Abstract: An image forming apparatus which comprises a developing unit having a toner and a carrier therein, the apparatus includes an agitator to agitate the toner, a toner sensor to receive a control voltage and to generate an output voltage corresponding to a remaining amount of the toner in the developing unit, a pulse width modulator to supply the control voltage to the toner sensor corresponding to a pulse width modulation (PWM) signal and a controller to control the pulse width modulator to supply the control voltage to the toner sensor to adjust a duty ratio of the PWM signal and make the output voltage reach a target value. The controller determines whether the agitator is normal or abnormal based on the output voltage of the toner sensor.

Abstract: A developing device and an image forming apparatus including the same includes an agitating and conveying unit that receives a developer, and at least one agitating and conveying member to mix and agitate the developer and convey the developer in a developer conveying direction. A developing roller faces a photosensitive drum on which an electrostatic latent image is formed, and attaches the developer to an outer surface of the developing roller. The agitating and conveying member includes a support shaft extending in the developer conveying direction. A plurality of agitation wings disposed on an outer surface of the support shaft to mix and agitate the developer. At least one paddle protrudes from the support shaft in a radial direction and extends along the shaft between adjacent agitation wings. The at least one paddle has a height increasing from an upstream side to a downstream side of the developer conveying direction.

Abstract: A developing device includes: a developing container partitioned into a stirring-transport chamber, a supplying-transport chamber, and a collecting-transport chamber; a developer carrying member for carrying the developer on a surface thereof; a supplying-transport member located within the supplying-transport chamber; a stirring-transport member located within the stirring-transport chamber, for stirring and transporting the developer in a reverse direction to the supplying-transport member; a collecting-transport member located within the collecting-transport chamber, for stirring and transporting the developer in the same direction as the supplying-transport member; a first developer passage for passing the developer from the stirring-transport chamber to the supplying-transport chamber; a second developer passage for passing the developer from the supplying-transport chamber to the stirring-transport chamber, in which a communication portion for passing the developer from the collecting-transport chamber

Abstract: A removable unit for an electrophotographic image forming device according to one example embodiment includes a housing having an inner volume forming a toner reservoir and a channel for accumulating toner. An auger advances toner within the channel and has a rotational axis and a flight. An agitator is mounted on an inner surface of the housing and is positioned to extend toward the auger. The agitator has a first segment and a second distal segment connected to the first segment. When the auger rotates, the flight of the auger engages the agitator causing movement of the second distal segment to push toner accumulated in the channel into the auger.

Abstract: A developing device includes a developer tank and a developing roller. An internal space of the developer tank is divided into an upper conveying path, a lower conveying path, a communication path, a main pumping conveying path section, and a developer supply path, by a partition wall. A developer pumping conveying section conveys a developer inside the main pumping conveying path section in a conveyance direction Z, and includes an inner spiral blade, a rotational tube, a first outer spiral blade, a second outer spiral blade, a pumping rotation shaft member, and a pumping gear. An attracting magnet is located in a position horizontally spaced from the rotational tube.

Abstract: A cleaning member for an image forming apparatus includes a core and an elastic layer that is formed by a strip-shaped elastic member helically wound around an outer peripheral surface of the core. The cleaning member satisfies the following formula (1): 0.7<t/T<1.0??(1) where t (mm) denotes a thickness of the elastic layer, the thickness being taken in a central portion in a helical width direction of the elastic layer, and T (mm) denotes a thickness of the central portion of the strip-shaped elastic member in a width direction before wound around the outer peripheral surface of the core.

Abstract: A developing device for supplying a developer to an image bearing member is provided with a housing configured to define a passage for movement of the developer and a replenishment path configured to communicate with the passage and supply the developer to the passage; a conveyor configured to move the developer in the passage and the replenishment path; and a switching device configured to switch one moving direction to another moving direction of the developer by the conveyor to selectively move the developer toward the replenishment path.

Abstract: A toner discharge mechanism which is attached to a toner cartridge includes an auger screw for conveying and discharging a toner stored in the toner cartridge, the auger screw having an end portion downstream thereof, the end portion forming a taper portion having a predetermined length and an outer diameter diminishing toward a tip thereof; a cover member for covering the taper portion, the cover member having a conical inner wall configured to correspond to a taper shape of the taper portion; and a toner discharge outlet formed on the cover member.

Abstract: A developing device to be installed in an electrophotographic image forming apparatus including a photoconductor drum that is to have an electrostatic latent image formed on a surface thereof, the developing device comprising: a developer vessel; a developing roller that is disposed in the developer vessel; first and second developer conveying passages; and first and second developer conveying helical members circulatory conveys the developer in the first and second developer conveying passages, wherein at least one of the first and second developer conveying helical members includes an end blade at one end at a downstream side in a conveying direction, wherein the end blade includes a circumferential-direction agitating blade portion whose radial projecting size gradually increases toward the downstream side in the conveying direction; and a helical blade portion integrally wound around an outer periphery of the circumferential-direction agitating blade portion.

Abstract: There is provided a developer conveyance member that conveys a contained developer from one end side of a delivery region to other end of the delivery region while agitating the contained developer in a developer container, in which the developer is contained. Around a rotation shaft of the developer conveyance member, a spiral wing toward from one end side to other end side is formed. A plurality of paddle parts for conveying the developer in a direction that is perpendicular to a shaft core are formed around the rotation shaft in a delivery region. The paddle parts are arranged with their positions deviated in a circumferential direction.

Abstract: A powder conveyance device includes a powder container, a conveyance pipe extending downward and including first, second, and third conveyance portions disposed in that order, a first bent portion connecting together the first and second conveyance portions, bent in a direction to increase a horizontal gradient of the second conveyance portion from that of the first conveyance portion, and a second bent portion connecting together the second and third conveyance portions, bent in a direction to reduce a horizontal gradient of the third conveyance portion from that of the second conveyance portion, a powder conveyance member disposed inside the conveyance pipe, and a first powder regulator movably disposed inside the third conveyance portion of the conveyance pipe, to restrict an amount of powder discharged through the discharge port by varying a cross sectional area of a space present above a discharge port in the conveyance pipe.

Abstract: A developing device that is capable of securing an amount of developer that can be stored in a developer tank while suppressing the bending of a developer conveying section, as well as an image forming apparatus are provided. In a developer tank of a developing device, there is provided a first developer conveying section that includes a first rotation shaft member having a columnar shape in which grooves extending in an axial line direction are formed, and a first spiral blade that is spirally wound around the first rotation shaft member and conveys the developer by rotation around the axial line of the first rotation shaft member.

Abstract: A development device includes a toner-containing chamber for containing supplied toner having an interior wall, a developer-containing chamber for containing developer including toner and carrier communicating with the toner-containing chamber; and a transport screw to transport the supplied toner from the toner-containing chamber to the developer-containing chamber, disposed in the toner-containing chamber so that there is no gap between the outer edge of the transport screw and the interior wall of the toner-containing chamber in a portion lower than a level of the supplied toner in the toner-containing chamber.

Abstract: Methods are provided for operating a development station. A method comprises the steps of applying a first force at a first end of an auger and applying a second force at a second end of the auger with the first force and the second force being sufficient to rotate the auger against a drag exerted by a developer and a replenishment toner being moved by rotation of the auger; and, tensioning the auger along a length of the auger by urging the first end of the auger away from the second end and by urging the second end of the auger away from the first end.

Abstract: A transport member for a powder transport includes a revolving shaft, a transport part that extends in a helical shape relative to an axial direction of the revolving shaft, includes one end part with a free end and the other end part at an opposite side of the one end part, and transports a powder at the time of revolution of the revolving shaft, and one support part that supports the other end part of the transport part by being arranged with the revolving shaft, wherein the transport part is not supported by another support part that is arranged at an phase angle between the one support part and the another support part of 90 degrees or more, in a direction of the revolving shaft.

