JP2019184690A - Image formation apparatus and developing device - Google Patents

Abstract

Image quality is less likely to be reduced as compared with a case where there is no suppression means for suppressing movement of a developer from a conveyance section side to a developer holding body side or an arrangement section arranged in a development device main body. The present invention provides a developing device and an image forming apparatus capable of performing the above. A developing device includes: a developing roll; a first auger for conveying the developer separated from the developing roll while stirring the developer; and a first auger in a first stirring chamber. A second auger 240 disposed on the side of the developing roll 210, a third auger 260 for stirring the developer in the second stirring chamber 250 and transporting the developer toward the developing roll 210, and a second auger 240. And a suppressor 280 that suppresses the movement of the developer from the 230 side to the developing roll 210 side. [Selection] Figure 2

Description

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

  In Patent Document 1, a developer carrying body provided to face the electrostatic latent image holding body and a first auger that transports the developer along the axial direction of the developer carrying body. And a second auger that is provided substantially parallel to the first agitating chamber, communicates with the first agitating chamber at both ends, and conveys the developer in a direction opposite to the first auger. A developing device having a second agitating chamber, the second agitating chamber being provided almost immediately below the first agitating chamber, and above the second auger in the second agitating chamber, A developing device is described that includes a third auger that conveys developer in a direction opposite to the second auger.

JP-A-6-51634

  If the developer separated from the developer holding member is reattached to the developer holding member with insufficient stirring, the toner concentration in the developer supplied from the developer holding member to the image holding member may become unstable. For example, there is a possibility that the quality of the formed image may be deteriorated, such as density spots.

  The present invention is less susceptible to image quality degradation than a case where there is no restraining means for suppressing the movement of the developer from the conveyance unit side to the developer holding member side or an arrangement unit arranged in the developing device main body. An object of the present invention is to provide a developing device and an image forming apparatus that can perform the above operation.

The present invention according to claim 1
A developer holder for holding a developer to be supplied to the image carrier;
A first transport unit that transports the developer separated from the developer holder while stirring in the first stirring chamber;
A second transport unit disposed closer to the developer holding body than the first transport unit in the first stirring chamber;
A third transport unit that stirs the developer in a second stirrer chamber adjacent to the first stirrer chamber and transports the developer toward the developer holder;
Suppressing means for suppressing the movement of the developer from the second conveying unit side to the developer holding body side;
Is a developing device.

The present invention according to claim 2
A developer holder for holding a developer to be supplied to the image carrier;
A first transport unit that transports the developer separated from the developer holder while stirring in the first stirring chamber;
A second transport unit disposed closer to the developer holding body than the first transport unit in the stirring chamber;
A third transport unit that stirs the developer in a second stirrer chamber adjacent to the first stirrer chamber and transports the developer toward the developer holder;
An arrangement portion arranged in the developing device main body so as to narrow an opening facing the developer holding body in the first stirring chamber;
Is a developing device.

The present invention according to claim 3 provides:
The developer holder is
An adsorption position for adsorbing the developer conveyed by the third conveyance unit;
A separation position for separating the adsorbed developer;
Have
The developing device according to claim 2, wherein the arrangement portion extends from the suction position side to the separation position side.

The present invention according to claim 4 provides:
The developer holder is
An adsorption position for adsorbing the developer conveyed by the third conveyance unit;
A separation position for separating the adsorbed developer;
Have
4. The developing device according to claim 2, wherein the arrangement portion has a shape that closes the suction position side of the opening while releasing the separation position side of the opening. 5.

  According to a fifth aspect of the present invention, in the arrangement unit, the end on the side of the separation position is a horizontal plane that passes through the rotation center of the second transport unit, and a vertical that passes through the rotation center of the second transport unit. 5. The developing device according to claim 2, wherein the developing device is disposed in a space surrounded by a plane, a horizontal plane passing through the rotation center of the developer holding body, and a vertical plane passing through the rotation center of the developer holding body. is there.

  According to a sixth aspect of the present invention, in the partition portion, the second transport unit is located on a side closer to the separation position than the surface passing through the rotation center of the second transport unit and the suction position. 6. The developing device according to claim 2, wherein the developing device is disposed at a position close to a plane passing through the rotation center and the rotation center of the developer holder.

  According to a seventh aspect of the present invention, in the longitudinal direction of the second transport unit, the arrangement portion is provided on one end side where the height of the developer is higher than the other end portion. The developing device according to any one of the above.

