JPS6151407B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetization method for setting a bias magnetic field necessary for a storage operation of a magnetic bubble module, particularly a magnetic bubble chip.

Conventionally, the method of magnetizing this type of magnetic bubble module is to apply a very strong magnetizing magnetic field to the permanent magnet from the outside to the magnetic bubble module, which has a permanent magnet inside, to achieve saturation magnetization. , Apply a demagnetizing magnetic field in the opposite direction to the saturation magnetizing magnetic field to reduce the magnetization strength of the permanent magnet to the bias magnetic field value necessary for the memory operation of the magnetic bubble chip, and then apply a slight alternating magnetic field. There are magnets designed to stabilize the magnetization of permanent magnets. This method was used, for example, in 1976.
IE Transactions on Magnetics (IEEE
Transactions on Magnetics). Volume 12, No. 6
No. 645-647.

However, in the above-described magnetization method, the bias magnetic field value set by the demagnetizing magnetic field is shifted by the alternating magnetic field applied subsequently, so that the bias magnetic field cannot be set with high precision.

Another drawback is that the amplitude of the permissible external disturbance magnetic field within the range that ensures the stability of magnetization of the permanent magnet is small.

Further, the above-mentioned document does not describe any means for checking whether the bias magnetic field is set correctly.

A first object of the present invention is to provide a magnetization method that eliminates the above-mentioned drawbacks and sets a bias magnetic field with high precision.

A second object of the present invention is to provide a magnetization method that can realize a magnetic bubble module that is highly stable against external disturbing magnetic fields.

A third object of the present invention is to provide a magnetization method in which magnetization is performed while confirming a set bias magnetic field.

A fourth object of the present invention is to provide a magnetizing device that achieves the above-mentioned magnetizing method.

In the magnetization method of the present invention, after the permanent magnet in the magnetic bubble module is saturated and magnetized, it is demagnetized by an attenuating alternating demagnetizing magnetic field, and a bias current is supplied to the Z coil that applies a bias magnetic field perpendicular to the magnetic bubble chip. The amount of magnetization of the permanent magnet is set so that normal storage operation is possible in this state.

This will be explained in detail below using the drawings.

FIG. 1 shows an example of a magnetic bubble module to which the magnetization method of the present invention is applied. Inside the magnetic shield case 11, between two sets of composite plates consisting of a permanent magnet plate 12 and a magnetic shunt plate 13, there is a memory plane 16 in which an in-plane rotating magnetic field drive coil is wound around a magnetic bubble chip, and a magnetic bubble chip. A Z coil 17 that generates a bias magnetic field in a direction perpendicular to is housed. Lead wires from the magnetic bubble chip and the drive coil are taken out from the gap in the magnetic shield case 11. The lead wires are omitted in the figure because they are complicated.

In order to perform normal storage operation of the magnetic bubble chip in such a magnetic bubble memory, the permanent magnet plate 12 must be magnetized as shown by the arrow, and an appropriate bias magnetic field H _B in the direction 14 must be applied. Must be.

An appropriate bias magnetic field value is, for example, a diameter of 3μ.
In the case of a bubble chip giving a bubble diameter of m, the center value of the bias magnetic field (in this case
180Oe). The allowable amount of deviation from the center value ±10 Oe is the storage operation margin width, and if the deviation from the center value of the applied bias magnetic field is within this range, normal storage operation can be performed.

FIG. 2 shows the magnetic field pattern employed in the magnetization method of the present invention used to set a bias magnetic field in the magnetic bubble module.

The difference from conventional magnetization methods is that the demagnetization and demagnetization operations after saturation magnetization are simplified to demagnetization operations using an attenuating alternating demagnetization magnetic field. FIG. 2 shows a saturation magnetizing field 230 in direction 14 and an attenuating alternating demagnetizing field 240 in direction 14 and its opposite direction. The amplitude of the saturation magnetizing magnetic field 230 is approximately 10 kOe
The amplitude of the alternating demagnetizing magnetic field 240 is several kOe or less.
The generation of an alternating demagnetizing magnetic field in this case can be easily limited by constructing a resonant circuit with an excitation coil and a capacitor charged to an accurate voltage value corresponding to the amplitude of the alternating demagnetizing magnetic field. Since the charging voltage of the capacitor can be controlled with high precision, bias magnetic field setting accuracy of 0.5 Oe or less can be easily achieved. Since the alternating demagnetization field amplitude serves both as a magnetic field for demagnetizing the permanent magnet and as a stabilizing field for the disturbance magnetic field, the disturbance magnetic field amplitude can be tolerated up to several kOe, making it much more stable than before. A magnetic bubble module can be obtained. It is sufficient that the number of alternations in the alternating demagnetizing magnetic field 240 is five or more.

