JPS6216467B2 - - Google Patents

Description

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

Important functional parts that are components of a magnetic bubble storage element include a magnifier and a detector. 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. After detection, the expanded magnetic bubble is usually rejected outside the guardrail.

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 expand the bubble hundreds of times all at once due to domain wall mobility, so a method of sequential expansion as shown in FIG. 1 is used. FIG. 1 is a configuration diagram of a magnifier and a detector (hereinafter referred to as the detector area) of a conventional magnetic bubble memory element, where 1 is a transfer path, and 2
indicates a Chevron enlarger, 3 indicates an enlarger, and 4 indicates a guardrail.

However, as seen in Figure 1, it takes many chevron patterns 2 to expand the magnetic bubble to the length of the detector.
This increases the area occupied by the detector area within the element, and the guardrail 4 is required to reject the enlarged magnetic bubble, which increases the area occupied by the detector area within the element. It has the disadvantage that it has to be placed near the periphery of the device due to restrictions. 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 have become larger in capacity, their architectures have also become more diverse. For example, in order to achieve high-speed readout, it is necessary to provide a large number of detectors in one element and at arbitrary positions. It has to 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 memory element that has a small unit area and a detector area that does not require a guardrail.

The present invention is characterized by a magnetic bubble storage element comprising at least a magnetic bubble expander, a detector, and an extinguisher, wherein the expander includes a first expander made of a permalloy pattern and a lower layer of the first expander. a second magnifying device made of a conductive pattern laid down in The present invention is a magnetic bubble storage element which is an extinguisher made of a conductive pattern laid under the first magnifying device that extinguishes the magnetic bubble detected by the detector. Further, the second expander and the extinguisher may be made of the same conductive pattern.

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, that is, at the normally used driving frequency of 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, a method must be used in which the magnetic field is expanded sequentially over several tens of cycles 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,
By applying a current pulse to the second expander and applying a sufficient magnetic field gradient to the magnetic bubble, it is quickly expanded.After detection, a current pulse is sent to the annihilator made of a conductor laid under the first expander. This is achieved by causing the magnetic bubble to disappear.

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. The magnetic bubbles transferred from the right direction in Figure 2 through transfer path 1 at a transfer cycle of 10 μsec are composed of permalloy patterns.
When reaching the first expander 21 of the 50-stage Chevron, it begins to expand due to the magnetic field gradient of the Chevron pattern induced by the rotating magnetic field. When this magnetic bubble reaches the center of the hairpin-shaped second expander 4 made of a conductive pattern, the second expander 4 has a width of 3 μm so that the vertical bias magnetic field at that part becomes small.
A current pulse of sec is applied. 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. The detected magnetic bubble is transferred to the subsequent Chevron expander 23, and when it reaches the center of the hairpin-shaped annihilator 5 made of a conductive pattern, the annihilator 5 is arranged so that the vertical bias magnetic field at that part becomes large. A current pulse with a width of 3 μsec is applied to. The magnetic bubble that had been expanding due to this current pulse shrinks and disappears. In this way, conventionally it took several 10 cycles from entering the magnifier to passing through the detector and being rejected, but with this embodiment, it only takes 3 cycles, which greatly reduces the area of the detector area. Guardrails are becoming unnecessary.

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 second enlarger and the annihilator are constructed from the same conductive pattern 6, and the detector 3 is placed within the hairpin loop of the conductive pattern 6. That's true. That is, the magnetic bubble is simultaneously expanded to the entire length of the first expander 21 by a current pulse flowing in a direction that reduces the vertical bias magnetic field in the center of the conductor pattern 6, and detected by the detector 3 at the same time. Immediately after the detection, a current pulse is applied to the conductive pattern 6 in the opposite direction to that at the time of expansion to cause it to disappear.

FIG. 4 shows the timing within the cycle of the functional units related to this series of operations. FIG. 4 shows the temporal relationship among the rotating magnetic field, detection output waveform, detection strobe pulse, and current pulse applied to the conductor pattern 6 in the second embodiment, and shows a, b, c, and d in this order, respectively.
is shown. According to this embodiment, the required transfer cycle from entering the enlarger to passing through the detector and being rejected is only 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 guardrails are no longer required in the detector region, making it possible to arrange many detectors at arbitrary positions within one element. It's summery. As a result, the degree of freedom in designing the layout of a large-capacity, high-performance magnetic bubble memory element increases, which 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, 23...first magnifier, 3...detector, 4...
. . . second enlarger, 5 . . . annihilator, 6 . . . conductor pattern.

Claims (1)

[Claims] 1. A magnetic bubble storage element comprising at least a magnetic bubble expander, a detector, and an extinguisher, wherein the expander includes a first expander made of a permalloin pattern and a first expander. a second expander made of a conductive pattern laid under the
The detector is a detector that detects the magnetic bubbles expanded by the first and second expanders, and the extinguisher is a detector that spreads the magnetic bubbles detected by the detectors under the permalloy pattern. A magnetic bubble memory element characterized in that it is an extinguisher that is extinguished by a conductive pattern. 2. The magnetic bubble memory element according to claim 1, wherein the second expander and the extinguisher are made of the same conductive pattern.