Spectacles with electrically-tunable lenses controllable by an external system

A system for controlling at least one focus aspect of adaptive spectacles (10) having at least one electrically-tunable lens (22), the system including a housing (14), which is physically separate from adaptive spectacles (10), a display screen (16) mounted in housing (14), a sensor (19) mounted in housing (14) and configured to detect a relative position of adaptive spectacles (10) with respect to display screen (16), an interface (17) configured to communicate with adaptive spectacles (10), and a controller (15) configured to receive an input signal from sensor (19), the input signal being indicative of the relative position of adaptive spectacles (10) with respect to display screen (16) and output, in response to the input signal, a command signal for sending to adaptive spectacles (10) via interface (17) to adjust the at least one focus aspect of the at least one electrically-tunable lens (22).

FIELD OF THE INVENTION

The present invention relates generally to optical devices, and particularly to electrically-tunable lenses.

BACKGROUND OF THE INVENTION

Tunable lenses are optical elements whose optical characteristics, such as the focal length and/or the location of the optical center, can be adjusted during use, typically under electronic control. Such lenses may be used in a wide variety of applications. For example, U.S. Pat. No. 7,475,985 describes the use of an electro-active lens for the purpose of vision correction.

Electrically-tunable lenses typically contain a thin layer of a suitable electro-optical material, i.e., a material whose local effective index of refraction changes as a function of the voltage applied across the material. An electrode or array of electrodes is used to apply the desired voltages in order to locally adjust the refractive index to the desired value. Liquid crystals are the electro-optical material that is most commonly used for this purpose (wherein the applied voltage rotates the molecules, which changes the axis of birefringence and thus changes the effective refractive index), but other materials, such as polymer gels, with similar electro-optical properties can alternatively be used for this purpose.

Some tunable lens designs use an electrode array to define a grid of pixels in the liquid crystal, similar to the sort of pixel grid used in liquid-crystal displays. The refractive indices of the individual pixels may be electrically controlled to give a desired phase modulation profile. (The term “phase modulation profile” is used in the present description and in the claims to mean the distribution of the local phase shifts that are applied to light passing through the layer as the result of the locally-variable effective refractive index over the area of the electro-optical layer of the tunable lens.) Lenses using grid arrays of this sort are described, for example, in the above-mentioned U.S. Pat. No. 7,475,985.

PCT International Publication WO 2014/049577, whose disclosure is incorporated herein by reference, describes an optical device comprising an electro-optical layer, having an effective local index of refraction at any given location within an active area of the electro-optical layer that is determined by a voltage waveform applied across the electro-optical layer at the location. An array of excitation electrodes, including parallel conductive stripes extending over the active area, is disposed over one or both sides of the electro-optical layer. Control circuitry applies respective control voltage waveforms to the excitation electrodes and is configured to concurrently modify the respective control voltage waveforms applied to excitation electrodes so as to generate a specified phase modulation profile in the electro-optical layer.

U.S. Patent Application Publication 2012/0133891 describes an electro-optical apparatus and method for correcting myopia that includes at least one adaptive lens, a power source, and an eye tracker. The eye tracker includes an image sensor and a processor operatively connected to the adaptive lens and the image sensor. The processor is configured to receive electrical signals from the image sensor and to control the correction power of the adaptive lens to correct myopia, with the correction power dependent on a user's gaze distance and myopia prescription strength.

SUMMARY

There is provided in accordance with an embodiment of the present disclosure, a system for controlling at least one focus aspect of adaptive spectacles having at least one electrically-tunable lens, the system including a housing, which is physically separate from the adaptive spectacles, a display screen mounted in the housing and configured to be viewed through the adaptive spectacles by a person, a sensor mounted in the housing and configured to detect a relative position of the adaptive spectacles with respect to the display screen, an interface configured to communicate with the adaptive spectacles, and a controller configured to receive an input signal from the sensor, the input signal being indicative of the relative position of the adaptive spectacles with respect to the display screen, and output, in response to the input signal, a command signal for sending to the adaptive spectacles via the interface to adjust the at least one focus aspect of the at least one electrically-tunable lens.

Further in accordance with an embodiment of the present disclosure, the command signal is indicative of at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

Still further in accordance with an embodiment of the present disclosure, the controller is configured to calculate, based on the relative position, the at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

Additionally, in accordance with an embodiment of the present disclosure, the controller is configured to calculate the at least one refractive power, based on the relative position and a given visual accommodation capability of the person wearing the adaptive spectacles.

Moreover, in accordance with an embodiment of the present disclosure, the system includes the adaptive spectacles, the adaptive spectacles being configured to receive the command signal and adjust the at least one electrically-tunable lens to provide the at least one refractive power.

Further in accordance with an embodiment of the present disclosure, the command signal is indicative of an optical center of the at least one electrically-tunable lens to which the at least one electrically-tunable lens is to be adjusted in order to align a line-of-sight of the person wearing the adaptive spectacles and viewing the display screen with the optical center of the at least one electrically-tunable lens.

Still further in accordance with an embodiment of the present disclosure, the controller is configured to calculate the optical center of the at least one electrically-tunable lens based on the relative position so that the line-of-sight of the person wearing the adaptive spectacles and viewing the display screen is aligned with the optical center of the at least one electrically-tunable lens when the at least one electrically-tunable lens will be adjusted.

Additionally, in accordance with an embodiment of the present disclosure, the system includes the adaptive spectacles, the adaptive spectacles being configured to receive the command signal and adjust the optical center of the at least one electrically-tunable lens to align the line-of-sight of the person wearing the adaptive spectacles and viewing the display screen with the optical center of the at least one electrically-tunable lens.

Moreover, in accordance with an embodiment of the present disclosure, the interface, the controller, the sensor, and the display screen are implemented in a mobile device.

Further in accordance with an embodiment of the present disclosure, the sensor includes a front-facing camera disposed adjacent to the display screen, and the controller is configured to determine the relative position of the adaptive spectacles with respect to the display screen based on image analysis of images captured by the front-facing camera of the mobile device.

Still further in accordance with an embodiment of the present disclosure, the sensor includes a depth-sensor.

Additionally in accordance with an embodiment of the present disclosure, the controller is configured to determine when the person wearing the adaptive spectacles is viewing or using the display screen, and in response to determining that the person wearing the adaptive spectacles is viewing or using the display screen determine the relative position, and prepare the command signal, based on the relative position, for sending to the adaptive spectacles to adjust the at least one focus aspect of the at least one electrically-tunable lens.

