WO2024048413A1 - Brain-wave measurement device - Google Patents

Abstract

This brain-wave measurement device comprises: a first detection electrode and a second detection electrode that detect brain waves as electric signals; and a body device that is connected to the first detection electrode and the second detection electrode via a first cable and a second cable, respectively. The body device comprises: a measurement unit which generates measurement data using the electric signals; and a communication control unit which wirelessly communicates a measurement result by using a prescribed connection interval frequency fci. The communication control unit sets the connection interval frequency fci equal to a commercial power supply frequency fac.

Description

EEG measuring device

The present invention relates to an electroencephalogram measuring device that transmits measurement results wirelessly.

Patent Document 1 describes a wearable electroencephalogram measuring device. The electroencephalogram measurement device of Patent Document 1 includes an electroencephalogram electrode, an electric wiring section, an electroencephalogram measurement module, and a communication module.

The electroencephalogram electrode inputs the detected electroencephalogram signal to the electroencephalogram measurement module through the electrical wiring section. The electroencephalogram measurement module measures electroencephalograms from electroencephalogram signals. The communication module transmits the brain wave measurement results to the outside.

JP2022-77070A

However, in the conventional electroencephalogram measuring device as shown in Patent Document 1, when the frequency of wireless communication (connection interval frequency) that performs intermittent communication overlaps with the frequency band of the electroencephalogram signal, noise affects the electroencephalogram measurement. I have something to give.

Therefore, an object of the present invention is to suppress the influence of intermittent wireless communication on brain wave measurement results.

An electroencephalogram measuring device according to an embodiment of the present invention includes a detection electrode that detects brain waves using electrical signals, and a main body device that is connected to the detection electrode by a cable. The main device includes a measurement unit that generates measurement data using electrical signals, and a communication control unit that wirelessly communicates measurement data at a predetermined connection interval frequency. Set the same as . In this configuration, noise generated in intermittent communication (connection interval frequency) is suppressed by the filter that suppresses noise at the frequency of the commercial power source included in the frequency band used for electroencephalogram measurement.

An electroencephalogram measuring device according to an embodiment of the present invention includes a detection electrode that detects brain waves using electrical signals, and a main body device that is connected to the detection electrode by a cable. The main device includes a measurement unit that generates measurement data using electrical signals, and a communication control unit that wirelessly communicates measurement data at a predetermined connection interval frequency. Set the connection interval frequency to a different frequency. With this configuration, even if noise from intermittent communication (connection interval frequency) occurs, the effect on brain wave measurement is small.

An electroencephalogram measuring device according to an embodiment of the present invention includes a detection electrode that detects brain waves using electrical signals, and a main body device that is connected to the detection electrode by a cable. The main device includes a measurement unit that generates measurement data using electrical signals, and a communication control unit that wirelessly communicates measurement data at a predetermined connection interval frequency. Set with . With this configuration, the accumulation of noise at connection interval frequencies due to multiple communications is suppressed, and the noise level at each connection interval frequency is suppressed.

An electroencephalogram measuring device according to an embodiment of the present invention includes a detection electrode that detects brain waves using electrical signals, and a main body device that is connected to the detection electrode by a cable. The main device includes a measurement unit that generates measurement data using electrical signals, and a communication control unit that wirelessly communicates measurement data at a predetermined connection interval frequency. Set higher than the off frequency. In this configuration, noise at the intermittent communication frequency (connection interval frequency) is suppressed by the filter.

According to any one of these inventions, it is possible to suppress the influence of intermittent wireless communication on brain wave measurement results.

FIG. 1 is a functional block diagram of an electroencephalogram measuring device according to a first embodiment. FIG. 2 is a time chart showing an example of a communication protocol executed by the electroencephalogram measuring device according to the first embodiment. FIG. 3(A) is a graph showing an example of the frequency characteristics of the input signal to the main device when using the electroencephalogram measuring device of the first embodiment, and FIG. 3(B) is a graph showing the input signal of the measuring section. 2 is a graph showing an example of a frequency spectrum of . FIG. 4 is a graph showing an example of the frequency characteristics of the input signal to the main device when the electroencephalogram measurement device of the second embodiment is used. FIG. 5 is a time chart showing an example of a communication protocol executed by the electroencephalogram measuring device according to the third embodiment. FIG. 6 is a graph showing an example of the frequency characteristics of the input signal to the main device when using the electroencephalogram measuring device of the third embodiment. FIG. 7 is a graph showing an example of the frequency characteristics of the input signal to the main device when using the electroencephalogram measuring device of the fourth embodiment.

