Abstract:
A tamper-resistant electrical receptacle disclosed herein includes a cover assembly having at least one pair of apertures, a cover, and at least one slider that rests in the cover behind one pair of the apertures. The slider is held in a first position where it covers both apertures such that an object is blocked from entrance in either aperture and, thereby, blocked from accessing either receptacle terminal formed in the base assembly connected to the cover assembly. This first position is maintained until prongs are substantially inserted simultaneously into the apertures causing the slider to move into a second position where the prongs are enabled to pass through the apertures, engaging the receptacle terminals. After the prongs are removed from the receptacle terminals, the slider automatically retracts to the first position. When only one aperture is probed by an object, however, the slider remains confined in the first position.

Description:
[0001]     This application claims the benefit of the filing date of a provisional application having application Ser. No. 60/715,081, which was filed on Sep. 8, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to electrical receptacles, and, more particularly, to a tamper-resistant electrical wiring device system.  
       BACKGROUND OF THE INVENTION  
       [0003]     Electrical power transmitted from a source to a point of use through an electrical distribution system within a home or a commercial building for equipment and operations is a beneficial service. Conventional electrical receptacles within such a distribution system include a pair of slots or apertures aligned with contacts, wherein prongs of an electric plug may be inserted in the pair of apertures to directly engage contacts within the receptacle in an effort to facilitate a desired electrical connection. Since a large percentage of these receptacles are used in residential buildings and are located near the floor, a young child or infant, for example, may insert a small object into either one of the apertures which potentially may result in electrical shock. More particularly, a burn or shock may result when a child&#39;s wet mouth enables electrical contact, wherein a path exists from the hot contact through the child to ground, establishing a ground fault.  
         [0004]     Besides a child&#39;s fingers and mouth, children may insert into receptacles a wide variety of objects made of conductive material including but not limited to a metal articles. Most objects may be everyday household and easily accessible items such as, paper clips, pens wire tools, hairpins, safety pins, keys, forks, knives, screws, nails, tweezers and coins. Since some of these objects may be perceived by parents as safe, parents tend not to restrict access to many of these objects.  
         [0005]     Both scenarios present circumstances to be avoided, where possible. As such, the issue of human safety and avoiding hazards has always been considered by the owner of the instant application in developing new products. Further, in an effort to eliminate the foregoing, the National Electrical Code (NEC) now requires tamper-proof electrical receptacles in pediatric environments since electrical shocks often occur in these types of environments. Research studies have shown that many of these incidents happen around meal time, when parents are occupied in the kitchen and children are not well supervised. A National Electrical Manufacturer&#39;s Association (NEMA) task force has concluded that every residential building should be required to have tamper-resistant electrical receptacles and ground fault circuit interrupters (GFCI) designed within the electrical distribution system throughout the home.  
         [0006]     Presently available circuit interrupter devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894, which is incorporated herein in its entirety by reference, use a trip mechanism to mechanically break an electrical connection between one or more input and output conductors. Such devices are resettable after they are tripped after the detection of a ground fault. The ground fault circuit interrupter, however, only disconnects the circuit after electrical contact is made with a conductor. Thus, without a tamper resistant electrical receptacle, a person may still experience an initial temporary shock.  
         [0007]     Numerous child-proof devices have been proposed or are commercially available which are directed to preventing a child from touching the apertures in a receptacle assembly or preventing a child from inserting or removing an electrical plug in or from the apertures. No such device, however, has achieved wide acceptance; therefore, the aforementioned condition remains today. This is primarily due to ineffectiveness of each device, expense, and the lack of ease of use. Foremost among these drawbacks is one of expense. That is, there are conventional devices that may be applied to various receptacles with safety features. However, the added expense required to manufacture such receptacles outweighs the safety advantage.  
         [0008]     Prior patents featuring safety electric receptacles have generally comprised attachments for the face plate of an electric receptacle featuring rotatable snap-on or sliding covers for the electric socket opening, such as disclosed by U.S. Pat. Nos. 3,639,886 and 3,656,083 in which the face plate attachments are manually moved for insertion and removal of the plug. These attachments, such as plastic receptacle caps, are generally designed to include plastic plates having a pair of wall receptacle aperture engaging blades. These plastic receptacle caps, however, are unreliable and inefficient. Research in 1997 by the Temple University Biokinetics Laboratory in Philadelphia showed that 47% of the 4 year olds in a test group were able to remove one brand of receptacle caps. For another similar embodiment of an receptacle cap, 100% of the children within the age group of 2 to 4 years of age were able to remove the receptacle cap in many cases in less than 10 seconds. Other disadvantages of plastic receptacle caps include but are not limited to the forgetfulness of adults to reinsert the caps. In addition, receptacles are susceptible to being exposed to a child who may pull a lamp cord, leaving the receptacle unprotected. Furthermore, constant pressure from the plastic blades on the receptacle contacts increase contact distortion, increasing the risk of loose contacts and/or creating poor contacts, resulting in plugs falling out of the receptacle. Moreover, many of the plastic receptacle caps may create choking hazards, since they may fail to pass a choke hazard test described in a UL standard.  
