US3114008A - Coordinate switch - Google Patents

Description

Dec. 10, 1963 J. PETERSEN ETAL 3,114,008

COORDINATE SWITCH Filed May 20. 1959 4 Sheets-Sheet 1 Jive 0K5 Jib 196767 6 671567 Eedzz' Jame) Werzzerj mad/ 220, Q

Z arzzer Cordzi,

1963 J. PETERSEN ETAL 3,114,008

COORDINATE SWITCH 4 Sheets-Sheet 2 Filed May 20, 1959 flverz L oni dizz yeiz J7 pfidr/m? 6022012677 @rmer jainawz 5 z erzzer Cor Z3 '3 Filed May 20, 1959 10, 1963 J. PETERSEN ETAL 3,114,008

, COORDINATE SWITCH 4 Sheets-Sheet 3 jkmwzford JZZ 219622 Pdsnfie fl a/7750i 502707 7 fi/grrzer Jemamw, Werner Cor Dec. 10, 1963 J. PETERSEN ETAL 3,114,008

COORDINATE SWITCH Filed May 20. 1959 4 Sheets-Sheet 4 Werner fle/fimwnw, Werner 6 J 5,

United States Patent r 3,114,008 CQGRDINATE SWITCH liirgen Petersen, Friedrich Summer, Werner Lehmann,

and Werner Cordt, all of Munich, Germany, assignors This invention is concerned with improvements applicable to the coordinate selector switch disclosed in copending application Serial No. 573,039, filed March 21, 1956, now Patent No. 3,053,938 and to related disclosures contained in copending applications Serial Nos. 723,788,

2 produce a stray field extending to the shunt, such stray field weakening the principal field and at the same time exerting on the contacts a force which is opposed to the force serving for the contact actuation. The fieldof the stray field prevents the undesired contact actuation, its

' operation bringing about a reduction of the effect resulting from the energization of individual coils considered apart from other coils.

now abandoned, and 726,006, now Patent Number 3,005,-

877, filed respectively March 25, 1958, and April 2, 1953.

The various objects and features of the invention will appear from the description which is rendered below with reference to the accompanying drawings.

FIG. 1 shows parts of a coordinate switch according to the copending application Serial No. 573,039, now Patent 3,053,938;

FIG. 2 represents parts of a coordinate selector switch constructed in accordance with the invention;

P16. 3 illustrates plug-in terminal means in exploded tion Serial No. 573,039, now Patent 3,053,938, as shown in FIG. 1, comprises mutually crossing column and row coils and in addition thereto holding coils which respectively embrace whole lines and rows of the switch. Contact sets are disposed at crossingpoints of the coils, the contact springs of each set carrying the magnetic flux required for the operative actuation thereof. Contacts operating according to this principle are referred to as sealed-in contacts or as protective-tube contacts. As shown in FIG. 1, there are four crossing points and, accordingly, there are four contactsets l, 2, 3, 4, each consisting in this example of a sealed-in; contact. The contact sets are embraced by column coils A and B and by row coils C and D. There are in addition two holding coils H1 and H2 which upon ener-gization hold an op eratively actuated sealed-in contact in its actuated position. It is, of course, clear that the number of crossing points of such a switch may be increased as desired.

In the operation of such a coordinate switch, the energization of a column coil and a row coil, responsive to coincident current therein, impresses upon the contact set disposed at the crossing point of these coils a sufficiently strong magnetic field to effect operative closure of the contacts. When it is desired to hold the contacts in actuated position after disconnection of the corresponding column and row coils, the particular cooperatively disposed holding coil will be energized, such coil providing the magnetic field required for holding the contacts closed. In order to reliably avoid undesired energization of a further contact set incident toenergization of another column or row coil disposed in crossing relationship with the energized holding coil, which would The present invention is concerned with a particularly advantageous construction of the iron path included in the shunt.- According tov the invention, the iron path is built up of frame plates made of magnetizable sheet material, such plates extending from the terminals of the contact springs at one end of a contact to the terminals of the contact springs at the other end of the contact, also extending in one coordinate direction of the switch, and moreover, extending for the formation of the magnetic shunt adjacent the coils in a spacing from the contacts so as to obtain a sufiicient shunt effect.

The advantage of the iron path built up in this manner resides in its particularly simple structure. The iron path may be produced in a single operation, by stamping from a sheet metal strip, with simultaneous bending to provide the desired shape, all .of which may be effected by the use of a single stamping tool. The resulting frame plates also facilitate operations in assembling a switch since the switch is substantially built up of parts extending in superposed tiers or layers.

