JP2000287300A - Device for testing characteristic of ultrasonic wave transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and accurately adjust a relative position relation between an ultrasonic wave transducer and a target section of an ultrasonic wave beam sent from this ultrasonic wave transducer b a biaxial angle adjustment means in the case of testing the characteristic of the ultrasonic wave transducer. SOLUTION: An ultrasonic wave prove 7 provided with an ultrasonic wave transducer is mounted on a positioning arm 26 of an angle adjustment means 20 and a hydrophone 11 as a target member receives a ultrasonic wave. The hydrophone 11 uses a scanning means 13 to scan a prescribed scanning plane RP, and an angle of the ultrasonic wave transducer is adjusted by a θ stage 28 and a tilt stage 33 being components of the angle adjustment means 20, the ultrasonic wave transducer is placed on an extension line of the turning center of the θstage 28 and the sound axis center of the ultrasonic wave transducer is placed at the center of a circular arc of the slide face 35a of a tilt table 35 by the tilt stage 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transducer characteristic testing apparatus for inspecting and measuring the transmission characteristics and the like of an ultrasonic transducer mounted on an ultrasonic probe or the like for examining the state of a body tissue of a subject. It is about.

[0002]

2. Description of the Related Art An ultrasonic transducer has an ultrasonic transducer as an element for converting electric energy of a piezoelectric element or the like into mechanical vibration energy or conversely converting mechanical energy into an electric signal. The transmission / reception surface of the ultrasonic transducer is provided with an acoustic matching layer on the transmission / reception surface, and a backing material is attached on the opposite side. Ultrasonic transducers are widely used, for example, in the medical field. An ultrasonic transducer for this kind of medical use is incorporated as an ultrasonic probe together with scanning means and the like, and is inserted into the body epidermis of the subject, or into the body cavity and from the inner wall of the body cavity,
The ultrasonic transducer is driven so as to transmit an ultrasonic pulse toward the body and receive a reflected echo from a tomographic portion of the body tissue with the ultrasonic transducer. Then, by performing an imaging process on the received signal by the ultrasonic observation apparatus, information on the tissue state in the body is displayed on the monitor as an ultrasonic image. Diagnosis or the like for detecting a tumor or other lesion can be performed based on the ultrasonic image.

An ultrasonic transducer is composed of a multilayer body comprising at least a backing material, an ultrasonic vibrator, and an acoustic matching layer. On the acoustic matching layer, an acoustic lens for focusing an ultrasonic beam at a predetermined position is mounted. There are also things. In order to evaluate and verify the characteristics of the ultrasonic transducer configured as described above, tests and measurements on the characteristics of the ultrasonic wave are performed. In this characteristic test, for example, a reflector is disposed at a predetermined position in a test tank containing a homogeneous ultrasonic transmission medium such as degassed water, and an ultrasonic transducer is disposed to face the reflector, and Transmit the ultrasonic beam from the ultrasonic transducer and reflect it on this reflector,
This is performed by receiving the reflected echo with an ultrasonic transducer. Then, by performing predetermined processing on the reception signal of the ultrasonic transducer by the signal processing circuit, data relating to the transmission / reception characteristics of the ultrasonic transducer is obtained.

[0004]

In the test apparatus of the prior art described above, since the ultrasonic transducer and the reflector are mounted on separate support members, accurate alignment between them is required. Is difficult, and when measuring a plurality of ultrasonic transducers, there is an inconvenience that measurement cannot be performed under the same conditions due to an attachment error or the like. Further, since the support member of the ultrasonic transducer and the support member of the reflection plate are fixedly held, the measurement point is one place, and the test is performed by changing the relative position between the ultrasonic transducer and the reflection plate, for example, Tests such as measurement of the entire image of the sound field cannot be performed, and it is not always satisfactory as an inspection / measurement device for the characteristics of the ultrasonic transducer.

The present invention has been made in view of the above points, and an object of the present invention is to perform an ultrasonic transducer characteristic test and to transmit an ultrasonic transducer and a signal transmitted from the ultrasonic transducer. The relative positional relationship between the ultrasonic beam and the target member
In addition, the purpose is to allow accurate adjustment.

