JP2011191350A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact developing device including a collecting/stirring/conveying member and a supplied developer stirring member which are vertically disposed beside a developing sleeve so as to circularly convey the developer, and the developer separated from the developing sleeve is prevented from being deposited again on the developing sleeve, accordingly, image density reduction is prevented. <P>SOLUTION: The collection screw 35 is disposed near a developer separation area 9 of the developing sleeve 32. A supply screw 34 is disposed near a pumping area 9 so as to circularly convey the developer between the collection screw 35 and the supply screw 34. A pumping magnetic pole N2 and a developer separation magnetic pole N1 incorporated in the developing sleeve are arranged at a distance. A guiding member 46 for guiding the developer separated from the surface of the developing sleeve to facilitate movement of the developer in a direction to separate from the vicinity of the surface of the developing sleeve is disposed in the developer separation area 9 while separating from the surface of the developing sleeve. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and a process cartridge and an image forming apparatus employing the developing device.

  In recent years, as a color image forming apparatus, four photoconductors of yellow, magenta, cyan, and black are arranged side by side in the horizontal direction, and each color toner image formed on each photoconductor is superimposed to obtain a color image. Is widely used. In the tandem type image forming apparatus, it is desired to reduce the size of the apparatus, and it is necessary to arrange the photoconductors with narrow intervals. For this purpose, it is desirable to reduce the lateral size of each developing device that forms a toner image on each photoconductor.

  As a developing device, a device using a two-component developer composed of toner and a magnetic carrier (hereinafter simply referred to as a developer) is widely known. In such a developing device, a developer is carried on a cylindrical developing sleeve containing a magnetic pole, conveyed to a developing area facing the photoreceptor, and developed by attaching toner to the electrostatic latent image on the surface of the photoreceptor. In this developing device, it is important to sufficiently mix the magnetic carrier and the toner and to supply the developer with the target toner concentration and toner charge amount to the developing sleeve in order to improve the image quality. For this reason, conventionally, a developing device having a configuration in which two screws 51 and 52 are arranged laterally on the side of the developing sleeve 32 as shown in FIG. 9 is used. In this configuration, the developer is circulated and transported between the two screws 51 and 52 to sufficiently stir and mix the developer having the target toner concentration and toner charge amount, and the developer close to the developing sleeve 32. 51 is supplied to the developing sleeve 32. Further, the developer separated from the developing sleeve 32 is collected by the screw 51 close to the developing sleeve. However, it is difficult to reduce the horizontal size of the developing device having two screws 51 and 52 arranged in the horizontal direction.

  Patent Document 1 describes a developing device that reduces the size in the horizontal direction by arranging two screws in the vertical direction beside the developing sleeve 32. FIG. 6 is a schematic configuration diagram of the developing device of Patent Document 1. In this developing device, a supply screw 34 is disposed in the vicinity of the agent pumping area 10 of the developing sleeve 32, and a recovery screw 35 is disposed in the vicinity of the agent separating area 9 of the developing sleeve 32 that is vertically below the supply screw 34. Further, a partition plate 36 divides the supply conveyance path 37 including the supply screw 34 and the recovery conveyance path 38 including the recovery screw 35 other than the both ends in the longitudinal direction below the supply conveyance path 37. In this configuration, it is sufficient to separate the developer having a lowered toner density after development from the developing sleeve 32 in the agent separation region 9 and transport it while stirring the developer in the recovery transport path 38 by the recovery screw 35. Stir and mix to achieve the desired toner density and toner charge. Then, the developer transported to the downstream end portion in the transport direction of the recovery screw 35 hits the wall of the casing and rises, and is transferred from the recovery transport path 38 to the upper supply transport path 37. The supply screw 34 supplies the developer to the developing sleeve 32 while conveying the developer in the supply conveyance path 37 in the opposite direction to the recovery screw 35.

  In the developing device of FIG. 6, only the developer that has been sufficiently stirred and mixed by the supply screw 34 is supplied to the developing sleeve 32 from the supply conveyance path 37, and the toner density immediately after passing through the developing area A is lowered. The developer is merely stirred and conveyed in the collection conveyance path 38 by the collection screw 35 and is not immediately supplied to the development sleeve 32. Therefore, only the toner having the target toner density and toner charge amount is used for the development sleeve 32, and high image quality can be obtained.

  In the developing device in which the recovery screw 35 and the supply screw 34 are arranged in the vertical direction beside the developing sleeve 32 in FIG. 6, the developer that has passed through the developing area A may be separated from the developing sleeve 32 in the agent releasing area 9. is important. This is because if the developer does not move away from the developing sleeve 32, the developer having a low toner density after passing through the developing area A is conveyed again to the developing area A, and the image density is lowered.

  The agent separation from the developing sleeve will be described. In the following explanation, the normal direction magnetic force formed on the surface of the developing sleeve by the magnetic pole included in the developing sleeve acts in the direction normal to the developer on the surface of the developing sleeve toward the center of the developing sleeve. This is called magnetic attraction, and when working in a direction away from the center, it is called normal magnetic repulsion. If the normal magnetic attraction force formed on the surface of the developing sleeve by the magnetic pole included in the developing sleeve is large, the ability of the developing sleeve to transport the developer is enhanced. On the other hand, when a normal magnetic repulsive force is formed on the surface of the developing sleeve, the developer is separated from the surface of the developing sleeve, and the agent is separated.

  6 has functions as a pumping magnetic pole N3 pole, a pre-development transport magnetic pole S2, a development magnetic pole N1, a post-development transport magnetic pole S1, and a developer separation magnetic pole N2 as shown in FIG. A developing sleeve containing five magnetic poles (hereinafter referred to as a five-pole sleeve) is used. Of these five magnetic poles, the adjacent agent separating magnetic pole N2 pole and the pumping magnetic pole N3 pole have the same polarity, so that the normal direction magnetism is applied to the developing sleeve surface between the agent separating magnetic pole N2 pole and the pumping magnetic pole N3 pole. A repulsive force is formed and the agent is separated.

  Incidentally, in recent years, there is a demand for further downsizing of the developing device even in the developing device in which two of the recovery screw 35 and the supply screw 34 are arranged beside the developing sleeve 32 of FIG. In order to realize further downsizing of the developing device, it is desirable to use a developing sleeve 32 having a small diameter. However, the five-pole sleeve employed in the developing device of FIG. 6 has a limit in reducing the space required for the arrangement of the five magnetic poles, and there is a limit in reducing the diameter of the developing sleeve.

  In Japanese Patent Application No. 2009-025834, the applicant of the present application described, “Development magnetic pole for generating a magnetic field in the development area, magnetic pole before development for transporting the developer supplied from the developer storage portion to the development area, and development. In order to release the developer after passing through the region from the surface of the developing sleeve, there are only three magnetic poles including a post-development magnetic pole that generates a magnetic field for releasing the developer from the pre-development magnetic pole. The developer is pumped up onto the surface of the developing sleeve by the magnetic field to be developed, and the development on the developing sleeve from the position where the developer is supplied from the developer accommodating portion to the developing area by the magnetic field generated by the magnetic pole before development and the developing magnetic pole. The developer is held on the developing sleeve from the developing area to the position where the developer on the surface of the developing sleeve is released by the magnetic field generated by the developing magnetic pole and the post-developing magnetic pole. It proposes a developing device "configured to perform lifting. In this developing device, by adopting a developing sleeve (hereinafter referred to as a three-pole sleeve) containing three magnetic poles, the space required for the arrangement of the magnetic poles can be reduced as compared with the five-pole sleeve, and the developing sleeve can be reduced in diameter. Can do.

  FIG. 8 is a schematic configuration diagram of a developing device in which two screws are arranged in the vertical direction and a tripolar sleeve is used. In this three-pole sleeve 32, the magnetic pole N2 that functions as the pumping magnetic pole and the magnetic pole N1 that functions as the agent separation magnetic pole also function as a pre-development transport magnetic pole and a post-development transport magnetic pole, respectively. The degree of freedom in arrangement of the N2 pole and the agent separation magnetic pole N1 pole is low. Specifically, the pumping magnetic pole N2 is disposed adjacent to the development magnetic pole S1 in order to function as a pre-development transport magnetic pole and the agent separation magnetic pole N1 as a post-development transport magnetic pole. For this reason, even if the developing sleeve 32 has a small diameter, the distance on the developing sleeve 32 between the agent separating magnetic pole N1 pole and the pumping magnetic pole N2 pole becomes wide, and a large normal line is formed between the agent separating magnetic pole N1 pole and the pumping magnetic pole N2 pole. It is difficult to generate directional magnetic repulsion.

  On the other hand, since the conventional 5-pole sleeve has the pre-development transport magnetic pole and the post-development transport magnetic pole, the pumping magnetic pole and the agent separating magnetic pole do not need to function as the transport magnetic pole. Since it only needs to be arranged so as to fulfill its original function, the degree of freedom of arrangement is high. For this reason, in the 5-pole sleeve, it is easy to arrange the agent separating magnetic pole and the pumping magnetic pole having the same polarity close to each other so as to generate a large normal magnetic repulsion force.

  Thus, since the normal magnetic repulsive force formed between the agent separating magnet and the pumping magnetic pole is small in the three-pole sleeve, the speed at which the developer leaves the developing sleeve is slow, and the developer is in the vicinity of the agent separating region. Easy to stay. When the developer stays in the agent separation area, the stayed developer may reattach to the developing sleeve. Due to this re-adhesion, the developer having a low toner density after passing through the development area is conveyed again to the development area, and the image density is lowered.

  The problem of the developer re-adhesion in the agent separation region has been described using the tripolar sleeve, but is not limited to this. For example, even in the case of a 5-pole sleeve, due to the relationship with other magnetic poles or other members, the proximity of the agent separating magnetic pole and the pumping magnetic pole to such an extent that a large normal magnetic repulsive force can be formed between the agent separating magnetic pole and the pumping magnetic pole. In the case where it is difficult to arrange them, there is a risk of occurrence in the same manner.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to collect a developer that has been separated from the developing sleeve after passing through the developing region, and to stir and transport the developer. In a small developing device in which a supply developer agitating member to be supplied to the developing sleeve is disposed in the vertical direction beside the developing sleeve, and the developer is circulated and conveyed between the recovery agitating and conveying member and the supply agitating and conveying member. It is an object of the present invention to provide a developing device, a process cartridge, and an image forming apparatus capable of preventing re-deposition of a separated developer to a developing sleeve and suppressing a decrease in image density.

In order to achieve the above object, the invention of claim 1 includes a magnetic field generating means having at least a developing magnetic pole, a pumping magnetic pole, and an agent releasing magnetic pole having the same polarity as the pumping magnetic pole, and comprises a toner and a magnetic carrier. A developing sleeve that conveys the developer by carrying the developer on the surface and moving the surface, and a magnetic field is generated in the vicinity of the region where the magnetic field is generated to pump up the developer onto the surface of the developing sleeve by the pumping magnetic pole. A developer supply agitating and conveying member that conveys the agent while stirring the agent, and a region near the region where the magnetic field for separating the developer after passing through the developing region by the pumping magnetic pole and the agent separating magnetic pole is generated; A developer recovery stirring and conveying member that conveys the developer while stirring the developer in a direction opposite to the developer conveying direction by the developer supply stirring and conveying member; A developing device that divides and conveys the developer between the developer recovery stirring and conveying member and the developer supply stirring and conveying member; The magnetic field generating means has a pumping magnetic pole and an agent separating magnetic pole arranged at intervals, and the surface of the developing sleeve is formed in a region where a magnetic field for releasing the developer from the surface of the developing sleeve is generated. And a guide member that guides the developer separated from the surface of the developing sleeve so as to promote the movement of the developer in the direction away from the vicinity of the surface of the developing sleeve.
According to a second aspect of the present invention, in the developing device of the first aspect, the guide member guides to promote a downward movement in the vertical direction due to the weight of the developer separated from the surface of the developing sleeve. It is characterized by this.
According to a third aspect of the present invention, in the developing device according to the first or second aspect, the guide member is disposed so that a gap between the guide sleeve and the developing sleeve becomes narrower toward a downstream side with respect to the surface movement direction of the developing sleeve. It is characterized by.
According to a fourth aspect of the present invention, in the developing device according to the first, second, or third aspect, the guide member is positioned on the surface of the developing sleeve so that the normal magnetic force of the agent separating magnetic pole is 0 gauss. Further, it is characterized in that it is arranged at a downstream position with respect to the rotation direction of the developing sleeve.
The invention according to claim 5 is the developing device according to any one of claims 1, 2, 3 or 4, wherein the tangent at the uppermost position of the rotation miracle of the developer collecting stirring and conveying member is the developing sleeve. It arrange | positions on the line which goes to the rotation center of this.
According to a sixth aspect of the present invention, in the developing device according to any one of the first, second, third, fourth, and fifth aspects, the guide member is provided integrally with the partition member.
According to a seventh aspect of the present invention, in the developing device according to any one of the first, second, third, fourth, fifth or sixth aspect, the magnetic field generating means has an interval of 90 ° or more between the pumping magnetic pole and the agent separating magnetic pole. It is characterized by that.
According to an eighth aspect of the present invention, in the developing device according to any one of the first, second, third, fourth, sixth, or seventh aspects, the magnetic pole of the magnetic field generating means includes the developing magnetic pole, the pumping magnetic pole, There are only three magnetic poles, the developer separating magnetic pole, and the developer on the developing sleeve is held from the position where the developer is supplied to the developing area by the magnetic field generated by the pumping magnetic pole and the developing magnetic pole, and the developing The developer on the developing sleeve is held from the developing region to the position where the developer on the surface of the developing sleeve is released by the magnetic field generated by the magnetic pole and the agent separating magnetic pole.
According to a ninth aspect of the present invention, there is provided a process cartridge in which an image carrier and a developing unit for forming a toner image on the image carrier are integrally formed and detachable from the main body of the image forming apparatus. The developing device according to any one of claims 1 to 8 is employed.
According to a tenth aspect of the present invention, there is provided an image carrier, latent image forming means for forming an electrostatic latent image on the image carrier, and the electrostatic latent image formed on the image carrier as a toner image. In the image forming apparatus including the developing unit, the developing device according to any one of claims 1 to 8 is employed as the developing unit.
The invention according to claim 11 is the image forming apparatus according to claim 10, wherein a plurality of image carriers are arranged side by side in the horizontal direction, and the toner images formed on the image carriers are superposed to obtain an image. It is characterized by.
In the present invention, since the pumping magnetic pole and the agent separating magnetic pole of the magnetic field generating means are arranged with a space therebetween, a large normal magnetic repulsive force is exerted on the developing sleeve surface between the agent separating magnetic pole and the pumping magnetic pole. Difficult to form. For this reason, the speed at which the developer separates from the surface of the developing sleeve in the agent separation region is slower than that capable of forming a large normal magnetic repulsion force, and the detached developer tends to stay. Therefore, the guide member guides the developer in the vicinity of the agent separation area to promote the movement in the direction away from the vicinity of the surface of the developing sleeve. Thereby, the stay of the developer near the agent separation region is suppressed, and the stayed developer is prevented from reattaching to the surface of the developing sleeve. Further, since the guide member is provided apart from the surface of the developing sleeve, there is no possibility that the surface property of the developing sleeve is affected or a load is applied to the driving of the developing sleeve.

