Developing device and image forming apparatus

Abstract

To provide a developing device and an image forming apparatus that suppress the accumulation of toner on a sealing material. [Solution] The developing device comprises a developing roller that is rotatable in a first direction, a regulating member that regulates the layer thickness of the developer carried on the developing roller, a cover member, and a sheet-like sealing material that has one end attached to the cover member and the other end in contact with the image carrier, the cover member having a first wall portion that covers part of the surface of the developing roller up to the position where the regulating member and the developing roller are closest to the image carrier, a second wall portion that extends from the tip end, which is the end opposite the regulating member side of the first wall portion, toward the upstream side in a second direction, which is a rotation direction opposite to the first direction, and an attachment portion provided on the end side opposite the tip end of the second wall portion, and the sealing material is attached to the attachment portion so that the position where it contacts the image carrier is located upstream in the second direction than the position on the image carrier that corresponds to the tip end.

Description

[Technical Field]

[0001] The present invention relates to a developing device, an image forming apparatus, and the like. [Background technology]

[0002] Conventionally, image forming apparatuses equipped with a seal material that suppresses the movement of floating toner have been known. For example, Patent Document 1 discloses a developing device and an image forming apparatus equipped with a cover portion having a seal material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-138986 Summary of the Invention [Problem to be solved by the invention]

[0004] The sealing material comes into contact with the image carrier (photosensitive drum), which has a charged surface, so toner tends to adhere to it due to electrostatic force. If toner that has accumulated on the sealing material falls, it could cause image defects.

[0005] According to some aspects of the present disclosure, it is possible to provide a developing device, an image forming apparatus, and the like that suppress the accumulation of toner on a sealing material. [Means for solving the problem]

[0006] One aspect of the present disclosure provides a developing roller that is rotatable in a first direction, which is a predetermined rotation direction, carries a developer including toner on its surface, and develops an electrostatic latent image formed on an image carrier that is rotatable in a second direction, which is a rotation direction opposite to the first direction; a regulating member that is provided a first distance, which is a predetermined distance, from the surface of the developing roller and regulates the layer thickness of the developer carried on the developing roller; a cover member that covers a part of the developing roller at a position between the regulating member and the image carrier; and a sheet-like sealing material that has one end attached to the cover member and the other end in contact with the image carrier, and the cover member is located at a position closer to the regulating member in the first direction. a first wall portion downstream of the regulating member and covering a portion of the surface of the developing roller up to the position where the developing roller is closest to the image carrier; a second wall portion extending from a tip end of the first wall portion opposite the regulating member side toward the upstream side in the second direction in a direction different from the first wall portion and covering a portion of the surface of the image carrier; and an attachment portion provided on the end side opposite the tip end of the second wall portion, wherein the one end side of the sealing material is attached to the attachment portion of the cover member so that the position where the sealing material contacts the image carrier is located upstream in the second direction of the image carrier relative to a position on the image carrier that corresponds to the tip end of the cover member.

[0007] Another aspect of the present disclosure relates to an image forming apparatus including the above-described developing device. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view illustrating the configuration of the developing device and the photosensitive drum according to the present disclosure. [Figure 3A] FIG. 2 is an exploded perspective view illustrating the configuration of a developing device according to the present disclosure. [Figure 3B] FIG. 2 is a perspective view illustrating the configuration of a developing device according to the present disclosure. [Figure 4] FIG. 2 is a cross-sectional view illustrating the configuration of a developing device according to the present disclosure. [Figure 5]4 is a cross-sectional view illustrating the configuration of a cover member of the developing device of the present disclosure. FIG. [Figure 6] FIG. 2 is a cross-sectional view illustrating the relationship between the various parts of the developing device according to the present disclosure. [Figure 7] FIG. 2 is a cross-sectional view illustrating the relationship between the various parts of the developing device according to the present disclosure. [Figure 8] FIG. 2 is a cross-sectional view illustrating the configuration of the tip portion. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the present embodiment will be described with reference to the drawings. In the drawings, identical or equivalent elements are designated by the same reference numerals, and duplicate explanations will be omitted. Note that the present embodiment described below does not unduly limit the content described in the claims. Furthermore, not all of the configurations described in the present embodiment are necessarily essential components of the present disclosure.

