Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02490427 2004-12-16
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LIVE CIRCUIT INDICATOR FOR PLUGS AND CONNECTORS
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority pursuant to 35 U.S.C. 119(e) from U.S.
Provisional Patent Application having application No. 60/450,961, filed
February 28,
2003.
BACKGROUND OF THE INVENTION
1. Field
This invention relates generally to electrical connectors and more
particularly to a
means for indicating that the contacts of a plug or connector are electrically
connected to
a live source of power.
Extension cords, particularly those that are made by a user by connecting a
connector and a plug to the ends of a cable having a specific length and sized
to carry a
maximum current, are typically used both indoors and outdoors to provide
electrical
power for either a general purpose or a specific use. For example, when used
as a general
purpose conductor, the extension cord may be used to supply power to a lamp, a
portable
work light, a power tool, a surge protector such as is used to power a
computer, a window
mounted air conditioner, etc. When the extension cord is used outside, it may
be used to
supply power, on a temporary or semi-temporary basis, such as to a boat moored
at a boat
slip. In each instance, when an extension cord is first connected to a load,
the user must
usually trace the conductor back to the plug to make sure that it is plugged
into a
receptacle. However, at this time, the user has no indication that the
extension cord is
connected to a receptacle that is connected to a live source of power.
Therefore, what is
needed is a connector, which can also be a plug, that can indicate if it is
connected to a
live source of power. Additionally, the connector should look like a standard
connector
and be wired to a conductor in the same way that a regular connector is wired.
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SUMMARY OF THE INVENTION
The present invention relates to a method and apparatus for indicating that
the line
contacts of a connector are electrically connected to a live source of power.
In the
invention, a live circuit indicator module has an LED/resistor/diode series
circuit
connected between the tops of the line contacts of a connector or prongs of a
plug to
indicate if the prongs or contacts are connected to a live source of power. In
operation,
the LED of the series circuit shows by glowing that the prongs of a plug or
contacts of a
connector are actually connected to a live source of power.
In this invention, the electrical device, such as a plug, has at least two
blades or
prongs for insertion into a receptacle or connector. An electrical cable
having at least two
line conductors and a ground conductor extends into the housing of the plug
and is
connected directly to the blades of the plug. A live circuit indicator module
is located
within the plug for indicating, by means of a light, such as an LED, that the
line prongs of
the plug are connected to a live source of power. The housing includes at
least one
opening located adjacent to the light source located within the plug to
provide a visual
indication to a user that the prongs are connected to a live source of power.
As used
herein, the term live source of power is understood to mean that the prongs
are connected
to a source of potential of, for example, 120V, 240V, more or less, etc.
The module for indicating that the prongs are connected to a live source of
power
is self contained, can be pre-assembled and is located within the plug to
become an
integral part of the plug before the prongs of the plug are connected to the
electrical line
conductors. The series circuit of the live circuit indicator module is
electrically coupled
to the prongs by means of springs ,which are located in passageways in the
module and
the back cover to connect the LED/resistor/diode series circuit in the module
directly to
the prongs of the plug. The springs extend through the insulating body member
of the
module in which the series circuit is located. In operation, when the prongs
of the plug
are connected to a source of potential, the LED will glow. In the absence of a
potential
on the prongs of the plug, the LED will not glow. Thus, with this invention, a
user can
readily determine if power is being applied not just to the plug, but to the
blades of a plug
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by looking for the light in the plug. If the LED is lit, then the prongs of
the plug are
connected to a live source of power.
The live circuit indicator module does not alter the way the connector (or
plug) is
wired. A connector (or plug) with the live circuit indicator module, here
disclosed, looks
the same and is wired the same way as a connector (or plug) which does not
have a live
circuit indicator module.
The housing of the plug contains alignment means for~positioning the light
emitting means next to an opening in the cover of the plug to insure that a
user can see if
the light emitting means is on or off.
With this invention a user can readily determine if power is being applied to
the
contacts of a plug or connector by looking for a light in the window of the
plug.
This invention has been described in relation to a form of electrical
connector, it
being understood however, that other types of electrical connectors such as
electrical
receptacles, screw type connectors or any similar form of electrical connector
may utilize
1 S the live circuit indicator module here disclosed. Further, it is to be
understood that this
invention can be used with two line (hot and neutral) conductor cables for
determining if
a plug or a connector is connected to a live source of power.
