US3848958A

US3848958A - High density terminal strip

Info

Publication number: US3848958A
Application number: US00387153A
Authority: US
Inventors: W Kern
Original assignee: Teradyne Inc
Current assignee: Teradyne Inc
Priority date: 1973-08-09
Filing date: 1973-08-09
Publication date: 1974-11-19
Anticipated expiration: 1991-11-19

Abstract

A terminal strip for multiple electrical connections has an insulating support base, containing at least one row of terminals, angled up from the mounting plane to form an inclined terminal panel. The angled geometry reduces the area covered by the strip and by the conductors connecting to the strip. The angled geometry further allows easy access for making connections and increases the number of terminal sites. A preferred embodiment has two rows of terminals arrayed on a pair of mutually inclined terminal panels, and a mounting board is assembled to the terminal strip for gas-sealed attachment to an enclosed electronic device.

Description

United States Patent 1191 Kern [ HIGH DENSITY TERMINAL STRIP [75] Inventor: Walter Kern, Cohasset, Mass.

[73] Assignee: Teradyne,Inc., Boston, Mass.

[58] Field of Search 339/198 R, 198 C, 198 E, 339/198 G, 198 GA, 198 H, 198 J, 198 K, 198 8,198 P, 272 R, 272 A, 119

[11] 3,848,958 [451 Nov. 19, 1974 1,412,563 8/1965 France ..339/19so Primary ExaminerRoy D. Frazier Assistant ExaminerRobert A. I-Iafer Attorney, Agent, or Firm-Kenway & .Ienney [5 7] ABSTRACT A terminal strip for multiple electrical connections has an insulating support base, containing at least one row of terminals, angled up from the mounting plane to form an inclined terminal panel. The angled geometry reduces the area covered by the strip and by the con- [56] References Cited ductors connecting to the strip. The angled geometry UNITED STATES PATENTS further allows easy access for making connections and increases the number of terminal sites. A preferred 1,691,088 ll/l928 Starke 339/198 11 embodiment hasv two rows f terminals arrayed on a g i g pair of mutually inclined terminal panels, and a 3199'068 8/1965 s er 339/198 8 mounting board is assembled to the terminal strip for 3:454:836 7/1969 Nordeni 339/198 R gas-Sealed attachment to an enclosed electronic vice. FOREIGN PATENTS OR APPLICATIONS 968,689 3/1958 Germany 339/198 18 Claims, 4 Drawing Figures 3O 1s 34 K 5% 55 l 27 I6 27 |e-- |a 30b r U 1 16b 30b P t -48 Q 7% -20 m 7 4 n 2Oc1 I L 14 44 46 20G 4 44 14 PATENTEBuuv 1 91914 SHEET 10$ 2 BACKGROUND OF THE INVENTION This invention relates to improvements in electrical terminal strips of the type having screw-type terminals. More particularly, the invention provides a new configuration for sucha terminal strip which has numerous advantages including advantages in the density of connections and in the ease of making connections.

Terminal strips are frequently used to provide a convenient means of electrical connection between electronic equipment and external wire conductors. A typical commercial application is to connect a control computer to an automatic machine tool.

Conventional terminal strips generally have an elongated, flat piece of bakelite which supports one or two rows of terminal screws. Some models employ a metal tab or spade lug secured under the screw that either electrically links two terminal screws, or itself provides one or two male connecting sites. One or both ends of the lug can extend laterally from the bakelite strip or be angled up from the upper surface of the strip. It is also known in the art to extend the lug through the strip to provide a connecting site on the underside of the strip. To reduce arcing and inadvertent short circuiting between adjacent terminals and wires, an insulating bakelite wall is frequently interposed between adjacent terminals.

A principal disadvantage of these terminal strips is that wires connecting to the strip typically approach the strip from the side. This results in an inefficient utilization of the surface area near the terminal strip due to both the large area covered by the laterally projecting wires, and the necessarily wide spacing between adjacent terminal strips. These problems can be alleviated somewhat by angling the spade lugs up from the terminal surface. However, an efficient utilization of the available space is nevertheless restricted by the width of the strip itself and the necessity of allowing sufficient space between adjacent strips to connect and disconnect the wires conveniently.

