Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS20100118380 A1
Publication typeApplication
Application numberUS 12/688,843
Publication dateMay 13, 2010
Filing dateJan 15, 2010
Priority dateMay 18, 2007
Also published asCA2724846A1, CN102066993A, EP2291693A2, US7973998, US20090219603, US20120002264, WO2009143172A2, WO2009143172A3
Publication number12688843, 688843, US 2010/0118380 A1, US 2010/118380 A1, US 20100118380 A1, US 20100118380A1, US 2010118380 A1, US 2010118380A1, US-A1-20100118380, US-A1-2010118380, US2010/0118380A1, US2010/118380A1, US20100118380 A1, US20100118380A1, US2010118380 A1, US2010118380A1
InventorsJiuzhi Xue
Original AssigneeJiuzhi Xue
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Temperature activated optical films
US 20100118380 A1
Abstract
The present invention discloses a multilayer dielectric optical structure wherein one of the optical materials in the multilayer structure shows an optically isotropic state above and a birefringent state below a characteristic temperature Tc near the room temperature. The optical structure reflects a predetermined wavelength range of electromagnetic radiation above the Tc but allow the same to transmit through below the Tc. The predetermined wavelength can be the near infrared radiation from 700 nm to 2500 nm, and the optical structure rejects solar heat in warm summer days but admits the same to interior on a colder winter day.
Images(6)
Previous page
Next page
Claims(47)
1. A multilayer dielectric optical structure, for selectively reflecting a predetermined wavelength, comprising:
a transparent substrate;
a plurality of alternating first layers and second layers on the substrate, wherein the first layers comprise a first optical material having a first optical axis and a first refractive index along the first optical axis, and the second layers comprise a second optical material having a second optical axis and a second refractive index along the second optical axis below a characteristic transition temperature Tc and a third refractive index above the Tc, the first and second optical axis are substantially parallel and the first and second refractive indices are substantially equal, the third refractive index differ from the second refractive index and from the first refractive index; and
wherein the optical thickness of each of the first layer is equal to times the predetermined wavelength and the optical thickness of each of the second layer when the temperature is above the Tc is equal to times the predetermined wavelength. A human stem cell that is pluripotent, somatic, non-embryonic, and having the property of long-term self renewal.
2-23. (canceled)
24. A reflective polarizer film for regulating reflection of incident radiant energy comprising
a first optical layer;
a second optical layer; and
a temperature sensitive optical material positioned between the first optical layer and the second optical layer.
25. The film of claim 24, wherein
at a first temperature a first percentage of the incident radiant energy is reflected from the film and a second percentage of the incident radiant energy is transmitted through the film; and
at a second temperature a third percentage of the incident radiant energy is reflected from the film and a fourth percentage of the incident radiant energy is transmitted through the film.
26. The film of claim 24, wherein
the temperature sensitive optical material adjusts polarization of incident light when below a threshold temperature;
above the threshold temperature up to 100% of incident light is reflected by the film, and below the threshold temperature up to 50% of incident light is reflected by the film.
27. The film of claim 24, wherein
the first optical layer reflects up to 50% of the incident radiant energy and transmits a majority of non-reflected radiant energy; and
the second optical layer reflects up to 100% of radiant energy transmitted by the first optical layer when the temperature sensitive optical material is above the threshold temperature and transmits up to 100% of radiant energy transmitted by the first optical layer when the temperature sensitive optical material is below the threshold temperature.
28. The film of claim 24, wherein the second optical layer is frequency selective with respect to polarization of the radiant energy.
29. The film of claim 24, wherein the film is in the form of a thin and flexible film.
30. The film of claim 24 further comprising a transparent substrate that supports the first optical layer, the second optical layer, and the temperature sensitive optical material.
31. The film of claim 30, wherein the transparent substrate is a solid substrate.
32. The film of claim 24, wherein the film is incorporated into a construction material for regulating the flow of incident light into, and thus regulating the internal temperature of, a building, a vehicle, or other structure.
33. The film of claim 32, wherein the construction material is an insulating glass unit.
34. The film of claim 24 further comprising a transparent substrate.
35. The film of claim 24, wherein a range of wavelengths of radiant energy regulated by the film comprises one or more of visual, infrared, or near-infrared wavelengths.
36. The film of claim 24, wherein either or both of the first optical layer and the second optical layer is spectrally selective.
37. The film of claim 24, wherein the first optical layer and the second optical layer each have different polarizing efficiencies, polarizing responses, or both at different frequencies.
38. The film of claim 24, wherein each of the first optical layer and the second optical layer has a different polarizing nature at different frequencies.
39. The film of claim 24, wherein either or both of the first optical layer and the second optical layer comprises a combination of multiple optical layers.
40. The film of claim 24, wherein the temperature sensitive optical material comprises a liquid crystal.
41. The film of claim 40, wherein the liquid crystal further comprises an additive in a mixture with the liquid crystal to affect optical properties of the liquid crystal, a speed of transition between physical states of the liquid crystal, or both.
42. The film of claim 41, wherein the additive comprises a second type of liquid crystal mixed with the liquid crystal.
43. The film of claim 40, where the additive is selected to improve the stability of a functional response of the film to environmental conditions.
44. The film of claim 24, where the temperature sensitive optical material is designed or selected based upon frequency dependent properties of the temperature sensitive optical material with respect to a rotation of polarized light to affect one or more of aesthetic, color, light or energy transmission, absorption, and reflection properties of the film.
45. A reflective polarizer film for regulating the reflection of light comprising a first optical layer that reflects up to 50% of incident light and passes up to 50% of the incident light;
a second optical layer, and
a temperature sensitive optical material positioned between the first optical layer and the second optical layer that adjusts polarization of incident light below a threshold temperature, wherein
above the threshold temperature up to 100% of incident light is reflected by the film, and below the threshold temperature up to 50% of incident light is reflected by the film.
46. The film of claim 45 further comprising a transparent substrate that supports the first optical layer, the second optical layer, and the temperature sensitive optical material.
47. The film of claim 46, wherein the transparent substrate is a solid substrate.
48. The film of claim 45, wherein the film is in the form of a thin and flexible film.
49. A reflective polarizer film for regulating the reflection of incident radiant energy comprising
a first layer of birefringent optical material; and
a second layer of temperature sensitive optical material, wherein
above a threshold temperature down to 0% of incident radiant energy is transmitted by the film, and
below the threshold temperature up to 100% of the incident radiant energy is transmitted by the film;
at a first temperature a first percentage of the incident radiant energy is reflected from the film and a second percentage of the incident radiant energy is transmitted through the film; and
at a second temperature a third percentage of the incident radiant energy is reflected from the film and a fourth percentage of the incident radiant energy is transmitted through the film.
50. A method for regulating reflection and transmission of radiant energy comprising orienting a first optical layer of birefringent optical material perpendicular to a second layer of temperature sensitive optical material;
reflecting up to 100% of incident radiant energy with the first and second layers when above a threshold temperature; and
wherein when below a threshold temperature the first and second layers cease to polarize below the threshold temperature,
transmitting up to 100% of the incident radiant energy.