         [0009]     Other patents, such as U.S. Pat. Nos. 2,552,061 and 2,610,999 feature overlying slotted slidable plates which must be manually moved to mate the overlying plate slots with the electric receptacle slots or openings for insertion and removal of the plug. Sliding shutter plates offer a better level of protection than receptacle caps. However, none of the sliding shutter plates that are on the market are UL listed. This is primarily due to the fact that they add extra layers of material between the plug prongs and the receptacle contacts which reduces the surface of contact between plug prongs and contacts, causing potential heat rise or arcing which may also be hazardous. Another disadvantage of a manually movable face plate is that a small child, by observation, may learn to expose the electric receptacle.  
         [0010]     Thus, a need exists for an simple, effective, efficient, low-cost electrical receptacle that is tamper-proof and does not need continuous manual adjustment. This device must prevent electric shock when one inserts a conductive instrumentality other than the plug of an appliance, while still permitting full surface contact between the plug prongs and contacts and frequent insertion and removal of prongs.  
         [0011]     The present invention is directed to overcoming, or at least reducing the effects of one or more of the problems set forth above.  
       SUMMARY OF THE INVENTION  
       [0012]     To address the above-discussed deficiencies of child-proof devices for electrical receptacles, the present invention teaches a tamper resistant electrical receptacle that has a simple, effective, efficient, low-cost design that does not need continuous manual adjustment. This device prevents electric shock when one inserts an object into one aperture in the cover, while still permitting the frequent insertion and removal of plugs to an electrical appliance.  
         [0013]     Specifically, a tamper resistant electrical receptacle in accordance with the present invention includes a base assembly that connects to a cover assembly, wherein the cover assembly having at least one pair of cover apertures, includes a slider positioned in a first position to block entry into the cover assembly when an object is inserted into only one cover aperture (the typical scenario for children probing electrical receptacles). When, however, a pair of prongs are inserted into the electrical receptacle, the slider shifts out of the way into a second position that enables the pair of prongs to engage the receptacle terminals located in the base assembly. Access to the receptacle terminals is thus prevented significantly reducing the likelihood of electric shock due to contact with these terminals.  
         [0014]     A first embodiment of the tamper-resistant electrical receptacle for electrical connection between an appliance having a pair of prongs and a power distribution system includes a base assembly attached to a cover assembly. The cover assembly includes a cover having at least one pair of apertures for at least one pair of prongs of an external electrical plug to be inserted therethrough. The apertures in the cover assembly align with receptacle terminals in the base assembly. The cover assembly further includes at least one slider that rests in the cover behind one pair of the apertures. The slider is held in a first position wherein the slider covers both apertures of the cover such that an object is blocked from entering into either of the pair of apertures in the cover and, thereby, prevents access to the receptacle terminals. The slider is restricted to the first position when an object probes only one aperture in the cover. This first position is maintained until a pair of prongs are inserted into the pair of apertures causing the slider to slide into a second position allowing the pair of prongs to pass through the pair of apertures in the cover and enabling each prong to engage a respective one of the receptacle terminals. In this second position, the width of the slider is selected such that when the slider moves into this position the aperture covers are no longer covered and blocked by the slider. Thus, the receptacle terminals are fully accessible to the pair of prongs in the second position. After the pair of prongs are removed from the receptacle terminals, the slider automatically retracts to the first position where access to the receptacle terminals is blocked.  
         [0015]     Another embodiment of the tamper-resistant electrical receptacle for electrical connection between an appliance and a power distribution system includes a base assembly attached to a cover assembly, wherein the apertures in the cover assembly align with the receptacle terminals in the base assembly. The cover assembly includes a cover having at least one pair of apertures for at least one pair of prongs of an external electrical plug to be inserted therethrough. The cover assembly further includes at least one platform sub-assembly, wherein each platform sub-assembly rests in the cover behind one pair of the apertures. The platform sub-assembly includes a slider, a platform, and a leaf spring. The slider rests in the platform and is held into position by a leaf spring that is in juxtaposition with the slider.  
