Note: Descriptions are shown in the official language in which they were submitted.
~(~53796
This application is a divisional of Canadian Application Number 215,070,
filed December 2, 1974, and assigned to the same applicant.
Cross Reference to Related Patents
U.S. Patent No. 3,913,079 issued October 14, 1975 and commonly assigned
herewith, describes a pump propagation structure for moving interactive ele-
ments, and in particular for moving magnetic bubble domains. Bubble domains
confined to move in a certain direction are moved
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1 in that direction by localized magnetic fields which expand
2 bubble domains, thereby forcing other bubble domains to
3 move in the preferred direction.
4 Background of the Invention
Field of the Invention
6 This invention relates to techniques for improving
7 the access time in systems using arrays of interactive
8 elements, and in particular for improving the access time
9 of magnetic bubble domains in a system using a confined array
(lattice) of such bubble domains.
11 Description of the Prior Art
12 The concept of using a lattice of interactive
13 elements in information handling systems was first presented
14 in U.K. Patent 1,454,451 granted March 2/77 and commonly assigned herewith. In that application, an embodiment showed a large array of
16 magnetic bubble domains confined within a rhombus shape.
17 These bubble domains interact with one another and have
18 positions within the rhombus which are substantially deter-
19 mined by those interactions. In that system, access to
bubble domains within the lattice array took place by serially
21 removing a column of bubbles from one of the ends of the
22 lattice. Once the first column of bubble domains has been
23 removed, the second column is then serially removed.
24 In the lattice arrangements described hereinabove,
the access time to a random bi,t of information in the lattice
26 is approximately equal to (1/2) NBT, where NB is the total
27 number of bubble domains in the confined rhombus and T is
28 the basic cycle time of the system. The basic cycle time
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1 is the time required to ~ove a bubble domain several
2 bubble diameters. For large systems, NB may be 108
3 and T may be 1 microsecond. In that situation, the
4 access time for a random bit would be 50 seconds.
The access time can be improved by decreasing
6 the block size (lattice size) and increasing the number
7 of blocks per magnetic chip. However, this approach
8 leads -to a large number of connections to the magnetic
9 chip. '
Accordingly, it is a primary object of the
11 present invention to provide a technique for extracting
12 information from a lattice of interactive elements with
13 minimum access time.
14 It i9 another object of the present invention
to provide a technique for accessing interactive elements
16 within a lattice of such elements by means which provide
17 only a minimum number of interconnections.
18 It is a further object of this invention to
19 provide a technique for readily accessing information
from a lattice of interactive elements wherein the
21 information sta~e can be replaced within the lattice.
22 It is still another object of this invention
23 to provide a system utilizing a lattice of interactive
24 elements including structure for moving elements within
the lattice and for removing elements from the lattice
26 in a direction substantially transverse to the direction
27 of movement of elements within the lattice.
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1 It is a further object of this invention to
2 provide techniques for reducing information access time
3 in systems using lattices of magnetic bubble domains.
4 Brief Summary of the Invention
The column access technique proposed herein does
6 not serially move information from one end of a lattice to
7 the other for extracting the interactive elements. Instead,
8 the interactive elements are removed from the lattice in a
9 direction substantially transverse to the direction defined
by the prior art lattice systems where information is put
11 in at one end of the lattice and removed at the other end
12 of the lattice. Consequently, elements can be removed from
13 interior positions of the lattice, rather than having to be
14 removed from positions at the ends of the lattice.
Means are provided for translating the lattice and
16 for extracting interactive elements from the lattice in a
17 direction substantially transverse to the direction of
18 translation of elements within the lattice. Additionally,
19 means are provided to return the extracted information into
the same positions within the lattice, or for regenerating
21 the removed information. In particular, the bubble pump
22 shift register described in aforementioned U.S. Patent No.
23 3,913,079 can be utilized for removal of a column of
24 interactive elements from the lattice. After detection of
the removed elements, new elements having the same informatlon
26 state can be inserted into the lattice, or the same elements
27 can be returned to the lattice.
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1 Although the use of many types of interactive elements
can be foreseen, a particularly good example is provided using magnetic
bubble domains. Thus, the following description will be concerned
with magnetic bubble domains, although other variations can be utilized.
For instance, styrofoam elements (as shown in ~I.K. Patent ~o. 1,454,451)
having magnetic elements embedded therein can float on a suitable medium,
such as water. These elements will interact with one another in the
same manner as magnetic bubble domains and can therefore be moved on
the water surface by the column accessing structure of the present
invention. If the styrofoam balls are color coded, information storage
and displays are readily provided.
These and other objects, features, and advantages will
be more apparent from the following more particular description of the
preferred embodiments.
Brief Description of the Drawings
FIG. 1 is a conceptual drawing illustrating the
principle of column accessing.
FIG. 2 is a detailed diagram of an overall system
configuration for implementing column accessing of elements within a
lattice.
FIG. 3 is a diagram of a portion of FIG. 1, illustrating
the input/output of bubble domains to/from a lattice, and appears on
same page as FIG. 1.
FIG. 4 is a diagram of a portion of the structure of
FIG. 2, showing the structure used for nucleation, expansion, splitting,
annihilation, and propagation of domains within a bubble domain pump
used for column accessing.
FIG. 5 is an illustration of a portion of the structure
of FIG. 2, showing in particular the apparatus used to read information
taken from the lattice.
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1 FIG. 6 illustrates a portion of the structure of FIG. 2,
showing in particular the propagation of bubble domains within the
lattice, and appear on same page as FIG. 2.
FIG. 7 illustrates a portion of the structure of FIG~ 2,
showing in particular the generation and annihilation of domains at
the buffer zones of the lattice.
FIG. ~ is a circuit diagram showing a bubble domain
lattice using column accessing in which information removed from the
lattice is returned to the same locations within the lattice by the
bubble domain pump.
Detailed Description of the Preferred Embodiments
FIG. 1 is a conceptual illustration showing how column
accessing works. A lattice L of interactive elements 10, such as
magnetic bubble domains, is held within a confinement means 12. This
confinement means is any type of structure which provides a magnetic
barrier to the bubble domains 10. For instance, such confinement means
can be comprised of permalloy strips, ion implanted regions, and etched
grooves in the bubble domain material. All of these structures are
described in more detail in aforementioned United Kingdom Patent
No. 1,454,451.
Buffer regions are located on the left and right-hand
ends of the lattice L and are used for translation of the lattice to
the left or to the right. Oonductor lines
~053796
1 can be used to move stripe domains and bubble domains in
2 the buffer regions to implement bubble domain translation
3 to the left or to the right.
4 Vertically displaced arrows 14 are used to
indicate the direction of movement of columns of bubble
6 domains 10. That i8, a plurality of write stations 16
7 is provided at the top of lattice L and a plurality of
8 read stations 18 i5 provided at the bottom of lattice L,
9 in order to define a plurality of input/output ports.
Bubble domains 10 are moved in the direction of the arrows
11 to the read stations 18 ana then destroyed or returned to
12 the same locations within lattice L, after the read
13 operation.
14 In FIG. 1, it i5 noted that normal lattice trans-
lation is in a horizontal direction from left to right, or
16 the reverse. However, elements are removed from the
17 lattice in a direction substantially transverse to this.
18 Also, elements can be removed from interior positions or
19 end positions of the lattice. This is in distinction with
the lattice arrangement of aforementioned United Kingdom Patent 1,454,451,
21 where columns of~ bubble domains are entered into the lattice
22 along the left-hand end and removed from the lattice at
23 the right-hand end of the lattice.
24 Provision of a plurality of write stations 16
and read stations 18, together with means for propagating
26 the bubble domains along the paths indicated by the arrows,
27 produces column accessing. As the number of input-output
28 ports is increased, the amount of lattice translation
29 (along the horizontal direction) is decreased at the
YO973-044 -7-
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' :
1 expense of the number of chip connections. A reasonable
2 design for a system might comprise 10~ magnetic bubble
3 domains, and 8 input-output ports. This would lead to a
4 ratio of storage area/(storage area I buffer area) = 8/9.
For a cycle time of 1 microsecond, the access time to any
6 random bubble domain would be 10 milliseconds.
7 FIG. 2
8 FIG. 2 shows a detailed diagram of structure
9 required ~o implement column accessing of bubble domains
within a lattice array. Individual portions of this
11 circuit will be shown in more detail in ~ubsequent
12 FIGS. 3-7.
13 In more detail, a lattice array L of magnetic
14 bubble domains 10 is confined within the confinement -
means 12. Confinement means 12 is a barrier to the
16 escape of bubble domains 10 and serves to keep these
17 domains within a confined area. As is apparent, the
18 confinement barrier is also used for the columns (input/
19 output) which extend transversely to the lattice.
At the left-hand end of the confinement means 12
21 is an input means generally designated 20. The input
22 means is compri~ed of a bubble domain generator 22 which
23 provides bubble domains for insertion into lattice L, a
24 shift register SRl which moves the domains from the
generator 22 to positions where they can be inserted
26 into lattice L, and a series of conductors A, B, C
27 through which currents can be passed for creation of
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.
1(~5~796
1 magnetic fields which insert the bubble domains into the
2 lattice. This type of conductor input means is more fully
3 described in aforementioned United Kingdom Patent No. 1,45~,451.
An output means, generally designated 24, is
6 comprised of conductors A', B' and C'. These conductors
7 have analogous functions to the conductors A, B and C
8 in that currents through these conductors provide magnetic
9 fields for pulling domains from the lattice L. This type
of output means is also well described in United Kingdom
11 Patent No. 1,45~,~51.
12 After removal of a column of bubble domains 10
13 from the lattice, shift register means can be provided
14 in the normal fashion for moving the domains to other
par~s of the magnetic medium in which they exist. In
16 this drawing, shift register SR2 is located between
17 conductors B' and C' and can be, for instance, comprised
18 of conductor loop patterns for moving domains in
19 conventionally well known ways.
If desired, a bubble pump shift register of the
21 type described in aforementioned United States Patent No.
22 3,913,079 can be used to provide bubble domains
23 at the input of the lattice and for removing bubble domains
24 at the output of the lattice.
In the description to follow, the input means 20
26 and output means 24 are utilized to provide the initial
27 lattice. After an initial lattice is produced within the
28 confinement means 12, the input and output means are no
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1 longer needed if other bubble domain generators are utilized,
2 or if bubbles removed from the lattice are returned to the
3 lattice.
4 A bias field source 26 provides a magnetic bias
S field Hz substantially normal to the plane of the lattice L.
6 Source 26 can be any of a number of well known sources,
7 including permanent magnets, magnetic layers exchange
8 coupled to the magnetic medium in which the bubble domains
9 exist, and current carrying conductors. For instance, it
may be desirable to have a different value of bias field
11 within lattice L than outs1de the lattice. Accordingly,
12 the bias field source will provide a proper bias field
13 over different regions of the magnetic sheet if that is
14 desired. Of course, if a bubble pump propagation means
is used for input and output of bubble domains from the
16 lattice, a uniform field Hz can be used throughout the
17 magnetic medium. Techniques for doing this are within the
18 skill of the art and are also described in aforementioned
19 U.K. Patent No. 1,454.451.
A source 28 provides an in-plane magnetic field H
21 which can be used for various functions. For instance,
22 such a field may be used for movement of magnetic domains
23 in shift registers SRl and SR2 located outside the lattice
24 area.
Buffer zones 28L and 28R are located at the
26 left-hand end of the lattice and at the right-hand end of
27 the lattice, respectively. These buffer zones are comprised
28 of stripe domains 30 and means 32L and 32R for generation
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1 and annihilation of these stripe domains. For instance,
2 32~ is comprised of conductors 34A and 34B which are
3 connected to buffer current sources 36A and 36B, respectively.
4 On the right-hand end of the lattice, means 32R is comprised
of conductors 38A and 38B, connected to buffer current
6 sources 40A and 40B, respectively.
7 The operation of the generation and annihilation
8 means 32L- and 32R Will be explained in re detail later.
9 At this time it is appropriate to say that these structures
14 are used to generate and annihilate stripe domains in the
11 buffer zones 28L and 28R. This generation and annihilation
12 of stripe domains is used to translate the lattice L to the
13 left or to the right.
14 In FIG. 2, two write stations W-A and W-B are
provided at the top of the lattice. At the bottom edge
16 of the lattice, two read stations R-A and R-B are
17 provided. In general, the write stations are used to
18 produce magnetic domains which in turn are used to push
19 bubble domains out of the lattice into the associated
read stations. In the embodiment of FIG. 2, two columns
21 of bubble domains 10 can be pushed out of the lattice
22 into the associated read stations for detection of the
23 information carried by the bubble domains. It should be
24 noted that the generalized translation direction of the
25 lattice is from left to right or right to left, while the
26 removal of a column of bubble domains from the lattice is
27 essentially transverse to thi~ horizontal left +~ right
2 8 direction.
YO973-044 ~11-
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l Each write station is comprised of a bubble
2 domain generator and a pusher for serially pushing domains
3 into a bubble domain pump. In FIG. 2, two pumps P-A and
4 P-~ are provided for moving bubble domains in two columns
out of the lattice L. Pump P-A is comprised of current
6 carrying conductors 42L and 42R. These conductors are
7 connected to pump current sources 44L and 44R, respectively.
8 - Pump propagation means P-B is comprised of
9 conductors 46L and 46R. These are connected to pump
current sources 48L and 48R, respectively.
ll The operation of the pump propagation means P-A
12 and P-B is explained in detail in aforementioned United
13 States Paten~ No. 3,913.079. Essentially, currents
14 in a pair of pump conductors cause expansion of domains
15 between the conductors. This expansion causes other domains
16 to move with the net result that propagation of domains occurs
17 in the column defined by the pump conductors. This will be
18 explained in more detail with respect to FIG. 3.
19 AS mentioned, each write means is comprised of
20 a domain generator and a pusher for serially pushing domains
21 into the column defined by the adjacent pump conductors.
22 For instance, write means W-A is comprised of a bubble domain
23 generator 50A and a bubble domain pusher 52A. Pusher 52A iS
24 comprised of conductors 54L and 54R, which are connected to
25 a pusher current source 56A. Generator 50A is comprised of
26 a three-legged conductor structure in which the two outer
27 legs 58 and 60 are connected to a current source 62A while
28 metal conductor 64 iS connected to ground.
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1 Write means W-B is comprised of bubble domain
2 generator and annihilator 50B and serial bubble domain
3 pusher 52B. Generator 50B is comprised of conductors
4 which are connected to current source 62B while pusher 52B
is comprised of current carrying conductors connected to
6 pusher current source 56B. Since generator 50B is the
7 same as generator 50A and since pusher 52B is the same as
8 pusher 52A, the details of write means W-B will not be
9 further explained. Accordingly, the individual conductors
of these components are not given reference numerals.
11 The operation of the write means W-A will be
12 explained in more detail with respect to FIG. 4.
13 Accordingly, at this point in the discussion, it is
14 only necessary to state that the generator 50A can be
use~ to nucleate and annihilate domains, as well as to
16 split them. If properly designed, this generator will
17 provide coded bubble domains for information storage.
18 The pusher 52A will push domains in serial fashion into
19 the column defined by the associated pump propagation
means P-A.
21 Two read means R-A and R-B are provided for
22 use with the associated write means W-A and W-B,
23 respectively. Because the structure of means R-A is
24 identical to that of R-B, only read means R-A will be
described in detail.
26 Read means R-A is generally comprised of a
27 bubble domain serial puller 66A, a bubble domain serial
28 pusher 68A, and a bubble domain sensor 70A. Puller 66A
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is comprised of conductors 72L and 72R, which are connected
2 to puller current source 74A. Serial pusher 68Ais comprised
3 of conductors 76L and 76R which are connected to a pusher
4 current source 78A. Serial puller 66A moves bubble domains
in serial fashion (one at a time) from the column of the
6 associated bubble pump P-A. Serial pusher 68Ais used to
7 push bubble domains, one at a time, toward the direction of
8 the Y-shaped confinement means 80A. Aswill be more clearly
9 understood later, pusher 68Ais also used to create a
gradient magnetic field in the Y-shaped region defined by
11 the boundaries 80A. This in turn is used to deflect the
12 bubble domains in accordance with their wall magnetization
13 structure. Accordingly, the domains can be detected for
14 their information content by this technique.
