JPH01261012A - Many times reflection type ultrasonic wave delay line - Google Patents

Abstract

PURPOSE:To make a fractional band wide and to prevent the disturbance in the frequency characteristic by providing a slot to a mode conversion face in a direction perpendicular to each transducer, applying a sound absorbing agent to the mode conversion face and each side face of a packing member and packing the sound absorbing agent to the groove part. CONSTITUTION:An ultrasonic wave B0 comprising a lateral wave component from an input transducer 13 and an output transducer 14 is converted into an ultrasonic wave signal B1 comprising a longitudinal wave component by mode conversion faces 11A, 11B. The ultrasonic wave signals B1, B1 run against slots 2A, 2B and since the ultrasonic wave absorbing agent 18 is packed in the slots 2A, 2B, the ultrasonic wave signals B1, B1 are absorbed herein, part of them is reflected at a prescribed angle and attenuated. That is, the spurious signal is largely attenuated herein by the operation of the sound absorbing agent 16 packed in the slots 2A, 2B. Thus, the disturbance in the characteristic at a band with a high frequency is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-reflection type ultrasonic delay line in which a backing material is bonded onto an input/output transducer.

[Conventional Technique'#I] In recent years, the transmission band of video equipment has been trending toward wider bands as image quality has improved, and the inventors have previously published patent No. 62-23575.
In the 0@ publication, we have proposed a multi-reflection type ultrasonic delay line that is suitable for such fields and can obtain broadband characteristics with a relatively simple configuration. FIGS. 10 and 11 show a multi-reflection type ultrasonic delay line constructed in this manner.

In FIGS. 10 and 11, 10a to 10d each represent a signal reflecting surface, and 10e represents a transducer coupling surface. On this transducer coupling surface 10e,
Lower surface electrodes 13A and 14A are provided, the input transducer 13 and the output transducer 14 are connected to the upper surfaces of the lower electrodes 13A and 14A, respectively, and each transducer 13.
A reflecting surface (mode conversion surface > 11A, 11B) that modulates and reflects the ultrasonic signal from 14, and an upper surface electrode on which tin is vacuum-evaporated on the coupling surface side with each transducer 13 and 14, respectively. A backing material 11 formed by providing 13B and 14B is joined.

Mode conversion surface 11A of the backing material 11.

11B is the input transducer 1 as shown in FIG.
3. Ultrasonic signal 8 consisting of transverse wave components output from 14
It has a function of converting ゜ into an ultrasonic signal @B2 consisting entirely of longitudinal wave components, and thereby the ultrasonic signal B sent to the backing material 11 side.

is prevented from being converted back into an electrical signal by the input transducer 13,14. Specifically, the 14th
As shown in the figure, an ultrasonic signal B of a transverse wave component is output to the backing material 11 side. Almost all of the spurious signals are converted into longitudinal wave components at the mode conversion surfaces 11A and 11B, and a part of the spurious signal is transferred to the input transducer 13.1 again as shown in FIG.
However, since the input transducers 13 and 14 are transducers for transverse wave signals, they are not converted into electrical signals. As a result, spurious signals, e.g., spurious signals with an odd number of reflections that adversely affect the band characteristics.
The influence of Td, 5Td, etc. is almost completely eliminated.

Here, this reflective surface 11A, that is, the mode conversion surface will be described in detail.

As shown in FIG. 7(b), when a transverse wave Bn is incident on the interface 55 between the multi-piece medium 2 and the fluid medium 2 at an angle α, a longitudinal wave B2 appears in addition to the transverse wave B1 as reflected waves. Reflection angle α of transverse wave
is equal to the incident angle α, but the reflection angle β of the longitudinal wave is different from this. The relationship between the reflection angles in these reflections is as follows: 3inα/Sinβ−C1)I/Csl. Note that Cpl is the propagation velocity of the VT wave in the medium (1), and Csl is the propagation velocity of the longitudinal wave in the medium I.

The intensity of the incident transverse wave β and the reflected transverse wave β1, 8 + / B o, depends on the angle of incidence α using the Poisson's ratio σ of the medium (Fig. 6 (b)) as a parameter, and the intensity of the reflected transverse wave B1 is O (zero).
At the angle of incidence, the incident transverse wave Bo is completely transformed into a longitudinal wave B
A conversion to 2 occurs. For example, if medium 1 is Poisson's ratio 0
．． When the lead glass in No. 22 and the fluid medium ■ are air, the angle of incidence α is
is about 28゛ (this is called the mode conversion angle), the intensity of the incident transverse wave B+ becomes 0, and the incident transverse wave B. is completely longitudinal wave B
A conversion to 2 occurs.

When the incident wave is a longitudinal wave, the relationship between the incident longitudinal wave AON, the reflected reflected wave longitudinal wave, and the transverse wave A2 is as shown in Figure 5 (a), and the intensity A + / A a is the Poisson wave of the medium 1. ratio σ
There is an incident angle at which the intensity of the reflected longitudinal wave A1 becomes 0 (zero), depending on the incident angle α using (FIG. 6(a)) as a parameter.

Medium ■ is lead glass with Poisson's ratio of 0°22, fluid medium ■
When is air, the intensity of the reflected longitudinal wave A1 becomes O when the angle of incidence α is about 55°, and the intensity of the reflected longitudinal wave A1 becomes O. is completely converted into a transverse wave A2.

By the way, in the case of transverse waves, there is a critical angle (see Figure 6 (b) (approximately 37° in the example of Poisson's ratio 0.22)), and if the critical angle is exceeded, mode conversion to longitudinal waves will not occur. The angle of incidence α must be less than or equal to the critical angle.

In this way, the mode conversion surfaces 11A and 11B are
As shown in FIG. 4, the surface is inclined so that the IPi sound wave signal Bo is incident at an incident angle α, that is, a mode conversion angle α.

And on this backing material 11 is shown FIG.

As shown in FIG. 13, an ultrasonic sound absorbing material 16 is applied so as to cover each surface except for the interface between the input and output transducers.

When an electrical signal is input to the input 1 to the transducer 13, the apex acoustic delay line configured in this manner converts the electrical signal into an ultrasonic signal consisting of a transverse wave component. This ultrasonic signal then propagates within the ultrasonic delay medium 10 for a predetermined time (Td).
After this period, the output transducer 14 converts the signal into an electrical signal and sends it to an external device (not shown). In this case, spurious reflections (3Td>, (5Td), etc.) having an odd number of reflections, which have a particularly negative effect on the band characteristics, are caused by the backing material 1.
Due to the action of the mode conversion surfaces 11A and 11B of No. 1, almost all of the ultrasonic signals are converted into longitudinal wave components, so (3Td),
(The influence of spurious signals such as 5Td> is eliminated.

Fig. 15 shows a band characteristic graph of the ultrasonic delay line shown in Figs. 12 and 13, and the center frequency f is 14 [MH2].
These are the experimental results when In this figure, −3[
dB] attenuated point, that is, the point X+ in the figure, is 7.85 [
MH7], X2 point is 20.7 [MH2] r-, Colleniotte, W+--6, 15 [MH2], W2 =
−6,7 [MH2]. Therefore, the fractional band (W/fo
) is W=IW+ l + l W2 l =12.8
5 [MH2], so (W/fl]) = approximately 92[%
], making it possible to easily obtain broadband characteristics.

Note that each transducer 13.1 of the backing material 11
4 and the surface perpendicular to each transducer 13, 14 in the thickness direction of the backing material 11, that is, the surface on which the electrodes 13B, 14B are deposited, are mirror-finished.

(Problems to be Solved by the Invention) However, the ultrasonic delay line according to the above conventional example has a high fractional bandwidth (W/fn) (approximately 92[%]) and can realize a wide band; In the high frequency region (section P), the characteristics are disturbed due to the influence of spurious signals.

Therefore, if the ultrasonic delay line is used in the contour guarantee circuit of a high-definition television system with a video signal band of 30 [1'vlH2] or more, the interference will be disturbed due to the influence of the spurious signal (striped pattern on the screen). This has the disadvantage that it cannot be used in practical high-definition television systems because the image quality deteriorates.

[Object of the Invention] The present invention is suitable for use in high-definition television systems, etc., which can improve the above-mentioned conventional disadvantages, widen the specific band, and eliminate disturbances in frequency characteristics due to spurious signals. An object of the present invention is to provide a multi-reflection type ultrasonic delay line.

[Means for Solving the Problems] Accordingly, in the present invention, the input transducer, the output transducer, and the ultrasonic delay medium are bonded to the opposite surface of each transducer, and each backing is connected from each of the transducers to the A backing material having a mode conversion surface that converts an ultrasonic signal of a transverse wave component incident on the material into an ultrasonic signal of a longitudinal wave component, or converts an ultrasonic signal of a longitudinal wave component to an ultrasonic signal of a transverse wave component. The purpose of the present invention is to achieve the above object by employing this configuration.

[Example] Hereinafter, an example of the present invention will be described based on FIGS. 1 to 5. Here, the same signals are attached to the same components as in the above-mentioned prior art.

In FIGS. 1 and 2, 10a to 10d each represent a signal reflecting surface, and 10e represents a transducer coupling surface. Upper surface electrodes 13A and 14A are provided on this transducer coupling surface 10e, and an input transducer 13.degree.
an upper surface electrode 13B having a reflecting surface (mode conversion surface>11A, 11B) that modulates and reflects the ultrasonic signal from the transducers 13 and 11B, and having tin vacuum-deposited on the coupling surface side with each of the transducers 13 and 14; Backing material 1 provided with 14B
2 are joined. As shown in FIGS. 1 and 2, this backing material 12 has a mode conversion surface 11A with a depth d(i
n) groove (slit>2A) is also the mode conversion surface 11
A groove portion (slit) 2B having a depth of d (am) is provided in the direction perpendicular to the output transducer 14 at B.

Each of the grooves 2A and 2B is filled with an ultrasonic sound absorbing agent 16, and the backing material 12 is filled with the ultrasonic sound absorbing material 16 shown in FIG.
As shown in FIG. 4, an ultrasonic sound absorbing agent 16 is applied so as to cover each surface except for the joint surfaces of the input and output transducers. The rest of the configuration is the same as that of the conventional example described above, so a description thereof will be omitted.

Next, the propagation effect of ultrasonic signals in the backing material 12 will be explained based on FIG. 5.

In FIG. 5, an ultrasonic wave B consisting of a transverse wave component from an input transducer 13° and an output transducer 14 is converted into an ultrasonic signal B1 consisting of a longitudinal wave component at mode conversion surfaces 11A and 11B, as in the conventional example described above. The ultrasonic signals B+, B+ collide with the grooves 2A, 2B as shown. Since the grooves 2A and 2B are filled with the ultrasonic sound absorbing agent 16 as described above, the ultrasonic signals B+ and B+ are absorbed here, and a part of them is further reflected at a predetermined angle and attenuated. . That is, compared to the conventional example, the grooves 2A, 2B
It is thought that the spurious signal is greatly attenuated here due to the action of the sound absorbing material 16 filled in.

FIG. 8 is a diagram showing the frequency characteristics of the ultrasonic delay line according to this embodiment, and the center frequency fQ=14 [MH
2] is the experimental result.

In this figure, -3 [dB] is the attenuated point, 71 in the figure.
The point is 7.85 [MH2], Y2 is 20.7 [MH2]
The fractional band <W/fo) was approximately 92%1, and broadband characteristics could be obtained as in the conventional example. Furthermore, in this example, it was possible to obtain experimental results in which the characteristics were not disturbed in the high frequency region.

Since this embodiment is configured as described above, it is possible to use ultrasonic waves without deteriorating images even when used in contour correction circuits, etc. of high-definition television systems where the video signal bandwidth is 30 [MH2] or more. Can provide delay line.

Note that in this embodiment, one groove portion 2A, 2B was provided on each of the mode conversion surfaces 11A, 11B;
A plurality of grooves may be provided in 11B, or a groove may be provided at the apex where mode conversion surfaces 11A and 11B intersect (see FIG. 9).

[Effects of the Invention] Since the present invention is configured as described above, the ratio band is widened and there is no disturbance in the frequency characteristics due to spurious signals, and the present invention is suitable for use in high-definition television systems, etc. A reflective ultrasonic delay line can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing one embodiment of the present invention.
Front view of the multi-reflection delay line shown in Figures 3 and 4.
The figure is an explanatory diagram showing the backing material of the multi-reflection type delay line shown in Figure 1 coated with a sound absorbing material, Figure 5 is a functional explanatory diagram of the backing material of the delay line shown in Figure 1, and Figure 6 (a)
, (b> and FIGS. 7(a) and (b) are similar to FIGS. 1 and 10.
8 is a diagram showing the band characteristics of the delay line shown in FIG. 1, and FIG. 9 is a diagram showing the delay line according to another embodiment of the present invention. FIGS. 10 and 11 are configuration diagrams of delay lines according to the prior art; FIGS. 12 and 13 are configuration diagrams showing other configurations of line backing materials; FIGS. 12 and 13 are configuration diagrams of delay lines shown in FIGS. FIG. 14 is an explanatory diagram showing the operation of the backing material of the conventional delay line, and FIG. 15 is a diagram showing the band characteristics of the band line of the conventional delay line. . 10... Ultrasonic delay medium 12...
... Backing material 13 ... Input transducer 14 ...
......Output transducer 16...
...Sound absorbing material 2A, 28.4A, 4B, 5A ...Groove 11A, IIB ...Mode conversion surface 43A
, 14A... lower surface electrodes 13B, 14B.
・・・・・・Top electrode Bo・・・・・・Incoming ultrasonic signal B1・・・・・・Reflected ultrasonic signal? !
47 Figure 3 Figure 1θ Figure 4 OC 6th (α), *sb entry pr4! Ji 7th (0L) (b) Figure (b) Figure 4176 Figure 72 1θ @ /3 Figure

Claims (1)

[Claims] The input transducer, the output transducer, and the ultrasonic delay medium of each of the transducers are bonded to the opposite surface of the coupling surface, and the transverse wave component ultrasonic signal input from each of the transducers to the backing material is converted into a longitudinal wave component ultrasonic wave. a multi-reflection type ultrasonic delay line comprising a backing material having a mode converting surface for converting an ultrasonic signal of a longitudinal wave component into an ultrasonic signal of a transverse wave component, and a backing material having a mode converting surface for converting an ultrasonic signal of a longitudinal wave component into an ultrasonic signal of a transverse wave component. A multi-reflection type ultrasonic delay line characterized in that a groove is provided in a direction perpendicular to the mode conversion surface and each side surface of the backing material is coated with a sound absorbing agent, and the groove is filled with a sound absorbing agent. .