JP2006162810A - Developing device, cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent replenishment toner from reaching a developing sleeve or the like in a low or uncharged state in an electrophotographic image forming apparatus, and copying is repeated for a long period of time, or the use of toner consumption is reduced for a long period of time In addition, the present invention provides a developing device capable of outputting a stable image free from background contamination and scattering.
A developer carrying member, a plurality of developer agitating and conveying members arranged in a horizontal direction with the developer carrying member, a partition member provided between the developer agitating and conveying members, and the partition member And a toner replenishing means for replenishing toner from the end of the developer agitating / conveying member, and an image carrier using a two-component developer comprising toner and a carrier. In the developing device that visualizes the electrostatic latent image and forms an image, at least a part of the wall surface of the first developer stirring unit that replenishes toner is movable.
[Selection] Figure 3

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to a developer transport portion of a developing device using a two-component developer.

In recent years, along with demands for downsizing and personalization of image forming apparatuses using electrophotographic technology such as copying machines and printers, downsizing of developing devices has been attempted. In addition to such a request, in addition to a disposable developing device that replaces the developing device when the toner runs out, a latent image carrier (photosensitive member) on which an electrostatic latent image of a document image is formed in addition to the developing device. ), And a so-called process cartridge in which a cleaning unit for removing toner remaining on the photosensitive member is integrated is also widely used.
However, such a miniaturized developing device has a small amount of developer containing toner and magnetic carrier. In addition, since the space for the developer agitating portion is also inevitably reduced, the time until the replenished toner reaches the developing area is short, and the replenishment toner and the developer (including the magnetic carrier) are not sufficiently agitated. As a result, the charge amount of the toner is reduced and floating toner is easily generated. When this floating toner is generated, the background stain of the transfer paper becomes severe, which is not preferable. Such a phenomenon occurs particularly remarkably because a large amount of toner is replenished into the developer agitating unit at a time when an original having a high image area ratio is continuously copied.
In addition, as the machine speed increases, the developer agitating / conveying member rotates at high speed, and the toner is 3 to 12 μm fine particles, so that a part of the replenished toner is scattered without being well agitated with the developer. , Float or move on the developer surface. When such toner is transported to the developing roller and transported to the development area, uncharged, reversely charged, and weakly charged poorly charged toner may cause image quality problems such as non-image area background contamination, density unevenness, and toner scattering. cause.
In order to solve such a problem, a scattering prevention member is provided to prevent the toner replenished from the toner replenishing portion from sliding on the developer surface and being conveyed to the developing roller side screw portion without being charged. Has been proposed (see, for example, Patent Document 1).
In addition, it has been proposed to use a screw without a central shaft so that toner can be sufficiently stirred even in a miniaturized developing device (see, for example, Patent Document 2).
However, these conventional techniques place emphasis on uniform stirring / dispersion of toner among stirring / dispersion and charging, which are two conditions that must be satisfied before the toner reaches the developing portion. In other words, the screw section is provided with a function of uniformly supplying the replenished toner to the developer, and the toner charging is covered by the strong friction between the developer regulating blade and the developer as in the conventional case.
In such a development system, the toner is subjected to a large stress in the developer reservoir on the back side of the developer regulating blade, and the developer is deteriorated. Since the deteriorated toner has a weaker charging ability than a new toner, the charge amount distribution is broadened through an image forming process over a long period of time, resulting in a decrease in image quality. However, if the stress on the back of the developer regulating blade is easily reduced, the toner will be insufficiently charged, and on the contrary, there may be increased scumming and scattering.
JP-A-9-106161 Japanese Patent Laid-Open No. 10-221936

As described above, when the stress behind the developer regulating blade is easily reduced, the toner is insufficiently charged, and there is a problem in that the background contamination / scattering increases.
Therefore, the present invention has been made in consideration of the above-described circumstances, and can prevent the replenished toner from directly reaching the developing sleeve and its surrounding developer in a low-charged or uncharged state, and can be copied over a long period of time. It is an object of the present invention to provide a developing device capable of stable image output with no background contamination or scattering even when the process is repeated or when a special usage state with low toner consumption is extended for a long period of time. To do.

