Waveguide display system with dynamic coloration.

Abstract

The display system may include a waveguide having an output coupler that couples image light out of the waveguide toward the eyebox. The output coupler may also transmit world light from real world objects toward the eyebox. The bias lens may pass the world light to the output coupler. An adjustable tint layer having multiple states with different amounts of world light transmission may be disposed between the bias lens and the output coupler. The different states may impart different colors to the world light and / or may impart gradient transmission properties. The bias lens itself may form the adjustable tint layer. The adjustable tint layer may have a transparent electrode layer that is supplied with one or more AC voltages that heat the adjustable tint layer. The adjustable tint layer may be a self-switching electrochromic device including a transparent solar cell.

Description

[Technical field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 298,873, filed January 12, 2022, which is incorporated by reference in its entirety herein. The present disclosure relates generally to optical systems, and more particularly to optical systems for electronic devices having displays. [Background technology]

[0002] Devices such as these can be difficult to design, and if care is not taken, the components used to display images in these devices may not exhibit the desired optical performance. Summary of the Invention

[0003] The electronic device may include a display system. The display system may include a display module that provides image light to a waveguide. The waveguide may propagate the image light via total internal reflection. An output coupler may couple the image light from the waveguide toward the eyebox. The output coupler may also transmit world light from a real-world object in front of the display system.

[0004] The bias lens may impart optical power to the world light while passing the world light to the output coupler. An electrically adjustable light modulator may be interposed between the bias lens and the output coupler. The electrically adjustable light modulator may be an adjustable tint layer having multiple states each with a different amount of world light transmission to the output coupler. The different states may impart different colors and / or gradient transmission characteristics to the world light, as desired. The different states may be used to mitigate different color blindness characteristics, as desired.

[0005] The adjustable tint layer may be laminated onto the bias lens, may be separated from the bias lens by an air gap, may be separated from the cover layer for the waveguide by an air gap, may be laminated onto the cover layer, or may form the cover layer itself. If desired, the bias lens itself may form the adjustable tint layer. The adjustable tint layer may have a transparent electrode layer to which one or more AC voltages are supplied that heat the adjustable tint layer. Different AC voltages may be applied to provide uniform heating. Heating the adjustable tint layer may maximize switching speed and / or perform de-hazing. The adjustable tint layer may be a self-switching electrochromic device, including a transparent solar cell, if desired. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 illustrates an exemplary system having a display in accordance with some embodiments.

[0007] [Diagram 2] FIG. 2 is a top view of an exemplary optical system for a display having a waveguide with an optical coupler and a bias lens, according to some embodiments.

[0008] [Diagram 3] 1 is a side cross-sectional view of an illustrative optical system having a waveguide and an adjustable tint layer on a bias lens in accordance with some embodiments.

[0009] [Figure 4] 1 is a side cross-sectional view of an illustrative optical system having a waveguide and a tunable tint layer separated from a bias lens by an air gap in accordance with some embodiments.

[0010] [Diagram 5] 1 is a cross-sectional side view of an illustrative optical system having a waveguide and having a tunable tint layer on a cover layer for the waveguide in accordance with some embodiments.

[0011] [Figure 6] 1 is a side cross-sectional view of an illustrative optical system having a waveguide and having a tunable tint layer forming a cover layer for the waveguide in accordance with some embodiments.

[0012] [Figure 7] 1 is a side cross-sectional view of an illustrative optical system having a waveguide and an adjustable tint layer forming a bias lens in accordance with some embodiments.

[0013] [Figure 8] 1A-1C are front views showing how an illustrative adjustable tint layer can transition between a clear state, a uniform dark state, and a gradient dark state, according to some embodiments.

[0014] [Figure 9] 1 is a side cross-sectional view showing how an illustrative adjustable tint layer, according to some embodiments, can include multiple layers that can be controlled to provide different tints to transmitted light. [Figure 10] 1 is a side cross-sectional view showing how an illustrative adjustable tint layer, according to some embodiments, can include multiple layers that can be controlled to provide different tints to transmitted light. [Figure 11] 1 is a side cross-sectional view showing how an illustrative adjustable tint layer, according to some embodiments, can include multiple layers that can be controlled to provide different tints to transmitted light.

[0015] [Figure 12] 1 is a state diagram illustrating how an exemplary tunable tint layer can transition between different states that impart different characteristics to transmitted light, according to some embodiments.

[0016] [Figure 13]1 includes plots of ocular response as a function of wavelength showing how an exemplary tunable tint layer, according to some embodiments, can transition between different states to compensate for different types of color blindness.

[0017] [Figure 14] 1 is a side cross-sectional view of an exemplary tunable tint layer that transitions between different states using a DC voltage, according to some embodiments.

[0018] [Figure 15] 1A-1C are front views illustrating how an example tunable tint layer that transitions between different states using a DC voltage can be heated using an AC voltage, according to some embodiments.

[0019] [Figure 16] FIG. 13 is a front view of an exemplary adjustable tint layer to which multiple AC voltages are provided to uniformly heat a surface area of ​​the adjustable tint layer, according to some embodiments.

[0020] [Figure 17] FIG. 2 illustrates a side cross-sectional view of an exemplary self-switching tunable tint layer powered using sunlight, according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The system 10 of FIG. 1 may be a head-mounted device (e.g., electronic device) having one or more displays. The displays in the system 10 may include a near-eye display 20 mounted in a support structure (housing) 8. The support structure 8 may have the shape of glasses or goggles (e.g., a support frame), may form a housing having a helmet shape, or may have other configurations that help mount and secure the components of the near-eye display 20 near the head or eyes of a user. The near-eye display 20 may include one or more display modules, such as display module 20A, and one or more optical systems, such as optical system 20B. The display module 20A may be mounted to a support structure, such as support structure 8. Each display module 20A may emit light 38 (image light) that is redirected toward the user's eye at the eyebox 24 using an associated one of the optical systems 20B.

[0022] The operation of the system 10 may be controlled using a control circuit 16. The control circuit 16 may include storage and processing circuitry that controls the operation of the system 10. The control circuit 16 may include storage devices such as, for example, hard disk drive storage devices, non-volatile memory (e.g., electrically programmable read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random access memory), etc. The processing circuitry of the control circuit 16 may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, graphic processing units, application specific integrated circuits, and other integrated circuits. Software code may be stored in the storage device of the circuit 16 and run on the processing circuitry of the circuit 16 to perform operations of the system 10 (e.g., data collection operations, operations involving the adjustment of components using control signals, image rendering operations to generate image content for display to a user, etc.).

[0023] The system 10 can include input / output circuitry, such as an input / output device 12. The input / output device 12 may be used to enable the system 10 to receive data from an external device (e.g., a tethered computer, a portable device such as a handheld or laptop computer, or other electronic device) and to enable a user to provide user input to the head-mounted device 10. The input / output device 12 may also be used to gather information about the environment in which the system 10 (e.g., the head-mounted device 10) is operating. Output components within the device 12 can enable the system 10 to provide output to a user and can also be used to communicate with external electronic devices. The input / output device 12 may include sensors and other components 18 (e.g., image sensors for collecting images of real-world objects that are digitally merged with virtual objects on the display of the system 10, accelerometers, depth sensors, light sensors, haptic output devices, speakers, a battery, wireless communication circuitry for communicating between the system 10 and the external electronic device, etc.). In some implementations described herein by way of example, sensors and other components 18 may include an image sensor (camera) and / or an ambient light sensor that senses the amount of light surrounding system 10 (e.g., whether system 10 is located in a dark room, a bright room, outdoors, etc.). These sensors may provide sensor signals to control circuitry 16. Control circuitry 16 may adjust one or more components in optical system 20B, such as one or more adjustable tint layers in optical system 20B, based on the sensor signals.

[0024] The display module 20A may be a liquid crystal display, an organic light emitting diode display, a laser-based display, or other type of display (e.g., a reflective display including one or more digital micromirror device (DMD) panels and / or liquid crystal on silicon (LCOS) panels, etc.). The display module 20A may be referred to herein as a display projector 20A, a light projector 20A, an image projector 20A, or a projector 20A. The optical system 20B may include lenses that allow an observer (e.g., see the observer's eyes at eyebox 24) to view images on the display(s) 20. There may be two optical systems 20B associated with each of the user's left and right eyes (e.g., to form a left lens and a right lens). Images for both eyes may be generated by a single display 20, or a pair of displays 20 may be used to display images. In a configuration having multiple displays (e.g., a left-eye display and a right-eye display), the focal length and position of the lenses formed by system 20B may be selected such that any gaps between the displays are invisible to the user (i.e., such that the image on the left display overlaps or merges seamlessly with the image on the right display).

