Privacy enhancement system comprising eyewear and display device

Abstract

There is provided an eyewear for privacy enhancement. The eyewear comprises a support structure. The eyewear comprises at least one lens. The at least one lens is held by the support structure. The at least one lens comprises a transparent layer of metamaterial. The metamaterial comprises a structure in which incident light of a first infrared wavelength and incident light of a second infrared wavelength interfere to, through an optical process, produce outgoing light in a visible wavelength. The eyeware also comprises a power supply. The eyewear further comprises an infrared light source powered by the power supply, wherein the infrared light source is held by the support structure, and is tunable to emit light in the first or second infrared wavelength into the metamaterial.

Description

[0001] PRIVACY ENHANCEMENT SYSTEM

[0002] COMPRISING EYEWEAR AND DISPLAY DEVICE

[0003] TECHNICAL FIELD

[0004] Embodiments presented herein relate to an eyewear, a display device, and a privacy enhancement system comprising the eyewear and the display device.

[0005] BACKGROUND

[0006] In general terms, using electronic devices in public spaces, such as airports, cafes, or coworking spaces, might result in sensitive information, such as financial information, passwords, trade secrets, company documents, personal information or personal conversation, as displayed on screens being exposed to eavesdroppers. One object of protecting screen content from causal viewing is therefore to prevent identity theft, corporate espionage, or other security breaches.

[0007] Further, causal viewing of screen content by others can be distracting and undermine productivity, particularly in shared office spaces or other collaborative environments. By shielding screen content from view, individuals can maintain focus on their work without being interrupted or concerned about onlookers.

[0008] One technology to overcome the abovementioned issues is to adjust the screen brightness or placement of displayed objects (such as documents) to make it more difficult for eavesdroppers to view the display content. A further technology is to run a privacy software application, where content of specific windows on the screen can be hidden and visible again on demand. However, these technologies still run the risk of making sensitive content possible to be viewed by an eavesdropper.

[0009] Some other, potentially more effective, existing technologies that provide varying levels of screen content protection will be summarized next.

[0010] By extracting the outer polarization layer from a liquid-crystal display (LCD) device and integrating it into a pair of glasses, a unique display is created that can only be viewed using specialized, i.e., polarized, glasses. One drawback of this technology is that without the glasses, it is impossible to visualize any content on the display and the device will not be useful at all. Further, users must always wear polarized glasses to see the screen content. This can be inconvenient for those who do not typically wear glasses or those who require glasses with prescription lenses. The polarizer glasses provide privacy by making the content visible only to the person wearing them. However, this exclusivity can be inconvenient in situations where multiple users need to view the display simultaneously, such as during a presentation or collaborative work session. This technology is designed specifically for LCD devices, which have a polarization layer. The technology might not work effectively with other types of display devices, such as Organic Light-Emitting Diode (OLED) based display devices. A privacy screen protector (PSP) is a thin plastic film, that can be applied directly to the screen. PSPs use a light-filtering technology called micro-louvers that limits the viewing angle of the screen, making the content visible only for the person directly in front of the screen. However, PSPs reduce the overall screen clarity and brightness, making it more difficult to view the content under certain lighting conditions. PSPs also restrict the viewing angles, which can be an inconvenience when a screen should be shared among a group of people or when working collaboratively. Installing a PSP can be tricky and may result in air bubbles, dust, or misalignment if not done correctly. This can affect the appearance and usability of the screen. PSPs can reduce the responsiveness of touch screen devices, making it harder to interact with the devices. Moreover, PSPs may not work well with certain device features, such as fingerprint scanners or facial recognition technology. PSPs can alter the appearance of the device, making it bulkier or less sleek.

[0011] Wearable displays such as Augmented Reality (AR) and Virtual Reality (VR) smart glasses (or other types of extended reality (XR) devices), allow wearer confidentially in that only the user wearing the smart glasses is enabled to view the content displayed by the smart glasses. Some smart glasses may still have technical limitations, such as limited field of view, low resolution displays, and latency issues, which can affect the overall user experience. Some smart glasses are provided as headsets which are bulky and heavy, causing discomfort. Users may experience fatigue, neck strain, or headaches from extended use of headsets. Headsets generally require a significant amount of processing power as well as generating a significant amount of heat. High-quality smart glasses can be expensive, which may limit their accessibility.