In order to solve the above-described problems, the invention described in claim 1 includes a developer carrier, a plurality of developer stirring and conveying members that are arranged substantially in parallel with the developer carrier, and are driven to rotate. A partition member provided between the developer agitating and conveying members, a communication path formed on the partition member for returning the developer, a developer containing container for housing the components, and the developer agitating and conveying member A toner replenishing means for replenishing toner from the end of the toner, and a developing device for visualizing an electrostatic latent image formed on the image carrier by a two-component developer comprising toner and carrier. A first developer stirring and conveying member to which toner is directly replenished includes a screw blade and a cylindrical sleeve in which an inner wall is integrated with an outer periphery of the screw blade so as to surround at least a part of the screw blade. , Characterized in that it is composed of.
The invention of claim 2 is characterized in that, in claim 1, plate-like blades extending in the axial direction are further provided on the inner wall of the cylindrical sleeve.
The invention according to claim 3 is provided between the developer carrying member, a plurality of developer stirring and conveying members that are arranged substantially parallel to the developer carrying member and driven to rotate, and between these developer stirring and conveying members. A partition member, a communication passage formed on the partition member for returning the developer, a developer container for housing the components, and a toner replenishing unit for replenishing toner from an end of the developer stirring and conveying member A first developer that directly replenishes toner from the toner replenishing means in a developing device that visualizes an electrostatic latent image formed on an image carrier with a two-component developer comprising toner and carrier. The stirring and conveying member is composed of a screw blade and a cylindrical sleeve disposed on the outer periphery so as to surround at least a part of the screw blade and rotatable relative to the screw blade. And butterflies.
According to a fourth aspect of the present invention, in the third aspect, the gap between the outer periphery of the screw blade and the inner wall of the cylindrical sleeve is 1 mm or less.
According to a fifth aspect of the present invention, in the first, second, third, or fourth aspect, the endless vehicle travels in a predetermined direction between the first developer agitating / conveying member and the inner bottom surface of the developer containing container positioned below the first developer agitating and conveying member. A belt is stretched.
According to a sixth aspect of the present invention, in any one of the first to fifth aspects, a magnetic force generating means is provided below the first developer agitating and conveying member.
According to a seventh aspect of the invention, at least the developing device according to any one of the first to sixth aspects and at least one of the latent image carrier, the charging device, and the latent image carrier cleaning device are combined. It is characterized by being integrated.
The invention according to claim 8 is the development according to any one of claims 1 to 6, wherein a latent image carrier and a dry developer for developing the latent image on the latent image carrier are accommodated. And a transfer means for transferring the toner image on the latent image carrier visualized by the developing device to a transfer target.
A ninth aspect of the invention is characterized in that the process cartridge according to the seventh aspect is provided.

According to the present invention, a developer carrying member, a plurality of developer stirring and conveying members arranged in the horizontal direction together with the developer carrying member, a partition member provided between these developer stirring and conveying members, A two-component developer comprising a toner and a carrier, comprising a communication passage formed at both ends of the partition member for returning the developer, and a toner replenishing means for replenishing toner from the end of the developer agitating and conveying member. In a developing device for visualizing an electrostatic latent image formed on an image carrier to form an image, the development is characterized in that at least a part of the wall surface of the first developer stirring unit for replenishing toner is movable. By the apparatus, the developer inside the developer accommodating container is well agitated by rotating the inner wall of the developer accommodating container of the first developer agitating section. Further, since the screw blades are provided on the inner wall of the cylindrical sleeve, the developer is conveyed while being agitated with the rotation of the cylindrical sleeve. Therefore, the developer can be favorably conveyed without accumulating in one place.
In addition, by providing screw-like blades on the inner wall of the cylindrical sleeve and attaching auxiliary blades extending in the substantially longitudinal direction of the cylindrical sleeve, the agent that has accumulated in the lower part of the agent container and the agent that falls from the wall surface in accordance with gravity Stirring / dispersing and charging of the replenishment toner can be performed more satisfactorily by the agitation having the three functions of agitation for lifting and agitation for mixing and mixing the replenishment toner that slides on the developer surface.
Further, since the rotational speed of the cylinder and the speed of the screw can be driven separately, it becomes easy to control the rubbing and the conveying speed. In addition, the same configuration can be easily made with two parts, and the cost can be reduced, rather than processing the cylindrical inner wall so that screw-like blades are raised.
If a belt that runs endlessly is arranged at the bottom of the developer container of the first developer agitation unit and the belt surface moves in the same direction as the screw rotation, the belt surface and the developer The developer is agitated by friction, and the replenishment toner can be agitated, dispersed and charged satisfactorily.
Further, by providing the magnetic field generating means below the first developer agitating unit, the carrier receives a magnetic force and is pressed against the bottom surface of the developer accommodating unit, and the frictional force accompanying the movement of the bottom surface increases. Accordingly, the toner charge rises quickly in the first developer agitation unit. In addition, since a magnetic brush is formed on the surface of the developer, the effect of blocking the replenished toner from sliding up is great, which can greatly contribute to the stirring and dispersion of the replenished toner.
As described above, the first developer agitation unit not only stirs and disperses replenished toner but also adds a charging start-up function, thereby applying a strong stress to the developer near the doctor blade as in the past. No need to give. If the torque applied to the developing roller is weakened, the deterioration of the toner carrier can be suppressed, and the charging ability of the toner carrier can be maintained. Therefore, according to the present invention, not only initial background contamination and toner scattering but also good image formation without background contamination and toner scattering over a long period of time can be achieved.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 1 is an internal configuration diagram of a color image forming apparatus to which a developing device according to an embodiment of the present invention is applied.
Specifically, it is an electrophotographic copying apparatus of a tandem type indirect transfer system, where reference numeral 100 is a copying apparatus main body, 200 is a paper feed table on which the copying apparatus main body 100 is placed, and 300 is a scanner (reading optical system) mounted on the copying apparatus main body 100. , 400 is an automatic document feeder (ADF) mounted on the apparatus 400.
An endless belt-like intermediate transfer member 10 extending in the lateral direction is provided at the center position of the copying apparatus main body 100. In the illustrated example, the intermediate transfer member is wound around three support rollers 14, 15, and 16 so as to be able to rotate and convey clockwise in the drawing. In this illustrated example, an intermediate transfer body cleaning device 17 that removes residual toner remaining on the intermediate transfer body 10 after image transfer is provided to the left of the second support roller 15 among the three support rollers.
Further, among the three support rollers, the intermediate transfer member 10 stretched between the first support roller 14 and the second support roller 15 has black, yellow, magenta, and cyan along the transport direction. The tandem image forming unit 20 is configured by arranging the four image forming units 18 side by side.
An exposure device 21 is further provided immediately above the tandem image forming unit 20 as shown in FIG. On the other hand, a secondary transfer device 22 is provided on the opposite side of the intermediate transfer body 10 from the tandem image forming unit 20. In the illustrated example, the secondary transfer device 22 is configured by spanning a secondary transfer belt 24, which is an endless belt, between two rollers 23, and is pressed against the third support roller 16 via the intermediate transfer body 10. The image on the intermediate transfer body 10 is transferred to a sheet.
A fixing device 25 for fixing the transfer image on the sheet is provided beside the secondary transfer device 22. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 that is an endless belt. The secondary transfer device 22 described above also has a sheet transport function for transporting the image-transferred sheet to the fixing device 25. In the illustrated example, a sheet reversing device 28 for reversing the sheet so as to record images on both sides of the sheet is provided below the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming unit 20 described above. Is provided.

