Compact electrical connections for ultrasonic transducers

An element connection assembly for connecting elements of an ultrasonic transducer stack mounted on a frame to wires of a cable and having a plurality of transmitting and receiving elements and including a element lead assembly and a connection assembly. The element lead assembly has a plurality of leads connected to the element connections, is located along a first side of the frame and includes a first and second lead zone areas spaced apart transverse to the longitudinal axis of the frame and separated by a folding line. Groups of leads are routed through corresponding lead zone areas and turn through a right angle to pass across the first lead zone area transverse to the longitudinal axis of the frame and there is a connection pad for connecting each lead to a wire of the cable. The element lead assembly is folded along the folding line so that the second lead zone area is superimposed over the first lead zone area so that the width of the element lead assembly along the frame is equal to or less than the width of the connection side of the frame. The element lead assembly includes a third lead zone wherein the leads are connected to the corresponding connection pads on a second side of the frame and a connector for connecting the wires of the cable to the leads and may include a second element lead assembly and connection assembly located on an opposite side of the frame.

FIELD OF THE INVENTION 
The present invention relates to a design and the method of constructing 
ultrasonic transducers and, in particular, a design and method for 
connecting to the elements of an ultrasonic transducer. 
BACKGROUND OF THE INVENTION 
Ultrasonic transducers are used in many medical applications and, in 
particular, for the non-invasive acquisition of images of organs and 
conditions within a patient, typical examples being the ultrasound imaging 
of fetuses and the heart. The ultrasonic transducers used in such 
applications are generally hand held, and must meet stringent dimensional 
constraints in order to acquire the desired images. For example, it is 
frequently necessary that the transducer be able to obtain high resolution 
images of significant portions of a patient's chest cavity through the gap 
between two ribs when used for cardiac diagnostic purposes, thereby 
severely limiting the physical dimensions of the transducer. As a 
consequence, and because of the relatively small aperture between human 
ribs and similar constraints upon transducer positioning when attempting 
to gain images of other parts of the human body, there has been 
significant development of linear or phased array transducers comprising 
multiple transmitting and receiving elements, with the associated 
electronics and switching circuits, to provide relatively narrowly focused 
and "steerable" transmitting and receiving "beams". 
Many such transducers are comprised of a one element wide by multiple 
element long linear array of transmitting and receiving elements arranged 
in line along a flat plane or, preferably, along a concave or convex arc, 
thereby providing a greater scanning arc. The transmitting and receiving 
beams of such transducers are formed and steered by selecting individual 
transducers elements or groups of transducer elements to transmit or 
receive ultrasonic energy, wherein each such individual transducer element 
or group of transducers elements forms an "aperture" of the transducer 
array. Such an array is thereby formed of a single row of apertures 
extending along the face of the array and such transducers are 
consequently referred to as "single aperture" transducers. 
There also transducers that are capable of scanning or focusing in 
elevation as well as azimuth, that is, along the axis at right angles to 
the azimuth plane along which the elements are arrayed as well as along 
the azimuth plane. As is well understood, the formation, steering and 
focusing of the transmitting and receiving beams of a transducer are 
controlled by selection and use of the various separate physical divisions 
or areas of transducer material comprising the transducer array, which, as 
described above, are referred to as "apertures". In contrast to "single 
aperture" transducers, however, in which each aperture is formed by an 
element or group of elements extending across the face of the array as a 
single unitary area or division or the array, each corresponding element 
in a transducer capable of scanning in elevation is divided into multiple 
sub-elements, or segments. For this reason, and because each element 
position along such an array can form multiple apertures, that is, using 
different combinations of the sub-elements or segments of each of the 
transducer elements, such transducers are consequently referred to as 
"multiple aperture" transducers. The shape, focus and direction of the 
transmitting and receiving beams of a multiple aperture transducer are 
again controlled by selection of the apertures of the array. In a multiple 
aperture array, however, each aperture is formed by one or more of the 
sub-elements, or segments, of the transducer elements, so that the 
apertures of a multiple aperture array can be used to steer and focus the 
transducer scan beam along the elevation axis as well as along the azimuth 
axis and can define multiple azimuthal scan planes, each being at a 
different angle of elevation. 
