Staggered drive electrical control of multiple electrically controllable privacy glass structures

Abstract

An electrical driver can be used to provide electrical drive signals to the first and second electrically controllable optical privacy glass structures. The first electrical drive signal can be applied to the first privacy glass structure, and the second electrical drive signal can be applied to the second privacy glass structure. Applying the first and second electrical drive signals can include time-staggered delivery of the first and second electrical drive signals such that the peak power draw and / or peak current draw from the first privacy glass structure is offset in time from the peak power draw and / or peak current draw from the second privacy glass structure. The staggering can include delaying the application of one electrical drive signal relative to the other, phase-shifting one electrical drive signal relative to the other, or a combination thereof.

Description

[Technical field]

[0001] Related Articles This application claims the benefit of U.S. Provisional Patent Application No. 62 / 840,032, filed April 29, 2019, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to structures including electrically-controllable optically active materials, and more particularly to drivers for controlling electrically-controllable optically active materials. [Background technology]

[0003] Windows, doors, partitions, and other structures with controllable light modulation are gaining popularity in the market. These structures are commonly referred to as "smart" or "privacy" structures due to their ability to convert from a transparent state that allows users to see through the structure to a private state that inhibits viewing through the structure. For example, smart windows are used in luxury automobiles and homes to provide privacy control and visual darkening, and smart partitions are used as walls in office spaces.

[0004] A variety of different technologies can be used in smart structures to provide control over light transmission. For example, electrochromic, photochromic, thermochromic, suspended particle, and liquid crystal technologies have all been used in different smart structure applications to provide controllable privacy. These technologies generally use an energy source, such as electricity, to convert from a transparent state to a privacy state or vice versa.

[0005] In practice, electrical drivers can be used to control or "drive" the optically active material. The driver can apply or remove electrical energy to the optically active material to transition between the transparent and privacy states, or vice versa. Additionally, once the driver has transitioned to a particular state, it can apply electrical signals to the optically active material to help maintain that state. For example, the driver can apply electrical signals of alternating polarity to the optically active material to transition the optically active material between states and / or maintain the optically active material in a transition state.

[0006] Typically, a driver is configured to apply an electrical drive signal to one or more structures (e.g., privacy glass structures) that include an electrically controllable optically active material. Some structures have electrical characteristics such that the electrical drive signal applied thereto results in one or more current and / or power spikes at one or more corresponding times of the drive signal. Thus, a driver configured to simultaneously drive multiple structures must be able to accommodate the possibility that the current and / or power spikes associated with each of the multiple structures may occur simultaneously and place a large load on the driver. This may damage the driver, for example, due to a large amount of total current being provided. Additionally or alternatively, this may result in an inability to provide a desired drive signal to one or more corresponding drive structures (e.g., due to the driver reaching a maximum current output), which may result in an undesirable optical response from the electrically controllable optically active material. Summary of the Invention

[0007] In general, the present disclosure is directed to privacy glass structures incorporating electrically controllable optically active materials that provide controllable privacy. Privacy glass structures according to the present disclosure can be implemented in the form of windows, doors, skylights, interior partitions, or even other structures where controllable visible transmission is desired. In either case, the privacy structure can be fabricated from multiple panes of transparent material with an electrically controllable medium between the panes. Each pane of transparent material can carry an electrode layer, which can be implemented as a layer of electrically conductive, optically transparent material deposited on the pane. The optically active material can be controlled, for example, by controlling the application and / or removal of electrical energy to the optically active material, for example, via an electrical driver communicatively coupled to the electrode layer. For example, the driver can control the application and / or removal of electrical energy from the optically active material, which transitions the optically active material from a scattering state, in which visibility through the structure is inhibited, to a transparent state, in which visibility through the structure is relatively clear.

[0008] The electrical driver, sometimes referred to as a controller, may be designed to receive power from a power source, such as a rechargeable and / or replaceable battery and / or a wall or mains power source. The electrical driver may condition the electricity received from the power source, for example, by modifying the frequency, amplitude, waveform, and / or other characteristics of the electricity received from the power source. The electrical driver may deliver the conditioned electrical signal to electrodes electrically coupled to the optically active material. Additionally, in response to user input or other control information, the electrical driver may modify the conditioned electrical signal delivered to the electrodes and / or stop delivering electricity to the electrodes. Thus, the electrical driver may control the electrical signal delivered to the optically active material, thereby controlling the material to maintain a particular optical state or to transition from one state (e.g., a transparent or scattering state) to another state.

[0009] Aspects of the present disclosure include systems and methods for electrically driving a plurality of electrically controllable optical privacy glass structures using a single electrical driver. In some embodiments, the method includes establishing an electrical drive signal for each of the plurality of electrically controllable optical privacy glass structures, applying a first electrical drive signal to the first privacy glass structure, and applying a second electrical drive signal to the second privacy glass structure.

[0010] In some examples, applying the first and second electrical drive signals includes time-staggered delivery of the first and second electrical drive signals. Staggering the first and second electrical drive signals may cause a peak power draw and / or peak current draw from the first privacy glass structure to be offset in time from a peak power draw and / or peak current draw from the second privacy glass structure.

[0011] In some embodiments, the temporally staggered delivery of the first and second electrical drive signals includes applying the second electrical drive signal a predetermined amount of time after applying the first electrical drive signal. Additionally or alternatively, the temporally staggered delivery of the first and second electrical drive signals includes incorporating a phase shift between the first and second electrical drive signals.

[0012] In some examples, the established electrical drive signals may be analyzed to determine whether such electrical drive signals, when applied simultaneously and in phase, may cause an electrical parameter to exceed a predetermined threshold, such as a current spike value. In some such examples, such electrical drive signals may be applied simultaneously and in phase if such predetermined threshold would not be exceeded.

[0013] In some examples, the amount of temporal stagger between the first and second electrical drive signals is based on one or more parameters of the first and second electrical drive signals, such as frequency content of the first and second electrical drive signals. Staggering the electrical drive signals with respect to a frequency analysis of the signals can help reduce or eliminate superposition of one or more features of the electrical drive signals (e.g., state transitions of a square wave signal). [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a side view of an exemplary privacy glass structure. [Diagram 2] FIG. 2 is a side view of the exemplary privacy glass structure of FIG. 1 incorporated into a multi-pane insulating glass unit. [Diagram 3] 1A-1C are exemplary schematic diagrams illustrating example connection arrangements for drivers to electrode layers of a privacy structure. [Figure 4A] 1 illustrates an exemplary driver signal applied between a first electrode layer and a second electrode layer over time. [Figure 4B] 1 illustrates an exemplary driver signal applied between a first electrode layer and a second electrode layer over time. [Diagram 5] 1 illustrates an example driver configuration including a switching network and multiple energy storage devices in communication therewith. [Figure 6] 1 illustrates a driver in communication with multiple privacy glass structures. [Figure 7] FIG. 1 shows an example process flow diagram illustrating an example process for driving privacy glass structures with electrical drive signals based on characterization of the privacy structures. [Figure 8] 1 illustrates an exemplary classification of electrical characterizations of various privacy glass constructions and corresponding electrical drive signal parameters. [Figure 9] FIG. 1 illustrates a process flow diagram for updating an electrical drive signal provided to a privacy glass structure via an electrical driver. [Figure 10A]1 illustrates an example drive signal and resulting response current signal over time for a privacy glass structure. [Figure 10B] 1 illustrates an example drive signal and resulting response current signal over time for a privacy glass structure. [Figure 11A] 10A and 10B, respectively, including different display scales for ease of viewing. [Figure 11B] 10A and 10B, respectively, including different display scales for ease of viewing. [Figure 12] FIG. 1 shows a process flow diagram illustrating an exemplary process for determining one or more leakage current values. [Figure 13] FIG. 1 illustrates a process flow diagram illustrating an exemplary process for applying staggered electrical drive signals to multiple privacy glass structures. [Figure 14] An example implementation is shown of applying electrical drive signals to a plurality of privacy glass structures with determined amounts of stagger. [Figure 15] An example implementation is shown of applying electrical drive signals to a plurality of privacy glass structures with determined amounts of stagger. [Figure 16A] 1 illustrates example voltage versus time profiles of multiple electrical drive signals used to drive corresponding multiple privacy glass structures in the system. [Figure 16B] 1 illustrates example voltage versus time profiles of multiple electrical drive signals used to drive corresponding multiple privacy glass structures in the system. [Figure 16C] 1 illustrates example voltage versus time profiles of multiple electrical drive signals used to drive corresponding multiple privacy glass structures in the system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] In general, the present disclosure is directed to electrical control systems, devices, and methods for controlling optical structures having controllable light modulation. For example, the optical structures may include an electrically controllable optically active material that provides a controlled transition between a privacy or scattering state and a visible or transparent state. An electrical controller, or driver, may be electrically coupled to the optically active material through an electrode layer that constrains the optically active material. The electrical driver may receive electrical power from a power source and modulate the electricity received from the power source, for example, by modifying the frequency, amplitude, waveform, and / or other characteristics of the electricity received from the power source. The electrical driver may deliver the modulated electrical signal to the electrodes. Additionally, in response to user input or other control information, the electrical driver may modify the modulated electrical signal delivered to the electrodes and / or stop delivering electricity to the electrodes. Thus, the electrical driver may control the electrical signal delivered to the optically active material, thereby controlling the material to maintain a particular optical state or to transition from one state (e.g., a transparent or scattering state) to another state.

[0016] Examples of electrical driver configurations and electrical control functions are described in more detail in Figures 3-10. However, Figures 1 and 2 first describe an exemplary privacy structure that can utilize the electrical driver arrangements and electrical control functions described herein.

[0017] 1 is a side view of an exemplary privacy glass structure 12 including a first pane of transparent material 14 and a second pane of transparent material 16 with a layer of optically active material 18 constrained between the two panes of transparent material. The privacy glass structure 12 also includes a first electrode layer 20 and a second electrode layer 22. The first electrode layer 20 is carried by the first pane of transparent material 14 and the second electrode layer 22 is carried by the second pane of transparent material. In operation, electricity supplied through the first and second electrode layers 20, 22 can control the optically active material 18 to control visibility through the privacy glass structure.

[0018] The privacy glass structure 12 can utilize any suitable privacy material as the layer of optically active material 18. Additionally, while the optically active material 18 has been generally illustrated and described as a single layer of material, it should be understood that structures according to the present disclosure can have one or more layers of optically active material having the same or varying thicknesses. Generally, the optically active material 18 is configured to provide controllable and reversible optical obscuration and weight reduction. For example, the optically active material 18 can be an electronically controllable optically active material that changes visible transmittance directly in response to changes in electrical energy applied to the material.

[0019] In one example, the optically active material 18 is formed of an electrochromic material that changes opacity, and therefore light transmission properties, in response to a voltage change applied to the material. A typical example of an electrochromic material is WO 3 and MoO 3 These are usually colorless when applied to a substrate in a thin layer. The electrochromic layer can change its optical properties by oxidation or reduction processes. For example, in the case of tungsten oxide, protons can migrate within the electrochromic layer in response to a change in voltage, reducing the tungsten oxide to blue tungsten bronze. The color intensity varies with the magnitude of the charge applied to the layer.

[0020] In another example, the optically active material 18 is formed of a liquid crystal material. Different types of liquid crystal materials that can be used as the optically active material 18 include polymer dispersed liquid crystal (PDLC) materials and polymer stabilized cholesteric texture (PSCT) materials. Polymer dispersed liquid crystals usually involve phase separation of nematic liquid crystals from homogeneous liquid crystals that contain an amount of polymer sandwiched between electrode layer 20 and electrode layer 22. When the electric field is off, the liquid crystals are randomly scattering. This scatters light that enters the liquid crystal through the material and diffuses the transmitted light. When a certain voltage is applied between the two electrode layers, the liquid crystals can be homeotropically aligned, and the liquid crystals have increased light transmittance, allowing light to pass through the crystals.

[0021] For polymer stabilized cholesteric texture (PSCT) materials, the material can be either a normal mode polymer stabilized cholesteric texture material or a reverse mode polymer stabilized cholesteric texture material. In a normal polymer stabilized cholesteric texture material, light is scattered when no electric field is applied to the material. When an electric field is applied to the liquid crystal, it goes into a homeotropic state, causing the liquid crystal to reorient parallel to the direction of the electric field. This causes an increase in the light transmission of the liquid crystal, allowing light to pass through the liquid crystal layer. In a reverse mode polymer stabilized cholesteric texture material, the liquid crystal is transparent in the absence of an electric field (e.g., zero electric field), but becomes opaque and scattering upon application of an electric field.

[0022] In one example where the layer of optically active material 18 is implemented using liquid crystals, the optically active material includes liquid crystals and dichroic dyes to provide a guest-host liquid crystal mode of operation. When so configured, the dichroic dyes can act as guest compounds within the liquid crystal host. The dichroic dyes can be selected such that the orientation of the dye molecules follows the orientation of the liquid crystal molecules. In some examples, when an electric field is applied to the optically active material 18, there is little to no absorption in the short axis of the dye molecules, and when the electric field is removed from the optically active material, the dye molecules absorb in the long axis. As a result, the dichroic dye molecules can absorb light when the optically active material is transitioned to a scattering state. When so configured, the optically active material can absorb light that strikes the material to prevent an observer on one side of the privacy glass structure 12 from clearly observing activity occurring on the other side of the structure.

[0023] When the optically active material 18 is implemented using liquid crystals, the optically active material may include liquid crystal molecules within a polymer matrix. The polymer matrix may or may not be cured, resulting in a solid or liquid medium of polymer surrounding the liquid crystal molecules. Additionally, in some examples, the optically active material 18 may include spacer beads (e.g., microspheres), e.g., having an average diameter in the range of 3 micrometers to 40 micrometers, to maintain separation between the first pane of transparent material 14 and the second pane of transparent material 16.

[0024] In another example, where the layer of optically active material 18 is implemented using a liquid crystal material, the liquid crystal material becomes cloudy when transitioned to the privacy state. Such materials can scatter light that strikes the material to prevent an observer on one side of the privacy glass structure 12 from clearly observing activity occurring on the other side of the structure. Such materials can significantly reduce the visible specular transmittance (which may also be referred to as visible direct transmittance) through the material when in the privacy state compared to when in the light transmitting state, while only minimally reducing the total visible transmittance. With these materials, the amount of scattered visible light transmitted through the material increases in the privacy state compared to the light transmitting state, compensating for the reduction in the visible specular transmittance through the material. Visible specular transmittance or direct transmittance may be considered as the transmitted visible light that is not scattered or redirected through the optically active material 18.

[0025] Another type of material that can be used as the layer of optically active material 18 is a suspended particle material. Suspended particle materials are typically dark or opaque in an unactivated state, but become transparent when a voltage is applied. Other types of electrically controllable optically active materials can be utilized as the optically active material 18, and the disclosure is not limited in this respect.

[0026] Regardless of the particular type of material used for the layer of optically active material 18, the material can change from a light transmitting state, where the privacy glass structure 12 is intended to be transparent, to a privacy state, where the privacy glass structure 12 is intended to block visibility through the insulating glass unit. The optically active material 18 can exhibit a visible direct transmittance that gradually decreases as it transitions from a maximum light transmitting state to a maximum privacy state. Similarly, the optically active material 18 can exhibit a visible direct transmittance that gradually increases as it transitions from a maximum privacy state to a maximum transmitting state. The rate at which the optically active material 18 transitions from a generally transparent transmitting state to a generally opaque privacy state can be dictated by a variety of factors, including the particular type of material selected for the optically active material 18, the temperature of the material, the voltage applied to the material, etc.

[0027] To electrically control the optically active material 18, the privacy glass structure 12 in the example of FIG. 1 includes a first electrode layer 20 and a second electrode layer 22. Each electrode layer may be in the form of a conductive coating deposited on or across the surface of each respective pane that faces the optically active material 18. For example, the first pane 14 of transparent material may define an inner surface 24A and an outer surface 24B on opposite sides of the pane. Similarly, the second pane 16 of transparent material may define an inner surface 26A and an outer surface 26B on opposite sides of the pane. The first electrode layer 20 may be deposited across the inner surface 24A of the first pane, and the second electrode layer 22 may be deposited across the inner surface 26A of the second pane. The first and second electrode layers 20, 22 may be deposited towards the inner surface of the respective pane, or towards one or more interlayers, such as a blocker layer, that may be deposited between the inner surface of the pane and the electrode layer.

[0028] Each electrode layer 20, 22 may be a conductive coating that is a transparent conductive oxide ("TCO") coating, such as aluminum doped zinc oxide and / or tin doped indium oxide. The transparent conductive oxide coating may be electrically connected to a power source through a notch structure, as described in more detail below. In some examples, the transparent conductive coating forming the electrode layers 20, 22 defines walls of a cavity between the first pane of transparent material 14 and the second pane of transparent material 16 with which the optically active material 18 contacts. In other examples, one or more other coatings, such as a dielectric overcoat (e.g., silicon oxynitride), may be overlaid on the first and / or second electrode layers 20, 22. In either case, the first pane of transparent material 14 and the second pane of transparent material 16, as well as any coatings on the inner surfaces 24A, 26A of these panes, may form a cavity or chamber that contains the optically active material 18.

[0029] The panes of transparent material forming the privacy glass structure 12, including the first pane 14 and the second pane 16, are formed of any suitable material. Each pane of transparent material can be formed of the same material, or at least one of the panes of transparent material can be formed of a different material than at least one other of the panes of transparent material. In some examples, the panes of at least one (and optionally all) of the privacy glass structure 12 are formed of glass. In other examples, at least one (and optionally all) of the privacy glass structure 12 are formed of plastic, such as, for example, a fluorocarbon plastic, polypropylene, polyethylene, or polyester. When glass is used, the glass may be borosilicate aluminum glass, sodium-lime (e.g., sodium-lime-silicate) glass, or another type of glass. In addition, depending on the application, the glass may be clear or the glass may be tinted. Although the glass can be manufactured using different techniques, in some examples, the glass is manufactured on a float bath line, where molten glass is deposited onto a bath of molten tin to form and solidify the glass. Such an exemplary glass may be referred to as float glass.

[0030] In some examples, the first pane 14 and / or the second pane 16 may be formed from a number of different types of materials. For example, the substrate may be formed of laminated glass, which may include two panes of glass bonded together with a polymer such as polyvinyl butyral. Additional details regarding the arrangement of privacy glass substrates that may be used in the present disclosure may be found in U.S. Patent Application No. 15 / 958,724, entitled "HIGH PERFORMANCE PRIVACY GLAZING STRUCTURES," filed April 20, 2018, the entire contents of which are incorporated herein by reference.

[0031] The privacy glass structure 12 can be used in any desired application, including as a door, a window, a wall (e.g., a wall partition), a skylight in a residential or commercial building, or other application. To help facilitate installation of the privacy glass structure 12, the structure may include a frame 30 that surrounds the perimeter of the structure. In different examples, the frame 30 can be manufactured from wood, metal, or a plastic material such as vinyl. The frame 30 can define a channel 32 that receives and retains the peripheral edge of the structure 12.

[0032] In the example of Figure 1, the privacy glass structure 12 is shown as a privacy cell formed from two panes of transparent material constraining the optically active material 18. In other configurations, the privacy glass structure 12 can be incorporated into a multi-pane glass structure that includes a privacy cell having one or more additional panes separated by one or more inter-pane spaces. Figure 2 is a side view of an exemplary configuration in which the privacy glass structure 12 of Figure 1 is incorporated into a multi-pane insulating glass unit having spaces between the panes.

[0033] As shown in the illustrated example of FIG. 2, a multi-pane privacy glass structure 50 may include a privacy glass structure 12 separated from an additional (e.g., third) pane 52 of transparent material by a space 54 between the panes, e.g., by a spacer 56. The spacer 56 may extend around the entire perimeter of the multi-pane privacy glass structure 50 to hermetically seal the space 54 between the panes from gas exchange with the surrounding environment. To minimize heat exchange across the multi-pane privacy glass structure 50, the space 54 between the panes may be filled with an insulating gas or even evacuated of gas. For example, the space 54 between the panes may be filled with an insulating gas, such as argon, krypton, or xenon. In such applications, the insulating gas may be mixed with dry air to provide a desired ratio of air to insulating gas, such as 10 percent air to 90 percent insulating gas. In other examples, the space 54 between the panes may be evacuated such that the space between the panes is at a reduced pressure compared to the pressure of the environment surrounding the multi-pane privacy glass structure 50.

[0034] The spacer 56 can be any structure that holds the opposing substrates in a spaced apart relationship over the life of the multi-pane privacy glass structure 50 and seals the interpane space 54 between the panes of opposing material, for example to inhibit or eliminate gas exchange between the space between the panes and the environment surrounding the unit. One example of a spacer that can be used as the spacer 56 is a tubular spacer disposed between the first pane of transparent material 14 and the third pane of transparent material 52. The tubular spacer can define a hollow lumen or tube, which in some examples is filled with a desiccant. The tubular spacer can have a first side bonded to the outer surface 24B of the first pane of transparent material 14 (by a first bead of sealant) and a second side bonded to the third pane of transparent material 52 (by a second bead of sealant). The top surface of the tubular spacer can be exposed to the interpane space 54 and in some examples includes an opening that allows gas in the space between the panes to communicate with the desiccant material inside the spacer. Such spacers may be manufactured from aluminum, stainless steel, thermoplastic, or any other suitable material.

