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Publication numberUS3886335 A
Publication typeGrant
Publication dateMay 27, 1975
Filing dateJan 26, 1973
Priority dateJan 26, 1973
Publication numberUS 3886335 A, US 3886335A, US-A-3886335, US3886335 A, US3886335A
InventorsHendricks John E
Original AssigneeInd Electronics Engineers Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Collated cable matrix switch
US 3886335 A
Abstract
In a matrix of switches disposed in rows and columns, a plurality of first discrete conductors are deposited on the surface of a first backing member to extend in a first direction and a plurality of second discrete conductors are deposited on the surface of a second backing member to extend in a second direction. Dielectric spacing means is disposed between the first and second backing members to maintain the first and second conductors in a normally spaced relationship. The spacing means defines a plurality of openings each extending between an associated pair of the first and second conductors which define one of the switches. By pressing the associated pair of conductors into relative engagement through the associated opening in the spacing means, a signal on the associated first conductor is switched to the associated second conductor.
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Description  (OCR text may contain errors)

United States Patent 1 1 Hendricks COLLATED CABLE MATRIX SWITCH John E. Hendricks, Encino, Calif.

[73] Assignee: Industrial Electronics Engineers,

Inc., Van Nuys, Calif.

[22] Filed: Jan. 26, 1973 [21] Appl. No.: 327,152

[75] inventor:

[52] US. Cl 200/1 R; 200/5 R; 200/5 A; 200/159 B; 340/365 R [51] Int. Cl. H0lh 13/70; G086 9/00 [56] References Cited UNITED STATES PATENTS 3,193,607 7/1965 Anderson 200/5 RX 3,308,253 3/1967 Kraltinowski... 200/159 B UX 3,496,311 2/1970 Holzer 200/5 R 3,502,824 3/1970 Bonacquisti 200/5 R X 3,531,603 9/1970 Ashman 200/11 D 3,584,162 6/1971 Krakinowski 200/5 A 3,627,927 12/1971 Schmitz et a1 200/159 B UX 3,668,337 6/1972 Sinclair 200/159 BX 3,743,797 7/1973 Huffman 200/5 RX Primary Examiner-James R. Scott Attorney, Agent, or FirmEllsworth R. Roston [57] ABSTRACT in a matrix of switches disposed in rows and columns,

1 51 May 27, 1975 a plurality of first discrete conductors are deposited on the surface of a first backing member to extend in a first direction and a plurality of second discrete conductors are deposited on the surface of a second backing member to extend in a second direction. Dielectric spacing means is disposed between the first and second backing members to maintain the first and second conductors in a normally spaced relationship. The spacing means defines a plurality of openings each extending between an associated pair of the first and second conductors which define one of the switches. By pressing the associated pair of conductors into relative engagement through the associated opening in the spacing means, a signal on the associated first conductor is switched to the associated second conductor.

The second conductors can extend through a pair of the switches and can be bisected therebetween to increase the number of discrete switches in the matrix without increasing the number of conductors. A bar clamp provides an interface between the switches in the matrix and the electronics associated with the controlled operations.

A method for making the matrix of switches includes the steps of providing a spool for each of the backing members, the conductors, and the spacing means, and guiding the conductors and the spacing means in a spaced relationship onto the backing member. This process can be performed at high speed with inexpensive materials to significantly reduce the cpst of manufacturing the matrix of switches.

27 Claims, 24 Drawing Figures PATENTEUMAY 27 1975 SHEET PATENTEDMAY 27 I975 SHEET A F 8 6 C A p I Pmmaumev ms 3.886 335 SHEET 7 a? Y A z a a2, AJ FY PATENTED MAY 27 ms SHEET VII/J n wnnu w l 1 COLLATED CABLE MATRIX SWITCH BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to matrix switches which are particularly adaptable to alphanumeric keyboards, and a method for manufacturing the matrix switches at a relatively low price per switch.

2. Description of Prior Art It has been desirable to provide an alphanumeric keyboard, such as those commonly used with typewriters, adding machines, and computer input terminals, with a matrix switch including a separate switch for each of the keys on the alpha-numeric keyboard. The matrix of switches has permitted electrical control of the particular operation with a resulting increase in speed and efficiency.

The switching matrices of the prior art have been manufactured by elaborate and time-consuming processes. This has made electrically actuated control of the particular operation prohibitively expensive for some applications. For example, the switching matrices of the prior art have relied upon electro-chemical processes, such as metal deposition and etching processes, to provide circuit conductors and switch contact surfaces. These processes have included numerous expensive steps so that the resulting switching matrices have had a relatively high cost per switch.

Copending application Ser. No. l63,399, and now abandoned assigned of record to the assignee of record of the present application, discloses and claims a flexible switch having a first conductor disposed on the surface of the first backing member and a second conductor disposed on the surface of a second backing member. A spacing member which normally separates the first and second conductors is provided with an opening extending therebetween so that the first and second conductors can be moved into relative engagement through the opening. This enables the signal on the first conductor to be switched to the second conductor. The backing members and the spacing members have been formed from translucent materials so that the switch can be backlighted to illuminate indicia on the switch.

Also included in the prior art are collated cables which typically are used to interconnect remote elec tronic assemblies. The collated cables are typically manufactured by providing two spools of a first and second backing material and a spool of wire for each of the conductors desired in the cable. These wires can be fed across guide means so that the conductors are sandwiched between the first and second backing members in an electrically insulated relationship to one another. The backing members can be bonded together by heat and pressure to hermetically seal the structure. This process for manufacturing collated cable can run at speeds up to 40 ft. per minute and at costs signit" cantly less than the etching and deposition processes.

SUMMARY OF THE INVENTION The low cost process for manufacturing collated cable can provide a backing member having a plurality of electrically discrete conductors disposed thereon to extend in a first direction. In a similar manner, a second backing member can be provided and second electrically discrete conductors disposed thereon to extend in a second direction transverse to the first direction. The first and second conductors can be maintained in a normally spaced relationship by a dielectric spacing means disposed in contiguous relationship with the first and second backing members. The dielectric spacing means can be provided with a plurality of openings each extending between an associated pair of the first and second conductors. The openings will enable each of the associated first and second conductors to be moved into relative engagement through the associated opening to switch a signal from the associated first conductor to the associated second conductor. In this manner a switching matrix can be provided with a switch at the intersection of each of the first conductors and each of the second conductors.

