US3081416A - Step-by-step switch - Google Patents

Description

T. W. TUTTLE ETAL March 12, 1963 STEP-BY-STEP SWITCH Original Filed March 19, 1956 3 Sheets-Sheet 1 -INVEINTORS THOMAS M TUTTLE March 12, 1963 "r. w. TUTTLE ETAL 3,081,416

STEP-BY-STEP SWITCH Original Filed March 19, 1956 3 Sheets-Sheet 2 may March 12, 1963 T. w. TUTTLE ETAL 3,081,416

STEP-BY-STEP swnca Original Filed March 19, 1956 s Sheets-Sheet a wiry/777% l N V ENTO R S United States Patent 3,081,416 STEP-BY-STEP SWITCH Thomas W. Tuttle, Nutley, and George F. McCarthy, Teaneck, N.J., assignors to International Telephone and Telegraph Corporation, Nutiey, N.J., a corporation of Maryland Continuation of application Ser. No. 572,468, Mar. 19, 1956. This application Apr. 19, 1961, Ser. No. 104,123 8 Claims. (Cl. 317-112) This invention relates to step-by-step switches used in automatic telephony and more particularly to a switch contact bank construction employing printed circuitry and is a continuation of application Serial Number 572,468 filed March 19, 1956, and now abandoned.

One of the objects of this invention is to provide a printed multiple for each level of the switch wherein a shield is provided between the multiples of adjacent levels.

Another object of this invention is to provide means to make the distance between adjacent pairs of conductors as large as practical with respect to the distance between the two conductors forming the pair in order to minimize, without resort to transposition schemes, the electrostatic and electromagnetic interaction between pairs of conductors in a line bank level and between pairs of. conductors in adjacent levels.

Another object is to provide a stacking arrangement for the printed multiples wherein the printed card of each level may be removed or replaced without requiring the disassembly of any other level in the stack.

One of the features of the invention is the manner of preparing the cards for a series of selector banks whereby a printed multiple is provided for the corresponding contacts of adjacent banks and the multiples of adjacent levels are shielded one from the other. Each level includes a card of dielectric material having conductors in the form of narrow strips on one side to constitute the horizontal multiple and a layer of conductive material extending over substantially the entire area of the other side to constitute an electrostatic shield between the horizontal multiple of its level and the horizontal multiple oi the next adjacent level. The contacts for each bank are provided in an are along one edge of the card preferably on both sides of the card with interconnections extending through the card. The contacts on the side containing. a layer of conductive material together with the leadstherefor are formed by narrow channels in the conductive layer. The leads thus formed extend crosswise of the card and are connected through the card to the corresponding conductors of the horizontal multiples on the opposite side. These cards together .with spacing cards of dielectric material are assembled and aligned wtih clamping means. To remove or replace any one card the aligning means are first removed and the clam-ping means loosened thereby permitting such removal or replacement.

Another of the features of the invention is the manner of preparing the cardsfor a series of line selector banks whereby a printed multiplee of all conductors forming one side ofi the pairs of conductors within the level assembly are the mirror image of all the conductors forming the other side of the pairs of conductors within the level assembly, thus bringing the two conductors of each pair in 'very close proximity throughout the entire length of the of, the card containing the conductive shield and leads to the contacts;

multiple conductors 2-12.

3,081,416 Patented Mar. 12, 1963 FIG. 2 shows in plan the opposite side of the card illustrated in FIG. 1;

FIGS. 3 and 4 show in plan two cards which are combined to provide one unit of the line bank;

FIG. 5 shows a bank stack assembly in longitudinal cross-section of printed cards and dielectric spacers, the section being taken along line S -S of FIG. 1; and

FIG. 6 is a view in vertical cross-section of a bank stack taken along line 6 6- of FIG. 1.

