Fast electroactive lens switching systems and methods

Abstract

To solve the following problem that conventional liquid crystal lenses switch on and off so slowly that a person can perceive the lenses' gradual transition from high to low refractive power, which makes it unsuitable for focusing virtual images quickly in an augmented, mixed, or virtual reality system.SOLUTION: A fast-switching electroactive lens system can switch so fast (e.g., in 35 milliseconds or less) that a person perceives its refractive power to change instantaneously. The system accomplishes this fast switching by using an electroactive wave plate in series with slower liquid-crystal lenses. The position of the wave plate can be switched quickly between emitting vertically or horizontally polarized light. Each lens focuses either vertically or horizontally polarized light and transmits orthogonally polarized light. By switching between polarization states, the wave plate effectively turns one lens on and the other lens off much faster than either lens could be switched by itself.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. § 119(e) to U.S. Patent Application No. 62 / 954,743, filed December 30, 2019, which is incorporated herein by reference in its entirety. [Background technology]

[0002] Electro-active lenses can be used to adjust the focus of a person's eyes on digital images presented on an augmented or virtual reality display at a fixed virtual position from the eye, but at various simulated distances. Typical electro-active lenses have small mass and volume and consume little energy, but they do not switch refractive powers quickly. A typical 30-40 mm wide electro-active lens takes hundreds of milliseconds to switch from one refractive power to another. This delay is noticeable to the user and reduces the quality of the visual experience. Summary of the Invention

[0003] The electro-active lens system of the invention can (appears to) be able to switch from one refractive power to another in tens of milliseconds, rather than hundreds of milliseconds. It does so using a pair of electro-active lens elements (also called electro-active lenses) configured to operate on light of orthogonal polarization states (e.g., horizontal and vertical polarization states) and a dynamic polarization switcher that can switch light between those orthogonal polarization states in tens of milliseconds. For example, a first electro-active lens element may be configured to focus horizontally polarized light but not vertically polarized light, and a second electro-active lens element may be configured to focus vertically polarized light but not horizontally polarized light. Even if the electro-active lens elements are turned on and off slowly, e.g., on the order of hundreds of milliseconds, the polarization adjuster can switch light between horizontal and vertical polarization states in tens of milliseconds. If the first and second electro-active lens elements have different refractive powers, the polarization adjuster can effectively change the refractive power of the lens within tens of milliseconds by rapidly switching light between horizontal and vertical polarization states.

[0004] While optical powers should be switched within tens of milliseconds or less, the time between switching events is rarely that short. In practice, the time between switching events can be several seconds or longer. The difference between the time it takes to switch electro-active lenses and the time between switching events can be exploited to increase switching speed in a device with a fast polarization adjuster (also called a polarization orientation changer or variable retarder) and one or more slower focus-changing devices (electro-active or liquid crystal lens elements). By combining a fast polarization-changing component with one or more slower focus-changing components (e.g., first and second electro-active lens elements), the polarization-changing component allows the optical power of only one focus-changing component to be "optically present" in the optical system at a time. One focus-changing component is optically present while the other focus-changing component is not, and vice versa. Because the polarization-changing component can quickly switch incident light from one polarization orientation to another, the system can quickly switch from one focus-changing component to another without moving parts. In a fast-changing electro-active lens system with only a single focus-changing element, the system can be quickly switched from a "lens on" state to a "lens off" state. There is no limit to the number of focus-changing elements that can be used in a single electro-active lens system.

[0005] The electro-active lens system of the invention comprises a polarization modifier, a first The optical system may include an electro-active lens and a second electro-active lens in optical communication with the polarization changer and the first electro-active lens. The polarization changer is switchable between a first state in which the polarization changer switches the polarization of light between a first polarization state and a second polarization state (e.g., orthogonal linear polarization states) and a second state in which the polarization changer transmits light in the first polarization state. The first electro-active lens is switchable between a first focusing state in which the first electro-active lens focuses light in the first polarization state and transmits light in the second polarization state and a first transmitting state in which the first electro-active lens transmits light in both the first and second polarization states. The second electro-active lens is switchable between a second focusing state in which the second electro-active lens focuses light in the first polarization state and transmits light in the second polarization state and a second transmitting state in which the second electro-active lens transmits light in both the first and second polarization states.

[0006] The polarization switch may include a liquid crystal waveplate and may have a phase difference of π / 2 in the first state and a phase difference of 0 in the second state. The polarization switcher may be configured to switch between the first and second states (i) faster than the first electro-active lens is configured to switch between the first focusing state and the first defocusing state, and (ii) faster than the second electro-active lens is configured to switch between the second focusing state and the second defocusing state. For example, the polarization switcher may switch between the first and second states within 100 milliseconds, 50 milliseconds, 35 milliseconds, 30 milliseconds, 25 milliseconds, 20 milliseconds, 15 milliseconds, 10 milliseconds, 5 milliseconds, or faster. Similarly, the first and second electro-active lenses may each be configured to switch between their respective focusing and defocusing states in more than 100 milliseconds.