51. A method for regulating an internal temperature of a building, a vehicle, or other structure comprising
placing a temperature activated optical film on an exterior of a structure; and
inverting a temperature response of the film whereby the film is primarily reflective of incident radiant energy at high temperatures and comparatively more transparent to, absorbent of, or both, incident radiant energy at low temperatures.
52. The method of claim 51 further comprising positioning the film on the structure to receive maximum incident radiant energy at cold temperatures or in the winter season and to receive minimum incident radiant energy at high temperatures or in the summer season.
53. A switchable shutter device for regulating reflection of incident radiant energy comprising
a first reflective polarizer;
a second polarizer; and
a thermotropic depolarizer positioned between the first reflective polarizer and the second polarizer.
54. The device of claim 53, wherein
at a first temperature a first percentage of the incident radiant energy is reflected from the device and a second percentage of the incident radiant energy is transmitted through the device; and
at a second temperature a third percentage of the incident radiant energy is reflected from the device and a fourth percentage of the incident radiant energy is transmitted through the device.
55. The device of claim 53, wherein the device is incorporated into a construction material for regulating the flow of incident light into, and thus regulating the internal temperature of, a building, a vehicle, or other structure.
56. The device of claim 54, wherein the construction material is an insulating glass unit.
57. The device of claim 53 further comprising one or more of the following components: an external reflector, a color filter, a UV or harmful radiation filter, a transparent substrate, a filled or hollow space to provide thermal insulation, an antireflective coating, conductive or insulating adhesives or layers to improve the temperature sensing ability of the device, phase change materials, and low emissivity coatings or devices.
58. The device of claim 53, wherein a range of wavelengths of radiant energy regulated by the device comprises one or more of visual, infrared, ultraviolet, radio, radar, or microwave wavelengths.
59. The device of claim 53, wherein the thermotropic depolarizer comprises a liquid crystal.
60. The device of claim 59, wherein the liquid crystal further comprises an additive in a mixture with the liquid crystal to affect optical properties of the liquid crystal, a speed of transition between physical states of the liquid crystal, or both.
61. A switchable optical shutter device for regulating the reflection of light comprising a first reflective polarizer that reflects up to 50% of incident light and passes up to 50% of the incident light;
a second reflective polarizer, and
a thermotropic depolarizer positioned between the first reflective polarizer and the second polarizer that adjusts polarization of incident light below a threshold temperature, wherein
above the threshold temperature up to 100% of incident light is reflected by the device, and
below the threshold temperature up to 50% of incident light is reflected by the device.
62. An insulating glass unit comprising
a first plate of glass;
a second plate of glass;
a first reflective polarizer positioned between the first plate of glass and the second plate of glass that reflects up to 50% of incident radiant energy and transmits a majority of non-reflected radiant energy;
a second reflective polarizer positioned between the first plate of glass and the second plate of glass; and
a thermotropic depolarizer positioned between the first reflective polarizer and the second polarizer that adjusts polarization of incident light below a threshold temperature, wherein
above the threshold temperature up to 100% of incident light is reflected by the device;
below the threshold temperature up to 50% of incident light is reflected by the device; and
the second polarizer reflects up to 100% of radiant energy transmitted by the first reflective polarizer when the thermotropic depolarizer is above the threshold temperature and transmits up to 100% of radiant energy transmitted by the first reflective polarizer when the thermotropic polarizer is below the threshold temperature.
63. A switchable shutter device for regulating the reflection of incident radiant energy comprising
a first thermotropic polarizer; and
a second thermotropic polarizer, wherein
above a threshold temperature down to 0% of incident radiant energy is transmitted by the device, and
below the threshold temperature up to 100% of the incident radiant energy is transmitted by the device;
at a first temperature a first percentage of the incident radiant energy is reflected from the device and a second percentage of the incident radiant energy is transmitted through the device; and
at a second temperature a third percentage of the incident radiant energy is reflected from the device and a fourth percentage of the incident radiant energy is transmitted through the device.
64. A method for regulating reflection and transmission of radiant energy comprising
orienting a first reflective polarizer crosswise with a second polarizer;
reflecting up to 50% and absorbing up to 50% of incident radiant energy with the first reflective polarizer and the second polarizer when above a threshold temperature; and
when below the threshold temperature,
depolarizing a portion of the incident radiant energy transmitted between the first reflective polarizer and the second polarizer;
transmitting up to 50% of the radiant energy through the first reflective polarizer and the second polarizer; and
reflecting up to 50% of the incident radiant energy.
65. A method for regulating reflection and transmission of radiant energy comprising
orienting a first thermotropic polarizer crosswise with a second thermotropic polarizer;
reflecting up to 100% of incident radiant energy with the first and second thermotropic polarizers when above a threshold temperature; and
wherein when below a threshold temperature the first and second thermotropic polarizers cease to polarize below the threshold temperature,
transmitting up to 100% of the incident radiant energy.
66. A method for regulating reflection and transmission of radiant energy comprising
orienting a reflective polarizer crosswise with a polarity-rotating polarizer;
interposing a thermotropic depolarizer between the reflective polarizer and the polarity-rotating polarizer
reflecting up to 100% of incident radiant energy with the reflective polarizer and the polarity-rotating polarizer when the thermotropic depolarizer is above a threshold temperature; and
when below a threshold temperature,
transmitting up to 100% of the incident radiant energy through the reflective polarizer, thermotropic depolarizer, and the polarity-rotating polarizer.
67. A method for displaying a reflective image comprising
arranging a thermoreflective material or device on a surface in a shape of a desired image or removing the thermoreflective material in an area to form an image area; and
reflecting incident light from the thermoreflective material above or below a particular threshold temperature or range of temperatures, wherein the reflective image becomes visible.
68. A method for regulating an internal temperature of a buildings, a vehicle, or other structure comprising
placing a thermoreflective material on an exterior of a structure; and
inverting a temperature response of the thermoreflective material whereby the thermoreflective material is primarily reflective of incident radiant energy at high temperatures and comparatively more transparent to, absorbent of, or both, incident radiant energy at low temperatures.
Description
    CROSS-REFERENCE
  • [0001]
    This application is a continuation of U.S. Non-Provisional application Ser. No. 12/152,969, filed May 19, 2008, which claims the benefit of U.S. Provisional Application No. 60/930,894, filed May 18, 2007, the contents of both of which are incorporated herein by reference in their entirety.
  • BACKGROUND OF THE INVENTION
  • [0002]
    The present invention generally relates to a multilayer dielectric optical structure that selectively reflects a predetermined wavelength of electromagnetic radiation. More particularly, this invention relates to the optical structure whose change of optical property is activated by temperature.
