JPH03171899A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE:To stabilize effective performance by providing trigonal pyramids on the surface of a member, and filling up their void part with the material of impedance close to that of a medium. CONSTITUTION:The trigonal pyramids 11 are formed on the surface of a trans ducer itself or the member 10 connected to the transducer, and the void part is filled up with the material of the sound impedance close to that of the medi um. Accordingly, by changing the occupancy rates of the transducer side and the medium side of planes S1 to S4 perpendicular to the advancing direction of an ultrasonic signal successively from low sound impedance to high sound impedance, the loss of the energy from the transducer to the final medium due to the mismatch of the sound impedance can be suppressed minimum. Thus, the ultrasonic sensor of high efficiency can be obtained.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an ultrasonic sensor.

(Prior technology) A polymeric material such as silicone 1T fat mixed with metal powder that has an impedance close to that of the transducer is poured onto the surface of the transducer as a filler, and the resin is gently cured. It was common knowledge that the degree of filler distribution should be high on the transducer side and low on the medium side, but it is important to keep the concentration of the polymer resin uniform and at the same time to maintain an appropriate distribution of the filler. It was extremely difficult to completely cure the resin, and as a result, it was not possible to provide a stable ultrasonic sensor as a product.

(Problems to be Solved by the Invention) The purpose of the present invention is to stabilize the manufacturing process of ultrasonic sensors, and in particular, to stabilize the manufacturing process of ultrasonic sensors. Alternatively, it is intended to stabilize the effective performance by suppressing variations in deterioration caused by mismatching of acoustic impedance due to water or the like.

As is well known, the cause of acoustic impedance mismatch is that the difference in acoustic impedance between the transducer and the medium is quite large. It is also well known that it is a good idea to place it in between.

However, there is no specific way to properly match these, and as mentioned above, this is done by extremely primitive means.

In the present invention, as a typical example thereof is shown in a vertical cross-sectional view in the figure, a triangular pyramid 11 is established on the surface of the transducer itself or a member 10 joined to the transducer, and the cavity is used to adjust the acoustic impedance of the medium. Fill with similar materials.

(Function) With the current machining technology, it is extremely easy to create a triangular profile with high mechanical precision for the material on the transducer side, and the reproducibility is also high. In addition, from the viewpoint of processing costs, it goes without saying that the precept molding made by a group mold is also highly accurate and reproducible.

The triangular pyramid of the transducer-side member processed in this way is filled with a material close to the acoustic impedance of the medium, and a surface s l+ s l+ s 1+ s perpendicular to the direction of propagation of the ultrasonic signal as shown in the figure is formed. ．． The occupancy ratio of the transducer side and the medium side is sequentially changed from low acoustic impedance to high acoustic impedance, and energy from the transducer is transferred to the final medium by minimizing loss due to acoustic impedance mismatch and improving efficiency. Obtain a good ultrasonic sensor.

(Example 1) Ceramic piezoelectric material was used as a transducer, a metal plate was provided on the side in the direction of propagation of the ultrasonic waves, and a triangular pyramid with a height of about 2 mm was made on the surface by knurling.
Good results were obtained by filling silicone resin thereon to a thickness of about 2.5 mm.

(Example 2) Using a polarized piezoelectric material as a transducer,
Next, when a triangular pyramid is created using diamond foil on a piezoelectric ceramic material that has not been subjected to polarization treatment as the member 10, and then filled with silicone resin in the same way as in the former case, good results similar to those of the previous example can be obtained. Can be done.

The ultrasonic sensor according to the present invention is capable of mechanically controlling acoustic impedance adjustment with high precision, and is extremely effective and valuable industrially.

[Brief explanation of the drawing]

The drawing shows a typical example of the present invention in a vertical cross-sectional view.

Claims (1)

[Claims] The transducer side has a high occupancy rate of a material with an acoustic impedance equal to or close to that of the transducer, and the occupancy rate decreases as it approaches the medium side, and the occupancy rate of a material with an acoustic impedance equal to or close to that of the medium is occupied. Ultrasonic sensor characterized by increasing rate.