JPH0486013A - Ultrasonic solid-state delay line - Google Patents

Abstract

PURPOSE:To attenuate spurious wave by applying an ultrasonic absorbing member, which attenuates and removes spurious waves, in an embedded part. CONSTITUTION:An ultrasonic absorbing member 15 is applied in a recessed part 14. Therefore, a part of spurious 16 of a longitudinal wave 8, which is radiated from an input transducer 10 and made incident on an angle almost parallel to main boundary faces 12 and 13, is converted in a longitudinal/lateral wave mode to a lateral wave 9 sharply changing the angle. Therefore, since the lateral wave 9 is made incident on the main boundary faces 12 and 13, namely, to the ultrasonic absorbing member 15 at a small angle beta, the spurious wave 16 is absorbed and removed by the high absorbing effect of this ultrasonic absorbing member 15. Thus, the spurious wave poor in characteristic can be attenuated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic solid-state delay line, and particularly to a high-frequency ultrasonic solid-state delay line that has good characteristics, is easy to manufacture, and has low cost.

[Prior art] Low-frequency ultrasonic solid-state delay lines have been known for some time (
(Japanese Patent Publication No. 47-27574, Japanese Patent Publication No. 46-22818, US Pat. No. 3,581,247). In these low-frequency ultrasonic solid-state delay lines, a polygonal multiple reflection surface is formed, and an input transducer and an output transducer are arranged on the reflection surface. The spurious is absorbed or diffusely reflected by an absorbing material or a diffused reflection surface provided on the main boundary surface perpendicular to the reflecting surface.

Nowadays, for example, high-definition televisions require ultrasonic solid-state delay lines with an extremely high center frequency of, for example, 100 M) Iz.

For this reason, JP-A-61-288511, JP-A-62-
As shown in Publication No. 18812, using a transverse bulk wave, the thickness of the delay medium is adjusted to the thickness of the output transducer so that the expanded waves such as side lobes are not reflected and become spurious. It was thick.

In such an ultrasonic solid-state delay line, spurious waves are more likely to occur due to the thicker part of the delay medium than in the output transducer, and the wave incident on the main interface of the delay medium has a large angle of incidence, so it is difficult to use a temporary absorption material. Even if it is attached, the absorption effect is weak and it is easy to reflect as it is, and the retardation medium becomes thick, and
The cost is high because each piece is manufactured individually.

Therefore, in order to solve this problem,
No. 88511 and Japanese Unexamined Patent Publication No. 18812/1988 disclose an input transducer in which a polygonal multiple reflection surface is formed in an ultrasonic solid delay medium and a longitudinal wave is emitted from a part of the reflection surface, and a transducer in which a longitudinal wave is An ultrasonic solid state delay line is disclosed having a longitudinal-to-transverse-wave conversion and an output transducer for injecting the transverse-to-longitudinal converted longitudinal wave at another reflective surface.

As shown in FIGS. 7 and 8, these reflective surfaces 20 to 2
On the entire surface of the main boundary surface 25.26 perpendicular to the main boundary surface 25.2, the spurious of the longitudinal wave radiated from the input transducer 27 becomes A sound wave absorbing material 28 is applied. Alternatively, the two parallel main interfaces 25,26 are provided with ultrasound diffuse reflection regions that diffusely reflect the longitudinal wave spurious emitted from the input transducer 27 at the main interfaces 25,26.

[Problems to be Solved by the Invention] However, in such an ultrasonic solid delay line, the ultrasonic absorbing material 28 tends to sag on the edge portion 17, and the reflecting surface 20-2
There is a problem that the ultrasonic wave reflecting portion on the surface of 4 may be covered, and the edge portion is easily damaged during rough polishing, resulting in deterioration of characteristics and an increase in spurious waves.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional difficulties, and it is an object of the present invention to provide an ultrasonic solid-state delay line that has good characteristics, is easy to manufacture, and is capable of attenuating spurious waves at low cost. It is something.

