JP2005205024A - Method and apparatus for eye movement measurement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure eye movement by illuminating a light on an eyelid with the eye closed and detecting the reflected light. <P>SOLUTION: A light in the near infrared range is illuminated on the eyelid of the subject by a light emitting diode 3, and the intensity of the reflected light is measured by a photodiode 4 to measure the eye movement of the subject. Compared with a conventional electrooculogram, this method is simply handled, has superior detection sensitivity and scarcely receives the effect of noise such as myogenic potential. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an eye movement measurement method and a measurement apparatus capable of measuring eye movement from above the eyelid when a subject sleeps.

It is known that when the electroencephalogram shows an awake state during sleep, the eyeball moves rapidly. This state is called REM (Rapid Eye Movement) sleep. Therefore, by measuring the eye movement during sleep, the type of sleep can be determined, so that it can be applied to diagnosis of biological rhythm and diagnosis of sleep rhythm.
As a conventional sleep state detection method, a method of detecting a potential difference by applying electrodes to the left and right temples by utilizing the fact that the cornea of the eyeball is positively charged and the retina is negatively charged is known. Thereby, the movement of the eyeball in the left-right direction can be detected. In addition, by detecting the potential difference by attaching electrodes to the upper and lower sides of the eyelid, the vertical movement of the eyeball can be detected. These records are called electrooculograms.
JP-A-9-635

However, in the conventional method, it is necessary to attach a large number of electric wires to the human body. It is necessary to attach the ground wire to the ear.
Further, in order to maintain good sensitivity, it is necessary to perform measurement by reducing the impedance of the electrode with the skin to 5 kΩ or less. Therefore, it is necessary to disinfect the skin with alcohol or to apply a surface treatment agent, and the subject feels uncomfortable and the skin becomes rough.

Further, in this method, the myoelectric potential and brain waves of the face are mixed in the voltage signal, so that noise is likely to occur and it is difficult to distinguish from the ocular potential and myoelectric potential.
Therefore, an object of the present invention is to provide an eye movement measurement method that can accurately measure the movement of the eyeball with good sensitivity.
Furthermore, an object of the present invention is to provide an eye movement measuring apparatus that can implement the eye movement measuring method with a simple apparatus configuration.

The present inventor has found a method for measuring eye movement by shining light on the eyelid with the eyes closed and detecting the reflected light. According to this method, it was confirmed that subtle fluctuations in the eyeball can be detected with less noise and better detection sensitivity than the electrooculogram.
The eye movement measurement method of the present invention is characterized in that the eye movement of the subject is measured by irradiating the subject's eye with light in the near-infrared region by the light emitting element and measuring the reflected light intensity by the light receiving element. To do.

According to this method, since the movement of the eyeball through the eyelid is measured using near-infrared light, measurement can be performed with good sensitivity without being affected by myoelectric potential. Further, by using near infrared light that is not recognized by the eye, measurement can be performed without disturbing sleep.
Specifically, the wavelength of light in the near-infrared region is preferably in the range of 800 nm to 1000 nm.

  It is desirable that the distance between the light emitting element and the ridge and the distance between the light receiving element and the ridge be measured at 2 mm or more and 15 mm or less, respectively. The measurement is possible even in a state of less than 2 mm, that is, almost in contact with the eyelid, but it is not so preferable because it prevents the eyelid from moving by preventing the eyelid from opening or pressing the eyelid. If the distance is further than 15 mm, the height of the light emitting element and the light receiving element becomes too high, which hinders handling.

  The eye movement measuring device of the present invention includes a light emitting element that irradiates a subject's eyelid with light in the near-infrared region, a light receiving element that measures the intensity of reflected light from the eyelid, and a driving unit that drives the light emitting element. Observation means for observing the waveform of the output signal detected by the light receiving element. With this device, the movement of the eyeball from the skin surface of the eyelid can be accurately measured with good sensitivity using near infrared light. Moreover, since it only needs to be mounted on the bag, the device is easy to handle.

