JP2014228666A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent toner from being melt-stuck and aggregated onto the rotary shaft of a stirring member by properly radiating heat caused by the friction between the rotary shaft of the stirring member rotating in a developing device and a seal member to the outside.SOLUTION: In a developing device 20 including a developing roller conveying a developer in a device body 21 to a photoreceptor 11 and a stirring member 27 rotating in the device body 21, to stir the developer in the device body 21, a rotary shaft 27a in the stirring member 27 is freely rotatably supported by a bearing part 31, a seal member 32 through which the rotary shaft passes is provided on the device body side of the bearing part 31, a heat transfer member 40 having high heat conductivity is arranged so as to surround the vicinity of the bearing part 31, and a heat radiation member 41 radiating the heat from the heat transfer member 40 is provided toward the outside of the device body 21.

Description

  The present invention relates to a developing device used for developing an electrostatic latent image formed on an image carrier in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine of these, and particularly, in the developing device. In the stirring member that rotates and stirs the developer, the toner on the rotating shaft near the bearing portion can be prevented from being fused and aggregated.

  Conventionally, in an image forming apparatus such as a copying machine or a printer, toner is supplied from a developing device to an electrostatic latent image formed on an image carrier such as a photoconductor, and the electrostatic latent image formed on the image carrier. The image is developed.

  In these developing devices, the developer is stirred by a rotating stirring member and the developer is supplied to the developing roller. The developing roller guides the developer to a position facing the image carrier, and the developing roller. The toner is supplied from the toner to the image carrier to perform development. Further, when the toner is reduced as a result of the development as described above, the toner is supplied to the developing device through a toner supply port provided in the developing device.

  In the developing device as described above, in order to prevent the toner from entering the bearing portion of the rotating stirring member and the toner from leaking to the outside, a ring shape is formed on the inner surface side inside the bearing. A resin sealing member is provided.

  However, when the stirring member is rotated in a state where the seal member is provided on the inner surface side inside the bearing portion in this way, the rotation shaft of the stirring member is caused by frictional heat between the rotation shaft of the stirring member and the seal member. The toner is fused to the rotating shaft of the heated stirrer member and the aggregated toner falls off the stirrer member and enters the developer, thereby causing streak noise or the like in the formed image. There was a problem.

  In particular, in a two-component development type developing device using toner and carrier as a developer, in order to improve development speed when carrying out development while mixing and stirring toner and carrier by the stirring member, Increasing the rotation speed of the stirring member is performed. When the rotation speed of the stirring member is increased in this way, the frictional heat between the rotation shaft of the stirring member and the seal member increases, and replenishment from the toner replenishment port without developer on the rotation shaft of the stirring member. When the toner thus introduced is guided to the rotating shaft, there is a problem that the toner is easily fused and aggregated to the rotating shaft of the stirring member.

  For this reason, conventionally, as disclosed in Patent Document 1, a stirring gear that rotates a stirring member and a developing gear that forms a gear train and a gear train to rotate the developing member are accommodated, and a stirring rotating shaft is accommodated. And the development rotating shaft are rotatably supported, and air is taken in from the intake port into an accommodation box formed with an intake port for taking in air and an exhaust port for discharging the taken-in air. A heat generating stirring shaft, a developing rotating shaft, a stirring gear, and a developing gear that are cooled are proposed.

  However, in the above configuration, the toner from the developing device is caught in the driving unit of the stirring rotation shaft, the developing rotation shaft, the stirring gear, and the developing gear, and the toner adheres to the driving unit and uneven driving occurs. There was a problem that the toner was scattered and the inside of the machine was dirty.

  Further, in Patent Document 2, a seal member that penetrates the rotation shaft is provided on the inner surface side of the device main body of the bearing portion, and at least one end portion of the rotation shaft that protrudes outside the device main body from a position in contact with the seal member. Is configured with a material with high thermal conductivity, and is configured so that the end of the rotating shaft that is configured with a material with high thermal conductivity and protrudes outside the apparatus body is in contact with a heat radiating member with high thermal conductivity, Proposals have been made to appropriately radiate heat to the outside through a heat radiating member.