A suitable embodiment incorporating the above noted features is obtained by trough-like formation of the securing means for the coils extending in the same coordinate direction as the frame plates, such troughs or recesses being stamped into the frame plates, and providing cutouts in the frame plates as securing means for the coils extending in the other coordinate direction, the corresponding coils being inserted by way of these cut-outs. The magnetic shun-t for the coils inserted by way of the cutouts is thereby formed by extensions. bent at right angle from the frame plates, such extensions embracing electrically connected together in the corresponding line or row. The securing means are formed by trough stamped into the frame plates.

A switch construction can in this manner be achieved which can be enlarged or extended as desired in the direction of the superposed layers, since there will be no coils extending through in such direction. This is of advantage particularly in view of the fact that switches of different size or capacity can in this way be produced in simple manner. The structural elements of the switches always remain the same.

FIG. 2 shows part of the construction according to the invention in which cutouts are provided in the frame plates for the coils extending perpendicularly thereof. The portion of the construction shown in the figure embraces the frontal part of an entire line. Referring to the basic structure of FIG. 1, this means, for example, that the column coil A, the row coils C and D and the holding coil 1 with the respectively cooperating contact sets, are involved. The coils shown inFlG. 2 are ac- Patented Dec. 10, 1963 holding coils. This results in a particular advantage which will be discussed more in detail later on. The frame plates enclose within securing means the coils extending in the same coordinate direction, in the assumed case the holding coils such as H1 and the column coils such as A, and the coils extending in the other coordinate direction, in the assumed case the row coils such as C and D. The securing or holding means for the holding coils and for the column coils consist of troughs or recesses provided in the frame plates by stamped-out portions 6. Since two mutually symmetrically constructed frame plates contain all contact sets of the cor-responding coordinate direction, two mutually oppositely positioned troughs or recesses will form channels in which the respective coils will be held.

The sheets are on both sides of the coils carried to the sealed-in contacts so as to effect the magnetic shunt action. This is upon the side of the holding coil H1 carried out so that the sheets are extended to the terminal ends 1 of the sealed-in contacts, preserving the electrical insulation formed by the insulating plate 7, and also to the protective tubes of the sealed-in contacts. In case the holding coil H1 alone is energized, the stray flux produced thereby will be conducted, in accordance with the principle of the copending application Serial No. 573,039, to the part of the frame plates lying between the involved stamped-out portions 6 and the row coils C and D, extending on the other side of the holding coil H1 to the terminal ends of the sealed-in contacts.

The =formation of the shunt for the line coil A follows the same principle; the sheet is in such case likewise car ried to the sealed-in contacts on both sides of the stamped-out portion 6 containing the column coil A. A larger intervening space is in this case however provided between the frame plate and the terminal ends; the ends of frame plates, extending on this side opposite the terminal ends, being carried straight outwardly at the level of the protective tubes of the sealed-in contacts. The ends of the frame plates are thereby disposed at a spacing corresponding to the outer dimensions of the sealedin contacts. A subsequent exchange of contact sets or of individual contacts is thereby made possible since such contacts can always be manipulated, removed from or inserted into the structure, in the direction of the line coil A.

In order to secure upon this side (right side in FIG. 2) a good magnetic circuit between the ends of the frame plates and the terminal ends of the contact springs, plugin terminal members .8 are jacked upon the terminal ends such plug-in members providing the electrical connection between the terminal ends and the soldering tabs 9 extending therefrom and also a good magnetic connection between the terminal ends and the frame plates.