In order to separate the light emitting element and the light receiving element from the heel by a predetermined distance, it is preferable to include a plate on which the light emitting element and the light receiving element are attached and a mounting member for mounting the plate on the face at a distance from the heel. . The subject can easily perform the measurement simply by mounting the mounting member to which the plate is attached on the bag.
The mounting member is preferably made of a soft material that fits the face, such as rubber, sponge, or cloth.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a sensor 1 constituting the eye movement measurement apparatus during sleep according to the present invention and its electrical connection state.
FIG. 1A shows a front view of the sensor 1, and FIG. 1B shows a side view of the sensor 1 and an electrical connection state.

This sensor 1 has a light emitting element 3 and a light receiving element 4 attached to one side of a plate 2.
Although the material of the board 2 is not ask | required, an acrylic board can be used, for example. The shape is, for example, a circle or an ellipse having a diameter of about 20 mm.
The light emitting element 3 may be of any type as long as it emits light having a predetermined wavelength. A light emitting diode (LED), an incandescent bulb, a cold cathode ray tube, or the like can be used. In particular, a light-emitting diode that is small and inexpensive and has low power consumption is preferable. The wavelength of light is preferably in a wavelength region that is not harmful to the human body such as ultraviolet rays, has no heating effect, and is not visible. In particular, light in the near infrared region of 800 nm to 1000 nm is preferable. If it is less than 800 nm, it is visible and disturbs sleep. If it is longer than 1000 nm, it is in the infrared region, has a heating effect, and disturbs sleep.

The light receiving element 4 may be an element having sensitivity in a light region emitted from the light emitting element 3. For example, a phototransistor can be used.
The arrangement interval between the light emitting element 3 and the light receiving element 4 is preferably about 15 mm, but measurement is possible even closer to it. If it is more than 15mm, it will be too big and it will not fit in the bag, so it cannot be measured.

The light emitting element 3 and the light receiving element 4 are connected to a driver 5 and a detector 6 by thin electric wires 7, respectively. The driver 5 is a drive circuit that supplies a necessary current to the light emitting element 3, and the detector 6 is a circuit that applies a bias voltage to the light receiving element 4 to detect, amplify, and filter the current flowing through the light receiving element 4.
FIG. 2 shows a specific circuit diagram of the driver 5 and the detector 6. The driver 5 is a circuit that causes a drive current to flow to the light emitting element 3 through a 100Ω fixed resistor and a 1 kΩ variable resistor. The detector 6 receives a current flowing through a phototransistor, which is a light receiving element, with a resistor R of 100 kΩ. The signal appearing in the resistor R is supplied to the operational amplifier through a high-pass filter (cutoff frequency: 1 Hz) composed of a capacitor and a resistor. The operational amplifier performs voltage amplification at a set magnification and outputs it as a voltage signal. The time waveform of this voltage signal is observed by a waveform observer 8 such as a synchroscope.

  FIG. 3 is a perspective view (a) and a cross-sectional view (b) showing a state where a cylindrical tube 9 as a mounting member is attached to the sensor 1. The cylinder 9 is used to keep the distance between the light emitting element 3 and the light receiving element 4 of the sensor 1 and the bag constant. The tube 9 is wound around the outer periphery of the plate 2 and bonded. The material of the tube 9 is not particularly limited, such as rubber, sponge, cloth, resin, paper, etc., but it is preferable that the tube 9 has a hardness that does not hurt when touching the heel and is easy to fit, such as rubber or sponge.

  The distance between the light emitting element 3 and the light receiving element 4 of the sensor 1 and the ridge is preferably 2 mm or more and 15 mm or less. If it is less than 2 mm, it is not so preferable because it prevents the eyelids from opening or presses against the eyelids to prevent the movement of the eyeball. If the distance is further than 15 mm, the sensor 1 is too high when the sensor 1 is attached to the bag, which makes the handling inconvenient and disturbs sleep.

  FIG. 4 is a perspective view showing a method of attaching the sensor 1 to the eye mask 10. The part of the eye mask 10 where both eyes hit is opened, and the sensor 1 is adhered from the outside. Thereby, the movement of the eyeball of both eyes can be measured, respectively. However, it is not absolutely necessary to attach the sensor 1 to both eyes, and it may be attached to at least one eye. In this way, the movement of the eyeball of the eye to which the sensor 1 is attached can be measured.

