JP2002006599A - Developing device and image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device and an image-forming device which realizes improvement in image quality by reducing offsetting of developer in the device. SOLUTION: By providing a barrier 13 immediately in front of an aperture part 12 provided on the downstream end of a developing chamber 3, so that it cuts off the base part of the chamber 3, the developer is accumulated in the vicinity of the downstream end and the amount of the developer carried from the chamber 3 to a stirring chamber 4 through the aperture part 12 is regulated to be equal to or under the fixed amount, then the deviation of the distribution of the amount of the developer in the chamber 3 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing a latent image formed on an image carrier by attaching a developer thereto. The present invention relates to a developing device applied to an image forming apparatus such as a copying machine and a laser beam printer using a recording method.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine using an electrophotographic system, a developer is attached to an electrostatic latent image formed on an image carrier such as a photosensitive drum to form a visible image. In the developing device according to the related art used for such development,
A device using a two-component developer composed of a toner and a carrier is known, and an example thereof is shown in FIG. FIG. 10 is a schematic sectional view of a developing device according to a conventional technique.

As shown in FIG. 10, in a developing device 101 using a two-component developer, a first transport screw 105 and a second transport screw 106 for transporting the two-component developer while stirring the same are horizontally moved by two. There are many things that have this arrangement. The first transport screw 105 supplies the developer to a developer carrier (hereinafter, referred to as a developing sleeve) 108,
It is used to collect the developer after passing through the development area.

[0004] A second conveying screw 106 is used for mixing and stirring the developer recovered from the developing sleeve 108 and the newly supplied developer.

On the other hand, in recent years, in an image forming apparatus using an electrophotographic method, such as a copying machine or a printer, there has been a strong demand for downsizing of the apparatus body in order to save space. In an image forming apparatus,
Since a plurality of developing devices are used, there is a strong demand for miniaturization.

Accordingly, for example, Japanese Patent Application Laid-Open No. Hei 5-333691 discloses
The technology disclosed in the gazette is known. Such a developing device according to the prior art will be described with reference to FIGS. 11 and 12 are schematic cross-sectional views of a developing device according to the related art. FIG. 11 shows a cross section perpendicular to the axial direction of a developing sleeve and a conveying screw, and FIG. 12 shows an axial cross section.

The developing device 101 shown in FIG. 11 has two conveying screws 105 and 10 for stirring and conveying the developer.
6 is arranged vertically. More specifically, the developing device 101 includes a developing container 102 containing a developer, and a photosensitive drum 110 of the developing container 102.
The developing sleeve 108 is provided at the opening facing the developing sleeve 108.

On the side opposite to the opening in the developing container 102, a developing chamber 103 and an agitating chamber 104 partitioned by a partition wall 107 are formed vertically, and the developing chamber 103 and the agitating chamber 104 are provided inside the developing chamber 103 and the agitating chamber 104, respectively. A first transport screw 105 and a second transport screw 106 are provided as a means for stirring and transporting the developer.

The first transport screw 105 is connected to the developing chamber 10
3 and a second conveying screw 1
06, the new toner supplied into the stirring chamber 104 from the toner supply port on the upstream side of the second conveying screw 105 and the developer already in the stirring chamber 104 are conveyed while stirring, and Uniform toner concentration.

As described above, the vertical stirring type developing device 101 shown in FIG.
Are arranged in the vertical direction, so that the space occupied in the horizontal direction can be reduced.For example, a color image forming apparatus such as a tandem type in which a plurality of developing apparatuses are mounted in parallel in the horizontal direction can be downsized. It becomes possible.

Further, the vertical stirring type developing device has the following advantages.

That is, as shown in FIG. 11, after being carried on the developing sleeve 108 and conveyed to the developing area, and subjected to the developing, the remaining developer not subjected to the developing in the developing area is transferred to the developing sleeve 108. With the rotation of the developing chamber 10
Only the developer sufficiently stirred in the stirring chamber 104 always exists in the developing chamber 103 because the developer is not collected in the stirring chamber 104 but collected in the stirring chamber 104.

For this reason, the developing sleeve 108 is always supplied with the developer having a uniform density, and image unevenness in the thrust direction (image unevenness caused by insufficient stirring) and density difference (due to insufficient stirring). It is possible to obtain a uniform image without any density difference.

[0014]

However, in the case of the above-described prior art, the following problems have occurred.

As described above, the vertical stirring type developing device has an advantage of being suitable for miniaturization and an advantage of being able to return the developer not subjected to development to the stirring chamber, but has the following problems. Exists.

As shown in FIG. 12, the first conveying screw 105 is disposed substantially parallel to the bottom of the developing chamber 103 along the axial direction of the developing sleeve 108. The agent is conveyed in one direction along the axial direction.

The second transport screw 106 is disposed at the bottom of the stirring chamber 104 substantially parallel to the first transport screw 105, and transfers the developer in the stirring chamber 104 with the transport direction of the first transport screw 105. Transport in the opposite direction.

