In re Griver (354 F.2d 377, 1966)

ALMOND, Judge.

David M. Griver appeals from the decision of the Board of Appeals affirming the rejection on prior art of claim 3 in appellant’s application entitled “Multi-Terminal Ground Stud.” The remaining claims in the application stand withdrawn from consideration as not readable on the elected species, viz. the ground stud of Figs. 1 and la, hereinafter reproduced.

Claim 3 reads as follows:

A multi-terminal stud for providing a common reference potential for electronic circuits mounted on a chassis, said stud comprising: an electrically conductive shank member having a smooth-surfaced central aperture therethrough for mounting the stud in an upright position on the chassis, said shank member having a counterbore at one of its ends for firmly mounting thereon the shank member of another stud; and an electrically conductive disc-shaped member at said one end thereof integral with and extending from said shank member, said disc-shaped member having holes therethrough spaced along an equipotential line thereon to provide equal values of resistance between said holes and the chassis, the low potential wires of the circuits being respectively inserted in said holes for connection to the stud thereat thereby to provide a common reference potential for the electronic circuits.

Figs. 1 and la of the preferred stud depict the following configurations:

Bored shank 10 is surmounted by outwardly extending flange 11. Holes 14, designed as receptacles for soldered wire connections are equidistantly spaced from the axis of the shank. These terminal holes are “positioned along an equipotential line which is * * * a circle.” The lower end of shank 10 bears against the chassis or metal ground support and is secured thereto by inserting a machine screw through bore 12 and an aligned hole in the chassis. Upper counterbore 13 receives the head of the screw or the lower end of a stacked ground stud. The application states that the “stud may be mounted on the chassis by putting a thread on the lower portion of the shank member and screwing it to the chassis.”

The references applied below are:

British Patent 783,545 September 25, 1957

Italian Patent 514,965 February 11, 1955

The British patent discloses an electrical feedthrough terminal assembly.

Pig. 2 of the drawing is reproduced below:

Coupling 18 includes a disc or plate 19 “formed on one side with a small boss 20 having an outside diameter considerably less than the diameter of the disc” 19. The disc and the boss are “centrally apertured and internally threaded for attaching the coupling to the threaded member 12.” Disc 19 “is formed around its periphery with a plurality of apertures 21 for receiving the ends of the wires” which are soldered to the disc. In assembling the terminal, the coupling 18 “is screwed onto the threaded member 12” so that the protruding end of member 12 “is level or slightly below the outer face 22 of disc 19 when the boss engages” a washer of the terminal. The resulting depression in disc 19 “is then filled with solder whereby the disc and stem of the terminal become one unit electrically.”

The patent states that one or more wires may be removed by the application of heat without disturbing the remainder or adversely affecting the electrical efficiency of the connection. It is further stated that the “coupling provides a simple method of providing separate soldered connections” which are “not affected by vibration and have a lower electrical resistance than a screw or nut connection * # * >9

The Italian patent discloses an electrical connection comprising plug and socket portions for telescopic stacking. The base connector may have a threaded extension rather than a plug for bolting through a mounted panel.

The examiner rejected the instant claim as unpatentable over the British patent in view of the Italian patent, finding that the British patent discloses every detail recited in the claim except that the bore of the stud is threaded and no counterbore is shown. The examiner noted that the Italian patent discloses a stud having a bore and a counterbore to receive a like stud therein and would therefore suggest to one skilled in the art provision for a counterbore in the British patent for mounting a stud therein and that it would be obvious to omit the screw threads in the bore if desired. With reference to the arrangement of the holes in the disc of the British patent, the examiner considered the arrangement symmetrical “with respect to both the periphery and the axis of the disc and that this is the obvious way of arranging a plurality of wire-receiving holes in a disc.”

In response to applicant’s contention that the wire-receiving holes 21 in flange 19 of the British patent are “so haphazardly arranged” as to provide materially different resistances between the holes and the chassis, the board stated that in its opinion the holes:

* * * appear to be arranged in a substantially equipotential line. While some of the holes appear to be larger than others, and assuming arguendo that is in fact the case, we point out that when the wires are inserted therein and the free space is filled with solder, the flange will be a solid conductive member. Therefore, it is not seen how any significant or even a noticeable difference in resistance would be present * * *. As to whether the bore of the shank of the stud is smooth surfaced or threaded is not, in our opinion, of patentable significance since it is a matter of common knowledge that articles of this nature may be supported either by direct threaded connection or by a bolt passing therethrough and through the supporting member and held in place by a nut or nuts.

With reference to tlr- matter of the counterbore, the board agreed with the examiner that the Italian patent would fairly suggest to one of ordinary skill in the art to provide the British'coupling with a counterbore to receive another stud in telescoping relation and that Ike difference in the structure j« s¡s % sj« H*

With respect to the opinion expressed by the Board of Appeals that the apertures (21) in the British Patent appear to be arranged in a “substantially equipotential line”, it is to be pointed out that this is not taught by the British Patent, nor can the spacing of the holes be adequately judged from Figures 1 or 2 therein. It is impossible, therefore, to positively confirm that the holes are, in fact, located along an equipotential locus from the axis of the terminal stem, as is taught by Appellant’s device. Accordingly, there is no evidence in the British patent to warrant the conclusion that this feature is an integral part of the British invention. On the contrary, as previously pointed out, the apertures (21) on the British terminal assembly are of unequal diameters, thereby preculding the establishment of true electrical equi-potentiality.

Furthermore, the British device was never intended to be a low-potential or page 1, lines 69-73, that “ * * * chassis ground termination, as is indicated by the wording of the British specification which clearly states at the terminal assembly 10 shown therein is intended for an electrical device, such as a transformer, a part of the wall of which is shown at 11. The wall is of any suitable insulating material * * demonstrates that the British device was intended as an electrical “tie-point” for use as a convenience of assembly, what is known as a feed-through terminal.

. The subject matter of appellant’s invention is set forth in his application as follows :

Electrical and electronic circuits generally have one or more points in these circuits connected to some common source of reference or ground potential. For this purpose, the above-referred to low potential points are customarily connected to the chassis upon which these circuits are mounted at different points thereon. However, in view of the fact that even an excellent conductor has some resistance between points on its surface, be it ever so small, the circuit connections to the chassis inherently have some ohmic resistance existing between them. As a result, current circulating between these points produces small potential differences or voltages between them which prevent the various points in the circuits from being connected to the same reference potential as intended. These differences of potential or, stated differently, this unbalance, may be amplified by the circuits and, therefore, may oftentimes cause erroneous circuit outputs.

Another technique customarily employed in the electronics arts is to mount a lug on the chassis and then connect all the low potential points in the circuits to this lug. However, although the above-mentioned unbalance is reduced, the use of a lug does not resolve the problem of providing a true reference potential. Furthermore, the use of a lug introduces a wiring problem in that each time the solder on the lug is melted to either connect or disconnect a wire, other wires soldered to the lug are also loosened.

It is, therefore, an object of the present invention to provide a multi-terminal stud that provides the same potential at each terminal connection.

It is another object of the present invention to provide a multi-terminal stud wherein electrical currents do not circulate between different terminal connections.

It is a further object of the present invention to provide a multi-terminal stud adapted so that the connection or disconnection of a wire will not affect the bonds between the stud and other wires that may be connected to it.

The present invention overcomes the above and other disadvantages of prior art reference potential connection devices by providing a stud having an equipotential line thereon to which low potential points in circuits may be connected. Multi-connections to the stud are facilitated by means of orifices spaced along the equipotential lino, one circuit connection for each orifice. In particular, the two specific problems mentioned above as being encountered among prior art devices are resolved since, first, the potentials at all connection points vary together and in any identical manner so that a common reference potential is at all times preserved and, second, the connecting or disconnecting of a wire at any orifice does not affect the wire connections at other orifices on the stud.

. The term “equipotential line,” as used in claim 3, is accepted terminology to describe a characteristic of an electrical circuit. It is not a “line” in the literal sense nor does it refer to any other well known geometric figure although it may in a given instance assume the locus of points described by a geometric figure. By definition, an equipotential line is a series of points all of which, in relation to a common point, are equal in electrical potential. When two points are said to be located on an equipotential line, the work necessary to carry a unit positive charge from the one point to the other is zero.

Appellant’s invention consists of a multi-terminal stud for providing a common reference potential for electronic circuits mounted on a chassis. The precise way in which the invention achieves a common reference potential for multiple terminals is to define the location of each terminal along an equipotential line. This is not made obvious in view of the references of record.