JPH06301286A - Developing device - Google Patents

Abstract

PURPOSE:To balance the carrying quantity of a developer in the axial direction of a developer carrying screw member and to obtain an image difficult to generate a density gradient by carrying the developer toward the center in the axial direction from both end sides of the developer carrying screw member. CONSTITUTION:A part of the developer on the left end side of a cylindrical member 12 enters the cylindrical member 12 and is carried toward the other end part side of the cylindrical member 12 in the direction of the broken line, by an internal developer carrying screw member 13. Further, a part of the developer is carried toward the center in the axial direction of the cylindrical member 12 by a first external developer carrying screw member 14. On the other hand, the developer carried by the internal developer carrying screw member 13 and flowing out of the right end part of the cylindrical member 12 is infiltrated to its peripheral side and carried toward the center in the axial direction of the cylindrical member 12 by a second external developer carrying screw member 15. When the developer is carried like this, the flocculated developer is broken up and uniformly supplied to a developer supplying member.

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 an electrostatic latent image formed on a latent image carrier with a developer.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer or a facsimile, which forms an electrostatic latent image on a latent image carrier, a dry type powder developer is used to visualize the latent image. Type developing device is widely adopted. Figure 5
1 shows a schematic configuration of a conventional example of such a developing device.

The developing device 1 in this figure has a developing casing 2 which is the main body of the device. Inside the casing, a toner to which an auxiliary agent is added as needed, that is, a one-component developer ( Hereinafter, it will be simply referred to as a developer) 3.

Inside the developing casing 2, a roller-shaped developer carrying and conveying rotary member 5 is provided, which is opposed to a drum-shaped photosensitive member 4 which is one constitutional example of the latent image carrier. The roller-shaped developer carrying / conveying / rotating member 5 is generally called a “developing roller”, but the present invention is also applicable to a developing device using a belt-like developer carrying / conveying / rotating member. A roller-shaped developer supplying member 6 made of, for example, a soft elastic body is provided inside the developing casing 2, and the developer supplying member 6 is juxtaposed so as to be adjacent to the developer carrying and conveying rotary member 5. Further, inside the developing casing 2, a developer conveying screw member 7 is provided, which is juxtaposed so as to be adjacent to the developer supplying member 6.

Each of the members 5, 6 and 7 is rotatably supported by the side wall portion (not shown) of the developing casing 2 at both shaft portions thereof.
Each is, for example, driven to rotate in the direction of the arrow shown. Further, the photosensitive member 4 is also rotationally driven in the direction of the arrow in the figure so that the portion facing the developer carrying and conveying rotating member 5 moves in the same direction as the developer carrying and carrying rotating member, for example. .

The developer supply member 6 rotates so as to rub against the developer carrying and conveying rotating member 5, and at this time, the developer 3 is carried and carried by the friction with the developer carrying and conveying rotating member 5. It is electrostatically supplied and supported on the outer peripheral surface of the member 5.
The developer 3 carried on the developer carrying and conveying rotary member 5 is carried by the rotation of the rotary member 5,
While being thinned by the developer thinning blade 8, the electrostatic latent image formed on the photoconductor 4 is visualized in the developing region facing the photoconductor 4.

By the way, in this type of developing device,
In order to loosen the aggregated developer, the developer 3 is conveyed in the axial direction of the developer supply member 6 and stirred in the developing casing 2. The developer-conveying screw member 7 conveys the developer 3 in the axial direction thereof, and in this conveying stage, the developer conveying screw member 7 functions to supply the developer supplying member 6 while loosening the aggregated developer.

FIG. 6 is a view of the developer carrying screw member 7 of FIG. 5 seen from the direction of arrow A. In this figure,
The developer is dropped in the direction of arrow B from a developer cartridge (not shown) or the like, and is housed in the developing casing 2.
When the developer carrying screw member 7 rotates, the developer 3 in the developing casing 2 is carried in the direction of arrow C from one end side of the developer carrying screw member 7 toward the other end side. During this conveyance, the cohesive developer is loosened and supplied to the developer supply member 6.