[0012] SUMMARY

[0013] An object of embodiments herein is to address the above issues.

[0014] A particular object is to provide an eyewear, a display device, and a privacy enhancement system where the screen brightness or placement of displayed objects does not need to change.

[0015] A particular object is to provide an eyewear, a display device, and a privacy enhancement system where public content can be viewed without any polarized glasses, smart glasses, headsets, or the like.

[0016] A particular object is to provide an eyewear, a display device, and a privacy enhancement system that do not require any PSP or similar technology.

[0017] A particular object is to provide an eyewear, a display device, and a privacy enhancement system where the field-of-view is not limited, as for smart glasses.

[0018] A particular object is to provide an eyewear, a display device, and a privacy enhancement system that do not require any headset, such as a head-mounted display (HMD), to be worn by the user.

[0019] A particular object is to provide an eyewear, a display device, and a privacy enhancement system where the eyewear requires less processing power than a headset. According to a first aspect the object is addressed by providing an eyewear for privacy enhancement. The eyewear comprises a support structure. The eyewear comprises at least one lens. The at least one lens is held by the support structure. The at least one lens comprises a transparent layer of metamaterial. The metamaterial comprises a structure in which incident light of a first infrared wavelength and incident light of a second infrared wavelength interfere to, through an optical process, produce outgoing light in a visible wavelength. The eyewear also comprises a power supply. The eyewear further comprises an infrared light source powered by the power supply, wherein the infrared light source is held by the support structure, and is tunable to emit light in the first or second infrared wavelength into the metamaterial.

[0020] According to a second aspect the object is addressed by providing a display device for privacy enhancement. The display device comprises a power supply for powering the display device. The display device comprises a screen for displaying content to a user. The screen comprises a first screen backlighting system configured to emit visible light for displaying a first part of the content. The screen comprises a second screen backlighting system configured to selectively illuminate at least one part of the screen with light in at least one infrared wavelength for displaying a second part of the content. Also, the second screen backlighting system is configured to simultaneously illuminate the at least one part of the screen with light in two infrared wavelengths.

[0021] According to a third aspect the object is addressed by providing a privacy enhancement system. The privacy enhancement system comprises a display device according to the second aspect. The privacy enhancement system comprises an eyewear according to the first aspect to be worn by a user when viewing content as displayed on a screen of the display device.

[0022] Compared to the aforementioned screen content protecting technologies, this eyewear, this display device, and this privacy enhancement system have an advantage in usability, lightweight design, cost etc.

[0023] Whilst smart glasses (and other types of XR devices) are bulky and heavy, the proposed eyewear can allow for lightweight design, yielding an eyewear that is comfortable to wear and easy to transport.

[0024] Advantageously, manufacturing of the proposed eyewear could be cheaper and simpler than for smart glasses.

[0025] Advantageously, the metamaterial can be integrated into various types of eyewear, such as prescription glasses and sunglasses.

[0026] Advantageously, the proposed eyewear needs only to be worn when private content is displayed on the display device. This is in contrast to the aforementioned polarized glasses and smart glasses which must always be worn for the user to see any content. Advantageously, the display device can be adapted so that private content is displayed on only a part of the screen. This is in contrast to the aforementioned polarized glasses and smart glasses, as well as PSPs, where either the whole screen or no part of the screen is visible to other users.

[0027] Advantageously, the proposed eyewear allows the user to view the displayed content in all viewing angles provided by the display, such as under normal vision. The proposed eyewear and display device thereby overcome issues with restricted viewing angles when using PSPs and issues with limited field-of-view when using smart glasses.

[0028] In some embodiments, the infrared light source is a collimated infrared light source, such as a Vertical Cavity Surface Emitting Laser (VCEL) diode.

[0029] In some embodiments, the infrared light source is tunable to emit light in different infrared wavelengths, and the eyewear further comprises a controller configured to control the infrared light source to temporarily change the infrared wavelength in which the infrared light source emits light.

