JP2019097735A - Signal processing device, pulse analyzing device, signal processing method and program - Google Patents

Abstract

To generate a signal in which influence from body motion is reduced.SOLUTION: A signal processing device includes a signal processing unit for the more emphasizing a part the smaller the part with intensity of an envelope curve of a detection signal that indicates a temporal change of intensity of light that has passed through an organism.SELECTED DRAWING: Figure 3

Description

  The present invention relates to techniques for processing signals.

  Techniques for processing a signal according to the intensity of light passing through a living body have been conventionally proposed. For example, Patent Document 1 discloses a technique for generating envelope data used to calculate the blood oxygen saturation level of a subject from an electrical signal corresponding to the intensity of light passing through a living body. Envelope data is used to calculate blood oxygen saturation with a reduced error caused by the subject's body movement.

JP 2012-24320 A

  However, with the technique of Patent Document 1, it is not always possible to calculate blood oxygen saturation with high accuracy by sufficiently reducing an error caused by body movement. In consideration of the above circumstances, a preferred embodiment of the present invention aims to generate a signal in which the influence of body movement is reduced.

  In order to solve the above problems, a signal processing device according to a preferred aspect of the present invention is a portion of a detection signal representing a temporal change in the intensity of light passing through a living body, where the intensity of the envelope of the detection signal is small. Emphasize. The strength of the envelope in the portion where body movement occurs in the detection signal is higher than the strength in the portion where there is no body movement. In the above aspect, of the detection signal representing the temporal change in the intensity of light having passed through the living body, the smaller the intensity of the envelope of the detection signal is emphasized, the signal with reduced influence of body movement is generated. be able to.

  In a preferred aspect of the present invention, the signal processing unit includes an envelope generation unit that generates the envelope of the detection signal, and a suppression coefficient A (A>) by multiplying the strength of the envelope by γ (γ> 1). It includes an arithmetic processing unit that calculates a correction value by multiplying by 1), and a division unit that divides the intensity of the detection signal by the correction value. In the above aspect, since the strength of the detection signal is divided by the correction value calculated by multiplying the strength of the envelope by the power of γ and multiplying by the suppression coefficient A, a signal in which the influence of body movement is reduced is generated. be able to.

  In a preferred aspect of the present invention, the envelope generation unit generates a time series of movement maximum values of the detection signal as the envelope. In the above aspect, since the time series of the movement maximum value of the detection signal is generated as the envelope, the processing load of the signal processing device is reduced as compared with the configuration in which the envelope is generated by Hilbert transform, for example.

  In a preferred aspect of the present invention, the envelope generation unit includes a full wave rectification circuit for full wave rectification of the detection signal, and a smoothing circuit for smoothing the signal after the full wave rectification. In the above aspect, the envelope is identified by performing full-wave rectification on the detection signal and smoothing the full-wave rectified signal, so, for example, in comparison with a configuration that generates an envelope by Hilbert transform, The processing load of the signal processing device is reduced.

A pulse analysis device according to a preferred aspect of the present invention is a signal processing unit that emphasizes a portion of a detection signal representing a temporal change in the intensity of light having passed through a living body, the smaller the intensity of the envelope of the detection signal.
The signal processing unit includes a conversion unit that converts a signal processed by the signal processing unit into a frequency spectrum, and a pulse identification unit that identifies the pulse rate of the living body from the frequency of a peak at which the intensity is maximum among the frequency spectrum. The strength of the winding wire at the portion where body movement occurs in the detection signal is higher than the strength at the portion without body movement. In the above aspect, of the detection signal representing the temporal change in the intensity of light having passed through the living body, the smaller the intensity of the envelope of the detection signal is emphasized, the signal with reduced influence of body movement is generated. be able to. In addition, since the pulse rate of the living body is identified from the signal processed by the signal processing unit, the pulse rate of the living body can be identified with high accuracy even when body movement occurs.

  A signal processing method according to a preferred aspect of the present invention emphasizes a portion of a detection signal representing a temporal change in intensity of light having passed through a living body, in a portion where the intensity of the envelope of the detection signal is small.

  A program according to a preferred aspect of the present invention causes a computer to function as a signal processing unit that emphasizes the smaller the intensity of the envelope of the detection signal in the detection signal representing the temporal change in the intensity of light passing through the living body. .

It is a side view of a pulse analysis device concerning a 1st embodiment of the present invention. It is the block diagram which paid its attention to the function of a pulse analysis device. It is a block diagram of a signal processing part. It is a graph which shows the detection signal which the pre-processing part generated. It is a graph which shows the envelope which the envelope production | generation part produced | generated. It is a graph which shows the correction | amendment envelope which the arithmetic processing part produced | generated. It is a graph which shows the detection signal which the signal processing part generated. It is a graph which shows the frequency spectrum which the conversion part generated. It is a flowchart of the process which a control apparatus performs. It is a graph which shows the detection signal in which the influence of body movement is included. It is a graph which shows the frequency spectrum produced | generated from the detection signal of FIG. It is a graph which shows the detection signal generated by amendment processing. It is a graph which shows the frequency spectrum produced | generated from the detection signal of FIG. 15 is a graph showing a detection signal generated when both the coefficient γ and the suppression coefficient A are set to 1. FIG. It is a graph which shows the detection signal produced | generated when coefficient (gamma) is set to one. It is a graph which shows the detection signal produced | generated when the suppression coefficient A is set to one. It is a graph which shows the frequency spectrum produced | generated from the detection signal of FIGS. 14-16. It is a block diagram of the signal processing part which concerns on 2nd Embodiment. It is a circuit diagram of an envelope generation part. It is a schematic diagram which shows the usage example of the pulse-analysis apparatus based on 3rd Embodiment. It is a schematic diagram which shows the other usage example of the pulse-analysis apparatus based on 3rd Embodiment. It is a block diagram of the pulse-analysis apparatus in a modification. It is a block diagram of the pulse-analysis apparatus in a modification. It is a block diagram of the pulse-analysis apparatus in a modification.

