JP2009109966A - Developer transport device, developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer transport device, capable of smoothly transporting developer and suppressing deterioration in the developer, by decreasing the transport resistance of the developer, which is low cost and has long service life, and to provide a developing device and an image forming apparatus that uses the developing device. <P>SOLUTION: The developer transport device has a first developer transport member 13; a second developer transport member 14 transporting the developer in a direction reverse to the first developer transporting member; a partition wall 15 partitioning a first area 16, in which the first developer transport member 13 is disposed and a second area 17 in which the second developer transport member 14 is disposed; and an aperture part 18 disposed near the end of the partition wall 15, on the downstream side in a developer transport direction, by the first developer transport member 13 and making the first area 16 communicate with the second area 17, and transfers the developer from the first area 16 to the second area 17 through the aperture part 18. The respective developer transport members 13 and 14 are formed in the into a screw having a blade, and formed so that projected area per predetermined length of a portion of the second developer transport member 14, corresponding to the aperture part 18, is made smaller than projected area per predetermined length in other portions. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, a plotter, and a multifunction machine, and more particularly to a developer conveying apparatus that conveys the developer in the developing apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile, or a multifunction machine having at least one of these functions employing an electrophotographic system, a so-called two-component developer using toner and a magnetic carrier is used. A component developing system is known. In this two-component development method, toner is charged by friction between developers in a developing device, and the electrostatically charged image is developed by moving the charged toner with an electrostatic force generated by an electric field. The two-component developer is agitated and conveyed in the developer accommodating portion, and is frictionally charged by rubbing the toner and the carrier.

  The developer carrying member such as a developing roller provided in the developing device pumps up the developer conveyed by the magnetic field generating unit, and the developer carried on the developer carrying member is the attraction force of the magnetic field generating unit and the developer. By the rotation of the carrier, the toner is conveyed to a developing area facing the latent image carrier such as a photosensitive drum. A regulating member that regulates the amount of the developer is disposed upstream of the developing area, and the developer conveyed to the developing area is adjusted to a predetermined amount, and the developer is stressed by applying stress to the developer near the regulating member. The amount of charge is stabilized. The developer transported to the development area is sprinkled by the magnetic field generating means to form a magnetic brush, and a developing bias is applied between the developer carrier and the latent image carrier to form an electric field, Development is performed by moving the toner toward the electrostatic latent image by applying an electrostatic force to the charged toner.

  As a developer conveying member provided inside the developer accommodating portion, a screw is usually used. As a layout of the developing device, two conveying screws are horizontally arranged in the developer accommodating portion adjacent to the developer carrying member. A configuration in which the developer is circulated in parallel is generally used. As the developer conveying member, a developer screw provided on the side near the developer carrying member for supplying the developer to the developer carrying member and conveying it in the axial direction, and a developer screw provided on the side away from the developer carrying member. There is an agitation screw that conveys the agent while stirring the agent, and both ends of each screw are provided with openings that communicate the developer supply conveyance path and the agitation conveyance path. With this configuration, a developer circulation path is formed from the supply screw to the opening, from the opening to the stirring screw, from the stirring screw to the opening, and from the opening to the supply screw.

  The above-mentioned screw conveys the material in the axial direction by a spiral blade provided on the rotating shaft, and conveys the material although the force acts also in the direction orthogonal to the axial direction because the blade is inclined. I don't have the ability. For this reason, the developer is likely to stay at the opening of the developer circulation path and the developer tends to stay. Therefore, the stayed developer is pushed out by the developer transported in the axial direction by the screw and is screwed on the opposite side. Is passed on. As described above, since the opening portion becomes a resistance against the transport of the developer, there is a problem that the developer is deteriorated due to the stress due to the resistance. In order to solve this problem, in order to smoothly deliver the developer at the opening, a paddle, a reversely wound blade or the like is provided in the vicinity of the opening of the screw on the feed side so that the developer is perpendicular to the axial direction. A technique for extruding is disclosed in, for example, “Patent Document 1”. Further, for example, “Patent Document 2” or “Patent Document 3” discloses a technique for favorably delivering the developer by changing the inclination angle and the number of strips of the screw blades on the feeding side and the receiving side. .