The present invention according to claim 8 provides:
A passage port through which a developer that moves so as to be pushed up from the first conveyance unit side to the third conveyance unit side is provided on one end side in the longitudinal direction of the second conveyance unit. And
The developing device according to any one of claims 2 to 6, wherein the arrangement portion is provided on the one end portion side in the longitudinal direction of the second transport portion.

The present invention according to claim 9 provides:
An image carrier for holding an image;
A developer holder for holding a developer to be supplied to the image carrier;
A first transport unit that transports the developer separated from the developer holder while stirring in the first stirring chamber;
A second transport unit disposed closer to the developer holding body than the first transport unit in the first stirring chamber;
A third transport unit that stirs the developer in a second stirrer chamber adjacent to the first stirrer chamber and transports the developer toward the developer holder;
Suppressing means for suppressing the movement of the developer from the second conveying unit side to the developer holding body side;
An image forming apparatus having

  According to the first aspect of the present invention, it is possible to make it difficult to cause a reduction in image quality as compared with a case where there is no suppressing means for suppressing the movement of the developer from the conveyance unit side to the developer holding body side. A developing device can be provided.

  According to the second aspect of the present invention, as compared with the case where the arrangement portion that narrows the opening of the stirring chamber is not provided, the reattachment of the developer separated from the developer holding body to the developer holding body is suppressed. be able to.

  According to the third aspect of the present invention, the repositioning of the developer separated from the developer holding body to the developer holding body is suppressed as compared with the case where the arrangement portion extends in a direction different from the separated position side. can do.

  According to the fourth aspect of the present invention, it is possible to suppress the reattachment of the developer separated from the developer holding body to the developer holding body as compared with the technique in which the suction position side of the opening is released. .

  According to the fifth aspect of the present invention, the end of the disposition portion on the separated position side is a horizontal plane that passes through the center of rotation of the second transport unit, a vertical plane that passes through the center of rotation of the second transport unit, and the developer Compared to the case where the developer holding body is separated from the space surrounded by the horizontal plane passing through the rotation center of the holding body and the vertical plane passing through the rotation center of the developer holding body, the developer developer separated from the developer holding body Reattachment to the holding body can be suppressed.

  According to this invention which concerns on Claim 6, the rotation part of a 2nd conveyance part is rather than the surface where the edge part by the side of a separation position of an arrangement | positioning part passes a 2nd conveyance part, a rotation center, and the said adsorption position. And re-deposition of the developer separated from the developer holding body to the developer holding body as compared with the case where the developer holding body is not disposed at a position close to the surface passing through the rotation center of the developer holding body. Can do.

  According to the seventh aspect of the present invention, in the longitudinal direction of the second transport unit, the height of the developer in the stirring chamber is higher than that of the other end portion, compared with the case where no arrangement portion is provided on the one end side. Thus, it is possible to provide a developing device capable of making it difficult for image quality to deteriorate.

  According to the eighth aspect of the present invention, in the longitudinal direction of the second transport unit, as compared with the case where the arrangement unit is not provided on the side of the passage port through which the developer moving so as to be pushed up passes, It is possible to provide a developing device that can make it difficult for image quality to deteriorate.

  According to the ninth aspect of the present invention, it is possible to make it difficult for image quality to be deteriorated as compared with the case where there is no suppression means for suppressing the movement of the developer from the conveying section side to the developer holding body side. An image forming apparatus can be provided.

1 is a diagram illustrating a schematic configuration of an image forming apparatus used in an embodiment of the present invention. FIG. 2 is a diagram illustrating a developing device included in the image forming apparatus illustrated in FIG. 1. FIG. 3 is a diagram illustrating movement of a developer in the developing device illustrated in FIG. 2. It is a figure explaining the suppression means which the developing device shown in FIG. 2 has. It is a 1st figure explaining arrangement | positioning of the partition part which the suppression means shown in FIG. 4 has. It is a 2nd figure explaining arrangement | positioning of the partition part shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating an example of an image forming apparatus 10 used in an embodiment of the present invention.

  As shown in FIG. 1, the image forming apparatus 10 includes an image forming apparatus main body 12, and an image forming unit 100 that forms an image in the image forming apparatus main body 12, a supply device 300, and a conveyance path 400 are arranged. Has been.

  The image forming unit 100 is an example of an image holding body that holds an image, and is charged by the photosensitive drum 102 that rotates in the direction of arrow a, the charging device 104 that charges the photosensitive drum 102, and the charging device 104. For example, a latent image forming apparatus 106 that forms a latent image by irradiating light onto the surface of the photosensitive drum 102, and a latent image formed by the latent image forming apparatus 106 is developed using a two-component developer, and a toner image. And a developing device 200. Details of the developing device 200 will be described later.

