Two-wire electronic dimming ballast for gaseous discharge lamps
AssigneeHoneywell Inc.
InventorZoltan Zansky
Life of this patent
Estimating the term…
Abstract
A low cost high frequency electronic dimming ballast for gas discharge lamps is disclosed which eliminates the need for external primary inductance or choke coils by employing leakage inductance of the transformer. The system is usable with either fluorescent or high intensity discharge lamps and alternate embodiments employ the push-pull or half-bridge inverters. Necessary leakage inductance and tuning capacitance are both located on the secondary of the transformer. Special auxiliary windings or capacitors are used to maintain necessary filament heating voltage during dimming of fluorescent lamps. A clamping circuit or auxiliary tuned circuit may be provided to prevent component damage due to over-voltage and over-current if a lamp is removed during operation of the system.
Claims29
A two-wire electronic ballast arrangement for one or more gas discharge lamps dimming comprising:
- a source of direct current;
- a source of variable square wave electric power;
- transistor inverter means adapted to be fed by said source of variable square wave electric power;
- transformer means comprising
- at least a first primary winding connected to said inverter and said source of direct current,
- a first secondary winding for supplying power to one or more gas discharge lamps,
- auxiliary secondary windings connected across the heating filaments of each gas discharge lamp,
- said first and said auxiliary secondary windings being disposed in predetermined spaced relation to said primary winding and said auxiliary secondary windings being disposed in predetermined spaced relation to said first secondary winding such that the voltage supplied to the heating filaments of said one or more gas discharge lamps remain substantially constant during variation of the voltage to said primary;
- tuning capacitor means connected across said first secondary winding selected to be in resonance with the leakage inductance of said first secondary winding to produce tuned sinusoidal input to said one or more lamps.
A two-wire electronic ballast arrangement for fluorescent dimming comprising:
- a source of variable direct current;
- self-oscillating series-transistor half-bridge inverter means connected across said source of direct current;
- transformer means having a primary winding connected from a point between the series transistors of said inverter and said direct current,
- first secondary winding having terminals connected to the heating filaments of a fluorescent lamp,
- second secondary winding having terminals connected across one of said fluorescent heating filaments;
- third secondary winding having terminals connected across the other of said fluorescent heating filaments;
- wherein said second and third secondary windings are disposed in predetermined spaced relation to said primary winding and said first secondary winding and said first secondary winding is disposed in predetermined spaced relation to said primary winding such that the voltage supplied to the heating filaments of said fluorescent lamp during variation of the source power remains substantially constant;
- and
- tuning capacitor means connected across said first secondary winding to produce sinusoidal input to said fluorescent lamp.
A two-wire electronic ballast arrangement for fluorescent dimming comprising:
- a source of variable direct current;
- self-oscillating, series-transistor, half-bridge inverter means connected across said source of DC current;
- transformer means having a primary winding connected from a point between the series transistors of said inverter and said source of DC current and secondary winding having terminals connects to one terminal of each of the filaments of a fluorescent lamp;
- first turning capacitor means connected across said secondary winding;
- second tuning capacitor means connected across the remaining terminals of each of the filaments of the fluorescent lamp to produce with said first tuning capacitor and said secondary winding tuned sinusoidal input to said lamp and to control variation in the voltage across the heating cathodes upon dimming of the lamp;
- and
- auxiliary tuned circuit means having an inductor and capacitor connected in parallel in series with said secondary winding wherein said auxiliary tuned circuit means is tuned to the same frequency as input to said lamp and adapted to prevent oscillation of said inverter upon removal of said lamp during operation of the ballast.
A two-wire electronic ballast arrangement for fluorescent dimming comprising:
- a source of variable direct current;
- self-oscillating series-transistor half-bridge inverter means connected across said source of direct current;
- transformer means having a primary winding connected from a point between the series transistors of said inverter and said source of direct current and secondary winding having terminals connected to one terminal of each of the filaments of a fluorescent lamp, and
- tuning capacitor means connected across the remaining terminals of each of the filaments of the fluorescent lamp to produce sinusoidal input to said lamp and to control with said secondary winding variation in the voltage across the heating cathodes upon dimming of the lamp or in the circuit upon removal of said lamp.
A two-wire electronic ballast arrangement for high intensity discharge lamp dimming wherein said lamps have a single terminal per cathode comprising:
- a source of direct current;
- a source of variable square wave electric power;
- transistor inverter means adapted to be fed by said square wave electric power;
- transformer means including a primary winding connected to said inverter and a secondary winding connected across one or more high intensity discharge lamps said transformer being constructed in a manner such that its natural leakage inductance appears in the secondary;
- and
- tuning capacitor means connected across said secondary winding to provide with said leakage inductance of said transformer a tuned circuit which provides tuned sinusoidal input to said one or more lamps.
Dependencies are inferred from the claim text.