Note: Descriptions are shown in the official language in which they were submitted.
394
The present invention relates to light string sets
of the type having incandescent lamps and/ more particularly,
to a miniaturized light string set employing series-connected
shunt-type incandescent lamps and a fusing arrangement.
The present invention is an improvement of the fused
decorative string set described and claimed in Lehmann et al
U. S. Patent 3,968,398 issued July 6, lg76.
Said Lehmann et al patent disclosed a series-connected
decorative incandescent lamp string set permitting the use
of-fine gauge wire in a series lamp circuit. Lamps at the
end of the series string which were of an unshunted type
whereas the remaining lamps in the series string were of
- a shunted type permitting continued current flow to the lamp
in the event of filament burnout. The unshunted lamps at
each end of the string were intended to serve as a fuse for
the entire set, since the fine gauge wire (e.g., 24-gauge)
; interconnecting the shunted incandescent lamps was of
insufficient size to be adequately protected by normal
utility fuses in conventional 15- and 24-ampere branch circuits
wh~ch, in normal practice, supply AC power to such string
sets and other AC appliances connected at normal AC
receptacles,
A problem attendant to the use of the string set
disclosed and claimed in said Lehmann et al patent is that
tandem stringing of light sets was precluded. If a Christmas
tree or the like was desired to be strung with multiple string
sets, all of the plugs of each of the string sets had to be
connected at approximately the same location to a source of
power. ~se of such arrangement is extremely awkward, at
best, for the stringing of a large tree with lights since
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it is desirable if several strings are to be used that each
success.ive string be connected in tandem to the end of the
preceding string, i.e. so as to provide continuous end-to-end
stringing.
Another difficulty inherent in the Lehmann et al
construction was that the plural use of the light string sets,
all connected at the same loca~ion, to an AC utility service
provided no protection against the possibility that plural
stringing of lights might cause excessive use of current
such as to constitute a heavy electrical load.
Accordingly, among the several objects of the present
invention may be noted the provision of an improved light
string set; the provision of such a light string set
utilizing miniature incandescent lamps; the provision of
such a light string set permitting tandem stringing of lights
interconnecting individual light sets of the character-
described in end-to-end relationship; the provision of such
a light string set permitting the optimal use of fuse lamps
to provide short circuit protection of a series string of
incandescent lamps, a related obj~ct being the provision of
such a light string set permitting the use o~ series
interconnection of a plurality of miniature incandescsnt
lamps by relatively ~ine gauge wire. A related object is
the provision of such a light string set permitting tandem
stringing of successive light string sets even though fine
gauge wire is utilized to provide a series circuit
interconnection of incandescent lamps of each such string.
Another object of the invention is the provision of
a light string set which is fused to provide protection
against a short-circuit or excessive current flow into the
set, a related object being the provision of such a fused
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~8394
set which is of a universal conEiyuration amenable to alter-
native fusing embodiments as desired in ultimate configuration
so as to facilitate manufacturing.
Thus broadly, the invention contemplates a light string
set which comprises a plurality of lamp sockets for receiving
incandescent lamps with the sockets being carried by a flexible
wiring string exte~ding between a plug at one end of the
conductor string and a receptacle at the other e~d of the
conductor string, that receptacle is adapted to receive a plug
of a further light string set for tandem end-to-end connection
of plural light string sets, and the sockets include a first
end socket proximate the plug end of the conductor string and
a second end socket proximate the receptacle end of the con-
ductor string. ~ plurality of sockets are spaced at intervals
between the first and second end sockets, with the conductor
string comprising first conductor means interconnecting each
of the sockets in a series circuit, with the series circuit
extending from a terminal of the first end socket to a terminal
of the second socket. A second conductor means connects another
terminal of the first end socket to a first terminal of the
plug, a third conductor means connects another terminal of the
second end socket to a second terminal of the plug, a fourth
conductor means connects another terminal of the first end
socket to a first terminal of the receptacle, and a fifth
conductor means connects another terminal of the second end
socket to a second terminal of the recep-tacle. ~ fuse means
is associatèd with each of the first and second end sockets
for providing current overload protection.
