Totally internally reflecting light conduit

• US 4,805,984 A
• Filed: 09/05/1986
• Issued: 02/21/1989
• Est. Priority Date: 11/21/1985
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Company
• Inventors: Cobb, Sanford Jr.
• Primary Examiner(s): Lee, John D.
• Assistant Examiner(s): Heartney, Phan
• Application Number:
  US06/903,657
• Time in Patent Office: 900 Days
• Field of Search: 350/96.10, 350/96.24, 350/96.27, 350/96.28, 350/96.29, 350/96.30, 350/96.34, 350/259, 350/262, 350/264, 350/265
• US Class Current: 385/133
• CPC Class Codes: F21V 2200/40 of hollow light guides
• CPC Class Codes: F21V 5/002 using microoptical elements for redirecting or diffusing light
• CPC Class Codes: G02B 5/12 Reflex reflectors
• CPC Class Codes: G02B 6/0096 the lights guides being of the hollow type
• CPC Class Codes: G02B 6/032 with non solid core or cladding G02B6/02295 takes precedence
• CPC Class Codes: G02B 6/10 of the optical waveguide type G02B6/02, G02B6/24 take precedence; devices or arrangements for the control of light by electric, magnetic, electro-magnetic or acoustic means G02F1/00; transferring the modulation of modulated light G02F2/00; optical logic elements G02F3/00; optical analogue/digital converters G02F7/00
• CPC Class Codes: G02B 6/24 Coupling light guides
• CPC Class Codes: G02B 6/3807 Dismountable connectors, i.e. comprising plugs

Abstract

A hollow, tubular light conduit including a wall of a transparent polymeric material, and the wall having a structured surface and an opposite, smooth, glossy surface, and at least a portion of the cross-section of the wall lying in a smooth arcuate curve, wherein light striking the inner surface, within an acceptable angular range, is contained by total internal reflection. The structured surface includes a linear array of substantially right angled isosceles prisms arranged side-by-side to form grooves. In addition, the perpendicular sides of the prisms make an angle of approximately 45° with the tangent to the smooth surface. Because of the flexibility of the light conduit and its ability to totally internally reflect light, a manipulated light conduit may be utilized in a variety of ways, for example, as a light fixture whereby some of the light directed into the light conduit is emitted from the light conduit for illumination or for use as a secondary light source. A suitable light source may include artificial or solar energy. However, when the light fixture operates as a warning light it is preferred that a strobe light be used.

Claims

1. A hollow, tubular light conduit for transporting light there along and/or distributing light therefrom, comprising a wall member of a transparent material, said wall member including a structured surface on one side and a smooth surface opposite said structured surface on the other side, at least a portion of the cross-section of said wall member lying in a smooth arcuate curve, said structured surface having a linear array of substantially right angled isosceles prisms arranged side-by-side, the perpendicular sides of said prisms making an angle of approximately 45°

with the tangent to said smooth surface opposite said structured surface, so that a predetermined portion of the light entering the light conduit within an acceptable angular range, is contained by total internal reflection as it travels along the length of the light conduit.

2. The light conduit defined in claim 1 wherein said wall member is substantially circular in cross-section.

3. The light conduit defined in claim 2 wherein said smooth surface is disposed on the inner side of said wall member and incident light striking said smooth surface within an acceptable angular range is totally internally reflected, and said prisms run parallel to the axis of said wall member.

4. The light conduit defined in claim 2 wherein said structured surface is disposed on the inner side of said wall member and incident light striking said structured surface within an acceptable angular range is totally internally reflected, and said prisms run parallel to the axis of said wall member.

5. The light conduit defined in claim 1 wherein said wall member is substantially elliptical in cross-section.

6. The light conduit defined in claim 1 wherein said transparent material is a polymeric material.

7. The light conduit defined in claim 1 further comprising performance manipulating means associated with said wall member for allowing some of the light to be emitted from said light conduit through said wall member without being totally internally reflected.

8. The light conduit defined in claim 7 wherein said performance manipulating means includes non-optically sharp corners of said prisms.

9. The light conduit defined in claim 7 wherein said performance manipulating means includes non-optically smooth surfaces of said wall member.

10. A light fixture, comprising:

a housing having an inner surface and an outer surface;

a hollow, tubular light conduit contained within said housing including a wall member of a transparent material, said wall member having a structured surface on one side and a smooth surface opposite said structured surface on the other side, and at least a portion of the cross-section of said wall member lying in a smooth arcuate curve, said structured surface having a linear array of substantially right angled isosceles prisms arranged side-by-side, the perpendicular sides of said prisms making an angle of approximately 45°

with the tangent to said smooth surface opposite said structured surface;

performance manipulating means associated with said wall member for allowing light to be emitted from said light conduit through said wall member without being contained within said light fixture by total internal reflection;

optical window means in said housing for allowing the emission of light from said light conduit through said optical window means; and

light source means associated with said light conduit for supplying light into said light conduit so that light entering said light conduit may be emitted from said light conduit and may thereby exit from said light fixture through said optical window means.

