JP6011397B2 - Developing device and image forming apparatus - Google Patents

Description

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

As a technique for regulating the thickness of a developer layer formed on the surface of a developing member in a developing device of an image forming apparatus, Patent Document 1 below is known.
Japanese Patent Application Laid-Open No. 2011-17857 as Patent Document 1 discloses an upstream side of the agent regulating member (35) in the developing device that regulates the amount of developer on the surface of the developing sleeve (34a) by the agent regulating member (35). Then, the shielding wall (130) is arranged at a position where the developer is supplied to the developing sleeve (34a), and the developer is supplied to the developing sleeve (34a) from the gap between the shielding wall (130) and the barrier (13). Thus, a technique for stabilizing the supply amount of the developer is described.

JP 2011-17857 A (“0021” to “0022”, “0041” to “0044”, FIGS. 1 and 6)

  An object of the present invention is to prevent the developer regulated by the regulating member from staying on the upstream side.

In order to solve the technical problem, the developing device of the invention according to claim 1 comprises:
A container for containing a developer;
A developing member disposed opposite to the image holding member, the rotating member holding the developer for developing the latent image on the surface of the image holding member into a visible image, and the rotating member; A magnetic member disposed inside and having a plurality of magnetic poles for generating magnetic force for attracting the developer in the container to the surface of the rotating body; and
A developer that is disposed on the upstream side of the position facing the image holding member with respect to the rotation direction of the rotating member, is disposed in the vicinity of the surface of the rotating member, and is held on the surface of the rotating member. A regulating member that regulates the amount of
A regulating magnetic pole arranged corresponding to the regulating member, and an adsorption arranged upstream of the regulating magnetic pole with respect to the rotation direction of the rotating body and adsorbing developer on the surface of the rotating body The magnetic member having at least a magnetic pole for,
The developer regulated by the regulating member, a guide portion for guiding toward the container, the lower end portion of the guide portion, the magnetic force between the magnetic pole and the magnetic pole for adsorption for the regulation The guide unit disposed on an extension line of a virtual line segment connecting a minimal position and the rotation center of the rotating body;
The regulating magnetic pole disposed above in the direction of gravity with respect to the rotation center of the rotating body;
The magnetic pole for adsorption disposed below the rotation center of the rotating body in the direction of gravity and adjacent to the magnetic pole for regulation;
A lower end portion of the guide portion disposed below the rotation center of the rotating body in the gravitational direction and above the attracting magnetic pole in the gravitational direction;
It is provided with.

The invention according to claim 2 is the developing device according to claim 1,
A second developing member disposed on the upstream side of the developing member with respect to the rotation direction of the image holding member and facing the image holding member; A second rotating body that rotates while holding the developer to be developed into a visual image, and a magnetic force that is disposed inside the second rotating body and that attracts the developer to the surface of the second rotating body A second magnet member having a plurality of magnetic poles for generating a magnetic field, and developing from the rotating body to the second rotating body in a region where the rotating body of the developing member and the second rotating body face each other. The second developing member on which the magnetic pole for moving the agent is disposed;
It is provided with.

In order to solve the technical problem, an image forming apparatus according to claim 3 is provided.
An image carrier,
A latent image forming apparatus for forming a latent image on the image carrier;
The developing device according to claim 1 or 2 , wherein the latent image of the image carrier is developed into a visible image;
A transfer device for transferring a visible image of the image carrier to a medium;
A fixing device for fixing the visible image transferred to the medium;
It is provided with.

According to the first and third aspects of the present invention, the developer regulated by the regulating member stays on the upstream side as compared with the configuration in which the end of the guide portion is not arranged corresponding to the position where the magnetic force is minimal. This can be suppressed. Further, according to the first and third aspects of the present invention, it is possible to suppress the developer not adsorbed on the surface of the rotating body from entering the space surrounded by the regulating member, the rotating body, and the guide portion.
According to the second aspect of the present invention, it is possible to prevent the developer regulated by the regulating member from staying upstream while delivering the developer to the second developing member .

FIG. 1 is an explanatory diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an explanatory cross-sectional view of a main part of the developing device according to the first embodiment. FIG. 3 is an explanatory diagram of the developing device of Example 1, and is a cross-sectional view taken along the line III-III of FIG. FIG. 4 is an explanatory view of a main part in the vicinity of the trimmer of the first developing roll of Example 1. FIG. 5 is an explanatory view of the vicinity of a trimmer in a conventional developing roll. 6 is an explanatory diagram of the magnetic profile and the magnetic force. FIG. 6A is a graph in which the horizontal axis indicates the phase and the vertical axis indicates the magnetic flux density in the conventional configuration shown in FIG. 5, and FIG. 6C is a graph in which the horizontal axis represents the phase and the vertical axis represents the magnetic force, and FIG. 6C is a graph in which the horizontal axis represents the phase and the vertical axis represents the magnetic flux density in the first embodiment. 6D is a graph in which the horizontal axis indicates the magnetic force in Example 1 and the vertical axis indicates the magnetic force. FIG. 7 is an explanatory diagram of the magnetic field in the region where the developer is transferred, FIG. 7A is an explanatory diagram of the magnetic field in the conventional configuration, and FIG. 7B is an explanatory diagram of the magnetic field in the configuration of the first embodiment.

Next, examples as specific examples of embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as front, rear, right, left, upper, lower, or front, rear, right, left, upper, and lower, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.
In the following description using the drawings, illustrations other than members necessary for the description are omitted as appropriate for easy understanding.

FIG. 1 is an explanatory diagram of an image forming apparatus according to a first embodiment of the present invention.
In FIG. 1, a copier U as an example of an image forming apparatus according to the first exemplary embodiment is an example of a recording unit, and includes a printer unit U1 as an example of an image recording apparatus. A scanner unit U2 as an example of a reading unit and an example of an image reading device is supported on the upper portion of the printer unit U1. An auto feeder U3 as an example of a document transport device is supported on the upper portion of the scanner unit U2. The scanner unit U2 of the first embodiment supports a user interface U0 as an example of an input unit. The user interface U0 can be operated by the operator by inputting the user interface U0.

  A document tray TG1 as an example of a medium container is disposed on the upper part of the auto feeder U3. A plurality of documents Gi to be copied can be stacked and stored in the document tray TG1. A document discharge tray TG2 as an example of a document discharge unit is formed below the document tray TG1. A document transport roll U3b is disposed along the document transport path U3a between the document tray TG1 and the document discharge tray TG.

A platen glass PG as an example of a transparent document table is disposed on the upper surface of the scanner unit U2. In the scanner unit U2 of the first embodiment, a reading optical system A is disposed below the platen glass PG. The optical system A for reading in Example 1 is supported so as to be movable in the left-right direction along the lower surface of the platen glass PG. The reading optical system A is normally stopped at the initial position shown in FIG.
On the left side of the optical system A for reading, an imaging element CCD as an example of an imaging member is disposed. An image processing unit GS is electrically connected to the image sensor CCD.
The image processing unit GS is electrically connected to the writing circuit DL of the printer unit U1. The writing circuit DL is electrically connected to an exposure machine ROS as an example of a latent image forming apparatus.

