Patent Publication Number: US-6217381-B1

Title: Connector for a coaxial cable and its connecting method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a connector for a coaxial cable and its connecting method. 
     2. Description of the Related Art 
     A method of connecting a connector to a coaxial cable such as shown in FIG. 17 has been conventionally proposed. This method consists of folding the braid  81   b  of a coaxial cable  81  back on the sheath  81   c , inserting into a connection hole  82   a  of a terminal  82  and bending the conductor  81   a  of the coaxial cable  81 , and soldering and electrically connecting the conductor  81   a  to the terminal  82 , so as to produce a terminal-attached cable  80 . 
     The terminal-attached cable  80  is placed on a pair of holder bodies  83   a ,  83   a  of an insulating terminal holder  83 , and the pair of holder bodies  83   a ,  83   a , as shown in FIG. 18, are closed to fix the terminal-attached cable  80  therein and provide a holder-attached cable  84 . As shown in FIG. 19, the holder-attached cable  84  is inserted into a conductive sleeve  85  from the rear, and the latter is then crimped on and electrically connected to the folded-back braid  81   b . After completion of the crimping, that part of the braid  81   b  exposed from the sleeve  85  is cut with a cutting means and removed to provide a connector-attached coaxial cable  86 . 
     With the method as mentioned above, however, the process from soldering the conductor  81   a  to the terminal  82  to crimping the sleeve  85  onto the braid  81   b , as apparent from FIGS. 17 to  19 , involves setting the terminal-attached cable  80  in the terminal holder  83  and setting the holder-attached cable  84  in the sleeve  85 , during each of which load tends to be imposed on the conductor  81   a , possibly resulting in impairment of quality. Besides, the method, due to its complexity, is not adapted for automating, resulting in a poor production efficiency. 
     Further, another method of connecting a coaxial cable connector such as shown in FIG. 20 has been proposed in U.S. Pat. No. 5,110,308. This method includes inserting the coaxial cable  81  into the adapter portion  92  of a T-shaped housing  91  and inserting the conductor  81   a  into a connection hole  93   a  of the terminal portion  93  inside the housing  91  for electrically connecting the conductor  81   a  to the terminal portion  93 . 
     The adapter portion  92  is pushed in between the insulator  81   d  and the braid  81   b , followed by, as shown in FIG. 21, bending the sleeve portion  94  of the housing  91  toward the coaxial cable. The braid crimp piece  94   a  of the sleeve portion  94  is crimped on the braid  81   b  to electrically connect the sleeve portion  94  to the braid  81   b . A connector-attached cable  90  is thus obtained. 
     With the method as mentioned above, however, because the terminal portion  93 , adapter portion  92  and sleeve portion  94 , as apparent from FIGS. 20 and 21, are provided in one piece by molding, an insulating member  95  needs to be inserted around the terminal portion  93  to prevent a short circuit between the terminal portion  93  connected to the conductor  81   a  and the sleeve  94  connected to the braid  81   b , which is troublesome. Further, because the method involves bending the sleeve portion  94 , the coaxial cable  81  may erroneously get damaged or the housing  91  may be deformed during the bending operation, resulting in lowered reliability of the product. 
     SUMMARY OF THE INVENTION 
     This invention has been accomplished to overcome the above drawbacks and an object of this invention is to provide a connector for a coaxial cable which attains a reduced load on the conductor of a coaxial cable after its connection to the related terminal, which is produced by a simplified manufacturing process, and which keeps the product from being lowered in reliability. 
     In order to attain the object, according to an aspect of this invention, there is provided a connector for a coaxial cable, the coaxial cable including a conductor, an insulator around the conductor, a braid around the insulator, and a sheath around the braid, which comprises: a terminal provided with a connection hole into which the conductor of the coaxial cable is inserted for electrical connection with the terminal; an insulating terminal holder including a holder body for receipt therein of the terminal and a pair of opposed first and second lids provided at one end of the holder body at a side wherefrom the terminal is received into the holder body, the first lid, when closed, locking the terminal in the holder; and a conductive shield cover including a cover body detachably mounted on the terminal holder inclusive of the first lid in the closed position and a holding means provided at one end of the cover body toward the coaxial cable, the connection hole of the terminal and the holding means being longitudinally aligned with each other when the cover body is mounted on the terminal holder, wherein when the coaxial cable is advanced toward the terminal, after the terminal is locked in the holder body by the first lid and the shield cover is mounted on the terminal holder, the conductor is inserted into the connection hole of the terminal and the braid is located on the holding means so as to position the conductor relative to the terminal and the braid relative to the shield cover at one time, and the second lid is then closed to cooperate with the first lid to hold the insulator therebetween. 
