DIMMING ELECTRONIC BALLAST WITH PREHEAT CURRENT CONTROL
First Claim
1. A electronic ballast for high frequency lighting of a discharge lamp having lamp filaments and operating in at least two different lighting modes comprising:
- an inverter;
a main resonant circuit coupled to the inverter;
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;
a path of a current flowing in the primary winding of the winding component is switched by the switch in accordance with the different lighting modes; and
wherein a constant preheating current for filaments in the lamp is supplied from the secondary winding of the winding component during lighting of the discharge lamp.
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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.
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Citations
4 Claims
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1. A electronic ballast for high frequency lighting of a discharge lamp having lamp filaments and operating in at least two different lighting modes comprising:
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an inverter; a main resonant circuit coupled to the inverter; 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; a path of a current flowing in the primary winding of the winding component is switched by the switch in accordance with the different lighting modes; and wherein a constant preheating current for filaments in the lamp is supplied from the secondary winding of the winding component during lighting of the discharge lamp. - View Dependent Claims (2, 3, 4)
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Specification