JPS6234534A - Wave form processor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application This invention relates to a waveform processing device used in a waveform processing device that detects the absolute value and relative value of a waveform whose level changes over time, such as a waveform processing device used in an electronic blood pressure monitor. Regarding equipment.

(B) Conventional technology Conventional electronic blood pressure monitors have a pressure sensor that converts the pressure of a cuff wrapped around the upper arm into a pulse signal with a frequency corresponding to the pressure, and a counter that counts this pulse signal. Some devices detect cuff pressure by reading out a corresponding cuff pressure from data stored in a cuff pressure conversion data storage section based on a count value.

In this type of electronic blood pressure monitor, a sensor whose resistance value or capacitance value changes in proportion to pressure, that is, converts pressure into a resistance value or capacitor capacitance value, is used as the pressure sensor section.

If there is a proportional relationship between pressure and resistance value R or capacitance value C, then for Pm, ・C・・・・・・(1) For Pm, ”・R・・・・・・(2) However, K +, K+': Expressed as a constant.

Furthermore, if the pulse signal generating section is a voltage-side oscillator that includes a resistor and a capacitor, and a capacitor or resistor whose capacitance value and resistance value change depending on the above-mentioned pressure is used, the pulse oscillation frequency f is r = Kz/ (To C:
l) --(2)r = K2'/(R''Kx')
-...(21'However, K z, K 2',
It can be expressed as K: l, K 3'' constant.

Above (11(21) or (21(21'), the relationship between pulse signal frequency f and pressure is f = 4/ (P 10Ks) --f3) However,
Ka, ni-,: Can be expressed as a constant.

Now, by converting cuff pressure into frequency and sampling, CP
[To import into J, Qmmllg is 1000 K fiz300 mm1
700 KI [y.

, the above equation (3) becomes F (Hz) −700,000,000/ (Pmm
l1g+700)...(4).

In this case, a sampling time of approximately 2 mm5ec is required to obtain an accuracy of 1 mmHg for cuff pressure detection,
1 between O and 300mm11g between mn+5ecO,
400 to 2000 pulses will be input to the counter.

(c) Problems to be Solved by the Invention In electronic blood pressure monitors, in order to measure blood pressure, in addition to direct current changes in cuff pressure, that is, absolute values, pulse wave components (relative values) superimposed on this direct current component are measured. There are cases where you want to detect. Detecting this pulse wave component requires higher accuracy than absolute value detection, and if the absolute value has an accuracy of 1 mm 11 g, for example, an accuracy of Q, 1 mm 11 g is required. This requires a sampling time of approximately 20 milliseconds, and 2
If 0 to 300 mm 11 g is detected in 0 milliseconds, 14.00 to 20.0 ()0 pulses will be input to the counter.

Therefore, if we use the same counter and the same sampling time to measure absolute and relative values, then
at least 20,000 to 14,000, i.e. 6
, 000 pulses is required.

In view of the above, the present invention provides a waveform processing device that can reduce the number of bits of the counter even when measuring absolute values and relative values using the same counter, and can significantly shorten the sampling time for absolute values. is intended to provide.

(d) Means and operation for solving the problems As shown in FIG. 1, the waveform processing device of the present invention includes a pulse signal generating means l that generates a pulse signal of a frequency corresponding to the waveform level, and a counter 2 that receives and counts pulse signals from a pulse signal generating means; a first short period T1;
a second period T2 which is longer than the first period;
Absolute value conversion data storage means 4 for storing absolute value data of a waveform corresponding to the output value of the counter counted during the period, and deriving the corresponding absolute value from the specific output of the counter;
Relative count value storage means 5 (5a
, 5b), a difference value calculation means 6 for calculating the difference value between the current count value and the previous count value stored in this relative count value storage means, and the difference value and absolute value calculated by this difference value calculation means. Relative value calculation means 7 that calculates a relative value based on a determined constant
It is composed of.

This waveform processing TTI! In the device, a pulse signal generating means 1 generates a pulse signal with a frequency corresponding to the waveform level, and
During a short period T, this pulse signal is applied to the counter 2 via the gate means 3 and counted. Then, in accordance with the counted value of the counter 2, the absolute value of the waveform level is derived from the absolute value conversion data storage means 4.

Further, the pulse signal from the pulse signal generating means 1 is
is added to the counter 2 via the gate means 3 during a period T2 which is longer than the period T, and this is repeated, and each count value is stored in the relative count value storage means 5. Subsequently, the difference value between the current count value and the previous count value stored in the relative count value storage means 5 is calculated by the difference value calculation means 6, and the relative value calculation means 7 is calculated from this difference value and a constant determined by the absolute value. The relative value of the waveform is calculated.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 2 is a block diagram of an electronic blood pressure monitor in which the present invention is implemented. In the figure, a pressure sensor 11 includes a cuff that is pressurized and depressurized by a pneumatic system, and is capable of applying a pressure signal corresponding to the cuff pressure to a pulse signal generator 12. The pulse signal generating section 12 is constituted by an oscillator including a CR, and the capacitance of a capacitor C, for example, changes depending on the cuff pressure from the pressure sensor 11, and the oscillation frequency changes accordingly. The output pulse signal of the pulse signal generating section 12 is manually counted by the counter section 13, and the counted value is taken into the CPU 15 via the input/output interface 14.

