JP4930164B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and a developing device used to develop an electrostatic latent image formed on an image carrier in such an image forming apparatus. This is characterized in that the toner can be appropriately prevented from fusing and aggregating at the end of the rotating shaft of the stirring member that rotates and stirs the developer.

  2. Description of the Related Art 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 is The image is developed.

  Here, as such a developing device, there are known a two-component developing type using a toner and a carrier as a developer and a one-component developing type using only a toner without using a carrier. ing.

  In these developing devices, the developer is generally stirred by a rotating stirring member and the developer is supplied to the developing sleeve, and the developer is guided to a position facing the image carrier by the developing sleeve. Development is performed by supplying toner from the developing sleeve to the electrostatic latent image formed on the image carrier. 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.

  Further, 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 generally formed on the inner surface side of the bearing portion. A resin sealing member is provided.

  However, when the stirring member is rotated with the seal member provided on the inner surface side of the bearing portion in this manner, the frictional heat between the rotation shaft of the stirring member and the seal member causes the rotation of the rotation shaft of the stirring member. The end portion was heated, and the toner was fused and aggregated to the end portion of the rotating shaft of the stirring member thus heated. In addition, there is a problem in that the toner fused and agglomerated in this manner is dropped from the stirring member and mixed in the developer, thereby causing streak noise or the like in the formed image.

  In particular, in a two-component developing type developing device using toner and carrier as a developer, in order to improve the developing speed when the toner and carrier are conveyed while being mixed and stirred by the stirring member. In general, the rotational speed of the stirring member is increased.

  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 in particular, the end of the rotation shaft of the stirring member that contacts the seal member is made of metal. At the same time, in the state where the developer is not present at the end of the rotating shaft of the stirring member, heat is accumulated at the end of the rotating shaft of the stirring member made of metal in this way, and is supplied from the toner supply port. When the toner is guided to the end of the rotating shaft, the toner is easily fused and aggregated to the end of the rotating shaft of the stirring member.

  For this reason, conventionally, as shown in Patent Document 1, the idler shaft, the stirring blade, and the conveying blade in the developing unit are configured by heat pipes, and the frictional heat generated in these is discharged to the heat sink. Things have been proposed.

  However, when the idler shaft, the stirring blade, and the conveying blade are configured with heat pipes and a heat sink is provided separately, the costs increase and the apparatus becomes large.

  Japanese Patent Application Laid-Open No. 2004-228561 proposes a vent hole for dissipating heat in the space between the bearing member and the seal member at the end of the developing device.

  However, in this case, there is a problem that the toner may be scattered to the outside through the vent and the size of the apparatus is increased.

  Japanese Patent Application Laid-Open No. 2004-133867 proposes a heat generation unit such as a drive unit in a developing device and a non-heat generation unit in the developing device that are separated from each other.

However, in this case, there is a problem that the apparatus becomes large in order to separate the heat generating part such as the driving part and the non-heat generating part in the developing device, and as described above, the rotating shaft of the stirring member It has not been possible to appropriately prevent the toner from being fused to the shaft end portion of the stirring member due to heat generated by friction with the seal member.
JP 2003-107906 A JP 2003-57927 A JP 2005-148102 A

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems in a developing device used in an image forming apparatus such as a copying machine or a printer. Even when heat is generated by friction between the shaft and the seal member, it is an object to appropriately prevent the toner from being fused and aggregated to the end of the rotating shaft of the stirring member.

In the developing device of the present invention, in order to solve the above-described problems, the end of the rotating shaft of the stirring member that rotates in the apparatus main body and stirs the developer is rotatably held by the bearing portion. Is provided with a seal member penetrating the rotary shaft on the inner surface side of the apparatus main body, and a toner supply port for supplying toner near the end of the rotary shaft of the stirring member provided with the seal member In the apparatus, a cover member that suppresses the toner replenished from the toner replenishing port from being led to the vicinity of the end of the rotating shaft of the stirring member is provided , and the cover member includes the toner replenishing port and the toner replenishing port. It is an arcuate member arranged so as to cover the upper side of the end of the rotating shaft of the stirring member between the end of the rotating shaft of the stirring member provided with the seal member .