A photosensitive drum PR, which is an example of an image carrier, is disposed below the exposure machine ROS. The photosensitive drum PR rotates in the direction of the arrow Ya.
On the photosensitive drum PR, a charging roll CR, which is an example of a charger, is disposed opposite to the charging area Q0. A charging voltage is applied from the power supply circuit E to the charging roll CR. The power supply circuit E is controlled by a controller C as an example of a control unit. The controller C performs various controls by transmitting and receiving signals to and from the image processing unit GS and the writing circuit DL.
In the writing area Q1 set on the downstream side of the charging area Q0 with respect to the rotation direction of the photosensitive drum PR, a laser beam L as an example of writing light from the exposure device ROS is applied to the surface of the photosensitive drum PR. Is irradiated.
In the developing area Q2 set on the downstream side of the writing area Q1 with respect to the rotation direction of the photosensitive drum PR, the developing device G is disposed to face the surface of the photosensitive drum PR.
A transfer area Q3 is set on the downstream side of the development area Q2 with respect to the rotation direction of the photosensitive drum PR.

Under the printer unit U1, paper feed trays TR1 to TR4 as examples of a medium container are detachably supported. Sheets T as an example of a medium are accommodated in the sheet feed trays TR1 to TR4.
A pickup roll Rp as an example of a medium take-out member is disposed on the upper left side of the paper feed trays TR1 to TR4. On the left side of the pickup roll Rp, a separation roll Rs as an example of a spreading member is arranged.
On the left side of each of the paper feed trays TR1 to TR4, a medium transport path SH1 extending upward is formed. A plurality of transport rolls Ra as an example of a medium transport member are arranged in the transport path SH1. In the conveyance path SH1, a registration roll Rr as an example of a feeding member is disposed on the downstream side in the conveyance direction of the sheet S and on the upstream side of the transfer region Q3.

In the transfer area Q3, a transfer unit TU, which is an example of a transfer device and an example of a medium transport device, is disposed below the photosensitive drum PR. The transfer unit TU includes an endless transfer belt TB as an example of a medium transport member.
The transfer belt TB is rotatably supported by a driving roll Rd as an example of a driving member and a driven roll Rf as an example of a driven member.
Inside the transfer belt TB, a transfer roll TR as an example of a transfer device is supported. The transfer roll TR is disposed to face the photosensitive drum PR with the transfer belt TB interposed therebetween. Therefore, the transfer region Q3 is constituted by the region where the transfer roll TR and the photosensitive drum PR face each other. A transfer voltage is applied from the power supply circuit E to the transfer roll TR.

A peeling claw SC as an example of a medium peeling member is disposed at the right end of the transfer belt TB. Below the peeling claw SC, a belt cleaner CLb as an example of a cleaner of the transfer device is disposed to face the surface of the transfer belt TB.
Note that a drum cleaner CLp, which is an example of an image carrier cleaner, is disposed on the downstream side of the transfer region Q3 with respect to the rotation direction of the photosensitive drum PR so as to face the surface of the photosensitive drum PR. Yes.

A fixing device F is disposed on the right side of the transfer unit TU. The fixing device F includes a heating roll Fh as an example of a rotating member for heating and a pressure roll Fp as an example of a rotating member for pressure.
To the right of the fixing device F, a discharge path SH2 extending upward is connected as an example of a medium transport path.
In the discharge path SH2, as an example of a medium transport member, a transport roll Rb and a discharge roll Rh capable of transporting the medium and rotating in the forward and reverse directions are arranged.
A paper discharge tray TRh as an example of a medium discharge unit is formed on the upper surface of the printer unit U1.

A reversing path SH3, which is an example of a medium transport path, is formed below the discharge path SH2. The reversing path SH3 according to the first embodiment branches from the discharge path SH2 and extends downward, and joins the transport path SH1 on the upstream side in the sheet transport direction from the registration roll Rr.
A gate MG as an example of a transfer direction switching member is disposed at a branch portion between the discharge path SH2 and the reversal path SH3. The gate MG of the first embodiment is formed of an elastically deformable thin film shape, so-called film. When the sheet S conveyed from the fixing device F passes through the gate MG, the gate MG is pushed by the sheet S and is elastically deformed so that the sheet S can pass through the discharge path SH2. When the sheet S is conveyed from the discharge path SH2 to the reversing path SH3, the gate MG is held in an elastically restored state, preventing the sheet S from entering the fixing device F, and the reversing path SH3. It arrange | positions so that the sheet | seat S may be guided to the side.

(Description of image forming operation)
The plurality of documents Gi stored in the document tray TG1 sequentially passes through the document reading position on the platen glass PG and is discharged to the document discharge tray TG2.
When the automatic feeder U3 is used to automatically convey and copy a document, each document that sequentially passes through the reading position on the platen glass PG with the reading optical system A stopped at the initial position. Gi is exposed.
When the operator places the document Gi on the platen glass PG by hand, the optical system A for reading moves in the left-right direction, and the document on the platen glass PG is scanned while being exposed.
The reflected light from the document Gi passes through the optical system A and is collected on the image sensor CCD. The image pickup device CCD converts the reflected light of the original collected on the image pickup surface into an electric signal.

The image processing unit GS converts the read signal input from the image sensor CCD into a digital image signal and outputs the digital image signal to the writing circuit DL of the printer unit U1. The writing circuit DL outputs a control signal corresponding to the input image writing signal to the exposure device ROS.
The surface of the photosensitive drum PR is charged by the charging roll CR in the charging region Q0. At the latent image writing position Q1, the laser beam L output from the exposure device ROS forms an electrostatic latent image on the surface of the photosensitive drum PR. In the developing area Q2, the developing device G develops the electrostatic latent image on the photosensitive drum PR passing through the developing area Q2 into a toner image as an example of a visible image. When the developer is consumed in the developing device G, the developer is replenished to the developing device G from a developer container (not shown) according to the consumption amount.

  The sheets S of the respective trays TR1 to TR4 are taken out by the pickup roll Rp at a preset sheet feeding time. The sheets S picked up by the pickup roll Rp are separated one by one by the separating roll Rs when picked up in a state where a plurality of sheets S are overlapped. The sheet S that has passed the separating roll Rs is conveyed to the registration roll Rr by a plurality of conveyance rolls Ra.

The sheet S conveyed to the registration roll Rr is transferred from the sheet guide SG1 before transfer as an example of a guide member before transfer to the transfer area according to the timing when the toner image on the surface of the photosensitive drum PR moves to the transfer area Q3. It is transported toward Q3.
The sheet S conveyed from the registration roll Rr is supported on the surface of the transfer belt TB and passes through the transfer region Q3. A toner image on the surface of the photosensitive drum PR is transferred to the sheet S passing through the transfer region Q3 by a transfer voltage applied to the transfer roll TR.
The surface of the photosensitive drum PR after passing through the transfer region Q3 is cleaned by removing residual toner by the drum cleaner CLp. The surface of the photosensitive drum PR after cleaning is recharged by the charging roll CR.

