Liquid crystal cells – elements and systems – With specified nonchemical characteristic of liquid crystal... – Within cholesteric phase
Reexamination Certificate
2000-02-14
2003-03-18
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
With specified nonchemical characteristic of liquid crystal...
Within cholesteric phase
C427S212000, C428S402000
Reexamination Certificate
active
06535268
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention is the field of protective coatings for protecting surfaces from injurious ambient light.
BRIEF DESCRIPTION OF THE LITERATURE
Broadband reflecting polarizers were introduced in application Ser. No. 08/550,022 (now U.S. Pat. No. 5,691,789) entitled “Single Layer Reflective Super Broadband Circular Polarizer and Method of Fabrication Therefor” by Sadeg M. Faris and Le Li which was filed Oct. 30, 1995. Such broadband polarizers are made by producing a single layer having cholesteric liquid crystal order where the pitch of the liquid crystal order varies in a non linear fashion across the layer.
General references on polymer dispersed liquid crystals may be found in detail in “Polymer Dispersed Liquid crystal displays”, by J. W. Doane, a chapter in “Liquid Crystals”, Ed. B. Bahadur, World Scientific Publishing, Singapore, and “CLC/polymer dispersion for haze-free light shutters, by D. Yang et al. Appl. Phys. Lett. 60, 3102 (1992).
Since the early attempt of utilizing cholesteric film as optical filters and the effort on polymer encapsulated nematic liquid crystals for display, much attention has been focused on trying to bring polymeric liquid crystals and cholesteric liquid crystals together to make devices for light control application. (See, for example J. Adams, W. Hass, J. Dailey, Journal of Applied Physics, 1971, and J. L. Fergason, Society for Information Display Digest, 1985.).
The following applications are related to the present invention: application Ser. No. 9/093,017 filed Jun. 5, 1998; application Ser. No. 09/093,006 filed May 5, 1998; application Ser. No. 09/039,303 filed Mar. 14, 1998; application Ser. No. 09/039,297 filed Mar. 14, 1998; application Ser. No. 08/891,877 filed Jul. 9, 1997 entitled “Reflective Film Material Having Symmetrical Reflection Characteristics and Method and Apparatus for Making the Same”, by Le Li and Sadeg Faris; application Ser. No. 08/739,467 filed Oct. 29, 1996 entitled “Circularly Polarizing Reflective Material Having Super Broad-Band Reflecting & Transmission Characteristics & Method of Fabricating & Using Same in Diverse Applications” by Sadeg M. Faris, Le Li, and Yingqiu Jiang Jiang; application Ser. No. 08/890,320 filed Jul. 9, 1997 entitled “Coloring Media Having Improved Brightness and Color Characteristics” by Sadeg M. Faris and Le Li; The above identified US patents and other references are hereby incorporated by reference .
BACKGROUND OF THE INVENTION
Protection of surfaces from injurious effects of ambient light has heretofore generally used materials which absorbed the injurious light. Organic molecules used as sunscreens are chosen to have a very strong absorption in a particular band. For example, the absorption in the UVA band. Unfortunately, the absorption is usually not great in additional bands such as the UVB band. Unfortunately, the materials which absorb injurious light also tend to be “injured” by the light. For example, organic molecules applied to the skin as sunscreen tend to break down when subjected to strong ultraviolet light for a long time. In addition, such materials added to plastics and fabrics tend also to have limited life. Reflecting and scattering materials, such as zinc oxide used in sunscreens, tend to reflect and scatter visible light also, which leads to the faintly comical “white noses” familiar on lifeguards.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a protective material which protects the surface of a material from injurious ambient light. It is a further object of the invention to provide a protective material which reflects the injurious ambient light. It is a further object of the invention to provide a protective material which is transparent in the visible spectral region. It is a further object of the invention to provide a protective material which reflects injurious ultraviolet light. It is a further object of the invention to provide a protective material which reflects both injurious ultraviolet light and infrared light. It is a further object of the invention to provide a protective material which acts as a sunscreen for human skin and which is not visible in visible light.
SUMMARY OF THE INVENTION
Non metallic, reflecting flakes of multilayer polymer, CLC, or inorganic material are used with a binder to form a protective coating on a material surface. The flakes reflect light in a spectral range where the light is injurious to the material surface, and transmit light in a spectral range where the light is not injurious to the material surface.
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Faris Sadeg
Li Le
Crispino Ralph J.
Hodgson Rodney T.
Parker Kenneth
Reveo Inc.
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