[Means for Solving the Problems] In order to achieve such objects, the ultrasonic solid-state delay line of the present invention provides a polygonal multi-reflection type ultrasonic solid-state delay line formed by forming a plurality of reflecting surfaces. an input transducer that converts an input electrical signal into a longitudinal ultrasonic signal and radiates it to the ultrasonic solid delay medium, and a longitudinal wave propagated through the ultrasonic solid delay medium, on the transducer junction surface of the medium; An ultrasonic solid-state delay line to which an output transducer for converting an ultrasonic signal into an electrical signal is attached, wherein a concave portion is formed on at least one surface of a main boundary surface orthogonal to the transducer bonding surface, and the concave portion The portion is coated with an ultrasonic absorbing material that absorbs spurious signals incident on the main boundary surface.

[Effect] At least a part of the longitudinal wave spurious emitted from the input transducer and incident at an angle close to parallel to the main boundary surface is converted into a longitudinal wave-transverse wave mode and becomes a transverse wave with a large angle change, and the spurious wave enters the main boundary surface at an angle close to parallel. That is, spurious waves incident on the ultrasonic absorber at a small angle are absorbed and removed by the ultrasonic absorber with a large absorption effect. Since the ultrasonic absorbing material that attenuates and eliminates spurious waves is applied inside the embedded part, the ultrasonic absorbing material will not hang down on the edges and cover the ultrasonic reflecting part on the multiple reflection surface, and the characteristics will be improved. This makes it possible to attenuate spurious signals.

[Example] Preferred embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 to 3, the ultrasonic solid state delay line of the present invention is a hexagonal multi-reflection type ultrasonic solid body, such as glass, formed with a plurality of reflective surfaces 3.5.6.7. It consists of a delay medium 1. In the illustrated example, the multiple reflection surfaces 2 to 7 are formed in a hexagonal shape, but they can be formed in other polygonal shapes depending on the amount of delay of the delay line.

Transducer joint surface 2 of this ultrasonic solid delay medium 1
．． 4 includes an input transducer 10 that converts an input electrical signal into an ultrasonic signal of longitudinal waves 8 and radiates it to the ultrasonic solid delay medium 1; An output transducer 11 that converts a sound wave signal into an electrical signal is attached.

As shown in FIGS. 1-2 and 4, the main interface 12.13 perpendicular to the transducer interface 2.4 has a concave portion 1.
4 is formed, and each concave portion 14 has a main boundary surface 12.
．． 13 is coated with an ultrasonic absorbing material 15 that absorbs spurious signals 16 incident thereon. In the illustrated example, concave portions 14 are formed on both sides of the main boundary surface 12.13, and the ultrasonic absorbing material 15 is applied to each concave portion 14, but the ultrasonic absorption effect is small. If the main boundary surface 12.13 has a concave portion 14 on at least one side,
The recessed portion 14 may be coated with an ultrasonic absorbing material 15.

In digging the concave portion 14 in the main interface 12.13,
It can be easily formed by interposing abrasive grains of about #300 using an ultrasonic processing machine or the like. If this concave portion 14 is formed on the main boundary surface 12.13, #
By using abrasive grains of about 300, the concave portion 1
The surface of 4 is smoothed to such a degree that the spurious signal 16 of the longitudinal wave 8 radiated from the input transducer 10 is diffusely reflected.

As the ultrasonic absorbing material 15 applied inside the recessed portion 14, plasticine such as epoxy resin can be used.

The input transducer 10 and the output transducer 11 are substantially the same thickness as the ultrasonic solid state delay medium and are orthogonal to the main interface 12.13.

According to the ultrasonic solid state delay line configured in this manner, the input electrical signal is converted into a longitudinal wave 8 ultrasonic signal by the input transducer 10 attached to the transducer joint surface 2 of the ultrasonic solid state delay medium 1. The longitudinal wave 8 radiated from the input transducer 10 to its surface at 90° propagates in the ultrasonic solid state delay medium 1.

This longitudinal wave 8 is converted into a longitudinal wave and a transverse wave at another reflecting surface 5, and is bent as a transverse wave 9 and propagates toward another reflecting surface 7.

The manner of propagation of this ultrasonic signal will be explained with reference to FIG.

When a longitudinal wave 8 is incident on the interface 5 between the solid medium (2) and the fluid medium (2) at an angle α, a transverse wave 9 appears in addition to the longitudinal wave 8a as reflected waves. The reflection angle α of longitudinal waves is equal to the incidence angle α, but the reflection angle β of transverse waves is different. The relationship between the reflection angles in the reflections of Kosai 1 and others is Sin a /Sinβ=Cpl/Cs
It becomes l. Note that Cpl is the propagation speed of longitudinal waves in medium I,
CsI is the propagation velocity of the transverse wave in the medium 1.

The ratio of the amplitudes of the incident longitudinal wave 8 and the reflected longitudinal wave 8a depends on the incident angle α using the Poisson's ratio of the medium (1) as a parameter, and there is an incident angle at which the amplitude of the reflected longitudinal wave 8a becomes O (zero). At an incident angle where the amplitude of the reflected longitudinal wave 8a becomes 0, the incident longitudinal wave 8 is completely converted into a transverse wave 9. For example, if the medium I is quartz glass with a Poisson's ratio of approximately 0°14, a fluid medium ■, or air, the amplitude of the reflected longitudinal wave 8a is O at an incident angle α of approximately 45°.
Then, the incident longitudinal wave 8 is completely converted into a transverse wave 9.

The reflection angle β of this transverse wave 9 is about 30°. The reflection angle α of the longitudinal wave and the reflection angle β of the transverse wave in FIG. 3 correspond to those in FIG. 6.

This transverse wave undergoes transverse wave-longitudinal wave conversion on the reflecting surface 7, which is the opposite of the above conversion, is subjected to longitudinal wave-transverse wave conversion on the reflecting surface 5, undergoes total reflection of the transverse wave on the reflecting surface 6, and further undergoes transverse wave conversion on the reflecting surface 7. - Longitudinal waves 8 which are subjected to longitudinal wave conversion, longitudinal wave-to-transverse wave conversion at the reflecting surface 5, and transverse-longitudinal wave conversion at the reflecting surface 7 are transferred to an output transformer attached to the transducer joint surface 4 of the ultrasonic solid delay medium 1. The ultrasonic wave signal is incident on the surface of the detector 1 at 90 degrees, and converts the ultrasonic signal of the longitudinal wave 8 into an electrical signal.

As mentioned above, in the ultrasonic solid state delay line according to the present invention, since the input transducer 10 and the output transducer 11 have the same thickness as the ultrasonic solid state delay medium, the output transducers 10 and 11 are different from Omoto. Since it emits a mode wave, it has substantially no function, so it is easy to construct a non-dispersive mode delay line. However, the second and fourth
As shown in the figure, waves almost parallel to the main boundary surfaces 12 and 13 are generated, resulting in a spurious signal 16.

For this reason, in the present invention, a concave portion 14 is formed in the main boundary surface 12.13 perpendicular to the transducer joint surface 2.4.
A spurious signal 16 of the longitudinal wave 8 emitted from the input transducer 10 is converted into a longitudinal wave and a transverse wave in the recess 14. The ultrasonic absorbing material 15 is incident on the recess 1.
4, so the input transducer 10
The spurious wave 16 of the longitudinal wave 8 radiated from the main interface 12.13 and incident at an angle close to parallel to the main boundary surface 12.13 is at least partly converted into a longitudinal-transverse wave mode and has a large angle change, as explained in Fig. 6. The transverse wave becomes 9, and the main boundary surface 12.13
, that is, since it is incident on the ultrasonic absorbing material 15 at a small angle β,
Spurious waves 16 are absorbed and removed by this ultrasonic absorber 15 with a large absorption effect. Note that even if this spurious wave is not removed by one reflection at the main boundary surface 12.13, it is removed by repeating several reflections at the main boundary surface 12.13.

