FIELD OF THE INVENTION

The present invention relates to a head-mountable computing device comprising at least one display module and a processor for controlling the at least one display module to display motion information on the display module.

The present invention further relates to a use of the head-mountable computing device for adjusting a circadian rhythm of a wearer.

The present invention further relates to a method for displaying motion information on a head-mountable computing device.

The present invention further relates to a computer program product for implementing such a method when executed on a processor of such head-mountable computing device.

BACKGROUND OF THE INVENTION

Head-mountable computing device, a wearable near-to-eye display device worn on the head of a wearer, has been used in research, military and gaming industry. Such head-mountable computing device can generate video and/or audio information to the user in order to alleviate the uncomfortableness of the user, such as occurs with stress, motion sickness, etc.

US8692845 B2 discloses a head-mounted display including one or more independently controllable switchable viewing areas that are each independently switched between a transparent viewing state, a partially transparent state, and an information viewing state, a processor for analyzing the image sequence information to produce a signal estimating the propensity of the image sequence information to induce motion sickness or symptoms of motion sickness in the user, and modifying the state of each of the one or more independently switchable viewing areas to reduce the propensity of the image sequence information to induce motion sickness or symptoms of motion sickness in the user. SUMMARY OF THE INVENTION

It is an object of the present invention to provide a head-mountable computing device for displaying motion illusion stimuli.

It is further an object of the present invention to provide a method for displaying motion illusion stimuli using such a head-mountable module.

It is further an object of the present invention to provide a computer program product for implementing such a method when executed on a processor of such head- mountable computing device.

According to an aspect, there is provided a head-mountable computing device comprising:

at least one display module;

at least two sensors, the at least two sensors comprising a first type of sensor for measuring data indicative of the phase of the current circadian rhythm of the wearer, and a second type of sensor for measuring data indicative of the phase of the current solar cycle; and

a processor adapted to:

- initialize the at least one display module;

- receive the measured data indicative of the phase of the current circadian rhythm of the wearer from the first type of sensor and the measured data indicative of the current solar cycle from the second type of sensor;

- determine the phase of the current circadian rhythm of the wearer and the phase of the current solar cycle from the received data;

- compare the phase of the current circadian rhythm of the wearer with the phase of the current solar cycle;

- control the at least one display module to display motion information to a wearer of the head-mountable computing device by displaying moving elements representing a motion scene to the wearer; and

- adjust the displayed motion information based on the comparison result of the phase of the current circadian rhythm of the wearer and the phase of the current solar cycle.

The motion information provided by the head-mountable computing device may in the following also be referred to as motion illusion information.

A circadian rhythm relates to any biological process that displays an endogenous, entrainable oscillation of about 24 hours. These 24 hour rhythms are driven by a circadian clock or pacemaker. The pacemaker is sometimes out of synchronization with the solar time e.g. due to travelling jetlag) and shift work. Health problems can result from a disturbance to the circadian rhythm, such as metabolic disorders like obesity and diabetes, or sleep problems with associated consequences such as fatigue and even depression. Exposure to shifted light dark rhythms can even cause (increased probability of recurrence of) psychiatric problems, evoke a continuous feeling of strange misbelonging, as if something is out of the ordinary, increase the risk of being affected by psychiatric mood disorders, and/or significant shrinkage of the volume of the brain's temporal lobe (which is involved in the processing of sensory input, memory, emotion, and comprehension). The aim of the current invention is to avoid, and if they occur, to overcome these problems.

Normally, daily rhythms of the brain's internal central pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) stay synchronized with time-specifying signals (such as the light-dark cycle). The brain's internal central pacemaker includes a light- responsive part, namely the ventral part, that is connected to the eye and a light-unresponsive part, namely the dorsal part. The dorsal part governs the timing of all processes in the body (such as cell division), and the ventral part is synchornized to the solar rhythm. Adjustment of the brain's pacemaker to a shifted light-dark cycle (such as needed with jetlag, shift work, and surgery) depends on the neurochemical communication between the ventral and the dorsal parts. Input into the pacemaker in the form of neurotransmitters and hormones can potentiate the phase-shifting effects of light.

The current state of the art solutions for adjusting rhythms are mainly pharmacological, focusing on alleviation of mentioned effects. Pharmacological approaches do not facilitate the communication between the light-responsive part and the light- unresponsive part of the brain's pacemaker.

The present invention is based on the insight that the generation of an illusion of locomotion to a wearer of the a head-mountable computing device may induce the brain of the user to generate neurochemical substances that, in turn, facilitate the adjustment of the temporal phase of the brain's central pacemaker to a shifted light-dark cycle.

Locomotion-related signals facilitate the synchronization of the dorsal part to the ventral part through levels of the hormone vasopressin. Vasopressin plays a key role in robustness of the dorsal part of the pacemaker and confers on the brain's internal central pacemaker an intrinsic resistance to external light-dark perturbation. Physical exercise, or locomotion in general, influences vasopressin reciprocally, namely the dorsal part becomes more sensitive to the ventral part during locomotion. These results indicate that corticosterone in the blood/body-cells may regulate the circadian rhythm through vasopressin variation in the brain's internal central (single) pacemaker.

