Image forming apparatus

Abstract

To provide an image forming apparatus comprising a developing device that can prevent toner or the like from leaking from the inside of the developing device.SOLUTION: An image forming apparatus 100 comprises a developing device 2. The developing device 2 has a developer tank 26 that stores developer, a developing roller 21 that is installed near an opening 29 of the developer tank 26, and a seal member 23 that is installed near a position where the opening 29 and the developing roller 21 are in proximity to each other. When the developing roller 21 does not carry the developer, the seal member 23 is not in contact with the developing roller 21. When the developing roller 21 carries the developer, the seal member 23 is in contact with the developing roller 21 at a peak 27b of a mountain-like part 27a formed by the developer, or on the downstream side, in the direction of rotation F1 of the developing roller 21, of the peak 27b of the mountain-like part 27a.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an image forming apparatus including a developing device. [Background technology]

[0002] 2. Description of the Related Art In image forming apparatuses such as copiers, facsimile machines, printers, and multifunction machines, a toner image is formed on a photoconductor drum by a developing device, and this toner image is then transferred and fixed onto paper, thereby forming an image on the paper.

[0003] Generally, a developing device includes a developing tank that contains a two-component developer containing toner and a non-magnetic carrier, and a developing roller that carries the developer pumped up from the developing tank, and uses the developer carried by the developing roller to develop a photosensitive drum on whose surface an electrostatic latent image is formed.

[0004] The developing device has an opening through which the toner is transferred from the developing roller to the photosensitive drum, and a seal member is provided near the opening to prevent the toner and other substances inside the developing device from leaking out through the opening.

[0005] For example, as disclosed in Patent Document 1, a seal member (entrance seal) is formed in the vicinity of an opening of a developing container in which a developer storage section for storing toner is formed in a developing device, and is installed so as to seal the gap between the developing container and the developing roller. By installing the seal member in this manner, the toner and the like stored in the developing container (inside the developing device) is prevented from leaking to the outside from the gap between the developing container and the developing roller. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2013-190483 A Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, by providing a seal member as in the developing device disclosed in Patent Document 1, it is possible to prevent toner and the like from leaking from inside the developing device to the outside.

[0008] However, even in the developing device disclosed in Patent Document 1, when the developer carried on the developing roller rotates together with the developing roller and comes into contact with the sealing member, there was a possibility that some of the toner and the like would scatter and leak to the outside.

[0009] Therefore, there has been a demand for an image forming apparatus equipped with a developing device that can more reliably prevent toner and the like from leaking to the outside.

[0010] The present disclosure has been made in consideration of the above-mentioned circumstances, and has an object to provide an image forming apparatus including a developing device that can prevent toner and the like from leaking from inside the developing device. [Means for solving the problem]

[0011] An image forming apparatus according to one aspect of the present disclosure is an image forming apparatus equipped with a developing device, the developing device having a developer tank that contains a developer, a developer carrier installed near an opening of the developer tank, and a sealing member installed near a position where the opening and the developer carrier are close to each other, and is characterized in that when the developer carrier is not carrying the developer, the sealing member does not contact the developer carrier, and when the developer carrier is carrying the developer, the sealing member contacts the apex of a mountain-shaped portion formed by the developer on the developer carrier, or downstream of the apex of the mountain-shaped portion in the direction of rotation of the developer carrier.

[0012] This reduces the frictional force between the seal member and the developer in contact with the seal member 23 when the developer carrier is rotating. This makes it possible to prevent the developer from scattering and toner from leaking outside the developing device.

[0013] In addition, in the above-described image forming apparatus, when the developer carrier is carrying the developer, a tip of the sealing member may be positioned downstream of the apex in the rotation direction of the developer carrier.

[0014] This allows the seal member to absorb the momentum of the developer rotating together with the developer carrier, making it difficult for the developer to scatter and preventing toner from leaking outside the developing device.

[0015] In the image forming apparatus described above, the seal member may be movably installed and may be fixed in a predetermined state.

[0016] This allows the operator to place the seal member in a preferred position so as to prevent the developer from scattering, thereby more reliably preventing the toner from leaking outside the developing device.

[0017] The image forming apparatus described above may further include an auxiliary seal member disposed upstream of the seal member in the rotation direction of the developer carrier.

