JP4337759B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a copying machine, a printer, a facsimile machine that reproduces an image using a powder developer, a developing device that is applied to a complex machine that has these functions in combination, and an image forming apparatus that includes this developing device. About.

  Conventionally, in an electrophotographic image forming apparatus that reproduces an image using a powder developer, the powder developer is supplied to the electrostatic latent image formed on the electrostatic latent image carrier. Various techniques have been proposed in order to prevent the powder developer from scattering from the developing device for visualizing the image.

For example, in Patent Document 1, a sheet is provided in the vicinity of a developing sleeve carrying toner as a developer and on the downstream side of a regulating plate that regulates the amount of toner conveyed by the developing sleeve, and this sheet is placed on the developing sleeve. A technique for contacting the developer is disclosed. In Patent Document 2, an insulating sheet is arranged so that the tip contacts the developer on the developing sleeve from the tip of the anti-scattering cover facing the developing sleeve to just before the developing region where the developing sleeve and the photosensitive member face each other. Techniques to do this are disclosed. Further, Patent Document 3 discloses a technique in which a regulating member that regulates the amount of developer conveyed by the developing sleeve is provided with a sealing member that seals between the developing sleeve and the regulating member.
Japanese Utility Model Publication No. 7-32663 Japanese Patent Laid-Open No. 11-174978 JP 2000-284690 A

  However, with these technologies, as the system speed increases year by year, the amount of developer scattered as dust increases, and as a result, the developer aggregates on sheets and members that regulate the outflow of dust, The aggregated developer may fall on the developing sleeve and cause image noise.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a technique for reliably preventing dust from scattering even in a high-speed system region and preventing the developer from agglomerating on a powder smoke outflow prevention sheet or the like. .

In order to achieve this object, the present invention opposes a developer carrying member carrying a powder developer on an endless developer carrying surface, with a predetermined interval facing the developer carrying surface, A regulating portion that regulates the amount of developer conveyed by the developer carrying body and a developer carrier facing the developer carrying body at a predetermined interval on the downstream side of the regulating portion with respect to the moving direction of the developer carrying surface. The developer scattering prevention unit is disposed downstream of the developer scattering prevention unit with respect to the movement direction of the developer carrying surface, and a fixed end at one end is fixed to the developer scattering prevention unit, and a free end at the other end A developing device comprising a dust prevention member having a portion in contact with the developer carrying surface, and preventing the developer from scattering from a gap between the developer carrier and the developer scattering prevention portion by the dust prevention member In
Forming a dust discharge opening in the part of the developer scattering prevention part facing the gap,
The smoke prevention member is formed with an air inlet communicating with the gap,
The dust smoke discharge opening is connected to the dust suction and collection means, and the air sucked from the air inflow port is exhausted from the dust smoke discharge opening via the gap .

  In the developing device and the image forming apparatus, it is preferable that the smoke discharge opening is connected to the gap on the upstream side of the gap with respect to the moving direction of the developer carrying surface.

  Further, it is preferable that a plurality of the smoke discharge openings are formed at predetermined intervals in a direction parallel to the central axis of the developer carrier.

  Furthermore, it is preferable that the dust prevention member is formed with an air inflow port communicating with the gap.

  Furthermore, it is preferable that the air inlet is formed on one end side, the other end side, or both end sides of the dust prevention member with respect to a direction parallel to the central axis of the developer carrier.

  The dust suction and collection means preferably includes a filter for capturing the developer.

  According to the developing device and the image forming apparatus having such a configuration, the dust developer present in the gap between the developer carrier and the developer scattering prevention portion is sucked and collected through the dust discharge opening. It is sucked and collected by the means. Therefore, the developer dust does not accumulate on the dust prevention member. As a result, there is no problem that the lump of dust accumulated on the dust prevention member falls on the developer carrying surface and this deteriorates the image quality.

  Embodiments of a developing device and an image forming apparatus equipped with the developing device according to the present invention will be described below with reference to the accompanying drawings. In the description with reference to the following drawings, terms indicating a specific direction (for example, “up”, “down”, “right”, “left”) are used to describe the specific configuration and arrangement shown in the drawing. ”,“ Clockwise direction ”,“ counterclockwise direction ”and derivatives thereof including those terms), these terms are used to facilitate understanding of the invention, and The technical scope of the present invention should not be limitedly interpreted.

