阅读说明：本技术 显影装置和图像形成设备 (Developing device and image forming apparatus ) 是由 中岛由高 吉井朋幸 玉泽纪洋 尾崎善史 加藤正则 仓本新一 于 2019-11-05 设计创作，主要内容包括：一种显影装置和图像形成设备。该显影装置包括：显影剂载体,其上设定有吸引区域,所述吸引区域是吸引包括色调剂和载体的显影剂的区域,并且所述显影剂载体在所述吸引区域中承载所述显影剂,所述显影剂待供应至形成有静电潜像的图像载体；调节构件,其调节所述显影剂,以使得由所述显影剂载体承载预定量的所述显影剂；以及形成单元,其位于所述调节构件的上游并且在所述吸引区域中形成第一区域和第二区域,所述第一区域限制供应至所述显影剂载体的显影剂的流动,所述第二区域位于所述第一区域和所述调节构件之间并且与所述第一区域相比不限制所述显影剂的流动。(A developing device and an image forming apparatus. The developing device includes: a developer carrier on which an attraction area is set, the attraction area being an area that attracts a developer including a toner and a carrier, and the developer carrier carrying the developer in the attraction area, the developer to be supplied to an image carrier on which an electrostatic latent image is formed; a regulating member that regulates the developer so that a predetermined amount of the developer is carried by the developer carrier; and a forming unit that is located upstream of the regulating member and forms a first region that restricts a flow of the developer supplied to the developer carrier and a second region that is located between the first region and the regulating member and does not restrict the flow of the developer compared to the first region in the attraction region.)

1. A developing device, comprising:

a developer carrier on which an attraction area is set, the attraction area being an area that attracts a developer including a toner and a carrier, and the developer carrier carrying the developer in the attraction area, the developer to be supplied to an image carrier on which an electrostatic latent image is formed;

a regulating member that regulates the developer so that a predetermined amount of the developer is carried by the developer carrier; and

a forming unit that is located upstream of the regulating member and forms a first region that restricts a flow of the developer supplied to the developer carrier and a second region that is located between the first region and the regulating member and does not restrict the flow of the developer compared to the first region in the attraction region.

2. A developing device according to claim 1, further comprising:

a restricting unit that restricts movement of the developer removed from the developer carrier to the attraction area.

3. A developing device according to claim 2, wherein said regulating unit includes a first member that forms said first region in said forming unit and has a removal-side end portion that is arranged closer to said regulating member than a removal-side tangent line of said developer carrier that extends in the up-down direction.

4. A developing device according to claim 2, wherein said regulating unit includes a guide member that is located upstream of a first region forming portion that forms said first region in said forming unit, and that guides said removed developer to a path along which said developer that is formed by rotation of each of a plurality of rotating members and is to be supplied to said developer carrier is conveyed while being stirred.

5. A developing device according to claim 4, wherein said first region forming portion and said guide member are integrally formed.

6. A developing device according to claim 1, further comprising:

a guide unit that guides the developer removed from the developer carrier to a path along which the developer formed by rotation of each of the plurality of rotating members and to be supplied to the developer carrier is conveyed while being agitated, with a driving force.

7. A developing device according to claim 6, wherein said guiding unit guides said removed developer by using another rotating member different from said plurality of rotating members, and discharges said removed developer to said path.

8. An image forming apparatus, comprising:

an image carrier on which an electrostatic latent image is formed;

a developing unit that develops the electrostatic latent image formed on the image carrier into a toner image;

a transfer unit that transfers the toner image formed by the developing unit onto a recording medium; and

a fixing unit that fixes the toner image transferred onto the recording medium to the recording medium,

wherein the developing unit includes:

a developer carrier on which an attraction area is set, the attraction area being an area that attracts a developer including a toner and a carrier, and the developer carrier carrying the developer in the attraction area, the developer to be supplied to the image carrier on which the electrostatic latent image is formed;

a regulating member that regulates the developer so that a predetermined amount of the developer is carried by the developer carrier; and

a forming unit that is located upstream of the regulating member and forms a first region that restricts a flow of the developer supplied to the developer carrier and a second region that is located between the first region and the regulating member and does not restrict the flow of the developer compared to the first region in the attraction region.

Technical Field

The present disclosure relates to a developing device and an image forming apparatus.

Background

For example, japanese unexamined patent application publication No. 2012-014087 discloses a developing device including a member that blocks supply of a developer at a position upstream of a developing roller and has a slit through which the developer is supplied to the developing roller.

Disclosure of Invention

In the case where the developer regulated by the regulating member is attracted and carried on the developer carrier by a magnetic force, and the amount of the developer is reduced by reducing the magnetic force, the layer formation stability of the developer may be adversely affected.

Therefore, it is an object of the present disclosure to suppress an adverse effect on layer formation stability of a developer as compared with a case where a forming unit is not provided, the forming unit forming a first region that restricts a flow of the developer supplied to a developer carrier and a second region that is located between the first region and a regulating member in a suction region, and the second region does not restrict the flow of the developer as compared with the first region.

According to a first aspect of the present disclosure, there is provided a developing device including: a developer carrier on which an attraction area is set, the attraction area being an area that attracts a developer including a toner and a carrier, and the developer carrier carrying the developer in the attraction area, the developer to be supplied to an image carrier on which an electrostatic latent image is formed; a regulating member that regulates the developer so that a predetermined amount of the developer is carried by the developer carrier; and a forming unit that is located upstream of the regulating member and forms a first region that restricts a flow of the developer supplied to the developer carrier and a second region that is located between the first region and the regulating member and does not restrict the flow of the developer compared to the first region in the attraction region.

According to a second aspect of the present disclosure, there is provided the developing device according to the first aspect, further comprising: a restricting unit that restricts movement of the developer removed from the developer carrier to the attraction area.

According to a third aspect of the present disclosure, there is provided the developing device according to the second aspect, wherein the regulating unit includes a first member that forms the first region in the forming unit and has a removal-side end portion that is arranged closer to the regulating member than a removal-side tangent line of the developer carrier that extends in the up-down direction.

According to a fourth aspect of the present disclosure, there is provided the developing device according to the second aspect, wherein the regulating unit includes a guide member that is located upstream of a first region forming portion that forms the first region in the forming unit and that guides the removed developer to a path along which the developer that is formed by rotation of each of a plurality of rotating members and is to be supplied to the developer carrier is conveyed while being stirred.

According to a fifth aspect of the present disclosure, there is provided the developing device according to the fourth aspect, wherein the first region forming portion and the guide member are integrally formed.

According to a sixth aspect of the present disclosure, there is provided the developing device according to the first aspect, further comprising: a guide unit that guides the developer removed from the developer carrier to a path along which the developer formed by rotation of each of the plurality of rotating members and to be supplied to the developer carrier is conveyed while being agitated, with a driving force.

According to a seventh aspect of the present disclosure, there is provided the developing device according to the sixth aspect, wherein the guide unit guides the removed developer by using another rotating member different from the plurality of rotating members, and discharges the removed developer to the path.

According to an eighth aspect of the present disclosure, there is provided an image forming apparatus comprising: an image carrier on which an electrostatic latent image is formed; a developing unit that develops the electrostatic latent image formed on the image carrier into a toner image; a transfer unit that transfers the toner image formed by the developing unit onto a recording medium; and a fixing unit that fixes the toner image transferred onto the recording medium to the recording medium. The developing unit includes: a developer carrier on which an attraction area is set, the attraction area being an area that attracts a developer including a toner and a carrier, and the developer carrier carrying the developer in the attraction area, the developer to be supplied to the image carrier on which the electrostatic latent image is formed; a regulating member that regulates the developer so that a predetermined amount of the developer is carried by the developer carrier; and a forming unit that is located upstream of the regulating member and forms a first region that restricts a flow of the developer supplied to the developer carrier and a second region that is located between the first region and the regulating member and does not restrict the flow of the developer compared to the first region in the attraction region.

