JP2021086043A - Developing device - Google Patents

Abstract

To achieve both a transportation performance and an agitation performance of developers.SOLUTION: A second transportation screw 65 is disposed in an agitation chamber 63 and comprises a rotation shaft and a plurality of strips of blade parts 91, 92, and 93 being formed spirally around the rotation shaft and transporting developers with its rotation in a rotation direction R1 to a second direction D2 in a longitudinal direction X. Among the plurality of strips of blade parts 91, 92, and 93, at least one strip of blade part 93 has a gap part 94 that makes the blade part 93 discontinuous in at least a part of an installation region from a downstream end of a supply port to an upstream end of detection means with respect to the second direction D2, and a rib 95 provided so as to be continuous toward the upstream side of the second direction D2 from a downstream side end 93a of the blade part 93 where the downstream side end 93a in the rotation direction R1 faces the gap part 94 and have a gap 96 with the blade part 92 located adjacent on the upstream side with respect to the second direction D2 and different from the blade part 93.SELECTED DRAWING: Figure 8

Description

The present invention relates to a developing device applied to an image forming device such as a copier, a printer, a facsimile, and a multifunction device having a plurality of these functions.

In electrophotographic image forming devices, especially in image forming devices that form full-color or multi-color images, many developing devices mainly contain non-magnetic toner and magnetic carriers from the viewpoint of image tint. A component developer is used. In the case of a developing apparatus using a two-component developing agent, the developing agent contained in the developing container is conveyed while being stirred by a screw. As a screw that conveys the developer while stirring in this way, two spirally formed blades are provided around the rotating shaft, and each of the two blades is discontinuous in the axial direction of the rotating shaft. A configuration has been proposed in which a discontinuity portion is provided (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2010-256429

However, in the configuration described in Patent Document 1 described above, since discontinuous portions are provided in each of the two blade portions, there is a possibility that the transportability of the developer cannot be sufficiently ensured. That is, the discontinuous portions provided in each of the two blade portions are formed so as to cut out the respective blades with the same volume, only the phases are different from each other. Therefore, although improvement in the agitation property of the developer can be expected, the discontinuous portion in the blade portion reduces the area of the blade portion that contributes to the transport of the developer, so that the transportability of the developer is lowered. Resulting in. With the configuration described in Patent Document 1, since the transportability of the developer is lowered in any of the blades, there is a possibility that the transportability of the developer as a screw cannot be sufficiently ensured.

An object of the present invention is to provide a developing apparatus capable of achieving both transportability and stirring property of a developer.

The developing apparatus of the present invention forms a developing agent-bearing body that carries and carries the developing agent, a first chamber that supplies the developing agent to the developing agent-bearing body, and a circulation path between the first chamber and the developing agent. A developing container having a second chamber, a first transport member disposed in the first chamber and transporting the developer in the first direction by rotation, and a developing container disposed in the second chamber. On the other hand, a rotatably provided rotating shaft and a spirally formed around the rotating shaft are formed, and the developer is conveyed in the second direction opposite to the first direction in the direction of the rotating axis by rotation in the rotating direction. A second transport member having a plurality of blades, a replenishment port for replenishing the developer from a replenishment means capable of replenishing the developing container, and a second chamber provided in the second chamber. (2) A developing apparatus including a detecting means for detecting information on the toner concentration of a developer in a room, wherein at least one first blade of the plurality of blades is in the second direction. In at least a part of the installation area between the downstream end of the supply port and the upstream end of the detection means, the gap portion in which the first blade portion is discontinuous and the downstream end portion in the rotational direction are said. It is different from the first blade portion which is continuous from the downstream end portion of the first blade portion facing the gap portion to the upstream side in the second direction and is located adjacent to the upstream side in the second direction. It is characterized in that it has a rib provided with a gap between it and the second blade portion.

According to the present invention, it is possible to achieve both the transportability of the developer and the stirring property.

It is sectional drawing which shows the image forming apparatus which concerns on this embodiment. It is sectional drawing of the developing apparatus which concerns on this embodiment. It is a vertical sectional view of the developing apparatus which concerns on this embodiment. It is a side view of the 2nd transport screw which concerns on this embodiment. It is a graph which shows the relationship between the blade angle and the outer peripheral length in the 2nd transport screw which concerns on this embodiment. It is a graph which shows the length and the phase of the gap part of the blade part of the 2nd transport screw which concerns on this embodiment. It is a side view of the 2nd transport screw which concerns on this embodiment, (a) is a state which is seen from the outer peripheral surface of a rib, (b) is a state which is seen from the V direction of (a). It is a side view of the 2nd transport screw which concerns on this embodiment, (a) is a state in which a developer has fallen into a gap, and (b) is a state in which a part of the dropped developer is scooped up by a rib. It is a graph which shows the relationship between the developer amount and the developer amount ratio of each 2nd transport screw which concerns on Example and comparative example. It is a graph which shows the relationship between the amount of the developer and the concentration difference of each 2nd transport screw which concerns on Example and Comparative Example. It is a side view of the 2nd transport screw which concerns on a comparative example. It is a side view of the 2nd transport screw which concerns on a comparative example, (a) is a state where a developer has fallen into a void part, and (b) is a state where the dropped developer has been diverted. It is a side view when the developer is a small amount in the 2nd transport screw which concerns on a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 10. First, the schematic configuration of the image forming apparatus of this embodiment will be described with reference to FIG.

[Image forming device]
The image forming apparatus 1 of the present embodiment is an electrophotographic tandem full-color printer provided with four image forming units PY, PM, PC, and PK each having a photosensitive drum 3 as an image carrier. The image forming apparatus 1 uses a toner image (image) as a recording material in response to an image signal from a host device such as a personal computer communicably connected to the document reading apparatus 2 provided on the upper portion or the image forming apparatus 1. Form. Examples of the recording material include sheet materials such as paper, plastic film, and cloth (hereinafter, abbreviated as sheets). Further, the image forming portions PY, PM, PC, and PK form toner images of yellow, magenta, cyan, and black, respectively.

The four image forming units PY, PM, PC, and PK included in the image forming apparatus 1 have substantially the same configuration except that the developed colors are different. Therefore, here, the image forming unit PY will be described as a representative, and the description of other image forming units will be omitted.

The image forming apparatus 1 includes a control unit 12. The control unit 12 includes a CPU, a ROM that stores a program that controls each unit, a RAM that temporarily stores data, and an input / output circuit that inputs / outputs signals to and from the outside. The CPU is a microprocessor that controls the entire control of the image forming apparatus 1, and is the main body of the system controller. The CPU is connected to a sheet feeding unit, an image forming unit PY, PM, PC, PK, a sheet conveying unit, etc. via an input / output circuit, and exchanges signals with each unit and controls operations.