First Embodiment
FIG. 1 is a side view of a pulse analysis device 100 according to a first embodiment of the present invention. The pulse analysis device 100 is a measurement device that non-invasively measures the pulse rate (the number of beats per minute) of a subject. The pulse analysis device 100 is attached to a specific region (hereinafter referred to as “measurement region”) H of the subject's body. For example, the wrist and the upper arm are illustrated as the measurement site H.

  The pulse analysis device 100 is attached to the measurement site H. The pulse analysis device 100 according to the first embodiment is, as illustrated in FIG. 1, a wristwatch-type portable device including a housing 12 and a belt 14. The pulse analysis device 100 is attached to the subject's body by winding the belt 14 around the measurement site H.

  FIG. 2 is an electrical block diagram of the pulse analysis device 100. As shown in FIG. The pulse analysis device 100 includes a detection device 30, a control device 22, and a display device 23. The control device 22 is installed inside the housing 12. The display device 23 (for example, a liquid crystal display panel) is installed, for example, on the surface of the housing 12 opposite to the measurement site H, as illustrated in FIG. The display device 23 displays various images including the measurement result under the control of the control device 22.

  The detection device 30 is an optical sensor module that generates a detection signal Za according to the state of the measurement site H. As illustrated in FIG. 2, the detection device 30 according to the first embodiment includes a light emitting unit 31, a light receiving unit 32, a drive circuit 33, and an A / D converter 34. The light emitting unit 31 and the light receiving unit 32 are installed, for example, at a position facing the measurement site H in the housing unit 12. Note that one or both of the drive circuit 33 and the A / D converter 34 may be installed as an external circuit separate from the detection device 30.

  The light emitting unit 31 is a light source for irradiating the measurement site H with light. In the light emitting unit 31 of the first embodiment, for example, a light emitting element such as a light emitting diode (LED) that emits incoherent light is suitably used as the light emitting unit 31. The drive circuit 33 causes the light emitting unit 31 to emit light. In addition, you may utilize the several light emission part 31 which radiate | emits the light of a mutually different wavelength.

  The light incident on the measurement site H from the light emitting unit 31 passes through the inside of the measurement site H, repeats diffuse reflection, and exits the living body. Specifically, light passing through a blood vessel such as an artery (for example, the brachial artery, radial artery or ulnar artery) present inside the measurement site H and the blood in the blood vessel are emitted from the measurement site H.

  The light receiving unit 32 receives light coming from the measurement site H. The light receiving unit 32 according to the first embodiment generates a detection signal representing a temporal change in the intensity of light arriving from the measurement site H (that is, a detection signal representing a temporal change in the intensity of light passing through the living body) Za ′. For example, the light receiving unit 32 includes a light receiving element such as a photodiode (PD: Photo Diode) that generates a charge according to the light receiving intensity. The detection signal Za 'is an analog voltage signal according to the light reception intensity from the measurement site H. The blood vessels inside the measurement site H repeatedly expand and contract in a cycle equivalent to the pulsation, so that the detection signal Za ′ generated by the light receiver 32 according to the light reception level from the measurement site H is the measurement site H The pulse wave signal includes a periodic fluctuation component corresponding to the fluctuation of the blood flow volume of the blood vessel. That is, the detection signal Za 'includes a component representing a beat. The time length of the detection signal Za 'is preferably twice or more (for example, 16 seconds) of the expected beat cycle. As understood from the above description, the detection device 30 according to the first embodiment is a reflective optical sensor in which the light emitting unit 31 and the light receiving unit 32 are positioned on one side of the measurement site H. However, a transmission type optical sensor in which the light emitting unit 31 and the light receiving unit 32 are located on the opposite side of the measurement site H may be used as the detection device 30.

  The A / D converter 34 generates a digital detection signal Za from the analog detection signal Za 'generated by the light receiving unit 32. The detection signal Za is a digital signal corresponding to the intensity of light received by the light receiving unit 32. A case where the resolution of the A / D converter 34 of the first embodiment is 12 bits (4096 steps) is assumed for convenience. The resolution of the A / D converter 34 is arbitrary. The detection signal Za generated by the A / D converter 34 is supplied to the controller 22.

  The control device 22 is an arithmetic processing device such as a central processing unit (CPU) or a field-programmable gate array (FPGA), and controls the entire pulse analysis device 100. A configuration in which the functions of the control device 22 are distributed to a plurality of integrated circuits, or a configuration in which a part or all of the functions of the control device 22 are realized by dedicated electronic circuits may be employed. The control device 22 according to the first embodiment executes a program stored in a storage device (not shown) to perform a plurality of functions (signal processing for specifying a pulse rate from the detection signal Za generated by the detection device 30) The unit 221, the conversion unit 223, and the pulse identification unit 225) are realized. A part of the functions of the control device 22 may be realized by a dedicated electronic circuit.

  FIG. 3 is a block diagram of the signal processing unit 221. As shown in FIG. The signal processing unit 221 generates, from the detection signal Za generated by the A / D converter 34, a detection signal Ze in a time domain used to specify the pulse rate. The signal processing unit 221 of the first embodiment includes a preprocessing unit 81, an envelope generation unit 83, an arithmetic processing unit 85, and a dividing unit 87.

  The preprocessing unit 81 generates, from the detection signal Za generated by the A / D converter 34, a detection signal Zb in a time domain including a component representing a beat. FIG. 4 is a graph showing the detection signal Zb. Specifically, the preprocessing unit 81 extracts a component (for example, a component of a frequency band of 0.4 Hz to 4 Hz (24 bpm to 240 bpm)) representing a beat in the detection signal Za, and the intensity of the extracted component is minimum. The detection signal Zb is generated by normalizing the value to −1 and setting the maximum value to 1. For example, a band pass filter that passes a component of a specific frequency band is used to extract a component representing a beat. As illustrated in FIG. 4, the detection signal Zb may include, in addition to the periodic fluctuation component corresponding to the pulsation, a component resulting from the sudden body movement of the subject. There is a tendency that the intensity x of a portion (a section on the time axis) I where movement occurs in the detection signal Zb is larger than the intensity x of other portions. As understood from FIG. 4, the intensity x of the portion I of the detection signal Zb is larger than the intensities x of the other portions, so it is estimated that the body movement has occurred in the portion I. The detection signal Zb generated from the detection signal Za is a signal representing the intensity of light having passed through the living body (measurement site H), as with the detection signal Za.

  The envelope generation unit 83 in FIG. 3 generates an envelope Zc of the detection signal Zb generated by the preprocessing unit 81. FIG. 5 is a graph showing the envelope generated by the envelope generation unit 83. The envelope generation unit 83 of the first embodiment generates a time series of the movement maximum value of the detection signal Zb as an envelope Zc. Specifically, the envelope generation unit 83 specifies the maximum value (that is, the movement maximum value) of the strength of the detection signal Zb for each of a plurality of analysis periods moved by a predetermined time on the time axis. Identify the time series of maximum values as an envelope. The time length of the analysis period is, for example, equal to or less than the maximum cycle of pulsation (approximately 2.5 seconds) which can be assumed. Note that the time length of the analysis period may be set to a period equal to or less than the cycle corresponding to the latest pulse rate measured by the pulse analysis device 100. The intensity X of the envelope Zc (that is, the movement maximum value of the detection signal Zb) fluctuates in a range where the maximum value is 1.

The arithmetic processing unit 85 of FIG. 3 calculates the correction value V from the intensity of the envelope Zc generated by the envelope generation unit 83. The correction value V is a variable for correcting the detection signal Zb. FIG. 6 is a graph showing the time change of the correction value V (hereinafter referred to as “correction envelope”) Zd. A correction envelope Zd is generated by calculating the correction value V for each magnitude X of the envelope Zc. The correction value V is calculated by the following equation (1). That is, the correction value V is calculated by multiplying the strength X of the envelope Zc by γ (γ> 1) and multiplying by the suppression coefficient A (A> 1). The intensity X is subjected to gamma correction by raising the intensity X to the power of γ (X ^γ ). FIG. 6 shows the correction value V when the coefficient γ is set to 1.1441 and the suppression coefficient A is set to 3. The relationship between the coefficient γ and the suppression coefficient A will be described later. As understood from the equation (1), the correction value V becomes larger as the strength X of the envelope Zc becomes larger. That is, the correction envelope Zd is a signal in which the larger the strength X of the envelope Zc is, the more emphasized it is. Therefore, the intensity X of the envelope Zc of the portion I of the detection signal Zb where body movement has occurred is higher than the intensity X of the envelope Zc of the portion without body movement.

The divider 87 in FIG. 3 corrects the detection signal Zb generated by the pre-processor 81 using the correction value V. Specifically, the dividing unit 87 calculates the output value x ′ by correcting the intensity x of the detection signal Zb with the correction value V. The output value x 'is calculated by the following equation (2). Specifically, the output value x ′ is calculated by dividing the intensity x of the detection signal Zb by the correction value V. The output value x 'at the time is calculated by dividing the intensity x at an arbitrary time on the time axis of the detection signal Zb by the correction value V calculated from the intensity X at the time of the envelope Zc. Ru. The detection signal Ze of FIG. 7 is generated by performing the above-described operation for each of a plurality of different time points on the time axis. That is, the detection signal Ze is a signal representing a time change of the output value x ′.

The relationship between the suppression coefficient A and the coefficient γ will be described in detail below. As described above, since the resolution of the A / D converter 34 is 12 bits (4096 steps) and the detection signal Zb changes between the minimum value -1 and the maximum value +1, the intensity X of the envelope Zc is the minimum It is set to any numerical value of 4096 steps dividing the range from the value -1 to the maximum value +1. Assuming that the intensity X can be 0, the correction value V of equation (1) is 0 and equation (2) is division by zero. From the viewpoint of avoiding division by zero, in the first embodiment, the minimum value of the absolute value of the intensity X (that is, the intensity x of the detection signal Zb) is set to 1/2048. Assuming that the absolute value of the intensity X of the detection signal Zb and the absolute value of the intensity X of the envelope Zc become the minimum values (that is, the corrected output value x ′ becomes the maximum value), ) Is transformed into the following equation (2a).

