Abstract: A developing apparatus includes a developer container and a conveyance member. The conveyance member comprises a blade spirally formed on a rotation shaft and is configured to rotate to convey the developer inside the developer container along the rotation shaft. The developer container has a developer discharge port at a position facing the blade to discharge an excessive developer accompanying a replenishment of the developer from the developer container. The blade rotates to direct from below to above in a vertical direction in an installation state in a facing part to the developer discharge port. The developer discharge port comprises a lower edge in the vertical direction comprising a first part positioned at a lowermost position in the vertical direction and a second part positioned downstream of the first part in a developer conveyance direction and positioned above the first part in the vertical direction.

Abstract: An image forming apparatus includes a rotatable image bearing member and a rotatable developer bearing member. The image bearing member, configured to carry a toner image, includes first recess portions provided at intervals substantially equal to a first pitch Pdr (mm) in a rotation direction of the image bearing member. The developer bearing member, configured to carry developer comprising toner and carrier and to form the toner image on the image bearing member, includes second recess portions provided at intervals substantially equal to a second pitch Ps (mm) in a rotation direction of the developer bearing member. The following relationship is satisfied Vs/Vdr<Ws/Pdr where Vdr represents a movement speed (mm/sec) of the first recess portions, Vs represents a movement speed (mm/sec) of the second recess portions, and Ws represents a length (mm) of each of the second recess portions in the rotation direction of the developer bearing member.

Abstract: Warpage of a developer regulating member formed of a magnetic material and unrotatably supported on only both end portions thereof caused when receiving pressure of developer or magnetic force is suppressed. In a cross section of the developer regulating member orthogonal to a rotational axis of the developer beading member, an area of the cross section of the developer regulating member is smaller than 28 mm2, a magnitude of a normal direction component of a second moment of area of the developer regulating member with respect to a centroid of the cross section is larger than 25 mm4, and a magnitude of a tangent direction component of the second moment of area is larger than 70 mm4. The normal direction component and the tangent direction component are respectively components in the normal direction and the tangent direction of the developer bearing member.

Abstract: A developing apparatus includes a sleeve for carrying a developer including toner and magnetic carrier, the sleeve having a plurality of grooves extending in a longitudinal direction; a magnet provided inside the sleeve, a non-magnetic regulating member, provided spaced from the sleeve, wherein an amount M/S (mg/mm2) of the developer carried on a unit area of the sleeve after passing by the regulating member, a gap SB (mm) between a free end of the regulating member and the sleeve, a density G (mg/mm3) of the developer, and a groove ratio ? which is a ratio of the grooves in the surface of the sleeve satisfy, 0.1?M/S (mg/mm2)?0.5, 0.2?SB (mm), and m/S (mg/mm2)×¼>?×{SB (mm)+D (mm)}×G (mg/mm3)<M/S (mg/mm2).

Abstract: A development device includes a magnetic field generation unit having a developing magnetic pole S2, a magnetic pole N2, and a magnetic pole N1. The magnetic poles N2 and N1 are disposed adjacent to the magnetic pole S2, at positions downstream and upstream of the magnetic pole S2 in a rotation direction of a sleeve, respectively. The magnetic pole N2 is configured to have a larger magnetic flux density and full width half maximum in a normal direction of the sleeve and have a smaller inter-pole distance from the developing magnetic pole than the magnetic pole N1, so that the rising position of magnetic brushes of developer is shifted in the upstream direction, and the magnetic brushes come into contact with a photosensitive drum more suitably.

Abstract: A developing device includes a rotatable developing sleeve for carrying a developer including toner and a magnetic carrier and for developing an electrostatic latent image, formed on an image bearing member, in a developing region where the developer contacts the image bearing member; and a magnetic field generating portion provided inside the developing sleeve and having a developing pole provided at a position opposing the image bearing member in order to form the developing region, wherein a ratio of an 80%-value-width of magnetic flux density of the developing pole with respect to a normal direction of the developing sleeve to a half peak width of the magnetic flux density of the developing magnetic pole with respect to the normal direction is 0.

