Pulse Latched Matrix Switches

Abstract

A pulse-actuated reed switching matrix of the magnetically latching type in which the reed capsules are mounted flat on a printed circuit board providing the appropriate speech path connections, has row and column windings which are respectively printed on two substrates disposed in planes parallel to that of the reed capsules. The two substrates are formed by two sections of a flexible sheet of insulating material which are folded over each other so that the points of intersection of the column and row windings -- control locations -- register with one of the two contact blades of the reed capsule or capsules at the corresponding crosspoint while the other blade of each reed capsule is provided in a magnetic bias location of the matrix. Two embodiments are shown. In the first the reeds are of low-remanence magnetic material and a plate of semi-hard magnetic material, sandwiched between the two sections of the above flexible sheet has, interposed between its rows of control locations, rows of bias locations in which the plate is magnetically pre-polarized through its thickness in alternating directions. In the second embodiment each reed capsule has a reed blade of semi-hard magnetic material in the corresponding control location of the matrix, whereas the cooperating reed blade in the respective bias location is of permanent magnetic material. In both implementations coincident current selection is employed, and the pulses used for operating and for releasing a selected crosspoint are of opposite directions. BACKGROUND OF THE INVENTION The invention relates to pulse-actuated reed switching matrices, particularly for use in the switching network of communication systems such as telephone systems. The switching networks of many telephone systems of recent vintage use crosspoint matrices of reed switches as their principal building block. These switches employ sealed reed contacts which are opened and closed by energizing the associated control windings in a suitable manner. The reed contacts, or sets of reed contacts, when closed, serve to selectively establish a speech path through the network. Two different control techniques are available for bringing about the opening and closing of these contacts, viz.: (1) the current holding technique, and (2) the magnetically latching, or, as it is sometimes referred to, the "pulse latched" technique. The reed contacts used in the current holding technique are made of low remanence magnetic material such as nickel iron. When the control winding is energized from a source of continuous direct current, the nickel iron blades are mutally attracted. The contact gap is bridged and continuity is established from one reed to the other. The contacts remain closed as long as the operating winding -- or else a separate holding winding -- is kept energized. On deenergization of the winding in question, the reed blades spring back to their normal position, and the continuity is broken. In the pulse-latched technique, the reed blades typically are made of a semi-hard magnetic material of square hysteresis loop characteristics. The polarity of the semi-hard magnetic material can be switched from North to South or vice versa by momentarily subjecting the material to a high intensity magnetizing force of the required polarity. To generate such a momentary magnetizing field of high intensity, a pulse is applied to the control windings which causes the reed blades to be magnetized in the direction required to effect the opening or closing of the contacts. It may be mentioned that the reed blades of a pulse-latched switch need not always be made of a semi-hard switchable material, but that instead a conventional reed capsule with blades of low-remanence magnetic material can be used -- provided a separate member made from a semi-hard magnetic material is used in conjunction with the reed capsule. In such an arrangement, the semi-hard magnetic member is disposed externally of the reed capsule in close proximity to the reed blades. On pulsing the control windings, the semi-hard member is magnetized and the low-remanence blades of the reed capsule are closed or opened under the magnetic influence of the polarized member. In connection with the foregoing, reference is made for example to the article, "THE FERREED -- A New Switching Device," which appeared in the January, 1960 issue of the Bell System Technical Journal. The reed contacts of the pulse-latched matrix switch are closed by pulsing its control windings in a predetermined direction, and in order to open the contacts the windings are pulsed in a reverse direction. In the prior art arrangements of the foregoing kind this meant that each winding had to be wound in a specific direction, and that the windings then had to be interconnected to form rows and columns for the coordinate addressing of the crosspoint. This procedure is tedious and time-consuming, notwithstanding the fact that it is usually carried out under the control of highly specialized computerized machines. OBJECTS AND SUMMARY OF THE INVENTION Accordingly, it is the principal object of the present invention to provide a novel pulse-actuated reed switching matrix of the magnetically latching type which is of simplified design and less costly to manufacture, and which therefore avoids the aforementioned shortcomings of the prior art matrices of this kind. It is another object of the invention to provide novel components or sub-assemblies which may be used in such a simplified matrix. The foregoing objects are attained, by a design which utilizes printed circuit techniques to replace the wire wound control windings of the known matrices of the type in question. More specifically, the reed capsules are mounted flat on a printed circuit board providing the conventional speech path connections, (in the case of a telephone system); and there are substrate means superimposed on this board which, in parallel planes, carry the column and row windings for the selection of a given crosspoint. The aforementioned substrate means are preferably formed by two sections of a flexible sheet of insulating material which are folded over each other so that the points of intersection of the column and row windings, hereinafter referred to as the control locations, register with one of the two cooperating contact blades of the reed capsule or capsules at the respective crosspoint. The other blade of each reed capsule is provided in what may be referred to as a bias location of the matrix. Two principal implementations of this technique are disclosed. In the first embodiment the reeds are of the conventional low-remanence magnetic material, such as nickel iron, and a plate of semi-hard magnetic material, for example Remendur is sandwiched between the two sections of the above flexible sheet. Interposed between at least some of its rows of control locations, this plate has rows of bias locations in which the plate is magnetically pre-polarized through its thickness in alternating directions. In the second embodiment each reed capsule has a reed blade of semi-hard magnetic material in the corresponding control location of the matrix while the cooperating reed blade in the respective bias location is itself of permanent magnet material. In both implementations the polarity of the reed blade at the control location can be switched -- either through the medium of the Remendur plate or, in the case of the second embodiment, directly, by pusling the control windings thereby to bring about contact opening or closure. Also, in both embodiments coincident current selection is employed and the pulses used for operating and for releasing a selected crosspoint are of opposite directions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which:

FIG. 1A is a top view of the pulse latched matrix switch assembly according to the first embodiment of the invention, using conventional reed switches;

FIG. 1B is a side view of this assembly as seen from the left in FIG. 1A;

FIG. 2 is a top view, drawn at a reduced scale, of the printed circuit board of the assembly of FIGS. 1A and 1B, with some of the reed capsules inserted therein;

FIG. 3 is a top view, also drawn at a reduced scale, of the plate of semi-hard magnetic material used in the assembly of FIGS. 1A and 1B, showing the magnetic pre-polarization pattern generated therein;

FIG. 4, again drawn at a reduced scale, shows a flexible sheet of insulating material, prior to folding, to which the control windings for the matrix switch assembly, FIGS. 1A and 1B, have been applied by printed circuit techniques;

FIG. 5 is a top view of a sub-assembly comprising the flexible sheet of FIG. 4 and the polarized magnetic plate, FIG. 3, after the former has been folded over the latter;

FIG. 6A is an enlarged side view of a reed capsule overlaid by a section of the sub-assembly FIG. 5, schematically illustrating the latched condition of the reed capsule;

FIG. 6B is an enlarged side view similar to that of FIG. 6A except schematically illustrating the unlatched condition of the reed capsule;

FIG. 7 shows at an enlarged scale, a reed capsule with a permanently magnetized and a magnetically switchable reed blade, which may be used in the second embodiment of the invention for example;

FIG. 8 is a rear view, shown at a reduced scale, of the printed circuit board used in the second embodiment, omitting the printed wiring conductors representing the speech path, but indicating the location of the reed capsules in broken lines;

FIG. 9 shows, for the second embodiment and at a reduced scale, a flexible sheet of insulating material, prior to folding, to which the control windings for the corresponding matrix switch assembly have been applied by printed circuit techniques;

FIG. 10A is a top view of the pulse-latched matrix switch assembly of the second embodiment of the invention;

FIG. 10B is a side view of this assembly as seen from the right in FIG. 1A.

DETAILED DESCRIPTION

Referring first to FIGS. 1A and 1B which show the overall assembly of an 8 .times. 8 (2 wire) switching matrix according to the first embodiment of the invention in top view and side view respectively, the principal components of the matrix are a printed circuit board more specifically shown in FIG. 2, in which the reed capsules are inserted in pairs, such as 4, 5 or 6, 7; and superimposed on these capsules, in a plane or planes parallel to the latter and to the printed circuit board, is sub-assembly 13 which is specifically shown in FIG. 5. This sub-assembly contains the flexible circuit printed sheet 20, shown, prior to folding over, in FIG. 4, and the magnetic plate 10, FIG. 3, which is sandwiched between the top and bottom halves of the flexible sheet, FIG. 4. As shown particularly in FIGS. 1A and 1B, sub-assembly 30 is mounted on printed circuit board 1 by means of eight tubular spacers 16 and rivets 15 passing through these spacers.

