Signal splitter

[57] ABSTRACT

A connector box for connecting the individual electrodes of a plurality of coaxial cables and especially useful as a splitter box for a television antenna lead-in comprises a two-part casing. Mating upper and lower casing members are cast with corresponding semi-cylindrical out-ward extensions which fit together when the two casing members are placed face to face to provide externally threaded tubular extensions onto which internally threaded collars of coaxial cable connectors can be screwed in turn to clamp such two casing members firmly together. Sleeve connectors are provided within the tubular extensions for effecting electrical connection to the core electrodes of the cables while connection between the sheath electrodes of the cables is usefully effected through the metallic casing of the connector box.

Claims, 4 Drawing Figures

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'66

PATENTED JUL 11 1972

3,676,744

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3,676,744

SIGNAL SPLITTER

BACKGROUND OF THE INVENTION

The present invention relates to electrical connector or junction boxes and more particularly to connector boxes for use with coaxial cables as presently used extensively in television signal transmission systems.

In the coaxial cable systems presently used for the transmission of television signals, especially in the lead-in cables extending from television antennae to television receivers, it is often required to connect certain electronic components to such cables for purpose such as matching and coupling. This is particularly true where it is desired to connect two or more receivers to a single antenna lead. In such a case, it is necessary to interconnect the cables leading to the receivers in such a way that optimum signal strength is provided to each such receiver. Connector boxes adapted to have the coaxial antenna lead-in cable as well as the coaxial or other type of cables for the several receivers interconnected therewithin are already known and are conventionally referred to as “splitters” or “splitter boxes”. Within such splitters, the individual conductors of the several cables are generally interconnected through electronic circuit components of one type or another for purposes such as those already mentioned.

With the growing acceptance of community antenna television systems (CATV) in which householders and others receive television and f.m. program signals through coaxial cables extending from a high quality community antenna, television viewers are coming to demand the high quality reception which they now know can be attained. For this reason, and since more and more households now include more than one television receiver as well as f.m. radios, the use of splitters is expanding at a rapid rate. Such splitters can also be used for connecting a CATV subscriber’s line to a trunk or main distribution line and even for combining signals carried by a number of individual cables.

Splitter boxes heretofore known have, almost without exception, included an electrically conductive metallic box-like casing within which the necessary electronic components are housed. The casings of such previously known splitters are provided with male-threaded connectors to which the several cables are coupled using any of the many well-known types of cable connectors. Lids or cover plates which are retained in position on such boxes by screws or rivets close such known splitter boxes and frequently such a cover plate has been provided with additional screw holes so that the splitter can be mounted on a suitable surface, for example, on a baseboard or on the frame of a window or door. Normally, the malethreaded connectors of such splitters have been mounted on the base, cover or walls of the splitter box so as to project either outwardly from or laterally along the surface on which the splitter box is mounted.

The splitter boxes heretofore known have been relatively large and unsightly, having volumes of at least about 2.5 cubic inches (excluding the male-threaded connectors). Splitters having volumes as high as 9.0 cubic inches are also presently being used in considerable numbers. Such previously known splitters, in addition to being somewhat unsightly when mounted in homes, are also relatively expansive to manufacture and assemble and there is consequently a considerable need for a splitter box which would not only be less expensive to manufacture and assemble but which would be considerably less unsightly in use.

It is accordingly a principal object of the present invention to provide a connector box and more especially a splitter box which is exceedingly simple in its construction and which can be manufactured and assembled at a relatively low cost.

Yet another object of the invention is to provide a connector box for the electrical interconnection of the individual conductors of several cables, at least one of which is of a coaxial type and which connector box is especially suited for use as a splitter box.

A further object of this invention is to provide a connector box of the aforementioned type and which can be constructed to have a very small volume so as to be very much less unsightly and in fact practically inconspicuous in use.

Other objects of the invention will become apparent as the description herein proceeds.

SUMMARY OF THE INVENTION

A connector box in accordance with this invention is characterized by the facts that it has a two-part casing within which any necessary electronic circuit components can be mounted and that the two component parts of the casing of such a splitter box are retained in aligned, opposed and contiguous abutment with each other by means of at least one connector which in turn serves to secure a coaxial cable to the box.

