Abstract:
A coaxial connector is disclosed for terminating a coaxial transmission line. The connector includes a tubular spring element, comprising a cylindrical body having a plurality of reversely formed leaf spring fingers annularly spaced, and projecting forwardly therefrom. The spring fingers are intended for positionment within a tubular plug shell, and are engaged and compressed upon insertion of a jack body therebetween for retaining and electrically contacting the jack body.

Description:
BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates to coaxial connector plugs, generally, and specifically to SMB-style coaxial plugs and jacks. 
     2. The Prior Art 
     Coaxial connectors available presently in the industry, comprise a variety of different styles. One commercially popular style is the so called SMB plug and jack, which is defined by military specifications and functions to terminate coaxial transmission lines. 
     Presently available SMB style coaxial plugs generally comprises a female member having a slotted tubular structure forming jaws, a split ring having a diameter which receives the tubular member therein for providing spring resiliency, and an outer protective hood for protecting the jaw member. Such a structure is illustrated in U.S. Pat. No. 3,745,514. Pursuant thereto, a male member is inserted into the slotted tubular part, causing the jaws to resiliently expand, with the degree of expansion controlled by the split ring encompassing the jaws. 
     While the above identified connector is generally accepted by the industry several shortcomings prevent this configuration from totally satisfying the needs of the industry. First, the presently available connector is composed entirely of screw machine formed components, which adds considerably to the cost of the unit and thereby limits its acceptance in the market. Specifically, the slotted tubular part is screw machine from brass and the outer split ring, which wraps around the slotted part, is formed of copper to provide resiliency. A separate hood is also taught by the prior art for surrounding the aforesaid components for the purpose of protection. This type of construction and assembly is relatively expensive, comprises a relatively large number of components, and results in a somewhat larger dimensioned plug than the industry would prefer. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention relates to a SMB-style coaxial connector, comprising a unitary tubular shell body having a tubular spring element seated therein which is configured as follows. The spring element includes a large cylindrical forward end, having a plurality of forwardly projecting leaf spring fingers annularly spaced about the forward periphery of the cylindrical portion. Each of the spring fingers is provided with a reversely bent U-shaped profile, which is compressably engaged by the contact shell of a mating jack upon coupling. The compression of the spring fingers accomplishes the two-fold objectives of establishing electrical contact between the plug and jack, as well as effectuating positive retention of the jack shell inside of the plug shell. The conductive component parts of the present invention are comprised entirely of either stamped and formed or drawn bodies, which substantially reduces the cost of manufacturing. Moreover, the present configuration includes fewer component parts, which are readily assembled, requiring no soldered connections, and results in a smaller plug profile. Thus, the prescribed military specifications are satisfied, but a lower cost is incurred in manufacturing the presently configured coaxial connector over the connectors of the prior art. The tubular shell body is further provided with means for protecting the spring fingers from misengagement and lateral manipulation of the jack. 
     Accordingly it is an object of the present invention to provide a coaxial connector for terminating coaxial transmission cable which comprises relatively few component parts. 
     A further object of the present invention is to provide a coaxial connector which is fully crimpable to coaxial cable. 
     Yet a further object of the present invention is to provide a coaxial connector having a relatively small diameter profile. 
     Still further, it is an object of the present invention to provide a coaxial connector which comprises stamped and formed contacts, and drawn body members. 
     A still further object of the present invention is to provide a coaxial connector which provides for convenient assembly, and which comprises improved spring retention means and means for protecting said spring retention means. 
     Still a further object of the present invention is to provide a coaxial connector which is economically and readily produced, and readily assembled. 
     These and other objects, which will become apparent to one skilled in the art are achieved by a preferred embodiment which is described in detail below and which is illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
     FIG. 1 is an exploded view of the subject coaxial connector plug configured pursuant to the present invention. 
     FIG. 2 is a partially assembled view of the subject coaxial connector plug, with the center contact affixed to the center conductor of the cable, and the dielectric body inserted into the spring element. 
     FIG. 3 is a longitudinal section view through the completed subject coaxial connector plug. 
     FIG. 4 is a longitudinal section view through the forward end of the subject coaxial connector plug illustrated in FIG. 3, together with the forward end of the mating jack half. 