The sheet S to which the toner image is transferred is peeled from the transfer belt TB by the peeling claw SC. From the transfer belt TB from which the sheet S has been peeled off, deposits such as developer and paper dust attached to the surface of the transfer belt TB are removed by the belt cleaner CLb. When the sheet S peeled from the transfer belt TB passes through the contact area between the heating roll Fh and the pressure roll Fp, the toner image is heated and pressed to be fixed.
The recording sheet S on which the toner image is fixed passes through the gate MG while being elastically deformed, and is conveyed to the discharge path SH2. The sheet S discharged to the paper discharge tray TRh is transported by the transport roll Rb and discharged to the paper discharge tray TRh by the discharge roll Rh.

  When duplex printing is performed, the trailing edge of the sheet S on which one side has been recorded is conveyed downstream by the conveyance roll Rb and the discharge roll Rh until it passes through the gate MG. When the trailing edge of the sheet S passes through the gate MG, the transport roll Rb and the discharge roll Rh rotate in the reverse direction and are transported from the discharge path SH2 toward the reversal path SH3. That is, the sheet S is so-called switched back with the conveyance direction reversed. The switched sheet S is guided by the gate MG and conveyed through the reversing path SH3. The sheet S conveyed on the reversing path SH3 joins the conveying path SH1, and is conveyed to the registration roll Rr with the front and back sides reversed. Then, an image is printed on the second surface of the sheet S in the transfer region Q3.

(Description of developing device)
FIG. 2 is an explanatory cross-sectional view of a main part of the developing device according to the first embodiment.
FIG. 3 is an explanatory diagram of the developing device of Example 1, and is a cross-sectional view taken along the line III-III of FIG.
1 and 2, the developing device G of Example 1 includes a container 1. The container 1 contains a developer. In Example 1, as a developer, a developer including a carrier as an example of magnetic powder and a toner as an example of powder for development, a so-called two-component developer is configured.
The container 1 has a container body 1a extending in the front-rear direction. A cylindrical portion 1b extending forward is supported at the front end of the main body 1a of the container. Moreover, the cylinder part 1c extended backward is supported by the rear-end part of the main body 1a of a container.

An admix chamber 2 as an example of a first storage chamber is formed on the left side of the container main body 1a and the cylindrical portion 1b. The admix chamber 2 extends in the front-rear direction. On the upper surface of the front end portion of the admix chamber 2, a supply port 2a as an example of a supply unit is formed. The replenishing port 2a is configured so that the developer can be replenished from a developer replenishing device (not shown). On the right side of the admix chamber 2, a supply chamber 3 as an example of a second storage chamber is formed. The supply chamber 3 extends in the front-rear direction in parallel with the admix chamber 2. A partition wall 4 as an example of a partition portion is formed between the admix chamber 2 and the supply chamber 3. The partition wall 4 is formed to be shorter in the front-rear direction than the admix chamber 2 and the supply chamber 3. Therefore, the admix chamber 2 and the supply chamber 3 are connected by the first inflow portion 6 at the front end and the second inflow portion 7 at the rear end. Therefore, the container 1 according to the first embodiment is configured such that the developer can move between the admix chamber 2 and the supply chamber 3 through the inflow portions 6 and 7.
The admix chamber 2 and the supply chamber 3 constitute circulation chambers 2 and 3 as an example of a circulation section.

A discharge chamber 8 as an example of a developer discharge unit is connected to the rear of the supply chamber 3. A developer discharge port 8 a is formed at the rear end of the discharge chamber 8. The developer discharge port 8a is connected to a collection container (not shown).
Formed on the upper right side of the supply chamber 3 is a first developing chamber 11 as an example of a housing portion for a first developing member. A second developing chamber 12 is formed above the first developing chamber 11 as an example of a housing portion for the second developing member.
A storage chamber 13 as an example of a storage unit is formed above the admix chamber 2 and the supply chamber 3. The bottom of the storage chamber 13 of the first embodiment is connected to the upper portion of the supply chamber 3. Therefore, the developer in the storage chamber 13 is configured to be able to flow into the supply chamber 3.

In the admix chamber 2, an admix auger 16 as an example of a first transport member is disposed. The admix auger 16 according to the first embodiment includes a first rotating shaft 16a as an example of a first shaft portion. A first transport blade 16b as an example of a first transport unit is supported on the outer periphery of the first rotating shaft 16a. The first conveying blade 16b is formed in a spiral shape with respect to the axial direction.
In the supply chamber 3, a supply auger 17 as an example of a second transport member is disposed. The supply auger 17 according to the first embodiment includes a second rotating shaft 17a as an example of a second shaft portion. A second conveying blade 17b as an example of a second conveying unit is supported on the outer periphery of the second rotating shaft 17a. The second conveying blade 17b is formed in a spiral shape with respect to the axial direction. Note that the second rotating shaft 17 a of the first embodiment extends to the rear end of the discharge chamber 8. The second rotating shaft 17a supports a discharge blade 17c as an example of a discharge transport unit in a range corresponding to the discharge chamber 8.
Each of the augers 16 and 17 has a rotational direction and a spiral direction of the conveying blades 16b and 17b so as to convey the developer in opposite directions when rotating.

A paddle 18 as an example of a third transport member is supported in the storage chamber 13. The paddle 18 has a third rotating shaft 18a as an example of a third shaft portion. A third transport blade 18b as an example of a third transport unit is supported on the third rotating shaft 18a. The third conveying blade 18b according to the first embodiment is formed in a plate shape extending in the radial direction from the third rotating shaft 18a.
A first developing roll 21 as an example of a first developing member is supported in the first developing chamber 11. The first developing roll 21 has a first magnet roll 21a as an example of a magnet member. The first magnet roll 21 a is fixedly supported by the container 1. A first developing sleeve 21b as an example of a developer holding body is disposed on the outer periphery of the first magnet roll 21a. The first developing sleeve 21b is formed in a hollow cylindrical shape.
In the second developing chamber 12, a second developing roll 22 as an example of a second developing member is supported. The second developing roll 22 is configured in the same manner as the first developing roll 21, and includes a second magnet roll 22a as an example of a magnet member, and a second developing sleeve as an example of a developer holding body. 22b.

A first developing region Q2a is configured by a region where the first developing roll 21 and the photosensitive drum PR face each other. A second developing region Q2b is configured by a region where the second developing roll 22 and the photosensitive drum PR face each other. Therefore, in the first embodiment, the second development region Q2b is disposed on the upstream side of the first development region Q2a with respect to the rotation direction of the photosensitive drum PR. The first development area Q2a and the second development area Q2b constitute the development area Q2 of Example 1.
The first developing sleeve 21b according to the first exemplary embodiment rotates in the direction along the rotation direction of the photosensitive drum PR in the first developing region Q2a. Further, the second developing sleeve 22b according to the first embodiment rotates in the direction opposite to the rotation direction of the photosensitive drum PR in the second developing region Q2b. Therefore, in the first embodiment, the first developing sleeve 21b rotates in the “with” direction and the second developing sleeve 22b rotates in the “against” direction with respect to the photosensitive drum PR.

