JPH11161027A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the scattering of a developer from the end parts of developing rollers to the outside of a developing device, even if the device is mounted sideways with respect to a photoreceptive drum by providing magnetic members in the positions of both end parts in axial directions of the developing rollers, in the vicinity of a part where the first and second developing rollers face each other. SOLUTION: Magnetic members 13 are provided in the positions of both end parts in the axial directions of developing rollers 5 and 8 and in the vicinity of a part where the developing roller 5 and the developing roller 8 face each other. The magnetic members 13 are provided in the rear of developer regulating members 2 and the magnetic poles of the magnetic members 13 are provided in polarities (S-poles) opposite to those of magnetic poles (N-poles) located in the vicinities of the magnetic members 13 of the developing rollers 5 and 8. Thus, a developer in the end parts of the developing rollers 5 and 8 is stuck to the magnetic members 13 before the developer is discharged outside a developing device so that the scattering of the developer can be prevented. Further, the developer stuck to the magnetic members 13 forms a magnetic shield and the scattering of the developer to the outside from the end parts of the developing rollers 5 and 8 can be prevented by the magnetic shield.

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 for an image forming apparatus such as a laser printer and a copying machine.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIG. Two developing rollers 5 and 8 are provided opposite to the surface of the photoconductive drum 1 having photoconductivity. The developer 15 contained in the developing container 12 is brought into contact with the photosensitive drum 1 by the rotation of the conveying member 16. Developing roller 8 rotating in the opposite direction (counterclockwise)
And is held on the surface of the sleeve 7 by the attractive force of the fixed magnet 6 constituting the developing roller 8. The developer 15 held on the surface of the sleeve 7 is moved by the rotation of the sleeve 7 of the developing roller 8, the amount of the developer contributing to the development is regulated by the regulating member 2, and is conveyed to the developing area of the developing roller 8. On the other hand, the developer 15 regulated by the regulating member 2 and not conveyed to the developing area of the developing roller 8 is conveyed to the developing roller 5 rotating in the same direction (clockwise) as the photosensitive drum 1, and fixed to form the developing roller 5. Magnet 3
Is held on the surface of the sleeve 4 by the suction force. The developer 15 held on the surface of the sleeve 4 is moved by the rotation of the sleeve 4 of the developing roller 5, the amount of the developer contributing to the development is regulated by the regulating member 2, and is conveyed to the developing area of the developing roller 5.

The developer 15 that has passed the developing areas of the developing rollers 5 and 8 is returned to the developing container 12 again. In the drawing, 17 is a toner hopper, 18 is a toner feed roller, and 19 is a toner. When the toner in the developer 15 is consumed and falls below a certain toner concentration, the toner 19 is transferred from the toner hopper 17 to the developing container 12 side. Replenish.

[0004]

In the prior art, since the developing device is disposed below the photosensitive drum 1, even if the developer scattered from the developing device is generated, the developing device falls naturally. Could be received by the developing container, but if the installation position of the developing device is restricted as described above in consideration of the scattered developer, there is an obstacle in miniaturizing the image forming apparatus. It may be.

An object of the present invention is to provide a developing device capable of reliably preventing the developer from scattering from the end of the developing roller to the outside of the developing device even when the developing device is mounted horizontally on the photosensitive drum. Is to do.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a first developing roller rotatably supported on a shaft, and a first developing roller rotatably supported on a direction opposite to the first developing roller. In a developing device having a second developing roller disposed in an up-down relationship, a magnetic material is provided near a position where the first and second developing rollers face each other and at positions at both axial ends of the developing roller. This is achieved by having members.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The two developing rollers 5 and 8 are arranged in a vertical relationship so as to face the surface of the photosensitive drum 1 having photoconductivity, and the developer 15 contained in the developing container 12 is provided with a paddle roller 9. The developing roller 8 rotates in the opposite direction (counterclockwise) from the photosensitive drum 1 by the rotation of
And is held on the surface of the sleeve 7 by the attractive force of the fixed magnet 6 constituting the developing roller 8. The developer 15 held on the surface of the sleeve 7 is moved by the rotation of the sleeve 7 of the developing roller 8, the amount of the developer contributing to the development is regulated by the regulating member 2, and is conveyed to the developing area of the developing roller 8. On the other hand, the developer 15 regulated by the regulating member 2 and not conveyed to the developing area of the developing roller 8 is conveyed to the developing roller 5 rotating in the same direction (clockwise) as the photosensitive drum 1, and fixed to form the developing roller 5. Magnet 3
Is held on the surface of the sleeve 4 by the suction force. The developer 15 held on the surface of the sleeve 4 is moved by the rotation of the sleeve 4 of the developing roller 5, the amount of the developer contributing to the development is regulated by the regulating member 2, and is conveyed to the developing area of the developing roller 5.

