Abstract:
An electronically shaded glass window shading system is described that provides a progressively darkening window, based on either user input or detection of ambient light. The electronically shaded glass window shading system may be used for commercial buildings, residential buildings, public areas, and vehicles. The electronically shaded glass window shading system may enhance energy efficiency by blocking bright light thereby reducing heat. The electronically shaded glass window shading system includes a user interface that permits a user to create opaque or alternatively transparent walls or windows as the need arises.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a Continuation-in-Part of U.S. patent application Ser. No. 10/430,877, filed on May 6, 2003, the disclosure of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates generally to shadable transparent window shading systems. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    In order to depict the manner in which the embodiments are obtained, a more particular description of embodiments briefly described above will be rendered by reference to exemplary embodiments that are illustrated in the appended drawings. These drawings depict typical embodiments that are not necessarily drawn to scale and are not therefore to be considered to be limiting of its scope. The embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0004]      FIG. 1  is a cross-section schematic view of a transparent laminated window shading system according to an embodiment; 
           [0005]      FIG. 2  is a block diagram of components and interrelationships of a transparent laminated window shading system according to an embodiment; 
           [0006]      FIG. 3  is a cross-section view of a transparent laminated window shading system according to an embodiment; and 
           [0007]      FIG. 4  is a detail section taken from  FIG. 1  according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    This disclosure relates to window devices that use electronically controlled liquid crystal material to selectively modify the transparency of the otherwise transparent window material. More specifically, embodiments relate to window devices that use electronically controlled liquid crystal material that provides control of the transparency by application of a phase-controlled, frequency modulated current. 
         [0009]    A window is provided with an integrated window shading system. The window has progressive shading through the use of liquid crystal display lamination material located between two panes of window glass. 
         [0010]    A window shading system embodiment includes an integral liquid crystal material such as a thin-film technology (TFT) monochromatic dyed liquid crystal material that is positioned between two transparent panes of window glass, plastic, transparent aluminum, or the other substrates. Along with several other components, the dyed liquid crystal material provides a mechanism for progressively darkening the window shading system. In an embodiment the darkening of an entire windowpane is accomplished without the use of mechanical shades, blinds, drapes or other window coverings. The darkening of the window limits the amount of heat transmitted through the window by sunlight, provides a privacy shield, and minimizes glare. 
         [0011]    Embodiments may be used in commercial office buildings, in residential buildings, and in public wall areas In an embodiment the window shading system is installable in automobiles, aircraft, space craft, and other vehicles where the control of the window shading system can be set to automatically darken the windows as daylight levels of sunlight increases and to lighten the windows as direct sunlight decreases through the day. 
         [0012]    In an embodiment a user controller is provided to permit the user to set the desired amount of opacity. In an embodiment a user controller is provided to program the degree of change in opacity in response sunlight. In an embodiment a user controller is provided to rotate the plane of polarization so that circularly polarized light, also known as glare, is transmitted so as to reduce the effect of the glare. 
         [0013]      FIG. 1  is a cross-section schematic view of a transparent laminated window shading system  100  according to an embodiment. Two substrates  102  and  109 , which are transparent panels  102  and  109 , are held within a frame  101 . In an embodiment the transparent panels  102  and  109  are composed of transparent aluminum, which is sintered corundum (α-Al 2 O 3 ) with micro meter nano-structures on the inner surfaces thereof, such as is produced by Fraunhoffer Institute for Ceramic Technologies. In an embodiment glass may be provided for both, or at least one, of the transparent panels  102  and  109 . In an embodiment polycarbonate material may be provided for both, or at least one, of the transparent panels  102  and  109 . In an embodiment a transparent plastic may be provided for both, or at least one, of the transparent panels  102  and  109 . In an embodiment the panels  102  and  109  may include polarizing filter qualities. In an embodiment the polarizing filter qualities may be present as surface-applied films upon the transparent panels  102  and  109 . In an embodiment the panels  102  and  109  may be translucent. 
