Developing device

Abstract

To suppress the accumulation of developer in a developer discharge duct for sucking and discharging the developer from a nip and its peripheral area.SOLUTION: The developer discharge duct 34 has a duct front 48U 44 which is arranged on the image holding body side and in which sucking ports for sucking the developer are formed at both end parts in the crossing direction (C), a duct rear 48D 46 which is positioned on the opposite side of the image holding body of the duct front wall 44, and two duct side walls side walls positioned at both ends in the crossing direction (C). On the 48D of the downstream duct sidewall, a discharge port 52 for discharging the developer is formed at a position adjacent to the duct rear wall, and a side surface suction port 54 for sucking air is formed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a developing device. [Background technology]

[0002] An electrophotographic image forming apparatus has a developing device including an image carrier and a developer supplying device that supplies developer to the image carrier. The developing device includes a developing roll that holds developer on its surface. The developer held on the developing roll transfers to the image carrier, developing the electrostatic latent image on the image carrier. Some of the developer that is not used for development floats near the developing roll and the image carrier. Techniques for recovering this floating developer are described in Patent Documents 1 and 2 below.

[0003] Patent Document 2 listed below discloses a technology for discharging developer accumulated in a flow path that collects floating developer. In this document, when images are not being formed, air is introduced into the flow path from an intake port that is different from that used when images are being formed, to generate a strong airflow. This airflow then discharging the accumulated developer from the flow path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-177604 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-125148 Summary of the Invention [Problem to be solved by the invention]

[0005] When developer accumulates in the flow path that collects the developer along with the airflow, the flow path narrows and may become clogged in some cases. In recent years, there has been a demand for faster image forming devices, and with this increase in speed, the amount of collected developer increases, increasing the possibility of the flow path becoming clogged.

[0006] An object of the present invention is to suppress the accumulation of developer in a flow path that recovers the developer. [Means for solving the problem]

[0007] The invention of claim 1 is a developing device including: a developing roll that rotates while holding developer; an image carrier that is arranged opposite the developing roll and rotates; and a developer discharge duct that sucks developer from the image carrier side and discharges it elsewhere, the developer discharge duct having a duct front wall that is arranged on the image carrier side and has suction ports for sucking developer formed at both ends in a cross direction that intersects the direction of rotational movement of the developing roll; a duct rear wall that is located on the opposite side of the duct front wall from the image carrier; and two duct side walls that are located at both ends in the cross direction, wherein one of the two duct side walls has a discharge port for discharging developer formed adjacent to the duct rear wall, and one of the two duct side walls has a side air intake port for sucking air.

[0008] The invention of claim 2 is a developing device as described in claim 1, in which the discharge outlet and the side air intake are formed in the downstream duct side wall of the two duct side walls, which is located downstream in the transport direction of a recovered developer transport path that recovers the remaining developer that has not been developed from the developing roll to the image carrier and sends it along the intersecting direction.

[0009] The invention of claim 3 is a developing device as described in claim 2, in which the developer discharge duct has a partition wall that extends from a position between the discharge outlet and the side air intake port on the downstream duct side wall toward the opposite duct side wall, but does not reach the opposite duct side wall.

[0010] The invention of claim 4 is a developing device described in claim 3, in which the tip edge of the partition wall is located upstream of the downstream suction port, which is the suction port located on the downstream duct side wall side, in the cross direction in the transport direction of the recovered developer transport path.

[0011] The invention of claim 5 is a developing device as described in claim 2, in which an air guide path is defined within the developer discharge duct that first guides the air sucked in from the side air intake port toward the upstream side in the transport direction of the recovered developer transport path, and then guides it toward the discharge outlet.

[0012] The invention of claim 6 is a developing device described in claim 5, in which the air guide path first guides the air sucked from the downstream suction port, which is the suction port located on the downstream duct side wall, toward the upstream side in the transport direction of the recovered developer transport path, and then guides it toward the discharge port.

