Electro-optical instruments for controlling the transmission and reflection of light

Abstract

The electro-optical instrument comprises a first active absorptive polarizer that electronically alters the absorption of a first polarization in response to a first applied voltage, and a second active absorptive polarizer that electronically alters the absorption of a second polarization in response to a second applied voltage, wherein the second polarization is substantially orthogonal to the first polarization. A static reflective polarizer is sandwiched between the first and second active absorptive polarizers, and the static reflective polarizer reflects the first polarization. The electro-optical instrument can switch between transmission, darkroom, reflection, and hybrid transmission-reflection states. One or both of the active absorptive polarizers may optionally be patterned into segments.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims priority to and any other benefit of U.S. Provisional Patent Application No. 63 / 458,766, filed on April 12, 2023, entitled "Electro - optical Device for Controlling Transmission and Reflection of Light", the entire disclosure of which is hereby incorporated by reference in its entirety.

[0002] Embodiments of the subject matter disclosed herein relate to systems and methods that use electro - optical devices for controlling the transmission or reflection of incident light, particularly for controlling the light transmission or reflection of windows, windshields, sunroofs, glasses, or other systems intended for transmissive viewing.

Background Art

[0003] In many situations, it is useful to control the intensity of light transmitted or reflected by windows, windshields, glasses, or other systems that require through-visibility, such as a person (or imaging device). For example, driving in bright sunlight is a common challenge. In this case, the driver may need to search for and wear sunglasses, move / adjust a car visor, or, alternatively, try to do their best to see under unsafe visual conditions (high glare, eye strain, eye discomfort, reduced contrast, difficulty seeing in-car displays, etc.). Wearing sunglasses may be helpful in bright sunlight, but they may also interfere with viewing information on the dashboard or a head-up display. Car visors have limitations in their shading range. Electronically dimmable windows are known and can be useful, but they can also interfere with head-up displays and are generally controlled as a unit. By darkening the entire window to make bright sunlight tolerable, other parts of the window may become darker than desired. In some cases, when the user is not driving the vehicle, a level of darkness far exceeding that provided by conventional dimmable windows, or other enhancements, may be required. In some situations, police, military, or aviation personnel may be subjected to harmful laser beams intended to blind or impair their vision. Conventional dimmable windows or glasses cannot address this. While some of these challenges have been discussed in the context of windows and windshields, other systems may face similar challenges.

[0004] Therefore, electronically controlled optical instruments with improved functionality are needed to manage the light that may occur accidentally in the system. [Overview of the project] [Means for solving the problem]

[0005] The electro-optical instrument comprises a first active absorptive polarizer that electronically alters the absorption of a first polarization in response to a first applied voltage, and a second active absorptive polarizer that electronically alters the absorption of a second polarization in response to a second applied voltage, wherein the second polarization is substantially orthogonal to the first polarization. A static reflective polarizer is sandwiched between the first and second active absorptive polarizers, and the static reflective polarizer reflects the first polarization. The electro-optical instrument can switch between transmission, darkroom, reflection, and hybrid transmission-reflection states. One or both of the active absorptive polarizers may optionally be patterned into segments.

[0006] These and other objects of the present invention will become apparent from the views of the drawings, the detailed description and the appended claims.

[0007] Refer to the attached drawings, in which specific embodiments of the subject matter provided and further advantages are described in more detail in the following specification. [Brief explanation of the drawing]

[0008] [Figure 1] A to D are non-limiting schematic cross-sectional diagrams of electro-optical devices in various device configurations according to several embodiments. [Figure 2] A and B are non-limiting schematic cross-sectional views of electro-optical devices in various device configurations according to several embodiments. [Figure 3] This is a plan view of a non-limiting example of a patterned second active-absorbing polarizer according to several embodiments. [Figure 4] This is a plan view of a non-limiting example of a gradient active absorption polarizer according to several embodiments. [Figure 5] This is a cross-sectional view of a non-limiting example of an active-absorbing polarizer according to several embodiments. [Modes for carrying out the invention]

[0009] definition In this specification, unless otherwise specifically defined, the definitions of optical parameters such as linear light, circularly polarized light, and unpolarized light are the same as those in *Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light*, Max Born, et al., Cambridge University Press; 7th edition (Oct. 13, 1999). Similarly, all liquid crystal technologies not specifically defined in this specification shall be defined as those used in *Licpiid Crystals Applications and Uses*, vol. 3 (edited by B. Bahadur) ("Bahadur"), published by World Scientific Publishing Co. Pte. Ltd., 1992.

[0010] An "absorbing polarizer" is a polarizer that absorbs selected polarizations. Absorbing polarizers have two axes, namely the absorption axis and the transmission axis, which are orthogonal to each other. Polarizations of light parallel to the absorption axis are absorbed more than polarizations parallel to the transmission axis.

[0011] For example, an "absorbent polarizer with an axis in the x-direction" means that the polarizer substantially absorbs polarization in the x-direction while substantially allowing transmission of polarization in the y-direction. The reverse is also true: an absorbent polarizer with an axis in the y-direction means that the polarizer substantially selectively absorbs y-polarized light and substantially transmits x-polarized light.

[0012] It should be noted that absorbing circular polarizers exist, and these are typically constructed by using a linear polarizer in combination with a quarter-wavelength retarder. When the light is polarized by the polarizer, the quarter-wavelength plate causes an a / 2 phase delay, thereby converting the linearly polarized light into circularly polarized light.

[0013] An "active" polarizer is used interchangeably with an "active absorptive polarizer" and refers to a polarizer that changes the absorption of selected polarizations in response to the applied voltage.

[0014] A controller connected to an active polarizer controls the polarization. In some embodiments, the polarizer is operated in an on or off state. In other embodiments, the polarizer can be configured to apply a modifiable polarization absorption level, which is set by a controller that sets a selected polarization level. In some embodiments, the polarization level of an active absorptive polarizer is selected by controlling the voltage applied to the active absorptive polarizer. Thus, the device may further include a controller for applying a voltage to the device, and the controller is connected to the active absorptive polarizer.

[0015] The reflectance and / or transmittance of the equipment can be controlled automatically, manually, or by a combination of both automatic and manual control.

[0016] A "reflective polarizer" is a polarizer that reflects a selected polarization more than other polarizations. For example, a "reflective polarizer with a reflection axis in the x-direction" means that the reflective polarizer reflects the polarization of the incident light in the x-direction more than the polarization of other y-directions. The reverse is also true: a "reflective polarizer with a reflection axis in the y-direction" means that the reflective polarizer reflects the polarization of the incident light in the y-direction more than the polarization of other x-directions.

