Developing device and image forming apparatus including the same

Abstract

To provide a developing device that can sufficiently stir developer to prevent the occurrence of poorly charged toner, and an image forming apparatus including the same.SOLUTION: A developing device 2 including a developing roller 21 has a first chamber 84 provided with a first conveying member 22 that conveys developer in one direction, and a second chamber 85 provided with a second conveying member 23 that conveys the developer in the other direction and the developing roller 21 above the second conveying member 23. The first conveying member 22 includes a first rotation shaft 24 and a spiral first blade 26. The second conveying member 23 includes a second rotation shaft 25 and a spiral second blade 27. The first chamber 84 and the second chamber 85 form a circulation path of the developer. A top face rib 82 is formed on a ceiling part 81a of the first chamber 84 so as to extend toward the first conveying member 22. In a plan view seen from the side of the ceiling part 81a, the top face rib 82 intersects the first rotation shaft 24 at an angle larger than 0 degree and smaller than 90 degrees.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a developing device that accommodates a developer containing toner, and an image forming apparatus including the same. [Background technology]

[0002] Commonly used image forming apparatuses employ electrophotography, such as copying machines, facsimile machines, printers, and multifunction machines. In such electrophotographic image forming apparatuses, an electrostatic latent image formed on the surface of a photosensitive drum is developed with toner to form a toner image, which is then transferred to paper and fixed with heat to form an image on the paper.

[0003] Therefore, the developing device contains a developer containing toner to form a toner image. Some of these developing devices have a circulation chamber that contains and circulates the developer, and a number of conveying screws for circulating the contained developer. In such a developing device having a circulation chamber, the developer contained in the circulation chamber is triboelectrically charged by rotating the multiple conveying screws while circulating the developer in the circulation chamber, and the charged toner is supplied to the electrostatic latent image on the surface of the photosensitive drum to form a toner image. The circulation chamber is provided with a replenishing section for replenishing the toner lost as a result of the formation of the toner image on the photosensitive drum.

[0004] Here, when toner is replenished to the circulation chamber, the position of the developer surface (the free surface of the developer contained in the development chamber) in the circulation chamber may temporarily become higher than the conveying screw. In such a case, the new toner replenished from the replenishing section is not sufficiently stirred by the conveying screw, so that the charge amount decreases, and there is a risk of developing a non-image portion of the electrostatic latent image that should not be developed, resulting in a defective image. As a development device that solves such a problem, for example, Patent Document 1 discloses a development device equipped with a plurality of regulating members that can regulate the height of the developer surface while the developer is being circulated and conveyed. According to Patent Document 1, the development device disclosed can appropriately regulate the developer surface, and the developer surface is stabilized. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-167450 A Summary of the Invention [Problem to be solved by the invention]

[0006] According to the developing device disclosed in the above-mentioned Patent Document 1, even if the toner is replenished as needed, the developer surface can be appropriately regulated and the developer surface can be stabilized. However, in a developing device configured to replenish toner as needed, the toner becomes lumpy when replenished, and even if the toner is stirred by the conveying screw, the lumps of toner move in a bouncy manner above the conveying screw, which prevents the developer from being sufficiently stirred. If the developer cannot be sufficiently stirred, the amount of charge on the toner is insufficient, resulting in poorly charged toner. If poorly charged toner occurs in this way, the quality of the image formed on the paper may be reduced.

[0007] The present disclosure has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a developing device that can sufficiently agitate developer and suppress the occurrence of poorly charged toner, and an image forming apparatus equipped with the same. [Means for solving the problem]

[0008] A developing device according to one aspect of the present disclosure includes a rotatable developer carrier, and a portion of the developer transported in a rotation axis direction of the developer carrier is supplied to the developer carrier. The developing device has a first chamber provided with a first transport member that transports the developer in one direction along the rotation axis direction, a second transport member that transports the developer in the other direction along the rotation axis direction, and a second chamber in which the developer carrier is provided above the second transport member. The first transport member includes a first rotating shaft and a first spiral blade provided on the first rotating shaft, and rotates to transport the developer in one direction along the rotation axis direction. the second transport member comprises a second rotating shaft and a spiral second blade provided on the second rotating shaft, and transports the developer in the other direction by rotating; the first chamber and the second chamber are connected at their respective ends to form a circulation path for the developer; an upper surface rib is formed on a ceiling portion of the first chamber so as to extend toward the first transport member, and the upper surface rib is arranged so as to intersect with the first rotating shaft at an angle greater than 0 degrees and less than 90 degrees in a plan view seen from the ceiling portion side.

[0009] In this way, since the upper surface ribs are provided, it is possible to prevent a phenomenon in which a part of the developer moves in a lump on the first blade (first transport member) when the developer is transported through the first chamber. This makes it possible to thoroughly stir the developer. Since the developer can be thoroughly stirred, it is possible to prevent the occurrence of poorly charged toner. It is possible to prevent image defects.

[0010] In the developing device described above, the upper surface rib may be arranged at least on a side where the developer is pushed upward as the first blade rotates in conjunction with rotation of the first rotating shaft.

[0011] This makes it possible to more reliably prevent a phenomenon in which a portion of the pushed-up developer moves in the form of a lump on the first blade (first transport member).

[0012] In the developing device described above, the upper surface rib may have a curved portion that is curved so as to fit along an outer periphery of the first blade.

[0013] As a result, the upper surface ribs are positioned along the outer circumference of the first blade, which more reliably prevents a portion of the developer pushed up by the rotation of the first blade from moving in clumps on the first blade (first transport member).

[0014] In addition, in the above-mentioned developing device, the curved portion of the upper surface rib may be formed on the side where the developer is pushed upward as the first blade rotates in conjunction with rotation of the first rotating shaft.

[0015] This makes it possible to more reliably prevent a phenomenon in which part of the developer pushed up by the rotation of the first blade moves in the form of a lump on the first blade (first transport member).

[0016] In addition, in the above-mentioned developing device, the end surface of the upper surface rib facing the first transport member may have a first inclined portion formed so as to move away from the first transport member toward the opposite side from the curved portion.

[0017] This makes it possible to smoothly transport the developer in the first chamber while preventing a phenomenon in which part of the developer moves in clumps on the first blade (first transport member).

[0018] In addition, in the above-mentioned developing device, the end portion of the upper surface rib opposite the curved portion may not be in contact with the side wall of the first chamber, and a space may be formed between the end portion and the side wall.

[0019] This prevents a portion of the developer from moving in clumps on the first blade (first transport member) when the developer is transported in the first chamber, while the space formed allows the developer to be transported smoothly.

[0020] In addition, in the above-mentioned developing device, a second inclined portion may be formed on the upstream side of the first chamber in the one direction at an end portion of the upper surface rib opposite the curved portion so as to become thinner toward the opposite side of the curved portion.

[0021] This prevents a portion of the developer from moving in clumps on the first blade (first transport member) when the developer is transported in the first chamber, while the formation of the second inclined portion enables the developer to be transported smoothly.

[0022] In addition, in the above-mentioned developing device, the upper surface rib may have a third inclined portion formed on the upstream side of the first chamber in the one direction so that the upper surface rib becomes thinner from the ceiling side toward the first conveying member.