Now, when making a copy using this color electrophotographic apparatus, a document is set on the document table 30 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed by it.
When a start switch (not shown) is pressed, when a document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. Immediately, the scanner 300 is driven, and the first traveling body 33 and the second traveling body 34 travel. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34 and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.
When a start switch (not shown) is pressed, one of the support rollers 14, 15 and 16 is rotationally driven by a drive motor (not shown), and the other two support rollers are driven to rotate, so that the intermediate transfer body 10 is moved. Rotate and convey. At the same time, the individual image forming means 18 rotates the photoconductor 40 to form black, yellow, magenta, and cyan monochrome images on each photoconductor 40. Then, along with the conveyance of the intermediate transfer member 10, the single color images are sequentially transferred to form a composite color image on the intermediate transfer member 10.

On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller 45. Then, the sheets are separated one by one into the paper feed path 46, transported by the transport roller 47, guided to the paper feed path 48 in the copying machine main body 100, and abutted against the registration roller 49 and stopped.
Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer member 10, the sheet is fed between the intermediate transfer member 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. A color image is recorded on the sheet. The image-transferred sheet is conveyed by the secondary transfer device 22 and sent to the fixing device 25. The fixing device 25 applies heat and pressure to fix the transferred image. Are discharged and stacked on the discharge tray 57.
Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and the image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56. On the other hand, the intermediate transfer body 10 after the image transfer is removed by the intermediate transfer body cleaning device 17 to remove residual toner remaining on the intermediate transfer body 10 after the image transfer, so that the tandem image forming unit 20 can prepare for another image formation.
Now, in the tandem image forming unit 20 described above, the individual image forming means 18 is more specifically, for example, as shown in FIG. 2, around a drum-shaped photoconductor 40, a charging device 60, a developing device 61, and a primary device. A transfer device 62, a photoreceptor cleaning device 63, a charge removal device 64, and the like are provided.
The developing device 61 includes a developer supply container 65, a toner replenishment side stirring screw 66 as a first developer stirring and conveying member, a developer carrier side stirring screw 67 as a second developer stirring and conveying member, and a developer. A carrier (developing roller) 68 is provided. A supply port (not shown) is provided on the outer wall of the container of the first developer stirring section 66A, and toner is supplied from a toner supply device (toner supply means) (not shown). The agitation screw 66 on the toner replenishment side agitates and conveys the toner replenished from the toner replenishing device and the developer (two-component developer having magnetic carrier particles and toner) in the developer container 65. Further, the agitation screw 67 of the second developer agitation unit (developer carrier side) 67A agitates and conveys the developer in the developer container 65.