[0007] The polarization switcher and the electro-active lens may be integrated together, for example, without an air gap between the components. For example, the polarization switcher and the first electro-active lens can share a first common substrate. Similarly, the first and second electro-active lenses can share a second common substrate.

[0008] The electro-active lens system may be used or operated by setting the polarization switcher to a first or second state, setting the first electro-active lens to a first focusing state or a first defocusing state, setting the second electro-active lens to a second focusing state or a second defocusing state, and transmitting light through the polarization switcher, the first electro-active lens, and the second electro-active lens. When the polarization switcher is in the first state, the first electro-active lens is in the first focusing state, and the second electro-active lens is in the second defocusing state, the second electro-active lens can be switched from the second defocusing state to the second focusing state, during which the system transmits light in the first polarization state through the polarization switcher, focuses the light with the first electro-active lens, and transmits light through the second electro-active lens without focusing the light with the second electro-active lens. After the second electro-active lens is switched from the second non-focusing state to the second focusing state, the polarization switcher can be switched from the first state to the second state, thereby focusing light on the second electro-active lens and transmitting light without focusing light on the first electro-active lens. The switching of the second electro-active lens from the second non-focusing state to the second focusing state and the switching of the polarization switcher from the first state to the second state can occur in response to a desired change in the position of the virtual image. The switching of the second electro-active lens from the second non-focusing state to the second focusing state can take at least 100 milliseconds, and the switching of the polarization switcher from the first state to the second state can take less than 100 milliseconds.

[0009] Another electro-active lens system includes a liquid crystal waveplate in an optical system with first and second liquid crystal lenses. The liquid crystal waveplate is switchable between a zero-wave retardation and a half-wave retardation within 35 milliseconds. The first liquid crystal lens is switchable between a first state that focuses light of a first linear polarization state onto a first focal plane and a second state that focuses light of the first linear polarization state onto a second focal plane. The second liquid crystal lens focuses light of a second linear polarization state orthogonal to the first linear polarization state. The optical element is switchable between a first state that focuses light of the first polarization state onto a third focal plane and a second state that focuses light of the second linear polarization state onto a fourth focal plane.

[0010] The liquid crystal wave plate and the first liquid crystal lens can share a first common substrate, and the first liquid crystal lens and the second liquid crystal lens can share a second common substrate. The first and second liquid crystal lenses can transmit light of the second and first linear polarization states, respectively. The first liquid crystal lens can take more than 35 milliseconds (e.g., 100 milliseconds or more) to switch between the first and second states.

[0011] The electro-active lens system may also include a display in optical communication with the liquid crystal waveplate and configured to emit light in a first linear polarization state, and a processor operatively coupled to the liquid crystal waveplate, the first liquid crystal lens, the second liquid crystal lens, and the display and configured to control the retardation of the liquid crystal waveplate, the first liquid crystal lens, the second liquid crystal lens, and the display.

[0012] All combinations of the foregoing concepts, and additional concepts discussed in more detail below (provided such concepts are not mutually inconsistent), are considered to be part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are considered to be part of the inventive subject matter disclosed herein. The terms explicitly used in any disclosure incorporated by reference herein should be given the meaning most consistent with the specific concepts disclosed herein. [Brief explanation of the drawings]

[0013] Those skilled in the art will appreciate that the drawings are presented primarily for illustrative purposes and are not intended to limit the scope of the inventive subject matter described herein. The drawings are not necessarily to scale, and in some instances, various aspects of the inventive subject matter disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate an understanding of different features. In the drawings, like reference characters generally refer to like features (e.g., functionally similar and / or structurally similar elements).

[0014] [Figure 1] 1A-1C show notations for linearly polarized light. [Figure 2] 2A to 2C show notations for the liquid crystal alignment (rubbing) direction. [Figure 3A] FIG. 3A shows an exploded view of an exemplary fast switching electro-active lens system having a fast polarization modifier followed by a pair of slower electro-active lenses. [Figure 3B] FIG. 3B shows an integrated fast switching electro-active lens system. [Figure 4] Figure 4A shows a cross-sectional view of the high-speed polarization orientation adjuster (variable retarder) in the off state, and Figure 4B shows a cross-sectional view of the high-speed polarization orientation adjuster (variable retarder) of Figure 4 in the on state. [Figure 5] FIG. 5 shows a fast switching lens system having a fast polarization changer followed by a pair of slower electro-active lenses, both of which are off (not focusing light). [Figure 6] FIG. 6 shows the fast switching lens system of FIG. 5 with the fast polarization changer off (changing polarization states) and the first electro-active lens on (focusing light). [Figure 7] FIG. 7 shows the fast switching lens system of FIG. 5 with the fast polarization changer on (not changing the polarization state) and the second electro-active lens on (focusing the light). [Figure 8]FIG. 8 shows a process for operating a fast-switching lens system in an augmented or virtual reality system, having a fast polarization changer followed by a pair of slower electro-active lenses. DETAILED DESCRIPTION OF THE INVENTION

[0015] A fast-switching electro-active lens system can change the focus of linearly polarized light from an object, such as a display in an augmented reality headset, in a period of less than 35 milliseconds (e.g., 30, 25, 20, 15, 10, 5, or fewer milliseconds). It does this with a combination of fast-switching waveplates and slow-switching liquid crystal lenses. Each lens has two eigenaxes that are orthogonal to each other and to the optical axis of the lens. Each lens focuses light polarized along one eigenaxes (the focusing eigenaxes) and transmits light polarized along the other eigenaxes (the transmission eigenaxes). The amount of focus along the focusing eigenaxes of the lens, i.e., its optical power, depends, among other things, on the thickness of the liquid crystal and the applied voltage, and may be adjusted continuously (e.g., from -5 to +5 diopters) or may be switched between two or more discrete states (e.g., between 0 and 5 diopters in 0.5 or 1.0 diopter increments). Each lens can provide no optical power (zero) when off (no voltage applied), or can provide a non-zero optical power when off. Other ranges and values ​​of optical power are possible.

[0016] The lenses are aligned such that their optical axes coincide but their eigenaxes are rotated 90° relative to one another. The focusing eigenaxes of the first lens are parallel to the transmitting eigenaxes of the second lens, and the transmitting eigenaxes of the first lens are parallel to the focusing eigenaxes of the second lens. The optical axes of the lenses coincide with the optical axes of the waveplates, and the eigenaxes of the waveplates are aligned with the eigenaxes of the lenses. In other words, when viewed along the surface normal (the optical axis of the fast switching electro-active lens system), the waveplates and lenses have coincident surface normals and aligned eigenaxes.

[0017] The lenses are aligned with their focusing and transmitting eigenaxes rotated by 90°, so that when the system is illuminated by light linearly polarized along one of the system's eigenaxes, one lens focuses the light and the other lens transmits it. Converting the polarization state of the incident light to an orthogonal linear polarization state (e.g., from horizontal to vertical, or +45° to -45°) changes the behavior of the lenses. Waveplates change state much faster than lenses, allowing for a much faster, user-observable transition from one power to another than would be possible if a single lens provided all of the optical adjustment. Also, if the transitions do not occur frequently (e.g., at intervals longer than the lens switching time), one lens can be switched between power levels while the other lens focuses the light, ready for the next transition.

[0018] Polarization state and liquid crystal alignment direction 1A, 1B, and 1C illustrate symbols used in this disclosure to describe different linear polarization orientations or states. Symbol 5 in FIG. 1A indicates that the direction of linear polarization is as if "into and out of the plane of the figure." Symbol 10 in FIG. 1B indicates that the direction of linear polarization is orthogonal to the direction indicated by symbol 5. In this case, the direction of linear polarization is "left and right across the plane of the figure." Symbol 15 in FIG. 1C indicates that the direction of linear polarization is also orthogonal to the direction indicated by symbol 5. The direction of linear polarization indicated by symbol 15 is "up and down across the plane of the figure."

[0019] 2A, 2B, and 2C illustrate symbols used in this disclosure to describe the rubbing or alignment directions of alignment layers used in liquid crystal focus changers (electro-active lenses). Symbol 20 in FIG. 2A indicates that the rubbing direction is as if "into or out of the plane of the figure." Symbol 25 in FIG. 2B indicates that the rubbing direction is perpendicular to the direction indicated by symbol 20; in this case, the rubbing direction is "left and right across the plane of the figure." Symbol 30 in FIG. 2C indicates that the rubbing direction is perpendicular to the direction indicated by symbols 20 and 25; the rubbing direction is "up and down across the plane of the figure." Each liquid crystal lens typically has two alignment layers, one on each side of the liquid crystal material, whose rubbing directions may be parallel, antiparallel, or perpendicular to each other. In some cases, only one alignment layer may be used to reduce cost. Using two alignment layers increases both switching speed and field of view.

[0020] The symbols shown in Figures 1A-1C and 2A-2C indicate relative directions. If different views are from different perspectives, different symbols may be used to indicate the same polarization state in the different views. Similarly, if different views are from different perspectives, the same symbols may be used to indicate different polarization states in the different views. For example, in a side or projection view of an optical component, symbol 5 may indicate a horizontal polarization state, and symbol 10 may indicate a vertical polarization state. In an end-on view (i.e., a view along the optical axis) of the same optical component, symbol 10 may indicate a horizontal polarization state, and symbol 15 may indicate a vertical polarization state.

[0021] High-speed electro-active lens switching system FIG. 3A shows an exploded view of a fast-switching lens system 300 including a polarization orientation changer (also called a polarization rotator, polarization adjuster, or variable retarder) 40 in optical communication with a first electro-active lens 50 and a second electro-active lens 60. The polarization orientation changer 40, the first electro-active lens 50, and the second electro-active lens 60 are optically in series with one another or stacked on top of one another. The lens system 300 may utilize planar liquid crystals, such as Merck MLC-2140, in all three components 40, 50, and 60. The first electro-active lens 50 has its alignment layer aligned orthogonally to the alignment layer of the second electro-active lens 60. In this case, the first electro-active lens 50 has a horizontally aligned liquid crystal rubbing direction 25, and the second electro-active lens 60 has a vertically aligned liquid crystal rubbing direction 30. Other rubbing directions (e.g., ±45° rubbing directions) are possible and are typically used when less than 100% focusing is required (in other words, only a portion of the light is focused while other portions pass through unfocused).

[0022] While the device 300 shown in FIG. 3A is a preferred embodiment, additional polarization switches may be added to provide additional functional control options. For example, the device 300 of FIG. 3A can quickly switch the optical power of lenses 50 and 60. If an additional polarization switch is positioned between lenses 50 and 60, activating both polarization switches can change the polarization state of light propagating through the system such that both lenses 50, 60 focus the light. More specifically, the first polarization switch 40 can switch light from the second polarization state 10 to the first polarization state 15, and the second polarization switch (not shown) can switch light from the first polarization state 15 to the second polarization state 10. Alternatively, both polarization switches can be activated such that neither lens 50, 60 focuses the light, even though one or both lenses are activated to provide optical power or are switched between states. This can be useful for providing greater optical power than provided by a single lens.

[0023] In operation, linearly polarized light 35 from an object (e.g., a display or spatial light modulator in an augmented or virtual reality system) enters the polarization rotator 40 in a second polarization state (e.g., vertically polarized as indicated by symbol 10). When the polarization rotator 40 is in a first state (e.g., off), as shown in FIG. 3A, it emits light 45 in a first polarization state, which may be rotated 90° relative to a second polarization state (e.g., horizontally polarized as indicated by symbol 15). When the polarization rotator 40 is in a second state (e.g., on), it emits light 45 whose polarization state is the same as the input light 35 (horizontally polarized in this example).

[0024] Light 45 exiting polarization adjuster 40 enters first electro-active lens 50, which reflects light 45 in a first polarization state (e.g., vertical polarization) and first electro-active lens 50 reflects light in a first state. When light 45 is in a first polarization state and first electro-active lens 50 is in a second state (e.g., off), first electro-active lens 50 focuses light 45 to a first focal plane. When light 45 is in a first polarization state and first electro-active lens 50 is in a second state (e.g., off), first electro-active lens 50 focuses light to a second focal plane. When light 45 is in a second polarization state (e.g., horizontally polarized), it passes through first electro-active lens 50 without being focused by first electro-active lens 50.

[0025] Light 55 exiting the first electro-active lens 50 enters a second electro-active lens 60, which, like the first electro-active lens 50, is switchable between two states (e.g., an on state and an off state). However, unlike the first electro-active lens 50, the second electro-active lens 60 only operates on light in a second polarization state (e.g., horizontally polarized). When the second electro-active lens 60 is in the first state, it focuses light in the second polarization state onto a third focal plane. Also, when the second electro-active lens 60 is in the second polarization state, it focuses light in the second polarization state onto a fourth focal plane. Light 55 in the first polarization state (e.g., vertically polarized) passes through the second electro-active lens 60 without being focused by the second electro-active lens 60. Light 65 exits the second electro-active lens 60 and system 300.

[0026] If the first electro-active lens 50 and the second electro-active lens 60 provide different power levels, the lens system 300 can switch between focal lengths of a range of different power levels by activating the polarization switcher 40, the first electro-active lens 50, and the second electro-active lens 60. For example, if the first electro-active lens 50 can be switched between power levels of 0.0 and 1.0 diopters (first / on and second / off states, respectively) and the second electro-active lens 50 can be switched between power levels of 0.5 and 1.5 diopters (first / on and second / off states, respectively), the lens system 300 can be switched between power levels of 0.0, 0.5, 1.0, and 1.5 diopters by activating the polarization switcher 40, the first electro-active lens 50, and the second electro-active lens 60. These power levels are merely examples, and other optical power levels are possible, including non-equally spaced power levels, such as powers selected to focus objects at near, near-midrange, midrange, far-midrange, and / or far planes.

[0027] The fast switching speed of polarization adjuster 40 allows lens system 300 to switch between these optical power levels quickly (e.g., within 30 milliseconds), even though first and second electro-active lenses 50 and 60 may switch slowly (e.g., over 100 milliseconds). For example, while first electro-active lens 50 is on and polarization adjuster 40 is off, second electro-active lens 60 can transition from one optical power to another without affecting light propagating through lens system 300. Once second lens 60 has completed its transition and is ready and at the desired optical power, polarization adjuster 40 switches states to focus light onto second electro-active lens 60, while first electro-active lens 50 no longer focuses light, even though it is still on.

