JP2022112325A - Developing device and image forming apparatus - Google Patents

Abstract

To prevent adhesion of resin fine particles constituting toner to a developing roller due to floating of the particles, and to improve maintainability.SOLUTION: A developing device 20 comprises: a developing roller 24 that conveys a developer 100 including toner and magnetic carrier to a developing area 28; stirring and conveying rollers 22, 23 that convey the developer; and a regulation member (doctor blade 25) that regulates the layer thickness of the developer 100, and a capturing member 30 is provided adjacent to the regulation member on the upstream side of the regulation member in the direction of rotation B of the developing roller 24. The capturing member 30 has a curved surface that covers a peripheral space from the stirring and conveying roller 23 to the developing roller 24.SELECTED DRAWING: Figure 2

Description

The present invention relates to a developing device and an image forming apparatus equipped with the developing device.

2. Description of the Related Art An electrophotographic image forming apparatus develops an electrostatic latent image formed on a photosensitive drum by a developing device. Developers containing toner and magnetic carriers are widely known as developers used for visualization. In the developing device, the developer is drawn up from the developer tank to the developing roller, and the developer is conveyed to the developing area by the rotation of the developing roller. Further, there is also one in which a regulating member called a doctor blade is provided on the upstream side of the developing area in the rotating direction of the developing roller.

The regulating member is provided with a gap between it and the peripheral surface of the developing roller, and is configured to scrape excess developer from the developing roller and maintain a suitable amount of developer transported. However, the developer undergoes aging due to physical stress and the like. For example, a toner used for a two-component developer is composed of toner particles and an external additive. A toner particle (capsule toner particle) has a core toner particle and a resin coating layer (shell layer) covering the surface of the core toner particle. The resin coating layer is formed of resin fine particles, and external additives containing organic-inorganic composite fine particles (large particle size external additive) and small particle size silica or the like adhere to the surface of the toner particles. When such toner changes over time, the fine resin particles tend to scatter.

For example, Japanese Patent Application Laid-Open No. 2002-200000 discloses a developer cartridge that includes a collecting member vertically above a regulating member to collect scattered toner. The collecting member has a facing portion that faces the regulating member and forms an accommodating portion that accommodates the developer between itself and the regulating member, a first portion that extends from one end connected to the facing portion toward the regulating member, and the first portion. and a second portion having one end connected to the other end of the portion and extending toward the developer carrier.

JP 2017-156474 A

When the fine resin particles forming the toner scatter or float, the fine resin particles may adhere to the peripheral surface of the developing roller. When the fine resin particles adhere to the developing roller, they stick to each other to cause a seizure phenomenon, which increases the surface resistance of the developing roller and may reduce the adherence of toner used for development. As a result, the amount of toner transported by the developing roller is reduced, the image density of the visible image obtained by development is reduced, and scumming due to the reduced adhesion (toner is not adhered to the portion of the visible image that should not be adhered). There is a problem that an image defect such as a phenomenon that the ink adheres) occurs.

Conventionally, when such an image defect occurs, maintenance by a specialized operator is required, such as cleaning the peripheral surface by wiping off the fine resin particles stuck to the developing roller together with the toner, or replacing the developing roller. It was said.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its object is to suppress adhesion of fine resin particles constituting toner to a developing roller due to floating and to improve maintainability. Another object of the present invention is to provide a developing device capable of stably forming a high-quality image, and an image forming apparatus equipped with the developing device.

In order to achieve the above object, the present invention provides a developing roller that conveys a developer containing toner and a magnetic carrier to a developing area by rotation, and a developing roller that is arranged to face the peripheral surface of the developing roller to transfer the developer. a conveying member that conveys the developer to the developing roller; and a regulating member that regulates the layer thickness of the developer, provided facing the peripheral surface of the developing roller on the upstream side of the developing region in the rotational direction of the developing roller. A catching member is provided adjacent to the regulating member on the upstream side of the regulating member in the direction of rotation of the developing roller, and the catching member extends from the conveying member to the developing roller. It is characterized by having a curved surface that covers the surrounding space of the

A more specific configuration of the developing device is as follows. That is, in the developing device, it is preferable that the curved surface of the capturing member has a concave curved shape in a direction away from the conveying member and the developing roller. Further, it is preferable that the curved surface of the catching member has a curved shape in which a leading end portion on the developing roller side is provided close to the regulating member.

