JP2007322775A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device in which a cost reduction is achieved and to provide an image forming apparatus. <P>SOLUTION: The developing device 34 includes: a developing device main body 60; a magnetic force generating means 95 disposed in the developing device main body 60; and a plurality of rotation members disposed in the developing device main body 60 such that they are freely rotated and their peripheries are shielded by the magnetic force generating means 95. The magnetic force generating means 95 has a magnet roll 82, and a magnetic plate 94 disposed in the range of the magnetic force of the magnet roll 82. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, or a facsimile, and a developing device used in these image forming apparatuses.

  2. Description of the Related Art An electrophotographic image forming apparatus applied to a printer, a copying machine, or the like is known that includes a developing device filled with a developer. This type of developing device is provided with a plurality of rotating members such as a developing roll for developing the latent image formed on the photosensitive member with a developer and a conveying means for stirring and conveying the developer in the developing device main body. . These rotating members are rotatably supported by the developing device main body, and there is a problem that the developer leaks from the engaging portion between the developing device main body and the rotating member to the outside of the developing device. Therefore, a bearing device for a developing device is known that includes a magnetic plate that sandwiches an annular magnet for forming a magnetic seal (for example, Patent Document 1).

JP 2000-112228 A

  However, in the above prior art, since the seal member and the magnetic plate corresponding to each rotating member are provided, there is a problem that the number of parts increases and costs increase.

  An object of the present invention is to provide a developing device and an image forming apparatus that solve the above-mentioned conventional problems and realize reduction in the number of parts and cost.

  In order to achieve the above object, the first feature of the present invention is that a developing device main body, a magnetism generating means provided in the developing device main body, a rotation device provided rotatably in the developing device main body, The developing device has a plurality of rotating members whose outer periphery is sealed by the magnetism generating means. Therefore, the leakage of the developer from the bearing portions of the plurality of rotating members is prevented, and the number of parts and the cost are reduced.

  Preferably, the magnetism generating means includes a magnet and a magnetic plate arranged so as to be located in a range where the magnetic force of the magnet reaches.

  Suitably, the said magnetic board is arrange | positioned so that it may adjoin to at least one part of the outer periphery of these rotary members.

  Preferably, at least one of the plurality of rotating members is a developing roll that develops a latent image with a developer in the developing device main body.

  Preferably, the developing roll includes a magnet roll having a plurality of magnetic poles, and the magnet includes the magnet roll.

  Preferably, at least one of the plurality of rotating members is an agitating and conveying member that conveys and agitates the developer in the developing device main body.

  The second feature of the present invention is that it includes a photoconductor on which a latent image is formed, and a developing device that develops the latent image formed on the photoconductor with a developer. An image forming apparatus comprising: an apparatus main body; a magnetism generating means provided in the developing apparatus main body; and a plurality of rotating members rotatably provided in the developing apparatus main body and having outer circumferences sealed by the magnetism generating means. is there.

  According to the present invention, since the outer periphery of the plurality of rotating members is sealed by the magnetic generating means, leakage of the developer is prevented without providing the magnetic generating means at the bearing portions of each of the plurality of rotating members. Cost reduction can be realized.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12. A discharge unit 14 for discharging a sheet on which an image has been formed is provided on the image forming apparatus main body 12. An image forming unit 16 and a sheet supply device 18 are disposed.

  The image forming unit 16 is of an electrophotographic type that forms a color image, and includes four process cartridges 20Y, 20M, 20C, and 20B that are detachably attached to the image forming apparatus body 12, and process cartridges 20Y, 20M, and 20C. 20B, an optical writing device 24 that writes an electrostatic latent image on the photosensitive members 22Y, 22M, 22C, and 22B, respectively, and a developer image formed on the photosensitive members 22Y, 22M, 22C, and 22B, onto a sheet. The image forming apparatus includes a transfer device 26 and a fixing device 28 that fixes the developer image transferred onto the sheet by the transfer device 26 onto the sheet.

