JPH04329926A - Recorder/reproducer - Google Patents

Abstract

PURPOSE:To facilitate observation of an electrocardiogram waveform by reading out a digital data using a second address separated at a specified interval from the first address corresponding to a top as starting point to always display the electrocardiogram waveform at a fixed position on a screen. CONSTITUTION:An R waveform R and the top of the R waveform R, for example, maximum valve MAX is detected and an address corresponding to a pointer PT traced back by a specified pointer PTCO from a pointer PT of DWEH corresponding to the top is set as starting point of reading data. A data DWEH is read out continuously from the address as starting point and outputted to a liquid crystal display section 28 to display. Thus, in the display of an electrocardiogram waveform WEH, an R wave of the electrocardiogram waveform WHE1 of the first beat is always displayed at a fixed position on a screen, thereby facilitating the observation of the electrocardiogram waveform WEH.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording/reproducing apparatus, and particularly to a recording/reproducing apparatus suitable for displaying electrocardiographic waveforms.

0002

2. Description of the Related Art Holter electrocardiography is a method for collecting and analyzing electrocardiogram waveforms. Holter electrocardiography is a method of recording electrocardiographic waveforms in daily life using a portable recorder (tape recorder) over a long period of 24 hours or more, and analyzing the obtained electrocardiographic waveforms.

As a means of analysis, the recorded electrocardiographic waveform may be displayed on a monitor display and the electrocardiographic waveform may be observed.

0004

[Problems to be Solved by the Invention] Conventionally, there has been a display device in which when an electrocardiographic waveform is displayed for observation, the electrocardiographic waveform is displayed. In other words, since the display position of the electrocardiogram waveform cannot be fixed at a constant position, the electrocardiogram waveform is displayed in a continuous manner. As a result, there was a problem in that it was not easy to observe the electrocardiogram waveform.

[0005] Accordingly, an object of the present invention is to provide a recording/reproducing apparatus that can fix the display position of a particular waveform in an electrocardiographic waveform at a fixed position.

[0006]

[Means for Solving the Problems] The present invention provides a recording/reproducing device that stores digital data of an electrocardiogram waveform sampled with a sampling signal of a predetermined frequency in a memory, and reads and outputs the digital data from the memory. detect a vertex based on the digital data, designate the address of the digital data corresponding to the vertex as a first address, designate an address separated by a predetermined interval from the first address as a second address, The configuration is such that the digital data is read out using the address as a starting point.

[0007]

[Operation] Electrocardiographic waveform data sampled with a sampling signal of a predetermined frequency is stored in the memory. On the other hand, based on the above data, the R wave of the electrocardiogram waveform and the
The crest of the wave is detected.

[0008] The address of the memory where the data corresponding to the peak of the R wave described above is stored is defined as a first address, and the address that is a predetermined address away from the first address in the direction going back in time is defined as a second address. shall be. Then, data is read and displayed using the second address as a starting point.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. First, an electrocardiographic waveform recording device that can be applied to the present invention will be described.

Referring to FIG. 6, an electrocardiographic waveform recording device applicable to the present invention will be described. In the configuration of FIG. 6,
An analog signal taken out from one terminal of an electrode 1 attached to a human body (not shown) is supplied to a non-inverting terminal of a differential amplifier 2, and an analog signal taken out from the other terminal of the electrode 1 is converted into a differential signal. It is supplied to the inverting terminal of amplifier 2. This analog signal is an electrical signal output from the myocardium when the heart beats.

An analog signal SHR representing an electrocardiographic waveform is supplied from the differential amplifier 2 to a reference pulse insertion circuit 7 via a high-pass filter 5 consisting of a capacitor 3 and a resistor 4 and an amplifier 6. A bias voltage VBI is connected between resistor 4 and ground to keep the baseline level of the electrocardiogram waveform constant.
0 is placed.

In the reference pulse generation circuit 8, the reference pulse P
ST is formed and supplied to the reference pulse insertion circuit 7.

The reference pulse insertion circuit 7 inserts the above-mentioned reference pulse PST into the electrocardiographic waveform WEH. this is,
It is used for calibrating the gain of the recording device and as a reference for reading the level of the electrocardiogram waveform WEH.

[0014] As a result, an electrocardiographic waveform WEH is formed by superimposing the reference pulse PST. This electrocardiogram waveform W
An analog signal SHR0 representing EH is supplied to an A/D converter 11 via a low-pass filter 10.

