JP2013015723A - Developing device, image forming apparatus, and method of stirring developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent scattering of toner in a developing device even with a simple configuration and to quickly stir supplied toner and developer in the device.SOLUTION: A developing device comprises: a developing part 20 including rotating members 21, 22 therein for stirring a developer containing powders; an air blowing part 11 for blowing air; a first duct 12 which connects the air blowing part 11 and the developing part 20; and a second duct 13 which connects the developing part 20 and the air blowing part 11. A first connection part 121 where the developing part 20 and the first duct 12 are connected is provided more towards the gravity direction than the position of a prescribed interface K between the developer and air in the developing part 20, and a second connection part 131 where the developing part 20 and the second duct 13 are connected is provided more towards the opposite side of the gravity direction than the position of the prescribed interface K.

Description

  The present invention relates to a developing device, an image forming apparatus, and a developer stirring method.

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a developer is supplied from a developing device to an electrostatic latent image formed on an image carrier such as a photoconductor, and an electrostatic image formed on the image carrier. Develop the latent image.
Inside the developing device, a rotating member having a spiral blade (screw) and a developing roller are provided. The rotating member agitates the developer in the developing device and conveys the developer to the developing roller by the rotation. The developing roller carries the developer conveyed from the rotating member and supplies it to the image carrier.
Further, as a result of the development as described above, when the amount of toner in the developer in the developing device decreases, the toner is replenished from a toner replenishing portion attached to the developing device.

In such a developing apparatus, there is a demand for a technique for quickly stirring the supplied toner and the developer in the apparatus.
In order to achieve good stirring, it is desirable to stir the developer using not only the rotating member but also an air fluidized bed.
For example, Patent Document 1 proposes a technique for ejecting air from the upstream side in the developer transport direction in the developing device. Patent Document 2 proposes a technique for introducing air from the bottom of the developing device.

JP 2008-026572 A JP 2010-096389 A

  However, when stirring is performed using air as in Patent Documents 1 and 2, there is a problem that toner is scattered in the developing device due to the air introduced into the developing device. In order to prevent scattering of the toner, for example, means such as adding a filter can be considered. However, in such a case, there is a problem that maintenance operation such as replacement of the filter occurs.

  The present invention has been made in view of the above problems, and an object thereof is to prevent scattering of the toner in the developing device while having a simple configuration, and to quickly agitate the supplied toner and the developer in the device. An image forming apparatus including the developing device, and a developer stirring method using the developing device.

To solve the above problem,
The invention according to claim 1 is the developing device,
A developing section having a rotating member for stirring the developer inside;
An air blowing section for sending out air;
A first duct connecting the blower and the developing unit;
A second duct connecting the developing unit and the blowing unit;
With
A first connecting portion to which the developing portion and the first duct are coupled is provided closer to a gravitational direction side than a predetermined interface position between the developer and air in the developing portion;
The second connecting portion where the developing portion and the second duct are connected is provided on the opposite side of the gravitational direction from the position of the predetermined interface.

The invention according to claim 2 is the developing device according to claim 1,
A cross-sectional area of the first connection portion is smaller than a cross-sectional area of the second connection portion.

According to a third aspect of the present invention, in the developing device according to the first or second aspect,
A part of the first duct is provided with a curved portion curved in a direction opposite to the direction of gravity.

The invention according to claim 4 is the developing device according to any one of claims 1 to 3,
The rotating direction of the rotating member and the direction in which the air inserted from the first connection portion floats face each other.

According to a fifth aspect of the present invention, in the developing device according to the first aspect,
The first connection part includes a porous body having a large number of pores.

A sixth aspect of the present invention provides the developing device according to any one of the first to fifth aspects,
The second connection part may include a rectifying member.

The invention described in claim 7 is the developing device according to claim 6,
The rectifying member has a honeycomb structure.

The invention according to claim 8 is the developing device according to any one of claims 1 to 7,
Two soft members are provided above the predetermined interface in the developing portion so as to sandwich the second connecting portion along the axial direction of the rotating member.

The invention according to claim 9 is the developing device according to any one of claims 1 to 7,
In the developing unit, two rotating members are provided,
A partition member is provided between the two rotating members above the predetermined interface in the developing unit along the axial direction of the two rotating members.

A tenth aspect of the present invention is the developing apparatus according to any one of the first to ninth aspects,
A crushing unit connected to the first duct and crushing the powder lump;
The grinding part is
A pulverization chamber having a circular shape in cross-sectional view for pulverizing a powder lump by a swirling flow of air;
Upstream of the crushing chamber, at least one inflow portion connected to the blower side of the first duct;
Downstream of the pulverization chamber, an outflow portion connected to the developing portion side of the first duct;
With
The inflow portion flows air in a direction along a tangential direction of a cross-sectional circle of the grinding chamber,
The outflow part is characterized in that air flows out in a direction along a rotation axis direction of a swirling flow in the crushing chamber.

