Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to electrical connectors such as are
commonly found in homes and other structures and that include an
electrical receptacle, usually mounted in a wall or other surface or
forming part of an extension cord or the like, and a plug that is
adapted to be inserted into the receptacle for the transmission of
electrical power from the receptacle to another electric powered
device or through a cord.
The need for safety-type electrical connectors has long been
recognized. It is well known that children are particularly susceptible
to injury through playing with or using the presently available electrical
connector units. For example, a child may be severely injured
through inserting hairpins or other conductive objects into a
standard electrical receptacle or by shorting across the electrical
prongs of a plug that is only partly inserted into an electrical
receptacle. It is desirable, therefore, that a safe electrical
connector be constructed such that metallic objects inserted into the
receptacle of the connector will not automatically come in contact
with electrical connections to complete a circuit. It is also desirable
that some means be provided to prevent contact of the prongs of the
plug of the connector with the electrical contacts of the receptacle
until such time as the plug has been fully inserted into the receptacle,
that the fully inserted plug be securely locked into the receptacle,
and that the connector be constructed such that a conductive member
cannot be connected across prongs of a fully inserted plug.
There are a number of patents disclosing electrical connectors
wherein a plug that is inserted into a receptacle must be turned
before electrical contact is made through the plug and in order to
provide a secure lock between the receptacle and the plug. However,
so far as I am aware, these proposed structures have not been
commercially acceptable. It is believed that the lack of success of the
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prior known structures is due to their complex construction, the expense
involved in producing them, and, in some cases at least, because they are
not sufficiently child-proof.
Principal objects of the present invention are to provide an
electrical connector that can be economically produced, readily installed,
safely and easily used by those persons mature enough to properly use the
connector, and difficult for a child to use in such a manner that he may
be shocked or burned.
Another object is to provide an electrical connector having a
receptacle that can be readily installed in place of the electrical recep-
tacles commonly in use.
Still other objects are to provide an electrical connector of the
locking type, wherein the plug component includes polarity oriented prongs
and a ground prong, and wherein the receptacle contains openings to receive
the prongs while maintaining electrical polarity and insuring a good
ground contact.
According to a broad aspect of the present invention, there is
provided an electrical connector comprising a receptacle having a face plate
with one display face and a circuit face, at least one set of openings
through the face plate, at least two openings of the set being slots, elec-
trical contact members offset from but adjacent, respectively, to the two
slots of the set, electrical connector terminals on the circuit face of the
face plate, circuit means on the circuit face respectively interconnecting
the electrical connector terminals with the electrical contact members; and
an electrical plug having a pluralitv of electrical prongs projecting from
one face of said plug, a pair of said prongs constituting circuit prongs
and each having a portion extending from the plug a distance at least equal
to the thickness of the face plate and an angled portion extending therefrom,
said angled portions being in essentially the same plane, being shaped to
fit through the slots of a set of openings through the face plate, and being
arranged to engage the electrical contact members when sald prongs are
inserted through the face plate and are turned conjointly as the electrical
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plug is tu~ned.
Additional objects and features will become apparent to those
skilled in the art from the following detailed description and claims,
taken with the accompanying drawings.
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Fig. 1 is a perspective view of the connector of the invention,
with the receptacle mounted in a wall and with one plug inserted into
the receptacle, and the other plug separated therefrom;
Fig. 2, a perspective view taken at the end of the plug from
which the prongs thereof project;
Fig. 3, a view like that of Fig. 1, but with the receptacle
pivoted to a lowered or open position;
Fig. 4, a view like Fig. 1, showing another embodiment of
the invention, with the plug removed from the receptacle;
Fig. 5, a view like Fig. 2, but showing the plug of Fig. 4; and
Fig. 6, a view like Fig. 3, but showing the embodiment of
Fig. 4.
In the preferred embodiment of the invention illustrated in
Figs. 1 and 2, the electrical connector, shown generally at 10,
includes a receptacle 11 and at least one plug 12.
