JP2008129340A - Developing device, image forming structure and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device in which developer is hardly leaked out from a developing device main body and faulty development is hardly caused, and an image forming structure and an image forming apparatus. <P>SOLUTION: The image forming apparatus 10 has the developing device 34. The developing device 34 has: the developing device main body 50 formed with an aperture part 51; a developing sleeve 70 conveying the developer stored in the developing device main body 50; and a magnet roll 72 provided inside the developing sleeve 70. A projection part 80 separating a path 53 connecting the aperture part 51 to the inside of the developing device main body 50 to a first space 55a on the aperture part 51 side and a second space 55b disposed downstream from the first space 55a in the rotating direction of the developing sleeve 70 is provided on a surface on the developing sleeve 70 side in the developing device main body 50. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  In a developing device including a magnet roll in which a conveying magnetic pole is fixed inside a rotating sleeve, the developing device includes a magnet roll in a portion spaced apart from the housing opening in a housing located on the developer return portion side of the magnet roll. In addition to providing a spacer portion that protrudes toward the magnet roll side, a minute gap is formed between the spacer portion and the magnet roll, and one of the transport magnetic poles is disposed at the portion of the magnet roll that faces the spacer portion. A technique is known in which positions of both end portions of the spacer portion are disposed between the transport magnetic pole and transport poles of opposite polarity located on both sides thereof (Patent Document 1).

Japanese Utility Model Publication No. 8-844

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device, an image forming structure, and an image forming apparatus that can make it difficult for a developer to leak out from a main body of a developing device, and can also prevent development failures. .

  A first feature of the present invention is that a developing device main body in which an opening is formed, a developing sleeve that is provided in the opening and conveys a developer accommodated in the developing device main body, and the developing sleeve A magnet provided on the inside, and a passage connecting the opening and the inside of the developing device main body is provided on a surface of the developing device main body on the developing sleeve side, and a first passage on the opening side. In the developing device, a protrusion is provided to separate the space and the second space on the downstream side in the rotation direction of the developing sleeve of the first space.

  Preferably, at least a part of the protrusion is located in a range where the magnetic force of the strength to which the developer of the magnet is attached.

  Preferably, the protrusion is formed integrally with the developing device main body.

  Preferably, the distance between the protrusion and the developing sleeve is longer on the first space side than on the second space side.

  Preferably, the width of the passage at the position of the opening is larger than the width at the position where the magnetic pole of the magnet is provided in the developer transport direction in the downstream side of the opening. wide.

  Preferably, the apparatus further includes a regulating member that regulates the thickness of the developer conveyed by the developing sleeve, and the regulating member is provided at a position facing the magnetic pole of the magnet.

According to a second aspect of the present invention, an image holding body that holds an image, a developing device that supplies a developer to the image holding body and develops a latent image held by the image holding body, The developing device includes: a developing device main body having an opening formed therein; a developing sleeve that is provided in the opening and that transports the developer contained in the developing device main body; and an inner side of the developing sleeve. A magnet provided;
A passage connecting the opening and the inside of the developing device main body, a first space on the opening side, and the first space on the surface of the developing device main body on the developing sleeve side. The image forming structure is provided with a protruding portion that is separated from the second space on the downstream side in the rotation direction of the developing sleeve.

  According to a third aspect of the present invention, an image holding member that holds an image, a developing device that supplies a developer to the image holding member and develops a latent image held by the image holding member, A transfer device that transfers the developer image developed by the developing device to a transfer medium, and the developing device includes a developing device main body in which an opening is formed, and the developing device main body provided in the opening. A developing sleeve that conveys the developer contained in the developing sleeve, and a magnet provided inside the developing sleeve, and the opening and the developing member are formed on a surface of the developing device body on the developing sleeve side. A protrusion is provided that separates a passage connecting the inside of the apparatus main body into a first space on the opening side and a second space on the downstream side in the rotation direction of the developing sleeve in the first space. It is in the image forming apparatus.

  According to the present invention, it is possible to provide a developing device, an image forming structure, and an image forming apparatus that can make it difficult for the developer to leak out from the developing device main body and can make it difficult for development failures to occur. .

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of 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, an image forming unit 14 described later is mounted in the image forming apparatus main body 12, a discharge unit 16 is provided on the upper portion of the image forming apparatus main body 12, and For example, two-stage sheet feeding devices 18 and 18 are disposed below the image forming apparatus main body 12.

  The image forming unit 14 is of an electrophotographic type and is used as an image holding member. For example, a drum-shaped photosensitive member 28, a charging device 30 for uniformly charging the photosensitive member 28, and a photosensitive member charged by the charging device 30. An optical writing device 32 for writing a latent image on the optical device 28 with light, a developing device 34 for visualizing the latent image held on the photosensitive member 28 formed by the optical writing device 32 with a developer, and a photosensitive material developed by the developing device 34 A transfer device 36 that transfers the developer image held by the body 28 onto a sheet used as a transfer medium, a cleaning device 38 that includes a cleaning blade 37 that cleans the developer remaining on the photoreceptor 28, and a transfer device 36. The image forming apparatus includes a fixing device 40 that fixes the developer image on the transferred paper to the paper. The optical writing device 32 includes, for example, a scanning type laser exposure device, and forms a latent image on the photosensitive member 28 across an image forming structure 46 described later. The optical writing device 32 may use an LED or a surface emitting laser as another embodiment.

  Among the members constituting the image forming unit 14, the photoreceptor 28, the charging device 30, the developing device 34, and the cleaning device 38 are integrated as an image forming structure 46 and can be attached to and detached from the image forming apparatus main body 12. It is like that. Details of the image forming structure 46 will be described later.

  The paper feeding device 18 includes, for example, a paper storage unit 19 including a paper feed cassette, a pickup roll 20 that picks up the uppermost paper stored in the paper storage unit, and a feed roll that transports the paper picked up by the pickup roll 20. 21, and the sheets stored in a stacked state in the sheet storage unit 19 are supplied to the image forming unit 14 described above.

  A registration roll 22 is provided downstream of the feed roll 21 in the paper conveyance direction, and the transfer device 36 and the photosensitive member 28 of the image forming structure 46 are provided on the downstream side of the registration roll 22. Is provided with the above-described fixing device 40.

FIG. 2 shows details of the image forming structure 46 according to the embodiment of the present invention.
As described above, the image forming structure 46 is configured such that the photosensitive member 28, the charging device 30, the developing device 34, and the cleaning device 38 are integrated, and can be attached to and detached from the image forming apparatus main body 12. . As shown in FIG. 2, the image forming structure 46 is provided with a handle portion 39 that extends obliquely upward from the cleaning device 38 and has a tip that curves downward. Accordingly, when the image forming structure 46 is taken out from the image forming apparatus main body 12, the image forming structure 46 can be easily taken out from the image forming apparatus main body 12 by grasping the handle 39 and pulling out the image forming structure 46.

The developing device 34 is a developing device that uses a one-component magnetic toner as a developer. The developing device 34 includes a developing device main body 50. The developing device main body 50 contains a developing chamber 52 and a developer conveyed to the developing chamber 52. Storage chamber 54 is provided. An opening 51 is formed in the developing device main body 50, and the developer accommodated in the developing device main body 50 is conveyed to the outside of the developing device main body 50 through the opening 51. An opening 56 is formed in a wall portion separating the developing chamber 52 and the storage chamber 54, and the developer stored in the storage chamber 54 is conveyed to the developing chamber 52 through the opening 56.

  In the storage chamber 54, a transport mechanism 58 used as a transport means is provided. The transport mechanism 58 includes a shaft 60 that rotates clockwise in FIG. 2 and a transport plate 62 attached to the shaft 60. The transport plate 62 is made of a flexible material such as PET (polyethylene terephthalate), for example, so that the tip can come into contact with the inner wall of the storage chamber 54. The conveyance plate 62 that receives the drive transmission from the shaft 60 rotates with the tip portion in contact with the inner wall of the storage chamber 54, and presses the developer to the left side in FIG. The developer is transported from the storage chamber 54 to the developing chamber 52.

  In the developing chamber 52, a developing roll 64 used as a developer holder is provided. The developing roller 64 approaches or contacts the photosensitive member 28, for example, below the direction of gravity of the photosensitive member 28, and supplies developer to the photosensitive member 28 at a position close to or in contact with the photosensitive member 28, and the latent image held by the photosensitive member 28. Develop the image. The detailed configuration of the developing roll 64 will be described later.