The terminals such as 43, 46 of the contact blades of the reed capsules are inserted into printed circuit board 1 through holes 9 in a pattern best seen in FIG. 2. Board 1, FIGS. 1A, 1B and 2, in addition to serving as a mechanical support for the remainder of the matrix switch assembly, carries on both sides thereof the required matrix type printed circuit connections between the aforementioned terminals of the reed capsules and between these terminals and the tabs 3 of connector plug portion 2 which extends from the left edge, FIGS. 1A and 2, of the printed circuit board. These matrix connections -- which in the assumed example provide part of the switched transmission path of the telephone network -- are not particularly shown herein as printed matrix connections of this general kind are known per se, compare for example U.S. Pat. No. 3,188,423. Suffice it to say that each crosspoint of this matrix is represented by two reed capsules, each having a normally open pair of cooperating reed contacts, as best illustrated in FIG. 6B, and each serving to switch a point in the corresponding side, customarily referred to as "R" and "T," respectively, of the speech path of the telephone system. If the telephone system is of the type in which the busy or idle condition of the crosspoints is stored in a common memory of the system no circuits other than the two speech circuits just mentioned need to be switched.

From the foregoing it will be appreciated then that by closing a pair of reed capsule contacts, a unique transmission path can be established through the matrix switch. As stated earlier, in the present embodiment, the blades of the reed capsules are made of low-remanence magnetic material, such as nickel iron. The capsules are attached to the printed circuitry (not shown) in a conventional manner.

Inasmuch as the number of tabs 3 of double-sided plug portion 2 is considerably greater than the number -- in the order of 2 .times. (8 + 8) equals 32 -- required for the speech path terminations, a sufficient number of tabs 3 are available for, additionally, terminating on this plug portion, through the medium of transfer strip 17, the connections to the control windings as described in greater detail hereinafter with reference to FIGS. 1B, 4 and 5. Plug portion 2 is arranged for insertion, in a manner known per se in a corresponding (female) printed circuit connector. Thus, it will be seen that a plurality of switching matrix assemblies (FIGS. 1A, 1B) may be removably mounted in upright position and side by side in a card file for ease in maintenance and replacement and for maximum compactness.

FIG. 4 illustrates a flexible sheet 20 of insulating material to which the control windings have been applied by conventional printed circuit techniques. By way of example, a laminate with a mylar substrate which is copper clad on both sides and on which the control windings have been formed by etching, may be employed for this purpose. The winding pattern is designed for use with conventional coordinate addressing based on the coincident half-current principle. Thus, the top half 20a of the laminate as viewed in FIG. 4 contains the row windings and the bottom half 20b contains the column windings. As indicated in FIG. 4 in broken lines, the rear face of the laminate is used to link, by means of a corresponding printed circuit conductor such as 23, the end of every other individual winding element, e.g. 21, in each row to the beginning of the next adjacent individual winding element, e.g. 22, in that row; similarly, by means of the respective printed circuit conductor such as 26, the end of every other individual winding element, e.g. 24, in each column is linked, on the rear face of the sheet, to the beginning of the next adjacent individual winding element, e.g., 25, in that column. Each of the individual printed circuit winding elements or coils has only a relatively small number of turns as schematically indicated in FIG. 4. In practice the number of turns of each of these coils may be in the order of, say, 15 turns.

The two halves of laminate 20 are subsequently folded over each other along line m-n, with the magnetic plate 10, FIG. 3, sandwiched therebetween, the result being the subassembly 30 illustrated in FIG. 5. It will be understodd that because of the double-sided character of laminate 20, insulating layers or coverings, not shown, are required to insulate the conductive printing on the rear face of the laminate against the magnetic plate.

