JPH05184548A - Pulse rate measuring instrument - Google Patents

Abstract

PURPOSE:To remove artifacts and to measure pulse rates with high accuracy by calculating the weight average signal of plural kinds of pulse wave signals, subtracting the weight average signal from the respective pulse wave signals to correct respective pulse waves and calculating the pulse rate in accordance with the corrected pulse wave signals. CONSTITUTION:The pulse rate measuring instrument measures the pulse rate in accordance with plural kinds of the pulse wave signals outputted from a tonometer sensor. The weight average signal of the respective pulse wave signals is calculated means in accordance with a predetermined weighting coefft. in such a case. The weight average signal is subtracted from the respective pulse wave signals and the respective pulse wave signals are corrected by a pulse wave signal correcting means. Further, the pulse rate is calculated by a pulse rate calculating means in accordance with the corrected pulse wave signals. The calculated pulse rate is displayed by a display means. As a result, noises and motion artifacts are removed and the high precision pulse rate is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse rate measuring device for monitoring a pulse rate by measuring and displaying the pulse rate,
In particular, it relates to a technique for obtaining a pulse rate with high accuracy by means of removing noise and motion artifacts.

[0002]

BACKGROUND OF THE INVENTION The present invention is a device for measuring a pulse rate with high accuracy and displaying the pulse rate. Particularly, in a pulse rate measuring device having a plurality of pressure sensitive sensor elements, an artifact is detected and removed. It is intended to improve the measurement accuracy of the pulse rate by the means.

As a background for this, there have been conventionally known techniques for measuring the pulse rate and techniques for removing pulse artifacts. For example, U.S. Pat. No. 4,409,983 describes a pulse rate measuring device having a plurality of transducers coupled to an averaging circuit and a differential amplifier. This device is useful for removing motion artifacts from a signal indicating vibration associated with heartbeat. Also, U.S. Pat.Nos. 4,307,728, 4,202,350,
No. 4,667,680, No. 4,239,048, No. 4,181,134, No.
No. 4,456,959 also proposes a technique for removing motion artifacts. Conventionally, windowing (time gate processing) is used as a means to reduce false signals.
Techniques, averaging techniques, and autocorrelation algorithms are used.

[0004]

In the above-mentioned conventional pulse rate measurement technique, there are many factors that cause a decrease in measurement accuracy.

First, in many of the conventional techniques, it is difficult to remove motion artifacts and noise artifacts, and the above-mentioned adverse effect is remarkable particularly in an apparatus using a single sensor element (US Pat. No. 4,202). , 35
0 and 4,239,048). Such a device does not have a means for separately accepting a pulse wave signal containing artifacts and an artifact signal. Therefore, some means is needed to compensate or eliminate measurement errors due to motion artifacts and other artifact signals. As this means, a signal processing means utilizing a filtering technique or a windowing technique is often applied.

Even in the technique of pulse rate measurement by a pulse wave sensor using a plurality of sensor elements, an erroneous signal is often judged as a pulse wave signal, or even a true pulse wave signal may not be detected. is there. Since the occurrence of artifacts is unavoidable in actual pulse rate measurement, high measurement accuracy cannot be obtained unless the above-described technique for compensating for malfunction is applied to pulse rate measurement.

The present invention eliminates the inconvenience associated with a pulse wave sensor for collecting pulse waves based on the principle of the tonometric method. In the present invention, algorithms are used in the process of processing the pulse wave signal and calculating the pulse rate to compensate for signal-related malfunctions that may occur during pulse rate measurement.

The principle of the tonometric method is, for example, US Pat. Nos. 3,219,035, 4,799,491, and 4,802,488.
It is mentioned in the issue. Also, "Medical Devices and Medical Equipment Dictionary" Vol. 4 (JGWebster, John Wiley, Sons, 19
1988), "Tonometry, Arterial", and other publications. All of these references discuss tonometric methods applied to the measurement of arterial pressure.

When measuring the arterial pressure, it is desirable to flatten a part of the arterial wall by applying a suitable pressing force to the tonometer sensor as described in the above-mentioned reference.
Regarding pulse rate measurement, it is not always important to flatten the arterial wall, and a weaker pressing force than to flatten the arterial wall may be applied. Therefore, the discomfort of the measurement subject is reduced as compared with the case of measuring the blood pressure.

In view of the above circumstances, the present invention has been made to solve the above-mentioned inconvenience in the conventional pulse rate measurement technique.

A first object of the present invention is to improve the measurement accuracy in an apparatus for pulse rate measurement by the tonometric method using a sensor element array in which a plurality of sensor elements are arranged.

A second object of the present invention is to subtract the weighted average value of the pulse wave signals based on a predetermined weight value from each of the plurality of pulse wave signals corresponding to the plurality of sensor elements,
The purpose is to remove motion artifacts from the pulse wave signal.

[0013]

To achieve the above object, the gist of the present invention is to provide a single sensor element composed of a plurality of sensor elements, as shown in the claim correspondence diagram of FIG. Comprises a tonometer sensor having an array,
A pulse rate measuring device for obtaining a highly accurate pulse rate based on a plurality of types of pulse wave signals output from the tonometer sensor, (a) the plurality of types based on a predetermined weighting coefficient A weighted average signal calculation means for calculating a weighted average signal of the pulse wave signal, and (b) by subtracting the weighted average signal calculated by the weighted average signal calculation means from each of the plurality of types of pulse wave signals, A pulse wave signal correcting means for correcting the pulse wave signal of the kind, (c) a pulse rate calculating means for calculating a pulse rate based on the corrected pulse wave signal corrected by the pulse wave signal correcting means, (d) Display means for displaying the pulse rate calculated by the pulse rate calculation means.

[0014]

With this configuration, the weighted average signals of the plurality of types of pulse wave signals calculated by the weighted average signal calculation means on the basis of the predetermined weighting coefficient are converted into the plurality of types of pulse wave signals by the pulse wave signal correction means. A plurality of types of pulse wave signals are corrected by being subtracted from each of the wave signals. Then, the pulse rate is calculated based on the corrected pulse wave signal by the pulse rate calculation means, and is displayed by the display means.

[0015]

EFFECTS OF THE INVENTION Motion artifacts caused by movements of a living body such as a walk affect each of a plurality of sensor elements to the same degree, while a pulse wave signal accurately reflecting arterial pressure is: It only acts on sensor elements located directly above the artery or very close to it. Therefore, when the motion artifacts act equally on the plurality of sensor elements, the weighted average signal of the plurality of types of pulse wave signals that accurately reflects the motion artifacts is subtracted from each pulse wave signal. A corrected pulse wave signal from which motion artifacts have been removed is obtained. Therefore, according to this pulse rate measuring device,
By calculating the pulse rate from the corrected pulse wave signal,
Artifacts such as motion artifacts are preferably compensated for and high pulse rate reliability is obtained.