In such a conventional developing device, the developer is conveyed by the developer conveying screw member 7 only in one longitudinal direction (axial direction).
It takes time for the developer to reach the other end, and therefore, for example, when a full-face solid image is output, the image output next may be an image with a density gradient. In this way, the rise of the developer amount after the solid image is output is delayed, and a density gradient is formed in the next image.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to convey a developer in two directions from both ends of the developer conveying screw member toward the axial center of the developer conveying screw member. It is an object of the present invention to provide a developing device capable of achieving an image in which a density gradient is less likely to occur by balancing the developer transport amount in the axial direction.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a developer, which is opposed to a latent image bearing member and visualizes an electrostatic latent image on the latent image bearing member, on an outer peripheral surface thereof. The developer carrying and conveying rotating member that carries and conveys the developer and the developer carrying and conveying rotating member juxtaposed to each other. The friction between the developer carrying and conveying rotating member electrostatically transfers the developer onto the developer carrying and conveying rotating member. A developer supply member to be supplied and carried, and a developer conveying screw member which is arranged in parallel with the developer supply member and which supplies the developer to the developer supply member while conveying the developer in the axial direction of the developer supply member. , A developer-conveying screw member among them, a cylindrical member, and an internal developer conveyer which is provided inside thereof and conveys the developer on one end side of the cylindrical member toward the other end side inside thereof. The screw member and the tubular member are provided around the tubular member. A first external developer conveying screw member that conveys the developer on one end side of the material to the outside of the cylindrical member toward the center of the cylindrical member axial direction, and the first external developer conveying screw member that is also provided around the cylindrical member and The present invention proposes a developing device including a second external developer conveying screw member that conveys the developer conveyed to the other end side toward the center of the cylindrical member axial direction outside the cylindrical member.

An internal developer conveying screw member,
It is effective that the first and second external developer carrying screw members are integrally formed with the tubular member.

Further, it is effective that any one of the internal developer carrying screw member and the first and second external developer carrying screw members is integrated with the tubular member.

Further, an internal developer conveying screw member,
It is effective that the first and second external developer carrying screw members are driven to rotate independently of each other.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. In this description, the same reference numerals are used for members that achieve the same functions as those of the conventional example,
Here, the description of the function is omitted.

FIG. 1 shows a schematic structure of a developer carrying screw member provided in a developing device according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the developing device 10 according to one embodiment of the present invention. Members other than the developer carrying screw member 11 shown in this drawing are constructed in the same manner as the conventional one. . FIG. 1 shows the developer conveying screw member 11 of FIG.
FIG. 3 is a schematic view of FIG.

In FIGS. 1 and 2, the developer carrying screw member 11 includes a cylindrical member 12 having a circular outer peripheral surface,
An internal developer conveying screw member 13 provided inside this for conveying the developer (one-component developer) 3 on one end side of the tubular member 12 toward the other end side therein.
A first external developer carrying screw member 14 which is provided around the tubular member 12 and carries the developer 3 on one end side of the tubular member 12 toward the center of the tubular member axial direction outside the tubular member. A second external device that is also provided around the tubular member 12 and that transports the developer 3 transported to the other end portion side of the tubular member 12 toward the axial center of the tubular member outside the tubular member. The developer conveying screw member 15 is mainly included.

FIG. 3 is a schematic perspective view showing a part of the developer carrying screw member 11. In FIG. 3, the second external developer carrying screw member 15 has a first external developer carrying screw. In order to distinguish it from the member 14,
For convenience, it is shown by a broken line (the same applies to FIG. 4).

Returning to FIG. 1, when there is no developer in the developing casing 2 or when there is little developer in the developing casing, the developer is replenished from the developer cartridge 16 and one end portion of the cylindrical member 12 is replenished. It is stored on the side (the left end side in FIG. 1).

In this state, the tubular member 12, the internal developer carrying screw member 13, and the first and second external developer carrying screw members 14 and 15 are integrally formed in FIG. 2 in the clockwise direction. When the developer 3 rotates, the developer 3 is conveyed along the arrow direction shown in FIG.

That is, a part of the developer on the left end side of the cylindrical member 12 is part of the internal developer carrying screw member 1.
3 enters the inside of the tubular member 12, and in the direction of the broken line,
The cylindrical member 12 is conveyed toward the other end side (right end side in FIG. 1). Further, a part of the developer is carried by the first external developer carrying screw member 14 toward the axial center of the tubular member 12 outside the tubular member 12. On the other hand, the developer carried by the internal developer carrying screw member 13 and coming out from the right end portion of the tubular member 12 wraps around the peripheral surface side of the tubular member 12 to form the second external developer carrying screw. The member 15 conveys it outside the tubular member 12 toward the axial center of the tubular member 12. When the developer 3 is conveyed in this manner, the cohesive developer is loosened and uniformly supplied to the developer supply member 6.

In the conventional developing device, when the developer amount becomes large on the right end side of the developer conveying screw member,
Although the image density tends to be high on this side and low on the opposite side, in this example, the developer sent to the right end side is positively sent toward the axial center of the tubular member 12. Therefore, it is possible to obtain an image in which such a density gradient is less likely to appear.

An internal developer carrying screw member 13 and first and second external developer carrying screw members 14,
As shown in FIG. 2, the reference numeral 15 is appropriately constituted by a spiral blade that is often used in a screw conveyor or the like, or a wire wound in a coil shape.

If it takes a long time for the developer that has entered the inside of the cylindrical member 12 to come out of the outside of the cylindrical member 12 and reach the center thereof, the internal developer conveying screw member 13 is used. By rotating the external developer transport screw members 14 and 15 relatively faster, such time can be shortened.

In any case, by adopting the developer conveying screw member having the structure shown in FIG. 1, the rising time until the image without the density gradient is obtained after the output of the full solid image, It can be shortened.

As described above, when the developer carrying screw member 11 of this example is used, the developer can be supplied in a good balance in the axial direction. In other words, it is possible to supply the developer in a well-balanced manner over the entire developing width (the width in the axial direction in which the developer carrying and conveying rotary member 5 faces the photoconductor 4), and moreover, the supply can be performed quickly. Of. At the same time, the cohesive developer can be loosened at the same time.

In the conventional example shown in FIG. 5, two developer conveying screw members 7 may be prepared, and these may be arranged side by side in the horizontal direction to change the respective feeding directions. As a result, the width of the developing device becomes large, and a density gradient is generated due to the developer conveying screw member on the side in contact with the developer supply member 6.

Further, if two developer conveying screw members 7 are similarly arranged vertically, the height of the developing device is increased, and similarly, the developer on the side in contact with the developer supplying member 6 is also increased. A concentration gradient is generated due to the transport screw member. In the case of this example, since it is not necessary to configure a plurality of developer conveying screw members in parallel, it is possible to further reduce the size of the developing device.

When the internal developer carrying screw member 13 and the first and second external developer carrying screw members 14 and 15 shown in FIGS. 1 and 3 are integrated with the tubular member 12, respectively, A single driving source is sufficient as the driving means for the developer conveying screw member 11, and further cost reduction and space saving can be achieved.
It is possible to increase the flexibility of the device layout within the machine body.

On the other hand, if the internal developer carrying screw member 13 and the first and second external developer carrying screw members 14 and 15 are independent of each other and are independently driven to rotate, By changing the number of rotations of each of them or controlling the rotations thereof appropriately to be turned on and off, it is possible to delicately change the carry amount of the developer 3.

For example, in FIG. 1, when it is detected by a sensor (not shown) that the developer amount at the position corresponding to the right end side of the cylindrical member 12 is too large, the internal developer conveying screw member 13 is stopped. Thus, the amount of developer 3 conveyed in that direction is suppressed. When the sensor detects that the developer is excessively concentrated in the central portion, both external developer conveying screw members 14 and 15 are stopped to suppress the conveying amount of the developer 3 toward the central portion. In any case, the supply amount of the developer 3 can be adjusted so that the supply amount of the developer 3 is balanced in the developing width direction.

Further, the internal developer conveying screw member 13
And the first and second external developer conveying screw members 1
Either one of 4, 4 and 15 can be integrated with the tubular member 12.

FIG. 4 shows an external developer carrying screw member 1
4 and 15 are composed of a spiral wire, and this is a connecting piece 1
An example of a developer carrying screw member integrally formed with the tubular member 12 by 7 will be described. In this developer carrying screw member 21, the cylindrical member 12 and the internal developer carrying screw member 13 are independently driven to rotate. In this example, it is not necessary to assemble the external developer carrying screw members 14 and 15 to the tubular member 12 by screwing them, and the position adjustment work of the external developer carrying screw member (external developer carrying screw member) is performed. Position adjustment work in the radial and axial directions) is not required. Further, since the connecting piece 17 functions to separate the developer 3 (FIG. 2) during the transport of the developer, the effect of preventing the aggregation can be enhanced.

The internal developer carrying screw member 13 may be integrated with the tubular member 12, and both external developer carrying screw members 14 and 15 may be independent of the tubular member 12. It is possible to subtly change the supply amount of.

[0036]

According to the developing device of the first aspect, the developer can be supplied in a well-balanced manner in the developing width direction.
It is possible to obtain a high quality image with a small density gradient.
Further, since it is not necessary to install a plurality of developer conveying screw members in parallel, the developing device can be made smaller and more compact.

According to the developing device of the second aspect, since a single driving source is sufficient as the driving means for the developer conveying screw member, the cost and space of the developing device can be further reduced.

According to the developing device of the third aspect, it is not necessary to position the internal developer carrying screw member or the external developer carrying screw member with respect to the cylindrical member, and to mount the same.

According to the developing device of the fourth aspect, the supply amount of the developer in the developing width direction can be slightly changed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a developer carrying screw member included in a developing device according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a developing device according to an embodiment of the present invention.

FIG. 3 is a partial perspective view of a developer transport screw member.

FIG. 4 is a perspective view of a part of a developer carrying screw member of another example.

FIG. 5 is a partial cross-sectional view of a conventional developing device.

FIG. 6 is a schematic configuration diagram of a developer conveying screw member provided in the same developing device.

[Explanation of symbols]

 3 Developer 4 Drum-Shaped Photoreceptor as Latent Image Carrier 5 Developer-carrying Conveying Rotating Member 6 Developer Supplying Member 10 Developing Device 11 Developer Conveying Screw Member 12 Cylindrical Member 13 Internal Developer Conveying Screw Member 14 External Developer Conveying screw member 15 External developer conveying screw member 21 Developer conveying screw member

Front Page Continuation (72) Inventor Noriyuki Kimura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Katsuhiro Aoki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Shinichi Nakakata 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd. (72) Inventor Chiyako Hatsuyama 1-3-3 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd.

Claims (4)

[Claims] 1. A developer-carrying / conveying rotary member, which is arranged opposite to a latent image carrier and carries a developer for visualizing an electrostatic latent image on the latent image carrier, and carries the developer on an outer peripheral surface thereof, and A developer supply member which is juxtaposed to the developer carrying and conveying rotary member and electrostatically supplies and carries the developer onto the developer carrying and conveying rotary member by friction with the developer carrying and conveying rotary member, and to the developer supplying member. A developer feeding screw member that is arranged in parallel and that feeds the developer to the developer feeding member while feeding the developer in the axial direction of the developer feeding member, wherein the developer feeding screw member is a tubular member. , An internal developer conveying screw member which is provided inside this and conveys the developer on one end side of the tubular member toward the other end side inside thereof, and a tubular member provided around the tubular member. The developer on one end side of the member is placed outside the tubular member. A first external developer conveying screw member that conveys the developer toward the center in the axial direction, and a developer that is provided around the cylindrical member and is conveyed to the other end of the cylindrical member outside the cylindrical member. And a second external developer conveying screw member that conveys the sheet-shaped member toward the center in the axial direction. 2. An internal developer carrying screw member, and a first
The developing device according to claim 1, wherein the second external developer conveying screw member and the second external developer conveying screw member are integrally formed with the tubular member. 3. An internal developer carrying screw member, and a first member.
The developing device according to claim 1, wherein any one of the second external developer conveying screw member and the second external developer conveying screw member is integrated with the tubular member. 4. An internal developer carrying screw member, and a first member.
The developing device according to claim 1, wherein the developing device and the second external developer carrying screw member are independently driven to rotate.