[Image forming part]
The image forming unit PY includes a photosensitive drum 3, a charging roller 4, an exposure device 5, a developing device 6, a primary transfer roller 7, and a cleaning blade 8. The photosensitive drum 3 and the charging roller 4 are rotatably supported by the drum container 51, and the charging roller 4 and the cleaning blade 8 are supported in a state of being pressed against the photosensitive drum 3. The photosensitive drum 3, the charging roller 4, the cleaning blade 8, and the drum container 51 form a drum cartridge 50, and are removable from the apparatus main body 10.

As the rotatable image carrier, the photosensitive drum 3 is a cylindrical (drum type) electrophotographic photosensitive member having a photosensitive layer which is an organic optical semiconductor having negative charging characteristics. The photosensitive drum 3 has a diameter of 30 mm and a length in the longitudinal direction of 360 mm, is driven and connected to a drive source (not shown) built in the apparatus main body 10, and has a process speed (peripheral speed) of 250 mm / sec. It rotates by the driving force.

The charging roller 4 has, for example, a diameter of 14 mm and a length of 320 mm in the longitudinal direction, and since it is pressed by the photosensitive drum 3, it rotates in accordance with the photosensitive drum 3. The charging roller 4 is urged toward the photosensitive drum 3 by an urging spring (not shown). Further, the photosensitive drum 3 is uniformly charged by applying a charging bias (DC voltage: −900V, AC peak-to-peak voltage: 1500V) to the charging roller 4 from a high-voltage power supply as an application means. As the exposure apparatus 5, a laser beam scanner provided with a semiconductor laser that irradiates a photosensitive drum 3 charged by a charging roller 4 with a laser beam is applied.

A transfer device 20 is arranged above each image forming unit PY, PM, PC, and PK. The transfer device 20 is configured such that an endless intermediate transfer belt 21 is stretched on a plurality of rollers and orbits (rotates) in the direction of an arrow. Then, the intermediate transfer belt 21 carries and conveys the toner image that has been primarily transferred to the intermediate transfer belt 21. The secondary transfer outer roller 23 is arranged at a position where the secondary transfer inner roller 22 and the intermediate transfer belt 21 are opposed to each other among the rollers on which the intermediate transfer belt 21 is stretched, and the toner image on the intermediate transfer belt 21 is arranged. Consists of a secondary transfer unit T2 that transfers the sheet S to the sheet S. A fixing device 30 is arranged downstream of the secondary transfer unit T2 in the sheet transport direction. Above the transfer device 20, a storage container 9 for replenishing the developing device 6 with a developing agent for replenishment is arranged.

A cassette 40 containing the sheet S is arranged below the image forming apparatus 1. The sheet S fed from the cassette 40 is conveyed toward the registration roller 42 by the transfer roller 41. Then, the tip of the sheet S abuts against the registration roller 42 in the stopped state, and a loop is formed to correct the skew of the sheet S. After that, the registration roller 42 starts rotating in synchronization with the toner image on the intermediate transfer belt 21, and the sheet S is conveyed to the secondary transfer unit T2.

The process of forming, for example, a four-color full-color image by the image forming apparatus 1 configured as described above will be described. First, when the image forming operation is started, the surface of the rotating photosensitive drum 3 is uniformly charged by the charging roller 4. Next, the photosensitive drum 3 is exposed by a laser beam corresponding to the image signal emitted from the exposure apparatus 5, and an electrostatic image corresponding to the image signal is formed on the photosensitive drum 3. The electrostatic image on the photosensitive drum 3 is visualized by the toner as a developing agent contained in the developing device 6 and becomes a visible image.

The toner image formed on the photosensitive drum 3 is formed on the intermediate transfer belt 21 by the primary transfer unit T1 (see FIG. 2) formed between the toner image and the primary transfer roller 7 arranged so as to sandwich the intermediate transfer belt 21. Primary transcription. At this time, a primary transfer bias is applied to the primary transfer roller 7. The transfer residual toner remaining on the surface of the photosensitive drum 3 after the primary transfer is removed by the cleaning blade 8.

Such an operation is sequentially performed by the yellow, magenta, cyan, and black image forming portions PY, PM, PC, and PK, and the toner images of four colors are superimposed on the intermediate transfer belt 21. After that, the sheet S housed in the cassette 40 is conveyed to the secondary transfer unit T2 at the timing of forming the toner image. Then, by applying the secondary transfer bias to the secondary transfer outer roller 23, the four-color toner images on the intermediate transfer belt 21 are collectively secondary-transferred onto the sheet S. The toner that cannot be completely transferred by the secondary transfer unit T2 and remains on the intermediate transfer belt 21 is removed by the intermediate transfer belt cleaner 24.

Next, the sheet S is conveyed to the fixing device 30. The fixing device 30 includes a fixing roller 31 and a pressure roller 32 having a heat source such as a halogen heater inside, and the fixing roller 31 and the pressure roller 32 form a fixing nip portion. The sheet S is heated and pressurized by passing the sheet S on which the toner image is transferred through the fixing nip portion of the fixing device 30. Then, the toner on the sheet S is melted and mixed, and fixed on the sheet S as a full-color image. After that, the sheet S is discharged to the discharge tray 11 by the discharge roller 43. This completes a series of image formation processes.

The image forming apparatus 1 of the present embodiment forms a monochromatic or multicolor image by using an image forming unit for some of desired monochromatic or four colors, such as a black monochromatic image. Is also possible.

[Developer]
Next, the detailed configuration of the developing device 6 will be described with reference to FIGS. 2 and 3. In the present embodiment, the developing device 6 constitutes a developing cartridge in the form of a cartridge. The developing apparatus 6 includes a developing container 60 containing a developing agent containing a non-magnetic toner and a carrier having magnetism, and a developing sleeve (development) which is a cylindrical rotating body that carries and conveys the developing agent in the developing container 60. Agent carrier) 70 and. The developing sleeve 70 is housed in the developing container 60 with a gap G between the photosensitive drum 3 and carries the developing agent contained in the developing container 60, and conveys the developing agent to the developing region Ar1 facing the photosensitive drum 3. It is possible to develop an electrostatic latent image.

As shown in FIG. 3, the developing sleeve 70 has a central shaft 71, is supported by a sleeve bearing 72 that rotatably supports the central shaft 71 with respect to the developing container 60, and is rotationally driven in the direction of the arrow in FIG. To. As shown in FIG. 2, inside the developing sleeve 70, a magnet roller 73 as a developing magnet having a plurality of magnetic poles arranged in the circumferential direction is arranged non-rotatingly with respect to the developing container 60 by a magnet support shaft 74. ing. The inside of the developing container 60 is horizontally left and right in the developing chamber (first chamber) 62 and the stirring chamber (second chamber) 63 by a partition wall 61 whose substantially central portion extends in the direction of the rotation axis of the developing sleeve 70. It is partitioned. As a result, the developer is housed in the developing chamber 62 and the stirring chamber 63 separated by the partition wall 61. The developing chamber 62 and the stirring chamber 63 form a circulation path for the developer. A first transfer screw 64 as a first transfer member is arranged in the developing chamber 62, and a second transfer screw 65 as a second transfer member is arranged in the stirring chamber 63. The first transfer screw 64 and the second transfer screw 65 are arranged substantially in parallel along the rotation axis direction of the developing sleeve 70. In the present specification, the rotation axis direction of the second transport screw 65 is shown as the longitudinal direction (width direction) X, the back side of the apparatus main body 10 in the longitudinal direction X is shown as the first direction D1, and the front side is shown as the second direction D2. .. That is, the first direction D1 is the developer transport direction in the developing chamber 62, and the second direction D2 is the developer transport direction in the stirring chamber 63.

At both ends (left side and right side in FIG. 3) of the partition wall 61 in the longitudinal direction X, a first communication port 61a and a second communication port that allow the passage of the developer between the developing chamber 62 and the stirring chamber 63 are allowed. 61b is provided. The first transfer screw 64 and the second transfer screw 65 circulate in the developing chamber 62 and the stirring chamber 63 via the first communication port 61a and the second communication port 61b while stirring and transporting the developer in the developing container 60. Let me.

The first transfer screw 64 and the second transfer screw 65 are both screw-shaped members, and each has a spiral blade around a rotation axis. The first transfer screw 64 is arranged at the bottom of the developing chamber 62 along the longitudinal direction X of the developing sleeve 70, and the developer in the developing chamber 62 is agitated by rotating the rotating shaft with a drive source (not shown). While transporting the developer in the first direction D1, the developer is supplied to the developing sleeve 70. The developer supported on the developing sleeve 70 and whose toner is consumed in the developing step is collected in the developing chamber 62.

The second transport screw 65 is arranged at the bottom of the stirring chamber 63 along the longitudinal direction X of the developing sleeve 70, and the developer in the stirring chamber 63 is placed in the second direction D2 in the direction opposite to that of the first transport screw 64. To make the toner concentration uniform. Further, the partition wall 61 is provided at the first communication port 61a for passing the developer from the stirring chamber 63 to the developing room 62 and on the upstream side of the second communication port 61a from the developing room 62 to the developing room 63. Has a second communication port 61b for delivering the developing agent to. The developer is conveyed by the first transfer screw 64 and the second transfer screw 65, passes through the first communication port 61a and the second communication port 61b, and circulates in the developing container 60.

At the upstream end of the second transport screw 65 of the stirring chamber 63 in the second direction D2, a developer supply port (replenishment port) 66 for replenishing the developer containing toner is provided in the developing container 60. .. The developer replenishment port 66 is connected to a storage container 9 (see FIG. 1) as a replenishment means capable of replenishing the developing container 60 with a developer via a developer replenisher (not shown). Therefore, the replenishing developer is supplied from the storage container 9 into the stirring chamber 63 via the developing agent replenishing device and the developing agent replenishing port 66. The second transfer screw 65 conveys the developer supplied from the developer supply port 66 and the developer already in the stirring chamber 63 while stirring to make the toner concentration uniform.

Therefore, as shown in FIG. 3, the developing agent in the developing chamber 62 in which the toner is consumed in the developing process and the toner concentration is lowered due to the conveying force of the first conveying screw 64 and the second conveying screw 65 is in the first direction. It moves into the stirring chamber 63 through the second communication port 61b on the D1 side. Then, the developer that has moved into the stirring chamber 63 is conveyed while being stirred with the replenished developer, and moves to the developing chamber 62 via the first communication port 61a on the second direction D2 side.

As shown in FIG. 2, in the developing chamber 62 of the developing container 60, there is an opening 60a at a position corresponding to the developing region Ar1 facing the photosensitive drum 3, and in this opening 60a, the developing sleeve 70 is formed on the photosensitive drum 3. It is rotatably arranged so as to be partially exposed in the direction. Such a developing sleeve 70 is rotationally driven by a drive source, can convey the developing agent to the developing region Ar1, and supplies the developing agent to the photosensitive drum 3 in the developing region Ar1. In the present embodiment, the developing sleeve 70 is formed in a cylindrical shape by, for example, aluminum or stainless steel as a non-magnetic material, has a diameter of 20 mm, a length in the longitudinal direction of 334 mm, and has a process speed (peripheral speed) of 250 mm / sec. Rotates during development operation.

A developing blade 67 that regulates the amount (layer thickness) of the developing agent supported on the developing sleeve 70 is fixed on the upstream side of the opening 60a in the rotational direction of the developing sleeve 70. The developing blade 67 forms a thin layer of the developing agent on the surface of the developing sleeve 70. In the present embodiment, since the developing sleeve 70 rotates from the lower side in the gravity direction to the upper side in the developing region Ar1, the developing blade 67 is located below the developing region Ar1 in the gravity direction.

The magnet roller 73 has a total of five poles of a plurality of magnetic poles S1, S2, S3, N1 and N2 in the circumferential direction, and is formed in a roller shape. Such a magnet roller 73 generates a magnetic field for carrying the developer on the developing sleeve 70, and also generates a magnetic field for peeling the developer from the developing sleeve 70 in the peeling region.

The developer on the developing sleeve 70 forms magnetic spikes in the developing region Ar1 by rotating the developing sleeve 70. The magnetic ears come into contact with the photosensitive drum 3 rotating in the same direction as the developing sleeve 70 in the developing region Ar1, and the electrostatic image on the photosensitive drum 3 is developed as a toner image by the charged toner. Further, in order to improve the development efficiency, that is, the rate of applying toner to the latent image, a development bias voltage in which a DC voltage and an AC voltage are superimposed is usually applied to the development sleeve 70 from the development bias power supply. The developer on the developing sleeve 70 after the toner is supplied to the photosensitive drum 3 is recovered in the developing chamber 62 by further rotating the developing sleeve 70.

As shown in FIG. 3, the stirring chamber 63 of the developing container 60 is provided with an inductance sensor (detecting means) 68 for detecting information on the toner concentration of the developer in the stirring chamber 63 (second chamber). There is. In the present embodiment, the inductance sensor 68 is provided on the downstream side of the second direction D2 of the stirring chamber 63.

Further, in the present embodiment, the magnetic carriers are replenished together with the toner by mixing a small amount of carriers with the replenishing toner in the toner cartridge. On the other hand, by providing a discharge port (not shown) at one end of the developing container 60 for discharging the developer surplus due to the replenishment of the carriers from the developing device 6, the deteriorated carriers are discharged from the developing device 6. The carriers in the developing container 60 are replaced.

[Developer]
Here, the two-component developer used in the present embodiment will be described. As the developer, a mixture of a non-magnetic toner having a negative charge polarity and a magnetic carrier having a positive charge polarity is used. The non-magnetic toner is a resin in which a colorant, a wax component, etc. are encapsulated in a resin such as polyester or styrene acrylic, and powdered by crushing or polymerization, and fine powder such as titanium oxide or silica is added to the surface. .. The magnetic carrier is obtained by applying a resin coating to the surface layer of a core made of resin particles obtained by kneading ferrite particles or magnetic powder. The concentration of toner in the developer in the initial state is, for example, 8% to 10%.

[Regarding the agitation and transportability of the developer]
Next, the stirring property and the transportability of the developer by the second transport screw 65 that transports the developer in the stirring chamber 63 will be described. Since the replenishing developer is replenished in the stirring chamber 63 as described above, the second transfer screw 65 is required to have both the stirring property and the transporting property of the developer.

First, the agitation property will be described. In order to more faithfully develop the electrostatic latent image formed on the photosensitive drum 3 with toner, it is desired to stabilize the charge amount of the toner in the developing container 60. The amount of charge in the toner tends to depend on the toner concentration of the developer. That is, if the toner concentration of the developer is too high, the amount of charge of the toner becomes low, and if the toner concentration of the developer is too low, the toner is excessively charged. The larger the charged amount of toner, the smaller the amount of toner developed with respect to the latent image on the photosensitive drum 3, so if the charged amount of toner is uneven, the density unevenness will occur in the toner image on the photosensitive drum 3. It ends up.

Further, since the toner is charged by rubbing against the carrier, if the toner concentration of the developer is locally high in the developing container 60, the coating ratio of the toner on the carrier becomes too high, and the amount of charge of the toner becomes insufficient. Toner. As a result, toner is scattered to the non-image portion on the photosensitive drum 3, and toner is scattered to the outside of the developing container 60.

Further, when the bulk of the developer becomes high due to an increase in the amount of charge of the toner or the like, it becomes difficult for the supplementary developer to be taken into the radius of gyration of the transport screws 64 and 65. Therefore, the replenishing developer is conveyed while sliding on the developing agent already existing in the developing container 60, reaches the developing chamber 62 without being well agitated, and is pumped up by the developing sleeve 70. It can happen.

Here, the toner concentration of the developer immediately after the replenishment developer is replenished is high, whereas the toner concentration of the developer consumed by the developing sleeve 70 and recovered in the developing container 60 is low. .. Therefore, it is necessary to rapidly stir and mix the developer having different toner concentrations in this way to stabilize the toner concentration of the developer in the developing container 60.

Next, the transportability of the developer will be described. In order to supply the developing sleeve 70 with the same amount of toner as the toner consumption proportional to the output image density, it is desired to keep the transport speed of the developer at a predetermined level or higher by the transport screws 64 and 65. If the transport speed of the developer is slow, the time it takes for the replenished developer to reach the developing sleeve 70 is slow. Then, the toner density of the developer pumped up by the developing sleeve 70 decreases, and the image density gradually decreases. Therefore, it is desired that the transport speed of the developer by the transport screws 64 and 65 is secured at a predetermined speed or more, and the replenished developer is quickly reached at the developing sleeve 70. As described above, in the second transport screw 65 that transports the developer immediately after replenishment, it is desired to ensure both the agitation property of the developer and the transportability.

In particular, when continuously outputting an image having a high image ratio, which is a ratio of forming a toner image in an image-forming region, for example, a solid image having an image ratio of 100%, the amount of toner consumed per number of images to be imaged. The situation will continue. Therefore, it is necessary to perform a replenishment operation of supplying replenishment toner to the developing container 60 according to the amount of toner consumed. In such a situation where toner consumption and replenishment are continuous in a relatively short period of time, the toner concentration in the developing container 60 tends to become unstable, and if the stirring property and the transportability are not compatible, the density unevenness tends to occur. turn into.

Further, when the developing apparatus 6 is miniaturized and the amount of the developing agent contained in the developing container 60 is reduced, it becomes difficult to secure both the transportability of the developing agent and the stirring property. For example, when the developing apparatus 6 is miniaturized, it is conceivable to reduce the diameters of the transport screws 64 and 65. However, in this case, the area for pushing the developer by the blades of the transport screws 64 and 65 is reduced, so that the transport screw 64 and 65 are transported. The transportability of screws 64 and 65 tends to decrease.

On the other hand, in order to improve the transportability of the developer, it is conceivable that the blades of the transport screws 64 and 65 are multi-rowed. However, if the transport efficiency of the transport screws 64 and 65 is increased, most of the developer between the blades is transported without being well agitated. Further, this phenomenon becomes more remarkable when the amount of the developer in the developing container 60 decreases, the stirring property decreases, and the amount of charge of the toner in the developing container 60 becomes uneven.

On the other hand, the blades of each transport screw are multi-rowed, and for the second transport screw 165, the blades 193 are discontinuous with at least one blade 193 of the plurality of blades. It is conceivable to form a gap portion 194. Hereinafter, the second transfer screw 165 and the gap portion 194 will be described in detail with reference to FIGS. 11 to 13. FIG. 11 is a view of the second transport screw 165 viewed from the horizontal direction, and FIGS. 12 and 13 are sectional views in the vertical direction in the stirring chamber 63.

[Second transport screw of comparative example]
As shown in FIG. 11, the second transport screw 165 as a comparative example includes a rotating shaft 190 and a plurality of blade portions 191, 192, and 193 spirally formed around the rotating shaft 190. .. Here, the second transport screw 165 is a three-row screw having three blade portions 191 and 192, 193. Of the plurality of blade portions 191 and 192, 193, the two blade portions 191 and 192 have a shape continuous with respect to the longitudinal direction X of the rotating shaft 190.

On the other hand, the one blade portion 193, which is different from the two blade portions 191 and 192, has a shape having a gap portion 194 in which the blade portion 193 is discontinuous at at least a part of the longitudinal direction X of the rotating shaft 190. That is, a part of the blade portion 193 is deleted, and this portion is used as the gap portion 194. The three blades 191 and 192, 193 are formed in the order of the blade 191 and the blade 192 and the blade 193 from the upstream of the second direction D2 of the second transport screw 165, respectively, with the same outer diameter and the same pitch. Has been done.

Here, the behavior of the developer will be described by paying attention to the developer 292 conveyed by the blade portion 192 and the developer 293 conveyed by the blade portion 193. First, the developer 292 and the developer 293 are sequentially transported in the transport direction D3 by the portions of the blade portion 192 and the blade portion 193 that are continuously formed in a spiral shape. When the developing agent 293 reaches the gap portion 194, the flow of the developing agent 293 is divided into the transport direction D3 and the stirring direction D4 intersecting the transport direction D3 due to the presence of the gap portion 194.

That is, as shown in FIG. 12A, when the developer 293 (see FIG. 11) conveyed by the blade portion 193 reaches the gap portion 194, the developer 293a and the developer 293b are separated. The developer 293a falls due to its own weight and moves to the blade portion 192. The developer 293b exceeds the gap portion 194 and stays at the blade portion 193 due to inertia in the transport direction D3. The developer 293a transferred to the blade portion 192 is mixed with a part of the developer 292 carried by the blade portion 192.