In its broadest scope, the present invention provides a connector box for electrical connection to the individual conductors of at least one coaxial cable and which connector box comprises two separable casing members including mating peripheral walls for defining a box-like enclosure when said casing members are disposed in aligned, opposed and continuous abutment with each other; at least one outward extension of open sectional configuration and integrally formed with said peripheral wall of each said casing member, said outward extension of one said casing member being disposed so as to mate with said outward extension of the other said casing member to form a hollows tubular extension communicating with said box-like enclosure when said casing members are disposed in said aligned, opposed and contiguous abutment with each other; and clamping means on said hollow tubular extension whereby said two casing members may be clamped in said alined, opposed and contiguous abutment with each other by a coaxial cable connector adapted to engage said tubular extension.

It has been found that, by constructing a splitter box in the manner hereinbefore defined, not only can the manufacturing cost of such a box be drastically reduced but also that the box can be formed so as to be much less unsightly in use. In particular, it has been found that splitter boxes with volumes (excluding the tubular extension or extensions to which the cable connector or connectors are attached) as low as 0.5 cubic inches can be provided. As a result of their very small volumes, splitter boxes in accordance with this invention can be mounted in positions in which it was totally impossible to mount previously known splitter boxes. For example, a splitter box in accordance with this invention lends itself to being mounted, for example, beneath the edge of a window ledge in which position it would be almost completely inconspicuous. Additionally, the splitter boxes of this invention are especially suited for mounting within cable distribution conduits and covings.

Although connector boxes in accordance with this invention are especially intended for use as splitter boxes as already explained, it should be understood that such connector boxes may well find utility in other applications where it is desired to interconnect coaxial cables, to connect small electronic circuit components between two such cables, or even to connect other types of cables to a single coaxial cable. Since the principal use of the connector boxes of the invention is as splitter boxes, the ensuing description will more particularly be directed to such an application of the boxes.

Although the invention is not restricted in any way to connector boxes in which the two casing members thereof are formed from a metallic material, the use of an electrically conductive material for such casing members will generally be indicated so that the sheath conductors of several coaxial cables connected to such a box can be mutually interconnected through such a conductive casing.

In order to facilitate the alignment of the two casing members of a connector box in accordance with this invention so that such casing members can be clamped together by a cable

3,676,744 connector as already described, such casing members are usefully provided with alignment means such as alignment pins which are slidably received in corresponding bores, to hold the casing members in mutual alignment while they are being clamped together by the cable connector or connectors. In accordance with another useful feature of the invention, such alignment pins can be formed so that they also function as rivets for holding the casing members in their mutually assembled disposition.

Other features and advantages of the invention will become apparent as the description herein proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described merely by way of illustration with reference to the accompanying drawings in which:

FIG. 1 is an enlarged and exploded perspective view of one embodiment of a connector box in accordance with the invention, certain internal components having been omitted for the sake of clarity;

FIG. 2 is a perspective view of the connector box of FIG. 1 showing the components of that box in their assembled dispositions and showing the box as being connected to a single coaxial cable;

FIG. 3 is an enlarged plan view of the lower casing member of the connector box of FIGS. 1 and 2 when taken as indicated by the arrows 3-3 of FIG. 2 and also showing certain other components of that connector box in section; and

FIG. 4 is a schematic diagram showing the manner in which typical electronic circuit components may be interconnected within the connector box of FIGS. 1,2 and 3 for the use of that box as a two-way splitter in a television antenna lead-in system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The connector box generally indicated at 10 in FIGS. 1 and 2 includes a pair of generally identical casing members in turn generally indicated at 11 and 12. Although the invention embraces the use of casing members formed of any suitable material, particularly useful results can be obtained when the connector box 10 is to be used as a splitter box in a television antenna lead-in system by forming the casing members 11 and 12 as electrically conductive metal castings, for example, of a zinc alloy.

