CA1201197A - Variable focus transducer - Google Patents
Variable focus transducerInfo
- Publication number
- CA1201197A CA1201197A CA000260604A CA260604A CA1201197A CA 1201197 A CA1201197 A CA 1201197A CA 000260604 A CA000260604 A CA 000260604A CA 260604 A CA260604 A CA 260604A CA 1201197 A CA1201197 A CA 1201197A
- Authority
- CA
- Canada
- Prior art keywords
- transducer
- array
- focus
- elements
- varying
- 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
Links
Classifications
-
- 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
- G10K11/34—Sound-focusing or directing, e.g. scanning using electrical steering of transducer arrays, e.g. beam steering
- G10K11/341—Circuits therefor
- G10K11/346—Circuits therefor using phase variation
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/06—Visualisation of the interior, e.g. acoustic microscopy
- G01N29/0609—Display arrangements, e.g. colour displays
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/26—Arrangements for orientation or scanning by relative movement of the head and the sensor
- G01N29/262—Arrangements for orientation or scanning by relative movement of the head and the sensor by electronic orientation or focusing, e.g. with phased arrays
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
- G01S7/52017—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 particularly adapted to short-range imaging
- G01S7/52046—Techniques for image enhancement involving transmitter or receiver
-
- 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
Abstract
ABSTRACT OF THE DISCLOSURE
Apparatus for the ultrasonic examination of an object, e.g. in medical diagnosis, has an arrangement for transmitting pulses of ultrasonic energy into the object and for receiving echoes of the pulses reflected by acoustic impedance discon-tinuities within the object, the arrangement comprising a mechanically prefocused transducer array comprising a central transducer element, the beam axis of the array lying along a line through the center of the central element at right angles thereto, and a plurality of annular transducer elements posi-tioned concentrically of said beam axis; and electronic com-ponents for varying the focus of the transducer array during transmission of the pulses into the object and receipt of the echoes, the transducer array having a spherically curved surface.
Apparatus for the ultrasonic examination of an object, e.g. in medical diagnosis, has an arrangement for transmitting pulses of ultrasonic energy into the object and for receiving echoes of the pulses reflected by acoustic impedance discon-tinuities within the object, the arrangement comprising a mechanically prefocused transducer array comprising a central transducer element, the beam axis of the array lying along a line through the center of the central element at right angles thereto, and a plurality of annular transducer elements posi-tioned concentrically of said beam axis; and electronic com-ponents for varying the focus of the transducer array during transmission of the pulses into the object and receipt of the echoes, the transducer array having a spherically curved surface.
Description
This invention relates to the technique o~
ultrasonic echoscopy of objects and in particular to an extension of known techniques of ultrasonic echoscopy to provide more useful information concerning the examined objects. It is particularly, but not solely, directed to the more effecti.ve acquisition of data in medical diagnosis utilising this technique.
Ultrasonic echoscopy provides information about an examined object which may be displayed in the form of an ultrasonic echogram. Such an echogram consists of a display of acoustic impedance discontinuities or reflecting surfaces in the object. It is obtained by directing a short pulse of ultrasonic energy, typically in the 1-30 MXz frequency range, into the ~m; ned object where any acoustic impedance discontinuities in the object reflect and-return some of -the energy in the form of an echo. This echo is received, converted into an electric signal and di~played as an echogram on a cathode ray oscilloscope, a film, a chart or the like.
The echogram may constitute either a one ~ s~cional or a two dimensional representation and in both cases the in~ormation is contained in the position and magnitude of the echo displayed. In a one ~; n~ional display, the posi~ion along a base line is
ultrasonic echoscopy of objects and in particular to an extension of known techniques of ultrasonic echoscopy to provide more useful information concerning the examined objects. It is particularly, but not solely, directed to the more effecti.ve acquisition of data in medical diagnosis utilising this technique.
Ultrasonic echoscopy provides information about an examined object which may be displayed in the form of an ultrasonic echogram. Such an echogram consists of a display of acoustic impedance discontinuities or reflecting surfaces in the object. It is obtained by directing a short pulse of ultrasonic energy, typically in the 1-30 MXz frequency range, into the ~m; ned object where any acoustic impedance discontinuities in the object reflect and-return some of -the energy in the form of an echo. This echo is received, converted into an electric signal and di~played as an echogram on a cathode ray oscilloscope, a film, a chart or the like.
