SU930145A1 - Analog frequency meter - Google Patents

Description

The invention relates to medical equipment, in particular to analog heart rate meters, and can be used in continuous patient monitoring systems and in sports medicine for measuring instant or average heart rate values.

At the known gauges time _s pulse rate "based on the measurement of the pulsation period and converting this value into a frequency per minute, containing the power supplies, conditioners, keys [1].

However, these devices have low reliability.

The closest in technical essence to the proposed one is a device containing a driver, the output of which is connected to the inputs of the first and second single vibrators, the outputs of the latter are connected to the first inputs of the first and second electronic keys, the second input of the first electronic key is connected to one of the poles of the power sources, and the output is connected to the second input of the second electronic key E2].

A disadvantage of the known device is low reliability.

The purpose of the invention is to increase the reliability of the device.

This goal is achieved by the fact that an 8 analog frequency meter containing a driver, the output of which is connected to the inputs of the first and second single vibrators, the outputs of the latter are connected to the first inputs of the first and second electronic keys, the second input of the first electronic key is connected to one of the poles of the power source, and output - with the second input of the second electronic key, two capacitors, a resistor, a source follower and a measuring device, are introduced, and the resistor is connected in parallel with the first capacitor, one lining of which The device is connected to the output of the first electronic key, and the other lining to the connection point of the other pole of the power supply, the first input of the measuring device and one lining of the second capacitor, the other lining of which is connected to the output of the second electronic key and with the control input of the source repeater, the other input of which is connected to the second input of the first electronic key, and the output to the second input of the measuring device.

In FIG. 1 is a structural diagram of a portable analog heart rate monitor; in FIG. 2 is a timing chart explaining the operation of the heart rate monitor.

The device comprises a driver 1, single vibrators 2 and 3, electronic keys 4 · and 5, a power supply 6, a source repeater 7, a measuring torus 9 and 10 It works at once.

The front shaper 1 of the measured frequency pulse starts single vibrators 2 and 3. Single vibrator. 2 forms a pulse of stable duration (Fig. 26 willow), during which the first capacitor 9 is charged through the electronic switch 4 to the voltage of the source 6.

At the end of the pulse of the one-shot 2, the electronic switch 4 opens and the first capacitor 9 is discharged through the resistor 11 (Fig. 2, d) until the next pulse of the measured frequency F \ arrives according to the law

U ^ (t) = U pit ^e &

formed front (1)

At the moment of arrival of the next generated pulse (Fig. 2, q), the electronic key 5 is opened for a short time from the one-shot 3. During this time, the voltage U ₄ on the capacitor 9 is transmitted to the second capacitor 10. This voltage is transmitted through the source follower 7 to the measuring device 8, which is calibrated in units of measured frequency. In FIG. 2t, it is shown that with a decrease in the instantaneous value of the measured frequency (Fig. 2, a), the voltage at the secondary device also decreases (Uq).

where <0 ⁴ „

So, for the measured frequency, taking into account (1), we can write r 4 ·, pgt GT - Char rsp __4. -, (Q.) ^T charge ^{+ s} 4 ^to Vma ^{+ c} \ ^Re n 1/7 Tdddrsp the duration of the output pulse of one-shot 2;

- capacitor capacitance 9;

- resistance of the resistor 11;

- charge voltage of the capacitor 9.

_t then UcMP- Unur

4dP „' ^T Pcn * Kn --- In formula (2), all quantities turn out to be constant, therefore (2) we can ^C T

Uc IU us and a rewrite where K = ^{t + C} 1 Ear ^{Ke "and} ^ ^{and T}

By appropriate selection of the time constant C ^ R, it is possible to minimize the approximation error of the function F _x = 1 / Tu by the function F _x = = 1 / (K <-C ₄ R0 _h 1 / U _x ) at a certain interval of the measured frequencies.

! Thus, the readings of the device 8 (taking into account the calm time of the device) correspond to the instantaneous value of the heart rate. If a capacitor is connected in parallel with the secondary device 8, then its readings will correspond to the average value. Instead of measuring device 8, in principle, you can connect a recorder and then we will have information about the change in heart rate over time.

The proposed device has a systematic component of the error due to the finite duration of the output pulse of the one-shot 3, the capacitor 10 is slightly larger than the capacitor 9 (Fig. 2, t, ka A). But this phenomenon can be taken into account when calibrating the showing boron. In order to reduce this component of the error, instead of a single-vibrator 3, it is practically sufficient, as a result of which the voltage at

930 apply differentiating RC chain.

The discrete part of the proposed device is made on microchips of the MOS structure, which allowed all 5 elements together with an autonomous power source to be placed in the head body of the M 304 device.