FIG. 3 shows the relationship between the bias magnetic field H _B in the magnetic bubble module set by the magnetization method of the present invention and the amplitude H _D of the initial magnetic field in the opposite direction to the bias magnetic field in an alternating demagnetizing magnetic field; That is, it shows magnetization characteristics. Point S is the bias magnetic field value H immediately after saturation magnetization.
_BS , but if the amplitude H _D of the demagnetizing magnetic field is increased, a bias magnetic field with a smaller value than H _BS can be obtained. For example, due to a demagnetizing field with an amplitude H _D1 , the amplitude H _B1
The bias magnetic field can be set to a bias magnetic field of 1, and the bias magnetic field H _B1 is extremely small with respect to an external disturbing magnetic field that does not exceed this H _D1 , and the magnetization of the permanent magnet is stable.

The center value of the operating bias magnetic field of the chip in the magnetic bubble module is H _B0 , and ±ΔH from the center value.
When the chip operates with a bias magnetic field within the range of _B0 , the module is magnetized by determining the amplitude of the alternating demagnetizing magnetic field from the magnetization characteristics so that the set bias magnetic field has a value near H _B0 . . Since there may be some deviation between H _B0 and the value of the set bias field, positive and negative bias currents are supplied to the Z coil to produce a variation of ±ΔH _BZ from the set value of the bias field, but still If normal storage operation is performed, it can be confirmed that the deviation is not large. Note that ΔH _BZ with respect to the bias current value of the Z coil is smaller than ΔH _B0 and is determined based on the specifications of the module.

However, because the center value of the operating bias magnetic field of a magnetic bubble chip cannot always be accurately measured, and because multiple chips are incorporated in the magnetic bubble module, it is difficult to measure the amplitude of the attenuating alternating demagnetizing magnetic field _HD . Often cannot be determined unambiguously.
To deal with this, a magnetization method is needed that can set the optimum bias magnetic field for the chip by applying an attenuating alternating demagnetizing magnetic field multiple times after saturation magnetization.
Operating bias magnetic field center value H _B0 and merging width ±ΔH
The method of magnetizing a module incorporating a _B0 chip will be explained with reference to the magnetization characteristics shown in FIG.

After saturation magnetization, first demagnetization is performed using a demagnetizing magnetic field having an amplitude H _D1 and the bias magnetic field of the module is set to H _B1 . In this state, positive and negative bias currents are supplied to the Z coil to cause the module to perform a memory operation. As a result, although the bias magnetic field fluctuates by ±ΔH _BZ from the set bias magnetic field, normal storage operation does not occur. Next, demagnetization is performed using a demagnetizing magnetic field with an amplitude of H _D2 , and the bias magnetic field of the module is changed to H _B2.
Set to . Even if a bias current is supplied to the Z coil as before to cause the module to perform a memory operation, a normal memory operation still does not occur.

The amplitude of the demagnetizing magnetic field is further increased, demagnetizing is performed by the demagnetizing magnetic field having the amplitude H _D3 , and the bias magnetic field of the module is set to H _B3 . In this case, you can either supply a positive bias current with a predetermined amplitude to the Z coil and set the bias magnetic field to H _B3 +ΔH _BZ , or supply a negative bias current with the same amplitude. Even if the bias magnetic field is set to H _B3 −ΔH _BZ ,
When the module performs the memory operation, it is possible to confirm that the memory operation is normal. At this point, further application of the demagnetizing magnetic field is stopped, and the setting of the bias magnetic field is completed.

When setting the module's bias magnetic field using this magnetization method, it is important to shorten the magnetization time by minimizing the number of times the demagnetizing field is applied until the module is set to the optimal bias magnetic field. , and the chip operating bias magnetic field width 2ΔH
It is important to be able to set the module's bias magnetic field even if _{the BO} is narrow.

