Abstract:
An electrical connector includes a plurality of contacts  16 , a housing  12  for holding and fixing the contacts  16  therein and having a fitting portion  24  with which a mating object is fitted, and two shells  20  and  22  covering the housing  12 . One shell  20  of the two shells comprises at a predetermined position with respect to its longitudinal direction a required number of substantially L-shaped engagement portion  23  integrally formed on the one shell  20 . With this construction, even with an electrical connector of miniaturization of height of less than  2  mm, it is possible to provide a connector  10  whose shells  20  and  22  are prevented from being deformed due to undue forces accidentally acting upon the coaxial cables  14.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an electrical connector for use with notebook personal computers, small type digital appliances and the like, and more particularly to a connector having a construction for preventing shells from being deformed. 
   In general, a hitherto used electrical connector mainly comprises a housing, a required number of contacts, and shells. The contacts are held and fixed in the housing which has a fitting portion adapted to be fitted with a mating connector. The shells are fixed to the housing so as to cover it. 
   Japanese Utility Model Application Opened No. H4-92,384/1992 discloses an electrical connector. As can be seen from the “Abstract” of the Japanese Utility Model Application, metal shells are fixed to an insulating block by fitting anchoring projections formed on the insulating block into anchoring apertures formed in fixing tongues provided on the metal shells for the purpose of preventing the metal shells of a receptacle connector from being deformed when a plug connector is fitted into the receptacle connector. To achieve such a purpose, there are provided means for securing the centers of the metal shells  6  with respect to their longitudinal direction, which are inferior in mechanical strength, to the insulating block, or means for avoiding application of forces causing deformation at the centers of the metal shells  6  with respect to their longitudinal direction when fitting the plug connector into the receptacle connector. In more detail, the Utility Model discloses deformation preventing means, such as (1) engagement of anchoring tongues with anchoring steps or shoulders on the side of fitting portion of the connectors, (2) connection of the shells on the side of the fitting portion of the connectors, (3) insertion of fixing inserting tongues into tong receiving apertures on the side of connection portion, and (4) calking. 
   Depending upon spaces in appliances and applications and specifications or customer&#39;s demands, however, the means described above could not be employed. With an electrical connector of lower geometry or miniaturization of height of less than 2 mm, particularly, the construction described above would be impossible. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to provide an improved electrical connector which overcomes the disadvantages of the prior art described above and which is able to prevent shells from being deformed even with miniaturization of height of less than 2 mm. 
   The above object can be achieved by the electrical connector  10  including a plurality of contacts  16 , a housing  12  for holding and fixing the contacts  16  therein and having a fitting portion  24  with which a mating object is fitted, and two shells  20  and  22  covering the housing  12 , wherein one shell  20  comprises at a predetermined position with respect to its longitudinal direction a required number of substantially L-shaped engagement portion  23  integrally formed on the one shell  20  according to the invention. 
   In a preferred embodiment of the invention, the substantially L-shaped engagement portion  23  is provided on the one shell  20  in the proximity of substantially center with respect to its longitudinal direction. By providing the engagement portion in such a position, the shells  20  and  22  are prevented from being deformed in a well-balanced manner. 
   In another embodiment of the invention, the substantially L-shaped engagement portion  23  integrally formed on the one shell  20  in the direction of its thickness is brought into engagement with the other shell  22 . With such an engagement, the shells are prevented from being deformed. 
   As can be seen from the above descriptions the electrical connector  10  according to the invention can bring about the following significant effects.
     (1) In the electrical connector  10  including a plurality of contacts  16 , a housing  12  for holding and fixing the contacts  16  therein and having a fitting portion  24  with which a mating object is fitted, and two shells  20  and  22  covering the housing  12 , according to the invention one shell  20  comprises at a predetermined position with respect to its longitudinal direction a required number of substantially L-shaped engagement portion  23  integrally formed on the one shell  20 . Therefore, even with an electrical connector miniaturized in height of less than 2 mm, it is possible to provide a connector  10  in a simple construction whose shells  20  and  22  are prevented from being deformed due to undue forces accidentally acting upon coaxial cables  14 .   (2) According to the invention, the substantially L-shaped engagement portion  23  is provided on the one shell  20  in the proximity of substantially center with respect to its longitudinal direction. Therefore, the shells  20  and  22  are prevented from being deformed in a well-balanced manner.   (3) According to the invention, the substantially L-shaped engagement portion  23  integrally formed on the one shell  20  in the direction of its thickness is brought into engagement with the other shell  22 . As a result, the shells  20  and  22  are prevented from being deformed with great certainty when the coaxial cables  14  are accidentally subjected to undue forces.   

   The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of an electrical connector according to the invention; and 
       FIG. 2  is a perspective view of the electrical connector shown in  FIG. 1  with the two shells separated from the housing of the connector. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   An electrical connector  10  of one embodiment according to the invention will be explained with reference to the drawings hereinafter.  FIG. 1  is a perspective view of the electrical connector according to the invention.  FIG. 2  is a perspective view of the electrical connector according to the invention with two shells separated from each other. The electrical connector  10  according to the invention mainly comprises a housing  12 , contacts  16 , shells  20  and  22 , and a ground bar  18 . 
   Before explaining respective components of the connector, first, the construction of coaxial cables  14  will be explained. The coaxial cables  14  each mainly comprise a center conductor  141 , an insulator  142 , a braid  143  as an external conductor, and a sheath  144 . Note that the details are not shown in the drawing. The center conductor  141  made of a metal is adapted to be connected to the contact  16  and covered by the insulator  142  thereabout. The insulator  142  serves to insulate the center conductor  141  from the braid  143  as an external conductor. The insulator  142  is covered by the braid  143  as the external conductor. The braids  143  are connected to the ground bar  18  to provide the grounding and each covered therearound by the sheath  144  made of an insulating material such as vinyl chloride. 
   Prior to being connected to the contacts  16 , the coaxial cables  14  are pre-treated in the following manner. First, the sheath  144  is removed over a predetermined length, and the leading end of the insulator  142  is then removed to expose the center conductor  141  of a predetermined length. Finally, the braid  143  is partly removed to leave the braid of a predetermined length, while taking care enough to avoid any contact between the center conductor  141  and the braid  143 . 
   The respective components of the connector  10  according to the invention will be explained with reference to the drawings. First, the two shells  20  and  22  will be explained which are the subject features of the invention. As shown in  FIG. 2 , the two shells  20  and  22  are arranged one above the other. These shells  20  and  22  are made by the publicly known press-working from a metal such as beryllium copper, phosphor bronze, brass and the like to fulfil the requirements imposed thereon, such as dimensional stability, workability and conductivity. The two shells  20  and  22  are substantially U-shaped and fixed to the housing  12  by press-fitting or hooking or latching in a manner covering the housing  12 . In the illustrated embodiment, the shells  20  and  22  are each provided with anchoring pieces  36  at longitudinal ends for fixing the shells  20  and  22  to the housing by hooking. 
   In the illustrated embodiment, the shells may be formed with a required number of mating connector contact pieces  38  and a required number of ground bar contact pieces  40  for the purpose of achieving continuity with the mating connector and providing the grounding with the ground bar  18  depending on specifications or customer&#39;s demands. In forming both the contact pieces, the shells  20  and  22  in the working course of them may be formed with slits around the predetermined positions of the contact pieces  38  and  40 , leaving part of the slits, and the contact pieces are raised or bent in a cantilevered manner. As a result, the contact pieces  38  and  40  have an elasticity for preferably contacting the mating connector and the ground bar  18 . 
   The shells  20  and  22  and the housing  12  fitted together form an inserting groove  30  on the side of connection portion for inserting a required number of coaxial cables  14 . The shell  20 , one of the two shells is integrally formed with a plurality of L-shaped engagement portions  23  in order to prevent the shells  20  and  22  from being deformed when the coaxial cables  14  inserted in the inserting groove  30  are unduly subjected to forces accidentally on the side of the inserting groove  30 . The L-shaped engagement portions  23  integrally formed on the shell  20  have a free end which engages the main body of the other shell  22  to prevent the deformation of the shells  20  and  22 . The number of the engagement portions  23  is suitably designed in consideration of their function, the number of the cables, and the size of the connector. A single engagement portion is of course within the range of the present invention. In the illustrated embodiment of the connector  10  having thirty coaxial cables and of 26 mm in length, 8 mm in width and 1.9 mm in height, the two engagement portions  23  are arranged substantially at the middle of the shell  20  and 3 mm spaced apart from each other. 
   The size of the shells  20  and  22  may be suitably designed to achieve their function. In the illustrated embodiment, the shell  20  is 22 mm in length, 5.6 mm in width and 0.8 mm in thickness, and the shell  22  is 22.3 mm in length, 5.1 mm in width and 0.9 mm in thickness. 
