Fluorescent lamp ballast with selectable power levels
First Claim
1. In combination with a lamp circuit including a fluorescent lamp having first and second cathodes with resistive-heating filaments each spaced at a respective end of a lamp tube;
- first and second power leads for respectively connecting said cathodes to an a.c. power source whose power can be selectively enabled and interrupted by a main power switch; and
a ballast inductor being in serial circuit with one of said power leads and including a plurality of filament-heating windings for supplying power to said cathodes;
a power-level selection circuit interposed between a first cathode and a filament-heating winding, comprising;
(a) a power-receiving circuit coupled to said filament-heating winding to receive power therefrom;
(b) a filament-supply circuit for continuously supplying available power to said first cathode; and
(c) a selectable-impedance circuit serially coupled between said first power lead and said first cathode and being responsive to a predetermined duration of interruption of power from said a.c. source to said power leads for selecting a different impedance of said selectable-impedance circuit, thereby selecting a different power level of said lamp.
1 Assignment
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Accused Products
Abstract
Disclosed is a power-level selection circuit in combination with a lamp circuit including a fluorescent lamp having first and second cathodes with resistive-heating filaments each spaced at a respective end of a lamp tube; first and second power leads for respectively connecting the cathodes to an a.c. power source whose power can be selectively enabled and interrupted by a main power switch; and a ballast inductor in serial circuit with one of the power leads and including a plurality of filament-heating windings for supplying power to the cathodes. The power-level selection circuit is interposed between a first cathode and a filament-heating winding, and includes a power-receiving circuit coupled to the filament-heating winding to receive power therefrom. Further included is a filament-supply circuit for continuously supplying available power to the first cathode. A selectable-impedance circuit is serially coupled between the first power lead and the first cathode and is responsive to a predetermined duration of interruption of power from the a.c. source to the power leads for selecting a different impedance of the selectable-impedance circuit, thereby selecting a different power level of the lamp.
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Citations
18 Claims
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1. In combination with a lamp circuit including a fluorescent lamp having first and second cathodes with resistive-heating filaments each spaced at a respective end of a lamp tube;
- first and second power leads for respectively connecting said cathodes to an a.c. power source whose power can be selectively enabled and interrupted by a main power switch; and
a ballast inductor being in serial circuit with one of said power leads and including a plurality of filament-heating windings for supplying power to said cathodes;
a power-level selection circuit interposed between a first cathode and a filament-heating winding, comprising;(a) a power-receiving circuit coupled to said filament-heating winding to receive power therefrom; (b) a filament-supply circuit for continuously supplying available power to said first cathode; and (c) a selectable-impedance circuit serially coupled between said first power lead and said first cathode and being responsive to a predetermined duration of interruption of power from said a.c. source to said power leads for selecting a different impedance of said selectable-impedance circuit, thereby selecting a different power level of said lamp. - View Dependent Claims (2, 3, 4, 5, 6)
- first and second power leads for respectively connecting said cathodes to an a.c. power source whose power can be selectively enabled and interrupted by a main power switch; and
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7. In combination with a lamp circuit including a fluorescent lamp having first and second cathodes with resistive-heating filaments each spaced at a respective end of a lamp tube;
- first and second power leads for respectively connecting said cathodes to an a.c. power source whose power can be selectively enabled and interrupted by a main power switch; and
a ballast inductor being in serial circuit with one of said power leads and including a plurality of filament-heating windings for supplying power to said cathodes;
a power-level selection circuit interposed between a first cathode and a filament-heating winding, comprising;(a) a power-receiving circuit coupled to said filament-heating winding to receive power therefrom; (b) a filament-supply circuit for continuously supplying available power to said first cathode; and (c) a selectable-impedance circuit serially being coupled between said first power lead and said first cathode and being responsive to repeated, predetermined durations of interruption of power from said a.c. source to said power leads for toggling between a first and a second impedance of said selectable-impedance circuit, thereby providing two different power levels of said lamp. - View Dependent Claims (8, 9, 10, 11, 12)
- first and second power leads for respectively connecting said cathodes to an a.c. power source whose power can be selectively enabled and interrupted by a main power switch; and
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13. For use in combination with a lamp circuit including a fluorescent lamp having first and second cathodes with resistive-heating filaments each spaced at a respective end of a lamp tube;
- first and second power leads for respectively connecting said cathodes to an a.c. power source whose power can be selectively enabled and interrupted by a main power switch; and
a ballast inductor being in serial circuit with one of said power leads and including a plurality of filament-heating windings for supplying power to said cathodes;
a power-level selection circuit interposed between a first cathode and a filament-heating winding, comprising;(a) a power-receiving circuit coupled to said filament-heating winding to receive power therefrom; (b) a filament-supply circuit for continuously supplying available power to said first cathode; and (c) a selectable-impedance circuit serially coupled between said first power lead and said first cathode and being responsive to a predetermined duration of interruption of power from said a.c. source to said power leads for selecting a different impedance of said selectable-impedance circuit, thereby selecting a different power level of said lamp. - View Dependent Claims (14, 15, 16, 17, 18)
- first and second power leads for respectively connecting said cathodes to an a.c. power source whose power can be selectively enabled and interrupted by a main power switch; and
Specification