PATENT DOCUMENT

Publication Number: US-10488686-B1
Application Number: US-201715634946-A
Country: US
Kind Code: B1

Title: Systems with synchronized windows

Abstract:
A system such as a vehicle may have window that exhibit adjustable transparency. The windows may include liquid crystal devices and polymer dispersed liquid crystal devices that exhibit adjustable amounts of light transmission and haze. An optical property of a window such as window transparency may be modulated using an alternating-current modulation waveform. Modulation of the transparency of the window may be synchronized with modulated light output from a light source. The light source may be located inside the vehicle or may be located outside of the vehicle. By synchronizing the modulation of the transparency of the window with the light source output, privacy may be enhanced or glare may be reduced.

Claims:
What is claimed is: 
     
       1. A vehicle, comprising:
 a body having an interior; 
 control circuitry; 
 an adjustable window in the body that is between the interior and an exterior region surrounding the body, wherein the adjustable window has an optical property that is modulated by the control circuitry; and 
 a light source that produces output light that is modulated by the control circuitry in synchronization with the modulation of the optical property of the adjustable window, wherein the light source comprises an internal light that emits the output light and wherein the output light at least partially illuminates the interior. 
 
     
     
       2. The vehicle defined in  claim 1  wherein the adjustable window comprises a light modulator layer and wherein the optical property comprises a light transmittance of the adjustable window that the control circuitry modulates using the light modulator layer. 
     
     
       3. The vehicle defined in  claim 2  wherein the control circuitry is configured to modulate the light transmittance of the light modulator layer in accordance with an alternating-current light transmittance modulation waveform and is configured to modulate the output light with a synchronized alternating-current light output modulation waveform. 
     
     
       4. The vehicle defined in  claim 3  wherein the light modulator layer comprises a light modulator layer selected from the group consisting of: a liquid crystal light modulator with polarizers, a guest-host liquid crystal light modulator layer, and a cholesteric liquid crystal light modulator layer. 
     
     
       5. The vehicle defined in  claim 3  wherein the alternating-current light transmittance modulation waveform has a frequency of at least 60 Hz. 
     
     
       6. The vehicle defined in  claim 1  wherein the internal light includes at least one light-emitting diode that emits the output light. 
     
     
       7. The vehicle defined in  claim 1  wherein the internal light forms part of a display having a pixel array that displays images. 
     
     
       8. The vehicle defined in  claim 7  wherein the display has a backlight unit with at least one light-emitting diode that produces the output light. 
     
     
       9. The vehicle defined in  claim 3  wherein the light source comprises an image projector. 
     
     
       10. The vehicle defined in  claim 1  wherein the adjustable window comprises an adjustable reflectivity layer, wherein the optical property is a reflectivity of the adjustable window that is modulated by the control circuitry, and wherein the adjustable reflectivity layer comprises a cholesteric liquid crystal layer. 
     
     
       11. The vehicle defined in  claim 1  wherein the adjustable window comprises an adjustable haze layer and wherein the optical property is a haze of the adjustable window that is modulated by the control circuitry. 
     
     
       12. The vehicle defined in  claim 11  wherein the adjustable haze layer comprises a polymer dispersed liquid crystal layer. 
     
     
       13. A vehicle, comprising:
 a body having an interior; 
 control circuitry; 
 an adjustable window in the body that is between the interior and an exterior region surrounding the body, wherein the adjustable window has an optical property that is modulated by the control circuitry; and 
 a light source that produces output light that is modulated by the control circuitry in synchronization with the modulation of the optical property of the adjustable window, wherein the optical property that is modulated comprises a window transparency for the adjustable window, wherein the window transparency is reduced when the output light is increased, and wherein the window transparency is increased when the output light is decreased. 
 
     
     
       14. A vehicle, comprising:
 a body having an interior; 
 control circuitry; 
 an adjustable window in the body that is between the interior and an exterior region surrounding the body, wherein the adjustable window has an optical property that is modulated by the control circuitry; and 
 a light source that produces output light that is modulated by the control circuitry in synchronization with the modulation of the optical property of the adjustable window, wherein the light source comprises an exterior light source and the output light comprises external light supplied by the exterior light source. 
 
