JP2673289B2 - Ultrasonic device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic wave that emits an ultrasonic beam toward a subject and obtains acoustic information about the state of the surface of the subject and the vicinity thereof. Regarding the device. (Prior Art) Conventionally, an ultrasonic device for generating ultrasonic waves to observe the surface and the inside of an object has been disclosed, for example, in JP-A-58-22978. FIG. 2 shows such an ultrasonic device. That is, the arc-shaped transducers T _in and T _out are arranged on one plane of the voltage plate 1 in such a manner that one circle is divided into two. The transducers T _in and T _out each have a pair of interdigitated interdigital electrodes 2a, 2b; 3a, 3b. Transducer T
_in functions as an electrode that transmits an ultrasonic beam. The transducer T _out functions as an electrode that receives the reflected wave of the ultrasonic beam. The piezoelectric plate 1 has a third structure in order to function as an ultrasonic device.
As shown in the drawing, the surface provided with the transducer T _in is placed so as to be immersed in the liquid L (for example, pure water). Further, the subject 4 is placed at a position in the liquid that opposes the piezoelectric plate 1. An electric signal S _i in the radio frequency range, which is determined by the piezoelectric plate 1 and the electrode period, is applied to the interdigital electrodes of the transducer T _in from a signal source (not shown). As a result, as shown by the arrow in FIG.
Angle theta ₁ which the T _in are toward the subject 4, θ ₂ (0 <
With θ ₁ <90 °, 0 <θ ₂ <90 °, a longitudinal ultrasonic wave beam in the liquid L is emitted. This ultrasonic beam is the liquid L
The light propagates through the inside and reaches the subject 4, a part of which is reflected by the surface of the subject 4 (dotted line), and the other proceeds inside and is reflected (solid line). The reflected longitudinal acoustic wave is again incident on the transducer T _out via the liquid L and is converted into an electric signal S _o . As long as the reflection point and its vicinity are not elastically anisotropic, the transducers T _in and T _out have a confocal point on the central axis of the circle, so they are detected by the transducer T _out ,
It is taken out as an electric signal S _o . Electrical signal S _o is electrical signal
This is a signal obtained by delaying S _i , and if elastic anisotropy exists on the surface of the subject 4 irradiated by the ultrasonic beam or inside thereof, the propagation velocity of the sound wave changes, and the amplitude changes correspondingly. Or, the phase difference changes. Therefore, it is possible to detect a crack on the surface of the object and its vicinity by performing signal analysis on the electric signal S _o having this amplitude and phase difference. (Problems to be Solved by the Invention) However, according to the conventional ultrasonic apparatus having such a configuration, since there is only one transducer that receives the ultrasonic wave beam, the ultrasonic beam of such a transducer causes the object to be detected. However, there is a problem that only a single amplitude information and a single phase information can be obtained from a single receiving transducer even when scanning. The present invention has been made for the purpose of solving the problems that the above-mentioned conventional techniques have.
An object of the present invention is to provide an ultrasonic device that can obtain sufficient information about an object of a subject. (Means for Solving the Problems) An ultrasonic device of the present invention has a transducer for transmission and a transducer for reception which are respectively disposed on a piezoelectric plate, and an ultrasonic beam of the transducer for transmission is applied to a subject. The ultrasonic beam reflected by the subject is received by the receiving transducer to obtain acoustic information about the subject. The transmitting transducer and the receiving transducer are , An arc-shaped interdigital transducer forming concentric circles on the same plane of the same piezoelectric substrate, a transmission transducer is a single transducer, and a reception transducer is acoustically independent and is divided into two. It is divided and arranged in directions orthogonal to each other so as to obtain detection outputs of ultrasonic beams orthogonal to each other. ing. (Operation) Since the transmitting transducer and the receiving transducer are arc-shaped interdigital transducers that form a concentric circle on the same plane of the same piezoelectric substrate and the transmitting transducer is a single transducer,
When the detection output of the ultrasonic beams orthogonal to each other is obtained from the receiving transducer, the manufacturing process becomes very easy. That is, an ultrasonic device capable of reliably detecting orthogonal ultrasonic beams can be easily and accurately manufactured only by acoustically independently dividing the receiving transducer into two and arranging them in directions orthogonal to each other. is there. In the interdigital transducer, the overlapping portion of the interdigital transducer effectively functions as a transducer for emitting and receiving the ultrasonic beam, and the emitting and receiving directions of the ultrasonic beam are perpendicular to the interdigital electrode. . Therefore, the receiving transducer is divided into two by forming concentric circular arcs on the same plane of the same piezoelectric substrate and forming the angle of the interdigital transducer fingers of each transducer so that the receiving directions are orthogonal. It can be manufactured. Moreover, according to the present invention, by detecting two orthogonal ultrasonic beams in this way, good azimuth resolution can be obtained in each orthogonal direction, so that the resolution (distance resolution) in the traveling direction of the ultrasonic beam can be improved. It can be greatly improved. (Embodiment) FIG. 1 is a plan view showing an embodiment of the present invention. An arc-shaped transducer is provided on one plane of the piezoelectric plate 1.