  In recent image forming apparatuses, colorization has progressed, so-called tandem system in which four color image forming portions of yellow (yellow), magenta (red), cyan (blue), and black (black) are horizontally arranged. Image forming apparatuses are widely used. In this configuration, an image forming device such as a charging device or a developing device is provided for each of the four photoconductors arranged in the horizontal direction. In order to reduce the size of the image forming apparatus main body, the dimensions of each device are provided. Need to be small. In view of this, a configuration has been proposed in which a transport screw arranged in two vertical directions is adjacent to the developer carrier.

  In the configuration in which the conveying screw is arranged in the upper and lower two vertical directions, when the developer is transferred from the lower screw to the upper screw, the vicinity of the lower opening is filled with the staying developer, and the conveyed developing When the developer retained by the developer is pushed in and lifted, resistance due to gravity is also added, so that the developer conveyance resistance is larger than that of the horizontally disposed developer. Further, since the lower screw is buried with the developer, the effect of the paddle is small, and the upper screw also presses the pushed-out developer from the upper side, so that the conveyance resistance is increased. Therefore, in order to smoothly transport the developer from the bottom to the top, a technique for transporting the developer using a magnet roller or a conveyor belt as a transport means different from the screw is, for example, “Patent Document 4” or It is disclosed in “Patent Document 5”.

JP 2006-251440 A JP 2003-122124 A Japanese Patent Laid-Open No. 2003-107859 JP 2000-305359 A Japanese Patent No. 3494963

In the techniques disclosed in the above-mentioned “Patent Document 1”, “Patent Document 2”, and “Patent Document 3”, the screw rotates while the developer has a conveying force for feeding the developer in a direction orthogonal to the axial direction by a paddle or the like. Since it is a body, it works in the direction of returning the developer on the opposite side. Especially when a large force is required as the developer conveying force, such as in a high-speed machine, the developer tends to stay in the opening, and when the screw blades are buried in the developer near the opening, the axial direction Since the force in the direction perpendicular to the direction is offset between plus and minus, the effect of sending out the developer is almost lost. The same applies to the screw on the receiving side, and the developer sent through the opening is conveyed in the axial direction and returned to the feeding side. This returning force also becomes a developer transport resistance and causes the developer to deteriorate.
Although the techniques disclosed in “Patent Document 4” and “Patent Document 5” can reduce the developer transport resistance, the configuration is complicated, and the number of parts increases, resulting in a problem of cost increase.

  The present invention solves the above-mentioned problems, reduces developer conveyance resistance, and smoothly conveys the toner and suppresses deterioration of the developer. An object is to provide an apparatus and an image forming apparatus using the same.

  According to the first aspect of the present invention, a developer is conveyed in a direction opposite to the first developer conveying member disposed adjacent to the first developer conveying member, and a first developer conveying member conveying the developer. A second developer conveying member that conveys; a partition that separates a first region in which the first developer conveying member is disposed and a second region in which the second developer conveying member is disposed; An opening that is disposed in the vicinity of the downstream end of the partition wall in the developer transport direction by the first developer transport member and communicates the first region and the second region; In the developer transport device in which the developer is transferred from the first region to the second region and transported, each developer transport member has a screw shape having blades, and the opening of the second developer transport member The projection area per predetermined length of the part corresponding to the part is a projection surface per predetermined length in another part Characterized in that it is smaller than.

  According to a second aspect of the present invention, in the developer conveying apparatus according to the first aspect, the second developer conveying member further has a notch at a portion corresponding to the opening.

  According to a third aspect of the present invention, in the developer conveying device according to the first or second aspect, the second developer conveying member is configured such that the blades in a portion corresponding to the opening are smaller than the blades in other portions. It is formed.

  According to a fourth aspect of the present invention, in the developer conveying device according to any one of the first to third aspects, the second developer conveying member further has a number of portions corresponding to the opening in other portions. It is characterized by being formed less.

  According to a fifth aspect of the present invention, in the developer conveying device according to any one of the first to fourth aspects, the second developer conveying member further has a rotational speed of a part corresponding to the opening portion in another part. It is characterized by being higher than.