The agitation screw 66 of the first developer agitation unit 66A according to the first embodiment of the present invention will be described in detail with reference to FIGS. 3 (a) and 3 (b). (A) is a three-dimensional view and (b) is a cross-sectional view.
The present invention is provided between the developer carrying member 40, a plurality of developer stirring and conveying members 66 and 67 which are arranged substantially parallel to the developer carrying member and are driven to rotate, and these developer stirring and carrying members. A partition member 65a to be formed, a communication passage (not shown) formed at each of both ends of the partition member 65a in the front-rear direction, and a developer containing container 65 for housing the components 66, 67, 65a. A developing device that visualizes an electrostatic latent image formed on an image carrier with a two-component developer composed of toner and a carrier. Is.
The characteristic configuration is that the first developer agitating / conveying member 66 to which toner is directly replenished from the toner replenishing means is configured so that the screw blade 145 and the outer periphery of the screw blade are surrounded by at least a part of the screw blade. And a cylindrical sleeve 146 in which the inner wall is integrated.
That is, the screw 145 which is a component part of the stirring screw 66 has a threshold 145 a that is continuous in a screw shape on the inner wall of the cylindrical sleeve 146. The cylindrical sleeve 146 is interrupted at both ends of the screw portion because of a toner replenishment portion, a developer receiving portion from the second developer stirring portion 67A, and a delivery portion to the second developer stirring portion. . Reference numeral 145b denotes a rotation center axis.
In short, the stirring screw 66 according to the present embodiment has a cylindrical sleeve 146 that is integrated on the outer peripheral surface of the screw 145 on the inner peripheral surface over a predetermined width from the central portion of the screw 145 extending linearly to both sides in the axial direction. It has a configuration. On the inner wall of the cylindrical sleeve 146, spiral blades (threshold 145a) constituting the screw 145 are continuously integrated, and both ends of the spiral blade of the screw 145 protrude from both axial ends of the cylindrical sleeve. It is integrated with the rotation center shaft 145b.
In order to appropriately circulate the developer, the length of the screw 145 protruding from both ends of the cylindrical sleeve 146 (discontinuity at both ends) was set to 30 mm. Further, when the developer stirring member 66 is disposed in the first developer stirring portion 66A, in order to prevent the developer from entering the outside of the cylindrical sleeve 146, as shown in FIG. There is no step between the outer periphery and the agent is not easily clogged. Further, the outer diameter of the portion where the cylindrical sleeve 146 is interrupted (the screw blade portion protruding from both ends of the cylindrical sleeve) is 1 to 3 mm thinner so as not to contact the container outer wall 65.
By providing such a stirring member 66, the toner replenished from a toner replenishing portion (not shown) enters the cylindrical sleeve 146 having a screw-like threshold 145a inside. Since the entire wall surface provided with the threshold 145a moves in the cylindrical sleeve 146, the amount of sliding between the developer and the wall surface including the threshold increases, and the screw-like shape stands on the inner wall while being well stirred and dispersed. It is conveyed in the direction of the rotation axis of the cylindrical sleeve 146 by the threshold 145 a, and eventually escapes from the cylindrical sleeve 146 and is delivered to the second developer agitating member 67. Therefore, the toner conveyed to the development area can be satisfactorily image-formed without causing background staining or scattering.

Next, a second embodiment of the present invention will be described. FIG. 5 shows a modification of the developer stirring member. A plate-like blade 145 c extending in the substantially longitudinal direction of the cylindrical sleeve is provided on the inner wall of the cylindrical sleeve 146.
FIG. 6 shows a cross-sectional view of a portion where there is a blade (the screw blade 145a is not shown). The blade 145c stirs the developer accumulated in the lower part of the developer accommodating portion, and stirs the toner sliding upward on the developer surface. Furthermore, by further lifting and stirring the agent that falls from the wall surface according to gravity, stirring, dispersion, and charging of the replenishing toner can be performed better.
In this example, the screw blades 145a are fixed to the inner wall of the cylindrical sleeve 146, while the blades 145c are fixed to other portions of the inner wall to improve the stirring / dispersing force and charging ability.
With the above configuration, the replenished toner is sufficiently agitated and dispersed before being conveyed to the development area, and background stain and toner scattering can be prevented. That is, by providing screw-like blades 145a on the inner wall of the cylindrical sleeve 146 and attaching auxiliary blades 145c extending substantially in the longitudinal direction of the cylindrical sleeve, stirring of the agent accumulated in the lower part of the agent containing portion, according to gravity from the wall surface Stirring / dispersing and charging of the replenishment toner can be performed more satisfactorily by agitation having three functions of agitation for further lifting the dropping agent and agitation for mixing and mixing the replenishment toner that slides on the developer surface.