[0017] A "passive" or "static" reflective polarizer always exhibits the same reflectivity, regardless of whether or not a voltage is applied to the device.

[0018] "High absorbance state" refers to a state in which an active absorbing polarizer is in or near its minimum transmittance state with respect to its light absorption profile (which can be narrowband or broadband based on the selection of a dichroic absorbent material, for example) and polarization. In some embodiments, the high absorbance state may have a light transmittance of 25%, 10%, 5%, 1%, 0.5%, 0.1%, 0.01%, or even less than 0.001% with respect to its light absorption profile and polarization. In some cases, the high absorbance state may have a transmittance in the range of 0.0001–0.001%, 0.001–0.01%, 0.01–0.1%, 0.1–0.5%, 0.5–1%, 1–5%, 5–10%, 10–15%, 15–20%, 20–25%, or any combination of these ranges, with respect to its light absorption profile and polarization.

[0019] A "low absorbance state" refers to a state in which an active absorbing polarizer is at or near its minimum transmittance state for its light absorption profile and polarization. In some embodiments, a low absorbance state may have a light transmittance at least 20% higher than the corresponding high absorbance state. In some cases, a low absorbance state may have a light transmittance of at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 85%, or 90%. In some cases, the high absorbance state may have light transmittances in the range of 10-15%, 15-20%, 20-25%, 25-30%, 30-35%, 35-40%, 40-45%, 45-50%, 50-55%, 55-60%, 60-65%, 65-70%, 70-75%, 75-80%, 80-85%, 85-90%, 90-95%, 95-97%, 97-99%, or any combination of these ranges, with respect to the light absorption profile and polarization.

[0020] A "narrowband" absorption profile refers to an absorbance spectrum characterized by a full width at half maximum (FMAX) of less than 175 nm when measured for an intended polarization, for example, in the range of 400–700 nm, or alternatively, within 400–1000 nm. Narrowband absorption profiles can impart hue or color to transmitted light.

[0021] A "broadband", or "broadband" absorption profile refers to an absorbance spectrum that, for example, when measured in the range of 400 - 700 nm, or alternatively within 400 - 1000 nm, has a full width at half maximum of 175 nm or more for the intended polarization. In some cases, the broadband absorption profile may have a substantially neutral color, but in some other cases, instead, it may impart a hue or color to the transmitted light.

[0022] P1 and P2 polarizations, or polarizations in the "x" and "y" directions, are arbitrary names and refer to the first and second linearly polarized or circularly polarized directions that are orthogonal to each other. These are used only for the sake of simplicity in the description of the present disclosure and do not refer to any fixed values of the directions. In some cases, the term "substantially orthogonal" can refer to linearly polarized or circularly polarized light within 15° from orthogonality, or within 10°, 5°, 3°, 2°, or 1°.

[0023] Conventionally, the properties of light are characterized by (i) the propagation direction indicated by the wave vector K, (ii) the wavelength indicated by λ, (iii) P1 and P2, the two orthogonal polarization directions, (iv) the polarization mode that can be unpolarized, circular / elliptical, or linear, and (iv) the energy carried within each polarization, indicated here by l1 and l2.

[0024] Generally, the term "polarization" refers to the vibration direction of the electric field of an incident light ray. The difference between linearly polarized, circularly polarized, and unpolarized light lies in how the unique representation of polarization is measured. Specifically, in a linearly polarized system, the vibration occurs in x or y, which is a single axial direction. In circular polarization, the vibration rotates in time or space, tracing a circle or an ellipse. In unpolarized light, the vibration direction cannot be uniquely defined. Unpolarized light is identified as light where (i) the amounts of both orthogonal polarizations are equal and (ii) the direction of polarization at any given time is random and cannot be defined.

[0025] It is well known that unpolarized light can be identified with light composed of two orthogonal circularly polarized beams (rightward or leftward) or two orthogonal linearly polarized beams (in the x and y directions). For illustrative purposes, in this application, light is described as being polarized in two directions to simplify the explanation of how the device operates. However, the device and principles described herein should be understood to apply to all light. In this application, “light” may refer to visible light having wavelengths of approximately 380–750 nm, but in some cases, light may also include near-infrared light. In some cases, “light” may refer to light having wavelengths in the ranges of 380–400 nm, 400–450 nm, 450–500 nm, 500–550 nm, 550–600 nm, 600–650 nm, 650–700 nm, 700–750 nm, 750–800 nm, 800–900 nm, 900–1000 nm, or any combination of these ranges.

[0026] As presented herein, unpolarized light is considered to consist of two linearly polarized elements in the x and y directions and propagate in the z direction. Furthermore, it should be noted that a reflective polarizer also has two axes, namely x and y (or P1 and P2). A reflective polarizer operates such that polarization is preferentially reflected when the polarization axis of light coincides with the axis of the reflective polarizer. When the polarization axis of light is perpendicular to the polarization axis of the reflective polarizer, that component is preferentially transmitted.

[0027] Note that in the case of circular light, x and y (or P1 and P2) refer to the left-right distinction of polarization, not a fixed direction in space. Therefore, x can represent, for example, a right circle, and y can represent a left circle. In the case of linearly polarized light, unpolarized light is considered to consist of equal amounts of left and right circularly polarized light. In this case, a reflective polarizer reflects either right or left circularly polarized light and transmits the other polarization (left or right), depending on its configuration.

[0028] Figures 1A-1D are non-limiting schematic cross-sectional views of an electro-optical device in various device configurations according to several embodiments. The electro-optical device 100 comprises a first active absorptive polarizer 110, a second active absorptive polarizer 120, and a static reflective polarizer 130 sandwiched between the first and second active absorptive polarizers. The first and second active absorptive polarizers may be independently controllable. For the sake of discussion, the figures show the components separated, but in various embodiments, these may be stacked. Though not shown, the electro-optical device 100 may be stacked in some cases, or otherwise mounted on a carrier or frame to form part of a system such as a window, windshield, sunroof, glasses, visor, helmet, lens, AR display, VR display, or several other suitable systems.

