CN115525143A

CN115525143A - Eyeball movement tracking method based on contact lenses and contact lenses

Info

Publication number: CN115525143A
Application number: CN202110990930.6A
Authority: CN
Inventors: 张文菁
Original assignee: Shenzhen Zhiyao Culture Technology Co ltd
Current assignee: Shenzhen Xianshun Technology Co.,Ltd.
Priority date: 2021-08-26
Filing date: 2021-08-26
Publication date: 2022-12-27

Abstract

The invention discloses an eyeball movement tracking method based on contact lenses and the contact lenses, wherein the contact lenses comprise: the far-eye film, the near-eye film and the middle layer arranged between the far-eye film and the near-eye film are arranged, and the middle layer comprises an inertial sensor and a main control unit electrically connected with the inertial sensor; the inertial sensor comprises an MEMS acceleration sensing chip, an MEMS angular velocity sensing chip and a Hall magnetometer chip, and the MEMS acceleration sensing chip transmits detected acceleration data to the main control unit; the MEMS angular velocity sensing chip acquires the angular velocity data of eyeball movement and transmits the data to the main control unit; the Hall magnetometer chip transmits geomagnetic data to the main control unit at intervals of preset time, the main control unit calculates eyeball motion tracks according to the acceleration data, the angular velocity data and the geomagnetic data, and the eyeball motion tracks are transmitted to the mobile terminal. The contact lens is light and portable, can detect eye movement in daily life, and realizes high-precision eyeball movement tracking.

Description

Eyeball movement tracking method based on contact lenses and contact lenses

Technical Field

The invention relates to the technical field of eye movement tracking, in particular to an eyeball movement tracking method based on contact lenses and the contact lenses.

Background

The human eye movement tracking technology has wide application scenes, including medical health, human-computer interaction, marketing, online education and the like. Accurate and rapid eye tracking equipment can assist scientific research on a visual system and has commercial value. Currently, several methods for tracking the eyeball exist.

Conventional eye tracking techniques include Video oculography (visual oculography) based optical techniques such as directing a beam of infrared light and a camera at the eye and tracking eye movements by back-end analysis of corneal reflections. The high sampling rate eye tracker in this way has the advantage of high accuracy. Another approach is to monitor the change in the periocular potential by applying electrode pads around the eye. This method is not limited by light-line elements and can be used to track eye movements during sleep. The electro-oculogram (electrooculogram) is drawn to accurately detect the eye jump (saccade) and blink (blink) movements, but is insensitive to the direction of eye movement. In summary, the conventional eye tracking technology is only suitable for basic interaction, but not for advanced interaction which may appear in the future.

The conventional eyeball tracking technology has the following disadvantages: the helmet or the electrode plate needs to be worn, or the remote camera captures eye movements, so that the device is large in size and heavy in weight, the movement of a user is limited, and the eye movement cannot be detected in normal life.

In order to break through the obstacles of the traditional mode, the novel technology embeds devices such as capacitors or optical sensors into contact lenses so as to track the positions of the sight line and the eyeballs relative to the head. The prior proposal of putting a capacitance or a light sensor into the contact lens can not directly measure the speed, can only deduce through displacement, can only measure the movement of eyeballs relative to the head, can not track the movement of the eyeballs in free space, and often requires complex optical devices and high resolving power of a computer, and has higher cost.

Therefore, the eyeball tracking technology is based on indirect measurement through optical signals or electric signals, rather than direct measurement, is prone to interference, generates system errors, limits accuracy, can only track the position of the eyeball relative to the head, and cannot track the position of the eyeball in a three-dimensional free space.

Accordingly, the prior art is yet to be improved and developed.

Disclosure of Invention

In view of the above disadvantages of the prior art, the present invention provides an eye movement tracking method based on contact lenses and contact lenses, which aims to solve the problem of large system error when the contact lenses in the prior art track the eye movement.

