JPH1138766A - Magnetizing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase magnetization efficiency and obtain large magnetic force by magnetizing a magnetization object so that the interval between the magnetic poles to be magnetized of the magnetization object adjoining the rotating direction of the magnetization object satisfies a specific relational expression. SOLUTION: A roll-like magnetization object 2 is rotated, and the magnetization object 2 is magnetized to S, N in its rotating direction by magnetic heads 17 each wound with an exciting coil on a core having two magnetic pole ends facing each other at the prescribed interval in the rotating direction of the magnetization object 2 in this magnetizing method. The magnetic poles to be magnetized of the magnetization object 2 are magnetized at the interval D between them satisfying 1.0 mm >=D>=2d, where (d) is the size of the gap section 17a of the magnetic head 17. When the magnetization object Z is magnetized at the interval D sufficiently larger than the size (d) of the gap section 17 a, the overlappingly magnetized portion is reduced, and magnetization efficiency is increased. The gradient of the magnetization magnetic flux density can be increased, and the magnetic force is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetizing method for magnetizing S and N alternately in the rotation direction of a body to be magnetized using a magnetizing head.

[0002]

2. Description of the Related Art Generally, in an electrophotographic image forming apparatus, a latent image is formed on an image carrier due to a difference in charged potential.
Further, a visible image is formed by attaching a toner to the latent image with a developing device incorporated in the image forming apparatus.
Such a developing device for visualizing a latent image has a developer carrier that carries a developer on a peripheral surface and is driven to rotate, and the developer carrier contacts or is close to the image carrier. The toner is transferred in an electric field formed between the developer carrier and the image carrier. As the developer carrier, a carrier that transports the developer by magnetically adsorbing a magnetic carrier in a magnetic toner or a two-component developer is generally used. The magnetic pole is magnetized. Here, a magnetizing method using a magnetizing head to magnetize the developer carrying member has been conventionally known. This magnetizing method is such that a magnetizing head is brought into contact with or close to the peripheral surface of a magnetized body which is a drum-shaped magnetic body or a magnetized layer having a magnetic layer near the peripheral surface, and the magnetized body is rotated. This is a method in which a magnetized head is magnetized by a magnetizing head while moving in the same direction as the direction of the magnetic force lines of the magnetizing head. According to this method, the gap between the magnetic poles can be reduced by reducing the size of the gap of the magnetizing head that generates the magnetic field. However, on the other hand, the magnetic flux density generated from the magnetized head is small,
The magnetic flux density of the magnetized magnetic pole becomes small, and the magnetization is performed while moving the magnetized body in the same direction as the direction of the magnetic force of the magnetized head.
Therefore, there is a problem that it is difficult to obtain strong magnetization.

Accordingly, Japanese Patent Laid-Open No. 4-75077 discloses that
There has been proposed a technique for obtaining a strong magnetization by using a magnetic material having a coercive force of 200 [Oe] or more for a developer carrier. In addition, γ-Fe ₂ O ₃ , Ba
-Fe, Ni-Co and the like. Japanese Patent Application Laid-Open No. Hei 6-26881 proposes a technique of magnetizing with a magnetizing current having a pulse width of 20% to 30% of an interval between magnetized magnetic poles. Generally, when the magnetizing current is small, the magnetizing magnetic flux density is small, and when the magnetizing current is large, the magnetizing magnetic flux density is large. However, when the magnetizing current exceeds a predetermined value, the magnetized magnetic poles interfere with each other, and the apparent magnetic flux density decreases. For this reason, Japanese Unexamined Patent Application Publication No.
In the technique disclosed in JP-A-81, magnetizing is performed under the magnetizing condition of a trade-off between an increase in the magnetic flux density of the magnetic pole alone due to an increase in the magnetizing current and a decrease in the magnetic flux density due to interference between the magnetic poles.

[0004]

However, it is considered that the cause of the decrease in the magnetic flux density is not only the interference between the magnetic poles after magnetization but also the magnetization. FIG. 10 is a diagram for explaining a conventional magnetizing method for magnetizing an object to be magnetized by a magnetizing head.

