JPH04478A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic image forming apparatus using a magnet.

[Conventional technology]

Conventionally, this type of image forming apparatus visualizes an electrostatic latent image formed on the surface of an image bearing member such as a photoreceptor by attaching a developer to it. The image carrier is carried in small amounts near the surface of the image carrier by the developer carrier. The developer is generally a -component magnetic toner or a two-component consisting of a magnetic carrier and a non-magnetic toner. In order to attach these magnetic developers to the developer carrier, a magnet is placed inside the developer carrier. It is set up.

On the other hand, one of the configurations of an image forming apparatus is a removable process cartridge type. This means that at least an image bearing member such as a photoreceptor, generally an image bearing member, a charging processing means for the image bearing member, a developing processing means, and a cleaning means for the image bearing member are connected to a common cartridge. The cover (cartridge frame, housing) is assembled in a predetermined positional relationship with each other, and these are assembled together so that even an amateur can easily attach and detach them to and from the main body of the image forming apparatus. .

In principle, this removable process cartridge is used to form a specified number of images (for example, 3,000 to 5,000 sheets) and then is replaced with a new process cartridge, assuming that its useful life has come to an end. The maintenance of the device is free, improving the operability and handling of the image forming device, and by using several process cartridges containing different colors of developer, it is possible to form multicolor images. Because of these advantages, it has been put to practical use as one configuration of an image forming apparatus, such as a personal type, compact and simple model.

[Problem to be solved by the invention]

However, if there is a magnet inside the process cartridge mentioned above, the magnetic field will also leak to the outside of the process cartridge, so if magnetic recording media or precision electronic equipment are placed nearby, it may cause noise or cause unstable operation. There was a problem. Also, when shipping by air, if you pack in large quantities, IAT
This solved the problem of inefficiency as it was not possible to pack in large quantities because it was classified as dangerous goods by the International Air Transport Association.

The present invention aims to solve the above problems. That is, an object of the present invention is to provide an image forming apparatus in which the magnetic field of a magnet provided inside a process cartridge is prevented from leaking to the outside.

[Means to solve the problem]

To achieve the above object, the present invention provides an image forming apparatus in which a developing means for visualizing a latent image on the surface of an image carrier has a fixed magnet, in which at least the developing means is detachably attached to a main body. The present invention is configured as a part of a process cartridge, and a magnetic plate is disposed in a direction near the maximum magnetic flux density on the surface of the process cartridge created by the magnet in the process cartridge.

[Function] According to the present invention, since the magnetic plate is disposed at least in the portion facing the maximum magnetic flux density of the outer cover of the process cartridge, leakage of the magnetic field caused by the magnet to the outside can be prevented.

〔Example〕

FIG. 1 is a schematic cross-sectional view of a process cartridge according to a first embodiment of the present invention.

In the figure, reference numeral 1 denotes a photoreceptor, which is approximately cylindrical and has a photosensitive layer formed on the surface of a conductive base material.

2 is a developing device into which magnetic toner (not shown) is placed. A cleaner 3 collects unnecessary residual toner on the photoreceptor 1 and stores it. Reference numeral 4 denotes an outer cover that integrally holds the photoreceptor 1, the developing device 2, and the cleaner 3. 5 is a magnetic plate that covers the entire back surface of the developer 2 and the cleaner 3.
It is glued to the entire back surface. Reference numeral 6 denotes a developer carrier, which is made of a non-magnetic conductor and has a substantially cylindrical shape that can rotate like the photoreceptor 1, and a substantially cylindrical fixed magnet 7 is disposed inside so as not to come into contact with the developer carrier 6. has been done. 8 is a non-magnetic developer application blade that uniformly coats the toner on the developer carrier 6. Also, the arrow A of the fixed magnet 7 in FIG.
B indicates the maximum direction when the magnetic flux density of the magnet 7 is measured in the circumferential direction, arrow A is facing the photoreceptor 1 and is about 700 gauss at the south pole, and arrow B is about 600 gauss at the north pole. .

In addition, the outer cover 4, the container for the developer 2, and the container for the cleaner 3 are also made of non-magnetic plastic (for example, polycarbonate).
It consists of

This process cartridge blocks light and dirt,
It is sealed in an opaque bag (not shown) and packed in a paper packaging box 10 with a cushioning material 11 such as Styrofoam used to soften the impact. The maximum magnetic flux density on the outer surface of this packaging box 10 was approximately 1 Gauss. This is approximately 10 cm 1 l from the center of the magnet 7 at the back of the developing device 2.
I'm bored. Also, when the magnetic plate 5 was taken and measured, it was about 4 Gauss at the same measurement location.

In this way, the magnetic plate 5 is aligned in the maximum magnetic flux density direction of the fixed magnet 7.
By simply placing the , the external magnetic field created by the process cartridge can be reduced.

In Fig. 1, the magnetic plate 5 is placed in the back of both the developer 2 and the cleaner 3, but if the maximum magnetic flux density were in another direction,
The magnetic plate 5 may be installed in that direction, and the magnetic plate 5 on the back surface of the developing device 2 or the back surface of the cleaner 3 may be eliminated.

Furthermore, although the magnetic plate 5 is installed between the back of the developer 2 and cleaner 3 and the outer cover 4, it is not integrated with the cover or the container either outside the outer cover 4 or inside the developer 2 or cleaner 3. In short, it is sufficient to provide the magnetic flux density in the direction where the magnetic flux density is maximum.

Note that if the cleaner 3 is provided with a magnet such as a magnet roll or if a plurality of magnets are left in the cartridge, the magnetic plate 5 may be arranged in the direction of the maximum magnetic field formed by all the magnets.

FIG. 2 shows a second embodiment of the invention.

This second embodiment is a case where the process cartridge is composed of only the developing device 2. The fixed magnet 7 has four poles, and the direction of maximum magnetic flux density is indicated by an arrow. Developer carrier 6
The toner coating member 12 that coats the upper toner is a magnetic material that does not contact the developer carrier 6. Reference numeral 14 denotes a deflection prevention member that prevents the magnet 7 from being drawn to the toner coating member 12 and deflected. A magnetic plate 5 for preventing leakage of the magnetic field to the outside of the cartridge is provided on the back surface of the developing device 2 and on the back surface of the cover 13 that protects the surface of the developer carrier 6.

Figure 's3 shows the state in which the developer carrier 6 in Figure 2 is exposed. That is, when installing the cartridge in the main body, the protective cover 13 is automatically or manually opened and the developer carrier 6 is exposed. expose.

〔Effect of the invention〕

As explained above, according to the present invention, when there is one or more fixed magnets in the process cartridge, the magnetic plate is provided in the direction in which the magnetic field produced by all the magnets becomes maximum. Leakage of the magnetic field to the outside of the cartridge can be made extremely small, which has the effect of suppressing adverse effects on other electronic devices and magnetic media.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the first embodiment of the present invention, Fig. 2 is a sectional view also showing the second embodiment, and Fig. 3 is a sectional view of Fig. 2 with the protective cover opened. be. 1...Photoreceptor 2...Developer 3...Cleaner 4...Outer cover 5...Magnetic plate
6...Developer carrier 7...Fixed magnet 13
...Protective cover Figure 1 Figure 2 Figure 3 and 4 others

Claims (1)

[Claims] 1. In an image forming apparatus in which a developing means for visualizing a latent image on the surface of an image carrier has a fixed magnet, at least the developing means is configured as a part of a process cartridge that is detachably attached to the main body. , and a magnetic plate is disposed in a direction near a maximum of magnetic flux density on the surface of the process cartridge created by a magnet in the process cartridge.