Biological signal processing system

• US 5,263,487 A
• Filed: 11/19/1991
• Issued: 11/23/1993
• Est. Priority Date: 11/20/1990
• Status: Expired due to Fees

• Current Assignee: GEZ Corporation, Sagami Tsushin Kogyo Limited
• Original Assignee: Hirotoki Kawasaki
• Inventors: Sakamoto, George, Kawasaki, Hirotoki
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US07/794,526
• Time in Patent Office: 735 Days
• Field of Search: 128/731-732, 128/905
• US Class Current: 600/544
• CPC Class Codes: A61B 5/2415 Measuring direct current [DC] or slowly varying biopotentials
• CPC Class Codes: A61B 5/374 Detecting the frequency distribution of signals, e.g. detecting delta, theta, alpha, beta or gamma waves
• CPC Class Codes: A61B 5/375 using biofeedback

Abstract

A biological signal processing system for extracting differential signals for alternating signals detected by at least two sensors, and analyzing and processing a plurality of frequency components contained in the differential signals within a predetermined time span, in which a low-pass filter to which the alternating signals are inputted, and a high-pass filter to which the output of the low-pass filter is supplied are provided to extract signals being analyzed having frequencies higher than the cut-off frequency of the low-pass filter and lower than the cut-off frequency of the high-pass filter; the signals being analyzed are sampled; and data signals on the signals being analyzed for every predetermined time span are supplied to a personal computer; the personal computer extracting from the data signals signal components for each of a plurality of frequency components by means of a plurality of digital filters, and visually displaying the signal components for each of the extracted frequency components.

Claims

1. A biological signal processing system comprising:

a first sensor generating a signal representative of brian waves of a human being;

a second sensor generating a signal representative of other brian waves of a human being;

a differential amplifier means for generating a differential signal representing a difference between the signals of said first and second sensors;

a lowpass filter means for substantially removing frequency portions of the differential signal above an upper cutoff frequency of 30.5 Hz;

a highpass filter means for substantially removing frequency portions of the differential signal below a lower cutoff frequency of 0.5 Hz;

sample means for sampling the differential signal after it has been acted on by said lowpass filter means and said highpass filter means and for forming a data signal in a plurality of time spans;

a plurality of digital filter means, each of said plurality of digital filter means receiving the data signal from said sample means, said each digital filter means removing portions of the data signal above and below a bandwidth of 1 Hz, said each digital filter means having a respective bandwidth positioned at a different spectral location and delivering a filter signal predominately emphasizing said bandwidth of said each digital filter means; and

display means for receiving the filter signals from said each digital filter means and separately displaying a magnitude of each of said filter signals.

2. A biological signal processing system as set forth in claim 1 wherein the magnitudes of said filter signals are displayed in the form of histograms.

3. A biological signal processing system as set forth in claim 2 wherein, together with said histograms, a ratio of the magnitude of an α

wave signal component extracted from the filter signals to the filter signals remaining after the extraction is displayed.

4. A biological signal processing system as set forth in claim 1 wherein said filter signals are expressed in a time series, and the magnitudes of said filter signals are expressed in grades.

5. A biological signal processing system as set forth in claim 1 wherein predetermined frequency components of the filter signals are displayed in the form of topography.

6. A biological signal processing system as set forth in claim 5 wherein said predetermined frequency components are α

waves.

7. A biological signal processing system comprising:

a first sensor generating a signal representative of brian waves of a human being;

a second sensor generating a signal representative of other brian waves of a human being;

a differential amplifier means for generating a differential signal representing a difference between the signals of said first and second sensors;

a lowpass filter means for substantially removing frequency portions of the differential signal above an upper cutoff frequency of 30.5 Hz;

a highpass filter means for substantially removing frequency portions of the differential signal below a lower cutoff frequency of 0.5 Hz;

sample means for sampling the differential signal into sample blocks (x_i) after it has been acted on by said lowpass filter means and said highpass filter means, and for forming a data signal in a plurality of time spans;

a plurality of digital filter means, each of said plurality of digital filter means receiving the data signal from said sample means, said each digital filter means removing portions of the data signal above and below a bandwidth, said each digital filter means having a respective bandwidth positioned at a different spectral location and delivering a filter signal predominately emphasizing said bandwidth of said each digital filter means, and said each digital filter means including a coefficient train (a_j) removing the portions above and below a respective bandwidth, said each digital filter means calculating an instantaneous power spectrum (ppow) by ##EQU11## said digital filter then calculating a power pow(k) by ##EQU12## a present power pow'"'"'(k) is then obtained by forming a time series of said power pow(k) and multiplying said time series of said power pow(k) by weight-average window function coefficients wcof(i'"'"'), where

space="preserve" listing-type="equation">wcof(i'"'"')=cos(π

/2w i'"'"')

(i'"'"'=1, 2, - - - w); and

display means for receiving the filter signals from said each digital filter means and separately displaying a magnitude of each of said filter signals.

8. A biological signal processing system in accordance with claim 7, wherein:

said bandwidth of said each digital filter means is approximately 1 Hz and spaced substantially continuously from approximately 0.5 to 30.5 Hz.

9. A biological signal processing system comprising:

a sensor generating a sensor signal corresponding to biological signals;

sample means for sampling the sensor signal and for forming a data signal in a plurality of time intervals;

a plurality of filter means, each of said plurality of filter means receiving the data signal from said sample means, said each filter means removing portions of the data signal above and below a bandwidth for each time interval, said each filter means having a respective bandwidth positioned at a different spectral location and delivering a filter signal predominately emphasizing said bandwidth of said each filter means for each time interval;

analysis means for performing a frequency analysis on the filter signal of said each filter means for each time interval by using interval integral calculus; and

display means for displaying the frequency analysis of said each filter means and separately displaying a magnitude of each of said filter signals.