JP5728425B2 - Developing device and image forming apparatus including the same - Google Patents

Description

  The present invention relates to a developing device used for a copying machine, a printer, a facsimile, a composite machine thereof, and an image forming apparatus including the developing device, and more particularly, a developer containing toner and a magnetic carrier is used, and only toner is applied on a developing roller. The present invention relates to a developing device that develops an electrostatic latent image on a photosensitive member, and an image forming apparatus including the developing device.

  Conventionally, a one-component development method and a two-component development method are known as developing devices for developing an electrostatic latent image on a photoconductor as an image carrier. The two-component development method uses a developer composed of a toner and a magnetic carrier, so that the charge amount is stable over a long period and is suitable for extending the life. For example, a two-component developing type developing device stores a developer containing toner and a magnetic carrier, and supplies the developer from a stirring member to a developing roller. The developing roller has a magnet inside thereof, and the developer is carried on the surface of the developing roller as a magnetic brush by the magnet. The developer is conveyed toward the photoconductor side by the rotation of the developing roller. Furthermore, the developing device has a regulating member that regulates the layer thickness of the developer in order to make the amount of developer conveyed toward the photoreceptor side by rotation of the developing roller constant. Then, only the developer toner carried on the developing roller is supplied to the photoconductor, and the electrostatic latent image on the photoconductor is visualized as a toner image.

  When the regulating member regulates the developer layer thickness to form a uniform developer layer on the surface of the developing roller, the toner in the developer is abraded by the regulating member, and dust around the regulating member To float. The floating toner adheres to the downstream surface of the regulating member with respect to the rotation direction of the developing roller and gradually accumulates. The toner deposit is detached from the regulating member, is carried by the rotation of the developing roller, adheres to the photoreceptor, and is finally transferred to the recording medium, resulting in an image defect.

  Therefore, the developing device described in Patent Document 1 turns off the developing bias power source between the photosensitive member and the developing roller to stop the rotation of the photosensitive member in order to scrape off the toner deposit adhered to the regulating member. Further, the developing roller is rotated in the reverse direction with respect to the time of image formation.

JP 2009-258276 A (paragraphs [0042] to [0044], FIG. 5)

  In addition to the development method described in Patent Document 1, there are various two-component development methods. For example, a developer containing toner and a magnetic carrier is carried on the surface as a magnetic brush by an enclosing magnet, and the magnetic roller that conveys the carried magnetic brush, and the photoconductor and the magnetic roller are arranged to face each other, and magnetically A developer roller that carries the toner in the magnetic brush conveyed by the roller on the surface and supplies the carried toner to the photoreceptor, and a developer on the surface of the magnetic roller that is disposed at a predetermined interval with respect to the magnetic roller. And a regulating member that regulates the layer thickness of the developing device.

  In this developing device, when toner is supplied from the developing roller to the photosensitive member to develop the electrostatic latent image on the photosensitive member, the toner remaining on the surface of the developing roller without being used for developing the electrostatic latent image. When it is peeled off from the surface of the developing roller at the portion facing the magnetic roller, it may float around the developing roller. The floated toner falls onto a regulating member that is arranged to face the magnetic roller. When the image formation is repeated, the toner dropped on the regulating member is stacked. At the time of image formation, if the accumulated toner moves to the magnetic roller and is caught in the gap between the magnetic roller and the regulating member, there is a problem that an image defect such as a vertical stripe occurs on the image.

  The present invention has been made to solve the above-described problems. In a developing device that develops an electrostatic latent image on an image carrier by carrying only toner on the developing roller, the periphery of the developing roller is provided. An object of the present invention is to provide a developing device that collects toner floating on the surface and an image forming apparatus including the developing device.

