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Publication numberUS3602908 A
Publication typeGrant
Publication dateAug 31, 1971
Filing dateJul 22, 1969
Priority dateJul 22, 1969
Publication numberUS 3602908 A, US 3602908A, US-A-3602908, US3602908 A, US3602908A
InventorsTetsusaburo Kamibayashi, Shintaro Oshima
Original AssigneeKokusai Denshin Denwa Co Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Wire memory matrix
US 3602908 A
Abstract  available in
Images(8)
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Claims  available in
Description  (OCR text may contain errors)

United States Patent [72] Inventors Shlntaro Oshirna Musashino-shi; Tetsusaburo Kamibayashi, Kitaadachi-gun, Saitama-ken, both of, Japan [21] Appl. No. 847,790

[22] Filed July 22, 1969 [4S] Patented Aug. 31, 1971 [73] Assignee Kokusai Densbin Denwa Kabusbilti Kaisha,

ah, Kokusai Denshin Denwa Co., Ltd. Tokyo-to, Japan June 22, 1963, May 13, 1963, May 13, 1963, Sept. 4, 1963, Jan. 28, 1963, Feb. 9, 1963, Feb. 9, 1963, Aug. 22, 1963, May 6,

[32] Priority 1963, Aug. 23, 1963 [33] Japan [31 38/31234, UM 38/3481 1, 38/23925,

38/46509, 38/3079, 38/9650, 38/9648, 38144164, 38123314 and UM 38/6492? Confirmation of application Ser. No. 309,469, Sept. 17, 1963, now abandoned.

[54] WIRE MEMORY MATRIX Primary Examiner-Stanley M. Urynowicz, .lr. Attorney-Robert E. Burns ABSTRACT: Magnetic matrix memory apparatus comprises a set of juxtaposed row conductive wires and a set of juxtaposed column conductive wires arranged orthogonally and adjacent to but insulated from the row conductive wires. Each of the row conductive wires is composed of a conductive spring wire having directly and uniformly deposited thereon a ferromagnetic thin film having substantially rectangular hysteresis characteristics and an inherent anisotropy. At least one of the sets of conductive wires is bonded to a sheet of insulation substratum. The ferromagnetic thin film of each row conductive wire forms closed magnetic circuits with respect to flux caused by current passed through the wire. Means is provided for applying an information signal to at least one wire of one of the sets of wires and for applying an exciting signal to at least one of the other set of wires. The inherent anisotropy of the thin film is established in a plane substantially orthogonal to the axis of the conductor to be employed for applying the information signal whereby a bit of information is stored in the ferromagnetic thin film deposited around at least one selected intersection between the two sets of wires in the state of direction of the residual magnetism of the magnetic thin film when selection is made by energizing with the information signal and the exciting signal at least one selected row conductive wire and at least one selected row conductive wire and at least one selected column conductive wire. A bit of information thus stored isread out from at least one wire employed for applying the information signal as an output signal having substantially the same amplitude and either of opposite polarities determined by the direction of the residual magnetism. of the residual magnetism of the magnetic thin film when selection is made by energizing with the information signal and the exciting signal at least one selected row conductive wire and at leastone selected column conductive wire. A bit of information thus stored is read out from at least one wire employed for applying the information signal as an output signal having substantially the same amplitude and either of opposite polarities determined by the direction of the residual magnetism.

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WIRE MEMORY MATRIX v This is a continuation application of our application Ser.

No. 309,469 filed Sept. 17, 1963, and now abandoned.

This invention relates to a memory matrix, and more particularly, it relates to a wire memory matrix using conductive wires with ferromagnetic thin film deposited thereon.

Although there have been proposed and in use various kinds of memory apparatuses as an important component member and row conductors which are so arranged as to intersect one another at each of said spots. In the case of the former example,the effect of eddy currents is negligible due to the characteristic of the ferrite, and moreover, thanks to recent research and development efforts, it became possible to obtain apparatus of small size with short access time, although there is a limitation to the improvement of its operating speed because of the fact that the speed of magnetization reversal of the ferrite is comparatively slow. Furthermore, in its manufacture, ring-shaped ferrite magnetic cores which are to be' allocated for the storage of one bit'of information are to be composed by securing each of said cores, one by one, with respective column conductors and respective row conductor. Hence, it s not suitable for mass-production, thus making it expensive and increasing the power consumption. Also, there is a limitation in its miniaturization, and its Curie point is comparatively low.

On the other hand, the latter memory apparatus wherein spots of magnetic thin film are used has faster operating speed because of a high speed of magnetization reversal speed caused by a characteristic of the ferromagnetic metallic thin film as well as other excellent features such as very small power consumption and wider range of operating temperature. However, it is difficult to make uniform products in continuous and mass-production system on account of its manufacturing process wherein a vacuum evaporation method is used mostly. it is especially difficult always to realize the uniform establishment of the magnetization easy axis which is an essential requirement. For this reason, conventional memory apparatuses of ferromagneticthin film type are expensive and limited to comparatively small capacity, and have not yet been made in any forms suitable for mass-production.

. An object of this invention is to provide a novel and inexpensive magnetic thin film matrix memory apparatus which is free from such defects as mentioned above, can sufficiently utilize the excellent characteristics peculiar to ferromagnetic thin film, and moreover, possesses small dimension, large capacity, ease of its manufacture and suitability for massproduction and can reproduce a uniform property in its production.

