Developing device

Abstract

A developing device includes: a developing roller that holds a developer and rotates; an image holding body that is disposed so as to face the developing roller and that rotates; and a developer discharge duct that sucks the developer from the image holding body side and discharges the developer toward another place, the developer discharge duct having: a duct front wall that is disposed on the image holding body side and has a suction port that sucks the developer formed at both end portions in an intersecting direction that intersects a direction in which the developing roller rotates and moves, and a duct rear wall that is disposed on the image holding body side and has a suction port that sucks the developer formed at both end portions in the intersecting direction; a duct rear wall located on a side of the duct front wall opposite to the image holding body; and two duct side walls located at end portions on both sides in the intersecting direction, one of the two duct side walls being provided with a discharge port for discharging the developer at a position adjacent to the duct rear wall, and one of the two duct side walls being provided with a side air suction port for sucking air.

Description

Technical Field

[0001] This invention relates to a developing apparatus. Background Technology

[0002] An image forming apparatus for an electrophotographic system includes a developing apparatus comprising an image holder and a developing agent supplying apparatus for supplying developing agent to the image holder. The developing apparatus includes a developing roller holding developing agent on its surface. The developing agent held on the developing roller is transferred to the image holder, thereby developing an electrostatic latent image on the image holder. A portion of the developing agent not used in development floats near the developing roller and the image holder. Techniques for recovering this floating developing agent are described in Patent Documents 1 and 2 below.

[0003] Patent Document 2 below discloses a technique for discharging developer that has accumulated in a flow path for recovering floating developer. In this document, when no image is being formed, air is introduced into the flow path from an inlet different from the one used when forming an image to generate a strong airflow. The developer that has accumulated through this airflow is then discharged from the flow path.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2003-177604

[0005] Patent Document 2: Japanese Patent Application Publication No. 2013-125148

[0006] If the developer accumulates along with the airflow in the developer recovery path, the path narrows, and blockages may occur depending on the situation. In recent years, there has been a expectation for higher speeds in image forming apparatuses; along with this increase in speed, the amount of developer recovered increases, raising the likelihood of flow path blockages. Summary of the Invention

[0007] The purpose of this invention is to suppress the accumulation of developer in the developer recovery flow path.

[0008] The invention involved in Scheme 1 is a developing apparatus, comprising: a developing roller for holding and rotating developer; an image holder configured to face the developing roller and rotate; and a developer discharge conduit for drawing developer from the image holder side and discharging it elsewhere, the developer discharge conduit having: a front wall disposed on the image holder side, with suction ports for drawing developer formed at both ends in an intersecting direction that intersects the rotational movement direction of the developing roller; a rear wall located on the side of the front wall opposite to the image holder; and two side walls located at both ends in the intersecting direction, with a developer discharge port formed on one of the two side walls adjacent to the rear wall, and a side air intake port for drawing air formed on the other side wall.

[0009] The invention involved in Scheme 2 is the developing apparatus described in Scheme 1, wherein the outlet and the side air intake are formed on the downstream side pipe wall located downstream of the conveying direction of the developer recovery conveying path in the two pipe side walls, and the developer recovery conveying path recovers the developer that is not developed to the image holder from the developing roller and conveys it along the cross direction.

[0010] The invention involved in Scheme 3 is the developing apparatus described in Scheme 2, wherein the developer discharge pipe has a partition wall that extends from the outlet of the downstream pipe sidewall and the side air inlet toward the opposite pipe sidewall, but does not reach the opposite pipe sidewall.

[0011] The invention involved in Scheme 4 is the developing apparatus described in Scheme 3, wherein the edge of the front end of the partition wall is located upstream of the conveying direction of the recoverable developer conveying path in the intersecting direction, compared to the suction port located on the downstream side pipe sidewall.

[0012] The invention involved in Scheme 5 is the developing apparatus described in Scheme 2, wherein an air guiding path is predetermined in the developer discharge pipe, the air guiding path temporarily guiding the air drawn from the side air intake towards the upstream side in the conveying direction of the developer recovery conveying path, and then guiding it towards the discharge outlet.