The foregoing has outlined, rather broadly, the preferred feature of the
present
invention so that those skilled in the art may better understand the detailed
description of
the invention that follows. Additional features of the invention will be
described
hereinafter that form the subject of the claims of the invention. Those
skilled in the art
should appreciate that they can readily use the disclosed conception and
specific
embodiments as a basis for designing or modifying other structures for
carrying out the
same purposes of the present invention and that such other structures do not
depart from
the spirit and scope of the invention in its broadest form.
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BRIEF DESCRIPTION OF THE DRAWINGS
Other aspects, features and advantages of the present invention will become
more
fully apparent from the following detailed description, the appended claims
and the
accompanying drawings in which similar elements are given similar reference
numerals.
Fig. 1 is an exploded perspective view of one form of electrical connector
incorporating a live circuit indicator module for indicating if the contacts
of a connector
are connected to a live source of electrical power in accordance with the
principles of the
invention;
Fig. 2 is a bottom view of the connector of Fig. 1 showing the ground opening
and
i0 the two line openings;
Fig. 3 is a perspective view of the back cover of the connector which is
located
above the contacts of the connector and below the live circuit indicator
module;
Fig. 4 is a top view of the live circuit indicator module showing the series
circuit
for indicating if the contacts of the connector are connected to a live source
of electrical
power;
Fig. 5 is a perspective view of the cover of the top portion of the connector;
Fig. 6 is a perspective view of the lower portion or body of the connector
showing
spring contacts about to be placed into passageways in the back cover to make
electrical
contact with the tops of the line contacts that are to be connected to line
conductors;
Fig. 7 is a perspective partially exploded view showing how the live circuit
indicator module fits on the top of the back cover;
Fig. 8 is a perspective view of the body of the connector including the live
circuit
indicator module ready for positioning within the cover; and
Fig. 9 is an exploded perspective view of the body of the plug showing the two
springs about to be inserted into openings in the back cover to provide a
conductive path
between the prongs of the plug and the circuit in the live circuit indicator
module.
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DETAILED DESCRIPTION
FIG. 1 shows an exploded perspective view of one form of an electrical
connector
within which is a live circuit indicator module for indicating the presence of
electrical
power at the contacts in accordance with the principles of the invention. The
connector
5 10 has a cover 12 adapted to be positioned over the top and secured firmly
to the body 16
with screws 24. The connector supports a pair of line contacts and a ground
contact (not
illustrated). In the case.of a plug, prongs extend outward from the bottom
surface of the
plug to provide a standard three blade grounded plug. Power is supplied to the
plug or
connector by a three wire cable (not illustrated) having two line conductors
and a ground
conductor which extend into the cover and connect to the line contacts/blades
and the
ground contact/blade. A clamping means is provided to hold the three wire
cable in
position relative to the connector.
In accordance with the principles of invention, at least one window opening 14
is
provided in the cover 12. The window extends into the hollow interior of the
cover. A
light generating means such as an LED located in a live circuit indicator
module is
positioned behind the window and is visible through the window opening 14.
The wires of the conductor are stripped of insulation at the ends and are
inserted
into the openings 30 for attachment to the contacts of the connector. The
inward end of
each line contact includes a connection screw and a clamp assembly for
securing a
conductive lead wire in electrical contact with the contact. In a similar
manner, the
inward end of the ground contact includes a screw and clamp assembly for
connecting a
ground lead wire thereto. Insertion of the wires into openings 30 and clamping
the wires
to the contacts electrically connects each wire to a contact of the connector.
Referring to Fig. 2, there is illustrated a bottom view of the connector of
Fig. 1
showing three openings. Behind opening 17 is the ground contact and behind
openings
18 and 20 are the line contacts. Three screws 24, see Fig. 1, extend from the
bottom
surface through the body 16 of the connector to engage the cover 12.
Tightening the
screws 24 locks the cover 12 to the body 16 where the lower edge 26 of the
cover
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engages the upper edge 28 of the body of the connector. Alignment means is
provided to
align the cover with the body and the window in the cover with the LED of the
live
circuit indicator module.
