US 3525056 A
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United States Patent US. Cl. 333-22 8 Claims ABSTRACT OF THE DISCLOSURE A coaxial self-terminating outlet for a signal carrying coaxial cable such as a drop line from a CATV transmission line. The outlet is comprised of a coaxial jack onto which connects a mating male connector attached to an antenna lead, and a terminating mechanism. The terminating mechanism is comprised of a terminating resistor connected to a spring contact element biased into electrical contact with the center conductor of the signal carrying cable. When the antenna lead is disconnected from the outlet, the center conductor of the signal carrying cable is electrically connected to ground by the spring contact and the resistor, so that the impedance of the terminated outlet matches the impedance of the signal carrying cable.
The terminating resistor is disconnected from the center conductor when the mating male connector is plugged into the jack, and after electrical connection of the cables. This disconnection is accomplished by an actuating pin which bends the spring contact away from the center conductor and into ground contact. The actuating pin is attached to an actuating ring which rides around the outlet jack so that as the male connector is moved onto the jack, it displaces the supporting ring and attached actuating pin to break the terminating contact.
BACKGROUND The invention is in the field of fittings for high frequency transmission lines, and has particular application to the terminating of signal carrying drop lines associated with the distribution of Community Antenna Television (CATV) signals.
In the distribution of CATV signals a multitude of outlets must be provided, all of which are fed by a main signal carrying transmission line. Less than all of these outlets may be connected to receivers at a given time. In the absence of an impedance matched termination such unused outlets would greatly reduce the efficiency of the distribution system.
Prior to the present invention it has been necessary to manually terminate each outlet when not in use. Aside from the labor involved there was no assurance that a subscriber would not disconnect his receiver and leave his terminal open.
It is, therefore, an objective of this invention to provide a self-terminating outlet which will eliminate the need for manual termination of an outlet when not in use, and to provide an outlet which terminates the signal carrying cable in its characteristic impedance at all times when not in use.
Another object of this invention is to provide a terminating element for a signal carrying coaxial cable outlet which will terminate the primary cable upon disconnection of the secondary cable, but prior to the breaking of electrical contact therebetween.
A further objective of the invention is to provide a terminating element the terminal ends of which will be connected to ground when disconnected.
Another and still further objective of the invention is to 3,525,056 Patented Aug. 18, 1970 ice provide a signal carrying outlet in which the signal carrying element will be automatically connected and disconnected to a matching impedance upon withdrawal or insertion of the connecting element.
SUMMARY Briefly, the invention is an outlet terminal for a signal carrying coaxial cable, having a tenminating element associated therewith which connects the center conductor of the signal carrying cable to a matching impedance whenever the outlet is not in use. The outlet is comprised of a jack connected to the signal carrying cable and adapted to receive a mating male connector. A contact element connected to ground through a resistor is biased into contact with the center contacting element of the coaxial outlet so that the signal carrying cable is terminated in its characteristic impedance when the mating connector is not connected to the outlet jack. The contact is displaced from the center conducting element when a connection is made to the outlet, by the action of a pin attached to an actuating ring which slides along the body of the outlet jack. As the mating connector is slid onto the outlet jack it displaces the actuating ring and the attached pin; the pin engages the spring contact moving it out of contact with the center conductor and into contact with the grounded outer cover of the outlet.
The contact element is shaped to cause wiping contact with the center conducting element of the connector.
The invention has the advantage of providing automatic and impedance matching termination of a CATV drop line or the like when its associated outlet is not in use, eliminating the losses associated with an open line and the need for any manual termination of the outlet when not in use. The terminator requires no modification of the male connector for a standard coaxial outlet jack. The invention is simple in construction and operation rendering it inexpensive and reliable.
The invention has the additional advantage of being easily incorporated in existing outlets.
All of the objects, features and advantages of this invention and the manner of attaining them will become more apparent and the invention itself Will be best understood by reference to the following description of the in vention taken in conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partially cut away side view of the outlet of the invention with its mating connector disengaged therefrom.
FIG. 2. is a partially cut away side view of the outlet of the invention with a mating connector engaged thereon.
