JP2523639Y2 - Magnet roll - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnet roll, and more particularly, to a magnet roll having a simple structure and a double pole magnetic pole.

The magnet roll according to the present invention is used for a developing device and a cleaning device such as an electrophotographic copying machine, a printer, and a facsimile.

[Conventional technology and problems]

Conventionally, this type of magnet roll has a number of poles around a shaft (11) having a polygonal cross section as shown in FIG.
Adhesion of sintered magnets, metal magnets or magnets (12a) to (12d) molded by extraction or injection molding,
Although not shown, a sleeve, a flange, and the like are attached thereto, and are attached to a developing device magnet roll support portion of a copying machine or the like. However, in the method of bonding magnets as described above, if the number of poles is four or more, the bonding and management of the magnet to be used are complicated, quality defects such as magnetic force and angle are problematic, and there are many problems in productivity.

Recently, a method of integrally molding the shaft with the same material as the magnet and a method of extruding a cylindrical magnet and inserting the shaft have been proposed. However, in the method of integrally molding and the method of using a cylindrical magnet, when the number of poles is 5 or more, when a normal DC electromagnet is used,
Injection molds, extrusion dies, compression molds, and other dimensional restrictions make it impossible to increase the electromagnet capacity for orientation, and ensure a magnetic field strength of 5000 Gauss or more, preferably 5500 Gauss or more, necessary for the orientation yoke surface. This makes it difficult to obtain the degree of orientation required to provide a surface magnetic flux density of 900 gauss or more, which is necessary for a magnet roll.

Further, with a single-pole magnetic pole generally used, it is difficult to control the stirring of the toner and the movement of the toner to the electrostatic latent image, and it is difficult to obtain a good image. Therefore, conventionally, a method of securing two or more peaks of the magnetic flux density in one magnetic pole has been adopted.

That is, as shown in FIG. 5, the specific polarity magnet (13)
A method of providing a notch (14) on the surface of the magnet, or arranging two magnets (15a) and (15b) at appropriate distances as shown in FIG. However, these methods have problems such as a small difference between the peak and the valley (FIG. 7Y) and a shortage of the magnetic force of the peak itself (FIG. 7X), and sufficient results can be obtained. The fact is that it has not been reached.

In addition, repulsion occurs between the left and right magnet magnetic pole portions of the notch (14) in FIG. 4 (A) or between the two magnets (15a) and (15b) in FIG. 5 (A) because they have the same polarity. This is disadvantageous because a force may act to cause demagnetization or deformation due to repulsion.

The present invention has been made in view of the above circumstances, and has as its object to provide a magnet roll that has solved the above-mentioned problems.

[Means for solving the problem]

That is, the present invention provides a magnet roll comprising a shaft and a magnet having a plurality of magnetic poles disposed around the shaft, wherein at least one magnetic pole portion is provided with a concave portion from the outer peripheral surface, and the concave portion has a magnet having a polarity opposite to that of the magnetic pole. It has a magnet roll characterized in that a piece is embedded.

〔Example〕

The present invention will be described with reference to the drawings showing embodiments.
FIG. 1 shows a V-shaped depression (3) on the outer peripheral surface of a specific polarity magnet (2), which is separated from the shaft (1), of a plurality of polar magnets disposed around the shaft (1).
And a magnet piece (4) having a polarity (S) opposite to the specific polarity (N) is provided in the depression (3).
It is preferable that the magnet piece (4) is adhered by adhesion, adhesion, welding or the like. As an adhesive, vinyl acetate-vinyl chloride copolymer,
Examples include thermoplastic resin adhesives such as acrylic, polyvinyl ether, and cyanoacrylate adhesives, thermosetting resin adhesives such as epoxy and phenol, and rubber adhesives.

FIG. 2 shows another embodiment of the present invention, in which a specific polarity magnet (2) of a plurality of polarity magnets disposed around the shaft (1) is concavely formed on the outer peripheral surface of the magnet (2) separated from the shaft (1). And a depression (3) is provided.
Further, a magnet piece (4) having a polarity (S) opposite to the specific polarity (N) is provided.

FIG. 3 shows still another embodiment of the present invention, wherein a magnet (2) having a specific polarity is provided with a concave recess (3) penetrating from the outer peripheral surface to the shaft (1), and the concave recess (3) is provided in the concave recess (3). It has a configuration in which a magnet piece (4) having a polarity (S) opposite to the specific polarity (N) is embedded.