[0029] The first active-absorbing polarizer 110 can electronically change the absorption of the first polarization P1 of the incident light ray in accordance with the applied voltage. When the polarization P2 is substantially orthogonal to P1, the second polarization P2 of the incident light can be transmitted through the first active-absorbing polarizer regardless of the applied voltage, but there may be a smaller absorbance with a lower intensity than the P1 light. The second active-absorbing polarizer 120 can electronically change the absorption of the second polarization P2 of the light that can be incident on it in accordance with the applied voltage. The incident light with the first polarization P1 can substantially pass through the second active-absorbing polarizer regardless of the voltage, but there may be a smaller absorbance with a lower intensity than the P2 light. The static reflective polarizer 130 substantially reflects polarized P1 light (e.g., at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%) and substantially transmits polarized P2 light (e.g., at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%). In some cases, with respect to polarized P1 light, the static reflective polarizer 130 reflects 20-30%, 30-40%, 40-50%, 50-60%, 60-70%, 70-80%, 80-90%, 90-95%, 95-97%, 97-99%, or any combination of these ranges. In some cases, with respect to polarized P2 light, the static reflective polarizer 130 transmits 20-30%, 30-40%, 40-50%, 50-60%, 60-70%, 70-80%, 80-90%, 90-95%, 95-97%, 97-99%, or any combination of these ranges.

[0030] In some cases, in addition to the difference in polarization absorption, the optical absorption envelopes or spectra of the first and second active-absorbing polarizers may be substantially identical or different. “Substantially identical” means that the absorbance spectra in the corresponding high-absorbance states overlap by no more than 15% across the 400–700 nm range, or alternatively, across the 400–1000 nm range. For some applications, making the active-absorbing polarizers substantially identical with respect to absorption can provide the ability to generate very darkroom instrument conditions, which may be desirable. However, depending on the application, matching absorption spectra is not required. For example, one active-absorbing polarizer may have broadband (e.g., neutral) absorption, while the other active-absorbing polarizer may have narrowband (e.g., colored) absorption. In some preferred embodiments, there is at least some overlap between the absorption spectra of the first and second active-absorbing polarizers. In some cases, one or both active-absorbing polarizers may absorb some infrared radiation.

[0031] Figure 1A shows an electro-optical device 100 in a transmission state. Here, the first active-absorbing polarizer is in a high-absorbance state (110-P1), and the second active-absorbing polarizer is in a low-absorbance state (120-T). A user 180 may be in a space 160 adjacent to the first active-absorbing polarizer 110 and may want to view another space 150, for example, an outdoor environment with a strong light source 160 such as the sun, through the device 100. In an indefinite example, the electro-optical device may be part of a car's windshield system. Light from space 150, for example, sunlight 151, is unpolarized and may contain both polarized P1 and P2 light. Following the various arrows of light movement in Figure 1A (generally from right to left), both polarizations of the incident light 152 in the second active absorbing polarizer are substantially transmitted and can reach the static reflective polarizer 130, which transmits the P2 light and reflects the P1 light back to the second active absorbing polarizer. The P2 light reaching the first active absorbing polarizer is transmitted into space 160, which is easily observable by the user 180.

[0032] Light 161 in space 160 (which may include light sources other than light transmitted through the electro-optical device) is also unpolarized and may contain both polarizations P1 and P2. Following the various dashed arrows in Figure 1A (generally from left to right), the P1 component of light 162 incident on the first active-absorbing polarizer is substantially absorbed, while the P2 component can be substantially transmitted. The P2 component is also transmitted by the static-reflective polarizer 130 and the second active-absorbing polarizer 120. Thus, the user 180 receives only minimal reflection from the incident light 162, which creates a high-quality transmission state in which the user can easily see space 150 without being adversely affected by reflections that reduce contrast (or distract). In some embodiments, at least 10% of the P2 light incident on any of the active-absorbing polarizers, or at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%, may be transmitted through the optical instrument. In some embodiments, the amount of P2 light incident on any of the active-absorbing polarizers transmitted through the optical instrument 100 may be in the range of 20-30%, 30-40%, 40-50%, 50-60%, 60-70%, 70-80%, 80-90%, 90-95%, 95-97%, 97-99%, or any combination of these ranges. In some cases, there may be asymmetry, with a relatively large amount of P2 light transmitted from space 160 to space 150 rather than from space 150 to 160 (or vice versa).

[0033] Figure 1B shows the electro-optical instrument 100 in a transmission state. Here, the first and second active-absorbing polarizers are in a high-absorption state (110-P1 and 120-P2, respectively). Following the various arrows in Figure 1B (generally from right to left), the P2 component of the incident light 152 in the second active-absorbing polarizer can be substantially absorbed, while the P1 component can be transmitted. However, the P1 component is then reflected by the static-reflecting polarizer 130 and returns to the second active-absorbing polarizer. Thus, a relatively small amount of light of either polarization from space 150 reaches the observer 180.

[0034] Light 161 in space 160 may also contain both P1 and P2 polarizations. Following the various dashed arrows in Figure 1B (generally from left to right), the P1 component of light 162 incident on the first active absorbing polarizer is substantially absorbed, while the P2 component may be substantially transmitted. The P2 component is also transmitted by the static reflective polarizer 130 and the second active absorbing polarizer 120. Thus, only a small fraction of the light of either polarization from space 160 reaches space 150. This can provide the user 180 with substantial privacy and a high-quality darkroom instrument condition, for example, allowing the user to rest or sleep. In some embodiments, less than 15% of the light of either polarization incident on either active absorbing polarizer, or 10%, 5%, 1%, 0.5%, 0.1%, 0.01%, or even less than 0.001%, may be transmitted through the optical instrument. In some cases, when both active-absorbing polarizers are in a high-absorption state, the amount of light of any polarization incident on either active-absorbing polarizer transmitted through the optical instrument 100 may be in the range of 0.0001-0.001%, 0.001-0.01%, 0.01-0.1%, 0.1-0.5%, 0.5%-1%, 1-5%, 5-10%, 10-15%, or within these ranges.

[0035] Figure 1C shows the electro-optical instrument 100 in a reflective state. Here, the first active-absorbing polarizer is in a low-absorbance state (110-T), and the second active-absorbing polarizer is in a high-absorbance state (120-P2). As described with respect to Figure 1B, a relatively small amount of light of either polarization from space 150 reaches the observer 180. Light 161 in space 160 is unpolarized and may contain P1 and P2 of both polarizations. Following the various dashed arrows in Figure 1B (generally from left to right), both the P1 and P2 components of light 162 incident on the first active-absorbing polarizer can be transmitted. When the light reaches the static-reflective polarizer 130, the P2 component is substantially transmitted and then absorbed by the second active-absorbing polarizer 120. However, the P1 component is reflected by the reflective polarizer and returns to the user 180 through the first active-absorbing polarizer. Therefore, the user can use the device as a mirror and still maintain privacy. In some embodiments, at least 10%, or at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the P1 light incident on the first active absorbing polarizer is reflected back to the user through the static reflective polarizer. In some embodiments, the amount of P1 light incident on the first active absorbing polarizer that is reflected back to the user through the static reflective polarizer may be in the range of 10-20%, 20-30%, 30-40%, 40-50%, 50-60%, 60-70%, 70-80%, 80-90%, 90-95%, 95-97%, 97-99%, or any combination of these ranges.

