JPS5815840A - Hemomanometer - 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 The present invention relates to an electronic blood pressure monitor that detects the Korotkoff sound (CK sound) using a microphone (K sound sensor) and digitally displays the systolic and diastolic blood pressure.

In general, the loudness of sound varies from person to person, and even within the same person, it varies depending on the time of day or physical condition. However, with conventional electronic blood pressure monitors, the sound detection sensitivity is constant, so for people with loud K sounds, the blood pressure may be higher than the actual blood pressure, and for people with soft sounds, the blood pressure may be lower than the actual blood pressure. It had the disadvantage of being measured. In addition, most of the sound sensors in the blood pressure monitor itself have characteristics that change with temperature, and furthermore, there are variations in temperature characteristics, so there is a drawback that complete compensation cannot be achieved under fixed temperature compensation conditions.

The present invention has been made to solve the above problems, and focuses on the fact that the magnitude of blood vessel noise is generally approximately proportional to the volume of the sound. By controlling the sound detection sensitivity, the purpose is to offset variations in sound volume and changes in the output due to the temperature of the sound sensor as described above, and to always measure blood pressure accurately. It is.

An embodiment of the present invention will be described in detail below based on the drawings. FIG. 1 shows a block diagram of the electronic blood pressure monitor of the present invention, where fil is a pressure sensor, the output voltage of which is amplified by a differential amplifier (2), and the pulse sound is detected by a p-wave device 131. do. In other words, when the signal voltage obtained by amplifying the output of the F wave device (3) with the amplifier (4) exceeds the reference voltage v1, the voltage comparator (
The output of step 5) is inverted, and a pulse representing the pulse sound detection interval is obtained. Pulses are outputted from the inverter (6) only in sections where no pulse sound is detected and are input to the AND gate (9). (7) is a circuit that detects that the cuff pressure is being reduced, and when the cuff pressure is started and the sound input is ready, the output of path (7) in this pressure reduction detection diagram is reversed and the AN
Open D gate (9). In this state, when the pulses of the above-mentioned pulse sound pause period are inputted to the counter decoder circuit 1to) of the analog multiplexer through the AND gate (9), the analog game (16a)(
16kl)... are opened, and the output voltage of the integrator 05) is sequentially taken into the memories (17a) (17t)). On the other hand, the filter (
The sound component extracted by 1'4 is amplified by amplifier 01, then rectified by a full-wave rectifier (14), and this output signal is applied to a voltage comparator (19) and an integrator. Smoothed by Of9. The capacitor of this integrator (I [9) is discharged by a switch during the pulse sound detection period, so that only the noise voltage during the pulse-free period is integrated.The output voltage of this integrator (151 is It represents the noise level in each section, and the noise level for each section is sequentially passed through the analog gates (16aX16kl)... and latched into the respective memories (17a) (17kl).Of course. This memory device (17ri is 1
Although the purpose of the present invention can be achieved with just the circuit, in this embodiment, the average value circuit θ barrel 1: yaw)"rll[By taking the average value of the circuit, the influence of sudden fluctuations in the noise level can be prevented. Figure 2 shows the simplest example of a specific circuit, in which capacitors C7 and C4 are used as each memory (17a to 07d), and an average value circuit (+
8) are analog games) (16b) to (16(
It consists of switches at) and sd that are closed immediately after the switch 1) is opened. The output voltage of the average value circuit is used as the reference voltage v2 of the voltage comparator H, and when the output voltage of the other input of the voltage comparator, that is, the full-wave rectifier 0<, exceeds this threshold value v2, the voltage comparison is performed. The output of the first K sound detection circuit (8) is inverted and the first sound is detected by the first K sound detection circuit (8).This first K sound detection output causes the average value circuit (181
is held, and the average value of the noise level at this time is used as the threshold value v2 until the end of the measurement. According to this configuration, "the newest 4th sound until the 1st x sound is detected"
Since the noise level for the section is stored, the noise level at the time of measurement can be compensated with extremely high accuracy.

However, in the above embodiment, the sound detection threshold set in the comparator is changed depending on the noise level, but the reference signal set in the - comparator H is kept constant, and the preamplifier (+:1
The gain may be changed depending on the noise level. When we say that the threshold value is relatively changed in the claims, we mean to include this point.

The present invention is configured as described above, and can compensate for individual differences in the loudness of the K sound and variations in the temperature characteristics of the sound sensor by simply adding a few circuits to a conventional electronic blood pressure monitor.
This makes it possible to measure blood pressure correctly.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of the electronic blood pressure monitor of the present invention, and FIG. 2 is a specific circuit diagram of the main parts of the same. +11 is a pressure sensor,
(2) is a differential amplifier, (3) is a filter, (4) is an amplifier, (5) is a voltage comparator, (6) is an inverter, (7) is a cuff pressure reduction detection circuit, (8) is the first K sound detection circuit, (9) is an AND gate, (lO) is a counter decoder circuit, (1
1) Hanion Sunsa, [12) G-iF wave device, Oa1gt
(14) is an aftereffect rectifier, (15) is an integrator, θ is an analog multiplexer, (16a) to 06(1) are analog gates, (t7a) to 07d) are memory devices, (1
8) is the average value circuit, (+9) is the voltage comparator, and Oka is the switch.

Claims (1)

[Claims] - In an electronic blood pressure needle that has a pressure sensor that detects cuff pressure and a sound sensor that detects Korotkoff sounds (hereinafter referred to as sounds), a P-wave device detects pulse sounds from the output of the pressure sensor, and The noise level in the blood vessel is detected by averaging the output of the sound sensor in the interval where the K sound is not detected, and the threshold for K sound detection is changed relatively in conjunction with the noise level. blood pressure monitor.