[0013] The invention of claim 7 is an image forming apparatus comprising: a developing device according to any one of claims 1 to 6; a charger that charges the surface of the image carrier; an exposure device that exposes the charged image carrier to light and forms an electrostatic latent image on the image carrier; a transfer unit that transfers a developer image, in which the electrostatic latent image is developed with developer supplied from the developing roll, directly or indirectly from the developing roll to paper; a fixing unit that fixes the developer image transferred onto the paper to the paper; and a transport device that transports the paper so as to pass through the transfer unit and the fixing unit. [Effects of the Invention]

[0014] According to the invention of claim 1, accumulation of developer in the flow path that recovers the developer is suppressed compared to when no side intake port is formed in the duct side wall.

[0015] According to the invention as set forth in claim 2, accumulation of developer in the vicinity of the downstream duct side wall is suppressed.

[0016] According to the invention of claim 3, the amount of air sucked from the suction port on the upstream side in the transport direction of the recovered developer transport path is greater than when the developer discharge duct does not have a partition wall.

[0017] According to the invention of claim 4, the degree of imbalance in the amount of air sucked from the two suction ports is reduced compared to when the partition wall does not extend beyond the downstream suction port.

[0018] According to the invention of claim 5, the amount of air sucked in from the upstream suction port in the transport direction of the recovered developer transport path is greater than when there is no predetermined path to guide the air sucked in from the side air intake port first upstream and then downstream.

[0019] According to the invention of claim 6, the degree of imbalance in the amount of air sucked in from the two suction ports is reduced compared to when there is no predetermined path to guide the air sucked in from the downstream suction port first upstream and then downstream.

[0020] According to the seventh aspect of the invention, compared to a case where the developing device according to any one of the first to sixth aspects is not provided, the image forming apparatus is less likely to stop operating. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a perspective view showing the appearance of a developer supply device of the developing device according to the present embodiment. [Figure 2] 2 is a cross-sectional view of the developing device of the present embodiment taken along line AA shown in FIG. 1. [Figure 3] FIG. 4 is a diagram schematically illustrating the structure of a developer discharge duct. [Figure 4] FIG. 2 is an external view showing a side air intake port of the developer supply device and its surroundings. [Figure 5] FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are diagrams showing the schematic configuration of a developing device 10 provided in an electrophotographic image forming apparatus. The developing device 10 includes an image carrier 12 and a developer supply device 13 that supplies developer to the image carrier 12. FIG. 1 is a diagram showing the appearance of the developer supply device 13. FIG. 2 is a cross-sectional view taken along line AA shown in FIG. 1, showing a part of the image carrier 12 in addition to the developer supply device 13. The up-down direction in FIGS. 1 and 2 corresponds to the direction of gravity when the developing device 10 is installed in the image forming apparatus.

[0023] The developing device 10 is disposed within the image forming apparatus with the image carrier 12 and the developer supply device 13 facing each other. An electrostatic latent image is formed on the surface of the image carrier 12, and the electrostatic latent image is developed with a developer supplied from the developer supply device 13. The developer image formed on the surface of the image carrier 12 by development is transferred onto a recording medium such as paper or onto an intermediate transfer body. The developer image transferred to the intermediate transfer body is later transferred onto a recording medium. The developer may be toner. The image carrier 12 is, for example, a cylindrical photoreceptor roll that rotates around the center line of the cylinder. The direction of rotation of the image carrier 12 is indicated by arrow R in FIG. 2. Due to this rotation, developer images are sequentially formed on the image carrier 12 at a position facing the developer supply device 13, and the developer images are then sent to a position where they are transferred to a recording medium.

[0024] The developer supply device 13 includes a developing roll 14 that holds the developer to be supplied to the image carrier 12. The developing roll 14 is disposed facing the image carrier 12. The developing roll 14 is cylindrical, and its center line is disposed along the direction of the center line of the cylindrical image carrier 12. The developing roll 14 is disposed close to the image carrier 12, forming a gap between it and the image carrier 12. The area sandwiched between the developing roll 14 and the image carrier 12 is hereinafter referred to as the "nip." The developing roll 14 rotates around its center line. This rotation direction is such that the directions of movement of the surfaces of the developing roll 14 and the image carrier 12 are aligned at the portion facing the image carrier 12. The rotation directions of the image carrier 12 and the developing roll 14 may be opposite to each other. At the portion facing the developing roll 14 and the image carrier 12, the direction in which the surfaces move as they rotate is hereinafter referred to as the "direction of rotational movement," and the direction intersecting this direction is hereinafter referred to as the "cross direction." The cross direction is also the direction in which the centerline of the developer roll 14 extends.

