Note: Descriptions are shown in the official language in which they were submitted.
~;~472~4
SOCKET EXTENDER FOR FLUORESCENT LAMP
BACKGROUND OF THE INVENTION
This invention pertains to an apparatus for use
with fluorescent electrical lamp fixtures having socke~s at
two of its ends to extend the effective length of the
sockets and permit the use of shorter lamps.
Standard ceiling lamp fixtures for use with
fluorescent lamps are ordinarily modular in design and fit
into standard ceiling troffer modular fixtures. Many such
fixtures are designed to accept 4-foot long fluorescent
lamps, typically operating at 40 watts each. These modular
ceiling fixtures are as short as the 4-foot lamps they are
designed to acceptO Furthermore, such ceiling fixtures
generally are shallow in order to fit into the ceilings and
include a reflector spaced only a short distance from the
lamp.
In order to replace light bulbs when one or more
of the fluorescent lamps has failed, the lamps must be
removed diagonally from the fixture due to the short length
of the fixture. The metal reflector is also very close to
the installed fluorescent lamps and makes installation and
removal of the lamp even more difficult. The typical
fluorescent lamp of the rapid start type has two bi-pin
bases which mate with pairs of standard tombstone type
sockets (one located at each end) making it necessary
to twist the lamp to install it in or remove it from its
pairs of socketsO Due to the closeness of the reflector it
is often not possible to get hands or fingers around the
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1 bulb and it is therefore necessary to twist the bulb with
the fingers only which may be difficult.
Furthermore, tombstone sockets tend to be fragile,
usually being made of inexpensive plastic molding having
spring contacts therein. During the removal or inser~ion
of the lamps from the tombstone sockets, these sockets are
easily damaged neccessitating the replacement of both the
lamp and the socket. Maintenance costs for replacement of
a lamp may therefore be unexpectedly high.
In addition, it is also difficult to ins~all
lamps in modular ceiling fixtures since, in order to insure
proper alignment of the lamp pins, it is necessary to be
able to see both ends of the lamp at the same time. This
is difficult due ~o the length of the lamp. It is there-
fore necessary to insert the lamps by "feel" and this also
leads to damage to the ~ombstone sockets.
One solution to this problem would be to use a
shorter lamp bulb and a correspondingly shorter fixture in
the existing ceiling fixtures. The existing ceiling
fixtures, however, cannot accept shorter lamps since the
pins of both ends of a fluorescent lamp must be firmly
seated against the contacts in the tombstone sockets at
either end of the lamp fixture. To use a shorter lamp
in a standard 40 watt fixture, an adapter is necessary.
It is known that shorter fluorescent lamps
utilize less wattage and produce less light output then a
correspondingly longer lamp. Substitution of shorter lamps
for the standard lamp will permit a corresponding decrease
in energy usage. Where a decrease in lumens output can be
tolerated, the energy savings afforded by a shorter lamp
can be significant.
SUMMARY OF THE INVENTION
An extender for lamp sockets, particularly for use
with tombstone type sockets as used with bi-pin fluorescent
lamps, is described permitting plunger installation of
fluorescent lamps of a shorter length in ordinary tombstone
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1 socketed lamp fixtures. The socket extender includes
contacts located within a housing and electrically coupled
to pins similar to the pins of a bi-pin fluorescent lamp.
The lamp pins are rotated within the tombstone sockets to
engage with the tombstone socket contacts. The lamp is
inserted into the extender so that its pins make contact
with the spring loaded contacts therein which insertion
takes place in a direction substantially parallel to
the longitudinal axis of ~he fluorescent lamp.
It is therefore an object of the present invention
to provide a socket extender to permit the use of shorter
length light bulb in standard ceiling lamp fixtures.
It is a further object to provide energy savings
resulting from the use of shorter lamps.
Another object is to provide an adapter that
permits the installation of bi-pin base fluorescent lamps
in a plunger type installation, in lamp fixtures having
tombstone type sockets.
These and other further advantages of the present
invention will become apparent upon reference to the
annexed specification and drawings.
