JP3567722B2 - Magnet roller - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnet roller formed by bonding a plurality of magnet pieces.
[0002]
[Prior art]
As a magnet roller used in electrophotographic copiers, facsimile machines, laser printers, etc., a laminated magnet roller manufactured by laminating a plurality of magnetized magnet pieces with an adhesive or the like to form a predetermined magnetic field pattern. In addition, an integral type magnet roller manufactured by subjecting a cylindrical integral molded product made of a resin magnet material to a magnetizing treatment so as to have a predetermined magnetic field pattern has been widely put into practical use.
Although the lamination type magnet roller is more expensive to manufacture than the integrated type magnet roller, it can form a sharp magnetic field pattern and obtain a high magnetic flux density. It is used.
[0003]
In this type of magnet roller, one magnet piece is usually used in correspondence with one magnetic pole, and each magnet piece is provided with a magnetic field such that the direction of the magnetic particles is aligned in one predetermined direction according to the magnetic field pattern. Magnetized with medium orientation. When used in a developing device, a magnet roller is provided inside the sleeve so as to be relatively rotatable, and this is arranged in parallel with the photosensitive drum, and the developer is transferred from the sleeve to the photosensitive drum while rotating the sleeve. However, when the developer is delivered, a spike of beads of developer is formed from the sleeve toward the photosensitive drum according to the magnetic field pattern of the developing pole of the magnet roller. The developer is delivered by an electric attraction force by rubbing the surface of the developer or jumping the developer particles from the tip of the ear. The shape of the ear directly affects the development quality, but the best shape is set for each model based on the gap between the sleeve and the photosensitive drum, the rotational speed of the sleeve, and the like.
[0004]
[Problems to be solved by the invention]
By the way, in a conventional magnet roller using a ferrite-based magnetic powder, the magnetic flux density is increased by aligning the orientation and magnetization directions of the magnetic particles of the magnet pieces. Higher magnetic flux density is being demanded.
The present inventors have focused on the fact that the magnetic flux density is increased by converging the orientation and magnetization direction of the magnetic particles of the magnet pieces, and one magnetic pole is constituted by a plurality of magnet pieces, and the plurality of magnet pieces are formed. It has been found that a high magnetic flux density can be obtained by converging the orientation and magnetization directions of. Also, the shape of the magnetic field pattern is changed to a desired shape by changing at least one condition of the orientation magnetization angle of the magnet piece arranged so that the orientation magnetization direction is converged, the sectional shape of the magnet piece, and the amount of magnetization. It has been found that when set and applied to, for example, a developing pole, the shape of the ears of the developer can be adjusted.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a magnet roller which can increase the magnetic flux density at a desired magnetic pole with a simple configuration and can easily set a magnetic field pattern of the magnetic pole to a required shape.
[0006]
Means and action for solving the problem
The magnet roller according to claim 1, wherein at least one specific magnetic pole is configured by a plurality of magnet pieces, and at least one set of the magnetic pieces forming the specific magnetic pole is magnetically coupled to each other. The magnet pieces were arranged so as to repel each other, and the orientation magnetization angles of the pair of magnet pieces with respect to the mating surface were each set to 0 ° or more and 90 ° or less, and the sum of both orientation magnetization angles was set to be larger than 0 ° and less than 180 °. Things.
[0007]
In this magnet roller, at least one set of magnet pieces at a specific magnetic pole is disposed so as to magnetically repel each other, and the orientation magnetization angle of the set of magnet pieces with respect to the mating surface is 0 ° or more and 90 ° or less, respectively. In addition, the sum of the two orientation magnetization angles is set to be larger than 0 ° and less than 180 °, and the orientation magnetization directions of the set of magnet pieces are converged, so that the magnetic flux density at the specific magnetic pole is significantly increased. At the same time, the magnetic field pattern becomes sharp and the pole position is stabilized.
[0008]
As described in claim 2, the magnetic field pattern at a specific magnetic pole is changed to a magnetic pole peak by giving a difference to at least one condition of the orientation and magnetization angle of the set of magnet pieces, the cross-sectional shape of the magnet piece, and the amount of magnetization. It may be configured asymmetrically with respect to a line connecting the position and the center point of the magnet roller. With this configuration, the magnetic flux density at the specific magnetic pole is slightly lower than when one set of magnet pieces under the same conditions is used, but the magnetic field pattern at the specific magnetic pole can be easily set to a desired shape. For example, by forming the developing pole with this specific magnetic pole, it is possible to set the spike shape of the developer to an optimum shape.
[0009]
As described in claim 3, the magnetic field pattern at the specific magnetic pole is made asymmetric with respect to a line connecting the magnetic pole peak position and the center point of the magnet roller by giving a difference in the orientation magnetization angle of the one set of magnet pieces. It is preferable to configure. As a method of adjusting the shape of the magnetic field pattern, as described above, there is a method in which at least one condition of the orientation magnetization angle of one set of magnet pieces, the cross-sectional shape of the magnet pieces, and the amount of magnetization is varied. When the shape of the magnetic field pattern is adjusted by giving a difference in the orientation magnetization angle, it is possible to adopt a symmetric shape as one set of magnet pieces, and it is possible to perform fine angle adjustment, which is preferable.
[0010]
As described in claim 4, the conditions of the orientation and magnetization angle of the one set of magnet pieces, the cross-sectional shape of the magnet pieces, and the amount of magnetization are set to be the same, and the magnetic field pattern at the specific magnetic pole is set to the magnetic pole peak position. It may be configured to be mirror-symmetric with respect to a line connecting the center point of the magnet roller. This case is preferable because the magnetic flux density at the specific magnetic pole can be maximized, and the magnetic field pattern has a sharp shape.
[0011]
According to a fifth aspect of the present invention, a magnet piece for adjusting a magnetic field pattern may be provided as a magnet piece constituting the specific magnetic pole, in addition to the one set of magnet pieces. In this case, the magnetic field pattern at the specific magnetic pole can be easily set to a desired shape as in the case of the second and third aspects. For example, by forming the developing pole with this specific magnetic pole, the developer The standing shape can be set to an optimal shape.
[0012]
The specific magnetic pole may be constituted by a plurality of magnet pieces, and the plurality of magnetic poles other than the specific magnetic pole may be constituted by an integral magnet piece. Although it is possible to provide a magnet piece for each magnetic pole, manufacturing operations are complicated.For magnetic poles with low requirements for magnetic flux density, the magnetic properties of the magnet roller can be improved by configuring them with an integral magnet piece. , While reducing the manufacturing cost.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the shaft 2 is provided at the center of the magnet roller 1, the outer peripheral portion to form a four poles _{N 1,} S _1, N 2, _{S 2,} the magnetic poles _{N 1} Two magnet pieces 3 and 4 are provided at corresponding positions, and magnet pieces 5 to 7 are provided at positions corresponding to the magnetic poles S ₁ , N ₂ and S ₂ , respectively. The center is attached by an adhesive or the like. The magnet roller 1, a magnet roller for a developing device, relatively rotatably sleeve 8 is exterior to the magnet roller 1, the magnetic pole N ₁ is set to the developing pole.
[0014]
The shaft 2 may be made of various materials as long as it has strength and rigidity capable of supporting the magnet roller 1 without substantially bending. For example, a hard synthetic resin material, iron, stainless steel, or the like may be used. It is composed of a shaft made of a metal material or the like. Further, the shaft 2 can be formed of a hollow or solid square shaft or a round shaft, but is preferably formed of a square shaft to facilitate positioning of the magnet pieces 3 to 7. Further, in order to position the magnet pieces 3 to 7 with respect to the shaft 2, an uneven fitting portion or the like may be provided between the shaft 2 and the magnet pieces 3 to 7.
[0015]
The magnet pieces 3 to 7 are made of a known magnet such as a resin magnet or a sintered magnet, and are oriented and magnetized so that the magnetic field pattern of the magnet roller 1 has a shape as shown in FIG. The directions are set as indicated by arrows in FIG. These five magnet pieces 3 to 7 may be made of the same material or different materials.
[0016]
The magnet pieces 3 and 4 are formed in a mirror-symmetrical shape around the mating surface 9 and are magnetized so as to magnetically repel each other. The magnetic angles θa and θb are set so that the spike shape of the developer is optimal. That is, the spike shape of the developer corresponds to the shape of the magnetic field pattern, and the magnetic field pattern corresponds to half the maximum value of the magnetic flux density when the orientation magnetization angles θa and θb are set to θa> θb. When the central angles αa and αb of the magnetic field pattern are set to αa <αb, and the orientation magnetization angle is set to θa <θb, the central angle of the magnetic field pattern becomes αa> αb and the shape of the magnetic field pattern changes. By adjusting θa and θb, it is possible to change the shape of the magnetic field pattern and set the spike shape of the developer to an optimal shape.
[0017]
Orientation and磁角degree .theta.a magnet pieces 3 and 4, .theta.b is focuses the orientation and magnetization directions of the magnetic particles of magnet pieces 3 and 4, to increase the magnetic flux density at the pole N _1, orientation and磁角degree .theta.a, .theta.b Are each 0 ° or more and 90 ° or less, preferably 20 ° or more and 50 ° or less, and the sum of the orientation magnetization angles θa and θb is more than 0 ° and less than 180 °, preferably 1 ° or more and 120 ° or less, more preferably Is set to 2 ° or more and 100 ° or less. In particular, when the sum of the orientation magnetization angles θa and θb is set to 80 °, the magnetic flux density becomes the highest, and therefore it is preferable that the configuration satisfy this condition.
In addition, the magnetic flux density is highest when the angle of the orientation magnetization angles θa and θb is 0 °, but when the magnetic field pattern is adjusted with the angular difference, the magnetic flux density is not significantly reduced. It is preferable to set the angle to 80 ° or less.
[0018]
For example, as the magnet roller 21 shown in FIG. 3, when the maximum value of the magnetic flux density forming the pole _{N 1} with magnet pieces 23 and 24 of 800G, the orientation and磁角degree θa = θb = 40 ° If set, the maximum value of the magnetic flux density becomes 1000 G, than the case of forming the magnetic pole N ₁ with a single magnet pieces, the maximum value of the magnetic flux density is also increased 200G. However, in this magnet roller 21, the center angle of the magnetic field pattern corresponding to the half value (500 G) of the maximum value of the magnetic flux density is αa = αb, and the ears are set in the radial direction of the magnet roller 1.
When adjusting the shape of the ears, the orientation magnetization angles θa and θb have an angle difference. For example, as shown in FIG. 2, when the orientation magnetization angle is set to θa = 40 ° and θb = 10 °, the maximum value of the magnetic flux density is 970G, which is slightly lower than that of the magnet roller 21; The central angles αa and αb of the magnetic field pattern corresponding to the half value of the maximum value (485 G) are αa = 17 ° and αb = 22 °, the shape of the developer ears is adjusted, and the image quality of the developing device is improved. become.
[0019]
As a method of changing the shape of the ears, in addition to adjusting the orientation magnetization angles θa and θb as described above, a magnet piece having a different magnetization amount may be used, or one or both of the magnet pieces 3 and 4 may be used. A notch such as a concave groove is provided on the outer peripheral surface, or the difference in the amount of magnetization between the two magnet pieces 3A, 4A is determined by using magnet pieces 3A, 4A having different cross-sectional shapes like the magnet roller 1A shown in FIG. or to have, 5, of the magnet roller 1B, 1C shown in FIG. 6, separately or provided magnet pieces 10, 11 for changing the magnetic field pattern, or by combining these techniques, the pole N ₁ The spike shape may be changed by adjusting the magnetic field pattern.
[0020]
In the present embodiment, the magnetic poles S ₁ , N ₂ , and S ₂ are respectively constituted by the magnet pieces 5 to 7. However, in order to reduce the number of parts constituting the magnet roller and to reduce the manufacturing cost, the two magnetic poles are used. Can be constituted by one magnet piece, or three magnetic poles can be constituted by one magnet piece 12 like a magnet roller 1D shown in FIG. Also, the magnetic poles S ₁ , N ₂ , and S ₂ may be constituted by a plurality of magnet pieces as in the case of the magnetic pole N ₁ .
Further, in the present embodiment, the present invention is applied to the magnet roller 1 having four magnetic poles, but the present invention can be similarly applied to a magnet roller having a plurality of magnetic poles other than four.
[0021]
【The invention's effect】
According to the magnet roller according to the first aspect, at least one set of magnet pieces at the specific magnetic pole is arranged so as to magnetically repel each other, and the orientation magnetization angle of each set of magnet pieces with respect to the mating surface is 0. And the sum of the two orientation magnetization angles is set to be greater than 0 ° and less than 180 °, and the orientation magnetization directions of the set of magnet pieces are converged, so that the magnetic flux density at the specific magnetic pole And the pole position is stabilized, and the image quality can be significantly improved.
According to the magnet roller according to the second and third aspects, it is possible to easily set the magnetic field pattern at the specific magnetic pole to a desired shape. It is possible to further improve the image quality by setting the spike shape to the optimum shape.
[0022]
According to the magnet roller according to the fourth aspect, the magnetic field pattern at the specific magnetic pole is mirror-symmetrical with respect to a line connecting the magnetic pole peak position and the center point of the magnet roller. However, a high magnetic flux density can be obtained and the magnetic field pattern has a sharp shape.
According to the magnet roller of the fifth aspect, similarly to the second and third aspects, it is possible to easily set the magnetic field pattern at the specific magnetic pole to a desired shape. Thus, it is possible to set the spike shape of the developer to an optimum shape.
[0023]
According to the magnet roller of the sixth aspect, the specific magnetic pole is composed of a plurality of magnet pieces, and the plural magnetic poles other than the specific magnetic pole are composed of an integral magnet piece. And the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view of a magnet roller. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1. FIG. 3 is a cross-sectional view of a magnet roller in which the orientation and magnetization directions are mirror-symmetrical. FIG. FIG. 5 is a sectional view of a magnet roller of another embodiment. FIG. 6 is a sectional view of a magnet roller of another embodiment. FIG. 7 is a sectional view of a magnet roller of another embodiment. Description】
Reference Signs List 1 magnet roller 2 shaft 3 magnet piece 4 magnet piece 5 magnet piece 6 magnet piece 7 magnet piece 8 sleeve 9 mating surface 1A magnet roller 3A magnet piece 4A magnet piece 1B magnet roller 10 magnet piece 1C magnet roller 11 magnet piece 1D magnet roller 12 Magnet piece 21 Magnet roller 23 Magnet piece 24 Magnet piece

Claims (6)

A magnet roller in which at least one specific magnetic pole is constituted by a plurality of magnet pieces,
At least one set of the magnet pieces constituting the specific magnetic pole is disposed so as to magnetically repel each other, and the orientation magnetization angle of the one set of magnet pieces with respect to the mating surface is 0 ° or more and 90 ° or less. And the sum of both orientation magnetization angles is set to be greater than 0 ° and less than 180 °. At least one condition of the orientation magnetization angle of the one set of magnet pieces, the cross-sectional shape of the magnet piece, and the amount of magnetization is set differently, and the magnetic field pattern at the specific magnetic pole is changed to the magnetic pole peak position and the center point of the magnet roller. 2. The magnet roller according to claim 1, wherein the magnet roller is configured to be asymmetrical with respect to a line connecting. 3. The magnetic field pattern at a specific magnetic pole is configured to be asymmetrical with respect to a line connecting a magnetic pole peak position and a center point of a magnet roller by giving a difference in the orientation magnetization angle of the one set of magnet pieces. Magnet roller. The same condition is set for the orientation magnetization angle of the one set of magnet pieces, the cross-sectional shape of the magnet pieces, and the amount of magnetization, and the magnetic field pattern at the specific magnetic pole is connected between the magnetic pole peak position and the center point of the magnet roller. 2. The magnet roller according to claim 1, wherein the magnet roller is configured to be mirror symmetric with respect to the line. 2. The magnet roller according to claim 1, wherein a magnet piece for adjusting a magnetic field pattern is provided as a magnet piece constituting the specific magnetic pole, in addition to the one set of magnet pieces. The magnet roller according to any one of claims 1 to 5, wherein the specific magnetic pole includes a plurality of magnet pieces, and a plurality of magnetic poles other than the specific magnetic pole includes an integral magnet piece.

Images