JP3074114B2 - Developing device and process cartridge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for an image forming apparatus for forming an image on a recording medium and a process cartridge detachably attachable to a main body of the image forming apparatus and containing image forming means in a single housing.

[0002]

2. Description of the Related Art Image forming apparatuses such as printers and copiers are
The uniformly charged image carrier is selectively exposed to form a latent image, the latent image is visualized with toner attached to the developer carrier, and the toner image is transferred to a recording medium. To perform image recording. In such an apparatus, the toner must be replenished each time the toner runs out. However, this replenishment operation is not only troublesome, but also involves contamination. Further, maintenance of each member can only be performed by a specialized service technician, which often causes inconvenience to the user.

Therefore, an image carrier, charging means, developing means,
The cleaning means and the like are integrated into a cartridge to form a cartridge, so that the user can load the cartridge into the apparatus main body, thereby replenishing toner and replacing parts of the image carrier that has reached the end of its life, thereby facilitating maintenance. Has been put to practical use.

In such a developing device as a developing means of a process cartridge, at both ends of a rotating developer carrier (developing sleeve), a developer (toner) is prevented from flowing out of a developing area. Is provided. Conventionally, as a seal member for preventing the developer from flowing out, an elastic seal member such as felt or foamed rubber is widely used. Representative examples are shown in FIGS. FIG. 5 is a main cross-sectional configuration diagram of a developing device in a conventional process cartridge, and FIG. 6 is a cross-sectional configuration diagram of a developing device unit in a thrust direction.

The developing sleeve 4a has a magnet 4b therein, and is rotatably fixed to the toner container 3 via a sleeve bearing 5. The toner supplied from the toner container 3 adheres to the surface of the developing sleeve 4a by the magnetic pole, and after the layer thickness is regulated to be constant by the developing blade 4c, the toner adheres to the latent image on the image carrier (photosensitive drum) 1. You. At both ends of the developing sleeve 4a, elastic seal members 4d are fixed to the toner container 3 on the side facing the photosensitive drum 1, and are pressed against the outer peripheral surface of the developing sleeve 4a to prevent the toner from flowing out.

However, in such a structure, the elastic seal member 4 is pressed against the outer peripheral surface of the developing sleeve 4a.
There is a problem that the load due to d is large, and the elastic seal member 4d is deteriorated due to the contact with the developing sleeve 4a, and the sealing property is deteriorated. Further, a small amount of toner may enter between the developing sleeve 4a and the elastic seal member 4d, and the entered toner may cause aggregation and fusion to affect the image such as white stripes. Was.

[0007]

In order to solve these problems, there has been proposed a method of arranging a magnetic sealing member at both ends of a developing sleeve with a predetermined gap therebetween, thereby preventing toner from flowing out. I have. FIG. 4 is a sectional view of a main part of a developing device using a magnetic sealing member in a thrust direction.

The magnetic material sealing member 4d 'is
The toner container 3 is fixed to the toner container 3 on the side facing the photosensitive drum 1 at both ends of the photosensitive drum 1 with a fixed gap g from both ends thereof.
The developing sleeve 4a contains a magnet 4b, forms a concentrated magnetic field between the magnetic seal member 4d 'and the magnetic pole of the magnet 4b, and forms a magnetic brush by interposing toner in the gap g to develop the toner. It is prevented from flowing out of the area.

By using this technical means, since the developing sleeve and the magnetic seal member are not in contact with each other, the rotational torque of the developing sleeve is extremely small, and therefore the drive motor may be small and inexpensive. Also, since there is no abrasion or the like, its use is semi-permanent and can be recycled.

However, the sealing ability of the developer in the magnetic sealing member has not been sufficiently satisfactory. In particular, when user operability of the process cartridge is taken into consideration, for example, when an impact is applied when the process cartridge is mounted on the image forming apparatus main body, there is a great concern about the sealability of the developer.

Accordingly, an object of the present invention is to provide sufficient sealing performance even when an impact or the like is applied in consideration of user operability, and furthermore, the load on the developer carrying member is small and it can withstand long-term use. An object of the present invention is to provide a developing device and a process cartridge provided with the obtained seal member.

[0012]

The above object is achieved by a developing device and a process cartridge according to the present invention. According to the first aspect of the present invention, a rotatable developer carrier that carries and transports a developer, and is provided inside the developer carrier,
A magnet that gives a magnetic force to hold the developer on the developer carrier, and faces along the peripheral surface of the end of the developer carrier to prevent leakage of the developer from the end of the developer carrier A magnet seal member, and a magnetic brush of a developer is formed by a magnetic field between the magnet and the magnet seal member, wherein the magnet has a plurality of magnetic poles on a surface facing the magnet seal member. The magnet seal member includes a plurality of magnetic poles respectively opposed to the plurality of magnetic poles of the magnet, and for each of the plurality of magnetic poles of the magnet, the opposite magnetic pole of the magnet seal member is a reverse magnetic pole. A developing device is provided. According to one embodiment of the present invention, the magnet seal member includes a magnetic pole on a surface facing the developer carrier in addition to a magnetic pole facing the magnetic pole of the magnet.

According to a second aspect of the present invention, the developing device includes:
There is provided a process cartridge which has an image carrier on which the developing device performs a developing operation, and is detachable from an image forming apparatus main body.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a developing device and a process cartridge according to the present invention.

Referring to FIGS. 1 and 2, an embodiment of a process cartridge having a developing device according to the present invention will be described. 2 and 3 schematically show a process cartridge that can be attached to and detached from the image forming apparatus main body according to the present invention. FIG. 1 is a cross-sectional view of a process cartridge, and FIG. 2 is a cross-sectional view of a main part of the developing device.