  FIG. 1 shows a schematic configuration of a developing device according to the present invention and an image forming apparatus equipped with the developing device. As can be understood from the drawings, the image forming apparatus described in the embodiment is a full-color printer 10 that creates a full-color image on a sheet. However, the application of the present invention is not limited to a printer, and can be similarly applied to other types of image forming apparatuses such as a copying machine, a facsimile machine, and a multifunction machine.

  The printer 10 includes an image creation unit 12 that creates a full-color developer image using four colors of developer inside a casing 11 constituting the appearance. A sheet supply unit 13 is disposed below the image creation unit 12. On the right side of the image creation unit 12, a sheet conveyance unit 15 that conveys a sheet (not shown) discharged from the sheet supply unit 13 upward along a sheet conveyance path 14 indicated by a dotted line is disposed. In the sheet conveyance path 14, a transfer device (secondary transfer unit) 16 that transfers the developer image created by the image creating unit 12 to the sheet, and fixing that heats the developer transferred to the sheet and fixes it to the sheet. A device 17 is provided. A sheet discharge unit 18 for discharging the sheet on which the developer is fixed is provided on the image creating unit 12.

  The image creating unit 12 has a transfer belt 19. The transfer belt 19 is composed of an endless belt, and is wound around a pair of rollers 20 and 21 disposed on the left and right in the drawing, and is driven in a counterclockwise direction in the drawing based on the driving of a motor (not shown). It is designed to rotate. Under the transfer belt 19, there are four imaging units 22 (22Y) that individually create yellow, magenta, cyan, and black images facing the belt portion that moves from the left roller 20 toward the right roller 21. , 22M, 22C, 22K). In the embodiment, the imaging units 22 (22Y, 22M, 22C, and 22K) corresponding to yellow, magenta, cyan, and black are sequentially arranged from the left side to the right side. Referring to the reference numerals shown only for the configuration of the imaging unit 22 (22Y) arranged on the leftmost side in the drawing, each imaging unit 22 is a cylindrical photosensitive member (electrostatic latent image) facing the transfer belt 19. (Supporting member) 23, a charging device 24 for charging the outer peripheral surface of the photosensitive member 23, and an electrostatic image formed on the outer peripheral surface of the photosensitive member by exposing the charged outer peripheral surface of the photosensitive member by an image exposure device 25 described below A developing device 26 that develops (visualizes) the latent image with a developer, and a collection device 27 that collects the developer remaining on the outer peripheral surface of the photoreceptor after the visualized developer is transferred to the transfer belt 19. Are integrally provided, and are detachable from the printer 10. An exposure device 25 is arranged under each imaging unit 22 so that light corresponding to an image to be reproduced is exposed from the charging device 24 and the developing device 26 to the outer peripheral surface of the photoreceptor. A transfer roller 28 is disposed inside the transfer belt 19 so as to face the photoconductor 23 of each imaging unit 22. On the transfer belt 19, a developer replenishing unit 29 for replenishing developer (toner described later in the embodiment) to the developing device 26 of each imaging unit 22 is disposed. The collection unit 30 is disposed so as to face the roller 20.

  The operation of the printer 10 configured as described above will be described. In the image creating unit 12, the photosensitive member 23 rotates clockwise in a necessary imaging unit 22 based on a print signal output from a print command device (personal computer, network, etc.) (not shown), and the charging device 24 rotates the outer periphery of the photosensitive member. The surface is charged to a predetermined potential. Next, on the outer peripheral surface of the charged photoconductor 23, light corresponding to the image to be reproduced is exposed by the exposure device 25 to form an electrostatic latent image. Subsequently, the electrostatic latent image is visualized by the developer supplied from the developing device 26, and a developer image corresponding to the image to be reproduced is formed. Subsequently, the developer image is transferred to the outer peripheral surface of the transfer belt 19 at a portion facing the transfer roller 28 (primary transfer region). The photosensitive member 23 that has passed through the facing portion of the transfer roller 28 moves to the facing portion with the collecting device 27, where untransferred developer is collected to prepare for the next image formation.

  When forming a color image composed of two or more colors, the developer images transferred from the respective imaging units 22 involved in the image formation to the transfer belt 19 are sequentially superimposed on the transfer belt 19. The sheet supplied from the sheet supply unit 13 is conveyed along the sheet conveyance path 14, and the developer image is transferred from the transfer belt 19 to the sheet at a portion facing the transfer device 16 (secondary transfer region). The Next, the sheet is conveyed to the fixing device 17 where the developer image is heated and fixed on the sheet. Finally, the sheet on which the developer image is fixed is discharged to the sheet discharge unit 18.

