JP3263158B2 - Ultrasonic probe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe which converts an inputted electric signal into an ultrasonic wave and transmits the same, and converts a received ultrasonic wave into an electric signal and outputs the same.

[0002]

2. Description of the Related Art Ultrasound is transmitted to a subject, especially a human body.
Ultrasound that facilitates the diagnosis of diseases such as internal organs of the human body by receiving the ultrasonic waves that have been reflected back by the tissue in the human body and obtaining a received signal, and displaying an image of the human body based on the received signals. 2. Description of the Related Art Conventionally, a diagnostic apparatus has been used. In this ultrasonic diagnostic apparatus, an electric signal is converted into an ultrasonic wave and transmitted into a subject, and an ultrasonic wave reflected in the subject is received and converted into an electric signal. An ultrasonic probe is used as a transducer.

FIG. 3 is a perspective view schematically showing an example of a conventional ultrasonic probe, and FIG. 4 is a block diagram showing a circuit connected to the ultrasonic probe. A large number of piezoelectric vibrators 1 made of, for example, piezoelectric ceramics (PZT) are arranged in a strip shape in the lateral direction (x direction) in FIG. 3, and a common front electrode 1a electrically connected to each other is formed on the front side thereof. And grounded. On the back side of each piezoelectric vibrator 1, a back electrode 1b independent of each other is formed, and each electrode lead 2 is connected to each back electrode 1b. A matching layer 3 made of an epoxy resin or the like corresponding to each of the piezoelectric vibrators 1 is formed below the piezoelectric vibrator 1 in the drawing.
An acoustic lens 4 made of silicone rubber or the like for converging the ultrasonic waves transmitted from the ultrasonic probe in the y direction (the short axis direction) perpendicular to the arrangement direction (x direction) of the piezoelectric vibrators 1 is provided. Installed. Also, the piezoelectric vibrator 1
In the upper part of the figure, the backing 5 is coupled to the piezoelectric vibrator 1 with the back electrode 1b interposed therebetween for the purpose of shortening the duration of the ultrasound waveform and absorbing the ultrasound transmitted to the back side. .

In order to transmit an ultrasonic wave into a subject (not shown) such as a human body using the ultrasonic probe configured as described above, the transmitting circuit 6 shown in FIG. 1 is transmitted to each of the piezoelectric vibrators 1.
, Ultrasonic waves are transmitted in pulses. Here, the transmission timing of each pulse signal transmitted from the transmission circuit 6 is controlled such that the ultrasonic wave transmitted from each piezoelectric vibrator 1 is focused at a predetermined depth in the subject.

The ultrasonic wave transmitted from the ultrasonic probe and reflected in the subject is received by each piezoelectric vibrator 1 and converted into a received signal. Each of the received signals is appropriately amplified by each of the amplifiers 7 and then input to the delay addition circuit 8, where the focus is applied to a fixed or sequentially changed depth position in the subject. Delay addition is performed so as to be connected.

The received signal subjected to the delay and addition by the delay and addition circuit 8 is input to a signal processing circuit (not shown), and based on the received signal, an image signal representing an image in the subject by ultrasonic waves is generated. An image is displayed on, for example, a CRT display device based on the image signal.

[0007]

In the above-described ultrasonic diagnostic apparatus, it is required to obtain a high-resolution image. This resolution is a detail resolution that indicates how close two reflectors can be separated, and a resolution that indicates how small a difference in the reflection intensity of ultrasonic waves can be identified. It can be divided into contrast resolution.
Of these, the detail resolution is characterized by a -10 dB beam width (see FIG. 6) of an ultrasonic radiation pattern (one way on the outward path) radiated from the ultrasonic probe, and the -10 dB beam width The narrower the, the higher the detail resolution. The contrast resolution is characterized by a beam width spread of −20 dB or less (see FIG. 6), and the narrower the spread, the higher the contrast resolution.

FIG. 5 is a diagram showing a schematic structure of an ultrasonic probe and a radiation sound pressure distribution of an ultrasonic wave radiated from the ultrasonic probe. FIG. 6 is a diagram showing a radiation sound pressure distribution shown in FIG. FIG. 7 shows an intensity distribution in the cross-sectional direction of the ultrasonic beam in the case of distribution.
FIG. 4 is a diagram showing a beam diameter in a depth direction in the subject in that case. When an ultrasonic wave having a uniform radiation sound pressure is transmitted at both the center and the end of the piezoelectric vibrator as shown in FIG. 5, a large side lobe is generated in the ultrasonic beam in the subject as shown in FIG. However, the beam width of -20 dB or less is greatly widened, and the contrast resolution is reduced. As shown in FIG. 7, the region where the ultrasonic beam is narrowed in the depth direction in the subject is short, and therefore the depth of focus is shallow. However, as shown in FIG. 6, the -10 dB beam width is relatively narrow, and thus the detail resolution is relatively good.

FIG. 8 is a diagram showing a schematic structure of an ultrasonic probe and another example of a radiation sound pressure distribution. FIG. 9 is a cross section of an ultrasonic beam in the case of the radiation sound pressure distribution shown in FIG. FIG. 10 is a diagram showing the intensity distribution in the direction, and FIG. 10 is a diagram showing the beam diameter in the depth direction in the subject in that case. As shown in FIG.
There is known a method of transmitting an ultrasonic wave in which the radiated sound pressure is increased in the central portion of the piezoelectric vibrator 1 and becomes smaller toward the end portion. By doing so, side lobes are suppressed as shown in FIG. Therefore, the beam diameter can be narrowed down as a whole as shown in FIG.

Various amplitude weighting methods for realizing the radiation sound pressure distribution as shown in FIG. 8 have been proposed. For example, the polarization intensity is large at the center of each piezoelectric vibrator 1 and decreases toward the short-axis end. (See Japanese Patent Publication No. 24479/1990), devising the shape of each voltage vibrator 1 in the short axis direction so that the area of the piezoelectric vibrator is widened at the center and narrowed toward both ends. (Japanese Patent Publication No. 24480/1990), a method using a backing whose acoustic impedance has changed as a function of position, and the like have been proposed.

By this amplitude weighting, the side lobe level is largely suppressed as shown in FIG.
The beam width of 20 dB or less is narrowed, and the contrast resolution is improved. In addition, as shown in FIG. 10, the area where the beam is narrowed becomes longer, and therefore the depth of focus becomes deeper.
However, when the amplitude weighting is performed (see FIG. 9),
The -10 dB beam width is wider than when no amplitude weighting is performed (see FIG. 6), and the detail resolution is rather deteriorated.

The present invention has been made in view of the above circumstances, and provides an ultrasonic probe having a function of obtaining both an image with good detail resolution and an image with good contrast resolution depending on the application. The purpose is to:

[0013]

A first ultrasonic probe according to the present invention for achieving the above object is an array type ultrasonic probe in which a plurality of piezoelectric vibrators having a rectangular ultrasonic radiation opening are arranged. In the first aspect, the ultrasonic radiation openings of the plurality of piezoelectric vibrators are formed in such a shape that the piezoelectric vibrators arranged closer to the end side than the piezoelectric vibrators arranged closer to the center side have narrower openings. And a first mode using only the first opening of each of the plurality of piezoelectric vibrators, and a second mode which is divided into a second opening including a remaining portion of the first opening. and of the respective piezoelectric vibrators, characterized by comprising a first opening and a switching means for switching a second mode using a rectangular ultrasound radiating aperture <br/> consisting both the second opening Things.

The overall shape of the first opening over the plurality of piezoelectric vibrators is, for example, rhombus.
The second ultrasonic probe of the present invention that achieves the above object is an array-type ultrasonic probe in which a plurality of piezoelectric vibrators having a rectangular ultrasonic radiation opening are arranged. Each of the ultrasonic radiation openings has a first opening formed in a shape having a narrower opening toward the end portion than the center portion side of each piezoelectric vibrator, and a second opening composed of a remaining portion of the first opening. And a first mode using only the first opening of each of the plurality of piezoelectric vibrators, and a first mode and a second opening of each of the plurality of piezoelectric vibrators. And a switching mode for switching between the second mode using a rectangular ultrasonic radiation opening composed of the two.

In the second ultrasonic probe, the first openings of each of the plurality of piezoelectric vibrators are formed, for example, in a rhombus shape. As the switching means in the first ultrasonic probe and the second ultrasonic probe, for example, an analog switch is used.

[0016]

According to the first ultrasonic probe of the present invention, only the first opening and both the first opening and the second opening are switched and used, and are arranged on the center side. Since the first opening of the piezoelectric vibrator arranged closer to the end portion than the first opening of the piezoelectric vibrator is formed to be sequentially narrower, the scanning in the short axis direction and the scanning can be performed by using only the first opening. The beam can be narrowed in both directions, so that an ultrasonic image with good contrast resolution can be obtained. As for the scanning direction, a method of adjusting the transmission timing of the pulse signal to be applied to each piezoelectric vibrator and adding a delay as in the related art can be used together. Also, the first
Ultrasonic radiation consisting of both the first and second openings
When an aperture is used, an ultrasonic beam having a uniform sound pressure distribution in the short-axis direction is transmitted and received, whereby an ultrasonic image with good detail resolution can be obtained. In this case, in the scanning direction in which the piezoelectric vibrators are arranged, an ultrasonic beam having a predetermined width is formed by adjusting the transmission / reception timing of the pulse signal applied to each piezoelectric vibrator and by delay addition (see FIG. 4).

Further, in the second ultrasonic probe of the present invention, the ultrasonic radiation aperture of each of the plurality of piezoelectric vibrators arranged is narrower on the shorter side than the center side of each piezoelectric vibrator. Since it is divided into a first opening formed in a shape and a second opening composed of a remaining portion of the first opening,
Depending on whether only the first aperture is used or whether a rectangular ultrasonic radiation aperture composed of both the first aperture and the second aperture is used, an image with good contrast resolution and detail resolution in the short-axis direction, respectively. Good image can be obtained. In the scanning direction, the beam diameter is adjusted by adjusting the transmission timing of the pulse signal and adding delay (see FIG. 4) as in the related art.

[0018]

Embodiments of the present invention will be described below. FIG. 1 is a schematic view showing an embodiment of the first ultrasonic probe of the present invention. This ultrasonic probe is an array type ultrasonic probe in which a plurality of piezoelectric vibrators 1 each having a rectangular ultrasonic radiation opening are arranged in the scanning direction. The ultrasonic opening of each piezoelectric vibrator 1 is shown in FIG. The first opening 11 and the second opening 12
Is divided into The first opening 11 is formed in a shape in which the piezoelectric vibrators arranged on the end in the scanning direction sequentially have narrower openings than the piezoelectric vibrators arranged on the center side, and in this embodiment, The first opening 11 is formed in a diamond shape as a whole.

The second opening 12 is formed by the remaining portion of the first opening 11 of each piezoelectric vibrator 1 having a rectangular ultrasonic radiation opening. An electrode lead 2 is attached to each piezoelectric vibrator 1, and the electrode lead 2 is connected to only the first opening 11 or the first opening 1 by an analog switch 9.
The connection is switched so as to be connected to both the first opening 12 and the second opening 12.

In this embodiment, when the electrode lead 2 is connected only to the first opening 11, the amplitude weighting is performed not only in the short axis direction but also in the scanning direction. The adjustment of the beam diameter in the scanning direction is not only caused by the shape of the first opening 11, but also by adjusting the transmission timing of a pulse signal applied to the electrode lead 2 and reflected by the subject to be received by the piezoelectric vibrator 1. This is also performed by delay addition of the obtained ultrasonic waves.

By using only the first opening 11 in this embodiment, a radiation sound pressure as shown in FIG. 1B can be obtained in the short axis direction, whereby the side rope as shown in FIG. A suppressed ultrasonic beam can be obtained, and thus an image with good contrast resolution can be obtained. Also, by using both the first opening 11 and the second opening 12, that is, a rectangular ultrasonic radiation opening, it is possible to obtain an ultrasonic beam having a narrow beam width of −10 dB as shown in FIG. 6, In this case, an image with good detail resolution can be obtained. Adjustment of the beam diameter in the scanning direction is performed by adjusting the transmission timing of the pulse signal applied to the electrode lead 2 and delaying and adding the ultrasonic waves reflected within the subject and received by the piezoelectric vibrator 1 as in the related art.

FIG. 2 is a schematic diagram showing an embodiment of the second ultrasonic probe according to the present invention. This ultrasonic probe is an array type ultrasonic probe in which a plurality of piezoelectric vibrators 1 each having a rectangular ultrasonic radiation opening are arranged in the scanning direction, as in the embodiment shown in FIG. The ultrasonic radiation aperture of each piezoelectric vibrator 1 has a first aperture 11 and a second aperture 12 as shown.
In this embodiment, each of the piezoelectric vibrators 1 is divided.
, The first openings 11 all have the same shape,
The first opening 11 of each piezoelectric vibrator 1 has an opening that is narrower toward the short-axis direction end side than the center side of each first piezoelectric vibrator 1, and each is formed in a rhombus shape. Second opening 12
Represents the first opening 1 of the ultrasonic radiation openings of each piezoelectric vibrator 1.
1 is formed.

An electrode lead 2 is attached to each piezoelectric vibrator 1, and the electrode lead 2 is connected to only the first opening 11 or between the first opening 11 and the second opening 12 by an analog switch 9. It is switched to be connected to both. In this embodiment, the electrode lead 2 is connected to the first opening 11.
If only connection is made, amplitude weighting is performed in the short axis direction. The adjustment of the beam diameter in the scanning direction is performed by adjusting the transmission timing of the pulse signal applied to the electrode lead 2 and by delay addition of the ultrasonic waves reflected within the subject and received by the piezoelectric vibrator 1.

By using only the first aperture 11 in this embodiment, it is possible to obtain an ultrasonic beam with suppressed side lobes as shown in FIG. 9, as in the case of the embodiment shown in FIG. Therefore, an image with good contrast resolution can be obtained. In addition, by using both the first opening 11 and the second opening 12, that is, a rectangular ultrasonic radiation opening, -10 dB as shown in FIG.
In this case, an ultrasonic beam having a small beam width can be obtained, and in this case, an image having good detail resolution can be obtained.

[0025]

As described above, according to the first and second ultrasonic probes of the present invention, the rectangular ultrasonic radiation opening of the piezoelectric vibrator is at least shorter than the central part in the short axis direction. It is divided into a first opening having a smaller area toward the side and a second opening having a remaining portion, and only the first opening or the first opening is divided.
It is configured so that a rectangular opening formed by combining the opening of the first opening and the second opening can be used by switching, so that both an image having good detail resolution and an image having good contrast resolution can be obtained depending on the application. it can.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of a first ultrasonic probe according to the present invention.

FIG. 2 is a schematic view illustrating an embodiment of a second ultrasonic probe according to the present invention.

FIG. 3 is a perspective view schematically showing an example of a conventional ultrasonic probe.

FIG. 4 is a block diagram showing a circuit connected to the ultrasonic probe shown in FIG.

FIG. 5 is a diagram showing a schematic structure of an ultrasonic probe and a radiation sound pressure distribution of ultrasonic waves emitted from the ultrasonic probe.

6 is a diagram showing an intensity distribution in the cross-sectional direction of the ultrasonic beam in the case of the radiation sound pressure distribution shown in FIG.

FIG. 7 is a diagram showing a beam diameter in a depth direction inside a subject in the case of the radiation sound pressure distribution shown in FIG.

FIG. 8 is a diagram showing a schematic structure of an ultrasonic probe and another example of a radiation sound pressure distribution.

9 is a diagram illustrating an intensity distribution in a cross-sectional direction of an ultrasonic beam in the case of the radiation sound pressure distribution illustrated in FIG. 8;

10 is a diagram illustrating a beam diameter in a depth direction in a subject in the case of the radiation sound pressure distribution illustrated in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 2 Electrode lead 9 Analog switch 11 1st opening 12 2nd opening

Claims (5)

(57) [Claims] 1. An array-type ultrasonic probe in which a plurality of piezoelectric vibrators having a rectangular ultrasonic radiation opening are arranged, wherein the ultrasonic radiation openings of the plurality of piezoelectric vibrators are arranged on a center side. A first piezoelectric vibrator arranged closer to the end than the piezoelectric vibrator has a narrower opening in the first shape.
And a first mode using only the first opening of each of the plurality of piezoelectric vibrators, and a second mode which is divided into a second opening including a remaining portion of the first opening. the piezoelectric vibrator, respectively, the second using a rectangular ultrasound radiating aperture consisting of both the first and second openings
An ultrasonic probe comprising a switching means for switching between the modes. 2. The ultrasonic probe according to claim 1, wherein an entire shape of the first opening over the plurality of piezoelectric vibrators is formed in a rhombus. 3. An array-type ultrasonic probe in which a plurality of piezoelectric vibrators having a rectangular ultrasonic radiation opening are arranged, wherein each of the plurality of piezoelectric vibrators has an ultrasonic radiation opening,
Each of the piezoelectric vibrators is divided into a first opening formed in a shape having an opening narrower toward an end side than a center side, and a second opening including a remaining portion of the first opening. And a first mode using only the first opening of each of the plurality of piezoelectric vibrators, and a rectangular mode formed by both the first opening and the second opening of each of the plurality of piezoelectric vibrators.
An ultrasonic probe comprising switching means for switching between a second mode using an acoustic wave radiation aperture and a second mode. 4. The ultrasonic probe according to claim 3, wherein said first openings of each of said plurality of piezoelectric vibrators are formed in a diamond shape. 5. The ultrasonic probe according to claim 1, wherein said switching means is an analog switch.