The lines of magnetic force generated by the magnetization head 1 are shown in FIG.
As shown in FIG. 2, the magnetized magnetic head 2 exists on the magnetized body 2 over a wider range than the size of the gap 1a of the magnetized head 1.
Are magnetized according to such lines of magnetic force. Here, focusing on the magnetized region of the magnetized body 2, the magnetized body 2
The directions of magnetization of the region inside the gap 1a and the regions at both ends outside the gap 1a are different from each other as shown by arrows in FIG.

FIG. 11 is a view showing a state in which a magnetizing head is moved in the rotating direction of a magnetized body and magnetizing is performed by applying a continuous magnetizing current. The magnetized object 2 is a magnetized head 1
Is magnetized over a wider range than the size of the gap 1a, the magnetic field lines in the region inside the gap 1a and the magnetic lines of force in the region outside the gap 1a overlap each other in the magnetic body 2, so Offset by direction. Therefore, when the magnetizing head 1 is moved in the rotation direction of the magnetized body 2 and a continuous magnetizing current is applied to magnetize the magnetized body 2, the magnetized body 2 is magnetized while receiving magnetization in the opposite direction. The magnetization efficiency is poor, and the magnetization density distribution is distorted, so that a sharp magnetization waveform cannot be obtained and it is difficult to obtain a large magnetic force.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a magnetizing method capable of increasing the magnetizing efficiency and obtaining a large magnetic force.

[0008]

According to the present invention, there is provided a magnetizing method for rotating a roll-shaped magnetic body while rotating the roll-like magnetic body at a predetermined interval d in the rotation direction of the magnetic body. A magnetizing head having an exciting coil wound around a core having two magnetic poles, wherein the magnetizing method alternately magnetizes S and N in the rotation direction of the magnetized body. When the distance between the magnetic poles of the magnetized body adjacent to the magnetic pole to be magnetized is D, the magnetization is performed at an interval D satisfying 1.0 mm ≧ D ≧ 2d.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the magnetizing method of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a magnetizing apparatus to which a magnetizing method according to one embodiment of the present invention is applied. The magnetizing device 10 is used for magnetizing a plurality of magnetic poles on the peripheral surface of a cylindrical magnetized body 2. A support member 15 that supports the magnetized body 2 rotatably around its axis. And a rotation driving unit 14 for applying a rotation driving force to the support member 15, and a magnetizing head 17 is disposed at a position facing the peripheral surface of the magnetized body 2. It is supported on a head support member 16 that is moved in the axial direction of the magnetic body 2 by a drive shaft 18. The magnetizing head 17 includes a magnetizing power supply device 20.
Supplies a magnetizing current.

The magnetic body 2 is made of a cylindrical ferrite, a rubber roll containing a magnetic material, Ni, Co, Te—Fe, Gd.
A magnetic material such as Co.
It is driven to rotate around the X 'axis at a predetermined rotation speed. Also,
The movement of the head support member 16 is performed by rotating the drive shaft 18 around the axis. FIG. 2 is a diagram showing the magnetized body and the magnetized head shown in FIG.

As shown in FIG. 2, the magnetizing head 17 has a C-shaped core 17b made of a soft magnetic material. An exciting coil 17c is wound around the center of the core 17b. 17c, a magnetizing current is supplied from the magnetizing power supply device 20 shown in FIG. As a result, a magnetic field is generated in the gap 17a of the magnetization head 17, and the magnetic field
Is magnetized.

Next, the operation of the magnetizing device 10 shown in FIG. 1 will be described. The magnetized body 2 having an endless peripheral surface is mounted on the support member 15 of the magnetizing device 10 and the drive shaft 18 is rotated to a position on the peripheral surface of the magnetized body 2 where magnetization is started. The magnetizing head 17 is moved. Next, the cylindrical magnetized body 2
Is rotated at a predetermined number of revolutions by the rotation drive unit 14, and at the same time, the magnetization head 17 is moved at a predetermined speed in the axial direction. Further, a magnetizing current is supplied from the magnetizing power supply device 20 to the exciting coil 17c. Then, the gap 1 of the magnetized head 17
A magnetic field is generated at 7a. The magnetic body 2 is magnetized by this magnetic field, and a magnetic pole pattern is formed in the direction of rotation of the magnetic body 2 and the direction of movement of the magnetizing head 17.