When the module is magnetized according to FIG. 4, the amount of increase in the amplitude of the demagnetizing magnetic field, _HD1 -0, _{HD2 -HD1} ,
If magnetization is performed by fixing H _D3 -H _D2 to a predetermined amount, there is an advantage that the magnetizing device becomes simple.
However, a fixed amount of increase must be determined corresponding to ΔH _B0 , and if the minimum allowable value of ΔH _B0 is selected to be small, the number of times the demagnetizing magnetic field is applied will increase.

In order to reduce the number of applications, the first
It is also possible to make the amount of increase in the demagnetizing magnetic field for the first time, that is, H _D1 , larger than the amount of increase thereafter, and to set the amount of increase in the demagnetizing magnetic field for the second and subsequent times to a constant value corresponding to ΔH _B0 . In this case, checking by the memory operation after the first demagnetization can be omitted.
As another magnetization method, the amount of increase in the amplitude of the demagnetizing magnetic field can be made to decrease monotonically with the number of demagnetizing operations.

Another method of magnetization is to detect the deviation between the center value of the operating bias magnetic field of the chip and the bias magnetic field set in the module using a bias current flowing through the Z coil, and demagnetize the chip based on the amount of this deviation. There is a magnetization method that determines the amplitude of the magnetic field. This magnetization method will be explained with reference to FIG. After saturation magnetization, first, it is demagnetized with a demagnetizing magnetic field having an amplitude _HD1 , and the bias magnetic field H _B1 of the module to be set is set to a value slightly larger than the upper limit of the bias magnetic field (H _B0 +ΔH _B0 ) of the chip. After that, a negative bias current is supplied to the Z coil to adjust the set bias magnetic field H _B1 and the upper limit (H _B0 +ΔH _BO ) and lower limit (H B0 ) of the chip bias magnetic field.
_B0 −ΔH _B0 ) is measured. Based on this value, the amplitude H _D2 of the demagnetizing magnetic field is determined, and the bias magnetic field of the module is set to H _B2 . By doing this, H _B2 can be set to approximately the same value as the bias magnetic field center value H _B0 of the chip. After setting, supply bias current to the Z coil to confirm normal memory operation of the module.

This magnetization characteristic may differ depending on the module, so depending on the deviation between the operating bias magnetic field center value and the set bias magnetic field, the bias magnetic field can be changed by one demagnetizing operation after the demagnetizing operation with the amplitude H _D1 . Instead of setting, the amplitude may be set slightly lower than the amplitude of the demagnetizing magnetic field determined according to this deviation, and the demagnetizing operation may be performed multiple times.

In this case, the first swing width _HD1 may also be determined according to the deviation.

Although two main methods of magnetizing the module have been described above, a method of magnetizing the module that is a mixture of these two methods is also conceivable. Furthermore, the magnetic bubble module to which the magnetization method of the present invention is applied is not limited to the one shown in FIG. can.

FIG. 6 shows a magnetizing device based on the magnetizing method of the present invention. A magnetization yoke 6 around which an excitation coil 61 is wound for applying a magnetic field to the magnetic bubble module 60 to be magnetized to set a bias magnetic field.
2, and an exciter 63 that supplies current to the excitation coil 61 to generate the magnetic field pattern shown in FIG.
, a bias current circuit 64 that supplies positive and negative bias currents to the Z coil of the module, a peripheral circuit 65 including peripheral circuits of the module, that is, a coil driver, a function driver, a sense circuit, etc., and FIGS. It consists of a control circuit 66 that controls an exciter 63, a bias current circuit 64, and a peripheral circuit 65 so that magnetization is performed according to the magnetization method explained based on FIG.

In the exciter 63, the charges accumulated in the capacitor 76 from the DC power source 71 with variable output voltage through the resistor 72 and the closed switch 73 are discharged to the exciting coil 61 by closing the switch 75. At this time, switch 73 is open. When discharging, switch 7
Two types of current flow depending on the opening and closing of excitation coil 6.
1. That is, if the switch 74 is closed, a current that generates the saturation magnetizing magnetic field 230 shown in FIG. 2 is supplied to the exciting coil 61. On the other hand, if the switch 74 is open, a current is supplied to the excitation coil 61 to generate the demagnetizing magnetic field 240 of FIG.

In this case, the output voltage of the DC power supply 71 is changed according to the amplitudes of the magnetic fields 230 and 240 to supply current to the exciting coil 61.

