JPH0344A - R-wave detecting circuit for electrocardiogram - Google Patents

Abstract

PURPOSE:To perform accurate detection of R-liquid by a method wherein a reference voltage obtained by a peak hold circuit to output a reference voltage changed according to the peak value of an output from a proportional adding circuit is compared with an output from the proportional adding circuit. CONSTITUTION:A proportional adding signal Eg is inputted at intervals of a given time, a peak value is held by a peak hold circuit 6 for a long time, and is obtained as an output Ec. The output Ec is applied on the gate of an FET serving as a variable resistance element 5, and when a resistance value is varied, a resistance ratio between the resistance value and resistance Rg is changed, and feedback control is applied on the voltage Ec by means of the output Eg. The voltage Ec is used as a reference voltage in a comparator monomulticircuit 7. The comparator monomulticircuit 7 compares the high-order reference voltage Ec with the output Eg from the proportional adding circuit, and an R-wave signal is detected and is obtained as a detecting pulse RDET. The reference voltage Ec in the comparator monomulticircuit 7 is a signal obtained based on a signal arrived one before the present signal Eg, feedback control is applied on the reference voltage, and an R-wave is detected in a constantly optimum state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an R-wave detection circuit in electrocardiogram waveform processing, and particularly to a highly accurate R-wave detection circuit.

(Prior Art) Conventionally, this type of R-wave detection circuit passes a specific guided portion (for example, the ■ lead) through a differential filter, extracts the R-wave component, and extracts the R-wave component.
R waves were detected by setting a fixed detection threshold.

(Problem to be Solved by the Invention) Since the detection level threshold in the conventional R wave detection circuit described above is set to a fixed value,
There is a drawback that no waves are detected at all, and that R waves near this set threshold value may or may not be detected depending on the conditions at that time, resulting in inaccurate detection of R waves.

(Means for Solving the Problems) An electrocardiogram R wave detection circuit according to the present invention receives each of three lead signals selected from the R lead of an electrocardiogram as input,
A differential absolute value circuit that processes differential absolute values, a proportional addition circuit that weights and adds the outputs of these differential absolute value circuits, and a peak hold that outputs a reference voltage that changes according to the peak value of the output of this proportional addition circuit. and a comparator that detects an R wave by comparing the reference voltage obtained by the peak hold circuit and the output of the proportional addition circuit.

(Example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an electrocardiogram R fluid detection circuit according to the present invention. In addition, FIG. 2 shows circuit examples of the differential absolute value circuits 1 to 3 in FIG. 1, and FIG.
A circuit example of the long-term peak hold circuit 6 in the figure is shown in FIG. 4, which is a signal waveform diagram of each part for explaining the embodiment of FIG. 1.

Now, to explain the operation of this embodiment with reference to FIG. Each of the signals is processed by differential absolute value circuits 1 to 3, which are absolute value circuits having specific characteristics. The obtained electrocardiographic waveforms m, v2. v, in the proportional addition circuit 4, for example, E,=A (E summer+0.
A weighted output E9 of 8Ev2+0°9Ev5) is obtained.

Here, A is a proportionality constant. This output E1 is a resistor R
F is connected in parallel and functions as a variable resistance element 5.
It is supplied to the source of ET and its resistance is varied. The resistance ratio between the resistance value changed in this way and the resistance R1 is the power supply +V (
(is divided, and a divided voltage Ec is obtained. In FIG. 4, the proportional addition signal E is inputted at predetermined time intervals, and the peak value is held by the long-term peak hold circuit 6, which is obtained as the output Ec. The obtained output E is applied to the gate of the FET as the variable resistance element 5, and when its resistance value is varied, the resistance ratio with the resistor R1 changes in the same way as above, and eventually the voltage Ec becomes Feedback control is performed by the output E. The obtained voltage Ec is used as a reference voltage in the comparator monomulti circuit 7. Here, lN5T is a signal for resetting the operation of the peak hold circuit 6. The comparator mono-multi circuit 7 compares the upper reference voltage EC and the output E of the proportional addition circuit to detect an R wave signal and obtain it as a detection pulse RDET.

The reference voltage Ec in the comparator monomulti circuit 7 is a signal obtained based on the signal that arrived one time before the current signal E, and this reference voltage is feedback-controlled to always detect the R wave in an optimal state. I will do it.

Figure 2 shows the differential absolute value circuit 1.2.3 in Figure 1.
As an example, FIG. 3 shows a long-time peak hold circuit 6.
An example of each is shown.

In the figure, IC1, IC2, and IC3 represent operational amplifiers, and Ql and Q2 represent transistors.

(Effects of the Invention) As explained above, the present invention adds the differential absolute values of the selected three-lead waveforms with predetermined weights, controls the on-resistance of the variable resistance element using the peak value of the added signal, and controls the reference voltage ( Since the threshold value) is optimally determined, the R level is low.
Even with waves, the reference voltage can be automatically set so that the detection sensitivity is proportional to the peak value. Therefore, there is an effect that highly accurate R wave detection becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the electrocardiogram R fluid detection circuit according to the present invention, FIG. 2 is a diagram showing an example of the differential absolute value circuit of FIG. 1, and FIG. 3 is a block diagram showing an example of the differential absolute value circuit of FIG. FIG. 4 is a diagram showing an example of the peak hold circuit 6, and is a diagram showing signal waveforms of the main parts of the block diagram of FIG. 1. 1.2.3... Differential absolute value circuit, 4... Proportional addition circuit, 5... Variable resistance element, 6... Long time peak hold circuit, 7... Comparator monomulti circuit.

Claims (1)

[Claims] A differential absolute value circuit receives each of the three lead signals selected from the R lead of the electrocardiogram as input and processes differential absolute values, a proportional addition circuit weights and adds the outputs of these differential absolute value circuits, and A peak hold circuit outputs a reference voltage that changes according to the peak value of the output of the adder circuit, and an R wave is detected by comparing the reference voltage obtained by this peak hold circuit with the output of the proportional adder circuit. An electrocardiogram R-wave detection circuit comprising: a comparator for detecting an electrocardiogram.