JP4659423B2 - Developing device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a developing device that performs development by electrophotographic development using magnetic toner (hereinafter sometimes referred to as “toner”), and in particular, development that prevents scattering of magnetic toner outside the development area. The present invention relates to an apparatus and an image forming apparatus including the apparatus.

  In general, in an image forming apparatus such as an electrophotographic developing printer, a facsimile, or a copying machine, a developer is used to form a toner image on the surface of a photosensitive member on which an electrostatic latent image based on image data of an original is formed. Is provided.

  Conventionally, such a developing apparatus is provided with a seal member for preventing the toner from flowing out of the developing area. As the seal member, for example, a magnetic seal member made of a magnetic material is used, and at both ends in the longitudinal direction of the developing roller, the magnetic seal member is spaced apart from the outer peripheral surface of the developing sleeve. In general, the toner is prevented from flowing out. More specifically, the magnetic toner carried on the developing sleeve by the magnetic force of the fixed magnet is restrained by a magnetic field formed in the gap between the end of the fixed magnet and the magnetic seal member. Then, by forming a magnetic brush by the rising of magnetic toner in the gap between the developing sleeve and the magnetic seal member, the magnetic toner that is about to flow out is blocked and a sealing action is performed.

  However, the sealing performance of the magnetic seal member is not sufficient. For example, in the case of a cartridge type in which the developing device is detachable from the image forming apparatus, toner leakage is likely to occur due to vibration or impact during the detachment operation. However, there is a problem that sufficient sealing performance cannot be exhibited only by the magnetic seal member.

In view of this, there has been proposed a developing device in which a magnetic seal member is disposed at both ends in the longitudinal direction of the developing roller with a constant interval, and a groove is provided on the inner peripheral surface of the magnetic seal member. The groove is formed in a direction to guide the magnetic toner to the developing region side of the developing container. By providing the groove, a magnetic brush having a strong toner binding force is formed to prevent toner leakage ( For example, see Patent Document 1).
JP-A-8-137275

  Here, in recent years, in image forming apparatuses such as copying machines, aiming at high-speed printing, the speed of rotation of the developing sleeve has been increased. In a developing device used in an image forming apparatus (hereinafter referred to as “high speed machine”) that supports such high speed, the force for pushing magnetic toner to the outside increases. Accordingly, when the pushing force becomes larger than the magnetic restraining force of the magnetic seal member, the magnetic toner easily passes through the magnetic seal member and easily leaks out of the development area.

  Therefore, even in such a high-speed machine, it is necessary to effectively prevent toner leakage. However, in the configuration in which the groove portion is provided on the inner peripheral surface of the magnetic seal member as in the above-described conventional developing device, such a high-speed machine has such a structure. There is a problem that toner scattering in a high-speed machine cannot be effectively prevented.

  Accordingly, the present invention has been made in view of the above-described problems. Even in an image forming apparatus that supports high speed, it is possible to effectively prevent toner leakage and to exhibit stable sealing performance over a long period of time. An object of the present invention is to provide a developing device that can be used, and an image forming apparatus including the developing device.

In order to achieve the above object, the developing device of the present invention comprises a developing sleeve that includes a fixed magnet roller having a plurality of magnetic poles and that is rotatably supported to guide toner onto the surface of the photoreceptor. A developing device comprising: a developing roller; and a magnetic seal member disposed at a longitudinal end portion of the developing sleeve at a distance from an outer peripheral surface of the developing sleeve. A tape member is wound around the outer peripheral surface, and the tape member includes a first tape portion wound around the outer peripheral surface of the developing sleeve and a second tape portion wound around the outer peripheral surface of the first tape portion. The step portion is constituted by a first step portion formed by the first tape portion and a second step portion formed by the second tape portion, The two step portions are provided outside the first step portion in the longitudinal direction of the developing sleeve, and a taper portion is provided on the toner carrying side of the developing sleeve of the second tape portion. The taper portion is inclined from the inner side to the outer side in the longitudinal direction of the developing sleeve as it goes from the rear side to the front side in the rotation direction of the developing sleeve, and is positioned on the toner carrying side of the developing sleeve. An end of the first step portion is a first inner end, an end of the second step located on the toner carrying side of the developing sleeve is a second inner end, and a toner carrying side of the developing sleeve The end of the magnetic seal member positioned at the inner side is the seal inner end, and the end of the magnetic seal member positioned on the opposite side to the inner end of the seal is the outer end of the seal. Characterized in that parts and the second inner end portion is provided between the seal inner end position corresponding to the position and the sealing outer end corresponding to the longitudinal direction of the developing sleeve.