Preferably, the pulse rate measuring apparatus is (e) an autocorrelation for calculating an autocorrelation value indicating an autocorrelation degree within a predetermined period in at least one of the plurality of types of corrected pulse wave signals. A value calculating means, and (f) the autocorrelation value calculated by the autocorrelation value calculating means is within the range of a predetermined correlation coefficient, the autocorrelation determination to determine that the corrected pulse wave signal is valid And means.

The preferred pulse rate measuring apparatus further preferably includes (g) autocorrelation processing delay means for operating the autocorrelation value calculation means and the autocorrelation determination means after a predetermined period from the time of systole.

Preferably, the pulse rate measuring device comprises (h) a slope value calculating means for calculating a slope value in at least one of the plurality of types of corrected pulse wave signals, and (i) the slope value calculating means. The method further includes a slope determination unit that determines that the corrected pulse wave signal is valid based on the calculated slope value being higher than a predetermined threshold slope value.

Preferably, the pulse rate measuring device comprises (j) a systolic time point detecting means for detecting a systolic time point in at least one of the plurality of types of corrected pulse wave signals, and (k) the systolic time point. The systolic cycle, which is the time interval at the time of systole detected by the detection means, is compared with a predetermined reference cycle, and when the systolic cycle exceeds the reference cycle, the systolic cycle is set to the current systole. If the systolic cycle is less than a predetermined range, the systolic cycle that determines the current systolic cycle based on the sum of the systolic cycle and the previously determined systolic cycle. And cycle determining means.

Preferably, the pulse rate measuring apparatus is: (l) In at least one of the plurality of types of pulse wave signals, a pulse wave signal exceeding a predetermined upper limit value is determined to be an artifact signal and an artifact is detected. The apparatus further includes excess pulse wave signal removing means for removing the signal.

[0021]

FIG. 1 shows a pulse rate measuring apparatus 1 which is a preferred embodiment of the present invention. This pulse rate measuring device 1
Includes a tonometer sensor 2 and a case 3 that houses a circuit having a signal processing function and a display function. The tonometer sensor 2 is attached to a gimbal member 9 connected to the case 3 via a spring 4. The spring 4 has a sensor position adjusting portion 5, and the gimbal member 9 is connected to the spring 4 in the sensor position adjusting portion 5.

FIG. 2 shows the device of FIG. 1 in more detail. Note that the same names as those used for the same components disclosed in FIG. 1 are used. The sensor adapter 12 is rotatably attached to the gimbal member 9 by inserting a pin (not shown) on the second rotation axis A2 of the gimbal member 9, and the tonometer sensor 2
Are fixed to the sensor adapter 12. The spring mounting pad 11 is rotatably mounted on the gimbal member 9 by inserting a pin (not shown) along the first rotation axis A1 of the gimbal member 9. The spring 4 and the gimbal member 9 are connected via 11. The tonometer sensor 2 is a case 3 shown in FIG. 4 by a flat cable 10 which is a flexible printed circuit board.
Operatively coupled to the circuitry within.

The tonometer sensor 2 is a single array composed of a plurality of pressure sensitive sensor elements 15. Standard photographic printing fabrication techniques may be applied to the assembly of the tonometer sensor. According to the analysis result based on the test, about 3 to 6 sensor elements 15 are required to obtain a suitable measurement accuracy in pulse rate measurement.
In the measuring device of this embodiment, a single sensor element 15
Even in this case, it is possible to expect measurement with higher accuracy than before. The above-mentioned components of the pulse rate measuring device 1 will be referred to in the following description.

Returning to FIG. 1, the pulse rate measuring device 1 is preferably attached to the wrist of a living body like a wristwatch. When the pulse rate measuring device 1 is attached to the wrist of the living body, the tonometer sensor 2 is positioned on the radial artery, and the case 3 is attached by being wound on the opposite side of the wrist from the tonometer sensor 2. The case 3 supports the spring 4 at one end thereof in a cantilevered manner, and the wearing band 8 is fastened by the latch 7 in a state in which the flexible portion 8a thereof is tightened, so that the case 3 has a predetermined body part. It is designed to be held in position. The mounting band 8 has a band protection member 6 so that the tonometer sensor 2, the gimbal member 9 and the spring 4 do not come into direct contact with the mounting band 8. In addition, a part of the band protection member 6 is cut out from the inside to form a box-shaped portion. In this part, all of the tonometer sensor 2, the gimbal member 9, and the spring 4 are provided with the mounting band 8. The tonometer sensor 2, the gimbal member 9 and the spring 4 are shaped so as to be fitted in the tonometer sensor 2 without contacting each other.

The tonometer sensor 2 is held on the artery by a thin spring 4 supported in a cantilevered manner on the case 3 so that the spring 4 is wound around the wrist. The gimbal member 9 has a U-shaped base on one side surface (see FIGS. 1 and 2), and the tonometer sensor 2 is connected to the spring 4 via the gimbal member 9. The tonometer sensor 2 is supported by the spring 4 so that it is positioned horizontally with respect to the wrist while being attached to the living body. The gimbal member 9 is capable of rotating about two rotation axes A1 and A2 which are orthogonal to each other by about 20 degrees. The positions of the tonometer sensor 2 and the gimbal member 9 on the spring 4 are adjusted by a sensor position adjusting section 5 which is a part of the spring 4.

The pressing force of the tonometer sensor 2 is adjusted to such an extent that a part of the radial artery can be flattened within a range that does not cause discomfort to the subject. The optimum pressing force is about 100g to 50
It is within the range of 0 g and is different for each living body. In order for the pulse wave signal from the tonometer sensor 2 to be reliable, there is a person to be measured who desires a relatively high pressing force, and since the wrist is sensitive to the pressing force, it is relatively low. Some people demand pressing force.

Preferably, the pressing force of the tonometer sensor 2 is adjusted only by the elastic force of the spring 4, but in that case, since the size and shape of the wrist vary depending on the living body, an appropriate shape for each living body is obtained. It is necessary to prepare the spring 4 of. However, normally, (a), (b), and (c) in FIG.
As shown in, three types of springs with different shapes 4
A, 4b, 4c can correspond to most living bodies. Of FIG.
The springs 4a, 4b, and 4c of (a) to (c) have a length and a bending degree that are applicable to a standard living body. The springs 4a, 4b and 4c differ only in their radius of curvature.

The pulse rate measurement by the above pulse rate measuring apparatus will be described below. To understand this, first, the important features of the standard pulse wave waveform will be described.

A standard pulse wave 100 is shown in FIG. 11 along with its average pulse pressure 102. In this standard pulse wave 100, the upper peak point 104 showing the highest pulse pressure shows the time point of systole, and the lower peak point 106 showing the lowest pulse pressure shows the time point of diastole. Standard pulse wave 1 by scientific analysis
The point having the maximum inclination angle at 00 is the lower peak point 106.
It has been found that it exists within the boosting section 108 from the upper peak point 104 to immediately before the upper peak point 104. The notch 110 is present in a considerable number of biological pulse wave waveforms.

