WO1982001959A1 - Memoire a bulles magnetiques - Google Patents

Memoire a bulles magnetiques Download PDF

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Publication number
WO1982001959A1
WO1982001959A1 PCT/US1981/001496 US8101496W WO8201959A1 WO 1982001959 A1 WO1982001959 A1 WO 1982001959A1 US 8101496 W US8101496 W US 8101496W WO 8201959 A1 WO8201959 A1 WO 8201959A1
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WO
WIPO (PCT)
Prior art keywords
elements
bubble
memory
field
accordance
Prior art date
Application number
PCT/US1981/001496
Other languages
English (en)
Inventor
Electric Co Western
Herbert M Shapiro
Andrew H Bobeck
Original Assignee
Electric Co Western
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US06/209,900 external-priority patent/US4357682A/en
Priority claimed from US06/209,901 external-priority patent/US4355373A/en
Application filed by Electric Co Western filed Critical Electric Co Western
Publication of WO1982001959A1 publication Critical patent/WO1982001959A1/fr

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C19/00—Digital stores in which the information is moved stepwise, e.g. shift registers
    • G11C19/02—Digital stores in which the information is moved stepwise, e.g. shift registers using magnetic elements
    • G11C19/08—Digital stores in which the information is moved stepwise, e.g. shift registers using magnetic elements using thin films in plane structure
    • G11C19/0808—Digital stores in which the information is moved stepwise, e.g. shift registers using magnetic elements using thin films in plane structure using magnetic domain propagation
    • G11C19/0816—Digital stores in which the information is moved stepwise, e.g. shift registers using magnetic elements using thin films in plane structure using magnetic domain propagation using a rotating or alternating coplanar magnetic field

