JP2019101349A - Developing device and image forming device equipped with the same - Google Patents

Abstract

To provide a developing device with which it is possible to stabilize the shift of the amount of a developer in a developer container and realize downsizing, and an image forming device equipped with the same.SOLUTION: The developing device comprises a developer container including a first conveyance chamber and a second conveyance chamber arranged upward of the first conveyance chamber, a first stirring-conveying member for conveying a developer in the first conveyance chamber in a fist direction, a second stirring-conveying member for conveying a developer in the second conveyance chamber in a second direction, and a developer carrier. The developer container includes a first and a second communication unit for communicating the first conveyance chamber with the downstream ends in first and second directions of the second conveyance chamber, respectively, and a bypass conveyance path for communicating the first and the second conveyance chambers with each other downstream of the second communication unit in the second direction. The second stirring-conveying member includes a conveyance blade for conveying the developer in the second conveyance chamber in the second direction, and a stirring restriction unit formed downstream of the conveyance blade in the second direction. The stirring restriction unit is arranged downstream of the second communication unit and upstream of the bypass conveyance path in the second direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a developing device and an image forming apparatus including the same, and in particular, a first conveyance chamber in which a stirring conveyance member for stirring and conveying a developer is disposed, and a first conveyance chamber disposed above the first conveyance chamber The present invention relates to a developing device having two conveyance chambers, and an image forming apparatus provided with the same.

  In an image forming apparatus, a latent image formed on an image carrier made of a photosensitive member or the like is developed by a developing device and visualized as a toner image. As such a developing device, a developing container for containing a developer, a first stirring conveyance member and a second stirring conveyance member for stirring and conveying the developer, and a development for carrying the developer supplied from the second stirring conveyance member There is known a developing device provided with a roller (developer carrier). The first stirring and conveying member conveys the developer to one side in the axial direction of the developing roller, and the second stirring and conveying member supplies the developer to the developing roller while conveying the developer to the other side (the side opposite to the one side) Do.

  In recent years, there has been an increasing demand for downsizing of the image forming apparatus, and in particular, in a color machine, a plurality of developing devices are disposed, so downsizing of the developing device is required. Therefore, a first conveyance chamber in which the first stirring and conveying member is disposed inside, and a second conveyance chamber in which the second stirring and conveying member is disposed inside the first conveyance chamber are provided. Developing devices are known. In this developing device, it is possible to miniaturize the developing device in the horizontal direction by arranging the first transfer chamber and the second transfer chamber up and down. For this reason, since it is possible to reduce the arrangement space of the developing device, it is possible to miniaturize the image forming apparatus.

  For example, Patent Document 1 has a communication path through which the developer is delivered from the developing chamber to the stirring chamber by the developer falling from the downstream side of the developing chamber in the developer conveyance direction to the upstream side of the developer conveying direction in the stirring chamber. There is disclosed a developing device in which a replenished developer replenished from a developer replenishing port above the stirring chamber falls onto a region where the communication paths in the stirring chamber merge.

JP, 2006-47884, A

  In the developing device in which the first transfer chamber and the second transfer chamber as described above are arranged up and down, the portion from which the developer is pushed against the gravity from the first transfer chamber to the second transfer chamber and the second transfer chamber There is a place where the developer falls to the first conveyance chamber by gravity. Therefore, when the flowability of the developer changes due to factors such as durability printing and environmental fluctuations, the circulation balance of the developer tends to change, and the developer tends to be biased in the developing device. As a result, insufficient supply of the developer to the developing roller in the developer conveyance direction upstream of the second conveyance chamber with a small amount of developer, and developer in the developer conveyance direction downstream of the second conveyance chamber with a large amount of developer. There is a problem that compression and retention of the

  Also, a method of alleviating the compression and stagnation of the developer on the downstream side of the developer conveyance direction of the second conveyance chamber by enlarging the opening diameter of the communication portion where the developer falls from the second conveyance chamber to the first conveyance chamber. Is also conceivable. However, in order to increase the opening diameter of the communication portion, it is necessary to extend the second transfer chamber and the first transfer chamber in the longitudinal direction, which leads to an increase in the size of the developing device.

