Developing apparatus and image forming apparatus equipped therewith

Abstract

To provide a developing apparatus that can achieve good developer release properties while suppressing an increase in size, and an image forming apparatus equipped therewith. [Solution] The magnetic member is fixed non-rotatably inside the developing sleeve and includes a plurality of magnetic poles arranged along the rotational direction of the developing sleeve. The magnetic poles include a main pole facing the image carrier and a peeling pole positioned adjacent to the main pole downstream in the rotational direction of the developing sleeve, which peels off the developer supported on the developer carrier. The peak position of the magnetic flux density of the main pole is located below a horizontal line passing through the rotational center of the developing sleeve, and when viewed from the axial direction, the angle of the line extending from the peak position of the magnetic flux density of the main pole to the rotational center of the developing sleeve with respect to the horizontal line passing through the rotational center of the developing sleeve is between 40 degrees and 80 degrees.

Description

Technical Field

[0006] , , , ,

[0001] The present invention relates to a developing device and an image forming apparatus including the same.

Background Art

[0002] A conventional developing device includes a developing container, a stirring and conveying member, a developer carrier, and a seal roll, and develops an electrostatic latent image formed on an image carrier into a toner image. The developing container has a conveying chamber and houses a two-component developer including a carrier and toner. The stirring and conveying member is rotatably supported in the conveying chamber and conveys the developer in the conveying chamber while stirring it. <00资源不足00011> The developer carrier is rotatably supported by the developing container and supports the developer in the conveying chamber on its surface. Supply of the developer to the developer carrier and recovery of the developer from the developer carrier are performed in the conveying chamber.

[0004] The developer carrier has a rotatable cylindrical developing sleeve and a magnet member. The magnet member is fixedly provided inside the developing sleeve in a non-rotatable manner and includes a plurality of magnetic poles arranged along the rotation direction of the developing sleeve. The magnetic poles include a main pole facing the image carrier and a peeling pole. The peeling pole is arranged adjacent to the main pole on the downstream side in the rotation direction of the developing sleeve and includes a peeling pole for peeling the developer carried on the developer carrier. The seal roll is arranged to face the peeling pole and promotes peeling of the developer. Thereby, the developer peeled from the developing roller is recovered into the stirring chamber.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, conventional developing equipment requires extra space for a sealing roll. This could potentially lead to larger developing equipment.

[0007] In view of the above problems, the present invention aims to provide a developing apparatus that can achieve good developer removal while suppressing an increase in size, and an image forming apparatus equipped therewith. [Means for solving the problem]

[0008] To achieve the above objective, the first configuration of the present invention is a developing apparatus comprising a developing container, a first stirring and conveying member, a second stirring and conveying member, and a developer carrier, for developing an electrostatic latent image formed on an image carrier into a toner image. The developing container has a first conveying chamber and a second conveying chamber positioned above the first conveying chamber with a partition in between, and contains a two-component developer including a carrier and toner. The first stirring and conveying member is rotatably supported within the first conveying chamber and conveys the developer in the first conveying chamber in a first direction while stirring. The second stirring and conveying member is rotatably supported within the second conveying chamber parallel to the first stirring and conveying member and conveys the developer in the second conveying chamber in a second direction opposite to the first direction while stirring. The developer carrier is rotatably supported within the developing container and carries the developer in the second conveying chamber on its surface. A regulating blade is positioned opposite the developer carrier and regulates the thickness of the developer layer on the developer carrier. The developer carrier comprises a rotatable cylindrical developing sleeve and a magnetic member. The magnetic member is fixed non-rotatably inside the developing sleeve and includes a plurality of magnetic poles arranged along the direction of rotation of the developing sleeve. The magnetic poles include a main pole facing the image carrier and a peeling pole positioned adjacent to the main pole downstream in the direction of rotation of the developing sleeve, for peeling off the developer carried on the developer carrier. The peak position of the magnetic flux density of the main pole is located below a horizontal line passing through the center of rotation of the developing sleeve, and, viewed from the axial direction, the angle of the line extending from the peak position of the magnetic flux density of the main pole to the center of rotation of the developing sleeve with respect to the horizontal line passing through the center of rotation of the developing sleeve is between 40 and 80 degrees. [Effects of the Invention]

