PATENT DOCUMENT

Publication Number: US-12090821-B1
Application Number: US-202117364209-A
Country: US
Kind Code: B1

Title: Systems with adjustable window transmission

Abstract:
A system such as a vehicle, building, or electronic device system may have a support structure with one or more windows. The support structure and window may separate an interior region within the system from a surrounding exterior region. Control circuitry may receive input such as user input and may adjust an adjustable layer in the window based on the input. The adjustable layer may be an adjustable light transmission layer. The adjustable light transmission layer may have a polymer matrix layer with embedded guest-host liquid crystal cells. Each cell may have liquid crystal material and dichroic dye. The adjustable light transmission layer may be operated in a dark state to prevent light from passing through the window, a clear state in which the window passes light, and intermediate states that exhibit intermediate light transmission levels.

Claims:
What is claimed is: 
     
       1. A vehicle window configured to separate an interior region from an exterior region, comprising:
 a first structural window layer; 
 a second structural window layer; and 
 an adjustable transmission layer between the first and second structural window layers, wherein the adjustable transmission layer comprises a layer of polymer matrix with embedded guest-host liquid crystal nanosized cells droplets, and wherein each of the embedded guest-host liquid crystal nanosized droplets contains liquid crystal and guest dye molecules. 
 
     
     
       2. The window defined in  claim 1  wherein the adjustable transmission layer comprises first and second transparent conductive electrodes on opposing first and second sides of the layer of polymer matrix. 
     
     
       3. The window defined in  claim 2  wherein the embedded guest-host liquid crystal nanosized droplets have diameters of less than 200 nm. 
     
     
       4. The window defined in  claim 2  wherein the layer of polymer matrix has a first refractive index, wherein the embedded guest-host liquid crystal nanosized droplets have a second refractive index, and wherein the first and second refractive indices differ by less than 0.1. 
     
     
       5. The window defined in  claim 2  wherein the layer of polymer matrix has a thickness of 8 to 20 microns. 
     
     
       6. The window defined in  claim 2  wherein the first and second transparent conductive electrodes comprise a material selected from the group consisting of: indium tin oxide and conductive polymer. 
     
     
       7. The window defined in  claim 2  further comprising a first transparent substrate on which the first electrode is formed and a second transparent substrate on which the second electrode is formed. 
     
     
       8. The window defined in  claim 7  wherein the first and second transparent substrates comprise respective first and second polymer films. 
     
     
       9. The window defined in  claim 8  wherein the first and second transparent substrates have curved cross-sectional profiles. 
     
     
       10. The window defined in  claim 9  wherein the first and second structural window layers comprise first and second respective glass layers. 
     
     
       11. The window defined in  claim 2  wherein the adjustable transmission layer is configured to exhibit a clear state with a transmission of at least 30% when a first alternating current signal is applied across the first and second electrodes and is configured to exhibit a dark state with a transmission of less than 10% when a second alternating current signal is applied across the first and second electrodes. 
     
     
       12. The window defined in  claim 11  wherein the second voltage is less than the first voltage. 
     
     
       13. The window defined in  claim 1  wherein the first structural window layer comprises a laminated layer having a pair of glass layers with an interposed layer of polymer. 
     
     
       14. The window defined in  claim 1  wherein the guest-host liquid crystal nanosized cells droplets exhibit a clearing temperature of at least 100° C. 
     
     
       15. The window defined in  claim 1  wherein the guest dye molecules comprise dichroic dye and wherein the liquid crystal exhibits a birefringence of less than 0.08. 
     
     
       16. The window defined in  claim 1  wherein the guest dye molecules comprise dichroic dye, and wherein the adjustable transmission layer is configured to adjust in response to an alternating-current drive signal. 
     
     
       17. A system, comprising:
 a body structure; 
 a window mounted in the body structure that separates an interior region from an exterior region, wherein the window comprises an adjustable light transmission layer having opposing first and second conductive electrode layers and having a layer of polymer with embedded guest-host liquid crystal nanosized droplets between the first and second conductive electrode layers, and wherein each of the embedded guest-host liquid crystal nanosized droplets contains liquid crystal and guest dye molecules; 
 input-output circuitry configured to receive a command; and 
 control circuitry configured to adjust light transmission through the window by adjusting an alternating-current drive signal applied by the first and second conductive electrode layers to the layer of polymer with the embedded guest-host liquid crystal nanosized droplets. 
 
     
     
       18. The system defined in  claim 17  wherein the control circuitry is configured to adjust the window between a clear state in which the adjustable light transmission layer exhibits a transmission of at least 30% and a haze of less than 5% and a dark state in which the adjustable light transmission layer exhibits a transmission of less than 10%. 
     
     
       19. The system defined in  claim 18  wherein the control circuitry is configured to apply a first alternating-current signal in the clear state and a second alternating-current signal in the dark state and wherein the control circuitry is configured to change from the first alternating-current signal to the second alternating-current signal in a minimum of 10 ms. 
     
     
       20. A system, comprising:
 a support structure; 
 a glass layer with a curved cross-sectional profile in the support structure; and 
 an adjustable light transmission layer on the curved glass layer, wherein the adjustable light transmission layer comprises first and second transparent conductive electrode layers, a polymer matrix layer between the first and second transparent conductive electrode layers, and guest-host liquid crystal nanosized droplets embedded in the polymer matrix layer, wherein the guest-host liquid crystal nanosized droplets each comprise liquid crystal material and dichroic dye. 
 
     
     
       21. The system defined in  claim 20  further comprising:
 a first polymer film on which the first transparent conductive electrode layer is formed; and 
 a second polymer film on which the second transparent conductive electrode layer is formed. 
 
     
     
       22. The system defined in  claim 21  wherein the polymer matrix layer comprises a first polymer matrix sublayer, a second polymer matrix sublayer, and a layer of adhesive configured to bond the first and second polymer matrix sublayers.

Description:
This application claims the benefit of provisional patent application No. 63/061,058, filed Aug. 4, 2020, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to structures that pass light, and, more particularly, to windows. 
     BACKGROUND 
     Windows such as vehicle windows sometimes include glass layers. To enhance privacy or block sunlight, windows may sometimes be tinted. 
     SUMMARY 
     A system such as a vehicle, building, or electronic device system may have a support structure with one or more windows. The support structure and window may separate an interior region within the system from a surrounding exterior region. Control circuitry and input-output devices may be mounted within the support structure. 
     During operation, the control circuitry may use the input-output circuitry to receive input. The input may be, for example, user input such as input from a vehicle occupant. 
     Based on the input, the control circuitry may adjust an alternating-current drive signal or other control signal for an adjustable light transmission layer in the window. The adjustments to the drive signal may be used to adjust the amount of light transmission exhibited by the adjustable light transmission layer. The adjustable light transmission layer may be operated in a dark state to prevent light from passing through the window, a clear state in which the window passes light, and intermediate light transmission levels in which some light is passed and some light is blocked. 
     The adjustable light transmission layer may have a polymer matrix layer with embedded guest-host liquid crystal cells. Each cell may have liquid crystal material and dichroic dye. Transparent electrodes in the adjustable light transmission layer may be supported by respective transparent substrate layers. Structural glass layers or other window structures may be used to support the adjustable light transmission layer. If desired, the layers forming a window such as the structural glass layers and the layers forming the adjustable light transmission layer may have curved cross-sectional profiles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of an illustrative system in accordance with an embodiment. 
         FIGS.  2  and  3    are cross-sectional side views of an illustrative guest-host liquid crystal cell in an adjustable transmission window layer in accordance with an embodiment. 
         FIG.  4    is a cross-sectional side view of part of an illustrative adjustable transmission window layer in accordance with an embodiment. 
         FIG.  5    is a cross-sectional side view of an adjustable transmission window layer in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A system may have windows. The windows may include electrically adjustable components such as adjustable light transmission components, which may sometimes be referred to as adjustable transmission layers, adjustable tint layers, adjustable light-transmission window layers, adjustable light transmission layers, or adjustable light absorbers. Systems that that may be provided with windows having electrically adjustable light transmission layers may include buildings, vehicles, electronic devices systems (e.g., head-mounted devices such as glasses with adjustable transmission lenses), and other suitable systems. Illustrative configurations in which systems with adjustable light transmission windows are vehicles may sometimes be described herein as an example. This is merely illustrative. Adjustable transmission window structures may be formed in any suitable systems. 
     An electrically adjustable light transmission layer may be formed using a polymer layer (sometimes referred to as a matrix or polymer matrix) in which numerous cells of guest-host liquid crystal material have been dispersed. Each cell may include liquid crystal material and dichroic dye (e.g., anisotropic guest dye molecules). The dye molecules align with liquid crystals in the liquid crystal material. Transparent electrodes may be used to adjust the electric field through the polymer layer. This allows the alignment state of the liquid crystals and guest dye to be adjusted and therefore allows the light transmission of the adjustable light transmission layer to be adjusted. 
     An illustrative system of the type that may include adjustable light transmission windows is shown in  FIG.  1   . As shown in  FIG.  1   , system  10  may have a support structure such as support structure  12  that supports one or more windows such as window  16 . Support structure  12  and window  16  separate interior region  18  from exterior region  14 . During at least some operating modes, window  16  may be transparent to allow occupants of system  10  who are located within interior region  18  to view objects located in exterior region  14  through window  16 . 
     Structure  12  may form walls of a building, a vehicle body, an electronic device housing (e.g., a frame for a pair of glasses) or other supporting structures. In arrangements in which structure  12  forms a vehicle body, structure  12  may include a chassis to which wheels, propulsion systems, steering systems, and other vehicle systems are mounted and may include doors, trunk structures, a hood, side body panels, a roof, and/or other body structures. 
     System  10  may include control circuitry  20  and input-output devices  22 . Input-output devices  22  may include sensors (e.g., touch sensors, a microphone, buttons, etc.), audio components, displays, and other components for providing output to an occupant of system  10 , for making measurements of the environment surrounding vehicle  10 , and for gathering input from an occupant of system  10 . Control circuitry  20  may include storage and processing circuitry such as volatile and non-volatile memory, microprocessors, application-specific integrated circuits, digital signal processors, microcontroller, and other circuitry for controlling the operation of system  10 . In scenarios in which system  10  is a vehicle, control circuitry  20  may control the components of the vehicle based on user input and other input from input-output device  22  (e.g., to adjust the vehicle&#39;s steering, brakes, throttle, and other controls associated with driving the vehicle and/or to adjust window transparency for window  16  and/or other settings associated with operations other than driving the vehicle). If desired, system  10  may be an autonomously driven vehicle. Window settings such as window transparency may be adjusted using voice comments, button input, touch screen input on a control panel or a touch sensitive window area, and/or other input (e.g., vehicle occupant input). 
     As shown in  FIG.  1   , window  16  may include multiple window layers  16 L. Window layers  16 L may include layers of transparent material such as transparent layers of glass, transparent layers of polymer, transparent semiconductor layers (e.g., transparent indium tin oxide layers or other transparent conductive layers), transparent polymer layers, and/or other transparent layers. These layers may include rigid and/or flexible materials. In some configurations, layers  16 L and window  16  are flat. In other configurations, some or all of window  16  is curved. As an example, illustrative window  16 X of  FIG.  1    may have a curved cross-sectional profile and may optionally exhibit areas with compound curvature (e.g., areas where window  16 X has non-developable surfaces). Illustrative arrangements in which window  16  has a planar shape may sometimes be described herein as an example. 
     Window layers  16 L may include one or more adjustable light transmission layers. Layers  16 L may also include one or more structural layers. As an example, window layers  16 L may include multiple structural glass layers. In some configurations, these layers may include an inner transparent structural layer (sometimes referred to as an inner glass layer) and an outer transparent structural layer (sometimes referred to as an outer glass layer). Optional additional layers may be included. The inner and outer layers of the window and/or other layers  16 L may include adjacent layers that are separated by an air gap and/or may include adjacent layers that are spaced apart by a gap that is filled with polymer, liquid, other dielectric, layers forming an adjustable light transmission device, etc. As an example, layers  16 L may include an outer window layer, an inner window layer, and an adjustable light transmission layer sandwiched between the outer layer without air gaps. 
     Layers  16 L (e.g., inner and/or outer structural glass layers surrounding an adjustable light transmission layer) may include single-layer glass layers (e.g., single layers of tempered glass) or, in some configurations, may include multi-layer structures formed, for example, from first and second glass layers that are laminated together. A laminated glass layer may have a polymer such as polyvinyl butyral (PVB) or a layer of another polymer that joins first and second glass layers to form a sheet of laminated glass. Multi-layer glass structures (laminated glass layers formed from two or more laminated glass layers with interposed PVB) and single-layer glass layers may include optional tinting (e.g., dye, pigment, etc.). Polymer layers in laminated glass layers (e.g., PVB layers) may also optionally be tinted. 
     Adjustable light transmission may be provided using electrically adjustable guest-host liquid crystal material. To help avoid undesirable uniformity issues such as gravity-induced mura as well as undesired pressure sensitivity, the guest-host liquid crystal material may be formed in nanosized cells such as the illustrative cells of  FIGS.  2  and  3   . Guest-host cells  30  of  FIGS.  2  and  3    may be spheres that are formed within a polymer matrix. The spheres may be filled with liquid crystals  32  (the “host”) and anisotropic dye molecules  34  (the “guest”). 
     Cells  30  may have diameters of less than 200 nm, less than 150 nm, or other small size to help reduce light scattering. The liquid crystal material preferably exhibits a low birefringence (e.g., less than 0.12, less than 0.08, or other suitable value). The refractive index of the polymer matrix may be matched to that of cells  32  (e.g., the refractive index of the liquid crystal material in cells  30  when cells  30  are in their transparent state) to help avoid undesired haze when the adjustable layer is transparent (e.g., a haze of less than 5%). Index matching may be achieved by ensuring that the refractive indices of the polymer matrix and cells  30  (in the transparent cell state) differs by less than 0.15, less than 0.1, less than 0.05, less than 0.02, or other suitably low amount. 
     The clearing temperature of the liquid crystal material of cells  30  is preferably at least 100° C., which allows window  16  to be operated at relatively high temperatures (e.g., 60° C. or  70  ºC). Cells  30  may use either a nematic liquid crystal mode or a cholesteric liquid crystal mode. To help introduce helical twisting in the cholesteric liquid crystal mode, chiral dopant may be added to cells  30 . The presence of chiral dopant in cells  30  may help make cells  30  exhibit more uniform light absorption for different polarization states of transmitted light when using a cholesteric liquid crystal arrangement. 
     There is typically more liquid crystal material in cells  30  than dye material (e.g., the dye may make up about 2-3% of cells  30 ). The orientation of liquid crystals  32  can be adjusted by adjusting the electric field applied to liquid crystals  32 . The orientation of dye molecules  34  tracks that of liquid crystals  32 . The light transmission exhibited by cells  30  (and therefore the transmission of adjustable transmission layer  16 L formed from cells  30 ) is medium to high (e.g., at least 30%, at least 40% at least 50%, at least 60% at least 75%, at least 85%, at least 90%, etc.) when a control signal (e.g., an alternating-current drive signal VON) is applied so that liquid crystals  32  and dye molecules  34  are aligned in a first state (e.g., parallel to the direction of incoming light rays such as illustrative light ray  36  in the example of  FIG.  2   ) and this light transmission is low (e.g., less than 15%, less than 10%, less than 5%, 0%, etc.) when the control signal (e.g., an alternating-current drive signal VOFF) is applied so that liquid crystals  32  and dye molecules  34  are aligned in a second state (e.g., when liquid crystals  32  and dye molecules  34  are oriented randomly and are not aligned parallel to light ray  36 , as shown in the example of  FIG.  3   ). The medium to high transmission state, which may sometimes be referred to as a clear state, may be characterized by low haze (e.g., less than 5%). The low transmission state, which may sometimes be referred to as a dark state, may be used to block exterior sunlight and to provide vehicle occupants with privacy by blocking interior region  18  from view from exterior region  14 . 
     Any suitable drive signal may be used in adjusting the transmission of cells  30 . In an illustrative configuration, alternating-current (AC) drive signals are used (e.g., square wave signals or other AC signals). The frequency of the AC drive signals may be at least 1 Hz, at least 10 Hz, at least 40 Hz, less than 480 Hz, less than 100 Hz, 10-100 Hz, or other suitable frequency. The peak-to-peak voltage of the drive signal (e.g., the voltage applied from one surface of the adjustable transmission layer to the other by a pair of transparent electrodes) may be at least 10 V, at least 20 V, less than 60 V, less than 40 V, 10-60 V, etc. (e.g., when placing cells  30  in a clear state). The peak-to-peak voltage may be different (e.g., 0V, less than 1 V, less than 0.5 V, etc.) when operating cells  30  in an opaque (dark) mode. The drive signal can be adjusted by control circuitry  20  based on user input (e.g., user input directing control circuitry  20  to make window  16  opaque, clear, or to exhibit an intermediate level of light transmission). If desired, the drive voltage can be ramped up or down no faster than a minimum predetermined ramp time. This minimum time period for changing the drive voltage between its clear mode and dark mode states may have, for example, a value of 10 ms, a value of 10 ms to 100 ms, or other suitable value to help avoid transient haze issues that are associated with the amount of time required for helical liquid crystal structures in cells  30  to unwind or reform when changing their alignment. 
     An adjustable light transmission layer may be formed by creating a layer of polymer matrix material that includes embedded guest-host liquid crystal cells  30  sandwiched between a pair of opposing conductive electrodes. Optional substrate layers may be used to help support the polymer matrix layer (e.g., during manufacturing). In an illustrative arrangement, guest-host liquid crystal material with surfactant is dispersed into a liquid polymer matrix solution (liquid polymer precursor material for the polymer matrix). High pressure and/or vibration then may be used to break the guest-host liquid crystal material into nanodroplets forming cells  30 . After cells  30  have been embedded throughout the matrix in this way, the liquid polymer of the matrix may be cured (e.g., by application of light such as ultraviolet light and/or high temperature), followed by baking to harden the matrix layer. 
     If desired, a pair of substrates each of which has been coated with a polymer matrix with embedded guest-host liquid crystal cells  30  may be sandwiched together to form an adjustable light transmission layer. Consider, as an example, the scenarios illustrated in  FIGS.  4    and  5 . 
     Initially, as shown in  FIG.  4   , substrate layer  38  may be covered with a transparent conductive electrode layer such as electrode  40 . Substrate layer  38  may be formed from a rigid or flexible polymer film (e.g., a polyethylene terephthalate, cyclic olefin polymer, cellulose triacetate, polycarbonate, or other polymer materials). These materials and/or other polymers may also be used in forming polymer matrix  50 . The thickness of substrate layer  38  may be, as an example, at least 1 micron, at least 10 microns, at least 100 microns, less than 3 mm, less than 500 microns, less than 150 microns, less than 30 microns, or other suitable thickness. Electrode  40  may be formed from a transparent conductive layer such as a layer of indium tin oxide, a transparent conductive polymer such as poly(3,4-ethylenedioxythiophene) (PEDOT), or other transparent conductive layer. The thickness of electrode  40  may be, for example, at least 0.1 micron, at least 1 micron, at least 10 microns, less than 100 microns, less than 20 microns, less than 2 microns, or other suitable thickness. 
     Polymer matrix  50  and embedded guest-host liquid crystal cells  30  may be formed by depositing liquid polymer precursor material for matrix  50  that contains guest-host liquid crystal material onto electrode  40  followed by application of pressure and/or vibrations to form cells  30 . The thickness of the layer of matrix  50  that is formed on electrode  40  may be 4-10 microns (e.g., about 6 microns), at least 1 micron, at least 2 microns, at least 4 microns, less than 30 microns, less than 15 microns, less than 9 microns, or other suitable thickness). 
     After curing matrix  50  and thereby forming partial layer  16 L′ of  FIG.  4   , a pair of these layers (with layers of matrix  50  facing each other) may be attached to each other along bond line  42  to form an adjusted transmission window layer  16 L of the type shown in  FIG.  5   . The thickness of the layer of matrix  50  that is formed by joining the two matrix layers of  FIG.  5    along bond line  42  may be 8-20 microns, about 12 microns, at least 3 microns, at least 5 microns, at least 10 microns, less than 30 microns, less than 20 microns, less than 10 microns, or other suitable thickness. 
     Bonding along bond line  42  may be performed by pressing upper and lower layers of polymer matrix  50  together under heat and/or pressure and or may involve attaching these layers of polymer matrix  50  using an optional interposed layer adhesive (e.g., a layer of clear liquid adhesive may be used to bond layers  16 L′ along bond line  42  of  FIG.  5   ). As shown in  FIG.  5   , edge portion  16 C of layer  16 L may have a protruding portion of substrate  38  and an associated electrode  40  to provide a contact (e.g., adjustable layer terminal). This contact may be coupled to a signal line such as signal line  44  (e.g. a wire, a metal foil, a printed circuit with metal traces, etc.) using conductive material  46  (e.g., solder, conductive adhesive, etc.). 
     Following formation of window  16 , window  16  may be installed in a window opening in support structure  12  or other portion of system  10 . 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20210630
Publication Date: 20240917
Grant Date: 20240917
Priority Date: 20200804
Inventors: CHEN, YUAN
YANG, Falu
XIANYU, HAIQING
Masschelein, Peter F.
CHOI, SANG UN
LI, XIAOKAI
LEE, YUNSEOK
GE, ZHIBING
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/13725", "inventive": true, "first": false, "tree": "[]"}, {"code": "E06B9/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1334", "inventive": true, "first": false, "tree": "[]"}, {"code": "E06B2009/2464", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60J3/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133711", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/133711", "inventive": true, "first": false, "tree": "[]"}, {"code": "E06B9/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "E06B2009/2464", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1334", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60J3/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "E06B2009/2464", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133711", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1334", "inventive": true, "first": false, "tree": "[]"}, {"code": "E06B9/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60J3/04", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 92716114