Patent Publication Number: US-6713971-B1

Title: Lamp string with an open-circuit-proof structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a Christmas lamp, and particularly to a lamp string with an open-circuit-proof structure. 
     2. Description of the Prior Art 
     In a conventional Christmas lamp string, a plurality of separate lamp strings is connected in series into a long lamp string; in the separate lamp string, a power-supply wire having a suitable length is used to connect between two lamp assemblies in series; the first lamp assembly and the last lamp assembly are connected with different length of two power-supply wires to a plug; then, the whole lamp assemblies and the power-supply wires are twisted into a separate lamp string. 
     Each lamp assembly in one lamp string includes a socket, a bulb receptacle, and a bulb. In order to facilitate removing or replacement of a bulb, the bulb is usually mounted in a bulb receptacle, and then the bulb receptacle is plugged into the rectangular cavity of a socket. The number of lamp assemblies and the resistance of each lamp assembly are designed in advance in accordance with the voltage and current values of a local area. 
     In order to prevent the power-supply wire from being overloaded, or from having a short-circuit to cause a danger, the socket of each lamp string must be furnished with a fuse wire; however, the fuse wire in the socket is not designed in accordance with the overload value of the lamp assembly. 
     Each bulb of every lamp assembly has a glass positioning bead welded around two parallel magnesium-plating filaments; the short section of two filaments at one end of the positioning bead is connected with a tungsten filament, while the other end of the positioning bead has two longer filaments pulled out of the bulb sealed; the magnesium-plating filaments are plugged into the center hole of the bulb receptacle, and then the two filaments are bent and attached along two planes on both sides of the bulb receptacle respectively; after the bulb receptacle is plugged into the center hole of the socket, the filaments on both sides of the bulb receptacle will be in contact with the contact copper plates of the power-supply wires respectively; in such a lamp string, if the tungsten filament of only one bulb is burned out or one bulb is lost, the whole lamp string will be turned off because of the circuit is opened. 
     In order to prevent the aforesaid open circuit from taking place, a fuse made of aluminum of 0.065 m/m is wound around the two filaments on the outer end of the positioning bead before the tungsten filament being mounted on the tail ends of the two filaments; the number of turns of the fuse wire is at least 2.5 turns so as to enable the aluminum fuse fastened in place. The purpose of furnishing the aluminum fuse is to prevent the lamp string from suffering an open circuit in case of the tungsten filament in a bulb being burned out, i.e., the low resistance fuse will maintain the two bulb filaments in a conduction state to keep the whole lamp string in lighting-up condition. 
     When one bulb in the lamp string is lost, a new bulb must be mounted therein; in case of no such bulb being available, the replacement has to be abandoned. 
     SUMMARY OF THE INVENTION 
     The prime object of the present invention is to provide a lamp string with an open-circuit-proof structure, in which each lamp assembly in a lamp string has a center hole; the center is furnished with rectangular cavity for mounting a fuse assembly; the outer rectangular cavity in the center hole is used for mounting a bulb receptacle with a bulb; since the socket is furnished with a fuse assembly, the whole lamp string will always be maintained in lighting-up condition in case of the tungsten filament of a bulb in the lamp string being burned out, or one of the bulb receptacle of the socket being lost because of the power-supply circuit being maintained in conduction condition by means of the fuse assembly. 
     Another object of the present invention is to provide a lamp string with an open-circuit-proof structure, in which the fuse assembly mounted in the center hole of the socket includes a fuse member and a fastening member; the fuse member has a positioning bead, which is used for fastening the two parallel magnesium-plating filaments in place; the short section of the two magnesium-plating filaments is wound with a fuse made of aluminum, while the longer section of the two magnesium-plating filaments extend the through slots of the fastening member; then, the tail ends thereof are bent and attached to the two planes respectively. The two bent magnesium-plating filaments of the fuse assembly are in contact with the contact copper plates respectively; in case of the bulb receptacle being lost or the tungsten filament of a bulb being burned out, the power supply of the lamp assembly can still maintained in conduction condition through the magnesium-plating filaments of the fuse assembly. 
