JPH0365970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel electrocardiogram R-wave detection device, and particularly to a device for detecting electrocardiogram R-waves extremely stably and easily due to heart rate coefficients.

Generally, as a biological signal, heart rate is one of the important parameters regarding cardiac function, along with electrocardiogram. Heart rate is usually measured at the same time as an electrocardiogram, and many attempts have been made to directly count heart rate from an electrocardiogram. In addition, in order to count heart rate from an electrocardiogram, the most basic method is to use the R wave. Conventionally, pulses are generated using this R wave, or R waves and T waves are generated using a square electrocardiogram. After expanding the amplitude ratio of , the R wave is extracted. Furthermore, since the rise of the R wave is determined by differentiation of the electrocardiogram, a differentiation circuit or the like is used to obtain confidence for heart rate counting. However, not only the amplitude ratios of R waves, P waves, T waves, etc. differ depending on each electrocardiogram, but also the amplitude of the T wave may be larger than the amplitude of the R wave, and the R wave may be negative. It may be a directional signal. Therefore, it is necessary to adjust the trigger level of the comparator for each waveform and to provide a rectifier circuit or the like. However, it is difficult to perform stable and accurate detection of R waves, and no definitive method has yet been developed.

Furthermore, in arrhythmia, the amplitude and occurrence of R waves are irregular, making it even more difficult to solve the problem.

In view of the current state of the present invention, the frequency component and amplitude of the R wave are used as parameters, and the R
An object of the present invention is to provide an electrocardiogram R wave detection device that can stably detect R waves.

In order to achieve the above object, the present invention has discovered that components other than R waves can be completely removed by using means having a center frequency in the R wave frequency band and controlling by frequency selection and amplitude. It has come to completion.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram of an embodiment of an electrocardiogram R wave detection device according to the present invention. In FIG. 1, an electrocardiogram input signal detected from a living body is supplied to a bandpass filter 1. In FIG. Bandpass filter 1 has the same center frequency as the frequency component of the R wave, and
Signal components consisting mainly of waves are extracted from the electrocardiogram.

The signal filtered by the bandpass filter 1 is supplied to half-wave rectifier circuits 2 and 6 and a comparator 3.
A series circuit of a capacitor 16, a resistor 17, and a discharge switch 7 is connected to the output terminal of the half-wave rectifier circuit 2, and a comparator 3 is connected for the next signal processing.
and 11 input terminals are connected, respectively. Note that the capacitor 16 has the function of holding the peak value of the output of the half-wave rectifier circuit 2. The comparator 3 inputs and compares the outputs of the bandpass filter 1 and the half-wave rectifier circuit 2 as described above, and generates an output while a peak is occurring, as shown in FIG.
The output of the half-wave rectifier circuit 6 is supplied to a capacitor 18 via a charging switch 7. While the charging switch 8 is connected, the capacitor 18 is charged to its peak, and this voltage is amplified by the buffer amplifier 10 and then supplied between the terminals of the dividing proportional resistors 19 and 20 to be divided. The output of the comparator 3 is given to a mono multivibrator 4 and a retrigger mono multivibrator 5. As a result, the mono-multivibrator 4 generates a pulse with a constant width as shown in FIG. 2D. Further, the retrigger mono-multivibrator 5 generates an output after a certain period of time has elapsed since the output of the comparator 3 disappears (FIG. 2G).

The mono-multivibrator 4 is used to provide an output to the AND circuit 12 to form a prohibition time so that multiple pulses are not generated within one beat. The comparator 11 compares the peak voltage of the R wave stored in the capacitor 16 with the voltage of the capacitor 18 divided by the resistors 19 and 20, and generates a comparison output as shown in FIG. . Comparator 1
1 is supplied to the AND circuit 12 together with the inverted output from the inverting circuit 21 of the mono multivibrator 4. The output of the AND circuit 12 is combined with the output of the retrigger mono multivibrator 5 to the OR circuit 13.
The voltage is supplied to the discharge switch 7 via the discharge switch 7, and the capacitor 16 is discharged by the operation of the discharge switch 7. Therefore, the comparator 11 instructs the discharge switch 7 to discharge until the value obtained by dividing the charging voltage of the capacitor 18 by the resistors 19 and 20 and the charging voltage of the capacitor 16 become equal. Note that the resistor 17 connected in series with the discharge switch 7 is inserted for the purpose of giving a slope to the discharge waveform of the capacitor 16 to prevent it from being triggered by the T wave included in the electrocardiogram waveform.

Further, the R-wave peak pulse output of the comparator 3 is supplied to a pulse rise detector 14, and a very narrow pulse output is formed as shown in FIG.
This pulse output is supplied to the discharge switch 9 and the capacitor 18 is discharged. Furthermore, the output of the pulse rising edge detector 14 is supplied to an inverting circuit 15. Therefore, charging switch 8 is connected to capacitor 1.
Since the charging circuit 8 is cut off, the previous R-wave peak voltage charged in the capacitor 18 is discharged without being affected by the output of the half-wave rectifier circuit 6. Further, after the pulse rise detector 14 generates a short pulse output, the discharge switch 9 is opened and the charging switch 8 is closed by the operation of the inverting circuit 15, so that the capacitor can be charged up to the peak voltage of the current R wave. Charging is performed at 18.

The above-described operation is repeated every time an electrocardiogram R wave arrives. In addition, in the end, mono multivibrator 4
The output is used as R-wave detection power.

As described above, the present invention captures the characteristics of R waves in an electrocardiogram from two aspects, frequency and amplitude, and thus exhibits the following effects.

1 The signal pre-processed with a bandpass filter is R
Since the signal is input to a comparator that detects the peak of the wave, peak detection is performed reliably.

2. Since the next trigger level is determined at the peak of the R wave one beat before, triggering by the R wave is possible over a wide range regardless of fluctuations in the electrocardiogram.

3. Since a bandpass filter is used in the initial input section of the device, a trigger output can be obtained regardless of the polarity of the R wave of the input electrocardiogram.

4. If there is no input electrocardiogram, the trigger sensitivity reaches its maximum after a certain period of time, so fluctuations in the electrocardiogram can be dealt with favorably and there is no malfunction.

5. T-wave triggers are difficult to detect, so there are no malfunctions caused by T-waves.

6. There is almost no occurrence of mistriggering due to waveform fluctuations due to body movements or myoelectric potential.

7 Accurate R-wave detection is possible even in arrhythmia with irregular amplitude and period.

8. Since the predetermined time is set to approximately the maximum cycle of the biological heartbeat cycle, emphasis is placed solely on preventing misdiagnosis due to noise, etc. within the range of normal heartbeat, taking individual differences into consideration.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of an electrocardiogram R wave detection device according to the present invention, and FIG. 2 is a waveform diagram showing waveforms of various parts of the same device. In the figure, 1 is a bandpass filter, 3 and 11 are comparators, and 4 is a mono multivibrator.

Claims (1)

[Scope of Claims] 1. Bandpass means for passing an electrocardiogram R-wave signal; Threshold holding means for maintaining a threshold voltage through charging and discharging operations; and when the R-wave signal that has passed through the bandpass means exceeds the threshold voltage. a comparison means for triggering an R-wave detection pulse signal by the above-mentioned signal; an output means for outputting a trigger of the output of the comparison means as an R-wave detection pulse; and a threshold voltage of the threshold holding means for passing through the bandpass means. charging means for charging to the peak value of the R-wave signal; dividing holding means for retaining a divided voltage of the peak value of the R-wave signal that has passed through the bandpass means; and dividing the threshold voltage after a certain period of time has elapsed from the trigger. An electrocardiogram R wave detection device characterized by comprising a discharging means for discharging to a voltage. 2. The electrocardiogram R wave detection device according to claim 1, wherein the threshold voltage is further discharged when the trigger does not occur for a predetermined period of time. 3. Claim 2, characterized in that the predetermined time is set to approximately the maximum cycle of the biological heartbeat cycle.
The electrocardiogram R-wave detection device described in 2.