  A sixth aspect of the present invention is the developer conveying apparatus according to any one of the first to fifth aspects, further comprising a conveyance assisting means for improving a developer conveying force in the opening. .

  A seventh aspect of the present invention is the developer conveying apparatus according to the sixth aspect, wherein the conveying auxiliary means is a paddle provided on the first developer conveying member.

  According to an eighth aspect of the present invention, in the developer conveying device according to the sixth aspect, the conveyance assisting unit is a magnetic field generating unit disposed further downstream in the developer conveying direction than the opening of the second region. It is characterized by being.

  According to a ninth aspect of the present invention, in the developer transport device according to any one of the first to eighth aspects, the second developer transport member is further disposed above the first developer transport member. It is characterized by.

  A tenth aspect of the invention is a developing device including the developer conveying device according to any one of the first to ninth aspects.

  An eleventh aspect of the invention is an image forming apparatus having the developing device according to the tenth aspect.

  According to the present invention, the developer can pass by making the projected area per predetermined length of the developer conveying member located on the developer receiving side smaller than the projected area per predetermined length of other parts. By widening the path, it is possible to reduce the transport resistance at the opening, which is a developer delivery section, and to suppress the deterioration of the developer, thereby providing a long-life developer transport device.

  FIG. 1 shows an image forming apparatus employing the first embodiment of the present invention. In FIG. 1, a photosensitive drum 2 that is a latent image carrier is disposed inside the main body of the image forming apparatus 1, and a charging device 3, an exposure device 4, a developing device 5, and a transfer device 6 are arranged around the photosensitive drum 2. The cleaning device 7 is disposed in order. In addition, a sheet feeding device (not shown) having a sheet feeding tray storing transfer paper 8 and a fixing device 9 are disposed inside the apparatus main body.

  The photosensitive drum 2 is formed by forming an organic photosensitive layer exhibiting photosensitivity on the surface of an element tube such as aluminum, and is driven to rotate in the direction of the arrow in the figure by a driving means (not shown). The surface of the rotating photosensitive drum 2 is uniformly charged by the charging device 3 so as to have a predetermined charging potential, and then the laser beam modulated based on the image information by the exposure device 4 is applied to the photosensitive drum 2. An electrostatic latent image is formed by scanning and irradiating in the axial direction. The electrostatic latent image formed on the photosensitive drum 2 is developed by supplying charged toner from the developing device 5 in a developing region facing the developing device 5, and is visualized to become a toner image. .

  On the other hand, the transfer paper 8 is fed from a paper feeder (not shown), and the fed transfer paper 8 is fed to a transfer portion where the photosensitive drum 2 and the transfer device 6 face each other at a predetermined timing. The transfer device 6 applies a charge having a polarity opposite to that of the toner image on the photosensitive drum 2 to the transfer paper 8, whereby the toner image formed on the photosensitive drum 2 is transferred to the transfer paper 8. The The transfer paper 8 onto which the image has been transferred is separated from the photosensitive drum 2 and sent to the fixing device 9 where the image is fixed on the surface of the fixing device 9 by the action of heat and pressure and then discharged. The surface of the photosensitive drum 2 is cleaned by the cleaning device 7 to remove residual toner, and then uniformly charged by the charging device 3 to be ready for the next image forming process.

  Here, the characteristic part of this invention is demonstrated. FIG. 2 is a front sectional view of the developing device 5. The developing device 5 has an opening at a portion facing the photosensitive drum 2, and a part of the opening is exposed from the opening to expose the photosensitive drum 2. And a developing roller 10 as a developer carrying member which is a non-magnetic rotating member. Inside the developing roller 10, a magnet fixed so as not to rotate is disposed. The developing device 5 is provided with a developer accommodating portion 11 in which a two-component developer containing toner and a magnetic carrier is accommodated. A doctor blade 12 that regulates the layer thickness of the developer layer formed on the surface of the developing roller 10 is disposed above the developing roller 10.