The technical scheme of the invention is as follows:

a first embodiment of the invention provides a contact lens, the method comprising: the method comprises the following steps: the near-eye mask comprises a far-eye film, a near-eye film and an intermediate layer arranged between the far-eye film and the near-eye film, wherein the intermediate layer comprises an inertial sensor and a main control unit electrically connected with the inertial sensor;

the inertial sensor is used for acquiring acceleration, angular velocity and geomagnetic data during eyeball movement and transmitting the acceleration, the angular velocity and the geomagnetic data to the main control unit when the eyeball movement is detected; the main control unit is used for calculating an eyeball movement track according to the acceleration data, the angular velocity data and the geomagnetic data and transmitting the eyeball movement track to the mobile terminal;

the inertial sensor comprises an MEMS acceleration sensing chip, an MEMS angular velocity sensing chip and a Hall magnetometer chip, wherein the speed sensor, the MEMS angular velocity sensing chip and the Hall magnetometer chip are respectively and electrically connected with the main control unit;

the MEMS acceleration sensing chip is used for detecting the eyeball motion state and transmitting the detected acceleration data to the main control unit;

the MEMS angular velocity sensing chip is used for acquiring angular velocity data of eyeball movement when the eyeball movement is detected and transmitting the angular velocity data to the main control unit;

the Hall magnetometer chip is used for acquiring geomagnetic data and transmitting the geomagnetic data to the main control unit at preset time intervals.

Furthermore, the main control unit is further configured to correct the angular velocity data according to the acquired geomagnetic data.

Furthermore, the MEMS acceleration sensing chip, the MEMS angular velocity sensing chip and the Hall magnetometer chip are equidistantly distributed on a circle which is at a preset distance from the center point of the contact lens, so that the weight of each sensor chip is balanced.

Further, the main control unit is also used for controlling and stopping the counting of the MEMS angular velocity sensing chip and the Hall magnetometer chip when the acceleration data is detected to be kept at a preset gravity acceleration value and the angular velocity data is zero, so that the MEMS angular velocity sensing chip and the Hall magnetometer chip are in a standby state.

Further, the main control unit is further configured to acquire initial acceleration data sent by the MEMS acceleration sensing chip when the eyeball is in a stationary state, where the initial acceleration data is a value of gravitational acceleration.

Further, the peripheral edge of the distal membrane and the peripheral edge of the proximal membrane both extend beyond the peripheral edge of the intermediate layer and the peripheral edges of the distal membrane and the proximal membrane are in sealing contact.

Further, the hardness of the near-eye membrane is smaller than that of the far-eye membrane.

Further, the outer eye membrane and the near eye membrane are divided into a pupil area and a non-pupil area, and the MEMS acceleration sensing chip, the MEMS angular velocity sensing chip and the Hall magnetometer chip are arranged in the non-pupil area.

Another embodiment of the present invention provides an eye movement tracking method for the contact lens, the method comprising:

the MEMS acceleration sensing chip detects acceleration data of eyeballs and transmits the acceleration data to the main control unit;

the main control unit detects acceleration data to wake up the MEMS angular velocity sensing chip and the Hall magnetometer chip;

the MEMS angular velocity sensing chip acquires angular velocity data of eyeball movement and transmits the angular velocity data to the main control unit;

the Hall magnetometer chip acquires geomagnetic data and transmits the geomagnetic data to the main control unit at preset time intervals;

the main control unit corrects the angular velocity data according to the geomagnetic data, obtains corrected angular velocity data and records the corrected angular velocity data as target angular velocity data;

the main control unit calculates eyeball motion tracks according to the acceleration data, the target angular velocity data and the geomagnetic data and transmits the eyeball motion tracks to the mobile terminal.

Further, the main control unit calculates an eyeball movement track according to the acceleration data, the target angular velocity data and the geomagnetic data, and transmits the eyeball movement track to the mobile terminal, and then the method further comprises the following steps:

and when the main control unit detects that the acceleration data is kept at a preset gravity acceleration value and the angular velocity data is zero, the main control unit controls to stop counting the MEMS angular velocity sensing chip and the Hall magnetometer chip, so that the MEMS angular velocity sensing chip and the Hall magnetometer chip are in a standby state.

Has the advantages that: the contact lens provided by the embodiment of the invention is light and portable, has low wearing sense, does not affect the facial image, can detect eye movement in daily life, realizes high-precision eyeball movement tracking, can track the position of eyeballs in a free three-dimensional space, and can directly detect the speed of eyeball movement.