Further, in the developing device having the above configuration, it is preferable that the catching member has a surface roughness larger than that of the developing roller. Further, it is preferable that the capturing member has surface roughness that varies stepwise along the curved surface. In this case, it is more preferable that the catching member has a finer surface roughness as it approaches the end portion of the regulating member on the developing roller side.

Further, the catching member may be connected to the upstream side surface of the regulating member and a supporting member that supports the regulating member. It is preferable that the regulating member is detachably provided with respect to the regulating member.

Further, an image forming apparatus including a developing device having each of the configurations described above is also within the scope of the technical concept of the present invention. As a result, it is possible to prevent fine particles of resin contained in the developer from floating and sticking to the developing roller, thereby enabling even better image formation.

According to the present invention, it is possible to suppress sticking to the developing roller due to floating of resin fine particles contained in the developer. As a result, it is possible to maintain high image quality of formed images throughout the life.

1 is a cross-sectional view schematically showing the configuration of a main part of an image forming apparatus provided with a developing device according to an embodiment of the invention; FIG. 3 is a cross-sectional view showing a developing device provided in the image forming apparatus; FIG. FIG. 4 is an explanatory diagram showing the configuration of a capturing member provided in the developing device; FIG. 4 is an explanatory diagram showing the structure of surface roughness of the curved surface portion of the capturing member; 5 is a graph showing measurement results obtained by comparing and verifying the concentration of fine resin particles adhering to the surface with and without the capturing member.

Developing devices and image forming apparatuses according to embodiments of the present invention will be described below with reference to the drawings.

(Overview of Image Forming Apparatus)
FIG. 1 is a cross-sectional view schematically showing the configuration of the main part of an image forming apparatus 1 equipped with a developing device 20 according to an embodiment of the invention. The image forming apparatus 1 employs a two-component development method using a two-component developer containing toner and magnetic carriers, which are magnetic particles.

As illustrated, the image forming apparatus 1 includes a photosensitive drum 11 , a charger 12 , an exposure device 13 , a transfer device 14 , a cleaning device 15 , a static eliminator 16 , a fixing device 17 , a power source, and a developing device 20 . . The photosensitive drum 11 rotates counterclockwise in FIG. The rotating direction of the photosensitive drum 11 corresponds to the sub-scanning direction of the exposure device 13 . Charger 12 , exposure device 13 , development device 20 , transfer device 14 , cleaning device 15 , and static eliminator 16 are arranged in this order along the rotation direction of photoreceptor drum 11 .

As shown in FIG. 1, a sheet S, which is an example of a recording medium, is conveyed leftward in the drawing between a photosensitive drum 11 and a transfer device 14 . The fixing device 17 is arranged downstream of the transfer device 14 in the sheet S conveying direction.

The photoreceptor drum 11 includes a conductive substrate 111 rotatably supported about an axis by a drive unit (not shown) and a photoconductive layer 112 formed on the surface of the conductive substrate 111 . The conductive substrate 111 can have various shapes, such as a cylindrical shape, a columnar shape, and a thin film sheet shape. The photoconductive layer 112 is made of a material that exhibits conductivity when irradiated with light. The photosensitive drum 11 includes, for example, a cylindrical member (conductive substrate 111) made of aluminum, and amorphous silicon (a-Si) and selenium (Se) formed on the outer peripheral surface of the cylindrical member. , or a thin film (photoconductive layer 112) made of an organic optical semiconductor (OPC) can be used.

The charger 12 uniformly charges the peripheral surface of the photosensitive drum 11 . As the charger 12, for example, a charging wire such as a tungsten wire, a corona charger or a charging roller made of a metallic shield plate or a grid plate, or a charging brush is used.

The exposure device 13 irradiates the circumferential surface of the photosensitive drum 11 rotating in the sub-scanning direction with light in the main scanning direction according to image information. Thereby, the exposure device 13 forms an electrostatic latent image on the peripheral surface of the photosensitive drum 11 . As the exposure device 13, a laser, an LED (Light Emitting Diode), or the like is used.