By displaying motion illusion stimuli, hereinafter also refer to motion illusion information, via the display module of the head-mountable computing device to the wearer, the locomotion illusion induced by the virtual reality stimulus may cause the wearer's cardiovascular responses that are similar to cardiovascular responses to real locomotion, for instance, a significant increase in heart rate, heart rate variability, mean arterial

bloodpressure, respiration, and skin conductance. It is understood that the current invention can be used in many circumstances or conditions, such as jetlag, shift work and surgery.

The motion illusion information displayed on the display module may be updated based on the current solar cycle and the current circadian rhythm of the wearer. The head-mountable computing device may comprise one or more sensors for measuring and recognizing the phase of the current cirdadian rhythm of the wearer. The processor of the head-mountable computing device may be further configured for adjusting the displayed motion illusions information based on the comparison result of the phase of the current circadian rhythm of the wearer and the phase of the current solar cycle. Normally, the core body temperature values collected over a period of at least 24 hours may reflect the phase of the current circadian phase of the SCN's biological clock. Therefore, the core body temperature values can be used as the input of processor. In other words, the wearer's circadian phase derived from the core body temperature values may enable the estimation of the difference between the phase of the SCN's biological clock and desired (solar) clock, namely the current solar cycle. For instance, the phase onset of the body temperature may be fed back to the processor that compares this onset with the onset of the phase of the solar cycle. If there is a discrepancy between these two values, the wearer may be informed that his/her biological clock is not in phase with the solar cycle. Accordingly, the motion illusion information displayed on the display module may be automatically adjusted.

In an embodiment, the duration of the motion illusion information may be automatically extended or shortened depending on the discrepancy between the current solar cycle and the current circadian rhythm of the wearer. Alternatively, the content of the motion illusion information may be automatically updated. For instance, the motion illusion information may be changed from a relatively slow moving illusion scene, e.g. snow storm with slow moving elements, to a scene with fast moving elements, e.g. heavy snow storm. Alternatively, the head-mountable computing device may comprise a user interace to allow the wearer to manually select a desired duration as well as desired content of the motion illusion information.

In an embodiment, the display module may be an array of LEDs located on a frame of the head-mountable computing device, in particular a linear array, e.g. Knight Rider© LED Scanner, or an array where one LED is on for a short moment, and it dimmed then while its neighbour LED is switched on.

In an embodiment, the display module may be a 2D display module, e.g. Google Glass© screen, that a wearer of the head-mountable computing device can observe an image or data displayed on the at least one display module, which may provide similar effect as the array as mentioned above, but more advanced schemes and colors can be

accomplished.

In an embodiment, the display module may be a 3D display module for displaying images and/or videos with 3D effect, which may demonstrate stronger movement effects than the abovementioned 2D display module, e.g. displaying a movement of trains with 3D effect.

It is understood by the person skilled in the art that the display module for displaying virtual reality stimulus information containing motion illusion information can be implemented in various fashions other than above-mentioned examples.

In an embodiment, the processor of the head-mountable computing device is further adapted for controlling the array of LEDs to generate a vection motion illusion information. For instance, when a person sits in an unmoving train while looking at an adjacent (on a neighbor track) train that starts moving. This often gives us the illusion that we move ourselves. This illusion can be created by a set of adjacent LEDs that turn on. A particular embodiment of display module for displaying the vection motion illusion information is an array of LEDs, preferably white or blue LEDs where the LEDs are not active all in parallel, but in a fashion which suggests vection, e.g. only one LED is turned on at one moment for a short period of time and dimmed afterward, and meanwhile the neigbouring LED starts and so on. It is understood that many variations of the vection motion illusion information as well as the corresponding display modules are possible.

In an embodiment, the processor of the head-mountable computing device is further adapted for controlling the array of LEDs to generate a "tunnel" motion illusion information. For instance, turning on the neighboring LEDs just after one another could mimick moving dots such that an illusion can be created to the wearer as if the wearer is moving in a tunnel with side lights. It is understood that many variations of the tunnel motion illusion information as well as the corresponding display modules are possible.

In an embodiment, the display module is configured for generating a 2D array of dots, wherein the processor is further adapted for controlling the movement of the 2D array of dots in order to generate an optic flow motion illusion scene. For instance, the 2D array of dots may be controlled to move in such a way as if the observer is moving through a snow storm. In an embodiment, the 2D array of dots may be controlled to move in such a way that the optic flow can be created, and an illusion can be created to the wearer as if the wearer is moving through a cloud of dots. It is understood that many variations of the optic flow motion illusion information as well as the corresponding display modules are possible.

In an embodiment, the motion illusion information may be supported by additional medium stimulation, e.g. multisensory stimulation. In an embodiment, the mountable computing device may comprise a Transcutaneous Electrical Nerve Stimulation (TENS) subsystem as additional medium stimualtion. An example of such stimulation is to use an array of TENS electrodes comprising TENS electrodes adjacent to each other which are one at the time after each activated. In an embodiment, the head-mountable computing device may comprise an amplifier to provide audio signals to the wearer in order to enhance the motion illusion information. For instance, additional sounds may be added during the displaying of the train departure illusion informaiotn in order to enhance vection motion illusion.