The echogram may constitute either a one ~ s~cional or a two dimensional representation and in both cases the in~ormation is contained in the position and magnitude of the echo displayed. In a one ~; n~ional display, the posi~ion along a base line is
-2-e~-~, used to indicate the distance to the reflecting surface whilst the magnitude of the echo is displayed, for example, as a deflection of the base line or as an intensity change. In a two dimensional display, the position along a base line is used to indicate the distance to the reflecting surface as in a one dimensional display, and the direction of the base line is used to represent the direction of propagation of the acoustic energy. The two dimensional display is obtained by changing this direction of propagation of the acoustic energy and by instituting a similar but not necessarily identical movement of the base line of the display. The magni~ude of the echo is displ~yed as for a one dimensional display; for example, as a deflection of the base line or as an intensity change.
The technique of ultrasonic echoscopy is used in medical diagnosis to obtain information about the anatomy of patients. The application of this technique is now widely investigated and is described, for example, by D.~. Robinson in Proceedings of the Institution of Radio and Electronics Engineering Australia, Vol. 31, No. 11, pages 385-392, November, 1970: "The Application of Ultrasound in Medical Diagnosis~'. As pointed out in this article, ultrasonic echoscopy may be used to produce displays resembling anatomical cross-sections
The technique of ultrasonic echoscopy is used in medical diagnosis to obtain information about the anatomy of patients. The application of this technique is now widely investigated and is described, for example, by D.~. Robinson in Proceedings of the Institution of Radio and Electronics Engineering Australia, Vol. 31, No. 11, pages 385-392, November, 1970: "The Application of Ultrasound in Medical Diagnosis~'. As pointed out in this article, ultrasonic echoscopy may be used to produce displays resembling anatomical cross-sections
-3-. . . , ; _ _ which have proved clinically useul when the desired information concerns physical dimensions, shapes of organs or structures or the like. Ultrasonic echography has proved of particular value aq a diagnostic aid in the abdomen and pregnant uterus, eye, breast, brain, lung, kidney, liver and heart, these being areas of soft tissue with little bone and air. In general, the technique is considered to complement other techniques to provide a more complete picture of the patients condition, however particularly in pregnancies, ultrasonic echoscspy may be useful in place of x-rays when the latter may not give sufficient information or may be dangerous. In medical use, a pulse of ultrasonic energy is transmitted into a patient in a known direction and echoes are received from reflecting surfaces within the body. The time delay between a transmitted pulse and the received echo depends on the distance from the transmitter to the reflecting surface and the distance information so obtained may be displayed in a suitable way for interpretation and clinical use as a one ~;m~ional range reading or as a two ~; -nqional cross section as previously described.
This known system suffers from a disadvantage due to the extent of the transducer beam in a direction a~ right angles to the beam axis. ~his beam wid~h is
This known system suffers from a disadvantage due to the extent of the transducer beam in a direction a~ right angles to the beam axis. ~his beam wid~h is
-4 .
~2~.3~37 large compared wi~h th~ length of the ultrasonic pulse along the axis and farms the limitation on the resolution of ultrasonic visualisation systems. The beam width can be reduced by geometrically focusing the transducer S by physically curving the face of the transducer, alternatively an acoustic lens can be placed between the transducer and the object to be examined. The degree of focus can be altered by changing the size of the transducer and the focal length of the focusing system with a larger transducer and shorter focal length giving rise to a more sharply focused system. This ~
process of resolution improvement by focusing is limited by diffraction effects to the so called "diffraction limited resolution". With the sharper focusing the distance over which the beam width is small is restricted and it has been customary in pulse echo visualisation to use transducers which are weakly or medium focused to afford the best compromise between beam width resolution and usable range or depth of field. Theoretical discussion of these effects is given in a paper "Design of Narrow Beam Width Transducers", G. Kossoff, J. Acoust.
Soc. Amer.v. 36, n. 6, pages 905-902, June, 1963~
An alternative method of achieving a focusing action is to use a planar transducer surface with a plurality of array elements each connec~ed to a separa~e electronic circuit. In particular, the array elements ~ e-may be composed of a number of concentric rings. The focusing action is achieved by sequentially delaying the siynals from appropriate elements. Thus lf the outer rings are energised first and the inner ones consecutively with an appropriate time delay a concave wave front is produced which converges on a point in the object under ex~m;n~tion. Thus, consecutive transmit pulses can be focused at different ranges to achieve a good focusing action over the entire range of operation. On reception, electronic delay means in the receiver allow waves from a point at a given distance along ~he axis of the array to be aligned and combined to form an effective focus, the ~;ru~ delay being applied to the inner ring or disc and delay being applied sequentially up to a minimum or zero delay being applied to the outer ring.
By varying the delay during the reception period, it is possible to move the position of the ocus so that as signals are picked up from deeper in the object under examination, they always remain in focus. This system is known in the art and described in "Vaxiable ~ocus Transducer", O.H. Schuck, U,S. Patent 3,090,030, May 14, 1963. The ~ nsions of the central disc and surrounding ring elements are fixed by physical requirements. It is ~5 necessary that the distance from any point on ~he axis \
to all parts of the surface of a single element is within one half wave length of the sound wave. This condition is most difficult to satisfy for a point near the transducer and therefore the radius of the central ring is set so that the distance from the nearest point at which echoes are required to the periphery of the disc is exactly one half wave length greater than the distance from the central point of the disc to the field point. Similarly the width of the first ring is fixed so that the distance to the outer edge of the ring exceeds by-one half wave length the distance from the inner edge of ~he ring. This condition leads to a relatively large central disc and successively thinner ring elements. As the transducer size and therefore the ultimate diffraction limited resolution is increased the number of transducer ring elements needed and the amount of electronic delay required to focus at a given distance increases at a rapid rate. This leads to a big increase in cost both of the transducer and the associated electronic circuitry as the number of rings increases.
It is the primary object of the present invention to provide the same performance as a planar electronically focused transducer array ~ut wi~h a reduc~ion in the number of rings and the cost and ~ , :~-z~
complexity of the associated electronic circuitry.
According to the present invention, there is provided apparatus for the ultrasonic examination of an object CQmpriSing means for transmitting pulses of ultrasonic energy into the object and for receiving echoes of the pulses reflected by acoustic impedance discontinuities within the object, the means compris-ing a mechanically prefocused transducer array com-prising a central transducer element, the beam axis of the array lying along a line through the centre of the central element at right angles thereto, and a plurality of annular transducer elements positioned concentrically of the beam axis, and electronic means for varyiny the focus of the transducer array during transmission of the pulses into the object and receipt of the echoes, the transducer array having a spherically curved surface.
The transducer array, having a fixed focus, is arranged to focus the ultrasonic ~eam at some point within the depth range to be used by the ap-paratus. The annular elements can then be made wider, since fewer are required for a given transducer aper-ture, and thus the complexity and cost of the ~z~
transducer array and associated electronic components can be markedly reduced.
An embodiment of the invention is illustrated in the accompanying drawing. In the drawing the trans-ducer 1 is spherical with its focus at point 5 and has applied to it a central circular electrode 2 and a plurality of concentric sets of annular or ring elements illustrated by two rings 3 and 4. One cycle of the electronic operation is initiated by a pulse from the clock 6 which is applied to the time delay elements 7, 8, 9. To achieve the focus point at a distance closer than the geometrically focused point of the transducer the time delay element 7 has zero delay, time delay 8 a small delay and time delay 9 a large delay. The delayed pulses are applied to the transmitter circuits 10, 11 and 12 and thence a transmitter pulse is applied to the electrodes 4, 3 and 2. The emergent wave front 13 is more sharply curved than the transducer face and is focused on the point 14 which is nearer to the transducer than the geometrical focus 5b If the relative time delays 7, 8, 9 are reversed then the emergent wave front 15 would be less sharply curved than the face of the transducer 1, and would focus at a point 16 which is further distant than the geometric focus 5.
