Abstract: An image forming apparatus includes a density detecting portion configured to detect a density of a control toner image being formed every time when an image is formed on a predetermined number of sheets in successively forming the image on sheets, and a control portion configured to control an amount of supplying developer. The control portion controls forming of the control toner image so that the predetermined number of image-formed sheets is a first number in a period of time from when the use of a developing apparatus is started, until when an amount of developer of the developing apparatus reaches a set value which is larger than an amount of initial developer, and the predetermined number of image-formed sheets is a second number which is larger than the first number of image-formed images, after the amount of developer of the developing apparatus reaches the set value.

Abstract: A first amount of developer is sealed in a container of a developing unit in an initial state where the developing unit is not yet used. A discharge portion is configured to discharge the developer from the container in a case where the developer contained in the container exceeds a predetermined amount greater than the first amount. A permeability sensor is configured to output a detection signal correlated with a magnetic permeability of the developer within the container. A controller is configured to use different values of a control signal, for adjusting an input-output relationship between the magnetic permeability of the developer in the container and the detection signal output from the permeability sensor, in a state where a second amount greater than the first amount of the developer is contained in the container and in a state where the first amount of the developer is contained in the container.

Abstract: A developing device includes a developing container, a rotatable member including a first screw portion and a second screw portion, a first feeding path configured to accommodate the first screw portion, a second feeding path provided in communication with the first feeding path at a position downstream of the second screw portion with respect to a develop feeding direction, and a developer discharging opening provided in the second feeding path. In a state in which the developing device is mounted to the image forming apparatus, in a cross section of the second feeding path perpendicular to a rotational axis of the rotatable member, the second feeding path includes a region where a distance between side surfaces of the second feeding path in a side above a center of a rotation shaft of the rotatable member with respect to a vertical direction increases upwardly.

Abstract: In the present invention, an image forming apparatus using a method of replacing a developer is configured such that an immobile area in which the heights of a discharge passage and a conveyance passage are changed on the upstream side of a returning screw is filled. This causes the immobile area of the developer to be unlikely to occur and accordingly suppresses formation of a toner stain image due to an aggregation toner, enabling stable image formation over a long period of time.

Abstract: A developing device includes a developing container, a rotatable member including a first screw portion and a second screw portion, a first feeding path configured to accommodate the first screw portion, a second feeding path provided in communication with the first feeding path at a position downstream of the second screw portion with respect to a develop feeding direction, and a developer discharging opening provided in the second feeding path. In a state in which the developing device is mounted to the image forming apparatus, in a cross section of the second feeding path perpendicular to a rotational axis of the rotatable member, the second feeding path includes a region where a distance between side surfaces of the second feeding path in a side above a center of a rotation shaft of the rotatable member with respect to a vertical direction increases upwardly.

Abstract: When ending image forming, a state is realized where charging by a charging roller is stopped (charging bias off) and also applying DC voltage at a developing device is stopped (developing bias DC off). In this state, AC voltage is applied to the developing device (developing bias AC on), thereby adhering toner to the surface of a photosensitive drum and forming interposing toner. Driving of the photosensitive drum and an intermediate transfer belt is then stopped in the state with the interposing toner interposed between the photosensitive drum and intermediate transfer belt.

Abstract: A developing apparatus includes a developing container containing a developer and a stirring-conveying screw configured to feed the developer. The stirring-conveying screw includes a first feeding screw portion to feed the developer in a first direction, a second feeding screw portion to feed the developer in an opposite direction, and a third feeding screw portion. A first feeding passageway accommodates parts of the feeding screw portions, and a second feeding passageway is provided in fluid communication with the first feeding passageway. A bottom surface portion is disposed proximate to the communication opening and has a first portion provided at a position higher than a bottom surface of the second feeding screw and a second portion provided at a position lower than a bottom-most portion of the communication opening. The bottom surface portion is located downstream of the second feeding screw and faces the third feeding screw.

Abstract: A developing device includes a developing container, a rotatable member including a first screw portion and a second screw portion, a first feeding path configured to accommodate the first screw portion, a second feeding path provided in communication with the first feeding path at a position downstream of the second screw portion with respect to a develop feeding direction, and a developer discharging opening provided in the second feeding path. In a state in which the developing device is mounted to the image forming apparatus, in a cross section of the second feeding path perpendicular to a rotational axis of the rotatable member, the second feeding path includes a region where a distance between side surfaces of the second feeding path in a side above a center of a rotation shaft of the rotatable member with respect to a vertical direction increases upwardly.

Abstract: A developing device includes a developing container, a developing sleeve, a magnet and grooves provided at a surface of the sleeve and formed along a direction crossing a circumferential direction of the sleeve. In a cross-section, each of the grooves is formed by a flat bottom portion contacting a carrier particle and a pair of side surface portions provided in both sides of the flat bottom portion with respect to the circumferential direction of the sleeve and satisfies the following relationship: r<w<2r, 2×r<L, and r/2?s<2r. In the above, r is a volume-average particle size of the carrier particles, w is a length of the flat bottom portion, L is a width between the side surface portions at the surface of the sleeve, and s is a depth of each of the grooves.

Abstract: A developing device includes a developing container, a developing sleeve, a magnet and grooves provided at a surface of the sleeve and formed along a direction crossing a circumferential direction of the sleeve. In a cross-section, each of the grooves is formed by a flat bottom portion contacting a carrier particle and a pair of side surface portions provided in both sides of the flat bottom portion with respect to the circumferential direction of the sleeve and satisfies the following relationship: r<w<2r, 2×r<L, and r/2?s<2r. In the above, r is a volume-average particle size of the carrier particles, w is a length of the flat bottom portion, L is a width between the side surface portions at the surface of the sleeve, and s is a depth of each of the grooves.