It is understood by the person skilled in the art that the motion illusion information displayed on the display module can be implemented in various manners other than the above-mentioned examples. Such motion illusion information may be preprogrammed and predefined. Alternatively, preferred motion illusion information may be choosen by the individual user.

In an embodiment, the head-mountable computing device may comprise one or more sensors for measuring the core body temperature (CBT) of the wearer. Core body temperature is regarded as an accurate reflection of the activity of the pacemaker in the SCN. Ideally, the sensors as well as a memory or a data storage for storing the measured core body temperature data may be located in the head-mountable computing device. Measurements could be done through a temperature sensor (with IR-light, or another temperature measurement device) located in the head-mountable computing device close to the ear of the wearer, or using an in-ear temperature sensor, or using surrogate temperature measurements sensor for sensing rectal and oesophagus temperatures, etc.. In another embodiment, core body temperature is obtained from a multitude of skin temperature sensors position on different parts of the body, preferably at distal locations. In another embodiment,

measurements of physical activity may be used to determined circadian phase. Such physical activity may be running, walking, or sleeping, and may be measured by physical activity sensor, such as an forward-facing image/video sensor, or a motion sensor such as a gyoscope and/or an acccelerometer located in the head-mountable computing device.

In an embodiment, the head-mountable computing device may comprise one or more sensors for measuring heart rate. Heart rate variability has become a common measurement of cardiovascular regulation by the autonomic nervous system. Using heart rate intervals, together with data from physical activity sensors, it is possible to predict human circadian phase based on, as few as, only 24 hours of data. These data can easily be recorded in ambulatory conditions. The heart rate intervals can be obtained with several embodiments, e.g. via ECG measurements using electrodes on the body or with photoplethysmography (PPG) sensors located in the head-mountable computing device, or in a separate component of an external system, such as a wrist-worn device, or an in-ear device.

In an embodiment, the head-mountable computing device may comprise a subprocessor configured for excuting a mathematical models of the human Circadian pacemaker in order to determine the current circadian phase. These mathematical models take ambient light levels and sleep-wake timing data as inputs and produce an estimate of the phase and amplitude of the circadian system. The ambient light levels may be measured by a ambient light sensor. The ambient light sensor may measure the ambient light levels the wearer is exposed to at the time of the stimulation, namely commencing the displaying of the motion illusion information. These light levels can easily differ from the natural light conditions due to the vast amount of electric light sources found almost everywhere nowadays. If the ambient light conditions are not favorable, e.g. too low or too bright, for the desired circadian phase shift at the moment when the visual stimulation should start, the visual stimulation can be delayed until the light levels match the desired input to the circadian system. The sleep-wake timing data may be measured by an physical activity sensor, such as an acccelerometer. In an embodiment, these models additionally take the timing of the visual stimulation into account to correct for the increased circadian stimulation at the time of the stimulus application. To measure the sleep-wake timing needed as input, the system can make use of a physical activity sensor from which sleep-wake patterns can be derived using well-known methods such as comparing activity levels against thresholds to classify time epochs into either sleep or wake. The physical activity sensor and the ambient light sensor may be integrated into the head-mountable computing device or can alternatively be integrated into a separate component of an external system such as a wrist-worn device.

The head-mountable computing device may comprise one or more sensors for measuring and recognizing the phase of the current solar cycle.

In an embodiment, the head-mountable computing device may comprise a light sensor configured for determining the phase of the current solar cycle. The light sensor may be configured for measuring the variation of the ambient light intensity and is therefore capable to determine the episodes of dawn and dusk.

In an embodiment, the processor is further adapted for automatically initializing the display module and controlling to display the motion illusion information by taking into account the data received from the light sensor. This is because the motion illusion information may be provided only when the current circadian rhythm needs to be shifted and the current light levels are consistent with the required light levels. This is to prevent that the motion illusion information is amplifying an non-desired circadian shift, for example, in the late evening when the wearer is exposed to bright levels of artificial light. In this case, the motion illusion information may be automatically provided to the wearer only when the ambient light levels are dimmed which is the required light levels. Similarly, in the morning, the motion illusion information may be provided to the wearer only if the ambient light levels are bright.

In addition, research shows that the generation of glucocorticoids will be effective in adjusting the brain's pacemaker during episodes of dawn and dusk in the timeframe of the observer's biological clock. In a preferred embodiment, the motion illusion information may be automatically provided to the wearer controlled by the processor only if:

there is a discrepancy between the current solar cycle and the current circadian rhythm of the wearer, wherein the current solar cycle may be measured by the light sensor;

the current light levels are consistent with the required light levels, wherein the required light levels may be measured by the light sensor; and

the current solar cycle is dawn or dusk, wherein the current solar cycle may be measured by the light sensor.

In an embodiment, the head-mountable computing device may comprise a satellite positioning systems, such as GPS or GLONASS, for deriving the current geo- position of the wearer and the time-of-year information so as to determine the phase of the current solar cycle of the wearer. It is understood that the current geo-position information and the time-of-year information may be obtained using data derived from other positioning systems located in an external device.