  In the configuration described above, even when heat is generated due to friction between the rotating shaft of the stirring member and the seal member, this heat is transmitted from the end of the rotating shaft made of a material having high thermal conductivity to the heat radiating member, and this heat dissipation. Heat is appropriately radiated to the outside through the member. As a result, toner fusion can be prevented.

  However, in this configuration, heat is transferred from the vicinity of the bearing portion where heat generation is intense due to friction to the end of the rotating shaft, and this heat is dissipated from the heat radiating member. Compared with the case where heat is directly radiated from the vicinity of the heat sink, the efficiency of heat radiation is deteriorated, and it is required to further improve the heat radiation efficiency.

JP 2012-3059 A JP 2008-257075 A

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in a developing device used in an image forming apparatus such as a copying machine or a printer, and the rotation of a stirring member that rotates in the developing device as described above. Even when heat is generated due to friction between the shaft and the seal member, the heat is appropriately dissipated to the outside, and the toner is appropriately prevented from being fused and aggregated to the rotating shaft of the stirring member. Is an issue.

  In the developing device according to the present invention, in order to solve the above-described problems, a developing roller that conveys the developer in the apparatus main body to the photosensitive member, and the developer in the apparatus main body that rotates in the apparatus main body are agitated. In the developing device provided with the stirring member, the rotation shaft of the stirring member is rotatably supported by the bearing portion, and the seal is formed by penetrating the rotation shaft on the device main body side of the bearing portion. A heat transfer member having a high thermal conductivity is disposed so as to surround the vicinity of the bearing portion, and a heat dissipation member for radiating the heat transmitted from the heat transfer member is provided toward the outside of the apparatus main body. The heat generated in the bearing portion during driving is radiated from the heat radiating member through the heat transfer member.

  Here, in the developing device, the heat dissipating member is disposed at a position away from the developing roller and does not guide air to the developing roller, and cooling air from a cooling fan is applied to the heat dissipating member. It is preferable that it is comprised so that it may be.

  And the said bearing part can be attached to the housing of an apparatus main body, and it can comprise so that the said heat-transfer member may be formed with a resin material with better heat conductivity than a housing.

  Further, the heat transfer member and the heat radiating member may be integrally formed, and the heat radiating member is preferably formed of a material having better thermal conductivity than the heat transfer member.

  In the image forming apparatus of the present invention, the developing device as described above is used.

  In the image forming apparatus of the present invention, it is preferable that a plurality of developing devices are arranged in a row, and the heat radiating members in the plurality of developing devices are arranged so as to be shifted in a direction crossing the direction in which the cooling air flows. .

  In the image forming apparatus of the present invention, the heat dissipating member is provided with fins, a plurality of developing devices are arranged in a line, and the heat dissipating member is enlarged or dissipated as the distance from the cooling fan increases. The number of fins provided on the member can be increased. Further, the size of the heat radiating member or the number of fins provided on the heat radiating member can be changed depending on the difference in the aggregation temperature of the toner accommodated in each developing device.

  According to the present invention, since the heat transfer member having high thermal conductivity is disposed in the vicinity of the bearing portion, the heat stored in the vicinity of the bearing portion is absorbed by the heat transfer member and absorbed by the heat transfer member. The generated heat is transferred to the heat radiating portion, radiated from the heat radiating member, and temperature rise in the vicinity of the bearing portion can be suppressed.

1 is a schematic explanatory diagram illustrating an internal structure of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic explanatory view showing an imaging cartridge using a developing device according to an embodiment of the present invention. It is a schematic explanatory drawing which shows the structure centering on the bearing part of the developing device which concerns on one Embodiment of this invention. It is a schematic explanatory drawing which shows the structure of the developing device which concerns on one Embodiment of this invention. It is the schematic explanatory drawing made into the cross section by the E-E 'line of FIG. FIG. 2 is a perspective view showing a main part of a developing device according to an embodiment of the present invention. It is a perspective view which shows the heat-transfer member and heat-radiation member which are used for the image development apparatus concerning one Embodiment of this invention. It is a perspective view which shows the heat-transfer member and heat-radiation member which are used for the image development apparatus concerning one Embodiment of this invention. 1 is a schematic cross-sectional view showing an image forming apparatus in which an imaging cartridge using a developing device according to an embodiment of the present invention is arranged in tandem. FIG. 3 is a schematic plan view showing a state in which an imaging cartridge using the developing device according to the embodiment of the present invention is arranged in tandem and the position of a heat radiating member provided in the developing device is slid. FIG. 3 is a schematic plan view showing a state where an imaging cartridge using the developing device according to the embodiment of the present invention is arranged in tandem and the size of a heat radiating member provided in the developing device is changed. It is a schematic plan view which shows the state performed.