  According to the present invention, the recovery agitating and conveying member that collects and conveys the developer separated from the developing sleeve after passing through the developing region, and the supply developer agitating member that supplies the developing sleeve while agitating and conveying the developer are provided. In a small development device that is placed vertically next to the developing sleeve and circulates and conveys the developer between the collected stirring and conveying member and the supply agitating and conveying member, reattachment of the developer away from the developer to the developing sleeve is prevented. Thus, there is an excellent effect that a decrease in image density can be suppressed.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 2 is a schematic configuration diagram of an image forming unit. Sectional drawing of a developer conveyance path. Explanatory drawing of the flow of the developer which separated the agent in the structure which provided the guide member. Explanatory drawing of the influence which the developer which left | separated the agent receives from the developer which flew from the collection screw. The schematic block diagram of the image development apparatus which has arrange | positioned the screw of patent document 1 2 lengthwise. FIG. 7 is an explanatory diagram of a 5-pole sleeve employed in the developing device of FIG. 6. Explanatory drawing of the 3 pole sleeve employ | adopted as the developing device of a prior application. The schematic block diagram of the developing device which has arrange | positioned two conventional screws in the horizontal direction.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of a tandem type color image forming apparatus (hereinafter, simply referred to as “image forming apparatus”) in which a plurality of photoconductors are arranged in the horizontal direction will be described.
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment.

  This image forming apparatus is provided with a transport belt 15 for transporting the transfer paper P at the center thereof. Above the conveyor belt 15, four image forming units 17K, 17M, and 17Y that form black (K), magenta (M), yellow (Y), and cyan (C) color images sequentially from the upstream side in the paper conveyance direction. , 17C are arranged side by side, so-called tandem image forming units are opposed to each other. Note that the order of colors is not limited to this. For example, black (K) may be arranged on the most downstream side, and image formation may be performed in the order of MYCK.

  The conveyor belt 15 is an endless belt that is stretched around support rollers 18 and 19, one of which is a drive roller and the other is a driven roller, and rotates in the counterclockwise direction in the figure by the rotation of the support rollers 18 and 19. To do. Below the transport belt 15, paper feed trays 20, 21, and 22 that store transfer paper P are provided.

  Each of the image forming units 17K, 17M, 17Y, and 17C includes drum-shaped photoreceptors 1K, 1M, 1Y, and 1C as image carriers. Around each of the photoreceptors 1K, 1M, 1Y, and 1C, there are a charging device, an exposure device, a developing device, a cleaning device, and the like, which will be described later.

  In addition, four transfer devices 5K, 5M, 5Y, and 5C are disposed on the inner side of the conveyance belt 15 facing the image forming units 17K, 17M, 17Y, and 17C, respectively. The transfer devices 5K, 5M, 5Y, and 5C are supplied with a transfer bias from a power source (not shown), and the toners formed on the photoreceptors 1K, 1M, 1Y, and 1C by the image forming units 17K, 17M, 17Y, and 17C. The image is transferred onto the transfer paper P that is transported to the transport belt 15. A fixing device 24 for fixing the toner image transferred onto the transfer paper P is provided on the left side of the transfer conveyance belt 15 in the drawing.

  In this image forming apparatus, at the time of image formation, for example, of the transfer paper P stored in the paper feed tray 20, the transfer paper P at the uppermost position is sent out and is temporarily put on standby by the registration roller 23. Then, the image forming units 17K, 17M, 17Y, and 17C are sent out in synchronization with the image formation, and are attracted to the transport belt 15 by electrostatic attraction. The transfer paper P attracted to the transport belt 15 is transported to the first image forming unit 17K, and the black toner image formed on the photoreceptor 1K is transferred by the transfer device 5K. The transfer paper P attracted to the transport belt 15 is transported to the next image forming unit 17M, and a magenta toner image formed on the photoreceptor 1M by the transfer device 5M is already formed on the transfer paper P. It is transferred onto the black toner image. Further, the transfer paper P is conveyed to the next image forming unit 17Y, and the yellow toner image formed on the photoreceptor 1Y by the transfer device 5Y is replaced with a black toner image or magenta toner already formed on the transfer paper P. It is transferred onto the image. Similarly, in the next image forming unit 17 </ b> C, the cyan toner image is superimposed and transferred, and a full-color superimposed image that is a four-color superimposed toner image is obtained on the transfer paper P. The transfer paper P on which the full-color superimposed image is formed in this way passes through the image forming unit 17C, is peeled off from the conveying belt 15, and then fixed by the fixing unit 24 while passing between the pair of fixing rollers. The paper is discharged to the paper discharge tray 25.

  Next, the image forming units 17K, 17M, 17Y, and 17C will be described in detail. The four image forming units 17K, 17M, 17Y, and 17C have substantially the same configuration except that they handle different colors of toner. Therefore, the subscripts are omitted and the image forming unit 17 is hereinafter omitted. Will be described.

  FIG. 2 is a schematic configuration diagram of the image forming unit 17. The image forming unit 17 includes a charging device 2, a developing device 3, a cleaning device 6, and the like around the drum-shaped photoconductor 1. In FIG. 2, the charging device 2 includes a rotating body that rotates at the same speed as the photosensitive member 1, but is not limited to the rotating body and may be a corona discharge type. The surface of the photoreceptor 1 is uniformly charged by the charging device 2 and then exposed by the writing exposure L from the exposure device 16 (not shown in FIG. 2) to form an electrostatic latent image. The developing device 3 includes a developing sleeve 32 that carries a developer 39 made of a magnetic carrier and toner that is accommodated in a developing container 31 that is a casing. An opening is formed in a part of the developing container 31, and a part of the developing sleeve 32 is disposed so as to be exposed and in close proximity to the photoreceptor 1, so that an electrostatic latent image formed on the surface of the photoreceptor 1 is formed. A developing area A where toner is supplied and development is performed is formed. The developing sleeve 32 transports the carried developer to the developing area A by moving the surface. A developing bias is applied to the developing sleeve 32 from a power source (not shown), and a developing potential that is a potential difference is formed between the electrostatic latent image on the photoreceptor 1 and the developing roller 32. The toner from the developer on the developing roller 32 is transferred to the electrostatic latent image on the photosensitive member 1 by this development potential, whereby the electrostatic latent image is developed and a toner image is formed. The toner image formed on the photosensitive member 1 moves to a transfer area facing the transfer device 5, and the toner image is transferred onto the transfer paper P conveyed by the conveyance belt 15 by the transfer device 5. In FIG. 2, the transfer paper P is not shown. In FIG. 2, the transfer device 5 is composed of a rotating body, but is not limited to a rotating body, and may be a corona discharge type. After the toner image is transferred, the photosensitive member 1 is not completely transferred onto the transfer paper P by the cleaning device 6 and is left with the toner remaining on the surface of the photosensitive member 1 to prepare for the next image forming process.

  In the present embodiment, the image forming unit 17 is in the form of a process cartridge in which the photosensitive member 1, the charging device 2, the developing device 3, and the cleaning device 6 are integrally formed. It is provided so as to be detachable from the apparatus main body.

  Next, the developing device 3 employed in the image forming unit 17 of the present embodiment will be described in detail. The developing sleeve 32 of the developing device 3 carries the developer 39 accommodated in the developing container 31 and conveys it to the developing area A for development. Inside the developing sleeve 32 is provided a magnet roller (not shown) composed of a plurality of magnets fixed to the developing device 3. Further, an agent regulating member 33 for regulating the layer thickness of the developer carried on the developing sleeve 32 is provided.

A supply screw 34 and a recovery screw 35 are provided substantially parallel to the direction of the rotation axis of the developing sleeve 32 as two conveying screws as developer agitating and conveying means. Each conveyance screw includes a rotation shaft and a wing portion spirally provided on the rotation shaft, and conveys the developer 39 in one direction along the axial direction of the rotation shaft by rotating. The interior of the developer container 31 is partitioned by an inner wall of the developer container 31 and a partition plate 36, and a supply transport path 37 and a recovery transport path 38 are formed above and below the partition plate 36 as developer transport paths. Further, openings are provided at both ends of the front and rear sides of the partition plate 36 in FIG. 2, and the supply conveyance path 37 and the collection conveyance path 38 are communicated with each other by two openings. ing.
The partition plate 36 is erected so that the end on the developing sleeve 32 side surrounds the supply screw 34, and a barrier 43 described later is formed by the erected portion. An opening is formed on the developing sleeve 32 side by the end of the barrier 43 and the inner wall of the developing device 3, and the developer 39 is supplied to the developing sleeve 32 from this opening. This opening extends in the longitudinal direction of the developing sleeve 32, and the developer 39 can be supplied to the developing sleeve 32 over the developing width.
In the developing device 3 in this embodiment, as described later, the amount of the developer 32 in the supply conveyance path 37 tends to decrease as it goes downstream, so that the end of the barrier 43 follows the phenomenon of that amount. The height of the portion is formed so as to decrease as it goes from upstream to downstream.

  As shown in FIG. 2, a supply screw 34 and a collection screw 35 are disposed in the supply conveyance path 37 and the collection conveyance path 38, respectively, and the developer 39 in the developing container 31 is supplied to the supply conveyance path 37 and the collection conveyance path 38. Is housed in. The collection screw 35 is disposed substantially parallel to the supply screw 34, and the developer 39 in the collection conveyance path 38 is conveyed by the collection screw 35 in the direction opposite to the conveyance direction of the supply screw 34. The developer 39 in the developing container 31 is circulated between the supply conveyance path 37 and the collection conveyance path 38 through openings provided at both ends of the partition plate 36 by conveyance by rotation of the supply screw 34 and the collection screw 35. To do. The supply screw 34 rotates in the clockwise direction in FIG. 2, and the recovery screw 50 rotates counterclockwise in the same manner as the developing sleeve 32.

  Of the developer 39 in the developing container 31, the developer 39 in the supply conveyance path 37 is supplied to the surface of the developing sleeve 32 while being conveyed by the rotation of the supply screw 34. The developer 39 is supplied from the supply conveyance path 37 to the developing sleeve 32 by the rotation of the supplying screw 34 over the end of the barrier 43 between the supplying screw 34 and the developing sleeve 32, or the developing sleeve 32. The developer 39 is attracted to the developing sleeve 32 by the magnetic force of a magnet roller (not shown) provided therein.

  The developer 39 supplied to the developing sleeve 32 is carried on the surface of the developing sleeve 32 by the rotation of the developing sleeve 32 and the magnetic force of an internal magnet roller (not shown), while being counterclockwise in FIG. It is conveyed in the turning direction. That is, a certain amount of the developer 39 supplied and carried on the developing sleeve 32 passes through a portion facing the agent regulating member 33 as indicated by an arrow while being carried on the developing sleeve 32. At this time, excess developer 39 out of the developer 39 carried on the surface of the developing sleeve 32 is scraped off by the agent regulating member 33 when passing through a portion facing the agent regulating member 33.