In an embodiment, the head-mountable computing device may comprise an optical filter configured for varying the gray level of the display module in order to remove excess light stimulus when the display module is displaying motion illusion scene.

In an embodiment, the head-mountable computing device may comprise a light source which may emit an additional light stimulus to the circadian system when the display module is displaying motion illusion scene.

In an embodiment, the sensors for measuring the geo-position, time-of-year, activity and ambient light may be located in a portable electronic devices such as the mobile phone (or tablet or smart watch) of the wearer. For this purpose, the head-mountable computing device may have a wireless communication interface (e.g. Bluetooth) for wirelessly communicating with a further remote system, such as a mobile phone, tablet or smart watch, to retrieve the needed sensor data. In an embodiment, the wireless

communication interface is also configured for wirelessly communicating with a further remote system, e.g. a wireless LAN, through which the head-mountable computing device may access a remote data source such as the Internet, for instance to store data such as user preferences, user specific information, and so on.

According to another aspect, there is provided a use of the head-mountable computing device according to one or more of the above embodiments for adjusting a cardiac rhythm of a wearer of the head-mountable computing device.

According to another aspect, there is provided a method of displaying information on the head-mountable computing device according to one or more of the above embodiments, the method comprising:

- initializing the at least one display module;

receiving data indicative of the phase of the current circadian rhythm of the wearer and data indicative of the current solar cycle;

deriving the phase of the current circadian rhythm of the wearer and the phase of the current circadian rhythm of the wearer based on the received corresponding data; - comparing the phase of the current circadian rhythm of the wearer with the phase of the current solar cycle;

controling the at least one display module to display motion information to a wearer of the head-mountable computing device by displaying moving elements representing a motion scene to the wearer; and adjusting the displayed motion information based on the comparison result of the phase of the current circadian rhythm of the wearer and the phase of the current solar cycle.

In accordance with yet another aspect, there is provided a computer program product comprising a computer program code for, when executed on the processor of the head-mountable computing device according to one or more of the above embodiments, implementing the steps of the method according to one or more of the above embodiments. Such a computer program product may be made available to the head-mountable computing device in any suitable form, e.g. as a software application (app) available in an app store, and may be used to configure the head-mountable computing device such that the head- mountable computing device may implement the aforementioned method.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described in more detail and by way of non- limiting examples with reference to the accompanying drawings, wherein

Fig. 1 schematically depicts a head mountable computing device according to an embodiment of the present invention;

Fig. 2 schematically depicts an aspect of the head mountable computing device of Fig. 1 according to an embodiment of the present invention;

Figs. 3a-3d schematically depict some embodiments of the head mountable computing device of Fig. 1;

Figs. 4a-4b show flow charts of methods according to an embodiment of the present invention;

Fig. 5 shows an example of the head mountable computing device of Fig. 1 according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

In the context of the present application, a head-mountable computing device is a device that can be worn on the head of its user and provides the user with computing functionality. The head-mountable computing device may be configured to perform specific computing tasks as specified in a software application (app) that may be retrieved from the Internet or another computer-readable medium. Non-limiting examples of such head- mountable computing devices include smart headgear, e.g. eyeglasses, goggles, a helmet, a hat, a visor, a headband, a Google Glass, or any other device that can be supported on or from the wearer's head, and so on.

In the context of the present application, the head-mountable computing device may comprise at least one first type of sensor for measuring data indicative of the phase of the current circadian rhythm of the wearer. The first type of sensors may comprise a physical activity sensor; and/or a temperature sensor for measuring the current temperature of the wearer; a sensor for measuring the heartbeat of the wearer. The sensor for measuring the heartbeat may be an ECG sensor, and/or a PPG sensor. The PPG sensor may be a mounted device, or built into another device, e.g. a wrist worn device and communicates the measured data with the head mountable device. The physical activity sensor may be a forward-facing image sensor, a gyoscope, and/or an acccelerometer. By analyzing the sensed data derived from the first type of sensor, the phase of the current circadian rhythm of the wearer can be determined. Such first type of sensor may be integral to the head-mountable computing device. Alternatively, the first type of sensor may be intergral to an external device, such as a smartphone, a tablet, etc., or other head-mountable computing device, and is

communicatively coupled via a wired or wireless connection to the head-mountable computing device. Alternatively, the data derived from the the first type of sensor may be directly derived from a remote data source such as the Internet/Cloud.

In the context of the present application, the head-mountable computing device may comprise at least one second type of sensor for measuring data indicative of the phase of the current solar cycle. The second type of sensors may comprise a light sensor and/or a satellite positioning system. By analyzing the sensed data derived from the second type of sensor, the phase of the current solar cycle can be determined. Such second type of sensor may be integral to the head-mountable computing device. Alternatively, the second type of sensor may be intergral to an external device, such as a smartphone, a tablet, a wrist worn device, etc., or other head-mountable computing device, and is communicatively coupled via a wired or wireless connection to the head-mountable computing device.

Alternatively, the data derived from the the second type of sensor may be directly derived from a remote data source such as the Internet/Cloud.