Drawings

The invention will be further described with reference to the following drawings and examples, in which:

FIG. 1 is a schematic diagram of a preferred embodiment of a contact lens of the present invention;

FIG. 2 is a functional block diagram of the intermediate layer of a preferred embodiment of a contact lens of the present invention;

FIG. 3 is a schematic diagram of a coordinate system of a preferred embodiment of a contact lens of the present invention;

FIG. 4 is a flowchart illustrating a method for tracking eye movement based on contact lenses according to a preferred embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and effects of the present invention clearer and clearer, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

Embodiments of the present invention are described below with reference to the accompanying drawings.

The embodiment of the invention provides a functional structure schematic diagram of a contact lens, as shown in fig. 1, fig. 2 and fig. 3, the contact lens comprises a near-eye membrane 1, a far-eye membrane 3, and an intermediate layer 2 arranged between the far-eye membrane 3 and the near-eye membrane 1, the intermediate layer comprises an inertial sensor and a main control unit 22 electrically connected with the inertial sensor;

the inertial sensor comprises an MEMS acceleration sensing chip 21, an MEMS angular velocity sensing chip 23 and a Hall magnetometer chip 24, wherein the speed sensor, the MEMS angular velocity sensing chip and the Hall magnetometer chip are respectively and electrically connected with the main control unit;

and the Hall magnetometer chip is used for acquiring geomagnetic data and transmitting the geomagnetic data to the main control unit at preset time intervals.

In particular implementations, the contact lenses of embodiments of the present invention include, but are not limited to, a far-eye membrane, a near-eye membrane, and an intermediate layer, the intermediate layer being provided with three inertial sensors (a MEMS acceleration sensing chip, a MEMS angular velocity sensing chip, and a hall magnetometer chip, respectively) and a master control unit. The inertial sensor is connected to the main control unit by two copper wires respectively, wherein one is a clock wire, and the other is a data wire. The power and ground lines are shared by the three inertial sensors and the master control unit (not shown in the figure). The three sensors and the main control unit are all positioned in the middle layer and do not protrude out of the upper surface or the lower surface, so that the cornea and the eyelid are prevented from being scratched.

The MEMS acceleration sensing chip measures the acceleration and the gravity acceleration of the eyeball, records eyeball movement events and transmits data to the main control unit. The MEMS acceleration sensing chip generally adopts an accelerometer, the accelerometer is a triaxial MEMS accelerometer, and a typical product has mCube MC3672 with the size of 1.1mmx1.3mm (with packaging).

The MEMS angular velocity sensing chip measures angular velocity, restores eyeball angular motion (six basic motions of outward rotation, inward rotation, upward rotation, downward rotation, inward rotation, outward rotation and the like), and transmits data to the main control unit. A gyroscope is adopted in a further MEMS angular velocity sensing chip. The gyroscope is generally a three-axis MEMS gyroscope, typical products comprise invensense IAM-20380, NXP FXAS21002CQ and the like, and the size of the gyroscope is generally 3mmx3mmx0.7mm (the package is 4 mmx4mmx1.3mm).

The Hall magnetometer chip detects the direction and intensity of the geomagnetic field, and transmits data to the main control unit every a seconds of movement (typical value is between 1s and 2 s). Further, the hall magnetometer chip may employ a magnetometer. c) Magnetometer: a typical product, typically a three-axis hall magnetometer, has AKM AK09915 with a size of 1.6mmx1.6mmx0.5mm (with encapsulation).

There are many chips on the market with the above three sensors combined, such as mCube MC6470 ecopass, which contains magnetometer and accelerometer, and also analog gyroscope output. There are many kinds, not one by one.

The main control unit performs three functions of control, resolving, communication and power supply. The main control unit calculates eyeball movement tracks according to the acceleration, the angular velocity and the geomagnetic direction and transmits data to the mobile terminal. The communication and power supply can use the prior art, the embodiment of the invention is not described, and in addition, the mobile terminal is an intelligent electronic device, including but not limited to a mobile phone, a tablet computer and the like.

