US3573404A

US3573404A - Programmable automatic selector switch

Info

Publication number: US3573404A
Application number: US817027A
Authority: US
Inventors: Daniel E Robinson
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-04-17
Filing date: 1969-04-17
Publication date: 1971-04-06
Anticipated expiration: 1988-04-06

Abstract

A selector switch for testing multiconductor cables, such as telephone cable. A contact board has a separate terminal connected with each conductor of the cable. A selector drum rotates under conductors on the contact board which are connected with the separate terminals of the contact board and the selector drum has contacts that pass across the conductors of the contact board to close circuits when not prevented from doing so by a belt that covers the drum. Perforations in the belt are located in positions to permit contact of different conductors and groups of conductors in accordance with a sequence which is programmed by the locations of the perforations in the belt.

Description

United States Patent [72] Inventor Daniel E. Robinson 38 Orchard St., Metuchen, NJ. 08840 [21 Appl. No. 817,027 [22] Filed Apr. 17, 1969 [45] Patented April 6, 1971 [541 PROGRAMMABLE AUTOMATIC SELECTOR SWITCH 15 Claims, 13 Drawing Figs.

[52] US. Cl 200/46, 324/51 [51 Int. Cl H0lh 43/08 [50] Field of Search 200/46; 324/73, 66, 51 (lnquired) [56] References Cited UNITED STATES PATENTS 3,176,091 3/1965 Hason et al. 200/46 47,@ AUTOMATIC POSITIONE POSITION INDICATOR 3,287,633 11/1966 Mollo ABSTRACT: A selector switch for testing multiconductor cables, such as telephone cable. A contact board has a separate terminal connected with each conductor of the cable. A selector drum rotates under conductors on the contact board which are connected with the separate terminals of the contact board and the selector drum has contacts that pass across the conductors of the contact board to close circuits when not prevented from doing so by a belt that covers the drum. Perforations in the belt are located in positions to permit contact of different conductors and groups of conductors in accordance-with a sequence which is programmed by the locations of the perforations in the belt.

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I PROGRAMMABLE AUTOMATIC SELECTOR SWITCH BACKGROUND AND SUMMARY OF THE INVENTION Multiconductor (coaxial pairs or twin pairs, etc.) cables require many electrical tests, both during production and on the finished cable. Making these tests requires long and tedious work and they are subject to many errors where multiconductors are used in various combinations.

This invention relates to a selector switch for cable conductors, and more specifically to a switch for multiconductor telephone cable which is to be tested with an automatic telephone cable tester.

Switches heretofore employed for the purpose have been connected through multileads, unit relay switches or stepping relay switches. In each case, these prior switches have had the disadvantage of electric signal coupling between units within the switch and they have thus added unwanted signals to the cables or devices under test. Further, the switches employed previously have been constructed in such a manner as to be difficult to service and clean. They have been expensive and have been characterized by relatively low dielectric strengths and relatively high contact resistance.

The switch of this invention is constructed so as to eliminate individual pair leads, thus eliminating lead signal coupling. The invention provides separation of contact boards for cleaning or replacement of contacts in the cae of damage or wear. This separation also has the important advantage that conductors of the cable to be tested can be connected with a contact board prior to the assembly of the contact board with an automatic cable tester. Thus the cable tester'can be employed on each cable in turn without waiting for the conductors of the cable to be connected, since the cable conductors have already been connected to the board ready to test, as the tester becomes available.

One of the main advantages of this switch is its programmable feature. A prerecorded pair selection program is punched on a belt tape contact separator in such a manner that each position of the belt selects two wires for input signal and two wires for output signal. These are usually the disturbing pair and disturbed pair in signal coupling (crosstalk), but any combination of one to four wires connected in any parallel or series manner to allow voltage breakdown can result in signal coupling.

The switch of this invention has no limit to the number of wires or conductors to be selected. For example: one wire can be tested against all others in a cable. Two switches of this invention can be used in tandem or remotely in such a manner as to synchronize their positions, thus further selecting either and combinations of input signal and output signal, and for terminal conditions such as short circuit, open circuit or impedance termination. One tape or belt can be programmed for tandem operation or two separate tapes can be used, if more convenient.

This invention has a selector board contact design which employs a simple strip of the usual contact material, such as phosphor bronze and the strip is fashioned to a shape to cooperate with contacts on a selector drum. The board contact strips are constructed so as to be easily removed and replaced and preferably consist of a narrow strip bent into shape and held in shape by mechanical rigidity or backed by resilient material such as rubber, supporting and yielding a springlike motion to give contact pressure and a wiping action =necessary to establish and maintain low resistance contact.

Contacts of a selector drum are located in a shielded housing assembly having individual shields or pair shields over their input and output conductors. The contacts of the selector drum are constructed to employ either a springloaded cap made to fit into the selector board contacts or a rigid construction. These contacts are fastened into the input and output conductors and protrude with the shielded assembly through guide holes in an insulated strip. The shield is necessary to prevent signal coupling between the input and output conductors. A selector drum contactor assembly is provided with spring loading and guides to press it against the inner face surface of the selector drum for contact pressure, and cams push it away from the drum face during the period when the apparatus is making a program advance to prevent wear and damage.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views:

FIG. I is a diagrammatic exploded view of a selector switch made in accordance with this invention;

FIG. 2 is a diagrammatic view showing the selector switch of FIG. 1 connected with individual conductors of a cable to be tested, this view showing the apparatus at only one end of the cable;

FIG. 3 is a diagrammatic view showing two switches of this invention placed in tandem relation and each connected with a different end of the cable and programmed by the same belt;

FIG. 4 is a view of the bottom face of the contact board shown on the switch of FIG. I;

FIG. 5 is a greatly enlarged sectional view of one of the contacts of FIG. 4, the section being taken on the line 5-5 of FIG.

FIG. 6 is a bottom plan view of the contact shown in FIG. 5;

FIG. 7 is an assembly view showing the positions of the contact board of FIG. 4 when in working relation with the selector drum of FIG. I and with the programming belt covering the selector drum as in FIG. I;

FIG. 8 is an enlarged fragmentary view of a part of the top surface of the selector drum shown in FIG. 1;

FIG. 9 is a top plan view of one of the contacts of the selector drum shown in FIGS. 1 and 8;

FIG. I0 is a sectional view taken on the line 10-10 of FIG.

FIG. 11 is a diagrammatic isometric view of the selector drum showing the way in which the contact carrier of the drum can be mounted to move toward and from the contact board to reduce friction and wear;

FIG. 12 is a sectional view through the drum, the section being taken on the line 12rl2 of FIG. I3; and

FIG. 13 is a sectional view taken along the section line 13I3 of FIG. 12.

DESCRIPTION OF PREFERRED EMBODIMENT FIG. I shows the selector switch with a contact board 15 having separate terminals 16 on its top surface for connection with the individual wires or conductors of a cable to be tested. FIG. 2 shows diagrammatically the manner in which separate conductors I8 of a cable 20 are fanned out and connected with the respective terminals 16 of the contact board. It is a feature of the preferred embodiment of this invention that the contact board 15 is detachable from the rest of the selector switch and the same switch can have a number of different contact boards so that the conductors of cables to be tested can be attached to the different contact boards before the contact board is assembled with the switch. Thus the connecting of conductors of the next cable can be performed while the switch of this invention is being used with another cable.

The switch has a frame or housing 24 which is shown in the drawing as part of an automatic cable tester, but this is not essential. Automatic cable testers are well known in the art and the switch of this invention can be connected with the cable tester in any desired manner. In the construction illustrated, the contact board 15 has a shaft 26 which is inserted into a complementary socket 28 in the frame or housing 24. The contact board 15 has another shaft 30 extending parallel to the shaft 26 and provided with a collar 32' at the end of the shaft remote from the contact board 15. The shaft 26 is in? serted into the socket 28 with the contact board sloping upward toward the shaft 30 so that the shaft 30 is located above a top surface 34 of the housing 24. After the shaft 26 is fully inserted into the socket 28, the contact board is rocked about the axis of the shaft 26 until the shaft 30 enters a socket 26 which is open at the top and which has an enlarged end 38 for receiving the collar 32. Since the collar 32 is of greater diameter than the socket 36, the collar holds the contact board in assembled relation with the housing 24.

