JPH0779936A - Device for preventing driver from dozing off - Google Patents

Abstract

PURPOSE:To prevent a driver from dozing off by issuing an alarm when the state of half-awakening is detected through the quantitative analysis of bionic signal input from clips attached to both ears. CONSTITUTION:The device comprises two clips 1 and 2 to which electrodes 1 through 3 generating bionic signals are attached, a differential amplifier a3 to amplify boinic signal input, a filter 3 through which brain waves and electromyogram(EMG) signals are sorted out, a bionic signal processing unit 4 into which the brain waves and EMG signals are input to obtain the amplitude values of both the alpha-wave band of the brain waves and EMG signals, an evaluation unit 5 in which the ratio of the alpha-wave amplitude value to the EMG signal amplitude value is obtained in the case of full awakening and half-awakening respectively and then the ratio at the time of half-awakening is divided by the ratio at the time of full awakening to obtain an identifying value in order to compute the logarithm of the identifying value to be compared with the specified value so that an alarm signal is output when the logarithm value exceeds the specified value, and an alarm unit 6 to set off an alarm in response to the alarm signal output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drowsiness prevention device for detecting and preventing drowsiness that occurs during driving of an automobile, for example.

[0002]

2. Description of the Related Art Conventionally, for the purpose of preventing drowsiness while driving a vehicle, there is known a method of detecting brain waves and detecting changes in alpha (α) waves from awakening to falling asleep to detect drowsiness. In this method, the head hair of the driver is divided and a plurality of brain wave electrodes are attached on the scalp to extract the brain waves. However, such a method has been researched and requires prior knowledge of a correct electrode mounting method, and is not yet in the practical stage where it can be actually used.

Further, there is also known a device in which the movement of the eyes stops at the time of falling asleep, and this is detected by a photodetector or an electrode attached near the eyes to generate an alarm sound or the like.

[0004]

However, it is technically difficult for a general driver to mount the electrode by the above-mentioned conventional method before starting the driving. Further, when such an electrode is attached to the head, the driver feels uncomfortable and feels restricted by the lead wire, which imposes a burden.

Further, the determination is not sufficient because changes in α-waves in the electroencephalogram or stop of eye movement are simply used qualitatively.

Therefore, an object of the present invention is to provide a drowsiness prevention device having a simple structure and easy to wear.

[0007]

As shown in FIG. 1, for example, a drowsiness prevention device of the present invention includes two clips 1 and 2 attached to both ears and having electrodes E1 to E3 for deriving a biological signal, and a living body. A differential amplifier a3 for inputting and amplifying a signal
And a filter 3 for extracting an electroencephalogram and an electromyogram signal from the biosignal, and an electroencephalogram and an electromyogram signal as input to obtain an amplitude value of an alpha wave band included in the electroencephalogram and an amplitude value of the electromyogram signal. The signal processing means 4 and the ratio of the amplitude value of the alpha wave band to the amplitude value of the EMG signal are obtained for each of awakening and half awakening, and the half awakening ratio is divided by the awakening ratio to obtain an identification value. In addition to the determination, the logarithm of the identification value is calculated and compared with a predetermined value, and the determination means 5 outputs an alarm signal when the value is equal to or larger than the predetermined value, and the alarm means 6 generates an alarm in response to the alarm signal. It is a thing.

[0008]

[Operation] Clips 1 and 2 with electrodes attached to the left and right ears
Is attached to detect a biological signal, and the detected biological signal is separated by the filter 3 into an electroencephalogram signal and an electromyogram signal. Frequency analysis is performed by the biomedical signal processing unit 4, and from the electroencephalogram to the alpha wave (α
The amplitude value of the (wave) band is obtained and the amplitude value of the EMG signal is obtained. Next, the determination unit 5 obtains the ratio of the amplitude value of the α-wave band to the amplitude value of the EMG signal for each of awakening and half awakening, and further divides the half awakening ratio by the awakening ratio. An identification value is obtained, and when the identification value is equal to or larger than a predetermined value, an alarm signal is generated and the alarm unit 6 issues an alarm. Therefore, by using a simple structure in which the earlobe is sandwiched by the clip, it is easy to wear and the feeling of discomfort and restraint of the driver is reduced,
A biological signal can be input for a long time, a half awake state can be detected, and drowsiness can be prevented.

[0009]

The present invention shows that during half awakening from awakening to falling asleep, increase of burst wave in alpha wave band included in brain wave (hereinafter referred to as EEG) and decrease of electromyographic signal (hereinafter referred to as EMG). Focusing on what can be seen, by quantitatively analyzing these, it is possible to detect changes in the awakening level and issue an alarm to prevent drowsiness.

In the electroencephalogram measurement, both ears are generally used as indifferent electrodes, but the earlobe has a considerably large electroencephalographic activity due to ripples from the parietal region, the temporal region and the occipital region, which is problematic as a reference electrode. However, since earlobe is less likely to be mixed with body movement noise, the present invention conversely utilizes this electroencephalogram activity.

An embodiment of the drowsiness prevention device of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. 1 and 2
Is a clip made of an elastic material such as plastic that is attached to the left and right earlobes of the living body M. The left ear clip 1 is composed of a clip body 1a, electrodes E1 and E2 attached near the tip of the clip body 1a, and an impedance converter a1 (described later) connected to the electrode E1. Similarly, the clip 2 for the right ear is composed of a clip body 2a, an electrode E3 attached near the tip thereof, and an impedance converter a2.

2 and 3 are perspective views showing a detailed structure of the left and right ear clips. FIG. 2 shows a clip 1 for the left ear, in which electrodes E1 and E2 (wavy line portions) are attached to the inside of both pieces at the tip, and an impedance converter a1 connected to the electrode E1 is attached to the upper surface of one piece with an adhesive. Etc., and is pulled out to the outside through the lead wire L1. Further, the electrode E2 is led to the outside via the lead wire L2.

The right ear clip 2 has the same structure as the left ear clip 1, but only the electrode E3 is attached to the inside of one piece of the tip portion. The impedance converter a2 is connected to the electrode E3, and is led out to the outside via the lead wire L3.

Of the left and right clips 1 and 2 above,
The electrodes E1 to E3, the impedance converters a1 and a2, and the lead wires L1, L2, and L3 may be embedded in advance during clip molding.

In FIG. 1, the above-mentioned impedance converters a1 and a2 are composed of, for example, a differential amplifier or the like, and reduce the biological signal detected from the electrode E1 of the left ear clip 1 and the electrode E3 of the right ear clip. Output with impedance. The electrode E1 of the left ear clip 1 is connected to the non-inverting input terminal of the impedance converter a1, and the electrode E3 of the right ear clip 2 is connected to the non-inverting input terminal of the impedance converter a2. The inverting input terminals of both impedance converters a1 and a2 are connected to their respective output terminals. By using the impedance converter, the influence of external noise can be reduced even if the lead wires L1 and L3 connected to the electrodes E1 and E3 become long.

Reference numeral a3 is a differential amplifier which amplifies the biological signals detected by the left and right earlobes output from the impedance converters a1 and a2 by inputting them to the non-inverting input terminal and the inverting input terminal, respectively. The electrode E2 of the left ear clip 1 is connected to the common (ground) terminal as body ground. That is, in the electroencephalogram, the electrode E2 of the left ear clip 1 is the indifferent electrode (the electrode attached to the portion where the potential change is small), and the electrode E1 of the left ear clip 1 and the right ear clip E3 are the related electrodes ( It is taken out by bipolar derivation (deriving method for obtaining a difference in potential change between electrodes), which is an electrode attached to a part for deriving a biological signal.

Reference numeral 3 denotes a filter circuit having two filters, which inputs the biomedical signal output from the differential amplifier a3 and separates and outputs EEG and EMG having different frequency bands.

4 is, for example, a fast Fourier transform circuit (FF
In the biological signal processing unit consisting of T), EEG and EMG separated by the filter 3 are input as parameters, and E
Determine the amplitude values of EG and EMG. That is, the amplitude value of the alpha wave band of the frequency band of 7.8 Hz to 13.2 Hz is extracted from the EEG, and the E of the frequency band of 61 Hz to 125 Hz is extracted.
The MG amplitude value is extracted.

Reference numeral 5 denotes a determination unit, which inputs the α-wave band amplitude value and the EMG amplitude value output from the biological signal processing unit 4,
The ratio of the amplitude value of the α-wave band to the amplitude value of EMG is calculated for each of awakening and half awakening. Further, from the ratio of the amplitude value of the α-wave band at the time of awakening / the amplitude value of EMG = A and the amplitude value of the α-wave band at the time of half awakening / the amplitude value of EMG = D value, DT
(Identification value) = D / A is calculated. Further, the determination unit 5 calculates 20LogDT based on the calculated DT value,
A DT value that satisfies 0LogDT> 0 dB is determined to be a half-awakening state, and an alarm signal is output.

Reference numeral 6 denotes an alarm generation unit, which is composed of, for example, a buzzer or a small speaker, and generates an alarm sound according to an alarm signal output from the determination unit 5. Further, the alarm generation unit 6 may not only generate an alarm based only on sound, but may also use a lamp or the like to generate an alarm signal by blinking light, for example.