BRIEF DESCRIPTION OF T~E DRAWINGS
Figure 1 is an elevational view of a socket
extender according to the present invention showing a
fluorescent lamp mounted;
Figure 2 is a cross-section of the lamp socket
extender taken across line 2-2 of Fig. l;
Figure 3 is a sectional view of the socket extender
taken along line 3-3 of Fig. 2;
Figure 4 is a sectional view of the socket extender
taken along line 4-4 of Fig~ 2;
Figure 5 is a sectional view of another embodiment
of a socket extender according to the present invention,
shown partially broken away and showing orientation of lamp
pin openings in a first direction;
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1 Figure 6 is a cross-sectional view of the embodi-
ment of Fiyure 5 showing the lamp pin openings in a second
position;
Figure 7 is a sectional view of the embodiment
of Figure 5 and 6; and
Figure 8 is a sectional view of another embodi-
ment of the invention.
DESCRIP ION OF THE INVENTION
Referring to Figure 1 socket extenders 10 are
shown together with lamp 11 installed in fixture 12.
Fixture 12 is a standard lamp fixture designed to accomo-
date standard length light bulbs, typically a 4-foot, 40
watt fluorescent lamp. Fixture 12 includes a base portion
13 and a tombstone socket 14 at each end. The tombstone
sockets are of the type well known in the art in which a
fluorescent lamp is inserted by sliding it in a direction
along a line defined between the two pins of a fluorescent
light base and then rotating the lamp 90 degrees in either
direction within the tombstone socket to engage with
electrical contacts within the tombstone socket. Lamp 11
is similar to a standard fluorescent lamp except that it is
not of the standard 4-foot length, but is two to three
inches shorter and consquently draws approximately 2 watts
less than a standard 4-foot fluorescent lamp. Because of
its reduced length, lamp 11 will also provide a 4-5~
decrease in lumen output as compared to a standard 4-foot
lamp. The length of extenders 10 will be ~elec~ed to
compensate for the difference in length between lamp
11 and the standard lamp for which fixture 12 was designed.
It will be understood by those skilled in the art that the
present invention is not limited to use in fixtures de
signed to accept 4-foot lamps, but may be used with any
lamp length.
Referring to figure 2 extender 10 comprises a cup
shaped base being generally cylindrical and having one
substantially closed bottom end. As will be clear from the
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deseription below the cylindrical shape of base 15 h~s a circular
cross-section larger than the encl cap portion lla of lamp 11, Base
15 is of non-eonduetive material, for example, plastic.
Spring contaets 16 and 17 are located within base
15 and are affixed to the elosed bottom end of base 15 by
eleetrieally eonduetive pins 20 and 21,
Contacts 16 and 17 are leaf spring contacts and may
be made of, for example, phosphor bronze or a like material having
good electrical and spring characteristics, As show, each of the
eontaets 16 and 17 is of C-shaped leaf spring oriented along
parallel ehords of the cireular cross-seetion of base 15. The
length of the C-shaped leaf spring eontacts 16 and 17 is maximized
by this orientation, thus providing a maximized amount of spring
eurvature and spring travel. In use, eontacts 16 and 17 contact
fluoreseent lamp pins 22 and 23 respeetively and provide electrical
current and voltage to the cathodes of lamp 11. Contacts 16 and 17
may also be formed in an S-shaped leaf spring or as any other type
of spring known in the art. Contaets 16 and 17 should provide
~ood el~etrieal eontaet to pins 22 and 23 to eleetrieally eouple
2C them to pins 20 and 21.
Pins 20 and 21 are eoupled to eontaets 16 and 17 and
mated with tombstone soeket eontacts 14a and 14b which are
ultimately coupled to the electrical ballast (not shown) for the
lamp 11. The eleetrieal ballast may be of any type known in the
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art and is very often conveniently held in fixture base l3, Pins
20 and 21 are inserted in apertures in contacts 16 and 17 in a
frictional fit and are electrically conductive therewith. They
are thereafter inserted into the closed end 15a of base 15 once
again by frictional fit or they may be held in place~ e.g, by an
adhesive.