Cellophane tape or Teflon (registered trademark) tape is used as the tape member .

  An image forming apparatus according to the present invention includes any one of the developing devices described above.

According to the developing device of the present invention, the developing roller is provided with a stepped portion by setting the outer diameter of the end portion of the developing roller to be larger than the outer diameter of the main body portion of the developing roller. Therefore, the toner that passes through the magnetic seal member and flows out of the developing area is physically blocked by the stepped portion, so that it is possible to prevent the toner from flowing out of the developing area. As a result, even in an image forming apparatus that supports high speed, it is possible to prevent toner leakage and to exhibit stable sealing performance over a long period of time.
Further, by winding a tape member around the end portion of the developing roller, the outer diameter of the end portion of the developing roller is set larger than the outer diameter of the main body portion of the developing roller, and a step portion is provided on the developing roller. . Therefore, even in an image forming apparatus that supports a high speed with a simple configuration, toner leakage can be prevented and stable sealing performance can be exhibited over a long period of time.

  Further, the step portion is arranged outside the inner end portion of the magnetic seal member in the longitudinal direction of the developing roller. Accordingly, the toner is physically blocked by the step portion outside the inner end portion of the magnetic seal member, and the toner does not move to an area where the magnetic binding force of the magnetic seal member is weak. It is possible to effectively prevent outflow.

  Further, the tape member is formed with a tapered portion for guiding the toner to the developing region side. Therefore, when the developing roller rotates, the magnetic toner that passes through the magnetic seal member and flows out of the developing area is guided to the developing area side by the taper portion, so that the toner flows out of the developing area. Can be effectively prevented. As a result, even in an image forming apparatus that supports high speed, it is possible to effectively prevent toner leakage and to exhibit stable sealing performance over a long period of time.

  Further, the tapered portion is arranged outside the inner end portion of the magnetic seal member in the longitudinal direction of the developing roller. Accordingly, the toner is physically blocked by the tapered portion outside the inner end portion of the magnetic seal member, and the toner does not move to an area where the magnetic binding force of the magnetic seal member is weak. It is possible to effectively prevent outflow.

  In addition, according to the image forming apparatus of the present invention, since any one of the above-described developing devices is provided, the same effect as any of the above-described developing devices can be obtained.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus 1 includes a sheet feeding unit 2 disposed at a lower portion of the image forming apparatus main body 1a, and a sheet conveying unit disposed on the side and above the sheet feeding unit 2. 3, an image forming unit 4 disposed above the sheet conveying unit 3, a fixing unit 5 disposed on the discharge side of the image forming unit 4, the image forming unit 4, and the fixing unit 5 is provided with an image reading unit 6 disposed above 5.

  The paper feed unit 2 includes a plurality (four in this embodiment) of paper feed cassettes 7 in which paper 9 is stored. The paper 9 is sent from the selected paper feed cassette 7 to the paper transport unit 3, and the paper 9 is surely fed to the paper transport unit 3 one by one. These four paper feed cassettes 7 are configured to be detachable from the image forming apparatus main body 1a.

