THERMALLY SWITCHED OPTICAL DOWNCONVERTING FILTER

• US 20080210893A1
• Filed: 01/24/2008
• Published: 09/04/2008
• Est. Priority Date: 01/24/2007
• Status: Active Grant

• Current Assignee: Ravenbrick, LLC
• Original Assignee: Ravenbrick, LLC
• Inventors: Powers, Richard M., McCarthy, Wil
• Granted Patent: US 7,768,693 B2
• Time in Patent Office: Days
• US Class Current: 250/517.1
• CPC Class Codes: C03C 17/23 Oxides C03C17/02 takes precedence
• CPC Class Codes: C03C 2217/218 V2O5, Nb2O5, Ta2O5
• CPC Class Codes: C03C 2217/219 CrOx, MoOx, WOx
• CPC Class Codes: C03C 2217/23 Mixtures
• CPC Class Codes: G02B 5/0289 used as a transflector
• CPC Class Codes: G02B 5/223 containing organic substances, e.g. dyes, inks or pigments
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 2/02 Frequency-changing of light, e.g. by quantum counters

Abstract

A thermally switched optical downconverting (TSOD) filter is a self-regulating device including a downconverter that converts incoming light at a variety of wavelengths into longer-wavelength radiation and then directs it using one or more bandblock filters in either the inward or outward direction, depending on the temperature of the device. This control over the flow of radiant energy occurs independently of the thermal conductivity or insulating properties of the device and may or may not preserve the image and color properties of incoming visible light. The TSOD filter has energy-efficiency implications, as it can be used to regulate the internal temperature and illumination of buildings, vehicles, and other structures without the need for an external power supply or operator signals. The TSOD filter also has aesthetic implications, since the device has unique optical properties that are not found in traditional windows, skylights, stained glass, light fixtures, glass blocks, bricks, or walls. The TSOD filter has particular, but not exclusive, application as a building material.

Claims

1. A thermally switched optical filter comprising

a substrate;

a downconverter supported by the substrate, wherein the downconverter absorbs incident light of a broad bandwidth and emits light at an emission wavelength substantially or entirely longer than wavelengths of the broad bandwidth; and

a first bandblock filter supported by the substrate, wherein the first bandblock filter blocks the emitted light when the temperature of the thermally switched optical filter is in a first range and passes the emitted light when the temperature of the thermally switched optical filter is in a second range.

2. The thermally switched optical filter of claim 1 further comprising

an outer surface that receives the incident light;

and

an inner surface, wherein

when the first range temperature is a low temperature compared to the second range, the emitted light exits the thermally switched optical filter from the inner surface.

3. The thermally switched optical filter of claim 1 further comprising

an outer surface that receives the incident light;

and

an inner surface, wherein

when the first range is a high temperature compared to the second range, the emitted light exits the thermally switched optical filter from the outer surface.

4. The thermally switched optical filter of claim 1 further comprising

an outer surface that receives the incident light;

and

an inner surface, wherein

when the temperature of the thermally switched optical filter is between the first range and the second range, the emitted light exits the thermally switched optical filter from both the inner surface and the outer surface.

5. The thermally switched optical filter of claim 1 further comprising

a second bandblock filter supported by the substrate, wherein the second bandblock filter passes the emitted light when the temperature of the thermally switched optical filter is in the first range and blocks the emitted light when the temperature of the thermally switched optical filter is in the second range.

6. The thermally switched optical filter of claim 5 further comprising

an outer surface that receives the incident light;

and

an inner surface, wherein

when the first range is a low temperature compared to the second range, the emitted light exits the thermally switched optical filter from the inner surface.

7. The thermally switched optical filter of claim 5 further comprising

an outer surface that receives the incident light;

and

an inner surface, wherein

when the first range is a high temperature compared to the second range, the emitted light exits the thermally switched optical filter from the outer surface.

8. The thermally switched optical filter of claim 5 further comprising

an outer surface that receives the incident light;

and

an inner surface, wherein

when the temperature of the thermally switched optical filter is between the first range and the second range, the emitted light exits the thermally switched optical filter from both the inner surface and the outer surface.

