JP2012183139A - Measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the accuracy in setting of the sensitivity of a sensor part in a measuring device.SOLUTION: The measuring device includes: the sensor part 10 having a photoelectric conversion part 2 for outputting a signal including information about a measuring object and an amplifier 3 for amplifying the signal including the information about the measuring object; and a sensitivity adjusting part 6 for detecting a difference between the maximum value and minimum value in a predetermined period of a sensor signal dx output from the sensor part 10 as an amplitude value to adjust the sensitivity of the sensor part 10 based on the ratio of an amplitude value occupying a predetermined allowable amplitude value.

Description

  The present invention relates to a measuring device and the like.

  A measurement device that detects the displacement of a measurement target is described in Patent Document 1, for example. The measurement apparatus described in Patent Literature 1 includes a gain setting unit that resets the gain of an amplifier that amplifies a detected signal in accordance with the magnitude of the amplified signal.

  The pulsation detection device is a device for detecting a pulsation derived from a heartbeat of a human body. For example, a signal (pulse wave signal) from a pulse wave sensor unit attached to an arm, a palm, a finger, or the like. Thus, a signal component (body motion influence signal) generated due to the influence of body motion of a human body is removed as noise, and a signal derived from a heartbeat (beat signal) is detected. For example, Patent Literature 2 to Patent Literature 4 describe a pulsometer of the type worn on a person's finger or wrist.

Japanese Patent Laid-Open No. 10-234684 JP 2005-198829 A JP 2007-54471 A JP 2005-131426 A

  When the measurement apparatus starts operation, it is necessary to set the gain of the amplifier to an appropriate gain corresponding to the state of the measurement target. The gain setting is preferably performed accurately, and is preferably performed quickly.

  According to at least one aspect of the present invention, for example, the gain setting accuracy of the amplifier can be increased. Also, for example, the gain setting of the amplifier can be performed quickly.

  (1) One aspect of the measurement apparatus according to the present invention is a sensor unit including a sensor element that outputs a signal including information on a measurement target, an amplifier that amplifies the signal including information on the measurement target, and the sensor unit. The difference between the maximum value and the minimum value of the sensor signal output from the predetermined period is detected as an amplitude value, and the sensitivity of the sensor unit is determined based on the degree of the ratio of the amplitude value to the predetermined allowable amplitude value. A sensitivity adjustment unit for adjustment.

  In this aspect, the sensitivity of the sensor unit is adjusted (controlled) based on “the degree of the ratio of the amplitude value of the sensor signal to the predetermined allowable amplitude value”. The amplitude value of the sensor signal in the predetermined period is determined by the difference between the maximum value and the minimum value in the predetermined period.

  In this aspect, the ratio of the amplitude of the sensor signal to the allowable amplitude value (dynamic range) is detected. Therefore, for example, the sensitivity of the sensor unit can be set so that the amplitude of the sensor signal is as large as possible (for example, maximized) within the allowable amplitude value (dynamic range). Therefore, the sensitivity of the sensor unit can be set to an appropriate sensitivity (for example, as large as possible) corresponding to the state of the measurement target.

  (2) In another aspect of the measuring device of the present invention, the first time is the time when the first time has elapsed from the measurement start time when the measuring device started the measurement, and the second time has elapsed from the first time. When the time point is the second time point and the measurement start time point to the second time point is the first period, the sensitivity adjustment unit sets the sensitivity of the sensor unit to a predetermined setting sensitivity in the first period, The predetermined period is a period from the first time point to the second time point, and at the second time point, based on the degree of the ratio of the detected amplitude value to the predetermined allowable amplitude value, Adjust the sensitivity of the sensor section.

  In this aspect, the time point at which the first time has elapsed from the measurement start time point is defined as the first time point, the time point at which the second time has elapsed from the first time point is defined as the second time point, and the time from the measurement start time point to the second time point is defined as the first time point. Period. Here, the first time is T1, the second time is T2, and the first period is TX.

  In this aspect, measurement is started in a state where the gain of the amplifier is set to a predetermined initial sensitivity. Detected in a period from the first time point to the second time point (corresponding to the predetermined period in the above aspect (1)) at the second time point when the first period (TX) has elapsed after the measurement was started. Based on “the degree of the ratio of the amplitude value of the sensor signal to the predetermined allowable amplitude value”, the setting of the gain of the amplifier (review of the gain) is executed. That is, when the first period (TX) has elapsed after the start of measurement, the gain of the amplifier becomes an appropriate value according to the state of the measurement target. If the length of the first period (TX) is set appropriately, the gain of the amplifier can be optimized early after the start of measurement. That is, the initial gain setting of the amplifier can be performed accurately and quickly.

  In the initial period of measurement, for example, noise accompanying the start of circuit operation is likely to occur. In this aspect, by setting the first time from the measurement start time to the first time to an appropriate length, that is, by causing the period when noise is likely to occur within the first time to end, the “sensor The accuracy of detection of “the degree of the ratio of the amplitude value of the signal to the predetermined allowable amplitude value” can be increased.

  (3) In another aspect of the measuring apparatus of the present invention, the sensitivity adjustment unit detects whether the amplitude value of the sensor signal exceeds the predetermined allowable amplitude value during the predetermined period, and The sensitivity of the sensor unit is adjusted based on the detection result of whether or not the allowable amplitude value is exceeded.

  In this aspect, the sensitivity adjustment unit detects whether the amplitude value of the sensor signal exceeds a predetermined allowable amplitude value (dynamic range), and performs sensitivity adjustment of the sensor unit based on the detection result. A phenomenon in which the amplitude value of the sensor signal exceeds a predetermined allowable amplitude value (dynamic range) may be referred to as “shake-out”. When the shakeout occurs, the value of the sensor signal output from the amplifier is saturated.

  The occurrence of shaking out means that an excessive signal exceeding a predetermined amplitude allowable value (dynamic range) is input to the amplifier. In this case, the sensitivity adjustment unit can reduce the sensitivity of the sensor unit, thereby preventing the shakeout from occurring.

  (4) In another aspect of the measuring apparatus of the present invention, the sensor unit includes a sampling unit that samples a signal output from the amplifier at a predetermined time interval, and extracts a sample. When the amplitude value of the sensor signal exceeds the predetermined allowable amplitude value for a plurality of adjacent samples in the series, the sensitivity adjustment unit determines that the amplitude value of the sensor signal for the plurality of adjacent samples is the predetermined value. The number of times that the allowable amplitude value is exceeded is detected, and the sensitivity of the sensor unit is adjusted based on the number of times.

  In this aspect, the sensitivity adjustment unit detects the number of times that the amplitude value of the sensor signal has exceeded a predetermined allowable amplitude value (the number of shakeouts) for a plurality of samples adjacent in time series, and based on the number of times, Adjust the sensitivity of the part. It is considered that the greater the degree of disturbance of the signal input to the amplifier, the higher the possibility of increasing the number of shakes.

  Therefore, the sensitivity adjustment unit can perform the sensitivity adjustment of the sensor unit based on the number of shakes (in this case, the process of appropriately reducing the sensitivity), thereby preventing the shakes from occurring.

  (5) In another aspect of the measuring apparatus of the present invention, the sensor unit includes a sampling unit that samples a signal output from the amplifier at a predetermined time interval to extract a sample, and in the predetermined period, When the amplitude value of the sensor signal exceeds the predetermined allowable amplitude value for a plurality of samples adjacent to each other in the series, the sensitivity adjustment unit determines that the amplitude value of the sensor signal exceeds the predetermined allowable amplitude value. The sensitivity of the sensor unit is adjusted based on the maximum number of samples with the maximum number of adjacent samples in the series.