Moreover, in accordance with an embodiment of the present disclosure, the controller is configured to determine when the person wearing the adaptive spectacles is viewing the display screen based on analyzing an eye gaze direction of the person captured by the sensor.

Further in accordance with an embodiment of the present disclosure, the sensor is implemented as part of a vehicle gaze detection system and the display screen is implemented as part of a vehicle instrument panel.

Still further in accordance with an embodiment of the present disclosure, the controller is configured to determine when the person wearing the adaptive spectacles is using the display screen based on user interaction with a touch sensitive portion of the display screen.

Additionally, in accordance with an embodiment of the present disclosure, the interface is configured to receive an orientation reading from the adaptive spectacles, and the controller is configured to correct the relative position based on the orientation reading.

Moreover in accordance with an embodiment of the present disclosure, the system includes a processor configured to execute an eye therapy software application to display a plurality of images on the display screen, the plurality of images being generated to challenge a visual accommodation capability of the person, wherein the controller is configured to calculate at least one refractive power to which the at least one electrically-tunable lens will be adjusted based on the relative position and a given visual accommodation capability to which the person is to be challenged, and prepare the command signal to include the at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

There is also provided in accordance with still another embodiment of the present disclosure, a system for controlling adaptive spectacles, the system including a mobile device including a housing, which is physically separate from the adaptive spectacles, a display screen mounted in the housing and configured to be viewed through the adaptive spectacles by a person, a sensor mounted in the housing and configured to detect a relative position of the adaptive spectacles with respect to the display screen, a first interface configured to communicate with the adaptive spectacles, and a controller configured to receive an input signal from a sensor, the input signal being indicative of the relative position of the adaptive spectacles with respect to the display screen, and output in response to the input signal, a command signal for sending to the adaptive spectacles via the first interface, and the adaptive spectacles including a spectacle frame, at least one electrically-tunable lens mounted in the spectacle frame, a second interface configured to receive the command signal from the device, and control circuitry configured to adjust the at least one focus aspect of the at least one electrically-tunable lens based on the command signal.

Further in accordance with an embodiment of the present disclosure, the command signal includes at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

Still further in accordance with an embodiment of the present disclosure, the control circuitry is configured to calculate, based on the relative position, at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

Additionally, in accordance with an embodiment of the present disclosure, the control circuitry is configured to calculate the at least one refractive power, based on the relative position and a given visual accommodation capability of the person.

Moreover, in accordance with an embodiment of the present disclosure, the control circuitry is configured to adjust the at least one electrically-tunable lens to provide the at least one refractive power.

Further in accordance with an embodiment of the present disclosure, the command signal includes an indication of an optical center of the at least one electrically-tunable lens to which the at least one electrically-tunable lens is to be adjusted in order to align a line-of-sight of the person wearing the adaptive spectacles and viewing the display screen with the optical center of the at least one electrically-tunable lens.

Moreover, in accordance with an embodiment of the present disclosure, the control circuitry is configured to calculate an optical center of the at least one electrically-tunable lens based on the relative position so that a line-of-sight of the person wearing the adaptive spectacles and viewing the display screen is aligned with the optical center of the at least one electrically-tunable lens when the at least one electrically-tunable lens will be adjusted.

Still further in accordance with an embodiment of the present disclosure, the control circuitry is configured to adjust the optical center of the at least one electrically-tunable lens to align the line-of-sight of the person wearing the adaptive spectacles and viewing the display screen with the optical center of the at least one electrically-tunable lens.

Additionally, in accordance with an embodiment of the present disclosure, the first interface is configured to receive an orientation reading from the adaptive spectacles, and the controller is configured to correct the relative position based on the orientation reading.

There is also provided in accordance with still another embodiment of the present disclosure, a system for managing eye therapy via at least one focus aspect of adaptive spectacles having at least one electrically-tunable lens, the system including an interface configured to communicate with the adaptive spectacles, a processor configured to execute an eye therapy software application to display a plurality of images on a display screen, the plurality of images being generated to challenge a visual accommodation capability of the person, and a controller configured to calculate at least one refractive power to which the at least one electrically-tunable lens will be adjusted at least based on a given visual accommodation capability to which the person is to be challenged, and output, to the adaptive spectacles via the interface, a command signal including the at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

There is also provided in accordance with still another embodiment of the present disclosure, a method for controlling at least one focus aspect of adaptive spectacles having at least one electrically-tunable lens, the method including detecting, using a sensor, a relative position of the adaptive spectacles with respect to a display screen configured to be viewed through the adaptive spectacles by a person, the display screen being mounted in a housing with the sensor, the housing being physically separate from the adaptive spectacles, communicating with the adaptive spectacles, receiving an input signal from the sensor indicative of the relative position of the adaptive spectacles with respect to the display screen, and outputting, in response to the input signal, a command signal for sending to the adaptive spectacles to adjust the at least one focus aspect of the at least one electrically-tunable lens.

Moreover, in accordance with an embodiment of the present disclosure, the command signal is indicative of at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

Further in accordance with an embodiment of the present disclosure, the method includes calculating, based on the relative position, at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

Still further in accordance with an embodiment of the present disclosure, the method includes calculating at least one refractive power, based on the relative position and a given visual accommodation capability of the person wearing the adaptive spectacles.

Additionally, in accordance with an embodiment of the present disclosure, the command signal is indicative of an optical center of the at least one electrically-tunable lens to which the at least one electrically-tunable lens is to be adjusted in order to align a line-of-sight of the person wearing the adaptive spectacles and viewing the display screen with the optical center of the at least one electrically-tunable lens.

Moreover, in accordance with an embodiment of the present disclosure, the method includes calculating an optical center of the at least one electrically-tunable lens based on the relative position so that a line-of-sight of the person wearing the adaptive spectacles and viewing the display screen is aligned with the optical center of the at least one electrically-tunable lens when the at least one electrically-tunable lens will be adjusted.

Further in accordance with an embodiment of the present disclosure, the method includes determining the relative position of the adaptive spectacles with respect to the display screen based on image analysis of images captured.

Still further in accordance with an embodiment of the present disclosure, the method includes determining when the person wearing the adaptive spectacles is viewing or using the display screen, and in response to determining that the person wearing the adaptive spectacles is viewing or using the display screen determining the relative position, and preparing the command signal, based on the relative position, for sending to the adaptive spectacles to adjust the at least one focus aspect of the at least one electrically-tunable lens.

Additionally, in accordance with an embodiment of the present disclosure, the method includes determining when the person wearing the adaptive spectacles is viewing the display screen based on analyzing an eye gaze direction of the person captured by the sensor.

