JP3035684B2 - Biological signal processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a Holter monitor which can record an electrocardiogram for a long time, and has a data compression ratio corresponding to the information amount of a noise data portion of a biological signal. The present invention relates to a variable biological signal processing device .

[0002]

2. Description of the Related Art Conventionally, a Holter electrocardiograph which is worn on a subject and records an electrocardiogram in a living activity uses a magnetic tape as a medium for recording electrocardiogram data. Such a Holter electrocardiograph using a magnetic tape has the device worn on the body for 24 hours or more, and is relatively poor in portability because the device is relatively large.

Further, since recording is performed by running the magnetic tape at a low speed in order to perform long-time recording, the frequency characteristics are deteriorated, and it is difficult to record high-quality electrocardiogram data. In order to improve this, that is, to improve portability and frequency characteristics, recent Holter electrocardiographs perform digital recording using a semiconductor memory for recording electrocardiogram data.

In such a Holter electrocardiograph using a semiconductor memory, data compression is required to record a huge amount of 24-hour electrocardiogram digital data. Such data compression is also necessary when an electrocardiograph that records electrocardiogram data of about several tens of seconds and data of a large number of subjects are made into a database, or when data is transferred via a communication device.

Various data compression methods have been proposed. This method is roughly divided into two,
One of them is a method (reversible method) in which original data can be faithfully reproduced without causing data distortion due to compression. Another method is a method (irreversible method) in which distortion occurs due to compression and the original data cannot be completely reproduced.

The former is not limited to electrocardiogram signals, and is a general data compression method. For example, there is an encoding compression method. In this method, although data is completely stored, the compression ratio is small and practically insufficient. is there. Therefore, the latter method is mainly employed as a data compression method for electrocardiogram signals, and various methods such as the AZTEC method and the SAPA method have been proposed as methods for realizing a high compression ratio with little data distortion.

When such data compression is performed, there is a reciprocal relation between the compression ratio and the data distortion in any method. That is, if a high compression ratio is achieved, the data distortion increases, and if the data distortion is reduced, the compression ratio decreases. Further, since the number of waveforms and the peak value in the electrocardiogram data fluctuate on the time axis, the amount of information and the redundancy of the data generally change significantly. For this reason, it is necessary to increase the compression ratio in the data portion where the data redundancy is large, and to decrease the compression ratio in the data portion where the data redundancy is small. Therefore, the compressed data becomes variable length data.

When a digital long-term electrocardiograph is formed using a digital information recording medium such as a semiconductor memory or a small hard disk, the recording capacity of the digital information recording medium is constant, and the electrocardiogram collection time is usually 24 hours. And 4
A certain period that is clinically and physiologically significant, such as 8 hours, is required.

[0009]

As described above, in the prior art, a sufficiently high compression ratio is set with a margin, and recording is performed at the expense of data distortion. In addition, 24
A method of stopping recording of electrocardiogram data before reaching a target time such as time or 48 hours, and a method of stopping recording of one side channel halfway in the case of multiple channel (for example, two channel) recording. All have practical problems.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks in the prior art, in which the compression efficiency of ECG data is improved, and the ECG data is transferred to a relatively small and low-capacity digital information recording medium. It is an object of the present invention to provide a biological signal processing device that improves recording efficiency and enables long-time recording with high accuracy.

Another object of the present invention is to provide a biological signal processing apparatus in which a variable numerical value of a distortion factor is found when analyzing the compressed data read out later, and the analysis is facilitated.

[0012]

In order to achieve this object, according to the present invention, there is provided a biological signal processing apparatus comprising: a data holding means for holding a biological signal of a digital signal for a predetermined time; a noise detecting means for detecting a data portion, a data compression means for compressing the bio-signal, and digital information recording medium for recording the compressed data in said data compressing means, the detection of said noise detecting means
And a data capacity monitoring control means for controlling a compression ratio of the data compression means based on the result .

According to the second aspect of the present invention,Biological signal processing device
Uses a buffer memory as the data holding means, and
Semiconductor memory or hard disk for digital information recording medium
Noise detection means, data compression means and
And a data capacity monitoring control means by one microprocessor
It consists of.

According to the third aspect of the present invention,Biological signal processing device
Indicates that the amount of compressed data is
The recording capacity of one segment that divides the recording capacity into multiple
If the data capacity monitoring and control means determines that the
In this case, the compressed data is recorded in one segment,
If the data exceeds the storage capacity of one segment,
Increase the distortion rate according to the amount of data exceeded
Compression ratio in one segment to increase the compression ratio in one segment.
Data is recorded.

[0015] According to the fourth aspect of the present invention,Biological signal processing device
Indicates that the compressed data volume is less than the recording capacity of one segment.
And the carry over of the remaining recording amount in the segment is constant.
If the recording volume is exceeded, reduce the distortion rate and compress the data.
Data capacity monitoring and control means
It is a configuration for controlling.