9. The thermally switched optical filter of claim 5 further comprising

a longpass filter supported by the substrate, wherein the longpass filter passes the emitted light when the temperature of the thermally switched optical filter is in the first range and blocks the emitted light when the temperature of the thermally switched optical filter is in the second range.

10. The thermally switched optical filter of claim 1, wherein the downconverter is a blackbody radiator.

11. The thermally switched optical filter of claim 1, wherein the downconverter is a fluorescent, phosphorescent, or photoluminescent material.

12. The thermally switched optical filter of claim 1, wherein the downconverter comprises a plurality of quantum confinement devices embedded in a transparent material.

13. The thermally switched optical filter of claim 1, wherein the downconverter defines openings through which the incident light passes without absorption.

14. The thermally switched optical filter of claim 1, wherein the substrate is transparent.

15. The thermally switched optical filter of claim 1, wherein the downconverter is thermochromic and the emission wavelength is variable depending upon a temperature of the downconverter.

16. The thermally switched optical filter of claim 1, wherein the first bandblock filter is thermochromic.

17. The thermally switched optical filter of claim 6, wherein each of the first bandblock filter and the second bandblock filter is thermochromic.

18. The thermally switched optical filter of claim 1, wherein the emission wavelength of the downconverter occurs in the visible spectrum.

19. The thermally switched optical filter of claim 1, wherein the emission wavelength of the downconverter occurs in the infrared spectrum.

20. The thermally switched optical filter of claim device of claim 1, wherein the emission wavelength of the downconverter is selected for optimal catalysis of a chemical reaction or a particular optical effect.

21. The thermally switched optical filter of claim 1, wherein the substrate is a flexible fabric or polymer sheet.

22. The thermally switched optical filter of claim 1, wherein the substrate is glass or a transparent or translucent rigid polymer material.

23. The thermally switched optical filter of claim 1 further comprising an external reflector that is positioned to direct the incident light toward an outer surface of the thermally switched optical filter.

24. The thermally switched optical filter of claim 1 further comprising a plurality of fins positioned at an angle to an outer surface of the thermally switched optical filter partially restrict, block, absorb, reflect, or attenuate the incident light from reaching the outer surface.

25. The thermally switched optical filter of claim 1 further comprising an attenuator that blocks a percentage of the incident light across the broad bandwidth.

26. The thermally switched optical filter of claim 25, wherein the attenuator comprises a thermochromic or thermotropic liquid crystal device.

27. The thermally switched optical filter of claim 25, wherein the attenuator comprises a thermochromic, optically reflective material.

28. The thermally switched optical filter of claim 25, wherein the attenuator comprises a thermochromic, infrared reflective material.

29. The thermally switched optical filter of claim 27 further comprising

a control system;

a power supply connected with the control system and the attenuator; and

one or more sensors connected with the control system;

wherein

the attenuator further comprises an electrochromic material that is activated by the control system based upon feedback from the sensors to pass or block the incident light from reaching the downconverter.

30. The thermally switched optical filter of claim 27 further comprising

a control system;

a power supply connected with the control system and the downconverter; and

one or more sensors connected with the control system;

wherein

the downconverter further comprises an electrochromic material that is activated by the control system based upon feedback from the sensors to alter the emission wavelength of the emitted light.

31. The thermally switched optical filter of claim 1 further comprising a collimator that orients the incident light toward an outer surface of the thermally switched optical filter.

32. The thermally switched optical filter of claim 1 further comprising a concentrating lens that focuses the incident light on an outer surface of the thermally switched optical filter.

33. The thermally switched optical filter of claim 32 further comprising a diffuser or de-concentrating lens that disperses an intensity of the emitted light from the thermally switched optical filter.

34. The thermally switched optical filter of claim 1 further comprising a color filter overlaying one or both of an inner surface or an outer surface of the thermally switched optical filter.

35. The thermally switched optical filter of claim 1 further comprising an antireflective coating overlaying one or both of an inner surface or an outer surface of the thermally switched optical filter.

