JPH05289496A - Developing device - Google Patents

Abstract

PURPOSE:To supply a developer without having irregularities in stirring in an axial direction, to a developing roller by providing an auxiliary stirring roller stirring the developer in the circumferential direction, in the vicinity of a shielding member preventing the irregularities in the carrying of the developer. CONSTITUTION:The auxiliary stirring roller 10 is composed of a metallic roller shaft 10a freely rotatably supported by a developing tank 1, and resin blades 10b having uniform cross-sections in the axial direction, and provided projectingly in opposite directions to each other. The auxiliary stirring roller 10 is disposed so as to be located in the vicinity of the surface of the developer in the developing tank 1, on the upstream side of the shielding member 6. The developer is stirred in the circumferential direction, while being stirred in the axial direction of the stirring roller 3, as well. The developer collid with the shielding member 6 and is sent to the auxiliary stirring roller 10 while the irregularities in the stirring is reduced. Since the developer is uniformly pressed in the radial direction of the auxiliary stirring roller 10, by the blade 10b projectingly provided on the stirring roller 10, so that the irregularities in the stirring in the axial direction is completely eliminated, and the developer is supplied to the developing roller 2.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A conventional developing device for an image forming apparatus is shown in FIG.
, The developing roller 2 and the agitating roller 3,
An agitator 4 is rotatably installed. Then, the developing roller 2 is rotated counterclockwise, and the stirring roller 3 and the agitator 4 are rotated clockwise.

The agitating roller 3 has an outer diameter of about 36 mm and, as shown in FIG. 7, a metallic roller shaft 3a rotatably supported by the developing tank 1 and a resin externally fitted and fixed to the roller shaft 3a. The blade 5 is made of. The blade 5 is an elliptical fin 5a
And a vertical fin 5b protruding from the roller shaft 3a in the radial direction between the elliptical fins 5a.

In order to efficiently stir the developer, the stirring roller 3 has a structure capable of stirring in the axial direction with the elliptical fins 5a and also in the circumferential direction with the vertical fins 5b.

The developer supplied to the developing roller 2 by the agitating roller 3 has coarse pitches of the elliptical fins 5a, so that the agitation unevenness in the axial direction occurs due to periodical pressure and bulk changes. When halftone copying is performed, unevenness in the axial direction appears as unevenness in the image and the copy quality.

In order to prevent the uneven stirring in the axial direction, a shielding member 6 is arranged between the developing roller 2 and the stirring roller 3,
The developer with uneven stirring is collided with the shielding member 6 before being supplied to the developing roller 2 so that the pressure difference of the developer due to the rotation of the stirring roller 3 is not directly transmitted to the developing roller 2. In this way, the uneven stirring is reduced so that the developing roller 2 is not directly affected by the stirring of the stirring roller 3.

In FIG. 6, 1a is an opening, 1b is a toner replenishing port, 7 is a photoconductor, 8 is a doctor for controlling the spike of the developer on the developing roller 2, and 9 is a toner concentration sensor.

[0008]

However, even if the conventional shielding member 6 is arranged, the uneven stirring can be slightly reduced, but it is not completely improved. Still, the uneven image appears in the copy image quality in the halftone copy. It was

In view of the above, it is an object of the present invention to provide a developing device for supplying a developing roller with a developer having no axial uneven stirring.

[0010]

As shown in FIGS. 1 and 2, a means for solving the problems according to the present invention includes a developing tank 1, a developing roller 2, and
In the developing device, the agitating roller 3 is rotatably incorporated, and a shielding member 6 is provided between the developing roller 2 and the agitating roller 3 to prevent uneven conveyance of the developer.
An auxiliary stirring roller 10 that stirs the developer supplied from the stirring roller 3 over the shielding member 6 to the developing roller 2 in the circumferential direction is provided in the vicinity of.

[0011]

In the above means for solving the problems, the developer is agitated by the agitating roller 3 in the axial direction while being agitated in the circumferential direction, and the agitation unevenness occurs periodically due to the change in pressure and bulk.

The developer is sent to the auxiliary stirring roller 10 while colliding with the shielding member 6 and uneven stirring is reduced.
Here, since the developer is pushed by the auxiliary stirring roller 10, the stirring unevenness is completely erased, and the developer stable in the axial direction is supplied to the developing roller 2 to develop the electrostatic latent image.

[0013]

1 is a sectional view of a developing device showing an embodiment of the present invention, FIG. 2 is a perspective view of an auxiliary stirring roller, FIG. 3 is a plan view of a developing tank showing a driving mechanism of each roller, and FIG. FIG. 5 is a side view of the drive mechanism seen from the back side of the copying machine body, and FIG. 5 is a side view of the drive mechanism seen from the front side of the copying machine body. It should be noted that the same reference numerals are given to the same components as the conventional one.

The developing device of the copying machine according to the present embodiment includes a developing tank 1.
Further, a developing roller 2 and an agitating roller 3 are rotatably provided inside, and a shielding member 6 for preventing unevenness in the conveyance of the developer is provided between the developing roller 2 and the agitating roller 3, and the shielding member 6 is provided.
An auxiliary stirring roller 10 that stirs the developer supplied from the stirring roller 3 over the shielding member 6 to the developing roller 2 in the circumferential direction is provided in the vicinity of.

In the developing tank 1, an opening 1a is formed on the side facing the photoconductor 7, the developing roller 2 is arranged on the side of the opening 1a, and the side more distant from the photoconductor 7 than the developing roller 2. Further, the stirring roller 3 and the agitator 4 are arranged on the side further separated from the stirring roller 3.