Sensing means 70AiS illustrated as comprising
16 a conductor 82A connected to a sensing element 84A, which
17 can conveniently be a magnetoresistive sensing element of
18 the type well known in the art. A sensor current source 85A
19 produces electrical current through sensor ~lement 84A. In
20 FIG. 2, an elongated bubble domain 86iS adjacent to the
21 sensor 84A.-
22 A conductor loop 88AiS adjacent to the left-hand
23 leg of the Y-shaped propagation channel while a conductor
24 loop 90A is adjacent to the right-hand portion of the
25 Y-shaped propagation path. Conductor loop 88Ais connected
26 to current source 92A while conductor loop 90Ais connected
27 to current source 94A. Conductor loops 88A and 90A are
28 used for expansion and collapse of domains in the respective
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1 portions of the Y-shaped propagation channel. That is,
2 current in loop 90A will expand the domain 86 to provide
3 a maximum signal to be sensed by detector 84A. Later this
4 same conductor loop can be used to collapse the domain 86.
The operation of the read means R-A will be described in
6 more detail with respect to FIG. 5.
7 Since read means R-B is identical to read means R-A,
8 it will not be explained in detail. Corresponding portions
9 of read means R-B have the same reference numerals as those
of means R-A, except that the suffix B is used.
11 A control means 95 synchronizes the operation of
12 the various components used in the system of FIG. 2.
13 Control 9S provides input trigger pulses to the pump current
14 sources 44, pusher current sources 56, 78, puller current
sources 74, input/output conductors A-C, A'-C', buffer
16 current sources 36, 40, sensor current sources 85, in-plane
17 field source 28, bias field source 26, annihilate/generate
18 current sourçes 62, and current sources 92 and 94.
19 The pump propagation structure is a shift register
that can be used for access ~input/output) of bubble domains
21 to and from the lattice L. Additionally, it is a one-dimensional
22 lattice itself, since the bubble domains confined in it havé
23 positions largely determined by mutual interactions between
24 the bubble domains. Conse~uently, the structure of FIG. 2
is comprised of two lattices (confined arrays) of magnetic
26 bubble domains, where one lattice is two-dimensional while
27 the other lattice is one-dimensional. Also, the first and
28 second lattices include bubble domains which are common to
YO973-044 -15-
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1 each lattice, and the second lattice can be thought of as
2 intersecting the first lattice.
3 Initialization of the Lattice
4 In the embodiment of FIG. 2, an input means 20
is provided for bringing bubble domains to the left-hand
6 end of the lattice L. These domains can then be inserted
7 into the lattice by the associated conductors. The force
8 required to move the bubble domains into the lattice area
9 is that which overcomes the repulsive force of bubble
domains within the lattice. If there are no bubble domains
11 within the lattice, the bubble domains which enter the
12 lattice will spread out in order to minimize the energy
13 of the lattice. These domains merely have to overcome the
14 repulsive force of the barrier 12 in order to enter the
lattice area. Consequently, bubble domains can be continually
16 loaded into the lattice area until a number is reached which
17 will provide a regular lattice having a given lattice spacing
18 aO between bubble domains. For instance, m columns having
19 n elements in a column may be placed in the lattice. After
this, the lattice can be slightly perturbed by further input
21 elements in order to remove any dislocations or vacancies
22 from the initially formed lattice. That is, after the
23 lattice is initially formed, additional columns of bubble
24 domains are entered into the lattice and a corresponding
number removed from the lattice by the output means 24.
26 This provides a filtering action and insures that all
27 dislocations and vacancies will have translated through
28 the entire lattice area to the output end where they are
YO973-044 -16-
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1 removed. This filtering operation may take one or more
2 cycle~ in which the lattice is totally recycled.
3 An alternate technique for achieving an initial
4 lattice o magnetic bubble domains is to first apply a
large in-plane magnetic field (using source 28) to
6 saturate the magnetic medium. After this, the in-plane
7 magnetic field is released to obtain a dense, random
8 array of bubble domains. The lattice is then magnetically
9 annealed b~ a time-modulated magnetic field (produced by
source 26) normal to the bubble domain material, in order
11 to obtain a regular lattice.
12 Still another technique for providing an initial
13 lattice is one which generates bubble domains at selected
14 locations in a magnetic medium. For instance, a permanent
magnet having a pattern of apertures in it ~not shown) can
16 be brought into close proximity to the magnetic medium,
17 after the medium has been heated to a temperature above
18 its Curie temperature Tc. This will cause nucleation of
19 bubble domains in the magnetic sheet at locations corresponding
to the pattern in the permanent magnet.
21 ~nother technique for providing an initial lattice
22 of bubble domains utilizes stripe domains which can be cut.
23 A pattern of stripe domains is produced by a magnetic field
24 in the plane of the magnetic sheet, in a well known manner.
These stripe domains are then cut to provide rows of bubble
26 domains. The cutting device is any device which produces a
27 magnetic field of sufficient amplitude in a direction
28 substantially normal to the magnetic medium. As an example,
Y0973-04~ -17-
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l a recording head can be moved across the stripe domain pattern
2 in sequential fashion to cut the stripes, thereby producing
3 rows of bubble domains. Another alternative would be to use
4 a plurality of conductors arranged transversely to the
direction of the stripe domains. Pulsing these conductors
6 will produce magnetic fields which will cut the stripe domains,
7 thereby leading to the rows of bubble domains.
8 Steps for producing an initial lattice are known in
9 the art and are described in some detail in aforementioned
U.K. Patent No. 1,454,451.
ll Operation of the Structure of FIG. 2
12 The following will be a generalized description
13 of the functions which are performed in the structure of
14 FIG. 2. The detailed operations of the various components
of this structure will be explained with reference to the
16 subsequent figures which show the various components.
17 Generation and annihilation of stripe domains 30
18 in the buffer zones 28L and 28R are used to move the lattice
l9 to the left or to the right. For instance, the lattice L
will be shifted to the right when stripe domains are
21 generated i~ buffer zone 28L and annihilated in buffer
22 zone 28R. A reverse operation will shift the lattice to
23 the left. This type of operation will maintain the same
24 number of bubble domains in the lattice during translation.
The lattice translation operation continues until
26 the desired column of bubble domains is situated in the
27 region between the appropriate bubble pump conductors.
28 That is, the bubble domain column to be taken from the
29 lattice must be in a proper input/output port.
YO973~044 -18-
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1 ~ubble domains in a selected column are then
2 moved out of the lattice by pulsing the appropriate
3 pump conductors. During this operation, the appropriate
4 bubble domain generator will produce bubble domains which
are serially entered into the lattice to maintain the
6 proper spacing of elements within the lattice. The generator
7 can also provide coded bubble domains in order to replenish
8 the exact information taken from the lattice.
9 At the read end of the bubble domain pump, bubble
domains are sensed and the sense signals can be sent to
11 associated circuitry, such as a computer.
12 As will be seen by reference to FIG. 8, techniques
13 can be utilized to return the original bubble domains to
14 their positions within the lattice after being removed from
the lattice and read by a sensing station.
16 Additionally, it should be noted that the bubble
17 domains need not be coded within the lattice, if the lattice
18 is used for other types of applications. However, if the
19 bubble domains are coded, any type of coding can be utilized.
In the discussion to follow, the coding technique described
21 in United States Patent No. 3,~90,605 issued June 17, 1975
22 will be assumed as the type of coding used. Other types
23 of coding may utilize the hard-soft properties of magnetic
24 bubble domains (United States Patent No. 3,~99,799 issued August 12,
25 1975), right and left-handedness of unichiral magnetic bubble domains
26 (United Kingdom Patent No. 1,454,451 granted March 2, 1977), dual size
27 magnetic bubble domains (U.S. Patent No. 3,911,411 issued September 30,
28 1975), etc. All of these aforementioned patents are commonly assigned
29 herewith.
YO973-044 -19-
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1 Description of the Various ComPonents
2 FIG. 3 shows the structure used to provide
3 input~output of bubble domains to/from a column in the
4 lattice. The lattice L is comprised of bubble domains 10
and a column therein is defined b~ the pump conductors
6 42L and 42R. Although only a portion of these conductors
7 as well as portions of other conductors are showm in
8 this drawing, the amount of detail presented is sufficient
9 to enable one to understand the operation of this component.
The serial puller 66A is also shown. This puller
11 includes conductors 72L and 72R which form a U-shaped loop
12 that i9 grounded at its mid-point.
13 In operation, bubble domains within the area
14 defined by conductors 42L and 42R will be expanded when
currents flow in these conductors. Expanded domains 10-1,
16 10-2, 10-3, 10-4, and 10-5 are shown in this drawing.
17 Expansion of these domains exerts forces on other domains
18 in the column, causing movement of the domains in a
19 downward direction. ~owever, the bubble domain puller 66A
insures that bubble domains entering the lower portion 96
21 of the column propagation path defined by barrier 12 enter
22 it one at a time. As will be seen later, this provides
23 control over the reading station in order to be able to
24 detect each separate domain.
When the current in the pump conductors is removed,
26 the expanded domains 10-1 ... 10-5 shrink and other domains
27 from the associated write means W-A enter the areas that
28 the expanded domains have vacated. Thus, there is a
YO973-044 -20-
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1 continual downward push of bubble domains in the column
2 defined by the pump conductors 42L and 42R.
3 Because the pump propagation means is symmetrical,
4 bubble domains can be pushed upwardly in the column if such
is desired. However, operation of the structure of FIG. 2
6 moves bubble domains downwardly to the read station for
7 detection thereat.
8 In the input/output operation of the column
9 accessing structure, the associated generator 50A will provide
a single bubble domain each time one is required for movement
11 into the column. The associated pusher 52A will cause serial
12 movement of these bubble domains into the bubble pump structure.
13 Accordingly, use of the serial pushers and pullers insures
14 that a fixed amount of bubbles is always present in the
column and that synchronization of the column accessing
16 will occur. In this manner, the control unit 95 can keep
17 track of the domains which are read from the lattice area.
18 Th~ bubble domain pump structure can be used to
19 provide a regular lattice. In this case, an array of
bubble domains is produced within confinement means 12
21 through the use of a large in-plane magnetic field (several
22 thousand Oe) which is then reduced to zero. This produces
23 an array of bubble domains within confinement means 12.
24 By modulating a perpendicular bias field Hz, the array will
move into a lattice configuration. At this time, the
26 bubble domain pump structure can be used to insure that a
27 proper number of bubble domains is present in each column.
YO973-044 -21-
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1 As an example, assume that an array of 100 by 100
2 bubbles is required. This means that there will be 100
3 columns, each of which has 100 bubble domains therein. The
4 bubble domain pump conductors are used to line up a bubble
domain column between the conductors. At this time, a high
6 current in the pump conductors will force all of the bubble
7 domains between the conductors to move together to create a
8 single~strip domain between the conductors. If the current
9 in the pump conductors is then reduced, this strip domain
will get smaller and become a single bubble domain. The
11 generator and pusher associated with the pump conductors
12 is then activated to produce 99 domains. Since only one
13 domain was present in the column located between the pump
14 conductors, insertion of 99 domains in serial fashion will
provide a column having exactly 100 domains therein.