         [0016]     The leaf spring is used to load the slider in a first position where the slider covers both apertures in the cover such that an object is blocked from entrance into either of the pair of apertures in the cover. The leaf spring, the platform and the cover confine the slider in the first position when an object probes only one aperture in the cover. This first position is maintained until the pair of prongs are inserted into the pair of apertures causing the slider to slide into a second position allowing the pair of prongs to pass through the pair of apertures in the cover so that each prong engages a respective one of the receptacle terminals. In this second position, the slider is designed to be just wide enough to allow the receptacle prongs access to the pair of prongs. After the pair of prongs are removed from the receptacle terminals, the leaf spring automatically retracts the slider to the first position, in which access to the receptacle terminals is blocked.  
         [0017]     Another embodiment of the tamper-resistant electrical receptacle of the present invention includes a base assembly attached to a cover assembly, wherein the apertures in the cover assembly align with the receptacle terminals in the base assembly. The cover assembly includes a cover having at least one pair of apertures for at least one pair of prongs of an external electrical plug to be inserted therethrough. The cover assembly further includes at least one platform sub-assembly, wherein each platform sub-assembly rests in the cover behind one pair of the apertures. The platform sub-assembly includes a slider, a platform, and a leaf spring. The slider having a slider aperture rests in the platform and is held in position by the leaf spring that is positioned juxtaposed to the slider for loading the slider into a misaligned position where the slider aperture is misaligned with respect to the aperture in the cover such that an object is blocked from entering into either of the apertures in the cover.  
         [0018]     The leaf spring, the platform and the cover confine the slider in the misaligned position when an object probes only one aperture in the cover. This misaligned position is maintained until a pair of prongs are inserted into the pair of apertures, causing the slider to slide into an aligned position wherein the slider aperture aligns with one of the pair of apertures of the cover, thereby enabling a first prong to slip through both the cover aperture and the slider aperture, and a second prong to slip through the other cover aperture and bypassing the slider. In this alignment position, the slider is designed to be just wide enough so that the when the slider aperture aligns with one aperture in the cover, the slider does not cover the other respective aperture. Upon removal of the pair of prongs from the receptacle terminals, the leaf spring urges the slider back into the misaligned position.  
         [0019]     Another embodiment of the tamper-resistant electrical receptacle of the present invention includes a base assembly attached to a cover assembly, wherein the apertures in the cover assembly align with the receptacle terminals in the base assembly. The cover assembly includes a cover having at least one pair of apertures for at least one pair of prongs of an external electrical plug to be inserted therethrough. Moreover, the cover includes an upper rib formed on the interior surface of the cover. The cover assembly further includes at least one platform sub-assembly, wherein each platform sub-assembly rests in the cover behind one pair of the apertures. The platform sub-assembly includes a slider, a platform, and a leaf spring. The slider having a slider aperture rests in the platform and is held in position by a leaf spring that is positioned juxtaposed to the slider for loading the slider into a misaligned position where the slider aperture is misaligned with respect to the aperture in the cover such that an object is blocked from entrance into either of the pair of apertures in the cover.  
         [0020]     The platform includes a lower rib formed on its interior surface. When an object is inserted into only one first aperture of the cover, the upper rib formed on the interior surface of the cover blocks movement of the slider from transitioning from the misaligned position into an align position wherein the receptacle terminals are left open and accessible. In the alternative when an object is inserted into only one second aperture of the cover, the lower rib formed on the interior surface of the platform blocks movement of the slider from transitioning from the misaligned position into an align position wherein the receptacle terminals are left open and accessible. Thereby the upper rib of the cover and the lower rib of the platform confine the slider to the misaligned position when an object probes only one aperture in the cover. This misaligned position is maintained until the pair of prongs are inserted into the pair of apertures causing the slider to slide into an aligned position where the slider aperture aligns with one of the pair of apertures in the cover enabling a first prong to slip through both the aperture and the slider aperture, and a second prong to slip through a corresponding one of the pair of apertures bypassing the slider.  
         [0021]     In the alignment position, the slider is designed to be just wide enough so that when the slider aperture aligns with one aperture in the cover, the slider does not cover the other aperture. After the pair of prongs are removed from the receptacle terminals, the leaf spring moves the slider back into the misaligned position.  
         [0022]     Advantages of this design include but are not limited to, a tamper-resistant electrical receptacle that is permanent in that once the unit is installed it offers protection for the life of the building structure. The tamper-resistant electrical receptacle in accordance with the present invention is reliable since this receptacle is not manually removable. In addition, a user need not be concerned about losing the associated part that makes the electrical receptacle tamper-resistant. Further, a user need to be concerned with breaking the tamper-resistant electrical receptacle because the platform sub-assembly is secured behind the cover of the electrical receptacle. Moreover, the tamper-resistant electrical receptacle provides automatic protection even when a plug is removed because the spring loaded slider retracts back to the closed position for immediate protection.  