  In this aspect, the sensitivity adjustment unit adjusts the sensitivity of the sensor unit based on the maximum number of samples in which the number of adjacent samples in the time series becomes maximum when the amplitude value of the sensor signal exceeds a predetermined allowable amplitude value.

  It is considered that the maximum number of samples is likely to increase as the degree of excessiveness of the signal input to the amplifier increases. Therefore, the sensitivity adjustment unit can perform the gain adjustment of the amplifier based on the maximum number of samples (in this case, the process of appropriately reducing the gain), thereby preventing the shakeout from occurring.

  (6) In another aspect of the measuring apparatus of the present invention, the amplitude value of the sensor signal exceeds an upper limit value of the predetermined allowable amplitude value in the predetermined period, or the amplitude value of the sensor signal is the predetermined value. The sensitivity of the sensor unit is adjusted based on whether the lower limit value of the allowable amplitude value is exceeded.

  In this aspect, the sensitivity adjustment unit adjusts the sensitivity of the sensor unit based on whether the amplitude value of the sensor signal exceeds the upper limit value of the predetermined allowable amplitude value or exceeds the lower limit value of the predetermined allowable amplitude value. adjust.

  Here, the phenomenon in which the amplitude value of the sensor signal exceeds the upper limit value of the predetermined allowable amplitude value may be referred to as “forward swing out”, and the amplitude value of the sensor signal is the lower limit value of the predetermined allowable amplitude value. A phenomenon that exceeds this may be referred to as “negative swing out”.

  By detecting the information including the information on the direction when the shake occurs, the information that is the basis for adjusting the sensitivity of the sensor unit is increased. Therefore, the sensitivity of the amplifier can be accurately adjusted.

  (7) In another aspect of the measurement apparatus of the present invention, the sensor unit includes a sampling unit that samples a signal output from the amplifier at a predetermined time interval to extract a sample, and in the predetermined period, When the amplitude value of the sensor signal exceeds the predetermined allowable amplitude value, the sensitivity adjustment unit is adjacent to the sample amplitude value exceeding the predetermined allowable amplitude value and the sample exceeding the predetermined allowable amplitude value. A difference with the amplitude value of the matching sample is detected, and the sensitivity of the sensor unit is adjusted based on the difference.

  In this aspect, the sensitivity adjustment unit detects a difference between the amplitude value of the sample exceeding the predetermined allowable amplitude value and the amplitude value of the sample adjacent to the sample exceeding the predetermined allowable amplitude value. The sensitivity of the sensor unit is adjusted based on the difference.

  For example, the sharper the waveform of the signal (input signal to the amplifier) that causes the shake-off, the greater the difference. Here, it is assumed that the sharpness of the waveform of the signal is high and low. In this case, in order to keep the amplitude value of the sensor signal output from the amplifier within a predetermined allowable amplitude value (dynamic range), the gain of the amplifier must be smaller when the sharpness is high. Conceivable. The sensitivity adjustment unit adjusts the gain of the amplifier by paying attention to the difference, thereby preventing the shakeout from occurring.

  (8) In another aspect of the measuring apparatus of the present invention, the sensitivity adjustment unit determines the gain of the amplifier based on the degree of the ratio of the amplitude value of the sensor signal to the allowable amplitude value of the sensor signal. A gain setting value determining unit that determines a gain setting value, and a gain adjusting unit that adjusts the gain of the amplifier based on the gain setting value determined by the gain setting value determining unit.

  In this aspect, the sensitivity adjustment unit includes a gain setting value determination unit and a gain adjustment unit. When the gain setting value is determined by the gain setting value determination unit, the gain adjustment unit adjusts the gain of the amplifier based on the gain setting value. In this aspect, the gain of the amplifier can be controlled by a parameter called a gain setting value.

  (9) In another aspect of the measurement apparatus of the present invention, the measurement apparatus is a pulsation detection apparatus that detects a pulsation signal derived from the pulsation of the subject as the measurement target.

  In this aspect, for example, the accuracy and speed of the initial gain setting of the amplifier can be increased, so that the pulsation detection device corresponds to a useful pulse wave signal (a sensor signal) that can be used to detect the pulsation signal. ) Can be obtained. Therefore, the accuracy of beat detection of the beat detection device is increased.

  As described above, according to at least one aspect of the present invention, for example, the accuracy of gain setting of an amplifier can be increased. Also, for example, the gain setting of the amplifier can be performed quickly.

The figure which shows the structure of an example of a measuring device Diagram showing an example of a specific configuration of an amplifier FIGS. 3A and 3B are diagrams schematically illustrating an example of gain adjustment (an example of increasing gain). 4 (A), 4 (B), and 4 (C) schematically show examples of gain adjustment (examples of decreasing gain). The figure which shows an example of the timing of gain adjustment 6A and 6B are diagrams showing specific examples of gain adjustment. The figure which shows the structure of an example of a pulsation detection apparatus. Flow chart showing an example of operation of the pulsation detection device FIGS. 9A and 9B are diagrams showing examples of gain adjustment in the case where the pulse wave signal d is not completely broken out in the period from 3 seconds to 4 seconds after the measurement is started. FIG. 10A and FIG. 10B are diagrams showing examples of gain adjustment in the case where the pulse wave signal d is lost in the period from 3 seconds to 4 seconds after the start of measurement. FIG. 11A and FIG. 11B are diagrams showing an example of mounting the pulsation detecting device to a subject.

  Hereinafter, specific description will be given with reference to the drawings. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

(First embodiment)
(Configuration of measuring device)
FIG. 1 is a diagram illustrating a configuration of an example of a measurement apparatus. The measurement apparatus 102 shown in FIG. 1 outputs a signal including information on a measurement target (for example, a person as a subject: not shown), a photoelectric conversion unit 2 as a sensor element, and a signal including information on the measurement target. The amplitude of the difference between the maximum value and the minimum value in a predetermined period of the sensor unit 10 including the amplifier 3 to be amplified and the A / D converter 4 as the sampling unit, and the sensor signal dx output from the sensor unit 10 A sensitivity adjustment unit 6 that adjusts the sensitivity of the sensor unit 10 based on the degree of the ratio of the amplitude value to a predetermined allowable amplitude value (dynamic range), and a timing unit (timer) that outputs timing control information Etc.) 9, a threshold storage unit 11 storing amplitude thresholds, and a frequency analysis unit 50. The A / D converter 4 as a sampling unit samples the signal output from the amplifier 3 at predetermined time intervals and extracts samples.

  The amplifier 3 is a variable gain amplifier. The gain GN of the amplifier 3 is adjusted (controlled) by the sensitivity adjustment unit 6.

  The sensitivity adjustment unit 6 determines a gain setting value that is information for determining the gain of the amplifier 3 based on the degree of the ratio of the amplitude value of the sensor signal dx to the allowable amplitude value (dynamic range) of the sensor signal dx. It is preferable to include a value determining unit 7 and a gain adjusting unit 8 that adjusts the gain GN of the amplifier 3 based on the gain setting value determined by the gain setting value determining unit 7. The sensitivity adjustment unit 6 may refer to a signal gx indicating the frequency analysis result of the sensor signal dx output from the frequency analysis unit 50, for example, when adjusting the sensitivity of the sensor unit 10.