さらに、Ａ／Ｄ変換器３４が出力する数値の最大値をＤmaxと表記すると、抑制係数Ａと係数γとの関係を規定する以下の数式（4）が導出される。なお、数式（4）における対数の底は任意である。

Equation (2a) is the maximum value of the output value x ′. When the equation (2a) is modified such that the maximum value becomes 1, the following equation (3) is derived.

Furthermore, if the maximum value of the numerical values output by the A / D converter 34 is expressed as Dmax, the following equation (4) defining the relationship between the suppression coefficient A and the coefficient γ is derived. In addition, the base of the logarithm in Formula (4) is arbitrary.

  When the suppression coefficient A is set to 3, the coefficient γ becomes 1.1441 by the calculation of the equation (4). As described above, since the coefficient γ and the suppression coefficient A are defined by the equation (4), the output value x ′ diverges to an excessive numerical value even when the intensity X of the envelope Zc is a sufficiently small numerical value. Can be prevented. The output value x ′ of the first embodiment fluctuates in a range where the minimum value is −1 and the maximum value is 1.

  As described above, the correction value V increases as the intensity X of the envelope Zc of the detection signal Zb increases. Therefore, the detection signal Ze representing the temporal change of the output value x 'is a signal which is suppressed (that is, the degree of suppression is larger) as the portion where the intensity X of the envelope Zc is larger in the detection signal Zb. In other words, of the detection signal Zb, a signal that is emphasized as the strength X of the envelope Zc decreases is the detection signal Ze. As understood from FIG. 7, the intensity of the portion I in the detection signal Ze is reduced as compared to the intensity of the portion I in the detection signal Zb of FIG. 4. Specifically, the intensity of the portion I in the detection signal Ze is suppressed more than the intensities of the other portions. That is, the detection signal Ze is reduced in the influence of the body movement as compared with the detection signal Zb.

  As understood from the above description, in the first embodiment, the smaller the strength of the envelope Zc of the detection signal Zb is emphasized in the detection signal Zb (the larger the strength X of the envelope Zc is, the more suppressed) ), It is possible to generate a detection signal Ze in which the influence of body movement is reduced. The signal processing unit 221 (specifically, the envelope generating unit 83, the arithmetic processing unit 85, and the dividing unit 87) is an envelope of the detection signal Zb among the detection signals Zb representing a temporal change in the intensity of light passing through the living body. The smaller the strength of the line Zc, the more it functions as an emphasizing element.

  The converter 223 in FIG. 2 converts the detection signal Ze generated by the signal processor 221 into a frequency spectrum F. FIG. 8 is a graph showing the frequency spectrum F generated by the converting unit 223. For generation of the frequency spectrum F, known frequency analysis such as fast Fourier transform (FFT) may be arbitrarily adopted. The pulse identification unit 225 identifies the pulse rate of the subject from the frequency spectrum F. Specifically, the pulse identification unit 225 identifies the pulse rate of the living body from the frequency of the peak at which the intensity is maximum in the frequency spectrum F. For example, in the example of FIG. 8, 60 bpm (beats per minute) is identified as the pulse rate.

  FIG. 9 is a flowchart of processing (hereinafter referred to as “pulse analysis processing”) executed by the control device 22. For example, the pulse analysis process of FIG. 9 is executed in response to an instruction from the user. When the pulse analysis process is executed, the preprocessing unit 81 generates a detection signal Zb from the detection signal Za (Sa1). The envelope generation unit 83 generates an envelope Zc of the detection signal Zb (Sa2). The arithmetic processing unit 85 calculates the correction value V from the intensity X of the envelope Zc (Sa3). The correction value V is calculated by the calculation of the above equation (1). The dividing unit 87 corrects the detection signal Zb generated by the preprocessing unit 81 with the correction value V (Sa4). Specifically, the detection signal Ze is generated by calculating the output value x 'from each intensity x of the detection signal Zb and the correction value V. The output value x 'is calculated by the operation of the above equation (2). The converter 223 converts the detection signal Ze into a frequency spectrum F (Sa5). The pulse identification unit 225 identifies a pulse rate from the frequency spectrum F (Sa6). The pulse analysis process is performed for each detection signal Za generated by the detection device 30. Steps Sa2 to Sa4 are processes (hereinafter referred to as "intensity correction process") of emphasizing a portion of the detection signal Zb where the intensity of the envelope Zc of the detection signal Zb is smaller. The portion of the pulse analysis device 100 that performs intensity correction processing functions as a signal processing device.

  The effects of the intensity correction process (signal processing method) will be described below. Here, for example, a configuration in which the intensity correction process is not performed (hereinafter, referred to as a “contrast example”) is assumed. In the comparison example, the pulse rate is identified from the frequency spectrum F of the detection signal Zb including the influence of body movement.

  FIG. 10 is a graph showing a detection signal Zb obtained by adding the influence of body movement to a portion I of a periodic waveform that fluctuates at 60 bpm, which corresponds to an appropriate pulse rate. The intensity of the portion I of the detection signal Zb is larger than the intensities of the other portions. FIG. 11 is a graph showing the frequency spectrum F generated by the comparative example. In the comparison example, the frequency spectrum F is generated by converting the detection signal Zb. As understood from FIG. 11, the intensity of the peak P1 representing body movement is larger than the intensity of the peak P2 representing the pulse rate. Thus, the frequency of peak P1 (30 bpm) may be identified as the pulse rate. That is, in the comparison example, the pulse rate can not be accurately identified.

  FIG. 12 is a graph showing a detection signal Ze generated from the detection signal Zb of FIG. 10 by the above-described intensity correction processing. As understood from FIG. 12, the intensity of the portion I in the detection signal Ze is suppressed as compared to the other portions (that is, the influence of the body movement is reduced). FIG. 13 is a graph showing a frequency spectrum F generated from the detection signal Ze. As understood from FIG. 13, the intensity of the peak P2 representing the pulse rate is larger than the peak P1 representing the body movement. Therefore, the frequency (60 bpm) of the peak P2 is identified with high accuracy as the pulse rate.

  As understood from the above description, in the first embodiment, the smaller the intensity X of the envelope Zc of the detection signal Zb in the detection signal Zb is emphasized, the detection signal in which the influence of body movement is reduced Ze can be generated. In the first embodiment, in particular, since the pulse rate is identified from the detection signal Ze, the pulse rate of the living body can be identified with high accuracy as compared with the comparative example (configuration for identifying the pulse rate from the detection signal Zb). it can. Also, as compared with a configuration in which the influence of body movement is reduced from the detection signal using a sensor (for example, an acceleration sensor) or the like for detecting body movement, a sensor for detecting body movement is not necessary. The device 100 can be miniaturized.

FIGS. 14 to 16 are graphs showing the detection signal Ze generated in the case where one or both of the coefficient γ and the suppression coefficient A of the equation (2) are set to 1. The detection signal Ze of FIGS. 14 to 16 is generated from the detection signal Zb of FIG. FIG. 14 exemplifies the case where both the coefficient γ and the suppression coefficient A are set to 1 (x ′ = x / X), and the coefficient γ is set to 1 and the suppression coefficient A is set to 10 in FIG. When set (x '= x / (A x X)) is illustrated, and when the coefficient γ is set to 1.3020 and the suppression coefficient A is set to 1 in Fig. 16 (x' = x / X ^γ ) It is illustrated. In FIG. 16, by setting only the coefficient γ to a value larger than 1, a clip occurs in the detection signal Ze in a range of 0 seconds to 4 seconds, and a part of the detection signal Ze (specifically, x Where 'is greater than 1 and less than -1) is missing. Further, in any case of FIGS. 14 to 16, the portion I in the detection signal Ze is not suppressed more than the other portions. That is, the influence of the body movement included in the detection signal Ze is not reduced. Therefore, as illustrated in FIG. 17, the frequency spectrum F generated from the detection signal Ze in FIGS. 14 to 16 has a larger intensity of the peak P1 representing body movement than the intensity of the peak P2 representing pulsation. That is, the frequency of the peak P1 representing body movement is identified as the pulse rate. As understood from the above description, by setting both the coefficient γ and the suppression coefficient A of the equation (2) to a value larger than 1, the influence of the body movement is reduced (that is, the part I is more than other parts The (suppressed) detection signal Ze can be generated.

  The determination as to whether or not the actual pulse analysis device (hereinafter referred to as “the actual product”) is performing the above-described intensity correction process is a cycle that fluctuates due to pulsation in the processing unit that calculates the pulse rate from the detection signal in the actual product. When a detection signal (for example, the detection signal Zb in FIG. 10) obtained by adding the influence of body movement to a waveform is input and the peak frequency representing the pulse rate is displayed as a pulse rate, the intensity correction process is adopted. Probability is high. On the other hand, when the frequency of the peak representing body movement is displayed as the pulse rate, it can be said that the intensity correction process is not employed.

Second Embodiment
A second embodiment of the present invention will be described. In addition, about the element which an operation | movement or a function is the same as 1st Embodiment in each form illustrated below, the code | symbol used by description of 1st Embodiment is diverted and detailed description of each is abbreviate | omitted suitably.

  In the first embodiment, the function of the signal processing unit 221 is realized by the control device 22, but a part of the function of the signal processing unit 221 may be realized by an electric circuit. In the second embodiment, the preprocessing unit 81 and the envelope generation unit 83 of the signal processing unit 221 are realized by an electric circuit, and the arithmetic processing unit 85 and the dividing unit 87 of the signal processing unit 221 are realized by the control device 22. Be done.

  FIG. 18 is a block diagram of the signal processing unit 221 according to the second embodiment. The signal processing unit 221 of the second embodiment includes a preprocessing unit 81, an A / D converter 82, an envelope generation unit 83, an A / D converter 84, an arithmetic processing unit 85, and a dividing unit 87. In the detection device 30 of the second embodiment, the A / D converter 34 of FIG. 2 is omitted.

  The preprocessing unit 81 in FIG. 18 generates a detection signal Zb ′ in a time domain including a component representing a beat from the analog detection signal Za ′ generated by the light receiving unit 32 of the detection device 30. The pre-processing unit 81 of the second embodiment extracts a component representing a beat in the detection signal Za ′, and normalizes the intensity of the extracted component so that it falls within a predetermined voltage range, thereby detecting the detection signal. Generate Zb '. The detection signal Zb 'is an analog voltage signal including a component representing a beat. The specific circuit configuration of the preprocessing unit 81 is arbitrary. The detection signal Zb ′ generated by the pre-processing unit 81 is supplied to the A / D converter 82 and the envelope generation unit 83. In the second embodiment, the intensity correction process is performed on the detection signal Zb '.

  The envelope generation unit 83 of the second embodiment generates an envelope Zc 'of the detection signal Zb' generated by the preprocessing unit 81. FIG. 19 is a circuit diagram of the envelope generation unit 83. As shown in FIG. The envelope generation unit 83 includes a full wave rectification circuit 91 and a smoothing circuit 93. The full wave rectification circuit 91 performs full wave rectification on the detection signal Zb '. Specifically, a voltage corresponding to the detection signal Zb 'is input between the first terminal T1 and the second terminal T2 of the full wave rectification circuit 91. The full-wave rectified detection signal Zb 'is smoothed by a smoothing circuit 93 implemented by a capacitive element. The voltage between the first terminal T3 and the second terminal T4 of the smoothing circuit 93 is output as an envelope Zc '. The envelope Zc ′ generated by the envelope generation unit 83 is supplied to the A / D converter 84.

  The A / D converter 82 of FIG. 18 generates a digital detection signal Zb from the analog detection signal Zb ′ generated by the preprocessing unit 81. The detection signal Zb is a digital signal corresponding to the intensity of the detection signal Zb '(that is, representing a temporal change in the intensity of light passing through the living body). The detection signal Zb generated by the A / D converter 82 is supplied to the divider 87. The A / D converter 84 generates a digital envelope Zc from the analog envelope Zc 'generated by the envelope generator 83. The envelope Zc generated by the A / D converter 84 is supplied to the arithmetic processing unit 85. The resolution of the A / D converter 82 and the A / D converter 84 is, for example, 12 bits (4096 steps).

  The arithmetic processing unit 85 of the second embodiment calculates the correction value V from the intensity of the envelope Zc generated by the A / D converter 84. Specifically, similarly to the first embodiment, the arithmetic processing unit 85 generates the correction envelope Zd by calculating the correction value V for each strength of the envelope Zc by the calculation of the equation (1) described above. Do.

  The dividing unit 87 of the second embodiment corrects the detection signal Zb generated by the A / D converter 82 with the correction value V calculated by the arithmetic processing unit 85. Specifically, as in the first embodiment, the dividing unit 87 calculates the output value x ′ from the intensity x of the detection signal Zb and the correction value V by the calculation of Equation (2). The detection signal Ze (time series of the output value x ') is generated by executing the calculation of the equation (2) for each of a plurality of different time points on the time axis. The coefficient γ and the suppression coefficient A of Equation (2) are defined by the aforementioned Equation (4). In the second embodiment, Dmax in equation (4) is the maximum value of the numerical values output by the A / D converter 82 and the A / D converter 84. As in the first embodiment, the detection signal Ze is converted into the frequency spectrum F, and the pulse rate is specified from the frequency spectrum F. Also in the second embodiment, the same effect as that of the first embodiment is realized.

Third Embodiment
FIG. 20 is a schematic view showing an example of use of the pulse analysis device 100 in the third embodiment. As illustrated in FIG. 20, the pulse analysis device 100 includes a detection unit 71 and a display unit 72 which are separately configured. The detection unit 71 includes the detection device 30 illustrated in the first embodiment. FIG. 21 illustrates a detection unit 71 mounted on the upper arm of a subject. As illustrated in FIG. 21, a detection unit 71 configured to be worn on the subject's wrist is also suitable.

  The display unit 72 includes the display device 23 exemplified in the first embodiment. For example, an information terminal such as a mobile phone or a smartphone is a preferred example of the display unit 72. However, the specific form of the display unit 72 is arbitrary. For example, a watch-type information terminal portable by a subject or a dedicated information terminal of the pulse analysis device 100 may be used as the display unit 72.

  An element for calculating the pulse rate from the detection signal Za (hereinafter referred to as “calculation unit”) is mounted on, for example, the display unit 72. The detection signal Za generated by the detection device 30 of the detection unit 71 is transmitted to the display unit 72 in a wired or wireless manner. The calculating unit (the signal processing unit 221, the converting unit 223, the pulse specifying unit 225) of the display unit 72 calculates the pulse rate from the detection signal Za and displays it on the display device 23.

  The calculating unit may be mounted on the detection unit 71. The calculating unit calculates the pulse rate from the detection signal Za generated by the detecting device 30, and transmits data for displaying the pulse rate to the display unit 72 by wire or wirelessly. The display device 23 of the display unit 72 displays the pulse rate indicated by the data received from the detection unit 71.

  In the pulse analysis device 100 according to the second embodiment, the display processing unit shown in FIGS. 20 and 21 includes the arithmetic processing unit 85, the division unit 87, the conversion unit 223, and the pulse identification unit 225 in the signal processing unit 221 as calculation units. It is possible to mount it on 72.

<Modification>
Each form illustrated above can be variously deformed. The aspect of a specific deformation | transformation is illustrated below. It is also possible to appropriately merge two or more aspects arbitrarily selected from the following exemplifications.

