HK1246867B - Controlling a lens for adjustable vision correction - Google Patents

Description

Control of lenses for adjustable vision correction

Technical Field

The invention relates to a device for controlling at least one lens for accommodative vision correction worn in front of an eye of a user of the device, a method thereof, a corresponding computer program and a corresponding computer program product.

Background Art

Presbyopia, the nearsightedness that occurs with aging, is quite common, affecting most people over the age of 45. When the human eye is functioning optimally, it can focus on objects ranging from approximately 25 centimeters to infinity. This is achieved by the ciliary muscle changing the shape of the lens inside the eye to maintain image focus on the retina at varying distances. With aging, the ciliary muscle's ability to deform the lens weakens, and the eye gradually loses its ability to focus on close objects.

Traditionally, presbyopia has been addressed by wearing additional lenses in front of the eyes, such as "reading glasses" for close viewing, or by integrating additional lenses into existing eyeglasses, such as "bifocals" or "varifocals." These additional lenses are accessed by glancing downward.

Recently, liquid crystal technology has been introduced for eyeglasses and contact lenses, which allows for controllable changes in refractive index by applying an electric field (see, for example, “Liquid crystal lens with large focal length tunability and low operating voltage,” by H. Ren, D. W. Fox, B. Wu, and S. T. Wu, Optics Express, vol. 15, no. 18, pp. 11328-11335, a publication of the Optical Society of America, 2007; “Electronic liquid crystal contact lenses for the correction of presbyopia,” by Osaka University Press, 2006). (The Optical Society Publications, 2014, pp. 8035-8040). This allows the optical properties of the lens to be controllably altered by applying a voltage or current. As described in US Pat. No. 6,517,203 B1, such lenses can be controlled by a manual switch or by using position sensors that detect when the wearer moves their head.

US 7,656,509 B2 proposes a device for determining the distance of an object that a user of electro-active lenses is viewing. The optical power of the electro-active lenses can be changed based on the determined distance, thereby ensuring that the object is correctly focused without requiring the user to operate a switch, glance down, or tilt their head.

Summary of the Invention

The object of the present invention is to provide an improved alternative to the above-mentioned technology and prior art.

More specifically, the object of the present invention is to provide an improved solution for controlling lenses for accommodative vision correction worn in front of the eyes of a user of a device, such as a mobile phone, smartphone, mobile terminal, tablet computer, e-book reader, computer screen or television.

These and other objects of the invention are achieved by the different aspects of the invention as defined in the independent claims. Embodiments of the invention are characterized by the dependent claims.

According to a first aspect of the present invention, a device for controlling at least one lens is provided. The lens is adapted to provide adjustable vision correction when worn in front of an eye of a user of the device. The device includes means operable to determine whether the user is looking at the device. If the user is looking at the device, the means is further operable to determine a distance between the eye and the device, and based on the determined distance, control the at least one lens to adjust its focal length.

According to a second aspect of the present invention, a method for controlling a device comprising at least one lens is provided. The lens is adapted for adjustable vision correction when worn in front of an eye of a user of the device. The method includes determining whether the user is looking at the device. The method further includes determining a distance between the eye and the device if the user is looking at the device, and controlling the at least one lens to adjust its focus based on the determined distance.

According to a third aspect of the present invention, a computer program is provided, comprising computer executable instructions which, when executed on a processing unit included in a device, cause the device to perform a method according to an embodiment of the second aspect of the present invention.

According to a fourth aspect of the present invention, there is provided a computer program product comprising a computer-readable storage medium containing the computer program according to the third aspect of the present invention.

Throughout this disclosure, the at least one lens is one or two contact lenses, or one or two lenses in a pair of glasses. The optical properties of the lens can be controlled and adjusted. Specifically, the refractive index of at least a portion of the lens can be adjusted by applying an electric field, voltage, or current. This allows the focal length of that portion of the lens to be adjusted.

Focal length is measured in metres and is the reciprocal of optical power, also known as inverted focal length, diopter, refractive power, focusing power or focusing power.

Lenses with electrically controllable focal lengths are often referred to as electro-active lenses and can be based on, for example, liquid crystal technology, which is known in the art. The lens can be controlled to adjust its focal length by switching between two or more states having different focal lengths. Alternatively, the focal length of the lens can be continuously adjustable.

The present invention is based on the understanding that adjustable vision correction lenses (e.g., electro-active lenses) worn by a user can be controlled by a device associated with the user. Specifically, the device can be a device that the user frequently or occasionally looks at, such as a mobile phone, smartphone, mobile terminal, tablet computer, e-book reader, computer screen, or television. Typically, such a device is located at a distance from the user, which may require the use of additional lenses such as reading glasses, bifocals, or varifocals, or the need to actively set the electro-active lenses worn by the user to a mode that, for example, if the user is presbyopic, is appropriate for the user's nearsighted state.

An advantage of embodiments of the present invention is that if the user is looking at a device, the electro-active lenses worn by the user are automatically controlled to adjust their focal length to a value suitable for correctly focusing on the device. For example, embodiments of the present invention can be used to correct presbyopia by compensating for the lack of ability to focus on closer objects if the user is looking at a device that is at a close distance. This is achieved by the device determining whether the user is looking at the device. If the user is looking at the device, the distance between the eye and the device is determined, and based on the determined distance, one or more electro-active lenses are controlled to adjust their focal length. In other words, the lenses worn by the user are only adjusted when necessary (i.e., when the user is looking at the device). Embodiments of the present invention alleviate the need for the user to actively operate a switch or move their head to adjust the focal length of their lenses.

The solutions described herein are advantageous over known electro-active lenses, which adjust based on the distance to the object the user is viewing, as determined by a distance meter integrated with the lens. Lenses used with embodiments of the present invention are lighter and can be manufactured at a lower cost, as distance-measuring devices are quite complex and often too complex to be integrated with contact lenses. In other words, rather than relying on integrating the distance-measuring and/or gaze-detection capabilities of the electro-active lens into a contact lens or eyeglass frame, embodiments of the present invention rely on the device being gazed at by the user. This is particularly advantageous for devices that are operated and/or held by the user's hand, as the distance between the eye and the device is limited by the user's anatomy (i.e., the user's arm).

According to an embodiment of the present invention, at least one lens is controlled to adjust its focus based on information related to an eye disease or condition of the user, such as presbyopia, hyperopia (farsightedness), or myopia (nearsightedness). This information can be obtained from the user's prescription, medical records, a database maintained by the lens manufacturer, or the like. The information can be provided by the user, retrieved via the internet, or received from the lens, for example, via a communication link between the device and the lens. To retrieve the information, the lens, a batch of lenses, and/or the user are preferably identified in the request for retrieving the information. The information can also relate to a threshold distance indicating a transition between a nearsighted state and a farsighted state of the user's eye, as described below.

According to one embodiment of the present invention, the determined distance is compared with a threshold distance representing a transition between a myopic state and a hyperopic state of the eye. For example, presbyopia becomes apparent in the myopic state. If the determined distance is below the threshold distance, at least one lens is controlled to adjust its focal length to a focal length suitable for the myopic state. Alternatively, if the determined distance is equal to or above the threshold distance, at least one lens is controlled to adjust its focal length to a focal length suitable for the hyperopic state. Controlling the lens to switch between the myopic state and the hyperopic state is particularly suitable for lenses that can switch between two different focal lengths. For example, known liquid crystal-based lenses have a reduced focal length when activated, making them suitable for correcting presbyopia in the activated state.

The threshold distance may be configured by the user based on the characteristics of the lenses (e.g., recommended by the lens manufacturer) or based on the user's prescription. Alternatively, the threshold distance may be obtained by detecting the distance at which the user holds the device to comfortably read. For example, the device may detect that the user extends her arm whenever she reads small-font text. It will also be appreciated that based on detecting that the user extends her arm and the distance at which she holds the device when attempting to read small-font text, the device may detect a condition for the onset of presbyopia. If the distance gradually increases over time, a condition for the onset of presbyopia may exist, and the user may optionally be informed.

According to one embodiment of the present invention, if the user is not looking at the device, at least one lens is controlled to adjust its focal length to a focal length appropriate for the eye's hyperopia state. In other words, if the user is not looking at the device, it is assumed that the user is looking at an object at a distance comparable to hyperopia. For example, known liquid crystal-based lenses are suitable for hyperopia when not activated.

