Abstract:
An electrical socket safety device is disclosed which comprises a base plate for an electrical receptacle exposing multiple electrical sockets thereon, a sliding plate slidably engaging the base plate for covering the electrical sockets, a spring urged to protrude through a slot in the base plate, a concave space on the sliding plate for accommodating the protruding spring, the concave space forcing a first slope on the spring to depress the same into the slot when the sliding plate sliding in one direction, the concave space forcing a second slope of the spring to depress the same into the slot when the sliding plate sliding in an opposite direction, wherein the engagement of the concave space and the spring holds the sliding plate in a predetermined position, and the disengagement of the concave space and the spring requires a predetermined amount of force.

Description:
BACKGROUND 
   The present invention relates generally to electrical sockets, and, more particularly, to electrical sockets with safety covers. 
   Electrical sockets for supplying electrical power to electrical equipments are common fixtures in homes and other buildings. Electrical sockets of conventional electrical receptacles are exposed, that poses a child safety hazard, as curiosity may induce a child to insert objects into openings of the electrical sockets, and get injured or even be killed. 
   Because of this safety hazard, many devices to limit children&#39;s access to the receptacles have been designed and marketed. For example, plastic safety plugs with prongs that fit snugly into the openings of an electrical socket are readily available on the market. But it is not convenient to always have to unplug and plug such a plastic safety plug when one needs to use an electrical socket. 
   Other safety devices for electrical outlets are known in the art. For example, U.S. Pat. No. 7,094,969 issued to In provides a base plate with a top panel, on which a spring loaded locking means is devised. A sliding cover plate joins the top panel and is locked by the spring loaded locking means when the sliding cover plate is in the closed position to limit access to the electrical outlet. Although this device offers secured covering of the electrical outlets, it may not be very cost effective as a top panel on the base plate is added. 
   U.S. Pat. No. 6,342,676 issued to Ha teaches a safety guard device for an electrical socket which comprises a base plate and a sliding cover plate. The sliding cover plate contains an aperture which is positioned to provide selective registry with at least one aperture in the base plate and thus access to the electrical receptacle. Such aperture on the sliding cover plate requires a complicated alignment mechanism between the base plate and the sliding cover plate and also makes the cover plate less ornamental. 
   As such, what is desired is an electrical socket safety cover that is secure and easy to operate, as well as makes the electrical socket less conspicuous. 
   SUMMARY 
   This invention discloses an electrical socket safety device which comprises a base plate for an electrical receptacle exposing multiple electrical sockets thereon, a sliding plate slidably engaging the base plate for covering the electrical sockets, a spring urged to protrude through a slot in the base plate, a concave space on the sliding plate for accommodating the protruding spring, the concave space forcing a first slope on the spring to depress the same into the slot when the sliding plate sliding in one direction, the concave space forcing a second slope of the spring to depress the same into the slot when the sliding plate sliding in an opposite direction, wherein the engagement of the concave space and the spring holds the sliding plate in a predetermined position, and the disengagement of the concave space and the spring requires a predetermined amount of force. 
   The construction and method of operation of the invention, however, together with additional objectives and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of an electrical socket safety device according to one embodiment of the present invention. 
       FIG. 2  is a side view from the bottom of the electrical socket safety device. 
       FIG. 3  is a cross-sectional view of the electrical socket safety device. 
       FIG. 4  is close-up prospective view of a retention spring on the side of the electrical socket base plate. 
       FIGS. 5A and 5B  are cross-sectional views illustrating the retention spring engaging the sliding cover. 
   

   DESCRIPTION 
   The present invention discloses an electrical socket safety device that includes a sliding cover for covering the electrical socket when it is not being used. The sliding cover is retained in place by one or more retention springs, and can easily slide up and down by a school age or older person but not by a small child. Because the sliding cover has a smooth surface, when covering the electrical socket, it also provides an ornamental utility to the electrical socket. 
     FIG. 1  is a perspective view of an electrical socket safety device  100  according to one embodiment of the present invention. The electrical socket safety device  100  has a sliding cover  110 , slidably engaging an electrical socket base plate  120 . Since a standard electrical receptacle has two sockets, the base plate  120  has two apertures  122  for exposing the two electrical sockets  124 , respectively. The surface of the base plate  120  is approximately flush with surfaces of the electrical sockets  124 . Each vertical side of the sliding cover  110  has an internally facing groove  112  that is designed to fit over a vertical edge  126  of the base plate  120 , so that the sliding cover  110  can slide up and down the base plate  120  with the guidance of the groove  112  and the vertical edge  126 . In this case the sliding cover  110  is wider than the base place  120 . 
   Referring again to  FIG. 1 , there are two protruding retention springs  130  on each vertical edge  126  of the base plate  120 . The retention springs  130  fit into concave spaces (not shown in  FIG. 1 ) on the groove  112 . When a retention spring  130  fits into a concave space, with the urge of the spring force from the retention spring  130 , the sliding cover  110  is held in a predetermined position. The spring force is strong enough that a small child cannot slide the sliding cover  110 , but weak enough for an older kid, and of course an adult to slide the sliding cover  110 . A small child is generally regarded as a pre-school age kid, who may not comprehend the danger of electricity, and they are primarily the people the safety device of the present invention is intended to protect. The retention springs  130  and the concave spaces are so placed, the sliding cover  110  can be retained either covering both the electrical sockets  124  or covering only one of the electrical sockets  124 . 
