JP5268386B2 - Developing device and image forming apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, improved in sealing properties of a magnetic seal for preventing leakage of developer to the outside a housing, while recovering the developer on a developing roller which is not used for the formation of a latent image of a photoreceptor, after development. <P>SOLUTION: The developing device 14 includes: a developing roller 27, which includes a sleeve 26 rotated around an axial line Z to supply toner to a photoreceptor 11, and fixes and supports a magnetic roller 25, having a plurality of roller magnetic pole parts 25M on the inside of the sleeve 26; and a magnetic seal member 29, disposed on both end parts 26a in the axial Z direction of the sleeve 26, with a gap from the circumferential surface of the sleeve 26. The roller magnetic pole part 25M has a support magnetic pole region, in which different polarities are formed alternatingly, and a separation magnetic pole area in which the same polarities are formed adjacent; and the magnetic seal member 29 has different polarities arranged alternately so that the magnetic force of the magnetic pole part of a separation magnetic pole part 29b, opposed to the separation magnetic pole region is larger than that of the magnetic pole part of a support magnetic pole part 29a opposed to the support magnetic pole area. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a developing device that performs development by electrophotography using a developer containing magnetic particles, and in particular, a developing device that prevents the developer from flowing out of a developing area, and a facsimile, printer, and the like equipped with the developing device. The present invention relates to an image forming apparatus.

  The developing device used in the image forming apparatus is for developing the electrostatic latent image formed on the peripheral surface of the photoconductor provided in the image forming apparatus into a toner image, and from the developer storage chamber in the housing. A developing roller is provided for supplying the developer conveyed by the stirring member to the photosensitive member. The developing roller includes a sleeve attached to the housing so as to be rotatable about its axis, and a magnetic roller disposed in the sleeve and fixed to the sleeve. The sleeve has a peripheral surface region that faces the housing and is supplied with the developer, and a peripheral surface region that is exposed outside the housing and faces the developing position. The magnetic roller has a plurality of magnetic poles and is opposed to the inside of the sleeve.

  As the developer, a developer containing magnetic particles is used, such as a one-component developer made of magnetic toner, or a two-component developer made of toner and a magnetic carrier, and the magnetic particles are magnetically passed through a sleeve. By being attracted by the magnetic force of the roller, the developer is carried on the peripheral surface region of the sleeve in the housing. With the rotation of the sleeve, when the peripheral surface area faces the development position facing the photoconductor, the developer carried on the peripheral surface area is supplied to the photoconductor, and is previously applied to the peripheral surface of the photoconductor. A toner image corresponding to the formed electrostatic latent image is formed. A predetermined image is formed on the paper by transferring and fixing the toner image on the paper.

  In the developing device, the magnetic seal member is disposed with a predetermined gap from the peripheral surface of the sleeve so as to face each other at both ends of the peripheral surface region of the sleeve facing the housing (for example, see Patent Document 1 below). . The magnetic seal member is made of, for example, a ferromagnetic material, and magnetic lines of force connecting the magnetic roller in the sleeve and the magnetic seal member are formed at both ends of the sleeve. The agent is prevented from leaking from the both ends of the sleeve to the outside of the housing.

  Normally, when the development is completed, the developer on the peripheral surface of the sleeve that has not been used for forming the latent image on the photoreceptor is collected in the developer storage chamber. In order to collect the developer, the magnetic roller is formed with a separation magnetic pole region that does not generate a magnetic force line with the magnetic seal member or has an extremely small density of the magnetic force lines in a part of the circumferential direction. It is difficult for the developer to be carried on the peripheral surface of the sleeve corresponding to the region. Therefore, after the developer is supplied to the photoreceptor, the sleeve is further rotated, and when the sleeve carrying the unused developer comes to the separation magnetic pole region, the sleeve comes into contact with the blade roller, etc. The developer is peeled off from the sleeve by a roller or the like and collected in the developer storage chamber.

However, since this separation magnetic pole region is formed on the circumferential surface of the sleeve to both ends thereof, no magnetic field lines are formed in the gap formed by the sleeve and the magnetic seal member in the separation magnetic pole region, or the density of the magnetic field lines is low. Since it is extremely small, there is a problem in that it leaks out of the housing from both ends of the separated magnetic pole region.
JP-A-5-297697 (paragraphs [0043] to [0046], FIG. 12)

  The present invention has been made to solve the above-described problems, and the developer on the developing roller that has not been used for forming a latent image on the photoconductor after development is collected, and is also disposed outside the housing. An object of the present invention is to provide a developing device with improved sealing performance of a magnetic seal for preventing the developer from leaking out and an image forming apparatus provided with the developing device.

  In order to achieve the above object, the present invention provides a magnetic roller having a sleeve that rotates about an axis, and a plurality of magnetic pole portions fixedly supported on the inside of the sleeve, and the sleeve at both ends in the axial direction of the sleeve. In the developing device including a magnetic seal member provided with a gap with respect to the peripheral surface, the plurality of magnetic pole portions are formed adjacent to the carrying magnetic pole regions in which different polarities are alternately formed. The magnetic seal member has a plurality of different polarities alternately arranged so as to face the plurality of magnetic pole portions, and faces the carrying magnetic pole portion facing the carrying magnetic pole region and the separation magnetic pole region. A separation magnetic pole portion, and the magnetic force of the separation magnetic pole portion is larger than the magnetic force of the carrier magnetic pole portion.

  According to this configuration, in the gap between the sleeve and the magnetic seal member in the carrier magnetic pole region, the developer is held along each line of magnetic force formed by the magnetic pole in the carrier magnetic pole region and the magnetic pole of the carrier magnetic pole portion. Also, in the gap between the sleeve and the magnetic seal member in the separation magnetic pole region, the magnetic field lines in the separation magnetic pole region are not formed or the density of the magnetic field lines is extremely small, but the magnetic force of the separation magnetic pole part is set larger than the magnetic force of the carrying magnetic pole part. Therefore, the magnetic brush heads are strongly formed by the magnetic lines formed between the adjacent poles of the separation magnetic pole part, and the developer that may leak to the outside due to the magnetic brush heads is blocked. It is done.

  The present invention also provides an image forming apparatus equipped with the developing device having the above-described configuration.

  According to the first aspect of the present invention, in the gap between the sleeve and the magnetic seal member in the carrying magnetic pole region, the developer is held along each magnetic field line formed by the magnetic pole in the carrying magnetic pole region and the magnetic pole in the carrying magnetic pole portion. Is done. Also, in the gap between the sleeve and the magnetic seal member in the separation magnetic pole region, the magnetic field lines in the separation magnetic pole region are not formed or the density of the magnetic field lines is extremely small, but the magnetic force of the separation magnetic pole part is set larger than the magnetic force of the carrying magnetic pole part. Therefore, the magnetic brush heads are strongly formed by the magnetic lines formed between the adjacent poles of the separation magnetic pole part, and the developer that may leak to the outside due to the magnetic brush heads is blocked. It is done. Therefore, in almost the entire region of the separation magnetic pole part and the support magnetic pole part, the magnetic lines of force between the sleeve and the magnetic seal member and the ears of the magnetic brush fill the gap between the sleeve and the magnetic seal member, and the developer is in the sleeve. Outflow from the end to the outside of the developing device can be prevented. Further, the developer on the developing roller that has not been used for forming a latent image on the photoconductor after development can be collected in the housing in the separation magnetic pole region.

  According to the second aspect of the present invention, if the developing device described above is provided, the developer on the developing roller that has not been used for forming a latent image on the photoconductor after development is recovered. The image forming apparatus can be improved in the sealing performance of the magnetic seal for preventing the developer from leaking out of the housing.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. The embodiment of the present invention shows the most preferable form of the invention, and the use of the invention and the terms shown here are not limited thereto.

  FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, an image forming apparatus 1 includes a paper feeding unit 2 disposed in a lower portion of an image forming apparatus main body 1a, and a paper transport unit 3 disposed on the side and above the paper feeding unit 2. The image forming unit 4 disposed above the sheet conveying unit 3, the fixing unit 5 disposed on the discharge side of the image forming unit 4, the image forming unit 4, and the fixing unit 5 The image reading unit 6 is provided above the image reading unit 6.

  The paper feed unit 2 includes a plurality (four in this embodiment) of paper feed cassettes 7 in which paper 9 is stored. The paper 9 is sent from the selected paper feed cassette 7 to the paper transport unit 3, and the paper 9 is surely fed to the paper transport unit 3 one by one. These four paper feed cassettes 7 are configured to be detachable from the image forming apparatus main body 1a.