T _in , T _out1 , and T _out2 are arranged in the form of dividing one circle into three. Transducer T _in , T _out1 and T
_out2 is the opening angle α, β and β (where α> 2)
β) and three sets of interdigitally arranged interdigital electrodes 5
a, 5b; 6a; 6b; 7a, 7b. The transducer Tin functions as a transmission electrode and is driven by the electric signal S _i . The transducers T _out1 and T _out2 are acoustically independent and function as receiving electrodes,
Outputs electrical signals S _O1 and S _O2 . Next, the operation of such a configuration will be described with reference to FIG. In the illustrated state, the piezoelectric plate 1 is a transducer
It is assumed that the surface provided with T _in , T _out1 and T _out2 faces downward and is immersed in the liquid L (for example, pure water). Further, at the position in the liquid L facing the piezoelectric plate 1, the subject 4
Is arranged. The interdigital transducer electrodes 5a and 5b of the transducer T _in are determined by the piezoelectric plate 1 and the electrode period, and the radio frequency, for example, 10
An electric signal S _i in the frequency range of 0 MHz or less is applied from a signal source (not shown). This allows the transducer T _in
To the subject 4, that is, the angle θ shown in the figure.
A longitudinal ultrasonic wave beam is emitted into the liquid L due to (0 <θ <90 °). This ultrasonic beam propagates through the liquid L and reaches the subject 4, a part of which is reflected by the surface of the subject 4 and the other part of which propagates inside and is reflected. Each of the reflected longitudinal acoustic wave beams is transmitted through the liquid L again to the transducer.
It is incident on T _out1 and T _out2 and converted into electrical signals S _O1 and S _O2 containing phase information orthogonal to each other. Here, as long as there is no elastic anisotropy at or near the reflection point of the ultrasonic beam, the transducers T _in , T _out1 and
Since T _out2 has a confocal point on the center axis of the circle, electric signals S _O1 and S _O2 having almost the same delay time are taken out from the transducers T _out1 and T _out2 . However, if elastic anisotropy exists at the reflection point and its vicinity, the ultrasonic beam reflected by the surface of the subject 4 and
The difference in the propagation time between the longitudinal acoustic wave beam that travels inward and is reflected becomes large. Correspondingly, the electrical signals S _O1 and S _O2 also differ greatly from each other. Electrical signal S _O1 and S _O2 is because it has such properties, for example, the surface of the object 4 is scanned by the ultrasonic beam of the transducer T _in, the transducer T _out1 and T
_The electrical signals S _O1 and S _O2 received by _out2 are gated by a gate circuit, respectively, and held for a predetermined time by a sample and hold circuit to perform signal analysis on the amplitude of both and the phase difference between the two. It is possible to detect information related to the object 4, such as scratches inside the subject 4, or to create a stereoscopic image showing the shape of the surface. When a leaky Rayleigh wave is used as the ultrasonic beam, the thickness of the piezoelectric plate 1 is configured to be thicker than the electrode cycle length, and the piezoelectric plate 1 is arranged so that the surface having the electrodes is in contact with the liquid L. To place. However, when the leaky Lamb wave is used, the piezoelectric plate 1 may be arranged so that the plate thickness is smaller than the periodic length thereof and the surface opposite to the electrode surface contacts the liquid L. (Effect of the invention) As described in detail above, according to the present invention, the transducer for transmission and the transducer for reception are arc-shaped interdigital transducers forming concentric circles on the same plane of the same piezoelectric substrate, The transducer for transmission is a single transducer, and the transducer for reception is acoustically independent and is divided into two, and the directions are orthogonal to each other so as to obtain detection outputs of ultrasonic beams orthogonal to each other. Since it is arranged in the above, it is possible to easily and accurately manufacture an ultrasonic device capable of surely detecting orthogonal ultrasonic beams. Moreover, the resolution (distance resolution) of the subject in the traveling direction of the ultrasonic beam can be significantly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an ultrasonic apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of a conventional ultrasonic apparatus, and FIGS. 3 and 4 are ultrasonic apparatus. It is a path diagram of an ultrasonic beam. 1 ... Piezoelectric plate, T _in , T _out1 , T _out1 …… Transducer.

Claims (1)

(57) [Claims] Having a transducer for transmission and a transducer for reception which are respectively arranged on a piezoelectric plate, radiates an ultrasonic beam of the transducer for transmission to a subject, and receives the ultrasonic beam reflected from the subject. In an ultrasonic device configured to receive acoustic information about the subject by receiving with a transducer for transmission, the transducer for transmission and the transducer for reception form concentric circles on the same plane of the same piezoelectric substrate. Is a circular arc-shaped interdigital transducer, the transmitting transducer is a single transducer, and the receiving transducer is an acoustically independent two-divided ultrasonic wave which is orthogonal to each other. Characterized in that they are arranged in directions orthogonal to each other so as to obtain the detection output of the beam. Ultrasonic device.