Since the peripheral circuit 65 is connected to the magnetic bubble module 60, the storage operation of the module 60 is performed by the control circuit 66. Even if predetermined positive and negative bias currents are supplied from the bias current supply circuit 64 to the Z coil of the module 60 and a bias magnetic field variation of ±ΔH _BZ is applied to the set bias magnetic field, the memory operation is normal. In other words, the magnetization for setting the bias magnetic field to the module 60 has been completed. Generally, if specific write information is written, then a read operation is performed, and the sense circuit in the peripheral circuit 65 detects that the read information matches the write information, it is determined that the memory operation of the module 60 is normal. Ru.

As explained above, according to the present invention, it is possible to easily solve the disadvantage of low bias magnetic field setting accuracy, which was a problem with conventional magnetization methods, and to create a magnetic bubble module that is highly stable against external disturbing magnetic fields. A Yule magnetic field can be provided, and it can be checked whether the bias magnetic field set by the magnetization of the module is optimal.

Note that the Z coil shown in the embodiment is an example of a case where it is built in the module, but the present invention is not limited to this, and it may be placed outside or may be detachable.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a magnetic bubble module to which the present invention is applied, FIG. 2 is a magnetic field pattern in the method of magnetizing a magnetic bubble module of the present invention, and FIG. 3 is a magnetizing method of the present invention. FIGS. 4 and 5 are magnetizing characteristics for explaining the magnetizing method of the present invention, and FIG. 6 is a circuit diagram showing an embodiment of the magnetizing apparatus of the present invention. 12 is a permanent magnet plate inside the module, 14 is a bias magnetic field direction inside the module, 17 is a Z coil,
230 is a magnetic field for saturating the permanent magnet, 2
40 is an alternating demagnetizing magnetic field, 60 is a magnetic bubble module, 61 is a magnetizing yoke, 62 is an excitation coil, 63
64 is an exciter, 64 is a bias current circuit, 65 is a peripheral circuit, and 66 is a control circuit.

Claims (1)

[Scope of Claims] 1. A method for magnetizing a magnetic bubble module comprising a magnetic bubble chip, a drive coil that generates an in-plane rotating magnetic field, and a permanent magnet that supplies a bias magnetic field perpendicular to the magnetic bubble chip, After the permanent magnet is saturated and magnetized in a first direction, an alternating demagnetizing magnetic field that attenuates in the first direction and a second direction opposite thereto is applied to the permanent magnet, and the bias magnetic field direction is applied within the bubble module. The memory operation of the module is performed while predetermined positive and negative bias currents are supplied to the Z coil, which can generate a magnetic field of A method for magnetizing a magnetic bubble module, comprising setting the amount of magnetization of the permanent magnet to enable operation. 2 The amount of magnetization of the permanent magnet is set by applying a demagnetizing magnetic field and storing the module while supplying predetermined positive and negative bias currents to the Z coil. The method of magnetizing a magnetic bubble module according to claim 1, which is carried out by repeating the demagnetization while slightly increasing the amplitude of the magnetic field until the demagnetization becomes possible. 3 The amplitude of the first demagnetizing magnetic field applied to the permanent magnet is a predetermined value, and the amplitude of the demagnetizing magnetic field applied thereafter is the bias current value to the Z coil that enables normal operation of the module. A method of magnetizing a magnetic bubble module according to claim 2, which is determined depending on the following. 4. The magnetic bubble module according to claim 3, wherein the amplitude of the first demagnetizing magnetic field applied to the permanent magnet is determined depending on the bias current value to the Z coil that enables normal operation of the module. Yule magnetization method. 5. A magnetization device with an excitation coil that fixes a module containing a magnetic bubble chip, a drive coil that generates an in-plane rotating magnetic field, and a permanent magnet that supplies a bias magnetic field perpendicular to the magnetic bubble chip, and supplies a uniform magnetic field to the module. a yoke, a Z coil capable of generating a magnetic field in the direction of the bias magnetic field within the bubble module, a first drive current and an attenuating alternating demagnetizing magnetic field that generates a saturation magnetizing magnetic field in the magnetizing yoke; an exciter that supplies a second drive current that generates a current, a bias current circuit that supplies positive and negative currents to the Z coil, and a peripheral circuit that causes the magnetic bubble module to memorize and detect whether the operation is normal or abnormal. A magnetizing device for a magnetic bubble module, characterized in that it is configured to include the exciter, the bias current circuit, and a control circuit for controlling peripheral circuits.