  The appropriate amount of developer 39 that has passed through the portion facing the agent regulating member 33 passes through the developing area A between the developing sleeve 32 and the photosensitive member 1, then leaves the developing sleeve 32, flows downward, and is collected and conveyed. Passed to road 38. That is, the developer 39 remaining on the developing sleeve 32 without being supplied to the surface of the photoreceptor 1 in the developing area A after being carried on the developing sleeve 32 and conveyed to the developing area A and passing through the developing area A. Instead of being collected again in the supply conveyance path 37 as the developing sleeve 32 rotates, it is once collected in the collection conveyance path 38. The collected developer 39 is conveyed in the collection conveyance path 38 while being agitated with a replenished toner, which will be described in detail later, and is delivered to the supply conveyance path 37 again. For this reason, only the developer sufficiently stirred in the collection conveyance path 38 is always present in the supply conveyance path 37.

  The developer 39 that has reached the downstream end of the supply conveyance path 37 and the developer that has passed through the development area A and separated from the surface of the developing sleeve 32 are agitated and conveyed in the collection conveyance path 38 and supplied to the supply conveyance path 37. It is handed over to the upstream end. Since the developer 39 in the collection conveyance path 38 includes the developer 32 that has passed through the development area A and has a reduced toner concentration, it is necessary to replenish the toner. Therefore, by supplying toner to the developer 39 in the collection conveyance path 38 according to the toner consumption calculated from the image information of the latent image or the measurement result of the toner density of the developer in the collection conveyance path 38, The developer 39 having an appropriate toner density can be transferred to the supply conveyance path 37.

FIG. 3 is a cross-sectional explanatory view in the vicinity of the rotation axis of the supply screw 34 when the developing device 3 is viewed from the photosensitive member 1 side in FIG. 2. The arrows in FIG. 3 indicate the flow of the developer 39 in the developing container 31. The developing device 3 is configured such that the positional relationship between the supply conveyance path 37 and the collection conveyance path 38 is aligned vertically. For this reason, of the openings provided at both ends of the partition plate 36, the developer 39 flows upward from the downstream end of the supply conveyance path 37 to the upstream end of the collection conveyance path 38 at the drop opening 42 that is the opening on the right side of FIG. Move down from. On the other hand, of the openings provided at both ends of the partition plate 36, the developer 39 flows from the bottom to the upstream end of the supply conveyance path 37 from the downstream end of the collection conveyance path 38 at the lifting port 41 that is the opening on the left side in FIG. Move up. The developer moves from the collection conveyance path 38 to the supply conveyance path 37 at the lifting port 41 so as to be pushed up from below by the pressure of the developer 39 accumulated at the downstream end in the conveyance direction in the collection conveyance path 38. Developer is delivered.
Further, in the developing device 3, as shown by an arrow T in FIG. The toner replenished in the developing container 31 by this toner replenishment can fall from the drop port 42 to the upstream end portion in the transport direction of the recovery transport path 38 and supply the developer 39 in the recovery transport path 38 with toner. .

In the developing device 3, not all of the developer 39 transferred from the recovery conveyance path 38 to the supply conveyance path 37 reaches the downstream end in the conveyance direction of the supply screw 34 in the supply conveyance path 37. There is a component that is supplied to the surface of the developing sleeve 32 while being conveyed in the supply conveyance path 37 and is collected in the collection conveyance path 38 after passing through the development region A. The delivery of the developer 39 to the surface of the developing sleeve 32 is performed over substantially the entire region of the developing sleeve 32 in the rotation axis direction. For this reason, the amount of the developer 39 that is transported with the transport force applied by the supply screw 34 in the supply transport path 37 is recovered from the surface of the developing sleeve 32 to the recovery transport path 38 as described above. As a result, there is a tendency to gradually decrease from the upstream end to the downstream end in the supply conveyance path 37.
On the other hand, the amount of the developer 39 that is transported with the transport force applied by the recovery screw 35 in the recovery transport path 38 tends to gradually increase from the upstream end to the downstream end in the recovery transport path 38. That is, there is a deviation in the distribution of the amount of the developer 39 in the developing device 3.

  In the developing device 3, the developer that has been supplied from the supply conveyance path 37 to the development sleeve 32, passes through the development region A, and has a decreased toner concentration is separated from the surface of the development sleeve 32 at a position facing the collection conveyance path 38. It is collected in the transport path 38. The developer collected in the collection conveyance path 38 is agitated in the collection conveyance path 38 with the toner replenished at the upstream end in the conveyance direction in the collection conveyance path 38, and in a state where a desired toner concentration is obtained. It is supplied to the supply conveyance path 37. As described above, in the developing device 3, the developer whose toner density has decreased after passing through the development area A is not collected in the supply conveyance path 37, and therefore, in the supply conveyance path 37 on the upstream side and the downstream side in the conveyance direction by the supply screw 39. In this case, the toner density of the developer 32 does not change.

Next, the developer carrier of the developing device 3 will be described in more detail with reference to FIG.
The developer carrier of the developing device 3 includes a developing sleeve 32 and a magnet roller 32a included therein. The magnet roller 32a generates an electric field having a strength capable of holding the developer 39 on the developing sleeve 32, and includes a magnet constituting the S1 pole as the developing magnetic pole and an N1 pole downstream of the S1 pole. And an upstream N2 pole. In this way, the number of magnets is three, and the magnetic poles for generating a magnetic field having a strength capable of holding the developer 39 on the developing sleeve 32 are arranged in the small-diameter developing sleeve 32 by using three magnetic poles. As a result, the developing sleeve 32 can be reduced in diameter. This is called a three-pole sleeve.
As the magnetic field generating means arranged in the developing sleeve 32, in addition to the method of embedding a magnet like the above-described magnet roller 32a, the peripheral surface of a cylindrical member formed by mixing magnetic powder into resin is used. It is also possible to form a magnetic pole similar to that of the above-described magnet roller 32a by performing a magnetizing process with the magnetizing yoke facing each other.