[0013] The invention involved in Scheme 6 is the developing apparatus described in Scheme 5, wherein the air guiding path temporarily guides the air drawn from the suction port located on the side wall of the downstream pipe, i.e., the downstream suction port, towards the upstream side in the conveying direction of the recovered developer conveying path, and then guides it towards the discharge port.

[0014] The invention involved in Scheme 7 is an image forming apparatus comprising: a developing apparatus as described in any one of Schemes 1 to 6; a charger for charging the surface of the image holder; an exposure apparatus for exposing the charged image holder to light to form an electrostatic latent image on the image holder; a transfer unit for directly or indirectly transferring a developing image obtained by developing the electrostatic latent image using a developing agent supplied from the developing roller onto paper; a fixing unit for fixing the developing image transferred onto the paper onto the paper; and a conveying device for conveying the paper through the transfer unit and the fixing unit.

[0015] Invention Effects

[0016] According to the first aspect of the present invention, the accumulation of developer in the developer recovery flow path can be suppressed compared to the case where no side air intake is formed on the side wall of the pipe.

[0017] According to the second aspect of the present invention, the accumulation of developer near the downstream sidewall of the pipe can be suppressed.

[0018] According to the third aspect of the present invention, compared with the case where the developer discharge pipe does not have a partition wall, the amount of air drawn from the suction port on the upstream side in the conveying direction of the developer recovery conveying path is increased.

[0019] According to the fourth aspect of the invention, compared with the case where the partition wall does not extend beyond the suction port on the downstream side, the degree of imbalance in the amount of air drawn from the two suction ports is reduced.

[0020] According to the fifth aspect of the invention, compared to the case where the air drawn from the side air intake is not predetermined to be temporarily guided towards the upstream side and then guided towards the downstream side, the amount of air drawn from the upstream air intake in the transport direction of the developer transport path is increased.

[0021] According to the sixth aspect of the invention, compared to the case where the air drawn from the downstream suction port is not predetermined to be temporarily guided towards the upstream side and then guided towards the downstream side, the degree of imbalance in the amount of air drawn from the two suction ports is reduced.

[0022] According to the seventh aspect of the present invention, compared with the case where the developing apparatus described in any of the aspects 1 to 6 is not provided, the chance of the image forming apparatus stopping is reduced. Attached Figure Description

[0023] The embodiments of the present invention will be described in detail with reference to the following figures.

[0024] Figure 1 This is a perspective view showing the appearance of the developer supply device of the developing apparatus of this embodiment;

[0025] Figure 2 The developing apparatus of this embodiment is along Figure 1 The sectional view shown is cut along line AA.

[0026] Figure 3 This is a schematic diagram showing the structure of the developer discharge pipe;

[0027] Figure 4 This is an external view showing the side air intake and its surroundings of the developer supply device;

[0028] Figure 5 It is a diagram showing the general structure of an image forming apparatus.

[0029] Symbol Explanation

[0030] 10-Developing device, 12-Image holder, 13-Developer supply device, 14-Developing roller, 16-Sealing sheet, 18-Developer transport path, 20-Developer supply transport path, 22-Developer recovery transport path, 24-Intermediate developer transport path, 32-Developer discharge device, 34-Developer discharge pipe, 38-Lower cover, 40-Lower side section, 42-Pipe bottom plate, 44-Pipe front wall, 46-Pipe rear wall, 48-Pipe side wall, 48U-Upstream side pipe side wall, 48D-Downstream side pipe side wall, 50-Suction port, 50U-Upstream side suction port, 50D-Downstream side suction port, 52-Discharge port, 54-Side suction port, 56-Separator wall. Detailed Implementation

[0031] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 and Figure 2 This is a schematic diagram showing the development apparatus 10 of an image forming apparatus in an electrophotographic system. The development apparatus 10 includes an image holder 12 and a developer supply device 13 for supplying developer to the image holder 12. Figure 1 This is a diagram showing the appearance of the developer supply device 13. Figure 2 It is along Figure 1 The AA-line cross-sectional view shown also shows a portion of the image holder 12 in addition to the developer supply device 13. Figure 1 and Figure 2 The vertical direction corresponds to the direction of gravity when the developing device 10 is placed in the image forming device.

