JP4151877B2 - Developing device and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that records an image on a sheet such as a sheet or an OHP film, such as a copying machine, a printer, a facsimile, or a complex machine thereof. In particular, the present invention relates to an electrophotographic image forming apparatus for transferring an image formed on an image carrier by repeating charging, writing, developing, transferring, cleaning, etc. and recording the image on a sheet. In such an electrophotographic image forming apparatus, a one-component developer composed only of toner or a two-component developer composed of toner and carrier is used to develop an electrostatic latent image formed on the surface of the image carrier. The present invention relates to a developing device.
[0002]
[Prior art]
In an electrophotographic image forming apparatus, an electrostatic latent image is formed on an image carrier by charging and writing, and toner is attached by a developing device to develop the electrostatic latent image. Since the developing device consumes toner with use, a replenishing toner container such as a toner bottle and a toner cartridge is provided, and new toner is replenished from the replenishing toner container.
[0003]
For example, as shown in FIG. 7, the developing device includes a developing device 1 and a toner cartridge 2 as a replenishing toner container, and a toner replenishing port 3 of the toner cartridge 2 is connected to a toner replenishing port 4 of the developing device 1. Then, the toner is stirred and conveyed by rotation of the agitators 5 and 6 which are toner stirring members in the toner cartridge 2, and the toner is supplied from the toner cartridge 2 to the developing device 1 through the toner supply ports 3 and 4.
[0004]
Reference numeral 7 in FIG. 7 denotes a toner paddle that is a toner stirring member of the developing device 1. Reference numeral 8 denotes a developer carrying member that attaches toner and develops the electrostatic latent image on the belt-like image carrying member 9.
[0005]
[Problems to be solved by the invention]
However, in such a developing device, there is a possibility that toner is blown out or blocked in the developing device 1 due to excessive toner replenishment from the toner cartridge 2 to the developing device 1.
[0006]
In particular, in a developing device of a quantitative replenishment system that constantly replenishes toner from the toner cartridge 2 to the developing device 1 during image recording regardless of the amount of toner in the developing device 1, such a problem may occur. There was enough.
[0007]
SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to avoid the occurrence of toner blowing or blocking in the developing device due to excessive toner replenishment from the replenishing toner container to the developing device in the developing device of such an image forming apparatus. It is in.
[0008]
A second object of the present invention is to facilitate the connection of the replenishment toner container to the developing device and to easily prevent the toner leakage from the connecting portion in such a developing device.
[0009]
A third object of the present invention is to reliably perform toner replenishment and toner return in such a developing device.
[0010]
The fourth object of the present invention is to clearly distinguish between toner replenishment and toner return in such a developing device.
[0011]
A fifth object of the present invention is to stabilize toner replenishment and toner return by smoothing the flow of toner.
[0012]
A sixth object of the present invention is to provide an image forming apparatus provided with a developing device that achieves the above object.
[0013]
Therefore, the invention described in claim 1 is to achieve the above first to fourth objects.
In the developing device of the image forming apparatus, the toner replenishing port of the replenishing toner container is connected to the toner replenishing port of the developing unit, and the toner is replenished from the replenishing toner container to the developing unit through the toner replenishing port.
One toner passage hole is formed in each of the developing device and the replenishment toner container, and partition plates are provided to divide the toner passage holes into upper and lower parts, respectively. A toner return port for returning toner from the developer to the replenishing toner container, and the toner replenishing port to be on the lower side of the partition plate ,
Each of the partition plates protrudes inward to enter the rotation trajectory of the developing device and the toner stirring member of the replenishment toner container,
The front end of the partition plate of the developing unit is bent downward toward the toner supply port side to form a toner return prevention unit that prevents the toner from returning from the developer unit to the supply toner container through the toner supply port. And
[0018]
According to a second aspect of the present invention, in order to achieve the sixth object, the image forming apparatus includes the developing device according to the first aspect.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall schematic configuration of a color laser printer which is an example of an image forming apparatus.
