JP2014089337A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of reliably preventing a developer from leaking out of a junction between casings.SOLUTION: A side seal 66 for preventing a developer from leaking out of a developer tank is provided on an end in a longitudinal direction of a developer carrier 60 at a position where vertical division type casings 61 and 62 are butted against each other. A sheet-like seal member 67 formed of a flexible resin is arranged between the side seal 66 and the surface of one 62 of the casings on the upstream side of a layer thickness regulating member 65 in a direction of movement of a developer on the developer carrier 60. The sheet-like seal member 67 is integrally formed with the surface of the casing 62 with a base end 67A being positioned at least between the side seal 66 and the surface of the casing 62 facing the side seal 66, and a tip 67B is extended fluttering along the surface of the developer carrier 60.

Description

  The present invention relates to a developing device, a process cartridge, and an image forming apparatus, and more particularly to a structure for preventing scattering of a two-component developer.

  In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a printing machine, an electrostatic latent image formed on a photosensitive member, which is a latent image carrier, is processed with a developing device, and the visible image is processed into a sheet. A recording output can be obtained by transferring to the recording medium.

In the developing device, toner that is charged fine particles is used as a developer, and this toner is electrostatically attached to an electrostatic latent image to form a visible image.
Examples of the developer containing toner include a two-component developer mixed with a magnetic material such as iron powder.
The two-component developer moves in a state of being raised on the surface by the magnetic force from the magnetic field generating means provided in the developer carrier, but the layer thickness, so-called carrying amount, is regulated by the layer thickness regulating blade. The

  The layer thickness regulating blade is disposed so as to extend in the width direction which is a direction orthogonal to the moving direction of the developer moving along the circumferential direction on the surface of the developer carrying body, and the surface of the developer carrying body Are arranged with a predetermined gap between them.

By the way, the developer carrying member facing the area outside the image forming area on the photosensitive member used as the latent image carrying member is not provided with a magnetic field generating means because it is not necessary to carry the developer. There is.
For this reason, if a part of the developer moved on the developer carrying member is moved by being pushed toward the end of the developer carrying member, the magnetic field is generated. There is a risk of leakage to the periphery because the magnetic restraint by the means is not achieved.

Conventionally, as a configuration for preventing the leakage of the developer, a configuration using a side seal filled in a gap between the developer carrying member and the latent image carrying member opposed to the developer carrying member has been proposed (for example, Patent Document 1).
The side seal disclosed in Patent Document 1 is a buffer member that prevents the developer carrier and the photosensitive drum used in the latent image carrier from colliding with each other.
For this reason, the side seal is made of polyurethane rubber or the like having a thickness capable of coming into contact with both surfaces, and is attached to the casing of the developing device to prevent the collision between the two.

On the other hand, a developer scatter prevention seal is integrated with a part of the surface of the side seal.
The developer scattering prevention seal is a member used to prevent the developer from scattering from the end in the longitudinal direction of the developer carrier corresponding to a position where the magnetic constraint is weak.
For this reason, the developer scattering prevention seal is a sheet having a fiber bundle capable of closing the gap between the end of the developer carrying member and the end of the photosensitive drum facing the developer carrying member in the casing of the developing device. Is used.

The developer scattering prevention seal may be provided in the unit depending on the type of unit used in the developing device as well as the gap between the developer carrying member and the photosensitive drum.
For example, in the case where the units used in the developing device are formed by assembling the divided casings, a gateway agent scattering prevention seal is used at a part of the joint portion between the casings.

FIG. 8 shows a structure in the case where the divided casings are assembled together to form a unit.
The unit A shown in FIG. 8 is formed by the casings A1 and A2 divided in the vertical direction abutting the joint surfaces.
The upper casing A1 is provided with a developing sleeve B used as a developer carrying member, and the lower casing A2 is provided with a plurality of developer stirring members C and D and a layer thickness regulating member E used as developer conveying members. Is provided.

In the unit A, a housing as a developing device is formed by mounting the upper casing A1 on the lower casing A2.
The upper casing A1 is horizontally provided by a fitting portion (indicated by the symbol A3 for convenience) formed on the upper surface side of the lower casing A2 and an abutting portion (indicated by the symbol A4 for convenience) that abuts in the horizontal direction in the figure. They are integrated with each other so as not to be displaced in the direction.

  A side seal E for preventing the developer moving on the developing sleeve B rotating counterclockwise in the figure from leaking is formed on a part of the joining surface of the upper casing A1 and the lower casing A2. It is arrange | positioned in the upstream of the layer thickness control member F in the rotation direction.