Single and multiple aperture transducers are generally constructed from a 
single piece of transducer material having a width equal to the length of 
one element and a length equal to the widths of the total number of 
elements, plus spaces between the elements. One or more element 
interconnection circuits providing conductive connections and paths 
interconnecting the individual elements or segments and forming the 
apertures of the transducer are bonded to one side of the piece of 
transducer material and a layer or layers of matching material may be 
bonded to the radiating and receiving side of the transducer material. The 
assembly comprised of the transducer material, element interconnection 
circuits and matching layers, if any, is referred to as a "stack" and a 
temporary or permanent layer of backing material of some form, such as a 
flexible material, may be bonded to the back of the stack, for example, to 
aid in handling the stack during manufacture or to comprise a part of the 
structure of the finished transducer assembly. In addition, one or more 
layers of impedance matching material is often superimposed upon the 
transducer elements to match the acoustic impedance of the transducer to 
the body or material being scanned, and a lens comprised of a suitable 
material may be additionally superimposed upon the impedance matching 
material to shape or focus the beams generated by the transducer elements. 
In some implementations, the impedance matching layers may have suitable 
acoustic characteristics and may be shaped to operate as an acoustic lens. 
A transducer is used in conjunction with a set of transducer electronics 
that typically include transmitting electronics for driving the aperture 
elements and segments to generate the ultrasonic signals transmitted by 
the transducer, receiving electronics for receiving the signals 
representing the returned ultrasonic signals, and switching elements for 
selectively connecting the transmitting and receiving electronics to the 
elements and segments of the apertures to select the aperture or apertures 
for each transmitted or received signal. It is therefore necessary to 
provide electrical connections between the apertures, that is, the element 
interconnection circuits interconnecting the elements and segments of the 
transducer array to form the apertures, and the transducer electronics and 
these connections are typically provided through flexible printed circuits 
and wires running along the body of the transducer. 
Providing the electrical connections between the transducer electronics and 
the elements, sub-elements and segments of the arrays remains a primary 
problem in constructing transducers, however, particularly as the number 
of apertures increases. That is, the physical dimensions of an array, 
especially for medical use, is generally constrained, for example, by the 
need to scan the cardiac structures through the space between patient's 
ribs to avoid interference by the ribs. A typical transducer, however, 
will contain 96 to 128 or more elements or segments which may be used 
individually or in combinations as apertures, each of which must be 
individually connected to the transducer electronics. 
In a typical transducer, the element interconnection circuits may be 
comprised, for example, of flexible printed circuits while the connections 
to the elements and segments are typically brought out for connection to 
the transducer electronics through a flexible printed circuit. The 
flexible printed circuit has a lead for each aperture of the transducer 
and each flexible printed circuit lead is, in turn, connected to a wire of 
a cable connected to the transducer electronics. In other designs, the 
wires of the cable connected to the transducer electronics may be 
connected directly to the element interconnection circuits. 
The flexible printed circuit leads and cable wires connecting the apertures 
connected to the transducer electronics are typically laid out in a 
transverse orientation relative to the element array, that is, in a 
straight line from the transducer, so that each flexible printed circuit 
lead and corresponding cable wire lie in a straight line, thereby 
requiring a space per wire of at least the diameter of the wire. The 
flexible printed circuit, the connections between the flexible printed 
circuit and the cable, and the transducer end of the cable are typically 
contained within the transducer case, that is, in the "handle" section of 
the transducer behind the transducer head, and, in a typical 96 to 128 
element transducer, thereby require substantial width in the transducer 
case. This, in turn, results in a relatively bulky and hard to handle 
transducer. 
While it is possible to reduce the size of the transducer "handle", this 
has typically been accomplished only at the cost of reducing the width of 
the flexible printed circuit leads and the thickness of the cable wires. 
This approach, however, results in a mechanically more fragile assembly 
that is harder to manufacture and more prone to breakage in normal use and 
that may degrade the quality of the signals between the transducer and the 
transducer electronics. 
In addition, the wires of the cable are typically soldered directly to the 
flexible printed circuit or, in alternate designs, are run up to the stack 
and soldered or welded directly to the element interconnection circuits. 
This requires that the cable wires not only be soldered to the flexible 
printed circuit during manufacture, but also unsoldered from and 
resoldered to the flexible printed circuit for repairs to the cable or 
transducer. Because of the relatively high temperatures involved in 
soldering and desoldering operations, and in welding operations, there is 
a significant risk to damage to the flexible printed circuit as well as to 
the relative fine wires of the cable each time the connections are 
soldered or unsoldered. As a result, the flexible printed circuit and 
cable wires can be detached and reconnected only a few times before the 
cable assembly must be rebuilt or replaced, or the flexible printed 
circuit is degraded to the point it must be replaced. Also, the transducer 
stack itself may be damaged in those designs wherein the wires are 
soldered directly to element interconnection circuits of the stack, so 
that the transducer stack may have to be replaced. 