   Although the engagement portions  23  are provided on the lower shell  20  as viewed in  FIG. 2 , it is to be understood that the engagement portions  23  may be provided on either of the shells  20  and  22 . Therefore, the engagement portions  23  may be provided on the upper shell  22 , which are adapted to engage the lower shell  20 . 
   The housing will then be explained. The housing  12  is made by the publicly known injection molding from an electrically insulating plastic material which is suitably selected in consideration of dimensional stability, workability, manufacturing cost and the like. Preferred materials from which to form the housing  12  include polybutylene terephthalate (PBT), polyamide (66 PA or 46 PA), liquid crystal polymer (LCP), polycarbonate (PC), polyphenylene sulfide (PPS) and the like and combination thereof. 
   The housing  12  is substantially bar-shaped having a protrusion whose front end forms a fitting portion  24  which extends beyond the shells  20  and  22  for fitting with a mating connector. Contacts  16  are installed in the fitting portion  24  such that contact portions  161  of the contacts  16  are exposed on both the sides of the fitting portion  24 . The housing  12  is further formed with inserting holes  34  for inserting a required number of the contacts  16  therein and fixing thereat by press-fitting, hooking (lancing), welding or the like, respectively. Moreover, the housing  12  is formed with anchoring grooves  35  at locations corresponding to the anchoring pieces  36  of the shells  20  and  22  so that the shells  20  and  22  are fixed to the housing  12  by the engagement of the anchoring pieces  36  in the anchoring grooves  35  of the housing  12 . 
   The housing is further provided with a plurality of protrusions  32  in the form of teeth of a comb for arranging the coaxial cables  14  in a row as shown in  FIG. 2 . The size of the protrusions  32  may be suitably designed in consideration of their function, diameter and pitch of the coaxial cables  14  and the like. In the illustrated embodiment, the protrusions  32  are of the order of 0.3 mm in height, 0.3 mm in width and 0.4 mm in length. 
   The housing  12  is provided with a mounting portion  26  communicating with the inserting holes  34 , and an inserting portion  28  communicating beyond the protrusions  32  with the mounting portion  26 . The center conductors  141  of the coaxial cables  14  are connected to connection portions  163  of the contacts  16  in the mounting portion  26 , respectively. The inserting portion  28  serves to receive therein the ground bar  18 . The size of the inserting portion  28  may be suitably designed in consideration of the size of the ground bar  18  and the strength of the housing, and is approximately 0.1 mm larger than the ground bar  18  in the illustrated embodiment. 
   The contacts  16  will then be explained. The contacts  16  in the illustrated embodiment include power supply contacts and signal contacts. These contacts are made by the publicly known press-working from a metal such as beryllium copper, low-beryllium copper, phosphor bronze and the like to fulfil the requirements imposed thereon such as conductivity, springiness, dimensional stability and the like. Each of the contacts  16  mainly comprises a contact portion  161  adapted to contact a mating contact, a fixed portion  162  (not seen in the drawing) to be fixed to the housing  12 , and a connection portion  163  to be connected to a coaxial cable  14 . 
   Finally, the ground bar  18  will then be explained. The ground bar  18  is made by the publicly known press-working from a metal which may be beryllium copper, low-beryllium copper, phosphor bronze and the like in consideration of conductivity, dimensional stability and the like. The ground bar  18  is substantially a plate-shaped piece and is connected to the braids  143  of coaxial cables  14  by soldering to provide the grounding for the coaxial cables  14 . Moreover, the contact pieces  40  of the shell  22  are brought into contact with the ground bar  18  to provide the grounding for the shell  22  and simultaneously for the coaxial cables  14 . The ground bar  18  operates to embrace the braids  143  of the coaxial cables  14 , thereby providing the grounding for the coaxial cables  14 . The size of the ground bar  18  depends upon the number and pitch of the coaxial cables. In the illustrated embodiment with the thirty coaxial cables and 0.5 mm pitch, the ground bar has a length of 19 mm. 
   The present invention is preferably applicable to connectors for use with notebook personal computers, small type digital appliances and the like. Particularly, the electrical connector  10  according to the invention has a preferable construction for preventing the shells  20  and  22  from being deformed. 
   While the invention has been particularly shown and described with referenced to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes is form and detail can be made therein without departing from the spirit and scope of the invention.