JP2009288576A - Developing unit and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing unit used in a high speed image forming device, which prevents the toner from scattering in a simple configuration, and to provide an image forming device using it. <P>SOLUTION: The developing unit 2 has a developing roller 20 to supply toner to a photoreceptor 11a; a magnetic roller 21 having a magnetic brush of developing agents including magnetic carriers and toner formed on its surface, and supplying toner to the developing roller 20 by making the magnetic brush into contact with the developing roller 20 and applying the bias voltage 56; a developing container 22 having an opening 22a to expose the developing roller 20 to the photoreceptor 11a, develops the electrostatic latent image formed on the photoreceptor 11a, and collects the toner not used when developing. Further, the unit 2 has a gap 62 forming a space in the area collecting the toner from the developing roller 20 to the magnetic roller 21, and a projection 61 to separate the gap 62 from the surface of the developing roller 20. This projection 61 is formed on the developing container 22 closer to the surface of the developing roller 20 than the surface of the magnetic roller 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic system, and an image forming apparatus including the developing device, and in particular, includes a magnetic carrier and a toner. The present invention relates to a developing device that uses a component developer and supplies toner from a magnetic roller to a developing roller, and an image forming apparatus including the developing device.

  In a developing device according to an image forming apparatus using an electrophotographic system, a magnetic roller carrying a two-component developer having a carrier and a toner, and a toner thin layer on the developing roller surface from the developer carried on the surface of the magnetic roller A development system that develops a latent image formed on a photoconductor by forming a gap between the developing roller and the photoconductor and causing the toner to fly from the toner thin layer on the surface of the development roller to the photoconductor However, it has been attracting attention as a device corresponding to high speed and high image quality in a color image forming apparatus.

  In the above developing method, the toner supplied from the magnetic roller to the developing roller jumps to the photosensitive member for development, and the toner remaining on the developing roller is collected without flying from the developing roller to the photosensitive member. Thus, the developing roller is always supplied with fresh toner. To collect the toner remaining on the surface of the developing roller, the toner is returned to the magnetic roller side by scraping the toner from the developing roller with a magnetic brush carried on the magnetic roller.

  However, when the toner is charged more than necessary and overcharged, the toner is charged and aggregated on the surface of the developing roller, the toner is not scraped off from the developing roller by the magnetic brush, and the toner remains attached to the developing roller. If this is the case, the adhered toner is difficult to be developed, and there is a risk of the image density being lowered or an image defect such as a ghost. Further, when the toner becomes insufficiently charged, the toner from the developing roller and the magnetic roller may be scattered and the scattered toner may leak out of the developing device.

  Therefore, in Patent Document 1, a developer composed of magnetic toner and a magnetic carrier, a magnetic roller for forming a magnetic brush of the developer, a developing roller for forming a thin layer of magnetic toner, and an electrostatic latent image are formed. In a developing device that develops an electrostatic latent image by flying magnetic toner onto the photoconductor, magnetic powder is internally added to the magnetic toner particles, and the average particle size of the magnetic powder is predetermined. The developer is improved so that the particle shape of the magnetic powder has a predetermined octahedron.

However, in the above-described prior art, if the two-component developer is composed of a magnetic toner and a magnetic carrier, the manufacturing cost is large, and the image forming apparatus is further increased in speed, the improvement of the developer alone can ensure the developability and the toner. It is difficult to achieve both prevention of scattering.
JP 2006-259533 A (paragraph [0020], FIG. 3)

  The present invention has been made to solve the above-described problems, and includes a developing device that prevents toner scattering with a simple configuration even in a developing system used in a high-speed image forming apparatus. An object is to provide an image forming apparatus.

  In order to achieve the above object, the present invention is provided with a developing roller that is disposed opposite to an image carrier that forms an electrostatic latent image, carries toner on its surface, conveys it, and supplies the toner to the image carrier. A magnetic roller for supplying toner to the developing roller by forming a magnetic brush made of a developer comprising a magnetic carrier and toner on the surface, contacting the magnetic brush with the developing roller and applying a bias voltage; and A developing container that rotatably holds the developing roller and the magnetic roller and that has an opening that exposes the developing roller toward the image carrier, and develops the electrostatic latent image formed on the image carrier; In the developing device that collects toner that is not used for development, a gap portion that forms a space in a portion where toner is collected from the developing roller to the magnetic roller, and the gap portion and the developing roller And a projecting portion for partitioning and La surface, the protrusion is characterized in that it is provided in the developer container to be close to the developing roller surface from the magnetic roller surface.