This and other objects of the invention are attained by a memory apparatus which comprises a set of juxtaposed row conductive wires and a set of column conductive wires arranged substantially orthogonal to and close to but insulated from the row conductive wires. Each of the row conductive wires has deposited directly and uniformly thereon a ferromagneticfilm having a substantially rectangular hysteresis characteristic and an inherent anisotropy. At least one of the sets of conductive wires is bonded to an insulation substratum. The ferromagnetic thin film-of each of the row conductive wires forms closed magnetic circuits with respect to flux caused by current passed through the wire, means is provided for applying an information signal to at least one conductive wire of one set and for applying an exciting signal to at least one wire of the other set. The inherent anisotropy of the thin film is established in a plane substantially orthogonal to the axis of the conductor to be employed for applying the inforromagnetic thin film deposited around at least one selected inmagnetic thin film which comprises a substratum coated with 1 spots of ferromagnetic thin film in matrix form and column tersection thin between said two sets of wires in the direction of the residual magnetism of the magnetic film when selection is effected by energizing with the information signal and the exciting signal at least one selected tow conductive wire and at least one selected column conductive wire. A bit of information is read out, from at least one selected wire employed for applying the information signal, on anoutput signal having substantially the same amplitude and either of opposite polarities detennined in accordance with the direction of the residual magnetism.

The invention, both as to'its construction and operation together with further advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a view showing the construction of a memory wire to be used as a memory element of a wire memory matrix embodying the features of this invention;

FIGS. 2(A), (B) and (C) are schematic views illustrating the operating principle of a wire memory" matrix embodying the features of this invention;

FIGS. 3, 5, and 6 are waveform diagrams illustrating the operating principle of a wire memory matrix embodying the features of this invention; 7

FIG. 4 is a characteristic curve of magnetic hysteresis illus- FIGS. 10 (A), (B), (C), and (D), are perspective views, and

FIG. 10(E) is a cross-sectional view illustrating basic examples of the invention;

FIGS. 11, 12, 13, 14,'I5(A), 15(3) and 16 are perspective views of the other embodiments of the present invention;

FIG. 17 is a view showing an embodiment of this invention, having short ring means;

FIGS. I8 and (B) are, respectively, a perspective view and a sectional view, and FIG. 19 is a perspective view, showing shielding means of a memory matrix of this invention;

FIGS. 20 (A), 20 (B), and 21 are perspective views showing other embodiments of this invention; and

FIG. 22 is a perspective view showing one example of holding means for the wirememory matrix of the present invention.

First, a memory wire to be used as the memory means of a magnetic memory matrix embodying the features of this invention will be explained.

. The memory wire 3 as shown in FIG. 1 comprises a COI'ldL-IC- tive core wire 1 made of diamagnetic body, such as copper, beryllium copper or phospher bronze, or paramagnetic boily, such as aluminum, on which is deposited uniformly and directly a ferromagnetic thin film 2, such as permalloy,;by means of electric or chemical plating as well as vacuiim evaporative deposition. 3

Employment of said elastic material in the core wire I isieffective to avoid deterioration of characteristics caused magnetostriction of the magnetic substance. i

It is possible with the magnetic thin film 2 to form a closed magnetic circuit in the circumferential direction of the wire I, because the wire 1 is coated with a magnetic thin film. Since the thin film 2 covers the wire 1 completely, the influence? of the external magnetic field will not exert any effect on the wire 1 therein due to its magnetic shielding effect.

The magnetic thin film 2 can be magnetized efficiently "by the electric current passing through the wire 1 because thewire 1 is placed very close to the magnetic thin film 2. Output signals produced by a change in magnetic flux caused by changes in the direction or in the intensity of magnetization of the magnetic thin film 2 can be derived efficiently from the wire 1. This is an important characteristic of the wire memory matrix of a magnetic memory apparatus according to this invention.

The direction of easy axis of the magnetic thin film is usually established in the circumferential direction or the longitudinal direction of the wire I. The direction of this easy axis is to be determined depending upon the condition of coating treatment of the magnetic thin film 2.

Next, a wire memory matrix according to this invention wherein a memory wire is used will be disclosed.

The principle of a wire memory matrix according to this mvention will be explained with reference to FIGS. 2( A) to (C) and 3.