[0032] The developing apparatus 10 is arranged within the image forming apparatus with the image holder 12 and the developer supply device 13 facing each other. An electrostatic latent image is formed on the surface of the image holder 12, and is developed using developer supplied from the developer supply device 13. The developed image formed on the surface of the image holder 12 is transferred to a recording medium such as paper or an intermediate transfer medium. The developed image transferred to the intermediate transfer medium is then transferred to the recording medium. The developer can be a toner. The image holder 12 is, for example, a cylindrical photosensitive roller that rotates about the center line of the cylinder. Figure 2 In the diagram, the direction of rotation of the image holder 12 is indicated by arrow R. Through this rotation, a developer image is sequentially formed at a position on the image holder 12 opposite to the developer supply device 13, and the developer image is transferred to a position on the recording medium.

[0033] The developer supply device 13 includes a developing roller 14 that holds the developer supplied to the image holder 12. The developing roller 14 is configured to face the image holder 12. The developing roller 14 is cylindrical, and its centerline is arranged along the extension direction of the centerline of the cylindrical image holder 12. Furthermore, the developing roller 14 is arranged close to the image holder 12, forming a gap between them. Hereinafter, the area where the developing roller 14 and the image holder 12 are clamped is referred to as the "engaging portion". The developing roller 14 rotates about its centerline. This rotation direction is the direction in which the movement direction of the respective surfaces of the developing roller 14 and the image holder 12 is the same in the portion facing the image holder 12. The rotation directions of the image holder 12 and the developing roller 14 may be opposite to each other. In the portion where the developing roller 14 faces the image holder 12, the direction of surface movement accompanying their rotation is referred to as the "rotational movement direction", and the direction intersecting it is referred to as the "intersecting direction". The intersecting direction is also the extension direction of the centerline of the developing roller 14.

[0034] The developing roller 14 magnetically attracts and retains the developer on its surface. As the developing roller 14 rotates, the developer is supplied to the engagement portion, thereby developing the electrostatic latent image on the image holder 12. In the intersecting direction, sealing plates 16 are disposed at both ends of the engagement portion (see reference). Figure 1 The sealing sheet 16 prevents developer floating in the interlocking area and its surrounding area from flowing out of the area in the cross direction.

[0035] The developer supply device 13 has a developer transport path 18 that supplies developer to and recovers developer from the developing roller 14. The developer transport path 18 includes three straight developer transport paths 20, 22, and 24. However, the number of developer transport paths 18 is not limited to three. The three straight developer transport paths 20, 22, and 24 extend in intersecting directions and transport the developer along these directions while agitating it. Through agitation, the developer becomes charged. The developer transport path 18 also includes a transfer transport path (not shown) that moves the developer between the straight developer transport paths 20, 22, and 24. The developer transport path 20 is the transport path for supplying developer to the developing roller 14; hereinafter, it is referred to as the developer supply transport path 20. In the developer supply transport path 20, the developer is transported along the intersecting directions and supplied to the developing roller 14. Developer transport path 22 is the transport path for developer recovered from developer roller 14, hereinafter referred to as developer recovery transport path 22. Developer transport path 24 is the transport path for delivering developer transferred from developer recovery transport path 22 to developer supply transport path 20, hereinafter referred to as intermediate developer transport path 24.

