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US 4,742,273 AGranted
Long life incandescent lamp
OwnerHerbert E. Goldberginventor
Life of this patent
Estimating the term…
Abstract
An extended life incandescent lamp which employs thermal, voltage, or radiation activated differential switching to substitute a series-connected reserve filament for an inoperative primary filament without increasing the normal in-rush current.
Claims5
A long life incandescent bulb switch comprising:
- terminals connectable to a source of power to supply power to a primary filament and a reserve filament when connected in series across said terminals,
- first sensing means operative to sense the presence or absence of voltage across said terminals,
- second sensing means operative to sense the presence or absence of current through said primary filament,
- switching means comprising a first, normally open shunt across said primary filament and a second, normally closed shunt across said reserve filament,
- said switching means responsive to said first and second sensing means and operative to close said first shunt and open said second shunt only when voltage is present at said terminals and current is absent through said primary filament;
- whereby the reserve filament is energized only upon failure of the primary filament.
3 more elements
A long life incandescent bulb switch comprising:
- terminals connectable to a source of power to supply power to a primary filament when connected across said terminals, and to a reserve filament and normally open switching means connected in series across said primary filament to form a normally open shunt across said primary filament,
- first sensing means operative to sense the presence or absence of voltage across said terminals,
- second sensing means operative to sense the presence or absence of current through said primary filament,
- said switching means responsive to said first and second sensing means and operative to close said shunt only when voltage is present at said terminals and current is absent through said primary filament;
- whereby said reserve filament is energized only upon failure of said primary filament.
2 more elements
A long life incandescent bulb switch comprising:
- terminals connectable to a source of power to supply power to a primary filament and current limiting means when connected in series across said terminals, and to a reserve filament when connected to first switching means,
- said first switching means comprising a normally closed switch connected in series with said reserve filament across said primary filament and a first, normally open shunt across said current limiting means,
- second switching means forming a second, normally open shunt across said current limiting means,
- first sensing means to sense the presence or absence of current through said primary filament,
- second sensing means to sense the presence or absence of current through said reserve filament,
- said first switching means being responsive to said first sensing means and operative to open said normally closed switch and to close said first shunt only when current is present through said primary filament,
- said second switching means being responsive to said second sensing means and operative to close said second shunt only when current is present through said reserve filament,
- said first sensing means operative to respond more rapidly than said second sensing means;
- whereby said reserve filament is fully energized only upon failure of said primary filament.
6 more elements
Dependencies are inferred from the claim text.