FIG. 2(A) illustrates the case in which the easy axis is in the axial direction and the conductive wire 6 is made to intersect almost orthogonally with the memory wire 3. Both wires 3 and 6 are insulated relative to each other. In this case, a pulse current Ii for driving is made to flow through the memory wire 3, and an information current Ii+ (or Ii-) is made to flow through the conductor 6. The time relationship between the pulse current Id and Ii-l-(or Ii-) is as shown in FIG. 3. That is, when a pulse current Id is impressed on the memory wire 3 first at 1,, the current Id will flow mostly to the wire 1 because its resistance is smaller than that of the thin film whereby a magnetic field will be distributed in the circumferential direction of said wire 1. The magnetic thin film 2 will be magnetized in Y direction by this magnetic field. This magnetiza- 'tion in Y direction will be the same regardless of whether the residual magnetism is in X direction or Xb direction. Next, when an information current li+ (or Ii) is impressed on the wire 6 during the duration of the pulse current Id at t,, magnetization vector of the magnetic thin film 2 caused by the information current will tum either to direction Xa or Xb depending on its polarity. Therefore, a resultant magnetization vector composed of the drive current Id and the information current lr'+ (or Ii) will be turned either in direction X- or X- which is in the position between the axial direction and the circumferential direction, depending upon whether the polarity of the information current is or When a drive pulse current Id is removed at there will remain only the axial component of the magnetization vector in the direction X+ or the direction X, whereby said component in return will be written-in and memorized as the residual magnetism of the thin film 2 at I when the information signal has been removed. That is, if the polarity, or of the information signal is made to correspond, for example, to I," 0" of the binary information, then the information can be memorized as the direction of the residual magnetism of the magnetic thin film 2 located at the intersection of the wires 3 and 6. When the information thus memorized is to be read out, the drive current Id is made to fiow to the memory wire 3. Then the magnetization vector will rotate from the axial direction of the memory wire 3 to the circumferential direction thereof, whereby a read out output current corresponding to the differential value of the change in magnetic flux due to said rotation will be read out from the wire 6. As shown in FIG. 3, an output current lP-lor Ipis read out, the polarity of said current corresponding to the content of the memorized informatron.

FIG. 2(B) shows the case, wherein the easy axis is in the circumferential direction of the memory wire 3, whereby a driving pulse current Id is made to flow to the wire 6, and an information signal current Id+ (or Ii-) is made to flow through the memory wire 3, in the same sequence as that in FIG. 3. As easily analogized from the case of FIG. 2(A), the resultant magnetization vector of both currents Id and Ii is pointed in the direction X+ or X--, and the writing-in is to be made in the direction Ya or Yb which is the circumferential direction of the memory wire 3. The output current will be read out from the memory wire 3. FIG. 2(C) shows two pieces of memory wire 3 connected in series whereby the output current will become twice as much as that in the case of using one piece of memory wire.

The foregoing explanation is based on a destructive sensing system. However, the memory matrix according to this invention is also applicable to a nondestructive sensing system. The functions of the reading and writing will be explained further in detail hereinafter inclusive of the principle of the nondestructive sensing system.

In general, when a switching magnetic field H, which is in parallel with the direction of the easy axis and a lateral magnetic field H, which is perpendicular to said H. are applied simultaneously thereafter varying said lateral magnetic field H,, the magnetization hysteresis characteristic of the magnetic thin film viewed from the direction of the switching magnetic field I-I will vary greatly. That is, as shown in FIG. 4, if the loop characteristic of the thin film 2, when the lateral magnetic field was not impressed, is as shown by the curve (1), the coercive force would decrease gradually with the increase in intensity of the lateral magnetic field l-I,, thereby converting the loop characteristic to a curve (2) and finally to a curve (3) having no loop characteristic. As can be understood from the curves (1), (2) and (3), in accordance with increase in the intensity of the lateral magnetic field H,, the intensity of a switching magnetic field required for magnetization reversal will have to be decreased. l

The function of said writing and reading will be explained in connection with FIG. 4. Since no pulse current is applied at t, as shown in FIG. 3, the magnetic thin film 2 disposed at the intersection of the memory wire 3 and the wire 6 is in the state of curve (1). Assuming that an information is memorized in the form of residual magnetism as shown by a point aflwhen the drive pulse current Id is made to flow at the time t,, the lateral magnetic field resulting therefrom will be impressed on the magnetic thin film 2, whereby the magnetic hysteresis characteristic will become like the curve (2) and, at the same time, said magnetization will move from the point a to the point b. As mentioned heretofore, this fact corresponds to rotation of the magnetization vector and a readout output equivalent to the differential value of the change in magnetic flux caused by said rotation will be induced at the memory wire 3 (or the wire 6), thereby the reading-out of memorized content is carried out. This read output will become larger in proportion to the amount of change of magnetic fiux as represented by a section a b or to the rise time of the drive pulse current Id. When the information pulse signal Ii+is applied at the time the magnetization will move from the;point b to a point 0, thereby causing magnetization reversal. At the time 1 the drive pulse current will disappear and only the information pulse signal Ii-lwill remain. Therefore, thejmagnetic hysteresis characteristic will return to the state of curve (1), thereby magnetization will move from the point e to a point d. A pulse current which is to be generated at this time will be disregarded. Finally, at the time t, the information pulse signal li+ will disappear also, thus causing the magnetization to reach from the point d to a point e and then to be settled down. That is, the information pulse signal l+ will be written and memorized in the state of residual magnetism having a polarity corresponding to that of said signal Ii+. On the other hand when the information signal Iiis applied, contrary to the above case, magnetization will vary through a route zbg,- z i, -:g, thus returning to the point a. The read output current in this case corresponds to the information which has been memorized at the point a, but the polarity as well as magnitude of the residual magnetism will be kept unchanged. The function, when started from the point e, can be easily understood from the above description, that is, the route to be taken is either a route g,- or a route c g-f0; 1- in accordance with the information signal Ii-l (oi'Ii whereas the polarity of the output signal will be opposite to the case when started from the point a.