According to one embodiment of the present invention, the distance between the eye and the device is determined by detecting that the device is held and/or operated by the user's hand and determining the distance based on the user's anatomy. That is, the distance is inferred based on the understanding that the user's anatomy (particularly the length of her arms) and her habit of holding the device limit the distance between the eye and the device to a certain range. Optionally, if the distance thus determined is below a threshold distance representing a transition between a myopic state and a hyperopic state of the eye (as described above), then in response to detecting that the device is held and/or operated by the user's hand, the lens can be controlled to adjust its focal length to a focal length suitable for the myopic state. Advantageously, detecting that the device is held and/or operated by the user's hand is simpler than determining the distance using solutions based on structured light, time-of-flight cameras, image processing with perspective zoom, or other types of distance-measuring devices, as will be further described below.

According to one embodiment of the present invention, if the device is being operated by the user's hand, it is determined that the user is looking at the device. That is, if the user is touching the touchscreen of a smartphone or pressing a button on the phone, it is inferred that they are looking at the device. Advantageously, detecting that the user is operating the device with their hand is simpler than other solutions for gaze detection or eye tracking, such as image processing, as will be described further below.

According to one embodiment of the present invention, the user, the lens, or both are identified. This is advantageous because a user may want to ensure that only devices under their control can control the lenses they are wearing. This prevents any nearby devices (such as a friend's television or a tablet operated by someone sitting next to the user) from controlling the user's lenses. The user can be identified based on facial recognition, i.e., by image processing an image captured by a camera, such as a smartphone or tablet's front-facing camera. The lens can be identified by wirelessly retrieving information from the lens via a communication link. For example, the lens can transmit an identifier to the device, such as an identifier for the lens, a batch of lenses, or information identifying the user to whom the lens is assigned. As an alternative to or in addition to information identifying the lens, the device can receive information about the lens' optical properties from the lens. Optionally, the lens is controlled to adjust its focus only if the user and/or lens are successfully identified.

According to one embodiment of the present invention, if the user is not looking at the device, an object around the device that the user is looking at is determined, the distance between the eye and the object is determined, and based on the determined distance, at least one lens is controlled to adjust its focus. This can be implemented based on any known gaze detection, eye tracking, and distance measurement devices, as will be further explained below. Advantageously, devices such as smartphones, mobile terminals, and tablets can be used to control one or more lenses worn by a user even when the user is not looking at the device, but rather looking at an object (such as a television, a person, a wall, etc.).

Although advantages of the invention have been described in some cases with reference to embodiments of the first aspect of the invention, corresponding reasoning applies to embodiments of the other aspects of the invention.

Other objects, features and advantages of the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims.Those skilled in the art appreciate that different features of the present invention can be combined to form embodiments other than those described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will be better understood through the following illustrative and non-limiting detailed description of embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 illustrates a user gazing at different objects according to an embodiment of the present invention.

FIG. 2 illustrates spectacles for adjustable vision correction according to an embodiment of the present invention.

FIG. 3 illustrates a contact lens for accommodative vision correction according to an embodiment of the present invention.

4a and 4b illustrate an apparatus for controlling lenses for adjustable vision correction according to an embodiment of the present invention.

FIG. 5 illustrates a method of controlling lenses for accommodative vision correction according to an embodiment of the present invention.

FIG6 illustrates processing modules for controlling an apparatus for adjustable vision correction lenses according to an embodiment of the present invention.

FIG. 7 illustrates a processing module for controlling an apparatus for adjustable vision correction lenses according to other embodiments of the present invention.

All the figures are schematic and not necessarily to scale and generally only show parts which are necessary in order to elucidate the invention, wherein other parts may be omitted or merely suggested.

DETAILED DESCRIPTION

The present invention will now be described more fully with reference to the accompanying drawings, in which certain embodiments of the invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art.

FIG1 shows a user 110 looking at various objects and devices. For example, user 110 may be looking at 171 her smartphone 120 while reading a webpage or typing an email. Alternatively, user 110 may be looking at 172 a book 120 she is reading, or she may be looking at 173 a television 140. User 110 is shown wearing glasses 150 in front of her eyes 112, for example, to correct an eye disease or condition such as presbyopia, hyperopia (farsightedness), or myopia (nearsightedness).

Referring to FIG2 , glasses 150 are shown in greater detail, assuming that at least one lens 151 included in glasses 150 has an adjustable focal length within at least a portion 152 of lens 151. Lenses with an adjustable focal length are also known as electro-active lenses and can, for example, be based on a liquid crystal layer disposed on an underlying lens having a focal length f _0. When activated, the focal length of lens 151 is adjusted to a value f ₀ + Δf using an electric field, voltage, or current applied to or through the liquid crystal layer, where the focal length change Δf is due to a change in the refractive index of the liquid crystal layer. As an example, lens 151 can include a liquid crystal layer such that, when the liquid crystal layer is activated by applying an electric field, voltage, or passing a current through it, the focal length f ₀ + Δf decreases from its value f ₀ in the inactive state. Thus, lens 151 is suitable for correcting presbyopia when activated.

