JP2008310200A - Powder agitating device, developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a powder agitating device which is compact and excellent in dispersing, mixing and agitating functions, a developing device and an image forming apparatus. <P>SOLUTION: The powder agitating device is equipped with a rotatable agitating screw 310 agitating powder such as toner. The agitating screw 310 is formed of a revolving shaft 311 driven to be rotated, and blade members formed around the revolving shaft. The first blade member 312 whose powder feeding direction is a forward direction, and the second blade member 313 whose feeding direction is a reverse direction are formed to be discontinuously divided at every 180° in a periphery direction of the shaft relative to the rotating direction of the rotary shaft 311. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a powder stirring device, a developing device, and an image forming apparatus, and more particularly to a powder stirring device, a developing device, and an image forming device provided with a rotatable stirring member that stirs powder.

  As a powder agitation device provided with a means for mixing powder, there is a developer mixing device in a developing device using an electrophotographic process. Such a developer mixing device is arranged to uniformly mix toner and carrier.

  Conventionally, in order to visualize an electrostatic latent image formed in the shape of an image carrier, a so-called two-component developing apparatus using a two-component developer composed of a toner and a carrier as a developer has been employed.

  In such a developing device, a developer agitating / conveying device disposed in a developer container for containing the developer is used to stir the two-component developer to frictionally charge the toner, and then has a magnetic pole inside. It is conveyed toward the developer carrying member. Then, this developer is carried on the surface of the developer carrying member, conveyed, and supplied to the electrostatic latent image on the image carrying member to develop it.

  FIG. 10 is a configuration diagram illustrating an example of a conventional developer agitating / conveying member 100. In the developer stirring and conveying member shown in FIG. 10, screw blade members 102 and 103 are spirally formed around the rotation shaft 101, and the developer is conveyed in the axial direction by the rotation. The developer agitating and conveying member 100 mixes and agitates the developer composed of toner and carrier in the axial direction by a spiral screw, so that the developers conveyed and mixed on one axis are arranged in parallel in the longitudinal direction. The most common method is a biaxial stirring method in which conveyance and mixing are performed with another shaft.

  FIG. 11 is a cross-sectional view showing an example of a biaxial stirring type developing apparatus. In the developing device 200, two stirring members 211 and 212 are disposed in a developer container 210, and the developer 213 supplied from the developer supply unit 230 is stirred and conveyed to a photosensitive roller 220 that is an image carrier. It is made to adhere (refer patent document 1).

  However, since the developing device described above requires a developer container having only two stirring members, it is difficult to cope with the recent downsizing of the image forming apparatus. For this reason, the following stirring apparatus has been proposed.

  In Patent Document 2, a plurality of rod-like projecting members are installed between spiral blade members formed around the rotating shaft. The developer in the developing device provided with the developer agitating and conveying member is conveyed in the axial direction by the rotation of the spiral blade member, and thrown in the centrifugal direction by the rotation of the protruding member and stirred. ing.

In Patent Document 3, as shown in FIG. 12, in order to improve the dispersibility and mixing of the developer, the conveying screw 45 includes a rotating shaft 45a, a screw blade member 45b formed around the rotating shaft 45a, and a rotating shaft 45a. And a linear member 45c installed by twisting with respect to the above.
Japanese Patent Laid-Open No. 11-030905 JP 2000-19823 A JP 2005-17872 A

  However, in the invention described in Patent Document 2, there is a function of throwing the developer in the centrifugal direction by a plurality of projecting members protruding from the rotating shaft of the spiral blade member, but the developer is kicked in the axial direction. There is almost no function to scatter. For this reason, the effect which suppresses generation | occurrence | production of the screw pitch nonuniformity mentioned above is hardly acquired. In addition, since the number of protruding members in the rotation axis direction of the developer agitating / conveying member is small and the density is small, the developer's own weight falling movement to the gap portion that occurs behind the protruding member immediately after the protruding member enters the developer is used. In this embodiment, almost no stirring effect of the developer can be obtained, and there is room for improvement with respect to the dispersion mixing and stirring function of the flowing developer. Moreover, since it is the structure which assumed the biaxial stirring system fundamentally as mentioned above, there exists a problem that it is difficult to respond to size reduction.

  The invention described in Patent Document 3 has a problem that it is difficult to cope with downsizing because the configuration basically assumes a biaxial stirring method.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a powder stirrer, a developing device, and an image forming apparatus at low cost with a small size and excellent dispersion mixing and stirring functions.