     Still another object of the present invention is to provide a lamp string with an open-circuit-proof structure, in which a rectangular cavity is furnished under a rectangular cavity to mount the bulb receptacle, and it is used for mounting a fuse assembly; such fuse assembly would not hinder the bulb receptacle to plug in place. 
     A further object of the present invention is to provide a lamp string with an open-circuit-proof structure, in which a fuse assembly is mounted in the center hole of the socket; the tail ends of the two magnesium-plating filaments are mounted with tungsten filament directly without winding aluminum fuse wire around the two magnesium-plating filaments. 
     A still further object of the present invention is to provide a lamp string with an open-circuit-proof structure, in which the center of the fastening member in the fuse assembly has a recess, under which two through slots are furnished on both sides thereof; the two through slots are used to have the two longer section of magnesium-plating filaments passed through; the tail ends of the magnesium-plating filaments are bent and attached to the planes respectively; the recess in the center thereof is used for mounting the positioning bead so as to prevent the fuse member from moving unintentionally as a result of shaking. 
     Yet another object of the present invention is to provide a lamp string with an open-circuit-proof structure, in which the longer section of the two magnesium-plating filaments at one end of the positioning bead is wound with aluminum fuse wire of 0.065 m/m at least 2.5 turns; normally, the aluminum fuse wire would not hinder the current flowing in the tungsten filament of the bulb; in case of the tungsten filament of a bulb being burned out or a bulb receptacle being lost, the low resistance aluminum fuse wire will maintain the power supply in a closed circuit condition and the whole lamp string will still be in lighting up condition. 
     Yet still another object of the present invention is to provide a lamp string with an open-circuit-proof structure, in which the fastening member of the fuse assembly is substantially a rectangular block to be plugged in a rectangular cavity of the socket; the magnesium-plating filaments on both sides thereof are in close contact with two contact copper plates respectively. 
     Yet a further object of the present invention is to provide a lamp string with an open-circuit-proof structure, in which the fastening member of the fuse assembly is a rectangular block, of which the lower part has a rod; both sides of the rod are designed to fit to the power wire groove; after the fuse assembly is plugged in place, the rod will fill in the power wire groove between the two power-supply wires so as to prevent rain water from flowing into the rectangular cavity of the socket. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of the present invention, showing the connection structure of a lamp string. 
     FIG. 2 is a disassembled view of the present invention, showing the relation among the assemblies of the first embodiment. 
     FIG. 3 is a fragmental section view of the present invention, showing a fuse assembly plugged into the socket. 
     FIG. 4 is a sectional view of the present invention, showing a fuse assembly plugged in the hollow space of the socket. 
     FIG. 5 is a disassembled view of the present invention, showing the relation among the assemblies of the second embodiment. 
     FIG. 6 is a fragmental section view of the present invention, showing a fuse assembly plugged into the socket. 
     FIG. 7 is a sectional view of the present invention, showing a fuse assembly plugged in the hollow space of the socket. 
     FIG. 8 is a sectional view of the present invention, showing the second method of winding the fuse wire in the first embodiment. 
     FIG. 9 is a sectional view of the present invention, showing the third method of winding the fuse wire in the first embodiment. 
     FIG. 10 is a sectional view of the present invention, showing the second method of winding the fuse wire in the second embodiment. 
     FIG. 11 is a sectional view of the present invention, showing the third method of winding the fuse wire in the second embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 3, the lamp string with an open-circuit-proof structure according to the present invention is a new structure, in which the lamp assemblies  12  are connected in series by means of short power-supply wires, and the first lamp assembly  12 A and the last lamp assembly  12 B are connected to the plug  13  by means of power-supply wires  14 A and  14 B respectively. The lamp assemblies  12  are twisted and connected in series to form into a lamp string  11 . In the lamp string  11 , every socket  18  includes a rectangular cavity  45  for receiving a fuse assembly  16 . In case of the tungsten filament  47  of a bulb being burned out or a bulb receptacle  17  of a socket  18  being lost, the power supply of the whole lamp string is still maintained in the normal lighting-up condition because of the fuse assembly  16  able to back stop the aforesaid burning out. 