[0025] If desired, optical system 20B may include components (e.g., optical combiners, etc.) that allow a real-world image or real-world image light from object 28 to be optically combined with a virtual (computer-generated) image, such as a virtual image in image light 38. In this type of system, sometimes referred to as an augmented reality system, a user of system 10 may see both real-world content and computer-generated content overlaid on the real-world content. Camera-based augmented reality systems may also be used within device 10 (e.g., in a configuration where a camera captures a real-world image of object 28 and this content is digitally merged with the virtual content on optical system 20B).

[0026] System 10 may, if desired, include wireless and / or other circuitry to support communication with a computer or other external device (e.g., a computer providing image content to display 20). In operation, control circuitry 16 may provide image content to display 20. The content may be received remotely (e.g., from a computer or other content source coupled to system 10) and / or may be generated by control circuitry 16 (e.g., text, other computer-generated content, etc.). The content provided to display 20 by control circuitry 16 may be viewed by an observer in eyebox 24 (e.g., at image light 38). Image light 38 may be, for example, light containing and / or representing a viewable thing, such as a scene or object (e.g., as modulated onto the image light using image data provided by control circuitry to the display module).

[0027] Figure 2 is a top view of an exemplary display that may be used in system 10 of Figure 1 (e.g., as display 20 of Figure 1). As shown in Figure 2, the display may include one or more display modules, such as display module(s) 20A, and an optical system, such as optical system 20B. Optical system 20B may include optical elements, such as one or more waveguides 50. Waveguides 50 may include one or more stacked substrates (e.g., stacked planar and / or curved layers, sometimes referred to herein as waveguide substrates) of optically transparent material, such as plastic, polymer, glass, etc.

[0028] Optionally, the waveguide 50 may also include one or more layers of a holographic recording medium (sometimes referred to herein as a holographic medium, grating medium, or grating medium) having one or more diffraction gratings recorded therein (e.g., a holographic phase grating, sometimes referred to herein as a hologram). The holographic recording may be stored as an optical interference pattern (e.g., alternating regions of different refractive index) in a photosensitive optical material such as a holographic medium. The optical interference pattern may produce a holographic phase grating that, when illuminated with a given light source, diffracts light to produce a three-dimensional reconstruction of the holographic recording. The holographic phase grating may be a non-switchable grating encoded with a persistent interference pattern, or it may be a switchable grating that can modulate the diffracted light by controlling an electric field applied to the holographic recording medium. If desired, multiple holographic phase gratings (holograms) may be recorded (e.g., superimposed) within the same volume of the holographic medium. The holographic phase grating may be, for example, a volume hologram or a thin film hologram in the grating medium. The grating medium may include photopolymer, gelatin such as dichromated gelatin, silver halide, holographic polymer dispersed liquid crystal, or other suitable holographic medium.

[0029] The grating on the waveguide 50 may include a holographic phase grating, such as a volume or thin film hologram, a metagrating, or any other desired grating structure. The grating on the waveguide 50 may also include a surface relief grating (SRG) formed on one or more surfaces of a substrate, a grating formed from a pattern of a metal structure, and the like. The grating may include, for example, multiple multiple gratings (e.g., holograms) that at least partially overlap within the same volume of the grating medium (e.g., to diffract light of different colors and / or from different ranges of input angles at one or more corresponding output angles). If desired, other light redirecting elements, such as louver mirrors, may be used in place of the grating in the waveguide 50.

[0030] As shown in FIG. 2, the display module 20A can generate image light 38 related to the image content displayed in the eyebox 24. The image light 38 can be collimated using a collimating lens, if desired. An optical system 20B can be used to present the image light 38 output from the display module 20A to the eyebox 24. If desired, the display module 20A can be mounted within the support structure 8 of FIG. 1, while the optical system 20B can be mounted between components of the support structure 8 (e.g., to form a lens that aligns with the eyebox 24). Other mounting configurations can be used, if desired.

[0031] Optical system 20B may include one or more optical couplers (e.g., optical redirecting elements), such as input coupler 52, cross coupler 54, and output coupler 56. In the example of Figure 2, input coupler 52, cross coupler 54, and output coupler 56 are formed in or on waveguide 50. Input coupler 52, cross coupler 54, and / or output coupler 56 may be fully embedded within a substrate layer of waveguide 50, partially embedded within a substrate layer of waveguide 50, or attached to waveguide 50 (e.g., attached to an outer surface of waveguide 50).

[0032] The waveguide 50 can guide the image light 38 down its length by total internal reflection. The input coupler 52 can be configured to substantially couple the image light 38 from the display module 20A into the waveguide 50 (e.g., all or a substantial amount of the image light 38), while the output coupler 56 can be configured to couple the image light 38 from within the waveguide 50 out of the waveguide 50 toward the eyebox 24 (e.g., as shown by light 48). The input coupler 52 can include an input coupling prism, an edge or face of the waveguide 50, a lens, a steering mirror or liquid crystal steering element, or any other desired input coupling element. For example, the display module 20A can emit the image light 38 in the +Y direction into the optical system 20B. When the image light 38 strikes the input coupler 52, the input coupler 52 can redirect the image light 38 so that the light propagates within the waveguide 50 via total internal reflection (e.g., in a direction +X within the total internal reflection (TIR) ​​range of the waveguide 50) toward the output coupler 56. When the image light 38 illuminates the output coupler 56, the output coupler 56 can redirect the image light 38 from the waveguide 50 toward the eyebox 24 (e.g., back along the Y axis). A lens, such as lens 60, can help direct or focus the image light 38 onto the eyebox 24. If desired, the lens 60 can be omitted. In a scenario in which the cross coupler 54 is formed on the waveguide 50, the cross coupler 54 can, for example, redirect the image light 38 in one or more directions as the image light 38 propagates along the length of the waveguide 50. In redirecting the image light 38 , the cross coupler 54 may also perform pupil widening on the image light 38 .

[0033] The input coupler 52, cross coupler 54 and / or output coupler 56 may be based on reflective and refractive optics or based on diffractive (e.g., holographic) optics. In configurations where couplers 52, 54 and 56 are formed from reflective and refractive optics, couplers 52, 54 and 56 may include one or more reflectors (e.g., arrays of micromirrors, partial mirrors, louver mirrors or other reflectors). In configurations where couplers 52, 54 and 56 are based on diffractive optics, couplers 52, 54 and 56 may include diffraction gratings (e.g., volume holograms, surface relief gratings, etc.).

[0034] The example of Figure 2 is merely illustrative. Optical system 20B may include multiple waveguides stacked laterally and / or vertically relative to one another. Each waveguide may include one, two, all, or none of couplers 52, 54, and 56. Waveguide 50 may be at least partially curved or bent as desired. One or more of couplers 52, 54, and 56 may be omitted.

[0035] As shown in FIG. 2, the waveguide 50 and output coupler 56 can be mounted between an outer optical element, such as the outer lens 42, and an inner optical element, such as the inner lens 44. The lenses 42 and 44 can be formed, by way of example, from glass or polymer. The inner lens 44 can have a negative bias component and / or a user-specific eyeglass prescription component. Accordingly, the inner lens 44 may be referred to herein as a negative bias lens 44, a prescription lens 44, or simply as lens 44. The outer lens 42 can have a positive bias component that is equal and opposite to that of the negative bias component. Accordingly, the outer lens 42 may be referred to herein as a positive bias lens 42 or simply as lens 42. As an example, the outer lens 42 may have a bias component of +1 diopter and the inner lens 44 may have a bias component of −1 diopter. When viewing a real world image from the eyebox 24 through the optical system formed from the lenses 42 and 44 and the waveguide 50, these two bias components cancel each other out. If the user has a vision impairment (e.g., myopia or hyperopia), vision correction can be achieved by combining the user's prescription with the negative bias component of the inner lens 44. Alternatively, the inner lens 44 may include only the negative bias component.

[0036] As an example, consider a scenario in which a user is myopic and has a prescription that dictates the use of -0.5 diopters of vision correction. In this situation, the vision correction component of lens 44 is -0.5. Combined with the negative bias component of -1.0 diopters, the lens power of inner lens 44 (in this example) is -1.5 diopters.

