Patent Publication Number: US-7591658-B2

Title: Light string with improved shunt system

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application claims priority under 35 USC §119 from Chinese patent application Serial No. 200620015418.0, filed on Oct. 25, 2006, entitled DECORATIVE LIGHT, the disclosure and application of which is incorporated by reference herein in its entirety. 
   TECHNICAL FIELD 
   The present utility model relates to a decorative light, and more particularly to a decorative light which keeps the circuit connected when one or several light bulbs fall off from the series-connected light bulbs of a light string (customarily it is called as a holiday decorative light.). 
   TECHNICAL BACKGROUND 
   In the prior arts, small light bulbs connected in series with a low voltage are lightened synchronously. The entire circuit is disconnected when one or more tungsten filaments are burn out or when one or more light bulbs fall off. 
   In order to resolve this problem, the Chinese Patent #CN95226975.9 discloses a light bulb with resistance wire, a circuit is established by the resistance wire when one or several tungsten filaments are burn out, which does not affect the other light bulbs. However, the resistance wire or fuse as disclosed in the Chinese patent #CN95226975.9 is arranged inside of the light bulb, a decorative light with the light bulbs is turned off when one or several light bulbs fall off, which results in the decorative light not working. 
   SUMMARY OF THE INVENTION 
   It is an object of the present utility model to provide a decorative light which keeps working when one or several light bulbs fall off to overcome the disadvantages of the above described prior arts, 
   The object of the present utility model is achieved by the following means: 
   The decorative light of the present utility model comprises a pipe-shaped lamp holder, a light bulb preassembled with a lamp base, two terminals arranged at the end of two wires. The lamp base and the terminals are respectively inserted into the inside of the lamp holder from two different ends of the lamp holder. The two electrodes of the light bulb are respectively connected to the two terminals. The decorative light is characterized in that a bulge is arranged at the end of the lamp base facing to the terminals and the bulge is close to one of the two terminals; a torsion spring made with conductive material is arranged in the inside of the lamp holder; the torsion spring is provided with two feet corresponding to the positions of the terminals, one foot is contacted with one of the terminals, and the other foot has spacing with the other one of the terminals due to the pressure from the bulge on the lamp base; the two feet of the torsion spring are respectively contacted with their corresponding terminals by means of a torsion force from the torsion spring when the lamp base falls off from the lamp holder. 
   The torsion spring has a pipe shape with wound steel wire, and has a hollow passage. 
   An end plug is provided in the inside of the lamp holder and the end plug is arranged between the two terminals. A post is set at the end plug and the post is fitted into the hollow passage of the pipe-shaped torsion spring. 
   As compared with the prior arts, a light string formed with the decorative light of the present utility model keeps alit when one or several assembled bulbs and lamp bases fall off, which is because the torsion spring makes the circuit connected immediately by means of a torsion force. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an assembly diagram according to an embodiment of the present utility model. 
       FIG. 2  is a disassembly diagram according to an embodiment of the present utility model. 
       FIG. 3  is an assembly diagram according to another embodiment of the present utility model. 
       FIG. 4  is a disassembly diagram according to another embodiment of the present utility model. 
   

   DETAILED DESCRIPTION OF THE INVENTION  
   A detailed description of the present utility model will be shown below with reference to the figures. 
     FIG. 1  and  FIG. 2  show an embodiment of the present utility model. Bulb  101  and lamp base  102  are preassembled together, and then an assembled body of the bulb  101  and the lamp base  102  is inserted into one end of the lamp holder  103 . The copper terminals  105  are pressed into the ends of the wires  107 ; there are two wires  107  as well as two copper terminals  105  provided; the copper terminals  105  are inserted in the other end of the lamp holder  103 . As shown in  FIG. 1 , the two copper terminals  105  are respectively connected to the two electrodes  111  of bulb  101 . There is a bulge  108  at the end of the lamp base  102  facing to the copper terminals  105 . The bulge is close to one of the two terminals  105 . A torsion spring  104  made with steel wire is arranged in the lamp holder  103 . The torsion spring  104  is provided with two feet corresponding to the positions of the copper terminals  105 , one foot is in contact with one of the terminals  105 , and the other foot is spaced apart from the other of the terminals  105  due to the presence of the bulge  108  on the lamp base. The two feet of the torsion spring are respectively connected to their corresponding terminals to establish a circuit by means of the torsion force from the torsion spring when the assembled body of the lamp base  102  and the bulb  101  falls off from the lamp holder  103 . The torsion spring  104  of the present utility model has a pipe shape with wound steel wire, and has a hollow passage. An end plug  106  containing a recessed volume  109  is provided in the lamp holder  103  and the end plug is arranged between the two terminals  105 . A post  110  is set at the end plug  106  and the post is fitted into the hollow passage of the pipe-shaped torsion spring  104 . The torsion spring  104  makes the circuit connected by means of a torsion force when one or several assembled bulbs and the lamp bases fall off. 
     FIG. 3  and  FIG. 4  show an alternative embodiment of the present utility model. The features of these embodiments corresponds closely with those in  figure 1 and 2  and like designation numbers designate like features. Additional features in  figure 3 and 4  includes a second recessed volume  109  on the backside of end plug  106 , central disposition of torsion spring  104 , now with substantially equal length legs, on post  110  as affixed to end plug  106 , This arrangement provides for insertion of lamp base  102  into lamp holder  103  in one of two orientations, so that bulge  108  may disengage either of the two legs of torsion spring  104  to provide for electrical connection through the bulb  101 . 
   The decorative light of the present utility model is generally used with a plurality of decorative lights connected in series to form a string light. In order to avoid a power short circuit caused by the falling-off of all light bulbs from the string light, at least one light of the string light should not be the decorative light of the present embodiment. Alternatively, a decorative light with a fuse can be used or a decorative light of the present embodiment can be used in the string light after a torsion spring is removed. 
   The present utility model provides a decorative light which keeps working when one or several assembled light bulbs and lamp bases fall off.