Abstract: An image forming apparatus includes a rotatable image bearing member and a rotatable developing member to carry developer made up of toner particles and carrier particles adhered to surfaces of the toner particles. Where a pressing force pressing the developing member against the image bearing member is F1, a total number of the carrier particles interposed between the toner particles and the image bearing member is N1, and an adhesion Ft between a carrier particle and a toner particle, measured when the carrier particle is pressed against the toner particle with F1/N1 that is a pressing force per unit carrier particle, and an adhesion Fdr1 between the carrier particle and the image bearing member, measured when the carrier particle is pressed against the image bearing member with F1/N1, satisfy Ft?Fdr1.

Abstract: A developing device includes a first transport member and a second transport member that are respectively disposed in a first transport path and a second transport path arranged in a vertical direction and that transport developer so as to circulate the developer between the first transport path and the second transport path; a developing member that is disposed to face the first transport path and that receives the developer from the first transport path; and a third transport member that is disposed in a third transport path through which the developer that has not been used by the developing member is collected and transported to the second transport path. A central shaft of the second transport member is disposed farther in a vertically upward direction than is a central shaft of the third transport member.

Abstract: An example developing device includes a housing to contain a developer and having an opening, a developing sleeve provided in the housing and partially exposed to the outside of the housing through the opening, a magnetic member including a plurality of magnetic poles and located inside the developing sleeve, and an elastic member blocking an inflow of air through a space between a downstream edge of the opening in a rotation direction of the developing sleeve and an outer circumferential surface of the developing sleeve. The elastic member includes a fixed portion fixed to the housing at a position adjacent to the downstream edge of the opening and an extension portion extending from the fixed portion in a bent form in the rotation direction of the developing sleeve to be elastically in contact with the surface of the developing sleeve.

Abstract: In a developing apparatus, a distance along an outer peripheral surface of a rotatable developing member between a first and a second maximum peak positions is less than 18 [mm], the first and the second maximum peak positions respectively corresponding to maximum values of a magnetic flux density of a first and a second magnetic poles with respect to a normal direction of the rotatable developing member. A distance along the outer peripheral surface of the rotatable developing member in a width of a value obtained by adding 2 [mT] to a minimum value of the magnetic flux density with respect to the normal direction of the rotatable developing member is 5.5 [mm] or more, at a downstream side of the first maximum peak position and at an upstream side of the second maximum peak position with respect to a rotation direction of the rotatable developing member.

Abstract: A developing device includes a developer bearer, a developer regulator, a developer supply passage, and a stopper. The developer bearer includes a magnetic field generator and is configured to bear a developer containing toner and magnetic carriers and conveys the developer to a developing area by rotation. A stopper prevents the developer blocked by the developer regulator from moving to a surface of the developer bearer, while securing a supply path for passing the developer in the developer supply passage to the developer bearer between the stopper and an upper end of a side wall of the developer supply passage that is opposite to the developing bearer. A width of the supply path in a direction perpendicular to a direction of a rotation axis of the developer bearer is in a range of 7%-10% of a circumference of an outer diameter of the developing bearer.

Abstract: A change of a magnetic flux density distribution adjacent to a regulating blade 9 opposed 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 sleeve 8 corresponding 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.

Abstract: There is provided a developing device for developing an electrostatic latent image formed on a photoreceptor with a developer to form an image, including: a developing container that contains the developer; and a developing roller that faces the photoreceptor, is arranged adjacent to the developing container, and conveys the developer contained in the developing container to the photoreceptor, wherein the developing roller includes a magnetic pole forming part to be formed with a plurality of magnetic poles along a circumferential direction of the developing roller, at least a catch pole is formed as one of the plurality of magnetic poles, and in the catch pole, an amount of a total magnetic charge in an axial direction of the developing roller is kept constant, and a part of magnetic flux density distribution is different from another part of magnetic flux density distribution along the axial direction of the developing roller.

Abstract: A developing device includes a developer bearer opposed to an image bearer, configured to bear developer and rotate in a direction of rotation of the developer bearer, and configured to develop a latent image on the image bearer and a casing opposed to the developer bearer at a position downstream from an opposed position, at which the developer bearer is opposed to the image bearer, in the direction of rotation of the developer bearer. A casing gap between the developer bearer and the casing continuously decreases or increases from a first end of the developing device to a second end of the developing device across a center of the developing device in a longitudinal direction of the developing device.

