JP2016206647A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device that prevents or suppresses a toner from leaking to the outside of a developing device and prevents or suppresses contamination of peripheral equipment and recording media by a leaked toner.SOLUTION: There is provided a developer device 1 comprising a rotatable developer carrier 2 that supplies, to a photoreceptor drum 10, a developer napped on its surface by a magnetic force, and capable of recovering a floating toner that is a floating developer into the inside of a housing 1A with a peripheral airflow generated during an operation or rotation of the developer carrier 2, wherein an opposing interval G1 between an inner wall 1A2 of the housing and a surface of the developer carrier 2 is made larger in a magnetization area P1 where the developer is napped than on the outside of the magnetization area P1 in a longitudinal direction X of the developer carrier 2.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a developing device, a process cartridge, and an image forming apparatus.

An image forming apparatus using an electrophotographic system may include a developing device that uses a two-component developer including toner and a carrier in addition to a toner-only one-component developer.
A developing device using a two-component developer uses, for example, a developer carrier having a plurality of built-in magnetic poles, a magnetic brush of developer is raised on the surface, and the toner in the magnetic brush is transferred to the latent image carrier. The image is transferred to the electrostatic latent image formed on the surface, and visible image processing is performed.

The magnetic brush formed on the surface of the developer carrying member may contain uncharged toner that does not have a charge amount enough to be electrostatically attached to the carrier, and the uncharged toner is present around the developing device. May float and contaminate peripheral devices and recording media.
As a configuration for collecting floating uncharged toner, a configuration in which uncharged toner is taken into the developing tank using a suction airflow generated when the magnetic brush moves along the inner wall of the developing tank (for example, [Patent Document 1] Have been proposed).

  However, in the developing device, generally, the internal pressure is likely to increase due to the above-described suction airflow and rotation of blades such as a conveyance screw built in as a conveyance member. When blowout occurs outside the developing device due to the increased internal pressure, not only uncharged toner but also toner built in the developing device may leak out of the developing device and contaminate peripheral devices and recording media.

  An object of the present invention is to provide a developing device that prevents toner from leaking outside the developing device and prevents contamination of peripheral devices and recording media outside the developing device due to the leaked toner.

  In order to achieve this object, the present invention includes a developer carrier that can be rotated by the magnetic force on the surface of the developer, and the floating toner is fed into the developer tank by the peripheral airflow generated when the developer carrier rotates. In the developing device to be collected, the facing interval between the inner wall of the developing tank and the surface of the developer carrying member is larger than the facing interval of the magnetized region where the developer spikes in the longitudinal direction of the developer carrying member. The developing device has a narrower facing distance outside the magnetized region.

  According to the present invention, it is possible to prevent toner from leaking out of the developing device, and to prevent contamination of peripheral devices and recording media outside the developing device due to the leaked toner.

It is a schematic diagram explaining an example of the developing device concerning this invention. It is sectional drawing which shows the detail of the image development apparatus shown in FIG. It is a schematic diagram for demonstrating the airflow which arises in the image development apparatus shown in FIG. FIG. 2 is a view for explaining each region in a longitudinal direction of a developer carrier provided in the developing device shown in FIG. 1. FIG. 3 is a partially enlarged view of the configuration shown in FIG. 2. It is a perspective view for demonstrating arrangement | positioning of a sealing member corresponding to arrangement | positioning of the space | interval adjustment member shown in FIG. It is a perspective view which shows the installation state of the space | interval adjustment member and sealing member which were shown in FIG. It is a figure which shows the state which looked at the installation state of the space | interval adjustment member and sealing member shown in FIG. 7 from the latent image carrier side. It is a schematic diagram which shows an example of the image forming apparatus using the developing device shown in FIG. It is a perspective view for demonstrating the problem of the conventional process cartridge.

The developing device 1 according to the present invention shown in FIGS. 1 and 2 is mounted and accommodated together in a housing of a process cartridge 20 together with a photosensitive drum 10 as a latent image carrier. The process cartridge 20 includes a developing device 1, a photosensitive drum 10, a charging device 11 disposed around the photosensitive drum 10, and a cleaning device 12, and is used for image forming processing.
FIG. 9 shows an image forming apparatus 100 according to the present invention. The process cartridge 20 is detachably attached to the main body of the image forming apparatus 100. As a result, the process cartridge 20 is taken out from the main body of the image forming apparatus 100 to the outside as the process cartridge 20 when a member provided therein reaches the end of its life. The exchangeability improves the operability of the exchanger.

As shown in FIGS. 1 and 9, the photosensitive drum 10 is charged uniformly by the charging device 11 and written by a writing device (for the sake of convenience, writing light is indicated by L) in the process of rotating in the direction of the arrow in the drawing. The latent image formation and the visible image processing of the latent image by the developing device 1 are respectively performed.
A visible image, so-called toner image, formed on the photosensitive drum 10 is transferred to a recording medium S such as recording paper by a transfer device 13 shown in FIGS. In both figures, an apparatus that is disposed adjacent to the transfer apparatus 13 and indicated by reference numeral 14 is a charger that electrostatically separates the recording medium S from the photosensitive drum 10.

  The image forming apparatus 100 shown in FIG. 9 is a direct transfer type that directly transfers the toner image on the photosensitive drum 10 to the recording medium S. However, in the indirect transfer type image forming apparatus, the toner image is It is transferred from the latent image carrier to the intermediate transfer member, and further transferred to the recording medium. The intermediate transfer member is a member used when, for example, a plurality of color toner images are superimposed and transferred in an indirect transfer type image forming apparatus such as a color image forming apparatus, and collectively transfers the superimposed images onto a recording medium.

The untransferred toner and residual charges remaining on the photosensitive drum 10 after the transfer are removed by the cleaning device 12.
The cleaning device 12 includes a cleaning blade 12 </ b> A that can recover untransferred toner from the photosensitive drum 10, and a recovery screw 12 </ b> B that is disposed in a recovery path that conveys the recovered toner toward the developing device 1. When uncharged toner and paper dust that cannot be used for development are mixed, the collected toner may be conveyed toward a waste tank.

The developing device 1 is disposed so as to face the photosensitive drum 10, and is provided with a rotatable developer carrier 2 that supplies toner in the developer, which is raised on the surface by magnetic force, to the photosensitive drum 10. It is provided inside the formed housing 1A. The specific internal configuration of the developer carrier 2 is the same as that shown in FIG.
As illustrated in FIG. 2, the housing 1 </ b> A includes a pair of spaces partitioned in the horizontal direction by a partition wall 1 </ b> A <b> 1 provided below the developer carrier 2. Of the pair of spaces, a developer supply screw 3 is provided in a space directly below the developer carrier 2, and a developer recovery screw 4 is provided in a space adjacent to the space where the developer supply screw 3 is disposed in the horizontal direction. , Each is arranged.

  The pair of spaces are provided when a pair of screws having different functions are provided, but depending on the type of the developing tank, the space may be partitioned not only in the horizontal direction but also in the oblique direction or the vertical direction. .

Of the developer supply screw 3 and the developer recovery screw 4 having different functions, the developer supply screw 3 is a member capable of supplying and transporting the developer facing the developer carrying member 2. The collection screw 4 is a member capable of conveying the developer.
The developer carrier 2, the developer supply screw 3, and the developer recovery screw 4 are provided such that the direction orthogonal to the paper surface of FIG. 2 is an axial direction corresponding to the longitudinal direction.

The partition wall 1A1 has notches at positions corresponding to both ends in the longitudinal direction of the developer supply screw 3 and the developer recovery screw 4, and a pair of spaces communicate with each other at the positions of the notches.
The developer supply screw 3 and the developer recovery screw 4 have spiral blades formed on the outer periphery of the shaft. The developer supply screw 3 and the developer recovery screw 4 are set so that the rotation directions are opposite to each other when the spiral blades are formed in the same direction, and the spiral blades are formed in opposite directions. In some cases, the rotation direction is set to the same direction. In the present embodiment, the rotation direction is set to the same direction.
As a result, in the housing 1A, the developer is conveyed in the opposite directions along the axial direction in the pair of partitioned spaces, and the developer enters the other space from each notch of the partition wall 1A1. Developer circulates.

  In the developing device 1, when the developing device 1 is operating, that is, when the developer carrier 2 is rotating, the surface of the developer carrier 2 that has passed through the development region where the developer carrier 2 and the photosensitive drum 10 face each other is placed on the surface. The standing magnetic brush moves along the inner surface of the housing 1A. The floating airflow that is likely to float due to insufficient charging between the developer carrier 2 and the photosensitive drum 10, particularly in the rotation direction of the developer carrier 2, due to insufficient charging on the downstream side of the development region due to the surrounding airflow generated at this time. Toner, in particular, uncharged toner is collected in the housing 1A. The peripheral airflow not only collects uncharged toner outside the developing device 1 but also has a function of preventing or suppressing the toner stored in the developing device 1 from inadvertently leaking outside the developing device 1. .

