Method for manufacturing coil-embedded dust core and coil-embedded dust core

• US 20030214379A1
• Filed: 03/19/2003
• Published: 11/20/2003
• Est. Priority Date: 03/20/2002
• Status: Abandoned Application

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Satoh, Sadaki, Suzuki, Tsuneo, Moro, Hideharu, Tamura, Junetsu
• Application Number:
  US10/392,322
• Publication Number:
  US 20030214379A1
• Time in Patent Office: Days
• US Class Current: 336/200
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/145 characterised by scanning multiple planes
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49071 by winding or coiling
• CPC Class Codes: Y10T 29/49073 by assembling coil and core

Abstract

A method of real time ultrasound imaging of an object in at least three two-dimensional scan planes that are rotated around a common axis, is given, together with designs of ultrasound transducer arrays that allows for such imaging. The method is also introduced into a monitoring situation of cardiac function where, combined with other measurements as for example the LV pressure, physiological parameters like ejection fraction and muscular fiber stress is calculated.

Claims

1. A method for practically real time ultrasound imaging of an object in at least 3 different 2D image planes, the method contains the steps of—

electronically scanning with an ultrasound transducer array a pulsed ultrasound beam with electronically and freely selectable beam directions within at least 3 different sector scan planes that are located with different angular directions around a common axis, the beam direction being switchable both within and between the 2D scan planes from pulse to pulse, and

using the back scattered signal from the pulses in each beam direction to form image data as a function of depth along image sample beam directions,

grouping the image data from each said image sample beam directions together to form 2D images of the object from each scan plane that are obtained with such high frame rate,

so that for practical purposes related to object movements, real time 2D images from said at least 3 different 2D scan planes can be shown on a display screen.

2. A method according to claim 1, where the ultrasound transducer array allows sector scanning of the ultrasound beam within a fixed number of 2D scan planes, where the number of 2D scan planes is at least 3, and a particular 2D scanplane of the said fixed number of 2D scan planes can be selected electronically with negligible switching time for each transmitted pulse.

3. A system for ultrasound imaging of an object in at least 3 different 2D image scan planes according to claim 1, the system comprising—

an ultrasound transducer array that allows sector scanning of the ultrasound beam within at least 3 different 2D scan planes, where the beam direction can be electronically selected from pulse to pulse, freely between the 2D scan planes and within each 2D scan plane,

the transducer array being connected to an imaging instrument that comprises;

means for analyzing the back scattered signal from the beam directions to form image data as a function of depth along the beam directions,

means for grouping the image data from said beam directions to form 2D images of the object from said at least three 2D scan planes,

means for displaying said 2D images of the object on a common display screen in real time,

selecting a scanning pattern of said beams in relation to number of 2D scan planes and movements of the object so that the ultrasound images can be presented with so high frame rate,

that for practical purposes related to the object movements, real time imaging of the moving object in said 2D scan planes is obtained.

4. An ultrasound imaging system according to claim 3, where the 2D scan plane is changed in a circle for each 2D beam sampling, so that a 3D scanning of the object in a spiral cone is obtained, for observation of the object with minimal delays between sampling beams in neighboring 2D scan planes.

5. An ultrasound monitoring system for cardiac function, including an ultrasound 2D imaging system according to claim 1 and also several cardiac physiological measurements.

6. An ultrasound monitoring system for cardiac function according to claim 5, where automatic edge detection is done in the ultrasound images for automatic calculation of the volume of heart cavities, and/or calculation of relative strain in the myocardial fibers.

7. An ultrasound monitoring system for cardiac function according to claim 6, where ventricular dimensions or volume are combined with ventricular pressure measurements to calculate the fiber stress in the cavity walls.

8. An ultrasound monitoring system for cardiac function according to claim 6 or 7, where simultaneous visualization of the multiple scan planes of the heart is done on one part of the display screen, or on a separate display screen, while temporal variation of parameters derived from the ultrasound images and other physiological measurements are shown as a function of time on other parts of the display screen, or on a separate display screen.

9. An ultrasound monitoring instrument for cardiac function according to claim 8, where minimum and maximum values of the temporal traces for each cardiac cycle, are shown in a slow time scale on the same monitor or on a separate monitor.

10. An ultrasound transducer array capable of phased array direction steering and focusing of an ultrasound beam within a set of 2D scan planes that can be electronically selected, where the number of 2D scan planes is at least 3, characterized by that

the array is build up of at least two piezoelectric array layers mounted face to face in a sandwich structure with a front and a back direction,

the back face of the piezoelectric sandwich is mounted on a backing material and the front face of the sandwich is adapted to be connected to the acoustic load material through at least one elastic layer for acoustic impedance interfacing between the piezoelectric layers and the load material,

on each face of the piezoelectric layers is attached a set of parallel finger electrodes where the electrodes are electrically isolated from each other, the directions of the fingers on the front and the back face for each piezoelectric layer forms a non-zero angle to each other,

each set of finger electrodes on said faces are adapted to selectively be connected as the hot element electrodes to a phased array beam former, or connected to the beam former signal ground,

so that selectively connecting the whole set of finger/element electrodes on one side of at least one piezoelectric layer as the hot element electrodes to the beam former, and grounding all other sets of finger electrodes on the other faces of the piezoelectric layers, one obtains a linear phased array transducer where the angular direction of the 2D scan plane around a common axis, is determined by the set of the finger electrodes that are selected as the hot electrodes of the array.