Abstract: A development device includes a developer bearing, a regulation portion, and a magnetic field generation member that is provided inside of the developer bearing member. The magnetic field generation member includes a development pole a first magnetic pole, and a second magnetic pole. The magnetic field generation member has a region satisfying |(Br(?a)?Br(?c))/10|<0.3, wherein Br(?a) is a magnetic flux density in a normal direction relative to the surface of the developer bearing member on a position shifted by ?5° from a point nearest to the regulation portion on the developer bearing member around a center of the developer bearing member, and Br(?c) is the magnetic flux density around the developer bearing member on a position shifted by +5° from the point nearest to the regulation portion on the developer bearing member.

Abstract: A developing device includes a developing roller which includes: a magnet roller having a plurality of magnetic poles in a circumferential direction; and a developing sleeve rotatably supported along an outer peripheral surface of the magnet roller, and which is configured to supply a toner to an image bearing member. The magnet roller is configured so that the relative position thereof to the developing sleeve is changeable.

Abstract: With a first line segment being a line segment that joins an axis line of a developer carrier and an axis line of an image carrier, a second line segment being a line segment that joins a position, which is a position on the surface of the developer carrier at which the magnetic flux density of a magnetic pole is maximal, and the axis line of the developer carrier, and a third line segment being a line segment that joins a downstream end portion, in a rotation direction of the developer carrier, then among angles in the rotation direction of the developer carrier, a first angle formed by the first line segment and the second line segment is larger than 0° and equal to or smaller than a second angle formed by the first line segment and the third line segment.

Abstract: A developing device includes a housing, a developing roller, a developer stirring member, and a layer thickness regulating member. The developing roller includes a stationary magnet and a sleeve. The stationary magnet includes a first magnetic pole having a specific polarity, and a second magnetic pole lying downstream of the first magnetic pole and having the same polarity as the first magnetic pole. In an entire inter-pole region between the first magnetic pole and the second magnetic pole, the stationary magnet produces a magnetic force including a horizontal component that keeps the specific polarity and has a value greater than zero (mT). The inter-pole region includes a flat area where a horizontal magnetic force component having a minimum absolute value exits and the horizontal magnetic force component changes within a range of 0.5 (mT) or less, the flat area extending over a range of 10 degrees or more.

Abstract: A developing device includes: a developing roller that rotates in a given rotation direction; and a regulating portion that regulates the amount of feed of developer. The developing roller includes a circumferential surface on which a regulating pole having single polarity is formed. At the regulating pole, a magnetic flux density in a direction normal to the circumferential surface of the developing roller takes a maximum in a first position on the circumferential surface in the rotation direction and takes a value half of the maximum in a second position and a third position on the circumferential surface in the rotation direction. The first position is shifted downstream from a intermediate position between the second and third positions. A tip portion of the regulating portion faces a position between the first position and the intermediate position or faces the first position.

Abstract: A developing device includes a developing sleeve and a regulation portion. The developing sleeve includes a magnetism generating portion to which magnetic poles are attached. The developing sleeve holds a developer on an outer circumferential surface. The regulation portion includes a magnetic plate. A first segment connecting a peak position of the magnetic pole disposed at a position facing the magnetic plate and an axial center of the developing sleeve has an angle, with respect to a second segment connecting the magnetic plate and the axial center, equal to or less than 7 degrees on a downstream side in a rotation direction of the developing sleeve and equal to or less than 6 degrees on an upstream side in the rotation direction. An angle of a half value width of the magnetic pole is equal to or greater than 41 degrees to equal to or less than 52 degrees.

Abstract: A development roller according to the present invention includes a magnet roller in which a magnet portion generating a magnetic force and a shaft portion projecting from the magnet portion are formed integrally, wherein a recess is provided on an end surface of the magnet portion on a side of the shaft portion.