[0035] Another example of a spacer that can be used as the spacer 56 is a spacer formed from a corrugated metal reinforcing sheet surrounded by a sealant composition. The corrugated metal reinforcing sheet can be a rigid structural component that holds the first pane of transparent material 14 away from the third pane of transparent material 52. In yet another example, the spacer 56 can be formed from a foam material that is surrounded on all sides except the side that faces the space between the panes with the metal foil. As another example, the spacer 56 can be a thermoplastic spacer (TPS) spacer formed by placing a primary sealant (e.g., adhesive) between the first pane of transparent material 14 and the third pane of transparent material 52, followed by, optionally, a secondary sealant that is applied around the perimeter defined between the substrate and the primary sealant. The spacer 56 can have other configurations as will be understood by those skilled in the art.

[0036] Depending on the application, the first pane of transparent material 14, the second pane of transparent material 16, and / or the third pane of transparent material 52 (if included) may be coated with one or more functional coatings to modify the performance of the privacy structure. Exemplary functional coatings include, but are not limited to, low-emissivity coatings, solar control coatings, and photocatalytic coatings. Generally, low-emissivity coatings are coatings that are designed to allow near-infrared and visible light to pass through the pane while substantially preventing mid-infrared and far-infrared light from passing through the pane. Low-emissivity coatings may include one or more layers of infrared-reflective films interposed between two or more layers of transparent dielectric films. The infrared-reflective films may include conductive metals such as silver, gold, or copper. In contrast, photocatalytic coatings may be coatings that include a photocatalyst, such as titanium dioxide. During use, the photocatalyst may exhibit photoactivity that can aid in self-cleaning or reduce the maintenance of the pane.

[0037] The electrode layers 20, 22 of the privacy glass structure 12, whether implemented alone or in the form of a multi-pane structure with spaces between the panes, can be electrically connected to a driver. The driver can provide power and / or control signals to control the optically active material 18. In some configurations, wiring is used to establish an electrical connection between the driver and each respective electrode layer. A first wire can provide electrical communication between the driver and the first electrode layer 20, and a second wire can provide electrical communication between the driver and the second electrode layer 22. In general, the term wiring refers to any flexible electrical conductor, such as metal threads optionally covered with an insulating coating, flexible printed circuits, bus bars, or other electrical connectors that facilitate electrical connection to the electrode layers.

[0038] FIG. 3 is a schematic diagram showing an example connection arrangement between the driver and the electrode layers of the privacy structure. In the illustrated example, wires 40 and 42 electrically couple the driver 60 to the first electrode layer 20 and the second electrode layer 22, respectively. In some examples, the wires 40 and / or wires 42 can connect to their respective electrode layers through conduits or holes in the transparent panes adjacent to the electrode layers. In other configurations, the wires 40 and / or wires 42 can contact their respective electrode layers at the edges of the privacy structure 12 without requiring the wires 40 and / or wires 42 to extend through other sections (e.g., the transparent panes 14, 16) to reach the respective electrode layers. In either case, the driver 60 can be electrically coupled to each of the electrode layers 20 and 22.

[0039] In operation, the driver 60 can apply a voltage difference between the electrode layers 20 and 22, resulting in an electric field across the optically active material 18. The optical properties of the optically active material 18 can be adjusted by applying a voltage across the layers. In some embodiments, the effect of the voltage on the optically active material 18 is independent of the polarity of the applied voltage. For example, in some examples where the optically active material 18 includes liquid crystals that align with the electric field between the electrode layers 20 and 22, the optical consequences of the crystal alignment are independent of the polarity of the electric field. For example, the liquid crystals may align with the electric field with a first polarity and rotate approximately 180° when the polarity is reversed. However, the optical state (e.g., opacity) of the liquid crystals in either orientation may be approximately the same.

[0040] In some embodiments, the optically active material 18 behaves electrically similar to a dielectric between the first electrode layer 20 and the second electrode layer 22. Thus, in some embodiments, the first electrode layer 20, the optically active material 18, and the second electrode layer 22 together behave similar to a capacitor driven by the driver 60. In various examples, the privacy glass structure 12 may exhibit additional or alternative electrical properties, such as resistance and inductance, due to the structure itself and / or due to other features (e.g., contact resistance), such as due to the contact between the driver and the electrode layers 20, 22. Thus, in various embodiments, the privacy glass structure 12 electrically coupled to the driver 60 may behave similar to a capacitor, an RC circuit, an RLC circuit, and the like.

[0041] 4A illustrates an exemplary AC drive signal that may be applied between the first electrode layer 20 and the second electrode layer 22 over time. It will be understood that the signals in FIG. 4A are exemplary and are used for illustrative purposes, and that any of a variety of signals applied from the driver may be used. In the example of FIG. 4A, the voltage signal between the first and second electrode layers generated by the driver is an applied voltage V A and -V A In other words, in the illustrated example, the magnitude V A A voltage of is applied between the first and second electrode layers, and the polarity of the applied voltage alternates over time. The optical state of the optically active layer 18 (e.g., either transparent or opaque) may not change substantially while the voltage is applied to the optically active layer, even though the voltage applied to the layer varies over time. The optical state may not change substantially in that the unaided human eye may not detect a change to the optically active layer 18 in response to the alternating polarity of the current. However, if the driver stops delivering power to the optically active layer, the optically active layer 18 may change state (e.g., from transparent to opaque).

[0042] As shown in the example of FIG. 4A, the voltage polarity is V A From -V AInstead, the voltage changes polarity over a transition time 70 (shaded). In some instances, a sufficiently long transition time may result in an observable transition of the optically active material between polarities. For example, in an exemplary embodiment, liquid crystals within the optically active material may align with the electric field to create a substantially transparent structure that becomes substantially opaque when the electric field is removed. Thus, V A (Transparent) to -V A (transparent) when V A and -V A A sufficiently slow transition between -V A <V<V A (For example, |V|≪V A ), which may result in an observable optical state (e.g., opaque or partially opaque). A From -V A A sufficiently fast transition (to) may appear to an observer (e.g., the naked eye in real time) to result in no apparent change in the optical state of the optically active material.

[0043] FIG. 4B illustrates another exemplary AC drive signal that may be applied between the first electrode layer 20 and the second electrode layer 22 over time. The drive signal of FIG. A , 0, and -V A As shown, the input comprises a substantially tri-state square wave having states at V A and -V A During the transition time 72 between A and -V A Although shown to be much shorter than the duration of the drive signal in V, in various embodiments, the amount of time the signal is held at 0V (or another third state value) is longer than the duration of the drive signal in V A or -V A The amount of time the drive signal is held at 0 V (or another intermediate state) may be less than, equal to, or greater than the amount of time the drive signal is held at 0 V. In some examples, the amount of time the drive signal is held at 0 V (or another intermediate state) is short enough that the optically active material does not appear to change optical state.

[0044] In some examples, when maintaining a particular optical state (e.g., a transparent state), the polarities corresponding to the optical state (e.g., +V A and -V A Damage to the optically active material can be prevented by switching between an applied voltage (e.g., V A ) can be continuously switched between the applied polarities to maintain the desired optical state.

[0045] One technique for applying voltages of opposite polarity to a load (e.g., an optically active material) is via a switching network, such as an H-bridge configuration, as described in U.S. Provisional Patent Application No. 62 / 669,005, entitled ELECTRICALLY CONTROLLABLE PRIVACY GLAZING STRUCTURE WITH ENERGY RECAPTURING DRIVER, filed May 9, 2018, which is assigned to the assignee of the present application and is incorporated by reference in its entirety.

[0046] 5 illustrates an example driver configuration including a switching network and multiple energy storage devices in communication with the switching network. In the illustrated example, the driver 200 supplies a voltage V AThe power supply 210 includes a power source 210 shown to apply a voltage, a ground 220, and a switching network 230 used to drive a load 240, e.g., with opposite polarity. The switching network 230 can include one or more switching mechanisms that can selectively electrically connect and disconnect components on either side of the switching mechanism. In various embodiments, the switching mechanism can include a transistor, such as a metal oxide semiconductor field effect transistor (MOSFET). The power source 210 can be a DC power source (e.g., a battery), an AC power source (e.g., a wall or mains power source), or other suitable power source. The driven load 240 can be an electrically controllable optically active material 18 along with first and second electrode layers 20, 22.

[0047] In the example of FIG. 5, the switching network 230 includes a first switching mechanism SW1 coupled between the first side 235 of the load 240 and ground 220, and a second switching mechanism SW2 coupled between the second side 245 of the load 240 and ground 220. In some examples, the isolation component 224 can selectively prevent or allow current flow from the switching mechanisms SW1, SW2 to ground 220. The switching network 230 further includes a third switching mechanism SW3 coupled between the first side 235 of the load 240 and the power source 210, and a fourth switching mechanism SW4 coupled between the second side 245 of the load 240 and the power source 210. As used herein, it will be understood that a component "coupled to" or "coupled between" means at least an indirect electrical connection. However, unless otherwise specified, the terms "coupled to" or "coupled between" do not require that the "coupled" components are directly connected to each other.

[0048] 5 includes a first energy storage element SE1 shown in electrical communication with third and fourth switching mechanisms, SW3 and SW4, respectively, and a power source 210 on a first side, and a ground 220 on another side. An isolation component 212 is shown positioned to selectively enable or disable the flow of current between the power source 210 and other components of the driver 200, such as the first energy storage element SE1 or the third and fourth switching mechanisms.

[0049] The driver 200 further includes a second energy storage element SE2 coupled to the first side 235 of the load 240 and coupled between the third switching mechanism SW3 and the first switching mechanism SW1. Similarly, the driver includes a third energy storage element SE3 coupled to the second side 245 of the load 240 and coupled between the fourth switching mechanism SW4 and the second switching mechanism SW2.

[0050] In various embodiments, the energy storage elements may be electrical energy storage elements, such as inductive storage elements, capacitive storage elements, one or more batteries, etc. In some examples, storage elements SE1, SE2, and SE3 are the same. In other examples, at least one of SE1, SE2, and SE3 is different from the others. In some embodiments, SE1 includes a capacitive energy storage element, and SE2 and SE3 include inductive energy storage elements. In some such embodiments, SE2 and SE3 include matched inductive energy storage elements.