The side seal E is made of a foamable resin that can be contracted and deformed, and is arranged at the end in the longitudinal direction where the magnetic restraining force is weak in the longitudinal direction of the developing sleeve B.
The side seal E fills the gap between the joining surfaces, whereby a part of the developer removed by the layer thickness regulating member F is pushed and moved to the longitudinal end of the developing sleeve B, and the joining portion between the casings From leaking outside.
In FIG. 8, reference numeral G denotes a developer scattering prevention seal that can close the gap between the developing sleeve B and the photosensitive drum (not shown).

In the developing device shown in FIG. 8, the side seal E covers the gap between the developing sleeve B and the layer thickness regulating member F in order to prevent the developer from leaking outside from the joint surface. When mounted on the casing A2, a part of the upper casing A1 may bite.
The reason why a part of the upper casing A1 bites into the side seal E is to ensure adhesion with the side seal E and to seal the region where the developer moves to prevent leakage to the outside.

When a part of the upper casing A1 bites into the side seal E, the part is depressed and deformed, and the other part is pulled toward the deformed part along with the depression.
For this reason, the pulled part leaves | separates from the surface of the casing which was contacting so far, and a clearance gap arises. As a result, the probability of the developer leaking from the gap increases, and the developer scatters to the periphery of the unit, causing contamination to peripheral devices and inadvertent adhesion to the recording medium.

  An object of the present invention is to provide a developing device, a process cartridge, and an image forming device that can reliably prevent a developer from leaking from a joint portion between casings when divided casings are assembled to form a unit. To provide an apparatus.

In order to achieve this object, the present invention has an upper and lower split type casing that forms a developer tank containing a developer, and a developer carrier, a developer agitating member, and the developer carrier within the developer tank. A developing device in which a layer thickness regulating member that regulates the layer thickness of the developer to be carried is disposed adjacent to the developing device,
A side seal for preventing leakage of the developer from the inside of the developing tank is provided at a position where the upper and lower divided casings are in contact with each other at the longitudinal end of the developer carrier,
A sheet-like sealing member made of a flexible resin is disposed between the side seal and one surface of the casing on the upstream side of the layer thickness regulating member in the moving direction of the developer on the developer carrier. And
The sheet-like seal member has a proximal end positioned at least between the side seal and the one side surface of the casing facing the side seal, and is integrated with the surface of the casing, and a distal end extends along the surface of the developer carrier. The developing device is extended in a fluttering state.

According to the present invention, even when the side seal is deformed and a gap is generated between the side seal and the casing, the developer moving space remains shielded by the presence of the sheet-like seal member.
As a result, the developer pushed toward the end in the longitudinal direction of the developer carrier is blocked by the sheet-like seal member, thereby preventing leakage to the outside.

It is a figure for demonstrating an example of the image formation to which the developing device which concerns on embodiment of this invention is applied. 1 is an external view of a process cartridge to which a developing device according to an embodiment of the present invention is applied. 1 is an external view of a developing device according to an embodiment of the present invention. FIG. 4 is a cross-sectional view for explaining the internal structure of the developing device shown in FIG. 3. FIGS. 4A and 4B are diagrams for explaining a configuration of a main part of a lower casing used in the developing device shown in FIG. 3. FIG. 4A shows a configuration according to the present embodiment, and FIG. . It is a schematic diagram for demonstrating the principal part structure in the image development apparatus which concerns on embodiment of this invention. It is a perspective view for demonstrating the modification of the principal part structure shown in FIG. It is a schematic diagram for demonstrating the conventional developer scattering prevention structure.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to embodiments shown in the drawings.
FIG. 1 is a diagram showing an image forming apparatus using a developing device according to an embodiment of the present invention. The image forming apparatus shown in FIG. 1 is a color laser printer 100 that uses a plurality of image forming units in a tandem system.

  In FIG. 1, a color laser printer 100 has an image forming unit 1A positioned at the center in the vertical direction, a sheet feeding unit 1B below the image forming unit 1A, and a document table 1C1 above the image forming unit 1A. A document scanning unit 1C is arranged.

  In the image forming unit 1A, a transfer unit composed of an intermediate transfer belt 2 is disposed as an intermediate transfer member having a horizontally extending surface, and the intermediate transfer belt 2 has a complementary color relationship with a color separation color. A configuration for forming an image of a certain color is provided.