  According to this configuration, the toner that is not used for development on the surface of the developing roller returns to the magnetic roller side as the developing roller rotates, and comes into contact with the magnetic brush on the surface of the magnetic roller and is scraped off from the surface of the developing roller by the magnetic brush. Collected. When the toner is collected, the toner concentration of the developer rapidly increases at the portion where the toner contacts the magnetic brush. Therefore, charging failure such as insufficient charging of the toner occurs and the toner scatters from the developing roller. An air flow generated by the rotation of the roller and the magnetic roller flows toward the gap, and the scattered toner flows along the air flow and is stored in a space formed in the gap.

  According to a second aspect of the present invention, when the developing roller and the magnetic roller rotate, an air swirl is generated in the gap. According to this configuration, the air flow generated by the rotation of the developing roller and the magnetic roller flows toward the gap, and the air flow circulates in the space formed by the gap and the protrusion provided at a predetermined position. The scattered toner flows along the swirl and is stored in the space.

  The invention described in claim 3 is characterized in that a capturing member for attaching toner to the gap is provided. According to this configuration, the toner circulating in the space formed by the gap portion adheres to the capturing member.

  According to a fourth aspect of the present invention, the magnetic roller is disposed below the developing roller, the gap is disposed on a side of the developing roller, and the capturing member is a conductive member extending downward. It is characterized by being formed with a brush. According to this configuration, when the toner stored in the space formed by the gap portion electrostatically adheres to the conductive brush and the amount of the adhered toner increases, the toner moves downward along the brush extending downward. And is collected on the magnetic roller side.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus equipped with the developing device having the above configuration.

  According to the first aspect of the present invention, the toner that is not used for developing on the surface of the developing roller returns to the magnetic roller side as the developing roller rotates, and comes into contact with the magnetic brush on the surface of the magnetic roller. It is scraped off and collected. When the toner is collected, the toner concentration of the developer rapidly increases at the portion where the toner contacts the magnetic brush. Therefore, charging failure such as insufficient charging of the toner occurs and the toner scatters from the developing roller. The air flow generated by the rotation of the roller and the magnetic roller flows toward the gap, and the scattered toner is stored in the space formed in the gap when the air flows along the air flow. The toner can be prevented from leaking out of the developing device with a simple configuration.

  According to the second aspect of the present invention, the air flow generated by the rotation of the developing roller and the magnetic roller flows toward the gap, and the air flow is formed by the gap and the protrusion provided at a predetermined position. In this space, the circulated vortex flows, and the scattered toner flows in the vortex and is stored in the space. Therefore, the scattered toner can be reliably stored in the space formed in the gap. it can.

  According to the third aspect of the present invention, the toner circulating in the space formed by the gap portion adheres to the capturing member, so that toner scattering can be reliably prevented.

  According to the fourth aspect of the present invention, the toner stored in the space formed by the gap is electrostatically attached to the conductive brush, and the brush extending downward as the amount of the attached toner increases. Accordingly, the toner falls downward and is collected on the magnetic roller side, so that it is possible to prevent the toner from scattering even if the toner is repeatedly developed and the scattered toner increases.

  According to the fifth aspect of the present invention, it is possible to provide an image forming apparatus including a developing device that prevents toner scattering with a simple configuration even if the developing method is used for a high-speed image forming apparatus.

  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.

(First embodiment)
FIG. 1 is a plan view schematically showing an internal configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is a tandem type color printer. As the photosensitive members 11a to 11d as image bearing members that are rotatable, an organic photosensitive member (OPC photosensitive member) is used as a photosensitive material for forming a photosensitive layer. Black (B), yellow (Y), cyan (C), and magenta (M) are arranged corresponding to each color. The photosensitive layer may be amorphous silicon. Around each of the photoreceptors 11a to 11d, developing devices 2a to 2d, an exposure unit 12, chargers 13a to 13d, and static eliminators 14a to 14d are disposed.

  The developing devices 2a to 2d are arranged opposite to the lower right of the photoconductors 11a to 11d and supply toner to the photoconductors 11a to 11d. The chargers 13a to 13d are arranged on the upstream side of the developing device 2a to 2d in the rotation direction of the photosensitive member and opposed to the surfaces of the photosensitive members 11a to 11d, and uniformly charge the surfaces of the photosensitive members 11a to 11d. The static eliminators 14a to 14d are arranged on the downstream side of the photoconductor rotation direction of the developing devices 2a to 2d and to face the surfaces of the photoconductors 11a to 11d, and charge remaining on the surfaces of the photoconductors 11a to 11d after development. Remove static electricity.