  In the developing device 3, an S1 pole that is a developing magnetic pole is disposed at a position facing the photoreceptor 1. In addition, an N2 pole that is a pre-development magnetic pole that functions as a pumping magnetic pole and a pre-development transporting magnetic pole is disposed upstream of the developing sleeve 32 in the surface movement direction with respect to the S1 pole that is the development magnetic pole, and the post-development is downstream of the surface movement direction. An N1 pole, which is a post-development magnetic pole that functions as a conveyance magnetic pole and an agent separation magnetic pole, is disposed. Thus, in the three-pole sleeve, the magnetic pole adjacent to the upstream side with respect to the development magnetic pole S1 is the pre-development magnetic pole functioning as the pumping magnetic pole and the pre-development transport magnetic pole, and the magnetic pole adjacent to the downstream side is the post-development transport magnetic pole and This is a post-development magnetic pole that functions as an agent separating magnetic pole. The N2 pole, which is a pre-development magnetic pole, also has a function as an agent regulating magnetic pole that generates a magnetic field in an agent regulating region where the developing sleeve 32 and the agent regulating member 33 face each other.

  The development magnetic pole may be the N1 pole, the pre-development magnetic pole that functions as the pumping magnetic pole and the pre-development transport magnetic pole may be the S2 pole, and the post-development magnetic pole that functions as the post-development transport magnetic pole and the agent separation magnetic pole.

  In the case of the three-pole sleeve, as described above, the pre-development magnetic pole that functions as the pumping magnetic pole and the post-development magnetic pole that functions as the agent separation magnetic pole are adjacent to the development magnetic pole. As shown in FIG. 2, on the developing sleeve 32, the N1 pole functioning as the agent separating magnetic pole and the N2 pole functioning as the pumping magnetic pole on the downstream side in the surface movement direction of the developing sleeve 32 with respect to the N1 pole functioning as the agent separating magnetic pole. Spacing increases.

Next, the agent separation in the developing device 3 will be described.
As described above, the developer 39 that has passed through the developing area A is transported to a portion of the developing sleeve 32 that faces the collection transport path 38. Thereafter, it is detached from the developing sleeve 32 in the vicinity of the agent separating portion 9. At this time, if the developer 39 does not leave the developing sleeve 32 or if the developer 39 once separated from the developing sleeve 32 is pumped up again from the inside of the collection conveyance path 38, the toner density passes through the developing area A. Since the developer 32 having a low value is conveyed again to the development area A and the image density is lowered, it is not desirable. For this reason, it is important that the agent separation is performed well in the vicinity of the agent separation portion 9.

  If the normal magnetic attractive force formed on the surface of the developing sleeve by the magnetic pole included in the developing sleeve 32 is large, the ability of the developing sleeve to convey the developer is also increased. On the other hand, when a normal magnetic repulsive force is formed on the surface of the developing sleeve, the developer is separated from the surface of the developing sleeve 32 and the agent is separated. Generally, by making the adjacent agent separating magnetic pole and the pumping magnetic pole the same polarity, a normal magnetic repulsive force is formed on the surface of the developing sleeve between the agent separating magnetic pole and the pumping magnetic pole, thereby separating the agent. ing.

  However, in the three-pole sleeve of this embodiment, the N2 pole that functions as the pumping magnetic pole and the magnetic pole N1 that functions as the agent separation magnetic pole also have the functions of the pre-development transport magnetic pole and the post-development transport magnetic pole, respectively. The degree of freedom of arrangement is low. Specifically, the pumping magnetic pole N2 and the agent separating magnetic pole N1 are arranged adjacent to the developing magnetic pole S1. For this reason, even if the developing sleeve 32 has a small diameter, the distance on the developing sleeve between the agent separating magnetic pole N1 and the pumping magnetic pole N2 is increased, and a large normal magnetic repulsive force is generated between the agent separating magnetic pole and the pumping magnetic pole. It is difficult to arrange the magnetic poles to generate

  In the three-pole sleeve, the magnetic repulsive force in the normal direction formed between the agent separating magnetic pole N1 and the pumping magnetic pole N2 is small, so that the speed at which the developer 39 is separated from the developing sleeve 32 is slow, and the developer 39 is separated from the agent. It tends to stay in the vicinity of the region 9. When the developer stays in the agent separation area 9, the stayed developer 39 may reattach to the developing sleeve 32. Due to this re-adhesion, the developer 39 having a low toner density after passing through the development area A is conveyed again to the development area A, and the image density is lowered.

  Therefore, in the developing device 3 of the present embodiment, the developer 39 separated from the developer is in a direction away from the surface of the developing sleeve 32 in the recovery stirring and conveying path 38 in the agent separating area 9 without contact with the developing sleeve 32. A guide member 46 is provided for guiding the movement downward in the vertical direction. By this guide member 46, the speed at which the developer sleeve 32 is separated from the surface of the developing sleeve 32 is slow, and the developer 39 that tends to stay in the vicinity of the agent separating area 9 is guided to promote the downward movement in the vertical direction by its own weight, thereby suppressing the stay. The developer moves downward in the vertical direction and is collected by the collection screw 35. The collection screw 35 is rotated counterclockwise as shown in FIG. 2, and the developer 39 is collected while being conveyed toward the right side in the drawing via the lower part of the collection conveyance path 38 away from the developing sleeve 32. The developer 39 in the conveyance path 38 is agitated. Thereby, it is possible to suppress the staying developer from reattaching to the developing sleeve 32. Further, since the guide member 46 is provided apart from the surface of the developing sleeve 32, there is no possibility that the surface property of the developing sleeve 32 will be adversely affected and the driving of the developing sleeve 32 may not be loaded.

  FIG. 4 is an explanatory view of the flow of the developer separated from the agent in the configuration in which the guide member 46 is provided. As shown in FIG. 4A, the developer begins to separate in the tangential direction from the position where the normal magnetic attractive force of the developing sleeve 32 becomes zero. The developer on the developing sleeve 32 is transported at substantially the same speed as the surface moving speed of the developing sleeve 32 at a position where the normal magnetic attractive force on the upstream side is large. That is, since the developer on the developing sleeve 32 is driven to rotate at a high speed similarly to the developing sleeve 32, inertia force acts on the developer. Therefore, at the position where the normal magnetic attracting force becomes zero, the developer moves away from the developing sleeve in the tangential direction using not only the weight of the developer but also the inertial force described above. Therefore, in FIG. 4, the guide member 46 is disposed at a position downstream of the rotation direction of the developing sleeve with respect to the position where the normal magnetic force of the agent separation pole N1 is 0 gauss. Accordingly, the guide member 46 is provided at a position where the developer separated from the agent tends to stay, and the staying developer can be effectively suppressed by guiding the developer that tends to stay so as to move downward in the vertical direction. Further, as shown in FIG. 4A, the guide member 46 is disposed so that the gap with the developing sleeve 32 becomes narrower toward the downstream side of the developing sleeve 32. As a result, the developer separated from the agent tends to move downward as indicated by an arrow. On the other hand, FIG. 4B shows an arrangement in which the gap with the developing sleeve 32 becomes wider toward the downstream side of the developing sleeve 32. In FIG. 4B, it is difficult to move the developer downward, and the developer is warped closer to the developing sleeve 32 side, causing reattachment. Further, the guide member 46 shown in FIG. 4A also has an effect of suppressing the entry of the developer to the downstream side.

