Lighting device with elliptical fresnel mirror

• US 20050270781A1
• Filed: 06/04/2004
• Published: 12/08/2005
• Est. Priority Date: 06/04/2004
• Status: Active Grant

• Current Assignee: Dale Marks
• Original Assignee: Dale Marks
• Inventors: Marks, Dale
• Granted Patent: US 7,178,947 B2
• Time in Patent Office: Days
• US Class Current: 362/298
• CPC Class Codes: F21V 14/02 by movement of light sources in vehicle head lamps F21S41/657
• CPC Class Codes: F21V 21/22 telescopic
• CPC Class Codes: F21V 7/0008 providing for indirect lighting
• CPC Class Codes: F21V 7/04 Optical design
• CPC Class Codes: F21V 7/09 with a combination of different curvatures
• CPC Class Codes: F21V 7/18 with provision for folding or collapsing
• CPC Class Codes: F21W 2131/107 of the exterior of buildings
• CPC Class Codes: F21W 2131/109 of gardens
• CPC Class Codes: F21W 2131/304 for pictures
• CPC Class Codes: F21W 2131/406 for theatres, stages or film studios
• CPC Class Codes: G03B 15/06 Special arrangements of screening, diffusing, or reflecting devices, e.g. in studio

Abstract

A lighting device has a Fresnel mirror with a reflective surface for reflecting light emitted by a light source onto a target. The reflective surface is defined by an elliptical curve. The light source is disposed at approximately the first focal point of an ellipse formed by the elliptical curve. A mechanism adjusts the functional relationship between the Fresnel mirror and the light source so that the light source can be positioned approximately at the first focal point of the ellipse.

Claims

1. A lighting device for lighting a target, the lighting device comprising:

a light source;

a Fresnel mirror having a reflective surface defined by a plurality of elliptical curves having a common first focal point and a common second focal point, the light source being substantially at the first focal point so that light from the light source is reflected from the Fresnel mirror toward the second focal point; and

means for setting a spacial relationship between the light source and the Fresnel mirror to adjust for elliptical Fresnel reflectors of different focal lengths, and to vary the pattern at the second focal point so that light reflected by the mirror is concentrated at the second focal point.

2. The lighting device of claim 1, including a secondary reflector between the light source and the second focal point for reflecting light from the light source toward the Fresnel mirror.

3. The lighting device of claim 2, wherein the Fresnel mirror has at least two sections which are pivotally connected to each other and means for folding the at least two sections of the Fresnel mirror against each other.

4. The lighting device of claim 3, wherein the means for folding comprises a hinge.

5. The lighting device of claim 2, wherein the at least two sections of the Fresnel mirror have the approximate same shape and size.

6. The lighting device of claim 1, wherein the Fresnel mirror is polygonal.

7. The lighting device of claim 1, further comprising a panel and a means for removably mounting the Fresnel mirror onto the panel.

8. The lighting device of claim 7, wherein the means for removably mounting the Fresnel mirror onto the panel is Velcro®

.

9. The lighting device of claim 1, wherein the means for setting the functional spacial relationship comprises a center strut which can be extended or reduced in length, the center strut is connected to the center of the Fresnel mirror at one end and to the light source at its other end.

10. The lighting device of claim 9, wherein the center strut has a telescopic frame.

11. The lighting device of claim 9, further comprising at least one side strut which extends from a side edge of the Fresnel mirror to the center strut.

12. The lighting device of claim 2, wherein the secondary reflector has a hemispherical shape.

13. The lighting device of claim 2, wherein the secondary reflector is connected to the center strut.

14. The lighting device of claim 13, wherein the secondary reflector further comprising a circumferential flange which is biased from the hemispherical shaped portion.

15. The lighting device of claim 2, further comprising a diffuser disposed between the Fresnel mirror and the light source and connected to the secondary reflector.

16. A lighting device for lighting a target, the lighting device comprising:

a light source;

a Fresnel mirror having a reflective surface which is defined at least in part by an elliptical curve having a first focal point and a second focal point, the Fresnel mirror is disposed in a functional spacial relationship relative to the light source, so that the light source is disposed approximately at the first focal point of an ellipse formed by the elliptical curve;

a center strut being connected to the center of the Fresnel mirror at one end and to the light source at its other end, the center strut being extendable or reducible in length so that the light source can be positioned approximately at the first focal point of the ellipse; and

a secondary reflector partially surrounding the light source and connected to the center strut with the light source, the reflector reflects light emitted from the light source toward the Fresnel mirror.

17. A lighting device of claim 16, wherein the Fresnel mirror has at least two sections which are pivotally connected to each other.

18. A lighting device for lighting a target, the lighting device comprising:

a light source;

a Fresnel mirror having a reflective surface which is defined at least in part by an elliptical curve having a first focal point and a second focal point, the Fresnel mirror having at least two sections which are pivotally connected, the Fresnel mirror being disposed in a functional spacial relationship relative to the light source, whereby the light source is disposed approximately at the first focal point of the ellipse;

a secondary reflector partially surrounding the light source, the reflector reflects light emitted from the light source toward the Fresnel mirror; and

a means for adjusting the functional spacial relationship between the light source and the Fresnel mirror so that the light source can be positioned approximately at the first focal point of the ellipse.

19. The lighting device of claim 18, wherein the means for adjusting comprises a center strut being connected to the center of the Fresnel mirror at one end and to the light source at its other end, the center strut being extendable or reducible in length so that the light source can be positioned approximately at the first focal point of the ellipse.

20. The lighting device of claim 18, further comprising a panel and a means for removably mounting the Fresnel mirror onto the panel.

21. The lighting device of claim 18, wherein the Fresnel mirror comprises a plurality of Fresnel sections and means for holding the sections to form the Fresnel mirror.

22. The lighting device of claim 18, wherein the Fresnel mirror comprises a 180-degree Fresnel mirror.

23. The lighting device of claim 22, wherein the light source is a linear light source.

24. The lighting device of claim 18, wherein the Fresnel mirror comprises a plurality of Fresnel sections and secondary struts for keeping the Fresnel sections in co-planar alignment with each other.