SU1512562A1 - Rheograph - Google Patents

Abstract

The invention relates to medical technology. The goal is to improve measurement accuracy. The rheograph contains two pairs of electrodes 1.2 and 3.4, an alternating current generator 5 consisting of a master oscillator 6 and a voltage-current converter 7, a series-connected differential amplifier 8, a detector 9, an amplifier 10, and a compensation unit 11 consisting from the serially connected module 12 allocation module, Schmitt trigger 13, block 14 tracking-storage with an integrating element 15 and the modulator 16, as well as the low-pass filter 17 and the recorder 18. Improving the measurement accuracy is provided by automatic compensation of the constant component impedance with impulse compensation voltage compensation. 1 il.

Description

ten

17

18

one

3

15

13

3151

The invention relates to medical technology, namely to hemodynamic examination devices.

The purpose of the invention is to improve the measurement accuracy by automatically compensating for the constant impedance.

The drawing shows a structural diagram of a reograph,

Rheograph contains two pairs of electrodes 1, 2 and 3, 4, alternator 5 generator, consisting of series-connected master oscillator 6 and voltage-current converter 7, series-connected differential amplifier 8, detector 9, amplifier 10 and compensation block 11 consisting of a sequentially connected block 12 of the signal module, a Schmitt trigger 13, a tracking-storage block 14 with an integrating link 15 and a modulator 16 whose output is connected to the second input of the detector 9, and the second input to the output / master oscillator 6 as well as a series connection of a lowpass filter 17 and rngist- Rhatore 18, wherein the entrance filter 17 is connected to the output of amplifier 10.

The detector 9 is made in an annular circuit, which allows reducing the noise level in the eographically signal

Reograf works the following way.

The high frequency current through the electrodes 1 and 2 probes the investigated area. From electrodes 3 and 4, a voltage proportional to the impedance of the test section consisting of a constant component of the base impedance and a variable component proportional to the amount of change in blood supply is supplied to the input of the differential amplifier 8. The amplified voltage is applied to the first input of the detector 9. In addition, the second input of the detector 9 is supplied with a compensation voltage from the output of the modulator 16, to the second input of which from the master oscillator 6 of the source current is applied to a high frequency voltage. From the output of the detector 9, a voltage proportional to the variable component of the impedance is fed through the amplifier 10 to a low-pass filter 17, from which output the rheographic signal to the recorder 18 is taken.

The compensation of the constant component of the impedance of the described rheograph is carried out using a feedback circuit, which operates as follows.

From the output of amplifier 10, a voltage proportional to the difference of the signals applied to the first and second inputs of the detector 9 is supplied to the module 12 for extracting the module. A signal from the output of block 12 in the module, proportional to the absolute value of the output voltage of amplifier 10, is fed to the input of a Schmitt trigger 13.

When the threshold of the Schmitt trigger 13 that determines the accuracy of the compensation of the constant component of the impedance is exceeded, a voltage is opened at its output, which opens the tracking-tracking unit 14. In addition, the capacitor of the integrating link 15 starts charging. The voltage of the capacitor of the integrating link 15 through the tracking unit 14 is fed to the first input of the generator 6, the charge of the capacitor of the integrating link 15 flows until the input Schmitt trigger voltage 13 reaches it a trip threshold corresponding to compensation of a constant impedance component. The time constant of the integrator 15 is chosen sufficiently short in view of the possibility of filtering out the components of transients in the filter 17 of the lower

frequencies.

I - ..

The use in the rheograph of automatic compensation of the constant component of the impedance with the pulse adjustment of the compensation voltage improves the accuracy and quality of the research, since the compensation applied is practically inertia-free, and at the output of the rheograph the error signal is compensated for significantly less than the amplitude of the reogram.

Claims (1)

Invention Formula A reogograph containing a series-connected alternator, two pairs of electrodes, a differential amplifier, a detector, an amplifier, a low-pass filter and a recorder, as well as a constant impedance compensation unit. 15125626 denounced by the fact that, with the output of the amplifier, trigger for the purpose of measuring the accuracy of Schmitt, a tracking unit-storage with an innie by an automatic compensation-integrating link and a modulator, the repetition of the constant component of the impedance, whose input is connected to the secondary, the compensation unit contains the following alternator output and an output current block, and an output to the second input of a voltage demodule, the input of which is a co-detector.