The invention according to claim 11 is the developing device according to claim 10,
The outflow portion is formed in a cylindrical shape, and includes a wedge-shaped protrusion.
The protrusion is inserted into the first duct on the developing unit side.

The invention according to claim 12 is the developing device according to claim 10 or 11,
The rotational axis direction of the swirling flow in the grinding chamber is equal to the direction of gravity.

A thirteenth aspect of the present invention is the developing device according to any one of the tenth to twelfth aspects,
A container for storing powder is connected to the vicinity of the inflow portion of the grinding chamber,
The container is provided with a powder release valve,
The powder is discharged into the crushing chamber by opening the powder discharge valve.

According to a fourteenth aspect of the present invention, in the developing device according to the thirteenth aspect,
The distance (R) between the rotational axis of the swirling flow in the grinding chamber and the central axis of the powder discharge valve and the maximum diameter (D) of the cross-sectional circle of the grinding chamber are 0 <R <D / 2. It is characterized by satisfying the relationship.

According to a fifteenth aspect of the present invention, in the image forming apparatus,
A developing device according to claim 1 is provided.

The invention described in claim 16
In the stirring method of the developer by the developing device according to any one of claims 1 to 14,
The air in the developing unit is circulated by rotating the rotating member, supplying air from the blowing unit to the developing unit, and discharging the air in the developing unit to the blowing unit. To do.

According to the present invention, the first connection portion is provided on the gravity direction side from the predetermined interface between the powder and the air in the developing unit, and the second connection portion is on the opposite side of the gravity direction from the predetermined interface. Provided.
For this reason, an air circulation path is formed in the developing section, and the flow mass of air supply and discharge is preserved, so that the developer can be agitated without scattering the developer.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. It is the schematic which shows the structure of a developing device. It is a figure for demonstrating the structure of a developing device. FIG. 10 is a diagram for explaining a configuration of a developing device according to a first modification. FIG. 10 is a diagram for explaining a configuration of a developing device according to a second modification. FIG. 10 is a diagram for describing a configuration of a developing device according to a third modification. FIG. 10 is a diagram for explaining a configuration of a developing device according to modification example 4; FIG. 10 is a diagram for explaining a configuration of a developing device according to a modified example 5; FIG. 10 is a diagram for explaining a configuration of a developing device according to a modified example 6; FIG. 10 is a diagram for explaining a configuration of a developing device according to a modified example 7; It is the schematic which shows the whole structure of the image forming apparatus of 2nd Embodiment. It is the schematic which shows the structure of a grinding | pulverization part. It is a figure for demonstrating the detailed structure of a grinding | pulverization part. It is the schematic which shows the whole structure of the image forming apparatus of 3rd Embodiment. It is the schematic which shows the structure of a grinding | pulverization part. It is a figure for demonstrating the detailed structure of a grinding | pulverization part.

  Embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

[First Embodiment]
FIG. 1 is a schematic diagram showing the overall configuration of the image forming apparatus according to the first embodiment of the present invention.
As shown in FIG. 1, the image forming apparatus 1 includes yellow (Y), magenta (M), cyan (C), and black formed on four image carriers (photosensitive drums 2Y, 2M, 2C, and 2K). This is a tandem color image forming apparatus that transfers each toner image of (B) onto an intermediate transfer member (intermediate transfer belt 4) and superimposes them, and then secondary-transfers them onto a sheet.

Specifically, four photosensitive drums 2 (2Y, 2M, 2C, 2K) are vertically arranged in the center of the inside of the image forming apparatus 1. Each photosensitive drum 2 is driven to rotate counterclockwise.
Each photosensitive drum 2 is provided with a developing device 3 (3Y, 3M, 3C, 3K) for each color so as to face the drum. In FIG. 1, only the developing device 3Y is displayed.
A cleaning device, a charging device, and an exposure device (not shown) are arranged around each photosensitive drum 2.

Each photosensitive drum 2 is in contact with the intermediate transfer belt 4.
The intermediate transfer belt 4 is driven to rotate in the clockwise direction, and has a primary transfer device (not shown) at a position facing each developing device 3 inside thereof.