The switches in the matrix can be disposed to accommodate a particular alphanumeric keyboard so that each of the keys on the keyboard can force one of the first conductors into engagement with the associated second conductor. The number of switches per conductor can be increased by extending the second conductors through a pair of the switches and bisecting the second conductor between the switches. In this manner, two discrete switches can be defined at the intersection of two first conductors and a single second conductor.

The process for manufacturing collated cables can be used advantageously to assemble the backing members and the associated conductors. Since this major step in the process of forming the matrix switch can be performed at a high rate of speed, the resultant matrix switch can be manufactured at a relatively low cost. Furthermore, the collated cables can be disposed on translucent backing members so that the individual switches can be backlighted to illuminate the indicia of the keyboard. The provision of low-cost switching matrices will enable the high speed and efficiency of elec trically controlled operations to be economically available for a significant number of applications.

The dielectric spacing means can have a generally planar configuration with a plurality of apertures therein. Alternatively, the spacing means can comprise a plurality of longitudinal members extending in one of the first and second directions and cooperating with each other to define the openings. These longitudinal spacing members can be wound on spools and guided onto the first backing member simultaneously with the first conductors. Thus, the high-speed collating process can provide the spacing means as well as the conductors.

These and other features and advantages of the invention will become more apparent with a detailed description of the invention in conjunction with the associated drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view partially in phantom of an adding machine including a switching matrix;

FIG. 2 is an assembled view of the switching matrix shown in FIG. 1;

FIG. 3 is a perspective view of an apparatus which can be used to manufacture the switching matrix;

FIG. 3A is a cross-sectional view of a portion of the switching matrix taken on line 3a-3a of FIG. 3;

FIG. 4 is a cross-sectional view of the switching matrix taken on line 4-4 of FIG. 2;

FIG. 5 is a plan view of the keyboard of a standard typewriter;

FIG. 5A is an embodiment of a switching matrix which can be used in conjunction with the typewriter keyboard shown in FIG. 5;

FIG. 5B is a further embodiment of a matrix switch which can be used in conjunction with the keyboard shown in FIG. 5'.

FIG. 6 is a plan view of a standard adding machine keyboard;

FIG. 6A is an embodiment of a switching matrix which can be used in conjunction with the keyboard shown in FIG. 6;

FIG. 7 is one embodiment of a switching matrix which can be used with a keyboard having keys spaced in symmetrical rows and columns;

FIG. 7A is an additional embodiment of a matrix switch which can be used with a keyboard having keys spaced in symmetrical rows and columns;

FIG. 7B is a further embodiment of a switching matrix which can be used with a keyboard having keys spaced in symmetrical rows and columns;

FIG. 8 is a front elevational view of a bar clamp for terminating a matrix switch;

FIG. 9 is a cross-sectional view of the bar clamp taken on line 99 of FIG. 8;

FIG. 10 is a plan view of the bar clamp for terminating the matrix switch on a printed circuit board;

FIG. 11 is a cross-sectional view of the bar clamp taken on line 1111 of FIG. 10.

FIG. 12 is a plan view of a further embodiment of the matrix switch used in conjunction with an adding ma chine keyboard;

FIG. 13 is a cross-sectional view of the matrix switch taken on line 1313 of FIG. 12.

FIG. 14 is a plan view of an additional embodiment of the matrix switch used in conjunction with a typewriter keyboard;

FIG. 15 is a plan view of an additional embodiment of the matrix switch including longitudinal spacing members;

FIG. 16 is a cross-sectional view of the matrix switch taken on line 16l6 of FIG. 15;

FIG. 17 is a plan view of still a further embodiment of the matrix switch including the longitudinal spacing members; and

FIG. 18 is a cross-sectional view of the matrix switch taken on line 18-18 of FIG. 17.

DESCRIPTION OF PREFERRED EMBODIMENT An adding machine is shown generally in FIG. 1 and designated by the reference numeral 11. The adding machine 11 has a keyboard 13 including a plurality of keys ]5 arranged in rows and columns. By selectively operating the keys 15, the operation of the adding machine 11 can be controlled to provide a desired output which is displayed for example, on a display screen 17.

It is often desirable that the keys 15 on the keyboard 13 respectively actuate an individual electrical switch in order to permit electrical control of the operation. Electrical control is particularly desirable since it significantly increases the speed and accuracy with which the operation can be performed.

Electrical control can be accomplished by means of a switching matrix such as that shown generally at 19. The switching matrix 19, which typically includes a switch 20 for each of the keys 15, preferably is disposed in proximity to the keyboard 13 so that a slight pressure on a particular one of the keys 15 will actuate the associated switch 20.

In the preferred embodiment, the switching matrix 19 includes a plurality of first electrically discrete conductors 21 extending in a first direction, and a plurality of second electrically discrete conductors 23 which may extend in a second direction transverse to the first direction. A bar clamp 25 can provide means for individually engaging the second conductors 23 to provide an interface between the switches 20 and any electronics (not shown) associated with the controlled operation.

It will be apparent to those skilled in the art that the adding machine 11 is merely representative of many operations wherein the benefits of electrical control can be achieved by means of the switching matrix 19. For example, it will be obvious that the switching matrix 19 can be advantageously used with other alphanumeric keyboards, such as those associated with typewriters and computer input terminals. Furthermore, although the adding machine 11 is illustrated with a keyboard 13 wherein the keys 15 are disposed in symmetrically spaced rows and columns, the concepts of the invention can be embodied to accommodate nonuniform keyboards.

The switches 20 forming the switching matrix 19 can be of the type disclosed and claimed in copending application Ser. No. 163,399 and assigned of record to the assignee of record of the present application. Thus, with reference to FIG. 2, it will be noted that the switching matrix 19 can include a first backing member 27 defined by an inner surface 31 and an outer surface 33, and a second backing member 29 defined by an inner surface 35 and an outer surface 37. The first conductors 21 are preferably aligned on the inner surface 31 of the backing member 27 so that they are at least partially exposed in an electrically insulated relationship to one another. For example, the first conductors 21 can be adhered to the inner surface 31 so that they extend substantially parallel to one another in a first direction. Similarly, the second conductors 23 can be adhered to the inner surface 35 so that they are exposed in an electrically insulated relationship to one another, and generally extend in a second direction different than the first direction.

