Patent Publication Number: US-7905652-B2

Title: LED string light

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a light-emitting diode (LED) string light and, more particularly, to an LED string light that can be manufactured easily and efficiently with low labor cost. 
     2. Description of Related Art 
     Nowadays, commercially available LED string lights are manufactured typically by inserting leads of LED units directly into ends of conductive wires or by using a coupling mechanism to couple the leads of the LED units with the ends of the conductive wires. Therefore, not only are a considerable amount of time and labor required for assembling the LED units and the conductive wires, but also the LED string lights thus produced may have unstable quality due to the complicated manufacturing process. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of the above-cited drawbacks of the existing LED string lights, the inventor of the present invention conducted extensive study on the structure of LED string lights and explored ways to simplify the manufacturing process, and increase the production, of LED string lights so as to make quality, high-precision LED string lights. Finally, an LED string light was successfully developed and disclosed herein. 
     The present invention provides an LED string light that can be manufactured easily and efficiently with low labor cost. 
     The disclosed LED string light includes at least two conductive wires, a plurality of LED units, and a plurality of enclosures. The LED string light is characterized in that each of the LED units has leads inserted perpendicularly into the conductive wires to establish electrical connection therebetween and allow the bottom of the LED unit to abut against ends of the conductive wires. In addition, each of the enclosures has two through holes formed therein for the conductive wires to pass through, respectively, and an upper end provided with an accommodating space for receiving and enclosing a lower portion of the LED unit and part of the conductive wires. 
     In the disclosed LED string light, the leads of the LED unit are partially bent at a distance from the bottom of the LED unit, and the distance is equal to a distance from the ends of the conductive wires to holes formed in the conductive wires for the leads to pass through, thereby allowing the bottom of the LED unit to abut against the ends of the conductive wires. 
     In the disclosed LED string light, given that the distance from the bottom of the LED unit to where the leads of the LED unit are partially bent is equal to the distance from the ends of the conductive wires to the holes in the conductive wires for the leads to pass through, the LED string light is manufactured by first mechanically bending the leads of the LED unit at right angle at a position with a fixed distance from the bottom of the LED unit. Then, the conductive wires, which have been inserted respectively into the two through holes in the enclosure in advance, are attached with a boring jig, leaving a portion of the conductive wires above the enclosure with a length equal to the fixed distance, and the conductive wires are drilled at a distance from the ends of the conductive wires that is equal to the fixed distance. After that, the bent portions of the leads of the LED unit are directly inserted into the holes of the conductive wires while being perpendicular to the conductive wires, so that the bottom of the LED unit abuts against the ends of the conductive wires. Finally, the enclosure is moved upward to a connecting portion between the conductive wires and the LED unit to enclose the lower portion of the LED unit and part of the conductive wires. The foregoing process is performed for all the LED units, conductive wires, and enclosures until the LED string light according to the present invention is completed. 
     With the aforesaid simple configuration and easy production process, the LED string light according to the present invention is mass-produced in a concise manner with reduced labor requirement and low production cost, thus increasing economic advantage of the LED string light. 
     In addition, owing to its linear structure, the LED string light according to the present invention is set up, windingly if necessary, wherever a lighting or decorative effect is desired. For example, the LED string light is wound around Christmas trees and street trees as a decorative light. 
     The LED units in the LED string light according to the present invention can be light-emitting units that emit light of various colors. Hence, proper selection and combination of the colors of light emitted by the LED units of the LED string light according to the present invention brings a desired colorful lighting effect. 
     During manufacture, the conductive wires of the LED string light according to the present invention are inserted into the through holes of the enclosure in advance and then drilled with a boring jig at a predetermined location on the conductive wires. On the other hand, the LED unit is put in a positioning jig so that the leads of the LED unit are bent at right angle at a position with a predetermined distance from the bottom of the LED unit. Afterward, the bent portions of the leads are inserted into the holes pre-formed in the conductive wires to fix the LED unit in position to the conductive wires. Then, the enclosure is moved to the connecting portion between the LED unit and the conductive wires so that the lower portion of the LED unit and part of the conductive wires are received in the accommodating space of the enclosure. The foregoing steps are performed for all the LED units, conductive wires, and enclosures to complete the LED string light according to the present invention. 