[0037] The display image coupled into the waveguide 50 is coupled from the waveguide 50 towards the eyebox 24 by the output coupler 56, as shown by light 48. The display image in light 48 passes through the negative bias of the inner lens 44, which places the display image at the desired virtual image distance, which is 1 meter in the exemplary situation where the negative bias of the lens 44 is -1 diopter. The vision correction component of the lens 44 (which in this example is -0.5 diopters for the illustrative user) is used to correct the myopia of the user. In general, the vision correction component of the lens 44 may be used to correct for hyperopia, myopia, astigmatism, etc.

[0038] The presence of a lens power in outer lens 42 that is equal and opposite to the negative bias component of lens 44 compensates for the presence of the negative bias lens power in inner lens 44 when the user is viewing a real-world object (e.g., world light emitted and / or reflected by a real-world object). This is because the +1 diopter bias of lens 42 and the −1.0 diopter bias of lens 44 cancel each other out, and therefore no lens power is imposed on the real-world image light passing through lens 42, waveguide 50, and lens 44 to the eyebox 24.

[0039] The optical systems for the user's left and right eyes (sometimes referred to as eyeglass lenses, optical combiner systems, etc.) may include optical component layers. For example, a fixed light absorbing layer (sometimes referred to as a fixed tint layer) may be formed from a polymer film containing dyes and / or pigments (by way of example). This type of tint layer may be attached on or adjacent to an inner or outer surface of lens 42 (by way of example) to help reduce the brightness of a real-world object such as object 40 (e.g., world light from object 40) so that the intensity of the real-world image light does not overwhelm the intensity of the image light from display module 20A used in generating virtual image 46 (e.g., in light 48 provided to eyebox 24).

[0040] If desired, the light absorbing layer(s) or other optical component(s) in device 10 may be adjustable. These adjustable optical components may include adjustable layers controlled by control signals from control circuitry 12. By way of example, the electrically adjustable tint layer (sometimes referred to as an electrically adjustable light modulator or an electrically adjustable light modulator layer) may be formed from an organic or inorganic electrochromic light modulator layer or a guest-host liquid crystal light modulator layer. The adjustable tint layer may be formed from a structure located between output coupler 56 and lens 42 and / or may be located on the exterior-facing side of lens 42. During operation of device 10, the electrically adjustable tint layer may be dynamically positioned in a high transmission mode (sometimes referred to herein as a clear state) when it is desired to improve the visibility of real-world objects, or in a low transmission mode (sometimes referred to herein as a dark state) when it is desired to reduce scene brightness, thereby helping to improve the visibility of image light from display module 20A (e.g., allowing virtual objects, such as virtual objects in virtual image 46, to be viewed without being overwhelmed by bright ambient light).

[0041] Other electrically adjustable optical components may also be provided in device 10 as desired. These components may include, for example, an electrically adjustable polarizer layer, such as an adjustable polarizer based on liquid crystals, an electrically adjustable light reflector, such as an adjustable cholesteric liquid crystal layer, an electrically adjustable color cast layer, such as a color cast adjustment layer based on guest-host liquid crystals, an adjustable haze layer based on a polymer dispersed liquid crystal layer, and / or other electrically adjustable optical layers. In an exemplary configuration, which may be described herein by way of example, the left and right eyeglass lenses of device 10 may comprise an adjustable tint layer (e.g., an adjustable light modulator layer, such as an electrochromic layer, a guest-host liquid crystal layer, or other layer configured to exhibit adjustable light transmission). The adjustable tint layer may be used in bright ambient light conditions to temporarily reduce the amount of real-world light from an object, such as object 40, that reaches eyebox 24. This reduces the scene brightness, thereby allowing the displayed image light from waveguide 50 to be seen in eyebox 24 without being overwhelmed by, and thereby washed out by, overly bright real-world image light.

[0042] The adjustable tint layer (or other fixed and / or adjustable optical layer) may be attached to the interior and / or exterior surfaces of some or all of the optical components, such as lens 44, lens 42, and / or waveguide 50. To reduce the weight and / or size of device 10, it may be desirable to form the adjustable tint component and / or other optical components using a transparent substrate structure (transparent layer) that forms part of lens 42, lens 44, and / or waveguide 50.

[0043] FIG. 3 is a side cross-sectional view showing an example of how an adjustable optical component, such as an adjustable tint layer, can be incorporated into optical system 20B. As shown in FIG. 3, optical system 20B may include a head-mounted support structure 70 (e.g., part of support structure 8 in FIG. 1) to house the components of system 10 and support system 10 on the user's head. Support structure 70 may include, for example, structures (sometimes referred to as frames, lens support frames, eyeglass frames, etc.) that form housing walls and other structures on the front of system 10. In particular, support structure 70 may include support structures on the front of device 10 that form eyeglass frame structures such as a nose bridge, frame portions that support left and right lenses with embedded waveguides, and / or other housing structures. Support structure 70 may also include additional structures such as eyeglass side frame structures such as straps, eyeglass arms (temples), or other auxiliary support structures that help hold the frame and components within the frame on the user's face so that the user's eyes are positioned within eyebox 24. If desired, the support structure 70 may include hinges (eg, so that the arms of the system 10 can be folded parallel to a frame at the front of the device 10 when not in use).

[0044] 3, the waveguide 50, one or more waveguide cover layers, such as cover layer 72 and cover layer 84 (e.g., cover glass layers), outer lens 42, and inner lens 44 may be attached to a support structure 70. Optionally, cover layer 72 may be separated from the waveguide 50 by an air gap 78 and / or cover layer 84 may be separated from the waveguide 50 by an air gap 76. The air gaps 78 and 76 may, for example, maintain total internal reflection of image light within the waveguide 50. Optionally, optical system 20B may include one or more peripheral adhesive seals (e.g., rings of adhesive) that seal the air gaps of optical system 20B from the external environment while the components of optical system 20B are attached to the support structure 70.

[0045] The waveguide 50 may include an output coupler 56. The output coupler 56 may couple image light (e.g., image light 38 in FIG. 2) propagating within the waveguide 50 out through the lens 44 toward the eyebox 24 (as light 48). The light 48 may also include light from a real-world object (e.g., object 40 in FIG. 2) in front of the system 10. In examples where the output coupler 56 includes one or more holograms (e.g., volume holograms), the waveguide 50 may include one or more waveguide substrates that sandwich a grating medium layer in which the holograms are recorded. In these examples, the cover layers 72 and / or 84 may be omitted, as desired. In examples where the output coupler 56 includes one or more surface relief gratings, the waveguide 50 may include a surface relief grating substrate. The surface relief grating may be formed (e.g., etched or cut) into one or both sides (e.g., the opposing lens 42 and / or the opposing lens 44) of the surface relief grating substrate. The cover layers 72 and 84 may serve to protect the microstructure of the surface relief grating from damage or contaminants, for example.

[0046] The optical system 20B can include an electrically adjustable optical component, such as an adjustable tint layer 82. The adjustable tint layer 82 can include one or more substrates and one or more layers of an electrically adjustable tint material (e.g., sandwiched between the substrates). The adjustable tint material can include, by way of example, an organic electrochromic (EC) material, an inorganic electrochromic material, or a guest-host liquid crystal layer. The adjustable tint layer 82 can include two or more electrodes formed from a transparent conductive layer (e.g., a layer of indium tin oxide (ITO) or other transparent conductive coating material). The electrodes can receive control signals from the control circuit 16 (FIG. 1).

[0047] The control circuitry can adjust the voltage of the control signal provided across the terminals of the electrodes to vary the electric field applied by the electrodes to the layer of tint material, thereby adjusting the amount of light transmission exhibited by the layer of tint material. In an exemplary configuration, the layer of tint material can exhibit a variable amount of light transmission that varies continuously between a minimum level TMIN and a maximum level TMAX. The value of TMIN can be 5%, 10%, 15%, 20%, 2-15%, 3-25%, 5-40%, 10-30%, 10-25%, at least 3%, at least 6%, at least 15%, at least 20%, less than 35%, less than 25%, less than 15%, or other suitable minimum level sufficient to help reduce environmental (real world) light while viewing computer-generated images from display module 20A in bright ambient light conditions (e.g., the dark state of adjustable tint layer 82). The value of TMAX may be at least 50%, at least 60%, 60-99%, 40-99.9%, 80-99%, 70-99%, 80-97%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, less than 99.99%, less than 99%, or any other suitable maximum level that is sufficiently transparent to allow a viewer to comfortably view real world objects through layer 82 during situations in which display module 20A is not providing an image or other situations in which a higher transmission level is desired (e.g., the clear state of adjustable tint layer 82). The layer of tint material may be referred to herein as blocking world light from passing to the output coupler when configured to exhibit a transmission level TMIN or any other desired transmission level less than TMAX.

[0048] 3, the adjustable tint layer 82 is attached to the lens 42 (e.g., the adjustable tint layer 82 may be laminated on the inner surface of the lens 42). The adjustable tint layer 82 may be separated from the cover layer 72 by an air gap 80. This is merely exemplary. In other configurations, the adjustable tint layer 82 may be laminated on the outer surface of the lens 42.

[0049] If desired, additional layer(s) of tint material may be disposed at one or more locations within optical system 20B (e.g., overlapping adjustable tint layer 82 and output coupler 56). As an example, additional fixed or electrically adjustable tint layers may be laminated onto the outer surface of lens 42. If desired, a removable tint layer, such as removable tint layer 85, may be attached to, adjacent to, or on the outer surface of lens 42 (e.g., in a position overlapping adjustable tint layer 82 and output coupler 56). Removable tint layer 85 may be an electrically adjustable tint layer (e.g., an adjustable tint layer, such as adjustable tint layer 82) or may be a fixed tint layer having fixed light transmission characteristics. Removable tint layer 85 may be attached, secured, glued, clipped, or otherwise secured to support structure 70 or other support structure of system 10. Removable tint layer 85 may be added, for example, by a user of system 10 who desires to add tinting capabilities to system 10. If desired, adjustable tint layer 82 may be omitted in scenarios where removable tint layer 85 is attachable to support structure 70. A user of system 10 may replace removable tint layer 85 with another removable tint layer having different tinting properties, or may simply remove tint layer 85 to remove the tinting properties of the tint layer from system 10. Removable tint layer 85 may be omitted if desired.

[0050] The example of Figure 3, in which the adjustable tint layer 82 is laminated directly onto the inner surface of the lens 42, is merely illustrative. If desired, the adjustable tint layer 82 may be interposed between the waveguide 50 and the lens 42, with an air gap interposed between the adjustable tint layer and the lens 42. Figure 4 is a side cross-sectional view showing one example of how the adjustable tint layer 82 may be disposed between the waveguide 50 and the lens 42, with an air gap interposed between the adjustable tint layer and the lens 42.

[0051] As shown in FIG. 4, the adjustable tint layer 82 may be attached to the support structure 70 between the lens 42 and the cover layer 72 (or the waveguide 50 in examples where the cover layer 72 is omitted). An air gap, such as air gap 86, may be interposed between the adjustable tint layer 82 and the lens 42 (e.g., so that the adjustable tint layer 82 does not contact the lens 42). So positioned, the air gap 80 remains interposed between the adjustable tint layer 82 and the cover layer 72. This example is merely illustrative. If desired, the adjustable tint layer 82 may be laminated directly onto the cover layer 72.

[0052] Figure 5 is a cross-sectional side view illustrating how the adjustable tint layer 82 may be laminated directly onto the cover layer 72. As shown in Figure 5, the air gap 80 (Figure 4) may be omitted and the adjustable tint layer 82 may be disposed or laminated onto the cover layer 72. When so disposed, an air gap 86 remains interposed between the adjustable tint layer 82 and the lens 42.

[0053] 4 and 5 in which cover layer 72 is interposed between lens 42 and waveguide 50 are merely illustrative. If desired, cover layer 72 may be omitted, as shown in the side cross-sectional view of FIG. 6. As shown in FIG. 6, adjustable tint layer 82 may be attached to support structure 70 at a location between lens 42 and waveguide 50 such that air gap 78 is interposed between waveguide 50 and adjustable tint layer 82, and air gap 86 is interposed between adjustable tint layer 82 and lens 42. If desired, adjustable tint layer 82 may help protect waveguide 50 from contaminants or damage in this configuration (e.g., optical system 20B exhibits a smaller overall thickness in the Y dimension as compared to examples in which cover layer 72 is included in optical system 20B).

[0054] To further reduce the thickness of optical system 20B, lens 42 and / or lens 44 may be formed from an adjustable tint material, as shown in the cross-sectional side view of FIG. 7 (e.g., lens 42 and / or lens 44 may itself be an adjustable tint layer, such as adjustable tint layer 82 of FIGS. 3-6). As shown in FIG. 7, lens 44 and / or lens 42 may be an adjustable tint lens (e.g., having one or more layers of adjustable tint material, such as inorganic or organic EC layers or guest-host liquid crystal layers, one or more transparent substrates, and two or more electrode layers). The electrode layer in lens 42 may receive a control signal from control circuit 16 (FIG. 1) via terminal 92 that adjusts the light transmission characteristics of lens 42. The electrode layer in lens 44 may receive a control signal from control circuit 16 (FIG. 1) via terminal 94 that adjusts the light transmission characteristics of lens 44.

[0055] The geometry of lens 44 can be configured to form a negative bias lens (e.g., to impart optical power to image light and world light), with lens 44 also providing adjustable tinting based on a control signal (voltage) provided via terminal 94. The geometry of lens 42 can be configured to form a positive bias lens (e.g., to impart optical power to world light), with lens 42 also providing adjustable tinting based on a control signal (voltage) provided via terminal 92. If desired, lens 42 can be an adjustable tint lens, but lens 44 does not provide fixed and / or adjustable tinting.

[0056] The examples of Figures 4-7 are merely illustrative. Cover layer 84 may be omitted if desired. As described in connection with Figure 3, one or more additional tint layers may be incorporated into the examples of Figures 4-7. For example, in the example of Figures 4-7, a removable adjustable tint layer 85 may be provided on optical system 20B.

[0057] Optionally, the adjustable tint layer 82 of FIGS. 3-6 (or the lenses 42 / 44 of FIG. 7) may be controlled / transitioned (e.g., using control signals / voltages provided by the control circuit 16 of FIG. 1) between a plurality of states, each having different light transmission characteristics. For example, the adjustable tint layer 82 of FIGS. 3-6 (or the lenses 42 / 44 of FIG. 7) may be switched between a clear state (e.g., when the user is viewing world light or when the ambient light level is relatively low) that maximizes the transmission of light through the adjustable tint layer, and a uniform dark state (e.g., when the user is viewing a display image light or when the ambient light level is relatively high) that minimizes the transmission of light through the adjustable tint layer. Optionally, the adjustable tint layer 82 of FIGS. 3-6 (or the lenses 42 / 44 of FIG. 7) may also be switched to a gradient dark state, where different portions of the field of view are provided with a gradient of tinting.

[0058] Figure 8 is a front view illustrating how adjustable tint layer 82 may transition between a clear state, a uniform dark state, and a gradient dark state. As shown in Figure 8, adjustable tint layer 82 may be provided with two or more electrodes, such as electrode 98, on either side of the adjustable tint layer. Although referred to as adjustable tint layer 82 in Figure 8, adjustable tint layer 82 in Figure 8 may include lens 42 and / or lens 44 of Figure 7.

[0059] The control circuit 16 (FIG. 1) can provide a control signal (voltage) across the electrodes 98 that places the adjustable tint layer 82 in a clear state. This can maximize light transmission across the field of view of the eyebox. The control circuit 16 can vary the voltage across the electrodes 98, as indicated by arrow 96, to place the adjustable tint layer 82 in a uniform dark state. This can minimize light transmission across the field of view of the eyebox.

[0060] The control circuitry 16 can control the electrodes 98 along a given axis (e.g., the Z-axis in FIG. 8 ) to place the adjustable tint layer 82 in a gradient dark state (sometimes referred to herein as a gradient state), as indicated by arrow 97. In the gradient dark state, the adjustable tint layer 82 can exhibit a gradient of light transmission (tint), such as a gradient from a first level at a first edge of the field of view to a second level at a second edge of the field of view. Gradient tint may be implemented by varying the thickness of the tint layer along the direction of the gradient, by varying the electrode resistance along the direction of the gradient, by providing multiple electrodes with different voltages along the direction of the gradient, etc. The gradient dark state may be used while the system 10 is located outside, for example, to help prevent sunlight from reaching the eyebox while still allowing the user to clearly see other real-world objects. The example of FIG. 8 in which the gradient extends along the Z-axis is merely illustrative, and in general, the gradient may be provided along any axis.

[0061] The example of FIG. 8 is merely illustrative, and if desired, the adjustable tint layer 82 may have fewer than three states (e.g., the uniform dark or gradient dark states may be omitted) or may have more than three states with different light transmission characteristics. In addition to (or instead of) adjusting the level of light transmission, the adjustable tint layer 82 may be controlled to impart a desired tint or hue to the light transmitted through the adjustable tint layer to the eyebox. If desired, the control circuitry may transition the adjustable tint layer to different states, with the adjustable tint layer imparting a different desired color profile or hue to the transmitted light in each state.

[0062] FIG. 9 is a side cross-sectional view illustrating an example of an adjustable tint layer 82 that can be placed in different states to impart different color profiles or hues to light transmitted to the eyebox. As shown in FIG. 9, the adjustable tint layer 82 (e.g., the adjustable tint layer 82 of FIGS. 3-6 or the lenses 42 / 44 of FIG. 7) may include multiple layers sandwiched between transparent substrates, such as substrates 100 and 124. For example, the adjustable tint layer 82 may include a first tint material layer 102 (e.g., a layer of inorganic EC material, a layer of organic EC material, or a guest-host liquid crystal layer) configured to transmit a first wavelength range or hue of incident light, such as a green hue, a second tint material layer 110 (e.g., a layer of inorganic EC material, a layer of organic EC material, or a guest-host liquid crystal layer) configured to transmit a second wavelength range or hue of incident light, such as a red hue, and a third tint material layer 118 (e.g., a layer of inorganic EC material, a layer of organic EC material, or a guest-host liquid crystal layer) configured to transmit a third wavelength range or hue of incident light, such as a blue hue. Thus, tint material layers 102, 110, and 118 may be referred to herein as green layer 102, red layer 110, and blue layer 118. However, this is merely an example, and in general layers 102, 110, and 118 may transmit light in any desired wavelength range.

[0063] The adjustable tint layer 82 may include a set of electrode layers, such as electrodes 106, 114, and 122. The adjustable tint layer 82 may include electrolyte layers, such as a first electrolyte layer 104 interposed between the green layer 102 and the electrode 122, a second electrolyte layer 112 interposed between the red layer 110 and the electrode 106, and a third electrolyte layer 120 interposed between the blue layer 118 and the electrode 114. If desired, the adjustable tint layer 82 may include additional transparent substrate layers, such as a substrate layer 108 interposed between the electrode 106 and the red layer 110, and a substrate layer 116 interposed between the electrode 114 and the blue layer 118. The electrodes 106, 114, and 122 may be, for example, counter electrodes.

[0064] The control circuitry 14 can provide control signals (voltages) to the electrodes 106, 114, and 122 to transition the adjustable tint layer 82 between different states in which the adjustable tint layer imparts different hues to the transmitted light. For example, the control circuitry can place the adjustable tint layer 82 in a uniform or gradient dark state in which the green layer 102, red layer 110, and blue layer 118 combine uniformly to prevent the transmission of visible light through the adjustable tint layer. The control circuitry can place the adjustable tint layer 82 in a clear state in which the green layer 102, red layer 110, and blue layer 118 combine to uniformly transmit all wavelengths of visible light through the adjustable tint layer. The control circuitry can place the adjustable tint layer 82 in a red state in which the red layer 110 imparts a red hue to the transmitted light while the green layer 102 and blue layer 118 are inactive, a blue state in which the blue layer 118 imparts a blue hue to the transmitted light while the red layer 110 and green layer 102 are inactive, a green state in which the green layer 102 imparts a green hue to the transmitted light while the red layer 110 and blue layer 118 are inactive, or other states that vary the amount of light transmission of the layers 102, 110, and 118 to impart different intensities to the transmitted light in any desired wavelength range(s).

[0065] The example of Figure 9 in which the adjustable tint layer 82 includes three color layers for adjusting the hue of the transmitted light is merely illustrative. If desired, the adjustable tint layer may include tandem color layers for adjusting the hue of the transmitted light, as shown in the examples of Figures 10 and 11. As shown in Figure 10, the adjustable tint layer 82 may include a first tint material layer (e.g., green layer 102), a second tint material layer (e.g., red layer 110), and an electrolyte layer 134 sandwiched between the first and second tint material layers, all sandwiched between substrates 100 and 124. As shown in FIG. 11, the tunable tint material layer 82 may include a first tint material layer 110 (e.g., red layer 110), an electrolyte layer 134, a second tint material layer (e.g., green layer 102) sandwiched between the red layer 110 and the electrolyte layer 134, and an electrode 136 (e.g., when the electrolyte layer 134 is sandwiched between the green layer 102 and the electrode 136), all sandwiched between the substrates 100 and 124.

[0066] The examples of Figures 9-11 are merely illustrative. The adjustable tint material layers of Figures 9-11 may be arranged in other orders. Each adjustable tint material layer (e.g., layers 102, 110, and 118) may be configured to transmit any desired wavelength range of light. The color tinting of Figures 9-11 may be combined with the gradient tinting of Figure 8, if desired. The adjustable tint layer 82 may include more than three layers of adjustable tint material, if desired. In examples where the optical system 20B includes multiple adjustable tint layers 82, each layer may include at least one individual adjustable tint layer that transmits an individual wavelength range (e.g., the functionality of the adjustable tint layer 82 of Figure 9 may be distributed across two or more adjustable tint layers 82 arranged at different locations of the optical system 20B).

[0067] FIG. 12 is a state diagram illustrating how the control circuit 16 (FIG. 1) can transition the adjustable tint layer 82 between different states, each having a distinct light transmission characteristic. As shown in FIG. 12, the adjustable tint layer 82 can have at least a clear state (mode) 140, a uniform dark state (mode) 142, a gradient dark state (mode) 144, and a set of N color states 146 (e.g., a first color state 146-1, a second color state 146-2, etc.). If desired, one or more of the color states may be operated in a gradient mode. The arrows in FIG. 12 indicate the potential transitions between the states. The control circuit 16 can adjust the control signals provided to electrodes on the adjustable tint layer 82 to transition the adjustable tint layer 82 between the different states.

[0068] In the clear state 140, the adjustable tint layer 82 can transmit as much light as possible uniformly across the wavelength range of the adjustable tint material layer (e.g., to allow a user to clearly see real world objects). In the uniform dark state 142, the adjustable tint layer 82 can block as much light as possible uniformly across the wavelength range of the adjustable tint material layer (e.g., to allow a user to clearly see virtual objects in image light). In the gradient dark state 144, the adjustable tint layer 82 can transmit light having a gradient of darkness / brightness across the field of view (e.g., as described in connection with FIG. 8).

[0069] In each color state 146, the control circuitry 16 can configure each of the adjustable tint material layers (e.g., layers 102, 110, and 118 of FIGS. 9-11) in the adjustable tint layer 82 to impart a desired range of wavelengths (hues) to the light transmitted by the adjustable tint layer 82 (e.g., by transmitting different amounts of light at different wavelengths). For example, in a first color state 146-1, the adjustable tint layer 82 can transmit more blue light than the other colors (e.g., using the blue layer 118 of FIG. 9) to impart a blue hue to the transmitted light, and in a second color state 146-2, the adjustable tint layer 82 can transmit more red light than the other colors (e.g., using the red layer 110 of FIGS. 9-11) to impart a red hue to the transmitted light. Control circuitry 16 may switch between different colors based on the color temperature of the ambient light (e.g., to provide the user with a particular hue of real-world light) or based on user input (e.g., when the user wants to use system 10 with a sunglasses function of a particular hue).

[0070] Optionally, one or more of the color states 146 may configure the adjustable tint layer 82 to correct for one or more different types of user color blindness, thereby enabling the system 10 to display color images that are appropriately perceived by different users having different color blindness characteristics.

[0071] FIG. 13 includes plots showing how different color states can be used to mitigate different types of color blindness. Plot 160 plots the eye response of a user with a first type of color blindness, and plot 162 plots the eye response of a user with a second type of color blindness. Curve 150 plots the user's S-cone response, curve 152 plots the user's M-cone response, and curve 154 plots the user's L-cone response. A user with the first type of color blindness may have an overlap between curves 152 and 154 in region R1 of plot 160 (e.g., causing the user to confuse red light with green light in region R1). To mitigate this type of color blindness, the adjustable tint layer 82 may be placed in a color state 146 that filters out wavelengths of light in region R1, thereby allowing the user with the first type of color blindness to properly see light from the display and the world.