   Although the sliding cover  110  having the grooves  112  is described, one having skills in the art would recognize that the base plate  120  may instead have internally facing grooves that may fit vertical edges of a sliding cover. In this case the sliding cover is narrower than the base plate. 
     FIG. 2  is a side view from the bottom of the electrical socket safety device  100  of  FIG. 1 . The electrical socket safety device  100  has symmetrical sides. An edge  126  of the base plate  120  fits in a groove  112  of the sliding cover  110 . The base plate  120  with a predetermined thickness is mounted against a wall  220 , so that the groove  112  of the sliding cover  110  does not contact the wall  220  for easy sliding. 
     FIG. 3  is a cross-sectional view of the electrical socket safety device  100 . The cross-section is taken at the A-A′ plane as shown in  FIG. 2 . The electrical socket safety device  100  is conventionally made symmetrical. The retention springs  130  protrude from the edges  126  of the base plate  120 . Corresponding concave spaces  312  on the grooves  126  receive the protruding retention springs  130 , respectively. The combination of the protruding retention springs  130  and the concave spaces  312  serves to hold the sliding cover  110  in predetermined vertical locations. As shown in  FIG. 3 , when the sliding cover  110  which is represented by the grooves  112  covers both electrical socket apertures  122 , all the retention springs  130  and the concave spaces  312  are engaged. When the sliding cover  110  slides upward exposing the bottom electrical socket aperture  122 , only the lower pair of the concave spaces  312  engage the upper pair of the protruding retention springs  130 . The sliding cover  110  can slide all the way out of the base plate  120 , and then both the electrical socket apertures  122  are exposed. 
     FIG. 4  is close-up prospective view of a protruding retention spring  130  on the edge  126  of the electrical socket base plate  120 . There is a slot  425  on the edge  126  of the base plate  120 . The retention spring  130  protrudes from the slot  425  at the urge of the spring force, and can be pushed back into the slot  425  (not shown in  FIG. 4 ). 
     FIGS. 5A and 5B  are cross-sectional views illustrating the retention spring  130  engaging and disengaging, respectively, the concave space  312  on the groove  112  of the sliding cover  110 . Referring to  FIG. 5A , the retention spring  130  is a wire or plate spring that is permanently bent into a “V” shape with a straight portion extended from each tip of the “V”. Slopes  130 A and  130 B of the V-shaped retention spring  130  are preferably symmetrical because the sliding cover needs to slide in both up and down directions. The upper and lower ends of the retention spring  130  are fastened to the base plate  120  by clamp-like-fixtures  520 A and  520 B, respectively. The clamp-like-fixtures  520 A and  520 B are formed as part of the base plate  120  when the base plate  120  is made of a plastic material through an injection process. The ends of the retention spring  130  are squeezed in tightly fit gaps of the fixtures  520 A and  520 B, respectively, and are fastened securely thereby. 
   Referring again to  FIG. 5A , the concave space  312  in the groove  112  has a shape that allows it to accommodate the protruding part of the retention spring  130 . As shown in  FIG. 5A , the slopes  312 A and  312 B on the surface of the concave space  312  serves to facilitate the sliding of the sliding cover  110  while overcoming the spring force of the retention spring  130 . Similar to the slopes  130 A and  130 B, the slopes  312 A and  312 B on the concave space  312  are also symmetrical, as the sliding cover  110  needs to slide in both up and down directions. 
     FIG. 5B  shows that the concave space  312  has slid away and disengaged from the retention spring  130 . The flat surface of the groove  112  depresses the retention spring  130  into the slot  425  on the edge  126  of the base plate  120  (see  FIG. 4 ). Disengaging the concave space  312  from the retention spring  130  needs to overcome the urge of the spring force of retention spring  130 . The slopes  130 A and  130 B on the retention spring  130  as well as the slopes  312 A and  312 B on the concave space  312  affect how much force is required to disengage the concave space  312  from the retention spring  130 . The gentler the slopes the easier the disengagement. With proper selection of the retention spring  130  and proper arrangement of the slopes  130 A,  130 B,  312 A and  312 B, the engagement of the concave spaces  312  and the retention springs  130  can be made just enough to prevent a toddler from sliding open the sliding cover  110 , while an older person can easily do so. 
   Referring again to  FIGS. 5A and 5B , the concave space  312  on the groove  112  is just a ditch in an otherwise straight contour of the groove  112 . Apparently when the wall of the groove  112  is thin enough the concave space  312  will include an opening on the wall of the groove  112  without affecting the function of the concave space  312 . A skilled in the art may also recognize that the retention spring can be formed on the sliding cover and the corresponding concave space can be formed on the base plate, and their engagement can just as well hold the sliding cover in place. In fact, the important slopes  130 A and  130 B do not have to be part of the retention spring  130 . A general spring loaded member may be employed as long as it has two sloped surfaces similar to the slopes  130 A and  130 B, respectively, and a spring urges the two sloped surfaces to protrude above the surface of the base plate. 
   Although the present invention discloses an embodiment with the electrical sockets  124  separated from the base plate  120 , one having skills in the art would recognize that the sliding cover locking mechanism using the combination of the retention spring  130  and the concave space  312  may be applied to other types of electrical socket assemblies such as the one with the base plate  120  integrated to the electrical sockets  124 . 
   The above illustration provides many different embodiments or embodiments for implementing different features of the invention. Specific embodiments of components and processes are described to help clarify the invention. These are, of course, merely embodiments and are not intended to limit the invention from that described in the claims. 
   Although the invention is illustrated and described herein as embodied in one or more specific examples, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention, as set forth in the following claims.