The ambient airflow for collecting the uncharged toner in the housing 1A is generated as follows. As shown in FIG. 3, the ambient air is sucked in by the suction of air generated on the upstream side in the direction in which the magnetic brush of the developer T standing on the surface of the developer carrier 2 moves along the inner wall 1A2 of the housing 1A. The surrounding airflow is generated by flowing. In FIG. 3, the state in which the ambient air flows is indicated by a broken-line arrow, and the broken-line arrow represents the ambient airflow Aa generated by the intake of the ambient air.
The uncharged toner is put on the peripheral airflow Aa flowing into the housing 1A, so that the uncharged toner is sucked into the housing 1A and the developer is prevented or suppressed from leaking to the outside of the developing device 1. Prevents or suppresses contamination of peripheral devices and recording media caused by

3 is located outside the magnetized region P1 (see FIG. 4) in the longitudinal direction X of the developer carrier 2 and the magnetized region P1, and the end of the developer carrier 2 The strength is different from that of the rotation support portion having the rotation support shaft. In FIG. 4, a symbol X indicates a longitudinal direction that coincides with the axial direction of the developer carrier 2. The longitudinal direction X coincides with the direction perpendicular to the paper surface of FIGS. 1 to 3, 5, and 9, and coincides with the longitudinal directions of the developer supply screw 3 and the developer recovery screw 4. In FIG. 5, the longitudinal direction X is indicated by a solid black double circle.
In the magnetized region P1 of the developer carrier 2 in the longitudinal direction X, the peripheral airflow that flows into the housing 1A according to the movement of the magnetic brush by the formation of the magnetic brush, that is, the suction airflow Ab shown in FIG. The air volume is large and the strength (wind pressure) is also strong.
On the other hand, in the rotation support portion at the end, it is difficult for the outside air to be taken in by the magnetic brush, and when the outside air taken in the magnetized region P1 flows in, the accumulated air is pushed out of the housing 1A. When air accumulated in the magnetized region P1 side in the housing 1A is pushed out to the rotation support portion side, as shown in FIG. 10, there is a possibility of a blowout air flow B in which air blows out from the housing 1A outside the magnetized region P1. There will be a certain place.

In order to prevent air from blowing out on the end side in the axial direction of the developer carrier 2, the developing device 1 of the present embodiment has an air hole that communicates the space at the end in the longitudinal direction X with the outside. It is provided in the housing 1A (see FIG. 4) above the recovery screw 4. The air hole is provided with a filter for preventing uncharged toner from leaking outside through the air hole.
In general, when a filter is provided, if the filter is clogged over time, the inflow of air is suppressed. In the developing device 1, as in the case shown in FIG. 10, there is a force for air to blow out of the developing device 1 from the end in the longitudinal direction X of the developer carrier 2, that is, from the outside of the magnetized region P <b> 1. Can occur. When the air blows out of the developing device 1, the toner accumulated in the housing 1 </ b> A blows out of the developing device 1, and the toner floating outside the developing device 1 is not collected.

In the developing device 1 in FIG. 4, in order to prevent or suppress the generation of an air current that tries to blow out from the developing device 1 from the region outside the magnetized region P1 in the longitudinal direction X (the region indicated by reference numeral P2 in FIG. 4). The following configuration is adopted. That is, a configuration is employed in which the reduction in the air intake effect in the region P2 is prevented or suppressed.
Specifically, as shown in FIG. 5, the portions of the housing 1 </ b> A facing the developer carrier 2 at positions corresponding to both ends in the longitudinal direction X of the developer carrier 2, that is, in the region P <b> 2, respectively. A configuration in which the interval adjusting member 5 is provided is employed.
The surface of the spacing adjustment member 5 that faces the developer carrier 2 is located along with the position of the housing 1A where the spacing adjustment member 5 is not provided, that is, the surface of the housing 1A that faces the developer carrier 2 in the magnetized region P1. An inner wall 1A2 is formed.