Abstract: A method and apparatus for retracting a magnetic brush in an imaging device. The apparatus includes a housing containing carrier beads and toner particles; a magnetic structure at least partly disposed within the housing and generating at least one magnetic field; and an endless sleeve disposed around and rotatable about the magnetic structure, at least a portion of the sleeve extending from the housing. During toner development, the magnetic structure is in a first position for developing a magnetic brush of the carrier beads and toner particles along the portion of the sleeve extending from the housing which forms a developer nip with a photoconductor, and during a period of time when toner development is not to be performed, the magnetic structure is in a second position for retracting the magnetic brush by causing the carrier beads to be positioned against the portion of the endless sleeve extending from the housing forming the developer nip.

Abstract: A developing device includes a developing sleeve for carrying a developer for developing an electrostatic latent image formed on an image bearing member, a magnet for carrying the developer on the sleeve, and a regulating member for regulating an amount of the developer carried on the sleeve. Magnetic poles of the magnet are disposed so that a circumferential direction component of a magnetic force acting on a magnetic carrier of the developer contacting at least a part of an upstream regulating surface of the regulating member with respect to the direction of rotation of the sleeve is opposite from the direction of the rotation.

Abstract: Provided is a developing device including a storage container that stores a developer, a rotating body that supplies the developer to an image holding member in a supply region by being rotated with holding the developer, an inflow portion that is provided with an inflow port placed on a downstream side of the supply region in a rotation direction of the rotating body, and flows air into the storage container, and an outflow portion that is provided with an outflow port and emits air in the storage container from the outflow port, wherein the outflow port and the inflow port are placed to be adjacent to each other.

Abstract: A developing device includes a developing member including a magnet member on which plural magnetic poles including a developing main magnetic pole are magnetized in a circumferential direction and a developer holder that faces an image supporting member, receives the magnet member, and holds a developer, wherein a distribution of a magnetic attraction force in a circumferential direction has a gradient that increases toward a downstream end from an upstream end of a developing area in a developer transport direction of the developer holder, and the magnetic poles are magnetized on the magnet member so that the amount of the increase of the magnetic attraction force between the upstream end and a middle position of the developing area is larger than that between the middle position and the downstream end.

Abstract: There are provided a developing device capable of preventing occurrence of image unevenness by releasing a developer residing on a surface of a developing roller reliably, and an image forming apparatus. An angle ? formed by a first plane including a position at which a magnetic flux density in a normal direction by a removing pole becomes a maximal value on a surface of the developing sleeve and a rotational axis of a developing sleeve, and a second plane including a first axis of a first rotational shaft section of a first agitating conveyance section and the rotational axis of the developing sleeve 17 is 20° or more and 40° or less.

Abstract: A method and apparatus for retracting a magnetic brush in an imaging device. The apparatus includes a housing containing carrier beads and toner particles; a magnetic structure at least partly disposed within the housing and generating at least one magnetic field; and an endless sleeve disposed around and rotatable about the magnetic structure, at least a portion of the sleeve extending from the housing. During toner development, the magnetic structure is in a first position for developing a magnetic brush of the carrier beads and toner particles along the portion of the sleeve extending from the housing which forms a developer nip with a photoconductor, and during a period of time when toner development is not to be performed, the magnetic structure is in a second position for retracting the magnetic to brush by causing the carrier beads to be positioned against the portion of the endless sleeve extending from the housing forming the developer nip.

Abstract: A magnet roller includes a roller-shaped body constructed of a magnetic field generating material, a first support rod provided to a first axial end of the body; and a second support rod provided to a second axial end of the body. At least one of the first and second support rods is constructed of a nonmagnetic material and includes a projecting part projecting outside the body from an end face of the body and a buried part united to the projecting part and positioned inside the body. The buried part includes a reduced-area portion smaller than a base end of the projecting part adjacent to the buried part in cross-sectional area perpendicular to an axial direction of the first and second support rods.

Abstract: A developing device of the present disclosure includes a magnetic roller and a developing roller arranged so as to oppose the magnetic roller. Inside the magnetic roller, a regulation pole and a conveyance pole are provided. The regulation pole is turned toward an opposing surface side of an end portion of a regulation blade provided in a developer container. The regulation pole and the conveyance pole are arranged such that in magnetic fields formed by these magnetic poles, a point where no magnetic pole perpendicular to a surface of the magnetic roller is generated is located in a gap between the surface of the magnetic roller and the regulation blade.

