Abstract:
In a connector to be mounted on a circuit board having a ground pattern, a connecting member is assembled to a housing holding a contact. The connecting member has conductivity for electrically connecting with the ground pattern. A shell is coupled to the housing and is for electro-magnetically shielding the contact. The shell includes first and second shells. The first shell has conductivity and assembled to the housing in a fitting direction of the connector to surround a contact portion of the contact. The second shell has conductivity and assembled to the housing in a particular direction orthogonal to the fitting direction. The second shell covers a terminal portion of the contact and clamps the housing and the connecting member in the fitting direction. The first shell is in contact with the second shell and is fixed to the connecting member.

Description:
This application claims priority to prior Japanese patent application JP 2003-145379, the disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   This invention relates to a connector and, in particular, to a connector having an electromagnetic shielding function. 
   In recent years, an electronic apparatus such as a computer, a server, and an exchange is remarkably wide spread. Since the electronic apparatus of the type transmits a high-speed electronic signal, a connector used as an I/O port of the apparatus is desired to have an electromagnetic interference protection. 
   Unlike ordinary electronic components, the connector can not entirely be covered with a shielding case for protection against electromagnetic interference. If the connector is entirely covered with the shielding case, the connector can not achieve electrical and mechanical connection with a mating object to be connected. Under the circumstances, it is desired for the connector to be enhanced in electromagnetic shielding function without being entirely covered with the shielding case. 
   For example, Japanese Patent Application Publication (JP-A) No. H7-192813 discloses a connector comprising a connector body covered with a metal shell. Japanese Patent Application Publication (JP-A) No. 2002-231391 (corresponding to U.S. Pat. No. 6,629,859) discloses a connector in which a housing and a contact held by the housing are covered with a front shell and a back shell each of which is made of metal. 
   In these connectors, the shell can be connected to the housing by the use of a caulking or staking technique. However, the caulking technique requires a caulking tool and a caulking operation. As a consequence, it is troublesome to assemble and disassemble the connector. In addition, a production cost is inevitably increased. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a connector in which a shell can be fixed to a housing without using a caulking technique. 
   Other objects of the present invention will become clear as the description proceeds. 
   According to aspect of the present invention, there is provided a connector to be mounted on a circuit board having a ground pattern, the connector comprising a contact made of a conductive member and having a contacting portion and a terminal portion, a housing holding the contact and defining a fitting direction of the connector, a shell coupled to the housing for electro-magnetically shielding the contact, and a connecting member assembled to the housing and having conductivity for electrically connecting with the ground pattern. The shell comprises a first shell having conductivity and assembled to the housing in the fitting direction to surround the contacting portion of the contact and a second shell having conductivity and assembled to the housing in a particular direction orthogonal to the fitting direction, the second shell covering the terminal portion of the contact and clamping the housing and the connecting member in the fitting direction, the first shell being in contact with the second shell and being fixed to the connecting member. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1A  is a perspective view of a connector according to one embodiment of the present invention as seen from a front side; 
       FIG. 1B  is a perspective view of the connector in  FIG. 1A  as seen from a rear side, with some components omitted for illustrating an internal mechanism; 
       FIG. 2  shows an assembling process of the connector illustrated in  FIGS. 1A and 1B ; 
       FIG. 3  is an exploded perspective view of a characteristic part of the connector, having a section taken along a line III—III in  FIG. 1A ; 
       FIG. 4A  is an exploded perspective view similar to  FIG. 3 , having a section taken along a line IV—IV in  FIG. 1A ; and 
       FIG. 4B  is a right side view of the characteristic part illustrated in  FIG. 4A . 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring to  FIGS. 1A ,  1 B, and  2 , description will at first be made of an entire structure of a connector according to one embodiment of the present invention. 
   The connector depicted at  1  in the figure comprises an insulating housing  2 , a plurality of conductive contacts  3  held by the housing  2  and arranged in a first direction A 1  which is referred to as a particular direction, a shell  4  for electro-magnetically shielding the contacts  3 , and a pair of conductive earth lugs  5  as a connecting member to be connected to a conductive ground pattern of a board or substrate (not shown) such as a circuit board. The contacts  3  are extends parallel to one another in second and third directions A 2  and A 3  which are orthogonal to the first direction A 1  and orthogonal to each other. The second direction A 2  is referred to as a fitting direction. 
   Each of the contacts  3  is made of a conductive member such as a metal plate and has a contacting portion (not shown) formed at one end and a terminal portion  3   a  formed at the other end. The contacting portions of the contacts  3  are positioned inside a protruding portion  2   a  at a front side of the housing  2  and arranged in eight columns and three rows. The terminal portion  3   a  of each contact  3  protrudes from a rear surface of a main body  2   b  of the housing  2  and is bent into a generally L-shaped configuration. The terminal portions  3   a  of the contacts  3  are held by a location plate  8  to be positioned and aligned. The earth lugs  5  are made of metal material and are fixed to the housing  2  by the use of a pair of receiving portions  2   c  formed at left and right sides of the housing  2 . 
   The shell  4  comprises a conductive first shell, i.e., a front shell  6  covering the contacting portions of the contacts  3  and a conductive second shell, i.e., a back shell  7  covering the terminal portion of the contacts  3 . Each of the front shell  6  and the back shell  7  is made of a metal plate. A fixing structure of the front shell  6  and the back shell  7  to the housing  2  will later be described. 
