JP2770413B2 - Biological abnormality judgment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention is suitable for judging a decrease in arousal level of a driver of a vehicle, an operator of a ship or an aircraft, a simple worker, and other biological abnormalities such as arrhythmia. And a biological abnormality determination device.

(Prior Art) Conventionally, in this kind of biological abnormality determination apparatus, as shown in, for example, JP-A-59-22537, light from a light-emitting diode incident on a finger of a vehicle driver is
When light is received by the phototransistor reflected by the blood flow in the finger, the amount of received light changes according to a change in the amount of the blood flow synchronized with the driver's heartbeat (or a pulse wave corresponding to the heartbeat). When the average value of the cycle of the heartbeat and the variation of the same cycle both increase, using the fact that the driver falls asleep, it is determined that the dozing state is a biological abnormality. is there.

Further, as shown in JP-A-51-84183, the cycle of the pulse averaged several times is multiplied by a number within a certain range to be an average value, and the multiplication result is used as a reference value.
By comparing this reference value with the actual pulse cycle, the arrhythmia can be reported as a biological abnormality, or
As shown in JP-A-105080, there is an apparatus in which an arrhythmia is determined to be a biological abnormality from a difference and a ratio of heart rates obtained from two consecutive heartbeat cycles.

(Problems to be Solved by the Invention) However, in the above-described biological abnormality determination apparatus disclosed in Japanese Patent Application Laid-Open No. 59-22537, since the above-described cycle of the heartbeat also includes a periodic component caused by various disturbances. However, there is a drawback that an error is likely to occur in the determination of a biological abnormality. For this,
Among various disturbances, as for the environmental light, as shown in Japanese Utility Model Application Laid-Open No. 51-8889, an environmental light frequency component such as a fluorescent lamp lit at 50 (Hz) or 60 (Hz) is used. It is also conceivable to drive the light emitting diode in a high frequency range and set the center frequency of the band pallet filter near the driving frequency of the light emitting diode so as to eliminate the influence of ambient light. However, even with such a configuration, in the vehicle, since environmental light exists over a wide frequency component,
In particular, when the frequency components of the pulse wave and the environment light are substantially in the same band and the change in the environment light is large, the influence of the change in the environment light exists as before, and the determination of the biological abnormality becomes unstable.

In such a case, it is also conceivable to employ a peak trigger method for measuring a biological signal, particularly a heartbeat cycle, to detect each peak of both heartbeat signals and measure the time between both peaks to determine the cycle. However, a measurement error may be caused for a heartbeat signal having a plurality of peaks in one cycle or a noisy signal. Further, as shown in Japanese Patent Application Laid-Open No. 58-22029, when an autocorrelation function of a heartbeat signal is calculated and a heartbeat period is measured from a peak interval of the calculation result, the calculation of the autocorrelation value is not performed. Therefore, it takes a considerable time, and it is difficult to shorten the time resolution of the cardiac cycle measurement, that is, the sampling cycle.

Further, each of the above-mentioned JP-A-51-84183 and 53-10508
According to the contents disclosed in Japanese Patent Publication No. 0, even a normal human being may be incorrectly determined to be a biological abnormality due to an inappropriate heart rate fluctuation or a difference or a ratio between successive heartbeat cycles caused by respiratory movements thereof. is there.

Therefore, the present invention has
It is an object of the present invention to determine the presence or absence of an abnormality in a living body with high accuracy in a living body abnormality determining apparatus.

Further, the present invention is intended to quickly and accurately determine the presence or absence of an abnormality in a living body without being affected by ambient light, in order to deal with the above-described problems.

(Means for Solving the Problems) In solving the above problems, according to the present invention, as shown in FIG. 1A, a pulse wave detecting means 1 for sequentially detecting a pulse wave of a living body, and each of the detected pulse waves Calculation means 2 for sequentially calculating the cycle of
Each time the number of calculation cycles of the cycle calculation means reaches a predetermined number, the frequency of the predetermined number of calculation cycles is analyzed, and spectrum distribution data representing the relationship between the frequency (beat ^-1 ) and the intensity of the pulse wave. Frequency analysis means 3 for determining the frequency of the pulse wave based on the spectral distribution data.
A peak determining means 4 for determining a peak of the intensity near 1 (beat ^-1 ) and a peak of the intensity within a frequency of 0.2 to 0.4 (beat ^-1 ) of the pulse wave; There is provided a biological abnormality determination device including a determination unit configured to determine presence or absence of an abnormality corresponding to a decrease in arousal level.

According to this, the pulse wave detecting means 1 sequentially detects the pulse wave of the living body, the cycle calculating means 2 sequentially calculates the cycle of each of the detected pulse waves, and the frequency analyzing means 3 Each time the number of operation cycles reaches a predetermined number, the frequency of the operation cycle for each predetermined number is analyzed to obtain the spectrum distribution data, and the peak determination means 4 determines the frequency of the pulse wave 0.1 (based on the spectrum distribution data). The determination means 5 determines the peak of the intensity near the beat ^-1 ) and the peak of the intensity within the frequency of 0.2 to 0.4 (beat ^-1 ) of the pulse wave. It is determined whether there is an abnormality corresponding to the decrease.