FIG. 5 is a side view showing a state in which the subject wears the eye mask 10. In this state, the light detection waveform of the light receiving element 4 is observed.
As described above, according to the embodiment of the present invention, it is possible to measure the eye movement simply by attaching the eye mask 10 to the face. The trouble of attaching a plurality of electrodes to the face is reduced, and there is no need to clean the skin.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments. For example, in addition to attaching the sensor 1 to the eye mask, the sensor 1 may be directly attached to the face with a plaster or the like, or the sensor 1 is attached to a hole of a rubber-like mounting member having a hole like underwater glasses. May be. In the case of relaxation such as massage, you can simply attach it to the eye pillow and place it on the heel. In addition, various modifications can be made within the scope of the present invention.

<Example 1>
The light emitting element and the light receiving element were fixed to an acrylic disc having a diameter of 20 mm and a thickness of 2 mm with an adhesive. These intervals are 14 mm. The light emitting element and the light receiving element were attached to one side of the eye mask so that they were aligned vertically.
A light emitting diode TLN110 manufactured by Toshiba Corporation was used as the light emitting element. The peak of the emission wavelength is around 900 nm in the near infrared region. As the light receiving element, a phototransistor TPS611 manufactured by Toshiba Corporation was used. It has sensitivity near 900 nm in the near infrared region. A natural rubber sheet having a thickness of 2 mm and a height of 2 mm was attached around the acrylic disk to form a cylindrical shape. As a result, the distance between the element and the flange became 2 mm.

The eye mask was attached to the subject, and the eyeball was moved left and right and up and down to observe the output voltage signal waveform of the light receiving element.
<Example 2>
A sensor having the same structure as in Example 1 was prepared except that the height of the natural rubber sheet was 10 mm. The distance between the element and the ridge was 10 mm.

The eye mask was attached to the subject, and the eyeball was moved left and right and up and down to observe the output voltage signal waveform of the light receiving element.
<Example 3>
A sensor having the same structure as in Example 1 was prepared except that the height of the natural rubber sheet was 15 mm. The distance between the element and the ridge was 15 mm.

The eye mask was attached to the subject, and the eyeball was moved left and right and up and down to observe the output voltage signal waveform of the light receiving element.
<Comparative example>
Measurement was performed using an amplifier “ECG” manufactured by NEC Sanei Co., Ltd. For the electrooculogram measurement, one silver-silver chloride electrode “SEE105” manufactured by GE Marquette Medical System Co., Ltd. is attached to the left orbital outer edge, one right orbital outer edge, and one left lower orbital upper edge. At the same time, a reference (ground) electrode was attached to one ear. The voltage was measured by moving the eyeball left and right and up and down.

<Evaluation method>
The output voltage signal of the light receiving element and the measurement voltage signal of the electrooculogram were measured by a data collection device manufactured by NEC Sanei Co., Ltd. The measurement data was transmitted and received using a telemeter “TRANSMITTER san-ei V1, RECEIVER BAND V1”.
<Result>
In FIG. 6, the measurement result when moving the eye of Example 1 right and left and the measurement result of a comparative example are shown. (A) is a graph of an output voltage signal waveform when the eye of Example 1 is moved to the left and right, and (b) is a voltage signal of an electrode attached to the outer edge of the eye socket when the eye of the comparative example is moved to the left and right. It is a graph.

FIG. 7 shows a measurement result when the eye of Example 1 is moved up and down and a measurement result of the comparative example. (A) is a graph of an output voltage signal waveform when the eye of Example 1 is moved up and down, and (b) is a voltage signal of electrodes attached to the upper and lower edges of the orbit when the eye of the comparative example is moved up and down. It is a graph of.
FIG. 8 shows a measurement result when the eye of Example 2 is moved left and right and a measurement result of the comparative example. (A) is a graph of an output voltage signal waveform when the eye of Example 2 is moved to the left and right, and (b) is a voltage signal of an electrode attached to the outer edge of the eye socket when the eye of the comparative example is moved to the left and right. It is a graph.