Then, as shown in FIG. 12B, the second transport screw 165 continuously rotates. The mixed developer 292 and the developer 293a are the developer 292b and the developer 293b transported by the blade portion 193 following the gap portion 194 and the developer remaining in the blade portion 192 as the second transport screw 165 rotates. It is divided into 292a and a developer 293a. As a result, the developer independently conveyed by each of the three blades 191, 192, and 193 is agitated beyond the screw blades. In addition, in FIG. 12A and FIG. 12B, the developer 292 and the developer 293 are separated in order to clarify the movement of each developer conveyed by the blade portions 191 and 192, 193. Although illustrated, this does not represent the actual mixed state.

Here, the stirring property is most efficient when the developer 292 and the developer 293 are evenly mixed. That is, when the developer weights of the developer 292a and the developer 293a are equal. The weight ratio of the developer 292a to the developer 292 is Wa, and the weight ratio of the developer 293b to the developer 293b is Wb. At this time, it is desirable that Wa (1-Wa) / Wb (1-Wb) = 1 and 0.7 <Wa (1-Wa) / Wb (1-Wb) <1.3.

Further, among the three blade portions 191, 192, and 193, the blade portion 193 divides the flow of the developer, so that the transport speed of the developer is locally reduced. However, the remaining two blade portions 191 and 192 can secure the carrying power of the developer. Therefore, the transport speed of the second transport screw 165 as a whole is hardly reduced as compared with the screw having the same number of threads without the gap 194.

By the way, the surface of the developer in the developing container 60 fluctuates in the process of repeating the image forming operation in the image forming apparatus 1. This is due to changes in bulk density due to changes in the amount of charge carried by the developer, scattering to the outside of the developing container 60, and excessive and insufficient discharge of the developer due to replacement due to replenishment of the developer. This is due to fluctuations in the dosage itself. The comparative example and the present embodiment are designed on the premise that the amount of the developing agent varies from 120 g to 200 g. At this time, as shown in FIG. 13, especially when the amount of the developer is reduced and the surface of the developer is lowered, there is a possibility that the flow split into the transport direction D3 and the stirring direction D4, which is the effect of the gap 194, is not sufficiently performed. There is. That is, when the developer surface is lowered, the amount of the developer 293 (see FIG. 11) that stays in the blade portion 193 as the developer 293b decreases because the developer 293 (see FIG. 11) exceeds the gap portion 194 due to inertia.

Further, the mixed developer 292 and the developer 293a are less likely to be separated by the blade portion 193 following the gap portion 194. As a result, the developer 293b is reduced and the amount of the developing agent in the stirring direction D4 is increased without splitting in the transport direction D3. Therefore, the developer 292 is relatively increased as compared with the developer 293 as the agent distribution of the developer in the stirring chamber 63 after passing through the void portion 194.

As a result, the developer cannot be exchanged between the blade portion 191 and the blade portion 193, and stirring beyond the screw blades cannot be performed, and the stirring property of the second transfer screw 165 is lowered. Further, the amount of the developer conveyed by the blade portion 191 is relatively larger than that of the blade portion 192 and the blade portion 193, and the balance of the developer in the entire stirring chamber 63 is lost. That is, when the amount of the developer decreases, the ratio of the amount of the developer between the developer 292 and the developer 293 (the amount of the developer 293 / the amount of the developer 292) becomes smaller (see the comparative example of FIG. 9).

This instability of the developer balance may cause uneven density of the output image as described above. On the other hand, it is conceivable to reduce the space portion 194 to reduce the developer 293a that moves from the blade portion 193 to the stirring direction D4, but this is a developer that stays on the blade portion 193 when the developer surface is sufficient. Also increases, and the developer 293a transferred to the blade portion 192 decreases. Therefore, in the configuration in which the gap portion 194 is made smaller, the mixing ratio of the developer between the blade portion 192 and the blade portion 193 is reduced, and the stirring property is lowered. As described above, even if the amount of the developing agent fluctuates, it is desired to achieve both the transportability of the developing agent and the stirring property.

[Second transport screw of the present embodiment]
Therefore, in the present embodiment, the rib 95 is provided at the end of the blade portion 93 facing the upstream side of the rotation direction R1 of the gap portion 94 in order to cope with the fluctuation of the amount of the developer. Hereinafter, the second transfer screw 65 provided with the rib 95 will be described in detail with reference to FIGS. 4 to 8.

As shown in FIG. 4, the second transport screw 65 includes a rotating shaft 90 and blade portions 91, 92, and 93 having a plurality of rows formed spirally around the rotating shaft 90. In the present embodiment, the second transport screw 65 is a three-row screw having three blade portions 91, 92, 93. Of the plurality of blades 91, 92, 93, the two blades 91, 92 have a shape continuous with respect to the longitudinal direction X of the rotating shaft 90, and do not have a gap.

On the other hand, the one blade portion 93 as the first blade portion different from the two blade portions 91 and 92 has a gap portion 94 in which the blade portion 93 is discontinuous in at least a part of the longitudinal direction X of the rotating shaft 90. It is a shape having. That is, a part of the blade portion 93 is deleted, and this portion is used as the gap portion 94. The three blades 91, 92, and 93 are formed in the order of the blade 91, the blade 92, and the blade 93 from the upstream of the second direction D2 of the second transport screw 65, respectively, with the same outer diameter and the same pitch. Has been done.

Here, as shown in FIG. 5, for example, the length of the outer circumference of a circle having the outer diameter of the blade portion 93 as the diameter (the outer circumference length of the screw) is taken as the vertical axis, and one pitch of the blade portion 93 is taken as the horizontal axis. In this case, the angle formed by the diagonal line and the horizontal axis is defined as the angle θ of the blade portion 93. The outer diameter of the blade portion 93 is the outer diameter of the second transport screw 65, and is a circle whose radius is the distance from the center of the rotating shaft 90 to the outer circumference of the blade portion 93 in a cross section orthogonal to the rotating shaft 90. Corresponds to the outer diameter. In this case, the angle θ of the blade portion 93 is set to 56.5 ° or less. In particular, the angle θ of the blade portion 93 is preferably 39 ° or more and 56.5 ° or less, and more preferably 50 ° or more and 56.5 ° or less.

The outer diameter of the second transport screw 65 is preferably 12 mm or more and 20 mm or less, and more preferably 14 mm or more and 17 mm or less. For example, the outer diameter of the blade portion 93 of the second transport screw 65 is 14 mm, and the pitch is 30 mm. In the present embodiment, the angle θ of the blade portion 93 is set to 55.7 °. The same applies to the other blade portions 91 and 92.