In FIG. 2, a trimmer 31 as an example of a layer-thickness regulating member is supported diagonally to the left of the first developing roll 21. The tip of the trimmer 31 is supported at a predetermined interval with respect to the first developing sleeve 21b.
The trimmer 31 is supported by a holder 32 as an example of a support member for a regulating member. The holder 32 of the first embodiment is formed in a so-called block shape extending in the front-rear direction. A guide surface 32 a extending toward the supply chamber 3 in the lower left direction is formed on the lower right surface of the holder 32.
A chute 33 as an example of a developer guide member is disposed on the left side of the second developing roll 22. The chute 33 according to the first exemplary embodiment is disposed such that the tip is close to the surface of the second developing sleeve 22b. A proximal end portion of the chute 33 extends to the storage chamber 13. Accordingly, the chute 33 guides the developer peeled from the second developing sleeve 22 b to the storage chamber 13.

(Description of magnetic pole)
FIG. 4 is an explanatory view of a main part in the vicinity of the trimmer of the first developing roll of Example 1.
In FIG. 2, the first magnet roll 21 a has a pickup magnetic pole N <b> 11 as an example of a magnetic pole for adsorption at a position corresponding to the supply auger 17.
In FIG. 4, the pickup magnetic pole N11 of the first embodiment is set at a position rotated by 153 ° along the rotation direction of the first developing sleeve 21b with respect to the preset reference position. In Example 1, the magnetic pole strength of the pickup magnetic pole N11 is set to 73 [mT]. In the first embodiment, the reference position 36 is set on a horizontal plane. As shown in FIG. 4, in Example 1, the pickup magnetic pole N <b> 11 is disposed below the rotation center 21 c of the first developing roll 21 in the gravity direction.

A trimming magnetic pole S11 as an example of a magnetic pole for regulating the layer thickness is arranged downstream of the pickup magnetic pole N11 with respect to the rotation direction of the first developing sleeve 21b. The trimming magnetic pole S11 is arranged corresponding to the trimmer 31. The trimming magnetic pole S11 is composed of a magnetic pole having a polarity opposite to that of the pickup magnetic pole N11.
The trimming magnetic pole S11 of the first embodiment is set at a position rotated 148.5 ° along the reverse rotation direction of the first developing sleeve 21b with respect to a preset reference position 36. The magnetic pole strength of the trimming magnetic pole S11 of the first embodiment is set to 77 [mT]. As shown in FIG. 4, in the first embodiment, the trimming magnetic pole S <b> 11 is disposed above the rotation center 21 c of the first developing roll 21 in the gravity direction.

  In the first embodiment, the holder 32 is placed on the extension line of the imaginary line segment 37 that connects the position where the magnetic force is minimized between the trimming magnetic pole S11 and the pickup magnetic pole N11 and the rotation center 21c of the first developing roll 21. The positions of the trimming magnetic pole S11 and the pickup magnetic pole N11 and the strength of the magnetic force are set so that the lower end portion 32b of the guide portion 32a is disposed. In the first embodiment, an intermediate position 37a between the trimming magnetic pole S11 and the pickup magnetic pole N11 that substantially coincides with the position where the magnetic force is minimized between the trimming magnetic pole S11 and the pickup magnetic pole N11 corresponds to the lower end 32b of the guide portion 32a. Are arranged. As shown in FIG. 4, in the first embodiment, the lower end portion 32 b of the guide portion 32 a is disposed below the rotation center 21 c of the first developing roll 21 in the gravity direction.

  In FIG. 2, a delivery magnetic pole N12 as an example of one counter magnetic pole is disposed downstream of the trimming magnetic pole S11 with respect to the rotation direction of the first developing sleeve 21b. The transfer magnetic pole N12 of the first embodiment is disposed corresponding to the closest position 41 of the developing sleeves 21b and 22b. The delivery magnetic pole N12 is composed of a magnetic pole having a polarity opposite to that of the trimming magnetic pole S11.

A first transport magnetic pole S12 is disposed downstream of the transfer magnetic pole N12 with respect to the rotation direction of the first developing sleeve 21b. The first transport magnetic pole S12 is composed of a magnetic pole having a polarity opposite to that of the delivery magnetic pole N12.
A first developing magnetic pole N13 is disposed downstream of the first conveying magnetic pole S12 with respect to the rotation direction of the first developing sleeve 21b. The first developing magnetic pole N13 is disposed corresponding to the first developing region Q2a. The first developing magnetic pole N13 is composed of a magnetic pole having a polarity opposite to that of the first conveying magnetic pole S12.

A second transport magnetic pole S13 is disposed on the downstream side of the first developing magnetic pole N13 with respect to the rotation direction of the first developing sleeve 21b. The second transport magnetic pole S13 is composed of a magnetic pole having a polarity opposite to that of the first developing magnetic pole N13.
On the downstream side of the second transport magnetic pole S13 with respect to the rotation direction of the first developing sleeve 21b,
A pick-off magnetic pole N14 as an example of the separation magnetic pole is disposed. The pick-off magnetic pole N14 is composed of a magnetic pole having the same polarity as that of the pickup magnetic pole N11 and having a polarity opposite to that of the second transport magnetic pole S13. Further, the pick-off magnetic pole N14 is arranged so that the position where the magnetic force becomes minimum between the pick-off magnetic pole N14 and the pickup magnetic pole N11 corresponds to the supply chamber 3.

  On the magnet roll 22 a of the second developing roll 22, receiving magnetic poles S <b> 21 and N <b> 21 as examples of the other counter magnetic pole are arranged corresponding to the closest position. The receiving magnetic poles S21 and N21 of the first embodiment are configured by a pair of magnetic poles having different polarities. In the first embodiment, the receiving magnetic poles S21 and N21 are arranged at positions symmetrical with respect to the rotation direction of the second developing sleeve 22b with respect to the closest position. Further, in the first embodiment, the first receiving magnetic pole S21 arranged on the upstream side with respect to the rotation direction of the second developing sleeve 22b is configured by a magnetic pole having a polarity opposite to that of the passing magnetic pole N12. Accordingly, the second receiving magnetic pole N21 arranged on the downstream side with respect to the rotation direction of the second developing sleeve 22b is configured by a magnetic pole having the same polarity as the delivery magnetic pole N12.