  In view of the above problems, it is an object of the present invention to provide a developing device capable of stabilizing transition of the amount of developer in a developing container and realizing downsizing and an image forming apparatus provided with the developing device. And

  In order to achieve the above object, a first configuration of the present invention is a developing device provided with a developing container, a first stirring and conveying member, a second stirring and conveying member, and a developer carrier. The developing container has a first transfer chamber, and a second transfer chamber disposed above the first transfer chamber with the partition portion interposed therebetween, and stores a two-component developer including a carrier and a toner. The first stirring and conveying member is rotatably supported in the first conveyance chamber, and stirs and conveys the developer in the first conveyance chamber in the first direction. The second stirring and conveying member is rotatably supported in the second conveyance chamber in parallel with the first stirring and conveying member, and rotates in the opposite direction to the first stirring and conveying member to rotate the developer in the second conveyance chamber. Stirring and conveying in the second direction which is the direction opposite to the one direction. The developer carrier is rotatably supported by the developer container and carries the developer in the second transfer chamber on the surface. The developing container includes a first communicating portion communicating downstream end portions of the first transfer chamber and the second transfer chamber in the first direction, and a downstream end portion of the first transfer chamber and the second transfer chamber in the second direction. A second communication portion communicating with each other, and a bypass conveyance provided downstream of the second communication portion in the second direction and communicating downstream end portions of the first conveyance chamber and the second conveyance chamber in the second direction And a path. The second stirring / conveying member is formed on the rotating shaft and the outer peripheral surface of the rotating shaft, and is for conveying and agitating the developer in the second conveying chamber in the second direction, and the downstream side of the conveying blade in the second direction And a stirring restricting portion configured of a conveying blade that conveys the developer in the first direction. The stirring regulation portion is disposed downstream of the second communication portion with respect to the second direction and upstream of the bypass conveyance path.

  According to the first configuration of the present invention, the developer conveyed to the downstream end of the second conveyance chamber is blocked by the stirring regulation portion in a situation where the developer stagnating around the second communication portion is small And fall into the first transfer chamber via the second communication portion. On the other hand, in a situation where the amount of developer accumulated around the second communication portion increases, a part (remaining portion) of the developer conveyed to the downstream end of the second conveyance chamber passes over the stirring regulation portion and the bypass conveyance path It flows in. Therefore, the amount of developer in the second conveyance chamber is stabilized, so that the supply unevenness of the developer to the developer carrier does not occur, and a stable image can be maintained for a long time. Further, since the pressure acting on the developer at the downstream end of the second transfer chamber in the second direction is reduced, the compression action of the developer at the upstream end of the first transfer chamber in the first direction is also reduced. . As a result, it is possible to suppress the aggregation of the developer and the increase in the driving torque of the first stirring and conveying member associated therewith.

FIG. 1 is a schematic cross-sectional view showing the entire configuration of a color printer 100 provided with the developing devices 3a to 3d of the present invention Side surface sectional view showing the structure of the developing device 3a according to the first embodiment of the present invention Longitudinal sectional view showing the structure of the stirring unit of the developing device 3a of the first embodiment A partial enlarged view around the second communication portion 22f in FIG. 3 Side surface sectional view showing the structure of the developing device 3a according to the second embodiment of the present invention Longitudinal sectional view showing the structure of the stirring unit of the developing device 3a of the second embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a color printer 100 provided with the developing devices 3a to 3d of the present invention, and shows a tandem type color printer here. In the main body of the color printer 100, four image forming portions Pa, Pb, Pc and Pd are disposed in the order of Pd to Pa from the upstream side in the transport direction (right side in FIG. 1). These image forming portions Pa to Pd are provided corresponding to images of four different colors (black, yellow, magenta and cyan), and are cyan, magenta and yellow respectively according to the steps of charging, exposure, development and transfer. And black images are sequentially formed.

  Photosensitive drums 1a, 1b, 1c and 1d for carrying visible images (toner images) of respective colors are disposed in these image forming portions Pa to Pd, respectively, and are further rotated clockwise in FIG. An intermediate transfer belt 8 is provided adjacent to each of the image forming portions Pa to Pd.

  When image data is input from a host device such as a personal computer, first, the surfaces of the photosensitive drums 1a to 1d are uniformly charged by the chargers 2a to 2d. Next, the surfaces of the photosensitive drums 1a to 1d are irradiated with light according to the image data by the exposure device 5, and electrostatic latent images corresponding to the image data are formed on the respective photosensitive drums 1a to 1d. In the developing devices 3a to 3d, two-component developers (hereinafter, also simply referred to as developers) including toners of respective colors of black, yellow, magenta and cyan supplied from the toner containers 4a to 4d and magnetic carriers are located. It has been quantitatively filled. Toners in the developer are supplied onto the photosensitive drums 1a to 1d by the developing devices 3a to 3d and electrostatically adhere to the photosensitive drums 1a to 1d. Thus, a toner image corresponding to the electrostatic latent image formed by the exposure from the exposure device 5 is formed.

