JPH0758877B2 - Ultrasonic solid delay line - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an ultrasonic solid-state delay line, and in particular, it has excellent characteristics, is easy to manufacture, and is low in center frequency, for example, about 100 MHz. Related to high frequency ultrasonic solid delay line.

[Technical Background of the Invention] Low-frequency ultrasonic solid-state delay lines have been conventionally known (Japanese Patent Publication Nos. 47-27574 and 46-22818, USP 3,5).
81,247). These low-frequency ultrasonic solid delay lines form polygonal multiple reflection surfaces, and as shown in FIG.
An input transducer 32 and an output transducer 33 are arranged in the above, and generally, a transverse bulk wave is used, and its spurious is provided on the main boundary surfaces 34 and 35 which are orthogonal to the reflecting surface. It is absorbed or diffusely reflected by the surfaces 36 and 37.

By the way, recently, for example, in high definition television
Ultrasonic solid-state delay lines with a center frequency of 100 MHz are required.

For this reason, similarly, using the transverse bulk wave, the thickness t of the delay medium M is input to such an extent that the expanded wave 38 such as the side lobe is not reflected and spurious as shown in FIG. It was thicker than 33.

[Problems of the Background Art] Such an ultrasonic solid delay line is apt to generate spurious due to a portion 39 of the delay medium M which is thicker than the input and output transducers 32 and 33 as shown in FIGS. Since the wave incident on the main interface of the delay medium has a large incident angle,
As shown in the figure, even if the absorber is attached, there is a problem that the absorption effect is thin and it is easy to reflect as it is, the delay medium is thick, and the cost is high because each delay medium is manufactured.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional drawbacks, and is a high-frequency non-dispersive ultrasonic wave having a high center frequency of about 100 MHz that has good characteristics, is easy to manufacture, and is low in cost. It is intended to provide a solid delay line.

[Summary of the Invention] In order to achieve such an object, according to the ultrasonic solid delay line of the present invention, a polygonal multiple reflection surface is formed on the ultrasonic solid delay medium, and a longitudinal wave is formed on a part of the reflection surface. An input transducer for radiating and an output transducer for which a longitudinal wave is longitudinal wave-transverse wave conversion on the other reflecting surface and an incident longitudinal wave is converted on the other side. The input transducer and the output transducer have the same thickness as the ultrasonic solid delay medium, and the longitudinal wave spurious waves radiated from the input transducer are the main boundaries on at least a part of the main boundary surface orthogonal to the reflecting surface. The surface of the surface is provided with an ultrasonic wave absorbing material for longitudinal wave-transverse wave conversion and incident transverse wave.

Embodiments of the Invention Preferred embodiments of the present invention will be described below with reference to the drawings.

In the ultrasonic solid delay line of the present invention, hexagonal multiple reflection surfaces 2 to 7 are formed on an ultrasonic solid delay medium 1 such as glass as shown in FIGS. Part 2,
4, an input transducer 10 that radiates a longitudinal wave 8 (shown by a dotted line) and the longitudinal wave are reflected by the other reflecting surfaces 5 and 7 in the longitudinal wave-
An output transducer 11 for arranging a transverse wave 9 (shown by a solid line) conversion and a transverse wave-longitudinal wave converted longitudinal wave is incident. 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 according to the delay amount of the delay line.

On at least a part of the two parallel main boundary surfaces 12 and 13 which are orthogonal to the reflecting surfaces 2 to 7, in almost the entire surface in the illustrated example, the spurious longitudinal waves radiated from the input transducer 10 are the main boundary surfaces 12. , 13 are provided with ultrasonic absorbers 14 and 15 such as epoxy resin on which the transverse wave converted from the longitudinal wave to the transverse wave is incident.

Input Transducer 10 and Output Transducer 11
Has the same thickness as the ultrasonic solid delay medium (shown as to) and is orthogonal to the main boundary surfaces 12 and 13 (shown as ∠R).

Further, the main boundary surfaces 12, 13 are smoothed to a degree of smoothness obtained by cutting with a slicing machine such as a wafer sawing machine.