Finally, it will be noted that the above problems become more difficult 
with each new generation of transducer designs as there is a need and 
trend to increase the number of elements or sub-elements to achieve ever 
finer scan resolution to achieve increasingly detailed images of the 
anatomic structures, and a correspondingly greater number of connections 
to be provided. 
The present invention provides a solution to these and other problems of 
the prior art. 
SUMMARY OF THE INVENTION 
The present invention is directed to an element connection assembly for 
connecting elements of the transducer stack of an ultrasonic transducer to 
wires of a cable connecting to transducer electronics wherein the 
transducer stack is mounted on a generally elongated frame for 
manipulation of the transducer stack and has a plurality of elements for 
transmitting and receiving ultrasonic signals. 
According to the present invention, the element connection assembly 
includes a element lead assembly and a connection assembly wherein the 
element lead assembly has a plurality of leads for and corresponding to 
certain of the element connections, a first end of each lead being 
connected to an element, and wherein the element lead assembly is located 
along a first side of the frame between the transducer stack and an end of 
the frame and includes a first lead zone area and a second lead area zone, 
the lead zone areas being spaced apart transverse to the longitudinal axis 
of the frame and separated from one another by a folding line. The leads 
are organized into groups corresponding to the lead zone areas wherein 
with each group of leads being routed through a corresponding lead zone 
area and turning through a right angle to pass across the first lead zone 
area in a direction transverse to the longitudinal axis of the frame. The 
connection assembly has a connection pad for and corresponding to each 
lead for connection to a corresponding wire of the cable connected to the 
transducer electronics, wherein each lead is connected to a corresponding 
connection pad. The element lead assembly is folded along the folding line 
so that the second lead zone area is superimposed over the first lead zone 
area so that the width of the element lead assembly along the frame is 
equal to or less than the width of the connection side of the frame. 
In a presently preferred embodiment, the element lead assembly further 
includes a third lead zone area extending transversely from the first lead 
zone area wherein the leads extend into the third lead zone area wherein 
the leads are connected to the corresponding connection pads and the third 
lead zone area is bent through a right angle relative to the first side of 
the frame so that the connection assembly and the connections of the leads 
to the connection pads on the connection assembly are located on a second 
side of the frame. 
In further embodiments, the connection assembly further includes at least 
one connector having pins corresponding to and connected to corresponding 
ones of the connection pads and the flexible circuit is terminated into 
the connector for connecting the wires of the cable to the leads through 
the connection assembly, the wires being terminated on the back side of 
the board. 
In the presently preferred embodiment, the element lead assembly further 
includes a second element lead assembly and connection assembly located 
respectively on an opposite side of the frame from the first element lead 
assembly and connection assembly and connecting others of the element 
connections to corresponding wires of the cable connected to the 
transducer electronics. In this embodiment, the wires of the cable 
connected to the transducer electronics are organized into groups 
corresponding to the element connections of the first and second element 
lead assemblies and connection assemblies for connection respectively to 
the leads of the first and second element lead assemblies. 
Lastly, in the presently preferred embodiment, the element lead assembly is 
comprised of a flexible circuit and the connection assembly is comprised 
of a rigid circuit board. 
Other features, objects and advantages of the present invention will be 
understood by those of ordinary skill in the art after reading the 
following descriptions of a present implementation of the present 
invention, and after examining the drawings, wherein:

DESCRIPTION OF A PRESENTLY PREFERRED EMBODIMENT 
Referring to FIG. 1, therein is shown an exploded partial isometric view of 
a Transducer 10 constructed according to the present invention. As shown 
therein, Transducer 10 includes an Acoustic Stack 12 that, as described 
herein above, is comprised of a transducer array of radiating and 
receiving elements or segments formed, for example, of piezoelectric 
material. As also described, Acoustic Stack 12 may also include a layer or 
layers of matching material and a temporary or permanent layer of backing 
material of some form, such as a flexible material, bonded to the back of 
Acoustic Stack 12. 