[0072] A user with a second type of color blindness may have an overlap between curves 152 and 154 in region R2 of plot 160 that is different from region R1 (e.g., causing the user to confuse red and green light in region R2). To mitigate this type of color blindness, adjustable tint layer 82 may be placed in a color state 146 that filters out wavelengths of light in region R2, thereby allowing a user with a second type of color blindness to properly view light from the display and the world. Light transmitted by two or more of the adjustable tint material layers (e.g., EC layers) of adjustable tint layer 82 may be mixed in a first predetermined ratio to filter light in region R1 in the first color state 146 and mixed in a second predetermined ratio to filter light in region R2 in the second color state 146. Additionally or alternatively, separate adjustable tint material layers of different colors may be activated on demand.

[0073] In this manner, the adjustable tint layer 82 can mitigate color blindness across a wide range of users with different cone overlap characteristics. The EC color filter wavelength ranges can be individually adjusted, for example, by varying the tint % of each individual tint material layer. The filtering strength may be adjusted by an EC switching process or turned off completely as desired. The embodiment of FIG. 13 is merely illustrative. The adjustable tint layer 82 may be controlled to filter out any desired wavelength range to mitigate color blindness.

[0074] FIG. 14 is a side cross-sectional view illustrating how the adjustable tint layer 82 (or the lens 42 / 44 of FIG. 7) can be switched between states (e.g., the states of FIG. 12) using a DC voltage. As shown in FIG. 14, the adjustable tint layer 82 can include electrode layers, such as an ITO layer 172 on the substrate 100 and an ITO layer 180 on the substrate 124. The layers of tint material in the adjustable tint layer 82 can include an anode EC layer 174, an ion conductor (IC) layer 176, and a cathode EC layer 178. The anode EC layer 174 can be stacked on the ITO layer 172. The cathode EC layer 178 can be stacked on the ITO layer 180. The IC layer 176 can be sandwiched between the cathode EC layer 178 and the anode EC layer 174. A DC voltage 170 (e.g., a control signal provided by the control circuit 16 of FIG. 1) can be applied across the ITO layers 172 and 180. DC voltage 170 can be adjusted to switch adjustable tint layer 82 between different states. The example of Figure 14 in which adjustable tint layer 82 includes a single layer of adjustable tint material is merely illustrative; if desired, adjustable tint layer 82 may include multiple layers of adjustable tint material to control the transmission of different wavelength ranges (e.g., as shown in Figures 9-11).

[0075] In general, electrochromic devices such as the adjustable tint layer 82 exhibit faster switching speeds at higher operating temperatures. The adjustable tint layer 82 may be heated to increase the switching speed of the adjustable tint layer. An external heater may be used to heat the adjustable tint layer 82, but the external heater may increase implementation costs and may cause excessive power consumption. To mitigate these issues, the adjustable tint layer 82 may include structures that allow the adjustable tint layer 82 to heat itself (e.g., the adjustable tint layer 82 may be self-heating). For example, an AC voltage may be applied to the adjustable tint layer 82 to cause resistive heating in the adjustable tint layer to maximize switching speed. The AC voltage may heat the adjustable tint layer independently of the switching performed by the DC voltage 170.

[0076] 15 is a front view of the adjustable tint layer 82 (e.g., taken in the direction of arrow 181 in FIG. 14 ) illustrating one example of how an AC voltage may be applied to the adjustable tint layer 82. As shown in FIG. 15 , a set of conductive contacts 186, such as first contact 186-1 and second contact 186-2, may be disposed only around the periphery of the ITO layer 184 (e.g., ITO layer 172 and / or ITO layer 180 in FIG. 14 ) in the adjustable tint layer 82. The contacts 186-1 and 186-2 may be disposed on either side of the ITO layer 184. As an example, the contacts 186 may include copper pads or other contact pads.

[0077] Contacts 186-1 and 186-2 can receive an AC voltage from control circuit 16 (FIG. 1). For example, contact 186-1 can receive an AC voltage V AC and contact 186-2 can receive a reverse AC voltage -V AC4. This AC voltage may create resistive heating across the ITO layer 184 without affecting the DC voltage used to switch the state of the adjustable tint layer 82. The resistive heating may maximize the switching speed of the adjustable tint layer 82. Additionally or alternatively, the AC voltage may be used to heat the adjustable tint layer 82 to perform defogging of the optical system 20B (e.g., to remove haze that has built up on the waveguide 50, the lens 42, the lens 44, etc.).

[0078] To further increase the uniformity with which the ITO layer 184 is heated across its surface area, multiple AC voltages can be driven across the ITO layer 184, as shown in the front view of FIG. 16. As shown in FIG. 16, the tunable tint layer 82 can include three or more contacts 182, such as contacts 182-1 through 182-6. Contact 182-5 can be positioned opposite contact 182-2 across a diameter of the ITO layer 184. Contact 182-1 can be positioned opposite contact 182-6 across a distance less than the diameter of the ITO layer 184. Contact 182-4 can be positioned opposite contact 182-3 across a distance less than the diameter of the ITO layer 184.

[0079] In this example, contact 182-5 is located farther from contact 182-2 than contact 182-6 is from contact 182-1 and contact 182-4 is from contact 182-3. Thus, ITO layer 184 may exhibit a greater resistance between contacts 182-5 and 182-2 than between contacts 182-6 and 182-1 and between contacts 182-4 and 182-3. To mitigate this variation in resistance, the first AC voltage V H may be applied between contacts 182-5 and 182-2, while an AC voltage V H A second AC voltage V having a magnitude lower than Lis applied between contacts 182-6 and 182-1 and between contacts 182-4 and 182-3. The increased AC voltage applied across the diameter of the ITO layer 184 may mitigate the increased resistance between contact pads 182-5 and 182-2 relative to the resistance between contacts 182-6 and 182-1 and between contacts 182-4 and 182-3. This may allow a uniform amount of resistive heating to be performed across the surface area of ​​the ITO layer 184. This uniform heating may, for example, help maximize switching speeds across the entire field of view and / or allow for a uniform defogging pattern to be applied across the entire field of view. The applied AC voltage does not affect the DC voltage 170 (FIG. 14) used to switch the tunable tint layer 82. The example of FIG. 16 is merely illustrative, and in general there may be any desired number of contacts 182 on the ITO layer 184 to receive one or more AC voltages.

[0080] If desired, the adjustable tint layer 82 may be configured to form a self-switching EC device. Although described herein with respect to the adjustable tint layer 82, the lenses 42 / 44 of FIG. 7 may similarly be configured to form a self-switching EC device. The self-switching EC device may have an automatic switching capability (e.g., to automatically switch between two or more of the states of FIG. 12) under sunlight. When configured as a self-switching electrochromic device, the adjustable tint layer 82 may integrate and utilize a transparent solar cell that forms an internal power source for the adjustable tint layer. This allows the adjustable tint layer 82 to be powered without an external power source (e.g., control circuit 16) instead of using sunlight to power the switches between states.

[0081] FIG. 17 is a side cross-sectional view showing one example of how the tunable tint layer 82 of FIGS. 3-6, 8-11, and 14-16 (or the lenses 42 / 44 of FIG. 7) may be configured to form a self-switching EC device. As shown in FIG. 17, a first anti-reflection (AR) coating 210 may be deposited on a first surface of the substrate 100. A second AR coating 212 may be deposited on a second surface of the substrate 100. A third AR coating 226 may be deposited on a first surface of the substrate 124. A fourth AR coating 228 may be deposited on a second surface of the substrate 124. One or more of these AR coatings may be omitted, if desired.

[0082] A transparent electrode layer, such as an ITO layer 214, may be deposited on the AR coating 214. An n-type ultraviolet (UV) / near infrared (NIR) active layer 216 may be deposited on the ITO layer 214. A p-type UV / NIR active layer 218 may be deposited on the n-type UV / NIR active layer 216. An additional transparent electrode layer, such as an ITO layer 220, may be deposited on the p-type UV / NIR active layer 218. A tunable tint material layer having an anode EC layer 174, an IC layer 176, and a cathode EC layer 178 may be deposited on the ITO layer 220. A third transparent electrode layer, such as an ITO layer 222, may be deposited on the cathode EC layer 178. A UV / NIR reflector layer 224 may be deposited on the ITO layer 222. An AR coating 224 may be deposited on the UV / NIR reflector layer 224. A switch, such as switch 208, may be coupled (e.g., using external wiring) between ITO layer 214 and ITO layer 222. This example is merely illustrative, and additional or fewer layers may be stacked in adjustable tint layer 82, as desired. The layers of adjustable tint layer 82 may also be stacked in other orders, as desired. The layers in adjustable tint layer 82 may also be referred to herein as coatings, films, or thin films.