An inverted pulse wave 100 'is shown in FIG. The inversion pulse wave 100 ′ is generated when the sensor element 15 itself is arranged outside the normal position on the artery even if the case 3 is normally positioned on the artery. In this case, the pulse pressure due to the pulsation of the living body directly acts on the case 3, while the pulse pressure acting on the sensor element 15 is reduced. As a result, although the pulse wave is sampled, the waveform is inverted up and down, and shows a relatively negative pressure. The inversion pulse wave 100 ′ is applied to the lower peak point 104 ′ corresponding to the upper peak point 104 which is the time point of the systole, the upper peak point 106 ′ corresponding to the lower peak point 106 which is the time point of the diastole, and the boost section 108. Corresponding step-down section 10
8'and a notch 110 '.

The calculation of the pulse rate is performed in the electronic circuit shown in FIG. 4 housed in the case 3 according to the flowcharts of FIGS.

First, as apparent from FIG. 4, in the present embodiment, the circuit for calculating the pulse rate by processing the output signal of the tonometer sensor 2 includes a preamplifier 58, a high-pass filter 60 and a low-pass filter 62. , Amplifier 64,
A / D converter 66, CPU 68, RAM 70, ROM 7
2, I / O interface circuit 74 and display device 7
It is composed of six. As shown in FIG. 4, the preamplifier 58, the filters 60 and 62, the amplifier 64, and the A / D converter 66 include the tonometer sensor 2.
A plurality of output signals from the plurality of sensor elements 15 constituting the above are respectively supplied.

In operation, the plurality of pulse wave signals corresponding to the output signals of the plurality of sensor elements 15 of the tonometer sensor 2 are all supplied to the preamplifier 58. In this preamplifier 58, the signal is amplified before being filtered. The output signal of the preamplifier 58 is a high pass filter 60.
The DC component and extremely low frequency component are removed by being supplied to. The signal output from the high pass filter 60 is supplied to the low pass filter 62, where a predetermined high frequency component is removed. That is, the high-pass filter 60 and the low-pass filter 62 substantially function as a band-pass filter by using them together. The preferred band of this virtual bandpass filter 60 and 62 is about 0.1-30 Hz.
Is. The pulse wave signal that has been subjected to the above filter processing is amplified by the amplifier 64 to a level compatible with the A / D converter 66, converted into a digital signal by the A / D converter 66, and then the I / O interface. It is supplied to the circuit 74.
The digital signal supplied to the I / O interface circuit 74 is read by the CPU 68, and the RAM 70 is read.
Memorized in.

The RAM 70 is composed of a plurality of data buffers and stores a plurality of types of digital signals corresponding to a plurality of pulse wave signals from a plurality of sensor elements 15.
The ROM 72 holds control program software used by the CPU. The CPU 68 inputs the digital signal from the A / D converter 66 via the I / O interface circuit 74 and supplies a signal indicating the pulse rate calculated based on this signal to the display device 76.

The operation of the CPU 68 will be described below with reference to the flow charts shown in FIGS.

When the pulse rate measuring device is activated or reset by the person to be measured, an initialization routine is executed and the stored data is reset. Further, a clock (not shown) is operated and the clock signal is supplied to the CPU 68, so that the device is set to operate for a predetermined sampling period.

In the program segment 1 of the program shown in FIG. 5, it is determined in sub-step 1a whether or not the operation of the clock is started. When it is determined in 1a that the clock operation is not yet started, this cycle is executed again. If it is determined that the clock is running, the CPU
Substep 1b is executed under the control of 68, and a plurality of types of pulse wave signals from the plurality of sensor elements 15 of the tonometer sensor 2 are read. Further, after the system timers are updated, the program segment 2 is executed.

In the program segment 2 corresponding to the excessive pulse wave signal removing means of the present invention, the sensor element 1 is used.
For each of the pulse wave signals from 5, it is determined whether the data exceeds a predetermined upper limit value. If the value indicated by the actually obtained data exceeds the upper limit value, that is, the maximum amplitude determined in advance, the data is set to zero. Further, in segment 2, by setting a predetermined flag, all the data exceeding the maximum value in the next 5 seconds are set to zero. In this way, noise is removed by eliminating a signal having a large amplitude that exceeds the amplitude of a normal pulse wave signal.

In the segment 3, the differential processing signal is obtained by performing the differential processing on the pulse wave signal. That is, in the sub-step 3a corresponding to the weighted average signal calculating means of the present invention, a plurality of types of pulse wave signals from the sensor elements 15 which are not set to zero in the program segment 2 are all averaged to thereby obtain a predetermined value. A weighted average signal is calculated based on the weighting coefficient of. The weighting factor used in the averaging process is preferably about 1.0, but can be modified as described below. Next, in sub-step 3b corresponding to the pulse wave signal correcting means of the present invention, this weighted average signal is subtracted from each of the plurality of types of pulse wave signals other than zero.

With such a difference processing algorithm,
Motion artifacts are removed from each pulse wave signal detected by the tonometer sensor 2. This algorithm is applied when a plurality of sensor elements 15 are used. The difference processing algorithm is effective for discriminating motion artifacts from true pulse wave signals corresponding to arterial pressure when a plurality of types of pulse wave signals are uniformly affected by motion artifacts. For example, motion artifacts that occur due to movements of a living body such as walking affect the sensor elements 15 to the same extent. On the other hand, the pulse wave signal that accurately reflects the arterial pressure acts only on the sensor element 15 located immediately above the artery or very close to it.

In the difference processing algorithm, the weighted average signal is determined based on the total of the plurality of types of pulse wave signals corresponding to the plurality of sensor elements 15. When the motion artifact acts evenly on the plurality of sensor elements 15, the weighted average signal accurately reflects the motion artifact. A difference processed signal is obtained by subtracting this weighted average signal from each pulse wave signal. (That is, each pulse wave signal is corrected by subtracting the signal accurately reflecting the motion artifact from each pulse wave signal.) The pulse wave signal before being corrected is a motion artifact signal. Even if
It is also considered to be a signal in which motion artifacts are added to the true pulse wave signal that accurately reflects the arterial pressure. FIG. 9 shows an example in which the difference processing algorithm is applied to the signals of three sensor arrays. Note that FIG.
The signal shown in is obtained in one clock tick.

The difference processing algorithm is one of the main components of this large algorithm. In this large algorithm, the output value of each processed signal corresponds to the weighted sum of the unprocessed signals. For example, the processed value of 1 is obtained by weighting the three unprocessed values and adding them as shown below.

