JPH0456620B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small portable heart rate monitor.

This type of heart rate monitors currently in practical use can be roughly divided into the following two types depending on the method of calculating heart rate. One of them is
Counts the number of pulses sent from the oscillator during the first heartbeat, calculates the first heartbeat cycle from this number of pulses during the next heartbeat, and calculates and displays the heart rate per minute from this cycle. That's how it is. The other method is to integrate a reference voltage during a certain number of heartbeats, such as 10 heartbeats, and after the integration is complete, calculate and display the heart rate per minute from the voltage proportional to this time. .

It goes without saying that heart rate monitors are originally designed to measure the heart rate per minute over a short period of time, but it is desired that heart rate monitors be able to easily detect absent or irregular heartbeats. However, conventional heart rate monitors calculate the heart rate per minute by counting the number of oscillator pulses every other heartbeat, as described above, or by integrating the reference voltage for 10 heartbeats. It has become difficult to meet recent demands for detecting even absent beats and arrhythmia.

This invention was made in view of the above points, and its purpose is to provide a portable heart rate monitor with a simple configuration that can measure heart rate and reliably detect absent beats, arrhythmia, etc. during the measurement. It's about doing.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the accompanying drawings.

Referring to the block diagram shown in FIG.
This heart rate monitor includes, for example, an integrating circuit 1, a display circuit 2, and a control circuit 3. Above integration circuit 1
is for forming an analog signal corresponding to absent beats or arrhythmia and an analog signal corresponding to the heart rate per minute. The display circuit 2 is for converting these analog signals into sequential signals and displaying them on a numeric display or the like. The control circuit 3 is for switching the integration operation of the integration circuit 1 on and off in accordance with the timing of a heartbeat detection signal (hereinafter referred to as a "heartbeat signal"), which is a signal to be measured.

Next, each part will be explained in order. The integration circuit 1 includes, for example, a reference voltage generator 4 and three integrators 5, 6, and 7 that integrate the reference voltage from the reference voltage generator 4. There is. Of these, integrator 5
and 6 are for detecting missing beats or arrhythmia for each beat, and integrator 7 is for calculating the heart rate corresponding to one minute. Analog switches 8, 9, and 10 are connected to the input sides of each of these integrators 5 to 7, respectively.
to 7 are adapted to receive the reference voltage from the reference voltage generator 4 via these analog switches 8 to 10. Analog switches 11, 12, and 13 are similarly connected to the output sides of the integrators 5 to 7, respectively.
Of these, the output side of the analog switch 13 is connected to the input side of the display circuit 2, but the output sides of the other two analog switches 11 and 12 are connected by a common wiring, and this common wiring is further connected to the input side of the display circuit 2. It is connected to the input side of the display circuit 2 via an analog switch 14. Note that each of the integrators 5 to 7 is provided with an analog switch 1 for reset.
5, 16, and 17 are connected in parallel. In this embodiment, the input and output sides of the integrators 5 and 6 for detecting absent beats and arrhythmia are alternately switched on and off according to each heartbeat signal by each analog switch. The input/output side of the integrator 7 that calculates the heart rate corresponding to a minute is as follows:
When the number of heartbeat signals reaches a certain number n, it is turned on and off. In this embodiment, the constant number n is set to 10, so the analog switch 10 is turned on and the analog switch 13 is turned on until 10 heartbeat signals are input.
is off, and when the 10th heartbeat signal is received, the on/off state is reversed. The analog switch 14 is a gate for sending the outputs of the integrators 5 and 6 to the display circuit 2, and is turned on when the analog switch 13 provided on the output side of the integrator 7 is turned off. When the analog switch 13 is turned on and the output of the integrator 7 is sent to the display circuit 2, it is turned off. Each of the above integrators 5 to 7
is a general integrator composed of an operational amplifier, a resistor, a capacitor, etc., but in this embodiment, integrators 5 and 6 integrate the reference voltage for each heartbeat signal as described above. On the other hand, the integrator 7 continues its integration operation until the 10th heartbeat signal is input. In other words, the integration time is increased by 10 times. For this reason,
The integration time constants of integrators 5 and 6 are set to the same size, but the integration time constant of integrator 7 is set to be 10 times larger than those integration time constants. As a result, the integrated voltage of the integrator 7 will not become excessive, and if the same reference voltage is integrated by three integrators, the level of each integrated voltage will be in phase with each other if the timing of the heartbeat signal is normal. are considered to be equal. In this example,
As mentioned above, n=10 is set, but it is natural that this value can be determined as appropriate, taking into consideration the measurement time and measurement accuracy of heartbeats.

