Surgery – Truss – Pad
Patent
1989-07-17
1991-07-02
Jaworski, Francis
Surgery
Truss
Pad
29 2535, 310336, 310368, A61B 800
Patent
active
050278223
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
An object of the present invention is a echograph probe with improved connection circuit. It finds application more particularly in the medical field where probes of this type are used for echographic examinations capable of enabling the internal structures of the tissues of an examined human body to be revealed. It can, nonetheless, find application in all the other fields of industry where use is made of echographs, the acoustic signal frequency of which is high. For, the raising of this frequency causes a corresponding reduction in the size of the probes. The result thereof is specific problems of connection due to miniaturization. The present invention proposes a solution thereto.
DISCUSSION OF BACKGROUND piezoelectric crystal.
An echograph comprises, in principle, means to transmit an electrical signal vibrating at an acoustic frequency, a transducer probe receiving this electrical signal and converting it into a mechanical excitation, this probe being applied against a medium to be subjected to an acoustic signal. The back-reflected signal that results from the subjecting of the medium to an acoustic signal is generally received by the same probe during stops in transmission. The probe, which is thus reversible, reconverts the acoustic signal that reaches it into an electrical signal This is applied to receiving elements In the probe, the means that perform the conversion of an electrical signal into an acoustic signal and/or vice versa comprise, in a known way, elements of a piezoelectric crystal The connection device which is an object of the invention concerns the electrical connection of the all the elements of the probe. In one probe, the piezoelectric elements are generally aligned with one another to form a bar. With respect to the acoustic phenomenon, there is distinguished, on this bar, a front face, on the side where the useful acoustic signal is propagated, and a rear face opposite to the front face.
The process of electrical/acoustic conversion takes place most efficiently when the front and rear faces of the elements of the bar are provided with electrodes. During transmission, the electrical signal is applied to these electrodes, it causes the existence of an alternating electrical field in the piezoelectric crystal. This crystal vibrates and emits an acoustic signal. The reverse occurs at reception. The dimensions of the piezoelectrical elements are preferably calculated as a function of the working acoustic frequency of the probe and as a function of the speed of propagation of the waves in the crystal. These two dimensions determine the wavelength .lambda. of the acoustic vibration in the crystal. In the bar, the piezoelectric elements are aligned side by side, parallel to their length, and their height is the distance between the two electrodes. Under these conditions, it is known that the length of the elements should be greater than ten times .lambda., that the height should be substantially equal to .lambda. /2, and that the width, measured orthogonally with respect to these first two dimensions should be smaller than or equal to .lambda. /6. In taking into account a propagation speed of the order of 1500 meters per second, and a working frequency of the order of 7.5 MHz, the elements of the bar should have a width and, hence, a connection pitch smaller than or equal to about 30 micrometers. Furthermore, to prevent stray phenomena of diaphony between adjacent piezoelectrical elements, the method of cutting the piezoelectric elements at their midwidth is known. This has the effect of dividing the connection pitch by two. It becomes of the order of 15 micrometers.
To make the connections, solutions have been developed, in the prior art, inspired by semiconductor technology. In these solutions, a layer of connection wires is applied against each face of the bar. In both these layers, individual connections are assigned to each of the electrodes separated by piezoelectric elements. During fabrication, the two layers extend on either side of the bar lik
REFERENCES:
patent: 4217684 (1980-08-01), Brisken et al.
patent: 4747192 (1988-05-01), Rokurota
patent: 4894895 (1990-01-01), Rokurohta
Patent Abstracts of Japan, vol. 8, No. 206(E-267) (1643), Sep. 20, 1984, & JP, A. 5990498 (Toshiba K.K.) May 24, 1984.
Patent Abstracts of Japan, vol. 5, No. 129(E-70) (801), Aug. 19, 1981, & JP, A. 5666992(Yokogawa Denki Seisakusho K.K.) Jun. 5, 1981.
Dubut Patrick
Elziere Jacques
Gelly Jean-Francois
General Electric CGR SA
Jaworski Francis
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