JPS60208196A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To obtain an ultrasonic probe with high reliability whose acoustic impedance is selected optionally by constituting the probe with a piezoelectric vibrator and a back load and adopting the constitution for the back load where a micro balloon and metallic powder are packed to a thermosetting resin. CONSTITUTION:Single or multi-layered acoustic matching layers 12, 13 are provided as required to a side of the piezoelectric vibrator 11 in contact with an object to be detected, and an acoustic lens 17 is provided as required further and an ultrasonic wave 6 is irradiated from the acoustic lens 17 by impressing an electric signal controlled externally to an electrode 14 in the vibrating direction of the piezoelectric vibrator 11. The back load member 15 is formed by pouring or bonding a molded back load agent 15 to the opposite side of the piezoelectric vibrator 11. As the back load agent 15, the epoxy resin being a thermosetting resin packed with micro balloon and tungsten powder is used.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasound probe used in a medical ultrasound diagnostic apparatus.

Conventional Structure and Problems Conventional ultrasound probes, particularly probes used in medical ultrasound diagnostic equipment, generally have a structure as shown in FIG. FIG. 1 shows a general structure where m is used in a linear electronic scanning ultrasonic probe in which strip-shaped piezoelectric sensors 1 are arranged in a straight line.

The one in FIG. 1 has a configuration in which one or more acoustic matching layers 2 are provided on a piezoelectric vibrator 1, and an electrical signal controlled from the outside is applied to an electrode 4 provided in the vibration direction of the piezoelectric vibrator 1. The ultrasonic wave 6 is radiated from the acoustic matching layer 2 side by applying . The main characteristics required of this back loading material 6 are (1) high hardness;
(2) be uniform; (3) have a large sound wave attenuation coefficient; and (4) have a predetermined acoustic impedance value. Item (1) is a characteristic related to the mechanical strength of the probe vibrator surface and the arrangement accuracy of the piezoelectric vibrator, and if the hardness is low, it may cause mechanical damage to the probe vibrator surface or the piezoelectric vibrator alignment accuracy. This causes disturbances in sound field characteristics and deterioration of ultrasound image characteristics. ? ) is related to the uniformity of the probe characteristics. (3)
The terms are related to the shape and size of the back loading material 2 weight, and if the sound wave attenuation coefficient is small, the back loading material must be made large, and the probe size.

It is also large and heavy. The term ←) is a characteristic related to the sensitivity of the probe, and if the acoustic impedance is dog-like, the sensitivity of the probe will decrease as a result.

Conventionally, this back load material 6 has been made of a plastic material filled with tungsten powder, ferrite rubber, plastic, or urethane rubber filled with Galanu hollow bodies.
It is not an excellent material in all characteristic values such as Hz) and acoustic impedance values.

In other words, the conventional back loading materials mentioned above are, for example, plastic materials filled with tungsten powder, which have excellent hardness characteristics, but have relatively high acoustic impedance values of 6 to 2o x 1o5 or 101"K, and ferrite rubber has ,
The urethane rubber material has better sound attenuation characteristics than the above plastic material, but has slightly inferior hardness characteristics.
Currently, each material has its advantages and disadvantages, such as the fact that while it can lower acoustic impedance compared to the plastic material and ferrite rubber material, it has slightly inferior sound wave attenuation characteristics.

Furthermore, in order to improve probe characteristics or to reduce size and weight, it is necessary to further improve the above-mentioned characteristic value of K. Therefore, it has been a big challenge to develop a material that has all the properties that are equal to or better than those of the conventional back-loading materials.

Purpose of the Invention The present invention was made in order to solve the above-mentioned conventional problems.Acoustic impedance can be arbitrarily selected, and furthermore, the hardness and hardness of all conventional back loading materials can be improved.
The objective is to provide a small, highly reliable ultrasonic probe with uniform characteristics, equipped with a new back loading material with a characteristic value equal to or higher than the acoustic wave attenuation coefficient value. be.

Structure of the Invention To achieve this object, the present invention is characterized in that it is composed of at least a piezoelectric vibrator and a back load, and the back load is made of a thermosetting resin filled with microballoons and metal powder. The present invention provides an ultrasonic probe with the following features.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a perspective view showing an ultrasonic probe according to an embodiment of the present invention. (shown) are provided, and if necessary, an acoustic lens 17 is further provided, and an electrical signal controlled from the outside is applied to the electrode 14 provided in the vibration direction of the piezoelectric vibrator 11. As a result, the ultrasonic waves 6 are emitted from the acoustic lens 17 side. On the opposite side of the piezoelectric vibrator 11, a back load material 16 is formed by pouring, or a molded back load material 15 is bonded. Note that one end face of the rear load shield 15 may have an uneven structure as shown in the figure in order to scatter ultrasonic waves. This backside loading material is made of epoxy resin, which is a thermosetting resin, filled with microballoons and tungsten powder.

Figure 3 shows the characteristics of the back loading material of the above example, in which epoxy resin 2023/2103 (manufactured by Yokohama Three Bond) is used as the base material, and plastic micro balloons with a particle size of around 60 microns are made of epoxy resin. The f't impedance and the sound wave absorption coefficient characteristics at 3 MHz are shown when the tungsten powder is filled at 3% by weight and the filling amount of tungsten powder is taken as a parameter. In Figure 3, for example, the filling weight ratio of tungsten to epoxy resin is 250%.
In the case of , the acoustic impedance Z is 3.1×105y/C
The sound wave absorption coefficient α at n1 is 26 dB/m (3 MHz)
It is.