Plunger plate 24 is circular in shape and has a
diameter substantially equal or slightly less than the
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1 inner diameter of base 15. If base 15 has a shape other
than cylindrical, plunger plate 24 will be similarly shaped
and have dimensions and shape selected to substantially
match the inner dimensions and ~hape of a cross section o
base 15. Plunger plate 24 includes apertures 25 and 26
which receive lamp pins 22 and 23, respectively. Plunger
plate 24 is free to move in a direction along the longi-
tudinal axis of lamp 11, that is in ~he direction indicated
by arrow 25. It is not necessary, or even desirable to
permit plunger plate 24 to rotate in the directions shown
by curved arrows 28 and 29 in figure 3 since such rotation
would cause the apertures 26 and 28 to become misaligned
with respect to contacts 16 and 17 and thereby prevent good
contact between pins 22 and 23 and contacts 16 and 17,
respectively. Many methods and apparatus for preventing
the rotation of plunger plate 24 may be used, for example~
grooves or notches in the perimeter of plunger plate 24
which engage with mating longitudinal ridges in base 15 as
B shown in Fi~ure 3;
A ~ 27 is formed around an edge of base 15 to
prevent plunger plate 24 from being ejected from base 15 by
spring contacts 16 and 17. Ring 27 is an annular ring ~!
having an inner diameter substantially equal to or larger
than the outer diameter of lamp cap 11a and an outer
diameter substantially equal to the outer diameter of lamp
base 15, thus permitting lamp cap 11a to be inserted into
the inner aperture of ring 27 lamp 11, pins 22, 23 and the
subsequent electrical contact of contacts 16 and 17.
If the cross section of base 15 is selected to have a
conf~uration that is non circular, the outermost perimeter
of ~Fr27 will then be selected to define a shape substan- ~l
tially the same as the shape of the base 15. Generally,
however, the inner apper~ure of ring 27 will be circular to
accept the end cap 11a of a fluorescent lamp end cap 11a of
a fluorescent lamp to be inserted therein.
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1 ~p 27 may be fastened to socket extender base 15
by means of screws 30, 31, and 32 or by any suitable
~astening means, e.g. rivets, adhesive, etc.
B Locking clip 33 is an L~shaped clip comprised of a
first leg 34, a second leg 35, and a clip lock 36. Legs 34
and 35 are generally planar surfaces disposed at subs~an-
tially right angles with respect to one another. Clip lock
36 also describes a planner surface and extends from second
leg 35 at an angle between 90 and less than 180 degrees,
being approximately 150 degrees from the surface of leg 35
nearest leg 34. It will be noted that locking clip 33 is
so oriented that it has a longitudinal axis taken along leg
35 which i5 oriented parallel to a line intersecting the
center of apertures 25 and 26. Locking clip 36 is fas~ened
to base 15 by rivets 40 and 41 which run through apertures
in first leg 34 and into corresponding apertures in a side
of base 15. Locking clip 33 is so disposed on base 15 so
that a free space is created between the inner surface 35a
of second leg 35 and the rear surface 15a of base 15. The
~o space thus created is selected to be large enough to
accommodate a tombstone socket such as socket 14.
Locking clip 33 functions to maintain base extender
10 coupled to tombstone socket 14 even in the absence of a
lamp inserted into extender 10. Clip lock 36 extending from
second leg 35 further locates locking clip 33 in position
over tombstone socket 14. Clip lock 36 snaps over the edge
of tombstone socket 14.
Locking clip 33 is generally comprised of a spring
like material so that surface 35a of second leg 35 will
remain pressed against tombstone socket 14.
It will be clear to those skilled in the art that
devices other than rivets 40 and 41 may be used for attach-
ing locking clip 33 to base 15, for example, self tapping
screws, screws and nuts or adhesives.
During installation socket extender 10 is slid
along leg 35 so that pins 20 and 21 may enter tombstone
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1 socket 14 in the manner customarily used when inserting a
standard fluorescent lamp into a tombs~one socket. Lamp
extender 14 is then rotated 90 degrees in either direction
28 or 29 so that pin 20 and 21 lock into place in tombstone
socket 14~
This rotation also permits locking clip 33 to
assume the position shown in figures 2, 3 and 4 and stably
hold socket extender 10 in position on tombstone socket 14
with clip lock 36 snapping over a lateral edge oE tombstone
socket 14. Since locking clip 33 is L-shaped, it can
rotate around the tombstone socket~
The socket extender thus installed on both ends of
fixture 12 receives a fluorescent lamp which is placed so
that its pins 22 and 23, are aligned with apertures 25 and
26 in floating plunger plate 24. Lamp pins 22 and 23
presses agains~ the spring contacts 16 and 17 . Cap 11a
will thus be inserted partially into base 15. Thereupon
the other end of the fluorescent lamp will clear the outer
most portion of the socket extender installed at the other
end of the fixture and then may be lifted into position and
its corresponding pins 22 and 23 inserted into correspond-
ing appertures 25 and 26~ Upon release of the pressure the
contacts 16 and 17 at both ends of the lamp will maintain
contact against their associated pins at the ends o~ the
fluorescent lamp. There is thus no neccessity for twisting
or rotation of the lamp. Furthermore, since the lamp is
now two to three inches shorter than a standard lamp, it is
easy to insert or remove 1amps from a standard fixture.