The first and second backing members 27 and 29, respectively. can be made from a suitable transparent or translucent material such as the polyester designated by the tradename Mylar and manufactured by the Du- Pont Corporation. This material is particularly desirable since it is highly resistant to solvents which may be advantageously used to clean the conductors 21 and 23. The thickness of the backing members 27 and 29 may range from 0.003 to 0.015 inches with a thickness. such as 0.005 inches preferred.

Dielectric spacing means can be sandwiched between the inner surfaces 31 and 35 of the first and second backing members 27 and 29, respectively. to maintain the conductors 21 and 23 in a normally spaced relationship. In one preferred embodiment, the spacing means comprises a spacing member 39 having a generally planar configuration and portions thereof defining a plurality of apertures 41. Each of the apertures 41 typically circumscribes an imaginary line, such as the dotted line 43 which extends between an associated one of the first conductors 21 and an associated one of the second conductors 23. Preferably. the dotted line 43 is the shortest line which connects the associated pair of the first and second conductors 21 and 23, in which case it is substantially perpendicular to the first and second backing members 27 and 29, respectively.

The spacing member 39 can be formed from any suit able dielectric material to maintain the first conductors in a normally electrically insulated relationship with respect to the second conductors 23. ln a preferred embodiment, the spacing member is formed from the polytetrafluoroethylene material marketed by DuPont under the tradename Teflon. It is within the skill of those in the art to form the spacing member 39 of other dielectric materials which may provide additional advantages under some circumstances. For example, a translucent material, such as Mylar, can be advantageously used for the planar spacing member 39 if it is desired to backlight the switches of the switching matrix 19.

The first and second conductors 21 and 23, respectively, may have a circular cross section with a diameter as small as 0.002 inches or as large as 0.020 inches. However, in the preferred embodiment, the conductors 21 and 23 are rectangular in cross section having a thickness such as 0.003 inches and a width such as 0.0l5 inches. The conductors 21 and 23 can include a suitable material, such as copper or aluminum, having a high electrical conductivity and they may be plated with a material, such as gold or rhodium, to enhance the switching characteristics of the switches 20. To minimize the plating area, rectangular cross-sectional dimensions for the conductors 21 and 23 are preferably less than 0.005 and 0.030 inches.

In an embodiment where the first and second conductors 21 and 23, respectively, have a width of 0.125 inches, the apertures 41 in the spacing member 39 may be provided with a diameter such as 0.25 inches. These dimensions have been particularly desirable for maintaining the associated first and second conductors 21 and 23 in a normally spaced relationship while enabling them to be pressed into relative engagement through the associated aperture 41. It is this relative engagement of the associated first and second conductors 21 and 23 which provides the switching characteristics for an individual one of the switches 20 in the switching matrix 19.

This preferred operation of the switching matrix 19 can be more easily understood with reference to FIG. 4 wherein one of the first conductors 21 is illustrated to extend in a first direction across the page of the drawings and some of the second conductors 23 are illustrated to extend in a second direction into the page of the drawings. The apertures 41 are defined in the dielectric spacing member 39 between the associated first and second conductors 21 and 23 to extend coaxially with the dotted lines 43. In this embodiment, the keys 15 are individually disposed for movement along one of the dotted lines 43 to engage the outer surface 33 of the first backing member 27, and to force the associated first conductors 21 through the associated aperture 41 to electrically engage the associated second conductor 23. It can be appreciated that by operation of the keys 15, the signal present on the associated first conductors 21 can be switched to the associated second conductors 23 so that the signals present on the second conductors 23 can activate the electronics (not shown) of the operation. In this manner the selective operation of the keys 15 can provide electrical control of the operation, such as the adding machine 11.

In the preferred embodiment, a relatively rigid supporting member 44 is disposed to engage the outer surface 37 of the second backing member 29 to provide support for the switching matrix 19 so that the second conductors 23 can maintain a substantially fixed position. It will be appreciated by those skilled in the art that the second conductors 23 can be moved to engage relatively stationary first conductors, or alternatively, the associated first and second conductors 21 and 23, respectively, can be simultaneously moved into engagement through the associated aperture 41.

Referring now to FIGS. 15 and 16, it will be noted that the first conductors 21 and the second conductors 23 can extend in substantially the same direction. In fact, a particular pair of the first and second conductors 21 and 23, respectively, which form a single switch 20, can be aligned in a plane substantially perpendicular to the plane of the matrix switch 19, i.e., the plane of the page. In such an embodiment, the pressing of one of the first conductors 21 substantially anywhere along the length thereof will move the pressed conductor 21 into electrical contact with the associated second conductor 23.

Although the first and second conductors 21 and 23, respectively, can have any cross-sectional configuration, it may be desirable that they have rectangular cross sectional configurations to maximize the area of contact at a particular point of contact. It may be further desirable that the second conductors 23 have a greater width than the first conductors 21 in order to facilitate their alignment during the construction of the switch.

As best illustrated in FIG. 16, the spacing means of the matrix switch 19 can include a plurality of longitudinal spacing members 39' which typically extend in the same direction as the first conductors 21 and which define an opening 41' in proximity to each of the switches 20. Although the spacing members 39' can have any cross-sectional configuration, their dimension between the first and second backing members 27 and 29, respectively, should be sufficient to provide the desired spacing between the first and second conductors 21 and 23, respectively. Also, the distance between the longitudinal spacing members 39' and the adjacent switches 20 should be sufficient to enable the conductors 21 and 23 to be moved into electrical contact through the openings 41 in a preferred embodiment which includes polyester backing members 27 and 29 having a thickness of 0.004 inches, the conductors 21 and 23 have a width of 0.030 inches, and a thickness of 0.003 inches. In this embodiment the longitudinal spacing members 39 have a generally circular cross section providing a dimension between the first and second backing members 27 and 29, respectively, of approximately 0.009 inches. This provides a desired spacing of 0.003 inches between the associated first and second conductors 21 and 23, respectively. An adjacent pair of the spacing members 39 can be disposed equidistant from the associated pair of conductors 21 and 23 and spaced from each other a distance within the preferred range of 0.100 inches to 0.250 inches.

It will be noted that if the switches 20 are sufficiently close, as at the left side of FIG. 15, they can be alternated with the spacing members 39 to maintain the desired spacing between the first and second conductors 21 and 23 in the switches 20. However. if the switches 20 are spaced a significant distance, as at the right side of FIG. 15, it may be desirable to provide a spacing member 39' on each side of an associated switch 20. In the latter case, there would typically be two spacing members 39' between an adjacent pair of the switches 20.