  The gain setting value determination unit 7 includes a first determination unit 7a that determines a gain setting value when the gain GN is increased, and a second determination unit 7b that determines a gain setting value when the gain GN is decreased. . That is, the gain setting value determination unit 7 can determine an appropriate gain setting value both when the gain GN is increased and when the gain GN is decreased. When the gain setting value is determined by the gain setting value determination unit 7, the gain adjustment unit 8 adjusts the gain GN of the amplifier 3 based on the gain setting value. Thus, the gain GN of the amplifier 3 can be controlled by a parameter called a gain setting value.

  Next, a specific configuration example of the amplifier (variable gain amplifier) 3 will be described. FIG. 2 is a diagram illustrating an example of a specific configuration of the amplifier. The amplifier 3 includes a first-stage amplification unit 410 that amplifies the signal output from the photoelectric conversion unit 2 that is a sensor element with a constant gain, a low-pass filter 420 that removes frequency components below a predetermined frequency, and a variable gain amplification unit 430. And cascade connection.

  The variable gain amplifying unit 430 includes analog switches 431 to 434 whose on / off is controlled by the signal levels of the gain adjustment signals d1 to d4. Here, the analog switches 431 to 434 are turned on when the level of the corresponding gain adjustment signal (any one of d1 to d4) becomes the H level.

  When the signal level of one of the gain adjustment signals d1 to d4 is H level, the signal level of the other gain adjustment signal is L level. Accordingly, only one of the analog switches 431 to 434 is turned on.

  Here, assuming that the resistance values of the feedback resistors R1 to R5 are, for example, R1 = 20 kΩ, R2 = 40 kΩ, R3 = 80 kΩ, R4 = 160 kΩ, and R5 = 320 kΩ, the gain in the variable gain amplifying unit 430 is the gain adjustment signal d1 When the analog switch 431 is turned on, the signal is doubled. When the gain adjustment signal d2 is at the H level and the analog switch 432 is turned on, the signal is quadrupled. Further, when the gain adjustment signal d3 becomes H level and the analog switch 433 is turned on, the gain adjustment signal d3 becomes 8 times, and when the gain adjustment signal d4 becomes H level and the analog switch 434 turns on, it becomes 16 times. Become. Since each operational amplifier operates with a single power supply, the input signal is pulled up to a voltage VDD / 2 that is half the power supply voltage VDD. The above configuration is an example, and modifications and applications can be made as appropriate.

(First gain adjustment operation)
Next, the case where the gain GN of the amplifier 3 is adjusted for the first time after the measurement is started (that is, the first gain adjustment operation) will be described. This will be described with reference to FIGS.

  As described above, the sensitivity adjustment unit 6 adjusts (controls) the sensitivity of the sensor unit 10 based on the degree of the ratio of the amplitude value of the sensor signal dx to the predetermined allowable amplitude value (dynamic range). The amplitude value of the sensor signal dx in a predetermined period (for example, a period of 0 to 4 seconds after the start of measurement) is determined by a difference value between the maximum value and the minimum value in the predetermined period.

  Further, as described above, the predetermined allowable amplitude value corresponds to, for example, a dynamic range that defines a range that the value of the sensor signal dx can take. The sensitivity of the sensor unit 10 is determined according to the gain of the amplifier 3. That is, the sensitivity of the sensor unit 10 can be adjusted by adjusting the gain of the amplifier 3.

  The sensitivity adjustment unit 6 detects the ratio of the amplitude of the sensor signal dx to the allowable amplitude value (dynamic range). Therefore, for example, the gain of the amplifier 3 can be set so that the amplitude of the sensor signal dx is as large as possible (for example, maximum) within the allowable amplitude value (dynamic range). Therefore, the gain of the amplifier 3 can be set to an appropriate gain (for example, as large as possible) corresponding to the initial state of the measurement target.

FIG. 3A and FIG. 3B are diagrams schematically illustrating an example of gain adjustment (an example in which gain is increased). In the example of FIGS. 3A and 3B, the measurement is started with the gain setting value set to 4 (initial value). In this case, the gain GN of the amplifier 3 is 16 (= 2 ⁴ ). In addition, the amplitude value of the sensor signal dx in a predetermined period (for example, a period of 0 second to 4 seconds after the start of measurement) is Q1a. The amplitude value Q1a of the sensor signal dx is determined by the difference between the maximum value M2 and the minimum value M1. The allowable amplitude value (dynamic range) that can be taken by the sensor signal dx is DL. The lower limit value of the allowable amplitude value DL is LL, and the upper limit value is LU (specifically, 512).

  Here, the sensitivity adjustment unit 6 (specifically, the first determination unit 7a of the gain setting value determination unit 7) sets the amplitude value Q1a of the sensor signal dx to, for example, five amplitude threshold values (16, 32, 64, The first amplitude threshold value to the fifth amplitude threshold value having respective values of 128 and 256, and thereby the degree of the ratio of the amplitude value Q1a of the sensor signal dx to the allowable amplitude value DL is determined.

Here, the midpoint value of the allowable amplitude value of the sensor signal dx is set to 0, and the upper limit value is set to 512 (= 2 ⁹ ). Further, when the amplitude value (Q1a) of the sensor signal dx in the predetermined period is x and the amplitude threshold value is y, the first determination unit 7a of the gain setting value determination unit 7 included in the sensitivity adjustment unit. Specifies an amplitude threshold value corresponding to the minimum y satisfying x <y from the first amplitude value to the fifth amplitude value.

  As a result, in the example of FIG. 3A, the first amplitude threshold value (value 16) is specified. The first determination unit 7a of the gain setting value determination unit 7 determines the value of the gain setting value (here, m) according to the identified amplitude threshold. In the example of FIG. 3A, the gain setting value m = 9 is determined.

Further, the gain adjusting unit 8 adjusts the gain GN of the amplifier 3 so as to be a value determined based on the calculation formula GN = 2 ^m , where GN is the gain of the amplifier 3. The timing of this adjustment is, for example, a point in time when the above-described predetermined period (a period of 0 second to 4 seconds after the start of measurement) ends. In the example of FIG. 3A, the gain GN is adjusted to 512 (= 2 ⁹ ). This corresponds to 32 times the gain GN when the gain setting value m = 4.

In the example of FIG. 3B, the amplitude value of the sensor signal dx is Q1b. In this case, the fifth amplitude threshold (value 256) is selected as the amplitude threshold. In this case, the gain setting value m is determined to be 5. As a result, the gain GN of the amplifier 3 is adjusted to 32 (= 2 ⁵ ). This corresponds to twice the gain GN when the gain setting value m = 4.

  In this way, when a predetermined period elapses after the start of measurement, the first gain adjustment is executed, and the gain GN of the amplifier 3 is adjusted to an appropriate value. That is, early and appropriate initial gain adjustment is realized.

4A and 4B are diagrams schematically illustrating an example of gain adjustment (an example in which gain is decreased). In the example of FIGS. 4A and 4B, the measurement is started with the gain setting value set to 4 (initial value). In this case, the gain GN of the amplifier 3 is 16 (= 2 ⁴ ). In addition, the amplitude value of the sensor signal dx in a predetermined period (for example, a period of 0 second to 4 seconds after the start of measurement) is Q1a. The amplitude value Q1a of the sensor signal dx is determined by the difference between the maximum value M2 and the minimum value M1. The allowable amplitude value (dynamic range) that can be taken by the sensor signal dx is DL. The lower limit value of the allowable amplitude value DL is LL, and the upper limit value is LU (specifically, 512).

  When reducing the gain GN of the amplifier 3, the second determination unit 7b of the gain setting value determination unit 7 specifies the value of the gain setting value m. The sensitivity adjustment unit 6 detects, for example, whether the amplitude value of the sensor signal dx exceeds a predetermined allowable amplitude value DL (LL, LU) in order to determine how much to decrease the gain GN. Then, the sensitivity adjustment of the sensor unit 10 is executed based on the detection result. Note that a phenomenon in which the amplitude value of the sensor signal dx exceeds a predetermined allowable amplitude value (dynamic range) may be referred to as “shaking out”.

  For example, the sensitivity adjustment unit 6 detects whether or not the amplitude value of the sensor signal dx has exceeded a predetermined allowable amplitude value DL in a predetermined period (for example, a period of 0 to 4 seconds after the start of measurement). Then, the sensitivity of the sensor unit 10 may be adjusted based on the presence or absence of shaking. A specific example of sensitivity adjustment will be described later with reference to FIG.

  When the shakeout occurs, the value of the sensor signal dx output from the amplifier 3 is saturated. The occurrence of shaking out means that an excessive signal exceeding a predetermined amplitude allowable value (dynamic range) is input to the amplifier. In the example of FIG. 4 (A), the shakeout has occurred.

  In this case, the sensitivity adjustment unit 6 can reduce the gain GN of the amplifier 3 to prevent the shakeout from occurring.

  In addition, in the predetermined period, the fluctuation of the amplitude of the sensor signal dx exceeding the predetermined allowable amplitude value DL occurred for a plurality of samples adjacent in the time series (may be referred to as a plurality of samples consecutive in the time series). In this case, the sensitivity adjustment unit 6 may detect the number of occurrences of shaking of a plurality of adjacent samples in a predetermined period, and adjust the sensitivity of the sensor unit 10 based on the number of times.

  It is considered that the greater the degree of disturbance of the signal input to the amplifier 3, the higher the possibility that the number of shakeouts will increase. Therefore, the sensitivity adjusting unit 6 can adjust the gain GN of the amplifier 3 based on the number of shakes (a process for appropriately reducing the gain), thereby preventing the shakes from being lost.

  In the example of FIG. 4A, the swing-out on the upper limit LU side is continued three times (time t10 to t11, time t12 to t13, time t14 to t15), and the swing-off on the lower limit value LL side is continued three times. (Time t11 to t12, time t13 to t14, time t15 to t16). In this case, the number of shakeouts is 3.

  In addition, in the predetermined period, when the fluctuation of the amplitude of the sensor signal dx exceeding the predetermined allowable amplitude value occurs in a plurality of adjacent samples, the sensitivity adjustment unit 6 has the maximum number of adjacent samples in time series. The number of samples at the time of shaking may be detected as the maximum number of samples, and the sensitivity of the sensor unit 10 may be adjusted based on the maximum number of samples.

  It is considered that the maximum number of samples is likely to increase as the degree of excessiveness of the signal input to the amplifier 3 increases. Therefore, the sensitivity adjustment unit 6 can adjust the gain GN of the amplifier 3 based on the maximum number of samples (in this case, a process of appropriately reducing the gain) to prevent the shakeout from occurring.

  For example, it is assumed that the shakeout with the maximum number of adjacent samples in the time series is a shakeout as shown in FIG. In this case, since the samples SP1 to SP3 are continuous, the maximum number of adjacent samples in the time series is 3.

  In addition, when the amplitude of the sensor signal dx exceeds the predetermined allowable amplitude value during the predetermined period, the sensitivity adjustment unit 6 causes the amplitude value of the sensor signal dx to exceed the upper limit LU of the predetermined allowable amplitude value. Alternatively, the sensitivity of the sensor unit 10 may be adjusted based on whether the lower limit LL of the predetermined allowable amplitude value is exceeded.

  Here, the phenomenon in which the amplitude value of the sensor signal dx exceeds the upper limit LU of the predetermined allowable amplitude value may be referred to as “positive swing out”, and the amplitude value of the sensor signal dx is the predetermined allowable amplitude value. A phenomenon that exceeds the lower limit LL of “N” may be referred to as “negative swing out”.

  By detecting the direction including the information of the direction when the shake is lost, the information that is the basis for adjusting the sensitivity GN of the sensor unit 10 increases. Therefore, the sensitivity GN of the amplifier 3 can be accurately adjusted.

  In the example of FIG. 4A, the forward swing is generated at time t10 to t11, time t12 to t13, and time t14 to t15. In addition, the negative swing occurs at times t11 to t12, times t13 to t14, and times t15 to t16.

  In addition, when the amplitude value of the sensor signal dx exceeds the allowable amplitude value DL in a predetermined period, the amplitude value of the sample exceeding the predetermined allowable amplitude value and the sample exceeding the predetermined allowable amplitude value are adjacent to each other. A difference from the amplitude value of a sample that does not exceed the permissible amplitude value (a sample that has not been shaken out) may be detected, and the sensitivity of the sensor unit 10 may be adjusted based on the difference.

  For example, it is considered that the difference becomes larger as the waveform of the signal (input signal to the amplifier 3) causing the shake-out is sharper. Here, it is assumed that the sharpness of the waveform of the signal is high and low. In this case, in order to keep the amplitude value of the sensor signal dx output from the amplifier 3 within the allowable amplitude value DL, it is considered that the gain GN of the amplifier 3 must be smaller when the sharpness is high. It is done. The sensitivity adjustment unit 6 pays attention to the difference and adjusts the gain GN of the amplifier 3 to prevent the shakeout from occurring.

  In the example of FIG. 4C, the difference between the sample SP3 that has been shaken off and the sample SP4 that is adjacent to the sample SP3 and has not been shaken off is dm. The sensitivity adjustment unit 6 can determine the magnitude of the difference dm by comparing the difference dm with, for example, a predetermined threshold value.

  Next, an example of the timing of the first gain adjustment will be described. FIG. 5 is a diagram illustrating an example of gain adjustment timing. FIG. 5 shows a signal waveform of the sensor signal dx. In FIG. 5, the horizontal axis indicates the elapsed time (seconds) from the measurement start time, and the vertical axis indicates the amplitude value of the sensor signal dx.

  In FIG. 5, the measurement start time when the measurement apparatus 102 starts measurement is set as time t0. A time point at which the first time T1 has elapsed from the time t0 is defined as a first time point (time t1), and a time point at which the second time T2 has elapsed from the first time point (time t1) is defined as a second time point (time t2). Also, the first period TX is from the measurement start time (time t0) to the second time (time t2).

  A relationship of 0 ≦ T1 <TX and 0 <T2 ≦ TX is established between the first time T1, the second time T2, and the first period TX.

  In the first period TX, the sensitivity adjustment unit 6 sets the sensitivity of the sensor unit 10 to a predetermined initial setting sensitivity (for example, the gain GN of the amplifier 3 is set to 16). In the period (second time T2) from the first time point (time t1) to the second time point (time t2) as the predetermined period, the amplitude value of the sensor signal dx is an allowable amplitude value DL (−512 to 512). Detects the ratio of the percentage. Then, the sensitivity adjustment unit 6 adjusts the sensitivity GN of the sensor unit 10 to the sensitivity determined based on the degree of the ratio of the detected amplitude value to the predetermined allowable amplitude value at the second time point (time t2). To do.

  That is, in the above example, the gain GN of the amplifier 3 is adjusted to an appropriate value according to the state of the measurement target when the first period (TX) has elapsed from the measurement start time (time t0). If the length of the first period (TX) is set appropriately, the gain of the amplifier 3 can be optimized early after the start of measurement. In the above example, the first time TX is set to 4 seconds. Therefore, the initial gain setting of the amplifier 3 can be performed accurately and quickly.