According to the study of the present inventor, in the multi-thread screw, by setting the angle θ of the blade portion to 56.5 ° or less, it contributes to both ensuring the transportability of the developer and ensuring the stirring property. It has been found. That is, if the angle θ of the blade portion is too large, the screw pitch is small with respect to the outer peripheral length of the screw, so that the amount of the developer conveyed is reduced. Further, if the angle θ of the blade portion is too large and the screw pitch is small, the lead angle α (see FIG. 4) of the transport surface of the blade portion also becomes large, and the stirring property of the developer by the blade portion deteriorates. Therefore, in the present embodiment, the angle θ of the blade portion is set to 56.5 ° or less.

On the other hand, if the angle θ of the blade portion is too small, the screw pitch becomes large with respect to the outer peripheral length of the screw, so that the amount of the developer conveyed is reduced. Therefore, the angle θ of the blade portion is preferably 39 ° or more, more preferably 50 ° or more.

The first transfer screw 64 and the second transfer screw 65 have, for example, a pitch of 30 mm, a screw outer diameter of 14 mm, and a rotation shaft diameter of 6 mm. However, the diameter of the rotating shaft of the first transport screw 64 may be slightly larger than the rotating shaft of the second transport screw 65 (for example, 8 mm).

Further, FIG. 6 is a schematic representation of the second transport screw 65, focusing only on the blade portion 93. The quadrangle of the outer frame represents the phase. The thick solid line indicates the portion of the blade portion 93, and the thick dotted line indicates the gap portion 94. As shown in the figure, the blade portions 93 are formed so that a portion of the blade portions 93 and a gap portion 94 appear at intervals of 90 °. Therefore, in the present embodiment, for example, two gaps 94 are provided in one pitch. Further, when the portion of the blade portion 93 is viewed from the rotation axis direction for one round, the blade portion 93 and the gap portion 94 alternately exist for the same phase and overlap in the axial direction. Further, the ratio of the areas of the blade portion 93 and the gap portion 94 projected in the axial direction for one round of the blade portion 93 is 1: 1. In the present embodiment, the case where the blade portion 93 is formed so as to appear every 90 ° and the gap portion 94 appears, but the present invention is not limited to this, and for example, every 60 ° or every 45 °. May be good. In either case, the blade portion 93 and the gap portion 94 overlap when the portion of the blade portion 93 is viewed from the direction of the rotation axis for one round. The blade portion 93 is formed so that a region having a plurality of gap portions 94 in one pitch exists at at least one location in the installation region Ar2.

Further, in the present embodiment, in the second transport screw 65, the volume of one of the blade portions 93 in the longitudinal direction X of the second transport screw 65 is the blade portion 91 (or the blade) in the longitudinal direction X of the second transport screw 65. It is configured so as to be 75% or less of the volume of Article 1 of Part 92). In other words, if the blade portion 93 has a continuous shape along the rotation axis direction, the volume of the blade portion 93 is 75% or less of the volume of the blade portion having this shape. Further, when the volume of the gap portion 94 is assumed to be the volume of the virtual blade portion formed in the gap portion 94 assuming that the blade portion 93 has a continuous shape, the volume of the gap portion 94 is the gap portion. It is 25% or more of the total volume of 94 and the blade portion 93. That is, the volume ratio obtained by dividing the volume of the gap portion 94 in the entire area of the second transport screw 65 in the longitudinal direction X by the volumes of the blade portion 93 and the gap portion 94 in the entire area in the axial direction is 25% or more. I have to. The volume of the blade portion 93 and the gap portion 94 referred to here is the total volume of the second transport screw 65 in the longitudinal direction X. Therefore, the volume of the blade portion of the second transport screw 65 includes the blade portion of the return screw provided on the downstream side of the second transport screw 65 and the development provided on the upstream side of the second transport screw 65 and replenished. It does not include the volume of the blade portion of the screw that conveys the agent into the stirring chamber 63.

Further, the number of gaps 94 and ribs 95 in the blade 93 of the second transport screw 65 can be appropriately set according to the design conditions. Further, the rib 95 is not limited to being formed in all the gaps 94, and at least one gap 94 in which the rib 95 is formed is sufficient, and the gap 94 in which the rib 95 is not formed is sufficient. There may be.

[rib]
Next, the rib 95 provided on the second transport screw 65 will be described in detail with reference to FIGS. 4 and 7 (a) and 7 (b). FIG. 4 is a view of the second transport screw 65 viewed from the horizontal direction, FIG. 7 (a) is a view of the second transport screw 65 viewed from the outer peripheral surface of the rib 95, and FIG. 7 (b) is a view of the second transport screw. 65 is a view of 65 as viewed from the V direction of FIG. 7A.

As shown in FIG. 4, the rib 95 is in the second direction from the downstream end portion 93a of the rotation direction R1 of the blade portion 93 facing the upstream side in the rotation direction R1 and the downstream side in the second direction D2 from the gap portion 94. It is continuously provided toward the upstream side of D2. That is, the rib 95 is continuously provided from the downstream end portion 93a of the blade portion 93 whose downstream end portion in the rotation direction R1 faces the gap portion 94 to the upstream side in the second direction D2. The rib 95 is connected to the upstream portion of the front end of the gap portion 94 of the blade portion 93, is a rear portion in the developer transport direction, and is arranged in a direction extending in the axial direction of the second transport screw 65. The rib 95 is provided with a gap 96 between the rib 95 and the blade portion 92 as the second blade portion located adjacent to the upstream side in the second direction D2.

The rib 95 has a flat plate shape and has a shape extending radially in the outer diameter direction about the rotation shaft 90 of the second transport screw 65. The gap 94 and the rib 95 are provided in at least a part of the installation area Ar2 (see FIG. 3) between the downstream end of the developer supply port 66 and the upstream end of the inductance sensor 68 in the second direction D2. There is. This is because if the replenishing developer supplied to the developing container 60 reaches the detection region of the inductance sensor 68 without being sufficiently agitated with the developing agent contained in the developing container 60, the toner concentration is erroneously detected. Because there is a possibility. That is, there is a possibility that the developer in the developing container 60 may be detected as having an excess of toner than the original toner concentration due to the localization of the replenishing toner in the developer. In that case, the accuracy of the toner concentration control of the developer is lowered and the density fluctuation of the output image is expanded. Therefore, by installing the gap portion 94 and the rib 95 in the installation area Ar2 as in the present embodiment, the output is performed. The expansion of image density fluctuations is suppressed in advance.

Next, the installation angle of the rib 95 will be described with reference to FIG. 7A. The installation angle of the rib 95 is an arbitrary angle from the angle parallel to the rotating shaft 90 of the second transport screw 65 to the lead angle α of the blade portion 93, and is parallel to the rotating shaft 90 of the second transport screw 65. Is desirable. That is, the first virtual line VL1 along the rotation axis C is set from the downstream end portion 93a of the blade portion 93. Further, a second virtual line VL2 is set from the downstream end portion 93a of the blade portion 93 toward the gap portion 94. In this case, the second virtual line VL2 defines the pitch angle α of the blade portion 93 with respect to the first virtual line VL1. Then, the rib 95 is provided within the range from the first virtual line VL1 to the second virtual line VL2. In the present embodiment, the rib 95 is provided at an angle parallel to the rotation shaft 90 of the second transport screw 65, that is, on the first virtual line VL1. As a result, it is possible to achieve both agitation and transportability of the developer in a well-balanced manner.

In the present embodiment, the case where the rib 95 is provided on the first virtual line VL1 has been described, but the present invention is not limited to this. As described above, the rib 95 may be provided within the range from the first virtual line VL1 to the second virtual line VL2, and can be appropriately set according to other conditions such as dimensions and rotation speed. .. Further, in the present embodiment, the downstream end portion 93a of the blade portion 93 means the tip on the downstream side, but the present invention is not limited to this, and the position is slightly shifted to the upstream side in the rotation direction from the tip. May be good.

In the present embodiment, the pitch of each blade portion 91, 92, 93 is 30 mm. Therefore, the axial length L1 of the rib 95 (see FIG. 7B) is set to 5 mm. The outer diameter of each of the blade portions 91, 92, and 93 is 14 mm. Therefore, the length of the rib 95 in the normal direction is 14 mm from the center of the screw shaft. In the present embodiment, the case where the blade portion 93 has the same 30 mm pitch as the other blade portions 91 and 92 has been described, but the present invention is not limited to this. For example, the blade portion 93 may have a pitch different from that of the blade portions 91, 92 as long as it is within the region sandwiched between the blade portion 92 and the blade portion 91.

Further, as shown in FIG. 7B, from the V direction (circumferential direction) of FIG. 7A, the surface passing through the point where the rib 95 of the second transport screw 65 and the blade portion 93 are connected is observed. .. At this time, the ratio of the first area Sa1 formed by the rib 95 to the second area Sa2 obtained by removing the first area Sa1 of the rib 95 from the cross section between the blade portion 93 having the gap portion 94 and the blade portion 92 is Sa1: Sa2. Is preferably 1: 0.7 to 1: 1.3. This ratio is particularly preferably 1: 1 for Sa1: Sa2, and is 1: 1 in this embodiment. That is, as shown in FIG. 7 (b), when the rib 95 and the gap 96 are viewed from the V direction (circumferential direction) of FIG. 7 (a) at the arrangement position of the rib 95 and the gap 96, the area of the rib 95 is measured. The first area Sa1 is defined, and the area of the gap 96 is defined as the second area Sa2. The second area Sa2 is calculated based on the distance L2 between the rib 95 and the blade portion 92 in the longitudinal direction X and the height H of the blade portion 92 from the rotation shaft 90. In this case, the rib 95 is provided so that the second area Sa2 has an area 0.7 to 1.3 times that of the first area Sa1. In the present embodiment, the rib 95 is provided so that the second area Sa2 is the same as the first area Sa1. This is because the developer 292 and the developer 293a mixed between the blades 92 and 93 are uniformly transported by the blades 92 and 93 for the best transfer efficiency.

Further, since the first area Sa1 and the second area Sa2 are the same and the height H is constant, the length L2 of the gap 96 in the longitudinal direction X is the length of the rib 95 in the longitudinal direction X. It is provided so as to be 0.7 to 1.3 times as much as L1. In the present embodiment, the length L2 is provided so as to be the same as the length L1.

In the present embodiment, the rib 95 is provided so as to have the same outer diameter as the outer diameter of the blade portion 93. However, the rib 95 is not limited to having the same outer diameter as the outer diameter of the blade portion 93, and may be provided so as to have an outer diameter equal to or less than the outer diameter of the blade portion 93. For example, even when the rib 95 has an outer diameter smaller than the outer diameter of the blade portion 93, it is desirable to provide the rib 95 so that the second area Sa2 has an area 0.7 to 1.3 times that of the first area Sa1. .. However, in this case, since the heights of the first area Sa1 and the second area Sa2 are different, the length L2 of the gap 96 in the longitudinal direction X is 0.7 to 0.7 with respect to the length L1 of the rib 95 in the longitudinal direction X. It is not always 1.3 times. Further, if the rib 95 is lower than the outer diameter of the blade portion 93, a part of the developer may get over the outer peripheral side of the rib 95, so that the length X in the longitudinal direction of the rib 95 may be lengthened. preferable.

[Operation of the second transport screw]
Next, the operation when the second transport screw 65 is rotated to transport the toner in the second direction D2 will be described in detail with reference to FIGS. 8A and 8B. Here, a case where the amount of the developer is reduced and the surface of the developer is lowered will be described. As shown in FIG. 8A, the developer 293 carried by the blade portion 93 falls by its own weight when it approaches the gap portion 94. At this time, the developing agent 293a moving in the stirring direction D4 toward the blade portion 92 and the developing agent 293b moving in the transport direction D3 toward the blade portion 93 are separated. In the developer 293b, a part of the developer 293 that has fallen toward the blade portion 92 is blocked by the rib 95, and the developer is diverted toward the blade portion 93 instead of the blade portion 92.

When the developer surface is low, even if the developer conveyed between the screw pitches is localized near the wall surface of the blade portion 92, the amount of the developer conveyed in the stirring direction D4 is regulated by the rib 95 and is predetermined. The developer exceeding the amount of is forcibly sent to the blade portion 93. Therefore, the developer 293b transferred to the blade portion 93 after exceeding the gap portion 94 does not decrease extremely. The developer 293a that has fallen onto the blades 92 without being restricted by the ribs 95 is mixed with the developer 292 that has been conveyed by the blades 92.

Subsequently, as shown in FIG. 8B, a part of the mixture of the developer 292 and the developer 293a is separated by scooping up the rib 95 and sent to the blade portion 93. As described above, the developer is exchanged between the blades 92 and 93 regardless of the amount of the developer, so that the developer can be efficiently agitated. That is, it is possible to achieve both the agitation property and the transportability of the developer, and to obtain a stable agitation property even if the amount of the developer fluctuates.

The first transfer screw 64 is a multi-thread screw similar to the second transfer screw 65, but none of the blades is provided with a gap. Further, the first transfer screw 64 is preferably a screw having the same three blades as the second transfer screw 65. That is, the first transfer screw 64 is preferably a screw having the same outer diameter and pitch as the second transfer screw 65 and having the same number of threads. In this case, a gap portion is provided like the second transfer screw 65. It may be possible, and it is not necessary to provide a gap portion.

As described above, in the developing apparatus 6 of the present embodiment, the rib 95 is provided at the downstream end portion 93a of the blade portion 93 facing the upstream side in the rotation direction R1 of the gap portion 94. Therefore, even when the amount of the developing agent is small, a part of the developing agent that is about to return through the gap portion 94 can be conveyed in the conveying direction D3, so that the blade portion 92 and the blade portion 93 can be conveyed regardless of the amount of the developing agent. The replacement of the developing agent can be promoted. This makes it possible to achieve both agitation and transportability of the developer, and in particular, to obtain stable agitation even if the amount of the developer fluctuates.