11. An ultrasound transducer array according to claim 10, where the piezoelectric layers are made as a composite of ferroelectric ceramic and polymer, where

the composite structure is the same through all piezoelectric array layers in the sandwich and the ceramic posts of the composite are separated from each other with at least some linear grooves filled with polymer,

said linear grooves conforms with the separations between said finger electrodes on the face of the piezoelectric layers, and hence also the active phased array elements defined by the electrodes connected the hot element wires of said beam former.

12. An ultrasound transducer array composed of two piezoelectric array layers according to claim 11, where

the ceramic posts in said composite structure has a triangular cross section, the triangles being arranged so that the dicing of the ceramic can be done to form straight grooves,

some of said straight grooves filled with polymer defines the separation between the finger electrodes and hence also the selected, active phased array elements,

the finger electrodes of one face of each piezoelectric layer having the same, first direction, while the direction of the finger electrodes of the other faces are different from each other and different from said first direction.

13. An ultrasound transducer array composed of two piezoelectric array layers according to claim 12, where

the ceramic posts in the composite structure has a cross section of an equilateral triangle, the triangles being arranged so that the dicing of the ceramic can be done in straight lines with 60 deg inclination to each other,

the separation of the finger/element electrodes on the piezoelectric layer surface, conforms with straight lines of polymer in the composite, so that the directions of the finger electrodes forms angles of 60 deg with each other.

14. An ultrasound transducer array according to claim 12, where the piezoelectric layers have opposite polarization directions, and

for operation in a lower frequency band in one 2D scan plane normal to said, first direction, the two set of finger electrodes having the same, first direction are connected to each other to form the hot electrodes of a phased array,

while the other set of electrodes are coupled to signal ground so that electric parallel operation of the layers is obtained for operation in a lower frequency band, and

for operation in a higher frequency band with the 2D scan plane also normal to said, first direction, only the electrodes of the front or the back layer with the said, first direction are used as the hot electrodes of the phased array, while all the other sets of finger electrodes are connected to signal ground.

15. An ultrasound transducer array composed of two piezoelectric layers according to claim 10, where the directions of the front and back face finger electrodes for each piezoelectric layer form an angle with each other, and the directions of the back finger electrodes of the front piezoelectric layer and the front finger electrodes of the back piezoelectric layer form an angle with each other, so that all the four sets of finger electrodes on the four faces of the piezoelectric layers forms non-zero angles to each other.

16. An ultrasound transducer array composed of two piezoelectric layers according to claim 15, where the directions of the front and back face finger electrodes for each piezoelectric layer form 90 deg angle with each other, and the directions of the back finger electrodes of the front piezoelectric layer and the front finger electrodes of the back piezoelectric layer form an angle of 45 deg with each other.

17. An ultrasound transducer array according to claim 11 and 16, where the ceramic posts in the composite structure has a cross section of an isosceles triangle with top angles of 90 deg, the triangles being arranged so that the dicing of the ceramic can be done in straight lines with 45 deg inclination to each other.

18. An ultrasound transducer array for phased array imaging with electronic selection of multiple scan plane directions according to claim 10, where

close to the transducer array there is mounted an electronic switching circuit,

the individual finger electrodes of the electrode sets of each piezoelectric layer face are electrically connected to the switching circuit,

the switching circuit being able to connect the electrode set of one freely selectable face of the piezoelectric layers to the hot wires of the ultrasound beam former, while the electrode sets of the other faces of the piezoelectric layers are connected to signal ground.

19. An ultrasound transducer probe composed of an endoscope with an ultrasound array according to claim 10 mounted at the tip of the endoscope to be inserted into an object, for ultrasound imaging of internal structures in the object.

20. An ultrasound transducer probe according to claim 19, where the tip of the endoscope is flexible and where the flex of the tip can be steered by control at the external end of the endoscope.

21. An ultrasound transducer probe according to claim 19, where the array can be rotated in the endoscope tip controlled by means at the external end of the endoscope, or in the imaging instrument.

22. An ultrasound 2D phased array imaging system according to claim 3 capable for operating the multiple set of parallel finger electrodes of a phased array transducer according to claim 10, the ultrasound imaging instrument also providing electronic selection signals to control the electronic selection of which element set is connected to the hot wires of the system, and which element sets are connected to signal ground, for selection of the ultrasound scan planes for 2D imaging, either through manual control from the instrument control panel, or through automatic selection of the scan planes in a sequence, for example changing the scan plane for each beam, or from 2D frame to 2D frame, or changing the scan plane in a slower manner, for example triggered by a signal derived from a physiological signal like the ECG.