Due to the thickness T1 of the distance adjusting member 5, the facing distance G1 between the surface of the developer carrier 2 and the inner wall 1A2 in the region P2 formed by the distance adjusting member 5 is the magnetization of the surface of the developer carrier 2 and the housing 1A. It is narrower than the facing interval G2 with the inner wall 1A2 in the region P1. Specifically, as shown in FIG. 5, the relationship is G1 <G2, G2-G1 = T1, and the region P2 shown in FIG. 4 is a narrow gap region.
The facing gap G2 is set to a gap at which a necessary minimum suction airflow strength is obtained to prevent or suppress the toner in the housing 1A from leaking out of the developing device 1. The facing interval G1 is set to an interval that obtains the strength of the suction airflow that prevents or suppresses the leakage of the toner in the housing 1A to the outside of the developing device 1 more than the facing interval G2.

In the region P2, unlike the magnetized region P1, air suction is less likely to occur due to the movement of the magnetic brush. However, the relationship of G1 <G2 prevents or suppresses the air pushed out from the magnetized region P1 in the housing 1A from being blown out of the developing device 1 from the region P2.
In the region P2, the air suction strength due to the movement of the magnetic brush is weaker than in the magnetized region P1, so that the uncharged toner that has entered the housing 1A is likely to leak to the outside again. However, by setting the relationship of G1 <G2 and increasing the suction airflow (wind speed) due to the rotation of the developer carrier 2 itself in the region P2, a state in which the toner in the housing 1A is difficult to leak out of the developing device 1 can be obtained. .

More specifically, since the facing distance G1 is narrower than the facing distance G2 by the thickness T1 of the distance adjusting member 5, the distance P1 in the region P2 that is the gap narrowing region in which the facing distance G1 is set in the longitudinal direction X. Airflow speed (wind speed) increases. Therefore, the suction air flow from the outside of the developing device 1 to the inside of the housing 1A due to the rotation of the developer carrier 2 itself is locally strengthened in the region P2, and the toner in the housing 1A including the uncharged toner once sucked into the housing 1A. Maintain a state where leakage is prevented or suppressed.
As shown in FIG. 4, in the longitudinal direction X, the magnetized region P1 includes the sheet passing region P0 and is provided to the outside of the sheet passing region P0. Therefore, in the sheet passing area P0, a suction airflow by the magnetic brush is reliably obtained, and the blowout of toner to the outside of the developing device 1 is highly suppressed or prevented. Therefore, the contamination of the recording medium S due to the spraying of toner on the recording medium S passing through the paper passing area P0 to the outside of the developing device 1 is highly suppressed or prevented.

In the magnetized region P1, since the suction airflow is reliably generated using a magnetic brush, unlike the region P2, it is not necessary to increase the airflow by narrowing the facing gap G2. For this reason, the facing interval G2 is set to be larger than the facing interval G1 to such an extent that suction of uncharged toner in the housing 1A and blowing out of the toner to the outside of the developing device 1 are prevented or suppressed (FIG. 4, FIG. 4). G1 <G2 shown in FIG. 5). Therefore, the pressure of the suction airflow in the magnetized region P1 is weaker than that in the region P2, and the pressure of the air pushed from the magnetized region P1 to the region P2 in the housing 1A is also reduced. Moreover, the total amount of air per time sucked into the housing 1A over the magnetized region P1 and region P2 is also suppressed. Therefore, the pressure and volume of the air sucked into the housing 1A are suppressed throughout the longitudinal direction X, and clogging of the filter is suppressed.
As described above, in FIG. 4, the magnetized region P1 is set to correspond to the setting range of the facing interval G2 shown in FIG. 5, and the region P2 is set to correspond to the setting range of the facing interval G1 shown in FIG.

  As the thickness T1 is increased, the interval adjusting member 5 narrows the facing interval G1 to increase the strength of the suction airflow, but the passage cross-sectional area of the suction airflow decreases. If the cross-sectional area of the suction airflow is small, uncharged toner that cannot enter the housing 1A is generated depending on the amount of uncharged toner collected by the suction airflow. Uncharged toner that cannot enter the housing 1 </ b> A is accumulated outside the developing device 1 around the interval adjusting member 5, and overflows from the facing interval G <b> 1 of the interval adjusting member 5.

Therefore, the gap adjusting member 5 is composed of an elastic member that can be elastically deformed in accordance with the pressing force when the uncharged toner passes through the facing gap G1 within the relationship of G1 <G2. The elastic deformation is larger than that of the housing 1A when passing through the facing gap G2.
The interval adjusting member 5 is made of urethane foam, and can be elastically deformed according to the force pressed by the uncharged toner or developer that is in contact with the gap adjusting member 5. The interval G1 is expanded.
For example, the elasticity and hardness of the interval adjusting member 5 are experimentally adjusted so as to have the flexibility of causing the deformation to pass by the velocity of the suction air flow obtained from the facing interval G1 and the collision force when a predetermined amount of toner collides. It is desirable to use and set.
The elasticity and hardness of the gap adjusting member 5 can be changed depending on the foaming degree of the urethane foam.

