JPS6344194B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasound probe and a method of manufacturing the same, particularly an ultrasound probe that is used in an ultrasound diagnostic device to transmit and receive diagnostic ultrasound toward a subject, and a method of manufacturing the same. Regarding improvements.

2. Description of the Related Art Currently, in the field of medicine and the like, ultrasonic diagnostic apparatuses are used that display images of the inside of a living body using ultrasonic waves. In this device, the ultrasonic probe used to transmit and receive ultrasonic waves toward a subject such as a living body has a wide field of view and can be used within the entire field of view in order to reliably diagnose diseased tissues. It is required to have high resolution.

However, while conventional probes have a fixed focus, have high resolution near the focus, and can obtain clear images,
The drawback was that a sufficiently clear image could not be obtained at long distances. For this reason, research has been carried out on ultrasonic probes that can obtain clear images with high resolution regardless of distance, from short to long distances. A ring-shaped ultrasonic probe is known as a result of such research. This ring-shaped probe has the sharpest directivity from the immediate vicinity to the farthest distance. However, this probe has a large first sub-maximum of -16 dB, which indicates unnecessary sensitivity in directions other than the target direction, and the on-axis sensitivity, which indicates sensitivity at far distances, rapidly decreases in inverse proportion to the square of the distance. It has two drawbacks. In order to eliminate these shortcomings,
A virtual ring-shaped ultrasonic probe shown in FIG. 1 was developed. This probe has a structure in which a flat ultrasonic transducer 12 is laminated on an acoustic backing material 10, and an acoustic lens 14 is further laminated on this vibrator 12. , as shown in FIG. 2, is formed in the shape of a rotating surface in which two circular arcs with centers 0 and 0' are rotated about the central axis X--X'. This acoustic lens 14 applies virtual ring focus to the ultrasonic waves transmitted and received from the transducer 12, and arranges the apparent sound source of the ultrasonic waves behind the transducer in a ring shape with a diameter of 00' (hereinafter referred to as This apparent ring-shaped sound source is referred to as a virtual ring sound source). In this way, by placing the apparent sound source behind the transducer 12, the decrease in the axial sensitivity of the probe is compensated, and this apparent sound source forms a wide ring sound source with a diameter of 00'. As a result, the sub-maximum is sufficiently suppressed. However, since this virtual ring-shaped probe needs to be used by stacking acoustic lenses 14 of different thicknesses on the vibration surface of the flat transducer 12, multiple reflections of ultrasonic waves occur within this acoustic lens 14. As a result, the pulse width of the received echo becomes substantially longer, resulting in a disadvantage that the distance resolution of the ultrasonic diagnostic image deteriorates.

The present invention was made in view of these conventional problems, and its purpose is to sufficiently suppress sub-maximum while
An object of the present invention is to provide an ultrasonic probe that has sharp directivity from short distances to long distances and does not cause deterioration in distance resolution of ultrasonic diagnostic images.

In order to achieve the above object, the present invention provides an ultrasonic probe that transmits and receives ultrasonic waves toward a subject from an ultrasonic transducer laminated on an acoustic backing material.
The vibration surface of the ultrasonic vibrator is formed in the shape of a rotating surface of two circular arcs, and the virtual ring sound source of the ultrasonic wave is arranged behind the vibrator.

Further, in the above ultrasonic probe, a polymer piezoelectric film is generally used as the ultrasonic transducer. Here, since the polymer piezoelectric film loses its polarization when heated, there is a problem with its manufacturing method.

Therefore, in order to solve the above problems, the method of the present invention is such that a piezoelectric polymer film is thermally compression molded so that the vibration surface has a rotating surface shape of two circular arcs, and an ultrasonic virtual ring sound source is arranged behind it. An ultrasonic transducer is manufactured by forming an ultrasonic transducer, then performing a polarization operation on this ultrasonic transducer, and laminating the ultrasonic transducer on a pre-formed acoustic backing material. It is characterized by

Next, preferred embodiments of the present invention will be described based on the drawings. Note that the same reference numerals are given to the parts corresponding to each of the above-mentioned members, and the explanation thereof will be omitted.

In view of the fact that the drawback of the conventional probe shown in FIG. 1 is caused by the use of an acoustic lens, the ultrasonic probe of the present invention has a vibration surface of the ultrasonic transducer itself that is a two-arc rotation surface. By forming a virtual ring sound source behind the transducer without using an acoustic lens, the distance resolution of the ultrasonic diagnostic image obtained through this probe is improved.

FIG. 3 is an explanatory view showing the cross-sectional structure of such an ultrasonic probe, which is formed by sequentially laminating an ultrasonic transducer 12 and an acoustic matching layer 16 on an acoustic backing material 10. The surface shape of each of these members, that is, the acoustic backing material 10, the vibrator 12, and the matching layer 16, is composed of a rotating surface rotated about the central axis X-X' of two circular arcs,
The two circular arcs used as a reference for this rotating surface have a shape in which the center does not intersect with the central axis X--X'. In this embodiment, the acoustic backing material 10 is made of silicone rubber containing tungsten powder, the vibrator 12 is made of a polymer piezoelectric film, and the acoustic matching layer 16 is made of polyester. The above polymer piezoelectric film is, for example, a piezoelectric film obtained by polarizing polyvinylidene fluoride, polyvinyl fluoride, copolymers containing these as main components, or a mixture of these and ferroelectric ceramic powder. means the body.