[0051] The driver 200 of FIG. 5 further includes a controller 260 in communication with the switching network 230. In the illustrated example, the controller 260 is in communication with each of the switching mechanisms (SW1, SW2, SW3, SW4). The controller 260 can be configured to control the switching operation of the switching mechanisms, for example, by opening and closing the switching mechanisms to selectively electrically connect or disconnect components on either side of each of the switching mechanisms. In various embodiments, the controller 260 can be configured to control series and / or parallel (e.g., simultaneous switching) switching mechanisms.

[0052] In some examples, the controller 260 is configured to control the switching mechanism to provide a voltage (e.g., from the power source 210) to a load 240, such as an optically active material in an electrically dynamic window. Furthermore, in some embodiments, the controller 260 can be configured to control the switching mechanism to periodically change the polarity of the voltage applied to the load 240. In some such examples, the operation of the switching network can be performed such that at least a portion of the energy discharged from the load (e.g., when changing polarity) can be recovered and stored in one or more energy storage elements SE1, SE2, SE3. Such recovered and stored energy can be used, for example, to perform a subsequent charging operation.

[0053] As described, in some embodiments, the driver 200 further includes additional components for selectively preventing the flow of current to various portions of the driver. For example, in the illustrated embodiment of FIG. 5, the driver 200 includes an isolation component 212 configured to selectively allow current flow between the power supply 210 and other portions of the driver. Similarly, the driver 200 includes an isolation component 224 configured to selectively allow current flow between the ground 220 and other portions of the driver 200. In some examples, the isolation components 212, 224 can be controlled via the controller 260 during various stages of driver operation. The isolation components can include any of a variety of suitable components for selectively allowing and / or preventing current flow between the various driver components. For example, in various embodiments, the isolation components 212, 224 can include switches, transistors (e.g., power MOSFETs), or other components or combinations thereof.

[0054] Other possible driver configurations are possible, such as omitting one or more of the above-referenced features, such as one or more energy storage elements, switches, etc. For example, in various examples, the driver can be configured to output an AC electrical drive signal without the need for switching elements.

[0055] FIG. 6 illustrates a driver 300 in communication with multiple privacy glass structures 310, 320, 330. In various embodiments, the driver 300 can be configured to communicate with the privacy glass structures 310, 320, 330 simultaneously, e.g., to control the operation of multiple structures simultaneously. Additionally or alternatively, the privacy glass structures 310, 320, 330 can be interchangeably placed in communication with the driver 300. For example, in an exemplary embodiment, the driver 300 can include an electrical interface that can couple any of the multiple privacy glass structures (e.g., 310, 320, 330) thereto. In some embodiments, the driver 300 can be configured to provide an electrical drive signal to each of the multiple privacy glass structures 310, 320, 330 to optically control such structures.

[0056] In some examples, the electrical drive signal provided from driver 300 to each privacy glass structure is limited for safety reasons, e.g., to comply with one or more safety standards. For example, in some embodiments, the electrical drive signal is power limited to meet one or more electrical safety standards, such as NEC Class 2. Providing a drive signal that meets one or more such safety standards allows for safe installation by a wider range of people, e.g., by allowing installation without the need for a qualified electrician.

[0057] In the illustrated example, each of the privacy glass structures 310, 320, 330 has one or more corresponding temperature sensors 312, 322, and 332, respectively, that can provide temperature information regarding the corresponding privacy glass structure. The temperature information can include, for example, contact temperature information (e.g., surface temperature) or non-contact temperature information (e.g., air temperature). In some examples, such temperature sensors 312, 322, 332 can provide such temperature information to the driver 300.

[0058] However, in some cases, different privacy glass structures have different electrical properties, e.g., due to different sizes, different materials, etc. As a result, the different structures may require different drive signals to operate effectively and / or efficiently. For example, in some embodiments, a drive signal that works well for a given privacy glass structure may result in poor optical performance for a different privacy glass structure due to differences between the structures.

[0059] In some examples, the driver may receive identification information from a privacy glass structure, e.g., from a memory storage component on the structure that contains the identification information readable by the driver. In some such examples, the driver may be configured to read such identification information and establish (e.g., from a look-up table stored in memory) an electrical drive signal for driving the identified structure. However, while providing a first order estimate regarding an appropriate drive signal for a given structure, in some cases, variations between similar structures (e.g., due to manufacturing variations, environmental factors, aging characteristics due to UV degradation, etc.) may result in different electrical characteristics between such similar structures. Thus, even two privacy glass structures of the same make / model may have different characteristics that may lead to inconsistencies between such structures when driven with the same electrical drive signal.

[0060] In some embodiments, the driver can be configured to characterize one or more properties of a privacy glass structure in communication with it to determine one or more drive signal parameters suitable for driving the privacy glass structure. For example, in some embodiments, the driver is configured to apply electrical sensing pulses to the privacy glass structure and analyze a response of the privacy glass structure to the electrical sensing pulses. The driver can be configured to characterize the privacy glass structure based on the analyzed response to the electrical sensing pulses. In some embodiments, the driver can be configured to characterize one or more parameters of the privacy glass structure based on the analyzed response, such as one or more electrical parameters.

[0061] 7 shows an example process flow diagram illustrating an example process for driving a privacy glass structure with an electrical drive signal based on a characterization of the privacy structure, the process including applying an electrical sensing pulse to the privacy glass structure (700).

[0062] The method of FIG. 7 further includes analyzing a response of the privacy glass structure to the applied electrical sensing pulse (702). In some examples, the electrical sensing pulse includes a voltage pulse (e.g., having a known voltage vs. time), and the analyzed response includes measuring a current through the privacy glass structure over the time that the voltage pulse is applied. Additionally or alternatively, the analyzed response can include measurements of voltage or current values ​​at a particular time (e.g., 40 milliseconds after the sensing pulse) or over a particular time range (e.g., 5-40 milliseconds after the sensing pulse) relative to application of the sensing pulse. In some examples, the time or period can be determined based on measured or estimated electrical parameters, such as resistance and capacitance values, thus capturing data within or over a particular period of time with respect to parameters, such as 10 RC time constants. The method further includes determining one or more electrical characteristics of the privacy structure (704). Such one or more electrical characteristics can include resistance, capacitance, inductance, or any combination thereof. For example, in some instances, the resistance value corresponds to a contact / lead resistance associated with applying an electrical signal to the electrode layers (e.g., 20, 22). Additionally or alternatively, the capacitance value can correspond to a capacitance of the optically active material 18 between electrode layer 20 and electrode layer 22. After determining the one or more electrical characteristics, the driver can be configured to load (706) one or more drive parameters for driving the privacy glass structure. The drive parameters can include one or more electrical drive signal parameters, such as voltage (e.g., peak voltage), frequency, slew rate, waveform, duty cycle, etc.

[0063] In some examples, characterizing the one or more electrical parameters includes determining a resistance value (e.g., equivalent series resistance), a capacitance value, and / or an inductance value associated with the privacy glass structure. In some such examples, the driver may be configured to generate a representative circuit that includes the one or more electrical parameters, such as an RC circuit or an RLC circuit. In some embodiments, loading (706) the one or more drive parameters may be performed based on the one or more electrical parameters so determined, e.g., based on one or more lookup tables and / or equations.

[0064] In some embodiments, loading (706) the one or more drive parameters includes establishing a drive signal. Additionally or alternatively, if a drive signal is currently in place, loading the one or more drive parameters can include adjusting one or more drive parameters of an existing drive signal. In various examples, adjusting the one or more parameters can include loading new values ​​for the one or more parameters, or can include a relative adjustment, such as increasing or decreasing a value associated with the one or more parameters with respect to the existing electrical drive signal.

[0065] Once the one or more parameters associated with the determined one or more electrical characteristics are loaded, the driver can be configured to apply an electrical drive signal including the loaded drive parameters to the privacy structure (708).

[0066] In some examples, the process of FIG. 7 can be performed multiple times. In some such examples, the analyzed response to the applied electrical sensing pulses (e.g., step 702) can include calculating a time-based value of the response, such as a time derivative or running average of the measured response (e.g., resulting voltage or current value). Additionally or alternatively, such response data can be filtered over time, e.g., to remove noise, outliers, etc. from data collected over time. Such time-based values ​​can be used to determine one or more electrical characteristics of the privacy structure.

[0067] In some embodiments, the process illustrated in FIG. 7 is executed during a start-up process of a privacy glass structure, such as during initial installation. An installer can connect a driver to the privacy glass structure, and the driver can execute the method illustrated in FIG. 7 to establish and apply an initial drive signal for the privacy glass structure. Such a process may be initiated manually and / or automatically. In some examples, the ability of the driver to determine and apply an appropriate electrical drive signal to the privacy glass structure eliminates the need for different drivers to drive different types of privacy glass structures, allowing the appropriate drive signal to be loaded without requiring specialized knowledge of which drive parameters may be suitable for a given privacy glass structure.

[0068] Figure 8 illustrates an example classification of electrical characterizations of various privacy glass structures, and corresponding electrical drive signal parameters. As shown in the example diagram of Figure 8, the structures can be classified according to low or high resistance values ​​and low or high capacitance values. In some examples, the drivers can be programmed with thresholds to specify which resistance values ​​are "low" and which resistance values ​​are "high," and similarly, which capacitance values ​​are "low" and which capacitance values ​​are "high."

[0069] One category of privacy glass structures shown in FIG. 8 includes low resistance and low capacitance. Such structures can include, for example, small structures (e.g., contributing to low capacitance values) with busbar contacts (e.g., contributing to low resistance values). In some cases, low resistance values ​​can lead to large current spikes when square waves or other sharp transition voltage signals are applied to the structure. Thus, the corresponding electrical drive signal can include one or more features to mitigate the risk of large current values, such as using a maximum current regulator, utilizing a slew rate square wave, and / or a pulse width modulation (PWM) signal (e.g., from a rail voltage). In some examples, a lower frequency electrical drive signal can be used to minimize average power consumption over time. One or more such features can properly charge small capacitive loads (e.g., capacitive electrically controllable optically active materials in privacy glass structures) to provide appropriate aesthetic structural behavior while reducing large current spikes.

[0070] Another category of structures in the example of FIG. 8 includes low resistance and high capacitance structures, such as large structures (having high capacitance values) and busbar contacts (contributing to low resistance values). Although such structures may be susceptible to large current spikes due to low resistance, the low resistance may facilitate the capacitors to be quickly filled with charge, providing a high quality aesthetic during operation of the structure. Similar techniques may be used to reduce the risk of current spikes, such as applying maximum current regulators, slew rate square wave signals, PWM signals, etc.

[0071] Another category of structures according to the example of FIG. 8 includes large structures with high resistance and high capacitance, e.g., point contacts (e.g., contributing to higher resistance values). In some such cases, the high resistance may limit current spikes, but may also make it more difficult to fill the capacitor with charge. Furthermore, because the capacitance is large, a large amount of charge may be required to quickly charge the structure for good aesthetic behavior. Thus, in some examples, the electrical drive signal may include an overdriven square wave. For example, in some embodiments, the electrical drive signal includes a square wave in which a portion of the square wave is overdriven. In an example implementation, within a square wave pulse, the first half of the pulse may be applied at a higher voltage than the second half of the pulse to more quickly fill the capacitor of the structure. Additionally or alternatively, a lower frequency waveform may be used to provide additional time for the large capacitor to be charged.

[0072] A fourth category of structures according to the example of FIG. 8 includes small structures with high resistance and low capacitance, e.g., point contacts. High resistance generally reduces large current spikes, and small capacitance generally allows for the relatively small amount of current required to fill the capacitor with charge to achieve good optical aesthetics. In some examples, such structures can be operated with a "default" electrical drive signal. In some embodiments, various electrical parameters can be adjusted and / or implemented to increase operational efficiency, such as incorporating voltage slew rates to mitigate excessive current peaks and minimize peak power consumption, and / or reducing frequency to mitigate average power consumption.

[0073] Although shown as two bins for two categories, it will be understood that any number of parameters can be analyzed and distinguished by any number of bins. For example, in general, a group of N parameters (in FIG. 8, N=2, resistance and capacitance) can be divided into M bins (in FIG. 8, M=2, low and high) within which the parameter values ​​may fall. The combination of the characteristics and the corresponding bins within which they may fall can be used to identify (e.g., via a formula or look-up table) an appropriate electrical drive signal for driving a privacy glass structure having such characteristics.

[0074] In some examples, a method similar to that shown in FIG. 7 can be repeated over time. Such a method can be performed manually or automatically (e.g., according to a preprogrammed schedule) to determine whether the drive signal should be updated based on changes in one or more electrical characteristics of the privacy glass structure. In some such examples, the existing drive signal can be stopped and a method similar to that shown in FIG. 7 can be performed to determine whether the drive signal should be updated. This can be performed manually or according to a schedule, for example, at night, when undesirable optical characteristics that may result from a disruption in operation may be overlooked. In some such embodiments, various data can be stored in memory, such as the determined characteristics of the privacy glass structure based on the response to the applied sensing pulses. In some examples, the characteristics of the privacy glass structure determined at the time of installation to establish the electrical drive signal are updated at an initial time t 0 is associated with.

[0075] 9 illustrates a process flow diagram for updating an electrical drive signal provided to a privacy glass structure via an electrical driver. In an exemplary implementation, the method illustrated in FIG. 9 can be performed after the driver has applied an existing drive signal to the privacy glass structure. The method of FIG. 9 begins at time t napplying (900) an electrical sensing pulse to the privacy glass structure at a time t n and determining (904) one or more electrical properties of the privacy glass structure at time t n The determined characteristics at the previous time t n-1 906. n-1 For a characteristic at time t n If the change in the characteristic at time t is less than or equal to the threshold amount (908), the driver continues to apply the existing electrical drive signal (910). n-1 and n If the change in the characteristic between is greater than a threshold amount (908), the driver can be configured to load and / or update one or more drive parameters to establish an updated electrical drive signal (912).

[0076] In some embodiments, the updated electrical drive signal may be updated at time t in a manner similar to loading one or more drive parameters based on the determined characteristics as described with respect to FIG. n Additionally or alternatively, loading / updating the one or more drive parameters to establish an updated electrical drive signal can include adjusting the one or more drive parameters based on the detected amount of change in the one or more electrical characteristics.

[0077] With reference to FIG. 9, at time t n-1 and time t nDetermining whether the change in one or more electrical characteristics between is greater than a threshold amount can be performed in a variety of ways. In some embodiments, each characteristic includes a corresponding absolute threshold difference that, if exceeded, causes a change in one or more parameters of the electrical drive signal. For example, in an exemplary embodiment, if the measured resistance value of one of the one or more electrical characteristics changes by more than 1000 ohms, the change is considered to be greater than the threshold amount. Additionally or alternatively, the change greater than the threshold amount can correspond to a rate of change of the characteristic. For example, in some embodiments, the one or more drive parameters can be updated in response to a resistance value increasing by at least 100%. In another example, the one or more drive parameters can be updated in response to a capacitance value changing by at least 10%.

[0078] In some embodiments, the change over time of each of the one or more parameters can be compared to a corresponding threshold value. In some examples, if any one characteristic differs from its previous value by a corresponding threshold amount, the change in the characteristic is deemed to be greater than the threshold amount and an updated electrical drive signal is established. In other examples, the amount of change in each of the one or more characteristics must be greater than a corresponding threshold amount in order for the change to be deemed greater than the threshold and for the electrical drive signal to be updated. In various embodiments, various combinations of the electrical characteristics (e.g., a subset of the multiple determined characteristics) can be analyzed to determine whether the change in the characteristic is greater than the threshold amount.

[0079] In some embodiments, loading / updating (912) one or more driving parameters can be based on additional tracking / measurement data 914. The tracking / measurement data 914 can include information such as the age of the privacy glass structure, the temperature of the privacy glass structure, etc. In some examples, the driver can be configured to adjust one or more driving parameters based on such data.

[0080] For example, in an exemplary embodiment, time t n-1 and time tn If the change in one or more electrical characteristics between is greater than a threshold amount, the driver can be configured to obtain temperature information (e.g., structure and / or environment temperature information) and update one or more drive parameters based on the temperature information. The temperature information can be received, for example, from a contact (e.g., thermocouple) or non-contact (e.g., infrared) temperature measurement device that outputs temperature information representative of the structure itself. Additionally or alternatively, the temperature information can be received from an ambient temperature sensor. In some examples, one or more temperature sensors can be associated with each of one or more privacy glass structures in the privacy system. For example, with respect to FIG. 6, the temperature sensors 312, 322, 332 can be configured to provide temperature information (e.g., contact and / or environment temperature information) associated with the corresponding privacy glass structures 310, 320, 330, respectively.

[0081] In addition to or as an alternative to temperature information, time t n-1 and time t n If the change in one or more electrical characteristics between is greater than a threshold amount, the driver can be configured to determine the age of the privacy glass structure and update one or more drive parameters based on the age of the structure. In some examples, the driver can be configured to flag the structure as aged, for example, when the structure has been operating for a predetermined amount of time and / or when the electrical characteristics are indicative of an aged structure. Age and / or temperature can be used in addition to or as an alternative to the determined electrical characteristics when determining the updated electrical drive signal.

[0082] 7 and 9, in various processes, the driver can be configured to apply electrical sensing pulses to the privacy glass structure to characterize the structure (e.g., to determine one or more electrical properties thereof). In some examples, characterizing the structure includes determining one or more electrical parameters of the structure, such as resistance, capacitance, etc., and in some such examples includes determining an equivalent circuit (e.g., an RC circuit, an RLC circuit, etc.) that represents the electrical properties of the structure.

[0083] In various embodiments, various electrical sensing pulses can be used to determine such characteristics. For example, in various examples, the electrical sensing pulses can include DC sensing pulses, low frequency drive signals (e.g., signals having similar characteristics such as drive signal amplitude or waveform, but lower frequency), or operational drive signals (e.g., currently implemented drive signals). In some embodiments, a user can select which type of electrical sensing pulse to use when characterizing a privacy glass structure.

[0084] In some cases, a DC sense pulse can provide the most accurate characterization because the DC signal can be applied over several RC time constants of the structure. In some embodiments, the DC pulse is applied to the structure for at least five time constants, but may be applied for a longer amount of time, such as at least 10 time constants, at least 100 time constants, at least 1000 time constants, or other values. While the exact value of the RC time constants may not be known in advance, in some examples, the privacy glass structure may have an expected range of time constants (e.g., associated with various structure sizes, types, etc.) that can be used, for example, to determine a minimum DC pulse length to increase the likelihood that the DC sense pulse will last at least a minimum number of time constants. A potential drawback of a DC sense pulse is that during the pulse, the visual aesthetics of the privacy glass structure may be degraded. However, this type of electrical sense pulse can be used, for example, during an installation procedure or when the structure is not in use, and a temporary degradation in the aesthetic appearance of the structure may be acceptable.

[0085] In some examples, the operational drive signal can be used as an electrical sensing pulse, such as one of the drive signals shown in Figures 4A and 4B. In an exemplary embodiment, such a drive signal can be applied at a frequency of about 45-60 Hz. In some such examples, such frequencies generally result in pulses that are too short to reach several RC time constants for characterization of the structure, and as a result, may provide less accurate characterization when compared to longer DC sensing pulses. However, because the operational drive signal is twice as long as the electrical sensing pulse, no aesthetic degradation occurs during the characterization process. Thus, characterization using the operational drive signal as the electrical sensing pulse can be performed during the day when viewing is more likely.

[0086] In some cases, a low frequency drive signal can provide a balance between a DC sense pulse and an operational drive signal as a sense pulse. For example, in some embodiments, reducing the frequency of the drive signal provides additional time to characterize the privacy glass structure's response to the signal without affecting the aesthetics of the privacy glass structure as severely as a longer DC sense pulse. In some examples, the low frequency drive signal has a frequency range of about 5-45 Hz. In some cases, a low frequency drive signal can still reduce the aesthetics of the privacy glass structure and therefore may be preferred for nighttime applications when the privacy glass structure is less likely to be viewed in a temporarily reduced aesthetic state.

[0087] In various embodiments, a user can manually initiate a privacy glass structure characterization process in which one or more electrical sensing pulses are applied to the privacy glass structure to determine one or more electrical characteristics of the structure, e.g., to determine or update an electrical drive signal. In some such examples, the user can select from a number of available electrical sensing pulse types, such as those described elsewhere herein. Additionally or alternatively, in some examples, the driver can be configured to automatically run the characterization process, e.g., according to a predetermined schedule (e.g., once an hour, once a day, once a week, etc.). In some such examples, the driver can be configured to run different characterization processes depending on when the process is run. For example, upon initial installation, the driver can apply a DC sensing pulse to initially characterize the structure and establish an electrical drive signal.

[0088] After installation, the driver can be configured to periodically apply electrical sensing pulses to characterize the structure, e.g., as described with respect to FIG. 9, to determine whether one or more characteristics of the structure have changed and / or whether the electrical drive signal should be updated. In some such examples, the driver can be configured to select which electrical sensing pulses to apply, e.g., depending on the time of day or other factors. For example, in some embodiments, the driver can be configured to apply a low frequency drive signal electrical sensing pulse, as described elsewhere herein, when the electrical sensing pulses are applied during one or more predefined intervals, such as when temporary aesthetic degradation is not likely to be noticed. Outside of the predefined time intervals, e.g., when temporary aesthetic degradation is likely to be noticed, the driver can be configured to apply an electrical sensing pulse that is an operational drive signal to reduce or eliminate any impact on the aesthetics of the structure during the characterization process.

[0089] In some examples, different update schedules may be implemented according to the processing capabilities of the system components used to perform the analyses For example, in some embodiments, an on-board processing component may have limited processing capabilities and may perform such analyses less frequently than a cloud-based processing system with greater processing resources.

[0090] In some examples, the cyclical characterization of the privacy glass structure over time can be used to track the operating and aging characteristics of the structure or adjust the electrical drive signal to correspond to changes in the characteristics, for example, as described with respect to FIG. 9. In some embodiments, the determined one or more electrical characteristics captured at multiple times may be stored in memory, for example, for comparison (e.g., as described with respect to FIG. 9), trend analysis, etc. In some embodiments, the driver can be configured to perform statistical analysis of the electrical characteristics over time and recognize patterns. The patterns can include trending of one or more electrical characteristics in a given direction over time (e.g., due to a failure of the structure), recurring trends (e.g., electrical characteristics that change during the day and night time periods, or seasonal changes with changes in ambient temperature, etc.). In some cases, the driver can similarly track and / or analyze additional data, such as ambient temperature or structure temperature data, and can be configured to correlate the electrical characteristics with such additional data.

[0091] Additionally or alternatively, in some implementations, the driver can be configured to periodically characterize aspects of the privacy glass structure at different rates throughout the life cycle of the structure. For example, in some cases, the driver characterizes the structure more frequently immediately after installation, during which the driver learns the behavior and / or typical characteristics of the structure, such as environmental effects on the structure's behavior (e.g., temperature, sunlight, etc.).

[0092] In some examples, the driver can be configured to detect or predict environmental changes (e.g., temperature changes, changes in ambient light, etc.) and can characterize the structure within a short period of time (e.g., within minutes or hours) to isolate the effects of a particular factor. For example, the driver can be configured to characterize the structure when the sun is obscured by clouds, and then characterize the structure again when the sun is no longer obscured to isolate the effects of sunlight on the structure's properties. The driver can be configured to detect such changes, for example, via one or more sensors and / or via data analysis (e.g., via Internet access to weather data).

[0093] Similarly, in an example implementation, the driver can be configured to detect and / or predict earthquakes (e.g., via an earthquake notification system and / or an Internet connection to one or more accelerometers or other sensors). The driver can be configured to characterize the structure after an earthquake is detected to assess damage or changes in operating characteristics. If the driver receives information (such as from a notification system) that an earthquake is imminent, the driver can characterize the structure before the earthquake occurs and again after the earthquake to specifically detect changes in structural characteristics due to the earthquake.

[0094] In some embodiments, the driver can be configured to recognize patterns in the electrical properties of the privacy glass structure over time and / or correlate the electrical properties of the privacy glass structure with other data, such as ambient temperature or structural temperature data. In some such examples, the driver can be configured to adjust / update one or more drive parameters of the electrical drive signal according to the statistical analysis and the recognized patterns and / or correlations. For example, the driver can be configured to automatically switch the electrical drive signal between summer and winter based on recognized changes in structural behavior over time. Additionally or alternatively, the driver can be configured to adjust one or more drive parameters based on received data, such as temperature data, based on observed correlations between the temperature data and structural properties.

[0095] A detected electrical event, such as an arcing event, power surge, power outage, lightning strike, or other event in the structure can trigger the driver to perform characterization to detect changes and / or damage to the structure.

[0096] In some examples, various electrical drive signal parameters can be adjusted based on tracked and / or measured data, such as aging data and / or temperature data. In some embodiments, such parameters can include voltage (e.g., RMS voltage and / or peak voltage), frequency, and / or rise time / slew rate. In various examples, loading / updating one or more drive parameters (e.g., step 912 of FIG. 9) includes one or more of the following:

[0097] Reducing the voltage value in response to an increase in temperature

[0098] Increasing the voltage value in response to a decrease in temperature

[0099] Increasing the voltage value as the structure ages

[0100] Decreasing the frequency value in response to an increase in temperature

[0101] Increasing the frequency value in response to a decrease in temperature

[0102] Decreasing frequency values ​​with increasing age of the structure

[0103] Increase slew rate / rise time as temperature increases

[0104] Reduce slew rate / rise time as temperature decreases

[0105] Reduce slew rate / rise time as the structure ages.

[0106] As an alternative or in addition to factors such as aging and temperature / seasonal changes in the operation of the privacy glass structure, other factors can be analyzed, such as a structural health metric. In some embodiments, the health metric includes a measure of leakage current through the structure. Leakage current can result from a number of issues, such as failure of a structural material, such as the optically active material 18, a faulty or broken coating, or other variable parts of the structure. Leakage current can be measured in a variety of ways. In an exemplary embodiment, a leakage current value can be determined based on an analysis of the current flowing through the privacy glass structure during a particular time.

[0107] 10A and 10B show an example drive signal and resulting response current signal of a privacy glass structure over time. As shown, a slew rate square wave voltage applied to the privacy glass structure results in a periodic current response. Although the signals are not necessarily shown to the same scale in FIGS. 10A and 10B, it is clear that the shape of the current signal through the privacy glass structure differs between FIGS. 10A and 10B. Such differences may indicate changes in leakage current through the privacy glass structure.

[0108] 11A and 11B show expanded views of the example current and voltage signals of FIGS. 10A and 10B, respectively, including different display scales for ease of viewing.

[0109] In some embodiments, one or more metrics associated with the current signal can be measured during a time when the structure is known to be in good operating condition, such as upon installation of the structure. Such metrics can include, for example, the time derivative or integral of the measured current at or over a given portion of the drive signal (e.g., during a positive voltage pulse). Additionally or alternatively, the difference in balanced current during the positive and negative portions of the square wave (represented as Δ in FIGS. 11A and 11B, respectively) can be measured. 1 and Δ 2 (denoted as ) can be used as a metric. For example, in some embodiments, the measured current response to an applied electrical drive signal includes measuring the current response during a predetermined portion of the applied drive signal, such as the period between transitions of an applied square wave. In some examples, this can avoid comparing current responses that include features (such as inrush currents) that may be present regardless of the state of the structure.

[0110] One or more current response metrics can be recorded over time to determine one or more leakage current values ​​associated with the structure. FIG. 12 shows a process flow diagram illustrating an example process for determining one or more leakage current values. In some examples, the method of FIG. 12 can be performed through a driver of a privacy glass structure. The method includes recording an initial time t 0 The method includes measuring 1200 a value associated with a current response signal of the healthy structure at time t. Such measuring may include determining the derivative or integral of the current and / or the difference between the balanced current during the positive and negative portions of the applied AC drive signal (e.g., a square wave). In some examples, 0 generally corresponds to a time when the structure is expected to be at or near peak health, such as during installation or initial operation.

[0111] Next, the methodn 1202, again measuring a value associated with the current response signal at time t 0 In the first instance after t 1 (n=1). For example, in some examples, 0 The first measurement after the initial measurement at time t 1 This method is carried out at time t 0 and t n Based on the determined value associated with the current signal at time t n For example, in some examples, determining the leakage current includes determining 1204 a leakage current at time t n vs. time t 0 Determine the difference in measurements at time t 0 and determining a change caused by leakage current that has occurred since measuring the value of the healthy structure in. In various examples, such a determination may be performed locally, for example via a driver, or may be made via cloud-based computing.

[0112] The method of FIG. 12 includes determining whether the leakage current meets a predetermined condition (1206). If the leakage current does not meet the predetermined condition, the driver continues to apply the existing electrical drive signal (1208). For example, in some instances, a leakage current that does not meet the predetermined condition may indicate that there is no leakage current or that the leakage current is small enough that the existing electrical drive signal can adequately drive the privacy glass structure without visible optical degradation. In some such cases, there is no need to modify the drive signal to compensate for the excessive leakage current.

[0113] However, in some examples, if the leakage current meets a predetermined condition, the method can include loading and / or updating one or more drive parameters to establish an updated electrical drive signal (1210). For example, in some examples, excessive leakage current can degrade the optical performance of the privacy glass structure, but can be compensated for by adjustments to the electrical drive signal.

[0114] Example adjustments to the electrical drive signal based on excessive leakage current can include increasing the voltage (1212), decreasing the frequency (1214), and / or pulsing the voltage (1216). In some examples, the voltage (e.g., V in FIG. 4) can be increased (1217). A By increasing the frequency, the voltage lost due to leakage current can be compensated for. Reducing the frequency provides additional time for the capacitive optically active material to charge, for example, during the positive portion of the square wave drive signal. In some examples, decreasing the frequency of the electrical drive signal includes increasing the period of the electrical drive signal. For example, with respect to the exemplary electrical drive signal shown in FIG. 4A, adjusting the electrical drive signal reduces the voltage V during each cycle. A and -V A This includes increasing the amount of time that the voltage is applied.

[0115] With respect to voltage pulsing, in some examples, the drive signal includes one or more floating steps, in which the optically active material is disconnected from the power supply and ground. For example, with respect to FIG. 5, in some examples, the drive signal can include a period in which, for example, all switches SW1, SW2, SW3, and SW4 are open, such that the load (e.g., the optically active material between the contact electrodes) maintains its current voltage. However, due to leakage current, the voltage at the load may droop during the floating steps. Pulsing the voltage (e.g., step 1216) can include modifying the electrical drive signal to include applying one or more voltage pulses to the load during one or more floating steps to maintain the voltage at the load and compensate for the voltage droop due to leakage current. In an exemplary implementation, the voltage drop from an expected value (e.g., voltage droop) across the structure can be measured and compared to a predetermined threshold. If the voltage droop meets or exceeds the predetermined threshold, a rail voltage pulse can be applied to the load. The frequency of applying the rail voltage pulse can depend on the severity of the droop (e.g., due to the severity of the leakage current). For example, in some cases, rail voltage pulses may be applied multiple times during a single cycle or half cycle of the applied electrical drive signal.

