Patent Publication Number: US-2011050081-A1

Title: Lamp structure of dual-wire lighting string

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention generally relates to a lighting string, and more particularly to the structure of lamps that are connected to and powered by two electrical wires to make a lighting string. 
     DESCRIPTION OF THE PRIOR ART 
       FIG. 1  of the attached drawings shows the arrangement of a lamp and a power cord of a conventional dual-wire lighting string. The lamp, which is designated at  10 , comprises an illuminator  11 , a base  12 , and a socket  13 . The illuminator  11  comprises a light-emitting diode (LED) having two terminal pins  111  and is mounted to the base  12 . The socket  13  forms therein a fitting chamber  131  and a receiving chamber  132  for receiving the base  12  therein. The receiving chamber  132  has opposite left and right side walls that define left and right positioning slots  133 ,  134  respectively. The power cord  20  is formed by first clamping left and right conductive plates  15 ,  16  to conductive cores  211 ,  221  of two electrical wires  21 ,  22  and then positioned into the socket  13  through an open bottom thereof to allow the left and right conductive plates  15 ,  16  to be fit into the left and right positioning slots  133 ,  134  of the socket  13  by pulling the wires  21 ,  22  downward thereby securing the left and right conductive plates  15 ,  16  in the left and right positioning slots  133 ,  134 . After completion of the assembling of the power cord  20 , the base  12  to which the illuminator  11  is mounted is fit into the fitting slot  131  of the socket  13  to have the terminal pins  111  of the illuminator  11  engaging the left and right conductive plates  15 ,  16  whereby the assembling of the lamp  10  and the power cord  20  is completed. 
     To couple the conventional lamp  10  to the power cord  20 , the left and right conductive plates  15 ,  16  that are clamped to the electrical wires  21 ,  22  must be pulled downward to forcibly fit the left and right conductive plates  15 ,  16  into the left and right positioning slots  133 ,  134  respectively. This operation can only be done manually. Thus, the assembling operation of the lamp  10  to the power cord  20  cannot be automatized, and this makes the manufacturing costs high. 
       FIG. 2  shows the arrangement of a lamp and a power cord of a conventional juxtaposing-wire lighting string. The lamp, which is also designated at  10 , comprises an illuminator  11 , a base  12 , a socket  13 , and a bottom member  14 . The illuminator  11  comprises an LED having two terminal pins  111  and is mounted to the base  12 . The socket  13  forms therein a fitting chamber  131  and a receiving chamber  132  for receiving the base  12  therein. The receiving chamber  132  has opposite left and right side walls that define left and right positioning slots  133 ,  134  respectively. A left conductive plate  15  that has two opposite edges forming barbs  151  and a bottom edge forming piercing tips  152  and a right conductive plate  16  that has two opposite edges forming barbs  161  and a bottom edge forming piercing tips  162  are provided and respectively fit into the left and right positioning slots  133 ,  134 . The power cord  20  is a juxtaposing-wire cable composed of at least three electrical wires that are arranged to juxtapose each other and are directly positioned on the bottom of the socket  13 . The bottom member  14  is forcibly pushed upward to drive the juxtaposing wires into the socket  13  to allow the piercing tips  152 ,  162  of the left and right conductive plates  15 ,  16  to pierce into the power cord  20  to complete the assembling and electrical engagement therebetween. After completion of the assembling of the power cord  20 , the base  12  to which the illuminator  11  is mounted is fit into the fitting slot  131  of the socket  13  to have the terminal pins  111  of the illuminator  11  engaging the left and right conductive plates  15 ,  16  whereby the assembling of the lamp  10  and the power cord  20  is completed. 
     The coupling between the lamp and the power cord of the above discussed juxtaposing-wire lighting string requires no clamping of the conductive plates to the wires of the power cord, so that machine based automatization of the assembling operation can be realized. However, such a lamp is of a single-loop arrangement, and a configuration of juxtaposing arrangement of three wires is shown. The more the variation of the loop of the lighting string is, the more the number of the wires will be. Consequently, the manufacturing cost of the lighting string is increased. This again makes the overall cost of production high. 
     SUMMARY OF THE INVENTION 
     The primary purpose of the present invention is to provide a lamp structure of a dual-wire lighting string, which includes piercing conductive plates respectively fit into left and right positioning slots defined in a socket and a bottom member, which forcibly drives a power cord, in a deformed manner, into the bottom of the socket to allow the two conductive plates to respectively pierce into two electrical wires of the cord to electrically connect conductive cores of the wires. With such an arrangement, no clamping of the conductive plates to the electrical wires before assembling of the lamp to the electrical cord and thus machine based automatization of the assembling operation can be realized to reduce the cost of production and improve efficiency of production. 
     The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
     Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view showing the arrangement of a conventional lamp of a dual-wire lighting string. 
         FIG. 2  is an exploded view showing the arrangement of a conventional lamp of a juxtaposing-wire lighting string. 
         FIG. 3  is an exploded view showing a lamp of the present invention for a decorative lighting string. 
         FIGS. 4 and 5  are respectively an exploded view in broken form and schematic plan view showing the spatial relationship between the lamp of the present invention and a power cord. 