  The exposure unit 12 scans and exposes each of the photoconductors 11a to 11d based on image data such as characters and patterns input from a personal computer or the like to an image input unit (not shown). The developing device 2a Is provided downstream of the chargers 13a to 13d in the rotation direction of the photosensitive member. The exposure unit 12 is provided with a laser light source and a polygon mirror, and a reflection mirror and a lens are provided corresponding to each of the photoreceptors 11a to 11d. Laser light emitted from the laser light source is applied to the surfaces of the photoconductors 11a to 11d via a polygon mirror, a reflection mirror, and a lens, and the surfaces of the photoconductors 11a to 11d are electrostatically applied to the surfaces of the photoconductors 11a to 11d. A latent image is formed, and the electrostatic latent image is developed into a toner image by each of the developing devices 2a to 2d.

  The intermediate transfer belt 17 is stretched around the tension roller 6, the driving roller 25, and the driven roller 27. The photoconductors 11 a to 11 d are arranged to face the intermediate transfer belt 17 so as to be adjacent to each other along the transport direction (arrow direction in FIG. 1) below the intermediate transfer belt 17. The primary transfer rollers 26a to 26d are arranged so as to be in contact with the intermediate transfer belt 17 so as to face the photoreceptors 11a to 11d with the intermediate transfer belt 17 interposed therebetween. That is, the primary transfer rollers 26a to 26d are pressed against the photoconductors 11a to 11d via the intermediate transfer belt 17 during transfer to form primary transfer nip portions. Separate. In each primary transfer nip portion, the toner images on the photoconductors 11a to 11d are sequentially transferred to the intermediate transfer belt 17 at a predetermined timing as the intermediate transfer belt 17 rotates. On the surface of the intermediate transfer belt 17, cyan, magenta, Four toner images of yellow and black are superimposed. The belt cleaning 31 cleans the toner remaining on the intermediate transfer belt 17 after the transfer.

  The secondary transfer roller 34 is in pressure contact with the driving roller 25 via the intermediate transfer belt 17 to form a secondary transfer nip portion. The toner image on the surface of the intermediate transfer belt 17 is transferred to the paper P at the secondary transfer nip portion.

  A paper feed cassette 32 that stores paper P is disposed below the image forming apparatus 1, and a stack tray 35 that supplies manually fed paper is disposed to the right of the paper feed cassette 32. On the left side of the paper feed cassette 32, a first transport path 33 for transporting the paper P fed from the paper feed cassette 32 to the secondary transfer nip portion formed by the intermediate transfer belt 17 is disposed. On the left side, a second transport path 36 for transporting the sheet fed from the stack tray 35 to the secondary transfer nip portion is provided. Further, in the upper left part of the image forming apparatus 1, a fixing device 18 that performs a fixing process on the paper P on which the toner image is transferred, and a third transport that transports the paper on which the fixing process has been performed to the paper discharge unit 37. A path 39 is provided.

  The paper feed cassette 32 can be replenished by pulling it out of the apparatus (front side in FIG. 1), and the stored paper P is first fed one by one by the pick-up roller 33b and the separating roller 33a. It is fed out to the conveyance path 33 side.

  The first conveyance path 33 and the second conveyance path 36 are joined before the registration roller 33c, and the timing of the image forming operation and the sheet feeding operation in the secondary transfer roller 34 and the intermediate transfer belt 17 by the registration roller 33c. The sheet P is conveyed to the secondary transfer nip portion. The sheet P conveyed to the secondary transfer nip is transferred with the toner image on the intermediate transfer belt 17 by the secondary transfer roller 34 to which a bias potential (polarity opposite to the toner charging polarity) is applied. It is conveyed to.

  The fixing device 18 includes a fixing belt heated by a heater, a pressure roller disposed in pressure contact with the fixing belt, and the like, and performs fixing processing by heating and pressing the paper P on which the toner image is transferred. Do. The fixed sheet P is reversed in the fourth conveyance path 40 as necessary, and the toner image is transferred to the back surface of the sheet by the secondary transfer roller 34 and the intermediate transfer belt 17 and is fixed again by the fixing device 18. The paper is discharged to the paper discharge unit 37 by the discharge roller 19a.