Definitions

  • This invention relates to magnetic bubble memories and more particularly to such memories in which bubbles move along a path of magnetically soft elements responsive to a reorienting in-plane magnetic field.
  • Magnetic bubble memories are well known in the art. Bubble propagation is accomplished in such memories by creating a changing pattern of localized magnetic field gradients.
  • U. S. Patent Mo. 3,534,347 of A. H. Eobeck issued October 13, 1970 discloses a "field-access" mode bubble memory in which the localized field gradients are produced in a pattern of magnetically soft elements adjacent the bubble layer by a magnetic field rotating in the plane of bubble movement.
  • the elements typically of Permalloy, have a geometry and orientation such that the rotating in-plane field produces in them in consecutively offset positions magnetic poles which attract bubbles and which are operative to move bubbles along a path defined by the elements.
  • T-bar geometry disclosed in the abovementioned patent, was one of the original circuit patterns used. That pattern employs elements oriented at 90 degrees to one another so that each 90 degree rotation of the inplane field moves the bubble to a new position. Efforts to improve the operating margins of bubble memories have resulted in a number of known alternative geometries, including the Y-bar, the asymmetric half-disc, and the presently used asymmetric chevron.
  • the propagation path is formed by a series of the elements oriented in such a manner that due to the rotation of the in-plane field and consequent pole formation, a bubble moves to successive positions on an element, and at a certain point, again due to the geometry of the pole formation, transfers to the next adjacent element.
  • the bubble lingers near the end of the instant element until it sees a stronger attractive pole on the next adjacent element and then transfers to that element. It is thought to be advantageous for the pole formed on the element to which the bubble transfers to be strong enough to "pull" the bubble over to complete the transfer. This requirement limits the element design of the propagation circuit.
  • the present invention is directed at a fieldaccess bubble memory having relatively attractive operating margins.
  • a new mechanism for propagation as well as a new geometry for 'the propagation elements allows for more efficient transfer of a bubble from one element to the next, makes more efficient use of space for pole formation, and permits higher packing densities to be achieved.
  • a propagation element comprises two segments of different lengths oriented at an angle one to another thus forming a long bar section and a shorter end in what may be visualized as a chevron shaped element with a short downstream leg.
  • the elements are oriented diagonally with respect to the direction of the bubble path with the short leg of one element leading directly to the long leg of the next adjacent down stream element.
  • the elements are made of a magnetically soft material, typically Permalloy, responsive to the rotation of an inplane magnetic field. As the in-plane field rotates, poles form which make the short end act as a bubble "trap".
  • the bubble waits in the trap and is prevented by the shapes of the elements from backwards propagation until the in-plane field switches the magnetization of the long bar section of the elements and the bubble is ejected directly to the next element.
  • a bubble finds itself in a magnetic field originating at an upstream portion of the instant element and terminating at the other side of a gap on the next subsequent downstream element, the magnetic field providing a strong propagating force for moving the bubble.
  • the diagonal orientation of the elements with respect to the direction of propagation allows a relatively large element to be formed within a square area of unit size allotted to a single period of the memory thus achieving relatively strong poles.
  • FIG. 1 is a block diagram of a magnetic bubble memory
  • FIGS. 2 (comprising subfigures 2A, 2B, 2C, 2D, 2E), 3, and 4 are enlarged top views of portions of the memory of the type shown in FIG. 1 showing propagation elements of different embodiments of this invention;
  • FIG. 5 is a margin plot of a memory test circuit of the type shown in FIG. 3;
  • FIG. 6 is a view similar to that of FIG. 4 but showing a different embodiment of the invention. Detailed Description
  • FIG. 1 shows a magnetic bubble memory 10 including a host layer 11 of a material in which magnetic bubbles can be moved. Bubbles are moved in layer 11 in paths, l 1 , l 2 ...and l k which are commonly referred to as minor loops, and in addition, in a path of ML commonly referred to as a major loop. Storage of data is provided by the minor loops.
  • the major loop provides for access to the minor loops of substitute data from a bubble generator 12 and for read out of addressed data at a detector 13.
  • generator 12 comprises an electrical conductor connected between a generate pulse source 14 and ground operative under the control of control circuit 15 to provide a pulse selectively during each cycle of a propagation drive circuit represented by block 17.
  • Detector 13 similarly is shown connected between a utilization circuit 18 and ground and may include a magnetoresistance detector element. Bubbles are maintained at a nominal diameter by a bias field supplied by source 19.
  • a transfer-in conductor 20 couples those ends of the minor loops with associated stages of the major loop for transferring new data into the minor loops at the proper time.
  • Conductor 20, to this end, is connected between a transfer-in pulse source 21 and ground as shown.
  • a similar transfer operation termed a transferout operation, occurs at the top ends of the minor loops as viewed.
  • the transfer-out operation is controlled by a pulse in conductor 25 which is similarly connected between pulse source 26 and ground.
  • the control of the transfer functions as well as the generator, propagation and detector operations is derived from a master clock in accordance with well understood principles. Such circuitry along with an address register is considered to be included within control circuit 15.
  • the general organization of the memory of FIG. 1 thus can be seen to involve the generation of a bubble pattern at 12 for later storage in the minor loops by the activation of transfer-in conductor 20 during a write operation. Also involved is the transfer-out of addressed data from the minor loops by the activation of transfer-out conductor 25.
  • the data transferred out advances to detector 13 for applying signals representative of the transferred bubble pattern to utilization circuit 18.