Refer now to figure 5, 6 and 7 where an alterna-
tive embodiment according to the present invention is shownin which like elements are referred to by like numerals.
In the embodiment of Figures 5, 6 and 7, the outer portion
of the socket extender 10 is not rotated to engage with the
contacts 14a and 14b of the tombstone socket; only the
inner portion is rotated as described below.
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1 As shown in figure 7 the socket extender 10
includes a hollow cylindrical shell 50 having contacts 16
and 17 therein coupled to pins 20 and 22 which are in turn
affixed to rotating plates 51 in the same manner as pre-
viously described with respect to base 15 shown in figur2
2~ Protuberances 52 and 53 are spaced apart from one
another and are rigidly affixed to rotational plate 51.
They have a substantially rectangular cross section and are
of approximately equal height.
Plunger plate 5S rests within base 50 having an
outside diameter substantially equal to the inside diameter
of shell 50. As previously discussed with respect to
plunger plate 24 and base 15, plunger plate S5 will have an
outer diameter and perimeter shape substantially matching
the inner diameter and shape of shell 50. Plunger plate 55
will also include two apertures 56 and 57 corresponding to
apertures 25 and 26 which receive the fluorescent lamp pins
22 and 23 therein.
Plunger plate 55 also includes a protrusion 60 and
a recess or slot 61. Protrusion 60, generally rectangular
in cross section extends orthogonally to the surface of
plunger plate 55 and has shape and dimension selected to
fit in the space between protruberances 52 and 53. Slot 61
is adapted to receive a turning force such as may be
applied with a screwdriver. Thus, plunger plate 55 unlike
plunger plate 2~ of the previously described embodiment, is
designed to rotate in a direction indicated by arrcws 28
and 29 in figure 6.
When a turning force is applied to plunger plate
55, as for example, by a screwdriver inserted into slot 61,
rotational plate 31 will also rotate in the same direction
by virtue of the coupling engagement between protrusion 60
and protruberances 52 and 53. ~he socket extender of
figure 4 is coupled to a tombstone socket pins 20 and 21
and locked in place by turning of the slot 61 instead of
rotation of the shell 50.
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1 Shell 50 also include a lip 50a corresponding to
the lip 27 of the previously described embodiment. Lip
50a, as shown in figure 7, is an integral portion of casing
50. In the instance where casing 50 is molded from plastic,
lip 50a will be a integral par~ of ~he molding. Alterna-
tively, lip 50a may be applied as lip 27 with rivets, ad-
hesives or other attaching devices.
The socket extender of figure 60 also includes
support clip 65 which is affixed to casing 50 by rivets 70
71, 72 and 73. Support clip 65 may also be attached to
casing 50 by self-tapping screws, adhesives or other
methods known in the art
Support clip 65 is generally of sheet metal formed
to have a rectangular recess 65A between two outer planar
regions 65B and 65C attached to casing 50. Rectangular
recess 65A has dimensions and shape adapted to receive a
tombstone socket. The metal support clip 65 performs the
same functions as locking clip 33 and retains socket
extender 10 as shown in figure 5, 6 and 7 on a tombstone
socket without a lamp being inserted therein. Unlike
locking clip 33, metal support clip 65 is fastened around
its perimeter to casing 50. Clip 65 need not be turned
about tombstone socket 14 since appropriate contact between
pins 20 and 21 and the contacts 14A and 14B of tombstone
sockets 14 is accomplished by means of the twising or
rotation of rotating plate 51.
Insertion and removal of a fluorescent lamp from a
ceiling fixture equipped with the socket extenders 10 of
figures 5, 6 and 7 is performed in the same manner as
described for the socket extenders of figures 2, 3 and 4.
This socket extender is utilized by sliding the rectangular
recess 65a of metal support clip 65 over the end of the
tombstone socket which is thus held in place. As previously
stated, and as in the normal installation of a fluorescent
lamps the pin 20 and 21 must be properly aligned so that
they may slide into the tombstone socket and then be
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1 rotated by means of a turning force supplied through slot
61.