[0025] The developing roll 14 uses magnetic force to attract and hold developer on its surface. As the developing roll 14 rotates, the developer is supplied to the nip and develops the electrostatic latent image on the image carrier 12. Seal pieces 16 are arranged at both ends of the nip in the cross direction (see Figure 1). The seal pieces 16 prevent the developer floating in the nip and its surrounding area from flowing out of this area in the cross direction.

[0026] The developer supply device 13 has a developer transport path 18 that supplies developer to the developing roll 14 and collects developer from the developing roll 14. The developer transport path 18 includes three linear developer transport paths 20, 22, and 24. Note that the number of developer transport paths 18 is not limited to three. Each of the three linear developer transport paths 20, 22, and 24 extends along the intersecting direction and agitates and transports the developer along the intersecting direction. The developer is charged by the agitation. The developer transport path 18 further includes a transfer transport path (not shown) that transfers the developer between the linear developer transport paths 20, 22, and 24. The developer transport path 20 is a transport path that supplies developer to the developing roll 14 and is hereinafter referred to as the supply developer transport path 20. In the supply developer transport path 20, the developer is transported along the intersecting direction and supplied to the developing roll 14. The developer transport path 22 is a transport path that transports the developer recovered from the developing roll 14, and is hereinafter referred to as the recovered developer transport path 22. The developer transport path 24 is a transport path that sends out the developer transferred from the recovered developer transport path 22 toward the supply developer transport path 20, and is hereinafter referred to as the intermediate developer transport path 24.

[0027] A first transport screw 26 having a helical blade is disposed within the supply developer transport path 20. The first transport screw 26 is disposed so that its rotation axis is aligned with the extension direction of the supply developer transport path 20. When the first transport screw 26 rotates, its helical blade transports the developer along the extension direction of the transport path, and in the process, the developer is sent toward the developing roll 14 over the entire length of the developing roll 14. A second transport screw 28 having a helical blade is disposed within the recovered developer transport path 22. The second transport screw 28 is disposed so that its rotation axis is aligned with the extension direction of the recovered developer transport path 22. When the second transport screw 28 rotates, its helical blade transports the recovered developer along the extension direction of the transport path. The developer is transferred to the intermediate developer transport path 24 at the end of the recovered developer transport path 22. A third transport screw 30 having a spiral blade is disposed within the intermediate developer transport path 24. The third transport screw 30 is disposed so that its rotation axis is aligned with the extension direction of the intermediate developer transport path 24. When the third transport screw 30 rotates, the developer is transported from the end of the intermediate developer transport path 24 where the developer is delivered from the recovered developer transport path 22 to the other end. The developer delivered to the other end is delivered to the end of the supply developer transport path 20. A permanent magnet rotating together with the first transport screw 26 may be used to transport the developer to the supply developer transport path 20. The permanent magnet is provided as part of a cylindrical body coaxially and integrally with the first transport screw 26. The permanent magnet attracts the developer in the intermediate developer transport path 24 and transports it to the supply developer transport path 20 as the cylindrical body rotates. In the supply developer transport path 20, the adsorbed developer is scraped off and sent out to the supply developer transport path 20.

[0028] The developer transported through the developer transport path 18 is transported in a serpentine manner. In the recovered developer transport path 22, the developer is transported from the front to the back of the paper in FIG. 2, in the intermediate developer transport path 24, the developer is transported from the back to the front of the paper, and in the supply developer transport path 20, the developer is transported again from the front to the back of the paper. The transport direction of the developer in the recovered developer transport path 22 will hereinafter be referred to as the "recovered developer transport direction." The recovered developer transport direction is indicated by arrow F in FIGS. 1 and 2.

[0029] The excess developer held on the developing roll 14 is scraped off so that the thickness of the developer becomes a predetermined value. The developer spikes remaining on the surface of the developing roll 14 after passing through the nip move as the developing roll 14 rotates, and some of them collide with structures around the developing roll 14 (for example, the portion indicated by reference numeral 31 in FIG. 2). The developer is scattered by the impact at this time. The developer is also scattered by the impact when it falls into the recovered developer transport path 22. The scattered developer floats in the area around the nip. A developer discharge device 32 is provided to collect the floating developer (see FIG. 3).