Abstract: An image forming apparatus includes a rotatable image bearing member and a rotatable developer bearing member. The image bearing member, configured to carry a toner image, includes first recess portions provided at intervals substantially equal to a first pitch Pdr (mm) in a rotation direction of the image bearing member. The developer bearing member, configured to carry developer comprising toner and carrier and to form the toner image on the image bearing member, includes second recess portions provided at intervals substantially equal to a second pitch Ps (mm) in a rotation direction of the developer bearing member. The following relationship is satisfied Vs/Vdr<Ws/Pdr where Vdr represents a movement speed (mm/sec) of the first recess portions, Vs represents a movement speed (mm/sec) of the second recess portions, and Ws represents a length (mm) of each of the second recess portions in the rotation direction of the developer bearing member.

Abstract: A development device includes a magnetic field generation unit having a developing magnetic pole S2, a magnetic pole N2, and a magnetic pole N1. The magnetic poles N2 and N1 are disposed adjacent to the magnetic pole S2, at positions downstream and upstream of the magnetic pole S2 in a rotation direction of a sleeve, respectively. The magnetic pole N2 is configured to have a larger magnetic flux density and full width half maximum in a normal direction of the sleeve and have a smaller inter-pole distance from the developing magnetic pole than the magnetic pole N1, so that the rising position of magnetic brushes of developer is shifted in the upstream direction, and the magnetic brushes come into contact with a photosensitive drum more suitably.

Abstract: A developing sleeve includes first axially extending groove portions which satisfy D1?2R and W1?2R, where 2R is a volume-average particle size of a carrier, D1 is a maximum depth of each first groove portion and W1 is a width an opening of each first groove portion with respect to a circumferential direction of the developing sleeve, and second axially extending groove portions. Each second groove portion satisfies D2<2R, where 2R is the volume-average particle size of the carrier and D2 is a maximum depth of each second groove portion. Each or a plurality of the second groove portions are disposed between the first groove portions with respect to the circumferential direction of the developing sleeve.

Abstract: A developing apparatus for developing an electrostatic latent image formed on an image bearing member includes a developer carrying member, first and second accommodation chambers to accommodate developer, and a feeding screw provided in the first accommodation chamber to feed the developer. In addition, a developer accommodation portion accommodates the developer to be supplied to the first accommodation chamber and is sealed by a sealing member. A controller executes an operation in a mode in which after the developer accommodating portion starts to be unsealed at the sealing member, the feeding screw is initially rotated for a predetermined period in a direction opposite to a normal direction in which the feeding screw is rotated during the image forming operation, and after elapse of the predetermined period, the feeding screw is rotated in the normal direction.

Abstract: Only both end portions of a developer regulating member are supported by a developing container such that the developer regulating member cannot rotate, a size of an area of a cross section orthogonal to a rotational axis of a developer bearing member of the developer regulating member is smaller than 28 mm2, a magnitude of second moment of area in a normal direction of the developer bearing member with respect. to a centroid of the cross section orthogonal to the rotational axis of the developer bearing member of the developer regulating member is larger than 25 mm4, and a magnitude of a second moment of area in a tangent direction of the developer bearing member with respect to the centroid of the cross section orthogonal to the rotational axis of the developer bearing member of the developer regulating member is larger than 70 mm4.

Abstract: A developing apparatus includes a sleeve for carrying a developer including toner and magnetic carrier, the sleeve having a plurality of grooves extending in a longitudinal direction; a magnet provided inside the sleeve, a non-magnetic regulating member, provided spaced from the sleeve, wherein an amount M/S (mg/mm2) of the developer carried on a unit area of the sleeve after passing by the regulating member, a gap SB (mm) between a free end of the regulating member and the sleeve, a density G (mg/mm3) of the developer, and a groove ratio ? which is a ratio of the grooves in the surface of the sleeve satisfy, 0.1?M/S (mg/mm2)?3.5, 0.2?SB (mm), and m/S (mg/mm2)×¼??×{SB (mm)+D (mm)}×G (mg/mm3)<M/S (mg/mm2).

Abstract: A developing apparatus includes a sleeve for carrying a developer including toner and magnetic carrier, the sleeve having a plurality of grooves extending in a longitudinal direction; a magnet provided inside the sleeve, a non-magnetic regulating member, provided spaced from the sleeve, wherein an amount M/S (mg/mm2) of the developer carried on a unit area of the sleeve after passing by the regulating member, a gap SB (mm) between a free end of the regulating member and the sleeve, a density G (mg/mm3) of the developer, and a groove ratio ? which is a ratio of the grooves in the surface of the sleeve satisfy, 0.1?M/S (mg/mm2)?0.5 0.2?SB (mm), and m/S (mg/mm2)×¼??×{SB (mm)+D (mm)}×G (mg/mm3)<M/S (mg/mm2).