Acoustic Stack 12 is mounted on a Backing 14, which in turn is mounted on a 
Frame 16 which, as described further below, provides a core for a handle 
by which the user can manipulate the transducer and a support for a wiring 
assembly according to the present invention for connecting the element 
interconnection circuits of Acoustic Stack 12 to a Cable 18 connected to 
the Transducer Electronics 20. As has been described herein above, 
Transducer Electronics 20 typically include transmitting electronics for 
driving the aperture elements and segments to generate the ultrasonic 
signals transmitted by the transducer, receiving electronics for receiving 
the signals representing the returned ultrasonic signals, and switching 
elements for selectively connecting the transmitting and receiving 
electronics to the elements and segments of the apertures to select the 
aperture or apertures for each transmitted or received signal. 
According to the present invention, the element interconnection circuits of 
Acoustic Stack 12 are connected to the wires of Cable 18 to Transducer 
Electronics 20 through a Element Connection Assembly 22 that includes a 
Element Lead Assembly 24 comprised, for example, of a flexible printed 
circuit, and a Connection Assembly 26 comprised, for example, of a rigid 
printed circuit board. As shown, Element Lead Assembly 24 extends from 
Acoustic Stack 12, and in particular from a point directly adjoining the 
element interconnection circuits of Acoustic Stack 12, and along Frame 16 
to meet with Connection Assembly 26 which in turn is generally located 
adjacent the "back" end of Frame 16, that is, the end of Frame 16 away 
from Acoustic Stack 12 and convenient for connection to Cable 18. It will 
be noted, as indicated generally in FIG. 1 and as described in detail 
below, that Element Lead Assembly 24 is represented as being folded over 
on itself along an axis substantially parallel to the longitudinal axis of 
Frame 16, thereby significantly reducing the width of Element Lead 
Assembly 24 along Frame 16. 
In this regard, it must be noted that for purposes of clarity FIG. 1 
illustrates a single "side" of Transducer 10 and shows Element Connection 
Assembly 22 as comprised of a single Element Lead Assembly 24 and a single 
Connection Assembly 26 and that the exemplary embodiment shown herein will 
be described with reference to the single Element Lead Assembly 24 and 
single Connection Assembly 26 illustrated in FIG. 1. In the presently 
preferred embodiment, however, and generally in embodiments wherein the 
transducer array of Acoustic Stack 12 includes relatively large numbers of 
elements or segments, for example, 96 to 128 or more elements or segments, 
Element Connection Assembly 22 will be comprised of two Element Lead 
Assemblies 24 and two Connection Assemblies 26, wherein there will be a 
Element Lead Assembly 24 and a Connection Assembly 26 on each "side" of 
Acoustic Stack 12 and Frame 16. This implementation is illustrated in FIG. 
5, which illustrates the mounting of two Element Connection Assemblies 22, 
each comprising an Element Lead Assembly 24 and a Connection Assembly 26, 
to opposing sides of Frame 16. It will be recognized by those of ordinary 
skill in the relevant arts, however, that in certain embodiments of the 
present invention Element Connection Assembly 22 may be comprised of a 
single Element Lead Assembly 24 and a single Connection Assembly 26. 
As generally shown in FIG. 1 and as will be described in further detail 
below, Element Lead Assembly 24 is located on a Connection Side 28 of 
Frame 16, wherein Connection Side 28 of Frame 16 is located along and 
abuts the longitudinal side of the element array of Acoustic Stack 12, 
that is, the edge of the element array wherein Element Connections 30 to 
the element interconnection circuits are brought out of the element array 
and are accessible for connection to Transducer Electronics 20. Element 
Lead Assembly 24 includes a plurality of Leads 32, one for each connection 
to be made to a corresponding lead or conductive path of the element 
interconnection circuits of Acoustic Stack 12, which terminate at the end 
adjoining Acoustic Stack 12 in a corresponding plurality of Stack 
Connection Tabs 34 for connection to the corresponding leads of conductive 
paths of the element interconnection circuits. Element Lead Assembly 24 
and Leads 32 then pass longitudinally along Connection Side 28 of Frame 16 
toward the "back" end of Frame 16 to a location adjacent Connection 
Assembly 26, where Leads 32 turn by a first angle, such as 90.degree., in 
a direction transverse to the general longitudinal axis of Frame 16. Then, 
Element Lead Assembly 24 is bent or formed to turn by a second angle, 
again shown as 90.degree., to run along Edge Side 36 of Frame 16, again in 
the direction transverse to the general longitudinal axis of Frame 16. As 
indicated in FIG. 1, Edge Side 36 of Frame 16 is located along and abuts 
the end of the element array of Acoustic Stack 12. 