     Preferably, the connector further comprises a sleeve for receiving the terminal holder with the shield cover, the sleeve having a braid-holding means crimped on and connected to the braid located on the holding means. 
     Preferably, the holding means of the shield cover comprises a pair of opposed holding pieces having as a whole a shape equal to that of the insulator so as to get between the insulator and the braid on advancement of the coaxial cable toward the terminal. 
     Preferably, the first lid has at a side toward the holder body a terminal locking projection for locking the terminal in the holder body and at a side remote from the holder body a holding rib, and the second lid has at a side remote from the holder body a corresponding holding rib, the holding ribs of the first and second lids cooperating with each other to hold the insulator therebetween. 
     Advantageously, one of the holding ribs of the first and second lids has a locking indentation for pressing therein the insulator when the holding ribs of the first and second lids hold the insulator therebetween. 
     Advantageously, the second lid is lockingly engageable with the shield cover when the second lid is closed, through corresponding locking means provided on the second lid and the shield cover. 
     According to another aspect of this invention, there is provided a method of connecting a connector to a coaxial cable, the coaxial cable including a conductor, an insulator around the conductor, a braid around the insulator, and a sheath around the braid, which comprises the steps of: inserting a terminal into an insulating terminal holder, the terminal having a connection hole into which the conductor of the coaxial cable is inserted; locking the terminal in the terminal holder; mounting a conductive shield cover on the terminal holder, which shield cover has a holding means, such that the connection hole of the terminal and the holding means are longitudinally aligned with each other; and advancing the coaxial cable along a straight line toward the terminal to have the conductor inserted into the connection hole of the terminal and the braid located on the holding means so as to position the conductor relative to the terminal and the braid relative to the shield cover at one time. 
     Preferably, the method further comprises the step of soldering the conductor to the terminal at the connection hole. 
     Preferably, the method further comprises the step of inserting the terminal holder with the shield cover into a sleeve provided with a braid-holding means, and crimping the braid-holding means on the braid located on the holding means of the shield cover. 
     The above and other objects, features and advantages of this invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective of a connector for a coaxial cable according to one embodiment of this invention; 
     FIG. 2A is a perspective view of a terminal in FIG. 1, and FIG. 2B is a sectional view of the terminal; 
     FIG. 3A is a perspective view of a terminal holder in FIG. 1, with its upper and lower lids shown opened, and FIG. 3B is a sectional view of the terminal holder; 
     FIG. 4A is a perspective view of a shield cover in FIG. 1, and FIG. 4B is a sectional view of the shield cover; 
     FIG. 5A is a perspective view of a sleeve in FIG. 1, and FIG. 5B is a sectional view of the sleeve; 
     FIG. 6A is a perspective view of a holder-attached terminal assembled from parts in FIG. 1, and FIG. 6B is a sectional view of the holder-attached terminal; 
     FIG. 7A is a perspective view of the holder-attached terminal, with the upper lid shown closed, and FIG. 7B is a sectional view of the holder-attached terminal; 
     FIG. 8A is a perspective view of a cover-attached terminal assembled from more of the parts in FIG. 1, and FIG. 8B is a sectional view of the cover-attached terminal; 
     FIG. 9 is a sectional view taken along the line A—A of FIG. 8A; 
     FIG. 10 is a sectional view of the cover-attached terminal, with a coaxial cable being pushed therein; 
     FIG. 11 is a sectional view of the cover-attached terminal, with the coaxial cable fully pushed in; 
     FIG. 12 is a sectional view taken along the line B—B of FIG. 11; 
     FIG. 13A is a perspective view of a terminal-attached cable assembled from yet more of the parts in FIG. 1, and FIG. 13B is a sectional view of the terminal-attached cable; 
     FIG. 14 is a sectional view taken along the line D—D of FIG. 13A; 
     FIG. 15A is a perspective view of the terminal-attached cable being pushed in a sleeve in FIG. 1, and FIG. 15B is a sectional view of the terminal-attached cable; 
     FIG. 16 is a perspective view of the connector for a coaxial cable fully assembled from the parts in FIG. 16; 
     FIG. 17 is an exploded perspective view of a conventional connector for a coaxial cable; 
     FIG. 18 is a perspective view of a conventional terminal-attached cable; 
     FIG. 19 is a perspective view of a conventional connector-attached coaxial cable; 
     FIG. 20 is a view of another conventional connector for a coaxial cable, with its housing and the coaxial cable shown separated; and 
     FIG. 21 is a perspective view of the connector of FIG. 20, with the coaxial cable shown pushed into the housing. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of this invention will now be described with reference to the attached drawings. 