_ g _ ~3 ~O~ 7 Thus a transmitted wave can be focused at any required distance from the transducer and the distance can be changed for consecutive pulses. On reception a sim1lar action occurs in reverse, echoes from the near point 14 give rise to a sharply curved wave front 13 and echoes from the far point 16 give rise to a less curved wave front 15. By using time delay elements 17, 18, 19 which may be varied electronically during the time the echoes are returning it is possible to effectively focus at each distance as echoes from tha~ distance are being received. This means that at the com~ncement of the receive period when echoes axe arriving from near echo point 14 time delay element 17 has a large time delay, time delay element 18 has a smaller time delay an-d~
time delay element 19 has no time delay and echoes from wavefront 13 all arrive simultaneously àt the adder 20.
As echoes from more distant points are received the relative time delays must be re~ersed to focus for flatter wavefronts such as wave~ront 15 originating at far point 16. Electronic circuitry to achieve the functions o~ the clock 6, pulsed time delay elements 7, 8, 9, transmitters 10, 11, 12, analogue time delay elements 17, 18, 19, and adder 20 are well known in the art and detailed description thereo is not considered necessary in the present specification.
~?,~ 7 It will be appreciated that the schematic representation included herein is included by way of example only, and not by way of limitation of the present invention. Many variations and modifications may be made to the embodiment described herein without departing from the concept of the present invention, and all such variations and modifications are included within the scope of the invention.
~2~.3~37 large compared wi~h th~ length of the ultrasonic pulse along the axis and farms the limitation on the resolution of ultrasonic visualisation systems. The beam width can be reduced by geometrically focusing the transducer S by physically curving the face of the transducer, alternatively an acoustic lens can be placed between the transducer and the object to be examined. The degree of focus can be altered by changing the size of the transducer and the focal length of the focusing system with a larger transducer and shorter focal length giving rise to a more sharply focused system. This ~
process of resolution improvement by focusing is limited by diffraction effects to the so called "diffraction limited resolution". With the sharper focusing the distance over which the beam width is small is restricted and it has been customary in pulse echo visualisation to use transducers which are weakly or medium focused to afford the best compromise between beam width resolution and usable range or depth of field. Theoretical discussion of these effects is given in a paper "Design of Narrow Beam Width Transducers", G. Kossoff, J. Acoust.
Soc. Amer.v. 36, n. 6, pages 905-902, June, 1963~
An alternative method of achieving a focusing action is to use a planar transducer surface with a plurality of array elements each connec~ed to a separa~e electronic circuit. In particular, the array elements ~ e-may be composed of a number of concentric rings. The focusing action is achieved by sequentially delaying the siynals from appropriate elements. Thus lf the outer rings are energised first and the inner ones consecutively with an appropriate time delay a concave wave front is produced which converges on a point in the object under ex~m;n~tion. Thus, consecutive transmit pulses can be focused at different ranges to achieve a good focusing action over the entire range of operation. On reception, electronic delay means in the receiver allow waves from a point at a given distance along ~he axis of the array to be aligned and combined to form an effective focus, the ~;ru~ delay being applied to the inner ring or disc and delay being applied sequentially up to a minimum or zero delay being applied to the outer ring.
By varying the delay during the reception period, it is possible to move the position of the ocus so that as signals are picked up from deeper in the object under examination, they always remain in focus. This system is known in the art and described in "Vaxiable ~ocus Transducer", O.H. Schuck, U,S. Patent 3,090,030, May 14, 1963. The ~ nsions of the central disc and surrounding ring elements are fixed by physical requirements. It is ~5 necessary that the distance from any point on ~he axis \
to all parts of the surface of a single element is within one half wave length of the sound wave. This condition is most difficult to satisfy for a point near the transducer and therefore the radius of the central ring is set so that the distance from the nearest point at which echoes are required to the periphery of the disc is exactly one half wave length greater than the distance from the central point of the disc to the field point. Similarly the width of the first ring is fixed so that the distance to the outer edge of the ring exceeds by-one half wave length the distance from the inner edge of ~he ring. This condition leads to a relatively large central disc and successively thinner ring elements. As the transducer size and therefore the ultimate diffraction limited resolution is increased the number of transducer ring elements needed and the amount of electronic delay required to focus at a given distance increases at a rapid rate. This leads to a big increase in cost both of the transducer and the associated electronic circuitry as the number of rings increases.
It is the primary object of the present invention to provide the same performance as a planar electronically focused transducer array ~ut wi~h a reduc~ion in the number of rings and the cost and ~ , :~-z~
complexity of the associated electronic circuitry.