[0023] This prevents a portion of the developer from moving in clumps on the first blade (first transport member) when the developer is transported in the first chamber, while the formation of the third inclined portion enables the developer to be transported smoothly.

[0024] In the developing device described above, a plurality of the upper surface ribs may be arranged along the axial direction of the developer carrier.

[0025] This makes it possible to more reliably prevent a phenomenon in which a portion of the developer moves in clump form on the first blade (first transport member) when the developer is transported through the first chamber.

[0026] An image forming apparatus according to an aspect of the present disclosure includes the developing device described above.

[0027] This allows the developer to be sufficiently agitated by the developing device, making it possible to prevent the occurrence of poorly charged toner and thus to prevent image defects.

[0028] In addition, the above-mentioned image forming apparatus may further include a container member that contains developer to be supplied to the developing device, and the developing device may include a developer supply section to which the developer is supplied from the container member.

[0029] In this way, even if a developing device to which developer is supplied is provided, the developing device can sufficiently stir the developer, thereby preventing the occurrence of poorly charged toner and image defects. Effect of the Invention

[0030] According to the present disclosure, it is possible to provide a developing device capable of sufficiently agitating a developer and suppressing the occurrence of poorly charged toner, and an image forming apparatus including the same. [Brief description of the drawings]

[0031] [Figure 1] 1 is a perspective front view showing a schematic configuration of an image forming apparatus having a developing device according to a first embodiment of the present disclosure. [Diagram 2] 1 is an exploded perspective view showing a schematic configuration of a developing device according to a first embodiment of the present disclosure. [Diagram 3] 1 is a schematic perspective view showing a portion of a developing device according to a first embodiment of the present disclosure. [Figure 4] 1 is a schematic cross-sectional view of a developing device according to a first embodiment of the present disclosure. [Diagram 5] FIG. 2 is a schematic plan view showing a first chamber and a second chamber of the developing device according to the first embodiment of the present disclosure. [Figure 6] FIG. 11 is a schematic perspective view showing a portion of a developing device according to a second embodiment of the present disclosure. [Figure 7] 6 is a schematic cross-sectional view of a developing device according to a second embodiment of the present disclosure. [Figure 8]11 is a schematic plan view showing a first chamber and a second chamber of a developing device according to a second embodiment of the present disclosure. FIG. [Figure 9] FIG. 11 is a schematic perspective view showing a portion of a developing device according to a third embodiment of the present disclosure. [Figure 10] FIG. 11 is a schematic cross-sectional view of a developing device according to a third embodiment of the present disclosure. [Figure 11] 13 is a schematic plan view showing a first chamber and a second chamber of a developing device according to a third embodiment of the present disclosure. FIG. [Figure 12] FIG. 11 is a schematic perspective view showing a portion of a developing device according to a fourth embodiment of the present disclosure. [Figure 13] FIG. 11 is a schematic cross-sectional view of a developing device according to a fourth embodiment of the present disclosure. [Figure 14] 13 is a schematic plan view showing a first chamber and a second chamber of a developing device according to a fourth embodiment of the present disclosure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described with reference to the drawings.

[0033] (First embodiment) An image forming apparatus having a developing device according to a first embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a perspective front view showing a schematic configuration of an image forming apparatus having a developing device according to a first embodiment of the present disclosure.

[0034] Here, in the coordinates described by arrows and symbols in the drawings from FIG. 1 to FIG. 14, the X direction is the left-right direction (horizontal direction) when the image forming apparatus 100 is viewed from the front. The direction indicated by the X direction arrow is the positive direction, which indicates the left side, and the direction opposite to the arrow is the negative direction, which indicates the right side. The Y direction is the depth direction (front-back direction) perpendicular to the X direction, and the positive direction of the Y direction arrow and the negative direction opposite to the Y direction arrow respectively indicate the front side, which is the operator side, and the back side, which is the opposite side to the operator side. The Z direction is the up-down direction, that is, the vertical direction, and the positive direction of the Z direction arrow and the negative direction opposite to the Z direction arrow respectively indicate the upper side and the lower side. Note that when the image forming apparatus 100 is not shown and only the components of the image forming apparatus 100 are illustrated, the coordinates are shown in a state in which the components are incorporated in the image forming apparatus 100.

[0035] The image forming apparatus 100 is a multifunction machine having a copy function, a scanner function, a facsimile function and a printer function, and includes an image reading device 102 and an image forming apparatus main body 101 .

[0036] The image reading device 102 includes an image reading unit 130 and a document feeder 160 (automatic document feeder (ADF)). The document feeder 160 is provided above the image reading unit 130 and is supported so as to be freely openable and closable relative to the image reading unit 130.

[0037] The document feeder 160 conveys one or more documents G placed on a document placement tray 161 one by one to a document reading position 130b. The image reader 102 captures an image of the document passing through the document reading position 130b with a document reading section 130d via a scanning optical section 130c, and reads the document. The document feeder 160 includes a document discharge tray 162 on which the document G that has passed through the document reading position 130b is stacked.

[0038] The image reading section 130 includes an original placement stage 130a on which an original G is placed, an optical scanning section 130c that reads the original, and an original reading section 130d.

[0039] When the document feeder 160 is opened, the document placement table 130a above the image reading unit 130 is opened, allowing the document G to be placed manually. When reading the document G placed on the document placement table 130a, the scanning optical unit 130c is moved in the X direction, and the document is imaged and read by the document reading unit 130d.

[0040] As described above, the image reading unit 130 scans the scanning optical unit 130c to read the document placed on the document placement table 130a, or reads the document G transported to the document reading position 120b by the document feeder 160, and generates image data.

[0041] The image forming apparatus main body 101 includes an image forming section 50, an exposure device 1, an intermediate transfer device 70, a developer container 8, a secondary transfer device 11, a fixing device 12, a sheet transport path S, a paper feed cassette 18, and a sheet discharge tray 141.

[0042] The image forming apparatus 100 handles image data corresponding to a color image using the colors black (K), cyan (C), magenta (M), and yellow (Y), or a monochrome image using a single color (e.g., black).

[0043] The image forming section 50 of the image forming apparatus 100 has four image stations Pa, Pb, Pc, Pd corresponding to the colors black, cyan, magenta, and yellow. Each of these image stations Pa, Pb, Pc, Pd includes a developing device 2, a photosensitive drum 3, a drum cleaning device 4, and a charging device 5, and four types of toner images are formed by these image stations Pa, Pb, Pc, Pd. That is, in the image forming apparatus 100, four developing devices 2, four photosensitive drums 3, four drum cleaning devices 4, and four charging devices 5 are provided, and each corresponds to black, cyan, magenta, and yellow. Here, the developer storage container 8 is provided to supply developer containing toner to the corresponding developing devices 2 of the four image stations Pa, Pb, Pc, Pd.

