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Патент USA US3030530

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April 17, 1962
H. D. CRANE
3,030,519
"AND" FUNCTION CIRCUIT
Filed Jan. 20, 1958
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1
United States Patent 0 "me
3,030,519
Patented Apr. 17, 1962
1
current is pulsed through the central opening in the core
10, as by a clearing winding 16, the flux in the core may
3,030,519
“AND” FUNCTION CIRCUIT
be saturated in a clockwise direction. The core is then
Hewitt D. Crane, Palo Alto, Calif., assignor to Burroughs
Corporation, Detroit, Mich, a corporation of Michigan
said to be in a cleared or binary zero condition.
If a
large current is passed through either of the apertures 12
Filed Jan. 20, 1958, Ser. No. 710,148
7 Claims. (Cl. 307-88)
or 14, as by either of the windings 18 and 20, in the direc-v
tion indicated in FIG. 2, and the current is of sufficient
This invention relates to circuits for performing a logi
magnitude to cause switching of flux around the central
cal “and” function, and more particularly, is concerned
opening of the annular core, a portion of the flux can be
with an “and” function circuit employing magnetic core 10 reversed so that the ?ux extends in opposite directions on
elements.
either side of the respective apertures 12 and 14, as in
In copending application, Serial No. 698,633, ?led
November 25, 1957, now abandoned, in the name of
Hewitt D. Crane and assigned to the assignee of the pres
ent invention, there is described a core register having a
novel transfer circuit requiring no diodes or other im
pedance elements in the transfer loops between cores.
The basic binary storage element of this circuit is an
annular core having an input and output aperture therein.
The binary zero digits are stored in the form of ?ux 20
oriented in the same direction in the core on either side
dicated by the arrows in FIG. 2. vThe core is then said to
be in the set or binary one state.
The signi?cant aspect of the transfer circuit described
in the above-identi?ed copending application is that with
a given number of turns linking one of the small aper
tures in the core and with the core in its cleared state as
shown in FIG. 1, a current exceeding a threshold value It
must be provided ‘to change the core to its set state as
shown in FIG. 2. If the current does not exceed this thres
hold level, substantially no ?ux is switched around the
core. The aperture is said to be “blocked” when the cur
of the respective apertures, while the binary one digits
are stored in the form of ?ux extending in opposite direc
rent passing through the aperture must exceed the thres
tions on either side of the respective apertures. Trans
hold value It in order to switch any flux in the core ele
fer is effected by applying a current pulse of predeter 25 ment.
mined magnitude to a coupling loop linking one aperture
On the other hand, if the core is already in its set state,
in each of two cores, one core constituting a transmitting
a very small current, substantially less than the thres
core and the other core constituting a receiving core.
hold value It, causes flux to switch locally about the aper
The present invention utilizes the principles of the
ture. In this case the aperture is said to be “unblocked.”
above-identi?ed copending application to accomplish the
Thus if a current slightly less than the threshold current
logical “and” function. According to the present inven
I, is passed through an aperture in a core element, ?ux
tion, in order to transfer a binary one to a receiving core
will be switched or not switched within the core depend—
element, the identical ?ux condition representing a binary
ing upon whether the core is in its cleared state or its set
one digit must be established on each of a plurality of
state, i.e., depending on whether the aperture is blocked
35 or unblocked.
transmitting core elements.
I
In brief, the circuit of the present invention comprises
This principle is used to provide a circuit producing an
a plurality of input or transmitting core elements and a
“and” function, as shown in FIG. 3. First, consider a
single output or receiving core element. Each of the
transmitting core element 22 having an input aperture 24
core elements is made of magnetic material having a high
and an output aperture 26. The transmitting core ele
?ux retentivity, such as ferrite, the core elements being 40 ment 22 is coupled to a similar receiving core element 28.
annular in shape and having at least two small aper
having an input aperture 30 and an output aperture 32.
tures therein. Each of the core elements is provided
Each of the core elements 22 and 28 is provided with a‘
with a winding linking the annular core element through
clearing winding which passes current through the cen
one of the apertures, the windings being connected in
tral opening of the core element, as indicated at 34 and
parallel across a pair of terminals. Means is provided 45 36 respectively. Suitable means is provided for generating
for applying a transfer pulse across the terminals, the
clearing pulses through the respective windings 34 and’
pulse being of a magnitude to produce a total current ?ow
36, as by means of clear pulse sources indicated at 38 and
through the parallel windings which is slightly less than
'40 respectively. Thus each of the core elements 22 and
twice the threshold current required to reverse ?ux
28 may be placed in the cleared state in ‘which all of the
50 ?ux is saturated in a clockwise direction in the manner
around any one of the annular elements when in a satu
rated condition. In this manner, unless all the input cores
are set, i.e., unless the flux can be switched locally about
the apertures of the transmitting cores, no ?ux change is
effected in the receiving core in response to the transfer
described above in connection with FIG. 1. The output
aperture 26 of the core element 22 is now blocked, as is
the output aperture 32 of the core element 28.