In order to achieve the above object, a developing device according to a first aspect of the present invention includes a developing container that contains toner,
A developing roller that is disposed to face the image carrier by exposing a part of the outer peripheral surface from the opening of the developing container, and that supplies toner to the image carrier while rotating the surface facing the image carrier;
Using a magnetic brush made of a developer that is disposed to face the developing roller, rotates so as to move in the opposite direction to the developing roller at a portion facing the developing roller, and includes a toner carried on the surface and a magnetic carrier. A magnetic roller for forming a toner layer on the developing roller;
A regulating member that regulates the magnetic brush that is disposed on the upstream side of the facing portion with respect to the rotation direction of the magnetic roller and is carried on the surface of the magnetic roller to a predetermined layer thickness;
A floating toner carrying member that is disposed below the facing portion between the regulating member and the facing portion and is held movably in the radial direction of the magnetic roller;
Driving means for rotating the magnetic roller and moving the floating toner carrying member in a radial direction of the magnetic roller;
The driving means rotates the magnetic roller in a direction opposite to that at the time of image formation during non-image formation, and an interval between one end of the floating toner carrying member and the surface of the magnetic roller is greater than a layer thickness of the magnetic brush. A toner recovery mode in which the floating toner carrying member is moved in a direction approaching the magnetic roller until it becomes smaller can be executed.

  According to a second aspect of the present invention, in the developing device, the driving unit reciprocates the floating toner carrying member in a radial direction of the magnetic roller in the toner recovery mode.

  According to a third aspect of the present invention, in the above developing device, the floating toner carrying member has a toner carrying portion that is inclined with the magnetic roller side down.

  According to a fourth aspect of the present invention, in the developing device, the driving unit includes a motor that rotates the magnetic roller, a gear train that includes a first gear that rotates as the magnetic roller rotates, and the gear train. A second gear meshing with the output gear and swingably held in the radial direction of the magnetic roller, and swinging of the second gear in a direction approaching the magnetic roller causes the floating toner carrying member to move in the magnetic direction. An actuating member that moves in a direction approaching the roller, and a spring member that urges the floating toner carrying member in a direction away from the magnetic roller, and the magnetic roller is rotated in a direction opposite to that during image formation. In this case, the second gear and the operating member swing in a direction approaching the magnetic roller.

  A fifth invention is an image forming apparatus provided with the developing device having the above-described configuration.

  According to the first aspect, during the image formation, the toner floating in the developing container falls on the floating toner carrying member, and the floating toner carrying member carries the floating toner. When the toner recovery mode is executed during non-image formation, the driving unit moves the floating toner carrying member in a direction approaching the magnetic roller, and one end of the floating toner carrying member contacts the magnetic brush on the magnetic roller. The toner carried on the floating toner carrying member during image formation comes into contact with the magnetic brush on the magnetic roller by the movement of the floating toner carrying member in the above direction. The magnetic brush scrapes off the toner carried on the floating toner carrying member by the rotation of the magnetic roller in the direction opposite to that at the time of image formation. Furthermore, the scraped toner moves to the upstream side of the regulating member with respect to the rotation direction of the magnetic roller during image formation and is collected by the rotation of the magnetic roller in the reverse direction, thereby suppressing image defects due to floating toner. it can.

1 is a schematic configuration diagram illustrating an image forming apparatus including a developing device according to an embodiment of the present invention. Side surface sectional drawing which shows the image development apparatus concerning embodiment. The top view which shows roughly the structure of the drive means in the printing mode which concerns on embodiment FIG. 3 is a plan view schematically showing a configuration of a driving unit in the toner recovery mode according to the embodiment. Sectional drawing which shows roughly the state of the floating toner holding member in the printing mode which concerns on embodiment Sectional drawing which shows roughly the state of the floating toner holding member in the toner collection mode which concerns on embodiment

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

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention, and the right side is illustrated as the front side of the image forming apparatus. Under the image forming apparatus 100, a paper feed cassette 1 that accommodates stacked paper is disposed. Behind the paper feed cassette 1 is formed a paper transport path 3 that extends upward and reaches the paper discharge unit 2 formed on the upper surface of the apparatus main body. A pickup roller 4, a registration roller pair 5, an image forming unit 6, a fixing unit 7, and a discharge roller pair 8 are arranged in this order along the sheet conveyance path 3 from the upstream side.

  The paper feed cassette 1 is provided with a paper stacking plate 9 that is rotatably supported with respect to the paper feed cassette 1. The paper stacked on the paper stacking plate 9 is sent out toward the paper transport path 3 by the pickup roller 4. The sheet sent to the sheet conveyance path 3 is conveyed to the registration roller pair 5, and the timing is adjusted by the registration roller pair 5 and supplied to the image forming unit 6.