  The paper 9 fed to the paper transport unit 3 is transported toward the image forming unit 4 via the paper supply path 10. The image forming unit 4 forms a predetermined toner image on the paper 9 by an electrophotographic process, and is an image end holder that is rotatably supported in a predetermined direction (the arrow direction in the figure). A photoconductor 11, and a charging device 12, an exposure device 13, a developing device 14, a transfer device 15, a cleaning device 16, and a charge removal device 17 are provided around the photoconductor 11 along the rotation direction.

  The charging device 12 includes a charging wire to which a high voltage is applied. By applying a predetermined potential to the surface of the photoconductor 11 by corona discharge from the charging wire, the surface of the photoconductor 11 is uniformly charged. It is done. The exposure device 13 irradiates the photoconductor 11 with light based on the image data of the original read by the image reading unit 6, whereby the surface potential of the photoconductor 11 is selectively attenuated, and this photosensitivity is detected. An electrostatic latent image is formed on the surface of the body 11. Next, the developing device 14 attaches toner to the electrostatic latent image to form a toner image on the surface of the photoconductor 11, and the transfer device 15 transfers the toner image on the surface of the photoconductor 11 to the photoconductor 11. The image is transferred to a sheet 9 supplied between the apparatus 15 and the apparatus 15.

  The sheet 9 on which the toner image is transferred is conveyed from the image forming unit 4 toward the fixing unit 5. The fixing unit 5 is disposed on the downstream side of the image forming unit 4 in the sheet conveying direction, and the sheet 9 on which the toner image is transferred in the image forming unit 4 includes a heating roller 18 provided in the fixing unit 5, and The toner image is fixed on the sheet 9 by being sandwiched and heated by the pressure roller 19 pressed against the heating roller 18. Next, the sheet 9 on which the image is formed in the fixing unit 5 from the image forming unit 4 is discharged onto the discharge tray 21 by the discharge roller pair 20. On the other hand, after the transfer, the toner remaining on the surface of the photoconductor 11 is removed by the cleaning device 16, and the residual charge on the surface of the photoconductor 11 is removed by the static eliminator 17. Then, the photoreceptor 11 is charged again by the charging device 12, and image formation is performed in the same manner.

  Next, the developing device will be described with reference to the drawings. FIG. 2 is a cross-sectional view showing a developing device in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a front view of the developing roller provided in the developing device shown in FIG. It is.

  As shown in FIG. 2, the developing device 14 according to this embodiment includes a developing container 22 that stores toner, and a pair of mixers 23 and 24 disposed in the developing container 22. Further, a fixed magnet roller 25 having a plurality of magnetic poles disposed on the drum opening side of the developing container 22 and containing the fixed magnet roller 25 and guiding the stored toner onto the surface of the photoreceptor 11. A developing roller (or toner carrying roller) 27 including a nonmagnetic developing sleeve 26 that is rotatably supported is provided. Further, it is composed of a plate-like magnetic body, and is disposed in the vicinity of the developing sleeve 26, and is suspended in the upper surface of the developing sleeve 26, and the longitudinal direction of the developing roller 27 (the arrow shown in FIG. 3). A magnetic seal member 29 disposed at the end of the X direction) and a developing bias 40 applied between the developing roller 27 and the photosensitive member 11 are provided.

  A toner replenishing hole H is opened on the upper surface of the developing container 22 above the mixer 23 so that toner from a toner cartridge (not shown) can be input. The charged toner is sufficiently stirred by the pair of mixers 23 and 24 and guided to the developing sleeve 26. The toner guided to the developing sleeve 26 is carried on the developing sleeve 26 using the magnetic force of the fixed magnet roller 25, and the toner is disposed in the vicinity of the developing sleeve 26 and acts as a toner layer thickness regulating member. The thickness is regulated by the magnetic blade 28. Thereafter, the toner carried on the developing sleeve 26 is guided to the developing position, that is, on the surface of the photoreceptor 11 by the developing roller 27.

  The developing sleeve 26 is set to a predetermined peripheral speed (in this embodiment, for example, 430 mm / sec), but the developing sleeve 26 is in the same direction between the drum and the sleeve with respect to the rotation direction of the photosensitive member 11. It is set to rotate (see FIG. 2). The developing sleeve 26 is disposed at a predetermined distance from the photoconductor 11. The developing bias 40 is applied with a low electric field developing bias in which a direct current component DC and an alternating current component AC are superimposed, and image density is adjusted by controlling the AC oscillation frequency. At the time of non-development, the DC component DC is cut off and only the AC component AC is applied to remove the reverse polarity toner.

  Further, the magnetic seal member 29 is for preventing the toner from leaking from the end portion in the longitudinal direction of the developing sleeve 26. As shown in FIG. The sleeve 26 is disposed at a constant interval with respect to the outer peripheral surface. In addition, the said space | interval can be set to 0.3-1 mm, for example.

  The magnetic seal member 29 is formed of a magnetic material (for example, a magnet or a ferromagnetic material), and the toner that moves so as to flow out from the end of the developing sleeve 26 is fixed to the fixed magnet roller 25. It is restrained by the magnetic field formed in the gap with the magnetic seal member 29. Then, along each magnetic force line formed by the magnetic pole of the fixed magnet roller 25 and the magnetic pole of the magnetic seal member 29, the magnetic brush due to the rising of the toner at the inner end portion 29a where the magnetic binding force of the magnetic seal member 29 concentrates. Is formed. The magnetic brush fills the gap between the outer peripheral surface of the developing sleeve 26 and the surface of the magnetic seal member 29, thereby preventing the toner from flowing out of the developing region. The magnetic seal member 29 is disposed on the opposite side of the photoconductor 11 via the developing sleeve 26 as shown in FIGS.

  In this configuration, the present embodiment is characterized in that a step portion is provided on the surface of the developing roller. In the following, this feature and the effects achieved by this feature will be described in detail with reference to the drawings. FIG. 4 is a partially enlarged view for explaining a step portion provided on the developing roller in the developing device according to the embodiment of the present invention.

  As shown in FIGS. 3 and 4, in the present embodiment, the developing roller 27 is set such that the outer diameter Y of the end 27 b of the developing roller 27 is larger than the outer diameter Z of the main body 27 a of the developing roller 27. 27 is provided with a stepped portion 30. That is, the developing roller 27 is provided with a stepped portion 30, and the developing roller 27 is divided into a main body portion 27a and an end portion 27b with the stepped portion 30 as a boundary. And the outer diameter Y of the edge part 27b is set larger than the outer diameter Z of the main-body part 27a.

  As described above, in the high-speed machine, the force for pushing the magnetic toner to the outside increases, so that the magnetic toner easily passes through the magnetic seal member 29 and easily leaks out of the development area. However, in this embodiment, the step portion 30 is provided on the developing roller 27 by setting the outer diameter Y of the end portion 27b of the developing roller 27 to be larger than the outer diameter Z of the main body portion 27a of the developing roller 27. It is said. Therefore, the magnetic toner that passes through the magnetic seal member 29 and is about to flow out of the developing area is physically blocked by the stepped portion 30, thereby preventing the magnetic toner from flowing out of the developing area. Is possible. As a result, even in an image forming apparatus that supports high speed, it is possible to prevent toner leakage and to exhibit stable sealing performance over a long period of time.

  In the present embodiment, as shown in FIG. 4, the stepped portion 30 is arranged outside the inner end portion 29 a of the magnetic seal member 29 in the longitudinal direction X of the developing roller 27. In general, in the magnetic seal member 29, the magnetic restraint force is concentrated on the inner end portion 29a, and the magnetic restraint force is weak in the region outside the inner end portion 29a (that is, outside the development region). However, with this configuration, the magnetic toner is physically blocked by the step portion 30 outside the inner end portion 29a of the magnetic seal member 29, and the magnetic toner does not move to a region where the magnetic binding force is weak. It is possible to effectively prevent the toner from flowing out of the development area.

  The difference between the outer diameter Y of the end portion 27b and the outer diameter Z of the main body portion 27a is a value within a range in which the magnetic toner can be prevented from slipping out of the magnetic seal member 29 and leaking out of the developing area. More specifically, the difference between the surface 27c of the main body portion 27a and the surface 27d of the end portion 27b (that is, the thickness of the stepped portion 30) may be set to be 0.1 mm or more. It ’s fine. However, if the thickness of the stepped portion 30 is too large, the magnetic seal member 29 and the stepped portion 30 come into contact with each other. Therefore, in the present embodiment, for example, the outer peripheral surface of the developing sleeve 26 and the magnetic seal member 29 Is set to 0.3 mm, the thickness of the stepped portion 30 is preferably 0.1 to 0.2 mm. Therefore, in this case, when the outer diameter Z of the main body portion 27a is set to 25 mm, the outer diameter Y of the end portion 27b can be set to 25.2 mm.

  In this embodiment, the outer diameter of the end portion 27b of the developing roller 27 is made larger than the outer diameter Z of the main body portion 27a of the developing roller 27 by a simple configuration in which a tape member is wound around the end portion 27b of the developing roller 27. And a stepped portion 30 can be provided on the developing roller 27. In the following, this feature and the effects achieved by this feature will be described in detail with reference to the drawings. FIG. 5 is a schematic view for explaining a tape member provided at the end of the developing roller in the developing device according to the embodiment of the present invention, and FIG. 6 explains winding of the tape member shown in FIG. FIG.

  As the tape member 31, for example, a cellophane tape or a Teflon (registered trademark) tape can be used. As shown in FIG. 5, the tape member 31 has a taper for guiding magnetic toner to the developing region side. A portion 34 is formed. The length A of the tape member 31 is set to the length of the outer periphery of the developing roller 27 (that is, the outer diameter Z × π of the main body 27a of the developing roller 27) +1 mm. This is because if the length A is set to the same length as the outer periphery of the developing roller 27, when the tape member 31 is wound and used, the magnetic toner is transferred to the upper end 32 (or the tape member 31). This is to avoid the inconvenience because there is a risk of being caught by the lower end 33). Also, the thickness of the tape member 31 prevents the magnetic toner from passing through the magnetic seal member 29 and leaking out of the developing area, and avoids contact between the magnetic seal member 29 and the stepped portion 30. The thickness that can be formed, for example, 0.1 mm is set.

  When winding the tape member 31 around the developing roller 27, as shown in FIG. 6, first, the outer end 35 of the tape member 31 is aligned with the surface 27c of the developing roller 27, and then the lower end of the tape member 31 is placed. The portion 33 is wound around the developing roller 27. At this time, as shown in FIG. 6, the tape member 31 is wound around such that the tapered portion 34 is disposed on the inner side (that is, on the developing region side) in the longitudinal direction X of the developing roller 27. Yes. A state in which the tape member 31 is wound around the end portion 27b of the developing roller 27 is shown in FIG.

  By winding the tape member 31 as described above, the taper portion 34 serves as a spiral when the developing roller 27 rotates. Therefore, the magnetic toner that tries to flow out of the developing area by passing through the magnetic seal member 29 by the tapered portion 34 is guided to the developing area, so that the magnetic toner flows out of the developing area. Can be effectively prevented. Further, as shown in FIG. 7, since the tapered portion 34 also serves as a stepped portion 30, the magnetic toner is physically blocked by the tapered portion 34, so that the magnetic toner is moved out of the development area. It is possible to prevent the leakage. As a result, even in an image forming apparatus that supports high speed, it is possible to effectively prevent toner leakage and to exhibit stable sealing performance over a long period of time.

  Further, as shown in FIG. 7, the tapered portion 34 that also serves as the stepped portion 30 is arranged outside the inner end portion 29 a of the magnetic seal member 29 in the longitudinal direction X of the developing roller 27. Accordingly, the magnetic toner is physically blocked by the taper portion 34 outside the inner end portion 29a of the magnetic seal member 29, and the magnetic toner does not move to an area where the magnetic binding force is weak. It is possible to effectively prevent outflow.