Connection Assembly 26 locates on Edge Side 36 of Frame 16 within the 
channel of Frame 16 and in the region adjacent the "back" end of Frame 16 
and, as indicated generally in FIG. 1, is provided with Connector(s) 42, 
which have pinouts corresponding to each lead of the circuit, a plurality 
of Connection Pads 38, one for each Lead 32, and each Lead 32 is 
terminated in a Cable Connection Tab 40 which is inserted into a 
corresponding Connector 42. As described above, Connection Assembly 26 is 
preferably comprised of a rigid printed circuit board to provide a rigid 
termination point for Element Lead Assembly 24 and Cable 18 and, as such, 
in a generally preferred embodiment Connection Pads 38 are comprised of 
matching Connection Pads 38 located on opposite sides of Connection 
Assembly 26 and connected by means of vias through the circuit board, with 
Leads 32 connecting to the Connection Pads 38 on one side of the circuit 
board and the corresponding wires of Cable 18 connecting to the 
corresponding Connection Pads 38 on the other side of the circuit board. 
In an alternate embodiment, the circuit board may be single sided, with 
Connection Pads 38 located on only one side of the circuit board and with 
both Leads 32 and the wires of Cable 18 connecting to Connection Pads 38 
on the same side of Connection Assembly 26. 
In an exemplary transducer, Transducer Stack 12 may be 22 mm long along 
Connection Side 28 and 12 mm long along Edge Side 36 and Frame 16 may be 
made from any material, such as aluminum, and may be 50 mm long from 
Transducer Stack 12 to its end and may be 5 mm across Connection Side 28 
and 10 mm across Edge Side 36. Element Connections 30, in turn, may have 
48, 64, 96 to 128 or any desired number of connections, with Element 
Connection 30 being spaced any desired width apart, such as 100 .mu.m to 
400 .mu.m or any desired requirement, and with a contact area, for 
example, 50 .mu.m by 300 .mu.m or any other desired dimensions. It will be 
understood, however, that such a transducer can be constructed with any of 
a wide range of lengths and widths, depending on the pitch and number of 
the elements of the transducer. 
In yet other embodiments, Connection Assembly 26 includes one or more 
Connectors 42a, one of which is shown in FIG. 1, which are mounted to the 
rigid printed circuit board of Connection Assembly 26 and connected to 
Connection Pads 38 and the Leads 32 of Element Lead Assembly 24 are 
terminated in and connected to one or more corresponding mating Connectors 
42, two of which are shown in FIG. 1, with through vias to Connector Pads 
38, which have wires of Cable 18 terminated on them to establish the 
connection between Cable 18 and the leads of Element Lead Assembly 24. In 
a typical embodiment, Connectors 42 may contain, for example, up to 50 to 
200 connector pins. 
Finally, and as described above, in the presently preferred embodiment 
Element Connection Assembly 22 will be comprised of two Element Lead 
Assemblies 24 and two Connection Assemblies 26, wherein there will be a 
Element Lead Assembly 24 and a Connection Assembly 26 on each "side" of 
Acoustic Stack 12 and Frame 16. That is, there will be a Element Lead 
Assembly 24 located on the Connection Side 28 of Frame 16 opposite that 
shown in FIG. 1, located along and abutting the opposite longitudinal side 
of the element array of Acoustic Stack 12. The second Element Lead 
Assembly 24 again includes a plurality of Leads 32, one for each 
connection to be made to a corresponding lead or conductive path of the 
element interconnection circuits of Acoustic Stack 12, which again 
terminate at the end adjoining Acoustic Stack 12 in a corresponding 
plurality of Stack Connection Tabs 34 for connection to corresponding 
leads of conductive paths of the element interconnection circuits 
accessible on the opposite side of the transducer array. The second 
Element Lead Assembly 24 and its Leads 32 then pass longitudinally along 
opposite Connection Side 28 of Frame 16 toward the "back" end of Frame 16 
to a location adjacent the second Connection Assembly 26, where Leads 32 
turn by a first angle in a direction transverse to the general 
longitudinal axis of Frame 16, such as 90.degree., and then Connection 
Assembly 24 is bent or formed to turn by a second angle, again such as 
90.degree., to run along the Edge Side 36 of Frame 16 opposite the Edge 
Side 36 shown in FIG. 1, again in the direction transverse to the general 
longitudinal axis of Frame 16. 