A plug-in terminal assembly is shown in exploded view in PIG. 3. It comprises a holder 10 made of a suitable insulating material, an insulating plate 11 and a magnetic connecting member 12. The holder 10 secures the parts in assembled position. It is for this purpose provided with a locating pin 13 which extends through corresponding holes formed in the insulating plate 11 and the connecting member 12, the pin 13 being after assembly of the parts peened over or riveted over depending on the kind of insulating material employed. The holder 19 has grooves formed therein for receiving the terminal ends of the sealed-in contact springs and of the soldering tabs therefor. These are pressed together or connected together by soldering or spot welding, spot welding being indicated in FIG. 3. In assembled position, the terminal part 12 is separated from the terminal ends of the contact springs merely by the insulating plate 11 which may be made so thin as to produce only a small air gap which is practically without any consequence. The magnetic connection between the terminal part 12 and the terminal ends of the contact springs is in this manner established. The magnetic cond nection to the end of the frame plates is established by the tongues 14 of the terminal part 12. Slots are provided at the ends of the frame plates (see FIG. 2) in which the central resilient tongue is inserted. This central tongue engages the frame plate at the top while the two outer tongues grip the plate at the bottom, thereby providing for a clamping action. The magnetic connection results at this place from the engagement of the tongues 14 of the terminal sheet with the frame plate. FIG. 2 shows two such plug-in terminal means 8 for contact set comprising four sealed-in contact springs. ese two plug-in means can, of course, be combined in a single structural element, for example, by forming the required two holders such as lit) (FIG. 3) as a unit.

T he holding or securing means for the coils extending perpendicularly to the frame plates 5 (in FIG. 2 the row coils C and D) are formed by cutouts in the frame plates through which these coils are inserted. The magnetic shunt for these coils is thereby formed by extensions 15 bent rectangularly from the frame plates, such extensions embracing the contact sets associated with the respective coil. Extensions such as 15 in FIG. 2 are accordingly also provided at the opposite side of the contact set which is not visible in the figure. The extensions 15 are carried on both sides of the row coils C and D over a certain length of the sealed-in contacts, forming in this manner the magnetic connection to the contact springs. Upon energization, for example, of the row coil C, the field generated thereby will spread from the contacts to one of the extensions 15 in the region next 'to the coil and from there along the extension to the other side of the coil and thereupon back to the contact springs. Since the extensions 15 embrace the contact sets from both sides, there will result for all four contacts of a contact set a uniform magnetic effect.

The shunt action of the extensions 15 may be increased by inserting between the contact sets, in the region of the working air gaps thereof magnetizable inserts extending through the space between all contact sets in the coordinate direction corresponding to the direction in which the frame plates extend. Accordingly, in the embodiment illustrated in FIG. 2, the inserts extend in the direction of the holding coils and the column coils. Such an insert is indicated in this figure by numeral 16, the insert being made in the form of a flat metal strip extending along the space between all contact sets in the direction of the column coil A. The insert is at the end visible in the drawing bent angularly upwardly and outwardly, thus forming a tongue 17 projecting through a slot formed in the extension 15 of the upper frame plate. The magnetic connection between the frame plate and the insert is in this manner established and the insert is held in its assigned position. The configuration is identical on the other side of the structure.

The inserts which are made of magnetizable metal sheet eifect a closer magnetic connection between the extensions 15 and the sealed-in contacts. The magnetic action is more in detail explained in the previously noted copending application Serial No. 723,788 which is likewise to be considered in the nature of a further development on the disclosure of copending application Serial No. 573,039.

FIG. 2 also shows a metal strip 23 which acts as a shunt winding for the line coil A. This metal strip is inserted into the trough or recess formed by the portion 6 next to the column coil A. The strip is of course provided with an opening through which the sealed-in contacts can be inserted. Its overall shape accordingly corresponds generally to the shape of the column coil A. It is of course possible to insert such strips adjacent to the other coils. The action of the shunt windings formed by these metal strips effects delayed actuation and delayed restoration of the contacts.

The cutouts stamped into the frame plates 5 for re ceiving the row coils C and D naturally have more or less sharp edges unless they are rounded by a separate operation. In order to avoid damage to the row coils by such sharp edges, there are providedjackets l8 surrounding the row coils at least in part. These jackets prevent direct contact between the coils and the edges, thereby avoiding damage. The jackets 18 may, for example, be made of pressed or molded material; however, they may also be made of electrically conductive material acting as ashunt winding.

FIG. 4 is a section through the arrangement according to FIG. 2,.showing the two frontally disposed sealed-in contacts of a contact set enclosed by two frame plates 5. Elements corresponding to those shown in FIG. 2 are similarly referenced and further description ofFIG. 4 is therefore omitted.

FIG. 5 shows the basic construction of a selector switch in which the coils extending perpendicularly to the frame plates are per contact set subdivided into individual windings. The frame plates are omitted to keep the drawing lucid. The general construction corresponds to FIG. 1 and identical elements are therefore similarly referenced. As will be seen'from FIG. 5, the row coils shown in FIG. 1 at C and D are respectively subdivided into windings W1, W3 and W2, W4.

FIGS. 6 and 7 show an example of a frame plate adapted for the basic construction according to FIG. 5.

FIG. 6 illustrates a partly broken away elevational view of a layer of the selector. It comprises a frame plate 19 having three portions 20, 21', 22 forming recesses or troughs which serve for holding coils. The troughs formed by the portions 29 and 22 secure respectively a holding coil H and a line coil Z, such coils extending in parallel to the frame plate. Each contact set is surrounded by its own winding W, such windings being held in the trough formed by the. portion 21. In order to form the coordinates, the superposed windings W, that is, those which lie in successive layers, are electrically interconnected, for example in parallel or in series connection as indicated in FIG. 5. The provision of these windings W, one per contact set, avoids the necessity of forming cutouts in the frame plates which would otherwise be required for the disposal of a coil common to the contact sets.

FIG. 7 shows a section through the arrangement illustrated in FIG. 6. It will be clearly seen that the provision of the coils common to several contact sets and of the coils respectively individual to each contact set, in the troughs, results in a good magnetic shunt, since the metal sheet adjacent the troughs can be carriedclose to the sealed-in. contacts. FIG. 7 employs for similar elements the same references as FIG. 5 and further explanations are therefore omitted. The showing of FIG. 7 is limited to the basically required elements; general mounting means being for the sake of simplicity omitted. The space between the upper ends of the frame plates wand the terminal ends .of the sealed-in contacts can be filled by plug-in terminals as shown in FIGS. 2 and 3, thereby also effecting a tight magnetic connection.

FIG. 8 shows part of the construction according to the invention corresponding to FIG. 2, in which the terminal ends of the sealed-in contacts are particularly advantageously disposed. The terminal ends of the sealed-in contacts are in this embodiment embedded in a hardened responding layer of the selector switch and if so provided,

molding mass forming a block 20 from which parts of will give stability to the entire layer, which is particularly true when the ends of the forming plates are also embedded in the block. Moldable resin is particularly suitable as an embedding mass.

Each of the coordinate selector switches illustrated in FIGS. 2 to 7 has contact sets including four sealed-in contacts disposed in the outline of a square. Attention may however be called to the fact that it is evidently possible to build up the contact sets with more or fewer sealed-in contacts. It is in particularalso possible to provide in the contact sets always only one layer of sealedin contacts. It would in such case suffice to construct the magnetic shunt with only one frame plate per contact set.

The frame plates shown in the drawings have troughs formed therein serving as receptacles or recesses for securing the coils, the metal sheet on each side of the respective troughs being carried to the tubes containing the sealed-in contacts, thus producing the strongest shunt action. This is, however, not always required, since the object of the shunt is merely to prevent erroneous actuation of contact sets by reducing the operative effect of individual coils considered apart from other coils. The degree to which this reduction is required determines how close the metal sheets next to the troughs must be carried to the protective tubes. Such disposition of the metal sheets may in some cases not be required at all so that the frame plates would substantially consist of straight sheets (without troughs). The coils would in such case be secured differently, for example, by cementing. A straight configuration of the frame plates is facilitated particularly by the use of sheets of high magnetic conductivity.

Attention was previously called to the feature accord ing to which the frame plates are to extend in the coordi-.

n ate direction of the holding coils. The reason for this is as follows: I

The ends of the frame plates facing the terminal ends of the sealed-in contacts form a magnetic connection of neighboring contact sets. This magnetic connection is not operative upon energization of the hoiding coils when the frame plates extend parallel to the holding coils, since all contact sets which are magnetically interconnected by way of the ends of the frame plates, are simultaneously energized. It would be otherwise if the frame plates would extend perpendicularly to the holding coils. In such case, upon energization of a holding coil, contact sets neighboring on such holding coil, namely, those not embraced by the corresponding holding coil, would receive opposing energization by way of the ends of the frame plates, which can under some circumstances result in erroneous actuation. Details concerning this condition appear in the previously mentioned copending application Serial No. 726,006 which is likewise to be considered an improvement on or further development of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.