The present invention has the above configuration, and its operation will be explained next.

In the ultrasonic probe of the present invention, the vibration surface of the vibrator 12 is formed as a rotating surface of two circular arcs, so unlike the conventional probe shown in FIG. 1, there is no need to use an acoustic lens. Virtual ring focus can be performed by placing a virtual ring sound source behind the vibrator 12. Therefore, when performing ultrasonic diagnosis by bringing the acoustic matching layer 16 of the probe into contact with a subject such as a living body, the transmission and reception of ultrasonic waves directed from the transducer 12 toward the subject are multiplexed within the acoustic lens. This can be done without causing reflections, and as a result, the ultrasonic diagnostic image of the subject obtained through this probe has extremely high distance resolution.

Furthermore, in this embodiment, an acoustic matching layer 16 is laminated on the surface of the transducer 12 to ensure matching with the object, thereby suppressing the reflection of ultrasonic waves generated at the interface between the probe and the object. be able to. Therefore, the sensitivity of this probe is improved, and the ultrasonic diagnostic image of the subject obtained through this probe can also have higher distance resolution.
Note that this acoustic matching layer 16 does not need to be formed integrally with the probe as in this embodiment, and may not need to be used depending on the type of subject or the part to be inspected.

In addition, in order to improve the adhesion at the interface between the probe and the subject, the opening of the rotating surface of the probe, that is, the opening of the acoustic matching layer 16, for example, as shown in FIG. The filler 18 may be filled with a flat portion. This filler 18 can be formed using, for example, low impedance polyester.

Next, a method for manufacturing an ultrasonic probe according to the present invention will be explained.

For example, when manufacturing a probe as shown in FIG. 3, there is a problem in that the polymer piezoelectric film, which is commonly used as the material for the ultrasonic transducer 12, loses its polarization when it is exposed to heat. Therefore, in the method of the present invention, first, the acoustic backing material 10, the ultrasonic vibrator 12, and the acoustic matching layer 16, each having a surface in the shape of a rotating surface of two circular arcs, are heat compression molded, and then The above-mentioned vibrator 12 is polarized, and the acoustic backing material 10 and the vibrator 1 are
2. A probe is formed by laminating the acoustic matching layer 16 in this order. Here, since the polarization operation of the vibrator 12 can be performed after the vibrator 12 is thermally compression molded,
After the thermocompression molded members 10, 12, and 16 are successively bonded together, the vibrator 12 may be polarized.

As described above, according to the present invention, it is possible to obtain an ultrasonic probe that performs virtual ring focusing without using an acoustic lens by making the vibration surface of the ultrasonic transducer into a rotating surface shape of two circular arcs. Can be done.
As a result, like the conventional virtual ring-shaped ultrasonic probe, it has a sharp directivity from short to long distances while sufficiently suppressing sub-maximum, and eliminates the need for the conventional acoustic lens. As a result, it is possible to obtain extremely clear ultrasonic diagnostic images by preventing a decrease in distance resolution caused by multiple reflections within the acoustic lens.

In addition, a polymer piezoelectric film is thermally compression molded to form an ultrasonic transducer whose vibrating surface has the shape of a rotating surface with two circular arcs, and then this transducer is polarized to form an ultrasonic probe. This prevents the polarization characteristics of the resonator from being affected by heat.
An ultrasonic probe having the above effects can be efficiently manufactured.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the cross-sectional structure of a conventional ultrasound probe, Fig. 2 is an explanatory diagram of its virtual ring sound source,
FIG. 3 is an explanatory diagram showing the cross-sectional structure of an embodiment of the ultrasonic probe according to the present invention, and FIG. 4 is an explanatory diagram showing another embodiment of the present invention. Corresponding members in each figure are designated by the same reference numerals, and 10
is an acoustic backing material, 12 is an ultrasonic vibrator, 16
is the acoustic matching layer.

Claims (1)

[Scope of Claims] 1. In an ultrasonic probe that transmits and receives ultrasonic waves toward a subject from an ultrasonic transducer laminated on an acoustic backing material, the vibration surface of the ultrasonic transducer is shaped like two circular arcs. An ultrasonic probe formed in the shape of a rotating surface, and characterized in that the ultrasonic virtual ring sound source is arranged behind the vibrator. 2. The ultrasonic probe according to claim 1, characterized in that an ultrasonic transducer is laminated on the surface of an acoustic backing material formed in the shape of a rotating surface of two circular arcs. 3. The ultrasonic probe according to claim 1 or 2, characterized in that an acoustic matching layer whose surface is formed into two circular arcs is laminated on the vibration surface of the ultrasonic transducer. probe. 4. A polymeric piezoelectric film is thermally compression molded to form an ultrasonic vibrator whose vibrating surface has a rotating surface shape of two circular arcs and a virtual ring sound source of ultrasonic waves arranged behind it. 1. A method of manufacturing an ultrasonic probe, which comprises subjecting the transducer to a polarization operation and laminating the ultrasonic transducer on a pre-formed acoustic backing material.