Inconvenience in connecting wires and components to a conventional terminal strip is another disadvantage. In making a straightforward connection of a single wire tightened under the head of a terminal screw, a screwdriver or the wire can easily cause a short-circuit by contacting an adjacent terminal. A three wire connection to a single terminal is especially difficult since there are at most two convenient connection sites, one at the spadelug and the other at its corresonding terminal screw.

Still another disadvantage is that conventional strips are not readily adaptable to gas-sealed mounting. It is difficult to seal the terminal screws that penetrate the strip against the leakage of gases through the strip. Gas sealing is often desirable where, for instance, the strip is mounted on electronic control device and arcing relays in the device can ignite combustible gases, or other components can be damaged by corrosive gases.

Finally, terminal strips in the prior art do not provide a convenient surface for numbering or otherwise identifying the terminals. The flat surface of the strip and the surrounding mounting surface are usually obscured or hidden from view by the connecting wires.

SUMMARY OF THE INVENTION The terminal strip of this invention has one or more elongated non-conductive terminal panels, each containing a row of terminals, inclined about one longitudinal edge upward from the mounting plane.

This feature significantly reduces both the width of the terminal strip and the required spacing between adjacent strips, as compared with the prior art. A typical double row strip hitherto had a width of approximately one and a half inch, whereas a comparable strip according to this invention is one inch wide. Thus a density increase of fifty percent is achieved. In addition, the inclined geometry facilitates access to the terminals and encourages the approach of connecting wires in a direction perpendicular to the mounting surface,

thereby significantly reducing the spacing between adjacent strips still further. Also, the inclined terminal panel makes the underside of the panel accessible for additional connection sites at the nuts threaded on the terminal screws.

When an inclined plane terminal block of this invention is mounted on a flat, insulating board, gas-sealed mounting can be achieved by extending connection elements such as solder tabs or wire-wrap tails or tabs through the mounting board, sealing the board around the extending lugs, and using a gasket to enclose all of the free extending lug portions. Mounting screws are then inserted in the area lying outside of the gasket.

Thus a principal object of this invention is to provide a terminal strip having a high density.

Another object is to provide a terminal strip having convenient access to the terminals.

Still another object is to provide a terminal strip having additional connecting sites.

A further object is to provide a terminal strip capable of a gas-sealed mounting.

These and other objects and features of this invention will be apparent from the following detailed description and in conjunction therewith, the accompanying drawmgs.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 a pair of terminal strips indicated generally at 12, 12 are gas-seal mounted on an enclosed electronic device. The housing 14 of the electronic device is.cut away to show the portions of the terminal strip 12 which extend into the device and the details of the mounting. I

With reference to FIGS. 14, the terminal strip 12 has a terminal block 16 with a pair of mutually inclined terminal panels 18, a mounting board 20, and two rows of arrayed terminal screws 22 fastened through the terminal panels 18. The terminal block 16 is an elongated, non-conductive strip having a generally Y-shaped cross section (FIG. 2). The base portion 16a'of the block 16 is generally flat and parallel to the plane of the mounting surface 14. A neck portion 16b extends upward from the base portion 160. The two terminal panels-18 branch from the top of the neck portion 1612 so that each forms an angle with the mounting plane, this angle preferably is 45, as illustrated, so that each panel is at right angles with respect to the other. Each illustrated panel 18 extends for approximately 4/10 inch from the neck. The junction of the panels 18 and the neck 16!) is reinforced by a central ridge l6c.formed directly above the junction.

Each terminal panel 18 contains a row of one-eighth inch diameter terminal holes 24 that receive the terminal screws 22. The bore of the holes 24 is perpendicular to the panel 18, that is, is angled relative to mounting surface 14 exactly inversely to the relation of the panels 18, to allow a flush contact between the screws 22 and the panel 18. The holes in one panel 18 are symmetrical with and aligned opposite to the corresponding holes in the second panel 18.

Transverse insulating and barrier walls 26 separate opposed pairs of

terminal screws

22, 22 from longitudinally adjacent pairs of terminal screws 22, as FIG. 3 shows. The illustrated walls 26 extend downward from a line 26a (FIG. 2) between the outer edges of the panels 18 to the ridge 160. The junction between the wall and the ridge is curved since the ridge surface it itself curved on a radius concentric with the holes 24 (FIG. 3).