[0028] 3A shows the components in an exploded perspective view with gaps between them. While the lens system works with gaps as shown in FIG. 3A, lens systems can also be fabricated with components bonded or integrated next to each other to eliminate reflections at the interfaces. For example, first electro-active lens 50 can share a first substrate with polarization orientation changer 40 and a second substrate with second electro-active lens 60.

[0029] 3B shows an integrated fast-switching electro-active lens system 350. In this system 350, substrates 41 and 43, together with liquid crystal layer 42, form polarization adjuster 40. Substrates 43 and 46, together with liquid crystal layer 44, form first lens 50. Substrates 46 and and 48 together with liquid crystal layer 47 form second lens 60. Substrates 43 and 46 are shared by multiple components and are therefore coated on each side with separate alignment layers and independently actuated electrodes (not shown).

[0030] High-speed polarization adjuster (variable retarder) 4A and 4B show cross-sectional side views of polarization adjuster 40. Fig. 4A shows adjuster 40 in an unpowered or off (first) state, while Fig. 4B shows adjuster 40 in a powered or on (second) state.

[0031] The polarization adjuster 40 is comprised of a first substrate 72 and a second substrate 80. A planar liquid crystal (e.g., Merck MLC-2140 nematic liquid crystal) is sandwiched and sealed between the two substrates 72 and 80. On the surface of the lower substrate 72 is a transparent conductive coating 75, also called an electrode (e.g., indium tin oxide (ITO)). On top of this electrode 75 is a transparent alignment layer (e.g., a polyimide made from Nissan Sunever 410 polyimide varnish). Typically, the alignment layer is applied, cured, and then rubbed with a felt cloth along the desired alignment direction. (Figures 2A-2C show possible rubbing directions for the alignment layer.) Adjacent to the electrode 75 is the liquid crystal. On the surface of the upper substrate 80 is another conductive coating (electrode) 85, which can be made of the same material as the first electrode 75.

[0032] FIG. 4A illustrates the difference between electrodes 75 and 85. When polarization modulator 40 is off, the alignment layer on first electrode 75 is configured to orient adjacent liquid crystal molecules in the direction indicated by symbol 25, while the alignment layer on second electrode 85 is configured to orient adjacent liquid crystal molecules in the direction indicated by symbol 20. As a result of this configuration, the liquid crystal molecules align in orientation / direction 25 at first electrode 75, in orientation / direction 20 at second electrode 85, and somewhere between orientations 25 and 20 in the middle of the liquid crystal layer, gradually twisting as the liquid crystal approaches orientations 25 and 20 as it approaches first electrode 75 and second electrode 85, respectively. This twisted configuration is illustrated by three symbols 100 in FIG. 4A. This twist of the liquid crystal molecules adjusts or changes the polarization direction of light 105 from polarization orientation 10 when entering polarization modulator 40 to polarization orientation 5 when exiting polarization modulator 40.

[0033] FIG. 4B shows polarization modulator 40 with voltage supply 110 applying a field potential to first electrode 75 while applying an opposite field potential to second electrode 85. The applied voltage may be an alternating current (AC) signal, such as a sine wave or square wave. When power is applied, the liquid crystal molecules reorient from direction 100 to direction 115, as shown in FIG. 4B. In this state, the polarization orientation 10 of light 105 entering the polarization modulator is identical to the polarization orientation 10 of light 105 upon exiting the polarization modulator. In other words, applying a voltage to electrodes 75 and 85 changes the phase difference of the polarization modulator from π / 2 to 0. Polarization modulator 40 does not change the direction of light propagation.

[0034] Other configurations of polarization modulators are possible. For example, the alignment layers can have parallel or antiparallel rub directions instead of the crossed or orthogonal rub directions of Figures 4A and 4B. With parallel or antiparallel rub directions, the polarization modulator does not change the polarization state of the incident light when the incident light is off (i.e., when no voltage is applied across the liquid crystal by the electrodes), and its nominal phase difference is zero. Instead, when the polarization modulator is on (i.e., when a voltage is applied across the liquid crystal by the electrodes), it changes the polarization state of the incident light, for example, by changing the horizontal or vertical polarization for a phase difference change of π / 2.

[0035] The design parameters of the polarization adjuster, including the liquid crystal material and liquid crystal thickness, can be selected to increase the switching speed. The following equations are the design parameters for achieving fast switching speed and high optical efficiency: An example set is shown. Some exemplary turn-off times (showing preferred liquid crystal thicknesses of either 2.4 micrometers or 5.3 micrometers) are shown, but turn-on times can be reduced by using higher switching voltages than necessary. The liquid crystal used in the preferred embodiment is HAE614752 manufactured by Jiangsu Hecheng Display Technology Co., China. Other liquid crystals, such as MLC2136 manufactured by Merck Chemicals, Germany, can also be used.

[0036] For a twisted nematic liquid crystal cell placed between two polarizers aligned parallel and perpendicular to their respective surface molecular directors, the transmission is:

number

number

[0037] A half-wave retardation (i.e., JPEG2025128290000018.jpg927 A polarization switcher providing this should have a liquid crystal layer whose thickness meets the minimum transmission criteria using the equation above. JPEG2025128290000019.jpg1036 JPEG2025128290000020.jpg944 For a liquid crystal layer with a viscosity of 100 mPa and K=10 pN, the thickness of the liquid crystal layer should be 2.4 μm or 5.3 μm for a switching time of 6 ms or 29 ms, respectively. These switching times are short enough for the polarization switch to change state (e.g., turn on or off) without a delay noticeable to the human eye.

[0038] Operation of a fast-switching electro-active lens system 5-7 illustrate the operation of a fast-switching electro-active lens system 500 having a polarization adjuster 120, a first electro-active (liquid crystal) lens 125, and a second electro-active (liquid crystal) lens 130, all of which are optically in series with one another. The first electro-active lens 125 has an alignment layer rubbed with orientation 30, and the second electro-active lens 130 has an alignment layer rubbed with an orthogonal orientation 20. While FIGS. 5-7 show gaps between the components, the components may contact one another, be bonded together, or otherwise integrated to form a single unit, such as system 350 in FIG. 3B. The fast-switching electro-active lens system 500 focuses and / or transmits polarized light emitting onto a display 520, such as a transparent organic light-emitting diode (OLED) display in an augmented reality system. The fast switching electro-active lens system 500 and the display 520 are operably coupled to a processor 510, which can control the polarization adjuster 120, the first electro-active lens 125, and the second electro-active lens 130 in response to content (video images) displayed on the display 520.

[0039] In Figure 5, polarization modulator 120 is in the off state, as are electro-active lenses 125 and 130. Light enters polarization modulator 120 with polarization orientation 5 and exits with orientation 15 (i.e., changes from one linear polarization state to the orthogonal linear polarization state). In this example, when polarization modulator 120 and lens 125 are in the electrically off state and lens 130 is switched to the electrically on state, no optical focusing occurs because the rub orientation of lens 130 is orthogonal to the polarization state of the light entering lens 130. In other words, when first electro-active lens 125 has no optical power in the off state and second electro-active lens 130 does not act on light with polarization orientation 15, system 500 does not focus incident light.

[0040] 6 shows polarization adjuster 120 still in its electrically-off state and first and second electro-active lenses 125 and 130 in their electrically-on states. In this configuration, first electro-active lens 125 has optical power due to the voltage actuating its liquid crystal material, changing its refractive index profile. Because the polarization of light entering first electro-active lens 125 matches the orientation of the rubbing direction 30 of the first electro-active lens, first electro-active lens 125 focuses the incident light. However, second electro-active lens 130 does not focus light, regardless of its setting, because its rubbing direction 20 is orthogonal to the light's polarization orientation 15.

[0041] 7 shows polarization modulator 120, first electro-active lens 125, and second electro-active lens 130 in an electrically on state (i.e., a voltage is applied across its liquid crystal layer). In this state, polarization modulator 120 does not convert the polarization state of the incident light; instead, polarization modulator 120 transmits the incident light in polarization orientation 5. This means that the light emerging from polarization modulator 120 is no longer polarized in the same orientation as rub direction 30 of first electro-active lens 125, but is now polarized in the same orientation as rub direction 20 of second electro-active lens 130. As a result, second electro-active lens 130 focuses the incident light, but first electro-active lens 125 does not. If the second electro-active lens 130 has a higher refractive power (shorter focal length) than the first electro-active lens 125, as shown in FIG. 7, this change in polarization state will change the refractive power (focal length) of the lens system 500 even though the states of the first and second electro-active lenses 125 and 130 have not changed.

[0042] Displaying video with a fast-switching electroactive lens system. Figure 8 illustrates a process by which a fast-switching electro-active lens system, such as the systems of Figures 3 and 5-7, can be used to adjust the focus of a virtual image appearing in a video or other dynamic environment presented via an augmented, mixed, or virtual reality system. In the following example, the electro-active lens system includes a polarization-changing component (or polarization changer) that can switch between state A (e.g., π / 2 phase difference) and state B (e.g., 0 phase difference) in 35 milliseconds, and two focus-changing components (electro-active lenses or focus changers, Lenses A and B), each of which can switch states in approximately 350 milliseconds. The electro-active lens system is used in an augmented / virtual reality system that displays a video clip that is 8 seconds in duration. The display of the video clip involves changing the focus every 2 seconds, with the focus change occurring in 35 milliseconds so that it is apparent to the viewer.

