[go: up one dir, main page]

EP0373603B1 - Ultrasonic probe - Google Patents

Ultrasonic probe Download PDF

Info

Publication number
EP0373603B1
EP0373603B1 EP19890122956 EP89122956A EP0373603B1 EP 0373603 B1 EP0373603 B1 EP 0373603B1 EP 19890122956 EP19890122956 EP 19890122956 EP 89122956 A EP89122956 A EP 89122956A EP 0373603 B1 EP0373603 B1 EP 0373603B1
Authority
EP
European Patent Office
Prior art keywords
ultrasonic probe
piezoelectric element
piezoelectric
elements
transducer elements
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19890122956
Other languages
German (de)
French (fr)
Other versions
EP0373603A2 (en
EP0373603A3 (en
Inventor
Hideyuki Tanaka
Koetsu Saito
Ikuo Sakai
Masami Kawabuchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Publication of EP0373603A2 publication Critical patent/EP0373603A2/en
Publication of EP0373603A3 publication Critical patent/EP0373603A3/en
Application granted granted Critical
Publication of EP0373603B1 publication Critical patent/EP0373603B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B06B1/0622—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements on one surface
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/18—Methods or devices for transmitting, conducting or directing sound
    • G10K11/26—Sound-focusing or directing, e.g. scanning
    • G10K11/32—Sound-focusing or directing, e.g. scanning characterised by the shape of the source