[0009] According to the first configuration of the present invention, it is possible to provide a developing apparatus that can achieve good developer peelability while suppressing an increase in size, and an image forming apparatus equipped therewith. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic cross-sectional view showing the overall configuration of the image forming apparatus 100 equipped with the developing devices 3a to 3d of the present invention. [Figure 2] Side cross-sectional view showing the structure of the stirring section of a developing apparatus 3a according to one embodiment of the present invention. [Figure 3] A longitudinal cross-sectional view of the developing apparatus 3a of this embodiment, cut in a direction perpendicular to the longitudinal direction. [Figure 4] A longitudinal cross-sectional view of a modified developing apparatus 3a according to this embodiment, cut in a direction perpendicular to the longitudinal direction. [Modes for carrying out the invention]

[0011] [1. Configuration of the image forming apparatus] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic cross-sectional view of an image forming apparatus 100 equipped with developing devices 3a to 3d of the present invention. For convenience of explanation, the vertical direction is defined as the up-down direction (Z1-Z2 direction) when the image forming apparatus 100 is in a usable installation state (as shown in Figure 1). The front-to-back direction (Y1-Y2 direction) is defined with the front side of the image forming apparatus 100 shown in Figure 1 being the front. The left-to-right direction (X1-X2 direction) is defined with reference to the front of the image forming apparatus 100 in its installed state. In this embodiment, the left-to-right direction (X1-X2 direction) is orthogonal to the up-to-down direction (Z1-Z2 direction) and the front-to-back direction (Y1-Y2 direction).

[0012] The image forming apparatus 100 is a tandem-type color printer. Inside the main body of the image forming apparatus 100, four image forming units Pa, Pb, Pc, and Pd are arranged in the order Pd to Pa from the upstream side in the transport direction (right side in Figure 1). These image forming units Pa to Pd are provided to correspond to images of four different colors (yellow, cyan, magenta, and black), and sequentially form images of yellow, cyan, magenta, and black through the processes of charging, exposure, development, and transfer, respectively.

[0013] Each image forming section Pa to Pd is equipped with a photosensitive drum (image carrier) 1a, 1b, 1c, and 1d, respectively, which carry a visible image (toner image) of each color. In addition, an intermediate transfer belt 8, which rotates clockwise in Figure 1, is provided adjacent to each image forming section Pa to Pd.

[0014] When image data is input from a higher-level device such as a personal computer, first, the surfaces of the photoreceptor drums 1a to 1d are uniformly charged by the charging devices 2a to 2d. Next, the exposure device 5 irradiates the surfaces of the photoreceptor drums 1a to 1d with light according to the image data, forming electrostatic latent images on each of the photoreceptor drums 1a to 1d corresponding to the image data.

[0015] The developing units 3a to 3d are filled with predetermined amounts of a two-component developer (hereinafter simply referred to as "developer") containing yellow, cyan, magenta, and black toners supplied from toner containers (not shown) and magnetic carriers. The developing units 3a to 3d supply the toner from the developer onto the photoreceptor drums 1a to 1d, where it adheres electrostatically. This forms a toner image corresponding to the electrostatic latent image formed by exposure from the exposure unit 5.

[0016] An endless intermediate transfer belt 8 is stretched over a drive roller 10 and a driven roller 11. The drive roller 10 is rotated by a motor (not shown), causing the intermediate transfer belt 8 to circulate in the clockwise direction shown in Figure 1.

[0017] The photoreceptor drums 1a to 1d are arranged adjacent to each other along the conveyance direction above the intermediate transfer belt 8 at Z1. Also, the photoreceptor drums 1a to 1d are each in contact with the intermediate transfer belt 8.

[0018] The primary transfer rollers 6a to 6d face the photoreceptor drums 1a to 1d respectively with the intermediate transfer belt 8 interposed therebetween. The primary transfer rollers 6a to 6d are each pressed against the intermediate transfer belt 8 to form a primary transfer portion together with the photoreceptor drums 1a to 1d. In these primary transfer portions, the toner images are transferred onto the intermediate transfer belt 8.