[0044] The photosensitive drum 3 has a photosensitive layer on its surface, which is conductive in the area exposed to light and insulating in the area not exposed to light. The charging device 5 charges the surface of the photosensitive drum 3 to a predetermined potential. The exposure device 1 exposes the surface of the photosensitive drum 3, which is charged to a predetermined potential, based on image data read by the document reading unit 130d or image data sent from an external device such as a PC, to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photosensitive drum 3 with toner, thereby forming a toner image on the surface of the photosensitive drum 3. The toner images formed on the surface of the photosensitive drum 3 are sequentially transferred to an intermediate transfer belt 71 by an intermediate transfer device 70, which will be described later. The transfer residual toner remaining on the surface of the photosensitive drum 3 without being transferred to the intermediate transfer belt 71 is removed and collected by the drum cleaning device 4. By repeating the series of operations described above, toner images of each color are formed on the surface of each photosensitive drum 3 one after another.

[0045] The intermediate transfer device 70 includes an intermediate transfer roller 6, an endless intermediate transfer belt 71, an intermediate transfer driving roller 72, an intermediate transfer driven roller 73, and a cleaning device 9. The intermediate transfer belt 71 is an endless belt that can rotate and is wound around the intermediate transfer driving roller 72 and the intermediate transfer driven roller 73. In other words, the intermediate transfer belt 71 is stretched around the intermediate transfer driving roller 72 and the intermediate transfer driven roller 73. Four intermediate transfer rollers 6 are provided inside the intermediate transfer belt 71 so as to form four types of toner images corresponding to the respective colors. The intermediate transfer rollers 6 bring the intermediate transfer belt 71 into contact with the corresponding photosensitive drums 3, and transfer the toner images of the respective colors formed on the surfaces of the photosensitive drums 3 to the intermediate transfer belt 71.

[0046] The image forming apparatus 100 sequentially transfers and superimposes the toner images of each color formed on the surface of each photosensitive drum 3, forming a color toner image on the surface of an intermediate transfer belt 71 stretched between an intermediate transfer driving roller 72 and an intermediate transfer driven roller 73. The toner images intermediately transferred onto the surface of the intermediate transfer belt 71 are transferred onto a sheet P by a secondary transfer device 11, which will be described later. Residual toner that has not been transferred to the sheet P and remains on the surface of the intermediate transfer belt 71 is removed from the surface of the intermediate transfer belt 71 and collected by a cleaning device 9.

[0047] The secondary transfer device 11 includes a secondary transfer roller 11a that is in contact with the intermediate transfer belt 71 and can rotate together with the intermediate transfer belt 71. The secondary transfer roller 11a pinches and conveys a sheet P conveyed through a sheet conveying path S in a transfer nip area TN, which is an abutment portion with the intermediate transfer belt 71. When the sheet P passes through the transfer nip area TN, the toner image on the surface of the intermediate transfer belt 71 is transferred to the sheet P, and the sheet P is conveyed to the fixing device 12.

[0048] The fixing device 12 includes a fixing roller 31 and a pressure roller 32 that rotate while sandwiching the sheet P. A heater, which is a heat source, is disposed inside the fixing roller 31, and the surface of the fixing roller 31 is heated to a predetermined temperature. Therefore, the toner image transferred onto the sheet P is fixed by the heat and pressure so as not to come off the sheet P when it is conveyed between the fixing roller 31 and the pressure roller 32.

[0049] The paper feed cassette 18 is a cassette for storing sheets P used for image formation (on which a toner image is formed), and is provided below the exposure device 1. The sheet P is pulled out from the paper feed cassette 18 by the pickup roller 16 and conveyed to the sheet conveying path S. The sheet P conveyed to the sheet conveying path S passes through the secondary transfer device 11 and the fixing device 12, is conveyed to the discharge roller 17, and is discharged to a sheet discharge tray 141 in the discharge section 140. The conveying roller 13, the registration roller 14, and the discharge roller 17 are arranged in the sheet conveying path S. The conveying roller 13 promotes the conveyance of the sheet P. The registration roller 14 temporarily stops the sheet P and aligns the leading edge of the sheet P. Furthermore, the registration roller 14 conveys the stopped sheet P in accordance with the timing of the color toner image on the intermediate transfer belt 71. As described above, the color toner image on the intermediate transfer belt 71 is transferred to the sheet P in the transfer nip area TN between the intermediate transfer belt 71 and the secondary transfer roller 11a.

[0050] In FIG. 1, the number of sheet feed cassettes 18 is one, but the present invention is not limited to this. A configuration may be provided in which a plurality of sheet feed cassettes 18 are provided to stack different types of sheets P, respectively.

[0051] Furthermore, when forming an image on the back side of the sheet P in addition to the front side, the image forming apparatus 100 switches back the sheet P on which the toner image has been fixed at the discharge rollers 17 and conveys it to a sheet inversion path Sr. The sheet P, which has been inverted by this switchback, is conveyed through the sheet inversion path Sr and is stopped when it reaches the registration rollers 14. Furthermore, the image forming apparatus 100 forms an image on the back side of the sheet P that has reached the registration rollers 14 and stopped there in the same manner as on the front side, and conveys it to the sheet discharge tray 141.

[0052] Next, the configuration of the developing device 2 will be described with reference to the drawings. Figure 2 is an exploded perspective view showing a schematic configuration of the developing device according to the first embodiment of the present disclosure.

[0053] As shown in FIG. 2, the developing device 2 includes the developing roller 21 that rotates around a rotation axis, the first transport member 22 and the second transport member 23 that are arranged parallel to the rotation axis of the developing roller 21, a main body 80, and an upper cover 81. An open section 86 to which the upper cover 81 is attached is provided on the upper side of the main body 80, and the developing roller 21, the first transport member 22, and the second transport member 23 are arranged in an internal space formed by attaching the upper cover 81 to the open section 86. The main body 80 includes a first chamber 84 and a second chamber 85 that extend in the direction of the rotation axis of the developing roller 21, and the first transport member 22 is rotatably supported in the first chamber 84, and the second transport member 23 and the developing roller 21 are rotatably supported in the second chamber 85. The upper portions of the first chamber 84 and the second chamber 85 are covered by attaching a cover member 81 to the main body 80. Here, the first chamber 84 and the second chamber 85 communicate with each other via a first communication portion 87 and a second communication portion 88 that communicate with each other on the front side and the back side in the Y direction, respectively, to form one circulation path. (The first communication portion 86 and the second communication portion 88 are formed by a first opening and a second opening provided in a partition wall 84b that separates the first chamber 84 and the second chamber 85.) The first chamber 84 and the second chamber 85 contain a developer containing toner to be supplied to the developing roller 21. In this disclosure, a two-component developer containing toner made of a nonmagnetic material and a carrier made of a magnetic material is used as the developer contained in the first chamber 84 and the second chamber 85, but a one-component developer consisting only of toner containing a magnetic material may be used.