     
     
       15. The vehicle defined in  claim 14 , wherein the optical property that is modulated comprises a window transparency for the adjustable window, and wherein the window transparency is modulated by a first alternating current modulation waveform and alternates between a first transparency and a second transparency that is greater than the first transparency. 
     
     
       16. The vehicle defined in  claim 15 , wherein the external light is modulated by a second alternating current modulation waveform that is synchronized with the first alternating current modulation waveform, wherein the external light alternates between a first intensity when the adjustable window has the first transparency and a second intensity that is less than the first intensity when the adjustable window has the second transparency, further comprising a light sensor, wherein the control circuitry synchronizes the first alternating current modulation waveform and the second alternating current modulation waveform using information on the external light measured with the light sensor. 
     
     
       17. A vehicle, comprising:
 a body having an interior; 
 control circuitry; 
 an adjustable window in the body that is between the interior and an exterior region surrounding the body, wherein the adjustable window has an optical property that is modulated by the control circuitry; and 
 a light source that produces output light that is modulated by the control circuitry in synchronization with the modulation of the optical property of the adjustable window, wherein the optical property that is modulated comprises a window transparency for the adjustable window, wherein the window transparency is modulated by an alternating current modulation waveform and alternates between a first transparency and a second transparency that is greater than the first transparency. 
 
     
     
       18. The vehicle defined in  claim 17  wherein the adjustable window comprises an adjustable reflectivity layer, wherein the optical property is a reflectivity of the adjustable window that is modulated by the control circuitry, and wherein the adjustable reflectivity layer comprises a cholesteric liquid crystal layer. 
     
     
       19. The vehicle defined in  claim 17  wherein the adjustable window comprises an adjustable haze layer and wherein the optical property is a haze of the adjustable window that is modulated by the control circuitry. 
     
     
       20. The vehicle defined in  claim 13  wherein the adjustable window comprises an adjustable reflectivity layer, wherein the optical property is a reflectivity of the adjustable window that is modulated by the control circuitry, and wherein the adjustable reflectivity layer comprises a cholesteric liquid crystal layer.