[0030] 3 is a diagram schematically illustrating the configuration of the developer discharge device 32. The developer discharge device 32 includes a developer discharge duct 34 that is provided integrally with the developer supply device 13, and a suction fan 36 that is connected to the developer discharge duct 34 via piping. The developer discharge duct 34 is disposed downstream of the nip in the direction of rotational movement of the image carrier 12 and the developing roll 14. Air in the area around the nip is sucked in by the suction fan 36 through the developer discharge duct 34. The developer contained in the sucked airflow is collected in a filter 39 that is disposed upstream of the suction fan 36.

[0031] 2, the developer discharge duct 34 may be formed by a part of a component that defines the developer transport path 18 and a lower cover 38 that faces this part. In the developer transport path 18, particularly in this developer supply device 13, the sucked air flows through the area sandwiched between the lower part (the part indicated by reference numeral 40 in FIG. 2) of the component that defines the recovered developer transport path 22 and the intermediate developer transport path 24 and the lower cover 38.

[0032] In FIG. 3 , the lower side is the side facing the image carrier 12. The developer discharge duct 34 has a duct bottom plate 42, a duct front wall 44 erected at the edge of the duct bottom plate 42 on the image carrier side, a duct rear wall 46 erected at the edge of the duct bottom plate 42 opposite the image carrier 12, and duct side walls 48 erected at both edges of the duct bottom plate 42 in the intersecting direction (C). As shown in FIG. 2 , the duct bottom plate 42 is curved, but in FIG. 3 it is shown in an unfolded, flat state. The duct bottom plate 42 may be part of the lower cover 38. The duct front wall 44, the duct rear wall 46, and the duct side walls 48 may be part of the lower cover 38, or some or all of them may be provided as part of other components of the developer supply device 13.

[0033] When it is necessary to distinguish between the two duct side walls 48, the upstream duct side wall 48 in the recovered developer transport direction (F) is referred to as the upstream duct side wall 48U, and the downstream duct side wall 48 is referred to as the downstream duct side wall 48D.

[0034] The duct front wall 44 has suction ports 50 formed at both ends in the cross direction (C) that suck in developer along with surrounding air. When it is necessary to distinguish between the two suction ports 50, the upstream suction port 50 in the recovered developer transport direction (F) is referred to as the upstream suction port 50U, and the downstream suction port 50 is referred to as the downstream suction port 50D. The suction ports 50 may be located away from the duct side wall 48 so as not to overlap with the seal pieces 16 located at the ends. The airflow caused by the rotation of the image carrier 12 and the developing roll 14 flows toward the nip and is blocked by the narrow nip, further moving toward both ends of the nip along the cross direction (C). The developer suspended by this airflow becomes concentrated at the ends of the image carrier 12. The suction ports 50 are formed at both ends of the duct front wall 44, corresponding to the regions where the concentration of the suspended developer is high. Additional suction ports may be provided between the ends.

[0035] The downstream duct side wall 48D has a discharge port 52 formed therein, which discharges the developer together with the airflow. The discharge port 52 may be formed at a position adjacent to the duct rear wall 46. The discharge port 52 is connected to the suction fan 36, and the airflow from the developer discharge duct 34 passes through the discharge port 52 toward the suction fan 36. The discharge port 52 may be formed in the upstream duct side wall 48U.

[0036] When the sucked developer accumulates in the developer discharge duct 34, the airflow weakens around the accumulated developer, causing further accumulation of developer. Developer tends to accumulate in areas where the airflow speed is slow, such as near the duct side walls. In this embodiment, the developer discharge duct 34 has a side air intake 54 formed in the downstream duct side wall 48D. FIG. 4 shows an example of the side air intake 54. FIG. 4 is an enlarged view of the portion indicated by arrow Y in FIG. 1. Through the side air intake 54, developer-free air, i.e., clean air, is introduced into the developer discharge duct 34 from the side of the developer supply device 13. The airflow introduced through the side air intake 54 prevents developer accumulation. The side air intake 54 may be formed in the upstream duct side wall 48U or in both duct side walls 48. Additionally, the outlet 52 and the side intake 54 may be formed in the same duct side wall 48 .