(Effect) As described above, based on the spectrum distribution data obtained at every predetermined number of calculation cycles by the cycle calculation means 2, in addition to the intensity peak near the frequency 0.1 (beat ^-1 ) of the pulse wave of the living body, Since the peak of the intensity within the wave frequency of 0.2 to 0.4 (beat ^-1 ) is also determined to determine the abnormality corresponding to the decrease in the arousal level of the living body, the accuracy of this determination can be improved.

In such a case, the period calculating means 2 determines the rising condition of the subsequent detected pulse wave based on the rising of the detected pulse wave,
If the rising of the detected pulse wave from the pulse wave detecting means 1 following the detected pulse wave is determined according to the determination result, and the period is determined based on the both rising, the preceding pulse wave is always determined. Since the period of the detected pulse wave can be accurately and promptly determined based on the above information, the determination speed of this type of device can be improved while ensuring the improvement of the determination accuracy.

Also, a light emitting element that emits light toward a part of the body of the living body when driven and stops emitting light when not driven, a light receiving element that receives light through the part of the body and generates a light receiving signal according to the amount of received light, Light blocking means for partially blocking the entry of environmental light into the light receiving element; driving means for intermittently driving the light emitting element; a light receiving signal generated from the light receiving element when the light emitting element is driven; and the light emitting element And a difference calculating means for calculating a difference from a light receiving signal generated from the light receiving element when the device is not driven. The pulse wave detecting means 1 calculates the difference between the pulse wave detecting means and the pulse wave. When the light-emitting element is driven under the intermittent driving of the light-emitting element by the driving means, even if the environmental light partially enters the light-receiving element, In the received light signal A difference between a light emission component and an environment light component of the light emitting element and an environment light component in a light reception signal generated from the light receiving element when the light emitting element is not driven is calculated by the difference calculation means, and the pulse wave is detected. The result includes only the pulse wave component of the living body without including the environment light component. Therefore, the abnormality determination corresponding to the decrease in the arousal level of the living body can be accurately performed without being affected by the ambient light.

(Means for Solving the Problems) In solving the above-mentioned problems, the configuration of the present invention is as follows.
As shown in FIG. 1B, a pulse wave detecting means 1 for sequentially detecting a pulse wave of a living body, a cycle calculating means 2 for sequentially calculating a cycle of each of the detected pulse waves, and an average pulse based on each of the detected pulse waves. Mean pulse wave number calculating means 6 for calculating the wave number, current pulse wave number calculating means 7 for calculating the current pulse wave number based on each of the detected pulse waves, and whether the living body is in a normal state according to the average pulse wave number and the current pulse wave number. And a frequency distribution of the pulse wave is obtained by frequency-analyzing each of the calculation cycles based on the determination of the normal state by the first determination means 8. Frequency analysis means 3A, peak determination means 4A for determining the peak of the intensity near the frequency of 0.5 (beat) ^{-1 of the} pulse wave based on the spectrum distribution data, abnormality corresponding to arrhythmia of a living body according to the determined peak Second determination means 5 for determining the presence or absence of A is provided.

(Operation) By configuring the present invention in this way,
The pulse wave detecting means 1 sequentially detects the pulse wave of the living body, the cycle calculating means 2 sequentially calculates the cycle of each detected pulse wave, and the average pulse wave number calculating means 6 calculates the average pulse wave number based on each detected pulse wave. The current pulse wave number calculating means 7 calculates the current pulse wave number based on each of the detected pulse waves. Therefore, when the first determination means 8 determines that the living body is in a normal state according to the average pulse wave rate and the current pulse wave rate, the frequency analysis means 3A performs frequency analysis on each of the calculation cycles and analyzes the spectrum distribution data. The peak determining means 4A determines the peak of the intensity near the frequency 0.5 (beat) ^{-1 of the} pulse wave based on the same spectrum distribution data, and the second determining means 5A It is determined whether there is an abnormality corresponding to the arrhythmia.

(Effect) As described above, based on the spectrum distribution data, the intensity of the pulse wave of the living body under a normal state is determined at an intensity of about 0.5 (beat) ⁻¹ and the abnormality corresponding to the arrhythmia of the living body is determined. The pulse wave of a normal living body is not affected by anyone,
A biological abnormality can always be determined accurately and accurately.

(Example) Hereinafter, a first example of the present invention will be described with reference to the drawings.
FIG. 2 and FIG. 3 show the overall configuration of the biological abnormality determination device according to the present invention. The biological abnormality determination device includes a pulse wave sensor 10 attached to the ear M of the driver of the vehicle, Light emission drive circuit 20 and signal processing circuit 30 connected to pulse wave sensor 10
And a microcomputer 40 connected to the signal processing circuit 30 and a buzzer circuit 50 connected to the microcomputer 40.

The pulse wave sensor 10 includes a clip 11 made of a black material, and the clip 11 includes both clip pieces 11a and 11b.
When each base end is gripped from the outside and pressed against the coil spring 12, both clip pieces 11a and 11b are pivoted about the shaft 11c.
Are tilted outward from each other.On the other hand, when the gripping pressure on both clip pieces 11a and 11b is released, the action of coil spring 12 causes both clip pieces 11a and 11b to rotate about shaft 11c.
Are tilted inward from each other. The photoreflector 13 is supported in parallel with the bottom wall of the concave portion of the clip piece 11a by an appropriate means through the printed circuit board 14 in the inner concave portion of the clip piece 11a.
Is integrated into a single chip by an IC so as to incorporate the light emitting diode 13a and the phototransistor 13b. As the photoreflector 13, a P2826 type manufactured by Hamamatsu Photonics is used.

The spacer 15 is formed in the shape of a square ring plate from a black foam material, and the spacer 15 is fitted with the photoreflector 13 in its hollow portion so that the clip piece 11
It is fixed to the open end of the recess of a. This spacer 15
Has a plate thickness greater than the
When the ear #M is pinched by the pin 11, it has a function of shrinking in the thickness direction to uniformly contact the light receiving / emitting surface of the photoreflector 13 with the surface of the ear #M.

The light emission drive circuit 20 is connected to the printed circuit board 1 by the lead wire 14a.
The light-emitting diode 13a is connected to the light-emitting diode 13a of the photoreflector 13 via 4 and drives the light-emitting diode 13a to emit light toward the ear #M. When the light emitting diode 13a is driven in this manner, light from the light emitting diode 13a enters the ear #M, is reflected by the blood flow in the ear #M, and then enters the phototransistor 13b. . This means that the phototransistor 13b generates a reflected light amount proportional to the blood flow as a pulse wave signal. The signal processing circuit 30
It has an amplifier 31, which is connected to a lead 14b.
Is connected to the phototransistor 13b via the printed circuit board 14, and amplifies the pulse wave signal from the phototransistor 13b to generate an amplified signal. Filter 32 is an amplifier
The noise component is removed from the amplified signal from 31 and the remaining component is generated as a filter signal. The A / D converter 33 converts the filter signal from the filter 32 into a digital signal and generates a digital signal. The sampling cycle of the AD converter 33 is, for example, 1 (msec).

The microcomputer 40 executes a computer program according to the flowchart shown in FIG. 4, and performs arithmetic processing necessary for controlling the buzzer circuit 50 during the execution of the computer program. However, the above-mentioned computer program is stored in the ROM of the microcomputer 40 in advance. Buzzer circuit 50
The buzzer drive circuit 51 drives the buzzer 52 under the control of the microcomputer 40.

In the present embodiment configured as described above, if the driver starts driving and driving the vehicle and activates the device of the present invention, the light generated from the light emitting diode 13a under the driving of the light emitting drive circuit 20 includes: The light enters the ear #M, is reflected by the blood flow in the ear #M, and the reflected light is received by the phototransistor 13b and is generated as a pulse wave signal. At this time, the level of the pulse wave signal changes in proportion to a change in the amount of the blood flow synchronized with the driver's pulse wave.

The pulse wave signal from the phototransistor 13b is amplified as an amplified signal by the amplifier 31, the amplified signal is generated as a filter signal by the filter 32, and the filter signal is digitally converted by the AD converter 33. The digital signal is given to the microcomputer 40. The microcomputer 40 starts the execution of the computer program at step 60a in accordance with the flowchart of FIG. 4 at the same time as the operation of the device of the present invention, and initializes the program at step 61. Proceed.

Then, in the same step 62, the microcomputer 40 determines, based on the difference ΔA (see FIG. 5) between the respective values (hereinafter, referred to as respective sampling digital values) of both continuous digital signals from the A / D converter 33, It is determined whether or not the pulse wave rising amplitude condition is satisfied. At the present stage, since the determination in step 62 is an initial stage, the rising amplitude condition is satisfied when the condition that the difference ΔA belongs to the difference ΔA ₀ between the predetermined two sampling digital values is continuously satisfied five times or more. Is determined. However, the difference ΔA ₀ between the predetermined two sampling digital values is in the range of (1/20) or more and (1/5) or less of the general pulse wave amplitude A ₀ , Corresponds to the rising angle range. Note that the difference ΔA ₀ is stored in the ROM of the microcomputer 40 in advance.

