JPS634277B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an erasing circuit for erasing unnecessary bubbles.

In recent years, magnetic bubbles (hereinafter referred to as bubbles) that operate as storage media for magnetic bubble memory have been developed using a magnetic bubble with a diameter of 1 μm.
2. Description of the Related Art Memory devices with increased storage capacity using so-called submicron bubbles of less than m in size are being developed, and a method of transferring bubbles using a concatenated transfer circuit is being used.

In this method, a magnetic film that holds bubbles is formed by a first region having an axis of easy magnetization in a certain direction, and a second region surrounding this region and having an axis of easy magnetization orthogonal to this region. A major loop pattern for transfer and a number of minor loop patterns for storing bubble information are formed. It can be made by a method such as forming magnetic films with different directions.

Here we have the major loop pattern and the minor loop pattern.
Since the loop pattern has a shape in which a large number of disk-shaped patterns or rectangular patterns are connected, it is called a contiguous transfer circuit (contiguous disk pattern).

FIGS. 1 and 2 are explanatory diagrams of a connected transfer circuit, in which A is a front view and B is a sectional view taken along the line A-A'.

The magnetic film for bubble memory is made by liquid phase epitaxial growth of a magnetic garnet thin film 2, which serves as a bubble retention film, on a wafer 1 made of gadolinium gallium garnet (Gd ₃ Ga ₃ O ₁₂ , abbreviated as GGG), which is a non-magnetic garnet. After that, in the case of Figure 1, by implanting ions such as hydrogen ions (H ⁺ ), helium ions (He ⁺ ), and neon ions (Ne ⁺ ) into the parts other than transfer pattern 3, the axis of easy magnetization is aligned with the film surface. On the other hand, the direction of the axis of easy magnetization of the ion-implanted portion 4 of the magnetic garnet thin film 2 arranged in the vertical direction is tilted in the plane direction.

In the case of Fig. 2, a transfer pattern of garnet having an axis of easy magnetization in the plane, such as ytonium iron garnet (YIG), is formed on the magnetic garnet thin film 2, which is similar to ion implantation. If a bubble transfer circuit with such characteristics can be obtained, and the rotation direction of the driving magnetic field is clockwise, the bubbles 7 will be transferred in an articulated manner according to the rotation of the driving magnetic field, as shown in FIGS. 1A and 2A. Transfer is performed sequentially according to the circuit.

Bubble memory devices using such a concatenated transfer circuit include a single loop configuration and a major/minor loop configuration. There is a minor loop that does this.

Furthermore, functional gates such as bubble generators and erasers are made using conductive circuits.

Now, in such a bubble memory device, it is necessary to erase unnecessary bubbles after the writing or reading operation of bubble information has been completed, and conventionally, a method of erasing them using electric current has been used.

FIG. 3 is an explanatory diagram of a conventional erasing circuit that erases a bubble that transfers the readout major line after it is detected by a detector, and FIG. 4 shows the current waveform flowing therein.

Here, an example will be described in which a concatenated transfer circuit is manufactured using the ion implantation method.

In FIG. 3, a continuous transfer pattern 9 and a bubble stretch pattern 10 are surrounded by an ion implantation region 8 in which the axis of easy magnetization is oriented in the in-plane direction due to ion implantation, and are made up of a non-ion implantation region.
A conductor circuit 1 is formed on this by a vapor-deposited film made of aluminum/copper (Al/Cu) alloy or gold (Au).
1 is provided, and a magnetoresistive element 12 made of permalloy is provided on this conductor circuit with an insulating layer made of a silicon oxide (SiO ₂ ) deposited film interposed therebetween.

Here, to explain the detection and erasing functions in FIG. 3 when the driving magnetic field is rotating counterclockwise, the bubble 13 at the cusp position adjacent to the conductor circuit 11 in the connected transfer pattern 9 is 1
After rotation, it moves to the next cusp position 14. At this stage, when a pulse current 16 shown in FIG. The bubble expands inside the hairpin, and the presence of the bubble is detected by the magnetoresistive element 12.
Thereafter, the pulse current 17 shown in FIG. 4 is passed in the opposite direction to the stretching current, and the bias magnetic field applied to the bubble is increased to the value of the extinguishing magnetic field of the bubble, thereby performing erasure.

The above is a method for erasing bubbles on the read major line, but the unnecessary bubble information replaced by the swap circuit on the write major line is removed using the circuit shown in Figure 3, excluding the detector.
Erasing was performed by applying an erasing pulse.

In conventional bubble memory devices that use connected transfer circuits, bubbles are erased by applying pulsed current to the hairpin conductor circuit, but this method has drawbacks such as complicating the pulse power supply circuit. Ta.

The purpose of the present invention is to eliminate unnecessary bubbles in a device using a connected transfer circuit by guiding them to a guardrail, and as a method for this purpose, a merge circuit utilizing the magnetocrystalline anisotropy of magnetic garnet is used.

The merge circuit has been announced by TJ Nelson et al., and its operation is shown in FIG. 5 as follows.