Abstract: An image forming apparatus includes an image carrier, a developing unit, and a developer sucking section. A relationship 0?X?R+kRW (where k=10 to 12) is established, when X (m) is a distance from a center of a transport pole to a position where a straight line crosses a rotating section, R (m) is a chain standing length of developer on the transport pole, W (m/s) is a peripheral velocity of the developing unit, and k is a coefficient. The transport pole is adjacent to a development pole and is situated downstream of the development pole in a direction of rotation of the rotating section. The straight line is situated at a downstream side in the direction of rotation of the rotating section and connects a center of rotation of the developing unit and an end of the developer sucking section.

Abstract: A two-component developer includes toner and a magnetic carrier. The two-component developer is used in a developing device including a circular cylindrical developer transporting member that is disposed so as to be separated by 125 ?m to 250 ?m from a latent image carrier that rotates. The two-component developer is used so as to satisfy a condition in which a width of a region where a magnetic brush contacts a surface of the latent image carrier is in a range of from 1.0 mm to 2.25 mm, and a condition in which a developer density of the region where the magnetic brush contacts the surface of the latent image carrier is in a range of from 0.75×10?6 to 1.50×10?6 g/m3.

Abstract: A developing device includes a magnetic roller, a developing roller, a cover, a first magnetic force generator, a second magnetic force generator with a different polarity, and a movement controller. A roller surface of the magnetic roller holds toner and magnetic carrier, the toner being adhered to the magnetic carrier. The developing roller is arranged to face the magnetic roller. The first magnetic force generator is provided inside the magnetic roller such that a magnetic pole face thereof faces the developing roller. The second magnetic force generator is provided inside the developing roller so as to be able to move between a first position and a second position. A magnetic pole face of the second magnetic force generator faces the magnetic roller at the first position and faces the cover at the second position. The movement controller causes the second magnetic force generator to move between positions.

Abstract: A drawing-up magnetic pole and a control magnetic pole of a magnetic field generator that is disposed in a developer carrier are adjacent to each other and a prevention member is provided that secures, between the prevention member and an upper end of a side wall of a developer supply conveyance path, a supply path through which a developer in the developer supply conveyance path passes toward the developer carrier at least over the entire width of a developing area and that prevents a control retained developer, which is prevented by a developer control member from passing through a control gap, from moving toward the surface of the developer carrier along lines of the control magnetic force. The peak of the magnetic flux density of the drawing-up magnetic pole in the normal direction is disposed below the lower end of the supply path.

Abstract: A developing apparatus includes a developer carrying member for carrying a developer; and a magnetic member including a plurality of magnet pieces disposed inside the developer carrying member along a circumferential direction of the developer carrying member. The magnetic member includes one or more first magnet pieces having the same magnetic polarity at a surface opposing an inner surface of the developer carrying member, and one or more second magnet pieces having the other magnetic polarity opposing the inner surface of the developer carrying member. A total sum of the first magnet pieces is larger than a total sum of the second magnet pieces, and a ratio of the total sum of a volume of the first magnet pieces to a space occupied by the magnetic member is smaller at an end portion than in a central portion with respect to a longitudinal direction of the magnetic member.

Abstract: A developing device includes a developer carrier which carries a developer containing a toner and a carrier, and a developing chamber which feeds the developer to the developer carrier. In addition, a conveying member conveys the developer of the developing chamber, and a regulating member regulates an amount of the developer coated on the developer carrier. A guide portion guides the developer to the developer carrier and forms a buffer portion that temporarily contains the developer fed from the developing chamber between the regulating member and the guide portion. The guide portion has a facing surface opposing the developer carrier along a front surface of the developer carrier and a guiding surface which guides the developer from an upper edge of the guide portion to a downstream side of the facing surface in a rotational direction of the developer carrier.

Abstract: A developing device includes: a developer carrying member; a magnet; a developing chamber; a blade member; and a guiding portion. A distance from a developer feeding start position of the guiding portion to said blade member is 2 mm or more along a developer carrying member rotational direction. When a magnetic force at a surface of the developer carrying member with respect to a direction normal to the developer carrying member is Fr, the magnetic poles are provided so that a ratio of an integrated value FrNear obtained by integrating the magnetic force Fr from the blade member to a position of 2 mm upstream of the blade member with respect to the rotational direction to an integrated value FrAll obtained by integrating the magnetic force from the blade member to the developer feeding start position with respect to the rotational direction is 60% or more.