We claim:

1. A coordinate selector switch having sets of sealed-in contacts forming swtiching elements disposed in superposed layers and forming coordinate columns and rows and having column and row coil means operatively disposed in mutually crossing coordinate directions, and having in addition thereto holding coils extending respectively over aligned contact sets in one coordinate direction, said contact sets being respectively disposed at effective crossing points of said column and row coil means,

each contact set including sealed-in contact springs, contained within protective tube means with terminal ends of the corresponding contact springs extending from said tube means, operable in response to coincident current in the column and row coil means at the associated crossing point, and further having for each layer of said contact sets magnetic shunt means containing an iron path, said iron path comprising frame plates made of magnetizable metal sheet, each frame plate extending along one coordinate direction of the selector switch and, with respect to the corresponding layer, from a point near the terminal ends of the contact springs at one end of said sealed-in contacts to a point near terminal ends of said contract springs at the other end thereof and overlying the entire corresponding layer, parts of said frame plates being deformed out of the plane of other parts thereof and disposed adjacent said coils, extending for the formation of said magnetic shunt at a spacing from said contact sets to produce a suflicient shunt effect to prevent undesired operation of contact sets other than those at the intersection of column and row coil means actuated in response to the passage of coincident current therethrough.

2. A coordinate selector switch having sets of sealed-in contacts forming switching elements disposed in superposed layers and forming coordinate columns and rows and having column and row coil means operatively disposed in mutually crossing coordinate directions, and having in addition thereto holding coils extending respectively over aligned contact sets in one coordinate direction, said contact sets being respectively disposed at effective crossing points of said column and row coil means, each contact setincluding sealed-in contact springs contained within protective tube means with terminal ends of the corresponding contact springs extending from said tube means, and further having for each layer of said contact sets magnetic shunt means containing an iron path, said iron path comprising frame plates made of magnetizable metal sheet, said frame plates extending along one coordinate direction of the selector switch and, with respect to the corresponding layer, from a point near the terminal ends of the contact springs thereof at one end of said sealed-in contacts to a point near the terminal ends of said contact springs at the other end and overlying the entire corresponding layer, parts of said frame plates disposed adjacent said coils extending for the formation of said magnetic shunt at a spacing from said contact sets to produce a sufiicient shunt effect to prevent undesired operation of contact sets other than those at the intersection of an actuated line coil and an actuated row coil, said frame plates being respectively provided with recesses formed therein for holding those of said coils which extend in the same coordinate direction as the frame plates and with cutouts formed thereon for holding those of said coils which extend in the other coordinate direction, said latter coils being inserted in the respective cutouts, extensions being bent at right angle from said frame plates adjacent said latter coils and forming the magnetic shunt therefor, said extensions respectively embracing the contact sets cooperatively associated with the respective coil.

3. A coordinate switch according to claim 1, wherein those of said coils which extend in a coordinate direction perpendicularly to said frame plates are subdivided into individual windings, one for each contact set, said windings being electrically interconnected in the respective coordinate to which they belong.

4. A coordinate selector switch having sets of sealed-in contacts forming switching elements disposed in superposed layers and forming coordinate columns and rows and having column and row coil means operatively disposed in mutually crossing line coordinate directions, and having in addition thereto holding coils extending respectively over aligned contact sets in one coordinate direction, said contact sets being respectively disposed at effective crossing points of said column and row coils,

each contact set including sealed-in contact springs contamed within protective tube means with terminal ends of the corresponding contact springs extending from said tube means, and further having for each layer of said contact sets magnetic shunt means containing an iron path, said iron path comprising two frame plates made of magnetizable metal sheet, of symmetrical configuration containing all contact sets in the respective layer extending in the coordinate direction of such frame plates, the latter extending along one coordinate direction of the selector switch and, with respect to the corresponding layer, from a point near the terminal ends of the contact springs at one end of said sealed-in contacts to a point near the terminal ends of said contact springs at the other end thereof and overlying the entire corresponding layer, parts of said frame plates disposed adjacent said coils extending for the formation of said magnetic shunt at a spacing from said contact sets to produce a sufficient shunt effect-to prevent undesired operation of contact sets other than those at the intersection of an actuated line coil and an actuated row coil.

5. A coordinate switch according to claim 1, wherein the ends of said frame plates at one terminal'end of the contact springs in the corresponding layer extend along straight lines at levels substantially coinciding with the tube means of the corresponding sealed-in contact sets to form a space along which said sealed-in contact sets may be manipulated.

6. A coordinate switch according to claim 5, further comprising plug-in terminal means for cooperation with the terminal ends of said contact springs, said plug-in terminal means effecting a low magnetic impedance between said terminal ends and said frame plates and further respectively effecting an electrical connection extending to soldering tabs projecting therefrom and a magnetic connection between said terminal ends and said frame plates. V

7. A coordinate switch according to claim 1, wherein said frame plates extend in the coordinate direction of the holding coils.