The image forming unit 1A is provided with an image forming unit capable of forming an image with toners of complementary colors (yellow, magenta, cyan, black), and each image forming unit is a photosensitive member capable of carrying an image. The bodies 3B, 3C, 3M, and 3Y are juxtaposed along the stretched surface of the intermediate transfer belt 2.
In the following description, in the case of contents common to all the photoconductors, the photoconductor is denoted by reference numeral 3.

Each of the photoconductors 3B, 3C, 3M, and 3Y is used as a latent image carrier and is configured by a drum that can rotate in the same direction (counterclockwise in FIG. 1) (hereinafter, the photoconductor or photoconductor). May use both drums).
Around the photosensitive drum, there are arranged a charging device 4, a writing device 5, a developing device 6, a primary transfer device 7 which is one of transfer bias applying means, and a cleaning device 8 which execute image forming processing in the rotation process. Has been.
In FIG. 1, for convenience, the reference numerals of the respective devices are indicated by B with respect to the photoreceptor 3 </ b> B.

  The intermediate transfer belt 2 corresponds to a primary transfer unit to which a visible image from an image forming unit including each photoconductor is sequentially transferred. The intermediate transfer belt 2 is wound around a plurality of rollers 2A to 2C and is connected to the photoconductor. It can move in the same direction at the opposite position.

  In the intermediate transfer belt 2, a roller 2 </ b> C disposed at a position other than the developing surface facing the image forming unit is opposed to the secondary transfer device 9.

The secondary transfer device 9 includes a transfer belt 9C that is wound around the charging drive roller 9A and the driven roller 9B and is movable in the same direction as the intermediate transfer belt 2 at the secondary transfer position where the secondary transfer device 9 is located. Yes.
By charging the transfer belt 9C with the charging drive roller 9A, the multi-color image superimposed on the intermediate transfer belt 2 in the process of transporting the recording sheet while electrostatically attracting it is transferred by batch transfer or a single color image carried thereon. Each can be transferred to a recording sheet.

A recording sheet is fed from the paper feeding unit 1B to the secondary transfer position.
The paper feed unit 1B includes a plurality of paper feed cassettes 1B1, a plurality of transport rollers 1B2 arranged in a transport path for recording sheets fed from the paper feed cassette 1B1, and a registration roller 1B3 positioned in front of the secondary transfer position. I have.

In the configuration shown in FIG. 1, in the sheet feeding unit 1B, in addition to the conveyance path of the recording sheet fed out from the sheet feeding cassette 1B1, a type of recording sheet not stored in the sheet feeding cassette 1B1 is directed to the secondary transfer position. A structure capable of feeding is provided.
This structure includes a manual feed tray 1A1 and a feeding roller 1A2 provided so that a part of the wall surface of the image forming unit 1A can be turned upside down.

In the middle of the recording sheet conveyance path from the sheet feeding cassette 1B1 to the registration roller 1B3, the conveyance path for the recording sheet fed from the manual feed tray 1A1 is joined.
The registration timing is set by the registration roller 1B3 for the recording sheet fed from any conveyance path.

The writing device 5 (in FIG. 1, for convenience, writing light for forming a black image is indicated by reference numeral 5B), the photosensitive drums 3B, 3C, 3M, and 3Y emit writing light corresponding to image information. Outputs an electrostatic latent image.
As the image information in this case, image information obtained by scanning the document on the document table 1C1 in the document scanning unit 1C or image information output from a computer (not shown) is used.

The document scanning unit 1C is provided with a scanner 1C2 that exposes and scans the document on the document table 1C1, and an automatic document feeder 1C3 is disposed on the upper surface of the document table 1C1.
The automatic document feeder 1C3 has a configuration capable of reversing the document fed on the document table 1C1, and can perform scanning on both sides of the document.

  An electrostatic latent image on the photosensitive member 3 (members indicated by reference numerals 3B, 3C, 3M, and 3Y in FIG. 1) formed by the writing device 5 is indicated by reference numeral 6B in FIG. 1 for convenience. ) To process the visible image.

  The toner image subjected to the visible image processing is primarily transferred to the intermediate transfer belt 2. When the toner image for each color is superimposed and transferred onto the intermediate transfer belt 2, the secondary transfer device 9 performs secondary transfer on the recording sheet at once.

The unfixed image carried on the surface of the recording sheet that has been secondarily transferred is fixed by the fixing device 11.
Although not described in detail, the fixing device 11 uses a belt fixing structure that includes a fixing belt heated by a heating roller and a pressure roller that contacts and contacts the fixing belt.