A further embodiment of the matrix switch 19 can be provided in accordance with FIGS. 17 and 18 wherein the longitudinal spacing members 39' extend in a common direction with the first conductors 21 but intersect the second conductors 23. The switches 20 are defined at the points of intersection between the first and second conductors 21 and 23, respectively. It will be apparent that in such an embodiment the adjacent switches 20, which are associated with a particular one of the first conductors 21, may not be separated by any spacing member 39'. Therefore, it may be desirable to separate the second conductors 23 a distance sufficient to insure that the activation of a single switch 20 does not also activate the adjacent switch 20, which is associated with the same first conductor 21. Since the adjacent switches 20 associated with a particular one of the second conductors 23 will typically be separated by one of the spacing members 39', the first conductors 21 can be provided with any suitable spacing.

In this embodiment wherein the first and second conductors 21 and 23, respectively, are transverse to each other, the spacing members 39' are generally supported by the second conductors 23. Thus, the crosssectional thickness of the spacing members 39' can be substantially equal to the thickness of the first conductors 21 plus the desired spacing distance between the first and second conductors 21 and 23, respectively.

Since the longitudinal spacing members 39' do not directly contact both the first conductors 21 and the second conductors 23, their dielectric characteristics may not be as important as those of the planar spacing member 39. However, in the preferred embodiment, the longitudinal spacing members 39' are formed from polyester filaments which have relatively high electrical insulating properties.

The embodiments of the matrix switch 19, which include the longitudinal spacing members 39', are particularly advantageous since they eliminate the expense of a separate planar spacing member 39 and also the cost of a tool which would typically be used to punch the apertures 41 in the spacing member 39. The embodiments of FIGS. through 18 are also desirable since they significantly reduce the quality control problems associated with providing apertures 41 which are free of burrs. In some cases, these burrs can increase the operating force of an associated switch 20.

In a preferred process, the first conductors 21 can be disposed on the inner surface 31 of the first backing member 27 are illustrated in FIG. 3. The first backing member 27 can be disposed on a roll 10 and fed between a pair of rollers shown generally at 12. An adhesive container 14 can be disposed between the roll 10 and the rollers 12 to deposit a suitable bonding agent 22 on the inner surface 31 of the first backing member 27. In a preferred method, the first backing member 27 is purchased with a temperature-sensitive adhesive precoated thereon. A typical commercial product of this type is manufactured by Circuit Materials Company and designated as CMC-153 polyester adhesive.

The first conductors 21 can be provided on'the respective spools 16 to engage a guide roller 18 and to pass between the rollers 12 in contiguous relationship with the backing member 27. The guide roller 18 can be of the type including a plurality of circumferential grooves 20 axially spaced on the surface of the guide roller 18. Each of the first conductors 21 can be threaded through one of the grooves 20 so that the first conductors 21 are maintained in a spaced relationship, such as a parallel relationship, as they pass between the rollers 12 to engage the adhesive 22 on the first backing member 27. The rollers 12 exert a pressure on the first conductors 21 and the first backing member 27 to provide them with a fixed relationship.

The bonding agent 22 can be a curable adhesive such as that marketed by General Mills Chemical Company under the tradename VERSALON. Such an adhesive can be partially cured prior to engaging the first conductors 21 and fully cured after the first conductors 21 have been deposited on the first backing member 27. The rollers 12 can be heated to aid in the curing of the adhesive 22. The above described process, which can be used to collate not only the first conductors 21 but also the second conductors 23, is particularly advantageous since the conductors can be collated at rates of up to 40 feet per minute. Thus, major steps in the for mation of the matrix switch 19 can be preformed at a high speed and a relatively low cost.

This preferred method provides even further advantages for those embodiments of the matrix switch 19 which include the longitudinal spacing members 39. For example, the spools 16 containing the conductors 21 can be alternated with spools 16' containing the longitudinal filaments 39. Then the filaments 39' can be guided through the corresponding grooves 26 so that the conductors 21 and the filaments 39' are simultaneously and automatically deposited on the backing member 27. The resulting combination is shown in cross section in FlG. 3a.

This preferred method will offer an even greater cost reduction for those particular embodiments including the spacing members 39' since a separate member 39 need not be provided, punched, and aligned. It is also apparent that the embodiments including the longitudinal spacing members 39' pennit a greater flexibility in design. Thus, the cost of collating a different cable including the spacing members 39' is significantly less than the cost of providing different tooling to punch the apertures 41 in the planar spacing member 39.

The concepts of the switching matrix 19 can be embodied to accommodate the patterns of many different keyboards. 1n the following detailed description of some of these embodiments, elements which have characteristics and functions similar to the elements in preceding embodiments will be provided with similar reference numerals followed by a lower case letter corresponding to the particular embodiment. The lower case letters will be chosen so that consecutive letters correspond to consecutive embodiments. For example, a matrix switch 19 can be embodied to accommodate a conventional typewriter having a keyboard 13a, such as that shown generally in FIG. 5. It will be noted that the keys 15a of the keyboard 13a extend in a plurality of rows 45 and a plurality of columns 47 having a first angular relationship with the rows 45.

A matrix switch 191:, shown in FIG. 5A, can be used with the keyboard 13a of a standard typewriter. Preferably each of the switches 20a is disposed to be operated when an associated key 15a (FIG. is depressed. For example, the switches 20a can be disposed beneath the keys a so that the switches 200 are also arranged in the rows 45a and the columns 47a. To accommodate such a keyboard, the first conductors 21a can extend in a first direction, such as the direction of the rows 45a, and the second conductors 23a can extend in a second direction different than the first direction. This will provide the second conductors 23 with a second angular relationship with respect to the rows 450. In this particular embodiment, each of the first conductors 21 is associated with an entire row 45a of the keys 150 while each of the second conductors 23a is associated with only one of the rows 45a. This provides each of the switches a with discrete characteristics so that the operation of one of the keys 15a activates only one of the switches 20a.

A signal, such as that provided by a source of operating potential 42, can be introduced to each of the first conductors 21a so that the operation of an individual switch 20a in the matrix 19a will switch the operating potential 42 to the associated one of the second conductors 23a. One method of introducing the operating potential 42 to the first conductors 21a is to include among the second conductors 230 a particular conductor 49 which preferably does not extend through any of the switches 20a. The particular conductor 49 can be soldered or welded to each of the first conductors 21a so that a signal introduced to one of the first conductors 21a is introduced to all of the first conductors 21a. The welds or solder joints can be made through holes (not shown but similar to the apertures 41a) in the spacing member 390 or, alternatively, the spacing member 390 can be cut short so that the first conductors 21a are exposed to the particular second conductor. Of course, signals can also be introduced to the first conductors 21 by a bar clamp similar to the bar clamp 25 terminating the second conductors 23.

The second backing member 29a can include a first edge 48 and a second edge 50 between which the second conductors 23a extend. At least one of the first and second edges- 48 and 50, respectively, can extend a distance such as 0.25 inches beyond the first backing member 27 and the dielectric spacer 390 so that the second conductors 230 are exposed on the extended edge. Each of the extended edges 48 and 50 can register with one of the bar clamps 250 (FIG. 1) to provide an interface between the second conductors 23a and the electronics of the typewriter (not shown). In the preferred embodiment only the first edge 48 is extended; however, the second edge 50 can also be extended if redundant termination of the second conductors 23a is desired.

A standard typewriter keyboard 130 (FIG. 5) can also be accommodated by the matrix switch 1% embodied as illustrated in FIG. 5B. In this embodiment consecutive rows 45b of the apertures 41b are designated by reference numerals 51, 53, 55, and 57. Also, it will be noted that particular ones of the second conductors 23b, such as the particular conductors 59 and 61, can extend through a switch 20b in each of an alternate pair of rows 51, 53, 55, and 57. For example, the particular conductor 59 extends through a switch 20b in each of the rows 53 and 57 and the particular conductor 61 extends through a switch 20b in each of the rows 51 and 55. Each of the particular second conductors 23b extending through a pair of switches 20b is preferably bisected between the associated pair of the switches 20b. Thus, the bisected second conductors 23b provide a plurality of third conductors 63 terminating on the second side 50b of the second backing member 29b and a plurality of fourth conductors 67b terminating on the first side 48b of the second backing member 29b. The bisecting of the second conductors 23b can be accomplished by punching a plurality of holes, such as the holes 71, through the laminate so as to sever the particular second conductors 23b between the associated pair of the switches 20b. In the preferred embodiment, each of the holes 71 is defined in part by discrete portions of one of the particular second conductors 23b at a location between the adjacent rows 53 and 55 of the switches 20b.

Also in this embodiment, it is particularly desirable that both the first and second edges 48b and 50b of the second backing member 29b extend beyond the first backing member 27b and the dielectric spacer 39!) so that the third conductors 63 are exposed on the second edge 50b and the fourth conductors 67 are exposed on the first edge 48b. This embodiment of the matrix switch 19b is particularly advantageous since a discrete switch is provided for each of the keys on the keyboard but the number of second conductors 23b is substantially one half the number illustrated in the matrix switch 19a shown in FIG. 5A.

The concepts of this invention can be embodied to accommodate keyboards wherein the keys are disposed in rows and columns which are substantially perpendicular to the rows. Furthermore, the spacing of the columns may not be symmetrical. These characteristics are typified by a common adding machine keyboard of the type shown generally at 130 in FIG. 6. The keys 150 of the keyboard 130 are arranged in a first group 64 of numerical keys disposed between a second and third group 66 and 68, respectively, of function keys. The rows 450 of the keys I50 include consecutively adjacent rows 69, 71, 73, and 75 which are common to each of the groups 63, 65, and 67. Similarly, the columns 470 of the keys 150 include the columns 77 and 79 in the first group 64 and the column 81 in the third group 68. The columns 47c can have a first angular re lationship, such as a perpendicular relationship, with the rows 45c.

On the keyboard the spacing between adjacent columns within each of the groups, such as the columns 77 and 79 in group 64, can be less than the spacing between adjacent columns in adjacent groups, such as the columns 79 and 81 in the first and third groups 64 and 68, respectively. For example, in a preferred embodiment the columns 77 and 79 are spaced 0.750 inches while the columns 79 and 81 are spaced [.125 inches.

A matrix switch 19c embodied as illustrated in FIG. 6A can include switches 20c spaced in accordance with the spacing of the keys 15c of the keyboard 130 (FIG. 6). In this embodiment the first conductors Zlc extend in a first direction corresponding to the rows 69, 71, 73, and 75 of the keys 15c. The second conductors 236 preferably extend in a second direction having an an gular relationship with both the columns 47c of the key and the first conductors 210. For example, the second conductors 230 can be disposed at an angle 26 34' to the direction of columns 470. At this angle some of the second conductors 23a such as the conductors 83 and 85 will extend between a switch 20c in each of an alternate pair of the rows 45c. For example, the conductor 83 extends through a switch 201 in each of the rows 69 and 73 and the conductor 85 extends through a switch in each of the rows 71 and 75. The second con ductors 23c extending through a pair of the switches are preferably bisected between the pair of switches to provide a terminal for each of the switches on one of the edges 48c and 500 of the backing member 29.

Due to the increased spacing between the columns 470 in adjacent groups, some of the second conductors 230, such as the particular conductor 87, may extend through only one of the switches 200, such as the associated switch 88. The particular second conductor 87 need not be bisected in which case the associated switch 88 is terminated on both of the edges 48c and 50c of the second backing member 29c.

The increased spacing between the columns 47c in adjacent groups can also provide second conductors 23c which extend through a pair of switches 20c disposed in non-alternate rows. Thus, the particular sec ond conductor 82 extends through the switches 84 and 86 in the rows 69 and 75. The particular second conductor 82 is preferably bisected so that the switches 84 and 86 are individually terminated on one of the edges 48c and 50c.

The concept of the switching matrix can be embodied to accommodate a keyboard having a plurality of keys aligned in rows and columns which are evenly spaced. Such a matrix might include the switches 20d which are illustrated in FIG. 7 to be symmetrically spaced to correspond to the spacing of the keys. in FIG. 7, 20 of the switches 20d are consecutively lettered from A to T and disposed in four rows and five columns. The switching matrix 19a is merely representative of that which can be used with any symmetrical keyboard having any number of keys. Furthermore, although the switches A to T have a symmetrical spacing of 0.75 inches in the preferred embodiment, the concept of the invention can be applied to any spacing of the keys and switches.