According to the first aspect, it is possible to suppress an adverse effect on the layer formation stability of the developer as compared with a case where the forming unit is not provided, the forming unit forming the first region that restricts the flow of the developer supplied to the developer carrier and the second region that is located between the first region and the regulating member and does not restrict the flow of the developer as compared with the first region in the attraction region.

According to the second aspect, compared to the case where the restricting unit that restricts the movement of the removed developer to the attraction area is not provided, the removed developer can be prevented from being attracted again to the developer carrier.

According to the third aspect, compared to the case where the first member having the removing-side end portion arranged closer to the regulating member than the removing-side vertical tangent of the developer load is not provided, the removed developer can be prevented from being attracted again.

According to the fourth aspect, compared with the case where the guide member that guides the removed developer to the path along which the developer formed by the rotation of each of the plurality of rotating members and to be supplied to the developer carrier is conveyed while being agitated is not provided, the removed developer can be prevented from being attracted again.

According to the fifth aspect, the number of members can be reduced as compared with the case where the first region forming portion and the guide member are not integrally formed.

According to the sixth aspect, the developer removed from the developer carrier can be moved smoothly, as compared with a case where a guide member that guides the removed developer by using a driving force to a path along which the developer to be supplied to the developer carrier is conveyed while being agitated is not provided.

According to the seventh aspect, the distance along which the developer is agitated or the time taken for the developer to be agitated can be reliably extended, as compared with the case where a structure for guiding the developer by using another rotary member different from the plurality of rotary members and discharging the removed developer to the path is not provided.

According to the eighth aspect, it is possible to suppress an adverse effect on the layer formation stability of the developer as compared with a case where the forming unit is not provided, the forming unit forming the first region that restricts the flow of the developer supplied to the developer carrier and the second region that is located between the first region and the regulating member in the attraction region, and the second region that does not restrict the flow of the developer as compared with the first region.

Drawings

An exemplary embodiment of the present disclosure will be described in detail based on the following drawings, in which:

fig. 1 shows a general configuration diagram of an image forming apparatus;

fig. 2 illustrates a developing device;

fig. 3 illustrates a developer attracting region;

FIG. 4 illustrates the flow of developer to the developer roller;

fig. 5 illustrates the flow of developer removed from the developing roller; and

fig. 6 shows a developing device according to a modification.

Detailed Description

Hereinafter, one exemplary embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

Fig. 1 shows an overall structure of an image forming apparatus 1. Specifically, fig. 1 shows the image forming apparatus 1 as seen from the front side of the image forming apparatus 1.

The image forming apparatus 1 includes an image forming unit 10, a sheet supply unit 20, and a fixing unit 30.

The image forming unit 10 forms a toner image on a sheet P, which is an example of a recording medium, by using an electrophotographic method. The sheet supply unit 20 supplies the sheet P to the image forming unit 10. The fixing unit 30 fixes the toner image (i.e., image) formed on the sheet P by the image forming unit 10 to the sheet P.

The image forming unit 10 includes a photosensitive drum 11 that rotates in the direction indicated by the arrow a. The image forming unit 10 further includes a charging roller 12, an exposure device 13, a developing device 14, a transfer roller 15, and a cleaning device 16.

The photosensitive drum 11 as an embodiment of the image carrier is constituted by a cylindrical body. A photosensitive layer (not shown) is formed on the surface of the cylinder.

The charging roller 12 is constituted by a conductive rubber roller or the like, and charges the photosensitive drum 11.

The exposure device 13 exposes the photosensitive drum 11, which has been charged by the charging roller 12, to light emitted from a light source such as a laser light source or a Light Emitting Diode (LED), and forms an electrostatic latent image on the surface of the photosensitive drum 11.

