Background of the Invention
[0001] This invention relates to coaxial connectors and more particularly, to selectively
insulated coaxial connector housings.
[0002] Present day computer terminals are typically interconnected by means of coaxial cable
for transmitting and receiving information to and from, for example, main frame computers,
or other terminals. Typically, the interconnections are effected by means of shielded
coaxial cables which are connected at terminals thereof by T-shaped shielded coaxial
connectors, typically of the BNC-type as well known to those of ordinary skill in
the art.
[0003] As also well known, such coaxial connectors are often subject to interference especially
when terminals are exposed and disposed adjacent electrical equipment, power lines
or metal walls which affect signals being transmitted through the coaxial cable. Moreover,
while providing a shielding effect, the outer housing of the connector while grounded
to the shields of the coaxial cable and/or other like shielding elements, are often
subject to contact with a separate external ground which can result in a ground loop
which will in turn detrimentally affect signals being transmitted through the coaxial
cable by disrupting the shielding.
[0004] In the past, one attempt to avoid these problems has been to insulatively isolate
the T-shaped coaxial connectors, for example, by use of a cover boot such as is disclosed
in U.S. Patent 4,538,869. While generally serving satisfactorily for ensuring that
the T-shaped coaxial connector, preferably a BNC-type connector is held in a fixed
position and prevented from establishing external separate grounds different from
the grounding to the shields of the coaxial cable, such boots are typically cumbersome
to use and oftentimes, due to the fact that it is a separate element which is enclosed
about the T-shaped connector, it is of ten the case that the user of a computer system
will forget to place the boot thereon, thereby exposing the connection to the risk
which the boot is intended to avoid. Accordingly, in accordance with the invention,
a coaxial connector is provided which does not require the use of separate elements
to ensure against extraneous grounds occurring while at the same time avoids such
extraneous grounds from being established in use in a computer system.
SUMMARY OF THE INVENTION
[0005] In accordance with the invention, there is provided an improvement in a coaxial connector,
in one aspect a T-shaped coaxial connector of the type having a conductive outer housing
for grounding the outer housing to provide shielding for conductors interconnected
by the connector. Typically, such conductors are in the form of shielded coaxial cables
of the type well known to those of ordinary sk.ill in the art which have shielding
braids to which the shielding outer housing of coaxial connectors are connected to
maintain shielding. The improvement resides in that the connector is selectively coated
on at least a portion of the outer housing thereof, which -is exposed in an assembled
state, with a non-conductive material for preventing inadvertent electrical contact
with other systems or earth grounds, whereby undesired ground loops are avoided thereby
preserving the integrity of communications being transmitted through coaxial cables
interconnected by the connectors.
[0006] In another aspect, the coating is provided of a thickness sufficient to provide electrical
insulation. Typically, the coating is of the type which has been deposited by conventional
electrostatic spraying and subsequent heat curing. More preferably, the coating is
one of a plastic material or an insulative epoxy material. Even more preferably, the
coating is one of nylon, tetrafluoroethylene polymer or rubber coating.
[0007] In still another aspect the connector comprises a female connector portion leading
into a dual male connecting portion off of a T wherein the coating is selectively
applied only to the outer surfaces of the female connecting portion and other portions
of the connection which are exposed when all portions of the connector are in a connected
condition to other elements such as coaxial cables. In a still more preferred aspect,
the connector is a BNC-type connector.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Having briefly described the invention, the same will. become better understood from
the following detailed discussion taken in conjunction with the appended drawings
wherein:
Figures 1-3 show sequentially a prior art structure employed with a conventional BNC
coaxial T-shaped connector shown being assembled about the connector which includes
cables connected thereto for the purpose of providing an insulative cover to the conductive
shielding outer housing of the BNC connector;
Figure 4a shows in perspective view a preferred embodiment of a T-shaped connector
housing in accordance with the invention;
Figure 4b shows in perspective view preferred embodiment of a cable terminating BNC-type
connector assembled to a cable, in accordance with the invention; and
Figure 5 shows in perspective view the preferred embodiment of the connector housing
in accordance with the invention shown with the BNC connector connected to three coaxial
cables, and wherein the connectors or terminating BNC portions of the coaxial cable
are modified as in Figure 4b to be compatible with the features of the invention as
shown in Figure 4a to provide the resultant advantages thereof.
DETAILED DISCUSSION OF THE INVENTION
[0009] As discussed previously, Figures 1-3 show the prior art means for preventing shielding
coaxial connectors, including T-shaped connectors, and especially BNC-type connectors,
which include a conductive housing, from being connected to a separate external ground
which would disrupt the shielding effect provided thereby. This means, as shown, generally
comprises a two-part housing 1 including an upper part 5 and a lower part 3 configured
for receiving and holding the connector 11 therein. The housing includes a connector
support portion 7 which secures the connector within the housing 1. Typically, as
shown in Figure 2, the connector is then connected at two female portions or jacks
19 including engaging lugs 21 to male receiving BNC-type connector portions or plugs
15 which are connected respectively for terminating corresponding coaxial cables 13.
Likewise, the male portion or plug 17 of the BNC-type T-shaped connector is engaged
to a female connector or jack portion which is attached for terminating a like coaxial
cable 13. Once the connections are established, the housing is closed upon itself
and the top and bottom parts 5 and 3 engaged together by means of latch 9 generally
shown in the drawings to be placed in a closed configuration as shown in Figure 3.
[0010] Although generally avoiding inadvertent external grounds from being established with
the connector housing 11 and which disrupt shielding, the prior art boot 1 which is
typically made of an insulative material is generally cumbersome to use, and it is
often the case that the user forgets to place it on the connector 11 once the unit
is assembled.
[0011] In accordance with the invention as shown in Figure 4, the requirement of a separate
housing 1 as taught in the prior art, and of which Figures 1-3 are illustrative of
the boot or housing disclosed in U.S. Patent 4,538,869 to Richards which has been
previously discussed, is avoided.
[0012] More particularly, the connector housing 11 and 15 as shown in Figures 4a and 4b
in accordance with the invention is selectively coated at a region 23, in the case
of Figure 4a, with an insulative material. More particularly, preferably as shown
in Figure 4a, the insulative material region 23 encompasses the male connector portion
or plug 17 of the BNC-type connector 11 as well as the middle of the T which leads
into the two female portions or jacks 19 which include engaging lugs 21.
[0013] As shown in Figure 5, when assembled to three coaxial cables 13, the female connector
portions or jacks 19 will be engaged to the male terminating BNC-type connector plugs
15 for the cables 13 which are shown in Figure 4b, and which as modified for use with
the invention are also selectively coated with a non-conductive material on the exposed
portions as illustrated. The non-exposed portions are connected to the cable 13 braid
to maintain shielding and are not coated with the insulative material. As shown in
Figure 5, the entire assembly then has the exposed connector housing parts completely
coated with insulative material so that inadvertent separate external grounds disrupting
the shielding are avoided.
[0014] With respect to the details of the interior of the T-shaped connectors themselves
as well as the terminating connector assemblies, these are conventional in nature
as will be readily apparent to those of ordinary skill in the art and are generally
identified as BNC-type connectors and connector assemblies. With respect to the coating
itself, this is typically applied by conventional spraying, preferably highly charged
electrostatic spraying method as well known to those of ordinary skill in the art
with a subsequent curing in an oven. The connector housing 11 is masked prior to spraying
and then the spraying is conducted. As noted, such spraying is well known to those
of ordinary skill in the art of plastic coating technology, and the thickness of the
coating need be only sufficient to provide the necessary insulative effect, typically
1-2 mils.
[0015] With respect to the materials employed to provide the coating, these can be a number
of materials among which are included tetrafluoroethylene polymer commercially available
under the trade name Teflon, other plastic materials as well as insulative epoxy materials.
In a more specific aspect, the coating can be a nylon coating, a rubber coating or
the like as will be readily apparent to those of ordinary skill in the art. The same
coating techniques and coatings are applied to the termination female connectors 15
of cable assemblies 13 to be connected to the connector 11.
[0016] Having briefly described the invention, what applicant considers the invention is
defined in the appended claims in a manner not intended to limiting. As will be readily
apparent, other equivalent materials can be substituted as well known to those ordinary
skill in the art without departing from the scope of the invention.
1. In a coaxial cable terminating coaxial connector of the type having a conductive
outer housing for grounding the outer housing to a shield of the cable to provide
shielding for conductors of the cable, the improvement wherein said connector is selectively
coated on a portion of the outer housing which is exposed when the connector is connected
to a coaxial cable, with a non-conductive material for preventing inadvertent electrical
contact with other systems or earth grounds whereby undesired ground loops and detrimental
effects on shielding are avoided.
2. A connector as in claim 1 wherein said coating is of a thickness sufficient to
provide electrical insulation.
3. A connector as in claim 1 wherein said coating is of the type which has been deposited
by electrostatic spraying and subsequent heat curing.
4. A connector as in claim 1 wherein said coating is of a plastic material.
5. A connector as in claim 1 wherein said coating is of an insulative epoxy material.
6. A connector as in claim 1 wherein said coating is a nylon coating.
7. A connector as in claim 1 wherein said coating is a tetrafluoroethylene polymer
coating.
8. A connector as in claim 1 wherein said coating is a rubber coating.
9. A connector as in claim 1 comprising a male connector portion.
10. A connector as in claim 9 wherein said connector is a BNC-type connector.
11. A connector as in claim 1 wherein said connector is a T-shaped coaxial connector.
12. A connector as in claim 10 wherein said connector is a T-shaped coaxial connector.
13. A connector as in claim 4 wherein said connector is a T-shaped coaxial connector.
14. A connector as in claim 13 wherein said connector is a BNC-type connector.