Definitions

  • This invention generally relates to an ultrasonic probe for an ultrasonic system, and specifically relates to an ultrasonic probe moved mechanically to generate a "B-mode" image of an examined object.
  • an ultrasonic probe is mechanically moved to generate a "B-mode" image of an examined object.
  • an ultrasonic probe includes a plurality of piezoelectric elements extending concentrically.
  • the elements have respective surfaces via which ultrasonic wave is transmitted and received.
  • the surfaces of the elements are concave and have predetermined radii of curvature respectively.
  • the radii of curvature increase as the elements are farther from an innermost place and closer to an outermost place.
  • the array consists of three regions having different focal points on a common array axis, whereby each region has several transducer elements, whereby steps in the beam width exist.
  • the object of the present invention is to provide an ultrasonic probe allowing focusing with reduced beam diameter, without steps in the beam width.
  • Fig. 1(a) is a plan view of a piezoelectric element array in an ultrasonic probe according to an embodiment of this invention.
  • Fig. 1(b) is a sectional view of the piezoelectric element array which is taken along the line L-L of Fig. 1(a).
  • Fig. 2 is a diagram showing results of a computer simulation of dynamic focusing in the ultrasonic probe of Figs. 1(a) and 1(b).
  • Fig. 3(a) is a plan view of a piezoelectric element array in a first example of a prior-art ultrasonic probe.
  • Fig. 3(b) is a sectional view of the piezoelectric element array of Fig. 3(a).
  • Fig. 4 is a plan view of a piezoelectric element array in a second example of the prior-art ultrasonic probe.
  • Fig. 5 is a diagram showing results of a computer simulation of dynamic focusing in the second example of the prior-art ultrasonic probe.
  • Fig. 6 is a diagram showing results of a computer simulation of dynamic focusing in a third example of the prior-art ultrasonic probe.
  • a first example of the prior-art ultrasonic probe includes a piezoelectric element array (a transducer element array) 51 which has a central disk piezoelectric element (a central disk transducer element) 52A and ring piezoelectric elements (ring transducer elements) 52B, 52C, 52D, and 52E concentrically extending around the central piezoelectric element 52A.
  • a pulse beam of ultrasonic wave is transmitted from and received by the piezoelectric element array 51.
  • the piezoelectric elements 52A-52E form a front surface 54 via which the ultrasonic wave beam is transmitted and received.
  • the transmission/reception surface 54 is concaved to structurally focus the transmitted and received ultrasonic wave beams.
  • the whole of the transmission/reception surface 54 is spherical with a predetermined common or uniform radius "r" of curvature.
  • the ultrasonic wave beam is also focused through signal processing called “electronic focusing".
  • the electronic focusing offers suitable delays to output signals from the respective piezoelectric elements and then combines the delayed signals.
  • Fig. 4 shows a second example of the prior-art ultrasonic probe which is basically similar to the prior-art ultrasonic probe of Figs. 3(a) and 3(b) except for design changes indicated hereinafter.
  • the prior-art ultrasonic probe of Fig. 4 includes a piezoelectric element array 51 of a six-segment type. Specifically, the piezoelectric element array 51 has a central disk piezoelectric element 52A and ring piezoelectric elements 52B, 52C, 52D, 52E, and 52F concentrically extending around the central piezoelectric element 52A.
  • the piezoelectric elements 52A-52F are separated by annular gaps 53.
  • the piezoelectric elements 52A-52F form a flat transmission/reception surface.
  • the areas of the respective piezoelectric elements 52A-52F over the transmission/reception surface are set approximately equal to each other.
  • the widths of the gaps 53 are set to 0. 2 mm.
  • the dimensions of the piezoelectric elements 52A-52F are chosen as follows: The outside diameter of the element 52A: 9.64 mm
  • the inside diameter of the element 52B 10.04 mm
  • the outside diameter of the element 52B 13.92 mm
  • the inside diameter of the element 52C 14.32 mm
  • the outside diameter of the element 52C 17.26 mm
  • the inside diameter of the element 52D 17.66 mm
  • the outside diameter of the element 52D 20.12 mm
  • the inside diameter of the element 52E 20.56 mm
  • the inside diameter of the element 52F 23.06 mm
  • the outside diameter of the element 52F 25.00 mm
  • Fig. 5 shows results of a computer simulation calculating conditions of dynamic focusing which occurred while the prior-art ultrasonic probe of Fig. 4 was receiving echo signals.
  • the dynamic focusing is explained in various published documents, for example, the Journal of the Acoustical Society of Japan Vol. 32, No. 6, Jun. 1976, pages 355-361.
  • the central frequency of the echo signals was set to 3.5 MHz
  • the pulse length of the ultrasonic wave beam was set equal to three times the wavelength of the central-frequency ultrasonic wave
  • the envelope of the pulses of the ultrasonic wave beam was of the half-sine shape or the half-sinusoidal form.
  • this computer simulation ignored a nonlinear effect on the pulse propagation in an ultrasonic wave transmission medium.
  • a beam width determined by -20 dB lines is relatively large and the degree of focusing is insufficient in an examined region of 50-70 mm although the ultrasonic wave beam is intended to be focused on an examined distance of 70 mm by electronic focusing using the two inner piezoelectric elements 52A and 52B. Furthermore, in an examined region of 0-50 mm, since only the central piezoelectric element 52A is used in electronic focusing, the degree of focusing tends to be insufficient.
  • a third example of the prior-art ultrasonic probe is similar to the prior-art ultrasonic probe of Figs. 4 and 5 except that the piezoelectric elements 52A-52F form a spherically concave transmission/reception surface having a predetermined common radius of curvature which equals 50 mm.
  • the concave design of the transmission/reception surface of the piezoelectric element array 51 functions to structurally focus the transmitted and received ultrasonic wave beams.
  • Fig. 6 shows results of a computer simulation calculating conditions of dynamic focusing which occurred while the third example of the prior-art ultrasonic probe was receiving echo signals. In the computer simulation related to Fig.