Further, the cover member is arranged so as to cover only the outer peripheral side of the end of the rotating shaft of the stirring member between the toner supply port and the end of the rotating shaft of the stirring member provided with the seal member. In addition, it is possible to use a cylindrical member that is open at the end opposite to the bearing portion .

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

  In the developing device of the present invention, the toner is replenished even when the toner is replenished from the toner replenishing port provided in the vicinity of the end of the rotating shaft of the stirring member rotatably held by the bearing portion as described above. The cover member prevents the toner from being guided to the end of the rotating shaft of the stirring member.

  Therefore, when the developer is agitated in the apparatus main body by rotating the agitating member, even when the end of the agitating member rotation shaft is heated by friction between the agitating member rotation shaft and the seal member, the toner Is prevented from fusing and agglomerating to the end of the rotating shaft of the agitating member, especially in a two-component developing system using a toner and a carrier as a developer to improve the developing speed. Therefore, even when the rotation speed of the stirring member is increased and the end of the rotating shaft of the stirring member that contacts the seal member is made of metal, the toner is fused to the end of the rotating shaft of the stirring member. Aggregation is appropriately prevented.

  As a result, in an image forming apparatus using such a developing device, there is no cost increase as compared to the conventional case, and the size of the device does not increase, and at the end of the rotating shaft of the stirring member in the developing device. The toner is appropriately prevented from fusing and aggregating, and the fusing and agglomerated toner is prevented from falling off the agitating member and mixed into the developer, and streaks in the formed image. Generation of noise and the like is prevented, and good image formation can be stably 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, each of the imaging cartridges 10A to 10D is exposed to the photoconductor 11, the charging device 12 for charging the surface of the photoconductor 11, and the surface of the charged photoconductor 11 according to image information. An exposure device 13 for forming an electrostatic latent image on the surface of the photoconductor 11, a developing device 20 for supplying toner to the electrostatic latent image formed on the surface of the photoconductor 11 to form a toner image, and a photoconductor A cleaning device 14 is provided for removing toner remaining on the surface of the photoconductor 11 after the toner image formed on the surface of the photoconductor 11 is transferred to the intermediate transfer belt 2.

  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 the recording medium S is guided by the timing roller 4 between the intermediate transfer belt 2 and the transfer roller 5 at an appropriate timing, and is placed 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.

  Further, in the image forming apparatus 1, four toner cartridges 9 containing toners of different colors of black, yellow, magenta and cyan are provided, and toners of corresponding colors are accommodated from the respective toner cartridges 9. The toner of the color corresponding to each developing device 20 is replenished.

  Note that the image forming apparatus is not limited to the above, and although not shown in the drawings, 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 developing device 20 in this embodiment will be specifically described.

  In the developing device 20, a developer containing toner and a carrier is used.

  Here, in the developing device 20, as shown in FIG. 2, a developing sleeve 22 having a magnet roller 22 a provided therein is provided so as to face the above-described photoconductor 11 with a required interval therebetween. .

  Further, in the developing device 20, as shown in FIGS. 3 and 4, a first transport unit 23 that transports the developer along the developing sleeve 22 is provided in the device main body 21. A first agitating member 24 provided with a screw-like blade member 24b for mixing and stirring the developer around the rotating shaft 24a is provided in the first conveying portion 23, and the first conveying portion 23 is provided. A first transport unit 23 and a second transport unit 26 for transporting the developer in the reverse direction are provided below the partition wall 25, and the developer is provided around the rotary shaft 27a in the second transport unit 26. A second agitating member 27 provided with a screw-like blade member 27b that is conveyed while being mixed and agitated is provided.

  And the circulation port 25a which connects the said 1st conveyance part 23 and the 2nd conveyance part 26 to the both ends of the partition 25 provided between the said 1st conveyance part 23 and the 2nd conveyance part 26 is provided. The developer is circulated between the first transport unit 23 and the second transport unit 26 through the circulation ports 25a.

  A toner replenishing port 28 for replenishing the toner contained in the toner cartridge 9 into the apparatus main body 21 of the developing device 20 is provided on the upper surface of the end of the first transport unit 23. The replenishing port 28 is opened and closed by an opening / closing member 29, and the toner replenishing port 28 is opened by rotating the opening / closing member 29 downward.