FIG. 3 is a partially cut away back view of the outlet of the invention taken along line 3-3 of FIG. 1.
FIG. 4 is a partial front view of the outlet of the invention taken along line 4-4 of FIG. 1.
DETAILED DESCRIPTION The outlet of the invention illustrated in FIGS. 1-4 is mounted upon a base plate 1. A right-angled coaxial connector housing 2 is attached to base 1 by a bracket 3-. A leg 4 of the housing 2 extends through an aperture 5 in plate 1. A coaxial terminal 6 for connection to a signal carrying drop line is mounted within and extends from the extremity of a leg 7 of body 2 which lies parallel to plate 1. A quick disconnect jack -8 for connection of a coaxial subscriber cable is mounted within and extends from the extremity of leg 4 which extends through the base plate 1.
Disposed coaxially within legs 4 and 7 are center conducting elements 9 and 9a connected respectively to the center contacts (not shown) of terminal 6 and jack 8. The end 10 of leg 7 opposite terminal 6 is open providing 3 access to center conducting elements 9 and 9a at their point of contact.
A block of insulating material 11 mounted on plate 1 adjacent the open end 10 of leg 7 supports a spring contact 12 in position for contact with center conducting element 9. Spring contact 12 is a thin and narrow strip of resilient conductive material to reduce its capacitance and minimize any disturbance its presence might cause Within the connector. Contact 12 is electrically grounded through a resistor 14 connected to plate 1 and having a value selected to terminate the drop line in its characteristic impedance when contact 12 is in contact with conducting element 9.
Referring to FIG. 2, when a subscribers cable is plugged into jack 8, arm 12b of contact 12 is disconnected from center conducting element 9, and pushed into contact with housing 2 by the action of an actuating pin 15. Actuating pin 15 is a rigid length of non-conducting material and is attached to, or may be an integral extension of an actuating ring 16 (see FIG. 4). Ring 16 fits around and slides along a cylindrical body 17 of jack 8. Actuating ring 16 is displaced toward plate 1 by the mating male connector 18 of jack 8 as it is slid onto body 17 (see FIG. 2), and when so displaced, pushes pin 15 against arm 12b breaking the contact of arm 12b with center conducting element 9, and forcing arm 12b into contact with grounded body 2 of the outlet.
Referring to FIGS. 3 and 4, pin 15 is guided by a slot 19 in a portion of insulating block 11 which extends through aperture in plate 1. Block 11, pin 15 and ring 16 are preferably made of a self-lubricating dielectric material to eliminate any binding of the mechanism. Freedom of movement of the mechanism upon disconnection of connector 18 from jack 8 is of particular importance, as upon removal of connector 18, pin 15 and ring 16 are forced out by the spring action of contact arm 12b as it returns to contact with center conducting element 9.
In the illustrated embodiment of the invention, spring contact element 12 employs a combination of torque and bending forces to maintain its position in contact with conducting element 9, and to force the withdrawal of actuating pin 15.
Referring to FIG. 3, spring contact 12 is a dog-legged strip of resilient conducting metal. One arm 12a of the strip is attached to insulator 11 by an insulated rivet 13, in such a position that the other arm 12b is in contact with, and based against, the junction of center conducting elements 9 and 9a.
When connector 18 is disconnected, arm 12a lies virtually flat upon block 11, and contact is maintained between arm 12b and conducting element 9 substantially by the force created by the bending of arm 12b alone. When connector 18 is connected to jack 8, actuating pin 15 exerts a force upon arm 12b at a point close to its junction with arm 12a. As a result of this, the free end of arm 12a is raised from block 11 and twisted, which reactions store tensions within contact 12. Furthermore, as illustrated in FIG. 2, the tip 12c of arm 12b is bent up to make contact with housing 2 prior to the complete insertion of pin 15. As a-result of this construction, when pin 15 is fully inserted by the action of connector 18, arm 12b is bowed, creating a substantial spring force which will initially act to expel pin 15 when connector 18 is disconnected. This design permits the maximum utilization of the resilience of spring contact 12, which assures effective operation of the contact over a long period of time. That portion of spring contact 12, designated 12d, which actually makes contact with the junction of center conductors 9 and 9a, is angled to make a wiping contact when brought into contact therewith. This wiping eifect enhances the electrical contact between the two by brushing away any oxidation or foreign matter that could collect upon a single contact spot. This configuration also allows for variations in the contour of the soldered joint between center conductor elements 9 and 9a.