[0019] An electric field is applied at a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photoreceptor drums 1a to 1d by the primary transfer rollers 6a to 6d, and the yellow, cyan, magenta, and black toner images on the photoreceptor drums 1a to 1d are primarily transferred onto the intermediate transfer belt 8. Toner and the like remaining on the surfaces of the photoreceptor drums 1a to 1d after the primary transfer are removed by the cleaning devices 7a to 7d.

[0020] The transfer paper P onto which the toner image is to be transferred is housed in a paper cassette 16 arranged at the lower part inside the image forming apparatus 100. The transfer paper P is conveyed to the nip portion (secondary transfer nip portion) between the secondary transfer roller 9 provided adjacent to the intermediate transfer belt 8 and the intermediate transfer belt 8 at a predetermined timing via the paper feed roller 12a and the registration roller pair 12b. The transfer paper P onto which the toner image has been secondarily transferred is conveyed to the fixing unit 13.

[0021] The transfer paper P conveyed to the fixing unit 13 is heated and pressurized by passing through the nip portion between the fixing belt and the pressure roller, and the toner image is fixed on the surface of the transfer paper P, forming a predetermined full-color image. The transfer paper P on which the full-color image has been formed is discharged to the discharge tray 17 by the discharge roller pair 15 (either as it is or after being diverted to the reverse conveyance path 18 and having images formed on both sides).

[0022] [2. Detailed Configuration of Developing Device] Figure 2 is a longitudinal cross-sectional view showing the structure of the stirring section of a developing device 3a according to one embodiment of the present invention, which is mounted on an image forming apparatus 100. Here, we will describe the developing device 3a located in the image forming section Pa of Figure 1, but the configurations of the developing devices 3b to 3d located in the image forming sections Pb to Pd are basically the same, so their description will be omitted. Also, in Figure 2, for the sake of explanation, the position of the developing roller 20 is shown shifted above the first transport chamber 22b.

[0023] As shown in Figure 2, the developing apparatus 3a comprises a developing roller (developer carrier) 20, a first spiral (first agitation and conveying member) 43, a second spiral (second agitation and conveying member) 44, and a developing container 22. The developing container 22 has a first conveying chamber 22b and a second conveying chamber 22c located above the first conveying chamber 22b (Z1) with a partition 22a in between, and contains a two-component developer including a carrier and toner. The developing container 22 also forms the outer casing of the developing apparatus 3a and has a first connecting section 22d and a second connecting section 22e.

[0024] More specifically, the first transport chamber 22b and the second transport chamber 22c contain a two-component developer including a magnetic carrier and toner. The developing container 22 also rotatably holds the first spiral 43, the second spiral 44, and the developing roller 20.

[0025] The partition 22a extends in the longitudinal direction of the developing container 22 and divides the first transport chamber 22b and the second transport chamber 22c so that they are arranged in parallel vertically (Z1-Z2) (see Figure 3). The first connecting section 22d and the second connecting section 22e are formed on one and the other side (downstream side in the A1 direction and downstream side in the A2 direction) of the partition 22b, respectively. The first connecting section 22d connects the downstream ends of the first transport chamber 22b and the second transport chamber 22c in the A1 direction (first direction). The second connecting section 22e connects the downstream ends of the first transport chamber 22b and the second transport chamber 22c in the A2 direction (second direction). The developer circulates through the first transport chamber 22b, the first connecting section 22d, the second transport chamber 22c, and the second connecting section 22e.

[0026] The first spiral 43 is rotatably supported within the first transport chamber 22b and transports the developer in the first transport chamber 22b in the A1 direction (first direction) while agitating it. The first spiral 43 has a rotating shaft 43b rotatably supported by the developing container 22 and a first helical blade 43a. The first helical blade 43a is integrally provided with the rotating shaft 43b and is formed spirally at a constant pitch in the axial direction of the rotating shaft 43b. The first spiral 43 rotates in a predetermined direction (counterclockwise direction in Figure 3) by a drive mechanism (not shown). By rotating in the predetermined direction, the first helical blade 43a transports the developer in the first transport chamber 22b in the A1 direction (one side in the axial direction of the developing roller 20) while agitating it.