Figure 1 schematically depicts an embodiment of a head-mountable computing device 100. Figure 2 schematically depicts a block diagram of an embodiment of the head- mountable computing device 100, further highlighting the functionality of the head- mountable computing device 100 in terms of functional blocks, at least some of which may be optional functionality. By way of non-limiting example, the head mountable computing device 100 is depicted as smart glasses, but it should be understood that the head-mountable computing device 100 may take any suitable shape as previously explained.

The head-mountable computing device 100 comprises a first type of sensor

142 for measuring data indicative of the phase of the current circadian rhythm of the wearer of the head-mountable computing device 100 and a second type of sensor 144 for measuring data indicative of the phase of the current solar cycle. Any suitable first type of sensor 142 and second type of sensor 144 may be integrated in the head-mountable computing device 100 for this purpose.

The head-mountable computing device 100 may comprise at least one display module 106, under control of a discrete display controller (not shown). Alternatively, the display controller may be implemented by a processor 110 of the head-mountable computing device 100, as shown in Figure 2. The display module 106 may be a transparent or see- through display module. The display module may be a two-dimensional or a three- dimensional display module.

When present, the at least one display module 106 is typically arranged to cover the field of view of the wearer when the head-mountable computing device 100 is worn by the wearer such that a wearer of the head-mountable computing device 100 may observe the field of view through an image displayed on the at least one the display module 106. In an embodiment, the head-mountable computing device 100 comprises a pair of transparent display modules 106 including a first display module that can be observed by the right eye of the wearer and a second display module that can be observed by the left eye of the wearer. Alternatively, the at least one display module 106 may be a single display module covering both eyes of the wearer.

The at least one display module 106 may be provided in any suitable form, such as a transparent lens portion as shown in Figure 1 onto which an image is projected as is well-known per se. Alternatively, the head-mountable computing device 100 may comprise a pair of such a lens portions, i.e. one for each eye as explained above. The one or more transparent lens portions are dimensioned such that substantially the entire field of view of the wearer is obtained through the one or more transparent lens portions. For instance, the at least one display module 106 may be shaped as a lens to be mounted in a frame 125 of the head-mountable computing device 100 or a component housing 135 of the head-mountable computing device 100. Alternatively, the head-mountable computing device 100 may comprise an array of LEDs 106' as the display module 106 located on the frame 125 of the head-mountable computing device 100. The array of LEDs 106' may be controlled by the processor 110 of the head-mountable computing device 100.

The display module 106 may be controlled by the processor 110 to generate motion illusion information, such as a vection scene, a tunnel scene, or an optic flow scene. It is understood that other motion illusion information may be generated by the processor 110. In general, the moving elements representing the motion scene may move so as to generate an illusion of locomotion of the viewer, e.g., the illusion that the viewer is moving him/herself. Such a motion scene may be represented by a sequence of camera images obtained from a moving camera with respect to a static, or differently moving scene. For example, there may be an absence of non-moving, static elements. In a specific example, if the moving elements are represented by visual elements having a certain brightness, e.g., as generated by a display or one or more light emitting diodes, these moving elements may be surrounded by black, e.g., as generated by the display or represented by LEDs which are switched off or blank space between the LEDs. In another example, the moving elements themselves may be generated by sequentially over time switching display elements, e.g., pixels or LEDs, on while switching adjacent display elements off so as to generate the illusion that the element is moving. This technique of generating moving elements is well- known. In general, any motion scene which evokes the illusion of locomotion of the viewer may be used. It will be appreciated that such scenes may be differentiated from scenes which do not evoke the illusion of locomotion by a person skilled in the art of visual perception. Additionally or alternatively, simple perception experiments may indicate which scenes are suitable and which are not to evoke at the wearer the illusion of locomotion.

It will be understood that the frame 125 may have any suitable shape and may be made of any suitable material, e.g. a metal, metal alloy, plastics material or combination thereof. Several components of the head-mountable computing device 100 may be mounted in the frame 125, such as in the component housing 135 forming part of the frame 125. The component housing 135 may have any suitable shape, preferably an ergonomic shape that allows the head-mountable device 100 to be worn by its wearer in a comfortable manner.

The functioning of at least part of the head-mountable computing device 100 may be controlled by the processor 110 that executes instructions, i.e. computer program code, stored in a non-transitory computer readable medium, such as data storage 112. Thus, processor 110 in combination with processor-readable instructions stored in the data storage 112 may function as a controller of the head-mountable computing device 100. In addition to instructions that may be executed by the processor 110, the data storage 112 may store data that is associated with the generation of motion illusion information on the at least one display module 106.