  5 to 7, the case where the tape member 31 is wound once around the developing roller 27 has been described. However, the tape member may be double wound around the developing roller. . In the following, this feature and the effects achieved by this feature will be described in detail with reference to the drawings. FIG. 8 is a schematic view for explaining a double-winding tape member provided at the end of the developing roller in the developing device according to the embodiment of the present invention, and FIG. 9 is a tape member shown in FIG. It is the elements on larger scale for demonstrating winding of No ..

  As the tape member 36 shown in FIG. 8, for example, a cellophane tape or a Teflon (registered trademark) tape can be used as in the tape member 31 shown in FIG. Further, as shown in FIG. 8, the tape member 36 is formed by connecting a tape member 37 having a substantially rectangular shape to the lower end portion 33 of the tape member 31 having the tapered portion 34 described above. is there. The length B of the tape member 36 is set to the length of the outer periphery of the developing roller 27 (that is, the outer diameter Z × π of the main body 27a of the developing roller 27) × 2 + 1 mm. The length B is set in this way for the same reason as in the case of the tape member 31 described above. Also, the thickness of the tape member 36 is set to 0.1 mm, for example, for the same reason as in the case of the tape member 31 described above.

  When winding the tape member 36 around the developing roller 27, as shown in FIG. 9, first, the outer end 38 of the tape member 36 is aligned with the surface 27c of the developing roller 27, and then the lower end of the tape member 36 is placed. The tape member 37 is wound around the developing roller 27 from the portion 39. Next, the tape member 31 is wound around the developing roller 27 so as to overlap the tape member 37. At this time, as in the case of FIG. 6 described above, the tape member 31 is wound around such that the tapered portion 34 is disposed inside in the longitudinal direction X of the developing roller 27. FIG. 10 shows a state in which the tape member 36 is wound around the end portion 27b of the developing roller 27.

  By winding such a tape member 36, the magnetic toner that passes through the magnetic seal member 29 and flows out of the developing region is physically caused by the inner end 41 of the tape member 36 that functions as the stepped portion 30. Therefore, the magnetic toner can be prevented from flowing out of the development area. Similarly to the case described with reference to FIG. 7, when the developing roller 27 rotates, the taper portion 34 plays a role of a spiral, and the taper portion 34 passes through the magnetic seal member 29 and is out of the developing area. Since the magnetic toner that is about to flow out is guided to the development area side, it is possible to effectively prevent the magnetic toner from flowing out of the development area. Furthermore, since the taper portion 34 also serves as the step portion 30, the magnetic toner is physically blocked by the taper portion 34, so that the magnetic toner is prevented from flowing out of the development area. Is possible. As a result, even in an image forming apparatus that supports high speed, it is possible to prevent toner leakage more effectively and to exhibit stable sealing performance over a long period of time.

  Also in this case, as shown in FIG. 10, the inner end portion 41 of the tape member 36 that functions as the step portion 30 and the taper portion 34 that also serves as the step portion 30 are magnetic in the longitudinal direction X of the developing roller 27. The body seal member 29 is disposed outside the inner end portion 29a. Therefore, the magnetic toner is physically blocked by the inner end 41 and the tapered portion 34 functioning as the stepped portion 30 outside the inner end 29a, and the magnetic toner does not move to a region where the magnetic binding force is weak. It is possible to effectively prevent the toner from flowing out of the development area.

  In addition, the said embodiment is only an explanatory example, The scope of the present invention is not limited to the said embodiment, Based on the meaning of this invention, the shape, dimension, material, etc. of each structural article are changed. It is possible that they are not excluded from the scope of the present invention.

  For example, if the magnetic toner can be prevented from slipping out of the magnetic seal member 29 and leaking out of the development area, and the contact between the magnetic seal member 29 and the stepped portion 30 can be avoided, the tape member can be removed. It is good also as a structure which makes more than triple winding with respect to a developing roller.