.As illustrated in FIGS. 1 and 3, spring contact 12 is mounted upon block 11 so that when in contact with center conductor 9-9a, arm 12b falls substantially upon the axis of arm 9 extended. By making connection at this point, many of the discontinuities of the right-angle connector are by-passed. Resistor 14 has a value selected so that the impedance of the terminal will match that of the signal carrying cable with contact 12 so positioned.
The grounding of contact 12 to the housing 2 of the outlet, when connector 18 is attached, prevents any current flow or voltage build-up within the terminating circuitry as described which would adversely effect the signal distribution system. To further avoid discontinuities at the outlet, the antenna lead connecting to the outlet through connector 18 is electrically connected to the center conductor 9a prior to the disengaging of contact 12 therefrom; consequently upon withdrawal of connector 18, the drop line is terminated prior to the disconnection of the antenna lead.
The dimensions of housing 2, contact 12 and the other components of the outlet are sized according to well established principles, so that together with resistor 14 they comprise an impedance matching that of the signal supply cable when connector 18 is withdrawn.
While the principles of the invention have been described in connection with the above specific apparatus, it is to be clearlyunderstood that this description is made only by way of example and not as a limitation to the scope of the invention as set forth in the accompanying claims.
What is claimed is:
1. A self-terminating outlet for a signal carrying coaxial cable comprising a coaxial connector having an outer grounded housing and a center conductor, a coaxial outlet jack connected to one end of said connector, a plug-in coaxial connector adapted to mate with said outlet jack, spring contact means biased into interruptable contact with said center conductor, a resistance of preselected ohm value connecting one end of said contact means to electrical ground, means for breaking the contact between said center conductor and said spring contact, and means for making contact between said spring contact and electrical ground, said means for breaking and making contact being actuated by said plug-in connector when it is mated with said outlet jack.
2. The device of claim 1 wherein said means for breaking the contact between said center conductor and said spring contact, and means for making contact between said spring contact and electrical ground comprise an actuating pin slidably attached to said outlet jack in position to push said spring contact away from said center conductor and into contact with said housing.
3. The device of claim 2 wherein the other end of said spring contact makes contact with said center conductor and wherein the other end of said spring contact is angled to the longitudinal axis thereof so as to make wiping contact with said center conductor.
4. The device of claim 3 wherein means for slidably mounting said actuating pin upon said outlet jack includes an actuating ring which slides axially upon said outlet jack, and wherein said plug-in coaxial connector includes a portion adapted to fit over said outlet jack and engage said actuating ring, when said connector is plugged into said jack.
5. The device of claim 4 wherein the ohm value of said resistance has a value selected so that the signal carried cable will be terminated in its characteristic impedance when said spring contact is in contact with said center conductor.
6. The device of claim 5 wherein said coaxial connector comprises a right angle connector having a housing a section of which is removed to provide access for said spring contact to said center conductor, and wherein said spring contact makes contact with the apex of the right angle formed by said center conductor within said right angle connector.
7. The device of claim 6 further including a base plate upon which said coaxial connector is mounted and a block of insulating material attached to said base plate, said spring contact being mounted upon said block of insulating material, said insulating material having a channel therein, and wherein said actuating pin slides within and is guided by the channel in said block of insulating material.
8. The device of claim 7 wherein said base plate has an aperture therein Within which is disposed a portion of said block of insulating material containing said channel, said channel being oriented through said base plate, and
wherein said outlet jack is disposed on one side of said 15 base plate and said spring contact is disposed on the other side of said base plate.
References Cited UNITED STATES PATENTS 2,640,118 5/1953 Werner 200-51.1 X 3,109,997 11/1964 Giger et a1 ZOO-51.1 X 3,459,906 8/1969 OKeefe et a1. 20051.1
10 PAUL L. GENSLER, Primary Examiner US. Cl. X.R.