Abstract: A developing unit includes a developing container, a developing sleeve, a developer regulating member, and a magnetic field generating portion. The magnetic field generating portion includes a drawing-up pole and a cut pole. In addition, in a peak-to-peak area, the magnetic field generating portion includes at least one of an Fr flat area in which Fr is substantially constant and an Fr attenuation area in which Fr attenuates toward the cut pole side from the drawing-up pole side, and is configured that F? is oriented toward the same direction as a direction of rotation of the developing sleeve in the entire peak-to-peak area.

Abstract: In the present invention, an image forming apparatus using a method of replacing a developer is configured such that an immobile area in which the heights of a discharge passage and a conveyance passage are changed on the upstream side of a returning screw is filled. This causes the immobile area of the developer to be unlikely to occur and accordingly suppresses formation of a toner stain image due to an aggregation toner, enabling stable image formation over a long period of time.

Abstract: A developing device includes a developing container, a rotatable member including a first screw portion and a second screw portion, a first feeding path configured to accommodate the first screw portion, a second feeding path provided in communication with the first feeding path at a position downstream of the second screw portion with respect to a develop feeding direction, and a developer discharging opening provided in the second feeding path. In a state in which the developing device is mounted to the image forming apparatus, in a cross section of the second feeding path perpendicular to a rotational axis of the rotatable member, the second feeding path includes a region where a distance between side surfaces of the second feeding path in a side above a center of a rotation shaft of the rotatable member with respect to a vertical direction increases upwardly.

Abstract: When ending image forming, a state is realized where charging by a charging roller is stopped (charging bias off) and also applying DC voltage at a developing device is stopped (developing bias DC off). In this state, AC voltage is applied to the developing device (developing bias AC on), thereby adhering toner to the surface of a photosensitive drum and forming interposing toner. Driving of the photosensitive drum and an intermediate transfer belt is then stopped in the state with the interposing toner interposed between the photosensitive drum and intermediate transfer belt.

Abstract: A developing device includes a developing container, a developing sleeve, a magnet and grooves provided at a surface of the sleeve and formed along a direction crossing a circumferential direction of the sleeve. In a cross-section, each of the grooves is formed by a flat bottom portion contacting a carrier particle and a pair of side surface portions provided in both sides of the flat bottom portion with respect to the circumferential direction of the sleeve and satisfies the following relationship: r<w<2r, 2×r<L, and r/2?s<2r. In the above, r is a volume-average particle size of the carrier particles, w is a length of the flat bottom portion, L is a width between the side surface portions at the surface of the sleeve, and s is a depth of each of the grooves.

Abstract: A developing apparatus includes a developer container; a feeding screw for feeding a developer in a first direction in the container; a returning screw provided at a position downstream of the feeding screw in the first direction to feed the developer in a second direction opposite thereto; a opening provided in a downstream end surface of a feeding path of the feeding screw, the opening being disposed at the position higher than a bottom surface of an area to which the feeding screw is opposed, and being capable of permitting discharge of a excessive developer resulting from developer supplying into the container; and a higher bottom portion provided between the end surface and an upstream end portion of the returning screw with respect to the second direction and having a surface higher than the bottom surface of the opposing area and lower than a lower end of the opening.

Abstract: A developing apparatus, includes a developer carrying member; a containing portion configured to contain developer; a discharge outlet through which a surplus of the developer is discharged; a first conveying portion configured to convey the developer; a second conveying portion provided downstream of the first conveying portion in a conveying direction of the first conveying portion and having a spiral blade portion configured to convey the developer in a conveying direction opposite to the conveying direction of the first conveying portion; and a disk portion provided upstream of the second conveying portion in the conveying direction of the second conveying portion, the disk portion being formed to project radially-outwardly from a whole circumference of a rotary shaft. An upstream end of the spiral blade portion of the second conveying portion in the conveying direction of the second conveying portion and the disk portion are arranged with an interval therebetween.

Abstract: A developing device includes a developer carrying member and first and second chambers. A feeding member provided in the second chamber includes a normal feeding portion, a reverse feeding portion, and a discharging portion. An opposing portion in the second chamber opposes a peripheral surface of the reverse feeding portion and is formed so that a first region of an upper half of the reverse feeding portion is broader in clearance with the second chamber than a second region, and includes a projected portion for forming a predetermined clearance with the reverse feeding portion by being projected from a side surface of the second chamber in a horizontal direction. The projected portion is disposed higher than a rotation center of the reverse feeding portion and lower than a top of the reverse feeding portion and is more remote from the first chamber than a rotation center of the feeding member.

Abstract: A developing device includes a developer carrying member, a first chamber, a second chamber, a first feeding member, and a second feeding member. The second feeding member includes first to third spiral portions and a disk portion. The disk portion includes a projected portion. When the disk portion is seen in an axial direction of the second feeding member, on the basis of a line connecting a rotation center of the disk portion and an upstream end portion of the third spiral portion with respect to a feeding direction of the third spiral portion, the projected portion is provided within a range from a position deviated by 90 degrees toward a downstream side with respect to a rotational direction of the disk portion to a position deviated by 30 degrees toward an upstream side with respect to the rotational direction of the disk portion.

Abstract: A developing device includes a developer carrying member, a first chamber, a second chamber, a first feeding member, and a second feeding member. The second feeding member includes first to third spiral portions and a disk portion. The disk portion includes a projected portion. When the disk portion is seen in an axial direction of the second feeding member, on the basis of a line connecting a rotation center of the disk portion and an upstream end portion of the third spiral portion with respect to a feeding direction of the third spiral portion, the projected portion is provided within a range from a position deviated by 90 degrees toward a downstream side with respect to a rotational direction of the disk portion to a position deviated by 30 degrees toward an upstream side with respect to the rotational direction of the disk portion.