  In the developing device 20, the first stirring member 24 rotates the first stirring member 24 provided in the first transport unit 23 to convey the developer while mixing and stirring the developing sleeve. The developer is supplied to 22, and the amount of developer conveyed is regulated by the regulating member 30 while the developer thus fed is conveyed to the position facing the photoreceptor 11 by the developing sleeve 22. ing. Then, the developer whose amount is regulated in this manner is guided to the position facing the photoconductor 11 by the developing sleeve 22, and the toner in the developer is supplied to the photoconductor 11, and the electrostatic formed on the photoconductor 11. The latent image is developed.

  If the toner concentration in the developer is reduced as a result of the development as described above, the toner contained in the toner cartridge 9 is passed through the toner replenishing port 28 opened as described above. 21 is replenished.

  Here, in providing the 1st stirring member 24 and the 2nd stirring member 27 in said 1st conveyance part 23 and 2nd conveyance part 26, the rotating shaft in the 1st stirring member 24 and the 2nd stirring member 27 is provided. The end portions of 24 a and 27 a are protruded from the apparatus main body 21 through the bearing portion 31, and the seal member 32 that penetrates the rotary shaft 24 a is provided on the inner surface side of the apparatus main body 21 of the bearing portion 31. .

  In the developing device 20 of this embodiment, as shown in FIGS. 3 to 5, the periphery of the end 24a1 of the rotating shaft 24a of the first stirring member 24 in the vicinity where the toner supply port 28 is provided is provided. A cylindrical cover member 33 is attached to the bearing portion 31 so as to cover it.

  When the cylindrical cover member 33 is provided so as to cover the periphery of the end 24a1 of the rotation shaft 24a of the first stirring member 24 in the vicinity where the toner supply port 28 is provided, the above-described toner supply is performed. The toner replenished through the opening 28 is prevented from being guided to the end 24 a 1 of the rotation shaft 24 a of the first stirring member 24, and the rotation of the first stirring member 24 causes the rotation shaft 24 a of the first stirring member 24 to rotate. Even if the end 24a1 is in a heated state, the toner is not fused and aggregated to the end 24a1 of the rotating shaft 24a of the first stirring member 24, and good image formation is stably performed. You can do it.

  The second agitating member 27 provided in the second conveying unit 26 exists in the state of a developer in which the toner and the carrier are mixed. Therefore, the second agitating member 27 is generated at the end of the rotating shaft 27a. The heat is not dispersed by the carrier or the like in the developer so that the toner is fused and aggregated to the end of the rotating shaft 27a of the second stirring member 27, and is provided in the first transport unit 23. Further, the other end portion of the rotating shaft 24a of the first stirring member 24 is also guided in the state of the developer in which the toner and the carrier are mixed. Therefore, the heat generated at the end portion of the rotating shaft 24a is in the developer. In other words, the toner is not fused and aggregated on the other end of the rotating shaft 24a. However, it is also possible to provide the cover member 33 so as to cover the end of the rotation shaft 27a in the second stirring member 27 and the other end of the rotation shaft 24a in the first stirring member 24.

  Further, in the developing device 20 of this embodiment, the end 24a1 of the rotation shaft 24a of the first stirring member 24 is made of metal, and the end 24a1 of the rotation shaft 24a of the first stirring member 24 is easily heated. Even in this case, the toner replenished through the toner replenishing port 28 by the cylindrical cover member 33 as described above is prevented from being guided to the end 24a1 of the rotating shaft 24a of the first stirring member 24. Therefore, the toner is appropriately prevented from being fused and aggregated to the end 24a1 of the rotating shaft 24a of the first stirring member 24.

  Further, in the developing device 20 of this embodiment, a cylindrical cover is provided to prevent the toner replenished through the toner replenishing port 28 from being guided to the end 24a1 of the rotating shaft 24a of the first stirring member 24. Although the member 33 is attached to the bearing portion 31, for example, as shown in FIGS. 6A and 6B, the arc-shaped cover member 33 along the upper portion of the bearing portion 31 is subjected to the first stirring. The member 24 is attached to the bearing 31 so as to cover the upper side of the end 24a1 of the rotating shaft 24a, or the cylindrical cover member 33 is attached to the first stirring member 24 as shown in FIG. It is also possible to attach to the inner wall of the apparatus main body 21 on the outer peripheral side of the bearing portion 31 so as to cover the periphery of the end portion 24a1 of the rotating shaft 24a.