As described above, the developer is conveyed by the rotation of the first conveying screw 5 and the second conveying screw 106, and the developer is supplied to the openings 111, 1 at both ends of the partition 107.
12 circulates between the developing chamber 103 and the stirring chamber 104.

By the way, in such a developing device 101, since the developing chamber 103 and the stirring chamber 104 are arranged vertically, as shown in FIGS.
The developer from the stirring chamber 104 to the stirring chamber 104 moves from top to bottom, and the developer from the stirring chamber 104 to the developing chamber 103 moves from bottom to top.

In particular, the developer is delivered from the stirring chamber 104 to the developing chamber 103 so as to be pushed upward from below by the pressure of the developer accumulated at the end. FIG. 13 shows the agent circulation path at this time. However, not all of the developer delivered from the stirring chamber 104 to the developing chamber 103 reaches the downstream end of the first transport screw 105 in the developing chamber. Are supplied to the developing sleeve 108 and are collected in the stirring chamber 104 after passing through the developing area.

The path of this component is shown by an arrow a in FIG.
The delivery of the developer to the developing sleeve 108 is performed over almost the entire width of the developing sleeve 108. Therefore, the amount of the developer transported by the first transport screw 105 in the developing chamber 103 tends to gradually decrease from the upstream end to the downstream end. On the other hand, the amount of developer transported by the second transport screw 106 in the stirring chamber 104 tends to gradually increase from the upstream end to the downstream end. That is, the distribution of the developer in the developing device 101 has a bias.

In particular, if the amount of the developer in the developing chamber 103 is deviated, the supply to the developing sleeve 108 becomes uneven, and the density of the image formed due to the unevenness is reduced in the axial direction of the developing sleeve 108. Different. In other words, the supply amount of the developer to the developing sleeve 108 is stable and the image density is constant on the upstream side of the transport path in the developing chamber where the amount of the developer is large. Since the supply amount of the developer to the developing sleeve 108 is small, density unevenness occurs in the image, and an image defect occurs.

As a countermeasure against the above problem, Japanese Patent Application Laid-Open No. 5-33
As in the technique disclosed in Japanese Patent No. 3691, the developer carrying capacity of the first and second carrying screws is made sufficiently larger than the supply amount to the developing sleeve, and the bias effect is relatively reduced. It is also possible. However, when the rotation speed of the conveyance screw is increased to increase the developer conveyance amount, there is a problem that the developer cannot be increased too much because of an increase in stress on the developer and an increase in rotation torque.

Also, when the transport speed is increased by improving the pitch or shape of the transport screw, the upper limit of the transport speed is limited, so that it is not effective when the degree of deviation is severe.

As another countermeasure against the above problem, as disclosed in Japanese Patent Application Laid-Open No. 6-51634, a third conveying screw is provided between a developing sleeve and a second conveying screw provided in a stirring chamber. It is also conceivable to reduce the deviation by providing However, in this case, there is a problem that the configuration of the developing device becomes complicated, which may cause an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a developing apparatus which can improve the image quality by reducing the bias of the developer in the apparatus. And an image forming apparatus.

[0027]

In order to achieve the above object, according to the present invention, there is provided a developer carrier for applying a developer to a developing area to perform development, and a developer carrier provided on the developer carrier. And a stirring chamber disposed below and adjacent to the developing chamber, and a first chamber communicating between the developing chamber and the stirring chamber near both ends in the longitudinal direction of the developing chamber. A communication part and a second communication part are provided, respectively, and a conveyance member for conveying the developer while stirring is provided in each chamber,
The developer is transported from the stirring chamber to the developing chamber via the first communication section by the transport members, and the developer is dropped from the development chamber to the stirring chamber via the second communication section, thereby developing the image. In the developing device for supplying the developer to the developer carrying member while circulating the developer between the chamber and the stirring chamber, the developer is supplied from the developing chamber to the stirring chamber through the second communication portion. The present invention is characterized in that a suppression mechanism for suppressing the amount of fall is provided.

Therefore, the amount of developer falling from the developing chamber to the agitating chamber is suppressed by the suppressing mechanism, so that the developer conveyed in the developing chamber is supplied to the developer carrying member even in the developing chamber. Deviation of the amount of developer is reduced.

It is preferable that the suppression mechanism has a barrier protruding upward from a bottom surface of the developing chamber.

Preferably, the barrier is provided near the second communication portion.

[0031] The suppression mechanism may be configured by providing the second communication portion above a bottom surface of the developing chamber.

The transport member provided in the developing chamber may be a transport screw rotatably provided, and the second communication portion may be provided above an axis of a rotary shaft of the transport screw.

[0033] It is preferable that the restraining mechanism is configured to reduce a transfer capability of a transfer member provided in the developing chamber in the vicinity of the second communication portion.

