Patent Description:
Sonar (SOund Navigation And Ranging) is used to detect waterborne or underwater objects. For example, sonar devices may be used to determine depth and bottom topography, detect fish, locate wreckage, etc. Sonar transducer elements, or simply transducers, convert electrical energy into sound or vibrations at a particular frequency. A sonar sound beam is transmitted into and through the water and is reflected from objects it encounters. The transducer receives the reflected sound (the "sonar returns") and converts the sound energy into electrical energy. Based on the known speed of sound, it is possible to determine the distance to and/or location of the waterborne or underwater objects. The sonar return signals can also be processed to be displayed on a display device, giving the user a "picture" of the underwater environment.

Applicant herein provides improved techniques and assemblies for producing sonar transducer assemblies.

Sonar transducer assemblies may be formed, in some cases, using one or more transducer elements that are installed or mounted in mechanical and electrical contact with a printed circuit board (PCB). The transducer elements may be soldered to the electrical contact pads on the PCB. The PCB is an elastic wave bearing structure. Acoustic transducer elements, such as used in sonar systems, attached to the PCB are, in general, points of coupling incoming sound from the environment into the various elastic wave types supported by the PCB. The elastic waves, so excited, may propagate in all directions within the PCB, scattering from the various boundaries and attached structures (e.g. discrete electrical components), leading to a frequency- and location-dependent feedback to the transducer elements. The electrical output of the transducer elements can be, therefore, a combination of direct acoustic stimulation by the incoming sound plus indirect stimulation due to feedback through the elastic structure of the PCB. For brevity, the term "elastic response" shall be used to refer to the unwanted feedback from the structure to which the transducer elements are attached.

When, for the purpose of producing an array of spatially-arranged receivers or transmitters, more than one transducer element is placed in a sonar system, it is desirable, in order to effectively apply simple beamforming algorithms, that the electrical signals transduced by the transducer elements be uniform simple functions of the acoustic field that they are intended to sample (in the case of receiving) or produce (in the case of transmitting). Physical connections between the transducer elements and the PCB may not only produce an undesired signal involving the PCB as an elastic wave-bearing medium, but the mechanical impedance of the connections may also have a local effect on the frequency response of the transducer elements, e.g. mass loading by solder at the attachment points of the transducer elements. Inconsistencies in the mechanical boundary conditions at the point of electrical connections in addition to the elastic response of the PCB may cause undesired, chaotic electrical signals to be produced by the transducer elements, which may, for example, degrade the sonar image.

Embodiments of the present invention contemplate a flex tab arrangement for the PCB of a sonar transducer assembly. Such a flex tab arrangement may mitigate the undesired signals caused by the elastic response of the PCB. Additionally, the element-to-element variations across the transducer assembly caused by inconsistencies in the mechanical boundary conditions due to inconsistent solder joints may be mitigated by removing the solder connection altogether.

According to the invention, the PCB includes a pair of flexible electrical connection tabs for each transducer element, e.g. piezoelectric crystal. The transducer element is inserted into a section of the PCB between the flex tabs, thereby causing the flex tabs to flex outwardly from a plane defined by the PCB. Flexion of the flex tabs outwardly of the PCB plane causes an elastic force on each of the flex tabs to be applied to opposing ends of the transducer elements to create an electrical connection. In some embodiments, the flexion of the flex tabs may mechanically isolate the ends of the transducer elements from the PCB, thereby mitigating or eradicating interference from the elastic response of the PCB.

In this regard, according to the invention, the transducer elements are not affixed, such as by solder or adhesive, to the PCB. Instead, the force applied by the flex tabs on opposing ends of the installed transducer element is sufficient to maintain the position of the transducer element as well as maintain an electrical connection to the transducer element. The removal of the solder connection to the PCB may further eliminate transference of the resonance waves from the transducer elements to the PCB. Further, removal of the solder connection may also remove inconsistences in the mechanical boundary conditions of the electrical connections to the transducer elements, thereby reducing element-to-element variations across the transducer assembly and, in some cases, increasing the sharpness of the sonar image.

It is known from <CIT> to provide a sonar transducer assembly comprising a transducer element and a flexible printed circuit board comprising at least one set of electrical connections, and a support structure having an aperture to retain the transducer element. The invention is defined by the appended apparatus claim <NUM> and method claim <NUM>.