Abstract: A developing sleeve includes first groove portions extending in an axial direction of the developing sleeve, wherein each first groove portion satisfies D1?2R and W1?2R, where 2R is a volume-average particle size of the carrier, D1 is a maximum depth of each first groove portion and W1 is a width an opening of each first groove portion with respect to a circumferential direction of the developing sleeve, and second groove portions extending in the axial direction of the developing sleeve, wherein each second groove portion satisfies D2<2R, where 2R is the volume-average particle size of the carrier and D2 is a maximum depth of each second groove portion. Each or a plurality of the second groove portions are disposed between the first groove portions with respect to the circumferential direction of the developing sleeve.

Abstract: An image developing apparatus includes a developer carrying sleeve; a first developer chamber; a second developer chamber; a developer feeding screw in the first chamber; a first port for moving the developer from the first chamber to the second chamber; a second port for moving the developer from the second chamber to the first chamber; a supply opening for supplying the developer into the first chamber; a discharge opening adjacent to the second port for discharging the developer from the first chamber; a developer accommodating portion in the first chamber; and a controller for executing, after the developer is supplied from the developer accommodating portion, a operation in a mode in which the feeding screw is rotated for a time period in a direction opposite to a normal direction in which the feeding screw is rotated during the image forming operation and then is rotated in the normal direction.

Abstract: A developing apparatus includes a developer carrying member configured to carry a developer, and a magnet member disposed inside the developer carrying member. The magnet member includes one or more first magnet portions having a first magnetic polarity at an outer surface thereof opposing an inner surface of the developer carrying member, and one or more second magnet portions having a second magnetic polarity at an outer surface thereof opposing the inner surface. In a cross-section perpendicular to a longitudinal direction of the magnet member at a longitudinally central portion thereof, a number of the first magnet portions is larger than a number of the second magnet portions, and a ratio of a total area of the first magnet portions in the cross-section is smaller at a longitudinally end portion of the magnet member than at the longitudinally central portion.

Abstract: A developing device includes a developing container for accommodating a developer, a feeding member, including a blade for feeding the developer, and a discharge opening for permitting discharge of excessive developer. A winding direction of the blade ascends toward a downstream developer feeding direction. A first lower intersection position between a downstream edge of the discharge opening and a first cross-section perpendicular to a rotational axis of the feeding member and crossing the discharge opening is a first position, and a second lower intersection position between the downstream edge of the discharge opening and a second cross-section which is perpendicular to a rotational axis of the feeding member and crossing the discharge opening and which is provided downstream of the first cross-section is a second position, and the discharge opening is configured so that the second position is higher than the first position.

Abstract: In a developing device, the conveying ability of a second screw in a first area that includes an area, which is superposed with, in an axial direction of a developing sleeve, a developer carrying area of the developing sleeve and a downstream communicating portion through which a developer is conveyed from a developing chamber to a collecting chamber, is lower than the conveying ability of the second screw in a second area, which is positioned further downstream than the first area in a direction in which the developer is conveyed and which is superposed with the developer carrying area of the developing sleeve.

Abstract: An image forming apparatus includes: a replenishment toner container which houses toner; and a development device which forms an image by using the toner supplied from the replenishment toner container. At least two types of external additives are added to the toner. Of the two types of external additives, when an added amount of a first external additive is Wh (volume % with respect to the toner) and an added amount of a second external additive is Wl (volume % with respect to the toner), a value of Wh+Wl in initial toner of a developer housed in the development device in advance is larger than a value of Wh+Wl in replenishment toner of a developer housed in the replenishment toner container. The fluidity of the replenishment toner is higher than the fluidity of the initial toner.

Abstract: A developing device includes a first magnet fixed inside a first developer bearing member and including a pair of first repulsion magnetic poles with the same polarity and disposed adjacent to each other, and a second magnet fixed inside a second developer bearing member and including a pair of second repulsion magnetic poles with the same polarity and disposed adjacent to each other. The first magnet has a magnetic flux density distribution of a normal component of the first developer bearing member in the circumferential direction of the first developer bearing member having only one minimal point between the pair of first repulsion magnetic poles, and the second magnet has a magnetic flux density distribution of a normal component of the second developer bearing member in the circumferential direction of the second developer bearing member having a plurality of minimal points between the pair of second repulsion magnetic poles.