It will be noted from FIG. 4 that each row winding has been brought out by appropriate printed circuit connections, such as 21', at a terminating perforation, such as 21", at the left edge of the top half 20a of laminate 20 so that eight such terminations numbered 1 to 8, respectively, are provided, one for each row winding. The ends of the individual column windings at the bottom end of the lower half 20b of the flexible printed circuit have been similarly brought out -- by generally L-shaped printed circuit connections -- such as 25' -- at a terminating perforation such as 25" at the left edge of the bottom half 20b of laminate 20, there being eight such terminations, numbered 1' to 8' respectively, one for each column winding. As previously indicated, a transfer strip 17, FIG. 1A, is used to electrically interconnect these terminations 1 to 8 and 1' to 8' on the flexible sheet 20 with corresponding tabs 3 on the plug portion 2 of printed circuit board 1. This transfer strip 17 of insulating material which is placed flat on printed circuit board 1, has sixteen pins extending from both sides thereof, with the lower end of each pin soldered to a corresponding printed circuit conductor (not shown) on board 1 which connects this pin with the respective tab 3; and with the upper end of each pin extending through the aforementioned perforations such as 21" and 25", FIG. 4, in laminate 20 and being soldered to the corresponding terminations of row conductors such as 21' and column conductors such as 25'.

From FIG. 3 which shows the semi-hard remanentlymagnetic plate 10 used in sub-assembly 30 it will be noted that on this plate a plurality of rows of elemental "permanent" magnets of alternating polarity are initially produced in what may be termed the bias locations of the switching matrix, the rows of this array being spaced as shown. Plate 30 may be of Remendur type of material or it may be a ferrite impregnated plastic sheet in which the material has been magnetized through its thickness as shown. Alternatively, a Remendur plate may be used in which permanent magnets have been physically inserted in the spaced relationship illustrated. In the use of the plate the permanent magnetic pole generated thereon will retain the polarity shown, since in the matrix switch there are no coils in the positions corresponding to the magnetic bias positions. More specifically, from an inspection particularly of FIGS. 1A, 3 and 5, it will be appreciated that each bias location is in registry with one contact blade of a pair of cooperating blades of a corresponding reed capsule and each control location is in registry with the other blade of the pair. Given the reed capsule pattern assumed in the present embodiment, this means that a row of control locations is provided on each side of any of the four rows of bias location -- resulting, of course, in the required total of eight rows of control locations.

In operation, in order to open or close a cross-point that is, a pair of reed capsules, it is necessary to establish, by means of the control windings, a magnetic pole in the semi-hard remanently-magnetic plate in the appropriate control location. The polarity of this pole in conjunction with the polarity of the previously established (adjacent) "permanent" pole determines whether the corresponding reed capsule contacts will open or close, as explained in greater detail in conjunction with FIGS. 6A and 6B below. To establish a pole at a certain control location on the semi-hard plate, a pulse of sufficient magnitude is directed through the appropriate row and column windings which intersect each other at the desired location. By way of example, it will be noted from an inspection of FIGS. 4 and 5, if a latching pulse "A" is connected to the matrix as shown, that is, to enter at the termination of the fourth row winding and leave at the termination of the fifth column winding, the two winding elements in control location 4-5 are energized in the same sense and so as to, in effect, set up a South pole (not shown) in this control location; therefore, and inasmuch as this magnetization is of an opposite, and thus series-aiding, direction with respect to the "permanent" North pole immediately above it, the contacts of the pair of reed capsules in question will close. Moreover, because of the square-hysteresis type remanent-magnetic material of plate 10, the low-remenance blades of these two reed capsules will remain latched as long as the elemental area of the magnetic plate at control location 4-5 will retain its South polarity. In connection with the foregoing it should be understood that in FIGS. 1A, 4 and 5 the arrows drawn in full lines schematically indicate the winding direction of the printed coils on laminate 20; and that the arrows drawn in borken lines in FIG. 5 indicate the winding direction of the printed coils on the bottom (rear) section 20b of the laminate after it has been folded over line m-n, FIG. 4.

It will be noted that this operation is based on the coincident flux principle since the flux from any one coil is not sufficient to change the magnetic polarization of the plate material: only at the crosspoint where both the corresponding row winding and the corresponding column winding are energized will the magnetic polarization of the plate material at this point be changed from one state to the other -- or, for that matter, to a particular state, viz., in the case where there is originally no magnetization at the crosspoint in question.