In an alternative embodiment, the first conductor means
comprises insulated wire of a first relatively fine gauge having
limited current carrying ability, with the second, third, fourth
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and fifth conductor means comprising insulated wire of a gauge
substantially greater than the first gauge and having increased
current carrying capability.
Specifically, the firs-t means can be insulated wire
of less than 20-gauge, and the series circuit wiring together
the lamp sockets can be insulated wire segments each of less
than 20-gauge.
Other objects of the invention include the provision
of a light string set utilizing miniature lamps which are
easily changed in the event of lamp burnout; the provision
of such a light strlng set which is extremely attractive
and pleasing to the eye, producing a sparkling optical effect
from each lamp; and the provision of such light set which
is conducive to extremely economical manufacture through
the use of low cost materials and simplicity of construction.
Other objects will be in part apparent and in part
pointed ou' in the following description.
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In the drawings which illustrate embodiments of the
invention. . .
FIGURE 1 is a pictorial representation of a first
embodiment of light string set in accordance with the
invention, illustrating the form of certain lamp socket and
lamp reflector features with the reflector shown in cross-
section, and illustrating other portions thereof in the form
of an electrical circuit diagram.
FIGURE 2A iS an electrical circuit diagram of the
light set of FIGURE 1.
FIGURE 2B is an electrical circuit diagram of an
alternative embodiment having certain features of the light
set of FIGURE 1.
FIGURE 3A is a side elevational view of an incandescent
use lamp of a miniature nature used in the invention.
FIGURE 3B is a cross-section of a lamp socket for
receiving the incandescent lamp of 3A.
FIGURE 3C is a bottom elevational view of a lamp
holder receivable in the socket of FIGURE 3B.
FIGURE 4A is a side elevational view of a miniaturized
incandescent lamp which is used in the light string set of
FIGURE 1 with fuse lamps of the configuration shown in
FIGURE 3A.
FIGURE 4B is a cross-section view of a lamp socket
for receiving the incandescent lamp of FIGURE 4A.
FIGURE 4C is a bottom elevational view of a lamp
holder xeceivable in the socket of FIGURE ~B.
FIGURE 5A and 5B are cross-sections respectively,
of an incandescent fuse lamp bulb and shunted lamp bulb for
use in the lamp assembly of FIGURE 3A and FIGURE 4A~
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FIGURE 6 is a view in cross-section illustrating
a lamp of FIGURE 5 as mounted in a lamp holder to provide
an assembly as illustrated in FIGURE 3A or FIGURE 4A.
FIGURE 7 is a perspective view of a fuse holder of
the light set of FIGURE 1, a molded enclosure for the fuse
holder being depicted by phantom lines.
FIGURE 8 is another perspective view of the fuse
block but without fuses therein.
FIGURE 9 is a cartridge fuse of the type mounted
in the fuse block of FIGURE 8q
FIGURE 10 is a perspective view of a terminal assembly
for making electrical contact with such fuse in the fuse
holder of FIGURE 7.
Corresponding reference characters indicate
corresponding parts throughout the several views of the
drawings.
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Referring now to FIGURE 1, a first embodiment of
a new light string set of the present invention is indicated
in its entirety at 10. String set 10 comprises a plurality
of lamp sockets 11, 12a-12n, and 13, there being a convenient
number ~f lamp sockets such as fifty so that the total length
of the cord may be several tens of feet in length. As will
be explained, lamp sockets 11 and 13 are different from
lamp sockets 12a-12n. More specifically, lamp sockets 11
and 13 are specifically adapted to receive only a special
lamp holder. The lamp holder may contain a fuse-type
incandescent lamp or a shunt-type incandescent lamp, in
accordance with a desired em~odiment. For p~rposes of
illustration only, lamp socket 11 is shown as having a fuse
lamp 15 therein and lamp socket 13 is shown as having a
fu~e lamp 17 therein.
Each of the remaining lamp sockets 12a-12n contain
respective miniaturized shunt-type incandescent lamps 18a-18n.
