ULTRASONIC TRANSDUCER Russian patent published in 2008 - IPC H04R17/00 

FIELD: physics.

SUBSTANCE: proposed ultrasonic transducer comprises series-connected piezoactive element, quarter-wavelength layer and a thin layer, thickness of which is considerably less than the wavelength of ultrasound in the material of that layer, satisfying, along with the material of the piezo-element and the quarter-wavelength layer, the condition: Z₁>Z₂>Z₃>Z₄, where Z₁ is the wave resistance of the material of the piezoactive element, Z₂ is the wave resistance of the material of the thin layer, Z₃ is the wave resistance of the material of the quarter-wavelength layer, Z₄ is the wave resistance of air. The transducer also has a plate with through-openings, the diameters, distance between the openings, and the thickness of the plate has ratio to the wavelength of ultrasound in the material of the plate, which lies in the 0.1-0.01 range. The wave resistance of the plate is more than the wave resistance of the material of the thin layer. The plate and the quarter-wavelength layer are put into a pipe, the length of which, on the section from the plate to the end of the pipe, satisfies the expression l=nλ/2, where I is the length of the pipe, n is the number of oscillations in the ultrasonic pulse, λ is the wavelength of ultrasound in air. The thin layer is fixed to the quarter-wavelength layer, and the plate with through-openings is put in front of the thin layer and can move relative it in the axial direction at a distance, which lies between zero and a value, equal to the wavelength of ultrasound in air.

EFFECT: increased sensitivity.

2 cl, 3 tbl, 2 dwg