JPH08154298A - Ultrasonic wave transmitter-receiver - Google Patents

Abstract

PURPOSE: To obtain an ultrasonic wave transmitter-receiver attaining reception dynamic focus measurement with a simple configuration and high accuracy. CONSTITUTION: A transmission reception wavefront 2 of an ultrasonic wave vibrator 1 is formed curved in a nearly half-cut cylinder and a cylinder axial line is used for a focus of an ultrasonic wave signal, a focus shift means 4 is provided and the ultrasonic wave management device is made up of a signal processing section 5 and a focal position control section 6 in addition to the means 4. Elastic electrodes 8, 8 are adhered to both sides of the ultrasonic wave vibrator 7 and the recessed side is used for the transmission reception wavefront 2. A frame 9 fixes a bimorph piezoelectric element 10 and both ends of the ultrasonic wave vibrator 7 are supported in an arch shape to form the focus shift means.

Description

Detailed Description of the Invention

The present invention relates to an ultrasonic wave transmitting / receiving device, and in particular,
The present invention relates to an ultrasonic wave transmitter / receiver capable of variable focus position that enables highly accurate dynamic focus measurement, multi-stage focus measurement, and the like with a simple configuration.

[0002]

2. Description of the Related Art An electronic device for measuring ultrasonic intensity related to a focal position formed by arranging a large number of ultrasonic transducers in an arc shape or an array shape and adjusting the transmission / reception timing of each ultrasonic pulse. A focus technique is known, and a technique capable of performing highly accurate measurement on a target search region by moving the focus position is used in an ultrasonic measurement device or the like.

FIG. 6 is a diagram showing the principle of electronic focusing. Each transducer 51 ... Connects its output to an adder 53 via a delay circuit 52 whose setting time can be changed. When the ultrasonic pulse is emitted, it is reflected and dispersed by the propagating substance, and the ultrasonic pulse reflected at the focus position 54 is transferred to each transducer 51 ...
The received signals at the time of arriving at are simultaneously added by passing through the delay circuit 52, and a predetermined resolution is obtained near the focal position. By changing the setting of each delay circuit 52, it is possible to change the focus position and measure the reflected ultrasonic wave intensity distribution for the target search area.

For the electronic focus, ultrasonic pulses are emitted for each focus position set in stages,
There is a method by multi-step focus to search the target area by the measurement value obtained stepwise, in addition, a method such as dynamic focus that changes the focus position during the reception of the ultrasonic pulse is generally used. As a method of changing the delay amount, a method of sequentially switching by an analog switch (Japanese Utility Model Laid-Open No. 5-62221), a method of controlling the processing timing of memory data (Japanese Utility Model Laid-Open No. 5-63509), a variable capacitance diode and a coil are used. Method (JP-A-5-235696), a method of changing delay in an intermediate frequency band by a local oscillator through a variable phase shifter and a mixer circuit (JP-A-5-22).
3793).

[0005]

However, these electronic focuses require a large number of processing circuits for each channel for handling the minute signals of the divided oscillators, and the focus position caused by the accuracy of setting the delay time. It is difficult to improve the measurement accuracy due to the variation of the multi-focus, low frame rate problem of multi-stage focus, discontinuity of analog switch switching and switching noise countermeasures, complicated circuit configuration for digital processing of memory data and addition signal Since there are problems such as loss of minute level signal due to digital processing before logarithmic amplification, distortion of signal waveform due to impedance change of variable capacitance delay line, limit of delay amount corresponding to phase change of local oscillator type, etc. The present invention provides highly accurate dynamics focus measurement and multi-stage measurement with a simple configuration for a target search area. And to obtain a focal position varying possible ultrasonic transmitter device capable of Okasu measurement and the like.

[0006]

In order to solve the above-mentioned problems, an ultrasonic wave corresponding to the supplied electric signal is transmitted from a transmitting / receiving surface, and the ultrasonic wave received by the transmitting / receiving surface is converted into the ultrasonic wave. In an ultrasonic wave transmitting / receiving apparatus having an ultrasonic transducer for converting into an electric signal according to the above, the transmitting / receiving surface of the ultrasonic transducer is formed in a concave shape having an arc-shaped cross section, and the center of the arc is made the focus of the ultrasonic signal. A focus moving means for moving the focus position is provided.

The ultrasonic transducer is formed by a plate-shaped flexible piezoelectric member so as to be deformable, and the flexible piezoelectric member is provided with a forcible deformation mechanism for changing its curvature to move the focal point. It is preferable that the means is used as a means, and a focus moving means is provided by providing an advancing / retreating mechanism that supports the ultrasonic transducer so that the ultrasonic transducer can advance and retreat, and that advances and retracts the position of the ultrasonic transducer.