  FIG. 2 is a cross-sectional plan view showing the configuration of the developing device used in the above-described image forming apparatus 1, and the upper side of FIG. 2 shows the upper side of the image forming apparatus 1. In the following description, the configuration and operation of the developing device 2a corresponding to the photoconductor 11a shown in FIG. 1 will be described. However, the configuration and operation of the developing devices 2b to 2d are the same as those of the developing device 2a. Omitted, and reference numerals a to d indicating developing devices of the respective colors are omitted.

  As shown in FIG. 2, the developing device 2 includes a developing roller 20, a magnetic roller 21, a developing container 22, a stirring member 23, a regulating blade 24, and the like.

  The developing container 22 constitutes the outline of the developing device 2, stores a developer made of a magnetic carrier and toner in a developer container 22 c below the developing container 22, and can rotate the stirring member 23, the magnetic roller 21, and the developing roller 20. keeping. The developing container 22 has an opening 22a that exposes the developing roller 20 toward the photoconductor 11a.

  The developing roller 20 faces the photoconductor 11a and is arranged on the right side of the photoconductor 11a in FIG. 2 with a certain gap, and the magnetic roller 21 faces the developing roller 20 with a certain gap and develops. It is arranged on the lower right side of the roller 20. Further, the magnetic roller 21 forms a toner supply region T for supplying toner to the developing roller 20 at a position close to and facing the developing roller 20. The stirring member 23 includes a first mixer 23 a and a second mixer 23 b, and is disposed substantially below the magnetic roller 21. The second mixer 23b is provided below the magnetic roller 21, and the first mixer 23a is provided adjacent to the right side of the second mixer 23b. The regulating blade 24 is fixedly held on the developing container 22 obliquely to the left of the magnetic roller 21.

  The stirring member 23 is composed of two parts, a first mixer 23a and a second mixer 23b. The first mixer 23a agitates the developer composed of the magnetic carrier and the toner to charge the toner in the developer to a predetermined level. Thus, the toner is held on the magnetic carrier. In addition, holes (not shown) are provided at both ends of the partition wall 22b of the developing container 22 that partitions the first mixer 23a and the second mixer 23b in the longitudinal direction (the depth direction in the drawing of FIG. 2). When rotated, the charged developer is conveyed to the second mixer 23b from one hole provided in the partition wall 22b, and the developer circulates between the first mixer 23a and the second mixer 23b. The second mixer 23 b rotates and the developer is supplied to the magnetic roller 21.

  When the developer is stirred by the stirring member 23, the diffusion preventing film 63 generates developer dust so that the developer smoke does not rise toward the developing roller 20. The upper end thereof is fixedly held by the developing container 22, and the lower end thereof is elastically contacted with the magnetic roller 21 to the extent that the rotation of the magnetic roller 21 is not hindered.

  The regulating blade 24 is disposed on the upstream side in the rotation direction of the magnetic roller 21 in the toner supply region T at a predetermined interval with respect to the surface of the magnetic roller 21 and is formed on the surface of the magnetic roller 21 described later. The magnetic brush is adjusted to a predetermined height.

  The magnetic roller 21 includes a roller shaft 21a, a magnetic pole member M, and a magnetic sleeve 21b. The magnetic roller 21 carries the developer stirred by the stirring member 23, and supplies only the toner from the carried developer to the developing roller 20. In the magnetic pole member M, a plurality of magnets having different polarities formed in a sector shape are alternately arranged, and are fixed to the roller shaft 21a by adhesion or the like. The roller shaft 21a is supported by the developing container 22 in a non-rotatable manner by providing a predetermined gap between the magnetic pole member M and the magnetic sleeve 21b in the magnetic sleeve 21b. The magnetic sleeve 21b is rotated in the same direction as the developing roller 20 (clockwise direction in FIG. 2) by a drive mechanism including a motor and a gear (not shown), and applies a bias voltage 56 in which the AC voltage 56b is superimposed on the DC voltage 56a. Is done. On the surface of the magnetic sleeve 21b, the charged developer is carried by forming a magnetic brush by the magnetic force of the magnetic pole member M, and the magnetic brush is adjusted to a predetermined height by the regulating blade 24.

  Here, when the magnetic sleeve 21b rotates, the magnetic brush is carried and conveyed on the surface of the magnetic sleeve 21b by the magnetic pole member M, and when it contacts the developing roller 20 in the toner supply region T, only the toner of the magnetic brush is transferred to the magnetic sleeve. It is supplied to the developing roller 20 in accordance with the bias voltage 56 applied to 21b. Since the magnetic sleeve 21b rotates in the same direction as the developing roller 20, it is easy to supply only toner to the developing roller 20 by being driven to rotate in the opposite direction to the developing roller 20 in the toner supply region T. Become.