In an embodiment, the head-mountable computing device 100 may be adapted to wirelessly communicate with a remote system, e.g. a further system 200 as shown in Figure 2. To this end, the head-mountable computing device 100 may include a wireless communication interface 102 for wirelessly communicating with a remote target such as the remote further system 200. Any suitable wireless communication protocol may be used for any of the wireless communication between the head-mountable computing device 100 and the remote system 200, e.g., an infrared link, Zigbee, Bluetooth, a wireless local area network protocol such as in accordance with the IEEE 802.11 standards, a 2G, 3G or 4G

telecommunication protocol, and so on. The remote further system 200 may for instance be controlled to provide the wearer of the head-mountable computing device 100 with feedback information and/or oral hygiene instructions, as will be further explained below. The wireless communication interface 102 may be configured for wirelessly communicating with a further remote system, e.g. a wireless LAN, through which the head-mountable computing device 100 may access a remote data source such as the Internet, for instance to store data such as user preferences, user specific information, and so on. Alternatively, the head-mountable computing device 100 may include one wireless communication interface that is able to communicate with the remote further system 200 and a further remote target such as the further network. The processor 110 may further be adapted to control wireless

communication interface 102.

In an embodiment, the head-mountable computing device 100 may be arranged to detect a user instruction and to trigger an operation in response to the detected user instruction, e.g. using at least one further sensor 146 including a motion sensor like a gyroscope or similar in case the user instruction is a head motion, or by using an image sensor 114 or a camera to capture an image of a gesture-based instruction made by the wearer. Other suitable sensors for such gesture or motion capturing will be apparent to the skilled person. The processor 110 may be arranged to recognize a gesture or motion made by its wearer from the captured sensor data and to interpret the recognized gesture or motion as an instruction, for instance to identify a task performed by the wearer of the head-mountable computing device 100, e.g., reading, computing, and so on. Non- limiting examples of such a motion for instance include a turn or nod of the wearer's head. Non- limiting examples of such a gesture for instance include a hand or finger gesture in the field of view through the head-mountable computing device 100, which may be detected in an image captured with the image sensor 114. Alternatively or additionally, the at least one further sensor 146 may include a sound sensor, e.g. a microphone, may be present to detect a spoken instruction, wherein the processor 110 may be communicatively coupled to the further sensor in order to process the sensor data and detect the spoken instruction. The at least one further sensor 146 may additionally or alternatively include an input sensor, e.g. a button or the like for facilitating the wearer of the head-mountable computing device 100 to select the user instruction from a list of options. Such list of options for instance may be displayed on the at least one transparent display module 106 of the head-mountable computing device 100, when present. The head-mountable computing device 100 may further include a user interface 108 for receiving input from the user. User interface 108 may include, for example, a touchpad, a keypad, buttons, a microphone, and/or other input devices. The processor 110 may control at least some of the functioning of head-mountable computing device 100 based on input received through user interface 108. In some embodiments, the at least one further sensor 118 may define or form part of the user interface 108.

In an embodiment, the head-mountable computing device 100 may comprise a Transcutaneous Electrical Nerve Stimulation (TENS) subsystem 132 and/or an amplifier 104 as additional medium stimulation. The amplifier 104 may provide audio signals to the wearer in order to enhance the motion illusion information. The TENS subsystem 132 may also provide stimulation to enhance the motion illusion information.

In an embodiment, the head-mountable computing device 100 may comprise a motion sensor 116 as the physical activity sensor for detecting the wearer's current activity. The image sensor 114 may also be used as the physical activity sensor for detecting the wearer's current activity. The image sensor 114 is configured for capturing an image or video data or signals in a field of view of a wearer of the head-mountable computing device 100. Such captured image or video data or signals may be used for analyzing the activity of the wearer. Alternatively, other electronic devices including a camera may be used for capturing the image or video data or signals from an area including the wearer of the wearable computing device. Examples of such electronic devices may be hand-held devices such as a smartphone, a tablet, etc., other head-mountable computing device, a surveillance device such as an alarm camera mounted in a room, or a vital sign monitoring device such as a device including a vital signs camera used for remote photo-plethysmography. In an embodiment, the head-mountable computing device 100 may comprise a temperature sensor 118 for measuring the core body temperature (CBT) of the wearer. The temperature sensor 118 may be a skin temperature sensor.

In an embodiment, the head-mountable computing device 100 may comprise a ECG sensor and/or a PPG sensor 122 for measuring the heartbeat of the wearer of the head- mountable computing device 100.

In an embodiment, the head-mountable computing device 100 may comprise a subprocessor 122 configured for executing instructions, i.e. computer program code, stored in a non-transitory computer readable medium, such as data storage 112. Thus, the subprocessor 122 in combination with processor-readable instructions stored in the data storage 112 may function as a controller of the head-mountable computing device 100. The data storage 112 may store a mathematical model of the human Circadian pacemaker to be executed by the subprocessor 122 for determining the current circadian phase based on data derived from a light sensor 126 and a motion sensor 116 as input.

In an embodiment, the head-mountable computing device 100 may comprise a satellite positioning systems 124, such as GPS or GLONASS, for deriving the current geo- position of the wearer and the time-of-year information so as to determine the phase of the current solar cycle of the wearer of the head-mountable computing device 100.

In an embodiment, the head-mountable computing device 100 may comprise an optical filter 128 for removing excess light stimulus when the display module is displaying motion illusion scene, and a light source 130 for emitting an additional light stimulus to the circadian system when the display module is displaying motion illusion scene.

