Tapered multilayer luminaire devices

• US 5,303,322 A
• Filed: 03/11/1993
• Issued: 04/12/1994
• Est. Priority Date: 03/23/1992
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: Nioptics Corporation
• Inventors: Gitkind, Neil A., Winston, Roland, Holman, Robert L., Jacobson, Benjamin A.
• Primary Examiner(s): Lee, John D.
• Assistant Examiner(s): PALMER, PHAN T H
• Application Number:
  US08/029,883
• Time in Patent Office: 397 Days
• Field of Search: 385/43, 385/129, 385/130, 385/131, 385/140, 385/146, 385/147, 385/901, 385/31, 359/599, 359/833, 359/834
• US Class Current: 385/146
• CPC Class Codes: F21V 5/02 of prismatic shape F21V5/04 takes precedence
• CPC Class Codes: G02B 6/0001 specially adapted for lighting devices or systems lighting or signalling on vehicles using light guides B60Q1/00; lighting devices for vehicle dashboards B60Q3/10; lighting devices for vehicle interior using light guides B60Q3/62; lighting devices mounted on the vehicle rear part using light guides F21S43/235; measuring arrangements having light conducting pointers G01D13/265; illumination of liquid crystal displays G02F1/1336; illuminated signs G09F13/00
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/4298 coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G09F 13/00 Illuminated signs; Luminous advertising G09F9/00, G09F11/00 take precedence; control of displays in general using static means to present variable information G09G
• CPC Class Codes: G09F 13/0409 Arrangements for homogeneous illumination of the display surface, e.g. using a layer having a non-uniform transparency arrangements of reflectors G09F13/14
• CPC Class Codes: G09F 2013/05 indicating exit way or orientation
• CPC Class Codes: G09F 2013/1827 Prismatic window
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

An optical device for collecting light and selectively outputting or concentrating the light. A wedge layer has an optical index of refraction n₁, and top, bottom and side surfaces intersecting to define an angle of inclination d. A back surface spans the top, bottom and side surface. A first layer is coupled to the bottom surface of the layer and has an index of refraction n₂. The first layer index n₂ causes light input through the back surface of the layer to be preferentially output into the first layer. A second layer is coupled to the bottom of the first layer and selectively causes output of light into ambient. Additional layers, such as an air gap, can be provided adjacent to the wedge shaped layer. The wedge shaped layer can also have a variable index of refraction n (x,y,z).

Claims

1. An optical device for collecting light from a source and for selectively outputting light, comprising:

a first layer capable of receiving light from said source and having an optical index of refraction n₁ and top and bottom layer surfaces converging to define at least one angle of inclination φ

, said first layer including a back surface spanning said top and bottom layer surfaces and the light exiting said first layer when the light being reflected therein decreases its angle of reflection relative to a normal to at least one of said top and bottom layer surfaces and achieves an angle of reflection less than the critical angle θ

_c relative to the normal;

layer means including an air gap underlying said bottom layer surface of said first layer and having an effective optical index of refraction n₂ for allowing transmission of light received form said first layer; and

light redirecting means at least one of overlying and underlying said layer means, said redirecting means allowing transmission of light across the thickness of said redirecting means for selectively redirecting light output from said layer means.

2. The optical device as defined in claim 1 wherein said light redirecting means underlying said layer means and said bottom layer surface reflects the light transmitted thereacross, the light being reflected back through said light redirecting means, through said layer means and through said first layer and output through said top layer surface overlying said light redirecting means.

3. The optical device as defined in claim 1 wherein said optical device provides a collimated light output having a cone of angular width Δ

Θ

approximately equal to [2φ

^1/2 (n² -1)⁴ ]2φ

^1/2 (n₁² -1)^1/4.

4. The optical device as defined in claim 1 further including a layer having a faceted portion for optically redirecting light, said faceted portion positioned at lease one of (a) between said source of light and said first layer, (b) overlying said first layer and (c) underlying said light redirecting means.

5. The optical device as defined in claim 1 further including at least one of (a) a diffuser layer disposed between said source of light and said first layer, (b) a diffuser layer overlying said first layer, (c) a diffuser layer underlying said light redirecting means, and (d) means for at least filling the numerical aperture of said first layer.