The above-described function based on the curves (1) and (2) corresponds substantially to a nondestructive sensirig, in which it is possible to read out an output signal corresponding to a memory information when the information signal is not impressed, and furthermore, after reading out, the memory state will be kept unchanged. However, when a lateral magnetic field due to the drive pulse current Id is larger than in the case of curve (2) and when it reaches a point where the magnetic thin. film 2 has been saturatedin a lateral direction, then the magnetic hysteresis characteristic will coincide with the characteristic in the direction of magnetization difficult axis, while a nondestructive sensing will become impossible, thus falling into a destructive sensing. That is, inthe case of starting from the point a, the magnetization of the thin film 2, due to the pulse currents as shgwn in FIG. 3, will change by way of either a route Q: LI:I C: -Zl i f or a route g-ejg g j' l. In the case of starting from thepoint e, the magnetization of the thin film 2 will hange by way of either a route gjl ig -1d a or a route gjhsglfigg ygsince magnetization is. pointed "at the point I: first when only the driver pulse current Id flows, whether the remanence occurs at the point a me is to be determined by the polarity of a noise signal which exists in an information current wire (3 or 6) which intersects at right angles-with the wire in which the drive current is flowing at that tune.

As can be understood from the above explanation, it is possible to make an nondestructive sensing when magnitude of the lateral magnetic field is selected so that the noise amplitude existing in the conductor for an information current does not exceed the coercive force of a magnetic hysteresis characteristic which is obtained by impression of the lateral magnetic field. It will become a destructive sensing if a lateral magnetic field being impressed is of such a magnitude that its coercive force becomes lower than the noise level.

Nexi, essential conditions for the magnitude of the drive pulse Id and information pulse Ii will be explained. First, in order that the memory contents of the thin film located at optional intersections are not to be destroyed by disturbance pulses, i.e. many information pulses to be applied to plural cross points composing the same row or same column, amplitude of the infonnation impulse Ii must be at least within a flat portion and below the curved portion in the curve (1) as shown in F IG. 4. That is, the magnitude of the magnetomotive force I-I, due to the information pulse Ii must be smaller than that of E in FIG. 4. On the other hand, if it is less than the saturation point in the curve (2), a perfect writing will not be performed, because a perfect saturation in magnitization would not be obtained. Therefore, it is desirable that the magnetomotive force H, be larger than I--I be larger than I-I, as shown in FIG. 4. Hence, the amplitude of an information pulse must satisfy the following equation;

In the foregoing description, both the drive current Id and the information current Ii were taken to be direct current pulse signals, but alternating current signals can also be used.

First, in connection with the case in which the drive current Id is AC and the information current Ii is DC pulse will be explained. In this case, both'currents Id and Ii are impressed on appropriate wire (3 or 6)'as shown in FIG. 2(A) or 2(B) according to the direction of the easy axis of the magnetized thin film 2. Examples of adrive signal an an information signal are illustrated in FIG. 5, in which writing-in is performed by an AC drive signal Id, and a DC information signal (Ii+ or I). In this case, the magnetization characteristic of the thin film 2 will contract from the .curve (I) to the curve (2) due to the impression of the AC drive signal Id and again restore to the curve (1), said action being repeated in the above manner. Thus, when a DC information pulse signal Ii is applied in the state of being magnetized at the point a, the magnetization reversal will take place when the coercive force becomes smaller than the amplitude of the information signal during the course in which the magnetization characteristic is changing from the curve ("1) to the curve (2), thereafter going through the same process as the case of pulse train as shown in FIG. 3 and will settle down at the point 2. Writing action in the cases of other state and polarity can easily be analogized from the case of FIG. 3 and therefore detailed explanation thereof will be omitted. Next, in the case of reading-out, an AC output signal with a frequency f will be induced in wires (6 or 3) which interset, at right angles, with the wires (3 or 6) when an AC drive signal id; with a frequency f/2 is applied on the latter wires. This output signal assumes either one of two states having phase difference 180 to each other according to the polarity of the residual magnetism thus written. For example, if the phase is assumed to be 0" phase when the residual magnetism is then it will be in w phase in case of The characteristic feature of this method is that the amplitude of the output signal Ip is proportional to the amplitude ofinformation signal Ii so long as the amplitude of the inforn iation signal Ii is small, thus making it possible to memorize analogue information signals by utilizing said characteristic. For this purpose, the magnetization characteristic of a magnetic substance should be such as to have a large coercive force and normal hysteresis characteristic rather than a perfect rectangular characteristic. 3

Next, in connection with the case in which the drive current Id and the information signal Ii are both AC will be explained. In this case, the drive signal has a frequency f/2 as shown in FIG. 6, and the information signal Ii has a frequency f and contains the information in a phase of 0" or 1r With regard to the impression of signals, the AC drive signal Id is impressed in such a manner that a magnetic field is formed along theimagnetization difficult axis of the magnetic thin film 2 while the information signal Ii is impressed so that its magnetic field is formed along the easy axis thereof. Therefore, in the case of FIG. 2(B) wherein the easy axis is in longitudinal direction, a drive signal id. having a frequency 172 is impressed on the wire 6 and an information signal Ii(0) or Li(1r) having a frequelncy f is impressed on the memory wire 3 in the case of writing-in. Similarly, in the case of reading-out, when a drive signal is applied to the wire 6, an output signal 112(0) or Ip(1r) is takeit out from the memory wire. In the case of FIG. 2(A), wherein the easy axis is in circumferential direction, a drive signal Id is applied to the memory wire 3 and an information signal Ii is applied to the wire 6 contrary to the said case.