The display circuit 2 includes, for example, a reference voltage generator 20
It is composed of a comparator 21, an A/D converter 22, a display 23, and the like. Each integrated voltage output from the three integrators 5 to 7 of the integrating circuit 2 is applied to a reference voltage generator 2 in this comparator 21.
A level comparison is made with a reference voltage starting from 0, and the difference voltage is sent to the A/D converter 22. After this voltage difference is converted into a digital value by the A/D converter 22, it is converted into a digital value by a display device 2 having, for example, a decoder and a numerical display unit (not shown).
3, and the measured heart rate is displayed. In this case, the integrated voltage from each integrator 5 to 7 input to the comparator 21 increases as the heart rate decreases because the integration time increases, and the voltage level is not necessarily constant when the measurement target changes. This is no longer the case. Therefore, the differential voltage output from the comparator 21 also changes, but if the polarity of this differential voltage changes to positive or negative each time a measurement is made, the input circuit of the A/D converter 22 connected at the subsequent stage becomes complicated. Therefore, it is desirable that the reference voltage is set higher than the input integrated voltage corresponding to the minimum measurable heart rate.

The control circuit 3 includes, for example, a sensor 30, a waveform shaper 31, two controllers 32 and 33, and the like. The sensor 30 detects the heartbeat and converts it into a pulsed electrical signal. The output side of this sensor 30 is connected to the input side of the waveform shaper 31, and the converted electrical signal is subjected to noise components etc. removed in this waveform shaper 31, and also has a relatively narrow negative polarity. The signal is shaped into a square wave signal. This shaped signal is sent to the two controllers 32 and 33 as a heartbeat signal.
sent to.

The controller 32 is for switching the integration operation of the two integrators 5 and 6 on and off in accordance with the timing of the heartbeat signal.
It includes a stable multivibrator 34 and a monostable multivibrator 35 connected to the two output terminals Q of the bistable multivibrator 34. Furthermore, one of the two output terminals Q is connected to the analog switch 8 of the integrating circuit 1.
and 12 gate signal input sides, respectively,
The other output end is similarly connected to the gate signal input sides of analog switches 11 and 9, respectively. When the heartbeat signal is input from the waveform shaper 31, the bistable multivibrator 34 outputs two rectangular wave signals whose voltage levels are inverted from each other from the output terminals Q and Q, that is, the Q signal and the signal. It is designed to be sent out.
As a result, the analog switches 8 and 12, and 11 and 9 are controlled to be turned on and off alternately by the Q signal and the signal.

The monostable multivibrator 35 is for generating a pulse for resetting the integrated voltage up to that point when each of the integrators 5 and 6 starts an integration operation.
For example, it consists of two monostable multivibrators whose respective inputs are connected to the outputs Q and . One output side is connected to the gate signal input side of an analog switch 15 provided in parallel with the integrator 5, and the other output side is connected to the gate signal input side of an analog switch 16 provided in parallel with the integrator 6. Connected to the signal input side. In this embodiment, when the Q signal and the signal are applied from the bistable multivibrator 34, the two output sides of the monostable multivibrator 35 are compared, for example, at the falling edge of the applied Q signal or signal. Pulsed voltages of positive polarity with narrow widths are made to appear alternately, and these pulsed voltages are used for resetting as described above.

The controller 33 causes the integrator 7 to perform an integration operation while the first to 10th heartbeat signals are being input, and from the 11th heartbeat signal onwards, the integral voltage up to that point is This is to hold and send it to the display circuit 2.
The heart rate corresponding to one minute is calculated in the display circuit 2 based on this supplied voltage. In order to perform such a function, the controller 33 includes, for example, two analog switches 36 and 37, a counter 38, two bistable multivibrators 39 and 40, a monostable multivibrator 41, and a NOR circuit 42. It is composed of

The analog switch 36 is a gate for the heartbeat signal provided at the entrance of the controller 33, and is connected between the waveform shaper 31 and the counter 38, and is connected to the heartbeat signal sent from the waveform shaper 31. is added to the counter 38 via this analog switch 36. The analog switch 37 is a bypass gate connected in parallel with the counter 38, through which the first heartbeat signal among the heartbeat signals applied to the counter 38 is sent to the subsequent stage. However, the second and subsequent heartbeat signals are blocked.

The counter 38 has its input side connected to the output side of the analog switch 36, and counts the heartbeat signals inputted via the analog switch 36. The heartbeat signals up to the point are counted. Therefore, in this embodiment, for example, a binary decimal counter is used, and when the counting of the 10th heartbeat signal is completed, a reset pulse is emitted at the timing of the next 11th heartbeat signal. There is.