According to the present invention, there is provided apparatus for the ultrasonic examination of an object CQmpriSing means for transmitting pulses of ultrasonic energy into the object and for receiving echoes of the pulses reflected by acoustic impedance discontinuities within the object, the means compris-ing a mechanically prefocused transducer array com-prising a central transducer element, the beam axis of the array lying along a line through the centre of the central element at right angles thereto, and a plurality of annular transducer elements positioned concentrically of the beam axis, and electronic means for varyiny the focus of the transducer array during transmission of the pulses into the object and receipt of the echoes, the transducer array having a spherically curved surface.
The transducer array, having a fixed focus, is arranged to focus the ultrasonic ~eam at some point within the depth range to be used by the ap-paratus. The annular elements can then be made wider, since fewer are required for a given transducer aper-ture, and thus the complexity and cost of the ~z~
transducer array and associated electronic components can be markedly reduced.
An embodiment of the invention is illustrated in the accompanying drawing. In the drawing the trans-ducer 1 is spherical with its focus at point 5 and has applied to it a central circular electrode 2 and a plurality of concentric sets of annular or ring elements illustrated by two rings 3 and 4. One cycle of the electronic operation is initiated by a pulse from the clock 6 which is applied to the time delay elements 7, 8, 9. To achieve the focus point at a distance closer than the geometrically focused point of the transducer the time delay element 7 has zero delay, time delay 8 a small delay and time delay 9 a large delay. The delayed pulses are applied to the transmitter circuits 10, 11 and 12 and thence a transmitter pulse is applied to the electrodes 4, 3 and 2. The emergent wave front 13 is more sharply curved than the transducer face and is focused on the point 14 which is nearer to the transducer than the geometrical focus 5b If the relative time delays 7, 8, 9 are reversed then the emergent wave front 15 would be less sharply curved than the face of the transducer 1, and would focus at a point 16 which is further distant than the geometric focus 5.
_ g _ ~3 ~O~ 7 Thus a transmitted wave can be focused at any required distance from the transducer and the distance can be changed for consecutive pulses. On reception a sim1lar action occurs in reverse, echoes from the near point 14 give rise to a sharply curved wave front 13 and echoes from the far point 16 give rise to a less curved wave front 15. By using time delay elements 17, 18, 19 which may be varied electronically during the time the echoes are returning it is possible to effectively focus at each distance as echoes from tha~ distance are being received. This means that at the com~ncement of the receive period when echoes axe arriving from near echo point 14 time delay element 17 has a large time delay, time delay element 18 has a smaller time delay an-d~
time delay element 19 has no time delay and echoes from wavefront 13 all arrive simultaneously àt the adder 20.
As echoes from more distant points are received the relative time delays must be re~ersed to focus for flatter wavefronts such as wave~ront 15 originating at far point 16. Electronic circuitry to achieve the functions o~ the clock 6, pulsed time delay elements 7, 8, 9, transmitters 10, 11, 12, analogue time delay elements 17, 18, 19, and adder 20 are well known in the art and detailed description thereo is not considered necessary in the present specification.
~?,~ 7 It will be appreciated that the schematic representation included herein is included by way of example only, and not by way of limitation of the present invention. Many variations and modifications may be made to the embodiment described herein without departing from the concept of the present invention, and all such variations and modifications are included within the scope of the invention.
Claims (16)
1. Variable focus transducer means for trans-mitting and receiving ultrasonic waves comprising:
a transducer array including a central transducer element and at least one annular transducer element surrounding said central element;
said transducer elements arranged to provide a concavely curved surface for acoustically focusing said ultrasonic waves; and electrical means for electrically varying the focus of said transducer array.
a transducer array including a central transducer element and at least one annular transducer element surrounding said central element;
said transducer elements arranged to provide a concavely curved surface for acoustically focusing said ultrasonic waves; and electrical means for electrically varying the focus of said transducer array.
2. Variable focus transducer means for trans-mitting and receiving ultrasonic waves comprising:
a transducer array including a central transducer element and at least one annular transducer element surrounding said central element;
acoustic wave focusing means associated with the transducer for acoustically focusing said ultrasonic waves;
and electrical means for electrically varying the focus of said transducer array.
a transducer array including a central transducer element and at least one annular transducer element surrounding said central element;
acoustic wave focusing means associated with the transducer for acoustically focusing said ultrasonic waves;
and electrical means for electrically varying the focus of said transducer array.
