JP2022051114A - Developer conveying device with narrowed portion - Google Patents

Abstract

To prevent problems such as an image defect (fog) and toner scattering in a developer conveying device.SOLUTION: A developer conveying device includes: a housing; a channel 21, 22 extending inside the housing in a longitudinal direction; and a stirring and conveying member 23, 24 extending within the channel to convey a developer through a conveyance path 25, 26 formed between the channel and the stirring and conveying member. The conveyance path includes a main portion 26A extending along a substantial portion of the conveyance path, and a narrowed portion 26B formed outside the main portion. A first cross-sectional area of the conveyance path taken in the narrowed portion is less than a second cross-sectional area of the conveyance path taken in the main portion.SELECTED DRAWING: Figure 2

Description

A developing device that develops an electrostatic latent image of an image carrier using a developer containing toner and a carrier is known. Such a developing device is provided with a developer transporting device including a channel extending in the longitudinal direction and a stirring and transporting member extending in the channel. The developer is conveyed while being agitated by the agitating and conveying member in the conveying path formed between the channel and the agitating and conveying member.

FIG. 1 is a schematic cross-sectional view of an example developing apparatus that can be used to carry out the various examples disclosed herein. FIG. 2 is a schematic cross-sectional view of an example developer transfer device. FIG. 3 is a partially enlarged view of a schematic cross-sectional view shown in FIG. FIG. 4 is a schematic end-view view of the IV-IV line shown in FIG. FIG. 5 is a schematic end view taken along the line VV shown in FIG. FIG. 6 is a schematic cross-sectional view of the developer transfer device of the comparative example. FIG. 7 is a graph showing the charge distribution amount of Example 1 in which the drive time is 10 seconds. FIG. 8 is a graph showing the charge distribution amount of Example 1 in which the drive time is 15 seconds. FIG. 9 is a graph showing the charge distribution amount of Example 1 with the drive time set to 20 seconds. FIG. 10 is a graph showing the charge distribution amount of Example 1 with the drive time set to 30 seconds. FIG. 11 is a graph showing the charge distribution amount of Comparative Example 1 in which the drive time is 10 seconds. FIG. 12 is a graph showing the charge distribution amount of Comparative Example 1 in which the drive time is 15 seconds. FIG. 13 is a graph showing the charge distribution amount of Comparative Example 1 in which the drive time is 20 seconds. FIG. 14 is a graph showing the charge distribution amount of Comparative Example 1 in which the drive time is 30 seconds. FIG. 15 is a schematic cross-sectional view showing a part of the developer transfer device of another example. FIG. 16 is a schematic cross-sectional view showing a part of the developer transfer device of another example. FIG. 17 is a schematic cross-sectional view showing a part of the developer transfer device of another example. FIG. 18 is a schematic cross-sectional view showing a part of the developer transfer device of another example. FIG. 19 is a schematic cross-sectional view showing a part of the developer transfer device of another example. FIG. 20 is a schematic cross-sectional view showing a part of the developer transfer device of another example. FIG. 21 is a schematic cross-sectional view showing a part of the developer transfer device of another example. FIG. 22 is a schematic cross-sectional view showing a part of the developer transfer device of another example. FIG. 23 is a schematic cross-sectional view showing a part of the developer transfer device of another example.

In the developer transfer device provided in the developing device for developing the electrostatic latent image of the image carrier, the carrier of the magnetic material and the toner of the non-magnetic material are stirred and mixed, and the carrier and the toner are triboelectrically charged. When the toner concentration of the developing agent decreases, the replenishing toner is replenished, the replenishing toner and the developing agent are stirred and mixed, and the replenishing toner is triboelectrically charged with the developing agent. Here, if the size of the developing device is reduced or the amount of the developing agent is reduced, the amount of the developing agent that is agitated and mixed with the replenishing toner and is triboelectrically charged becomes small. For this reason, image defects (stain) that occur when the toner mass (soft blocking toner) contained in the replenishing toner is supplied onto the developing roller without collapsing, and the replenishing toner is developed without being sufficiently frictionally charged with the developer. Problems such as image defects (fog) caused by being supplied on the rollers and toner scattering caused by weak electrostatic adhesion between the carrier and toner due to insufficient frictional charging of the developer occur. It will be easier to do.

Therefore, for example, the transport path formed between the channel of the housing and the stirring transport member for transporting the developer is a main portion extending along most of the transport path and a constricted portion formed on the outside of the main portion. It is assumed that the first cross-sectional area of the transport path in the narrowed portion is smaller than the second cross-sectional area of the transport path in the main portion. As a result, the developer is agitated and conveyed along the transport path, but is temporarily accumulated on the upstream side of the stenosis and pushed into the stenosis, so that the developer is agitated and mixed and triboelectricly charged in the stenosis. Be promoted. As a result, even if the amount of the developer to be agitated and mixed with the replenishing toner is reduced by reducing the size of the developing device and the amount of the developing agent, it is possible to suppress the increase of image defects and toner scattering.

Hereinafter, an example developer transfer device will be described with reference to the drawings. In the description based on the drawings, the same elements or similar elements having the same functions are designated by the same reference numerals, and duplicate description will be omitted. Further, the value indicated by "abbreviation" includes the value and indicates a range including the vicinity of the value. Therefore, the value represented by "abbreviation" may be, for example, the value itself in which "abbreviation" is deleted.

FIG. 1 is a schematic cross-sectional view of an example of a developing device provided with an example of a developer transporting device. The developing apparatus 1 shown in FIG. 1 develops an electrostatic latent image formed on the surface (peripheral surface) of the image carrier 2 to form a toner image. The developing device 1 includes a housing 3, a developing roller 4, a developer transporting device 5, and a layer thickness regulating member 6. In the developing apparatus 1, a two-component developing agent containing a toner and a carrier is used as the developing agent. That is, in the developing apparatus 1, the toner and the carrier are adjusted to have a desired mixing ratio, and the toner is further mixed and stirred to disperse the toner, whereby the developer to which the optimum charge amount is applied is adjusted.

The housing 3 has a developing chamber 7 inside. The developing chamber 7 of the housing 3 contains a developing agent containing toner and a carrier. Further, the developing roller 4 and the layer thickness regulating member 6 are housed in the developing chamber 7 of the housing 3. The housing 3 has an opening adjacent to the developing roller 4, and the developer in the developing chamber 7 is supplied to the image carrier 2 from this opening.

The developing roller 4 is arranged so as to face the image carrier 2 so as to form a gap between the developing roller 4 and the image carrier 2, and the developer housed in the housing 3 is supported on the surface and rotated. That is, the developing roller 4 rotates in a predetermined direction to carry the developer. The developing roller 4 is formed in a columnar shape, for example. The developing roller 4 is arranged so that the rotating axis A1 of the developing roller 4 and the rotating axis A2 of the image carrier 2 are parallel to each other. The developing roller 4 carries the developing agent contained in the developing chamber 7 of the housing 3 on the surface. The developing roller 4 develops the electrostatic latent image of the image carrier 2 by transporting the supported developer to the developing region 8. The developing region 8 is a region located between the developing roller 4 and the image carrier 2, and is a region where the developing roller 4 and the image carrier 2 face each other.

The developing roller 4 includes a developing sleeve 11 that forms the surface layer of the developing roller 4, and a magnet 12 that is arranged inside the developing sleeve 11. The developing sleeve 11 is a tubular member made of a non-magnetic metal. The developing sleeve 11 is rotatable about the rotation axis A1. The magnet 12 is fixed to the shaft 13 on the rotation axis A1 fixed to the housing 3, for example, and has a plurality of magnetic poles. The developing sleeve 11 is rotatably supported by, for example, the shaft 13, and is rotationally driven by a drive source (not shown) such as a motor. The developer is supported on the surface of the developing sleeve 11 by the magnetic force of the magnet 12. The developing roller 4 conveys the developing agent in the rotation direction of the developing sleeve 11 by rotating the developing sleeve 11. The rotation of the developing roller 4 means that the developing sleeve 11 rotates, and the rotation direction of the developing roller 4 means the rotation direction of the developing sleeve 11.

On the developing sleeve 11, a magnetic brush of the developing agent is formed by the magnetic force of each magnetic pole of the magnet 12. The magnetic brush of the developer is also called the spike of the developer. In the developing region 8, the developing roller 4 brings the magnetic brush of the developer formed by the magnetic poles into contact with or close to the electrostatic latent image of the image carrier 2. As a result, the toner of the developer carried on the developing roller 4 moves to the electrostatic latent image formed on the peripheral surface of the image carrier 2, and the electrostatic latent image is developed.

The layer thickness regulating member 6 limits the thickness of the developer supported on the developing roller 4. That is, the layer thickness regulating member 6 limits the amount of the developer conveyed by the developing roller 4. The layer thickness regulating member 6 is arranged in the vicinity of the developing region 8 on the upstream side of the developing region 8 in the rotation direction of the developing roller 4. The layer thickness regulating member 6 forms a predetermined gap with the developing roller 4. Therefore, the layer thickness regulating member 6 limits the layer thickness of the developer supported on the peripheral surface of the developing roller 4 by rotating the developing roller 4. By adjusting the distance between the layer thickness regulating member 6 and the developing roller 4, the amount of the developing agent conveyed by the developing roller 4 conveyed to the developing region 8 can be adjusted.

The developer transport device 5 transports the developer contained in the developing chamber 7 of the housing 3 while stirring. That is, the developer transfer device 5 agitates the carrier of the magnetic material constituting the developer and the toner of the non-magnetic material, and causes the carrier and the toner to be triboelectrically charged. Further, the developer transport device 5 transports the developer while stirring.

FIG. 2 is a schematic cross-sectional view of an example developer transfer device. FIG. 3 is a partially enlarged view of the schematic cross-sectional view shown in FIG. As shown in FIGS. 1 to 3, the developer transfer device 5 is arranged below the developing roller 4 and is arranged adjacent to the first channel 21 and the first channel 21 extending in the longitudinal direction D in the housing 3. A second channel 22 extending in the longitudinal direction in the housing 3, a first stirring and transporting member 23 extending in the first channel 21, and a second stirring and transporting member 24 extending in the second channel 22. To prepare for. A first transport path 25 for transporting the developer is formed between the first channel 21 and the first stirring transfer member 23. A second transport path 26 for transporting the developer is formed between the second channel 22 and the second stirring transfer member 24. At one end of the first channel 21 and the second channel 22, a first through hole 27 for connecting the first transport path 25 and the second transport path 26 is formed. At the other end of the first channel 21 and the second channel 22, a second through hole 28 for connecting the first transport path 25 and the second transport path 26 is formed. That is, the first transport path 25 and the second transport path 26 communicate with each other through the first through hole 27 and the second through hole 28. Further, a replenishment port 29 for replenishing the replenishment toner is communicated with the second transport path 26. The supply port 29 is arranged on the opposite side of the first through hole 27 from the second through hole 28.

The first stirring and transporting member 23 and the second stirring and transporting member 24 stir the magnetic carrier constituting the developer and the non-magnetic toner, and cause the carrier and the toner to be triboelectrically charged. The first stirring and transporting member 23 extends into the first channel 21 and transports the developer through the first transport path 25. In the example of FIG. 2, the developer transport direction D1 in the first transport path 25 is to the right. The second stirring and transporting member 24 extends into the second channel 22 and transports the developer through the second transport path 26. In the example of FIG. 2, the developer transport direction D2 in the second transport path 26 is leftward.

The first stirring and transporting member 23 is a supply auger for stirring the developing agent and supplying the developing agent to the developing roller 4. The first stirring and transporting member 23 includes a rotary shaft 31 extending along the rotary axis A3, and a spiral blade 32 protruding from the rotary shaft 31 in the radial direction of the rotary shaft 31. The rotary shaft 31 is rotationally driven around the rotary axis A3 by a drive source (not shown) such as a motor. The spiral blade 32 extends spirally around the rotary shaft 31 so that the developer can be transported in the transport direction D1 when the rotary shaft 31 rotates. The developer of the first transport path 25 transported in the transport direction D1 by the first stirring and transport member 23 is supplied to the developing roller 4 and also to the second transport path 26 through the second through hole 28.