         [0014]    According to an embodiment one surface of each transparent panel  102  and  109  is coated with a thin layer of an optically transparent electrically conductive layer  103  and  108 , respectively. In an embodiment the layers of electrically conductive layer  103  and  108  is a Indium Tin Oxide (ITO). In an embodiment a different electrically conductive material  103  and  108  may be used. Each transparent panel  102  and  109  carries a transparent coating of the ITO that is etched to provide a pattern where the liquid crystal can be activated by an electric field. In an embodiment the resistance of the ITO is in the range from about 15 Ohm/sq to about 50 Ohm/sq. 
         [0015]    A pair of gaps  104  and  107  are provided between the respective transparent panels  102  and  109  by spacers  106   a  and  106   b . In an embodiment the gaps  104  and  107  are in a size range from about 3 nm (nanometer) to about 4 μm in width. The spacers  106   a  and  106   b  may be located in a manner, as shown here, within the frame so as to not be visible. The spacers  106   a  and  106   b  provide the a spacing between the transparent panels  102  and  109 , as well as the gaps  104  and  107  between the transparent panels  102  and  109 , and a liquid crystal panel  105 . 
         [0016]      FIG. 4  is a detail section  4  taken from  FIG. 1  according to an embodiment. In an embodiment where the transparent panel  102  is coated with an electrically conductive layer  103  such as the ITO, a thin (70 nm) dielectric layer  120  such as a silicon dioxide coating, the dielectric layer  120  acts as an insulation layer. On top of the dielectric layer  120  is a thin (50 nm) polymer layer  122  such as a polyimide. Such polyimides may be silica electroconductive (SE) materials that can be obtained from Nissan Chemicals such as SE-1211. The polymer layer  122  is affective to align the molecules of the liquid crystal material nematic phase in a homeotropic alignment with the long axis of the anisotropic molecules configured perpendicular to the substrate, and thus the viewing direction of the device. Accordingly, an observer may look along the optical axis of the nematic liquid crystal phase and thus light is essentially not interacted with by the liquid crystal. 
         [0017]    Referring again to  FIG. 1 , the liquid crystal panel  105  contains a dyed liquid crystal. In a process embodiment the dyed liquid crystal is inserted by capillary action to fill the space defined by the spacers  106   a  and  106   b  and the transparent panels  102  and  109 . In an embodiment, the dyed material is inserted into the vacuum space inside the liquid crystal panel  105 . In an embodiment, the dyed material is inserted into the vacuum space inside the liquid crystal panel  105  and also between the each layer of ITO  103  and  108  such that the dyed material is contained within the space created by the spacers  106   a  and  106   b  between the transparent panels  102  and  109 . 
         [0018]    In an embodiment a black dye is used to dye the liquid crystal. In an embodiment a black dichroic (capable of exhibiting two shades) dye mixture such as from Mitsui Chemicals America, is dissolved in a chiral nematic liquid crystal of negative dielectric anisotropy. In an embodiment, the dye is about 4% S344 dye, a black dichroric dye manufactured by Mitsui Chemical America (Mitsui Toatsu Dyes), and the liquid crystal is about 20% by weight ZLI 3401 positive dielectric nematic liquid crystal, manufactured by Merck GmbH, Darmstatdt, Germany. 
         [0019]    In an embodiment the negative dielectric anisotropy of the liquid crystal is Δ∈=&lt;−3. The negative dielectric anisotropy liquid crystal also may have a low birefringence such as Δn=0.06. Such negative dielectric anisotropy liquid crystal materials may be obtained from Merck GmbH of Germany. Such negative dielectric anisotropy liquid crystal materials may have an operable temperature range from about negative 20° C. to about positive 75° C. The chiral liquid crystal is configured to be optically active for at least ultraviolet light. The required chirality is imparted by adding a suitable optically active material such as a compound of similar molecular structure to a liquid crystal but in which there is one or more chiral centers that impart a helical twist to the chiral nematic phase. This may create a long pitch chiral nematic phase that is suitable for the several embodiments. 