A transfer loop 42 links the core element 22 through
55 the output aperture 26 and the core element 28 through
pulse.
'
‘For a more complete understanding of the invention,
the aperture 30. A transfer pulse source 44, having a
reference should be had to the accompanying drawings,
constant current characteristic, is coupled across the
wherein:
>
transfer loop 42. With both the core elements 22 and
FIGS. 1 and 2 show a ferrite magnetic core element
28 in their cleared state, the current ?ow produced by
such as used in the present invention in two conditions of 60 the transfer pulse source 44 divides between the por
flux orientation; and
tion of the loop 42 linking the output aperture 26 and
FIG. 3 shows a circuit according to the present inven—
the portion of the loop linking the aperture'30. The
tion for providing a logical “and” function and using the
core elements of the type shown in FIGS. 1 and 2.
‘
resistance in the two windings in the loop 42 is pref
erably arranged so that a substantially equal number of
Consider an annular core, such as indicated'at 10 in 65 ampere-turns links the core 22 and the core 28. The
FIGS. 1 and 2, made of a magnetic material such as fer
current split is such that the current through each branch
rite, having a square hysteresis loop, i.e., a material hav
ing a high ?ux retentivity or remanence.
The annular
core is preferably provided with two small apertures 12
of the loop 42 is below the threshold required to switch
?ux in the respective cores and unblock the output aper
‘tures. ,As a result, with both the cores cleared, a trans?
and 14, each of which divides. the annular core into two 70 fer pulse has no effect on either core.
' If, however, a large current has been pulsed through
parallel ?ux paths as indicated by the arrows. If a large '
3,030,519
3
4
the input aperture 24 of the transmitting core element
cation, Serial No. 704,511, ?led December 23, 1957, in
22 at X so as to put the core .element 22 in its set state
the name of Hewitt D. Crane and assigned to the assignee
of the present invention.
and unblock the output aperture 26, corresponding to the
?ux condition shown in FIG. 2, a different result takes
place when a transfer pulse is generated by the source
44.
Thus as shown in FIG. 3,
bias windings are provided on each of the core elements
as indicated at 60, 62, 64 and 66. The bias windings are
connected in series with each other and in series with
the output of the transfer pulse source 44. One set of ,
In the latter case a much smaller current is re
quired to reverse flux locally about the unblocked output
aperture 26 in the transmitting core 22. As a result,
turns that has been found to give satisfactory operation
with the core 22 in its set state, when a transfer pulse
as follows:
is applied across the loop 42, the current through the 10 Transfer loop windings linking the transmitting cores12 turns.
aperture 26 is sufficiently large to switch ?ux locally
Transfer loop linking the receiving carer-11 turns.
about the aperture 26‘. The impedance of the branch
Bias windings linking the transmitting cores——2 turns.
of the transfer loop 42 linking the aperture 26 is thereby
Bias windings linking the receiving core-—-3 turns.
momentarily increased due to the counter EMF gen
erated by the switching ?ux. As a result, the current 15 It should be understood, however, that operation of the
“and” circuit does not depend on the use of bias as such.
through the branch of the transfer loop 42 linking the
Moreover, the set of turns listed above is only one ex
receiving core element 28 through the aperture 39‘ in
ample of many sets of turns which are operative.
creases above the threshold level required to switch flux
From the above description it will be seen that a
about the central opening of the annular core element
28. As a result the core element 28 is left in its set state, 20 circuit is provided which accomplishes the"‘and” func
tion. Only if all of the input or transmitting core
following a transfer pulse from the source 44, when the
elements are set can the output or receiving core element
transmitting core 22 is initially in its set state, thereby
be set in response to a transfer pulse 44. In principle,
unblocking the output aperture 32.
any number of transmitting core elements may be con
According to the present invention, to provide a circuit
Winding 34 from the clearing pulse source 38 is arranged
nected in parallel. The advance pulse applied to the
transfer loop, however, remains at the same current level.