As illustrated in FIG. 7, the switches A to T are arranged in rows 83 and columns 85 and the columns 85 have an angular relationship such as a perpendicular relationship to the rows 83. The first conductors 21d can extend individually through the rows 83, and the second conductors 23d can be disposed in an angular relationship with both the rows 83 and columns 85. The second conductors 230 can include a series of conductors, such as the series of conductors 87 and 89, for each of the columns 85 of the switches A to T. The number of conductors in each of the series of conductors 87 and 89 can be equal to the number of rows 83 of the switches 20d. This will enable conductors in each of the series of conductors 87 and 89 to extend through one of the switches 20a in the associated column 85 of switches 20d. This configuration can provide a terminal for each of the switches A to T in accordance with the corresponding letters on the first edge 48d.

In the preferred embodiment, the switches 20d are disposed on 0.75 inch centers and the second conductors 23d have a maximum width of 0.125 inches. With these dimensions, the matrix switch 19d could be expanded to include six switches 20d in each of six rows 45d.

If the columns 85 are more closely spaced. it may be advantageous that some of the second conductors 23 extend through more than one of the switches 20.

Under such circumstances, the matrix switch 192 shown in FlG. 7A may be particularly desirable. In this embodiment. some of the second conductors 232 may be shared between adjacent series of conductors, such as the series 87c and 89e. For example, the particular conductors 91 and 93 are included in both the series of conductors 87e and 89e. These particular conductors 91 and 93 extend through a switch in each of an adjacent pair of the columns e so that it is desirable to bisect the particular conductors 91 and 93 between the associated switches. Thus, the particular conductor 91 is bisected between the switches B and K and the particular conductor 93 is bisected between the switches G and P. This will provide each of the associated switches with a discrete terminal. Thus, in the switching matrix 19e, the second conductors 23e of each of the switches A to T are terminated in accordance with the respective letters on the edges 482 and 50a of the second backing member 29e. It will also be noted that the common line 49a is shown to be welded to each of the first conductors 21e through a plurality of apertures 38 in the spacing member 39c.

Since a single second conductor 23e can accommodate more than one switch, the ultimate size of the matrix is significantly increased. For example, if the switches 20a are on 0.75 inch centers and the second conductors 23? have a maximum width ofO. l 25 inches, the matrix switch 19e can be expanded to accommodate 12 switches 20a in each of 12 rows. Even larger matrices can be made if the spacing of the switches 20e is increased or the width of the second conductors 23e is decreased.

A keyboard having symmetrically spaced keys can be provided with a switching matrix of still another embodiment wherein the angular relationship of the rows 45 and columns 47 is the same as the angular relationship of the first conductors 21 and the second conductors 23. Thus, the matrix switch can be embodied, as in FIG. 73. to accommodate switches symmetrically spaced in rows 45f, including an adjacent pair of particular rows 95 and 97. Particular ones of the first conductors 21f can individually extend through the switches 20f in each of the rows 45f. For example. a particular conductor 99 can extend through the switches 20f in the row 95 and a particular conductor 101 can extend through the switches 20fin the row 97. Additionally, an intermediate first conductor 21f can extend between each of first conductors 21f which pass through the switches 20fin an adjacent pair of the rows 45f. For example, the intermediate conductor 103 can extend between the particular conductors 99 and 101.

Similarly, the second conductors 23f can include a particular conductor 105 and a particular conductor 107 each extending through an adjacent pair of the columns 47f. The second conductors 23f can also include an intermediate second conductor 109 extending between the particular conductors 105 and 107.

In addition to the apertures 41f, the dielectric spac ing member 39 can include a plurality of apertures 111 which are disposed at the points of intersection between the particular first conductor 103 and each of the second conductors 23f. The conductor 103 and each of the second conductors 23f can be electrically connected by welding or soldering through each of the apertures 11]. Each of the particular second conduc tors passing through the switches 20f, such as the con ductors 105 and 107, are preferably bisected between the particular first conductors 99 and 103. This can be accomplished by punching a hole, such as the hole 113, through the laminate in a manner similar to the punching of the holes 71 f so that the conductors I and 107 are severed. The intermediate first conductors 103 is also preferably bisected between the particular second conductors 105 and 107 and on one side of the intermediate second conductor 109. This bisecting can be accomplished by punching a hole, such as the hole 115, through the laminate so that the intermediate first conductor 103 is severed at the location of the hole 115.

In this manner, the switches disposed on the particular rows 95 and 97 can be provided with discrete terminals on one of the edges 48 and 50f as illustrated by the respective letters A to T. An additional pair of the rows 45f of switches 20f can be accommodated by the second conductors 23f so that the switches 20f associated therewith are terminated on the opposite edge 50f of the second backing member 29. As previously noted, it is desirable in such an embodiment to bisect the second conductors typically by punching the holes 71f through the laminate between the associated pairs of the rows 45f.

The matrix switch 19 of the present invention can be embodied as illustrated in FIG. 12 to terminate on a standard collated cable adapter board 165 which has a plurality of conductors 167 printed thereon. In this particular embodiment, the first conductors 21g are arranged in pairs, and each of the pairs is associated with one of the switches 203. For example, a particular pair of the conductors 21g include a conductor 171 and a conductor 173, both of which are associated with the key having the indicia 7. As in some of the previous embodiments, each of the second conductors 23g is associated with a particular row of the switches 20g.

The dielectric spacing member 39g separates the first and second conductors 21g and 23g, respectively, except in the general areas of their intersection. In each of these areas, one of the keys (FIG. 4) is disposed to press the associated pair of the first conductors 21g into electrical contact with the associated second conductor 23g. Thus, by pressing an individual key 15, the signal present on one of the conductors in the associated pair of first conductors 21g passes through the associated second conductor 23g to the other of the conductors in the particular pair of first conductors 21g. For example, by pressing the key associated with the indicia 7, the signal present on the conductor 171 is shorted across the associated second conductor 23g to the conductor 173. It is apparent that in this particular embodiment the second conductors 233 function primarily to short the conductors 213 in a particular pair of the conductors 21g. Also, it will be noted that generally speaking, the first conductors 21g are not directly and permanently connected to the electronics associated with the particular operation.

