JPH06167877A - Developing device - Google Patents

Abstract

PURPOSE:To enhance the stability of the uniformity of a toner concentration in an axial direction by obtaining moderate circulation in the axial direction of a developing roll without impairing the stirring capacity of a developer with a simple constitution. CONSTITUTION:A developer stirring member 15 has low developer movability from the front side of a paper surface toward its inmost side by an asymmetrical blade member 20. A developing stirring member 16 has also the low developer movability from the inmost side of the paper surface toward its front side by an asymmetrical blade member 22. In the developer stirring members 15 and 16, the developer 17 is moderately circulated by these two kinds of reverse flowing, so that the uniformity of the toner concentration can stably be obtained in the axial direction of the developing roll 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device applied to an image forming apparatus for forming an image by an electrostatic recording system such as a copying machine or a printer, and more particularly to a two-component developer containing a mixture of toner and carrier. The present invention relates to a developing device equipped with a stirring means for mixing and stirring.

[0002]

2. Description of the Related Art In a developing device of this type, only toner actually contributes to visualization of an electrostatic latent image.
In the vicinity of the developing roll in the developing container, the amount of toner gradually decreases due to the development, so that the image density decreases.

Therefore, in order to obtain a stable and good image, the toner is appropriately replenished, the replenished toner is quickly dispersed throughout the developer, and the replenished toner is dispersed in the developer roll shaft. It is necessary to provide two points, that is, to uniformly supply the toner in the direction and to improve the circulating property of the developer in the axial direction.

FIG. 6 shows a schematic structure of the developing device disclosed in Japanese Utility Model Laid-Open No. 63-94456. In this developing device, a developing roll 3 is arranged in the developing container 1 so as to face the photosensitive drum 2, and a paddle wheel 4 for feeding the developer 6 to the developing roll 3 and an upper end portion of the developing container 1. A developer stirring member 5 for mixing and stirring the toner replenished from the toner replenishing port 1a provided therein with the developer 6 inside is disposed. Further, on the upper part of the developing roll 3, a developer layer thickness regulating member 7 for regulating the layer thickness of the developer carried on the developing roll 3.
Are arranged.

As shown in FIG. 7, the mixing and stirring member 5 is composed of a rotary shaft 8 and a plurality of elliptical blade members 9 arranged in parallel in the axial direction of the rotary shaft 8.
Each of the plurality of blade members 9 is attached so as to be inclined at a constant angle with respect to the axis of the rotary shaft 8. When the blade member 9 rotates, the blade member 9 conveys the developer occupying one side surface region and the developer occupying the other side surface region in opposite directions. By each of the blade members 9 thus conveying the developer in both axial directions, the developer moves back and forth between the adjacent blade members 9 and, thereby, the developer Mixing and stirring is performed.

In this developing device, toner is supplied from the toner supply port 1a. The toner supplied from the toner replenishing port 1a is conveyed in the paddle wheel 4 direction while being mixed and stirred in the developer by the blade member 9 of the developer stirring member 5, and is supplied to the developing roll 3 by the paddle wheel 4. . Toner is supplied to the photosensitive drum 2 by the developing roll 3 to visualize the electrostatic latent image.

In this developing device, it is possible to obtain a uniform toner concentration by dropping the toner uniformly from the toner supply port 1a in the axial direction of the developing roll 3.

[0008]

However, in this developing device, the developer stirring member 5 has a problem that the mobility of the developer 6 in the axial direction of the developing roll 3 is poor. Therefore, when a large amount of images with uneven images are continuously developed, the toner consumption becomes non-uniform in the axial direction, the uniformity of the toner density is lost, and the development density becomes uneven.

The present invention has been made in view of the above problems, and an object thereof is to obtain a proper circulation property in the axial direction of the developing roll without impairing the stirring ability of the developer with a simple structure. SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device capable of improving the stability of uniformity of toner concentration in the axial direction.

[0010]

SUMMARY OF THE INVENTION A developing device according to the present invention comprises a developer carrying member and a plurality of plate-like members arranged in the axial direction of a rotary shaft arranged parallel to the axial direction of the developer carrying member. The blade members are attached in a tilted manner, and the plate-shaped blade member has an asymmetrical shape with respect to the projection line of the rotary shaft on the plate-shaped blade member, and the developer is moved in one direction along the axial direction of the rotary shaft. And a first developer stirring means having a property,
A second developer stirring means is provided in parallel with the first developer stirring means, and has second developer stirring means having developer movability in a direction opposite to the developer moving direction by the first developer stirring means. ing.