A bistable multivibrator 39 is connected to the output side of the counter 38. The two output terminals Q and of this bistable multivibrator 39 are connected to the gate signal input sides of analog switches 10 and 13 provided on the input and output sides of the integrator 7, respectively, and the output terminal Q is also connected to the input side of the monostable multivibrator 41. This bistable multivibrator 39 turns on the input-side analog switch 10 of the integrator 7 by its Q output while the counter 38 is counting the first to tenth heartbeat signals, and turns on the output-side analog switch 10 by its Q output. 13 is turned off by its output. When the counter 38 completes counting and issues a reset pulse, the voltage levels of the Q output and the output are inverted, and thereby the two analog switches 10 and 13
The on and off states are now interchangeable.

The bistable multivibrator 40 is for controlling the input of the heartbeat signal by turning on and off the analog switch 36 provided on the input side of the counter 38, and its output terminal Q is connected to the analog switch 36. connected to the gate signal input side of the The input side of this bistable multivibrator 40 is connected to a power source 44 via, for example, a push-type start switch 43, and when the start switch 43 is pressed, a portion of the power source voltage is applied. Normally, an L level voltage appears at the output terminal Q of the bistable multivibrator 40, and the analog switch 36
is set to be in an off state, but when voltage is applied for a short time by operating the start switch 34, the voltage at the output terminal Q is inverted to H level and the analog switch 36 is turned on. .

The above-mentioned monostable multivibrator 41 is the above-mentioned 2
When the rectangular wave voltage appearing at the output terminal of the stable multivibrator 39, that is, the output, is input, for example, a relatively narrow positive pulse voltage is generated at the output terminal Q at the falling point. ing. The output terminal Q of this monostable multivibrator 41 is connected to the analog switch 1.
The integrator 7 is connected to the gate signal input side of the integrator 7, and when a pulse voltage is generated at the output terminal Q, the integrator 7 is reset.

A NOR circuit 42 is connected to the output side of the bistable multivibrator 39. This NOR circuit 42 controls the bistable multivibrator 40 when the counter 38 finishes counting heartbeat signals.
This is for reversing the operation of the analog switch 36 and turning off the analog switch 36. One input side of this NOR circuit 42 is connected to the bistable multivibrator 39.
is connected to the output terminal Q of the output terminal Q, and an L-level voltage is applied to the other input side. Its output side is commonly connected to the input side of the bistable multivibrator 40 together with the wiring of the start switch 43. In this embodiment, the counter 3
Q of bistable multivibrator 39 while 8 is counting
The output is set to H level, so the output side voltage of this NOR circuit 42 is set to L level. In other words, when the start switch 43 is momentarily pressed to cause the heart rate monitor to start operating, the state of zero voltage is not changed when the start switch 43 is released. However, when the counter 38 finishes counting, a reset pulse is sent out, which causes the Q output of the bistable multivibrator 39 to go to L level. Therefore, the output of the NOR circuit 42 changes from L level to H level, and the Q output of bistable multivibrator 40 is inverted from H level to L level. The analog switch 36 is turned off,
The heartbeat signal sent from the waveform shaper 31 is blocked here.

In this case, the monostable multivibrator 41
As mentioned above, the counter 38 responds to the fall of the output applied from the bistable multivibrator 39 in the previous stage.
completes counting and sends out a reset pulse, and even if the output of the bistable multivibrator 39 inverts from L level to H level, it does not respond to the rise. Therefore, the Q output of the monostable multivibrator 41 remains at the L level and does not change, and the analog switch 17 also remains off, so the integrated voltage of the integrator 7 is sent to the display circuit 2 without being cleared. .

Next, the functions of the controller 32 and integrators 5 and 6 of this heart rate monitor will be explained with reference to FIG. In FIG. 1, the same reference numerals are given to the parts where the signal waveforms shown in FIG. 2 appear. First, a power switch (not shown) is turned on, and then the start switch 43 is momentarily pressed to activate the heart rate monitor.

When the sensor 30 detects the heartbeat and converts it into a pulsed electrical signal, the signal is input to the waveform shaper 31, and its output side receives a pulsed signal of negative polarity as shown in A. A signal appears, namely the heartbeat signal mentioned above. This heartbeat signal is 2
The input is input to the stable multivibrator 34, and its output terminals Q and C are respectively shown in FIGS.
Two outputs, Q output and output, which are level voltages, appear alternately in synchronization with the input timing of the heartbeat signal.