As will become apparent, each of lamps 15, 17 and 18a-18n
is connected in a series circuit which is provided with
AC power by a conventional plug 20 having a pair of terminals 21
and 22, such power being supplied through a fuse holder 23
containing fuses 25, 26 tsee Fig. 2). The flexible insulated
wire conductors which interconnect lamp sockets 11, 12a-12n
and 13 are twisted together to provide a string of lights,
such string being several feet in length, as noted.
As will become apparent, a first embodiment of the
invention mades use of shunt-type incandescent lamps in all
of the soc~ets, while a second embodiment employs fuse lamps
in the end sockets 11, 13 and shunt-type lamps in the
remaining sockets 12a-12n.
39~
The string is terminated in a receptacle 27 having
a pair of recessed terminals 28, 29 (see Fig. 2) for
receiving the terminals o~ a plug, similar to plug 20 of
another string of lights, Accordingly, it will be understood
that successive light sets may be strung together end-to-
end in tandem fashion.
Each of lamp sockets 12a-12n is provided with a
respective reflector 31a-31n which is fitted over the
respective lamp socket for reflecting and refracting light
therefrom. The cross-section of reflector 31c is illustrative
of the detail. The reflectors are each of a molded
synthetic plastic material such as acrylic styrene of a
transparent nature having a relatively high index of refraction.
Such material is resilient.
More specifically, reflector 31c has a collar
portion 33c encircling the circumference of the exterior
surface 35c of the socket, such surface being approximately
cylindrical. Extending radially outward and upward from
collar 33c are a plurality of sections or segments 34c which
are each petal~form. These sections are arcuately spaced
around the lamp socket. Thus, light is not only reflected
upwardly and outwardly from each of the reflectors but is
transmitted through the acrylic material and passes through
the spaces between the petal-shaped segments as well. Hence,
the light is refracted greatly for causing a sparkling effect.
The end lamp sockets may also have such reflectors,
but it is presently preferred to omit them from the end
lamp sockets so that in constructing a light string set of
the second embodiment wherein fuse lamps are employed in
the end socketsr the user will readily be able to identify
the fuse lamp sockets which otherwise might beldifficult
to locate when embedded in the foliage of a tree decorated
with the set.
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394
Sockets 12a-12n constitute a first set of sockets
adapted to receive the miniature shunt type incandescent
lamps 18a-18n which are mounted in lamp holders. These
lamps each have a filament such as that shown at 37a and a
filament shunt 3ga consisting of wire interconnecting the
filament leads and permitting flow of current therethrough
if the filament should burn out. The end lamps 15 and 17
are each also of a shunted type having a filament such as
that designated at 41 having connected thereacross a shunt 42,
the shunt again being such as to permit flow of current
through the lamp if the ilament burns out.
Lamp socket 11, located at one end of the series
string, has a terminal 45 connected to one end of series
circuit 44. The other end socket 13 has a terminal 47
connected to the other end of series circuit 44. Each of
the connections between the terminals 45 and 47 making up
series circuit 44, which circuit extends from terminal to
terminal of each of sockets 12a-12n, is constituted by fine
gauge insulated wire (e.g. 24 gauge) to provide economy of
manufacture and low cost construction. Except for this fine
gauge wire interconnecting the several sockets of the string
set, the other conductors are of a heavier gauge flexible
insulated wire (e.g. 20 gauge).
Such heavier~gauge wire is used to provide a
connection having portions 49a and 49b connected through
fuse 25 to the first terminal 21 of plug 20. A third
connection comprising leads 51a and 51b connected through
~use 26 connects plug terminal 22 with the second terminal 52
of lamp socket 13. A fourth conductor 54 of this larger
gauge wire connects the same terminal 52 of lamp socket 13
with terminal 28 of receptacle 27. Finally, a fifth
conductor 55 of such heavier gauge wire interconnects
terminal 50 of lamp socket 11 with terminal 29 of receptacle 27.
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394
Accordingly, conductors 49a, 49b, 51a and 51b, 54 and 55provide increased cuxrent carrying capacity as compared with
the conductor arrangement 44 which interconnects the several
lamp sockets in series.