  • the central frequency of the echo signals was set to 3.5 MHz; the pulse length of the ultrasonic wave beam was set equal to three times the wavelength of the central-frequency ultrasonic wave; and the envelope of the pulses of the ultrasonic wave beam was of the half-sine shape or the half-sinusoidal form.
  • this computer simulation ignored a nonlinear effect on the pulse propagation in an ultrasonic wave transmission medium.
  • the examples of the prior-art ultrasonic probe can not have adequate characteristics of focusing of ultrasonic wave beams in both of a close examined region and a far examined region.
  • FIGs. 1(a) and 1(b) show a part of an ultrasonic probe according to an embodiment of this invention.
  • This embodiment is directed to an ultrasonic probe having a piezoelectric element array of a six-segment type.
  • the ultrasonic probe of Figs. 1(a) and 1(b) includes a piezoelectric element array (a transducer element array) 1 of a six-segment type.
  • the piezoelectric element array 1 has a central disk piezoelectric element (a central disk transducer element) 2A and ring piezoelectric elements (ring transducer elements) 2B, 2C, 2D, 2E, and 2F concentrically extending around the central piezoelectric element 2A.
  • the piezoelectric element array 1 is mechanically moved within liquid in a direction perpendicular to its axis by a known drive mechanism (not shown).
  • the piezoelectric elements 2A-2F are separated by annular gaps 3.
  • the piezoelectric element array 1 has a concave front surface 4 via which ultrasonic wave beams are transmitted and received.
  • the concave design of the transmission/reception surface 4 functions to structurally focus the ultrasonic wave beams.
  • front surfaces 4A, 4B, 4C, 4D, 4E, and 4F of the respective piezoelectric elements 2A, 2B, 2C, 2D, 2E, and 2F form the transmission/reception surface 4.
  • the surfaces 4A, 4B, 4C, 4D, 4E, and 4F are spherically concave and have predetermined different radii ra, rb, rc, rd, re, and rf of curvature respectively.
  • the radius of curvature of the transmission/reception surface of a piezoelectric element determines the structural focal point of the piezoelectric element.
  • the curvature radius ra of the central piezoelectric element 2A is the smallest.
  • the curvature radius rb of the piezoelectric element 2B is greater than the curvature radius ra of the central piezoelectric element 2A.
  • the curvature radius rc of the piezoelectric element 2C is greater than the curvature radius rb of the piezoelectric element 2B.
  • the curvature radius rd of the piezoelectric element 2D is greater than the curvature radius rc of the piezoelectric element 2C.
  • the curvature radius re of the piezoelectric element 2E is greater than the curvature radius rd of the piezoelectric element 2D.
  • the curvature radius rf of the piezoelectric element 2F is greater than the curvature radius re of the piezoelectric element 2E and is the greatest. In this way, inner piezoelectric elements have smaller radii of curvature or closer structural focal points, and outer piezoelectric elements have greater radii of curvature or farther structural focal points. In other words, the curvature radius of a piezoelectric element increases as the location of the piezoelectric element is closer to the outermost place.
  • the radii of curvature of the piezoelectric elements 2A-2F are chosen as follows: The curvature radius of the element 2A: 50 mm The curvature radius of the element 2B: 80 mm The curvature radius of the element 2C: 120 mm The curvature radius of the element 2D: 130 mm The curvature radius of the element 2E: 140 mm The curvature radius of the element 2F: 150 mm
  • the areas of the respective piezoelectric elements 2A-2F over the transmission/reception surface 4 are set approximately equal to each other.
  • the widths of the gaps 3 are set to 0. 2 mm.
  • the dimensions of the piezoelectric elements 2A-2F are chosen as follows: The outside diameter of the element 2A: 9.64 mm The inside diameter of the element 2B: 10.04 mm The outside diameter of the element 2B: 13.92 mm The inside diameter of the element 2C: 14.32 mm The outside diameter of the element 2C: 17.26 mm The inside diameter of the element 2D: 17.66 mm The outside diameter of the element 2D: 20.12 mm. The inside diameter of the element 2E: 20.56 mm The outside diameter of the element 2E: 22.66 mm The inside diameter of the element 2F: 23.06 mm The outside diameter of the element 2F: 25.00 mm
  • Fig. 2 shows results of a computer simulation calculating conditions of dynamic focusing which occurred while the ultrasonic probe of Figs 1(a) and 1(b) was receiving echo signals.
  • the dynamic focusing is explained in various published documents, for example, the Journal of the Acoustical Society of Japan Vol. 32, No. 6, Jun. 1976, pages 355-361.
  • the central frequency of the echo signals was set to 3.5 MHz;
  • the pulse length of the ultrasonic wave beam was set equal to three times the wavelength of the central-frequency ultrasonic wave; and the envelope of the pulses of the ultrasonic wave beam was of the half-sine shape or the half-sinusoidal form.
  • this computer simulation ignored a nonlinear effect on the pulse propagation in an ultrasonic wave transmission medium.
  • Fig. 2 It is seen from Fig. 2 that the characteristics of focusing are satisfactory in both of a close examined region and a far examined region.
  • the satisfactorily focusing results from the following facts.
  • dynamic focusing is effective since only inner piezoelectric elements are used in the dynamic focusing and the inner piezoelectric elements have closer structural focal points.
  • dynamic focusing is effective since all the piezoelectric elements 2A-2F are used in the dynamic focusing and many piezoelectric elements having far structural focal points are used in the dynamic focusing.
  • An ultrasonic probe includes a plurality of piezoelectric elements extending concentrically.
  • the elements have respective surfaces via which ultrasonic wave is transmitted and received.
  • the surfaces of the elements are concave and have predetermined radii of curvature respectively. The radii of curvature increase as the elements are farther from an innermost place and closer to an outermost place.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Mechanical Engineering (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Description

    BACKGROUND OF THE INVENTION
  • This invention generally relates to an ultrasonic probe for an ultrasonic system, and specifically relates to an ultrasonic probe moved mechanically to generate a "B-mode" image of an examined object.
  • In some ultrasonic systems, an ultrasonic probe is mechanically moved to generate a "B-mode" image of an examined object.
  • The Journal of the Acoustical Society of Japan Vol. 32, No. 6, Jun. 1976, pages 355-361 discloses such a ultrasonic probe. As will be explained later, the prior-art ultrasonic probe of this Journal has problems.
  • According to a prior art documen, US-A-4 276 779, an ultrasonic probe includes a plurality of piezoelectric elements extending concentrically. The elements have respective surfaces via which ultrasonic wave is transmitted and received. The surfaces of the elements are concave and have predetermined radii of curvature respectively. The radii of curvature increase as the elements are farther from an innermost place and closer to an outermost place. Thus, the array consists of three regions having different focal points on a common array axis, whereby each region has several transducer elements, whereby steps in the beam width exist.
  • The object of the present invention is to provide an ultrasonic probe allowing focusing with reduced beam diameter, without steps in the beam width.
  • The object is solved by the probe defined in independent claim 1.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • Fig. 1(a) is a plan view of a piezoelectric element array in an ultrasonic probe according to an embodiment of this invention.
  • Fig. 1(b) is a sectional view of the piezoelectric element array which is taken along the line L-L of Fig. 1(a).
  • Fig. 2 is a diagram showing results of a computer simulation of dynamic focusing in the ultrasonic probe of Figs. 1(a) and 1(b).
  • Fig. 3(a) is a plan view of a piezoelectric element array in a first example of a prior-art ultrasonic probe.
  • Fig. 3(b) is a sectional view of the piezoelectric element array of Fig. 3(a).
  • Fig. 4 is a plan view of a piezoelectric element array in a second example of the prior-art ultrasonic probe.
  • Fig. 5 is a diagram showing results of a computer simulation of dynamic focusing in the second example of the prior-art ultrasonic probe.
  • Fig. 6 is a diagram showing results of a computer simulation of dynamic focusing in a third example of the prior-art ultrasonic probe.
    • DESCRIPTION OF THE PREFERRED EMBODIMENT
  • Before a detailed description of this invention, the prior-art ultrasonic probe will be explained for a better understanding of this invention.
  • As shown in Figs 3(a) and 3(b), a first example of the prior-art ultrasonic probe includes a piezoelectric element array (a transducer element array) 51 which has a central disk piezoelectric element (a central disk transducer element) 52A and ring piezoelectric elements (ring transducer elements) 52B, 52C, 52D, and 52E concentrically extending around the central piezoelectric element 52A. A pulse beam of ultrasonic wave is transmitted from and received by the piezoelectric element array 51. The piezoelectric elements 52A-52E form a front surface 54 via which the ultrasonic wave beam is transmitted and received. The transmission/reception surface 54 is concaved to structurally focus the transmitted and received ultrasonic wave beams. The whole of the transmission/reception surface 54 is spherical with a predetermined common or uniform radius "r" of curvature. In general, the ultrasonic wave beam is also focused through signal processing called "electronic focusing". The electronic focusing offers suitable delays to output signals from the respective piezoelectric elements and then combines the delayed signals.
  • Fig. 4 shows a second example of the prior-art ultrasonic probe which is basically similar to the prior-art ultrasonic probe of Figs. 3(a) and 3(b) except for design changes indicated hereinafter. The prior-art ultrasonic probe of Fig. 4 includes a piezoelectric element array 51 of a six-segment type. Specifically, the piezoelectric element array 51 has a central disk piezoelectric element 52A and ring piezoelectric elements 52B, 52C, 52D, 52E, and 52F concentrically extending around the central piezoelectric element 52A. The piezoelectric elements 52A-52F are separated by annular gaps 53. The piezoelectric elements 52A-52F form a flat transmission/reception surface. The areas of the respective piezoelectric elements 52A-52F over the transmission/reception surface are set approximately equal to each other. The widths of the gaps 53 are set to 0. 2 mm. The dimensions of the piezoelectric elements 52A-52F are chosen as follows:
    The outside diameter of the element 52A: 9.64 mm
    The inside diameter of the element 52B: 10.04 mm
    The outside diameter of the element 52B: 13.92 mm
    The inside diameter of the element 52C: 14.32 mm
    The outside diameter of the element 52C: 17.26 mm
    The inside diameter of the element 52D: 17.66 mm
    The outside diameter of the element 52D: 20.12 mm
    The inside diameter of the element 52E: 20.56 mm
    The outside diameter of the element 52E: 22.66 mm
    The inside diameter of the element 52F: 23.06 mm
    The outside diameter of the element 52F: 25.00 mm
  • Fig. 5 shows results of a computer simulation calculating conditions of dynamic focusing which occurred while the prior-art ultrasonic probe of Fig. 4 was receiving echo signals. The dynamic focusing is explained in various published documents, for example, the Journal of the Acoustical Society of Japan Vol. 32, No. 6, Jun. 1976, pages 355-361. In the computer simulation related to Fig. 5: the central frequency of the echo signals was set to 3.5 MHz; the pulse length of the ultrasonic wave beam was set equal to three times the wavelength of the central-frequency ultrasonic wave; and the envelope of the pulses of the ultrasonic wave beam was of the half-sine shape or the half-sinusoidal form. In addition, this computer simulation ignored a nonlinear effect on the pulse propagation in an ultrasonic wave transmission medium.
  • It is seen from Fig. 5 that a beam width determined by -20 dB lines is relatively large and the degree of focusing is insufficient in an examined region of 50-70 mm although the ultrasonic wave beam is intended to be focused on an examined distance of 70 mm by electronic focusing using the two inner piezoelectric elements 52A and 52B. Furthermore, in an examined region of 0-50 mm, since only the central piezoelectric element 52A is used in electronic focusing, the degree of focusing tends to be insufficient.
  • A third example of the prior-art ultrasonic probe is similar to the prior-art ultrasonic probe of Figs. 4 and 5 except that the piezoelectric elements 52A-52F form a spherically concave transmission/reception surface having a predetermined common radius of curvature which equals 50 mm. The concave design of the transmission/reception surface of the piezoelectric element array 51 functions to structurally focus the transmitted and received ultrasonic wave beams. Fig. 6 shows results of a computer simulation calculating conditions of dynamic focusing which occurred while the third example of the prior-art ultrasonic probe was receiving echo signals. In the computer simulation related to Fig. 6: the central frequency of the echo signals was set to 3.5 MHz; the pulse length of the ultrasonic wave beam was set equal to three times the wavelength of the central-frequency ultrasonic wave; and the envelope of the pulses of the ultrasonic wave beam was of the half-sine shape or the half-sinusoidal form. In addition, this computer simulation ignored a nonlinear effect on the pulse propagation in an ultrasonic wave transmission medium.
  • It is seen from Fig. 6 that electronic focusing is essentially ineffective in a far examined region over 100 mm while the focusing is improved in a close examined region relative to the case of Fig. 5.
  • As understood from the previous description, the examples of the prior-art ultrasonic probe can not have adequate characteristics of focusing of ultrasonic wave beams in both of a close examined region and a far examined region.
  • This invention will now be explained in detail. Figs. 1(a) and 1(b) show a part of an ultrasonic probe according to an embodiment of this invention. This embodiment is directed to an ultrasonic probe having a piezoelectric element array of a six-segment type.
  • The ultrasonic probe of Figs. 1(a) and 1(b) includes a piezoelectric element array (a transducer element array) 1 of a six-segment type. Specifically, the piezoelectric element array 1 has a central disk piezoelectric element (a central disk transducer element) 2A and ring piezoelectric elements (ring transducer elements) 2B, 2C, 2D, 2E, and 2F concentrically extending around the central piezoelectric element 2A. During a scanning process, the piezoelectric element array 1 is mechanically moved within liquid in a direction perpendicular to its axis by a known drive mechanism (not shown). The piezoelectric elements 2A-2F are separated by annular gaps 3. The piezoelectric element array 1 has a concave front surface 4 via which ultrasonic wave beams are transmitted and received. The concave design of the transmission/reception surface 4 functions to structurally focus the ultrasonic wave beams.