  The process cartridge 20Y is for yellow, the process cartridge 20M is for magenta, the process cartridge 20C is for cyan, and the process cartridge 20B is for black. In the image forming apparatus main body 12, the process cartridges are arranged in the vertical direction in the order of, for example, the process cartridge 20Y, the process cartridge 20M, the process cartridge 20C, and the process cartridge 20B from the top. Although the process cartridges are different in the color of the developer to be used, the apparatus configuration is the same. Therefore, hereinafter, the process cartridge 20 will be collectively referred to.

  The process cartridge 20 includes a process cartridge main body 30, and the process cartridge main body 20 includes a photoconductor 22, a charging device 32 having a charging roll for uniformly charging the photoconductor 22, and the charging device 32. A developing device 34 for developing the latent image charged by the optical writing device 24 on the photosensitive member 22 with the developer, and the developer remaining on the photosensitive member 22 after the transfer of the developer image by the transfer device 26. A cleaning device 36 for removal is disposed.

  The optical writing device 24 is composed of, for example, a laser exposure device, and laser light corresponding to a yellow image is applied to the photoconductor 22Y provided in the process cartridge 20Y, and laser corresponding to a magenta image is applied to the photoconductor 22M provided in the process cartridge 20M. Laser light corresponding to the cyan image is emitted to the photosensitive member 22C provided in the process cartridge 20C, laser light corresponding to the black image is emitted to the photosensitive member 22B provided in the process cartridge 20B, and each photosensitive member 22 is statically irradiated. Write an electrostatic latent image.

  The transfer device 26 includes two primary intermediate transfer members 38 and 40 to which the developer image formed on the photosensitive member 24 of each process cartridge 20 is transferred, and the developer transferred to the primary intermediate transfer members 38 and 40. A secondary intermediate transfer body 42 onto which an image is further transferred, and a tertiary transfer roll 44 that further transfers the developer image transferred onto the secondary intermediate transfer body 42 onto a sheet.

  The primary intermediate transfer member 38 has a drum shape and is in contact with the photosensitive member 22C provided in the cyan process cartridge 20C and the photosensitive member 22B provided in the black process cartridge 20B. . The black developer image formed on the photoreceptor 22B and the cyan developer image formed on the photoreceptor 22C are transferred to the primary intermediate transfer member 38, and cyan development is performed on the surface of the primary intermediate transfer member 64. The agent image and the black developer image are superimposed.

  The primary intermediate transfer member 40 has a drum shape and is disposed above the primary intermediate transfer member 38. The primary intermediate transfer member 40 is in contact with the photosensitive member 22Y provided in the yellow process cartridge 20Y and the photosensitive member 22M provided in the magenta process cartridge 20M. The yellow developer image formed on the photoreceptor 22Y and the magenta developer image formed on the photoreceptor 22M are transferred to the primary intermediate transfer body 40, and yellow development is performed on the surface of the primary intermediate transfer body 40. The agent image and the magenta developer image are superimposed.

  The secondary intermediate transfer member 42 has a drum shape and is in contact with the primary intermediate transfer member 38 and the primary intermediate transfer member 40, and a cyan developer image and a black developer on the surface of the primary intermediate transfer member 38. The image is transferred, and the yellow developer image and magenta developer image on the surface of the primary intermediate transfer member 40 are transferred. In this way, developer images of four colors of yellow, magenta, cyan, and black are superimposed on the surface of the secondary intermediate transfer member 42.

  The tertiary transfer roll 44 is in contact with the secondary intermediate transfer body 42, forms a nip portion with the secondary intermediate transfer body 42, and yellow, magenta, cyan, black on the sheet passing through the nip portion. The color developer image on which the four color developer images are superimposed is transferred onto a sheet.

  The fixing device 28 includes a heating roll 28a and a pressure roll 28b. The sheet passing between the heating roll 28a and the pressure roll 28b is heated and pressed to fix the developer image on the sheet.

