JPH0131203Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electrocardiogram signal recording device that records an electrocardiogram signal together with a phonocardiogram signal or a His bundle electrocardiogram signal having a higher frequency component than the electrocardiogram signal using a direct galvanometer.

Generally, a thermal writing recorder using a direct-writing galvanometer is used as an electrocardiograph from the viewpoint of operability and cost. Therefore, for example, when recording a phonocardiogram signal, an envelope modulated at a modulation frequency of around 80Hz, which is the upper limit frequency of the galvanometer response, is recorded. There was a drawback that the phonocardial waveform could not be depicted using amplitude.

Therefore, the present invention is an electrocardiogram signal recording device that can collect data of other biological signals with high frequency components that should be recorded together with electrocardiogram signals at the minimum necessary sampling rate, and can draw them faithfully and with a larger amplitude using a direct-writing galvanometer. The purpose is to provide

Next, the present invention will be explained based on the illustrated embodiments.

In the electrocardiogram signal recording device shown in FIG.
and an A/D that digitizes the analog output.
A converter 2, a memory 3 that stores digitized electrocardiogram signals, and a direct-writing galvanometer 4 that converts the signals read from the memory into analogs and draws waveforms on recording paper with a hot writing pen or the like constitute an electrocardiogram recording section. are doing. Also, a peak hold circuit 1 holds the lowest value and the highest value during the sampling period of the phonocardiogram signal in an analog manner.
0 and 10', and an A/D converter 1 that digitizes the held maximum value and minimum value signals, respectively.
1, 11', and memories 12, 12' for storing the digitized maximum and minimum values, respectively;
A data creation circuit 13 outputs the maximum value and minimum value signals read from this memory and interpolated value signals calculated based on these maximum and minimum values, and the output signal of this data creation circuit 13 is a selection circuit 14 that cyclically selects the value, minimum value, interpolated value, and maximum value in the order of value, and another direct galvanometer 15 that writes directly on the recording paper by converting the selection output into analog and supplying it to the attached galvanometer. constitutes the phonocardiogram recording section. The data creation circuit 13 sets the maximum value and the minimum value to 3, for example.
In order to perform point interpolation, holding units 20, 20' for the highest value signal H and lowest value signal L and the interpolated value signal
It includes calculation units 21, 22, and 23 that calculate 3H+L/4, H+L/2, and H+3L/4.

The frequency of the sampling pulse a of the electrocardiogram signal and the phonocardiogram signal is a frequency that matches the frequency component of the phonocardiogram signal, that is, in order to hold the highest and lowest values, the frequency is set to at least 300 Hz, which corresponds to the maximum frequency component; The frequency of the read pulse b of the memories 3, 12, 12' is set to be 35 Hz, for example, which is sufficiently low compared to the upper limit response frequency of the galvanometers belonging to both recording sections, and the frequency of the read pulse b of the selection circuit 15 is set to 35 Hz.
The frequency of 8 is the number of output signals of the data creation circuit 13.
The frequency is set to 35×8Hz corresponding to each individual.

The operation is as follows.

The electrocardiogram signal detected by the inductive electrode is processed by removing the in-phase signal, filtering, amplifying, etc.
The signal is held in the sampling hold circuit 1 in synchronization with the sampling pulse a, and is digitized in the A/D converter 2. The memory 3 stores the digitized electrocardiogram signal for a predetermined time while shifting the address for each sampling pulse a.

On the other hand, the highest value H and lowest value L of the phonocardial signal are held in peak hold circuits 10 and 10' at each sampling period, and the A/D
Memories 12, 1 through converters 11, 11'
2' and stored. At this time, the sampling frequency is 300Hz, and in order to hold the highest and lowest values for each sampling, it is possible to accurately store frequency components up to 300Hz without missing envelope information, which is especially required for phonocardiograms. can. As a result, sufficient timbre data of heart sounds can be stored without increasing the sampling rate or memory capacity.

When reproducing the electrocardiogram signal and the phonocardiogram signal, the memories 3, 12, 12' are switched to the read mode by the R/W signal and the read pulse b is supplied.
The electrocardiogram signal is sequentially read out from the memory 3 at 35 Hz, converted into an analog by a direct galvanometer 4, and the associated galvanometer is driven to draw the waveform of the electrocardiogram signal for a predetermined period of time.

On the other hand, the memories 12 and 12' store sampling values H ₁ , H ₂ , H _{3 .} . . and L ₁ , L ₂ , L ₃ . pulse b
are read out in order. First, the holding unit ₂₀ ' latches the lowest value _L0 at L0 of the lowest value latch pulse d,
The lowest value L ₀ is selected at the selection position of the selection circuit 14 and the direct writing type galvanometer 15 is caused to draw corresponding to this value. Immediately before this selection pulse c is supplied, the highest value latch pulse e is applied.
At _H1 , the holding unit 20 latches the highest value _H1 and causes the calculation units 21 to 23 to calculate interpolated values for _H1 and _L0 . Therefore, each time the selection circuit 14 advances the selected position, the interpolated value is
Select and draw H ₁ +3L ₀ /4, H ₁ +L ₀ /2, and 3H ₁ +L ₀ /4. When the selection position is reached, the highest value H ₁ is selected, and just before this, the holding unit 20' latches the lowest value L _1. Therefore, when the selection position advances as follows, 3H ₁ +L ₁ /4, H ₁ Select +L ₁ /2 and H ₁ +3L ₁ /4 in order. In this way, the direct galvanometer 15
is interpolated every time the selection circuit 14 cyclically steps forward, and selects the lowest value L ₀ , the highest value H ₁ , L ₁ , H ₂ , L ₂ , H ₃ . . .
Draw them in order. Therefore, the drive input supplied to the direct galvanometer 15 is 35Hz,
Sufficient amplitude can be drawn with a normal input level, and conversely, when the drive frequency becomes low, the drawn waveform tends to follow the input signal waveform accurately and become step-like. However, the interpolation according to the present invention allows for a faithful phonocardiogram. Signal waveforms can be drawn. Since the frequency component of the electrocardiogram signal is lower than that of the phonocardiogram signal, the staircase wave is less accurate than the latter, but interpolation can be performed in a similar manner if necessary.

Note that the A/D converters 11, 11' and the memories 12, 12' can be shared and operated in series during each write and read operation. memory 3,
12 and 12' can also be RAM. The memories 12, 12', the data creation circuit 13, and the selection circuit 14 can be replaced with a microcomputer 30 programmed in ROM to have the corresponding circuit functions as shown in FIG. 3, and according to the flowchart shown in FIG. make it work.

FIG. 5 shows a modification of the data generation circuit 13 according to FIG. 1. When the phonocardial signal rises over many sampling periods as shown in FIG. This is smoothed because it has a sawtooth shape as shown in the figure. That is, each part 20, 20', 21 to 2 of the data creation circuit 13 in FIG.
A holding unit 31 that latches the highest value of the immediately preceding sampling period for 3, and a holding unit 31 that latches the highest value of the immediately preceding sampling period for 3;
A comparison section 32 that compares the lowest value of 0', a switch 33 that is switched by a coincidence signal generated when both comparison inputs match, and a holding section 34 that latches the signal selected by this switch 33 are added. ing. As a result, when the lowest value L _o of each cycle matches the highest value H _o-1 of the immediately preceding sampling cycle, it is replaced with the highest value H _o and output and calculated.
and is depicted (Figure 6h). Note that this circuit function can also be realized by the microcomputer 30.

As described above, when drawing waveforms of a normal electrocardiogram signal and another biological signal with a higher frequency component than this signal using a direct galvanometer whose response frequency upper limit is lower than that of the other frequency component, both signals can be Sample at frequency and store in memory,
During recording, both signals are read from the memory at a sufficiently low frequency corresponding to the frequency characteristics of the galvanometer, and by interpolating biological signals with particularly high frequency components, the galvanometer reads out higher frequency components along with normal electrocardiogram signals. It becomes possible to depict biological signals with large amplitude and with high fidelity. Regarding the simultaneous recording of the phonocardiogram signal or the His bundle electrocardiogram signal, it is no longer necessary to modulate the envelope of these signals at a frequency near the upper limit response frequency of the galvanometer.

[Brief explanation of drawings]

FIG. 1 shows an example of the circuit configuration of an electrocardiogram signal recording device according to an embodiment of the present invention, FIG. 2 shows waveforms of various parts thereof, FIG. 3 shows a modification of the circuit shown in FIG. 1, and FIG.
A flowchart explaining the operation of the circuit through diagrams,
FIG. 5 shows a modification of the circuit shown in FIG. 1, and FIG. 6 shows an explanatory diagram of the circuit shown in FIG. 4, 15... Direct galvanometer, 14...
selection circuit.

Claims (1)

[Scope of utility model registration request] A circuit that samples and holds an input electrocardiogram signal at a first frequency corresponding to another biological signal with a higher frequency component that should be recorded together with the electrocardiogram signal, a memory that stores the electrocardiogram signal held by this sampling and hold circuit, and A direct galvanometer is supplied with an electrocardiogram signal read from a memory at a second frequency sufficiently lower than the upper response frequency of the galvanometer to which it belongs, and the lowest and highest values of the other biological signal are read at the first frequency. a peak hold circuit for holding, a memory for storing the lowest value and the highest value, and outputting the lowest value and highest value signals read from the memory at the second frequency and an interpolated value signal calculated from these values. a data generating circuit that cyclically selects the lowest value signal, interpolated value signal, and highest value signal output from this data generating circuit; and another direct galvanometer that is supplied with the output signal of this selecting circuit. An electrocardiogram signal recording device comprising: