Abstract:
An electric connector ensuring effective grounding contact includes coaxially arranged inner sleeve and outer sleeve and a conductive grounding element. The inner sleeve is adapted to receive a central conductor and an insulating spacer of a cable therein, and can be axially rearward moved from a first position to a second position, and the outer sleeve is adapted to receive a braided conductive grounding sheath and an insulating sheath of the cable therein. The conductive grounding element is externally immovably fitted around the inner sleeve. When a stripped free end of the cable is inserted into the connector and the cable is rearward pulled, the inner sleeve is simultaneously rearward moved from the first position to the second position, forcing the inner sleeve, the conductive grounding element, and a connecting ring coaxially mounted around the inner sleeve to electrically contact with one another.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a connector, and more particularly to an electrical connector having structure ensuring effective grounding contact. 
   BACKGROUND OF THE INVENTION 
   In signal transmission applications, the selection of a coaxial cable for carrying the signal is usually determined according to the distance between two points to be connected, the signal frequency, the maximum bend radius required, and the connector space available in a particular transmitting and/or receiving device. The longer the coaxial cable is and the higher the signal frequency is, the larger the outside diameter of the coaxial cable needs to be to prevent excessive signal loss. Conventionally, coaxial cables that are applied in cable TV transmission, broadband data transmission, and microwave signal transmission usually have an outer diameter ranged from 0.25 to 1 inch when the transmission distance is between 50 and 1000 feet. 
   A coaxial connector is well-known in the technological field of coaxial cable transmission. Typically, a coaxial connector is connected to a mating interface connector, so that a coaxial cable connected to the coaxial connector can be electrically connected to various kinds of electronic devices. 
   The conventional connector for a coaxial cable has some disadvantages. For instance, to ensure good electric signal transmission, it is a must a braided conductive grounding sheath of the coaxial cable is in good contact with a main body of the connector. However, with the conventional coaxial connector technique, poor grounding contact might occur between different components, such as an inner sleeve and a collar, of the connector to result in interrupted signal transmission.  FIG. 1A  is a sectional view of an F-series connector  10 , being illustrated as a representative example of the conventional connectors. The F-type connector  10  includes an outer sleeve  11 , a collar  12  coaxially fitted in the outer sleeve  11 , an inner sleeve  13  axially movably fitted in the collar  12 , and a nut-shaped connecting ring  14  rotatably mounted around the collar  12 . 
   As can be seen in  FIG. 1B , a free end of a cable  15  can be inserted into the connector  10 , such that a central conductor  16  and an insulating spacer  17  of the cable  15  are received in the inner sleeve  13  while a braided conductive grounding sheath  18  and an insulating sheath  19  of the cable  15  are located in an annular space between the outer sleeve  11  and the inner sleeve  13 , allowing the cable  15  to be connected to the connector  10 . When the free end of the cable  15  has been fully inserted into the connector  10 , the cable  15  can be pulled with a sufficient force to compel the inner sleeve  13  to move from a first position closer to a front end of the connecting ring  14  to a second position closer to a rear end of the connecting ring  14 , so that the inner sleeve  13  and the collar  12  are in effective grounding contact, and the outer sleeve  11  is tightly connected at a radially inward annular rib  111  thereof to the insulating sheath  19  of the cable  15 . 
   However, in the event the pull applied to the cable  15  is insufficient, a space S will exist between the inner sleeve  13  and the collar  12 , resulting in poor contact between the inner sleeve  13  and the collar  12 . The poor contact between the inner sleeve  13  and the collar  12  will further degrade the electrical characteristic of the connector  10 . It is obviously necessary to overcome such poor contact between the inner sleeve  13  and the collar  12  of the connector  10 . 
   Therefore, it is tried by the inventor to develop a connector, which not only ensures effective connection of the connector main body to a coaxial cable, but also ensure good grounding contact between components in the connector main body over a long period of time, so as to maintain the cable and the connector in good electrical characteristic. 
   SUMMARY OF THE INVENTION 
   A primary object of the present invention is to provide an electrical connector, which includes a conductive grounding element to establish stable grounding contact between internal components of the connector, so as to ensure good signal transmission quality and maintain the connector in good electrical characteristic. 