  The invention of claim 1 is a powder agitating device comprising a rotatable agitating member for agitating powder, wherein the agitating member comprises a rotational shaft that is driven to rotate and a blade formed around the rotational shaft. The blade member includes a forward blade member whose forward direction is the powder feed direction, and a reverse blade member whose feed direction is the reverse direction. It is a powder agitator characterized by being formed by being discontinuously divided every 180 degrees in direction.

  According to a second aspect of the present invention, in the powder agitator according to the first aspect, the forward blade member and the reverse blade member are arranged at equal pitch intervals, and the forward blade member and the reverse blade member are arranged. Is arranged so as to be shifted by a predetermined length in the longitudinal direction of the rotating shaft.

  According to a third aspect of the present invention, in the powder agitating device according to the second aspect, the radial blade member has a predetermined distance along the longitudinal direction of the rotating shaft between the forward blade member and the reverse blade member. It is characterized by being formed discontinuously every time.

  According to a fourth aspect of the present invention, in the powder agitator according to any one of the first to third aspects, the forward blade member and the reverse blade member have a substantially elliptical shape. .

  According to a fifth aspect of the present invention, in the powder agitator according to any one of the first to third aspects, the forward blade member and the reverse blade member have a spiral shape.

  According to a sixth aspect of the present invention, there is provided a developer container that contains a developer containing toner and a carrier, a developer carrier that carries and conveys the developer, and the developer carrier that is disposed in the vicinity of the developer carrier. A regulating member that regulates the amount of developer drawn on the body and imparts a desired tribo to the developer, and conveys the developer in the developer container while agitating the developer and holds the developer on the developer carrier A developing device having at least one rotatable stirring means for causing the stirring means to comprise the powder stirring device according to any one of claims 1 to 4 in a developing container. The developing device.

  A seventh aspect of the present invention is an image forming apparatus characterized in that an image is formed by an electrophotographic process including the developing device according to the sixth aspect.

  According to an eighth aspect of the present invention, there is provided a process cartridge which is detachable from the main body of the image forming apparatus and comprises the developing device according to the sixth aspect.

  According to the present invention, the stirring member is constituted by a rotary shaft that is rotationally driven, and a blade member that is formed around the rotary shaft, and the blade member is 180 degrees in the axial direction with respect to the rotational direction of the rotary shaft. Since the forward blade member whose powder feed direction is the forward direction and the reverse blade member whose feed direction is the reverse direction are formed discontinuously divided every time, the stirring efficiency is improved and the uniaxial Even with this configuration, the stirring performance equivalent to that of the biaxial stirring device can be obtained, and a small-sized powder stirring device, a developing device, and an image forming device excellent in dispersion mixing and stirring functions can be obtained at low cost. There is an effect.

  Embodiments as the best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of a color image forming apparatus according to an embodiment of the present invention. First, a process for obtaining a color image will be described. The color image forming apparatus includes a transfer belt apparatus 10 having an intermediate transfer belt 11 and four image stations. Each image station has 20Y, 20C, 20M, and 20Bk as image carriers (hereinafter referred to as photosensitive drums). There are dedicated charging devices 30Y, 30C, 30M, 30Bk, developing devices 50Y, 50C, 50M, 50Bk, and cleaning devices 40Y, 40C, 40M, 40Bk.

  The toner bottle 9 stores toner therein and replenishes the toner, and is filled with yellow (Y), cyan (C), magenta (M), and black (Bk) toners from the left in the drawing. Then, the developing devices 50Y, 50C, 50M, and 50Bk of the respective colors are replenished by a predetermined replenishment amount through a conveyance path (not shown).

  When the transfer paper 2 is fed from the paper feed cassette 1 by the paper feed roller 3, when the leading edge of the transfer paper 2 reaches the registration roller pair 4, it is detected by a sensor (not shown). The pair 4 conveys the transfer paper 2 to the nip portion between the secondary transfer roller 5 and the intermediate transfer belt 11.

  The photosensitive drums 20Y, 20C, 20M, and 20Bk, which are uniformly charged in advance by the charging devices 30Y, 30C, 30M, and 30Bk, are exposed and scanned with laser light by the optical writing device 8, and the photosensitive drums 20Y, 20C, and 20M are obtained. , An electrostatic latent image is formed on 20 Bk.

  The electrostatic latent images are developed by the developing devices 50Y, 50C, 50M, and 50Bk for the respective colors, and yellow, cyan, magenta, and black toner images are formed on the surfaces of the photosensitive drums 20Y, 20C, 20M, and 20Bk.