  The sheet supply device 18 includes a sheet supply cassette 46 that holds the sheets in a stacked state, and a conveyance roll 50 that picks up the sheet from the sheet supply cassette 46 and conveys the sheet toward the sheet conveyance path 48. The sheet conveyance path 48 is a path through which a sheet is conveyed from the sheet supply cassette 46 to the discharge roller 52. The sheet conveyance path 48 includes, in order from the upstream side in the sheet conveyance direction, a conveyance roll 50, a registration roller 54, and a tertiary roller. A nip portion formed by the transfer roll 44 and the secondary intermediate transfer body 42, the fixing device 28, and the discharge roller 52 are disposed.

  Accordingly, each photosensitive member 22 is uniformly charged by the charging device 32, a latent image is formed by the optical writing device 24, and the latent image is visualized by the developer by the developing device 34. The developer image formed on each photoconductor 22 is transferred to the primary intermediate transfer members 38 and 40 and then transferred to the secondary intermediate transfer member 42. On the other hand, the sheets in the sheet supply cassette 46 are conveyed to the sheet conveyance path 48 by the conveyance roll 50, and the developer image is transferred at the nip portion between the secondary intermediate transfer body 22 and the tertiary transfer roll, and developed by the fixing device 28. The agent image is fixed and discharged to the discharge unit 14 by the discharge roller 52.

FIG. 2 shows details of the process cartridge 20.
As described above, the process cartridge 20 has the process cartridge main body 30, and the process cartridge main body 30 is provided with the photosensitive member 22, the charging device 32, the developing device 34, the cleaning device 36, and the like.

  The process cartridge main body 30 is provided with a laser light path 30a extending from one end portion in the horizontal direction to the vicinity of the other end portion, and the laser light from the optical writing device 24 passes through the laser light path 22a to the photosensitive member 22. To reach. An engagement portion 30 b is formed at one end of the process cartridge main body 30. As described above, the process cartridge 20 is detachably provided on the image forming apparatus main body 12 (shown in FIG. 1). When the process cartridge 20 is mounted on the image forming apparatus main body 12, this engagement is performed. The part 30b and the engaged part (not shown) of the image forming apparatus main body 12 are engaged with each other.

  The cleaning device 36 includes a cleaning blade 56 and a waste developer container 58. The cleaning blade 56 scrapes off and removes the developer remaining on the surface of the photosensitive member 22, and the waste developer accommodating portion 58 accommodates the waste developer removed by the cleaning blade 56.

  The developing device 34 includes a developing device main body 60, and a first developing supply chamber 62, a second developing supply chamber 64, and a developing chamber 66 are formed in the developing device main body 60.

  The first development supply chamber 62 is located above the second development supply chamber 64 and stores the developer supplied to the second development supply chamber 64. Between the first development supply chamber 62 and the second development supply chamber 64, a developer transport path 68 that connects the first development supply chamber 62 and the second development supply chamber 64 is provided. Yes. Accordingly, the developer in the first development supply chamber 62 is supplied to the second development supply chamber 64 via the developer conveyance path 68.

  The second development supply chamber 64 is located on the side of the development chamber 66 and stores the developer supplied to the development chamber 66. A second agitating and conveying member 72 is disposed between the second developing supply chamber 64 and the developing chamber 66, and the second agitating and conveying member 72 is connected via a developer passage (not shown). The developer in the second development supply chamber 64 is supplied to the development chamber 66. The second developer supply chamber 64 is provided with two first agitating and conveying members 70 and 70 as rotating members, and these first agitating and conveying members 70 and 70 are provided with a second developing supply. The developer in the chamber 64 is agitated and the developer is conveyed in the direction of the second agitating and conveying member 72.

