JPH04323556A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To prevent an echo reflected at a flawed portion from interfering with a lens echo by connecting to a second sound wave transfer body a first sound wave transfer body having a concave lens face, and setting such a relation between the first and second sound wave transfer bodies that reflected transverse waves from a transmitting vibrator are not incident on a receiving vibrator. CONSTITUTION:A concave lens face 40A is formed at one end of a first sound wave transfer body 40 and an inclined face 40C having an angle theta2 with respect to an X axis perpendicular to the focusing axis of sound waves which is formed at the face 40A is formed at the other end. A second sound wave transfer body 41 is connected at one end to the inclined face 40C and a receiving vibrator 31 is provided on an inclined face 41A formed at an angle theta3 with respect to the X axis of the other end of the second sound wave transfer body. An inclined face 40B having an angle theta1 with respect to the focusing axis is formed in the side face of the transfer body 40 and is provided with a transmitting vibrator 30. Ultrasonic waves generated in the vibrator 30 by pulses transmitted from a pulser are reflected at boundary faces A, A' and are transmitted through the face 40A and transferred to a subject. Longitudinal waves reflected at the face 40A and the subject are refracted at the faces A, A' and received by the vibrator 31. Because of the angles theta1-theta3 and the positions of the vibrators 30,31 relative to each other the incidence of reflected transverse wave on the vibrator 31 is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual-element ultrasonic probe.

0002

2. Description of the Related Art The prior art will be explained with reference to FIGS. 3 and 4. FIG. 3 is a block diagram of a conventional probe 2 and a device for operating it, and FIG. 4 is a time chart of ultrasonic signals monitored by an oscilloscope. When a transmission pulse is applied to the transducer 3 by the pulser 1, an ultrasonic wave is excited in the transducer 3, the ultrasonic wave propagates through the sound wave propagation body 4, a part of which is reflected by the concave lens surface 4A, and the rest is reflected by the medium. 5 (5A
), and is focused and radiated to the subject 8. Also, the vibrator 3 has a lens echo L1 reflected by its concave lens surface 4A.
, the second reflected wave L2 of L1, the reflected echo S1 from the surface of the object, etc. are converted into electrical signals, and the electrical signals are amplified by the receiver 6 and then transmitted to the oscilloscope.
be monitored. The pulser 1 generates a transmission pulse and at the same time sends a trigger signal to the oscilloscope 7 to control the display.

[0003] Also, an X-cut crystal piezoelectric element or a ceramic piezoelectric element having the same properties is used as a vibrator, and its action is to vibrate in the thickness direction when a voltage is applied periodically in the thickness direction. Furthermore, it also vibrates in the lateral direction, although it is much smaller than the vibration in the thickness direction. The axial length of the sound wave propagation body 4 is L,
Assuming that the focal length is F0, the longitudinal and transverse sound velocities of the sound wave propagation body 4 are C1 and C2, respectively, and the longitudinal sound velocity of the medium 5 is C3, the lens echoes L1, L2 and the object surface reflection echo S1 shown in FIG. ), the propagation times from the transmission pulse T shown in ) are respectively T1, T2, and T3.

[Math. 1] T1=2×L/C1
(seconds)

[Math 2] T2=2×2×L/C1
(seconds)

[Math. 3] T3=2×(L/C
1+F0/C3) (seconds). Furthermore, since the vibrator vibrates in the transverse direction, the sound wave propagates in the sound wave propagation body 4 as a transverse wave, and the reflected echo S2 on the concave lens surface is received, and the propagation time T4 from the transmitted pulse is

[Math. 4] T4=2・(L/C2
+F0/C3) (seconds). In addition, in probe design, the relationship between these propagation times is as shown in Figure 4 (b).

[Math. 5] T1<T4<T3<T2 is often the case.

0004

[Problems to be solved by the invention] The problems of the prior art are as follows:
When the probe 2 is lowered by ΔZ and focused on the inside of the object 6, the reflected echo F inside the object 6 and the lens echo S2 interfere ( S
There is a range of ΔZ where 2+F) occurs, and within that range,
ΔZ
Due to minute displacements, the size of the interfering echoes changes and the phase of the ultrasonic waves shifts, making accurate evaluation impossible.