  When an elastic member is used for the gap adjusting member 5, the opposing gap G1 is widened by the pushing force of the uncharged toner sucked into the housing 1A by multiplying the sucked air flow in the region P2, so that the uncharged toner can pass therethrough. . As a result, coupled with the fact that the suction airflow is locally increased in the region P2, it is possible to suppress or prevent the uncharged toner from being taken into the housing 1A even if G1 <G2.

The interval adjusting member 5 is a surface on which an inner wall 1A2 is formed so as to suppress or prevent the movement of uncharged toner or developer taken into the housing 1A from being obstructed by contact with the interval adjusting member 5. The surface roughness is set. In other words, the space adjusting member 5 has a surface roughness on which the surface forming the inner wall 1A2 has a smoothness that allows the uncharged toner or developer to slide. In other words, the uncharged toner faces the surface. The surface roughness that provides smoothness from the housing 1A when passing through the gap G2 is set.
The surface roughness of the interval adjusting member 5 is set with the intention that the movement of the uncharged toner passing through the facing interval G1 is less likely to be inhibited. The smaller the surface roughness, the higher the smoothness. The sliding resistance between the uncharged toner and the interval adjusting member 5 is reduced. “Sliding” means sliding and “sliding resistance” means resistance generated when rubbing in a sliding state.

Such setting of the surface roughness makes it easier for the uncharged toner and developer in contact with the surface of the interval adjusting member 5 forming the inner wall 1A2 to slide. For this reason, even if the contact area between the space adjusting member 5 and the uncharged toner increases due to the elastic deformation of the space adjusting member 5, the resistance to the flow of the uncharged toner into the housing 1A is reduced. Accordingly, the setting of the surface roughness and the elastic deformation of the interval adjusting member 5 improve the ability to take in uncharged toner into the housing 1A. Further, since the sliding resistance of the uncharged toner is reduced and the sliding of the uncharged toner is smoothed, deterioration due to wear of the surface forming the inner wall 1A2 in the interval adjusting member 5 is suppressed.
In setting the surface roughness of the surface forming the inner wall 1A2 in the interval adjusting member 5, not only importance is attached to the sliding of the uncharged toner, but other factors, for example, the fluid dynamics of the airflow contacting the surface It is also possible to decide in consideration of the characteristic. The facing distance G1 may be set depending on the shape of the housing 1A itself. However, if the facing distance G1 is set using the distance adjusting member 5 which is a separate member from the housing 1A, elasticity and / or surface roughness and There is an advantage that the facing interval G1 can be set relatively easily.

As shown in FIGS. 5 to 7, the developing device 1 is disposed corresponding to the region P <b> 2 and includes a sealing member 6 for blocking air that may be blown out of the housing 1 </ b> A forming the developing tank from the region P <b> 2. I have.
The sealing member 6 is formed of a plate material made of PET (polyethylene terephthalate) having bending rigidity. As shown in FIG. 6, the sealing member 6 includes a pair of end sealing portions 6 </ b> A located on both sides in the longitudinal direction X of the developer carrier 2 and a single portion connecting the end sealing portions 6 </ b> A. And a longitudinal sealing portion 6B.
As shown in FIG. 8, the end sealing portion 6 </ b> A is disposed at the installation position of the interval adjusting member 5 provided as a pair in the longitudinal direction X of the developer carrier 2. That is, the end sealing portion 6A covers the outside of the developer carrier 2, specifically, the upper portion of the developer carrier 2 as shown in FIG. Has been placed.
In the end sealing portion 6A, the tip of the end sealing portion 6A on the interval adjusting member 5 side is positioned above the interval adjusting member 5 so as not to hinder the flow of the suction airflow Ab (see FIG. 7) in the region P2. They are arranged so as to have an interval (see FIGS. 5 and 7). The end sealing portion 6 </ b> A functions as a sealing portion for sealing air blown out of the developing device 1 when air that is about to blow out from inside the developing device 1 hits.
As shown in FIG. 5, the longitudinal sealing portion 6 </ b> B is used as a portion that shields a part of the peripheral surface of the developer carrier 2 from the photosensitive drum 10. As a result, the longitudinal sealing portion 6B seals the air flow from the developing device 1 side to the photosensitive drum 10 and prevents the toner floating from the developing device 1 side from adhering to the photosensitive drum 10. prevent.

