A passive replicator comprising a plurality of elongated bars interposed between an input propagation path and a plurality of output propagation paths

George, Peter K.

Kobayashi, Tsutomu

NASA Technical Reports Server

United States Patent [19] 
George e t  al. 
[111 4,067,003 
P S I  Jan. 3, 1978 
[54] PASSIVE REPLICATOR 
[75] Inventors: 
[73] Assignee: 
[21] Appl. NO.: 
[22] Filed: 
Peter K. George, Placentia; Teutomu 
Kobayashi, Orange, both of Calif. 
Rockwell International Corporation, 
El Segundo, Calif. 
656,688 
Feb. 9,1976 
[51] Int. C l . 2  .............................................. CllC 11/14 
[52] U.S. Cl. ...................................................... 365/12 
[58] Field of Search .................................. 340/174 TF 
~561 References Cited 
U.S. PATENT DOCUMENTS 
3,868,661 2/1975 Bonyharo et al. ............ 340/174 TF 
3,876,995 4/1975 Clover et dl. ................. 340/174 'IF 
Primary Examiner-Vincent P. Canney 
Attorney, Agent, or Firm-L. Let! Humphries; H. 
Frederick Hamann; G. Donald Weber, Jr. 
P71 ABsTRAcr 
A passive replicator comprising a plurality of elongated 
bars interposed between an input propagation path and 
a plurality of output propagation paths. 
8 clrimr, 4 Dnwing Figures 
14A 
https://ntrs.nasa.gov/search.jsp?R=20080012261 2019-08-30T03:55:39+00:00Z
@ Jan. 3, 1978 4,067,003 
148 
A 
B 
FIG. I 
A 
B 
\ 
16 
FIG. 2 
!?A 14 A 
FIG. 3 --- FIG. 4 
4,067,003 
1 2 
PASSIVE REPLICATOR DESCRIPTION OF THE PREFERRED EMBODIMENT 
The invention described herein was made in the per- Referring now to FIG. 1, there is shown a basic em- 
formance of work under NASA Contract No. NAS 5 bodiment of the passive replicator of the instant inven- 
1-12981 and is subject to the provision of Section 305 of tion. In this representation, propagation path 14 is the 
the National Aeronautics and Space Act of 1958 (72 input path while chevron groups 10 and 11 represent 
Stat. 435; 42 U.S.C. 2457). the first columns of chevrons in output paths A and B, 
respectively. A plurality of elongated bars 12 are dis- 
10 posed between the elements of the respective propaga- BACKGROUND 
1. Field of the Invention 
This invention relates to magnetic bubble domain 
devices, in general, and to a passive replicator, in partic- 
ular. 
2. Description of Prior Art 
With the advent of magnetic bubble domain devices, 
a large amount of research and development has gone 
into designing and developing devices which can pro- 
vide various control functions relative to magnetic bub- 
bles in magnetic bubble domain material. These devices 20 
include propagation elements, switching devices, trans- 
fer gates and the like. One of the devices that has been 
developed is a replicator which permits bubbles propa- 
gating along a single input path to be supplied to a 
plurality of output paths. Several replicators are known 25 
in the art wherein the function thereof need not be 
discussed in detail herein. Moreover, many variations of 
replicators are known and include both passive and 
active replicators. However, these known replicators 
have associated problems and disadvantages. For exam- 30 
ple, active replicators require a control signal to be 
supplied thereto. This requires additional leads and 
structural geometry in the bubble domain system. Pas- 
sive replicators of the type known in the art have disad- 
vantages relative to throughput, high bias failures, the 35 
requirements of small spacings and high drive fields and 
the like. Improved devices with better operating char- 
acteristics are desirable in order to provide better sys- 
tem operation in the bubble domain field. 
