Abstract:
A fastener for all-purpose power supplies sockets includes a socket and at least one plug engageable with the socket. The socket has a latch cavity in a lateral wall. The plug has a moveable fastening member that has a first button engaging with a latch bar. The latch bar has a latch head engageable with the latch cavity and a latch tail engageable with a spring strip. The latch head may engage with the latch cavity automatically when the plug is inserted in the socket to form a secure engagement and coupling. Upon moving the first button sideward, the latch head will be disengaged with the latch cavity to enable the plug to move away from the socket easily.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a fastener for all-purpose power supply sockets, and more particularly to a fastener including a moveable member for engaging or disengaging a plug from the socket easily. 
     2. Description of the Prior Art 
     A conventional all-purpose power supply socket usually has a common socket to support a variety of plugs, in which every plug has a first end to connect with the socket and a second end to connect with a power source. Generally, the all-purpose socket in the art includes a plug-type insert as a receptacle for electrically engaging with the first end of the plug. The second end of the plug may be embodied as a three-port plug, a two-port plug, a vertical-board type plug, or any plug type known in the art. 
     In conventional art, coupling of the socket and the plug is usually simply done by engaging the insert of the socket and the first end of the plug. U.S. Pat. No. 5,616,051 is one of such examples. Although such a type of engagement of the socket and the plug can provide a simple connection structure, yet it is quite possible that the engagement becomes looser and looser after long-term usage; especially after experiencing frequently engaging and disengaging operations. To remedy this problem, some fastening means between the socket and the plug have been introduced recently. U.S. Pat. No. 5,613,863 is one typical example for applying such fastening means. 
     However, the fastening means disclosed in U.S. Pat. No. 5,613,863 has an integrally formed plastic plug body (i.e., by associating part numbers 630,636 and 638 and the cavity 218). Due to the plastic material, the fastening means have limitation on applicable dimensions and deflection. It hence cannot be manufactured to a substantial size for facilitating manual operation. Also, because of material used and integral production property, it usually does not have enough strength to withstand fatigue fracture (e.g., it is prone to rupture at the root). 
     SUMMARY OF THE INVENTION 
     In view of aforesaid disadvantages, it is therefore an object of this invention to provide a fastener for all-purpose power supply sockets that has an independent fastening member to enable easy operation of a plug into a socket and making the whole unit more durable. 
     It is another object of this invention to provide an insert positioning means for the power supply socket that includes angular bulges and a recess to make assembly of the socket easier. 
     It is a further object of this invention to provide a socket conversion means to enable the insert of a plug having more than one type of outlet to suit different requirements. 
     The fastener according to this invention includes a socket and at least one plug. 
     The socket has a receptacle formed in a casing for receiving the plug. In the receptacle, there is provided with an insert that has a pair of terminals extending toward a top opening of the receptacle. 
     The plug has one end equipped with power terminals for coupling with an external power source and another end having slot-type openings for engaging with the receptacle. The slot openings, terminals and power terminals form an electric connection. 
     The fastening means according to this invention includes a latch bar located at the plug and a latch cavity located in a rear wall of the receptacle. The latch bar has a latch head formed at one end for engaging with the latch cavity, a latch tail formed at another end for engaging with a spring strip, and a first button located above the latch bar to enable a user in disengaging the latch head from the latch cavity when desired. 
     In one aspect of this invention, the latch cavity is formed in a wedge shape. The receptacle may have a transverse stop bar to prevent undesirable objects from entering in or making contact with the insert. 
     In another aspect of this invention, a conversion plug may be provided to engage with the receptacle. The conversion plug has slot openings at one end to couple with the terminals of the insert in the receptacle and a conversion socket formed at another end thereof for connecting with an external power source. The conversion socket, which is electrically connected with the slot openings, may be a socket of any standard specification. 