[First embodiment]
An electroencephalogram measuring device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram of an electroencephalogram measuring device according to a first embodiment.

As shown in FIG. 1, the electroencephalogram measuring device 10 includes a first detection electrode 21, a second detection electrode 22, a first cable 31, a second cable 32, and a main unit 40. The main device 40 includes an AFE 41 , an ADC 42 , a measurement section 43 , a communication control section 44 , an antenna 45 , and a battery 49 .

(Configuration of electroencephalogram measuring device 10)
The main device 40 has a casing made of resin, metal, or the like. AFE 41, ADC 42, measurement section 43, communication control section 44, antenna 45, and battery 49 are housed in a housing. At this time, the antenna 45 is housed in the housing so that communication with the outside is possible. The casing is preferably of a size that allows it to be carried by the person whose brain waves are to be measured.

The AFE 41, ADC 42, measurement section 43, and communication control section 44 are realized by electronic components etc. mounted on a circuit board. That is, the AFE 41, ADC 42, measurement section 43, and communication control section 44 are realized by electronic circuits. The AFE 41, ADC 42, measurement section 43, and communication control section 44 are driven by receiving power from a battery 49.

The antenna 45 is a known antenna, and has a shape that can at least transmit radio waves with specifications (frequency, etc.) to be described later.

The battery 49 is a primary battery or a secondary battery, and may be detachable from the main device 40. Although it is possible to omit the battery 49 and replace it with a power supply unit connected to a commercial power source, the battery 49 is preferable. By using the battery 49, noise generated by the power supply unit can be prevented, and noise superimposed on electrical signals based on brain waves, which will be described later, can be suppressed.

The first detection electrode 21 is connected to the AFE 41 of the main device 40 through a first cable 31 . The second detection electrode 22 is connected to the AFE 41 of the main device 40 through a second linear cable 32 .

The first detection electrode 21 and the second detection electrode 22 are attached to the skin of the subject's head in order to measure brain waves. The first detection electrode 21 and the second detection electrode 22 detect brain waves as electrical signals and output them to the AFE 41 of the main device 40 through the first cable 31 . Note that the electrical signal is a signal that includes an electrical signal that reflects the brain waves of the subject and other electrical signals, and is an analog signal.

AFE41 is an analog front end circuit and includes an amplifier circuit and a filter. Note that the AFE 41 may include at least one of an amplifier circuit and a filter, but preferably includes both. AFE 41 amplifies and filters the electrical signal.

The filter is a low-pass filter, and suppresses noise that causes AD conversion errors in the subsequent ADC 42 and unnecessary high-frequency components during brain wave measurement. The cutoff frequency of the filter is set between the upper end frequency of the frequency band of the brain wave measurement range and the frequency of the high frequency component to be suppressed.

The AFE 41 outputs the electrical signal after amplification processing and filter processing (for example, low-pass filter processing, etc.) to the ADC 42.

The ADC 42 is an AD conversion circuit (analog-digital conversion circuit), converts an analog electrical signal into a digital signal, and outputs the digital signal to the measurement section 43.

The measurement unit 43 generates measurement data using electrical signals based on brain waves converted into digital signals (hereinafter referred to as "brain wave signals"). For example, the measurement unit 43 performs Fourier transform on the brain wave signal to generate a frequency spectrum of the brain wave signal. The measurement unit 43 measures the desired level (magnitude) of the brain wave from the frequency spectrum of the brain wave signal. The measurement unit 43 generates measurement data (measurement results) using the brain wave level.

For example, the measuring unit 43 measures the level of the δ wave from the spectrum intensity from 2 Hz to 4 Hz. The measurement unit 43 measures the level of the θ wave from the spectrum intensity from 4 Hz to 8 Hz. The measurement unit 43 measures the level of α waves from the spectrum intensity from 8 Hz to 13 Hz. The measurement unit 43 measures the level of β waves from the spectrum intensity from 13 Hz to 30 Hz. The measurement unit 43 measures the level of γ waves from the spectral intensity from 30 Hz to 300 Hz. The measurement unit 43 then generates measurement data using the levels of these various brain waves.

The measurement unit 43 outputs measurement data to the communication control unit 44.