It should be understood that embodiments of the present invention are not limited to liquid crystal-based lenses. Rather, embodiments of the present invention may utilize any type of lens with a controllable focal length. Furthermore, as an alternative to glasses 150 comprising lens 151, embodiments of the present invention may also utilize an electrically activated contact lens 351 having an adjustable focal length within at least a portion 352 of the contact lens 351, as shown in FIG3 .

2 , the glasses 150 are shown as including a lens control unit 153 integrated into the frame of the glasses 150. The lens control unit 153 is operable to receive control signals transmitted by a device for controlling at least one lens for adjustable vision correction (according to one embodiment of the present invention) or a remote control unit 180 (described below). It will be understood that the lens control unit 153 can include analog or digital electronic circuitry, or a combination thereof, depending on the technology used to transmit and receive control signals. Alternatively, the lens control unit 153 can be integrated into one or more lenses 151, similar to the lens control unit 353 integrated into the contact lens 351 shown in FIG3 .

In the following, an embodiment of a device for controlling at least one lens for adjustable vision correction worn in front of the eyes of a user of the device is described with further reference to Figures 4a and 4b. In these figures, the device 120 is exemplified as a smartphone. For simplicity, the embodiment of the present invention is described as controlling one lens 151 of glasses 150. However, corresponding embodiments for controlling two lenses 151 of glasses 150 or one or two contact lenses 351 can also be easily envisioned.

In Figure 4a, user 110 is shown holding and operating device 120 with hand 111. Device 120 comprises a display 121 (such as a touch screen) which user 110 is looking at 411, and a processing module 123 which is described in further detail below with reference to Figures 6 and 7.

The device 120 is operable to determine whether the user 110 is looking 411 at the device 120. If it is determined that the user 110 is looking 411 at the device 120, the distance between the eye 112 of the user 110 and the device 120 is determined, and based on the determined distance, the lens 151 is controlled to adjust its focus. For clarity, it should be noted that the distance between the eye 112 and the device 120 corresponds to the length of the dashed line 411 shown in FIG. 4 a.

The device 120 may be operable to determine whether the user 110 is looking at the device 120 in a variety of ways. For example, the device 120 may include a front-facing camera 122 and a processing module 123 operable to acquire an image from the camera 122 and determine 411 whether the user 110 is looking at the device 120 based on image processing, as is known in the art (see, for example, “Noncontact Binocular Eye-Gaze Tracking for Point-of-Gaze Estimation in Three Dimensions,” by C. Hennessey and P. Lawrence, IEEE Transactions on Biomedical Engineering, Vol. 56, No. 3, March 2009). Alternatively, the gaze of the eye 112 may be determined based on any other known eye tracking technique, such as by detecting infrared light reflected by the eye 112 and sensed by the camera 122, by tracking the corneal reflection (first Purkinje image) and the pupil center of the eye 112 over time using images periodically acquired from the camera 112, or by tracking the reflection from the front of the cornea (first Purkinje image) and the back of the lens of the eye 112 (fourth Purkinje image) over time.

As another alternative, if it is detected that the device 120 is being operated by the user 110, the device 120 may be operable to determine that the user 110 is looking at the device 120 411. For example, it may be detected that a finger of the hand 111 or another finger is touching the touch screen 121 or a button (not shown in FIG. 4 a ) provided with the touch device 120. In other words, it is inferred that the user 110 may be looking at the device 120 while actively operating it 411.

The device 120 may be operable to determine the distance between the eye 112 and the device 120 using a variety of different techniques. For example, the device 120 may be operable to determine the distance by using structured light (i.e., by projecting a known light pattern) and by detecting light reflected by objects in the surrounding environment (such as the head, face, or eye 112 of the user 110). This can be achieved without the user 110 noticing by using infrared light. Alternatively, the device 120 may be provided with a time-of-flight camera 122 that is capable of measuring the time of flight of light emitted by the device 120 and reflected by the head, face, or eye 112 of the user 110 and detected by the camera 122. Another alternative for determining the distance between the eye 112 and the device 120 is image processing combined with perspective zooming. Additionally, technologies for gesture recognition, such as Microsoft's Kinect and Intel's RealSense, or radio frequency radars such as Google's Soli, may also be utilized.