A selector drum 40 is attached to a stationary axle 42 projecting from the housing 24 under the contact board 15. The drum 40 is attached to the axle 42 by a key 43 (FIG. 12). There is a sprocket 45 at each end of the drum 40. The circumference of each sprocket 45 is substantially flush with the surface of the drum. These sprockets 45 rotate on bearings on the drum.

For the present it is sufficient to understand that the sprockets 45 are rotated by a shaft 44 which is driven by power means 47 (FIG, 1) and an automatic positioner 46 in the housing 24. If desired, the sprockets 45 can be rotated manually and there is a position indicator 50 in the housing 24 for showing the position of the selector switch. The selector switch indicator 50 is preferably geared to the shaft 44 by gearing or other motiontransmitting connections correlated with the length of a belt 54 so as to indicate the position of the belt as the sprockets 45 are rotated intermittently. Sprocket openings 56 along the edges of the belt are engaged by teeth 58 projecting from the sprockets.

The contact board has a concave cylindrical face 60 which confronts the convex cylindrical surface of the drum 40 immediately below it and there are contacts on the face 60 and on the drum 40 which touch one another when not prevented from doing so by the belt 54. Openings 62 through the belt 54 are at selected locations in position to permit the contact of only those contacts on the contact board and the selector drum for the particular conductors which are to be tested at any one time.

The contact board 15 has four rows of terminals 16 and it has four corresponding rows of contacts 66 (FIG. 4) in the face 60. In the illustrated construction, the right-hand row of terminals 16 is connected with the right-hand row of contacts 66. The first terminal 16 of the right-hand row (FIG. 7) is shown connected with the first contact 66 of the right-hand row of contacts by a conductor 68 which is preferably a shielded conductor, as shown in FIG. 5 where the insulation 69 having electrically conductive shielding is grounded to pro tect the circuit of the conductor 68 from outside electrical influences. Similar shielding is used for the other conductors and wherever necessary to protect circuits from one another and from other outside influences.

The row of terminals I6 next to the right-hand row is connected with the third row of contacts 66 (FIG. 7); and the two rows of terminals 16 on the left side of FIG. 4 are connected with the second and fourth rows of contacts 66. Thus every terminal 16 connects with a separate contact 66 in the concave face 60 of the contact board 15.

FIGS. 5 and 6 are detail views of one of the contacts 66. In the construction illustrated, the contact 66 is made of metal, preferably phosphor bronze, and is inserted into a socket 70 in the face 60 of the contact board 15. There is an elastic plastic pad 72, preferably made of rubber, behind the contact 66 so that the contact 66 can yield when the rubber is compressed. The shielded conductor 68 extends through the pad 72 and touches the contact 66 to establish the circuit between the contact and the conductor.

The contact 66 is stiffly flexible and is bent slightly, to the curvature of the face 60 when inserted into the socket 70. The spring effect holds the contact against the end walls of the socket 70 to retain it in place and, if desired, the socket 70 can have a lip behind which the ends of the contact 66 will snap. In order to remove the contact 66 easily when it becomes worn and needs replacement, there is a slot 74in one end of the socket 70 for receiving a tool which can be used to pry the contact 66 out of the socket 70 to permit replacement by a new contact.

FIG. 7 is a view showing the way in which the contact board 15 fits over the selector drum 40 with the belt 54 located between the concave cylindrical face 60 of the contact board and the complementary confronting cylindrical circumference of the selector drum 40. There are four rows of contacts 76, as shown in FIGS. 1, 7 and 8, corresponding to the four rows of contacts 66 in the face 60 of the contact board 15 and these contacts 76 are spaced from one another so as to correspond exactly to the spacing of the contacts 66 of the contact board. In the preferred construction the contacts 76 are springpressed against the contacts 66 of the contact board 15, except when held apart by the belt 54. In the preferred construction, the contacts 76 move upward parallel to one another instead of along radial paths, but they can be radially located, if desired, provided that the radii correspond with the positions of the contacts 66 in contact board.

FIGS. 9 and 10 show the detail construction of one of the contacts 76. It will be understood that all of these contacts are preferably of similar construction. The contact 76 has a convex top surface 80 which is preferably rectangular in plan view, as shown in FIG. 9. The width of the surface 80, i.e., the vertical dimension in FIG. 9, corresponds with the width of the contacts 76 on the contact board 15; and the curve of the surface 80, best shown in FIG. 10, permits the edges of the openings through the belt to force the contact 76 downward when the contact moves under an imperforate portion of the belt. This is, in effect, a cam action.

The surface is the top of a cylindrical shell 82 which fits over a complementary shell 84. The shell 82 is open at its bottom and the shell 84 is open at its top. A helical compression spring 86, located in the shell 84, urges the upper shell 82 up ward and thus provides a spring contact.

The lower shell 84 is connected by a conductor 88 with an axially extending conductor 90 running along the full length of the selector drum 40 and connecting with all of the contacts 76 of one row of contacts. All of the contacts 76 of each row of these contacts are connected with a different conductor 90. In FIGS. 1 and 7 the four different conductors 90 are indicated by the

reference characters

90, 90a, 90b and 900. These conductors extend beyond the end of the selector drum 40 and into the housing 24 (FIG. I) where they join separate circuits leading to the automatic cable tester.

The shell 82 of each of the contacts 76 slides up and down in a cup which forms shielding 94 secured to a guide plate 96 to which other shielding 94 of all of the other contracts 76 is connected. Each of the conductors 90 extend through all of the shieldings 94 of one of the rows of contacts 76, and these conductors 90 are shielded where they pass from one shielding 94 to the next.

The plate 96 is located in a socket 98 (FIG. 7) in which the plate has limited radial movement. Circumferentially extending edges 100 of the drum 40 along both sides of the socket 98 overlap the edges of the guide plate 96 to limit its upward movement. Springs 102 hold the plate 96 upward against the edges 100 except when the plate is pushed down by the cams I06 (FIGS. 11- 13) carried by the sprockets 45 and cooperating with a follower 107 on each end of the plate 96. Whenever the sprockets 45 move angularly to shift the belt 54 from one position to the next programming position which brings a different group of openings 62 over the contacts 76, the cams I06 push the guide plate 96 down. For ordinary programming, each movement of the belt is for an angular distance equal to four times the space for each row of contacts 76 from the next row. Thus all of the belt openings over the contacts 76 during one test are replaced by new openings for the next test. Special programming can be worked out to use one or more of the rows of openings in the belt in successive tests and with such programming, the drum moves through a smaller angular movement.

FIGS. 12 and 13 show the way in which the sprockets 45 are driven by the shaft 44. Each of the sprockets 45 rotates on an end portion of the drum 40 as a bearing. There are gear teeth 109 on the inside of each sprocket and these gear teeth extend into circumferential grooves 110 in the drum. A portion 112 of the drum 40 on one side of each of the grooves 110 is removable to permit assembly and disassembly of the sprockets with the drum; and a nut 114 on the axle 42 holds the portion 112 against the end of the midpart of the drum.

The grooves 110 are cut through all the way to the hollow interior of the axle 42. Gears 116 on the shaft 44 mesh with the teeth 109, on the sprockets 45, at the locations where the grooves 110 extend all the way through the wall of the axle 42. Bearings 118 in the axle 42 support the shaft 44 and hold it against end play.

Whenever the shaft 44 is operated to shift the switch to its next test position, the gear teeth 109 drive the sprockets 45 and the rotary movement of the sprockets moves the cam faces 106 of the sprockets across the cam followers 107 at opposite ends of the plate 96. There is one cam follower 107 at each end of the plate 96 in the construction illustrated. The cams push the plate 96 down so that the contacts 76 move down away from the belt 54 so as to reduce wear during relative movement of the belt and contacts.

In using the switch of this invention, one switch can be connected with the conductors at one end of the cable as shown in FIG. 2, and a similar switch can be connected at the other ends of the conductors with a synchronous drive 124 for operating the program actuators of the two switches simultaneously. The invention can also be used by having two switches in tandem, as shown in FIG. 3 where the parts of the second switch corresponding to those of the first switch are designated by the same reference characters with a prime appended. The switches are connected to operate in synchronism and a common belt 54 can be used for both switches if programmed for such tandem use.

The preferred embodiment of the invention has been illustrated and described, and it is defined in the appended claims.

lclaim:

1. A selector switch for testing multiconductor electric cables, including in combination a contact board having separate terminals for connection with the individual conductors of a cable, a contact face on one surface of the board, a separate contact connected with each terminal and located on said contact face, a selector drum with contacts corresponding to the contacts of the contact face, conductors for connecting the contacts of the selector drum with a cable tester, and means for preventing selected contacts of the face from touching selected contacts of the drum, said means being a perforated shield movable to change the particular contacts that touch one another for successive tests.

2. The selector switch described in claim 1 characterized by the perforated shield being a belt with openings at selected locations movable into position to permit different selected contacts on different sides of the belt to touch one another.

3. The selector switch described in claim 1 characterized by the contact face of the contact board having a concave cylindrical face and the selector drum having a convex cylindrical face complimentary to the concave face of the board, and the perforated shield being a belt located between the cylindrical faces with perforations therethrough in register with selected contacts on the cylindrical faces and through which perforations the contacts of the cylindrical faces touch one another, said belt constituting the means for preventing contacts from touching one another.

4. The selector switch described in claim 1 characterized by the contact board being detachable from the rest of the switch so that the terminals of the contact board can be connected with the conductors of a cable at one time and the contact board can be assembled with the switch at a later time.

5. The selector switch described in claim 4 characterized by a frame with which the drum is connected, the contact board having a shaft that fits axially into a socket in the frame, a second shaft that moves into a second socket as the board swings about the axis of the first shaft, and a collar on the second shaft in position to hold the board connected with the frame.

6. The selector switch described In claim 1 characterized by the contact board having sockets in its contact face, and contact spring strips that bend to snap into the sockets and that can be removed from the sockets for replacement when worn.

7. The selector switch described in claim 1 characterized by the contact board having sockets in its contact face, contacts that fit into the sockets and that are removable therefrom for replacement when worn, and elastic elements in the sockets behind the contacts providing yielding moving of the contacts of the contact face when they are touched by other contacts of the drum.

8. The selector switch described in claim 1 characterized by the terminals of the contact board being in parallel rows, and the contacts located on the contact face and said contact board being in corresponding parallel rows and connected with the corresponding rows of terminals.

9. The selector switch described in claim 8 characterized by there being four rows of terminals and four rows of contacts, and the connectors between the different terminals and contacts being shielded from one another.

10. The selector switch described in claim 2 characterized by the contacts on the selector drum including assemblies that have a contact element which projects from the drum, resilient means holding the contact element in its projecting position, a sloping surface on the projecting portion of each contact element in position to cam the contact element inward against the pressure of said resilient means when the edge of an opening in the belt moves across the projecting contact element, all of said contact elements of the selector drum being electromagnetically shielded from one another.

11. The selector switch described in claim 10 characterized each contact element of the selector drum being a cylinder shell open at its lower end, a second cylinder shell open at its upper end and with which the first shell telescopes, the resilient ends being a helical spring substantially coaxial with the shells and compressed within the shells when the contact element is moved inward.

12. The selector switch described in claim 2 characterized by there being parallel rows of contacts on the contact ends of the board, and corresponding parallel rows of contacts on the selector drum in position to touch the contacts on the board when not prevented from doing so by said belt, all of the contacts in each row of the board being free of any electrical connection between them, all of the contacts of each row of the selector drum being connected to a common conductor for connection with a cable tester, shielding around each of the common conductors that connect the contacts of each row of contacts of the selector drum, and other shielding around each of the contacts of the selector drum.

13. The selector switch described in claim 2 characterized by cam means for moving the contacts of the board and the selector drum away from one another for each movement of the belt to reduce friction and wear of the contacts and the belt.

14. The selector switch described in claim 3 characterized by a sprocket rotatable about an axis, the belt having sprocket openings therethrough, teeth on the sprocket which project through the sprocket openings in the belt, means for rotating the sprockets intermittently through angles of movement to shift the belt into successive programming positions, the belt being of a length substantially greater than the circumferential extent of the drum and hanging loosely from the drum, the contacts of the drum being at the top thereof, and the cam means being connected with the sprocket for rotation as a unit therewith.

15. The selector switch described in claim 14 characterized by a position indicator connected with the sprocket and having motion transmitting connections correlated with the length of the belt for indicating the position of the belt in its program after each successive movement of the sprocket.