JPH11249426A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of preventing increase of rotational torque and the lowering of developing density with time. SOLUTION: This device is provided with a oblong scraping blade 28 held in contact with a fur brush 22 over the entire area in the axial direction of the fur brush 22, and this scraping blade 28 is disposed in a section parting from a toner feeding port 16. In detail, the blade is disposed on the left end on a separating wall 33 composing the toner feeding port 16 and a toner containing chamber 30 and separating a housing part 14 to the upper and lower sides namely, on the right end of a cover 21 provided at the inlet 30A of the toner containing chamber 30 for protecting the fur brush 22. Then, since the device is always made possible to continuously provide the fresh toner 12 from the toner feeding port 16 to the fur brush 22, the lowering of the developing density can be prevented, and moreover, an ascent of the rotational torque can be restrained as well.

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 an image forming apparatus utilizing an electrophotographic process, such as an electrophotographic copying machine and a printer.

[0002]

2. Description of the Related Art As shown in FIG. 10, a developing device 50 for supplying a toner 12 to a photoreceptor 18 of an image forming apparatus is provided with a fur brush 22. The fur brush 22 is supplied to the developing roller 20 by rotation. Since the fur brush 22 has a fibrous hair surface, if the toner 12 is excessively held on the surface, the toner 12 is gradually pushed into the fur brush 22 by repeated contact with the developing roller 20. Go.

For this reason, the toner 1 is
2 are accumulated, and the toner 12 is
, And the toner 12 is not sufficiently supplied to the developing roller 20. In addition, since the sliding resistance between the developing roller 20 and the fur brush 22 is increased, the rotational torque is increased, and a case where the roller reaches an unrotatable state may occur. Therefore, it is necessary to take care that the amount of toner 12 held by the fur brush 22 does not become excessive.

Therefore, Japanese Patent Publication No.
As shown in JP-A-6-0556529, the contact plate 52 is brought into contact with the fur brush 22, and the toner 12 remaining on the fur brush 22 without being supplied to the developing roller 20 and the fur brush 22 are collected from the developing roller 20. Undeveloped toner 1
In some cases, scraping 2 prevents toner 12 from being pushed into fur brush 22.

However, since the contact plate 52 is disposed near the toner supply port 56, the toner 12 scraped off by the contact plate 52 receives the toner 1 supplied from the toner supply port 56.
2 and cannot be separated from the fur brush 22, and most will be attracted to the fur brush 22 again.

For this reason, the toner 12 once charged is used many times without being neutralized, and the toner 12 on the fur brush 22 and the developing roller 20 is excessively charged while repeating the above operation. Can be The excessively charged toner 12 has an increased adhesion to the developing roller 20, and the photoreceptor 18 (see FIG. 1) with a normal developing bias.
And the development density is lowered as a result.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a developing device that prevents an increase in rotational torque and a decrease in development density over time.

[0008]

According to the first aspect of the present invention, the developer conveyed from the developer supply port of the storage section for storing the developer is supplied to the developing roller by the developer supply means. The developing roller supplies a developer to the photoconductor to develop the latent image. On the other hand, the contact plate is in contact with the developer supply means and scrapes off the developer attached to the developer supply means. Since the contact plate is provided apart from the developer supply port, the developer scraped from the developer supply unit by the contact plate is pushed by the developer conveyed from the developer supply port,
There is no danger that the toner will adhere to the developer supply means again without being separated. For this reason, since fresh developer is always supplied to the developer supply means from the developer supply port, a decrease in the development density can be suppressed, and an increase in the rotational torque can be suppressed.

According to the second aspect of the present invention, the contact plate is provided between the developing roller and the developer supply port.

Therefore, undeveloped developer collected from the developing roller and adhering to the developer supply means can be reliably scraped off.

According to the third aspect of the present invention, the developer accommodating chamber for accommodating the developer scraped off by the contact plate is provided.

In the developer storage chamber, the developer is separated from the developer supply means and stocked, so that the charge is reliably removed. For this reason, the developer is not excessively charged and does not adhere to the developing roller or the developer supply unit more than necessary, so that it is possible to prevent the development density from decreasing over time.

According to the fourth aspect of the present invention, the developer supply means is a fur brush having a large number of fibrous hairs on its surface, and rotates in the same direction as the developing roller.

For this reason, the fur brush rotates in the direction opposite to the developing roller at the contact portion with the developing roller.
The undeveloped developer remaining on the developing roller after the developing roller develops the developer image on the photoconductor can be reliably scraped off.

According to the fifth aspect of the present invention, a communication port is provided for transferring the developer stored in the developer storage chamber to the storage section.

Therefore, the developer scraped off by the scraping plate is naturally conveyed from the developer storage chamber to the storage section through the communication port, so that the space of the developer storage chamber can be reduced.

According to the sixth aspect of the present invention, the transfer assisting member for transferring the developer stored in the developer storage chamber to the storage section is provided.

Therefore, regardless of the shape of the developer accommodating chamber, the discharged developer can be surely returned to the accommodating section and used again, so that the developer is not wasted.

In the invention according to claim 7, the contact plate extends toward the rotation center of the fur brush.

Therefore, when the rotation of the fur brush is stopped, the fibrous hair on the surface of the fur brush does not fall down and is not permanently deformed. Therefore, there is no occurrence of a portion where the fiber density is low and unevenness in density occurs.

According to the eighth aspect of the present invention, there is provided an elastic member which regulates the amount of the developer attached to the surface of the developer supply means in contact with the developer supply means.

As a result, the amount of the developer conveyed from the developer supply means to the developing roller becomes constant, so that the sliding resistance between the developing roller and the developer supply means increases, and the rotational torque increases. Absent.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A developing device according to a first embodiment will be described.

As shown in FIGS. 1 to 3, a storage unit 1 for storing a toner 12 is provided inside a developing device 10 according to the first embodiment.
4, the toner 12 is conveyed to a toner supply port 16 by an auger 15 installed inside the storage section 14.

A fur brush 22 for supplying the toner 12 conveyed to the toner supply port 16 to the developing roller 20 is provided inside the developing device 10. The fur brush 22 has a large number of fibrous hairs 22B on the surface of a shaft 22A.
And is rotatably supported in parallel with the developing roller 20.

Then, the fur brush 22 is connected to the developing roller 2.
0 is slid over the entire area in the axial direction, and the toner 12 carried on the surface is supplied to the developing roller 20.

On the other hand, the developing roller 20 is rotatably supported at a certain interval from the photosensitive member 18. The fur brush 22 and the developing roller 20 rotate in the direction of arrow A.

With the above configuration, the fur brush 22 rotates in the opposite direction at the contact portion with the developing roller 20, and the developing roller 20 develops the toner image on the photoreceptor 18 and remains on the developing roller 20. The toner 12 for development can be reliably scraped off.

The fur brush 22 is provided with a rectangular elastic blade 26 formed of an elastic member.
2, the toner 12 is in contact with almost the entire area in the axial direction, and the amount of the toner 12 attached to the surface is constant.

For this reason, the amount of the toner 12 conveyed from the fur brush 22 to the developing roller 20 becomes constant,
The sliding resistance between the developing roller 20 and the fur brush 22 does not increase and the rotational torque does not increase.

Further, a rectangular scraping plate 28 is in contact with the fur brush 22 over substantially the entire area of the fur brush 22 in the axial direction, and the scraping plate 28 is provided at a position separated from the toner supply port 16. I have. For details,
The fur brush 22 is provided at the left end of the toner supply port 16 and the partition wall 33 constituting the toner storage chamber 30, that is, at the entrance 30A of the toner storage chamber 30.
Is provided at the right end of the cover 21 for protecting the camera.

Therefore, the toner 12 scraped off from the fur brush 22 by the scraping plate 28 is pushed by the toner 12 conveyed from the toner supply port 16 and may adhere to the fur brush 22 again without separating. There is no.
Therefore, since the fresh toner 12 is always supplied to the fur brush 22 from the toner supply port 16, it is possible to suppress a decrease in the development density and an increase in the rotational torque.

Further, since the toner 12 is stored in the toner storage chamber 30 at a distance from the fur brush 22, the charge is reliably removed. Therefore, the toner 12 is not excessively charged and does not adhere to the developing roller 20 or the fur brush 22 more than necessary, so that it is possible to prevent the development density from decreasing with time.

Next, the effect of the developing device according to the first embodiment will be demonstrated. As shown in FIG. 6 to FIG.
A comparison test was performed between the developing device 10 (see FIG. 11) and the developing device 10 according to the first embodiment (see FIG. 1).

As shown in FIG. 6, the development density was compared with the number of developed images. Considering that the density difference in the initial developing density between the conventional developing device 50 and the developing device 10 according to the first embodiment is within the error range of the experiment, the developing density of the conventional developing device 50 decreases as the number of developed images increases. Whereas
It can be seen that the developing device 10 according to the first embodiment does not show a decrease in the developing density even when the number of developed images is 2000. this is,
This indicates that the phenomenon of density reduction when the conventional developing device 50 is used largely depends on the characteristics of the toner 12 that has continued to adhere to the fur brush 22.

Although the developing device 10 according to the first embodiment shows only 2500 sheets on the graph, a satisfactory density could be maintained until the toner 12 disappeared.

Further, in the conventional developing device 50 (see FIG. 7) and the developing device 10 according to the first embodiment (see FIG. 8), the toner transport amount (indicated by a column) and the toner charge distribution (indicated by a bar) Display) was compared. The value of the toner charge distribution indicates the moving distance of the toner 12 with respect to the potential applied at the time of measurement. The larger the value of the toner charge distribution, the more negatively charged the toner 12 is.

Therefore, while the value of the conventional developing device 50 and the value of the developing device 10 according to the first embodiment are almost equal in the amount of transported toner, the value of the toner charge distribution is clearly different from that of the developing device according to the first embodiment. Since 10 is larger, it is understood that the developing device 10 according to the first embodiment can always supply the fresh toner 12. Therefore, the first
The developing device 10 according to the embodiment was able to suppress a decrease in the development density and maintain a substantially constant density from the beginning to the end.

On the other hand, in the conventional developing device 50, since the toner 12 once scraped off by the scraping plate 52 adheres to the fur brush 22 again, the toner 12 is given an excessive charge, 12 does not actively fly to the photoconductor 18. Therefore, the toner 12 that has not been scattered is deposited on the fur brush 22, and only the toner 12 having a reduced charge amount is supplied to the photoconductor 18, and
The toner transport amount is maintained, but the development density is significantly reduced.

Further, as shown in FIG. 9, the shaft torque was compared with the number of developed sheets. The axial torque of each of the developing devices of the developing device 10 according to the first embodiment and the conventional developing device 50 is:
The difference becomes remarkable at 280 sheets. In the conventional developing device 50, the shaft torque increases as the number of developed images increases, whereas in the developing device 10 according to the first embodiment, the shaft torque hardly increases. It can be seen that the toner 12 adhered to the brush 22 has been neatly scraped off.

Due to the characteristics of the toner 12 and the material of the fur brush 22 or the structure of the developing device 10, etc., when the scraped toner 12 is naturally conveyed to the toner storage section 14,
As shown in FIG. 4, a communication port 32 for transporting the toner 12 stored in the toner storage chamber 30 of the developing device 10 according to the first embodiment to the storage unit 14 may be provided. As a result, the toner 12 scraped off by the scraping plate 28 is
Is naturally conveyed to the storage section 14 through the communication port 32, so that the space of the toner storage chamber 31 can be reduced.

The axis of the scraping plate 28 extends toward the center of the fur brush 22. For this reason, when the rotation of the fur brush 22 is stopped,
The fibrous hair 22B on the surface does not fall down and permanently deform. Therefore, there is no occurrence of a portion where the fiber density is low and unevenness in density occurs.

Next, a developing device according to a second embodiment will be described. As shown in FIG. 5, in the second embodiment, the auger 34 is installed in the toner storage chamber 30 described in the first embodiment, and the toner 12 scraped off by the scraping plate 28 is
Transport toward A. Further, the rear side of the partition wall 44 is opened, and from this opening, the standing plate 4 is parallel to the side wall 14A.
5 are provided. An auger 36 is provided between the standing plate 45 and the side wall 14A, and the toner 12 transported by the auger 34 is forcibly supplied to the storage unit 14 again.

For this reason, even when the toner 12 is not naturally conveyed due to the effect of the weight of the toner 12 and the action of the pushing pressure of the toner 12 scraped off from the scraping plate 28, the characteristics of the toner 12, or the configuration of the developing device 46, the force is forced. The toner 12 can be transported to the storage unit 14. Also, the toner storage chamber 30
Irrespective of the shape of the toner, the toner 12 whose charge has been eliminated is securely stored in the storage unit 1.
4 and can be used again.
Need not be wasted.

[0045]

According to the present invention, the above configuration is provided.
According to the invention described in (1), a decrease in the development density can be suppressed, and an increase in the rotational torque can also be suppressed. According to the second aspect of the present invention, the undeveloped developer collected from the developing roller and adhered to the developer supply unit can be reliably scraped off. According to the third aspect of the present invention, the developer is not excessively charged and does not adhere to the developing roller or the developer supply unit more than necessary. According to the fourth aspect of the present invention, the undeveloped developer remaining on the developing roller after the developing roller develops the developer image on the photosensitive member can be reliably scraped off. According to the fifth aspect of the invention, it is possible to reduce the space of the developer accommodating chamber. According to the sixth aspect of the present invention, the developer can be used again, so that the developer is not wasted. According to the seventh aspect of the present invention, there is no occurrence of a portion where the fiber density is low and unevenness in density occurs. According to the eighth aspect of the invention, the amount of the developer conveyed from the developer supply unit to the developing roller is constant.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a developing device according to a first embodiment.

FIG. 2 is an enlarged view showing a scraping plate provided inside the developing device according to the first embodiment.

FIG. 3 is a perspective view showing a scraping plate provided inside the developing device according to the first embodiment.

FIG. 4 is a cross-sectional view illustrating a modification of the developing device according to the first embodiment.

FIG. 5 is a sectional view of a developing device according to a second embodiment.

FIG. 6 is measurement data showing the relationship between the number of developed images and the development density using the developing device according to the first embodiment and a conventional developing device.

FIG. 7 is measurement data showing the relationship between the number of developed sheets, the toner conveyance amount, and the toner charge distribution using a conventional developing device.

FIG. 8 is measurement data showing the relationship between the number of developed sheets, the amount of toner transported, and the toner charge distribution using the developing device according to the first embodiment.

FIG. 9 is measurement data showing the relationship between the number of developed images and the shaft torque using the developing device according to the first embodiment and a conventional developing device.

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

FIG. 11 is an enlarged view showing a scraping plate provided inside a developing device according to a conventional product.

FIG. 12 is a perspective view showing a scraping plate provided inside a developing device according to a conventional product.

[Explanation of symbols]

 Reference Signs List 22 fur brush (developer supply means) 26 elastic blade (elastic member) 28 scraping plate (contact plate) 30 toner storage chamber (developer storage chamber) 32 communication port 34 first auger (transportation auxiliary member) 36 2 augers (transportation assisting members)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiromitsu Koizumi 3-7-1, Fuuchi, Iwatsuki-shi, Saitama Fuji Xerox Co., Ltd. Iwatsuki Office

Claims (8)

[Claims] An accommodating portion for accommodating a developer, a developing roller rotatably supported by a developer supply port of the accommodating portion and supplying a developer to a photoreceptor; A developer supply unit that supplies a developer to the developing roller; and a contact plate that comes into contact with the developer supply unit and scrapes the developer adhered to the developer supply unit. A developing device provided apart from the developer supply port. 2. The developing device according to claim 1, wherein the contact plate is provided between the developing roller and the developer supply port. 3. The developing device according to claim 1, further comprising a developer accommodating chamber for accommodating the developer scraped off by the contact plate. 4. The developing device according to claim 1, wherein said developer supply means is a fur brush having a plurality of fibrous hairs on its surface, and rotates in the same direction as said developing roller. 3. The developing device according to claim 1. 5. The developing device according to claim 3, further comprising a communication port that conveys the developer stored in the developer storage chamber to the storage unit. 6. The developing device according to claim 3, further comprising a transfer assisting member for transferring the developer stored in the developer storage chamber to the storage section. 7. The fur brush according to claim 4, wherein said contact plate extends toward a rotation center of said fur brush.
7. The developing device according to any one of 6. 8. The developing device according to claim 1, further comprising an elastic member that limits an amount of the developer attached to a surface of the developer supply unit in contact with the developer supply unit. apparatus.