The conveying member is constituted by a screw having blades, and it is preferable to adjust at least one of the pitch, size, shape and presence or absence of ribs between the blades.

It is preferable that the suppression mechanism has a suction means for applying an upward suction force to the developer near the second communication portion.

The attraction means may be a magnetic field generating means for applying a magnetic attraction force.

The magnetic field generating means is preferably a magnet provided on the ceiling of the developing room.

Preferably, the magnetic field generating means is a coil wound so as to surround the second communication portion.

The developer comprises a toner and a carrier.
It is preferable that a toner supply unit for supplying new toner is provided near the generation of the magnetic field by the magnetic field generation unit, which is a component developer.

It is preferable that the suppression mechanism has a screw provided with a paddle that is rotated by the developer passing through the second communication portion.

In the image forming apparatus of the present invention,
Latent image means for forming a latent image on the image carrier, and the developing device for developing the latent image formed by the latent image means,
It is characterized by having.

[0042]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

In the following description, an image forming apparatus for forming a full-color image will be described as an example of the image forming apparatus. However, the image forming apparatus to which the developing device according to the present embodiment is applied is described below. Needless to say, the present invention is not limited to such a device.

(First Embodiment) A developing device and an image forming apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

First, referring to FIG. 1 and FIG. 2, a schematic configuration of the image forming apparatus and a schematic configuration of the entire developing device will be described. FIG. 1 is a schematic sectional view of a developing device according to an embodiment of the present invention, and schematically shows an image carrier (photosensitive drum) provided inside an image forming apparatus main body and a developing device. . FIG. 2 is a schematic sectional view of a main part of the image forming apparatus according to the embodiment of the present invention.

As shown in FIG. 2, it is known that a full-color image forming apparatus is provided with respective stations for Y, M, C, and Bk, and FIG. It is shown.

Each of the Y, M, C, and Bk stations has substantially the same configuration. In a full-color image, yellow (Y), magenta (M), cyan (C), and black (Bk) images are respectively provided. To form

In the following description, if there is the developing device 1, the developing device 1Y, the developing device 1M, the developing device 1C, and the developing device 1K in each of the Y, M, C, and Bk stations are commonly referred to. Further, in FIG. 2, reference numerals of respective components are added with Y, M, C, and Bk, but description thereof is omitted.

First, the operation of the entire image forming apparatus will be described with reference to FIG.

The photosensitive drum 10 serving as an image carrier is rotatably provided, and the surface of the photosensitive drum 10 is uniformly charged by the primary charger 21 and then, for example, on the uniformly charged surface, for example. An electrostatic latent image is formed by exposing with light modulated according to an information signal by a light emitting element 22 as a latent image means such as a laser. The electrostatic latent image thus formed is visualized as a toner image by the developing device 1.

Next, the visible image is transferred by the transfer charger 23 to the transfer paper 27 conveyed by the transfer paper conveyance sheet 24, and further fixed by the fixing device 25 to obtain a permanent image. The transfer residual toner on the photosensitive drum 10 is removed by the cleaning device 26. Further, the toner consumed in the image formation is supplied from the toner supply tank 20.

Next, the operation of the developing device 1 will be described with reference to FIG.

The developing device 1 according to the present embodiment performs development by applying a developer to a developing area in a developing container 2 containing a two-component developer containing a non-magnetic toner and a magnetic carrier. And a spike member 9 for regulating the spikes of the developer carried on the developing sleeve 8. A substantially central portion in the developing container 2 is vertically divided into a developing chamber 3 and a stirring chamber 4 by a partition wall 7 extending in a direction perpendicular to the sheet of FIG. 4.

A first conveying screw 5 and a second conveying screw 6 are arranged in the developing chamber 3 and the stirring chamber 4 as a developer stirring / conveying member, respectively.

The first transport screw 5 is disposed substantially parallel to the bottom of the developing chamber 3 along the axial direction of the developing sleeve 8, and rotates to transfer the developer in the developing chamber 3 along the axial direction. Convey in one direction.

The second conveying screw 6 is provided in the stirring chamber 4
The developer is disposed substantially parallel to the first transport screw 5 at the bottom thereof, and transports the developer in the stirring chamber 4 in a direction opposite to the transport direction of the first transport screw 5.

As described above, the developer is conveyed by the rotation of the first and second conveying screws 5 and 6, and the developer is provided at both ends of the partition wall 7 with the opening 11 as the first communication part and the second part. The developer is circulated between the developing chamber 3 and the stirring chamber 4 through the opening 12 as a communication part.

Further, an opening is provided at a position corresponding to a developing region of the developing container 2 facing the photosensitive drum 10, and the developing sleeve 8 is rotatable so that a part of the developing sleeve 8 is exposed in the direction of the photosensitive drum 10. It is arranged in. The developing sleeve 8 is made of a non-magnetic material, and a magnet roller serving as a magnetic field means is installed in a non-rotating state inside the developing sleeve 8. The developing roller S1 has a magnet roller developing pole S1 and a magnetic pole S2 which carries a developer. N1, N2, and N3.

During development, the developing sleeve 8 rotates in the direction of the arrow shown in the figure, and carries the two-component developer whose layer thickness is regulated by the cutting of the magnetic brush by the cutting member 9.
This is transported to a development area facing the photosensitive drum 10, and a developer is supplied to the latent image formed on the photosensitive drum 10 to develop the latent image. At this time, in order to improve the developing efficiency (that is, the rate of applying toner to the latent image), a developing bias voltage in which a DC voltage and an AC voltage are superimposed is applied to the developing sleeve 8 from a power supply.

The ear cutting member 9 is formed of a non-magnetic member such as aluminum, and is disposed upstream of the photosensitive drum 10 in the rotation direction of the developing sleeve 8. Then, the developer (both the non-magnetic toner and the magnetic carrier) passes between the tip of the ear cutting member 9 and the developing sleeve 8 and is sent to the developing area.

By adjusting the gap between the cutting member 9 and the surface of the developing sleeve 8, the amount of the cutting of the developer magnetic brush carried on the developing sleeve 8 is regulated, and the development is transferred to the developing area. The dosage is adjusted.

The first transport screw 5 is arranged substantially parallel to the bottom of the developing chamber 3 along the axial direction (developing width direction) of the developing sleeve 8. In the present embodiment, the first transport screw 5 is made of a ferromagnetic material. A screw structure is provided in which a blade member made of a non-magnetic material is provided in a spiral shape around a rotating shaft, and the rotation causes the developer in the developing chamber 3 to move in the axial direction of the developing sleeve 8 at the bottom of the developing chamber 3. Transport along.

The second transport screw 6 also has a blade member around the rotation axis, like the first transport screw 5.
Takes a screw structure that is provided in a spiral shape in the opposite direction to the transfer screw 5 and is disposed substantially parallel to the first transfer screw 5 at the bottom in the stirring chamber 4 and in the same direction as the first transfer screw 5. And transports the developer in the stirring chamber 4 in a direction opposite to the transport direction of the first transport screw 5.

As described above, by the rotation of the first and second transport screws 5, 6, the developer passes through the openings 11, 12 at both ends of the partition 7, and moves between the developing chamber 3 and the stirring chamber 4. Circulated.

In the present developing apparatus, since the developing chamber 3 and the stirring chamber 4 are arranged vertically, the developer from the developing chamber 3 to the stirring chamber 4 flows downward from the top through the opening 11. Also, the developer from the stirring chamber 4 to the developing chamber 3
It falls from bottom to top through 2. In particular, the developer is delivered from the stirring chamber 4 to the developing chamber 3 so as to be pushed upward from below by the pressure of the developer accumulated at the end.

At this time, as described in the prior art, not all of the developer delivered from the stirring chamber 4 to the developing chamber 3 reaches the downstream end of the first transport screw 5 in the developing chamber 3. Some components are supplied to the developing sleeve 8 on the way, and are collected in the stirring chamber 4 after passing through the developing area. The transfer of the developer to the developing sleeve 8 is performed over substantially the entire width of the developing sleeve 8.

For this reason, the amount of the developer transported by the first transport screw 5 in the developing chamber 3 tends to gradually decrease from the upstream end to the downstream end. On the other hand, the amount of the developer transported by the second transport screw 6 in the stirring chamber 4 tends to gradually increase from the upstream end to the downstream end.

That is, there is a bias in the distribution of the developer in the developing device. In particular, if the amount of the developer in the developing chamber 3 is offset, the supply to the developing sleeve 8 becomes uneven, and the density of the image formed due to the unevenness varies in the axial direction of the developing sleeve 8. Image failure occurs.

Therefore, in this embodiment, the developer is prevented from dropping through the opening 12 to reduce the deviation of the distribution of the developer. This will be described in more detail with reference to FIG. FIG. 3 is a schematic sectional view of the developing device according to the first embodiment of the present invention.

In this embodiment, the circulation of the developer in the developing container is different from that of the conventional example as shown in FIG.

That is, in the developing device according to the present embodiment, the openings 11 and 12 located at both ends of the partition 7 are provided.
Of the developing chamber 3 to block the bottom of the developing chamber 3 immediately before the opening 12 for transferring the developer from the developing chamber 3 to the stirring chamber 4.
3 are provided. This barrier 13 constitutes a suppression mechanism.

As a result, in the present embodiment, there is a portion that becomes higher toward the downstream side of the transport path in the developing chamber 3, and a region that is higher than the bottommost portion of the developing chamber 3 exists in the communicating portion with the stirring chamber 4. This is a feature of the embodiment.

As described above, the developer delivered from the stirring chamber 4 is supplied to the first conveying screw 5 in the developing chamber 3.
Thus, the toner is conveyed while being gradually transferred to the developing sleeve 8, falls through the opening 12 at the downstream end, and circulates to the stirring chamber 4.

