JPS599987B2 - Drive control method of magnetic bubble device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a magnetic bubble device, particularly a method for activating magnetic bubbles as needed.
The present invention relates to a drive control method for a magnetic bubble device that is stopped.

There is a method of driving a magnetic bubble using a rotating magnetic field and a pattern of soft magnetic material such as permalloy formed on the surface of a magnetic bubble element (magnetic bubble chip).

This is a method in which a permalloy pattern, such as a T-bar pattern, is formed by vapor deposition or sputtering on a crystal plane where magnetic bubbles can exist, and a rotating magnetic field is applied from the outside in the direction within the crystal plane. The rotating magnetic field is usually obtained by passing sine wave current, triangular wave current, or trapezoidal wave current having a phase difference of 900 degrees through each of an X coil and a Y coil arranged perpendicularly around the magnetic bubble chip. The magnetic bubble is transferred along the soft magnetic material pattern by the action of this rotating magnetic field. When the rotating magnetic field comes to rest, the magnetic bubbles come to rest at pattern positions corresponding to the direction of rest of the rotating magnetic field. In the magnetic bubble device, starting and stopping of the rotating magnetic field is frequently repeated in response to information writing, reading, shifting operations, and the like. usually,
Various functional elements such as a magnetic bubble generator, propagation path, divider, stretcher, magnetic bubble detector, and eraser are arranged on the magnetic bubble chip, and as mentioned above, information can be written, read, and shifted. When the rotating magnetic field is started and stopped as appropriate depending on the operation, the expanding magnetic bubbles, especially those located under the stretcher and magnetic bubble detector patterns, shrink when the rotating magnetic field stops. Even if the rotating magnetic field is subsequently activated again, this reduced magnetic bubble will reach the detector pattern without being extended to the initially set sufficient length, and therefore, in this case, the same detection output as during continuous operation will be obtained. I can't. In particular, magnetic bubble devices operate under a high bias magnetic field to improve storage density, so a magnetic bubble that is activated under a detector pattern or a stretcher pattern of several bits just before the detector pattern is fully expanded. Can not do it. For this reason, in conventional magnetic bubble devices of this kind, the rotating magnetic field is controlled so as not to stop while the stretched magnetic bubble is present in the magnetic bubble detecting section consisting of a detector and a stretcher, or Immediately after the rotating magnetic field was activated, magnetic bubbles were not detected, and the system was controlled to wait until the same information was transferred again.

However, the magnetic bubble device that performs the above-mentioned control has drawbacks such as a complicated control system, an inability to effectively utilize a storage loop, and a long access time. The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a drive control method for a magnetic bubble device that can effectively utilize a storage loop.

Another object of the present invention is to provide a drive control system for a magnetic bubble device that can obtain a detection output equivalent to that during continuous operation immediately after starting a rotating magnetic field, and can therefore shorten access time.

A feature of the present invention that achieves the above object is that it includes a bubble element including a detection section that extends and detects a magnetic bubble, means for applying a bias magnetic field to the bubble element, and means for applying a rotating magnetic field to the bubble element. In a system for controlling the drive of a magnetic bubble device, the rotating magnetic field applying means is controlled so that the rotating magnetic field applied to the bubble element makes at least one reciprocating motion at the time of activation.

This will be explained in detail below using the drawings.

FIG. 1 is an example of a pattern of a magnetic bubble detection section whose drive is controlled by the heather invention method.

In this figure, 1 is a serpentine pattern magnetic bubble detector using magnetoresistive effect, 2a, 2b
is a terminal for supplying current to the detector 1 and taking out a detection signal. Reference numeral 3 denotes a stretcher 1 for stretching the magnetic bubble in a direction perpendicular to its traveling direction to improve detection sensitivity, and in this example, it is composed of a multi-stage chevron pattern.

Further, 4 indicates a transfer path for guiding the magnetic bubbles to the detection section. FIG. 2 is a circuit configuration diagram showing an embodiment of the driving magnetic field generating section according to the present invention, in which 5 is a magnetic bubble chip equipped with a detection section as shown in FIG. 1, and 6 and 7 are rotating magnetic fields within the plane of the chip. These drive coils 6 and 7 are arranged orthogonally to each other. 8 is a drive current generation circuit for the X drive coil 6, and 9 is a drive current generation circuit for the Y drive coil 7.