  Further, a blade 66 used as a regulating member is provided in the developing chamber 52 so as to contact the developing roll 64. The blade 66 is attached to an attachment member 68, and for example, an elastic resin such as polyurethane or silicon rubber can be used. For example, the blade 66 contacts the developing roll 64 so that the lower end side is elastically deformed, and regulates the layer thickness of the developer held by the developing roll 64. Instead of bringing the blade 66 into contact with the developing roll 64, the end of the blade 66 may be close to the developing roll 64. In this case, the developer on the surface of the developing roll 64 is restricted by the distance between the blade 66 and the developing roll 64.

  FIG. 3 shows an enlarged configuration around the developing chamber 52 and the developing roll 64 of the developing device 34. The developing roll 64 includes a developing sleeve 70 used as a developer conveying member and a magnet roll 72 used as a magnet. The developing sleeve 70 has a hollow portion and has, for example, a cylindrical shape. The developing sleeve 70 is connected to a driving source 74 such as a motor, and rotates in the counterclockwise direction in FIG. 3 in response to driving transmission from the driving source 74.

  The magnet roll 72 is provided on the inner side (hollow part) of the developing sleeve 70, has a substantially cylindrical shape, and is, for example, a permanent magnet in the vicinity of the peripheral surface, for example, four magnetic poles 76a, 76b, 76c, 76d. Are arranged alternately. The blade 66 described above is provided at a position facing the magnetic pole 76a, and is in contact with or close to the developing sleeve 70 at a position facing the magnetic pole 76a. The magnetic pole 76 c is provided at a position facing the position where the developing sleeve 70 is in contact with or close to the photoconductor 28. The magnetic pole 76d is provided at a position facing the position closest to the inner wall of the developing device main body 50 of the developing sleeve 70. Magnetic force is generated from these magnetic poles, and developer spikes made of developer (one-component magnetic toner) are formed on the surface side of the developing sleeve 70.

  A passage 53 that connects the opening 51 and the inside of the developing device body 50 is provided in the developing device body 50. The width of the passage 53, that is, the distance between the developing sleeve 70 side surface of the developing device main body 50 (the inner surface of the developing device main body 50) and the developing sleeve is not constant but varies depending on the position. In the passage 53, the width d at the position of the opening 51 is wider than the width c at the position where the magnetic pole 76 d located immediately downstream of the opening 51 is provided in the developer transport direction.

  On the surface of the developing device body 50 on the developing sleeve side, for example, a protrusion 80 formed integrally with the developing device body 50 is provided. The protrusion 80 divides the passage 53 into a first space 55a on the opening 51 side and a second space 55b on the downstream side in the rotation direction of the developing sleeve 70 in the first space 55a. In this embodiment, the protruding portion 80 is formed integrally with the developing device main body 50, but the protruding portion 80 may be formed as a separate component from the developing device main body 50 and attached to the developing device main body 50.

The distance between the protrusion 80 and the developing sleeve 70 is wider on the first space 55a side than on the second space 55b side. That is, the interval b between the protrusion 80 and the developing sleeve 70 on the first space 55a side is wider than the interval a between the protrusion 80 and the developing sleeve 70 on the second space 55b side.

4 and 5 illustrate positions where the protrusions 80 are provided in the developing device main body 50. FIG. FIG. 4 shows a state in the developing device main body 50 to which a sufficient amount of developer has been supplied. In the developing device main body 50, a developer head 86 is formed in a range where a magnetic force of a strength sufficient to attach the developer generated by the magnet roll 72 on the surface side of the developing sleeve 70 is applied. The protrusion 80 is disposed in the developing chamber 52 so that at least a part thereof is located in a range where the magnetic force of a strength sufficient to attach the developer of the magnet roll 72 is reached. That is, the protrusion 80 is provided at a position where at least a part of the developer spike 86 formed on the surface of the developing sleeve 70 enters.

  When the amount of the developer in the developing chamber 52 becomes less than the amount necessary for good development, as shown in FIG. Therefore, the protrusion 80 may not enter into the ear 86. When the distance from the leading end of the book standing to the developing sleeve 70 in the state where the developer is insufficient and e is the distance from the protrusion 80 to the developing sleeve, the distance e is longer than the distance f.

