Patent Publication Number: US-7210954-B2

Title: Electrical connector plug with lock screws

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a plug for an electrical connecter with lock screws, for example, configured in a way that a connection condition is firmly maintained by screw clamping. 
   2. Related Art 
   In an electrical connecter having a metal shell to protect against EMI and which is used for connection of a personal computer, LAN device, measuring instrument or the like, an insulative connector housing is covered with a metal shell as an electrical shield, and electrical connection between respective shells at a receptacle side and a plug side of the electrical connector is established by directly contacting parts of the shells to each other. As a receptacle mounted on a printed circuit board, a receptacle is known, in which a metal shell is electrically connected by a screw, to a conductive nut fitted in a through-hole of a housing body of the receptacle and a metal sheet member, and when the receptacle is mounted on the printed circuit board, the shell is grounded to a conductive portion of the relevant printed circuit board (refer to JP-U-5-72069). 
   However, since a plug to be connected to the receptacle for the electrical connector is of a structure where the electrical connection is established by contacting the shells to each other when contacts are engaged with each other, an electrical connection condition of the plug is not necessarily secure, and may deteriorate due to aging. Furthermore, even in a type of an electrical connector with a lock screw, while mechanical connection between the receptacle and the plug is secure and firm by the screw and a nut, connection between respective shells of the receptacle and the plug is made by partially butting the relevant shells against each other, which is insufficient in secureness. 
   SUMMARY OF THE INVENTION 
   In view of the above problems in the conventional plug, an object of the invention is to provide an electrical connector plug with lock screws in which, in the receptacle and the plug of the electrical connector, a secure electrical conduction path can be ensured in addition to an electrical conduction path by direct contact between the shells for covering the connector housings. 
   Thus, an electrical connector plug according to the invention is configured to include an insulative connector housing having a rectangular body on which contacts are arranged, and locking sections extending out to two lateral portions of the body, metal lock screws inserted through screw holes formed in the locking sections, and a metal shell for electrically covering the connector housing; wherein the shell covers the locking sections, and through-holes for inserting the lock screws are formed in the shell in positions facing the screw holes, and a contact surface against which the relevant lock screw partially contacts is secured for electrical shielding around one side of each of the through-holes. 
   The screw holes in the locking sections are preferably configured in a way such that, when the lock screws are inserted through the holes, front ends of the lock screws act as taps to form thread grooves. 
   According to the electrical connector plug of the invention, once the relevant electrical connector plug is fitted in an electrical connector receptacle as the other connector and thus connected to the receptacle, and the lock screws are clamped in nuts at a side of the receptacle, the shell covering the body comes into contact with a shell of the electrical connector receptacle and is thus electrically connected thereto, and firm connection is achieved through clamping the lock screws with the nuts at the receptacle side. The lock screws are clamped respectively in the locking sections of the connector plug, such that a part of the relevant lock screw such as an end face of a grip of the lock screw or washer tightly contacts against a contact surface around a through-hole of the shell that covers a front side of the locking section, and consequently the shell, lock screw, and nut at the receptacle side are electrically connected. The shell at the receptacle side is electrically connected to the nut, and the shell at the plug side is electrically connected to the shell at the receptacle side therethrough. The shell at the receptacle side is grounded to the ground of a printed circuit board, and the whole electrical connector including the plug and the receptacle is electrically shielded therethrough. 
   In this way, for the receptacle and the plug for the electrical connector, a secure electrical conduction path is newly ensured by the lock screw and the nut in addition to the electrical conduction path by direct contact between the shells for covering the connector housings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1A ,  1 B,  1 C and  1 D are plan, front, back and right side views showing respectively an electrical connector plug with lock screws, according to an embodiment of the invention; 
       FIGS. 2A ,  2 B,  2 C,  2 D and  2 E are plan, front, back, right side and bottom views showing respectively a connector housing of the electrical connector plug of the embodiment; 
       FIGS. 3A ,  3 B,  3 C,  3 D and  3 E are plan, front, back, right side and bottom views showing an upper shell of the electrical connector plug of the embodiment; 
       FIGS. 4A ,  4 B,  4 C,  4 D and  4 E are plan, front, back, right side and bottom views showing respectively a lower shell of the electrical connector plug of the embodiment; 
       FIGS. 5A ,  5 B,  5 C,  5 D and  5 E are plan, front, back, right side and bottom views showing respectively a condition where upper and lower shells are attached a connector housing; 
       FIG. 6  is a cross section view along a line  6 — 6  in  FIG. 5A ; 
       FIG. 7A  is a cross section view partially showing an aspect that the electrical connector plug is subjected to insert-molding; 
       FIG. 7B  is a cross section view of the connector plug after the molding; 
       FIG. 8  is a cross section view showing a use situation of the electrical connector plug of the embodiment; 
       FIG. 9  is a cross section view partially showing the use situation of the electrical connector plug of the embodiment; and 
       FIG. 10  is a cross section view showing a use situation of an electrical connector plug with lock screws according to another embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As shown in  FIG. 1A  to  FIG. 1D , an electrical connector plug  1  according to an embodiment of the invention generally includes an insulative synthetic-resin connector housing  2 ; a plurality of contacts  3  lined on the connector housing  2 ; an upper shell  4  and a lower shell  5  for electrically covering the connector housing  2 ; a cable  6  having a shielded wire (braded net wire) that is folded back to the outside of the cable and then fixed to a clasp  5   a  of the lower shell  5  by calking; metal lock screws  7  inserted through screw holes  2   c  provided in locking sections  2   b  in lateral portions of the connector housing  2 ; and a housing cover  8  and a cable cover  9 , which are formed by insert molding such that they partially cover the locking sections  2   b  and the upper and lower shells  4  and  5 , and cover an end portion of the cable  6 . 
