JPH06208302A - Developing device - Google Patents

Abstract

PURPOSE:To exhaustively discharge developer to the outside of a developing tank. CONSTITUTION:A rotating body 25 is arranged on the extension 42 of a line linking a part P1 where magnetic force does not exist between the release pole S2 and the lifting pole S3 of a developing roller 22 with the center 0 of the roller 22. The wall surface 45 of the developing tank 21 between the rotating body 25 and the roller 22 is formed in parallel with the extension 42 of that line. In the case the developer is discharged, it is separated from the roller 22 at the part P1 where the magnetic force does not exist on the roller 22. The dropped developer butts against the wall surface 45 of the tank 21. The developer drops along the wall surface 45 and is gathered to the rotating body 25. The developer in the tank 21 is exhaustively discharged from an exhaust port 24 by the rotating body 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for discharging a developer in a developing tank in a developing device of an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art A conventional developing device (Japanese Patent Laid-Open No. 60-1403).
No. 68), as shown in FIG. 6, 1 is a developing tank, 2 is a developing roller, 3 is a stirring roller, 4 is a hopper casing,
5 is an opening, 6 is a shutter, 7 is a cartridge, 8 is a photo sensor for detecting the cartridge, 9 is a discharge screw, 10 is a collection bottle, 11 is a sensor for detecting the presence or absence of the developer in the bottle 10, and 12 is It is a discrimination gate of the output signal of the sensor 11.

When collecting the developer in the developing tank 1, the waste developer is collected in the collecting bottle 10 by the discharge screw 9 provided in the developing tank 1.

[0004]

However, in the conventional developing device, the discharge screw 9 is located farthest from the developing roller 2 and is disposed on the side of the stirring roller 3, so that the developer is collected. When doing so, there is a problem that the developer in the developing tank 1 is not completely discharged and remains at the bottom of the developing tank 1.

For this reason, the developer which could not be discharged had to be discharged manually by a service person.

In view of the above, it is an object of the present invention to provide a developing device for discharging the developer in the developing tank to the outside of the developing tank without exhaustion.

[0007]

According to a first aspect of the present invention, there is provided a developing tank 21 in which a developing roller 22 and an agitating roller 23 are rotatably mounted, and a developer discharge port is provided at the bottom of the developing tank 21. 24 is formed to discharge the developer 24
In the developing device provided with the rotating body 25 for discharging the toner from the developing tank 21 to the outside of the developing tank 21,
It is arranged in a range surrounded by the release pole S2 and the lifting pole S3, which have the same pole.

According to a second aspect of the present invention, the means for solving the problem is the rotating body 2
The position 5 is located under the developing tank 21, and the magnetic poles of the developing roller 22 are set so that the space between the release pole S2 and the lifting pole S3 of the developing roller 22 faces downward.

According to a third aspect of the present invention, the means for solving the problem is the rotating body 2
5 is on a straight extension line 42 connecting the center point P1 at which the magnetic force between the release pole S2 and the lifting pole S3 of the developing roller 22 disappears and the axial center O of the developing roller 22, or the extension line 4
2 and a perpendicular line 50 drawn from the shaft center O of the developing roller 22 or within the range and below an outer diameter tangent line 51 connecting the developing roller 22 and the stirring roller 23. Is.

[0010]

In the means for solving the problems according to the above-mentioned claim 1, when the developer is stirred and discharged, the developer on the developing roller 22 falls onto the rotary member 25, the developer is stirred, and the developer is released when discharged. Is efficiently conveyed and discharged.

In the means for solving the problem according to claim 2, the developer on the developing roller 22 is separated from the vicinity of the point P1 between the release pole S2 and the lifting pole S3 which are set downward, and the rotary body 2
5, the developer is surely collected.

In the problem solving means according to the third aspect, when the developer is agitated and discharged, the developer on the developing roller 22 has a releasing pole S2 and a lifting pole S3 of the developing roller 22.
Developing roller 22 near the portion P1 where the magnetic force between
And falls on the rotating body 25. Then, the developer concentrates on the rotating body 25 and can be effectively collected. Moreover, the released developer moves along the outer diameter tangent line 51 and is sequentially conveyed and discharged without being disturbed by the outer diameter of the rotating body 25.

[0013]

【Example】

(First Embodiment) FIG. 1 is a block diagram of a developing device showing a first embodiment of the present invention, FIG. 2 is a sectional view of the developing device, and FIG. 3 is a diagram showing a magnetic force distribution on the surface of the developing roller.

The developing device of this embodiment is as shown in FIGS.
A developing roller 22 and an agitating roller 23 are rotatably incorporated in the developing tank 21, a developer discharge port 24 is formed at the bottom of the developing tank 21, and the developer is discharged from the discharge port 24 to the developing tank 21.
A rotating body 25 is provided for discharging to the outside.

The developing roller 22 is disposed so as to face the photoconductor 26, is fixed to the developing tank 21, and magnetically attracts the developer to form a magnetic brush. It consists of a loosely fitted sleeve.

The magnet body adsorbs the developer conveyed from the agitating roller 23 and lifts it up.
And carrier poles N2 and S1 for carrying the developer to the photoconductor 26 side.
From the main developing electrode N1 for adhering toner to the latent image formed on the photoconductor 26, and the release electrode S2 for returning the developer remaining without being transferred to the photoconductor 26 into the developing tank 21. It is configured and has the magnetic force distribution shown in FIG.

The lifting pole S3 is arranged at a position facing the agitating roller 23, the developing main pole N1 is arranged facing the photoconductor 26 on the downstream side in the rotation direction of the lifting pole S3, and the releasing pole S2 is It is arranged on the downstream side in the rotational direction of the main developing electrode N1. The lifting pole S3 and the developing main pole N1 have opposite polarities, and the lifting pole S3 and the release pole S2 have the same polarity and a zero gauss region exists between both poles.

A doctor 27 is attached above the developing roller 22 of the developing tank 21.
A flow plate 28 is arranged above the gap between the stirring roller 23 and the stirring roller 23, and the developer scraped off by the doctor 27 is used as the flow plate 2.
It sends to the direction of the stirring roller 23 via 8.

A toner replenishing tank 29 is mounted on the upper part of the developing tank 21 on the side of the agitating roller 23, and communicates with the developing tank 21 through a toner replenishing port 30. Toner supply tank 2
A toner replenishing roller 31 and a pair of toner carrying screws 32 are rotatably mounted in the unit 9.

Below the toner replenishing port 30, a conveying screw 33 for conveying the developer from the front side to the rear side in the longitudinal direction of the developing tank 21 is rotatably arranged.

The front side of the carrying screw 33 is installed inside a carry-in cylinder 34 projecting from the developing tank 21.
A developer supply port 35 is formed in the developer supply port 35, and a developer supply tank 37 is connected to the developer supply port 35 via a pipe 36.

An agitator 38 is provided on the inner side of the carrying screw 33, and a U is provided around the carrying screw 33.
A letter-shaped transport path 39 is provided. The conveyance path 39 has an opening 39a directed upward, and the opening 39a is enlarged from the front side to the back side.

A recess 40 is formed at the bottom of the developing tank 21, and a discharge cylinder 41 is provided in a continuous manner with the recess 40 on the front side of the main body of the image forming apparatus.

The center of the rotary member 25 is a straight line extending from the center O of the developing roller 22 to the center point P1 where the magnetic force between the releasing pole S2 and the lifting pole S3 of the developing roller 22 becomes zero gauss. It is arranged on 42. Rotating body 25
Is a screw in which a spiral blade 44 is attached to the shaft 25a, and is installed in the recess 40 and the discharge tube 41.
Is rotatably supported on the developing tank wall and the end of the discharge cylinder via a bearing 43.

Then, the rotating body 25 and the developing roller 22.
A wall surface 45 of the developing tank 21 between and is formed parallel to the linear extension line 42 and is inclined toward the recess 40.

A developer discharge port 24 is formed in the lower portion of the discharge cylinder 41, and the discharge port 24 is connected to a recovery container 47 through a discharge pipe 46.

A shutter 4 for opening and closing is provided at the discharge port 24.
8 is provided and is controlled so that the discharge port 24 is closed at the time of development and opened when the developer is discharged.

The developing roller 22, the agitating roller 23, the conveying screw 33 and the rotating body 25 are geared by driving devices such as different motors arranged on the back side of the image forming apparatus main body which is the other side of the developing apparatus. It is rotationally driven via.

In FIG. 1, 49 is a toner density sensor.

In the above structure, at the time of development, the stirring roller 23, the conveying screw 33, and the rotating body 25 are rotated to stir the developer in the entire developing tank 21, and the developer is supplied to the developing roller 22. At this time, the shutter 48
Is closed and the outlet 24 is closed.

The developer supplied to the developing roller 22 is adsorbed by the lifting pole S3 of the developing roller 22, and on the sleeve surface, the lifting pole S3 to the transport pole N2, the transport pole N2 to the transport pole S1, and the transport pole S1. To development main pole N1, development main pole N
Move from 1 to release pole S2.

At this time, since the release pole S2 and the lifting pole S3 are the same pole, the magnetic force between the release pole S2 and the lifting pole S3 is applied to the developer not adsorbed on the photoconductor 26 due to the repulsive force. It is released from the surface of the sleeve in the vicinity of the portion P1 that becomes zero gauss. Then, it is agitated in the developing tank 21 by the agitating roller 23.

As the developer is used, the developer deteriorates and reaches the end of its life. Therefore, the developer must be replaced. Then, when the operation key is turned on, the developing roller 22, the stirring roller 23, and the conveying screw 33 rotate, and the rotating body 25 also rotates. Then, the shutter 48 is opened and the discharge port 24 is opened.

The developer, which has adhered to the developing roller 22 and has moved, has a releasing pole S2 and a lifting pole S3 of the developing roller 22.
In the vicinity of the midpoint P1 between and, it falls off from the developing roller 22 and hits the wall surface 45 of the developing tank 21, falls along the inclination of the wall surface 45 to the bottom of the developing tank, and gathers in the recess 40. Then, the developer is conveyed by the rotating body 25 toward the discharge port 24, drops from the discharge port 24 to the discharge pipe 46, and is collected in the collection container 47.

When the collection of the old developer is completed, the shutter 48 is closed and the discharge port 24 is closed. Next, new developer D is supplied. The developer is the developer supply tank 3
7 flows into the carry-in cylinder 34 and falls from the developer supply port 35 into the developing tank 21. The developer supplied to the developing tank 21 is diffused into the developing tank 21 by the conveying screw 33.

As described above, when the developer is replaced, the magnetic force on the surface of the developing roller 22 becomes a zero gauss midpoint P1.
The rotating body 25 is arranged on a straight extension line 42 connecting the center of the developing roller 22 and the center O of the developing roller 22, and a wall surface 45 of the developing tank 21.
Is inclined in parallel with the straight extension line 42, so that the developer released from the developing roller 22 smoothly drops onto the rotating body 25.

Since all the developer around the stirring roller 23 also concentrates on the rotating body 25, the developer in the developing tank 21 can be completely discharged.

Therefore, since the old developer does not remain in the developing tank 21, it does not mix with the newly introduced developer, and the copy image quality is not adversely affected.

Further, it becomes unnecessary for the service person to manually discharge the sheet during the discharging operation.

(Second Embodiment) FIG. 4 is a block diagram of a developing device showing a second embodiment of the present invention.

In the developing device of this embodiment, as shown in FIG. 4, the rotating body 25 has the releasing pole S2 and the lifting pole S3 of the developing roller 22.
Between a center point P1 of the developing roller 22 and the center O of the developing roller 22, and a perpendicular line 50 drawn from the center O of the developing roller 22. The other structure is the same as that of the first embodiment.

When the developer is replaced, the developing roller 22
The upper developer is released near the midpoint P1 where the magnetic force on the surface of the developing roller 22 becomes zero gauss, and falls downward due to gravity.

Since the rotating body 25 is disposed almost directly below the midpoint P1 of the developing roller 22, the developer drops onto the rotating body 25.

As described above, since all the developer released from the developing roller 22 concentrates on the rotating body 25, the developing tank 2
The developer in 1 can be completely discharged to the outside of the developing tank 21.

(Third Embodiment) FIG. 5 is a block diagram of a developing device showing a third embodiment of the present invention.

In the developing device of this embodiment, as shown in FIG. 5, the rotating body 25 has the releasing pole S2 and the lifting pole S3 of the developing roller 22.
Between the center point P1 of the developing roller 22 and the center O of the developing roller 22 and a perpendicular line 50 descending from the center O of the developing roller 22, and between the developing roller 22 and the stirring roller 23. It is arranged below the connecting tangent line 51. The other structure is the same as that of the first embodiment.

When the developer is replaced, the developing roller 22
The upper developer is released near the midpoint P1 where the magnetic force on the surface of the developing roller 22 becomes zero gauss, and falls downward due to gravity.

Since the rotating body 25 is disposed almost directly below the midpoint P1 of the developing roller 22, the developer drops onto the rotating body 25.

As described above, the developer released from the developing roller 22 is concentrated on the rotating body 25, so that the developer in the developing tank 21 can be exhausted to the outside of the developing tank 21 without being left over.

During the development, the developer collects in the recess 40, and the rotating body 25 is arranged below the outer tangent line 51 connecting the developing roller 22 and the agitating roller 23. The developer moves from the contact point M with the developing roller 22 toward the contact point N with the stirring roller 23, and is smoothly conveyed to the stirring roller 23 without being hindered by the outer shape of the rotating body 25.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, the position of the rotating body 25 in the first embodiment is not limited to the midpoint P1 between the release pole S2 and the lifting pole S3 of the developing roller 22, but may be within the range where the magnetic force is zero gauss. .