In this developing device, the developer is stirred by the first developer stirring means having the asymmetrical blade member, and the developer moves in one direction along the axis of the rotary shaft. Further, the developer is stirred by the second developer stirring means, and at the same time, the developer is moved in the direction opposite to the developer moving direction by the first developer stirring means. Due to these two flows in the opposite directions, the developer circulates properly in the first and second developer stirring means, and as a result, the uniformity of the toner concentration becomes stable in the axial direction of the developer carrier. can get.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a developing device 1 according to an embodiment of the present invention.
It represents a configuration of 0. This developing device 10 includes a developing roller 1 facing a photosensitive drum 12 in a developing container 11.
3 is arranged, a paddle wheel 14 for feeding a developer 17 composed of toner and a magnetic carrier to the developing roll 13, and the paddle wheel 14
On the other hand, developer agitating members 15 and 16 for delivering the agitated developer 17 are arranged. Developer stirring member 1
5 and the developer stirring member 16 are arranged parallel to each other along the axial direction of the developing roll 13. A developer layer thickness regulating member 18 is arranged above the developing roll 13 to regulate the layer thickness of the developer 17 carried on the developing roll 13 to a predetermined thickness.

FIG. 2 shows the developer stirring member 15 taken out. The developer stirring member 15 includes a rotary shaft 19 that rotates clockwise in FIG. 1 by a drive mechanism (not shown), and a plurality of substantially cross-shaped blade members 20 that are arranged in parallel in the axial direction of the rotary shaft 19. It is configured.
Each of the plurality of blade members 20 is attached at a certain angle with respect to the axis of the rotating shaft 19. The blade member 20 has an asymmetric shape with respect to the projection line 100 of the rotary shaft 19 on the blade member 20, and the asymmetric portion is slightly bent in the direction of arrow a in FIG. It is a bent portion 20a.

When the blade member 20 rotates, it conveys the developer occupying one side surface region and the developer occupying the other side surface region in opposite directions to each other, as in the conventional case. is there. Here, the blade member 20 has a projection line 1
00, the side surface region on the side of the bent portion 20a has a large area and the side surface region on the opposite side has a small area. Therefore, the developer occupying the large-area side surface region has a stronger carrying force than the developer occupying the small-area side surface region, and the developer is mixed and stirred in the entire plurality of blade members 20, In FIG. 1, the developer has weak developer mobility from the front side to the back side (direction of arrow a in FIG. 2). Further, in this embodiment, the asymmetrical portion is the bent portion 20.
Since it is a, this also causes developer mobility in the same direction.

On the other hand, FIG. 3 shows the developer stirring member 16 taken out. The developer stirring member 16 includes a rotary shaft 21 that rotates in a counterclockwise direction in FIG. 1 by a drive mechanism (not shown), and a plurality of substantially cross-shaped blade members 22 that are arranged side by side in the axial direction of the rotary shaft 21. It is composed by. Each of the plurality of blade members 22 is attached at a certain angle with respect to the axis of the rotating shaft 21. Like the blade member 20, the blade member 22 is also asymmetric with respect to the projection line 200 of the rotary shaft 21 on the blade member 22,
The asymmetrical portion is slightly bent in the direction of arrow b in FIG. 3 (front side of the paper in FIG. 1) to form a bent portion 22a.

The developer stirring member 16 has the same shape as the developer stirring member 15, but the mounting direction with respect to the rotating shaft 21 and the rotating direction of the rotating shaft 21 are different from each other. In FIG. 1, the developer has weak developer mobility from the back of the paper to the front side (the direction of arrow b in FIG. 3). Further, since the asymmetrical portion is the bent portion 22a, this also causes the developer mobility in the same direction.

The developing roll 13 is formed of a non-magnetic material into a cylindrical shape and is composed of a developing sleeve 13a rotatable by a motor (not shown) and a magnetic pole magnet 13b fixedly arranged inside the developing sleeve 13a. . A magnetic brush of the two-component developer 17 composed of a magnetic carrier and toner is formed on the surface by the magnetic force of the magnetic pole magnet 13b, and the magnetic brush is rotated by the bias voltage applied to the developing roll 13 and the developing sleeve 13a. Rubbing against the electrostatic latent image formed on the surface of the drum 12,
It is designed to be visualized with toner.

Replenishment toner is supplied from a toner replenishing port 11a provided on the upper surface of the developing container 11 so as to face the developer stirring member 16.

Next, the operation of the developing device 10 of this embodiment will be described.

In the developing device 10, the developer 17 filled in the developing container 11 is conveyed to the developing roll 13 side by the paddle wheel 14. In the developing roller 13, the peripheral developing sleeve 13a rotates in the counterclockwise direction in FIG. 1 to convey the developer 17 to the developing position facing the photosensitive drum 12. The developer 17 on the developing sleeve 13a is regulated to an appropriate thickness by the developer layer thickness regulating member 18, and then has a developing action on the electrostatic latent image formed on the surface of the photosensitive drum 12 at the developing position. This causes the toner in the developer 17 to be consumed. The developer 17 in which the toner has been consumed is returned to the inside of the developing container 11, is carried to the developer stirring member 15 by the paddle wheel 14, and merges with the original developer 17 there.

