Wedding ring shaped excitation coil

• US 6,326,739 B1
• Filed: 07/14/2000
• Issued: 12/04/2001
• Est. Priority Date: 01/13/1998
• Status: Expired due to Fees

• Current Assignee: Fusion Lighting, Inc.
• Original Assignee: Fusion Lighting, Inc.
• Inventors: Tsai, Peter, MacLennan, Donald A.
• Primary Examiner(s): Philogene, Haissa
• Application Number:
  US09/616,993
• Time in Patent Office: 508 Days
• Field of Search: 315/248, 315/39, 315/111.51, 315/344, 313/231.31, 313/231.41, 313/231.61, 313/231.71, 313/153, 313/154, 313/634
• US Class Current: 315/248
• CPC Class Codes: H01J 61/12 Selection of substances for gas fillings; Specified operating pressure or temperature
• CPC Class Codes: H01J 61/125 having an halogenide as principal component
• CPC Class Codes: H01J 61/523 Heating or cooling particular parts of the lamp
• CPC Class Codes: H01J 65/044 the field being produced by a separate microwave unit
• CPC Class Codes: H01J 65/048 the field being produced by using an excitation coil
• CPC Class Codes: H05B 41/24 in which the lamp is fed by high frequency ac, or with separate oscillator frequencyH05B41/26 takes precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency.

Claims

1. An excitation coil for an inductively coupled electrodeless lamp, the excitation coil comprising a substantially non-helical, semi-cylindrical conductive surface having less than one turn, the inductively coupled lamp further including an envelope enclosing a fill and a source of excitation energy connected to the coil.

2. The excitation coil as recited in claim 1, wherein the conductive surface comprises a wedding ring shape.

3. The excitation coil as recited in claim 1, wherein the conductive surface has a relatively thin radial thickness and an axial height at least greater than the radial thickness.

4. The excitation coil as recited in claim 3, wherein the axial height is between about one-third and about two-thirds of a diameter of the conductive surface.

5. An excitation coil for an inductively coupled electrodeless lamp, the excitation coil comprising a conductive surface having a wedding ring shaped excitation portion and first and second leads bent tangential to the excitation portion and parallel to each other, the conductive surface having a cross-sectional shape generally corresponding to the upper-case Greek letter omega, the inductively coupled lamp further including an envelope enclosing a fill and a source of excitation energy connected to the coil.

6. An excitation coil for an inductively coupled electrodeless lamp, the excitation coil comprising one or more conductive surfaces configured to provide at least two current loops, wherein the at least two current loops are spaced apart from and substantially parallel to and in phase with each other, the inductively coupled lamp further including an envelope enclosing a fill and a source of excitation energy connected to the coil.

7. The excitation coil as recited in claim 6, wherein the one or more conductive surfaces are configured to provide two semi-circular current loops, the two semi-circular current loops being substantially parallel to and in phase with each other and having a substantially same axis and diameter, wherein the two current loops are spaced apart by a height which is about 40 to 60 percent of the diameter of the two semi-circular current loops.

8. The excitation coil as recited in claim 6, wherein the one or more conductive surfaces comprise a single non-helical, semi-cylindrical surface having less than one turn.

9. The excitation coil as recited in claim 6, wherein the one or more conductive surfaces comprise two non-helical, semi-cylindrical surfaces, each having less than one turn.

10. The excitation coil as recited in claim 9, wherein the two non-helical, semi-cylindrical surfaces are connected in parallel.

11. An excitation structure for an inductively coupled electrodeless lamp, the excitation structure comprising two excitation coils connected in parallel, spaced apart from and substantially parallel to each other, the inductively coupled lamp further including an envelope enclosing a fill and a source of excitation energy connected to the coil.