6. The optical device as defined in claim 1 wherein said light redirecting means has an index of refraction n₃ and the indices of refraction have one of the following combinations:

n₃ >

n₂ ;

n₂ >

n₁ ≦

₃ ;

n₁ ˜

1.5, n₂ <

1.5, n₃ ≧

n₁ ;

n₁ is about 1.4-1.7, n₂ <

1.4 and n₃ >

1.45;

₂ is about 1.

7. The optical device as defined in claim 1 wherein said light redirecting means causes light input to said first layer to preferentially be output from said bottom layer surface and through said light redirecting means into ambient.

8. The optical device as defined in claim 1 wherein said light redirecting means is disposed about said layer means forming an overlying and underlying layer symmetrically positioned about a line through said first layer and dividing the first layer into two portions of φ

/2.

9. The optical device as defined in claim 1 wherein said top and bottom surfaces converge at said angle of inclination Φ

and the light being output from said top and bottom surfaces is substantially symmetrically angularly distributed from said optical device.

10. The optical device as defined in claim 9 wherein said top and bottom surface converge at said at least one angle of inclination Φ

/2 and further including a reflecting layer disposed adjacent the air gap thereby causing light to be output through only one of said top and bottom surfaces.

11. The optical device as defined in claim 10 further including a coupled second one of said first layer, said air gap, said light redirecting means and said reflecting layer.

12. An optical device for collecting light from a source and for selectively outputting light to a viewer, comprising:

a first layer having a wedge shaped cross sectional area and having an optical index of refraction n₁, and a top and bottom surface converging to define at least one angle of inclination φ

, said first layer further including a back surface spanning said top and bottom surfaces, and the light exiting said first layer when the light being reflected therein decreases its angle of reflection relative to the normal to at least one of said top and bottom layer surfaces and achieves an angle of reflection less than the critical angle θ

_c relative to the normal;

an air gap layer underlying said bottom surface of said first layer and light thereby entering said air gap layer from said bottom wedge surface when the light in said first layer achieves the angle of reflection less than the critical angle of incidence characteristic of the interface between said first layer and said air gap; and

light redirecting means underlying said air gap, said light redirecting means for transmitting light traversing said air gap over a controlled angular output distribution for viewing by the user over a range of angles of substantially spatially uniform intensity.

13. The optical device as defined in claim 12 wherein said light redirecting means includes a layer overlying said air gap and also includes a reflection layer for reflecting the light through said first layer and said air gap for output.

14. The optical device as defined in claim 12 further including a light diffuser element at least one of (a) overlying said top layer surface (b) between said source of light and said first layer, and (c) underlying said light redirecting means.

15. The optical device as defined in claim 12 wherein said light redirecting means includes a faceted layer portion for optically redirecting light over a controlled angular distribution.

16. The optical device as defined in claim 15 wherein at least one of said first layer includes an associated faceted layer separated by said air gap and said layer having a faceted portion including an intervening air gap overlying said top layer surface.

17. The optical device as defined in claim 12 wherein said air gap layer is supported by at least one of an external support and an intra layer support between said first layer and said light redirecting means.

18. The optical device as defined in claim 12 wherein said light redirecting means comprises a specular reflector layer.

19. The optical device as defined in claim 12 further including an additional light redirecting means disposed above the top surface of said first layer.

20. The optical device as defined in claim 19 wherein said light redirecting means comprises an additional supported air gap disposed overlying said top surface of said first layer and a faceted layer underlying said air gap.

21. The optical device as defined in claim 19 wherein at least one of said light redirecting means and said additional light redirecting means comprises a plurality of facets wherein said facets have at least one of (a) different facet curvature and (b) substantially the same facet curvature.

22. The optical device as defined in claim 21 wherein said additional light redirecting means comprises a layer having a faceted surface for optically focusing the light for controlled angular distribution of light output into ambient.

23. The optical device as defined in claim 22 wherein n₁ is about 1.5, said additional air gap and said air gap have an optical index of refraction of unity and said layer having a faceted surface has an n₃ value of about 1.48-1.60.

24. The optical device as defined in claim 12 wherein said light redirecting means comprises a faceted portion for efficiently redirecting light within said angular width of 4φ

^1/2 (n₁² -1)^1/4.

