JP6115154B2 - Development device - Google Patents

Description

  The present invention relates to a developing device including a developing roller.

  In general, an image forming apparatus is provided with a developing device including a developing roller rotatably provided in a housing, a photosensitive drum, a transfer roller, and the like, and a developer image is formed on the photosensitive drum during image formation. The developer image is transferred to a recording sheet or the like. In the photosensitive drum of such an image forming apparatus, developer or the like that could not be transferred onto the recording sheet or the like remains on the surface, and therefore it is necessary to appropriately reset the surface by cleaning them.

  Patent Document 1 discloses a so-called cleanerless type image forming apparatus in which a cleaning member for cleaning a photosensitive drum is not provided. In this image forming apparatus, the surface of the photosensitive drum is cleaned by collecting deposits such as developer on the surface of the photosensitive drum with a developing roller.

  Such a developing roller is finished by polishing the surface with a grindstone at the time of manufacture. For example, in the developing roller disclosed in Patent Document 2, the frictional force on the surface of the developing roller is reduced by setting the polishing eye to be the order with respect to the rotation direction of the developing roller. Further, in the developing roller disclosed in Patent Document 3, the amount of developer transported is made constant by making the polishing eye reverse to the rotation direction of the developing roller.

JP 2005-292460 A JP-A-9-160373 JP-A-8-286501

  By the way, in the cleanerless type image forming apparatus, if the photosensitive drum surface is not properly reset by the developing roller without collecting the adhered matter on the surface of the photosensitive drum, foreign matter adheres to the surface of the photosensitive drum, so-called filming problems. Is likely to occur. For this reason, further improvement in the resetability of the photosensitive drum by the developing roller is required.

However, with the developing roller of Patent Document 2, since the frictional force on the surface of the developing roller is small, deposits on the surface of the photosensitive drum cannot be scraped off with the polishing eyes, and the resetability of the photosensitive drum cannot be further improved.
On the other hand, the developing roller disclosed in Patent Document 3 has a problem that the polishing force is reversed and the frictional force on the surface of the developing roller increases, resulting in poor sliding performance with a contact member such as a seal member.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device that can further improve the resetting property of a photosensitive drum by a developing roller and improve the sliding property of the developing roller.

In order to achieve the above-described object, a developing device of the present invention includes a housing configured to store a developer, and a developing roller rotatably provided in the housing.
As for the polishing marks on the surface of the developing roller, the end of the developing roller in the axial direction is not at least opposite to the rotation direction of the developing roller, and the central portion of the developing roller in the axial direction is opposite to the rotation direction. It is.

  According to such a configuration, since the polishing eye at the center of the developing roller is reverse to the rotation direction, the polishing eye at the center can be brought into sliding contact with the photosensitive drum. For this reason, the deposits on the photosensitive drum can be scraped off by the polishing marks of the developing roller, and the resetting property of the photosensitive drum can be improved.

  Further, since the polishing marks at the end of the developing roller are not at least opposite to the rotation direction, the surface frictional force at the end of the developing roller can be reduced as compared with the center. Therefore, as compared with the configuration in which the polishing roller of the entire developing roller is reverse to the rotation direction, the sliding property between the developing roller and the portion of the housing where the developing roller contacts (seal member, etc.) is improved. Can do.

  The term “polishing eye” as used herein refers to a minute protrusion formed by polishing the surface of the developing roller. Further, the forward order refers to the case where the polishing eye is inclined in the direction opposite to the rotation direction of the developing roller, and the reverse eye refers to the case where the polishing eye is inclined in the rotation direction of the developing roller.

  In the configuration described above, the developing device contacts the developing roller at the end of the developing roller between the housing and the developing roller, and regulates the layer thickness of the developer on the developing roller. When the plate-shaped layer thickness regulating blade is configured to be configured, the portion of the layer thickness regulating blade that contacts the developing roller is outside the inner end of the seal member in the axial direction in the axial direction. It can be set as the structure extended to. Further, in the layer thickness regulating blade in this configuration, a portion that contacts the developing roller may be formed of metal.

  According to such a configuration, the contact pressure of the layer thickness regulating blade at the end portion of the developing roller is increased, but since the polishing marks of the developing roller are not reverse at the end portion, the developing roller and the layer thickness regulating blade Slidability can be ensured, and the developing roller is less likely to be scraped.

  In the above-described configuration, the polishing marks on the surface of the developing roller can be configured such that the end of the developing roller is in order with respect to the rotation direction.