The lower casing member 12 includes a base 14 and upstanding peripheral walls 15, 16, 17 and 18. Similarly, the upper casing member 11 includes a cover 20 and downwardly extending peripheral walls 21,22,23 and 24. A semi-cylindrical upwardly open extension generally indicated at 25 is integrally formed with the wall 16 of the lower casing member 12 and extends normally outwardly therefrom. A similar downwardly open extension generally indicated at 26 is integrally formed with the corresponding wall 22 of the upper casing member 11.

Two spaced apart outward extensions generally indicated at 27 and 28 similar to the extension 25 are likewise integrally formed with the wall 15 of the lower casing member 12 and the wall 21 of the upper casing member 11 is similarly provided with a corresponding pair of extensions 29 and 30. The extensions 26,29 and 30 integrally formed with the upper casing member 11 are disposed so as to mate with respective ones of the extensions 25, 27 and 28 respectively of the lower casing member 12 when the two casing members 11 and 12 are disposed in aligned, opposed and contiguous abutment with each other as will readily be understood by reference to FIG. 2. When so mated, the various semi-cylindrical extensions define tubular extensions generally indicated at 31, 32 and 33 by means of which coaxial cables may be connected to the connector box in a manner yet to be described.

Although the connector box 10 includes three such tubular extensions, it should be understood that the invention is in no way restricted to boxes specifically containing three such extensions.

In the particular connector box 10 shown in the accompanying drawings, the casing members 11 and 12 are clamped together by cable connectors secured to the ends of three coaxial cables between which the box 10 is to be connected.

For this purpose, each of the semi-cylindrical extensions 25, 26, 27, 28, 29 and 30 is formed with an external thread 36 so that, when the two casing members 11 and 12 are disposed in aligned, opposed and contiguous abutment as shown in FIG. 2, the threads on each pair of those extensions mate to provide a continuous external thread on which an internally threaded collar 37 of a conventional coaxial cable connector generally indicated at 38 may be screwed. The threads 36 may be formed on the several semi-cylindrical extensions of the casing members 11 and 12 during the casting of those members or may be individually cut after such casting.

To facilitate the alignment of the upper and lower casing members 11 and 12 respectively in their correct relative positions, each such member is usefully integrally formed with an alignment pin adapted to be slidably received within a corresponding bore in the other one of the casing members. For example, the lower casing member 12 is integrally formed with an upstanding alignment pin 40 which is slidably received in a bore 41 formed in the cover 20 of the upper casing member 11. Similarly, the upper casing member 11 is integrally formed with a downwardly extending alignment pin 42 which is slidably received within a bore 43 formed in the lower casing member 12.

The pins 40 and 42 extend from studs 44 integrally formed with respective ones of the peripheral walls 18 and 23 of the lower and upper casing members 12 and 11 respectively. The engagement of the alignment pins 40 and 42 in the bores 41 and 43 respectively serves positively to maintain the upper and lower casing members 11 and 12 respectively in correct relative disposition while those members are clamped together by screwing cable connectors such as cable connector 38 on the outer ends of the tubular extensions 31,32 and 33 thereof. In order to provide additional alignment between the casing members 11 and 12, the wall 17 of the lower casing member 12 is usefully formed with an inwardly extending semi-cylindrical collar 45 for engagement with the alignment pin 42. A similar collar (not shown) is usefully integrally formed with the wall 24 of the upper casing member 11 for engagement with the alignment pin 40. Such provision of semi-cylindrical collars in distinction to the provision of a cylindrical stud is advantageous in that it provides more space within the connector box 10 for the electronic circuit components which must frequently be interconnected therewithin.

In accordance with another useful feature of this invention, the aforementioned alignment pins 40 and 42 are usefully formed as hollow members with axial bores 46 for receiving mounting screws (not shown) by means of which the connector box 10 may be secured or mounted on a surface, for example, on a baseboard or window frame as will often be desirable when the box 10 is used as a splitter in a television antenna lead-in system. The outer ends of the bores 41 and 43 within which the alignment pins 40 and 42 respectively are received are usefully countersunk as indicated at 47 so that, in accordance with another feature of this invention, one or both of the alignment pins 40 and 42 can be peened outwardly to maintain the casing members 11 and 12 in their assembled disposition.