[0020]
In the printer apparatus main body A of the illustrated color laser printer, an image carrier unit 10 is provided substantially at the center. The image carrier unit 10 is provided with an endless belt-like image carrier 12 that is wound around a plurality of rollers 11. An organic photosensitive layer is formed on the surface of the image carrier 12.
[0021]
Around the image carrier unit 10, a charging unit 14, a writing unit 15, a multi-stage developing unit 16, an intermediate transfer unit 17, a cleaning unit 18 and the like are provided.
[0022]
The charging unit 14 uniformly charges the surface of the image carrier 12 by applying a high voltage.
[0023]
The writing unit 15 emits laser light from a laser diode (not shown) based on a color image signal from a computer, for example, and emits the laser light through a polygon mirror 20, an f / θ lens 21, a plurality of reflection mirrors 22 and the like. Thus, writing corresponding to the image signals of black, cyan, magenta, and yellow is performed to form an electrostatic latent image on the image carrier 12.
[0024]
As shown in FIG. 2 in the illustrated example, the multi-stage developing unit 16 can detachably attach the developing devices 24K, 24C, 24M, and 24Y that store black, cyan, magenta, or yellow developer in order from the bottom. Prepare in multiple stages. Each developing device 24 is selectively brought close to the image carrier 12, and roller-like developer carriers 25 K, 25 C, 25 M, and 25 Y provided in each developing device 24 are in contact with or close to the image carrier 12. .
[0025]
As shown in FIG. 1, the intermediate transfer unit 17 has an intermediate transfer belt 28 that is wound around a plurality of rollers 27. In addition, an intermediate transfer roller 31 is provided around the sheet conveyance path 30, and a cleaning device 32 for the intermediate transfer belt 28 is provided.
[0026]
The cleaning unit 18 for the image carrier 12 presses a cleaning blade against the image carrier 12. Although not shown, the cleaning device 32 for the intermediate transfer belt 28 similarly presses the cleaning blade against the intermediate transfer belt 28.
[0027]
Incidentally, a paper feed cassette 34 is attached to the bottom of the printer apparatus main body A of the laser printer so as to be freely inserted and removed. The sheet in the paper feed cassette 34 is fed out by the rotation of the paper feed roller 35, sent to the sheet transport path 30, transported by the transport roller 36, and timed by the registration roller 37 between the intermediate transfer belt 28 and the intermediate transfer roller 31. Send in towards.
[0028]
A discharge roller 39 is provided downstream of the sheet conveyance path 30 following the fixing unit 38. Further, on the printer apparatus main body A, a paper discharge stack unit 40 for stacking recorded sheets face down is provided.
[0029]
When recording is performed with this laser printer, the rollers 11 and 27 are rotated to rotate and convey the image carrier 12 and the intermediate transfer belt 28 in the directions indicated by the arrows in the drawing, and the sheet feeding roller 35 is rotated to rotate the sheet. Is fed between the intermediate transfer belt 28 and the intermediate transfer roller 31 through the sheet conveyance path 30.
[0030]
On the other hand, the surface of the image carrier 12 is charged by the charging unit 14, and writing is performed by the writing unit 15 to form an electrostatic latent image for each color sequentially on the image carrier 12. Next, toner is electrostatically attached by the multi-stage developing unit 16 and visualized by color. The respective color images are transferred onto the intermediate transfer belt 28 for each color, and four colors are combined to form a color image.
[0031]
The color image formed on the intermediate transfer belt 28 is transferred to a sheet by the intermediate transfer roller 31. After the image is transferred, the transfer image is fixed by the fixing unit 38, and then discharged by the discharge roller 39 onto the discharge stack unit 40 and stacked there.
[0032]
The image carrier 12 after the image transfer is prepared for the next image formation by removing the transfer residual toner with the cleaning blade of the cleaning unit 18. Further, the intermediate transfer belt 28 after image transfer is also prepared for the next image formation by removing the transfer residual toner with the cleaning blade of the cleaning device 32.