SUMMARY OF THE INVENTION 
This invention relates to a passive replicator wherein 
a plurality of elongated bars are disposed intermediate 
an &input propagation path and a plurality of output 
propagation paths. The elongated bars cause the bubble 45 
domain propagating along the input path to be stretched 
and expanded to interact with the plurality of output 
paths. A cutter bar severs the expanded bubble into a 
plurality of distinct bubbles, e.g. the original bubble and 
a replica thereof which is propagated out via an exit 50 
path. Pusher bars or foreshortened bars may be dis- 
posed relative to the elongated bars to assist in the for- 
mation and control of bubbles therein. 
This replicator operates over a wide range of permal- 
loy to garnet spacing and requires a relatively low drive 55 
field for operation. 
15 
40 
BRIEF DESCRIPTION OF THE DRAWINGS 
FIG. 1 is a schematic representation of the basic em- 
bodiment of the invention. 60 
FIG. 2 is a schematic representation of another em- 
bodiment of the instant invention. 
FIG. 3 is another embodiment of the instant inven- 
tion. 
FIG. 4 is a schematic representation of another em- 65 
bodiment of the instant invention. 
In the several figures, similar components bear similar 
reference numerals. 
tion paths. In particular, the upper bar of bars 12 has one 
end thereof disposed between the end of propagation 
path 14 and the beginning of propagation path A. Thus, 
the bubble propagating along path 14 transfers from 
element 14A to the end 12D of uppermost bar 12 under 
the influence of the rotating field HR which is applied to 
bubble domain devices. Under the influence of the field 
HR, magnetic poles are creaed at the right-most end of 
each of the bars 12 wherein the bubble at 12D will 
rapidly expand along the right-most ends of the bars 12. 
By properly spacing bars 12 and using the appropriate 
number thereof, the bubble will expand substantially 
instantaneously across the right-most ends of all of the 
bars 12. Consequently, the bubble will extend adjacent 
the left ends of chevrons 10 and 11, respectively. 
As the rotating field continues to rotate, magnetic 
poles are formed at the left end of chevrons 10 and 11 as 
well as the left end of cutter bar 12A which is affied to 
one of the elongated bars 12. In particular, cutter bar 
12A is spatially interposed between chevron columns 10 
and 11. Because of these magnetic poles, bubbles are 
transferred to chevrons 10 and 11 and effectively split at 
cutter bar 12A. As field HR continues to rotate counter- 
clockwise, bubbles are transferred through chevrons 10 
and 11 to the right-most ends thereof as separate bub- 
bles. 
The device shown in FIG. 1 thus operates as a passive 
replicator, i.e. no control signals are required, and trans- 
fers a single bubble from propagation path 14 to output 
paths A and B as two separate bubbles. The device of 
the replicator uses elongated bars 12 as the stretching or 
expanding element. The elongated bars are extremely 
advantageous in that a deep potential well at the right 
end thereof exerts a considerable stripping effect even 
at high bias. Consequently, the bubble from path 14 will 
stretch more readily and more quickly wherein im- 
proved operation is achieved. 
In one investigation of the replicator shown in FI 
1, it has been shown that for a 16 pm period device with 
a garnet-to-permalloy spacing of 0.58pm, a margin of 
12-14 Oe at 50 Oe is obtained. This operational charac- 
teristic is considerably better than prior art devices. 
Referring now to FIG. 2, there is shown another 
embodiment of the instant invention. In FIG. 2, compo- 
nents which are similar to those shown in FIG. 1 bear 
similar reference numerals. However, an additional 
plurality of bars 15 are provided. Bars 15 are substan- 
tially parallel and coextensive with bars 12. However, 
bars 15 (two of which are shown although any suitable 
number can be utilized) are positioned beyond the end 
of the column of chevrons 11. Bars 15 may be utilized in 
some areas to control the operation of the bubble trans- 
ferred from propagation path 14. For example, in cer- 
tain low bias field situations, the bottom bubble section 
which is split off at cutter bar 12A may expand and strip 
out along the bottom-most elongated bars 12. In this 
situation, these bubbles may continue to propagate 
along the bottom-most bars 12 and eventually be driven 
4,o 
3 
therefrom. In order to prevent this situation, bars 15 
provide, essentially, repelling bars which repel the bub- 
ble back toward chevrons 11. That is, repelling bars 15 
provide poles (and barriers) which prevent the bubbles 
from stripping-out from chevrons 11 to bars 12 when 
the rotating field produces magnetic poles at the left end 
of bars 12. 
