JPS5827911B2 - Magnetic bubble memory device magnetization/demagnetization device and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for magnetizing and demagnetizing a magnetic bubble memory device and a method for manufacturing the same, and more particularly to a device for magnetizing and demagnetizing a magnet block that applies a uniform bias magnetic field to a magnetic bubble memory chip and a method for manufacturing the same. It is.

Figures 1a and 1b are a top view and a cross-sectional view of a typical part of a magnetic bubble memory device, particularly a typical example of a magnet block that applies a uniform bias magnetic field onto an insulating substrate on which a magnetic bubble memory chip is mounted. be.

In these figures, 1 is a shield case made of a metal plate such as permalloy, and this shield case 1
has the function of shielding the magnetic field generated in the gap A and the external magnetic field.

Magnet plates 2 are closely arranged on the inner upper and lower surfaces of the shield case 1 to generate and apply a required magnetic field to the gap A.

Further, on the opposing surface of the magnet plate 2, a magnetic shunt plate 3 is arranged in close contact with the magnet plate 3, which enhances the uniformity of the magnetic field of the magnet plate 2 generated in the gap A.

In such a magnet block based on usurpation, the static magnetic field of the magnet plate 2 is essential for storing information, and the use of permanent magnets eliminates the need for energy for storing information, which is the advantage of the magnetic bubble memory device. It has become a feature.

Therefore, in a magnetic bubble memory device, the value of the static magnetic field must be set extremely precisely.

In general, the width of the external static magnetic field in which magnetic bubbles can exist and operate (this is usually called the bias magnetic field margin) is usually 100 to 110 oersteds, that is, about 10 oersteds as a margin, and saturation magnetization This is an extremely small value compared to the fact that the magnetic flux density on the surface of a magnet is several thousand Oersteds.

Therefore, in a magnet block for a magnetic bubble memory device, the value of the internal static magnetic field must be set extremely accurately.

Conventionally, magnetization and demagnetization of a magnet block as shown in Fig.
This was done using the method shown below.

That is, (1) a magnet block is installed between the pole pieces of an electromagnet that provides a uniform static magnetic field, and a constant current is passed through the electromagnet,
Saturation magnetization.

(2) Reverse the current direction to (1) and apply a constant current Io to demagnetize.

(3) Remove the magnet block from the electromagnet and measure the bias magnetic field with a Gaussmeter.

If this value is larger than the desired value, step (1) is performed again, and the value of Io in step (2) is slightly increased.

Further, when the bias magnetic field is small, the value of Io in the step (2) above is slightly decreased.

Magnet blocks formed by such a process have problems such as large variations in the bias magnetic field when the demagnetizing field is kept constant.
The bias magnetic field of the demagnetized magnet block varied from 50 to 130 oersted when the magnet block was set to 00±10 oersted.

Therefore, since steps (1) and (2) have to be repeated, there is a drawback that it takes a long time to magnetize and demagnetize one magnet block.

Moreover, the cause of this variation was the variation in the characteristics of the permanent magnet, which was essential.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an apparatus for magnetizing and demagnetizing a magnetic bubble memory device, which eliminates the above-mentioned drawbacks, can magnetize and demagnetize in a short time, and has high magnetization accuracy, and a method for manufacturing the same.

In order to achieve such objects, the present invention provides a magnetic bubble memory device magnetization/demagnetization device and a manufacturing method thereof.
A magnet block with a demagnetizing element interposed between the pole pieces of the electromagnet is arranged, and the output value of this magnetic sensing element is fed back to the power supply of the electromagnet to automatically demagnetize it. .

DESCRIPTION OF THE PREFERRED EMBODIMENTS A device for magnetizing and demagnetizing a magnetic bubble memory device according to the present invention and a method for manufacturing the same will be described in detail below with reference to the drawings.

FIG. 2 is a partial cross-sectional configuration diagram showing an example of a magnetic bubble memory device, particularly a magnetization/demagnetization device for a magnetic bubble memory device according to the present invention.

In the figure, 4 is an electromagnet, and between the pole pieces 4a of the electromagnet 4, there is a guide rail 6 on which a magnet block 5 having a magnet plate 2 closely arranged on the inner surface of the shield case 1 is attached, and a guide rail 6 at the center thereof. For example, G to sense a magnetic field
A magnetic sensing element 7 made of a semiconductor Hall element made of aAs is provided.

Two coils 8 are wound in series around the electromagnet 4, one end of which is grounded, and the other end of which is connected to a movable contact 9a of a changeover switch 9.

Further, the fixed contact 9b of this changeover switch 9 is connected to a magnetized power supply 10 whose one end is grounded, and the fixed contact 9c
is connected to the demagnetizing power supply 11 whose one end is grounded, and the fixed contact 9d is connected to the AC power supply 1 whose one end is grounded.
Connected to 2.

Further, the demagnetizing power source 11 includes a control section 13 that compares the output voltages of the electromagnet 4 and the magneto-sensitive element 7 with predetermined values.
is connected.

In the magnetization/demagnetization device configured as described above, first, the magnet block 5 in which the magnet plates 2 are arranged facing each other on the inner surface of the shield case 1 between the pole pieces 4a of the electromagnets 4 is mounted on the guardrail 6. A magnetic sensing element 7 is disposed in the center of the gap A, and is configured to be able to detect the bias magnetic field of the magnet block 5.

In such a configuration, the process of magnetizing and demagnetizing the magnet block 5, that is, the magnet plate 2, is as follows: (1) First, the movable contact 9a of the changeover switch 9 is switched to the fixed contact 9b, and a pulse width of 50 m5 is applied from the magnetizing power source 10. The magnetizing pulse current is supplied to the coil 8 of the electromagnet 4, and the magnet block 5 is magnetized to saturation.

(2) Next, switch the movable contact 9a to the fixed contact 9c side,
Supplying a demagnetizing pulse current to the coil 8 from the demagnetizing power supply 11,
The magnet block 5 is demagnetized to a predetermined value.

(3) At this time, the value of the bias magnetic field is detected by the magneto-sensitive element 7, and the demagnetization in (2) is performed until this value reaches the desired value.

In this case, the amplitude of the demagnetizing pulse current that is sequentially and repeatedly supplied increases at a constant rate of increase.

(4) Then, when the magnetic sensing element 7 detects the desired bias magnetic field value, the movable contact 9a is switched to the fixed contact 9d,
An alternating current is supplied from the alternating current power source 12 to the coil 8, and an alternating current is depleted by an alternating magnetic field to magnetically stabilize the magnetization and demagnetization of the magnet plate 2, thereby completing the magnetization and demagnetization of the magnet block 5.

In this case, the control unit 13 controls the application and timing of the magnetic field for magnetizing and demagnetizing the electromagnet 4, comparing the output voltage of the magneto-sensitive element 7 with a desired value, switching the changeover switch 9, etc.

This state will be explained in more detail using the timing diagram of the magnetization and demagnetization process shown in FIG.

In this figure, the horizontal axis represents the process time, and the vertical axis represents the magnetic field strength applied from the pole piece 4a to the magnet block 5.

In the figure, time t is reached by the step (1) above.

At this time, the magnetizing magnetic field Hm is applied once to perform saturation magnetization, and then the demagnetizing magnetic field Hd is sequentially applied in step (2) above.

In this case, this demagnetizing magnetic field Hd is applied at time t7. t2. t
3. Magnetic field for demagnetization Hct+, Hd2゜Hd3... whose magnetic field strength was increased little by little in accordance with changes in...
... is applied, and the magnetic field strength within the magnet block 5 is set at time t1. t2. When the value detected by the magneto-sensitive element 7 at time t3 becomes a desired value, for example, the value detected at time t4 is applied to the magnetic plate 2 by applying an alternating magnetic field according to the step (4) above. Magnetization stability is improved and demagnetization is completed at time t.

FIG. 4 is a timing diagram of the magnetization and demagnetization process showing another embodiment of magnetization and demagnetization of the magnet block according to the present invention.