Description:
This application claims the benefit of provisional patent application No. 62/368,108, filed on Jul. 28, 2016, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to structures that pass light, and, more particularly, to synchronizing adjustable windows such as vehicle windows with equipment that produces light. 
     BACKGROUND 
     Vehicle occupants often desire privacy. Privacy sunshades may be raised to cover windows to provide privacy, but can block an occupant&#39;s view out of the windows. One-way mirror coatings or tints can be formed on the side windows of a vehicle to enhance privacy, but these arrangements may cause the windows to be too shiny or too dark. 
     It can therefore be challenging to provide vehicle windows with desired characteristics. If care is not taken, windows may be too reflective, may be insufficiently transparent for viewing, may have an appearance that is insufficiently flexible, or may have other undesired attributes. 
     SUMMARY 
     A system such as a vehicle may have windows with adjustable optical properties. A window may include a light modulator layer such as a liquid crystal layer with polarizers, may include a guest-host liquid crystal light modulator layer, may include a cholesteric liquid crystal layer that can be adjusted to exhibit changes in light transmission and reflectivity, may include an adjustable haze layer such as polymer dispersed liquid crystal layer, and may include other layers that can be controlled to adjust the transparency of the window (e.g., to exhibit adjustable amounts of light transmission and/or haze). 
     A vehicle window may interact with internal and external source of light. A vehicle may, for example, include an interior light that illuminates interior objects in the vehicle. A vehicle may also include a display with an array of pixels for displaying images. A display may be hardwired into a vehicle. Displays associated with portable electronic devices may also be placed in the interior of a vehicle. Another source of light that may be used in a vehicle interior is an image projector that projects image onto a screen or a portion of a vehicle window. External light sources that produce light in the vicinity of a vehicle include a vehicle&#39;s headlights or tail lights, headlights on other vehicles, street lights, and other exterior lighting. 
     Internal and external sources of light may be modulated with alternating current modulation waveforms. For example, an interior light may be turned on and off in accordance with an alternating current modulation waveform. The frequency with which the interior light is turned on and off may be sufficiently high to make the modulation of the interior light undetectable to a vehicle occupant. For example, the interior light may be turned on and off at a frequency of 200 Hz, which is too rapid to be noticed by the human eye. Accordingly, the modulation of the light produced by the interior light may be unnoticeable to a vehicle user. If desired, display output, projector output, exterior lighting output, and/or other light output may be modulated with the alternating current modulation waveform. 
     The adjustable optical properties of the window (e.g., light transmission, haze, and reflectivity) may be modulated using an alternating current modulation waveform that is synchronized to the modulation waveform that is used in producing the light from an internal and/or external source of light. This may help enhance privacy or reduce glare by ensuring that the window has a reduced transparency whenever the source of light is emitting light. At the same time, the window is still partially transparent, because the window is dark only during portions of the alternating current modulation waveform. 
     Light source modulation and window modulation control signals can be synchronized by coupling control circuitry in a vehicle directly to a light source and to a light modulator in a window using hardwired paths. The hardwired paths may be used in conveying modulation signals to the light source and light modulator from the control circuitry. Synchronization operations may also be performed by providing the control circuitry with information on the output of the modulated light source using a light detector or by wirelessly conveying synchronization information from a modulated light source to the control circuitry. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative system in accordance with an embodiment. 
         FIG. 2  is a diagram of the illustrative system of  FIG. 1  showing components that may be placed in interior and exterior locations in accordance with an embodiment. 
         FIG. 3  is a diagram of illustrative components in a system with a window in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of an illustrative display having a backlight with a light source that may be modulated in accordance with an embodiment. 
         FIG. 5  is a graph showing how modulated light output from an interior light or interior display may be synchronized with a modulated window transparency in accordance with an embodiment. 
         FIG. 6  is a graph showing how modulated exterior light from an exterior lighting source may be synchronized with window transparency modulation in accordance with an embodiment. 
         FIG. 7  is a graph showing how the modulated output of a projector in a vehicle interior may be synchronized with window transparency modulation in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A system may have windows formed from electrically adjustable components. The system may be a building, a vehicle, or other suitable system. Illustrative configurations in which the system with the windows is a vehicle may sometimes be described herein as an example. This is merely illustrative. Window structures may be formed in any suitable system. 