In practice, however, even the transmitting core elements
to link each of the transmitting cores 48, 46 and 22 in
series for clearing all of the transmitting cores simul
the corresponding parallel branches of the transfer loop,
having the logical “and” function, additional transmitting
core elements 46 and 48 are provided. The clearing
that are in their set state draw some current through
taneously and blocking all the output apertures. The 3 O thereby diverting a corresponding current from the re
ceiver core branch. This limits the practical number]
transmitting coreelements 48 and 46 have separate in
of parallel branches inrthe transfer loop. The circuit has .
put apertures 50 and '52 respectively, to which separate
been found to operate reliably with at least three input
input current pulses at Y and Z may be applied. Out
core elements.
'
put apertures 54 and 56 respectively of the core elements
'
'46 and 48 are linked by windings which are connected in 35 'What is claimed is:
1. A logical “and” circuit comprising a plurality of in
parallel with each other and in parallel with the trans
put core elements and a single output core element of
fer loop 42. Thus with four core elements as shown,
magnetic material having a high ?ux remanence, each of
the current from the transfer pulse source 44 divides be
the coreelements being annular in shape with an input
tween four parallel branches.
It will be seen that separate inputs X, Y, and Z are 40 and an output aperture extending through each annular
core element, means including windings linking each of
provided for each input core element by means of which
the input core elements through the central openings
each'of the transmitting core elements 22, 46 and 48
therein provided by their annular shape for clearing all
respectively may be placed in the set state and the corre
the flux in the input core elements to saturation in one
sponding output apertures unblocked. With all of the
core elements in the set state, the impedance of the 45 direction, whereby the output aperture of each of the in- .
put core elements are blocked, a plurality of input wind
branches of the transfer loop linking the transmitting
core elements is high, so that a substantial portion
ings, each input core element having an input winding .
of the current will pass through the input aperture 30
linking the core element through an input aperture, where—
by the output apertures of anyrselected ones of the input
of the core element 28.
In this manner the core element
core elements may be unblocked by a current pulse
28 is changed to its set condition.
through the corresponding input windings, means includ
However, if only two or less of the transmitting core
ing a'winding linking the output core element through
elements 22,46 and 48 are placed in the set condition,
the central opening therein provided by the annular shape
insufficient current will pass through the branch of the
of the core element for clearing all the ?ux in the output
transfer loop 42 linking the receiving core element 28
through the input aperture'30 to switch any flux therein. 55 core element to saturation in one direction, a transfer
circuit coupling each of the input core elements to the
This is because at least one of the parallel branches of
output core element, the transfer circuit including wind-'
the transfer loop linking the input core elements presents
ings linking each of the input core elements through the’
a low shunting impedance, diverting current from the
output apertures-thereof and a winding linking the out
branch linking the output core element. Thus the re
ceiving core element 28 will remain in its cleared state. 60 put core element through the input aperture thereof, the
respective windings of the transfer circuit being con
For example, if the transmitting core elements 46 and 48
nected in parallel with each other to provide a plurality
are in their set states and the transmittingcore element
of parallel current paths, and means for applying a trans-.
22 is in its cleared state, current divides substantially
fer pulse across the parallel windings of the transfer cir
equally between the portion of the transfer loop linking
the transmitting core 22 through the aperture 26 and 65 cuit, the pulse being of a magnitude to produce a total
current flow through the transfer circuit equal toslightly
less than twice the current required to produce ?ux
the receivingcore element 28 through the aperture 30,
in which. case, as pointed out above, the ampere-turns
linking the core element 28 is insufficient to switch any
'?ux around the central opening of the annular core
element.
"
.
-
_
.
It is desirable that bias be used on each of the trans
mitting and receiving cores in order to extend the operat
ing current'range of the transfer pulseand to control‘
the threshold level in'the receiving core according to
reversal in a core element when in a saturated'condition‘
as produced by said clearing means.
70
2. A logical “and" circuit comprising a plurality of in
put core elements and a single output core element of
magnetic material having a high '?ux remanence, each of
the core elements being annular ‘in shape to provide a a
a large central aperture,.with an input and an output apes
the principlesv set forth in detail ‘in the copending japplii 75 ture extending through each annular core element; means.