[0015] In the A/D converter 11, the above-mentioned analog signal SHR0 is sampled at the timing of a sampling signal of a predetermined frequency supplied via the terminal 16, and converted into digital data. This digital data is supplied to the signal processing circuit 12. The sampling frequency in this A/D converter 11 is, for example, 2
The frequency is 50 Hz and the number of quantization bits is 12 bits.

In the signal processing circuit 12, the digital data supplied from the A/D converter 11 is subjected to processing such as addition of an error correction code, filtering, interleaving, channel coding, etc., to form a digital recording signal. Ru.

The digital recording signal is supplied to a magnetic head 14 via a recording amplifier 13, and is recorded on a magnetic tape 15 by the magnetic head 14.

An embodiment of the present invention will be described with reference to FIG. An ultra-small tape cassette 21 in which the electrocardiogram waveform WEH is digitized and recorded on magnetic tape is loaded into the data reproduction processing device 22. As a result, the electrocardiographic waveform WEH signal recorded on the magnetic tape and channel-coded is reproduced by the magnetic head.

The data reproduction processing device 22 is provided with a DSP, and after demodulating the original digital signal from the reproduced and channel-coded signal, the original digital signal is subjected to filtering, Signal processing such as error correction and deinterleaving is performed.

[0020] As a result, data obtained by digitizing the electrocardiogram waveform is reproduced, and this data is supplied as serial data to the display device 25 having a data holding function.

The display device 25 has a data holding function and is mainly composed of a decoder 26, a processor unit 27, a liquid crystal display section 28, a RAM 29, a ROM 30, and the like. Note that 31 is a bus. The above serial data is
First, the signal is supplied to the decoder 26.

The decoder 26 converts the above-mentioned serial data into 8-bit parallel data and generates an interrupt signal INT. From the decoder 26, data DWEH obtained by digitizing the electrocardiographic waveform WEH shown in FIG. 3 is supplied to the processor unit 27 at predetermined intervals. Furthermore, from the decoder 26,
Interrupt signal INT is supplied to processor unit 27 together with data DWEH.

The processor unit 27 outputs data DW at the timing when the above-mentioned interrupt signal INT is supplied.
EH is captured and recorded in the RAM 29, and an R wave R, which will be described later, is detected based on the data DWEH.

In the RAM 29, a memory area AR1 at addresses AD01 to AD0N shown in FIG. 2 is used like a ring buffer. Therefore, memory area area A consisting of addresses AD01 to AD0N of RAM29
1 for R1 under the control of the processor unit 27.
Multiple data DWE of electrocardiographic waveform WEH for horizontal scanning period
H and data representing the respective order of the data DWEH (hereinafter referred to as pointer PT) are recorded together.

The data DWEH of the electrocardiographic waveform WEH for one horizontal scanning period is, for example, two cycles of the electrocardiographic waveform WEH, for example, timings P01 to P03 shown in FIG.
A plurality of data D representing electrocardiographic waveforms WEH1 and WEH2 between
Pointers PT attached to each of WEH and data DWEH are recorded in the memory area AR1.

FIG. 3 shows P wave P, Q wave Q, R wave R, S.
One-beat electrocardiographic waveform WEH1, W consisting of wave S and T wave T
EH2 is shown.

Data DWEH for one cycle of the electrocardiogram waveform WEH is displayed between the timings shown in FIG. ~P02,P
02 to P03 are those that move in the left-right direction of the base line level LSL.

Then, the data DWEH of the electrocardiogram waveform WEH for the next two cycles and the pointer PT are stored at addresses AD11 to
It is recorded in the memory area AR2 consisting of AD1N.

By doing this, the address AD01
Two memory areas A: ~AD0N, AD11~AD1N
Even if one of R1 and AR2 is used as a write or read memory area, data can be held in the other memory area.

The method of recording the data DWEH in the RAM 29 is not limited to the above-mentioned example; for example, the number of cycles of the electrocardiogram waveform WEH in one horizontal scanning period may be set arbitrarily. . Further, the memory areas in the RAM 29 are not limited to AR1 and AR2 as described above, and any number and memory size can be set as necessary.

By the processing described later, R shown in FIG.
When the waveform R and the peak of the R waveform R, for example, the maximum value MAX, are detected, the address AD0i and pointer PTmax corresponding to the data DWEH of the maximum value MAX are read out. In this embodiment, the maximum value MAX is used as the apex of the R waveform R, but the present invention is not limited to this. For example, the R wave R as shown in FIG.
The minimum value MIN may be selected as the vertex to correspond to .

