JPS61217135A - Living body signal input apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for inputting biological signals with high resolution.

In recent years, computer processing has been increasingly used in devices that detect and analyze brain waves, electromyograms, electrocardiograms, etc. from living bodies. Generally, an A/D converter that converts biological signals converts the voltage value of a sample point in the dynamic range of the input voltage of the A/D converter into the conversion bit number of the A/D converter, as shown in Figure 1(a). Convert to digital signal with resolution according to The number of conversion bits is related to the processing capacity of the computer, and the higher the number of conversion bits, the higher resolution processing becomes possible. However, as the "number of conversion bits" increases, the memory capacity increases proportionally, and the size of the entire device also increases.

For this reason, especially when applied to an electrocardiograph that is always carried, such as a Holter electrocardiograph, the number of conversion bits is also generally limited because the extent of the portable electrocardiogram recorder is limited. That is, when the number of conversion bits is small, the minimum value of the converted voltage exceeds the voltage value of the small amplitude portion of the biological signal, so there is a problem that the original biological signal cannot be faithfully input.

In view of the above, the present invention uses the number of conversion bits of the A/D humbator to sufficiently detect information on characteristic parts that are conventionally effective information but difficult to detect due to minute amplitudes, and detect biological signals with high resolution. The purpose of the present invention is to provide a biosignal human-powered device that inputs biosignals.

The present invention is an apparatus for A/D converting an input biological signal, which generates a difference value signal between a human input biological signal and a biological signal input at a predetermined interval, and converts this difference value signal into an A/D converter. The gist of the present invention is to output a differential digital signal by inputting it to a D converter.

The difference value signal in the present invention indicates the voltage corresponding to the change in the biological signal as shown in FIG. 1(b), and by integrating this, the original signal can be easily derived. When comparing the maximum amplitude of the biological signal with the maximum amplitude of the difference value signal, it is obvious that the maximum amplitude of the difference value signal is smaller than the maximum amplitude of the biological signal. Therefore, the dynamic range of the A/D converter that converts this difference value signal into a digital signal can be made smaller than when the original biological signal is directly input. For example, if an 8-bit A/D converter is used and the dynamic range of the biological signal is 10 (mV), the resolution of the A/D converter is 10 (mV) ÷ (28-1) = 0.039. (
mV), whereas if a difference value signal is input,
For example, the dynamic range can be set to 1 (mV), and the resolution is 1 (mV) ÷ (2”-1)
=0.0039(a+V).

Next, the present invention will be described in detail with reference to the drawings of an embodiment of the present invention.

FIG. 2 is a block diagram showing an embodiment of the present invention. Third
The figures are signal waveform diagrams at each part in Figure 2. Figure 2 (a) is Figure 3 (a), Figure 2 (b) is Figure 3 (b), Figure 2 (
c) respectively correspond to FIG. 3(c).

The electrocardiogram signal (,) is input to the differential amplifier (21) (a)
is input. The output (c) of the differential amplifier (21) is an A/D humbverter (with a small dynamic range).
22). The output of the A/D converter (22) is connected to the output end (d). Also A/D Humbata (
The output of the integrator (22) is input to the integrator (23), and the integrator (2
The output of 3) is connected to the output terminal (e) and the storage circuit (24). Further, the output of the memory circuit (24) is connected to a D/A converter (25), and the output thereof is input to the input section (b) of the differential amplifier (21). Here, the D/A converter (
25) requires the resolution of the A/D converter (22) and the number of bits sufficient to compensate for the dynamic range of the input section y(a).

The operation of the apparatus configured as above will be explained next.

In the memory circuit (24), the input section (b) of the differential amplifier (21) is E, (V) until the electrocardiogram signal first arrives.
The situation is as follows. Input section (a) of differential amplifier (21)
), the voltage difference between the input part (b) and the output part (c) of the differential amplifier (21) is amplified.
is output to. This signal is sent to the A/D converter (22)
A digital signal corresponding to the amplitude value of the difference signal is output to the output section (d).

On the other hand, the digital signal output from the A/D converter (22) is sequentially integrated by the integrator (23), and the integrated digital data is output to the output section (e) and stored in the storage circuit (24). be remembered. This memory circuit (24
) The data output from the D//A converter (2
5) into an analog signal, and this analog signal is sent to the input section (b) of the differential amplifier (21) as a processed signal.
) is entered. The analog signal of this input section (b) is
The data stored in the memory circuit (24) is D/A converted and output, and for the input signal Fig. 3 (,),
Signal delayed by time T indicating a predetermined period FIG. 3(b)
Here, the output 1(d) in FIG. 2 outputs a digital signal of an electrocardiogram difference value signal, and the output terminal (e) outputs a digital signal of an electrocardiogram signal. These signals are inputted as appropriate by an analysis device or the like.

Note that the data stored in advance in the recording circuit sets the output voltage E, (V) of the D/A converter, but it can be set arbitrarily, and preferably, it is set to the baseline voltage. Furthermore, the storage time of the recording circuit is equal to the delay time T between the input section (,) and the input section (b) in FIG. It is set at the sampling cycle time of the D/A converter, preferably at one sampling cycle, but it is selected as appropriate so that the generated difference value signal shows the required resolution. It is. Further, the means for generating the delay time T may generate the difference value signal by using analog delay means, digital delay means, or the like.

Therefore, according to the present invention, by inputting the difference signal between the original biosignal and the delayed signal to the A/D conversion means and outputting a digital signal, the original electrocardiogram signal is directly input to the A/D conversion device having the same number of bits. This has tremendous effects in use, such as making it possible to detect biological information that would otherwise be difficult to detect because the amplitude is minute compared to when the sensor is used.

[Brief explanation of drawings]

FIG. 1(,) is a waveform diagram showing the sample voltage with respect to the sampling time of the A/D converter in an example of the electrocardiogram signal waveform. FIG. 1(b) is a waveform diagram showing an example of the difference value signal of the electrocardiogram signal. FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a waveform diagram of each part of FIG.゛21... Differential amplifier (difference value signal generation means), 22.
...A/D converter (A/D conversion means), 23...
Integrator (integration means), 24... Memory circuit (memory means), 25... D/A humbator (D/A conversion means). Patent applicant Advance Development Institute Co., Ltd. Figure 1 Hatauta time Figure 3 CC)

Claims (2)

[Claims] (1) A protobiotic signal is input to one input terminal of the two input terminals, and a processed signal of the protobiotic signal from a certain period of time ago is input to the other input terminal, and between these two input terminals a difference value signal generating means for generating a difference value signal; and an A/D converting the output of the difference value signal generating means into a digital signal.
a conversion means, an output terminal of the A/D conversion means and the A/D conversion means;
an integrating means for integrating the output of the D converting means; a storage means for temporarily storing the output integrated by the integrating means; and a D/A for converting the output of the storing means into an analog signal.
A biological signal input device, wherein the processed signal is input to a converting means, and the output of the D/A converting means is the processed signal. (2) The first protobiotic signal is one of the difference value signal generation means.
The storage means stores any pre-stored signal from the time it is input to the D/D input terminal until it is input to the storage means via the A/D conversion means and the integration means.
2. The biological signal input device according to claim 1, wherein the biological signal input device outputs the signal to another input terminal of the difference value signal generation means via an A conversion means.