Abstract: An absolute value of a first maximum value is smaller than an absolute value of the second maximum value. With respect to a rotational direction of a rotatable developing member, an angle from a second maximum position to a position where a magnetic flux density of a regulating pole in a normal relative to an outer peripheral surface of the rotatable developing member is a half value of the second maximum value on a side downstream of the second maximum position is smaller than an angle from a position where the magnetic flux density of the regulating pole in the normal direction relative to the outer peripheral surface of the rotatable developing member is a half value of the first maximum value on a side upstream of the first maximum position to the first maximum value.

Abstract: A controller is able to, in a case where the controller receives a correction instruction for image density, execute a phase detection mode for detecting a phase of an image bearing member and detecting a phase of a developer bearing member and change an image forming condition for an image forming unit during an image formation mode based on respective phases of the image bearing member and the developer bearing member detected in the phase detection mode and an image density of a toner pattern, and a ratio of a circumferential velocity of the developer bearing member to a circumferential velocity of the image bearing member during the phase detection mode is different from a ratio of a circumferential velocity of the developer bearing member to a circumferential velocity of the image bearing member during the image formation mode.

Abstract: An absolute value of a first maximum value is smaller than an absolute value of the second maximum value. With respect to a rotational direction of a rotatable developing member, an angle from a second maximum position to a position where a magnetic flux density of a regulating pole in a normal relative to an outer peripheral surface of the rotatable developing member is a half value of the second maximum value on a side downstream of the second maximum position is smaller than an angle from a position where the magnetic flux density of the regulating pole in the normal direction relative to the outer peripheral surface of the rotatable developing member is a half value of the first maximum value on a side upstream of the first maximum position to the first maximum value.

Abstract: A developing apparatus for developing a latent image formed on an image bearing member includes a developer carrying member configured to carry a developer including toner and magnetic carrier and including a developer carrying surface having a plurality of grooves, a magnet, provided inside the developer carrying member, configured to attract the developer on the developing carrying surface, and a regulating member, provided spaced from the developer carrying member and configured to regulate an amount of the developer carried on the developer carrying surface.

Abstract: A controller is able to, in a case where the controller receives a correction instruction for image density, execute a phase detection mode for detecting a phase of an image bearing member and detecting a phase of a developer bearing member and change an image forming condition for an image forming unit during an image formation mode based on respective phases of the image bearing member and the developer bearing member detected in the phase detection mode and an image density of a toner pattern, and a ratio of a circumferential velocity of the developer bearing member to a circumferential velocity of the image bearing member during the phase detection mode is different from a ratio of a circumferential velocity of the developer bearing member to a circumferential velocity of the image bearing member during the image formation mode.

Abstract: A developer carrying member of a developer apparatus includes a developer carrying surface having a plurality of grooves, wherein a depth D (mm) of the grooves, a width W (mm) of the grooves, and a volume average particle diameter of the magnetic carrier D50 (mm) satisfy, D (mm)>D50 (mm)×½, and W (mm)>D50 (mm), a magnet, provided inside the developer carrying member, attracts the developer on the developing carrying surface, and a regulating member, provided spaced from the developer carrying member, regulates an amount of the developer carried on the developer carrying surface. An amount M/S (mg/mm2) of the developer carried on a unit area of the developer carrying surface after passing by the regulating member, a gap SB (mm) between a free end of the regulating member and the developer carrying member, a density G (mg/mm3) of the developer, and a groove ratio ? which is a ratio of the grooves in the developer carrying surface satisfy, 0.1?M/S (mg/mm2)?0.45, 0.

Abstract: An image formation apparatus includes an image-bearing member, an exposure device, an electro-conductive member, a bias application unit and a development device having a development roller and a toner supply roller. The bias application unit configured to apply biases to the toner supply roller, the development roller, and the electro-conductive member during image formation so that a first potential difference between the toner supply roller and the development roller and a second potential difference between the electro-conductive member and the development roller cause normally charged toner to travel respectively from the toner supply roller and the electro-conductive member to the development roller, and a third potential difference between the electro-conductive member and the toner supply roller causes normally charged toner to travel from the electro-conductive member to the toner supply roller.