Moreover, in accordance with an embodiment of the present disclosure, the method includes determining when the person wearing the adaptive spectacles is using the display screen based on user interaction with a touch sensitive portion of the display screen.

Further in accordance with an embodiment of the present disclosure, the method includes executing an eye therapy software application to display a plurality of images on the display screen, the plurality of images being generated to challenge a visual accommodation capability of the person, calculating at least one refractive power to which the at least one electrically-tunable lens will be adjusted based on the relative position and a given visual accommodation capability to which the person is to be challenged, and preparing the command signal to include the at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

There is also provided in accordance with still another embodiment of the present disclosure, a method for controlling adaptive spectacles, the method including performing in a mobile device including a housing which houses a sensor and a display screen detecting, using the sensor, a relative position of the adaptive spectacles with respect to the display screen configured to be viewed through the adaptive spectacles by a person, the housing being physically separate from the adaptive spectacles, communicating with the adaptive spectacles, receiving an input signal indicative of the relative position of the adaptive spectacles with respect to the display screen, and outputting, in response to the input signal, a command signal for sending to the adaptive spectacles to adjust the at least one focus aspect of the at least one electrically-tunable lens, and the adaptive spectacles adjusting the at least one focus aspect of at least one electrically-tunable lens of the adaptive spectacles based on the command signal.

Still further in accordance with an embodiment of the present disclosure, the command signal includes at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

Additionally, in accordance with an embodiment of the present disclosure, the method includes calculating, based on the relative position, at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

Moreover, in accordance with an embodiment of the present disclosure, the method includes calculating at least one refractive power, based on the relative position and a given visual accommodation capability of the person.

Further in accordance with an embodiment of the present disclosure, the method includes adjusting the at least one electrically-tunable lens to provide the at least one refractive power.

Still further in accordance with an embodiment of the present disclosure, the command signal includes an indication of an optical center of the at least one electrically-tunable lens to which the at least one electrically-tunable lens is to be adjusted in order to align a line-of-sight of the person wearing the adaptive spectacles and viewing the display screen with the optical center of the at least one electrically-tunable lens.

Additionally, in accordance with an embodiment of the present disclosure, the method includes calculating an optical center of the at least one electrically-tunable lens based on the relative position so that a line-of-sight of the person wearing the adaptive spectacles and viewing the display screen is aligned with the optical center of the at least one electrically-tunable lens when the at least one electrically-tunable lens will be adjusted.

Moreover, in accordance with an embodiment of the present disclosure, the method includes adjusting the optical center of the at least one electrically-tunable lens to align the line-of-sight of the person wearing the adaptive spectacles and viewing the display screen with the optical center of the at least one electrically-tunable lens.

There is also provided in accordance with still another embodiment of the present disclosure, a method for managing eye therapy via at least one focus aspect of adaptive spectacles having at least one electrically-tunable lens, the method including communicating with the adaptive spectacles, executing an eye therapy software application to display a plurality of images on a display screen, the plurality of images being generated to challenge a visual accommodation capability of the person, calculating at least one refractive power to which the at least one electrically-tunable lens will be adjusted at least based on a given visual accommodation capability to which the person is to be challenged, and outputting, to the adaptive spectacles via the interface, a command signal including the at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

There is also provided in accordance with still another embodiment of the present disclosure, a software product, including a non-transient computer-readable medium in which program instructions are stored, which instructions, when read by a central processing unit (CPU), cause the CPU to receive an input signal from a sensor, the input signal being indicative of a relative position of adaptive spectacles with respect to a display screen, which is configured to be viewed through the adaptive spectacles by a person, the display screen being mounted in a housing with the sensor, the housing being physically separate from the adaptive spectacles, and output, in response to the input signal, a command signal for sending to the adaptive spectacles to adjust the at least one focus aspect of the at least one electrically-tunable lens.

There is also provided in accordance with still another embodiment of the present disclosure, a software product, including a non-transient computer-readable medium in which program instructions are stored, which instructions, when read by a central processing unit (CPU), cause the CPU to communicate with adaptive spectacles having at least one electrically-tunable lens, execute an eye therapy software application to display a plurality of images on a display screen, the plurality of images being generated to challenge a visual accommodation capability of the person, calculate at least one refractive power to which the at least one electrically-tunable lens will be adjusted at least based on a given visual accommodation capability to which the person is to be challenged, and output, to the adaptive spectacles via the interface, a command signal including the at least one refractive power to which the at least one electrically-tunable lens will be adjusted.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

Embodiments of the present invention provide an automatic vision correction system comprising two sub-systems. One sub-system includes adaptive spectacles with electrically-tunable lenses (such as the ones described in PCT International Publication WO 2015/186010, whose disclosure is incorporated herein by reference) with a capability to connect to an external sub-system, and receive commands from that external sub-system to change the focal distance and/or optical center (also known as optical axis) of its tunable lenses and/or receive information that can be used by the adaptive spectacles to determine the needed focus change and/or an adjustment to the optical center. It should be noted that the optical center of one or more of the electrically-tunable lenses may be adjusted to accommodate an angle of view determined by the external sub-system. For example, the optical quality of a liquid crystal (LC) tunable lenses is optimal at the center of the lens, and degrades with the distance from the center. Since the LC lens is positioned at a distance from a person's eye, when the person rotates his/her eye to view different directions, the line-of-sight crosses the LC lens at different locations. By shifting the optical center of the tunable lens in accordance with the angle of view, thereby centering the LC lens with the line-of-sight, the lens quality can be improved, particularly when the user is looking through an area near the edge of the lens and/or when a lens with a narrow field of view is being used to implement the electrically-tunable lenses. Shifting optical centers of adaptive spectacles in a different setting is described in PCT International Publication WO 2017/182906, whose disclosure is incorporated herein by reference.

The second, “external” sub-system can be one of many types of computing-capable systems with a capability to connect to the adaptive spectacles and submit commands and/or information as described above. The external sub-system may be capable of determining the context of the use of the adaptive spectacles (for example, assess the relative position of the adaptive spectacles with respect to a display screen being viewed by the person wearing the adaptive spectacles in order to calculate the focus change and/or the adjustment to the optical center) or it may apply any desired policy to control the glasses (for example, execute a pre-determined set of focus-change commands as part of an accommodation training eye-therapy session). The term “relative position”, as used in the claims and the specification, is defined to include an angular orientation of the adaptive spectacles with respect to the display screen and/or at least one distance between the adaptive spectacles and the display screen.