         [0023]     These and other features and advantages of the present invention will be understood upon consideration of the following detailed description of the invention and the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numbers indicate like features and wherein:  
         [0025]      FIG. 1  shows an exploded view of a 15 ampere embodiment of the tamper resistant assembly in accordance with the present invention;  
         [0026]      FIG. 2  illustrates an exploded view of a 15 ampere embodiment of the platform sub-assembly in accordance with the present invention;  
         [0027]      FIGS. 3, 7   a , and  7   b  display the platform sub-assembly completely assembled in accordance with the present invention;  
         [0028]      FIG. 4  shows the cover assembly in accordance with the present invention;  
         [0029]      FIGS. 5   a  and  5   b  display two views of the leaf spring placement by a suitable tool into the platform in accordance with the present invention;  
         [0030]      FIGS. 6   a  and  6   b  illustrate the placement of the slider into the platform, next to the leaf spring;  
         [0031]      FIG. 8  illustrates an exploded view of the base and cover assembly in accordance with the present invention;  
         [0032]      FIG. 9  displays the tamper resistant assembly in accordance with the present invention;  
         [0033]      FIGS. 10   a  and  10   b  show the tamper resistant assembly when a pair of prongs from an electrical appliance are inserted into the pair of apertures in the cover at two respective depths;  
         [0034]      FIG. 11   a  and  11   b  displays the tamper resistant assembly when a single object is used to probe apertures,  39  and  41 , in the cover, respectively;  
         [0035]      FIG. 12  displays the platform in accordance with one embodiment of the present invention;  
         [0036]      FIG. 13  shows the leaf spring in accordance with one embodiment of the present invention;  
         [0037]      FIGS. 14   a  and  14   b  illustrate the front and back side of the slider in accordance with one embodiment of the present invention;  
         [0038]      FIG. 15  shows an exploded view of the 20 ampere embodiment of the tamper resistant assembly in accordance with the present invention;  
         [0039]      FIG. 16   a  illustrates an exploded view of a 20 ampere embodiment of the platform sub-assembly in accordance with the present invention;  
         [0040]      FIGS. 16   b ,  20   a  and  20   b  display the platform sub-assembly completely assembled in accordance with the present invention;  
         [0041]      FIG. 17  shows the cover assembly in accordance with the present invention;  
         [0042]      FIGS. 18   a  and  18   b  display two views of the leaf spring placement by a suitable tool into the platform in accordance with the present invention;  
         [0043]      FIGS. 19   a  and  19   b  illustrate the placement of the slider into the platform, next to the leaf spring;  
         [0044]      FIGS. 21   a  and  21   b  show the tamper resistant assembly prior to and after the insertion of a pair of prongs from an electrical appliance into the pair of apertures in the cover;  
         [0045]      FIGS. 22   a  and  22   b  display another view of the tamper resistant assembly prior to and after the insertion of a pair of prongs from an electrical appliance into the pair of apertures in the cover;  
         [0046]      FIGS. 23   a  and  23   b  illustrate the front and back side of the leaf spring in accordance with one embodiment of the present invention;  
         [0047]      FIGS. 24   a  and  24   b  show the tamper resistant assembly when a pair of prongs from an electrical appliance are inserted into the pair of apertures in the cover at two respective depths;  
         [0048]      FIGS. 25   a  and  25   b  display the tamper resistant assembly when a single object is used to probe the apertures;  112  and  114 : in the cover, respectively;  
         [0049]      FIG. 26  illustrates an exploded view of the base and cover assembly in accordance with the present invention; and  
         [0050]      FIG. 27  displays the tamper resistant assembly in accordance with the present invention.  
         [0051]      FIGS. 28   a  and  28   b  depict a tamper resistant assembly in accordance with the present invention prior to and after insertion of a pair of prongs from an electrical appliance.  
         [0052]      FIGS. 29   a  and  29   b  depict a tamper resistant assembly in accordance with the present invention when a single object is used to probe apertures in the assembly.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0053]     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.  
         [0054]     Specifically, a tamper resistant electrical receptacle in accordance with the present invention includes a base assembly that connects to a cover assembly, wherein the cover assembly includes a platform sub-assembly having a platform, a slider, and a leaf spring. The slider positioned is placed in a first position to block entry into the cover assembly when an object is inserted into only one cover aperture which is the typical scenario for children probing electrical receptacles. When, however, a pair of prongs are inserted into the electrical receptacle, the slider shifts out of the way into a second position that enables the pair of prongs to engage receptacle terminals located in the base assembly. Thereby, this electrical receptacle effectively prevents electric shock  
         [0055]      FIGS. 1-14   b  illustrate a first embodiment of the tamper resistant receptacle  40  in accordance with the present invention. Specifically,  FIG. 1  shows an exploded view of the tamper resistant electrical receptacle  40  in accordance with the present invention. The receptacle  40 , as shown in  FIG. 1 , is a duplex three-prong electrical receptacle for handling 15 amp current applications. However, it should be understood that the receptacle can be a two or three-prong electrical receptacle or a receptacle other than that of a duplex receptacle.  