[0036] A first conveying screw 26 with helical blades is disposed within the developer supply conveying path 20. The first conveying screw 26 is configured such that its axis of rotation is along the extending direction of the developer supply conveying path 20. When the first conveying screw 26 rotates, its helical blades convey the developer along the extending direction of the conveying path, during which the developer is fed toward the developing roller 14 over its entire length. A second conveying screw 28 with helical blades is disposed within the developer recovery conveying path 22. The second conveying screw 28 is configured such that its axis of rotation is along the extending direction of the developer recovery conveying path 22. When the second conveying screw 28 rotates, its helical blades convey the recovered developer along the extending direction of the conveying path. The developer is moved from the end of the developer recovery conveying path 22 to the intermediate developer conveying path 24. A third conveying screw 30 with helical blades is disposed within the intermediate developer conveying path 24. The third conveying screw 30 is configured such that its axis of rotation is along the extending direction of the intermediate developer conveying path 24. If the third conveying screw 30 rotates, developer is conveyed from one end of the intermediate developer conveying path 24 (where developer is conveyed from the recovery developer conveying path 22) toward the other end. The developer conveyed to the other end is then conveyed to the end of the supply developer conveying path 20. The transfer of developer to the supply developer conveying path 20 can be achieved using a permanent magnet that rotates together with the first conveying screw 26. The permanent magnet is configured as part of a cylinder, which is integrally and coaxially disposed with the first conveying screw 26. The permanent magnet attracts developer within the intermediate developer conveying path 24 and transports it to the supply developer conveying path 20 by the rotation of the cylinder. Within the intermediate developer conveying path 24, the attracted developer is scraped off and delivered to the supply developer conveying path 20.

[0037] The developer transported in developer transport path 18 is conveyed in a serpentine manner. In developer recovery transport path 22, the developer... Figure 2 The developer is conveyed from the front of the paper towards the inside in the intermediate developer conveying path 24, and then again from the inside of the paper towards the front in the developer supply conveying path 20. Hereinafter, the direction of developer conveying in the developer recovery conveying path 22 will be referred to as the "recovery developer conveying direction". Figure 1 , 2 In the diagram, the direction of developer transport is indicated by arrow F.

[0038] The developer retained on the developing roller 14 is scraped off in such a way that its thickness reaches a predetermined value. After passing through the engagement part, the developer particles remaining on the surface of the developing roller 14 move with the rotation of the developing roller 14, and sometimes interact with structures around the developing roller 14 (e.g., Figure 2The part indicated by symbol 31 in the middle) collides. The developer is scattered due to the impact at this time. Furthermore, when the developer falls into the developer collection conveying path 22, it is also scattered due to the impact of the fall. The scattered developer floats in the area around the engagement part. In order to collect the floating developer, a developer discharge device 32 is provided (see reference 32). Figure 3 ).

[0039] Figure 3 This diagram schematically illustrates the structure of the developer discharge device 32. The developer discharge device 32 includes a developer discharge pipe 34 integrally disposed with the developer supply device 13 and a suction fan 36 connected to the developer discharge pipe 34 via piping. The developer discharge pipe 34 is positioned downstream of the engagement portion in the direction of rotational movement of the image holder 12 and the developing roller 14. Air from the area surrounding the engagement portion is drawn through the developer discharge pipe 34 by the suction fan 36. The developer contained in the drawn airflow is captured by a filter 39 disposed upstream of the suction fan 36.

[0040] like Figure 2 As shown, the developer discharge conduit 34 can be formed by a portion of an assembly defining the developer delivery path 18 and a lower cover 38 opposite that portion of the assembly. In the developer delivery path 18, particularly in the developer supply device 13, the drawn air flows through the lower portion of the assembly defining the developer recovery delivery path 22 and the intermediate developer delivery path 24 (in... Figure 2 The area between the middle part (represented by symbol 40) and the lower cover 38.

[0041] exist Figure 3 The lower side is the side opposite to the image holder 12. The developer discharge pipe 34 has a pipe base plate 42, a pipe front wall 44 erected on the edge of the pipe base plate 42 on the image holder side, a pipe rear wall 46 erected on the edge on the side opposite to the image holder 12 of the pipe base plate 42, and pipe side walls 48 erected on the two sides of the pipe base plate 42 in the intersecting direction (C). Figure 2 As shown, the pipe base plate 42 is bent, but... Figure 3 The pipe is shown in its unfolded and flattened state. The pipe base plate 42 may be part of the lower cover 38. The pipe front wall 44, pipe rear wall 46, and pipe side wall 48 may be part of the lower cover 38, and some or all of these may be configured as other components and parts of the developer supply device 13.

[0042] When it is necessary to distinguish between the two pipe sidewalls 48, the upstream pipe sidewall 48 in the direction of developer delivery (F) is referred to as the upstream pipe sidewall 48U, and the downstream pipe sidewall 48 is referred to as the downstream pipe sidewall 48D.

[0043] Suction ports 50 are formed at both ends of the front wall 44 of the pipe in the intersecting direction (C) to draw in developer along with the surrounding air. When it is necessary to distinguish between the two suction ports 50, the suction port 50 on the upstream side in the developer transport direction (F) is referred to as the upstream suction port 50U, and the suction port 50 on the downstream side is referred to as the downstream suction port 50D. The suction ports 50 can be formed away from the pipe sidewall 48 to avoid overlapping with the sealing sheet 16 disposed at the end. The airflow generated by the rotation of the image holder 12 and the developing roller 14 is directed towards the engagement portion and blocked by the narrow engagement portion, thereby further moving along the intersecting direction (C) towards both ends of the engagement portion. The developer floating due to this airflow has a higher concentration at the end of the image holder 12. Suction ports 50 are formed at both ends of the front wall 44 of the pipe corresponding to the areas with high concentrations of floating developer. Alternatively, a suction port can be provided between the two ends.

[0044] An outlet 52 is formed on the downstream side wall 48D of the pipe to discharge developer along with the airflow. The outlet 52 may be formed at a position adjacent to the rear wall 46 of the pipe. The outlet 52 is connected to the suction fan 36, and the airflow from the developer discharge pipe 34 passes through the outlet 52 toward the suction fan 36. The outlet 52 may also be formed on the upstream side wall 48U of the pipe.

[0045] If the developer absorbed accumulates in the developer discharge pipe 34, the airflow around the accumulated developer weakens, causing further developer accumulation. Developer tends to accumulate in areas where the airflow velocity is slowed, such as near the pipe sidewall. In the developer discharge pipe 34 of this embodiment, a side intake port 54 is formed on the downstream sidewall 48D. Figure 4 An example of a side air intake 54 is shown in the figure. Figure 4 yes Figure 1 An enlarged view of the portion indicated by arrow Y. Developer-free air, i.e., clean air, is introduced from the side portion of the developer supply device 13 into the developer discharge pipe 34 through the side air intake 54. The airflow introduced from the side air intake 54 suppresses developer buildup. The side air intake 54 can be formed on the upstream pipe sidewall 48U, or on both pipe sidewalls 48. Furthermore, the discharge port 52 and the side air intake 54 can be formed on the same pipe sidewall 48.

[0046] During the transfer of developer from the developer recovery conveying path 22 to the intermediate developer conveying path 24, a portion of it is swept up and floats. Therefore, in the conveying direction of the developer recovery conveying path 22, the downstream end has more floating developer compared to the upstream end. Due to this difference in the amount of floating developer, the amount of developer drawn from the suction port 50 is greater at the downstream suction port 50D than at the upstream suction port 50U. Consequently, the amount of developer accumulating near the downstream pipe sidewall 48D increases. By providing a side suction port 54 on the downstream pipe sidewall 48D, an airflow is generated in the area where the amount of developer accumulation is greater, thereby suppressing developer accumulation.

[0047] A partition wall 56 is provided in the developer discharge pipe 34, extending from the downstream pipe sidewall 48D toward the upstream pipe sidewall 48U. The partition wall 56 extends between the discharge port 52 and the side suction port 54, with its front end not reaching the upstream pipe sidewall 48U. The partition wall 56 may extend such that the edge of its front end extends beyond the downstream suction port 50D.

[0048] By providing the partition wall 56, the airflow introduced from the side intake port 54 initially flows upstream in the developer recovery conveying direction. When the airflow reaches the edge of the leading edge of the partition wall 56, it changes direction, flowing downstream in the developer recovery conveying direction (F) and reaching the outlet port 52. The partition wall 56 defines a flow path within the developer discharge pipe, guiding the airflow drawn in from the side intake port 54 upstream in the developer recovery conveying direction (F) and then downstream. Compared to the case without the partition wall 56, the airflow from the side intake port 54 to the outlet port 52 experiences higher resistance in the flow path via the partition wall 56. Consequently, the difference in resistance between the airflow and the airflow drawn from the upstream suction port 50U is reduced. This helps to suppress the reduction in the amount of air drawn from the upstream suction port 50U due to the provision of the side intake port 54.