When the cover is positioned over the top portion of the body, live circuit
indicator module 40 and back cover 50 of the plug are located within the cover
(Fig. 1 ).
Fig. 3 is a perspective view of the back cover 40 of the connector. The
openings
30 are sized to receive the conducting wires of the cable which supplies power
to the
contacts of the connector. The back cover has two passageways for receiving
springs.
The openings are positioned to be in alignment with the top of the connector
which is
connected to the line conductors and with the conductive pads 52, 54 (see Fig.
4) of the
LED/resistor/diode circuit located in the live circuit indicator module when
the live
circuit indicator module is positioned onto the top of the back cover.
Refernng to Fig 4, there is shown the top view of the live circuit indicator
module
40. The module has three openings 56 sized to receive the projections 58 (see
Fig. 3) into
which the conducting wires of the cable are located. Located on the top
surface of the
module 40 is the series circuit for detecting the presence or absence of power
at the
contacts of the connector. The circuit comprises a conductive pad 52 connected
to a
diode 58, an LED 60, a resistor 62 and a second conductive pad 54, all
connected in
series. The LED is positioned to be aligned with and located behind the window
14 in
the cover when the connector is assembled. The pads 52, 54 are positioned to
be in
alignment with the top of the passageways in the back cover which contain the
springs.
When the live circuit indicator module is positioned on top of the back cover,
the
conductive pads 52,54 make electrical contact with the tops of the two
contacts connected
to the line conductors by means of springs located within the openings in the
back cover.
Thus, a series circuit is established from the top of one line connected
contact through
pad 52, diode 58, LED 60, resistor 62, and pad 54 to the top of the other line
connected
contact.
In operation, the LED is on when power is applied to the line connected
contacts,
and the LED is off when the line connected contacts are not connected to a
live source of
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power. Thus, with this invention, a break in either of the line conductors
will be
indicated by the off state of the LED.
Refernng to Fig. 5 there is shown a perspective view of the top portion of
cover
12 of the plug or connector. The cover contains a window 14 which is aligned
to allow
S light from the LED to pass through for viewing by a user. A clear or colored
lens can be
positioned in the opening to prevent moisture and dirt from entering the
interior and
better allowing a user to see if the LED is on or off. If desired, the lens
can be colored
green or red or another color to emphasize the state of operation
(conductivity) of the
plug or connector. The top of the cover supports a cable clamp to prevent the
cable from
being pulled out.
Fig. 6 is a perspective view of the body of the connector without the live
circuit
indicator module and the cover and showing the two springs 63: Springs 63 are
located
in the passageways 65 of the back cover to electrically connect the conductive
pads 52,
54 to the tops of the contacts of the connector that are connected to the line
conductors.
Fig. 7 is a perspective partially exploded view showing the live circuit
indicator
module about to be positioned on the top of the back cover. The back cover and
the live
circuit indicator module have alignment means to insure that the springs 63
make
electrical contact with the tops of the contacts of the connector that will be
connected to
the line conductors. The same or another alignment means also insures that the
LED will
be in alignment with and located behind the window in the cover when the cover
is
attached to the body of the connector to permit light from the LED to be seen
by a user.
Fig. 8 is a perspective view of the body of the connector showing the live
circuit
indicator module in position on top of the back cover. The live circuit
indicator module
can be heat staked to the back cover or held in place by screws, epoxy or the
like.
Fig. 9 is an exploded perspective view of the body of the plug showing the two
springs prior to being inserted into the passageways in the back cover to make
contact
with the tops of the prongs which are to be connected to the line conductors.
Thereafter,
the live circuit indicator module is placed on top of the back cover and, by
means of
alignment means, the conductive pads 52, 54 are located to make contact with
the tops of
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the springs to electrically connect the series circuit of the live circuit
indicator module
across the two piongs of the plug which are to be connected to the line
conductors.
While there have been shown and described and pointed out the fundamental
novel features of the invention as applied to the preferred embodiment, it
will be
understood that various omissions and substitutions and changes of the form
and details
of the method and apparatus illustrated in the operation may be done by those
skilled in
the arr, without departing from the spirit of the invention.