The second stirring transfer member 24 is an admix auger for stirring the developing agent and circulating the developing agent between the first transport path 25 and the second transport path 26. The second stirring and transporting member 24 includes a rotary shaft 33 extending along the rotary axis A4, and a spiral blade 34 protruding from the rotary shaft 33 in the radial direction of the rotary shaft 33. The rotary shaft 33 is rotationally driven around the rotary axis A4 by a drive source (not shown) such as a motor. The spiral blade 34 extends spirally around the rotary shaft 33 so that the developer can be transported in the transport direction D2 when the rotary shaft 33 rotates. The developer in the second transport path 26, which is transported in the transport direction D2 by the second stirring and transport member 24, is supplied to the first transport path 25 through the first through hole 27.

The second transport path 26 has a main portion 26A extending along most of the second transport path 26 and a constricted portion 26B formed on the outside of the main portion 26A. The first cross-sectional area of the second transport path 26 in the narrowed portion 26B is smaller than the second cross-sectional area of the second transport path 26 in the main portion 26A. The first cross-sectional area and the second cross-sectional area are cross-sectional areas along a plane orthogonal to the transport direction D2 of the developer in the second transport path 26. The first cross-sectional area of the second transport path 26 in the narrowed portion 26B may be, for example, 80% or less or 70% or less of the second cross-sectional area of the second transport path 26 in the main portion 26A. , 60% or less. Further, the first cross-sectional area of the second transport path 26 in the narrowed portion 26B may be, for example, 50% or more, or 60% or more, of the second cross-sectional area of the second transport path 26 in the main portion 26A. It may be 70% or more.

The second channel 22 has a protruding portion 30 projecting toward the second stirring and transporting member 24 in order to form the narrowed portion 26B. That is, the protruding portion 30 is a portion for making the first cross-sectional area of the second transport path 26 in the narrowed portion 26B smaller than the second cross-sectional area of the second transport path 26 in the main portion 26A. The protrusion 30 may be formed by the housing 3 itself forming the second channel 22, or may be formed by attaching another member to the housing 3 forming the second channel 22. The protruding portion 30 is located, for example, on the upstream side of the straight line portion 30A in the transport direction D2 and the straight line portion 30A having an inner surface parallel to the rotation axis A4, and the distance between the straight line portion 30 and the rotation axis A along the transport direction D2 is large. The first tapered portion 30B that gradually becomes closer, and the second tapered portion 30C that is located on the downstream side of the straight line portion 30A in the transport direction D2 and gradually increases in distance from the rotation axis A along the transport direction D2. Has.

FIG. 4 is a schematic end-view view of the IV-IV line shown in FIG. FIG. 5 is a schematic end view taken along the line VV shown in FIG. As shown in FIGS. 3-5, the second channel 22 has a gutter-shaped wall 22A that opens upward. The opening of the second channel 22 upward does not mean that there is nothing above the second channel 22, but that the lower end of the second stirring and transporting member 24 and the second channel 22 are above the second stirring and transporting member 24. It means that a space larger than the gap between the two channels 22 is formed. The cross section of the wall 22A along the plane orthogonal to the transport direction D2 in the second transport path 26 is formed, for example, in a U shape open upward.

The second channel 22 has a roof portion 22B extending to the high flow portion 26C of the second transport path 26 to form a tunnel in the high flow portion 26C. The roof portion 22B narrows the space formed above the second stirring and transporting member 24 as compared with the portion where the roof portion 22B is not formed. The roof portion 22B forms, for example, a gap having substantially the same size as the gap between the lower end of the second stirring and transporting member 24 and the second channel 22 around the second stirring and transporting member 24. The cross section of the roof portion 22B along the plane orthogonal to the transport direction D2 in the second transport path 26 is formed, for example, in an arc shape having the same diameter as the lower end portion of the second channel 22.

As shown in FIGS. 1 to 3, the second stirring transfer member 24 has a first portion 24A adjacent to the upstream side of the narrowed portion 26B of the second transport path 26 in the transport direction D2 and a narrowed portion of the second transport path 26. It has a second portion 24B, which extends along 26B.

In the first portion 24A, the spiral blade 34 is formed, and a high flow portion 26C that promotes the movement of the developer is formed in the main portion 26A of the second transport path 26. The high flow portion 26C is a portion of the second transport path 26 adjacent to the upstream side of the narrowed portion 26B in the transport direction D2. The first portion 24A is provided with, for example, an additional spiral blade 35 in addition to the spiral blade 34 in order to promote the movement of the developer. The additional spiral blade 35, apart from the spiral blade 34, protrudes from the rotary shaft 33 in the radial direction of the rotary shaft 33. Further, the additional spiral blade 35, like the spiral blade 34, extends spirally around the rotary shaft 33 so that the developer can be transported in the transport direction D2 when the rotary shaft 33 rotates. The additional spiral blade 35 may not be provided other than the first portion 24A.

The second portion 24B is not formed with the spiral blade 34, but is formed with a protruding portion 36 projecting toward the second channel 22 in order to form the narrowed portion 26B. That is, the protruding portion 36 is a portion for making the first cross-sectional area of the second transport path 26 in the narrowed portion 26B smaller than the second cross-sectional area of the second transport path 26 in the main portion 26A. The protruding portion 36 is a portion where the diameter of the rotating shaft 33 is expanded. The protrusion 36 may be formed by the rotating shaft 33 itself, or may be formed by attaching another member to the rotating shaft 33. The protrusion 36 is located, for example, on the upstream side of the straight line portion 36A having an outer peripheral surface parallel to the rotation axis A4 and the straight line portion 36A in the transport direction D2, and the distance between the straight line portion 36 and the rotation axis A along the transport direction D2 is large. It has a tapered portion 36B that gradually becomes farther away. A spiral groove 37 is formed on the outer peripheral surface of the straight portion 36A. The spiral groove 37 extends spirally on the outer peripheral surface of the straight line portion 36A so that the developer can be conveyed in the conveying direction D2 when the rotating shaft 33 rotates.

In the developer transfer device 5 configured as described above, when the rotary shaft 31 of the first stirring transfer member 23 is rotationally driven by the drive device (not shown), the developer rotates integrally with the rotary shaft 31. It is conveyed in the transfer direction D1 while being agitated by the spiral blade 32. Then, the developer is supplied to the developing roller 4 and is supplied from the first transport path 25 to the second transport path 26 through the second through hole 28.

Further, when the rotary shaft 33 of the second stirring and transporting member 24 is rotationally driven by a drive device (not shown), the developer is stirred and mixed by the spiral blade 34 that rotates integrally with the rotary shaft 33, and is also mixed. While being triboelectrically charged, it is transported in the transport direction D2. When the replenishment toner is replenished from the replenishment port 29 due to a decrease in the toner concentration of the developer or the like, the replenishment toner is agitated and mixed with the developer and is transported in the transport direction D2 while being triboelectrically charged with the developer. Toner.

Here, in the narrowed portion 26B, since the second transport path 26 is narrowed by the protruding portion 30 of the second channel 22 and the protruding portion 36 of the second stirring transport member 24, the upstream of the narrowed portion 26B in the transport direction D2. In the high flow portion 26C adjacent to the side, a developer pool in which the developer temporarily accumulates is generated. The developer temporarily accumulated in the high flow portion 26C is pushed into the narrowed portion 26B by the spiral blade 34 and the additional spiral blade 35 formed in the second portion 24B of the second stirring and transporting member 24. At this time, since the tunnel is formed in the high flow portion 26C by the roof portion 22B of the second channel 22, the developer temporarily accumulated in the high flow portion 26C is efficiently pushed into the narrowed portion 26B.

The developer pushed into the narrowed portion 26B is sufficiently stirred and mixed between the protruding portion 30 of the second channel 22 and the protruding portion 36 of the second stirring and transporting member 24, and is sufficiently triboelectrically charged. It is discharged from the narrowed portion 26B. Further, the developer pushed into the narrowed portion 26B enters the spiral groove 37 formed in the protruding portion 36 of the second stirring and transporting member 24, so that the contact area with the second stirring and transporting member 24 increases and friction occurs. Charging is promoted, and at the same time, transportation in the transport direction D2 is promoted. Then, the developer discharged from the narrowed portion 26B is supplied from the second transport path 26 to the first transport path 25 through the first through hole 27 in a state of being sufficiently stirred and mixed and sufficiently triboelectrically charged. .. In this way, in the developer transfer device 5, the first transfer path 25 and the second transfer path 26 are circulated.

Here, the charge distribution amount of the developer was measured using the developing devices of Example 1 and Comparative Example 1. As Example 1, a developing device 1 provided with the developing agent transporting device 5 shown in FIG. 2 was used. As Comparative Example 1, a developing device provided with the developing agent transfer device 100 shown in FIG. 6 was used. In the developer transfer device 100 shown in FIG. 6, the narrowed portion 26B is not provided in the second transport path 26, the protruding portion 30 is not provided in the second channel 22, and the developer transfer device 100 is added to the second stirring transfer member 24. The same applies to the developer transfer device 5 shown in FIG. 2, except that the spiral blade 35 and the protrusion 36 are not provided. In the measurement of the charge distribution amount of the developer over time, after supplying a small amount of additional toner to the developing device and driving it for a predetermined time, the developing device is stopped and the developing agent on the developing roller is sampled, and this sampling is performed. The amount of charge distribution of the developed developer was measured. The drive time of the developing device was set to 10 seconds, 15 seconds, 20 seconds, and 30 seconds. An E-SPART analyzer manufactured by Hosokawa Micron Corporation was used to measure the charge distribution amount.

FIG. 7 is a graph showing the charge distribution amount of Example 1 in which the drive time is 10 seconds. FIG. 8 is a graph showing the charge distribution amount of Example 1 in which the drive time is 15 seconds. FIG. 9 is a graph showing the charge distribution amount of Example 1 with the drive time set to 20 seconds. FIG. 10 is a graph showing the charge distribution amount of Example 1 with the drive time set to 30 seconds. FIG. 11 is a graph showing the charge distribution amount of Comparative Example 1 in which the drive time is 10 seconds. FIG. 12 is a graph showing the charge distribution amount of Comparative Example 1 in which the drive time is 15 seconds. FIG. 13 is a graph showing the charge distribution amount of Comparative Example 1 in which the drive time is 20 seconds. FIG. 14 is a graph showing the charge distribution amount of Comparative Example 1 in which the drive time is 30 seconds. In FIGS. 7 to 14, the horizontal axis shows the charge amount distribution (q / d), and the vertical axis shows the number of sample developers.

As shown in FIGS. 11 to 14, in Comparative Example 1, when 15 seconds have passed since the additional toner was replenished (see FIG. 12), the charge amount distribution greatly expanded, and then the charge amount distribution became the original with the passage of time. It returned to the state of. This is because the charge distribution was stable until the replenished additional toner was supplied to the developing roller (see FIG. 11), but it was a while after the replenished additional toner was supplied to the developing roller. During this period, the additional toner was not sufficiently stirred and mixed and triboelectricly charged, so it is considered that the charge amount distribution was greatly expanded (see FIG. 12). After that, it is considered that the charge amount distribution became stable because the additional toner was sufficiently stirred and mixed with the developer and triboelectrically charged with the passage of time (see FIGS. 13 and 14).

On the other hand, as shown in FIGS. 7 to 10, in Example 1, the charge amount distribution was stable regardless of the passage of time after the additional toner was replenished. It is considered that this is because the replenished additional toner was immediately stirred and mixed and triboelectrically charged, so that the spread of the charge amount distribution as in Comparative Example 1 was suppressed.

As described above, in the developer transport device 5, the developer is agitated and transported along the second transport path 26, but is temporarily accumulated in the high flow portion 26C adjacent to the upstream side of the narrowed portion 26B. Since it is pushed into the narrowed portion 26B, stirring and mixing of the developer and triboelectric charging are promoted in the narrowed portion 26B. As a result, by downsizing the developing apparatus 1 and reducing the amount of the developing agent, it is possible to suppress an increase in image defects and toner scattering even if the amount of the developing agent to be agitated and mixed with the replenishing toner is reduced. For example, an image defect (stain) caused by the toner lump contained in the replenishing toner being supplied onto the developing roller without collapsing, and the replenishing toner being supplied onto the developing roller without being sufficiently triboelectrically charged with the developer. It is possible to prevent problems such as image defects (fog) caused by this and toner scattering caused by weak electrostatic adhesion between the carrier and toner due to insufficient triboelectric charging of the developer. ..

It should be understood that all aspects, advantages and features described herein are not necessarily achieved or included by any one particular example and embodiment. In fact, although various examples have been described and shown herein, it should be clear that other examples can be modified in their arrangement and details. All modifications and modifications contained within the spirit and scope of the protected subject matter claimed herein are claimed.

For example, as shown in FIG. 15, the second stirring and transporting member 24 has a plurality of additional spiral blades 35A in the high flow portion 26C of the second transporting path 26 (in the first portion 24A of the second stirring and transporting member 24). May have. This makes it possible to further promote stirring and mixing of the developer and triboelectric charging. In this case, the blade thickness of the additional spiral blade 35A may be thinner than the blade thickness of the spiral blade 34 from the viewpoint of further promoting stirring and mixing of the developer and triboelectric charging.

Further, as shown in FIG. 16, when the portion of the spiral blade 34 in the high flow portion 26C of the second transport path 26 is a high flow spiral blade 34A, the spiral blade 34 is a spiral blade 34 other than the high flow spiral blade 34A. The pitch of the high flow spiral blade 34A may be smaller than the pitch of the high flow spiral blade 34A. This makes it possible to further promote stirring and mixing of the developer and triboelectric charging. In this case, the blade thickness of the high-flow spiral blade 34A may be thinner than the blade thickness of the spiral blades 34 other than the high-flow spiral blade 34A from the viewpoint of increasing the carrying power of the developer. Further, the additional spiral blade 35 may be provided, or the additional spiral blade 35 may not be provided.

Further, as shown in FIG. 17, a textured protrusion 30a may be formed on the surface of the protrusion 30, and as shown in FIG. 18, a groove 30b orthogonal to the transport direction D2 is formed on the surface of the protrusion 30. Alternatively, as shown in FIG. 19, a groove 30c parallel to the transport direction D2 may be formed on the surface of the protrusion 30. As a result, the frictional force between the protruding portion 30 of the second channel 22 and the developer in the narrowed portion 26B can be increased.

Further, as shown in FIG. 20, the unevenness 36a may be formed on the protruding portion 36 of the second stirring and transporting member 24. As a result, the frictional force between the protruding portion 36 of the second stirring and transporting member 24 and the developing agent in the narrowed portion 26B can be increased. The size, number, orientation, etc. of the unevenness 36a can be appropriately set.

Further, if the first cross-sectional area of the second transport path 26 in the narrowed portion 26B is smaller than the second cross-sectional area of the second transport path 26 in the main portion 26A, as shown in FIG. 21, the second stirring transport member 24 It is not necessary to have the protrusion 36, and as shown in FIG. 22, the second channel 22 may not have the protrusion 36. In the case shown in FIG. 21, the amount of protrusion of the protruding portion 30 toward the second stirring and transporting member 24 is increased from the viewpoint of further improving the transport performance of the developer, the stirring and mixing performance, and the triboelectric charging performance in the narrowed portion 26B. Therefore, the first cross-sectional area of the second transport path 26 in the narrowed portion 26B may be reduced. Similarly, in the case shown in FIG. 22, the amount of protrusion of the protrusion 36 toward the second channel 22 is increased from the viewpoint of further improving the transport performance, stirring and mixing performance, and triboelectric charging performance of the developer in the narrowed portion 26B. , The first cross-sectional area of the second transport path 26 in the narrowed portion 26B may be reduced.