   To achieve the above and other objects, the electrical connector ensuring effective grounding contact according to the present invention includes coaxially arranged inner sleeve and outer sleeve and a conductive grounding element. The inner sleeve is adapted to receive a central conductor and an insulating spacer of a cable therein, and can be axially rearward moved from a first position to a second position, and the outer sleeve is adapted to receive a braided conductive grounding sheath and an insulating sheath of the cable. The conductive grounding element is externally immovably fitted around the inner sleeve. When a stripped free end of the cable is inserted into the connector and the cable is rearward pulled, the inner sleeve is simultaneously rearward moved from the first position to the second position, forcing the inner sleeve, the conductive grounding element, and a connecting ring coaxially mounted around the inner sleeve to electrically contact with one another. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein 
       FIG. 1A  is a sectional view of a conventional connector; 
       FIG. 1B  is a sectional view showing the connection of a coaxial cable to the conventional connector of  FIG. 1A ; 
       FIG. 2  is an assembled cutaway perspective view of an electrical connector ensuring effective grounding contact according to a preferred embodiment of the present invention; 
       FIG. 3  is an assembled sectional view of the electrical connector of  FIG. 2 ; 
       FIG. 4  is a sectional view of an outer sleeve included in the electrical connector of the present invention; 
       FIG. 5  is a sectional view of a connecting ring included in the electrical connector of the present invention; 
       FIG. 6  is a sectional view of an inner sleeve included in the electrical connector of the present invention; 
       FIG. 7  is a perspective view of a conductive grounding element included in the electrical connector of the present invention; and 
       FIGS. 8A to 8C  illustrate the manner of installing the connector of the present invention on a coaxial cable. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following description of the present invention, for the purpose of easy to understand, elements that are the same in the accompanying drawings are denoted by the same reference numerals. Please refer to  FIGS. 2 and 3  that are assembled cutaway perspective view and assembled sectional view, respectively, of an electrical connector ensuring effective grounding contact according to a preferred embodiment of the present invention. As shown, the electrical connector is generally denoted by reference numeral  20 , and includes an outer sleeve  22 , a connecting ring  30 , an inner sleeve  40 , and a conductive grounding element  50 . 
   As can be seen in  FIG. 4 , which is a sectional view of the outer sleeve  22 , the outer sleeve  22  includes a main body  23  internally defining a bore  24 . The bore  24  has an inner diametrical size large enough for receiving a partial length of the connecting ring  30  therein. A circle of rearward tapered conical inner wall portion  25  is formed in and around the bore  24  near a front end thereof. A radially inward annular flange  26  is formed in the main body  23  of the outer sleeve  22  adjacent to a rear end of the bore  24 , and the annular flange  26  defines an opening  27  therein. The opening  27  has a diametrical size large enough for receiving a free end of a coaxial cable  60  therein, as can be seen in  FIG. 8A . 
     FIG. 5  is a sectional view of the connecting ring  30 . The connecting ring  30  is located at a front end of the connector  20 , and can be used in differently configured connecting interfaces, such as F, BNC, RCA, and IEC connectors. In the illustrated embodiment, the connecting ring  30  is used in an F connector. The connecting ring  30  includes a front screwing body  31  having a hexagonal outer face, and a rear hollow cylindrical portion  32 . The hexagonal front screwing body  31  is internally provided with screw threads  33  and a circle of radially inward flange  34 . The screw threads  33  can mesh with a mating connecting interface on an electronic device, so that the electronic device is mechanically and electrically connected to the coaxial cable  60  via the connector  20 . The inward flange  34  defines a bore  35  for the conductive grounding element  50  to pass therethrough. 
   The rear hollow cylindrical portion  32  internally defines a bore  36 , which has a diametrical size large enough for receiving a braided conductive grounding sheath  63  and an insulating sheath  64  of the coaxial cable  60  between the rear hollow cylindrical portion  32  and the inner sleeve  40 . An annular groove  37  is formed around an outer wall face of the hollow cylindrical portion  32 . When the hollow cylindrical portion  32  of the connecting ring  30  is inserted into the bore  24  of the outer sleeve  22 , the conical inner wall portion  25  in the outer sleeve  22  is received in and engaged with the annular groove  37 , such that the connecting ring  30  is freely rotatably in the outer sleeve  22 . 
   As shown in  FIG. 6 , the inner sleeve  40  defines a bore  41 , which has a diametrical size large enough for receiving a central conductor  61  and an insulating spacer  62  of the coaxial cable  60  therein. An annular tooth  42  is formed around an inner wall surface of the bore  41  at a predetermined position with a sharp edge of the tooth  42  directed toward a front end of the inner sleeve  40  to prevent the coaxial cable  60  from moving out of the connector  20 . The inner sleeve  40  includes a radially outward flange  43  formed around a front end thereof, an interfacing portion  44  behind the outward flange  43 , and a slope-contained tubular portion  45  behind the interfacing portion  44 . The interfacing portion  44  is sized for fitting in the conductive grounding element  50 , and is coaxially located in the hexagonal front screwing body  31  of the connecting ring  32 . The slope-contained tubular portion  45  is coaxially located in the bore  36  defined in the rear hollow cylindrical portion  32  of the connecting ring  30 , such that the hollow cylindrical portion  32  is concentrically disposed around the slope-contained tubular portion  45  with an annular hollow space  46  formed between the cylindrical portion  32  and the slope-contained tubular portion  45 , as shown in  FIG. 3 . The slope-contained tubular portion  45  includes a circle of rearward declined first slope  47  and a circle of rearward declined second slope  48  respectively externally formed at a front and a rear end thereof. 