Next, a third embodiment of the present invention will be described.
This embodiment is provided between the developer carrying member 40, a plurality of developer stirring and conveying members 66 and 67 which are arranged substantially parallel to the developer carrying member and are driven to rotate, and these developer stirring and conveying members. Partition member 65a, a communication passage (not shown) formed in the partition member for returning the developer, a developer storage container 65 for storing each of the components 66, 67, 65a, and an end of the developer stirring and conveying member And a toner replenishing means (not shown) for replenishing toner from the portion, and a developing device for visualizing an electrostatic latent image formed on the image carrier by a two-component developer composed of toner and carrier. The first developer agitating / conveying member 66 that is directly replenished with toner from the means is disposed on the outer periphery so as to surround the screw blade 145 and at least a part of the screw blade. And-menu blade relative rotatable cylindrical sleeve 246, and a.
That is, in this embodiment, the first developer stirring member 66 is composed of two parts. The first part is a cylindrical sleeve 146, and the second part is a screw 145d without a central axis. As shown in FIG. 7, both the cylindrical sleeve 146 and the screw 145d are connected to the rotation center shafts 145b at both ends, and can be driven to rotate independently of each other. That is, the cylindrical sleeve 146 and the screw 145d are not integrated and can be rotated relatively independently.
In this embodiment, the clearance between the outer peripheral portion of the screw blade and the inner wall of the cylindrical sleeve is set as narrow as 1 mm, so that the developer can be prevented from slipping through and more efficient stirring and charging can be performed.
Further, as a modification of the screw 145d without the central axis that is inserted into the cylindrical sleeve 146, an auxiliary blade 145c as shown in FIG. 5 may be provided at the tip of the screw 145d so as to rotate integrally.
As shown in FIG. 8, the screw 145 to be inserted into the cylindrical sleeve 146 does not have to be a type without a central axis, and may be a normal type screw 145f with a central axis 145e. You may fix the auxiliary blade | wing 145c shown in FIG. 5 to each front-end | tip of this screw 145f.
With the above configuration, the replenished toner is sufficiently agitated and dispersed before being conveyed to the development area, and background stain and toner scattering can be prevented.
Further, in each of the above embodiments, if the surface roughness inside the cylinder is increased, the frictional force between the rotating inner wall of the cylinder (including the screw) and the developer increases, and the rising of charging is further improved.

Next, a fourth embodiment of the present invention will be described.
This embodiment is characterized in that an endless belt 70 running in a predetermined direction is stretched between the first developer agitating / conveying member 66 and the inner bottom surface of the developer containing container located below the first developer agitating / conveying member 66. is there.
That is, in this embodiment, a part of the inner wall of the first developer agitating portion 66A is a seamless belt surface (endless belt surface), and the developer is agitated and dispersed by rubbing against the belt surface. It was.
The configuration using the seamless belt will be described in detail with reference to FIG. The belt 70 is configured such that the developer and the belt surface are in direct contact with each other on the bottom surface of the developer accommodating portion 65, and is rotated by a belt driving roller 71. The belt surface constituting a part of the inner wall of the developer container is pushed downward by the outer periphery of the screw blade of the first developer agitating screw 66 to form the inner wall shape (concave circle) (FIG. 10 ( b)).
Further, at the boundary portion between the belt surface and the fixed wall surface of the developer container 65, the gap is protected by a seal member 72 or the like so that the developer does not enter the gap between the wall surfaces. In this example, the stirring screw and the belt were driven so that the outer peripheral speed of the stirring screw blade and the speed of the belt surface were equal.
Alternatively, the moving direction of the belt surface and the rotating direction of the screw may be the same direction, and the moving speed of the belt surface may be 1.2 times the speed of the tip of the screw blade.
In this embodiment, the type having no central axis is used as the agitating screw 66. However, as shown in FIG. 8, a type having a central axis 145e may be used, and a stirring effect may be further added to a part of the screw spring. It may be provided with auxiliary blades that increase Further, the belt and the cylindrical sleeve may be driven at different speeds.
By adopting such a configuration, the rubbing between the wall surface of the developer container 65 and the developer is increased, the stirring and dispersion of the developer is promoted, and background contamination and scattering are reduced. In particular, since the stirrability of the developer collected in the lower portion of the developer accommodating portion is improved, the developer in the vicinity of the detection portion of the toner concentration sensor 73 disposed inside the belt is satisfactorily replaced. Control is possible.