The solution of incorporating a capacitive or optical sensor in the contact lens does not allow direct measurement of the speed, can only be derived from the displacement, and can only measure the movement of the eye relative to the head, and cannot track the movement of the eye in free space. Complex optics and high computer resolution are often required, and the cost is high. The embodiment of the invention adopts the MEMS acceleration sensing chip, the MEMS angular velocity sensing chip, the Hall magnetometer chip and the like to realize the direct measurement of the angular velocity, and the method is simple and has high accuracy.

In some other embodiments, the wires are generally arranged in close proximity to the outer edge of the lens, without affecting the field of view, but the adjustment may be modified as appropriate. The wire material can be copper wire or other conductive materials; an integrated chip can be used, and two sensors are combined on the same chip, so that the space is saved, and the length of a lead is shortened.

The contact lenses of the embodiments of the invention can be used to detect driver fatigue and distraction by tracking eye movement; rehabilitation and auxiliary applications such as wheelchair control, etc.; to aid in text reading on AR contact lenses, and the like.

Further, the main control unit is further configured to correct the angular velocity data according to the acquired geomagnetic data.

In specific implementation, in the prior art, because the scheme of placing the capacitance or the optical sensor in the contact lens only has one sensing mode, when a system error occurs, the deviation cannot be corrected in a multi-sensing fusion mode. In the invention, the magnetometer is used for detecting the direction of the geomagnetic field, and data is transmitted to the main control unit every a seconds of movement (the typical value a is between 1s and 2 s), and the main control unit corrects the data of the gyroscope to avoid error accumulation.

The specific method for correcting the gyroscope by the magnetometer comprises the following steps:

the formula derived below can be used to calibrate the yaw angle of the gyroscope using the magnetometer. Aiming at the movement characteristics of the eyeballs, the yaw of the gyroscope is only calibrated when the eyeballs move horizontally.

Assuming the raw magnetometer measures readings when the eyeball is in a particular position, the raw magnetometer is assumed to read

The quaternion of magnetometer coordinate system m versus eye coordinate system h (see FIG. 3) is expressed as

Its rotation matrix is then:

further, the magnetic field vector (normalized) in the eye coordinate system is:

to calculate the yaw vector, a reference position is first specified. It is assumed that the x-axis (perpendicular to the iris pointing out of the eye) of the eye coordinate system points to the north direction of the earth magnetism as a reference position, and the z-axis point coincides with the gravity point, so that the y-axis magnetic force index is 0. Thus, the ideal magnetic field vector in the eye coordinate system at this position is:

further, for a magnetometer, the ideal reading at this time would be:

the cross product of the raw and ideal readings from the magnetometer is the horizontal angle error value:

ε _m i.e. the yaw value of the horizontal angle of the gyroscope.

Furthermore, the MEMS acceleration sensing chip, the MEMS angular velocity sensing chip and the Hall magnetometer chip are equidistantly distributed on a circle which is at a preset distance from the center point of the contact lens.

In specific implementation, the three inertial sensors are distributed on a circle with a distance r from the central point of the contact lens, and the included angle is 120 degrees so as to ensure that the weight is uniformly distributed. The central part of the visual field is not occupied, and the user can observe objects conveniently.

Further, the main control unit is also used for controlling and stopping counting of the MEMS angular velocity sensing chip and the Hall magnetometer chip when the acceleration data is detected to be kept at a preset gravity acceleration value and the angular velocity data is zero, so that the MEMS angular velocity sensing chip and the Hall magnetometer chip are in a standby state.

When the MEMS acceleration sensing chip is specifically implemented, when the data of the MEMS acceleration sensing chip is kept at the gravity acceleration, the reading of the gyroscope is zero, and the reading of the magnetometer is close to zero, the counting of the gyroscope and the magnetometer is stopped, the data is initialized, and the system returns to a standby state.

During specific implementation, if the eyeball is in a static state, if the MEMS acceleration sensing chip judges that the acceleration is constant, the gravity acceleration is recorded, the system is in a standby state at the moment, and the gyroscope and the magnetometer do not work at the moment so as to reduce the energy consumption of the system.

When the reading of the MEMS acceleration sensing chip obviously deviates from the gravity acceleration, a signal is transmitted to the main control chip, and the gyroscope and the magnetometer are awakened.

Further, the peripheral edge of the distal membrane and the peripheral edge of the proximal membrane both extend beyond the peripheral edge of the intermediate layer, and the peripheral edges of the distal membrane and the proximal membrane are in sealing contact.