  • [0003]
    Glass windows are widely used in residential and commercial buildings for the purpose of natural light collection as well as for aesthetic reasons. However, glass windows, as they are generally a thin and transparent barrier separating the interior for example an office space to the outside environment, can readily exchange heat with the outside environment via two paths: direct heat exchange due to thermal motions of air, and passage of electromagnetic radiation. The reduction of direct heat exchange due to thermal motion between an interior and external environment are generally always preferred. For electromagnetic radiation, there are two major contributions as far as heat exchange is concerned: the long wavelength radiation due to blackbody radiation of objects near room temperature, and the solar electromagnetic radiation. Similar to heat exchange due to thermal motion, the transfer of blackbody radiation due to objects near room temperature are generally not preferred as they present a heat loss due to interior in colder days (to colder environment) and heating of interior on hotter days from hotter external environment. However, heating due to solar radiation is a different matter. Although visible light in general are preferred to transmit through the windows to interior, the near infrared spectrum of solar radiation or the heat component of the solar spectrum are desirable only in colder days, and on a hot summer day, rejection of the solar heat is very much desirable.
  • [0004]
    To reduce the heat exchange due to thermal motion, double pane glass windows with an air gap or inert gas filled gaps or triple pane glass windows are often used. However, these windows do not reduce or increase solar heat gain, as they absorb or reflect only a very small and fixed amount of electromagnetic radiation in the visible and infrared range that are essentially purely due to Fresnel reflections.
  • [0005]
    Current techniques employed in reducing the passage of electromagnetic radiation via glass windows include the technique of coating a very thin layer or layers of material, for example, silver and silver nitride layers, that behaves nearly as a metal mirror for wavelengths of about 10 μm? electromagnetic radiation. Such coated windows are commonly known as low e or low emissivity windows, and reflect the long wavelength electromagnetic radiations back to the environment or interior of a building. Such coatings increase the heat insulation properties of windows at all temperatures.
  • [0006]
    Selective reflection and absorption of near infrared radiation is a mature technology with great commercial success. An example is Solarban 70XL coatings produced by PPG Industries, Inc. Such coatings block most of near infrared and partially visible light constantly, both in colder and warmer days.
  • [0007]
    However, it is desirable to have a window or a film that have high transmission of visible light; high transmission of infrared radiation when temperature is low; transition to high reflection of infrared radiation when temperature reaches certain level; the transition temperature is at room temperature range; the switching is automatic depending on the temperature; the window or film can be inexpensively mass produced and non-toxic.
  • PRIOR ARTS
  • [0008]
    U.S. Pat. No. 3,279,327 to Ploke disclosed a multilayer optical filter for selectively reflecting infrared radiation while allowing visible light to transmit by means of interference.
  • [0009]
    U.S. Pat. No. 4,229,066 to Rancourt et al, disclosed a multilayer stack which is reflecting in the infrared and transmitting at shorter wavelengths. The stack is formed of a plurality of layers of high and low index materials with alternate layers being formed of materials having a high index of refraction and the other layers being formed of materials having a low index of refraction.
  • [0010]
    U.S. Pat. No. 3,711,176 to Alfrey et al, disclosed a multilayer films of polymer materials with sufficient mismatch in refractive indices, these multilayer films cause constructive interferences of light. This results in the film transmitting certain wavelengths of light through the film while reflecting other wavelengths.
  • [0011]
    U.S. Pat. No. 3,790,250 to Mitchell disclosed a system, where the conductivity of a light absorbing semiconductor varies with the temperature, and inversely, the light absorption or attenuation level is controlled by the temperature. The disclosed system show a light absorption of about 80% at 80 C. and the absorption is reduced to about 15% at room temperature. This system is not useful for present application because its temperature dependence changes slowly over a wide range of temperature.
  • [0012]
    U.S. Pat. No. 4,307,942 to Chahroudi disclosed a solar control system where various structure consisting of porous layers absorb the solvents or repel the solvents depending on the temperature and the structures change their optical properties from transparent to solar radiation at low temperatures to a metallic surface or a dielectric mirror to reflect solar radiation of predetermined wavelengths. A significant difficulty in implementing such a device, aside from any performance issues, is that there must be a significant reservoir to hold such solvents.
  • [0013]
    U.S. Pat. No. 4,401,690 to Greenberg disclosed a method for making thin films of vanadium oxide possessing such a transition with depressed transition temperature of 25 C. to 55 C., approaching but not quite the transition temperature needed in order that the material to be useful. In addition, vanadium oxides in temperatures below or above the transition temperature absorb a significant portion of visible light, which makes the technology less attractive for window applications.
  • [0014]
    U.S. Pat. No. 6,049,419 to Wheatley disclosed a dielectric multilayer structure consisting of birefringent polymer layers that will reflect at least one polarization of predetermined wavelengths. However, the optical properties including its reflectance will not change with the temperature, and the resulting optical structure will reject solar energy on a warmer summer day, which is desirable, as well as on a cold winter day if so designed, which is not desirable.
  • [0015]
    US invention disclosure No. H001182 by Spry disclosed an optical filter structure using a material that has a ferroelectric phase to a non ferroelectric phase transition upon changing in temperature and another optically clear material that does not have the phase transition. The resulting optical filter structure can selectively block radiation of a predetermined wavelength, as the refractive index of the phase changing layer changes as temperature change. However, the transition temperature of ferroelectric materials occur at about 120 C., the induced index of refraction change is about 0.03, and as both layers are optically isotropic in the reflection mode at high temperature, the device will only reflect a nearly normal incident single wavelength light at very high temperatures, and it will require a large number of layers, greater than 5000 to achieve significant reflection across a broadband of near infrared radiations, therefore that will not be applicable for adjusting solar energy control at room temperature range.
  • [0016]
    Accordingly, the unfulfilled needs still exists in this art for a window or an optical film that have high transmission of visible light; high transmission of infrared radiation when temperature is low; transition to high reflection of infrared radiation when temperature reaches certain level; the transition temperature is at room temperature range; the switching is automatic depending on the temperature; the window or film can be inexpensively mass produced; the material used for such windows or films is non-toxic.
  • OBJECTIVES AND SUMMARY OF THE INVENTION
  • [0017]
    The present invention meets the needs by providing a multilayer dielectric optical structure that is made of polymer and liquid crystal materials. The optical structure is substantially transparent of visible and infrared light when temperature is below a transition temperature in the range between 15-35 degree Celsius, while have high reflectance of infrared light when temperature is above the transition temperature. The number of layers required to reflect a wide band of infrared light is between 100 to 1000 layers. A film or a window in accordance with the present invention is particularly useful for passive solar energy control since it has high visible light transmittance, significantly lower infrared transmittance above transition temperature, has a sufficiently low transition temperature range to be useful in a wide variety of climatic conditions, and the only activation required is the change in ambient temperature that the films or the windows can directly sense.
  • [0018]
    The following embodiments and objectives of therefore are described and illustrated in conjunction with systems, tools, and methods which are meant to be exemplary and illustrative, and not limiting in scope. In various embodiments, one or more of the above-described market desires have been met by the present invention, while other embodiments are directed to other improvements.
  • [0019]
    A primary objective of the present invention is to provide an optical structure that transmit visible lights and infrared radiation at a temperature below a characteristic transition temperature, reflect the infrared radiation when temperature is above the transition temperature, which the transition temperature is in the room temperature range.
  • [0020]
    Another objective of the present invention is to provide a flexible optical film structure where the film transmits the visible light at all temperatures but reflects the near infrared or heat generating spectrum of solar electromagnetic radiation above a desired temperature setting but allows the transmission of such solar heat at lower temperatures.
