Patent ID: 6580182
Filing Date: 2003-06-17
Classification: H01K,H05B

Abstract:
A filament shunted light string comprising the combination of:at least 35 electrical bulb supporting sockets connected in an electrical series circuit arrangement with each other and adapted to be energized by a power source of 120 volt A.C. electrical potential connectable to input terminals thereof, and with each of said sockets being adapted to have an electrically operable miniature incandescent lamp for Christmas tree lighting and decoration inserted therein and are illuminated whenever said A.C. electrical potential is applied to said input terminals, wherein said miniature incandescent bulbs draw a current up to approximately 200 milliamperes each, resulting in a power dissipation per bulb equal to or less than approximately one-half watt; voltage responsive switching means formed of at least one Zener diode connected in parallel across each of said sockets, said Zener diode having a Zener breakdown voltage approximately equal to or greater than the rated peak voltage of said bulbs, wherein half of said Zener diodes in said light string conduct in one direction during a first half of the A.C. cycle, and half of said Zener diodes in said light string conduct in a direction opposite to said first direction during a second half of the A.C. cycle; and means connecting said input terminals to a source of A.C. voltage whereby all illuminated bulbs in said string continue to receive substantially rated current therethrough and continue to be illuminated and the voltage drop across each bulb and the brightness of each bulb remains substantially unchanged even though multiple bulbs in the string are not illuminated for whatever reason, or are actually missing from their respective sockets.