         [0056]     As shown in  FIG. 1 , cover  20  sits on top of a pair of platform sub-assemblies including platform  16 , leaf spring  14  and slider  12 . Mounting screws  46  mount strap  48  onto the base  56  using retaining washers  50 . Ground contacts  42  connect onto strap  48 . Finally, contacts  52  connect to the base  56  using terminal screws  54  to form the receptacle terminals in base  56 .  
         [0057]     Specifically, referring to  FIG. 2 , an exploded view of the platform sub-assembly includes a slider  12 , a leaf spring  14 , and a platform  16 . Slider  12  includes at least one rib  13 . It is noted that rib  13  may be one or more projections as shown in  FIGS. 2 and 14   b . A slider aperture  15  is included in slider  12  to enable one prong to be inserted through to make contact with the receptacle terminals in the base of the tamper resistant receptacle  40 . The cover  20  may include at least one pair of apertures. As such, slider aperture  15  must align with at least one of the apertures from an aperture pair of cover  20  to enable a prong to pass through the slider aperture  15  to a receptacle terminal which shall be explained in further detail.  
         [0058]     Leaf spring  14  is mounted in pocket  17  of platform  16  as is shown in the series of  FIGS. 5   a ,  5   b ,  6   a ,  6   b ,  7   a , and  7   b . Accordingly, pocket  17  is configured to allow leaf spring  14  to rest in platform  16  and to hold slider  12  in place in a first position wherein the slider aperture  15  is misaligned with either aperture  11  of the platform  16 . Specifically, leaf spring  14  is driven into pocket  17  using an appropriate tool  18  as shown in  FIG. 5   a .  FIG. 5   b  displays the top view of the insertion of the leaf spring  14  into the platform using the tool  18 . It should be noted that leaf spring  14  can be manually or mechanically placed into the platform sub-assembly. Likewise slider  12  is inserted either manually or mechanically as is shown in  FIGS. 6   a  and  6   b .  FIGS. 3, 7   a , and  7   b  show the completed platform sub-assembly from differing views, including isometric and top views.  
         [0059]     Referring to  FIG. 4 , the fully assembled cover assembly  30  includes at least one platform assembly  10  seated in the cover  20  behind the pair of apertures  29 . In one embodiment the cover  20  and the platform sub-assembly  10  are held together by interference fit.  
         [0060]      FIG. 8  displays cover assembly  30  aligned with the base assembly  36  to be combined to make tamper-resistant receptacle  40  shown in  FIG. 9 . Base assembly  36  includes all elements associated with a known electrical receptacle (i.e. strap, contacts, etc). The fully assembled tamper resistant receptacle  40  in accordance with the present invention is shown in  FIG. 9 . As shown, the outside of the 15 A, (125V) version of the tamper resistant receptacle in accordance with the present invention looks the same as an existing Leviton receptacle with the exception of the tamper-proof prong apertures. Accordingly, receptacle  40  offers the same features relative to the mounting strap.  
         [0061]     The receptacle  40 , shown in  FIG. 10 , is shown as a duplex three-prong electrical receptacle for handling 15 amp current applications. However, it should be understood that the receptacle can be a single two or three-prong electrical receptacle or a receptacle having capabilities greater than that of a duplex receptacle. In addition, the receptacle can have ground fault circuit interrupter (GFCI) capabilities. Moreover, the receptacle can be selected to handle other current capacities such as 20 amp, 30 amp, and 50 amp and other capacities.  
         [0062]     For another perspective,  FIG. 12  provides a top view of platform  16 . Furthermore,  FIG. 13  provides a more detailed view of leaf spring  14 . Moreover,  FIGS. 14   a  and  14   b  displays front and back views of slider  12  for a more direct view of the ribs  13  formed on the back side of slider  12 .  