Here, in the developing device according to the prior art, almost all of the developer transported to the downstream end of the transport path in the developing chamber falls through the opening into the stirring chamber. The amount of the developer decreases on the downstream side of the developing chamber, and the amount of the developer in the developing chamber is shifted.

On the other hand, in the present embodiment,
A barrier 13 is provided just before the opening 12 provided at the downstream end of the developing chamber 3 so as to block the bottom of the developing chamber 3.
There is a region higher than the bottom of the developing chamber 3 in the communicating portion at the downstream end of the developing chamber 3, and the developer is conveyed slightly upward, so that all the developer conveyed to the downstream end flows into the stirring chamber 4. The developer does not fall and the developer starts to accumulate near the downstream end.

Therefore, the opening 1 from the developing chamber 3 to the stirring chamber 4
The amount of the developer conveyed through the developing chamber 2 can be regulated to a certain amount or less, and a certain amount of the developer can be secured even on the downstream side in the developing chamber where the amount of the developer has been reduced conventionally.
As shown in (1), it is possible to reduce the deviation of the distribution of the amount of the developer in the developing chamber 3.

Incidentally, the degree of deviation of the agent surface can be adjusted by changing the height of the barrier 13 provided immediately before the opening 12.

Further, the barrier 13 provided at the downstream end of the developing chamber does not need to be immediately before the opening 12, but as shown in FIG.
It can be anywhere between

On the other hand, when the developer is disposed in the image area, a developer pool immediately before the wall is formed in the image area, and the density of the image is increased only in that portion, which tends to cause unevenness. However, in this case, the transport screw 5 in the developing chamber 3 and the barrier 13 may come into contact with each other or interfere with each other. However, such a problem may be avoided by making a cut in only that portion or making the screw blade smaller. Can be.

As described above, the bias of the developer in the developing device is reduced, and the supply of the developer to the developing sleeve is performed uniformly in the axial direction, thereby preventing the occurrence of image defects such as density unevenness. It is possible to provide a developing device that can perform the development.

(Second Embodiment) FIG. 4 shows a second embodiment. In the first embodiment,
The structure in which a barrier is provided as the suppression mechanism for suppressing the amount of the developer dropped has been described. In the present embodiment, the case where the amount of the developer dropped is suppressed by reducing the cross-sectional area of the passage of the developer is described. Will be described.

However, by providing a barrier as in the above embodiment, it can be said that the passage of the developer is narrowed. Further, since a part of the passage that blocks a part of the passage in order to narrow the passage can be said to be a barrier, both can be called a barrier. There is no particular distinction.

Since other configurations and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 4 is a schematic sectional view of a developing device according to a second embodiment of the present invention.

In the developing device according to the present embodiment,
On the downstream side of the image area of the developing chamber, the cross-sectional area in the direction perpendicular to the screw axis of the developing chamber is reduced, that is, the area of the developer passage is reduced.

FIG. 4 is a cross-sectional view of a portion having a reduced cross-sectional area in a region A shown on the right end side. In the present embodiment, the diameter of the blade of the screw 5 in the developing chamber 3 is reduced accordingly. As a result, in the region A where the cross-sectional area of the developing chamber 3 is reduced, the transportability of the developer is slightly deteriorated, and the developer starts to accumulate there.

Therefore, the opening 1 from the developing chamber 3 to the stirring chamber 4
2, the amount of the developer conveyed through the developing chamber can be regulated to a certain amount or less, and a certain amount of the developer can be secured even in the downstream side of the developing chamber where the amount of the developer is small, and the distribution of the amount of the developer in the developing chamber can be controlled. It is possible to reduce the deviation.

However, the area A having the reduced cross-sectional area is located on the downstream side of the image area in the developing chamber 3 and has the opening 1
It is preferably up to 2. Because developing room 3
This is because if the amount of the agent changes abruptly in the region where the cross-sectional area becomes small, it may affect the image.

In the downstream area of the developing chamber, the developing chamber 3
May be formed such that the cross-sectional area does not suddenly decrease, but gradually decreases in the downstream direction as shown in FIG. By doing so, it is possible to more reliably prevent the developer surface of the developer from changing abruptly in the area where the cross-sectional area of the developing chamber 3 is reduced, and that this affects the image area.

In the developing device thus obtained, the uneven distribution of the amount of the developer in the developing device is reduced, and the developer is uniformly supplied to the developing sleeve 8 in the axial direction. It is possible to prevent image defects such as density unevenness from occurring.

(Third Embodiment) FIGS. 5 and 6 show a third embodiment of the present invention. In the first embodiment, the configuration in which the barrier is provided as the suppression mechanism for suppressing the amount of the developer dropped has been described.
In the present embodiment, a configuration in which a communicating portion (specifically, an opening) that communicates between the developing chamber and the stirring chamber is provided at a position higher than the bottom surface of the developing chamber to suppress the amount of developer falling. explain.