11. The light fixture defined in claim 10 wherein said transparent material is a polymeric material.

12. The light fixture defined in claim 10 wherein said hollow, tubular light conduit is substantially circular in cross-section.

13. The light fixture defined in claim 10 further comprising diffuser means associated with said optical window means for dispersing the light exiting said light conduit through said optical window in a desired fashion.

14. The light fixture defined in claim 10 wherein said light source means includes means for collecting and directing solar energy into said light conduit.

15. The light fixture defined in claim 10 wherein said light source means includes a source of artificial light.

16. The light fixture defined in claim 15 wherein said source of artificial light is a strobe light which is associated with one end of said light conduit.

17. The light fixture defined in claim 16 further comprising reflective means associated with the other end of said light conduit for reflecting light incident upon said reflective means back up said light conduit to aid in the even distribution of light through said optical window means.

18. The light fixture defined in claim 10 further comprising reflective coating means associated with the inner surface of said housing for reflecting said light emitted from said light conduit and striking said reflective coating means back through said wall member.

19. The light fixture defined in claim 10 further comprising message means associated with said optical window means for viewing, whereby said light conduit acts as a secondary light source so that said message means may be observed.

20. A light conduit, comprising:

a member including at least one open side, an inner side, an outer side and a wall of a transparent material, said wall having a structured surface on one side and a smooth surface opposite said structured surface on the other side, at least a portion of the cross-section of said wall lying in a smooth arcuate curve, said structured surface having a linear array of substantially right angled isosceles prisms arranged side-by-side, the perpendicular sides of said prisms making an angle of approximately 45°

with the tangent to said smooth surface opposite said structured surface, whereby a predetermined portion of the light entering the light conduit within an incorporating imperfections acceptable angular range is contained by total internal reflection as it travels along the length of the light conduit.

21. The light conduit defined in claim 20 further comprising reflective means associated with the open side of said channel member for redirecting light incident upon said reflective means into said channel member.

22. The light conduit defined in claim 21 wherein the transparent polymeric material forming said wall has a total thickness of 0.015 of an inch and said prisms are placed thereon between 50 to 75 prisms per inch of said wall transverse to said prisms.

23. The light conduit defined in claim 20 wherein said smooth surface is disposed on said inner side of said open channel member and incident light striking said smooth surface within an acceptable angular range is totally internally reflected.

24. The light conduit defined in claim 20 wherein said structured surface is disposed on said inner side of said open channel member and incident light striking said structured surface within an acceptable angular range is totally internally reflected.

25. The light conduit defined in claim 20 further comprising performance manipulating means associated with said wall of said open channel member for allowing light to be emitted from said light conduit through said wall without being totally internally reflected.

26. The light conduit defined in claim 25 wherein said performance manipulating means includes non-optically sharp corners of said prisms.

27. The light conduit defined in claim 25 wherein said performance manipulating means includes non-optically smooth surfaces of said wall.

28. The light conduit defined in claim 20 wherein said open channel member is generally U-shaped in cross-section.

29. The light conduit defined in claim 20 wherein said reflective means includes light diffuser means for redistributing the light in a desired fashion.

30. A warning light, comprising:

a hollow, tubular housing having an inner surface and an outer surface;

a hollow, tubular light conduit contained within said housing including a wall member of a transparent material, said wall member having a structured surface on one side and a smooth surface opposite said structured surface on the other side, said structured surface having a linear array of substantially right angled isosceles prisms arranged side-by-side, the perpendicular sides of said prisms making an angle of approximately 45°

with the tangent to said smooth surface opposite said structured surface;

optical window means in said housing for allowing the emission of light from said light conduit through said optical window means;

light source means associated with one end of said light conduit for supplying light into said light conduit so that light entering said light conduit may be emitted from said light conduit and may thereby exit from said light fixture through said optical window means.

31. The warning light defined in claim 30 wherein said light source means includes a strobe light which produces high-intensity short-duration light pulses by electric discharge in a gas.

32. The warning light defined in claim 30 wherein said hollow, tubular housing is substantially circular in cross-section, and wherein said hollow tubular light conduit is substantially circular in cross-section.

33. The warning light defined in claim 30 further comprising diffuser means associated with said optical window means for dispersing the light exiting said light conduit through said optical window in a desired fashion.

34. The warning light defined in claim 30 further comprising performance manipulating means associated with said wall member for allowing light to be emitted from said light conduit through said wall member without being contained by total internal reflection.

35. The warning light defined in claim 30 wherein said performance manipulating means includes non-optically sharp corners of said prisms to permit light leakage.

36. The warning light defined in claim 30 further comprising reflective means associated with the other end of said light conduit for reflecting light incident upon said reflective means back up said light conduit to aid in the even distribution of light through said optical window means.