As i5 apparent from Figure 1, the conductors 49a,
49b and 51a, 51b which are connected through fuse holder 23
are twisted together. Similarly, conductors 54 portions
of conductor 51b,-and conductor 55 are twisted together
throughout the extent of the lamp socket interconnections
0 of the string set. Finally an end portion of the light
set comprising conductors 54 an~ 55 are twisted together,
terminating at receptacle 27.
Figure 2B illustrates an alternative embodiment of
the invention. This embodiment does not utilize a fuse
holder of the type shown in Figure 2A, but rather employs
fuse lamps 15' and 17', said fuse lamps being received in
receptacles 11 and 13 at the ends of the series string of
interconnected sockets. Said fuse lamps 15' and 17' each
has a filament 41' interconnected with the socket by means
of a lead-in conductor 56 of "Dumet" metal, such metal having
desired thermal expansion characteristics, filament 41' having
the characteristic of being fusible and reaching a temperature
causing melting thereof in the event of excessive current
flow through the filament 41' and conductor 56. Such fuse
lamps are constructed in accordance with the teaching of
my U. S. Patent No. 4,030,059, issued June 14, 1977.
Accordingly, there will be seen by reference to Figure 2B
that excessive current flowing the series circuit 44 consisting
of interconnected lamp sockets in the same wiring configuration
shown in Figure 2A, will cause the conductor portion 56 of
the respective fuse lamp 15', 17' to melt and thereby open
the circuit for protection thereof. Such excessive current
may result, for example, by the shorting together of
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conductors 44 and 51, as through abrasion thereof.
From the foregoing it will be seen that the circuit
configuration of Figure 2B provides protection against such
short circuit conditions or other cause for excessive current
flowing in the series circuit 44 in a manner different from
Figure l in that a fuse lamp will open-circuit to provide
such protection causing extinguishing of all lights in the
string, rather than through open circuit operation of one
of fuses 25, 26 of the fuse holder. Yet the existence of
a short circuit or other circuit overload condition causing
such fuse lamp or fuse, as the case may be, to open will
result in each case in all of the lights of the string set
becoming extinguished. Accordingly, the user will understand
that a short circuit condition has existed and may replace
a fuse lamp in the case of the circuit of Figure 2B and
attempt use again of the string set to ascertain whether
or not a short circuit is still present. If not, continued
operation of the strin~ set will be normal in all respects.
However, a continuing short circuit will once again cause
one of the fuse lamps 15', 17' to open. With either
embodiment, the user will thereby be alerted to the existence
of a short circuit or overload condition and may then
investlgate the same and correct the condition causing it
or take such remedial action as may be necessary to preclude
damage and to eliminate any hazardous condition.
Figures 3A-3C and 4A-4C compare the configurations
of the end lamp sockets with the other sockets and compare
the configurations of the preferred fuse lamp with the
shunt-type lamps.
Thus, Figure 3A shows a fuse lamp assembly comprising
one of the fuse lamps 15 secured to a lamp holder 57.
Similarly, Figure 4A illustrates one of the shunt-type
~lamps~-18a-secured--to a lamp holder 58 which is of a
--10--
39~
configuration different from holder 57. Together lamp 15
and holder 57 constitute a lamp assembly which can only be
received by one of the end sockets, e.g., socket 11, as
shown in cross-section in Figure 3B. Similarly, the shunt-
type lamp 18a and its lamp holder 58 together constitute a
lamp assembly which can be received only by a lamp socket such
as socket 12a shown in cross-section in Figure 4B.
In accordance with the first preferred embodiment,
the lamp holder 57 of the configuration to be received by
an end lamp socket 11 or 13 will hold a lamp of the same
type as holder 58.
Lamp assemblies as depicted in Figures 3A and 4A
are provided by inserting a fuse lamp such as designated
at 59 in Figure 5A or a shunt-type lamp such as that
designated at 59' in Figure SB into an appropriate lamp
holder 57 or 58.