The other configuration and operation are the same as those of the first embodiment. Therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 5 is a schematic sectional view of a developing device according to the third embodiment of the present invention, and FIG. 6 is a partial perspective view of the developing device according to the third embodiment of the present invention. .

In the present embodiment, the partition 7 between the developing chamber 3 and the stirring chamber 4 extends to the downstream end of the developing chamber 3, and the opening 12 leading to the stirring chamber 4 is located at a position lower than the bottom of the developing chamber 3. It is characterized in that it is provided on the upper side (see FIG. 6).

Since the opening 12 communicating with the agitating chamber 4 from the developing chamber 3 is slightly upward, it communicates with the downstream end, as in the first embodiment. All the developer does not fall into the stirring chamber 4, and the developer starts to accumulate there.

Therefore, the opening 1 from the developing chamber 3 to the stirring chamber 4
2, the amount of the developer conveyed through the developing chamber can be regulated to a certain amount or less, and a certain amount of the developer can be secured even in the downstream side of the developing chamber where the amount of the developer is small, and the distribution of the amount of the developer in the developing chamber can be controlled. It is possible to reduce the deviation.
Note that the degree of deviation of the agent surface can be adjusted by changing the upper and lower positions of the opening 12 provided on the side surface and the width of the opening 12.

The opening 12 on the side of the developing chamber 3 is
As shown in (b), a configuration may be adopted in which the size gradually increases toward the downstream side of the developing chamber, and the degree of deviation of the developer surface may be adjusted. By doing so, the developer surface of the developer changes rapidly,
It can be more reliably prevented that it affects the image area.

In the case where a barrier is provided immediately before the opening as in the first embodiment, the deviation of the developer is adjusted mainly by changing the height of the barrier. In the case where an opening to the stirring chamber is provided on the side surface of the developing chamber as in the embodiment, the position, size (height, width, etc.), shape, and the like of the opening are changed to change the opening in the first embodiment. More fine adjustments can be made in accordance with the configuration of the developing device than in the case.

At this time, by disposing the lower end of the opening 12 above the axial center of the transport screw 5 in the developing chamber 3, the transport screw 5
Can be ensured up to the central axis. As a result, the stirring and conveyance of the developer in the developing chamber 3 and the supply of the developer to the developing sleeve 8 are performed smoothly, and a uniform image without density unevenness can be more stably obtained.

In the developing device thus obtained as well, the bias in the distribution of the amount of the developer in the developing device is reduced, and the developer is uniformly supplied to the developing sleeve 8 in the axial direction. It is possible to prevent image defects such as density unevenness from occurring.

(Fourth Embodiment) In each of the above embodiments, the configuration in which the amount of the developer falling is suppressed by blocking the developer has been described. The configuration in the case where the amount of the developer falling is suppressed by adjusting (1) will be described.

The other configuration is the same as that of each of the above embodiments, and it is sufficient to refer to FIGS. 1 and 2 only. Therefore, description will be made without particularly referring to new drawings.

The present embodiment is characterized in that the transporting force of the transporting member is adjusted downstream of the image area of the developing chamber 3 to reduce the transporting speed of the developer.

When the conveying member is a screw, the conveying force can be adjusted by changing the pitch, size and shape of the blades, the presence or absence of ribs between the blades, and the like.

When the transport speed of the developer is reduced at the downstream end of the developing chamber 3, the developer starts to accumulate there, and the developing chamber 3
The amount of the developer conveyed through the opening 12 to the stirring chamber 4 can be regulated to a certain amount or less.

Therefore, a certain amount of the developer can be secured even on the downstream side in the developing chamber where the amount of the developer is small.
It is possible to reduce the deviation of the distribution of the amount of the developer in the developing chamber 3.

It is to be noted that the transfer force of the transfer member must be adjusted downstream of the image area in the developing chamber. This is because, when the conveying force of the conveying member is changed in the image area, the amount of the developer changes abruptly in the portion where the conveying force has changed, which may cause image defects such as uneven density. is there.

In the developing device thus obtained, the uneven distribution of the amount of the developer in the developing device can be reduced, and the developer can be uniformly supplied to the developing sleeve 8 in the axial direction. It is possible to prevent image defects such as density unevenness from occurring.

(Fifth Embodiment) FIG. 7 shows a fifth embodiment of the present invention. In the above-described first embodiment, a configuration in which a barrier is provided as a suppression mechanism that suppresses the amount of developer falling has been described. However, in the present embodiment, a communication unit ( Specifically, a configuration will be described in which a suction force acts on the developer upward at the opening) to suppress the amount of the developer falling.

The other configuration and operation are the same as those of the first embodiment, so that the same components are denoted by the same reference characters and description thereof is omitted.

FIG. 7 is a schematic sectional view of a developing device according to a fifth embodiment of the present invention.