[0049] With the edge of the partition wall 56 extending beyond the downstream suction port 50D, the airflow drawn from the downstream suction port 50D temporarily flows upstream in the developer recovery conveying direction (F) through the partition wall 56, and then changes direction at the front end of the partition wall 56 to flow downstream towards the discharge port 52. The partition wall 56 defines a flow path within the developer discharge pipe that guides the airflow drawn from the downstream suction port 50D upstream in the developer recovery conveying direction (F), and then downstream. By providing the partition wall 56, the path of the airflow drawn from the downstream suction port 50D becomes longer. Consequently, the difference between the resistance experienced by this airflow and the resistance experienced by the airflow drawn from the upstream suction port 50U becomes smaller, thereby reducing the imbalance in the amount of air drawn from the two suction ports 50U and 50D.

[0050] Figure 5 This diagram illustrates the schematic structure of the image forming apparatus 60 included in the aforementioned developing apparatus 10. The image forming apparatus 60 includes an image reading unit 62, an image forming unit 64, and a document transport unit 66. The image reading unit 62 is a component that optically reads the image of a document. The document is placed on a platen glass 68, and the image on the document is optically read by an image reading element 70, which is composed of a CCD or the like. By moving the image reading element 70 along the platen glass 68, the image of the entire document is read. Furthermore, the document can be transported by the document transport unit 66, and during the transport process, the image on the document can be read by the image reading element 70. The document is transported sheet by sheet from the document feed tray 72 of the document transport unit 66 to the document output tray 74, and is read during this process. In this case, the image reading element 70 reads the image of the entire document while remaining stationary.

[0051] The image forming unit 64 forms an image on paper P based on image information read by the image reading unit 62 or image information sent from an external device such as a personal computer. The image forming unit 64 is an apparatus for an electrophotographic system that forms a color image on paper P using four colors of developer. The image forming unit 64 includes image forming units 76Y, 76M, 76C, and 76K that respectively form developer images of yellow (Y), magenta (M), cyan (C), and black (K). The image forming units 76Y, 76M, 76C, and 76K are identical except for the colors they form; especially when color differentiation is not required, Y, M, C, and K are omitted and referred to as image forming unit 76 for explanation. The image forming unit 64 includes: an intermediate transfer belt 78 for transferring the developer images formed by the image forming units 76 of each color; a transfer unit 80 for transferring the developer images from the intermediate transfer belt 78 onto paper P; and a fixing unit 82 for fixing the transferred developer images onto paper P. Furthermore, the image forming unit 64 includes: a paper container 84 for holding paper P; and a paper conveying device 86 for conveying paper P sequentially from the paper container 84 through the transfer unit 80 and the fixing unit 82.

[0052] The developer images of various colors formed by the image forming unit 76 are transferred onto the intermediate transfer belt 78 and overlapped. The developer images on the intermediate transfer belt 78 are conveyed to the transfer unit 80 along with the intermediate transfer belt 78, where they are transferred onto the paper P conveyed by the paper transport device 86. The paper P is further conveyed by the paper transport device 86 to the fixing unit 82, where it is heated and pressurized, thereby fixing the developer image onto the paper P. The paper P with the image formed is conveyed to the paper output tray 88 by the paper transport device 86.

[0053] As representatively shown in yellow, the image forming unit 76Y, the developing apparatus 10 is included in the image forming unit 76. The image forming unit 76 includes a charger 90 that charges the surface of the image holder 12 and an exposure apparatus 92 that irradiates the image holder 12 with light such as a laser to form an electrostatic latent image. The exposure apparatus 92 controls the irradiated light based on image information acquired from the image reading unit 62 or an external device to form the electrostatic latent image. As previously described, a developing agent is supplied from the developing roller 14 to the image holder 12 on which the electrostatic latent image is formed, thereby developing the latent image.

[0054] The developer supply device 13 has a developer discharge pipe 34 for discharging floating developer from the engagement part and its surrounding area. By discharging the floating developer, it is possible to prevent developer from splashing into the image forming apparatus 60, especially the image forming section 64. As a result, contamination of the intermediate transfer belt 78 and the paper transport device 86 can be prevented. As mentioned above, the developing apparatus 10 of this embodiment is configured to prevent blockage of the developer discharge pipe 34, thus reducing the chance of the image forming apparatus 60 stopping due to such blockage.

[0055] The image forming apparatus 60 includes four image forming units 76, each corresponding to one of the four colors of the developer. The number of image forming units corresponds to the number of colors of the developer. When there is only one color of developer, there is only one image forming unit. In the image forming apparatus 60, the developer image formed by the image forming units 76 is indirectly transferred onto the paper P via an intermediate transfer belt 78. Alternatively, the developer image can be directly transferred from the image forming units onto the paper.

[0056] (Postscript) (1)

[0058] A developing apparatus comprising:

[0059] The developing roller holds the developer and rotates;

[0060] Like a retainer, configured to face the developing roller and rotate; and

[0061] The developer discharge channel draws developer from the image holder side and discharges it elsewhere.

[0062] The developer discharge pipe has:

[0063] The front wall of the pipe is disposed on the side of the image holder, and suction ports for suctioning developer are formed at both ends in the cross direction that intersects the rotational movement direction of the developing roller.

[0064] The rear wall of the pipe, located on the side of the front wall of the pipe opposite to the image holder; and

[0065] Two pipe sidewalls, located at the ends on both sides of the intersection direction.

[0066] On one of the two pipe sidewalls, a discharge port for discharging developer is formed at a position adjacent to the rear wall of the pipe.

[0067] An air intake port for drawing air is formed on one of the two pipe sidewalls. (2)

[0069] According to the developing apparatus described in (1), wherein,

[0070] The outlet and the side air intake are formed on the downstream side wall of the two pipes, which is located downstream of the conveying direction of the developer recovery conveying path. The developer recovery conveying path will recover the developer that is not developed onto the image holder by the developing roller and convey it along the intersecting direction. (3)

[0072] According to the developing apparatus described in (2), wherein,

[0073] The developer discharge pipe has a partition wall that extends from the outlet and the side intake of the downstream pipe sidewall toward the opposite pipe sidewall but does not reach the opposite pipe sidewall. (4)

[0075] According to the developing apparatus described in (3), wherein,

[0076] The edge of the front end of the partition wall is located upstream of the conveying direction of the recoverable developer conveying path in the intersecting direction, compared to the suction port located on the downstream side of the pipe sidewall. (5)

[0078] According to the developing apparatus described in (2), wherein,

[0079] An air guiding path is defined within the developer discharge pipe, which temporarily guides the air drawn from the side air intake towards the upstream side in the conveying direction of the recovered developer conveying path, and then guides it towards the discharge outlet. (6)

[0081] According to the developing apparatus described in (5), wherein,

[0082] The air guiding path temporarily guides the air drawn from the suction port located on the downstream side of the pipe wall towards the upstream side in the conveying direction of the recovered developer conveying path, and then guides it towards the discharge port. (7)

[0084] An image forming apparatus comprising:

[0085] The developing apparatus as described in any one of (1) to (6);

[0086] The charger charges the surface of the image holder.

[0087] An exposure apparatus uses light to expose the charged image holder, thereby forming an electrostatic latent image on the image holder;

[0088] The transfer unit directly or indirectly transfers the developer image obtained by developing the electrostatic latent image using developer supplied from the developing roller onto paper.

[0089] The fixing unit fixes the developer image transferred onto the paper onto the paper; and

[0090] A conveying device for conveying the paper through the transfer unit and the fixing unit.

[0091] According to the structure involved in (1), the accumulation of developer in the flow path for recovering developer can be suppressed compared to the case where no side air intake is formed on the side wall of the pipe.

[0092] According to the structure involved in (2), the accumulation of developer near the downstream sidewall of the pipe can be suppressed.