When the eyeball protective device is specifically implemented, the contact of the middle layer with the eyeball can be avoided, the eyeball is protected from being damaged by the middle layer, the influence of the external environment on the middle layer can be prevented, and the use function of the middle layer is also protected

When the eye protection device is specifically implemented, the near-eye membrane can be set to be a software membrane layer, the far-eye membrane is provided with a hard membrane layer, and the soft membrane layer is close to the eyeball, so that the eyeball can be further protected from being damaged. The hard film layer can effectively maintain the shape stability of the contact lens.

Furthermore, the outer eye membrane and the near eye membrane are divided into a pupil area and a non-pupil area, and the MEMS acceleration sensing chip, the MEMS angular velocity sensing chip and the Hall magnetometer chip are all arranged in the non-pupil area.

In specific implementation, in order to prevent the visual field of a user from being influenced, the outer eye membrane and the near eye membrane are divided into a pupil area and a non-pupil area, and the MEMS acceleration sensing chip, the MEMS angular velocity sensing chip and the Hall magnetometer chip are all arranged in the non-pupil area, so that the visual field freedom can be ensured in tracking the eyeball movement direction.

The contact lens provided by the embodiment of the invention is light and portable, has low wearing sense, does not influence the facial image, and can detect eye movement in daily life; high-precision eyeball motion tracking is realized; the sensor is rigidly connected with the eyeball under an ideal state on the contact lens, and the system motion and the eyeball motion are completely synchronous; the tracking of the inertial sensor is not affected by head movements; mutual rectification can be realized among the MEMS acceleration sensing chip, the gyroscope and the magnetometer.

The eyeball motion track and the motion state relative to the inertial system can be directly measured in the three-dimensional free space, and the method is not limited to the motion relative to the head.

The used materials are less, the energy consumption is less, and the cost is reduced.

Referring to fig. 4, fig. 4 is a flowchart illustrating an eye movement tracking method based on contact lenses according to a preferred embodiment of the present invention. As shown in fig. 1, it comprises the steps of:

s100, detecting acceleration data of an eyeball by an MEMS acceleration sensing chip and transmitting the acceleration data to a main control unit;

s200, the main control unit detects acceleration data to wake up an MEMS angular velocity sensing chip and a Hall magnetometer chip;

s300, acquiring angular velocity data of eyeball movement by an MEMS angular velocity sensing chip, and transmitting the angular velocity data to a main control unit;

step S400, the Hall magnetometer chip acquires geomagnetic data and transmits the geomagnetic data to the main control unit at preset time intervals;

step S500, the main control unit corrects the angular velocity data according to the geomagnetic data, obtains the corrected angular velocity data and records the corrected angular velocity data as target angular velocity data;

and step S600, the main control unit calculates an eyeball motion track according to the acceleration data, the target angular velocity data and the geomagnetic data and transmits the eyeball motion track to the mobile terminal.

In specific implementation, when the system works: if the eyeball is in a static state, if the MEMS acceleration sensing chip judges that the acceleration is constant, the acceleration is recorded as the gravity acceleration, the system is in a standby state at the moment, and the gyroscope and the magnetometer do not work at the moment so as to reduce the energy consumption of the system. When the reading of the MEMS acceleration sensing chip obviously deviates from the gravity acceleration, a signal is transmitted to the main control chip, and the gyroscope and the magnetometer are awakened. The gyroscope reads angular motion information, and transmits real-time data to the main control chip for processing, so that the speed and the track of eyeball motion are restored. In the process, the acceleration information of the MEMS acceleration sensing chip is read simultaneously, and the acceleration information and the angular velocity information are complementary. When the eyeball movement duration exceeds the preset time a seconds, the geomagnetic direction data judged by the magnetometer is transmitted to the main control chip, the gyroscope reading is smoothed and corrected, and no matter what movement mode the system is in, systematic deviation cannot be generated.