  The paper 9 fed to the paper transport unit 3 is transported toward the image forming unit 4 via the paper supply path 10. The image forming unit 4 forms a predetermined toner image on the paper 9 by an electrophotographic process, and is a photosensitive member which is an image carrier that is rotatably supported in a predetermined direction (the arrow direction in the drawing). A charging device 12, an exposure device 13, a developing device 14, a transfer device 15, a cleaning device 16, and a charge eliminating device 17 are provided around the photoconductor 11 and along the rotation direction of the photoconductor 11.

  The charging device 12 includes a charging wire to which a high voltage is applied. By applying a predetermined potential to the surface of the photoconductor 11 by corona discharge from the charging wire, the surface of the photoconductor 11 is uniformly charged. It is done. The exposure device 13 irradiates the photoconductor 11 with light based on the image data of the original read by the image reading unit 6, whereby the surface potential of the photoconductor 11 is selectively attenuated, and this photosensitivity is detected. An electrostatic latent image is formed on the surface of the body 11. Next, the developing device 14 attaches toner to the electrostatic latent image to form a toner image on the surface of the photoconductor 11, and the transfer device 15 transfers the toner image on the surface of the photoconductor 11 to the photoconductor 11. The image is transferred to the sheet 9 supplied between the apparatus 15.

  The sheet 9 on which the toner image is transferred is conveyed from the image forming unit 4 toward the fixing unit 5. The fixing unit 5 is disposed on the downstream side of the image forming unit 4 in the sheet conveying direction, and the sheet 9 on which the toner image is transferred in the image forming unit 4 includes a heating roller 18 provided in the fixing unit 5, and The toner image is fixed on the sheet 9 by being sandwiched and heated by the pressure roller 19 pressed against the heating roller 18. Next, the sheet 9 on which the image is formed in the fixing unit 5 from the image forming unit 4 is discharged onto the discharge tray 21 by the discharge roller pair 20. On the other hand, after the transfer, the toner remaining on the surface of the photoconductor 11 is removed by the cleaning device 16, and the residual charge on the surface of the photoconductor 11 is removed by the static eliminator 17. Then, the photoreceptor 11 is charged again by the charging device 12, and image formation is performed in the same manner.

  Next, the developing device will be described. 2 is a cross-sectional side view showing the developing device in the image forming apparatus according to the embodiment of the present invention, and FIG. 3 is a cross-sectional plan view of the developing device shown in FIG. 2 as viewed from above.

  As shown in FIG. 2, the developing device 14 includes a housing 22 that stores the developer, stirring members 23 and 24 that are disposed inside the housing 22 and stir and transport the developer, and supply the developer to the photosensitive member 11. A developing roller 27, a regulating plate 28, and a magnetic seal member 29. The developing roller 27 is disposed extending in the direction of the axis Z (see FIG. 3), and the agitating members 23 and 24 are disposed in parallel to the developing roller 27.

  The agitating members 23 and 24 are arranged at the bottom of the housing 22 and include a support shaft extending in the direction of the axis Z (see FIG. 3) and spiral blades provided around the support shaft, and rotate around the support shaft. Can do. As the agitating members 23 and 24 rotate around their support shafts, the developer circulates between the agitating members 23 and 24 so that the toner and the magnetic carrier are uniformly mixed and supplied to the developing roller 27. .

  The developing roller 27 has a cylindrical shape and is disposed adjacent to the stirring member 24. The developing roller 27 includes a nonmagnetic sleeve 26 and a magnetic roller 25 disposed in the sleeve 26.

  The sleeve 26 forms a peripheral surface region in which approximately half of the circumferential direction is exposed to the outside of the housing 22 and a peripheral surface region that faces the housing 22. In the peripheral surface area exposed to the outside of the housing 22, a developing position D for supplying the developer to the photoconductor 11 is provided facing the photoconductor 11. Further, the sleeve 26 can rotate in the direction of the arrow (counterclockwise) shown in FIG.