When these Q output and output are input to the monostable multivibrator 35, the output side is synchronized with the falling timing of this input signal.
For example, pulsed voltages as shown in D and E appear alternately.

In this embodiment, the Q output shown in B is used, for example, to turn on and off the analog switch 8 on the input side of the integrator 5 and the analog switch 12 on the output side of the integrator 6, and the output shown in C is For example, the output side analog switch 11 of the integrator 5 and the integrator 6
It is used to turn off and turn on the analog switch 9 on the input side. Furthermore, the pulse voltage shown in D is used as a reset pulse to clear the residual voltage when the integrator 6 starts integration, and the pulse voltage shown in E is used as a reset pulse to clear the residual voltage when the integrator 6 starts integration. Used for reset pulse.

In this way, the input and output sides of the integrators 5 and 6 are controlled on and off by the two rectangular wave signals of the Q output and the output, and are alternately cleared by the two reset pulses. Its operation is shown, for example, in the bottom. In this case, the hatched portion with respect to the horizontal axis represents the integrating operation of the integrator 5, and the portion parallel to the horizontal axis represents the holding operation of the integrated voltage. Similarly, FIG. 6 also represents the integrating operation and the integral voltage holding operation of the integrator 6, respectively. The integrated voltages of these integrators 5 and 6 are synthesized in chronological order in synchronization with the input timing of the heartbeat signal, for example as shown in H, and sent to the display circuit 2 via the gate analog switch 14. . Looking at the waveform shown in H above, arrhythmia or missing beats can be easily detected from the level of the integrated voltage level between each heartbeat signal. Furthermore, it is clear that if the heartbeat is normal, the integrated voltage level will be flat.

Next, the functions of the controller 33 and the integrator 7 will be explained with reference to FIG. 3, and the functions of this heart rate monitor as a whole will also be described. In FIG. 1, the same reference numerals as in FIG. 2 are given to the parts where the signal waveforms shown in FIG. 3 appear.

First, turn on the power switch (not shown) to supply power to each part from the power source 44, and then press the start switch 43 momentarily to activate the heart rate monitor, as described in the explanation with reference to FIG. 2. It is. In this case, the start switch 43
Assuming that the time when the button is pressed is t1, at this time t1, a part of the power supply voltage as shown in FIG. 3 is applied to the bistable multivibrator 40 via the start switch 43, for example. The Q output of the bistable multivibrator 40 is set to the L level when the power switch is on, but when the voltage is applied as described above by operating the start switch 43, the voltage shown in FIG. The signal is inverted to H level. As a result, the controller 33
The analog switch 36 provided at the entrance is turned on.

The heartbeat signal shown in FIG. is also added to the analog switch 37. in this case,
The second-stage bistable multivibrator 39 is
Like the stable multivibrator 40, its Q
Since the output is at the L level and the output is at the H level, the analog switch 37 is in the on state. Therefore, the first heartbeat signal passes through here to the bistable multivibrator 39.
added to. When this first heartbeat signal is applied, the output level relationship of the bistable multivibrator 39 is reversed as shown in W and F of the figure, and the Q output becomes H level and the output becomes L level. . Therefore, the analog switch 37 is turned off, and the second and subsequent heartbeat signals cannot pass through it.

When the first heartbeat signal is applied to the bistable multivibrator 39, the H level Q output shown in W and the L level output shown in F appear at the output end of the bistable multivibrator 39. The analog switch 10 on the input side of the device 7 is turned on, and the analog switch 13 on the output side thereof is turned off. On the other hand, at the time when the output falls, a reset pulse, for example as shown in FIG. The integrator 7 is thereby cleared and integrates the reference voltage applied from the reference voltage generator 4 as shown in FIG.

Next, when the counter 38 finishes counting the 10th heartbeat signal, a counting reset pulse of negative polarity is emitted at time t2, for example, as shown in FIG. be done. This bistable multivibrator 39
As shown in W and F of the figure, the operation is reversed again at time t2, and the Q output becomes L level and the output becomes H level. This L level Q
When the output is applied to the NOR circuit 42, the output side of the NOR circuit 42 has an H level as shown in FIG.
level voltage appears. As a result, the operation of the bistable multivibrator 40 is reversed as shown in FIG. 4, and its Q output changes to L level. The analog switch 36 receives this L-level Q output and turns off, thereby blocking the input of the 11th and subsequent heartbeat signals.