[0030] In some embodiments, the infrared wavelength is temporarily changed according to a pattern as received by the controller from the display device.

[0031] In some embodiments, the eyewear further comprises a photodiode configured to detect a time sync signal emitted from the display device, and the controller is configured to control the infrared light source to temporarily change the infrared wavelength in accordance with the time sync signal.

[0032] In some embodiments, the at least one lens comprises at least two transparent layers of metamaterial, where each of the layers of metamaterial is tunable to produce outgoing light in a respective visible wavelength from incident light of a respective pair of infrared wavelengths.

[0033] In some embodiments, according to the structure, different areas of the metamaterial are configured to convert incident light in different pairs of infrared wavelengths to outgoing light of a respective visible wavelength.

[0034] In some embodiments, the at least one lens is applied to the at least one lens through nanofabrication.

[0035] In some embodiments, each of the at least one lens is disposed into two panes each, where the metamaterial is sandwiched between the two panes.

[0036] In some embodiments, the metamaterial is composed of GaAs nano antennas.

[0037] In some embodiments, the display device further comprises a switch, where the at least one part of the screen is illuminated with the infrared light only when the switch is activated. In some embodiments, the display device further comprises a controller configured to control the second screen backlighting system to temporarily change the at least one infrared wavelength.

[0038] In some embodiments, the at least one infrared wavelength is temporarily changed according to a pattern, and the controller further is configured to send the pattern towards the eyewear.

[0039] In some embodiments, the display device further comprises a visual indicator configured to visually emit a time sync signal towards the eyewear, and the controller is configured to control the second screen backlighting system to temporarily change the at least one infrared wavelength in accordance with the time sync signal.

[0040] In some embodiments, the controller further is configured to determine which at least one part of the screen is to be illuminated with the infrared light.

[0041] In some embodiments, the at least one part of the screen covers the entire screen.

[0042] In some embodiments, the at least one part of the screen covers less than the entire screen.

[0043] Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

[0044] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0045] BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

[0047] Fig. 1 is a schematic illustration of an eyewear for privacy enhancement according to embodiments;

[0048] Fig. 2 is a schematic illustration of a display device for privacy enhancement according to embodiments;

[0049] Figs. 3(a) and 3(b) are schematic illustrations of a privacy enhancement system according to embodiments;

[0050] Figs. 4(a) and 4(b) are schematic illustrations of content as displayed on a screen of a display device according to embodiments; and Fig. 5 is a schematic illustration of different combinations of infrared wavelengths according to an embodiment.

[0051] DETAILED DESCRIPTION

[0052] The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, 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 inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

[0053] In Fig. 1 is illustrated an eyewear 100 for privacy enhancement according to an embodiment. The eye wear 100 may be any type of glasses, ranging from smart glasses with built in electronics of various kinds to ordinary glasses with piano- or subscription lenses designed to correct for user vision problems, such as visual acuity, astigmatism, or the like. The eyewear 100 comprises a support structure 110. The support structure 110 could be a frame. The eyewear 100 comprises at least one lens 120a, 120b. The eyewear 100 could have an ordinary light-weight design with ordinary glass lenses.

[0054] The eyewear 100, and particularly the at least one lens 120a, 120b, comprises a metamaterial. In general terms, the metamaterial is tunable for the different wavelengths. In particular, the metamaterial comprises a structure in which incident light of a first infrared wavelength and incident light of a second infrared wavelength interfere to, through an optical process, produce outgoing light in a visible wavelength.

[0055] One non-limiting example of this is described in “Infrared upconversion imaging in nonlinear metasurfaces” by del Rocio et al in Advanced Photonics, Vol. 3, Issue 3, June 2021, as available per 6 December 2023 at https: / / doi.Org / 10.l 117 / 1.AP.3.3.036002. Accordingly, incident light of two different infrared wavelengths enters the metamaterial. The structure interacts with the two different wavelengths and creates a third, shorter wavelength, that if the structure is properly tuned, will be in the visible spectrum of the human vision system. Hence, the metamaterial will absorb incoming light of infrared wavelengths and, through a (nonlinear) optical process, emit light at a shorter wavelength in the range of the visible electromagnetic spectrum, i.e., 400 to 700 nm. Such a nonlinear optical process is sometimes referred to as sum-frequency generation (SFG) or second-harmonic generation (SHG). That is, in some examples, the optical process involves SFG or SHG. SFG typically occurs in metamaterial with a nonzero second-order nonlinear susceptibility, such as certain crystals and thin films.