At this stage, since the determination in step 62 is still the first time, the microcomputer 40 determines “NO” in step 62, and determines “NO” in step 63 based on the uncalculation of the pulse wave period T. Is determined, and in step 64, “NO” is determined based on the number of operations N = 0 in the cycle T. Hereafter, each step 62, 6
During the repetition of the calculations passing through 3, 64, if the determination in step 62 becomes "YES", the microcomputer 40
However, based on the determination that a series of sampled digital values from the A / D converter 33 correspond to the rise of the driver's pulse wave, in step 62a, The period T = T ₀ is calculated, and the amplitude A = A ₀ is calculated from the difference between the maximum value and the minimum value of each sampling digital value.

Thereafter, the microcomputer 40, at step 63, under the A = A _0, determines "YES", through the step 63a, at step 64, based on number of operations N = 1 again "NO "
Is determined. However, the predetermined number N ₀ corresponds to the number of periods T required for the frequency analysis of the pulse wave, and corresponds to the ROM of the microcomputer 40.
Is stored in advance. Next, if the determination in step 62 becomes “YES” in the same manner as described above based on a series of sampling digital values sequentially generated from the AD converter 33, based on the determination that one pulse wave of the driver has risen, In step 62a, the microcomputer 40 first executes "Y
The pulse wave period T is determined from the number of sampling digital values between the sampling digital value that was premised on the determination of “ES” and the sampling digital value that was premised on the determination of “YES” in step 62 in this time. Is calculated, and the amplitude A of the pulse wave is calculated from the difference between the maximum value and the minimum value of these sampling digital values.

Next, the microcomputer 40 determines "YES" in step 63 based on the latest amplitude A in step 62a, and in step 63a, the value of (1/5) of the latest amplitude A in step 62a and ( 1/20) the difference between the values ΔA
₁ and calculated at step 64, N = 2 <N ₀ under the "N
O ". However, the difference ΔA ₁ corresponds to the rising angle width of the pulse wave having the latest amplitude A (that is, the angle width by the rising angle upper limit and the rising angle lower limit of the pulse wave). After that, step 63a
When the determination in step 62 according to a series of sampled digital values from the A-D converter 33 becomes "YES" in the same manner as described above in connection with the difference .DELTA.A ₁ in execution of the operation the microcomputer 40 in step 62a after to go into.

Thereafter, the same arithmetic processing as described above is repeated, and when the determination in step 64 becomes “YES” under N = N ₀ ,
The microcomputer 40 repeats the determination of “NO” and repeats the calculation of each of steps 62 to 64 until a predetermined time (for example, 5 seconds) has elapsed from the previous frequency analysis in step 65. When the determination at step 65 is "YES", the microcomputer 40 determines at step 65a the autoregressive model based on the following equation (1) based on the latest N ₀ periods T at step 62a. The frequency analysis is performed on the fluctuation of the period T due to.

However, 0 ≦ F ≦ 0.5 (beat ⁻¹ ). Also, P
(F) represents a power spectrum density function, and a (K) represents a linear prediction function in the following equation (2). Also, ▲
S ² _Z ▼ (N) represents the variance of the residual Z (t) in equation (2).

Here, (t) represents a series of the period T. The equations (1) and (2) are stored in the ROM of the microcomputer 40 in advance.

Based on the frequency analysis in step 65a as described above, frequency spectrum data (for example,
6) is obtained, the microcomputer 40
However, in step 65b, the intensity G ₀ near the frequency “0 (beat ⁻¹ )” is determined based on the frequency spectrum data.
If the intensity G ₀ is equal to or _larger than the threshold value G ₀₀ , the microcomputer 40 determines “NO” in step 66, and performs the processing after step 62 again. On the other hand, if G ₀ <G ₀₀ , the microcomputer 40 determines “YES” in step 66.
It determines that, in step 66a, based on the frequency spectrum data to determine the frequency "0.1 (beat ^-1)" intensity peak value G ₁ in the vicinity.

In this stage, smaller than the threshold value G ₁₀ is the intensity peak value G _1, the microcomputer 40 returns the discriminated computer program as "NO" in the 62 subsequent step in step 67. On the other hand, if G ₁ ≧ G ₁₀ , the microcomputer 40 determines “YES” in step 67, and proceeds to step 67a
At the frequency `` 0.
2 to 0.4 to determine the intensity peak value G ₂ in (beat ^-1) ". Thus, if the intensity peak value G ₂ is smaller than the threshold value G _20, "NO" microcomputer 40 at step 68
And the computer program is returned to step 62 or later. On the other hand, if G ₂ ≧ G ₂₀ , the microcomputer 40 determines “YES” in step 68.

However, the above-described threshold values G ₀₀ , G ₁₀ , and G ₂₀ are determined as follows. In general, when the driver is driving the vehicle, as the driver's arousal level decreases, the frequency spectrum characteristic of the driver's pulse wave changes as shown in FIG. Therefore, the frequency “0 (bea
t ^-1) "set somewhat larger threshold G ₀₀ than the strength of the case, define the threshold G ₁₀ to the intensity following values when the frequency" 0.1 (beat ^-1) ", and the frequency" 0.2 to 0.4 (beat ^- be determined threshold G ₂₀ below the intensity peak value at ¹⁾ _{", G 0 <G 00, G} 1 ≧ G 10 and G ₂
Lowering three conditions of ≧ G ₂₀ exceeds the allowable limit of awareness of the driver when both satisfied can reliably determine the biological abnormality. Therefore, G ₀₀ , G _10, and G ₂₀ are determined and stored in the ROM of the microcomputer 40 in advance as described above.

When the determination in step 68 is "YES" as described above, the microcomputer 40 determines in step 68a that the alarm output signal Is generated, and in response to this, the buzzer circuit 50 causes the buzzer drive circuit 51 to sound the buzzer 52. Thereby, the driver can surely recognize that it is immediately before the drowsy driving. In such a case, the recognition accuracy can be improved in connection with G ₀₀ , G ₀₁ , G ₂₀ based on the quick calculation of the period T performed in connection with each of the steps 62 to 64.

Next, a second embodiment of the present invention will be described. In this embodiment, a light-shielding cover 70 is attached to the pulse wave sensor 10 described in the first embodiment as shown in FIGS. In addition, the light emission drive circuit 20 and the amplifier 31 and the filter 32 of the signal processing circuit 30 described in the first embodiment are used.
Instead of adopting an electronic circuit configuration as shown in FIG. 9, there is a feature in the configuration.

The light-shielding cover 70 is made of black flexible foam material.
As shown in FIG. 8 and FIG. 8, the light shielding cover 70 is formed in a substantially U-shape.
Thus, the clip pieces 11a and 11b are attached to the clip 10 from outside. Shield plate
Reference numeral 71 designates the ear ぷ M as a reference and is located on the opposite side of the driver's head, while the light shielding plate 72 is located between the ear ぷ M and the driver's head. The upper portion 71a of the light-shielding plate portion 71 corresponding to the upper portion of the clip piece 11b is spread in a flat plate shape in the left-right direction in the drawing so as to have the shape shown in FIG. Is prevented from entering the photoreflector 13 and its surroundings.

In such a case, if the area of the upper portion 71a of the light-shielding plate portion 71 is set to about 5 (cm ² ), the influence of environmental light can be removed by about 90 (%). On the other hand, the light shielding plate portion 72 has, in principle, an upper portion 72a having the same shape as the upper portion 71a of the light shielding plate portion 71, but since the upper portion 72a is located on the head side, the upper portion 71a has a circular shape. Parts are omitted. In FIGS. 7 and 8, reference numeral 73 denotes a U-shaped stopper. The stopper 73 sandwiches the base portions 71b, 72b of the light shielding plate portions 71, 72 from outside. Then, the light shielding cover 70 is fixed to the clip 1.

In FIG. 9, an oscillation circuit 80 generates an oscillation pulse from an output terminal 81 at an oscillation frequency of about 6 (KHz), and outputs a first synchronization pulse in synchronization with the rise of the oscillation pulse.
A second synchronizing pulse is generated from an output terminal 83 in synchronization with the falling edge of the oscillation pulse. Drive circuit
90 drives the light emitting diode 13a in response to an oscillation pulse from the oscillation circuit 80. In such a case, the oscillation circuit 80
The light emission illuminance ratio of the light emitting diode 13a at the time of rising of the oscillation pulse from the light emitting diode and at the time of falling of the same oscillation pulse is about 5. The bandpass filter 100 receives the pulse wave signal (including the ambient light component) from the phototransistor 13b, attenuates the ambient light component in the pulse wave signal, and drives the drive frequency of the drive circuit 90 (that is, the frequency of the oscillation pulse). A component centered on the frequency (i.e., the pulse light component of the light emitting diode 13a corresponding to the pulse wave component) is amplified together with the remaining environmental light component to generate a filter signal.

The hold circuit 110 holds the filter signal from the band-pass filter 100 in response to the first synchronization pulse from the oscillation circuit 80. On the other hand, the hold circuit 120 holds the filter signal from the bandpass filter 100 in response to the second synchronization pulse from the oscillation circuit 80. Accordingly, the hold circuit 110 has a function of holding the pulse light component and the ambient light component from the light emitting diode 13a in relation to the first synchronization pulse.
Is the light emitting diode 13 in relation to the second synchronization pulse.
It can be said that it has a function of holding the dimming component and the ambient light component from a. Each of the hold circuits 110 and 120 is composed of a switching element S (TC4053BE of Toshiba IC) and a hold capacitor C. The differential amplifier 130 amplifies each of the hold signals from the two hold circuits 110 and 120 by AC differential amplification, and generates the amplified result as a differential amplified signal. This means that the differential amplified signal contains only the pulse wave component based on the dimming component from the light emitting diode 13a because the ambient light components of the respective hold signals are canceled each other. Other configurations are the same as those in the above embodiment.