  Then, an electric field is applied between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d at a predetermined transfer voltage by the primary transfer rollers 6a to 6d, and black, yellow, magenta, and the like on the photosensitive drums 1a to 1d. The cyan toner image is primarily transferred onto the intermediate transfer belt 8. The toner and the like remaining on the surfaces of the photosensitive drums 1a to 1d after the primary transfer are removed by the cleaning devices 7a to 7d.

  A transfer sheet P to which a toner image is transferred is accommodated in a sheet cassette 16 disposed in the lower part of the color printer 100. The transfer sheet P is a nip portion between the secondary transfer roller 9 and the intermediate transfer belt 8 provided adjacent to the intermediate transfer belt 8 at a predetermined timing via the sheet feeding roller 12a and the registration roller pair 12b (secondary transfer nip To the department). The transfer sheet P on which the toner image is secondarily transferred is conveyed to the fixing unit 13.

  The transfer paper P conveyed to the fixing unit 13 is heated and pressed by passing through the nip portion between the fixing belt and the pressure roller, and the toner image is fixed on the surface of the transfer paper P, and a predetermined full color image is obtained. It is formed. The transfer paper P on which the full color image is formed is discharged as it is (or after it is distributed to the reverse conveying path 18 by the branch portion 14 and the image is formed on both sides) by the discharge roller pair 15 to the discharge tray 17.

  FIG. 2 is a side sectional view showing the configuration of the developing device 3 a according to the first embodiment of the present invention mounted on the color printer 100. Although the developing device 3a disposed in the image forming portion Pa of FIG. 1 will be described here, the configuration of the developing devices 3b to 3d disposed in the image forming portions Pb to Pd is basically the same. Omit. Further, FIG. 2 shows the developing device 3a as viewed from the back side of FIG. 1, and the arrangement of each member in the developing device 3a is opposite to that in FIG. As shown in FIG. 2, the developing device 3 a includes a developing roller (developer carrier) 20, a stirring conveyance member 42, and a developing container 22.

  The developing container 22 constitutes an outer shell of the developing device 3a, and is partitioned by a partitioning portion 22b into a first transfer chamber 22c and a second transfer chamber 22d disposed above the first transfer chamber 22c. In the first transfer chamber 22c and the second transfer chamber 22d, a two-component developer including a carrier and a toner is accommodated. Further, the developing container 22 rotatably holds the stirring and conveying member 42 and the developing roller 20. Further, the developing container 22 is formed with an opening 22a for exposing the developing roller 20 toward the photosensitive drum 1a.

  The stirring and conveying member 42 is configured of two, a first spiral (first stirring and conveying member) 43 and a second spiral (second stirring and conveying member) 44. The first spiral 43 is rotatably supported in the first transfer chamber 22c. The second spiral 44 is rotatably supported in the second transfer chamber 22d.

  The first spiral 43 and the second spiral 44 stir the developer to charge the toner in the developer to a predetermined level. Thus, the toner is held by the carrier. At both end portions in the longitudinal direction (direction perpendicular to the sheet of FIG. 2) of the partition 22b separating the first transfer chamber 22c and the second transfer chamber 22d, the communicating portions (the first communicating portion 22e of FIG. 3 and A second communicating portion 22f) is provided. When the first spiral 43 and the second spiral 44 rotate, the developer is conveyed from one communication portion (first communication portion 22e) provided in the partition 22b to the second spiral 44, and the other communication portion (second communication) The developer is conveyed from the portion 22f) to the first spiral 43, and the developer circulates in the first transfer chamber 22c and the second transfer chamber 22d. Then, the developer is supplied from the second spiral 44 to the developing roller 20, and a magnetic brush is formed on the developing roller 20.

  The developing roller 20 includes a developing sleeve 20a rotatably supported by the developing container 22, and a magnetic pole member 20b fixed to a fixed shaft (not shown) and having a plurality of magnetic poles. In the vicinity of the developing sleeve 20a, a regulating blade 21 disposed at a predetermined distance from the developing sleeve 20a and regulating the thickness of the magnetic brush on the surface of the developing sleeve 20a is provided. The developing sleeve 20a is rotated in the direction of the arrow in FIG. 2 (counterclockwise direction) by a drive mechanism including a motor and a gear (not shown). Further, a developing bias in which an AC voltage is superimposed on a DC voltage is applied to the developing sleeve 20a.

  When the developing sleeve 20a to which the developing bias is applied rotates in the counterclockwise direction in FIG. 2, the potential difference between the developing bias potential and the potential of the exposed portion of the photosensitive drum 1a causes the magnetic brush to carry on the surface of the developing sleeve 20a. The toner moves to the photosensitive drum 1a. The toner sequentially adheres to the exposed portion on the photosensitive drum 1a rotating in the clockwise direction, and the electrostatic latent image on the photosensitive drum 1a is developed.

  FIG. 3 is a longitudinal sectional view (a cross-sectional view taken along the line YY 'in FIG. 2) showing the structure of the stirring portion of the developing device 3a of the first embodiment. As shown in FIG. 3, in the developing container 22, a partition 22b, a first transfer chamber 22c, a second transfer chamber 22d, a first communicating portion 22e, and a second communicating portion 22f are formed. .

  The partition portion 22 b extends in the longitudinal direction of the developing container 22 and divides the first transfer chamber 22 c and the second transfer chamber 22 d vertically in parallel. The first communication portion 22e and the second communication portion 22f are respectively formed on one side and the other side (the downstream side in the A1 direction and the downstream side in the A2 direction) of the partition portion 22b in the longitudinal direction. The first communicating portion 22 e communicates downstream end portions of the first transfer chamber 22 c and the second transfer chamber 22 d in the A1 direction (first direction). The second communication portion 22 f communicates the downstream end portions of the first transfer chamber 22 c and the second transfer chamber 22 d in the A2 direction (second direction). The developer circulates in the first transfer chamber 22c, the first communication portion 22e, the second transfer chamber 22d, and the second communication portion 22f.

  The first spiral 43 disposed in the first transfer chamber 22c is integrally formed with the rotation shaft 43b and the rotation shaft 43b, and is formed in a spiral shape at a constant pitch in the axial direction of the rotation shaft 43b. And a spiral blade 43a. The rotation shaft 43 b is rotatably supported by the developing container 22. The first spiral blade 43a conveys the developer in the first conveyance chamber 22c in the A1 direction (one side in the axial direction of the developing roller 20) while stirring the developer by rotating in the clockwise direction in FIG.

  Further, at the upstream end (right end in FIG. 3) of the first transfer chamber 22c in the A1 direction, a toner replenishing port 23 for replenishing the toner in the developing container 22 is provided. A toner supply path 24 connected to the toner container 4a (see FIG. 1) is connected to an upper portion of the toner supply port 23. The rotation shaft 43 b passes through the toner supply port 23 and extends into the toner supply path 24. At a portion of the rotation shaft 43 b disposed in the toner supply path 24, a supply blade 43 c spirally formed at a constant pitch in the axial direction of the rotation shaft 43 b is integrally formed. The supply blade 43c is formed by a spiral blade (in the same phase) that faces in the same direction as the first spiral blade 43a, and is formed to have a smaller pitch and a smaller diameter than the first spiral blade 43a.

  Here, the replenished toner replenished from the toner replenishing path 24 is deposited on the outermost layer of the developer present near the toner replenishing port 23 and floats. Therefore, there is a possibility that the replenishment toner to be replenished into the first conveyance chamber 22c through the toner replenishment path 24 and the toner replenishment port 23 may not be sufficiently stirred with the developer in the first conveyance chamber 22c. As a result, problems such as fogging of the image and toner scattering may occur due to charging failure of the toner. In addition, the accuracy in controlling the toner concentration (T / C) also occurs due to the poor dispersion of the replenishment toner in the developer.

  Therefore, in the present embodiment, the second spiral 44 disposed in the second transfer chamber 22 d is extended to the inside of the toner supply path 24, and development is performed at the boundary between the second transfer chamber 22 d and the toner supply path 24. There is provided a stirring regulation unit 44c that blocks the agent.

  The second spiral 44 disposed in the second transfer chamber 22d includes a rotation shaft 44b, a second spiral blade 44a integrally provided on the rotation shaft 44b, a stirring regulation portion 44c, and a third spiral blade 44d. Have. The second spiral blade 44a is formed in a spiral shape by blades (in the same phase) facing the same direction as the first spiral blade 43a. The rotation shaft 44 b is disposed in parallel to the rotation shaft 43 b and rotatably supported by the developing container 22. The second spiral blade 44 a rotates the counterclockwise direction in FIG. 2 to convey the developer in the second transfer chamber 22 d in the A2 direction (the direction opposite to the A1 direction) while conveying the developer to the developing roller 20. Supply.

  The stirring restricting portion 44c is formed by a spiral blade (in antiphase) facing in the opposite direction to the second spiral blade 44a. The agitation regulating unit 44c applies a transport force in the direction (A1 direction) opposite to the transport direction (A2 direction) to the developer in the second transport chamber 22d.

