Inductively coupled incandescent light bulb

• US 5,905,343 A
• Filed: 10/10/1995
• Issued: 05/18/1999
• Est. Priority Date: 10/10/1995
• Status: Expired due to Fees

• Current Assignee: Angus J. Mccamant
• Original Assignee: Angus J. Mccamant
• Inventors: McCamant, Angus J.
• Primary Examiner(s): LEE, BENNY T
• Application Number:
  US08/541,501
• Time in Patent Office: 1,316 Days
• Field of Search: 315/57, 315/62, 315/248, 315/267, 315/344, 313/156-158, 313/160, 313/161, 313/113, 313/485
• US Class Current: 315/57
• CPC Class Codes: H01K 11/00 Lamps having an incandescent body which is not conductively heated, e.g. heated inductively, heated by electronic discharge H01K13/00 takes precedence

Abstract

An incandescent bulb having a looped filament within an evacuated bulb containing a gas mixture including a halogen employs magnetic means external to the bulb to provide inductive heating of the filament so that there are no connections passing through the bulb envelope. Alternative embodiments include a toroidal bulb wherein a second arm of a magnetic circuit passes normally through the center of the bulb toroid, alternating voltage excitation being supplied to a first arm of the magnetic circuit; and an elliptical bulb that is disposed between oppositely facing ends of a two-part second magnetic arm that is similarly excited. In a further embodiment, an additional arm of the magnetic circuit serves to form a non-uniform field in the vicinity of the filament, thereby to provide a lift force against the force of gravity so as to minimize filament sagging.

Claims

1. An incandescent bulb comprising:

an evacuated bulb;

a gas filling within said evacuated bulb;

a filament in the form of an ellipse lying in a filament plane;

holding means for holding said filament; and

magnetic means for inducing an electrical current within said filament and heating said filament to incandescence.

2. The bulb of claim 1 wherein said evacuated bulb is toroidal in shape;

and said filament is centrally disposed within a cross-section of said evacuated bulb throughout a circumference thereof.

3. The bulb of claim 2 wherein said magnetic means comprise:

first magnetic means comprising a high permeability magnetic circuit having first and second sides;

first excitation means for applying a varying magnetic field to said first side;

wherein said second side passes orthogonally through a plane defining the location of said evacuated bulb and through a center of said evacuated bulb toroid.

4. The bulb of claim 1 wherein said evacuated bulb is elliptical in shape;

and said filament comprises a closed loop disposed centrally within said evacuated bulb.

5. The bulb of claim wherein 1 said magnetic means comprise:

a high permeability magnetic circuit having first and second sides and excitation means for applying a varying magnetic field to said first side; and

said second side further includes a gap near a midpoint thereof; and

said evacuated bulb is located within said gap such that the filament plane lies normally to a longitudinal axis of said second side.

6. The bulb of claim 5 wherein said second side further comprises:

a pair of cusp-shaped faces disposed in a mutually facing relationship across said gap.

7. The bulb of claim 6 wherein said cusp-shaped faces have shapes so as to provide an intensified magnetic field above said filament.

8. The bulb of claim 6 further comprising:

a third magnetic side near to and essentially parallel to said second side;

second excitation means for providing a magnetic field within said third magnetic side; and

a terminal gap face that terminates said third magnetic side and is oriented in a direction facing towards one of said cusp-shaped faces.

9. The bulb of claim 8 wherein said terminal gap face has a size that is smaller than a respective size of said cusp-shaped gap faces, whereby a non-uniform magnetic field is provided about said filament.

10. The bulb of claim 9 wherein said terminal gap face has a shape such that said non-uniform magnetic field will have nearly the same field strength about a circumference of said filament.

11. A method for producing light from an evacuated bulb comprising:

providing a loop filament disposed within an evacuated bulb;

inducing an electrical current within said filament using a magnetic circuit responsive to a first magnetic field to excite a primary side of said magnetic circuit; and

heating said loop filament to incandescence with said electrical current.

12. The method of claim 11 further comprising:

providing said evacuated bulb that is toroidal in shape;

disposing said filament within a circumference of said evacuated bulb; and

providing a second magnetic field by passing a secondary side of said magnetic circuit orthogonally through a center of said evacuated bulb.

13. The method of claim 11 further comprising:

providing said evacuated bulb that is toroidal in shape;

disposing said filament centrally within said evacuated bulb; and

providing a second magnetic field by locating said evacuated bulb within a gap between oppositely facing faces of a secondary side of said magnetic circuit.

14. A method of providing lift to a filament disposed within an evacuated bulb comprising:

providing an upper magnetic face disposed above said evacuated bulb;

providing a lower magnetic face disposed below said evacuated bulb, said lower magnetic face having a larger cross-sectional area than a cross-sectional area of said upper magnetic face;

providing a magnetic field passing between said upper and lower magnetic faces, said magnetic field being more intense near to said upper magnetic face than near to said lower magnetic face; and

deriving from said magnetic field a net upward force acting on said filament thereby providing the lift to the filament.