Communication between the two sub-systems may be established using existing variety of standard and proprietary protocols. These may be wireless protocols, such as Bluetooth® or WiFi®, or wired protocols such as Universal Serial Bus (USB), or low-level serial protocols like Inter-integrated Circuit (I2C) or SPA. A higher-level-protocol providing a predefined set of commands and messages may be used between the two sub-systems to perform the interaction. That protocol may vary depending on the application and the identity of the external sub-system. Examples of such systems follow.

People with presbyopia have difficulty focusing to close distances, and in particular hand-held device distance, such as a mobile phone, which can be in the range of 25 cm-50 cm (+2 diopters to +4 diopters). One embodiment of the present invention provides a system that comprises a hand-held mobile device such as a mobile phone, a tablet, a smart watch, or an e-reader with a capability to determine the relative position of the adaptive spectacles with respect to the display screen of the mobile device. Such capability may be realized in various ways such as a dedicated depth-sensor (such as the depth sensor of Apple's iPhone® X), a front facing camera (camera located on the display side—either using single or multiple aperture to determine depth) with accompanying image-processing running on the device, and possibly other depth sensing components and techniques. The hand-held mobile device can determine that the user is currently using it, continuously assess the relative position of the adaptive spectacles with respect to the display screen, and communicate this information to the adaptive spectacles, or even command the adaptive spectacles to change focus and/or optical center(s) as needed.

For example, a user may have a limited accommodation ability of 1 diopter. When the user holds the device at a distance of 33 cm (3 diopters), the device will identify this distance, conclude that the user requires +2 diopter vision correction to that distance, and command the lenses mounted on the adaptive spectacles to switch to a power of +2 diopter via the control channel (e.g. Bluetooth®).

The above description, as well as some of the examples described herein below, describe helping people with presbyopia to view a close object in focus. Substantially the same systems and methods may also be implemented to provide myopia control and for relieving eye strain for people that do not suffer from presbyopia. In these cases, the adaptive spectacles reduce the amount of accommodation required by the person even though the person is capable of greater accommodation. Additionally, the systems and methods described herein may be implemented for eye testing to determine a prescription for vision correction. For example, optometrists may use a screen in the examination room (typically installed on a wall at least 3 meters away from the patient) while the patient is wearing adaptable spectacles. The patient, or optometrist, controls the optical power applied to the tunable lenses, and the optical center of the tunable lenses is automatically controlled so that the center of the tunable lenses is aligned with the line-of-sight between the patient and the screen. Similar tests can be conducted for determining a prescription for presbyopia with the patient (or optometrist) holding a mobile device 30-40 cm away from the patient's eyes while tuning the refractive power of the spectacles, and controlling the optical center of the tunable lens to be aligned automatically with the line-of-sight between the patient and the screen of the mobile device.

Laptop and desktop computers may utilize more powerful distance detection equipment such as a desktop eye tracker or desktop depth sensor (such as Microsoft's Kinect®) in order to correct for presbyopia. While the above applications are described to help people with presbyopia, it can be easily modified to handle eye-relief (performing partial or full refractive correction to reduce the need for human accommodation) or an eye therapy application described in more detail below.

Some people suffer from limited accommodation capability and can benefit from special therapy. Such therapy includes training sessions forcing the patient to accommodate—for example, by displaying a stereoscopic three-dimensional (3D) image on a 3D computer screen. These treatments also make use of refractive lenses aiming to shift the focal distance and challenge the patient's accommodation system. These treatments use continuous changes of the stimuli so as to trigger the patient's eyes to change their accommodation continuously for a certain amount of time, resulting in improvement of the accommodation capability. Such a system can be realized using the adaptive spectacles having electrically-tunable lenses in conjunction with a PC, mobile phone, or other computing platform running the session and controlling the adaptive spectacles either wirelessly or via a tethered connection. Eye therapy may also be implemented using a Virtual Reality (VR) headset, displaying the images at varying virtual distances, to trigger different accommodation reflex reactions, and controlling the adaptive spectacles (installed inside the VR headset) to change focus according to the treatment plan.

When driving, people have to continually change their vision focus from far distances, when looking at the road, to close distance when looking at the vehicle instrument panel (e.g., car gauges and other displays). For people with presbyopia, this is a difficult task and vision quality is poor. Embodiments of the present invention include installing a driver gaze detection system in the car (examples of such systems can be found in existing car and truck models—designed to detect and alert for driver fatigue or distraction). The gaze detection system may determine the relative position of the adaptive spectacles with respect to the vehicle instrument panel and communicate it, or focus and/or optical center information, to the adaptive spectacles. which then correct the driver's vision as needed.

When driving, for safety reasons, it may be beneficial to make sure a significant part of the lens, typically the top part, will constantly stay focused to far distance. In such cases, when the system identifies that the user requires vision correction for close distances, the positive lenses can be realized on only a part of the lens panel, for example using techniques described in the above PCT International Publication WO 2015/186010.

It should be noted that documents incorporated by reference herein are to be considered an integral part of the application except that, to the extent that any terms are defined in these incorporated documents in a manner that conflicts with definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.

System Description

Reference is now made toFIG.1A, which is a schematic, pictorial illustration of adaptive spectacles10being worn by a person11using a mobile device12, constructed and operative in accordance with an embodiment of the present invention.

The mobile device12includes a housing14, which is physically separate from the adaptive spectacles10. The mobile device12also includes, mounted in the housing14, a controller15, a display screen16, an interface, and a sensor19. The display screen16is configured to be viewed through the adaptive spectacles10by the person11. The interface17is configured to communicate with the adaptive spectacles10via a wired and/or wireless link18. The sensor19, possibly in conjunction with the controller15, is configured to detect a relative position20of the adaptive spectacles10with respect to the display screen16. The relative position may include an angular orientation of the adaptive spectacles10with respect to the display screen16and/or at least one distance between the adaptive spectacles10and the display screen16. The relative position may include detecting several predefined points on the adaptive spectacles10and/or detecting the adaptive spectacles10using machine learning techniques, by way of example only. The mobile device12is described in more detail below after the adaptive spectacles10are now described briefly.

Adaptive spectacles10comprise electrically-tunable lenses22and24, mounted in a spectacle frame25. The optical properties of the electrically-tunable lenses22and24, including focal length and an optical center27are controlled by control circuitry26, powered by a battery28or other power source. Control circuitry26typically comprises an embedded microprocessor with hard-wired and/or programmable logic components and suitable interfaces for carrying out the functions that are described herein. The adaptive spectacles10also include an interface30for communicating with an external system, such as the mobile device12. These and other elements of adaptive spectacles10are typically mounted on, or in, spectacle frame25, or may alternatively be contained in a separate unit (not shown) connected by wire to spectacle frame25.

