to drive the developer carrying member, and a second driving device configured to drive the stirring member. A controller controls drive of the first driving device and the second driving device so that in a period from output of either earlier one of a stop signal of the first driving device and a stop signal of the second driving device to rotational speeds of both of the developer carrying member and the stirring member becoming not more than &#xbd; of rotational speeds in a steady state during image formation.

Developing device and image forming apparatus having developer carrying and stirring control

An image forming apparatus includes an image forming portion having a first feeding member to feed developer in a first chamber, a second feeding member to feed the developer in a second chamber; and a control portion to execute a plurality of modes by suspending image forming. A first mode circulates the developer in a condition in which a ratio of a rotational speed of the developer bearing member to a rotational speed of the first and second feeding members is decreased as compared to that in forming the images; and a second mode increases the ratio of the rotational speed of the developer bearing member to the rotational speed of the first feeding member as compared to that in forming the images. The second mode is executed after the first mode and before resuming the image forming operation.

An image forming apparatus that continuously carries out image formation on a plurality of recording materials includes an image bearing member and a developing device configured to develop an electrostatic latent image on the image bearing member. A first feeding screw is provided in a developing chamber and includes a first screw portion, a second screw portion and a third screw portion. Each of the second and third screw portions are provided with a blade portion formed helically on an outer peripheral surface of a rotation shaft of the first feeding screw, and the first screw portion is not provided with the blade portion. Based on information on the relative humidity in the developing container and on the amount of toner consumed with the image formation on a plurality of recording materials, a controller controls a driving speed for rotationally driving the first feeding screw by a driving device.

A developing device includes a developer carrying member for carrying a developer; a circulation path along which the developer is circulated; a carrier supplying portion; a discharge opening, provided in the circulation path, through which a portion of the developer is to be overflowed and discharged; and a feeding member comprising a rotation shaft and a blade portion including a helical portion. An outer diameter of the blade portion formed in a first region including at least a portion opposing the discharge opening is smaller than that in a second region adjacent to the first region with respect to a rotation shaft direction. A smaller average angle formed between the rotation shaft and a developer feeding surface of the blade portion in the first region is smaller than that in the second region.

Developing device having rotating feeding member

A developing device includes a developer carrying member, a first chamber for feeding developer to the developer carrying member, a second chamber for collecting developer from the developer carrying member, and a feeding member provided rotatably in the first chamber for feeding the developer. The feeding member includes a rotation shaft and a spiral blade wound helically in a developer feeding direction. The feeding member includes a first region corresponding to a developer coating region of the developer carrying member, a second region provided downstream of the first region with respect to a feeding direction of the feeding member, and a third region provided upstream of the first region. An average feeding power per unit driving time of the feeding member is set at a smaller value in the first region than in the second region and in the third region.

Developing device

An image forming apparatus includes an image bearing member on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image formed on the image bearing member by using developer, a temperature detecting portion that detects information regarding the temperature of the developer in the developing device, and a density detecting portion that detects the density of a control image formed on the image bearing member. In addition, a controller controls the amount of the developer supplied to the developing device based on the detection result of the density of the control image, and a change portion changes an electric potential difference between an electric potential of the electrostatic latent image of the control image and a DC bias applied to the developing device so as to compensate for changing developing efficiency caused by temperature, based on the detection result acquired by the temperature detecting portion.

A developing device includes a developer carrying member for carrying a developer; a first feeding portion for supplying the developer to the developer carrying member while feeding the developer along the developer carrying member; a second feeding portion, communicating with the first feeding portion at end portions thereof, for feeding the developer in a direction opposite to a developer feeding direction of the first feeding portion while collecting the developer from the developer carrying member; and a partition wall portion for partitioning the first and second feeding portions. The partition wall portion includes an opposing portion opposing the developer carrying member with a spacing. A surface roughness of at least the opposing portion is larger than that of the developer carrying member.

Growing community of inventors

Toride, Japan

Kyosuke Takahashi