     FIGS. 1 to  16  show one embodiment of a connector for a coaxial cable according to this invention. 
     As shown in FIG. 1, a connector  1  for a coaxial cable  2  is made up of a conductive terminal  3  which connects to a conductor  2   a  of the coaxial cable  2 , an insulating terminal holder  4  for receiving the terminal  3 , a conductive shield cover  5  which protects the terminal holder  4 , and a conductive sleeve  6  which receives the terminal holder  4  and the shield cover  5  and connects to a braid  2   c  of the coaxial cable  2 . 
     The coaxial cable  2  consists of the conductor  2   a , an insulator  2   b  covering the outer periphery of the conductor  2   a , the braid  2   c  provided circumferentially around the outer periphery of the insulator  2   b , and an insulating sheath  2   d  covering the braid  2   c.    
     The terminal  3  as in FIGS. 1 and 2 is formed of a stamped conductive metallic plate. 
     The terminal  3  consists of a hollow terminal body  10  of rectangular cross section, a resilient contact  11  cut and raised from a bottom wall  10   a  of the terminal body  10 , connection pieces  12  stamped to project inwardly from both inclined walls  10   b  of the terminal body  10  for connection to a mating terminal (not shown), and an integral contact  13  extending outwardly at a rear end of the bottom wall  10   a . Incidentally, the terminal body  10  may be of arbitrary shape in cross section. 
     The contact  13  includes an extension plate portion  14  extending upwardly from the bottom wall  10   a  and a connection plate portion  15  integral with the extension plate portion  14 . The connection plate portion  15  is located substantially perpendicularly to an insertion direction P of the coaxial cable  2  into the terminal  3  and has a central connection hole  16 , so that the advancement of the coaxial cable  2  directly toward the connection hole  16  makes an automatic insert of the conductor  2   a  into the connection hole  16 . In this case, because the conductor  2   a , after its insertion into the connection hole  16 , needs not to be bent as in the described related art, the insertion operation can be done in a less time-and effort-consuming manner. 
     As shown in FIGS. 1 and 3, the terminal holder  4  consists of a cylindrical holder body  20 , and a pair of opposed upper and lower lids  21  and  22  hinged at the rear end of the holder body  20 . 
     The holder body  20  has a terminal receiving cavity  23  formed therein which receives through the rear end the terminal  3 . The holder body  20  has a pair of placement recesses  24 ,  24  formed on its outer periphery toward the rear end. There are a pair of locking grooves  25 ,  25  formed on respective placement recess bottom surfaces  24   a ,  24   a  which extend parallel to a center axis C of the holder body  20 . The holder body  20  is provided on its outer periphery at the front end with a pair of locking grooves  26 ,  26 . The holder body  20  has a flange  27  extending circumferentially inwardly at the front end, the flange having a central hole  27   a  for insertion therethrough of the not-shown mating terminal. 
     The upper and lower lids  21  and  22  are provided in the form of a cylinder divided into halves and are joined via respective hinges  28   a  and  28   b  to the rear end of the holder body  20  in an open/close manner. 
     The upper lid  21  consists of a split-cylinder-shaped body  30 , a holding rib  31  provided projecting on the inner surface  30   a  at the rear end of the body  30 , a pair of terminal locking projections  32  provided at the front end of the body  30 , and receiving cutouts  33  formed at both side edges of the body  30  toward the rear end. 
     On closing the upper lid  21 , the holding rib  31  is located transversely (substantially perpendicularly) to the center axis C of the holder body  20 . The holding rib  31  has a flat free (inner) end surface  31   a . The pair of opposed terminal locking projections  32  extend from the inner surface  30   a  at the front end of the upper lid body  30  so that on inserting the terminal  3  into the terminal receiving cavity  23  and closing the upper lid  21 , the pair of terminal locking projections  32  come into contact with the terminal  3  to lock same in the terminal receiving cavity  23 . The terminal  3  is thus prevented from slipping off rearwardly. 