         FIG. 6  is a perspective view showing the lamp of the present invention mounted to the power cord. 
         FIGS. 7 and 8  are cross-sectional views illustrating the connection between the lamp of the present invention and the power cord. 
         FIGS. 9A-9C  are schematic views showing various arrangements of lighting strings in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
     As shown in  FIGS. 3-6 , the present invention provides a lamp structure of a dual-wire lighting string. The lamp of the present invention, which is generally designated at  10 , comprises a bulb or illuminator  11 , a base  12 , a socket  13 , and a bottom member  14 . A power cord  20  that supplies power to the lamp  10  is composed of a dual-wire configuration. The illuminator  10  is for example a light-emitting diode (LED) having two conductive terminal pins  111 . The base  12  has opposite left and right sides each forming a central projection in which a groove  121  is defined. The grooves  121  function to receive and retain the two terminal pins  111  of the LED therein, thereby coupling the illuminator  11  to the base  12 . The socket  13  forms, in a first end portion thereof, a fitting chamber  131  and a receiving chamber  132  communicating each other, for receiving the base  12  to fit therein. A support plate  135  is formed inside the socket  13  to define a bottom of the receiving chamber  132 . The receiving chamber  132  has opposite left and right side walls in which left and right positioning slots  133 ,  134  are respectively defined. The socket  13  has an open second end portion forming an open cavity in which two retention blocks  136  are formed on opposite side walls of the socket  13  below the support plate  135 . The open second end of the socket  13  forms, in the side walls thereof, wire slots  137  that are opposite to each other in a direction that is set at an angle less than 90 degrees with respect to the positioning slots  133 ,  134 . A left conductive copper plate  15  that has two opposite edges forming barbs  151  and a bottom edge forming two piercing tips  152  that define therebetween a wire fitting notch  153  at a central portion of the bottom edge and a right conductive copper plate  16  that has two opposite edges forming barbs  161  and a bottom edge forming two piercing tips  162  that define therebetween a wire fitting notch  163  at a central portion of the bottom edge are provided and respectively fit into the left and right positioning slots  133 ,  134  and are securely retained in the positioning slots  133 ,  134  by the barbs  151 ,  161  thereof. The bottom member  14  forms in a central portion thereof a stand  141 . The stand  141  has a top forming a receiving channel  142  for receiving and supporting the power cord  20 . The stand  141  forms pawls  143  on sides thereof that are opposite left and right sides of the receiving channel  142  and the stand  141  also forms retention ribs  144  on opposite front and rear sides thereof. The power cord  20  is positioned in the wire slots  137  defined in opposite side walls of the second, bottom end of the socket  13 . The bottom member  14  receives and supports two wires  21 ,  22  that constitute the power cord  20  with two recesses defined in the receiving channel  142  and is forced upward to fit into the open bottom end of the socket  13  to position the power cord  20  against the support plate  135 . Since the wire slots  137  are formed in opposite side walls of the socket  13  to oppose each other in a direction that is set at a predetermined angle less than 90 degrees with respect to the positioning slots  133 ,  134 , the length of the two wires  21 ,  22  is set inclined with respect to the left and right conductive copper plates  15 ,  16  by an angle less than 90 degrees, as best seen in  FIG. 5 . Under this situation, the two piercing tips  152  of the left conductive copper plate  15  may pierce through an insulation outer cover layer of the wire  21  to have the wire fitting notch  153  fit over and clamping a conductor core  211  of the wire  21  so as to form electrical connection therebetween, and the two piercing tips  162  of the right conductive copper plate  16  may pierce through an insulation outer cover layer of the wire  22  to have the wire fitting notch  163  fit over and clamping a conductor core  221  of the wire  22  so as to form electrical connection therebetween. At the same time, the pawls  143  of the bottom member  14  are forced into engagement with retention blocks  136  of the socket  13  to securely couple the bottom member  14  and the power cord  20  to the socket  13 . Since the power cord  20  is pierced through and clamped by the left and right conductive copper plates  15 ,  16  and is also tightly held by be pressed by the retention ribs  144 , as shown in  FIGS. 7 and 8 , the power cord  20  can maintain secured coupling with the socket  13  even through it is subjected to powerful stretching or pulling. The base  12  to which the LED illuminator  11  is coupled is then fit into the receiving chamber  132  of the socket  13  from the upper side to have the two terminal pins  111  of the LED illuminator  11  respectively engaging the left and right conductive copper plates  15 ,  16 , whereby the assembling of the lamp  10  and the power cord  20  to each other is completed. With the above discussed arrangement, the assembling of the lamp and the power cord can be done without first clamping conductive copper plates around electrical wires, so that the assembling operation can be carried out in an automatized manner with machines and the manufacturing costs can be reduced. 
     Referring to  FIGS. 9A ,  9 B, and  9 C, arrangements of lighting string in accordance with the present invention are schematically illustrated. The lighting string shown in  FIG. 9A  demonstrates a serial arrangement of the power cords  20  and lamps  10 . The lighting string shown in  FIG. 9B  demonstrates a parallel arrangement of the power cords  20  and lamps  10 . The lighting string shown in  FIG. 9C  demonstrates combined serial and parallel arrangement of the power cords  20  and lamps  10 . 
     While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.