Next, the pointer PTm of the maximum value MAX
An address at a position that is a predetermined time, ie, a predetermined number of pointers, back from ax is read out as the read start position. In the example shown in FIG. 3, the address AD01 corresponding to the pointer PT01 located a predetermined pointer PTCO back from the pointer PTmax is read.

In the processor unit 27, the above address AD01 is set as the starting point for reading data DWEH. Then, according to a predetermined timing, from address AD01 as a reading start point to address AD0.
Data DWEH is read out continuously up to N and output to the liquid crystal display unit 28.

The liquid crystal display section 28 displays the addresses AD01 to AD01 supplied from the processor unit 27.
Based on the data DWEH up to 0N, for example, an electrocardiographic waveform WEH as shown in FIG. 3 is displayed.

The electrocardiographic waveform WE on this liquid crystal display section 28
In the display of H, the position of the R wave R of the electrocardiographic waveform WEH1 of the first beat is always fixed at a constant position on the screen. In other words, the position where data DWEH of pointer PT01 is displayed does not change, and the distance from pointer PT01 to pointer PTmax is defined as the value of predetermined pointer PTCO, so the distance from the left edge of the screen to R wave R is always constant. It is said that As a result, the electrocardiographic waveform WEH can be easily observed. Note that a CRT may be used instead of the liquid crystal display section 28.

Next, detection of the R wave R will be explained with reference to FIG. In step 101, the input electrocardiographic waveform WEH data is compared with a preset maximum value MAX. If the input data is greater than the maximum value MAX, the process proceeds to step 102; if the input data is less than the maximum value MAX, the process proceeds to step 103.

In step 102, the data of the input electrocardiographic waveform WEH is recorded as a new maximum value MAX, and the pointer of this data is recorded as time data corresponding to the maximum value MAX. After this, the process moves to step 105.

In step 103, the input data is compared with a preset minimum value MIN. If the input data is smaller than the minimum value MIN, proceed to step 104; if the input data is larger than the minimum value MIN, proceed to step 1.
Proceed to 09.

At step 104, the data of the input electrocardiographic waveform WEH is recorded as a new minimum value MIN, and the pointer of this data is recorded as time data corresponding to the minimum value MIN. After this, the process moves to step 105.

In step 105, the maximum value MAX and minimum value M of the data of the electrocardiogram waveform WEH held are determined.
The difference between IN and SUB [=|MAX −MIN |],
A comparison is made with a predetermined value [=α]. Waka, difference SU
If B is larger than the predetermined value α [SUB > α], the process proceeds to step 106, and if the difference SUB is smaller than the predetermined value α [SUB <α], the process proceeds to step 107.

In step 106, the difference SUB[=
A sign flag FS is set according to |MAX - MIN |], and a determination flag FCAL indicating the existence of a waveform that can be assumed to be an R wave R is set.

The sign flag FS is determined by the state of the R wave R, and when the R wave R is in the (+) direction as shown in FIG. 5A, the sign flag FS is, for example, [“1”].
Also, as shown in Figure 5B, the R wave R is (-
), for example, it is set as [“0”].

[0043] The determination possible flag FCAL is set in step 1.
When the value reaches 06, [="1"] is automatically set. After this, return to the main routine.

On the other hand, in step 107, the electrocardiogram waveform W
Time data T corresponding to the maximum value MAX of EH data
max and the minimum value MIN of the electrocardiogram waveform WEH data
The difference between the time data Tmin corresponding to TSUB [=|
Tmax −Tmin |] is compared in magnitude with a predetermined time value T0.

If the difference TSUB is larger than the time value T0 [TSUB > T0], the process proceeds to step 108, and if the difference TSUB is smaller than the time value T0, the process proceeds to step 108.
At SUB <T0>, the process ends and returns to the main routine. This is a step to prevent the T-wave T from being mistakenly selected as the R-wave R when the difference TSUB is too large, as in the case of the T-wave T.

In step 108, the maximum value MAX and minimum value MIN of data DWEH and time data Tmax are determined.
and Tmin, difference TSUB, determination possible flag FC
Clear all AL etc. After this, return to the main routine.

Up to the above step 106, the data D
The maximum value MAX and minimum value MIN of WEH, time data Tmax and Tmin, and sign flag F
S, flag FCAL, etc. are set and held.