  According to such a configuration, the abrasive eyes slide in contact with the casing (seal member) so that the frictional force on the surface of the end portion of the developing roller can be further reduced. Therefore, the slidability at the end of the developing roller can be improved.

  In the above-described configuration, the inner end portion of the seal member in the axial direction may be positioned outside the boundary between the end portion and the central portion of the developing roller.

  According to such a configuration, since only the end portion of the developing roller whose polishing eyes are not reversed slides with the seal member, the slidability between the developing roller and the seal member can be further improved.

  In the configuration described above, when the developing device includes a supply roller configured to supply the developer to the developing roller, the axial end portion of the supply roller is a boundary between the end portion of the developing roller and the central portion. It can be set as the structure located inside.

  According to such a configuration, since the polishing marks of the developing roller are reliably located in the range where the supply roller is located, the developer can be reliably carried on the surface of the developing roller in that range. Therefore, the presence or absence of polishing eyes can be freely set at the end of the developing roller, and the degree of freedom in the manufacturing process of the developing roller can be increased.

  In the above-described configuration, when the developing device includes a supply roller configured to supply the developer to the developing roller, the polishing marks on the surface of the developing roller have an end portion of the developing roller with respect to the rotation direction. In this order, the end of the supply roller in the axial direction may be positioned outside the boundary between the end and the center of the developing roller.

  According to such a configuration, since the end of the developing roller has polishing eyes, even if the supply roller is disposed at the position of the end of the developing roller, the developer can be sufficiently carried at that position. Printing capability is maintained. Therefore, the developing roller can be shortened in the axial direction, and the entire developing device can be reduced in size.

  According to the present invention, the resetting property of the photosensitive drum by the developing roller can be improved, and the sliding property of the developing roller can be improved.

1 is a cross-sectional view of a laser printer including a developing cartridge according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a developing cartridge according to an embodiment of the present invention. FIG. 5 is a diagram of a state in which the developing roller of the developing cartridge is disassembled as viewed from the back. FIG. 3 is an enlarged view of the developing roller in FIG. 2. FIG. 6 is a cross-sectional view of the periphery of the developing roller and side seal member on the right side of the developing cartridge. It is a figure equivalent to FIG. 3 which concerns on a 1st modification.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, the overall configuration of a laser printer according to an embodiment of the present invention will be described, and then the features of the present invention will be described in detail.

  In the following description, the direction will be described with reference to the user when using the laser printer. That is, in FIG. 1, the left side toward the paper surface is “front side”, the right side toward the paper surface is “rear side”, the rear side toward the paper surface is “left side”, and the front side toward the paper surface is “right side”. To do. In addition, the vertical direction toward the page is defined as the “vertical direction”.

<Schematic configuration of laser printer>
As shown in FIG. 1, the laser printer 1 includes an apparatus main body 2, a feeder unit 3 for feeding paper P, a scanner unit 4, a process cartridge 5 for transferring a toner image onto the paper P, and a paper And a fixing device 7 for thermally fixing the toner image on P.

  The apparatus main body 2 includes a top cover 22 and a front cover 23. Further, the apparatus main body 2 has an opening 21A for attaching / detaching a process cartridge 5 (described later) at the upper part thereof, and an insertion port 21B for inserting the paper P at the front part thereof.

  The front cover 23 is provided with a rotating shaft 23A of the front cover 23 at a lower portion on the front side of the apparatus main body 2, and rotates forward about the rotating shaft 23A. In FIG. 1, the front cover 23 indicated by a two-dot chain line is in a state where the front side of the apparatus main body 2 is closed, and the front cover 23 indicated by a solid line is in a state where the front side of the apparatus main body 2 is opened.

The feeder unit 3 is located below the apparatus main body 2 and includes a paper feed tray 31 on which the paper P is placed and a paper feed mechanism 32 that feeds the paper P on the paper feed tray 31.
The paper feed tray 31 includes a mounting table 31 </ b> A disposed at the lower part of the apparatus main body 2 and the above-described front cover 23.

  The paper feed mechanism 32 mainly includes a paper feed roller 32A, a separation roller 32B, and a separation pad 32C. The paper feed roller 32A is arranged on the upstream side of the separation roller 32B in the transport direction of the paper P and on the rear end of the placement table 31A. The separation roller 32B is disposed to face the separation pad 32C.

  In the feeder unit 3, after the front cover 23 is tilted forward to form the paper feed tray 31, the paper P is placed on the paper feed tray 31. Then, when the paper feed roller 32A comes into contact with the paper P placed on the paper feed tray 31 and rotates, the paper P placed on the paper feed tray 31 is sent to the separation roller 32B and sent out. The sheets P are separated one by one between the separation roller 32 </ b> B and the separation pad 32 </ b> C and conveyed toward the process cartridge 5.

  The scanner unit 4 is provided on the front side in the apparatus main body 2 and includes a laser light emitting unit, a polygon mirror, a lens, a reflecting mirror, and the like (not shown). In this scanner unit 4, a laser beam is irradiated on the surface of a photosensitive drum 61 described later by high-speed scanning.

  The process cartridge 5 is located near the center of the rear side of the apparatus main body 2 and is provided above the paper feed mechanism 32. The process cartridge 5 is configured to be attachable to and detachable from the apparatus main body 2 through the opening 21A and includes a drum unit 6 and a developing cartridge 10 as an example of a developing device.

As shown in FIG. 2, the drum unit 6 includes a drum frame 69, a photosensitive drum 61 provided on the drum frame 69, a charger 62, and a transfer roller 63.
The developing cartridge 10 includes a casing 100, a developing roller 110, a supply roller 120, and a layer thickness regulating blade 130, and is detachable from the drum unit 6. Details of the casing 100 and the layer thickness regulating blade 130 will be described later.

The developing roller 110 is a member configured to carry toner on the peripheral surface, and is provided in the housing 100 to be rotatable. Details of the developing roller 110 will be described later.
The supply roller 120 is a member configured to supply toner attached to the peripheral surface thereof to a central portion 112 (see FIG. 3) of the developing roller 110, which will be described later, and is disposed obliquely below the developing roller 110. ing. The supply roller 120 is made of a sponge material (foamed resin) such as urethane foam.

  In the developing cartridge 10, the toner stored in the toner storage chamber 101 formed in the housing 100 is stirred by the agitator 102 and then supplied to the developing roller 110 by the supply roller 120. At this time, the toner is positively frictionally charged between the supply roller 120 and the developing roller 110. The toner supplied onto the developing roller 110 enters between the layer thickness regulating blade 130 and the developing roller 110 as the developing roller 110 rotates, and is further developed as a thin layer having a constant thickness while being frictionally charged. It is carried on a roller 110.

  In the drum unit 6, the surface of the rotating photosensitive drum 61 is uniformly charged by the charger 62 and then exposed by high-speed scanning of the laser beam from the scanner unit 4. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image based on the image data is formed on the surface of the photosensitive drum 61.

  Next, toner from the developing cartridge 10 is supplied to the electrostatic latent image, and a toner image is formed on the surface of the photosensitive drum 61. Thereafter, the paper P is conveyed between the photosensitive drum 61 and the transfer roller 63, whereby the toner image carried on the surface of the photosensitive drum 61 is transferred onto the paper P.

  Returning to FIG. 1, the fixing device 7 is located at the upper rear of the apparatus main body 2 and is disposed above the process cartridge 5. The fixing device 7 mainly includes a heating roller 71 and a pressure roller 72.

The heating roller 71 is a member that heats the paper P, and a heat source (not shown) such as a halogen lamp is provided therein.
The pressure roller 72 is a member that sandwiches and conveys the paper P with the heating roller 71 and is provided obliquely above the heating roller 71.

  In the fixing device 7 configured as described above, the toner transferred onto the paper P is thermally fixed while the paper P passes between the heating roller 71 and the pressure roller 72. The paper P thermally fixed by the fixing device 7 is conveyed to a discharge roller 8 disposed on the downstream side of the fixing device 7, and is discharged from the discharge roller 8 onto a discharge tray 9.

<Detailed configuration of developing cartridge>
Next, the configuration of the developing cartridge 10 will be described. Since the developing cartridge 10 has a symmetrical configuration, only one of the left and right parts is shown in FIG. 3, and the other part is omitted.

  As shown in FIG. 3, the housing 100 has an opening 103 formed in the rear side wall, and the developing roller 110 and the layer thickness regulating blade 130 are attached so as to close the opening 103. The opening 103 is provided with a side seal member 140, an upper seal member 150, a film 160, and the like as examples of a seal member in order to prevent the toner in the housing 100 from leaking. A layer thickness regulating blade 130 is disposed at the upper edge of the opening 103. Both end portions of the layer thickness regulating blade 130 are fixed to the upper edge of the opening 103 with screws or the like.

  The layer thickness regulating blade 130 supports the blade body 131 formed of a metal plate, the blade body 131 that supports the blade body 131, and the blade body 132 between the blade holder 132 and the blade holder 132. It is comprised from the reinforcement board 133. FIG. The layer thickness regulating blade 130 regulates the toner layer thickness on the developing roller 110 when the tip 131A of the blade body 131 comes into contact with the developing roller 110. The tip 131A of the blade body 131 extends to the outside of the inner end 141 in the left-right direction of the side seal member 140 in the left-right direction.

  The side seal member 140 is disposed between the casing 100 and the developing roller 110 at the end 111 of the developing roller 110, and includes a sliding contact member 140 A that contacts the end 111 of the developing roller 110, and the casing 100. It has the base material 140B arrange | positioned between the sliding contact members 140A.

The upper seal member 150 is disposed between the casing 100 and the layer thickness regulating blade 130 and is in contact with the upper end of the side seal member 140 (see FIG. 5).
The film 160 is fixed to the casing 100 along the lower edge of the opening 103 between the developing roller 110 and the casing 100, and the tip portion can be slidably contacted with the peripheral surface of the developing roller 110. .

<Detailed configuration of developing roller>
Next, details of the developing roller 110 will be described.
The developing roller 110 has a surface made of rubber, and includes an end portion 111 positioned at both end portions in the left-right direction and a center portion 112 positioned at the center portion in the left-right direction.

  As shown in FIG. 4, the central portion 112 of the developing roller 110 has a polishing eye 112 </ b> A that is reverse to the rotation direction of the developing roller 110 on the surface by polishing. In FIG. 4, for the sake of convenience, the polishing eyes 112A are exaggerated. On the other hand, the end 111 of the developing roller 110 in this embodiment does not have a polishing eye. Here, the absence of polishing eyes includes both cases where polishing is not performed, or polishing is performed with very fine eyes, and the polishing eyes are substantially absent by finishing.

  As shown in FIG. 3, the boundary 113 between the end portion 111 and the central portion 112 of the developing roller 110 is located on the inner side in the left-right direction with respect to the inner end portion 141 of the side seal member 140. In other words, the inner end 141 of the side seal member 140 is located on the outer side in the left-right direction with respect to the boundary 113. As a result, only the end 111 of the developing roller 110 slides with the side seal member 140.

  Further, the boundary 113 between the end portion 111 and the central portion 112 of the developing roller 110 is located on the outer side in the left-right direction with respect to the end portion 120 </ b> A in the left-right direction of the supply roller 120. In other words, the end 120 </ b> A in the left-right direction of the supply roller 120 is located on the inner side in the left-right direction than the boundary 113. As a result, the polishing marks 112A of the central portion 112 of the developing roller 110 are surely located in the range where the supply roller 120 is located.

  Further, when in use, the developing roller 110 rotates in the opposite direction to the photosensitive drum 61 (the same direction as the direction of movement of the photosensitive drum 61 at the contact portion) so that the peripheral speed is higher than the peripheral speed of the photosensitive drum 61. Set to

[Polishing method]
As a polishing method, for example, the grindstone and the developing roller 110 are brought into contact with each other, and the grindstone and the developing roller 110 are respectively rotated in opposite directions (the respective traveling directions in the contact portion are the same direction), whereby the entire surface of the developing roller 110 is made. Grind. Regarding the peripheral speed, the peripheral speed of the grindstone is set to be larger than the peripheral speed of the developing roller 110. By doing in this way, the surface of the developing roller 110 is torn off by the grindstone, and polishing marks are formed. At this time, the developing roller 110 is disposed on the entire surface of the developing roller 110 such that a polishing eye that is opposite to the rotation direction when the developing roller 110 is used is formed. The polishing marks are preferably formed so that the height is in the range of 6 to 10 μm.

  Next, after performing the above-described polishing process or the like, the end 111 of the developing roller 110 is polished with a fine grindstone so that the end of the end 111 is removed. In this way, the developing roller 110 according to the present embodiment can be easily manufactured. The polishing method is not limited to this, and can be appropriately changed as long as desired polishing eyes can be obtained.