  • [0021]
    Another objective of the present invention is to provide a temperature dependent reflective polarizer film where above a predetermined temperature setting the film reflects one polarization of electromagnetic radiation of certain wavelength range in the visible and near infrared spectrum while transmitting the electromagnetic radiation with polarization substantially perpendicular to the reflected polarization in the spectral range, and transmitting electromagnetic radiation of all polarizations outside the spectral range. Below the predetermined temperature setting, the film is substantially transparent to the electromagnetic radiation of all wavelengths and polarization states in the visible and near infrared range.
  • [0022]
    Another principle objective of the present invention is to provide such an optical film that is plastic film based and that it is readily mass producible and can be readily retrofit into existing windows as well.
  • [0023]
    A further objective of the present invention is to provide an optical system that reflects a broadband of infrared radiation when temperature is above the transition temperature while it is transparent to visible light, transparent to both visible and infrared radiation when below the transition temperature.
  • [0024]
    Other objectives and advantages will be apparent from the following description of the invention.
  • INCORPORATION BY REFERENCE
  • [0025]
    All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0026]
    The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
  • [0027]
    Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein be considered illustrative rather than limiting.
  • [0028]
    FIG. 1 is a schematic, illustrative view of a sectional a multilayered structure of the invention.
  • [0029]
    FIG. 2 is a schematic, illustrative view of a stretched polymer and liquid crystal align along stretch direction.
  • [0030]
    FIG. 3 is schematic, illustrative view of certain polarization is reflected when above transition temperature.
  • [0031]
    FIG. 4 is schematic, illustrative view of two identical reflecting film stacked together with perpendicular optical axes, forming a pair complete reflect certain wavelength at above transition temperature.
  • [0032]
    FIG. 5 is a schematic, illustrative view of a polymer mesh network for containing liquid crystal and mechanical structure stable.
  • DETAILED DESCRIPTION OF THE INVENTION
  • [0033]
    As used herein, “a” or “an” means one or more.
  • [0034]
    As used herein, “Polarization” means the orientation of the electric field oscillations in the plane perpendicular to the electromagnetic wave's direction of travel.
  • [0035]
    As used herein, “μm” means micro meter, 1/1000000 of a meter in length.
  • [0036]
    As used herein, “nm” means nano meter, 1/1000000000 of a meter in length.
  • [0037]
    As used herein, “birefringent” and “birefringence” means an optical material that shows different effective index of refraction along different directions.
  • [0038]
    As used herein, “Optical axis” and “optical axes” means the principal direction or directions of the index ellipsoid of a birefringent material. For biaxial birefringent materials, there are three mutually perpendicular optical axis. For uniaxial materials, typically only one axis, the direction along the extraordinary index of refraction is used.
  • [0039]
    As used herein, “refractive index along an optical axis” means a numerical number that measures how much the speed of light is reduced inside the medium when the electromagnetic radiation is polarized along the optical axis. For birefringent optical materials, there are three refractive indices along the three principal optical axes respectively. If all three refractive indices are same, is the material is isotropic. If two refractive indices are same, the material is uniaxial.
  • [0040]
    As used herein, “optical thickness” means the layers physical thickness times its refractive index. For birefringent material, optical thickness is direction dependent because of direction dependency of refractive indices.
  • [0041]
    As used herein, “transition temperature” or “Tc” means a temperature at which liquid crystal material undergoes a phase transition, from the isotropic state when above Tc, to an ordered or liquid crystalline state when below Tc.
  • [0042]
    Embodiments disclosed herein relate to a multi-layer dielectric optical structure, more specifically a polymer/liquid crystal smart optical plastic film that has a transition temperature Tc. Above Tc it reflects a specific spectral range of electromagnetic radiation in the near infrared spectrum but transmits the electromagnetic radiation outside this specific spectral range. Below Tc, the optical structure is substantially transparent to visible and infrared radiation. Specifically, in one preferred embodiment disclosed herein, the optical structure is designed to have optical plastic films reflecting near infrared radiation of wavelengths from 700 nm to 2500 nm at temperatures of 20 C. and above while transmitting such radiation at temperatures below the temperature of choice, but are substantially transparent to visible light of wavelengths from 400 nm to 700 nm at all time. This structure can be used for an optically clear film that utilizes solar heat when needed on a colder day or in a cold environment but rejects infrared radiation on hotter days. Such an optical film will find wide range of applications in architectural, vehicular, and other industries.
  • [0043]
    As shown in FIG. 1 a basic structure of a structured film that reflects a spectral range of electromagnetic radiation, for example at around wavelength of 1.0 μm, while transmitting other wavelengths of electromagnetic radiation. The film stack is composed of alternating layers of two optical materials, first optical layer 101 and second optical layer 102 on a plastic or solid substrate 100. At least one of the layers, 101 or 102, or both, is birefringent. In one preferred embodiments, alternating layers 101 are comprised of uniaxial birefringent optical plastic films with optical axis along the layer normal of the films, and the alternating layers 102 are comprised of discotic liquid crystals with director along the layer normal when the material is in discotic phase. The discotic liquid crystal have an isotropic to discotic phase transition temperature Tc at around room temperature. The films 102 comprising discotic liquid crystals maybe polymerized for mechanical stability. When below the Tc, the layers 102 are in discotic liquid crystal phases, and the indices of refraction of the layers 101 and 102 are substantially matched in all three principal directions, and the layer is transparent to electromagnetic radiation 1000 of all wavelengths and all polarizations of interest. Above the Tc, the films 102 are in isotropic phase with a homogeneous index of refraction that is preferably designed to substantially match that of layers 101 along the optical axis. The refractive indices of the layers in the layer plane directions are mismatched. The effective optical thicknesses of both layers are designed to be quarter wavelength thick of the electromagnetic radiation 1000 of wavelengths around λ0, and reflections from interfaces are constructive. The reflection of the stack therefore peaks around the wavelength λ0 with the reflectance and the bandwidth dependent on the ratio of the index of refraction and the number of layers, the ratio of the index of two materials is defined as higher refractive index nH divided by the lower one nL, there is no reflection if the index ratio is 1, for birefringent optical materials, the ratio is also direction dependent. A larger index ratio requires less number of layers to achieve high reflectance and reflects a broader band of light, and a crude estimate show that to achieve close to 100% reflection at the peak wavelength, the number of required layers has to be greater than 1/(nH−nL), where nH and nL the indices of refraction of the high and low index optical films, respectively. Outside the peak wavelength band, the reflectance reduces, depending on the number of layers, and in oscillatory fashion.
  • [0044]
    One preferred embodiment as show in FIG. 1, the substrate is a clear polyester film available from a number of companies, including DuPont Teijin Films. The film thickness is in the range of 50 μm to 500 μm, preferably from 125 μm to 200 μm. The substrate can also be other clear plastic films, such as polyethylene films from same suppliers as polyester films, and with similar thickness.