[0056] In general terms, in SFG two photons of different frequencies (or wavelengths) interact with a nonlinear material (i.e., the metamaterial) and combine to generate a single photon of twice the frequency (or half the wavelength) of the original photons. Experiments in the aforementioned work “Infrared upconversion imaging in nonlinear metasurfaces” show that using incident light in two infrared wavelengths 1530nm and 860 nm, the SFG frequency-mixing process results in the generation of visible green light (with a wavelength of 550 nm), at which the human eye has maximum sensitivity.

[0057] Hence, the metamaterial, or at least its structure, needs to be selected appropriately, and the structure needs to be arranged in a way that exhibits the desired (nonlinear) optical properties. In this respect, there are different examples of metamaterials. In some embodiments, the metamaterial is composed of GaAs nano antennas. Such nano antennas have the ability to manipulate the wavelength of light that passes through them. Especially, nano antennas can convert light of infrared wavelengths to light of visible wavelengths.

[0058] There are different ways in which the at least one lens 120a, 120b is provided with the metamaterial. The metamaterial may be fabricated in different ways, for example using lithography or nanoimprint technology methods. In some embodiments, the metamaterial is applied to the at least one lens 120a, 120b through nanofabrication. The metamaterial can be provided as a transparent film-like layer that can be integrated into the at least one lens 120a, 120b. This integration may be done in such a way that the metamaterial remains transparent and minimally obstructive to the wearer's normal vision. In some aspects, the metamaterial is sandwiched between two layers of transparent material, such as glass or plastic, that forms the at least one lens 120a, 120b. Hence, in some embodiments, each of the at least one lens 120a, 120b is disposed into two panes each, and the metamaterial is sandwiched between the two panes.

[0059] In some aspects, several layers of metamaterial may be used with different tunable structures to yield different color output. Therefore, in some embodiments, the at least one lens 120a, 120b may comprise at least two transparent layers of metamaterial, where each of the layers of metamaterial is tunable to produce outgoing light in a respective visible wavelength from incident light of a respective pair of infrared wavelengths. In some aspects, one layer of metamaterial with different properties, may be used with different tunable structures to yield a different color output. Therefore, in some embodiments, according to the structure, different areas of the metamaterial may be configured to convert incident light in different pairs of infrared wavelengths to outgoing light of a respective visible wavelength. According to an example, three layers of metamaterial may be used with three different infrared activation wavelength pairs (this does not imply that there is need for six different wavelengths), and three different visible wavelengths are provided as output, giving the system the possibility to show full color output whilst still in a privacy mode.

[0060] As will be disclosed in further detail below, a screen backlighting system of a display device might be configured to selectively illuminate at least one part of a screen (which a user is to view whilst wearing the eyewear 100) with light in one or two (or more) infrared wavelengths. In this respect, in case the screen is illuminated with light in only one (first) infrared wavelength, the light of the second infrared wavelength need to be produced elsewhere. One example is for the light of the second infrared wavelength to be produced by a light source provided in the eyewear 100. Therefore, in some embodiments, the eyewear 100 is provided with at least one infrared light source 140a, 140b. The at least one infrared light source 140a, 140b is powered by a power supply 130. The infrared light source 140a, 140b is held by the support structure 110, and tunable to emit light in the first or second infrared wavelength into the metamaterial. There could be different examples of infrared light sources 140a, 140b. In some examples the at least one infrared light source 140a, 140b may be a collimated infrared light source, such as a VCEL diode.

