JPH0786716B2 - Development device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developer stirring unit that does not cause image unevenness due to defective circulation of a developer in a developing device using a screw type stirring unit. .

[Conventional technology]

Conventionally, the structure is as shown in FIG. 3, and the developer repeats a circulating movement as shown by an arrow by two stirring screws. On the drive side in the figure, the conveying action by the stirring screw at the bottom of the mag roll is strong, and the developer tends to be reduced at the end. Further, the developer tends to stay on the non-driving side. That is, it was difficult to smoothly move the developer at both ends where the direction of movement of the developer changes.

As shown in FIG. 4, in the image, blurring of the end portion on the driving side and white streaking on the non-driving side occurred.

[Problems to be Solved by the Invention]

In the above-mentioned conventional technique, in the circulating motion of the developer,
The movement of both ends was not smooth, and uneven images were generated due to poor flow.

An object of the present invention is to smooth the flow of the developer at both end portions and to uniformly mix and stir the developer so that a good image can be obtained.

[Means for Solving the Problems]

The above object is achieved by partially cutting the scraper on the side of the screw winding start end of the stirring screw at the lower part of the mag roll, and providing a part of the scraper at the rear end of the conveyance with a discharging means in the circumferential direction.

[Action]

Part of the scraper can improve the suction force of the developer on the exhibiting side, making it less likely to cause scraping at the end, and on the non-driving side, by providing a circumferential fin on the stirring screw, The discharge capacity of can be improved and a smooth circulation movement can be achieved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a vertical sectional view of a developing device adopting the present invention, and FIG. 2 is a horizontal sectional view.

1 is a side plate, 2 is a developing base, and the side plate 1 is screwed to the developing base 2 to form a developing container. Reference numeral 3 is a mag roll, which comprises a fixed magnet roll 3a inside and a sleeve 3b rotatably provided on the outer circumference. Four,
5 is a stirring screen which is a stirring means, and is a shaft 4a,
It is composed by winding screens 4b and 5b around 5a. Reverse winding screws 4c and 5c are provided at the winding ends of the screws 4b and 5b in order to reduce the pressure of the developer 7 on the bearing 6.

For the stirring screen 4 at the bottom of the mag roll 3,
A circumferential fin 4d is partly provided on the outer periphery of the screw 4b on the conveying direction by the 4b, that is, on the opposite drive side in the figure.

A scraper 8 is provided between the mag roll 3 and the stirring screw 4 below the mag roll 3, and is partially cut like a tape 8a on the drive side.

As shown in FIG. 2, the developer 7 moves up and down in accordance with the rotation of the sleeve 3a, and as shown in FIG. By this movement, new developer is supplied to the sleeve 3a.

Further, a scraper 8 is provided in order to improve the replacement of the new and old developers on the sleeve 3a. The scraper 8 also has a function of preventing the scraping pitch of the stirring screen 4 close to the mag roll 3 from affecting the ears of the developer.

In the circulation movement of the developer 7 as described above, as shown in FIG. 2, since the developing base 2 is inclined from the stirring screws 5 to 4, the developer moves from 5 to 4 on the driving side. Is easy to do. However, since the screw 4b of the stirring screw 4 is formed in the vicinity of the side plate 1, the conveying ability at the end is strong and the draft of the developer 7 tends to be lowered at the end. In particular, when the main body is tilted, an image defect is likely to occur as an edge blur on the driving side. In this embodiment, the scraper 8 is provided with a taper cut 8a on the driving side so that the developer 7 at the end portion can be easily sucked up and the change in the draft of the developer 7 can be sufficiently dealt with.

By the way, on the side opposite to the driving side, the developing base 2 is inclined from the stirring screws 5 to 4, so that the developer 7 is reversed.
Was difficult to move. At the end of the stirring screw 4, there is the reverse winding screw 4c, so that the developer 7 easily stays at the end.

For this reason, the developer 7 may have a poor movement, the toner concentration may be locally reduced, and white streaks may occur. In continuous printing with a high blackening rate, the print quality was particularly deteriorated, sometimes leading to carrier pulling.

In this embodiment, as shown in FIG. 1, the fins 4c are provided on the outer circumference of the stirring screw 4 so that the developer can be discharged in the circumferential direction. It was made possible to move smoothly. As a result, it is possible to prevent the developer 7 from staying, achieve a smooth circulating motion, and obtain a uniform image without unevenness.

〔The invention's effect〕

According to the present invention, since the developer can be smoothly circulated, a uniform image without unevenness can be obtained.

[Brief description of drawings]

1 is a vertical sectional view of an embodiment of the present invention, FIG. 2 is a horizontal sectional view of an embodiment of the present invention, FIG. 3 is a vertical sectional view of a conventional example, and FIG. 4 is an image output example of a conventional example. FIG. 1 ... Side plate, 3 ... Mag roll, 4,5 ... Stirring screen, 8
... scraper.

Claims (1)

[Claims] 1. A developer container containing a developer in which a carrier and toner are mixed, a mag roll for conveying the developer in the developer container to an electric latent image surface of a photosensitive drum, and the developer is mixed and stirred. In a developing device provided with a plurality of stirring screws for and a scraper between the mag roll and the stirring screw, a discharging means in the circumferential direction is provided at the winding rear end of the stirring screw under the mag roll in the developer conveying direction. In addition, the scraper is partially cut off at the winding start end side of the stirring screw below the mag roll.