A method of handling an information in a form of AC signal phase as shown in FIGS. 5 and 6 is extremely convenient when it is combined with parametrons and has a further advantage of making the periphery circuitries of a memory apparatus extremely simple and compact. 1

A wire memory matrix according to this invention will be illustrated, in greater detail, by the following examples.

FIG. 7 shows the most fundamental construction comprising a set of row conductive wires x x x x,, composed of juxtaposed memory wires 3 and column conductive wires y y y y,, which arearranged in such a manner as to intersect with said row conductive wires at substantially right angles, said wires of both kinds being mutually insulated. Each of the column conductive wires 6 is composed of a pair of conductors which are arranged'in parallel so as to maintain all the row conductive wires securedly therebetween. When a drive pulse current Id from a signal source S1 and an information signal pulse current Ii from a signal source S2 are respectively, impressed, as illustrated in the above description of the operating principle, on a selected column conductive wire and a selected row conductive wire of such compositions as described above, one bit of information will be memorized in a magnetiqsubstance (8, for example) which is located at the intersection point of said selected column conductive wire 6 and said selected row conductive wire 3. The energizing pulse currents impressed on said column conductive wire flow throughl said pair of conductors in opposite directions, whereby thei ferromagnetic substances at the intersection point are magnetized in the dame direction. According to said construction the resultant magnetic field caused by the current flowing through the conductive wire 6 is directed in parallel to the axis of a memory wire (3), so that an ideal magnetization such as described in connection with the operating principle, said magnetization being made to intersect the magnetization easy axis of the magnetic substance at right angle, will be obtained.

FIG. 8 shows an embodiment which is similar to that shown in FIG. 7. In this embodiment, the column conductive wire consists of a memory wire (3) and the row conductive wire consists of a conductive wire 6. The memory apparatus of this embodiment also can operate according to a principle which is almost the same as that in FIG. 7. Accordingly, for the sake of simplicity, a type shown in FIG. 7 will be explained principally in the following description.

The efficiency of magnetization of the magnetic substance in memory wire 3 caused by the current flowing in the conductive wire 6 is not so good because each of the column conductive wires is normally in point-contact. The arrangement shown in FIG. 9 has been devised so as to improve efficiency, wherein the pair of column conductive wires are arranged in parallel to fit securely along the circumference of each of the row conductive wires. That is, these parallel conductives wires are arranged in such a manner that one 6a of the conductive wires 6 covers almost half of the circumference of the row conductive wire 3 and the other conductive wire 6b covers the rest of the same circumference, thereby the conductive wires 6a and 6b are made to cover the row conductive wire almost completely, thus making a loop circuit which makes it possible to magnetize the magnetic substance in a very efficient manner by means of an electric current passing through the conductive wire 6.

In order to improve magnetization efficiency and to perform an ideal magnetization directed in a direction perpendicular to the easy axis of the magnetic substance, the column conductive wires are preferably composed of strip conductors as shown in FIGS. (A) and 10(B). FIG. 10(A) is an enlarged view of one of the intersection points and the actual arrangement thereof is shown in FIG. 10(8). The wires of each pair of the column conductive wires are opposed to each other, formed into wave form as shown in FIGS. 10(A) and 10(8) and maintained in separate insulating substrata 8a and 8b made of a material, such as synthetic resin. FIG. 10(C) illustrates the case, wherein each pair of said wires is bonded to one 8a of said substrata. Said bonding can be made by either embedding or adhesion. When two sheets of the insulating substrata 8a and 8b carrying the column conductive wires as shown in FIG. 10(C) are put together and each memory wire 3 is bonded at a notch portion 9 as shown in FIG. 10(D), encompassment of the conductive wires 6 at the intersection point will be secured and furthermore, when the flat portions 10 positioned between the notches of the substrata 8a and 8b are held by means of heat treatment or adhesive, this ideal structure can be maintained for a long time. FIG. 10(5) is a sectional view of said ideal structure.

Next, the invention will be explained in connection with the following examples of actual embodiments relative to the fundamental arrangement illustrated in FIGS. 7 and 8. In one example, each group of the conductive wires is bonded to an insulation substratum made of a synthetic resin or the like. A wire memory matrix according to this invention is provided with three groups of the conductive wires one of which is row conductive wires and the other two are two groups, each consisting of the wires 61: and 6b, of the column conductive wires which arranged in parallel go each other and separated by said row conductive wires. Therefore, several combinations of said three groups are possible inorder to bond said conductive wires on the insulating substrata. FIG. 11 shows the parallel column conductive wires 6a and 6b which are bonded on separate insulating substrata 12a and 12b respectively, wherein two each being bonded to either column conductive wires 6a and 6b in parallel thereto, and a memory wire 3 is secured between said substrata as shown in FIG. 11. The insulating substrata 12 a and 12b which are combined with said column conductive wire 6a and 6b can be manufactured according to a mass production method. Hence, the wire memory matrix having the abovementioned structure can be realized easily and economically. FIG. 12 shows another practical embodiment of the example shown in FIG. 11, in which the column conductive wires 6a and 6b (FIG. 12 shows 6 a only) are prepared by print-wiring.

FIG. 13 shows another embodiment wherein row conductive wires 3 are bonded to an insulating substratum 13 and then the column conductive 6a and 6b are combined thereto.

FIG. 14 shows three groups of the conductive wires (3, 6a, 6b) which are bonded to and combined with separate insulating substrata 13, 12a, and 12b, respectively.