8. A coordinate switch according to claim 1, further comprising metal strip means disposed between said plates adjacent to some of said coils, said strip means having cutouts formed therein for the insertion of sealed-in contacts and functioning as shunt winding.

9. A coordinate switch according to claim 1, further comprising magnetizable insert means disposed between individual layers at the region of the working air gaps of the corresponding contacts, said insert means extending over the entire coordinate in parallel to said frame plates and being magnetically connected at its ends to the extensions adjacent each end of a cooperable frame plate.

10. A coordinate switch according to claim 1, wherein the terminal ends of said sealed-in contact springs which are disposed along a coordinate in the direction of the frame plates are embedded in a hardenable molding mass, portions of said terminal ends forming soldering tabs extending from said mass, said mass absorbing stresses to which said soldering tabs are subjected.

References Cited in the file of this patent UNITED STATES PATENTS 2,187,115 Ellwood Jan. 16, 1940 2,245,391 Dickten June 10, 1941 2,289,830 Ellwood July 14, 1942 2,324,623 Hickman July 20, 1943 2,331,514 Stibitz Oct. 12, 1943 2,332,338 Peek Oct. 19, 1943 2,397,123 Brown Mar. 25, 1946- 2,836,676 Wirth May 27, 1958 2,935,655 Edgarton May 3, 1960 3,005,877 Nitsch Oct. 24, 1961 3,053,938 Nitsch Sept. 11, 1962 FOREIGN PATENTS 551,676 Italy Nov. 22, 1956

Claims (1)

1. A COORDINATE SELECTOR SWITCH HAVING SETS OF SEALED-IN CONTACTS FORMING SWITCHING ELEMENTS DISPOSED IN SUPERPOSED LAYERS AND FORMING COORDINATE COLUMNS AND ROWS AND HAVING COLUMN AND ROW COIL MEANS OPERATIVELY DISPOSED IN MUTUALLY CROSSING COORDINATE DIRECTIONS, AND HAVING IN ADDITION THERETO HOLDING COILS EXTENDING RESPECTIVELY OVER ALIGNED CONTACT SETS IN ONE COORDINATE DIRECTION, SAID CONTACT SETS BEING RESPECTIVELY DISPOSED AT EFFECTIVE CROSSING POINTS OF SAID COLUMN AND ROW COIL MEANS, EACH CONTACT SET INCLUDING SEALED-IN CONTACT SPRINGS, CONTAINED WITHIN PROTECTIVE TUBE MEANS WITH TERMINAL ENDS OF THE CORRESPONDING CONTACT SPRINGS EXTENDING FROM SAID TUBE MEANS, OPERABLE IN RESPONSE TO COINCIDENT CURRENT IN THE COLUMN AND ROW COIL MEANS AT THE ASSOCIATED CROSSING POINT, AND FURTHER HAVING FOR EACH LAYER OF SAID CONTACT SETS MAGNETIC SHUNT MEANS CONTAINING AN IRON PATH, SAID IRON PATH COMPRISING FRAME PLATES MADE OF MAGNETIZABLE METAL SHEET, EACH FRAME PLATE EXTENDING ALONG ONE COORDINATE DIRECTION OF THE SELECTOR SWITCH AND, WITH RESPECT TO THE CORRESPONDING LAYER, FROM A POINT NEAR THE TERMINAL ENDS OF THE CONTACT SPRINGS AT ONE END OF SAID SEALED-IN CONTACTS TO A POINT NEAR TERMINAL ENDS OF SAID CONTACT SPRINGS AT THE OTHER END THEREOF AND OVERLYING THE ENTIRE CORRESPONDING LAYER, PARTS OF SAID FRAME PLATES BEING DEFORMED OUT OF THE PLANE OF OTHER PARTS THEREOF AND DISPOSED ADJACENT SAID COILS, EXTENDING FOR THE FORMATION OF SAID MAGNETIC SHUNT AT A SPACING FROM SAID CONTACT SETS TO PRODUCE A SUFFICIENT SHUNT EFFECT TO PREVENT UNDESIRED OPERATION OF CONTACT SETS OTHER THAN THOSE AT THE INTERSECTION OF COLUMN AND ROW COIL MEANS ACTUATED IN RESPONSE TO THE PASSAGE OF COINCIDENT CURRENT THERETHROUGH.

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