(1) In the first embodiment, the time series of the movement maximum value of the detection signal Zb is generated as the envelope Zc, but the method of generating the envelope Zc is not limited to the above example. The control device 22 may realize the function of the envelope generation unit 83 (the full wave rectification circuit 91 and the smoothing circuit 93) exemplified in the second embodiment. Specifically, the control device 22 inverts the negative number part of the detection signal Zb to an integer, and smoothes the inverted signal. Alternatively, the envelope Zc may be generated by Hilbert transform of the detection signal Zb. However, the configuration of the first embodiment in which the time series of the movement maximum value of the detection signal Zb is generated as the envelope Zc, or the second embodiment in which the envelope Zc is generated by full-wave rectification and smoothing on the detection signal Zb ′ According to the configurations of the two embodiments, there is an advantage that the processing load of the pulse analysis device 100 is reduced as compared with the configuration in which the envelope Zc is generated by Hilbert transform.

(2) In the first embodiment, the intensity correction process is performed on the detection signal Zb, and in the second embodiment, the intensity correction process is performed on the detection signal Zb ′. The signal which performs a correction process is not limited to the above illustration. In the first embodiment, for example, the intensity correction process may be performed on the detection signal Za. In the second embodiment, for example, the intensity correction process may be performed on the detection signal Za '. That is, in the signal processing unit 221, the preprocessing unit 81 is not essential. As understood from the above description, the signal to be subjected to the intensity correction process is arbitrary as long as it is a detection signal representing a temporal change in the intensity of light passing through the living body. The signal processing unit 221 is a factor that emphasizes a portion of the detection signal (for example, the detection signal Zb or the detection signal Zb ′) representing a temporal change in the intensity of light having passed through the living body as the portion having a smaller envelope of the detection signal Expressed comprehensively.

(3) In each of the above-described embodiments, the calculations of Equation (1) and Equation (2) are exemplified as the intensity correction process, but among the detection signals representing the temporal change of the intensity of light passing through the living body, The specific content of the intensity correction process is arbitrary, as long as it is possible to emphasize the smaller the envelope intensity.

(4) In the first embodiment, after the process of generating the envelope Zc from the detection signal Zb (step Sa2 of FIG. 9), the process of calculating the correction value V from the intensity X of the envelope Zc (step Sa3 of FIG. 9) Although the correction value is calculated from the intensity x of the detection signal Zb, a time-series envelope of the correction value may be generated. Specifically, the arithmetic processing unit 85 calculates the correction value by multiplying the strength x of the detection signal Zb by the power of γ and multiplying by the suppression coefficient A. The envelope generation unit 83 generates a time-series envelope (that is, a correction envelope) of the correction value calculated by the arithmetic processing unit 85. The division unit 87 generates the detection signal Ze by correcting the detection signal Zb with the intensity of the correction envelope (dividing the intensity x of the detection signal Zb by the intensity of the correction envelope).

(5) In the above-described embodiments, the coefficient γ and the suppression coefficient A of the equation (1) are defined by the equation (4), but the coefficient γ and the suppression coefficient A are arbitrary as long as they have values larger than one. However, according to the structure which defines coefficient (gamma) and the suppression coefficient A by Numerical formula (4), output value x 'can be carried out within the predetermined range (-1 to +1).

(6) In each of the above-described embodiments, the pulse rate is specified, but an index other than the pulse rate may be calculated from the detection signal Ze generated by the signal processing unit 221. For example, oxygen saturation in blood (SPO2) may be calculated. Moreover, it is also possible to specify the condition of the subject's pulse rate from a plurality of stages (for example, abnormal / high / normal, etc.) from the calculated pulse rate and notify the subject of the condition.

(7) In each of the above-described embodiments, the pulse analysis device 100 configured as a single device is illustrated, but as illustrated below, a plurality of elements of the pulse analysis device 100 can be realized as separate devices from each other . In the following description, an element for specifying the pulse rate from the detection signal Za ′ is referred to as “calculation unit 29”. The calculating unit 29 includes the elements illustrated in FIG. 2 (the signal processing unit 221, the converting unit 223, and the pulse specifying unit 225).

  Although the pulse analysis device 100 including the detection device 30 is illustrated in the above-described embodiments, a configuration in which the detection device 30 is separated from the pulse analysis device 100 is also assumed as illustrated in FIG. The detection device 30 is, for example, a portable optical sensor module mounted on a measurement site H such as the subject's wrist or upper arm. The pulse analysis device 100 is realized by an information terminal such as a mobile phone or a smartphone. The pulse analyzer 100 may be realized by a watch-type information terminal. The detection signal Za ′ generated by the detection device 30 is transmitted to the pulse analysis device 100 in a wired or wireless manner. The calculating unit 29 of the pulse analysis device 100 specifies the pulse rate from the detection signal Za ′ and displays it on the display unit 23. As understood from the above description, the detection device 30 can be omitted from the pulse analysis device 100.

  In each of the above-described embodiments, the pulse analysis device 100 including the display device 23 is illustrated. However, as illustrated in FIG. 23, a configuration in which the display device 23 is separated from the pulse analysis device 100 is also assumed. The calculating unit 29 of the pulse analysis device 100 calculates the pulse rate from the detection signal Za ′, and transmits data for displaying the pulse rate to the display unit 23. The display device 23 may be a dedicated display device, but may be mounted on, for example, an information terminal such as a mobile phone or a smartphone, or a wristwatch-type information terminal portable by a subject. The pulse rate calculated by the calculating unit 29 of the pulse analysis device 100 is transmitted to the display device 23 by wire or wirelessly. The display device 23 displays the pulse rate received from the pulse analysis device 100. As understood from the above description, the display device 23 can be omitted from the pulse analysis device 100.