Referring now to FIG. 3, there is shown a schematic 
representation of another embodiment of the instant 
invention. Again, the components in FIG. 3 which bear 
reference numerals similar to those in previous figures 
are similar components. In the embodiment shown in 
FIG. 3, an additional repeller or pusher bar 16 is pro- 
vided. The pusher bar is arranged substantially perpen- 
dicular to the propagation paths to provide a magnetic 
pole between the ends of bars 12 and chevrons 11 in 
propagation path B. In particular, as the rotational field 
HR rotates in the counter-clockwise direction, a mag- 
netic pole is produced at the right ends of chevrons 12 
and 15 to which a bubble would tend to expand. Subse- 
quently, a magnetic pole is produced at the upper end of 
repeller bar 16 which tends to push the bubble back up 
the pattern of bars 15. Again, subsequently, a magnetic 
pole is generated at the left ends of chevrons 11 to trans- 
fer the bubble from chevrons 12 to chevrons 11. 
It should be understood, of course, that in the em- 
bodiment shown in FIG. 3, bars 15 may be omitted and 
additional bars parallel (or substantially parallel) to 
repeller bar 16 may be included. These repeller bars 
generally retard the strip out of the bubble along the 
bottom of bars 12 under low bias. 
Referring now to FIG. 4, there is shown a schematic 
representation of another embodiment in the instant 
invention. Again, components which are similar to 
those shown in previous embodiments bear similar ref- 
erence numerals. However, in FIG. 4 certain of elon- 
gated bars 12 have been foreshortened. In particular, 
bars 12B and 12C are shown as shorter than the remain- 
der of the stretcher bars. While two bars are shown 
shortened, it is conceivable that one or more bars may 
be shortened in accordance with the specific pattern to 
be determined to be the most advantageous for any 
given system. Typically, however, the shortened bars 
are disposed adjacent to cutter bar 12A. Again, elon- 
gated bars 15 or repeller bar 16 may be included or 
omitted as desired. The shortened bars 12B and 12C will 
reduce, in certain situations, the possibility of produc- 
tion of stray bubbles caused by cutting of bubbles by the 
bars adjacent to the cutter element 12A. While this 
potential problem could possibly be eliminated by mov- 
ing the chevron tracks closer together, the approach of 
shortening bars 12B and 12C is desirable whereby the 
propagation tracks can be maintained widely separated 
to avoid any interaction therebetween. 
Thus, there have been shown and described preferred 
embodiments of a passive replicator. In particular, there 
is shown a plurality of elongated bars interposed be- 
tween input and output propagation paths. The elon- 
gated bars are disposed at an angle relative to the propa- 
gation paths. The output paths are shown as chevrons 
having a specific angle with the propagation paths. The 
elongated bars are depicted as having a steeper angle 
than the chevron elements. A number of bars is shown 
and suggested along with a number of propagation 
paths and elements therein. Any number of bars or 
elements can be utilized as a function of the specific 
operations required and the operating parameters in- 
volved. 
867,003 
4 
It is recognized that those skilled in the art may con- 
ceive modifications to the invention. For example, it is 
possible that more output paths may be utilized or a 
larger number of elongated bars may be incorporated 
5 wherein the output paths may be mote widely spaced 
apart. However, any modifications which fall within 
the purview of the instant description are intended to be 
included herein. 