[0054] Next, a first gear 29 is attached to the end of the first conveying member on the negative side in the Y direction, i.e., the end on the back side. A second gear 28 is provided on the end of the second conveying member on the negative side in the Y direction, i.e., the end on the back side. The second gear 28 has a coupling gear 28a and an intermediate gear 28b that meshes with the first gear 29. The coupling gear 28a meshes with a drive gear (not shown) that can be driven by a drive source (not shown) provided in the image forming apparatus 100 when the developing device 2 is attached to the image forming apparatus 100. In other words, when the developing device 2 is attached to the image forming apparatus 100 and the drive source provided in the image forming apparatus 100 is driven, the rotational force of the drive gear is transmitted in this order to the coupling gear 28a, the intermediate gear 28b, and the first gear 29, and the first conveying member 22 and the second conveying member 23 rotate. The second transport member 23 has a gear (not shown) at the end (front end) opposite to the end where the second gear 28 is attached, which transmits a rotational force to the developing roller 21, and is configured to transmit the rotational force via this gear to a gear (not shown) attached to the developing roller 21. In other words, when the second transport member rotates, the developing roller 21 also rotates simultaneously.

[0055] The first conveying member 22 and the second conveying member 23 have a first blade 26 and a second blade 27, which are spiral-shaped, respectively. When a rotational force from a drive source of the image forming apparatus 100 is transmitted to the first gear 29, the first conveying member 22 rotates, and the first blade 26 conveys the developer accommodated in the first accommodation chamber 21 to the front side in the Y direction, that is, in the positive direction (one direction). The developer conveyed to the front side end in the Y direction by the first conveying member 22 is conveyed to the second chamber 85 via the first communicating portion 87. Similarly, when the second conveying member 23 rotates, the second blade 27 conveys the developer conveyed to the second chamber 85 to the rear side in the Y direction, that is, in the negative direction (the other direction). The developer conveyed to the rear side end in the Y direction by the second conveying member 23 is conveyed to the first chamber 84 via the second communicating portion 88. As described above, the developing device 2 is configured such that when the first transport member 22 and the second transport member 23 rotate, the developer circulates between the first chamber 84 and the second chamber 85. Although not shown, the developing roller 21 is a magnet roller having a rotating sleeve made of a non-magnetic material and non-rotating magnets fixed in order on the inside so that the polarities are different in the circumferential direction. Therefore, a part of the developer sent to the back side in the Y direction by the second transport member 23 is attracted by the magnetic force generated by the magnet in the developing roller 21 and supplied to the surface of the developing roller 21. A developing bias, which is a predetermined voltage, is supplied to the developing roller 21 from a power source not shown. Then, a developing electric field formed between the developing roller 21 and the photosensitive drum 3 (see FIG. 1) supplies non-magnetic toner contained in the two-component developer (developer) to an electrostatic latent image formed on the surface of the photosensitive drum 3, thereby visualizing the electrostatic latent image. That is, a toner image is formed on the photosensitive drum 3.

[0056] As described above, the developing device 2 includes the rotatable developing roller 21, and a portion of the developer transported in the direction of the rotation axis of the developing roller 21 is supplied.

[0057] When a toner image is formed on the photosensitive drum 3 as described above, that is, when development is performed, the toner on the developing roller 21 is consumed, and the consumed toner is again supplied from the developer transported by the second transport member 23. Therefore, the amount of toner in the developer transported through the first chamber 84 and the second chamber 85 decreases. Here, the first chamber 84 is provided with a toner sensor (not shown) for detecting the toner content (amount) in the developer, and when the toner content (amount) in the developer becomes equal to or lower than a predetermined value in response to a signal from the toner sensor, a supply device (not shown) provided in the image forming apparatus 100 is driven, and the developer containing the toner contained in the developer container 8 is supplied to the first chamber 84 through a developer supply unit 83 provided near the end of the first chamber 84 on the negative side in the Y direction, that is, the rear side end. The position where the developer supply unit 83 is provided is near the end of the first chamber 84 on the Y direction side, which corresponds to the upstream side of the transport direction (one direction) of the developer in the first chamber 84.

[0058] Next, a detailed configuration of the developing device 2 will be described with reference to the drawings. Fig. 3 is a schematic perspective view showing a part of the developing device according to the first embodiment of the present disclosure. Fig. 4 is a schematic cross-sectional view of the developing device according to the first embodiment of the present disclosure. Fig. 5 is a schematic plan view showing the first and second chambers of the developing device according to the first embodiment of the present disclosure.

[0059] Here, Fig. 3 is a perspective view of the developing device 2 with the upper cover 81 removed, as viewed from the rear side. Fig. 4 is a cross-sectional view of the developing device 2 as viewed from the rear side. Fig. 5 is a plan view of the first chamber 84 and the second chamber 85 as viewed from the top side, and also shows the top surface rib 82.

[0060] As shown in FIGS. 3 to 5, the first transport member 22 is installed in the first chamber 84 and has a first rotating shaft 24, and a first blade 26 having a spiral shape is formed around the first rotating shaft 24. As described above, the first transport member 22 is disposed in the first chamber 84 so as to be parallel to the rotating shaft of the developing roller 21, and the first rotating shaft 24 and the first chamber 84 are formed so as to extend parallel to the rotating shaft of the developing roller 21, that is, in the Y direction. When the first transport member 22 rotates around the first rotating shaft 24, the developer accommodated in the first chamber 84 is transported in the positive direction (one direction) of the Y direction by the first blade 26. Specifically, the first transport member 22 rotates in the rotation direction R1, so that the developer is transported in the front direction of the Y direction.

[0061] Further, the second transport member 23 is installed in the second chamber 85, has a second rotation shaft 25, and has a spiral second blade 27 formed around the second rotation shaft 25. As described above, the second transport member 23 is also disposed in the second chamber 85 so as to be parallel to the rotation shaft of the developing roller 21, and the second rotation shaft 25 and the second chamber 85 are formed so as to be parallel to the rotation shaft of the developing roller 21, that is, to extend in the Y direction.

[0062] When the second transport member 23 rotates about the second rotation shaft 25, the developer accommodated in the second chamber 85 is transported in the negative direction (other direction) of the Y direction by the second blade 27. Specifically, the second transport member 23 rotates in the rotation direction R2, whereby the developer is transported in the front direction of the Y direction.

[0063] As described above, the first chamber 84 is provided with the first transport member 22 that transports the developer in one direction along the rotational axis direction of the developing roller 21, and the second chamber 85 is provided with the second transport member 23 that transports the developer in the other direction along the rotational axis direction of the developing roller 21, and the developing roller 21 above (on the upper side of) the second transport member 23. The first transport member 22 is provided with a first rotating shaft 24 and a spiral first blade 26 provided on the outer circumferential surface of the first rotating shaft 24 in order to transport the developer in one direction, and the second transport member 23 is provided with a second rotating shaft 25 and a spiral second blade 27 provided on the outer circumferential surface of the second rotating shaft 25 in order to transport the developer in the other direction.

[0064] In the developing device 2 according to the first embodiment, the first transport member 22 and the second transport member 23 rotate in opposite directions, but this is due to the mechanism of the developing device 2, and the first transport member 22 and the second transport member 23 may rotate in the same direction. However, even in this case, the developer transport directions by the first transport member 22 and the second transport member 23 should be opposite to each other, and a developer circulation path should be formed by the first chamber 84 and the second chamber 85.