  In the fixing device 11, by providing a contact area between the fixing belt and the pressure roller, that is, a nip area, a heating area for the recording sheet can be widened as compared with the fixing structure of the heat roller type.

  The recording sheet that has passed through the fixing device 11 is switched in the transport direction by a transport path switching claw 12 disposed behind the fixing device 11, and is transported toward the paper discharge tray 13 and reversely transported. A transport direction is selected for the path RP.

In the color laser printer 100 having the above-described configuration, the following image forming process is executed.
An electrostatic latent image is formed on the uniformly charged photoreceptor 3 by exposure scanning of the document placed on the document placement table 1C1 or by image information from the computer. After the visible image processing, the toner image is primarily transferred to the intermediate transfer belt 2.

In the case of a single color image, the toner image transferred to the intermediate transfer belt 2 is transferred as it is to the recording sheet fed out from the paper feed unit 1B.
In the case of a multi-color image, primary transfer is repeated and superimposed, and then secondary transfer is performed collectively on the recording sheet.
The recording sheet after the secondary transfer is fixed with an unfixed image by the fixing device 11 and then fed to the paper discharge tray 13 or reversed and fed again toward the registration roller 1B3.

In FIG. 1, reference numeral 10 denotes a cleaning device.
The cleaning device 10 is provided for the intermediate transfer belt 2 separately from each photoconductor.
The cleaning device 10 is disposed on the upstream side of the yellow image forming section which is the first image forming section in the moving direction of the intermediate transfer belt 2.
Although not shown in detail, the cleaning device 10 includes a cleaning blade, a cleaning brush, and a waste toner collecting mechanism.

Each image forming unit uses a process cartridge 101 shown in FIG.
The process cartridge 101 contains the following members among the members described in FIG.
A charging device (not shown) for performing image forming processing on the photosensitive drum, a developing unit (denoted by reference numeral 6 for convenience) used as a developing device, and a cleaning unit (denoted by reference numeral 8 for convenience) used for the cleaning apparatus. Contained together.
The writing device 5 and the intermediate transfer belt 2 are provided separately from the process cartridge, as shown in FIG.

FIG. 3 is an external view of a developing unit 6 (hereinafter also referred to as developing unit 6) used in the developing device provided in the process cartridge 101 shown in FIG.
The developing unit 6 includes an upper casing 61 having an opening through which a developing sleeve 60 used as a developer carrying member can expose a part of its peripheral surface to the outside, and a lower casing 62 on which a joint surface of the upper casing is mounted. It is a unit that combines.
The developing unit 6 is a unit that forms a developing tank in which a developer is accommodated by combining upper and lower casings with the end portions in the longitudinal direction being brought into contact with each other.

FIG. 4 is a cross-sectional view showing the internal structure of the developing unit 6.
In the developing unit 6 that is inside the developing tank, a developing sleeve 60 that is a developer carrying member is disposed on the upper casing 61 side, and a pair of conveying screws 63 that are developer agitating members that agitate the developer in the conveying process, 64 and the layer thickness regulating member 65 are arranged on the lower casing 62 side.

The developing sleeve 60 can be rotated counterclockwise in FIG. 4, and the developer can be raised on the surface by a plurality of magnetic poles which are built-in magnetic force generating means.
The spiked developer rolls on the surface of the developing sleeve 60 by the magnetic restraining force of the magnetic force generating means and the rotational force of the developing sleeve 60.

Of the conveying screws 63, 64, the conveying screw 63 disposed in the space facing the developing sleeve 60 is used as a supply-side screw that pumps up the developer and supplies it to the developing sleeve 60.
The conveying screw 64 disposed in the space where the surface moves after facing the photosensitive drum 3 (see FIG. 1) in the rotation direction of the developing sleeve 60 utilizes the repulsion of magnetic force due to the magnetic pole arrangement in the developing sleeve 60. It is used as a recovery side screw for the developer recovered in this way.

The supply-side transport screw 63 and the recovery-side transport screw 64 have their screw lead directions determined so that the developer moving directions along the axial direction corresponding to the longitudinal direction are opposite to each other.
Both the conveying screws 63 and 64 move the developer in the axial direction while rotating, but the collecting-side conveying screw 64 includes toner to be newly replenished in accordance with a detection result of a toner concentration detection sensor (not shown). Then stir and mix the developer.

On the other hand, at the position where the developer is pumped up by the supply-side conveying screw 63, a layer thickness regulating member 65 having a leading end facing the developing sleeve 60 close thereto is disposed.
The layer thickness regulating member 65 is a blade member, and a leading end thereof is positioned with a predetermined gap with respect to the surface of the developing sleeve 60.