Abstract: An absolute value of a first maximum value is smaller than an absolute value of the second maximum value. With respect to a rotational direction of a rotatable developing member, an angle from a second maximum position to a position where a magnetic flux density of a regulating pole in a normal relative to an outer peripheral surface of the rotatable developing member is a half value of the second maximum value on a side downstream of the second maximum position is smaller than an angle from a position where the magnetic flux density of the regulating pole in the normal direction relative to the outer peripheral surface of the rotatable developing member is a half value of the first maximum value on a side upstream of the first maximum position to the first maximum value.

Abstract: With respect to a rotational direction of a rotatable developing member of a developing device, an opposing position where a regulating portion of the developing device is opposed to an outer peripheral surface of the rotatable developing member is between a first maximum position and a position where a magnetic flux density of a regulating pole in a tangential direction relative to the outer peripheral surface of the rotatable developing member is zero. With respect to the rotational direction of the rotatable developing member, the position where the magnetic flux density of the regulating pole in the tangential direction relative to the outer peripheral surface of the rotatable developing member is zero is within a range of ±2° of a midpoint between the first maximum position and a second maximum position or is downstream of the range.

Abstract: An image formation apparatus includes an image-bearing member, an exposure device, an electro-conductive member, a bias application unit and a development device having a development roller and a toner supply roller. The bias application unit configured to apply biases to the toner supply roller, the development roller, and the electro-conductive member during image formation so that a first potential difference between the toner supply roller and the development roller and a second potential difference between the electro-conductive member and the development roller cause normally charged toner to travel respectively from the toner supply roller and the electro-conductive member to the development roller, and a third potential difference between the electro-conductive member and the toner supply roller causes normally charged toner to travel from the electro-conductive member to the toner supply roller.

Abstract: A developer carrying member of a developer apparatus includes a developer carrying surface having a plurality of grooves, wherein a depth D (mm) of the grooves, a width W (mm) of the grooves, and a volume average particle diameter of the magnetic carrier D50 (mm) satisfy, D (mm)>D50 (mm)×½, and W (mm)>D50 (mm), a magnet, provided inside the developer carrying member, attracts the developer on the developing carrying surface, and a regulating member, provided spaced from the developer carrying member, regulates an amount of the developer carried on the developer carrying surface. An amount M/S (mg/mm2) of the developer carried on a unit area of the developer carrying surface after passing by the regulating member, a gap SB (mm) between a free end of the regulating member and the developer carrying member, a density G (mg/mm3) of the developer, and a groove ratio ? which is a ratio of the grooves in the developer carrying surface satisfy, 0.1?M/S (mg/mm2)?0.45, 0.

Abstract: An image forming apparatus includes an image bearing member, an exposure device configured to expose the image bearing member to form an electrostatic latent image thereon, and a developing device including a rotatable developing member configured to carry and feed a developer containing toner and a carrier to develop the electrostatic latent image formed on the image bearing member, and a magnet provided non-rotatably and stationarily inside the rotatable developing member including a developing magnetic pole, wherein magnetic chains formed by the carrier, on the rotatable developing member, magnetized by the magnet contact the electrostatic latent image formed on the image bearing member in a developing region of the rotatable developing member, wherein a maximum peak position where a magnetic flux density of the developing magnetic pole is maximum with respect to a normal direction of the rotatable developing member exists within a range of the developing region with respect to a rotational direction of th

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 apparatus includes a developer container to accommodate a developer including toner and carrier, and a conveyance screw having a helical blade spirally formed on a rotation shaft to convey the developer. The developer container has a developer discharge port at a position facing the helical blade to discharge the developer from the developer container, wherein the helical blade rotates to direct from below to above in a vertical direction at a position facing the developer discharge port. The developer discharge port has a lower edge in the vertical direction, with the lower edge having a region downstream in a developer conveyance direction from a lowermost position in the lower edge in the vertical direction, and the region in a position above the lowermost position in the vertical direction, wherein the region inclines upward as the lower edge goes downstream in the developer conveyance direction.

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 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)×1/4??×{SB (mm)+D (mm)}×G (mg/mm3)<M/S (mg/mm2).

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: A developing device includes a rotatable developing sleeve to carry and feed a developer including toner and a carrier toward a developing region, and a magnetic field generating portion provided inside the developing sleeve and having a developing magnetic pole for forming the developing region. The developing magnetic pole is disposed opposite to a closest position of the image bearing member to the developing sleeve. A ratio of an 80%-value-width of magnetic flux density of the developing magnetic 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 0.65 or more.

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 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.