The developing device 20 supplies toner to a developing area on the circumferential surface of the photoreceptor drum 11 by means of a developing electric field formed between the photoreceptor drum 11 and the developing device 20 . As a result, the developing device 20 visualizes the electrostatic latent image into a toner image. The developing device 20 has a bias power supply (not shown).

The transfer device 14 transfers the toner image onto the sheet S with a transfer bias applied from the power source 18 . As the transfer device 14, a transfer roller, a charging brush, a corona charger, or the like is used. The fixing device 17 fixes the toner image to the sheet S by thermally pressing the toner transferred onto the sheet S to the sheet S. As shown in FIG.

The cleaning device 15 removes toner remaining on the peripheral surface of the photosensitive drum 11 after the toner image has been transferred onto the sheet S. As shown in FIG. The cleaning device 15 has, for example, a cleaning blade. The static eliminator 16 removes charges on the peripheral surface of the photoreceptor drum 11 from which the toner has been removed.

The peripheral surface of the photosensitive drum 11 from which the charges have been removed by the static eliminator 16 is uniformly charged again by the charger 12 . An electrostatic latent image is formed on the peripheral surface of the photosensitive drum 11 by the exposure device 13 . The electrostatic latent image is turned into a toner image by developing device 20 . The toner image is transferred onto the sheet S by the transfer device 14 and fixed onto the sheet S by the fixing device 17 . Toner remaining on the peripheral surface of the photoreceptor drum 11 is removed by the cleaning device 15 , and the peripheral surface of the photoreceptor drum 11 is neutralized by the static eliminator 16 . Such an image forming process is repeated as necessary.

(developing device)
FIG. 2 is a cross-sectional view schematically showing the developing device 20 provided in the image forming apparatus 1. As shown in FIG. In addition, in FIG. 2, hatching indicating a member cross section is omitted in order to make it easier to see each constituent member in the drawing.

As shown, the developing device 20 includes a developer tank 211, two stirring members, a developing roller 24, and a regulating member in a housing 21. As shown in FIG. As the agitating member, agitating conveying rollers 22 and 23 are provided in this embodiment. Further, in this embodiment, a doctor blade 25 is provided as the regulating member.

A developer tank 211 is a container in which the developer 100 is stored. A developer (two-component developer) containing non-magnetic toner and a magnetic carrier is used as the developer 100 . The agitation conveying rollers 22 and 23 agitate the developer 100 stored in the developer tank 211 . This agitation causes friction between the toner contained in the developer 100 and the magnetic carrier, and the friction causes the non-magnetic toner to be charged.

The developing roller 24 is partially exposed to the outside of the housing 21 and arranged to face the photosensitive drum 11 rotating in the rotation direction A. As shown in FIG. The developing roller 24 is composed of a non-magnetic, cylindrical sleeve portion (not shown) rotatably supported by a shaft, and a cylindrical magnet roll disposed inside the sleeve portion and having magnetism. and The developing roller 24 rotates in the rotation direction B due to the rotation of the sleeve portion. A plurality of magnetic poles each having a single polarity are formed on the peripheral surface of the developing roller 24 due to the magnetism of the magnet roll portion.

The magnetic poles of the developing roller 24 include, for example, a main pole and a regulating pole. The main pole is a magnetic pole that prevents the magnetic carrier from separating from the peripheral surface of the developing roller 24 during development, and is formed in a developing area (area facing the photosensitive drum 11) 28 on the peripheral surface of the developing roller 24. there is A regulating pole is a magnetic pole facing the doctor blade 25 . For example, the regulating pole also functions as a scooping pole for scooping up the developer 100 stored in the developer tank 211 . The scooped developer 100 adheres to the peripheral surface of the developing roller 24 and is transported to the developing area 28 as the developing roller 24 rotates in the rotational direction B. As shown in FIG.

The sleeve portion forming the peripheral surface of the developing roller 24 is made of SUS, for example. The peripheral surface of the developing roller 24 is sandblasted. The ten-point average roughness of the peripheral surface of the developing roller 24 is set, for example, within a range of 2 μm or more and 5 μm or less.