[0018] This makes it possible to prevent toner from scattering and leaking to the outside not only by the seal member but also by the auxiliary seal member, so that it is possible to more reliably prevent toner from leaking to the outside of the developing device.

[0019] The image forming apparatus described above may further include a scattering prevention roller disposed upstream in the rotation direction of the developer carrier from a position where the seal member is disposed.

[0020] As a result, the rotation of the anti-scattering roller creates an air flow toward the inside of the developing device, making it possible to prevent toner that has been scattered to the outside of the developing device from leaking out. Effect of the Invention

[0021] According to the present disclosure, it is possible to provide a developing device that can be made small and low cost and that is less susceptible to degradation in image quality, and an image forming apparatus including the same. [Brief description of the drawings]

[0022] [Figure 1] 1 is a front view perspectively showing a schematic configuration of an image forming apparatus according to a first embodiment of the present disclosure. [Diagram 2] 2 is a schematic cross-sectional view of a developing device in the image forming apparatus according to the first embodiment of the present disclosure. [Diagram 3] 3 is an enlarged view of a portion A of the developing device shown in FIG. 2, showing a state in which no developer is carried on the developing roller. FIG. [Figure 4] 3 is an enlarged view of a portion A of the developing device shown in FIG. 2, showing a state in which a developer is carried on a developing roller. FIG. [Diagram 5] 13 is an enlarged view of the periphery of a seal member of a developing device in an image forming apparatus according to a second embodiment of the present disclosure. FIG. [Figure 6] 13 is a schematic cross-sectional view of a developing device in an image forming apparatus according to a third embodiment of the present disclosure. FIG. [Figure 7] 13 is a schematic cross-sectional view of a developing device in an image forming apparatus according to a fourth embodiment of the present disclosure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described with reference to the drawings.

[0024] (First embodiment) An image forming apparatus 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 the image forming apparatus according to the first embodiment of the present disclosure.

[0025] 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 .

[0026] 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.

[0027] The document feeder 160 sequentially conveys one or more documents G one by one. The image reader 102 reads the documents G conveyed by the document feeder 160 one by one out of the one or more documents G.

[0028] The image reading section 130 includes an original placement table 130a on which an original G is placed, an original reading section 130b, and a scanning optical system 130c that reads the original.

[0029] 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. The document feeder 160 also includes a document placement tray 161 on which the document G is placed, and a document discharge tray 162 on which the document G discharged to the outside is stacked.

[0030] In the image forming apparatus 100, the document feeder 160 conveys the document G placed on the document placement tray 161 onto the document reading section 130b in the image reading section 130. The image reading section 130 scans the scanning optical system 130c to read the document placed on the document placement table 130a or reads the document G conveyed by the document feeder 160 to generate image data.

[0031] The image forming apparatus main body 101 includes an image transfer section 50, an optical scanning device 1, an intermediate transfer belt device 70, 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.

[0032] 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).

[0033] The image transfer unit 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 the image stations Pa, Pb, Pc, Pd includes a developing device 2, a photosensitive drum 3, a drum cleaning device 4, and a charger 5, and four types of toner images are formed by the image stations Pa, Pb, Pc, Pd. That is, the image forming apparatus 100 includes four developing devices 2, four photosensitive drums 3, four drum cleaning devices 4, and four chargers 5, each corresponding to black, cyan, magenta, and yellow.

[0034] The optical scanning device 1 exposes the surface of the photoreceptor drum 3 to light to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photoreceptor drum 3 to form a toner image on the surface of the photoreceptor drum 3. The drum cleaning device 4 removes and collects residual toner on the surface of the photoreceptor drum 3. The charger 5 uniformly charges the surface of the photoreceptor drum 3 to a predetermined potential. Through the series of operations described above, a toner image of each color is formed on the surface of each photoreceptor drum 3.

[0035] The intermediate transfer belt 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. There are four intermediate transfer rollers 6, which 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 transfer the toner images of the respective colors formed on the surfaces of the photosensitive drums 3 to the intermediate transfer belt 71.

[0036] 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 that is stretched between an intermediate transfer driving roller 72 and an intermediate transfer driven roller 73. A cleaning device 9 removes and collects waste toner that has not been transferred to the sheet P and remains on the surface of the intermediate transfer belt 71.

[0037] The secondary transfer device 11 forms a transfer nip area TN between the secondary transfer roller 11a and the intermediate transfer belt 71, and conveys a sheet P conveyed through a sheet conveying path S by pinching it in the transfer nip area TN. 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.