  Further, when the rotation of the collection screw 35 is increased at a high speed in order to increase the speed of image formation, the developer stirred by the collection screw 35 jumps out in the tangential direction of the rotation trajectory of the collection screw 35 by centrifugal force. May end up. FIG. 5 is an explanatory view of the influence of the developer separated from the developer flying from the recovery screw 35. As shown in FIG. 5A, when the developer jumps from the upper part of the rotary screw 35 toward the agent separation area 9 of the developing sleeve 32 that is a tangential direction, the developer in which the developer that has popped out is retained is removed. It comes to press toward the developing sleeve 32 and further promotes the reattachment of the developer in the agent separation region 9.

  Therefore, as shown in FIG. 5B, the guide member 46 is arranged on the line where the developer protrudes from the upper part of the rotary screw 35 toward the agent separation region 9 of the developing sleeve 32 in the tangential direction. As a result, the developer jumping out of the rotating screw 35 blocks the movement toward the staying developer. The developer that has jumped out of the rotating screw 35 hits the guide member 46 as shown by the arrow in FIG. 5B and returns to the rotational locus of the lower collecting screw 35. This further suppresses re-deposition of the developer in the agent separation area 9.

  In addition, as shown in FIG. 5B, the guide member 46 is formed integrally with the partition plate 36 that divides the collection conveyance path 38 and the upper supply conveyance path 37, so that the cost and size can be reduced. .

  As mentioned above, in this embodiment, although this invention was demonstrated using the 3 pole sleeve 32, it is not restricted to this. In the case where the pumping magnetic pole and the agent separating magnetic pole are arranged with an interval of 90 ° or more, the present invention can be applied and the same effect can be obtained. For example, even in the case of a 5-pole sleeve, due to the relationship with other magnetic poles or other members, the proximity of the agent separating magnetic pole and the pumping magnetic pole to such an extent that a large normal magnetic repulsive force can be formed between the agent separating magnetic pole and the pumping magnetic pole. In the case where it is difficult to arrange them, the present invention can be applied and the same effect can be obtained.

  Further, in the present embodiment, the present invention has been described using a color image forming apparatus using a conveyance belt as a tandem type image forming apparatus that employs the developing device 3 having a reduced lateral size. It is not limited to. For example, the present invention is applicable to a color image forming apparatus using an intermediate transfer belt, and similar effects can be obtained.

As described above, according to the present embodiment, the development includes the magnet roller 32a as the magnetic field generating means having at least the developing magnetic pole S1, the pumping magnetic pole N2, and the agent separating magnetic pole N2, and is composed of toner and magnetic carrier. A developing sleeve 32 is provided that conveys the developer by carrying the developer on the surface and moving the surface. Further, a supply screw 34 as a developer supply agitating and conveying member that is arranged in the vicinity of a region where a magnetic field is generated in order to draw up the developer on the surface of the developing sleeve 32 by the drawing magnetic pole N2 and conveys the developer while stirring in the longitudinal direction. And in the vicinity of the region where the magnetic field for separating the developer after passing through the developing region A by the pumping magnetic pole N1 and the agent separating magnetic pole N1 is generated and opposite to the developer conveying direction by the supply screw 34 A collecting screw 35 as a developer collecting stirring and conveying member that conveys the developer in the direction, and a partition member 36 that partitions between the supply screw 34 and the collecting screw 35 except at both ends in the longitudinal direction. The developer is circulated and conveyed between the toner and the supply screw 34. In the magnet roller 32a, the pumping magnetic pole N2 pole and the agent separating magnetic pole N1 pole are arranged with a wide interval, and in a region where a magnetic field for separating the developer from the surface of the developing sleeve 32 is generated, A guide member 46 is provided that is spaced apart from the surface of the developing sleeve 32 and guides the developer separated from the surface of the developing sleeve 32 so as to promote the movement away from the vicinity of the surface of the developing sleeve.
Further, according to the present embodiment, the guide member 46 guides the developer so as to promote the downward movement in the vertical direction due to the weight of the developer separated from the surface of the developing sleeve 32, and the developer is efficiently developed. Movement in a direction away from the vicinity of the sleeve surface can be promoted.
The guide member 46 is arranged so that the gap with the developing sleeve 32 becomes narrower toward the downstream side in the rotation direction of the developing sleeve 32. As a result, the developer separated from the developer easily moves downward on the upstream side, and has an effect of suppressing the entry of the developer to the downstream side.
In this embodiment, the guide member 46 is positioned downstream of the developing sleeve 32 in the rotational direction with respect to the rotational direction of the developing sleeve 32 from the position where the normal magnetic force of the agent separating magnetic pole N1 is 0 gauss on the surface of the developing sleeve. Arranged. The developer carried on the developing sleeve 32 starts to separate from the position where the normal magnetic attractive force of the developing sleeve 32 becomes zero toward the tangential direction. This is because the developer on the developing sleeve 32 is conveyed at substantially the same speed as the surface movement speed of the developing sleeve 32 at a position where the normal magnetic attractive force on the upstream side is large. That is, since the developer on the developing sleeve 32 is driven to rotate at a high speed similarly to the developing sleeve 32, inertia force acts on the developer. Therefore, at the position where the normal magnetic attracting force becomes zero, the developer moves away from the developing sleeve in the tangential direction using not only the weight of the developer but also the inertial force described above. Therefore, by disposing the guide member 46 at a position downstream of the rotation direction of the developing sleeve from the position where the normal magnetic force of the agent separation pole N1 pole is 0 gauss, the developer separated from the agent By providing the guide member 46 at a position where the toner tends to stay and guiding the developer that tends to stay so as to move downward in the vertical direction, the stay can be effectively suppressed.
In the present embodiment, the guide member 46 is arranged on a line where the tangent at the uppermost position of the rotation miracle of the collection screw 35 is directed to the rotation center of the developing sleeve 32. This is because the developer stirred by the collection screw 35 may jump out in the tangential direction of the rotation trajectory of the collection screw 35 due to centrifugal force. When the developer jumps out from the upper part of the rotating screw 35 toward the developer separation region 9 of the developing sleeve 32 that is tangential, the developer staying out of the developer is pressed against the developing sleeve 32. Furthermore, the reattachment of the developer in the agent separation region 9 is promoted. Therefore, by arranging the guide member 46 on the above line, the developer jumping out of the rotary screw 35 is blocked from moving toward the staying developer. This further suppresses re-deposition of the developer in the agent separation area 9.
In the present embodiment, the guide member 46 is formed integrally with the partition plate 36 that partitions the collection conveyance path 38 and the upper supply conveyance path 37, whereby cost reduction and miniaturization can be achieved.
Further, in the present embodiment, the magnet roller 32a included in the developing sleeve 32 is not limited to the three-pole sleeve as long as the magnetic pole drawn up by the magnet roller and the magnetic pole away from the agent are disposed at an interval of 90 ° or more. The above problem occurs even with a 5-pole sleeve. Therefore, by applying the present invention, it is possible to prevent re-deposition of the developer separated from the developer onto the developing sleeve and suppress a decrease in image density.
In the present embodiment, the magnet roller 32a included in the developing sleeve 32 has only three magnetic poles: a developing magnetic pole S1, a pumping magnetic pole N2, and an agent separating magnetic pole N1, and a pumping magnetic pole N1. The developer on the developing sleeve 32 is held from the position where the developer is supplied to the developing region by the magnetic field generated by the developing magnetic pole S1 pole, and the developing is performed by the magnetic field generated by the developing magnetic pole S1 pole and the agent separating magnetic pole N1 pole. The developer on the developing sleeve is held from the region to the position where the developer on the surface of the developing sleeve is released. In the developing sleeve 32 of such a three-pole sleeve, the N2 pole that functions as the pumping magnetic pole and the magnetic pole N1 that functions as the agent separation magnetic pole also have the functions of the pre-development transport magnetic pole and the post-development transport magnetic pole, respectively. Therefore, the degree of freedom of arrangement is low. Specifically, the pumping magnetic pole N2 and the agent separating magnetic pole N1 are arranged adjacent to the developing magnetic pole S1. For this reason, even if the developing sleeve 32 has a small diameter, the distance on the developing sleeve between the agent separating magnetic pole N1 and the pumping magnetic pole N2 is increased, and a large normal magnetic repulsive force is generated between the agent separating magnetic pole and the pumping magnetic pole. It is difficult to arrange the magnetic poles to generate Therefore, the developer tends to stay in the agent separation region, and the stay can be effectively suppressed by the present invention.
In addition, according to the present embodiment, maintainability can be improved by forming the photosensitive member 1 and the developing device 3 integrally and making the process cartridge removable from the image forming apparatus main body.
In addition, a developing device 3 having a reduced horizontal size is used as a tandem type image forming apparatus in which a plurality of photoconductors are arranged in the horizontal direction and toner images formed on the photoconductors are superimposed to obtain an image. It can be adopted and a high quality image can be obtained.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging device 3 Developing device 5 Transfer device 15 Conveying belt 31 Developing container 32 Developing sleeve 32a Magnet roller 33 Restricting member 34 Supply screw 35 Recovery screw 36 Partition plate 37 Supply conveying path 38 Recovery conveying path 39 Developer 43 Barrier 46 Guide member