[0010] 1.Configuration example <Overall structure> The configuration of an image forming apparatus 1 equipped with a developing device 20 according to the present disclosure will be described using Figures 1 and 2. Figure 1 is a cross-sectional view showing the configuration of the image forming apparatus 1 according to the present disclosure. Figure 2 is an enlarged view of the configuration around the developing device 20 and the photosensitive drum 30 (image carrier) of the image forming apparatus 1. Note that in Figures 1 and 2, hatching indicating cross sections of components has been omitted as appropriate to make each component in the figures easier to see. The same applies to the other figures, where hatching indicating cross sections has been omitted as appropriate.

[0011] In the following description, the three axes x, y, and z represent coordinate axes that are perpendicular to each other as shown in FIG. 1. For example, the xz plane corresponds to a horizontal plane when the image forming apparatus 1 is installed on a horizontal floor. For example, the image forming apparatus 1 has a substantially rectangular housing, and the x-axis is an axis along one horizontal side of the housing, and the z-axis is an axis along the other horizontal side and is an axis perpendicular to the x-axis. The y-axis corresponds to a vertical axis, with the positive direction of the y-axis representing an upward vertical direction and the negative direction of the y-axis representing a downward vertical direction (the direction of gravity). The directions of the x, y, and z-axes are the same in FIG. 2 and subsequent figures.

[0012] The image forming apparatus 1 according to the present disclosure may be a multifunction peripheral (MFP) having a scanner function, a copy function, a printer function, a facsimile function, and the like. For example, the image forming apparatus 1 may transmit an image of a document read by the image reading device 10 to an external device (corresponding to the scanner function). The image forming apparatus 1 may also form an image of the read document or an image received from an external device on a sheet in color or monochrome (corresponding to the copy function, printer function, and facsimile function). Note that the image forming apparatus 1 is not limited to a multifunction peripheral, and may be a device having only a printer function.

[0013] As shown in Fig. 1, the image forming apparatus 1 includes an image reading device 10, a developing device 20, a photosensitive drum 30, an optical scanning device 40, a transfer roller 50, a fixing device 60, a sheet transport path 70, a paper feeder 80, etc. As shown in Fig. 2, a charging roller 31, a static eliminator 32, and a cleaning blade 33 may be provided at positions facing the surface of the photosensitive drum 30. Each component will be described below.

[0014] The image reading device 10 reads a document or a document transported from an automatic document feeder (ADF) to generate image data. The image forming device 1 handles image data corresponding to a monochrome image using, for example, a single color (e.g., black). For example, FIG. 1 illustrates the image forming device 1 provided with one developing device 20 and one photosensitive drum 30 corresponding to black. However, the image forming device 1 may also handle image data corresponding to a color image using each of the colors black (K), cyan (C), magenta (M), and yellow (Y). In this case, the image forming device 1 may be provided with four sets of developing devices 20 and photosensitive drums 30 corresponding to black, cyan, magenta, and yellow, respectively.

[0015] The photosensitive drum 30 rotates in a second direction R2, which is counterclockwise in FIGS. 1 and 2. The photosensitive drum 30 has a drum-shaped substrate and a photoconductive layer formed as a thin film on the surface of the substrate. The substrate is made of a metal such as aluminum. The photoconductive layer is made of an organic photoconductor (OPC) or amorphous silicon (a-Si), for example.

[0016] The charging roller 31 uniformly charges the surface of the photosensitive drum 30. However, instead of the charging roller 31, a charging device such as a charging brush may be used.

[0017] The optical scanning device (exposure device) 40 irradiates the image formation area on the surface of the photosensitive drum 30 with light along an exposure path in the main scanning direction in accordance with image information. In FIGS. 1 and 2, the exposure path of the optical scanning device 40 is illustrated by a dashed line. The main scanning direction is the direction in which light moves on the surface of the photosensitive drum 30, and corresponds to the depth direction (direction along the z-axis) in FIGS. 1 and 2. The direction perpendicular to the main scanning direction is called the sub-scanning direction, and the sub-scanning direction here corresponds to the second direction R2, which is the rotation direction. In this way, the optical scanning device 40 forms an electrostatic latent image in the image formation area on the surface of the photosensitive drum 30. The optical scanning device 40 may include, for example, a laser or an LED (Light Emitting Diode).