The second Connection Assembly 26 is likewise located in the channel of 
Frame 16 on the opposite Edge Side 36 of Frame 16, again in the region 
adjacent the "back" end of Frame 16, and is likewise provided with a 
plurality of Connection Pads 38, one for each wire of Cable 18, and is 
then connected through vias through the board to the connector wherein, 
wherein each Lead 32 is again terminated in a Cable Connection Tab 40 
which is connected to a corresponding Connector 42. Again, in the 
generally preferred embodiment the Connection Pads 38 are comprised of 
matching Connection Pads 38 located on opposite sides of Connection 
Assembly 26 with Leads 32 of Tab 40 connecting to the Connector 42 on one 
side of the circuit board and the corresponding wires of Cable 18 
connecting to the corresponding Connection Pads 38 on the other side of 
the circuit board. In the alternate embodiments, again, the circuit board 
may be single sided, with both Leads 32 and the wires of Cable 18 
connecting to Connection Pads 38 on the same side of Connection Assembly 
26, or may be provided with Connectors 42a and 42b for connecting Leads 32 
to the wires of Cable 18. 
In this regard, it is shown in FIG. 1 that, in the embodiment having a 
Connection Assembly 26 on either side of Frame 16, Cable 18 is divided 
into two Wire Groups 44 of wires near the end of Cable 18 close to Frame 
16 and the wires of each Wire Group 44 are connected to a respective one 
of Connection Assemblies 26. It is also shown that the wires of each Wire 
Group 44 are essentially colinear with the axis of Frame 16 as they 
approach Frame 16 and that the wires of each Wire Group 44 are then 
dressed, or turned, through 90.degree. to be attached to the Connector 
Pads 38 of Connector Assembly 26. The longitudinal axis of Connector 42b, 
like that of mating Connector 42a, thereby lies parallel to the 
longitudinal axis of Frame 16 so that the connection between Connection 
Assembly 26 and Cable 18 is relatively narrow and thereby allows easier 
handling of Transducer 10 by a user. 
In yet other embodiments, requiring fewer connections between the elements 
of Transducer Stack 12 and Transducer Electronics 20, only a single 
Connection Assembly 26 is necessary for the required number of connections 
and Cable 18 is not divided into two Wire Groups 44; otherwise, the 
connection between Cable 18 and Connection Assembly 26 is the same as just 
described, with the wires of Cable 18 being dressed through 90.degree. 
before connection to a Connector 42b or Connection Pads 38. 
Also, in certain embodiments Element Lead Assembly 24 may not be turned 
through the second 90.degree. angle and parallel to the longitudinal axis 
of Frame 16 to bring Cable Connection Tabs 40 onto Edge Side 36 of Frame 
16, so that Cable Connection Tabs 40 and Connectors 42, if used, are 
located on the Connection Sides 28 of Frame 16, possibly adjacent Edge 
Sides 36. 
In still further embodiments, a Transducer Stack 12 may have Element 
Connections 30 on one or more ends of the Transducer Stack 12, as well as 
on the sides, and there may be Element Lead Assemblies 24 located on one 
or more Edge Sides 36 of Frame 16 as well as on Connection Sides 28. In 
these cases, the additional Connection Assemblies 26 for the Edge Side 36 
Element Lead Assemblies 24 may be located on their Edge Sides 36, in the 
manner just described, or the Element Lead Assemblies 24 may turn through 
90.degree. so that their Connection Assemblies 26 are located on the 
respective Connection Sides 28. 
Lastly, it is shown in FIG. 1 that Transducer 10 includes a Wire Cap 46 to 
cover and protect each Connection Assembly 26 and the connections of 
Element Lead Assembly 24 and Cable 18 to Connection Assembly 26. 
Referring now to FIG. 2, therein is shown a diagrammic representation of 
Element Lead Assembly 24. As shown therein, Element Lead Assembly 24 is 
unfolded during its creation, but is folded before attachment to Element 
Connections 30. Element Lead Assembly 24 includes a plurality of Leads 32, 
one for each connection to be made to a corresponding lead or conductive 
path of the element interconnection circuits of Acoustic Stack 12, which 
terminate at Transducer End 48 of Element Lead Assembly 24 adjoining 
Acoustic Stack 12 in a corresponding plurality of Stack Connection Tabs 34 
for connection to Element Connections 30 of the corresponding leads or 
conductive paths of the element interconnection circuits of Transducer 
Stack 12. It will be noted that Transducer End 48 of Element Lead Assembly 
24 is equal to the width of Element Connections 30 wherein Stack 
Connection Tabs 32 are connected to Element Connections 30 and narrows to 
the width of Connection Side 28 of Frame 16, thereby allowing additional 
width for bonding or attachment of Element Lead Assembly 24 to Backing 14 
in the area of Element Connections 30. In a typical embodiment, each of 
Connection Tabs 34 may be 50 .mu.m or more wide by 1.2 mm or more long and 
a center to center spacing as necessary for a particular design, such as, 
420 .mu.m. 
