JP5602491B2 - Development device - Google Patents

Description

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

  In conventional developing devices, in order to prevent toner from leaking from the end of the developing sleeve (developer carrier), toner leakage is prevented by covering the image carrier side of the end of the developing sleeve with a sheet-like cover member. (Patent Document 1).

  In addition, there is a configuration in which a recovery roller is provided on the downstream side of the developing sleeve and the development region, and the developer that rises by the magnetic pole is recovered by the recovery roller to prevent toner leakage (Patent Document 2). Further, as a technique for preventing toner scattering to the lower part of the developing device, there is a technique provided with a collecting roller for collecting scattered toner (Patent Document 3). The collection roller is arranged close to the downstream side of the position where the photoconductor and the developing sleeve are in contact with each other. A bias voltage is applied to the collecting roller, and the collecting roller rotates in the opposite direction to the developing sleeve. The toner scattered from the developing area is deposited or adsorbed on the collecting roller below it. The toner accumulated on the collection roller is conveyed by the rotation drive of the collection roller, scraped off by a scraper, and collected in the developing container. In this way, it is possible to prevent the toner scattered from the developing sleeve from leaking outside the developing container.

JP-A-9-319215 JP 2006-84901 JP2000-112237A

  However, if the sheet-like cover member described in Patent Document 1 and the recovery roller described in Patent Documents 2 and 3 are used in combination to further suppress toner leakage from the developing device, the longitudinal direction of the developing sleeve At the end, a gap is formed between the outer periphery of the collection roller and the sheet-like cover member. For this reason, toner accumulates in this gap, and there is a risk that it will fall out of the developing device as a lump of toner.

  Therefore, the present invention suppresses toner accumulation in the gap by filling the gap between the collection roller and the sheet-like cover member at the end in the longitudinal direction of the developer carrying member. It is an object of the present invention to provide a developing device that can be used together to further prevent toner leakage from the developing device.

In order to solve the above problems, a typical configuration of a developing device according to the present invention includes a developer container that contains a developer, a developer carrier that develops a latent image formed on the image carrier with the developer, and A cover member covering the image carrier side of the developer carrier at a longitudinal end portion of the developer carrier, and a position facing the developer carrier on the downstream side of the development region of the developer carrier. And a collecting roller that collects the developer at the guide, and is provided in a gap between the collecting roller and the sheet material along the developer carrying member, and guides the developer to the collecting roller. It has the member.

  According to the present invention, at the end portion in the longitudinal direction of the developer carrying member, the gap between the collection roller and the sheet-like cover member is filled to suppress the accumulation of toner in the gap, and the collection roller and the sheet-like cover member Can be used together to further prevent toner leakage from the developing device.

1 is a configuration diagram of an image forming apparatus using a developing device according to an exemplary embodiment. (A) It is a block diagram of a developer carrier and a magnetic seal. (B) It is sectional drawing of a developing agent carrier and a magnetic seal. It is an arrangement plan of a sheet-like cover member. (A) It is a block diagram of the developing device of this embodiment. It is a perspective view of this developing device of this embodiment. ... Longitudinal view of the seal part of the developer container of the present invention It is a figure explaining the subject of the composition which used together the sheet-like cover member and the collection roller.

  An embodiment of a developing device according to the present invention will be described with reference to the drawings.

<Image forming apparatus>
FIG. 1 is a configuration diagram of an image forming apparatus using a developing device according to the present embodiment. As shown in FIG. 1, the image forming apparatus 100 is a tandem type full color printer in which a plurality of image forming portions PY, PM, PC, and PK of yellow, magenta, cyan, and black are arranged along an intermediate transfer belt 25.

  In the image forming units PY to PK, the photosensitive drums (image carriers) 1Y to 1K charged by the charging devices 2Y to 2K are exposed by the exposure devices 3Y to 3K to form latent images. The formed latent images are developed as toner images of the respective colors using the toners of the respective colors by the devices 4Y to 4K, and are sequentially superimposed on the intermediate transfer belt 25 passing through the primary transfer portions TY to TK by the primary transfer transfer roller 5Y. Transcribed. Transfer residual toner remaining on the photosensitive drums 1Y to 1K after the primary transfer is removed by the cleaning device 6Y.