In each of said examples, the column conductive wires were assumed to be composed of one pair of parallel wires 6:: and 6b, so that the exciting currents flowing through said wires 6a and 6b of each pair must have opposite polarities. In this case, it is possible to supply an exciting current through only one terminal by connecting the said wires of a pair in series as shown by dotted line in FIG. 14.

FIGS. 15(A) and 15(8) show an embodiment wherein the column conductive wires 6a and 6b connected in series are combined with an insulating substratum 14 which is bent. In practice, however, a conductive wire 6 may be bonded to a sheet of insulating substratum 14 which thereafter is bent. The row conductive wire, as shown in FIGS. 15(A) and (B), can be adapted to be covered by and bonded to the substratum 14, whereas FIG. 16 shows the case in which the row conductive wires are also bonded to the substratum 15.

Instead of bonding the wires in the state of separate groups, the wires may be bonded, as a whole, to one sheet of the substratum. Although the complete assembly can be attained at once, all of the wires may be assembled into one single sheet after production of the members as illustrated in FIGS. 11 to 16.

Next, the method of magnetically isolating the thin film portions of the memory 3 and 5 from each other which are to be used as memory elements will be explained. Because of existence of the magnetic this films 2 covering uniformly the surface of said wires, magnetization reversal occurs not only on the thin films disposed at the specific intersection points, but extends to the thin films at the neighboring intersection points during the writing-in or reading-out process, thereby the memory contents may be destroyed or a smooth and efficient action can be damaged by diamagnetic current due to the fact that the thin films are interconnected. The above-mentioned phenomena occur is the exciting current flow through the wire 6 is greater than an appropriate value.

A method of removing a mutual interference between said adjacent memory elements will be explained. This method, employs short ring means for magnetically shielding the neighboring elements, said means being located on the row conductive wire. Therefore, when the arrangement is that the short ring means are put on each of the intervals between the neighboring magnetic materials disposed at the intersections points of the memory wire 3 and the column conductive wires y,, y the memory elements formed at each intersection portions will be magnetically isolated from each other, whereby it becomes possible to shorten the distances between the column conductive wires, to write in and read out information without being damaged by the mutual interference,and to increase bit density. One example of this means is shown in FIG. 17, wherein opposed conductive wires s s substantially identical to said pair of column conductive wires y,, y opposed but having no insulating layer on opposite sides can be associated as illustrated, whereby said conductive wires s,, 5 encompass each of memory wires 3 at a median part (for example, 23) between intersection portions (for example, 21, 22) to be use as a a memory element." In actual devices, said short ring means s,, s may be stuck on the substratum as well as column conductive wires y y y Next, means for magnetically shielding between energizing means of adjacent memory elements are described. This means is composed of magnetic substance on the conductive wires 6a and 6b except portions which are opposed at the intersections between the row conductive wires 3 and the column conductive wires 6a and 6b. One example of this means is illustrated in FIG. 18(B) wherein magnetic substances 33 encompass the conductive wires 6a and 6b. In this case, the magnetic substances 33 are not disposed at the portion 35 contacting with the memory wire 3. An insulation layer 34 is employed for isolating-between the memory wire 3 I for shieldingis uniformly disposed, as shown by y in FIG. 19,

on the conductive wire 6a and 6b or only at intersection parts as shown byy in FIG. l9..ln any case, since. magnetic fluxes caused bythe current flowing in the conductive wires 6a and 6b arealmost accepted into the memory wire 3 without. large leakage, magnetic substance to be used as adjacent memory elements are not magnetized unnecessarily.

,Although it is assumed. in all embodiments mentionedabove that each of the column conductive wires is composed of a pair of opposed conductive wires 6a and 6b, said column conductive wiresnot always need essentially to adopt such formatiomThat is, since energizing can be carried out so long as energizing'fields are applied in directions parallel with or perpendicular to the easy axis of the magnetic substance to be employed as memory elements, both of two sets of conductive wires 3 and 6 canbe merely disposed in the rectangular intersection relationship. I

t-One example of this is shown in FIGS. (A) and 20(B), whereinfno holding means of any type is necessary. More particularly, a set of row conductive wiresvand a set of .column conductive. wires are, respectively, bonded to two sheets of insulating' substratum and then associated together in layers. With reference to the1formation, it is equivalent to the combina tion of substrata I3 and 12a (or 12b) in FIG. 14. In order to increase the efficiency of energizing in actual case, it is adaptable that a plurality'of grooves are provided perpendicularly with the column;conductive wires 6 and then the memory ires 3 are held in these grooves. FIG. 21 shows an example thereof wherein grooves!) are provided in both side of a substratum 36 and the memory wires 3 are received therein to form a unitary whole.

As will be understood from the actual examples of the invention, as a means of supporting the entireapparatus, such substratum asmentioned above or an insulating plate 36 supporting an output terminal. as shown in FIG. 21 may be used. Still another method of holding a memory matrix between two insulating plates 37 may be used as shown in FIG. 22. In order to facilitate designing of terminals, and furthermore, to in crease the bit density, the. terminals can be taken out in such a manner that, in the case of column conductive wire being composed of a double wire,terminals of adjacent wire are led out in opposite directions and the terminals on one side of the device are taken out at every other pair. 7

The wire matrix according to this invention has the following advantages.