  The rotation shaft 44 b extends beyond the stirring regulation portion 44 c into the toner supply path 24. A third spiral blade 44 d is formed in a portion of the rotation shaft 44 b disposed in the toner supply path 24. The third spiral blade 44d is formed by a spiral blade (in the same phase) that faces in the same direction as the second spiral blade 44a, and is formed to have a smaller pitch and a smaller diameter than the second spiral blade 44a. There is.

  The second communication portion 22 f is formed at an end portion of the partition portion 22 b in the width direction (the arrow X direction in FIG. 2) of the developing container 22. More specifically, as shown in FIG. 2, the second communicating portion 22f is a side (right side in FIG. 2) of the partition 22b from which the developer is lifted by rotation of the second spiral 44 (counterclockwise direction in FIG. 2). Formed at the end of the Therefore, the developer stirring direction (from the bottom to the top) by the second spiral 44 near the second communication portion 22f and the falling direction of the developer falling from the second transfer chamber 22d to the first transfer chamber 22c (from above) The downward direction is reversed.

  On the other hand, since the first spiral 43 rotates in the opposite direction (clockwise direction in FIG. 2) to the second spiral 44, the developer stirring direction (from the top to the bottom) by the first spiral 43 near the second communication portion 22f. And the falling direction of the developer falling from the second transfer chamber 22d to the first transfer chamber 22c are the same.

  The second communication portion 22f is formed to have a width of 2 mm or more in the container width direction (the arrow X direction) in order to suppress the clogging of the developer. Although not shown here, the first communication portion 22e is formed at the center of the partition 22b in the container width direction.

  In the developing device 3a, as shown in FIG. 3, the developer in the first transfer chamber 22c is stirred and transferred by the first spiral 43 in the A1 direction (the first communicating portion 22e side), and the developer in the first transfer chamber 22c is It will gradually deposit on one side. On one side of the first transfer chamber 22c, the developer is pushed by the subsequent developer and pushed up to the second transfer chamber 22d via the first communication portion 22e.

  The developer in the second transfer chamber 22d is supplied to the developing roller 20 while being stirred and transferred by the second spiral 44 in the A2 direction (the second communication portion 22f side). The developer on the developing roller 20 which has not been used for development falls from the developing roller 20 at the same pole portion of the magnetic pole member 20b and is collected in the second transfer chamber 22d. Then, the developer is blocked by the application of the conveyance force in the reverse direction by the stirring regulation part 44c, and the developer is dropped into the first conveyance chamber 22c via the second communication part 22f.

  In the developing device 3a of the present embodiment, the second transfer chamber 22d is disposed above the first transfer chamber 22c. That is, the first transfer chamber 22c and the second transfer chamber 22d are arranged vertically. Thus, the developing device 3a can be miniaturized in the horizontal direction. Since the four developing devices 3a to 3d are arranged in the horizontal direction in the color printer 100, downsizing the developing devices 3a to 3d is particularly effective for downsizing the color printer 100.

  Further, in the present embodiment, the second communicating portion 22f in which the developer falls from the second transfer chamber 22d to the first transfer chamber 22c is the end of the partition 22b on the side where the developer is lifted by the rotation of the second spiral 44. It is formed in the part. As a result, the direction in which the developer is stirred by the second spiral 44 in the second transfer chamber 22 d is opposite to the direction in which the developer falling from the second transfer chamber 22 d to the first transfer chamber 22 c is reversed. The agent can be more thoroughly agitated.

  Further, the direction in which the developer is stirred by the rotation of the first spiral 43, and the direction in which the developer falling from the second transfer chamber 22d to the first transfer chamber 22c through the second communicating portion 22f is the same direction. As a result, the developer can be smoothly dropped into the first transfer chamber 22c.

  Furthermore, even when the flowability of the developer changes due to environmental conditions or the like, the transition of the developer in the second transfer chamber 22d can be stabilized. Specifically, in a situation where the amount of developer stagnant around the second communicating portion 22f is small, the developer transported to the downstream end of the second transfer chamber 22d is blocked by the stirring regulating portion 44c, and 2) Drop into the first transfer chamber 22c via the communication portion 22f. On the other hand, in a situation where the amount of developer stagnating around the second communication portion 22f increases, a part (remaining portion) of the developer transported to the downstream end of the second transfer chamber 22d passes over the stirring regulating portion 44c. It flows into the toner supply path 24. That is, the toner supply path 24 functions as a bypass conveyance path for the developer falling from the second conveyance chamber 22 d into the first conveyance chamber 22 c.