In addition, when forming this concave portion 14 on the main boundary surface 12.13, by using abrasive grains of about 1300 using an ultrasonic processing machine or the like, the surface of the concave portion 14 is free from radiation from the input transducer 10. Spurious signal 1 of longitudinal wave 8
6 is smoothed to such a degree that it is diffusely reflected, the main boundary surface 12.1 is emitted from the input transducer 10.
The spurious signal 16 of the longitudinal wave 8 incident at an angle close to parallel to the waveguide 3 is diffusely reflected on the surface of the concave portion 14, and the spurious wave is attenuated.

Note that since the input transducer 10 and the output transducer 11 are perpendicular to the two parallel main boundary surfaces 12.13, the rectilinear wave radiated from the input transducer 10 is transmitted between the main boundary surfaces 12.13. , and enters the output transducer 11 .

In this way, in the present invention, since the ultrasonic absorbing material 15 for attenuating and removing spurious waves is applied inside the concave portion 14, the ultrasonic absorbing material 15 hangs on the edge portion 17, and the reflecting surface 5.6
．． It does not cover the ultrasonic reflection part 19.19... on the An ultrasonic solid state delay line can be constructed.

According to experiments, the ultrasonic absorbing material 15 is simply attached to the main interface 12.
As shown in Fig. 5(a), the frequency characteristics of the ultrasonic solid-state delay line painted in Fig. 13 have a noticeable presence of spurious components.
When the ultrasonic absorbing material 15 was applied inside the concave portion 14 as in the present invention, spurious waves could be significantly attenuated as shown in FIG. 5(b).

[Effects of the Invention] As is clear from the above embodiments, according to the ultrasonic solid delay line of the present invention, a polygonal multi-reflection type ultrasonic solid delay medium transducer formed by forming a plurality of reflecting surfaces can be used. At the joint surface, there is an input transducer that converts the input electrical signal into a longitudinal ultrasonic signal and radiates it to the ultrasonic solid delay medium, and an electric converter that converts the input electrical signal into a longitudinal wave ultrasonic signal and radiates it to the ultrasonic solid delay medium. An output transducer to be converted into a signal is attached, and a concave portion is formed on at least one surface of the main boundary surface perpendicular to the transducer junction surface, and this concave portion absorbs spurious signals incident on the main boundary surface. Since it is coated with an ultrasonic absorbing material, it can completely absorb spread waves such as side lobes, and only straight waves can be used, which has good characteristics and can attenuate spurious waves.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an ultrasonic solid state delay line according to the present invention;
The figure is a sectional view taken along the line nn in Figure 1 of the same delay line, Figures 3 and 4 are explanatory diagrams of the operation of the same line, Figure 5 (a) is a frequency characteristic diagram of the same delay line, Figure (b) is a frequency characteristic diagram of a conventional delay line, Figure 6 is an explanatory diagram of the operation of the ultrasonic solid state delay line according to the present invention, Figure 7 is a perspective view of the conventional delay line, and Figure 8 is the figure 1. n
-n line sectional view. 1... Ultrasonic solid delay medium 3.5.6.7... Multiple reflection surface 2.4... Transducer junction surface 8... Longitudinal wave 10... Input transducer 11... Output Transducer 12. 3...Main boundary surface 4...Concave portion 5...Ultrasonic absorbing material

Claims (1)

[Claims] The input electric signal is converted into a longitudinal wave ultrasonic signal at the transducer junction surface of a polygonal multi-reflection type ultrasonic solid-state delay medium formed by forming a plurality of reflecting surfaces, and the ultrasonic solid-state delay medium is generated. An ultrasonic solid-state delay line having an input transducer for radiating to a medium and an output transducer for converting an ultrasonic signal consisting of a longitudinal wave propagated through the ultrasonic solid-state delay medium into an electrical signal, the transducer A concave portion is formed on at least one surface of the main boundary surface perpendicular to the Jusa joint surface, and the concave portion is coated with an ultrasonic absorbing material that absorbs spurious signals incident on the main boundary surface. Features an ultrasonic solid delay line.