         [0063]      FIGS. 10   a  and  10   b , illustrate what happens when an electrical plug having a pair of prongs is inserted in the apertures of the cover  20 . As shown in  FIG. 10   a , just prior to having a pair of prongs inserted through the apertures in cover  20 , the slider  12  blocks direct entry into the receptacle terminals formed by contacts  37 . This first position for slider  12  is referred to as a misaligned position. As prongs  19  are inserted further, projection  25  of slider  12  slides into a second position down the slope  27  such that slider aperture  15  comes into alignment with one of the prongs  19 .  FIG. 10   b  illustrates the slider in an intermediary position, mid-way between the first position and the second position. This second position is referred to as an alignment position. As shown in  FIG. 10   b , projection  25  slides down slope  27  which brings slider aperture  15  closer in alignment with one of prongs  19 . Once the slider  12  transitions completely to the second position, slider  12  aligns with the cover apertures,  39  and  41 , to allow a first prong of prongs  19  to bypass on side of slider  12  and a second prong of prongs  19  to pass through slider aperture  15 . As such, the width of the slider  12  is designed such that the other prong gains clearance straight through to the receptacle terminal when slider aperture  15  aligns with the aperture in cover  20 . Thus, for this particular embodiment, the width between the slider aperture  15  and far end of the slider  12  should substantially equal the width that exists between the apertures in the cover  20 . The first and second prongs  19  engage with receptacle terminals  37  to complete electrical contact with 40 once slider  12  has transitioned completely to the second position.  
         [0064]     As shown in  FIG. 6   a , leaf spring  14  rests in pocket  17  juxtaposed to slider  12  in the first position. When the slider  12  transitions to the second position, the slider moves toward the pocket  17  and the leaf spring  14 . As a result, the leaf spring  14  is compressed to the edge of the platform  16 . Leaf spring  14  is designed to retract to its original position after being compressed similar to a conventional spring. Thus, when the prongs  19  are withdrawn, the leaf spring  14  springs slider  12  back to the first position.  
         [0065]      FIGS. 11   a  and  11   b , display what happens when a simple straight insertion is attempted only through either the cover aperture,  41  or  39 , respectively. In this case, when an object is inserted into either aperture  39  or  41 , slider  12  remains confined in the misaligned position or the first position. Specifically,  FIG. 11   a  illustrates an object  22  being inserted in the aperture  41  of cover  20 . As object  22  pushes slider  12  down towards the platform  16 , the lower rib or projection  23  restricts the movement of the slider  12 , such that slider  12  just tilts as oppose moving into the second position. Thereby, object  22  is prohibited from making contact with contacts  37  which form each receptacle terminal. In the alternative,  FIG. 11   b  displays an object  22  inserted in the aperture  39  of cover  20 . As shown, slider  12  is pushed downward towards platform  16  and is restricted from further movement down the slope  27  due to projection  21  formed in the cover  20 . Similarly, as a result, slider  12  is disabled from transitioning to the second position. Thus, object  22  which probes the electrical receptacle  40  unsuccessfully makes contact with the accessible power of contacts  37  which form the receptacle terminal.  
         [0066]     It should be noted that while most tamper resistant receptacles require a sloped surface to be engaged by the plug prong in order to obtain a lateral move, this mechanism incorporates a flat surface (i.e. the top surface of slider  12 ) instead for the prongs to push on in combination with a sloped surface in the interior surface of the platform  16  that causes the slider to move sideways as it is being pushed by prongs  19 .  
         [0067]      FIGS. 15-27  depict the component assemblies for a second embodiment of the tamper-resistant receptacle  300  in accordance with the present invention. The receptacle  300 , as shown in  FIG. 15 , is a duplex three-prong electrical receptacle for handling 20 amp current applications. However, it should be understood that the receptacle can be a single two or three-prong electrical receptacle or a receptacle other than that of a duplex receptacle. In addition, the receptacle can have ground fault circuit interrupter (GFCI) capabilities. The receptacle also can be selected to handle other current capacities such as 30 amp, 50 amp, and other capacities.  
         [0068]      FIG. 15  shows an exploded view of the 20 ampere embodiment of the tamper resistant electrical receptacle in accordance with the present invention. From the top of  FIG. 15 , cover  150  sits on top of platform sub-assembly  100  including platform  106 , leaf spring  104  and slider  102 . Terminal screws  256  connect the contacts  254  and wire nut  252  together within base  258 . Screws  260  mounts strap  262  onto the base  258  using washers  264 . Ground screw  268  secures ground clamp  266  and ground clip  270  to strap  262 .  
         [0069]     In particular, and focusing upon the platform sub-assembly  100 ,  FIG. 16   a  illustrates an exploded view of the platform sub-assembly  100  which includes a slider  102 , a leaf spring  104 , and a platform  106 . Slider  102  includes at least one rib  120  displayed in  FIGS. 22   a ,  22   b ,  24   a  and  24   b . Similar to the previously described embodiment  40 , it is noted that rib  120  may be one or more than one projections (not shown). Slider  102  includes a slider aperture  110  for alignment with the aperture of cover  150  which is explained in detail hereinafter. Leaf spring  104  is mounted in the pocket  107  of platform  106  as is shown in the series of  FIGS. 18   a ,  18   b ,  19   a ,  19   b ,  20   a , and  20   b .  FIGS. 23   a  and  23   b , front and back views of leaf spring  104 .  