[0033]
Incidentally, each developing device 24 includes a developing device 60 and a toner cartridge 62 as shown in detail in FIG. The developing device 60 improves durability and can be used repeatedly by replacing the toner cartridge with a new one when the toner in the toner cartridge 62 runs out.
[0034]
The developing device 60 forms a developing chamber 41 and a toner cartridge storage chamber 43 in the developing case 42. The developing chamber 41 is provided with a roller-like developer carrier 25. The developer carrier 25 faces the image carrier 12 through the development opening 42a of the development case 42, and rotates in the same direction as the image carrier 12 at the opposed position. A roller-shaped developer regulating member 44 is pressed against the developer carrier 25.
[0035]
The developer regulating member 44 is also provided in the developing chamber 41, and as shown in FIG. 4, the shaft 45 is supported by the developing case 42 via the bearing 46, and the bearing 46 is urged by the urging member 47. It is pressed against the carrier 25. Then, it rotates in the counter direction with respect to the developer carrier 25 at the pressing position.
[0036]
As shown in FIG. 3, the tip of the scraping member 48 is pressed against the developer regulating member 44. The scraping member 48 scrapes off the developer attached to the surface of the developer regulating member 44.
[0037]
The developer carrier 25 is also brought into contact with a roller-like developer supply member 50 with a predetermined nip. The developer supply member 50 is also provided in the developing chamber 41 and is made of a foam material 51 such as polyurethane, silicon, EPDM, and polycarbonate, and a metal cored bar 52. The contact position may be in any direction, but in the illustrated example, it rotates in the counter direction with a relative linear velocity difference with respect to the developer carrier 25. A partition table 54 is provided below the developer supply member 50.
[0038]
Further, a toner paddle 56 is provided as a toner agitating member on the back side (left side in the drawing) of the developing chamber 41 to store the developer. The toner paddle 56 has a plurality of blades 56a made of Mylar or the like, and rotates counterclockwise in the drawing.
[0039]
Then, one toner passage hole 42 b is formed in the boundary wall 57 between the developing chamber 41 and the toner cartridge storage chamber 43 of the developing case 42.
[0040]
On the other hand, the toner cartridge 62 is stored in the toner cartridge storage chamber 43 so that it can be pulled out from the front side. The toner cartridge 62 includes two agitators 64 on the left and right sides as toner agitating members in a cartridge case 63, and stores black, cyan, magenta, or yellow toner, respectively. The agitator 64 has a plurality of blades 64a made of Mylar or the like, and may rotate in any direction, but in the illustrated example, both rotate counterclockwise in the figure.
[0041]
The cartridge case 63 is provided with one toner passage hole 63a. When the toner cartridge 62 is installed in the toner cartridge storage chamber 43, the toner passage hole 63a faces the toner passage hole 42b of the boundary wall 57 described above. At this time, the seal member 65 is sandwiched between the peripheral edges of the toner passage hole 63a and the toner passage hole 42b.
[0042]
At the time of image recording, the developer is conveyed while being agitated by the toner paddle 56, drawn onto the partition table 54, and attached to the developer supply member 50. The developer supply member 50 is preliminarily triboelectrically charged by rubbing the developer while rotating, and is supplied to the developer carrying member 25 by coulomb force.
[0043]
The developer carrier 25 carries toner while rotating, and the charged toner is fully charged by friction with the developer regulating member 44 and is thinned by the developer regulating member 44. Then, the thinned toner is attached to the image carrier 12, and the latent image on the image carrier 12 is visualized.
[0044]
In the illustrated example, a belt-shaped image carrier 12 is used. However, if the surface hardness of the developer carrier 25 is kept low, a drum-shaped image carrier 12 can be used.
[0045]
As shown in FIG. 5 in detail, the toner passage hole 42b of the developing device 60 is provided with a partition plate a1 that is integrally formed with the developing case 42 and divides the toner passage hole 42b in the vertical direction. A toner supply port b1 is formed on the lower side, and a toner return port c1 is formed on the upper side. The partition plate a1 protrudes inward to enter the rotation locus of the toner paddle 56, and the tip is bent downward to form a toner return prevention portion d at the tip.