  The developing chamber 66 is located below the photosensitive member 22, and a developing roll 74, a third agitating / conveying member 76, and a fourth agitating / conveying member 77 as rotating members are disposed in the developing chamber 66. Yes. The third agitating and conveying member 76 and the fourth agitating and conveying member 77 convey the developer in the developing chamber 66 to the developing roll 74, and the developing roll 74 has the third agitating and conveying member 76 and the fourth agitating and conveying. The developer conveyed by the member 77 is supplied to the photoreceptor 22. The third agitation transport member 76 and the fourth agitation transport member 77 have a drive transmission shaft 90 to be described later, and the third agitation transport member 76 and the fourth agitation transport member 76 are driven by the driving force transmitted by the drive transmission shaft 90. No. 4 stirring / conveying member 77 rotates. Further, a trimmer bar 78 as a layer thickness regulating member is arranged in the vicinity of the developing roll 70 and regulates the layer thickness of the developer conveyed by the developing roll 74. The trimmer bar 78 is formed in a cylindrical shape and is made of a nonmagnetic metal material such as aluminum.

Details of the developing device 34 are shown in FIGS.
As shown in FIG. 3, the developing roll 74 includes a developing sleeve 80 and a magnet roll 82. The developing sleeve 80 is made of, for example, a nonmagnetic conductive member such as an aluminum alloy or stainless steel, and is rotatably supported by the developing device main body 60. The magnet roll 82 is disposed in a fixed state inside the developing sleeve 80, and a plurality of magnetic poles are magnetized on the magnet roll 82. For example, an S pole as a main developing pole at a position facing the photoconductor 22, and, for example, two N poles as a developer peeling magnetic pole at a position downstream of the main developing pole in the rotation direction of the developing roll 74 are trimmer bars. The S pole is magnetized at a position facing 78, and the N pole for transporting the developer is magnetized between the S pole and the main development pole.
The magnet roll 82 may be rotatably supported with respect to the developing device main body 60.

  As shown in FIGS. 4 and 5, the developing device main body 60 includes a plurality of bearing portions 84 (bearing portions 84 a, 84 b, 84 c) on which the rotation shafts and fixed shafts of members disposed in the developing device main body 60 are supported. Is formed. The bearing portion 84 a supports a support shaft 86 provided on the magnet roll 82 of the developing roll 74 via the bearing member 88. The bearing portion 84 b supports the drive transmission shaft 90 provided at one end portion of the fourth stirring and conveying member 77 via the bearing member 92, and the bearing portion 84 c supports the vicinity of the end portion of the trimmer bar 78. As the bearing members 88 and 92, for example, a rotary bearing such as a ball bearing or a sliding bearing made of a sliding member such as a sintered metal such as copper impregnated with oil is used. Is preferred.

  As shown in FIGS. 3 to 6, the magnetism generating means 95 includes the magnet roll 82 and the magnetic plate 94 described above. The magnetic plate 94 is made of a magnetic member such as magnetic stainless steel that is magnetized in a magnetic field. The magnetic member 94 is fixed to the developing device main body 60 with, for example, an adhesive, and is disposed in the vicinity of the magnet roll 82 so as to be located in a range where the magnetic force of the magnet roll 82 can reach. Therefore, the magnetic plate 94 is magnetized by the magnetic force of the magnet roll 82. As shown in FIG. 3, the magnetic plate 94 is formed with a notch 94a and a through hole 94b. The notch 94 a is formed in an arc shape having a radius that is slightly larger than the radius of the developing roll 74. Therefore, at least a part of the outer periphery of the developing roll 74 (a part corresponding to a part having a high developer density in the developing chamber 66) and the notch part 94a of the magnetic plate 94 do not come into contact with each other (d1 in FIG. 3). ) And keep close. The through hole 94d is formed in an arc shape having a diameter slightly larger than the outer diameter of the drive transmission shaft 90. Therefore, the through-hole 94d and the outer periphery of the drive transmission shaft 90 are close to each other while maintaining a predetermined distance (d2 in FIG. 3) without contact. The upper end portion 94c of the magnetic plate 94 is close to the trimmer bar 78 while maintaining a predetermined distance (d3 in FIG. 3).