In this figure, the difference from FIG. 3 is that the time t is changed due to the step (1) above.

In this case, after the magnetizing magnetic field Hm is applied to perform saturation magnetization, the demagnetizing magnetic field Hd is always applied.

In other words, the magnetizing magnetic field Hm and the demagnetizing magnetic field Hd are set at time tl.

12.13.... are applied alternately, and
The magnetic field strength of the magnetic field Hd for demagnetization is sequentially changed to Hd 1. Hd2
, Hd s..., and so on.

At this time, time 11+t2. At time t3..., the magnetic field strength within the magnet block 5 is detected by the magnetic sensing element γ, and for example, at time t4, when the detected value reaches a desired value, the alternating current is turned on by the step (4) above. A magnetic field is applied to stabilize the magnetization of the magnet plate 2, and the magnetization and demagnetization are completed at time t5.

Here, the magnetizing magnetic field Hm in the above embodiment.

The values of the demagnetizing magnetic fields Hd and Hd2-Hd are configured to be variable, and the values of the magnetizing magnetic field Hm, demagnetizing magnetic fields Hd and Hd2-Hd are set to appropriate values. Therefore, the magnetization and demagnetization process can be carried out in a few seconds.

For example, the magnetizing magnetic field Hm-=I0 is applied to the magnet block 5.
When applying 000 Gauss, magnetic field for demagnetization Hd = 3000 Oe, Hd2Ha = 30 Oe,
It was possible to magnetize and demagnetize in an extremely short time of 24 seconds on average to obtain the desired value of 105 oersteds.

Further, in this case, the values obtained for the set value of 105 oersted were in the range of 104.8 to 1051 oersted, and magnetization and demagnetization could be achieved with extremely high accuracy.

As explained above, according to the device for magnetizing and demagnetizing a magnetic bubble memory device and the method for manufacturing the same according to the present invention, it is possible to magnetize and demagnetize a magnet block that generates a static magnetic field in an extremely short time and with high precision. You can get the same effect.

[Brief explanation of the drawing]

Figures 1a and 1b are top views of essential parts showing an example of a magnet block;
FIG. 2 is a partial sectional view showing an example of the magnetization/demagnetization device for a magnetic bubble memory device according to the present invention; FIG.
The figure is a timing chart of the magnetization and demagnetization process showing an example of the method for manufacturing a magnetic bubble memory device according to the present invention, particularly the method for magnetizing and demagnetizing a magnet block. FIG. FIG. 1 is a timing chart 1 of the magnetization/demagnetization process showing another embodiment of the magnetization/demagnetization method. 1... Shield case, 2... Magnet plate, 3... Magnetic shunt plate, 4... Electromagnet, 4a
... Pole piece, 5 ... Magnet block, 6 ... Guide rail, 7 ... Magnetic sensing element, 8 ... Coil, 9 ......Selector switch, 9a...Movable contact, 9b, 9c, 9a.
...Fixed contact, 10... Magnetizing power supply, 11
... Demagnetizing power supply, 12 ... AC power supply, 1
3...Control section.

Claims (1)

[Scope of Claims] 1. An electromagnet around which an excitation coil is wound, a magnetic sensing element disposed between pole pieces of the electromagnet, a magnetization power source that supplies a magnetization pulse current to the excitation coil, A demagnetizing power supply that supplies a demagnetizing pulse current to an excitation coil, and an AC power supply that supplies an alternating current to the excitation coil, and a magnet block is disposed between the pole pieces of the electromagnet to demagnetize the magnet block. A device for magnetizing and demagnetizing a magnetic bubble memory device, characterized in that it is magnetized. 2 A magneto-sensitive element is arranged inside the magnet block, a demagnetizing field is applied after the magnet block is saturated and magnetized, and the strength of the static magnetic field inside the magnet block after the demagnetizing field is applied is detected by the magneto-sensitive element. A method for manufacturing a magnetic bubble memory device, characterized in that the above-mentioned magnetization and demagnetization process is repeated until the detected value becomes the desired value by comparison with a preset desired value. .