Electrical outlet safety cap with rotatable prongs

A safety cap for an electrical outlet, including a face plate having an opening, a rotatable mounting element including a disk positioned in the opening of the face plate, and at least one prong having one end attached to one side of the disk and extending substantially normal to the face plate, the at least one prong having a transversely extending member along one edge for fixing the face plate to the electrical outlet.

TECHNICAL FIELD 
This invention relates generally to safety caps for electrical wall 
outlets, and more particularly, to a cap with rotatable prongs to prevent 
unintended removal of the safety cap. 
BACKGROUND ART 
Small children can be protected against electric shock and injury by 
inserting safety caps in electrical outlets so that metal objects cannot 
be easily inserted into the receptacle slots. 
The prior art includes several safety plug devices consisting of caps 
having electrically non-conducting prongs which can be inserted into the 
outlet holes as shown in FIG. 1. As children grow older, they often 
discover how to remove these plugs from the socket simply by observing 
others remove the plugs or by playing with the caps in such a way that 
they eventually learn how to pry them from the socket. A need therefore 
exists for means to help prevent the plug from being unintentionally 
removed from the socket. 
There are devices in the prior art for retaining a safety cap near an 
outlet when not in use. U.S. Pat. No. 5,017,148 issued to Buckshaw, for 
example, discloses safety plugs attached to a tether. The tether is 
attachable to the face plate of the outlet to retain the plugs near the 
outlet when the plugs are not in use. The Buckshaw device and other 
similar tether devices do not disclose means for retaining the prongs of 
the plugs in the outlet during use, however. 
There are likewise numerous devices attachable to a plug connected to an 
electrical appliance to prevent the plug from being pushed into an 
electrical socket, such as U.S. Pat. No. 4,407,554, for example. Such 
devices are useful to prevent a particular device from being operated but 
do not address the problem of other electrically conductive objects, such 
as metal keys, being pushed into an electrical outlet by a child. 
Accordingly, the present invention is directed to overcoming one or more of 
the problems as set forth above. 
DISCLOSURE OF THE INVENTION 
In one embodiment of the present invention, a safety cap for an electrical 
outlet includes a plug face plate and two prongs, each prong having a 
transversely extending member along an edge and being attached to the plug 
face plate at one end with rotatable mounting means. The rotatable 
mounting means includes a disk that is positionable in a similarly sized 
opening in the plug face plate. The opening is sized to retain the disk by 
frictional force while allowing the disk to be rotated when enough force 
is applied to overcome the frictional force. The prongs are substantially 
parallel to slots in the electrical outlet when the safety cap is inserted 
into the outlet. After the prongs are inserted, the present invention 
includes means for rotating the disks until the transversely extending 
members engage the edge of an inner portion of the electrical outlet, 
which prevents the safety cap from being removed until the prongs are 
rotated back to their original position. A cover may be placed over the 
safety cap to prevent access to the means for rotating the disks.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring to the drawings, FIG. 2 shows an exploded view of a preferred 
embodiment of the present invention for a safety cap 10 for an electrical 
wall outlet 12 including a face plate 14 with one, two, or three openings 
16 therein. The openings 16 are spaced so that each one overlays a prong 
receptacle slot 18 in the electrical wall outlet 12. A disk 22, having a 
prong 20 attached to one side of the disk 22, is placed within each of the 
openings 16 for rotatable mounting therein. The prong 20 may have any 
desired cross-section, such as a rectangle (as shown), a circle, or an 
ellipse. As shown in FIG. 3, the disk 22 has an annular groove 23 around 
at least a portion of the periphery to provide means for retaining the 
disk 22 in the opening 16. The openings 16 in the face plate 14 are sized 
to allow the disk 22 to rotate and the edges of the openings 16 may be 
rounded or beveled to engage the annular groove 23 of the disk 22. 
Standard electrical wall outlets 12 have inner, electrically conductive 
walls (not shown) extending some distance into each slot 18 from the 
opening of the slot 18. The length of the prong 20 extends into the 
receptacle when the prong 20 is inserted in the electrical wall outlet 12. 
The prong 20 is long enough so that a transversely extending member 26 
along one side engages the edge of the inner wall of the electrical wall 
outlet 12 when the prong 20 is rotated in either a clockwise or 
counter-clockwise direction. The transversely extending member 26 may be 
placed on the upper or the lower side of the prong 20, or the prong 20 may 
include two transversely extending member 26, one on the upper side and 
one on the lower side of the prong 20. More of the prongs 20 may include a 
transversely extending member 26 to improve retention of the safety cap 10 
in the electrical wall outlet 12 when the transversely extending member 26 
of each prong 20 engages the edge of the corresponding inner wall. FIG. 3a 
shows a safety cap 14 having one prong 20 with a transversely extending 
member 26 and another prong 27 without a transversely extending member for 
a ground plug. The safety cap 14 may be retained in the electrical wall 
outlet 12 with only one prong 20 having a transversely extending member 26 
to engage the inner wall of the outlet 12. Prongs 20 including 
transversely extending members 26 may also be used in the other openings 
16 to increase retention of the safety cap 14 in the outlet 12. 