  3 is a plan sectional view of the developing device 5. As shown in FIGS. 2 and 3, a stirring screw 13 as a first developer conveying member and a second developer conveying member are provided in the developer accommodating portion 11. As shown in FIG. A supply screw 14 as a member is disposed. The stirring screw 13 is disposed on the side away from the developing roller 10 and conveys the developer from right to left in FIG. 3, and the supply screw 14 is disposed adjacent to the developing roller 10 to remove the developer. Transport from left to right in FIG. The screws 13 and 14 are separated from each other by a partition wall 15, whereby the developer storage unit 11 is provided with a supply screw 14 in a first region 16 where the stirring screw 13 is provided. The region is divided into second regions 17. Openings 18 and 19 for communicating the first region 16 and the second region 17 are formed at both ends of the partition wall 15, and the developer is moved to an arrow in FIG. 3 by rotating the screws 13 and 14. Cycle in the direction.

  The developer conveyed to the vicinity of the developing roller 10 by the supply screw 14 is pumped up to the surface of the developing roller 10 by the magnetic force of the magnet in the developing roller 10 and is conveyed by the rotation of the developing roller 10. The developer pumped up on the surface of the developing roller 10 is regulated in thickness by the doctor blade 12, and a certain amount of developer is conveyed to the developing area and faces the photosensitive drum 2, and at the same time, the developer is developed by the doctor blade 12. By applying stress to the toner, frictional charging of the toner in the developer is promoted.

  In the developing region, a magnetic brush is formed on the developing roller 10 by magnetic force, and the formed magnetic brush is in the same direction as the moving direction of the photosensitive drum 2 by the rotation of the developing roller 10 and is faster than the moving speed of the photosensitive drum 2. It is moved at a high speed and passes through the development region while its tip is in sliding contact with the photosensitive drum 2. At this time, a developing bias is applied to the developing roller 10 from a power source (not shown), and a developing potential acts on the toner that forms the tip of the magnetic brush that is in sliding contact with the photosensitive drum 2, and this toner is applied from the surface of the magnetic carrier to the photosensitive member. The toner image is formed by electrostatic transfer to the electrostatic latent image portion of the drum 2. With the rotation of the developing roller 10, the magnetic brush after passing through the developing region is returned to the supply screw 14 in the developer storage unit 11.

  The developer conveyed to the downstream end portion of the supply screw 14 by the rotation passes through the opening 19 and is delivered to the stirring screw 13. A paddle 20 is formed at a portion corresponding to the opening 19 of the supply screw 14 as a conveyance assisting means for extruding the developer in a direction orthogonal to the axial direction, and corresponds to the opening 19 of the stirring screw 13. The part is formed so that the outer diameter of the blade is smaller than that of the other part by α and the gap with the partition wall 15 is increased. As a result, the path through which the developer can pass is wide, and the force to push back the developer is reduced by the smaller blades. Thus, by reducing the blade on the side where the developer is delivered, the conveyance resistance of the developer passing through the opening 19 can be reduced. When the stirring screw 13 is viewed from the opening 19 side, the projection area per predetermined length is formed smaller than the projection area of the predetermined per unit length of other regions because the blades are smaller. The other region referred to here is a region constituted only by blades and shafts, excluding a region where members added for the functions of stirring and delivery such as the paddle 20 are provided.

  The developer sent from the supply screw 14 to the agitation screw 13 is agitated with the toner replenished by the toner replenishment means based on a signal from a toner concentration detection means (not shown) while being conveyed in the axial direction by the rotation of the agitation screw 13. The toner is controlled to have an appropriate toner density. The developer conveyed to the downstream end of the stirring screw 13 passes through the opening 18 and is delivered to the supply screw 14. A paddle 21 as a conveyance assisting device similar to the paddle 20 is also formed at a portion corresponding to the opening 18 of the stirring screw 13, and the portion corresponding to the opening 18 of the supply screw 14 has other blade outer diameters. It is formed to have a smaller diameter by α than the portion, and is formed to have a larger gap with the partition wall 15.