  The toner images of the respective colors are formed on the photosensitive drums 2Y, 2M, 2C, and 2K by the above charging, exposing, and developing devices, and transferred onto the intermediate transfer belt 4 by the primary transfer device. The color toner image formed on the intermediate transfer belt 4 is secondarily transferred to a sheet supplied from a sheet feeding device 5 below the image forming apparatus 1, fixed by the fixing device 6, and discharged.

FIG. 2 shows a schematic configuration diagram of the developing device 3.
The developing device 3 includes a developing unit 20 and an air circulation mechanism 10 that circulates air in the developing unit 20.

  The developing unit 20 includes, for example, rotating members 21 and 22, a developing roller 23, and the like.

The rotating members 21 and 22 have spirally connected blades (screws), and by the rotation, the developer composed of toner and carrier housed in the developing unit 20 is agitated and the developer is developed. Transport to the roller 23 side.
The developing roller 23 carries the developer conveyed by the rotating members 21 and 22 and supplies it to the photosensitive drum 2. The photosensitive drum 2 and the developing roller 23 are provided at positions facing each other with a slight gap, and the toner contained in the developer carried on the developing roller 23 is between the photosensitive drum 2 and the developing roller 23. The formed electric field flies from the developing roller 23 to the photosensitive drum 2 and is carried on the photosensitive drum 2.
Further, the air inside the developing unit 20 is circulated by the air circulation mechanism 10, and the developer is stirred at this time.

  The air circulation mechanism 10 includes, for example, a blowing unit 11, a first duct 12 that supplies air from the blowing unit 11 to the developing unit 20, a second duct 13 that discharges air from the developing unit 20 to the blowing unit 11, and Etc. are provided.

  The blower unit 11 pushes out air to the developing unit 20 and sucks air from the developing unit 20. As the air blower 11, for example, a diaphragm pump or a Mono pump is preferably used in the case of a small flow rate and a high ventilation resistance, and an axial flow type or sirocco type fan is preferably used in the case of a large flow rate and a low resistance.

The first duct 12 has one end connected to the developing unit 20 and the other end connected to the blowing unit 11, and forms a conveyance path for conveying the air pushed out from the blowing unit 11 to the developing unit 20.
Similarly, the second duct 13 has one end connected to the developing unit 20 and the other end connected to the blowing unit 11, and forms a conveyance path for conveying the air discharged from the developing unit 20 to the blowing unit 11. .
In addition, the 1st duct 12 and the 2nd duct 13 can be formed using flexible tubes, such as a silicon | silicone, for example. Thereby, it is possible to form a conveyance path with a large curvature.

Here, as shown in FIGS. 3A and 3B, the first connecting portion 121, which is a connecting portion between the developing portion 20 and the first duct 12, has a predetermined amount of developer and air in the developing portion 20. It is provided on the gravity direction side (lower side of the developing unit 20) from the position of the interface K.
On the other hand, the second connecting portion 131 that is a connecting portion between the developing unit 20 and the second duct 13 is on the side opposite to the gravitational direction from the position of the interface K, that is, on the side opposite to the first connecting portion 121 with respect to the interface K It is provided on the upper side of the developing unit 20.
Thus, an air circulation path is formed in the developing unit 20 from the lower side (first connecting part 121) to the upper side (second connecting part 131) of the developing unit 20, and the inside of the developing unit 20 The developer is agitated with air.
The first connecting portion 121 can be set on the bottom surface or the side surface of the developing unit 20 as long as it is on the gravity direction side of the interface K, but the first connecting portion 121 and the second connecting portion 131 can be set. Are more preferably provided so as to face each other.
In addition, the second connection portion 131 may be divided into a plurality of parts and arranged near the photosensitive drum 2.

With the above configuration, the developer stirring method as described below is realized in the developing device 3 of the present embodiment.
That is, the rotating members 21 and 22 are rotated, the air from the blower unit 11 is supplied to the developing unit 20 through the first duct 12, and the air in the developing unit 20 is discharged to the blower unit 11 through the second duct 13. As a result, the air in the developing unit 20 is circulated.
Specifically, air is supplied into the developing unit 20 from the lower side of the developing unit 20 (below the interface K), and the air in the developing unit 20 is discharged from the upper side of the developing unit 20 (above the interface K). Is done.
At this time, the flow mass of air supply and discharge is preserved, so that air agitation is possible without scattering the developer.
Moreover, even if the developer is powder or liquid, the density of air is remarkably low, so that the effect of stirring can be obtained.
Further, when the developer is a liquid, the vaporized solvent and its odor do not leak.
In particular, when the developer is a liquid, a plurality of first connection parts 121 set in parallel so that the diameter of the bubbles is in millimeters or micro units are provided in parallel, and air is supplied from the plurality of first connection parts 121. By doing so, the mixing scale can be adjusted.