Next, a fifth embodiment of the present invention will be described. In this embodiment, a permanent magnet having a saturation magnetic flux density of 1000 G is disposed 5 mm from the lowermost surface of the developer below the first developer stirring section 66A. Moreover, the stirring member used in Example 2 was used as a screw. As a result, since the replenished toner in which the developer rising up in the first developer agitating portion 66A is entangled and mixed with the developer as the screw rotates, the agitation / dispersion of the replenished toner is remarkably improved. Further, since the rubbing between the developer and the inner wall of the cylindrical sleeve becomes strong and the charge rising of the replenishment toner is accelerated, toner scattering and background contamination in the development region can be eliminated.
In other words, by providing the magnetic field generating means below the first developer agitating and conveying member 66, the carrier receives a magnetic force and is pressed against the inner bottom surface of the developer accommodating portion, and the toner moves between the inner bottom surface. The frictional force associated with increases. Accordingly, the toner charge rises quickly in the first developer agitating and conveying unit. In addition, since a magnetic brush is formed on the surface of the developer, the effect of blocking the replenished toner from sliding up is great, which can greatly contribute to the stirring and dispersion of the replenished toner.

As described above, the first developer agitating unit 66A improves the toner charge start-up function, so that a conventional doctor blade (means for regulating the toner layer thickness on the peripheral surface of the developing roller facing the photoreceptor) is used. It is possible to weaken the fact that the developer is charged with a strong stress in the vicinity. Therefore, it is possible to extend the life of the toner, and since the toner is extended, the background stain and toner scattering do not occur even during long-term image output.
Therefore, we actually verified it. The 5% image area chart is 100,000 in combination with the developing roller in which the magnetic force of the pumping pole of the developing roller is weakened and the torque applied to the developing roller is reduced by 30% under the arrangement condition of the stirring member and the permanent magnet of Example 2. The images were output. As a result, even after outputting 100,000 images, it was in a good state with no background stains or scattering.
A process cartridge in which each developing device shown in each of the above embodiments and at least one of a latent image carrier, a charging device, and a latent image carrier cleaning device are combined is also within the scope of the present invention. included.
Further, an electrophotographic image forming apparatus (printer, copying machine, facsimile apparatus) using this process cartridge is also included in the scope of the present invention.
According to each embodiment of the present invention, the first developer agitating unit 66A adds not only the agitation / dispersion of the replenishment toner but also the charging start-up function, so that the development is performed in the vicinity of the doctor blade as in the past. It is no longer necessary to apply strong stress to the agent. If the torque applied to the developing roller is weakened, the deterioration of the toner carrier can be suppressed, and the charging ability of the toner carrier can be maintained. Therefore, according to the present invention, not only initial background contamination and toner scattering but also good image formation without background contamination and toner scattering over a long period of time can be achieved.