  With the above-described configuration, the developer can pass by making the projected area per predetermined length of each of the screws 13 and 14 positioned on the developer receiving side smaller than the projected area per predetermined length of other portions. By providing a wide path, it is possible to reduce the transport resistance in each of the openings 18 and 19 which are the developer delivery section, to suppress the deterioration of the developer, and to provide a long-life developer transport device. be able to. Further, by providing the paddles 20 and 21, it is possible to compensate for a decrease in conveying force due to a decrease in developer resistance at the developer delivery portion, and to supply a stable developer.

  FIG. 4 is a front sectional view of a developing device used in the second embodiment of the present invention, and FIG. 5 is a sectional side view thereof. In the developing device 22 shown in the second embodiment, the supply screw 14 is arranged slightly parallel to the position above the developing roller 10, and the stirring screw 13 is arranged below the supply screw 14. A partition wall 23 is disposed between the screws 13 and 14, whereby the developer accommodating portion 11 is divided into a first region 16 having the stirring screw 13 and a second region 17 having the supply screw 14. Has been. Openings 24 and 25 that connect the first region 16 and the second region 17 are formed at both ends of the partition wall 23.

  The developer is transported in the direction of the arrow in FIG. 5 by the supply screw 14 and is supplied so as to fall from above onto the pumping pole of the developing roller 10 beyond the partition wall 23. The developer conveyed to the end without being supplied to the developing roller 10 falls from the opening 25 to the stirring screw 13 disposed in the lower stage. In the stirring screw 13, the developer is conveyed in the opposite direction to the supply screw 14, and the developer returned from the developing roller 10, the toner replenished by a toner replenishing means (not shown), and the developer falling from the supply screw 14 are agitated. Is done. The developer conveyed to the end of the stirring screw 13 while being stirred is lifted upward through the opening 24 and is transferred to the supply screw 14 again.

  A paddle 26 as a conveyance assist means is formed in a portion corresponding to the opening 24 of the stirring screw 13, and a notch 27 is formed in a blade in a portion corresponding to the opening 24 of the supply screw 14. A path for passing is formed. Since the force for pressing the developer from above does not work at the portion where the notch 27 is formed, the developer conveyance resistance can be reduced. When the supply screw 14 is viewed from the opening 24, the projection area is formed smaller than that of the other parts by the amount of the cutout 27 formed. Since the conveying force of the supply screw 14 is reduced at the site where the notch 27 is formed, the wall surface of the developer storage unit 11 located at the site downstream of the opening 24 in the developer conveying direction by the supply screw 14 is magnetically applied. A magnet 28 serving as a magnetic field generating unit is disposed as a conveyance auxiliary unit that supplements the developer conveyance force by attracting the developer.

  With the above-described configuration, the same effect as that of the first embodiment can be obtained. In the developing device 22 having the circulation configuration described above, the developer pumped up by the developing roller 10 and passed through the developing region does not immediately return to the developing region, but is returned to the agitating screw 13 and sufficiently agitated before being supplied to the supply screw 14. Therefore, the developer supplied to the developing roller 10 is uniformly stirred and is always adjusted to a stable toner density. Further, the developing device 22 shown in the second embodiment has an advantage that the width of the developing device 22 can be made narrower than that of the developing device 5 because the screws 13 and 14 are arranged in two upper and lower stages.

  FIG. 6 is a front sectional view of a developing device used in the third embodiment of the present invention, and FIG. 7 is a sectional side view thereof. In the developing device 29 shown in the third embodiment, the supply screw 14 is arranged in parallel near the right side of the developing roller 10, the stirring screw 13 is arranged below the supply screw 14, and the developing roller 10 A recovery screw 30 is disposed below. A partition wall 23 is disposed between the screws 13 and 14, and the developer accommodating portion 11 is divided into a first region 16 and a second region 17. A partition wall 15 is disposed between the screws 13 and 30.

  The supply screw 14 supplies the developer to the developing roller 10 while transporting the developer in the axial direction, and the developer on the developing roller 10 that has passed through the developing region falls and is recovered to the recovery screw 30, and the recovery screw 30 is supplied to the supply screw 30. The developer is conveyed in the same direction as 14. The developer conveyed to the end of the supply screw 14 without being supplied to the developing roller 10 falls from the opening 25 to the stirring screw 13, and the developer conveyed to the end by the recovery screw 30 is also the opening 19. And passed to the stirring screw 13.