     The electrically adjustable components of the windows may be used to adjust the optical properties of the windows. For example, electrically adjustable windows may be adjusted to change the reflectivity and therefore the light transmission of the windows, may be used to adjust the absorption of light by the windows and therefore the transmission (transmissivity) of the windows to light, and/or may adjusted to change the haze of the windows as a function of time. If desired, modulation of the optical properties of the windows may be made in synchronization with modulation of the light output from interior lights, light emitted by the pixels in a display pixel array, a projector, and/or exterior lights. 
     The transparency of a window may, as an example, be modulated using an alternating-current transparency modulation waveform such as a square wave or other modulation signal. A light-emitting component such as an interior light may be modulated in synchronization with the window transparency modulation signal using the same alternating-current waveform. When synchronized in this way, the window may be opaque or hazy each time the interior light is turned on and may be transparent each time the interior light is turned off. 
     The frequency of the alternating-current modulation signal may relatively high (e.g., over 60 Hz, over 100 Hz, 200 Hz or more, or other suitable frequency). These frequencies create light intensity changes that are more rapid than can be detected by the eyes of a human observer. As a result, the alternating-current interior light appears constant to an occupant of the vehicle and the windows appear to have a constant transparency level (no flicker). At the same time, when the exterior of the vehicle is dark (e.g., at night), external observers of the vehicle will not be able to see inside the vehicle because the window is non-transparent whenever the interior light producing component is producing light. 
     An illustrative system with windows is shown in  FIG. 1 . As shown in  FIG. 1 , system  10  may be a vehicle having a body such as body  12  with a chassis to which wheels are mounted, propulsion and steering systems, and other vehicle systems. Body  12  may include doors, trunk structures, a hood, side body panels, a roof, and/or other body structures. Seats may be formed in the interior of vehicle  10 . Vehicle  10  may include windows such as window(s)  16 . Window  16  and portions of body  12  may separate the interior of vehicle  10  from the exterior environment that is surrounding vehicle  10 . 
     Windows  16  may include a front window  16  on front F of vehicle  10 , a moon roof window  16  or other window extending over some or all of top T of vehicle  10 , a rear window  16  on rear R of vehicle  10 , and side windows on the sides of vehicle  10  between front F and rear R. Window  16  may be formed from one or more layers of transparent glass, clear polymer (e.g., polycarbonate), polymer adhesive layers, and/or other layers. In some arrangements, window(s)  16  may include laminated window structures such as one or more layers of glass with interposed polymer layer(s). The polymer in a laminated window may be, for example, a polymer such as polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA). Adjustable layers in window  16  may, if desired, be embedded in a polymer layer such as a PVB or EVA layer that is interposed between outer and inner glass layers. If desired, exterior lights  26  and other components in vehicles such as vehicle  10  may be provided with adjustable layers (e.g., electrically adjustable components to adjust reflection, light transmission, haze, and/or other optical properties for lights  26 ). 
     Vehicle  10  may include control circuitry  24  and input-output devices  22 . Control circuitry  24  may include storage and processing circuitry for supporting the operation of vehicle  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  24  may be used to control the operation of vehicle  10  and the components in vehicle  10  (e.g., components associated with windows  16 , lights  26 , input-output components  22 , etc.). For example, processing circuitry can adjust the haze, light transmission, and/or reflectivity of one or more layers in windows  16 , may make adjustments to other input-output components  22 , and/or may make other adjustments to components such as windows  16 , lights  26 , etc. The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Input-output devices  22  may be used to gather data for vehicle  10 , may be used to gather information from a user (vehicle occupant, etc.) of vehicle  10 , may be used to provide data from vehicle  10  to external systems or a user, and/or may be used in handling other input and output operations. Input-output devices  22  may include buttons, scrolling wheels, touch pads, key pads, keyboards, and other user input devices. Microphones may be used to gather voice input from a user and may gather information on ambient sounds. Devices  22  may include ambient light sensors, proximity sensors, magnetic sensors, force sensors, accelerometers, image sensors, and/or other sensors for gathering input. Output may be supplied by devices  22  using audio speakers, tone generators, vibrators, haptic devices, displays, light-emitting diodes and other light sources, and other output components. Vehicle  10  (e.g., devices  22 , etc.) may include wired and wireless communications circuitry that allows vehicle  10  (e.g., control circuitry  24 ) to communicate with external equipment and that allows signals to be conveyed between components (circuitry) at different locations in vehicle  10 . 