  The image forming unit 6 forms a predetermined toner image on a sheet by an electrophotographic process. The photoconductor 10 is an image carrier that is pivotally supported in a clockwise direction in FIG. 1, and the photoconductor 10. The charging device 11, the developing device 12, the cleaning device 13, the transfer roller 14 disposed so as to face the photoconductor 10 across the paper conveyance path 3, and the light disposed in front of the photoconductor 10. A toner container 16 that includes a scanning device 15 and supplies toner to the developing device 12 is disposed above the developing device 12.

  The charging device 11 is provided with a conductive rubber roller 11 a to which a power source (not shown) is connected. The conductive rubber roller 11 a is disposed so as to contact the photoreceptor 10. When the photoconductor 10 rotates, the conductive rubber roller 11a contacts the surface of the photoconductor 10 and is driven to rotate. At this time, by applying a predetermined voltage to the conductive rubber roller 11a, The surface is charged uniformly.

  Next, an electrostatic latent image based on the input image data is formed on the photosensitive member 10 by the beam light emitted from the optical scanning device 15, and toner is attached to the electrostatic latent image by the developing device 12 and the photosensitive member. A toner image is formed on the surface 10. Then, the paper is supplied from the registration roller pair 5 to the nip portion (transfer position) between the photoconductor 10 and the transfer roller 14 at a predetermined timing, and the toner image on the surface of the photoconductor 10 is transferred onto the paper by the transfer roller 14. The

  The sheet on which the toner image has been transferred is separated from the photoreceptor 10 and conveyed toward the fixing unit 7. The fixing unit 7 is disposed on the downstream side of the image forming unit 6 in the sheet conveyance direction. The sheet on which the toner image is transferred in the image forming unit 6 includes a heating roller 7 a provided in the fixing unit 7, and this The toner image heated and pressed by the pressure roller 7b pressed against the heating roller 7a is fixed on the toner image transferred to the paper.

  The sheet on which the image is formed is discharged to the paper discharge unit 2 by the discharge roller pair 8. On the other hand, the toner remaining on the surface of the photoconductor 10 after the transfer is removed by the cleaning device 13, the photoconductor 10 is charged again by the charging device 11, and image formation is performed in the same manner.

  The configuration of the developing device 12 mounted on the image forming apparatus 100 is shown in FIG. FIG. 2 is a side sectional view of the developing device.

  The developing device 12 includes a developing container 20 in which a two-component developer containing magnetic carrier and toner (hereinafter simply referred to as a developer) is accommodated. The developing container 20 is agitated and transported by a partition wall 20a. It is partitioned into a supply transfer chamber 22. In the agitating / conveying chamber 21 and the supply / conveying chamber 22, the agitating / conveying screw 25a and the supplying / conveying screw 25b for mixing and charging the toner supplied from the toner container 16 (see FIG. 1) with the magnetic carrier are respectively rotated. It is arranged to be possible.

  Then, the developer is agitated by the agitating and conveying screw 25a and the supply and conveying screw 25b while being conveyed in the axial direction (direction perpendicular to the paper surface of FIG. 2), and passes through the developer (not shown) formed at both ends of the partition wall 20a. It circulates between the stirring conveyance chamber 21 and the supply conveyance chamber 22 through the path. That is, a developer circulation path is formed in the developer container 20 by the agitation transport chamber 21, the supply transport chamber 22, and the developer passage.

  The developing container 20 extends obliquely upward to the right in FIG. 2, a magnetic roller 30 is disposed above the supply / conveying screw 25 b in the developing container 20, and a developing roller 31 is disposed obliquely to the upper right of the magnetic roller 30. Opposed. A part of the outer peripheral surface of the developing roller 31 is exposed from the opening 20b of the developing container 20, and faces the photoreceptor 10 (see FIG. 1). The magnetic roller 30 and the developing roller 31 rotate in the counterclockwise direction in FIG.

  The magnetic roller 30 is composed of a non-magnetic rotating sleeve that rotates counterclockwise in FIG. 2 and a fixed magnet body having a plurality of magnetic poles contained in the rotating sleeve. The magnetic roller 30 (rotating sleeve) is rotated in the direction of the arrow in FIG. 2 by a developing motor 81 and a speed reduction mechanism including a gear (not shown), thereby conveying a magnetic brush made of developer containing toner and a magnetic carrier. .