Here, the basis of the electronic circuit configuration shown in FIG. 9 will be described. In general, blood flow reflected light with respect to environmental light also enters the phototransistor 13b. The so-called photoelectric pulse wave detection method described in the above embodiment is a method that is sensitive to changes in ambient light. For this reason, the present inventors, the light emitting diode 13a
When the relationship between the illuminance of the mixed light of the ambient light and the ambient light and the level of the pulse wave signal from the phototransistor 13b was examined, an upwardly convex curve L as shown in FIG. 10 was obtained. Thus, according to the curve L, the level of the pulse wave signal has an inflection point P with respect to the illuminance of the mixed light, and below the inflection point P, the level changes almost linearly as the illuminance decreases. .

By the way, the mixed light can be classified into light from the light emitting diode 13a and environmental light.If the amount of light generated from the light emitting diode 13a is made variable, the ambient light component is curved from the component of the pulse wave signal from the phototransistor 13b. L can be extracted. However, before and after the inflection point P, the level of the pulse wave signal differs for the variable light from the light emitting diode 13a. Therefore, if the illuminance of the mixed light is always kept lower than the inflection point P by adopting the light-shielding cover 70 and blocking the ambient light as described above, the pulse wave is not affected by the change of the ambient light. The signal can always be stabilized.

In view of the above, the electronic circuit configuration shown in FIG. 9 was adopted in order to decompose the mixed light using the curve L as described above, assuming that the ambient light was partially blocked by the light-shielding cover 70.

In the present embodiment configured as above, if the oscillation circuit 80 sequentially generates the oscillation pulse and the first and second synchronization pulses, the driving circuit 90 sequentially responds to each of the oscillation pulses to pulse the light emitting diode 13a. Drive. Then, the light emitting diode 13a sequentially emits light in a pulsed manner at the drive frequency of the drive circuit 90, and this pulsed light is sequentially incident on #M. Thereafter, each pulse light incident into the ear #M is reflected by the blood flow in the ear #M, enters the phototransistor 13b, and is generated as a pulse wave signal. In such a case, the level of the pulse wave signal is the sum of the reflected light amount of each pulsed light and the light amount of the environmental light proportional to the change in the amount of the blood flow, or the reduced light reflected light amount of each pulsed light and the light amount of the environmental light. Equivalent to sum.

Next, the band-pass filter 100 receives the pulse wave signal from the phototransistor 12b, attenuates the ambient light component in the pulse wave signal, amplifies the attenuated component together with the remaining components, and generates a filter signal. Then, the hold circuit 11
0 holds the level of the filter signal from the band-pass filter 100 and generates it as a hold signal in response to each first synchronization pulse from the oscillation circuit 80, while the hold circuit 120 generates the hold signal from the oscillation circuit 80. In response to each second synchronization pulse, the level of the filter signal from the band-pass filter 100 is held and generated as a hold signal. In such a case, the level of the hold signal from the hold circuit 110 corresponds to the rise of the oscillation pulse from the oscillation circuit 80, while the level of the hold signal from the hold circuit 120 corresponds to the fall of the oscillation pulse from the oscillation circuit 80. I do.

Thereafter, the differential amplifier circuit 130 performs AC differential amplification of each hold signal from both the hold circuits 110 and 120, and generates this as a differential amplified signal. In such a case, this differentially amplified signal contains only a pulse wave component. Therefore, the differential amplified signal generated from the differential amplifier circuit 130 in this manner is converted into an AD signal.
The converter 40 converts the digital signal to a microcomputer 40.
, It is possible to accurately give a warning that the driver is about to fall asleep just before driving as a biological abnormality without being affected by ambient light. Other functions and effects are the same as those of the above embodiment.

Next, a third embodiment of the present invention will be described. In this embodiment, the flowchart of FIG. 4 for specifying the computer program described in the first embodiment is shown in FIG.
A computer program which is changed as shown in FIG. 11 and which is specified by the change flowchart (hereinafter referred to as a changed computer program) is stored in advance in the ROM of the microcomputer 40 in place of the computer program referred to in the first embodiment. This configuration has a feature in its configuration. Other configurations are the same as in the first embodiment.

In this embodiment configured as described above, the changed computer program is executed in step 62a similarly to the first embodiment.
After proceeding to (see FIGS. 4 and 11), the microcomputer 40 determines in step 62b the latest operation number N based on the following equation (3), the latest cycle T in step 62a, and the latest cycle T in step 62b. calculating a parallel pulse rate P ₀₀ corresponding to the average pulse rate P ₀₀ a of the preceding.

However, this equation (3) is the ROM of the microcomputer 40.
Is stored in advance.