     A diagram of vehicle  10  that shows vehicle  10  in an illustrative operating environment is shown in  FIG. 2 . Vehicle  10  may have a body such as body  12  that defines an interior region such as interior  30  and an exterior region such as region  32 . Window  16  may be mounted in body  12  of vehicle  10  and may separate interior  30  from exterior  32 . Window  16  may have one or more layers with optical properties (e.g., light transmission, reflectivity, and/or haze) that can be electrically adjusted by control circuitry  24 . Window  16  may also have structural glass layers that help support the layer(s) with adjustable optical properties. For example, window  16  may have an outer glass layer and an inner glass layer that are laminated to each other with a PVB layer, an EVA layer, or other adhesive layer. One or more adjustable components (light modulators, adjustable haze layers, adjustable reflectors, etc.) may be incorporated into window  16  (e.g., by embedding one or more of these adjustable components in the adhesive layer between the outer and inner glass layers. 
     Adjustable components that may be used in adjusting light transmission for window  16  include liquid crystal light modulators (e.g., liquid crystal light modulator layers with polarizers such as liquid crystal light modulator layers having liquid crystal material and electrodes for applying electric fields to the liquid crystal material that are interposed between a pair of polarizers) and guest-host liquid crystal light modulators. A guest-host liquid crystal device may include a light-absorbing dye “guest” in a liquid crystal “host” layer. These materials may form a layer that is sandwiched between a pair of transparent electrodes. When an electric field is applied to the guest-host layer, the liquid crystals rotate, thereby rotating the guest dye into an orientation that enhances light absorption. When the electric field is removed, the guest dye molecules are no longer held in the high-absorption orientation so that the light modulator layer becomes transparent. If desired, the electric field strength may be adjusted to produce an intermediate level of light absorption. 
     Adjustable components that may be used in adjusting reflectivity for window  16  and therefore in adjusting light transmission for window  16  include cholesteric liquid crystal layers. Cholesteric liquid crystal layers may exhibit relatively fast switching speeds, low haze (e.g., haze values of less than 5%), and good reflectivity. A cholesteric liquid crystal device may exhibit a mirror reflectivity that is adjustable by adjusting a voltage applied to electrodes in the device. When used in window  16 , the cholesteric liquid crystal device may be characterized by an “on” state and an “off” state. In the “on” state (e.g., when control circuitry  24  applies a voltage to the device), the cholesteric liquid crystal device may be transparent. In the “off” state, the cholesteric liquid crystal device may act as a partial mirror and may reflect more than 50% of incident light, more than 70% of incident light, less than 99% of incident light, or other suitable amount of incident light. When in the off state, the device may be characterized by a reduced light transmission (i.e., the device may be light absorbing rather than transparent). Intermediate levels of light reflection may be achieved by applying an electric field across the cholesteric liquid crystal device at an intermediate level. Because light transmission can be modulated using an adjustable reflectivity layer such as a cholesteric liquid crystal layer, cholesteric liquid crystal devices may sometimes be referred to as light modulators, light modulation layers, and or light transmission modulators. 
     An adjustable component that may be used in adjusting haze (translucency) for window  16  (i.e., an adjustable haze layer) is a polymer-dispersed liquid crystal device. In this type of device, a polymer layer having voids filled with liquid crystal material may be sandwiched between conductive transparent electrodes on respective first and second transparent substrates. When no electric field is applied to the electrodes, the liquid crystals in the voids are randomly oriented and exhibit an index-of-refraction difference with the surrounding polymer layer. This causes the liquid crystal material of the voids to produce a relatively large amount of haze that scatters light that is passing through the device. When electric field is applied to the electrodes by control circuitry  24 , the liquid crystals in the voids becomes aligned so that the liquid crystal material in the voids exhibits an index of refraction that matches the surrounding polymer. In this configuration, the polymer-dispersed liquid crystal device exhibits low haze and high transparency. Intermediate haze levels may be achieved by applying an electric field at an intermediate level. 
     An adjustable light absorption layer such as a liquid crystal modulator or guest-host liquid crystal, an adjustable reflectivity layer such as a cholesteric liquid crystal layer or switchable metal hydride film, and/or an adjustable haze layer such as a polymer dispersed liquid crystal layer may be embedded within a PVB layer or other adhesive layer that is sandwiched between a pair of laminated glass layers (e.g., glass window layers that are being joined by the PVB layer to form a laminated window). Moreover, other types of light modulators, reflectivity modulators, and/or haze modulators may be used, if desired. 
     As shown in  FIG. 2 , system  10  may have an interior light source such as interior light source  34 . Light source  34  may be formed form one or more light-emitting diodes (e.g., red, green, and/or blue light-emitting diodes, white light-emitting diodes, etc.) or other source of illumination. Light source  34 , which may sometimes be referred to as an interior light source or interior light, may be located in interior  30  and may be used to illuminate interior objects in interior  30  such as object  38 . This allows a vehicle occupant such as occupant  44  to view interior objects such as object  38  even when it is dark outside of vehicle  10  and only small amounts of exterior light  50  from exterior light sources such as exterior light source  48  are entering interior  30 . 