  The magnetic roller 25 includes a roller magnetic pole portion 25M and a support body 25a, and is fixedly supported inside the sleeve 26. The support 25a is inserted and fixed in the sleeve 26, and is coaxial with the sleeve 26 and has substantially the same length in the axis Z direction. Around the support body 25a, the roller magnetic pole portion 25M is fixed to the sleeve 26 with a predetermined interval.

  The roller magnetic pole portion 25M has a plurality of magnetic poles, and the magnetic pole portion N2 is adjacent to the magnetic pole portion S1, the magnetic pole portion S3 is adjacent to the magnetic pole portion S3, and the magnetic pole portion is adjacent to the magnetic pole portion S1 in the rotational direction shown in FIG. N4 is provided in close contact with the magnetic pole portion S5. The polarity of each magnetic pole part toward the sleeve 26 is such that the magnetic pole parts N2 and N4 are N poles, the magnetic pole parts S1, S3, and S5 are S poles, and each magnetic pole part has N poles and S poles alternately. Supported to be arranged. Where the N pole and S pole are alternately arranged, a carrier magnetic pole region in which the developer adheres to the circumferential surface of the sleeve 26 is formed by the magnetic carrier of the developer and the magnetic pole of the magnetic pole portion. Further, a magnetic pole part N6 is provided adjacent to the magnetic pole part S5, and a magnetic pole part N7 is provided adjacent thereto. The polarities of the magnetic pole portions N6 and N7 toward the sleeve 26 are both N poles, and the magnetic poles having the same polarity are supported so as to be adjacent to each other. When the adjacent magnetic poles are formed with the same polarity, the magnetic forces are repelled from each other, and a separated magnetic pole region is formed where the magnetic force gradually decreases from the peak position of both magnetic forces and becomes 0 Gauss.

  The regulating plate 28 is disposed above the developing roller 27 in the normal direction of the sleeve 26, and is attached with a predetermined distance from the circumferential surface of the sleeve 26, and regulates the developer on the circumferential surface of the sleeve 26 to a predetermined height. It is.

  The developer conveyed from the stirring member 24 adheres to the circumferential surface of the sleeve 26 by the magnetic force formed by the carrying magnetic pole region of the roller magnetic pole portion 25M. The attached developer is regulated to a certain height by the regulation plate 28 and is carried on the circumferential surface of the sleeve 26. When the developer whose height is restricted is conveyed to the developing position D by the rotation of the sleeve 26 and comes into contact with the photosensitive member 11, only the toner depends on the bias voltage applied to the photosensitive member 11 and the developing roller 27. Supplied to the photoreceptor 11.

  When the sleeve 26 further rotates and the developer that has not been supplied to the photoreceptor 11 reaches the separation magnetic pole region of the magnetic roller 25, the magnetic force directed toward the sleeve 26 is small or substantially zero in the separation magnetic pole region. Due to the gauss, the force of the developer carried on the sleeve 26 is reduced, and the developer is peeled off from the sleeve 26 by a blade roller or the like (not shown) in contact with the sleeve 26, and the stirring member 24 side. The housing 22 is recovered.

  Next, the magnetic seal member 29 will be described. As shown in FIGS. 2 and 3, the magnetic seal member 29 is formed of a magnetic material (for example, a magnet or a ferromagnetic material) and prevents the developer from leaking out of the housing 22 together with the magnetic roller 25. It is. In addition, the magnetic seal member 29 is provided in a semicircular cross section at both ends in the axis Z direction of the sleeve 26, and is opposed to the peripheral surface region of the sleeve 26 in the housing 22 with a certain gap therebetween. The magnetic pole portions S1 and N2 in the carrying magnetic pole region of the roller 25 and the magnetic pole portions N6 and N7 in the separated magnetic pole region are opposed to each other through the sleeve 26.

  The magnetic seal member 29 will be described in detail with reference to FIGS. 4 is a cross-sectional plan view showing the configuration of the magnetic roller and the magnetic seal member in the developing device, and FIG. 5 is a cross-sectional side view showing the configuration of the magnetic roller and the magnetic seal member in the developing device.

  As shown in FIG. 4, the magnetic seal member 29 is arranged with a certain gap with respect to the circumferential surface of the sleeve 26 at the end portion 26 a outside the region carrying the developer used for developing the sleeve 26. Thus, the developer is prevented from leaking from the end portion 26a to the outside of the development area. In the present embodiment, the gap is set to approximately 1 mm, and the magnetic seal member 29 is also disposed at the other end of the sleeve 26 as shown in FIG.