A lower barrier wall 27 projects like a ridge from the lower surface of each panel 18. Each illustrated wall 27 is oppositely in line with an upper wall 26. The lower walls 27 separate portions of adjacent terminal screws 22 that extend through the panels 18. The walls 27 extend in length from an outermost trimmed corner 27a to the plane of the base portion 16a. The

walls

26 and 27 serve to reduce arcing and short circuiting between adjacent terminals, due either to the proximity of conductors, or to the inadvertent slipping of a screwdriver or other tool. The walls also contribute to the overall structural strength and stability of the terminal block 16 and serve to define the ends of the block.

Arcing and short circuiting are also reduced by the ridge 16c and the inclined geometry characteristic of this invention. These features combine to reduce contact between oppositely and longitudinally adjacent terminals. If an attached conductor extends from under a screw head, or if a screwdriver slips off a terminal screw, it is restrained by the ridge 160 before touching the opposed terminal. The curved shape of the ridge 16c also serves to guide a screwdriver when it is en-' gaged in a screwhead. The inclined geometry of the panels 18 aids in providing a relatively deep wall 26 between longitudinally adjacent terminals and in providing clearance under the panels 18 for the insulating walls 27.

strained by a nut 28 threaded on the portion of the screw extending through the terminal panel 18. As shown, the walls 27 restrain rotation of the nut, thereby eliminating the need for pliers or a wrench when tightening or loosening the screws 22. FlGS. 1, 2 and 4 also illustrate a terminal utilizing a flat lug 30 consisting of a metal strip or tab attached to a screw 22 through a hole 30a (FIG. 4) in the body of the lug. The lug 30 has an assembly portion 30b held against the underside of the panel 18 by the nut 28. The lug portion 30b fills the space between adjacent lower walls 27 except at its lower edge where it tapers to approximately one-fou rth of its width. This narrow lower lug portion 306 extends downwardly, initially in contact with the neck 16b, for connection to external circuitry within the housing 14. At the other, upper edge of portion 3%, the lug is bent at a 45 angle so that an upper lug portion 30a' is in a direction normal to the mounting surface 14, as shown in FIG. 2. The portion 30d has a reduced width end to seat a conventional female connector 32 with an attached wire conductor 34 (FIGS. 1 & 4).

The illustrated flat lug 30, as described, facilitates several objects of this invention. First, the upright direction of the portion 30d permits a straight-in connection of conductors rather than the side approach common to conventional terminal strips. This in turn allows adjacent terminals strips 12 to be more closely spaced (FIG. 1) since less area between the strips is occupied by laterally projecting wires. Also less clearance space is needed to make a straight-in connection. Second, the lower lug portions 30c provide a means for either plugin, wirewrap or solder electrical connection within the housing 14, as illustrated by connection to a printed circuit card. As described hereinafter, the portions 300 can provide such connection means inside of a gas sealed housing.

Third, the additional, connection sites on the

lug portions

30c and 30d, and the accessibility of the panel underside at each nut 28 as a connection site, allow multiple direct and independent connections to a single terminal. This feature is illustrated in FIGS. 2 and 4 which shows one wire 34 secured under a terminal screw 22, two

further wires

34, 34 secured under the nut 28, and lug portion 30d available for a fourth wire, not shown. Thus, the upper face of each panel provides plural connection sites, each of which can receive, under the screw head, (i) a wire and/or (ii) lugs or terminals such as of the spade or fork type. The underside of each panel provides a like plurality of connection sites, each of which can receive, under the nut, (i) at least two separate wires, one on each side of the screw threaded onto the nut, (ii) an appliance or automotive type female terminal as illustrated on the lug portion 30a, and- /or (iii) lugs or terminals as of the spade or fork type. Since the nut is precluded from rotation, wires seated under it are held fast and are not subject to dislodgement when the screw is tightened. It should now be understood that the inclined surface of this invention has the advantage of increasing the number connecting sites by making the panel underside accessible.

As shown in FIGS. 1-4, the illustrated embodiment of this invention also has a generally flat, rectangular mounting board 20 attached by assembly screws 36 (FIG. 4) to the terminal block 16 at the base portion 16a. With reference to FIG; 3, the board 20 extends beyond the block 16 only the distance required for the mounting holes 38, by which the assembled terminal strip 12 and board are mounted, for example, to the device housing 14. As with the terminal block 16, the mounting board 20 can be molded from a poly aryl sulfone such as is marketed by the Minnesota Mining and Manufacturing Company under the trade designation Astral 360 or an insulating material having equivalent molding, dielectric and flexing characteristics. An embossed portion 200 extends along the longitudinal axis of the board 20 protruding downward from the bottom surface of the board 20. The embossment 20a extends in length to the ends of the block 16 and, in width, to

the points of contact between the board 20 and the walls 27. The embossment serves to give the board extra structural rigidity. Also, it lends support to the lug portions 300 that are molded with the board 20. i