The mobile device12is now described in more detail. The sensor19may include a front-facing camera (camera located on the display side of the mobile device12) disposed adjacent to the display screen16. The sensor19may either use a single or multiple aperture to determine depth (e.g., the distance between the adaptive spectacles10and the display screen16) with accompanying image-processing running on the controller15, and possibly other depth sensing components and techniques. In some embodiments, the sensor19may include a depth-sensor such as the depth sensor of Apple's iPhone® X. Other sensors such as accelerometers and gyroscopes disposed in the mobile device12and/or in the adaptive spectacles10may also provide information regarding the relative position. The accelerometers and gyroscopes may be implemented as part of an inertial measurement unit (IMU). In some embodiments, the interface17of the mobile device12is configured to receive an orientation reading (e.g., captured by an IMU of the adaptive spectacles10) from the adaptive spectacles10and the controller15is configured to correct the relative position based on the orientation reading. For example, some orientations of the adaptive spectacles10may be difficult to detect from the data captured by the sensor19. For these orientations, the orientations readings captured by sensor(s) of the adaptive spectacles10may be used by the controller15to correct the relative position.

The controller15is configured to receive an input signal from the sensor19. The input signal is indicative of the relative position of the adaptive spectacles10with respect to the display screen16. The controller15may be configured to determine the relative position of the adaptive spectacles10with respect to the display screen16based on image analysis of images captured by the sensor19(e.g., the front-facing camera) of the mobile device12. The relative position may include a distance from the display screen16to the adaptive spectacles10and/or an angular orientation of adaptive spectacles10with respect to the display screen16based on an appropriate coordinate system.

FIG.1Ashows three relative locations (X1,Y1,Z1and X2,Y2,Z2and X3,Y3,Z3) detected by the sensor19. The three relative locations shown inFIG.1Alocate the sides of the adaptive spectacles10(X1,Y1,Z1and X2,Y2,Z2) as well as an upper point (X3,Y3,Z3) of the adaptive spectacles10with respect to the display screen16. Appropriate selection of three relative locations is generally sufficient to identify an angular orientation of the adaptive spectacles10with respect to the display screen16and at least one distance between the adaptive spectacles10and the display screen16. Different points on the adaptive spectacles10may be similarly identified to identify the angular orientation of the adaptive spectacles10with respect to the display screen16and the distance(s) between the adaptive spectacles10and the display screen16. Although the example ofFIG.1Auses a Cartesian Coordinate system, any suitable coordinate system may be used. Using more than three locations may improve accuracy of the resulting calculation(s).

The distance between the display screen16and the adaptive spectacles10is generally sufficient to determine a focus adjustment to the electrically-tunable lenses22and24. The angular orientation (based on the relative location of three or more points) of the adaptive spectacles10with respect to the display screen16is generally also needed in order to determine an adjustment to the optical center(s)27of the electrically-tunable lenses22and24as will be described in more detail below. In some embodiments, the orientation of the adaptive spectacles10and the distance between the adaptive spectacles10and the display screen may be inferred from eye and/or head position.

The controller15may be configured to calculate, based on the relative position (e.g., distance from the display screen16to the adaptive spectacles10) and a given visual accommodation capability of the person wearing the adaptive spectacles10, at least one refractive power to which the electrically-tunable lenses22and24will be adjusted. It should be noted that only one, or both, of the electrically-tunable lenses22and24may be adjusted. If both of the electrically-tunable lenses22and24are to be adjusted, then each of the electrically-tunable lenses22and24will be adjusted to the same refractive power or different refractive powers. In some embodiments the at least one refractive power is calculated by the adaptive spectacles10as described below in more detail.

The following example illustrates how the refractive power of the electrically-tunable lenses22and24may be calculated. For a person with a limited accommodation of 1 diopter, the nearest point that can be seen clearly would be 1 m (100 cm) from the person's eyes. To see an object placed at 25 cm from the person's eyes would entail adjusting the refractive power of the electrically-tunable lenses22and24based on the lens formula (or based on diopter calculations):

1/focal length (f)=1/object distance (u)+1/image distance (v). Since the image formed is a virtual image, a minus sign is assigned to the image distance so the formula may be rewritten as 1/f=1/u−1/v. Substituting for the object distance of 25 cm and the image distance of 100 cm, 1/f=1/25−1/100. Hence f=100/3=33.3 cm which is equivalent of 100/33.3=3 diopters. The above calculation could be performed for each of the electrically-tunable lenses22and24separately resulting in a different correction for each of the electrically-tunable lenses22and24.

The controller15is configured to generate a command signal that is indicative of the calculated refractive power(s) to which the electrically-tunable lens(es)22,24will be adjusted. The given visual accommodation capability of the person wearing the adaptive spectacles10may be received by the mobile device12from the spectacles10in a set up stage or determined by the mobile device12in a configuration stage, for example, by asking the person11to hold the device and adjust the adaptive spectacles10until the person11indicates an image shown on the display screen16is being clearly seen by the person11.

Alternatively, the given accommodation capability of the person wearing the adaptive spectacles10may be stored by the adaptive spectacles10, which receives a signal indicative of the total required accommodation from the mobile device12. The spectacles10then calculates the refractive power(s) to which the electrically-tunable lens(es)22,24will be adjusted based on the given accommodation capability and the total required accommodation of the received signal.

Additionally, or alternatively, the controller15may be configured to calculate the optical center(s)27of the electrically-tunable lens(es)22,24based on the relative position of the adaptive spectacles10with respect to the display screen16so that a line-of-sight32of the person11wearing the adaptive spectacles10and viewing the display screen16is aligned with the optical center(s)27of the electrically-tunable lens(es)22,24when the electrically-tunable lens(es)22,24will be adjusted. The controller15is configured to generate the command signal to be indicative of the optical center(s)27of the electrically-tunable lens(es)22,24to which the electrically-tunable lens(es)22,24are to be adjusted in order to align the line-of-sight32of the person11wearing the adaptive spectacles10with the optical center(s)27of the electrically-tunable lens(es)22,24.FIG.1Ashows a first position29of the optical centers27of the electrically-tunable lenses22and24and a shifted, second position31, of the optical centers27calculated based on the person11looking sideways at the display screen16.