     The LED units in the LED string light of the present invention can be connected in series or in parallel. For series connection, the anode and the cathode of one LED unit are connected to the cathode and the anode of an adjacent LED unit, respectively. For parallel connection, the anode and the cathode of one LED unit are connected to the anode and the cathode of an adjacent LED unit, respectively. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by referring to the following detailed description of illustrative embodiments in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an LED unit according to the present invention; 
         FIG. 2  is a partially sectional view showing conductive wires inserted into an enclosure according to a first embodiment of the present invention; 
         FIG. 3  is a partially sectional view showing alignment between the LED unit and the conductive wires according to the first embodiment of the present invention; 
         FIG. 4  and  FIG. 5  are partially sectional views showing different stages of a process for assembling the LED unit, the conductive wires, and the enclosure according to the first embodiment of the present invention; 
         FIG. 6  is a partially sectional view showing conductive wires inserted into an enclosure according to a second embodiment of the present invention; and 
         FIG. 7  is a partially sectional view showing alignment between the LED unit and the conductive wires according to the second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides an LED string light including at least two conductive wires, a plurality of LED units, and a plurality of enclosures. The LED string light is technically characterized in that each of the LED units has leads inserted perpendicularly into the conductive wires to establish electrical connection therebetween and allow the bottom of the LED unit to abut against ends of the conductive wires.  FIGS. 1 and 2  show the LED unit and the conductive wires according to the present invention, respectively, while  FIG. 3  shows alignment therebetween.  FIGS. 4 and 5  further show different stages of a process for assembling the LED unit, the conductive wires, and the enclosure according to the present invention. Referring to  FIG. 1  for a perspective view of the LED unit according to the present invention, an LED unit  1  includes a main body  11  having the bottom thereof provided with two leads. The leads are bent at 90° at a position with a fixed distance L from the bottom of the LED unit  1  to form leads  21 ,  21  and leads  22 ,  22 . Referring to  FIG. 2  for a partially sectional view showing the conductive wires inserted into the enclosure according to a first embodiment of the present invention, an enclosure  33  is formed therein with two through holes  331  for two conductive wires  31 ,  31  to pass through, respectively. The enclosure  33  has an upper end provided with an accommodating space  332  (shown in  FIGS. 3 ,  4 , and  5 ) for receiving and enclosing a lower portion of the LED unit  1  and part of the conductive wires  31 ,  31 . The two conductive wires  31 ,  31  are inserted into the through holes  331  of the enclosure  33  in advance. The conductive wires  31 ,  31  are formed with holes  32 ,  32  in advance, respectively. The holes  32 ,  32  are spaced from corresponding ends  311 ,  311  of the conductive wires  31 ,  31  by a distance L′, wherein the distance L′ is equal to the distance L of the leads  21 ,  21  of the LED unit  1  in  FIG. 1 . 
     Please refer to  FIGS. 3 to 5 , wherein  FIG. 3  shows alignment between the LED unit  1  and the conductive wires  31 , and  FIGS. 4 and 5  show different stages of a process for assembling the LED unit  1 , the conductive wires  31 , and the enclosure  33 . The leads  22  of the LED unit  1  are first aligned with the holes  32  of the conductive wires  31  and then inserted into the holes  32  perpendicularly to the conductive wires  31 . Thus, the bottom of the LED unit  1  abuts against the ends  311  of the conductive wires  31 , as shown in  FIG. 4 . Next, the enclosure  33  is moved toward the ends  311  of the conductive wires  31  so that under the action of the enclosure  33 , a portion of the leads  22  that protrude from the conductive wires  31  is bent toward the ends  311  of the conductive wires  31  and then received in the through holes  331  of the enclosure  33 . Meanwhile, the lower portion of the LED unit  1  and the ends  311  of the conductive wires  31  are both received in the accommodating space  332 , as shown in  FIG. 5 . The foregoing steps for assembling the LED unit  1 , the conductive wires  31 , and the enclosure  33  are performed for all the LED units, conductive wires, and enclosures to complete the LED string light according to the present invention. 