     In addition to interior lighting from light source  34 , light may be emitted in interior  30  by components such as display  40  and image projector  54 . Display  40  may be, for example, a backlit liquid crystal display that has an array of pixels that emit light  42  (e.g., to display images for a user of vehicle  10  such as occupant  44 ). Projector  54  may emit light  56  for displaying images on a projector screen in interior  30 . Configurations in which projector  54  emits light  56  for displaying images on window  16  (e.g., by adjusting window  16  to be hazy and/or opaque at appropriate times) may also be used. 
     During the day, the ambient light levels outside of vehicle  10  in region  32  may be relatively large. This may lead to light reflections from the exterior of window  16  that help to obscure interior  30  from view by exterior observers such as observer  46 . Privacy may be enhanced by providing window  16  with a fixed and/or adjustable reflectivity, by incorporating a fixed and/or adjustable light absorbing layer into window  16 , and/or by incorporating a fixed and/or adjustable haze layer into window  16 . To ensure that window  16  is as transparent as possible while privacy is preserved (e.g., to allow occupant  44  to observe external objects such as object  52  in exterior region  32  through window  16 ), it may be desirable to modulate the optical properties of window  16 . For example, window  16  may be opaque whenever interior light from one or more interior light sources such as interior light  34 , display  40 , and/or projector  54  is present and may be transparent whenever interior light is at a low level or is completely absent. 
     With one suitable arrangement, window  16  is modulated with an alternating current modulation waveform and alternates between a first state in which window  16  has a first transmittance (e.g., a transmittance of 100%, a transmittance of more than 70%, a transmittance of 80-100%, etc.) and a second state in which window  16  has a second transmittance that is less than the first transmittance (e.g., a transmittance of 0-20%, a transmittance of less than 30%, etc. To prevent noticeable flickering in the appearance of window  16 , the state of window  16  may be modulated at a rate that is greater than the human eye&#39;s ability to perceive varying light intensities (e.g., using an alternating current modulation waveform with a frequency of 60 Hz or more, 100 Hz or more, 200 Hz or more, etc.). 
     In dim lighting conditions, there is usually little risk that external observers such as external observer  46  will be able to view light from exterior region  32  that has penetrated window  16  to illuminate interior  30 . There is, however, a significant risk that interior lighting (e.g., lighting from interior  30  such as interior light  36 , display light  42 , and projector light  56 ) may be visible to an external observer and may therefore compromise the privacy of occupant  44 . To prevent light  36 , light  42 , and/or light  56  from exiting interior  30  for viewing by observer  46 , light  36 ,  42 , and/or  56  may be modulated in synchronization with the modulation of window  16  so that light  36 ,  42 , and/or  56  is only present (or only has a high intensity) when window  16  is in a reduced transparency state such as the second state. 
     Privacy may therefore be enhanced by modulating light  36 ,  42 , and/or  56  in synchronization with the alternating current modulation waveform used in controlling the transmittance of window  16 , light  36 ,  42 , and/or  56  may be turned off (and/or may have a minimized intensity value) when window  16  is in its first (higher transmittance) state and may be turned on (and/or may have a maximized intensity value) on when window  16  is in its second (lower transmittance) state. By turning light  36  off except when window  16  is in a low transmittance state, interior objects such as object  38  that are illuminated by light  36  will not be visible from exterior region  32 . By turning off light  42  except when window  16  is in a low transmittance state, content on display  40  will be blocked from view by external observer  46 . Turning off projector light  56  that is projected in interior  30  except when window  16  is in a low transmittance state may also prevent light  56  from being viewed by external observer  46 . Light  36 , light  42 , and/or light  56  may be modulated in synchronization (so that two or more of these sources may be in synchronization with window  16 ) or only one of these light sources may be active and modulated in synchronization with window  16 . 
     If desired, the light produced by components that are outside of vehicle  10  may also be modulated in synchronization with windows  16 . For example, headlights, tail lights, and/or other exterior lights  26  on vehicle  10 , exterior lighting associated with other vehicles, street lights, and/or other light produced by external light sources, may be modulated so that this light is only produced when windows  16  are in a low transmittance state. This may help reduce glare in interior  30 . 
     To synchronize light producing components with windows  16 , system  10  may actively monitor light sources for the presence of emitted light (e.g., using ambient light sensors). Light sensor information may then be used by control circuitry  24  in synchronizing windows  16  with the light producing components. If desired, wireless synchronization messages and/or other wirelessly transmitted synchronization information may be exchanged between vehicle  10  and other light producing devices to help synchronize light producing devices with windows  16 . In arrangements in which control circuitry  24  can communicate with light producing components using hardwired paths, control circuitry  24  can synchronize the light producing components with windows  16  by supplying both the producing components and windows  16  with respective synchronized control signals over the hardwired paths. 
       FIG. 3  is a system diagram showing components and communications paths that may be used in ensuring synchronization between light producing components and windows  16 . As shown in  FIG. 3 , input-output components  22  may include light-emitting components such as light  58  (e.g., interior light  34  or exterior light  26 ) and projector  54 . 
     Display  40  in interior  30  may be a display this is mounted into a headrest, dashboard, door panel, seat, headliner, and/or other portion of vehicle  10 . In some situations, the display in interior  30  (display  40 ) may be a display associated with a portable electronic device that has been placed in interior (see, e.g., display  40 ′ of portable electronic device  62 ). Device  62  may be, for example, a cellular telephone, laptop computer, tablet computer, watch, or other portable electronic device belonging to occupant  44  of vehicle  10 . Device  62  may have a display (display  40 ′) that emits light  42 . 
     Another source of light involves external electronic equipment such as external system  78 . Systems such as system  78  are located in exterior region  32  and may include vehicles, buildings, roadside signs, and/or other external equipment. Equipment  78  may include a light-emitting component such as light  76  (e.g., a vehicle headlight or tail light or other exterior light, a street lamp, building lighting, lighting on a sign, etc.). 
     Light sources such as display  40  in a dashboard or other built-in display in vehicle  10 , projector  54 , and interior light  58  may be hardwired to control circuitry  24  and may therefore be modulated by control circuitry  24  in synchronization with the modulation of windows  16  that is controlled by control circuitry  24  (e.g., over a hardwired path). Other equipment such as electronic device  62  and external system  78  may produce light without direct hardwired control from control circuitry  24 . 
     One way of ensuring that the light produced by display  40 ′ and by light  76  is synchronized with window  16  is for control circuitry  24  to use light sensor  60  to capture information on emitted light  42  from display  40 ′ and emitted light  74  from light  76 . Display  40 ′ and system  78  may emit light that is modulated at a predetermined known frequency (e.g., 200 Hz). Based on light measurements from sensor  60 , control circuitry  24  can make phase and/or frequency adjustments to the modulation of window  16  to ensure that the modulation of window  16  is synchronous with the modulation of light  40 ′ and  76 . Schemes in which device  62  and/or system  78  use light sensors to synchronize to window  16  may also be used. 
     Another way of ensuring that the modulation of window  16  is synchronized with the modulation of light  42  and light  74  is to rely on wireless communications between vehicle  10  and device  62  and system  78 . Vehicle  10  may, for example, include wireless communications circuitry  70 . Wireless communications circuitry  70  may include an antenna and wireless transceiver circuitry configured to communicate wirelessly with corresponding antennas and wireless transceiver circuits in device  62  and system  78  over respective wireless links  68  and  72 . By exchanging wireless synchronization messages or other information, vehicle  10  and other equipment such as device  62  and system  78  can agree to modulate windows  16  and light producing components such as display  40 ′ and light  76  in synchronization with each other. 
     To modulate light  42  from display  40  (and display  40 ′), it may be desirable to provide display  40  (and  40 ′) with a configuration of the type shown in  FIG. 4 . In the example of  FIG. 4 , display  40  has an array of pixels P such as pixel array  82 . Pixel array  82  may be, for example, a liquid crystal display. Backlight unit  90  may produce backlight illumination (e.g., emitted light  42 ) that passes through pixel array  82  to present images to a viewer such as viewer  84  who is viewing display  40  in direction  86 . Backlight unit (backlight)  90  may have a light source such as light source  96 . Light source  96  may include an array of light-emitting diodes that emit light  98  into edge  100  of light guide layer  92 . Light  98  may propagate laterally in light guide layer  92  due to the principal of total internal reflection. Light extraction features on layer  92  may help direct some of light  98  out of layer  92  and upwards through pixel array  82  as light  42 . Reflector  94  may help reflect light that has been extracted downwardly back in the upwards direction through pixel array  82 . The overall intensity of light  42  may be modulated at 200 Hz or using an alternating current modulation waveform with another suitable alternating current frequency. For example, control circuitry  24  may supply a 200 Hz square wave drive current to light source  96  (as an example). 