[0043] This example video clip begins with a digital image at a long distance. At the 2-second mark, the simulated distance of the digital image changes from long to long-middle distance, as shown by the bottom line in Figure 8. At the 4-second mark, the simulated distance changes from long-middle distance to close. At the 6-second mark, the simulated distance changes from close to close. And at the 8-second mark, the simulated distance changes from close to close.

[0044] For the purposes of this example, the simulated distances for far, far-middle, medium, and near are 6 meters, 2 meters, 1 meter, and 0.5 meters, respectively. To view images at these distances, the electro-active lens system rotates in the same order, 0.5 meters, 1 meter, and 0.5 meters, respectively. The lenses provide net perceptible powers of 0, 1 / 2, 1, and 2 diopters. In this example, Lens A and Lens B are each switchable between at least a subset of these powers, with Lens A being switchable between a 0 diopter state and a 2 diopter state, and Lens B being switchable between a 0 diopter state, a 1 / 2 diopter state, and a 1 diopter state.

[0045] In this example, when the polarization modifier is in state A, Lens A is optically present and Lens B is not present. When the polarization modifier is in state B, Lens A is optically absent and Lens B is present. That is, Lens A focuses light transmitted by the polarization modifier in state A but not when the polarization modifier is in state B, and Lens B focuses light transmitted by the polarization modifier in state B but not when the polarization modifier is in state A. A lens that is not focusing light, either because the lens is not activated or because the incident light is in a polarization state that is not focused by the lens, provides an optical power of 0 diopters.

[0046] At the start of the video, the polarization changer is in state A, lens A is off and therefore has 0 diopters, and lens B is also off and has 0 diopters because the polarization changer is in state A. The net perceptible optical power of the electro-active lens system is 0 diopters.

[0047] Shortly after the video clip begins, for example, at the 1-second mark, a processor coupled to or integrated with the electro-active lens instructs Lens B to switch its optical power from 0 diopters to 1 / 2 diopters. While Lens B changes focus, the polarization changer makes Lens B optically absent (the polarization changer is still in State A), so the observer cannot see the optical effect occurring in Lens B. Lens B takes a full 1 second to complete the change to its new optical power, which is much longer than necessary. At the 2-second mark in the video clip, the polarization changer switches state from State A to State B, making Lens B optically present and changing the net perceptible optical power of the system from 0 diopters to 1 / 2 diopters in 35 milliseconds.

[0048] Shortly after the 2-second mark, for example, at the 3-second mark, the processor instructs Lens A to switch its optical power from 0 to 2 diopters. While Lens A changes focus, the polarization changer makes Lens A optically absent (because the polarization changer is still in state B, the net perceptible optical power of the electro-active lens system remains 1 / 2 diopter), so the observer cannot see the optical effect occurring in Lens A. Lens A takes a full second to complete the change to its new optical power, which is much longer than necessary. At the 4-second mark in the video clip, the polarization changer again switches state, making Lens A optically present and Lens B optically absent, resulting in the net perceptible optical power of the system changing from 1 / 2 diopter to 2 diopters in 35 milliseconds.

[0049] Shortly after the 4-second mark, say at the 5-second mark, the processor instructs Lens B to switch power from 1 / 2 diopter to 1 diopter. Because the polarization changer renders Lens B optically absent during the transitional state of the change, the user cannot see any optical effects. Lens B takes a full second to complete the change to its new power, which is much longer than necessary. At the 6-second mark in the video clip, the polarization changer switches states, resulting in a change in the system's net perceptible power from 2 diopters to 1 diopter in 35 milliseconds.

[0050] Shortly after the 6 second mark, say at 7 seconds, Lens A is instructed to switch power from 1 diopter to 0 diopters. The polarization changer places Lens A in an optically inactive state (it is still in state B) while Lens A changes focus again. Therefore, the observer cannot see the optical effect occurring in Lens A. Lens A takes a full second to complete the change to its new power, which is much longer than is necessary. At the 8-second mark in the video clip, the polarization changer again switches states, making Lens A optically present and Lens B optically absent, resulting in the net perceptible power of the system changing from 2 diopters to 0 diopters in 35 milliseconds.

[0051] This arrangement may be varied and repeated as desired and may be correlated to and coordinated by signals from a controller or processor that presents the digital image.

[0052] Although the lens may take hundreds of milliseconds to change focus, the observer sees each focus change occur within 35 milliseconds.

[0053] The video output can be prepared in advance and programmed / controlled to coordinate with the electro-active lens components to reduce the observer's perception of focus switching times. However, in some cases, the video image may not be prepared in advance and cannot be used to control switching in this pre-programmed manner. Instead, the electro-active lens operates in an on-demand switching mode controlled by the observer using a switch or other command device. In these cases, a similar strategy may be employed in which the polarization changer can be delayed from changing state from one state to another until the focus change period is complete, resulting in the user seeing a 35 millisecond optical switching period and a 350 millisecond delay between the switch command and execution, which may be preferable to having the user experience a 350 millisecond focus change duration.