[0018] The developing device 20 supplies toner onto the surface of the photosensitive drum 30 by a developing electric field formed between the photosensitive drum 30 and the developing device 20. In this way, the developing device 20 visualizes the electrostatic latent image into a toner image. The detailed configuration of the developing device 20 will be described later.

[0019] A sheet of paper P, which is an example of a recording medium, is pulled out of the paper feeder 80 by a pickup roller 81 and transported through the sheet transport path 70. Specifically, the sheet of paper P is transported upward in FIG. 1 between the photosensitive drum 30 and the transfer roller 50. The fixing device 60 is disposed downstream of the transfer roller 50 in the paper transport direction.

[0020] The transfer roller 50 transfers the toner image onto the paper P using a transfer bias, which is a predetermined voltage or current applied from a transfer power supply. The fixing device 60 fixes the toner image to the paper P by thermocompressing the toner transferred onto the paper P to the paper P.

[0021] The charge eliminating device 32 removes the charge on the surface of the photosensitive drum 30. The cleaning blade 33 removes the toner remaining on the surface of the photosensitive drum 30 after the toner image has been transferred onto the paper P.

[0022] The surface of the photosensitive drum 30, from which the charge has been removed by the static eliminator 32, is then uniformly charged again by the charging roller 31. An electrostatic latent image is formed on the surface of the photosensitive drum 30 by the optical scanning device 40. The electrostatic latent image is converted into a toner image by the developing device 20. The toner image is transferred to paper P by the transfer roller 50 and fixed to the paper P by the fixing device 60. Any toner remaining on the surface of the photosensitive drum 30 is removed by the cleaning blade 33, and the surface of the photosensitive drum 30 is then neutralized by the static eliminator 32. This image formation process is repeated as necessary.

[0023] <Developing device> An overview of the developing device 20 of the present disclosure will be described using the above-mentioned FIG. 2 and FIGS. 3A to 4. FIG. 3A is an exploded perspective view illustrating the mounting positions of each part included in the developing device 20, and FIG. 3B is a perspective view of the developing device 20 with the parts mounted thereto. FIG. 4 is a cross-sectional view illustrating the configuration of the developing device 20. Note that in the present disclosure, when illustrating the relationship (positional relationship, distance, etc.) between the developing device 20 and other members (e.g., the photosensitive drum 30), the relationship refers to the relationship when the developing device 20 is mounted at a predetermined position in the image forming apparatus 1. The predetermined position here refers to a position where the image forming apparatus 1 can operate normally, and is, for example, the position described above with reference to FIG. 1.

[0024] As shown in the figure, the developing device 20 includes a housing 28 as a container for containing a developer, a developer tank 26 provided in the housing 28, two stirring and conveying rollers 25a and 25b, a developing roller 21, and a regulating member 22. In this embodiment, the regulating member 22 is a doctor blade.

[0025] Developer tank 26 stores developer (not shown). The developer used is a two-component developer containing non-magnetic toner and magnetic carrier. Stirring and conveying rollers 25a and 25b stir the developer stored in developer tank 26. This stirring generates friction between the toner and magnetic carrier contained in the developer, and this friction charges the non-magnetic toner. The magnetic carrier and toner are supplied to developer tank 26 through toner supply port 27.

[0026] The developing roller 21 is rotatable in a first direction R1, which is a predetermined rotation direction, carries a developer containing toner on its surface, and develops an image carrier with the developer carried on its surface. Developing an image carrier refers to developing an electrostatic latent image formed on the image carrier. The image carrier is, for example, a photosensitive drum 30 that is rotatable in a second direction R2, which is a rotation direction opposite to the first direction R1, and on which an electrostatic latent image is formed.

[0027] For example, the developing roller 21 is partially exposed from the housing 28 and rotates in a first direction R1, which is clockwise in Fig. 2. The developing roller 21 is disposed opposite the photosensitive drum 30, which rotates in a second direction R2, which is the opposite direction to the first direction R1. As shown in the figure, the housing 28 has an opening at its top (positive x-axis direction and positive y-axis direction), and the developing roller 21 is disposed so as to face the photosensitive drum 30 through this opening.