Abstract: A developing device includes a first developer carrier that carries developer on a peripheral surface thereof; a second developer carrier that carries the developer on a peripheral surface thereof; a supplying section that supplies the developer to the peripheral surface of the first developer carrier; a layer thickness regulating member that regulates a layer thickness of the developer supplied to the peripheral surface of the first developer carrier by the supplying section; a first transfer magnetic pole disposed in an interior of the first developer carrier; a second transfer magnetic pole disposed in an interior of the second developer carrier; a first downstream magnetic pole disposed in the interior of the first developer carrier; and a second downstream magnetic pole disposed in the interior of the second developer carrier.

Abstract: An image forming apparatus includes an image carrier, a developer container, a moving mechanism that moves a toner of a developer to the image carrier, a stirring and transporting member that transports the developer in the developer container to the moving mechanism, a layer thickness regulating member that regulates the layer thickness of the developer held by a developer holder of the moving mechanism, and a movement regulating unit that regulates movement of the developer. An end of the movement regulating unit at a stirring and transporting member side is located at the stirring and transporting member side with respect to a tangent line tangent to the outer circumference of the stirring and transporting member and passing through a position where the density of magnetic flux of an attraction magnetic pole of a magnet member of the moving mechanism on the surface of the developing holder is the highest.

Abstract: A developing roller includes a cylindrical transporting member and a magnet member. The transporting member is disposed so as to rotate with a gap being disposed between the transporting member and a latent image carrying member that rotates. The transporting member carries and transports magnetic developer, and is formed of a nonmagnetic material. The magnet member is disposed with multiple magnetic poles being fixed in a cylindrical interior of the transporting member. In the developing roller, multiple magnetic members are disposed in a regular arrangement at a carrying surface of the transporting member that carries the developer.

Abstract: A longitudinal end portion of an opposing magnetic member of a developer supporting rotator is positioned more longitudinally outside than a longitudinal end portion of a toner supporting side magnetic member. With respect to the opposing magnetic member facing the toner supporting side magnetic member and a downstream magnetic member disposed more downstream than the opposing magnetic member in a rotational direction, a magnetic force generated in a vicinity of both longitudinally end portions thereof is greater than a magnetic force generated longitudinally inside thereof. A housing includes a sealing portion that projects from a position facing a face at a longitudinal end portion of the developer supporting rotator toward the face, such that the sealing portion prevents the toner in a space between the face and an inner face of the housing from scattering outside.

Abstract: Provided is a developing device including a pair of developer holding members that include a pair of cylinder members, which are disposed close to each other and rotate in the same direction at an adjacent gap at which both cylinder members are in close proximity, and a pair of magnetic force generation sections which are provided inside the pair of cylinder members respectively and generate magnetic forces for holding a developer on the cylinder members, and a pair of developing magnetic poles that are provided in the pair of magnetic force generation sections respectively, are disposed to be opposed to a latent image holding member, and are set to have the same polarity.

Abstract: A developing device includes a developing roller, a magnetic roller opposed to the developing roller so as to form a magnetic blush, a high voltage power supply including a transformer having secondary side outputs one of which is connected to the developing roller while the other output is connected to the magnetic roller, so as to apply AC voltages to the developing roller and the magnetic roller, a detection portion for detecting occurrence of discharge between the developing roller and the photoreceptor drum, a restriction portion for restricting movement of toner from the magnetic roller to the developing roller, and a moving portion configured to move the restriction portion in discharge start voltage detection mode so as to restrict toner movement to the developing roller.

Abstract: A developing device includes a sleeve and a magnet roller having first and second magnetic poles, the second magnetic pole being disposed downstream of the first magnetic pole. A magnetic attraction distribution on the sleeve in a region from the first magnetic pole to the second magnetic pole is such that the magnetic attraction decreases from a position of the first magnetic pole toward the downstream side, a gradient of change in the magnetic attraction decreases in a region downstream of a region in which a gradient of reduction in the magnetic attraction temporarily increases, thereby forming an attraction reduction region in which the magnetic attraction is reduced so that developer cannot be held on the sleeve, and the gradient of change in the magnetic attraction increases in a region downstream of the attraction reduction region so that the magnetic attraction increases to a position of the second magnetic pole.

