Ignitor for high pressure arc discharge lamps

• US 5,013,977 A
• Filed: 03/09/1990
• Issued: 05/07/1991
• Est. Priority Date: 03/09/1990
• Status: Expired due to Term

• Current Assignee: North American Philips Corp. (Koninklijke Philips N.V.), Arctco Incorporated (Textron Inc)
• Original Assignee: North American Philips Corp. (Koninklijke Philips N.V.)
• Inventors: Droho, Joseph S.
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): Dinh, Son
• Application Number:
  US07/491,363
• Time in Patent Office: 424 Days
• Field of Search: 315/289, 315/290, 315/205, 315/239, 315/244, 315/DIG. 5, 315/240
• US Class Current: 315/289
• CPC Class Codes: H05B 41/042 using semiconductor devices

Abstract

An ignitor or starting circuit for a high pressure arc discharge lamp including a voltage sensitive bidirectional switch and an impedance with a resistor and inductor in series circuit. An additional capacitor is connected in parallel across the voltage sensitive switch and the resistor.

Claims

1. Apparatus for igniting and operating a high pressure discharge lamp comprising:

a pair of input terminals for connection to a source of low frequency AC supply voltage,

a pair of output terminals for connection to the electrodes of the high pressure discharge lamp,

inductance means having a winding coupled to at least one of said output terminals,

a first capacitor,

an impedance means including a resistor and an inductor in a first series circuit,

means connecting said first capacitor and said impedance means in a second series circuit,

additional means coupling said second series circuit to said input terminals by way of a part of said inductance means,

a voltage sensitive switching element coupled to said first capacitor and to said inductance means and operable to at least partly discharge said first capacitor when the voltage across said first capacitor equals a predetermined breakdown voltage of the switching element,

a second capacitor, and

further means coupling said second capacitor to said inductance means and to a junction point between said resistor and said inductor of said impedance means.

2. Apparatus as claimed in claim 1, wherein said first capacitor and said switching element are connected in series across said winding of said inductance means.

3. Apparatus as claimed in claim 2, wherein said second capacitor is connected in parallel across said voltage sensitive switching element and said resistor of said impedance means.

4. Apparatus as claimed in claim 3, wherein said inductance means comprises an autotransformer with a secondary having first and second legs.

5. Apparatus as claimed in claim 4, wherein said inductance winding connected in parallel with said first capacitor and said switching element is the first leg of the secondary of said autotransformer.

6. Apparatus as claimed in claim 5, wherein one end of said second capacitor and one end of said voltage sensitive switching means is connected to a junction point between the first leg and the second leg of the secondary of said autotransformer.

10. An ignitor as claimed in claim 4, wherein said transformer winding connected in parallel with said first capacitor and said switching element is the first leg of the secondary of said autotransformer.

11. An ignitor as claimed in claim 10, wherein one end of said second capacitor and one end of said voltage sensitive switching means is connected to a junction point between the first leg and the second leg of the secondary of said autotransformer.

12. Apparatus as claimed in claim 3, wherein said inductance means is a simple reactor.

13. Apparatus as claimed in claim 3, wherein a third capacitor is connected between said inductance means and said inductor.

14. Apparatus as claimed in claim 4, wherein said autotransformer has an isolated secondary.

7. An ignitor for a gas discharge lamp comprising first and second terminals for connection to a transformer winding and a third terminal for connection to a lamp electrode,

a first capacitor and an impedance means including a resistor with two end connections and an inductor in a first series circuit connected to one end of said resistor, said first capacitor and said impedance means connected in the series circuit between said first and third terminals,

a bidirectional voltage sensitive semiconductor switching element having a predetermined voltage threshold level connected between the second terminal and a terminal of the first capacitor remote from said first terminal, and

a second capacitor connected in parallel across said voltage sensitive switching element and said resistor and connected directly to said one end of said resistor.

8. An ignitor as claimed in claim 7, wherein said first capacitor and said switching element are connected in series across said transformer winding.

9. An ignitor as claimed in claim 8, wherein said transformer comprises an autotransformer with a secondary having first and second legs.