  Next, a voltage is applied to the primary transfer rollers 12Y, 12C, 12M, and 12Bk, and the toner on the photosensitive drums 20Y, 20C, 20M, and 20Bk is sequentially transferred onto the intermediate transfer belt 11. At this time, the image forming operation for each color is executed while shifting the timing from the upstream side toward the downstream side so that the toner image is transferred to the same position on the intermediate transfer belt 11.

  The image formed on the intermediate transfer belt 11 is conveyed to the position of the secondary transfer roller 5 and is secondarily transferred to the transfer paper 2.

  The transfer paper 2 onto which the toner images of the respective colors have been transferred is conveyed to the fixing device 6 and thermally fixed, discharged by a discharge roller 7 and stacked on a discharge tray.

  The residual toner on the photosensitive drums 20Y, 20C, 20M, and 20Bk is cleaned by the respective cleaning devices 40Y, 40C, 40M, and 40Bk, and then charged by the charging devices 30Y, 30C, 30M, and 30Bk, and the next operation is performed. Prepare for the statue.

  The residual toner on the intermediate transfer belt 11 is cleaned by the intermediate transfer belt cleaning device 13 to prepare for the next image forming process.

  In the image forming apparatus according to this example, the photosensitive drum as the image carrier, the developing device, and the cleaning device are formed as an integrally formed process cartridge, and are arranged to be detachable from the image forming apparatus main body. Is done. FIG. 2 is a perspective view showing a process cartridge attached to and detached from the image forming apparatus main body. As shown in FIG. 2, the process cartridges 60Y, 60C, 60M, and 60Bk for Y, C, M, and Bk colors are arranged in the image forming apparatus main body 70 in such a manner that they can be extracted from the image forming apparatus main body 70. The user can replace the image carrier, the developing device, the charging unit, and the cleaning unit together in a cartridge form.

  Next, the developing device will be described. FIG. 3 is a cross-sectional view showing a process cartridge provided with a stirring device according to the embodiment, and FIG. 4 is an enlarged cross-sectional view showing a developing device for the process cartridge shown in FIG.

  The process cartridge 60 including the developing device 50 regulates the developing case 55 having an opening, the developing sleeve 51 disposed so as to face the surface of the photosensitive drum 20 and the developer on the developing sleeve 51 to a constant layer thickness. And a stirring screw 53 which is a stirring member disposed at a position facing the developing blade 51. The cleaning device 40 includes a cleaning case 43 having an opening, a cleaning blade 41 for cleaning residual toner on the photosensitive drum 20, and a waste toner screw 42 for transporting the cleaned waste toner to a waste toner bottle (not shown). It is comprised including.

  The transfer belt device 10 includes an intermediate transfer belt 11, a primary transfer roller 12 that transfers a toner image on the photosensitive drum 20 to the intermediate transfer belt 11, and an intermediate transfer belt case 14 that holds these components. ing. Reference numeral 30 denotes a charging roller as a charging device, reference numeral 31 denotes a cleaning roller for the charging roller, and reference numeral R denotes laser light from the optical writing device.

  As shown in FIG. 4, the developing device 50 has a single stirring screw 53 disposed in a developing case 55. The agitating screw 53 agitates and conveys the toner 81 supplied from the toner replenishing portion 82 disposed on the upper lid 83 in the developing case 55.

  Next, the stirring screw disposed in the developing device 50 will be described. FIG. 5 is a perspective view illustrating a stirring screw of the transport device according to the embodiment. In this example, the stirring screw 310 includes a first blade member 312 and a second blade member 313 that are formed around the rotation shaft 311. In this example, the first blade member 312 is formed so that the feeding direction of the toner, which is powder, is the forward direction in the rotation direction of the rotation shaft 311 (indicated by an arrow in the figure). Further, the second blade member 313 is divided and formed discontinuously so that the toner feeding direction is opposite to the same rotation direction.

  In this example, the first blade member 312 and the second blade member 313 have a part of a spiral shape. When the rotary shaft 311 is rotationally driven in one direction, the toner in the developing case 55 provided with the stirring screw 310 moves in the forward direction in the vicinity thereof by the first blade member 312 and the second adjacent thereto. The blade member 313 reciprocates in the reverse direction and is gradually made uniform in the developing case 55.

  The inventor conducted an experiment comparing the stirring screw according to the example with a conventional biaxial stirring screw. In the experiment, a magenta developer is put in half from the center of the container (both have the same longitudinal length), and an equal amount of cyan developer is put in the opposite half from the center at the same toner concentration. In the uniaxial stirring method using the stirring screw according to the above, the stirring screw was rotated at the same rotational speed, and when the color in the developing device became uniform, the mixing and stirring time until that time was examined. The screw diameter of the biaxial stirring method stirring screw was 18 mm, and the screw pitch was 25 mm.