As yet another alternative, the distance between eye 112 and device 120 can be determined by detecting that device 120 is being held and/or manipulated by a hand of user 110 (e.g., hand 111) and determining the distance based on user 110's anatomy (such as arm length) and, optionally, their habit of holding device 120. Advantageously, this is less complex than the aforementioned solution and can be implemented by utilizing touchscreen 121 or any other touch-sensitive or pressure-sensitive surface of device 120. Alternatively, if device 120 is detected to be held and/or manipulated by a hand of user 110, device 120 may use a default value distance as the distance between eye 112 and device 120. For example, such a default value may be configured by user 110. Using a default value as the distance between eye 112 and device 120 is particularly advantageous if the distance is below a threshold distance that indicates a transition between a nearsighted state and a farsighted state for one or both eyes 112, as described further below. In this case, in response to detecting that the user 110 is looking 411 at the device 120, the device 120 may be operable to control the lens 151 so as to adjust to a focal length suitable for the myopic state of the (two) eyes 112, without having to determine the distance based on actual measurement using one of the above-mentioned techniques.

The device 120 is further operable to, after determining the distance between the eye 112 and the device 120, control the lens 151 to adjust its focal length based on the determined distance by measuring the distance or inferring the distance based on detecting that the device 120 is held and/or operated by the hand of the user 110. The lens 151 can be controlled to adjust its focal length by switching between at least two states having different focal lengths. Alternatively, the focal length of the lens 151 can be continuously adjustable.

The device 120 may also be operable to adjust the focal length of the lens 151 based on information related to an eye disease or condition of the user 110 (e.g., presbyopia). An example of such information is, for example, a threshold distance representing a transition between a nearsighted state and a farsighted state for one or both eyes 112, or information obtained from the user's 110 prescription. This information may be provided by the user 110, received from the lens 151 via a wireless communication link, or retrieved over the Internet, for example, from a database provided by the lens manufacturer. To retrieve information from the database, the lens 151, a batch of lenses, or the user 110 is preferably identified in the request for retrieving the information.

Device 120 may further be operable to compare the determined distance to a threshold distance representing a transition between a nearsighted state and a farsighted state for the eye(s) 112. In this case, if the determined distance is below the threshold distance, lens 151 is controlled to adjust its focal length to a focal length suitable for the nearsighted state, as presbyopia becomes apparent in the nearsighted state. Controlling lens 151 to switch between the nearsighted state and the farsighted state is particularly suitable for electrically activated lenses that are switchable between two different focal lengths. For example, the known liquid crystal-based lenses described above decrease in focal length upon activation, making them suitable for correcting presbyopia in the activated state.

The threshold distance can be configured by user 110 based on the characteristics of lens 151, such as a recommendation from a lens manufacturer or based on user 110's prescription. Alternatively, the threshold distance can be obtained by detecting the distance at which user 110 holds device 120 for comfortable reading. For example, device 120 can be operable to detect that user 110 extends her arm whenever reading small-font text, and determine the distance between eye 112 and device 120 when adjusted to allow comfortable reading. If the distance thus determined gradually increases over time, this can also be used to detect the onset of presbyopia. In this case, user 110 can be informed that she may be suffering from presbyopia.

Alternatively, if the determined distance is equal to or greater than a threshold distance, device 120 may be further operable to control lens 151 to adjust its focal length to a focal length appropriate for a hyperopia state. This may occur, for example, if device 120 is located further away from user 110 (e.g., a tablet computer placed on a table in front of user 110, or television 140 as shown in FIG. 1 ).

If the user is not looking at device 120, device 120 may be further operable to control lens 151 to adjust its focus to a focus appropriate for the hyperopia state of eye(s) 112, as shown in FIG4 b. That is, if user 110 is not looking at device 120, it is assumed that she is looking at an object at a distance commensurate with the hyperopia state of eye(s) 112. For the aforementioned liquid crystal-based lenses, the hyperopia state corresponds to an inactive state of the liquid crystal layer.

The focal length suitable for the nearsighted state of the eye 112 and the focal length suitable for the farsighted state of the eye 112 can be predetermined values 110 configured by the user 110, the lens manufacturer, or derived from the user's prescription. Specifically, the respective values of the focal lengths in the nearsighted state and the farsighted state can correspond to two different focal lengths supported by the lens 151.