  In the initial period of measurement, for example, noise accompanying the start of circuit operation is likely to occur. In the example of FIG. 5, the first time T1 from the measurement start time to the first time (time t1) is set to an appropriate length, that is, there is a time when excessive noise is likely to occur within the first time T1. By terminating the processing, it is possible to improve the detection accuracy to the extent that the amplitude value of the sensor signal dx occupies the predetermined allowable amplitude value DL.

  In the example of FIG. 5, excessive noise (transient response noise or the like) of the sensor signal dx has converged within the first time T1, and therefore, an adverse effect on the initial gain setting due to excessive noise is avoided.

(Specific example of gain adjustment)
Next, a specific example of gain adjustment will be described with reference to FIG. 6A and 6B are diagrams illustrating specific examples of gain adjustment.

  FIG. 6A shows a specific example when the gain is increased. In this example, the allowable amplitude value (dynamic range) of the sensor signal dx is set to 0 to 1023 (for 10 bits). In the example of FIG. 6A, the amplitude threshold value, gain setting, required sensitivity (GN), and upper limit value of the amplitude value are shown for each of cases 1 to 5.

  In the example of FIG. 6A, the midpoint value of the allowable amplitude value of the sensor signal dx is set to 0, a maximum range of 512 is set in the positive direction, and a range of −512 is set in the negative direction.

The gain setting value of the amplifier 3 is m (m is a natural number satisfying 4 ≦ m ≦ 9), and the value of the gain setting value m of the amplifier 3 at the measurement start time of the measuring apparatus 102 (that is, the initial setting value). 4 and the gain of the amplifier 3 (that is, the initial setting gain) at this time is 16 (= 2 ⁴ ).

  In addition, as an amplitude threshold value serving as a reference for determining the degree of the ratio of the amplitude value of the sensor signal dx in the predetermined period to the allowable amplitude value, a first amplitude threshold value of 16, a second amplitude threshold value of 32, and a value of A third amplitude threshold value of 64, a fourth amplitude threshold value of 128, and a fifth amplitude threshold value of 256 are used.

  Here, when the amplitude value of the sensor signal dx in the predetermined period is x and the amplitude threshold value is y, the first determination unit 7a of the gain setting value determination unit 7 sets the minimum y satisfying x <y. A corresponding amplitude threshold is specified from the first amplitude value to the fifth amplitude value.

(Case 1)
The first determination unit 7a sets the gain setting value m of the amplifier 3 to 9 when the specified amplitude threshold is the first amplitude threshold (value 16). The gain adjustment unit 8 sets the gain GN of the amplifier to 512 (= 2 ⁹ ) when the value of the gain setting value m of the amplifier 3 is 9.

(Case 2)
The first determination unit 7a sets the gain setting value m of the amplifier 3 to 8 when the specified amplitude threshold is the second amplitude threshold (value 32). The gain adjusting unit 8 sets the gain GN of the amplifier 3 to 256 (= 2 ⁸ ) when the gain setting value m of the amplifier 3 is 8.

(Case 3)
The first determination unit 7a sets the gain setting value m of the amplifier 3 to 7 when the specified amplitude threshold is the third amplitude threshold (value 64). The gain adjusting unit 8 sets the gain of the amplifier 3 to 128 (= 2 ⁷ ) when the value of the gain setting value m of the amplifier 3 is 7.

(Case 4)
The first determination unit 7a sets the value of the gain setting value m of the amplifier 3 to 6 when the specified amplitude threshold is the fourth amplitude threshold (value 128). The gain adjusting unit 8 sets the gain of the amplifier to 64 (= 2 ⁶ ) when the value of the gain setting value m of the amplifier 3 is 6.

(Case 5)
The first determination unit 7a sets the gain setting value m of the amplifier 3 to 5 when the specified amplitude threshold is the fifth amplitude threshold (value 256). The gain adjustment unit 8 sets the gain of the amplifier to 32 (= 2 ⁵ ) when the value of the gain setting value m of the amplifier 3 is 5.

(Case 6)
Case 6 is when the amplitude value of the sensor signal dx is larger than the fifth amplitude threshold value (value 256). In this case, according to FIG. 6B, gain adjustment (adjustment for decreasing the gain) is performed in consideration of the number of shakes and the like.

  As described above, in the example of FIG. 6A, the sensitivity adjustment unit 6 converts the sensor signal dx from the first amplitude threshold value to the fifth amplitude value having five amplitude threshold values (16, 32, 64, 128, and 256). (Amplitude threshold value) is determined to determine “the degree of the ratio of the amplitude value of the sensor signal dx to the predetermined allowable amplitude value”.

Here, the midpoint value of the allowable amplitude value of the sensor signal dx is set to 0, and the upper limit value is set to 512 (= 2 ⁹ ). Further, when the amplitude value of the sensor signal dx in the predetermined period is x and the amplitude threshold value is y, the gain setting value determination unit included in the sensitivity adjustment unit corresponds to the minimum y satisfying x <y. An amplitude threshold value is specified from the first amplitude value to the fifth amplitude value.

Then, the gain setting value determination unit 7 (first determination unit 7a) determines the gain setting value of the amplifier 3 according to which of the first amplitude threshold value to the fifth amplitude value is the specified amplitude threshold value. Determine the value of m. Further, when the gain of the amplifier 3 is GN, the gain adjusting unit 8 adjusts the gain GN of the amplifier 3 so as to be a value determined based on a calculation formula of GN = 2 ^m . According to the example of FIG. 6A, the sensor signal dx is compared with a plurality of amplitude thresholds, and the gain setting value m of the amplifier 3 and the gain GN of the amplifier 3 are calculated according to the comparison result. be able to.

  In the example of FIG. 6B, a specific example in the case of decreasing the gain is shown. In the example of FIG. 6B, the midpoint value of the allowable amplitude value of the sensor signal dx is set to 0, a maximum range of 512 is set in the positive direction, and a range of −512 is set in the negative direction. A case that does not fall within this range is called a shakeout. Here, the shake in the positive direction is a case where the amplitude value of the sensor signal dx exceeds the upper limit value (512) of the dynamic range, and the shake in the negative direction exceeds the lower limit value (−512) of the dynamic range. Is less than In the example of FIG. 6B, the gain setting value m is not set to 0 in the first gain setting value review process after the start of measurement.

  When it is determined as case 6 by the determination according to FIG. 6 (A), the second determination unit 7b of the gain setting value determination unit 7 executes the determination according to FIG. 6 (B) to obtain the value of the gain setting value m. decide.

(Case 7)
The gain setting value m is set to 1 when the value obtained by adding the number of swings in the positive direction and the number of swings in the negative direction is 10 or more.

(Case 8)
The gain setting value m is set to 1 when the number of consecutive shakeouts is 4 or more.

(Case 9)
The gain setting value m is set to 1 when the amplitude value of the sensor signal dx exceeds a predetermined allowable amplitude value and the maximum number of samples adjacent to each other in the time series is the maximum.

(Case 10)
The gain setting value m is set to 1 when the difference between the sample that caused the shakeout and the sample adjacent to this sample (the shakeout sample difference) is 128 or more.

(Case 11)
The gain setting value m is set to 3 when the number of swing-outs in the positive direction is 2 or more, or when the number of swing-outs in the negative direction is 2 or more. However, this is only an example and can be modified. For example, a difference may be provided in the adjusted sensitivity between the case where the swing is positive and the case where the swing is negative.

(Case 12)
The gain setting value m is set to 2 when the difference between the sample that has shaken off and the sample adjacent to this sample (the shaken sample difference) is 64 or more.

(Case 13)
The gain setting value m is set to 3 when the number of shakes in the positive direction is 1 or more or the number of shakes in the negative direction is 1 or more.