  The image forming unit 100 transfers, for example, a toner image developed by the developing device 200 to a recording medium such as paper, and fixing for fixing the toner image transferred to the recording medium by the transfer device 110 to the recording medium. And a device 130.

  The transfer device 110 is endless, and is rotatably suspended, for example, on three support rolls 114, and includes a transport member 112 that transports a recording medium by rotating in the direction of arrow b, and a transport member 112. A transfer roll 116 to which a transfer bias is applied, which is in contact with the surface opposite to the surface on which the photosensitive drum 102 is in contact.

  The fixing device 130 includes a heating roll 134 having a heat source 132 and a pressure roll 136 that presses the recording medium against the heating roll 134, and fixes the toner image on the recording medium using heat and pressure.

  The image forming unit 100 further includes a cleaning device 108. The cleaning device 108 cleans the surface of the photosensitive drum 102 after the toner image is transferred onto the recording medium by the transfer device 110.

  The supply device 300 is a device that supplies a recording medium to the image forming unit 100. The storage unit 302 stores the stacked recording media, and the recording medium stored in the storage unit 302 faces the image forming unit 100. And a delivery roll 304 for feeding out.

  The conveyance path 400 conveys the recording medium from the supply device 300 to the image forming unit 100, and further conveys the recording medium on which the image is formed by the image forming unit 100 toward the outside of the image forming apparatus main body 12. . Further, in order from the upstream side in the conveyance direction of the recording medium along the conveyance path 400, the above-described delivery roll 304, the conveyance roll 410 that conveys the recording medium, the registration roll 420, the above-described transfer device 110, and the above-mentioned description. The fixing device 130 is disposed.

  The registration roll 420 temporarily stops the movement of the leading end of the recording medium, and resumes the movement of the leading end of the recording medium so as to coincide with the timing at which the image forming unit 100 forms an image.

  In the image forming apparatus 10 configured as described above, the image forming unit 100 forms a toner image on the recording medium supplied by the supply apparatus 300, and the recording medium on which the toner image is formed is the image forming apparatus main body 12. It is discharged outside.

  FIG. 2 shows the developing device 200. The developing device 200 is a device that develops a latent image using a developer in which, for example, a nonmagnetic toner that is negatively charged and a magnetic carrier that is positively charged are mixed, for example, as shown in FIG. The developing device main body 202 is provided, and the developing roll 210 is disposed in the developing device main body 202.

  The developing roll 210 has, for example, a cylindrical magnet member 212 and a cylindrical sleeve, for example, which covers the magnet member 212 and rotates in the direction of arrow c while being supported by the magnet member 212. Here, the developing sleeve 214 is an example of a developer holding body that holds the developer supplied to the image holding body (photosensitive drum 102).

  The magnet member 212 has, for example, five magnetic poles. More specifically, the magnet member 212 includes an attracting magnetic pole N1, a conveying magnetic pole S1, a conveying magnetic pole N2, a developing magnetic pole S2, and a separating magnetic pole N3.

  The attracting magnetic pole N1 is used for attracting the developer conveyed to the developing roll 210 side by a third auger 260 described later to the surface of the developing sleeve 214. Here, the developing sleeve 214 adsorbs the developer at a position facing the attracting magnetic pole N1 and in the vicinity of the position facing the attracting magnetic pole N1. For this reason, hereinafter, the position of the developing sleeve 214 facing the suction magnetic pole N1 is referred to as a suction position P1.

  The conveying magnetic pole S1 is disposed downstream of the attracting magnetic pole N1 in the rotation direction of the developing sleeve 214, and maintains the adsorption of the developer to the surface of the developing sleeve 214, thereby rotating the developing sleeve 214. Along with this, it is used to transport the developer.

  The transport magnetic pole N2 is disposed downstream of the transport magnetic pole S1 in the rotation direction of the developing sleeve 214, and maintains the adsorption of the developer to the surface of the developing sleeve 214 in the same manner as the transport magnetic pole S1. Therefore, it is used for transporting the developer as the developing sleeve 214 rotates.

  The developing magnetic pole S2 is disposed on the downstream side of the conveying magnetic pole N2 in the rotation direction of the developing sleeve 214, and is disposed so as to face the moving region where the toner moves from the surface of the developing sleeve 214 to the photosensitive drum 102. In addition, it is used to form developer spikes in the vicinity of the photosensitive drum 102 and develop the latent image formed on the surface of the photosensitive drum 102 with toner.