[0116] In various embodiments, the index n can be incremented and the steps of the process of FIG. 12 are repeated for multiple times t 1 , t 2 , …, t N In some cases, the time can be associated with one or more times (e.g., time t 0 …t N The measurements and / or leakage current values ​​(at any one or more of the following points) can be stored in a memory. Additionally or alternatively, the method can include generating a measurement curve of the measured leakage current versus time and / or versus index. In some examples, the trend of the leakage current over time can be used to determine information regarding possible causes of the leakage current.

[0117] In some embodiments, determining whether the leakage current satisfies a predetermined condition (e.g., step 1206) may include determining whether a single leakage current value satisfies a condition, such as the determined leakage current exceeding a threshold leakage current value or within a predetermined range of leakage current values. Additionally or alternatively, determining whether the leakage current satisfies a predetermined condition may include determining whether a trend of the leakage current versus time and / or a time index satisfies a predetermined condition, such as whether a derivative of the leakage current over time exceeds a predetermined threshold.

[0118] In some embodiments, one or more actions may be taken in response to leakage current satisfying a predetermined condition, as shown in steps 1212, 1214, and 1216. In some cases, different such actions or combinations thereof may be performed in response to different leakage current conditions, such as leakage current values ​​falling within different predetermined ranges and / or trends in leakage current over time that satisfy one or more predetermined conditions. In some embodiments, leakage current compensation may be initiated and / or altered by a user in the event that the privacy glass structure becomes optically degraded.

[0119] In some examples, nonlinearity in the current response to the applied voltage may be due to ionic behavior within the privacy glass structure. In some such examples, such nonlinear response may be analyzed to determine various parameters, such as the various sizes and / or densities of ions moving within the structure, and the response of such ions to an applied electric field within the structure. In some embodiments, such information may be used to determine details regarding optically active materials and how such materials decompose during operation causing optical degradation of the privacy glass structure. In some embodiments, data on leakage current over time may be used to determine one or more sources of leakage current, such as poor coating, ion generation, and / or other factors.

[0120] Various such calculations and / or decisions may be performed locally, for example via the driver, and / or may be performed in an external environment, such as via cloud-based computing.

[0121] As described with respect to FIG. 6, a single driver 300 can be configured to provide electrical drive signals to each of a plurality of privacy glass structures (e.g., 310, 320, 330) for simultaneous operation of such structures. As described herein, the driver can be configured to determine electrical characteristics of the privacy glass structures to establish appropriate electrical drive signals to drive such structures. In some embodiments, the driver can be configured to perform various such processes (e.g., as shown in FIGS. 7, 9, and / or 12) for each of a plurality of associated privacy glass structures. The driver can be configured to determine appropriate electrical drive signals for each of a plurality of privacy glass structures and to provide such electrical drive signals to each such privacy glass structure simultaneously.

[0122] As described elsewhere herein, in some examples, the electrical drive signal includes a square wave or approximately square wave (e.g., a square wave with a slew rate, a trapezoidal wave, a square wave shape with a slow zero crossover, etc.) signal. For example, the exemplary voltage versus time drive signals shown in FIGS. 4, 10A, and 10B show approximately square wave drive signals. Furthermore, as shown in FIGS. 10A and 10B, the transitions that occur every half period in the square wave drive signal result in spikes of current through the structure. Generally, considering a capacitive privacy glass structure, the steeper the edges of the square wave drive signal, the larger the corresponding current spikes can be. Thus, if multiple privacy glass structures are being driven simultaneously with a square wave or approximately square wave drive signal, the current spikes in each structure can occur at approximately the same time, generating large current / power peaks output from the driver.

[0123] In some embodiments, the driver is configured to stagger the electrical drive signals applied to one or more privacy glass structures to reduce peak current / power draw associated with a current response to the applied electrical drive signal. In other words, staggering the electrical drive signals can be done so that the peak current draw by each of the privacy glass structures driven by the driver occurs at different times. In some embodiments, staggering the second electrical drive signal relative to the first electrical drive signal includes delaying application of the second electrical drive signal relative to application of the first electrical drive signal when the first electrical drive signal and the second electrical drive signal are in phase with each other. In some examples, staggering the second electrical drive signal relative to the first electrical drive signal includes applying the first electrical drive signal and the second electrical drive signal substantially simultaneously while phase shifting the second electrical drive signal relative to the first electrical drive signal. In still further embodiments, staggering the second electrical drive signal relative to the first electrical drive signal includes phase shifting the second electrical drive signal relative to the first electrical drive signal and delaying in time the application of the second electrical drive signal relative to the application of the first electrical drive signal. Thus, in various embodiments, staggering the electrical drive signals can include phase shifting the signals, delaying in time the application of the signals, or a combination thereof.

[0124] 13 shows a process flow diagram illustrating an exemplary process for applying staggered electrical drive signals to a plurality of privacy glass structures. The method includes applying an electrical sensing pulse to each of a plurality of privacy glass structures (1300) and determining an electrical drive signal for each of the plurality of privacy glass structures (1302). Such steps may be performed for each of the privacy glass structures, for example, as described with respect to FIG.

[0125] The method of FIG. 13 further includes determining an amount of stagger for one or more privacy glass structures (1304). Such a determination may be performed in a variety of manners. In some examples, the driver may be configured to provide a predetermined amount of delay between the electrical drive signals of each privacy glass structure. Additionally or alternatively, in some examples, the driver may be configured to analyze the determined plurality of electrical drive signals to determine an appropriate amount of stagger for applying the plurality of electrical drive signals. For example, one or more parameters of each electrical drive signal, such as magnitude, frequency, etc., may be analyzed to determine an appropriate amount of stagger between the electrical drive signals, e.g., to reduce instances of signal overlap that may result in large current and / or power spikes. In some embodiments, an offset between the first electrical drive signal and the second electrical drive signal may be determined to compare frequency content of the first electrical drive signal and the second electrical drive signal to reduce or eliminate overlap of one or more features of the drive signals, such as transitions between states of a square wave drive signal.

[0126] In some examples, each of the multiple electrical drive signals for the corresponding multiple privacy glass structures is staggered with respect to the other signals, such that no two signals are applied simultaneously. In other examples, the driver may determine that two or more electrical drive signals can be applied simultaneously without resulting in undesirable current spikes (e.g., without resulting in a total current draw, such as a peak current draw, exceeding a predetermined threshold). In some such examples, the driver may be configured to provide such electrical drive signals simultaneously while potentially staggering other electrical drive signals.

[0127] The method of FIG. 13 further includes applying an electrical drive signal to each of the plurality of privacy glass structures, including the determined amount of staggering (1306). Including the amount of staggering in applying the electrical drive signal may include delaying application of the determined amount of staggering and / or phase shifting the electrical drive signal. As described, in some cases, the determined amount of staggering results in the plurality of electrical drive signals (e.g., a subset of the plurality of applied electrical drive signals) being applied simultaneously and in phase with one another to corresponding privacy glass structures, while other signals are staggered relative to the simultaneously applied signals. In other examples, each electrical drive signal is delayed and / or phase shifted relative to each of the other electrical drive signals.

[0128] In some embodiments, the driver can be configured to adjust one or more electrical drive signals to better stagger such signals. For example, as represented by the dashed lines in FIG. 13, the driver can be configured to determine (1304) an amount of staggering based on an adjusted electrical drive signal (e.g., an electrical drive signal different from that determined by the method of FIG. 7). Thus, in some such embodiments, the driver can be configured to determine (1302) an updated electrical drive signal after determining an appropriate amount of staggering to reduce peak current and / or power loading on the driver. In an exemplary embodiment, a first privacy glass structure is driven with an electrical drive signal having a first frequency and a second privacy glass structure is driven with an electrical drive signal having a second frequency different from the first. Staggering such signals by phase shift and / or delay may reduce current spikes associated with initial application of the respective electrical drive signals. However, the superposition of such electrical drive signals may nevertheless result in times during which undesirably large current and / or power spikes occur. In some examples, the driver may be configured to adjust one or both such electrical drive signals to reduce or eliminate such instances, e.g., adjust the electrical drive signals to include a common frequency and / or adjust the magnitude of one or both signals such that the resultant current and / or power spikes remain below a threshold level. Other techniques are possible for adjusting one or more electrical drive signals for the corresponding one or more privacy glass structures in response to the staggering analysis. In some such examples, upon adjusting one or more such electrical drive signals to reduce instances of undesirably large current and / or power spikes, a determined electrical drive signal including the determined amount of staggering may be applied to the respective privacy glass structures (1306).

[0129] Figures 14 and 15 show implementation examples of applying an electrically driven signal including a determined staggering amount to a plurality of privacy glass structures. Figure 14 shows a driver 1400 that is in electrical communication with privacy glass structures 1410, 1420, and 1430. In the illustrated example of Figure 14, the driver 1400 provides a common electrically driven signal f(t) to each of the privacy glass structures 1410, 1420, and 1430. For example, each of the privacy glass structures 1410, 1420, and 1430 can be of the same type and can have similar electrical characteristics, etc., and can have the same general electrically driven signal applied to each structure as determined by the method of Figure 7.

[0130] As shown in Figure 14, the electrically driven signal f(t) is phase-shifted between each privacy glass structure so that current spikes in each structure are simultaneously reduced or eliminated. For example, while the signal f(t) is provided to the privacy glass structure 1410, the signal f(t - Δt) is applied to the privacy glass structure 1420. Thus, various elements of the electrically driven signal and the resulting current response (e.g., current spikes) are delayed by an amount Δt in the privacy glass structure 1420 with respect to the privacy glass structure 1410. Similarly, the signal f(t - 2Δt) is applied to the privacy glass structure 1430, and as a result, the elements of the electrically driven signal and the resulting current response are delayed by Δt with respect to the privacy glass structure 1420 and by 2Δt with respect to the privacy glass structure 1410 in the privacy glass structure 1430.

[0131] In some examples, the staggering amount between each of the plurality of electrically driven signals is within one period of the electrically driven signal. For example, in the system of Figure 14 that includes privacy glass structures 1410, 1420, and 1430, and the electrically driven signal f(t) is periodic with a period T, and in some cases 2Δt < T. For example, if the frequency of the electrically driven signal f(t) is 60 Hz, in some examples, Δt < 8.3 ms. In yet further examples, the staggering amount between each of the plurality of electrically driven signals is within a half period of the electrically driven signal.

[0132] FIG. 15 illustrates a driver 1500 that provides electrical drive signals to each of a plurality of privacy glass structures 1510, 1520, and 1530. As shown, in some examples, different electrical drive signals f(t), g(t), and h(t) can be provided to the privacy glass structures 1510, 1520, and 1530, respectively. Such electrical drive signals can be determined for each privacy glass structure, for example, by the method illustrated in FIG. 7. The different electrical drive signals can include one or more different parameters, such as peak voltage, slew rate, waveform, frequency, etc. As described elsewhere herein, in some examples, the driver can determine the amount of stagger to apply between the different electrical drive signals, for example, based on a mathematical analysis of the determined electrical drive signals. In the illustrated example, the electrical drive signal g(t) applied to the privacy glass structure 1520 is staggered relative to the electrical drive signal f(t) by an amount Δt 1 and the electrical drive signal h(t) applied to the privacy glass structure 1530 is staggered relative to the electrical drive signal f(t) by an amount Δt 2 In various examples, the 1 is determined based on the determined electrical drive signal, depending on the amount of stagger, Δt 2 As described elsewhere herein, in some examples, different electrical drive signals may be applied simultaneously (e.g., Δt ) if the driver determines that the combined current response to such different electrical drive signals would not amount to undesirably large current and / or power spikes (e.g., greater than a predetermined threshold) due to, for example, a particular load size provided by a plurality of such privacy glass structures. 1 =0, Δt 2 = 0, and / or Δt 1 = Δt 2 ).

[0133] 16A-16C show examples of voltage versus time profiles of multiple electrical drive signals used to drive corresponding multiple privacy glass structures in a system. FIG. 16A shows a function f(t). FIG. 16B shows the function f(t) delayed by a time Δt such that the resulting signal may be represented by f(t-Δt). Similarly, FIG. 16C shows the function f(t) delayed by a time 2Δt such that the resulting signal may be represented by f(t-2Δt). In the illustrated example of FIGS. 16A-16C, the electrical drive signals f(t) are applied to separate the privacy glass structures with built-in staggering so that various transition portions of each electrical drive signal that may cause individual current and / or power spikes do not occur simultaneously.

[0134] In some embodiments, once the multiple drive signals are determined, the driver can determine which electrical drive signals, when applied simultaneously, cause one or more parameters (e.g., current spike values) to exceed a predetermined threshold. Similarly, the driver can determine which electrical drive signals, when combined, do not cause one or more parameters to exceed a predetermined threshold. The driver can determine which electrical drive signals can be applied simultaneously and stagger the application of the electrical drive signals or groups of electrical drive signals such that one or more parameters do not exceed a predetermined threshold when each electrical drive signal or group of electrical drive signals is applied.

[0135] In an exemplary embodiment, the driver is connected to power five privacy glass structures, three of which represent the largest loads that can be driven by the driver. The remaining two privacy glass structures are considered small and can be driven simultaneously without electrical parameters exceeding a predetermined threshold. The driver can be configured to provide electrical drive signals to these two smaller loads simultaneously and in phase with each other, while delivering each of the remaining three electrical drive signals staggered to the remaining structures.

[0136] Although shown in Figures 14, 15, and 16A-C as including three privacy glass structures, in general the system may include a driver and any number of privacy glass structures in communication therewith. The driver may be configured to perform various processes described herein for each of the one or more privacy glass structures in electrical communication therewith. In some examples, the driver may be configured to determine the number of privacy glass structures to which an electrical drive signal is to be provided. Such a determination may be used in determining various information, such as determining an appropriate electrical drive signal and / or amount of staggering for driving one or more privacy glass structures.

[0137] The driver can be configured to execute the processes described herein in various manners. In some examples, the system driver can include one or more components configured to process information, such as electrical signals and / or other received sensor information, and perform one or more corresponding actions in response thereto. Such components can include, for example, one or more processors, application specific integrated circuits (ASICs), microcontrollers, microprocessors, field programmable gate arrays (FPGAs), or other suitable components capable of receiving and outputting data and / or signals according to a predefined relationship. In some examples, the driver can include or otherwise communicate with one or more memory components, such as one or more non-transitory computer-readable media programmed with instructions to cause one or more such components to execute such processes. Additionally or alternatively, the driver can communicate with additional devices, such as external computer systems and / or networks, to facilitate information processing, such as cloud-based computing.

[0138] Various non-limiting examples have been described herein, and those skilled in the art will recognize that these and others fall within the scope of the following claims.

Claims

1. 1. A method for electrically driving a plurality of electrically controllable optical privacy glass structures using a single electrical driver, comprising: establishing an electrical drive signal for each of the plurality of electrically controllable optical privacy glass structures, each electrical drive signal including one or more drive parameters; applying a first electrical drive signal to a first privacy glass structure of the plurality of electrically controllable optical privacy glass structures, the first electrical drive signal being a periodic signal that generates periodic spikes in current through the first privacy glass structure, the first electrical drive signal being applied to maintain a particular optical state of the first privacy glass structure; applying a second electrical drive signal to a second privacy glass structure of the plurality of electrically controllable optical privacy glass structures, the second electrical drive signal being a periodic signal that generates periodic spikes in current through the second privacy glass structure, the second electrical drive signal being applied to maintain a particular optical state of the second privacy glass structure; The method, wherein applying the first electrical drive signal and the second electrical drive signal includes time-staggered delivery of the first electrical drive signal and the second electrical drive signal such that at least one of a peak power draw and a peak current draw from the first privacy glass structure is offset in time from a peak power draw and / or a peak current draw from the second privacy glass structure.

2. the first electrical drive signal comprises a first square wave and the second electrical drive signal comprises a second square wave; 2. The method of claim 1 , wherein the time-staggered delivery of the first and second electrical drive signals comprises offsetting in time timing of transitions between high and low states of the first and second square waves to offset in time current spikes associated with the electrical drive signals.

3. The method of claim 2 , wherein the first square wave comprises a first substantially tri-state square wave and the second square wave comprises a substantially tri-state square wave.

4. 4. The method of claim 1, wherein staggering the first and second electrical drive signals in time comprises applying the second electrical drive signal a predetermined amount of time after applying the first electrical drive signal.

5. establishing the electrical drive signal for each of the plurality of electrically controllable optical privacy glass structures; determining one or more electrical properties of the first privacy glass structure; determining the first electrical drive signal based on the determined one or more electrical characteristics of the first privacy glass structure; determining one or more electrical properties of the second privacy glass structure; and determining the second electrical drive signal based on the determined one or more electrical characteristics of the second privacy glass structure; 5. The method of claim 1, wherein the temporally staggered delivery of the first and second electrical drive signals comprises determining a temporal offset between the first and second electrical drive signals based on the determined first and second electrical drive signals.

6. 6. The method of claim 5, wherein determining the amount of temporal offset between the first electrical drive signal and the second electrical drive signal based on the determined first electrical drive signal and the second electrical drive signal comprises comparing a frequency component of the first electrical drive signal to a frequency component of the second electrical drive signal and determining a temporal offset to reduce or eliminate superposition of one or more features in the first electrical drive signal and the second electrical drive signal based on the compared frequency components.

7. 7. The method of any one of claims 1-6, wherein staggering the electrical drive signals applied to one or more of the electrically controllable optical privacy glass structures comprises incorporating a phase shift between a first electrical drive signal applied to a first privacy glass structure of the plurality of electrically controllable optical privacy glass structures and a second electrical drive signal applied to the second privacy glass structure of the plurality of electrically controllable optical privacy glass structures.

8. 8. The method of claim 7, wherein the first electrical drive signal is applied to the first privacy glass structure and the second electrical drive signal is applied simultaneously but out of phase to the second privacy glass structure.

9. 9. The method of claim 1, wherein staggering the electrical drive signals applied to one or more of the electrically controllable optical privacy glass structures comprises staggering each of the electrical drive signals such that none of the plurality of electrical drive signals is applied simultaneously and in phase with another of the plurality of electrical drive signals.

10. analyzing each of the plurality of electrical drive signals; determining which of the plurality of electrical drive signals can be applied simultaneously and in phase with one another without causing one or more electrical characteristics to exceed a predetermined threshold; 10. The method of claim 1, wherein staggering the electrical drive signals comprises staggering at least two electrical drive signals that cannot be applied both simultaneously and in phase without causing the one or more electrical properties to exceed the predetermined threshold with respect to each other.

11. the plurality of electrically controllable optical privacy glass structures includes a third privacy glass structure; establishing an electrical drive signal for each of the plurality of electrically controllable optical privacy glass structures includes establishing a third electrical drive signal for application to the third privacy glass structure; determining which of the plurality of electrical drive signals can be applied simultaneously and in phase without causing one or more electrical characteristics to exceed a predetermined threshold comprises: determining that combining the first electrical drive signal and the second electrical drive signal will cause the one or more electrical characteristics to exceed the predetermined threshold; and determining that combining the first electrical drive signal and the third electrical drive signal will not cause the one or more electrical characteristics to exceed the predetermined threshold; 11. The method of claim 10, wherein staggering at least two electrical drive signals that cannot be applied simultaneously and in phase without causing the one or more electrical characteristics to exceed the predetermined threshold relative to one another comprises staggering the first electrical drive signal and the second electrical drive signal while unstaggering the first electrical drive signal and the third electrical drive signal.

12. The method of claim 11, wherein the plurality of electrically controllable optical privacy glass structures includes a third privacy glass structure; establishing an electrical drive signal for each of the plurality of electrically controllable optical privacy glass structures includes establishing a third electrical drive signal for application to the third privacy glass structure; 11. The method of claim 1, wherein temporally staggering the electrical drive signals applied to the one or more of the electrically controllable optical privacy glass structures comprises staggering the application of the electrical drive signals substantially equally across each of a plurality of channels, including staggering the second electrical drive signal by a first amount from the first electrical drive signal and staggering the third electrical drive signal by the first amount from the second electrical drive signal.

13. The method of claim 12, further comprising determining which of the plurality of electrically controllable optical privacy glass structures are active; 13. The method of any one of claims 1 to 12, wherein staggering the electrical drive signals applied to one or more of the electrically controllable optical privacy glass structures comprises staggering the electrical drive signals relative to the active electrically controllable optical privacy glass structures.

14. The method of claim 1 , wherein the first electrical drive signal and the second electrical drive signal comprise different frequencies.

15. applying the first electrical drive signal to the first privacy glass structure to induce an inrush current spike from the single electrical driver to the first privacy glass structure; applying the second electrical drive signal to the second privacy glass structure to induce an inrush current spike from the single electrical driver to the second privacy glass structure; 15. The method of any one of claims 1 to 14, wherein the time-staggered delivery of the first electrical drive signal and the second electrical drive signal causes the inrush current spike from the single electrical driver to the first privacy glass structure to occur at a different time than the inrush current spike from the single electrical driver to the second privacy glass structure.

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