FIG. 9 shows a measurement result when the eye of Example 2 is moved up and down and a measurement result of the comparative example. (A) is a graph of an output voltage signal waveform when the eye of Example 2 is moved up and down, and (b) is a voltage signal of electrodes attached to the upper and lower edges of the orbit when the eye of the comparative example is moved up and down. It is a graph of.
FIG. 10 shows a measurement result when the eye of Example 3 is moved to the left and right and a measurement result of the comparative example. (A) is a graph of an output voltage signal waveform when the eye of Example 3 is moved to the left and right, and (b) is a voltage signal of an electrode attached to the outer edge of the eye socket when the eye of the comparative example is moved to the left and right. It is a graph.

FIG. 11 shows the measurement results when the eye of Example 3 is moved up and down and the measurement results of the comparative example. (A) is a graph of an output voltage signal waveform when the eye of Example 3 is moved up and down, and (b) is a voltage signal of electrodes attached to the upper and lower edges of the orbit when the eye of the comparative example is moved up and down. It is a graph of.
It can be seen that the voltage waveforms of Examples 1 to 3 have less noise and better sensitivity than the voltage waveforms of the comparative examples, both when the eyeball is moved left and right and when it is moved up and down.

  As can be seen from FIGS. 6 to 11, according to the present invention, the movement of the eyeball can be captured with better sensitivity than in the past. In addition, since there is almost no change in muscle potential due to the movement of the eyeball, it is possible to directly observe the movement of the eyeball during sleep with little noise. Furthermore, it is possible to detect the movement of the upper, lower, left, and right eyes with one sensor, and the configuration of the measuring apparatus is simplified.

It is a schematic diagram which shows the sensor 1 (a) which comprises the eye movement measurement apparatus at the time of sleep of this invention, and its electrical connection state (b). 3 is a specific circuit diagram of a driver 5 and a detector 6. FIG. They are a perspective view (a) and a sectional view (b) showing a state where a cylindrical tube 9 is attached to the sensor 1. 2 is a perspective view showing a method for attaching the sensor 1 to the eye mask 10. FIG. 1 is a side view showing a state in which a subject wears this eye mask 10. FIG. It is a graph of the voltage signal which appeared in the measurement result when moving the eyes of Example 1 right and left, and the measurement result of a comparative example. It is the graph of the voltage signal which appeared in the measurement result when moving the eyes of Example 1 up and down, and the measurement result of a comparative example. It is a graph of the voltage signal which appeared in the measurement result when moving the eyes of Example 2 right and left, and the measurement result of a comparative example. It is a graph of the voltage signal which appeared in the measurement result when moving the eyes of Example 2 up and down, and the measurement result of the comparative example. It is a graph of the voltage signal which appeared in the measurement result when moving the eyes of Example 3 right and left, and the measurement result of a comparative example. It is a graph of the voltage signal which appeared in the measurement result when moving the eyes of Example 3 up and down, and the measurement result of the comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor 2 Plate 3 Light emitting element 4 Light receiving element 5 Driver 6 Detector 7 Electric wire 8 Waveform observer 9 Tube 10 Eye mask 11 瞼

Claims (8)

  A method for measuring eye movement, comprising: irradiating a subject's eye with light in the near-infrared region with a light emitting element, and measuring the eye movement of the subject by measuring the intensity of reflected light with a light receiving element.   The method for measuring eye movement according to claim 1, wherein the wavelength of light in the near infrared region is in the range of 800 nm to 1000 nm.   The eye movement measurement method according to claim 1, wherein the measurement is performed while keeping the distance between the light emitting element and the eyelid and the distance between the light receiving element and the eyelid at 2 mm or more and 15 mm or less, respectively.   A light emitting element that irradiates a subject's eyelid with light in the near infrared region, a light receiving element that measures the intensity of reflected light from the eyelid, driving means that drives the light emitting element, and an output signal detected by the light receiving element An eye movement measuring device comprising observation means for observing a waveform.   The eye movement measurement device according to claim 4, wherein the wavelength of the light emitting element is in a range of 800 nm to 1000 nm.   The eye movement measurement device according to claim 4, comprising: a plate on which the light emitting element and the light receiving element are attached; and an attachment member for attaching the plate to the face at a distance from the eyelid.   The eye movement measuring device according to claim 6, wherein a distance between the plate and the eyelid is 2 mm or more and 15 mm or less.   The eye movement measuring device according to claim 6, wherein a material of the mounting member is rubber.

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