A toner replenishing port 1b is formed above the agitator 4 of the developing tank 1, and the toner replenishing port 1b is formed.
A toner replenishing tank (not shown) is detachably attached above the above.

The shielding member 6 is a flat plate-shaped developing roller 2.
Is located on a line connecting the centers of the stirring roller 3 and the stirring roller 3, and is fixedly installed in the developing tank 1 so that the distance between the stirring roller 3 and the stirring roller 3 is 0.3 mm to 0.8 mm.

The auxiliary stirring roller 10 has an outer diameter of about 15 m.
At about m, it has the same shape as the agitator 4,
As shown in FIG. 2, it is composed of a metal roller shaft 10a rotatably supported in the developing tank 1, and resin blades 10b having a uniform cross section in the axial direction and projecting in opposite directions. The blade 10b is externally fitted and fixed to the roller shaft 10a.

Further, the auxiliary stirring roller 10 includes the shielding member 6
Is arranged so as to be located near the surface of the developer in the developing tank 1 above. The stirring roller 3 is the same as the conventional one.

The drive mechanism for the developing roller 2, the stirring roller 3, the agitator 4 and the auxiliary stirring roller 10 will be described below. As shown in FIGS. Driving gears 11, 12, and 13 are attached to the ends of the shafts 2a, 3a, and 4a of the developing roller 2, the agitating roller 3, and the agitator 4 which penetrate the gears 11, 12 and 13, respectively. 12 mesh with each other, and the gear 12 of the stirring roller 3 and the gear 13 of the agitator 4 are meshed with each other.
Are meshed with each other via the idle gear 14.

On the front side of the main body of the copying machine in the developing tank 1,
As shown in FIGS. 3 and 5, the driven gear 15 of the stirring roller 3 and the driving gear of the auxiliary stirring roller 10 are attached to the ends of the shafts 3a, 10a of the stirring roller 3 and the auxiliary stirring roller 10 which penetrate the developing tank 1. 16 is attached, and the driven gear 15 of the stirring roller 3 is connected to the auxiliary stirring roller 10 via the idle gear 17.
Is meshed with the driving gear 16 of.

Then, the driving force of a main motor (not shown) of the copying machine main body is transmitted to the driving gear 11 of the developing roller 2 to rotate the driving gears 12 and 13, and further the driven gear of the stirring roller 3 is driven. When the gear 15 rotates, the drive gear 16 of the auxiliary stirring roller 10 rotates.
In the figure, 14a is the shaft of the idle gear 14, and 17a is the shaft of the idle gear 17.

In the above structure, the toner concentration sensor 9
The toner replenished through the toner replenishing port 1b in response to the command of # 1 drops onto the agitator 4. Then, by the rotation of the agitator 4, the developer and the toner in the developing tank 1 are rapidly mixed and stirred, and the developer is rubbed against each other and charged, and is sent to the stirring roller 3.

Thereafter, the developer is stirred by the stirring roller 3 in the circumferential direction while being stirred in the axial direction. At this time, due to the shape of the blades 5 of the agitating roller 3, the developer is periodically agitated in the axial direction due to variations in pressure and bulk.

The developer is sent to the auxiliary stirring roller 10 while colliding with the shielding member 6 to reduce uneven stirring. Here, since the developer is pushed by the blades 10b that are evenly projected in the radial direction of the auxiliary stirring roller 10, the stirring unevenness in the axial direction is completely erased, and the developer is supplied to the developing roller 2 and is transferred onto the photoconductor 7. To develop the electrostatic latent image.

As described above, the axial stirring unevenness of the developer caused by the stirring of the stirring roller 3 can be completely erased by the rotation of the shielding member 6 and the blade 10b of the auxiliary stirring roller 10, and therefore the developing roller. The developer can be uniformly supplied to No. 2. Therefore, it is possible to prevent image unevenness of copy quality caused by uneven stirring of the stirring roller 3 during halftone copying.

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

For example, the auxiliary stirring roller 10 and the shielding member 6
May be placed below or both above and below. Further, a flow plate may be arranged above the auxiliary stirring roller 10 to send the toner scraped off from the developing roller 2 to the stirring roller 3 side.

[0029]

As is clear from the above description, according to the present invention, the stirring unevenness of the developer caused by the stirring of the stirring roller can be completely erased by the shielding member and the auxiliary stirring roller. The developer can be evenly supplied. Therefore, there is an excellent effect that it is possible to prevent image unevenness of copy quality at the time of halftone copying.

[Brief description of drawings]

FIG. 1 is a sectional view of a developing device showing an embodiment of the present invention.

FIG. 2 is a perspective view of an auxiliary stirring roller.

FIG. 3 is a plan view of a developing tank showing a drive mechanism of each roller.

FIG. 4 is a side view of the drive mechanism seen from the back side of the copying machine main body.

FIG. 5 is a side view of the drive mechanism seen from the front of the copying machine main body.

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

FIG. 7 is a perspective view of a stirring roller.

[Explanation of symbols]

 1 developing tank 2 developing roller 3 stirring roller 6 shielding member 10 auxiliary stirring roller

Claims (1)

[Claims] 1. A developing device in which a developing roller and an agitating roller are rotatably incorporated in a developing tank, and a shielding member is provided between the developing roller and the agitating roller to prevent uneven transport of the developer. A developing device, characterized in that an auxiliary stirring roller for stirring the developer supplied from the stirring roller over the shielding member to the developing roller in the circumferential direction is provided in the vicinity of the shielding member.