[0065] As shown in Fig. 4, in the upper cover 81, a ceiling portion 81a constituting the upper wall of the first chamber 84, i.e., the ceiling portion 81a of the first chamber, is formed with an upper surface rib 82 extending downward (toward the lower side in the Z direction) toward the first conveying member 22. It is preferable that the lower end (the end portion on the lower side in the Z direction) of the upper surface rib 82 is close to the first conveying member 22. In particular, a curved portion 82a is formed on the end side on the left side (the side opposite the second chamber 85, the positive side in the X direction) of the upper surface rib 82 in Fig. 4. The curved portion 82a is curved so as to follow the outer periphery of the first blade 26, and is formed close to the first blade 26 so as to form a predetermined gap between it and the first blade 26.

[0066] Here, the curved portion 82a of the upper surface rib 82 is provided on the opposite side to the second chamber 85, and this is related to the fact that the first blade 26 is formed to move clockwise as it moves toward the front side, which is the positive direction of the Y direction. (See FIG. 3) When the first transport member 22 rotates in the rotation direction R1 (counterclockwise), the first blade 26 also rotates in the rotation direction R1, and at this time, among the developer contained in the first chamber 84, the developer present on the opposite side of the first rotating shaft 24 from the second chamber 85 is pushed (lifted) from the bottom side to the top side by the first blade 26 and transported to the front side, which is the positive direction side of the Y direction. In other words, the developer located on the left side (opposite the second chamber 85), which is the positive direction side of the first rotating shaft 24 in the X direction in FIG. 4, is pushed up by the rotation of the first transport member 22 and transported toward the front side. On the other hand, among the developer contained in the first chamber 84, the developer present on the second chamber 85 side of the first rotating shaft 24 is pushed down from the upper side by the rotation of the first blade 22 and transported to the front side, which is the positive side in the X direction. That is, the developer located on the right side (second chamber 85 side) of the first rotating shaft 24 in the X direction in FIG. 4 is pushed down and transported to the front side by the rotation of the first transport member 22. Therefore, the free surface of the developer contained in the first chamber 84 is not horizontal while the first transport member 22 is rotating, and is higher on the left side of the first rotating shaft 24 than on the right side. In particular, when the amount of developer in the first chamber 84 is large, the free surface of the developer present on the left side of the first rotating shaft 24 may be higher than the first blade 26. The transport force of the first blade 26 does not act on such developer located higher than the first blade 26, but it may ride on the flow of the developer transported by the first blade 26 located below and move near the free surface to the front side, which is the front direction in the Y direction, and be sent to the second chamber 85 and supplied to the developing roller 21. The toner that moves near the free surface of the developer in this way and is supplied to the developing roller 21 is not sufficiently agitated by the first blade 22, so that the frictional charging with the carrier is insufficient and the charge amount is low, which may cause fogging (image defect in which toner is supplied to non-image areas).

[0067] In the developing device 2 in the first embodiment, the upper surface rib 82 is provided above (on the upper side of) the first blade 26 so as to be close to the first blade 26. Therefore, even if the amount of developer contained in the first chamber 84 increases and the free surface is located above (on the upper side) the first conveying member 22, the developer pushed upward by the rotation of the first conveying member 22 is blocked by the upper surface rib 82 and moved to an area in the first chamber 84 where the free surface is lower on the side pushed downward by the rotation of the first conveying member 22. This improves the stirring effect of the developer, and the toner and carrier are sufficiently stirred, so that the occurrence of poorly charged toner can be suppressed. Therefore, problems such as unevenness in the toner image formed on the photosensitive drum 3 are suppressed, and the formed image is less likely to have image defects.

[0068] As described above, when the toner (developer containing toner) is supplied from the developer supply unit 83 and mixed into the developer in the first chamber 84 and the second chamber 85 and circulates in the first chamber 84 and the second chamber 85, the toner supplied via the developer supply unit 83 contains toner that has aggregated and become clumped. If the free surface of the developer in the first chamber 84 is above the first conveying member 22, the clumped toner may not be scraped in by the first blade 26 and may move in the conveying direction in a bouncing manner above the first blade 26. If this phenomenon occurs, the clumped toner may be supplied to the developing roller 21 and developed in clump form, which may cause image defects. However, as described above, in the first embodiment, the upper surface rib 82 is provided, so that the clumped toner can be effectively prevented from bouncing and moving near the free surface of the developer above the first blade 26. Furthermore, since the toner (developer) is drawn into the first blade 26 and thoroughly stirred, the developer is thoroughly stirred and the occurrence of poorly charged toner can be suppressed, preventing the occurrence of defective images.

[0069] 4 (the opposite side to the second chamber 85), it is possible to more effectively prevent clumps of toner from bouncing above the first blade 26. In other words, the curved portion 82a is formed on the side of the top rib 82 where the developer contained in the first chamber 84 is pushed upward as the first blade 26 rotates in conjunction with the rotation of the first rotating shaft 24.

[0070] 5, the upper surface ribs 82 are arranged to be inclined with respect to the first rotation shaft 24 along the developer transport direction in a plan view seen from above, which is the ceiling portion 81a side. Specifically, the upper surface ribs 82 are arranged to intersect with the first rotation shaft 24 at an angle θ greater than 0 degrees and smaller than 90 degrees in a plan view seen from the ceiling portion side. This allows the developer pushed upward by the rotation of the first transport member 22 to be blocked by the upper surface ribs 82 and more effectively moved to a region in the first chamber 84 where the free surface is lower and is the side pushed downward by the rotation of the first transport member 22, thereby improving the agitation of the developer.

[0071] In addition, in a plan view of the ceiling portion 81a seen from above, it is preferable that the angle α between the first blade 26 and the upper surface rib 82 is close to perpendicular, and it is preferable that the angle α does not approach 0 degrees. In other words, it is preferable that the angle between the (surface of) the spiral first blade 26 and the (surface of) the upper surface rib 82 does not approach parallelism.

[0072] If the position of the ceiling portion 81a were to be made closer to the first blade 26 instead of providing the top surface rib 82, when toner is supplied from the developer supply portion 83, a temporary increase in the amount of developer could cause the developer to have nowhere to go, which could result in an impediment to transport. To avoid such problems, it is preferable to provide multiple top surface ribs 82 at a predetermined distance from each other along the Y direction. When providing multiple top surface ribs 82, it is preferable to arrange them at the pitch of the first blade 26, but the above effect can be obtained by providing just one.

[0073] Second embodiment A second embodiment of the present disclosure will be described below. The second embodiment differs from the first embodiment in that it includes a first conveying member 122 and an upper surface rib 182 that are different in configuration from the first conveying member 22 and the upper surface rib 82 in the first embodiment, but is otherwise similar to the first embodiment. Therefore, hereinafter, these differences will be described, and descriptions of other configurations will be omitted. Note that the same members as those in the first embodiment are given the same reference numerals.

[0074] The developing device 2 according to the second embodiment will be described with reference to the drawings. Fig. 6 is a schematic perspective view showing a part of the developing device according to the second embodiment of the present disclosure. Fig. 7 is a schematic cross-sectional view of the developing device according to the second embodiment of the present disclosure. Fig. 8 is a schematic plan view showing the first and second chambers of the developing device according to the second embodiment of the present disclosure.