[0005] A particular problem that arises when the lens echo S2 and the defect reflection echo F interfere with each other will be described. Since minute defects inherent in ceramics etc. greatly affect the strength, it is necessary to detect minute defects. The signal intensity of the reflected echo from this minute defect is very low, and is often smaller than the lens echo S2. Therefore, in order to focus on this minute defect, ΔZ is slightly moved, but the signal strength changes due to interference between the lens echo S2 and the defect reflection echo F, making it difficult to focus accurately. . Furthermore, when the defect reflection echo F is digitized and subjected to waveform processing such as FFT (fast Fourier transform method), the lens echo S2
There was a problem that the influence of Also,
In order to reduce the lens echo S2, when manufacturing the transducer,
Although it is managed to vibrate as much as possible in the thickness direction, the vibration in the lateral direction does not go to zero.

An object of the present invention is to prevent the transverse wave component in which the transverse wave vibrates minutely in the transverse direction from the transverse wave component to prevent the transducer from receiving echoes reflected by the propagation of the transverse wave within the sound wave propagating body, thereby preventing defective reflected echoes from becoming lens echoes. An object of the present invention is to provide an ultrasonic probe that prevents interference.

[0007]

[Means for Solving the Problems] The probe of the present invention has a first
In an ultrasonic probe comprising a sound wave propagating body, a second sound wave propagating body, and a vibrator attached to each of them, a concave lens surface is formed at one end of the first sound wave propagating body, At the other end, an inclined surface is formed at an angle θ2 with respect to the X-axis perpendicular to the focusing axis (Z-axis direction) of the ultrasound formed by the concave lens surface, and one end of the second sound wave propagating body is formed on the inclined surface. is connected, and the other end thereof is formed with an inclined surface at an angle θ3 with respect to the X-axis, the one of the vibrators is mounted on the inclined surface, and the side surface of the first sound wave propagation body is provided with a surface facing toward the focusing axis. A sloped surface having an angle θ1 with respect to the focusing axis is formed, and the other vibrator is mounted on the sloped surface (Claim 1).

Furthermore, the probe of the present invention has angles θ1, θ2,
The relationship between θ3 and the positions of the two transducers is such that one of the transducers above emits ultrasonic waves and the transverse waves of the waves reflected from the sample do not enter the other transducer (
Claim 2).

[0009]

According to the present invention, reflected transverse waves generated from a transmitting transducer and returning to the other receiving transducer do not enter the receiving transducer (claims 1 and 2).

0010

[Embodiment] Fig. 1 is an embodiment of the present invention, Figs. 2 (a) and 2 (b) are detailed views of the configuration including the inclination angle, (a) is a sectional view, and (b) is a plan view. Fig. 5 is a time chart. The ultrasonic probe has two sound wave propagators 40 and 41 made of different materials and two vibrators 30 and 31.
has a cylindrical shape with a concave lens surface 40A. The upper part of this sound wave propagation body 40 has a sloped part, and the second sound wave propagation body 41 is used in contact with this slope part. A part of the side surface of the sound wave propagation body 40 has an inclined part from the top toward the inside, and the first vibrator 30 is installed on this inclined part. Further, a second vibrator 31 is installed on the sloped portion of the top of the second sound wave propagation body 41 .

The sound wave propagating bodies 40 and 41 are made of different materials; for example, when the sound wave propagating body 40 is made of sapphire, the sound wave propagating body 41 is made of quartz glass.

In the above embodiment, the inclinations of the three inclined parts and the positions of the transducers 30 and 31 are such that the reflected transverse waves generated from the transmitting transducer and returning to the other receiving transducer correspond to It is installed in such a way that it does not enter the receiving transducer, but details will be described later.

The operation will be explained. The pulser 1 generates a transmission pulse that excites ultrasonic waves in the transmission transducer 30, and sends it to the transmission transducer 30. As a result, ultrasonic waves (longitudinal waves) are transmitted to the sound wave propagation body 40 and reflected at the boundary surfaces A and A' with the other sound wave propagation body 41, and the concave lens surface 40A
The longitudinal waves reflected from the concave lens surface of the sound wave propagating body 40 and the longitudinal waves reflected from the subject 8 are transmitted through the sound wave propagating body 4 and propagated to the subject 8 .
1, is refracted at the interface A/A' with the receiving transducer 31, is amplified by the receiver 6, and is transmitted to the oscilloscope 7.
will be monitored.

The structure of the probe according to the present invention will be explained in detail with reference to FIG. Before that, as shown in Fig. 6, when the ultrasonic wave is obliquely incident on the interface between individuals D and E, the longitudinal wave velocity and shear wave velocity and density of individuals D and E are C5, C6, ρ1.
, C7, C8, and ρ2, the following equation is obtained according to Snell's law.

[Formula 6] C5/Sinθi=C5/Sinθ5=C6/
Sinθ6=C7/Sinθ7=C8/Sinθ8where, θi is the angle of incidence of longitudinal waves on individual D from the normal to the boundary surface,
θ5 is the longitudinal wave reflection angle at individual D from the normal to the boundary surface, θ
6 is the transverse wave reflection angle at individual D from the normal to the boundary surface, θ7
is the longitudinal wave refraction angle from the normal line of the boundary surface to the individual E, and θ8 is the transverse wave refraction angle from the normal line of the boundary surface to the individual E.

[0015] In this embodiment, such a relationship is actively utilized. That is, in FIG. 2, the dashed-dotted line 0-l of the first sound wave propagating body 40 indicates the focusing axis along which the ultrasonic waves are focused by the concave lens surface 40, and is shown as the Z-axis in the vertical direction on the paper, and is perpendicular to this. When the left and right direction on the paper is the X axis, and the direction perpendicular to the paper that is perpendicular to Z and An inclined surface 40B having an angle θ1 with respect to the Z-axis is cut out from a part of the side surface thereof from the top toward the inside. The vibrator 30 is installed on this inclined surface 40B. The vibrator 30 includes, for example, a piezoelectric element and an electrode. On the other hand, the top of the sound wave propagation body 40 is at an angle θ2 with respect to the X axis.
An inclined surface 40C is formed. The bottom surface of the sound wave propagation body 41 is formed into an inclined surface at the angle θ2 so as to match the inclined surface 40C. These two inclined surfaces are bonded together via a thin film of a medium such as silicone oil, and have the effect of reflecting and refracting ultrasonic waves. The upper surface of the sound wave propagating body 41 is an inclined surface 41A cut out from the top at an angle θ3 with respect to the X-axis as shown in the figure. A second vibrator 31 is placed on this inclined surface.
Set it up.

With this configuration, it is assumed that the vibrator 30 is used as a transmitting vibrator. Let us describe the relationship between θ1, θ2, and θ3. Now, assuming that one point O on the boundary surface is the incident and reflection point, the incident angle θi from the vibrator 30 to this point O and the reflection angle θr to the concave lens surface 40A are as shown in FIG. In addition, the ultrasonic waves reflected and propagated by θr are transmitted to the concave lens surface 40.
The angle θt at which the ultrasonic wave reflected by A and the object 8 and returned is refracted at point O is also as shown in FIG. Here, the ultrasonic sound axes are to, ol, and or, respectively. The normal is HH
' is indicated.

[0017] The longitudinal sound velocity between to, ol, or is Cot,
If Col and Cor are used, the following formula holds true from Snell's law.

[Formula 7] Cot/Sinθi=Col/Sinθr=C
or/SinθtHere, when the sound wave propagation body 40 is acoustically isotropic, Cot=Col, so θi
= θr, and θt is

[Equation 8] It is expressed as θt=Sin-1 (Cor/Col), and θ1, θ2, and θ3 can be determined by the following formula.

[Formula 9] θ1=π/2-(θi+θ2)=π/2-2θ
i

[Formula 10] θ2=θi

[Formula 11] θ3=θt

On the other hand, when the sound wave propagation body 40 is acoustically anisotropic, θ1, θ2, and θ3 are as follows.

[Formula 12] θ1=π/2−(θi+θ2)

[Formula 13] θ
2=θr=Sin-1(Cor/Cot)

[Formula 14] θ
3=θt=Sin-1 (Cor/Col).

Next, the determination of θi will be explained. Assuming that there is no anisotropy in the sound wave propagating body, the sound pressure reflectance T1 incident from the transmitting vibrator 30 side and reflected to the concave lens surface, and the concave lens surface The design is made so that the product of the sound pressure passing rate R1 which enters the receiving transducer 31 from
T1 and R1 are expressed as functions of longitudinal and transverse wave velocities, densities, and θi of the first and second sound wave propagators, respectively).

According to the above configuration, the transverse waves generated from the transmitting vibrator 30, which was a problem in the conventional method, can be avoided at the boundary surface A.
At A', the reflection angle is different from the reflection angle of the longitudinal wave according to Snell's law. Furthermore, since the receiving transducer 31 is set at a position where it does not receive this reflected wave, it is shown in (d) in FIG. 5 when the distance is long, and (e in FIG. 5) when the distance is short.
), and there is no reception of reflected transverse waves in either case. As a result, even if the probe is brought close to the object to be examined in order to focus on the defect inherent in the object, the result will be as shown in (e) of Fig. 5, and the signal S2 will not be generated, and no interference with the signal F will occur. .

Although this embodiment has been explained using a point focus type probe, it is obvious that the present invention can be applied to a line focus type probe (cylindrical type) shown in FIG. It goes without saying that the symbols defined by the hyphen in FIG. 7 correspond to the symbols in FIG. 2, respectively.

[0022]

[Effects of the Invention] According to the present invention, since there is no reception of reflected waves of transverse waves, there is no interference with normal reflected signals even when the probe approaches a defective part of the sample, and only accurate reflected signals can be received. Detection becomes possible. Therefore, when evaluating the V(Z) curve, there is no distortion of the V(Z) curve due to interference, and accurate evaluation can be performed.

[Brief explanation of drawings]

FIG. 1 is an embodiment diagram of an ultrasonic probe of the present invention.

FIG. 2 is an embodiment diagram of an ultrasonic probe main body of the present invention.

FIG. 3 is an example diagram of a conventional ultrasonic probe.

FIG. 4 is a conventional time chart.

FIG. 5 is a time chart of this embodiment.

FIG. 6 is an explanatory diagram of incident waves and reflected waves in different media.

FIG. 7 is a diagram showing an embodiment of the present invention for a line focus type probe.

[Explanation of symbols]

1 Parsa 6 Receiver 7 Oscilloscope 20 Probe 30 Transmitting transducer 31 Receiving transducer 40 First sound wave propagator 41 Second sound wave propagator

Claims (2)

[Claims] Claim 1: An ultrasonic probe comprising a first sound wave propagating body, a second sound wave propagating body, and a transducer attached to each of them, wherein one end of the first sound wave propagating body forms a concave lens surface, and at the other end is formed an inclined surface at an angle θ2 with respect to the One end of the second sound wave propagating body is connected, the other end is formed with an inclined surface at an angle θ3 with respect to the X axis, the one vibrator is mounted on the inclined surface, and the side surface of the first sound wave propagating body is connected. An ultrasonic probe characterized in that an inclined surface is formed at an angle θ1 toward the focusing axis, and the other transducer is mounted on the inclined surface. 2. In the ultrasonic probe according to claim 1, the relationship between the angles θ1, θ2, θ3 and the positions of the two oscillators is such that the relationship between the angles θ1, θ2, θ3 and the positions of the two oscillators is such that when one of the oscillators transmits an ultrasonic wave and the ultrasound is reflected from the sample, An ultrasonic probe in which the transverse waves of the waves do not enter the other transducer.