  • the data move counterclockwise along loop ML until a later transfer-in operation moves the data back into vacancies at the bottom of the minor loops as viewed.
  • FIG. 2 shows a portion of a propagation path of FIG. 1 employing shortened chevron or L-shaped elements.
  • the succession of figures of FIG. 2 is intended to show a representative portion of an illustrative path with poles formed due to a rotating in-plane field, and the positions occupied by a bubble propagating along this path.
  • the in-plane field rotates clockwise and propagation is to the right.
  • FIG. 2A shows a bubble at an assumed initial position on element 30 where the attractive poles accumulate for the direction in which the in-plane field H D points.
  • a positive pole is created at the top of the element and the bubble moves to occupy the position shown in FIG. 2B.
  • Further rotation of the field by 90 degrees leaves the bubble in the same position while, the strong negative pole reorients to the position shown in FIG. 2C.
  • the in-plane field rotates another 90 degrees, to the orientation shown in FIG. 2D, the bubble moves into the position shown in that figure. This position, at the short end of element 30, constitutes a bubble "trap".
  • the bubble is prevented from backwards propagation by the presence of negative poles, as shown, and waits in the trap until the rotating in-plane field begins to switch the magnetization of the long bar segment of element 30 to that shown in FIG. 2E.
  • positive and negative poles are present in the adjacent elements 30 and 31 at such positions, as shown, to create a magnetic field the axis of which extends directly along the desired path for movement of the bubble between the elements.
  • the bubble thus passes from element 30 directly to an awaiting attractive pole formed in element 31.
  • the bubble advances one period in one cycle of the drive field.
  • FIG. 3 shows an alternative geometry for the propagation elements of FIGS. 2A to 2E which is a variation of the basic L-shape shown in those figures.
  • Elements 50, 51, 52 and 53 of FIG. 3 have the above-mentioned "pickaxe” or "T" shape and are separated by gaps 60, 61 and 62.
  • Propagation of a bubble along these elements is analogous to propagation along the propagation pattern of FIGS. 2A- 2E.
  • the bubble moves from position P 1 to P 2 to P 3 to P 4 .
  • FIG. 4 shows an illustrative minor loop I 3 composed of Permalloy elements of still another shape which are operative with relatively wide gaps.
  • the figure also shows transfer-in and transfer-out conductors 20 and 25 for moving bubbles between the major loop ML and the minor loops. Bubble movement is counterclockwise in the minor loops, turns 100 and 101 being defined for such operation.
  • a transfer operation is carried out in response to a pulse applied to conductor 20 or 25 by source 21 or 26 respectively.
  • a bubble moving from left to right along the lower horizontal leg of path ML passes position 110 from whence normal rotation of the in-plane field causes the bubble to move to position 111.
  • FIGS. 2A- 2E, 3 and 4 The significance of the embodiments of FIGS. 2A- 2E, 3 and 4 lies in the fact that adjacent elements are separated by gaps which, as previously noted, can be significantly wider than prior art gaps. It has been accepted in the bubble art that a gap between adjacent elements of a propagation path for bubbles is necessarily small compared to a bubble diameter at the collapse field. It has also been established that a period or distance through which a bubble is moved during a single cycle of the in-plane drive field is large, typically four to five times a bubble diameter at the strip-out field.
  • the gap separating adjacent elements of a bubble path can (at best) be 1.0 ⁇ , thus requiring (heretofore) a somewhat larger bubble, e.g., of 1.7 ⁇ diameter, hence a period of 8.0 ⁇ .
  • the present invention allows a change to be made in the relationship between the gap width and the bubble diameter.
  • 4.0 ⁇ period circuits can be realized with 1.0 ⁇ gaps and 0.8 ⁇ bubbles.
  • the present invention permits four million bit memories on a like-size chip (approximately 8 millimeters on a side) with the same photolithography techniques.
  • Bubble memories with patterns tolerant of wide gaps as disclosed herein are characterized by relatively low drive fields.
  • FIG. 5 shows margin data for elements of the type shown in FIG. 4. The data was taken for a square array of elements of the type shown in FIG. 4 having top (.), left (x), bottom (o), and right (+) legs. The legend in the figure corresponds to these designations. The vertical axis represents bias field and the horizontal axis represents drive field. It can be seen that low drive fields and wide margins are achieved.
  • This margin data is representative of data taken on a significant number of samples.
  • the particular data was taken with bubble tests circuits having 6000 Angstrom units (Angstrom) of S 1 O 2 and 2000 Angstrom of Permalloy.
  • the thicknesses of both the S 1 O 2 and Permalloy layers have been varied with similar results.
  • the transfer function described in connection with FIG. 4, utilizes conductive strips 20 and 25 overlying the bubble layer 11 which are current pulsed to alter the path of the bubble being transferred. Such transfers, however, can also be accomplished without such strips, as now described in connection with FIG. 6.
  • bubble movement is caused by a magnetic field reorienting, usually by rotating, in the plane of bubble movement.
  • a f i eld is provided by the propagate field source 17.
  • Transfer of bubbles both in and out of the minor loops is accomplished in the FIG. 6 arrangement by a properly phased reversal of that field's direction of rotation.
  • a transfer control circuit is utilized in this arrangement in place of the transfer in pulse source 21 shown in FIG. 1, such control circuit being adapted to alter the direction of the field rotation under the control of control circuit 32.
  • Control circuit 32 is adapted to synchronize and control all functions herein and is assumed to include a clock, counters, and address generators for this purpose as is now well understood in the art.
  • FIG. 6 shows an enlarged top view of a minor loop (viz. l 3 ) about which bubbles recirculate counterclockwise as indicated by curved arrows 140 and 141 in the figure.
  • the normal clockwise rotation of the drive field moves bubbles through the sequence of positions P 1 , P 2 , and P 3 .
  • control circuit 32 signals the transfer control circuit to reverse the direction of rotation of the drive field.
  • a bubble occupying position P 2 of elements 145 at the time of the reversal moves to position P T at element 146. All remaining (untransferred) bubbles are now in positions P 1 .