[0038] The fixing device 12 includes a fixing roller 31 and a pressure roller 32 that rotate while sandwiching the sheet P. The fixing device 12 sandwiches the sheet P, on which the toner image has been transferred, between the fixing roller 31 and the pressure roller 32, and applies heat and pressure to fix the toner image to the sheet P. Specifically, a heater, which is a heat source, is disposed inside the fixing roller 31, and the heat generated by the heater heats the surface of the fixing roller 31 that comes into contact with the sheet P on which the toner image has been transferred.

[0039] The paper feed cassette 18 is a cassette for storing sheets P used for image formation, and is provided below the optical scanning 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 is conveyed to the discharge roller 17 via the secondary transfer device 11 and the fixing device 12, 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 stops the sheet P once 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.

[0040] 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.

[0041] Furthermore, when forming an image on the back side of the sheet P in addition to the front side, the image forming apparatus 100 conveys the sheet P in the reverse direction from the discharge rollers 17 to a sheet inversion path Sr. The image forming apparatus 100 inverts the sheet P conveyed in the reverse direction and guides it again to the registration rollers 14. The image forming apparatus 100 also forms an image on the back side of the sheet P guided to the registration rollers 14 in the same manner as on the front side, and conveys the sheet P to the sheet discharge tray 141.

[0042] Next, the developing device 2 will be described in detail. Fig. 2 is a schematic cross-sectional view of the developing device in the image forming apparatus according to the first embodiment of the present disclosure. Fig. 3 is an enlarged view of part A of the developing device shown in Fig. 2, showing a state in which no developer is carried on the developing roller. Fig. 4 is an enlarged view of part A of the developing device shown in Fig. 2, showing a state in which developer is carried on the developing roller.

[0043] 2, the developing device 2 includes a developing roller 21, a doctor blade 22, a seal member installation portion 28, a seal member 23, transport members 24 and 25, and a developing tank 26. The developing roller 21 is disposed opposite the photosensitive drum 3 and is driven to rotate. The developing roller 21 is also disposed close to the photosensitive drum 3. The transport members 24 and 25 are also driven to rotate.

[0044] Developing tank 26 contains a two-component developer (hereinafter referred to as developer) containing toner and magnetic carrier. Transporting members 24 and 25 are located in developing tank 26, and are spaced apart from the inner wall surface of developing tank 26. Transporting members 24 and 25 each have a spiral transport blade, and when driven to rotate, transport the developer in developing tank 26 while stirring it. Specifically, transporting members 24 and 25 transport the developer in a direction perpendicular to the paper surface in FIG. 2. Transporting members 24 and 25 transport the developer in opposite directions, respectively, and the developer is circulated and transported in developing tank 26. The developer transported while being stirred by transporting member 24 is pumped up and carried by the outer circumferential surface of developing roller 21 that is rotating. The rotating direction of developing roller 21 is rotational direction F1.

[0045] The developing roller 21 is disposed near an opening 29 formed in the developing device 2, and a part of the developing roller 21 is exposed from the opening 29 to the outside, and the exposed part is disposed so as to face and approach the photosensitive drum 3. As a result, during an image forming operation, the toner in the developer carried by the developing roller 21 moves to the photosensitive drum 3. Specifically, in a nip portion where the developing roller 21 and the photosensitive drum 3 are close to each other, the developer carried on the outer circumferential surface of the developing roller 21 comes into contact with the photosensitive drum 3. In this nip portion, a developing bias voltage is applied to the developing roller 21, and the toner is supplied from the developer on the outer circumferential surface of the developing roller 21 to the electrostatic latent image on the outer circumferential surface of the photosensitive drum 3. The photosensitive drum 3 is also driven to rotate in a rotation direction F2, which is opposite to the rotation direction F1.

[0046] Doctor blade 22 is disposed such that its tip is spaced a predetermined distance from the peripheral surface of developing roller 21. The developer in developing tank 26 is pumped up onto the peripheral surface of developing roller 21 and carried in the form of a layer, and as developing roller 21 rotates in rotation direction F1, doctor blade 22 regulates the layer thickness of the developer carried on the peripheral surface of developing roller 21.