[0037] As the developer is transferred from the recovered developer transport path 22 to the intermediate developer transport path 24, a portion of the developer is rolled up and floats. As a result, the downstream end of the recovered developer transport path 22 in the transport direction has more floating developer than the upstream end. Due to the difference in the amount of floating developer described above, the amount of developer sucked through the suction port 50 is greater at the downstream suction port 50D than at the upstream suction port 50U. As a result, the amount of developer that accumulates near the downstream duct side wall 48D increases. By providing a side air intake 54 in the downstream duct side wall 48D, an airflow is generated in the area where the amount of developer accumulation increases, suppressing the accumulation of developer.

[0038] The developer discharge duct 34 is provided with a partition wall 56 extending from the downstream duct side wall 48D toward the upstream duct side wall 48U. The partition wall 56 extends from between the discharge port 52 and the side air intake port 54, and its tip does not reach the upstream duct side wall 48U. The partition wall 56 may extend so that its tip edge exceeds the downstream suction port 50D.

[0039] By providing the partition wall 56, the airflow introduced through the side air intake port 54 first flows upstream in the recovered developer transport direction. When the airflow reaches the edge of the partition wall 56, it changes direction and flows downstream in the recovered developer transport direction (F) until it reaches the discharge port 52. The partition wall 56 defines a flow path within the developer discharge duct that first directs the airflow drawn in through the side air intake port 54 upstream in the recovered developer transport direction (F) and then guides it downstream. The partition wall 56 increases the resistance that the airflow from the side air intake port 54 to the discharge port 52 experiences from the flow path compared to when the partition wall 56 is not provided. This reduces the difference in resistance that the airflow drawn in through the upstream suction port 50U experiences from the flow path. Furthermore, the provision of the side air intake port 54 prevents a decrease in the amount of air drawn through the upstream suction port 50U.

[0040] When the partition wall 56 extends beyond the downstream suction port 50D, the airflow sucked through the downstream suction port 50D flows upstream in the recovered developer transport direction (F) due to the partition wall 56, then changes direction at the tip of the partition wall 56 and flows downstream toward the discharge port 52. The partition wall 56 defines a flow path within the developer discharge duct that first guides the airflow sucked through the downstream suction port 50D upstream in the recovered developer transport direction (F) and then downstream. The partition wall 56 extends the path of the airflow sucked through the downstream suction port 50D. This reduces the difference between the resistance experienced by this airflow and the resistance experienced by the airflow sucked through the upstream suction port 50U, thereby reducing the imbalance in the amount of air sucked through the two suction ports 50U and 50D.

[0041] FIG. 5 is a diagram showing a schematic configuration of an image forming apparatus 60 equipped with the aforementioned developing device 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 optically reads an image of a document. The document is placed on a platen glass 68, and an image reading element 70, such as a CCD, optically reads the image on the document. The image reading element 70 is moved along the platen glass 68 to read the entire image of the document. Alternatively, the document may be transported by the document transport unit 66, and the image on the document may be read by the image reading element 70 during the transport process. The document is transported one sheet at a time from a document feed tray 72 of the document transport unit 66 to a document discharge tray 74, and is read during the transport process. In this case, the image reading element 70 remains stationary while the entire image of the document is read.

[0042] Image forming unit 64 forms an image on paper P based on image information read by image reading unit 62 or image information sent from an external device such as a personal computer. Image forming unit 64 is an electrophotographic device that forms a color image on paper P using four color developers. Image forming unit 64 includes image forming units 76Y, 76M, 76C, and 76K that form developer images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Image forming units 76Y, 76M, 76C, and 76K are the same except for the color they form. When there is no need to distinguish between colors, they will be referred to as image forming units 76, omitting the Y, M, C, and K. Image forming unit 64 includes an intermediate transfer belt 78 onto which the developer images formed by each image forming unit 76 are transferred, a transfer unit 80 that transfers the developer images from intermediate transfer belt 78 onto paper P, and a fixing unit 82 that fixes the transferred developer images onto paper P. Furthermore, the image forming unit 64 includes a paper container 84 that stores paper P, and a paper transport device 86 that transports paper P from the paper container 84 one sheet at a time so that the paper P passes through the transfer unit 80 and the fixing unit 82 in that order.

[0043] The developer images of each color formed by the image forming units 76 are transferred and superimposed on an intermediate transfer belt 78. The developer images on the intermediate transfer belt 78 are sent to a transfer section 80 as the intermediate transfer belt 78 rotates, where they are transferred onto a sheet of paper P that has been conveyed by a paper conveying device 86. The sheet of paper P is further conveyed by the paper conveying device 86 to a fixing section 82, where the developer images are fixed to the sheet of paper P by heating and pressure. The sheet of paper P on which the image has been formed is sent onto a paper output tray 88 by the paper conveying device 86.

[0044] As representatively shown in the yellow image forming unit 76Y, the developing device 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 carrier 12, and an exposure device 92 that irradiates the image carrier 12 with light such as laser light to form an electrostatic latent image. The exposure device 92 controls the irradiated light based on image information obtained from the image reading unit 62 or an external device, and forms the electrostatic latent image. As described above, a developer is supplied from the developing roll 14 onto the image carrier 12 on which the electrostatic latent image has been formed, and the latent image is developed.

[0045] The developer supply device 13 has a developer discharge duct 34 for discharging floating developer from the nip and its surrounding area. Discharging floating developer prevents the developer from scattering inside the image forming device 60, particularly the image forming unit 64. This prevents contamination of the intermediate transfer belt 78 and the paper transport device 86. As described above, the developing device 10 of this embodiment is configured to prevent clogging of the developer discharge duct 34, thereby reducing the chances of the image forming device 60 stopping due to such clogging.

[0046] The image forming device 60 is provided with four image forming units 76 corresponding to the four colors of developer. The number of image forming units corresponds to the number of colors of developer. If the developer is of one color, there is one image forming unit. In the image forming device 60, the developer image formed by the image forming unit 76 is indirectly transferred to paper P via an intermediate transfer belt 78. Alternatively, the developer image may be transferred directly from the image forming unit to paper.

[0047] (Addendum) (((1))) a developing roll that holds a developer and rotates; an image carrier that is disposed opposite the developing roll and rotates; a developer discharge duct that sucks developer from the image carrier side and discharges it to another location, a duct front wall disposed on the image carrier side, the duct front wall having suction ports formed at both ends in a direction intersecting the direction of rotation of the developing roll for sucking in the developer; a duct rear wall located on the opposite side of the duct front wall from the image carrier; Two duct side walls located at both ends in the crossing direction; and one of the two duct side walls has a discharge port formed in a position adjacent to the duct rear wall for discharging the developer; One of the two duct side walls has a side air intake port formed therein for sucking air. a developer discharge duct; A developing device comprising: (((2))) The developing device described in (((1))), wherein the outlet and the side intake port are formed in the downstream duct side wall, of the two duct side walls, which is located downstream in the transport direction of a recovered developer transport path that recovers the developer that remains from the developing roll and is not developed onto the image carrier and sends it along the intersecting direction. (((3))) The developing device described in (((2))), wherein the developer discharge duct has a partition wall that extends from a position between the discharge port and the side air intake port on the downstream duct side wall toward the opposite duct side wall, but does not reach the opposite duct side wall. (((4))) A developing device as described in (((3))), wherein the tip edge of the partition wall is located upstream in the conveying direction of the recovered developer conveying path in the cross direction from the downstream suction port, which is the suction port located on the downstream duct side wall side. (((5))) A developing device as described in (((2))), in which an air guide path is defined within the developer discharge duct that first guides the air sucked in from the side air intake port toward the upstream side in the transport direction of the recovered developer transport path, and then guides it toward the discharge port. (((6))) The developing device described in (((5))), wherein the air guide path guides the air sucked from the downstream suction port, which is the suction port located on the downstream duct side wall side, toward the upstream side in the transport direction of the recovered developer transport path, and then guides it toward the discharge port. (((7))) A developing device according to any one of (((1))) to (((6))), a charger for charging the surface of the image carrier; an exposure device that exposes the charged image carrier to light to form an electrostatic latent image on the image carrier; a transfer unit that transfers a developer image, which is formed by developing the electrostatic latent image with the developer supplied from the developing roll, directly or indirectly from the developing roll to a sheet of paper; a fixing unit that fixes the developer image transferred onto the paper; a conveying device that conveys the paper so that the paper passes through the transfer unit and the fixing unit; An image forming apparatus comprising:

