Naida S. Theory and project of broadband electro-acoustic paths for medical devices

The thesis is devoted creation of methodical basis for a calculation and planning of broadband electro-acoustic paths for medical devices. Optimization of the systems, the band of frequencies of which is comparable with greater from partial frequencies, on a maximum of band carried out analytically by the model of the coupled contours, that allowed to formulate principles of construction of the systems with the wide band of frequencies, different between itself character of damping. The same model is applied and for acoustic-mechanical of the system of middle ear of man taking into accounts an auditory tube. A piezoelectric transducer which is used in vehicles for treatment of row of diseases is offered. After the analysis of possible variants the method of construction and calculation of transducer was chosen with a metallic quarter-wave layer in which the band of frequencies is determined the coefficient of connection with the transformer of layer. The rectangular form of peak frequency description of transformers is got for ultrasonic scanners, which allows carrying out a dynamic frequency scan-out and filtration of echo-signal more narrow band the middle frequency of which diminishes in time in accordance with the depth of sounding; to apply one transducer in all of working range of medical ultrasonic diagnostics. The theory of middle ear of man is created. Taking advantage of method of drafting of equivalent charts, what before for an ear not done, it has been shown that an equivalent chart of middle ear is two coupled contours, partial frequencies of which differ almost three times. On the basis of equivalent chart got in theory and confirmed experimentally decoding of results of tympanometry on the method of author formula for the parameter of norm of middle ear. On the basis of experimental information about the size of active constituent of acoustic impedance of middle ear principle of reflection of sound from an ear-drum, which follows from it, was formulated in a norm.