   Please refer to  FIG. 7 . The conductive grounding element  50  includes a tubular main body  51  for externally immovably fitting around the interfacing portion  44  of the inner sleeve  40 . On the tubular main body  51 , there is integrally formed a plurality of front elastic leaves  52  and a plurality of rear elastic leaves  53 . In the illustrated embodiment, there are four front elastic leaves  52  and four rear elastic leaves  53  respectively circumferentially and equally spaced along a wall of the tubular main body  51 . 
   The front and the rear elastic leaves  52 ,  53  are formed on the conductive grounding element  50  by radially outward punching the wall of the tubular main body  51 . As shown in  FIG. 3 , before the assembled connector  20  is connected to the coaxial cable  60 , the inward flange  34  of the connecting ring  30  is located between the rear elastic leaves  53  of the conductive grounding element  50  and the first slope  47  of the inner sleeve  40 , so that the inner sleeve  40  is not freely axially movable. However, when a rearward pull is applied to the inner sleeve  40 , the rear elastic leaves  53 , due to the elasticity thereof, can be radially inward compressed by the inward flange  34  to thereby pass through the bore  35  defined in the inward flange  34 . Thereafter, the front elastic leaves  52  are also radially inward compressed by the inward flange  34  to pass through the bore  35 . Finally, the outward flange  43  of the inner sleeve  40  is pressed against the inward flange  34  of the connecting ring  30  under the pull and the inner sleeve  40  can no longer be axially moved rearward. At this point, the front elastic leaves  52  will spring radially outward to a predetermined position for electrically contacting with the inward flange  34 . 
     FIGS. 8A to 8C  show the manner of installing the connector  20  on the cable  60 . The cable  60  includes, from outer to inner side, the insulating sheath  64 , the braided conductive grounding sheath  63 , the insulating spacer  62 , and the central conductor  61 . Please refer to  FIG. 8A . Before installing the connector  20 , first strip a length of the insulating sheath  64  from a free end of the cable  60 , and turn part of the exposed braided conductive grounding sheath  63  backward to expose a length of the insulating spacer  62  and the central conductor  61 . Meanwhile, the outward flange  43  on the inner sleeve  40  of the connector  20  before installing is located at a first position closer to a front end of the connecting ring  30 . Then, as shown in  FIG. 8B , the stripped free end of the coaxial cable  60  as prepared in  FIG. 8A  is inserted into the inner sleeve  40  to contact a front end of the insulating spacer  62  with a flat inner end surface  49  of the front end of the inner sleeve  40 . While inserting the cable  60  into the inner sleeve  40 , the slope-contained tubular portion  45  of the inner sleeve  40  is forced into between the braided conductive grounding sheath  63  and the insulating spacer  62  of the cable  60 . With the slope-contained tubular portion  45  of the inner sleeve  40  extending between the braided conductive grounding sheath  63  and the insulating spacer  62 , the circular tooth  42  is forced against an outer circumferential surface of the insulating spacer  62  to tightly engage with the insulating spacer  62 , bringing the inner sleeve  40  to firmly mechanically connect to the cable  60 , so that the free end of the cable  60  is held in the connector  20 . 
   Then, a force in the direction as indicated by the arrows X in  FIG. 8B  is applied to the coaxial cable  60 , so that the cable  60  is moved into a final connected position in the connector  20 , as shown in  FIG. 8C . When pulling the cable  60  as shown in  FIG. 8B , the outward flange  43  of the inner sleeve  40  is simultaneously moved backward from the first position closer to the front open end of the connecting ring  30  to a second position, at which the outward flange  43  of the inner sleeve  40  is abutted on the inward flange  34  of the connecting ring  30 . When the inner sleeve  40  is axially moved rearward, the front and rear elastic leaves  52 ,  53  on the conductive grounding element  50  are radially inward compressed by the inward flange  34  to thereby rearward pass through and locate behind the inward flange  34 . At this point, the front elastic leaves  52  are electrically contacted at free ends with the inward flange  34  of the connecting ring  30  to establish good grounding contact between them to ensure good signal transmission quality and good electrical characteristic of the connector  20 . 
   The present invention has been described with a preferred embodiment thereof and it is understood that many changes and modifications in the described embodiment can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.