In the present embodiment, in the developing chamber 3,
Above the opening 12 from the developing chamber 3 to the stirring chamber 4, a magnet 14 as a suction means and a magnetic field generating means is provided.

As a result, the transport screw 5
Is attracted to the upper portion by the magnetic force of the magnet 14 and is attracted to the magnet 14 in the vicinity of the opening 12 downstream of the developing chamber.

The developer adsorbed by the magnet is peeled off by the rotation of a developer screw or the like (not shown) and falls into the stirring chamber.

In such a configuration, since the developer conveyed to the downstream end of the developing chamber receives an upward force due to the magnetic force of the magnet 14, the opening from the developing chamber 3 to the agitating chamber 4 is opened compared with the case without the magnet. It is possible to reduce the amount of developer conveyed through 12.

Therefore, a certain amount of the developer can be secured even on the downstream side in the developing chamber where the amount of the developer is small.
It is possible to reduce the deviation of the distribution of the amount of the developer in the developing chamber.

The degree of deviation of the agent surface can be adjusted by the size, magnetic force, arrangement of magnets, and the like.

In the above description, a magnet has been described as an example of applying a suction force to the developer. However, other than a magnetic field generating means such as an electromagnet, any other means can be used as appropriate.

In the developing chamber, as shown in FIG. 7B, new toner is supplied by toner supply means (not shown) further downstream of the opening 12 from the developing chamber 3 to the stirring chamber 4. In the case of replenishment, if the electromagnet 15 is used, the developer is repeatedly attracted and released by repeating on and off at appropriate intervals, and the toner and the developer replenished in the process are sufficiently separated in the process. mixture·
Stirred.

As a result, it is possible to reduce the effect that the replenished toner is not sufficiently stirred and conveyed to the image area without applying the tribo, thereby affecting the image. It should be noted that the place where new toner is supplied may be anywhere on the downstream side in the transport direction of the image area in the developing chamber. Conversely, when the toner is replenished in the image area, the uncharged toner that is not sufficiently stirred is supplied to that portion, which affects the image such as fog and density unevenness.

In the developing device thus obtained, the uneven distribution of the amount of the developer in the developing device can be reduced, and the developer can be uniformly supplied to the developing sleeve 8 in the axial direction. It is possible to prevent image defects such as density unevenness from occurring.

(Sixth Embodiment) FIG. 8 shows a sixth embodiment of the present invention. In the fifth embodiment, a suction unit is provided above a communication part (specifically, an opening) that connects the developing chamber and the stirring chamber, and a suction force acts on the developer upward. Although the configuration in the case where the amount of the developer dropped is suppressed by performing the above-described operation, in the present embodiment, by providing a suction unit in the communication portion, the suction force similarly acts upward on the developer. The configuration in the case of causing this will be described.

The other configuration and operation are the same as those of the first embodiment, so that the same components are denoted by the same reference characters and description thereof is omitted.

FIG. 8 is a schematic sectional view of a developing device according to a sixth embodiment of the present invention.

In the present embodiment, the developing chamber 3 is connected to the stirring chamber 4
A coil 16, which is a buffer mechanism for the developer that freely falls into the opening 12, is provided so as to wind around the opening 12.

As a result, the transport screw 5
Is gradually dropped into the stirring chamber 4 by the upward magnetic field formed by the coil 16 in the vicinity of the opening 12 downstream of the developing chamber.

Therefore, it is possible to reduce the amount of the developer transported from the developing chamber 3 to the stirring chamber 4 through the opening 12 as compared with the case where the coil 16 is not provided. Therefore, even in the downstream side of the developing chamber where the amount of the developer is small,
It is possible to secure a certain amount of the developer, and it is possible to reduce the deviation of the amount of the developer in the developing chamber.

In this embodiment, as in the case of the fifth embodiment, the replenished toner and developer can be sufficiently mixed and stirred by repeating on and off at appropriate intervals. Is also possible.

In the developing device thus obtained as well, the uneven distribution of the amount of the developer in the developing device is reduced, and the supply of the developer to the developing sleeve 8 is performed uniformly in the axial direction. It is possible to prevent image defects such as density unevenness from occurring.

(Seventh Embodiment) FIG. 9 shows a seventh embodiment of the present invention. In the present embodiment,
A configuration in which a screw (paddle) provided with a paddle is provided in a communication portion (specifically, an opening) that communicates between the developing chamber and the stirring chamber to suppress the amount of developer falling will be described.

The other configuration and operation are the same as those of the first embodiment. Therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 9 is a schematic sectional view of a developing device according to a seventh embodiment of the present invention.

In the present embodiment, the developing chamber 3 is connected to the stirring chamber 4
A paddle 17 which is a mechanism for buffering the developer is provided in the opening 12.

As a result, the transport screw 5
The developer conveyed by the developer falls into the stirring chamber 4 while being suppressed by the rotating paddle 17 near the opening at the downstream of the developing chamber.

Therefore, the amount of the developer transported from the developing chamber 3 to the stirring chamber 4 through the opening 12 can be reduced as compared with the case where the paddle 16 is not provided. Also, in the present embodiment, similarly to the case of the fifth embodiment, the supplied toner and developer can be sufficiently mixed and stirred by the paddle.

In the developing device thus obtained, the uneven distribution of the amount of the developer in the developing device can be reduced, and the developer can be uniformly supplied to the developing sleeve 8 in the axial direction. It is possible to prevent image defects such as density unevenness from occurring.

[0137]

As described above, according to the present invention, the developer conveyed in the developing chamber is provided with the developer carrying member by providing the suppression mechanism for suppressing the amount of the developer falling from the developing chamber to the stirring chamber. Even when the developer is supplied to the developing chamber, the deviation of the amount of the developer in the developing chamber can be reduced, and the image quality can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a developing device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a schematic sectional view of the developing device according to the first embodiment of the present invention.

FIG. 4 is a schematic sectional view of a developing device according to a second embodiment of the present invention.

FIG. 5 is a schematic sectional view of a developing device according to a third embodiment of the present invention.

FIG. 6 is a partial perspective view of a developing device according to a third embodiment of the present invention.

FIG. 7 is a schematic sectional view of a developing device according to a fifth embodiment of the present invention.

FIG. 8 is a schematic sectional view of a developing device according to a sixth embodiment of the present invention.

FIG. 9 is a schematic sectional view of a developing device according to a seventh embodiment of the present invention.

FIG. 10 is a schematic sectional view of a developing device according to a conventional technique.

FIG. 11 is a schematic sectional view of a developing device according to a conventional technique.

FIG. 12 is a schematic sectional view of a developing device according to a conventional technique.

FIG. 13 is a schematic sectional view of a developing device according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developing apparatus 2 Developing container 3 Developing chamber 4 Stirring chamber 5, 6 Screw 7 Partition 8 Developing sleeve 10 Photosensitive drum 11, 12 Opening 13 Barrier 14 Magnet 15 Electromagnet 16 Coil 17 Paddle 22 Light emitting element

Claims (14)

[Claims] 1. A developer carrier for applying a developer to a development area to perform development, a developing chamber for supplying a developer to the developer carrier, and a developer chamber disposed below and adjacent to the developer chamber. A first communicating portion and a second communicating portion communicating with each other near the longitudinal ends of the developing chamber and the stirring chamber. A transport member that transports the developer while agitating the developer is provided. By these transport members, the developer is transported from the agitating chamber to the developing chamber via the first communication unit, and
A developer that supplies developer to the developer carrying member while circulating the developer between the developing chamber and the stirring chamber by dropping the developer from the developing chamber to the stirring chamber via the second communication portion. The developing device according to claim 1, further comprising a suppression mechanism that suppresses an amount of developer falling from a developing chamber to a stirring chamber through the second communication unit. 2. The developing device according to claim 1, wherein said suppressing mechanism has a barrier protruding upward from a bottom surface of said developing chamber. 3. The developing device according to claim 2, wherein the barrier is provided near the second communication portion. 4. The developing device according to claim 1, wherein said suppressing mechanism is configured such that said second communication portion is provided above a bottom surface of said developing chamber. 5. The transfer member provided in the developing chamber is a rotatable transfer screw, and the second communication portion is provided above an axis of a rotation shaft of the transfer screw. The developing device according to claim 4, wherein: 6. The developing device according to claim 1, wherein the suppression mechanism is configured to reduce a transfer capability of a transfer member provided in the developing chamber near the second communication portion. . 7. The transfer member is constituted by a screw having blades, and the transfer capacity is changed by adjusting at least one of the pitch, size, shape, and presence or absence of a rib between the blades. 7. The method according to claim 6, wherein
3. The developing device according to claim 1. 8. The developing device according to claim 1, wherein the suppression mechanism has a suction unit that applies an upward suction force to the developer near the second communication portion. 9. The developing device according to claim 8, wherein said suction means is a magnetic field generating means for applying a magnetic suction force. 10. The developing device according to claim 9, wherein said magnetic field generating means is a magnet provided on a ceiling of a developing chamber. 11. The developing device according to claim 9, wherein said magnetic field generating means is a coil wound so as to surround the second communication portion. 12. The toner according to claim 1, wherein said developer is a two-component developer comprising a toner and a carrier, and a toner supply means for supplying new toner is provided in the vicinity of a magnetic field generated by said magnetic field generating means. Item 12. The developing device according to Item 9, 10 or 11. 13. The developing device according to claim 1, wherein said suppressing mechanism has a screw provided with a paddle which is rotated by a developer passing through the second communication portion. 14. A developing device according to claim 1, wherein said latent image means forms a latent image on the image carrier, and said latent image formed by said latent image means is developed. And an image forming apparatus.