[0047] Further, a seal member installation portion 28 is provided near the opening 29, and a seal member 23 is fixedly disposed at the seal member installation portion 28. Specifically, the seal member 23 is disposed near the position where the opening 29 and the developing roller 21 are close to each other. The details will be described later, but the seal member 23 is disposed so as not to come into contact with the developing roller 21. The seal member 23 is flexible and made of a resin or the like. For example, it may be made of urethane or the like. The provision of the seal member 23 makes it possible to prevent the developer (toner) from scattering and leaking from inside the developing tank 26 to the outside.

[0048] Although not shown, multiple magnetic poles are arranged inside the developing roller 21. For example, there are magnetic poles for drawing up the developer in the developing tank 26 onto the circumferential surface of the developing roller 21, magnetic poles for supplying the toner to the photosensitive drum 3 during development, magnetic poles located downstream of the position facing the photosensitive drum 3 in the rotation direction F1 for holding and transporting the developer remaining on the circumferential surface of the developing roller 21 downstream after supplying the toner to the photosensitive drum 3, and magnetic poles for peeling off the developer remaining on the circumferential surface of the developing roller 21 and dropping it into the developing tank 26. In the developing roller 21, at the location where the magnetic poles for holding the developer are arranged after supplying the toner to the photosensitive drum 3, the developer rises up and forms a mountain shape on the circumferential surface of the developing roller 21 (see FIG. 4).

[0049] The developing roller 21, the transport members 24 and 25, and the photosensitive drum 3 are cylindrical and extend in a direction perpendicular to the paper surface of FIG. 2, and the seal member 23 is sheet-shaped and extends in a direction perpendicular to the paper surface of FIG.

[0050] Next, a more detailed description will be given of the seal member 23. When no developer is carried on the peripheral surface of the developing roller 21, as shown in Fig. 3, the seal member 23 is not in contact with the developing roller 21, and a tip 23a of the seal member 23 and the peripheral surface of the developing roller 21 are spaced apart by a predetermined distance.

[0051] During image formation, developer 27 is carried on the circumferential surface of developing roller 21 as shown in Fig. 4. As described above, in developing roller 21, at a location where a magnetic pole for holding developer 27 after toner is supplied to photosensitive drum 3 is disposed, developer 27 gathers and rises to form mountain-shaped portion 27a having apex 27b. Mountain-shaped portion 27a is formed in a mountain shape having apex 27b. Seal member 23 is disposed so as to come into contact with developer 27 at this mountain-shaped location.

[0052] Furthermore, the location where the seal member 23 and the developer 27 contact each other is preferably near the apex 27b of the mountain-shaped portion 27a. More preferably, the location where the seal member 23 and the developer 27 contact each other is downstream of the apex 27b in the rotation direction F1 (left side in FIG. 4), as shown in FIG. 4. Furthermore, it is preferable that the tip 23a of the seal member 23 is located downstream of the apex 27b in the rotation direction F1.

[0053] In this way, when the developer 27 is not carried on the peripheral surface of the developing roller 21, the seal member 23 does not contact the developing roller 21, and when the developer 27 is carried on the peripheral surface of the developing roller 21, the seal member 23 and the developer 27 come into contact with each other as described above, thereby preventing the toner (developer) from scattering from the developing tank 26 and leaking to the outside. Specifically, as in the first embodiment, the seal member 23 contacts the apex 27b of the mountain-shaped portion 27a of the developer 27 in the rotation direction F1 and the downstream side of the apex 27b, so that the resistance of the seal member 23 to the developer 27 is small, the toner is less likely to scatter, and it is possible to prevent the toner from leaking from the opening 29 to the outside of the developing device 2 (developing tank 26). In other words, in the configuration of the first embodiment, the frictional force between the developer 27 rotating together with the developing roller 21 and the seal member 23 is relatively small. Therefore, with this configuration, even though the developer 27 and the seal member 23 are in contact with each other, the toner is less likely to scatter, and leakage of the toner to the outside of the developing device 2 can be suppressed.

[0054] In addition, since the tip 23a is located downstream of the apex 27b in the rotational direction F1, the sealing member 23 absorbs the momentum of the developer 27 rotating together with the developing roller 21, thereby preventing the toner from scattering.

[0055] In this way, the frictional force between the developer 27 rotating together with the developing roller 21 and the seal member 23 can be reduced, and the seal member 23 can be configured to absorb the momentum of the developer 27 rotating together with the developing roller 21, thereby making it possible to prevent toner from leaking outside the developing device 2.

[0056] Second embodiment A second embodiment of the present disclosure will be described below. The second embodiment differs from the first embodiment in that the seal member 23 in the first embodiment is configured to be movable by an operator, but is otherwise similar to the first embodiment. Therefore, the following will describe the differences and omit a description of the other configurations. The same reference numerals are used for the same members as in the first embodiment.

[0057] The seal member 23 of the developing device 2 according to the second embodiment will be described with reference to the drawings. Fig. 5 is an enlarged view of the periphery of the seal member of the developing device in the image forming apparatus according to the second embodiment of the present disclosure.

[0058] As shown in FIG. 5, the seal member 23 is installed and supported by the seal member support portion 23b. The seal member support portion 23b is supported by the seal member installation portion 28 by the rotation shaft 23c. That is, the seal member support portion 23b is installed rotatably with respect to the seal member installation portion 28 by the rotation shaft 23c, and the seal member 23 is installed on the seal member support portion 23b, so that the seal member 23 can also rotate with respect to the seal member installation portion 28. This allows the operator to adjust the distance between the seal member 23 and the developing roller 21 by operating the seal member 23 (seal member support portion 23b). It is preferable to provide a mechanism that can fix the seal member 23 to the seal member installation portion 28. That is, it is preferable to provide a mechanism that can fix the seal member support portion 23b to the seal member installation portion 28 so as not to rotate. After the operator adjusts the distance between the seal member 23 and the developing roller 21, etc., the seal member 23 may be fixed to the seal member installation portion 28.

[0059] This allows the operator to adjust the arrangement of the seal member 23 relative to the developing roller 21 to a desired position. Therefore, the seal member 23 can be adjusted to a preferred position to reduce the frictional force between the developer 27 and the seal member 23. For example, after operating the image forming apparatus 100 and checking the condition of the seal member 23, etc., the seal member 23 can be adjusted to a preferred position, and toner leakage to the outside of the developing device 2 can be more reliably suppressed.

[0060] In addition, for example, while the image forming apparatus 100 is operating, the frictional force between the developer 27 carried on the peripheral surface of the developing roller 21 and the seal member 23 may be detected, and the position of the seal member 23 may be automatically adjusted to reduce the frictional force.

[0061] Third embodiment A third embodiment of the present disclosure will be described below. The third embodiment has a configuration in which an auxiliary seal member 41 is added to the configuration of the first embodiment, and other configurations are the same as those of the first embodiment. Therefore, the following will describe the points that are different from the first embodiment, and will omit a description of the other configurations. The same reference numerals are used to denote the same members as those of the first embodiment.

[0062] The developing device 2 according to the third embodiment will be described with reference to the drawings. Fig. 6 is a schematic cross-sectional view of the developing device in the image forming apparatus according to the third embodiment of the present disclosure.

[0063] 6, the developing device 2 is provided with an auxiliary seal member 41. The auxiliary seal member 41 is disposed upstream of the seal member 23 in the rotation direction F1 at the opening 29, and is disposed close to the developing roller 21 so as to close the opening 29. Note that the opening 29 is not completely closed by the auxiliary seal member 41, and a gap is formed between the auxiliary seal member 41 and the developing roller 21.

[0064] The auxiliary sealing member 41 is made of a flexible resin or the like, similar to the sealing member 23. For example, it may be made of urethane, etc. The auxiliary sealing member 41 is in the form of a sheet extending in a direction perpendicular to the paper surface of FIG.

[0065] The auxiliary seal member 41 is disposed so as not to come into contact with the developing roller 21 and also not to come into contact with the developer carried on the developing roller 21 .

[0066] Since auxiliary seal member 41 is provided, it is possible to prevent scattered toner from leaking to the outside through opening 29, which could not be prevented by seal member 23.

[0067] In this manner, according to the third embodiment, since not only the seal member 23 but also the auxiliary seal member 41 is provided, it is possible to prevent toner from leaking from the developing device 2 (developing tank 26) to the outside.

[0068] In place of the auxiliary seal member 41, a cover may be provided to prevent the scattered toner from leaking to the outside.

[0069] (Fourth embodiment) A fourth embodiment of the present disclosure will be described below. The fourth embodiment has a configuration in which a shatter prevention roller 42 is added to the configuration of the first embodiment, and other configurations are the same as those of the first embodiment. Therefore, the following will describe the differences from the first embodiment, and will omit a description of the other configurations. The same reference numerals are used for the same members as those of the first embodiment.