Further, the doctor blade 25 as a regulating member is arranged close to the peripheral surface of the developing roller 24 with a gap provided on the upstream side of the developing region 28 with respect to the rotation direction B of the developing roller 24 . ing. The doctor blade 25 restricts the amount of the developer 100 that passes through the gap, thereby regulating the layer thickness of the developer.

In the exemplary embodiment, the doctor blade 25 has a blade shape that is long in the direction along the axial direction X of the developing roller 24, and the length along the axial direction X is longer than the printing area of the developing roller 24. preferably. As a material for the doctor blade 25, stainless steel, aluminum, synthetic resin, or the like can be used. The outer diameter φ of the developing roller 24 is, for example, about 18 mm, and the width of the developing roller 24 is set to a length that can correspond to, for example, A4 size.

In the developing device 20 , magnetic force is generated in the magnetic carrier contained in the developer 100 in the developer tank 211 due to the action of the magnetic poles. Due to this magnetic force, the magnetic carrier adheres to the peripheral surface of the developing roller 24 along with the non-magnetic toner. As a result, the developer 100 is pumped up from the developer tank 211 on the upstream side of the doctor blade 25 . As the developing roller 24 rotates, the scooped up developer 100 passes through the gap between the doctor blade 25 and the peripheral surface of the developing roller 24 and is conveyed to the developing area 28 .

The cover portion 27 is a member that contacts along the main scanning direction orthogonal to the rotation direction A of the photosensitive drum 11 , and covers the space from the doctor blade 25 to the photosensitive drum 11 . Frictional heat is generated at the tip of the doctor blade 25 and warms the air around the tip of the doctor blade 25 . As a result, an updraft is generated, and the warm air rises. As a result, the toner is separated from the developer 100 that has passed the doctor blade 25 and floats downstream in the rotational direction B of the developing roller 24 . ing.

In particular, the toner used in the two-component developer contains toner particles and an external additive, and the toner particles (capsule toner particles) consist of core toner particles and a resin coating layer covering the surface of the core toner particles. (shell layer). The resin coating layer is formed of resin fine particles, and external additives containing organic-inorganic composite fine particles (large particle size external additive) and small particle size silica or the like adhere to the surface of the toner particles. When such toner deteriorates with time, there is a problem that the fine resin particles of the toner particles tend to float.

It has been confirmed that the image sticking phenomenon that occurs in the developing roller 24 as described above occurs remarkably in the gap between the tip of the doctor blade 25 that regulates the developer 100 and the developing roller 24 .

(capturing member)
In contrast, in the developing device 20 according to the present embodiment, the fine resin particles floating in the gap between the tip of the doctor blade 25 and the developing roller 24 adhere to and adhere to the fine resin particles. is provided.

As shown in FIG. 2, a capture member 30 is provided adjacent to the doctor blade 25 on the upstream side of the doctor blade 25 in the rotation direction B of the developing roller 24 . FIG. 3 is an explanatory diagram showing the configuration of the capturing member 30. As shown in FIG.

As illustrated, the doctor blade 25 has a first side surface 25a on the upstream side in the rotational direction B of the developing roller 24, a second side surface 25c on the downstream side in the rotational direction B of the developing roller 24, and a leading end portion 25 b that forms a gap facing the peripheral surface of the developing roller 24 . The doctor blade 25 is supported by a support member 26 at the end opposite to the tip 25b. As shown in FIG. 2, support member 26 is fixed to housing 21 .

The catching member 30 is connected to the upstream first surface 25 a of the doctor blade 25 and the support member 26 that supports the doctor blade 25 . In the exemplary embodiment, as shown in FIG. 3, the capturing member 30 is detachably attached to the supporting member 26 and includes a curved surface portion 31, a connecting portion 32, and a mounting member 33. As shown in FIG.

The curved surface portion 31 has a curved surface. The connection portion 32 has a base portion 321 connected to one end portion of the mounting member 33 and an end portion opposite to the base portion 321 connected to the tip portion 315 of the curved surface portion 31 . A base portion 314 of the curved surface portion 31 is connected to the other end portion of the mounting member 33 .