[0048] According to the configuration (((1))), accumulation of developer in the flow path that recovers the developer is suppressed compared to when no side intake port is formed in the duct side wall. According to the configuration (((2))), accumulation of developer in the vicinity of the downstream duct side wall is suppressed. According to the configuration (((3))), the amount of air sucked from the suction port on the upstream side in the transport direction of the recovered developer transport path is greater than when the developer discharge duct does not have a partition wall. The configuration according to (((4))) reduces the degree of imbalance in the amount of air drawn through the two suction ports compared to when the partition wall does not extend beyond the downstream suction port. According to the configuration of (((5))), the amount of air sucked in from the upstream suction port in the transport direction of the recovered developer transport path is greater than when there is no predetermined path to guide the air sucked in from the side air intake port first upstream and then downstream. According to the configuration of (((6))), the degree of imbalance in the amount of air sucked in from the two suction ports is reduced compared to when there is no predetermined path to guide the air sucked in from the downstream suction port first upstream and then downstream. According to the configuration of (((7))), the image forming apparatus is less likely to stop operating than when it is not equipped with a developing device described in any one of the configurations of (((1))) to (((6))). [Explanation of symbols]

[0049] 10 developing device, 12 image carrier, 13 developer supply device, 14 developing roll, 16 seal piece, 18 developer transport path, 20 supplied developer transport path, 22 recovered developer transport path, 24 intermediate developer transport path, 32 developer discharge device, 34 developer discharge duct, 38 lower cover, 40 lower portion, 42 duct bottom plate, 44 duct front wall, 46 duct rear wall, 48 duct side wall, 48U upstream duct side wall, 48D downstream duct side wall, 50 suction port, 50U upstream suction port, 50D downstream suction port, 52 discharge port, 54 side intake port, 56 partition wall.

Claims

1. a developing roll that holds a developer and rotates; an image carrier that is disposed opposite the developing roll and rotates; a developer discharge duct that sucks developer from the image carrier side and discharges it to another location, a duct front wall disposed on the image carrier side, the duct front wall having suction ports formed at both ends in a direction intersecting the direction of rotation of the developing roll for sucking in the developer; a duct rear wall located on the opposite side of the duct front wall from the image carrier; Two duct side walls located at both ends in the crossing direction; and one of the two duct side walls has a discharge port formed in a position adjacent to the duct rear wall for discharging the developer; One of the two duct side walls has a side air intake port formed therein for sucking air. a developer discharge duct; A developing device comprising:

2. 2. The developing device according to claim 1, wherein the discharge port and the side air intake port are formed in the downstream duct side wall, of the two duct side walls, which is located downstream in the transport direction of a recovered developer transport path that recovers the developer that remains from the developing roll and has not been developed onto the image carrier and sends it along the intersecting direction.

3. 3. The developing device according to claim 2, wherein the developer discharge duct has a partition wall that extends from a position between the discharge port and the side air intake port on the downstream duct side wall toward the opposite duct side wall, but does not reach the opposite duct side wall.

4. 4. The developing device according to claim 3, wherein the tip edge of the partition wall is located upstream of the downstream suction port, which is the suction port located on the downstream duct side wall side, in the cross direction in the transport direction of the recovered developer transport path.

5. 3. The developing device according to claim 2, wherein an air guide path is provided within the developer discharge duct to guide the air sucked through the side air intake port toward the upstream side in the transport direction of the recovered developer transport path, and then guide the air toward the discharge port.

6. 6. The developing device according to claim 5, wherein the air guide path guides the air sucked from the downstream suction port, which is the suction port located on the downstream duct side wall side, toward the upstream side in the transport direction of the recovered developer transport path, and then guides it toward the discharge port.

7. The developing device according to any one of claims 1 to 6, a charger for charging the surface of the image carrier; an exposure device that exposes the charged image carrier to light to form an electrostatic latent image on the image carrier; a transfer section that transfers a developer image, obtained by developing the electrostatic latent image with the developer supplied from the developing roll, directly or indirectly from the developing roll to a sheet of paper; a fixing unit that fixes the developer image transferred onto the paper; a conveying device that conveys the paper so that the paper passes through the transfer unit and the fixing unit; An image forming apparatus comprising:

Images