Single ballast for powering plural high intensity discharge lamps

• US 5,986,412 A
• Filed: 05/22/1997
• Issued: 11/16/1999
• Est. Priority Date: 11/13/1996
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Collins, Byron R.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Lee, Wilson
• Application Number:
  US08/861,923
• Time in Patent Office: 908 Days
• Field of Search: 315/209 CD, 315/290, 315/289, 315/307, 315/323, 315/291, 315/208, 315/297, 315/DIG. 5, 315/308, 315/247, 315/151
• US Class Current: 315/291
• CPC Class Codes: H05B 41/042 using semiconductor devices
• CPC Class Codes: H05B 41/18 having a starting switch

Abstract

A ballast circuit for a plurality of serially connected, high pressure gas discharge lamps comprises an electromagnetic ballast arrangement receptive of an input power signal, providing an output ballast voltage for driving the plurality of lamps, and providing an open circuit ballast voltage when the lamps are disconnected from the arrangement. A first ignitor circuit is connected between the ballast arrangement and the first lamp, and produces at least one ignitor pulse of high voltage and high frequency compared to the open circuit ballast voltage, to initiate starting of the first lamp. A second ignitor circuit is connected between the first lamp and a second lamp so as to be supplied with current through the first lamp. The second circuit produces at least one ignitor pulse of high voltage and high frequency compared to the open circuit ballast voltage after the first lamp begins to start and drops substantially in impedance, to initiate starting of the second lamp.

Claims

1. A ballast circuit for a plurality of serially connected, high pressure gas discharge lamps without heated filaments, comprising:

(a) an electromagnetic ballast arrangement receptive of an input power signal, providing an output ballast voltage for driving said plurality of lamps which are without heated filaments, and providing an open circuit ballast voltage when said lamps are disconnected from said arrangement;

(b) a first ignitor circuit connected between said ballast arrangement and a first lamp, and producing at least one ignitor pulse of high voltage and high frequency compared to said open circuit ballast voltage, to initiate starting of said first lamp; and

(c) a second ignitor circuit connected between said first lamp and a second lamp so as to be supplied with current through said first lamp;

said circuit producing at least one ignitor pulse of high voltage and high frequency compared to said open circuit ballast voltage after said first lamp begins to start and drops substantially in impedance, to initiate starting of said second lamp.

2. The ballast circuit of claim 1, wherein said second ignitor circuit comprises:

(a) a voltage-breakover device;

(b) a capacitor coupled to said device in such manner that the voltage of said capacitor increases with current supplied through said first lamp to a point at which said device fires; and

(c) a pulse transformer having an input winding coupled across said device and an output winding coupled across said second lamp for applying an ignitor pulse thereto.

4. The ballast circuit of claim 1, wherein each of said high pressure gas discharge lamps comprises one of a metal halide lamp, a mercury lamp, and a limited dose sodium lamp.

9. The ballast circuit of claim 1, wherein said ballast circuit lacks a capacitor shunting said first lamp.

3. A ballast circuit for a plurality of serially connected, high pressure gas discharge lamps, comprising:

(a) an electromagnetic ballast arrangement receptive of an input power signal, providing an output ballast voltage for driving said plurality of lamps, and providing an open circuit ballast voltage when said lamps are disconnected from said arrangement;

(b) a first ignitor circuit connected between said ballast arrangement and a first lamp, and producing at least one ignitor pulse of high voltage and high frequency compared to said open circuit ballast voltage, to initiate starting of said first lamp; and

(c) a second ignitor circuit connected between said first lamp and a second lamp so as to be supplied with current through said first lamp;

said circuit producing at least one ignitor pulse of high voltage and high frequency compared to said open circuit ballast voltage after said first lamp begins to start and drops substantially in impedance, to initiate starting of said second lamp;

said second ignitor circuit comprising;

(i) a voltage-breakover device;

(ii) a capacitor coupled to said device in such manner that the voltage of said capacitor increases with current supplied through said first lamp to a point at which said device fires; and

(iii) a pulse transformer having an input winding coupled across said device and an output winding coupled across said second lamp for applying an ignitor pulse thereto;

(d) said ballast arrangement supplying a ballast voltage having a fundamental component and a peak component substantially higher in voltage than said fundamental component; and

(e) said second ignitor circuit including a capacitive voltage-divider network receptive of said ballast voltage and arranged to impress part of said peak component across said device to cause it to fire while said peak component is present in said ballast voltage.

5. A ballast circuit for a plurality of serially connected, high pressure gas discharge lamps without heated filaments, comprising:

(a) an electromagnetic ballast arrangement receptive of an input power signal, providing an output ballast voltage for driving said plurality of lamps which are without heated filaments, and providing an open circuit ballast voltage when said lamps are disconnected from said arrangement;

(b) a first ignitor circuit connected between said ballast transformer arrangement and a first lamp, and producing at least one ignitor pulse of high voltage and high frequency compared to said open circuit ballast voltage, to initiate starting of said first lamp; and

(c) a second ignitor circuit connected between said first lamp and a second lamp so as to be supplied with current substantially entirely through said first lamp;

said circuit producing at least one ignitor pulse of high voltage and high frequency compared to said open circuit ballast voltage after said first lamp begins to start and drops substantially in impedance, to initiate starting of said second lamp.

6. The ballast circuit of claim 5, wherein said second ignitor circuit comprises:

(a) a voltage-breakover device;

(b) a capacitor coupled to said device in such manner that the voltage of said capacitor increases with current supplied through said first lamp to a point at which said device fires; and

(c) a pulse transformer having an input winding coupled across said device and an output winding coupled across said second lamp for applying an ignitor pulse thereto.

7. The ballast circuit of claim 6, wherein:

(a) said ballast transformer arrangement supplies a ballast voltage having a fundamental component and a peak component substantially higher voltage than said fundamental component; and

(b) said second ignitor circuit includes a capacitive voltage-divider network receptive of said ballast voltage and arranged to impress part of said peak component across said device to cause it to fire while said peak component is present in said ballast voltage.

8. The ballast circuit of claim 6, wherein each of said high pressure gas discharge lamps comprises one of a metal halide lamp, a mercury lamp, and a limited dose sodium lamp.

10. The ballast circuit of claim 5, wherein said ballast circuit lacks a capacitor shunting said first lamp.