Abstract: An image forming apparatus which comprises a developing unit having a toner and a developer therein, the apparatus includes a toner sensor to receive a control voltage and to generate an output voltage corresponding to a remaining amount of the toner in the developing unit, a pulse width modulator to supply the control voltage to the toner sensor corresponding to a pulse width modulation (PWM) signal and a controller to control the pulse width modulator to supply the control voltage to the toner sensor to adjust a duty ratio of the PWM signal and make the output voltage reach a target value.

Abstract: Development stations are provided. A development station has a housing having a recirculation path an auger being rotatable to move the developer along at least part of the recirculation path. A drive transmission has a first output mechanically linked for movement with a first end of the auger and a second output mechanically linked for movement with a second end of the auger and distributes a force at an input end between a first force provided at the first output and at a second force provided at the second output to rotate the auger against a drag. The first force and the second force are less than a third force to drive an alternative auger from a driven end. The auger has a first end yield strength and a second end yield strength that are each less than a driven end yield strength of the alternative auger.

Abstract: A developing device comprising: a developer tank housing a developer including a toner and a carrier; a toner replenishment port; a developing roller; a first developer conveying path and a second developer conveying path; a conducting plate for peeling a recovery developer on a surface of the developing roller after the toner is supplied to a photosensitive drum from the surface of the developing roller so as to guide the recovery developer to the first developer conveying path; and first and second developer conveying members arranged on the first and second developer conveying paths, wherein the first developer conveying member has a cylindrical hollow rotating shaft with opened both ends that is rotatably provided to the first developer conveying path, and divides the first developer conveying path into an external first developer conveying path and an internal first developer conveying path, an external spiral blade fixed to an outer periphery of the hollow rotating shaft, and an internal spiral blade fi

Abstract: A developer cartridge includes a casing, a shutter member and a screw auger. The casing is configured to accommodate developer therein, the casing extending in a first direction and being formed with an opening. The shutter member is configured to be linearly movable between an open position and a closed position in the first direction, the shutter member opening the opening at the open position to permit the developer to flow out from the casing and closing the opening at the closed position to prevent the developer from flowing out from the casing. The screw auger extends in the first direction and is configured to convey the developer toward the opening, the screw auger being linearly movable in the first direction in conjunction with the movement of the shutter member.

Abstract: A developing device includes a first chamber, a second chamber, a first inlet portion, a first carrying member and an auxiliary blade. The first chamber receives a developer supplied to a developer holder. The second chamber receives the developer carried from the first chamber after being circulated between the first chamber and the second chamber. The first inlet portion allows the developer to be introduced from the second chamber to the first chamber. The first carrying member is disposed in the first chamber to carry the developer in the first chamber in a first carrying direction. The first carrying member includes a rotating shaft, a spiral blade provided at an outer periphery of the rotating shaft, and the auxiliary blade formed toward an upstream side of the first carrying direction from the spiral blade.

Abstract: A developing device and an image forming apparatus which suppress unevenness of image density are provided. A developing device includes a developer tank storing a developer, a first conveying member and a second conveying member conveying the developer, and a developing roller bearing the developer thereon. In the developing device, the first conveying member is constituted by a first rotating shaft and a plurality of first conveying blades provided along a first imaginary spiral surrounding the outer periphery of the first rotating shaft and advancing in the axial direction of the first rotating shaft at a predetermined lead angle ?X. The individual first conveying blades are separated from each other in the axial direction and are provided along the portion of less than one cycle of the first imaginary spiral.

Abstract: A method for transferring developer (14) to a development roller (11) in an electrophotographic printing process includes feeding developer from a first channel (12) to the development roller; releasing developer from the development roller to a second channel (15); and wherein a strength of a pickup field of a feed magnet (50) in the development roller increases in a direction of developer flow in the first channel.

Abstract: Methods for operating a development station are provided. In one aspect a method comprises the steps of: applying a first force at a first end of an auger and a second force at a second end of the auger with the first force and the second force being sufficient to rotate the auger against a drag exerted by the developer and the replenishment toner. Both the first force and the second force are less than a third force applied to a single driven end of an alternative auger to rotate the alternative auger against the drag and wherein the auger has a first yield strength at the first end and a second yield strength at the second end that are less than a third yield strength required to receive the third force at the driven end of the alternative auger.

Abstract: A developer accommodating container is provided with a first accommodating portion in which a first feeding member is arranged, a second accommodating portion in which a second feeding member is arranged, a first communication portion communicating the first accommodating portion and the second accommodating portion in their one end sides, a second communication portion and a third communication portion communicating the first accommodating portion and the second accommodating portion at two positions in the other end sides so as to be shifted their positions in a feeding direction of the developer, a discharge portion arranged between the second communication portion and the third communication portion in the second accommodating portion, and provided for discharging the developer, and a replenishing portion arranged in a downstream side in the feeding direction of the developer than the third communication portion in the first accommodating portion, and provided for replenishing the developer.

Abstract: A development system (10) for an electrophotographic printer with multiple augers containing a development roller (11) and a first channel contains a feed auger (13) and developer, with a plurality of paddles (12) attached to the feed auger, at least some the paddles increase in size with respect to a previous paddle along a direction of developer flow (18). This arrangement of paddles ensures that a uniform layer of developer is formed on the development roller despite the volume of developer in the first channel decreasing along the length of the first channel in the direction of developer flow.

Abstract: A developing device includes a developing vessel, first and second conveying passages for conveying a developer, first and second conveying members for agitating and conveying the developer, a developing roller, a toner supply port for receiving a supply of toner and an agitator arranged under the toner supply port. The first conveying member has a rotary shaft and first and second conveying blades formed on the periphery of the rotary shaft. The agitator is arranged coaxially with the first conveying member so as to be rotatable independently from the first conveying member. The agitator includes a circular helical blade formed around the outer periphery of the second helical blade.

Abstract: A developing device for an electrophotographic image forming apparatus includes a developing roller of a developing portion for developing an electrostatic latent image on an electrophotographic photosensitive drum, a developer accommodator, a supply opening, between the developing portion and the accommodator, and a stirring member including a support rotatably provided on the accommodator and a stirrer on the support. The stirrer's length is longer than the opening's length in a longitudinal direction of a mount mounted to the support and the length of the stirrer's end portion is shorter than the supply opening's length. When the stirrer is rotated, an end thereof enters the opening to feed the developer from the accommodator through the opening to the developing portion and then through the supply opening back to the developer accommodating portion.

Abstract: A visible image forming device is provided with an image carrier and a developing device that develops a latent image on the image carrier surface to form a visible image includes, a developer container that contains developer therein, a developer carrier carries the developer on a surface of the developer carrier and rotates oppositely to the image carrier, a first stirring member that is rotatably supported to be adjacent to the developer carrier inside the developer container and conveys the developer to be supplied to the developer carrier while stirring the developer, and a second stirring member that is rotatably supported to be adjacent to the first stirring member inside the developer container and circulates the developer by conveying the developer in the developer container oppositely to a conveyance direction of the first stirring member.

Abstract: An aspect of the invention is a powder conveying device including a conveying passage where powder is conveyed from a first powder accommodating chamber toward a second powder accommodating chamber, in the conveying passage, a conveying member including a rotating shaft rotatable, and a blade member spirally provided around the rotating shaft and enable to convey the powder by rotation of the rotating shaft, an intake region including an intake port through which the powder is taken in from the first powder accommodating chamber, a first conveying region arranged on a downstream side of the intake region in a conveying direction of the powder, and a second conveying region arranged on a downstream side of the first conveying region in the conveying direction, a conveyable volume of the powder per one revolution of the conveying member at the second conveying region being lower than that at the first conveying region.

Abstract: A developing device conveys a two-component developer on a first route of circulation and a second route of circulation, and includes a guide plate and an electromagnet that are used for choosing, in accordance with toner densities detected by two toner density detecting sensors respectively provided in the two routes, whether toner supplied from a toner supply device is guided into the first or second route of circulation. This makes it possible to provide an image forming apparatus that, even in cases where a large amount of toner is consumed at one end of a developing roller along the axial direction in a developing device provided with one toner supply opening, can form an image free from nonuniformity in image density or photographic fogs that are caused by nonuniformity in toner density of a two-component developer.

Abstract: The development device includes a development member and a circulation member. The development member develops an electrostatic latent image formed on a latent image carrier with a developer including toner and a carrier to make the electrostatic latent image visible. The circulation member receives the developer discharged from the development member and conveys the developer back to the development member. The circulation member includes a container provided upstream from the development member in a conveyance direction of the developer to store the developer. The container includes an agitator provided inside the container and agitates and mixes the developer and fresh toner supplied to the container. The agitator includes a rotatable agitation member in which one or more holes are formed through which the developer passes to mix the fresh toner and the developer to be agitated in the container.

Abstract: A developing device and image forming apparatus are provided. The developing device includes a chassis; a developer carrying member; a thickness regulating member; a supply member; and a conveying member. In a state in which the developing device is attached to a main body an opening of the chassis faces upward; the thickness regulating member pressure-contacts the developer carrying member from below the developer carrying member; the conveying member is disposed below the developer carrying member; the supply member overlaps a portion of the conveying member in a horizontal direction; and a portion of the conveying member is disposed within a vertical projection plane between a pressure-contact position of the thickness regulating member to the developer carrying member, and a contact position of the supply member to the developer carrying member. The image forming apparatus includes a main body; a plurality of photosensitive members; and a plurality of developing devices.

Abstract: An image forming apparatus and a control method thereof provides that when circulation of developer in a housing of a developing unit is deteriorated due to concentration of the developer, thus applying increased load to an agitator, the agitator is appropriately rotated forwardly and backwardly under the control of a controller. This may prevent overloading of the agitator and release the concentrated developer.

Abstract: In a developing device including a developing vessel for storing a developer, a first conveying passage, a second conveying passage, a first conveying member, a second conveying member and a developing roller, the first conveying member has a first rotary shaft and a first conveying blade formed on the periphery of the first rotary shaft, the first conveying blade has a first inner helical blade formed on the periphery of the first rotary shaft and a first outer helical blade arranged along the axis of the first rotary shaft and radially outside the outer periphery of the first inner helical blade, and the helical pitch of the first outer helical blade is specified to be shorter than the helical pitch of the first inner helical blade.

Abstract: A stir-transport member is formed on a circumferential surface of a rotation shaft with a first spiral blade, and a second spiral blade formed to overlap the region of the first spiral blade and is opposite the first spiral blade in phase and having a smaller radial-direction height than the first spiral blade. Sections of the spiral blades along the cross longitudinal direction thereof have trapezoidal shapes. The first spiral blade have a plurality of first swell portions, a part of each corresponding to a bottom of the trapezoidal shape and is more swollen than the other portions. The second spiral blade have a plurality of second swell portions, a part of each corresponding to the bottom of the trapezoidal shape and is more swollen than the other portions. The first spiral blade cross the second spiral blade at least at one of the first swell portions per turn.

Abstract: A developing unit includes a developer receiving vessel and a developer conveyance member as defined herein, the developer conveyance member includes a rotary shaft, a first conveyance member and a second conveyance member as defined herein, the second conveyance member is supported on the rotary shaft and bent in contact with the wall surface of the developer receiving chamber with rotation of the rotary shaft while conveying the developer toward the developer retainer, and the second conveyance member includes a second conveyance member body supported on the rotary shaft and located out of the overlapping range, and a second overlapping portion extending from the second conveyance member body to the other axial end of the overlapping range, designed to be movable relatively to the rotary shaft and disposed adjacently to an upstream side of the first overlapping portion in a rotation direction.

Abstract: A housing of a developing apparatus is provided with a conveying member in a developer supplying and recovering portion, and two agitating members rotating in the same direction respectively as viewing rotating shafts from a near side in an axial direction, in a developer agitating portion. A guide is provided in an inner bottom surface of the housing between two agitating members. A braking portion suppressing a discharge of a developer is provided in a downstream side of the developer agitating portion in a developer conveying direction of the first agitating member, and a discharge portion is provided in a downstream side of a disc of the braking portion.

Abstract: A housing of a developing apparatus is provided with a conveying member in a developer supplying and recovering portion, and with two agitating members rotating from the below to the above in portions opposed to each other in a developer agitating portion. A guide is provided in an inner bottom surface of the housing between two agitating members. A braking portion suppressing a discharge of a developer is provided in a downstream side of the developer agitating portion in a developer conveying direction of the second agitating member, and a discharge portion is provided in a downstream side of a disc of the braking portion.

Abstract: A housing of a developing apparatus is provided with a conveying member in a developer supplying and recovering portion, and two agitating members rotating in the same direction respectively as viewing rotating shafts from a near side in an axial direction, in a developer agitating portion. A guide is provided in an inner bottom surface of the housing between two agitating members. A braking portion suppressing a discharge of a developer is provided in a downstream side of the developer agitating portion in a developer conveying direction of the second agitating member, and a discharge portion is provided in a downstream side of a disc of the braking portion.

Abstract: A cartridge, an auger, and an image forming apparatus are provided. The cartridge includes a housing including supporting members and a conveying member, at least a portion of the conveying member rotating in an eccentric manner, the conveying member including a main body portion; a pair of supported portions provided at both ends of the main body portion and rotatably supported by the supporting members; and a spiral blade portion that conveys developer. The image forming apparatus includes an image forming apparatus main body including the cartridge. The auger includes a cylindrical main body comprising a spiral blade portion that conveys developer and shaft portions having rotational centers that coincide with each other, one of the shaft portions provided at each end of the main body, a center of gravity of the main body being displaced from the rotational centers of the shaft portions.

Abstract: A toner transferring mechanism is provided with: an agitating and transferring member disposed in a housing accommodating toner, and having a blade portion thereof formed in a spiral shape on a circumferential portion of a rotatable shaft portion; and a plurality of scraping members making contact with the agitating and transferring member, and then scraping toner adhering to the agitating and transferring member, the scraping members being arranged in an axial direction of the agitating and transferring member, wherein the scraping members are arranged so that the scraping members adjacent to each other form an interval which is approximate to a spiral pitch of the blade portion of the agitating and transferring member.

Abstract: A housing of a developing apparatus is provided with a conveying member and two agitating members. A guide is provided in an inner bottom surface of the housing between the agitating members. The guide has a mountain shape with wide foot portion in a cross sectional shape which is orthogonal to an axial direction of rotating shafts of the agitating members. The agitating members are arranged in such a manner that gaps between respective outermost portions thereof and the inner bottom surface of the housing and the guide become equal to or more than 1.5 mm and less than 3 mm. The agitating members rotate in the same direction respectively as viewing the rotating shafts from a near side in an axial direction. A discharge portion is provided on a downstream side of the developer agitating portion in a developer conveying direction of the first and second agitating members.

Abstract: An image forming apparatus includes a plurality of developing units respectively including developer inlets, the developing units are arranged side by side in a first direction, a plurality of developer containers to contain developers to be supplied to the plurality of developing units and respectively including developer outlets, the developer units are arranged side by side in the first direction to face the plurality of developing units, and a plurality of developer supplying paths respectively to connect the developer inlets to the developer outlets, wherein the plurality of developer containers include first and second developer containers, and a position of the developer outlet of the second developer container is different from position of the developer outlet of the first developer container.