The developing device 14, which is an embodiment of a developing unit, applies toner having a predetermined color to the surface of the photosensitive drum 11, and develops an electrostatic latent image formed on the photosensitive drum 11 by using the toner. Thus, in the present exemplary embodiment, a toner image is formed on the surface of the photosensitive drum 11.

The developing device 14 contains developer therein. The developer in the present exemplary embodiment is a two-component developer, which is composed of a magnetic carrier and a color toner.

Further, the present exemplary embodiment includes a developer container 19, and the developer container 19 contains developer to be supplied to the developing device 14. In the present exemplary embodiment, new developer is supplied from the developer container 19 to the developing device 14 via a developer conveying path (not shown).

The transfer roller 15 as an embodiment of the transfer unit is constituted by a conductive rubber roller or the like.

In the present exemplary embodiment, the transfer roller 15 and the photosensitive drum 11 face each other at the transfer region T. The toner image on the surface of the photosensitive drum 11 (i.e., the toner image carried by the photosensitive drum 11) is transferred to the sheet P at the transfer area T.

The cleaning device 16 includes a contact member 16A, and the contact member 16A is arranged in contact with the photosensitive drum 11. The cleaning device 16 removes substances such as toner attached to the surface of the photoconductive drum 11.

In the present exemplary embodiment, the transfer roller 15 transfers the toner image to the sheet P. A structure may be used instead in which the transfer roller 15 transfers the toner image to an intermediate transfer belt (not shown).

The sheet supply unit 20 includes a sheet container 21 that accommodates sheets P and a feeding mechanism 22 that feeds the sheets P from the sheet container 21.

Further, the present exemplary embodiment includes a sheet conveying mechanism 23, and the sheet conveying mechanism 23 conveys the sheet P, which has been fed from the sheet supply unit 20, through the transfer area T and the fixing unit 30.

The fixing unit 30, which is an embodiment of the fixing unit, includes a pair of rotating bodies 31, and the pair of rotating bodies 31 rotate while contacting each other.

A heater (not shown) is disposed in one of the pair of rotating bodies 31.

In the fixing unit 30, the pair of rotating bodies 31 presses and heats the sheet P, and the toner image on the sheet P is fixed to the sheet P.

An image forming operation by the image forming apparatus 1 will be described.

In the image forming unit 10, the charging roller 12 charges the photosensitive drum 11, and the photosensitive drum 11 rotates in the direction of arrow a. Next, the exposure device 13 exposes the surface of the photosensitive drum 11, and forms an electrostatic latent image corresponding to image information formed on the surface of the photosensitive drum 11.

Subsequently, the developing device 14 develops the electrostatic latent image, and forms a toner image corresponding to the electrostatic latent image on the surface of the photosensitive drum 11.

As the photosensitive drum 11 rotates, the toner image formed on the photosensitive drum 11 moves toward the transfer region T. The sheet P fed from the sheet supply unit 20 is conveyed to the transfer area T by the sheet conveying mechanism 23.

At the transfer area T, the toner image on the photosensitive drum 11 is transferred to the conveyed sheet P. Subsequently, the sheet P to which the toner image has been transferred is heated and pressed by passing through the fixing unit 30, and the toner image is fixed to the sheet P.

Fig. 2 shows the developing device 14.

The developing device 14 includes a container unit 141 that contains developer (not shown). The tank unit 141 is constituted by a tank case 142, and the tank case 142 is made of resin.

The container case 142 of the developing device 14 is arranged to extend in a direction perpendicular to the plane of fig. 2, which is a direction from the front side toward the rear side of the image forming apparatus 1 (see fig. 1). The reservoir housing 142 includes a distal end portion (not shown) in a rear portion thereof and a front end portion (not shown) in a front portion thereof.