[0046]
On the other hand, the toner passage hole 63a of the toner cartridge 62 is integrally formed with the cartridge case 63, and is provided with a partition plate a2 that divides the toner passage hole 63a up and down, and a toner supply port b2 below the partition plate a2. A toner return port c2 is formed on the upper side. The partition plate a <b> 2 protrudes inward and enters the rotation locus of the agitator 64.
[0047]
During image recording, the agitator 64 is rotated to stir and convey the toner, and the toner is supplied from the toner cartridge 62 to the developing device 60 through the toner supply ports b2 and b1. At this time, the blade 64a of the agitator 64 is applied to the partition plate a2 so that the toner is surely introduced into the toner supply port b2.
[0048]
When the inside of the developing chamber 41 is filled with toner, the toner is returned from the developing device 60 to the toner cartridge 62 through the toner return ports c1 and c2 by the rotation of the toner paddle 56. At this time, the blade 56a of the toner paddle 56 is applied to the partition plate a1 so that the toner is surely introduced into the toner return port c1.
[0049]
At this time, the toner return blocking portion d blocks the toner from returning from the developing device 60 to the toner cartridge 62 through the toner supply ports b1 and b2. As a result, toner replenishment and toner return can be clearly distinguished and performed together.
[0050]
By doing so, it is possible to avoid the occurrence of toner blowing or blocking in the developing device 60 due to excessive toner replenishment from the toner cartridge 62 to the developing device 60.
[0051]
By the way, in the above-described example, the opening area of the toner replenishing port b1 provided in the developing device 60 and the opening area of the toner replenishing port b2 provided in the toner cartridge 62 are substantially equal, and the opening area of the toner return port c1 provided in the developing device 60. And the opening area of the toner return port c2 provided in the toner cartridge 62 is substantially equal.
[0052]
However, as shown in FIG. 6, the opening area of the toner supply port b1 provided in the developing device 60 is larger than the opening area of the toner supply port b2 provided in the toner cartridge 62, and the opening of the toner return port c1 provided in the developing device 60. The opening area of the toner return port c2 provided in the toner cartridge 62 may be formed larger than the area.
[0053]
In this way, the toner flow can be smoothed and toner replenishment and toner return can be stabilized. In FIG. 6, the reference numerals used for the corresponding parts in FIG. 5 are used as they are.
[0054]
In the above-described example, each of the developing device 60 and the toner cartridge 62 is formed with one toner passage hole 42b / 63a, and the partition plates a1 and a2 that divide the toner passage hole 42b and 63a vertically are provided. The toner supply ports b1 and b2 and the toner return ports c1 and c2 are formed in the toner passage holes 42b and 63a by the partition plates a1 and a2, respectively.
[0055]
As a result, when the toner cartridge 62 is connected to the developing device 60, it is only necessary to match each one of the toner passage holes 42b and 63a, and it is only necessary to seal the periphery of the toner cartridge 62. Therefore, toner leakage from the connecting portion is easy. Can be prevented.
[0056]
Of course, the toner replenishing port b1 and the toner return port c1 are not formed by partitioning one toner passage hole 42b, and the toner supply port b2 and the toner return port c2 are formed by partitioning one toner passage hole 63a. Instead, the toner supply port b1 and the toner return port c1 may be provided separately in the developing device 60, and the toner supply port b2 and the toner return port c2 may be provided separately in the toner cartridge 62. You may make it provide in.
[0057]
In the above-described example, the case where the box-type toner cartridge 62 is used as the replenishment toner container has been described. However, the replenishment toner container is not limited to a box shape, and may be a bottle-shaped toner bottle, for example.
[0058]
Furthermore, in the above-described example, the case where the present invention is applied to a color laser printer which is an example of an image forming apparatus has been described. However, the present invention is not limited to a color, is not limited to a laser printer, and is not limited to a printer. Of course, the present invention can be applied to other image forming apparatuses.