[0043]

[Equation 1]

Within the technical scope disclosed as the present invention, processing other than Expression 1 may be further added in the segment 3, and the weighting coefficient may be a value based on the basic difference processing technology. For example, it may be different from the value normally used in the difference processing algorithm (that is, 1.0). For example, a single preselected sensor element 15 is used as a reference, and a large negative weighting coefficient is applied to the output signal of the sensor element 15 located at a large distance from the reference sensor element, or a sensor element close to the reference sensor element 15 is applied. Even if a large positive weighting factor is applied to 15,
A proper weighted average signal is obtained and the averaging process can be normally performed.

Returning to FIG. 5, the program segment 3
Then, the program segment 4 is executed, so that the difference processing signal is processed based on the correlation algorithm.

By the correlation algorithm, regarding the pulse wave waveforms for two consecutive beats sampled in a predetermined period so as to substantially correspond to two consecutive heart beats, two pulse wave waveforms corresponding to one beat are The similarity between them is quantitatively calculated.
The principle is that the pulse wave waveforms corresponding to the heartbeat of one beat in the human body and the heartbeat of the subsequent one beat are very similar. With the correlation algorithm, the waveform of the pulse wave generated in synchronization with the current heartbeat,
The waveform of the pulse wave detected in synchronization with the heartbeat immediately before that is compared.

The processing based on the correlation algorithm is executed as follows in substep 4a corresponding to the autocorrelation value calculating means and the autocorrelation determining means of the present invention. The variable ICOR is used as a counter to continuously measure the number of clock signals (tick) (ie elapsed time) spent until detecting the time of systole. ICOR is set to 1 at the start of processing. ICOR is then incremented by 1 corresponding to each increment of the clock tick. (That is, the time data is read one by one.) Variable IC
When OR is set to 1, the variable DSUM described later
And NSUM are set to zero. It is predetermined among the plurality of sensor elements 15 constituting the tonometer sensor 2 in the period from the start of the detection process of the cardiac contraction time to the actual (presumed) heart contraction time being detected. The data from a particular single sensor element 15 is stored in a data buffer called CORELA. The variable ICOR is used as a pointer for CORELA. That is, after the time measurement of ICOR corresponding to the tick of the clock is started, in other words, the detection process at the time of systole is started, the data from the specific single sensor element 15 is used as the pointer. It is stored in CORELA.

For example, of the data from the single sensor element 15 specified in advance, the pulse wave signal data corresponding to the previous heartbeat is stored in the COLERA, while the pulse wave signal corresponding to the latest heartbeat is stored. Data is assumed to be stored in a data buffer separate from CORELA called COLELB. When the current time point of systole is detected in synchronization with the latest heartbeat, the correlation coefficient COR is subsequently calculated. The correlation coefficient between the previous pulse wave and the current pulse wave is mathematically defined as shown in Equation 2.

[0049]

[Equation 2]

In the above equation 2 based on the summation method, "Σ"
Is the sum of data corresponding to the time J that has elapsed from the start of operation until the time point of systole is detected. If the pulse waveform synchronized with the current heartbeat is exactly the same as the pulse waveform synchronized with the previous heartbeat, CORELA is CORE.
In agreement with LB, the correlation coefficient COR is shown by 1. Further, if the correlation coefficient COR is a value that is far apart from 1, it cannot be said that the waveforms of the previous pulse wave and the current pulse wave substantially match, and at least one of the above two pulse waves is The waveform is distorted due to motion artifacts. The correlation coefficient COR that can be recognized as a true pulse wave effective for pulse rate measurement in this program is about 0.6-
Waveforms within the 2.0 range and exhibiting correlation coefficients outside this range are removed or discarded. Of course, unless departing from the gist of the technology disclosed herein,
The determination reference range for determining the true pulse wave of the correlation coefficient COR may be a numerical value other than the above.

As a usual mathematical definition of the above-mentioned correlation coefficient, the correlation coefficient is the above-mentioned CORELA and CORE.
2 subject to correlation processing as exemplified by LB
For two waveforms, it only applies if the length of time spent in forming each waveform is exactly the same. In other words, the mathematical formula 2 has a mathematical value only when the occurrence periods of the two heartbeats corresponding to the two waveforms are equal. In this embodiment,
Without being restricted by such mathematical restraint force, the correlation coefficient C can be obtained even if the occurrence periods of two heartbeats are not completely equal.
The OR is calculated. Equation 2 is very effective in detecting motion artifacts, even if it is used in situations where it can be mathematically inaccurate, because of the long duration of time in which the two waveforms are present. Even if the values do not match, they are effectively used.

Preferably, the CORELB mentioned as the data buffer is not used, and instead, the moving addition value NSUM of the numerator of Equation 2 and the moving addition value DSUM of the denominator of Equation 2 are the data from each sensor element 15. Will be updated each time. As an example, assuming that BP (ELEMENT) shown in Expression 3 is the pressure detected by the single sensor element 15 specified in advance at the predetermined time indicated by the variable ICOR, the updating process is given by Expression 3 This is performed in the order of 10, equation 20, and equation 30.

[0053]

[Equation 3] 10 DSUM = DSUM + (BP (ELEMENT) × BP (ELEMENT)) 20 NSUM = NSUM + BP (ELEMENT) × CORELA (ICOR) 30 CORELA (ICOR) = BP (ELEMENT)

The correlation coefficient is simply calculated as in Equation 4 after detection of the time point of systole.

[0054]

[Formula 4] COR = NSUM / DSUM

CORELA (I
COR) still contains the pulse pressure data associated with the previous heartbeat. Therefore, CORELA is updated in Expression 30 of Expression 3 for the calculation processing relating to the next heartbeat. The use of such a moving add value instead of the processing in the two data buffers of CORELA and CORELB in Equation 2 is advantageous in that the computer processing can be efficient and the storage device can be simply constructed. Although the correlation coefficient COR is defined as in Expression 2, it may be defined in addition to Expression 2 as long as it does not depart from the gist of the technique disclosed herein.

In the table shown in FIG. 10, as an example, appropriate variables based on virtual data are described. Variable I
Assuming that the time when the COR shows 3 is the systolic time point (actually, a long pulse waveform is so long that much more data than 3 is obtained before the systolic time point is detected. The correlation coefficient COR (formed) is calculated as shown in Equation 5.

[0057]

COR = NSUM / DSUM = 3850/5325 =. 723 L Feed

The pulse wave signal is judged to be a true pulse wave signal effective for pulse rate measurement based on the judgment reference range of the correlation coefficient COR of 0.6 to 2.0.

Further, as another aspect regarding the calculation of the correlation coefficient COR, the definition of the following mathematical expression 6 can be given.

[0060]

## EQU6 ## COR = (CORELA (j) ^* CORELB (j) / (AMPA) × (AMPB)

However, AMPA = sqrt (DS in Equation 6
UM), AMPB = sqrt (DSUM ') (DSU
M'is DSUM) corresponding to the previous heartbeat.

