Abstract:
A lockable connector includes a receptacle having an opening located on an engagement surface and a spring clip slidably attached to the receptacle, the spring clip having a plug retention tang oriented substantially perpendicular to the opening on the engagement surface, the plug retention tang being positioned on the spring clip so that when the spring clip assumes a locking position the plug retention tang aligns with the opening located on the engagement surface of the receptacle.

Description:
BACKGROUND 
     Connections using the Universal Serial Bus (USB) standard are becoming increasingly more commonplace and useful in computer peripheral devices, audiovisual equipment, and electronic devices in general. Such devices have advantages including a simple mechanical connection, an ability to connect and disconnect while a device is in operation (“hot plugging”), an ability to connect several devices, and a large selection of devices using this connection standard. 
       FIG. 1  shows an existing standard type A USB plug and receptacle. The USB receptacle  12  contains a metallic connector casing  14  having upper  16  and lower  18  surfaces, each surface having a pair of plug retention prongs  20  typically cut and formed out of the resilient metal used to manufacture the metallic connector casing  14 . The plug retention prongs  20  each have a detent  22  for engaging and holding a USB plug  10 . The plug retention prongs  20  on the upper surface  16  are biased downwardly toward the lower surface  18  and the plug retention prongs  20  on the lower surface  18  are biased upwardly toward the upper surface  18 . 
     The USB plug  10  has a metallic connector body  24  connected to a cable  26  for communication with a device. The connector body  24  has an upper surface  28  and a lower surface  30 . Each of the upper and lower surfaces  28  and  30  has a pair of features configured to receive the detent portion  22  of a corresponding plug retention prong  20 . An example of such features are typically square surface holes  32 , which are aligned with and receive the detents  22  of the plug retention prongs  20  of the USB receptacle  12  when the USB plug  10  is fully inserted into the receptacle  12 . 
     As the USB plug  10  is inserted into the USB receptacle  12 , the upper and lower plug retention prongs  20  are forced outwardly from an inner resting position to an outwardly flexed position. When the USB plug  10  is inserted to the point where the retention prongs  20  align with the surface holes  32 , the plug retention prongs  20 , being made of resilient material, naturally return inwardly toward an inner holding position and the detents  22  at least partially fall into the holes  32 , creating a releasable snap fit which retains the USB plug  10  in the receptacle  12 . Because the detents  22  of the plug retention prongs  20  are somewhat rounded, such a connection allows relatively easy insertion and removal of the USB plug  10  from the USB receptacle  12 , while providing at least some resistance to disconnection. 
     Unfortunately, such ease of connection and disconnection creates a problem for use with certain devices where a more secure attachment is desired. In such devices, a user may wish to connect the USB device only once, and not disconnect the device unless the device is to be removed or replaced by authorized personnel. For these devices it is desired that the device remain securely attached even when subject to extreme unauthorized removal forces, and any removal means be accessible only to authorized personnel. 
     SUMMARY 
     Embodiments of a lockable connector include a receptacle having an opening located on an engagement surface and a spring clip slidably attached to the receptacle, the spring clip having a plug retention tang oriented substantially perpendicular to the opening on the engagement surface, the plug retention tang being positioned on the spring clip so that when the spring clip assumes a locking position the plug retention tang aligns with the opening located on the engagement surface of the receptacle. 
     Other embodiments are also provided. Other systems, methods, features, and advantages of the invention will be or become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention can be better understood with reference to the following figures. The components within the figures are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. 
         FIG. 1  shows an existing USB plug and receptacle. 
         FIG. 2  is a schematic diagram illustrating an embodiment of a USB receptacle having positive retention. 
         FIG. 3  is a schematic diagram illustrating a USB receptacle assembly adapted to house the modified USB receptacle of  FIG. 2 . 
         FIG. 4  is a schematic diagram illustrating an exploded view of the USB receptacle assembly of  FIG. 3 . 
         FIG. 5  is a schematic diagram illustrating the attachment of a USB plug to the USB receptacle of  FIG. 2 . 
         FIG. 6  is a schematic diagram illustrating the spring clip and plug retention tang of  FIG. 2 . 
         FIG. 7  is a schematic diagram illustrating the modified USB receptacle and USB plug coupled together. 
         FIG. 8  is a flow chart describing the operation of an embodiment of a method for using a USB receptacle having a positive retention feature. 
     
    
    