It will be noted that Leads 32 are spaced apart from one another in the 
area adjacent Connection Tabs 34 by the distance necessary to align 
Connection Tabs 34 with Element Connections 30 and to allow the maximum 
widths for Connection Tabs 34 and Element Connections 30. Leads 32 then 
pass longitudinally along Connection Side 28 of Frame 16 toward the "back" 
end of Frame 16, and in doing so may first pass through a Width Transition 
Zone 50 wherein the spacing between Leads 32 is reduced from the spacing 
in the area of Connection Tabs 34 to a spacing sufficient for electrical 
isolation between Leads 32. A Width Transition Zone 50 may not be 
necessary, or preferable, however, depending upon the number and required 
minimum spacing between Leads 32 and the width available across Connection 
Side 28 of Frame 16 for Element Lead Assembly 24 in its folded 
configuration. In a typical embodiment, Leads 32 will be may be 102 .mu.m 
wide in Width Transition Zone 50, and may be spaced 102 .mu.m apart while 
Width Transition Zone 50 may have a length along Frame 16 as necessary for 
the particular design, such as 12 mm. 
The area of Element Lead Assembly 24 between Width Transition Zone 50 and 
the end of Frame 16 is of increased width and is divided into two Lead 
Zones 52a and 52b wherein Leads 32 are divided into two Groups 54a and 54b 
that are spaced apart from one another and are routed through Lead Zones 
52a and 52b, respectively. The Leads 32 of each of Groups 54a and 54b then 
turn through 90.degree. in the direction transverse to the general 
longitudinal axis of Frame 16, with the Leads 32 of Group 54a pass across 
the area of Lead Zone 52b in parallel with the Leads 32 of Group 54b to 
pass into a Lead Zone 52c extending transversely to Lead Zone 52b wherein 
each Lead 32 is terminated in a Cable Connection Pad 40. 
As has been described above, and as illustrated in FIG. 4, Lead Assembly 24 
and, in particular the area of Element Lead Assembly 24 comprising Lead 
Zone 52c, is then turned through a second 90.degree. angle along a Corner 
Line 56 parallel to the longitudinal axis of Frame 16 and in the area 
between the 90.degree. turn of Leads 32 and Cable Connection Tabs 40 to 
run along Edge Side 36 of Frame 16 so that Cable Connection Tabs 40 are 
located on Edge Side 36 of Frame 16. 
It has been described above and as illustrated in FIG. 4, that Element Lead 
Assembly 24 is folded over on itself along an axis parallel to the 
longitudinal axis of Frame 16, indicated in FIG. 2 as Fold Line 58, 
thereby significantly reducing the width of Element Lead Assembly 24 along 
Frame 16. In this regard, and for this purpose, it is shown in FIG. 2 that 
while Group 54a is generally colinear with its Leads 32 in the area of 
Width Transition Zone 50 and Connection Tabs 34, Group 54b is not colinear 
with its Leads 32 in the area of Width Transition Zone 50 and Connection 
Tabs 34 and is offset with respect to Group 54a. The distance between Lead 
Zones 52a and 52b with Groups 54a and 54b, and the widths of the regions 
of Element Lead Assembly 24 occupied by Lead Zones 52a and 52b with Groups 
54a and 54b, are selected such that Element Lead Assembly 24 may be folded 
along Fold Line 58, which passes along the space between Lead Zones 52a 
and 52b, so that Group 54b will generally overlay Group 54b, so that Outer 
Edge 60 of Element Lead Assembly 24 does not overlap Cable Connection Tabs 
40 or extend past Corner Line 56, and so that the width of the folded 
Element Lead Assembly 24 between Fold Line 58 and Corner Line 56, or in an 
alternate embodiment described below, Cable Connection Tabs 40, falls 
within the width of Connection Side 28 of Frame 16. 