The magnetic flux density pattern of the magnet roll having the configuration shown in FIGS. 1 to 3 is schematically shown in FIG. 7. In any case, the difference between the peak and the valley and the magnetic force of the peak itself are both sufficient. Things are obtained.

As the magnet material used in the present invention, any of a sintered magnet and a plastic magnet can be used, but a plastic magnet is preferable in terms of moldability, light weight, adhesiveness and the like. As a material of the plastic magnet, a known resin or rubber is used, for example, ethylene-vinyl acetate copolymer, polyamide, polypropylene, polyethylene, vinyl chloride resin, acrylic resin,
Methacryl resin, chlorinated polyethylene resin, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polycarbonate, silicone rubber, NBR, SBR, etc. are used alone or in combination, and the magnetic powder used in the present invention is magneto Ferrites such as plumbite type Sr or Ba ferrite and Sm
-Co alloys, rare earths such as Ne-Fe-B, and Al-Ni-Co magnetic powders are suitable. The content of the magnetic powder is preferably 50 to 70% by volume. Known additives are used according to the purpose. That is, regarding the dispersibility of the magnetic powder, an appropriate surface treatment agent is used depending on the resin used. For example, a silane coupling agent, a titanate coupling agent, a zircoaluminate coupling agent, a higher fatty acid and a metal thereof Salts, phosphonates and the like are included in this. In addition, additives such as a stability improver, an antioxidant, an ultraviolet absorber, and a lubricant are appropriately used according to the purpose and in relation to the resin.

[Action / Effect]

According to the present invention, the magnetic poles can be made bimodal, and the magnetic flux density difference between the peak and the valley can be increased with a simple structure without significantly lowering the magnetic flux density at the peak, and the image quality can be improved. In order to increase the magnetic flux density difference between the peak and the valley, it is preferable that the concave dent penetrates from the outer peripheral surface to the shaft, but in this case, the magnets on the left and right of the concave dent need to be formed separately, so production The top is a little complicated. When the concave depression has a depth that is appropriately away from the shaft, it is useful in that the magnets on the left and right sides of the concave depression can be integrally formed and the productivity is high. According to the present invention, since a magnet having a polarity opposite to that of the magnetic pole is provided in the concave recess, an attractive force acts between the magnet magnetic poles, and there is a concern that demagnetization or deformation due to repulsive force occurs as in the conventional method. There is no.

As described above, according to the present invention, it is possible to form a bimodal magnetic pole having an appropriately large magnetic flux density difference between peaks and valleys without causing a significant decrease in surface magnetic flux density from a simple structure, and It is possible to obtain a magnet roll having no fear of demagnetization or deformation. Such a magnet roll is effective for obtaining a high-quality image.

[Brief description of the drawings]

1 to 3 are schematic diagrams each showing an embodiment of the magnet roll of the present invention, FIGS. 4 to 6 are schematic diagrams each showing a conventional magnet roll, and FIG.
FIG. 7 is a magnetic flux density pattern diagram of the magnet roll shown in FIGS. 3 to 3 and FIGS. 5 and 6. 1 ... Shaft 2 ... Specific polarity magnet 3 ... Recess 4 ... Magnet piece 11 ... Shaft 12a-12d ... Magnet 13 ... Specific polarity magnet 14 ... Notch 15a, 15b ... Magnet A ... No. Magnetic flux density pattern of the magnet roll shown in FIG. 1 B: magnetic flux density pattern of the magnet roll shown in FIG. 2 C: magnetic flux density pattern of the magnet roll shown in FIG. 3 X: shown in FIG. Magnetic flux density pattern of magnet roll Y: Magnetic flux density pattern of magnet roll shown in FIG.

Claims (3)

(57) [Scope of request for utility model registration] 1. A magnet roll comprising a shaft and a plurality of magnetic pole magnets disposed around the shaft.
A magnet roll, wherein at least one magnetic pole portion is provided with a concave portion from the outer peripheral surface, and a magnet piece having a polarity opposite to that of the magnetic pole is embedded in the concave portion. 2. The magnet roll according to claim 1, wherein the recess penetrates from the outer peripheral surface to the shaft. 3. The magnet roll according to claim 1, wherein the recess has a depth appropriately separated from the shaft.