Correlation coefficient COR defined as above
Is irrelevant to the change in magnitude that occurs between the two pulse wave signals corresponding to the current heartbeat and the previous heartbeat.

Substep 4b following substep 4a
Then, it is determined whether or not a period from the time of systole to a notch of about 0.25 seconds has elapsed within a predetermined standard period. When this determination is affirmed, the program segment 1 is executed again, and the pulse wave signal from the sensor element 15 is further read and accumulated. When the above determination is denied, the program segment 5 is subsequently executed.

As shown in FIG. 11, the non-inverted standard pulse wave waveform 100 has a relatively low step-down slope having an apex at the upper peak point 104 corresponding to the time point of systole and hanging downward. Exists extensively. Further, in this connection, the notch 110 showing the minimum pressure in a certain section is also clearly confirmed. Due to such characteristics, in the course of the program processing, the inverted waveform 100 ′ (that is, the waveform including the portion showing the minimum value in a certain section having a relatively wide range of step-down slope) despite being the standard pulse wave 100 is obtained. It may be erroneously determined to be present. A similar problem may occur in the inverted pulse wave 100 '.
That is, as shown in FIG. 12, an inverted pulse wave 100 ′ having a notch 110 ′ that appears following the time of systole,
It may be erroneously determined to be the newly generated standard pulse wave 100. As a program, the above standard pulse wave 100
Accurate processing of both the reverse pulse wave 100 'and the reverse pulse wave 100' is required. The best way to meet this requirement is to delay the start of the correlation processing of the pulse waveform, which usually occurs after the systolic time point is detected. However, this method has some drawbacks with respect to the correlation algorithm. This is because the correlation algorithm is most effective when executed immediately in response to the completion of the interval in which the pulse waveform has been formed to the shape to which the correlation algorithm can be applied. An eclectic solution considering the above inconvenience is to provide a predetermined delay period from the time when the systolic time point is detected in sub-step 4b to the start of the detection process of the next systolic time point, and this delay time period is set. That is, the correlation processing is started and completed in the period from when the program segment 5 has passed and before the program segment 5 is executed.

As described above, in the present embodiment, the positional relationship between the sensor element 15 and the artery is not set appropriately in the sub-step 4b corresponding to the auto-correlation processing delay means of the present invention, or the sensor element 15 is used. Since the inverted pulse wave 100 ′ generated due to the shift of the positional relationship with the living body is appropriately processed,
Various restrictions on wearing of the pulse rate measuring device and / or discomfort to the person to be measured are preferably eliminated as compared with a conventional pulse wave detecting device that can accurately process only a positive pressure waveform. .. The above-mentioned conventional pulse rate measuring device is required to be accurately arranged and relatively strongly held at a suitable position on the artery from which the pulse wave is to be collected, and various pulse rate measuring device mounting methods are required. It was unavoidable that constraints and / or discomfort to the person being measured.

In the program segment 5 which is executed subsequent to the program segment 4, among the pulse wave signals, signals having data showing the minimum value and the maximum value are accumulated and stored. As shown in FIG. 5, in sub-step 5a, the latest pulse wave signal data is compared with the previous pulse wave signal data, so that the predetermined pulse wave signal of the specific sensor element 15 is determined. It is determined whether it has increased, decreased, or equalized over time. If it is determined that the pulse wave signal has increased over time, sub-step 5
In e, the content of the flag DOWNHILL is False
It is said that. On the other hand, if it is determined that the flag has decreased, the content of the flag DOWNHILL is T in substep 5b.
rue. The pulse wave signals determined to have increased are processed in substeps 5e, 5f and 5g, and the signals determined to have decreased are processed in substeps 5b, 5c and 5d. Then, the program moves to segment 6.

In FIG. 6, in substep 6a corresponding to the gradient value calculating means of the present invention, the gradient value of the pulse wave signal corresponding to the specific sensor element 15 is calculated. Subsequently, in the sub-step 6b corresponding to the inclination determining means of the present invention, it is judged whether or not the inclination value obtained in the sub-step 6a exceeds a predetermined threshold inclination value. After (although it is not clear whether it is true) is detected, it is determined whether a pulse wave signal having a slope above a predetermined threshold slope value has already occurred. If it is determined that a pulse wave signal with a slope exceeding the threshold slope value has already been generated since the previous systole time was detected, the next maximum systole time is detected by detecting the next maximum systole time. Sub-steps 6e-6i for detecting? Substep 6e
When the systolic time point is detected as the upper peak point 104 showing the maximum value in the standard pulse wave and the lower peak point 104 'showing the minimum value in the inverted pulse wave, sub-step 6g is executed. A value corresponding to 65% of the maximum absolute slope value is stored and used as the threshold slope value for the next signal. Above peak point 104 or below peak point 1
If 04 'is not detected, the segment 13 of FIG.
Is executed, the program segment 1 is returned to. If it is determined in sub-step 6b that a pulse wave signal exceeding the threshold slope value has not been generated after the detection of the previous time point of systole, sub-steps 6j to 6p are executed, so that It is determined whether or not a pulse wave signal having a slope value exceeding the threshold slope value is generated within a preset sampling period as a detection period at the time of cardiac contraction. In sub-step 6m, it is determined whether or not the absolute value of the current inclination is larger than the threshold inclination value. If it is determined that the absolute value of the current inclination is larger than the threshold inclination value, sub-step 6o is executed. If the determined slope value is negative, the inverted pulse wave 10
The flag is set to the content indicating 0 '. Subsequent execution of substep 6p and program segment 13 causes the program to return to segment 1 for further data storage.

If in the program segment 6 what is determined as the systole time (it is not certain whether this is true or not) is detected by the substeps 6e and 6f corresponding to the systole time detection means of the present invention, it continues. In the program segment 7, the pulse wave signal having the maximum amplitude among the plurality of sensor elements 15 and the sensor element 15 that has output the maximum pulse wave signal are specified. The amplitude of the pulse wave signal is, in one sensor element 15, the maximum value (maximum value) and the minimum value (minimum value) of the pulse wave signal output from the sensor element 15 in synchronization with one heartbeat. It is measured based on the difference between. In sub-step 7a of FIG. 7, the pulse wave signal having the maximum amplitude and the sensor element 15 corresponding thereto are identified from the plurality of pulse wave signals corresponding to the plurality of sensor elements 15. In sub-step 7b, the pulse wave signal having the maximum positive amplitude and the sensor element 15 corresponding to the pulse wave signal are identified from the plurality of pulse wave signals. In sub-step 7c, the index corresponding to the pulse wave signal having the largest amplitude in each heartbeat is sequentially stored, so that the maximum amplitude is shown over the continuous five heartbeats including the latest heartbeat. The sensor element 15 that outputs the pulse wave signal is selected as the virtual sensor element 15 (active element) that is reliable.