  Therefore, the amount of developer in the second transfer chamber 22d is stabilized, so that the developer is not uniformly supplied to the developing roller 20, and a stable image can be maintained for a long time. In addition, since the pressure acting on the developer at the downstream end of the second transfer chamber 22d in the developer transfer direction (direction A2) is reduced, the upstream side of the first transfer chamber 22c in the developer transfer direction (direction A1) The compression effect of the developer at the end is also reduced. As a result, it is possible to suppress the cohesion of the developer and an increase in the driving torque of the first spiral 43 associated therewith.

  FIG. 4 is a partial enlarged view of the periphery of the second communication portion 22 f in FIG. 3. As shown in FIG. 4, the developer passes through the edge 20b1 on the downstream side (the stirring regulation portion 44c side) of the magnetic pole member 20b in the developing roller 20 in the developer transport direction (A2 direction) of the second transport chamber 22d. Let L be a straight line orthogonal to the transport direction (A1, A2 direction). At this time, an edge 44c1 on the upstream side of the stirring regulation part 44c and an edge 22f1 on the upstream side of the second communication part 22f overlap on the straight line L with respect to the developer conveyance direction (A2 direction) of the second conveyance chamber 22d. It is placed in position.

  Here, the edge 20b1 of the magnetic pole member 20b in the developing roller 20 is an edge of a developable area capable of supplying the developer to the photosensitive drum 1a. Therefore, in order to reliably supply the developer to the developable area of the developing roller 20, the developer in the second transfer chamber 22d needs to be sufficiently present to a position facing the edge 20b1. Therefore, it is necessary to dispose the stirring restricting portion 44c at a position overlapping the edge 20b1 of the magnetic pole member 20b or at the downstream side of the edge 20b1 of the magnetic pole member 20b with respect to the developer conveyance direction of the second transfer chamber 22d. Similarly, it is necessary to arrange the second communication portion 22f at a position overlapping the end 20b1 of the magnetic pole member 20b or downstream of the end 20b1 of the magnetic pole member 20b with respect to the developer conveyance direction of the second transfer chamber 22d. .

  On the other hand, the second transfer chamber 22d and the first transfer chamber 22c are elongated as the stirring restricting portion 44c and the second communication portion 22f move away from the end 20b1 of the magnetic pole member 20b to the downstream side in the developer transfer direction (direction A2). It is necessary to extend in the direction, and the size of the developing device 3a is increased. Therefore, as in the present embodiment, the end 44c1 on the upstream side of the stirring restriction portion 44c and the end 22f1 on the upstream side of the second communication portion 22f in the developer transport direction of the second transfer chamber 22d are the magnet member 20b. By arranging at the position overlapping with the edge 20b1, the developer can be reliably supplied to the developable region of the developing roller 20, and the developing device 3a can be space-saving in the longitudinal direction.

  Further, the replenished toner replenished from the toner replenishing path 24 through the toner replenishing port 23 enters the first transfer chamber 22c along the rotation shaft 43b of the first spiral 43 (indicated by an alternate long and short dash line arrow in FIG. 4) ). Then, the developer in the first transfer chamber 22c (the developer dropped from the second transfer chamber 22d) is stirred and mixed to be charged to a predetermined charge amount.

  Further, the developer which has passed over the stirring regulation portion 44c from the second conveyance chamber 22d and entered the toner replenishment path 24 is agitated with the replenishment toner in the toner replenishment path 24 by the third spiral blade 44d. That is, the replenishment toner dropped from the toner container 9 into the toner replenishment path 24 is stirred together with the developer which has entered into the toner replenishment path 24 before entering the first transfer chamber 22c. Therefore, the replenishment toner and the developer in the developing container 22 can be sufficiently mixed and stirred, and fogging images and toner scattering can be effectively suppressed.

  FIG. 5 is a side sectional view showing the configuration of the developing device 3a according to the second embodiment of the present invention, and FIG. 6 is a longitudinal sectional view showing the structure of the stirring portion of the developing device 3a of the second embodiment (FIG. 5 is a sectional view taken along the line YY '). In the present embodiment, the second transfer chamber 22d is disposed obliquely above the first transfer chamber 22c. Further, the toner replenishment port 23 is formed at the end of the first transport chamber 22c on the upstream side of the developer transport direction, and the replenishment toner drops from above from the toner replenishment port 23 into the first transport chamber 22c. It has become. Therefore, the developer that has got over the stirring regulation portion 44 c flows into the bypass conveyance path 50. The configuration of the other parts of the developing device 3a is the same as that of the first embodiment.

  Also in the present embodiment, in a situation where the amount of developer remaining around the second communication portion 22f is small, the developer conveyed to the downstream end of the second transfer chamber 22d is blocked by the stirring regulation portion 44c, It falls into the first transfer chamber 22c via the second communication portion 22f. On the other hand, in a situation where the amount of developer stagnating around the second communication portion 22f increases, a part (remaining portion) of the developer transported to the downstream end of the second transfer chamber 22d passes over the stirring regulating portion 44c. It flows into the bypass conveyance path 50. Therefore, as in the first embodiment, even when the flowability of the developer changes due to environmental conditions or the like, the transition of the developer in the second transfer chamber 22d can be stabilized.

  Further, in the case where the replenishment toner falls from the upper side to the upstream side end in the developer conveyance direction in the first conveyance chamber 22c as in the present embodiment, the developer on the upstream side end of the first conveyance chamber 22c If the amount is large, the replenishment toner may be deposited on the upper surface of the developer and easily transported in a floating state, and the developer may not be sufficiently stirred with the developer in the first transport chamber 22c. As in the present embodiment, by providing the stirring regulation portion 44c and the bypass conveyance path 50 to reduce the developer amount at the upstream end of the first conveyance chamber 22c, the replenishment toner is introduced into the first conveyance chamber 22c from above. It is also effective in the falling configuration.

  Others The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in each of the above embodiments, an example is shown in which the developer is supplied from the second spiral 44 to the developing roller 20, but the present invention is not limited to this. A developer carrier such as a magnetic roller is further provided between the second spiral 44 and the developing roller 20, and the developer is supplied from the second spiral 44 to the magnetic roller and the like, and then the toner is supplied to the developing roller 20 from the magnetic roller and the like. It may be supplied.

  Further, the present invention is not limited to the tandem type color printer 100 shown in FIG. 1, but is disposed above the first transfer chamber and the first transfer chamber of digital or analog monochrome copiers, color copiers, facsimiles, etc. The present invention is applicable to various image forming apparatuses provided with a developing device including a second transfer chamber. Hereinafter, the effects of the present invention will be more specifically described by way of examples.

  Using the developing device 3a of the first embodiment shown in FIGS. 2 and 3, the circulation state of the developer in the developing container 22 and the mixability of the replenishment toner were investigated. About the circulation state of the developer, the presence or absence of the stagnation of the developer in the developing container 22 was visually confirmed while the developing device 3a was driven. The mixing property of the replenished toner was stopped after driving the developing device 3a while replenishing the toner from the toner replenishing port 23, and the state of the replenished toner inside the developing container 22 was visually confirmed.

  The developing roller 20 used for the developing device 3a uses a developing sleeve 20a with an outer diameter of 16 mm and a rotating member for supporting the developing sleeve 20a rotatably and having a magnetic pole member 20b with four magnetic poles fixed. It was rotated at 366 rpm. As the first spiral 43, as the first spiral blade 43a, a spiral blade having an outer diameter of 16 mm and a pitch of 30 mm is formed on the outer peripheral surface of the rotation shaft 43b. The second spiral 44 forms a double spiral blade with an outer diameter of 16 mm and a pitch of 30 mm on the outer peripheral surface of the rotation shaft 44b as a second spiral blade 44a, and a reverse spiral blade with an outer diameter of 16 mm and a pitch of 5 mm as a stirring regulation portion 44c. The one formed in the range of 450 ° was used. The first spiral 43 and the second spiral 44 were rotated at a rotation speed of 326 rpm.

  The second communicating portion 22f of the developing container 22 is opened 5 mm from the side edge (right end edge in FIG. 2) of the partitioning portion 22b with a dimension of 5 mm in the width direction (X direction) of the developing container 22 . Further, the dimension of the developer conveyance direction (A1, A2 direction) is 5 mm, and the downstream side end edge 20b1 of the magnetic pole member 20b with respect to the developer conveyance direction (A2 direction) of the second conveyance chamber 22d (right end edge in FIG. 4) And it opened for 5 mm from the upstream edge 44c1 of the stirring control part 44c to downstream.

  The developer is a two-component developer consisting of positively charged toner having an average particle diameter of 6.8 μm and ferrite carrier having an average particle diameter of 38 μm, and the ratio of carrier to toner (weight ratio, T / C) is 8 %. The amount of developer supplied to the developing device 3a was 150 g.

  As a result of the test, it was confirmed that the developer was flowing smoothly through the first transfer chamber 22c and the second transfer chamber 22d without stagnating the circulation of the developer in the vertical direction of the developing container 22. In addition, it is confirmed that there is no stagnation of the replenishment toner at the bottom of the development container 22 and no suspension of the replenishment toner on the surface layer of the developer, and that the mixing and stirring of the developer and the replenishment toner in the development container 22 is promoted. .

  The present invention is applicable to a developing device having a first transfer chamber and a second transfer chamber disposed above the first transfer chamber. By the use of the present invention, it is possible to stabilize the transition of the amount of developer in the developing container, and to provide a developing device capable of realizing miniaturization and an image forming apparatus provided with the same.

3a to 3d developing device 20 developing roller (developer carrier)
20a developing sleeve 20b magnet member 22 developing container 22b partition part 22c first transfer chamber 22d second transfer chamber 22e first communicating portion 22f second communicating portion 23 toner replenishment port 24 toner replenishment path (bypass conveyance path)
42 stirring and conveying member 43 first spiral (first stirring and conveying member)
44 2nd spiral (2nd stirring conveyance member)
44a 2nd spiral blade (conveying blade)
44b Rotor shaft 44c Stirring restriction section 44d Third spiral blade (sub transfer blade)
50 bypass conveyance path 100 color printer (image forming apparatus)

Claims (7)

A developing container containing a first transfer chamber, and a second transfer chamber disposed above the first transfer chamber with the partition portion interposed therebetween, and containing a two-component developer including a carrier and a toner;
A first stirring and conveying member rotatably supported in the first conveyance chamber and stirring and conveying the developer in the first conveyance chamber in a first direction;
The second conveyance chamber is rotatably supported in parallel with the first stirring conveyance member, and rotates in the opposite direction to the first stirring conveyance member to developer in the second conveyance chamber in the first direction. A second stirring and conveying member for stirring and conveying in a second direction opposite to the direction
A developer carrier which is rotatably supported by the developer container and carries the developer in the second transfer chamber on the surface thereof;
In the developing device provided with
The developing container includes a first communicating portion communicating downstream end portions of the first transfer chamber and the second transfer chamber in the first direction, the first transfer chamber, and the second transfer chamber. A second communication portion communicating downstream end portions in two directions, and a downstream side of the second direction with respect to the second communication portion, wherein the second transfer chamber and the second transfer chamber are provided And a bypass conveyance path communicating the downstream end portions of the
The second stirring and conveying member is formed on a rotating shaft, and an outer peripheral surface of the rotating shaft, and is configured to move and stir the developer in the second transfer chamber in the second direction, and to the second direction. And a stirring restricting portion configured to be adjacent to the downstream side of the transport blade and configured to transport the developer in the first direction;
The developing device is characterized in that the stirring regulation portion is disposed downstream of the second communication portion with respect to the second direction and upstream of the bypass conveyance path. The developer carrier has a developing sleeve rotatably supported by the developing container, and a magnetic pole member fixed non-rotatably in the developing sleeve.
The end on the upstream side of the stirring restriction portion with respect to the second direction, where L is a straight line passing through the downstream edge of the magnetic pole member with respect to the second direction and orthogonal to the first and second directions. 2. The developing device according to claim 1, wherein the edge and the upstream end edge of the second communication portion are disposed at a position overlapping on the straight line L, or downstream of the straight line L. 3.   3. The apparatus according to claim 2, wherein an upstream edge of the agitation restricting portion and an upstream edge of the second communication portion with respect to the second direction are disposed at positions overlapping the straight line L. The developing device as described. A toner supply port provided at an end of the first transfer chamber in the second direction and supplying toner into the first transfer chamber along a rotation axis of the first agitating transfer member;
A lower end portion of the bypass conveyance path communicates with the upper side of the toner supply port, and an upper end portion of the bypass conveyance path communicates with a toner storage container for storing the toner to be supplied to the developing container. The developing device according to any one of claims 1 to 3.   The second stirring and conveying member is formed adjacent to the downstream side of the stirring regulating portion with respect to the second direction, and conveys the developer in the same direction as the conveying blade to carry the developer in the bypass conveying path. The developing device according to any one of claims 1 to 4, further comprising a secondary conveyance blade for stirring and conveying.   The second communication portion is a side on which the developer moves upward from the bottom by rotation of the second stirring and conveying member in the width direction of the developing container orthogonal to the axial direction of the second stirring and conveying member, and The developing device according to any one of claims 1 to 5, wherein the developing device is formed at an end portion of the partition portion on the side where the developer moves downward from above by the rotation of a stirring and conveying member.   An image forming apparatus comprising the developing device according to any one of claims 1 to 6.

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