It will be noted that in an alternate embodiment of the present invention, 
as mentioned previously, Element Lead Assembly 24 may not be turned 
through a second 90.degree. angle along Corner Line 56 parallel to the 
longitudinal axis of Frame 16 so that Cable Connection Tabs 40 are located 
on Edge Side 36 of Frame 16. In this embodiment, Cable Connection Tabs 40, 
and Connectors 42a may be located on Connection Side 28 of Frame 16, 
possibly adjacent Edge Side 36, and, in this embodiment, the distance 
between Lead Zones 52a and 52b with Groups 54a and 54b, and the widths of 
the regions of Element Lead Assembly 24 occupied by Lead Zones 52a and 52b 
with Groups 54a and 54b, are selected such that Outer Edge 60 of Element 
Lead Assembly 24 does not overlap Cable Connection Tabs 40. 
It will also be understood by those of ordinary skill in the relevant arts 
that Groups 54 need not all include the same number of Leads 32, and that 
the Leads 32 in the Groups 54 may be provided for different uses and 
functions. For example, certain Leads 32 may carry bias voltages or ground 
connections while others may carry signals, and the Leads 32 may be 
grouped or distributed accordingly. In addition, and in those embodiments 
having more than one Element Lead Assembly 24 and Connection Assembly 26, 
the uses and functions of the Leads 32 of the Element Lead Assemblies 24 
and Connection Assemblies 26 may differ. For example, and again, bias 
voltages or grounds may be carried in only one of the Element Lead 
Assemblies 24 or the Element Lead Assemblies 24 may have different numbers 
of Leads 32, as may the two Wire Groups 44. 
In yet other embodiments of the present invention, Leads 32 may be divided 
into three or more Lead Zones 52, each with a Group 54 of Leads 32 wherein 
each Lead Zones 52 with its Group 54 is spaced apart from the other Lead 
Zones 52 with their Groups 54 in the manner described above and wherein 
the Leads 32 of each Group 54 are again turned through 90.degree. before 
being terminated in a Cable Connection Pad 40 and wherein Element Lead 
Assembly 24 is again turned through a second 90.degree. angle along Corner 
Line 56 so that Cable Connection Tabs 40 are located on Edge Side 36 of 
Frame 16. In this embodiment, there will again be Fold Lines 58 between 
Lead Zones 52 and the Element Lead Assembly 24 will be accordion folded 
along the Fold Lines 58 so that the folded Element Lead Assembly 24 
assumes the configuration along Connection Side 28 described above. Again, 
in those implementations having more than one Element Lead Assembly 24, 
the Element Lead Assemblies 24 need not have the same number of Lead Zones 
52 and Groups 54 or Connectors 42. 
Finally referring to FIG. 3, it is shown therein that in a presently 
preferred embodiment of the present invention Element Lead Assembly 24 is 
comprised of a multilayer flexible circuit having a Base Layer 62, a Trace 
Layer 64 in which Leads 32 are formed, an Isolation Layer 66 and a Ground 
Layer 68 wherein, and for example, Base Layer may be comprised of polymide 
approximately 1 mil thick, Trace Layer 64 may be comprised of copper 
approximately 1.4 mils thick and Ground Layer 68 may be comprised of 
copper and approximately 1.4 mils thick. Element Lead Assembly 24, and 
indicated generally in FIG. 3, may also include Stiffeners 70 in the 
region of Cable Connection Tabs 40 wherein Stiffeners 70 may be comprised 
of polymide chosen such that the total thickness in this area is 12 mils 
(0.3 mm) thick. 
It will be understood by those of ordinary skill in the relevant arts from 
the above descriptions that the element connection assembly of the present 
invention provides a smaller and more easily manipulated handle by which a 
user may manipulate and use the transducer and a more robust and better 
protected assembly and connection between the transducer and the cable 
connecting to the transducer electronics that will be less prone to 
breakage or damage in use. In addition, the element connection assembly of 
the present invention allows the cable to be readily attached and detached 
and provides easier assembly during manufacture and easier repair with 
reduced risk of damage to the element lead assembly, the element 
connection assembly and the cable. 
Lastly, while the invention has been particularly shown and described with 
reference to preferred embodiments of the apparatus and methods thereof, 
it will be also understood by those of ordinary skill in the art that 
various changes, variations and modifications in form, details and 
implementation may be made therein, as has been discussed herein above, 
without departing from the spirit and scope of the invention as defined by 
the appended claims.