Ultrasonic transducer, method for manufacturing ultrasonic transducer, and ultrasonic flowmeter
It is an object of the present invention to provide an ultrasonic transducer, which is so configured as to reduce the variations in characteristics, thereby to enable the stabilization of the precision, as well as to enable the improvement of the durability, and the like, a method for manufacturing the ultrasonic transducer, and an ultrasonic flowmeter. In order to attain this object, in accordance with the present invention, the ultrasonic transducer is so configured as to include a piezoelectric element and an acoustic matching layer, wherein the acoustic matching layer is made of a dry gel of an inorganic oxide or an organic polymer, and a solid skeletal part of the dry gel has been rendered hydrophobic. With this configuration, it is possible to obtain the ultrasonic transducer having an acoustic matching layer 3 which is very lightweight and has a small acoustic impedance due to the solid skeletal part of the dry gel which has been rendered hydrophobic. Further, it is also possible to obtain the ultrasonic transducer which shows a narrow range of characteristic variations, and is stable due to the high homogeneity of the dry gel.
1. A method for manufacturing an ultrasonic transducer comprising an acoustic matching layer made of a dry gel of an inorganic oxide or an organic polymer, the solid skeletal part of the dry gel having been rendered hydrophobic, a gas shielding case having an inner surface and an outer surface, and a piezoelectric element mounted on said inner surface of said gas shielding case, the method comprising:
applying a gel raw material solution to the outer surface of said gas shielding case to thereby deposit said gel raw material solution on said outer surface,
said outer surface of said gas shielding case and said gel raw material solution comprising components capable of chemically bonding with one another;
solidifying the gel raw material solution to obtain a wet gel; and
removing solvent in from the wet gel to obtain a dry gel acoustic matching layer.
2. The method for manufacturing an ultrasonic transducer according to claim 1 , wherein a protective layer is formed on the surface of the acoustic matching layer by a dry deposition method.
3. A method for manufacturing an ultrasonic transducer comprising an acoustic matching layer made of a dry gel of an inorganic oxide or an organic polymer, the solid skeletal part of the dry gel having been rendered hydrophobic, a hermetically sealed case having an inner surface and an outer surface, and a piezoelectric element mounted on said inner surface of said hermetically sealed case, the hermetically sealed case having an acoustic matching layer mounting part in concave form with a depth which is a quarter of the ultrasonic oscillation frequency at said outer surface, the method comprising:
applying a gel raw material solution to the outer surface of said hermetically sealed case to thereby deposit said gel raw material solution on said outer surface,
said outer surface of said hermetically sealed case and said gel raw material solution comprising components capable of chemically bonding with one another;
solidifying the gel raw material solution to obtain a wet gel; and
removing solvent from the wet gel to obtain a dry gel acoustic matching layer.