  In the developing cartridge 10 configured as described above, the developing roller 110 rotates while the central portion 112 is in contact with the surface of the photosensitive drum 61. At this time, the developing roller 110 rotates in the opposite direction to the photosensitive drum 61, and the peripheral speed is higher than the peripheral speed of the photosensitive drum 61. Here, if the polishing marks on the surface of the developing roller 110 are in order with respect to the rotation direction of the developing roller 110, the polishing marks slide along the photosensitive drum 61 so that the photosensitive drum 61 is sufficiently attached. Kimono cannot be scraped off. However, in this embodiment, the polishing marks 112A of the central portion 112 of the developing roller 110 are opposite to the rotation direction, and the peripheral speed of the developing roller 110 is higher than the peripheral speed of the photosensitive drum 61. The 112 polishing eyes 112 </ b> A are inclined in the opposite direction to the relative movement direction of the photosensitive drum 61 at the contact portion with the photosensitive drum 61. Therefore, since the polishing marks 112A of the central portion 112 can be brought into sliding contact with the photosensitive drum 61, the deposits on the photosensitive drum 61 can be scraped off by the polishing marks 112A of the developing roller 110. Can be improved.

  On the other hand, if the polishing eye of the entire developing roller 110 is reverse to the rotation direction, the polishing eye is in sliding contact with the housing 100 (side seal member 140) so that the surface at the end 111 of the developing roller 110 Frictional force increases, and the sliding property between the developing roller 110 and the housing 100 deteriorates. However, in this embodiment, since the end 111 of the developing roller 110 does not have a polishing eye (at least not reverse), the frictional force of the surface at the end 111 of the developing roller 110 compared to the central portion 112. Can be reduced. Therefore, the sliding property between the developing roller 110 and the side seal member 140 on the housing 100 can be improved as compared with a configuration in which the polishing eye of the entire developing roller 110 is reverse to the rotation direction.

  In addition, since the side seal member 140 is in sliding contact with only the end portion 111 of the developing roller 110 having no polishing marks, the slidability between the developing roller 110 and the side seal member 140 can be further improved.

  In addition, since the polishing marks 112A of the developing roller 110 are reliably positioned in the range where the supply roller 120 is positioned, the toner can be reliably carried on the surface of the developing roller 110 in that range. Therefore, the presence or absence of polishing eyes can be freely set at the end 111 of the developing roller 110, and the degree of freedom in the manufacturing process of the developing roller 110 can be increased.

  In the present embodiment, the tip 131A of the layer thickness regulating blade 130 extends to the outside of the inner end 141 of the side seal member 140 in the left-right direction, so that the layer thickness is regulated near the end 111 of the developing roller 110. The contact pressure of the blade 130 is increased. Therefore, when no countermeasure is taken, it becomes impossible to ensure the sliding property between the developing roller 110 and the side seal member 140 at the end 111 of the developing roller 110 where the toner functioning as a lubricant does not flow. there is a possibility. However, in this embodiment, since the end 111 of the developing roller 110 does not have polishing eyes (the polishing eyes are not reverse), the slidability between the developing roller 110 and the layer thickness regulating blade 130 can be ensured, and development is performed. The roller 110 is less likely to be scraped off.

  Further, if the polishing marks 112A remain to such an extent that the deposits on the surface of the photosensitive drum 61 can be scraped off, the slidability of the developing roller 110 can be further improved by coating the surface of the developing roller 110 with polyurethane, fluorine, or the like. it can. Further, the slidability of the developing roller 110 can be further improved by curing the surface of the end 111 of the developing roller 110 by ultraviolet irradiation or the like.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention. In the following description, components that are substantially the same as those in the above embodiment are given the same reference numerals and description thereof is omitted.

<First Modification>
In the above-described embodiment, the end 111 of the developing roller 110 does not have a polishing eye, but the present invention is not limited to this, and may have a polishing eye as shown in FIG.
The developing roller 210 in this configuration is composed of an end portion 211 and a central portion 212 as in the above embodiment (see FIG. 6).

  Further, the end 211 of the developing roller 210 has a polishing eye 211A that becomes the order in the rotation direction of the developing roller 210 on the surface. In FIG. 5, the polishing eye 211A is exaggerated for convenience.

  A boundary 213 between the end portion 211 and the central portion 212 of the developing roller 210 is located on the inner side in the left-right direction with respect to the end portion 120A in the left-right direction of the supply roller 120, as shown in FIG. In other words, the end 120 </ b> A in the left-right direction of the supply roller 120 is located on the outer side in the left-right direction with respect to the boundary 213. That is, a part of the end portion 211 of the developing roller 210 is also located in the range where the supply roller 120 is disposed.

[Polishing method]
As a polishing method, the surface of the developing roller 210 is polished by bringing the grindstone and the developing roller 210 into contact with each other and rotating the grindstone and the developing roller 210 in the same direction as in the above embodiment. At this time, the developing roller 210 is disposed on the entire surface of the developing roller 210 so as to form a polishing line that becomes the order in the rotation direction of the developing roller 210.

  Next, after performing the above-described polishing processing and the like, the center portion 212 of the developing roller 210 is polished with a fine grindstone so that the polishing eyes are reversed with respect to the rotation direction of the developing roller 210. By doing in this way, the developing roller 210 which concerns on this embodiment can be manufactured easily. The polishing method is not limited to this, and can be appropriately changed as long as desired polishing eyes can be obtained.

  In the developing cartridge 20 configured as described above, the developing roller 210 rotates while the end portion 211 slides on the side seal member 140. Here, since the polishing marks 211A of the end portion 211 are in sliding contact with each other along the side seal member 140, the frictional force on the surface of the end portion 211 of the developing roller 210 can be further reduced. Therefore, the slidability at the end 211 of the developing roller 210 can be improved.

  In addition, since a part of the end portion 211 of the developing roller 210 is also located in the range where the supply roller 120 is disposed, for example, if the end portion 211 of the developing roller 210 has no polishing eye, the end portion 211 In this position, the toner cannot be sufficiently carried, and the printing ability may be lowered. However, in this embodiment, since the end 211 of the developing roller 210 also has a polishing eye 211A, even if the supply roller 120 is disposed at the position of the end 211 of the developing roller 210, the toner is sufficiently supplied at that position. It can be carried and the printing ability is maintained. Therefore, the developing roller 210 can be shortened in the left-right direction, and the entire developing cartridge 20 can be downsized.

  In the embodiment, the tip 131A of the layer thickness regulating blade 130 extends to the outside in the left-right direction than the inner end 141 of the side seal member 140. However, the present invention is not limited to this and extends to the outside in the left-right direction. It does not have to be.

  In the embodiment, the developing cartridge 10 is illustrated as the developing device of the present invention, but the present invention is not limited to this, and the developing device may be configured as a so-called process cartridge including a photosensitive drum and a developing roller.

  In the above embodiment, the present invention is applied to the developing device of the laser printer 1. However, the present invention is not limited to this, and the present invention is applied to other image forming apparatuses, for example, developing devices such as copiers and multifunction machines. May be.

DESCRIPTION OF SYMBOLS 10 Developing cartridge 20 Developing cartridge 100 Case 110 Developing roller 111 End portion 112 Center portion 112A Polishing eye 113 Boundary 120 Supply roller 120A End portion 130 Layer thickness regulating blade 131 Blade body 131A End portion 140 Side seal member 141 Inner end portion 210 Development Roller 211 End 211A Polishing eye 212 Central part 213 Boundary

Claims (6)

A housing configured to contain developer;
A developing device including a developing roller rotatably provided in the housing,
As for the polishing marks on the surface of the developing roller, the end in the axial direction of the developing roller is forward with respect to the rotating direction of the developing roller , and the central portion in the axial direction of the developing roller is with respect to the rotating direction. And a reverse developing device. A seal member disposed between the housing and the developing roller at the end of the developing roller;
A plate-like layer thickness regulating blade configured to regulate the layer thickness of the developer on the developing roller in contact with the developing roller;
2. The developing device according to claim 1, wherein a portion of the layer thickness regulating blade that contacts the developing roller extends to the outside in the axial direction from an inner end portion of the seal member in the axial direction. .   The developing device according to claim 2, wherein a portion of the layer thickness regulating blade that contacts the developing roller is formed of metal. 4. The developing device according to claim 2 , wherein an inner end portion of the seal member in the axial direction is positioned outside a boundary between the end portion and the central portion of the developing roller. A supply roller configured to supply developer to the development roller;
End of the axis direction of the supply roller, according to any one of claims 1 to 4, characterized in that located inside the boundary of the central portion and the end portion of the developing roller Development device. E Bei the supply roller configured to supply the developer to the developing roller,
End of said axial pre Symbol feed roller, to any one of claims 1 to 4, characterized in that located outside the boundary of the central portion and the end portion of the developing roller The developing device described.

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