Although Figure 2 shows various components of head-mountable computing device 100 as being separate from the at least one display module 106, one or more of these components may be mounted on or integrated into the at least one display module 106. For example, an image sensor 114 may be mounted on a see-through display module 106, user interface 108 could be provided as a touchpad on a see-through display module 106, processor 110 and data storage 112 may make up a computing system in a see-through display module 106, and the other components of head-mountable computing device 100 could be similarly integrated into a see-through display module 106.

Alternatively, the head-mountable computing device 100 may be provided in the form of separate devices that can be worn on any part of the body or carried by the wearer, apart from at least the one display module 106, which typically will be mounted on the head. The separate devices that make up head-mountable computing device 100 may be communicatively coupled together in either a wired or wireless fashion.

In operation, the first type of sensor 142 provides sensor readings to the processor 110, from which the processor 110 determines the phase of the current circadian rhythm of the wearer. The processor 110 for instance may be adapted to process the raw sensor signals related to the body temperature of the wearer in order to determine the phase of the current circadian rhythm of the wearer. For this purpose, the processor 110 stores the acquired measureed body temperature for the past 24 hours and determines the minimum of the body temperature within the stored data. The time of the minimum determines the circadian phase of the wearer. Alternatively, the processor 110 for instance may be adapted to process the raw sensor signals related to the heartbeat measurement, such as ECG signals measured by an ECG sensor, or PPG signal measured by a PPG sensor, in combination with raw sensor signals related to the identification of the physical activity of the wearer. The methods which can be used by the processor 110 to derive circadian phase information from the raw sensor data including heartbeat measurements are well-known and are not further described here. One example of the method of deriving circadian phase information from the raw sensor data including heartbeat measurements is disclosed by Gil EA et al. in "Human circadian phase estimation from signals collected in ambulatory conditions using an autoregressive model" J Biol Rhythms. 2013 Apr;28(2): 152-63. Alternatively, at least some of the processing of the raw sensor signals may be performed by the first type of sensor 142, such that the processor 110 is provided with (pre-)processed sensor signals, namely the result of the current circadian rhythm of the wearer.

Meanwhile, the second type of sensor 144 provides sensor readings to the processor 110, from which the processor 110 determines the phase of the current solar cycle. The processor 110 for instance may be adapted to process the raw sensor signals related to the current geo-position of the wearer and the time-of-year information so as to determine the phase of the current solar cycle. Method and algorithms for calculating sun rise and sunset based on geolocation and time are well known as for instance disclosed by

https://en.wikipedia.org/wiki/Sunrise_equation, and not further described here. Alternatively, the processor 110 for instance may be adapted to process the raw sensor signals related to the variation of the ambient light intensity and is therefore capable to determine the current solar cycle. This is done by low-pass filtering the ambient light levels and comparing them against a threshold to determine the time of sunrise and sunset. Alternatively, at least some of the processing of the raw sensor signals may be performed by the second type of sensor 144, such that the processor 110 is provided with (pre-)processed sensor signals, namely the result of the current solar cycle.

Upon the determination of the current circadian rhythm of the wearer and the current solar cycle, the motion illusion information displayed on the display module 106 may be adjusted by the processor 110. The processor for instance may be adapted to extend the duration of the motion illusion information if the discrepancy between the current solar cycle and the current circadian rhythm of the wearer is increased. Alternatively, the processor 110 for instance may be adapted to update or change the content of the motion illusion information.

In an embodiment, the head-mountable computing device 100 may be configured to repeat the above described determination of the current solar cycle and the current circadian rhythm of the wearer, and adjust the motion illusion information accordingly upon the head-mountable computing device 100 is initialized by the wearer.

Figures 3A-3D show different embodiment of the current invention that motion illusion information may be provided to the wearer of the head-mountable computing device 100.

In Figure 3 A, after the head-mountable computing device 100 is manually switched on by the wearer in step 301, motion illusion information is provided to the wearer controlled by the processor 110, in step 303, such that neurochemical signals may be generated by the brain of the wearer.

In Figure 3B, after the head-mountable computing device 100 is manually switched on by the wearer in step 31 1, motion illusion information is provided to the wearer controlled by the processor 110, in step 313, such that neurochemical signals may be generated by the brain of the wearer. Simultaneously, in step 315, the current circadian rhythm of the wearer is sensed by the temperature sensor 118, and the current solar cycle is sensed by the light sensor 126. Based on the current circadian rhythm of the wearer and the current solar cycle, the processor 110 is adapted to determine a desired phase shift of the wearer in step 317. Based on the determined desired phase shift, the motion illusion information is updated by the processor 110.

In Figure 3C, after the head-mountable computing device 100 is manually switched on by the wearer in step 321, motion illusion information is provided to the wearer controlled by the processor 110, in step 323, such that neurochemical signals may be generated by the brain of the wearer. Simultaneously, in step 325, the current circadian rhythm of the wearer is sensed by the temperature sensor 118, and the current solar cycle is sensed by the light sensor 126. Based on the current circadian rhythm of the wearer and the current solar cycle, the processor 110 is adapted to determine a desired phase shift of the wearer in step 327 as well as an optimal period of the motion illusion information in step 329. Based on the determined desired phase shift, the motion illusion information is updated by the processor 110. The processor 110 may be adapted to terminate the displaying of the motion illusion information based on the optimal period of the motion illusion information.

