Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1998-06-08
2001-02-27
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S327000, C310S336000, C310S367000
Reexamination Certificate
active
06194814
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a nosepiece having an integrated faceplate window for phased array transducers, and, more particularly, an integrated faceplate window that provides improved performance, better insertion loss and undisturbed aperture function to improve reliability.
BACKGROUND OF THE INVENTION
As will be used throughout this application, the x, y and z axes will be referred to as the x-elevation axis, the y-azimuthal axis, and the z-range axis.
FIG. 1
is a perspective view of a transducer assembly according to the prior art. The transducer assembly
10
includes a backing block
12
, a layer of transducer material
14
, a first matching layer
16
, a second matching layer
18
, a window
20
and a plastic housing
22
. Also included is a first flex circuit
24
disposed on one surface of the transducer layer
14
and a second flex circuit
26
disposed on an opposite surface of the transducer layer
14
as is well known. The layer of transducer material
14
has a thickness measured in the z-range direction that is constant at each point along the x-elevation axis. The layer of transducer material
14
is flat in the x-elevation direction, i.e., has no curvature. Because the layer of transducer material
14
is flat and has a constant thickness, in order to provide geometrical focusing of an emitted ultrasound beam in the elevation plane, the window
20
disposed over the transducer must be a focusing lens, preferably of a room temperature vulcanized (RTV) silicon material. There are disadvantages associated with such a transducer. The window
20
material is exposed to the environment and thus is exposed to various chemicals including coupling gels when the transducer is in use and disinfectants for cleaning the transducer after use which degrade the integrity of the window. In addition, because the window of the transducer is physically placed against and moved along a surface of the body during imaging, the window is subject to mechanical forces which also degrade the integrity of the window. Also, because the window
20
is formed separately from the plastic housing
22
and is bonded thereto, the bond may be defective or deteriorate over time thus allowing leakage into the housing
22
itself. These chemical and mechanical forces impose stresses on the window of the transducer which introduce problems in the reliability of the transducer and a deterioration in its performance over time.
FIG. 2
is a cross-sectional view taken along the x-elevation axis of another transducer assembly according to the prior art. The transducer assembly
110
, like the transducer assembly
10
shown in
FIG. 1
, includes a backing block
112
, a layer of transducer material
114
of uniform thickness, a first acoustic matching layer
116
, a second acoustic matching layer
118
, a window
120
, a plastic housing
122
and a first and second flex circuit
124
,
126
. Unlike the transducer assembly
10
shown in
FIG. 1
, the layer of transducer material
114
is curved in the x-elevation direction so that both the front and back surfaces
113
,
115
are concave in shape. The curvature of the layer of transducer material
114
provides focusing of an emitted ultrasound beam along the x-elevation axis. Such transducers are known as mechanically focused transducers. Other mechanically focused transducers use a layer of transducer material that has a non-uniform thickness. See U.S. Pat. Nos. 5,438,998 and 5,415,175. Because the layer of transducer material
114
itself provides the focusing, the window material
120
need not be made of focusing material. Like the transducer assembly shown in
FIG. 1
, however, the window
120
is exposed to the environment and separately bonded to the housing
122
and thus suffers from the same disadvantages.
U.S. Pat. No. 5,562,096 (“the '096 patent”) discloses an ultrasonic transducer probe with an axisymmetric lens. The reference numerals in this paragraph refer to the reference numerals in the '096 patent. The transducer probe includes a uniform, flat layer of transducer material 4 with a lens 6 disposed thereover both of which are located in an integrated housing 2. In the region of the housing 2 that is adjacent to the lens 6, the continuous surface 10 of the transducer housing 2 is formed into a window 12. In one embodiment, when a lens 6 is disposed in the housing 2, the thickness of the window 12 is constant. Alternatively, the thickness of the window 12 may vary as a function of distance from axis 8. The window may be formed into an axisymmetric converging lens by increasing the thickness of the window as a function of distance from axis 8. Similarly, the window may be formed into an axisymmetric diverging lens by decreasing the thickness of the window as a function of increasing distance from axis 8. In either of these embodiments the probe can be constructed with or without the lens 6. Preferably, the transducer housing 2 is formed from an acoustically transmissive material such as a thermoplastic material and more particularly, TPX™ from Mitsui Petrochemicals (America).
U.S. Pat. No. 4,387,720 discloses a transducer that includes a flat, uniform thickness array of crystals 2, a focusing lens 15 disposed over the crystals and a non-focusing filler disposed between the transducer layer and the lens. The lens element 14 may be formed of polymethylpentene, polyethylene and polypropylene, all modified with a rubber modifier such as ethylene propylene. The lens element 14 has an outer face 15 that may be flat or slightly curved. An inner lens element 24 is disposed between the outer lens element 14 and a shield 8 and may be formed of a potting compound such as urethane. The outer lens element 14 is a separate piece from nose piece 26. The curvature of the inner surface 15′ of the outer lens element 14 provides the focusing of an emitted ultrasound beam in the elevation plane.
It is thus desirable to provide an ultrasound transducer that has a reliable chemical resistant and high impact resistant shell. It is also desirable to provide an ultrasound transducer that has a seamless design to reduce the possibility of leakage of chemicals into the transducer housing. It is also desirable to provide a transducer that is blood compatible.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided an ultrasound transducer comprising a plurality of transducer elements, each of said elements comprising a first layer of transducer material, the first layer having a first surface and a second surface opposite of the first surface and a thickness measured in a range direction between the first and second surface wherein the thickness of the first layer is uniform. A nosepiece having an integrated faceplate is disposed over the plurality of transducer elements; and a filler material is disposed between the plurality of transducer element and the integrated faceplate.
According to a second aspect of the present invention there is provided an ultrasound transducer comprising:
a plurality of transducer element disposed on a top surface of a backing block, the plurality of transducer elements each having a first surface and a second surface, the second surface opposite of the first surface, wherein the first surface is non-planar in an elevation direction. A nosepiece having an integrated faceplate is disposed over the plurality of transducer elements and a filler material is disposed between the plurality of transducer elements and the integrated faceplate.
According to a third aspect of the invention there is provided an ultrasound transducer comprising:
a plurality of transducer elements, each element comprising a back portion facing away from a region of examination, a front portion opposite of the back portion and two side portions, each of the elements having a thickness measured in a range direction between the front and back portion, the thickness being greater at each of the side portions than between the side portions. A nosepiece having an integrated faceplate is d
DeMartini Richard E.
Hanafy Amin M.
Sperry Russell R.
Spigelmyer Matthew T.
Acuson Corporation
Brinks Hofer Gilson & Lione
Dougherty Thomas M.
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