[0008]

A simple structure is provided by forming the transmitting / receiving surface of the ultrasonic transducer into a concave shape having an arcuate cross section, using the center of the arc as the focal point of the ultrasonic wave signal, and providing the focal point moving means for moving the focal point position. The focus of the ultrasonic transducer can be moved by.

When the ultrasonic transducer is a plate-shaped flexible piezoelectric member and its curvature is changed by a forced deformation mechanism, the center point of the arc of the wave transmitting / receiving surface of the ultrasonic transducer, that is, The focal point of the ultrasonic signal moves, and when an advance / retreat mechanism is provided so that the ultrasonic transducer can move forward / backward, the focal point of the ultrasonic signal also moves due to the forward / backward movement of the ultrasonic transducer itself.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a functional configuration diagram of an ultrasonic wave measuring device equipped with the ultrasonic wave transmitting / receiving device of the present invention, FIG. 2 is a perspective view of the ultrasonic wave transmitting / receiving device according to the first embodiment of the present invention, and FIG. It is a figure.

The ultrasonic wave transmitting / receiving device is composed of an ultrasonic wave oscillator 1 and a focus moving means 4 for changing a focal position 3 of the ultrasonic wave oscillator 1. The ultrasonic wave transmitting / receiving device responds to a voltage or current supplied from a focal position control section 6. The focal point position 3 is linearly changed on the line A indicated by the chain double-dashed line in FIG. The wave transmission / reception surface 2 of the ultrasonic transducer 1 is formed in a concave shape having an arcuate cross section, for example, a curved flat plate or a hemispherical body having a spherical concave surface, and the arc center is an acoustic focus. The ultrasonic transducer 1 concentrates the ultrasonic signal emitted from the transmitting / receiving surface 2 at the focal position 3 based on the electric signal supplied from the transmitting / receiving unit 5, and reflects the ultrasonic signal reflected from the focal position 3 or its vicinity. Are collected and an electric signal based on this ultrasonic signal is sent to the transmitting / receiving unit 5.

More specifically, as shown in FIG. 2, both sides of a polymeric piezoelectric material 7a such as PVDF (polyvinylidene fluoride) forming a plate-shaped flexible member are plastically worked into a substantially half-cylindrical shape. The electrode plates 8 and 8 made of a metal material are adhered and formed to form the ultrasonic vibrator 7, and the concave surface side serves as the wave transmitting / receiving surface 2.
Here, the elasticity of the electrode plates 8 and 8 and the ultrasonic transducer 7 allows the radius of curvature of the entire ultrasonic transducer 7 to be changed. A bimorph piezoelectric element 10, which is bent and displaced according to a supplied voltage, is arranged to face a frame 9 made of a highly rigid material,
It fixes one end of them. Both free ends of the bimorph piezoelectric element 10 are configured so as to be separated from or approach each other by the bending displacement, and by holding both ends of the ultrasonic transducer 7 in an arch shape between the free ends, It constitutes a focal point moving means.

In the ultrasonic wave transmitting / receiving apparatus configured as described above, as shown in FIG. 3, the bimorph piezoelectric element 10,
When 10 is displaced so as to approach each other according to the applied voltage, the ultrasonic transducer 7 including the electrodes 8 and 8 is deflected toward the frame 9 side in accordance with the displacement, whereby the radius of curvature of the wave transmitting / receiving surface 2 is increased. Decreases, and the center of curvature, that is, the focus position 3 moves to the frame 9 side. Next, when the working voltage is reduced, the bimorph piezoelectric elements 10 and 10 return to the directions in which they are separated from each other, and the ultrasonic transducer 7 is connected to the electrode plates 8 and 8.
The elasticity returns to a direction away from the frame 9, which increases the radius of curvature of the wave transmitting / receiving surface 2, and the center of curvature, that is, the focus position moves in a direction away from the frame 9. That is, the focal point position is linearly linear from the shallowest focal point position 3a to the deepest focal point position 3 in accordance with the voltage supplied from the focal point position control unit (not shown) to the bimorph piezoelectric elements 10 and 10. Change.

Incidentally, the ultrasonic transducer 7 having the above-mentioned action.
The procedure of the receiving dynamic focus operation by the method is as follows. First, a voltage is applied to the bimorph piezoelectric elements 10 and 10 and the ultrasonic transducer 7 is adjusted to a focal position suitable for ultrasonic pulse transmission, and then ultrasonic pulse transmission is performed. Reception is performed while changing from the shallowest position 3a to the deepest position 3 according to the arrival time of the reflected signal by the focus moving means.

In the above ultrasonic measuring device, the ultrasonic pulse reflected at the focal position of the concave wave transmitting / receiving surface of the ultrasonic transducer reaches the wave transmitting / receiving surface of the ultrasonic transducer at the same time. The ultrasonic intensity can be measured by the received signal of the level, and the received dynamic focus measurement can be performed by changing the focal point position by the focal point moving means, and the highly accurate reflected ultrasonic wave can be measured by the simple configuration. It is also possible to perform multi-stage focus measurement by changing the focus position by the focus moving means each time the ultrasonic pulse is transmitted.

FIG. 4 is a sectional view of an ultrasonic wave transmitting / receiving apparatus according to the second embodiment of the present invention. A polymeric piezoelectric material such as PVDF (polyvinylidene fluoride) forming a flexible member is formed in a concave shape having an arc-shaped cross section, for example, in a substantially hemispherical shell shape, and electrodes (not shown) are formed on the inner and outer surfaces thereof. No)). The ultrasonic transducer 11 is configured in this way, and the concave inner surface is used as the wave transmitting / receiving surface 2 for transmitting / receiving ultrasonic waves. Since the transmitting / receiving surface 2 is formed in a spherical shape, when ultrasonic waves are emitted from the transmitting / receiving surface 2, the center of the sphere inscribed in the transmitting / receiving surface 2 becomes the focal point 3 of the ultrasonic wave. In addition to such a configuration, a unimorph piezoelectric element 13 whose area increases and decreases due to in-plane expansion and contraction is formed on the convex surface of the ultrasonic transducer 11 to increase the rigidity of a substantially U-shaped cross section forming a bottomed cylinder. The ultrasonic transducer 11 is attached inside the open end of the frame 15 so that the wave transmitting / receiving surface 2 faces outward.

In the ultrasonic transducer 11 of the ultrasonic wave transmitting / receiving apparatus having the above-described structure, when the unimorph piezoelectric element 13 which is the focus moving means increases or decreases the area of the spherical surface due to the acting voltage, the frame 15 is eventually obtained. As a result, the area of the wave transmission / reception surface 2 of the ultrasonic transducer 11 whose outer peripheral end is fixed increases or decreases, and therefore its curvature changes, and the focus position 3 of the wave transmission / reception surface 2 moves. That is, the focal point 3 of the ultrasonic wave transmitting / receiving device linearly extends from a position close to the wave transmitting / receiving surface 2 to a position away from the wave transmitting / receiving surface 2 according to an output voltage of a focus position control unit (not shown) that controls the unimorph piezoelectric element 13. Change.

FIG. 5 is a sectional view of an ultrasonic wave transmitting / receiving apparatus according to the third embodiment of the present invention. The ultrasonic oscillator 16 is formed of a piezoelectric material such as a polymer or ceramic in a concave shape having an arc-shaped cross section, and in the case of this embodiment, for example, is formed in a substantially hemispherical shape. Electrodes (not shown) on the concave and convex surfaces
The backing material 18 is laminated on the entire convex surface and the spherical surface is formed on the concave surface to form a wave transmitting / receiving surface 2 for transmitting / receiving ultrasonic waves. By forming the concave side into a spherical shape, when the ultrasonic wave signal is emitted from the wave transmitting / receiving surface 2, the center of the sphere becomes the focal point 3 of the ultrasonic wave signal.

The periphery of the backing material 18 of the ultrasonic transducer 16 is provided with a frame 2 via an edge 19 made of a flexible member.
A magnetic circuit composed of a magnet 21, a yoke 22, a yoke plate 23 and a pole piece 24 is formed on the back side of the frame 20 so as to be able to move back and forth, that is, inside a circular hole of the yoke plate 23 connected to the yoke 22. The pole piece 24 on the magnet 21 side is concentrically arranged with a gap.

A coil 25 attached to the ultrasonic transducer 16 is arranged in this gap, and the coil 25 is electrically connected to a focus position control section (not shown) capable of supplying current. Thus, in the ultrasonic wave transmitting / receiving device, a moving coil type focus position moving means is formed.

In the ultrasonic wave transmitting / receiving apparatus having the above-described structure, the ultrasonic transducer 16 has a magnetic flux density in the gap between the yoke plate 23 and the pole piece 24 and a current supplied from the focus position control unit 6 to the coil 25. The focus position 3 can be moved back and forth. Further, according to the third embodiment, the wave transmitting / receiving surface 2 of the ultrasonic transducer 16 is
By providing the focus position moving means that does not affect the shape, the variable focus distance can be increased as compared with the first and second embodiments. Further, when the ultrasonic transducer 16 is formed of a ceramic piezoelectric material, the electro-acoustic sensitivity or acousto-electric sensitivity of the ceramic piezoelectric member is higher than that of the polymer piezoelectric material, and therefore, compared with the case where it is formed of the polymer piezoelectric material. It is possible to realize a highly sensitive ultrasonic wave transmitting / receiving device. It goes without saying that a magnetostrictive material or an electrostrictive material can be used as the ultrasonic vibrator 16.

In the third embodiment, a moving coil type electromechanical converter is used as the focus moving means for moving the ultrasonic transducer 16 back and forth, but the present invention is not limited to this and various other electric machines are used. Even if a converter, for example, a piezoelectric actuator or an electromagnetic converter is used, the same effect as that of the third embodiment can be obtained.

Further, instead of the two bimorph piezoelectric elements 10 in the first embodiment, electromechanical transducers including the above moving coil type are arranged so as to face each other, and both ends of the ultrasonic transducer 7 are electrically connected. Even if it is pressed by the mechanical force according to the signal, the same effect as the first embodiment can be obtained.

[0024]

As described above, in the ultrasonic wave transmitting / receiving apparatus according to the present invention, the wave transmitting / receiving surface of the ultrasonic transducer is formed in a concave shape having an arcuate cross section, and the center of the arcuate is the focal point of the ultrasonic wave signal.
By providing the focal point moving means for moving the focal point position, it is possible to realize an ultrasonic wave transmitting / receiving device capable of changing the focal point with high accuracy by a simple configuration, and reflected ultrasonic wave measurement such as dynamics focus measurement and multi-stage focus measurement. Is possible.

When the ultrasonic transducer is a piezoelectric member having a plate-like flexibility and its curvature is changed by a forced deformation mechanism, the center of the arc of the wave transmitting / receiving surface of the piezoelectric ultrasonic transducer is forced by the forced deformation. That is, the focal point of the ultrasonic signal is moved, and when the ultrasonic transducer is allowed to move back and forth, and a forced forward / backward mechanism is provided, the ultrasonic transducer itself is moved forward and backward to move the focal point of the ultrasonic signal. Similarly, with a simple structure, it is possible to realize an ultrasonic wave transmitting / receiving device capable of varying the focus, which enables highly accurate reflected ultrasonic wave measurement.

[Brief description of drawings]

FIG. 1 is a functional configuration diagram of an ultrasonic measuring device including an ultrasonic wave transmitting / receiving device of the present invention.

FIG. 2 is a perspective view of the ultrasonic wave transmitting / receiving device according to the first embodiment of the present invention.

FIG. 3 is an operation explanatory view of the ultrasonic wave transmitting / receiving device.

FIG. 4 is a sectional view of an ultrasonic wave transmitting / receiving apparatus according to a second embodiment of the present invention.

FIG. 5 is a sectional view of an ultrasonic wave transmitting / receiving device according to a third embodiment of the present invention.

FIG. 6 is a conventional ultrasonic wave transmitting / receiving apparatus having a structure in which a focal point is electronically moved.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic transducer, 2 ... Transmission / reception surface, 3 ... Focus, 4 ... Focus moving means, 5 ... Transmitting / receiving section, 6 ... Focus position control section, 7 ... Ultrasonic transducer, 8 ... Electrode, 9 ... Frame, 10 ... Bimorph piezoelectric element (focus moving means), 11 ... Ultrasonic transducer, 1
3 ... Unimorph oscillator (focus moving means), 15 ... Frame, 16 ... Ultrasonic oscillator, 18 ... Backing material, 19 ...
Edge, 20 ... Frame, 21 ... Magnet, 22 ... Yoke, 23 ... Yoke plate, 24 ... Pole piece, 2
5 ... Coil (focus moving means), A ... Focus moving path.

Claims (3)

[Claims] 1. An ultrasonic transducer for transmitting an ultrasonic wave according to a supplied electric signal from a transmitting / receiving surface and converting the ultrasonic wave received on the transmitting / receiving surface into an electric signal according to the ultrasonic wave. In the ultrasonic wave transmitting / receiving apparatus having, a transmitting / receiving surface of the ultrasonic transducer is formed in a concave shape having an arc-shaped cross section, and the center of the arc is used as a focal point of an ultrasonic signal, and a focal point moving means for moving the focal point position is provided. An ultrasonic wave transmitting / receiving device characterized in that 2. The ultrasonic wave transmitting / receiving apparatus according to claim 1, wherein the ultrasonic vibrator is formed deformably by a plate-shaped flexible piezoelectric member, and the flexible piezoelectric element is used. An ultrasonic wave transmitting / receiving device, characterized in that the member is provided with a forcible deformation mechanism for changing its curvature, which is the focus moving means. 3. The ultrasonic wave transmitting / receiving apparatus according to claim 1, wherein the ultrasonic wave oscillator is supported so as to be able to move forward and backward, and an advance / retreat mechanism that moves the position of the ultrasonic wave oscillator forward and backward is provided. An ultrasonic wave transmitting / receiving device characterized in that it is used as a focus moving means.