  • [0045]
    On top of the substrate, we have liquid crystal layer 102. A mixture of liquid crystal and monomer additives are deposited onto the substrate. One example of the liquid crystal used for illustrative purposes is 6CB (4-cyano-4-hexylbiphenyl) available from Merck KGaA and with monomer additives bisacryloyl biphenyl and a small amount of benzoin-methyl-ether as initiators, the concentration of monomer additives is up to 20% wt, preferably 0.3-5% wt. After depositing layer to thickness of 271 nm, monomers were polymerized by exposed to a UV light, commonly known as photopolymerization method, forming a polymer mesh in the layer for the purpose of dividing liquid crystal material into small sections with less mobility and add to mechanical stability of the layer to maintain uniform thickness of the layer.
  • [0046]
    A polymer layer 101 is deployed on top of liquid crystal layer for sealing the layer and as the next, alternating polymer layer. The material for layer 101 is semi-crystalline polymer, such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). Biaxially stretched thin PET films as thin as 0.5 μm are readily available from suppliers such Goodfellow Corporation, Toray Industry, Inc. These films can be further stretched at temperatures of about 140 C. to at least get films as thin as about 0.25 μm. For a uniaxially stretched PET film, the indices of refraction depend on the stretching ratio. If the stretching ratio is 5 times, that is, the film length is 5 times that of the pre-stretching length, the three refractive indices are 1.70, 1.55, 1.50 along the stretching, in the film plane but perpendicular to the stretching direction, and along the film normal direction respectively. The optical thickness along the stretching direction of such a 0.25 μm thick layer is 0.425 μm and will reflect infrared radiations peaked at 1.7 μm in wavelength when paired with another optical material whose optical thickness is wavelength at the same wavelength. Uniaxially and uniformly stretched PET films as thin as about 0.05 μm in thickness can be prepared which give optical thicknesses along the stretching or ordering direction of 0.085 μm. Such uniformly stretched films, when stacked with alternating liquid crystal layers in isotropic phase with lower refractive index, will allow for constructive reflections of radiations with center wavelength peaked as short as at 340 nm, therefore our preferred interest range 700 nm to 2500 nm is easily achievable.
  • [0047]
    In another preferred embodiment as shown in FIG. 2, the multilayer stack is comprised of birefringent polymer layers 201, 203, 205, n, . . . , n+2 such as a stretched polyethylene terephthalate and liquid crystal layers 202, 204, . . . n+1, n+3 such as liquid crystal 6CB on a base substrate 200. The liquid crystal molecules are rod-shaped. In the nematic liquid crystal or higher ordered liquid crystal or crystal phases, the material is uni-axial or biaxial in optical properties, and is isotropic when in isotropic phase. When stretched along the y axis as shown in FIG. 2, the polymer layer is generally uniaxial optically with its optical axis along the stretching direction of y axis and with ordinary index of refraction no along the x and z direction and extraordinary index of refraction ne along the stretching y direction. Furthermore, the stretched polymers act as alignment layers for liquid crystals that enable the polymer films to align liquid crystal directors along the stretching direction.
  • [0048]
    According to the present invention, at low temperatures where the liquid crystal layers are in nematic liquid crystal or higher ordered phases, the indices of refraction and the thicknesses of the polymer layers and the liquid crystal layers do not satisfy the Bragg interference conditions, preferably, the indices of refraction of the polymer and liquid crystal materials are substantially matched in at least x and y directions. The film stack is therefore transparent to incident light 1000 in all wavelengths and all polarizations in the visible and near infrared spectrum that is of interest in this invention. 6CB, the nematic to isotropic phase transition temperature is 29 C. At about 13 C. nx=nz=no=1.53, and ny=ne=1.71, substantially matching the indices of the polymer layer.
  • [0049]
    At temperatures above the liquid crystal to isotropic phase transition temperature, the liquid crystal layers 302, 304, . . . , 3+1, n+3 becomes isotropic and the indices of refraction of liquid crystal becomes isotropic with nx=ny=nz=n1c, which in general is close to be the same as the ordinary index of the liquid crystals in their liquid crystal phases, as shown in FIG. 3. The liquid crystal layers thus are substantially index matched with the polymer layers 301, 303, . . . , n, n+2 in the x and z direction but are mismatched in the y or, in the case of stretched polymer films, the polymer stretching direction. For s-polarized incoming light 1002 (polarization along x-axis), the indices for the polymer layers and liquid crystal layers are substantially matched and thus the film stack is transparent to the incoming light. For p-polarized incoming light, the effective indices of polarization in the polymer layers and in the isotropic liquid crystal layers are different.
  • [0050]
    In one example, an alternating PET film and liquid crystal 6CB has shown the following parameters and properties:
  • [0051]
    PET film thickness: 0.25 μm, uni-directionally stretched.
  • [0052]
    6CB layer thickness: 0.271 μm
  • [0053]
    Number of layer pairs N=22
  • [0054]
    Transition temperature: 29 C.
  • [0055]
    Transmisivity of near infrared spectrum: (1700 nm) at T>29 C., 6.5%
  • [0056]
    Transmisivity of the near infrared radiation at T<20 C. and radiation at other wavelengths for all temperatures: 90%
  • [0057]
    According to the embodiments disclosed herein, at temperatures above the liquid crystal to isotropic phase transition temperature, the thicknesses of the layers 301, 302, 303 . . . are designed such that a specific wavelength range of p-polarized electromagnetic radiation 1001 is reflected by the layer. In one specific embodiment, the film stack shown in FIG. 3 is designed to only substantially reflect p-polarized near infrared electromagnetic radiation of wavelengths from 700 nm to 2500 nm when the liquid crystal films 302, 304, . . . are in isotropic phase but to transmit the visible light 1003 and s-polarized near infrared electromagnetic radiation 1002. In another preferred embodiment, the film is designed to only substantially reflect a narrower spectrum range, for example, from 1000 nm to 1500 nm of p-polarized electromagnetic radiation when the liquid crystal layers are at higher temperature and in isotropic phase.
  • [0058]
    In the preferred embodiment, broadband spectrum reflection at high temperature by the films disclosed in FIG. 1 and FIG. 2 and FIG. 3 are achieved by varying the thickness of the films such that the center wavelength of constructive reflection gradually varies across the film. Thus the thickness of layer 301 is different from the thickness of layer 303 and further the thickness of both layers may be different from that of the layer n in the film stack. In another preferred embodiment, films reflecting specific but different ranges of electromagnetic radiation are stacked together to broaden the overall reflecting spectral range of the film stack.
  • [0059]
    In one preferred embodiment, a multilayer optical film is formed by a stack of dielectric layer pairs with slightly variant optical thickness. A dielectric pair is formed by one polymer layer and a matching liquid crystal layer. The formed multilayer polymer and liquid crystal structure is then subject to a unidirectional mechanical stretching. Above Tc, the stretched multilayer structure satisfies the condition that both layers in the pair have same optical thickness that equals to of a representative nominal wavelength. The relationship between each adjacent layer pairs is in accordance to the formula: dN+1=r dN, where dN is the optical thickness of pair N, r is a numerical factor in the range of 0.85 to 0.999, where d1= λ0, where λ0 is the nominal wavelength substantially the same as the upper wavelength limit of the broadband of interest. Preferably for a broadband near infrared reflecting device, λ%0 is in the range of 1500 nm to 2500 nm. The multilayer structure so formed reflects a broadband of infrared radiation. Number of layers required in our example is not very large due to the large difference in refractive indices at liquid crystal transition temperature, as shown in the following example:
  • [0060]
    An alternating PET film and 6CB has shown the following parameters and properties:
  • [0061]
    PET film thickness: 0.1 μm-0.354 μm, uni-directionally stretched.
