Information
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Patent Grant
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6361185
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Patent Number
6,361,185
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Date Filed
Wednesday, July 12, 200024 years ago
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Date Issued
Tuesday, March 26, 200222 years ago
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Inventors
-
-
Examiners
Agents
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CPC
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US Classifications
Field of Search
US
- 362 249
- 362 252
- 362 123
- 362 806
- 362 227
- 315 185 S
- 315 59
- 315 185 R
- 315 210
- 315 58
- 337 290
- 337 292
- 337 293
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International Classifications
- F21V2114
- A47G3316
- H01H8554
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Abstract
A safety structure to prevent a socket from being over-heated in a lamp string, which comprises a separate lamp string made of a pre-determined number of sockets connected in series. The power-supply wire of the lamp string is connected in series with an additional socket to be plugged with a protective bulb. Two copper wires mounted in the glass tube of the protective bulb are fixed in place by means of a positioning bead. The tail ends of the two copper wires are connected with a fuse having a pre-determined power dissipation. In case of the fuse in the protective bulb being over-loaded, the fuse will be burned out automatically so as to prevent the sockets from being over heated to cause a hazard.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a Christmas lamp string, and particularly to a safety structure to prevent a socket from being over-heated in a lamp string.
2. Description of the Prior Art
The conventional Christmas lamp string is usually made of an elongate lamp string, which includes a plurality of separate lamp strings connected together; each separate lamp string includes a plurality of short power-supply wires connected between two sockets. The first bulb of the lamp string is connected, by using a longer wire, with the plug; the longer wire is twisted with the lamp string to form into a separate lamp string.
Each of the sockets in the lamp string is to be plugged with a connector, which is mounted with a bulb so as to facilitate the bulb to be replaced in case of being burned out. The number of sockets and the coefficient of resistance of each bulb are all pre-designed in accordance with the voltage and current of a given area.
The plug of each lamp string is furnished with a fuse to prevent the power-supply wire of the lamp string from being over-loaded. In case of the power-supply wire having a short circuit or being over-loaded, the fuse in the plug will be burned out automatically so as to avoid a hazard; however, the fuse furnished in the plug is not designed to prevent the socket from being overloaded.
The bulb plugged in the socket of each lamp string has two copper wires to be fixed in place with a positioning bead; the tail ends of the copper wires are mounted with a tungsten filament; the aforesaid parts are then mounted in a glass tube, of which both ends are to be sealed by means of different welding methods respectively so as to form into a bulb; the bulb is to be plugged in the socket of the lamp string. Since the sockets of the lamp string are connected one another in series, the whole lamp string is subject to having an open circuit and outage in the event of a tungsten filament being burned out.
In order to avoid the lamp string to turn off upon the tungsten filament of a bulb being burned out, an aluminum fuse of 0.065 m/m is wound around the two copper wires near the positioning bead; the number of turns of the fuse is designed in accordance with technical requirement, but it has at least 2.5 turns to enable the fuse to mount in place. The object of furnishing such a fuse is to maintain the whole lamp string to be in lighting-up condition in case of the tungsten filament being burned out; in that case, the fuse having lower resistance can still have the two copper wires maintained in conduction condition. The requirement of at least 2.5 turns of the aluminum fuse is to prevent the fuse from being burned out upon the current being not over a given value.
The aluminum fuse mounted between the two copper wires and near the positioning bead must have a resistance less than that of the tungsten; in case of the tungsten filament being burned out, the aluminum fuse can still maintain a current to flow through the two copper wires so as to avoid the lamp string to have an outage for a short time; however, since every bulb in the lamp string will lose at least a portion of the tungsten filament to share the power dissipation, the tungsten filaments of the rest bulbs will have a higher power dissipation; in other words, the serviceable life of the tungsten filament in the bulb will be reduced proportionally. Whenever the number of bulbs in a lamp string is reduced gradually, the bulb number of bulbs, which are not lit up, will be increased. Since the power dissipation of every bulb is increased, the temperature thereof will also be increased; then, the temperature of the connector of each bulb will be increased to an over-loaded condition. Generally, the material used for making the connector and the socket will be improved to withstand a given high temperature; in that case, the cost for the material thereof will be increased without solving the problem of a single bulb in a lamp string to suffer from a high temperature.
SUMMARY OF THE INVENTION
The prime object of the present invention is to provide a lamp string, in which a plurality of sockets are connected in series; the first socket and the last socket are connected with the plug by means of separate power-supply wires respectively; a socket for a protective bulb is connected in series between the first socket and the plug; the tail ends of the two copper wires of the protective bulb are mounted with a fuse; in case of the tungsten filament of a bulb in the lamp string being burned out, the tungsten filaments of the rest bulbs will be overloaded with power than the value pre-designed; then, the fuse in the protective bulb will be burned out soon to cause an open circuit so as to prevent the tungsten filaments of the bulbs from being over-loaded to cause a high temperature.
Another object of the present invention is to provide a safety structure, in which a protective bulb is plugged in the socket of the lamp string; the tail ends of the copper wires in the protective bulb are mounted with a fuse, which can be mounted in place directly by means of an assembling machine without requiring additional machine for the protective bulb.