  The developing roller 31 includes a cylindrical developing sleeve that rotates counterclockwise in FIG. 2 and a developing roller side magnetic pole fixed in the developing sleeve. The magnetic roller 30 and the developing roller 31 are opposed to each other. The positions are opposed to each other with a predetermined gap. The developing roller side magnetic pole has a different polarity from the opposing magnetic pole of the fixed magnet body of the magnetic roller 30. Further, the developing roller 31 (developing sleeve) is rotated in the direction of the arrow in FIG.

  Further, the developing container 20 has a spike cutting blade 35 as a regulating member attached along the longitudinal direction of the magnetic roller 30 (perpendicular to the paper surface of FIG. 2), and the spike cutting blade 35 rotates the magnetic roller 30. With respect to the direction (counterclockwise direction in FIG. 2), it is positioned upstream of the facing portion R between the developing roller 31 and the magnetic roller 30. A predetermined amount of gap is formed between the tip of the ear cutting blade 35 and the surface of the magnetic roller 30.

  A DC voltage and an AC voltage are applied to the developing roller 31, and a DC voltage and an AC voltage are applied to the magnetic roller 30. These DC voltage and AC voltage are applied to each sleeve of the developing roller 31 and the magnetic roller 30 from a developing bias power source via a bias control circuit (both not shown).

  As described above, the developer is agitated by the agitating and conveying screw 25a and the supply and conveying screw 25b, and the toner is charged by circulating through the agitating and conveying chamber 21 and the supplying and conveying chamber 22 in the developing container 20, and is supplied by the supplying and conveying screw 25b. The developer is conveyed to the magnetic roller 30. Then, a magnetic brush (not shown) is formed from the developer on the magnetic roller 30, and the magnetic brush on the magnetic roller 30 is regulated to a predetermined layer thickness by the earbrush blade 35, and then the magnetic roller 30 and the developing roller A thin toner layer is formed on the developing roller 31 by a potential difference between the bias applied to the magnetic roller 30 and the bias applied to the developing roller 31 and a magnetic field.

  The toner thin layer formed on the developing roller 31 by the magnetic brush is conveyed to the opposite portion (developing region D) between the photoconductor 10 and the developing roller 31 by the rotation of the developing roller 31. Since a predetermined bias is applied to the developing roller 31, the toner flies due to a potential difference with the photoreceptor 10, and the electrostatic latent image on the photoreceptor 10 is developed.

  The toner remaining without being used for development is conveyed to the facing portion R between the developing roller 31 and the magnetic roller 30 by the rotation of the developing roller 31 and is collected by the magnetic brush on the magnetic roller 30. The magnetic brush is peeled off from the magnetic roller 30 at the same polarity portion of the fixed magnet body of the magnetic roller 30 and then falls into the supply transfer chamber 22. In the facing portion R, the toner that has not been used for development is peeled off from the developing roller 31 by the magnetic brush of the magnetic roller 30, so that the toner that has not been collected on the magnetic roller 30 of the peeled toner is facing. It floats near the part R.

  Therefore, in the present embodiment, the floating toner carrying member 51 is disposed in the vicinity of the facing portion R and below the toner floating space adjacent to the magnetic roller 30. The floating toner carrying member 51 carries the toner dropped from the toner floating space, and the toner carried on the floating toner carrying member 51 is scraped and collected by the magnetic brush on the magnetic roller 30.

  The floating toner carrying member 51 is provided between the spike cutting blade 35 and the facing portion R so as to face the surface of the magnetic roller 30 and extend in the longitudinal direction of the developing container 20 (direction perpendicular to the paper surface of FIG. 2). . The floating toner carrying member 51 is held by an opening-like holding portion 20e formed in the developing container 20, and can move in the radial direction of the magnetic roller 30 (left and right direction in FIG. 2).