As described above, according to the present embodiment, the developing unit 20 provided with the rotating members 21 and 22 for stirring the developer, the air blowing unit 11 that sends out air, and the air blowing unit 11 and the developing unit 20 are connected. A first duct 12 that connects the developing section 20 and the blower section 11, and the first connecting section 121 that connects the developing section 20 and the first duct 12 is the developing section 20. The second connecting portion 131 provided on the gravity direction side from the position of the predetermined interface K between the developer and air inside and connecting the developing section 20 and the second duct 13 is from the position of the predetermined interface K. Is also provided on the opposite side of the direction of gravity.
For this reason, an air circulation path is formed in the developing unit 20 from the lower part to the upper part of the developing part 20, and the flow mass of air supply and discharge is preserved, so that the developer is not scattered. Can be achieved.
Further, since the developer is not scattered, there is no need to provide a member corresponding to the scattering such as a filter.

In the above-described embodiment, the air from the blowing unit 11 is supplied to the developing unit 20 by the first duct 12, and the air of the developing unit 20 is discharged to the blowing unit 11 by the second duct 13. The configuration in which air is inserted and circulated from the bottom has been described as an example. However, the operation direction of the air blowing unit 11 is reversed, the air from the air blowing unit 11 is supplied to the developing unit 20 by the second duct 13, and the first duct 12, the air of the developing unit 20 can be discharged to the blower unit 11.
In this case, the developer is dropped from above and stirring is performed.

  Further, it is possible to use a single air blowing unit 11 for the plurality of developing units 20.

Next, modified examples of the first duct 12 and the second duct 12 will be described with reference to FIGS.
4 to 9, only the rotating member 21 of the developing unit 20 is illustrated.

[Modification 1]
FIG. 4A is a schematic diagram illustrating the configuration of the air circulation mechanism 10 of Modification 1, and FIG. 4B is a diagram of FIG. 4A viewed from the side of the rotating member 21.
In the first modification, as shown in FIG. 4B, the first duct 12 and the second duct 13 have a cross-sectional area (S1) of the first connecting portion 121 that is a cross-sectional area of the second connecting portion 131 (S1). S2) is configured to be smaller (S2> S1).
With this configuration, when air is supplied from the bottom surface of the developing unit 20, the speed of air from the developing unit 20 toward the blowing unit 11 is relatively higher than the speed of air from the blowing unit 11 toward the developing unit 20. Therefore, the developer can be prevented from being transported to the blower unit 11. Further, it is possible to prevent the backflow from the developing unit 20 to the blowing unit 11 when the blowing is stopped.
Here, the second connecting portion 131 has not only a larger cross-sectional area than the first connecting portion 121, but also the shape of the connecting portion between the developing unit 20 and the second duct 13 so that the cross-sectional area does not change abruptly. The shape is R processed. By doing in this way, ventilation resistance can be reduced. In addition, since a local fast flow is prevented, as a result, the developer conveying force is entirely pushed down.

[Modification 2]
5A to 5C are schematic views illustrating the configuration of the air circulation mechanism 10 according to the second modification.
In Modification 2, as shown in FIGS. 5A to 5C, a part of the first duct 12 is configured to have a curved portion 122 that is curved in a direction opposite to the direction of gravity.
With this configuration, an interface K1 is generated in the path of the first duct 12, and the backflow of the developer can be prevented when the blower unit 11 is stopped.
Note that if the cross-sectional area from the developing unit 20 to the curved portion 122 is relatively small, the amount of developer transported is small, and therefore it is possible to suppress the starting power source of the blower unit 11. In particular, when the developing unit 20 is installed at a position lower than the blower unit 11, it is preferable to configure in this way.

[Modification 3]
6A to 6C are schematic views illustrating the configuration of the air circulation mechanism 10 according to the third modification. 6A is an example in which the first connection portion 121 is provided on the bottom surface of the developing unit 20, and FIG. 6B is a view of FIG. 6A viewed from the side of the rotating member 21, FIG. 6C shows an example in which the first connecting portion 121 is provided on the side surface of the developing portion 20.
In the third modification, the first connecting portion 121 is provided so that the rotation direction of the rotating member 21 and the direction in which the air inserted from the first connecting portion 121 floats up. If such setting is possible, the first connecting portion 121 can be provided on either the bottom surface or the side surface of the developing portion 20 as shown in FIGS. 6A and 6C.
In addition, as shown to Fig.6 (a), it is preferable to connect the 1st connection part 121 in the area | region where the X-axis is positive when the rotation axis of the rotation member 21 is made into the origin. At this time, if the first connecting portion 121 is too close to the interface K, the effect of stirring is small. Therefore, if the rotation axis is the origin, the range of θ = 280 to 300 deg (the range indicated by T in the left diagram of FIG. 6A). ) Is more preferable.
By configuring in this way, the jet velocity to the developer increases, so that stirring can be promoted.

[Modification 4]
FIG. 7A is a schematic view showing the configuration of the air circulation mechanism 10 of Modification 4, and FIG. 7B is a view of FIG. 7A viewed from the side of the rotating member 21. FIG. 7 (c) is an enlarged view of region A in FIG. 7 (b).
In the modification 4, as shown to Fig.7 (a)-(c), the 1st connection part 121 is provided with the porous body 123 which has many holes.
Examples of the porous body 123 include a porous body made of a single material having pores of various sizes inside and a plurality of particles such as a large number of microspheres and / or polygons. However, other than this, a net-like member made by overlapping wire rods into a net-like shape, a fiber material having pores, a flat plate in which a large number of holes are formed, or the like can also be used.
By comprising in this way, the cross-sectional area of the 1st connection part 121 will be expanded, a ventilation speed | rate can be suppressed and a wide fluidized bed can be formed.
In addition, the same effect can be acquired also when inserting air from the rotating shaft direction of the rotating members 21 and 22. FIG. Further, when the toner or carrier is mixed with air and supplied, it is preferable that the cross-sectional area of the pores is 10 times or more larger than the particles of the toner or carrier.

[Modification 5]
FIG. 8A is a schematic diagram illustrating the configuration of the developing device 20 and the air circulation mechanism 10 of Modification 5, and FIG. 8B illustrates another mode of the rectifying member 132 of FIG. 8A. It is a figure.
In Modification 5, as shown in FIG. 8A, the second connecting portion 131 is provided with a rectifying member 132.
The rectifying member 132 is configured by arranging a plurality of plate bodies 132a... In parallel at a predetermined interval in the radial direction.
At this time, it is preferable that the main surface of the plate body 132a is arranged along the direction of gravity so that the powder and the powder lump attached to the plate body 132a are dropped.
By comprising in this way, since the local quick flow in the 2nd connection part 131 can be suppressed, it can reduce that a particle is conveyed.

Further, as shown in FIG. 8B, the rectifying member 132 may have a honeycomb structure.
By comprising in this way, the intensity | strength can be given to the 2nd connection part 131. FIG.
In this case, it is preferable to use a thin plate as much as possible for the rectifying member 132 so as not to cause ventilation resistance. In this case, it is possible to prevent breakage during installation by using a triangular or hexagonal shape rather than a plate body arranged vertically and horizontally.

[Modification 6]
FIG. 9A is a schematic diagram illustrating the configuration of the developing device 20 and the air circulation mechanism 10 according to Modification 6. FIG. 9B is a diagram of FIG. 9A viewed from the side of the rotating member 21. It is.
In the sixth modification, as shown in FIGS. 9A and 9B, the two connection portions 131 are sandwiched between the second connection portions 131 along the axial direction of the rotating member 21 above the interface K in the developing portion 20. A soft member 14 is disposed.
The soft member 14 is preferably made of a linear member bundled in a brush shape. As the fiber length, it is preferable that the tip end of the fiber is in contact with the interface K because the sealing performance is improved.
Further, when the soft member 14 is disposed, the diameter of the portion of the rotating member 21 that contacts the soft member 14 is reduced, or the portion of the rotating members 21 and 22 that contacts the soft member 14 is cut away. Thus, the sealing property can be further improved.
For the soft member 14, for example, a resin material such as rubber or PET can be used.
By comprising in this way, the flow of air can be limited and scattering of a developer can be prevented more effectively.

[Modification 7]
FIG. 10A is a schematic diagram illustrating the configuration of the developing device 20 and the air circulation mechanism 10 according to the modified example 7, and FIG. 10B illustrates the rotation member 21 and the air circulation mechanism 10 illustrated in FIG. It is the figure seen from the upper side.
In the modified example 7, as shown in FIG. 10A, the partition member 15 is disposed between the rotary members 21 and 22 above the interface K in the developing unit 20 along the longitudinal direction of the rotary members 21 and 22. It is arranged.
As the material of the partition member 15, for example, a soft member similar to that of Modification 6 is used, and its upper end portion 15 a is connected to the upper part of the inner surface of the developing unit 20 and can be moved like a pendulum with the upper end portion 15 a as a fulcrum. Is preferred.
With such a configuration, even when the interface K changes, the torque of the rotating members 21 and 22 can be minimized. Moreover, since the partition member 15 does not contact the rotating members 21 and 22, a soft member with low durability can be used as the partition member 15, and the sealing performance can be improved.