According to the ultrasonic solid-state delay line configured as described above, the longitudinal wave 8 radiated at 90 ° from the input transducer 10 arranged on the reflecting surface 2 of the ultrasonic solid-state delay medium 1 is delayed by the delay medium. Propagate through 1. This longitudinal wave is subjected to longitudinal wave-transverse wave conversion on another reflection surface 5 and is bent as another transverse wave 9 to proceed to the other reflection surface 6.

This situation will be described with reference to FIG.

When a longitudinal wave 8 is incident on the boundary surface 5 between the solid medium 1 and the fluid medium II at an angle of α, a transverse wave 9 appears in addition to the longitudinal wave 8a. The reflection angle α of the longitudinal wave is equal to the incident angle α, but the reflection angle β of the transverse wave is different from this. The relationship between the reflection angles of these reflections is Sinα / Sinβ = CpI / CsI. Note that CpI is the propagation velocity of the longitudinal wave in the medium I, and CsI is the propagation velocity of the transverse wave in the medium I.

The ratio of the amplitudes of the incident longitudinal wave 8 and the reflected longitudinal wave 8a depends on the incident angle α with the Poisson's ratio of the medium I as a parameter.
There is an incident angle at which the amplitude of is 0 (zero). This reflected longitudinal wave 8a
At an incident angle at which the amplitude of 0 becomes 0, the incident longitudinal wave 8 is completely converted into the transverse wave 9. For example, when the medium I is quartz glass with a Poisson's ratio of about 0.14 and the fluid medium II is air, the amplitude of the reflected longitudinal wave 8a becomes 0 at an incident angle α of about 45 °, and the incident longitudinal wave 8 becomes a transverse wave 9 completely. The conversion of The reflection angle β of this transverse wave 9 is about 30 °. The longitudinal wave reflection angle α and the transverse wave reflection angle β in FIG. 1 correspond to those in FIG.

This transverse wave undergoes total reflection of transverse wave-transverse wave on the reflecting surface 6, and further, on the other reflecting surface 7, the longitudinal wave that is the transverse wave-longitudinal wave reverse to the above-mentioned conversion is reflected on the reflecting surface 4 of the ultrasonic solid delay medium 1. Output Transducer placed at 11 to 90 on its face
Incident at °.

As described 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 (to) as the ultrasonic solid-state delay medium, the input and output transducers 10, 11 are Since it has substantially the function of transmitting and receiving the mode waves other than the 0 mode, the configuration of the non-dispersive mode delay line is facilitated. However, as shown in FIG. 3, almost parallel waves are generated on the main boundary surfaces 12 and 13 and become spurious 16. In the prior art, this spurious was prevented by the structure shown in FIGS. 7 to 8 as described above, but in the present invention, at least a part of the main boundary surfaces 12 and 13,
In the illustrated example, since the ultrasonic absorbers 14 and 15 are provided on almost the entire surface, the main boundary surface 1 radiated from the input transducer 10
As for the spurious of the longitudinal wave 8 incident at an angle close to parallel to 2 and 13, at least a part of the spurious is −
The transverse wave is mode-converted into a large angle-converted transverse wave 9 (Fig. 4), and the main boundary surfaces 12 and 13, that is, the ultrasonic absorber 14,
Since it is incident on 15 at a small angle β, the spurious wave is absorbed by the ultrasonic absorbers 14 and 15 with a large absorbing effect and removed. Even if this spurious wave is not removed by a single reflection at the main boundary surfaces 12 and 13, the main boundary surface 1
It is removed by repeating several reflections at 2 and 13.

Further, since the main boundary surfaces 12 and 13 are smoothed, this longitudinal wave-transverse wave conversion is smoothly performed.

Since the input transducer 10 and the output transducer 11 are orthogonal to the two parallel main boundary surfaces 12 and 13, the rectilinear wave radiated from the input transducer 10 is between the main boundary surfaces 12 and 13. Go straight on and output the transducer
Incident on 11.