At least the curved surface portion 31 of the capturing member 30 is formed of a metal plate. The curved surface portion 31 and the connection portion 32 may be formed of an integral metal plate. Examples of such metal plate materials include metal plate materials such as aluminum and stainless steel (for example, SUS). The curved surface portion 31 and the connection portion 32 are not limited to being made of a metal plate material, and may be an integral synthetic resin molded product.

As shown in FIG. 2 , the curved shape of the curved surface portion 31 is a concave shape that is recessed in a direction away from the agitating-conveying roller 23 and the developing roller 24 . Further, as shown in FIG. 3 , the curved surface portion 31 is formed in a curved shape with a constant curvature from the base portion 314 to the tip portion 315 . For example, the curved portion 31 preferably has a curvature of 50% to 200% of the curvature of the developing roller 24 . Therefore, the curved surface portion 31 may have the same curvature as that of the developing roller 24. For example, when the developing roller 24 has a diameter of φ18, the curvature R of the curved surface portion 31 is preferably 9-10.

The curved surface portion 31 has a curved shape in which a tip portion 315 on the developing roller 24 side is provided close to the tip portion 25 b of the doctor blade 25 . Further, the curved surface portion 31 is provided so as to cover the surrounding space from the agitating/conveying roller 23 to the developing roller 24 .

As shown in FIG. 3, the tip portion 315 where the curved surface portion 31 and the connecting portion 32 are coupled is arranged along the first surface 25a of the doctor blade 25 and is close to or in contact with the tip portion 25b of the doctor blade 25. is doing. Further, the tip portion 315 is closer to the tip portion 25 b of the doctor blade 25 than to the peripheral surface of the developing roller 24 between the tip portion 25 b of the doctor blade 25 and the peripheral surface of the developing roller 24 . The tip portion 315 is provided so as to be separated from the peripheral surface of the developing roller 24 .

As shown in FIG. 2, assuming a straight line L connecting the axis of the developing roller 24 and the axis of the agitation-conveying roller 23, the tip 315 of the curved surface portion 31 is closer to the straight line L than the base 314. is provided. The distance from the base portion 314 to the tip portion 315 of the curved portion 31 (length in the circumferential direction of the curved surface) is not particularly limited, but should be equal to or larger than the radius of the developing roller 24 or within the diameter of the developing roller 24. is preferred.

When viewed from above, the curved surface portion 31 is arranged so as to straddle the developing roller 24 and the agitating/conveying roller 23 . In the exemplary embodiment, the curved surface portion 31 is arranged so as to cover the agitating/conveying roller 23 more widely than the developing roller 24 . More preferably, the base portion 314 side of the curved surface portion 31 is provided so as to cover the upper side of the agitating-conveying roller 23 , and is arranged closer to the agitating-conveying roller 22 than the axial center of the agitating-conveying roller 23 . Note that the curved surface portion 31 is not limited to being formed in a curved shape entirely from the base portion 314 to the tip portion 315, and may be formed such that a portion of the region from the base portion 314 to the tip portion 315 is curved.

As shown in FIG. 3, the capturing member 30 is configured as an integral member by connecting the curved surface portion 31 and the connecting portion 32 to the mounting member 33 in advance. The catching member 30 is detachably attached to the supporting member 26 or the doctor blade 25 . The mounting member 33 is provided so that one end thereof contacts the first surface 25 a of the doctor blade 25 . The mounting member 33 is provided with a mounting piece 331 projecting therefrom as a fixed portion to the support member 26 . The mounting piece 331 extends on the side of the mounting member 33 opposite to the curved surface portion 31 .

As shown in the figure, the attachment member 33 is connected to the support member 26 while the connecting portion 32 of the capture member 30 is slid along the first surface 25a of the doctor blade 25. By stacking the mounting pieces 331 and fixing them with screws 332, the capturing member 30 can be mounted. The catching member 30 is provided so that the curved surface portion 31 covers the surrounding space from the agitating/conveying roller 23 to the developing roller 24 . Also, the capture member 30 can be easily removed from the support member 26 by reversing this procedure.