The receptacle component 11 comprises a face plate 13 having
one display face 13a and an opposite face 13b, having printed circuit
leads thereon. Spaced apart sets of openings 14 and 15 each include
a central hole 16 and slots 17 and 18, respectively, at opposite
sides of the hole 16. Slots 17 and 18 include arcuate portions 17a
and 18a, respectively, with each arcuate portion having a center of
rotation at the middle of the hole 16. Slot 17 has another portion 17b
at one end of the arcuate portion 17a and extending substantially
normal thereto. Slot 18 has a substantially L-shaped portion 18b, one
leg of which is connected to one end of the arcuate portion 18a. So
constructed, the slots 17 and 18 are shaped to conform to the
prongs 19 and 20 of the electrical plug lZ.
Prong 20 extends from the face 22 of plug 12 and is angled
at 20a to extend substantially normal to the portion of the prong
projecting from the plug.
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Prong 19 also extends from the face 22 of plug 12 and is
angled at 19a to extend substantially normal to the portion of the
prong projecting from the plug, and in a direction opposite to that
of 20a. Prong 19 has a further angled portion 19b, extending
substantially normal to the section 20a and in the same plane as the
sections 19a and 20a.
Plug 12 preferably has a body 23 that is molded to an
electrical cord 24, such that the prongs 19 and 20 are electrically
connected to the circuit wires 25 and 26, respectively, of the cord.
Ground wire 27 of the cord is also connected to a central, straight
prong 28 that projects from the face 22 of plug 12. Face 22 is
preferably formed as one side of an enlarged head 29 on the end of
body 23. The enlarged head effectively prevents the fingers of a
user of the plug from slipping along the body 23 and into engagement
with the prongs 19 and 20 or from blocking locking movement of the
plug .
An electrical contact member 30 is placed adjacent to one
of the ends of each of the slots 17 and 18 on the rear surface of
face plate 13 opposite to that through which the prongs of the plug
20 are inserted. The contact members are positioned such that after
the prongs have been inserted and turned, i . e . in a clockwise
direction, the prongs each come into engagement with a contact
member. Further turning will then move the prongs over a raised
detent 30a of each contact member so that the prongs will not
inadvertently turn back to release the plug from the receptacle.
The contact members 30 are each electrically connected to
printed circuit leads 31 formed in the rear surface, i.e. circuit face
of the face plate 13 and the leads each extend to and are electrically
connected to a screw-type electrical connector 32\. Thus, after the
prongs 19 and 20 have been inserted through the face plate 13 and
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have been turned within the arcuate portions of slots 17 and 18
into engagement with contact members 30, a circuit is completed from
power wires connected to the screw type connectors 32, leads 31,
contact members 30, prongs 19 and 20 and cord 24 to whatever
electrically operated device may be connected to tke other end of
the cord 24. Because the prongs 19 and 20 are of different shapes
and will fit only through the slots shaped to receive them, electrical
polarity between the receptacle and the plug is maintained.
The grounded central prong 28 fits through the eentral hole 16
at the same time as prongs 19 and 20 are respectively inserted
through the slots 17 and 18 and the prong 28 then serves as a pivot
shaft about which the prongs 19 and 20 are rotated. A flexible
conductive bar 33 is electrically connected to a screw-type
connector 34, adjacent to the screw-type connectors 32 and the bar
extends across each hole 16 at a location just slightly off-center.
Each prong 28 has a rounded tip, and as the prong is inserted
through a hole 16, it engages the bar 33, which flexes to allow full
insertion of the prong 28, and that then tends to bind the prong
against the edge of hole 16, to insure better holding of the plug
within the receptacle.
While it will be apparent that the face plate 13 can be used
as an end of an extension cord or with any conventional outlet box,
such as is shown at 36, it can also be used with much shallower boxes
than are conventionally used, since there is no separate, bulky
socket to be inserted in the box. The power lines coming into the
box may enter through knock-outs in the rear, top or sides of the
box, as is conventional.
