Abstract:
A shunt device for a light socket includes a semiconductor chip which is operably interposed between a pair of electric terminals of the socket. The sockets are in series for a conventional set of display lights, such as holiday lights.

Description:
FIELD OF INVENTION 
   The present invention relates to a lamp socket for light strings having lights arranged in series. More particularly, the invention relates to a semiconductor chip and conductive member for use in a light socket forming a shunt to allow for electricity to continually conduct throughout the light string keeping the remainder of the lights lit when one or more lights on the string burn out, become dysfunctional or are removed from a socket. 
   BACKGROUND OF THE INVENTION 
   Decorative light strings which are connected in series are highly popular in the United States, especially during holidays in November and December. A drawback with such light strings is that they commonly include of a plurality of individual light units with bulbs which are electrically connected in series and not in parallel. The bulbs are typically incandescent bulbs having a filament formed between two leads of the bulb, the filament giving off light when a current is passed from one lead to the other, through the filament. As the bulb is used, over time, the filament will burn out, breaking the series circuit in which the bulb is arranged. This will cause the entire light string to go out unless a backup circuit path is available to bypass the failed filament. Presently, inside of the mini-light bulb, there is a backup circuit path having a shunt system arranged in parallel with the filament of each bulb. This shunt is comprised of three turns of aluminum wire with an insulating (oxide) coating. When the filament is intact, current passes through the filament because the resistance of the filament is low compared to that of the insulating material on the shunt. However, when the filament burns out, the voltage across the leads of the bulb increases to the full line potential of 120 volts AC. The actual peak voltage at 120 volts AC is approximately 170 volts. The insulating coating on the shunt wire is designed to break down at a minimum of 40 volts to provide a backup circuit path around the failed filament. However, this ‘shorting’ mechanism only works about 70% of the time. When it fails to operate, the entire series-wired light string goes out. 
   One solution that allows the circuit to continue to function when there is a failure as described above is taught in U.S. Pat. Nos. 6,084,357 and 6,580,182 which is issued to the same inventor herein. The solution is to provide a backup circuit path having a semiconductor shunt system arranged in parallel with the filament of each bulb. As described in the above mentioned issued patents, the semiconductor device might be a diode array or back-to-back Zener diodes. In this manner, even if a bulb burns out, breaks, or falls out of its socket, the rest of the light units in the light string remain on because the series circuit remains closed. 
   The system employed in the above issued patents is the shunting of each light bulb in the string with such a semiconductor shunt mounted in a package as the standard DO-41 package. The DO-41 package housing the semiconductor chip is placed inside of each socket and is electrically connected to the light bulb&#39;s conductive connection in the socket. 
   While the availability of decorative light strings using this type of shunt works well, there remains a need to improve shunts as set forth herein. Further, there is need to decrease the cost of producing the decorative light string. 
   BRIEF SUMMARY OF THE INVENTION 
   It is an object to improve decorative light strings. 
   It is another object to reduce the cost of decorative light strings. 
   It is a further object to provide a semiconductor chip inside of a light socket without the need for a separate housing such as the DO-41 package. 
   Accordingly, an embodiment of the present invention is directed to a shunt device for use in a light socket having a semiconductor chip held in place by a spring-like tension conductive member. Another embodiment provides for the chip to be held in place by conductive leads having terminal ends which plug into electric terminals of the sockets. Still another embodiment is directed to a bent conductive member having the chip sandwiched between a pair of conductive terminals with bias toward one another to retain the same by the conductive terminals. In yet another embodiment, the conductive terminals can be modified to include retention fingers which are opposing each other in a spaced relationship in a manner to form a retaining seat for the chip which can be preferably sandwiched in between. Still another embodiment provides for a chip to be directly connected to each conductive terminal and have a conductive wire interconnecting the two chips, wherein each chip is intended to dissipate half of the power keeping the socket from overheating in cases where too much current is drawn, such as when higher watt light bulbs are used. 
   The light socket of the instant invention is for use with a light string having at least two light sockets connected in series via wire segments having associated contact elements. A light bulb is receivable by each socket and can be removed and replaced when a filament of the bulb burns out. 
   Other objects will be revealed by the following description and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partial sectional view of one embodiment of the invention. 