[0059]
【The invention's effect】
As described above, according to the present invention, since the toner return port for returning the toner from the developing device to the replenishing toner container is formed in the developing device and the replenishing toner container, when the developing chamber becomes full of toner, the toner returning port is formed. By returning the toner from the developing device to the replenishing toner container through the opening, it is possible to avoid the occurrence of toner blowing or blocking in the developing device due to excessive toner replenishment from the replenishing toner container to the developing device.
[0060]
According to the first aspect of the present invention, one toner passage hole is formed in each of the developing device and the replenishing toner container, and the partition plates that divide the toner passage hole in the vertical direction are provided. Since a toner replenishing port and a toner return port are formed in the toner passage hole, when connecting the replenishment toner container to the developing unit, it is only necessary to match each one toner passage hole, and only to seal around it. The toner leakage from the connecting portion can be easily prevented.
[0061]
Further, according to the invention of claim 1, since projects the partition plate to each inward to enter during the rotation locus of the toner stirring member of the developing device and toner replenishment container, the partition plate of the toner agitating member of the toner replenishment container The toner can be reliably introduced into the toner replenishing port, and the toner stirring member of the developing device can be applied to the partition plate to reliably introduce the toner into the toner return port.
[0062]
Furthermore, according to the first aspect of the present invention, the tip of the partition plate of the developing device is bent to form a toner return preventing portion that prevents the toner from returning from the developing device to the supply toner container through the toner supply port. Then, the toner return blocking portion blocks the toner from returning from the developing device to the supply toner container through the toner supply port, and the toner supply and the toner return can be clearly distinguished and performed together.
[0064]
According to the second aspect of the present invention, since the developing device according to the first aspect is provided, an image forming apparatus including the developing device having the above effects can be provided.
[Brief description of the drawings]
FIG. 1 is an overall schematic configuration diagram of a color laser printer as an example of an image forming apparatus.
FIG. 2 is a schematic configuration diagram of a multi-stage developing unit provided in the color laser printer.
FIG. 3 is a schematic configuration diagram of one developing device used in the multi-stage developing unit.
FIG. 4 is a view showing a state in which the developer regulating member is pressed against the developer carrying member in the developing device.
FIG. 5 is a partially enlarged view of the vicinity of the toner passage hole of the developing device.
FIG. 6 is a partially enlarged view of the vicinity of a toner passage hole of another example.
FIG. 7 is a schematic longitudinal sectional view of a conventional developing device.
[Explanation of symbols]
16 Multi-stage developing unit 24 Developing device 41 Developing chamber 42 Developing case 42b Toner passage hole 56 of developing device Toner paddle (toner stirring member of developing device)
56a Toner paddle blade 60 Developer 62 Toner cartridge (replenishment toner container)
63 Cartridge case 63a Toner passage hole 64 of toner cartridge Agitator (toner stirring member of toner cartridge)
64a Agitator blades a1 Developer partition plate a2 Toner cartridge partition plate b1 Toner supply port b2 Toner cartridge toner supply port c1 Developer toner return port c2 Toner cartridge toner return port d Toner return blocking portion

Claims (2)

In the developing device of the image forming apparatus, the toner replenishing port of the replenishing toner container is connected to the toner replenishing port of the developing device, and the toner is replenished from the replenishing toner container to the developing device through the toner replenishing port.
One toner passage hole is formed in each of the developing device and the replenishment toner container, and a partition plate for dividing the toner passage hole into upper and lower portions is provided, and the toner replenishment port is provided in each toner passage hole by the partition plate. And, conversely, forming a toner return port for returning the toner from the developing device to the replenishment toner container so that the toner replenishment port is on the lower side of the partition plate ,
Each of the partition plates protrudes inward to enter the rotation locus of the developing unit and a toner stirring member of the replenishment toner container;
A tip of the partition plate of the developing unit is bent downward toward the toner supply port side to form a toner return prevention unit that prevents the toner from returning from the developer to the supply toner container through the toner supply port. A developing device. An image forming apparatus comprising the developing device according to claim 1.

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