[0075] Here, Fig. 6 is a perspective view of the developing device 2 with the upper cover 81 removed, as viewed from the rear side. Fig. 7 is a cross-sectional view of the developing device 2 as viewed from the rear side. Fig. 8 is a plan view of the first chamber 84 and the second chamber 85 as viewed from above, and also shows the upper surface rib 182.

[0076] As shown in FIGS. 6 to 8, the first transport member 122 is installed in the first chamber 84 and has a first rotating shaft 124, around which a first spiral blade 126 is formed. With this configuration, when the first transport member 122 rotates about the first rotating shaft 124 along the Y direction, the developer in the first chamber 84 is transported by the first blade 126. In addition, in the first chamber 84, the developer is transported in the positive direction of the Y axis. Specifically, the first transport member 122 rotates in the rotation direction R11, whereby the developer is transported in the positive direction of the Y direction.

[0077] Here, in the developing device 2 according to the second embodiment, the rotation direction R11 which is the rotation direction of the first transport member 122 is the same as the rotation direction R2 which is the rotation direction of the second transport member 23. However, the developer transport directions by the first transport member 122 and the second transport member 23 are opposite to each other, and the first chamber 84 and the second chamber 85 form a circulation path for the developer. Therefore, in the first transport member 122, the inclination of the first blade 126 with respect to the first rotating shaft 124 is configured to be inclined in the opposite direction to the inclination of the second blade 27 with respect to the second rotating shaft 25 with respect to the second transport member 23 (see FIG. 8).

[0078] As shown in Fig. 7, the upper cover 81 has a ceiling portion 81a that constitutes the upper wall of the first chamber 84, and the upper rib 182 is provided so as to extend downward (toward the lower side in the Z direction). That is, the upper rib 182 is provided so as to extend from the ceiling portion 81a toward the first conveying member 122. It is preferable that the lower end (the end portion on the lower side in the Z direction) of the upper rib 182 is close to the first conveying member 122. In particular, a curved portion 182a is formed on the right side (the second chamber 85 side, the negative direction side in the X direction) of the upper rib 182 in Fig. 7. The curved portion 182a is curved so as to follow the outer periphery of the first blade 126, and is formed close to the first blade 126 so as to form a predetermined gap between the first blade 126 and the curved portion 182a.

[0079] Here, the curved portion 182a of the upper surface rib 182 is provided on the same side as the second chamber 85, but this is related to the fact that the first blade 126 is formed to move counterclockwise as it moves toward the front side, which is the positive direction of the Y direction (see FIG. 6). When the first transport member 122 rotates in the rotation direction R11 (clockwise), the first blade 126 also rotates in the rotation direction R11, and at this time, the developer contained in the first chamber 84 that is on the same side as the second chamber 85 of the first rotating shaft 124 is pushed (lifted) from the bottom side to the top side by the first blade 126 and transported to the front side, which is the positive direction side of the Y direction. In other words, the developer located on the right side (the same side as the second chamber 85), which is the negative direction side of the X direction of the first rotating shaft 124 in FIG. 6, is pushed up and transported toward the front side by the rotation of the first transport member 122. On the other hand, among the developer contained in the first chamber 84, the developer present on the opposite side of the first rotating shaft 124 from the second chamber 85 is pushed down from the upper side by the rotation of the first blade 122 and transported to the front side, which is the positive side in the X direction. That is, the developer located on the left side of the first rotating shaft 124 in the X direction (opposite the second chamber 85) in FIG. 6 is pushed down and transported to the front side by the rotation of the first transport member 122. Therefore, the free surface of the developer contained in the first chamber 84 is not horizontal while the first transport member 22 is rotating, and is higher on the right side of the first rotating shaft 124 than on the left side. In particular, when the amount of developer in the first chamber 84 is large, the free surface of the developer present on the right side of the first rotating shaft 124 may be higher than the first blade 126. The transport force of the first blade 126 does not act on such developer located higher than the first blade 126, but it may ride on the flow of the developer transported by the first blade 126 located below and move near the free surface to the front side, which is the front direction in the Y direction, and be sent to the second chamber 85 and supplied to the developing roller 21. The toner that moves near the free surface of the developer in this way and is supplied to the developing roller 21 is not sufficiently stirred by the first blade 122, so that the frictional charging with the carrier is insufficient and the charge amount is low, which may cause fogging (image defect in which toner is supplied to a non-image area).

[0080] In the developing device 2 in the second embodiment, the upper surface rib 182 is provided above (on the upper side) the first blade 126 so as to be close to the first blade 126. Therefore, even if the amount of developer contained in the first chamber 84 increases and the free surface is located above (on the upper side) the first conveying member 122, the developer pushed upward by the rotation of the first conveying member 22 is blocked by the upper surface rib 182 and can be moved to a region in the first chamber 84 where the free surface is lower on the side pushed downward by the rotation of the first conveying member 122. This improves the stirring effect of the developer, and the toner and carrier are sufficiently stirred, so that the occurrence of poorly charged toner can be suppressed. Therefore, the occurrence of problems such as unevenness in the toner image formed on the photosensitive drum 3 can be suppressed, and the occurrence of image defects in the formed image can be suppressed. Therefore, the occurrence of problems such as unevenness in the toner image formed on the photosensitive drum 3 can be suppressed, and the occurrence of image defects in the formed image can be suppressed. This effect is the same as that of the first embodiment.

[0081] Furthermore, since the upper surface ribs 182 are provided, it is possible to effectively prevent clumps of toner from bouncing and moving near the free surface of the developer on the upper side of the first blade 126. Furthermore, since the toner (developer) is scraped into the first blade 126 and thoroughly agitated, the developer is sufficiently agitated to suppress the occurrence of poorly charged toner, and the occurrence of poor images is prevented.

[0082] As described above, when the toner (developer containing toner) is supplied from the developer supply unit 83 and mixed into the developer in the first chamber 84 and the second chamber 85 and circulates in the first chamber 84 and the second chamber 85, the toner supplied via the developer supply unit 83 contains toner that has aggregated and become clumped. If the free surface of the developer in the first chamber 84 is above the first conveying member 122, the clumped toner may not be scraped in by the first blade 126 and may move in the conveying direction in a bouncing manner above the first blade 126. If this phenomenon occurs, the clumped toner may be supplied to the developing roller 21 and developed in clump form, which may cause image defects. However, as described above, even in the second embodiment, the upper surface rib 182 is provided, so that the clumped toner can be effectively prevented from bouncing and moving near the free surface of the developer above the first blade 126. Furthermore, since the toner (developer) is drawn into the first blade 126 and thoroughly stirred, the developer is thoroughly stirred and the occurrence of poorly charged toner can be suppressed, preventing the occurrence of defective images.

[0083] Furthermore, by forming a curved portion 182a close to and along the first blade 126 on the right side (the same side as the second chamber 85) of the upper surface rib 182 in Figure 7, clumps of toner can be more effectively prevented from bouncing above the first blade 126.