1 is a cross-sectional view of a tandem electrophotographic apparatus as an example of using a developing device of the present invention. 1 is a configuration diagram of a developing device of a tandem image forming unit according to the present invention. The block diagram of the image development apparatus which has a stirring screw in the cylindrical sleeve inner wall of this invention. The block diagram which shows the detail of a structure of the edge part of the developer stirring part of this invention. FIG. 3 is a configuration diagram of a developer stirring unit having blades on a cylindrical sleeve of the present invention. FIG. 3 is a radial cross-sectional view of the cylindrical sleeve of the present invention in a developer stirring state. The block diagram of the stirring part which the cylindrical sleeve and stirring screw of this invention rotate independently. The block diagram in case the stirring screw of this invention has a center axis | shaft. The block diagram when a part of inner wall of the stirring part of this invention is a seamless belt. Explanatory drawing which shows the relationship between the stirring part seamless belt of this invention, and a screw.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Intermediate transfer body 14, 14, 16 Support roller, 17 Intermediate transfer body cleaning apparatus, 18 Image formation means, 20 Tandem image formation part, 21 Exposure apparatus, 22 Secondary transfer apparatus, 23 Roller, 24 Secondary transfer belt, 25 fixing device, 26 fixing belt, 27 pressure roller, 28 sheet reversing device, 30 document table, 32 contact glass, 33 first traveling body, 34 second traveling body, 35 imaging lens, 36 reading sensor, 42 paper feeding Roller, 43 paper bank, 44 paper cassette, 45 separation roller, 46 paper feed path, 47 transport roller, 48 paper feed path, 49 registration roller, 55 switching claw, 56 discharge roller, 57 paper discharge tray, 60 charging device, 61 Developing device, 62 Primary transfer device, 63 Photoconductor cleaning device, 64 Static eliminating device, 65 Development Container, 66A first stirring section, 66 toner supply side stirring screw, 67A second stirring section, 67 developer carrier side stirring screw, 68 developer carrier (developing roller), 70 belt, 71 belt drive roller, 72 seal member, 73 toner density sensor, 100 copying machine main body, 145 screw, 145a screw-like threshold, 145b rotation center axis, 145c blade, 145d screw without center axis (independent rotation), 145f screw with center axis ( (Independent rotation) 146 Cylindrical sleeve 200 Feeding table 300 Scanner 400 Automatic document feeder (ADF)

Claims (9)

A developer carrying member, a plurality of developer stirring and conveying members that are arranged substantially in parallel with the developer carrying member and driven to rotate, a partition member provided between the developer stirring and conveying members, and the partition member And a toner supply means for supplying toner from an end of the developer agitating / conveying member, and a toner supply means for supplying the toner from the end of the developer agitating / conveying member. In a developing device for visualizing an electrostatic latent image formed on an image carrier by a two-component developer comprising a carrier and a carrier,
The first developer agitating and conveying member that is directly replenished with toner from the toner replenishing means comprises a screw blade and a cylindrical sleeve in which an inner wall is integrated on the outer periphery of the screw blade so as to surround at least a part of the screw blade And a developing device.   2. The developing device according to claim 1, wherein a plate-like blade extending in the axial direction is further provided on an inner wall of the cylindrical sleeve. A developer carrying member, a plurality of developer stirring and conveying members that are arranged substantially in parallel with the developer carrying member and driven to rotate, a partition member provided between the developer stirring and conveying members, and the partition member And a toner supply means for supplying toner from an end of the developer agitating / conveying member, and a toner supply means for supplying the toner from the end of the developer agitating / conveying member. In a developing device for visualizing an electrostatic latent image formed on an image carrier by a two-component developer comprising a carrier and a carrier,
The first developer agitating and conveying member that is directly replenished with toner from the toner replenishing means is a screw blade and a cylinder that is disposed on the outer periphery so as to surround at least a part of the screw blade and is rotatable relative to the screw blade. And a developing device.   4. The developing device according to claim 3, wherein a gap between the outer periphery of the screw blade and the inner wall of the cylindrical sleeve is 1 mm or less.   An endless belt that travels in a predetermined direction is stretched between the first developer agitating and conveying member and an inner bottom surface of a developer container located below the first agitating and conveying member. The developing device according to 3 or 4.   6. The developing device according to claim 1, further comprising a magnetic force generating unit provided below the first developer agitating and conveying member.   At least one of the developing device according to any one of claims 1 to 6 and at least one of the latent image carrier, the charging device, and the latent image carrier cleaning device is combined and integrated. To process cartridge.   A developing device according to any one of claims 1 to 6 containing a latent image carrier and a dry developer for developing a latent image on the latent image carrier, and the developing device. An image forming apparatus comprising: a transfer unit that transfers a toner image on the latent image carrier that has been visualized to a transfer target. An image forming apparatus comprising the process cartridge according to claim 7.

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