A fifth aspect of the present invention for achieving another object.
The biological signal processing device according to the invention described above is configured to record, on a digital information recording medium, a numerical value of a distortion rate that increases according to the amount of data that exceeds when the compressed data exceeds the recording capacity of one segment, together with the compressed data. .

[0017]

With such a configuration, the biological signal processing of the present invention can be performed.
The device compresses biological signals such as ECG data
The compression ratio based on the detection result of the noise detection means.
Control. Controlling the compression ratio involves changing the distortion ratio.
In addition, the numerical value of the distortion rate is
To memorize.

Therefore, the recording efficiency of electrocardiogram data on a relatively small and low-capacity digital information recording medium is improved, and long-time recording can be performed with high accuracy. Furthermore, a numerical value of the distortion rate that is changed when analyzing the compressed data read out later becomes clear, and the analysis is facilitated.

[0019]

Next, an embodiment of the biological signal processing apparatus of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a biological signal according to the present invention.
1 shows a configuration of an embodiment of a signal processing device . In FIG. 1, the apparatus includes an electrode unit 2 mounted on a subject, an amplifying unit 4 for amplifying an analog electrocardiogram signal Sa from the electrode unit 2, and a quantizing and sampling of the analog electrocardiogram signal from the amplifying unit 4. An A / D converter 6 that converts the digital electrocardiogram data (signal) Sd into digital electrocardiogram data (signal) Sd, a data buffer unit 8 that holds (stores) the digital electrocardiogram data Sd for a certain period of time, and a digital electrocardiogram data Sd stored in the data buffer unit 8 A noise detection unit 10 that detects mixed noise, that is, noise that becomes unnecessary data other than the desired electrocardiogram data from the subject, and outputs this noise detection data (signal) Sb.

Further, the apparatus includes a compressed ECG data (signal) S obtained by compressing the digital ECG data (signal) Sc.
f, a data capacity monitoring controller 14 for controlling the compression rate in accordance with the information amount of the noise data portion in the electrocardiogram data, and a digital information recording medium such as a semiconductor memory or a small hard disk. An information recording medium 16 for recording and removing the compressed electrocardiogram data Sf from the data compression section 12 and attaching it to another device to read out the recorded data, and a power supply for supplying a predetermined voltage V to each section. And a portion 18.

Next, the operation of this embodiment will be described. FIG. 2 is a flowchart showing a processing procedure in the operation of this configuration. In FIG. 2, an analog electrocardiogram signal Sa from the electrode section 2 is amplified by an amplification section 4 and then converted into digital electrocardiogram data Sd by an A / D converter 6.
Is converted to The digital electrocardiogram data Sd is held (stored) by the data buffer unit 8 for a certain period of time.
Is read.

In this case, it is determined whether a predetermined amount of digital electrocardiogram data Sd has been stored in the data buffer section 8 (step 12). If a predetermined amount of digital electrocardiogram data Sd has been stored in step 12, the process proceeds to the next step if YES, and returns to step 10 if no,
The storage process is performed until a predetermined storage amount is reached. Each time the data buffer unit 8 reaches a predetermined storage amount, the digital electrocardiogram data Sd is output to the noise detection unit 10 and the data compression unit 12. The noise detection unit 10 performs the digital electrocardiogram data Sd
The noise mixed in is detected (step 13). The noise detection data Sb indicating the presence / absence of the noise is sent to the data capacity monitoring control unit 14. The noise detector 10 detects inflection points of the digital electrocardiogram data Sd, measures the amplitude between the inflection points, and counts the number of inflection points whose amplitude exceeds a predetermined value for a certain data length. , The noise is determined and detected.

The data capacity monitoring controller 14 determines the presence or absence of noise from the noise detection data Sb (step 1).
4). If there is no noise data in this step 14 or if NO is smaller than the predetermined amount, the data compression unit 12 controls the digital electrocardiogram data Sc from the data buffer unit 8 under the control of the data capacity monitoring control unit 14 in advance. Compressed at the distortion rate a, and the compressed ECG data Sf subjected to the compression processing is transmitted.

In the case of YES at step 14 having noise data, the digital electrocardiogram data Sc from the data buffer unit 8 is converted by the data compression unit 12 to the reference distortion rate a by the control signal Se from the data capacity monitoring control unit 14. The compression is performed at a larger distortion rate b, and the compressed electrocardiogram data Sf is transmitted (steps 15, 16, 17). In this way, the distortion rate b of the noise data having a large information amount is made larger than the reference distortion rate a to reduce the amount of noise data to be compressed, so that the compression efficiency is improved.