   The front shell  6  has a cylindrical portion  6   a  fitted to an outer peripheral surface of the protruding portion  2   a  of the housing  2 , a front plate portion  6   b  covering a front surface of the main body  2   b  of the housing  2 , a pair of side plate portions  6   c  covering opposite side surfaces of the main body  2   b , and a pair of terminal portions  6   d  protruding downward from the side plate portions  6   c , respectively. The front shell  6  is coupled with the housing  2  in the second direction A 2  and fixed to the housing  2 . 
   The back shell  7  has an upper plate portion  7   a  covering an upper surface of the main body  2   b  of the housing  2 , a rear plate portion  7   b  faced to the rear surface of the main body  2   b  with a space left therefrom, a pair of side plate portions  7   c  covering the opposite side surfaces of the main body  2   b , and a pair of terminal portions  7   f  formed at left and right sides of a lower edge of the rear plate portion  7   b . Each of the side plate portions  7   c  is for connecting to the ground pattern of the substrate. Before the front shell  6  is coupled with the housing  2 , the back shell  7  is coupled with the housing  2  in the third direction A 3 . 
   Particularly referring to  FIG. 2 , description will be made of assembling of the front shell  6  and the back shell  7  into the housing  2 . 
   At first, as illustrated in (a), the earth lugs  5  are fitted into the receiving portions  2   c  of the housing  2  in directions depicted by rearward arrows. Each of the earth lugs  5  is provided with a female thread  5   a  formed at its upper part and a generally L-shaped terminal portion  5   b  formed at its lower part. Each of the terminal portions  5   b  is connected to the ground pattern of the substrate. 
   Next, as illustrated in (b), the back shell  7  is coupled with the housing  2  in a direction depicted by a downward arrow. The back shell  7  has a pair of square plates  7   d  formed at front edges of the side plate portions  7   c  and extending in the first and the third directions A 1  and A 3 . Each of the square plates  7   b  has a circular hole  7   e.    
   Subsequently, as illustrated in (c), the front shell  6  is coupled with the housing  2  and the back shell  7  in a direction depicted by a rearward arrow. The front plate portion  6   b  of the front shell  6  has a pair of circular holes  6   e  formed at left and right sides thereof. 
   The connector  1  is fixed to a panel (not shown) in the following manner. At first, the cylindrical portion  6   a  is protruded through an opening formed in the panel. Next, a pair of screws (not shown) are inserted from a front side of the panel through corresponding holes formed in the panel and the circular holes  6   e  to be screwed into the female threads  5   a . Thus, the panel, the housing  2 , the front shell  6 , the back shell  7 , and the earth lugs  5  are integrally fixed. 
   Referring to  FIGS. 3 ,  4 A, and  4 B, description will be made of a linking structure of the housing  2 , the front shell  6 , the back shell  7 , the earth lugs  5 , and the location plate  8 . 
   The front shell  6  further has a contacting portion  6   f  formed at a center of an upper edge of the front plate portion  6   b  and bent rearward, and a pair of engaging portions  6   g  formed at left and right sides of a lower edge of the front plate portion  6   b  and bent rearward. The contacting portion  6   f  is elastically contacted with an upper surface of the upper plate  7   a  of the back shell  7 . The engaging portions  6   g  are engaged with the location plate  8 . Each of the terminal portions  6   d  is connected to the ground pattern of the substrate. 
   As described above, the terminal portions  7   f  are formed at the left and the right sides of the lower edge of the rear plate portion  7   b  of the back shell  7 . Each of the terminal portions  7   f  is connected to the ground pattern of the substrate. The terminal portions  5   b  of the earth lugs  5  are placed adjacent to the terminal portions  7   f  of the back shell  7  in the second direction A 2 , respectively. Therefore, adjacent ones of the terminal portions  5   b  and  7   f  can be connected commonly to a connecting portion, such as a through hole, a pad, or the like, which is connected to the ground pattern of the substrate. With this structure, the substrate is made compact and the connector  1  is simplified in structure. 
   The front shell  6  has a pair of engaging portions  6   h  engaged with a pair of engaging portions  2   d  formed on an upper side of the main body  2   b  of the housing  2 . The contacting portion  6   f  is contacted with the upper plate portion  7   a  of the back shell  7 . The engaging portions  6   g  are engaged with a pair of protruding portions  8   c  formed at left and right sides of a lower surface of the location plate  8 . 
   At each of both end portions in the first direction A 1 , the housing  2  has a groove  2   e  receiving a protruding portion  8   a  of the location plate  8  therein. The housing  2  has a hook  2   f  engaged with a hook  8   b  of the location plate  8 . 
   In the structure of this embodiment, the back shell is clamped by the front shell on an upper side of the connector. On left and right sides of the connector, the back shell is clamped between the earth lugs and the front shell. Thus, the front shell and the back shell are contacted with each other on three sides, i.e., the upper, the left, and the right sides of the connector. 
   The front shell is fixed by the screws to the panel having a grand voltage in the manner known in the art. Thus, a ground electric current uniformly covers the connector. It is therefore possible to achieve an excellent shielding effect and to prevent internal noise generated inside the connector from leaking outside. 
   Signal reflection as one of noise generating factors can be prevented by a loop structure (the panel→ the connector→ the substrate→ the panel) obtained by providing the front shell and the back shell with the terminal portions mounted to the substrate and connected to the ground pattern of the substrate. Therefore, it if possible to provide an image interface connector having a shielding function and suitable for EMI protection. 
   Since the back shell and the earth lugs can be connected through the same through holes formed in the substrate, the back shell and the earth lugs form a loop structure. Thus, a shielding structure capable of preventing signal reflection and facilitating flow of a ground signal. 
   While this invention has thus far been described in conjunction with the preferred embodiment thereof, it will be readily possible for those skilled in the art to put this invention into practice in various other manners without departing from the scope set forth in the appended claims.