The unlatching of a crosspoint has been indicated at control location 6-2. Thus, if an unlatching pulse "B" is applied to the matrix in a current direction where it enters at the termination of the second column winding and leaves at the termination of the sixth row winding, the two winding elements in control location 6-2 are energized in the same sense; since this magnetization is of the same direction (North) as that of the "permanent" North pole immediately above it, the magnetization of the elemental area of the magnetic plate at the control location 6-2 will be reversed (if the crosspoint had previously been in latched condition). As a result, both reed blades of each of the two capsules in question, being now polarized in the same sense, will repel each other and the contacts will open.

The pulses used herein are of a magnitude -- such as approximately 15 amperes -- sufficient to effect the switching of the semi-hard magnetic material of the plate from one polarity to the other, having regard to the relatively low number of turns used in the printed coils. The duration of these pulses, however, may be quite short, since the time required to switch the semi-hard material from one direction of polarization to the other falls within the microsecond range; 300 microseconds may be considered typical. As mentioned, the direction of the contact opening or unlatching pulses "B" is opposite to that of the contact closing or latching pulses "A". In spite of this, and notwithstanding the fact that at one end all row windings and all column windings are multiplied together at 27, the creation of undesired current paths through the array of control windings is avoided, since, in the embodiment disclosed, it is assumed that all the pulses used herein are time displaced with respect to each other. Common control apparatus producing such sets of relatively time displaced control pulses are well known in the art.

In FIGS. 6A and 6B reed capsule 4 has been shown at an enlarged scale to schematically illustrate the general flux pattern applying to the closed condition (FIG. 6A) and open condition (FIG. 6B) of the contacts of this capsule. Reed capsule 4 has an envelope, for example of glass, carrying at its lower end -- the bias location BL -- reed blade 44 having a contact portion 42 and terminal portion 43, and carrying at its upper end -- the control location CL -- reed blade 41 having a contact portion 45 and a terminal portion 46. It will be noted that in the bias location the magnetic plate is pre-polarized so as to exhibit a "permanent" South pole S on the side of the plate facing the reed capsule. In response to an operating or latching pulse traversing the row and column coils (not particularly shown in FIGS. 6A and 6B), plate 10, in control location CL, assumes a magnetic state of a direction which in this location gives rise to a North pole N' on the side of the plate facing the reed capsule. Since the polarization of the control location and that of the bias location are of opposite direction or series-aiding, a flux pattern of the general kind shown in FIG. 6A is set up and the two reeds are mutually attracted, that is, the pair of contacts closes and it ramains closed as long as the magnetization in control location CL is not reversed. In response to a release or unlatching pulse traversing the row and column coils the magnetic state of plate 10 in control location CL is reversed so that a South pole S" is set up in this location on the side of the plate facing the reed capsule. Inasmuch as, in this condition, the control location and the bias location are polarized in the same direction, a flux pattern schematically indicated in FIG. 6B results so that the two cooperating reeds are mutually repelled and the contact pair opens and remains open until the magnetic state of the plate in the control location is again reversed.

The second embodiment of the invention, depicted by FIGS. 7 through 10, employs reed capsules in which, as previously mentioned, one blade is made from permanent magnet material and is permanently polarized in a certain direction. This reed will retain its polarity regardless of the direction of flux in the adjacent location. The other blade -- which registers with the adjacent (control) location of the matrix -- is made from a switchable, that is remanently magnetic material with substantially square loop hysteresis characteristics such as Remendur. By pulsing the control windings, the polarity of the semi-hard blade can be switched directly to accomplish contact opening or closure. A magnetic plate such as plate 10 of the first embodiment is now required in the present modification.

FIG. 7 shows the details of reed capsule 50 used in the second embodiment. As shown in the drawing, mounted at one end of envelope 57 -- the left end in FIG. 7 -- is reed blade 51, of semi-hard, switchable material, which has a contact portion 52 and a terminal portion 53. The other blade 54 is made of permanently magnetic material, for example, CUNIFE as marketed by Indiana General Corporation, and it is longitudinally magnetized so that, in the assumed example, a South pole S appears at the free end of the contact portion 55 of the blade and a North pole N at the free end of its terminal portion 56. 58 is an identifying band marked on envelope 57 to insure correct reed capsule orientation during the assembly of the switching matrix.

The overall assembly of this matrix is shown in FIG. 10A in top view and FIG. 10B in side view. FIG. 8 shows the printed circuit board 60 and FIG. 9 the laminate 70 which, as best shown in FIG. 10B in this instance is sandwiched between printed circuit board 60 and the various (8 .times. 8 = 64) pairs of reed capsules such as 64, 65, FIG. 10A. In the present case it is assumed that the terminal portions such as 56, of the reed blades are connected to the printed circuit (not shown) on board 60 by means of separate pins 59 which, as indicated in FIG. 10B, extend through board 60 and laminate 70, and are soldered at one end to the printed circuit board 60 and at the other end to reed blade portions 56.

The pattern in which all of these reed capsules are mounted in holes 69 of board 60 will be readily appreciated from FIG. 8 which shows the rear of the board; as may be seen in FIGS. 9 and 10A, laminate 70 has corresponding holes 69' to allow the assembly of the reed capsules. 62, FIGS. 8 and 10A, is the plug portion of the board, on which a sufficient number of connector tabs are provided substantially as in the first embodiment described hereinabove. Again, the printed circuit conductors forming the transmission paths switched by the reed capsules, have not been shown for the sake of clarity. Also, in a manner similar to the first embodiment, a thin transfer strip 67 is mounted near the left edge of the printed circuit board as viewed in FIG. 10A, as an aid in terminating the printed row and column windings of flexible laminate 70 on corresponding ones of tabs 63 of plug portion 62.

As shown in FIG. 9, flexible plastic laminate 70 has the control windings formed thereon by printed circuit techniques, for example, by etching. In its left section 70a--which is the top section in FIG. 10A -- there are formed the row windings, and in its right section 70b -- the rear section in FIG. 10A -- the column windings, these two sections being directly folded over each other along line r-s. In the instant case each of the winding elements used consists of one straight conductor only -- as indicated by reference numeral 75 for the top element of the first column winding and by numerals 71 and 72 for the first and second row windings. The printed circuit conductors connecting column winding 1 and row winding 1 with their respective transfer strip terminations 75" and 71" have been designated as 75' and 71' respectively. At their other ends all the column windings and all row windings are joined together, for the purpose of coordinate addressing, by printed conductor 77.

The straight conductors such as 75, 71 and 72, mentioned above, are, roughly the equivalent of one quarter of a conventional coil turn. It is for this reason that in the case of the second embodiment no end-to-end connections of adjacent "coils" are required, and that accordingly laminate 70 needs only to be one-sided. On the other hand pulses of larger magnitude, for example 30 amperes, are required than in the first described implementation.

It will be appreciated from the foregoing that the operation of the switching matrix, FIGS. 7 to 10, is otherwise the same as the operation of the matrix of the first embodiment. That is, both actuation and release of any given crosspoint is accomplished by coincident energization of the corresponding row and column winding by means of time displaced pulses of a length of approximately 300 microseconds, with the release or unlatching pulses "B" being of a current direction opposite to that of the operating or latching pulses "A." As in the first example, the pulses required for the latching of crosspoint 4-5 and for unlatching the crosspoint 6-2 have been indicated (in FIG. 9).

It should be understood that the embodiments described herein are merely illustrative of the invention, and are in no sense intended to be limiting .

Claims

1. A pulse-actuated reed switching matrix of the magnetically latching type, comprising a planar printed circuit board, a coordinate array of substantially coplanar reed capsules, each including a pair of cooperating contact blades of magnetic material, said reed capsule array being supported by said printed circuit board and oriented such that the plane of said array is parallel to the principal plane of said printed circuit board and, superposed on said reed capsule array, substrate means having a coordinate array of printed circuit windings formed thereon for selectively effecting the operation and release of the reed capsules of

2. A switching matrix as claimed in claim 1, wherein said coordinate array of printed circuit windings comprises a set of column windings in one plane and a set of row windings in another, parallel plane, said sets of column and row windings between them forming a coordinate array of control locations, each registering with the location of one blade of said cooperating pair of contact blades of one or more corresponding reed

3. A switching matrix as claimed in claim 1, wherein said operating pulses are time displaced with respect to each other, and wherein said release pulses are time displaced with respect to each other and with respect to

4. A switching matrix as claimed in claim 1, wherein said operating pulses

5. A switching matrix as claimed in claim 2, wherein said column windings and said row windings are connected together at one end thereof, whereas the other ends of said column windings and said row windings are separately terminated for the selective connection of said pulses thereto.