         [0020]    In an embodiment the pitch of this chiral nematic phase is about the same width as the gap between the two transparent panels  102  and  109 . Similarly, the pitch of the chiral nematic phase is about the same width created between the thin layers of electrically conductive material such as the electrically conductive material  103  and  108  embodiments. 
         [0021]    In an embodiment the pitch of the chiral nematic phase is larger than the gap by a fraction of 0.9. In an embodiment the pitch of the chiral nematic phase is smaller than the gap. In an embodiment the pitch of the chiral nematic phase is smaller than the gap by a fraction of 0.9. In an embodiment the pitch of the chiral nematic phase is smaller than the gap by a fraction of 0.95. In an embodiment the pitch of the chiral nematic phase is smaller than the gap by a fraction of 0.97. In an embodiment the pitch of the chiral nematic phase is smaller than the gap by a fraction of 0.99. In an embodiment the pitch of the chiral nematic phase is smaller than the gap by a fraction of 0.999. 
         [0022]    In an embodiment the dye that is used is at least one anthraquinone compound. It can be generically represented by the structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    Anthraquinone is also referred to as 9,10-dioxoanthracene. Anthraquinone may be derived from anthracene. Anthraquinone may also be referred to as 9,10-anthracenedione, anthradione, 9,10-anthrachinon, anthracene-9,10-quinone, 9,10-dihydro-9,10-dioxoanthracene. It has the appearance of yellow or light gray to gray-green solid crystalline powder. 
         [0023]    In an embodiment the dye that is used is an azo compound. It can be generically represented by the structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    Azo compound embodiments have the functional group R—N═N—R′, in which R and R′ can be either aryl or alkyl. The N═N group is called the azo or a diimide. 
         [0024]    In an embodiment the azo compound Sudan Black B is used. Sudan Black B has the chemical structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    Sudan Black B (C 26 H 24 N 4 O) is a lysochrome (fat-soluble dye) diazo dye. It has the appearance of a dark brown to black powder with maximum absorption at 596-605 nm and a melting point 120° C. to 124° C. It stains blue-black. 
         [0025]    In an embodiment the azo compound Amidio Black is used. Amidio Black has the chemical structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    Amido black 10B, 4-Amino-5-hydroxy-3-[(4-nitrophenyl)azo]-6-1-(phenylazo)-2,7-Naphthalene disulfonic acid, disodium salt, is also called Amidoschwarz, Naphthol blue black, Acid Black 1, Acidal Black 10B, Acidal Navy Blue 3BR, Naphthalene Black 10B, Buffalo Black NBR, and C.I. 20470, is an amino acid staining diazo dye. 
         [0026]    In an embodiment the azo compound Janus Green is used. Janus Green has the chemical structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0027]    Janus Green may be represented by C 30 H 31 N 6 Cl, or diethylsafraninazodimethylaniline chloride. 
         [0028]    In an embodiment the dye that is used an azulene compound. It can be generically represented by the structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    Azulene is an isomer of naphthalene and is a dark blue crystalline solid. 
         [0029]    Other dichroric dyes may be used depending upon a specific application. Such dyes may include merocyanine compounds. Other such dyes may include tetraline compounds. 
         [0030]    In an embodiment more than one dye may be dissolved into the liquid crystal matrix. Whereas one specific dichroric dye may be selected, a second dye may be selected to assist in achieving sufficient opacity or hue for a given application. 
         [0031]    In an embodiment the liquid crystal matrix has been doped with at least one dye such that the liquid crystal matrix is about 5% dye. In an embodiment the liquid crystal matrix has been doped with at least one dye such that the liquid crystal matrix is about 4% dye. In an embodiment the liquid crystal matrix has been doped with at least one dye such that the liquid crystal matrix is about 3% dye. In an embodiment the liquid crystal matrix has been doped with at least one dye such that the liquid crystal matrix is about 2% dye. In an embodiment the liquid crystal matrix has been doped with at least one dye such that the liquid crystal matrix is about 1% dye. In an embodiment the liquid crystal matrix has been doped with at least one dye such that the liquid crystal matrix is about 0.5% dye. In an embodiment the liquid crystal matrix has been doped with at least one dye such that the liquid crystal matrix is about 0.1% dye. 
         [0032]    Each substrate carries a transparent coating of indium tin oxide (ITO) that is etched to provide a pattern that is where the liquid crystal will be activated by an electric field. The resistance of the ITO is typically in the range 15-50 Ohm/sq. 
         [0033]    Without any applied electric field, the liquid crystal is in the homeotropic state. This means the helical nature of the liquid crystal is effectively unwound by the surface effects under these cell conditions. In the homeotropic state, only the dichroic dye will have any influence on the light. Due to the dye molecules not being perfectly aligned largely due to thermal motion of the liquid crystal, some light will be absorbed by the dye. This reduces the transmission of the thin film dependant on the amount of dye used and the size of the cell gap. 
         [0034]    In an embodiment an alternating current (AC) electric field in a range of about 6 Volt to about 10 Volt is applied across a cell gap in a range from about 4 μm to about 6 μm. The liquid crystal molecules align to reduce the interaction of the electric field and the higher dielectric constant of the molecules (which is across the short axis of the anisotropic molecules) such that the long axis of molecules gradually aligns perpendicular to the electric field, which is parallel to the substrates. This transition occurs over a few volts typically between 1.8Volt and 4.5Volt and allows a range of partial-tone levels (such as grey for a black dye) to be observed. With a black dye, the appearance of the cell gradually changes from pale grey to dark grey (black) when the electrical field is applied. 
         [0035]    Accordingly, an embodiment provides an integrated window shading system that provides a mechanism for progressively darkening the view port defined by the window. Another embodiment provides an integrated window shading system that provides a mechanism for darkening some or all of a pane of glass through the use of liquid crystal display lamination material. An embodiment provides an integrated window shading system that can control the transfer of heat (infra-red) transmitted into an enclosure through the window by brilliant sunlight. An embodiment provides an integrated window shading system that is electronically controllable by a user. The difference in transmission between an applied electrical field and no applied electrical field is the contrast ratio and may depend upon the dye concentration, the gap sizes, the type of electrically conductive layers, and others. 
         [0036]    In an example embodiment a 2.9% dye doping is used, and the CR is 5.7:1 with 53% light transmission. In an embodiment a 2.4% dye doping is used, and the light transmission increases but the CR is lower at 4:1. Thus the CR and transmission can be changed. 
         [0037]    When the electrical field is removed, the liquid crystal is restored to the homeotropic alignment, likely due to surface effects, although there may be other causes. In an embodiment the restored homeotropic alignment occurs in a time range from about 60 milliseconds (ms) to about 80 ms when the field switched off abruptly. In a method embodiment the electrical field is reduced gradually, and the opacity of the window shading system diminishes proportionally. 
         [0038]    In an embodiment the dyed liquid crystal panel  105  is formulated to allow about 90% circularly polarized light to pass through with transparency. By applying a properly modulated voltage across the dyed LCD material  105  sandwiched between the transparent panels  102  and  109 , the molecules of the LCD material  105  are reoriented relative to the panes of transparent panels  102  and  109  to reduce the total light transmissivity and/or to reduce glare by altering the plane of polarization of the light which is permitted to pass through the window shading system  100 . An embodiment provides an integrated window shading system that provides a controllable privacy shield. An embodiment provides an integrated window shading system that provides a mechanism for minimizing glare. An embodiment provides an integrated window shading system that provides rapid user-controllable or automatic-controlled darkening of the window in response to increases in light intensity. Another embodiment provides an integrated window shading system that reduces glare without significantly reducing transparency or light transmissivity of the window. An embodiment provides an integrated window shading system that is compatible with use in buildings and/or vehicles. 