The ring-shaped wiring connects the respective portions so as not to affect the user's view. And judging whether to awaken the gyroscope and the magnetometer according to the standard that whether the reading of the MEMS acceleration sensing chip deviates from the gravity acceleration or not. The angular velocity of the eyeball is measured using a gyroscope for recovering the angular motion. And (5) regularly judging the geomagnetic direction by using the magnetometer, and correcting the drift of the gyroscope. And judging whether to recover to a standby mode or not according to the conditions that the angular velocity of the gyroscope is zero, the reading of the magnetometer is close to zero and the acceleration sensing chip of the MEMS is the standard of the gravity acceleration.

In one embodiment, after the main control unit calculates an eye movement trajectory according to the acceleration data, the target angular velocity data, and the geomagnetic data, and transmits the eye movement trajectory to the mobile terminal, the method further includes:

The above-described embodiments are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

Conditional language such as "can," "might," or "may" is generally intended to convey that a particular embodiment can include (yet other embodiments do not include) particular features, elements, and/or operations, among others, unless specifically stated otherwise or understood otherwise within the context as used. Thus, such conditional language is also generally intended to imply that features, elements and/or operations are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without input or prompting, whether these features, elements and/or operations are included or are to be performed in any particular embodiment.

What has been described herein in the specification and drawings includes examples that can provide an eye movement tracking method and apparatus. It will, of course, not be possible to describe every conceivable combination of components and/or methodologies for purposes of describing the various features of the present disclosure, but it can be appreciated that many further combinations and permutations of the disclosed features are possible. It is therefore evident that various modifications can be made to the disclosure without departing from the scope or spirit thereof. In addition, or in the alternative, other embodiments of the disclosure may be apparent from consideration of the specification and drawings and from practice of the disclosure as presented herein. It is intended that the examples set forth in this specification and the drawings be considered in all respects as illustrative and not restrictive. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A contact lens, comprising: the far-eye film, the near-eye film and the middle layer arranged between the far-eye film and the near-eye film are arranged, and the middle layer comprises an inertial sensor and a main control unit electrically connected with the inertial sensor;

the MEMS angular velocity sensing chip is used for acquiring angular velocity data of eyeball movement when the eyeball movement is detected, and transmitting the angular velocity data to the main control unit;

2. The contact lens of claim 1, wherein the main control unit is further configured to modify the angular velocity data based on the acquired geomagnetic data.

3. The contact lens of claim 1, wherein the MEMS acceleration sensing chip, the MEMS angular velocity sensing chip and the hall magnetometer chip are equidistantly distributed on a circle at a predetermined distance from a center point of the contact lens to balance the weight of each sensor chip.

4. The contact lens of claim 1, wherein the main control unit is further configured to control to stop counting the MEMS angular velocity sensing chip and the hall magnetometer chip when detecting that the acceleration data is maintained at the predetermined gravitational acceleration value and the angular velocity data is zero, so that the MEMS angular velocity sensing chip and the hall magnetometer chip are in a standby state.

5. The contact lens of claim 4, wherein the main control unit is further configured to obtain initial acceleration data sent by the MEMS acceleration sensing chip when the eyeball is in a resting state, wherein the initial acceleration data is a value of gravitational acceleration.

6. The contact lens of claim 1, wherein the peripheral edge of the distal membrane and the peripheral edge of the proximal membrane both extend beyond the peripheral edge of the intermediate layer and the peripheral edges of the distal membrane and the proximal membrane are in sealing contact.

7. The contact lens of claim 1, wherein the hardness of the near-eye membrane is less than the hardness of the far-eye membrane.

8. The contact lens of claim 1, wherein the outer-eye membrane and the near-eye membrane are each divided into a pupillary region and a non-pupillary region, the MEMS acceleration-sensing chip, the MEMS angular velocity-sensing chip, and the hall magnetometer chip all being disposed in the non-pupillary region.

9. A method for tracking eye movement based on the contact lens of any one of claims 1 to 8, the method comprising:

the MEMS acceleration sensing chip detects acceleration data of the eyeball and transmits the acceleration data to the main control unit;

the main control unit calculates an eyeball movement track according to the acceleration data, the target angular velocity data and the geomagnetic data, and transmits the eyeball movement track to the mobile terminal.

10. The method for tracking eye movement of a contact lens of claim 9, wherein the main control unit calculates the eye movement locus according to the acceleration data, the target angular velocity data and the geomagnetic data, and transmits the eye movement locus to the mobile terminal, further comprising: