Method and apparatus for changing the emission characteristics of an electrodeless lamp

• US 4,954,756 A
• Filed: 10/11/1988
• Issued: 09/04/1990
• Est. Priority Date: 07/15/1987
• Status: Expired due to Term

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: Fusion Systems Corp (Eaton Corporation PLC.)
• Inventors: Mosher, David, Wood, Charles H.
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Razavi, Michael
• Application Number:
  US07/256,227
• Time in Patent Office: 693 Days
• Field of Search: 315/248, 315/112, 315/267, 315/447, 315/111.21, 315/39, 315/344, 315/117, 315/118, 313/35, 313/15, 313/44, 362/386, 362/373
• US Class Current: 315/39
• CPC Class Codes: H01J 65/04 Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels

Abstract

A method of modifying light and heat emission patterns from an electrodeless lamp which includes an envelope containing a plasma-forming medium and a source of electromagnetic energy coupled to the plasma-forming medium. The method consists of rotating the envelope at a rate fast enough to modify surface heating and the distribution of radiating plasma along lines of constant longitude on the envelope.

Claims

1. A method of changing the emission properties of an electrodeless lamp, said lamp comprising an envelope which contains a plasma-forming medium and means for coupling electromagnetic energy to the medium within said envelope to generate an electric field and form a light-emitting plasma, said method comprising establishing an axis of rotation which is at an angle of between about 30°

and 90°

with respect to the electric field, and rotating said envelope about said axis at a rate of at least about 1000 rpm, said rate being great enough for the centrifugal forces produced thereby to modify surface heating and the distribution of plasma-forming medium about the inner surface of said envelope and concomitantly change the emission properties of the electrodeless lamp, said rotation rate being significantly greater than that which is required to produce a substantially uniform temperature about lines of constant latitude of said envelope while leaving non-uniformities along lines of constant longitude.

2. The method according to claim 1 wherein the rotation is at a rate which is at least about 1500 RPM.

3. The method according to claim 1 wherein the envelope is a sphere having a diameter from about 0.75 to about 1.5 inches in diameter and the rotation rate is from about 1500 to about 2500 RPM.

7. The method of claims 1, 4, or 5 further comprising the step of directing at least one stream of cooling gas at the rotating envelope.

4. A method of changing the emission properties of an electrodeless lamp, wherein said lamp includes an envelope which contains a plasma-=forming medium and means for coupling electromagnetic energy to the medium within said envelope to generate an electric field and form a light-emitting plasma, said method comprising,

establishing an axis of rotation which is about perpendicular to the direction of the electric field, and

rotating said envelope about an axis at a rotation rate of at least about 1000 revolutions per minute, said rate being great enough for the centrifugal forces produced thereby to modify surface heating and the distribution of plasma-forming medium about the inner surface of said envelope and concomitantly change the emission properties of the electrodeless lamp, said rotation rate being significantly greater than that which is required to produce a substantially uniform temperature about lines of constant latitude of said envelope while leaving non-uniformities along lines of constant longitude.

6. The method of claim 4 wherein the rotation is at a rate which substantially equalizes the temperature distribution about the lamp envelope.

5. In an electrodeless lamp, a method of changing the temperature distribution around the surface of the lamp envelope, wherein said envelope contains a plasma forming medium and said lamp includes means for coupling microwave energy to said medium within said envelope to generate an electric field and form a light-emitting plasma, said method comprising,

establishing an axis of rotation which is at an angle of between about 30 degrees and 90 degrees to the direction of the electric field, and

rotating said envelope about said axis at a rotation rate of at least about 1000 revolutions per minute, wherein said rate is great enough for the centrifugal forces produced thereby to modify the surface heating of the envelope and the temperature distribution thereabout, said rotation rate being significantly greater than that which is required to produce a substantially uniform temperature about lines of constant latitude of said envelope while leaving non-uniformities along lines of constant longitude.