   As shown in  FIGS. 2A to 2E , the connector housing  2  has a central, rectangular body  2   a , and locking sections  2   b  extending out from rear ends of the body to both sides. A front end of the body  2   a  is a portion to be attached to a fitting portion of a receptacle as another connector, on which contacts  3  for connection are disposed parallel to one another. In the locking sections  2   b , screw holes  2   c  running through the sections in a back and forth direction are formed respectively. A portion having a reduced hole-diameter is formed at a rear end side of each screw hole  2   c , and when the metal lock screw  7  is first inserted through the screw hole  2   c , a front end of the lock screw acts as a tap to form a thread groove. Therefore, after the lock screw  7  is screwed into the screw hole  2   c  and then inserted through the hole, it is retained and held by the relevant lock screw hole  2   c.    
   The upper shell  4  and the lower shell  5  cover the body  2   a  and the locking sections  2   b  of the connector housing  2 , and are integrally molded as shown in  FIG. 3A  to  FIG. 4E . Holes  4   a  and  5   b  for inserting the lock screws  7  are formed in portions for covering the locking sections  2   b  respectively. 
   As shown in  FIG. 5A  to  FIG. 6 , the upper shell  4  and the lower shell  5  are attached to the connector housing  2  to cover the housing, and then the cable  6 , having element wires respectively connected to the contacts  3 , is run through the clasp  5   a  of the lower shell  5 , and then the braded net wire is folded back to the outside and then fixed to the clasp by calking. 
   Next, the connector plug  1  in a condition where the shells  4 ,  5  and the cable  6  are attached to the connector housing  2  is disposed in a die  10  as shown in  FIG. 7A . At that time, the die  10  is designed such that the screw hole  2   c  and the hole  4   a  are not plugged in the locking section  2   b  of the connector housing  2 , and a contact surface  4   b  is secured around the hole  4   a  so that an end face  7   a  of a grip of a lock screw  7  can contact against an extended portion of the upper shell  4 . 
   In addition to this, a case in which the contact surface  4   b  is secured by a spring strip folded inside the hole  4   a  is also acceptable. In this case, part of the lock screw  7  may include a flange integrated with the lock screw, or a separate washer, pipe or the like fitted with the relevant lock screw. 
   Then, melted resin is caused to flow into a cavity of the die to form a housing cover  8  and a cable cover  9 . In this way, the electric connector plug  1  is completed. In usage of the plug  1 , as shown in  FIG. 8 , for example, the plug is connected to a connector receptacle  11  as the other connector in a modular arrangement, wherein the contacts  3  of the plug  1  are connected to contacts  11   a  at a receptacle side, and the shells  4 ,  5  at a plug  1  side contact against a shell  11   b  and the like at the receptacle  11  side and are thus connected thereto, and consequently grounded to the ground of a printed circuit board  12  on which the receptacle  11  is mounted. 
   Furthermore, as shown in  FIG. 9 , the lock screw  7  is clamped to a lock nut  13  of the receptacle as the other connector. In this manner, the end face  7   a  of the grip firmly contacts against the contact surface  4   b  of the upper shell  4 , and the front end  7   b  of the lock screw is connected to a nut  13  of a locking section  11   d  at the receptacle side. The nut  13  contacts against a shell  11   c  at the receptacle side and is thus connected thereto. As a result, the shell  4  is electrically connected to the shell  11   c , resulting in formation of an electrical shield. In this way, in addition to a shield path by direct contact between the shells  4  and  11   c , a shield path via the lock screw  7  and the nut  13  is formed, which guarantees secureness. When a panel  14  is interposed between the plug and the receptacle as shown in  FIG. 10 , an offset screw  15  is preferably disposed at a front-end side of the lock screw  7  for screw clamping. Thus, a new shield path is secured by the lock screw  7  and the nut  13  as in the case of  FIG. 9 .