The catching member 30 is formed such that the surface roughness of the curved surface portion 31 is equal to or rougher than the surface roughness of the peripheral surface of the developing roller 24 . For example, the sleeve portion of the developing roller 24 is sandblasted as described above, and has a ten-point average roughness of 2 μm or more and 5 μm or less. On the other hand, the curved surface portion 31 is formed to have a ten-point average roughness of 3 μm or more and 15 μm or less, more preferably 4 μm or more and 12 μm or less.

Furthermore, in the present embodiment, it is preferable that the curved surface portion 31 of the capturing member 30 has a surface roughness that varies stepwise. 4A and 4B are explanatory diagrams showing the structure of the surface roughness of the curved surface portion 31 of the catching member 30. The right side of the figure shows the catching member 30 as viewed in the axial direction X as shown in FIG. The middle left side shows the curved surface portion 31 of the capturing member 30 as viewed from the direction intersecting the axial direction X. As shown in FIG.

As shown in the figure, the curved surface portion 31 of the capturing member 30 is formed with, for example, three different levels of surface roughness, and the surface roughness becomes finer in stages as the doctor blade 25 approaches the tip 315 on the developing roller 24 side. is provided as follows.

In the illustrated configuration, the surface roughness Rz of the first curved surface 311 on the tip portion 315 side of the curved surface portion 31 is 4 to 5 μm, and the surface roughness Rz of the central second curved surface 312 is 6 to 8 μm, The maximum surface roughness Rz of the third curved surface 313 on the base 314 side is 10 to 12 μm. Such surface roughness Rz of the curved surface portion 31 is proportional to the ability to capture floating resin fine particles. The larger the surface roughness Rz, the easier it is for the floating resin particles to adhere to the surface, and the more efficiently the resin particles free and floating from the toner can be removed.

As shown in FIG. 2 , the capturing member 30 is attached to the support member 26 so that the curved surface portion 31 covers the upper portion of the surrounding space from the agitating/conveying roller 23 to the developing roller 24 . Here, since the third curved surface 313 of the curved surface portion 31 has the largest surface roughness Rz, it is possible to quickly remove the fine resin particles on the upstream side in the rotation direction B of the developing roller 24 .

That is, for the developer 100 in the refreshed state drawn up from the agitating/conveying roller 23 , the fine resin particles released from the toner are captured by contacting the surface of the curved surface portion 31 of the capturing member 30 , and captured on the upstream side of the doctor blade 25 . Floating amount can be reduced. As a result, the amount of fine resin particles reaching the gap between the doctor blade 25 and the developing roller 24 can be reduced. Therefore, it is possible to suppress adhesion of fine resin particles, which is the cause of the sticking phenomenon of the developing roller 24, and to solve the conventional problems such as an increase in the surface resistance of the developing roller and a decrease in adhesion of toner used for development. becomes possible.

In addition, the curved surface portion 31 having such a stepped surface roughness Rz has a smoothly curved shape recessed in a direction away from the agitating-conveying roller 23 and the developing roller 24, thereby allowing the developing roller 24 to rotate. It is possible to smoothly convey the developer 100 to the development area 28 without stopping the flow of the conveyance of the developer 100 to the development area 28 accompanying the rotation in the direction B. Therefore, stress on the developer 100 can be reduced.

In addition, the capture member 30 is provided detachably with respect to the support member 26 . Therefore, it is possible to remove the capturing member 30 at an appropriate timing to clean the fine resin particles adhering to the curved surface portion 31, thereby improving maintainability.

FIG. 5 is a graph showing the measurement results of verifying the presence or absence of the image sticking phenomenon in the developing roller 24 as acceleration actual machine verification. showing.

In this accelerated actual machine verification, the toner concentration was set high, and when a solid band pattern with a high printing rate was continuously printed on the sheet S, it was observed how adhesion of the fine resin particles would change. Specifically, as shown in Table 1, the developing roller 24 (without the catching member) when the catching member 30 is not attached, the developing roller 24 (with the catching member) when the catching member 30 is attached, and the catching member 24 (with the catching member) The adhered density of the fine resin particles to the curved surface portion 31 (capturing member) of the member 30 was measured and quantified. The adhesion density was measured with a reflection spectrodensitometer (manufactured by SDG Co., Ltd., X-Rite).