Here, the developer stirring member 15 has a weak developer mobility from the front side to the back side in FIG. 1 due to the asymmetrical blade member 20. On the other hand, the developer stirring member 16 has weak developer mobility from the back side to the front side in FIG. 1 due to the asymmetrical blade member 22. Therefore, the developer 17 circulates properly in the developer stirring members 15 and 16 by these two flows in the opposite directions, and as a result, the uniformity of the toner concentration is stably obtained in the axial direction of the developing roll 13. Will be done.

The circulation capacity of the developer 17 can be adjusted by changing the size of the bent portions 20a and 22a of the asymmetrical portions of the blade members 20 and 22.

FIG. 4 shows another embodiment of the present invention. The same components as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, a commonly used developer mixing member (blender) 30 is arranged at the center of the developing container 11, and a plurality of paddle wheels 14 for supplying the developer 17 to the developing roll 13 are provided. The blade member 31 is attached.

FIG. 5 shows the internal structure of the paddle wheel 14 in a taken-out manner. A plurality of blade members 31 each have a U-shaped cross-section supporting member 3 whose upper and lower portions are developer transport portions, respectively.
It is supported in an inclined state by 2a and 32b. The blade member 31 has an asymmetrical shape with respect to the line 300 connecting the support members 32a and 32b, and is similar to the blade member 20 of the developer stirring member 15 of the above-described embodiment from the front side to the back side in FIG. Has weak developer mobility.

Therefore, also in this embodiment, the blade member 31 inside the paddle wheel 14 and the developer stirring member 16 are provided.
Rotation of the blade members 22 in opposite directions causes appropriate developer circulation, and similar to the above-described embodiment, the developing roll 13
Thus, the uniformity of the toner density can be stably obtained in the axial direction.

The present invention has been described with reference to the examples.
The present invention is not limited to the above-described embodiments, but can be variously modified without departing from the scope of the invention. For example,
The shape of the asymmetrical blade members 20, 22, 31 is not limited to that of the above-described embodiment, and may be any shape as long as it has developer mobility. Further, in the above embodiment, one developer stirring member 15 is provided so as to be balanced with respect to the developer stirring member 16 having developer movability to one side in the axial direction of the developing roll 13. However, more developer stirring members may be provided, as long as the developer mobility is balanced on both sides in the axial direction.

[0029]

As described above, according to the developing device of the present invention, the first developer stirring means having the asymmetrical blade member provides the developer mobility in one direction along the axial direction of the rotating shaft. In addition to the above, the second developer agitating means provides the developer mobility in the direction opposite to the developer moving direction by the first developer agitating means. The agent circulates in an appropriate amount, which has the effect that the uniformity of the toner concentration can be stably obtained in the axial direction of the developer carrying member.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the configuration of a developing device according to an embodiment of the present invention.

FIG. 2 is a perspective view of one developer stirring member arranged in the developing device of FIG.

3 is a perspective view of the other developer stirring member arranged in the developing device of FIG. 1. FIG.

FIG. 4 is a vertical sectional view showing a configuration of a developing device according to another embodiment of the present invention.

5 is a perspective view showing an internal configuration of a paddle wheel used in the developing device of FIG.

FIG. 6 is a vertical cross-sectional view showing the configuration of a conventional developing device.

FIG. 7 is a perspective view of a developer stirring member arranged in the developing device of FIG.

[Explanation of symbols]

10 ... Developing device, 11 ... Developing container, 12 ... Photosensitive drum (image bearing member), 13 ... Developing roll, 14 ... Paddle wheel, 15, 16 ... Developer stirring member, 17 ... Developer, 18
... developer layer thickness regulating member, 19, 21 ... rotating shaft, 20, 2
2, 31 ... Vane member (asymmetrical type).

Claims (1)

[Claims] 1. A developer carrying member, and a plurality of plate-shaped blade members which are respectively attached at an inclination along an axial direction of a rotary shaft arranged in parallel with an axial direction of the developer carrying member, and A first developer agitation in which the plate-shaped blade member has an asymmetrical shape with respect to the projection line of the rotation shaft on the plate-shaped blade member, and has developer mobility in one direction along the axis of the rotation shaft. And a second developer stirring means that is provided in parallel with the first developer stirring means and has developer movability in a direction opposite to the developer moving direction by the first developer stirring means. And a developing device.