[0054] In another embodiment, a single electro-active lens may be used with a polarization rotator. The use of two adjustable lenses allows for an almost infinite combination of fast-switching configurations from one power to another, e.g., from 1 diopter to 2 diopters to ½ diopter to 1 diopter to ½ diopter, while the use of a single lens allows for fast switching between zero and another power, e.g., 0 diopter, then another power, then 0 diopter, etc.

[0055] The system works with randomly polarized light entering the system (e.g., unpolarized emission from an unpolarized OLED display), but works best with polarized light. Unpolarized or randomly polarized light can be polarized with a polarizing filter located at the light entry point of the system, or by using display technologies that emit polarized light, such as LED displays or polarized OLED displays.

[0056] conclusion While various inventive embodiments have been described and illustrated herein, those skilled in the art will readily envision a variety of other means and / or structures for performing the functions and / or obtaining the results and / or one or more advantages described herein, and each of such variations and / or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on the specific application(s) for which the teachings of the present invention are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. Accordingly, the foregoing embodiments are presented by way of example only, and it will be understood that, within the scope of the appended claims and their equivalents, inventive embodiments may be practiced otherwise than as specifically described and claimed. Embodiments are directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods is within the inventive scope of the present disclosure, provided that such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

[0057] The above embodiments can be implemented in any of numerous ways. For example, the design and construction of embodiments of the techniques disclosed herein may be implemented using hardware, software, or a combination thereof. If implemented in software, the software code may be executed on any suitable processor or collection of processors, whether provided on a single computer or distributed among multiple computers.

[0058] Also, various inventive concepts may be embodied as one or more methods, examples of which have been provided. Acts performed as part of a method may be ordered in any suitable manner. As a result, embodiments may be constructed in which acts are performed in a different order than illustrated, which may include performing some acts simultaneously, even though the exemplary embodiments show acts as sequential.

[0059] All definitions defined and used herein should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0060] The indefinite articles "a" and "an," as used in the specification and claims, unless expressly indicated otherwise, should be understood to mean "at least one."

[0061] The term "and / or," as used in the specification and claims, should be understood to mean "either or both" of the associated elements, i.e., elements that are conjunctive in some cases and disjunctive in other cases. Multiple elements listed with "and / or" should be construed in the same manner, i.e., "one or more" of the conjunctive elements. Other elements, whether related or unrelated to the elements specifically identified, may optionally be present other than the elements specifically identified by the "and / or" clause. Thus, as a non-limiting example, a reference to "A and / or B," when used in conjunction with open-ended language such as "comprising," can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements), etc.

[0062] As used herein and in the claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be construed as inclusive, i.e., the inclusion of at least one, but also two or more, of the number or list of elements, and optionally additional items not listed. Terms clearly indicated to the contrary, such as "only one of" or "exactly one of," or, when used in the claims, "consisting of," only refer to the inclusion of exactly one element of the number or list of elements. Generally, as used herein, the term "or" shall only be construed to indicate exclusive alternatives (i.e., "one or the other, but not both") when preceded by exclusive terms, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0063] As used in this specification and claims, the phrase "at least one" in connection with a list of one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed in the list of elements, and not excluding any combination of elements in the list of elements. This definition also allows for the optional presence of elements other than those specifically identified in the list of elements referred to by the phrase "at least one," whether related or unrelated to the specifically identified elements. Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B," or equivalently, "at least one of A and / or B") can refer to at least one A (optionally including elements other than B), in one embodiment, where B is absent, and optionally including two or more As; at least one B (optionally including elements other than A), in another embodiment, where A is absent, and optionally including two or more Bs; at least one A, optionally including two or more As, and at least one B (optionally including other elements), in yet another embodiment, where two or more As are present, and optionally two or more Bs; and so forth.

[0064] In the claims, as well as in the above specification, all transitional phrases, such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," "composed of," and the like, are to be understood as open-ended, i.e., meaning including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as defined in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

Claims

[Claim 1] 1. An electro-active lens system comprising: a polarization changer switchable between a first state in which the polarization changer switches the polarization of light between a first polarization state and a second polarization state, and a second state in which the polarization changer transmits light in the first polarization state; a first electro-active lens in optical communication with the polarization switcher, the first electro-active lens switchable between a first focusing state, in which the first electro-active lens focuses light in the first polarization state and transmits light in the second polarization state, and a first transmitting state, in which the first electro-active lens transmits light in the first polarization state and the second polarization state; an electro-active lens system comprising: a second electro-active lens in optical communication with the polarization switcher and the first electro-active lens, the second electro-active lens switchable between a second focusing state, in which the second electro-active lens transmits light in the first polarization state and focuses light in the second polarization state, and a second transmitting state, in which the second electro-active lens transmits light in the first polarization state and the second polarization state.

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