In the prior art telephone bank switches are interconnected by individual wire leads which have substantial loops to permit changes in connections, if errors have been made in the connections, as often happens. The result is that such wired apparatus present a clumsy and untidy appearance in addition to being susceptible to errors. It has been proposed to use in telephone switchboard assemblies electrical connecting strip made from metallic foil and folded over to provide a succession of multiple connections which may be used in telephone switchboard assemblies. However this proposed method, while it eliminates wires, does not have continuous strip conductors but provides connections from one switch group to another in a repetitive fashion.

Referring to FIGS. 1, 2 and 6 of the drawings, each level of the private bank portion of the step-bystep switch is shown to comprise a dielectric card 1 which has on one side thereof a plurality of conductors 2 to 12 in the form of narrow strips extending lengthwise of the card which comprise the horizontal multiple connecting corresponding contacts of a plurality of banks, such as indicated by the two adjacent arcuate sections 13 and '14 in FIGS. 1

and 2. Each bank section includes eleven contacts which are printed on the same side oi the card as the horizontal The contacts 15 of the end section 13- are connected directly to the ends of the conductors 2-12 but the contacts 16 of the other sections, such as at 14, are connected to corresponding conductors of the horizontal multiple by leads formed in the conductive "shield 17 through contacts 16a on the other side of the card. These leads are indicated at 18.

While the printing of the conductive material on the dielectric card'may follow any one of many different circuit printing techniques, the one described herein for purposes of illustration is commonly refer-red to as the etching method. The dielectric card 1 may be of any suitable dielectric, either polyethylene, polystyrene, Teflon, fiber glass or laminations of fiber glass and Teflon. The cards are originally clad with copper foil on each side'and the portions to be retained are coated with acid resisting material after which the card is subjected to an acid etching solution which removes the unwanted portions of the copper foil. The side 015 the card shown in FIG. 1 comprises the shield in which the contact areas ductors of the horizontal multiple on the opposite side.

Each opening 22 is shown to be connected through the card to a corresponding horizontal conductor. The interconnection is usually formed by dipping the entire card in a bathof solder thereby forming all interconnections simultaneously. The card 1 is also provided with narrow slots '23 between adjacent contact areas so as to avoid wiping particles of dielectric onto the contacts. The corresponding contact areas 15, 15a and 16, 16a on cpposite sides of the card are interconnected by openings 24 which are soldered during the solder-dipping operation.

The leads 18 are similarly connected to corresponding conductors of the horizontal multiple as indicated by the interconnection 24.

From the foregoing description it will be clear that the card for the private bank comprises a dielectric member on which the conductors of the horizontal multiple are printed on one side together with corresponding contacts for each section. The other side of the card is covered with a layer of conductive material 17 in which contact areas and leads are formed by narrow Channels formed in the conductive material 17. This leaves that side of the card substantially covered with conductive material which when the card is assembled with other cards in a stack, the layer 17 constitutes an electrostatic shield bteween the horizontal multiples of adjacent levels. This formation is clearly illustrated in FIG. 6 wherein cards 26 and 27 comprise adjacent levels separated by a layer of dielectric 28. The layer of conductive material 17 of the card 27 comprises the shield between the horizontal multiple of the card 27 and the horizontal multiple of the next adjacent card 26.

FIGS. 3 and 4 show the construction of the cards of the line bank. They are formed similarly as described for the cards of the private bank. In the illustrations of FIGS. 3 and 4, the printing on the opposite sides in each view is shown in dotted lines. Each level of the line bank, however, comprises two such cards, FIG. 3 showing card 29 and FIG. 4 showing card 30', the two being separated by a thin layer of dielectric as shown in cross section of FIG. 6. FIG. 3 shows the card 29 as viewed from the top in FIG. 6, while the card 30 shown in FIG. 4 is viewed from the bottom of FIG. 6.