       FIG. 2  is a partial sectional view of another embodiment. 
       FIG. 3  is a partial sectional view of an existing socket. 
       FIG. 4  is a partial sectional view of yet another embodiment of the invention. 
       FIG. 4   a  is a blow up of a part of  FIG. 4 . 
       FIG. 5  is a partial sectional view of still another embodiment of the invention. 
       FIG. 6  is a partial sectional view of another embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings, the semiconductor chip of the present invention is generally designated by the numeral  10 . The semiconductor chip  10  is a relatively flat and thin plate which is of the type described in U.S. Provisional Patent Application No. 60/471,094. The chip  10  is used in various embodiments described herein. 
     FIG. 1  shows a modified light socket  12  having conductive terminals  14  on each side with plug-in socket surfaces  16  formed therein in a portion of each terminal  14  where a light bulb  17  normally seats when operatively disposed within the socket  12 . The light bulb  17  has a pair of conductive leads which connect to a filament contained within a glass envelope. The chip  10  may include operatively connected conductive leads  18 , wherein one lead  18  extends from each side  20  and  22  of the chip  10  and can be bonded thereto by a conductive epoxy, for example. A terminal end  24  of each lead  18  is configured to be operatively received into the plug-in socket surfaces  16 . The leads  18  can be of a suitable conductive material such as copper. 
     FIG. 2  shows an alternative embodiment wherein the semiconductor chip  10  is bonded to bent conductive members  126  which each have an inwardly disposed flange  124 . The socket  120  has a housing  121  to receive the light bulb  17  and a pair of opposing conductive terminals  122 . The terminals  122  are connected to wires  125  which operatively extend outside the housing  120 . The chip  10  can be bonded, e.g., with an epoxy, to flange  124 . When operatively disposed, the chip  10  is disposed adjacent and between the flanges  124 . 
     FIG. 3  shows an existing socket  12 ′ and bulb  17 ′. The socket  12 ′ shorts when the bulb  17 ′ is removed. 
   In yet another embodiment,  FIG. 4  shows bent conductive terminals  50  and  52  having retention fingers  54  and  56 , respectively, which are opposing each other in a spaced relationship such that the fingers  54  and  56  do not touch. The terminals  50  and  52  contact conductive terminals  140 . The fingers  54  and  56  can be set at an angle to aid in this regard. When operatively disposed in socket  150 , the fingers  54  and  56  form part of a retaining seat for chip  10  along with lower portions  58  and  60  of the terminals  50  and  52 , respectively. The chip  10  can be inserted between terminals  50  and  52  so that the terminals  50  and  52  do not touch. 
   Still another embodiment shown in  FIG. 5  provides for chips  10  and  10 ′ to be conductively directly connected to conductive terminals  200  and  200 ′ within socket  202 . Again, the chips  10  and  10 ′ can be bonded directly to the terminals  200  and  200 ′ on one side. A conductive wire  250  interconnects the two chips  10  and  10 ′ and likewise the ends of the wire  250  can be press fit between (and optionally bonded) to the other side of each respective chip  10  and  10 ′. Each chip  10  and  10 ′ is intended to dissipate half of the power keeping the socket  202  from overheating in cases where too much current is drawn, such as when higher watt light bulbs are used. 
     FIG. 6  shows another embodiment. Here, the operation is similar to that of  FIG. 5 . However, a conductive compression spring  300  is used to connect chips  10  and  10 ′ with each end of the spring  300  conductively connected to one side of the respective chips  10  and  10 ′. The spring  302  is configured to bias the chips  10  and  10 ′ into retained conductive contact with terminals  302  and  302 ′ in socket  350  below where the light bulb  17  is operatively seated. Once operatively disposed in the socket  350 , the chips  10  and  10 ′ can be bonded to the terminals  302  and  302 ′, if desired, or contact allowed to be made by the compression spring  300 . 
   The above described embodiments are set forth by way of example and are not for the purpose of limiting the present invention. It will be readily apparent to those skilled in the art that obvious modifications, derivations and variations can be made to the embodiments without departing from the scope of the invention. Accordingly, the claims appended hereto should be read in their full scope including any such modifications, derivations and variations.