V
3,030,519
6
for clearing all the ?ux in the input core elements to
saturation in one direction, whereby the output aperture
5. A logical “and” circuit comprising a plurality of in
put core elements and a single output core element, each
of each of the input core elements are blocked, a plural
of said core elements being made of magnetic material
having a high ?ux retentivity, the core elements further
ity of input windings, each input core element having an
input winding linking the core element through an input
aperture, whereby the output apertures of any selected
being annular in shape to provide a large central aperture,
and having at least two small apertures therein, each of
ones of the input core elements may be unblocked by a
the core elements having a winding linking the annular
core element through one of said apertures, the windings
means for clearing all the ?ux in the output core ele
being connected in parallel across a pair of terminals, and
ment to saturation in one direction, a transfer circuit 10 means for applying a transfer pulse between said termi
coupling each of the input core elements to the output
nals.
core element, the transfer circuit including windings link
6. An “and” circuit comprising at least three annular
ing each of the input core elements through the output
core elements of magnetic material having a square hys
apertures thereof and a winding linking the output core
teresis characteristic, each of the core elements having
element through the input aperture thereof, the respective 15 a large central aperture and at least a pair of small
windings of the transfer circuit being connected in parallel
apertures extending therethrough, one of the core ele
with each other to provide a plurality of parallel current
ments being an output element and the remainder of
paths, and means for applying a transfer pulse across the
the core elements being input elements, a plurality of
current pulse through the corresponding input windings,
parallel windings of the transfer circuit, the pulse being
input windings, one input winding linking one of the
of a magnitude to produce a total current flow through 20 input core elements through one of said pair of small
the transfer circuit equal to slightly less than twice the
apertures, a plurality of transfer windings, one transfer
current required to produce ?ux reversal in a core ele
winding linking one of the core elements through one
ment when in a saturated condition as produced by said
of said small apertures, the transfer windings linking
clearing means.
the input core elements being connected in parallel with
3. A logical “and” circuit comprising a plurality of in 25 each other and in parallel with the transfer winding link
put core elements and a single output core element of
ing the output core element, and means for applying a
magnetic material having a high ?ux remanence, each of
transfer pulse across the parallel paths formed by the
the core elements being annular in shape to provide a
transfer windings linking the input core elements and the
large central aperture, with an input and an output aper
single transfer winding linking the output core element,
ture extending through each annular core element, means 30 the current level of the transfer pulse being below the
for clearing all the ?ux in the input core elements to sat
threshold required to switch a substantial amount of flux
uration in one direction, whereby the output aperture of
in any of the core elements when they are all saturated
each of the input core elements are blocked, a plurality
with all the ?ux in one direction.
of input windings, each input core element having an
7. An “an ” circuit comprising at least three annular
input winding linking the core element through an input 35 core
elements of magnetic material having a square hys
aperture, whereby the output apertures of any selected
teresis
characteristic, each of the core elements having
ones of the input core elements may be unblocked by a
a large central aperture and at least a pair of small aper
current pulse through the corresponding input windings,
tures extending therethrough, one of the core elements
means for clearing all the flux in the output core element
being an output element and the remainder of the core
to saturation in one direction, a transfer circuit coupling 40
elements being input elements, a plurality of transfer
each of the input core elements to the output core ele
windings, one transfer winding linking one of the core
ment, the transfer circuit including windings linking each
elements through one of said small apertures, the trans
of the input core elements through the output apertures
fer
windings linking the input core elements being con
thereof and a winding linking the output core element
nected in parallel with each other and in parallel with
through the input aperture thereof, the respective wind
45
ings of the transfer circuit being connected in parallel
the transfer winding linking the output core element,
with each other to provide a plurality of parallel current
paths, and means for applying a transfer pulse across the
paths formed by the transfer windings linking the input
and means for applying a transfer pulse across the parallel
core elements and the single transfer winding linking
4. A logical “and” circuit comprising a plurality of in 50 the output core element, the current level of the transfer
pulse being below the threshold required to switch a
put core elements and a single output core element, each
substantial amount of ?ux in any of the core elements
of said core elements being made of magnetic material
having a high ?ux retentivity, the core elements further ‘ when they are all saturated with all the flux in one di
rection.
being annular in shape to provide a large central aper
ture, and having at least two small apertures therein, each 55
References Cited in the ?le of this patent
of the core elements having a winding linking the annular
UNITED STATES PATENTS
core element through one of said apertures, the windings
being connected in parallel across a pair of terminals,
2,741,758
Cray ________________ __ Apr. 10, 1956
means for applying a transfer pulse between said termi
2,742,632
Whitely _____________ __ Apr. 17, 1956
nals, the pulse being of a magnitude to produce a total 60 2,896,194
Crane _______________ __ July 21, 1959
parallel windings of the transfer circuit.
current ?ow through the parallel windings equalto slight
ly less than twice the threshold current level required to
reverse ?ux around any one of the annular core elements
when in a saturated condition.
OTHER REFERENCES
Proceedings of IRE, vol. 44, issue 3, pp. 321-332,
March 1956, by J. Rajchman and Lo,
‘
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