  • [0062]
    6CB layer thickness: 0.128 μm-0.416 μm
  • [0063]
    Transition temperature: 29 C.
  • [0064]
    Number of layer pairs N=115
  • [0065]
    λ0=2400 nm
  • [0066]
    Transmisivity of visible lights (wavelength 400 nm to 700 nm) at T>29 C., 80%
  • [0067]
    Trasmisivity of near infrared spectrum: (700 nm-2500 nm) at T>29 C., 55%
  • [0068]
    Trasmisivity of visible lights at T<20 C., 93%
  • [0069]
    Trasmmisivity of near infrared radiation at T<20 C., 93%
  • [0070]
    In another preferred embodiment disclosed in FIG. 4, two optical films 400 and 401 of type disclosed in FIG. 2 and FIG. 3 are stacked together with there optical axes 411 and 412 substantially perpendicular to each other to form a composite film that reflect all polarizations of light in the desired spectral range of electromagnetic radiation at high temperatures while transmitting the same at low temperatures. The composite film transmits electromagnetic radiation outside the spectral range at all temperatures. In one preferred embodiment, the visible incoming light 420 is transmitted by the composite film at all temperatures. However, for the near infrared incoming light 425, the composite film reflects it to 426 at high temperatures when the liquid crystal layers are in isotropic phase and transmits it to 427 at low temperatures when the liquid crystal layers are in nematic liquid crystal or higher ordered phases.
  • [0071]
    One specific property related to liquid crystal is its ability to flow. In a preferred embodiment, polymerizable monomers are doped in liquid crystal layers 502. The doped monomers may be photo-polymerized to form a network 510 that forms a containing mesh for liquid crystal molecules 511, as shown in FIG. 5. Alternatively monomers may be polymerized by heating the liquid crystal monomer mixture to form the network 510. Such network 510 will form a three dimensional mesh that result in a mechanically stable liquid crystal film. In another preferred embodiment, the liquid crystal layers are comprised of polymer liquid crystals with polymer backbones to provide rigidity and mechanical stability to the liquid crystal layer. In yet another preferred embodiment, the polymerizable monomers form thin closed walls and the liquid crystals are contained within these walls wherein the mobility of the liquid crystals is limited.
  • [0072]
    Although liquid crystal molecules are disclosed in this invention as the temperature sensitive optical material, various types of other optical materials with refractive index sensitive to temperature can be incorporated into present invention, so long as the refractive index of the optical materials experience a significant, greater than 0.05 change when the temperature of the film is changed over a narrow range, particularly when the temperature change occurs near the room temperature.
  • [0073]
    The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such variations, modifications, permutations, additions, and sub-combinations as are within their true spirit and scope.
  • [0074]
    While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.
Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3279317 *Jun 25, 1962Oct 18, 1966Zeiss Ikon AgOptical filter device with two series of interference layers for transmitting visible light and reflecting heat radiation
US3711176 *Jan 14, 1971Jan 16, 1973Dow Chemical CoHighly reflective thermoplastic bodies for infrared, visible or ultraviolet light
US3790250 *Aug 25, 1971Feb 5, 1974Us NavyThermally-activated optical absorber
US3990784 *Jun 5, 1974Nov 9, 1976Optical Coating Laboratory, Inc.Coated architectural glass system and method
US4229066 *Sep 20, 1978Oct 21, 1980Optical Coating Laboratory, Inc.Visible transmitting and infrared reflecting filter
US4268126 *Dec 20, 1978May 19, 1981Allied Chemical CorporationThermal-pane window with liquid crystal shade
US4307942 *Mar 10, 1980Dec 29, 1981The Southwall CorporationSolar control system
US4401690 *Feb 1, 1982Aug 30, 1983Ppg Industries, Inc.Thermochromic vanadium oxide with depressed switching temperature
US4456335 *Dec 5, 1980Jun 26, 1984Allied CorporationThermal-pane window with liquid crystal shade
US4475031 *Apr 23, 1981Oct 2, 1984Grumman Aerospace CorporationSolar-powered sun sensitive window
US4497390 *May 23, 1983Feb 5, 1985Wilson Frederick DSelf-adjusting ladder
US4512638 *Aug 31, 1982Apr 23, 1985Westinghouse Electric Corp.Wire grid polarizer
US4641922 *Aug 26, 1983Feb 10, 1987C-D Marketing, Ltd.Liquid crystal panel shade
US4755673 *May 6, 1986Jul 5, 1988Hughes Aircraft CompanySelective thermal radiators
US4789500 *Mar 28, 1986Dec 6, 1988Futaba Denshi Kogyo Kabushiki KaishaOptical control element
US4848875 *Jun 25, 1987Jul 18, 1989Allied-Signal Inc.Dual-pane thermal window with liquid crystal shade
US4871220 *Jun 15, 1988Oct 3, 1989Litton Systems, Inc.Short wavelength pass filter having a metal mesh on a semiconducting substrate
US4877675 *Sep 29, 1988Oct 31, 1989Waqidi FalicoffLight transmitting or reflective sheet responsive to temperature variations
US4893902 *May 12, 1989Jan 16, 1990Allied-Signal Inc.Dual-pane thermal window with liquid crystal shade
US4899503 *Aug 25, 1989Feb 13, 1990Allied-Signal Inc.Dual-pane thermal window with liquid crystal shade
US4964251 *Oct 23, 1989Oct 23, 1990Allied-Signal Inc.Dual-pane thermal window with liquid crystal shade
US5009044 *Apr 26, 1990Apr 23, 1991Allied-Signal Inc.Dual-pane thermal window with liquid crystal shade
US5025602 *Oct 15, 1990Jun 25, 1991Allied-Signal Inc.Dual-pane thermal window with liquid crystal shade
US5111629 *Apr 18, 1991May 12, 1992Allied-Signal Inc.Dual-pane thermal window with liquid crystal shade
US5152111 *Mar 9, 1992Oct 6, 1992Allied-Signal Inc.Dual-pane thermal window with liquid crystal shade
US5193900 *Feb 28, 1992Mar 16, 1993Matsushita Electric Industrial Co., Ltd.Illumination device
US5196705 *Aug 23, 1991Mar 23, 1993Saitek LimitedSun exposure monitoring device
US5197242 *Jul 17, 1992Mar 30, 1993Allied-Signal Inc.Dual-pane thermal window with liquid crystal shade
US5308706 *Jan 15, 1993May 3, 1994Nippon Sheet Glass Co., Ltd.Heat reflecting sandwich plate
US5319242 *Mar 18, 1992Jun 7, 1994Motorola, Inc.Semiconductor package having an exposed die surface
US5319478 *Oct 26, 1990Jun 7, 1994Hoffmann-La Roche Inc.Light control systems with a circular polarizer and a twisted nematic liquid crystal having a minimum path difference of λ/2
US5377042 *Dec 20, 1993Dec 27, 1994Chahroudi; DayStructure and preparation of automatic light valves
US5481400 *Nov 9, 1993Jan 2, 1996Hughes Aircraft CompanySurvivable window grids
US5525430 *Oct 18, 1993Jun 11, 1996Chahroudi; DayElectrically activated thermochromic optical shutters
US5574286 *Jun 30, 1995Nov 12, 1996Huston; Alan L.Solar-blind radiation detector
US5686979 *Jun 26, 1995Nov 11, 1997Minnesota Mining And Manufacturing CompanyOptical panel capable of switching between reflective and transmissive states
US5881200 *Sep 29, 1995Mar 9, 1999British Telecommunications Public Limited CompanyOptical fibre with quantum dots
US5889288 *Jul 22, 1996Mar 30, 1999Fujitsu LimitedSemiconductor quantum dot device
US5897957 *Dec 17, 1996Apr 27, 1999Libbey-Owens-Ford Co.Coated glass article having a solar control coating
US5940150 *Feb 26, 1997Aug 17, 1999Reveo, Inc.Electro-optical glazing structures having total-reflection and transparent modes of operation for use in dynamical control of electromagnetic radiation
US5986730 *Dec 1, 1998Nov 16, 1999MoxtekDual mode reflective/transmissive liquid crystal display apparatus
US6049419 *Jan 13, 1998Apr 11, 20003M Innovative Properties CoMultilayer infrared reflecting optical body
US6099758 *Sep 16, 1998Aug 8, 2000Merck Patent Gesellschaft Mit Beschrankter HaftungBroadband reflective polarizer
US6122103 *Jun 22, 1999Sep 19, 2000MoxtechBroadband wire grid polarizer for the visible spectrum
US6218018 *Feb 16, 1999Apr 17, 2001Atofina Chemicals, Inc.Solar control coated glass
US6281519 *Mar 22, 1999Aug 28, 2001Fujitsu LimitedQuantum semiconductor memory device including quantum dots
US6288840 *Jan 11, 2000Sep 11, 2001MoxtekImbedded wire grid polarizer for the visible spectrum
US6294794 *Feb 4, 1998Sep 25, 2001Fujitsu LimitedNon-linear optical device using quantum dots
US6391400 *Apr 8, 1998May 21, 2002Thomas A. RussellThermal control films suitable for use in glazing
US6486997 *May 17, 1999Nov 26, 20023M Innovative Properties CompanyReflective LCD projection system using wide-angle Cartesian polarizing beam splitter
US6486999 *Mar 15, 2000Nov 26, 2002Agere Systems Inc.Using crystalline materials to control the thermo-optic behavior of an optical path
US6493482 *Nov 22, 2000Dec 10, 2002L3 Optics, Inc.Optical switch having a planar waveguide and a shutter actuator
US6504588 *Apr 28, 1999Jan 7, 2003Citizen Watch Co., Ltd.Reflection-type color liquid crystal display device having absorbing member containing fluorescent material
US6512242 *Jan 11, 1999Jan 28, 2003Massachusetts Institute Of TechnologyResonant-tunneling electronic transportors
US6559903 *Feb 27, 1998May 6, 2003Reveo, Inc.Non-absorptive electro-optical glazing structure employing composite infrared reflective polarizing filter
US6565982 *Jun 28, 1996May 20, 20033M Innovative Properties CompanyTransparent multilayer device
US6577360 *Jul 10, 1998Jun 10, 2003Citizen Watch Co., Ltd.Liquid crystal display
US6583827 *Jul 15, 1999Jun 24, 2003Reveo, Inc.Electro-optical glazing structures having bi-directional control of electromagnetic radiation during total-reflection, semi-transparent and totally-transparent modes of operation
US6624936 *May 10, 2001Sep 23, 20033M Innovative Properties CompanyColor-compensated information displays
US6661482 *Oct 5, 2001Dec 9, 2003Nitto Denko CorporationPolarizing element, optical element, and liquid crystal display
US6671008 *Apr 6, 2000Dec 30, 2003Reveo, Inc.Electro-optical glazing structures having scattering and transparent modes of operation and methods and apparatus for making the same
US6710823 *Nov 6, 2001Mar 23, 2004Reveo, Inc.Electro-optical glazing structures having reflection and transparent modes of operation
US6912018 *Jun 23, 2003Jun 28, 2005Inventqjaya Sdn. Bhd.Electro-optical glazing structures having total-reflection and transparent modes of operation for use in dynamical control of electromagnetic radiation
US6965420 *Sep 5, 2003Nov 15, 2005Reveo, Inc.Spectrum-controllable reflective polarizers having electrically-switchable modes of operation
US6978070 *Sep 26, 2001Dec 20, 2005The Programmable Matter CorporationFiber incorporating quantum dots as programmable dopants
US7038745 *Feb 19, 2003May 2, 20063M Innovative Properties CompanyBrightness enhancing reflective polarizer
US7042615 *May 19, 2003May 9, 2006The Regents Of The University Of CaliforniaElectrochromic devices based on lithium insertion
US7049004 *Sep 19, 2003May 23, 2006Aegis Semiconductor, Inc.Index tunable thin film interference coatings
US7057681 *Jun 24, 2003Jun 6, 2006Seiko Epson CorporationLiquid crystal display with mirror mode having top reflective polarizer
US7099062 *Sep 26, 2002Aug 29, 2006Forskarpatent I Uppsala AbElectrochromic film and device comprising the same
US7113335 *Dec 11, 2003Sep 26, 2006Sales Tasso RGrid polarizer with suppressed reflectivity
US7133335 *May 3, 2004Nov 7, 2006Hitachi, Ltd.Wobble signal reproducing circuit
US7166797 *Aug 14, 2002Jan 23, 2007The United States Of America As Represented By The United States Department Of EnergyTandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system
US7276432 *Mar 16, 2005Oct 2, 2007The Programmable Matter CorporationFiber incorporating quantum dots as programmable dopants
US7300167 *Dec 9, 2005Nov 27, 2007Lct Enterprises, LlcAdjustably opaque window
US7525604 *Mar 15, 2006Apr 28, 2009Naxellent, LlcWindows with electrically controllable transmission and reflection
US7755829 *Jul 13, 2010Ravenbrick LlcThermally switched reflective optical shutter
US7768693 *Aug 3, 2010Ravenbrick LlcThermally switched optical downconverting filter
US20020079485 *Sep 20, 2001Jun 27, 2002Andreas StintzQuantum dash device
US20020114367 *Oct 5, 2001Aug 22, 2002Andreas StintzQuantum dot lasers
US20030066998 *Aug 2, 2002Apr 10, 2003Lee Howard Wing HoonQuantum dots of Group IV semiconductor materials