[0027] Furthermore, a toner supply port 23 for supplying toner to the developing container 22 is provided at the end face in direction A2 of the first transport chamber 22b. A toner supply path 24 connected to a toner container (not shown) is connected to the toner supply port 23. The rotating shaft 43b passes through the toner supply port 23 and is positioned within the toner supply path 24. A supply blade 43c, which is spirally formed at a constant pitch in the axial direction of the rotating shaft 43b, is integrally formed on the portion of the rotating shaft 43b positioned within the toner supply path 24. The supply blade 43c is formed by spiral blades that face the same direction (are in the same phase) as the first spiral blade 43a. The supply blade 43c is formed with a smaller pitch and a smaller diameter compared to the first spiral blade 43a.

[0028] The second spiral 44 is rotatably supported in the second transport chamber 22c parallel to the first spiral 43, and transports the developer in the second transport chamber 22c in the A2 direction (second direction), which is opposite to the A1 direction (first direction), while agitating it. The second spiral 44 has a rotating shaft 44b that is rotatably supported in the developing container 22 parallel to the rotating shaft 43b, and a second helical blade 44a. The second helical blade 44a is integrally mounted on the rotating shaft 44b and is formed in a spiral shape with blades that face in the opposite direction (opposite phase) to the first helical blade 43a. The second spiral 43 rotates in a predetermined direction (counterclockwise direction in Figure 3) by a drive mechanism (not shown). The second helical blade 44a rotates in the same direction as the first helical blade 43a, supplying the developer to the developing roller 20 while agitating and conveying the developer in the second transport chamber 22c in the A2 direction (opposite to the A1 direction).

[0029] The first spiral 43 and the second spiral 44 agitate the developer, causing the toner in the developer to be charged to a predetermined level. This holds the toner in the carrier. As the first spiral 43 and the second spiral 44 rotate, the developer is transported from one of the connecting parts (first connecting part 22d) in the partition section 22b to the second spiral 44. The developer is also transported from the other connecting part (second connecting part 22e) to the first spiral 43 and circulates between the first transport chamber 22b and the second transport chamber 22c. The developer is then supplied from the second spiral 44 to the developing roller 20, and a magnetic brush is formed on the developing roller 20.

[0030] The developing roller 20 (developer carrier) is rotatably supported in the developing container 22 and carries the developer in the second transport chamber 22c on its surface. The developing roller 20 (developer carrier) has a rotatable cylindrical developing sleeve 20a and a magnetic member 20b. The magnetic member 20b is fixed non-rotatably inside the developing sleeve 20a and includes multiple magnetic poles arranged along the rotation direction of the developing sleeve. The developing sleeve 20a rotates in the direction of the arrow in Figure 3 (counterclockwise) by a drive mechanism (not shown). A developing voltage, obtained by superimposing an AC voltage on a DC voltage, is applied to the developing sleeve 20a. The configuration of the developing roller 20 (developer carrier) will be described in detail later.

[0031] The developer in the first transport chamber 22b is agitated and transported in the A1 direction (towards the first communication section 22d) by the first spiral 43, and gradually accumulates on one side of the first transport chamber 22b. On one side of the first transport chamber 22b, the developer is pushed by the subsequent developer and pushed up to the second transport chamber 22c via the first communication section 22d. The developer in the second transport chamber 22c is supplied to the developing roller 20 while being agitated and transported in the A2 direction (towards the second communication section 22e) by the second spiral 44. The developer that has been transported to the other side of the second transport chamber 22c falls into the first transport chamber 22b via the second communication section 22e.

[0032] [3. Detailed configuration of the magnetic pole component] Figure 3 is a longitudinal cross-sectional view (cross-sectional view taken along the XX' arrow in Figure 2) of the developing apparatus 3a of this embodiment, cut in a direction perpendicular to the longitudinal direction. The regulating blade 27 is attached to the developing container 22. More specifically, the regulating blade 27 is attached along the longitudinal direction of the developing roller 20 (the direction perpendicular to the plane of the paper in Figure 3).

[0033] A small gap (regulating gap) is provided between the tip of the regulating blade 27 and the outer surface of the developing roller 20, forming a regulating section. As the developing sleeve 20a rotates, the developer (magnetic brush) passes through the regulating section, thereby regulating the thickness of the developer layer supported on the surface of the developing roller 20. In this embodiment, a magnetic blade made of stainless steel (SUS430) is used as the regulating blade 27.