     FIG. 5 is a partial longitudinal section through forward portions of the mated plug and jack, illustrating operation of the shell body in protecting the spring element fingers. 
     FIG. 6 is a partial section through forward portions of a jack and a plug, not configured pursuant the present invention for the purpose of contrast and explanation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIG. 1 the subject invention comprises a coaxial connector plug including the following components: a tubular spring element 2 having an axial bore 3 extending therethrough; a dielectric body 4 having an axial bore 5 extending therethrough; a shell body 6 likewise having an axial bore 7 extending therethrough; a center contact having an axial bore 9 extending therethrough; and a crimping ferrule 10. The subject plug is intended for termination of a coaxial transmission cable comprising a center conductor 12, surrounded by a dielectric layer 14, which in turn is surrounded by an outer conductive shield 16 and an outer insulative sheath 17. The tubular spring element 2 is structured having a rearward cylindrical portion 18 of generally smaller diameter dimension, and a larger dimensioned forward cylindrical portion 20 integrally joined to portion 18 by a shoulder 19. A plurality of integral spring fingers 22 are annularly spaced about the forward peripheral profile of the cylindrical portion 20, and project forwardly therefrom. Each spring finger 22 constitutes an inner leaf 24 integrally joined to the cylindrical portion 20, and a reversely formed outer leaf 26. The inner leaf 24 is further provided with a transversely extending detent ridge 28 formed as illustrated. The above configured spring member 2 is formed in a progressive dye in a manner common in the industry. 
     The dielectric body 4 has a generally elongate profile and unitarily includes a forward cylindrical sleeve 30 and rearwardly disposed, coaxial outer cylindrical sleeve 32 and inner cylindrical sleeve 34. The coaxial sleeves, 32, 34 are radially spaced apart by a gap 33 as best seen in FIG. 4. The inner cylindrical sleeve 34 also provides an annularly extending detent 35 which projects into the axial bore 5. Also, from FIG. 1, the dielectric body 4 includes an annular flange 36 which is located at a rearward end of the body. 
     The outer shell 6 is of a unitary construction, and constitutes a forward relatively large diametered hood 38, an intermediate cylindrical portion 40, and a rearward smaller diametered portion 42. The shell 6 provides an internal shoulder 44 as best viewed from FIG. 4. 
     Returning to FIG. 1, the center receptacle contact 8 is configured having a rearward crimping barrel 46, an intermediate annular retention recess 48, and a female receptacle portion 50 at the forward end thereof. Likewise, the crimping ferrule 10 is provided with a rearward crimp barrel 52 at the rearward end thereof. An outwardly directed annular flange 54 is provided at the forward end of the crimping ferrule 10. 
     Proceeding to FIG. 4, the above described coaxial connector plug intermates with a coaxial jack 56, comprising a center pin 58, an outer conductive shell 60, which is electrically isolated from the center pin 58 by a dielectric body 62. The outer conductive shell 60 is provided with an annularly extending retention recess 64 spaced a prescribed distance from the forward end of the jack. 
     Proceeding to the assembly of the subject coaxial connector plug as illustrated in FIGS. 1 and 2, the coaxial cable is extended through the crimping ferrule 10, and dressed for termination. So prepared, the center conductor 12 projects forwardmost, followed by the dielectric layer 14, and an exposed forward length of the outer conductive shield 16. Thereafter, the center contact 8 is affixed to the center conductor 12, which is inserted into the crimping barrel 46 of contact 8, and subsequently crimped in a conventional manner. 
     Proceeding, the dielectric body 4 is inserted into the axial bore 3 of the tubular spring element 2, and there positioned serves to electrically isolate the spring element from center contact 8 when inserted into bore 5. The spring element 2 is then press inserted into the axial bore 7 of the shell body 6 from a forward end thereof. Thus assembled, as shown best in FIG. 4, the internal shoulder 19 of the spring element 2 abuts against the internal shoulder 44 of the shell body 6, and the outer leaf 26 of each spring finger 22 contacts the forward hood 38 of the shell body. It will be appreciated from FIG. 4 that the forward end 66 of the hood portion 38 is thereafter rolled over to capture spring element 2 within the shell body 6, as well as to provide protective and lead-in functions as explained below. 
