JPH01810A - ultrasonic delay line - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic delay line, and particularly to a compact ultrasonic delay line that increases the amount of attenuation of unnecessary signals.

[Prior Art] A conventional 1 + - (small return bus-shaped multiple reflection type ultrasonic delay line is shown in FIG. It is a pentagon with an axis of symmetry with two corners cut out, and a piezoelectric body I for input/output transducer is attached to the hypotenuse ΔB of the notch.The center of the piezoelectric body I is the center of the hypotenuse AI3. A sound absorbing material 3 is coated on the main surface of the ultrasonic delay medium 2, and the shape and area of the sound absorbing material 3 are such that at the center of the main surface, e , f
It is a flower pattern consisting of four triangles each having the same area as shown in the figure, and on the periphery of the main surface, there are triangles a, d, b and C, each having the same area, and squares g and h, each having the same area. The coating shape i is rectangular and only one is provided.

Furthermore, as shown in FIG. 8, the planar shape of the main surface of the ultrasonic delay medium 9 is a rectangle in which one corner of one short side of the rectangle is obliquely cut out, and the hypotenuse KL of the cutout is A reflective ultrasonic delay line in the form of a return bus to which a piezoelectric body 11 for input/output transducers is attached is also known. In this case, the center of the piezoelectric body 11 is attached so as to coincide with the length of the oblique side KL from K to the station. Ultrasonic delay medium 9
A sound absorbing material (0) is applied to the main surface of the sound absorbing material 1.
The application shape and application area of 0 are squares with the same area at the center of the main surface, triangles with the same area at the periphery of the main surface, and L, M, N and hypotenuses at the corners. They are each applied near the center of the tree so that they penetrate somewhat into the main signal path. In the return bus-shaped ultrasonic delay line, the ultrasonic waves generated from the input transducer are multiplexed within the ultrasonic delay medium with the anti-Q-1L and anti-q- planes (side BC in Figure 6 and side BC in Figure 8). is reflected from the center of the KL side (the part of the length KL), follows almost the same path, and is output from the output transducer.

[Problems to be Solved by the Invention] Conventionally, small ultrasonic delay lines have had a major problem in that the output level of unnecessary signals is large.

[Means for Solving the Problem] The present invention has been made to extremely reduce the output level of unnecessary signals of a small ultrasonic delay line, and the planar shape of the main surface of the ultrasonic delay medium is such that the long side The ratio of the short side and the short side is approximately 2N+
l : 2 (N is an integer of 2 or more) A pentagon with a symmetry axis obtained by diagonally cutting out two corners at both ends of one short side of a rectangle, and one of the notches is used for input/output transducers. The piezoelectric body is attached, or the planar shape of the main surface is a rectangle with a long side to short side ratio of approximately N:1, and the corner of one short side of the rectangle is cut out diagonally, and the cutout part In a return bus-shaped multi-reflection ultrasonic delay line with a piezoelectric body for input/output transducers, the area other than the main signal path determined by the width of the piezoelectric body is located at the center of the main surface of the ultrasonic delay medium. The present invention provides an ultrasonic delay line which is rectangular in shape and is characterized in that sound absorbing materials are arranged in parts other than the main signal path so as to partially intrude into the main signal path.

[Function] In the present invention, the piezoelectric body for the crowd transducer is mounted by shifting the position from the center of the mounting surface, or by mounting the piezoelectric body by moving the entire surface in the direction of the long side of the ultrasonic delay medium. It is no longer necessary to move the ultrasonic delay medium in parallel to slightly lengthen or shorten it in the long side direction so that the center of the piezoelectric body matches the center of the mounting surface. This is considered to be effective in avoiding the 0.5°C spurious path, which is the highest level among the signals.

Further, it is also effective to expand the shape of the sound-absorbing material applied to the central part and part of the peripheral part of the ultrasonic delay medium only in one direction, which effectively absorbs the signal passing through the spurious path with a value of 0.5.

Both FIG. 3 and FIG. 4 show developed views of an ultrasonic delay line according to an embodiment of the present invention. The piezoelectric body is shifted in a direction that reduces the area of the shaded part in FIG.

When the piezoelectric body is not shifted, the portion other than the main signal path has a square shape at the center near the axis of symmetry of the main surface, but when the piezoelectric body is shifted, it becomes a rectangle.

In addition, when mounting the piezoelectric body, the surface and the reflecting surface are moved parallel to the long side direction of the ultrasonic delay medium, and the center of the piezoelectric body is aligned with the center of the surface. Compared to the case where the piezoelectric body is shifted, if the length of the parallel movement is appropriately selected, the 0°5-C spurious path and the main signal path will be slightly shifted, but the shape of the area other than the main signal path will be slightly different. Since the areas are equal at the center of the main surface of the ultrasonic delay medium,
It is recognized that if the sound absorbing material is applied in a similar manner, it will be effective in attenuating unnecessary signals.

The shaded area in FIG. 3 indicates an area where 0.5 of the main signal path is covered by the spurious path, and the smaller the area, the more effective it is for spurious attenuation. Also,
The shaded area in FIG. 4 indicates a spurious path with a value of 0.5, and it is considered that a coating pattern of the sound absorbing material that absorbs the signal passing through the shaded area is effective in reducing spuriousness with a value of 0.5.

[Example] FIG. 1 shows a diagram of an example of the present invention. Ultrasonic delay medium
The planar shape of the main surface of is such that the ratio of long side to short side is approximately 2N+I
:2 (N is an integer of 2 or more) The two corners at both ends of one short side of a rectangle are cut out to form a pentagon having an axis of symmetry. The piezoelectric body 2 for the input/output transducer is attached to the oblique side AB, which is the part, and the center of the piezoelectric body 2 does not coincide with the center of the oblique side AB, and is shifted by an amount be. A sound absorbing material 3 is coated on the main surface of the ultrasonic delay medium 1, and in the center of the main surface, the sound absorbing material has a rectangular application pattern c, f, and the first reflection q= In the vicinity of the area, a triangular application pattern d has a larger area than other similar patterns.

The triangular coating patterns a, b, and c and the square coating patterns g, h, and i are coated in areas other than the main signal path so as to extend somewhat into the 1414 path.

The main signal path is equal to the width of the IJ'' electric body of the input transdecoder. In this example, the dimensions of the ultrasonic delay medium are 25.09 mm long side AE, 25.09 mm CD;
is 12.52mm, hypotenuse A11.13G is 8.58m
m, the angle between hypotenuse AB and ΔE is 135°. The m point 13 is cut by 0.2n+n+. The total length of the piezoelectric body 2 is 8 mm, and the length of each piezoelectric body of the input/output transducer is 3.8 mm, and they are attached to the oblique side B with an interval of 0.4 mm. As shown in the enlarged plan view of the oblique side AB in FIG. 1(a), the center of the piezoelectric body 2 is mounted offset from the center of the oblique side An by 0.2 mmB. It is considered that the most appropriate distance for shifting is 0.02 to 0.04 times the hypotenuse AB. The length ratio between the short side ED and the long side AE, Ci1 is l:2. In the above configuration, if the center of the piezoelectric body 2 is mounted without shifting from the center of the oblique side AB, the area surrounded by the main signal path will be in a regular square shape at the center of the main surface, but the piezoelectric The center of body 2 is the hypotenuse AB
If you install it offset from the center, it will become a rectangle. In the rectangular application patterns e and f, the entire circumference of the rectangular area other than the main signal path is lengthened by a certain distance so as to fit into the main signal path, and furthermore, by 0.5, the entire circumference of the rectangular area other than the main signal path is lengthened so as to fit into the spurious path. Stretch the long side and apply. FIG. 5 is an enlarged plan view showing the coating shapes of rectangular coating patterns e and f. The shape of the area 7 other than the main signal path before shifting the piezoelectric body is a square at the center of the main surface, and the length of the negative side is β. After the piezoelectric body is shifted by X, the area 8 other than the main signal path becomes a rectangle, the long side of which becomes β÷2x, and the X′7 side becomes β−2x. Further, the entire circumference of the rectangle is lengthened so that the main signals Δ, In the coating shape, the ratio of the short side to the long side is expressed by: β is determined by the shape and size of the ultrasonic delay medium and piezoelectric body, and X' and a can be adjusted arbitrarily, but they can also be set to a constant value by selecting the optimum value. If the values of a and x' are fixed, the ratio depends only on X, and in the present invention, it is 0.80 to
It is 085. In fact, in the embodiment shown in FIG. 1, the long side is 3.0 mm and the short side is 2.4 mm, so the ratio of the short side to the long side is 0.8.

The triangular coating pattern d has a larger area than the other triangular coating patterns aJ and c.
Horn? The four sides have the same length as the long sides of the rectangular coating patterns e and f. The triangular coating pattern d is applied to a triangular region other than the main signal path near the first inverse q= of the main signal so as to extend somewhat into the main signal path. The shape and area of the triangular coating pattern d are not particularly limited, and the coating may be applied so as to fit into the main signal path somewhat. Also, in this example, the ratio of the short side ED to the long sides AE and CD of the ultrasonic delay medium is l:2, but I:n
(n is an integer of 2 or more). However, in a multi-reflection type ultrasonic delay line with a return path shape having a reflection surface 11G as in the present invention, the long side AE,
As the CD becomes longer, the number of reflections of the main signal increases, so the amount of attenuation of the main signal and the level of unnecessary signals increase. Therefore, it is effective to set the ratio of the short side ED to the long sides AE and CD to be 1:2, so that the length of the long side is the shortest.

FIG. 2 is a plan view of an ultrasonic delay line showing another embodiment. The dotted line part is the short side Jl and the long side 1., 1.
II The mounting of the piezoelectric body when the length ratio of l is 1:2 shows a surface and a reflective surface.

If the center of the piezoelectric body 2 is mounted so as to coincide with the center of the FG, it will be the same as if the piezoelectric body was mounted offset in six directions at the dotted line portion. Therefore, when mounting the piezoelectric body, even if the surface and the reflecting surface are made to protrude in parallel to the long side direction of the ultrasonic delay medium, if the length of the protrusion is appropriately selected, the difference will be 0. 5, the spurious path and the main signal path are shifted, but the shape and area of the area other than the main signal path are the same at the center of the main surface of the ultrasonic delay medium, so if the sound absorbing material is applied in the same shape, unnecessary signals can be It is effective in attenuating the

The shape of the ultrasonic delay medium 6 is such that the piezoelectric body 2 of the ultrasonic delay medium of the embodiment shown in FIG. . The input/output transducer piezoelectric body 2 is mounted on the surface FG so that the center of the piezoelectric body 2 and the center of the surface FG are aligned. The application pattern and application position of the sound absorbing material 3 are as follows:
j.

k, 1. m, n, o, p, q, r are coating patterns a, b, c, d, e, f shown in the example of FIG.
, g, h, and i, and the application positions are also the same.

The length ratio between the short side Jl and the long sides FJ, II+ is such that the long side is slightly larger than twice the short side. In addition, in this case, the mounting of the piezoelectric body 2 involves moving the surface FG and the reflecting surface GH in parallel in the direction of the long side of the ultrasonic delay medium so that the long side becomes shorter, compared to the embodiment shown in FIG. The length ratio between the short side and the long side is such that the long side is slightly smaller than twice the short side.

Furthermore, another embodiment is shown in FIG.

The planar shape of the main surface of the ultrasonic delay medium is a rectangle with a long side to short side ratio of approximately N:1 (N is an integer of 2 or more), with one corner of one short side of the rectangle cut out. . The piezoelectric body 11 for the input/output transducer is attached to the hypotenuse KL, and the center of the piezoelectric body 11 is shifted by X toward the L side from the part K of the hypotenuse KL. The ratio of the long side M to the short side MN is 4:1, and the application pattern of the sound absorbing material 10 is the same as that shown in FIG. It is coated so that it penetrates to some extent. The angle between side KL and side LM is 4
5", and the apex is cut 0.2 mm to prevent nicks. The center of the piezoelectric body 11 is 0.2 mm from the K to 'A K L fi part of the hypotenuse KL to the L side. 2mm
It is installed offset. The shifting distance is the hypotenuse K
It is preferably 0.02 to 0.04 times as much as L. The application pattern of the sound absorbing material 10 at the center of the main surface is a rectangle in which the short side is 0.8 times the long side, similar to the embodiment shown in FIG. Also in this embodiment, the shape of the ultrasonic delay medium 9 is adjusted so that the oblique side KL is moved in parallel in the long side direction as in FIG. 2, and the piezoelectric body l! can also be mounted in conventional locations.

[Effects of the Invention] The present invention provides an arrangement in which the center of the piezoelectric body for an input/output transducer is shifted from the center of the surface of the ultrasonic delay medium, and the piezoelectric body is mounted at the shifted distance. In relation to this, by adjusting the applied shape and area of the sound-absorbing material, in the above example, the spurious (also excluding 2τ and 3) showed an I OdB attenuation of +7L from -25 dB to -35 dB, It shows the excellent effect of reducing the signal level to 1/3 of the conventional level.Also, 0.5, which is unique to the return bus shape, is most effective in attenuating spurious. The mounting of the body can be done by moving the surface and the reflecting surface parallel to the long side direction of the ultrasonic delay medium.
It is recognized that it has a similar effect. Furthermore, when a large number of unnecessary signals are generated, such as from a small ultrasonic delay line, and the level is too high, by adopting the configuration of the present invention, a super I do not accept that it is possible to obtain a delay line.

[Brief explanation of the drawing]

1 and 7 show an embodiment of the present invention,
FIG. 1(a) is a partial enlarged view of the piezoelectric body mounting position, FIG. 1(b) and FIG. 7 are plan views of the ultrasonic delay line according to the present invention, and FIG. 2 is another implementation. In the plan view showing the example, the third
Figures 6 and 4 are developed views of the ultrasonic delay line in Figure 1, Figure 5 is an enlarged view of the rectangular coating pattern, and Figures 6 and 8 are T-plane views of conventional ultrasonic delay media. l...Ultrasonic delay medium, 2...Piezoelectric body, 3...Suction material, 4.
...Rectangular coating pattern, 5...Triangular coating pattern

Claims (1)

[Claims] The planar shape of the main surface of the ultrasonic delay medium is a rectangle with a long side to short side ratio of approximately 2N+1:2 (N is an integer of 2 or more). It is a pentagon with an axis of symmetry with diagonal notches cut out, and a piezoelectric material for an input/output transducer is attached to one of the notches, or the planar shape of the main surface is such that the ratio of the long side to the short side is approximately the same. A multi-reflection type ultrasonic delay in the form of a return bus, which is a rectangle in which one corner of one short side of the N:1 rectangle is diagonally cut out, and a piezoelectric material for input/output transducers is attached to the cutout. In the line, the area other than the main signal path determined by the width of the piezoelectric material is
The central part of the main surface of the ultrasonic delay medium is rectangular,
An ultrasonic delay line characterized in that a sound absorbing material is arranged in a portion other than the main signal path so as to partially intrude into the main signal path.