In this case, the bistable multivibrator 39
The Q output brought to the L level is applied to the analog switches 10 and 14, and both analog switches are turned off. On the other hand, the output set to H level is applied to the analog switch 13, and this analog switch 13 is turned on. At this time, the above output is also input to the monostable multivibrator 41;
As mentioned above, it operates at the falling edge of the input signal. Therefore, at time t2, the Q output remains at the L level and does not change, as shown in y in the figure, and the integrator 7
The voltage integrated from t1 to t2 is held after time t2 and is never cleared. The integral voltage of the integrators 5 and 6 for each beat and the integral voltage of the integrator 7 during the period from time t1 to t2 are switched at time t2, as shown in FIG. That is, before t2, the integrated voltage for each beat is sent to the display circuit 2, and after t2, the integrated voltage accumulated up to that point is sent.

In addition, if it is desired to repeat this measurement, it is sufficient to press the start switch 43 each time.

As described above in detail, the heart rate monitor according to the present invention operates in synchronization with the electrical signal when the sensor 30 detects the heartbeat of the scapula and converts it into an electrical signal, and operates every heartbeat. The first one, which integrates the reference voltage and outputs it alternately, has the same integration time constant.
and a second two integrators 5, 6, and a third integrator that has an integration time constant that is, for example, 10 times larger than these integrators 5, 6, and continuously integrates the reference voltage over 10 heartbeats. and an integrator 7. Furthermore, two controllers 3, a first and a second, are used to switch and operate these three integrators at predetermined timings.
It has 2.33. The first controller 32
converts the electric signal from the sensor into a control pulse for each heartbeat, and uses this control pulse to alternately turn on and off the input and output sides of the first and second integrators 5 and 6. ing. The second controller 33 counts electrical signals sent from the sensor 30 from the first heartbeat to the 10th heartbeat,
A control pulse is formed that makes the counting period the previous half cycle and the subsequent period the second half cycle, and this control pulse causes the third integrator 7 to
input and output sides and the first and second integrators 5,
The output side of 6 is controlled to be turned on or off. As a result, in the previous half cycle, each integrated voltage of the first integrator 5 and the second integrator 6 is sent out alternately every beat and converted into a digital value, and the state of the arrhythmia or missing beat is detected. It is displayed on the display 23. In addition, in the latter half cycle, the integrated voltage from the third integrator 7 is switched and sent out instead of the first and second integrators 5 and 6, and converted to a digital value, and the heart rate corresponding to one minute is calculated. is displayed on the display 23.

Therefore, according to the heart rate monitor according to the present invention,
Of course, it is possible to measure the heart rate corresponding to one minute, but it is also possible to easily and reliably detect arrhythmia or absent beats in individual heartbeats.

[Brief explanation of the drawing]

The attached drawings all relate to embodiments of the heart rate monitor according to the present invention, and FIG. 1 is a block diagram showing its overall configuration, and FIG. 2 shows signals of various parts related to the operations of the first integrator and the second integrator, respectively. FIG. 3 is a timing chart of various signals related to the operation of the third integrator. In the figure, 1 is an integration circuit, 2 is a display circuit, 3 is a control circuit, 4 is a reference voltage generator, 5, 6, 7 are integrators, 8, 9, 10, 11, 12, 13, 14, 3
6 and 37 are analog switches, 22 is an A/D converter, 30 is a sensor, 32 is a first controller, 33
is a second controller; 34, 39, and 40 are bistable multivibrators; 35 is a monostable multivibrator; and 38 is a counter.

Claims (1)

[Claims] 1. A conversion circuit that converts heartbeat into a pulsed electrical signal via a sensor, an integrating circuit that integrates a reference voltage in synchronization with the electrical signal output from the converting circuit, and and a control circuit that forms signals for controlling operation, and converts an integrated voltage from the integrating circuit into a digital value via an A/D converter, wherein each of the integrating circuits has equal integrals. first and second integrators having time constants, a third integrator having an integration time constant n times larger than the integration time constant, and inputs and outputs of the first to third integrators. a switch provided on each side, the control circuit including a first bistable multivibrator driven by the pulsed electrical signal, and an input switch of the first and second integrators; a first controller that alternately controls on and off a switch provided on the output side to cause each integrator to perform an integral operation of the reference voltage alternately; a base counter, and respective switches provided on the input and output sides of the third integrator in response to the first pulsed electrical signal and a reset signal issued from the n base counter after n base counting. On/off control
a second bistable multivibrator that causes the third integrator to integrate the reference voltage;
A controller that sends the integrated voltages of the first and second integrators to the A/D converter until the reset signal is generated, and sends the integrated voltages of the third integrator to the A/D converter after the reset signal is generated. A heart rate monitor, characterized in that the A/D converter is configured to send out the A/D converter.