Further, the timing of resetting the counter section 13, starting counting, stopping counting, etc. is regulated and controlled by the CPU 15.

The K sound sensor 16 extracts the Korotkoff sound signal, amplifies the signal with an amplifier 17, and inputs it to the CPU 15 via the input signal generator 18. The human power device 19 includes key buttons for instructing the start of measurement and instructing rest and exhaustion. The memory 20 also stores data for determining the absolute value or relative value of the cuff pressure, or other data, as will be described later. Further, the display 21 displays the measured systolic blood pressure, diastolic blood pressure, pulse wave, etc.

The counter section 13 has one
Flip-flops 131a, 131b1 and 0 J-
..., 131 L latch cell 132a.

When a pulse signal is input to the input terminal 133, a clear signal is input from the input terminal 134, and a latch command is input to the input terminal 135, a flip-flop is input to J-. 131a, 13
Each bit output of 1b, . . . , 131j is latched into a latch cell 132a, 132b, . Further, when an output control signal is input to the input terminal 136, the U-nochi cells 132a, 132b, . . .
・Each output of the bow 32j is output terminal 137a, 137b,・
−・−・・137 j.

Overall Operation> Next, the overall operation of the electronic sphygmomanometer according to the embodiment will be described with reference to the flowchart in FIG.

When the power switch is turned on, operation starts, and first,
Initialization is performed at the start (step 5T1)
), then the process moves to cuff pressure display, cuff pressure absolute pressure detection, and cuff pressure relative pressure detection processing (Sr1, Sr3.5T4). Detection of the absolute and relative pressure of the cuff pressure at this stage is performed to determine whether or not the cuff is being inflated, and whether or not the inflating has ended, but the processing procedure is to detect the absolute pressure at the time of measurement. process·
Since this is the same as the relative pressure detection process, the details will be described later.

At Sr1, it is determined whether or not pressurization is in progress, but if the subject has not wrapped the cuff around the upper arm and started pressurization, this determination will be NO.
Therefore, the processes of ST2 to ST5 are repeated until pressurization is started.

When pressurization is started, the determination in Sr1 becomes YES, and then a pressurization end determination process is performed, that is, it is determined whether or not the pressure has been increased to a predetermined set blood pressure (Sr6.5T7). When the pressurized blood pressure reaches a predetermined set value, the determination of Sr7 becomes YES, and then initialization at the time of measurement (resetting registers, timers, etc., transition to slow exhaust, etc.) is performed (Sr1)
, and then enters the measurement processing routine.

First, display processing is performed in Sr9. In this process, "measuring" is initially displayed, but as the measurement progresses, the systolic blood pressure value, diastolic blood pressure value, average blood pressure value, cuff pressure, etc. are displayed. Next, it is determined whether 0.5 seconds have elapsed (S
TIO). The time measurement for this judgment starts from the time of initialization at the time of measurement, but from then on, every time the 0.5 second timer is reset after 2.0.5 seconds, the timer starts 1.
- to do. This indicates that sampling processing is performed every 0.5 seconds. Therefore, cuff absolute pressure detection (STII) is performed every time the determination becomes YES at 5 TIO, that is, every 0.5 seconds.

However, until 0.5 seconds have passed, the 5TIO judgment is N.
o, and then it is determined whether 30 milliseconds have elapsed. Then, the relative cuff pressure is detected every 30 milliseconds (ST12, ST13). Then, based on the detected relative cuff pressure, pressure pulse wave recognition processing is performed (
ST14), and detection processing of other parameters, such as Korotkoff sounds, is performed (ST15). While the Korotkoff sound is not detected, the process returns to ST9 through the blood pressure determination process at 5T15 and 5T16, and the determination No as to whether the process is completed at 5T17, and the processes from ST9 to 5T17 are repeated.

5T15, when the occurrence or disappearance of Korotkoff sounds is detected, the cuff pressure at the time of detection is set to the maximum m1 pressure and
The lowest blood pressure is set (ST16).

This determination method itself is already well known.

When the diastolic blood pressure is determined and, for example, a predetermined period of time has elapsed, it is determined that the measurement has ended (ST17), and the operation comes to an end.

<Absolute Pressure Detection Process> The cuff absolute pressure detection process in ST3 and 5TII in FIG. 4 described above will be explained with reference to the flowchart in FIG. 5.

When entering the absolute pressure detection routine, first, the counter of the counter section 13 is cleared (ST31), and after clearing, it is determined whether 2 milliseconds have elapsed (ST32).

Then, the counter counts the pulse signals from the pulse signal generator 12 until the determination at 5T32 becomes YES. When 2 milliseconds have elapsed since the counter was cleared, the determination of 5T32 becomes YES, the old number of clicks is stopped (S733), and the count value of the counter is read into the CPUI 5. FIG. 9 shows the correspondence between the cuff pressure detected by the pressure sensor 11, the pulse signal generating section 12, the signal oscillation frequency, and the count value of the counter section 13.

For example, assuming that the cuff pressure is 100 mn+Hg during slow evacuation (see Fig. 7), the oscillation frequency of the pulse signal generator 2 is 875,000 t (z
In 2 milliseconds, the output pulses are 1,749,
The counter consisting of 10 bits reaches the full value (1,023 in decimal notation) once, and then stops at a further count of 726. This count value 726 is read into the CPU 15. Then, from the count value of the counter, for example 726, determine the address of the cuff pressure conversion data in the table of the memory 20 (5T35), and read out the cuff pressure, for example 100mmt1g, corresponding to the count value from the table of the memory 20 (S
T36).

In the manner described above, the cuff absolute pressure is detected.

<Relative Pressure Detection Process> Next, the cuff relative pressure detection process in ST4.5T13 in FIG. 4 will be described with reference to the flowchart in FIG. 6.

When entering the relative pressure detection routine, the counter of the counter section 13 is cleared (S'["41). Then, it is determined whether 20 milliseconds have elapsed since the clearing (ST42).
). The counter counts the pulse signals from the pulse signal generator 12 until the determination in S T 4.2 becomes YES.

If 20 milliseconds have elapsed since clearing the counter, S
The determination in T4.2 is YES, the counting of the count is stopped (ST43), and the contents of the recording area M1 of the memory 20 up to that point are transferred to the storage area M2 (ST4).
4), the current count value of the counter is stored in the storage area M,
(ST45).

In the above absolute pressure detection, the period during which the counter counts the pulse signal is 2 milliseconds, whereas in this relative pressure detection process, the counting period is 20 milliseconds.
This is to achieve high resolution.

Next, the count value C1 of the current counter recorded in the memory 20 and the count value C2 of the counter counted during the previous sampling are respectively recorded in the area M.

read from M2, calculate the difference value C, -C2=R, and store it in the storage area M3 of the memory 20 (Sr46.5T4
7).

Now, the cuff pressure in area A of FIG. 7 is shown in FIG.
Assuming that the cuff pressure at the zero point before sampling is 102 mm and 11 g, the counter reaches its full value 17 times in 20 milliseconds at time C, and the count value when counting is stopped is 48. Furthermore, at this point, the counter reaches its full value 17 times in 20 milliseconds, and the count value is 41 when counting is stopped. Therefore, according to this example, 4l-48=-7 is calculated in 5T46,
A count difference value R=-7 is stored in the storage area M3.

In addition, the current point is F, and the cuff pressure at point F is 104.3 mm.
Hgs 1Cuff pressure at point E before sampling 1O4m
Assuming mHg, the full value is reached 17 times in 20 milliseconds at time E, and the count value when counting is stopped becomes 4 in decimal notation. Also, at the current point F, the counter reaches its full value 16 times in 20 milliseconds, and the count value when counting stops is 1,022 in decimal notation.
becomes. Therefore, in this example, 1022-
41018 is calculated, and the count difference value R=1 is stored in the storage area M.
018 is stored.

After calculating the count difference value R in 5T4G, successively, R>512
It is determined whether or not (Sr48). 512 is 2 of the count value 1024 which is the full value of the counter, and the difference value R is this 51
If it is larger than 2, it means that the number of full values is different by one. For example, the difference value between points E and F in Fig. 8 corresponds to this, and if the difference value R is smaller than 512, , means that the number of full values is the same; for example, 0 in Figure 8
The count difference value between point and point D corresponds to this.

As a result of the determination in 5T4B, if the difference value R is larger than 512, 1024 is subtracted from the counted difference value R to calculate the true difference value R (Sr49). In the case of points E and F in the above example, R=1018-1024=-6. If it is determined at 5T48 that R is smaller than 512, skip 5T49 and proceed to the next step.

Next to judgment NO1 in 5T4B or 5T49, Sr1
0, and it is determined whether R<-512.

This judgment is made when the cuff pressure is decreasing and the number of times the counter reaches the full value is different, R+10 at 5T51.
This is to perform the processing of 24-R.

For example, in Figure 8, the cuff pressure at point G is 104.3 mm.
Hg, assuming the cuff pressure at point H is 103.9 mmHg,
The counter is full value 16 times at G point and the count value is 1,022
Then, at point H, the full value is 17 times and the count value is 7, and the count difference value R is 7-1022=-1015. In this case, -1015+1024=9 is obtained for Sr11.

In addition, when it is rising like the said CD point and EF point, since R<-512 of course is not carried out, Sr11 is skipped and it moves to the next.

When the count difference value R is calculated in 5T46 to 5T51, this R is stored in the dividend storage area M4 (Sr52). Then, based on the current cuff pressure (absolute pressure), a corresponding divisor is read from the divisor storage table (see the following table) in the memo I720 and stored in the divisor storage area M.

(Leaving space below) Divisor memory table This divisor memory table shows how much the count value changes each time lmmHg changes depending on the cuff pressure level. It stores the change count value of .

In the examples shown in FIGS. 7 and 8 above, the cuff pressure is between 90 and 10 mmHg, so the divisor is -22.

Once the divisor is obtained with 5T53, the cuff pressure change value can be calculated from the following formula:
That is, relative pressure ΔPC is detected (ST54).

ΔPC=Dividend/Divariance In the above example, at points C and D, ΔPC=-7/-22= 0.3 mml1g At points D and F, ΔPC=-6,/22'; 0.3mm1g
At point G and point H, ΔPC=-9/-22=0.4mm11g.

In the manner described above, the cuff relative pressure is detected.

Note that the divisor table cannot be used unless the absolute value of the cuff is detected first. Therefore, 1 mm Hg
If you fix the hit count to a constant value (for example, 2
2) The count value per 1 mm 11 g varies from 0 to 300 mm 11 g from 14 to 29 in the above table. Therefore, if it is fixed at 22, the g height will include an error of 140%. However, within the range of close cuff pressure values (5
0mmtlg), and when comparing the sizes, the error is sufficiently small, less than 10%.

Therefore, in the pressure pulse wave image reconstructed from the values obtained by relative pressure detection in the above embodiment, the variation in the cuff pressure value of the normal pressure pulse wave is 1.
Since it is less than 0 mm and 11 g, it depends mostly on the resolution of sampling.

In the above embodiment, the case of detecting the absolute pressure and relative pressure of an electronic blood pressure monitor was used as an example, but the present invention is not limited to electronic blood pressure monitors, and can be applied to the case of detecting the absolute value and relative value of a waveform. Broad (applicable)

(F) Effects of the Invention According to this invention, in order to detect the absolute value and relative value of the waveform level, the pulse signal generating means generates a pulse signal with a frequency corresponding to the waveform level, and this pulse signal is The absolute value is obtained in relation to the count values of the short first period and the long period, and the relative value is obtained in relation to the difference between the count values of the second period. , the number of bits corresponding to the difference value is sufficient, and the number of bits of the counter can be reduced. Furthermore, since it is not necessary to take the accuracy of relative value calculation into account when calculating absolute values, the sampling time can be significantly shortened.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of the present invention, and FIG. 2 is a circuit block diagram of an electronic blood pressure monitor showing an embodiment of the present invention.
Fig. 3 is a circuit block diagram showing a specific example of the counter of the electronic blood pressure monitor, Fig. 4 is an overall flow diagram for explaining the operation of the electronic blood pressure monitor, and Fig. 5 is an absolute diagram of the same flow diagram. FIG. 6 is a flowchart specifically showing the pressure detection processing routine. FIG. 7 is a flowchart specifically showing the relative pressure detection processing routine in the same flowchart. FIG. FIG. 8 is an enlarged view of part A in FIG. 7, and FIG. 9 is a diagram showing the correspondence between cuff pressure, oscillation frequency, and counter count value in the electronic blood pressure monitor. . ■ = Pulse signal generation means, 2: Counter, 3: Gate means, 4: Absolute value change data recording tα means, 5: Relative count value recording jQ means, 6: Difference value calculation means, 7: Relative value calculation means. Patent applicant Tateishi Electric Co., Ltd. Agent
Patent Attorney Shigeru Nakamura Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] (1) A waveform processing device that detects the absolute value and relative value of a waveform whose level changes over time, and includes a pulse signal generating means that generates a pulse signal with a frequency corresponding to the waveform level; a counter that receives and counts pulse signals from the means; and a counter that is selectively opened during a first short period and a second period that is longer than the first period; gate means for guiding a pulse signal to the counter; and absolute value data of the waveform corresponding to the output value of the counter counted during the first period is stored, and the corresponding absolute value is derived from the specific output of the counter. Absolute value conversion data storage means; Relative value storage means for chronologically storing each output value of the counted value of the counter each time the second period arrives; and Storage in the relative count value storage means. A waveform processing device comprising: a difference value calculation means for calculating a difference value between the current count value and the previous count value; and a relative value calculation means for calculating a relative value based on the difference value and a constant determined by the absolute value.