25. An optical device able to collect light, including light from a substantially incoherent, uncollimated light source and for selectively outputting the light, comprising:

a first layer having an input surface capable of receiving light from said light source and an optical index of refraction n₁ and including converging top and bottom layer surfaces with said input surface forming the larger thickness end of said first layer and said first layer including a varying slope for at least one of said top and bottom layer surfaces, said varying slope able to include a converging and/or diverging portion of said first layer, and the light exiting said first layer when the light being reflected therein decreasing its angle of reflection relative to a normal to at least one of said top and bottom layer surfaces and achieves an angle of reflection less than the critical angle θ

_c relative to the normal,

layer means underlying said bottom layer surface of said first layer and having an optical index of refraction n₂ ; and

light redirecting means underlying said layer means for selectively reflecting and transmitting light received from said layer means, at least one of said varying slope first layer and said light redirecting means providing a controlled angular, substantially spatially uniform output of the light into ambient.

26. The optical device as defined in claim 25 wherein said light source provides light having an angular width greater than or equal to arcsin (1-(n₂ /n₁)²)^1/2.

27. The optical device as defined in claim 25 further including a light coupler comprised of at least one of a compound parabolic concentrator portion around said light source, a reflector around said light source having an involute light source portion, a linear prism, a light diffuser, means for at least filling the numerical aperature of said first layer, a light source reflector element including one or more nearly semicircular arcs and a nonimaging reflector.

28. The optical device as defined in claim 25 wherein the controlled angular output of the light has angular width of less than 4φ

^1/2 (n₁² -1)^1/4 wherein φ

is the angle of convergence of said top and bottom surfaces.

29. An optical device above to collect light, including light from a substantially uncollimated, incoherent source and selectively outputting the light, comprising:

a first layer having an optical index of refraction n₁, said first layer having a top layer surface converging toward a bottom layer surface and an input surface spanning said top and bottom surfaces to define an input end surface forming the larger thickness end of said first layer;

an air gap layer underlying at least said bottom surface of said first layer creating a critical angle of incidence θ

_c for the light in said first layer characteristic of the interface between said bottom layer surface and said air gap thereby causing the light to enter said air gap layer upon the light being reflected in said first layer decreasing its angle of reflection relative to a normal to at least one of said top and bottom surfaces to reach an angle of reflection less than the critical angle θ

_c relative to the normal; and

light reflecting means underlying said air gap layer for reflecting light received from said first layer through said air gap, said light reflecting means cooperating with said first layer and said air gap to form a beam of light for output into ambient over a controlled angular distribution.

30. The optical device as defined in claim 29 further including a light redirecting means disposed adjacent at least one of (a) said top wedge surface and (b) said input end surface with said light redirecting means of said input end surface comprised of means for at least filling the numerical aperture of said first layer.

31. The optical device as defined in claim 30 wherein said light redirecting means comprises a faceted portion.

32. The optical device as defined in claim 31 wherein said faceted portion includes a plurality of facets having at least one of (a) facets including progressively varied facet angles such that said plurality of facets form a layer comprising a section of a Fresnel parabola and/or a Fresnel cylinder, (b) each of said facets constructed to produce a desired light cone of particular angular distribution and (c) each of said facets constructed of selectable flat and curved facet face geometry.

33. The optical device as defined in claim 29 wherein said beam of controlled angular distribution is spread over an angle within about ±

30°

from the average angle of output from said top layer surface.

34. The optical device as defined in claim 29 wherein said device comprises at least a portion of a wedge like disk having a central longitudinal passage for receiving said light source.

35. An optical device capable of collecting light, including a substantially uncollimated, incoherent light from a source and selectively outputting the light, comprising:

a first layer having an optical index of refraction n₁, said first layer having a back surface and converging top and bottom layer surfaces positioned adjacent a gas containing gap with an optical index of refraction n₂ and light input through said back surface of said first layer entering said gap when the light being reflected in said first layer decreases its angle of reflection relative to a normal to said bottom surface to achieve an angle of reflection less than the critical angle of incidence θ

_c, relative to the normal, characteristic of the interface between said bottom layer surface and said gas containing gap; and

light redirecting means underlying said gas containing gap, said light redirecting means for selectively reflecting light output from the first layer and outputting the light from said top layer surface, said light redirecting means further adapted to include means for focusing light output from said first layer.