  2 is a perspective view of the developing device 26 mounted on each imaging unit 22, and FIGS. 3, 4, and 5 are cross-sectional views taken along lines III-III, IV-IV, and VV of the developing device 26 shown in FIG. . In particular, as shown in FIG. 3, a developing roller 32 is disposed in an opening 31 formed facing the photoreceptor 23 inside the housing 30 of the developing device 26, and a supply screw is provided below the developing roller 32. 33 is arranged. A developer 34 is accommodated in the housing 30. In the embodiment, the developer 34 uses a two-component developer, and includes a non-magnetic toner consumed by the above-described image formation and a magnetic carrier for charging the toner to a predetermined polarity. Accordingly, the toner accommodated in the imaging unit 22 (22Y, 22M, 22C, 22K) has colors of yellow, magenta, cyan, and black, and these toners are supplied to the photoconductor 23 at the time of image creation and statically. After the electrostatic latent image is visualized, it is transferred to a sheet through the transfer belt 19.

  The developing roller 32 includes a developing sleeve 35 that is a cylindrical developer carrier, and a magnet body 36 that is disposed inside the developing sleeve 35. The developing sleeve 35 is drivably coupled to a motor (not shown) so as to rotate in the clockwise direction. The magnet body 36 is fixed so as not to rotate, and a plurality of magnetic poles are arranged in a portion facing the inner surface of the developing sleeve 35. For example, magnetic poles S <b> 1 (conveying poles) and N <b> 1 (developing poles) are arranged on the upstream side and the downstream side of the area (developing area 37) where the developing roller 32 and the photoconductor 23 face each other. Further, magnetic poles S2 (sealing pole) and S3 (catch pole) are arranged on the upstream side and the downstream side of the facing region (supply region 38) between the developing roller 32 and the supply screw 33, respectively. The magnetic pole N2 (regulatory pole) is disposed between the magnetic poles S3 and S1, and the developer return member 39 supported by the housing 30 and the tip of the regulating member 40 are developed so as to face the magnetic pole N2. The sleeve 35 is opposed to the outer peripheral surface (developer carrying surface) of the sleeve 35 at a predetermined interval.

  In the developing device 26 configured as described above, the toner of the developer 34 and the carrier are mixed and stirred based on the mixing and stirring action of the supply screw 33 and the like, and the toner and the carrier are charged to a predetermined polarity by mutual frictional contact. (For example, the toner is a negative electrode and the carrier is a positive electrode). The charged developer 34 is supplied from the supply screw 33 to the outer peripheral surface of the developing sleeve 35 in the supply region 38. The developer 34 supplied to the developing sleeve 35 is held on the outer peripheral surface of the developing sleeve 35 by the magnetic force of the magnet body 36 and is conveyed in the clockwise direction as the developing sleeve 35 rotates. The developer 34 conveyed by the developing sleeve 35 is regulated to a certain amount by the developer return member 39 and the regulating member 40, and then contacts the outer peripheral surface of the photoconductor 23 in the development region 37 to develop the electrostatic latent image. To do. Thereafter, the developer 34 that has passed through the developing region 37 is separated from the outer peripheral surface of the developing sleeve 35 before the supply region 38, and is mixed with the developer 34 being stirred by the supply screw 33.

  Of the developer 34 held on the outer peripheral surface of the developing sleeve 35, the magnetic carrier is stably held on the outer peripheral surface of the developing sleeve 35 by the magnetic force of the magnet body 36. On the other hand, the non-magnetic toner is held on the magnetic carrier by electrostatic force applied between the two by frictional contact with the magnetic carrier. However, not all toners are sufficiently charged. Then, the toner that is not sufficiently charged floats inside the developing device housing 30, and a part of the toner flows out to the outside on the airflow formed on the outer periphery based on the rotation of the developing sleeve 35. is there. In particular, in the embodiment, as shown in FIG. 6, a magnetic pole (regulatory pole) N <b> 2 is arranged to face the regulating member 40, and magnetic lines of force are formed toward the regulating member 40 in the vicinity thereof (FIG. 6). 6 is a line of magnetic force formed in a portion surrounded by a dotted ellipse 40a. The developer held on the outer peripheral surface of the developing sleeve 35 forms developer spikes along the lines of magnetic force, and generates dust by collision with the regulating member 40. Therefore, in the developing device 26, as shown in FIGS. 2 and 3, the downstream end of the gap 41 formed between the housing 30 and the developing sleeve 35 on the downstream side of the regulating member 40 is a dust prevention member. The dust prevention sheet 42 is closed.