  The developer transferred to the stirring screw 13 from the supply screw 14 and the recovery screw 30 is conveyed in the axial direction by the stirring screw 13, lifted through the opening 24 at the end thereof, and transferred to the supply screw 14. . The supply screw 14 has two blades to improve the conveying force and improve the pumping property to the developing roller 10. However, if the number of blades is large, the developer conveyance resistance at the opening 24 increases. Therefore, only the part corresponding to the opening 24 has a single blade. When the supply screw 14 is viewed from the opening 24 side, the projected area of the part where the blades are formed on one line is almost half that of the other part where the blades are formed on two lines. .

  The supply screw 14 is divided into two with the point D shown in FIG. 7 as a boundary, and a single strip portion 14A having blades formed on a single strip is provided on the left side in FIG. The two strips 14B, which are rotationally driven by the driving means and have two blades, are rotationally driven by a second driving means (not shown) provided on the right side in FIG. The rotation speed of the supply screw 14 by the first drive means is set higher than the rotation speed by the second drive means, and thereby the conveying force of the supply screw 14 at the portion corresponding to the opening 24 is improved. . Also with this configuration, it is possible to obtain the same operational effects as those of the first and second embodiments described above.

  In each of the above-described embodiments, by reducing the outer diameter of the blade, providing notches, and reducing the number of blades, the developer transport resistance in the opening can be reduced by widening the path through which the developer can pass. Although the configuration is reduced, a configuration in which these are combined may be employed. In each of the above embodiments, an example in which the present invention is applied to a direct transfer type image forming apparatus has been described. However, the present invention can also be applied to a tandem type color copying apparatus. A color copying apparatus to which the present invention can be applied will be described below.

  In FIG. 8, a color copying apparatus 31 as an image forming apparatus includes an image forming unit 32 positioned at the center of the apparatus main body, a paper feeding unit 33 positioned on the right side of the image forming unit 32, and an upper side of the image forming unit 32. And an image reading unit (not shown).

  The image forming unit 32 is provided with an intermediate transfer belt 34 as an intermediate transfer body having an image transfer surface extending in the horizontal direction, and a configuration for forming an image on the upper surface of the intermediate transfer belt 34, that is, a yellow color. Four photosensitive drums 35 carrying toner images of toners of four colors, magenta, cyan, and black are disposed along the transfer surface of the intermediate transfer belt 34. The intermediate transfer belt 34 is stretched around a driving roller 36, a secondary transfer counter roller 37, and a support roller 38, and moves in the same direction as the rotation direction of each photoconductive drum 35 at a position facing each photoconductive drum 35. It is configured to be possible. A belt cleaning device 39 for cleaning the surface of the intermediate transfer belt 34 is disposed at a position facing the driving roller 36 with the intermediate transfer belt 34 interposed therebetween.

  The image forming section including each photoconductive drum 35 is configured to be selectable according to a single-color or multiple-color image forming mode, and the image forming section according to the selected image forming mode has been described above. An image forming process similar to that of the form is performed. As the developing device, the same ones as the developing devices 5, 22, and 29 described above are used, and the configuration and operation around each photosensitive drum 35 are substantially the same as those in the above embodiment, but formed on each photosensitive drum 35. The toner images of the respective colors are superimposed and transferred onto the intermediate transfer belt 34 instead of onto the transfer paper 8 to form a primary transfer image that is a color image.

  The paper feed unit 33 includes a paper feed tray 40 that stacks and stores recording materials such as paper as recording media, and a paper feed roller that separates and feeds the recording materials in the paper feed tray 40 one by one from the top. 41, a pair of conveying rollers 42 for conveying the recording material fed by the paper feed roller 41, and after the recording material is temporarily stopped to correct the oblique deviation, the leading edge of the image on the intermediate transfer belt 34 and the recording material A registration roller pair 43 that feeds the recording material toward the transfer nip portion at a timing that coincides with a predetermined position in the transport direction.

