Abstract A conversion device is disclosed which adapts a three-way light fixture to the use of an ordinary electric bulb of the type having but a single filament. The device employs a pair of current controllers which can be activated separately or together by the three-way switch of the light fixture. Each controller governs the current flow to the filament during different half cycles of the full cycle of the impressed a.c. line voltage. One controller employs a trigger circuit to gate an SCR on at a predetermined phase of the a.c. wave whereby the SCR conducts current to the filament for a portion of a half wave to provide the lowest level of illumination. The other controller utilizes a diode to permit one half of the full wave alternating current to flow in the filament to provide an intermediate level of illumination. The highest level of illumination is obtained where the current controllers are activated together so that the diode conducts for one half of the a.c. cycle and the SCR conducts for a portion of the other half of the a.c. cycle.
A device for causing a lamp of the type having a filament heated to incandescence by alternating current electricity to provide three levels of illumination, the device comprising a housing forming a receptacle for receiving the base of the lamp, the housing having a hollow base adapted to be screwed into a three-way socket, first and second electrodes in the housing for making electrical connections to the filament of the lamp, a first unidirectionally conductive current controller connected to the first electrode, the first current controller being adapted to be conductive for substantially a half cycle in each cycle of the alternating current, a second unidirectionally conductive current controller connected to the first electrode, the second controller being arranged relative to the first electrode to conduct current in the direction opposite to the current conduction of the first controller, and the second current controller being adapted to be conductive for substantially less than a half cycle in each cycle of the alternating current, the first and second controllers being disposed within the hollow base of the housing, and the base having an insulative member carrying two external electrodes, each external electrode being connected to a different controller in the base whereby each controller can be separately electrically energized.
Claim 2
Independent Claim
208 words
A device for causing a lamp of the type having a filament heated to incandescence by alternating current electricity to provide three levels of illumination, the device comprising a housing forming a receptacle for receiving the base of the lamp, the housing having a hollow base adapted to be screwed into a three-way socket, first and second electrodes in the housing for making electrical connections to the filament of the lamp, a first unidirectionally conductive current controller connected to the first electrode, the first current controller being adapted to be conductive for substantially a half cycle in each cycle of the alternating current, a second unidirectionally conductive current controller connected to the first electrode, the second controller being arranged relative to the first electrode to conduct current in the direction opposite to the current conduction of the first controller, and the second current controller being adapted to be conductive for substantially less than a half cycle in each cycle of the alternating current, the first and second controllers being disposed within the hollow base of the housing, and the base having an insulative member carrying two external electrodes, each external electrode being connected to a different controller in the base whereby each controller can be separately electrically energized.
Claim 3
Dependent Claim
35 words
A device according to claim 1, wherein the second current controller includes an SCR and means for causing the SCR to be triggered into conduction at a predetermined phase angle of the alternating current electricity.