  Next, an image forming apparatus and a developing apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Note that the image forming apparatus and the developing apparatus according to the present invention are not limited to those shown in the following embodiments, and can be appropriately modified and implemented without departing from the scope of the invention.

  In the image forming apparatus of this embodiment, as shown in FIG. 1, four imaging cartridges 10 </ b> A to 10 </ b> D are mounted in the image forming apparatus 1.

  Here, in each of the imaging cartridges 10 </ b> A to 10 </ b> D, toner is supplied to the photoreceptor 11, the charging device 12 that charges the surface of the photoreceptor 11, and the electrostatic latent image formed on the surface of the photoreceptor 11. A developing device 20 that forms a toner image, and a cleaning device 14 that removes toner remaining after the toner image formed on the surface of the photoconductor 11 is transferred to the intermediate transfer belt 2 from the surface of the photoconductor 11. Is provided. The surface of the charged photoconductor 11 is exposed according to image information from the exposure device 50, and an electrostatic latent image is formed on the surface of the photoconductor 11.

  In the image forming apparatus according to this embodiment, when full-color image formation is performed, each developing device 20 in each of the imaging cartridges 10A to 10D has different colors of black, yellow, magenta, and cyan. The toner is accommodated, and a toner image of each color is formed on the surface of each photoconductor 11 in each of the imaging cartridges 10A to 10D.

  Next, the toner images of each color formed on the surface of the photoreceptor 11 in each of the imaging cartridges 10 </ b> A to 10 </ b> D in this way are sequentially transferred to the intermediate transfer belt 2, and full color toner is transferred onto the intermediate transfer belt 2. Form an image.

  On the other hand, the recording medium S is fed by the paper feed roller 3, and this recording medium S is guided between the intermediate transfer belt 2 and the transfer roller 5 at an appropriate timing by the timing roller 4, and on the intermediate transfer belt 2. The formed full-color toner image is transferred to the recording medium S, while the toner remaining on the intermediate transfer belt 2 without being transferred to the recording medium S is removed from the intermediate transfer belt 2 by the second cleaning device 6. Let

  Then, the recording medium S on which the full-color toner image is transferred as described above is guided to the fixing device 7, and after fixing the full-color toner image on the recording medium S, the recording medium S is discharged by the paper discharge roller 8. The paper is discharged.

  In the image forming apparatus 1 of this embodiment, the cooling fan 30 is provided below the second cleaning device 6 to cool the imaging cartridges 10A to 10D.

  The image forming apparatus is not limited to the one described above, and although not shown in the drawing, a rotary developing device holding a plurality of developing devices is rotated to sequentially guide each developing device to the photoreceptor. Thus, a full-color image forming apparatus configured to perform full-color image formation or an image forming apparatus performing black-and-white image formation may be used.

  Next, the imaging cartridges 10A to 10D in this embodiment will be specifically described. As shown in FIG. 2, the imaging cartridges 10 </ b> A to 10 </ b> D are composed of a developing device 20 and a photoreceptor unit 110.

  The photoconductor unit 110 includes a photoconductor 11, a charging roller as a charging device 12, and a cleaning device 14 including a cleaning blade.

  In the developing device 20, a developer containing toner and carrier is used. Here, in the developing device 20, as shown in FIG. 2, a developing roller 22 having a magnet roller 22 a provided therein is provided so as to face the photoconductor 11 with a required interval.

  Moreover, in this developing device 20, as shown in FIGS. 2-4, the 1st conveyance part 23 which conveys the said developer along the said developing roller 22 is provided in the apparatus main body 21, A first stirring member 24 provided with a screw-like blade member 24b that transports the developer while mixing and stirring around the rotation shaft 24a is provided in the first transport unit 23. And the 2nd conveyance part 26 which conveys the 1st conveyance part 23 and the above-mentioned developer in the reverse direction via partition 25 below this 1st conveyance part 23 is provided, and in this 2nd conveyance part 26, A second stirring member 27 provided with a screw-like blade member 27b that transports the developer while mixing and stirring is provided around the rotating shaft 27a.

  Furthermore, a circulation port 25a for communicating the first transport unit 23 and the second transport unit 26 is provided at an end of a partition wall 25 provided between the first transport unit 23 and the second transport unit 26. The developer is circulated between the first transport unit 23 and the second transport unit 26 through the circulation ports 25a.

  Further, a toner supply port (not shown) for supplying toner contained in a toner cartridge (not shown) into the apparatus main body 21 of the developing device 20 is provided on the upper surface of the end portion of the first transport unit 23. It has been.

  In the developing device 20, the first stirring member 24 rotates the first stirring member 24 provided in the first transport unit 23 to transport the developer while mixing and stirring the developer roller. The developer is supplied to 22, and the amount of developer conveyed is regulated by the regulating member 29 while the developer thus fed is conveyed to the position facing the photoconductor 11 by the developing roller 22. ing. Then, the developer whose amount is regulated in this way is guided to the position facing the photoconductor 11 by the developing roller 22, and the toner in the developer is supplied to the photoconductor 11, so that the electrostatic formed on the photoconductor 11. The latent image is developed.

  Note that a dust prevention cover 20 f for suppressing dust toner generated when the developing roller 22 rotates is provided on the duct 20 e on the upper side of the developing roller 22, that is, on the intermediate transfer belt 2 side.

  Further, when the toner concentration in the developer is reduced as a result of the development as described above, the toner contained in the toner cartridge is supplied into the apparatus main body 21 through the toner supply port.

  Here, in providing the first stirring member 24 and the second stirring member 27 in the first transporting portion 23 and the second transporting portion 26, the rotation shafts of the first stirring member 24 and the second stirring member 27 are provided. One end portions of 24 a and 27 a are rotatably supported by bearing portions 31 and 31, respectively, and protrude from the inner wall 35 of the apparatus main body 21 to the outside. Further, a seal member 32 through which the rotary shafts 24 a and 27 a are penetrated is provided on the inner wall 35 side of the apparatus main body 21 of the bearing portion 31. The bearing portions 31 and 31 are attached to the housing 21 a of the apparatus main body 21. Although not shown, the other end portions of the rotary shafts 24a and 27a are also rotatably supported by the bearing portions.

  Stirring gears 24g and 27g are attached to the rotating shafts 24a and 27a, respectively, and a gear 24h that engages with a developing gear 24i that rotates the developing roller 22 is attached to the rotating shaft 27a. , 24h constitute a gear train G, and the first stirring member 24, the second stirring member 27, and the developing roller 22 are driven to rotate.

  In addition, a reversely wound screw 27d and a disk 27d are provided at the end of the second stirring member 27 so that no pressure is directly applied to the inner wall 35 and the bearing 31 side. However, a part of the developer sent to the blade member 27b gets over the reversely wound screw 27d and the disk 27d and enters the bearing portion 31.

  The bearing portions 31, 31 are arranged at a predetermined distance from the inner wall 35 at the end of the developer storage portion, and the developer that has entered the space 36 is in front of the bearing portions 31, 31. The seal member 32 provided is reached.

  The seal member 32 is made of a ring-shaped rubber-based material, and due to friction with the rotation shafts 24a and 27a, the rotation shafts 24a and 27a in the vicinity of the bearing portions 31 and 31 and the bearing portions 31 and 31 are hotter than the surroundings. It becomes. The temperature increases as the number of rotations of the rotary shafts 24a and 27a increases and may rise to near the melting temperature of the developer to solidify the developer near the bearing portions 31 and 31.

  Therefore, in this embodiment, as shown in FIGS. 4 to 6, the heat conductive material is surrounded so as to surround the vicinity of the bearing portion of the housing 21 a to which the bearing portions 31 and 31 that support the rotating shafts 24 a and 27 b are attached. A high heat transfer member 40 is disposed. The contact surface 40a on the side facing the housing 21a of the heat transfer member 40 is formed so as to follow the shape of the housing 21a. Further, a heat radiating member 41 in which a large number of fins 41 f for radiating heat from the heat transfer member 40 is formed is connected to the heat transfer member 40.

  Here, when heat is generated by friction with the seal members 32 and 32 as the rotary shafts 24a and 27a rotate, the generated heat is transferred to the bearing portions 31 and 31, respectively. Since the heat transfer member 40 having high heat conductivity is disposed in the vicinity of the bearing portions 31 and 31 as described above, heat in the bearing portions 31 and 31 and the housing 21a is transferred to the heat transfer member 40. Be heated. Further, the heat transferred to the heat transfer member 40 in this way is connected to the heat transfer member 40 and transferred to the heat radiating member 41, and this heat is radiated from the fins 41 f so as to be near the bearing portions 31 and 31. An increase in temperature is suppressed.

  Here, the heat dissipating member 41 is arranged at a position away from the developing roller 22 and the air is not guided to the developing roller 22, and dust is generated when cooling air is blown onto the heat dissipating member 41. Therefore, the bearing portions 31 and 31 and the vicinity thereof can be efficiently cooled.

  The heat transfer member 40 has better heat conductivity than the housing 21a, and is heat conductive to a resin or rubber-based soft material as a material that is easily adapted to the shape of the housing 21a where the bearing portions 31 and 31 are attached. It can form using what added the inorganic filler.

  Here, as the heat transfer member 40 and the heat radiating member 41, as shown in FIG. 7, a heat transfer member 40 and a heat radiating member 41 which are integrally formed can be used. As described above, when a member in which the heat transfer member 40 and the heat dissipation member 41 are integrally formed is used, manufacturing and the like can be easily performed.

  Moreover, as shown in FIG. 8, what separated the heat-transfer member 40 and the heat radiating member 41 can also be used. In this case, although the number of assembling steps is increased, the heat radiation effect can be enhanced by forming the heat radiation member 41 with a metal material having better heat conductivity than the heat transfer member 40.

  In order to effectively dissipate the heat from the bearing portions 31, 31, a part of the housing 21 a can be cut out and the heat transfer member 40 can be brought into direct contact with the bearing portions 31, 31. However, if a part of the housing 21a is notched, the developer may leak from this part. Therefore, in consideration of heat dissipation and dust generation, the heat transfer member 40 may be disposed through the housing 21a or directly transferred. Whether to arrange the heat member 40 may be appropriately selected depending on the application, the position of the developing device 20, and the like.

  FIG. 9 is a diagram showing the flow of cooling air in the image forming apparatus 1 in which the imaging cartridges 10A to 10D are arranged in tandem and the developing devices 20 are arranged in a line. A cooling fan 30 is provided to cool the developing device 20. The cooling fan 30 disposed in the image forming apparatus 1 sucks air into a space surrounded by the intermediate transfer belt 2 and the base 100 of the apparatus, and cools by the sucked air. The cooling air indicated by the arrow F in the figure passes through the heat radiation member 41 of each developing device 20 and is discharged by the cooling fan 30.

  By the way, when the cooling air flows in the vicinity of the developing roller 22, the toner dust generated around the developing roller 22 when the developing device 20 is driven is entrained, and the toner dust enters the driving unit of the developing device 20. Therefore, the adjacent photoreceptor unit 110 and the like are contaminated with toner, so that a flow path is formed so that air flows under the developing device 20 away from the developing roller 22 of the developing device 20. .

  The above-described air flow cannot sufficiently cool the entire developing device 20, so that there is a problem of solidification and aggregation of the developer due to a temperature rise in the heat storage section such as the bearing sections 31 and 31.

  Therefore, as in this embodiment, the heat from the high temperature portion near the bearing portions 31, 31 is transferred to the heat transfer member 40, and the position where the cooling air flows through the heat dissipation member 41 connected to the heat transfer member 40. By providing them, the bearing portions 31 and 31 and the vicinity thereof can be efficiently cooled, and the toner in the rotating shafts 24a and 27a in the vicinity of the bearing portions 31 and 31 and the bearing portions 31 and 31 is melted and aggregated and solidified. This prevents the generation of smoke by the cooling air.

  Further, in the tandem configuration as shown in FIG. 9, there is a difference in the air flow since another developing device 20 is arranged in a straight line between the distance to the cooling fan 30, that is, on the side closer to and far from the cooling fan 30. Will occur.