The communication control unit 44 wirelessly communicates with an external device such as a PC through the antenna 45. At this time, the communication control unit 44 transmits the measurement data using a predetermined communication technology, such as Bluetooth (registered trademark) or BLE (Bluetooth Low Energy).

FIG. 2 is a time chart showing an example of a communication protocol executed by the electroencephalogram measuring device according to the first embodiment. Figure 2 shows only data channels.

When Bluetooth (registered trademark) shifts from the advertising channel to the data channel, the external device (master) transmits a packet to the electroencephalogram measuring device 10 (slave device) (Rx in FIG. 2), and the electroencephalogram measuring device 10 transmits a packet to the external device A reply packet (a packet indicating continuation of wireless communication) is transmitted to (Tx in FIG. 2). To reduce power consumption, this process (communication) is executed periodically (intermittently), and this cycle is the connection interval cycle Tci. Then, the connection interval frequency fci (=1/Tci) is determined by this connection interval period Tci.

In this way, the communication control unit 44 of the electroencephalogram measuring device 10 transmits measurement data using the predetermined connection interval frequency fci.

In such wireless communication, the frequency of intermittent communication (connection interval frequency) fci may be superimposed on the frequency spectrum component of the brain wave signal, which results in noise (noise due to intermittent communication).

In particular, as described above, when the first detection electrodes 21 and 22 are connected to the main device 40 through the linear first cables 31 and 32, the first cables 31 and 32 are antennas that receive noise due to intermittent communication. It functions as. As a result, noise due to intermittent communication is likely to be superimposed on the brain wave signal.

Here, if the first cables 31 and 32 are provided with a noise shield mechanism, the superposition of noise due to intermittent communication can be suppressed. However, when the first cables 31 and 32 are provided with a noise shielding mechanism, the first cables 31 and 32 are difficult to bend and become heavy, which may impair usability and lead to an increase in cost.

For this reason, it is preferable that the first cables 31 and 32 do not include a noise shielding mechanism. In this case, noise due to intermittent communication is likely to be superimposed on the electroencephalogram signal.

Since the first cable 31 and the second cable 32 are connected to the casing of the main device 40, the casing of the main device 40 and the first cable 31 and the second cable 32 are necessarily close to each other. Placed. Therefore, noise due to intermittent communication is likely to be superimposed on the electrical signals transmitted through the first cable 31 and the second cable 32.

(Specific processing of the electroencephalogram measuring device 10)
To solve this problem, the electroencephalogram measuring device 10 controls the connection interval frequency fci. FIG. 3(A) is a graph showing an example of the frequency characteristics of the input signal to the main device 40 when using the electroencephalogram measurement device of the first embodiment, and FIG. It is a graph showing an example of a frequency spectrum of a signal. Note that the frequency band ZF in FIGS. 3(A) and 3(B) is the frequency band of the brain wave measurement target.

The communication control unit 44 of the electroencephalogram measuring device 10 sets the connection interval frequency fci to be the same as the frequency fac of a commercial power source placed around the electroencephalogram measuring device 10 and used as a power source for electronic devices and the like. As a result, as shown in FIG. 3A, noise due to intermittent communication at the connection interval frequency fci overlaps with commercial power supply noise on the frequency axis.

The AFE 41 includes a commercial power supply noise suppression filter. Noise due to intermittent communication at the connection interval frequency fci and commercial power supply noise overlap on the frequency axis. Therefore, by matching the stopband of the suppression filter of the AFE 41 to the frequency of the commercial power supply noise, the suppression filter suppresses the commercial power supply noise as well as the noise due to intermittent communication at the connection interval frequency fci.

As a result, as shown in FIG. 3(B), in the input signal to the measurement unit 43, noise due to intermittent communication at the connection interval frequency fci is suppressed as well as commercial power supply noise.

Therefore, the measurement unit 43 can measure brain waves using the brain wave signal in which commercial power supply noise and noise due to intermittent communication at the connection interval frequency fci are suppressed. Thereby, the electroencephalogram measurement device 10 can suppress the influence of wireless communication on the electroencephalogram measurement results.

Note that when using the electroencephalogram measuring device 10 in a general environment (an environment that is different from an environment where there are no commercial power outlets, etc., or an environment where there is no other electronic equipment that uses commercial power), Power supply noise is unavoidable. Therefore, it is preferable that the electroencephalogram measurement device 10 includes a filter that suppresses commercial power supply noise.