  At the time of image formation, the toner floating in the vicinity of the facing portion R falls on the floating toner carrying member 51, and the floating toner is carried on the floating toner carrying member 51. During non-image formation, the toner collection mode is executed, for example, at every predetermined number of printed sheets or when the image forming apparatus 100 is maintained and inspected. In the toner recovery mode, the floating toner carrying member 51 moves in the direction approaching the magnetic roller 30 (left direction in FIG. 2), and the magnetic roller 30 rotates in the reverse direction during image formation.

  Specifically, when the floating toner carrying member 51 moves in a direction approaching the magnetic roller 30, one end of the floating toner carrying member 51 contacts the magnetic brush on the magnetic roller 30. The toner carried on the floating toner carrying member 51 comes into contact with the magnetic brush on the magnetic roller 30 as the floating toner carrying member 51 moves. Since the magnetic roller 30 rotates in the opposite direction to that during image formation, the magnetic brush scrapes off the toner carried on the floating toner carrying member 51 by the reverse rotation of the magnetic roller 30. Further, by the reverse rotation of the magnetic roller 30, the scraped toner passes through the spike cutting blade 35 and is collected in the supply conveyance chamber 22, and image defects due to accumulation of floating toner can be suppressed.

  Driving means for moving the floating toner carrying member 51 and rotating the magnetic roller 30 in the reverse direction at the time of image formation is configured as shown in FIGS. 3 and 4 are plan views of a gear train that constitutes the driving unit. FIG. 3 shows the state of the printing mode, and FIG. 4 shows the state of the toner recovery mode. 5 and 6 are cross-sectional views of the operating mechanism of the floating toner carrying member 51. FIG. 5 shows the state of the printing mode, and FIG. 6 shows the state of the toner recovery mode.

  As shown in FIG. 3, the driving means includes a developing motor 81 (see FIG. 2) that rotates the magnetic roller 30 (see FIG. 2), a first gear 61 that rotates as the magnetic roller 30 rotates, and a first gear. A gear 62 that meshes with the gear 61, further downstream gears 63 and 64 that transmit rotational force, and a second gear 65 that meshes with the gear 64 and is held so as to be swingable. These gears 61 to 65 are spur gears.

  The first gear 61 and the gears 62 to 64 are rotatably provided on a side plate (not shown), and the first gear 61 is provided coaxially with the rotation shaft of the magnetic roller 30 (see FIG. 2). When the magnetic roller 30 rotates, the first gear 61 rotates integrally with the magnetic roller 30, and the rotational force is transmitted to the second gear 65 via the gear trains 61 to 64. A side plate (not shown) is provided to face the outer wall surface of the developing container 20 (the paper surface side in FIG. 2). Further, the first gear 61 and the gears 62 to 64 may be directly disposed on the outer wall surface of the developing container 20.

  The second gear 65 meshes with the gear 64 that is an output gear and is supported by a swing lever 67 so as to be swingable. A rotation support shaft 67a is fixed to the swing lever 67, and the rotation support shaft 67a is rotatably attached to a side plate (not shown). A rotation shaft 65a of the second gear 65 is rotatably supported on the lower end side of the rotation support shaft 67a of the swing lever 67. Accordingly, the swing lever 67 swings in the directions of arrows S1 and S2 (see FIG. 4) about the rotation support shaft 67a, and the second gear 65 swings together with the swing lever 67.

  With this configuration, in the printing mode (during image formation), when the first gear 61 rotates in the arrow T1 direction as the magnetic roller 30 rotates, the second gear 65 moves in the arrow T1 direction via the gear trains 61 to 64. While rotating, the rotational force in the direction of the arrow T1 is received from the gear 64. Since the second gear 65 is supported by the swing lever 67 so as to be swingable in the directions of arrows S1 and S2 (see FIG. 4), when the rotational force in the direction of arrow T1 is applied, the second gear 65 is moved together with the swing lever 67 in the direction of arrow S1. To turn.

  As shown in FIG. 4, in the toner recovery mode, the magnetic roller 30 is driven to rotate in the reverse direction of the printing mode. When the first gear 61 rotates in the arrow T2 direction along with the reverse rotation of the magnetic roller 30, the second gear 65 rotates in the arrow T2 direction via the gear trains 61 to 64, and the rotational force in the arrow T2 direction is geared. Receive from 64. Since the second gear 65 is supported by the swing lever 67 so as to be swingable in the directions of arrows S1 and S2 (see FIG. 4), when the rotational force in the direction of the arrow T2 is applied, the second gear 65 is moved together with the swing lever 67 in the direction of the arrow S2. To turn.