  The separation magnetic pole N <b> 3 is disposed downstream of the development magnetic pole S <b> 2 in the rotation direction of the development sleeve 214 and is used to separate the developer from the surface of the development sleeve 214. Here, from the developing sleeve 214, the developer is separated from the position facing the separating magnetic pole N3 and the vicinity of the position facing the separating magnetic pole N3. For this reason, hereinafter, a position facing the separation magnetic pole N3 of the developing sleeve 214 is referred to as a separation position P2.

  A first stirring chamber 220 is provided in the developing device main body 202. A first auger 230 is disposed in the first stirring chamber 220. The first auger 230 is an example of a first transport unit. The first auger 230 is a developer in which toner is used for development, and conveys the developer separated from the developing sleeve 214 at the separation position P <b> 2 while stirring in the first stirring chamber 220.

  More specifically, the first auger 230 has a spiral blade portion 232, and rotates in the direction of arrow d shown in FIG. The developer is transported from the front side of the paper surface to the back side of the paper surface.

  The developing device 200 further includes a second auger 240. The second auger 240 is an example of a second transport unit, and is disposed closer to the developing roll 210 than the first auger 230 in the first stirring chamber 220. The second auger 240 faces the first auger 230 and conveys the developer in the opposite direction to the first auger 230. That is, the second auger 240 has a blade portion 242, rotates in the direction of arrow e shown in FIG. 2, and conveys the developer from the back side to the front side of the paper so as to be pushed out by the blade portion 242.

  A second stirring chamber 250 is further provided in the developing device main body 202. The second transfer chamber is located above the first stirring chamber 220 in the direction of gravity, communicates with the first stirring chamber 220, and the developer stirred in the first stirring chamber 220 is in the second stirring chamber 220. It is transported to the stirring chamber. Details of the second stirring chamber 250 will be described later.

  The developing device 200 further includes a third auger 260. The third auger 260 is an example of a third transport unit, and is disposed in the second stirring chamber 250, has a spiral blade portion 262, rotates in the direction of arrow f, and the blade portion. The developer is conveyed while agitating the developer so as to be pushed out by H.262. More specifically, the third auger 260 moves to the developing roll 210 side (left side in FIG. 2) while conveying the developer from the back side to the front side in the second stirring chamber 250. And move the developer.

  Then, the third auger 260 moves the developer toward the developing roll 210, whereby the developer stirred in the first stirring chamber 220 and further the developer stirred in the second stirring chamber 250 is moved. Then, the agitated developer supplied to the suction position P1 of the developing sleeve 214 is sucked to the developing sleeve 214 at the suction position P1.

  Further, in the developing device 200, the first stirring chamber 220 and the second stirring chamber 250 are one end portion in the longitudinal direction of the first auger 230 and the third auger 260 in FIG. It communicates with the side. More specifically, a through-hole 204 (see FIG. 3) is formed in the developing device main body 202 so that the developer can move from the second stirring chamber 250 to the first stirring chamber 220. Yes. Then, the developer moves from the second stirring chamber 250 to the first stirring chamber 220 so as to pass through the through hole 204 and drop.

  In the developing device 200, the first stirring chamber 220 and the second stirring chamber 250 are the other side in the longitudinal direction of the first auger 230 and the third auger 260 in FIG. It communicates with the side. More specifically, a through-hole 206 (see FIG. 3) is formed in the developing device main body 202 so that the developer can move from the first stirring chamber 220 to the second stirring chamber 250. Yes. Then, the first auger 230 allows the developer to pass through the through hole 206 and pushes the developer from the first stirring chamber 220 to the second stirring chamber 250 so that the developer is supplied to the first stirring chamber. Move from 220 to the second agitation chamber 250. Here, the through hole 206 is an example of a passage port through which the developer passes.

  As described above, in the developing device 200, the developer is moved so as to be pushed up from the first stirring chamber 220 to the second stirring chamber 250. The developer tends to stay in the second stirring chamber 250, and the height of the developer in the second stirring chamber 250 tends to be higher on the through hole 206 side and lower on the through hole 204 side. Then, the difference in the height of the developer in the developing device main body 202 may cause deterioration in the image quality of the image formed by the image forming apparatus 10 such as uneven density of the image. For this reason, in the image forming apparatus 10, the difference in the height of the developer in the developing device main body 202 is reduced by using the second auger 240.