Further, as shown in FIG. 23, the spiral groove 37 may not be formed in the protruding portion 36 of the second stirring and transporting member 24.

Further, in the above example, it has been described that two transport paths, the first transport path 25 and the second transport path 26, are provided as the transport path for the developer, but one transport path for the developer is provided. A transport path may be provided, or three or more transport paths may be provided. When a plurality of transport paths are provided as the transport paths for the developer, the first cross-sectional area of the transport path in the narrowed portion is smaller than the second cross-sectional area of the transport path in the main portion in any of the transport paths. In a plurality of transport paths, the first cross-sectional area of the transport path in the narrowed portion may be smaller than the second cross-sectional area of the transport path in the main portion.

Claims (15)

With the housing
A channel extending in the longitudinal direction in the housing and
A stirring and transporting member extending in the channel and transporting the developer through a transport path formed between the channel and the channel.
The transport path has a main portion extending along most of the transport path and a constricted portion formed on the outside of the main portion.
The first cross-sectional area of the transport path in the constricted portion is smaller than the second cross-sectional area of the transport path in the main portion.
Developer transfer device. The channel has a protrusion that projects toward the stirring and transporting member to form the constriction.
The developer transfer device according to claim 1. The agitation transport member has a protrusion that protrudes toward the channel in order to form the constriction.
The developer transfer device according to claim 1. The stirring and transporting member has a rotating shaft extending along a rotation axis and a spiral blade protruding radially from the rotating shaft.
The stirring and transporting member is
The first portion adjacent to the upstream side of the narrowed portion of the transport path in the transport direction of the developer, and the first portion on which the spiral blade is formed.
A second portion extending along the constricted portion of the transport path, the second portion having no spiral vane and having a spiral groove.
The developer transfer device according to claim 1. The stirring and transporting member has a rotating shaft extending along a rotation axis and a spiral blade protruding radially from the rotating shaft.
The transport path has a high flow portion adjacent to the upstream side of the constricted portion of the transport path in the transport direction of the developer.
The developer transfer device according to claim 1. The agitated transfer member has one or more additional spiral vanes formed around the rotary shaft in the high flow portion of the transfer path.
The developer transfer device according to claim 5. The spiral blades are formed so that the pitch in the high flow portion of the transport path is smaller than the pitch of the spiral blades other than the high flow portion of the transport path.
The developer transfer device according to claim 5. The stirring and transporting member does not have the spiral blade in the narrowed portion.
The developer transfer device according to claim 5. The rotation axis of the stirring and transporting member has a spiral groove in the narrowed portion.
The developer transfer device according to claim 5. The rotating shaft of the stirring and transporting member has a protrusion forming the narrowed portion.
The protrusion has the spiral groove.
The developer transfer device according to claim 9. The blade thickness of the spiral blade is thinner in the high flow portion of the transport path than in the main portion of the transport path.
The developer transfer device according to claim 5. The channel has a gutter-shaped wall that opens upwards and has a gutter-shaped wall.
The channel has a roof portion extending to the high flow portion of the transport path to form a tunnel in the high flow portion.
The developer transfer device according to claim 5. The first cross-sectional area and the second cross-sectional area are cross-sectional areas along a plane orthogonal to the transport direction of the developer.
The developer transfer device according to claim 1. The first cross-sectional area of the transport path is 80% or less of the second cross-sectional area of the transport path.
The developer transfer device according to claim 1. With the housing
A channel extending longitudinally in the housing and
A stirring and transporting member extending in the channel and transporting the developer through a transport path formed between the channel and the channel.
A constriction is formed along the transport path,
The first cross-sectional area of the transport path in the narrowed portion is smaller than the second cross-sectional area of the transport path on the downstream side of the narrowed portion in the transport direction of the developer.
Developer transfer device.

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