6. A switching matrix as claimed in claim 2, wherein said one contact blade of each said reed capsule, which is provided in a corresponding control location, is of semi-hard magnetic material having substantially square hysteresis loop characteristics, and wherein the other blade of each said

7. A switching matrix as claimed in claim 6, wherein said reed capsules are mounted on a printed circuit board having terminals of said reed capsules inserted therein, and wherein the substrate means on which said column windings and said row windings are formed are sandwiched between said

8. A switching matrix as claimed in claim 1, wherein the terminals of said reed capsules are inserted in said printed circuit board, said substrate means is carried by said printed circuit board and said board at one edge thereof has a connector plug portion comprising a plurality of tabs, certain of said tabs terminating the matrix connections to said contact blades and others of said tabs terminating said other ends of said column

9. A switching matrix as claimed in claim 8, wherein said printed circuit board adjacent said edge carries a transfer strip of insulating material having terminal pins inserted therein, said pins being electrically interposed between said other ends of said column and row windings and

10. In a reed switching matrix of the magnetically latching type having a coordinate array of substantially coplanar reed capsules, each including a pair of contact blades or magnetic material, one of said blades having a magnetic bias of a predetermined direction produced thereon while the direction of magnetization of the other blade is controllable; the improvement comprising:

a flexible sheet of insulating material having two sections, one of said sections having a set of column windings and the other section a set of row windings printed thereon, said two sections when folded over each other, in projection forming a coordinate array of control locations each disposed for registry with said other blade of the corresponding reed

11. A pulse-actuated switching matrix of the magnetically latching type, comprising a coordinate array of substantially coplanar reed capsules, each including a pair of cooperating contact blades of low remanence magnetic material; superposed on said reed capsule array, substrate means having a coordinate array of printed circuit windings comprising a set of column windings in one plane and a set of row windings in another, parallel plane, said sets of column and row windings between them forming a coordinate array of control locations, each registering with the location of one blade of said cooperating pair of contact blades of one or more corresponding reed capsules; and superposed on said reed capsule array in a plane proximate thereto, a coordinate array comprising first and second interlaced sets of elemental magnetic areas, said first set of elemental magnetic areas, which are polarized in a direction normal to said plane, being provided at said control locations, said second set of elemental magnetic areas, which are prepolarized in a direction normal to said plane, being provided at bias locations registering with the locations of the other blade of said pair of cooperating contact blades of

12. A switching matrix as claimed in claim 11, wherein said coordinate array of elemental magnetic areas is formed on a plate of semi-hard magnetic meterial having substantially square hysteresis loop

13. A switching matrix as claimed in claim 12, wherein each said column winding and each said row winding comprises a plurality of individual winding elements, adjacent winding elements of at least each of said row windings being wound in mutually opposite sense, and wherein adjacent elemental magnetic areas in each row and each column of said second set of

14. A switching matrix as claimed in claim 13, wherein said reed capsules are provided in first and second pairs, each first and second pair being disposed so as to share a common bias location but have a separate control location in the adjacent rows on the two sides respectively of said bias location, the row winding elements in said two control locations being

15. A switching matrix as claimed in claim 12, wherein said reed capsules are mounted on a printed circuit board having terminals of said reed capsules inserted therein; wherein said plate of magnetic material is sandwiched between two substrates of insulating material, on one of which said column windings and on the other of which said row windings are formed; and wherein said substrates with said magnetic plate sandwiched therebetween are mounted on said printed circuit board, in spaced relation thereto, on the side of the reed capsules opposite that facing said board.

16. A switching matrix as claimed in claim 15, wherein said two substrates are two sections, respectively, of a single sheet of flexible insulating material.