The drive current generating circuits 8 and 9 each include switch elements Sl, S2, S3, S4 and switch elements S1', S2', S3', S4' connected as shown in FIG. A desired rotating magnetic field can be obtained by controlling the elements as shown in FIGS. 3C and 3D by a well-known control circuit (not shown). Figure 3 A, B,
C and D are diagrams for explaining the operation of the drive magnetic field generator shown in FIG.
B is the locus of the in-plane rotating magnetic field formed in the chip 5 by this drive current waveform, and C and D are control time charts of each switch element of the drive current generation circuits 8 and 9. It shows the relationship with each drive current generated by the control.

In addition, the symbols A, b, c, b', in the above diagrams B, C, and D
c', b'', c'', E, f, and g represent the temporal coincidence of each current waveform and rotating magnetic field locus. At time a, when switch elements S1 and S3 are turned on, current begins to flow through the path of switch element Sl, X coil 6, and switch element S3.

This current gradually increases according to a time constant determined by the inductance and internal resistance of the X coil, and gradually decreases according to the time constant when switch elements S1 and S3 are turned off at time b. At time C, the switch element S
1 and S3 are turned on and turned off at time b'.
Further, at times ♂ and B, switch elements S1 and S3 are turned on and off. Next, when switch elements S2 and S4 are turned on at time c'', a triangular wave current in the opposite direction flows through the X coil 6.On the other hand, on the Y coil side, that is, in the drive current generation circuit 9, switch elements S1', S2', and
3', and S4' are switch elements S1', S2', and S3
And it operates in the same way as the x coil side until time f, delayed by T/4 with respect to S4. Therefore, the locus of the vector sum of the triangular wave current supplied from these generating circuits and the magnetic field excited by the actions of the x coil 6 and the Y coil 7 is as shown in FIG. 3B. Note that T above represents the period of the triangular wave current. Although the embodiments explained in FIGS. 2 and 3 use triangular wave currents whose phases differ from each other by T/4 as the drive current, the drive current in the present invention is not limited to triangular wave currents, but is, for example, a sine wave current. , or a trapezoidal wave current. In addition to the driving magnetic field generator shown in FIG. 2, the magnetic bubble chip 5 is also provided with a well-known via permanent magnetic field supply made of, for example, a permanent magnet, which applies a static magnetic field perpendicular to the chip in order to create a stable magnetic bubble. Needless to say, means are provided.

Now, the driving magnetic field as shown in Fig. 3B, that is, immediately after starting,
When a driving magnetic field that reciprocates in the rotational direction is applied to the magnetic bubble detector as shown in Fig. 1, the magnetic bubbles reciprocate back and forth on the stretcher or the detector (hereinafter referred to as a warming-up operation). Then perform the normal propagation operation. The magnetic bubble, which had shrunk due to the stoppage of the rotating magnetic field, is expanded to a sufficient length in the direction perpendicular to the propagation direction by this warming-up operation. Therefore, by detecting this magnetic bubble, it is possible to obtain a detection output comparable to that during continuous operation. The driving magnetic field shown in FIG. 3 performs the warming-up operation from time b to time b''2, that is, the warming-up time is T (one cycle).
There is a fourth period between this warming-up time and the detection output.
There is a relationship as shown in the experimental results shown in the figure.

In Figure 4, the horizontal axis shows the warming-up time in units of period T, and the vertical axis shows the bias magnetic field. In this figure, h represents the bias magnetic field operating margin width during continuous operation, and i represents the warming-up time This indicates the upper limit of the bias magnetic field margin at which the detection output due to the up-operation is approximately the same value as during continuous operation. By performing this warm-up operation for several cycles, it is possible to obtain the same detection output as during continuous operation within a short time after starting the rotating magnetic field, that is, within the time required to transfer several bits, without changing the value of the bias magnetic field. be able to. Therefore, even if a magnetic bubble that has shrunk due to the stoppage of the rotating magnetic field exists in a portion of the detector or stretcher, this magnetic bubble information can be immediately and easily detected at startup, reducing access time. Furthermore, since information can be stored in a portion of the stretcher, the information storage area within the chip can be used effectively. FIGS. 5A to 5A are trajectory diagrams showing various embodiments of the driving magnetic field used in the method of the present invention.

In addition to the embodiment shown in FIG. 5, various other driving magnetic fields can be applied to achieve the above-mentioned warming-up operation. As described above, the magnetic bubble that has shrunk due to the stoppage of the rotating magnetic field is expanded by the warming-up operation, but the effect of this warming-up operation differs depending on the stopping position of the magnetic bubble.

FIG. 6 shows experimental results showing the relationship between the bias magnetic field operation margin and the magnetic bubble resting position when a warming-up operation is performed. In FIG. 6A, the vertical axis represents the bias magnetic field, and the horizontal axis represents the warming-up time in units of period T of the drive current, and each line J, k in the figure
, l, m, and n represent the experimental results when the rotating magnetic field was set to 70 (0e). In addition, the table shown in Figure 6B shows the position of the magnetic bubble during the warming-up operation, that is, where the magnetic bubble is present in the stretcher pattern and the detector pattern during the warming-up operation. This explains the trajectory of a rotating magnetic field. The symbols j to n on this table are assigned corresponding to the lines j to n in FIG. 6A. Note that each of the above-mentioned lines j to n in FIG. 6A represents the upper limit of the bias magnetic field margin when the detection output from the detector becomes approximately the same value as the detection output during continuous operation. Further, the symbol p in the figure represents the upper limit of the bias magnetic field margin during continuous operation. As is clear from this figure, it is better to perform the warming-up operation of the magnetic bubble when starting the rotating magnetic field under a stretcher pattern like J, k, and l, than to do it under a detector pattern like M and n. The upper limit of the bias magnetic field margin becomes higher. Therefore, for example, when the value of the bias magnetic field is set to 170 (0e) and the magnetic bubble is driven under the bias magnetic field, if the magnetic bubble undergoes a warming-up operation under the stretcher pattern (J,
In the case of k, l), the warm-up time may be around 1 [T], but if the warm-up operation is performed under the detector pattern (in the case of M, n), a warm-up time of 4 [T] or more is required. That is, if the rotating magnetic field is controlled when stopping so that the tip of the magnetic bubble information stops at a part of the stretcher immediately in front of the detector, and the warming-up operation at startup is performed in a part of the stretcher, the warming-up time can be shortened and access can be improved. You can further improve your time. As explained above, according to the method of the present invention, it is possible to effectively utilize storage loops and shorten access time, and the effects of the present invention are very large.

[Brief explanation of drawings]

FIG. 1 is a pattern diagram of a magnetic bubble detection section to which the present invention is applied, FIG. 2 is a circuit diagram of an embodiment of a driving magnetic field generating section of the present invention, and FIG. 2 is an operation explanatory diagram, FIG. 4 is a bias magnetic field margin characteristic diagram with respect to warming-up time, FIGS. 5 A to 0 are locus diagrams showing examples of various rotating magnetic fields used in the method of the present invention, and FIG. 6 A
, B are bias magnetic field margin characteristic diagrams and their explanatory diagrams with respect to the warming-up operation position. 1...Magnetic bubble detector, 2a, 2b...
...Terminal, 3...Stretcher 1, 4...
...Transfer path, 5...Magnetic bubble chip, 6,7
... Drive coil, 8, 9... Drive current generation circuit.

Claims (1)

[Claims] 1. The rotating magnetic field applying means of a magnetic bubble device comprising a bubble element including a detection section that extends and detects a magnetic bubble, means for applying a bias magnetic field to the bubble element, and means for applying a rotating magnetic field to the bubble element. In a drive control method in which the rotating magnetic field applied to the bubble element performs at least one reciprocating motion at the time of startup by controlling A drive control method for a magnetic bubble device, which is characterized in that it is controlled so that it is located at the stretcher section immediately in front of it.