[0028] As shown in Figures 3A and 3B, a regulating member 22, a cover member 23, and a sealant 24 are provided in the opening. The cover member 23 is a member that covers a part of the developing roller 21 at a position between the regulating member 22 and the photosensitive drum 30 (image carrier). The sealant 24 is a sheet-like member that has one end attached to the cover member 23 and the other end that contacts the photosensitive drum 30. Details of the cover member 23 and the sealant 24 will be described later using Figures 5 to 8.

[0029] The developing roller 21 includes a non-magnetic, cylindrical sleeve portion and a cylindrical, magnetic magnet roll disposed inside the sleeve portion. The sleeve portion is rotatably supported by a shaft in the housing 28. The rotation of the sleeve portion causes the developing roller 21 to rotate in a first direction R1. A potential is applied to the sleeve portion from a power source so as to generate a potential difference between the sleeve portion and the photosensitive drum 30. Multiple magnetic poles are formed on the circumferential surface of the developing roller 21 due to the magnetism of the magnet roll.

[0030] The magnet roll magnetically attracts the magnetic carrier with its magnetic force, and forms developer ears (magnetic ears) called a magnetic brush, consisting of the magnetic carrier and toner, on the surface of the sleeve portion, which is the circumferential surface of the developing roller 21. Details of the magnetic poles formed by the magnet roll will not be explained here. The developing roller 21 transports the developer to the opposing portion 90 (developing nip) closest to the photosensitive drum 30 by rotating the sleeve portion in the first direction R1.

[0031] The regulating member 22 is provided a predetermined first distance d1 away from the surface of the developing roller 21 and regulates the thickness of the developer layer carried on the developing roller. For example, the regulating member 22 is a doctor blade and is disposed upstream of the opposing portion 90 in the rotational direction (first direction R1) of the developing roller 21, in close proximity to the circumferential surface of the developing roller 21 with a gap of the first distance d1 provided between the regulating member 22 and the circumferential surface of the developing roller 21. In this way, the doctor blade uses the gap to limit the amount of pumped-up developer that passes through, thereby regulating the thickness of the developer layer. Note that the regulating member 22 is not limited to a blade-shaped doctor blade, and regulating members 22 of other shapes may also be used.

[0032] Next, the cover member 23 and the seal material 24 will be described in detail with reference to Figures 5 and 6. Figure 5 is an enlarged cross-sectional view (perspective view) of a portion of the cover member 23 and the regulating member 22, and Figure 6 is a cross-sectional view illustrating the positional relationship between the developing roller 21, the regulating member 22, the cover member 23, the seal material 24, and the photosensitive drum 30.

[0033] 5 and 6, the cover member 23 is a member that covers the developing roller 21 from above (the positive y-axis direction side) in the area between the regulating member 22 and the photosensitive drum 30. The cover member 23 may include a first wall portion 23a, a tip portion 23b, a second wall portion 23c, and an attachment portion 23d.

[0034] The first wall portion 23a is downstream of the regulating member 22 in the first direction R1 and covers a part of the surface of the developing roller 21 up to the position (opposing portion 90, development nip) where the developing roller 21 is closest to the photosensitive drum 30 (image carrier). For example, the first wall portion 23a is a curved wall portion that covers the developing roller 21 from above at a position spaced a second distance d2 from the developing roller 21.

[0035] The tip portion 23b represents the end portion of the first wall portion 23a opposite to the restricting member 22. In other words, the tip portion 23b may be the end portion of the first wall portion 23a on the downstream side in the first direction R1.

[0036] The second wall portion 23c extends from the tip end 23b toward the upstream side in the second direction R2 in a direction different from that of the first wall portion 23a. In the example shown in Fig. 6, the direction in which the second wall portion 23c extends is the negative direction of the x-axis and the positive direction of the y-axis. By extending upstream in the second direction R2, the second wall portion 23c covers a portion of the surface of the photosensitive drum 30.

[0037] The attachment portion 23d is provided on the end side of the second wall portion 23c opposite to the tip portion 23b. The attachment portion 23d may be, for example, a wall portion having a flat surface facing in a different direction from the second wall portion 23c.