Having thus described a preferred embodiment of the 
1. A passive replicator device comprising 
first propagation path means for propagating infor- 
mation therealong in a first direction, 
second and third propagation path means for propa- 
said second and third propagation paths disposed 
adjacent to said first propagation path in order to 
receive information from said first propagation 
path such that information is propagated in said 
fust, second and third propagation paths substan- 
tially in said first direction, 
said second and third propagation paths having ends 
thereof substantially adjacent to each other and in 
substantially parallel arrangement, 
said first propagation path having an end thereof 
adjacent to said ends of said second and third prop- 
agation paths and substantially in abutment there- 
with, 
a plurality of elongated bars in substantially parallel 
arrangement, 
said plurality of elongated bars disposed adjacent to 
said ends of said first, second and third propagation 
paths, 
an end of at least one of said elongated bars intcr- 
posed between said end of said first propagation 
path and the end of at least one of said second and 
third propagation paths whereby said plurality of 
elongated bars will receive information propagat- 
ing along said first propagation path and expand 
said information to substantially encompass said 
ends of said second and third propagation paths, 
each of said plurality of elongated bars having length 
substantially greater than the length of said ends of 
said first, second and third propagation paths, and 
a cutter bar associated with said elongated bars, 
said cutter bar including an elongated bar having a 
relatively shorter bar portion disposed at an angle 
to said elongated bar and projecting between said 
ends of said second and third propagation paths. 
2. The combination recited in claim 1 wherein said 
plurality of elongated bars extends beyond the end por- 
tions of said second and third propagation paths in a 
direction substantially normal to the direction of propa- 
3. The combination recited in claim 1 including at 
least one repeller bar arranged substantially normal to 
the direction of propagation adjacent the ends of said 
plurality of magnetic bars and said third propagation 
4. The combination recited in claim 1 wherein at least 
one of said elongated bars is arranged to be shorter than 
the remainder of said elongated bars. 
5. Magnetic apparatus comprising 
a layer of material in which single wall domains can 
be moved, 
a multistage pattern of devices coupled to said layer 
and operative responsive to'a magnetic field reori- 
10 invention, what is claimed is: 
l5 gating information therealong, 
2o 
25 
3o 
35 
40 
45 
50 
55 gation through said paths. 
60 path. 
65 
5 
4,067,003 
6 
enting in the plane of said layer to move domains 
from stage to stage along a path, 
said pattern defining in a reference stage a linear 
array of elongated elements forming attracting 
poles for enlarging said domains laterally with 
respect to said path, 
said reference stage including an additional element 
arrangement, ing 
said additional element arrangement connected to 10 
and angularly disposed with respect to one of said 
elongated elements of said reference stage in a 
manner to generate an intermediate repelling pole 
for cutting domains moved from said reference 
stage to a next subsequent stage. 
6. A passive replicator comprising 
a first propagation path, 
a plurality of substantially linear elongated magnetiz- 
able elements disposed adjacent to said first propa- 
receive and expand a magnetic bubble domain 
therefrom, 
second and third propagation paths adjacent to said 
plurality of elements to receive portions of an ex- 25 
panded bubble therefrom, and * * + * *  
a relatively short element angularly connected to at 
least one of said elongated elements and interposed 
between said second and third propagation paths to 
selectively provide a magnetic pole which severs 
an expanded bubble domain into at least two sepa- 
rate domains which are received by said second 
and third propagation paths, respectively. 
7. The passive replicator recited in claim 6 compris- 
a further plurality of elongated Magnetizable ele- 
ments disposed parallel to the first mentioned plu- 
rality of elongated magnetizable elements, 
at least one repeller bar arranged substantially normal 
to said first propagation path and adjacent the ends 
of said further plurality of elongated magnetizable 
elements, and 
at least one relatively short magnetizable element 
disposed adjacent to the elongated element having 
said short element connected thereto. 
8. The passive replicator recited in claim 6 wherein 
5 
15 
20 
gation path and at an therewith in Order to said second and third propagation paths are formed of 
chevron elements, and 
said elongated magnetizable elements are arranged 
approximately normal to the near side of said chev- 
rons. 
30 
35 
40 
45 
50 
55 
60 
65 


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