  As exemplified in FIG. 24, a configuration in which the detection device 30 and the display device 23 are separated from the pulse analysis device 100 (calculation unit 29) is also assumed. For example, the pulse analysis device 100 (calculation unit 29) is mounted on an information terminal such as a mobile phone or a smartphone.

  Note that the signal processing unit 221 can be mounted on the detection device 30 in a configuration in which the detection device 30 and the pulse analysis device 100 are separated. The detection signal Ze generated by the signal processing unit 221 is transmitted from the detection device 30 to the pulse analysis device 100 by wire or wirelessly. As understood from the above description, the signal processing unit 221 may be omitted from the pulse analysis device 100.

  In the pulse analysis device 100 of the second embodiment, the calculation processing unit 85 and the division unit 87 of the signal processing unit 221, the conversion unit 223, and the pulse identification unit 225 are illustrated in FIGS. 22 to 24 as the calculation unit 29. The form can be adopted. Of the signal processing unit 221, the functions (preprocessing unit 81, A / D converter 82, envelope generation unit 83, and A / D converter 84) realized by an electric circuit are mounted on the detection device 30. .

(8) In each of the above-described embodiments, the wristwatch-type pulse analyzer 100 including the housing 12 and the belt 14 is illustrated. However, the specific embodiment of the pulse analyzer 100 is arbitrary. For example, a patch type that can be applied to the subject's body, an ear worn type that can be worn on the subject's ear, a finger worn type that can be worn on the subject's fingertip (for example, nailed), or can be worn on the subject's head Any form of pulse analysis apparatus 100 such as a head-mounted type can be employed.

(9) In the above-described embodiments, the pulse rate of the subject is displayed on the display device 23. However, the configuration for notifying the subject of the pulse rate is not limited to the above examples. For example, it is also possible to notify the subject of the pulse rate by voice. In the ear worn pulse analysis apparatus 100 that can be attached to the subject's ear, a configuration in which the pulse rate is notified by voice is particularly preferable. In addition, it is not essential to inform the subject of the pulse rate. For example, the pulse rate calculated by the pulse analysis device 100 may be transmitted from the communication network to another communication device. In addition, the pulse rate may be stored in a storage device (not shown) of the pulse analysis device 100 or a portable recording medium that is removable from the pulse analysis device 100.

(10) The pulse analysis device 100 according to each of the above-described embodiments is realized by the cooperation of an arithmetic processing unit such as a CPU and a program, as described above. The program according to the preferred embodiment of the present invention may be provided in the form of being stored in a computer readable recording medium and installed on the computer. Moreover, it is also possible to provide a computer stored in a recording medium of the distribution server in the form of distribution via a communication network. The recording medium is, for example, a non-transitory recording medium, and is preferably an optical recording medium (optical disc) such as a CD-ROM, but any known medium such as a semiconductor recording medium or a magnetic recording medium may be used. Recording media of the form Note that non-transitory recording media include any recording media except transient propagation signals, and do not exclude volatile recording media.

DESCRIPTION OF SYMBOLS 100 ... Pulse analyzer, 12 ... Housing | casing part, 14 ... Belt, 22 ... Control apparatus, 23 ... Display apparatus, 30 ... Detection apparatus, 31 ... Light emission part, 32 ... Light reception part, 33 ... Drive circuit, 34 ... A / D converter, 221: signal processing unit, 223: conversion unit, 225: pulse identification unit, 81: pre-processing unit, 82: A / D converter, 83: envelope generation unit, 84: A / D converter, 85 ... arithmetic processing unit, 87 ... division unit, 91 ... full wave rectification circuit, 93 ... smoothing circuit, 71 ... detection unit, 72 ... display unit.

Claims (7)

A signal processing apparatus comprising: a signal processing unit that emphasizes a portion of a detection signal representing a temporal change in intensity of light passing through a living body, the smaller the intensity of the envelope of the detection signal. The signal processing unit
An envelope generation unit that generates the envelope of the detection signal;
An arithmetic processing unit that calculates a correction value by multiplying the strength of the envelope by γ (γ> 1) and multiplying by the suppression coefficient A (A>1);
The signal processing apparatus according to claim 1, further comprising: a division unit that divides the intensity of the detection signal by the correction value. The signal processing device according to claim 2, wherein the envelope generation unit generates a time series of movement maximum values of the detection signal as the envelope. The envelope generation unit
A full wave rectification circuit for full wave rectification of the detection signal;
The signal processing device according to claim 2, further comprising: a smoothing circuit that smoothes the full wave rectified signal. A signal processing unit that emphasizes a portion of a detection signal representing a temporal change in the intensity of light passing through a living body, in which the intensity of the envelope of the detection signal is smaller;
A converter that converts the signal processed by the signal processor into a frequency spectrum;
And a pulse identification unit that identifies the pulse rate of the living body from the frequency of the peak at which the intensity is maximum among the frequency spectrum. A signal processing method of emphasizing a portion where the intensity of the envelope of the detection signal is smaller in the detection signal representing the temporal change of the intensity of the light passing through the living body. A program that causes a computer to function as a signal processing unit that emphasizes a portion of a detection signal representing a temporal change in the intensity of light passing through a living body, where the intensity of the envelope of the detection signal is smaller.

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