  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.

1 is a schematic cross-sectional view showing an internal structure of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view illustrating an internal structure of a developing device according to an embodiment of the present invention. In the developing device according to the above-described embodiment, a cross-sectional explanatory view showing a state where a toner supply port for supplying toner is closed by an opening / closing member. In the developing device according to the above-described embodiment, a cross-sectional explanatory view showing a state in which a toner supply port for supplying toner by rotating an opening / closing member is opened. In the developing device according to the above-described embodiment, a cross-sectional explanatory view showing a state in which a cylindrical cover member is attached to the bearing portion so as to cover the periphery of the end portion of the rotation shaft of the first stirring member. . The first modification of the developing device according to the above embodiment is shown, and the cover member formed in an arc shape is attached to the bearing portion so as to cover the upper side of the end portion of the rotating shaft of the first stirring member FIG. A second modification of the developing device according to the above embodiment is shown, and a cylindrical cover member is provided on the outer peripheral side of the bearing portion so as to cover the periphery of the end portion of the rotation shaft of the first stirring member. It is sectional explanatory drawing which showed the state attached to the inner wall of a main body.

Explanation of symbols

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 9 Toner cartridge 10A to 10D Imaging cartridge 11 Photoconductor 12 Charging device 13 Exposure device 14 Cleaning device 14 DESCRIPTION OF SYMBOLS 20 Developing apparatus 21 Apparatus main body 22 Developing sleeve 22a Magnet roller 23 1st conveyance part 24 1st stirring member 24a Rotating shaft 24a1 End part 24b blade member 25 Bulkhead 25a Circulation port 26 2nd conveyance Part 27 Second stirring member 27a Rotating shaft 27b Blade member 28 Toner supply port 29 Opening / closing member (heat radiating member)
30 restricting member 31 bearing portion 32 seal member 33 cover member S recording medium

Claims (6)

An end of the rotating shaft of the stirring member that rotates in the apparatus main body and stirs the developer is rotatably held by the bearing portion, and a seal member that penetrates the rotating shaft on the inner surface side of the apparatus main body of the bearing portion is provided. In the developing device provided with a toner replenishing port for replenishing toner near the end of the rotating shaft of the agitating member provided with the seal member, the toner replenished from the toner replenishing port And a cover member that suppresses the guide member from being guided to the vicinity of the end of the rotating shaft of the rotating shaft. The cover member is disposed between the toner replenishing port and the end of the rotating shaft of the stirring member provided with the seal member. A developing device, wherein the developing device is an arcuate member disposed so as to cover an upper side of an end portion of the rotating shaft of the stirring member . An end of the rotating shaft of the stirring member that rotates in the apparatus main body and stirs the developer is rotatably held by the bearing portion, and a seal member that penetrates the rotating shaft on the inner surface side of the apparatus main body of the bearing portion is provided. In the developing device provided with a toner replenishing port for replenishing toner near the end of the rotating shaft of the agitating member provided with the seal member, the toner replenished from the toner replenishing port And a cover member that suppresses the guide member from being guided to the vicinity of the end of the rotating shaft of the rotating shaft. The cover member is disposed between the toner replenishing port and the end of the rotating shaft of the stirring member provided with the seal member. A developing device, wherein the developing device is a cylindrical member arranged so as to cover only the outer peripheral side of the end of the rotating shaft of the stirring member . 3. The developing device according to claim 1 , wherein the developer is directed toward another stirring member disposed below and below the end of the rotating shaft of the stirring member provided with the cover member. A developing device having a circulation port for dropping .   4. The developing device according to claim 1, wherein an end portion of a rotating shaft of the stirring member that contacts the sealing member is made of metal. 5.   5. The developing device according to claim 1, wherein the developer includes toner and a carrier. 6.   An image forming apparatus comprising the developing device according to claim 1.

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