[0070] The developing device 2 according to the fourth embodiment will be described with reference to the drawings. Fig. 7 is a schematic cross-sectional view of the developing device in the image forming apparatus according to the fourth embodiment of the present disclosure.

[0071] 7, the developing device 2 is equipped with a scatter prevention roller 42. The scatter prevention roller 42 is installed adjacent to the developing roller 21 so as to close the opening 29 on the upstream side of the seal member 23 in the rotation direction F1. Note that the opening 29 is not completely closed by the scatter prevention roller 42, and a gap is formed between the scatter prevention roller 42 and the developing roller 21.

[0072] The scatter prevention roller 42 rotates in a rotation direction F3 which is the opposite direction to the rotation direction F1 of the developing roller 21. The scatter prevention roller 42 has a cylindrical shape extending in a direction perpendicular to the paper surface of FIG.

[0073] The anti-scattering roller 42 is disposed so as not to come into contact with the developing roller 21 and also not to come into contact with the developer carried by the developing roller 21.

[0074] Since the scattering prevention roller 42 is provided, it is possible to prevent scattering toner from leaking to the outside through the opening 29, which could not be prevented by the sealing member 23.

[0075] In addition, as the anti-scattering roller 42 rotates in the rotation direction F3, an air flow is formed in the space formed between the sealing member 23 and the anti-scattering roller 42, toward the downstream side in the rotation direction F1 (the sealing member 23 side), thereby preventing the scattered toner from leaking to the outside through the gap between the anti-scattering roller 42 and the developing roller 21.

[0076] As described above, according to the fourth embodiment, since not only the seal member 23 but also the scattering prevention roller 42 is provided, it is possible to prevent toner from leaking from the developing device 2 (developing tank 26) to the outside.

[0077] 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]

[0078] 1 Optical scanning device 2. Developing device 3 Photoconductor drum 4 Drum cleaning device 5. Charger 6 Intermediate transfer roller 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 Doctor Blade 23 Sealing material 23a tip 23b Seal member support part 23c Rotation axis 24, 25 Transport member 26 Developer tank 27 Developer 27a Mountain part 27b Vertex 28 Seal material installation section 29 Opening 31 Fuser roller 32 Pressure roller 41 Auxiliary seal member 42 Anti-scattering roller 50 Image transfer section 70 Intermediate transfer belt device 71 Intermediate transfer belt 72 Intermediate transfer drive roller 73 Intermediate transfer driven roller 100 Image forming device 101 Image forming apparatus main body 102 Image reading device 130 Image reading unit 130a Document stand 130b Document reading section 130c Scanning optics 140 Discharge section 141 Sheet output tray 160 Document feeder 161 Document tray 162 Document output tray F1, F2, F3 Rotation Direction G Manuscript P-sheet Pa, Pb, Pc, Pd Imaging Station S Sheet transport path Sr sheet inversion pathway TN Transfer nip area

Claims

1. An image forming apparatus including a developing device, the developing device includes a developer tank that contains a developer, a developer carrier disposed near an opening of the developer tank, and a seal member disposed near a position where the opening and the developer carrier are close to each other; When the developer carrying member does not carry the developer, the seal member does not contact the developer carrying member, an image forming apparatus characterized in that, when the developer carrier is carrying the developer, the sealing member is in contact with an apex of a mountain-shaped portion formed by the developer on the developer carrier, or downstream of the apex of the mountain-shaped portion in the rotation direction of the developer carrier.

2. 2. The image forming apparatus according to claim 1, an image forming apparatus characterized in that, when the developer carrier is carrying the developer, a tip of the seal member is located downstream of the apex in a rotation direction of the developer carrier.

3. 2. The image forming apparatus according to claim 1, The image forming apparatus according to claim 1, wherein the sealing member is movably installed and can be fixed in a predetermined state.

4. 2. The image forming apparatus according to claim 1, 13. An image forming apparatus comprising: an auxiliary seal member disposed upstream of a position where the seal member is disposed in a rotation direction of the developer carrier;

5. 2. The image forming apparatus according to claim 1, an anti-scattering roller disposed upstream of a position where the seal member is disposed in a rotation direction of the developer carrier;

Images