  In the image forming apparatus 10 configured as described above, the surface of the photoreceptor 28 is uniformly charged by the charging device 30, and a latent image is written by the optical writing device 32 on the surface of the uniformly charged photoreceptor 28. The latent image written on the surface of the photoconductor 28 is developed by the developing device 34, and the developer image formed on the surface of the photoconductor 28 by the development by the developing device 34 is supplied by the resist roll 22 at a predetermined timing. The developer image transferred to the paper to be transferred by the transfer device 36 and transferred to the paper by the transfer device 36 is fixed on the paper by the fixing device 40 to form an image.

  In developing the latent image held by the photosensitive member 28, the developing sleeve 70 rotates in the counterclockwise direction in FIG. 3 in response to the drive transmission from the driving source 74, and the developing sleeve 70 rotates. The developer is conveyed to the outside of the developing device main body 50 through the opening 51 while the thickness is regulated by the blade 66, and the photosensitive member 28 is transported to the outside of the developing device main body by the developing sleeve 70. This is done by visualizing the latent image to be held. The developer that has been transported out of the developing device main body 50 but has not been used for development is transported again into the developing device main body 50 by the rotation of the developing sleeve 70 while being held in the developing sleeve 70. Returned.

  The thickness of the developer held on the developing sleeve 70 is regulated by the blade 66 as described above, and the blade 66 is provided at a position facing the magnetic pole 76a. For this reason, by providing the magnetic pole 76a, the thickness of the developer is regulated at the position where the peak 86 of the developer becomes the largest.

  For example, the pressure in the developing chamber 52 is caused by the rotation of the developing sleeve 70 at a high speed or the transport of the developer in the storage chamber 54 so that the developer is transported to the developing chamber 52 by the transport mechanism 58. The pressure outside the developing device main body 50 may be higher. If the pressure inside the developing chamber 52 becomes higher than the pressure outside the developing device main body 50, the developer stored in the developing device main body 50 flows out of the developing device main body 50 from the opening 51. Is feared to occur.

  In this regard, in the image forming apparatus 10, the protruding portion 80 is provided so that the tip end portion of the protruding portion 80 is inserted into the head 80 (see FIG. 4). For this reason, due to the ears 86 and the protrusions 80, the developer located on the storage chamber 54 side in the developing device main body 50 more than the ears 86 and the protrusions 80 does not move to the opening 51 side. No developer leaks from 51.

  In addition, as shown in FIG. 5, when the amount of the developer is reduced and the tip of the protrusion 80 is not in a state where it protrudes into the head of the developer, the development starts from the tip of the book stand. Since the distance e to the sleeve 70 is longer than the distance f from the protrusion 80 to the developing sleeve, the developer has passed around the bottom of the ear 86 and has passed through the gap between the ear 86 and the protrusion 80. May leak from the developing device main body 50 through the opening 51, but the amount is small.

  Further, as shown in FIG. 3, the protrusion 80 is spaced from the developing sleeve 70 so that the first space 55a side is wider than the second space 55b side. For this reason, the pressure in the first space 55a is not easily increased, and the developer is less likely to leak from the opening 51.

  As shown in FIG. 3, the passage 53 has a width d at the position of the opening 51 at a position where a magnetic pole 76 d is provided that is positioned immediately downstream of the opening 51 in the developer transport direction. It is wider than the width c. For this reason, the width d can be taken sufficiently, and the developer that has not been used for developing the developer held by the photosensitive member 28 is unlikely to accumulate at the position where the opening 51 of the developing device body 50 is formed.

  FIG. 6 shows a developing device 34 according to a first comparative example. As shown in FIG. 6, in the developing device 34 according to the first comparative example, the gap G between the lower side of the developing sleeve 70 and the developing device main body 50 in the opening 51 is large. The developer is likely to leak out of 50. Further, since a developing chamber for supplying developer to the developing sleeve 70 is not provided below the developing sleeve 70 in the direction of gravity, for example, a sufficient amount of developer may not be supplied to the developing sleeve 70. Due to the shortage of the agent, the latent image held on the photoreceptor 28 may not be developed well. In addition, about the same part as embodiment, the same number is attached | subjected to FIG. 6, and description is abbreviate | omitted.