A collated cable 175 can be disposed with its substantially parallel conductors 177 extending transverse to the first conductors 21 g and respectively terminating on the conductors 167. Generally, the switches g can be connected to the conductors 177 in accordance with random groupings of the switches 20g. For example, the switches 20g can be formed into a plurality of first groups including all of the switches 20g and a plurality of second groups including all of the switches 20g. Each of the switches 203 is included in one of the first groups and one of the second groups, so that the number of switches 20g can be no greater than the product obtained by multiplying the number of first groups by the number of second groups. The conductors 177 can be designated to correspond respectively to one of the first or second groups of switches 20g. Then, each of the pairs of first conductors 21g can be electrically connected to those conductors 177 which have the particular first and second group designations correspond ing to the associated switch.

Referring to FIG. 12, it will be noted that the conductors 177 include particular conductors 179 and 181 which correspond to two random groups of switches 20g among the function switches shown generally at 183. Also, the particular conductors 187, 189, and 191 correspond to the three random groups of switches 20g among the numbered switches shown generally at 185. The particular conductor 191 also corresponds to the group of switches to the right of the numbered switches 185. The pairs of conductors 21g for each of the switches 203 can be connected as previously described. This is merely one example of how the switches 20g can be formed into first groups to facilitate repairs, wherein a particular failure can be localized to the function switches or the number switches.

Of course, the first and second groups of switches 20g can correspond respectively to the rows and columns of the switches 20g. Then, each of the pairs of first conductors 213 can be electrically connected to those conductors 177 which have the particular row and column designations corresponding to the associated switch.

This particular matrix switch can be formed as a laminate as shown in FIG. 14. The first backing member 27g and the dielectric spacing member 393 can extend substantially across the entire matrix switch 19g with the first conductor 21g sandwiched therebetween.

A separate collated cable including the backing member 293 and the shorting second conductors 233 can be disposed on the side of the spacing member 39g opposite the first conductors 21g to form the switches 20g. A further collated cable including the conductors 177 can be simultaneously located on the side of the spacing member 39g opposite the first conductors 21g, typically in spaced relationship to the switches 20g.

In addition to the apertures 41g which can be formed between the first and second conductors 21g and 23g, respectively, the spacing member 39g can also be provided with an aperture 193 at each of the points of intersection where one of the first conductors 213 is to be connected to one of the conductors 177. In such an embodiment, the associated conductors 21g and 177 are connected through the associated apertures I93. Alternatively, at each of these points of intersection, the associated conductors 23g and 177 can be soldered, resistance-welded, ultransonically welded, or otherwise connected by melting the backing member 293 and the dielectric spacer 39g at each of the points of connection. Such a weld is shown generally at 195 in FIG. 13. Although the conductors 23g and the conductors 177 are illustrated to be included in separate collated cables, it will be apparent that these conductors can be collated on a single backing member.

As illustrated in FIG. 14, a matrix switch 19 similar to that shown in FIG. 12 can be provided to accommodate a standard typewriter keyboard. In such an embodiment. the first and second conductors 21h and 23h may be oriented in substantially perpendicular directions. It is of interest to note that the pairs of first conductors 21h include a first and second particular pair of conductors which are designated generally by the reference numerals 197 and 199, respectively. The second conductors 2311 also include a particular pair of conductors which is designated by the reference numeral 201. These conductors are of particular interest since the particular first conductors 197 pass through the switches associated with both the letter B and the space." Thus, the particular conductors 197 violate the general rule that a single pair of the second conductors 23h should be associated with only a single switch 2011.

In such a case, the particular conductors 197 can be cut or otherwise provided with a discontinuity between the associated pair of switches designated B and space." Then the particular conductors 197 can be soldered or otherwise connected to the particular conductors 201 as illustrated generally at 203. Similarly, the particular conductors 201 can be connected to the conductors 199 as illustrated generally at 205. The conductors 199 can be connected to the conductors 17712 of the collated cable l75h in the manner previously discussed.

Referring again to FIG. 1, it will be noted that the matrix switch 19 can register with the bar clamp 25 to provide an interface between the switch and the associated electronics (not shown) of the controlled operation. Referring now to FIG. 9, it will be noted that the bar clamp can include first retaining means 125 which cooperates with a clamp plate 127 to receive the ends of the second conductors 23. In such an embodiment, the second conductors 23 can face the first retaining member 125 so that the outer surface 37 of the backing member 29 contacts the clamp plate 127. The first retaining member 125 preferably includes portions 130 which define a plurality of first slots 131 each aligned with and receiving one of the second conductors 23. The matrix switch 19 may be maintained in a substantially fixed relationship with the bar clamp 25 by the frictional engagement of the portions 130 and the conductors 23, and the frictional engagement of the clamp plate 127 with the backing member 29.

A plurality of conductors 133 preferably extend from an outer surface of the first retaining member 125 to contact respectively the second conductors 23. The conductors 133 are preferably formed from discrete strips of material each having a relatively high electrical conductivity.

Each of the conductors 133 can be constructed to exert a force upon the associated second conductors 23 to enhance the electrical contact therebetween. For example, the conductors 133 can include first portions 135 having a substantially fixed relationship with the first retaining member 125, and the portions 137 slidingly engaging the first retaining member 125 interiorly of the slots 131. Third portions 139 of the conductors 133 can extend between the first and second portions 135 and 137, respectively, to contact the associated second conductors 23. If the third portions 139 are normally biased to extend from the slots 131 then they will exert a pressure upon the second conductors 23 when the portions 130 contact the second conductors 23.

It will be apparent to those skilled in the art that the first retaining member 125 can be molded from an insulating material with the portions 135 of the conductors 133 embedded in the first retaining member 125. It may be desirable, however, that the conductors 133 more loosely engage the first retaining member to facilitate replacement of the conductors 133. In such an embodiment. the first retaining member 125 can be constructed to define a plurality of slots 141. The slots 14] preferably extend from each of the slots 131, along the surface of the member 125 facing toward the switches 20, and terminate at the surface of the member 125 facing away from the switches 20.

A second retaining member 143 can be disposed to engage the first retaining member 125 to form a channel 145 with each of the slots 141. The conductors 133, which preferably extend through the channels 145 are loosely held in a substantially fixed relationship between the first and second retaining members 125 and 143, respectively. Portions 146 of the conductors 133 extending from the channels 145 can be configured to facilitate their connection to conductors 148 of the as sociated electronics. In this manner, the bar clamp 25 interfaces the matrix switch 19 with the associated electronics by providing electrical continuity between the conductors 23 and the conductors 148.