Landscapes

  • Thin Magnetic Films (AREA)

Abstract

Une nouvelle geometrie pour les elements de propagation d'une memoire a bulles magnetiques a acces de champ tolere des espaces relativement larges entre les elements et des champs d'entrainement inferieurs, d'ou il resulte une plus grande densite de stockage de donnees d'information et un fonctionnement a energie reduite. Les elements (30, 31) ont des formes qui definissent des "pieges" de bulles fonctionnant pour retenir les bulles dans le but d'obtenir des transferts d'une efficacite relativement elevee entre les elements. Dans d'autres modes de realisation, les elements (50-53) ont une forme en L ou en "pioche".
PCT/US1981/001496 1980-11-24 1981-11-09 Memoire a bulles magnetiques WO1982001959A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US209900801124 1980-11-24
US06/209,900 US4357682A (en) 1980-11-24 1980-11-24 Conductorless transfer for magnetic bubble memories
US06/209,901 US4355373A (en) 1980-11-24 1980-11-24 Magnetic bubble memory
US209901 1988-06-22

Publications (1)

Publication Number Publication Date
WO1982001959A1 true WO1982001959A1 (fr) 1982-06-10

Family

ID=26904626

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1981/001496 WO1982001959A1 (fr) 1980-11-24 1981-11-09 Memoire a bulles magnetiques

Country Status (3)

Country Link
EP (1) EP0067170A4 (fr)
JP (1) JPS57501803A (fr)
WO (1) WO1982001959A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0099750A2 (fr) * 1982-07-19 1984-02-01 Fujitsu Limited Dispositif de mémoire à bulles magnétiques
EP0101187A2 (fr) * 1982-07-17 1984-02-22 Fujitsu Limited Dispositif de mémoire à bulles magnétique
EP0155212A2 (fr) * 1984-03-03 1985-09-18 Fujitsu Limited Dispositif de mémoire à bulles magnétiques

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3613058A (en) * 1969-11-20 1971-10-12 Bell Telephone Labor Inc Magnetic domain propagation arrangement
US3815107A (en) * 1971-06-30 1974-06-04 Ibm Cylindrical magnetic domain display system
US4086661A (en) * 1974-03-14 1978-04-25 Fujitsu Limited Cylindrical magnetic domain element
USRE29677E (en) * 1971-11-09 1978-06-20 Bell Telephone Laboratories, Incorporated Single-wall domain arrangement
US4157591A (en) * 1976-08-10 1979-06-05 U.S. Philips Corporation Magnetic domain device
SU706879A1 (ru) * 1978-07-31 1979-12-30 Предприятие П/Я А-1631 Канал продвижени цилиндрических магнитных доменов
JPS5587377A (en) * 1978-12-22 1980-07-02 Nec Corp Magnetic bubble element

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4034357A (en) * 1975-08-15 1977-07-05 International Business Machines Corporation Patterns for use in the field access propagation of a bubble lattice

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3613058A (en) * 1969-11-20 1971-10-12 Bell Telephone Labor Inc Magnetic domain propagation arrangement
US3815107A (en) * 1971-06-30 1974-06-04 Ibm Cylindrical magnetic domain display system
USRE29677E (en) * 1971-11-09 1978-06-20 Bell Telephone Laboratories, Incorporated Single-wall domain arrangement
US4086661A (en) * 1974-03-14 1978-04-25 Fujitsu Limited Cylindrical magnetic domain element
US4157591A (en) * 1976-08-10 1979-06-05 U.S. Philips Corporation Magnetic domain device
SU706879A1 (ru) * 1978-07-31 1979-12-30 Предприятие П/Я А-1631 Канал продвижени цилиндрических магнитных доменов
JPS5587377A (en) * 1978-12-22 1980-07-02 Nec Corp Magnetic bubble element

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0067170A4 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0101187A2 (fr) * 1982-07-17 1984-02-22 Fujitsu Limited Dispositif de mémoire à bulles magnétique
EP0101187A3 (en) * 1982-07-17 1986-03-19 Fujitsu Limited Magnetic-bubble memory device
EP0099750A2 (fr) * 1982-07-19 1984-02-01 Fujitsu Limited Dispositif de mémoire à bulles magnétiques
EP0099750B1 (fr) * 1982-07-19 1989-01-04 Fujitsu Limited Dispositif de mémoire à bulles magnétiques
EP0155212A2 (fr) * 1984-03-03 1985-09-18 Fujitsu Limited Dispositif de mémoire à bulles magnétiques
EP0155212A3 (fr) * 1984-03-03 1989-03-15 Fujitsu Limited Dispositif de mémoire à bulles magnétiques

Also Published As

Publication number Publication date
JPS57501803A (fr) 1982-10-07
EP0067170A4 (fr) 1985-07-01
EP0067170A1 (fr) 1982-12-22

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