In the above structure, the left and right clips 1 and 2 are attached to the left and right earlobes, respectively, and the electrodes E1 to E3 are connected to the impedance converters a1 and a2 and the differential amplifier a.
A biometric signal is input via 3. The biological signal amplified by the differential amplifier a3 is EEG by the filter circuit 3.
And EMG are separated and output to the biological signal processing unit 4.

The biological signal processing section 4 performs frequency analysis of the input EEG and EMG to obtain the amplitude value of the α wave band of the frequency band 7.8 Hz to 13.2 Hz included in the EEG, and the frequency band 61 Hz to. 125Hz EMG
Find the amplitude value of.

The α-wave band amplitude value and the EMG amplitude value are output to the determination unit 5, and the ratio of the α-wave band amplitude value to the EMG amplitude value is calculated for each of awakening and semi-wakefulness. From the ratio (= A) of the amplitude value of the α-wave band to the amplitude value of the EMG and the ratio (= D) of the amplitude value of the α-wave band to the amplitude value of EMG during half awakening, the discrimination value DT = D / A Is calculated. 20LogDT is calculated based on this DT value, and if this value is> 0, an alarm signal is output assuming that the user is in the half awake state.

[0024]

[Table 1]

Table 1 shows the results of detecting half-awakening state according to the present invention with respect to six subjects simulating drowsiness during driving. As is apparent from the table, the amplitude values in the α-wave band of the four subjects excluding the subjects 1 and 5 increased more in the method of half awakening than in awakening. Further, it can be seen that the amplitude values of EMG are decreased in the half awakening than in the awakening in five persons except the subject 3. However, only the changes in the amplitude value of the α-wave band and the amplitude value of the EMG are unlikely to be parameters for doze detection from the results of the subjects 1, 3 and 5. Therefore, in the present invention, as described above, the amplitude value of the α wave band and the EM
Regarding the ratio of G amplitude values (α / EMG), the ratio (D / A value) of semi-awakening / wakefulness was determined as a parameter. By doing so, the D / A value at half awakening and at awakening in each subject becomes twice or more, and detection can be performed.

When the determination unit 5 determines that the user is in the half-awakening state, an alarm signal is output to the alarm generation unit 6,
A warning sound is emitted to the driver.

As described above, according to the present invention, the left and right earlobe are sandwiched by the clip provided with the electrodes, and the appearance of the α burst wave at the time of awakening and the constant EMG signal are confirmed from the EEG and EMG signals derived from the clip. By quantitatively analyzing the decrease with respect to the level, it is possible to detect a half awake state (drowsy state) and issue an alarm.

In the above structure, a micro transmitter and a battery for weak radio waves are embedded in the left and right ear clips,
It is also possible to transmit a radio wave in which a biomedical signal is modulated and to provide a demodulator in front of the differential amplifier a3 on the main body side to demodulate and take out the biomedical signal. This eliminates the lead wire connected to the main body side of the clip, so that the driver's feeling of restraint can be eliminated.

Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0030]

As described above, according to the present invention, since the biological signal can be derived from the electrodes of the clip which can be worn on both ears, the wearing is extremely easy and the number of lead wires is small, so that the subject can be examined. The feeling of restraint can be reduced.

Further, as compared with the conventional qualitative detection based on increase / decrease of a single biomedical signal, the semi-awakening state is quantitatively detected from the electroencephalogram and the electromyogram signal, so that high detection accuracy can be obtained. There is an advantage.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a drowsiness prevention device of the present invention.

FIG. 2 is a perspective view showing a configuration of a left ear clip used in the embodiment of FIG.

FIG. 3 is a perspective view showing a configuration of a right ear clip used in the embodiment of FIG.

[Explanation of symbols]

 1, 2 Left and right clip 3 Filter circuit 4 Biological signal processing unit 5 Judgment unit 6 Alarm generation unit E1 to E3 electrodes a3 Differential amplifier

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location A61M 21/02 7638-4C A61B 5/04 330 A61M 21/00 330 A

Claims (1)

[Claims] 1. A clip mounted on both ears and having electrodes for deriving a biological signal, a differential amplifier for inputting and amplifying the biological signal, and an electroencephalogram and an electromyogram signal extracted from the biological signal. A filter, the EEG and EMG signals are input, the biological signal processing means for obtaining the amplitude value of the alpha wave band included in the EEG and the amplitude value of the EMG signal, and the EMG signal The ratio of the amplitude value of the alpha wave band to the amplitude value is obtained for each of awakening and semi-wakefulness, and the identification value is obtained by dividing the ratio of the half-wakefulness by the ratio of the awakening, and the identification value The doze prevention is characterized by comprising a determination means for calculating the logarithm of the above and comparing it with a predetermined value and outputting an alarm signal when the predetermined value or more, and an alarm means for issuing an alarm in response to the alarm signal. apparatus.