[0036] Figure 1D shows the electro-optical device 100 in a hybrid transmission-reflection state. Here, the first and second active absorptive polarizers are in a low absorbance state (110-T and 120-T, respectively). As already mentioned above, some of the P2 light from space 150 reaches space 160 for the user to view the scenery. Furthermore, some of the P1 light from space 160 is reflected back to the user. Too much light being reflected can degrade the visual quality of space 150. However, in some cases, this reflected light can be useful, for example, when the electro-optical device is a parts system for reflecting a projected image (e.g., a windshield-type head-up display or AR / VR glasses). In some cases, the projected image itself can be P1 polarized, which allows light to be efficiently reflected back to the user, while still allowing a relatively small amount of light to enter space 150.

[0037] Although Figures 1A-1D describe the "low" and "high" absorbance states, in some embodiments, these active absorbing polarizers may have intermediate states that can be used to fine-tune the user's experience.

[0038] In some embodiments, one or both of the active absorbing polarizers may be patterned into individually addressable (controllable) segments or pixels. For example, Figures 2A and 2B are non-limiting schematic cross-sectional views of an electro-optical instrument in various instrument states according to some embodiments. Figure 2A shows an electro-optical instrument 100' in a fully transparent instrument state, similar to Figure 1A except that the second active absorbing polarizer 120' is patterned into various segments or portions. In this view, the three segments 120.1-T, 120.2-T, and 120.3-T are all in a low absorbance state. The instrument can operate in the same manner as discussed with respect to Figure 1A. In addition to unpolarized sunlight 151 that can be incident on the second active absorbing polarizer 120', Figure 2A also shows other unpolarized light 151' in space 150 incident on the second active absorbing polarizer. Unpolarized 151' may come from an area the user wants to see (e.g., a road). P2 polarization from both 151 and 151' can reach user 180. However, in some cases, sunlight 151 (or some other, strong light source) can be very distracting or dominant and may negatively affect the user's ability to see the light 151' from the area of ​​interest very well.

[0039] In Figure 2B, segment 120.3 is switched to its high absorbance state (123.3-P2). Segment 120.3 can be in the direct path between sunlight and the user's eyes. The main part of the optical instrument corresponding to segment 120.3 operates similarly to Figure 1B (darkroom instrument state), robustly blocking dazzling sunlight from the user, while still allowing excellent visual observation by the user through segments 120.1 and 120.3.

[0040] There are many possible configurations for the segments, and there are no specific limitations. Figure 3 is a plan view of a non-limiting example of a patterned second active-absorbing polarizer according to several embodiments. The second active-absorbing polarizer 120' may include, for example, 12 individually addressable segments: 10 in a low-absorbance state (120.1.1, 120.1.2, 120.1.3, 120.2.1, 120.2.2, 120.3.1, 120.3.2, 120.4.1, 120.4.2, 120.4.3) and 2 segments in a high-absorbance state (120.2.3, 120.3.3). Figure 2B may further show a cross-section of the column X=3 in Figure 3. The size and position(s) of the darkroom instrument portion may be selectable by the user, automatically selected, or a combination of these. In the case of a car's windshield, a second user (such as a passenger) may also have the option. In some cases, the electro-optical device may communicate with one or more sensors (such as a light sensor or an eye position sensor) that can partially measure which segment is being adjusted. In some cases, the dazzling object may not be the bright sun, but rather a distracting reflection, a vehicle with dazzling headlights, or even an adversarial laser intended to blind the user.

[0041] Although shown as having uniform size and shape, segments may have a variety of sizes or shapes. For example, segments may be triangles, pentagons, hexagons, or some other shape, rather than squares or rectangles. In some cases, for example in Figure 3, the size of a segment may be described by its longest axis, for example in Figure 3, the diagonal from corner to corner. The size of a segment depends in part on the nature of the equipment or system in which it is used. In some embodiments, the segments may range from 0.1–0.2 cm, 0.2–0.4 cm, 0.6–0.8 cm, 0.8–1.0 cm, 1.0–1.5 cm, 1.5–2.0 cm, 2–3 cm, 3–5 cm, 5–7 cm, 7–10 cm, 10–15 cm, 15–20 cm, 20–30 cm, 30–40 cm, 40–50 cm, 50–70 cm, 70 cm–1 m, 1–1.5 m, 1.5 m–2 m, 2–3 m, or any combination of these ranges, or in some cases, have a longest axis of more than 3 m or less than 0.1 cm. For eyeglasses, visors, and helmets, the segment size may be at the lower end of these ranges, while for car and building windows, the segment size may be at the upper end of these ranges. In some cases, the size of a segment may be defined relative to the length or width of the system in which the optical device is used (e.g., windows, windshields, sunroofs, glasses, visors, helmets, AR headsets, etc.). For example, in some cases, an optical device may contain 2-3, or 3-4, 4-5, 5-10, 10-20, 20-50, 50-100, or any combination of these ranges, or in some cases, more than 100 segments, across its length or width.

[0042] Instead of using segmentation or patterning, the second active-absorbing polarizer may be a gradient electro-optical device described, for example, in PCT Publication WO2022047371, filed on 31 August 2021, whose entire contents are incorporated herein by reference for all purposes. Figure 4 is a plan view of a non-limiting example of a gradient second active-absorbing polarizer according to several embodiments. For example, a gradient active-absorbing polarizer 220 may correspond to a second active-absorbing polarizer in an electro-optical device. Using the gradient technique, for example, a high-absorption state may be formed near one end 260 of the active-absorbing polarizer, and a low-absorption state may be formed at the opposite end 265. The gradual transition from high absorption to low absorption may occur across zone 267.

[0043] Although not shown, the first active absorbing polarizer may instead (or also) be patterned into individually addressable segments or pixels, or it may be a gradient electro-optical device. For example, referring again to Figures 1A-2B, there may be locations in the electro-optical device where the user desires good reflection of light (e.g., from a head-up display) in space 160, and other areas where the user desires limited reflection in order to see space 150 well.

[0044] In the devices described herein, switchable polarizers may, in some embodiments, be provided by using a guest-host system: a dichroic dye moiety associated with a nematic or chiral nematic liquid crystal (LC) material layer. For example, the dichroic dye moiety may be miscible with the LC, soluble in the LC, or even covalently bonded with the LC. In some embodiments, the dye molecules (guest) are oriented by the presence of the LC molecules (host). By applying an electric field to the layer, the LC molecules are reoriented, and the dye molecules follow this reoriented orientation. Such a stack may either absorb light of a certain polarization or be transparent. Suitable dyes that can be added to liquid crystal mixtures for this purpose are well known in the art. The preferential absorption of one polarization of light for other polarizations depends on the applied voltage.

[0045] The absorbing polarizer of the present invention is presumed to be active in that its polarization / absorption characteristics can be changed by the application of an external electric field (voltage). Furthermore, this active polarizer is based on a guest-host liquid crystal system or cell containing a negative dielectric anisotropic host combined with a positive dichroic dye in a homeotropically aligned cell. Alternatively, a positive dielectric anisotropic host can be used together with a positive dichroic dye in a planar aligned cell. The liquid crystal cell can be designed so that the transmittance of light passing through the cell changes by the application of voltage. For example, applying a low voltage or no voltage can cause the active absorbing polarizer to enter a high absorbance state, while applying a higher voltage can cause the active absorbing polarizer to enter a low absorbance state. Alternatively, an LC cell can be designed such that applying a low voltage or no voltage at all can cause the active absorbing polarizer to enter a low absorbance state, while applying a higher voltage can cause the active absorbing polarizer to enter a high absorbance state.

[0046] Figure 5 is a cross-sectional view of a non-limiting example of an active-absorbing polarizer according to several embodiments. The incident light 26 is at least partially absorbed by the active-absorbing polarizer 10 and passes through as transmitted (attenuated) light 27.

[0047] The active-absorbing polarizer 10 may include a pair of substrates 12a, 12b. As will be detailed later, the substrates may be independently selected and may include, for example, polymer materials, glass, or ceramics. A pair of transparent conductive layers, 14a, 14b, may be provided on or coated onto the surface of each substrate inside the cell. In some embodiments, optional passivation layers (which may optionally be called insulating layers or “hard coats”) 16a, 16b may be provided on each transparent conductive layer. The passivation layers may include, for example, non-conductive oxides, sol-gels, polymers, or composite materials. Optionally, orientation layers 18a, 18b may be provided on the passivation layers or transparent conductive layers. As a non-limiting example, the orientation layers may include polyimide. In some embodiments, the orientation layers may function as passivation layers. In some embodiments, the orientation layers may be rubbed to help orient an electro-optic material near the surface, such as an LC host, as is known in the art. In some embodiments, both orientation layers of the cell are rubbed. In some embodiments, the cell may contain only one brushed orientation layer.

[0048] The active-absorbing polarizer 10 includes an electro-optic material 25 provided between substrates. In the case of an active-absorbing polarizer, the electro-optic material can change from a state of low light transmittance to a state of high light transmittance in a specific wavelength range (and polarization) in response to a change in the electric field applied to the electro-optic material. The electric field can be changed, for example, by changing the voltage applied between a pair of transparent conductive layers 14a, 14b. In some embodiments, the electro-optic material is a liquid crystal guest-host ("LC-GH") material. As shown in Figure 5, in some embodiments, the LC-GH material may be in a state of highest light absorbance (dark state) when no voltage is applied. In some cases, using an LC host with positive anisotropy can provide an active-absorbing polarizer having a high absorbance state with a dark state at V=0. Conversely, using an LC host with negative anisotropy can produce an active-absorbing polarizer that is relatively transparent (low absorbance state) at V=0.

[0049] The substrate and the layers thereon define the cell gap 20 ("d"). In some embodiments (not shown), the cell may include spacer beads or other structures to maintain the gap. In some cases, the cell structure may be surrounded by a sealing material 13, such as a UV-curing optical adhesive or other sealants known in the art.

[0050] The conductive layer can be electrically connected to a variable voltage source schematically indicated by V1 enclosed in a circle. Figure 5 shows the cell power supply circuit with switch 28 open and no voltage applied, and the active absorbing polarizer in the dark state. When switch 28 is closed, a variable voltage or electric field can be applied to the liquid crystal guest host material 25.

[0051] Electro-optical materials Electro-optic materials are materials whose light absorption profile can be altered by applying an electric field. In some embodiments, electro-optic materials may include a guest host system having an LC host and a DC dye dissolved or dispersed therein, or alternatively, a dichroic light-absorbing moiety covalently bonded to the LC host (all considered guest host mixtures). Whether in the form of dissolution, dispersion, or attachment, such compositions may be called LC-GH materials or mixtures.

[0052] In some embodiments, the liquid crystal guest host comprises a mixture of a cholesteric or chiral nematic liquid crystal host and a dye material. The dye material may be characterized by dichroic properties and may contain a single dye or a mixture of dyes (DC light absorbing moiety) to provide these properties, as described later. In some embodiments, the liquid crystal guest host mixture may be formulated as a “narrowband mixture” for producing a color-absorbing polarizer, or as a “broadband mixture” for producing a generally neutral-absorbing polarizer. In the context of guest host materials, the term “mixture” is generally used broadly herein and may refer to a DC moiety covalently bonded to the LC host. The guest host mixture does not necessarily have to be a simple combination of individual dye molecules and liquid crystal molecules.

[0053] LC host In some embodiments, the host includes a chiral nematic or cholesteric liquid crystal material (including slightly twisted nematic LCs) (collectively referred to as "CLC") which may have negative dielectric anisotropy ("negative CLC") or positive dielectric anisotropy ("positive CLC"). In some embodiments of CLC, the liquid crystal material is cholesteric or includes a nematic liquid crystal combined with a chiral dopant. The CLC material has a twisted structure, i.e., a helical structure. The periodicity of the twist is called the "pitch" ("p"). The orientation or order of the liquid crystal host may be altered by the application of an electric field and can be used in combination with dye material to control or partially control the optical properties of an active absorption polarizer. In some embodiments, CLC may be further characterized by its chirality, i.e., right-handed chirality or left-handed chirality.

[0054] Dye materials To impart dichroic properties, the dye material typically contains at least one dichroic (DC) dye or a mixture of DC dyes (DC light-absorbing portion).

[0055] In some embodiments, the dye material may further contain small amounts of conventional absorbent dyes, for example, to provide the device with the desired overall hue in a transparent state. In some embodiments, the dye material contains substantially only DC dyes.

[0056] dc dye Dichroic dyes typically have an elongated molecular shape and exhibit anisotropic absorption. Generally, absorption is high along the long axis of the molecule, and such dyes may be called “positive dyes” or dyes that exhibit positive dichroism. Positive DC dyes are commonly used here. However, in some cases, negative DC dyes that exhibit negative dichroism may be used instead. In some embodiments, DC dyes (measured on a CLC host) may have a dichroism ratio of at least 5.0, or at least 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20.