36. The thermally switched optical filter of claim 1 further comprising a thermal insulation layer supported by the substrate.

37. The thermally switched optical filter of claim 36, wherein the thermal insulation layer further comprises an air gap.

38. The thermally switched optical filter of claim 1 further comprising a broadband reflector that reflects the emitted light internally within the thermally switched optical filter.

39. The thermally switched optical filter of claim 1 further comprising an energy storage material supported by the substrate.

40. A thermally switched optical filter comprising

a first bandblock filter layer;

a second bandblock filter layer;

a thermochromic downconverter layer sandwiched between the first bandblock filter layer and the second bandblock filter layer, wherein

the downconverter layer absorbs incident light of a broad bandwidth and emits light at an emission wavelength substantially or entirely longer than wavelengths of the broad bandwidth, and

the emission wavelength is variable depending upon a temperature of the downconverter layer; and

a transparent substrate supporting the first bandblock filter layer, the second bandblock filter layer, and the thermochromic downconverter layer;

wherein

the first bandblock filter layer blocks the emitted light when the temperature of the downconverter layer is below a first threshold temperature and passes the emitted light when the temperature of the downconverter layer is above a second threshold temperature; and

the second bandblock filter layer passes the emitted light when the temperature of the downconverter layer is below the first threshold temperature and blocks the emitted light when the temperature of the downconverter layer is above the second threshold temperature.

41. The thermally switched optical filter of claim 40, wherein the emission wavelength of the downconverter occurs in the visible spectrum.

42. The thermally switched optical filter of claim 40, wherein the emission wavelength of the downconverter occurs in the infrared spectrum.

43. A spandrel comprising the thermally switched optical filter of claim 40.

44. A window comprising the thermally switched optical filter of claim 40.

45. A spandrel comprising

a pane of glass that forms an exterior plate of the spandrel;

a first thermochromic attenuator overlaying an interior surface of the glass pane;

a nonreflective plate adjacent the thermochromic attenuator that absorbs incident light passing through the glass pane and the attenuator and downconverts the incident light and emits light at an emission wavelength;

a transparent insulating layer between the thermochromic attenuator and the nonreflective plate;

a first low emissivity coating on an exterior surface of the nonreflective plate;

a backplate forming an interior plate of the spandrel adjacent to and spaced apart from the nonreflective plate; and

an energy storing material sandwiched between the nonreflective plate and the backplate.

46. The spandrel of claim 45 further comprising a second low emissivity coating on an interior surface of the thermochromic attenuator.

47. The spandrel of claim 45, wherein the transparent insulating layer is an air gap.

48. The spandrel of claim 45, wherein the nonreflective plate is painted black.

49. The spandrel of claim 45, wherein the thermochromic attenuator comprises a liquid crystal plate.

50. The spandrel of claim 45, wherein the thermochromic attenuator comprises a film of a thermochromic, optically reflective material.

51. The spandrel of claim 45, wherein the thermochromic attenuator comprises a film of a thermochromic, infrared reflective material.

52. The spandrel of claim 45 further comprising a second thermochromic attenuator positioned between the transparent insulating layer and the low emissivity coating.

53. The spandrel of claim 45 wherein the second thermochromic attenuator has a higher transition temperature than the first thermochromic attenuator.

54. The spandrel of claim 45, wherein the backplate comprises a sheet of glass, plastic, or metal.

55. The spandrel of claim 45 further comprising an aesthetic surface treatment applied to an interior side of the backplate.

56. The spandrel of claim 45, wherein the energy storing material comprises a phase change material.

57. The spandrel of claim 56, wherein the phase change material comprises one or more of a wax or salt.

58. A window comprising

a first pane of glass;

a first low emissivity coating on a surface of the first glass pane;

a thermochromic downconverter film supported by the first glass pane, wherein

the thermochromic downconverter film absorbs incident light of a broad bandwidth and emits light at an emission wavelength substantially or entirely longer than wavelengths of the broad bandwidth, and

the emission wavelength is variable depending upon a temperature of the downconverter layer; and

the first low emissivity coating blocks the emitted light when a temperature of the window is in a first range and passes the emitted light when the temperature of the window is in a second range.