The first advantage consists inthat its operating speed has very fast. The memory wire 3 is especially high operating speed because thin film 2 can be provided with a thickness of 1p. without any deterioration of characteristics. For example, when a drive pulse signal having a rise time of 20 nanoseconds is used in the case of writing-in with a pulse signal as shown in FIG. 3, the time required for memorizing one bit of the information was approximately nanoseconds. Also, it is possible to obtaina large output current, because the magnetic substance intersecting the memory element and the output conductive wire are held together closely as mentioned above, or else, the output current can be taken out from itself. Regarding noise, since the row conductive wire intersects, at right angles, the column conductive wire, the leakage noise component due to mutual induction is small, and a signal-tonoise ratio over 30 db.- can be obtained. The bit density obtained was less than l l mm."/bit which makes it possible to obtain an extremely small memorylmatrix. Furthermore, the memory wire 3 can be produced at a speed of 60 m./hour, and the memory wire 3 can be manufactured at a still higher speed. As

aresult, the apparatus of this invention can bring about extremely remarkable industrial effects.

, Since it is obvious that many changes and modifications can be made in the above described details without departing from the nature and spirit of the invention, it is understood that the invention is not tobe limitedto the details described herein except as set forth in the appended'claims.

What we claim is:. i

l. A magnetic matrix memory apparatus, comprising a set of row conductive wires juxtaposed to one another and a set of column conductive wires arranged substantially orthogonal to and closely but insulatively against said row conductive wires,

magnetic circuits with respect to flux caused by a current which is passed through the corresponding row conductive wire, means for applying an information signal to at least one conductive wire of one of the sets of said row and column conductive wires, means for applying an exciting signal to at least one of the other set of said row and column conductive wires,

the inherent anisotropy of the thin film being established in a plane substantially orthogonal to the, axis of the conductor to be employed for applying the information signal, a magnetic substance encompassing respective column conductive wires at each of the intersection points toshield magnetic fluxes caused by adjacent conductive wires, whereby a bit of information is stored in the ferromagnetic thin film deposited around at least one selected intersection between said two sets of the conductive wires in the state of the direction of the residual magnetism of said magnetic thin film when selection is achieved by energizing, with the information signal and the exciting signal, at least one selected 'rowconductive wire and at least one selected column conductive wire, and a bit of information stored isread out, from at least oneselected conductive wire employed for applying the information signal, as anoutput signal having substantially the same amplitude and either of opposite polarities determined in accordance with the direction of the residual magnetism, j

1 I A magnetic matrix memory apparatus, comprising a set of row conductive wires juxtaposed to one another and a set of column conductive wires arranged substantially orthogonal to and closely but insulatively against said'row conductive wires, each of said row conductive wires being composed o a conductive spring wire having deposited thereon direcitly and uniformly a; ferromagnetic thin film having a substantially rectangular hysteresis characteristic and an inherent anisotropy, at least one of the sets of conductive wires being bonded to a sheet of insulation substratum, said ferromagnetic thin film of each of the row conductive wires forming closed magnetic circuits with respect to flux caused by a current which is passed through the corresponding row conductive wire, means for applying a direct current information signal to at least one conductive wire of one of the sets of said row and column conductive wires, means for applying an alternating current exciting signal to at least one of the other set of said row and column conductive wires, the inherent anisotropy of the thin film being established in a plane substantially orthogonal to the axis of the conductor to beemployed for applying the information signal, whereby a bit of information is stored in the ferromagnetic thin film disposed around Eat least one selected intersection point between said two sets of the conductive wires in the state of the direction of the residual magnetism of said ha ving twice the frequency of that of an exciting signal for reading film when selection is achieved by energizing, with the information signal and the exciting signal,

. at least one selected row conductive wire and at least one 3. A magnetic matrix memory apparatus, comprising a set of row conductive wires juxtaposed to one another and a set of column conductive wires arranged in pairs substantially orthogonal to and insulatively against said two conductive wires, each of said row conductive wires being composed of a conductive wire having deposited thereon directly and uniformly a ferromagnetic thin film having a substantially rectangular hysteresis characteristic and an inherent anisotropy, each pair of said column conductive wires opposing each other and holding all of said row conductive wires securely therebetween, the wires of each pair of said column conductive wires being bonded to separable insulation substrata in groups respectively, said ferromagnetic thin film of each of row conductive wires forming closed magnetic circuits with respect to flux caused by the current which is passed through the corresponding row conductive wire, pairs of conductive wires disposed in the same arrangement as said column conductive wires to encompass said row conductive wires so as to form loops at the spaces respectively between two adjacent intersection points of the two sets of conductive wires, means for applying an information signal to at least one conductive wire of one of the sets of said row and column wires, means for applying an exciting signal to at least one of Y the other set of said row and column conductive wires, the in herent anisotropy of the thin film being established in planes substantially orthogonal to the axis of the conductor to be employed for applying the information signal, whereby a bit of information is stored in the ferromagnetic thin film disposed around at least one selected intersection point between said two sets of the conductive wires in the state of the direction of the residual magnetism of said magnetic thin film when selec tion is achieved by energizing, with the information signal and the exciting signal, at least one selected row conductive wire and at least one selected column conductive wire, and a bit of information stored is read out, from at. least one selected conductive wire employed for'applying the information signal, as an output signal having substantially the same amplitude and either of opposite polarities determined in accordance with the direction of the residual magnetism.

