Dimming electronic ballast with preheat current control
First Claim
1. An electronic ballast for high frequency lighting of a discharge lamp having lamp filaments and operating in a preheating mode, a starting mode, a first lighting mode, and a second lighting mode, the electronic ballast comprising:
- an inverter;
a main resonant circuit coupled to the inverter; and
a preheating circuit having a winding component connected in parallel with the main resonant circuit, the winding component comprising a primary winding and a secondary winding, and a switch connected in series with the primary winding;
wherein a path of a current flowing in the primary winding of the winding component is switched ON by the switch in the first lighting mode and OFF in the second lighting mode, wherein the first lighting mode has a rated lamp output and the second lighting mode has a dimmed lamp output,wherein a constant preheating current for filaments in the lamp is supplied from the secondary winding of the winding component during the preheating mode, the starting mode, and the second lighting mode of the discharge lamp.
2 Assignments
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Accused Products
Abstract
An electronic ballast is capable of realizing high frequency lighting of a discharge lamp and switching between at least two lighting modes with different light outputs. The ballast includes a preheating circuit having a winding component connected in parallel with a main resonant circuit with a lamp current flowing therein for the discharge lamp. A constant preheating current for the lamp filaments is supplied from a secondary winding of the winding component during lighting of the discharge lamp and a path of a current flowing on a primary winding side of the winding component is switched by a switch according to the lighting mode.
19 Citations
20 Claims
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1. An electronic ballast for high frequency lighting of a discharge lamp having lamp filaments and operating in a preheating mode, a starting mode, a first lighting mode, and a second lighting mode, the electronic ballast comprising:
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an inverter; a main resonant circuit coupled to the inverter; and a preheating circuit having a winding component connected in parallel with the main resonant circuit, the winding component comprising a primary winding and a secondary winding, and a switch connected in series with the primary winding; wherein a path of a current flowing in the primary winding of the winding component is switched ON by the switch in the first lighting mode and OFF in the second lighting mode, wherein the first lighting mode has a rated lamp output and the second lighting mode has a dimmed lamp output, wherein a constant preheating current for filaments in the lamp is supplied from the secondary winding of the winding component during the preheating mode, the starting mode, and the second lighting mode of the discharge lamp. - View Dependent Claims (2, 3, 4, 5)
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6. An electronic ballast for powering a discharge lamp in a preheating mode, a starting mode, and a plurality of lighting modes, the ballast comprising:
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an inverter; a main resonant circuit coupled to a positive output terminal of the inverter and further coupled across the discharge lamp; a preheating circuit coupled in parallel with the main resonant circuit and comprising a primary winding of a transformer and a switching element coupled in series across the positive output terminal and a negative output terminal of the inverter, and further comprising a secondary winding of the transformer coupled across one or more filaments in the discharge lamp; and a dimming control circuit coupled to the switching element and configured to provide a pulse width modulated signal to turn on and off the switching element with an ON time which increases and decreases in accordance with an output power from the inverter to the lamp during the plurality of lighting modes of the ballast. - View Dependent Claims (7, 8, 9, 10)
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11. A lighting assembly for powering a fluorescent lamp, the lighting assembly comprising:
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a lighting fixture comprising an electronic ballast and a lamp socket configured to receive the lamp, the electronic ballast further comprising; an inverter comprising a plurality of inverter switches, a first resonant circuit coupled to a positive output terminal of the inverter, the first resonant circuit having an output power provided across the lamp, a second resonant circuit coupled to the positive output terminal of the inverter in parallel with the first resonant circuit and comprising a switch, the second resonant circuit having an output power provided across one or more filaments at either end of the lamp, and a switch control circuit configured to turn on and off the inverter switches in the inverter and the switch in the second resonant circuit, wherein the switch is turned on to enable a constant preheating current across one or more lamp filaments during a preheating mode and a starting mode; a receiving device effective to receive remote control signals and transmit said control signals to the switch control circuit; and a remote control signal transmitter configured to provide the remote control signals to the receiving device in association with; a first lighting mode having a first light output of the lamp, wherein the switch in the second resonant circuit is turned off to disable a constant preheating current across one or more lamp filaments, and a second lighting mode having a second light output less than the first light output, wherein the switch in the second resonant circuit is turned on to enable a constant preheating current across one or more lamp filaments. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification