Multilayer reflective films having non-linear spacing of layers

• US 6,661,486 B1
• Filed: 03/14/1998
• Issued: 12/09/2003
• Est. Priority Date: 11/27/1991
• Status: Expired due to Fees

• Current Assignee: Reveo, Inc.
• Original Assignee: Reveo, Inc.
• Inventors: Li, Le, Faris, Sadeg
• Primary Examiner(s): Ton, Toan
• Assistant Examiner(s): CHUNG, DAVID Y
• Application Number:
  US09/039,303
• Time in Patent Office: 2,096 Days
• Field of Search: 349/115, 349/194, 428/402, 428/363, 106/493, 106/31.27
• US Class Current: 349/115
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: C09B 67/0098 Organic pigments exhibiting interference colours, e.g. nacrous pigments
• CPC Class Codes: C09D 11/037 characterised by the pigment
• CPC Class Codes: C09D 11/17 characterised by colouring agents
• CPC Class Codes: C09K 19/00 Liquid crystal materials
• CPC Class Codes: C09K 19/52 characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
• 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: F24S 50/80 for controlling collection or absorption of solar radiation
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/13471 in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells G02F1/13475 takes precedence
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y10T 428/2911 Mica flake
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

A reflector for reflecting a broad bandwidth of electromagnetic (EM) radiation, comprising a sheet comprising a large plurality of pairs of layers of transparent polymer material parallel to a surface of the sheet, each pair of layers having a difference in the index of refraction between the materials in each layer of the pair, the total thickness of each pair of layers in the large plurality of layers varying substantially continuously and non linearly across the thickness of the sheet, is disclosed.

Claims

1. A reflector for reflecting a broad bandwidth of electromagnetic (EM) radiation, comprising:

a sheet comprising a large plurality of pairs of layers of transparent polymer material parallel to a surface of the sheet, each pair of layers having a difference in the index of refraction between the materials in each layer of the pair, the total thickness of each pair of layers in the large plurality of layers varying substantially continuously and non linearly across the thickness of the sheet, the sheet reflecting a broad bandwidth of the electromagnetic spectrum in the infrared portion of the electromagnetic spectrum;

an electro-optical glazing structure attached to the sheet having reflection and transmission modes of operation for selectively reflecting and transmitting electromagnetic radiation, respectively, the electro-optical glazing structure comprising;

an electro-optical glazing panel having first and second optical states of operation;

optical state switching means for switching the electro-optical panel to the first optical state of operation in order to induce the electro-optical glazing structure into the reflection mode of operation, and for switching the electro-optical panel to the second optical state of operation in order to induce the electro-optical glazing structure into the transmission to mode of operation.

2. The reflector of claim 1, further comprising a controllable scattering layer attached to the sheet.

3. The reflector of claim 1, wherein the controllable scattering layer comprises a fluid medium containing a large plurality of anisotropically shaped objects for controllably scattering light, the orientation of anisotropically shaped objects controllable by a field.

4. The reflector of claim 1, wherein the controllable scattering layer comprises a polymer medium containing a large plurality of inclusions, each inclusion containing liquid crystal material, the liquid crystal material controllable by a field.

5. The reflector of claim 1, wherein the controllable scattering layer comprises a mixture of a polymer medium and a liquid crystal material, the liquid crystal material controllable by a field.

6. A large plurality of reflecting flakes for reflecting a broad bandwidth of electromagnetic (EM) radiation, each flake comprising:

a sheet comprising a large plurality of pairs of layers of transparent polymer material parallel to a surface of the sheet, each pair of layers having a difference in the index of refraction between the materials in each layer of the pair, the total thickness of each pair of layers in the large plurality of layers varying substantially continuously and non linearly across the thickness of the sheet, wherein each flake has dimensions parallel to the surface of the sheet in the range of microns, and wherein the flakes are suspended in a transparent medium.

7. The reflector of claim 6, wherein the transparent medium is a fluid medium.

8. The reflector of claim 7, wherein the orientation of the flakes are controlled by a field, whereby the plurality of flakes transmit the EM radiation.

9. The reflector of claim 8, wherein the orientation of the flakes are controlled by field, whereby the plurality of sheets may scatter the EM radiation.

10. The reflector of claim 8, wherein the orientation of the flakes are controlled by field, whereby the plurality of flakes reflect the EM radiation in a coherent manner.

11. An electro-optical glazing structure having reflection and transmission modes of operation for selectively reflecting and transmitting a broad band of electromagnetic radiation, respectively, the electromagnetic radiation having a first and a second linear polarization, the electro-optical glazing structure comprising:

an electro-optical glazing panel having first and second optical states of operation; and

optical state switching means for switching the electro-optical panel to the first optical state of operation in order to induce the electro-optical glazing structure into the reflection mode of operation, and for switching the electro-optical panel to the second optical state of operation in order to induce the electro-optical glazing structure into the transmission mode of operation,

wherein the electro-optical panel comprises;

a sheet having a large plurality of pairs of layers parallel to a surface of the sheet, each pair of layers having a difference between the transparent polymer materials in each layer of the pair, the difference being in the index of refraction for electromagnetic radiation having the first linear polarization, wherein there is little difference in the index of refraction for electromagnetic radiation having the second linear polarization, the total thickness of each pair of layers in the large plurality of layers varying non linearly across the thickness of the sheet.

12. The electro-optical glazing structure of claim 11, wherein the electro-optical panel further reflects circularly polarized electromagnetic radiation.

13. The electro-optical glazing structure of claim 12, wherein the electro-optical panel further comprises a cholesteric liquid crystal (CLC) material.

14. The electro-optical glazing structure of claim 11, wherein the electro-optical panel selectively transmits and reflects electromagnetic radiation of a first bandwidth of the EM spectrum, further comprising a reflector of EM radiation which reflects radiation in a second bandwidth of the EM spectrum, the reflector of EM radiation which reflects radiation in a second bandwidth comprising a sheet having a large plurality of pairs of layers parallel to a surface of the sheet, each pair of layers having a difference in the index of refraction between the materials in each layer of the pair.

15. The electro-optical glazing structure of claim 14, wherein the reflector of EM radiation which reflects radiation in a second bandwidth has total thickness of each pair of layers in the large plurality of layers varying non linearly across the sheet.

16. The electro-optical glazing structure of claim 11, further comprising a controllable scattering layer.

17. The electro-optical glazing structure of claim 16, wherein the controllable scattering layer comprises a fluid medium containing a large plurality of anisotropically shaped objects for controllably scattering light, the orientation of anisotropically shaped objects controllable by a field.

18. The electro-optical glazing structure of claim 16, wherein the controllable scattering layer comprises a polymer medium containing a large plurality of inclusions, each inclusion containing liquid crystal material, the liquid crystal material controllable by a field.

19. The electro-optical glazing structure of claim 16, wherein the controllable scattering layer comprises a mixture of a polymer medium and a liquid crystal material, the liquid crystal material controllable by a field.

20. The electro-optical glazing structure of claim 11, wherein the electro-optical panel selectively transmits and reflects electromagnetic radiation of a first bandwidth of the EM spectrum, further comprising a reflector of EM radiation which reflects radiation in a second bandwidth of the EM spectrum, the reflector of EM radiation which reflects radiation in a second bandwidth comprising CLC layers of different handedness.

21. The electro-optical glazing structure of claim 20, the CLC layers have a non linear pitch distribution.

22. The electro-optical glazing structure of claim 11, further comprising a controllable absorbing layer.

23. The electro-optical glazing structure of claim 11, wherein the means for further controlling the electromagnetic radiation comprises an absorbing layer for controllably absorbing light.

24. The electro-optical glazing structure of claim 23, wherein absorbing layer is an electrochromic absorbing layer.