JPS645301B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnet roller in an electrostatic transfer type electrophotographic copying machine.

It is known to use a magnetic brush in a developing method or a cleaning method in an electrostatic transfer type electrophotographic copying machine.

A magnet roller is usually used as a means for forming this magnetic brush. This magnetic roller generally has a plurality of magnets arranged in the hollow part of a cylindrical sleeve made of non-magnetic material such as aluminum or resin, so that adjacent magnets have different polarities. One or both of the magnets are rotated such that there is relative movement therebetween to retain the developer on the sleeve surface.

In the case of magnet rotation or both rotation, it is desirable that the magnetic field on the sleeve surface be formed approximately equally over the entire circumference of the sleeve (even around the entire circumference of the sleeve in the cleaning device).

By the way, in a conventional magnet roller, the magnet body is constructed by magnetizing a single ferromagnetic material so that adjacent polarities are opposite to each other.

For this reason, the weight of the magnet increases, and a magnet roll that rotates the magnet has the disadvantage that the rotational load increases. In addition, in particular, magnet rollers that rotate magnets are required to have more dense magnetic lines of force, which inevitably leads to an increase in the number of magnetized poles, resulting in poor orientation. It had the disadvantage of becoming a magnet.

In view of the above-mentioned points, an object of the present invention is to provide a magnet roller that eliminates the above-mentioned drawbacks.

The present invention will be explained below with reference to an illustrated embodiment.

FIG. 1 is a perspective view showing the structure of a magnet roller according to the present invention.

This magnet roller 1 includes a cylindrical sleeve 2 made of a non-magnetic material such as aluminum or non-magnetic stainless steel, and a plurality of fins 3a formed radially from the center of the sleeve 2 along the axial direction of the sleeve 2. The yoke 3 is made of a ferromagnetic material, and a plurality of magnets 4 (four in the illustrated embodiment) are arranged between the fins 3a of the yoke 3. magnet 4
are arranged so that the direction of magnetization is radial to the center of the sleeve 2.

The yoke 3 and each magnet 4 may be integrated with each other using an adhesive (see Fig. 2), or as shown in Fig. 3, the yoke 3 and each magnet 4 may be combined and then assembled. They may be inserted into a heat-shrinkable tube 5, and the tube 5 may be heated and shrunk to be integrated with each other.

The magnet body 6 (see FIG. 2), which is constructed by integrating the yoke 3 and each magnet 4, is inserted into the sleeve 2 as shown in FIG. The extending end surface of each fin 3a and the circumferential surface of each magnet 4 are formed in a size that does not contact the inner circumferential surface of the sleeve 2.

Furthermore, as shown in FIG. 4, each magnet 4
are arranged so that the north pole faces the sleeve side, the south pole of each magnet 4 comes into contact with the yoke 3. Therefore, an S pole is generated at the end of each fin 3a located between each of these magnets 4, and a magnetic field is generated between each of these fins 3a and the different pole (N pole) of the adjacent magnet 4. It is formed.

The magnet roller configured as described above is
Since each magnet forming the magnet body is arranged individually, standardized off-the-shelf magnets can be used. Since it is constructed by combining these materials, it is lighter than a magnet made of a single material, has good magnetic field orientation, and has an inexpensive and highly reliable structure. Therefore, since the weight can be reduced, the rotational torque can be reduced, and the orientation can be improved, so that a large magnetic field can be obtained on the sleeve surface. Furthermore, when constructed from a single material, the number of poles is limited to 8 to 10 due to processing, but with this method, it is possible to achieve a higher number of poles.

The above-described magnet roller can be used for both development and cleaning by appropriately changing the polarity of the magnet and the positions of the magnets and fins.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a perspective view of only the magnet body in the above embodiment,
FIG. 3 is a side view showing another example of the structure of the magnet body;
FIG. 4 is a side view of the above embodiment. 1...Magnetic roller, 2...Sleeve, 3
... Yoke, 3a ... Fin, 4 ... Magnet, 5 ...
Heat-shrinkable tube, 6... Magnet.

Claims (1)

[Claims] 1 A cylindrical sleeve made of a non-magnetic material, and a yoke made of a magnetic material that is loosely inserted into the hollow part of this sleeve and has a plurality of fins radially formed from the center of the sleeve along the axial direction of this sleeve. and a plurality of magnets arranged between each fin of the yoke and having a size that does not contact the inner circumferential surface of the sleeve, and the magnetization direction of the plurality of magnets is relative to the center of the sleeve. 1. A magnet roller, wherein the magnetic rollers are arranged so as to face in a radial direction, and the magnetic poles of each magnet on the side facing the inner circumferential surface of the sleeve have the same polarity.