  The stirring screw according to the example had the following dimensions. FIG. 6 is a perspective view showing the dimensions of the stirring screw used in the comparative experiment. The stirring screw 320 has a first blade member 322 that is fed in the forward direction to the rotating shaft 321 and a second blade member 323 that is fed in the reverse direction, and the pitch between the blade members of the first blade member 322 is changed. The pitch between the blade members of the second blade member 323 was equal to 25 mm and 25 mm. Moreover, the screw diameter of the stirring screw 310 is 18 mm, the first blade member 322 and the second blade member 323 are shifted by 8 mm in the axial longitudinal direction, and the second blade member 323 and the next first blade member 322 are Was shifted by 17 mm in the longitudinal direction of the shaft.

  In this comparative example, the stirring time of 20 seconds was required in the biaxial stirring method, whereas 50 seconds was required in the stirring screw 310 according to this example.

  Next, the stirring screw 330 according to another example was compared. FIG. 7 is a perspective view showing the dimensions of another stirring screw used in the comparative experiment. The agitating screw 330 is provided with a first blade member 332 that is fed forward to the rotating shaft 331 and a second blade member 333 that is fed in the opposite direction, and the first blade member 332 and the second blade member 333 are arranged. In the longitudinal direction of the shaft, they were shifted at equal intervals of 12.5 mm and 12.5 mm.

  When this stirring screw 330 was used, the stirring time was 40 seconds, and improvement in powder mixing properties was confirmed. The first blade member and the second blade member are offset at equal intervals, so that it is considered that the developer in the container is easily mixed evenly.

  Next, another example of the stirring screw will be described. FIG. 8 is a perspective view showing a stirring screw according to the second embodiment. The stirring screw 340 according to this example has a smaller inclination angle with respect to the rotation shaft 341 of the first and second blade members 341 and 342. When the same experiment as the above comparative experiment was performed using the stirring screw 340 according to this example, the stirring time was 35 seconds. The agent is reciprocated by the width of one blade member to make it uniform uniformly in the vessel, and the mixing and stirring efficiency is better than the uniaxial stirring method using the stirring screw according to the other examples above. It is thought that it became.

  In addition, it turns out that it is important that the powder feed direction of a 1st blade member and a 2nd blade member is a reverse direction from the said comparison. The shape of the blade member can be a part of a spiral shape as in the above example, or may be a part of an elliptical shape.

  In the present invention, the diameter of the rotating shaft of the stirring screw and the diameter of the blade member can also be set as appropriate. Furthermore, it has been found that when the shaft rotation speed is increased too much, the agent mixing property tends to decrease. As soon as the agent on one side of the shaft is transported in one direction, the shaft on the other side is transported in the opposite direction, so that the shaft rotation speed is too fast, the powder slips and idles, and is likely to stay in place. It is thought to be because. Along with the shape and size of the blade member, the angle of inclination, etc., the shaft rotation speed may be selected so that the agent mixing property does not deteriorate.

  Further, a stirring screw 350 according to another example will be described. FIG. 9 is a perspective view showing a stirring screw according to a third embodiment. In the stirring screw 350 according to this example, the first blade member 352 and the second blade member 353 are disposed around the rotation shaft 351 and the first blade member 352 is disposed in the same manner as the second embodiment described above. In addition, plate blade mylar members 355 and 356 of a thin resin plate (mylar film) having a rectangular parallelepiped shape or another shape are arranged in a comb shape between the second blade members 353. As a result of the experiment described above, it was found that the powder mixing property was further improved when the stirring screw 350 according to this example was used.

  In addition, a stirring screw in which only the plate blade mylar members 355 and 356 are installed on the rotation shaft 351 at equal intervals without the first blade member 352 and the second blade portion 353 being arranged is visually observed. As a result of confirmation, the blade member Mylar member bites into the inner wall of the powder container and bends, and when it is opened at the upper part of the toner surface, it looks like the toner is thrown upward, and further collides with the upper lid of the powder container. It was found that the toner diffused and gradually uniformed, and that when the rotational speed of the rotating shaft was increased, the powder was thrown upward and the opportunity for diffusion was increased.

  However, since the plate blade mylar member alone does not have a function of feeding the agent in the axial longitudinal direction, the powder mixing property in the axial longitudinal direction (container longitudinal direction) is insufficient. By disposing the plate blade mylar members 355 and 356 in the radial direction along the axial direction between the first blade member 352 and the second blade member 353 described above, one blade member by rotation of the rotation shaft 351 is provided. The reciprocating motion of the powder with the width of the minute and the powder diffusion motion of the plate blade member Mylar member were synergistic, and the powder mixing property in the axial longitudinal direction could be improved. The experimental mixing time was 20 seconds.

1 is a configuration diagram of a color image forming apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view illustrating a process cartridge attached to and detached from an image forming apparatus main body. It is sectional drawing which shows the process cartridge provided with the stirring apparatus which concerns on an Example. FIG. 4 is an enlarged sectional view showing a developing device of the process cartridge shown in FIG. 3. It is a perspective view which shows the stirring screw of the conveying apparatus which concerns on an Example. It is a perspective view which shows the dimension of the stirring screw used for the comparative experiment. It is a perspective view which shows the dimension of the other stirring screw used for the comparative experiment. It is a perspective view which shows the stirring screw which concerns on a 2nd Example. It is a perspective view which shows the stirring screw which concerns on a 3rd Example. It is a block diagram which shows an example of the conventional developer stirring conveyance member. It is sectional drawing which shows an example of the developing apparatus of a biaxial stirring system. It is sectional drawing which shows an example of the other conventional image development apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper feed cassette 2 Transfer paper 3 Paper feed roller 4 Registration roller pair 5 Secondary transfer roller 6 Fixing device 7 Paper discharge roller 8 Device 9 Toner bottle 10 Transfer belt device 11 Intermediate transfer belts 12Y, 12C, 12M, 12Bk Primary transfer Roller 13 Intermediate transfer belt cleaning device 14 Intermediate transfer belt case 20Y, 20C, 20M, 20Bk Photosensitive drums 30Y, 30C, 30M, 30Bk Charging device 40Y, 40C, 40M, 40Bk Cleaning device 41 Cleaning blade 42 Waste toner screw 43 Cleaning case 45 Conveying screw 50Y, 50C, 50M, 50Bk Developing device 51 Developing sleeve 52 Doctor blade 53 Stirring screw 55 Developing case 60 Process cartridge 60Y, 60C, 60M, 60Bk Process cartridge G 70 Image forming apparatus main body 81 Toner 82 Toner replenishing portion 83 Upper lid 310 Stirring screw 311 Rotating shaft 312 First blade member 313 Second blade member 320 Stirring screw 321 Rotating shaft 322 First blade member 323 Second blade member 330 Stirring screw 331 Rotating shaft 332 First blade member 333 Second blade member 340 Stirring screw 341, 342 First and second blade member 341 Rotating shaft 350 Stirring screw 351 Rotating shaft 352 First blade member 353 Second Blade member 355, 356 Plate blade mylar member

Claims (8)

In a powder agitation apparatus provided with a rotatable agitating member for agitating powder,
The stirring member includes a rotary shaft that is driven to rotate, and a blade member that is formed around the rotation shaft, and the blade member includes a forward blade member whose powder feed direction is a forward direction; A powder agitator, wherein a reverse blade member whose feed direction is reverse is formed by being discontinuously divided every 180 degrees in the axial circumferential direction with respect to the rotation direction of the rotary shaft.   The forward blade member and the reverse blade member are arranged at equal pitch intervals, and the forward blade member and the reverse blade member are arranged to be shifted by a predetermined length in the longitudinal direction of the rotating shaft. The powder agitation apparatus according to claim 1.   The radial blade member is formed discontinuously at a predetermined distance along the longitudinal direction of the rotating shaft between the forward blade member and the reverse blade member. Powder agitation equipment.   The powder agitator according to any one of claims 1 to 3, wherein the forward blade member and the reverse blade member have a shape that is part of a substantially elliptical shape.   The powder agitator according to any one of claims 1 to 3, wherein the forward blade member and the reverse blade member have a spiral shape. A developer container containing a developer including toner and a carrier; a developer carrier for carrying and transporting the developer; and pumping up the developer on the developer carrier disposed in the vicinity of the developer carrier A regulating member for regulating the amount and imparting a desired tribo to the developer, and at least a rotatable member for transporting the developer in the developer container while stirring the developer to carry the developer on the developer carrier. In a developing device having one stirring means,
5. A developing device, wherein the stirring means is configured by arranging the powder stirring device according to any one of claims 1 to 4 in a developing container.   An image forming apparatus, wherein an image is formed by an electrophotographic process comprising the developing device according to claim 6.   A process cartridge comprising the developing device according to claim 6, wherein the process cartridge is detachable from an image forming apparatus main body.