3. Variable focus transducer means for trans-mitting and receiving ultrasonic waves comprising:
a transducer array including a central transducer element and at least one annular transducer element surrounding said central element;
acoustic wave focusing means associated with the transducer for providing the same with an acoustical focal point; and electrical means connected to said electrodes for varying the focal point established by said acoustic wave focusing means.
a transducer array including a central transducer element and at least one annular transducer element surrounding said central element;
acoustic wave focusing means associated with the transducer for providing the same with an acoustical focal point; and electrical means connected to said electrodes for varying the focal point established by said acoustic wave focusing means.
4. Variable focus transducer means as claimed in claim 1 wherein:
said electrical means comprise electrically variable time delay means for electrically varying the acoustical focusing.
said electrical means comprise electrically variable time delay means for electrically varying the acoustical focusing.
5. Variable focus transducer means as claimed in claim 1, wherein:
said electrical means comprise a plurality of sequentially operated transmitters connected to individual transducer elements for electrically varying the acoustical focusing.
said electrical means comprise a plurality of sequentially operated transmitters connected to individual transducer elements for electrically varying the acoustical focusing.
6. Variable focus transducer means as claimed in claim 2, wherein said acoustic wave focusing means is of the fixed focus type.
7. The variable focus transducer means as claimed in claim 2, wherein said acoustic wave focusing means includes means forming said transducer with a concave active face.
8. Variable focus transducer means as claimed in claim 2, wherein said electrical means comprise electrically variable time delay means for electrically varying the focal point.
9. Variable focus transducer means as claimed in claim 2, wherein said electrical means comprise a plurality of sequentially operated transmitters connected to individual transducer elements for electrically varying the acoustical focal point.
10. Variable focus transducer means as claimed in claim 3,wherein said acoustic wave focusing means is of the fixed focus type.
11. Variable focus transducer means as claimed in claim 3,wherein said acoustic wave focusing means includes means forming said transducer with a concave active face.
12. Apparatus for the ultrasonic examination of an object comprising means for transmitting pulses of ultrasonic energy into the object and for receiving echoes of said pulses reflected by acoustic impedance discontinuities within the object, said means comprising a mechanically prefocused transducer array comprising a central transducer element, the beam axis of the array lying along a line through the centre of said central element at right angles thereto, and a plurality of annular transducer elements positioned concentrically of said beam axis, and electronic means for varying the focus of said transducer array during transmission of said pulses into said object and receipt of said echoes, said transducer array having a spherically curved surface.
13. Apparatus according to claim 12, wherein said electronic means for varying the focus of said transducer array during transmission of said pulses comprises means for energizing the elements of said array at progressively different times.
14. Apparatus according to claim 13, wherein said means for energizing the elements of said array includes pulse generating means and a time delay element associated with each of said transducer elements to delay application of the transmission pulse to said transducer element.
15. Apparatus according to claim 12 wherein said electronic means for varying the focus of said transducer array during receipt of said echoes comprises means to progressively delay signals produced by the elements of said array on receipt of said echoes.