  Next, the operation mechanism of the floating toner carrying member 51 will be described. As shown in FIG. 5, the floating toner carrying member 51 has a trapezoidal shape in cross section, and is exposed to the outside of the developing container 20 at one end 51 a facing the surface of the magnetic roller 30 and on the opposite side of the one end 51 a. The other end portion 51 b facing the member 69, a carrying portion 51 c that carries floating toner in the developing container 20, and a sliding portion 51 d that is held by and slides on the holding portion 20 e of the developing container 20. The carrier 51c is formed with an inclined surface with the magnetic roller 30 side down so that the carried toner can easily move to the magnetic roller 30 side.

  A spring member 71 made of a tension coil spring or the like is hung on the floating toner carrying member 51, and the floating toner carrying member 51 is biased in a direction away from the magnetic roller 30 by the spring member 71. Further, the other end portion 51b of the floating toner carrying member 51 contacts the holding portion 20e of the developing container 20 by the biasing force of the spring member 71. In this state, the one end portion 51a of the floating toner carrying member 51 and the surface of the magnetic roller 30 Is larger than the layer thickness Ha of the magnetic brush formed on the magnetic roller 30.

  The actuating member 69 is provided integrally with the rotation support shaft 67a of the aforementioned swing lever 67 (see FIGS. 3 and 4), and when the swing lever 67 swings, the same as the swing lever 67 via the rotation support shaft 67a. As described above, it swings around the rotation support shaft 67a. The actuating member 69 has an abutting portion 69b at a position relatively far away from the rotation support shaft 67a so that it can swing greatly. The contact portion 69b is opposed to the other end portion 51b of the floating toner carrying member 51 with a gap in the printing mode (state of FIG. 5). The rotation support shaft 67a is provided so as to extend in the longitudinal direction of the developing container 20. Both ends of the rotation support shaft 67a are rotatably supported by a side plate (not shown), and the operation member 69 is a central portion of the rotation support shaft 67a. Alternatively, a pair of actuating members 69 are attached to both end portions of the rotation support shaft 67a. The actuating member 69 and the spring member 71 constitute a driving means.

  In the printing mode (state shown in FIG. 5), the magnetic brush M on the magnetic roller 30 is regulated to a predetermined layer thickness Ha by the spike cutting blade 35, and the magnetic brush M is moved to the developing roller 31 by the rotation of the magnetic roller 30 in the arrow T1 direction. To the opposite portion R (see FIG. 2). A toner layer is formed on the developing roller 31 using the magnetic brush M at the facing portion R, and the toner on the developing roller 31 is supplied to the photoreceptor 10 (see FIG. 1).

  When the magnetic roller 30 rotates in the direction of the arrow T1, the first gear 61 (see FIG. 3) rotates in the direction of the arrow T1, and the second gear 65 (see FIG. 3) moves through the gear trains 61 to 64 to the arrow T1. It rotates in the direction of arrow S1 together with the swing lever 67. As the swing lever 67 rotates, the rotation support shaft 67a rotates in the same direction, and the operation member 69 further rotates in the arrow S1 direction. In this state, the contact portion 69 b of the operating member 69 is not in contact with the other end portion 51 b of the floating toner carrying member 51, and the floating toner carrying member 51 holds the developing container 20 by the biasing force of the spring member 71. The one end portion 51 a of the floating toner carrying member 51 is not in contact with the magnetic brush M because it is in contact with the portion 20 e.

  In the printing mode, the toner floating in the vicinity of the facing portion R falls on the floating toner carrying member 51, and the toner is carried on the floating toner carrying member 51. When the toner recovery mode is executed at a predetermined timing, the magnetic roller 30 is driven to rotate in the reverse direction of the printing mode.

  As shown in FIG. 6, when the magnetic roller 30 rotates in the direction of arrow T2 (the reverse direction of the printing mode), the first gear 61 (see FIG. 4) rotates in the direction of arrow T2, via the gear trains 61 to 64. The second gear 65 (see FIG. 4) rotates in the arrow T2 direction and rotates in the arrow S2 direction together with the swing lever 67. As the swing lever 67 rotates, the rotation support shaft 67a rotates in the same direction, and the operation member 69 further rotates in the arrow S2 direction.