[0038] One end of the sealant 24 is attached to the attachment portion 23d of the cover member 23, and the tip portion of the other end contacts the photosensitive drum 30. The sealant 24 may be attached directly to the attachment portion 23d, or may be attached via a spacer as shown in FIG.

[0039] In the developing device 20, as the developing roller 21 rotates in the first direction R1, an airflow is generated in the region between the developing roller 21 and the first wall portion 23a in the first direction R1. In this case, it is conceivable that some of the toner contained in the developer will be separated from the magnetic brush by the airflow and become airborne. In this regard, the provision of the sealant 24 prevents the airborne toner from being released from the upper portion (positive direction of the y-axis) of the developing device 20. As shown in FIGS. 1 and 2, the upper portion of the developing device 20 is provided with a charging device including a charging roller 31, an optical scanning device 40, and the like. The provision of the sealant 24 prevents problems caused by toner adhering to these components.

[0040] However, since the sealing material 24 needs to properly seal the area between the cover member 23 and the photosensitive drum 30, one end (the end opposite the attachment position of the attachment portion 23d) comes into contact with the photosensitive drum 30 as described above. The surface area of ​​the photosensitive drum 30 exposed by the optical scanning device 40 is given, for example, a low potential in order to receive toner from the developing roller 21. In other words, the exposed surface of the photosensitive drum 30 is in a state that easily attracts toner electrostatically, and therefore the sealing material 24 in contact with the photosensitive drum 30 also becomes in a state where toner easily adheres thereto.

[0041] Therefore, in the method disclosed herein, the sealing material 24 is provided on the cover member 23 so that the position P1 at which it comes into contact with the photosensitive drum 30 (image carrier) is located upstream in the second direction R2 of the position P2 on the image carrier that corresponds to the tip 23b of the cover member 23.

[0042] As shown in FIG. 6, position P2 is, for example, the position on the surface of the photosensitive drum 30 at which the distance to the leading end 23b is shortest. Specifically, position P2 corresponds to the intersection of a line connecting the center of the photosensitive drum 30 and the leading end 23b of the cover member 23 with the surface of the photosensitive drum 30. Position P1 is the position at which the sealing material 24 and the photosensitive drum 30 come into contact, and FIG. 6 illustrates a position corresponding to the end of the sealing material 24. Note that position P1 at which the sealing material 24 comes into contact with the photosensitive drum 30 (image carrier) may be an area having a certain range along the second direction R2 (in this case, the sealing material 24 comes into surface contact with the photosensitive drum 30).

[0043] Here, position P1 is located upstream in the second direction R2 from position P2 by a distance L1 in FIG. 6 . That is, when viewed from the developing roller 21, the tip 23b of the cover member 23 is located relatively close, and the sealant 24 (particularly the contact portion with the photosensitive drum 30) is located farther away than the tip 23b. As a result, even if toner scatters in the region between the first wall portion 23a and the developing roller 21, the toner is blocked by the cover member 23 (particularly the portion near the tip 23b) and is therefore less likely to reach the sealant 24. Therefore, the sealant 24 prevents toner from scattering outside the developing device 20 while also preventing excessive toner from adhering to the sealant 24. As a result, it is possible to prevent a large amount of toner that has scattered onto the sealant 24 from adhering and agglomerating. In other words, the toner that has adhered to the sealant 24 and aggregated into clumps is prevented from falling off and being developed, thereby reducing the occurrence of image defects.

[0044] Furthermore, when considering the relationship between the distances, the second distance d2, which is the distance between the first wall portion 23a and the surface of the developing roller 21, may be longer than the first distance d1, which is the distance between the regulating member 22 and the surface of the developing roller 21. This makes it possible to appropriately supply the desired amount of developer to the photosensitive drum 30.

[0045] Furthermore, the second wall portion 23c is formed so that the distance between the second wall portion 23c and the surface of the photosensitive drum 30 (image carrier) is shortest at the tip portion 23b and increases as it moves from the tip portion 23b toward the upstream side in the second direction R2. For example, in FIG. 6, the distance between the second wall portion 23c and the photosensitive drum 30 at the tip portion 23b is a third distance d3. Furthermore, at a position on the second wall portion 23c closer to the attachment portion 23d than the tip portion 23b, the distance between the second wall portion 23c and the photosensitive drum 30 is longer than the third distance d3. Specifically, the distance between the second wall portion 23c and the surface of the photosensitive drum 30 increases compared to the third distance d3 as it moves away from the tip portion 23b.

[0046] As described above, an airflow may occur in the region between the first wall portion 23a and the developing roller 21 in the direction along the first direction R1, causing toner to scatter. However, by setting the direction in which the second wall portion 23c extends as described above, the entrance portion to the region between the second wall portion 23c and the photosensitive drum 30 is narrowed and restricted. Therefore, toner that has scattered along the first direction R1 is less likely to enter the region between the second wall portion 23c and the photosensitive drum 30, making it possible to further suppress adhesion and accumulation of toner on the sealing material 24.

[0047] 6, in the region between the second wall portion 23c and the photosensitive drum 30 where the seal member 24 is not present—in other words, in the region from the tip end 23b of the cover member 23 to a distance L1 upstream in the second rotation direction R2—the second wall portion 23c is stationary and the photosensitive drum 30 rotates along the second direction R2. In other words, in this range, airflow along the second direction R2 is likely to occur, for example, an airflow in the direction indicated by AF in FIG. 6 is generated. In other words, even when the direction of the airflow is taken into consideration, scattered toner is less likely to enter the region between the second wall portion 23c and the photosensitive drum 30, which further reduces adhesion and accumulation of toner on the seal member 24.

[0048] Furthermore, the shortest distance between tip end 23b and the surface of photosensitive drum 30 (image carrier) may be shorter than the shortest distance between tip end 23b and the surface of the developing roller. In the example of Fig. 6, the shortest distance between tip end 23b and the surface of photosensitive drum 30 is third distance d3, and the shortest distance between tip end 23b and the surface of developing roller 21 is second distance d2. In other words, in the method disclosed herein, d2 may be greater than d3.

[0049] In this way, the toner scattered near the tip 23b can easily move through the relatively wide region between the first wall 23a and the developing roller 21, and is less likely to move into the relatively narrow region between the second wall 23c and the photosensitive drum 30. As a result, the scattered toner is less likely to enter the region between the second wall 23c and the photosensitive drum 30, which further reduces adhesion and accumulation of toner on the sealing material 24.

[0050] 2. Variations 7 is another cross-sectional view illustrating the positional relationship between the developing roller 21, the regulating member 22, the cover member 23, the seal member 24, and the photosensitive drum 30. As shown in FIG.

[0051] As shown in FIG. 7, in this modified example, the first wall portion 23a covering the developing roller 21 in the region between the regulating member 22 and the photosensitive drum 30 may have a configuration in which the distance from the developing roller 21 varies depending on its position. Specifically, the first wall portion 23a includes a third wall portion 23e, which is a portion of the first wall portion 23a on the regulating member 22 side and is located at a distance from the surface of the developing roller 21 that corresponds to the second distance d2, and a fourth wall portion 23f, which is a portion of the first wall portion 23a on the tip end portion 23b side and is located at a distance from the surface of the developing roller 21 that is longer than the second distance d2. In the example shown in FIG. 7, the third wall portion 23e is a curved surface that maintains a constant distance from the developing roller 21 (the second distance d2), similar to the example described above with reference to FIG. 6. The fourth wall portion 23f is a flat surface whose shortest distance from the developing roller 21 is the fourth distance d4. As shown in FIG. 7, the first wall portion 23a may include a fifth wall portion that connects the third wall portion 23e and the fourth wall portion 23f.

[0052] This configuration makes it possible to increase the space downstream (toward the tip end 23b, toward the photosensitive drum 30) in the first direction R1 in the region between the first wall portion 23a and the developing roller 21 compared to the upstream (toward the restricting member 22). Therefore, when an airflow in the first direction R1 is generated by the rotation of the developing roller 21, the speed q2 of the airflow downstream can be made slower than the speed q1 of the airflow upstream. This relatively slower airflow also slows the movement of toner near the tip end 23b. As a result, scattered toner is less likely to enter the region between the second wall portion 23c and the photosensitive drum 30, further suppressing the adhesion and accumulation of toner on the sealing material 24.