(Case 14)
Although there is no shaking, the gain setting value m is set to 3 if the peak value of the sensor signal dx is 388 or more of the dynamic range (−512 to 512).

(Case 15)
Although there is no shaking, the gain setting value m is set to 4 if the peak value of the sensor signal dx is less than 388 in the dynamic range (−512 to 512).

  Each judgment condition shown in FIG. 6B is an example, and only one of the judgment conditions can be used, or a plurality of judgment conditions can be used in any combination. is there.

(Second Embodiment)
In the present embodiment, the configuration and operation of a pulsation detection device as an example of a measurement device will be described. In the present embodiment, for example, high accuracy and quickness of the initial gain setting of the amplifier are realized. Therefore, the pulsation detection device of the present embodiment can obtain a useful pulse wave signal (corresponding to a sensor signal) that can be used for detecting a pulsation signal. Therefore, the accuracy of beat detection of the beat detection device is increased.

  FIG. 7 is a diagram illustrating a configuration of an example of a pulsation detection device. In FIG. 7, the same reference numerals are given to portions common to FIG. 1, and description thereof is omitted. A pulsation detection device 100 shown in FIG. 7 is a kind of sensor device that detects pulsation signals derived from the pulsation of a subject (including humans and animals), biological information such as heartbeats corresponding to the pulsation signals, and the like. It is.

  Here, the pulsation means a movement that occurs when the periodical contraction and relaxation of not only the heart but also the internal organs are repeated medically. Here, the movement as a pump in which the heart periodically sends blood is called pulsation. The heart rate refers to the number of heart beats per minute. The pulse rate refers to the number of pulsations in the peripheral blood vessels. When the heart pumps out blood, pulsation occurs in the artery, and this number is called the pulse rate or simply the pulse. As long as the pulse is measured with an arm, it is usually referred to as a pulse rate instead of a heart rate in medical terms. Moreover, in the following description, the term body movement is used. Body movement means, in a broad sense, all movement of the body (broad movement in a broad sense). The subject's steady and periodic body movements (for example, the movement of the arm (for example, the vicinity of the body of the pulsation detecting device) that is periodic, such as walking or jogging) is defined as a narrowly defined body movement. May be.

(overall structure)
A pulsation detection device 100 shown in FIG. 7 includes a pulse wave sensor unit 10 that outputs a pulse wave signal d that may include a pulsation signal, a sensitivity adjustment unit 6, a timing unit (timer) 9, and a threshold value. Storage unit (memory) 11, pulse wave signal storage unit (first buffer memory 13 for storing pulse wave signal d data for 4 seconds, and second buffer memory for storing pulse wave signal d data for 16 seconds 15), a filter unit 30 including an adaptive filter 32 and a body motion component removal filter 34, a body motion sensor unit (acceleration sensor, gyro sensor, etc.) 20, a body motion signal storage unit 22, and a frequency analysis unit 50, a history storage unit 70, a subject information acquisition unit (pulse rate / calorie consumption calculation unit) 90, a display processing unit 92, and a display unit 94.

  The frequency analyzing unit 50 includes a signal distributing unit 39, a frequency resolving unit 40 (first frequency resolving unit 40a, second frequency resolving unit 40b, third frequency resolving unit 40c) and a pulse wave in which frequency trend information 44 is accumulated. Signal analysis unit 42, post-processing unit 60 (including a peak order sorting unit 62, a correlation determination unit 64, a pulsation / body motion separation unit 66, and a pulsation presentation spectrum specifying unit 68), and a pulsation presentation spectrum capturing process Part 80.

  The pulse wave sensor unit 10 is, for example, a photoelectric pulse wave sensor unit and a pulse wave sensor unit based on the principle thereof. The pulse wave sensor unit 10 outputs a pulse wave signal d (corresponding to the sensor signal dx in the first embodiment) that may include a pulsation signal.

  The pulse wave sensor unit 10 receives reflected light generated by a light source (not shown) such as an LED and the output light of the light source reflected by a blood vessel (not shown in FIG. 1) as a biological information source, and converts it into an electrical signal. A photoelectric conversion unit 2 as a sensor element to be converted, an amplifier (variable gain amplifier) 3 for amplifying the output signal of the photoelectric conversion unit 2, and an A / D converter 4 as a sampling unit are included.

  The sensitivity of the pulse wave sensor unit 10 is determined by the gain (amplification factor) of the amplifier 3. The gain of the amplifier 3, that is, the sensitivity of the pulse wave sensor unit 10 is adjusted by the sensitivity adjustment unit 6. The sensitivity adjustment unit 6 is configured by, for example, an AGC circuit (automatic gain control circuit) that automatically adjusts the gain of the amplifier 3.

  The sensitivity adjustment unit 6 performs an initial gain adjustment of the amplifier 3 based on the data of the pulse wave signal d for 4 seconds accumulated in the first buffer memory 13. The sensitivity adjustment unit 6 performs the sensitivity adjustment operation of the amplifier 3 described in the first embodiment. For example, the sensitivity adjuster 6 adjusts the amplifier 3 so that the amplitude value of the pulse wave signal d becomes a predetermined value (predetermined level), for example, the maximum within a predetermined allowable amplitude value (dynamic range). Adjust (control) the gain. The sensitivity adjustment unit 6 may refer to a signal gx indicating the frequency analysis result of the sensor signal dx output from the frequency analysis unit 50, for example, when adjusting the sensitivity of the sensor unit 10.

  The body motion sensor unit 20 detects the body motion of the subject and outputs a body motion signal f derived from the body motion. Similarly to the pulse wave sensor unit 10, the body motion sensor unit 20 also includes an amplifier (not shown). The gain of the amplifier may be feedback controlled by an AGC circuit having the same configuration as that of the sensitivity adjustment unit 6.

  A signal for 4 seconds of the pulse wave signal d output from the pulse wave sensor unit 10 is accumulated in the first buffer memory 13. The pulse wave signal d for 4 seconds is transferred to the second buffer memory 15 at a cycle of 4 seconds. The second buffer memory 15 is a FIFO (first-in first-out) memory, and the pulse wave signal for 16 seconds is updated every 4 seconds. The pulse wave signal for 16 seconds is accumulated because it is necessary to observe the transition of the signal in a certain time width and carefully examine the presence or absence of correlation when identifying the pulsation component by frequency analysis. is there.

  The filter unit 30 minimizes noise included in the input signal. Further, the body motion component removal filter 34 minimizes, for example, the body motion signal component included in the pulse wave signal d.

  The frequency analysis unit 50 performs predetermined filtering based on the pulse wave signal d or the filtered signal e obtained by performing filtering (by the filter unit 30) for suppressing noise included in the pulse wave signal d on the pulse wave signal d. Frequency analysis is performed every time (for example, every 4 seconds), and a pulsation presentation spectrum indicating a pulsation signal is specified.

  The signal distribution unit 39 supplies the post-filter signal e to the first frequency decomposition unit (Fast Fourier Transform unit: FFT) 40a, and supplies the pulse wave signal d before the filter to the third frequency decomposition unit 40c. The body motion signal f is supplied to the second frequency decomposition unit 40b.

  The post-processing unit 60 includes a peak order sorting unit 62 that sorts the frequency spectrum in descending order of the spectrum value, and the main spectrum having the highest peak order is the spectrum of the pulsation signal of the latest past (for example, 4 seconds before). A correlation determination unit 64 that performs correlation determination, a pulsation / noise separation unit 66 that separates a pulsation signal and a noise component using a result of the correlation determination, and 66 is separated from noise by pulsation / noise separation processing. And a pulsation presentation spectrum specifying unit 68 that specifies the spectrum of the pulsation component as a pulsation presentation spectrum.

  If the identification of the pulsation presentation spectrum is successful, the subject information acquisition unit (pulse rate / calorie consumption calculation unit) 90 consumes the pulse rate, which is the biological information of the subject, and consumption information, which is incidental information about the subject's motion. Calculate at least one of the calories. The pulse rate is calculated based on, for example, the frequency of the pulsation presentation spectrum. The calorie consumption is calculated based on the pulse rate.

  The calculated subject information (at least one of the pulse rate and calorie consumption) is supplied from the subject information acquisition unit (pulse rate / calorie consumption calculation unit) 90 to the display unit 94 via the display processing unit 92. As a result, for example, a numerical value indicating the pulse wave number or the calorie consumption is displayed on the display unit 94. In addition, you may display the change on the time axis of the detected pulse instead of the pulse rate in the form of a signal waveform or a graph (notice in a broad sense).

  Further, the pulsation presentation spectrum acquisition processing unit 80 included in the frequency analysis unit 50 starts an operation when, for example, the pulsation presentation spectrum specifying unit 68 fails to specify the pulsation presentation spectrum based on the filtered signal e. To do. The pulsation presentation spectrum acquisition processing unit 80, for example, based on the pulse wave signal d before filtering (having a signal value larger than the signal after filtering because the signal does not attenuate by filtering), for example, past pulsation signals Attempts to capture the pulsation presentation spectrum by determining the correlation based on the frequency trend.

  The pulse wave signal analysis unit 42 analyzes the frequency spectrum of the pulse wave signal d, evaluates the signal state of the pulse wave signal d, and also shows frequency trend information 44 of the pulsation presentation spectrum indicating the pulsation signal, and frequency analysis. Result information 45 is acquired. The signal state of the pulse wave signal d is evaluated based on, for example, the degree of cleanness of the pulse wave signal d (degree of noise amount of the pulse wave signal d). The degree of cleanliness of the pulse wave signal d may be evaluated using an evaluation index. As an evaluation index, a ratio of spectral values of main frequency spectra, or statistical information (statistical index) such as standard deviation and deviation value may be used.

  The history storage unit 70 stores frequency information of the specified or captured pulsation presentation spectrum and calculated subject information (pulse rate and calorie consumption) in time series. Each unit can refer to the stored information as necessary.

(Operation example of pulsation detection device)
FIG. 8 is a flowchart showing an example of the operation of the pulsation detection device. The pulsation detection device 100 starts detection (measurement) of the pulsation signal with the gain setting value m = 4 of the amplifier 3 (gain GN = 16 of the amplifier 3) (step ST1). The pulse wave signal d for 4 seconds is accumulated in the pulse wave signal accumulation unit 12 (step ST2).

  Next, it is determined whether it is the first gain adjustment timing (step ST3). Here, a second time point when 4 seconds have elapsed from the start time of detection (measurement) is set as the first gain adjustment timing.

  When Y in step ST3, the gain adjustment of the amplifier 3 is executed by the sensitivity adjustment unit 6. The sensitivity adjustment unit 6 is obtained as a preliminary process from the detection (measurement) start time (time when the elapsed time is 0 seconds) to the first time when 3 seconds have passed. Then, the sampling value of the pulse wave signal d is replaced with the median value (that is, the amplitude intermediate value) of the allowable amplitude value (dynamic range) (step ST4). That is, in the period from the start of detection (measurement) to the first point where 3 seconds elapse, there is a possibility that a lot of noise due to a transient response or the like is included. The amplitude value of the pulse wave signal d obtained in the (period) is ignored, and a safe amplitude value (amplitude median value) is substituted to facilitate subsequent processing.

  Next, the sensitivity adjustment unit 6 sets the sampling value of the pulse wave signal d obtained during a period from the first time point when 3 seconds have elapsed from the start point of detection (measurement) to the second time point when 4 seconds have elapsed. Based on this, the degree of the ratio of the amplitude value of the pulse wave signal d to the allowable amplitude value (dynamic range) is detected (step ST5). Based on the detection result, the sensitivity adjustment unit 6 determines the gain setting value m (step ST6). As a result, the gain of the amplifier 3 is uniquely determined.

  Next, the sensitivity adjustment unit 6 confirms whether or not a shake-out has been detected in the detection process of step ST5 (step ST7). If Y in step ST7, the process proceeds to step ST8, and if N, the process proceeds to step ST12. In step ST8, the sensitivity adjustment unit 6 obtains from the first time point 3 seconds after the detection (measurement) start time stored in the first buffer memory 13 to the second time point 4 seconds have passed. The sampling value of the pulse wave signal d thus obtained is replaced with the median value (that is, the amplitude intermediate value) of the allowable amplitude value (dynamic range) (step ST8). In the case of the occurrence of shaking out in this period (3 to 4 seconds after the start of measurement), the reliability of the pulse wave signal d is low, so the amplitude value of the pulse wave signal d is ignored and a safe amplitude value ( (Median amplitude) is substituted to facilitate subsequent processing.

  Further, when the answer is N in step ST3, the sensitivity adjustment unit 6 confirms whether or not the period is within 20 seconds from the detection start (measurement start) of the pulsation signal (step ST9). When Y is determined in step ST9, a gain adjustment process (gain adjustment process during normal operation) of the amplifier 3 is executed (step ST11). For example, the sensitivity adjustment unit 6 performs a gain adjustment process based on a comparison between the peak value of the pulse wave signal d and a threshold value.

  If NO in step ST9, the sensitivity adjustment unit 6 determines whether 20 seconds have elapsed since the previous gain adjustment (step ST10). In step ST10, when Y, the process proceeds to step ST11. When N, the process proceeds to step ST12.

  In step ST12, a pulse rate calculation process or the like is executed. In step ST13, the pulsation detection device 100 confirms whether or not a measurement end instruction is input. In step ST13, when the result is Y, the processing of the pulsation signal is terminated, and when it is N, the process returns to step ST2.

(Example of actual gain adjustment)
(Gain adjustment example 1)
FIG. 9A and FIG. 9B are diagrams showing examples of gain adjustment in the case where the pulse wave signal d is not completely broken out during the period from 3 seconds to 4 seconds after the start of measurement. FIG. 9 (A) shows the waveform of the pulse wave signal d in the period from 0 second to 4 seconds after the start of measurement. The horizontal axis indicates the elapsed time (seconds) after the start of measurement, and the vertical axis indicates the signal value (−512 to 512) of the pulse wave signal d.

  FIG. 9B shows the transition of the waveform of the pulse wave signal d and the gain setting value of the amplifier 3 during the period from 0 to 16 seconds after the start of measurement. In FIG. 9B, the horizontal axis indicates the elapsed time (seconds) after the start of measurement, the left vertical axis indicates the signal value (−512 to 512) of the pulse wave signal d, and the right vertical axis indicates The gain setting value m is shown. In FIG. 9B, the gain setting value of the amplifier 3 is indicated by a thick broken line.

  In the example of FIG. 9A, the maximum value of the sampling value of the pulse wave signal d is 503 and the minimum value is 478 in the period of 3 seconds to 4 seconds after the start of measurement. The amplitude value (= maximum value−minimum value) is 25. This case corresponds to Case 2 shown in FIG. Therefore, 8 is selected as the gain setting value m.

  As a result, as shown in FIG. 9B, after 4 seconds from the start of measurement, the waveform of the pulse wave signal d having an amplitude about half of the dynamic range (−512 to 512) can be obtained. did it. That is, it was possible to adjust the gain of the amplifier 3 (that is, the sensitivity of the sensor unit 6) to an appropriate value very early after the start of measurement.

(Gain adjustment example 2)
FIG. 10A and FIG. 10B are diagrams illustrating examples of gain adjustment in the case where the pulse wave signal d is lost in the period from 3 seconds to 4 seconds after the start of measurement. FIG. 10A shows the waveform of the pulse wave signal d in the period from 0 second to 4 seconds after the start of measurement. The horizontal axis indicates the elapsed time (seconds) after the start of measurement, and the vertical axis indicates the signal value (−512 to 512) of the pulse wave signal d.

  FIG. 10B shows the transition of the waveform of the pulse wave signal d and the gain setting value of the amplifier 3 in the period from 0 second to 16 seconds after the start of measurement. In FIG. 10B, the horizontal axis represents the elapsed time (seconds) after the start of measurement, the left vertical axis represents the signal value (−512 to 512) of the pulse wave signal d, and the right vertical axis represents The gain setting value m is shown. In FIG. 10B, the gain setting value of the amplifier 3 is indicated by a thick broken line.

  In the example of FIG. 10 (A), in the period of 3 to 4 seconds elapsed from the start of measurement, the number of positive swings is one, the number of negative swings is zero, and the peak value of the pulse wave signal d Is 1023. This case corresponds to case 13 shown in FIG. Therefore, 3 is selected as the gain setting value m.

  As a result, as shown in FIG. 10B, after 4 seconds from the start of measurement, the waveform of the pulse wave signal d having an amplitude about half the dynamic range (−512 to 512) can be obtained. did it. That is, it was possible to adjust the gain of the amplifier 3 (that is, the sensitivity of the sensor unit 6) to an appropriate value very early after the start of measurement.

  FIG. 11A and FIG. 11B are diagrams showing an example of mounting the pulsation detection device to a subject.

  The example of FIG. 11A is an example of a wristwatch type pulsation detecting device. A base unit 400 including the pulse wave sensor unit 10 and the display unit 94 is attached to the left wrist 200 of a subject (user) by a wristband 300.

  The example of FIG. 11B is an example of a finger-mounted pulsation detecting device. The pulse wave sensor unit 10 is provided at the bottom of a ring-shaped guide 302 for insertion into the fingertip of the subject.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. In addition, a term described together with a different term having a broader meaning or the same meaning at least once in the specification or the drawings can be replaced with the different term anywhere in the specification or the drawings.

2 photoelectric conversion part as sensor element, 3 amplifier,
4 A / D converter as sampling unit, 6 Sensitivity adjustment unit,
7 Gain setting value determination unit (including the first determination unit 7a and the second determination unit 7b),
8 gain adjustment unit, 9 timing unit (timer), 11 threshold storage unit (memory),
10 pulse wave sensor unit (sensor unit), 12 pulse wave signal storage unit,
20 Body motion sensor (acceleration sensor, gyro sensor, etc.)
30 filter section, 34 body motion component removal filter,
40 (40a to 40c) Frequency resolving unit, 42 Pulse wave signal analyzing unit,
44 frequency trend information, 45 frequency analysis result information, 50 frequency analysis section,
60 post-processing unit, 62 peak order sorting unit, 64 correlation determination unit,
66 pulsation / body motion separation unit (beat / noise separation unit), 68 pulsation presentation spectrum specifying unit,
70 history storage,
80 pulsation presentation spectrum capture processing unit,
90 Subject information acquisition unit (pulse rate / calorie consumption calculation unit),
92 display processing unit, 94 display unit, 100 pulsation detecting device as measuring device

Claims (9)

A sensor unit that outputs a signal including information on the measurement target; and an amplifier that amplifies the signal including information on the measurement target; and
A difference between a maximum value and a minimum value in a predetermined period of a sensor signal output from the sensor unit is detected as an amplitude value, and the sensor unit is based on a degree of a ratio of the amplitude value to a predetermined allowable amplitude value. And a sensitivity adjusting unit that adjusts the sensitivity of the measuring device. The measuring device according to claim 1,
The time when the first time has elapsed from the measurement start time when the measurement device started measurement is defined as the first time point, the time when the second time has elapsed from the first time point is defined as the second time point, and the time from the measurement start time to the first time When the first period is up to 2 time points,
The sensitivity adjuster is
In the first period, the sensitivity of the sensor unit is set to a predetermined setting sensitivity,
The predetermined period is a period from the first time point to the second time point,
And the sensitivity of the said sensor part is adjusted based on the grade of the ratio for which the said detected amplitude value occupies for the said predetermined | prescribed permissible amplitude value in the said 2nd time. The measuring device according to claim 1 or 2,
The sensitivity adjustment unit detects whether or not the amplitude value of the sensor signal exceeds the predetermined allowable amplitude value in the predetermined period, and based on a detection result whether or not the predetermined value exceeds the predetermined allowable amplitude value. A measuring apparatus for adjusting the sensitivity of the sensor unit. The measuring device according to claim 1 or 2,
The sensor unit has a sampling unit that samples a signal output from the amplifier at a predetermined time interval to extract a sample,
When the amplitude value of the sensor signal exceeds the predetermined allowable amplitude value for a plurality of samples that are adjacent in time series in the predetermined period, the sensitivity adjustment unit is configured to output the sensor signal for the plurality of adjacent samples. A measuring device that detects the number of times an amplitude value exceeds the predetermined allowable amplitude value and adjusts the sensitivity of the sensor unit based on the number of times. The measuring device according to claim 1 or 2,
The sensor unit has a sampling unit that samples a signal output from the amplifier at a predetermined time interval to extract a sample,
When the amplitude value of the sensor signal exceeds the predetermined allowable amplitude value for a plurality of samples that are adjacent in time series in the predetermined period, the sensitivity adjustment unit determines that the amplitude value of the sensor signal is the predetermined allowable amplitude. A measuring apparatus, wherein the sensitivity of the sensor unit is adjusted based on a maximum number of samples that exceed the maximum number of adjacent samples in time series. The measuring device according to claim 1 or 2,
Based on whether the amplitude value of the sensor signal exceeds the upper limit value of the predetermined allowable amplitude value or the amplitude value of the sensor signal exceeds the lower limit value of the predetermined allowable amplitude value in the predetermined period A measuring apparatus for adjusting the sensitivity of the sensor unit. The measuring device according to claim 1 or 2,
The sensor unit has a sampling unit that samples a signal output from the amplifier at a predetermined time interval to extract a sample,
In the predetermined period, when the amplitude value of the sensor signal exceeds the predetermined allowable amplitude value, the sensitivity adjustment unit determines the amplitude value of the sample that exceeds the predetermined allowable amplitude value and the predetermined allowable amplitude value. A measurement device that detects a difference from an amplitude value of a sample adjacent to a sample that exceeds the threshold value and adjusts the sensitivity of the sensor unit based on the difference. The measuring device according to claim 1,
The sensitivity adjustment unit includes a gain setting value determination unit that determines a gain setting value that is information for determining a gain of the amplifier based on a degree of a ratio of an amplitude value of the sensor signal to an allowable amplitude value of the sensor signal. ,
A gain adjusting unit that adjusts the gain of the amplifier based on the gain setting value determined by the gain setting value determining unit;
A measuring apparatus comprising: It is a measuring device in any one of Claims 1-8,
The measurement apparatus is a pulsation detection apparatus that detects a pulsation signal derived from the pulsation of a subject as the measurement target.

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