The device 120 may be operable to control the lens 151 by transmitting a control signal to adjust its focal length. For example, the control signal may be transmitted by a radio module 124 supporting a wireless communication technology such as Bluetooth, wireless local area network (WLAN)/WiFi, or a cellular standard, in particular in accordance with the Third Generation Partnership Project (3GPP) technical specifications. Alternatively, the radio module 124 may utilize near-field technology such as radio frequency identification (RFID). As yet another alternative, the device 120 may be operable to use the display 121 to emit coded light, in particular visible coded light. The communication link established between the radio module 124 and the lens 151 or the lens control unit 153 may also be used to exchange information identifying the user 110 and/or the lens 151 or information related to the optical properties of the lens 151.

The control signal may be transmitted as a message containing one or more information elements. The control signal, message, or one or more information elements may include information indicating at least one of the following: the determined distance, the target focal length of the lens 151, and the target state of at least two states of the lens 151 having different focal lengths. Alternatively, the control signal may switch the lens 151 between two states having different focal lengths (e.g., between an inactive state and an active state). The radio module 124 may also be operable to transmit control signals of different frequencies, each frequency being associated with one of the at least two states of the lens 151. Furthermore, if no control signal is received, the lens 151 may be operable to assume a first state, such as an inactive state of the liquid crystal layer, and a second state, such as an active state of the liquid crystal layer, if a control signal is received. In this case, if the distance is determined to be below a threshold distance, the device 120 may be operable, for example, to transmit a control signal via the radio module 124 to control the lens 151 to assume a state having a focal length corresponding to the myopia state of the eye(s) 112, as long as the user 110 is looking at the device 120. Advantageously, the potential, voltage or current required to activate the lens 151 can be obtained from the received control signal, as is known in RFID technology.

Alternatively, rather than transmitting the control signal directly to the lens control unit 153 included in the glasses 150 or the lens control unit 353 included in the contact lens 351, respectively, the control signal may be transmitted to a remote control unit 180 worn by the user 110. The remote control unit 180 includes a processing module 181, a first radio module 182 for communicating with the device 120, and a second radio module 183 for communicating with the lens 151. By transmitting the second control signal via the second radio module 183, the remote control unit 180 is operable to control the lens 151 based on the control signal received via the first radio module. Using the remote control unit 180 to control the focus of the lens 151 is advantageous because it can be positioned closer to the lens 151 than the device 120, thereby facilitating the use of short-range technologies (such as RFID) to control the lens 151 via the second control signal. This increases the power received by the lens control unit 153, which is advantageous for embodiments that rely on energy harvested from the received control signal to activate the lens 151.

The functionality described herein can also be distributed between the device 120 and the remote control unit 180. For example, the device 120 can be operable to transmit only the determined distance, while the remote control unit 180 can be operable to compare the determined distance to a threshold distance, etc. In other words, the remote control unit 180 can receive information independent of the optical properties of the lens 151 and/or the eye condition of the user 110, and generate the second control signal based on the optical properties of the lens 151 and/or the information related to the eye condition of the user 110.

4 b , if it is detected that user 110 is not looking at device 120 but is looking 412 in a different direction, device 120 may be further operable to determine an object around device 120 that user 110 is looking at, determine the distance between eye 120 and the object, and control lens 151 to adjust its focus based on the determined distance. For example, as shown in FIG1 , device 120 may detect that user 110 is looking 172 at book 130 or looking 173 at television 140.

Although an embodiment of a device for controlling at least one lens for adjustable vision correction has been described in conjunction with the smart phone 120 shown in Figure 1, it will be understood that corresponding embodiments can be envisioned for other types of devices, such as a mobile phone, a mobile terminal, a tablet computer, an e-book reader, a computer screen or a television (such as television 140).

If user 110 has multiple devices (e.g., smartphone 120 and television 140), they can control lens 151 independently or collaboratively. For example, if each device has detected that user 110 is looking at it, each device can independently send a control signal to lens 151. Alternatively, the devices can collaboratively determine the object user 110 is looking at and/or the distance between eye 112 and the object. For example, the distance can be determined based on a 3D image generated from a 2D image captured by a camera equipped with the device (e.g., front camera 122 of smartphone 120 and camera 142 of television 140). Alternatively, one or more devices can be operable to emit structured light and detect light reflected from objects in the surrounding environment. As yet another alternative, device 120 can include a rear camera in addition to front camera 122, and can determine the object user 110 is looking at and the distance between eye 112 and the object by performing image processing on images captured by front camera 122 and rear camera.