Abstract: An image forming apparatus includes a developer containing part, a developer mixer, a mixer drive motor, a magnetic sleeve, a sleeve drive motor, a mixer rotation speed determination part and a motor drive controller. The developer containing part contains a two-component developer including a toner and a carrier. The developer mixer is provided in the developer containing part, agitates the two-component developer, and charges the toner and the carrier. The mixer rotation speed determination part determines the mixer rotation speed of the mixer drive motor according to a supply amount of the toner supplied to the developer containing part from a toner cartridge by driving of a toner supply motor. The motor drive controller independently performs rotation control of the sleeve drive motor and the mixer drive motor, and rotates and controls the mixer drive motor at the mixer rotation speed determined by the mixer rotation speed determination part.

Abstract: A developing device includes: a developing member including a magnetism-generating member having plural magnetic poles polarized in a circumferential-direction thereof, and a rotating member that is rotated about the magnetism-generating member; a developer-pumping pole provided in the magnetism-generating member, and that pumps up the developer, which is supplied from a developer accommodating portion, to the rotating member surface; a developer-peeling-off pole provided in the magnetism-generating member below a rotation axis of the rotating member in a vertical direction on an upstream side of the developer-pumping pole in a rotational-direction of the rotating member, that peels off the developer from the rotating member surface; and a magnetic body provided in at least a portion between a facing position facing the developer-peeling-off pole in a circumferential-direction of the rotating member and an intermediate position between the developer-peeling-off pole and the developer-pumping pole in the circu

Abstract: A developing device including a developer container and a developer bearing member is provided. The developer container contains a two-component developer comprising toner particles and magnetic carrier particles having a ten-point average surface roughness Rz of 0.5 to 3.0 ?m. The developer bearing member is a cylindrical member containing a magnetic field generator having multiple magnetic poles. The developer bearing member is adapted to bear the two-component developer on a surface thereof and to convey the two-component developer as the surface rotates. The developer bearing member has a ten-point average surface roughness Rz of 10 to 30 ?m. The multiple magnetic poles include three developer bearing poles each adapted to generate a magnetic field having a strength enough for retaining the two-component developer on a surface of the developer bearing member. The three developer bearing poles consist of a developing pole, a pre-developing pole, and a post-developing pole.

Abstract: A developing device having: a developing sleeve in which a magnetic member is inserted, transporting two-component developer to a developing area facing an image carrier; and a restriction member for restricting the amount of developer to be no greater than 250 g/m2. The average of absolute values of magnetic flux density within a restriction area falls within a range of 40 mT to 70 mT under a condition that no developer exists within the restriction area. The restriction area extends along the outer circumferential surface between a closest point on the outer circumferential surface, which is closest to the restriction member, and a point 2 mm upstream from the closest point in a rotational direction of the developing sleeve, and has a height that is half a minimum distance between the closest point and the restriction member.

Abstract: The developing device includes: a developing container that stores a developer including a non-magnetic toner and a magnetic carrier; a toner bearing member that bears the toner and conveys the toner to a developing portion; and a separating portion wherein a surface of the toner bearing member includes a plurality of recess structures in which a smallest opening width R is equal to or larger than rt10 and equal to or smaller than rc10, and a depth D is equal to or larger than rt10/2, where rt10 is a particle diameter in which an accumulated number distribution in a toner granularity distribution is 10%, and rc10 is a particle diameter in which an accumulated number distribution in a carrier granularity distribution is 10%; and a percentage of the recess structures per unit area in a toner bearing region of the toner bearing member is equal to or larger than 55%.

Abstract: A magnet roller according to the present invention comprises: a single metal shaft member; and a pair of first and second semicylindrical resin magnet members each of which is shorter than the metal shaft member and has a first or second annular portion integrally provided at one end portion thereof. Each of first and second central holes is provided at the center of each of the first and second annular portions. The magnet roller according to the present invention is assembled by arranging the first annular portion and the second annular portion so as not face each other, inserting both end portions of the metal shaft member into the first and second central holes from the inner side of the first and second annular portions, and sandwiching the metal shaft member between the first and second semicylindrical resin magnet members in such a manner that both the end portions of the metal shaft member protrude to the outside of the first and second annular portions.