One method for calculating the optical center(s)27may be based on the normal vertex distance and the location of the center of rotation of the eye, as will now be explained. When the eye rotates in its orbit, there is a point within the eyeball that is more or less fixed relative to the orbit. This is the center of rotation of the eye. It may be considered, for convenience, that the center of rotation of the eye lies on the line-of-sight of the eye 13.5 mm behind the anterior pole of the cornea when the eye is in the straight-ahead position, that is when the line-of-sight is perpendicular to both the base line and the frontal plane. The vertex distance may be assumed to be 12 mm, which provides a total distance from the center of eye rotation to the back surface of the spectacle lens to be 25.5 mm. Geometric calculations may then be used, based on the relative position of the adaptive spectacles10with respect to the display screen16to calculate the optical center(s)27. The vertical and horizontal positions of the pupils captured in an image in a calibration stage may be used to provide X and Y positions (in the X-Y plane parallel to the plane of the electrically-tunable lenses22and24) of the centers of rotation of the eyes. One way of executing such a calibration is by capturing an image of the person wearing the spectacles while the person is looking straight ahead. Another way of executing the calibration is by capturing an image of the person wearing the adaptive spectacles10even while looking to the side and/or up or down. The spectacle frame25and the pupils of the person are identified in the captured image, and the coordinates of the center of rotation of each eye may then be calculated using geometric calculation, based on the location of the pupils in the image relative to the spectacle frame25, the dimensions of the spectacle frame25, and the estimation of the distance between the electrically-tunable lenses22and24and the center of rotation (e.g. 25.5 mm). The vertex distance may vary from spectacle to spectacle, but can generally be measured for any pair of adaptive spectacles10. The distance from the center of rotation of the eye to the anterior pole of the cornea may also vary between people. This distance may also be determined for the person11and used in the calculations or the assumed distance of 13.5 mm may be used instead.

In some embodiments, the controller15does not determine the refractive power and/or the optical center(s)27, but includes the relative position in the command signal for the adaptive spectacles10to determine the refractive power and/or the optical center(s)27based on the relative position. The command signal may be indicative of the relative position, for example, based on an image captured by the sensor19.

The controller15is configured to output, in response to the input signal, the command signal for sending to the adaptive spectacles10, via the interface17, for the adaptive spectacles10to adjust the focus aspect(s) of the electrically-tunable lens22,24.

In some embodiments, the controller15is configured to calculate the relative position periodically when it is estimated or determined that the person11wearing the adaptive spectacles10is using or viewing the display screen. The controller15may be configured to determine when the person11wearing the adaptive spectacles10is viewing the display screen16(e.g., based on eye gaze tracking), and/or using the display screen16(based on user interaction with a touch sensitive portion of the display screen16), and/or identifying movements of the mobile device12typically associated with using the display screen16such as movement in which the mobile device12is placed with the screen facing up using an inertial measurement unit, by way of example only. In response to determining that the person11wearing the adaptive spectacles10is viewing and/or using the display screen16, the controller15is configured to: determine the relative position; perform other calculations described above; and prepare the command signal, based on the relative position, for sending to the adaptive spectacles10to adjust the focus aspect(s) of the electrically-tunable lens(es)22,24.

The interface30of the adaptive spectacles10is configured to receive the command signal from the device12. If the command signal does not include the indication of the refractive power(s) to which the electrically-tunable lens(es)22,24should be adjusted, the control circuitry26of the adaptive spectacles10is configured to calculate, based on the relative position and the given visual accommodation capability of the person, the refractive power(s) to which the electrically-tunable lens(es)22,24will be adjusted. If the command signal does not include the indication of the optical center(s)27to which the electrically-tunable lenses22,24should be adjusted, the control circuitry26is configured to calculate the optical center(s)27of the electrically-tunable lens(es)22,24based on the relative position so that the line-of-sight32of the person11wearing the adaptive spectacles10, and viewing the display screen16, is aligned with the optical center(s)27of the electrically-tunable lens(es)22,24when the electrically-tunable lens(es)22,24will be adjusted.

The control circuitry26of the adaptive spectacles10is configured to adjust, based on the command signal, the focus aspect(s) of the electrically-tunable lens(es)22,24, such as the refractive power(s) of the electrically-tunable lens(es)22,24, and/or the optical center(s)27of the electrically-tunable lens(es)22,24to align the line-of-sight32of the person11wearing the adaptive spectacles10, and viewing the display screen16, with the optical center(s)27of the electrically-tunable lens(es)22,24.

Precise detection of viewing distance, from the adaptive spectacles10to the display screen16, by sensor19can be difficult and uncertain, and erroneous setting of the focal powers of lenses22and24can be disturbing to the person11wearing the adaptive spectacles10. To alleviate this problem, should it arise, the electrically-tunable lenses22and24may be set to different, respective focal powers that bracket a certain target distance that is estimated based on the sensor19. The lens power disparity takes advantage of the fact that binocular vision often requires only one eye to see a sharply-focused image in order for the view to seem focused. For example, if sensor19indicates that the target distance is 25 cm, for which electrically-tunable lenses22and24should be set to 3 diopters (relative to the person11normal refractive corrections), and the person11has a tolerance for defocus of 0.2 diopters, then control circuitry26may set electrically-tunable lenses22and24to respective powers of 2.8 and 3.2 diopters. This focal bracketing gives the person11the ability to see in focus over a wider range of distances (corresponding to powers of 2.6 to 3.4 diopters), in case the detected distance was not accurate.

The electrically-tunable lenses22and24can be operated with different optical powers at all times or only under certain circumstances in which the object distance is uncertain. The difference between the focal powers of the left and right lenses (0.4 diopters in the example above) can be constant or vary as a function of several parameters, such as the level of confidence in the object distance detected by sensor19; the probability distribution of the outputs of sensor19; lighting conditions; the detected distance itself; and/or the preferences of the person11.

In another embodiment, the electrically-tunable lens22and/or the electrically-tunable lens24may comprise two or more optical elements that apply different, respective focal powers to the incoming light that is incident on one or both of the eyes of the person11. These optical elements may be configured to refract light of different polarizations, for example by orienting the electro-optical layers in the elements in orthogonal directions. This embodiment is described further hereinbelow with reference toFIG.2. The electrically-tunable lenses22and24may be configured to operate on orthogonal polarizations in a similar manner.

As noted earlier, shifting the optical center27to the line-of-sight of the person11wearing the adaptive spectacles10may improve lens quality, particularly when the user is looking through an area near the edge of the lens. Erroneous shifts of the optical center27, however, can result in poor user experience. In one embodiment, control circuitry26overcomes this problem by applying a predefined time lag when shifting the optical center(s)27in response to changes in the relative position. The optical center(s)27of the electrically-tunable lens(es)22,24thus moves gradually in response to eye movements, until it reaches the optimal position. Gradual movements of the optical center(s)27that are slow enough not be noticeable by the person11may produce a more natural experience for the person11compared to abrupt lens shifts. The optical center(s)27of the electrically-tunable lenses22and24can be moved either simultaneously or consecutively, whether gradually or instantaneously in response to eye movements.

It should be noted thatFIG.1Ahas generally been described with reference to the mobile device12. The systems and/or methods described above may also be implemented using any suitable device, for example, but not limited to a laptop, or a PC with an external monitor and an external sensor.

Eye Therapy

As discussed above, some people suffer from limited accommodation capability and can benefit from special therapy. Such therapy includes training sessions forcing the patient to accommodate—for example, by displaying a stereoscopic 3D image on a 3D computer screen. These treatments also make use of refractive lenses aiming to shift the focal distance and challenge the patient's accommodation system. These treatments use continuous changes of the stimuli so as to trigger the patient's eyes to change their accommodation continuously for a certain amount of time, resulting in improvement of the accommodation capability. Such eye therapy may be implemented using the adaptive spectacles10in conjunction with a PC, mobile phone, tablet device or other computing platform running the eye therapy session and controlling the adaptive spectacles10either wirelessly or via a tethered connection.

The controller15or another processer (not shown) of the mobile device12is configured to execute an eye therapy software application to display a plurality of images on the display screen16. The plurality of images are generated to challenge a visual accommodation capability of the person11. The eye therapy software application is configured to determine a given visual accommodation capability to which the person11is to be challenged. Alternatively, the visual accommodation capability to which the person11is to be challenged may be determined by the person11or an eye therapist or other health professional. The controller15is configured to calculate at least one refractive power to which the electrically-tunable lens(es)22,24will be adjusted based on the relative position (based on the input from the sensor19) and the given visual accommodation capability to which the person11is to be challenged. The controller15is configured to prepare a command signal to include the refractive power(s) to which the electrically-tunable lens(es)22,24will be adjusted. The adaptive spectacles10are configured to adjust the refractive power(s) of the electrically-tunable lens(es)22,24according to the received command signal. Eye therapy may also be implemented using a VR headset, displaying the images at varying virtual distances, to trigger different accommodation reflex reactions, and controlling the adaptive spectacles10(installed inside the VR headset) to change focus according to the treatment plan.

In practice, some or all of the functions of the controller15may be combined in a single physical component or, alternatively, implemented using multiple physical components. These physical components may comprise hard-wired or programmable devices, or a combination of the two. In some embodiments, at least some of the functions of the processing circuitry may be carried out by a programmable processor under the control of suitable software. This software may be downloaded to a device in electronic form, over a network, for example. Alternatively, or additionally, the software may be stored in tangible, non-transitory computer-readable storage media, such as optical, magnetic, or electronic memory.

As mentioned above, the adaptive spectacles10may also be used to implement eye testing to determine a prescription for vision correction. For example, optometrists may use a display screen in the examination room (typically installed on a wall at least 3 meters away from the patient) while the patient is wearing the adaptive spectacles10. The patient, or optometrist, controls the optical power applied to the tunable lenses22,24, and the optical center of the tunable lenses22,24is automatically controlled so that the center of the tunable lenses22,24is aligned with the line-of-sight between the patient and the display screen. The optical power of the tunable lenses22,24may be controlled by the patient, or optometrist via a user input directly to the adaptive spectacles10or to the adaptive spectacles10via a remote device such as the mobile device12. The optical power of the tunable lenses22,24may be received by the controller15and/or the control circuitry26.

Similar tests can be conducted for determining a prescription for presbyopia with the patient (or optometrist) holding the mobile device12at a distance of 30-40 cm away from the patient's eyes while tuning the refractive power of the spectacles10, and controlling the optical center of the tunable lens22,24to be aligned automatically with the line-of-sight between the patient and the screen16of the mobile device12.

Vehicle Control

Reference is now made toFIG.1B, which is a schematic, pictorial illustration of the adaptive spectacles10ofFIG.1Abeing used while driving a vehicle33in accordance with another embodiment of the present invention.

As discussed above, when driving, people have to continuously change their vision focus from far distances, when looking at the road, to close distance when looking at a vehicle instrument panel37(e.g., car gauges and possibly one or more other display screens). For people with presbyopia, this is a difficult task and vision quality is poor.

The vehicle33includes a sensor34(performing a similar function to the sensor19ofFIG.1A), which may be implemented as part of a driver gaze detection system in the vehicle33. Examples of such systems can be found in existing car and truck models—designed to detect and alert for driver fatigue or distraction. The vehicle33includes an interface35and a controller36. The interface35and the controller36perform similar functions to the interface17and the controller15ofFIG.1A, respectively. The sensor34, generally in conjunction with the controller36, calculates the relative position of the adaptive spectacles10with respect to the vehicle instrument panel37. The controller36prepares a command signal for sending to the adaptive spectacles10via the interface35for the adaptive spectacles10to adjust the focus aspect(s) of the electrically-tunable lens(es)22,24. The focus aspect(s) may include a refractive power(s) and/or an optical center(s)38of the electrically-tunable lenses22and24as discussed in more detail above with reference toFIG.1A. The command signal is prepared in a similar manner as described above with reference toFIG.1A.

The refractive power(s) and the optical centers38of the electrically-tunable lens(es)22,24are generally adjusted if the controller36determines that the person11is looking down at the vehicle instrument panel37which may be based on the controller36analyzing an eye gaze direction of the person11captured by the sensor34or determining that part of the vehicle instrument panel37is being touched (e.g., a touch sensitive screen of the vehicle instrument panel37). Therefore, in response to the controller36determining that the person11wearing the adaptive spectacles10is viewing or using the vehicle instrument panel37, the controller36is configured to determine the relative position of the adaptive spectacles10with respect to the vehicle instrument panel37and prepare the command signal, based on the relative position, for sending to the adaptive spectacles10to adjust the focus aspect(s) of the electrically-tunable lens(es)22,24. In response to receiving the command signal via the interface30, the control circuitry26of the adaptive spectacles10is configured to adjust the refractive power(s) and the optical centers38of the electrically-tunable lens(es)22,24.

When driving, for safety reasons, it may be beneficial to make sure a significant part of the electrically-tunable lenses22and24, typically the top parts, will constantly stay focused to far distance. In such cases, when the controller36identifies that the person11requires vision correction for close distances, the positive lenses may be realized on only a part of the panels of the electrically-tunable lenses22and24, for example using techniques described in the above PCT International Publication WO 2015/186010.

Detailed Features of Electrically-Tunable Lenses

Reference is now made toFIG.2, which is a schematic side view of electrically-tunable lens22, in accordance with an embodiment of the invention. Lens24is typically of similar design.