It will be apparent to those skilled in the art that the bar clamp 25 is particularly adapted for use with a clamp plate 127, such as a board having a circuit 129 printed on the surface thereof. As illustrated in FIGS. 10 and 11, the first retaining member 125 preferably contacts the outer surface 37 of the backing member 29 so that the second conductors 23 are forced into electrical contact with the circuit 129. In such an embodiment, the conductors 133 may not carry any signal, in which case their primary function is to exert pressure upon the backing member 29 to facilitate the electrical contact between conductors 23 and the circuit 129. It will be appreciated by those skilled in the art that this function can be performed by any biasing means preferably extending between the first retaining member 125 and the backing member 29.

The first and second retaining members 125 and 143. respectively, and the conductors 133 can be constructed in a subassembly. In such a subassembly, the first and second retaining members 125 and 143, respectively, may define at least a pair of apertures 147 extending substantially perpendicularly to the clamp plate 127. A tubular member 149 for each of the apertures 147 can be provided with a flanged end 153 and a flangable end 151. After the conductors 133 have been disposed in the slots 141, the second retaining member 143 can be brought into cotiguous relationship with the first retaining member 125 so that the apertures 147 in the first and second retaining members 125 and 143, respectively, are aligned. In this position. the second member 143 caps the slots 141 to partially define the channels 145. With each of the apertures 147 aligned, the flangable end 151 of each of the tubular members 149 can be passed through the respective apertures 147 until the flanged end 153 contacts the second retaining member 143. Then the flangable end 151 can be flanged to contact the first retaining member 125 and thereby complete the subassembly.

The clamp plate 127 can be constructed to define a hole 155 having a coaxial relationship with each of the apertures 147. A threaded member, such as the bolt 157, can be passed through each of the tubular members 149 and the associated holes 155 until the head of the bolt 157 engages the flanged end 153. A nut 159 can be screwed on the threads of the bolt 157 to engage the clamp plate 127. In this manner, the subassembly including the conductors 133 can be held in fixed relationship with the clamp plate 127, with the backing member 29 and the conductors 23 sandwiched therebetween. It may also be desirable that the backing member 29 be provided with a hole l6l preferably aligned with each of the apertures 147 to receive the bolts 157. This embodiment will enable the matrix switch 19 to be bolted to the bar clamp and the clamp plate 127.

The switching matrix 19 of the present invention provides a significant advance over the prior art. Major steps in the formation of each of the embodiments illustrated and described can be accomplished in accordance with the high-speed methods associated with collated cable, so that the switching matrix l9 can be constructed at a significantly low cost per switch.

Although the switching matrix 19 can be formed with the planar spacing member 39, particular embodiments may be more advantageously constructed with the longitudinal spacing members 39'. The longitudinal spacing members 39' can be collated on the backing member 27 simultaneously with the disposition of the first conductors 21 thereon. This not only eliminates a separate part, but also significantly reduces problems associated with alignment and quality control. The matrix switch 19 can be adapted to operate in conjunction with many of the standard keyboards associated with typewriters, adding machines, and computers, etc.

The matrix switch 19 can be terminated by the bar clamp 25 not only to hold the switching matrix 19 in a fixed position with respect to the keyboard 13, but also to provide the automatically biased conductors 133 which receive the signals from the second conductors 23 and provide an interface with the associated electronics. Alternatively, the bar clamp 25 can be used in conjunction with a board 127 having a circuit 129 printed thereon in which case the biased conductors 133 force the second conductors 23 into electrical contact with the circuit 129 on the board 127.

Although this application has been disclosed and illustrated with reference to particular applications, the principles involved are susceptible of numerous other applications which will be apparent to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

I claim:

1. A switch assembly having a plurality of switches for switching an input signal and being adapted for use with a keyboard having a plurality of keys each associated with one of the switches, the keys being aligned in a plurality of rows each extending in a first direction and a plurality of columns each extending in a second direction transverse to the first direction, the assembly comprising:

a first backing member having a substantially planar inner surface and electrical insulating properties;

a plurality of first conductors disposed on the inner surface of the first backing member and each having the input signal thereon, the first conductors extending in the first direction and spaced in electrically insulated relationship to one another;

a second backing member having a substantially planar inner surface and electrical insulating properties;

a plurality of second conductors disposed on the inner surface of the second backing member and extending in a third direction different from the first direction and the second direction and spaced in electrically insulated relationship to one another, at least one particular conductor included among the second conductors on the second backing member and extending in close proximity to an associated pair of the first conductors on the first backing member at a particular pair of the switches;

portions of at least the second backing member defining an aperture which extends across and interrupts each of the particular conductors to break the electrical continuity of the associated particular conductor between the associated particular pair of the switches;

insulation means disposed in juxtaposition to the inner surface of the first backing member and the inner surface of the second backing member for normally insulating the first conductors from the second conductors, the insulating means defining a plurality of openings between the associated first conductor and the associated second conductor at each of the switches; whereby the keys of the keyboard are actuable to move the associated second conductor through the associated opening in the insulation means and into electrical contact with the associated first conductor to switch the input signal from the associated first conductor to the associated second conductor.

2. The switch assembly recited in claim 1 further comprising:

means for introducing the input signal to one of the first conductors; and

one of the second conductors being electrically connected to each of the first conductors so that the input signal introduced to the one first conductor is introduced to all of the first conductors.

3. The switch assembly recited in claim 1 wherein the second direction is substantially perpendicular to the first direction.

4. The switch assembly recited in claim 3 wherein the third direction is substantially perpendicular to the first direction.

5. A combination for providing a plurality of switches disposed in at least first, second, third and fourth consecutively adjacent rows and a plurality of columns, the switches having properties for being selectively actuated to control an operation, the combination including:

a plurality of first conductors disposed to extend in a first direction in electrically insulated relationship to one another and including among the plurality of first conductors a particular first conductor;

a plurality of second conductors disposed to extend in a second direction different than the first direction in electrically insulated relationship to one another and including among the plurality of scond conductors a particular second conductor;

a spacing member having properties for electrically insulating the first conductors from the second conductors and including particular portions thereof defining an opening between the particular first conductor and the particular second conductors;

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