  In the above embodiment, a digital copying machine is shown as an example of the image forming apparatus. However, it goes without saying that other image forming apparatuses such as a facsimile and a printer may be used.

  The present invention relates to a developing device that performs development by electrophotographic development using magnetic toner, and more particularly, a developing device that prevents scattering of magnetic toner outside the developing region, and image formation provided with the developing device. Relates to the device.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a developing device in an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a front view when a developing roller provided in the developing device shown in FIG. 2 is viewed from the photosensitive member side. FIG. 6 is a partially enlarged view for explaining a step portion provided on the developing roller in the developing device according to the embodiment of the present invention. It is the schematic for demonstrating the tape member provided in the edge part of the developing roller in the developing device which concerns on embodiment of this invention. It is the elements on larger scale for demonstrating winding of the tape member shown in FIG. FIG. 6 is a partially enlarged view showing a state where the tape member shown in FIG. 5 is wound around the end portion of the developing roller. It is the schematic for demonstrating the tape member for double winding provided in the edge part of the developing roller in the image development apparatus concerning embodiment of this invention. It is the elements on larger scale for demonstrating winding of the tape member shown in FIG. It is the elements on larger scale which show the state which wound the tape member shown in FIG. 8 around the edge part of the developing roller.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Paper feed part, 3 ... Paper conveyance part, 4 ... Image formation part, 5 ... Fixing part, 6 ... Image reading part, 11 ... Photoconductor, 14 ... Developing apparatus, 25 ... Fixed magnet roller 26 ... developing sleeve, 27 ... developing roller, 27a ... developing roller body, 27b ... developing roller end, 27c ... developing roller body surface, 27d ... developing roller end surface, 29 ... magnetic material Seal member, 29a ... Inner end of magnetic seal member, 30 ... Stepped portion, 31 ... Tape member, 36 ... Tape member, 37 ... Tape member, 34 ... Tapered portion, 41 ... Inner end of tape member, X ... The longitudinal direction of the developing roller, Y: the outer diameter of the end of the developing roller, Z: the outer diameter of the main body of the developing roller

Claims (3)

A developing roller that includes a fixed magnet roller having a plurality of magnetic poles and that is rotatably supported to guide toner onto the surface of the photosensitive member, and a developing sleeve at a longitudinal end of the developing sleeve. In a developing device comprising a magnetic seal member disposed at a distance from the outer peripheral surface,
A tape member is wound around the outer peripheral surface of the longitudinal end of the developing sleeve;
The tape member includes a first tape portion wound around the outer peripheral surface of the developing sleeve and a second tape portion wound around the outer peripheral surface of the first tape portion;
The step portion is constituted by a first step portion formed by the first tape portion and a second step portion formed by the second tape portion;
The second step portion is provided outside the first step portion in the longitudinal direction of the developing sleeve;
A taper portion is provided on the toner carrying side of the developing sleeve of the second tape portion;
The tapered portion is inclined from the inner side to the outer side in the longitudinal direction of the developing sleeve as it goes from the rear side to the front side in the rotation direction of the developing sleeve;
The end of the first step portion located on the toner carrying side of the developing sleeve is defined as a first inner end portion, and the end of the second step portion located on the toner carrying side of the developing sleeve is defined as a second inner side. The end of the magnetic seal member located on the toner carrying side of the developing sleeve is used as an inner end of the seal, and the end of the magnetic seal member located on the side opposite to the inner end of the seal is used as an end. As a seal outer end portion, the first inner end portion and the second inner end portion are located between a position corresponding to the seal inner end portion and a position corresponding to the seal outer end portion in the longitudinal direction of the developing sleeve. What is provided
A developing device. The developing device according to claim 1, wherein the tape member is a cellophane tape or a Teflon (registered trademark) tape. An image forming apparatus comprising the developing device according to claim 1 .

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