Abstract: A developing device includes a developing member including a scooping pole generating the magnetic lines of force to scoop up a developer, rotating while holding the developer scooped up by the scooping pole on a surface thereof, and supplying the developer to an image holding body to develop the electrostatic latent image, and an agitation transport unit that is disposed at a position where a developer used for development and separated and falling from the developing member is received, rotates about a rotating shaft extending along a rotating shaft of the developing member, agitates the developer, and transports the agitated developer to a scoop position, wherein the scooping pole is disposed on the downstream side of a line, which connects the rotating shaft of the developing member with the rotating shaft of the agitation transport unit, in a rotation direction of the developing member.

Abstract: A development roller according to the present invention includes a magnet roller in which a magnet portion generating a magnetic force and a shaft portion projecting from the magnet portion are formed integrally, wherein a recess is provided on an end surface of the magnet portion on a side of the shaft portion.

Abstract: A developer includes a developer carrying body that carries a two-component developer having a magnetic toner and a carrier. A toner carrying body opposes the developer carrying body and receives toner from the developer carrying body. An image carrying body develops an electrostatic latent image by toner carried on the toner carrying body. A first magnetic member is inside the developer carrying body and opposes a surface of the toner carrying body. A second magnetic member is inside the toner carrying body and opposes the surface of the developer carrying body. The second magnetic member is magnetized to an opposite polarity to the first magnetic member and generates a magnetic force at least on the surface of the toner carrying body in a range of 25 mT to 40 mT in a direction perpendicular to the surface of the toner carrying body.

Abstract: A developing device to develop a latent image includes a developer bearer including a rotatable, hollow developer supporter to carry two-component developer on a surface thereof, and a stationary magnetic field generator having multiple magnetic poles and disposed inside the hollow developer supporter, and a magnetic field adjuster. The magnetic field generator generates a magnetic flux on the surface of the hollow developer supporter, and the magnetic field adjuster suppresses a maximum value of magnetic flux density in a tangential direction to the surface of the hollow developer supporter from a predetermined value for image formation.

Abstract: A development device includes a developer bearer to carry the developer to a development range, a magnetic field generator disposed inside the developer bearer for generating magnetic force, a developer regulator for adjusting an amount of the developer, a developer supply compartment disposed adjacent to the developer bearer, separated by a side wall from a portion where the developer bearer is provided, a developer agitator provided in the supply compartment, and a blocker disposed above the side wall of the supply compartment across a supply gap through which the developer moves from the supply compartment. The magnetic field generator has an attraction magnetic pole and a regulation magnetic pole. The blocker prevents the developer blocked by the developer regulator from moving along a magnetic force line of the regulation magnetic force toward the circumferential surface of the developer bearer.

Abstract: A development device includes a developer bearer to carry by rotation two-component developer to a development range to develop a latent image formed on a latent image bearer, a magnetic field generator disposed inside the developer bearer, a developer regulator for adjusting an amount of the developer on the developer bearer, positioned upstream from the development range in a rotational direction of the developer bearer and facing the developer bearer across a regulation gap, a supply compartment from which the developer is supplied by a developer agitator to the developer bearer, a collection compartment, a pre-regulation portion adjacent to and upstream from the developer regulator in the rotational direction of the developer bearer, and a developer mobility adjuster that makes mobility of the developer in the pre-regulation portion higher on an upstream side in a developer conveyance direction in the supply compartment.

Abstract: An image forming apparatus includes: a developing device that allows a developer to be retained on a developer carrier having a magnet member equipped with a plurality of magnetic poles mounted on an inner periphery thereof and rotates the developer carrier to deliver the developer to an image carrier and that forms a toner image by supplying the toner of the developer to the image carrier by applying a developing bias voltage from a bias voltage source between the developer carrier and the image carrier; a transfer device for transferring the toner image formed on the image carrier to a transfer receiving material; a toner recovery device for recovering the toner remaining on the surface of the image carrier after the transfer of the toner image; and a toner return device for returning to the developing device the toner recovered by the toner recovery device.