     DETAILED DESCRIPTION 
     Although described with particular reference to a specific USB connector defined by the USB specification for series A (also referred to as type A or standard type A) plugs and receptacles, embodiments of the positive retention feature of the USB connector described herein can be used with similar form factor connectors. 
       FIG. 2  is a schematic diagram  200  illustrating an embodiment of a USB receptacle having a positive retention feature. A modified USB receptacle  201  includes an opening  202  formed in an engagement surface  203  of the modified USB receptacle  201 . The opening  202  can be formed by removing any of the plug retention prongs  20  of a standard USB receptacle, or a modified USB receptacle  201  can be initially formed to include at least one opening  202  on any surface. Although the opening  202  is illustrated as having a shape similar to a shape of an opening having a plug retention prong  20 , the opening  202  can have other shapes. Further, the engagement surface  203  can be on either side of the modified USB receptacle  201  that includes the opening  202 . 
     A spring clip  204  is associated with the modified receptacle  201  so that a plug retention tang  206  located on the spring clip  204  aligns with the opening  202 . The opening  202  can be any shape adapted to receive the plug retention tang  206 . The major axis  232  of the plug retention tang  206  located on the spring clip  204  is oriented generally perpendicular to the major axis of the plug retention prong  20  ( FIG. 1 ) and generally perpendicular to the major axis  234  of the opening  202 . This orientation facilitates the installation of the spring clip  204  over the modified receptacle  201  by allowing the plug retention tang  206  and the spring clip  204  to slide over the engagement surface  203  of the modified receptacle  201  until the plug retention tang  206  drops into the opening  202  and into a corresponding opening (e.g.,  32  in  FIG. 1 ) in a mating USB plug  10  ( FIG. 1 ) that is inserted into the modified USB receptacle  201 . Due to its orientation, the plug retention tang  206  will not move upward when a USB plug  10  ( FIG. 1 ) is pulled from the modified receptacle  201  as the plug retention tang  206  presents an immovable edge  216  to a corresponding edge of the square opening  32  in the USB plug  10 . 
       FIG. 3  is a schematic diagram illustrating a USB receptacle assembly  300  adapted to house the modified USB receptacle  201  of  FIG. 2 .  FIG. 4  is a schematic diagram illustrating an exploded view of the USB receptacle assembly of  FIG. 3 .  FIG. 5  is a schematic diagram illustrating the attachment of a USB plug to the USB receptacle of  FIG. 2 . 
     Referring to  FIGS. 2 ,  3 ,  4  and  5 , the spring clip  204  is attached to the modified receptacle  201  so that the plug retention tang  206  rests on the engagement surface  203 , but is not yet engaged in the opening  202 . To retain the spring clip  204  in place on the modified receptacle  201  and to prevent unauthorized access to the spring clip  204 , a two-piece case  301 , having an upper portion  308  and a lower portion  310  is attached around the modified receptacle  201  and the spring clip  204  using attachment screws  402 , or any other suitable attachment means, such as, for example, adhesive, rivets, or any other attachment means. Once the USB receptacle assembly  300  is assembled together, a USB plug  502  can be inserted into the modified receptacle  201  in the direction shown by arrow  512  ( FIG. 5 ) so that the opening  532  in the USB plug  502  aligns with and falls within a periphery of the opening  202  in the modified USB receptacle  201 . After the USB plug  502  is fully inserted into the modified USB receptacle  201 , to lock the USB plug  502  to the modified USB receptacle  201 , a tool such as a small screwdriver or other similar tool can be inserted into the hole  316  in the case  301  and can be used to push the spring clip  204  in the direction indicated by arrow  514  so that the spring clip  204  slides across the engagement surface  203 . As the spring clip  204  slides across the engagement surface  203  and reaches the opening  202 , the plug retention tang  206  falls into the opening  202  and engages the opening  532  in the USB plug  502 . Further, the edge  222  of the spring clip  206  can be adjacent to an edge  224  of a lip  226  formed as part of the modified USB receptacle  201 . Thus, when so connected with the plug retention tang  206  engaged in the opening  202  and in the opening  532 , force exerted when attempting to withdraw the USB plug  502  from the modified USB receptacle  201  will be resisted when the edge  216  of the plug retention tang  206  meets and engages the edge  518  of the opening  532 , thus creating positive retention between the modified USB receptacle  201  and the USB plug  502 . 
     In order to remove the USB plug  502  from the modified USB receptacle  201 , the spring clip  204  is moved back to its initial unlocked position by inserting a tool, such as a small screwdriver or other similar tool into the opening  318  in the case  301 , engaging the lip  207  of the spring clip  204 , and then moving the spring clip  204  back to its initial position in the direction opposite that of arrow  514 , to the unlocked position. 
       FIG. 6  is a schematic diagram illustrating the spring clip and plug retention tang of  FIG. 2 . The detail  610  shows an embodiment of the plug retention tang  206  having a depth of approximately 0.035″ and a length of approximately 0.079″. An example width is 0.040″, but the width can be any width so long as the plug retention tang  206  engages the opening  532 , as described herein. The dimensions shown herein are for example purposes only. 
       FIG. 7  is a schematic diagram illustrating the modified USB receptacle  201  and USB plug  502  coupled together. When the modified USB receptacle  201  and USB plug  502  are coupled together, the opening  532  in the USB plug  502  aligns within the periphery of the opening  202  in the modified USB receptacle  201 . When the spring clip  204  is moved in the direction indicated by arrow  514  ( FIG. 5 ), the plug retention tang  206  falls into the opening  202  and engages the opening  532 . Force exerted when attempting to withdraw the USB plug  502  from the modified USB receptacle  201  is resisted when the edge  216  of the plug retention tang  206  meets and engages the edge  518  of the opening  532 . This engagement creates positive retention between the modified USB receptacle  201  and the USB plug  502 . 
       FIG. 8  is a flow chart describing the operation of an embodiment of a method for using a USB receptacle having a positive retention feature. The steps in the flow chart  800  can be performed in or out of the order shown, and in some instances, may be performed in parallel. 
     In block  802 , a USB receptacle is provided to include an opening configured to receive a plug retention tang. 
     In block  804 , the modified USB receptacle is provided with a spring clip having the plug retention tang. 
     In block  806 , a USB plug is mated to the modified USB receptacle. 
     In block  808 , the spring clip is caused to slide across an engagement surface of the modified USB receptacle such that the plug retention tang engages the opening in the modified USB receptacle and an opening in the USB plug. 
     While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of this invention.