JPS6142344B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to magnetic bubble storage elements, and more particularly to improvements in the magnetic bubble detector field.

The important functional parts of the magnetic bubble memory element include a detector and a magnifier. The detector used to read stored information usually uses a magnetoresistive element that detects the leakage magnetic field from a magnetic bubble, but a single circular magnetic bubble cannot generate enough magnetic field to detect it. Since this is not possible, a magnifying device is required to enlarge the magnetic bubble to a length several hundred times the diameter before detection. Since the detection output increases in proportion to the expanded length of the magnetic bubble, it is possible to obtain a practical detection output by providing an expander.

Various pattern structures have been proposed for magnetic bubble expanders, but at present, the so-called multi-stage chevron expander, which essentially consists of a chevron-shaped permalloy pattern, has been widely adopted. When expanding a magnetic bubble using a multi-stage Chevron expander, it is not possible to increase the size by several hundred times in one step due to the domain wall mobility, so a method of sequential expansion as shown in FIG. 1 is used. FIG. 1 is a block diagram of a magnifying device and a detector (hereinafter referred to as the detector region) of a conventional magnetic bubble memory element, in which 1 indicates a transfer path;
2 indicates a Chevron magnifier, and 3 indicates a detector.

However, as can be seen from FIG. 1, expanding the magnetic bubble to the detector length L requires many Chevron patterns 2, which increases the area occupied by the detector region within the element. Therefore, it is not possible to provide a large number of detector regions in one element, and the number of detector regions is usually one to two, or at most four. As storage elements become larger in capacity, their architectures become more diverse. For example, in order to achieve high-speed readout, it is necessary to provide many detectors in one element, and to do so, the detector area must be made smaller. . If this can be achieved, the degree of freedom in design will increase and it will be possible to prevent performance deterioration due to increased capacity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic bubble storage element that occupies a small unit detector area.

A feature of the present invention is that in a magnetic bubble storage element comprising at least a magnetic bubble expander and a detector, the expander is provided under a first expander made of a permalloy pattern and a layer below the first expander. and a second magnifying device made of a conductive pattern, and the detector is a magnetic bubble storage element that detects the magnetic bubble expanded by the first and second magnifying devices. Further, the magnification operation phase of the second magnifier and the detection operation phase of the detector are in the same rotating magnetic field period in the magnetic bubble storage element.

The reason why the expander of the conventional configuration shown in FIG. 1 has to occupy a large area and expand sequentially is that there is a limit to the mobility of the magnetic bubble domain wall. The maximum domain wall movement speed in a garnet material with a magnetic bubble diameter of around 1 to 2 μm is about 30 to 40 m/sec, so if a sufficient magnetic field gradient is given, it can be moved within a few μsec, which means that the normally used magnetic frequency is around 100 KHz. It is possible to expand to the required length within one period of the rotating magnetic field. However, since the maximum domain wall velocity cannot be obtained only with the magnetic field gradient induced by the Chevron expander, we have no choice but to use a method of successively expanding the magnetic field over several tens of periods of the rotating magnetic field.

The present invention provides a first expander made of a permalloy pattern, such as a Chevron expander, and a second expander made of a conductor in the lower layer of this expander,
This is accomplished by applying a current pulse to the second expander to provide a sufficient magnetic field gradient to the magnetic bubble.

The present invention will be explained in detail below using the drawings. FIG. 2 is a block diagram showing a detector area of a first embodiment of a magnetic bubble storage element according to the present invention.

When the magnetic bubbles transferred from the right direction in FIG. 2 through the transfer path 1 at a transfer period of 10 μsec reach the first enlarger 21 of the 50-stage Chevron made of permalloy pattern, the Chevron pattern is induced by the rotating magnetic field. It begins to expand due to the magnetic field gradient. When this magnetic bubble reaches the center of the hairpin-shaped second magnifying device 4 made of a conductive pattern, the second magnifying device 4 is arranged so that the vertical bias magnetic field at that portion becomes small.
A current pulse with a width of 3 μsec is applied to. Due to this current pulse, the magnetic bubble, which had begun to partially expand, is expanded all at once to the entire length of the first expander 21. Once the magnetic bubble has been expanded, it remains expanded to its full length even after the current pulse is removed, and is transferred to the subsequent Chevron expander 22, reaches the detector 3, and is detected. As described above, conventionally it took several tens of cycles to reach the detector after entering the detector, but according to this embodiment, it only takes two cycles, and the area of the detector region is significantly reduced.

FIG. 3 is a block diagram showing the detector area of a second embodiment of the magnetic bubble storage element according to the present invention. The difference from the first embodiment shown in FIG. 2 is that the detector 3
is placed within the hairpin loop of the second expander 4. That is, the magnetic bubble is simultaneously expanded to the entire length of the first expander 21 by the current pulse applied to the second expander 4, and detected by the detector 3 at the same time. FIG. 4 shows the timing within the cycle of the functional units related to this series of operations. FIG. 4 shows the respective temporal relationships among the rotating magnetic field, the detection output waveform, the detection strobe pulse, and the current pulse flowing through the second enlarger 4 in the embodiment shown in FIG. 2, in which order a, b, c , d. According to this embodiment, the required transfer cycle from entering the magnifier to reaching the detector is one cycle, and the area of the detector region is further reduced than in the first embodiment.

As explained above, according to the present invention, the area of the detector region can be significantly reduced, and many detectors can be provided in one element, making it possible to improve the layout design of large-capacity, high-performance magnetic bubble memory elements. This increases the degree of freedom and is industrially beneficial.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a detector area used in a conventional magnetic bubble memory element, and FIGS. 2 and 3 are detector areas in magnetic bubble memory elements according to the first and second embodiments of the present invention. FIG. 4 is a diagram showing the temporal relationship of the driving states of the magnetic bubble storage element according to the second embodiment of the present invention. In the figure, 1... transfer path, 2, 21, 2
2...first magnifier, 3...detector, 4...second
It is a magnifier.

Claims (1)

[Scope of Claims] 1. A magnetic bubble storage element comprising at least a magnetic bubble expander and a detector, wherein the expander is a first expander made of a permalloy pattern and a layer below the first expander. a second magnifying device made of a conductive pattern, and the detector is a detector for detecting magnetic bubbles magnified by the first and second magnifying devices. Bubble memory element. 2. The magnetic bubble storage element according to claim 1, wherein the enlargement operation phase of the second enlarger and the detection operation phase of the detector are within the same rotating magnetic field period.