[0034] The magnetic pole member 20b of the developing roller 20 includes a plurality of magnetic poles N1, S2, N2, S1, and N3 arranged along the rotational direction of the developing sleeve 20a (counterclockwise direction in Figure 3). The magnetic poles N1, S2, N2, S1, and N3 indicate the peak positions of the magnetic flux density in the circumferential direction of the magnetic pole member 20b. In this embodiment, the magnetic pole member 20b consists of five poles, including a regulating pole (pumping pole) N1, transport poles N2 and S2, a main pole S1, and a peeling pole N3. The regulating pole (pumping pole) N1 is positioned in the region (regulating section) facing the regulating blade 27. In this embodiment, the regulating pole N1 also serves as a pumping pole that pumps the developer onto the developing roller 20.

[0035] The main electrode S1 faces the photosensitive drum (image carrier) 1a. More specifically, the main electrode S1 is positioned in the region (development region) facing the photosensitive drum (image carrier) 1a. The peeling electrode N3 is positioned adjacent to the main electrode S1 and downstream of the developing sleeve 20a in the rotational direction, and peels off the developer carried on the developing roller (developer carrier) 20.

[0036] Furthermore, the transport poles N2 and S2 are positioned between the regulating pole (pushing pole) N1 and the main pole S1. In this embodiment, the magnetic pole member 20b has a 5-pole configuration. When a driving force is input to the developing device 3a, the developing sleeve 20a rotates, but the magnetic member 20b does not rotate.

[0037] The developing device 3a supplies developer from the second spiral 44 in the second transport chamber 22c to the developing roller 20. The developer that has passed through the developing area and consumed toner during development is then collected in the second transport chamber 22c where the second spiral 44 is located.

[0038] More specifically, a magnetic field is generated in an attractive direction between the regulating pole N1 of the magnetic member 20b and the regulating blade 27, thereby forming a magnetic brush with a continuous layer of developer between the regulating blade 27 and the developing roller 20. The magnetic brush passes over the regulating blade 27 (regulating section), thereby restricting the layer thickness to a desired height.

[0039] As the developing sleeve 20a rotates further counterclockwise, the magnetic brush is subjected to a magnetic field along the outer surface of the developing sleeve 20a by the transport poles S2 and N2. Additionally, the magnetic brush is subjected to a magnetic field that attracts it to the photoreceptor drum 1a by the main pole S1. This causes the magnetic brush to contact the surface of the photoreceptor drum 1a and develop the electrostatic latent image. Furthermore, any toner not used for development is collected by the magnetic brush on the developing sleeve 20a.

[0040] As the developing sleeve 20a rotates further counterclockwise, the magnetic brush detaches from the developing roller 20 due to the repulsive magnetic field between the peeling electrode N3 and the regulating electrode (pumping electrode) N1, and is collected in the second transport chamber 22c. The collected toner is agitated and transported by the second spiral 44. The magnetic brush is then formed again on the developing sleeve 20a by the magnetic field of the regulating electrode (pumping electrode) N1.

[0041] In this embodiment, the developing apparatus 3a has the second transport chamber 22c positioned above the first transport chamber 22b at Z1. That is, the first transport chamber 22b and the second transport chamber 22c are positioned vertically. This allows the developing apparatus 3a to be miniaturized horizontally (X1-X2). In the image forming apparatus 100, the four developing apparatuses 3a to 3d are arranged horizontally (X1-X2), so by miniaturizing the developing apparatuses 3a to 3d horizontally (X1-X2), the image forming apparatus 100 can be miniaturized horizontally (X1-X2).

[0042] Furthermore, the rotation center P3 of the developing roller 20 is positioned in the vertical direction (Z1-Z2) between the center P2 of the rotation axis 44b of the second spiral 44 and the center P1 of the rotation axis 43b of the first spiral 43. By positioning the rotation center P3 of the developing roller 20 below the center P2 of the rotation axis 44b of the second spiral 44 (Z2), the developing apparatus 3a can be made smaller in the vertical direction as well.