The program segment 8 is a program for inspecting two triggers (maximum values) included in the generation period of one pulse wave, and corresponds to the systole cycle determining means of the present invention. First, in sub-steps 8a and 8c, it is determined whether or not the systolic cycle from the previous systolic time to the present systolic time is within ± 30% of the previously determined average systolic cycle. It If this determination is positive, some steps are omitted and sub-step 8e is immediately executed, and the cardiac contraction cycle is stored in the RAM 70. When the systolic cycle is less than or equal to -30% of the average systolic cycle, sub-step 8b is executed to detect a true pulse wave signal effective for pulse rate measurement in the past 15 seconds, which is the reverse of the present. Whether or not it is determined. When the true pulse wave signal is not detected, the above-mentioned sub-step 8e is executed. When it is determined that the true pulse wave signal is detected within 15 seconds, the substeps 8c and 2 trigger algorithm processing are subsequently executed.

The two-trigger algorithm is for handling unwanted triggers that occur between two valid triggers. The name is based on the fact that two triggers are more likely to occur than one trigger in relation to a pulse wave signal of one beat.

The two-trigger algorithm uses the latest systolic cycle (in this program, this latest systolic cycle is referred to as the variable SYSTIM) as the latest systolic cycle among the systolic cycles corresponding to the period connecting two consecutive systole points. , And a predetermined reference cycle range whose core is an average systolic cycle determined in advance based on a weighted average pulse rate described later. In the 2-trigger algorithm, both the latest systolic cycle and the previous systolic cycle (both are unknown whether or not the cycle is an effective cycle based on a true pulse wave signal effective for pulse rate measurement) are sequentially stored. . In this program, the previous systolic cycle is called the variable SYS1.

According to the processing of program segment 8,
If the latest systolic cycle exceeds 70% of the predetermined average systolic cycle, then segment 8
No processing is added to the two-trigger algorithm. When it is determined that the pulse rate is 70% or less of the average systolic cycle, it is determined whether or not a true pulse wave signal effective for pulse rate measurement is detected within 15 seconds, which is a rise from the present. If this determination is denied, the two-trigger algorithm processing is not performed and the next processing is performed.

When it is determined that the true pulse wave signal has been detected within the last 15 seconds, the total value of the current systole cycle and the previous systole cycle is compared with the average systole cycle. When this total value is less than 130% of the average systole cycle, the variable SYSTIM is updated to SYSTIM + SYS1.

As described above, in this embodiment, since the two algorithms are implemented in the program segment 8, the erroneous measurement of the pulse rate due to the notch is preferably compensated for, and the accuracy of the pulse rate measurement is improved. The decrease can be suitably prevented. Conventionally, if the pulse wave signal has a notch,
During each cycle of the heartbeat, the pressure rising period and the pressure reducing period are confirmed twice, and one pulse is erroneously determined to be two beats in relation to these two pressure rising periods and pressure reducing periods. In some cases, such an inaccurate judgment was a factor that significantly deteriorated the measurement accuracy of the pulse rate.

In the two-trigger algorithm, even when the actual systolic cycle is divided into two as the previous systolic cycle and the present systolic cycle due to the mixing of short-term noise signals or motion artifacts appearing as a protruding waveform, This condition is compensated.
The current systole cycle is compensated, and this compensated systole cycle is set as the previous systole cycle for the heartbeat expected to occur next time. The two-trigger algorithm is a principle that can process three or more triggers for one heartbeat.

The two-trigger algorithm in this embodiment is concerned only with the weighted average pulse rate and has no effect on the above-mentioned correlation algorithm. However, according to another preferred embodiment of the present invention, the signal processing can be performed while the following conditions are satisfied and the two-trigger algorithm and the correlation algorithm are correlated with each other.

1. The variable ICOR is not reset if the trigger occurs within an abnormally short period of time that is predetermined based on the weighted average pulse rate. 2. In order to prevent the occurrence of a trigger that should not originally exist in the upslope portion adjacent to the notch,
The start of the detection process of the trigger performed after the time point of systole is detected is delayed. During this delay period, the correlation process, that is, the above-mentioned array CORERA, variable N
The processing operations in which SUM, DSUM and ICOR are each updated in relation to the clock measurement continue.

An important point in implementing the two-trigger algorithm is to limit its use. In particular, the processing related to the two-trigger algorithm is not executed after 15 seconds or more have passed since the true pulse wave effective for pulse rate measurement was detected. Also, it should not be used when starting the program of this embodiment. Once a true pulse wave useful for pulse rate measurement is detected, the two-trigger algorithm acts to help detect the true pulse wave.
Then, 15 seconds after the true pulse wave is detected, the two-trigger algorithm process is stopped, so that the “generation” of the pulse wave that should not actually exist is suppressed. The weighted average pulse rate tends to shift during periods of strong noise and artifacts. If the total time of occurrence of a plurality of pulses that should not be present is, for example, 15 seconds or more, the possibility of deviation of the pulse rate may reach 50% of the actual pulse rate. At this time, if the processing of the two-trigger algorithm is still valid, a shift of up to 50% of the actual pulse rate can be prevented. Based on the principle of 2 trigger algorithm, 1/2 trigger algorithm,
It is wise to implement 1/3 trigger algorithm etc. The 1/2 trigger algorithm and 1/3 trigger algorithm are algorithms for compensating for a trigger that should exist if it is not collected.

Subsequently, the program moves to segment 9.
In this segment 9, it is determined whether or not the systolic cycle is within a predetermined range based on physiology, that is, within a range corresponding to about 35 to 225 beats / minute (BPM) in terms of pulse rate. To be done. When the systolic cycle is not within the above range, the program segment 14 is executed, and in the sub-step 14a, it is judged whether or not a true pulse wave effective for pulse rate measurement is detected in 30 seconds going up from the present. It When this true pulse wave is detected, the program segment 13 is executed and then the process returns to the segment 1. When the true pulse wave is not detected, the display device 76 is blank in the sub-step 14b.
After that, the segment 13 is executed, and then the process returns to the segment 1. When it is determined that the systolic cycle is within the predetermined range in the segment 9a, the program moves to the segment 10.

In the segment 10, the weighted average pulse rate is calculated and it is judged whether or not the weighted average pulse rate is within a predetermined range.

In sub-step 10, the weighted average pulse rate is calculated by equation (7).

[0082]

## EQU00007 ## APR _t = APR _t-1 × (1-C) + (PR _t ) × C

In Equation 7, APR _t is the current average pulse rate, APR _t-1 is the previous average pulse rate, PR _t is the current pulse rate, and C is the weighting coefficient of this time, which is the weighting coefficient in the previous processing step. It is a value that is less than the previous weighting coefficient calculated by the program segment 10.