[0057] The level of visible light absorption by a DC dye can be a function of the type of dye and the CLC host. In the case of the active-absorbing polarizer of this disclosure, the apparent absorption of visible light can also be a function of voltage. The orientation or long-range order of the CLC can be a function of the electric field or voltage across the entire thickness of the cell. Since the DC dye exhibits some degree of orientation with the CLC host, the apparent darkness of the cell can be altered by applying a voltage.

[0058] In some embodiments, DC dyes may comprise small molecule type materials (organic, inorganic, organometallic, metal-organic complexes, etc.). In some embodiments, DC dyes may comprise oligomer or polymer materials. The chemical site involved in light absorption may be, for example, a pendant group on the main chain. Multiple DC dyes may optionally be used, for example, to adjust the light absorption envelope or to improve overall cell performance in terms of lifetime or other properties. DC dyes may comprise functional groups that improve solubility, miscibility, or binding to the CLC host. Non-limiting examples of DC dyes include azo dyes, e.g., azo dyes having 2 to 10 azo groups, or 2 to 6 azo groups. Other DC dyes, such as anthraquinone dyes and perylene dyes, are also known in the art. Generally, any molecule exhibiting dichroism can be used.

[0059] In some embodiments, the guest-host mixture has a nematic-isotropic transition temperature (TNI) greater than 40°C. In other embodiments, the TNI is greater than 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C.

[0060] In some embodiments, an active absorbing polarizer, an order parameter S mix The mixture contains a guest-host mixture in which the ratio is 0.60, 0.65, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, or 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, or 0.85 or greater.

[0061] In some embodiments, the active-absorbing polarizer of the present disclosure may use a guest-host mixture which can be described as a “chiral planar”.

[0062] Other cell characteristics substrate Referring again to Figure 5, in some embodiments, substrates 12a and 12b are selected independently and may include one or both substrates, or non-flexible ceramics or glass. Flexible substrates may include plastics, flexible glass, or several other materials. The choice of material and its properties will vary to some extent depending on the application. The substrate must transmit visible light at least partially.

[0063] In some embodiments, the substrate may have low optical haze of less than 10% (or, in some embodiments, less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%) so that, when desired, a person or sensor can pass through the active-absorbing polarizer 10 and see clearly if necessary. In some embodiments, the substrate may optionally have some color or hue. In some embodiments, the substrate may have an optical coating on the outside of the cell. The substrate may be flexible or rigid.

[0064] In some non-limiting examples, plastic substrates may include polycarbonate (PC), blends of polycarbonate and copolymers, polyethersulfone (PES), polyethylene terephthalate (PET), cellulose triacetate (TAC), polyamide, p-nitrophenyl butyrate (PNB), polyetheretherketone (PEEK), polyethylene naphthalate (PEN), polyetherimide (PEI), polyarylate (PAR), polyvinyl acetate, cyclic olefin polymers (COP), or other similar plastics known in the art. In some non-limiting examples, flexible glass, including materials such as Corning® Willow® Glass, may be used as a substrate. The substrate may contain multiple materials or have a multilayer structure. In some embodiments, an active absorptive polarizer may use a plastic substrate having an optical delay with uniformity variation of less than ±20%, less than ±15%, or less than ±10% across the entire area of ​​the device.

[0065] In some embodiments, the substrate thickness may be in the range of 10-50 μm, 50-100 μm, 100-150 μm, 150-200 μm, 200-250 μm, 250-300 μm, 300-350 μm, 350-400 μm, 400-450 μm, 450-500 μm, 500-600 μm, 600-800 μm, 800-1000 μm, 1-2 mm, 2-3 mm, 3-4 mm, 4-5 mm, or greater than 5 mm, or any combination of these ranges.

[0066] Transparent conductive layer A “transparent” conductive layer refers to conductive layers 14a, 14b that generally transmit at least 45% of incident visible light. A transparent conductive layer is still useful even if it absorbs or reflects some of the visible light. In some embodiments, the transparent conductive layer may include a transparent conductive oxide (TCO) including but not limited to ITO or AZO. In some embodiments, the transparent conductive layer may include a conductive polymer including but not limited to PEDOT:PSS, polypyrrole, polyaniline, polyphenylene, or polyacetylene. In some embodiments, the transparent conductive layer may include a partially transparent thin layer of metal or metal nanowire, for example, formed of silver, copper, aluminum, or gold. In some embodiments, the transparent conductive layer may include graphene.

[0067] Enumerated embodiments Further embodiments of this specification include those listed below.

[0068] 1. Electro-optical instruments, A first active-absorbing polarizer that electronically changes the absorption of a first polarization in response to an applied first voltage, A second active-absorbing polarizer that electronically changes the absorption of a second polarization in response to an applied second voltage, wherein the second polarization is substantially orthogonal to the first polarization, and the second active-absorbing polarizer An electro-optical device comprising a static reflective polarizer sandwiched between the first active absorbing polarizer and the second active absorbing polarizer, wherein the static reflective polarizer reflects the polarization of the first polarizer.

[0069] 2. The apparatus according to Embodiment 1, wherein the apparatus can be configured to provide a transmission apparatus state, such that the first active-absorbing polarizer is in a high-absorbance state and the second active-absorbing polarizer is in a low-absorbance state, so that at least 10% of the light of the second polarization incident on either active-absorbing polarizer is transmitted through the apparatus.

[0070] 3. The apparatus according to Example 1 or 2, wherein the apparatus can be configured to provide a darkroom apparatus condition, and the first active-absorbing polarizer is in a high-absorbance state and the second active-absorbing polarizer is in a high-absorbance state, so that less than 15% of the light of any polarization incident on either active-absorbing polarizer is transmitted through the apparatus.

[0071] 4. The apparatus according to any one of embodiments 1 to 3, wherein the apparatus can be configured to provide a reflective apparatus state, such that the first active-absorbing polarizer is in a low-absorbance state and the second active-absorbing polarizer is in a high-absorbance state, i) at least 10% of the first-polarized light incident on the first active-absorbing polarizer is reflected through the static-reflective polarizer, and ii) less than 15% of the light of any polarization incident on the second active-absorbing polarizer is transmitted through the apparatus.

