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US 4,580,079 AGranted
Multifilament bulb with filament switching device
OwnerRonald Kooinventor
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OwnerRonald Kooinventor
Estimating the term…
A filament switching device is arranged to be mounted within the screw base of a conventional, dual-filament, incandescent light bulb. The device has a frame which branches around the evacuation tube of the bulb thereby allowing sufficient room for switching components within the device and yet avoiding interference with the evacuation tube of the bulb. Mounted within the frame of the switching device is a fixed contact and a cantilevered contact. The cantilevered contact can swing in a direction transverse to the evacuation tube to make electrical contact with the fixed contact. The cantilevered contact is held separated from the fixed contact by a fusible conductor. Upon failure of one of the filaments in the bulb, a surge of current flows through the fusible conductor, parting it and allowing the cantilevered contact to swing into electrical contact with the fixed contact. This swing of the cantilevered contact substitutes the failed filament with the other filament.
In a multi-filament incandescent light bulb having a transparent or translucent evacuated bulb mounted in a screw type base and containing first and second filaments adapted to be electrically connected with electrical power supply contacts on said base, said bulb having an evacuation tube extending from said bulb into said base, a switching device in said base extending at least partially around said evacuation tube, and means in said switching device for automatically connecting said second filament to said power supply contacts upon failure of said first filament.
A switching device for a multifilament incandescent light bulb for automatically connecting a second filament to a power supply upon failure of a first filament comprising:
A method of assembling a switching device for automatically connecting a second filament of a multi filament bulb upon failure of the first filament in the bulb, comprising the steps of:
Dependencies are inferred from the claim text.