[0093] According to the structure involved in (3), compared with the case where the developer discharge pipe does not have a partition wall, the amount of air drawn from the suction port on the upstream side in the conveying direction of the developer recovery conveying path is increased.

[0094] According to the structure involved in (4), compared with the case where the partition wall does not extend beyond the suction port on the downstream side, the degree of imbalance in the amount of air drawn from the two suction ports is reduced.

[0095] According to the structure involved in (5), compared to the case where the air drawn from the side air intake is not predetermined to be temporarily guided towards the upstream side and then guided towards the downstream side, the amount of air drawn from the upstream air intake in the transport direction of the developer transport path is greater.

[0096] According to the structure involved in (6), compared to the case where the air drawn from the downstream suction port is not predetermined to be temporarily guided towards the upstream side and then guided towards the downstream side, the imbalance in the amount of air drawn from the two suction ports is reduced.

[0097] According to the structure involved in (7), compared with the case where the developing apparatus described in any of the structures in (1) to (6) is not present, the chance of the image forming apparatus stopping is reduced.

[0098] The embodiments of the present invention described above are provided for illustrative purposes. Furthermore, these embodiments do not encompass the entirety of the invention, nor do they limit the invention to the disclosed methods. It will be apparent to those skilled in the art that various modifications and variations will be readily understood. These embodiments were chosen and described to most readily explain the principles and applications of the invention. Thus, those skilled in the art can understand the invention through various modifications that are assumed to be optimized for specific uses of various embodiments. The scope of the invention is defined by the foregoing claims and their equivalents.

Claims

1. A developing apparatus, comprising: The developing roller holds the developer and rotates; Like a holder, configured to face the developing roller and rotate; and The developer discharge channel draws developer from the image holder side and discharges it elsewhere. The developer discharge pipe has: The front wall of the pipe is disposed on the side of the image holder, and suction ports for suctioning developer are formed at both ends in the cross direction that intersects the rotational movement direction of the developing roller. The rear wall of the pipe, located on the side of the front wall of the pipe opposite to the image holder; and Two pipe sidewalls, located at the ends on both sides of the intersection direction. On one of the two pipe sidewalls, a discharge port for discharging developer is formed at a position adjacent to the rear wall of the pipe. An air intake port for drawing air is formed on one of the two pipe sidewalls.

2. The developing apparatus according to claim 1, wherein, The outlet and the side air intake are formed on the downstream side wall of the two pipes, which is located downstream of the conveying direction of the developer recovery conveying path. The developer recovery conveying path will recover the developer that is not developed onto the image holder by the developing roller and convey it along the intersecting direction.

3. The developing apparatus according to claim 2, wherein, The developer discharge pipe has a partition wall that extends from the outlet and the side intake of the downstream pipe sidewall toward the opposite pipe sidewall but does not reach the opposite pipe sidewall.

4. The developing apparatus according to claim 3, wherein, The edge of the front end of the partition wall is located upstream of the conveying direction of the recoverable developer conveying path in the intersecting direction, compared to the suction port located on the downstream side of the pipe sidewall.

5. The developing apparatus according to claim 2, wherein, An air guiding path is defined within the developer discharge pipe, which temporarily guides the air drawn from the side air intake towards the upstream side in the conveying direction of the recovered developer conveying path, and then guides it towards the discharge outlet.

6. The developing apparatus according to claim 5, wherein, The air guiding path temporarily guides the air drawn from the suction port located on the downstream side of the pipe wall towards the upstream side in the conveying direction of the recovered developer conveying path, and then guides it towards the discharge port.

7. An image forming apparatus comprising: The developing apparatus according to any one of claims 1 to 6; The charger charges the surface of the image holder. An exposure apparatus uses light to expose the charged image holder, thereby forming an electrostatic latent image on the image holder; The transfer unit directly or indirectly transfers the developer image obtained by developing the electrostatic latent image using developer supplied from the developing roller onto paper. The fixing section fixes the developer image transferred onto the paper onto the paper; and A conveying device for conveying the paper through the transfer unit and the fixing unit.

Images