Alternatively, prongs 27 without transversely extending members may be 
used in one or two of the openings 16 to provide stability when the safety 
cap 14 is inserted in the electrical wall outlet 12. Further, in order to 
simplify construction of the present device, the safety cap 14 may include 
only one opening 16 to accommodate a rotatable disk 22 and prong 20 
assembly, while the other prongs may be fixedly attached to the safety 
cap, as currently found in the prior art safety caps as shown in FIG. 1. 
The disk 22 may include an alignment marking 28 to provide an external 
indication of the position of the prongs 20. Further, alignment markings 
28 may be included around the openings 16 in the safety cap 10 to indicate 
to the user the amount of rotation required to engage the transversely 
extending members 26 with the edge of the inner wall. 
A tab 29 extends from the periphery of the disk 22 to provide means for 
applying rotational force to the prongs 20 and disk 22. The tab 29 extends 
from and is coplanar with the flat surface of the disk 22. The tab 29 may 
be rotated by exerting force along one of the side edges of the tab 29 
using a finger or other implement. The tab 29 may be positioned on any 
portion of the periphery of the disk, however, a preferred embodiment of 
the present invention as shown in FIG. 4 includes the tab 29 positioned at 
an angle 37 relative to the vertical direction when the prongs are not 
rotated. 
Alternative means for applying rotational force to the disk 22 include a 
pin 30 extending from the tab 29 as shown in FIGS. 2 and 3, and a bar 32 
as shown in FIGS. 4 and 5. The pin 30 may include means for retaining and 
stabilizing the bar during use, such as an indention 34 as shown in FIG. 
3. The bar 32 has one or more openings 36 for engaging the pins 30 and 
rotating the disks 22 in the face plate 14. The bar 32 may include one 
opening 36 so that one disk 22 may be rotated at a time. Alternatively, 
the bar 32 may be constructed with two openings 36 that fit over both of 
the pins 30 at the same time. To further facilitate rotation of the tabs 
28 with the bar 32, a contoured, raised platform 38 is attached to the bar 
32 to provide means for stabilizing the operator's finger or other 
implement that is used to exert sideways force on the bar 32. 
A further alternative means for applying rotational force to the disk 22 is 
shown in FIG. 5 where the tab 29 includes one or more openings 40 and the 
bar 32 includes one or more pins 42 that may be inserted in the openings 
40. The orientation of the tabs 29 at the angle 37 facilitates applying 
rotational force to the disk 22 with a bar 32 as movement of the bar 32 is 
substantially horizontal. 
The disk 22 may include slots 44 to accommodate various types of screw 
drivers (not shown) as a means for applying rotational force to the disk 
22. The slots 44 may be included in addition to or instead of the tab 29 
as means for applying rotational force to the disk 22. 
The present safety cap 10 and prongs 20, 27 are constructed of electrically 
non-conductive materials that are strong enough to withstand insertion and 
removal from electrical outlets 12. To use the present safety cap 10, the 
operator inserts the prongs 20, 27 of the safety cap 10 into the 
electrical outlet 12 until the face plate 14 abuts the outlet 12. The 
operator then uses one of the means for rotating the disks 22 disclosed 
hereinabove to rotate each prong 20 having a transversely extending member 
26 until the transversely extending member 26 engages the edge of the 
inner wall of the electrical outlet 12. If the particular embodiment of 
the present invention includes markings 28 around the edge of the openings 
16 and the disk 22, then the operator may use these to indicate the prong 
20 is in the engaged and disengaged position. 
FIG. 6 shows an alternate embodiment of the present safety cap 10 having a 
substantially circular face plate 50 and a rim 52 around the periphery of 
the face plate 50. The rim 52 includes means for securing a cover 54 over 
the face plate 50 and rim 52 to prevent unintended rotation of the prongs 
20 that may occur when the disks 22 and the tabs 29 are left exposed. The 
rim 52 may include a thread 56 around a portion of the side to engage a 
corresponding thread (not shown) around the inner side of the cover 54. 
The bar 32 should be sized so that it may be moved within the rim 52 to 
rotate the disks 22 and the prongs 20 to the engaged position. Other means 
for covering the safety cap 10 shown in FIGS. 2, 4, 5, and 6 may be used, 
such as a snap-on cover (not shown) that is sized and shaped to fit snugly 
over the perimeter of the face plate 14 and to be held in place by 
frictional forces. 
It is anticipated that the present invention may be used not only in 
standard 120 volt electrical wall outlets, but also any other type of 
electrical outlet wherein prongs of a plug may be inserted. 
Other aspects, objects and advantages of the present invention can be 
obtained from a study of the drawings, the disclosure and the appended 
claims.