In this state, new data [this data is smaller than the maximum value MAX and smaller than the minimum value MIN]
] is entered into the processing routine shown in FIG. 4, the process proceeds to step 109 via steps 101 and 102.

In step 109, the determination possible flag F
A decision is made regarding the CAL. If the determination possible flag FCAL is [="1"], there is a waveform that can be assumed to be an R wave R, and the process proceeds to step 110. Also, if the determination possible flag FCAL is [="0"
], then there is no waveform that can be assumed to be R wave R, so
It is determined that noise has been mixed in, and the process returns to the main routine.

In step 110, the time data Tmax corresponding to the maximum value MAX of the data held is
and the time data Tmi corresponding to the minimum value MIN of the data
Difference of n TSUB [=|Tmax −Tmin |]
and predetermined time values T1 and T2 are compared in magnitude.

If the detected waveform is an R wave R, the pulse width of the R wave R must be within a certain time range, so this point is checked. In other words, the difference T
SUB is within the range of time values T1 and T2 [T1<TSUB
<T2>, it is determined to be an R wave R and the process proceeds to step 111.
If the difference TSUB is not within the range of time values T1 and T2, it is determined that noise has been mixed in, and the process proceeds to step 114.

In step 111, the sign flag FS
will be judged. As mentioned above, the R wave R is (+
) sign flag F of [“1”] when standing in the direction
S is set, and when the R wave R is in the (-) direction, a sign flag FS of [“0”] is set. Therefore, when the sign flag FS is [“1”], the process proceeds to step 112, and the sign flag FS is [“0”].
”], the process advances to step 113.

In step 112, the R wave R standing in the (+) direction as shown in FIG. 5A is selected. After this, the process proceeds to step 114.

In step 113, the R wave R standing in the (-) direction as shown in FIG. 5B is selected. After this, the process proceeds to step 114.

In step 114, the sign flag FS
, the determination enable flag FCAL, etc. are all cleared, the R wave R is selected, and then the process returns to the main routine.

In this embodiment, the R waveform R and the apex of the R wave R, that is, the maximum value MAX or the minimum value MIN
is detected, and the address AD01 corresponding to the pointer PT that is traced back by a predetermined pointer PTCO from the pointer PT of the data DWEH corresponding to the vertex is set as the starting point of data reading, and the data is read continuously from address AD01 as the starting point to address AD0N. Read data DWEH automatically,
Since it is output and displayed on the liquid crystal display section 28, the liquid crystal display section 28
In the display of the electrocardiographic waveform WEH, the R wave R of the electrocardiographic waveform WEH1 of the first beat is always displayed at a fixed position on the screen, making it easy to observe the electrocardiographic waveform WEH. .

In this embodiment, an electrocardiogram waveform is used as an example, but the present invention is not limited to this, and other narrowband, low-frequency biological signals such as myoelectric waveforms, electroencephalograms, etc. It can also be applied to

[0058]

Effects of the Invention According to the recording/reproducing apparatus according to the present invention, an R wave in an electrocardiogram waveform and the peak of the R wave are detected, and the address of digital data corresponding to the peak of the R wave is detected. 1 address, and an address that is a predetermined address away from the first address in the backward direction in time is set as a second address, and digital data representing an electrocardiogram waveform is read out and displayed using the second address as a starting point. Therefore, there is an advantage that the position of the electrocardiogram waveform can always be displayed at a fixed position on the screen, and as a result, the electrocardiogram waveform can be easily observed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electrocardiographic waveform display device showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the usage status of RAM.

FIG. 3 is an explanatory diagram showing an electrocardiographic waveform.

FIG. 4 is a flowchart for detecting an R wave R.

FIG. 5 is an explanatory diagram showing the state of an R wave R corresponding to a sign flag.

FIG. 6 is a block diagram showing an example of a recording device applicable to the present invention.

[Explanation of symbols]

27 Processor unit 29 RAM WEH Electrocardiographic waveform DWEH Data PT, PTmax, PT01 Pointer MAX
Maximum value MIN Minimum value

Claims (1)

[Claims] 1. A recording/reproducing device that stores digital data of an electrocardiogram waveform sampled with a sampling signal of a predetermined frequency in a memory, reads out the digital data from the memory, and outputs the digital data, detect a vertex, designate the address of the digital data corresponding to the vertex as a first address, designate an address separated by a predetermined interval from the first address as a second address, and start the second address. A recording/reproducing device characterized in that the digital data is read out as a point.