  For this reason, as shown in FIG. 10, the heat radiating member 41 in each developing device 20 can be configured to be shifted in a direction intersecting the direction in which the cooling air flows to prevent a decrease in the air volume far from the cooling fan 30. . Further, the heat radiating members 41 in each developing device 20 can be arranged in a staggered manner in a direction intersecting with the direction in which the cooling air flows to prevent a reduction in the air volume far from the cooling fan 30.

  Further, as shown in FIG. 11, as the distance from the cooling fan 30, the size of the heat radiating member 41 and the size of the fins 41f are changed so as to increase the shape, that is, the size of the heat radiating member 41 or increase the number of fins 41f. You may comprise. The shape can be changed not only by the distance of the cooling fan 30 but also by changing the shape of the heat radiating member 41 depending on the difference in the aggregation temperature of the toner stored in each developing device 20.

  In the developing device 20 of the above-described embodiment, the developer containing toner and carrier is circulated between the first transport unit 23 and the second transport unit 26 that are arranged in the vertical direction via the partition wall 25. However, the arrangement state of the first conveyance unit and the second conveyance unit that circulate the developer including the toner and the carrier and the type of the developer to be used are not limited to the above. For example, although not shown, the developing device is configured to circulate a developer including toner and a carrier between a first transport unit and a second transport unit that are horizontally disposed through a partition wall. Alternatively, it may be a one-component developing device in which a developer containing only a toner that does not contain a carrier is used and the developer is stirred by a stirring member.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Intermediate transfer belt 3 Feed roller 4 Timing roller 5 Transfer roller 6 Second cleaning device 7 Fixing device 8 Paper discharge roller 10A to 10D Imaging cartridge 11 Photoconductor 12 Charging device 14 Cleaning device 20 Developing device 21 Device main body 21a housing 22 developing roller 22a magnet roller 23 first transport unit 24 first stirring member 24a rotating shaft 24b blade member 26 second transport unit 27 second stirring member 27a rotating shaft 27b blade member 30 cooling fan 31 bearing unit 32 seal member 40 Heat transfer member 41 Heat dissipation member 41f Fin

Claims (9)

In the developing device provided with a developing roller that conveys the developer in the apparatus main body to the photoreceptor, and a stirring member that rotates in the apparatus main body and stirs the developer in the apparatus main body.
The rotating shaft of the agitating member is rotatably supported by the bearing portion, and a seal member penetrating the rotating shaft is provided on the apparatus main body side of the bearing portion so as to surround the vicinity of the bearing portion. A heat transfer member with high heat conductivity is disposed on the heat dissipating member, and a heat dissipating member for dissipating heat transmitted from the heat transfer member is provided to the outside of the apparatus main body. A developing device characterized in that heat is radiated from the heat radiating member via the heat transfer member.   2. The developing device according to claim 1, wherein the heat dissipating member is separated from the developing roller and is disposed at a position where air is not guided to the developing roller, and cooling air from a cooling fan is given to the heat dissipating member. A developing device.   3. The developing device according to claim 1, wherein the bearing portion is attached to a housing of the apparatus main body, and the heat transfer member is formed of a resin material having better thermal conductivity than the housing. A developing device.   4. The developing device according to claim 1, wherein the heat transfer member and the heat radiating member are integrally formed. 5.   5. The developing device according to claim 1, wherein the heat dissipating member is formed of a material having better thermal conductivity than the heat transfer member. 6.   An image forming apparatus comprising the developing device according to claim 1.   7. The image forming apparatus according to claim 6, wherein a plurality of developing devices are arranged in a row, and the heat radiating members in the plurality of developing devices are arranged so as to be shifted in a direction crossing a direction in which the cooling air flows. An image forming apparatus.   8. The image forming apparatus according to claim 6, wherein fins are provided on the heat dissipating member, a plurality of developing devices are arranged in a line, and the size of the heat dissipating member increases as the distance from the cooling fan increases. Or an image forming apparatus characterized by increasing the number of fins provided on the heat dissipating member.   9. The image forming apparatus according to claim 6, wherein the heat radiating member is provided with fins, and the heat radiating member has a fin depending on a difference in agglomeration temperature between toners accommodated in the developing devices. An image forming apparatus, wherein the size or the number of fins provided on the heat dissipation member is changed.

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