Yu

Claims (2)

The invention relates to medical technology, in particular to analog meters of heart rate, and can be used in continuous patient monitoring systems and in sports medicine to measure the instantaneous or average pulse rate. Currently, pulse rate meters are known based on measuring the pulsation period and converting this value to a frequency of beats per minute, which contain power sources, drivers, and HP keys. However, these devices have low reliability. The closest in technical essence to the present invention is a device containing a driver whose output is connected to the inputs of the first and second single vibrators, the outputs of the latter are connected to the first inputs of the first and second electronic keys, the second input of the first electronic key is connected to one of the poles of the power sources, and the output is connected to the second input of the second electronic key 2.. A disadvantage of the known device is low reliability. The purpose of the invention is to increase the reliability of the device. This goal is achieved by the fact that in an analog frequency meter containing a driver, the output of which is connected to the inputs of the first and second single-shot, the outputs of the latter are connected to the first inputs of the first and second electronic switches, the second input of the first electronic clamp is connected to one of the poles of the power supply, output - with the second input of the second electronic key, two capacitors, a resistor, a source follower and a measuring device are inserted, with the resistor connected in parallel with the first capacitor, one cover and whose connection is connected to the output of the first electronic switch, and the other facing to the connection point of the other pole of the power source, the first input of the measuring instrument and one facing of the second capacitor, the other facing of which is connected to the output of the second electronic switch and to the control input of the source follower, the other input of which is connected to the second input of the first electronic key, and the output to the second input of the measuring instrument. FIG. 1 shows a structural diagram of a portable analog pulse meter; in fig. 2 - timing diagrams explaining the operation of the pulsomer. The device contains: it shaper 1, one-shot 2 and 3, electronic keys - And 5 j power supply 6, source follower 7, measuring device 8, two capacitors 9 and -10 and resistor 11 The device works as follows. The one-vibrator 2 and 3 are triggered by the leading edge formed by the shaper 1 of the measured frequency. 2 generates a pulse of stable duration (Fig. 26 IV), during which the first capacitor 9 is charged through the electronic key to the source voltage 6. At the moment of the end of the one-shot 2 pulse, the electronic key.k opens and the first capacitor 9 is discharged through the resistor 11 (Fig. 2, d.) until the arrival of the next pulse of the measured frequency FX according to the law t u. (t) and in the MO (the arrival tape of the next formed pulse (Fig. 2, cf), the electronic vibrator 3 opens for a short time) key 5. At this time, the voltage U on the capacitor 9 is transmitted to the second capacitor 10. This voltage is transmitted through the source follower 7 to the measuring device 8, which is calibrated in units of the measured frequency. Fig. 21 shows that as the instantaneous value of the measured frequency decreases ( 2, and the voltage on the secondary device is also reduced (Ufj). So, for the measured frequency, c (1) can be written with allowance for vH sdP pc (f.e fAe Ti., d, Trs, the duration of the output pulse of the single-oscillator 2; capacitor capacitance 9; resistance of resistor 11; capacitor charge voltage 9Uc-jdr and pit MP., Tpcj-i n jj In formula (2), all values except and are constant values, and therefore (2) can be rewritten as .. By appropriate choice time e, R it is possible to minimize the error of approximation of the function Fy 1 / Т by the function Py 1 / (, 1 / them) on a certain interval of measured frequencies. I Thus, the readings of the device 8 (taking into account the time of the calm of the device) correspond to the instantaneous value of the pulse rate. If a capacitor is connected in parallel with the secondary device 8, then its readings will correspond to the average value. Together with the measuring device 8, in principle, you can connect a recorder and then we will have information about the change in pulse rate over time. The proposed device has a systematic component of the error due to the final duration of the output pulse of the one-oscillator 3, as a result of which the voltage on the capacitor 10 is somewhat greater than condenser 9 (Fig. 2, t, point A). But this effect can be taken into account when calibrating the indicating device. In order to reduce this component error, instead of the single-oscillator 3 it is practically enough 5 to apply a differentiating RC-chain. The discrete part of the proposed device is made on microcircuits of the MOS structure, which allowed all elements together with an autonomous power source to be placed in the housing of the head of the device M 30. Invention Analog frequency meter containing a driver, the output of which is connected to the inputs of the first and second single-oscillator, the outputs of the last connected to the first inputs of the first and second electronic keys; the second input of the first electronic cylinder is connected to one of the poles of the power sources, and the output to the second input of the second the electronic key, which is distinguished by the fact that, in order to increase the reliability, two capacitors, a resistor, a source follower and. 6 Measuring device | Moreover, the resistor is connected in parallel to the first capacitor, one plate of which is connected to the output of the first electronic key, and the other plate to the connection point of the other pole of the power supply, the first input of the measuring device and one plate of the second capacitor, the other plate of which is connected to the output of the second electronic the key and with the control input of the source follower, the other input of which is connected to the e input of the first electronic key, and the output to the second input of the measuring switch set. Sources of information taken into account in the examination 1. Issues of radio electronics. 1971. Ser. general technical, vol. 20 s. 63. 2.Kirianaki N.V. and Dudykevich V.B. Methods and devices for digital measurement of low and infra-low frequencies. Lviv, Vishcha school -, 1975, p. 9b, fig. 3-7. Yu "VJ e