It will also be apparent that the face plate 13 can be
attached to the box by top and bottom screws inserted through the
face plate and threaded into holes provided therefor in the box.
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However, when the face plate is to be used with an outlet box~ it
is preferred that a hinge 37 be formed at one end of the face plate,
with a flap 38 extending from the hinge. A screw 39 is then
inserted through a hole in the flap to fasten the flap to one end of
the box 36. The plate 13 can then be pivoted from a position
projecting out from the box, at which position the power line wires
can be attached to the screw-type connectors and a raised position
wherein the plate covers the box and is flush against the wall in
which the box 36 is recessed. A screw 40 is inserted through a hole
39a in the face plate to secure the face plate in the raised position.
While the prongs 19 and 20 are here shown as having a
circular cross-section, it will be apparent that they could as well
be made of flat stock~ with a rectangular cross-section. If the prongs
are made somewhat resilient and made to properly project from the
face of plate 13 they will securely engage the contact members 30
after moving over detents 30a to make a non-sparking contact and
to prevent withdrawal of the plug with a prior intended turning of
the plug. Once the turning is initiated to release the plug from
the receptacle and even before the prongs are aligned with the slots
to allow withdrawal, the circuit connection between the receptacle
and the plug is broken. Thus, there is no possibility that contact
elements having a current therethrough can be engaged by a user.
It is also preferred that the enlarged head 29 have a
projecting peripheral ring 41 that will fit into a groove 41a provided
in the face plate 13 and surrounding the openings 16-18. With the
ring 41 extending into the groove 41a when the plug is fully inserted
and an electrical circuit is completed through the connector 10, there
is no possibility that a knife blade or other thin conductive member
could be slipped between the plug 12 and the face plate 13 to short
across the prongs 19 and 20.
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While the embodiment of Figs. 1-3 has shown an arrangement
including printed circuit leads, screw-type connectors, and the like,
it should be recognized that these are preferred components, but
that other conventional components can be alternatively used. Also,
while the illustrated preferred embodiment shows a central grounding
prong and diametrically placed polarity oriented plugs that rotate
about the central grounding plug, other arrangements could be used.
For example, a non-conductive central post (not shown) could be
used and all prongs, including the grounding prong could be radially
spaced around the central post. The radially spaced prongs would
all make contact with contact members provided at the ends of
openings in the face plate through which the prongs are inserted.
Polarity would still be maintained by having one prong of a unique
shape and one opening through the face plate to receive the uniquely
shaped prong.
Another embodiment of the invention is shown in Figs. 4-6.
In this embodiment, the connector, shown generally at 45, includes
a face plate 46, constructed essentially like the face plate 13,
previously described, but including a set of openings comprising
slots 47, 48 and 49, all radiating from a central opening 50. Slot 49
has an angled tip 49a to make it unique from slots 47 and 48.
Connector 45 also includes a plug, shown generally at 51.
Plug 51 has an insulated, non-conducting member 52 projecting
through and from a face 53 of an enlarged head 54. The head 54,
like the head 29, previously described, preferably has a projecting
ring 55 that will fit into a groove 56 on the face plate 46 to prevent
shorting across electrically connected prongs.
Three prongs 57, 58 and 59 project through and from face 53
and are held separated by member 52. A power wire having a ground
wire 60 and circuit wires 61 and 62 extends through a housing
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portion 63 to be soldered, clamped or otherwise respectively connected
to the prongs 57, 58 and 59. Prong 59 is angled at 59a so that it
will have a shape corresponding to slot 49 and so that polarity will
be maintained when the prongs are inserted through the face plate and
are turned to be in contact with contact members 64, 65 and 66,
positioned adjacent to the slots at the circuit face 46a of face plate 46.
Through circuit leads 67, 68 and 69, the contact members 64, 65
and 66 are respectively connected to screw-type terminal
connectors 70, 71 and 72, to which the ground wire and electrical
contacts of a power line are connected.