     The lower lid  22  consists of a split-cylinder-shaped body  35 , a holding rib  36  provided projecting on the inner surface  35   a  at the rear end of the body  35 , stoppers  37  formed at the front end of the body  35 , cover-locking projections  38  provided at both sides of the body  35 , and a positioning groove  39  located on the outer periphery of the body  35 . 
     On closing the lower lid  22 , the holding rib  36  is located transversely (substantially perpendicularly) to the center axis C of the holder body  20 . The holding rib  36  has at the free (inner) end a locking indentation  36   a  of the same diameter as the insulator  2   b , so that on closing the upper and lower lids  21  and  22 , the insulator  2   b  is pressed by the inner end  31   a  of the holding rib  31  and fixed in the locking indentation  36   a  of the holding rib. The insulator  2   b  is thus prevented from positional deviation. 
     Each cover-locking projection  38  is longitudinally defined by slits  30   b  so that the projection  38  is deflectable relative to the lower lid body  35  in the direction transverse to the center axis C. The cover-locking projections  38  have integral cover-locking claws  38   a  projecting outwardly at their free end. 
     The stoppers  37  are for keeping the front end of the lower lid body  35  from contact with the rear end of the holder body  20  when the lower lid  22  is closed. 
     As shown in FIGS. 1 and 4, the shield cover  5  consists of a cover body  40  shaped like a half cylinder with a tapered rear end, a holder portion  41  located at the rear end, and locking claws (or ribs)  42  extending longitudinally on the inner surface at both lateral ends of the cover body  40 . It is designed that the cover body  40 , when assembled, has its intermediate portion cover the closed upper lid  21 , with its front end located on the holder body  20  at the rear end. 
     The holder portion  41  includes a pair of holder pieces  43 ,  43 , each with a slit  44 , projecting inwardly (downwardly on the drawing of FIG. 4B) at the rear end of the cover body  40 . The pair of holder pieces  43 ,  43  are provided in such an arrangement as to hold the insulator  2   b  therebetween and are spaced from each other by a distance equal to the diameter of the insulator  2   b . Consequently, if the coaxial cable  2  is inserted from the rear end side of the cover body  40 , the pair of holder pieces  43 ,  43  slide on the insulator  2   b  and advance in between the insulator  2   b  and the braid  2   c , thereby making it possible to position the braid  2   c  relative to the cover body  40 . 
     In this case, if the pair of holder pieces  43 ,  43  are sharpened (angled acutely) at the side toward the incoming coaxial cable  2 , their insertion in between the insulator  2   b  and the braid  2   c  will be more easily attained, such pair of holder pieces  43 ,  43  successfully raising the braid  2   c  from the insulator  2   b.    
     As will be later described, the locking claws  42  of the shield cover  5  engage in the respective locking grooves  25  formed on the holder body  20  and engage with the respective cover-locking claws  38   a  of the lower lid  22  when the lower lid  22  is in closed position. The cover-locking projections  38  are deflected inwardly to bring their cover-locking claws  38   a  into engagement with their respective locking claws  42  (FIG.  14 ). 
     As shown in FIGS. 1 and 5, the sleeve  6  includes a sleeve body  50  made up of a cylindrical portion  51  and a trough-shaped portion  52  extending at the rear end of the cylindrical portion  51 , a pair of braid-holding pieces  53 ,  53  and a pair of sheath-holding pieces  54 ,  54  provided upright at the trough-shaped portion  52  of the sleeve body  50 , the latter located on an outer side in the insertion direction P of the coaxial cable  2 , a holder-positioning piece  55  provided at the trough-shaped portion  52 , holder-locking pieces  56  formed at the cylindrical portion  51  of the sleeve body  50 , and a collar  57  provided circumferentially around the sleeve body  50  at the front end. Inside the cylindrical portion  51  is formed a terminal receiving space  58  for receipt therein of the mating terminal. 
     The holder-locking pieces  56  engage in the respective locking grooves  26  of the holder body  20  and the holder-positioning piece  55  engages in the positioning groove  39  of the closed lower lid  22 , so that the terminal holder  4  is reliably locked in position in the sleeve  6 . 
     The method of connecting the connector  1  to the coaxial cable  2  will now be described. 
     The sheath  2   d  is stripped off at one end of the coaxial cable  2  to have the conductor  2   a , the insulator  2   b  and the braid  2   c  exposed as shown in FIG.  1 . 
     A holder-attached terminal  7 , as shown in FIGS. 6A and 6B, is provided by inserting the terminal  3  into the terminal receiving cavity  23  of the terminal holder  4  whose upper and lower lids  21  and  22  are opened. The upper lid  21  alone is then closed so that its pair of terminal locking projections  32 ,  32  abut against the terminal  3 . The terminal  3  is thus locked in the terminal holder  4  and prevented from coming off rearwardly of the holder body  20 . 
     A cover-attached terminal  8 , as shown in FIGS. 7A,  7 B,  8 A and  8 B, is then provided by pushing, with the lid  21  closed, the shield cover  5  along the placement recesses  24  and engaging the locking claws  42  provided at both lateral ends of the cover body  40  in the respective locking grooves  25  (FIG.  9 ). The front end of the cover body  40  is thus mounted on the rear end of the holder body  20 , with its intermediate portion covering or superimposed on the upper lid  21 , at which time the holder pieces  43  and the holding rib  31  of the upper lid  21  are longitudinally aligned with each other. 
     The coaxial cable  2 , as shown in FIG. 10, is then pushed from the rear end side of the shield cover  5  toward the connection hole  16 . As shown in FIGS. 11 and 12, the conductor  2   a  advances through between the pair of holder pieces  43 ,  43  (FIGS. 4A,  4 B) into the connection hole  16 . As the conductor  2   a  advances into the connection hole  16 , the pair of holder pieces  43 ,  43  slide on the insulator  2   b  to get under and circumferentially raise the braid  2   c , i.e., the pair of holder pieces  43 ,  43  are inserted in between the insulator  2   b  and the braid  2   c . The conductor  2   a  and the braid  2   c  are thus positioned relative to the cover-attached terminal  8  at one time. At this time, the lower lid  22  is still in opened position. 
     Thereafter, a terminal-attached cable  9 , as shown in FIGS. 13A and 13B, is produced by electrically connecting the conductor  2   a  to the terminal  3  at the connection hole  16  through soldering and closing the lower lid  22 . On closing the lower lid  22 , its cover-locking projections  38  deflects inwardly until they enter the receiving cutouts  33  and have their cover-locking claws  38   a  engaged with the respective locking claws  42  of the shield cover  5  (FIG.  14 ), at which time the holding rib  36  and the holding rib  31  hold the insulator  2   b  therebetween. The soldered connection  17  between the conductor  2   a  and the terminal  3  is located inside the closed upper and lower lids  21  and  22 , with the insulator  2   b  held between the holding ribs  36  and  31  as mentioned above, and thus a reduction is made in the load on the conductor  2   a  during a subsequent operation or process. As a result, an improved reliability is attained in the electrical connection between the conductor  2   a  and the terminal  3 . 
     As shown in FIGS. 15A and 15B, the terminal-attached cable  9  is pushed, with the terminal  3  side first, into the terminal receiving space  58  of the sleeve  6  until the locking grooves  26  engage the holder-locking pieces  56  and the positioning groove  39  engages the holder-positioning piece  55 , thereby to assemble the terminal-attached cable  9  to the sleeve  6 , at which time the outer surface  40   a  at the front end of the shield cover  5  comes into contact with the inner surface  51   a  of the cylindrical portion  51  of the sleeve  6  to make an electrical connection between the shield cover  5  and the sleeve  6 . 
     As shown in FIG. 16, the pair of braid-holding pieces  53 ,  53  and the pair of sheath-holding pieces  54 ,  54  are crimped on the braid  2   c  and the sheath  2   d , respectively, of the terminal-attached cable  9 . The braid  2   c  is thus electrically connected to the sleeve  6 , and the sheath  2   d  is mechanically connected to the sleeve  6 , thereby to connect the connector  1  to the coaxial cable  2 . 
     With this connection method, as described in connection with FIGS. 6 to  16 , because the conductor  2   a  and the braid  2   c  are positioned at one time to provide the terminal-attached cable  9 , and the terminal-attached cable  9  is thereafter assembled into the sleeve  6  as a single unit, the connector  1  is connected to the coaxial cable  2  in a simplified manner as compared with the described related art, making it possible to automate the connecting operation or process and attain an improved production efficiency. 
     Further, because load is prevented from being applied on the conductor  2   a  during and after connection of the connector  1 , greater reliability is attained in the electrical connection between the conductor  2   a  and the terminal  3  than before. The product is thus maintained high quality. 
     Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit and scope of the invention as set forth herein.