[0084] 8, the upper surface rib 182 is disposed at an angle with respect to the first rotation shaft 124 along the developer transport direction in a plan view seen from above on the ceiling portion 81a side. Specifically, the upper surface rib 182 and the first rotation shaft 124 intersect at an angle θ1, which is greater than 0 degrees and smaller than 90 degrees. This allows the developer pushed upward by the rotation of the first transport member 122 to be blocked by the upper surface rib 182 and to be more effectively moved to a region in the first chamber 84 where the free surface is lower and where the developer is pushed downward by the rotation of the first transport member 122, thereby improving the agitation of the developer.

[0085] In addition, in a plan view of the ceiling portion 81a seen from above, it is preferable that the angle α1 between the first blade 126 and the upper surface rib 182 is close to perpendicular, and it is preferable that the angle α1 does not approach 0 degrees. In other words, it is preferable that the angle between the (surface of) the spiral first blade 126 and the (surface of) the upper surface rib 182 does not approach parallel.

[0086] Third embodiment A third embodiment of the present disclosure will be described below. The third embodiment differs from the first embodiment in that, instead of the top rib 82 in the first embodiment, a top rib 282 having a different configuration is provided, but otherwise the third embodiment is similar to the first embodiment. Therefore, the following will describe this difference, and will omit a description of the other configurations. The same reference numerals are used for the same members as in the first embodiment.

[0087] The developing device 2 according to the third embodiment will be described with reference to the drawings. Fig. 9 is a schematic perspective view showing a part of the developing device according to the third embodiment of the present disclosure. Fig. 10 is a schematic cross-sectional view of the developing device according to the third embodiment of the present disclosure. Fig. 11 is a schematic plan view showing the first and second chambers of the developing device according to the third embodiment of the present disclosure.

[0088] Here, Fig. 9 is a perspective view of the developing device 2 with the upper cover 81 removed, as viewed from the rear side. Fig. 10 is a cross-sectional view of the developing device 2 as viewed from the rear side. Fig. 11 is a plan view of the first chamber 84 and the second chamber 85 as viewed from above, and also shows the upper surface rib 282.

[0089] 9 to 11, an upper surface rib 282 is provided on the ceiling portion 81a of the upper cover 81 located above the first chamber 84 so as to extend downward. In other words, the upper surface rib 282 is provided so as to face from the ceiling portion 81a toward the first conveying member 22. It is preferable that the lower end of the upper surface rib 282 is close to the first conveying member 22. In particular, a curved portion 282a is formed on the left side (opposite side to the second chamber 85) of the upper surface rib 282 in FIG. 10, and the curved portion 282a is curved so as to follow the outer periphery of the first blade 26 and is formed close to the first blade 26.

[0090] Here, the curved portion 282a of the upper surface rib 282 is provided on the opposite side to the second chamber 85, and this is related to the fact that the first blade 26 is formed to move clockwise as it moves toward the front side, which is the positive direction of the Y direction (see FIG. 9). When the first transport member 22 rotates in the rotation direction R1 (counterclockwise), the first blade 26 also rotates in the rotation direction R1, and at this time, the developer contained in the first chamber 84 and present on the opposite side of the first rotating shaft 24 to the second chamber 85 is pushed (lifted) from the bottom side to the top side by the first blade 26 and transported to the front side, which is the positive direction side of the Y direction. In other words, the developer located on the left side (opposite the second chamber 85), which is the positive direction side of the first rotating shaft 24 in the X direction in FIG. 10, is pushed up by the rotation of the first transport member 22 and transported toward the front side. On the other hand, of the developer contained in the first chamber 84, the developer present on the second chamber 85 side of the first rotating shaft 24 is conveyed to the front side, which is the positive side in the X direction, while being pushed down from the upper side by the rotation of the first blade 22. That is, the developer located on the right side in the X direction of the first rotating shaft 24 in FIG. 10 (the second chamber 85 side) is conveyed to the front side while being pushed down by the rotation of the first conveying member 22. Therefore, the free surface of the developer contained in the first chamber 84 is not horizontal while the first conveying member 22 is rotating, and is higher on the left side of the first rotating shaft 24 than on the right side.

[0091] Also, the top surface rib 282 is not formed on the ceiling portion 81a on the right side (second chamber 85 side) of the top surface rib 282 in FIG. 10. That is, the end surface of the top surface rib 282 on the second chamber 85 side is not in contact with the partition wall 84b of the first chamber 84, and a space 84a is formed between the top surface rib 282 and the partition wall 84b of the first chamber 84. However, the range where the space 84a is formed is a place where the developer is pushed down by the first blade 26, so the developer guided by the top surface rib 282 is reliably pushed down by the rotation of the first transport member 22 and transported to the front side in the Y direction while being stirred. This improves the stirring effect of the developer, and the toner and carrier are sufficiently stirred, so that the occurrence of poorly charged toner can be suppressed. As described above, the top surface rib 282 is arranged on the ceiling portion on the side where the developer contained in the first chamber 84 is pushed up by the rotation of the first blade 26 accompanying the rotation of at least the first rotating shaft 24.

[0092] Furthermore, a first inclined portion 91 is formed at the lower end of the upper surface rib 282 (the end surface facing the first conveying member 22) so as to move away from the first blade 26 (first conveying member 22) toward the second chamber 85 (toward the opposite side from the curved portion 282a). The first inclined portion 91 is formed at the lower end of the upper surface rib 282 so as to be inclined at an angle β with respect to the horizontal plane (XY plane) (see FIG. 10).

[0093] Further, a second inclined portion 92 is formed at the end of the upper surface rib 282 on the second chamber 85 side (see FIG. 11). The second inclined portion 92 is formed so that the upper surface rib 282 becomes thinner toward the second chamber 85 side (toward the opposite side from the curved portion 282a) in a plan view when the ceiling portion 81a is viewed from above. Further, the second inclined portion 92 is formed in the upper surface rib 282 so that the surface on the upstream side in the developer transport direction in the first chamber 84 is inclined, and the second inclined portion 92 is inclined at an angle γ.

[0094] By forming these first inclined portion 91 and second inclined portion 92, the developer located on the left side (opposite the second chamber 85) of the first rotating shaft 24, which is pushed upward by the rotation of the first conveying member 22, can be reliably guided to the right side (the same side as the second chamber 85) of the first rotating shaft 24, which has a lower free surface, and can be conveyed to the front side without impairing the stirring ability of the developer.

[0095] As described above, since the upper surface rib 282 is provided above the first blade 26 so as to be close to the first blade 26, the developer stirring effect is improved and the toner and carrier are sufficiently stirred. Furthermore, since the space 84a is formed and the upper surface rib 282 has the first inclined portion 91 and the second inclined portion 92, the developer is smoothly transported even when the upper surface rib 282 is provided. This makes it possible to suppress the occurrence of poorly charged toner, and suppresses problems such as unevenness in the toner image formed on the photosensitive drum 3, making it difficult for image defects to occur in the formed image.

[0096] (Fourth embodiment) A fourth embodiment of the present disclosure will be described below. Note that the fourth embodiment differs from the first embodiment in that, instead of the top rib 82 in the first embodiment, a top rib 382 having a different configuration is provided, but otherwise the fourth embodiment is similar to the first embodiment. Therefore, the following will describe this difference, and will omit a description of the other configurations. Note that the same reference numerals are used for the same members as in the first embodiment.

