Eyeblink detection device
A device disclosure includes a unit that measures an eye potential; and a unit that sets a threshold coefficient based on a frequency characteristic value of eye potential differential values and sets an upper threshold and a lower threshold based on a number obtained by multiplying a standard deviation of the eye potential differential values by the threshold coefficient, and detects a change in the eye potential differential values as the eyeblink waveform wherein the change occurs in the time-series data on the eye potential differential values either when the eye potential differential value becomes larger than the upper threshold and, after that, changes from the upper threshold to the lower threshold within a predetermined time or when the eye potential differential value becomes smaller than the lower threshold and, after that, changes from the lower threshold to the upper threshold within the predetermined time.
1. An eyeblink detection device comprising:
circuitry configured to:
generate time-series data on differential values of an eye potential of a subject;
determine a frequency characteristic value from the time-series data on the eye potential differential values, the frequency characteristic value representing a frequency characteristic of the eye potential differential values;
set a threshold coefficient based on the frequency characteristic value of the eye potential differential values;
set an upper threshold and a lower threshold based on a number obtained by multiplying a standard deviation of the differential values in the time-series data on the eye potential differential values by the threshold coefficient, the upper threshold and the lower threshold being used for detecting an eyeblink waveform in the time-series data on the eye potential differential values;
detect a change in the eye potential differential values as the eyeblink waveform, the change occurring in the time-series data either when the eye potential differential value becomes larger than the upper threshold and, after that, changes from the upper threshold to the lower threshold within a predetermined time or when the eye potential differential value becomes smaller than the lower threshold and, after that, changes from the lower threshold to the upper threshold within the predetermined time; and
output an eyeblink detection result based on the eyeblink waveform to a display.
2. The eyeblink detection device according to claim 1 , wherein
the frequency characteristic value is a value representing a ratio of a power of non-eyeblink waveform components to a power of an eyeblink waveform component in the time-series data on the eye potential differential values, and
the circuitry is configured to set the threshold coefficient larger when the frequency characteristic value is large than when the frequency characteristic value is small.
3. The eyeblink detection device according to claim 1 , wherein
the circuitry is configured to calculate a frequency spectrum of the time-series data on the eye potential differential values, and
the frequency characteristic value is a value representing a ratio of a power of non-eyeblink waveform components to a power of an eyeblink waveform component in the frequency spectrum of the eye potential differential values.
4. The eyeblink detection device according to claim 1 , wherein the frequency characteristic value is a ratio of a maximum value of a power of non-eyeblink waveform components to a power of an eyeblink waveform component and the threshold coefficient when the frequency characteristic value is large is set larger than when the frequency characteristic value is small.
5. The eyeblink detection device according to claim 1 , wherein the frequency characteristic value is a sum of powers of a frequency spectrum and the threshold coefficient when the frequency characteristic value is large is set larger than when the frequency characteristic value is small.
6. The eyeblink detection device according to claim 1 , wherein the subject is classified into one of groups based on the frequency characteristic value and the threshold coefficient is set for each of the groups into which the subject is classified.
7. The eyeblink detection device according to claim 1 , wherein an interval width of the time series data used for calculating the standard deviation of the differential values in the time-series data on the eye potential differential values is set based on the frequency characteristic value.
8. The eyeblink detection device according to claim 1 , wherein the circuitry is configured to detect an eyeblink time in the detected eyeblink waveform.
9. The eyeblink detection device according to claim 1 , wherein the circuitry includes a signal processing device.
10. The eyeblink detection device according to claim 9 , wherein the signal processing device includes a central processing unit and a storage device.
11. The eyeblink detection device according to claim 1 , further comprising a sensor configured to measure the eye potential of the subject.
12. The eyeblink detection device according to claim 11 , wherein the sensor includes an electrode configured to measure the eye potential of the subject.
13. The eyeblink detection device according to claim 11 , wherein the sensor includes a plurality of electrodes configured to measure the eye potential of the subject.
14. The eyeblink detection device according to claim 1 , further comprising the display.