  • Specifically, front surfaces 4A, 4B, 4C, 4D, 4E, and 4F of the respective piezoelectric elements 2A, 2B, 2C, 2D, 2E, and 2F form the transmission/reception surface 4. The surfaces 4A, 4B, 4C, 4D, 4E, and 4F are spherically concave and have predetermined different radii ra, rb, rc, rd, re, and rf of curvature respectively. In general, the radius of curvature of the transmission/reception surface of a piezoelectric element determines the structural focal point of the piezoelectric element. Specifically, as the radius of curvature of the transmission/reception surface of a piezoelectric element increases, the structural focal point of the piezoelectric element is farther. The curvature radius ra of the central piezoelectric element 2A is the smallest. The curvature radius rb of the piezoelectric element 2B is greater than the curvature radius ra of the central piezoelectric element 2A. The curvature radius rc of the piezoelectric element 2C is greater than the curvature radius rb of the piezoelectric element 2B. The curvature radius rd of the piezoelectric element 2D is greater than the curvature radius rc of the piezoelectric element 2C. The curvature radius re of the piezoelectric element 2E is greater than the curvature radius rd of the piezoelectric element 2D. The curvature radius rf of the piezoelectric element 2F is greater than the curvature radius re of the piezoelectric element 2E and is the greatest. In this way, inner piezoelectric elements have smaller radii of curvature or closer structural focal points, and outer piezoelectric elements have greater radii of curvature or farther structural focal points. In other words, the curvature radius of a piezoelectric element increases as the location of the piezoelectric element is closer to the outermost place. Specifically, the radii of curvature of the piezoelectric elements 2A-2F are chosen as follows:
    The curvature radius of the element 2A: 50 mm
    The curvature radius of the element 2B: 80 mm
    The curvature radius of the element 2C: 120 mm
    The curvature radius of the element 2D: 130 mm
    The curvature radius of the element 2E: 140 mm
    The curvature radius of the element 2F: 150 mm
  • The areas of the respective piezoelectric elements 2A-2F over the transmission/reception surface 4 are set approximately equal to each other. The widths of the gaps 3 are set to 0. 2 mm. The dimensions of the piezoelectric elements 2A-2F are chosen as follows:
    The outside diameter of the element 2A: 9.64 mm
    The inside diameter of the element 2B: 10.04 mm
    The outside diameter of the element 2B: 13.92 mm
    The inside diameter of the element 2C: 14.32 mm
    The outside diameter of the element 2C: 17.26 mm
    The inside diameter of the element 2D: 17.66 mm
    The outside diameter of the element 2D: 20.12 mm
    The inside diameter of the element 2E: 20.56 mm
    The outside diameter of the element 2E: 22.66 mm
    The inside diameter of the element 2F: 23.06 mm
    The outside diameter of the element 2F: 25.00 mm
  • Fig. 2 shows results of a computer simulation calculating conditions of dynamic focusing which occurred while the ultrasonic probe of Figs 1(a) and 1(b) was receiving echo signals. The dynamic focusing is explained in various published documents, for example, the Journal of the Acoustical Society of Japan Vol. 32, No. 6, Jun. 1976, pages 355-361. In the computer simulation related to Fig. 2: the central frequency of the echo signals was set to 3.5 MHz; the pulse length of the ultrasonic wave beam was set equal to three times the wavelength of the central-frequency ultrasonic wave; and the envelope of the pulses of the ultrasonic wave beam was of the half-sine shape or the half-sinusoidal form. In addition, this computer simulation ignored a nonlinear effect on the pulse propagation in an ultrasonic wave transmission medium.
  • It is seen from Fig. 2 that the characteristics of focusing are satisfactory in both of a close examined region and a far examined region. The satisfactorily focusing results from the following facts. In a close examined region, dynamic focusing is effective since only inner piezoelectric elements are used in the dynamic focusing and the inner piezoelectric elements have closer structural focal points. In a far examined region, dynamic focusing is effective since all the piezoelectric elements 2A-2F are used in the dynamic focusing and many piezoelectric elements having far structural focal points are used in the dynamic focusing.
  • The previously-mentioned advantages of this invention which are shown in Fig. 2 denote unexpected results or unobviousness of this invention over the prior art.
  • An ultrasonic probe includes a plurality of piezoelectric elements extending concentrically. The elements have respective surfaces via which ultrasonic wave is transmitted and received. The surfaces of the elements are concave and have predetermined radii of curvature respectively. The radii of curvature increase as the elements are farther from an innermost place and closer to an outermost place.