Second Embodiment
Next, a second embodiment of the present invention will be described focusing on differences from the first embodiment.
In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

FIG. 11 is a schematic diagram illustrating the overall configuration of the image forming apparatus according to the second embodiment.
In the image forming apparatus 1 </ b> A of the present embodiment, as shown in FIG. 11, an air circulation in which a pulverization unit 30 that pulverizes a powder lump is connected between the blowing unit 11 and the developing unit 20 of the first duct 12. A developing device 7 (7Y) having a mechanism 10A is provided.
The powder lump is formed by the aggregation of the developer due to the influence of humidity and temperature.
The crushing part 30 of this embodiment is to crush the powder lump by colliding with the inner wall of the crushing part 30 by applying a large centrifugal force to the powder mass by the swirling flow of air. In the following, the powder mass is crushed and expressed as “fine particles”.

Here, FIG. 12A shows a top view of the pulverizing unit 30, FIG. 12B shows a perspective view of the pulverizing unit 30 seen from the side, and FIG. 12C shows the pulverizing unit 30. The schematic diagram which shows an internal structure is shown.
As shown in FIGS. 12A to 12C, the pulverizing unit 30 includes a cylindrical body 32 having a cylindrical appearance, and a pulverizing chamber 31 having a circular cross-section provided inside the cylindrical body 32. In addition, an inflow portion 33 that flows the powder lump into the pulverization chamber 31 together with air, an outflow portion 34 that flows out the fine particles from the pulverization chamber 31 together with air, and the like are provided.
In addition, in this embodiment, although the cylindrical body 32 is supposed to comprise a column shape, it can also be made into a prismatic shape or a cone shape besides this.

The inflow portion 33 is provided in a cylindrical shape so as to communicate with the pulverization chamber 31 from the end of the upper side surface of the cylindrical body 32, and is connected to the first duct 12 on the air blowing portion 11 side.
The inflow portion 33 flows air in a direction along a tangential direction of a circle (cross-sectional circle) when the grinding chamber 31 is viewed in cross section.

The crushing chamber 31 is formed in a conical shape and has a circular cross-sectional view.
In the pulverizing chamber 31, the powder lump that flows in along with the air from the inflow portion 33 swirls, and centrifugal force is applied to the powder lump by the swirling flow. With this action, the powder lump collides with the inner wall of the crushing chamber 31 and is crushed into fine particles. In the crushing chamber 31, the swirling flow is kept long even downstream of the path of the crushing chamber 31, and the powder is prevented from being biased only in one direction such as the direction of gravity.
Further, it is preferable that the crushing chamber 31 be configured so that its cross-sectional area is gradually changed, since the connection of the inflow portion 33 to the second duct 12 is smooth and powder can be prevented from sticking.
Further, the rotational axis direction of the swirling flow in the crushing chamber 31 is set to be equal to the direction of gravity. For this reason, when the downstream of the conveyance path is directed downward as in the present embodiment, it is difficult for the powder to flow backward toward the blowing unit 11 when the crushing unit 30 is stopped.
Even when the crushing unit 30 is provided with the downstream of the conveyance path facing upward, a large powder lump goes downstream by installing the swirl flow in the crushing chamber 31 so that the rotational axis direction of the swirling flow is equal to the gravity direction. This can be prevented.
The crushing chamber 31 has a lower resistance to ventilation as its cross section is closer to a circle, and can form a strong swirling flow. Therefore, the crushing chamber 31 preferably has a circular cross-sectional view. It is also preferable to use a columnar shape or the like, but in addition to this, the crushing chamber may be formed in a prismatic shape having a polygonal sectional view.

The outflow portion 34 is provided in a cylindrical shape along the rotational axis direction of the swirling flow in the crushing chamber 31 on the downstream side of the conveyance path in the crushing chamber 31, and is connected to the first duct 12 on the developing unit 20 side. .
At this time, as shown in FIG. 13, the outflow portion 34 may be provided with a wedge-shaped protrusion 34 a.
By doing in this way, it is possible to use the tube which expands / contracts to the outflow part 34, and it can make it difficult to pull out while being easy to connect. The wedge-shaped protrusions described above can also be used for the inflow portion 33.
Further, by making the diameters of the inflow portion 33 and the outflow portion 34 equal, a smooth flow can be formed when the pulverizing portion 30 is installed in series.

As described above, according to the present embodiment, the pulverization unit 30 that is connected to the first duct 12 and pulverizes the powder mass is provided, and the pulverization unit 30 has a cross-section that pulverizes the powder mass by the swirling flow of air. The pulverization chamber 31 having a circular shape, at least one inflow portion 33 connected to the air blowing unit 11 side of the first duct 12 at the upstream side in the pulverization chamber 31, and the first duct 12 at the downstream side in the pulverization chamber 31. And an outflow portion 34 connected to the developing unit 20 side, the inflow portion 33 inflows air in a direction along the tangential direction of the cross-sectional circle of the crushing chamber 31, and the outflow portion 34 swivels in the crushing chamber 31. For this reason, a large centrifugal force is applied to the powder mass by the swirling flow, and the powder can collide with the inner wall of the pulverizing unit to be pulverized.
In addition, since the swirling flow continues even downstream of the path along which the powder mass is conveyed, it is possible to prevent the powder from being biased in only one direction such as the gravitational direction.

In addition, according to the present embodiment, the outflow portion 34 is formed in a cylindrical shape, includes a wedge-shaped protrusion 34 a, and the protrusion 34 a is inserted into the first duct 12 on the developing unit 20 side.
For this reason, the connection of the outflow portion 34 to the first duct 12 is easy, but it is difficult to come out.

Further, according to the present embodiment, the rotational axis direction of the swirling flow in the crushing chamber 31 is equal to the direction of gravity.
For this reason, when the downstream is faced downward, it is difficult for the powder to flow backward toward the blowing part 11 when the crushing part 30 is stopped, and when the downstream is faced upward, a large powder mass goes downstream. Can be prevented.

<Third Embodiment>
Next, a third embodiment of the present invention will be described focusing on differences from the second embodiment.
In addition, about the structure similar to 2nd Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

FIG. 14 is a schematic diagram illustrating the overall configuration of the image forming apparatus according to the third embodiment.
In the image forming apparatus 1B of the present embodiment, as shown in FIG. 14, the developing device 8 (8Y) has a container 40 for storing powder (toner) connected in the vicinity of the inflow portion 33 of the pulverizing portion 30. An air circulation mechanism 10B is provided.
Specifically, as shown in FIG. 15, a container 40 is provided in the upper part of the crushing chamber 31. The container 40 is provided with a powder release valve 41 that operates up and down. By operating the powder release valve 41, the powder release valve 41 is opened and the powder is discharged to the pulverizing unit 30. ing.
For this reason, powder will be thrown into the swirl flow several times faster than the speed in the inflow part 33, and it is possible to grind | pulverize a powder lump finely.

Here, the flow is extremely slow in the vicinity of the inner wall of the crushing chamber 31, but the static pressure is high due to the centrifugal force. Therefore, the installation position of the powder release valve 41 is preferably slightly outside the center of the crushing chamber 31. .
Specifically, as shown in FIG. 16, the distance (R) between the rotational axis P1 of the swirling flow in the crushing chamber 31 and the central axis P2 of the powder discharge valve 41 and the maximum diameter of the cross-sectional circle of the crushing chamber 31 (D) preferably satisfies the relationship 0 <R <D / 2.
By setting in this way, since the tangential direction component of the composite vortex of Rankine corresponds to a large position, the centrifugal force becomes large, and the effect of pulverization can be increased.

In addition, in order to generate many disturbances, when a protruding member is arranged on the inner wall of the crushing chamber 31 or a wire is installed, an unsteady vortex motion occurs due to the vortex generated therefrom, and the effect of stirring can be further enhanced. .
Further, in this embodiment, the powder is discharged from the upper side of the pulverizing unit 30, but a powder release valve 41 may be provided on the side surface of the pulverizing unit 30.
Further, the powder may be discharged with a screw or a rotary rotor.
In order to promote mixing of a plurality of types of powders, two or more powder discharge valves 41 may be provided and discharged simultaneously during the swirling flow.

  Further, it is preferable to arrange the container 40 on the opposite side of the direction of gravity from the developing unit 20 because it can be operated with a small power source.

As described above, according to the present embodiment, the container 40 for storing the powder is connected to the vicinity of the inflow portion 33 of the pulverizing unit 30, and the powder release valve 41 is provided in the container 40. By opening the release valve 41, the powder is released to the pulverizing unit 30.
For this reason, powder will be thrown into the swirl flow several times faster than the speed in the inflow part 33, and it is possible to grind | pulverize a powder lump more finely.

Further, according to the present embodiment, the inter-axis distance (R) between the rotational axis of the swirling flow in the crushing chamber 31 and the central axis of the powder discharge valve 41, and the maximum diameter (D) of the cross-sectional circle of the crushing chamber 31 However, the relationship 0 <R <D / 2 is satisfied.
For this reason, a centrifugal force becomes large and the effect of a grinding | pulverization can be enlarged.

  In the second and third embodiments, when the ventilation resistance of the system is large, the pulverizing units 30 can be arranged in parallel.

  Also in the second and third embodiments, it is needless to say that the first to seventh modifications described above can be applied as the configurations of the first duct 12, the second duct 13, and the developing unit 20.

  The image forming apparatus of the present invention is not limited to the above-described configuration, and may be any known copying machine, printer, monochrome / color in an MFP, or the like.

1, 1A, 1B Image forming device 2 Photosensitive drums 3, 7, 8 Developing device 4 Intermediate transfer belt 5 Paper feeding device 6 Fixing device 10, 10A, 10B Air circulation mechanism 11 Blow unit 12 First duct 121 First connection unit 122 Curved portion K1 Interface 123 Porous body 13 Second duct 131 Second connection portion 132 Rectifying member 132a Plate body 14 Soft member 15 Partition member 15a Upper end portion 20 Developing portion 21, 22 Rotating member 23 Developing roller 30 Grinding portion 31 Grinding chamber 32 Cylindrical body 33 Inflow part 34 Outflow part 34a Protrusion part 40 Container 41 Powder release valve

Claims (16)

A developing section having a rotating member for stirring the developer inside;
An air blowing section for sending out air;
A first duct connecting the blower and the developing unit;
A second duct connecting the developing unit and the blowing unit;
With
A first connecting portion to which the developing portion and the first duct are coupled is provided closer to a gravitational direction side than a predetermined interface position between the developer and air in the developing portion;
2. A developing device according to claim 1, wherein a second connecting portion for connecting the developing portion and the second duct is provided on a side opposite to the gravitational direction from the position of the predetermined interface.   The developing device according to claim 1, wherein a cross-sectional area of the first connection portion is smaller than a cross-sectional area of the second connection portion.   The developing device according to claim 1, wherein a part of the first duct is provided with a curved portion that is curved in a direction opposite to the direction of gravity.   The developing device according to claim 1, wherein a rotation direction of the rotating member and a direction in which the air inserted from the first connection portion rises face each other.   The developing device according to claim 1, wherein the first connection portion includes a porous body having a large number of pores.   The developing device according to claim 1, wherein a rectifying member is provided in the second connection portion.   The developing device according to claim 6, wherein the rectifying member has a honeycomb structure.   The two soft members are provided above the predetermined interface in the developing section so as to sandwich the second connecting section along the axial direction of the rotating member. The developing device according to claim 1. In the developing unit, two rotating members are provided,
The partition member is provided between the two rotating members above the predetermined interface in the developing unit along the axial direction of the two rotating members. The developing device according to one item. A crushing unit connected to the first duct and crushing the powder lump;
The grinding part is
A pulverization chamber having a circular shape in cross-sectional view for pulverizing a powder lump by a swirling flow of air;
Upstream of the crushing chamber, at least one inflow portion connected to the blower side of the first duct;
Downstream of the pulverization chamber, an outflow portion connected to the developing portion side of the first duct;
With
The inflow portion flows air in a direction along a tangential direction of a cross-sectional circle of the grinding chamber,
The developing device according to claim 1, wherein the outflow portion flows out air in a direction along a rotation axis direction of a swirling flow in the pulverization chamber. The outflow portion is formed in a cylindrical shape, and includes a wedge-shaped protrusion.
The developing device according to claim 10, wherein the protrusion is inserted into the first duct on the developing unit side.   The developing device according to claim 10 or 11, wherein a rotation axis direction of the swirling flow in the pulverization chamber is equal to a gravity direction. A container for storing powder is connected to the vicinity of the inflow portion of the grinding chamber,
The container is provided with a powder release valve,
The developing device according to claim 10, wherein the powder is discharged into the pulverization chamber by opening the powder discharge valve.   The distance (R) between the rotational axis of the swirling flow in the grinding chamber and the central axis of the powder discharge valve and the maximum diameter (D) of the cross-sectional circle of the grinding chamber are 0 <R <D / 2. The developing device according to claim 13, wherein the relationship is satisfied.   An image forming apparatus comprising the developing device according to claim 1. In the stirring method of the developer by the developing device according to any one of claims 1 to 14,
The air in the developing unit is circulated by rotating the rotating member, supplying air from the blowing unit to the developing unit, and discharging the air in the developing unit to the blowing unit. The developer stirring method.

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