Still another object of the present invention is to provide a safety structure, in which the protective bulb plugged in the lamp string may be designed into a shape to be the same as that of the ornamental bulb, or a cylindrical shape so as to facilitate to identify it.
A further object of the present invention is to provide a safety structure, in which the protective bulb can be plugged into a connector as that of an ornamental bulb, and then the connector can be plugged into the first socket of the lamp string.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a plan view of a conventional lamp string connected in series.
FIG. 2
is a sectional view of a bulb of the ornamental lamp.
FIG. 3
is a sectional view of a bulb with a fuse according to the present invention.
FIG. 4
is a plan view of the present invention, showing a plurality of bulbs with fuses connected in series.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to
FIGS. 1 and 2
, every separate lamp string
13
is made of a plurality of short power-supply wires
14
C to connect with a plurality of sockets
15
in series, i.e., the first socket
15
A is connected with a power-supply wire
14
A to the plug
18
, and the last socket
15
B is connected with the plug
18
through a power-supply wire
14
B; then, the two power-supply wires (
14
A+
14
C,
14
B) are twisted together to form into one lamp string
13
. All the sockets
15
of the lamp string
13
are plugged with bulbs
17
respectively via connectors
16
so as to form into a lamp string
13
.
The bulb
17
in the lamp string
13
is substantially a bulb used in a conventional lamp string
13
of the ornamental lamp
11
. The tail ends of the two copper wires
25
are fixed in place with a positioning bead
24
before mounting a tungsten filament
27
. Beside and near he positioning bead
24
, at least 2.5 turns of fuse
26
made of aluminum with a diameter of 0.065 m/m are wound around the two copper wires
25
. The tail ends of the two copper wires
25
are connected with a tungsten filament
27
having a given resistance; then, the two copper wires
25
fixed in place with the positioning bead
24
are mounted in a glass tube
21
and the two copper wires
25
are connected and sealed together by means of a welding method to form into a round sealed part
22
; the other end of the glass tube
21
is also sealed with the same welding method to form into a tapered sealed port
23
.
The bulb
17
including two copper wires
25
, a fuse
26
made of aluminum and a tungsten filament
27
is plugged into a socket
15
of the lamp string
13
.
In case of the tungsten filament
27
of one bulb
17
in the lamp string
13
being burned out, the current can also flow through the aluminum fuse
26
wound around the two copper wires
25
. Since the coefficient of resistance of the tungsten filament
27
of a bulb
17
in the separate lamp string
13
has been designed regularly, the resistance of the separate lamp string
13
will be reduced upon the tungsten filament
27
of a bulb
17
being burned out; then, the power dissipation of every bulb
17
will be increased to result a higher temperature therein. In case of the tungsten filaments
27
of several bulbs
17
in a lamp string
13
being burned out, the rest bulbs
17
can continue to be lit up; however, the power dissipation of each bulb
17
will be increased to a temperature which would cause the connector
16
to be unable to withstand the high temperature; in that case, a danger might take place.
As shown in
FIGS. 3 and 4
, the power-supply wire of the lamp string
13
is connected in series with an additional socket
15
C, in which a protective bulb
19
is mounted; the protective bulb
19
is substantially a bulb
17
of the conventional ornamental lamp
11
except for the tail ends of the two copper wires
25
being mounted with a fuse
28
instead of a tungsten filament
27
. In the protective bulb
19
, the two copper wires
25
and the positioning bead
24
are connected together first, and then a fuse
28
is mounted on the tail ends of the two copper wires
25
before being put in he glass tube
21
and being welded in place to form into a round sealed port
22
at one end thereof; the other end thereof is closed into a tapered sealed port
23
or other suitable shape. After the protective bulb
19
and the connector
16
are assembled together, the connector can be plugged in any one of the sockets
15
. In case of the tungsten filament
27
of any bulb
17
in the lamp string
13
being burned out, the resistance of the lamp string
13
will be reduced to cause every bulb
17
to have higher power dissipation. The protective bulb
19
plugged in the lamp string
13
can also sense the increased power dissipation of every socket
15
; the fuse
28
of the protective bulb
19
is pre-designed with a given figure of power dissipation; in case of the tungsten filaments
27
of a given number of bulbs
17
in the lamp string
13
being burned out, and reaching a given pre-determined number (such as over three bulbs
17
being burned out), the fuse
28
of the protective bulb
19
would be burned out, and the lamp string
13
will have an open circuit so as to prevent from damaging the socket
15
because of a single bulb
17
to have a high temperature, i.e., to overcome the problem of a bulb of the lamp string to be over-heated.
Claims
- 1. A safety lamp string comprising:a) an electrical plug; b) a first power supply wire extending from the plug; c) a plurality of lamp sockets connected in series to the first power supply wire including a first lamp socket and a last lamp socket, the first lamp socket being located closest to the electrical plug of the plurality of lamp sockets; d) a second power supply wire extending directly between the electrical plug and the last lamp socket; e) a single protective bulb socket connected solely to the first power supply wire between the electrical plug and the first lamp socket; and, f) a protective bulb located in the protective bulb socket and comprising: two wires having ends located within the protective bulb with a glass bead maintaining the two wires spaced apart from each other; and a fuse connected between the ends of the spaced apart wires, whereby the fuse protects against overloading and over heating of bulbs located in the plurality of lamp sockets.
US Referenced Citations (7)