JP3032439B2 - Ultrasonic transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to an ultrasonic wave transmitting / receiving apparatus, and in particular,
The present invention relates to an ultrasonic transmission / reception device with a variable focus position that enables highly accurate dynamics focus measurement, multi-stage focus measurement, and the like with a simple configuration.

[0002]

2. Description of the Related Art A large number of ultrasonic transducers are arranged in an arc or an array, and an electronic device for measuring the intensity of an ultrasonic wave with respect to a focal position formed by adjusting the transmission / reception timing of each ultrasonic pulse. A focus technique is known, and a technique capable of performing high-accuracy measurement of a target search area 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 vibrator 51... Has its output connected to an adder 53 via a delay circuit 52 whose set time can be changed. When the ultrasonic pulse is emitted, the ultrasonic pulse is reflected and dispersed by the propagation material, and the ultrasonic pulse reflected at the focal position 54 is transmitted to each of the transducers 51.
Are received at the same time 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 focal position and measure the reflected ultrasonic intensity distribution in the target search area.

[0004] In the above-mentioned electronic focus, ultrasonic pulses are respectively emitted for each focus position set in stages,
There is a method using multi-step focus for exploring a target area based on measurement values obtained in a stepwise manner. In addition, a method such as dynamic focus for changing a focus position during reception of an ultrasonic pulse is generally used. Methods for changing the delay amount include a method of sequentially switching with an analog switch (Japanese Utility Model Application Laid-Open No. 5-622121), a method of controlling the processing timing of memory data (Japanese Utility Model Application Laid-Open No. 5-63509), and a method using a variable capacitance diode and a coil. (Japanese Patent Laid-Open No. Hei 5-235696), a method of changing a delay in an intermediate frequency band by a local oscillator via a variable phase shifter and a mixer circuit (Japanese Patent Laid-Open No. 5-22)
No. 3793).

[0005]

However, these electronic focuses require a large number of processing circuits for each channel for handling a small signal of each of the divided transducers, and a focus position caused by the accuracy of setting the delay time. In addition to the difficulty of improving the measurement accuracy due to the variation in measurement, the problem of low frame rate in multi-stage focus, the discontinuity of analog switch switching and the countermeasures against switching noise, the complicated circuit configuration for digital processing of memory data and the addition signal Digital processing before logarithmic amplification causes problems such as loss of minute level signal, distortion of signal waveform due to impedance change of variable capacitance delay line, and limit of delay amount corresponding to phase change of local oscillator type. The present invention provides a high-precision dynamics focus 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]

Means for Solving the Problems To solve the above problems, an ultrasonic wave according to a supplied electric signal is transmitted from a transmitting and receiving surface, and an ultrasonic wave received by the transmitting and receiving surface is converted into the ultrasonic wave. Arc of the transmitting and receiving wave surface for converting into a corresponding electric signal
In an ultrasonic wave transmitting and receiving apparatus having an ultrasonic transducer whose center is the focal point of an ultrasonic signal, the ultrasonic transducer is curved.
Electrodes are attached to both sides of a flat plate-shaped flexible piezoelectric member,
One of the ultrasonic transducers that is opposed to each other to support both ends.
The ultrasonic transducer is deformed by a pair of bimorph piezoelectric elements
Moving the focal position by changing the curvature of the wave transmitting and receiving surface.
You .

Further, the converting ultrasonic waves according to the supplied electric signal while transmitting the transmitting and receiving surface, the ultrasonic wave reception in the transmitting and receiving surface into an electric signal corresponding to the ultrasonic
In an ultrasonic wave transmitting / receiving apparatus having an ultrasonic vibrator having an arc center of a wave transmitting / receiving surface as a focal point of an ultrasonic signal, the ultrasonic vibration
The moving element is electrically connected to both sides of a flexible piezoelectric member formed in a substantially hemispherical shell shape.
The poles are adhered, and the adherence is formed on the convex surface of the ultrasonic vibrator.
The transmitting and receiving surface area is increased by the unimorph piezoelectric element
The focal position by changing the curvature of the transmitting and receiving wave surface.
You .