It will also be understood that to permit the desired electrical connection to the core electrodes or conductors of the several coaxial cables connected to the connector box 10, the interiors of the tubular extensions 31,32 and 33 must communicate with the interior of the casing and that means must be provided for electrical connection to such core electrodes. In order to permit such electrical connection, the casing walls 16 and 22 are provided with mating semi-circular openings 48 which, for a reason yet to be explained, are of a smaller diameter than the internal diameter of the tubular extension 31. In this way, an annular flange 49 is formed at the inner end of the tubular extension 31. Similarly, integrally formed annular

3,676,744 flanges 50 and 51 are provided at the inner ends of the tubular extensions 32 and 33 respectively.

Disposed within each of the tubular extensions 31, 32 and 33, there is provided a sleeve connector generally indicated at 54 similar to a telephone jack and which includes an electrode generally indicated at 55 for making electrical contact with the core conductors of the appropriate ones of the coaxial cables automatically when such cables are connected to the ends of respective ones of the tubular extensions 31, 32 and 33 by means of cable connectors such as the connector 38. For the sake of clarity, the sleeve connector 54 of only the tubular extension 33 is shown in FIG. 1 while the identical sleeve connectors 54 for the tubular extensions 31 and 32 are shown in FIG. 3, the connector for extension 33 having been omitted from the last mentioned figure. Since all the sleeve connectors 54 are identical to each other, it will be sufficient herein to describe the structure of only one such connector.

Each of the sleeve connectors 54 includes an electrically insulating, generally cylindrical electrode holder 56 into which the inner end 57 of the electrode 55 is moulded or otherwise inserted and usefully keyed against rotation. The holder 56, which may conveniently be formed of a suitable plastics material, has an external diameter substantially equal to the internal diameter of the respective one of the tubular extensions 31, 32 and 33 and consequently, when disposed within such extension, its inner end engages a respective one of the aforementioned annular flanges 49, 50 and 51. Such sleeve connector 54 is consequently restrained against inward movement out of the respective one of the tubular extensions. At its outer end, the holder 56 is integrally formed with a cylindrical skirt 58 of somewhat reduced diameter so as to define an outwardly facing annular shoulder 59. An electrically insulating cover generally indicated at 60 and including a cylindrical wall 61 and an end wall 62 defining a chamber 63 fits over the skirt 58 and seats on the shoulder 59. An axial opening 64 is provided through the end wall 62 for the passage therethrough of the core conductor 65 of a coaxial cable.

Usefully the outward extensions 25,26,27,28,29 and 30 of the casing members 11 and 12 are integrally formed at their outer ends with inwardly projecting flanges 66 which abut the outer ends of the respective covers 60 so as to retain the sleeve connectors 54 within the tubular extensions 31, 32 and 33 although the provision of such flanges 66 is not absolutely essential. In the particular connector box 10 shown in the accompanying drawings, the tubular extensions 32 and 33 are shown as being provided with such flanges 66 while the tubular extension 31 is shown as being formed without such a flange. In general, such flanges 66 will be provided on those tubular extensions for which disconnection and reconnection of the cable connectors is likely to be required from time to time.

Within the chamber 63 of the connector 54, the electrode 55 includes two spring metal arms 67 and 68 which are formed to provide a restriction 69 for pinching engagement with the core conductor 65 as will best be understood by reference to FIG. 3 of the accompanying drawings. The inner end 57 of the electrode 55 usefully extends inwardly beyond the inner end of the holder 56 as at 70 to facilitate electrical connection thereto within the connector box 10.

Although the coaxial cable connectors 38 used for securing the several coaxial cables to the connector box 10 and functioning to clamp the upper and lower casing members 11 and 12 respectively of that box together do not in themselves constitute an essential component of a connector box in accordance with the invention, the structure of such a cable connector 38 will briefly be explained with particular reference to FIG. 3. From that figure, it will be seen that the connector 38 serves to connect the coaxial cable generally indicated at 72 to the connector box 10. The cable 72 includes the aforementioned core conductor 65 and a braided wire sheath electrode 73. The electrodes 65 and 73 are separated within the cable 72 by a cylindrical inner insulation 74 while the sheath electrode 73 is externally covered by an outer insulating layer 75.