Therefore, a magnetic seal is formed between the notch 94a and the developing sleeve 80, between the through hole 94b and the drive transmission shaft 90, and between the upper end 94c and the trimmer bar 78. In this way, the outer periphery of the plurality of rotating members is sealed by the magnetism generating means 95. As a result, the developer contained in the developing device main body 60 is shielded by the magnetic seal, and the developing device is generated via the engaging portion between the developing device main body 60 and the rotating member, that is, the bearing portions 82a, 84b, 84c. 34 The leakage of the developer to the outside can be prevented.
The magnetism generating means 95 forms a magnetic seal only on the outer periphery of the developing roll 74 corresponding to the portion where the developer density in the developing chamber 66 is high, but the magnetic seal is formed on the entire outer periphery of the developing roll 74. May be formed.

  The magnet 92 (shown in FIG. 5) is fixed to the developing device main body 60 and is disposed in the vicinity of the magnetic plate 94 so as to be located in a range where the magnetic force of the magnet 92 reaches the magnetic plate 94. The magnet 92 is formed in an arc shape having a predetermined thickness with a radius slightly larger than the radius of the developing roll 74. The magnetic plate 94 may be magnetized by the magnetic force of at least one of the magnet roll 82 and the magnet 92.

  As described above, according to the developing device 10 of the present invention, the outer periphery of the developing sleeve 80 of the developing roll 74 and the drive transmission shaft 90 of the fourth stirring / conveying member 77 is sealed by the magnetism generating means 95. Even if the magnetic generating means 95 is not provided in the respective bearing portions of 74 and the fourth agitating / conveying member 77, the leakage of the developer can be prevented, and the number of parts and the cost can be reduced. Further, according to the developing device 10 of the present invention, the developer can be prevented from leaking without using a seal member such as an oil seal, so that the cost can be further reduced.

  In the above embodiment, the description has been given of sealing the outer periphery of the developing sleeve 80 of the developing roll 74 and the fourth agitating / conveying member 77 by the magnetism generating means 95, but the first agitating / conveying member is not limited to this. The outer periphery of another rotating member provided in the image forming apparatus main body 60 such as 70, the second agitating and conveying member 72, and the third agitating and conveying member 77 may be sealed.

  As described above, the present invention can be used for an image forming apparatus that needs to realize cost reduction.

1 is a side view showing an image forming apparatus according to an embodiment of the present invention. 1 is a longitudinal sectional view showing a process cartridge used in an image forming apparatus according to an embodiment of the present invention. 1 is a longitudinal sectional view showing a developing device according to an embodiment of the present invention. FIG. 4 is a cross-sectional view taken along line AA of FIG. 3, showing the developing device according to the embodiment of the present invention. It is a longitudinal cross-sectional view which shows the state which removed the developing roll etc. in the image development apparatus concerning embodiment of this invention. 1 is a perspective view of a developing device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming apparatus main body 34 Developing apparatus 60 Developing apparatus main body 74 Developing roll 77 Fourth stirring and conveying member 82 Magnet roll 94 Magnetic plate 95 Magnetic generating means 96 Magnet

Claims (7)

A developing device main body;
Magnetism generating means provided in the developing device body;
A plurality of rotating members which are rotatably provided in the developing device main body and whose outer periphery is sealed by the magnetism generating means;
A developing device comprising:   The developing device according to claim 1, wherein the magnetism generating unit includes a magnet and a magnetic plate disposed so as to be located in a range where the magnetic force of the magnet reaches.   3. The developing device according to claim 1, wherein the magnetic plate is disposed so as to be close to at least a part of the outer periphery of the plurality of rotating members.   The developing device according to claim 1, wherein at least one of the plurality of rotating members is a developing roll that develops a latent image with a developer in the developing device main body.   The developing device according to claim 4, wherein the developing roll includes a magnet roll having a plurality of magnetic poles, and the magnet includes the magnet roll.   6. The developing device according to claim 1, wherein at least one of the plurality of rotating members is an agitating and conveying member that conveys and agitates the developer in the developing device main body. A photosensitive member on which a latent image is formed, and a developing device that develops the latent image formed on the photosensitive member with a developer;
The developing device includes a developing device main body,
Magnetism generating means provided in the developing device body;
A plurality of rotating members which are rotatably provided in the developing device main body and whose outer periphery is sealed by the magnetism generating means;
An image forming apparatus comprising:

Images