FIG. 3 is a view showing a magnetic pole pattern of a magnetic body formed by the magnetizing apparatus shown in FIG. S and N are alternately provided in the rotation direction A of the magnetized body 2.
Are formed, and S and N magnetic pole patterns are formed in a line in the moving direction B of the magnetizing head 17.

Next, the magnetizing method will be described. FIG.
FIG. 4 is a diagram illustrating a state in which a magnetized head magnetizes in a rotation direction of a magnetized body. In the magnetizing method according to the present embodiment, the distance between magnetic poles adjacent to the magnetized body 2 in the rotation direction and magnetized of the magnetized body 2 is D, and the size of the gap 17a of the magnetized head 17 is When d is set, the magnetization is performed at an interval D satisfying 1.0 mm ≧ D ≧ 2d. in this way,
When the magnetization is performed at an interval D sufficiently larger than the dimension d of the gap portion 17a, the overlap magnetized portion is reduced, and the magnetization efficiency is increased. Further, since the gradient of the magnetization magnetic flux density can be made large, the magnetic force also becomes large.

When the magnetization is performed while the magnetized body 2 is continuously rotated, a similar phenomenon occurs in a minute area in one pulse-like current waveform. That is, while the pulsed current is being applied, the magnetized body 2 is rotating, so that there is a portion that receives magnetization in the opposite direction during one pulse. In order to prevent this, it is necessary to use a magnetizing head 17 in which the dimension d of the gap 17a is large. However, the gap 17
If the dimension d of a is too large, the resolution becomes worse,
The number of lines of magnetic force spreading outside the gap 17a also increases.

FIG. 5 is a graph showing the relationship between the magnetizing current application interval, ie, the magnetizing current application distance determined by the magnetizing time and the magnetizing speed, and the magnetizing magnetic flux density. FIG. 6 is a diagram showing a typical pulsed magnetizing current waveform. The graph shown in FIG. 5 shows three types of magnetizing current application distances and magnetizing magnetic flux densities when magnetizing at a magnetic pole interval D = 100 μm using the magnetizing head 17 having the gap d of dimension 90 = 90 μm. Is shown. FIG. 6 shows three discrete pulse-like magnetizing current waveforms representing these three magnetizing current application distances. Specifically, FIG.
FIG. 6B shows a magnetizing current at a current application distance of 10 μm, FIG. 6B shows a magnetizing current at a current application distance of 30 μm, and FIG. 6C shows a magnetizing current at a current application distance of 50 μm. I have. Incidentally, when a continuous magnetizing current is applied, the current application distance is 100 μm, which is the same as the magnetic pole interval.
As is clear from FIG. 5, the shorter the current application distance, the higher the magnetized magnetic flux density. Further, the size of the region to be magnetized also changes depending on the magnitude of the magnetizing current. In the part where the magnetizing current is small, the magnetized area is small because the magnetized area is small, and the magnetic flux density increases as the magnetizing current increases, but when the magnetizing current exceeds 0.4 A _pp , the magnetized area is Are overlapped with each other, and as described above, the magnetization directions are offset by different directions of magnetization, and the magnetic flux density is reduced.

FIG. 7 is a graph showing the relationship between the size of the gap in the magnetizing head and the magnetizing magnetic flux density. FIG. 7 shows the relationship between the size of the gap of the magnetizing head and the magnetizing magnetic flux density when magnetizing at the magnetic pole interval D = 100 μm.
The magnetizing current application distance was set to 10% of the dimension d of the gap 17a. From FIG. 7, the magnetic pole interval D = 100 μ
It can be seen that a sufficient magnetic force can be obtained by magnetizing with a magnetizing head having a size of the air gap 17a of about half or more of m.