JP 2003-263012 A

Claims (11)

A developer that includes at least a developing magnetic pole, a pumping magnetic pole, and a magnetic field generating means having an agent separating magnetic pole that is the same as the pumping magnetic pole, and carries the developer composed of toner and magnetic carrier on the surface and moves the developer. A developer sleeve that conveys the developer, and a developer supply agitating and conveying member that is arranged in the vicinity of a region where a magnetic field is generated to pump the developer onto the surface of the developing sleeve by the pumping magnetic pole and conveys the developer in the longitudinal direction, The pumping magnetic pole and the agent separating magnetic pole are disposed in the vicinity of a region where a magnetic field for releasing the developer after passing through the developing region is generated, and the direction opposite to the developer conveying direction by the developer supply stirring and conveying member The developer recovery stirring and conveying member that conveys the developer while stirring, the developer supply stirring and conveying member, and the developer recovery stirring and conveying member between the two ends in the longitudinal direction. In the developing apparatus for circulating conveying the developer between a partition member, a developer recovery stirring and conveying member and the developer supplying stirring and conveying member for partitioning, the
The magnetic field generating means has a pumping magnetic pole and an agent separating magnetic pole arranged at intervals, and the developing sleeve surface and a region where the magnetic field for releasing the developer from the developing sleeve surface is generated. A developing device comprising a guide member that guides the developer separated from the surface of the developing sleeve so as to promote movement in a direction away from the vicinity of the surface of the developing sleeve.   The developing device according to claim 1, wherein the guide member guides to promote downward movement in the vertical direction due to the weight of the developer separated from the surface of the developing sleeve.   3. The developing device according to claim 1, wherein the guide member is disposed so that a gap between the guide member and the developing sleeve becomes narrower toward a downstream side with respect to a surface movement direction of the developing sleeve.   4. The developing device according to claim 1, wherein the guide member is rotated in a direction in which the developing sleeve rotates relative to a position where the normal magnetic force of the agent separating magnetic pole is 0 gauss on the surface of the developing sleeve. The developing device is arranged at a position downstream of the developing device.   5. The developing device according to claim 1, wherein the guide member is disposed on a line in which a tangent at the uppermost position of the rotation miracle of the developer recovery stirring and conveying member is directed to the rotation center of the developing sleeve. A developing device.   6. The developing device according to claim 1, wherein the guide member is provided integrally with the partition member.   7. The developing device according to claim 1, wherein the magnetic field generating means has a spacing between the pumping magnetic pole and the agent separating magnetic pole of 90 [deg.] Or more. apparatus.   8. The developing device according to claim 1, wherein the magnetic field generating means has three magnetic poles: the developing magnetic pole, the pumping magnetic pole, and the agent separating magnetic pole. The developer on the developing sleeve is held from the position where the developer is supplied to the developing area by the magnetic field generated by the pumping magnetic pole and the developing magnetic pole, and the developing magnetic pole and the agent separating magnetic pole are generated. A developing device configured to hold a developer on a developing sleeve from a developing region to a position where the developer on the surface of the developing sleeve is released by a magnetic field.   9. The developing device according to claim 1, wherein an image carrier and a developing unit for forming a toner image on the image carrier are integrally formed and detachable from the main body of the image forming apparatus. A process cartridge characterized by adopting.   An image having an image carrier, a latent image forming unit for forming an electrostatic latent image on the image carrier, and a developing unit for converting the electrostatic latent image formed on the image carrier into a toner image 9. An image forming apparatus according to claim 1, wherein said developing means employs the developing device according to claim 1.   11. The image forming apparatus according to claim 10, wherein a plurality of image carriers are arranged side by side in a horizontal direction, and each toner image formed on each image carrier is superimposed to obtain an image.

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