Referring particularly to FIG. 3 the card 29 is shown to have contact areas 32 which are separated by dummy contacts 33. The space between each dummy contact and the adjacent active contact may include a slot 34 which extends through the card. Each of the active contacts 32 are connected by leads 35 formed on the opposite side of the card for connection with corresponding conductors 36 of the horizontal multiple. The end section of the card is also provided with terminals 37 which are likewise provided with leads 38 formed in the electrostatic shield for connection through the card to corresponding conductors of the horizontal multiple.

Referring to FIG. 4 the card is formed in a similar manner except that the printing is directly opposite to that shown in FIG. 3 whereby the two cards may be assembled with the horizontal multiples directly opposed as shown in FIG. 6. The active contacts for card 30 are indicated at 39 and the horizontal multiples are indicated at 40. The conductive shields for the cards 29 and 30 are indicated at 41 and 42. In manufacture these cards 29 and 30 are assembled with a thin intervening layer of dielectric 31 and sealed together to form a single unit. In assembling cards 29 and 30 it is important to space them together as close as possible. This is accomplished by making the thickness of the sheet of dielectric 31 in the neighborhood of .005 inch. This brings the conductor strips into mirror image relationship throughout the lengths of the cards, and the conductive layers 41 and 42. form in effect a shield between the conductor pairs of the level, each conductor pair being the two corresponding strips, such as 54 and 55 (FIGS. 3, 4 and 6) of cards 29 and 30 on opposite sides of the dielectric 31.

These units are assembled together with dielectric spacing layers 43 to form the assembled bank. The cards of the bankas indicated in FIG. are aligned by threaded rods 44 and 45 which pass through alignment openings 46, FIG. 1, and 47, FIG. 3. The cards are clamped between two frame members 48 and 49 by end bolts 50. The elements 44 and 45 are threadably received in the frame member 49. When it is desirable to remove or replace one of the cards or assembled units 29-30, the alignment rods 44 and 45 are removed and the clamping bolts 50 loosened. This permits the removal of any desired card without disassembling the other cards.

In FIG. 6 the wipers are inlicated in dotted lines. For the private bank a double contact wiper is shown at 51 which engages the corresponding contact areas of the card as the wiper is moved along the arc containing the contacts. The wipers '52 and 53 comprise the wipers for the line bank, the wiper 52 engaging the active contacts of card 29 while the wiper 53 engages active contacts of card 30.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the accompanying claims.

We claim:

1. A switch contact bank assembly comprising a plurality of levels each provided with a plurality of conductors coupled as the horizontal multiple to successive groups of contacts, each of said levels comprising a card of dielectric material having continuous conductive strips extending lengthwise of said card constituting the horizontal multiple and a plurality of first groups of contacts on one side, and a separate layer of conductive material in a given plane on the other, extending over substantially the entire area thereof to constitute, in effect, an electrostatic shield relative to said conductive strips, said layer of conductive material having narrow channels therein to define conductive leads between adjacent channels separated by portions of said conductive material, said separating conductive material constituting, in effect, an electrostatic shield between said leads, means conductively connecting said conductive leads through said card to corresponding ones of said conductive strips, a plurality of a second group of contacts on said other side opposite said plurality of first groups of contacts, each one of a second group of contacts being connected to a corresponding one of said oppositely disposed first group of contacts through said card, and means connecting each coupled pair of oppositely disposed contacts to a connected conductive lead and conductive strip, said first and second group of contacts being adapted for engagement by a contact wiper.

2. A switch contact bank assembly according to claim 1 wherein said conductive leads extend substantially crosswise of said card, and said first and second groups of contacts are disposed in arcuate portions along one edge of said card.