  In the developing unit 6 shown in FIG. 4, the upper and lower casings are assembled with the opposing surfaces of the upper and lower casings as the joint surfaces, as in the configuration shown in FIG.

The features of the developing device according to the present embodiment will be described below with the above configuration as a target.
A feature of the developing device according to this embodiment is that a sheet-like seal member is provided that blocks the developer from moving toward the downstream side of the layer thickness regulating member in the developer moving direction regardless of the deformation of the side seal. There is.

The development unit 6 uses a vertically divided casing that is divided into upper and lower parts, and a side seal 66 is disposed on the joint surface as in the case shown in FIG.
The side seal 66 is a shaft on the downstream side of the layer thickness regulating member 65 in the rotational direction corresponding to the moving direction of the developing sleeve 60, which is a position where the magnetic restraining force is weakened in the axial direction of the developing sleeve 60, that is, at both longitudinal ends. It is arrange | positioned at the direction both ends, respectively.

FIG. 5 is a view showing the lower casing 62 side corresponding to one side of the upper and lower split casing, and shows an axial end corresponding to the longitudinal direction of the developing sleeve 60 on the lower casing 62 side. ing.
In FIG. 5B, the side seal 66 is not shown, but is loaded in the vicinity of the layer thickness regulating member 65 on the upstream side in the developer moving direction (arrow direction in the figure) on the developing sleeve 60.

Between the side seal 66 and the surface of the lower casing 62 that is one surface of the casing facing the side seal 66, as shown in FIG. 6, a sheet-like seal member A67 is disposed.
For the sheet-like seal member 67, a flexible resin such as PET (polyethylene terephthalate) is used.

  The sheet-like seal member 67 is at least between the side seal 66 positioned on the upstream side of the layer thickness regulating member 65 in the rotation direction of the developing sleeve 60 and the surface of the lower casing 62 that is one casing facing the side seal 66. The proximal end 67A is positioned.

The base end 67A side of the sheet-like seal member 67 is not attached to the side seal 66 side but is attached to the lower casing 62 with a double-sided adhesive tape and integrated.
Thereby, the sheet-like seal member 67 can be maintained in a state of being fixed to the lower casing 62 regardless of the deformation of the side seal 66.

The base end 67A side of the sheet-like seal member 67 is not limited to just between the side seal 66 and the surface of the lower casing 62 facing the side seal 66, but can be extended so as to bypass the lower surface of the side seal 66. .
That is, since the lower surface of the side seal 66 is opposed to the joint surfaces of the upper and lower casings 61 and 62, the base end can be positioned at a position sandwiched between the joint surfaces.
FIG. 5A shows a state in which the base end of the sheet-like seal member 67 (indicated by reference numeral 67A ′ for the sake of convenience) is extended toward the lower surface of the side seal 66 and part of the sheet seal member 67 protrudes from the lower surface of the side seal 66. ing. In FIG. 5, the arrow indicates the moving direction of the developer.

On the other hand, the front end 67B of the sheet-like seal member 67 extends upward from the base end located on the lower casing 62 side, and extends along the surface of the developer carrier, that is, the surface of the developing sleeve 60 as shown in FIG. It is extended by touching and fluttering.
In addition, the leading end side of the sheet-like seal member 67 is positioned downstream of the position of the layer thickness regulating member 65 in the rotation direction of the developing sleeve 60.
Since the sheet-like seal member 67 has a curved shape in the middle from the base end side to the tip, the tip can be easily pressed against the surface of the developing sleeve 60 by a shape restoring force using its own bending rigidity.

The front end side of the sheet-like seal member 67 is sandwiched between developer scattering prevention seals 68 that shield the facing gap between the developing sleeve 60 and the photosensitive drum 3.
Thereby, the front end side of the sheet-like seal member 67 is pressed against the surface of the developing sleeve 60 using not only its own shape restoring force but also the pressure of the developer scattering prevention seal 68.
In FIG. 6, the shape of the developer scattering prevention seal 68 other than the end portion in the axial direction of the developing sleeve 60 is indicated by a two-dot chain line.
However, at the end of the developing sleeve 60 in the axial direction, the sheet-like seal member 67 can be pressed against the surface of the developing sleeve 60 for the purpose of shielding the side end so as to prevent leakage from the end to the outside. It is shrinking and deformed.