This process cartridge has an image carrier and at least one process means. Here, examples of the processing means include a charging means for charging the surface of the image carrier, a developing means for forming a toner image on the image carrier, and a cleaning means for removing toner remaining on the surface of the image carrier.

The process cartridge of this embodiment is shown in FIG.
As shown in FIG. 1, a charging unit 2, a developing device 4 as a developing unit containing toner (developer), and a cleaning unit 6 are arranged around an electrophotographic photosensitive drum 1 as an image carrier. And is integrally formed as a cartridge by covering the housing made of the same, and is configured to be detachable from the image forming apparatus main body.

In the developing device 4, a magnet seal member 4e is fixed to the toner container 3 on the side opposite to the photosensitive drum 1 with a fixed gap g between both ends of the developing sleeve 4a and the outer peripheral surface thereof. Forming a concentrated magnetic field between the sealing member 4e and the magnetic pole of the magnet 4b included in the developing sleeve 4a;
The toner is prevented from flowing out of the developing area by forming the magnetic brush with the toner interposed in the gap g.

According to this embodiment, on the inner peripheral surface of the magnet seal member 4e, that is, the surface facing the outer peripheral surface of the developing sleeve 4a, the portion facing the magnetic pole magnetized by the magnet 4b is provided.
The opposite magnetic pole and the opposite magnetic pole are magnetized. As a result, the magnetic field formed in the gap g between the developing sleeve 4a and the magnet seal member 4e becomes very strong because they are attracted to each other due to the opposite magnetic poles, so that the binding force of the toner interposed in the gap increases.
Therefore, the sealing ability is improved as compared with the case where only the magnetic sealing member is used.

Next, another embodiment of the process cartridge provided with the developing device according to the present invention will be described with reference to FIG.

In the above embodiment, the magnet seal member 4
The example in which the opposing magnetic pole and the opposite magnetic pole are magnetized on the inner peripheral surface of e, that is, the surface of the surface facing the developing sleeve 4a that faces the magnetic pole magnetized by the magnet 4b, The magnetization of the inner peripheral surface of the magnet seal member 4e may be magnetized in other places as long as the opposite magnetic pole is magnetized in a portion facing the magnetic pole of the magnet 4b.

For example, as shown in FIG.
The S pole and the N pole may be magnetized at equal intervals on the inner peripheral surface of the magnet seal member 4e facing between the N, 2 poles and between the N2, S1 poles. As a result, the magnetic field formed between the sleeve and the magnet sealing member becomes denser, and thus the sealing performance is improved.

[0023]

As is apparent from the above description, the developing device and the process cartridge according to the present invention are provided inside a rotatable developer carrier for carrying and transporting the developer, and are provided inside the developer carrier. A magnet that provides a magnetic force for holding the developer on the developer carrier, and a magnet seal member that faces along the peripheral surface of the end of the developer carrier to prevent leakage of the developer from the end of the developer carrier Having a configuration in which a magnetic brush of the developer is formed by a magnetic field between the magnet and the magnet seal member, and further, the magnet includes a plurality of magnetic poles on a surface facing the magnet seal member, and the magnet seal member has A plurality of magnetic poles are respectively opposed to the plurality of magnetic poles of the magnet, and for each of the plurality of magnetic poles of the magnet, the magnetic poles of the magnet seal member facing each other are reverse magnetic poles, so that the sealing ability is improved, More effective It is possible to prevent the outflow to the outside of the developer. Therefore, even when an impact or the like is applied in consideration of user operability, the sealing performance can be sufficiently exerted, the load on the developer carrier is small, and it can withstand long-term use, and the life can be extended. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating an embodiment of a process cartridge provided with a developing device according to the present invention.

FIG. 2 is a cross-sectional configuration diagram illustrating a main part of a developing device of the process cartridge of FIG. 1;

FIG. 3 is a cross-sectional configuration diagram of a main part of a developing device of another embodiment of a process cartridge provided with the developing device according to the present invention.

FIG. 4 is a sectional view in a thrust direction showing a main part of a developing device of a conventional process cartridge using a magnetic sealing member.

FIG. 5 is a main cross-sectional configuration diagram of a developing device of a conventional process cartridge using an elastic seal member.

FIG. 6 is a cross-sectional view in a thrust direction of a main part of the developing device of the process cartridge of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 4 Developing means (developing device) 4a Developing sleeve (developer carrier) 4b Magnet included in developer carrier 4e Magnet seal member 6 Cleaning means g Gap between developer carrier and magnet seal member

Claims (3)

(57) [Claims] A rotatable developer carrying member for carrying and transporting a developer; a magnet provided inside the developer carrying member for providing a magnetic force for carrying the developer on the developer carrying member; A magnet seal member facing along the peripheral surface of the end of the developer carrier to prevent leakage of the developer from the end of the developer carrier, wherein the magnet and the magnet seal member In a developing device that forms a magnetic brush of a developer by a magnetic field between the magnet and the magnet, the magnet includes a plurality of magnetic poles on a surface facing the magnet seal member, and the magnet seal member faces the plurality of magnetic poles of the magnet, respectively. A developing device comprising: a plurality of magnetic poles, wherein a magnetic pole of the magnet seal member facing each of the plurality of magnetic poles of the magnet is a reverse magnetic pole. 2. The developing device according to claim 1, wherein the magnet seal member has a magnetic pole on a surface facing the developer carrier in addition to a magnetic pole facing the magnetic pole of the magnet. 3. A process cartridge comprising: the developing device according to claim 1; and an image carrier on which the developing device performs a developing operation, wherein the process cartridge is detachable from an image forming apparatus main body.