Claims (2)

  1. An ultrasonic probe comprising:
    a plurality of transducer elements (2A, 2B, 2C, 2D, 2E, 2F) extending concentrically;
    said transducer elements (2A, 2B, 2C, 2D, 2E, 2F) having respective surfaces (4A, 4B, 4C, 4D, 4E, 4F) via which ultrasonic wave is transmitted and received;
    wherein said surfaces (4A, 4B, 4C, 4D, 4E, 4F) of said transducer elements (2A, 2B, 2C, 2D, 2E, 2F) are concave and have predetermined radii of curvature respectively; and
    wherein the radii of curvature increase as said transducer elements (2A, 2B, 2C, 2D, 2E, 2F) are farther from an innermost place and closer to an outermost place;
    said ultrasonic probe being characterized in that
    said plurality of transducer elements (2A, 2B, 2C, 2D, 2E, 2F) are arranged in a transducer element array (1) which has a concave front surface (4);
    said transducer elements (2A, 2B, 2C, 2D, 2E, 2F) are separated by predetermined annular gaps (3); and
    the areas of said respective transducer elements (2A, 2B, 2C, 2D, 2E, 2F) over said front surface (4) are substantially equal to each other.
  2. An ultrasonic probe according to claim 1
    being characterized in that
    said transducer elements are piezoelectric elements (2A, 2B, 2C, 2D, 2E, 2F) arranged in a piezoelectric element array (1).
EP19890122956 1988-12-14 1989-12-12 Ultrasonic probe Expired - Lifetime EP0373603B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP63315422A JPH02159266A (en) 1988-12-14 1988-12-14 Ultrasonic probe
JP315422/88 1988-12-14