In a scenario involving multiple devices, one of the devices, such as the smartphone 120 , can act as a master device that transmits control signals to the lens 150 based on information such as the distance to one or more objects, the gaze of the eye 112 , or images received from other devices (e.g., from a television 140 ).

To further illustrate the invention, an embodiment of a method of controlling a device 120 for accommodating at least one lens 151 for vision correction will now be described with reference to Figure 5. The device may be, for example, a mobile phone, a smartphone, a mobile terminal, a tablet, an e-book reader, a computer screen or a television.

Method 500 includes determining 503 whether a user is looking at device 120, and if 504 the user is looking at device 120, determining 505 the distance between eye 112 and device 120, and based on the determined distance, controlling 507 lens 151 to adjust its focal length. Preferably, lens 151 is controlled by transmitting 507 a control signal to lens 151 to adjust its focal length. The control signal is transmitted to lens 151 or glasses 150 including the lens, or to a lens control unit 153 included therein, or to a remote control unit 180 operable to control lens 151. The control signal may include information representing at least one of the following: the determined distance, a target focal length from which 506 may be optionally derived, and a target state of at least two states of lens 151 from which 506 may be optionally derived, wherein the at least two states have different focal lengths.

Optionally, the lens 151 is controlled to adjust its focus further based on information related to an eye disease or eye condition of the user 110. Such information may be obtained, for example, from the lens 151 or from a database search 502. The method 500 may optionally include identifying 501 the user 110 and/or the lens 151.

The target focal length or target state can be derived 506, for example, by comparing 511 the determined distance with a threshold distance representing a transition between a near-vision state and a far-vision state of the (two) eyes 112, wherein if the determined distance is below 511 the threshold distance, the lens 151 is controlled to adjust its focal length to a focal length suitable for the near-vision state 512. Alternatively, if the determined distance is equal to or greater than 511 the threshold distance, the lens 151 is controlled to adjust its focal length to a focal length suitable for the far-vision state 513.

Optionally, if it is determined 504 that the user 110 is not looking at the device 120 , the method 500 may further comprise controlling at least one lens to adjust its focal length to a focal length 521 suitable for the hyperopic state of the eye(s) 112 .

For example, the distance between the eye 112 and the device 120 may be determined by detecting that the device 120 is held and/or operated by the hand 111 of the user 110 and determining the distance based on the body structure of the user 110 .

Alternatively, it may be determined 504 that if the device 120 is being operated by the hand 111 of the user 110 , then the user 110 is looking at the device 120 .

Furthermore, if the user is not looking 504 at the device 120 , the method 500 may optionally include determining 531 an object around the device 120 that the user 110 is looking at, determining 532 a distance between the eye 112 and the object, and based on the determined distance, controlling 507 the lens 151 to adjust its focus.

The method 500 may further include additional or alternative steps according to embodiments of the present invention described throughout this disclosure, particularly with reference to FIG. 1 to FIG. 4 ,

In Figure 6, an embodiment 600 of the processing module 123 included in the device 120 is shown. The processing module 600 includes a processing unit 601 (such as a general purpose processor) and a memory 602. The memory 602 includes computer executable instructions 603. As described above, the processing module 600 may optionally include one or more interfaces 604 ("I/O" in Figure 6) for communicating with the touch screen 121, the camera 122, and the radio module 124. When executed on the processor 601, the computer executable instructions cause the device 120 to perform embodiments of the present invention, in particular, an embodiment of the method 500 with reference to Figure 5. More specifically, the device 120 is operable to determine whether the user 110 is looking at the device 120, and if the user 110 is looking at the device 120, determine the distance between the eye 112 and the device 120, and based on the determined distance, control the lens 151 to adjust its focus. In addition, the device 120 may be operable to perform additional or alternative functions described throughout this disclosure.

An alternative embodiment 700 of the processing module 123 is shown in Figure 7. The processing module 700 includes a gaze module 701 for determining whether the user 110 is looking at the device 120, a distance module 702 for determining the distance between the eye 112 and the device 120 if the user 110 is looking at the device 120, and a control module 703 for controlling the lens 151 to adjust its focus based on the determined distance. The processing module 700 may include additional or alternative modules that are operable to implement the functionality described throughout this disclosure, such as a user/lens identification module 704 for identifying the user 110 and/or the lens 151, and/or a lens/eye information module 705 for providing information related to an eye disease or eye condition of the user 110 and/or the optical properties of the lens 151.