36. The optical device as defined in claim 35 wherein said focusing means comprises at least one of a curved light redirecting means and a faceted portion having a particular facet angularity for providing a particular selected focusing.

37. The optical device as defined in claim 36 wherein said focusing means is configured to focus light from the end portions of said top layer surface to the central angle of light output from said top layer surface.

38. The optical device as defined in claim 36 wherein facets of said faceted portion comprise different angles of inclination for the facets on extreme ends of said focusing means.

39. The optical device as defined in claim 36 wherein said focusing means is constructed to control overlap of light output from different portions of said focusing means.

40. The optical device as defined in claim 36 wherein said faceted portion comprises facets providing at least one of (a) increased light overlap at selected viewing distances, (b) light overlap to form a preferred viewing output distribution, (c) particular facet angularity for providing a particular focusing and (d) different focal points for each of said facets.

41. The optical device as defined in claim 35 wherein said light redirecting means includes at least two portions configured to provide overlapping light output.

42. The optical device as defined in claim 36 wherein facets of said faceted portion comprise at least one of (a) facets of different angles of inclination for at least a fraction of the face of the facets, (b) facets of different angles of inclination progressively changed along the length of said focusing means and (c) facets of different angles of inclination at extreme ends of said focusing means.

43. The optical device as defined in claim 35 wherein said first layer includes a nonlinearly varying thickness near said back surface for at least one of controlling the uniformity of light output into ambient from said optical device and for optically compensating for the nonuniformity of the light input to said first layer.

44. The optical device as defined in claim 35 further including an overlying light redirecting layer and an overlying liquid crystal display operable with ambient light.

45. The optical device as defined in claim 35 further including a diffuser layer at least one of (a) disposed between said source of light and said first layer, (b) overlying said first layer and (c) disposed below said light redirecting means.

46. The optical device as defined in claim 45 wherein said diffuser layer comprises at least one of (a) a focusing layer (b) a translucent layer and (c) a lenticular array.

47. The optical device as defined in claim 35 wherein said source of light comprises a compound parabolic concentrator source.

48. The optical device as defined in claim 35 further including at least one additional layer disposed between at least one of (a) said first layer and said gas containing gap and (b) said gas containing gap and said light redirecting means.

49. The optical device as defined in claim 35 wherein said optical device is operable as a concentrator with light being input into at least one of said first layer and said light redirecting means and output from said back surface for collection.

50. An optical device for collecting light, including a substantially uncollimated, incoherent light from a source and outputting the light, comprising:

a first layer having a wedge shaped cross sectional area with an optical index of refraction n₁, said layer having a back surface and a converging top and bottom surface with at least one angle of convergence φ

;

a second layer with an optical index of refraction n₂ and light being input through said back surface of said first layer entering said second layer when the light being reflected in said first layer decreases its angle of reflection relative to a normal to said bottom surface to achieve an angle of reflection less than the critical angle of incidence θ

_c relative to the normal with said bottom layer surface, characteristic of the interface between said bottom layer surface and said second layer; and

third layer means disposed adjacent said second layer acting cooperatively with said first and second layer to control angular distribution of the light of said optical device and for outputting the light from said top layer surface.

51. The optical device as defined in claim 50 wherein said first layer has a plurality of angles φ

, thereby enabling control of light output.

52. The optical device as defined in claim 50 wherein said third layer means includes portions of varying curvature to output light over a preferred viewing area.

53. The optical device as defined in claim 50 wherein said third layer means portion includes at least one of (a) an individual facet, (b) a plurality of facets, (c) faceted portions disposed adjacent one another, (d) facets having a small focal point and (e) facets having their focus over a viewing area.

54. An optical device for collecting light from a source and for selectively outputting light, comprising:

a first layer capable of receiving light from said source and having an optical index of refraction n₁ and top and bottom layer surfaces converging to define at least one angle of inclination φ

, said first layer including a back surface spanning said top and bottom layer surfaces and the light exiting said first layer when the light being reflected therein decreases its angle of reflection relative to a normal to said top and bottom layer surfaces and achieves an angle of reflection less than the critical angle θ

_c relative to the normal;

layer means including a first and second intermediate layer underlying said bottom layer surface and said top layer surface, respectively, and having an effective optical index of refraction n_2a and n_2b, respectively, for allowing transmission of light output from said first layer; and

light redirecting means underlying said layer means, at least one of said redirecting means allowing transmission of light across the thickness of said redirecting means for selectively redirecting light output from said layer means.