Publications (3)

Publication Number Publication Date
EP0373603A2 EP0373603A2 (en) 1990-06-20
EP0373603A3 EP0373603A3 (en) 1991-11-13
EP0373603B1 true EP0373603B1 (en) 1995-03-08

Family

ID=18065191

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890122956 Expired - Lifetime EP0373603B1 (en) 1988-12-14 1989-12-12 Ultrasonic probe

Country Status (3)

Country Link
EP (1) EP0373603B1 (en)
JP (1) JPH02159266A (en)
DE (1) DE68921571T2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105139847A (en) * 2015-08-14 2015-12-09 东南大学 Enhanced acoustic focusing device
US11607194B2 (en) * 2018-03-27 2023-03-21 Koninklijke Philips N.V. Ultrasound imaging system with depth-dependent transmit focus

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0731164B2 (en) * 1989-08-30 1995-04-10 日本碍子株式会社 Ultrasonic flaw detection method for balls
JPH0767452B2 (en) * 1992-01-30 1995-07-26 アロカ株式会社 Ultrasonic diagnostic equipment
GB2315018A (en) * 1996-02-17 1998-01-21 Russell Duncan A wash-basin insert
US6120454A (en) * 1998-02-03 2000-09-19 Boston Scientific Corporation Annular array ultrasound catheter
AU2002228492A1 (en) * 2001-01-05 2002-07-16 Bjorn A.J. Angelsen Annular array
KR20080093281A (en) * 2007-04-16 2008-10-21 주식회사 메디슨 Ultrasound Diagnostic Probe
JP5494959B2 (en) * 2010-05-31 2014-05-21 株式会社日立製作所 Ultrasonic flaw detection sensor and ultrasonic flaw detection method
DE102012204638A1 (en) * 2012-03-22 2013-09-26 Robert Bosch Gmbh Ultrasonic sensor and method for measuring an object distance

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1201197A (en) * 1975-09-15 1986-02-25 Commonwealth Of Australia (The) Variable focus transducer
US4276779A (en) * 1979-03-29 1981-07-07 Raytheon Company Dynamically focussed array
EP0102179B1 (en) * 1982-07-21 1987-09-16 Technicare Corporation Selectable focus ultrasonic transducers for diagnostic imaging
US4760304A (en) * 1986-11-24 1988-07-26 General Electric Company Dark field coaxial ultrasonic transducer

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105139847A (en) * 2015-08-14 2015-12-09 东南大学 Enhanced acoustic focusing device
CN105139847B (en) * 2015-08-14 2018-10-02 东南大学 A kind of Acoustic focusing device of enhancing
US11607194B2 (en) * 2018-03-27 2023-03-21 Koninklijke Philips N.V. Ultrasound imaging system with depth-dependent transmit focus

Also Published As

Publication number Publication date
EP0373603A2 (en) 1990-06-20
DE68921571T2 (en) 1995-08-03
DE68921571D1 (en) 1995-04-13
JPH02159266A (en) 1990-06-19
EP0373603A3 (en) 1991-11-13

Similar Documents

Publication Publication Date Title
EP0372589B1 (en) Ultrasonic probe
US5083568A (en) Ultrasound diagnosing device
US4880012A (en) Ultrasonic probe
US4542653A (en) Apparatus and method for beamforming in an ultrasonic transducer array
US6622562B2 (en) Multi pre-focused annular array for high resolution ultrasound imaging
US4180792A (en) Transmit-receive transducer array and ultrasonic imaging system
US5677491A (en) Sparse two-dimensional transducer array
US5563346A (en) Method and device for imaging an object using a two-dimensional ultrasonic array
US4692654A (en) Ultrasonic transducer of monolithic array type
EP0373603B1 (en) Ultrasonic probe
US20060119223A1 (en) Ultrasound transducer
JPH07270522A (en) Ultrasonic wave transducer for phased array
EP0212737B1 (en) Ultrasonic imaging apparatus
US5901708A (en) Method and apparatus for forming ultrasonic three-dimensional images using cross array
US4784147A (en) Method and apparatus for sidelobe suppression in scanning imaging systems
EP0367117B1 (en) Shock wave generating apparatus forming wide concretion-dis-integrating region by focused shock wave
US4441503A (en) Collimation of ultrasonic linear array transducer
US4445380A (en) Selectable focus sphericone transducer and imaging apparatus
US4487073A (en) Ultrasonic system
US3967234A (en) Depth-of-field arc-transducer and sonar system
US5243567A (en) Sonar beam shaping with an acoustic baffle
US4325258A (en) Conical transducer ultrasonic scanning
JPH06125894A (en) Ultrasonic probe
JPH0419504B2 (en)
JPH0620452B2 (en) Ultrasonic probe

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19891212

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE FR GB

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE FR GB

17Q First examination report despatched

Effective date: 19930824

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB

REF Corresponds to:

Ref document number: 68921571

Country of ref document: DE

Date of ref document: 19950413

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20051207

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20051208

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20051209

Year of fee payment: 17

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20070703

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20061212

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20070831

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20061212

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20070102