     As shown in FIGS. 2 to  4 , each lamp assembly  12  in the lamp string  11  includes a socket  18 , a fuse assembly  16 , a bulb receptacle  17 , and two contact copper plates  21  and  22  connected with power-supply wires  19  and  20 ; the bulb  15  in the aforesaid lamp string is a bulb used in a conventional lamp string. The bulb  15  has two parallel magnesium-plating filaments  24  to be fixed in place with a positioning bead  25  before the tungsten filament  47  being mounted on the tail ends of the two magnesium-plating filaments  24 ; the two magnesium-plating filaments  24  are fixed in a glass tube  23  at a given length; one end of the glass tube  23  is sealed together with the two magnesium-plating filaments  24  by means of a round welding method, i.e., one end of the glass tube is sealed with a round seal, while the other end thereof is a point-shaped seal. 
     Two longer magnesium-plating filaments  49  out of the round seal of the bulb  15  are plugged through the center hole of the bulb receptacle  17 , and then extend under the rectangular block  27  of the bulb base  17 , and further extend along the guide grooves and the bevel surfaces  28  to the two planes  29  respectively; after the bulb receptacle  17  with a bulb  15  is plugged into the plug-connection cavity  41  of the socket  18 , the magnesium-plating filaments  49  on both sides of the bulb receptacle  17  will be in contact with the two contact copper plates  21  in the socket  18  respectively to form into a circuit in series. 
     The center cavity of the socket  18  in each lamp assembly  12  is used for receiving a plug-connection cavity  41 , a rectangular cavity  43 , a rectangular cavity  45  for plugging the fuse assembly  16 , a power wire groove  46  of power-supply wires  19  and a copper plate groove  40  of the contact copper plates  21 ; the power wire groove  46  in the socket  18  is also used to have the power-supply wires  19  and  20  riveted with two contact copper plates  21  and  22  respectively passed through. The two contact copper plates  21  and  22  are plugged and fixed in the copper plate grooves  40  on both sides of the rectangular cavities  43  and  45  respectively; then, the two power-supply wires  19  and  20  are connected to the socket  18  of next lamp assembly  12 . The plug-connection cavity  41  and the rectangular cavity  43  in the upper part of the center cavity of the socket  18  are used for plugging the bulb receptacle  17  of the bulb  15 . The two contact copper plates  21  and  22  on both sides of the rectangular cavity  43  are in close contact with the magnesium-plating filaments  49  respectively to form into an electric circuit. After the rectangular block  27  of the bulb receptacle  17  is plugged into the rectangular cavity  43  of the socket  18 , the bulb receptacle  17  would not rotate unintentionally. 
     Referring to FIG. 2, there is a rectangular cavity  45  under the rectangular cavity  43 , and it is used for plugging a fuse assembly  16 . Above the rectangular cavity  45 , there is a small plane  44  to partition the two rectangular cavities  43  and  45  clearly. The panels of the two rectangular cavities  43  and  44  are partitioned by means of a small plane  44 , and they can also be designed into a single plane so as to mount a fuse assembly on the lower portion thereof, and to mount a bulb receptacle  17  on the upper portion thereof. 
     The fuse assembly  16  plugged in the rectangular cavity  45  of the socket  18  includes a fastening member  30 , and a fuse member  36 ; the fuse member  36  is plugged in the fastening member  30 , which is to be plugged in the rectangular cavity  45  of the socket  18 . The magnesium-plating filaments  48  on both sides of the planes  34  of the fastening member  30  are to be contact with the two contact copper plates  21  and  22  respectively on both sides of the rectangular cavity  45  to form into an electric circuit so as to prevent from open circuit in the lamp string. 