In manufacturing such an ultrasonic solid delay line,
As shown in FIG. 6, a block 40 of the ultrasonic solid delay medium 1 on which polygonal multiple reflection surfaces 2 to 7 (FIG. 1) having previously designed shapes and dimensions are formed is prepared. Tin electrodes 41 and 42 are attached to the reflection surfaces 2 and 4 by vapor deposition. On top of that, an input transformer strip 43 and an output transformer strip 44 are arranged. In this state, the delay time is measured, and the reflection surface 6 is polished by the required amount (main adjustment). This is cut with a slicing machine to obtain each unit 45 having an input transducer 10 and an output transducer 11. At this time, the delay time is measured, and if necessary, the reflecting surface 6 is polished (fine adjustment). Ultrasonic absorber 3 on the main boundary surface of each unit 45
Epoxy resin is bonded as 6, 37 (Fig. 4).

According to such a manufacturing technique, a block of an ultrasonic solid delay medium having a polygonal multiple reflection surface of a predesigned geometrical dimension is provided with an input transducer strip and an output transducer strip. After adjusting the delay time in this state, the whole is cut into each unit, so that the delay time does not become uneven in each unit, and a high-quality ultrasonic solid delay line can be obtained. Further, since the input transducer and the output transducer are cut with the same thickness as the ultrasonic solid delay medium, the construction of the non-dispersive mode delay line is facilitated.

Further, if this block is cut by a slicing machine such as a wafer sawing machine, the main boundary surfaces 12 and 13 will be smoothed.

[Effects of the Invention] As is apparent from the above embodiments, according to the present invention, an input transformer that forms a polygonal multiple reflection surface on an ultrasonic solid delay medium and radiates a longitudinal wave on a part of the reflection surface. An input transducer and an output transducer for inputting a longitudinal wave in which the longitudinal wave is subjected to the longitudinal wave-transverse wave conversion on the other reflection surface and the longitudinal wave subjected to the transverse wave-longitudinal wave conversion on the other reflection surface are arranged, respectively. The output transducer has the same thickness as the ultrasonic solid delay medium, and the longitudinal wave spurious waves radiated from the input transducer on at least a part of the main boundary surface orthogonal to the reflecting surface are longitudinal waves at the main boundary surface. Since the ultrasonic wave absorbing material that is converted into the transverse wave and incident on the transverse wave is provided, it is possible to completely absorb the expanded wave such as side lobes and use only the straight wave, and the characteristic is excellent, and the center frequency is extremely high, for example, about 100 MHz, High-frequency non-dispersive ultrasonic solid delay line can be obtained, the thickness of ultrasonic solid delay medium can be made thin, material is saved, easy to manufacture, high quality ultrasonic solid delay line is provided To be done.

[Brief description of drawings]

FIG. 1 is a plan view of an ultrasonic solid-state delay line according to the present invention, and FIG.
FIG. 4 is a side view of the delay line, FIG. 3 is a side view of the delay line before completion, FIG. 4 is a side view of the delay line after completion, and FIG. FIG. 6 is an explanatory diagram for manufacturing the delay line, and FIGS. 7 to 8 are side views of a conventional delay line. 1 ... Ultrasonic solid delay medium 2-7 ... Multiple reflection surface (2, 4 ... Part of multiple reflection surface 5 ... Other reflection surface 7 ... Still other reflection surface) 8 ... Longitudinal wave 9 …… Transverse wave 10 …… Input transducer 11 …… Output transducer 12,13 …… Main interface 14,15 …… Ultrasonic absorber to …… Same thickness ∠R …… Orthogonal

Claims (1)

[Claims] 1. An ultrasonic solid delay medium (1) is provided with polygonal multiple reflection surfaces (2-7), and a part of the reflection surfaces (2, 7) is formed.
4) Input transducer (1) that emits longitudinal wave (8)
0) and the longitudinal wave (8), which has been subjected to the longitudinal wave-transverse wave conversion at the other reflection surface (5) and the transverse wave-longitudinal wave conversion at the other reflection surface (7), and the longitudinal wave (8). 11) are respectively arranged, the input transducer and the output transducer have the same thickness (to) as the ultrasonic solid delay medium, and the main boundary surface (12, 13) orthogonal to the reflecting surface. At least a part is provided with an ultrasonic wave absorbing material (14, 15) on which a transverse wave (9), which is a longitudinal wave-transverse wave conversion of the longitudinal wave spurious wave radiated from the input transducer, is incident on the main boundary surface. An ultrasonic solid-state delay line characterized by the above.