  As shown in FIG. 9, the image forming apparatus 100 accommodates the developing device 1 having the above-described configuration in the image forming unit at the substantially center in the vertical direction inside the housing 100 </ b> A. The process cartridge 20 shown in FIG. The image forming apparatus 100 includes a single process cartridge 20 so that a monochrome image can be formed. The image forming apparatus 100 includes a paper feeding device 101 below the process cartridge 20 and a document scanning unit 102 above the process cartridge 20.

The paper feeding device 101 includes a cassette 101A on which recording media S can be stacked, a feeding roller 101B, a feeding roller 101C, and a registration roller 101D disposed in front of the transfer position.
The document scanning unit 102 includes a movable mirror 102B that optically scans a document mounted on the document placement table 102A, a condensing lens 102C, and a reading element 102D.

  The toner image formed on the photosensitive drum 10 in the process cartridge 20 is transferred to the recording medium S fed out from the paper feeding device 101. The recording medium S onto which the toner image has been transferred is fixed on the toner image by the fixing device 103 and then discharged onto a paper discharge tray 100A1 provided on the housing 100A.

  The image forming apparatus according to the present invention is intended for forming a monochrome image. However, a plurality of process cartridges including the developing device 1 according to the present invention can be provided according to the number of image forming colors. In this case, the toner images formed in each process cartridge are sequentially transferred to the intermediate transfer member to form a superimposed image, and then transferred onto the recording medium at a time.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to this specific embodiment, Unless it is specifically limited by the above-mentioned description, this invention described in the claim is described. Various modifications and changes are possible within the scope of the gist of the invention.
For example, as a narrow space region, not only the outside of the magnetized region but also the outside including the end of the magnetized region can be used to increase the suction airflow in a region where the influence of the magnetic brush becomes unstable. Is possible. Further, as a method for strengthening the suction airflow, it is also possible to use suction air supply for urging suction of uncharged toner into the developing tank on the premise of setting a narrow interval. Further, the interval adjusting member does not have to be an elastic member, and when the interval adjusting member is an elastic member, the material is not limited to urethane foam, and may be, for example, a plate-like member that can be bent and deformed.
The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

DESCRIPTION OF SYMBOLS 1 Developing apparatus 1A Housing (an example of a developing tank)
1A2 Inner wall of housing (example of inner wall of developer tank)
2 Developer carrying member 5 Interval adjusting member 6 Sealing member 10 Photosensitive drum (an example of a latent image carrier)
20 Process cartridge 100 Image forming apparatus Aa Ambient airflow Ab Suction airflow B Blowout airflow G1 Opposite spacing outside the magnetized area G2 Opposed spacing in the magnetized area P0 Paper passing area P1 Magnetized area P2 Area outside the magnetized area X Longitudinal direction of developer carrier

JP 2004-252193 A

Claims (9)

In a developing device that includes a developer carrying member that can be rotated by magnetic force on the surface by a magnetic force, and collects floating toner in a developing tank by a peripheral airflow generated when the developer carrying member rotates.
The distance between the inner wall of the developer tank and the surface of the developer carrier is greater than the distance between the magnetized areas where the developer spikes in the longitudinal direction of the developer carrier. Development device with narrower facing distance.   The developing device according to claim 1, wherein the magnetized area in the longitudinal direction is wider than the sheet passing area.   The developing device according to claim 1, wherein the facing interval outside the magnetized region in the longitudinal direction is narrowed by an interval adjusting member.   The developing device according to claim 3, wherein the gap adjusting member is an elastic member that is elastically deformed.   5. The developing device according to claim 3, wherein a surface of the gap adjusting member that faces the developer carrying member has a surface roughness that provides smoothness more than an inner wall of the developing tank.   The developing device according to claim 1, wherein a sealing member is provided corresponding to a position where the facing interval is narrow in the longitudinal direction.   7. The development according to claim 6, wherein the sealing member is disposed so as to cover the outside of the developer carrier at a position corresponding to an installation position of the interval adjusting member in the longitudinal direction. apparatus. A process cartridge capable of accommodating the developing device according to any one of claims 1 to 7,
A process cartridge comprising at least the developing device and a latent image carrier. An image forming apparatus comprising the process cartridge according to claim 8,
An image forming apparatus comprising a plurality of process cartridges according to the number of image forming colors.

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