[0072] 5. The apparatus according to any one of embodiments 1 to 4, wherein the apparatus can be configured to provide a hybrid transmission-reflection apparatus state, such that the first active-absorbing polarizer is in a low-absorbance state and the second active-absorbing polarizer is in a low-absorbance state, so that i) at least 10% of the first-polarized light incident on the first active-absorbing polarizer is reflected, and ii) at least 10% of the second-polarized light incident on either active-absorbing polarizer is transmitted through the apparatus.

[0073] 6. When the device is in use, the user of the device is positioned in close proximity to the first active-absorbing polarizer, as described in any one of Embodiments 1 to 5.

[0074] 7. The apparatus according to any one of Embodiments 1 to 6, wherein the second active-absorbing polarizer includes individually addressable segments or pixels.

[0075] 8. The apparatus according to Embodiment 7, wherein at least one part of the optical apparatus is configured to provide one apparatus state, and at least one other part of the optical apparatus is configured to provide another apparatus state.

[0076] 9. The apparatus according to Embodiment 8, wherein at least one part corresponds to a darkroom apparatus state and at least one other part corresponds to a transmissive state.

[0077] 10. The apparatus according to any one of embodiments 7 to 9, wherein the size and position of at least one part are selectable by the user.

[0078] 11. The apparatus according to any one of embodiments 7 to 10, wherein the size and position of at least one part are automatically selected.

[0079] 12. The automatic selection is based in part on the position of the user's eyes relative to a strong light source, as described in Embodiment 11 of the apparatus.

[0080] 13. The apparatus according to any one of embodiments 1 to 12, wherein the first active-absorbing polarizer is in a high-absorbance state when the applied first voltage is low or off.

[0081] 14. The apparatus according to any one of embodiments 1 to 12, wherein the first active-absorbing polarizer is in a low-absorbance state when the applied first voltage is low or off.

[0082] 15. The apparatus according to any one of embodiments 1 to 14, wherein the second active-absorbing polarizer is in a high-absorbance state when the applied second voltage is low or off.

[0083] 16. The apparatus according to any one of embodiments 1 to 14, wherein the second active-absorbing polarizer is in a low-absorbance state when the applied second voltage is low or off.

[0084] 17. The apparatus according to any one of Embodiments 1 to 16, wherein at least one active absorbing polarizer comprises an electro-optic material including a dichroic light absorber and a liquid crystal host.

[0085] 18. The apparatus according to Embodiment 17, wherein the dichroic light absorber includes a dichroic dye portion covalently bonded to a liquid crystal host.

[0086] 19. The apparatus according to Embodiment 17 or 18, wherein the dichroic light-absorbing portion comprises a molecular dichroic dye mixed with a liquid crystal host.

[0087] 20. The apparatus according to any one of Embodiments 1 to 19, wherein the first active-absorbing polarizer is characterized by a first absorption spectrum, and the second active-absorbing polarizer is characterized by a second absorption spectrum.

[0088] 21. The apparatus according to Embodiment 20, wherein the first absorbance spectrum, when measured in the range of 400 to 1000 nm, includes a broadband absorption profile.

[0089] 22. The apparatus according to Embodiment 20, wherein the first absorbance spectrum, when measured in the range of 400 to 1000 nm, includes a narrowband absorption profile.

[0090] 23. The apparatus according to any one of embodiments 20 to 22, wherein the second absorbance spectrum, when measured in the range of 400 to 1000 nm, includes a broadband absorption profile.

[0091] 24. The apparatus according to any one of embodiments 20 to 22, wherein the second absorbance spectrum, when measured in the range of 400 to 1000 nm, includes a narrowband absorption profile.

[0092] 25. The apparatus according to any one of embodiments 20 to 24, wherein the first absorbance spectrum is substantially the same as the second absorbance spectrum when measured in the range of 400 to 1000 nm.

[0093] 26. The apparatus according to any one of embodiments 1 to 25, wherein at least one active absorbing polarizer is a gradient electro-optical instrument.

[0094] 27. A system comprising an electro-optical device as described in any one of Embodiments 1 to 26, wherein the system is a window, windshield, sunroof, glasses, visor, helmet, lens, AR display, or VR display.

[0095] 28. A method for changing the light transmittance using the apparatus described in any one of Embodiments 1 to 26, the method comprising controlling the voltages applied to the first and second active absorbing polarizers to provide a transmittance state, a darkroom state, a reflective state, or a hybrid transmittance-reflective state.

[0096] 29. The method according to Embodiment 28, wherein at least one active absorbing polarizer includes individually addressable segments, and the method further comprises selectively blocking a strong light source from the eye area of ​​the device user.

[0097] The specific details of particular embodiments can be combined in any suitable manner without departing from the spirit and scope of the embodiments of the present invention. However, other embodiments of the present invention may be directed to specific embodiments relating to each individual aspect, or to specific combinations of these individual aspects.

[0098] The above description of exemplary embodiments of the present invention is provided for illustrative and explanatory purposes only. It is not exhaustive and is not limited to the exact forms described herein, and many modifications and changes are possible in light of the above teachings.

[0099] The above description includes numerous details to facilitate understanding of various embodiments of the technology for illustrative purposes. However, it will be apparent to those skilled in the art that certain embodiments can be implemented by omitting some of these details or by adding additional details.

[0100] While several embodiments have been described, it will be understood by those skilled in the art that various modifications, alternative configurations, and equivalents can be used without departing from the spirit of the invention. Furthermore, to avoid unnecessarily obscuring the invention, many well-known processes and elements have been omitted from description. Moreover, details of a particular embodiment are not necessarily present in variations of that embodiment and may be added to other embodiments.

[0101] When used herein, phrases listing ranges of values ​​include the terminal values. For example, “between X and Y,” “range of X to Y,” and “X to Y” include X and Y. Or, the phrase “less than or equal to Y” includes Y. When a range of values ​​is provided, it is understood that each intervening value between the upper and lower limits of that range, up to 10 times the unit of the lower limit, is also specifically disclosed, unless the context otherwise clearly indicates. Each smaller range between any specified value or intervening value within a given range and any other specified value or intervening value within that given range is covered. The upper and lower limits of these smaller ranges may be independently included in or excluded from the range, and each range in which either, either, or both limits are included in the smaller range is also covered by the invention, according to the limits specifically excluded within the described range. Where a described range includes one or both limit values, ranges that exclude either or both of the included limit values ​​are also included.

[0102] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include multiple references unless the context clearly indicates otherwise. For example, a reference to “method” includes multiple such methods, and a reference to “layer” includes one or more layers and their equivalents known to those skilled in the art. The present invention has been described in detail for clarity and understanding. However, it can be understood that certain changes and modifications are possible within the scope of the appended claims.

