Method and apparatus for igniting a gas discharge lamp

• US 6,172,468 B1
• Filed: 01/04/1999
• Issued: 01/09/2001
• Est. Priority Date: 01/14/1997
• Status: Expired due to Term

• Current Assignee: Metrolight Ltd.
• Original Assignee: Metrolight Ltd.
• Inventors: Holländer, Jonathan
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): TRAN, CHUC
• Application Number:
  US09/225,044
• Time in Patent Office: 736 Days
• Field of Search: 315/209.R, 315/119, 315/308, 315/175, 315/291, 315/307, 315/224, 315/225, 315/278, 315/DIG.7
• US Class Current: 315/291
• CPC Class Codes: H05B 41/2883 the controlled element being a DC/AC converter in the final stage, e.g. by harmonic mode starting
• CPC Class Codes: H05B 41/2888 the bridge being commutated at low frequency, e.g. 1kHz
• CPC Class Codes: H05B 41/388 for a transition from glow to arc

Abstract

A gas discharge lamp and a method of operating the lamp is provided. The gas discharge lamp includes a lamp, a ballast for providing an AC voltage to the lamp and a frequency changer which selects an initial AC frequency at which the ballast provides the AC voltage and which changes the AC frequency to a second AC frequency, wherein the second frequency is higher than the initial frequency.

Claims

1. A method of operating a high intensity discharge lamp, the method comprising the steps of:

during ignition operating said high intensity discharge lamp at an initial alternating current frequency which is lower than an operating alternating current frequency; and

later operating said high intensity discharge lamp at said operating alternating current frequency.

2. A method according to claim 1 and wherein said step of later operating occurs once said high intensity discharge lamp has substantially achieved a standard operating voltage.

3. A method according to claim 1 and wherein said initial alternating current frequency has a period which is long enough to maintain gas ionization during an alternating current voltage direction change.

4. A method according to claim 1 and wherein the change from the initial alternating current frequency to the second alternating current frequency is a step function.

5. A method according to claim 1 and wherein the change from the initial alternating current frequency to the second alternating current frequency is a ramp function.

6. A method according to claim 1 and wherein the change from the initial alternating current frequency to the second alternating current frequency is an increasing function.

7. A high intensity discharge lamp system comprising:

a high intensity discharge lamp;

a ballast for providing an alternating current voltage to said high intensity discharge lamp; and

a frequency changer which selects an initial alternating current frequency at which said ballast provides said alternating current voltage and which changes said alternating current frequency to a second alternating current frequency,

wherein said second frequency is an operating frequency and said initial frequency is lower than said operating frequency.

8. A lamp system according to claim 7 and wherein said frequency changer selects said second alternating current frequency once said high intensity discharge lamp has substantially achieved a standard operating voltage.

9. A lamp system according to claim 7 and wherein said initial alternating current frequency has a period which is long enough to maintain gas ionization during an alternating current voltage direction change.

10. A lamp system according to claim 7 and wherein the change from the initial alternating current frequency to the second alternating current frequency is a step function.

11. A lamp system according to claim 7 and wherein the change from the initial alternating current frequency to the second alternating current frequency is a ramp function.

12. A lamp system according to claim 7 and wherein the change from the initial alternating current frequency to the second alternating current frequency is an increasing function.