  When the operating member 69 rotates in the direction of the arrow S2, the contact portion 69b of the operating member 69 contacts the other end portion 51b of the floating toner carrying member 51, and further, the floating toner carrying member resists the biasing force of the spring member 71. 51 is moved to the magnetic roller 30 side. One end 51a of the floating toner carrying member 51 approaches the surface of the magnetic roller 30, and the distance Hb between the one end 51a and the surface of the magnetic roller 30 is smaller than the predetermined layer thickness Ha of the magnetic brush M. That is, one end portion 51 a of the floating toner carrying member 51 contacts the magnetic brush M on the magnetic roller 30, and the toner carried on the carrying portion 51 c of the floating toner carrying member 51 is applied to the magnetic brush M on the magnetic roller 30. Abut. Since the magnetic roller 30 is rotating in the direction of the arrow T2, the rotation of the magnetic roller 30 causes the magnetic brush M to scrape off the toner carried on the carrying part 51c. Further, due to the rotation of the magnetic roller 30 in the direction of the arrow T2, the scraped toner passes through the spike cutting blade 35 and is collected in the supply conveyance chamber 22 (see FIG. 2).

  In the toner recovery mode shown in FIG. 4, when the first gear 61 rotates in the arrow T2 direction by the rotational drive of the magnetic roller 30 in the arrow T2 direction, the second gear 65 rotates along with the gear trains 61 to 64. It rotates in the direction of arrow S2. When the second gear 65 rotates about the rotation support shaft 67a in the direction of the arrow S2, the distance between the shafts of both the gears 64 and 65 becomes longer, and when the second gear 65 reaches a predetermined rotation position, the second gear 65 and the gear 64 is disengaged. When the second gear 65 is disengaged from the gear 64, the floating toner carrying member 51 (see FIG. 6), the actuating member 69 (see FIG. 6), and the spring member 71 (see FIG. 6) via the rotation support shaft 67a. With the urging force, the rotary shaft 67a is rotated in the direction of arrow S1 (opposite to S2). When the second gear 65 returns (rotates) in the direction of the arrow S1, the next gear teeth of the second gear 65 and the gear 64 mesh with each other, and the second gear 65 again moves in the direction of the arrow S2 around the rotation support shaft 67a. Rotate.

  When the magnetic roller 30 continues to rotate in the arrow T2 direction, the second gear 65 reciprocates (oscillates) in the arrow S2 direction and the S1 direction within a predetermined range. As the second gear 65 swings, the actuating member 69 swings in the same manner, so that the abutting portion 69b of the actuating member 69 reciprocates at a predetermined cycle, and the floating toner abuts on the abutting portion 69b. The support member 51 reciprocates (vibrates) in the radial direction of the magnetic roller 30. When the floating toner carrying member 51 vibrates, the toner carried at a position far from the one end portion 51a on the carrying portion 51c easily moves toward the one end portion 51a, and the toner on the carrying portion 51c is further increased by the magnetic brush M. It is scraped off. When the second gear 65 is disengaged, the floating toner carrying member 51 moves to a position where the distance Hb between the one end 51a and the surface of the magnetic roller 30 is reached. It is desirable that the contact portion 69 b of the operating member 69 is in contact with the floating toner carrying member 51 when the 65 is returned to the meshing position. In the printing mode, the second gear 65 reciprocates (swings) within a predetermined range rotated in the S1 direction, and the operating member 69 swings in the same manner. However, in the printing mode, the operating member 69 swings. Even if it moves, it is desirable to arrange it at a position where it does not contact the other end 51b of the floating toner carrying member 51.

