Arc discharge ballast suitable for automotive applications
First Claim
1. A ballast for operating an arc discharge lamp in a dc mode, said ballast comprising:
- first and second direct current input terminals;
pulse width modulator means coupled to said first and second direct current input terminals and including high frequency generating means and semiconductor switch means, said high frequency generating means developing a signal means for driving said semiconductor switch means;
first transformer means having primary and secondary windings, said primary winding being coupled to said semiconductor switch means;
rectifier and voltage multiplier means coupled to said secondary winding of said first transformer means for conversion of the voltage across aid secondary winding of said first transformer means to a direct current output voltage having a predetermined value;
first energy storage means coupled to said rectifier and volage multiplier means for storing energy for generating a high voltage spike sufficient for initiating a glow condition in said lamp;
second transformer means coupled to said first energy storage means for applying said high voltage spike to said lamp;
second energy storage means coupled to said rectifier and voltage multiplier means for storing energy for application to said lamp, said second energy storage means being effective in causing a glow-to-arc transition in said lamp; and
voltage and current sensing means for developing a control signal and means for coupling said control signal to said high frequency generating means.
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Accused Products
Abstract
A circuit for starting and operating a high intensity discharge (HID)lamp in a dc mode includes a pulse width modulator (PWM) coupled to first and second direct current input terminals. The PWM includes a high frequency generator driving a pair of semiconductor switches. A first transformer having primary and secondary windings is coupled to the semiconductor switches. A rectifier and voltage multiplier circuit converts the voltage across the secondary winding of the first transformer to a direct current voltage. A first energy storage circuit coupled to the rectifier and voltage multiplier circuit stores energy for generating a high voltage spike which initiates a glow condition in the lamp. A secondary energy storage circuit, which stores energy for application to the HID lamp during starting, insures proper glow-to-arc transition. The starting and operating circuit further includes a second transformer having first and second secondary windings coupled to the HID lamp and a pulse winding coupled to the first energy storage circuit. Preferably, the windings of the second transformer are adapted to apply a negative-going pulse across the lamp. The application of a negative-going pulse prevents failure of the quartz region of the glass around the lamp cathode by insuring that electrons properly migrate from the cathode to the anode. Moreover, the use of the negative-going pulse improves hot restriking.
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Citations
13 Claims
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1. A ballast for operating an arc discharge lamp in a dc mode, said ballast comprising:
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first and second direct current input terminals; pulse width modulator means coupled to said first and second direct current input terminals and including high frequency generating means and semiconductor switch means, said high frequency generating means developing a signal means for driving said semiconductor switch means; first transformer means having primary and secondary windings, said primary winding being coupled to said semiconductor switch means; rectifier and voltage multiplier means coupled to said secondary winding of said first transformer means for conversion of the voltage across aid secondary winding of said first transformer means to a direct current output voltage having a predetermined value; first energy storage means coupled to said rectifier and volage multiplier means for storing energy for generating a high voltage spike sufficient for initiating a glow condition in said lamp; second transformer means coupled to said first energy storage means for applying said high voltage spike to said lamp; second energy storage means coupled to said rectifier and voltage multiplier means for storing energy for application to said lamp, said second energy storage means being effective in causing a glow-to-arc transition in said lamp; and voltage and current sensing means for developing a control signal and means for coupling said control signal to said high frequency generating means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A ballast for operating a high intensity discharge lamp in a dc mode, said ballast comprising:
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first and second direct current input terminals; pulse width modulator means coupled to said first and second direct current input terminals and including high frequency generating means and semiconductor switch means, said high frequency generating means developing a signal means for driving said semiconductor switch means; first transformer means having primary and secondary windings, said primary winding being coupled to said semiconductor switch means; rectifier and voltage multiplier means coupled to said secondary winding of said first transformer means for conversion of the secondary winding voltage to a direct current output voltage having a predetermined value; first energy storage means coupled to said rectifier and voltage multiplier means for storing energy for generating a high voltage spike sufficient for initiating a glow condition in said lamp; second transformer means coupled to said first energy storage means and adapted to apply across the lamp said high voltage spike in a negative-going direction with respect to said output voltage; second energy storage means coupled to said rectifier and voltage multiplier means for storing energy for application to said lamp, said second energy storage means being effective in causing a glow-to-arc transition in said lamp; and voltage and current sensing means for developing a control signal and means for coupling said control signal to said high frequency generating means.
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Specification