US20040213314 *Apr 21, 2004Oct 28, 2004Mitsubishi Denki Kabushiki KaishaSemiconductor laser device
US20060011904 *Jun 3, 2005Jan 19, 2006Snyder Gary ELayered composite film incorporating quantum dots as programmable dopants
US20080061222 *Sep 12, 2007Mar 13, 2008The Programmable Matter CorporationElectromagnetic sensor incorporating quantum confinement structures
US20080210893 *Jan 24, 2008Sep 4, 2008Ravenbrick, LlcThermally switched optical downconverting filter
US20090015902 *Jul 11, 2008Jan 15, 2009Powers Richard MThermally Switched Reflective Optical Shutter
US20090128893 *Sep 19, 2008May 21, 2009Ravenbrick, LlcLow-emissivity window films and coatings incorporating nanoscale wire grids
US20090167971 *Dec 19, 2008Jul 2, 2009Ravenbrick, LlcThermally switched absorptive window shutter
US20090167972 *Feb 24, 2009Jul 2, 2009Jin Cheol HongLiquid crystal display device
US20090219603 *May 19, 2008Sep 3, 2009Jiuzhi XueTemperature activated optical films
US20090284670 *Apr 27, 2009Nov 19, 2009Jiuzhi XueWindows with electrically controllable transmission and reflection
US20100271686 *Oct 28, 2010Ravenbrick LlcThermally switched reflective optical shutter
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7973998May 19, 2008Jul 5, 2011Serious Materials, Inc.Temperature activated optical films
US8072672 *Dec 6, 2011Ravenbrick LlcThermally switched reflective optical shutter
US8076661Jul 26, 2010Dec 13, 2011Ravenbrick LlcThermally switched optical downconverting filter
US8102478Jan 24, 2012Serious Energy, Inc.Windows with electrically controllable transmission and reflection
US8169685May 1, 2012Ravenbrick, LlcThermally switched absorptive window shutter
US8284336Oct 9, 2012Ravenbrick LlcThermally switched optical filter incorporating a guest-host architecture
US8593581May 13, 2011Nov 26, 2013Ravenbrick LlcThermally switched optical downconverting filter
US8634137Apr 23, 2009Jan 21, 2014Ravenbrick LlcGlare management of reflective and thermoreflective surfaces
US8643795Oct 13, 2010Feb 4, 2014Ravenbrick LlcThermally switched optical filter incorporating a refractive optical structure
US8665414Aug 20, 2009Mar 4, 2014Ravenbrick LlcMethods for fabricating thermochromic filters
US8699114Jun 1, 2011Apr 15, 2014Ravenbrick LlcMultifunctional building component
US8755105Dec 5, 2011Jun 17, 2014Ravenbrick LlcThermally switched reflective optical shutter
US8760750Apr 25, 2012Jun 24, 2014Ravenbrick LlcThermally switched absorptive window shutter
US8828176Mar 29, 2011Sep 9, 2014Ravenbrick LlcPolymer stabilized thermotropic liquid crystal device
US8867132Oct 29, 2010Oct 21, 2014Ravenbrick LlcThermochromic filters and stopband filters for use with same
US8908267Sep 19, 2008Dec 9, 2014Ravenbrick, LlcLow-emissivity window films and coatings incorporating nanoscale wire grids
US8947760 *Aug 31, 2012Feb 3, 2015Ravenbrick LlcThermotropic optical shutter incorporating coatable polarizers
US9116302Jun 19, 2009Aug 25, 2015Ravenbrick LlcOptical metapolarizer device
US9188804Mar 4, 2014Nov 17, 2015Ravenbrick LlcMethods for fabricating thermochromic filters
US9233572 *Aug 30, 2013Jan 12, 2016International Business Machines CorporationAnti-counterfeiting opto-thermal watermark for electronics
US9256085Apr 14, 2014Feb 9, 2016Ravenbrick LlcMultifunctional building component
US9296246 *Dec 11, 2013Mar 29, 2016International Business Machines CorporationAnti-counterfeiting opto-thermal watermark for electronics
US20090128893 *Sep 19, 2008May 21, 2009Ravenbrick, LlcLow-emissivity window films and coatings incorporating nanoscale wire grids
US20090167971 *Dec 19, 2008Jul 2, 2009Ravenbrick, LlcThermally switched absorptive window shutter
US20090219603 *May 19, 2008Sep 3, 2009Jiuzhi XueTemperature activated optical films
US20090284670 *Apr 27, 2009Nov 19, 2009Jiuzhi XueWindows with electrically controllable transmission and reflection
US20100045924 *Aug 20, 2009Feb 25, 2010Ravenbrick, LlcMethods for Fabricating Thermochromic Filters
US20100232017 *Sep 16, 2010Ravenbrick LlcOptical metapolarizer device
US20100259698 *Oct 14, 2010Ravenbrick LlcThermally Switched Optical Filter Incorporating a Guest-Host Architecture
US20100271686 *Oct 28, 2010Ravenbrick LlcThermally switched reflective optical shutter
US20100288947 *Nov 18, 2010Ravenbrick LlcThermally switched optical downconverting filter
US20110025934 *Feb 3, 2011Ravenbrick LlcThermally switched optical filter incorporating a refractive optical structure
US20110102878 *May 5, 2011Ravenbrick LlcThermochromic Filters and Stopband Filters for Use with Same
US20110205650 *Aug 25, 2011Ravenbrick LlcWavelength-Specific Optical Switch
US20110216254 *Sep 8, 2011Ravenbrick LlcThermally Switched Optical Downconverting Filter
US20110234944 *Sep 29, 2011Ravenbrick LlcPolymer-stabilized thermotropic liquid crystal device
US20130033738 *Feb 7, 2013Ravenbrick LlcThermally switched optical filter incorporating a guest-host architecture
US20130141774 *Aug 31, 2012Jun 6, 2013Wil McCarthyThermotropic optical shutter incorporating coatable polarizers
US20150061278 *Aug 30, 2013Mar 5, 2015International Business Machines CorporationAnti-counterfeiting opto-thermal watermark for electronics
US20150061279 *Dec 11, 2013Mar 5, 2015International Business Machines CorporationAnti-counterfeiting opto-thermal watermark for electronics
Classifications
U.S. Classification359/289, 359/352, 359/359
International ClassificationG02B5/30, G02F1/19
Cooperative ClassificationG02B5/285, G02B5/3016, G02F1/0147, G02F1/21, G02B5/287
European ClassificationG02B5/28F, G02B5/28F2, G02B5/30L, G02F1/21
Legal Events
DateCodeEventDescription
Aug 10, 2011ASAssignment
Owner name: SERIOUS MATERIALS, INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NAXELLENT, LLC;REEL/FRAME:026729/0660
Effective date: 20090420
Owner name: NAXELLENT, LLC, COLORADO
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:XUE, JIUZHI;REEL/FRAME:026729/0308
Effective date: 20070525
Dec 14, 2011ASAssignment
Owner name: SERIOUS ENERGY, INC., CALIFORNIA
Free format text: MERGER;ASSIGNOR:SERIOUS MATERIALS, INC.;REEL/FRAME:027379/0410
Effective date: 20110531