The connector 38 includes an annular stop plate 78 against which the ends of the outer insulation 75 and of the sheath electrode 73 are seated. A sleeve 81 is integrally formed with the stop plate 78 frictionally to retain the stop plate 78 in position on an inward axial extension 84 of a metallic sleeve 79 formed with an annular radial protrusion or barb 80 and which is inserted between the sheath electrode 73 and the inner insulation 74 for electrical contact with that sheath electrode 73. A ferrule 82 is crimped about the cable 72 on the box side of the aforementioned barb 80 to ensure positive electrical contact between the sheath electrode 73 and the sleeve 79. A retaining ring 83 is integrally formed with the inward axial extension 84 of the sleeve 79 for engagement within a centrally apertured end plate 85 integrally formed with the collar 37 to hold the retaining ring 83 in firm mechanical and electrical contact with the outer end of the tubular extension 31. It will further be understood that the core conductor 65 of the cable 72 will be exposed before the connector 38 is secured thereto, as is conventional, and that, as the collar 37 of the connector 38 is screwed onto the mating threads 36 of any of the tubular extensions 31, 32 and 33 of the upper and lower casing members 11 and 12 respectively, the core conductor 65 will be engaged in the restriction 69 of the respective electrode 55 while the sheath electrode 73 of the cable will be brought into electrical contact with the metallic casing members 11 and 12 through the relevent conductive parts of the connector 38. In this way, the sheath electrodes of all the coaxial cables so coupled to the connector box 10 will be electrically interconnected.

Any desired interconnection of the core conductors 65 of such cables may be obtained by appropriately interconnecting the inner ends 70 of the electrodes 55 within the connector box 10. Merely by way of illustration, one suitable system for the interconnection of such electrodes will now be briefly described with reference to FIG. 4 of the accompanying drawing? in which the electrical connection of the various sheath conductors 73 to the casing members 11 and 12 is shown somewhat schematically by lines 37' representing respective ones of the collars 37.

The circuit shown in FIG. 4 is particularly intended for use when the connector box 10 is to be used as already indicated as a splitter in a television antenna lead-in system, in which case the antenna lead-in or CATV cable will be connected in the manner already described to the tubular extension 31 while the two output cables will be connected to the tubular extensions 32 and 33. Within the connector box 10, the extension 70 from the core conductor of the lead-in cable is coupled through a transformer generally indicated at 90 to the electrode extensions 70 from the two output cable core conductors, a resistor 91 of appropriate value being connected between the electrode extensions 70 of the output cables. The transformer primary winding is “grounded” to the metallic casing of the connector box 10 while a capacitor 92 is connected between appropriate points on the transformer winding? and the metallic casing of the box 10 to facilitate impedance matching. To facilitate such grounding connection, a grounding solder tag or terminal 93 is shown as being provided.

The tag 93 which is also shown in FIG. 1 is, in accordance with another useful feature of this invention, adapted to be clamped between the upper and lower casing members 11 and 12 respectively when the latter are clamped together in their correct juxtaposition by the collars 37 of the several cable connectors 38. For this purpose, the tag 93 is usefully formed with an annular lug 94 which can be disposed around either one of the alignment pins 40 and 42 so as to be compressed between a respective one of the studs 44 and a respective one of the collars 45 to ensure electrical contact of that tag with the casing members. The provision of such a tag is particularly advantageous when the casing members 11 and 12 are formed from a metal which is not readily solderable, as a result, for example, of the composition of that metal or simply because the casing members constitute too great a heat sink.

3,676,744

As hereinbefore stated, the invention is in no way restricted to a connector box provided with three tubular extensions as shown in the accompanying drawings. For example, in the case of the use of a connector box in accordance with this invention as a splitter box, it will be understood that it may be required to couple more than two output lines to a single leadin cable. In such a case, the connector box can then be provided with that many more tubular extensions. The use of fewer tubular extensions is also possible for applications where it is desired to connect various components into a single coaxial cable or to connect a single coaxial cable to one or more cables of a different type. Numerous variations in the detailed construction of the sleeve connectors 54 are also possible without departing from the scope of the invention.