(TJ Nelson et al, The Bell System
(Technical Journal. Vol. 59, No. 2, 1980) Garnet magnetic films for bubble memories have a uniaxial anisotropic magnetic field (Hk) perpendicular to the film surface and form an angle of 120° with each other in the plane direction. A weak magnetocrystalline anisotropy field (K ₁ ) exists.

Therefore, the connecting circuit formed on the film surface can be super track S, bad track b, or good track g depending on the direction of the magnetocrystalline anisotropy field (K ₁ ).
It can be divided into

Here, super track S has a large bias margin of the bubble transfer path and is a path where bubble transfer is easy, while bad track b has the narrowest bias margin and is a path where bubble transfer is difficult to occur. Track g is a path with an intermediate operating margin for bubble transfer.

Now, if the concatenated transfer circuit is formed as shown in FIG. 5, and the lower transfer circuit is patterned into a super track S, the upper transfer circuit will be a butt track B.

Now, in FIG. 5, it is assumed that a pattern of connected transfer circuits is formed with a left transfer circuit 18 and a right transfer circuit 19 spaced at a constant interval 20.

In this case, the bubbles 21 that have been transferred by the counterclockwise driving magnetic field below the left transfer circuit 18 are transferred next time, if the gap 20 is spaced within a certain value determined by the bubble diameter, the gap 20 is It works in the same way as the cusp in conventional bubble transfer, causing bubbles to stay there, and the next driving magnetic field causes them to be transferred to the transfer circuit 19 on the right side by the solid line arrow 2 in the figure.
The transfer is performed as shown in 2.

In addition, the bubble 23 transferred from the right side to the left side on the upper Bud track b by the right side transfer circuit 19 is transferred along with the transfer circuit by the driving magnetic field and reaches the gap 20, but the lower side transfer circuit Since it is a super track, it is not transferred to the left transfer circuit but is transferred to the lower transfer circuit as shown by the broken line arrow 24.

The merge function utilizes the magnetocrystalline anisotropy of magnetic garnet to transfer bubbles, and the present invention applies this to erasing bubbles by guiding unnecessary bubbles to the guardrail and erasing them using a merge circuit. It is.

Here, the guardrail has the same shape as the transfer pattern and is placed around the memory circuit in a bubble memory device and serves as a place to sweep out and eliminate unnecessary bubbles, and is used in conventional circuits using permalloy transfer circuits.

FIG. 6 is an explanatory diagram of a bubble erasing circuit using a merge circuit according to the present invention. There is a guardrail 26 around the chip 25, and a transfer circuit consisting of a major/minor loop is patterned in this. The positions of the read major line 27 and the write major line 28 are shown. 7th
The figure shows readout measure line 2 in this partially enlarged view.
7.Writing median line 28 and guardrail 2
It shows the relationship with 6.

In FIG. 7, the stripe-out easy axis is oriented in the direction shown in the center, and there is a read major line 27 and a write major line 28.
The lower side is the super track S, and the upper side is the butt track B. In addition, guardrail 26
Both transfer circuits on both sides are formed on the good track g.

Now, the unnecessary bubble 29 that has been transferred on the readout median line 27 is transferred to the gap 30 by the driving magnetic field rotating counterclockwise, but due to the merging function, it is transferred to the good track g of the guardrail 26, and from then on, it is transferred to the lower end of the guardrail 26. It goes around part 31 and exits to the outside part, and transfers the outside guardrail.

Next, the unnecessary bubbles on the write medium line 28 are similarly swept out to the outside of the guardrail 26 by the merge function without moving to the opposite side of the butt track b.

As described above, by using a merge circuit in a circuit from which unnecessary bubbles are to be erased, unnecessary bubbles can be guided to the guardrail and erased in the same manner as in the conventional circuit using a permalloy transfer pattern.

In a bubble memory device using a concatenated transfer circuit, the present invention uses a merge circuit to erase unnecessary bubbles by sweeping them out to a guardrail in the same way as in the past, whereas unnecessary bubbles are erased using current pulses. This makes it easier to delete unnecessary bubbles.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of a connected transfer circuit, where A is a front view, B is a sectional view taken along line A-A', Figure 3 is a conventional bubble detection/elimination device, and Figure 4 is a conventional bubble detection/elimination device. The pulse waveforms used, FIG. 5 is an explanatory diagram of the merging function, FIG. 6 is a diagram of the relationship between the guardrail and the measure line, and FIG. 7 is an explanatory diagram of the bubble erasing circuit according to the present invention. In the figure, 7, 13, 14, 21, 23, 2
9 and 32 are bubbles, S is super track, b is butt track, g is good track, 26 is guardrail, 27 is readout major line 28
is the writing median line, and 30 is the gap.

Claims (1)

[Claims] 1. A first region in which a magnetic film holding magnetic bubbles has an axis of easy magnetization in a certain direction, and surrounding the first region,
and a second region having an easy axis of magnetization substantially orthogonal to the easy axis of magnetization, and in which a magnetic bubble information transfer pattern is formed by the first region, the magnetic bubbles that are no longer needed are removed. An erasing circuit for a magnetic bubble memory characterized by using a merge circuit that utilizes magnetocrystalline anisotropy to lead to a guardrail and erase the memory.