JPS5819226A - Apparatus for sampling body signal - 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] (Technical field to which the invention pertains) The present invention provides bioreliability such as electrocardiogram, respiratory line, blood pressure, etc. When decoupling a signal, a biological signal is used, which is an analog signal.

This invention relates to a sampling device for biological signals when converting signals into digital signals.

(Prior art) Conventionally, the method of converting an analog biological signal into a digital signal is to sample the analog biological signal at the basic sampling frequency or hold the f or peak value (maximum value or maximum/J1 value). There was a method of sampling using a circuit.

In the former method, as shown in Figure 1, P, Q, R
, 8. It is economical to minimize the memory capacity for storing sampled values for biological signals such as electrocardiogram signals, which have T6 waves and whose combined amplitude information is important for diagnosis. A low sampling frequency was used, but in this case, the peak value, which is the maximum or minimum value, is the positive iIK
There was a drawback that sampling was not performed (Objective of the Invention) In order to eliminate the above drawback, the present invention sets an arbitrary number of sampling points within the basic sampling period of analog biological signals, and also sets the sampling value of this sampling point. Compared to.

By detecting the rate of change, when the rate of change is increasing, the maximum value among the KK sampling values is set as the sampling value of the basic sampling point, and when it is decreasing, the minimum value is set as the sampling value of the basic sampling point. It is an object of the present invention to provide a biological signal sampling device that takes sampling values at basic sampling points and converts these sampling values into digital signals (OX principle of the present invention). A lot.

The horizontal axis is the time axis, and the vertical axis is a diagram showing the amplitude value of the analog biological signal for each time.
The sampling value of the biosignal with respect to the basic sampling time which is the period Δt shown by -・- is Y(t i+1
), Y(t 1-4-2)...Y(t i+
j )−・・・・・・・. Furthermore, the biological signal is sampled in the basic sampling period with a sampling frequency that is twice the basic sampling frequency (K: integer), and the 701 printer value is calculated as Y (ti + j + ¥) - Y (ti + j +
),... That is, the minimum sampling interval is the basic sampling period Δt(-ti+1-
1i) divided by K is Δt/.

The sample value Y(ti+j) sampled in the 1Kth arbitrary basic sampling period is compared with the auxiliary sample 2 obtained when each basic sampling interval is sampled at a frequency twice the basic sampling frequency.

@, in the basic sampling interval t i+1 to ti+2, the basic sampling values Y(t i+1 ), y(
ti+2) and the result is Y(ti+2)≧Y←
i+1) Apparently, the 4° amplitude value of the biological signal with respect to time has an increasing tendency KTo y(tt+1)(t-1
i+1) t Y(t i+i+￥)-----Y(t
i+24) To? Compare the sampling value that becomes the maximum value at flJ1ti+i.

Let the sampling value be 0, ie.

−−−−−−y(t +−1−2−¥month・・・・−song(
It satisfies the relational expressions such as 1).

By sequentially repeating this operation, numbering can be performed as the maximum sampling value C″t Y (t i 10g) existing in the interval between the basic numbering times ti-4-3 and t1-)-4. .

Next, the basic sampling time tL4-4 and ti-1-5
For the interval Y(t
l+3)<I Let us compare the movement and the basic sampling value Y(ti+4) at the basic sampling time ti+4.

y(t 113))Y(t ゑ+4), so there is *1 point between the basic sampling time tt-4-3 and ti+4, and the basic sampling interval ti+4
It can be determined that the -th +5 Fi is decreasing, and therefore, in the basic sampling interval ti+4 to ti-1-5, the basic sampling value Y (ti is the sampling value at time ti+4. That is,.

. . . Y(ti-1-4-γ)).

In the same way, the minimum value points are sampled in the ti-1-7 and +8N- intervals, and this is taken as the sampling value of Y(ti+7).Furthermore, if one interval is sampled from ■+8 to tl+9-, Y( t i+8 )−Y(t i
Since +7)≧0, it can be seen that there is an inflection point within the interval between ti-H and ti50, and it is determined that the biological signal is on an upward trend. Therefore, the maximum value among the sampling values between ti-H and ti10g-Tsum is taken as the sampling value of ti+8.

If you use the sampling method described above.

0 (Example of an apparatus using the principle of the present invention) that makes it possible to sample values close to the maximum value (or local maximum value) and minimum value (or local minimum value) without increasing the memory capacity. ) FIG. 3 shows an embodiment of a biological signal sampling device using JiKjl of the present invention. Below, the sampling device of the present invention will be described with reference to FIG. 3.

(Description of configuration) A terminal 1 into which a biological input signal is input is connected to an input end of an amplifier 2, and an output end of the amplifier 2 is connected to an input end of an analog/digital converter 30 that converts an input analog signal into a digital signal. In addition, the analog/digital converter (hereinafter abbreviated as VD converter) 3 is supplied with a first clock pulse having a frequency equal to the basic sampling frequency in order to control the analog/digital conversion operation. Generating circuit 4 is connected o
A second basic sampling clock pulse generation circuit 5 for dividing the clock pulse output from the clock pulse generation circuit 4 of the ME 1 and outputting a basic clock pulse is connected to the first clock pulse generation circuit 4. There is. The output terminal of the analog/digital converter 3 has local maximum value and local minimum value detection for detecting the local maximum value and local minimum value of the sampling value within the basic sampling period according to the output from the first clock pulse generation circuit 4. A local maximum latch circuit 7 is connected to the output terminal of the 0A/D converter 3 to which the circuit 6 is connected. Minimum value latch circuits 7 and 8 are connected in parallel, and these latch circuits 7 and 8 are extremely thick.

It is connected to the minimum value detection circuit 6 so as to be able to send and receive signals.

An output pulse K18 from the basic sampling clock pulse generation circuit 5 is applied to the output terminal of the A/D converter 3.
A first basic sampling value latch circuit 9 is connected to latch the output value from the D converter 3. A second basic sampling value latching circuit 1O is connected to latch the sampling value of the next time after the sampling value from the A/D converter 3 that has been turned on. A comparison circuit 11 is connected to each of the latch circuits 9 and 10, which compares the nine sampled values latched therein.

An inflection point detection circuit 12 connected to this comparison circuit 11 and an inflection point detection circuit 12 for detecting an inflection point of an input biological signal according to an output signal from the comparison circuit 11 A data selector circuit 13 latches the output signals from the maximum value and minimum value latch circuits 7 and 8 according to the output signal from the comparator circuit 11 and the output signal from the comparison circuit 11, and then selects and outputs a digital value as a basic sampling value. It is provided.

(Description of the operation of this embodiment) The biological signal inputted from the actuator 1 is amplified by the amplifier 2, and the A/D converter 3 converts it into a signal at the basic sampling frequency from the first clock pulse generation circuit 4. The analog signal is converted into a digital signal by a clock pulse having a frequency of .

Next, the first clock pulse is generated! A second basic sampling clock pulse generator 5 that divides the four clock pulses from a4 and outputs nine reference sampling clock pulses.
The output from the A/D converter 3 is provisionally applied to the maximum value latch circuit 7 according to the output from the A/D converter 3. and are latched by the minimum value latch circuit 8, respectively.

In addition, the local maximum/minimum value detection circuit 6 compares the A/D-converted nine latest output values with the data latched in the local maximum latch circuit 7, and the latest data is the data latched by the local maximum latch circuit 7. Only when the current value is large, the maximum value is updated by latching the latest data in the maximum value latch circuit 7.

At the same time, the latest data is compared with the data latched in the minimum value latch circuit 8, and only when the latest data is smaller than the data latched in the minimum value latch circuit 8, the latest data is latched in the minimum value latch circuit 8. To do this, update the local minimum value.

The data from the A/D converter 3 is latched in the first basic sampling value retrieval circuit 9 according to the output pulse from the second basic sampling pulse generator 5, and
By the same output.

Latch circuit 9 to second basic sampling value latch circuit 1
1m data is transferred.

In synchronization with the output pulse from the second basic sampling clock pulse generator 5, the data of the latch circuit 9 and the data of the latch circuit 10 are compared in the comparator circuit 11, and whether there is an increasing or decreasing trend with respect to each data. judge,
A signal indicating the result is output to the data selector circuit 13 and the inflection point detection circuit 12.

An inflection point detection circuit 1 receiving an output signal from a comparison circuit 11
2ti, detects whether the change is from an increase to a decrease or from a decrease to an increase, and outputs a detection signal to the data selector circuit 13.

Then, the data selector circuit 13 operates the maximum value latch circuit 7 . Select and latch either the data of the data or the minimum value latch circuit 8, and output this latched value as the basic sampling value as the digital value of the A/D conversion edge. without being limited to 9
For example, in the above embodiment, the minimum sampling was set to Δt/ with a constant within the basic sampling interval, but J and K may be made variable depending on the type of biosignal or the frequency component of the biosignal. Good too.

(Effects of the Present Invention) As explained above, according to the device of the present invention, when converting an analog biological signal into a digital signal, the analog signal can be converted into a digital signal without increasing the memory capacity for storing sampled values. The value 1+ allows accurate sampling of the peak value, which is the minimum value.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an electrocardiogram waveform as an example of a biosignal, Fig. 2 is a conceptual diagram for explaining the biosignal sampling principle and method of the present invention, and the third shoe is an implementation of the biosignal sampling device according to the present invention. FIG. 2 is an example circuit configuration diagram. 1.../+;Kyushintai, 2...Amplifier,
3...-ADC circuit. 4... K US basic sampling clock circuit, 5.
- Basic sampling clock frequency divider circuit, 6...
...Local maximum/minimum value detection circuit, 7...Local maximum value latch circuit, 8...-゛・9. Minimum value latch circuit, 9...
-...tj-based basic sampling latch circuit 10
...tj-1a main sampling value latch circuit,
11... Size comparison circuit, 12... Inflection point detection circuit, 13... Data selector circuit, 1
4...Basic sampling ADC value Representative patent attorney Kensuke Chika (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] A circuit that converts a biological signal, which is an Anapda signal, into a digital signal for each scheduled time and each unit time subdivided into the scheduled time, and a local maximum value holding circuit that holds the maximum value of the converted digital signal. The minimum value holding circuit that holds the minimum value of the digital signal and the converted digital signal at scheduled times are compared with the signals held by the wrinkle maximum value holding circuit and the minimum value holding circuit to detect local maximums and minimum values. A maximum/minimum detection circuit, a circuit that holds a digital signal converted at each scheduled time and a certain period of time before the scheduled time, and a circuit that compares the signal held at each scheduled time with a signal at a certain period of time before the scheduled time. A biological signal characterized by comprising a magnitude comparison circuit and a circuit that selects and outputs the signal held in the maximum value holding circuit and the minimum value holding circuit based on the signal compared by the magnitude comparison circuit. Sampling equipment.