The sheet-like seal member 67 is disposed at a position where the magnetic restraining force is weakened at both ends in the longitudinal direction of the developing sleeve 60 where the magnetic plate 65A attached to the layer thickness regulating member 65 is located, that is, at both ends in the axial direction. ing.
Thereby, even if the developer excluded by the layer thickness regulating member 65 tries to move with the rotation of the developing sleeve 60 at the position where the magnetic restraining force is weakened, the moving space is shielded by the sheet-like seal member 67. Is prevented from moving.
As a result, the developer excluded by the layer thickness regulating member 65 does not pass through the gap between the developing sleeve 60 and the layer thickness regulating member 65 and move toward the downstream side in the developer moving direction. This portion does not leak to the outside (the state indicated by the two-dot chain line arrow in FIG. 6).

In particular, even when a part of the lower casing 62 is abutted against the side seal 66 and a part of the side seal 66 is compressed and deformed, the leading end 67B of the sheet-like seal member 67 is irrespective of the deformation of the side seal 66. It remains pressed against the surface.
As a result, the tip 67B side does not move away from the developing sleeve 60, and thus the state in which the developer excluded by the layer thickness regulating member 65 is shielded from the space to move downstream of the layer thickness regulating member 65 is maintained. Can do.

In the above configuration, a structure that can prevent the leakage of the developer can be obtained by simply bending the flat sheet-like seal member 67 between the side seal 66 and the surface of the lower casing facing the side seal 66. It is not necessary to use a simple leakage prevention structure.
In addition, the habit of pressing the tip 67B against the surface of the developing sleeve 60 requires only the use of the shape restoring force generated during bending and the developer scattering prevention seal 68, which is an existing structural component. It is possible to reliably prevent the ejection.

Next, a modified example of the sheet-like seal member will be described.
In FIG. 7, unlike the case shown in FIG. 6, the sheet-like seal member 67 is formed of a foamable resin such as polyurethane rubber.
Since such a material is the same as that of the side seal 66, the side seal 66 can be formed by a part of the sheet-like seal member 67. In other words, the sheet-like seal member 67 can also be used as the side seal 66.
FIG. 7 shows a state in which the side seal 66 is combined with a part of the sheet-like seal member 67.

  In the above configuration, the sheet-like seal member 67 and the side seal 66 do not need to be separated, and can be prepared in advance as an integral member, so that the processing cost can be reduced.

6 Developing Unit 60 Developing Sleeve 61 Upper Casing 62 Lower Casing 63, 64 Stirring Screw 65 Layer Thickness Restricting Member 66 Side Seal 67 Sheet-like Sealing Member 67A, 67A ′ Base End 67B Tip 68 Developer Scattering Prevention Seal 100 Image Forming Apparatus 101 Process cartridge

JP 2009-58994 A

Claims (7)

The developer tank has a vertically divided casing that forms a developer tank for containing the developer. Inside the developer tank, a developer carrier, a developer agitating member, and a developer carrier carried in the vicinity of the developer carrier. A developing device in which a layer thickness regulating member for regulating the layer thickness is disposed,
A side seal for preventing leakage of the developer from the inside of the developing tank is provided at a position where the upper and lower divided casings are in contact with each other at the longitudinal end of the developer carrier,
A sheet-like sealing member made of a flexible resin is disposed between the side seal and one surface of the casing on the upstream side of the layer thickness regulating member in the moving direction of the developer on the developer carrier. And
The sheet-like seal member has a proximal end positioned at least between the side seal and the one side surface of the casing facing the side seal, and is integrated with the surface of the casing, and a distal end extends along the surface of the developer carrier. A developing device that is extended in a fluttering state.   One side of the casing in which the sheet-like seal member is integrated is a lower casing, and the tip of the sheet-like seal member faces upward from a base end located on the lower casing side. The developing device according to claim 1, wherein the developing device is in contact with the developing device.   The front end of the sheet-like seal member is in contact with the surface of the developer carrier on the downstream side of the layer thickness regulating member in the moving direction of the developer carrier. Development device.   2. The sheet-like seal member is disposed in a region where a magnetic force from a magnetic field generating means built in the developer carrier is weak at least at both longitudinal ends of the developer carrier. 4. The developing device according to any one of 3.   A seal member for preventing scattering of the developer is disposed in a facing gap between the developer carrier and the latent image carrier, and the seal member has a leading end of the sheet-like seal member and the surface of the developer carrier. The developing device according to claim 1, wherein the developing device is sandwiched between the developing devices.   A process cartridge comprising the developing device according to claim 1.   An image forming apparatus using the process cartridge according to claim 5.

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