  The dust prevention sheet 42 is composed of a thin sheet of synthetic resin or the like, one end of which is affixed and fixed to the housing 30, and the free end of the other end is in light contact with the outer peripheral surface of the developing sleeve 35. ing. Although the material which comprises the dust prevention sheet 42 is not specifically limited, Arbitrary materials, such as urethane and PET, can be used, for example. However, a weak material such as urethane makes contact with the developing sleeve 35 and bends smoothly, but a material that is stronger than urethane such as PET comes into contact with the developing sleeve 35 in a substantially straight state. Therefore, when a urethane sheet is used, a sheet of about 0.2 mm is selected, and when a PET sheet is used, a sheet of about 0.05 mm is selected. The length of the dust prevention sheet 42 (the length protruding from the housing) varies depending on the size of the developing device 26 and the developing sleeve 35, but if it is too short, the developer sleeve 35 can not smoothly transport the developer. If the length is too long, the tip may come into contact with the photosensitive member 23. Therefore, it is necessary to consider the length setting sufficiently. In the embodiment, the protruding length is set to about 4.7 mm. However, the material, thickness, and protruding length of the smoke prevention sheet 42 are not particularly limited, and can be appropriately selected in consideration of the above points.

  As a characteristic point in the present invention, with respect to a direction parallel to the central axis of the developing sleeve 35 (direction indicated by an arrow X in FIG. 2), the vicinity of both end portions of the developing sleeve 35 (preferably, a region where no magnetic pole exists (non-attached) In the vicinity of the magnetic region), the dust prevention sheet 42 does not exist, and the gap 41 inside the dust prevention sheet 42 passes through the air inlets 43 formed on both outer sides of the dust prevention sheet 42. It communicates with a space 44 located outside the dust prevention sheet 42. Further, a housing part (developer scattering prevention part) 30a facing the gap 41 has a dust collection chamber 45 extending in a direction parallel to the developing sleeve 35, and a dust connected to the dust collection chamber 45 and the gap 41. A collection opening (powder smoke suction port) 30b (see FIG. 5) is formed. In the embodiment, the dust collection opening 30 b is formed on the upstream side of the gap 41 (that is, in the vicinity of the regulating member 40) with respect to the moving direction of the developing sleeve 36. However, the position where the powder smoke collection opening 30b is formed is not limited to that position. Further, the dust collection opening 30b is formed at the center in the longitudinal direction of the developing device 26, but the place where the dust collection opening 30b is provided is not limited, and is parallel to the central axis of the developing sleeve 35. A plurality of powder smoke collection openings 30b may be arranged almost throughout the developing sleeve 35 with a predetermined interval. Further, as shown in FIG. 2, the dust collection chamber 45 is connected to the dust collection device 47. The dust collecting device 47 has a dust collecting passage (duct) 48, and the dust collecting passage 48 is connected to a filter 49 and a fan 50 as dust collecting means. The filter 49 is replaceable and can be replaced with a new one as necessary. In the embodiment, one end portion of the dust collection chamber 45 is connected to the dust collection passage 48, but the dust collection passage 48 is connected to the other end portion, the center portion, or a plurality of locations of the dust collection chamber 45. May be.

  According to such a configuration, when the fan 50 is driven, the air in the external space 44 is sucked into the gap 41 through the air inlet 43. Further, the air in the gap 41 is sucked into the dust collection chamber 45 through the dust collection opening 30b. Then, the air in the dust collection chamber 45 is discharged to the outside from the dust collection path 48 through the filter 49. Thus, an air flow is formed from the external space 44 via the air inlet 43, the gap 41, the dust collection opening 30b, the dust collection chamber 45, and the dust collection path 48, and rides on this air flow. The smoke present in the gap 41 and the smoke generated in the vicinity of the regulating member 40 are captured by the filter 49 and collected. Therefore, the toner dust does not adhere to and accumulate on the back surface of the developer scattering prevention portion 30a, the regulating member 40 (the surface located downstream with respect to the developing sleeve movement direction) or the dust prevention sheet 42. The accumulated toner does not fall as a lump onto the developing sleeve 35 and adversely affect the image quality. Note that the front surface of the regulating member 40 does not have a problem of toner adhesion due to the developer spikes standing along the lines of magnetic force contacting as described above.