[0008]

A pair of bimoles arranged opposite to each other to support both ends of an ultrasonic transducer formed in a flat plate having a curved transmitting and receiving surface.
The piezoelectric element deforms the ultrasonic vibrator
Since the curvature of the transmitting / receiving surface changes and the center of the arc of the transmitting / receiving surface moves, the focal point of the ultrasonic signal also moves.

[0009] An ultrasonic vibration having a transmission / reception surface formed in a substantially hemispherical shell shape.
The unimorph piezoelectric element formed on the convex surface of the rotor
By increasing or decreasing the area of the wavefront, the curvature of the wavefront
Changes, and the center of the arc of the transmitting and receiving
The focus of the issue will also move .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a functional block diagram of an ultrasonic measuring apparatus provided with the ultrasonic transmitting / receiving apparatus of the present invention, FIG. 2 is a perspective view of the ultrasonic transmitting / receiving apparatus according to the first embodiment of the present invention, and FIG. FIG.

The ultrasonic wave transmitting / receiving apparatus comprises an ultrasonic transducer 1 and a focus moving means 4 for changing a focal position 3 of the ultrasonic transducer 1, and responds to a voltage or current supplied from a focal position control unit 6. The focal position 3 is linearly changed on a line A indicated by a two-dot chain line in FIG. The transmitting and receiving surface 2 of the ultrasonic transducer 1 is formed in a concave shape having an arc-shaped cross section, for example, a curved flat plate or a hemispherical body having a spherical concave surface, and the center of the arc is set as an acoustic focus. The ultrasonic transducer 1 concentrates the ultrasonic signal emitted from the wave transmitting / receiving surface 2 on the focal position 3 based on the electric signal supplied from the transmitting / receiving section 5 and reflects the ultrasonic signal reflected from the focal position 3 or the vicinity thereof. And sends an electric signal based on the ultrasonic signal to the transmitting / receiving unit 5.

Specifically, as shown in FIG. 2, both surfaces of a high-molecular piezoelectric material 7a such as PVDF (polyvinylidene fluoride), which is a plate-like flexible member, are plastically worked into a substantially half-cylindrical shape. Electrode plates 8, 8 made of a metal material are adhered and formed to form an ultrasonic vibrator 7, and the concave side is the wave transmitting / receiving surface 2.
Here, the radius of curvature of the entire ultrasonic vibrator 7 can be changed by the elasticity of the electrode plates 8 and 8 and the ultrasonic vibrator 7. On a frame 9 made of a highly rigid material, bimorph piezoelectric elements 10 which are bent and displaced in accordance with a supplied voltage are arranged to face each other.
One end of them is fixed. The two free ends of the bimorph piezoelectric element 10 are configured to be separated or approach each other by the bending displacement, and by holding both ends of the ultrasonic vibrator 7 in an arch shape between the free ends, It constitutes a focus moving means.

[0013] In the ultrasonic wave transmitting and receiving apparatus thus configured, as shown in FIG.
When the ultrasonic transducers 10 are displaced so as to approach each other in accordance with the action voltage, the ultrasonic vibrator 7 including the electrodes 8 and 8 bends toward the frame 9 in accordance with the displacement, whereby the radius of curvature of the transmitting and receiving surface 2 is changed. Decreases, and the center of curvature, that is, the focal position 3 moves to the frame 9 side. Next, when the above-mentioned working voltage is reduced, the bimorph piezoelectric elements 10 and 10 return in the directions away from each other, and the ultrasonic vibrator 7 makes the electrode plates 8 and 8
Due to the resilience of the frame 9, it returns in the direction away from the frame 9, whereby the radius of curvature of the wave transmitting / receiving surface 2 increases, and the center of curvature, that is, the focal position moves in the direction away from the frame 9. That is, the focal position is linearly changed from the shallowest focal position 3a to the deepest focal position 3 in accordance with the voltage supplied to the bimorph piezoelectric elements 10 and 10 from the focal position control unit (not shown). Change.