  The developing roller 20 includes a roller shaft 20a and a developing sleeve 20b. The roller shaft 20a is rotatably supported by the developing container 22 by fixing the developing sleeve 20b in the developing sleeve 20b. When the roller shaft 20a is rotated by a drive mechanism including a motor and a gear (not shown), the developing sleeve 20b rotates in the arrow direction (clockwise direction) in FIG. Further, a developing bias voltage 55 obtained by superimposing an AC voltage 55b on a DC voltage 55a is applied to the developing sleeve 20b. Here, when the developing sleeve 20b to which the developing bias voltage 55 is applied rotates in the clockwise direction of FIG. 2, the toner is carried and conveyed on the surface of the developing sleeve 20b, and then flies to the photoreceptor 11a by the developing unit D. The electrostatic latent image on the photoconductor 11a is developed.

  After development, undeveloped toner on the surface of the developing sleeve 20b that has not been used to form a latent image on the photoconductor 11a is conveyed from the developing portion D to the toner supply region T by the clockwise rotation of the developing sleeve 20b, and is thus magnetic sleeve. When it comes into contact with the magnetic brush on the surface of 21b, it is scraped off from the surface of the developing sleeve 20b by the magnetic brush and collected on the magnetic roller 21 side.

  However, when the toner is collected, the toner density of the developer rapidly increases in the portion where the undeveloped toner comes into contact with the magnetic brush formed on the magnetic sleeve 21b, so that charging failure such as insufficient charging of the toner occurs. The undeveloped toner scatters from the surface of the developing sleeve 20b, and the scattered toner may float in the space between the developing sleeve 20b and the developing container 22 and leak out of the developing device 2 from the opening 22a of the developing container 22. is there.

  Therefore, the developing container 22 is provided with a thin plate-like protrusion 61 extending in the longitudinal direction. The protruding portion 61 is fixedly held to the developing container 22 at one end thereof, and is developed along the surface of the developing sleeve 20b on the side of the developing sleeve 20b from which the toner is scraped by the magnetic roller 21 from the developing portion D. The sleeve 20b is disposed so as to be separated from the surface of the sleeve 20b by a predetermined distance A, and the other end is directed to the surface of the magnetic sleeve 21b so as to extend from the surface of the magnetic sleeve 21b to the position of the distance B. It is configured.

  Further, on the right side of the developing sleeve 20b, above the magnetic sleeve 21b, a gap 62 is formed in a space surrounded by the inner wall forming the corner of the developing container 22 and the protrusion 61. The gap 62 collects the toner scattered from the surface of the developing sleeve 20b. That is, when the developing sleeve 20b and the magnetic sleeve 21b rotate, an air flow along the rotation direction is generated on the peripheral surfaces of the developing sleeve 20b and the magnetic sleeve 21b. In the vicinity of the toner supply region T, this air flow flows along the inner wall of the developing container 22 in accordance with the rotation direction of the magnetic sleeve 21b and hits the protrusion 61, and the distance A of the protrusion 61 is shorter than the distance B. The vortex flow S circulates in the space formed by the gap 62 and the protrusion 61. The toner scattered in the vicinity of the toner supply region T is taken in the space along the vortex S and stored.

  In the above-described embodiment, the configuration in which the protruding portion 61 is a separate member from the developing container 22 is shown. However, the present invention is not limited to this, and the protruding portion 61 may be formed integrally with the developing container 22 with resin. Good. Further, the protrusion 61 may be made of a metal foil or a conductive resin film instead of the plate-like resin.

  According to the first embodiment, the developing device 2 is disposed so as to face the photoconductor 11a that forms an electrostatic latent image, and carries the toner carried on the surface, and is supplied to the photoconductor 11a. The roller 20 and a magnetic brush made of a developer made of a magnetic carrier and toner are formed on the surface, and the magnetic brush is brought into contact with the developing roller 20 and a bias voltage 56 is applied to supply a magnetic to the developing roller 20. And a roller 21. The developing device 2 includes a developing container 22 that rotatably holds the developing roller 20 and the magnetic roller 21 and has an opening 22a that exposes the developing roller 20 toward the photoconductor 11a, and is formed on the photoconductor 11a. The electrostatic latent image is developed, and the toner not subjected to development is collected. Further, the developing device 2 includes a gap portion 62 that forms a space in a portion where toner is collected from the developing roller 20 to the magnetic roller 21, and a protrusion 61 that partitions the gap portion 62 and the surface of the developing roller 20. The protrusion 61 is provided in the developing container 22 so as to be closer to the surface of the developing roller 20 than the surface of the magnetic roller 21.

  According to this configuration, the toner that is not used for the development on the surface of the developing roller 20 returns to the magnetic roller 21 side as the developing roller 20 rotates, and comes into contact with the magnetic brush on the surface of the magnetic roller 21 from the surface of the developing roller 20 by the magnetic brush. It is scraped off and collected. When the toner is collected, in the portion where the toner contacts the magnetic brush (toner supply region T), the toner concentration of the developer rapidly increases, and charging failure such as insufficient charging of the toner occurs. The air flow generated by the rotation of the developing roller 20 and the magnetic roller 21 flows toward the gap portion 62. When the scattered toner flows along the air flow, the space formed in the gap portion 62 is scattered. Therefore, the toner can be prevented from leaking out of the developing device 2 with a simple configuration in which the protrusion 61 is provided.

(Second Embodiment)
FIG. 3 is a cross-sectional plan view schematically showing the main part of the developing device according to the second embodiment of the present invention. A capturing member provided at a portion where the eddy current S is generated, which is different from the first embodiment, will be described, and the description of the same portion as the first embodiment will be omitted hereinafter.

  The conductive brush 64 as a capturing member has charging properties and is provided in the longitudinal direction of the inner wall of the developing container 22 that forms the gap 62. The plurality of hair tips forming the conductive brush 64 extend toward the magnetic roller 21, so that the toner stored in the space formed by the gap portion 62 and the projection portion 61 is electrostatically applied to the conductive brush 64. As the amount of toner adhering increases, the toner falls downward along its brush tip extending downward due to its own weight and is collected on the magnetic roller 21 side to prevent toner scattering. be able to.

  In the above embodiment, the conductive brush 64 is provided on the inner wall of the developing container 22. However, the present invention is not limited to this, and the conductive brush 64 is provided on the side of the protrusion 61 where the space is formed. It may be. Further, the capturing member may be made of a metal foil or a conductive resin film instead of the conductive brush 64.

  INDUSTRIAL APPLICABILITY The present invention can be used for a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine using the electrophotographic method, and an image forming apparatus including the developing device. The present invention can be used in a developing device that uses a two-component developer having toner and supplies toner from a magnetic roller to a developing roller and an image forming apparatus including the developing device.

FIG. 1 is a plan view schematically showing an overall configuration of an image forming apparatus according to a first embodiment of the present invention. These are the cross-sectional top views which show schematically the developing apparatus which is 1st Embodiment of this invention. These are the cross-sectional top views which show roughly the principal part of the developing device which is 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2a-2d Developing apparatus 11a-11d Photoconductor 20 Developing roller 20a, 21a Roller shaft 20b Developing sleeve 21 Magnetic roller 21b Magnetic sleeve 22 Developing container 22a Opening 23 Stirring member 24 Regulating blade 61 Protruding part 62 Gap part 63 Diffusion Prevention film 64 conductive brush (capturing member)
M Magnetic pole member S Eddy current

Claims (5)

A developing roller that is disposed opposite to an image carrier that forms an electrostatic latent image, carries a toner on its surface, conveys it, and supplies the toner to the image carrier, and a developer comprising a magnetic carrier and toner on the surface Forming a magnetic brush, bringing the magnetic brush into contact with the developing roller and applying a bias voltage, and supplying the developing roller with toner, and rotatably holding the developing roller and the magnetic roller And a developing container having an opening that exposes the developing roller toward the image carrier, and developing the electrostatic latent image formed on the image carrier and collecting toner that is not used for development. In
A gap that forms a space in a portion where toner is collected from the developing roller to the magnetic roller; and a protrusion that divides the gap from the surface of the developing roller. A developing device provided in the developing container so as to be close to a roller surface.   2. The developing device according to claim 1, wherein when the developing roller and the magnetic roller rotate, an air vortex is generated in the gap.   The developing device according to claim 1, wherein a capturing member that causes toner to adhere to the gap is provided.   The magnetic roller is disposed below the developing roller, the gap is disposed on a side of the developing roller, and the capturing member is formed of a conductive brush extending downward. Item 4. The developing device according to Item 3.   An image forming apparatus on which the developing device according to claim 1 is mounted.

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