         [0039]    Electrical contacts (in this embodiment two contacts)  110   a  and  110   b  are connected to the electrically conductive layers  108  and  103  of the transparent panels  102  and  109 . As depicted, one electrical contact  110   a  and  110   b  is connected to the respective electrically conductive layers  103  and  108 . In an embodiment additional contacts may be used to couple the electrically conductive layer  103  and  108  to external circuitry. The electrical contacts  110   a  and  110   b  are connected at contacts  114   a  and  114   b  to an electrical signal source that powers a control circuit  111 . 
         [0040]    In an embodiment the control circuit  111  provides at least one of an intensity, waveform, amplitude, frequency, and phase modulated voltage signal that is specifically adapted to modulate the transparency and/or polarization of the dyed liquid crystal material. The modulated voltage signal is controlled by a modulation circuit within the control circuit  111 . A power supply  112  is provided to the control circuit  111 . 
         [0041]    In an embodiment one or more photovoltaic films  113   a  and  113   b  are provided to convert ambient sunlight to electric current sufficient to power the window shading system, while the sun is shining without the need for, or to augment, batteries or externally supplied power sources. 
         [0042]    In an embodiment the dyed liquid crystal material is connected to an electronic controller that is specifically adapted to gradually darken the dyed liquid crystal material by application of a phase-controlled and frequency modulated direct voltage current. The window shading system may provide 100% or near 100% transparency when no voltage is applied. Similarly the window shading system may darken to near complete opacity. 
         [0043]      FIG. 2  is a block diagram of components and interrelationships of a transparent laminated window shading system according to an embodiment. The shadable window unit  201  receives control signals from a controller  203 , which is powered by a power supply  205 . A sensor  202  may be provided for detecting the amount of ambient light. A user interface  204  may be provided in communication with the controller  203 . The shadable window unit  201  includes the dyed liquid crystal panel sandwiched between the transparent panels as shown in  FIG. 1 . The controller  203  includes a programmable microprocessor device and the modulation circuit. 
         [0044]    The user interface  204 , includes the capability to permit a user to manually darken on demand the transmissivity of the window shading system  100 , as well as to program the controller  203 . The user interface  204  may be electrically connected to the controller  203 , or alternatively, may by a wireless remote controller. 
         [0045]    The power supply  205  may include an AC power connection, a battery device, and/or a photovoltaic cell along with the conversion and storage circuitry required for applying power to the system. The sensor  202  may be a photo sensor suitable to detecting the luminance of the ambient light. In some embodiments, the sensor  202  may also detect brightness, intensity, and wavelength of the ambient light. 
         [0046]      FIG. 3  is a cross-section view of a transparent laminated window shading system according to an embodiment. In this embodiment a transparent or semi-transparent photovoltaic film  312  is applied to the outer surface of the first transparent panel  309 , the other surface of which has applied the conductive layer  308 . The spacers  306   a  and  306   b  provide the gaps  307  and  304  between the transparent panels  309  and  302  and a dyed liquid crystal panel  305  that is sandwiched between the transparent panels  309  and  302 . The second transparent panel  302  is also provided with a conductive layer  303 . The photovoltaic film  312  is electrically connected  313  to the control circuit  311 , which in turn is electrically connected to contacts  310   a  and  310   b  to the conductive layers  303 ,  308 . The entire assembly  300  is held in place in frame  301 . 
         [0047]    The above-described embodiments and examples are merely illustrative of numerous and varied other embodiments and applications which may constitute applications of the principles of the several embodiments. These above-described embodiments are provided to teach the present best mode of the several embodiments only, and should not be interpreted to limit the scope of the claims. Such other embodiments may use somewhat different steps and routines which may be readily devised by those skilled in the art without departing from the scope of the several embodiments. 
         [0048]    The Abstract is provided to comply with 37 C.F.R. § 1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together to streamline the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may lie in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.