Figure 8 is a cross-sectional view of an embodi-
ment of the invention having the same external configura-
tion shown by and described for Figure 3, but having adifferent internal configuration. In Figure 7 the embodi-
ment plunger plate 80 includes two recesses 82 and 84 in
alignment with apertures 26 and 28, respectively. Hollow
brass cup contacts 86 and 88 are seated within recesses 82
and 84 being biased into tha~ position by compression
springs 96 and 98. Cup contacts 86 and 88 are generally
elongate, hollow cylinders having closed ends 83 and 85
and open ends 87 and 89, respectively.
Pin support plate 90 is disposed opposite plunger
plate 80 and includes wells 92 and 94 extending from the
base 91 of support plate 90, and having an internal diameter
sufficient to receive and permit sliding motion of contacts
86 and 88.
Compression springs 96 and 98 are located within
the interior of contacts 86 and 88 and wells 92 and 94,
within which they are supported, and may optionally be
electrically conductive.
Conductors 100 and 102 are electrically coupled by
welding to the interior of contacts 86 and 88 and further
electrically coupled to pins 23 and 22, which are seated in
pin support plate 90. Conductors 100 and 102 can also be
electrically coupled by other methods known in the art.
In operation, a fluorescent lamp bi-pin contacts
are inserted into apertures 26 and 28 making contact with
cup contacts 86 and 88. Springs 96 and 98 assure stable
conduction between the lamp pins and contacts 86 and 88.
Conductors 100 and 102 in turn assure conduction between
contacts 86 and 88 and pins 23 and 22, respectively.
As described above, pins 23 and 22 are inserted
into a standard tombstone socket.
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1 The previously described socket extenders accord
ing to the present invention, when properly installed, will
provide positive pin contac~ at all times. Since there is
no improper orientation or likelihood of pins slipping off
the contact duriny installation, larnp life is enhanced.
The extenders may be easily and quickly installed without
the need for special tools or modification of existing
equipment. Additionally, the socket extenders can be
removed at any time to permit the return of a standard size
lamp to the fixture. Furthermore, ~he socket extender
provides ease of installation through the use of plunger
type sockets and consequently can lead to savings in
maintenance costs.
The use of the socket extender may also provide
substan~ial energy savings. Since the lamp is generally on
the order of two to three inches shorter than a standard
lamp, it can provide savings of two to three watts of
consumed energy with a conventional lamp, for example, an
argon filled lamp. While there are a number of reduced
energy consuming lamps which have been used to save energy
in existing lighting installations, these lamps generally
may not be used under all conditions, particularly at low
temperatures. These are often krypton-neon or krypton-argon
filled lamps which generally must be used at temperatures
above 50 degrees Fahrenheit. Even at temperatures above 50
degree Fahrenheit, such lamps may flicker and be difficult
to start. Shorter lamps using the standard argon fill gas
will still provide a savings in energy yet retain the ease
of starting o~ a standard lamp. Furthermore, lamp mainten-
ance and discoloration is the same as in regular lamps,which is generally better then that in the energy saving
krypton-neon or krypton-argon lamps.
Generally, energy saving lamps may, due to the
different requirements of lamps having this type of fill
gas, strain the ballast~ When utilizing the present
invention, the energy savings are realized without strain-
ing the ballast.
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1 For even greater energy savings, the shorter lamps
may also be made with a krypton-neon or krypton-argon fill
gas for those environments where such lamps can be used.
Thus, even greater energies savinys are possible. For
example, a typical energy saving 48-inch lamp uses 34 watts
while a 46-inch lamp would consume approximately 32 watts.
Additionally, the shorter krypton-neon or krypton-argon
filled lamps will show better starting than the standard
length lamps usins the same fill gas.
Given enough space within the socket extender
various types of electronic circuitry may be included. For
example, a transformer could be contained within the
adapter. Currently, there are lamps being sold as energy
saving lamps including a special transformer and capacitor
lS within the lamp to permit the use of a lamp having different
parameters and operating characteristics then a standard
fluorescent lamp. These lamps incorporate the ballast
system within the lamp. Thus the ballast system is
discarded every time the lamp is replaced. Insertion of
the ballast or ballast modifying system within the adapter
would permit savings upon replacement.
It would also be possible to put in a timed
cathode cut off switch so that after the lamp is operating
the heating current to the lamp cathodes is removed. This
would save much of the energy in heating and permit lower
energy consumption.