59. The window of claim 58 further comprising a second low emissivity coating on the thermochromic downconverter film on an opposite side of the thermochromic downconverter film than the first low emissivity coating.

60. The window of claim 58 further comprising

a second low emissivity coating on the thermochromic downconverter film on an opposite side of the thermochromic downconverter film than the first low emissivity coating;

a second pane of glass spaced apart from the thermochromic downconverter film; and

a transparent insulating layer sandwiched between the second glass pane and the thermochromic downconverter film.

61. The window of claim 60, wherein the transparent insulating layer is an air gap.

62. The window of claim 60, wherein

the first low emissivity coating blocks the emitted light when the temperature of the thermochromic downconverter film is below a first threshold temperature and passes the emitted light when the temperature of the thermochromic downconverter film is above a second threshold temperature;

and

the second low emissivity coating passes the emitted light when the temperature of the thermochromic downconverter film is below the first threshold temperature and blocks the emitted light when the temperature of the thermochromic downconverter film is above the second threshold temperature.

63. The window of claim 58 further comprising

a second pane of glass spaced apart from the thermochromic downconverter layer;

a second low emissivity coating on the second glass pane; and

a transparent insulating layer sandwiched between the second glass pane and the first low emissivity coating.

64. The window of claim 63, wherein the transparent insulating layer is an air gap.

65. The window of claim 63, wherein

the first low emissivity coating blocks the emitted light when the temperature of the thermochromic downconverter film is below a first threshold temperature and passes the emitted light when the temperature of the thermochromic downconverter film is above a second threshold temperature;

and

the second low emissivity coating passes the emitted light when the temperature of the thermochromic downconverter film is below the first threshold temperature and blocks the emitted light when the temperature of the thermochromic downconverter film is above the second threshold temperature.

66. The window of claim 58 further comprising a thermochromic attenuator supported by the first glass pane.

67. The window of claim 66, wherein the thermochromic attenuator is positioned between the first glass pane and the first low emissivity coating whereby the first low emissivity coating covers a surface of the thermochromic attenuator instead of the surface of the first glass pane.

68. The window of claim 66, wherein the thermochromic attenuator comprises a liquid crystal plate.

69. The window of claim 66, wherein the thermochromic attenuator comprises a film of a thermochromic, optically reflective material.

70. The window of claim 66, wherein the thermochromic attenuator comprises a film of a thermochromic, infrared reflective material.

71. The window of claim 58, wherein the thermochromic downconverter film defines a plurality of transparent openings.

72. A method for regulating the flow of light and radiant heat comprising

absorbing incident light at multiple wavelengths with a downconverter;

emitting the incident light from the downconverter at an emission wavelength substantially or entirely longer than the wavelengths of the incident light; and

reflecting the emitted light with one or more bandblock filters, wherein

the emitted light escapes in an inward direction when an ambient temperature is in a first range;

the emitted light escapes in an outward direction when the ambient temperature is in a second range; and

the emitted light escapes in both the inward direction and the outward direction when the ambient temperature is between the first range and the second range.

73. The method of claim 72 further comprising passively and selectively passing and blocking the incident light with a thermochromic attenuator based upon the ambient temperature.

74. A method for regulating the temperature of a building comprising

cladding an exterior surface of at least a portion of the building with a layered material comprising a downconverter layer and one or more bandblock filters;

absorbing incident light at multiple wavelengths within the downconverter layer;

emitting the incident light from the downconverter layer at an infrared wavelength; and

reflecting the emitted light with one or more bandblock filters, wherein

the emitted light escapes in an inward direction when an ambient temperature is below a first threshold temperature;

the emitted light escapes in an outward direction when the ambient temperature is above a second threshold temperature; and

the emitted light escapes in both the inward direction and the outward direction when the ambient temperature is between the first threshold temperature and the second threshold temperature.

75. The method of claim 74, wherein the cladding further comprises a thermochromic attenuator layer and the method further comprises passively and selectively passing and blocking the incident light with the thermochromic attenuator layer based upon the ambient temperature.