Thermally switched optical filter incorporating a guest-host architecture

• US 8,284,336 B2
• Filed: 04/12/2010
• Issued: 10/09/2012
• Est. Priority Date: 04/10/2009
• Status: Expired due to Fees

• Current Assignee: Ravenbrick, LLC
• Original Assignee: Ravenbrick, LLC
• Inventors: Powers, Richard M., McCarthy, Wil
• Primary Examiner(s): Healy, Brian
• Application Number:
  US12/758,573
• Publication Number:
  US 20100259698A1
• Time in Patent Office: 911 Days
• Field of Search: 349/20, 349/19, 349/56, 349/104, 349/112, 349/113, 349/115, 349/116, 349/201, 359/265, 359/266, 359/267, 359/272, 359/288
• US Class Current: 349/20
• CPC Class Codes: C09K 19/02 characterised by optical, electrical or physical properties of the components, in general
• CPC Class Codes: C09K 2219/13 used in the technical field of thermotropic switches
• CPC Class Codes: E06B 2009/2464 featuring transparency control by applying voltage, e.g. LCD, electrochromic panels
• CPC Class Codes: E06B 9/24 Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blindsoperating, guiding or securing devices or arrangements for roll-type closures E06B9/56; free-hanging flexible screens A47H23/00
• CPC Class Codes: G02B 26/004 based on a displacement or a deformation of a fluid
• CPC Class Codes: G02B 26/007 the movable or deformable optical element controlling the colour, i.e. a spectral characteristic, of the light
• CPC Class Codes: G02F 1/0126 Opto-optical modulation, i.e. control of one light beam by another light beam, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/132 Thermal activation of liquid crystals exhibiting a thermo-optic effect
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence

Abstract

Thermochromic filters are constructed using absorptive, reflective, or fluorescent dyes, molecules, polymers, particles, rods, or other orientation-dependent colorants that have their orientation, order, or director influenced by carrier materials, which are themselves influenced by temperature. These order-influencing carrier materials include thermotropic liquid crystals, which provide orientation to dyes and polymers in a Guest-Host system in the liquid-crystalline state at lower temperatures, but do not provide such order in the isotropic state at higher temperatures. The varying degree to which the absorptive, reflective, or fluorescent particles interact with light in the two states can be exploited to make many varieties of thermochromic filters. Thermochromic filters can control the flow of light and radiant heat through selective reflection, transmission, absorption, and/or re-emission. The filters have particular application in passive or active light-regulating and temperature-regulating films, materials, and devices, and particularly as construction materials and building and vehicle surfaces.

Claims

1. A thermochromic filter device comprising

an order-providing, thermotropic carrier material defining a director orientation;

and

an orientation-dependent colorant material included within the thermotropic carrier material responsive in order to the director orientation;

wherein

the director orientation of the thermotropic carrier material is responsive to temperature-induced changes in the thermotropic carrier material;

the orientation-dependent colorant material changes orientation with the director orientation, whereby light transmission properties of the device vary with temperature as a result.

2. The device of claim 1, wherein the orientation-dependent colorant material is reflective.

3. The device of claim 2, wherein the reflectivity of the orientation-dependent colorant material is partially or completely diffusive.

4. The device of claim 3, wherein the thermochromic filter device both transmits light specularly and reflects light partially or completely diffusively.

5. The device of claim 1, wherein the orientation-dependent colorant material is absorptive.

6. The device of claim 1, wherein the orientation-dependent colorant material is fluorescent.

7. The device of claim 1, wherein the orientation-dependent colorant material is a dye.

8. The device of claim 1, wherein the orientation-dependent colorant material is electrically conductive.

9. The device of claim 8, wherein the orientation-dependent colorant material is a conductive polymer.

10. The device of claim 8 further comprising an electrical override acting on the orientation-dependent colorant materials.

11. The device of claim 1 further comprising an electrical override system acting on the order-providing carrier material.

12. The device of claim 1 further comprising a polymer or a polymer network, and wherein

the orientation-dependent colorant materials are attached to, constrained by, or the director orientation is influenced by, the polymer or the polymer network.

13. The device of claim 1, wherein the order-providing carrier material is a thermotropic liquid crystal.

14. The device of claim 1, wherein a substrate, or chemicals, materials, or features on a surface of the substrate, influence director orientation of the order-providing thermotropic carrier material.

15. The device of claim 14, wherein the order-providing carrier material is a thermotropic liquid crystal.

16. The device of claim 14, wherein the substrate is a polymer.

17. The device of claim 1, wherein the order-providing, thermotropic carrier material is contained in, or attached to, a flexible substrate.

18. The device of claim 17, wherein the flexible substrate is a polymer.

19. The device of claim 1, wherein the orientation-dependent colorant materials are a combination of reflective, absorptive, and/or fluorescent materials.

20. The device of claim 1, wherein the orientation-dependent colorant materials are selected for desired aesthetic transmission or reflection properties, including hue and intensity, at one or more temperatures.

21. The device of claim 1, wherein the orientation-dependent colorant materials are selected to interact with specific wavelengths or bandwidths of light at one or more temperatures.

22. The device of claim 1 further comprising a polarizer.

23. The device of claim 22, wherein the polarizer is a polarity-rotating polarizer.

24. The device of claim 1, wherein the orientation of the orientation-dependent colorant materials polarizes incident light.

25. The device claim 24, wherein the orientation-dependent colorant materials are selected for polarizing properties that vary with the direction of light received at the device.

26. The device of claim 24, wherein a transition temperature from an ordered (polarizing or more polarizing) state to a less ordered (nonpolarizing or less polarizing) state occurs either above, within, or below a normal operating temperature range of a window, wall, or related component in a building, vehicle, or other structure.

27. The device of claim 1, wherein a transition temperature from an ordered (transmissive) state to a less ordered (blocking) state occurs either above, within, or below a normal operating temperature range of a window, wall, or related component in a building, vehicle, or other structure.

28. The device of claim 1, wherein the orientation-dependent colorant material operates in one or more of visible wavelengths, infrared wavelengths, or ultraviolet wavelengths.

29. The device of claim 28, wherein visible, ultraviolet, and infrared transmission, reflection, and absorption properties of the orientation-dependent colorant materials are selected for dynamic solar heat gain control.

30. The device of claim 1, wherein the orientation-dependent colorant material operates in a combination of ultraviolet, visible, and/or infrared wavelengths.

31. The device of claim 1, wherein the order-providing, thermotropic carrier material and the orientation-dependent material are selected to result in a difference in optical index between the order-providing, thermotropic carrier material and the orientation-dependent material to thereby affect the light transmission properties of the device.

32. The device of claim 1, wherein the thermotropic carrier material is selected for birefringent properties utilized to affect the light transmission properties of the device.

33. A thermochromic filter device comprising

an order-providing, thermotropic host material;

and

an orientation-dependent colorant guest material included within the thermotropic host material responsive in order to an orientation of the host material;

wherein

the orientation of the thermotropic host material is responsive to temperature-induced changes in the thermotropic host material;

the orientation-dependent colorant material changes orientation with the orientation of the thermotropic host material, whereby light transmission properties of the device vary with temperature as a result.