[0083] In general, electrochromic (EC) materials can change their optical properties with an electric potential (voltage). This allows light to be modulated by an electric field. Under natural conditions, each film (layer) of the tunable tint layer 82 exhibits low absorption in visible light, making the tunable tint layer 82 appear transparent. However, when an external electric potential is applied, positive lithium (Li) ions flow from the anode EC layer to the cathode EC layer. The IC layer 176 blocks direct electron transfer from the anode EC layer to the cathode EC layer, so electrons flow from one electrode to the other through an external conduction path. Because the anode EC material strongly absorbs in the visible range when it loses positive Li ions (while the cathode EC material strongly absorbs in visible wavelengths when it binds positive Li ions), the entire device becomes dark in visible light under an electric potential.

[0084] However, such EC devices often require an external power source (e.g., a power source in control circuit 16 of FIG. 1) to perform the light modulation. Such an external power source can increase implementation costs and / or power consumption and reduce the battery life of system 10. The switching speed of the EC device can impose another limitation. Generally, the switching speed doubles for every 10° C. increase in device temperature. However, adding an external heating source can also increase implementation costs and / or power consumption. To alleviate these issues, tunable tint layer 82 can function as a self-switching EC device.

[0085] As shown in FIG. 17, a transparent solar cell is formed from an n-type UV / NIR active layer 216, a p-type UV / NIR active layer 218, and an ITO layer 220 in a tunable tint layer 82, which forms a common transparent conductor between the transparent solar cell and the tunable tint material layer formed from an anode EC layer 174, an IC layer 176, and a cathode EC layer 178. The n-type UV / NIR active layer 216 and the p-type UV / NIR active layer 218 absorb light at UV and NIR wavelengths to generate electrons and holes. The AR coating layers 210, 212, 226, and 228 can minimize light reflection, thereby maximizing the optical performance of the EC device in both clear and dark states. The UV / NIR reflector layer 224 can reflect UV and NIR light to increase the efficiency of the solar cell formed from the layers 216-220. Substrates 100 and 124 may be transparent encapsulating substrates that minimize the effect of moisture on the tunable tint layer, thereby maximizing reliability. IC layer 176 may function to block the direct transfer of electrons from anode EC layer 174 to cathode EC layer 178, while also allowing positive ions to pass during the switching process.

[0086] Sunlight 200 may be incident on the tunable tint layer 82. The sunlight 200 may include visible light 202 at visible wavelengths, UV light 204 at UV wavelengths, and NIR light 206 at NIR wavelengths. The sunlight 200 may pass through the layers of the tunable tint layer 82, as indicated by arrow 230. The UV / NIR reflector layer 224 may reflect the UV light 204 and the NIR light 206, as indicated by arrow 232, thereby optimizing the efficiency of the solar cells within the tunable tint layer 82.

[0087] In the clear state, the switch 208 is open, inactive, or turned off (e.g., an open circuit or infinite impedance is inserted on the external conductive path between the ITO layers 214 and 222). When the switch 208 is open, the visible light 202 can pass through the EC device and thus through the tunable tint layer 82, as indicated by the arrow 234. However, the UV light 204 and the NIR light 206 can be absorbed in the n-type UV / NIR active layer 216 and the p-type UV / NIR active layer 218. While the switch 208 is open, the positive Li ions in the anode EC layer 174 cannot pass through the IC layer 176 because there is no external current path between the ITO layers 214 and 222. Both the anode EC layer 174 and the cathode EC layer 178 remain transparent to the visible spectrum. The absorption of the UV / NIR light in the layers 216 and 218 can be dissipated as heat. This may allow the entire device to isolate heat from one side of the tunable tint layer to the other. Additionally, heat dissipation in layers 216 and 218 helps to heat layers 174, 176, and 178, thereby maximizing the switching speed of tunable tint layer 82.

[0088] In the dark state, switch 208 is closed, active, or turned on (e.g., a closed circuit or zero impedance is inserted on the external conductive path between ITO layers 214 and 222). When switch 208 is closed, visible light 202 cannot pass through the EC devices, such as layers 174-178. UV light 204 and NIR light 206 are absorbed in layers 216 and 218, generating electrons and holes. In this case, a direct current path exists between ITO layers 214 and 222 through switch 208, so that the positive Li ions (Li + The generated electrons (e -) passes from layer 216 / 218 to ITO layer 214, as shown by arrow 242, through switch 208 to ITO layer 222, as shown by arrow 236. At the same time, generated holes pass from layer 216 / 218 to ITO layer 220, as shown by arrow 240. Both anode EC layer 174 and cathode EC layer 178 become strongly absorbing of visible light 202 in this configuration, preventing the visible light from passing through tunable tint layer 82. In this way, tunable tint layer 82 can function similarly to a solar cell that uses sunlight to generate electrons and holes that charge the tunable tint layer to switch itself to a dark state and block visible light transmission when desired. This can make it possible, for example, to switch tunable tint layer 82 without using an external power source.

[0089] According to one embodiment, an electronic device is provided, the electronic device comprising: a projector configured to generate a first light; a waveguide configured to propagate the first light via total internal reflection; an output coupler configured to couple the first light from the waveguide and configured to transmit a second light from a scene; a bias lens configured to impart optical power to the second light; and an electrically tunable light modulator between the bias lens and the waveguide and configured to transmit the second light from the bias lens to the output coupler, the electrically tunable light modulator being separated from the bias lens by an air gap.

[0090] According to another embodiment, the electrically tunable light modulator includes a tunable tint layer.

[0091] According to another embodiment, the tunable tint layer comprises a layer selected from the group consisting of an organic electrochromic layer, an inorganic electrochromic layer, and a guest-host liquid crystal layer.

[0092] According to another embodiment, an electronic device includes a cover layer interposed between the waveguide and the electrically tunable optical modulator, the cover layer being separated from the waveguide by a first additional air gap and from the electrically tunable optical modulator by a second additional air gap.

[0093] According to another embodiment, the electronic device includes a cover layer interposed between the waveguide and the electrically tunable optical modulator, the cover layer being separated from the waveguide by an additional air gap, and the electrically tunable optical modulator being laminated onto the cover layer.

[0094] According to another embodiment, an additional air gap separates the electrically tunable optical modulator from the waveguide.

[0095] According to another embodiment, the electronic device includes an additional electrically tunable light modulator configured to transmit a second light, and the bias lens is inserted between the electrically tunable light modulator and the additional electrically tunable light modulator.

[0096] According to another embodiment, the bias lens includes an additional electrically tunable light modulator.

[0097] According to another embodiment, the electrically tunable light modulator is tunable between a clear state, a uniform dark state, and a gradient dark state.

[0098] According to another embodiment, the electrically tunable light modulator is tunable between a first state in which the electrically tunable light modulator imparts a first tint to the second light and a second state in which the electrically tunable light modulator imparts a second tint to the second light, the second tint being different from the first tint.

[0099] According to another embodiment, the first tint is configured to mitigate a first type of color blindness and the second tint is configured to mitigate a second type of color blindness different from the first type of color blindness.

[0100] According to another embodiment, the electrically tunable light modulator includes at least two contact pads configured to receive one or more alternating voltages that resistively heat the electrically tunable light modulator.

[0101] According to another embodiment, the electrically tunable light modulator includes a self-switching electrochromic device.

[0102] According to another embodiment, the self-switching electrochromic device includes a transparent solar cell.

[0103] According to one embodiment, an electronic device is provided, the electronic device comprising: a projector configured to generate a first light; a waveguide configured to propagate the first light via total internal reflection; a waveguide configured to couple the first light from the waveguide and configured to transmit a second light from a scene; and a bias lens configured to impart optical power to the second light, the bias lens including at least an electrically tunable optical modulator switchable between a first state in which the bias lens transmits the second light to the output coupler and a second state in which the bias lens blocks the second light from passing to the output coupler.

[0104] According to another embodiment, the electronic device includes an additional bias lens configured to at least partially reverse the optical power imparted to the second light by the bias lens, and the waveguide is interposed between the bias lens and the additional bias lens.

[0105] According to another embodiment, the additional bias lens includes an additional electrically tunable light modulator.