[0061] As will be disclosed in further detail below, it could be so that the infrared wavelength of the light illuminating the screen varies over time. A consequence of this is that the infrared light source 140a, 140b needs to be tunable to emit light in different infrared wavelengths for the third wavelength (i.e., the wavelength in the visible spectrum of the human vision system) to be produced. In some embodiments, the eyewear 100 therefore further comprises a controller 150 configured to control the infrared light source 140a, 140b to temporarily change the infrared wavelength in which the infrared light source 140a, 140b emits light. In some embodiments, the infrared wavelength is temporarily changed according to a pattern as received by the controller 150 from the display device. The pattern may be changed according to some time sync with the display device. In some aspects, the eyewear 100 therefore may comprise some type of receiver for receiving a time sync signal from the display device. The receiver may be a radio receiver or another type of receiver. In some examples, the receiver may be a photodiode 160. Therefore, in some embodiments, the eyewear 100 may further comprise a photodiode 160 configured to detect a time sync signal emitted from the display device. The controller 150 is then configured to control the infrared light source 140a, 140b to temporarily change the infrared wavelength in accordance with the time sync signal.

[0062] Reference is next made to Fig. 2 which schematically illustrates a display device 200 for privacy enhancement according to an embodiment. The display device may be a monitor, television set, handset, tablet computer, laptop computer, etc. The display device 200 comprises a power supply 260 for powering the display device 200. The display device 200 further comprises a screen 210 for displaying content to a user. In turn, the screen 210 comprises a first screen backlighting system 220 configured to emit visible light for displaying a first part of the content. The first screen backlighting system 220 may be an LCD panel or OLED panel as used in existing flat panel displays, such as monitors, television sets, handsets, tablet computers, laptop computers, etc. The display device 200 is further configured to emit light of at least one infrared wavelength. The screen 210 therefore further comprises a second screen backlighting system 230 configured to selectively illuminate at least one part of the screen 210 with light in at least one infrared wavelength for displaying a second part of the content. For this purpose the second screen backlighting system 230 may comprise infrared light diodes. In some examples, the second screen backlighting system 230 may be integrated with the first screen backlighting system 220 and comprise subpixels emitting the light of the infrared wavelength. The display device 200 may further comprise a controller 240 (with integrated or separate memory) configured to run applications, to control the displaying of content on the screen 210, to decide what content is private or public, to control the at least one infrared wavelength of the second screen backlighting system 230, etc.

[0063] As disclosed above, the metamaterial needs incident light of two infrared wavelengths to produce outgoing light of a visible wavelength. For this purpose, in some embodiments, the second screen backlighting system 230 may be configured to simultaneously illuminate the at least one part of the screen 210 with light in two infrared wavelengths. The alternative has been disclosed above, namely that light of the second infrared wavelength is produced elsewhere, such as by an infrared light source 140a, 140b in the eyewear 100.

[0064] In some aspects, the privacy enhancement is selectably enabled and disabled. The display device 200 might further comprise a switch 270 for this purpose. The switch 270 could be a mechanical switch, an electronic switch, a micro-electromechanical switch, or be implemented in software. The at least one part of the screen 210 is then illuminated with the infrared light only when the switch 270 is activated. In this way, when the user of the display device 200 needs to review some sensitive content on the screen 210 in a privacy mode, they only need to activate the switch 270 and put on the eyewear 100. The whole screen 210 or some of its parts is then illuminated with light in an infrared wavelength, causing the content to be visible to the wearer of the eyewear 100 whilst staying invisible to others.

[0065] In some aspects, the at least one infrared wavelength is temporarily changed. Therefore, in some embodiments, the controller 240 may be configured to control the second screen backlighting system 230 to temporarily change the at least one infrared wavelength. In this respect, in case the second screen backlighting system 230 is configured to illuminate the at least one part of the screen 210 with light in only one infrared wavelength at a time, information about the pattern needs to be communicated to the infrared light source 140a, 140b in the eyewear 200. That is, in some embodiments, the at least one infrared wavelength may be temporarily changed according to a pattern, and the controller 240 may be configured to send the pattern towards the eyewear 100. In this respect, the pattern may be random, selected from a look-up table, etc.