     The graph of  FIG. 5  illustrates how the intensity of interior light  36 , light  42 , and/or light  56  may be modulated as a function of time. Curve  102  of  FIG. 5  represents an illustrative alternating current light output modulation waveform that may be used in modulating output light intensity. The graph of  FIG. 5  also shows how the optical properties of window  16  may be modulated as a function of time using the illustrative alternating current modulation waveform of curve  104 . The modulation waveforms represented by curves  102  and  104  are synchronized. During time periods when curve  102  is high, the intensity of light  36 , light  42 , and/or light  56  is high (maximized). During time periods when curve  102  is low, the intensity of light  36 , light  42 , and/or light  56  is correspondingly low (e.g., light intensity is minimized by turning the emitted light off or by at least reducing emitted light intensity during these low periods). Curve  104  may be complementary to curve  102  or may otherwise be synchronized with curve  102  to ensure that window transparency is reduced (i.e., light transmittance is reduced and/or haze is increased) whenever the emitted light of curve  102  is high and to ensure that window transparency is enhanced (i.e., light transmittance is increased and/or haze is reduced) whenever light intensity  102  is at its lower level. If desired, the pulses of emitted light from the modulated light source(s) may be shorter than the pulses of window modulation curve  104  (see, e.g., pulse  102 ′). It is also possible to somewhat misalign the modulation waveforms of curves  102  and  104  (e.g., so that the pulses in these signals are not perfectly complementary, but rather are shifted slightly with respect to each other), although doing so will reduce the light blocking ability of windows  16 . Light intensity and window transparency are modulated using square wave modulation waveforms in the example of  FIG. 5 , but can be modulated using other suitable alternating-current waveforms (e.g., sinusoidal, triangular, etc.) if desired. 
       FIG. 6  is a graph showing how exterior light intensity (curve  106 ) can be synchronized with windows  16 . Light intensity curve  106  represents the light intensity of light emitted from an external device such as light  74  from light  76  of  FIG. 3 . Light  74  is emitted from a location outside of interior  30  and may therefore represent an undesired source of glare for occupant  44 . To reduce the transmission of undesired exterior lighting into interior  30  and thereby reduce glare, window transparency may be decreased (e.g., by decreasing light transmittance and/or increasing haze for window  16 ) whenever light intensity  106  is high, as illustrated by illustrative window transparency modulation waveform (e.g., window light transmittance modulation waveform)  110 . This modulation scheme may also enhance privacy when exterior light  74  is a significant lighting source for illuminating interior  30 . Glare reducing light modulation (curve  110 ) may be used, for example, for side windows  16 . A driver of vehicle  10  may be viewing the exterior of vehicle  10  through a front window. To ensure that the driver can view external objects satisfactorily (e.g., when light  74  is associated with a headlight on vehicle  10  and/or nearby vehicles or is associated with a street light), window transparency may be increased (e.g., by increasing light transmittance and/or reducing haze) whenever light intensity  106  is high, as illustrated by illustrative window transparency modulation curve  108 . 
     The output of projector  54  may, if desired, be directed towards windows  16 . Windows  16  may include an adjustable haze layer and/or an adjustable light transmission layer. Light  56  from projector  54  may be modulated with an alternating-current modulation waveform (e.g., at 200 Hz), such as illustrative modulation curve  112  of  FIG. 7 . In synchronization, windows  16  may be modulated to exhibit reduced transparency (reduced light transmittance and/or increased haze) whenever a pulse of emitted light  56  is presence (see, e.g., curve  114 ). In this way, an occupant of vehicle  10  can view images on windows  16  that have been projected by projector  54 . 
     If the exterior of vehicle  10  is dark, curve  114  may be used to modulate windows  16  to maximize the reflection of light  56  back towards occupant  44  so that occupant  44  can view images projected onto window  56  by projector  54 . If the exterior of vehicle  10  is brighter, it may be desirable to use projector  54  and window  16  to form a heads up display. In this scenario, the transparency of windows  16  may be modulated in accordance with curve  114  or curve  114 ′. With curve  114 ′, the transparency of windows  16  is reduced less than with curve  114 , which enhances the overall transparency of window  16  and enhances the ability of occupant  44  to view external objects such as object  52  outside of vehicle  10  through window  16 . If the external scene viewed through window  16  is sufficiently bright and/or if the image projected by projector  54  is dim, window  16  may be modulated in accordance with cure  114 , which provides less overall transparency than curve  114 ′ but which maximizes reflected light by ensuring that window transparency is minimized when the light output of curve  112  is maximized. 
     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: 20170627
Publication Date: 20191126
Grant Date: 20191126
Priority Date: 20160728
Inventors: MELCHER, MARTIN
WILSON, JAMES R.
MAZUIR, Clarisse
Kingman, David E.
Assignee: APPLE INC
CPC Classifications: [{"code": "B60J3/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13306", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/137", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60J3/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60J3/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13318", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/1334", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13306", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/137", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13318", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60J3/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13306", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1334", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60J3/04", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 68617777