[0053] 7, the sealant 24 is provided on the cover member 23 so that position P1, where the sealant 24 contacts the photosensitive drum 30 (image carrier), is located upstream in the second direction R2 of position P2, which corresponds to the leading edge 23b of the image carrier. For example, as shown in FIG. 7, position P1 is located a distance L2 upstream in the second direction R2 from position P2. This makes it possible to further suppress adhesion and accumulation of toner on the sealant 24. Note that while FIGS. 6 and 7 show an example where L1 > L2, various modifications can be made to the specific positions of positions P1 and P2 on the photosensitive drum 30 and the distance between them.

[0054] The distance between the second wall portion 23c and the surface of the photosensitive drum 30 is shortest (third distance d3) at the tip end 23b and increases from the tip end 23b toward the upstream side in the second direction R2. The third distance d3 in the configuration described above with reference to FIG. 6 and the third distance d3 in the configuration shown in FIG. 7 may be the same or different. This makes it possible to further suppress adhesion and accumulation of toner on the sealing material 24.

[0055] Furthermore, the shortest distance between the tip end 23b and the surface of the photosensitive drum 30 may be shorter than the shortest distance between the tip end 23b and the surface of the developing roller 21. This makes it possible to further suppress adhesion and accumulation of toner on the sealing material 24.

[0056] Here, the tip portion 23b of the cover member 23 may be chamfered. Fig. 8 is a cross-sectional view illustrating the configuration of the tip portion 23b. As shown in Fig. 8, the end of the first wall portion 23a opposite to the restricting member 22 may be chamfered, and the tip portion 23b may correspond to the chamfered portion.

[0057] In this case, the shortest distance between the tip end 23b and the surface of the developing roller 21 corresponds to the fifth distance d5, which is the distance from the relatively lower (negative y-axis direction) corner of the two chamfered corners to the developing roller 21. The shortest distance between the tip end 23b and the surface of the photosensitive drum 30 corresponds to the distance from the relatively upper (positive y-axis direction) corner of the two chamfered corners to the photosensitive drum 30, which corresponds to the third distance d3. When considering the distance from the tip end 23b in this way, the end point on the tip end 23b side may be located at a different position depending on the target component. In this case, the relationship d5>d3 holds, further suppressing toner adhesion and accumulation on the sealing material 24.

[0058] Furthermore, mounting portion 23d of cover member 23 may extend from the end opposite tip portion 23b of second wall portion 23c in a direction different from that of second wall portion 23c, and may be provided so that the distance from the surface of photosensitive drum 30 (image carrier) increases with increasing distance from the end opposite tip portion 23b of second wall portion 23c. In this way, mounting portion 23d can be disposed at a position away from photosensitive drum 30, as shown in FIG. 7.

[0059] As a result, as shown in FIG. 7, the gap between the second wall portion 23c and the photosensitive drum 30 is narrowed to prevent scattered toner from entering, while a relatively wide space (a gap sufficiently wider than the third distance d3) is secured between the mounting portion 23d and the photosensitive drum 30. This space allows the sealant 24 to be positioned appropriately. While both the second wall portion 23c and the mounting portion 23d have surfaces whose distance from the photosensitive drum 30 increases toward the upstream side in the second direction R2, the method disclosed herein provides a greater change in the distance from the photosensitive drum 30 to the mounting portion 23d ( FIG. 7 ). In other words, when one end of the sealant 24 is attached to the mounting portion 23d, the distance between the sealant 24 and the photosensitive drum 30 decreases toward the other end of the sealant 24, but the degree of this decrease can be increased. As a result, the sealant 24 and the photosensitive drum 30 come into contact at a position close to the mounting portion 23d, allowing the sealant 24 to be positioned appropriately. Specifically, it becomes easy to provide the seal material 24 so that the position P1 is further upstream in the second direction R2 than the position P2.

[0060] 6, the mounting portion 23d may be a wall surface whose distance from the photosensitive drum 30 increases toward the upstream side in the second direction R2. The sealing material 24 may be attached directly to the mounting portion 23d or may be attached via a spacer.