16 Accordingly, the associated serial pusher on
17 one end of the pump propagation means and the associated
18 serial puller on the other end of the propagation means
19 can be used to define the length of the bubble domain
column. Each end of the bubble domain pump can be opened
21 (to allow Pubble domains to pass) or closed (to restrict
22 movement of bubble domains).
23 After a 100-bubble domain column has been formed,
24 this column can be shifted in the lattice by using the
buffer zones as described previously. At this time, another
26 column of bubble domains (which may or may not have the
27 proper amount of domains) is moved into the area between
28 the pump conductors and is treated as described previously.
YO973-044 -22-
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1 This continues until 100 columns having 100 bubble domains
2 in each column are produced.
3 FIG. 4
4 FIG. 4 is a diagram of the bubble domain generator 50A
and bubble domain serial pusher 52A. Generator 50A can perform
6 the functions of nucleation, expansion, splitting, annihilation,
7 and propagation. Pusher 52A is used to move bubble domains
8 one at-a time to the lattice, as indicated in FIG. 4.
9 The constraining border for the bubble domain pump
is indicated by the solid line 12. This confining means can
11 be, for instance, ion implanted regions of the magnetic
12 bubble domain material grooves, etc. which create a barrier
13 to restrain the bubble domains 10 within this barrier.
14 Generator 50A is comprised of a three-legged
current carrying conductor structure, with the two outer
16 conductors being 58 and 60 while the inner conductor is 64.
17 Outer conductors 58 and 60 are connected to a current source 62A
18 which is not shown in this drawing.
19 Serial pusher 52A iS comprised of a U-shaped
20 conductor having portions 54L and 54R which are tied to
21 ground at their midpoint. Conductors 54L and 54R are
22 connected to pusher current source 56A (not shown in this
23 figure).
24 Generator 50A can be used to nucleate bubble
25 domains in the following way. For typical rare earth iron
26 garnet bubble domain materials, a current of 300-400 milliamps
27 in either conductor 58 or conductor 60 will create a
28 localized magnetic field adjacent to the conductor which
YO973-044 -23-
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1 will nucleate a domain. At this time, the bias field Hz
2 normal to the bubble domain medium can be appro~imately zero
3 or set at the bias for operation of the lattice.
4 Once the initial domain is nucleated, generator
50A merely splits off bubble domains from it for propagation
6 to the lattice. The splitting operation is accomplished
7 by putting currents into conductors 58 and 60. This causes
8 the initial domain 100 to expand as shown in the drawing.
9 During this stretching operation, magnetic fields are
established which pinch the bubble 100 at its center,
11 causing it to split. The currents used for this operation
12 are about 100 milliamps.
13 The split domain is then attracted by pusher 52A
14 by putting a current through conductor 54L. Current through
conductor 54R holds bubble domains on the right-hand side
16 of this conductor during this operation. The currents
17 utilized have amplitudes of approximately 10 milliamps.
18 The bubble domains 10 are then pushed in serial fashion to
19 the lattice. By pulsing the pump conductors, the bubble
domains in the lattice will be expelled as described with
21 reference ~o FIG. 3.
22 FIG. 5
23 FIG. 5 shows the read means R-A used to detect
24 domàins from the lattice which have been coded in terms
of their wall magnetization rotation. This type of coding
26 is described in more detail in aforementioned U.S. Patent No.
27 3,390,605 is5ued June 17, 1975. Briefly, magnetic bubbles can
28 be made to deflect through different angles in a gradient
YO973-044 -24-
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1 magnetic field normal to the magnetic medium depending
2 upon the number of rotations of their wall magnetization.
3 Thus, the propagation channel in FIG. 5 branches into a
4 Y in order to allow bubble domains to deflect into either
S one of the legs of the propagation channel. Sensors
6 then detect the bubble domains and an indication is
7 obtained of the information contained within the lattice.
8 In more detail, FIG. 5 shows the serial bubble
9 domain pusher 68A which is comprised of conductors 76L
and 76R which are tied to a common ground. Conductors 76L
11 and 76R are connected to pusher current source 78A, which
12 is not shown in this drawing.
13 The sensing means 70A is comprised of a sensing
14 element 84A which is connected to a current carrying
conductor B2A. In a preferred embodiment, sensor 84A
16 could be a magnetoresistive sensor which i5 operated in
17 a manner well known in the prior art (U.S. 3,691,540).
18 Current sources 78A, 85A, 92A and 94A are not shown in
19 this figure.
In operation, bubble domains 10 are pushed out
21 of the lattice by the bubble pump means and move downwardly
22 to the serial pusher 68A. This pusher allows one bubble
23 domain at a time to cross the Y-shaped region of the
24 propagation path, in order to determine the deflection
25 properties of the bubble domains. Current through
26 conductor 76R provides a magnetic field gradient in the
27 direction of the Y-shaped grooves and individual domains
28 move downwardly under the influence of this gradient field.
YO973- 044 -25-
~05~7~6
1 Depending upon the deflection properties of a domain,
2 it moves either to the left-hand path 102 or to the
3 right-hand path 104. At this time, current is put into
4 conductor loop 90A which causes the domain 86 to be
expanded. This expanded domain is detected by sensor 84A
6 and a signal can be fed to external circuitry, such as a
7 computer. After being sensed, current through conductor
8 loop 90A is reversed to collapse the domain 86.
9 A sensor is not needed to detect bubble domains
moving in path 102. Since the domains were coded in a
11 prescribed way initially, any domain which moves into
12 path 102 can be detected by noting the absence of a
13 signal produced by element 84A at that time. If a
14 domain moved into path 102, it would be collapsed by a
magnetic field due to current in conductor loop 88A.
16 For the reading technique of FIG. S, bubble
17 domains must be able to freely float in a gradient
18 magnetic field produced by pusher 68A. Therefore, domains
19 in paths 102 and 104 which have been sensed are collapsed
before the serial pusher 68A sends another domain through
21 the gradient field. This insures that the domains deflect
22 properly in the gradient magnetic field, rather than
23 undergoing deflection due to the influence of other domains.
24 FIG. 6
FIG. 6 illustrates propagation of magnetic
26 bubble domains 10 within the lattice L. As stated previously,
27 domains 10 propagate in a horizontal direction either to
28 the left or to the right depending upon the generation and
Yo973-044 -26-
lOS:~7gl6
1 annihilation of stripe domains in the buffer regions 28L
2 and 28R. This translation of motion of the lattice is
3 used to place a column of bubble domains between the pump
4 conductors 42L and 42R.
For proper placement of the bubble domains
6 between the pump conductors, currents can be put in
7 individual pump conductors in order to move a column of
8 bubbles into the region between the two conductors. Thus,
9 it is possible to fine-tune the tion of the desired
column of lattice bubbles which are to be removed from
11 the lattice.
12 FIG. 7
13 FIG. 7 shows a portion of the buffer zone 28L
14 including the barrier 12 and the generate/annihilate
conductors 34A and 34B. These conductors are connected
16 to buffer current sources 36A and 36B respectively, which
17 are not shown in this drawing.
18 At this time it should be remembered that the
19 function of the buffer zones is to translate the bubble
domain lattice to the left or to the right. This is done
21 by the controlled generation and annihilation of stripe
22 domains in the buffer zones on either side of the lattice.
23 Initially, the entire area surrounded by the
24 confinement barrier 12 contained a perfect lattice. At
this time, current is put into conductors 34A and 34Bo
26 These currents will create magnetic fields which will
27 squeeze the bubble domains located between conductors 34A
28 and 34B. The bubble domains thus squeezed will merge into
YO973-044 -27-
~05~7~6
1 a stripe domain 30 which will remain between conductors 34A
2 and 34B.
3 At the same time the cvnductors 38A and 38B in
4 buffer zone 28R are energized in tha opposite direction in
S order to collapse the row of bubble domains which is
6 located between them. Consequently, the entire lattice is
7 now arranged such that it can be shifted to the right by
8 one column width. To do so, current is passed through
9 conductor-34B in a direction which attracts the stripe domain
between conductors 34A and 34B to the right-hand side of
11 conductor 34B. During this operation, a current in the
12 proper direction in the left-hand conductor 34A may be used
13 to aid movement of the stripe domain to the right.
14 Additional stripe domains may be created between
conductors 34A and 34B by applying currents of approximately
16 400-500 milliamps in these conductors. The localized
17 magnetic field produced between the conductors will nucleate
18 domains between these conductors. If the currents through
19 the conductors are reduced, these domains will expand to the
length of the lattice in order to form a new stripe domain.
21 Conti~nued nucleation of stripe domains in the
22 left-hand buffer zone and collapse of bubble domain rows
23 in the right-hand buffer zone will produce a number of
24 stripe domains 30 in the left-hand buffer zone. At this
time, the lattice is shifted to the left and one-half of
26 the stripe domains created in the left-hand buffer zone are
27 collapsed by applying large currents to the conductors 34A
28 and 34B. This creates a large ma~netic field for annihilation
Y0973-044 -~8-
~05379~
1 of domains between these conductors. At the same time, new
2 stripe domains are being generated on the right-hand side
3 of the lattice.
4 - This operation continues until approximately
one-half of the stripe domains initially produced in the
6 left-hand buffer zone have been collapsed and a corresponding
7 number of stripe domains have been formed in the right-hand
8 buffer zone. Thus, an arrangement is obtained having equal
9 amounts of stripe domains in both the left-hand buffer zone
and the right-hand buffer zone.
11 The number of stripe domains required in the
12 buffer zones depends on the size of the lattice and on the
13 number of input/output ports. That is, there must be a
14 sufficient number of stripe domains to be able to move all
bubble domains within the lattice to a column for accessing.
16 Generally, for a lattice containing 100 columns of 100
17 bubbles, with 1 input/output column at the center of the
18 lattice, about 50 stripe domains will be required in each
19 buffer zone. However, if there are two input/output
column accessing ports spaced 1/3 and 2/3 of the distance
21 from th~ ends of the lattice~ then 34 stripe domains will
22 be required in each buffer zone.
23 The stripe domains have approximately the
24 same width and spacing as the bubble domains within the
lattice. Therefore, it can be readily calculated how
26 many stripe domains are needed for a lattice of a given
27 size in a given area, with a given amount of input and
28 output column acces~ing ports. The fundamental principle
YO973-044 -29-
105~796
1 is that the buffer zones should have sufficient numbers
2 of stripe domains to insure that all bubble domains will
3 be able to be translated to a column for accessing from
4 the lattice. During this translation operation, the
total number of stripe domains in both buffer zones
6 remains constant.
7 FIG. 8
8 FIG. 8 illustrates a lattice system in which
9 column accessing is used to remove bubble domains from
the lattice. However, this system differs from that
11 shown in FIG. 2 in that the bubble domains removed from
12 the lattice are returned to the lattice after being sensed.
13 Whenever possible, the same reference numerals
14 will be used for the embodiment of FIG. 8 as were used for
the other embodiments. Therefore, a lattice L comprised
16 of magnetic bubble domains 10 is present within the
17 confinement means 12. The confinement means also defines
-18 a closed loop propagation path generally designated 106.
19 This propagation path is used to ve magnetic bubble
domains around the lattice for re-entry therein after being
21 sensed. Additionally, propagation pump conductors 42L
22 and 42R are provided for moving bubble domains into and
23 out of the lattice L. The bubble domain pusher 52 is
24 provided as well as a bubble domain generator/splitter/
collapser 50.
26 On the other side of the lattice, a bubble
27 domain puller 66 is provided as well as a bubble domain
28 serial pusher 68. Bubble domain pusher 52 and bubble
YO973-044 -30-
~053796
1 domain puller 66 can be selectively opened and closed
2 to allow the bubble domains to move into and out of the
3 lattice L.
4 A bubble domain sensor 70 i8 provided and in
addition, bubble domain puller/pushers 108A and 108B
6 are also provided. Pushers 108A and 108B are used to
7 move magnetic bubble domain-~ which have been deflected
8 by a gradient field produced by pusher 68. Accordingly,
9 they move magnetic bubble domains in the two propagation
paths 102 and 104 into the closed loop 106 so that other
11 bubble domains can be detected.
12 In operation, the entire loop 106 can be
13 filled with magnetic bubble domains. This means that
14 application of current to the pump conductors 42L and
42R will expand domains in the lattice, thereby causing
16 domains to be moved to the pusher 68. This pusher allows
17 one domain at a time to move in the gradient magnetic
18 field. AccQrdingly, a domain in that field will move
19 either into path 102 or path 104 depending upon its
wall magnetization state. Sensor 70 is then used to
21 detect the aomains after which they are moved further
22 along their respective paths by either pusher 108A or
23 pusher 108B. These pushers are synchronized so that the
24 relative order of the bubble domains is retained as they
proceed toward closed loop 106. That is, by alternately
26 pulsing pushers 108A and 108B, the same order for magnetic
27 bubble domain movement will be provided.
28 By repeatedly pulsing conductors 42L and 42R,
29 domains within the lattice L will be sent to the read
YO973-044 ~31-
105;~796
1 station, detected, and then returned to their proper
2 places back in the lattice.
3 If the loop 106 is not initially loaded with
4 magnetic bubble domains, generator 50 can be used to
provide domains for pushing other domains out of the
6 lattice and around the loop 106. For instance, it may
7 be desired to push twenty-five bubble domains at a time
8 out of the column of the lattice to be accessed. To do
9 this, pusher 52 is closed (that is, current in this pusher
prevents bubble domains in the lattice ~rom moving
11 upwardly past pusher 52) and puller 66 is opened (that is,
12 no current flows in puller 66 so that bubble domains can
13 exit from the lattice in a direction toward this puller).
14 At this time, puller 66 is closed and pusher 52
is opened. A nucleated domain produced by generator 50 is
16 then split and placed in the column where domains have
17 left. Twenty-five new domains are produced by generator 50
18 which are pushed by pusher 52 into the column, thereby
19 replacing the twenty-five domains which have been removed
from the lattice.
21, .Pusher 52 is then closed and puller 66 is opened
22 in order to repeat the operation for another twenty-~ive
23 domains. This continues until all domains within the
24 lattice column to be accessed have been removed from the
lattice and detected. The bubble pump conductors are
26 then utilized to move domains around closed loop 106 until
27 the original domains within the lattice are returned to
28 the same positions within the lattice.
YO973-044 -32-
105;~796
1 Synchronization of the various functions performed
2 by the different components in the structure of FIG. 8 can
3 be accomplished by an external control means such as that
4 described with respect to FIG. 2. Such circuitry is well
known in the electronics art and utilizes clocking and
6 timing pulses for triggering current sources used to activate
7 the various components.
8 In the operation of column accessing in accordance
9 with the present invention, bubble domain spacing within
the lattice is established in a manner which allows a
11 column of bubble domains to be removed from the lattice.
12 That is, enough lattice flexibility exists such that a
13 desired column of bubble domains can be moved by the
14 bubble pump conductors into and out of the lattice. For
instance, a lattice constant (center-to-center domain
16 spacing) of approximately 2 bubble diameters can be
17 utilized, in a typical lattice system.
18 What has been described is an improved technique
19 for accessing interactive elements contained within a
lattice of such interactive elements. These interactive
21 elements can be any type of elements which tend to repel
22 one another. A particularly useful example is comprised
23 of a lattice of magnetic bubble domains. The present
24 accessing technique can remove columns of the interactive
elements from the interior of the lattice, rather than
26 having to translate the column to be accessed to one end
27 of the lattice. That is, the interactive elements are
28 removed from the lattice in a direction substantially
YO973-044 -33-
~OS3796
1 transverse to the usual translation direction of elements
2 within the lattice.
3 The interactive elements within the lattice can
4 be moved in the lattice by conventional means or by using
end buffer zones for shifting the lattice in two directions.
6 Whatever the means for moving the lattice, a column of
7 bubble domains in the lattice can be quickly accessed,
8 detected, and returned to the lattice. As an alternative,
9 the detected elements can be annihilated and the information
rewritten into the lattice by other qimilarly coded inter-
11 active elements.
12
Y0973-044 -34-
.. ~ .