  That is, in the developing device 200, the second auger 240 transports the developer from the through hole 206 side to the through hole 204 side, so that the developer stays in the vicinity of the through hole 206 in the developing device main body 202. And the difference in the height of the developer in the developing device main body 202 is alleviated.

  On the other hand, the second auger 240 is disposed closer to the developing roll 210 than the first auger 230 in the first stirring chamber 220, and is positioned at a position between the developing roll 210 and the first auger 230. Is arranged. For this reason, there is a possibility that the movement of the developer separated from the developing roller 210 at the separation position P2 toward the first auger 230 may be hindered by the second auger 240, and development that should originally proceed toward the first auger 230. The developer moves backward from the second auger 240 side to the developing roll 210 side, and the developer moved to the developing roll 210 side so as to go backward is returned to the developing sleeve 214 at the suction position P1. There is a risk of adhesion.

  In such a case, the developer not stirred by the first auger 230 and the third auger 260 is adsorbed by the developing sleeve 214 and used for development. For this reason, there is a possibility that the image quality may be deteriorated, for example, the density of the formed image may be reduced or the density of the formed image may be uneven.

  For this reason, the developing device 200 includes a suppressing unit 280, which suppresses the movement of the developer from the second auger 240 side to the developing roll 210 side, and stirs the developer separated from the developing roll 210. Re-adhering to the developing roll 210 while being insufficient is suppressed. Details of the suppression means 280 will be described later.

  FIG. 3 is a schematic diagram for explaining the movement of the developer in the developing device 200. 3, the right side corresponds to the back side of the paper in FIG. 2, and the left side corresponds to the front side of the paper in FIG. Also, the arrows in FIG. 3 indicate the flow (movement) of the developer in the developing device main body 202.

  As shown in FIG. 3, the developer separated from the developing roll 210 is conveyed to the right side in FIG. 3 by the first auger 230 in the first stirring chamber 220. Then, the developer conveyed to the right side in FIG. 3 by the first auger 230 moves to the second stirring chamber 250 so as to pass through the through hole 206. At this time, as described above, the developer tends to stay in the vicinity of the through hole 206, and the height of the developer in the developing device main body 202 may be higher on the through hole 206 side and lower on the through hole 204 side.

  Further, in the developing device main body 202, the second auger 240 transports the developer from the through hole 206 side to the through hole 204 side, thereby suppressing the retention of the developer in the vicinity of the through hole 206. The difference in the height of the developer when the through-hole 206 side is high and the through-hole 204 side is low is suppressed.

  The developer that has passed through the through hole 206 and has reached the second stirring chamber 250 is conveyed to the left side in FIG. 3 by the third auger 260, and a part thereof is adsorbed to the developing sleeve 214 at the adsorption position P1. Is done.

  FIG. 4 is a diagram for explaining the configuration of the suppression means 280. As shown in FIG. 4, the suppression means 280 has an arrangement part 282. The arrangement portion 282 is arranged in the developing device main body 202 so as to narrow the opening 222 facing the developing roll 210 of the first stirring chamber 220.

  The arrangement portion 282 has one end fixed to the inner wall of the first stirring chamber 220, and the other end extends from the suction position P1 side of the developing roll 210 to the separation position P2 side of the developing roll 210. Yes. In addition, the placement portion 282 has a shape that closes the suction position P1 side of the opening 222 while leaving the separation position P2 side of the opening 222 open.

  FIG. 5 is a first diagram illustrating the arrangement of the arrangement unit 282. As shown in FIG. 5, in the arrangement portion 282, the end portion 282 a on the side of the separation position P <b> 2 passes through the horizontal plane S <b> 11 that passes through the rotation center O <b> 1 of the second auger 240 and the rotation center O <b> 1 of the second auger 240. It is disposed so as to be located in a space surrounded by the vertical plane S12, a horizontal plane S13 passing through the rotation center O2 of the developing sleeve 214, and a vertical plane S14 passing through the rotation center O2 of the developing sleeve 214.

  FIG. 6 is a second view for explaining the arrangement of the arrangement portion 282. As shown in FIG. 6, the arrangement portion 282 has an end 282a on the side of the separation position P2 of the developing sleeve 214, and the second auger 240. Is positioned closer to the plane S16 passing through the rotation center O1 of the second auger 240 and the rotation center O2 of the developing sleeve 214 than the plane S15 passing through the rotation center O1 of the toner and the suction position P1 of the developing sleeve 214. It is arranged to be in the state.