     Collectively viewing FIGS. 2 and 4, the center contact 8 is inserted into the dielectric body bore 5, and is retained therein as the annular detent 35 snaps over the annular retention groove 48 of the contact. It will be appreciated that the insertion of the contact 8 into the dielectric body 4, causes an outward deflection of the inner cylindrical portion 34, which is facilitated by the spacing 33 between the inner cylinder 34 and the outer cylinder 32. Pursuant to this configuration, the inner cylinder 34 serves as a resilient spring and provides the requisite resilient retention forces for retaining the center contact within the dielectric body. The air gap 33 simultaneously provides a means for achieving impedance matching in the plug. 
     Referring now to FIG. 3, the rearward portion 42 of the shell body 6 is inserted beneath the outer conductive shield 16 of the coaxial cable, and the crimping ferrule 10 is transported forwardly to entrap the exposed portion of the conductive shield against portion 42 of the shell body. The crimping ferrule 52 is radially crimped in a conventional manner. The annular flange 54 of the crimp ferrule 10 has been rolled over as indicated in FIG. 3 during manufacture to eliminate the exposure of sharp edges. 
     Proceeding to FIG. 4, it should be noted that in the normal condition, the outer leaf 26 of each spring finger 22 contacts the hood 38 of the shell body, but is not compressed thereby. As the mating jack 56 is inserted between the spring fingers 24, the outer conductive body 60 of the jack influences the spring fingers radially outward and against hood portion 38. Further insertion of the jack into the plug, terminates when the transverse detent ridges 28 of the spring fingers snap into the annular retention recess 64 of the plug body 60. Simultaneously, the center pin 58 penetrates and engages with the female receptacle 50 to electrically interconnect with the center conductor of the coaxial cable. 
     In the mated condition, the spring leaves 24 and 26 are under a compressive tension and serve to ensure good mechanical and electrical contact between the spring element 2 and the jack body 60. This constitutes an electrical path between the outer conductive shield 16 of the coaxial cable and the outer conductive body 60 of the jack. 
     The leaf springs 24, 26, simultaneously acting together through detent ridge 28, provide the requisite inwardly directed forces to ensure good electrical contact between the jack shell 60 and the detents 28 disposed in recess 64. Also simultaneously, the leaf springs 24, 26, acting together provide the necessary forces for achieving mechanical retention of the jack body within the plug, not readily achievable by conventionally available single spring contacts. It will be noted that leaf spring 24 functions as a cantilever spring, and that spring 26 operates cumulatively with spring 24 to provide additional radial spring action. Further the profile of spring 26 is such that contact with the hood portion 38 is at a point counter to the detent ridge 28 of spring 26. This serves to concentrate the spring force through detent ridge 28 for improved results. 
     Referring to FIG. 5, the subject plug is shown mated to the jack 56. The detent ridge 28 of the spring fingers 22, after riding over the forward end of the outer jack body 60, resiliently locks into the jack retention recess 64. Fully inserted, the forward end of the jack body 60 is generally situated adjacent the inner end of the forward plug hood 38. The purpose of the rolled portions 66 of the hood 38 is illustrated by FIGS. 5 and 6. First, the rolled portions provide a lead in for centering the jack body 60 between the inner spring finger leaves 24. Without such a configuration, as shown in FIG. 6, the jack can axially misalign with the plug during mating, and stub against ends of the spring fingers 22, resulting in deformation of the fingers. Secondly, as will be apparent from FIG. 5, the rolled forward edge 66 of the plug hood 38 protect the spring fingers 22 from damage due to lateral manipulations of the plug or jack. The edge 66 limit the degree to which the plug can be laterally manipulated during or after mating with the jack, by stopping against the outer jack body 60. Otherwise, careless lateral manipulation of the plug during withdrawal from the jack could debilitatively damage the spring fingers 22. Thus, the presence of rolled edge 66 serves to protect the spring fingers 22 from damaging engagement with the jack. 
     It is to be understood that the above described preferred embodiment of the present invention is merely illustrative. Other embodiments, which will become apparent to one skilled in the art, and which utilize the teachings herein set forth, are intended to be within the scope and spirit of the subject invention.