When the determination of “NO” in step 63 or the arithmetic processing in step 63a is completed, the microcomputer 40 determines in step 63b “NO” based on N <3 in the same manner as in the first embodiment. Then, the changed computer program returns to step 62. Thus, when the determination in step 63b is “YES” in the process of repeating the cyclic operation from step 62 to step 63b, the microcomputer 40 executes the change computer program in step 63b.
Proceed after c. At this stage, the three most recent consecutive periods determined in step 62a are T = T _n-2 , T = T _n-1 and T
= Tn, T ₀₁ ≧ T _n-1 ≧ T ₀₂ and Is satisfied, the microcomputer 40 executes each step 63
It is sequentially determined to be "NO" at c, 63d, and 63e.

However, each code T ₀₁ and T ₀₂ described above represents a threshold for arrhythmia determination are determined based on the following grounds. In other words, in order to reliably distinguish between the pulse wave period during normal human exercise and the pulse wave period during arrhythmia, the period of a certain pulse wave and the period of each of the pulse waves before and after it are determined. An arrhythmia is determined only when the deviation exceeds the allowable limit. That is, T ₀₁ ≧ T _n-1 ≧ T ₀₂ and T ₀₁ , T ₀₂ , so that it is considered to be an arrhythmia when
Is stored in the ROM of the microcomputer 40 in advance.

From the above, it can be said that the determination of “NO” in step 63e indicates that the pulse wave is normal. On the other hand, for example, when the period T _n-1 is shifted from T _n-2 and Tn as shown in FIG. 12 and FIG.
However, in step 63d or 63e, "YES" is determined, and in step 68a, an alarm output signal is generated as in the first embodiment, and in response to this, the buzzer circuit 50 sounds the buzzer 52. Thus, the driver can recognize the arrhythmia unless immediately before falling asleep, regardless of who is the normal pulse wave.

Also, as in the first embodiment, when the determination of “YES” in step 64 is made, the microcomputer 4
0 calculates the current pulse wave number P ₀ based on the latest N ₀ periods in step 64a, and in step 64b calculates the sum of the latest average pulse wave number P ₀₀ and the threshold value P ₀₁ for step 62b. Pulse wave number P ₀
Is determined by comparison. However, the threshold value P ₀₁ is stored in advance in the ROM of the microcomputer 40 corresponds to the upper limit value of the pulse rate in the normal state of a normal person. Then step 6
If the determination in step 4b is "YES", the microcomputer 40 performs frequency analysis in step 65a in the same manner as in the first embodiment based on the determination that the driver's pulse wave is in a normal state. in step 65c, according to the frequency spectral data based on the same frequency analyzed to determine the frequency "0.5 (beat) ^-1" intensity peak value G ₃ in the vicinity. In this stage, the microcomputer 40 determines "NO" in step 68A if the intensity peak value G ₃ threshold G ₃₀ or less. On the other hand, if G ₃ > G ₃₀ , the microcomputer 40 determines “YES” in step 68A.
Is determined.

However, it and the threshold G ₃₀ and the intensity peak value G ₃ and a value near "0.5 (beat) ^-1" is as follows. When the frequency spectrum distribution of the pulse wave of a normal person in a normal state was examined in relation to the intensity, a curve La was obtained as shown in FIG. On the other hand, when the frequency spectrum distribution of the pulse wave of an arrhythmic person was examined in the same manner, a curve Lb was obtained as shown in FIG. As is clear when comparing both curves La and Lb,
If the frequency is around “0.5 (beat) ⁻¹ ”, the presence or absence of arrhythmia can be reliably distinguished. Therefore, the intensity peak value G _{3 is set} to 0.5 (beat)
The strength in the vicinity of ^-1, and the threshold value G ₃₀ both curves La, and an intermediate value in the vicinity of 0.5 (beat) ^-1 of the intensity on the Lb. Note that the threshold G
_Reference numeral ₃₀ is stored in the ROM of the microcomputer 40 in advance.

Thus, when the determination of “YES” is made in step 68A as described above, the microcomputer 40 makes the buzzer 52 sound in response to the generation of the alarm output signal in step 68a. Thus, the driver can recognize an arrhythmia unless the driver is immediately before falling asleep. In such a case, since the arithmetic processing of each of steps 64 to 68a is performed after the arithmetic processing of each of steps 63b to 63e, the accuracy of determining a biological abnormality as an arrhythmia is further improved.

In practicing the present invention, the rising amplitude condition of the pulse wave may be determined not only by the amplitude of the immediately preceding pulse wave but also by the amplitude of the preceding pulse wave. In such a case, if the rise is equal to or more than a predetermined value in the rise amplitude condition, the rise may be determined to be noise and then the rise determination may not be performed for a certain period of time.

In practicing the present invention, a warning may be given by a display unit, a voice synthesizing unit or the like without being limited to the buzzer circuit 50.

Further, in implementing the present invention, the area of each light shielding plate portion of the light shielding cover 70 may be appropriately changed as necessary.