  In addition, the dust discharge opening 43 formed on both outer sides of the dust prevention sheet 42 can be formed by cutting or processing (for example, bending) a part of the dust prevention sheet 42, The smoke prevention sheet 42 may be provided by forming a gap between the smoke prevention sheet 42 and another sheet having different elasticity and thickness based on the difference in elastic deformation between them.

  Further, in an image forming apparatus incorporating a plurality of developing devices, a plurality of developing devices may share one dust collecting device 47, or a plurality of developing devices may be provided with a dust collecting device, respectively.

  Furthermore, in the above description, the dust collection chamber 45 is formed in a part of the housing 30, and the toner dust is sucked from the dust collection opening 30b through the dust collection chamber 45. However, the powder collection opening 30b The route for guiding the dust smoke sucked and discharged from the filter 49 to the filter 49 is not limited to the above-described configuration.

  In the above description, the developer used in the developing device and the image forming apparatus is a two-component developer. However, the present invention can also be applied to a developing device and an image forming apparatus using a so-called one-component developer. is there.

1 is a cross-sectional view of a printer that is an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a perspective view of a developing device built in the printer shown in FIG. 1. FIG. 3 is a cross-sectional view of the developing device shown in FIG. 2 taken along line III-III. FIG. 4 is a sectional view taken along line IV-IV of the developing device shown in FIG. 2. FIG. 4 is a cross-sectional view of the developing device shown in FIG. The graph which shows the magnetic force distribution in the vicinity of a control member, and the state of a line of magnetic force.

Explanation of symbols

10: printer (image forming apparatus), 11: housing, 12: image creation unit, 13: sheet supply unit, 14: sheet conveyance path, 15: sheet conveyance unit, 16: transfer device, 17: fixing device, 18: Sheet discharge unit, 19: transfer belt, 20, 21: roller, 22: imaging unit, 23: photosensitive member (electrostatic latent image carrier), 24: charging device, 25: exposure device, 26: developing device, 27: Collection device, 28: transfer roller, 29: developer replenishment section, 30: housing, 30a: developer scattering prevention section, 30b: dust collection opening, 31: opening, 32: development roller, 33: supply screw, 34: Developer, 35: Development sleeve, 36: Magnet body, 37: Development region, 38: Supply region, 40: Restriction member, 41: Gap, 42: Smoke prevention sheet, 43: Smoke discharge opening, 44 : External space, 5: Smoke recovery chamber, 46: Smoke recovery opening, 47: Smoke recovery device, 48: Smoke recovery path, 49: Filter, 50: Fan, 51: Smoke prevention sheet, 52: Lifting part (deformation) Part).

Claims (7)

A developer carrying member carrying a powder developer on an endless developer carrying surface and a developer carrier which is opposed to the developer carrying surface with a predetermined interval and conveyed by the developer carrying member. A regulating portion for regulating the amount, a developer scattering preventing portion facing the developer carrying member at a predetermined interval on the downstream side of the regulating portion with respect to the moving direction of the developer carrying surface, and the developer carrying surface The powder is disposed downstream of the developer scatter preventing portion with respect to the moving direction of the developer, the fixed end at one end is fixed to the developer scatter preventing portion, and the free end at the other end is in contact with the developer carrying surface. In a developing device that includes a smoke prevention member and prevents the developer from scattering from a gap between the developer carrier and the developer scattering prevention unit by the dust prevention member.
Forming a dust discharge opening in the part of the developer scattering prevention part facing the gap,
The smoke prevention member is formed with an air inlet communicating with the gap,
The development characterized in that the dust smoke discharge opening is connected to the dust suction and collection means, and the air sucked from the air inlet is exhausted from the dust smoke discharge opening via the gap. apparatus. 2. The developing device according to claim 1, wherein the dust smoke discharge opening is connected to the gap on the upstream side of the gap with respect to the moving direction of the developer carrying surface. 3. The development according to claim 1, wherein a plurality of the dust discharge openings are formed at predetermined intervals in a direction parallel to the central axis of the developer carrier. apparatus. The developing device according to claim 1, wherein the dust prevention member has an air inlet communicating with the gap. The said air inflow port is formed in the one end side, the other end side, or both end side of the said smoke prevention member regarding the direction parallel to the center axis | shaft of the said developer carrier. Development device. The developing device according to claim 1, wherein the dust suction and collection unit includes a filter that captures the developer. An image forming apparatus comprising the developing device according to claim 1.

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