Incidentally, the ultrasonic vibrator 7 having the above function
The procedure of the receiving dynamic focus operation is as follows. First, after applying a voltage to the bimorph piezoelectric elements 10 and 10, the ultrasonic vibrator 7 is adjusted to a focal position suitable for transmitting the ultrasonic pulse, and then the ultrasonic pulse is transmitted. Reception is performed by the focus moving means while changing from the shallowest position 3a to the deepest position 3 in accordance with the arrival time of the reflected signal.

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

FIG. 4 is a sectional view of an ultrasonic wave transmitting / receiving apparatus according to a second embodiment of the present invention. A high-molecular piezoelectric material such as PVDF (polyvinylidene fluoride) as a flexible member is formed in a concave shape having an arcuate cross section, for example, in a substantially hemispherical shell shape, and electrodes (not shown) are formed on the inner and outer surfaces thereof. Zu). The ultrasonic transducer 11 is configured as described above, and the inner surface of the concave shape is the wave transmitting / receiving surface 2 for transmitting and receiving the ultrasonic wave. By forming the transmitting / receiving surface 2 in a spherical shape, when an ultrasonic wave is emitted from the transmitting / receiving surface 2, the center of a 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 vibrator 11 to increase the rigidity of a substantially U-shaped cross section that forms a bottomed cylinder. The ultrasonic vibrator 11 is mounted inside the open end of the frame 15 so that the wave transmitting / receiving surface 2 faces outward.

The ultrasonic vibrator 11 of the ultrasonic wave transmitting / receiving apparatus having the above-described structure is configured such that when the unimorph piezoelectric element 13 as the focal point moving means increases or decreases the area of the spherical surface due to the applied voltage, the frame 15 ends up. As a result, the area of the wave transmitting / receiving surface 2 of the ultrasonic transducer 11 whose outer peripheral end is fixed increases / decreases, so that its curvature changes, and the focal position 3 of the wave transmitting / receiving surface 2 moves. That is, the focal point 3 of the ultrasonic wave transmitting / receiving device linearly moves between a position close to the wave transmitting / receiving surface 2 and a position away from the wave transmitting / receiving surface 2 in accordance with an output voltage of a focal position control means (not shown) for controlling the unimorph piezoelectric element 13. Change.

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

The peripheral edge of the backing material 18 of the ultrasonic vibrator 16 is connected to the frame 2 via an edge 19 made of a flexible member.
And a magnetic circuit comprising 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, that is, in a circular hole of the yoke plate 23 connected to the yoke 22. The pole piece 24 on the magnet 21 side is arranged concentrically with a gap.

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

In the ultrasonic wave transmitting / receiving apparatus thus constructed, the ultrasonic vibrator 16 controls the magnetic flux density in the gap between the yoke plate 23 and the pole piece 24 and the current supplied to the coil 25 from the focus position controller 6. And the focal position 3 can be moved back and forth. Further, according to the third embodiment, the transmitting / receiving wave surface 2 of the ultrasonic vibrator 16 is used.
By providing the focus position moving means which does not affect the shape of the lens, the variable focal length can be increased as compared with the first and second embodiments. Further, when the ultrasonic vibrator 16 is formed of a ceramic piezoelectric material, the electroacoustic sensitivity or acoustoelectric sensitivity of the ceramic piezoelectric member is higher than that of the polymer piezoelectric material. Thus, an ultrasonic transmission / reception device with high sensitivity can be realized. Needless to say, a magnetostrictive material or an electrostrictive material can be used as the ultrasonic vibrator 16.

In the third embodiment, a moving coil type electromechanical transducer is used as the focal point moving means for moving the ultrasonic vibrator 16 forward and backward. However, the present invention is not limited to this. Even if a transducer, for example, a piezoelectric actuator or an electromagnetic transducer is used, the same operation and effect as those of the third embodiment are exhibited.

In place of the two bimorph piezoelectric elements 10 in the first embodiment, electromechanical transducers including the above-described moving coil type are arranged facing each other, and both ends of the ultrasonic vibrator 7 are electrically connected. The same operation and effect as those of the first embodiment can be obtained even if the pressing is performed by the mechanical force corresponding to the signal.

[0024]

As described above, according to the first aspect of the present invention,
According to the present invention, a pair of bimorphs which are formed so that the transmitting and receiving surfaces of an ultrasonic vibrator are formed in a curved flat plate , the center of the arc of which is the focal point of the ultrasonic signal, and which is opposed to support both ends of the ultrasonic vibrator.
The ultrasonic transducer is deformed by the piezoelectric element,
The focus position is moved by changing the curvature of the ultrasonic wave, so it is possible to realize an ultrasonic transducer that can change the focus with high accuracy with a simple configuration, and it is possible to perform reflected ultrasonic measurement such as dynamics focus measurement, multi-stage focus measurement, etc. Become.

According to the second aspect of the present invention, a supersonic
The transmitting and receiving surface of the wave oscillator is formed in a substantially hemispherical shell shape and the arc
The heart is the focal point of the ultrasonic signal and is attached to the convex surface of the ultrasonic transducer
Increases the area of the transmitting and receiving surface by the formed unimorph piezoelectric element
Moving the focal position by changing the curvature of the transmitting and receiving surface.
A super sound that can change the focus with high accuracy with a simple configuration
Wave transmission / reception device can be realized,
Measurement, multi-focus measurement, etc.
You .

[Brief description of the drawings]

FIG. 1 is a functional configuration diagram of an ultrasonic measurement device including an ultrasonic transmission / reception device of the present invention.

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

FIG. 3 is a diagram for explaining the operation 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 apparatus according to a third embodiment of the present invention.

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic transducer, 2 ... Transmitting / receiving surface, 3 ... Focus, 4 ... Focus moving means, 5 ... Transmitter / receiver, 6 ... Focus position controller, 7 ... Ultrasonic transducer, 8 ... Electrode, 9 ... Frame, 10 ... bimorph piezoelectric element (focal point moving means), 11 ° ultrasonic vibrator, 1
3: Unimorph vibrator (focus moving means), 15: frame, 16: ultrasonic vibrator, 18: backing material, 19:
Edge, 20: frame, 21: magnet, 22: yoke, 23: yoke plate, 24: pole piece, 2
5: coil (focal point moving means), A: focal point moving path.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04R 17/00 330 G01B 17/00 G01N 29/24 G01S 7/521

Claims (2)

(57) [Claims] 1. A well as transmit the ultrasonic waves according to the supplied electric signal from the transmitting and receiving surface, the transmission and reception of converting the ultrasonic wave reception in the transmitting and receiving surface into an electric signal corresponding to the ultrasonic
In an ultrasonic wave transmitting / receiving apparatus having an ultrasonic vibrator having an arc center of a wavefront as a focal point of an ultrasonic signal, the ultrasonic vibrator
Has electrodes on both sides of a curved plate-shaped flexible piezoelectric member.
Facing each other to support both ends of the ultrasonic vibrator.
The ultrasonic vibration is caused by a pair of bimorph piezoelectric elements arranged.
Deform the rotor and change the curvature of the transmitting and receiving wave surface to change the focal position.
An ultrasonic wave transmitting / receiving apparatus characterized by moving an object. With wherein to transmit the ultrasonic waves according to the supplied electric signal from the transmitting and receiving surface, the transmission and reception of converting the ultrasonic wave reception in the transmitting and receiving surface into an electric signal corresponding to the ultrasonic
In an ultrasonic wave transmitting / receiving apparatus having an ultrasonic vibrator having an arc center of a wavefront as a focal point of an ultrasonic signal, the ultrasonic vibrator
Has electrodes on both sides of a flexible piezoelectric member formed in a substantially hemispherical shell shape.
It was adhered and formed on the convex surface of the ultrasonic vibrator.
Increase / decrease the area of the transmitting / receiving wave surface with a unimorph piezoelectric element
An ultrasonic wave transmitting / receiving apparatus , wherein a focal position is moved by changing a curvature of the wave transmitting / receiving surface.