  On the other hand, the recording material P stored in the recording material cassette 10 is separated and fed by the pickup roller 11 and the separating device 12, and is conveyed to the secondary transfer portion T2 by the registration roller 13. The primarily transferred toner image is secondarily transferred to the recording material P at the secondary transfer portion T2. The recording material P that has been secondarily transferred is heated and pressed by the fixing roller 71 and the pressure roller 72 of the fixing device 7 to fix the toner image.

  The intermediate transfer belt 25 is supported by a tension roller 21, a driving roller 22, and a counter roller 23. Transfer residual toner adhering to the intermediate transfer belt 25 after the secondary transfer is removed by the belt cleaning device 26.

<Developing device>
FIG. 4A is a configuration diagram of the developing device of the present embodiment. Since the developing devices 4Y to 4K have the same configuration, the developing device 4Y will be described below. As shown in FIG. 4A, the developing device 4Y is provided with developing sleeves (developer carrying members) 41 and 43 that are rotatable in order in the rotational direction of the photosensitive drum 1Y. The toner accommodated in the developing container 40 is carried on the developing sleeves 41 and 43, is charged to a negative polarity, and is applied to the photosensitive drum 1Y having a relatively positive polarity to develop the electrostatic latent image. . The developer, in which a part of the toner is consumed by the development, is carried on the developing sleeve 43, rotates, and is collected again in the developing container 40.

<Magnetic seals 51 and 52>
As shown in FIGS. 4A, 2A, and 2B, the end portions of the developing sleeves 41 and 43 and the opposite side of the photosensitive drum 1Y are covered with the developing sleeves 41 and 43. Band-shaped magnetic seals 51 and 52 are arranged. The magnetic seals 51 and 52 fill the gaps between the magnetic seals 51 and 52 and the developing sleeves 41 and 43 by forming magnetic spikes H of developer on the surface.

  That is, due to the magnetic spike H formed on the magnetic seal 51, the developer carrying area A1 in the developing sleeve 41, the developing area A2 facing the photosensitive drum, and the gap G1 between the developing sleeve 41 and the developing sleeve 43 from the end in the longitudinal direction. It is limited to a predetermined area. Due to the magnetic spikes H formed on the magnetic seal 52, the developer carrying area A3 in the developing sleeve 43, the developer developing area A4 in the developing sleeve 43, and the gap G1 are limited to predetermined areas from the end in the longitudinal direction.

  Accordingly, the developer is prevented from moving in the longitudinal direction through the gap between the magnetic seals 51 and 52 and the developing sleeves 41 and 43 and adhering to the end of the developing sleeve 41 or leaking from the developing container 40. .

  As shown in FIG. 2B, the ends of the magnetic seals 51 and 52 on the side close to the gap G2 between the developing sleeves 41 and 43 are formed as magnetic poles having the same polarity as the S3 magnetic pole of the magnet 44 on the downstream side. . A repulsive magnetic field is formed between the end of the magnetic seal 52, which is an example of a downstream regulating member, and the S3 magnetic pole of the magnet 44, and the developer that rotates around the developing sleeve 43 is conveyed to the gap G2 between the developing sleeves 41 and 43. Is being prevented.

  However, even if the magnetic poles of the magnetic seals 51 and 52 are set in this way, the developer leaking from the gap G2 between the developing sleeves 41 and 43 outside the carrying areas A1 and A3 cannot be completely prevented. For this reason, when a large amount of image formation is performed over a long period of time, the developer accumulates at a position directly below the developing areas A2 and A4 of the developing sleeves 41 and 43 on the guide on which the developing device 4Y is mounted. . When the charged developer is attenuated, the deposited developer is separated into a non-magnetic toner and a magnetic carrier, so that the non-magnetic toner particles are scattered around by a slight wind when the developing device 4Y is pulled to the near side.

  Then, the accumulated developer spreads inward in the longitudinal direction, falls on the intermediate transfer belt 25, and stains the image. Further, the toner carried along with the rotation of the photosensitive drum 1Y reaches the cleaning device 6Y shown in FIG. 1, and stains the area outside in the longitudinal direction from the cleaning blade. For this reason. It is damped by a side seal installed outside the cleaning blade, falls, and accumulates on a guide on which the cleaning device 6Y is mounted. In this case as well, the image spreads on the inner side in the longitudinal direction and falls on the intermediate transfer belt 25 to contaminate the image. Further, a part of the toner passes through the cleaning device 6Y and reaches the charging device 2Y, and the shielding plate and grid of the charging device 2Y are soiled, resulting in an increase in maintenance frequency.

  As shown in FIG. 2A, the two-component developer is scattered toward the photosensitive drum 1Y from the gap G2 outside the carrying areas A1 and A3 more than the gap G1. Then, the non-magnetic toner resulting from the leakage of the two-component developer rotates around the photosensitive drum 1 and causes unnecessary toner contamination around the end of the photosensitive drum 1.

<Sheet Cover Member 70>
Therefore, as shown in FIGS. 3 and 4A, in the developing device 4Y, the outer side (image carrier side) of the developing sleeves 41 and 43 on the photosensitive drum 1Y side is a sheet-like cover member 70 which is an example of a cover member. The developer leaking from the gap G2 is confined in the developing device 4Y. After the developer leaking from the gap G <b> 2 is captured by the sheet-like cover member 70, the developer is collected into the developing container 40 using the rotation of the developing sleeve 43.

  As shown in FIG. 4A, the cross-sectional shape of the sheet-like cover member 70 goes in and out along the outer peripheral shape of the pair of developer carriers (41, 43). As shown in FIGS. 3 and 5, the sheet-like cover member 70 is attached with the upper portion 70 c and the lower portion 70 d fixed to the developing container 40. The side portion 70b on the outer side in the longitudinal direction of the sheet-like cover member 70 is brought into close contact with the developing container 40 so that a gap through which the developer leaks out is not formed. The inner edge 70a of the sheet-like cover member 70 is positioned as close as possible within a range that does not contact the developer carrying area A3 diffused to the outside along with the transfer from the developing sleeve 41 to the developing sleeve 43.

  As a result, the developer leaked from the gap G <b> 2 that cannot be suppressed by the magnetic seals 51 and 52 can be collected into the developing container 40 by the sheet-like cover member 70. Accordingly, it is possible to suppress image contamination due to the leaked developer, toner contamination in the developing device, and the like.

<Recovery roller 80>
As shown in FIG. 4A, the collection roller 80 is disposed on the downstream side in the rotation direction of the developing sleeve 43 from the position where the photosensitive drum 1Y and the developing sleeve 43 are in contact with each other. The collection roller 80 is desirably close to the developing sleeve 43 so as not to contact the photoreceptor 1Y and the developing sleeve 43.

  The developer sleeve 43 falls and scatters due to an impact caused by magnetic spikes on the developing sleeve 43 and a centrifugal force acting when the developing sleeve 43 is driven to rotate. The collection roller 80 collects the developer that falls and scatters. Thereby, contamination inside the image forming apparatus due to the fallen and scattered toner can be suppressed.

  In the present embodiment, the collection roller 80 is disposed substantially immediately below the developing sleeve 43, the interval between the collection roller 80 and the developing sleeve 43 is 1.3 mm, and the radius of the collection roller 80 is 3 mm. The collection roller 80 is disposed at a position where the developer falling from the developing sleeve 43 is collected, and the magnetic brush on the developing sleeve 43 and the collection roller 80 do not contact each other, so that the circulation of the developer is hindered. Therefore, scattering due to toner dropping can be prevented.

  Further, a scattering prevention bias voltage is applied to the collection roller 80 to form an electric field shield due to a potential difference from the developing bias. As a result, the reversal toner that is not transferred to the photoreceptor 1Y and floats is attracted onto the collection roller 80, and the scattered toner can be reduced.

  A scraper 81 is in contact with the collection roller 80 on the downstream side in the rotation direction from the developing sleeve 43. As a result, the scattered developer can be efficiently captured on the collecting roller 80 and collected in the developing container 40.

<Guide member>
However, the configuration using both the sheet-like cover member 70 and the collection roller 80 has the following problems. FIG. 7 is a diagram for explaining the problem of the configuration in which the sheet-like cover member 70 and the collection roller 80 are used in combination. As shown in FIG. 7, a gap T is formed between the collecting roller 80 and the sheet-like cover member 70 at the longitudinal end portion of the developing sleeve 43, and the developer is accumulated in the gap T. Of the accumulated developer, the developer having a small charge has a small electrostatic adhesion to the collecting roller 80 and is not collected in the developing container 40. The developer having a small charge and accumulated in the gap T eventually overflows from the end of the developing container 40 and scatters and falls out of the developing container 40.