     The fastening member  30  of the fuse assembly  16  is a rectangular member, which is furnished with two symmetrical slots  32  and  33  between the upper and lower planes thereof; a recess  33  is furnished between the upper plane of the two slots  32  and  33 . The upper ends of the two slots  32  and  33  are almost covered by the recess  31 . The two slots  32  and  33  and the recess  31  form into a space so as to enable the two parallel magnesium-plating filaments  49  of the fuse member  36  to extend from the upper part of the recess  31  and along the two slots  32  and  33  to the other end thereof. The positioning bead  37  of the fuse member  36  is mounted in the recess  31 , and the two magnesium-plating filaments  48  are bent along the two planes  34  of both sides thereof. 
     The planes of the rectangular fastening member  30  is designed to fit to the planes of the rectangular cavity  45  in the socket  18 ; particularly, the two wider planes  50  of the fastening member  30  are furnished with a suitable tapered plane so as to facilitate the plane  34  to plug in; as soon as the fastening member is plugged tight in place, the fuse assembly  16  will be mounted firmly in the rectangular cavity  45  of the socket  18 ; then, the magnesium-plating filaments  48  bent along the two planes  34  are in contact with the two contact copper plates  21  and  22  respectively. 
     As shown in FIGS. 2 to  4 , the fastening member  30  of the fuse assembly  16  is a rectangular member to be plugged into the rectangular cavity  45  of the socket  18 . As shown in FIGS. 5 to  7 , the fastening member  30  has a rod  51  extended downwards; the rod  51  is designed to fit to the shape of the power wire groove  46  in the lower part of the socket  18 ; the rod  51  is inserted into the rectangular cavity  45  first, and then press it into the power wire groove  46 ; the fastening member  30  with a rod  51  is quite easy to assemble in place than a fastening member without rod. 
     The fuse member  36  of the fuse assembly  16  includes two parallel magnesium-plating filaments  38 , a positioning bead  37  and a fuse wire  39 ; the design and making of the positioning bead  37  are the same as that of the positioning bead  25  in the bulb  15 , i.e., a positioning bead  37  is furnished and welded around the two parallel magnesium-plating filaments  38  so as to have the filaments  38  partitioned into a short magnesium-plating filaments  49  section and a long magnesium-plating filament  48  section. Between the two short magnesium-plating filaments  49 , wind 2.5 turns of an aluminum fuse  39  of 0.065 m/m; the aluminum fuse  39  is assembled together with the fuse member  36  and the fastening member  30 , and then is mounted in he rectangular cavity  45  of the socket  18 . Normally, the fuse wire  39  would not affect the current flowing in the tungsten filament  47  of the bulb  15 ; in case of the tungsten filament  47  of a bulb is burned out or the bulb receptacle being lost, the fuse wire  39  with low resistance will be used as a conductor. 
     After the fuse member  36  is mounted into the recess  31  of the fastening member  30 , the two long magnesium-plating filaments  48  on the other end of the positioning bead  37  will extend through two parallel slots  32  and  33  of the fastening member  30  and to the lower part thereof; then, they are bent and attached along the two planes  34 ; the positioning bead  37  of the fuse member  36  is confined in the recess  31  of the fastening member  30 ; in that case, the fuse wire  39  wound around the two magnesium-plating filaments  49  will be confined it a fixed position without moving unintentionally. 
     Before the fuse assembly  16  and the socket  18  being assembled together, two contact copper plates  21  and  22  should be mounted in the copper plate grooves  40  on both sides of the two rectangular cavities  43  and  45 , and then pull the two power-supply wires  19  and  20  out of the socket. When the fuse assembly  16  is mounted in the rectangular cavity  45 , the wider planes  50  thereof should be in contact with the rectangular cavity  45 ; then, the two magnesium-plating filaments  48  on both planes  34  will be in close contact with the two contact copper plates  21  and  22  respectively; then, the fuse assembly  16  is deemed mounted in place. When the fuse assembly  16  is a separate rectangular member, it should be held with a pair of tweezers to put in the opening end of the rectangular cavity  45  before being pushed in place with a push rod. If the lower part of the fuse assembly  16  has a rod  51  under the fastening member  30 , the fastening member  30  can easily be inserted into the rectangular cavity  45  of the socket  18 , and then use a push rod to push inwards; the rod  51  can provide a seal and filling function between the two power supply wires  19  and  20  so as to prevent rain water from flowing in. 