Embodiments of the apparatus for controlling at least one lens for adjustable vision correction, and in particular embodiments of the processing modules 600 or 700, may be implemented by any suitable combination of software executed on a processor or hardware, such as analog or digital electronics, integrated circuits (ICs), application specific integrated circuits (ASICs), etc. It will be understood that the specific functional modules shown in Figures 6 and 7 are merely examples, and embodiments of the apparatus and processing modules may use any suitable combination of functional modules in addition to those described herein and shown in Figures 6 and 7.

It will be appreciated by those skilled in the art that the present invention is by no means limited to the embodiments described above, but rather that numerous modifications and variations are possible within the scope of the appended claims.

Claims (20)

1. A device (120, 140) for controlling at least one lens (151; 351) for adjustable vision correction worn in front of the eye (112) of a user (110) of the device, said device comprising means (121-124; 142; 600; 700) operable to: Determine whether the user is looking at (411) the device, and If the user is looking at the device: The distance between the eye and the device is detected based on signals emitted from the device to the user; Based on the detected distance, a threshold distance representing the transition between myopia and hyperopia in the eye is determined; and When the threshold distance is detected to increase over time, it is determined that the user (110) may have presbyopia. 2. The device (120, 140) according to claim 1, the device is further operable to notify the user (110) that they may have presbyopia. 3. The device (120, 140) according to claim 1, wherein the device is further operable to determine the threshold distance by detecting that the user (110) extends his arm while reading small-font text, and determining the distance between the eyes (112) and the device (120) when adjusted to a comfortable reading position. 4. The device of claim 3, wherein the means is further operable to compare the determined distance with the threshold distance, wherein if the determined distance is lower than the threshold distance, the at least one lens is controlled to adjust its focal length to a focal length suitable for the myopia state. 5. The device of claim 4, wherein if the determined distance is equal to or greater than the threshold distance, the at least one lens is controlled to adjust its focal length to a focal length suitable for the hyperopia state. 6. The device according to any one of claims 1 to 5, wherein if the user is not looking at (412) the device, the device is further operable to control the at least one lens to adjust its focal length to a focal length suitable for the farsighted state of the eye. 7. The device according to any one of claims 1 to 5, wherein the device is a mobile phone. 8. The device according to any one of claims 1 to 5, wherein the device is a smartphone (120). 9. The device according to any one of claims 1 to 5, wherein the device is a mobile terminal. 10. The device according to any one of claims 1 to 5, wherein the device is a tablet computer. 11. The device according to any one of claims 1 to 5, wherein the device is an e-book reader. 12. The device according to any one of claims 1 to 5, wherein the device is a computer screen. 13. The device according to any one of claims 1 to 5, wherein the device is a television set (140). 14. A method (500) of a device for controlling at least one lens (151; 351) for adjustable vision correction worn in front of the eye (112) of a user (110) of the device, the method comprising: Determine whether the user is looking at (411) the device, and If the user is looking at the device: The distance between the eye and the device is detected based on signals emitted from the device to the user; Based on the detected distance, a threshold distance representing the transition between myopia and hyperopia in the eye is determined; and When the threshold distance is detected to increase over time, it is determined that the user (110) may have presbyopia. 15. The method of claim 14, further comprising notifying the user (110) that they may have presbyopia. 16. The method of claim 14, further comprising determining the threshold distance by detecting that the user (110) extends his arm while reading small-font text, and determining the distance between the eyes (112) and the device (120) when adjusted to a comfortable reading position. 17. The method according to any one of claims 14 to 16, further comprising: comparing the determined distance with the threshold distance, and if the determined distance is lower than the threshold distance, controlling the at least one lens to adjust its focal length to a focal length suitable for the myopia state. 18. The method of claim 17, further comprising: if the determined distance is equal to or greater than the threshold distance, controlling the at least one lens to adjust its focal length to a focal length suitable for the hyperopia state. 19. The method according to any one of claims 14 to 16, further comprising: if the user is not looking at (412) the device, controlling the at least one lens to adjust its focal length to a focal length suitable for the farsighted state of the eye. 20. A computer-readable storage medium (602) having a computer program (603) thereon storing computer executable instructions that, when executed on a processing unit (601) included in a device, cause the device to perform the method according to any one of claims 14 to 19.