3. A switch contact bank assembly comprising a plurality of levels each provided with a plurality of conductors coupled as the horizontalmultiple to successive groups of contacts, each of said card-s comprising a card of dielectric material having continuous conductive strips on one side extending lengthwise of said card constituting said horizontal multiple and a plurality of first groups of contacts on said side, and a separate layer of conductive material in a given plane on the other side extending over substantially the entire area thereof to constitute, in efiect, an electrostatic shield between the horizontal multiple of its level and the horizontal multiple of the next adjacent level, said layer of conductive material having narrow channels therein to define conductive leads between adjacent channels separated by portions of said conductive material, said separating conductive material constituting, in effect,

an electrostatic shield between said leads, means conductively connecting said conductive leads through said card to corresponding ones of said conductive strips, a plurality of second groups of contacts on said other side opposite said plurality of first groups of contacts, each one of a second group of contacts being connected to a corresponding one of said oppositely disposed first group of contacts through said card and means connecting each coupled pair of oppositely disposed contacts to a connected conductive lead and conductive strip, said contacts of said first and second groups being adapted for engagement by a contact wiper.

4. A switch contact bank assembly comprising a plurality of levels each provided with a plurality of conductors coupled as the horizontal multiple to successive groups of contacts, at least certain of said levels compris ing two cards of dielectric material each said card having conductive strips on one side constituting said horizontal multiple and a first group of contacts on said side, and a separate layer of conductive material ina given plane on the other, extending over substantially the entire area thereof to constitute, in effect, an electrostatic shield relative to said conductive strips, a layer of dielectric material disposed between said cards with the sides carrying said horizontal multiple strips facing each other to form conductor pairs, the layer of conductive material of each of said cards having narrow channel-s therein to define conductive leads between adjacent channels separated by portions of said conductive material, said separating conductive material constituting in effect an electrostatic shield between said leads, the conductive layers of said card-s constituting, in effect, also an electrostatic shield between the horizontal multiple of its level and the horizontal multiple of the next adjacent level and between conductive pairs in the level, mean-s in each card conductively connecting said conductive leads through said card to corresponding ones of said conducting strip, a second group of contacts on said other side opposite said first group of contacts, each of said second group of contacts being connected to a corresponding one of said first group of contacts through said card, and means connecting each coupled pair of oppositely disposed contacts to a connected conductive lead and conductive strip, said contacts of said first and second group being adapted for engagement by a contact wiper.

5. A switch contact bank assembly according to claim 4 further comprising a plurality of spacer cards of dielectric, means for aligning the cards of said level with spacer cards therebetween and means zfior clamping all of said cards together.

6. A switch contact bank assembly comprising a plurality of levels each provided with a plurality of conduc tors coupled as the horizontal multiple to successive groups of cont-acts, each of said levels comprising a pair of cards of dielectric material, each said cards having conductive strips constituting said horizontal multiple and a first group of contacts on one side, a separate layer of conductive material in a given plane on the other side, extending over substantially the entire area thereof to constitute, in effect, an electrostatic shield relative to said conductive strips, said layer of conductive material having narrow channel-s therein to define conductive leads between adjacent channels separated by portions of said conconductive material, said separating conductive material constituting, in effect, an electrostatic shield between said leads, means conductively connecting said conductive leads through said card to corresponding ones of said conductive strips, a second group of contacts on said other side opposite said first group of contacts, each of said second group of contacts being connected to a corresponding one of said first group of contacts through said card, and means connecting each coupled pair of oppositely disposed contacts to a connected conductive lead and conductive strip, said contacts of said first and second groups being adapted for engagement by a contact wiper, means disposing said pair of cards in parallel dielectrlcally spaced relation with the conductive strips of each card facing each other as a mirror image of the corresponding conductive strips of the other card whereby the conductor pairs comprise one top conductor and one bottom conductor disposed parallel and in close proximity throughout their length, thus minimizing electrostatic and electromagnetic interaction between pairs of conductors in the levels.

7. A multiple conductor card comprising a card of dielectric material having continuous conductive strips extending lengthwise of said card and a plurality of first groups of contacts on one side, and a separate layer of conductive material in a given plane on the other side, extending over substantially the entire area thereof to constitute, in effect, an electrostatic shield relative to said conductive strips, said layer of conductive material having narrow channels therein defining conductive leads between adjacent channels separated by portions of said conductive material, said separating conductive material constituting, in effect, an electrostatic shield between said leads, means conductively connecting said conductive leads through said card to corresponding ones of said conductive strips, a plurality of second groups of contacts on said other side opposite said plurality of first groups of contacts, eachone of a second group of contacts being connected to a corresponding one of said oppositely disposed first group of contacts through said card, and means connecting each coupled pair of oppositely disposed contacts to a connected conductive lead and conductive strip, said contacts of said first and second groups being adapted for engagement by a contact wiper.

8. A multiple conductor card according to claim 7 wherein said conductive leads extend substantially crosswise of said card, and said first group and second group of contacts are disposed in arcuate portions along one edge of said card.

References Cited in the file of this patent UNITED STATES PATENTS 552,058 German Apr. 30, 1924 1,819,675 Chaplin Aug. 18, 1931 2,257,894 Winsor Oct. 7, 1941 2,259,103 Drake Oct. 14, 1941 2,298,236 Siegmund Oct. 6, 1942 2,441,960 Eisler May 25, 1948 2,586,854 Myers Feb. 26, 1952 2,616,994 Luhn Nov. 4, 1952, 2,634,310 Eisler Apr. 7, 1953 2,695,963 Thias Nov. 30, 1954

Claims (1)

1. A SWITCH CONTACT BANK ASSEMBLY COMPRISING A PLURALITY OF LEVELS EACH PROVIDED WITH A PLURALITY OF CONDUCTORS COUPLED AS THE HORIZONTAL MULTIPLE TO SUCCESSIVE GROUPS OF CONTACTS, EACH OF SAID LEVELS COMPRISING A CARD OF DIELECTRIC MATERIAL HAVING CONTINUOUS CONDUCTIVE STRIPS EXTENDING LENGTHWISE OF SAID CARD CONSTITUTING THE HORIZONTAL MULTIPLE AND A PLURALITY OF FIRST GROUPS OF CONTACTS ON ONE SIDE, AND A SEPARATE LAYER OF CONDUCTIVE MATERIAL IN A GIVEN PLANE ON THE OTHER, EXTENDING OVER SUBSTANTIALLY THE ENTIRE AREA THEREOF TO CONSTITUTE, IN EFFECT, AN ELECTROSTATIC SHIELD RELATIVE TO SAID CONDUCTIVE STRIPS, SAID LAYER OF CONDUCTIVE MATERIAL HAVING NARROW CHANNELS THEREIN TO DEFINE CONDUCTIVE LEADS BETWEEN ADJACENT CHANNELS SEPARATED BY PORTIONS OF SAID CONDUCTIVE MATERIAL, SAID SEPARATING CONDUCTIVE MATERIAL CONSTITUTING, IN EFFECT, AN ELECTROSTATIC SHIELD BETWEEN SAID LEADS, MEANS CONDUCTIVELY CONNECTING SAID CONDUCTIVE LEADS THROUGH SAID CARD TO CORRESPONDING ONES OF SAID CONDUCTIVE STRIPS, A PLURALITY OF A SECOND GROUP OF CONTACTS ON SAID OTHER SIDE OPPOSITE SAID PLURALITY OF FIRST GROUPS OF CONTACTS, EACH ONE OF A SECOND GROUP OF CONTACTS BEING CONNECTED TO A CORRESPONDING ONE OF SAID OPPOSITELY DISPOSED FIRST GROUP OF CONTACTS THROUGH SAID CARD, AND MEANS CONNECTING EACH COUPLED PAIR OF OPPOSITELY DISPOSED CONTACTS TO A CONNECTED CONDUCTIVE LEAD AND CONDUCTIVE STRIP, SAID FIRST AND SECOND GROUP OF CONTACTS BEING ADAPTED FOR ENGAGEMENT BY A CONTACT WIPER.

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