Although the respective embodiments have been described as above, in short, according to the present invention, the lifting pole S3 of the developing roller 22 for starting the conveyance of the developer and the developer after the development are conveyed to the stirring section. Since the releasing pole S2 to be returned has the same polarity, there is a portion where the magnetic force disappears, and the developer is at the position where the developing roller 22
More released. This release position includes magnetic poles S3 and S
2 within the range, that is, within the range surrounded by the extension line of the center of S3 and the extension line of the magnetic pole center of the magnetic pole S2 (within the range enclosed by the angle θ in FIG. 3). By providing the rotating body 25 for stirring and discharging and transporting the developer within this range, the developer released from the developing roller 22 is stirred, while the released developer can be efficiently transported and discharged during the discharge.

Further, in this case, as a particularly effective means, it is important that the position of the rotation shaft center of the rotating body 25 is lower than the shaft center O of the developing roller 22. In other words, the developer released from the developing roller 22 falls onto the rotating body 25, which ensures the recovery of the developer. To this end, the developing roller 22
In order for the range (angle θ) surrounded by the lifting pole S3 and the release pole S2 of FIG.
Each magnetic pole of the developing roller 22 needs to be set.

Therefore, according to the embodiment shown in FIG. 1, the point P at the portion where the magnetic force between the adjacent magnetic poles S2 and S3 disappears.
By providing the rotation center of the rotating body 25 so as to be located on the extension line 42 of No. 1, the above conditions are satisfied, and the recovery efficiency of the developer is increased.

Further, according to the embodiment shown in FIGS. 4 and 5, the range in which the rotating body 25 is provided is further narrowed to further enhance the developer collecting effect. Particularly, at the lifting pole S3, since the magnetic force gradually increases after passing the point P1, the developer that has been once released tends to be attracted to the developing roller 22 to be conveyed again. However, before that, it can be conveyed and discharged by the rotating body 25, and the collection can be performed more effectively. In particular, since the rotating body 25 is arranged below the point P1 where the magnetic force disappears, the developer released from the developing roller 22 can be collected. Moreover, the rotating body 25 is located inside the extension line of the release pole S2 (the perpendicular line 5 from the center O of the developing roller 22).
If it is provided within 0), the developer to be released is sequentially conveyed and discharged, which is more effective.

[0057]

As is apparent from the above description, according to the first aspect of the present invention, the rotating body for discharging and conveying the developer is surrounded by the releasing pole and the lifting pole which are the same pole of the developing roller. Since the developer released from the developing roller is agitated, the released developer can be efficiently conveyed and discharged at the time of discharging.

According to the second aspect of the present invention, the rotating body is arranged in the lower portion of the developing tank, and the magnetic poles of the developing roller are set so that the lifting pole and the releasing pole of the developing roller face downward. The developer released from the roller falls onto the rotating body, and the developer can be reliably collected.

According to the third aspect, since the range in which the rotating body is provided is further narrowed down, the developer to be released is sequentially conveyed and discharged, and the efficiency of collecting the developer is improved, which is more effective. become.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a developing device showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a developing device.

FIG. 3 is a diagram showing a magnetic force distribution on the surface of the developing roller.

FIG. 4 is a sectional view of a developing device showing a second embodiment.

FIG. 5 is a sectional view of a developing device showing a third embodiment.

FIG. 6 is a sectional view of a conventional developing device.

[Explanation of symbols]

21 developing tank 22 developing roller 23 stirring roller 24 discharge port 25 rotating body 42 straight line connecting the center of the developing roller and the midpoint between the release pole and the lifting pole 45 wall surface 50 vertical line from the center of the developing roller 51 developing roller and stirring roller Outer diameter tangent line connecting to S2 Release pole S3 Lifting pole

Claims (3)

[Claims] 1. A developing roller and a stirring roller are rotatably mounted in a developing tank, a developer discharge port is formed at the bottom of the developing tank, and a rotating body for discharging the developer from the discharge port to the outside of the developing tank is provided. In the provided developing device, the rotating body is
A developing device, wherein the developing device is arranged within a range surrounded by a release pole and a lifting pole, which are the same pole of the developing roller. 2. The rotating member is arranged at a lower portion of the developing tank, and each magnetic pole of the developing roller is set so that a space between the releasing pole and the lifting pole of the developing roller faces downward. 1. The developing device according to 1. 3. The rotating body is on an extension line of a straight line connecting a center point where the magnetic force between the releasing pole and the lifting pole of the developing roller is eliminated and the developing roller shaft center, or from the extending line and the developing roller shaft center. 2. The apparatus is arranged within a range surrounded by the lowered perpendicular, or within the range and below an outer diameter tangent line connecting the developing roller and the stirring roller.
Alternatively, the developing device according to claim 2.