[0106] According to another embodiment, the electrically tunable light modulator has a third state in which the bias lens transmits a second light having the first hue and a fourth state in which the bias lens transmits a second light having a second hue different from the first hue.

[0107] According to another embodiment, an electrically tunable light modulator includes a first layer of electrochromic material and a second layer of electrochromic material different from the first layer of electrochromic material.

[0108] According to one embodiment, a display is provided, comprising: a projector configured to generate a first light; a waveguide configured to propagate the first light via total internal reflection; an output coupler configured to couple the first light from the waveguide and configured to transmit a second light from outside the display; and an electrically tunable light modulator that is adjustable between a first state and a second state using a direct current (DC) voltage, where in the first state the electrically tunable light modulator is configured to transmit the second light to the output coupler and in the second state the electrically tunable light modulator is configured to block the second light from passing to the output coupler, the electrically tunable light modulator including an indium tin oxide (ITO) layer having contacts configured to receive an alternating current (AC) voltage that resistively heats the electrically tunable light modulator.

[0109] According to another embodiment, the AC voltage has a first magnitude and the ITO layer has an additional contact configured to receive an additional AC voltage having a second magnitude less than the first magnitude.

[0110] According to one embodiment, there is provided a display comprising: a projector configured to generate a first light; a waveguide configured to propagate the first light via total internal reflection; an output coupler configured to couple the first light from the waveguide and configured to transmit a second light from outside the display; and a self-switching electrochromic device configured to transmit the second light to the output coupler.

[0111] According to another embodiment, the self-switching electrochromic device has a plurality of states, and the self-switching electrochromic device is configured to transmit a different, respective amount of the second light to the output coupler in each of the plurality of states.

[0112] According to another embodiment, the self-switching electrochromic device includes a transparent solar cell.

[0113] According to another embodiment, the self-switching electrochromic device includes an anodic electrochromic layer, an ion conductor layer, and a cathodic electrochromic layer, and the transparent solar cell includes an indium tin oxide (ITO) layer on the anodic electrochromic layer.

[0114] According to another embodiment, a transparent solar cell includes an n-type active layer and a p-type active layer.

[0115] According to another embodiment, a self-switching electrochromic device includes a first additional ITO layer on a transparent solar cell, a second ITO layer on a cathodic electrochromic layer, and a switch coupling the first additional ITO layer to the second additional ITO layer.

[0116] According to another embodiment, the display includes an ultraviolet and near infrared reflector layer on the second additional ITO layer.

[0117] The above is merely illustrative and various modifications may be made to the described embodiments. The above embodiments may be implemented individually or in any combination.

Claims

1. 1. An electronic device comprising: a projector configured to generate a first light; a waveguide configured to propagate the first light via total internal reflection; an output coupler configured to couple the first light from the waveguide and configured to transmit a second light from a scene; a bias lens configured to provide an optical power to the second light; an electrically tunable optical modulator between the bias lens and the waveguide and configured to transmit the second light from the bias lens to the output coupler, the electrically tunable optical modulator being separated from the bias lens by an air gap; An electronic device comprising:

2. The electronic device of claim 1 , wherein the electrically tunable light modulator comprises a tunable tint layer.

3. 3. The electronic device of claim 2, wherein the tunable tint layer comprises a layer selected from the group consisting of an organic electrochromic layer, an inorganic electrochromic layer, and a guest-host liquid crystal layer.

4. a cover layer interposed between the waveguide and the electrically tunable optical modulator, the cover layer being separated from the waveguide by a first additional air gap and from the electrically tunable optical modulator by a second additional air gap; The electronic device of claim 1 further comprising:

5. a cover layer interposed between the waveguide and the electrically tunable optical modulator, the cover layer being separated from the waveguide by an additional air gap, the electrically tunable optical modulator being laminated on the cover layer; The electronic device of claim 1 further comprising:

6. The electronic device of claim 1 , wherein an additional air gap separates the electrically tunable optical modulator from the waveguide.

7. and an additional electrically tunable light modulator configured to transmit the second light, the bias lens being interposed between the electrically tunable light modulator and the additional electrically tunable light modulator. The electronic device of claim 1 .

8. The electronic device of claim 1 , wherein the bias lens comprises an additional electrically tunable light modulator.

9. The electronic device of claim 1 , wherein the electrically tunable light modulator is tunable between a clear state, a uniform dark state, and a gradient dark state.

10. 2. The electronic device of claim 1, wherein the electrically tunable light modulator is tunable between a first state in which the electrically tunable light modulator imparts a first color shade to the second light and a second state in which the electrically tunable light modulator imparts a second color shade to the second light, the second color shade being different from the first color shade.

11. 11. The electronic device of claim 10, wherein the first tint is configured to mitigate a first type of color blindness and the second tint is configured to mitigate a second type of color blindness different from the first type of color blindness.

12. 10. The electronic device of claim 1, wherein the electrically tunable light modulator includes at least two contact pads configured to receive one or more alternating voltages that resistively heat the electrically tunable light modulator.

13. The electronic device of claim 1 , wherein the electrically tunable light modulator comprises a self-switching electrochromic device.

14. The electronic device of claim 13 , wherein the self-switching electrochromic device comprises a transparent solar cell.

15. 1. An electronic device comprising: a projector configured to generate a first light; a waveguide configured to propagate the first light via total internal reflection; an output coupler configured to couple the first light from the waveguide and configured to transmit a second light from a scene; 11. The electronic device of claim 10, further comprising: a bias lens configured to impart optical power to the second light, the bias lens including at least an electrically tunable optical modulator switchable between a first state in which the bias lens transmits the second light to the output coupler and a second state in which the bias lens blocks the second light from passing to the output coupler.

16. and an additional bias lens configured to at least partially reverse the optical power imparted to the second light by the bias lens, the waveguide being interposed between the bias lens and the additional bias lens.

16. The electronic device of claim 15.

17. The electronic device of claim 16 , wherein the additional bias lens comprises an additional electrically tunable light modulator.

18. 16. The electronic device of claim 15, wherein the electrically tunable light modulator has a third state in which the bias lens transmits the second light having a first hue and a fourth state in which the bias lens transmits the second light having a second hue different from the first hue.

19. 20. The electronic device of claim 18, wherein the electrically tunable light modulator comprises a first layer of electrochromic material and a second layer of electrochromic material different from the first layer of electrochromic material.

20. A display, a projector configured to generate a first light; a waveguide configured to propagate the first light via total internal reflection; an output coupler configured to couple the first light from the waveguide and configured to transmit a second light from outside the display; an electrically tunable optical modulator tunable between a first state and a second state using a direct current (DC) voltage, wherein in the first state, the electrically tunable optical modulator is configured to transmit the second light to the output coupler, and in the second state, the electrically tunable optical modulator is configured to block the second light from passing to the output coupler, the electrically tunable optical modulator comprising: A display comprising an indium tin oxide (ITO) layer having contacts configured to receive an alternating current (AC) voltage that resistively heats the electrically tunable light modulator.

21. 21. The display of claim 20, wherein the AC voltage has a first magnitude and the ITO layer has an additional contact configured to receive an additional AC voltage having a second magnitude less than the first magnitude.

22. A display, a projector configured to generate a first light; a waveguide configured to propagate the first light via total internal reflection; an output coupler configured to couple the first light from the waveguide and configured to transmit a second light from outside the display; a self-switching electrochromic device configured to transmit the second light to the output coupler.

23. 23. The display of claim 22, wherein the self-switching electrochromic device has a plurality of states, the self-switching electrochromic device being configured to transmit a different respective amount of the second light to the output coupler in each of the plurality of states.

24. 23. The display of claim 22, wherein the self-switching electrochromic device comprises a transparent solar cell.

25. 25. The display of claim 24, wherein the self-switching electrochromic device comprises an anodic electrochromic layer, an ion conductor layer, and a cathodic electrochromic layer, and the transparent solar cell comprises an indium tin oxide (ITO) layer on the anodic electrochromic layer.

26. 26. The display of claim 25, wherein the transparent solar cell further comprises an n-type active layer and a p-type active layer.

27. The self-switching electrochromic device comprises: a first additional ITO layer on the transparent solar cell; a second ITO layer on the cathodic electrochromic layer; and 27. The display of claim 26, further comprising: a switch coupling the first additional ITO layer to the second additional ITO layer.

28. 30. The display of claim 27 further comprising an ultraviolet and near infrared reflector layer on said second additional ITO layer.

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