Referring to Figure 5A, a fuse lamp of the presently
preferred second embodiment incorporates the teachings of
the above-identified U~ S. Patent No. 4,030,059 and a specific
descxiption is, therefore, not necessary except to indicate
generally that such lamp include a glass envelope 60 from
which a pair of electrodes 61, 62 extend from the rounded
bottom 63 of the glass envelope. The envelope is sealed
in conventional manner as indicated at 64 at the tip thereof.
Simil~rly, a shunt-type lamp, as depicted in Figure 5B,
contains a similar glass envelope 59' having electrodes 61',
62' extending from the bottom 63' thereof. The envelope
is similarly sealed as indicated at 64'. The lamp includes
a filament 66 and a conventional glass bead 67 for maintaining
filament leads in spaced apart relationship within the
evacuated glass envelope.
3g~
This shunt-type configuration of a miniaturized
incandescent lamp utilized in both embodiments is characterized
by a shunt 68 constituted by several turns of thin wire
such as of aluminum connected across the filament leads
just above bead 67. It will be understood that shunt 68
will continue to permit current to flow via electrodes 61',
62' in the event of opening of filament 66, as when the same
burns out.
Figure 6 is illustrative of either type of lamp
received within a representative lamp holder 70. Thus,
assuming the lamp is of the configuration shown in Figure 5A,
i.e., a fuse lamp 59, the wire leads or electrodes 61, 62
extend downward from the lower envelope portion 63 through
a pair of apertures 72, 73 provided in a tip portion 75
of the lamp holder.
The lamp holder also includes side walls 76 for
receiving the representative envelope portion 63 of lamp 59,
all as illustrated in Figure 6, the lamp being secured in
the lamp holder by distal portions of leads 61 and 62
being bent upward against surfaces at opposite sides of
tip portion 75 of the lamp holder. Accordingly, as bent
in the form illustrated in Figure 6, the leads 61, and 62 of
the lamp are presented for being contacted when the assembly
of Figure 6 is i~serted in a recess of an appropriate lamp
socket.
The external surface configuration of an end lamp
holder, such as that illustrated at 57, is different from
the exterior surface configuration of a lamp holder 58, as
illustrated in Figure 4A, for one of the remaining lamps.
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3'34
As shown in Figure 3B, an end lamp socket includes
a recess 7~ for receiving a corresponding side wall 77 of
the lamp holder 57. This recess is provided on opposite
sides with a pair of grooves 80, 81 which receive corresponding
beads 83, 84 or lamp holder 57. Recess 78 also includes
flats 79, 79' disposed at opposite sides of the recess,
there being corresponding flats such as designated at 77, 77'
on the side walls of the lamp holder 57. The tip portion
of lamp holder 57 is designated 85 and is of rectangular cross
section so as to be received within a recess 86 of lamp
socket 11.
The cross section of rectangular socket recess 86 and
corresponding cross section of tip 85 of the lamp holder
(Figure 3C) is smaller in cross section than recess 78 which
receives side wall portions 77, 77' of the lamp holder. A
pair of terminals 87, 88 are fitted at opposite sides of
recess 86 of the lamp socket, such terminals being crimped to
corresponding leads 90, 91 to provide the connections for
the two terminals of the lamp socket. Such crimps are
illustrated at 92, 93. Accordingly, it may ~e seen that
distal portions 95, 96 may contact tne surfaces of the
respective electrodes 87, 88 of the lamp socket. Such
electrode distal portions g5, 96 extend through corresponding
apertures 98, 9g in the ~ottom surface of the lamp holder.
The shunt-type incandescent lamp holder 12a includes
a corresponding recess 101 having side walls 103 of cylindrical
shape for receiving cylindrical form side walls 104 of lamp
holder 58. Such lamp holder also includes a rectangular tip
portion 106 of the same form as lamp holder 58 which tip
portion is received within a deeper recess 107 of lamp
socket 12a having rectangular cross section. Again, distal
portions 109, 110 of the lamp leads extend downward through
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394
corresponding apertures 112, 113 in the bottom surface of the
lamp holder and are bent upward as shown in Figure 4A for
presentment for contact by electrodes 115, 116 which are
crimped to respective leads 118, 119, the latter extending
upward into the shunted lamp socket 12a and being secured
to the electrodes by crimping, as illustrated at 121, 122.
Because of the flats 79, 79' of each of the end lamp
sockets, the lamp holder for each of the remaining lamps, i.e.,
each being of the configuration shown in Figure 4A, is
precluded from being received within recess 78 of an end
lamp socket. Correspondingly, the beads 83, 84 of each
of the lamp holders suited for being received by an end lamp
socket precludes insertion of a lamp assembly for the end
lamps into one of the remaining sockets (i.e., of the
configuration shown in Figure 4B).
Each of the lamp holders and lamp sockets is
preferably of a molded synthetic resin material for purposes
of economy and ease of manufacture.
Figures 7-10 illustrate the details of the fuse
holder 23 suited for use in the first embodiment.
Said fuse holder 23 comprises a molded plastic fuse
block 121 having a pair of oppositely disposed channels 123,
124 for receiving a pair of cartridge fuses 126 shown in
Figure 9. More specifically, ~he fuse block 121 in cross-
section is of I-beam configuration, the channels 123, 124
being of cross-section corresponding to the cylindrical
terminal portions 127, 128 of fuse 126. Electrodes 130,
being arcuately formed as indicated at 130 in Figure 10,
are fitted over the terminals 127, 128 of the fuse and crimped
to conductors 49a and 49b and 51a, 51b as apparent from
Figure 7. Each fuse electrode is crimped to its corresponding
conductor, as indicated at 131 in Figure 10. With a pair of
electrodes as shown in Figure 10 secured to each end of
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3g4
the fuse, the fuse is then pressed into the corresponding
one of channels 123, 124 and secured therein by the encircling
relationship of the fuse block. A body 132 of molded
synthetic resin material is then placed around the fuse
block for securing the assembly as depicted in Figure 7.
In operation, a new light set of the invention
provides not only the advantage of utilizing a fine gauge
wire for providing a series circuit and thereby permitting
the use of low cost materials, but also provides assurance
against the possibility of an overload in such series
circuit by virtue of the fuse lamps 15, 17 at the opposite
ends of the series connected plurality of miniature
incandescent lamps. In addition the con~iguration permits
tandem stringing of plural sets by simply connecting an
additional set at the receptacle 27. In the first embodiment,
the fuse holder 23 with its fuses 25, 26 provides protection
against a short circuit, the possibility of overload from
excessive stringing of tandem sets. In the second embodiment,
each fuse lamp 15', 17' of a light string set protects that
set from current overload conditions.
It will be apparent from the description that the
first embodiment makes use of end lamp sockets which are
of construction different from the remaining sockets of the
series string. While aIl of the sockets utilized in the
first embodiment may be of identical configuration, the
construction described and shown herein makes possible fox
identical wiring of sockets and socket configurations to
be employed in both embodiments. Hence, the described
embodiments make possible a high degree of manufacturing
economy in that either embodiment may be constructed from
the same component parts and wiring assemblies. Thus, if
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394
it is desired to manufacture light string sets of the second
embodiment, the preferred socket configurations described in
connection with the first embodiment may be utilized, the
only difference being that a fuse lamp holder of the type
described in connection with the first embodiment is not
employed. Such fuse holder may not be necessary for some
intended usages of a light string set, and it may be instead
preferred to utilize fuse lamps as shown in connection with
said second embodiment. Hence, the constructions shown and
described conduce to manufacturing economy and achieve in
effect a universal wiring and socket configuration.
In view of the foregoing it will be see~ that the
several objects of the invention and other advantages are
achieved by the new constructions which have been described.
Although the foregoing includes the description of
the best de of the embodiments contemplated carrying out
the invention, various modifications are contemplated.
As ~arious modifications could be made in the
constructions herein described and illustrated without
departing from the scope of the invention, it is intended
that all matter contained in the foregoing description or
shown in the accompanying drawings shall be interpreted as
- illustrative rather than limiting.
.
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