[0061] Furthermore, the method of the present disclosure is not limited to being applied to the developing device 20 described above, but may also be applied to the image forming apparatus 1 including the developing device 20.

[0062] Although the present embodiment has been described in detail above, those skilled in the art will readily understand that many modifications are possible without substantially departing from the novel features and advantages of the present embodiment. Therefore, all such modifications are intended to be included within the scope of the present disclosure. For example, a term described at least once in the specification or drawings together with a different term with a broader or equivalent meaning may be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of the present embodiment and modifications are also included within the scope of the present disclosure. Furthermore, the configurations and operations of the image forming apparatus, developing device, etc. are not limited to those described in the present embodiment, and various modifications are possible. [Explanation of symbols]

[0063] REFERENCE SIGNS LIST 1 image forming apparatus, 10 image reading device, 20 developing device, 21 developing roller, 22 regulating member, 23 cover member, 23a first wall portion, 23b tip portion, 23c second wall portion, 23d mounting portion, 23e third wall portion, 23f fourth wall portion, 24 sealing material, 25a, 25b stirring and conveying roller, 26 developing tank, 27 toner supply port, 28 housing, 30 photosensitive drum, 31 charging roller, 32 static eliminator, 33 cleaning blade, 40 Optical scanning device, 50 Transfer roller, 60 Fixing device, 70 Sheet transport path, 80 Paper feeder, 81 Pickup roller, 90 Opposing portion (developing nip), d1 First distance, d2 Second distance, d3 Third distance, d4 Fourth distance, d5 Fifth distance, L1, L2 Distance (between P1 and P2), P Paper, P1 Contact position between sealing material and photosensitive drum, P2 Position corresponding to leading edge, q1 Air flow on upstream side, q2 Air flow on downstream side, R1 First direction, R2 Second direction

Claims

1. a developing roller that is rotatable in a first direction, which is a predetermined rotation direction, carries a developer containing toner on its surface, and develops an electrostatic latent image formed on an image carrier that is rotatable in a second direction, which is a rotation direction opposite to the first direction; a regulating member provided at a first distance, which is a predetermined distance, from the surface of the developing roller, and configured to regulate the thickness of the developer layer carried on the developing roller; a cover member for covering a part of the developing roller at a position between the regulating member and the image carrier; a sheet-like sealing material having one end attached to the cover member and the other end in contact with the image carrier; Equipped with The cover member is a first wall portion that is downstream of the regulating member in the first direction and covers a part of the surface of the developing roller up to a position where the developing roller is closest to the image carrier; a second wall portion extending from a tip end portion of the first wall portion opposite to the regulating member side toward an upstream side in the second direction in a direction different from the first wall portion, and covering a part of the surface of the image carrier; an attachment portion provided on an end side of the second wall portion opposite the tip portion, The sealing material is the one end side is attached to the attachment portion of the cover member so that a position of contact with the image carrier is located upstream in the second direction of a position of the image carrier corresponding to the tip end portion of the cover member; Developing device.

2. 2. The developing device according to claim 1, The first wall portion is a distance between the first wall portion and the surface of the developing roller is longer than the first distance; The second wall portion is the developing device is provided so that the distance between the second wall portion and the surface of the image carrier is shortest at the tip end portion and increases from the tip end portion toward the upstream side in the second direction.

3. 2. The developing device according to claim 1, The first wall portion is a third wall portion that is a part of the first wall portion on the regulating member side and is provided at a position where the distance from the surface of the developing roller corresponds to the second distance; a fourth wall portion that is a part of the first wall portion on the tip end side and is provided at a position that is a distance from the surface of the developing roller that is longer than the second distance.

4. 2. The developing device according to claim 1, a developing device in which the shortest distance between the tip portion and the surface of the image carrier is shorter than the shortest distance between the tip portion and the surface of the developing roller;

5. 2. The developing device according to claim 1, The mounting portion is A developing device that extends from an end portion opposite the tip portion of the second wall portion in a direction different from the second wall portion, and is arranged so that the distance from the surface of the image carrier increases as the developing device moves away from the end portion opposite the tip portion of the second wall portion.

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

Images