The container case 142 has an opening 143 in a portion thereof facing the photosensitive drum 11 (see fig. 1). A developing roller 144 is disposed in the opening 143, and the developing roller 144 applies the developer to the surface of the photosensitive drum 11.

The developing roller 144 as an example of the developer carrier has a cylindrical shape and extends in a direction from the front side toward the rear side of the image forming apparatus 1. In other words, the developing roller 144 is arranged to extend in the longitudinal direction of the developing device 14.

The developing roller 144 includes: a developing sleeve 144A which is constituted by a cylindrical body and rotates; and a magnet roller 144B disposed inside the developing sleeve 144A.

The developing sleeve 144A is made of metal such as stainless steel. The developing sleeve 144A rotates in the direction of arrow 2A in fig. 2.

Also, in the present exemplary embodiment, the developing sleeve 144A and the photosensitive drum 11 are rotated so that the developing sleeve 144A and the photosensitive drum 11 move in the same direction at the facing area TK (see fig. 1) where the developing roller 144 and the photosensitive drum 11 face each other.

The developing device 14 includes a layer regulating member 145, and the layer regulating member 145 regulates the thickness of the layer of the developer to be carried by the developing roller 144. The layer regulating member 145 is made of metal. The layer regulating member 145 is an example of such a regulating member that regulates the developer so that a predetermined amount of the developer is carried by the developing roller 144.

As shown in fig. 2, the developing device 14 includes a first conveying member 146 and a second conveying member 147 that convey the developer.

A first conveying member 146 and a second conveying member 147, which are embodiments of a plurality of rotating members, are arranged at positions opposite to the positions of the photosensitive drums 11 (see fig. 1) with respect to the developing rollers 144.

The first conveyance member 146 has a rotation axis parallel to the rotation axis of the rotating developing sleeve 144A. The first conveying member 146 rotates about its rotational axis and transfers the developer in the container unit 141.

In developing device 14 structured as described above, new toner supplied from developer container 19 or toner to which a very small amount of carrier is added is conveyed in a circulating manner between first conveying member 146 and second conveying member 147 while being stirred. More specifically, by transferring the developer through the connection holes formed in both end portions of the partition wall extending in the axial direction, the developer that has been agitated by the first conveyance member 146 is agitated by the second conveyance member 147, and can be further agitated by the first conveyance member 146. In the developing device 14, a circulation path along which the developer circulates in the axial direction by the rotation of each of the first conveying member 146 and the second conveying member 147 is formed.

The developing device 14 includes a third conveying member 149 located above the first conveying member 146. The third transmission member 149 is an embodiment of another rotation member.

A conveying path formed by the rotation of the third conveying member 149 is connected to the circulating path. The third conveying member 149 receives the recovered developer, which is the developer removed and recovered from the developing roller 144, and the toner from the developer container 19 or the toner to which a very small amount of carrier is added. Then, the third conveying member 149 conveys the toner and the recovered developer while stirring the mixture of the toner and the recovered developer, and discharges the mixture to the first conveying member 146 in the circulation path.

Therefore, in the present exemplary embodiment, the collected developer is agitated and conveyed by the third conveying member 149 in the axial direction together with the new developer. Further, the recovered developer and the new developer are further stirred and conveyed by the first conveying member 146 and the second conveying member 147. Therefore, a distance along which the developer is agitated or a time taken to agitate the developer is increased as compared with a case where the third conveying member 149 is not provided.

The developing roller 144, the layer regulating member 145, the first conveying member 146, the second conveying member 147, and the third conveying member 149 are arranged substantially parallel to the photosensitive drum 11 (see fig. 1). The present exemplary embodiment includes a first conveying member 146, a second conveying member 147, and a third conveying member 149 as members for agitating and conveying the developer. However, the structure of the developing device 14 is not limited thereto. It is contemplated that the exemplary structure includes the first transfer member 146 and the second transfer member 147 without the third transfer member 149.

Next, the collected developer conveying unit 40 will be described, and the collected developer conveying unit 40 conveys the collected developer of the developing roller 144 to the third conveying member 149 in the developing device 14. In an exemplary structure not including the third conveying member 149, the recovered developer conveying unit 40 conveys the recovered developer of the developing roller 144 to the first conveying member 146 or the second conveying member 147.

As shown in fig. 2, an upstream portion of the recovered developer conveying unit 40 has a curved surface 42. The curved surface 42 is downwardly convex. The curved surface 42 is a surface for the recovered developer, so that the recovered developer can be smoothly transferred from the developing roller 144 to the third conveying member 149.

As shown in fig. 2, the downstream portion of the recovered developer conveying unit 40 has a conveying surface 43, and the conveying surface 43 conveys the recovered developer to the third conveying member 149. In the present exemplary embodiment, the conveying surface 43 includes an inclined surface 44, and the inclined surface 44 allows the recovered developer to fall down along its slope. The inclined surface 44 is inclined substantially linearly. The recovered developer slides along the inclined surface 44 toward the third conveying member 149 by gravity.

In the present exemplary embodiment, the curved surface 42 and the inclined surface 44 are formed in one member 45. However, the curved surface 42 and the inclined surface 44 may be formed in different members.

The recovered developer conveying unit 40 is an embodiment of a guide unit.

Fig. 3 is a partially enlarged view of fig. 2, showing the developer attracting area 50.

The developing roller 144 of the developing device 14 has a plurality of magnetic poles (not shown) arrayed in the circumferential direction of the magnet roller 144B. Therefore, as shown by the thick line in fig. 3, the distribution of the magnetic attractive force in the direction perpendicular to the surface of the developing roller 144 is set. The developer attracting area 50 is an area inside the distribution of the magnetic attractive force, in which the developer can be attracted to the developing roller 144. The developer attracting area 50, which is an example of the attracting area, is set by the position and type of the plurality of magnetic poles arranged in the developing roller 144. Therefore, the region and the magnetic force necessary for achieving sufficient layer formation stability and sufficient image quality stability are reliably obtained.

The developing device 14 includes a regulating member 51 disposed upstream of the layer regulating member 145. The restriction member 51, which is an embodiment of the forming unit, partially restricts the flow of the developer supplied to the developing roller 144. The restriction member 51 may be made of a non-magnetic material and may have a film-like shape.

The restriction member 51 has a surface 51a facing the developing roller 144 and intersecting the developer attracting region 50 (inside of the thick line). The upstream portion of the surface 51a is located outside the developer attracting region, and the downstream portion of the surface 51a is located inside the developer attracting region.

Fig. 4 is a partially enlarged view of fig. 3, illustrating the flow of the developer to the developing roller 144.

As shown in fig. 4, the developing device 14 includes a blocking member 52, the blocking member 52 being disposed between the restricting member 51 and the layer regulating member 145. The developing device 14 has a supply port 53, the supply port 53 is formed between the restricting member 51 and the blocking member 52, and the developer is supplied to the developing roller 144 via the supply port 53. Due to the presence of the supply port 53, a flow of the developer is formed in a downstream area of the restriction member 51 (see an arrow in fig. 3 or 4). In the present exemplary embodiment, the blocking member 52 together with the restricting member 51 is an example of forming a unit.

The restriction member 51 and the blocking member 52 form a plurality of areas different from each other in the developer attracting area 50 with respect to the flow of the developer supplied to the developing roller 144. That is, the restricting member 51 and the blocking member 52 form: a first region 54a that restricts the flow of the developer; and a second region 54b that does not restrict the flow of the developer. The second region 54b is located downstream of the first region 54a in the rotational direction of the developing roller 144. The second area 54b is located on the outer circumferential surface of the developing roller 144 between the first area 54a and the layer regulating member 145.

Although the first area 54a can attract the developer, the first area 54a is an area not used for attracting the developer to the developing roller 144. The second region 54b is a region capable of attracting the developer to the developing roller 144, and is used to attract the developer. The first region 54a is an example of a first region and the second region 54b is an example of a second region.

Since the first area 54a and the second area 54B different from each other in relation to the flow of the developer are formed in the developer attracting area 50, an attracting area or attracting width B (hereinafter referred to as an attracting width B) where the developer is attracted to the developing roller 144 is narrowed due to the magnetic force of the developing roller 144. The attraction width B refers to a length as viewed in the axial direction of the developing roller 144. The attraction width B is proportional to the amount of developer that can be attracted to the developing roller 144. Further, the attraction width B is proportional to the magnetic force acting on the developing roller 144. With the present exemplary embodiment, because the attraction width B is reduced, the amount of developer attracted to the developing roller 144 is reduced, and the magnetic force acting on the developing roller 144 is also reduced.

More specifically, in the present exemplary embodiment, the supply port 53 is arranged downstream of the restricting member 51. If it is assumed that the supply port 53 is arranged upstream of the restriction member 51, the attraction width B increases, the amount of the developer attracted onto the developing roller 144 increases, and it becomes difficult to reduce the curvature of the developing roller 144 or the stress applied to the developing roller 144. For example, in order to avoid such a situation, it is conceivable that the amount of the developer attracted may be reduced by placing the restriction member 51 close to the developing roller 144.

However, when the restricting member 51 is placed closer to the developing roller 144, if the upstream space of the layer regulating member 145 is narrowed, the regulated developer is everywhere to generate a stagnation area where the developer does not move, and as a result, image defects such as color dots may occur.

In the present exemplary embodiment, the attraction width B is reduced by shifting the flow of the developer closer to the layer regulating member 145 using the above-described structure. Therefore, without placing the restriction member 51 closer to the developing roller 144, the occurrence of image defects is suppressed while suppressing an increase in the amount of developer attracted to the developing roller 144.

Fig. 5 is a diagram corresponding to fig. 3, illustrating the flow of the developer removed from the developing roller 144.

As shown in fig. 5, the restricting member 51 is arranged such that the upstream end portion 51b is positioned closer to the layer regulating member 145 than the removal-side tangent V of the developing roller 144 extending in the up-down direction. The restriction member 51 is an example of a restriction unit, an example of a first member, and an example of a first region formation portion.

The restriction member 51 restricts the flow of the developer removed from the developing roller 144 to the developer attracting area 50. Therefore, the removed developer is suppressed from entering the space between the developing roller 144 and the restricting member 51. Therefore, the removal developer having a low toner concentration is prevented from being carried by the developing roller 144.

Fig. 6 is a view corresponding to fig. 5, showing the developing device 14 according to the modification.

The developing device 14 according to the modification shown in fig. 6 includes a guide member 55, the guide member 55 being located upstream of the regulating member 51 and guiding the removed developer to a conveying path formed by rotation of the third conveying member 149 (see fig. 2). The guide member 55 is an embodiment of a restriction unit and is an embodiment of a guide member, which is disposed such that its upper end is adjacent to the developing roller 144 and its lower end is adjacent to the second conveyance member 147, and the guide member 55 covers a space between the developing roller 144 and the second conveyance member 147. The guide member 55 prevents the developer removed from the developing roller 144 from moving toward the restriction member 51.

In the present modification, the guide member 55 guides the removed developer to a conveying path formed by the rotation of the third conveying member 149 (see fig. 2). However, the guide member 55 may guide the removed developer to a circulation path (see fig. 2) in which the developer circulates in the axial direction by the rotation of each of the first conveying member 146 and the second conveying member 147.

The guide member 55 and the restricting member 51 are different members. However, this is not restrictive. The guide member 55 may be integrally formed with the restriction member 51.

The foregoing description of the exemplary embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise disclosure. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.