In sub-step 10b, it is judged whether or not the weighted average pulse rate of this time is within a predetermined range of about 0.8P to 1.3P. Here, the P corresponds to the previous weighted average pulse rate. If the current weighted average pulse rate is within the above range, the program proceeds to substep 10c.
Then, the weighting coefficient C is reduced by a predetermined ratio of 0.1 or more, and the reduced weighting coefficient is stored as a new weighting coefficient C. The program then moves to segment 11. In the sub-step 10b, when it is determined that the weighted average pulse rate of this time is not within the range of 0.8P to 1.3P, the sub-step 10d is executed so that the weighting coefficient C is 0.5 or less in advance. The weighting factor is increased by a predetermined ratio, and the increased new weighting factor is stored. Then, after the artifact flag is set in step 10e, the above-described processing is executed in the program segment 14.

Turning to FIG. 8, the program segment 11
Then, it is determined whether the pulse wave signal from the segment 10 exceeds a predetermined threshold noise. The predetermined threshold noise value is, for example, 0.025.
The output signal of the sensor element 15 is about 0.7
Equivalent to mmHg. When it is determined that the pulse wave signal is smaller than the predetermined threshold noise value, the program segment 14 is executed after the artifact flag is set in sub-step 11b. If it is determined that the amplitude of the pulse wave signal exceeds the threshold noise value, segment 12 is executed.

In the program segment 12, the correlation coefficient COR is calculated according to equation 8 in sub-step 12a. Note that both NSUM and DSUM in Expression 8 are values calculated in the program segment 4.

[0087]

[Equation 8] COR = NSUM / DSUM

In sub-step 12b, the correlation coefficient COR
Is determined to be within a predetermined range, for example, the range of 0.6 to 2.0. If it is determined that the correlation coefficient COR is not within the above range, sub-step 12c
After the artifact flag is set at, the program segment 14 is executed. If it is determined that the correlation coefficient COR is within the above range, the program segment 13 is executed.

In program segment 13, the pulse rate is calculated and displayed. In sub-step 13a, the pulse rate to be displayed, that is, the weighted average pulse rate based on the true pulse wave signal effective for pulse rate measurement is calculated as the display pulse rate. The displayed pulse rate is not the same as the weighted average pulse rate calculated in program segment 10, and the displayed pulse rate is updated only in connection with the detection of the true pulse wave. When the true pulse wave is detected, the displayed pulse rate is calculated according to the equation (9).

[0090]

## EQU9 ## DPR _t = (1-D) × (DPR _t-1 ) +
(D) x (PR _t )

In Equation 9, DPR _t is the latest displayed pulse rate corresponding to the updated contents, DPR _t-1 is the previous displayed pulse rate, PR _t is the latest pulse rate, and D is a constant. The constant D is preferably a predetermined value and is about 0.2.

In substep 13b, the delay period from the detection of the time point of systole to the start of the correlation processing is 1
It is set to 0.25 times the heartbeat period of the beat, and in the subsequent substep 13c, the systole time detection timer is reset. In the subsequent substep 13d, the contents of the display device 76 are updated. And the program goes back to segment 1,
The program for pulse rate measurement is repeatedly executed.
That is, the sub-step 13a constitutes the pulse wave number calculation means of the present invention, and the sub-step 13d constitutes the display means of the present invention together with the display device 76.

As described above, in the pulse rate measuring apparatus of this embodiment, in the sub-step 3a of the program segment 3, the weighting coefficient determined in advance from the plurality of types of pulse wave signals corresponding to the plurality of sensor elements 15 is used. The weighted average signal calculated based on the above is subtracted from each of the plurality of types of pulse wave signals in sub-step 3b to correct the plurality of types of pulse wave signals. Then, the pulse rate is calculated based on the corrected pulse wave signal in the program segment 13a, and the pulse rate is displayed on the display device 76 in the program segment 13d. Therefore, according to the apparatus of the present embodiment, obtained by subtracting the weighted average signal of the plurality of types of pulse wave signals that accurately reflect the motion artifacts from each pulse wave signal, substantially the motion artifacts. Since the pulse rate is calculated from the corrected pulse wave signal that has been removed, artifacts such as motion artifacts are preferably compensated for, and high reliability of the pulse rate is obtained.

Furthermore, in this embodiment, since a plurality of algorithms are used in combination as means for removing motion artifacts, a plurality of different motion artifacts occur at the same time, and
In addition, it is possible to obtain a highly accurate pulse even if a phenomenon that cannot be dealt with by one means of obtaining the accuracy of signal processing occurs. By implementing at least one of the plurality of algorithms disclosed in the present embodiment, it is possible to obtain a tentative effect on the measurement accuracy of the pulse rate.

Those skilled in the art will appreciate other embodiments of the invention other than those described above. For example, although the pulse wave number measuring apparatus is disclosed in the present embodiment, the apparatus shown in FIGS. 1 to 4 can also be applied as an apparatus for measuring parameters related to cardiopulmonary function such as blood pressure or respiratory rate. The pulse rate measuring apparatus of the present embodiment is characterized in that it has an effect that motion artifacts and noise artifacts are removed or compensated, and an effect equivalent to this is a measurement that has a detection function of pulse pressure or pulse wave. Enjoyed by the device. ROM based on the pulse rate measuring device of the present embodiment
By changing the program stored in 72, it is possible to obtain a plurality of measuring devices for measuring parameters relating to the heart or lungs.

The program segments shown in FIGS. 5 to 8 can be added or partially changed. For example, in the present embodiment, only the 2-trigger algorithm is implemented, but as described above, the 1/2 trigger algorithm or the 1/3 trigger algorithm may be additionally executed.

Further, the constant (weighting coefficient) C used in the program segment 10 may be another value. There are a plurality of algorithms for determining the weighting coefficient C used in the process of calculating the weighted average pulse rate, other than the algorithm disclosed as the present embodiment. However, with respect to all the weighting factor algorithms of this embodiment and the other weighting factor algorithms described below, the weighting factor C is about 10% to 50%.
It is limited to the range of%. (That is, the latest pulse rate is averaged by the weighted average pulse rate.
A weight limited to the range of ˜50% is given to the latest pulse rate. ) For example, in the first algorithm, the weighting coefficient C is given by K / (heart rate). The weighting coefficient C set in this way is inversely proportional to the heart rate. When the pulse rate per minute is 60, the proportional constant K is set so that the weighting coefficient C is 50%. The second algorithm is given by C = f (reliability; Belief). In this algorithm, when the latest pulse rate is included in the predetermined reference pulse rate range having the weighted average pulse rate as the core, the weighting coefficient C is set to 45%, and the latest pulse rate falls within the range of the reference pulse rate. If it exceeds, the weighting coefficient C is set to 15%. That is, in the second algorithm, the weighting coefficient C is set to a large value when the reliability indicating the accuracy of the latest pulse rate is high, and the weighting coefficient C is set to a low value when the reliability is low. Preferably, the reference pulse rate range is a range of 20% or less to 30% or more of the weighted average pulse wave number. The third algorithm is given by C = kX (DISTIM). In this algorithm, the weighting coefficient C is the elapsed time D from when the true pulse wave effective for pulse rate measurement is detected.
Proportional to ISTIM. The constant of proportionality k is a weighting coefficient C when about 15 seconds have passed since the detection of a valid true pulse wave last time.
Is set to about 50%.

A person skilled in the art can easily use the present invention in order to improve the circulation function by adding another feature to the present embodiment within the technical scope of the present invention. Be understood by. In order to make the circulatory function sound, it is effective to raise the pulse rate to a predetermined minimum level or higher and maintain this state for a predetermined minimum period. It is easy for a person skilled in the art to provide a notifying means for notifying when the displayed pulse rate is lower than the exercise pulse rate preset as the minimum level. In addition to such characteristics, a display unit for indicating the pulse rate over time may be added to show the actually performed total circulatory function exercise state. In this case, an alarm means may be provided which is activated after the heart rate is kept elevated for a predetermined period.

The present invention is also effective for a patient having a dysfunction of the circulatory system by providing an alarm means that operates when the displayed pulse rate exceeds a predetermined value. Can be applied.

Those skilled in the art will be able to recognize various modifications of the present invention from the above description in addition to the above.
Thus, although only a part of the embodiments is disclosed in the present specification, the present invention can be modified in many ways other than the above without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a pulse rate measuring apparatus having a pulse rate measuring sensor connected to a case according to an embodiment of the present invention.

FIG. 2 is a perspective view of a tonometer sensor held by a gimbal member.

FIG. 3 is a diagram showing the curvature of a spring of the tonometer sensor of FIG. 2, where a is a small curvature, b is a medium curvature,
c is the case where the degree of curvature is large.

FIG. 4 is a block diagram of a pulse rate measurement processing circuit in a pulse rate measuring apparatus according to a preferred embodiment of the present invention.

5 is a part of a flowchart illustrating the operation of FIG.

6 is a part of a flow chart illustrating the operation of FIG.

7 is a part of a flowchart illustrating the operation of FIG.

FIG. 8 is a part of a flowchart illustrating the operation of FIG.

FIG. 9 is a chart showing a result of processing an unprocessed signal by a difference processing algorithm in FIG. 5;

10 is a chart showing the correlation algorithm used in FIG.

FIG. 11 is a diagram showing a standard pulse wave waveform.

FIG. 12 is a diagram showing an inverted pulse wave waveform.

FIG. 13 is a diagram corresponding to the claims of the present invention.

[Explanation of symbols]

1: Pulse rate measuring device 2: Tonometer sensor 15: Sensor element 68: CPU 76: Display device (display means) Program segment 2: Excessive pulse wave signal removing means Substep 3a: Weighted average signal calculating means Substep 3b: Pulse Wave signal correction means Substep 4a: Autocorrelation value calculation means, autocorrelation determination means Substep 4b: Autocorrelation processing delay means Substep 6a: Inclination value calculation means Substep 6b: Inclination determination means Substeps 6e, 6f: Heart contraction Time point detection means Program segment 8: Cardiac contraction cycle determination means Program segment 13a: Pulse rate calculation means Program segment 13d: Display means

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Stephen T. Houms California 94306 Palo Alto Mabel Way 4144 (72) Inventor Thomas Pie Law United States California 94062 Woodside Skywood Way 60 (72) Inventor Rudolf Erbrecht United States California 94022 Los Altos Ferndan Avenue 1888 (72) Inventor Philipp Earl Juke the Sard United States California 94028 Menlow Park Diana Drive 1150 (72) Inventor Ronald E. Pelllein, California 94028 Menlo Park Row Ray's Avenyu number 3 689- Bee (no address) (72) inventor Victor tea Newton junior United States, California 94025 Menrou Park Waverley Street Number 4 307

Claims (6)

[Claims] 1. A tonometer sensor having a single array composed of a plurality of sensor elements, wherein a highly accurate pulse rate is obtained based on a plurality of types of pulse wave signals output from the tonometer sensor. And a weighted average signal calculation means for calculating a weighted average signal of the plurality of types of pulse wave signals based on a predetermined weighting coefficient, and a weighted average signal calculation means for calculating the weighted average signal. A pulse wave signal correcting unit that corrects the plurality of types of pulse wave signals by subtracting an average signal from each of the plurality of types of pulse wave signals, and a corrected pulse wave signal that is corrected by the pulse wave signal correcting unit. A pulse rate measuring device comprising: a pulse rate calculating means for calculating a pulse rate according to the present invention; and a display means for displaying the pulse rate calculated by the pulse rate calculating means. 2. An autocorrelation value calculation means for calculating an autocorrelation value indicating an autocorrelation degree within a predetermined period in at least one of the plurality of types of corrected pulse wave signals, wherein the pulse rate measuring device comprises: An autocorrelation determining unit that determines that the corrected pulse wave signal is valid because the autocorrelation value calculated by the autocorrelation value calculating unit is within a range of a predetermined correlation coefficient. The pulse rate measuring device according to 1. 3. The pulse rate measuring device, a slope value calculating means for calculating a slope value in at least one of the plurality of types of corrected pulse wave signals, and the slope value calculated by the slope value calculating means in advance. The pulse rate measuring device according to any one of claims 1 and 2, further comprising: a slope determining unit that determines that the corrected pulse wave signal is valid because it exceeds a predetermined threshold slope value. 4. The heart rate measuring device detects a heart contraction time point in at least one of the plurality of kinds of corrected pulse wave signals, and a heart contraction time point detected by the heart contraction time point detecting means. The cardiac contraction cycle, which is the time interval at the time point, is compared with a predetermined reference cycle, and when the cardiac contraction cycle exceeds the reference cycle, the cardiac contraction cycle is determined as the current cardiac contraction cycle, When the systolic cycle is less than or equal to a predetermined range, a systolic cycle determining means for determining the current systolic cycle based on the total value of the systolic cycle and the previously determined systolic cycle, The pulse rate measurement device according to claim 1, further comprising: 5. The pulse rate measuring device determines, in at least one of the plurality of types of pulse wave signals, a pulse wave signal that exceeds a predetermined upper limit value as an artifact signal and removes the artifact signal. The pulse rate measuring device according to claim 1, further comprising an excessive pulse wave signal removing means. 6. The pulse wave number measuring apparatus according to claim 2, further comprising an autocorrelation processing delay means for operating the autocorrelation value calculation means and the autocorrelation determination means after a predetermined period from the time of systole. Pulse rate measuring device.