The hardness is 86 or more in Shore D. (96 of Shore A can be considered to be equivalent to 6o of Shore D) Eliminate unnecessary reflection of sound waves from the end face of the back load material 16 facing the surface to which the piezoelectric vibrator 11 is attached, and In order to obtain a wide signal dynamic range, a back loading material with a large acoustic wave absorption coefficient is desirable. For example, if a dynamic range of 160 dB is required, the material with a sound wave absorption coefficient of 26 d B /ax in this example only needs to have a thickness of 29 mm or more in order to eliminate reflection from the end face of the back load material, and the sound wave absorption coefficient is 26 d B /ax. Even if compared only with the conventional back load using urethane rubber as the base material,
In the case of ferrite rubber, a thickness of 8.3 JlK or more is required, and the ultrasonic probe can be significantly miniaturized.

As another example, when a microballoon is made of epoxy resin as a base material, the weight ratio to the epoxy resin is 6φ, and the tungsten powder is filled 100% at the same weight ratio, the acoustic impedance and the sound wave attenuation coefficient are 1. ox
105y/cM, yx, 1e dB/sm.

The acoustic impedance and sound attenuation coefficient when filled with Mata Micro Balloon and tungsten powder at a weight ratio of 2% and 500%, respectively, are 6. ox105f/cr
By varying the amounts of micro balloons and tungsten powder filled in the epoxy resin, the acoustic attenuation coefficient (3MHz) is approximately 16 to 28 dB/B, and the acoustic impedance is approximately 16 to 28 dB/B. Backload materials ranging from about 1.0 to 6, OX 105f/crl@SEL were obtained. Of course, these hardness values showed a value of 86 or more in Nyoa D.

The hardness of the back loading material 16 is directly related to the mechanical strength of the probe, and the harder it is, the more desirable it is. Further, in order to uniformly arrange a large number of strip-shaped piezoelectric vibrators 11 on a straight line on the back load material 16 with high accuracy, it is desirable that the back load material 16 is hard. Incidentally, in the case of this embodiment, since an epoxy resin is used as the base material, the hardness is several steps harder (Shore D 86) than conventional ferrite rubber (Shore A 96 to 98). Therefore, it is possible to uniformly arrange a large number of piezoelectric vibrators 11 on the back load material 16 with good n degrees of uniformity. From the above, it is possible to obtain a highly reliable, uniform, and high-performance probe.

In the back loading material according to this example, the case where epoxy resin is used as the base material has been described, but in the present invention, the base material may be polystyrene, polyurethane,
It is clear from their properties that it can also be applied to polyester, polyethylene, etc.

Further, as the microballoon, a mixture of either a plastic hollow body or a glass hollow body is suitable.

Further, in the back loading material for the ultrasonic probe of the present invention, the metal powder filled in the thermosetting resin includes lead, molybdenum, and tantalum in addition to tungsten powder.

It is clear that the present invention can also be applied to ferrite, tungsten carbide, etc.

In addition, the back loading material according to the ultrasonic probe of the present invention, after all the piezoelectric vibrators, acoustic matching layers, acoustic lenses, etc. are configured,
It is also possible to manufacture by pouring the material. Furthermore, in the embodiment, a case has been described in which the piezoelectric vibrators are applied to a so-called array-type ultrasonic probe in which piezoelectric vibrators are arranged in a linear manner. It is clear that the present invention can be applied to various ultrasonic probes such as arcuate array ultrasonic probes.

Effects of the Invention As described above, the present invention is characterized in that a material made of a thermosetting resin filled with micro balloons and metal powder is provided as a back load on one of the sound wave transmitting and receiving sides of a piezoelectric vibrator that transmits and receives sound waves. Since the back loading material has a large sound wave absorption coefficient, the back loading material can be made extremely thin and the probe can be made significantly smaller. Further, since the hardness is high, a large number of piezoelectric vibrators can be arranged uniformly and accurately on the backside loading material, and therefore a high-performance probe with uniform characteristics can be obtained. In addition, the mechanical strength is high, and damage to the transducer surface of the probe can be prevented, making it possible to obtain a highly reliable probe. on the other hand,
Acoustic impedance value is also 1 to 6 x 1o5y/cdsec
This can be achieved over a wide range of conditions, and can be selected and used depending on the characteristics (sensitivity) required of the probe.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a conventional ultrasonic probe, Fig. 2 is a perspective view of an ultrasonic probe in an embodiment of the present invention, and Fig. 3 shows the acoustic characteristics of the back loading material in the embodiment. This is a graph showing. 11. Piezoelectric vibrator, 12.13. Acoustic matching layer, 16
Back load material, 17... Acoustic lens. Name of agent Patent attorney Satoshi Nakao Male Female or 1st person
1! ! !

Claims (1)

[Scope of Claims] (1) A piezoelectric vibrator that transmits and receives sound waves, and a back load provided on a side opposite to the side of the piezoelectric vibrator that contacts the subject, wherein the back load is made of thermosetting resin. An ultrasonic probe characterized by being made of a material filled with at least a microballoon and metal powder. ? ) Thermosetting resins include epoxy resin, polystyrene resin, polyurethane resin, and polyester resin. The ultrasonic probe according to claim 1, characterized in that it is made of one of polyethylene resins. (3) The ultrasonic probe according to claim 1, wherein the microballoon includes at least one of a hollow glass body and a hollow glass body. (4) Metal powder is tungsten, lead, or molybdenum. The ultrasonic probe according to claim 1, characterized in that it is made of tantalum, ferrite, or tungsten carbide.