[0006]

According to the present invention, there is provided an ultrasonic transducer for receiving or reflecting ultrasonic waves in a test tank containing an ultrasonic transmission medium in order to perform a characteristic test of the ultrasonic transducer. A target member to be installed, and an ultrasonic beam is emitted from the ultrasonic transducer toward the target member, and a support member that supports one of the ultrasonic transducer and the target member is formed by a biaxial angle. The angle adjusting means is connected to an adjusting means, and the angle adjusting means is for rotating the ultrasonic transducer or the target member about two orthogonal axes passing substantially through the central position of transmission / reception or reflection. A θ stage extending in one axial direction of the shaft and rotating the support member about the axis, and the other of the two orthogonal axes In order to rotate around, about said center position, and its characterized by being configured with a tilt stage for arcuate movement of the support member.

As a specific configuration, for example, an ultrasonic probe incorporating an ultrasonic transducer is detachably mounted on a support member provided on the angle adjusting means, and a target member is an ultrasonic probe from the ultrasonic transducer. It is composed of a hydrophone that receives a signal, and is attached to a scanning unit that scans the hydrophone on a substantially vertical plane, and the scanning unit is attached to an interval adjusting unit that moves the hydrophone close to and away from the ultrasonic probe. It can be configured as follows.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, in FIG. 1, reference numeral 1 denotes an ultrasonic transducer, and this ultrasonic transducer 1 has an acoustic matching layer 3 on the surface side of an ultrasonic vibrator 2 and an acoustic lens 4 joined to the acoustic matching layer 3. A backing material 5 is provided on the back surface of the ultrasonic transducer 2. When a predetermined voltage is applied to the ultrasonic transducer 2, an ultrasonic beam is transmitted. The ultrasonic beam is called a short-range sound field NS from the ultrasonic transducer 1 to a distance DS. In the short-range sound field NS, the ultrasonic beam is substantially composed of a plane wave, and its sound pressure distribution has a complicated stripe shape. And the distant sound field F beyond the distance DS
At S, the ultrasonic beam becomes a spherical wave and starts to spread. In the far-field sound field FS, a sound field having a spherical spread around the sound axis SA is formed.
Then, by attaching the acoustic lens 4 to the ultrasonic transducer 1, as shown by the phantom line in FIG. 1, the far sound field FS has a minimum beam cross section at a position away from the ultrasonic transducer 1 by a predetermined distance. Focused so that Here, the acoustic lens 4 for narrowing the ultrasonic beam has a concave lens based on the difference in sound speed between the lens and a medium other than the lens, when the sound speed of the lens is faster,
If the sound speed of the lens is lower, a convex lens is used.

The ultrasonic transducer 1 having the above-described structure is, for example, as shown in FIG.
A cap 6 having good acoustic characteristics is mounted on the tip of the probe, and the ultrasonic probe 7 is mounted in the cap 6 and performs ultrasonic scanning in a linear direction or a radial direction. If the hollow shaft 5 is formed of a small-diameter, flexible tube material, the treatment instrument insertion channel or the like provided in the endoscope is guided into the body cavity as a guide means, and ultrasonic waves are transmitted from the inner wall of the body cavity. Is configured as a so-called body-insertable ultrasonic probe 7 for acquiring tomographic information of a tissue in the body by performing transmission and reception. Also, there are various forms of ultrasonic probe incorporating an ultrasonic transducer,
In addition, there are various types of operation modes and scanning methods of the ultrasonic transducer. In the present invention, not only the ultrasonic probe 7 shown in FIG. 2 but also an ultrasonic transducer incorporated in various types of ultrasonic probes, or a characteristic test of the ultrasonic transducer alone can be performed.

As described above, the characteristics of the ultrasonic beam transmitted from the ultrasonic transducer 1 incorporated in the ultrasonic probe 7, such as the depth reach on the sound axis, the effective beam diameter, the focal length, and the focal position. It is possible to acquire data on the beam diameter and its sound pressure, as well as the state and degree of the side lobe. The specific configuration of the characteristic test apparatus for this purpose is shown in FIGS.

Thus, the ultrasonic beam emitted from the transmitting / receiving surface 1a of the ultrasonic transducer 1 travels with a spatial spread. It differs depending on the acoustic lens 4 and the like. Now, if the transmitting / receiving surface 1a is circular and the acoustic lens 4 for converging the ultrasonic beam is disposed on the surface, the ultrasonic beam emitted from the ultrasonic transducer 1 in a homogeneous ultrasonic transmission medium In the distant sound field FS, the cross-sectional shape becomes a substantially circular shape, proceeds in the direction of the sound axis SA while maintaining this circular pattern, continuously converges up to the focal position of the acoustic lens 4, and thereafter continuously. It becomes a shape that expands. Therefore, when a sound pressure distribution on a plane orthogonal to the sound axis SA is detected at a certain position on the sound axis SA, a sound pressure distribution of a cross section of the sound field at the position, that is, a sound field pattern is obtained. In addition, by sequentially acquiring sound field patterns at predetermined pitch intervals along the sound axis SA, an overall image of the sound field of the ultrasonic beam can be obtained. Therefore, from the sound field pattern which is information on the sound pressure distribution in the direction orthogonal to the sound axis, the characteristics of the ultrasonic beam, that is, the ultrasonic penetration depth, effective beam diameter, the focal length and the beam diameter at the focal position and its Data on sound pressure,
Further, it is possible to measure the state of the side lobe and the like.

FIG. 3 shows a schematic configuration of the test apparatus. In FIG. 1, reference numeral 10 denotes a test tank in which an ultrasonic transmission medium having a low ultrasonic attenuation rate, such as degassed water, is stored. The ultrasonic probe 7 is provided in the test tank 10. An ultrasonic beam is transmitted while the ultrasonic transducer 1 is immersed in an ultrasonic transmission medium. Then, a hydrophone 11 as a target member of the ultrasonic beam is disposed opposite to the ultrasonic probe 7 in the ultrasonic transmission medium, and the hydrophone 1
1 receives an ultrasonic wave and detects the received sound pressure level. Here, the hydrophone 11 has the receiving part 12 provided at the tip of the needle-like part 11a, and therefore receives the ultrasonic wave substantially at a point. To obtain a sound field pattern in a cross section at a predetermined position of the ultrasonic beam by the hydrophone 11,
Is mounted on a scanning means for scanning with a planar spread. Further, in order to scan the hydrophone 11 at a plurality of positions along the sound axis SA of the ultrasonic beam, the sound axis S
An interval adjusting means for displacing in the A direction is provided.

The scanning means 13 is provided at an upper position of the test tank 10. The scanning unit 13 is mounted on a Z-axis robot 14 as an interval adjusting unit.
It comprises a Y-axis scanning unit 13Y which is connected to the Z-axis robot 14 so as to be movable in the vertical direction, and an X-axis scanning unit 13X which is mounted on the Y-axis scanning unit 13Y so as to be movable in the horizontal direction. The hydrophone 11 has a shaft portion 11b detachably connected to a lower end portion of a support arm 15, and an upper end portion of the support arm 15 is fixed to the X-axis scanning section 13X. Therefore, the hydrophone 11 is scanned in one direction (X-axis direction) by the X-axis scanning unit 13X, and is scanned in a direction orthogonal to the X-axis (Y-axis direction) by the Y-axis scanning unit 13Y. The X-axis and Y-axis scanning units 13X, 13
Driving of Y can be performed by a known ball screw feeding means or the like.

The receiving section 12 of the hydrophone 11 receives an ultrasonic beam emitted from the transmitting / receiving surface 1a of the ultrasonic transducer 1 in the ultrasonic probe 7 while scanning a predetermined scanning surface by the above-described scanning means 13. .
Here, as shown in FIG. 4, when the scanning surface of the hydrophone 11 is RP and the transmitting surface of the transmitting / receiving surface 1a of the ultrasonic transducer 1 is EP, at least the scanning surface RP is parallel to the transmitting surface EP. Must be.
In other words, the scanning plane RP includes the center position O of the transmission plane EP, and the sound axis SA in the direction orthogonal to the transmission plane EP from the center position O exists. Must be. For this purpose, it is necessary to adjust the angle of either the scanning plane RP or the transmission plane EP. In the present embodiment, an angle adjustment mechanism is provided on the transmission surface EP side, and the sound axis SA is adjusted so as to swing vertically and horizontally by the angle adjustment mechanism. Align so that it faces in the direction orthogonal to. To this end, the transmission surface E
P has x, y orthogonal 2 centered on the transmission center position O.
An axis is set, and the angle is adjusted by rotating around the x-axis and the y-axis.

For this purpose, the ultrasonic transducer 1
Is detachably attached to the support member 21 of the biaxial angle adjusting means 20 in a state of being incorporated in the ultrasonic probe 7. Here, the angle adjusting means 20 is mounted on a mounting member 24 connected to a post 22 erected outside the test tank 10 so as to be rotatable up and down around a swing shaft 23. Accordingly, when the mounting member 24 is arranged at the horizontal position shown by the solid line in FIG. 3, the ultrasonic probe 7 mounted on the support member 21 is immersed in the ultrasonic transmission medium of the test tank 10 and the ultrasonic transducer 1 When the ultrasonic probe 7 is rotated upward about the swing shaft 23 and displaced to the position indicated by the imaginary line, the ultrasonic probe 7 is attached to and detached from the support member 21.

The support member 21 includes a base 25 and the base 25.
And a positioning arm 26 which is exchangeably connected to the positioning arm 26. A positioning groove 26a (see FIG. 5) is formed in the positioning arm 26 in the axial direction. The ultrasonic probe 7 is housed in the positioning groove 26a, and a stopper provided at the tip of the positioning arm 26. Part 26
b. As a result, the ultrasonic probe 7 is mounted on the positioning arm 26 based on its outer shape. Further, in order to hold the ultrasonic probe 7 fixedly in this mounted state, a tightening band 27 made of a ring-shaped elastic member is mounted on the positioning arm 26 at at least two places.

The two-axis angle adjusting means 20 is for aligning the ultrasonic transducer 1 provided on the ultrasonic probe 7. The angle adjusting means 20 has a θ stage 28 connected to the mounting member 24, and the θ stage 28
The rotary table 30 is mounted so as to be rotatable in the horizontal direction. The rotary table 30 can be driven to rotate at a desired angle by a feed screw 31 and can be fixed at a desired angular position by a stopper screw 32. Has become. The rotary table 30 has a tilt stage 3
3 is attached, and the fixed base 34 is formed with an arc-shaped guide surface 34a. Further, a tilt table 35 that tilts along the guide surface 34a is connected to the fixed base 34, and the tilt table 35 includes an arc-shaped slide surface 35a that slides along the guide surface 34a. Further, the fixed table 34
A feed screw 36 is provided on the side.
When the rotary table 6 is rotated, the tilt surface of the tilting table 35 is slid along the guide surface 34a, and the tilt angle is adjusted. A stopper screw 37 is provided on a side surface of the tilting table 35 to fix the tilting table 35 in a state where the tilt adjustment is performed.

Here, the base 25 of the support member 21
Is fixedly provided on the tilting table 35. Then, when the ultrasonic probe 7 is attached to a predetermined position of the positioning arm 26 of the support member 21 and the mounting member 24 is set to the test position, the transmitting / receiving surface 1a of the ultrasonic transducer 1 provided on the ultrasonic probe 7 The center is located on the extension of the rotation center of the turntable 30, and the extension of the rotation center coincides with the y-axis set on the transmission plane EP shown in FIG. Further, the center of the arc of the slide surface 35a of the tilting table 35 is set to coincide with the center of the transmission / reception surface 1a of the ultrasonic transducer 1, that is, the transmission center position O of the transmission surface EP in FIG.
Thereby, the adjustment axis at the time of angle adjustment by the θ stage 28 matches the y axis at the transmission center position O, and the adjustment axis at the time of angle adjustment by the tilt stage 33 matches the x axis of the transmission center position O. ing.

Therefore, when the rotary table 30 is rotated, the angle of the transmission surface EP is adjusted around the y-axis, and the sound axis S
A is displaced so as to swing right and left. When the tilting table 35 is tilted, the angle of the transmission surface EP is adjusted around the x-axis, and as a result, the sound axis SA swings up and down. As a result, by appropriately operating the θ stage 28 and the tilt stage 33, the sound axis S
A can be aligned so as to be directed in a direction exactly perpendicular to the scanning plane RP of the hydrophone 11. In addition, the center position of the transmitting / receiving surface 1a of the ultrasonic transducer 1 is fixedly held without misalignment during alignment.

With such a configuration, the ultrasonic probe 7 is provided on the supporting member 2 provided on the biaxial angle adjusting means 20.
In a state where the ultrasonic transducer 1 of the ultrasonic probe 7 transmits ultrasonic waves while the mounting member 24 is placed at the test position while the ultrasonic transducer 1 is attached to the predetermined position, By scanning the hydrophone 11 arranged at a position separated by a distance in the range set as the scanning plane RP, it is possible to obtain the entire image of the sound field including the sound pressure distribution in the cross section of the ultrasonic beam at the position.

In performing the measurement, first, when the ultrasonic probe 7 is mounted on the positioning arm 26, the sound axis SA of the ultrasonic transducer 1 is set to be exactly perpendicular to the scanning plane RP of the hydrophone 11. It is necessary to adjust the angle. For this purpose, the Z-axis robot 14 is operated to place the hydrophone 11 at a position at a predetermined distance from the ultrasonic probe 7. In this state, an ultrasonic beam is emitted from the ultrasonic transducer 1 and received by the hydrophone 11, and the Y-axis scanning unit 13Y and the X-axis scanning unit 13X constituting the scanning unit 13 are operated to operate the hydrophone 11 Is scanned along a predetermined plane. As a result, a sound pressure distribution of the ultrasonic wave on the plane (first scanning plane) is obtained. Next, by operating the Z-axis robot 14 to change the distance of the hydrophone 11 with respect to the ultrasonic transducer 1 and receiving the ultrasonic waves from the ultrasonic transducer 1 while scanning the hydrophone 11 similarly, The sound pressure distribution of the ultrasonic wave on the second scanning plane is obtained.

The first scanning plane obtained as described above and the second scanning plane
The position of each sound pressure peak is detected from the sound pressure distribution with the scan surface. Since the position of this sound pressure peak can be estimated to be a position on the sound axis SA in each cross section, if there is a shift in the position of the sound pressure peak between the second scanning surface and the second scanning surface, the scanning will be performed. It turns out that the plane is not in a state of being orthogonal to the sound axis SA exactly. Moreover, the inclination angles of the sound axis SA in the x-axis direction and the y-axis direction can be obtained from the positions of the sound pressure peaks on the first and second scanning planes and the distance between the sound pressure peaks. Therefore, from the result of this operation,
Feed screw 31 of θ stage 28 and tilt stage 33
By appropriately adjusting the feed screw 36, the ultrasonic transducer 1 and the hydrophone 11 can be aligned. When the alignment is performed, the rotary table 30 and the tilt table 3 are tightened by tightening the stopper screws 32 and 37, respectively.
5 is fixed.

Thus, the hydrophone 11 is arranged at a position separated from the ultrasonic transducer 1 by a predetermined distance. The positional relationship between the ultrasonic transducer 1 and the hydrophone 11 is at least the position of the far field FS. In this state, by transmitting an ultrasonic pulse from the ultrasonic transducer 1 and scanning the hydrophone 11, information on a sound field pattern including a sound field section at the position and a sound pressure distribution in the sound field section is obtained. I do. Based on this sound field pattern, the characteristics of the ultrasonic transducer 1, that is, the focal length, the beam diameter at the focal position, the sound pressure peak, and the like can be measured. As a result, by evaluating whether or not these are within an appropriate range, the ultrasonic transducer 1 is evaluated.
You can check the quality.

In particular, the Z-axis robot 14 is driven to sequentially obtain sound field patterns at respective positions while moving the hydrophone 11 away from the position close to the ultrasonic transducer 1 at predetermined pitch intervals. If the sound field pattern is subjected to three-dimensional processing, the entire image of the sound field of the ultrasonic transducer 1 can be grasped. From the overall image of the sound field, we can see all the characteristics of the ultrasonic beam, that is, the depth of the ultrasonic wave, the effective beam diameter, the data on the beam diameter at the focal length and focal position and its sound pressure, and the state of the side lobe Etc. can be accurately measured. Therefore, extremely useful data for confirming and evaluating the characteristics of the ultrasonic transducer 1 can be obtained.

In the above-described embodiment, the characteristic test is performed with the ultrasonic transducer incorporated in the medical ultrasonic probe. However, the ultrasonic transducer incorporated in another ultrasonic probe or the like may be used. Needless to say, a characteristic test or the like using only the ultrasonic transducer can be performed. Although the hydrophone is used as the target member, an element or the like that converts a received sound pressure signal into an electric signal or other signals can be used. In addition, a mirror-finished reflecting member that reflects ultrasonic waves can be used as the target member. In this case, ultrasonic waves transmitted from the ultrasonic transducer are reflected by the reflecting member, and the reflected echo is reflected by the ultrasonic transducer. Will be received. Furthermore, the support member for supporting the ultrasonic probe is provided on the tilt stage, and the θ stage is provided on the mounting member side. However, these two stages may be provided in reverse.
Further, the θ stage and the tilt stage may be provided on either the ultrasonic transducer side or the target member side, and it is also possible to provide the θ stage on one side and the tilt stage on the other side. Further, the detection of the positional deviation in performing the alignment between the ultrasonic transducer and the target member is not necessarily limited to the above-described one. For example, when the cross section of the ultrasonic beam is circular, a certain position is detected. It is also possible to detect the direction and the amount of the shift from the shape of the sound field pattern at step (1).

[0026]

As described above, the present invention is constructed as described above. In performing the characteristic test of the ultrasonic transducer, the relative position between the ultrasonic transducer and the target member of the ultrasonic beam transmitted from the ultrasonic transducer is determined. This has the effect that the positional relationship can be easily and accurately adjusted.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an ultrasonic transducer and an ultrasonic beam emitted from the ultrasonic transducer.

FIG. 2 is an external view of a main part showing an example of an ultrasonic probe to which an ultrasonic transducer is mounted.

FIG. 3 is a schematic configuration diagram of an ultrasonic transducer characteristic testing apparatus showing an embodiment of the present invention.

FIG. 4 is a diagram illustrating the principle of alignment between an ultrasonic transducer and a target member.

FIG. 5 is an explanatory diagram of a configuration of an angle adjusting unit of the ultrasonic transducer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ultrasonic transducer 1a Transmission / reception surface 7 Ultrasonic probe 10 Test tank 11 Hydrophone 12 Receiver 13 Scanning means 14 Z-axis robot 15 Support arm 20 Angle adjusting means 21 Support member 24 Mounting member 26 Positioning arm 28 θ stage 29 Fixing table 30 Rotary table 31 Feed screw 33 Tilt stage 34 Fixed table 35 Tilt table 36 Feed screw

Claims (2)

[Claims] In order to perform a characteristic test of an ultrasonic transducer, a target member for receiving or reflecting ultrasonic waves is installed in a test tank containing an ultrasonic transmission medium, and an ultrasonic beam is transmitted from the ultrasonic transducer. In the irradiation to the target member, a support member that supports at least one of the ultrasonic transducer and the target member is provided in connection with angle adjusting means, and the angle adjusting means includes the ultrasonic transducer or The target member is to be rotated about two orthogonal axes passing substantially through the central position of transmission / reception or reflection of the target member. The support member extends in one axial direction of the two orthogonal axes and extends around the axis. To rotate around the other of the two orthogonal axes, to rotate around the center position, Serial property testing apparatus of the ultrasonic transducer, characterized in that is constituted by the support member and tilt stage for circular motion. 2. An ultrasonic probe incorporating the ultrasonic transducer is detachably mounted on the support member provided on the angle adjusting means, and the target member transmits an ultrasonic signal from the ultrasonic transducer. It is composed of a receiving hydrophone and is attached to a scanning means for scanning the hydrophone on a substantially vertical plane, and the scanning means is attached to an interval adjusting means for bringing the hydrophone close to and away from the ultrasonic probe. 2. The ultrasonic transducer characteristic test apparatus according to claim 1, wherein said ultrasonic transducer has a structure.