The developer 15 that has passed through the developing area of the developing roller 8 is returned to the developing container 12 again. The developer 15 that has passed through the developing area of the developing roller 5 is
4 is scraped off from the developing roller 5 by the scraper 14.
It slides down the top surface and is returned to the developer reservoir of the developing container 12,
The developer is again supplied from the developer reservoir to the developing roller 5 by the auger screws 10 and 11 and the paddle roller 9.
In the figure, 17 is a toner hopper, 18 is a toner feed roller, and 19 is a toner. When the toner in the developer 15 is consumed and falls below a certain toner concentration, the toner 19 is transferred from the toner hopper 17 to the developing container 12 side. Replenish.

Here, in the developing device of the present invention, the magnetic member 13 is provided near the position where the developing roller 5 and the developing roller 8 are opposed to each other and at both axial ends of the developing roller (see FIG. 2). ing. In this embodiment, the magnetic member 13
Is provided behind the developer regulating member 2, and the magnetic pole of the magnetic member 13 is provided at a polarity (S pole) opposite to the magnetic pole (N pole) located near the magnetic member 13 of the developing rollers 5, 8.

With this configuration, the developer at the end of the developing roller adheres to the magnetic member 13 before the developer goes out of the developing device, thereby preventing the developer from scattering. Further, the developer attached to the magnetic member 13 forms a magnetic shield, and the newly transported developer can be prevented from being scattered outside from the end of the developing roller by the magnetic shield.

As means for preventing the developer from scattering from the developing device as in the present invention, for example, it is conceivable to provide a sealing member or an elastic member by pressing it against the developing roller.
In this case, since the seal member and the elastic member are in contact with the developing roller, when the contact portion is clogged with the developer, the developer clogged in the contact portion forms a developer layer on the outer peripheral surface of the developing roller. For this reason, the film cannot be expected to be used for a long period of time, such as causing a so-called filming phenomenon, and the effect being unable to be obtained early due to mutual wear. On the other hand, in the present invention, since the magnetic shield is formed as described above, the clogging of the developer and the abrasion between the developers do not occur, and the life of the developing device can be greatly extended. In addition,
In this embodiment, the magnetic force of the magnetic member 13 is 10
It was confirmed that particularly good effects were obtained in the range of 0 to 1500 Gauss.

[0012]

According to the present invention, even if the developing device is mounted horizontally on the photosensitive drum, the developing device can reliably prevent the developer from scattering from the end of the developing roller to the outside of the developing device. Can be provided.

[Brief description of the drawings]

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

FIG. 2 is a schematic side view taken in the direction of arrow A in FIG. 1;

FIG. 3 is a schematic front view showing a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2 ... Developer regulating member, 5, 8 ... Development roller, 9 ... Paddle roller, 10, 11 ... Auger screw, 12 ... Development container, 13 ... Magnetic member, 15 ... Developer
17: toner hopper, 18: toner feed roller, 1
9: toner.

(72) Inventor Koji Kato 1060 Takeda, Hitachinaka-city, Ibaraki Pref.Hitachi Koki Co., Ltd.

Claims (4)

[Claims] A first developing roller rotatably supported on the first developing roller;
A developing device having a second developing roller rotatably supported in a direction opposite to the first developing roller and arranged in a vertical relationship with the first developing roller; A developing device, comprising: a magnetic member near a position where the rollers face each other and at both axial ends of the developing roller. 2. The magnetic member has a magnetic force of 100 gauss or more and 1 or more.
2. The method according to claim 1, wherein the value is specified to be 500 gauss or less.
The developing device as described in the above. 3. The developing device according to claim 1, wherein a magnetic pole of said magnetic member is provided with a polarity opposite to a magnetic pole of said developing roller located near said magnetic member. 4. A developer regulating member which regulates the amount of developer supplied to each developing roller at a position where each of said developing rollers opposes each other, wherein said magnetic member is brought close to said developer regulating member. Claim 1 characterized by being provided
3. The developing device according to any one of 3.