After this compression processing, the data capacity monitoring control unit 14 determines the data amount in the compressed electrocardiogram data Sf compressed by the data compression unit 12. That is, the data capacity monitoring control unit 14 manages the entire recording capacity of the information recording medium 16 as a large number of segments (delimiters), and the amount of compressed data in the compressed electrocardiogram data Sc compressed by the reference distortion rate a and the distortion rate b. Is larger than the preset recording capacity of one segment of the information recording medium 16 (step 18).

In step 18, if the compressed data amount is within one segment capacity of the information recording medium 16 (NO), the compressed data is recorded in one segment of the information recording medium 16. The remaining storage capacity of the segment is added to the next segment capacity. If the compressed data amount is equal to or larger than one segment capacity of the information recording medium 16 in step 18, the data capacity monitoring controller 14 increases the reference distortion rate a and the distortion rate b according to the exceeded storage capacity ( Step 19).

Therefore, in step 19, the data capacity monitoring control unit 14 controls the data compression unit 12 to perform data compression again, and further, the data capacity monitoring control unit 14 determines The distortion rate b that can be recorded in the segment is controlled. In this case, the reference distortion rate (a) is changed, and the digital electrocardiogram data Sc from the data buffer unit 8 recorded at this reference distortion rate (a) is
The numerical value of the distortion factor is simultaneously recorded so that it can be referred to later (step 20).

When the data amount of the digital electrocardiogram data Sc falls below the segment capacity of the information recording medium 16 and the carry over of the remaining recording capacity exceeds a certain amount, for example, one segment capacity, a sufficient compression ratio is obtained. The data capacity monitoring controller 14 determines that the digital electrocardiogram data Sd is obtained. That is, it is determined that the analog electrocardiogram signal Sa with little noise is being input. Thereafter, the data capacity monitoring and control unit 14 controls the data compression unit 12 to perform data compression with a distortion rate smaller than the reference distortion rate a (steps 21, 22, 23). With this control, the recording capacity of the information recording medium 16 can be effectively used. In this step 23, the processing procedure so far ends, and thereafter, the process returns to the initial setting.

It should be noted that the individually configured noise detectors 10,
The data compression unit 12 and the data capacity monitoring control unit 14 may be configured by one microprocessor, and perform the same processing by software.

[0030]

As is apparent from the above description, the biological signal processing apparatus of the present invention varies the distortion rate in accordance with the information amount of a noise data portion in a biological signal such as electrocardiogram data.
Controls the compression ratio. Further, the variable numerical value of the distortion rate is stored together with the compressed data.

[0031] This improves the compression efficiency of the biological signal, further, a relatively semiconductor memory small form, the digital information recording medium such as a hard disk, to improve the recording efficiency when recording a biological signal, and high This has the effect that recording can be performed with high accuracy. Further, there is an effect that a variable distortion factor is found when the compressed data read out later is analyzed, and the analysis becomes easy.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a biological signal processing device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a processing procedure in the embodiment.

[Explanation of symbols]

Reference Signs List 6 A / D converter 8 Data buffer unit 10 Noise detection unit 12 Data compression unit 14 Data capacity monitoring control unit 16 Information recording medium Sa Analog electrocardiogram signal Sb Noise detection data Sc, Sd Digital electrocardiogram data Se Control signal Sf Compressed electrocardiogram data

Claims (5)

(57) [Claims] And 1. A data holding means for holding a predetermined time biological signal of a digital signal, a noise detecting means for detecting a noise data portion from the biological signal, and data compression means for compressing the bio-signal, the data compression a digital information recording medium for recording the compressed data unit, said Bruno
The data compression means based on the detection result of the noise detection means.
Data capacity monitoring control means for controlling the compression ratio of the
Biological signal processing device . 2. A buffer memory is used for data holding means, a semiconductor memory or a hard disk is used for a digital information recording medium, and a noise detecting means, a data compressing means and a data capacity monitoring control means are constituted by one microprocessor. The biological signal processing device according to claim 1, wherein: 3. The data capacity monitoring control means determines that the amount of compressed data does not exceed the recording capacity of one segment obtained by dividing the entire recording capacity of the digital information recording medium into a plurality of segments. If the compressed data exceeds the recording capacity of one segment, the distortion rate is increased in accordance with the amount of data that has been exceeded, and the compression rate of the data compression means is increased to increase the compression rate in one segment. 2. The biological signal processing device according to claim 1, wherein the compressed data is recorded in the memory . 4. When the amount of compressed data falls below the recording capacity of one segment and the carry over of the remaining recording amount in the segment exceeds a certain recording amount, the data is compressed so as to reduce the distortion rate and perform data compression. raw claim 1, wherein the capacity monitoring control means controls the data compression means
Body signal processing device . 5. The digital information recording medium according to claim 1, wherein when the compressed data exceeds the recording capacity of one segment, a numerical value of the distortion rate increased according to the amount of data exceeded is recorded together with the compressed data on the digital information recording medium. Biological signal processing according to 3
Equipment .