55. The optical device as defined in claim 54 wherein said indices n_2a and n_2b have the following relationship with the angle of inclination φ

;

space="preserve" listing-type="equation">|arcsin (n.sub.2a /n.sub.1)-arcsin (n.sub.2b /n.sub.1)|<

φ

56. The optical device as defined in claim 54 further including a diffuser layer disposed adjacent said light redirecting means for modifying the light output from said light redirecting means.

57. The optical device as defined in claim 56 wherein said diffuser layer comprises at least one of a lenticular diffuser, a volume diffuser and a surface diffuser.

58. The optical device as defined in claim 54 wherein said first and second intermediate layer comprise at least one of a gaseous gap layer and a transparent material having n₂ 21 n.sub..

59. The optical device as defined in claim 58 wherein said transparent material is selected from the group consisting of sol-gels, fluoropolymers, fluoride salts, silicones and adhesives.

60. The optical device as defined in claim 54 further including a reflective layer disposed on the ambient side of said light redirecting means.

61. The optical device as defined in claim 60 wherein said reflective layer comprises at least one of a planar specular reflector, a diffuse reflector and a faceted reflector.

62. The optical device as defined in claim 54 wherein at least one of said redirecting layer comprises a transparent right angle film.

63. An optical device for collecting light and selectively outputting the light to a viewer comprising:

a light source;

a first layer capable of receiving light from said source and having an optical index of refraction n₁ and top and bottom layer surfaces converging to define at least one angle of inclination φ

, said first layer including a back surface spanning said top and bottom layer surfaces and the light exiting said first layer when the light being reflected therein increases its angle of reflection relative to a normal to said top and bottom layer surfaces and achieves an angle of reflection less than the critical angle θ

_c relative to the normal;

layer means underlying said first layer having an optical index of refraction n₂ ; and

a light redirecting layer disposed at least one of (a) overlying said first layer and (b) underlying said layer means, said light redirecting layer allowing transmission of light there across and further including facets whose angles of orientation can be constructed to vary across a planar dimension of said redirecting layer to control the angular output range of substantially uniform intensity as seen by the viewer.

64. The optical device as defined in claim 63 wherein said light redirecting layer comprises a layer of facets having changing facet angle across at least one of the planar width and length of said redirecting layer.

65. The optical device as defined in claim 63 wherein said light redirecting layer comprises a layer of facets disposed on at least one of a semi-cylindrical surface of radius R and a parabolic surface of focal length F, thereby causing changes of said angles of orientation of the surface of said facets.

66. The optical device as defined in claim 63 wherein said light redirecting layer comprises an underlying back reflector layer.

67. The optical device as defined in claim 63 wherein said light redirecting layer comprises an overlying faceted light redirecting layer.

68. The optical device as defined in claim 63 wherein said light redirecting layer comprises two of said layers comprised of at least one of (a) a diffraction grating and a hologram, (b) two faceted layers and selectively a lenticular diffuser, (c) two faceted layers with facets designed to refract and internally reflect light output from said first layer, (d) two refracting single facet layers;

(e) a top surface refracting single facet layer with curved output surface and a bottom surface refracting/internally reflecting faceted layer, (f) a top surface refracting faceted layer and a bottom surface refracting/internally reflecting layer, (g) a top surface and bottom surface refracting/internally reflecting faceted layer and (h) a top surface refracting faceted layer and a bottom surface refracting/internally reflecting faceted layer.

69. The optical device as defined in claim 63 wherein said light redirecting layer comprises a transmissive and a reflective light redirecting layer, said layers comprised of at least one of the combination of layers (a) a bottom specular reflector and a top layer transmission diffraction grating or a transmission hologram, (b) a bottom specular reflector and a top layer refracting faceted layer, (c) a bottom specular reflector and a top layer refracting/internally reflecting faceted layer, (d) a bottom specular reflector and a top layer refracting/internally reflecting faceted layer, (e) a bottom reflector which is partially specular and partial diffuse transmitter and a top redirecting layer which is refracting/reflecting with curved reflecting surface, (f) a bottom reflector which is partially specular, partially diffuse and a top redirecting layer of refracting/internally reflecting flat faceted layer.