  The toner image primary-transferred from each photosensitive drum 35 onto the intermediate transfer belt 34 is electrostatically applied to the conveyed recording material by a transfer bias applied to the secondary transfer roller 44 by a bias applying unit (not shown). Secondary transfer. The recording material 45 to which the image has been transferred is conveyed to a fixing device 47 through a conveyance guide 46, and a toner image on the recording material 45 is formed by the action of a heating roller 49 incorporating a heater 48 and a pressure roller 50 pressed against the heating roller 49. It is fixed.

  In this tandem type color copying apparatus 31, by using the same developing device as that of the developing device 22 shown in the second embodiment, the horizontal dimension can be kept small, and each photosensitive drum 35 can be kept small. It is possible to reduce the size of the apparatus by reducing the distance between them.

  In each of the above-described embodiments, examples in which the direct transfer type image forming apparatus 1 and the tandem type color copying apparatus 31 are used as the image forming apparatus to which the present invention can be applied have been described. The image forming apparatus is not limited to these, and the present invention can also be applied to other image forming apparatuses such as a facsimile, a printer, and a multifunction machine of these.

1 is a schematic front view of an image forming apparatus employing a first embodiment of the present invention. 1 is a front sectional view of a developing device used in a first embodiment of the present invention. 1 is a plan sectional view of a developing device used in a first embodiment of the present invention. It is front sectional drawing of the image development apparatus used for the 2nd Embodiment of this invention. It is a sectional side view of the developing device used for the 2nd Embodiment of this invention. It is front sectional drawing of the image development apparatus used for the 3rd Embodiment of this invention. It is a sectional side view of the developing device used for the 3rd Embodiment of this invention. 1 is a schematic front view showing a color copying apparatus to which the present invention is applicable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,31 Image forming apparatus 5,22,29 Development apparatus 13 1st developer conveyance member (stirring screw)
14 Second developer conveying member (supply screw)
15, 23 Partition 16 First region 17 Second region 18, 19, 24, 25 Opening 20, 21, 26 Conveyance assisting means (paddle)
27 Notch 28 Transport auxiliary means (magnetic field generating means)

Claims (11)

A first developer transport member that transports the developer, and a second developer transport that is disposed adjacent to the first developer transport member and transports the developer in a direction opposite to the first developer transport member. A partition that separates the member, a first region in which the first developer transport member is disposed, and a second region in which the second developer transport member is disposed, and the first developer in the partition An opening that is disposed in the vicinity of the downstream end of the developer conveying direction by the conveying member and that communicates the first area and the second area. From the first area to the second area through the opening. In the developer transport device in which the developer is transferred and transported,
Each developer conveying member has a screw shape having blades, and a projected area per predetermined length of a portion corresponding to the opening of the second developer conveying member is a projected area per predetermined length in another portion. A developer transporting device, wherein the developer transporting device is formed smaller than the above. The developer conveying device according to claim 1,
The developer conveying apparatus, wherein the second developer conveying member has a notch at a portion corresponding to the opening. The developer conveying device according to claim 1 or 2,
The developer transport device according to claim 2, wherein the second developer transport member is formed such that the blades corresponding to the openings are smaller than the blades of other portions. In the developer conveyance device according to any one of claims 1 to 3,
The developer conveying device, wherein the second developer conveying member is formed so that the number of stripes corresponding to the opening portion is smaller than that of other parts. In the developer conveyance device according to any one of claims 1 to 4,
The developer transport device according to claim 2, wherein the second developer transport member has a higher rotational speed at a portion corresponding to the opening than at other portions. In the developer conveyance device according to any one of claims 1 to 5,
A developer transport device comprising transport assisting means for improving the transport force of the developer in the opening. The developer conveying device according to claim 6, wherein
The developer conveying apparatus, wherein the conveyance assisting means is a paddle provided on the first developer conveying member. The developer conveying device according to claim 6, wherein
The developer conveying apparatus, wherein the conveyance assisting means is a magnetic field generating means disposed downstream of the opening in the second region in the developer conveying direction. In the developer conveyance device according to any one of claims 1 to 8,
The developer conveying apparatus, wherein the second developer conveying member is disposed above the first developer conveying member.   A developing device comprising the developer conveying device according to claim 1.   An image forming apparatus comprising the developing device according to claim 10.

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