In the pictured embodiment, lens22is a compound lens, which comprises multiple elements: A fixed lens40, typically made from glass or plastic, provides a baseline optical power, which is modified dynamically by two electrically-tunable lenses42and44. For this reason, lens22itself can be considered an electrically-tunable lens. Alternatively, lens22may comprise only a single electrically-tunable element, and fixed lens40may not be needed in some applications. In some embodiments, lens22also comprises a polarizing element46, such as a polarizer and/or polarization rotator, with functionality as described hereinbelow. The elements included in the lens22as shown inFIG.2may be positioned differently. For example, the polarizing element46may be positioned between tunable lens44and the eye, or alternatively farthest from the eye, on the outer surface of the fixed lens40. Furthermore, the fixed lens40can be divided into two fixed lenses, one positioned nearest to the eye and one positioned farthest from the eye, thus enclosing the tunable lenses42,44within the fixed lens.

Electrically-tunable lenses42and44adjust the optical power of lens22depending on the focal distance to the object being viewed by the user, while taking into account the considerations described in the preceding section. Additionally, or alternatively, an optical center48of lenses42and44may be shifted in response to changes in gaze direction32, as was likewise described above. Lenses42and44may comprise electrically-tunable cylindrical lenses, with orthogonal cylinder axes. Alternatively, lenses42and44may be configured, as shown inFIGS.3A-3D, to generate two-dimensional phase modulation profiles and thus emulate spherical or aspheric lenses (or their Fresnel equivalents). Both of these sorts of lens configurations, as well as waveforms for driving the lenses, are described in detail in the above-mentioned WO 2014/049577.

As noted earlier, in some embodiments in which lenses42and44comprise respective polarization-dependent electro-optical layers, the two lenses are oriented so as to refract mutually-orthogonal polarizations: One of these lenses, for example, lens42, operates on light polarized in the X-direction (pointing into the page in the view shown inFIG.2), and does not influence light polarized in the Y-direction (pointing upward in this view). Lens44operates on light polarized in the Y-direction, possibly with a different focal length from lens42, and does not influence light polarized in the X-direction. Unpolarized light passing through lenses42and44will thus be focused at both distances, with roughly half the light focused according to the focal length of lens42, while the other half is focused according to the focal length of lens44.

This solution may not work when there is polarized light in the optical path. In such a case, if the light is polarized in the same direction as one of lenses42and44, then all of the light will be focused according to the focal length of that lens.

To avoid this sort of polarization-dependence, in some embodiments polarizing element46comprises a polarization rotator, for example as described in the above-mentioned PCT publication WO 2015/186010, which intercepts the incoming light and rotates its polarization so as to ensure that the light incident on the electro-optical layers of lenses42and44has a component at each of the respective polarizations, regardless of the initial polarization of the intercepted light.

In some embodiments, the lens22may include two electrically-tunable cylindrical lenses42and two electrically-tunable cylindrical lenses44, with orthogonal cylinder axes, so that two of the lenses42are aligned with one common cylindrical axis and two of the lenses44are aligned with the other orthogonal cylindrical axis. Additionally, the lenses42include one lens which operates on light polarized in the X-direction and one which operates on light polarized in the Y-direction. Similarly, the lenses44include one lens which operates on light polarized in the X-direction and one which operates on light polarized in the Y-direction.

FIGS.3A-3Dschematically show details of electrically-tunable lens42in accordance with an embodiment of the present invention.FIG.3Ais a pictorial illustration of lens42, whileFIGS.3B and3Care side views showing transparent substrates52and54on opposing sides of an electro-optical layer50in lens42.FIG.3Dis a side view of device42, showing a superposition of excitation electrodes56and60that are located on substrates52and54on the opposing sides of lens42. Lens44may be of similar design. The lenses ofFIGS.2and3A-D are exemplary lenses which may be used with the adaptive spectacles10. Any other suitable electrically-tunable lenses may be used with the adaptive spectacles10.

Electro-optical layer50typically comprises a liquid-crystal layer, as described in the above-mentioned PCT International Publication WO 2014/049577. As explained above, layer50typically refracts light, in response to the voltage waveforms applied by electrodes56and60, in only one direction of polarization, while the other polarization passes through lens42without refraction. Alternatively, layer50may comprise a cholesteric liquid crystal or other electro-optical material that is polarization-independent.

Electrodes56and60on substrates52and54, respectively, comprise parallel stripes of transparent conductive material extending over the active area of layer50in mutually-orthogonal directions. Although electrodes56and60are of uniform shape and spacing in the figures, the stripes may alternatively have varying sizes and/or pitch. As shown inFIG.3D, the superposition of electrodes56and60creates an array of pixels64, defined by the areas of overlap of the vertical stripes of electrodes56with the horizontal stripes of electrodes60.

Control circuits58and62, under the control of control circuitry26or another controller, apply control voltages to excitation electrodes56and60, respectively. As described in the above-mentioned WO 2014/049577, the control circuits in lens42are able to modify the control voltages applied to each of a set of the excitation electrodes (which may include all of the electrodes) simultaneously and independently. Control circuits58and62together can modify the voltages applied to sets of the excitation electrodes on both of the sides of layer50, thereby modifying the phase modulation profile of the layer in two dimensions.

The control voltages applied to excitation electrodes56and60tune the focal properties of lens42, as determined by the phase modulation profile. Control circuits58and62can modify the control voltages so as to change the focal length and/or to shift the optical center of the lens. The voltage patterns applied by circuits58and62across electrodes56and60may be chosen so as to give a phase modulation profile that is circularly symmetrical, and may thus emulate a spherical or aspheric lens. Alternatively, different voltage patterns may be applied so that lens42functions, for example, as an astigmatic lens, with a stronger cylindrical component along one axis or the other.

Partitioned Dynamic Lenses

In some cases, it may be desirable to partition the area of an electrically-tunable lens, such as lenses22and24, into two independent lenses. For example, adaptive spectacles10may be configured so that in some scenarios, the lenses are partitioned, with part of the lenses set constantly for the user's vision correction to infinity, and the other part changing dynamically. Various examples that support optional spatial partitioning of the area of an electrically-tunable lens are described in the above-mentioned PCT publication WO 2015/186010. The lens in those examples can be operated as a single lens spanning over all (or at least part) of the active area, or the active area can be partitioned into two or more regions, each region implementing different lens characteristics (such as focal length and/or optical center). The lenses can be made to switch dynamically between these modes.

The present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the invention is defined by the appended claims and equivalents thereof.