  FIG. 7 shows a developing device 34 according to a second comparative example. As shown in FIG. 7, in the developing device 34 according to the second comparative example, the gap G is narrower than that of the first comparative example. For this reason, in the developing device 34 according to the second comparative example, the developer is less likely to leak from the developing device main body 50 as compared with the developing device 34 according to the first comparative example. However, in the developing device 34 according to the second comparative example, a developing chamber for supplying the developer to the developing sleeve 70 is not provided, for example, below the developing sleeve 70 in the gravitational direction. If the amount of developer may not be supplied and development may not be successful, problems remain. Further, since the gap G is narrowed, the developer that is not used for development and is returned into the developing device main body 50 by the rotation of the developing sleeve 70 is likely to clog the gap G. In addition, about the same part as embodiment, the same number is attached | subjected to FIG. 7, and description is abbreviate | omitted.

  As described above, the present invention can be applied to a developing device, an image forming structure, and an image forming apparatus that perform image formation by developing a latent image using a developer.

1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention. It is sectional drawing which shows the image forming structure which concerns on embodiment of this invention. FIG. 3 is an enlarged cross-sectional view of a part of the developing device according to the embodiment of the present invention. FIG. 5 is a first explanatory diagram illustrating a position where a prevention member included in the developing device according to the embodiment of the present invention is provided. It is the 2nd explanatory view explaining the position in which the prevention member which the developing device concerning the embodiment of the present invention has is provided. It is sectional drawing which shows the image development apparatus concerning the 1st comparative example. It is sectional drawing which shows the image development apparatus concerning the 2nd comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 28 Photoconductor 36 Transfer apparatus 46 Image forming structure 51 Opening part 52 Developing chamber 53 Passage 54 Accommodating chamber 55a First space 55b Second space 64 Developing roll 66 Blade 70 Developing sleeve 72 Magnet roll 76a, 70b , 70c, 70d Magnetic pole 80 Protrusion 86 Earing 88 Range covered by magnetic force

Claims (8)

A developing device main body having an opening formed therein;
A developing sleeve that conveys the developer provided in the opening and accommodated in the developing device main body;
A magnet provided inside the developing sleeve;
Have
A passage connecting the opening and the inside of the developing device main body is provided on a surface of the developing device main body on the developing sleeve side, a first space on the opening side, and the developing sleeve in the first space. The developing device is provided with a protruding portion that is separated from the second space on the downstream side in the rotation direction.   2. The developing device according to claim 1, wherein at least a part of the protrusion is located in a range where a magnetic force of a strength to which the developer of the magnet is attached.   The developing device according to claim 1, wherein the protrusion is formed integrally with the developing device main body.   4. The developing device according to claim 1, wherein a distance between the protrusion and the developing sleeve is longer on the first space side than on the second space side. 5. The width of the passage at the position of the opening is wider than the width at the position where the magnetic pole of the magnet is provided in the vicinity of the downstream in the developer transport direction with respect to the opening. Any one of the developing devices. A regulating member that regulates the thickness of the developer conveyed by the developing sleeve;
The developing device according to claim 1, wherein the regulating member is provided at a position facing the magnetic pole of the magnet. An image carrier for holding an image;
A developing device for supplying a developer to the image carrier and developing a latent image held by the image carrier;
Have
The developing device includes:
A developing device main body having an opening formed therein;
A developing sleeve that conveys the developer provided in the opening and accommodated in the developing device main body;
A magnet provided inside the developing sleeve;
Have
A passage connecting the opening and the inside of the developing device main body is provided on a surface of the developing device main body on the developing sleeve side, a first space on the opening side, and the developing sleeve in the first space. An image forming structure provided with a protruding portion that is separated from the second space on the downstream side in the rotation direction. An image carrier for holding an image;
A developing device for supplying a developer to the image carrier and developing a latent image held by the image carrier;
A transfer device for transferring the developer image developed by the developing device to a transfer medium;
Have
The developing device includes:
A developing device main body having an opening formed therein;
A developing sleeve that conveys the developer provided in the opening and accommodated in the developing device main body;
A magnet provided inside the developing sleeve;
Have
A passage connecting the opening and the inside of the developing device main body is provided on a surface of the developing device main body on the developing sleeve side, a first space on the opening side, and the developing sleeve in the first space. An image forming apparatus provided with a protruding portion that is separated from the second space on the downstream side in the rotation direction.

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