16. Apparatus according to claim 15, wherein said means to progressively delay signals produced by the elements of said array includes a time delay element associated with each of said transducer elements to delay signals produced by said transducer element on receipt of said echoes, and means for adding progressively delayed signals produced by said time delay elements.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPC315175 | 1975-09-15 | ||
| AUPC3151 | 1975-09-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1201197A true CA1201197A (en) | 1986-02-25 |
Family
ID=3766362
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000260604A Expired CA1201197A (en) | 1975-09-15 | 1976-09-07 | Variable focus transducer |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5256781A (en) |
| AT (1) | AT378115B (en) |
| CA (1) | CA1201197A (en) |
| DE (1) | DE2641265A1 (en) |
| FR (1) | FR2324004A1 (en) |
| GB (1) | GB1514050A (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1554349A (en) * | 1976-11-01 | 1979-10-17 | Stanford Res Inst Int | Variable focus ultrasonic transducer means |
| JPS58333B2 (en) * | 1977-08-22 | 1983-01-06 | アロカ株式会社 | Ultrasound diagnostic equipment |
| JPS595298B2 (en) * | 1977-09-02 | 1984-02-03 | 株式会社日立メディコ | Ultrasonic imaging device |
| JPS55500006A (en) * | 1977-12-12 | 1980-01-10 | ||
| US4155259A (en) * | 1978-05-24 | 1979-05-22 | General Electric Company | Ultrasonic imaging system |
| US4155258A (en) * | 1978-05-24 | 1979-05-22 | General Electric Company | Ultrasonic imaging system |
| US4241610A (en) * | 1979-02-05 | 1980-12-30 | Varian Associates, Inc. | Ultrasonic imaging system utilizing dynamic and pseudo-dynamic focusing |
| JPS5672857A (en) * | 1979-11-16 | 1981-06-17 | Matsushita Electric Ind Co Ltd | Method of scanning ultrasonic diagnosing device |
| JPS58133240A (en) * | 1982-02-01 | 1983-08-08 | 株式会社東芝 | Ultrasonic diagnostic apparatus |
| US4442713A (en) * | 1982-03-09 | 1984-04-17 | Sri International | Frequency varied ultrasonic imaging array |
| FR2592720B1 (en) * | 1986-01-03 | 1988-08-05 | Peugeot & Renault | APPARATUS FOR EXAMINING MEDIA BY ULTRASONIC ECHOGRAPHY |
| JPH01153145A (en) * | 1987-12-11 | 1989-06-15 | Toshiba Corp | Annular array ultrasonic probe |
| JPH02159266A (en) * | 1988-12-14 | 1990-06-19 | Matsushita Electric Ind Co Ltd | Ultrasonic probe |
| FR2773459B1 (en) * | 1998-01-12 | 2000-04-14 | Centre Nat Rech Scient | PROCESS FOR EXPLORING AND VISUALIZING TISSUES OF HUMAN OR ANIMAL ORIGIN FROM A HIGH FREQUENCY ULTRASONIC SENSOR |
| CN104359980B (en) * | 2014-11-24 | 2017-01-04 | 清华大学 | A kind of zigzag columnar ultrasound phase array transducer |
| JP7145799B2 (en) | 2019-03-19 | 2022-10-03 | 株式会社東芝 | ultrasonic inspection equipment |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR876822A (en) * | 1940-11-18 | 1942-11-18 | Atlas Werke Ag | Device for the production of converging sound fields |
| GB941573A (en) * | 1959-11-06 | 1963-11-13 | Kelvin & Hughes Ltd | Improvements in flaw detection and like systems using pulsed sonic or ultrasonic waves |
| DE2202989A1 (en) * | 1972-01-21 | 1973-07-26 | Siemens Ag | FOCUSED ULTRASONIC CONVERTER |
| AU483477B2 (en) * | 1972-06-08 | 1977-05-18 | Commonwealth Of Australia, The | Wide aperture ultrasonic array |
| DE2345155B2 (en) * | 1973-09-07 | 1975-09-25 | Krautkraemer Gmbh, 5000 Koeln | Group-wise keyed ultrasonic probe system for non-destructive testing of materials, consisting of cell-shaped and / or perpendicular thereto, strip-shaped arranged individual transducer elements |
-
1976
- 1976-09-07 CA CA000260604A patent/CA1201197A/en not_active Expired
- 1976-09-13 GB GB37754/76A patent/GB1514050A/en not_active Expired
- 1976-09-14 AT AT0679076A patent/AT378115B/en not_active IP Right Cessation
- 1976-09-14 DE DE19762641265 patent/DE2641265A1/en not_active Withdrawn
- 1976-09-15 FR FR7627680A patent/FR2324004A1/en active Granted
- 1976-09-16 JP JP51110017A patent/JPS5256781A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE2641265A1 (en) | 1977-03-17 |
| FR2324004A1 (en) | 1977-04-08 |
| GB1514050A (en) | 1978-06-14 |
| FR2324004B1 (en) | 1982-01-08 |
| JPS5256781A (en) | 1977-05-10 |
| JPS6148947B2 (en) | 1986-10-27 |
| ATA679076A (en) | 1984-11-15 |
| AT378115B (en) | 1985-06-25 |
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