  Therefore, since the magnetic seal member 29 is formed of a magnetic material (for example, a magnet or a ferromagnetic material), development is performed along each magnetic field line formed by the magnetic pole of the magnetic seal member 29 and the magnetic pole of the magnetic roller 25. The agent is retained. In other words, the developer is magnetically sealed in the gap between the circumferential surface of the sleeve 26 and the surface of the magnetic seal member 29 facing the sleeve 26 within the range of the length M shown in FIG. From the outside to the outside of the developing device 14.

  Next, as shown in FIG. 5, the magnetic seal member 29 has a plurality of magnetic poles, and in the clockwise direction shown in FIG. 5, from one end side to the other end side of the arc shape, The magnetic pole portions N are provided in close contact with each other at the same interval. The polarities of the magnetic pole portions toward the magnetic roller 25 are such that each magnetic pole portion N has an N pole and each magnetic pole portion S has an S pole. For example, the circumferential length of the magnetic seal member 29 is 50 mm, and the sizes of the magnetic pole portions S and N are 6 mm in the axial Z direction, 1 mm in the radial direction, and 3 mm in the circumferential direction. The magnetic seal member 29 includes a carrying magnetic pole portion 29a and a separation magnetic pole portion 29b.

  The supporting magnetic pole portion 29a is disposed to face the magnetic pole portions S1 and N2 in the supporting magnetic pole region of the roller magnetic pole portion 25M, and the magnetic force of each magnetic pole portion S and N is approximately 400 gauss. By arranging in this manner, the gap between the sleeve 26 and the magnetic seal member 29 is caused by the magnetic force lines formed by the magnetic pole part N2 and the magnetic pole part S and the magnetic force lines formed by the magnetic pole part S1 and the magnetic pole part N. Retained. The magnetic field lines fill the gap between the sleeve 26 and the magnetic seal member 29 in almost the entire area of the supporting magnetic pole portion 29a, thereby preventing the developer from leaking out of the developing area.

  The separation magnetic pole portion 29b is disposed to face the magnetic pole portions N6 and N7 in the separation magnetic pole region of the roller magnetic pole portion 25M. Therefore, the magnetic pole portions N6 and N7 of the roller magnetic pole portion 25M are opposed to the magnetic pole portions S of the separation magnetic pole portion 29b, and the lines of magnetic force formed between the magnetic pole portions N6 and N7 and the magnetic pole portion S are formed. Along with the developer. However, in the separation magnetic pole region of the roller magnetic pole portion 25M, since the magnetic force toward the separation magnetic pole portion 29b is small or 0 gauss, the magnetic force lines between the roller magnetic pole portion 25M and the magnetic seal member 29 are difficult to be formed. The agent may leak out of the development area. Therefore, the magnetic force of each magnetic pole part S, N of the separation magnetic pole part 29b is set to, for example, approximately 700 Gauss, and the magnetic force of each magnetic pole part S, N of the separation magnetic pole part 29b is made larger than that of the carrying magnetic pole part 29a. The magnetic field lines are increased to form a strong magnetic brush by the magnetic field lines formed by the S pole of the magnetic pole part S adjacent to the separation magnetic pole part 29b and the N pole of the magnetic pole part N. The developer that may leak out is blocked.

  The magnetic seal member 29 holds the developer between the adjacent magnetic pole portions S and N. When the overlap in the axis Z direction between the magnetic seal member 29 and the magnetic roller 25 is reduced and the range M in which the magnetic brush shown in FIG. 4 is formed is set small, the lines of magnetic force between the roller magnetic pole portion 25M and the magnetic seal member 29 are set. On the other hand, the effect of the sealing performance due to the rise of the magnetic brush between the magnetic pole portions S and N of the magnetic sealing member 29 is increased. Therefore, when the magnetic force of each of the magnetic pole portions S and N of the separation magnetic pole portion 29b is made larger than that of the carrying magnetic pole portion 29a, the developer of the magnetic brush becomes stronger, and the developer that may leak to the outside is exposed. Can be dammed up.