[0043] Furthermore, the arrangement of the developing roller 20 can be changed circumferentially with respect to the photoreceptor drum 1a. When viewed from the axial direction, moving the developing roller 20 clockwise B1 relative to the photoreceptor drum 1a reduces the angle θ of the straight line L2 with respect to the straight line L1. On the other hand, when viewed from the axial direction, moving the developing roller 20 counterclockwise B2 relative to the photoreceptor drum 1a increases the angle θ of the straight line L2 with respect to the straight line L1. Here, the straight line L1 is a horizontal (X1-X2) straight line passing through the rotation center P3 of the developing sleeve 20a. The straight line L2 is a straight line extending from the peak position of the magnetic flux density of the main pole S1 to the rotation center P3 of the developing sleeve 20a.

[0044] In this embodiment, the angle θ of the straight line L2 with respect to the straight line L1 is preferably 40 degrees or more and 80 degrees or less. When the developing roller 20 is moved circumferentially relative to the photoreceptor drum 1a so that the angle θ of the straight line L2 with respect to the straight line L1 is 40 degrees or more, the developing roller 20 is positioned close to directly above the rotation center P4 of the photoreceptor drum 1a (on the B2 side). This makes it possible to miniaturize the developing device 3a in the horizontal direction (X1-X2). In addition, it is possible to secure space for a sensor that detects toner density. In this case, it is preferable that the sensor that detects toner density be positioned between the intermediate transfer belt 8 and the outer wall of the first transport chamber 22b, in a range that moves from directly below the outer wall of the first transport chamber 22b toward the photoreceptor drum 1a side X2.

[0045] Furthermore, when the developing roller 20 is moved circumferentially relative to the photoreceptor drum 1a so that the angle θ of the straight line L2 with respect to the straight line L1 is less than 80 degrees, the developing roller 20 is positioned away from directly above the rotation center P4 of the photoreceptor drum 1a (towards B1). This allows the developing device 3a to be miniaturized in the vertical direction (Z1-Z2). In addition, the area above Z1 of the photoreceptor drum 1a is left open, and the irradiation area of ​​the laser light C irradiated from the scanning device 5 can be secured on the photoreceptor drum 1a. Thus, it is possible to provide a developing device 3a and an image forming apparatus 100 equipped therewith that can achieve good developer peelability while suppressing an increase in size.

[0046] The peak position of the magnetic flux density of the peeling electrode N3 is opposite the outer wall of the first transport chamber 22b. The outer wall of the first transport chamber 22b surrounds the first spiral (first stirring transport member) 43 and includes a partition 22a. In this embodiment, the peak position of the magnetic flux density of the peeling electrode N3 is located below Z2 above the upper surface of the partition 22a, but it may also be located above Z1 above the upper surface of the partition 22a. As a result, the separation (peeling) of the developer from the developing roller 20 takes place at the lower part of the second spiral 44 in the second transport chamber 22c. At this time, the developer separated from the developing roller 20 is collected in the area of ​​the second transport chamber 22c that is filled with developer. Therefore, toner scattering from the gap between the developing roller 20 and the developing container 22 can be effectively suppressed.

[0047] Furthermore, viewed from the axial direction, the intersection point P6 of the perpendicular line extending perpendicularly from the center P1 of the rotation axis 43b of the first spiral (first stirring and conveying member) 43 to the straight line L1 is closer to the rotation center P3 of the developing sleeve 20 than the intersection point P5 of the perpendicular line extending perpendicularly from the center P2 of the rotation axis 44b of the second spiral (second stirring and conveying member) 44 to the straight line L1. By arranging the first spiral (first stirring and conveying member) 43 and the developing sleeve 20 closer together in the horizontal direction (Y1-Y2), the developing device 3a can be miniaturized in the horizontal direction (X1-X2).

[0048] Furthermore, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention. Figure 4 is a longitudinal cross-sectional view of a modified developing apparatus 3a according to this embodiment. In the above embodiment, the supply of developer to the developing roller (developer carrier) 20 and the collection of developer from the developing roller (developer carrier) 20 were performed in the second transport chamber 22c, but this may also be performed in the first transport chamber 22b. In this case, the developer is supplied from the first spiral 43 to the developing roller 20. In addition, it is preferable that the peak position of the magnetic flux density of the peeling electrode N3 faces the outer wall of the first transport chamber 22b.