     According to the LED string light disclosed above, the pre-formed holes  32  of the conductive wires  31  also serve as positioning mark to facilitate assembly, and the leads of the LED unit  1  are bent corresponding in position to the holes  32 . Therefore, during assembly, the LED unit  1  is directly aligned with and precisely inserted into the holes  32 , thereby not only saving the time and labor otherwise required for assembly, but also preventing errors in the position of the leads relative to the conductive wires  31  which might otherwise occur due to misjudgment by assembly workers. In consequence, the throughput and efficiency of production are both increased while production time is significantly reduced. 
     In  FIGS. 1 through 5 , the LED units of the LED string light according to the present invention are connected in series. However, the LED units can also be connected in parallel in the LED string light according to the present invention, as explained below. 
     Parallel connection between the LED units of the LED string light according to the present invention is now demonstrated by reference to  FIGS. 1 ,  6 , and  7 . Referring to  FIG. 6  for a partially sectional view showing conductive wires inserted into an enclosure according to a second embodiment of the present invention, an enclosure  33  is formed therein with two through holes  331 , one larger than the other, for two conductive wires  31  to pass through, respectively. The enclosure  33  has an upper end provided with an accommodating space  332  for receiving and enclosing a lower portion of an LED unit  1  and part of the conductive wires  31 . One of the conductive wires  31  is folded back and inserted into the larger one of the through holes  331 , with both ends of the folded-back conductive wire  31  being connected to adjacent LED units  1 , respectively. As shown in  FIG. 6 , the conductive wire  31  on the left is folded 180° onto itself to form a folded-back end  312 . The folded-back end  312  is level with an end  311  of the other conductive wire  31 . The conductive wires  31  are formed with holes  32 ,  32 , respectively. The holes  32 ,  32  are spaced from the corresponding end  311  or end  312  by a distance L′, which is equal to the distance L of the leads  21  of the LED unit  1  in  FIG. 1 . Refer now to  FIG. 7  for a partially sectional view showing alignment between the LED unit  1  and the conductive wires  31  according to the second embodiment of the present invention. The LED unit  1  has leads  22  aligned with the holes  32  of the conductive wires  31  and then inserted into the holes  32  perpendicularly to the conductive wires  31 , so that the bottom of the LED unit  1  abuts against the ends  311  and  312  of the conductive wires  31 . Afterward, the enclosure  33  is pushed toward the ends  311  and  312  of the conductive wires  31  or, alternatively, the conductive wires  31  are pulled downward with respective to the enclosure  33 . Thus, under the action of the enclosure  33 , a portion of the leads  22  that protrudes from the conductive wires  31  is bent toward the ends  311  and  312  of the conductive wires  31  and received in the through holes  331  of the enclosure  33 . Meanwhile, the lower portion of the LED unit  1  and the ends  311  and  312  of the conductive wires  31  are received in the accommodating space  332 , thereby concluding a process for assembling the LED unit  1 , the conductive wires  31 , and the enclosure  33 , wherein the folded-back conductive wire  31  is further connected to the next LED unit. The LED string light according to the present invention is completed by performing the steps described above on all the LED units, conductive wires, and enclosures. 
     In the first embodiment of the present invention as illustrated in  FIGS. 1 through 5 , each of the conductive wires  31  is connected between the anode of one LED unit to the cathode of an adjacent LED unit, wherein the anode of the first LED unit is connected to the anode of a rectifier (not shown), and the cathode of the last LED unit is connected to the ground end of the rectifier. In this embodiment, a series connection structure is provided that is ideal for home decoration, such as being wound around Christmas trees, as well as party decoration, so as to produce a beautifying and decorative effect. 
     In the second embodiment of the present invention as depicted in  FIGS. 1 ,  6 , and  7 , the LED string light makes a parallel-connected circuit. A parallel-connected circuit differs from a series-connected circuit in the following way. A series-connected circuit consists of a single loop. If any element in the loop is damaged, the entire circuit is broken, and all the other elements will not work. On the contrary, a parallel-connected circuit consists of a plurality of loops. Taking for example the LED string light according to the second embodiment of the present invention, should one of the parallel-connected LED units be damaged, a user can easily locate the damaged LED unit while all the other LED units are in normal operation. Therefore, a parallel-connected LED string light is suitable for decorating street trees and may produce a colorful, sparkling effect when used with an oscillator and LED units capable of emitting light of different colors.