  According to the above-described embodiment, the developing device 14 has the sleeve 26 that rotates about the axis Z and supplies the toner to the photoconductor 11, and the magnetic roller including the plurality of roller magnetic pole portions 25 </ b> M inside the sleeve 26. 25, a developing roller 27 that fixes and supports 25, and a magnetic seal member 29 that is disposed at both ends 26a of the sleeve 26 in the axis Z direction with a gap with respect to the circumferential surface of the sleeve 26. The roller magnetic pole portion 25M includes a supporting magnetic pole region in which different polarities are alternately formed and a separation magnetic pole region in which the same polarity is formed adjacent to each other, and the magnetic seal member 29 is arranged in such a manner that different polarities are alternately arranged. The magnetic force of the magnetic pole part of the separation magnetic pole part 29b facing the region is larger than the magnetic force of the magnetic pole part of the carrier magnetic pole part 29a facing the carrier magnetic pole area.

  According to this configuration, the gap between the sleeve 26 and the magnetic seal member 29 in the carrier magnetic pole region of the roller magnetic pole portion 25M is formed by the magnetic pole of the carrier magnetic pole portion 29a and the magnetic pole portions S1 and N2 of the roller magnetic pole portion 25M. The developer is held along each magnetic field line. Further, in the gap between the sleeve 26 and the magnetic seal member 29 in the separation magnetic pole region of the roller magnetic pole portion 25M, the magnetic field lines in the separation magnetic pole region are not formed or the density of the magnetic force lines is extremely small. Since the magnetic force is set to be larger than the magnetic force of the magnetic pole portion of the carrier magnetic pole portion 29a, the magnetic brush heads are strongly formed by the magnetic force lines formed between the different poles adjacent to the separation magnetic pole portion. The developer that may leak to the outside due to the heading is blocked. Accordingly, in almost the entire region of the separation magnetic pole portion 29b and the support magnetic pole portion 29a, the magnetic lines of force between the sleeve 26 and the magnetic seal member 29 and the rise of the magnetic brush fill the gap between the sleeve 26 and the magnetic seal member 29. Further, it is possible to prevent the developer from flowing out from the end portion 26 a of the sleeve 26 to the outside of the developing device 14.

  In the above-described embodiment, the separation magnetic pole region of the magnetic roller 25 has a configuration in which the magnetic pole part N6 and the magnetic pole part N7 are provided in close contact with each other. However, the present invention is not limited to this, and the magnetic pole part N6 and the magnetic pole part N7 A space may be provided and separated. In this case, the same effect as described above can be obtained.

  INDUSTRIAL APPLICABILITY The present invention can be used in a developing device that performs development by electrophotography using a developer containing magnetic particles, and an image forming apparatus such as a facsimile and a printer equipped with the developing device.

FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. These are sectional side views showing a developing device in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a cross-sectional plan view showing a developing device in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a cross-sectional plan view showing a magnetic roller and a magnetic seal member of the developing device in the image forming apparatus according to the embodiment of the present invention. These are sectional side views showing a magnetic roller and a magnetic seal member of the developing device in the image forming apparatus according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper feeding part 3 Paper conveyance part 4 Image forming part 5 Fixing part 6 Image reading part 11 Photoconductor 14 Developing apparatus 22 Housing 23, 24 Stirring member 25 Magnetic roller 25a Support body 25M Roller magnetic pole part 26 Sleeve 27 Development Roller 28 Restriction plate 29 Magnetic seal member 29a Carrying magnetic pole part 29b Separating magnetic pole part

Claims (2)

A magnetic roller having a sleeve that rotates about an axis, and a plurality of magnetic pole portions fixedly supported inside the sleeve; and a gap between the sleeve and the circumferential surface of the sleeve at both ends in the axial direction. A developing device comprising a magnetic seal member,
The plurality of magnetic pole portions include a supporting magnetic pole region in which different polarities are alternately formed and a separation magnetic pole region in which the same polarity is formed adjacent to each other,
The magnetic seal member has a plurality of different polarities alternately arranged facing the plurality of magnetic pole portions, and includes a supporting magnetic pole portion facing the supporting magnetic pole region and a separation magnetic pole portion facing the separation magnetic pole region, The developing device according to claim 1, wherein the magnetic force of the separation magnetic pole part is larger than the magnetic force of the carrier magnetic pole part.   An image forming apparatus on which the developing device according to claim 1 is mounted.

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