[0103] All publications, patents, and patent applications cited herein are incorporated herein by reference in their entirety for all purposes and none are considered prior art. [Explanation of Symbols]

[0104] 10-Active Absorbing Polarizer 12a, 12b - Substrate 13-Encapsulation material 14a, 14b - transparent conductive layer 16a, 16b - protective layer 18a, 18b - Alignment layer 20-cell gap 25. Electro-optical materials 26-Incoming light 27-Transmitted Polarized 28-Switch P1 - First polarization P2 - Second Polarization 100-electronic optical equipment 110-First active absorbing polarizer 120 - Second Active Absorbing Polarizer 120'-Segmented second active-absorbing polarizer 120.1, 120.2, 120.3, 120.xy - Segments of the second active-absorbing polarizer (where x=1 to 4 and y=1 to 3) 130-Static reflective polarizer 150-space 151, 151' - Light in space 150 152, 152' - Incident light in the second active absorbing polarizer 160-space 161 - Light in space 160 162-Incident light in the first active absorbing polarizer 180-User 220-Gradation Active Absorbing Polarizer 260 - One end of a gradient active absorption polarizer 265 - Opposite end of a gradient active absorption polarizer 270 - Zone of Gradient Transitions

Claims

1. Electro-optical instruments, A first active-absorbing polarizer that electronically changes the absorption of a first polarization in response to an applied first voltage, A second active-absorbing polarizer that electronically changes the absorption of a second polarization in response to an applied second voltage, wherein the second polarization is substantially orthogonal to the first polarization, and the second active-absorbing polarizer An electro-optical device comprising a static reflective polarizer sandwiched between the first active absorbing polarizer and the second active absorbing polarizer, wherein the static reflective polarizer reflects the polarization of the first polarizer.

2. The apparatus according to claim 1, wherein the apparatus can be configured to provide a transmission apparatus state, wherein the first active absorbing polarizer is in a high absorbance state and the second active absorbing polarizer is in a low absorbance state, so that at least 10% of the light of the second polarization incident on either of the active absorbing polarizers is transmitted through the apparatus.

3. The apparatus according to claim 1, wherein the apparatus can be configured to provide a darkroom apparatus state, and the first active-absorbing polarizer is in a high-absorbance state and the second active-absorbing polarizer is in a high-absorbance state, so that less than 15% of the light of any polarization incident on either active-absorbing polarizer is transmitted through the apparatus.

4. The apparatus according to claim 1, wherein the apparatus can be configured to provide a reflective apparatus state, the first active absorbing polarizer being in a low absorbance state and the second active absorbing polarizer being in a high absorbance state, i) at least 10% of the first polarized light incident on the first active absorbing polarizer is reflected through the static reflective polarizer, and ii) less than 15% of the light of any polarity incident on the second active absorbing polarizer is transmitted through the apparatus.

5. The apparatus according to claim 1, wherein the apparatus can be configured to provide a hybrid transmission-reflection apparatus state, such that the first active-absorbing polarizer is in a low-absorbance state and the second active-absorbing polarizer is in a low-absorbance state, so that i) at least 10% of the first-polarized light incident on the first active-absorbing polarizer is reflected, and ii) at least 10% of the second-polarized light incident on either active-absorbing polarizer is transmitted through the apparatus.

6. The apparatus according to claim 1, wherein when the apparatus is in use, the user of the apparatus is positioned in close proximity to the first active absorbing polarizer.

7. The apparatus according to claim 1, wherein the second active-absorbing polarizer includes individually addressable segments.

8. The apparatus according to claim 7, wherein at least one part of the optical apparatus is configured to provide one apparatus state, and at least one other part of the optical apparatus is configured to provide another apparatus state.

9. The apparatus according to claim 8, wherein at least one of the parts corresponds to a darkroom apparatus state, and at least one other part corresponds to a transmission state.

10. The apparatus according to claim 7, wherein the size and position of the at least one part are selectable by the user.

11. The apparatus according to claim 7, wherein the size and position of at least one of the parts are automatically selected.

12. The apparatus according to claim 11, wherein the automatic selection is in part based on the position of the user's eyes relative to a strong light source.

13. The apparatus according to claim 1, wherein the first active-absorbing polarizer is in a high-absorbance state when the applied first voltage is low or off.

14. The apparatus according to claim 1, wherein when the applied first voltage is low or off, the first active-absorbing polarizer is in a low-absorbance state.

15. The apparatus according to claim 1, wherein the second active-absorbing polarizer is in a high-absorbance state when the applied second voltage is low or off.

16. The apparatus according to claim 1, wherein when the applied second voltage is low or off, the second active absorbing polarizer is in a low absorbance state.

17. The apparatus according to claim 1, wherein at least one active absorbing polarizer comprises an electro-optic material including a dichroic light absorber and a liquid crystal host.

18. The apparatus according to claim 17, wherein the dichroic light absorber includes a dichroic dye portion covalently bonded to the liquid crystal host.

19. The apparatus according to claim 17, wherein the dichroic light-absorbing portion includes a molecular dichroic dye mixed with the liquid crystal host.

20. The apparatus according to claim 1, wherein the first active-absorbing polarizer is characterized by a first absorption spectrum, and the second active-absorbing polarizer is characterized by a second absorption spectrum.

21. The apparatus according to claim 20, wherein the first absorbance spectrum, when measured in the range of 400 to 1000 nm, includes a broadband absorption profile.

22. The apparatus according to claim 20, wherein the first absorbance spectrum, when measured in the range of 400 to 1000 nm, includes a narrowband absorption profile.

23. The apparatus according to claim 20, wherein the second absorbance spectrum, when measured in the range of 400 to 1000 nm, includes a broadband absorption profile.

24. The apparatus according to claim 20, wherein the second absorbance spectrum, when measured in the range of 400 to 1000 nm, includes a narrowband absorption profile.

25. The apparatus according to claim 20, wherein the first absorbance spectrum is substantially the same as the second absorbance spectrum when measured in the range of 400 to 1000 nm.

26. The apparatus according to claim 1, wherein at least one active absorbing polarizer is a gradient electro-optical device.

27. A system comprising the electro-optical device described in claim 1, wherein the system is a window, windshield, sunroof, glasses, visor, helmet, lens, AR display, or VR display.

28. A method for changing the light transmittance using the apparatus described in claim 1, the method comprising controlling the voltages applied to the first and second active absorbing polarizers to provide a transmittance state, a darkroom state, a reflective state, or a hybrid transmittance-reflective state.

29. The method according to claim 28, wherein at least one active absorbing polarizer includes individually addressable segments, and the method further comprises selectively blocking a strong light source from the eye area of ​​the device user.

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