Four assembly holes 40 (FIG. 3) in the mounting board 20 receive the assembly screws 36. Each hole 40 is counter bored on the top surface to receive a small rubber O-ring 41 for effecting a gas-tight seal around the assembly screws. A number of small rectangular holes 42 are also indicated in FIG. 3. These holes receive corresponding lugs portions 300 if the terminal strip is manufactured without the lugs c sealed in the mounting board.

A gland 44 of generally rectangular cross-section is formed in the bottom surface of the board 20 so as to encircle the embossment 20a and all of the projecting connecting sites 30c, but excluding the mounting holes 38. The gland 44 receives a sealing member illustrated as a large rubber O-ring 46 whose diameter slightly exceeds the depth of the gland. In the mounting arrangement shown in FIGS. 1 and 2, the O-ring 46 provides means to gas-seal the interior of the housing 14 from the environment while simultaneously introducing the connection sites 300 into the interior of the housing. Mounting is secured by mounting screws 48 which pass through the mounting holes 38 into the housing 14.

Inside the housing 14 of the electronic device, a circuit element such as a printed circuit card 50 (FIG. 2) having conductive elements 52 on its surface can be conveniently attached to the terminal strip 12 by means of mounting cars 54 (FIGS. 1, 2 and 4) extending from the embossment 20a. A simple means of attachment, shown in FIG. 2, consists of a screw 56 that passes through the printed circuit card 50 and threads into a tapped hole in the ear 54. Suitable receptables, not shown, can be provided on the printed circuit card 50 for plug-in or solder connection with the lug portions 30c.

As illustrated in FIG. 3, the portion of the mounting board 20 that extends beyond the terminal block 16 serves as a convenient location for affixing numerals 60 to identify corresponding terminal positions. Due to the novel features of this invention, wire conductors approach the strip 12 from above and do not conceal the identifying numerals 60.

The illustrated embodiment of this invention offers significant advantages in the utilization of the mounting surface on the housing 14. The connecting sites provided by the screws 22 and the lug portions 30d are an inch or less apart, in contrast to a separation of A2 inch in previous terminal strips. The strip geometry and ease of access also allow the close spacing of two or more strips (FIG. 1).

Various modifications of the invention will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Such modifications are intended to fall within the scope of the appended claims.

Having thus described the invention, what is claimed is:

1. In an electrical terminal strip having at least two rows of connection sites arrayed on an elongated insulating base member which has a generally planar mounting surface facing in a first direction, each said connection site including an electrical terminalforming threaded element, the improvement comprising panel means of electrically insulating material on said base, said panel means carrying said rows of said connection sites and having a first surface at which said sites are accessible for electrical connection and for adjustment of said threaded element, said first surface facing away from said first direction and being inclined relative to said mounting surface, and said panel means having a second surface facing toward said first direction and being located intermediate said mounting surface and said first surface, and carrying at said second surface a row of further connection sites that are accessible for electrical connection.

2. In a terminal strip according to clalim 1, the further improvement wherein said first and second surfaces are substantially parallel, whereby they are substantially identically inclined relative to said mounting surface.

3. In a terminal strip according to claim 2, the further improvement wherein a single threaded shaft member forms said threaded element in a site on said first surface and also in a site on said second surface.

4. In a terminal strip according to claiml, the further improvement wherein said inclination is in the order of forty-five degrees.

5. In an electrical terminal strip according to claim 1, the further improvement comprising further panel means of electrically insulating material on said base and carrying further connection sites, said further panel means having third and fourth surfaces at which said further sites are accessible, said third surface facing away from said first direction and being inclined relative to said mounting surface and inclined relative to said first surface to define a Vee configuration therewith, said fourth surface being opposite to said third surface and intermediate said mounting surface and said third surface.

6. In an electrical terminal strip according to claim 1, the further improvement wherein said connection sites are arrayed along the elongation of said base member and said inclination of said first surface relative to said mounting surface is about said elongation of said base member.

7. In a terminal strip according to claim 1, the further improvement comprising a plurality of connecting tabs, each of which is engaged with one said threaded element and has a first portion extending from said panel substantially opposite said first direction, and a second terminal portion extending through said base member.

forming threaded element, the improvement comprising a panel means of electrically insulating material mounted on said base, said panel means having first and second substantially opposed surfaces, said panel surfaces being spaced away from said mounting surface and each carrying a row of said connection sites that are accessible for electrical connection, said first surface facing in a second direction away from said first direction and inclined relative to said mounting surface, and said second surface facing at least partially in said first direction, and also being inclined relative to said mounting surface.

9. In an electrical terminal strip according to claim 8, the further improvement wherein said accessible connection sites arrayed on said first panel surface are in register with said accessible connecting sites arrayed on said second panel surface.

10. A terminal strip comprising, in combination,

an electrically insulating mounting board,

an electrically insulating terminal block secured to said mounting board, said mounting board and said block having parallel longitudinal axes, said terminal block having a pair of terminal panels oppositely and equally inclined about their longitudinal axes relative to said mounting board,

a plurality of terminal screws serially arrayed on said mounting board.

11. A terminal strip as defined in claim 10 in which said second terminal portions pass through said mounting board within gastight seals therewith.

12. A terminal strip as defined in claim 11 further comprising gasket-like sealing means on the surface of said mounting board opposite to said terminal block, said sealing means encircling the passage of all said second terminal portions through said mounting board.

13. A terminal strip as defined in claim 10 in which each said panel is inclined by 45 relative to the plane of said mounting board.

14. A terminal strip as defined in claim 10 further comprising connection means for removably and replaceably securing said terminal block to said mounting board.

15. A terminal strip as defined in claim 10 in which said mounting board includes a central, elongated embossment opposite to said terminal block, and in which said second terminal portions extend through said embossment.

16. A terminal strip as defined in claim 10 in which said terminal screws extend through said panels to provide a plurality 'of accessible connection sites on opposed surfaces of each of said panels.

17. A terminal strip as defined in claim 10 in which said second terminal portions are adapted to electrically connect to a printed circuit board.

18. A terminal strip as defined in claim 17 further comprising means for mounting said printed circuit board insaid electrically connected state.

Claims

1. In an electrical terminal strip having at least two rows of connection sites arrayed on an elongated insulating base member which has a generally planar mounting surface facing in a first direction, each said connection site including an electrical terminal-forming threaded element, the improvement comprising panel means of electrically insulating material on said base, said panel means carrying said rows of said connection sites and having a first surface at which said sites are accessible for electrical connection and for adjustment of said threaded element, said first surface facing away from said first direction and being inclined relative to said mounting surface, and said panel means having a second surface facing toward said first direction and being located intermediate said mounting surface and said first surface, and carrying at said second surface a row of further connection sites that are accessible for electrical connection.

4. In a terminal strip according to claim 1, the further improvement wherein said inclination is in the order of forty-five degrees.

8. In an electrical terminal strip having at least two rows of connection sites arrayed on an elongated insulating base member which has a generally planar mounting surface facing in a first direction, each said connection site including an electrical terminal-forming threaded element, the improvement comprising a panel means of electrically insulating material mounted on said base, said panel means having first and second substantially opposed surfaces, said panel surfaces being spaced away from said mounting surface and each carrying a row of said connection sites that are accessible for electrical connection, said first surface facing in a second direction away from said first direction and inclined relative to said mounting surface, and said second surface facing at least partially in said first direction, and also being inclined relative to said mounting surface.

10. A terminal strip comprising, in combination, an electrically insulating mounting board, an electrically insulating terminal block secured to said mounting board, said mounting board and said block having parallel longitudinal axes, said terminal block having a pair of terminal panels oppositely and equally inclined about their longitudinal axes relative to said mounting board, a plurality of terminal screws serially arrayed on said inclined panels, and a plurality of connecting tabs, each of which is engaged with one said terminal screw and has a first portion extending from said panel in a direction substantially normal to said mounting board, and a second terminal portion extending through said mounting board.

13. A terminal strip as defined in claim 10 in which each said panel is inclined by 45* relative to the plane of said mounting board.

16. A terminal strip as defined in claim 10 in which said terminal screws extend through said panels to provide a plurality of accessible connection sites on opposed surfaces of each of said panels.

18. A terminal strip as defined in claim 17 further comprising means for mounting said printed circuit board in said electrically connected state.