A second developing magnetic pole S22 is disposed on the downstream side of the second receiving magnetic pole N21 with respect to the rotation direction of the second developing sleeve 22b. The second developing magnetic pole S22 according to the first exemplary embodiment includes a magnetic pole having a polarity opposite to that of the second receiving magnetic pole N21. Therefore, a magnetic field for attracting the developer to the second developing sleeve 22b is generated between the second developing magnetic pole S22 and the second receiving magnetic pole N21 of the first embodiment.
Further, the second developing magnetic pole S22 of Example 1 is disposed at a position corresponding to the second developing region Q2b. In the first embodiment, the second developing roll 22 of the first embodiment is located at a position shifted to the upstream side in the rotation direction of the second developing sleeve 22b with respect to the closest position between the second developing roll 22 and the photosensitive drum PR. A developing magnetic pole S22 is arranged.

A third transport magnetic pole N22 is disposed downstream of the second development magnetic pole S22 with respect to the rotation direction of the second development sleeve 22b. The third transport magnetic pole N22 is composed of a magnetic pole having a polarity opposite to that of the second developing magnetic pole S22.
A fourth transport magnetic pole S23 is disposed on the downstream side of the third transport magnetic pole N22 with respect to the rotation direction of the second developing sleeve 22b. The fourth transport magnetic pole S23 is composed of a magnetic pole having a polarity opposite to that of the third transport magnetic pole N22.

A first pick-off magnetic pole N23 is disposed downstream of the fourth transport magnetic pole S23 with respect to the rotation direction of the second developing sleeve 22b. In addition, a second pick-off magnetic pole N24 is disposed on the downstream side of the first pick-off magnetic pole N23 with respect to the rotation direction of the second developing sleeve 22b. In the first embodiment, the pick-off magnetic poles N23 and N24 are composed of magnetic poles having the same polarity and opposite to the fourth transport magnetic pole S23.
In the first embodiment, the pickoff magnetic poles N23 and N24 are arranged so that the position where the magnetic force between the first pickoff magnetic pole N23 and the second pickoff magnetic pole N24 is minimized corresponds to the tip of the chute 33. Has been.

(Operation of Example 1)
In the copying machine U of the first embodiment having the above-described configuration, when the image forming operation is started, the developing rolls 21 and 22, the augers 16 and 17, and the paddle 18 of the developing device G start to rotate. As the augers 16 and 17 rotate, the developer contained in the admix chamber 2 and the supply chamber 3 is conveyed in the opposite directions while being agitated. The developer conveyed to the downstream portion of each chamber 2, 3 flows into the other chamber 2, 3 through the inflow portions 6, 7. Therefore, the developer circulates between the admix chamber 2 and the supply chamber 3. Part of the developer flowing from the admix chamber 2 into the supply chamber 3 is conveyed to the developer discharge port 8a. Therefore, the deteriorated developer is gradually discharged from the developer discharge port 8a.

The developer in the supply chamber 3 is attracted to the surface of the first developing sleeve 21b by the magnetic force of the pickup magnetic pole N11. The trimming magnetic pole S11 causes the developer to stand toward the trimmer 31, that is, a so-called spiked state. The trimmer 31 is in contact with the developer that has risen, and regulates the thickness of the developer layer on the surface of the first developing sleeve 21b.
The developer that has passed through the trimmer 31 is conveyed to a region between the transfer magnetic pole N12 and the reception magnetic poles S21 and N21 as the first developing sleeve 21b rotates.

  The developer on the surface of the first developing sleeve 21b receives the magnetic force of the magnetic field generated between the transfer magnetic pole N12 and the first receiving magnetic pole S21, and a part of the developer is on the second developing sleeve 22b side. Move to. At this time, each magnetic pole N12, so that half of the developer on the first developing sleeve 21b moves to the surface of the second developing sleeve 22b and the remaining developer remains on the first developing sleeve 21b. The magnetic force of S21 and N21 is set.

Along with the rotation of the photosensitive drum PR, the latent image on the surface of the photosensitive drum PR sequentially passes from the second developing area Q2b to the first developing area Q2a and is developed into a visible image. Accordingly, the latent image on the surface of the photosensitive drum PR is developed by the two developing rolls 21 and 22.
Therefore, with the development of the developing device G according to the first embodiment, the development failure is caused by two developments compared to the configuration in which the development failure may occur in one development due to the high speed rotation of the photosensitive drum PR. The occurrence of is reduced.

The developer that has not been consumed in the first developing region Q2a is attached to the surface of the first developing sleeve 21b, and the magnetic force between the pick-off magnetic pole N14 and the pick-up magnetic pole N11 is at the minimum position. Detach from the developing sleeve 21b. The developer separated from the first developing sleeve 21 b is returned to the supply chamber 3. The developer returned to the supply chamber 3 is conveyed while being stirred by the supply auger 17. The developer in the supply chamber 3 is adsorbed by the first developing roll 21 and reused, or conveyed to the admix chamber 2 and circulated.
The developer that has not been consumed in the second development region Q2b is transported downstream while being held on the surface of the second development sleeve 22b by receiving the magnetic force of the third transport magnetic pole N22. The developer on the second developing sleeve 22 b is detached from the second developing sleeve 22 b at the position of the chute 33. The developer separated from the second developing sleeve 22 b is guided along the chute 33 and flows into the storage chamber 13. The paddle 18 returns the developer that has flowed into the storage chamber 13 to the supply chamber 3.

FIG. 5 is an explanatory view of the vicinity of a trimmer in a conventional developing roll.
In FIG. 5, in the conventional developing roll 01, the trimming magnetic pole S03 is set at a position of 145.5 ° as an example from the reference position 04 in the reverse rotation direction with respect to the rotation direction of the developing sleeve 02. N06 is set at a position of 166 ° in the forward rotation direction from the reference position 04. Therefore, the position 07 at which the magnetic force is minimized between the trimming magnetic pole S03 and the pickup magnetic pole N06 is a position away from the lower end 08a of the holder 08.

6 is an explanatory diagram of the magnetic profile and the magnetic force. FIG. 6A is a graph in which the horizontal axis indicates the phase and the vertical axis indicates the magnetic flux density in the conventional configuration shown in FIG. 5, and FIG. 6C is a graph in which the horizontal axis represents the phase and the vertical axis represents the magnetic force, and FIG. 6C is a graph in which the horizontal axis represents the phase and the vertical axis represents the magnetic flux density in the first embodiment. 6D is a graph in which the horizontal axis indicates the magnetic force in Example 1 and the vertical axis indicates the magnetic force.
In FIG. 6, the solid line indicates the magnetic flux density and magnetic force in the normal direction (radial direction), and the broken line indicates the magnetic flux density and magnetic force in the tangential direction (circumferential direction).
In FIG. 6, in the conventional configuration shown in FIG. 5, the distance between the pickup magnetic pole N06 and the trimming magnetic pole S03 is relatively narrow. Therefore, as shown in the waveform in the normal direction of FIG. 6B, the magnetic force does not become zero even at the position 07 where the magnetic force is minimum between the pickup magnetic pole N06 and the trimming magnetic pole S03. Therefore, there is a certain amount of magnetic force even at the position 07 where the position is minimized, and a stronger magnetic force acts on the upstream side and the downstream side of the position 07 where the position is minimized than the position 07 where the position is minimized.