Further, the present invention is not limited to vehicles, and may be applied to determination of arousal level or arrhythmia of operators of ships or aircraft, simple workers in factories, patients, etc. Further, a photocoupler may be employed instead of the photoreflector 13 to detect the transmitted light amount of the blood flow of the ear #M.

Moreover, the practice of the present invention, the frequency for calculating the pulse rate currently may be implemented by modifying as needed not limited to N _0.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams corresponding to the respective claims 1 and 4, respectively. FIGS. 2 and 3 are overall structural views showing a first embodiment of the present invention. Is a flowchart showing the operation of the microcomputer in FIG. 3, and FIG.
FIG. 3 is a time chart of the sampling digital value of the AD converter in FIG. 3, FIG. 6 is a frequency characteristic diagram of the intensity of the driver's pulse wave, and FIG. 7 is a light shielding cover for the pulse wave sensor of FIG. FIG. 8 is a sectional view showing the assembled state, FIG.
9 is a main part circuit diagram in which the circuit configuration of FIG. 3 is partially changed, FIG. 10 is a graph showing the relationship between the level of the pulse wave signal and the illuminance of the mixed light, and FIG. 11 is a diagram of FIG. 12 and 13 are time charts showing the relationship between the pulse wave and the cycle, and FIG. 14 is a frequency characteristic diagram of the intensity of the pulse wave in relation to the presence or absence of arrhythmia. is there. EXPLANATION OF SYMBOLS 10: pulse wave sensor, 13: photo reflector, 20: light emission drive circuit, 30: signal processing circuit, 40: microcomputer, 50
... buzzer circuit, 70 ... light shielding cover, 80 ... oscillation circuit, 110, 12
0: Hold circuit, 130: Differential amplifier circuit, M: Earpiece.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shinji Iwama 1-1-1 Showa-cho, Kariya-shi, Aichi Japan Inside the Denso Corporation (72) Inventor Koichi Takagi 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Nihon Denso Co., Ltd. (72) Inventor Takeshi Yoshinori 1-1-1 Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (56) References Japanese Utility Model 1987-202806 (JP, U) (58) Field surveyed (Int. ⁶ , DB name) A61B 5/02

Claims (4)

(57) [Claims] 1. A pulse wave detecting means for sequentially detecting a pulse wave of a living body, a cycle calculating means for sequentially calculating a cycle of each of the detected pulse waves, each time the number of calculation cycles of the cycle calculating means reaches a predetermined number Frequency analysis means for frequency-analyzing the operation cycle for each predetermined number to obtain spectrum distribution data representing the relationship between the frequency (beat ^-1 ) and the intensity of the pulse wave; and Frequency 0.1
Peak determining means for determining the peak of the intensity near (beat ^-1 ) and the peak of the intensity within the frequency of 0.2 to 0.4 (beat ^-1 ) of the pulse wave; A living body abnormality determining device, comprising: determining means for determining the presence or absence of an abnormality corresponding to a decrease in blood pressure. 2. The cycle calculating means determines a rising condition of a succeeding detected pulse wave based on a rising of the detected pulse wave,
The method according to claim 1, wherein the rising of the detected pulse wave from the pulse detecting unit following the detected pulse wave is determined according to the determination result, and the period is determined based on the rising both. The biological abnormality determination device according to claim 1. 3. A light-emitting element which emits light toward a part of the body of a living body when driven and stops the emission when not driven, and a light-receiving element which receives light via the part of the body and generates a light-receiving signal according to the amount of received light. An element, a light blocking unit for partially blocking the entry of environmental light into the light receiving element, a driving unit for intermittently driving the light emitting element, and a light receiving signal generated from the light receiving element when the light emitting element is driven. And a difference calculating means for calculating a difference from a light receiving signal generated from the light receiving element when the light emitting element is not driven. The pulse wave detecting means is provided with: The first feature is that it is detected as a pulse wave.
The biological abnormality determination device according to item 2 or 2. 4. A pulse wave detecting means for sequentially detecting a pulse wave of a living body, a period calculating means for sequentially calculating a period of each of the detected pulse waves, and an average pulse wave number based on each of the detected pulse waves. Means for calculating a current pulse wave rate based on each of the detected pulse waves; and first means for determining whether or not the living body is in a normal state according to the average pulse wave rate and the current pulse wave rate. Determining means; and frequency analysis of each of the calculation cycles based on the determination of the normal state by the first determining means, the frequency of the pulse wave (beat ^-1 )
Frequency analysis means for obtaining spectral distribution data representing the relationship between the intensity and the intensity, the frequency of the pulse wave 0.5 based on the spectral distribution data
A biological abnormality determining device comprising: peak determining means for determining a peak of the intensity near (beat ^-1 ); and second determining means for determining whether there is an abnormality corresponding to arrhythmia of a living body in accordance with the determined peak.