Foreword

Blood pressure is very main healthy index, what blood pressure measures is accurate the health that mattered to people directly. The country labels tonometer compulsive calibrating metrological implement. Tonometer is based on the mercury that general hospital uses to stalk or branch artificially law of family name sound, this kind of method puts in defect of some of a few solid: The speed that is deflate has immediate effect to reading, speed of international standard deflate is every second 3 ～ 5mmHg, and deflate has different doctor fast slow, can affect metrical accuracy; 2 it is this kind of method move degree to be main basis with chime of the person's vision, hearing, standardize very hard. For this, this design from blood pressure detect the method begins, the MN101EF32D that uses high speed of the company below Japanese pine, low power comsumption is odd a machine, measure as tonometer, control, data is read write, the core that data shows, can use well and truly show wave way (oscillation law) measure blood pressure.

Working principle
Show wave way (oscillation law) it is a basis sleeve belt is in decompression process, the line of sth resembling a net of amplitude change bag of wave of its pressure oscillation will decide of blood pressure. At present more unanimous view is when the amplitude that takes pressure oscillation wave when sleeve is the biggest, the pressure that sleeve takes is artery is average pressure. Arterial systole presses correspondence to include the first inflection point of line of subsidiary channels in the human body through which vital energy at amplitude, diastolic pressure is corresponding the 2nd inflection point at line of bag sth resembling a net.

Hardware design
The system works basically the principle is shown 1 times like the graph. The voltage signal that pressure sensor outputs is passed above all low a filter filter wave, circuit is put to suit signal translate into sheet by carry later piece the input signal of machine, pass simulative sampling signal MN101EF32D sheet finally piece amount of number of machine translate into. The program undertakes the analysis after digital filter wave to collection data, the " of diastolic pressure of " of two crucial index that computation gives human body blood pressure and " systole press " , later odd a machine go to data storage instantly in exterior memory, show these important data go up in LCD.

Sensor carry on reachs the design of its periphery circuit

The sensor that this tonometer uses presses block type pressure sensor for MPS-3100-006G, it is the benefit type bridge that constitutes by 4 equivalence resistor, its output voltage and input pressure to become direct ratio, when good position falls to be inputted when pressure, resistance follows a change, but actually the change of temperature also can affect its block to be worth output result. Additional, because crystal and circuit design made error, add the effect that encloses the respect such as the process, zero shift is not 0. Must be undertaken by extra element individual temperature compensates circuit so corrective. Its are important index is as follows:
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