[0066] Further, as disclosed above, the pattern may be changed according to some time sync. In some aspects, the display device 200 therefore comprises some type of transmitter for transmitting a time sync signal towards the eyewear 100. The transmitter may be a radio transmitter or another type of transmitter. In some examples the transmitter may be a visual indicator 250. In some embodiments, the visual indicator 250 may be configured to visually emit a time sync signal towards the eyewear 100, and the controller 240 may be configured to control the second screen backlighting system 230 to temporarily change the at least one infrared wavelength in accordance with the time sync signal. As disclosed above at least one part of the screen 210 is to be illuminated with the infrared light. In this respect, the controller 240 might further be configured to determine which at least one part of the screen 210 is to be illuminated with the infrared light. The decision regarding which at least one part of the screen 210 is to be illuminated with the infrared light may depend on the content that is to be disclosed on the screen 210. In some embodiments, the at least one part of the screen may cover the entire screen 210. In other embodiments, the at least one part of the screen may cover less than the entire screen 210. Further aspects of this will be disclosed below with reference to Fig. 4.

[0067] A privacy enhancement system comprises a display device 200 as herein disclosed and an eyewear 100 as herein disclosed to be worn by a user when the user is viewing content as displayed on the screen 210 of the display device 200. Such a privacy enhancement system is schematically illustrated in Fig. 3(a) and Fig. 3(b), where the eyewear 100 is represented by the at least one lens 120a, 120b. In more detail, in Fig. 3(a) and Fig. 3(b) are illustrated two different embodiments of the privacy enhancement system.

[0068] In Fig. 3(a) an embodiment is illustrated where light 320a, 320b of two different infrared wavelengths is illuminating the screen of the display device 200. The light of one or both of the infrared wavelengths then carries the content that is to be privacy protected. The light 320a, 320b in the two different infrared wavelengths is received as incident light at the metamaterial 310 of the at least one lens 120a, 120b to produce outgoing light 330 of a wavelength that is visible to the user 340. In this embodiment, the eyewear 100 may be created as a zero-energy device because its full functionality does not require any integrated electronics and thus does not need to be powered. The display device 200 needs to supply (at least) two infrared wavelengths. These (at least) two infrared wavelengths may be different from one display device 200 to another to yield extra security between different display devices 200. In some aspects, the eyewear 100 is provided with a code or other type of marking so that the display device 200 can be setup to use light 320a, 320b of two different infrared wavelengths that through an optical process in the metamaterial 310 produce outgoing light 330 of a visible wavelength. For this purpose, the display device 200 may be configured to scan the marking, or the user may enter the code through a user interface of the display device 200, so that the display device 200 can be properly setup. The display device 200 may then, in accordance with the information provided by the marking, select any pair of infrared wavelengths (possibly changing over time) that through the optical process in the metamaterial 310 produces outgoing light 330 in a visible wavelength.

[0069] In Fig. 3(b) is illustrated an embodiment where light 320a of one (first) infrared wavelength is illuminating the screen of the display device 200 and where light 320b of one (second) infrared wavelength is produced by the infrared light source 140a, 140b. The light 320a of the infrared wavelength illuminating the screen of the display device 200 then carries the content that is to be privacy protected. Having the eyewear 100 and the display device 200 separated in this way increases the security as only one special eyewear 100 with a specific wavelength and a specific structure in the metamaterial will be able to view the secure content. This also simplifies the design of the display device 200, since only one of the two infrared wavelengths per visual wavelength needs to be supported by the second screen backlighting system 230. In some aspects, both the display device 200 and the eyewear 100 (by means of the infrared light source 140a, 140b) have the possibility to change the infrared wavelength. Accordingly, the display device 200 may select a pattern according to which the infrared wavelength of the light 320a is changed over time and transfer this pattern to the eyewear 100. The controller 150 in the eyewear 100 will then control the infrared light source 140a, 140b to temporarily change the infrared wavelength in which the infrared light source 140a, 140b emits light 320b in accordance with the pattern and according to a time sync signal emitted by the display device 200.