     The rectangular cavity  43  of the socket  18  is used for mounting the fuse assembly  16 , while the rectangular cavity  45  and the plug-connection cavity  41  above the fuse assembly  16  are used for mounting the bulb receptacle  17 ; the round tube  26  of the bulb receptacle  17  is to be plugged into the plug-connection cavity  41 , while the rectangular block  27  is to be plugged into the rectangular cavity  43 . After the bulb receptacle  17  is plugged into the rectangular cavity  43  of the socket  18 , the two magnesium-plating filaments  49  on the planes  29  will be in contact with the two contact copper plates  21  and  22  respectively to form into an electric circuit. 
     The bulb receptacle  17  is to be mounted into the plug-connection cavity  41  and the rectangular cavity  43 , which is designed to have a given height. The fuse assembly  16  is mounted into the lower part of the rectangular cavity  45  first, and then the bulb receptacle  17  is plugged into the rectangular cavity  45 ; then, the magnesium-plating filaments of the fuse assembly  16  and the bulb receptacle  17  will be in contact with the two contact copper plates  21  and  22  respectively; a short space is designed between the two aforesaid assemblies so as to prevent them from collision. 
     Every socket  18  of the lamp assembly  12  in the lamp string  11  is mounted with a fuse assembly  16 ; the tail ends of the two magnesium-plating filaments  24  of the bulb  15  are mounted with a tungsten filament  47 ; when a lamp string  11  is mounted in a place, it would not have an open circuit in case of the tungsten filament  47  of a bulb  15  being burned out, or a bulb receptacle  17  being lost; in other words, the lamp string is always maintained in lighting-up condition. 
     In the aforesaid fuse member  36  of the fuse assembly  16 , fuse wire  39  is wound around the two short section of magnesium-plating filaments  49  at one end of the positioning bead  37 . As shown in FIGS. 8 and 10, two different embodiments are shown, and the recess  31  of the fastening member  30  thereof has a communicating groove  53  which is used for laying the two long magnesium-playing filaments  48  of the fuse assembly  36 ; the tail ends of the filaments are bent and attached to the two planes  34 . The two longer sections of the magnesium-plating filaments are wound around with a fuse wire  54  nearing the positioning bead  37 . When the two long magnesium-plating filaments  48  of the fastening member  30  are laid through the two slots  32  and  33  respectively without affecting the fuse wire  54  fastened on the two magnesium-plating filaments  48 . 
     Referring to FIGS. 9 and 11, the fastening member  30  of the fuse assembly  16  has two through slots  32  and  33 , above which there is a communicating groove  56  with a curved surface between the two through slots  32  and  33 ; a fuse wire  57  made of aluminum is bent into U-shape, and is plugged into the two through slots  32  and  33 . The tail ends of fuse wire  57  are bent and attached to the planes  34  on both sides thereof. After the fuse assembly  16  is mounted in the rectangular cavity  45  of the socket  18 , the two fuse wires  57  laid along both sides of the fastening member  30  will be in close contact with the two contact copper plates  21  and  22  respectively. After the fuse assembly  16  is mounted into the rectangular cavity  45  of the socket  18 , it will provide a low resistance electric circuit between the two power-supply wires  19  and  20 . Normally, the current can flow through the bulb  15 ; in case of the tungsten filament  47  of a bulb  15  being burned out, or a bulb receptacle  17  of the socket  18  being lost, the whole lamp string can still maintain in lighting-up condition. 
     According to the description of the aforesaid embodiments, the features and structure of the present invention have been disclosed completely; it is apparent that the present invention has provide an obvious improvement, which is never anticipated and achieved by any person in the field; therefore, the structure of the present invention is deemed unique.