  Therefore, in the conventional configuration shown in FIG. 5, even if the developer, which is regulated by the trimmer 09 and cannot pass through the gap between the trimmer 09 and the developing sleeve 02, returns to the lower container side, the magnetic force is first minimized. It is held by the magnetic force at the position 07 and is difficult to fall downward. In addition, even if the magnetic force falls downward from the position 07 at which the magnetic force is minimal, the space 010 below the position 07 at which the magnetic force is minimal and above the lower end 08a of the holder 08 is more than the position 07 at which the magnetic force is minimal. Strong and easy to hold by magnetic force. Therefore, the developer tends to stay in the wedge-shaped space 010 surrounded by the developing sleeve 02, the trimmer 09, and the holder 08.

In particular, in the configuration having two developing rolls, an area for transferring the developer is required between the trimming magnetic pole and the first developing magnetic pole. Therefore, it is difficult to ensure a sufficient space between the trimming magnetic pole and the pickup magnetic pole. In such a case, the magnetic force at the position 07 at which the magnetic field is minimized is minimal, but the absolute value of the magnetic force tends to be larger than when the trimming magnetic pole and the pickup magnetic pole are sufficiently separated from each other. Therefore, the developer is easily held even at the position 07 where the magnetic force is minimal, and the developer tends to stay in the wedge-shaped space 010.
The developer staying in the wedge-shaped space 010 is pushed by the developer conveyed from the upstream as the developing sleeve 02 rotates. Therefore, the pressure of the developer entering the trimmer 09 becomes excessive, and there is a possibility that an excessive amount of developer passes through the trimmer 09 than a preset amount. Further, when the staying developer is pushed by the developer conveyed from the upstream side, the developer is easily deteriorated due to a load, so-called stress. Furthermore, if the developer stays for a long time, problems such as a decrease in fluidity and the amount of charged electric charge also occur. If an excessive amount of developer passes, deteriorates, or has a decreased fluidity, development failure may occur.

On the other hand, in the first developing roll 21 of the first embodiment, as shown in FIG. 4, the position 51 where the magnetic force is minimized between the trimming magnetic pole S11 and the pickup magnetic pole N11 and the first developing roll 21. A lower end portion 32b of the guide portion 32a of the holder 32 is disposed on an extension line of the imaginary line segment 37 connecting the rotation center 21c. Then, as shown in FIG. 6D, the magnetic force is close to zero at the position 51 where the magnetic force is minimized as compared with the conventional configuration.
In particular, in the first embodiment, as shown in FIG. 6C, the waveform between the trimming magnetic pole S11 and the pickup magnetic pole N11 is different from the conventional configuration shown in FIG. 6A. In other words, between the sine waveform of the magnetic flux density from the trimming magnetic pole S11 and the sine waveform of the magnetic flux density from the pickup magnetic pole N11, the magnetic flux density decreases more rapidly than the sine waveform in the vicinity of the position 37a at which it is minimized. The waveform is close to a cubic curve. Therefore, the magnet roll 21a is configured so as to have a magnetic flux density profile in which two inflection points 51 and 52 connecting two sinusoidal waveforms and a cubic curve are present. Therefore, in Example 1, compared with the conventional configuration, the magnetic force tends to approach zero as shown in FIG. 6D at the position 37a where the magnetic force is minimal.

  Therefore, when the developer regulated by the trimmer 31 flows to the lower end portion 32b along the guide portion 32a, the magnetic force becomes minimum at the position of the lower end portion 32b. Therefore, the developer easily falls into the supply chamber 3. Therefore, the retention of the developer in the wedge-shaped space is reduced as compared with the conventional configuration in which the position 51 where the magnetic force is minimized does not correspond to the lower end portion 32b. Further, compared with the conventional configuration in which the magnetic force does not become zero even at the position 07 at which the magnetic force is minimal, the developer is hardly held by the magnetic force in the configuration of Example 1 at the position 37a where the magnetic force is minimal and close to zero. Therefore, the retention of the developer is also reduced. Therefore, excessive passage and deterioration of the developer and occurrence of poor development are also reduced.

In the first embodiment, the lower end portion 32 b is disposed below the rotation center 21 c of the developing roll 21 in the gravity direction. Here, the supply auger 17 of the first embodiment rotates from the upper side to the lower side on the developing roll 21 side. Therefore, at the upper end of the supply auger 17, the developer pushed by the second conveying blade 17 b as the supply auger 17 rotates is sent from the left to the right. Here, when the lower end portion 32b is disposed above the rotation center 21c of the developing roll 21 in the gravity direction, the developer pushed by the second conveying blade 17b is held by the first developing sleeve 21b. There is a risk of entering the wedge-shaped space directly. In this case, the developer in the wedge-shaped space becomes excessive, and the developer is likely to deteriorate due to stress.
On the other hand, in Example 1, the holder 32 in which the lower end portion 32b is arranged below the rotation center of the developing roll 21 in the gravity direction suppresses the developer from entering the wedge-shaped space. Therefore, deterioration of the developer is suppressed.

FIG. 7 is an explanatory diagram of the magnetic field in the region where the developer is transferred, FIG. 7A is an explanatory diagram of the magnetic field in the conventional configuration, and FIG. 7B is an explanatory diagram of the magnetic field in the configuration of the first embodiment.
In FIG. 7A, in the configuration in which the developer is transferred from the first developing roll 011 to the second developing roll 012 in the conventional developing device, the receiving magnetic pole 013 is opposed to the receiving magnetic pole 013 and has a polarity opposite to that of the transferring magnetic pole 013. A magnetic pole 014 is arranged. Further, a trimmer 016 for distributing the developer is disposed in a gap between the delivery magnetic pole 013 and the reception magnetic pole 014. In this configuration, the developer is distributed according to the balance of magnetic force in the magnetic field between the transfer magnetic pole 013 and the reception magnetic pole 014 and the gap between the trimmer 016 and the rolls 011 and 012. Therefore, the developer that could not pass through the position of the trimmer 016 is held in the magnetic field between the transfer magnetic pole 013 and the reception magnetic pole 014 and tends to stay in the space between the transfer magnetic pole 013 and the reception magnetic pole 014. If the developer stays in the space between the delivery magnetic pole 013 and the reception magnetic pole 014, the developer is subject to load and stress, and the developer is likely to deteriorate. Also, when the developer is regulated by the trimmer 016, the developer is likely to deteriorate due to stress. When the developer deteriorates, the fluidity and the charge amount are likely to fluctuate, and the toner density of the developer tends to fluctuate. If the fluidity or the like fluctuates, the amount of developer passing through the trimmer 016 may fluctuate, which may lead to development failure.
Further, in the configuration using the trimmer 016, there is a possibility that the amount of the developer may fluctuate due to a manufacturing error or an assembly error in the interval between the developing rolls 011 and 012 and the trimmer 016 and the accuracy of the positions of the magnetic poles 013 and 014.

On the other hand, in the developing device G of Example 1, in the region where the developer is transferred from the first developing roll 21 to the second developing roll 22, one transfer magnetic pole N12 and two different polarities are provided. Receiving magnetic poles S21 and N21 are arranged. Accordingly, a magnetic field 42 attracted between the transfer pole N12 and the first reception pole S21 having opposite polarities is formed, and repulsion is generated between the transfer pole N12 and the second reception pole N21 having the same polarity. A magnetic field 43 is formed. Therefore, the delivery of the developer is promoted between the delivery magnetic pole N12 and the first reception magnetic pole S21, and the delivery of the developer is restricted between the delivery magnetic pole N12 and the second reception magnetic pole N21. .
The developer that has moved to the surface of the second developing roll 22 is held on the second developing roll 22 by a magnetic field 44 formed between the first receiving magnetic pole S21 and the second receiving magnetic pole N21. The That is, in the second developing roll 22 of the first embodiment, the developer that can be held by the magnetic field 44 between the receiving magnetic poles S <b> 21 and N <b> 21 is attracted to the first developing roll 21. Therefore, in the conventional configuration, there is a possibility that the width of the gap varies due to installation errors of the second developing roll 012 and the trimmer 016, and the amount of developer held on the surface of the second developing roll 012 varies. Although there is a fear, in the developing device G of Example 1, the amount of developer that can be held by the magnetic field 44 is held by the second developing roll 22. Therefore, the amount of developer held on the surface of the second developing roll 22 is easily stabilized.

  Further, in the developing device G of Example 1, not only the delivery of the developer is promoted but also the delivery of the developer to the region where the developer is delivered from the first development roll 21 to the second development roll 22. There is also a limited magnetic field 43. Accordingly, in the region where the developer is delivered, the magnetic field 43 whose delivery is restricted suppresses the holding of the developer, and the developer stay is suppressed. Therefore, compared with the conventional configuration, the stress accompanying the retention of the developer is reduced.

In particular, in the first exemplary embodiment, the first receiving magnetic pole S21 is disposed on the upstream side and the second receiving magnetic pole N21 is disposed on the downstream side with respect to the rotation direction of the second developing roll 22. Therefore, after the delivery of the developer is promoted on the upstream side, the delivery of the developer is limited on the downstream side. Therefore, on the downstream side in the rotation direction of the second developing roll 22, the magnetic field 43 that restricts the delivery of the developer is not generated between the developing rolls 21 and 22 even if the trimmer 016 is not disposed. Suppresses the movement of the developer. Further, in the developing device G of Example 1, after the developer is moved by the magnetic field 42 that attracts the upstream side, the developer is easily divided and distributed by the repulsive magnetic field 43 on the downstream side. It has become.
Therefore, the developer is stably distributed in a state in which the stress applied to the developer is reduced as compared with the configuration in which the developer layer is physically distributed using the trimmer 016. Therefore, as compared with the conventional configuration, the deterioration of the developer can be suppressed and stable distribution is possible.

Furthermore, in the developing device G of Example 1, two magnetic poles S21 and N21 are arranged on the second developing roll 22 that rotates in the against direction with respect to the photosensitive drum PR in the second developing region Q2b. . Here, the second developing roll 22 rotating in the against direction has a higher relative speed with respect to the surface of the photosensitive drum PR than the first developing roll 21 rotating in the with direction with respect to the photosensitive drum PR. Become. Accordingly, in the second development region Q2b, the development conditions become severe as the rotational speed of the photosensitive drum PR and the second development roll 22 increases. Therefore, when the amount of the developer held on the surface of the second developing roll 22 varies as compared with the first developing roll 21, the image quality is likely to be affected.
Here, in the region where the developer is transferred, two magnetic poles S21 and N21 are arranged on the side where the two magnetic poles S21 and N21 are arranged and on the side where the one magnetic pole N12 is arranged. On the side, the developer amount is more likely to be stabilized by the magnetic field 44 between the two magnetic poles S21 and N21. In the developing device G of Example 1, two magnetic poles S21 and N21 are disposed on the second developing roll 22 that rotates in the against direction, and the developer held on the surface of the second developing roll 22 is maintained. It is easy to stabilize the amount, and it can cope with high-speed rotation and high image quality.

  In the developing device G according to the first embodiment, the first receiving magnetic pole S21 is disposed at a position shifted upstream from the closest position 41 between the first developing sleeve 21b and the second developing sleeve 22b. ing. Therefore, compared with the conventional configuration, the magnetic field 42 between the first receiving magnetic pole S21 and the passing magnetic pole N12 is less likely to reach the closest position 41. If the developing rolls 011 and 012 have eccentricity, curvature, and the like, the closest position 41 is likely to be affected by the gap becoming wider or narrower. Therefore, when the magnetic field delivered to the closest position 41 is generated as in the conventional configuration, the amount of developer delivered is likely to fluctuate. On the other hand, in the developing device G of the first embodiment, the magnetic field 42 approaching the closest position 41 is reduced and the influence of the curvature of the developing rolls 21 and 22 is reduced. Therefore, it is possible to stabilize the amount of developer delivered.

Further, in the developing device G of Example 1, the first developing magnetic pole N13 and the second developing magnetic pole S22 are composed of magnetic poles having the same polarity. Therefore, when the two developing magnetic poles have different polarities, a magnetic field is likely to be generated between the two magnetic poles. In particular, when the developing device G is downsized and the two developing rolls 21 and 22 approach each other, the influence of the magnetic field between the developing magnetic poles is likely to occur. When a magnetic field is generated between the developing magnetic poles, the developer is easily held in the space between the developing magnetic poles, and the held developer may scrape off the image on the surface of the photosensitive drum PR. On the other hand, in the first embodiment, the developing magnetic poles S12 and S22 are configured with the same polarity, so that the developer is prevented from being held in the space between the developing magnetic poles S12 and S22.
Further, in the first embodiment, the second developing magnetic pole S22 is disposed on the downstream side in the rotation direction of the photosensitive drum PR with respect to the closest position between the second developing roll 22 and the photosensitive drum PR. . Therefore, at the closest position, the developer is not in a state of being lined up along the lines of magnetic force, that is, in a so-called spiked state. When the developer is spiked at the closest position, when the developer spikes at the closest position where the gap is the narrowest, the pressure of the developer applied to the surface of the photosensitive drum PR increases. Therefore, there is a possibility that an image defect such as an image being scraped off may occur. On the other hand, in the first embodiment, the second developing magnetic pole S22 is disposed on the downstream side in the rotation direction of the photosensitive drum PR with respect to the closest position, and the pressure is excessive at the closest position. It is suppressed.

  Further, in Example 1, the head is raised at the position of the developing magnetic pole S22 on the downstream side in the rotation direction of the photosensitive drum PR, and not only on the closest position but also on the downstream side in the rotation direction of the photosensitive drum PR. Development is possible in a wide area. Therefore, even if the rotational speed of the photosensitive drum PR and the second developing roll 22 is increased, the development can be stably performed in the second developing region Q2b having a width along the rotational direction of the photosensitive drum PR. Is possible. Further, if the second development area Q2b has a width, even if a visible image immediately after development is scraped upstream of the second development area Q2b, the second development area Q2b It is possible to develop again on the downstream side. Therefore, it is possible to suppress the occurrence of defective development.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is made in the range of the summary of this invention described in the claim. Is possible. Modification examples (H01) to (H012) of the present invention are exemplified below.
(H01) In each of the above embodiments, the copying machine U is illustrated as an example of the image forming apparatus, but the present invention is not limited to this. For example, the present invention can be applied to a printer as an example of an image forming apparatus, a FAX, or a multifunction machine having a plurality of these functions. Further, the present invention is not limited to a single color image forming apparatus, and can be applied to a multicolor image forming apparatus.

(H02) In the above-described embodiment, the rotation direction of the first developing roll 21 is not limited to the Against direction, and may be the with direction.
(H03) In the above embodiment, it is desirable to arrange one magnetic pole N12 on the developing roller 22 on the side and two magnetic poles S21 and N21 on the developing roller 21 on the gainst side in the transfer area. The reverse is also possible.
(H04) Of the receiving magnetic poles S21 and N21 in the above embodiment, it is desirable that the magnetic pole S21 having the opposite polarity to the delivery magnetic pole N12 is disposed on the upstream side, and the magnetic pole N21 having the same polarity is disposed on the downstream side. It is also possible to arrange the magnetic pole S21 of the same polarity on the downstream side and arrange the magnetic pole N21 of the same polarity on the upstream side.

(H05) In the embodiment, it is desirable to arrange the first receiving magnetic pole S21 at a position shifted from the closest position, but it is also possible to arrange it corresponding to the closest position.
(H06) In the embodiment described above, the configuration of the admix chamber 2, the supply chamber 3, the storage chamber 13, the augers 16, 17, the paddle 18, and the chute 33 is not limited to the configuration illustrated in the embodiment. For example, arbitrary changes are possible, such as a configuration in which the developer flows from the storage chamber 13 into the admix chamber 2 or a configuration similar to the augers 16 and 17 of the paddle 18.

(H07) In the above-described embodiment, it is desirable that the same trimmer as in the prior art is not arranged, but a trimmer as an example of a sorting auxiliary member is installed as an auxiliary member to the present invention. It is also possible to do.
(H08) In the above-described embodiment, the polarities such as N and S and the positions and numbers of the magnetic poles are not limited to the configurations exemplified in the embodiments. It can be changed arbitrarily according to the design and specifications.
(H09) In the embodiment, the position of the lower end 32b of the holder 32 is desirably lower in the direction of gravity than the rotation center 21c of the first developing roll 21, but is not limited thereto. It is also possible to dispose the lower end 32b upward in the direction of gravity with respect to the rotation center 21c.

(H010) In the embodiment described above, the arrangement of the trimming magnetic pole S11, the pickup magnetic pole N11, the lower end portion 32b of the holder 32, etc. is more effective in the configuration having the two developing rolls 21 and 22. However, the present invention is not limited to this. Not. The present invention can also be applied to a configuration having only one developing roll. Further, the present invention can be applied to a developing device having three or more developing rolls.
(H011) In the above embodiment, it is desirable to provide two receiving magnetic poles S21 and N21, but the present invention is not limited to this. Similar to the conventional configuration, a configuration in which one receiving magnetic pole and a trimmer are arranged is also possible.
(H012) In the above-described embodiment, the number of magnetic poles is exemplified as a configuration in which seven poles are arranged in each of the developing rolls 21 and 22. However, the present invention is not limited to this. The number of transport magnetic poles can be increased or decreased according to design, specifications, etc., and can be 6 poles or less or 8 poles or more.

1 ... container,
21. Developing member,
21a ... magnet member,
21b ... Rotating body,
21c ... the center of rotation of the rotating body,
22 ... Second developing member,
22a ... second magnet member,
22b ... the second rotating body,
31 ... restricting member,
32a ... Guide part,
32b ... the end,
37 ... Line segment,
37a ... minimal position,
F: Fixing device,
G: Developing device,
N11: magnetic pole for adsorption,
PR: Image carrier,
ROS ... latent image forming device,
S ... medium
S11: Magnetic pole for regulation,
TU ... Transfer device,
U: Image forming apparatus.

Claims (3)

A container for containing a developer;
A developing member disposed opposite to the image holding member, the rotating member holding the developer for developing the latent image on the surface of the image holding member into a visible image, and the rotating member; A magnetic member disposed inside and having a plurality of magnetic poles for generating magnetic force for attracting the developer in the container to the surface of the rotating body; and
A developer that is disposed on the upstream side of the position facing the image holding member with respect to the rotation direction of the rotating member, is disposed in the vicinity of the surface of the rotating member, and is held on the surface of the rotating member. A regulating member that regulates the amount of
A regulating magnetic pole arranged corresponding to the regulating member, and an adsorption arranged upstream of the regulating magnetic pole with respect to the rotation direction of the rotating body and adsorbing developer on the surface of the rotating body The magnetic member having at least a magnetic pole for,
The developer regulated by the regulating member, a guide portion for guiding toward the container, the lower end portion of the guide portion, the magnetic force between the magnetic pole and the magnetic pole for adsorption for the regulation The guide unit disposed on an extension line of a virtual line segment connecting a minimal position and the rotation center of the rotating body;
The regulating magnetic pole disposed above in the direction of gravity with respect to the rotation center of the rotating body;
The magnetic pole for adsorption disposed below the rotation center of the rotating body in the direction of gravity and adjacent to the magnetic pole for regulation;
A lower end portion of the guide portion disposed below the rotation center of the rotating body in the gravitational direction and above the attracting magnetic pole in the gravitational direction;
A developing device comprising: A second developing member disposed on the upstream side of the developing member with respect to the rotation direction of the image holding member and facing the image holding member; A second rotating body that rotates while holding the developer to be developed into a visual image, and a magnetic force that is disposed inside the second rotating body and that attracts the developer to the surface of the second rotating body A second magnet member having a plurality of magnetic poles for generating a magnetic field, and developing from the rotating body to the second rotating body in a region where the rotating body of the developing member and the second rotating body face each other. The second developing member on which the magnetic pole for moving the agent is disposed;
The developing device according to claim 1, further comprising: An image carrier,
A latent image forming apparatus for forming a latent image on the image carrier;
The developing device according to claim 1 or 2 , wherein the latent image of the image carrier is developed into a visible image;
A transfer device for transferring a visible image of the image carrier to a medium;
A fixing device for fixing the visible image transferred to the medium;
An image forming apparatus comprising:

Images