  Therefore, in the present embodiment, as shown in FIG. 4A, a guide member 82 that fills the gap between the collection roller 80 and the sheet-like cover member 70 is provided. As shown in FIG. 4B, the guide member 82 is arranged at a position that is about 1.0 mm away from the developing sleeve 43 and does not hinder the movement of the developer on the developing sleeve 43. By filling the gap T between the collection roller 80, the developing sleeve 43, and the sheet-like cover member 70 by the guide member 82, accumulation of the developer in the gap T that has turned around the end of the developing sleeve 43 can be suppressed. The guide member 82 is inclined obliquely downward from the sheet-like cover member 70 to the collection roller 80 along the developing sleeve 43, and guides the developer to the collection roller 80.

  The gap amount L between the guide member 82 and the developing sleeve 43 is 0.5 mm or more and 1.2 mm or less. By setting the lower limit of the gap amount L to 0.5 mm, it is possible to suppress the developer on the development three portion 43 from rubbing against the guide member 82 and rapidly deteriorating. Further, by setting the upper limit value 1.2 mm of the gap amount L, it is possible to suppress the leakage of the developer from the gap between the developing sleeve 43 and the guide member 82 due to the internal pressure in the developing container 40.

  The relationship between the gap amount S between the collection roller 80 and the developing sleeve 43 and the gap amount L is set so that S ≧ L. The gap S is set to 1.2 mm or more and 1.7 mm or less. By setting S ≧ L, the toner at the end of the developing sleeve 43 can be collected by the collecting roller 80 without overflowing.

  As shown in FIGS. 4A and 5, the guide member 82 pivotally supports both ends of the collection roller 80. The lower part of the sheet-like cover member 70 is attached to the guide member 82. The lower parts of the guide member 82 and the sheet-like cover member 70 are fixed to the developing container 40 by screws 84a and 84b. By using the guide member 82 as a separate member from the developing container 40, when assembling the collecting roller 80 to the developing container 40, the assemblability when assembling a drive system (not shown) of the collecting roller 80 on the back side of the apparatus is improved. ing. The upper part of the sheet-like cover member 70 is sandwiched between the upper cover member 83 and the developing container 40 and fixed by screws 85.

  FIG. 6 is a configuration diagram of the developing device 4Y. As shown in FIG. 6, a sheet-like cover member 70 and a guide member 82 are disposed at two longitudinal ends of the developing device 4Y, and the guide member 82 pivotally supports the collection roller 80 from both ends. By disposing the guide member 82 only at the end portion in the longitudinal direction and not in the entire longitudinal direction, the collection performance of the scattered toner (reversal toner) by the collection roller 80 also disposed in the entire longitudinal direction is improved. ing.

  With the above configuration, the outer periphery of the collecting roller 80 at the end of the developing sleeve 43 and the gap T between the collecting roller 80 and the sheet-like cover member 70 are filled with the guide member 82, so that toner accumulation in the gap T can be suppressed. As a result, the recovery roller 80 and the sheet-like cover member 70 can be used in combination, and toner leakage from the developing devices 4Y to 4K can be further suppressed. As a result, it is not necessary to prevent image smearing by preventing the toner from dropping to the intermediate transfer portion at the lower part of the developing device, and an apparatus for collecting the leaked toner, and the maintainability is improved.

P ... Recording materials PY to PK ... Image forming portion T ... Gap 100 ... Image forming apparatuses 1Y to 1K ... Photosensitive drum 25 ... Intermediate transfer belt 40 ... Developing containers 41 and 43 ... Developing sleeves 4Y to 4K ... Developing apparatus 7 ... Fixing device 70 ... sheet-like cover member 70a ... edge 70b ... side part 70c ... upper part 70d ... lower part 80 ... collection roller 81 ... scraper 82 ... guide member 83 ... upper cover member

Claims (4)

A developer container containing a developer;
A developer carrier for developing the latent image formed on the image carrier with a developer;
A cover member that covers the image carrier side of the developer carrier at the end in the longitudinal direction of the developer carrier;
A collection roller for collecting the developer at a position facing the developer carrier on the downstream side of the development region of the developer carrier;
In a developing device having
A developing device comprising a guide member that is provided in a gap between the collection roller and the cover member so as to be along the developer carrying member and guides the developer to the collection roller. The developing device according to claim 1, wherein the guide member rotatably supports the collection roller. The developing device according to claim 1, wherein the guide member supports the cover member. 4. The developing device according to claim 1, wherein a gap amount between the collection roller and the developer carrier is larger than a gap amount between the guide member and the developer carrier. 5. .

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