  In the above-described embodiment, the configuration using the second gear 65 that swings to swing the operating member 69 is shown. However, the present invention is not limited to this, and the eccentricity that rotates in contact with the operating member 69 is used. A cam and a one-way clutch that transmits a rotational force in only one direction to the eccentric cam. In the toner recovery mode, the eccentric cam is rotated by the rotation of the magnetic roller 30 in the T2 direction. The floating toner carrying member 51 reciprocates through the positions shown in FIGS. 5 and 6 via the actuating member 69 according to the contact position, while the magnetic roller 30 rotates in the T1 direction in the printing mode. In this case, the one-way clutch may be configured such that the floating toner carrying member 51 holds the position shown in FIG. 5 without transmitting the rotational force to the eccentric cam. A ratchet mechanism may be provided instead of the one-way clutch. In these cases, the same effects as those of the above embodiment can be obtained.

  In the above embodiment, the floating toner carrying member 51 is operated by the developing motor 81 that rotationally drives the magnetic roller 30 and the developing roller 31. However, the present invention is not limited to this, and the floating toner carrying member 51 is not limited thereto. May be configured to be operated by a motor or solenoid other than the developing motor 81.

  INDUSTRIAL APPLICABILITY The present invention can be used for a developing device used in a copying machine, a printer, a facsimile, a composite machine thereof, and an image forming apparatus including the developing device. In particular, a developing roller using a developer containing toner and a magnetic carrier is used. The present invention can be used in a developing device that develops an electrostatic latent image on a photosensitive member by carrying only toner thereon and an image forming apparatus including the developing device.

10 Photoconductor (image carrier)
DESCRIPTION OF SYMBOLS 12 Developing apparatus 20 Developing container 20b Opening part 20e Holding part 30 Magnetic roller 31 Developing roller 35 Ear cutting blade (regulating member)
51 floating toner carrying member 51a one end 51b other end 51c carrying 51d sliding 61 first gear (gear train, drive means)
62-64 gear (gear train, drive means)
65 Second gear (drive means)
65a Rotating shaft 67 Swing lever (drive means)
67a Rotating spindle 69 Actuating member (driving means)
69b Contact part 71 Spring member (drive means)
81 Development motor (drive means)
100 Image forming apparatus Ha Magnetic brush layer thickness Hb Space between floating toner carrying members M Magnetic brush

Claims (5)

A developer container for containing toner;
A developing roller that is disposed to face the image carrier by exposing a part of the outer peripheral surface from the opening of the developing container, and that supplies toner to the image carrier while rotating the surface facing the image carrier;
A magnet made of a developer that is disposed opposite to the developing roller and rotates so as to move in a direction opposite to the developing roller at a portion facing the developing roller at the time of image formation and includes toner and a magnetic carrier carried on the surface. A magnetic roller that forms a toner layer on the developing roller using a brush;
A regulating member that regulates the magnetic brush that is disposed on the upstream side of the facing portion with respect to the rotation direction of the magnetic roller and is carried on the surface of the magnetic roller to a predetermined layer thickness;
A floating toner carrying member that is disposed below the facing portion between the regulating member and the facing portion and is held movably in the radial direction of the magnetic roller;
Driving means for rotating the magnetic roller and moving the floating toner carrying member in a radial direction of the magnetic roller;
The driving means rotates the magnetic roller in a direction opposite to that at the time of image formation during non-image formation, and an interval between one end of the floating toner carrying member and the surface of the magnetic roller is greater than a layer thickness of the magnetic brush. A developing device capable of executing a toner recovery mode in which the floating toner carrying member is moved in a direction approaching the magnetic roller until it becomes smaller.   The developing device according to claim 1, wherein the driving unit reciprocates the floating toner carrying member in a radial direction of the magnetic roller in the toner recovery mode.   The developing device according to claim 2, wherein the floating toner carrying member has a toner carrying portion inclined with the magnetic roller side facing down.   The driving means includes a motor that rotates the magnetic roller, a gear train that includes a first gear that rotates as the magnetic roller rotates, and an output gear of the gear train that swings in the radial direction of the magnetic roller. A second gear movably held; an actuating member that moves the floating toner carrying member in a direction approaching the magnetic roller by swinging the second gear in a direction approaching the magnetic roller; and the floating toner A spring member that urges the support member in a direction away from the magnetic roller, and the second gear and the operating member are moved to the magnetic roller when the magnetic roller is rotated in a direction opposite to that during image formation. The developing device according to claim 2, wherein the developing device swings in a direction approaching.   An image forming apparatus comprising the developing device according to claim 1.

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