FIG. 8 is a diagram showing a magnetized waveform when magnetized by a magnetized head having the size of the gap shown in FIG.
FIG. 8A shows a magnetization waveform when magnetized by a magnetization head having a gap dimension d = 45 μm, and FIG.
Magnetized waveforms when magnetized by a magnetized head having a gap dimension d = 90 μm are shown. FIG. 8 (a)
It can be seen that the magnetization waveform shown in FIG. 8 has a larger magnetic flux density gradient than the magnetization waveform shown in FIG. That is, the magnetic force can be increased. This is presumably because the magnetizing head having a smaller gap 17a can be magnetized with higher resolution.

FIG. 9 shows the conventional magnetizing magnetic flux density when a continuous magnetizing current is applied and the magnetizing magnetic flux density according to the present embodiment when a discrete pulse-like magnetizing current is applied. It is a figure which showed and compared the magnitude | size. From FIG. 9, it can be seen that when the optimum current value (0.4 A _PP ) is selected, a magnetic flux density almost 1.5 times as high can be obtained.

In this embodiment, the magnetized body 2 has
A higher magnetic flux density may be obtained by using a magnetic material such as γ-Fe ₂ O ₃ , Ba—Fe, or Ni—Co.

[0021]

As described above, according to the present invention,
Since the direction of magnetization applied to each point on the magnetic material during magnetization can be made as constant as possible, the magnetization efficiency can be increased and a large magnetic flux density can be obtained. Therefore, it is possible to manufacture a mag roll which can obtain a strong magnetic force with a low distortion and a sharp magnetization waveform.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a magnetizing device to which a magnetizing method according to an embodiment of the present invention is applied.

FIG. 2 is a view showing a magnetized body and a magnetized head shown in FIG. 1;

FIG. 3 is a view showing a magnetic pole pattern of a body to be magnetized, formed by the magnetizing apparatus shown in FIG. 1;

FIG. 4 is a diagram illustrating a state in which a magnetized head is magnetized in a rotation direction of a body to be magnetized.

FIG. 5 is a graph showing a relationship between a magnetizing current application interval, ie, a magnetizing current application distance determined by a magnetizing time and a magnetizing speed, and a magnetizing magnetic flux density.

FIG. 6 is a diagram showing discrete pulse-like magnetizing current waveforms.

FIG. 7 is a graph showing the relationship between the size of the air gap of the magnetizing head and the magnetizing magnetic flux density.

8 is a diagram showing a magnetization waveform when magnetized by a magnetization head having the size of the gap shown in FIG. 7;

FIG. 9 shows the magnitude of the conventional magnetizing magnetic flux density when a continuous magnetizing current is applied and the magnetic flux density of the present embodiment when a discrete pulse-like magnetizing current is applied. FIG.

FIG. 10 is a diagram for explaining a conventional magnetizing method for magnetizing a magnetic body with a magnetizing head.

FIG. 11 is a view showing a state in which a magnetizing head is moved in a rotation direction of a magnetized body and a continuous magnetizing current is applied to perform magnetizing.

[Explanation of symbols]

 2 Magnetized object 10 Magnetization device 14 Rotation drive unit 15 Support member 16 Head support member 17 Magnetization head 17a Air gap 17b Core 17c Excitation coil 18 Drive shaft 20 Magnetization power supply device

Claims (2)

[Claims] 1. A method in which a roll-shaped magnetic body is opposed to a rotating magnetic body while rotating the magnetic body at a predetermined distance d in the rotation direction of the magnetic body.
Using a magnetizing head in which an exciting coil is wound around a core having two magnetic poles, S and S are alternately arranged in the rotation direction of the magnetic body.
In the magnetizing method for magnetizing N, when an interval between magnetic poles adjacent to the magnetized body in the rotation direction and magnetized on the magnetized body is D, 1.0 mm ≧ D ≧ 2d is satisfied. A magnetizing method characterized by magnetizing at intervals D. 2. The magnetized object is magnetized by supplying a discrete-pulse magnetizing current in which the direction of the current is alternately changed to an exciting coil of the magnetizing head. 2. The magnetizing method according to 1.