Further, according to the image forming apparatus 1 of the present embodiment, since the rib 95 is provided in parallel with the rotation shaft 90 of the second transfer screw 65, it is possible to achieve both the agitation property and the transfer property of the developer in a well-balanced manner. it can.

In the image forming apparatus 1 of the present embodiment described above, in the second transport screw 65, the two blade portions 91 and 92 have a shape continuous with respect to the longitudinal direction X of the rotation shaft 90, and the gap portion is formed. I explained the case of not having it, but it is not limited to this. For example, only one of the three blades 91, 92, and 93 does not have a gap, and the two blades have a gap, or the three blades have a gap. All of 91, 92, and 93 may have voids.

Further, in the image forming apparatus 1 of the present embodiment, the case where the first transport screw 64 has the same three-row screw as the second transport screw 65 and none of the blades has a gap portion has been described. , Not limited to this. For example, the first transport screw 64 may also have a shape in which at least one blade has a gap portion, similarly to the second transport screw 65.

Next, the effects of the second transfer screw 65 of the developing apparatus 6 according to the above-described embodiment were compared and verified with those of the second transfer screw 165 according to the comparative examples of FIGS. 11 to 13.

First, the weight ratios of the developer 292 and the developer 293 for each amount of the developer in the developing container 60 were compared between Examples and Comparative Examples. Each weight ratio was measured when the developer was sufficiently circulated and the developer distribution became a steady state, and the first transfer screw 64 and the second transfer screws 65 and 165 were driven at 610 rpm for 10 seconds. .. The result is shown in FIG.

As shown in FIG. 9, in the comparative example, the developer amount ratio decreased as the developer amount decreased, whereas in the example, the reduction in the developer amount ratio could be suppressed. In particular, in this example, it was confirmed that the developer amount ratio g was 0.8 or more when the developer was used in the above-described embodiment of 120 g or more.

Next, when the stirring property and the transportability were lowered, density unevenness was likely to occur in the solid image on the entire surface due to poor charging of the toner in the developing agent, which was verified. Here, using the second transfer screw 65 of the example and the second transfer screw 165 of the comparative example, an image was actually output and the intensity of occurrence of density unevenness was verified. The maximum in-plane density difference when 10 solid images were output was measured for each amount of the developer in the developing container 60. As the image density, the reflection density measured by a spectroscopic densitometer (manufactured by X-Rite) was used. The result is shown in FIG.

As shown in FIG. 10, in both Examples and Comparative Examples, the maximum density difference in the image plane tended to increase as the amount of the developer in the developing container 60 decreased. However, in the configuration of this example, even if the amount of the developer fluctuates, the concentration difference is less likely to occur than in the comparative example. Therefore, according to this example, it was confirmed that both agitation and transportability were achieved and that image unevenness was suppressed.

6 ... developing device, 9 ... accommodating container (replenishment means), 60 ... developing container, 62 ... developing room (first room), 63 ... stirring room (second room), 64 ... first transport screw (first transport member) ), 65 ... 2nd transport screw (second transport member), 66 ... developer replenishment port (replenishment port), 68 ... inductance sensor (detection means), 70 ... developing sleeve (developer carrier), 90 ... rotating shaft , 91 ... blade part, 92 ... blade part (second blade part), 93 ... blade part (first blade part), 93a ... downstream end part, 94 ... gap part, 95 ... rib, 292,293 ... developer , Ar2 ... installation area, D1 ... first direction, D2 ... second direction, R1 ... rotation direction, Sa1 ... first area, Sa2 ... second area, VL1 ... first virtual line, VL2 ... second virtual line, X … Longitudinal direction (rotation axis direction).

Claims (12)

A developer carrier that carries and transports the developer, and
A developing container having a first chamber for supplying the developer to the developer carrier and a second chamber for forming the first chamber and a circulation path for the developer.
A first transport member arranged in the first chamber and transporting the developer in the first direction by rotation, and a first transport member.
A rotation shaft arranged in the second chamber and rotatably provided with respect to the development container, and a spirally formed around the rotation shaft, the developer is rotated in the rotation direction in the direction of the rotation axis. A second transport member having a plurality of blades for transporting in a second direction opposite to the first direction, and a second transport member having a plurality of blades.
A replenishment port for replenishing the developing agent from a replenishing means capable of replenishing the developing container,
A developing apparatus provided in the second chamber and provided with a detecting means for detecting information on the toner concentration of the developing agent in the second chamber.
Of the plurality of blades, at least one first blade is in at least a part of the installation area between the downstream end of the supply port and the upstream end of the detection means in the second direction. From the gap portion where the first blade portion is discontinuous and the downstream end portion in the rotation direction facing the gap portion to the upstream side in the second direction. The shape is continuous and has ribs provided with a gap between the first blade portion and the second blade portion which are located adjacent to each other on the upstream side in the second direction.
A developing device characterized by this. The rib sets a first virtual line along the rotation axis of the second transport member from the downstream end of the first blade, and from the downstream end of the first blade to the gap. When the second virtual line is set, it is provided within the range from the first virtual line to the second virtual line.
The developing apparatus according to claim 1. The rib is provided on the first virtual line.
The developing apparatus according to claim 2. The rib is provided so that the length of the gap in the rotation axis direction is 0.7 to 1.3 times the length of the rib in the rotation axis direction.
The developing apparatus according to any one of claims 1 to 3. The ribs are provided so that the length of the gap in the direction of the rotation axis is the same as the length of the rib in the direction of the rotation axis.
The developing apparatus according to claim 4. When the rib and the gap are viewed from the circumferential direction at the arrangement position of the rib and the gap, the area of the rib is set as the first area, and the area of the gap is defined as the rotation of the rib and the second blade portion. When the second area is based on the distance in the axial direction and the height of the second blade portion from the rotation axis,
The ribs are provided so that the second area is 0.7 to 1.3 times the area of the first area.
The developing apparatus according to any one of claims 1 to 5, wherein the developing apparatus is characterized by this. The rib is provided so that the second area is the same as the first area.
The developing apparatus according to claim 6. The rib is provided so as to have an outer diameter equal to or smaller than the outer diameter of the first blade portion.
The developing apparatus according to any one of claims 1 to 7. The rib is provided so as to have the same outer diameter as the outer diameter of the first blade portion.
The developing apparatus according to claim 8. The first blade portion is formed so that the volume of one row of the first blade portion is 75% or less of the volume of one row of the other blade portion having no gap portion.
The developing apparatus according to any one of claims 1 to 9, wherein the developing apparatus is characterized by this. The first blade portion is formed so that a region having a plurality of the gap portions in one pitch exists at at least one location in the installation region.
The developing apparatus according to any one of claims 1 to 10. The plurality of articles is 3 articles,
One of the three blades is the first blade.
The remaining two of the three blades are the second blade and the other blades having no gap.
The developing apparatus according to any one of claims 1 to 11.

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