[0097] The developing device 2 according to the fourth embodiment will be described with reference to the drawings. Fig. 12 is a schematic perspective view showing a part of the developing device according to the fourth embodiment of the present disclosure. Fig. 13 is a schematic cross-sectional view of the developing device according to the fourth embodiment of the present disclosure. Fig. 14 is a schematic plan view showing the first and second chambers of the developing device according to the fourth embodiment of the present disclosure.

[0098] Here, Fig. 12 is a perspective view of the developing device 2 with the upper cover 81 removed, as viewed from the rear side. Fig. 13 is a cross-sectional view of the developing device 2 as viewed from the rear side. Fig. 14 is a plan view of the first chamber 84 and the second chamber 85 as viewed from above, and also shows the upper surface rib 382.

[0099] As shown in Figs. 12 to 14, in the upper cover 81, a top rib 382 is provided on the ceiling portion 81a constituting the upper wall of the first chamber 84 so as to extend downward. In other words, the top rib 282 is provided so as to face from the ceiling portion 81a toward the first conveying member 22. It is preferable that the lower end of the top rib 282 is close to the first conveying member 22. In particular, a curved portion 382a is formed on the left side (the opposite side to the second chamber 85) of the top rib 382 in Fig. 13. The curved portion 382a is curved so as to follow the outer periphery of the first blade 26, and is formed close to the first blade 26 so as to form a predetermined gap between the first blade 26 and the curved portion 382a.

[0100] 12, the upper surface rib 382 has a third inclined portion 93 formed so that the surface on the upstream side in the developer transport direction in the first chamber 84 is inclined. Specifically, the third inclined portion 93 is inclined at an angle δ so that the thickness of the upper surface rib 382 becomes thinner from the ceiling portion 81a toward the first transport member 22 (see FIG. 12). The formation of the third inclined portion 93 allows the first transport member 22 to transport the developer smoothly.

[0101] In this way, since the upper surface rib 382 is provided above the first blade 26 so as to be close to the first blade 26, the developer stirring effect is improved and the toner and carrier are sufficiently stirred. Furthermore, since the upper surface rib 382 has the third inclined portion 93, the developer is transported smoothly even when the upper surface rib 382 is provided. This makes it possible to suppress the occurrence of poorly charged toner, suppressing problems such as unevenness in the toner image formed on the photosensitive drum 3, and making it difficult for image defects to occur in the formed image.

[0102] The present disclosure is not limited to the above-described embodiments, and can be implemented in various other forms. Therefore, the embodiments are merely illustrative in all respects and should not be interpreted as being limited. The scope of the present disclosure is indicated by the claims, and is not limited in any way by the text of the specification. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present disclosure. [Explanation of symbols]

[0103] 1 Exposure equipment 2. Developing device 3 Photoconductor drum 4 Drum cleaning device 5. Charging device 6 Intermediate transfer roller 8 Developer container 9 Cleaning Equipment 11 Secondary transfer device 11a Secondary transfer roller 12 Fixing device 13 Conveyor roller 14 Registration roller 16 Pickup roller 17 Discharge roller 18 Paper feed cassette 21 Developing roller 22, 122 First conveying member 23 Second conveying member 24, 124 First rotating axis 25 Second Rotation Axis 26, 126 1st feather 27 Second Feather 28 2nd Gear 28a Coupling gear 28b Relay gear 29 1st Gear 31 Fuser roller 32 Pressure roller 50 Image forming section 70 Intermediate transfer device 71 Intermediate transfer belt 72 Intermediate transfer drive roller 73 Intermediate transfer driven roller 80 Main unit 81 Top cover 81a Ceiling 82, 182, 282, 382 Top rib 82a, 182a, 282a, 382a Curved section 83 Developer supply unit 84 Room 1 84a Space 84b Partition wall 85 Room 2 86 Open area 87 1st communication part (1st opening) 88 Second communication part (second opening) 91 1st slope part 92 2nd slope part 93 Third slope 100 Image forming device 101 Image forming apparatus main body 102 Image reading device 130 Image reading unit 130a Document stand 130b Document reading position 130c Scanning optical unit 130d Document reading section 140 Discharge section 141 Sheet output tray 160 Document feeder 161 Document tray 162 Document output tray G Manuscript P-sheet Pa, Pb, Pc, Pd Imaging Station R1, R2, R11 Rotation direction Sr sheet inversion pathway S Sheet transport path TN Transfer nip area θ, θ1, α, α1, β, γ, δ angle

Claims

1. A developing device including a rotatable developer carrier, the developer carrier being supplied with a portion of a developer transported in a direction of a rotation axis of the developer carrier, the developing device comprising: a first chamber including a first transport member configured to transport the developer in one direction along the rotation axis; a second transport member configured to transport the developer in another direction along the rotation axis direction, and a second chamber in which the developer carrier is provided above the second transport member, the first transport member includes a first rotating shaft and a first spiral blade provided on the first rotating shaft, and transports the developer in the one direction by rotating; the second conveying member includes a second rotating shaft and a second spiral blade provided on the second rotating shaft, and conveys the developer in the other direction by rotating; the first chamber and the second chamber are connected to each other at their respective ends to form a circulation path for the developer; A top surface rib is formed on the ceiling of the first chamber so as to extend toward the first conveying member, the upper surface rib is arranged so as to intersect with the first rotation shaft at an angle greater than 0 degrees and smaller than 90 degrees in a plan view seen from the ceiling side.

2. 2. The developing device according to claim 1, A developing device, characterized in that the upper surface rib is arranged at least on a side where the developer is pushed upward as the first blade rotates in conjunction with the rotation of the first rotating shaft.

3. 2. The developing device according to claim 1, the upper surface rib has a curved portion that is curved to fit along an outer periphery of the first blade.

4. 4. The developing device according to claim 3, A developing device characterized in that the curved portion of the upper surface rib is formed on a side where the developer is pushed upward as the first blade rotates in conjunction with the rotation of the first rotating shaft.

5. 5. The developing device according to claim 4, A developing device characterized in that an end surface of the upper surface rib facing the first transport member has a first inclined portion formed so as to move away from the first transport member toward the opposite side from the curved portion.

6. 5. The developing device according to claim 4, a developing device characterized in that an end portion of the upper surface rib opposite to the curved portion is not in contact with a side wall of the first chamber, and a space is formed between the end portion and the side wall.

7. 7. The developing device according to claim 6, a developing device characterized in that a second inclined portion is formed on the upstream side of the first chamber in the one direction at an end portion of the upper surface rib opposite the curved portion, the end portion becoming thinner toward the opposite side of the curved portion.

8. 2. The developing device according to claim 1, a third inclined portion is formed on the upstream side of the first chamber in the one direction so that the upper surface rib becomes thinner from the ceiling portion side toward the first transport member.

9. 2. The developing device according to claim 1, a developing device comprising: a developing member having a developer carrier and a developer holding member;

10. 10. An image forming apparatus comprising the developing device according to claim 1.

11. 11. The image forming apparatus according to claim 10, a developer container for containing a developer to be supplied to the developing device, The image forming apparatus according to claim 1, wherein the developing device includes a developer supplying section to which the developer is supplied from the container.

Images