[0070] Reference is next made to Fig. 4(a) and Fig. 4(b), schematically illustrating content 400a, 400b as displayed on the screen 210 of the display device 200. In Fig. 4(a) the content 400a is visible to all users. In Fig. 4(b) the content 400b is visible to users wearing the eyewear 100 (matched to the display device 200). The content 400a includes a first visual object 410a and a first text field 420a. The first visual object 410a and the first text field 420a may for this purpose be tagged as public and are thus shown to all users. The first visual object 410a and the first text field 420a are displayed by means of the first screen backlighting system 220. The content 400b includes the content 400a as well as a second visual object 410b and a second text field 420b. The second visual object 410b and the second text field 420b may for this purpose be tagged as private and are thus shown only to users wearing the eyewear 100. The second visual object 410b and the second text field 420b are displayed by means of the second screen backlighting system 230. One example of this is that a user may have a teleprompter in private mode showing text (such as the second text field 420b) in the presentation while presenting. There could also be information in the presentation (such as the second visual object 410b and / or the second text field 420b) that is security classified and then only users wearing the eyewear 100 will see that information. The same presentation could then be presented to two different audiences at the same time, providing more information to the audience with the required security clearance.

[0071] As an example, laser diodes generally have a very short bandwidth. This may be utilized to increase the security. For example, as disclosed above, the infrared wavelength may be temporarily changed so that it becomes harder for an eavesdropper to intercept any private content. Here, both the first infrared wavelength and the second wavelength may be changed temporarily according to some agreed pattern and time sync. There should be at least two pairs of infrared wavelengths i.e., where each such pair consist of one first infrared wavelength and one second infrared wavelength. In Fig. 5 an example is shown where there are three such pairs of infrared wavelengths, and where the infrared wavelengths change over time (at occasions tO, tl, and t2). The time interval according to which the wavelengths change (i.e., the difference between tl and tO, etc.) may, for example, be in the range from milliseconds to seconds. As examples, the wavelength may be changed every time there is a content change or according to some event (e.g., provided as a time stamp in the content to be displayed) or at random points in time. For illustrative purposes, “Source” represents the infrared wavelength of the light emitted by the second screen backlighting system 230 in the display device 200, “Feed A” represents the infrared wavelength of the light emitted by the infrared light source 140a, 140b in a first eyewear 100 matched (in terms of pattern and time sync) to the display device 200, and “Feed B” represents the infrared wavelength of the light emitted by the infrared light source in a second eyewear not matched to the display device 200. Rather, the infrared wavelength of “Feed B” is static over time.

[0072] At time tO, Source and Feed A are set to the first possible combination of infrared wavelength. Since Feed B is not matched to the infrared wavelength of the Source, a user wearing the second eyewear is not able to see the content.

[0073] At time tl, Source and Feed A are set to a second possible combination of infrared wavelength. Since Feed B is not matched to the infrared wavelength of the Source, a user wearing the second eyewear is not able to see the content.

[0074] At time t2, Source and Feed A are set to the third possible combination of infrared wavelength. The static infrared wavelength of Feed B matches the infrared wavelength of the Source. Therefore, a user wearing the second eyewear is able to see the content (but at lower intensity). The latter is the case since the feeds at times tO, tl and t2 can be combined if the switching time is fast enough. Otherwise, the eavesdropper will not see content at times tO and tl but only at time t2.

[0075] In case the infrared light source in the second eyewear is tunable, then it may be possible to adapt the infrared wavelength of the infrared light source in the second eyewear over time in an effort to find the pattern used by the Source. However, since there may be many infrared wavelengths to select from and since the changes from one combination of infrared wavelengths could be periodic (with high frequency of change, content dependent, or even random, it is envisioned that it will be difficult to match the second eyewear to the display device 200 with reasonable effort.

[0076] The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

CLAIMS1. An eyewear (100) for privacy enhancement, the eyewear (100) comprising: a support structure (110); and at least one lens (120a, 120b), the at least one lens (120a, 120b) being held by the support structure (110) and comprising a transparent layer of metamaterial (310), wherein the metamaterial (310) comprises a structure in which incident light (320a) of a first infrared wavelength and incident light (320b) of a second infrared wavelength interfere to, through an optical process, produce outgoing light (330) in a visible wavelength, a power supply (130); characterized in that the eyewear (100) further comprises an infrared light source (140a, 140b) powered by the power supply (130), wherein the infrared light source is held by the support structure (110), and is tunable to emit light (320a, 320b) in the first or second infrared wavelength into the metamaterial (310).

2. The eyewear (100) according to claim 1, wherein the infrared light source (140a, 140b) is a collimated infrared light source, such as a Vertical Cavity Surface Emitting Laser, VCEL, diode.

3. The eyewear (100) according to claim 1 or 2, wherein the infrared light source (140a, 140b) is tunable to emit light (320a, 320b) in different infrared wavelengths, and wherein the eyewear (100) further comprises: a controller (150) configured to control the infrared light source (140a, 140b) to temporarily change the infrared wavelength in which the infrared light source (140a, 140b) emits light (320a, 320b).

4. The eyewear (100) according to claim 3, wherein the infrared wavelength is temporarily changed according to a pattern as received by the controller (150) from a display device (200).

5. The eyewear (100) according to claim 4, wherein the eyewear (100) further comprises: a photodiode (160) configured to detect a time sync signal emitted from the display device (200), and wherein the controller (150) is configured to control the infrared light source (140a, 140b) to temporarily change the infrared wavelength in accordance with the time sync signal.

6. The eyewear (100) according to any preceding claim, wherein the at least one lens (120a, 120b) comprises at least two transparent layers of metamaterial (310), and wherein each of the layers of metamaterial (310) is tunable to produce outgoing light (330) in a respective visible wavelength from incident light (320a, 320b) of a respective pair of infrared wavelengths.

7. The eyewear (100) according to any of claims 1 to 6, wherein according to the structure, different areas of the metamaterial (310) are configured to convert incident light (320a, 320b) in different pairs of infrared wavelengths to outgoing light (330) of a respective visible wavelength.

8. The eyewear (100) according to any preceding claim, wherein the metamaterial is applied to the at least one lens (120a, 120b) through nanofabrication.

9. The eyewear (100) according to any of claims 1 to 7, wherein each of the at least one lens (120a, 120b) is disposed into two panes each, and wherein the metamaterial (310) is sandwiched between the two panes.

10. The eyewear (100) according to any preceding claim, wherein the metamaterial (310) is composed of GaAs nano antennas.

11. A display device (200) for privacy enhancement, the display device (200) comprising: a power supply (260) for powering the display device (200); and a screen (210) for displaying content to a user (340), the screen (210) comprising: a first screen backlighting system (220) configured to emit visible light (330) for displaying a first part of the content; and a second screen backlighting system (230) configured to selectively illuminate at least one part of the screen (210) with light (320a, 320b) in at least one infrared wavelength for displaying a second part of the content, characterized in that the second screen backlighting system (230) is configured to simultaneously illuminate the at least one part of the screen (210) with light (320a, 320b) in two infrared wavelengths..

12. The display device (200) according to claim 11, further comprising a switch (270), wherein the at least one part of the screen (210) is illuminated with the infrared light (320a, 320b) only when the switch (270) is activated.

13. The display device (200) according to claim 11 or 12, wherein the display device (200) further comprises: a controller (240) configured to control the second screen backlighting system (230) to temporarily change the at least one infrared wavelength.

14. The display device (200) according to claim 13, wherein the at least one infrared wavelength is temporarily changed according to a pattern, and wherein the controller (240) further is configured to send the pattern towards an eyewear (100).

15. The display device (200) according to claim 14, wherein the display device (200) further comprises: a visual indicator (250) configured to visually emit a time sync signal towards the eyewear (100), and wherein the controller (240) is configured to control the second screen backlighting system (230) to temporarily change the at least one infrared wavelength in accordance with the time sync signal.

16. The display device (200) according to claim 13 to 15, wherein the controller (240) further is configured to determine which at least one part of the screen (210) is to be illuminated with the infrared light (320a, 320b).

17. The display device (200) according to any of claims 11 to 16, wherein the at least one part of the screen covers the entire screen (210).

18. The display device (200) according to any of claims 11 to 16, wherein the at least one part of the screen covers less than the entire screen (210).

19. A privacy enhancement system comprising: a display device (200) according to any of claims 1 to 18 and an eyewear (100) according to any of claims 1 to 20 to be worn by a user (340) when viewing content as displayed on a screen (210) of the display device (200).

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