         [0070]     Accordingly, leaf spring  104  rests in the pocket  107  of platform  106  to bias slider  102  in place in a first position where the slider aperture  110  is misaligned with either aperture  111  of the platform  106 . Specifically, leaf spring  104  is driven into pocket  107  using an appropriate tool  108  as shown in  FIG. 18   a .  FIG. 18   b  displays the top view of the insertion of the leaf spring  104  into the platform using the tool  108 . Although  FIG. 18   a  refers to the platform assembly being manually assembled, it should be recognized by those skilled in the art that leaf spring  104  may be manually or mechanically inserted.  FIGS. 19   a  and  19   b  show the platform sub-assembly being assembled by hand, wherein the slider is pushed into the slot within the platform juxtaposed to the leaf spring which holds the slider in place. The fully assembled sub-assembly  100  is shown in  FIGS. 16   b ,  20   a , and  20   b  includes the platform  106 , leaf spring  104 , and slider  102 . These are placed in the cover assembly  200  as shown in  FIG. 17 .  
         [0071]     Referring to  FIG. 17 , the fully assembled cover assembly  200  includes at least one platform assembly  100  seated in the cover  150  behind the pair of apertures  152 . In one embodiment the cover  150  and the platform sub-assembly  100  are held together by interference fit. The resulting cover assembly  200  is attached to the base assembly  250  as shown in  FIGS. 26 and 27  to form the tamper resistant electrical receptacle  300 . Specifically,  FIG. 26  displays cover assembly  200  aligned with the base assembly  250  to be combined to make tamper-resistant receptacle  300 . Base assembly  250  includes all elements associated with a known electrical receptacle (i.e. strap, contacts, etc). The fully assembled tamper resistant receptacle  300  in accordance with the present invention is shown in  FIG. 27 . The outside of the 20 A, (125V) version of the tamper resistant receptacle in accordance with the present invention looks the same as an existing Leviton receptacle with the exception of the tapered blade slots. The tamper-resistant receptacle offers the same features of the known receptacle including but not limited to those associated with the wrap around mounting strap. The marking on the face of the tamper-resistant receptacle helps to identify and distinguish it from the known electrical receptacle.  
         [0072]     In operation, slider  102  is initially in a first position where the slider blocks each aperture,  112  and  114 , in the cover  150  as shown in  FIGS. 21   a  and  22   a . As shown, leaf spring  104  engages the slider  102  in the first position wherein the slider aperture  110  is misaligned with the aperture,  112  or  114 , in the cover  150 . As shown in  FIG. 24   a , rib  120  of slider  102  comes in contact with the cavity  118  of platform  106  allowing the slider  102  to move laterally. Leaf spring  104  biases slider  102  and retains the slider  102  to one side in a position where the slider aperture  110  is misaligned with either aperture,  112  or  114 , in the cover  150 . Similar to the previous embodiment as shown in  FIG. 14   b , it is noted that rib  120  may be more than one rib on the bottom slider  102 .  
         [0073]     Further, as shown in  FIG. 24   a  when a conventional electrical plug having a pair of prongs are inserted into the cover  150  of receptacle  300  through the apertures in cover  150 , the slider blocks entry into the receptacle terminals formed by contacts  117 . As the prongs  116  are inserted further, the projection  120  of slider  102  slides into a second position down into cavity  118  such that slider aperture  110  comes into alignment with one of the prongs  116 .  FIG. 24   b  illustrates the slider  102  in an intermediary position, mid-way between the first position and the second position. As shown in  FIG. 24   b , projection  120  slides down into chamber  118  which brings slider aperture  110  closer in alignment with one prong  116 . Once the slider  102  transitions completely to the second position, slider  102  aligns with the cover apertures,  112  and  114 , to allow a first prong of prongs  116  to bypass on side of slider  102  and a second prong of prongs  116  to pass through slider aperture  110 . As such, the width of the slider  102  is designed such that the other prong gains clearance straight through to the receptacle terminal when slider aperture  110  aligns with the aperture in cover  150 . When the slider  102  is in the alignment position, the prongs are allowed to enter through cover assembly  200  so as to engage the contacts  117  that form the receptacle terminals for the receptacle  300 .  FIGS. 21   b  and  22   b , illustrate the alignment position wherein the slider  102  has shifted into the second position providing clearance for both apertures,  112  and  114 , in cover  150 . In this position, slider  102  presses against the leaf spring  104  and is held in the alignment position by the prongs  116  which are inserted therein. When the prongs  116  are removed, the biasing force of the leaf spring  104  urges slider  102  back into the misaligned position as shown in  FIGS. 21   a  and  22   a .  FIGS. 22   a  and  22   b , depict the slider  102  in the first and second positions similar to  FIGS. 21   a  and  21   b , but from a different angle.  
         [0074]     Specifically,  FIGS. 24   a  and  24   b , differ from  FIGS. 25   a  and  25   b , in that the viewing prospective of the diagram for  FIGS. 24   a  and  24   b , shows a cross-section view of  FIG. 27  taken along Section line A-A where the cut extends through receptacle  300  at the point through either rib  120 .  FIGS. 25   a  and  25   b , show a cross-section view of  FIG. 27  taken along Section line B-B which represents a cut through the space that lies between ribs  120 . Thus, rib  120  is not shown in  FIGS. 25   a  and  25   b  since the cut is in the section between the two part rib  120  (reference  FIG. 14   b ).  
         [0075]     In the case where an object is inserted into either aperture, the slider  102  remains confined in the misaligned position or the first position.  FIGS. 25   a  and  25   b , display what happens when an insertion is attempted in either aperture  112  and  114 , respectively. As depicted in  FIG. 25   a  when an object  126  is inserted in the aperture  114  of cover  150 , slider  102  is pushed down towards the platform and is confined by a lower rib or projection  122 . Thus, even if a determined attempt is made to force slider  102  in the aperture  114  of the cover  150 , projection  122  blocks the slider  102  from movement out of the first position where the slider aperture  110  is misaligned with the aperture in the cover  150 . Object  126  is thereby prohibited from making contact with the contacts  117  that form the receptacle terminal.  
         [0076]      FIG. 25   b  depicts an object  126  being inserted in aperture  112  of cover  150 . As depicted therein, slider  102  pushes downward towards the platform  106  and only limited movement is permitted before the right edge (as shown) of slider  102  is blocked from further movement by projection or rib  124 . Thus, projection  124  blocks slider  102  from movement out of the first position, wherein slider aperture  110  is misaligned with the aperture in the cover  150 .  
         [0077]     Note that while most tamper resistant concepts require a sloped surface to be engaged by the plug blade in order to obtain a lateral move, the tamper resistant electrical receptacle  100  in accordance with the present invention includes a flat surfaced slider  102  for the blades to push on. A sloped surface  120  in the interior surface of the slider  102  causes the slider  102  to move laterally into cavity  118  defined by platform  106 .  
         [0078]      FIGS. 28 and 29  discloses another embodiment of the present invention comprising a shutter having a different geometry than those of the embodiments previously described herein. As is depicted in  FIG. 28   a , a receptacle  300  in accordance with this embodiment comprises a shutter  301  shaped such that a locking end  304  is adapted to nestle in pocket  302 , engage tab  308  or slide down ramp  309  depending on the type of force applied to the shutter. As shown in  FIG. 28   a , when prongs  305  and  306  are inserted into apertures  310  and  311  respectively an evenly distributed force is placed on shutter  301  thereby causing shutter  301  move from a first position as shown in  FIG. 28A , to a second position as shown in  FIG. 28   b.    
         [0079]     With a balanced force applied to the shutter  301 , the shutter  301  slides down ramp  309  thereby permitting prong  305  to slide past locking end  304  and allowing prong  306  to penetrate shutter aperture  312 . This condition is depicted in  FIG. 28   b . In the instance where a projection is placed in only one of the apertures of the receptacle  300 , the shutter  301  is thereby subjected to an unbalanced force and prevented from translating along ramp  309  by locking end  304 . This condition is depicted in  FIGS. 29   a  and  29   b .  FIG. 29   a  depicts the resulting condition when a projections placed in the left aperture of receptacle  300 . When this occurs, shutter  301  is caused to pivot such that locking end  304  engages tab  308 , thereby preventing any translation of shutter  301  from its initial position.  FIG. 29   b  depicts the case where a single projection is placed in the right aperture of receptacle  300 . When this occurs, shutter  301  is again caused to pivot. However in this instance locking end  304  is made to fully nestle in pocket  302 , thereby causing locking end  304  to engage the body of the receptacle  300  and preventing translation of shutter  301 . This embodiment permits the shutter  301  to translate a distance greater than that afforded by the other embodiments of the invention. In this embodiment the preferred distance is  0 . 375 ″ whereas in the prior embodiments the preferred distance is  0 . 125 ″ 
         [0080]     Those of skill in the art will recognize that the physical location of the elements illustrated in  FIGS. 1 and 15  can be moved or relocated while retaining the function described above. For example, the location and shape of the leaf spring may be adjusted or reversed and the function of the tamper resistant assembly in accordance with the present invention will remain.  
         [0081]     Advantages of this design include but are not limited to a tamper-resistant electrical wiring device system having a high performance, simple, and cost effective design.  
         [0082]     The reader&#39;s attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.  
         [0083]     All the features disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.  
         [0084]     The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.