For this reason, an electroencephalogram measuring device 10 designed to be used in a general environment is equipped with a commercial power supply noise suppression filter. As a result, the electroencephalogram measuring device 10 intended for use in a general environment can suppress noise at the connection interval frequency fci without the need to newly provide a filter for suppressing noise at the connection interval frequency fci.

In this embodiment, "the connection interval frequency fci is the same as the frequency fac of the commercial power supply" includes complete coincidence, and within the range where the noise due to intermittent communication of the connection interval frequency fci can be suppressed by the commercial power supply noise suppression filter. Including different ranges.

Further, in this embodiment, a mode has been shown in which the AFE 41 is provided with a commercial power supply noise suppression filter, but a commercial power supply noise suppression filter may be provided at a stage prior to the measurement of brain waves in the measurement unit 43.

[Second embodiment]
An electroencephalogram measuring device according to a second embodiment of the present invention will be described with reference to the drawings. The electroencephalogram measuring device according to the second embodiment differs from the electroencephalogram measuring device 10 according to the first embodiment in that the measurement unit 43 sets a frequency band used for measurement, and the communication control unit 44 sets a connection. Different interval frequencies. The other configurations of the electroencephalogram measuring device according to the second embodiment are the same as those of the electroencephalogram measuring device 10 according to the first embodiment, and a description of the similar parts will be omitted.

FIG. 4 is a graph showing an example of the frequency characteristics of the input signal to the main device 40 when the electroencephalogram measurement device of the second embodiment is used.

The measurement unit 43 sets a first frequency band ZF1 and a second frequency band ZF2 as frequency bands used for electroencephalogram measurement. The first frequency band ZF1 is set to a lower frequency band than the second frequency band ZF2. The upper end frequency f1u of the first frequency band ZF1 and the lower end frequency f2d of the second frequency band ZF2 are separated by a predetermined frequency.

The communication control unit 44 sets the connection interval frequency fci between the upper end frequency f1u of the first frequency band ZF1 and the lower end frequency f2d of the second frequency band ZF2. As a result, as shown in FIG. 4, noise due to intermittent communication at the connection interval frequency fci is not included in the first frequency band ZF1 and the second frequency band ZF2.

Therefore, the measurement unit 43 can measure brain waves excluding the portion of the brain wave signal that is affected by noise due to intermittent communication at the connection interval frequency fci. Thereby, the electroencephalogram measuring device can suppress the influence of wireless communication on the electroencephalogram measurement results.

At this time, the communication control unit 44 sets the upper end frequency f1u of the first frequency band ZF1 lower than 133 Hz, and sets the lower end frequency f2d of the second frequency band ZF2 higher than 133 Hz. Thereby, the connection interval frequency fci can be set to 133 Hz. Therefore, the electroencephalogram measuring device can suppress the influence of wireless communication on the electroencephalogram measurement results without changing the general Bluetooth (registered trademark) connection interval frequency.

[Third embodiment]
An electroencephalogram measuring device according to a third embodiment of the present invention will be described with reference to the drawings. The electroencephalogram measuring device according to the third embodiment differs from the electroencephalogram measuring device 10 according to the first embodiment in the connection interval frequency set by the communication control unit 44. The other configuration of the electroencephalogram measuring device according to the third embodiment is the same as that of the electroencephalogram measuring device 10 according to the first embodiment, and the explanation of the similar parts will be omitted.

FIG. 5 is a time chart showing an example of a communication protocol executed by the electroencephalogram measuring device according to the third embodiment. Figure 5 shows only data channels. FIG. 6 is a graph showing an example of the frequency characteristics of the input signal to the main device 40 when using the electroencephalogram measurement device of the third embodiment.

The communication control unit 44 sets the connection interval cycle to multiple types of cycles Tci1, Tci2, and Tci3. Note that although this embodiment has shown a mode in which the connection interval period is set to three types, the number of types is not limited to this.

Thereby, the communication control unit 44 performs wireless communication using multiple types of connection interval frequencies fci1, fci2, and fci3. As a specific example, in the case of FIG. 5, the communication control unit 44 performs wireless communication at the connection interval frequency fci2 in the next packet after the packet that wirelessly communicated at the connection interval frequency fci1. The communication control unit 44 performs wireless communication at the connection interval frequency fci3 in the next packet after the packet wirelessly communicated at the connection interval frequency fci2. The communication control unit 44 performs wireless communication at the connection interval frequency fci1 in the next packet after the packet wirelessly communicated at the connection interval frequency fci3. That is, the communication control unit 44 performs wireless communication while sequentially selecting and repeating a plurality of types of connection interval frequencies fci1, fci2, and fci3.

By performing such wireless communication, as shown in FIG. 6, the noise level (solid line in FIG. 6) due to intermittent communication at each of the connection interval frequencies fci1, fci2, and fci3 is reduced by using one type of connection interval frequency. The level of noise due to intermittent communication (dotted line in FIG. 6) is lower than that in the case of the above case.

Therefore, the influence of noise due to intermittent communication at the connection interval frequencies fci, fci2, and fci3 on the electroencephalogram signal input to the measurement unit 43 is reduced. Thereby, even if the connection interval frequencies fci, fci2, and fci3 are within the brain wave measurement frequency band ZF of the measurement unit 43, the electroencephalogram measuring device can suppress the influence of wireless communication on the brain wave measurement results.

Note that the settings of the plurality of types of connection interval frequencies fci1, fci2, and fci3 are preferably in a predetermined order that is shared between the electroencephalogram measurement device and the external device. However, it may be random as long as the electroencephalogram measurement device and the external device perform processing that allows the next connection interval frequency to be shared (for example, the packet currently being transmitted includes information about the next connection interval frequency).

[Fourth embodiment]
An electroencephalogram measuring device according to a fourth embodiment of the present invention will be described with reference to the drawings. The electroencephalogram measuring device according to the fourth embodiment differs from the electroencephalogram measuring device 10 according to the first embodiment in the connection interval frequency set by the communication control unit 44. The other configuration of the electroencephalogram measuring device according to the fourth embodiment is the same as that of the electroencephalogram measuring device 10 according to the first embodiment, and the explanation of the similar parts will be omitted.

FIG. 7 is a graph showing an example of the frequency characteristics of the input signal to the main device 40 when the electroencephalogram measurement device of the fourth embodiment is used.

The communication control unit 44 sets the connection interval frequency fci higher than the upper end frequency fcf of the electroencephalogram measurement frequency band ZF of the measurement unit 43. As a result, as shown in FIG. 7, noise caused by intermittent communication at the connection interval frequency fci does not fall into the brain wave measurement frequency band ZF. Thereby, the electroencephalogram measuring device can suppress the influence of wireless communication on the electroencephalogram measurement results.

10: EEG measuring device 21: First detection electrode 22: Second detection electrode 31: First cable 32: Second cable 40: Main unit 41: AFE
42: ADC
43: Measuring unit 44: Communication control unit 45: Antenna 49: Battery

Claims (5)

a detection electrode that detects brain waves using electrical signals;
A main unit connected to the detection electrode by a cable,
The main body device is
a measurement unit that generates measurement data using the electrical signal;
a communication control unit that wirelessly communicates the measurement data at a predetermined connection interval frequency;
Equipped with
The communication control unit sets the connection interval frequency to be the same as a frequency of a commercial power source.
EEG measuring device. a detection electrode that detects brain waves using electrical signals;
a main unit connected to the detection electrode by a cable;
Equipped with
The main body device is
a measurement unit that generates measurement data using the electrical signal;
a communication control unit that wirelessly communicates the measurement data at a predetermined connection interval frequency;
Equipped with
The communication control unit sets the connection interval frequency to a frequency different from a frequency used for measuring the brain waves.
EEG measuring device. a detection electrode that detects brain waves using electrical signals;
a main unit connected to the detection electrode by a cable;
Equipped with
The main body device is
a measurement unit that generates measurement data using the electrical signal;
a communication control unit that wirelessly communicates the measurement data at a predetermined connection interval frequency;
Equipped with
The communication control unit sets the connection interval frequency at a plurality of frequencies.
EEG measuring device. The communication control unit includes:
setting the connection interval frequency so that the same frequency does not continue;
The electroencephalogram measuring device according to claim 3. a detection electrode that detects brain waves using electrical signals;
a main unit connected to the detection electrode by a cable;
Equipped with
The main body device is
a filter that performs low-pass filter processing on the electrical signal;
a measurement unit that generates measurement data using the electrical signal;
a communication control unit that wirelessly communicates the measurement data at a predetermined connection interval frequency;
Equipped with
The communication control unit sets the connection interval frequency higher than a cutoff frequency of the filter.
EEG measuring device.

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