  Further, the disposition portion 282 may extend over the entire area of the second auger 240 in the developing device main body 202, and the height of the developer is the other end in the longitudinal direction of the second auger 240. You may make it provide only in the one end part side higher than a part. That is, the disposing portion 282 is provided only on the through-hole 206 (see FIG. 3) side in the developing device main body 202, and is not provided on the through-hole 204 (see FIG. 3) side in the developing device main body 202. May be.

  In the developing device 200 configured as described above, the disposing portion 282 of the suppressing unit 280 suppresses the movement of the developer from the second auger 240 side to the developing roll 210 side, and the stirring is performed at the separation position P2. Is prevented from reattaching to the developing sleeve 214 at the developer adsorption position P1.

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus 102 ... Photosensitive drum 200 ... Developing device 210 ... Developing roll 214 ... Developing sleeve 220 ... First stirring chamber 222 ... Opening 230 ... First auger 240 ... second auger 280 ... suppression means 282 ... arrangement portion 282a ... end O1 ... rotation center O2 ... rotation center P1 ... adsorption position P2. ..Separation position S11 ... Horizontal plane S12 ... Vertical plane S13 ... Horizontal plane S14 ... Vertical plane S15 ... Plane S16 ... Plane

Claims (9)

A developer holder for holding a developer to be supplied to the image carrier;
A first transport unit that transports the developer separated from the developer holder while stirring in the first stirring chamber;
A second transport unit disposed closer to the developer holding body than the first transport unit in the first stirring chamber;
A third transport unit that stirs the developer in a second stirrer chamber adjacent to the first stirrer chamber and transports the developer toward the developer holder;
Suppressing means for suppressing the movement of the developer from the second conveying unit side to the developer holding body side;
A developing device. A developer holder for holding a developer to be supplied to the image carrier;
A first transport unit that transports the developer separated from the developer holder while stirring in the first stirring chamber;
A second transport unit disposed closer to the developer holding body than the first transport unit in the stirring chamber;
A third transport unit that stirs the developer in a second stirrer chamber adjacent to the first stirrer chamber and transports the developer toward the developer holder;
An arrangement portion arranged in the developing device main body so as to narrow an opening facing the developer holding body in the first stirring chamber;
A developing device. The developer holder is
An adsorption position for adsorbing the developer conveyed by the third conveyance unit;
A separation position for separating the adsorbed developer;
Have
The developing device according to claim 2, wherein the arrangement portion extends from the suction position side to the separation position side. The developer holder is
An adsorption position for adsorbing the developer conveyed by the third conveyance unit;
A separation position for separating the adsorbed developer;
Have
The developing device according to claim 2, wherein the arrangement portion has a shape that closes the suction position side of the opening while the separation position side of the opening is released.   The arrangement unit includes a horizontal plane in which an end on the side of the separation position passes through the rotation center of the second conveyance unit, a vertical plane that passes through the rotation center of the second conveyance unit, and rotation of the developer holder. 5. The developing device according to claim 2, wherein the developing device is disposed in a space surrounded by a horizontal plane passing through the center and a vertical plane passing through the rotation center of the developer holder.   The partition portion includes a rotation center of the second conveyance unit and the developer holding member, rather than a surface where the end on the separation position side passes through the rotation center of the second conveyance unit and the suction position. The developing device according to any one of claims 2 to 5, wherein the developing device is disposed at a position close to a surface passing through the rotation center.   The developing device according to claim 2, wherein the arrangement portion is provided on one end portion side in which a height of the developer is higher than that of the other end portion in the longitudinal direction of the second transport portion. A passage port through which a developer that moves so as to be pushed up from the first conveyance unit side to the third conveyance unit side is provided on one end side in the longitudinal direction of the second conveyance unit. And
The developing device according to any one of claims 2 to 6, wherein the arrangement portion is provided on the one end portion side in the longitudinal direction of the second conveyance portion. An image carrier for holding an image;
A developer holder for holding a developer to be supplied to the image carrier;
A first transport unit that transports the developer separated from the developer holder while stirring in the first stirring chamber;
A second transport unit disposed closer to the developer holding body than the first transport unit in the first stirring chamber;
A third transport unit that stirs the developer in a second stirrer chamber adjacent to the first stirrer chamber and transports the developer toward the developer holder;
Suppressing means for suppressing the movement of the developer from the second conveying unit side to the developer holding body side;
An image forming apparatus.

Images