As shown in FIG. 5, as the number of printed sheets increases, the adhesion density of the fine resin particles on each member increases. Here, although the resin fine particles stick to each surface, the rate of increase in adhesion concentration of the resin fine particles is greater in the case without the capturing member (○) than in the case with the capturing member (□). It is noticeable. In particular, it can be seen that the adherence density of the fine resin particles on the peripheral surface of the developing roller 24 is low when the trapping member is provided, and the adherence density is higher when the trapping member is not provided.

Further, as shown in the figure, an increase in adhesion density of the fine resin particles was also observed on the surface (curved surface portion 31) of the capturing member. As a result, it can be seen that the floating resin fine particles adhered to and were captured by the capture member 30 on the upstream side of the doctor blade 25 .

As described above, in the developing device 20 according to the present embodiment, the catching member 30 is provided. It is possible to suppress contamination of the peripheral surface. As a result, problems such as a decrease in the amount of toner transported and a decrease in image density can be resolved, and more stable and high-quality image formation can be achieved, and maintainability can also be improved.

The image forming apparatus 1 including the developing device 20 as described above may be a color image forming apparatus or a monochrome image forming apparatus. The image forming apparatus 1 may be a multifunction machine having a copying function, a printer function, a scanner function, a facsimile function, and the like.

The invention is not limited to the embodiments described above, but can be implemented in various other forms. Therefore, the above embodiment is merely an example in all respects and should not be construed in a restrictive manner. The scope of the present invention is indicated by the claims and is not restricted by the text of the specification. Furthermore, all modifications and changes within the equivalent scope of claims are within the scope of the present invention.

1 Image forming apparatus 11 Photoreceptor drum 20 Developing device 21 Housing 22 Stirring conveying roller (conveying member)
23 agitating and conveying roller (conveying member)
24 developing roller 25 doctor blade (regulating member)
26 support member 30 capture member 31 curved surface portion (curved surface)
311 First curved surface 312 Second curved surface 313 Third curved surface 314 Base portion 315 Tip portion 32 Connecting portion 33 Mounting member

Claims (11)

a developing roller that conveys a developer containing toner and a magnetic carrier to a developing area by rotation;
a conveying member arranged to face the peripheral surface of the developing roller and conveying the developer to the developing roller;
A developing device comprising: a regulating member that is provided facing the peripheral surface of the developing roller upstream of the developing region in the rotational direction of the developing roller and that regulates the layer thickness of the developer,
A capturing member is provided adjacent to the regulating member on the upstream side of the regulating member in the direction of rotation of the developing roller,
The developing device, wherein the capturing member has a curved surface covering a surrounding space from the conveying member to the developing roller. The developing device according to claim 1,
The developing device, wherein the curved surface of the catching member has a concave curved shape in a direction away from the conveying member and the developing roller. 3. The developing device according to claim 1, wherein
The developing device, wherein the curved surface of the catching member has a curved shape in which a leading end portion on the developing roller side is provided close to the regulating member. In the developing device according to any one of claims 1 to 3,
The developing device, wherein the catching member has a surface roughness larger than that of the developing roller. In the developing device according to claim 4,
The developing device, wherein the capturing member has a surface roughness that varies stepwise along the curved surface. In the developing device according to claim 5,
The developing device, wherein the surface roughness of the catching member becomes finer as it approaches a leading end portion of the regulating member on the developing roller side. In the developing device according to any one of claims 4 to 6,
The developing device, wherein the capturing member has a surface roughness of 3 μm or more and 15 μm or less. In the developing device according to any one of claims 1 to 7,
A developing device, wherein at least the curved surface of the capturing member is formed of a metal plate. In the developing device according to any one of claims 1 to 8,
The developing device, wherein the capturing member is connected to the upstream side surface of the regulating member and a supporting member that supports the regulating member. In the developing device according to claim 9,
The developing device, wherein the capturing member is detachably attached to the supporting member or the regulating member. An image forming apparatus comprising the developing device according to any one of claims 1 to 10.

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