[0049] Furthermore, in the above embodiment, the magnetic pole width of the regulating pole N1 was made larger so that it could also be used as the pumping pole. However, the pumping pole may be provided separately on the upstream side of the regulating pole N1 with respect to the rotation direction of the developing roller 20. In addition, although two transport poles N2 and S2 were arranged in the above embodiment, one or more transport poles may be arranged.

[0050] Furthermore, the present invention is not limited to direct transfer type color printers as shown in Figure 1, but is also applicable to intermediate transfer type color printers equipped with an intermediate transfer belt and a secondary transfer roller instead of the transport belt 8, and to various image forming devices equipped with a developing device including a first transport chamber and a second transport chamber located above the first transport chamber, such as digital or analog monochrome copiers, color copiers, and facsimile machines. [Industrial applicability]

[0051] The present invention is applicable to a developing apparatus having a first transport chamber and a second transport chamber positioned above the first transport chamber. By utilizing the present invention, it is possible to provide a developing apparatus that can achieve good developer release properties without increasing the size of the developing apparatus, and an image forming apparatus equipped therewith. [Explanation of Symbols]

[0052] 3a~3d developing device 20. Developing roller (developer carrier) 20a developing sleeve 20b Magnetic component 22 Developing container 22a Partition 22b 1st transfer room 22c Second transport room 22d 1st communication part 22e 2nd communication part 23 Toner refill port 27 Regulatory Blade 43. First spiral (first stirring and conveying member) 44. Second spiral (second stirring and conveying member) 43a First spiral blade 44a Second spiral blade 43b, 44b Rotation axis 100 Image forming apparatus N1 Regulating electrode (pumping electrode) S1 main pole N2, S2 transport poles N3 peeling electrode P1, P2 center P3, P4 rotation centers

Claims

1. A developing container comprising a first transport chamber and a second transport chamber positioned above the first transport chamber, separated by a partition, and containing a two-component developer including a carrier and toner, A first stirring and conveying member is rotatably supported within the first conveying chamber and conveys the developer in the first conveying chamber in a first direction while stirring it. A second stirring and conveying member is rotatably supported in the second conveying chamber parallel to the first stirring and conveying member, and conveys the developer in the second conveying chamber in a second direction opposite to the first direction while stirring it, A developer carrier that is rotatably supported in the developing container and carries the developer in the second transport chamber on its surface, A developing apparatus comprising, which develops an electrostatic latent image formed on an image carrier into a toner image, The supply of the developer to the developer carrier and the recovery of the developer from the developer carrier are performed in the second transport chamber. The developer carrier is A rotatable cylindrical developing sleeve, The magnetic member includes a plurality of magnetic poles fixed non-rotatably inside the developing sleeve and arranged along the direction of rotation of the developing sleeve, The aforementioned magnetic poles are The main pole opposite the image carrier, The main electrode and a peeling electrode, which is positioned adjacent to the main electrode and the developing sleeve in the rotational direction, and peels off the developer supported on the developer carrier, are included. The peak position of the magnetic flux density of the main pole is located below a horizontal line passing through the rotation center of the developing sleeve. A developing apparatus in which, when viewed from the axial direction, the angle between the straight line extending from the peak position of the magnetic flux density of the main pole to the center of the rotation axis of the developing sleeve and a horizontal straight line passing through the center of the rotation axis of the developing sleeve is 40 degrees or more and 80 degrees or less.

2. The developing apparatus according to claim 1, wherein the peak position of the magnetic flux density of the peeling electrode faces the outer wall of the first transport chamber.

3. The developing apparatus according to claim 1 or 2, wherein, when viewed from the axial direction, the intersection of a perpendicular line extending perpendicularly from the center of the rotation axis of the first stirring and conveying member through a horizontal line passing through the rotation center of the developing sleeve is closer to the rotation center of the developing sleeve than the intersection of a perpendicular line extending perpendicularly from the center of the rotation axis of the second stirring and conveying member through a horizontal line passing through the rotation center of the developing sleeve.

4. An image forming apparatus comprising the developing apparatus according to claim 1 or claim 2.

Images