Abstract: A developing apparatus according to the present disclosure is partitioned into a plurality of convey chambers which include a first convey chamber and a second convey chamber which are disposed substantially in parallel with each other, the second convey chamber has a U shape in section, a sensor disposition portion, where a toner concentration sensor is disposed on a bottom surface, is formed in an upstream with respect to a restriction portion in a developer convey direction, across a predetermined width in the developer convey direction including a detection surface of the toner concentration sensor, a distance between curved surface portions on both sides of a U-shaped inner wall surface and the second stir member is wider than another portion of the second stir chamber.

Abstract: A housing of a developing apparatus is provided with a conveying member and two agitating members. A guide is provided in an inner bottom surface of the housing between two agitating members. A guide is formed into a mountain shape with wide foot portion in a cross sectional shape which is orthogonal to an axial direction of rotating shafts of the agitating members. The guide is arranged in such a manner that a gap between respective outermost portions of two agitating members, and an inner bottom surface of the housing and the guide becomes equal to or more than 1.5 mm and less than 3 mm. Further, each of two agitating members rotates in a direction from the below to the above at a position of the guide.

Abstract: This is an auger shaft seal used in an electrophotographic marking system. The seal is made up of alternating raised and depressed pie-shaped sections, each having edges that force developer away from auger bearings. The seal of this invention can be used on bi-directional augers and will protect the bearing when the auger moves in a clockwise or counter-clockwise direction. The seal is used with a magnetic seal to add additional protection for the bearings.

Abstract: A rotary member includes a rotary shaft with a flange that projects radially out from a position near an end of the rotary shaft. A shaft end portion of the rotary shaft projects longitudinally beyond the flange and has a lubricant filling hole for receiving a lubricant. The rotary member also includes a bearing with a wall surface that has a recess. The recess has an opening and a closed depth end. The shaft end portion is accommodated in the recess so that the flange contacts the wall surface and closes off the recess to define a substantially closed space that can retain lubricant.

Abstract: A developer cartridge includes a housing for accommodating developer, a rotation shaft rotatably supported by the housing and passing across an inside of the housing, a supply opening formed in a wall of the housing opposite in a diameter direction of the rotation shaft, a return opening formed in the wall of the housing at a position displaced from the supply opening in an axial direction of the rotation shaft, a first agitation blade supported by the rotation shaft and passing through a position opposite the return opening along an inner surface of the housing, and a second agitation blade supported by the rotation shaft and passing through a position opposite the supply opening along an inner surface of the housing, wherein the first agitation blade is configured to allow the developer returned through the return opening to flow into the housing.

Abstract: A developing device includes a conveyance path, a conveyance member, a return path, and a pre-agitation region. The conveyance path conveys a toner while agitating the toner. The conveyance member has a rotational shaft, which is rotatably disposed along an upstream end to a downstream end of the conveyance path, and conveys the toner toward the downstream end due to rotation of the rotational shaft. The return path communicates with the downstream end and an intermediate portion of the conveyance path, thereby forming a circulation path, and returns the toner from the downstream end to the intermediate portion. The pre-agitation region is formed at the upstream end side, extending from the intermediate portion and outside the circulation path, and pre-agitates the toner to be conveyed to the circulation path.

Abstract: An image forming apparatus includes plural developing devices arranged at a fixed interval, plural toner cartridges arranged at an interval smaller than the interval among the developing devices, and plural sub-hoppers that receive toners stored in the toner cartridges and feed the toners to plural developing devices. The plural sub-hoppers respectively have toner receiving ports formed in positions opposed to toner discharging ports of the toner cartridges and have toner supply ports for feeding toners to the developing devices. The plural sub-hoppers are arranged at an interval same as an arrangement pitch of the developing devices.