4. A magnetic matrix memory apparatus, comprising a set of row conductive wires juxtaposed to one another and a set of column conductive wires arranged in pairs substantially orthogonal to and insulatively against said two conductive wires, each of said row conductive wires being composed of a conductive wire having deposited thereon directly and uniformly a ferromagnetic thin film having a substantially rectangular hysteresis characteristic and an inherent anisotropy, each pair of said column conductive wires opposing each other and holding all of said row conductive wires securely therebetween, the wires of each pair of said column conductive wires being bonded to separable insulation substrata in groups respectively said ferromagnetic thin film of each of the row conductive wires forming closed magnetic circuits with respect to flux caused by a current which is passed through the corresponding row conductive wire, means for applying an information signal to at least one conductive wire of one of the sets of said row and column conductive wires, and means for applying an exciting signal to at least one of the other sets of said row and column conductive wires, the inherent anisotropy of the thin film being established in planes substantially orthogonal to the axis of the conductor to be employed for applying the information signal, a magnetic substance encompassing respective column conductive wires at each of the intersection points to shield magnetic fluxes caused by adjacent column conductive wires, whereby a bit of information is stored in the ferromagnetic thin film disposed around at least one selected intersection point between said two sets of the conductive wires in the state of the direction of the residual magnetism of said magnetic thin film when selection is achieved by energizing, with the information signal and the exciting signal, at least one selected row conductive wire and at least one selected column conductive wire, and a bit of information stored is read out, from at least one selected conductive wire employed for applying the information signal, as an output signal having either of opposite polarities deter mined in accordance with the direction of the residual magnetism.

5. A magnetic matrix memory apparatus, comprisirig a set of row conductive wires juxtaposed to one another, and a set of column conductive wires arranged in pairs substantially orthogonal to and insulatively against two of conductive wires, each of said row conductive wires being composed of a conductive wire having deposited thereon directly and uniformly a ferromagnetic thin film having a substantially rectangular hysteresis characteristic and an inherent anisotropy, each pair of said column conductive wires opposing each other and holding all of said row conductive wires securely therebetween, the wire of each pair of said column conductive wires being bonded to separable insulation substrata respectively, said ferromagnetic thin film of each of the row conductive wires forming closed magnetic circuits with respect to flux caused by a current which is passed through the corresponding two conductive wire, means for applying a direct-current information signal to at least one conductive wire of one of the sets of said row and column conductive wires, and means for applying an altemating-current exciting signal to at least one of the other of sets of said row and column conductive wires, the inherent anisotropy of the thin film being established in planes substantially orthogonal to the axis of the conductor to be employed for applying the direct-current information signal, whereby a bit of information is stored in the ferromagnetic thin film disposed around at least one selected intersection point between said two sets of the conductive wires in the state of the direction of the residual magnetism of said magnetic thin film when selection is achieved by energizing, with the direct-current information signal and the alternating-current exciting signal, at least one selected row conductive wire and at least one selected column conductive wire, and a bit of information stored is read out, from at least one selected conductive wire employed for applying the direct-current information signal, as an output signal having twice the frequency of that of an exciting signal for reading out and either of two phase positions, differing by from each other, determined in accordance with the direction of the residual magnetism.

6. A magnetic matrix memory apparatus, comprising a set of row conductive wires juxtaposed to one another and bonded to a sheet of insulation substrutum a set of column conductive wires arranged in pairs substantially orthogonal to and insulatively against said row conductive wires, each of said row conductive wires being composed of a conductive wire having deposited thereon directly and uniformlya ferromagnetic thin film having a substantially rectangular hysteresis characteristic and an inherent anisotropy, each pair of said column conductive wires opposing each other and having all of said now conductive wires securely therebetween, said ferromagnetic thin film of each of the row conductive wires forming closed magnetic circuits with respect to flux caused by current which is passed through the corresponding row conductive wire, means for applying an information signal to at least one conductive wire of one of the set of said row and column conductive wires, means for applying an exciting signal to at least one of the other set of said row and column conductive wires, and the inherent anisotropy of the thin film being established in planes substantially orthogonal to the axis of the conductor to be employed for applying the information signal, a magnetic substance encompassing respective column conductive wires at each of the intersection points to shield magnetic'fluxes caused by adjacent wires, whereby a bit of information is stored in the ferromagnetic thin film disposed around at least one selected intersection point between said two sets of the conductive wires in the state of the direction of the residual magnetism of said magnetic thin film when selection is achieved by energizing, with the information signal and the exciting signal, at least one selected row conductive wire and at least one selected column conductive wire, and abit of information stored is read out, from at least one selected con- 3 ductive wire employed for applying the information signal, as an output signal having substantially the same amplitude and either of opposite polarities determined in accordance with the direction of the residual magnetism.

7. A memory apparatus according to claim 6, in which the 5

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7173847 *Nov 4, 2003Feb 6, 2007Magsil CorporationMagnetic storage cell
US8248845 *Jan 31, 2007Aug 21, 2012Magsil CorporationMagnetic storage cell
US20040233712 *Nov 4, 2003Nov 25, 2004Krish ManiMagnetic storage cell
Classifications
U.S. Classification365/61, 365/57, 365/135, 365/171, 365/139
International ClassificationG11C11/04, G11C7/02
Cooperative ClassificationG11C7/02, G11C11/04
European ClassificationG11C11/04, G11C7/02