In Figure 3D, in step 331, the motion illusion information is automatically started by the processor 110 by taking into account the data received from the light sensor 126. Here, the data received from light sensor 126 may be used for 1) determining the current solar cycle; 2) determining the current light level; and/or 3) determining whether the current solar cycly is dawn or dusk. Preferrably, the motion illusion information may be

automatically provided to the wearer controlled by the processor 110 only if 1) there is a discrepancy between the current solar cycle and the current circadian rhythm of the wearer, wherein the current solar cycle may be measured by the light sensor; 2) the current light levels are consistent with the required light levels, wherein the required light levels may be measured by the light sensor; and 3) the current solar cycle is dawn or dusk, wherein the current solar cycle may be measured by the light sensor. Accordingly, in step 333, motion illusion information is provided to the wearer controlled by the processor 110 such that neurochemical signals may be generated by the brain of the wearer. Simultaneously, in step 335, the current circadian rhythm of the wearer is sensed by the temperature sensor 118, and the current solar cycle is sensed by the light sensor 126. Based on the current circadian rhythm of the wearer and the current solar cycle, the processor 110 is adapted to determine a desired phase shift of the wearer in step 337 as well as an optimal period of the motion illusion information in step 339. Based on the determined desired phase shift, the motion illusion information is updated by the processor 110. The processor 110 may be adapted to terminate the displaying of the motion illusion information based on the optimal period of the motion illusion information.

The processor 110 may implement a method 400 for providing motion illusion information in the flow chart of Figure 4a. The method 400 commences in step 401, after the head-mountable computing device 100 is switched on, initializing the display module 106, after which the method 400 progresses to step 403 in which motion illusion information to a wearer of the head-mountable computing device is displayed.

Alternatively, the processor 110 may implement a method 410 for providing motion illusion information in the flow chart of Figure 4b. The method 400 commences in step 411, after the head-mountable computing device 100 is switched on, initializing the display module 106, after which the method 410 progresses to step 413 in which motion illusion information to a wearer of the head-mountable computing device is displayed, after which the method 410 progreses to step 415 in which the measured data indicative of the phase of the current circadian rhythm of the wearer is received from the first type of sensor and the measured data indicative of the current solar cycle is received from the second type of sensor; after which the method 410 progreses to step 417 in which the phase of the current circadian rhythm of the wearer and the phase of the current circadian rhythm of the wearer are determined; after which the method 410 progreses to step 419 in which the phase of the current circadian rhythm of the wearer with the phase of the current solar cycle are compared; after which the method 410 progreses to step 421 in which the displayed motion illusions information is adjusted based on the comparison result of the phase of the current circadian rhythm of the wearer and the phase of the current solar cycle.

It should be understood that the embodiment of the methods 400 and 410 as shown in the flowchart of Figures 4a and 4b respectively are non- limiting examples of this embodiment, and that many alterations of this method may be made without departing from the present invention.

The generation of glucocorticoids will be effective in adjusting the brain's pacemaker during episodes of dawn and dusk in the timeframe of the observer's biological clock. To be more specific, when a person just completed a transatlantic flight from Boston to Paris, the device will be effective during epochs of dawn and dusk in the Boston timeframe as is depicted in Figure 5. The wearer could use the head-mountable computing device already a couple of days before departure to already adjust the beginning and end of the circadian cycle in the correct direction (towards the destination cycle). During a transatlantic flight it could be used to adjust the beginning and end of the current dawn and dusk periods of the current circadian rhythm of the wearer. In the hotel room at the destination, it could be further used to bridge the remaining time difference between the current circadian rhythm of the wearer and the solar cycle at destination.

Aspects of the present invention may be embodied as a wearable computing device, method or computer program product. Aspects of the present invention may take the form of a computer program product embodied in one or more computer-readable medium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Such a system, apparatus or device may be accessible over any suitable network connection; for instance, the system, apparatus or device may be accessible over a network for retrieval of the computer readable program code over the network. Such a network may for instance be the Internet, a mobile communications network or the like. More specific examples (a non- exhaustive list) of the computer readable storage medium may include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of the present application, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Computer program code for carrying out the methods of the present invention by execution on the processor 110 may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the processor 1 10 as a stand-alone software package, e.g. an app, or may be executed partly on the processor 1 10 and partly on a remote server. In the latter scenario, the remote server may be connected to the head-mountable computing device 100 through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer, e.g. through the Internet using an Internet Service Provider.

Aspects of the present invention are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions to be executed in whole or in part on the processor 110 of the head-mountable computing device 100, such that the instructions create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer program instructions may also be stored in a computer-readable medium that can direct the head-mountable computing device 100 to function in a particular manner.

The computer program instructions may be loaded onto the processor 110 to cause a series of operational steps to be performed on the processor 110, to produce a computer-implemented process such that the instructions which execute on the processor 110 provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. The computer program product may form part of a head-mountable computing device 100, e.g. may be installed on the head-mountable computing device 100.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several distinct elements. In the device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.