     In a further aspect of this invention, the insert may include an insert body pivotally engaged with the receptacle so that the insert may rotate in the receptacle. An angular means and a positioning means may be provided respectively to the insert body and the receptacle for enabling the insert to rotate among predetermined angles and to anchor at one of the angles. The positioning means may include a tongue-like member formed on the rear wall of the receptacle for providing an elastic engagement with the insert to facilitate rotation and positioning of the insert. The tongue-like member may be formed by cutting a U-shaped groove on the rear wall of the receptacle. Of course, other shape of groove may also be used. The positioning and angular means of this invention may be embodied as positioning bulges and an angular recess respectively, or vice versa (e.g., positioning recesses and an angular bulge respectively). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, as well as its many advantages, may be further understood by the following detailed description and drawings in which: 
     FIG. 1 is an exploded perspective view of a plug and a respective socket utilizing a fastener of this invention; 
     FIG. 2 is a fragmentary sectional view of a fastener of this invention; 
     FIG. 3 is an exploded view of an embodiment of the insert of the invention; 
     FIG. 4 is a perspective view of another embodiment of the socket of the invention; 
     FIG. 5 is a perspective view of a conversion socket of this invention; and 
     FIG. 6 is a fragmentary sectional view of the fastener shown in FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, the fastener of this invention includes a first fastening member  5  located in a plug  3  and a latch cavity  15  formed in a rear wall of a receptacle  11  located in a socket  1 . The socket  1  has a casing  10  housing the receptacle  11  therein and a power cable  17  at one end of the casing  10  for connecting with an electric device desired. 
     Beside the rear wall, the receptacle  11  has two side walls, a top opening and a front opening which has two side flanges  111  for holding the plug  33  securely in the receptacle  11 . Inside the receptacle  11 , there is an insert  13  which has a pair of spaced conductive terminals  131  that in turn have a bottom end electrically connecting with the power cable  17 . The terminals  131  may couple with the plug  3  vertically from the top opening as shown in FIG.  1 . The insert  13  may also be turned 90 degrees to have the terminals  131  laid horizontally to couple directly with an external power source through the front opening. 
     The plug  3  includes a power source end  31  upon which two or three power terminals  311  may be provided to couple with an external power source and a body  33  for being mounted into the receptacle  11 . At the bottom of the body  33 , there are slots (not shown in the figures) engageable with the terminals  131  to establish electrical connection between the external power source with the electric device through the power terminals  311 , terminals  131  and power cable  17 . At the engaged position, the first fastening member  5  engages with the latch cavity  15  as shown in FIG.  2 . Following description will offer more details of their structural relationship. 
     The first fastening member  5  is movable in a fastener slot  35  formed in a top wall of the body  33 . It has a first button  51  at the top thereof and a first latch bar  53  at the bottom. The first latch bar  53  further has a latch head  531  with a slant-in front side at one end and a latch tail  533  at another end. The latch tail  533  further engages with a spring strip  7  which is fixed to a first spring mounting  331  extended from the rear wall of the body  33 . 
     When the plug  3  is not in use and is separated from the socket  1  as shown in FIG. 1, the spring strip  7  restrains the latch bar  53  at the latch tail  533  to have the latch head  531  protruding out of the rear wall of the body  33 . 
     While sliding the body  33  of the plug  3  into the receptacle  11  of the socket  1 , the slant front side of the latch head  531  is firstly pushed by the rear wall to move the latch bar  53  backward against the spring strip  7 , and the latch bar  53  resumes its original state (as shown in FIG. 2) as soon as the latch head  531  engages with the latch cavity  15 . At the position shown in FIG. 2, the spring strip  7  presses the latch tail  533  to its original state so that the latch bar  53  may engage securely with the latch cavity  15 . The plug  3  thus may be held securely in the receptacle  11  of the socket  1 . 
     When there is a need to disengage the electric device from the power source, the first button  51  is pushed in the direction toward the latch tail  533 . Upon moving the first button  51  backward, the latch head  531  will be moved away from the latch cavity  15 . The plug  3  is then free to move out of the receptacle  11 . The first button  51  may be made in a desirable size and shape to make the operation simple and easy. 
     In another embodiment of the fastener (not shown in figures), the latch cavity  15  may be located in a side wall of the receptacle  11  rather than in the aforesaid rear wall shown in FIG.  1 . In such an event, the latch bar  53  and latch head  531  should also be arranged correspondingly to engage with a side latch cavity. 
     The spring strip  7  may be made of selective material and size for providing the latch bar  53  with adequate strength in engaging with the latch cavity  15 . The latch cavity  15  and the latch head  531  may be formed in any desired shape such as wedge, barrel, square, triangle and the like. 
     Due to the material property of the metal used for spring strip  7 , enough engaging force can be provided for the fastener of the present invention, and the fatigue and rupture problem in a conventional plastic-made fastener can be avoided. The first button  51  may be located at the top of the body  33  and can be arranged far away from the engaging position of the plug  3  and the socket  1 . Such an arrangement offers more flexibility in the design on the dimension and shape of the plug  3  and the socket  1 . 
     FIG. 3 illustrates another embodiment of this invention. The insert  13  has an insert body  130  that has angular recesses  133  formed symmetrically in the front, bottom and rear sides thereof. On the rear wall of the receptacle  11  and below the latch cavity  15 , there is a positioning bulge  107  which is engageable with one of the angular recesses  133  so that the insert  13  may be positioned in the socket casing  10  precisely and quickly at a desired angle. FIG. 3 also shows an embodiment variation of this invention. At opposing lateral sides of the insert body  130 , there are two spring bores  139  formed therein; bore one  139  on each lateral side. Each spring bore  139  is used to hold a spring  135  and a spring head  137 . The spring head  137  has one end forming a spindle manner which is pivotally engageable with one of two apertures  103  located in the corresponding lateral walls of the receptacle  11 . Therefore, the insert  13  may be pivotally held in the receptacle  11  by means of the spring heads  137 . The insert  13  is then able to turn about the apertures  103  from a vertical position to a horizontal position. The socket casing  10  has a pair of respective terminal slots  101  below the insert  13  to enable the lower portion of the terminals  131  be accommodated therein when the insert  13  is turned. The terminal slots  101  may have conductive contact with the lower ends of the terminals  131  and also forming conductive connection with the power cable  17 . 
     In order to make the rotation of the rotational insert  13  smooth and durable, the rear wall of the receptacle  11  may form a tongue-shaped elastic arm  105  with the positioning bulge  107  located at the free end of the arm  105 . The elastic arm  105  may be formed by cutting a U-shaped through groove in the rear wall of the socket casing  10 . The bulge  107  is thus capable of elastic engagement with one of the angular recesses  133  when the insert  13  rotates and contacts against the arm  105 . 
     Of course, in the embodiment of the recesses  133  and bulge  107 , the position of the angular recesses  133  and the positioning bulge  107  may be switched with each other and still achieve same result. That is, the bulges are formed on the locations where the recesses  133  are located and a recess is formed on the location where the bulge  107  is located. 
     FIG. 4 illustrates a further embodiment of this invention. In the receptacle  11 , there is provided with a horizontal stop bar  109  located above the insert  13 ; so that any undesirable objects may be prevented from dropping into the receptacle  11  and making contact with the insert  13 . In this embodiment, the plug body  33  should have a respective slot opening to enable the stop bar  109  to pass through during assembly. 
     FIGS. 5 and 6 show yet another embodiment of this invention for the socket  1  engaging with a conversion plug  4  capable of converting outlet of the aforesaid insert  13  to another type of outlet for connecting with a different power supply. 
     The engagement of the conversion plug  4  and the receptacle  11  is mostly like the one set forth above. However in the casing  40 , there is a conversion socket  41  that may couple with the terminals in the socket  1  to establish an electric link. The conversion socket  41  is preferably made by any standard specification such as a two-port type, three-port type, or any other type that conforms industry standards. 
     In the conversion plug  4  as shown, there is a movable second fastening member  43  that includes a second button  431  exposed outside the plug  4  and a second latch bar  433 , in which the second latch bar  433  also has a latch head engageable with the socket casing  10  and a latch tail  7  engageable with a spring like the embodiment shown in FIG.  2 . Both embodiments (i.e., those in FIGS. 2 and 6) basically provide the same function and effect already set forth above. The main difference is the size and location of the second button  431  and the first button  51 . Apparently, in the application of the present invention, the location and the size of the fastener can be various embodied, and be determined upon deciding the power supply types and design requirements. 
     It may thus be seen that the objects of the present invention set forth herein, as well as those made apparent from the foregoing description, are efficiently attained. While the preferred embodiments of the invention have been set forth for purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.