Preferred features of the invention are defined in the dependent claims.

Exemplary embodiments of the present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

<FIG> illustrates an example transducer assembly <NUM>. The transducer assembly <NUM> may include a printed circuit board (PCB) <NUM> and a plurality of transducer elements <NUM> arranged in an array. Each of the transducer elements <NUM> may be a piezoelectric crystal that is surface mounted to the PCB <NUM>. In some embodiments, each of the transducer elements <NUM> may be directly affixed to the PCB <NUM>, such as by a solder joint <NUM>. The transducer elements <NUM> may each have one or more conductive surfaces, such as at each end of the transducer element. The conductive surface of the transducer element may be soldered to a conductive pad disposed on the surface of the PCB <NUM>.

In some cases, the solder joints <NUM> may cause non-uniformity of the mechanical boundary conditions at the electrical contacts for each transducer element <NUM> of the transducer array <NUM>. For example, the non-uniformity may be caused by the adhesion of the solder to the transducer element <NUM> and/or the conductive surface on the PCB <NUM>, variations in the amount of solder material in the solder joint <NUM>, variations in the distribution of the solder material in the solder joint <NUM>, impurities in the solder joint <NUM>, or the like. In some cases, affixing the transducer elements <NUM> to a face of the PCB <NUM> may enable translation, or transfer, of resonate vibrations of the transducer elements <NUM> to the PCB <NUM> causing an elastic response, e.g. resonance waves <NUM>. For example, formed resonance waves <NUM> may propagate across a substrate of the PCB <NUM> and reflect off one or more edges, or boundaries, of the substrate, thereby causing further elastic response, e.g. reflection waves. The resonance waves <NUM> and associated reflections may cause vibrations in the transducer elements <NUM>, which may ultimately form undesirable signals, e.g. interference, in the sonar signals.

In some cases, the PCB <NUM> may include a first layer PCB and a second layer PCB. The first layer of the PCB <NUM> may be disposed on a first side of the transducer element and the second layer of the PCB may be disposed on the second side of the transducer element. Each of the first layer and second layer of the PCB <NUM> may include a conductive pad, such that the transducer element <NUM> is connected at a first end to the conductive pad of the first layer of the PCB <NUM> and connected at a second end to a conductive pad of the second layer of the PCB <NUM>. In such a manner, the transducer element(s) may be "sandwiched" between the first layer and second layer of the PCB <NUM>. Such a two layer assembly may result in some reduction of the translation of the elastic response, e.g. resonate vibrations of the transducer elements <NUM>. However, the solder joints <NUM> or other methods of affixing of the transducer elements <NUM> to the PCB <NUM> may also have significant translation of resonate vibrations therebetween.

Some embodiments of the present invention contemplate various transducer assemblies that reduce the variations in mechanical boundary conditions within the transducer assembly, such as may be formed based on the mechanical connections between the transducer elements and a PCB, thereby reducing element-to-element variations across the transducer assembly and, in some cases, increasing the sharpness of the sonar image. In some embodiments, example transducer assemblies described herein may also reduce translation of the resonate vibration of the transducer elements to the substrate of the PCB, thereby mitigating or eradicating interference from the elastic response of the PCB.

<FIG> and <FIG> each illustrate an example printed circuit board (PCB) <NUM> in accordance with some embodiments discussed herein. The PCB <NUM> may include a flexible substrate <NUM>, such as a Mylar film or other suitable material, and two or more conductive traces <NUM>, such as copper traces or other suitable conductive material. The flexible substrate <NUM> may encapsulate the conductive traces <NUM>, with the exception of contact pads <NUM> as discussed below, providing electrical insulation to the conductive traces <NUM>. The body of the PCB <NUM> may be defined as the portion of the PCB <NUM> including electrical connections and circuit components other than the off board circuit traces.

The conductive traces <NUM> may be connected at one end to a flexible element tab, e.g. flex tab <NUM>. In some embodiments, a contact pad <NUM> may be formed on the flex tab <NUM> and configured to interact with an end of the transducer element (such as described herein). In some such embodiments, the conductive traces <NUM> may be connected to the contact pads <NUM>, such as to ultimately be electrically connected to an installed transducer element. In some embodiments, the contact pads <NUM> may be electrically conductive. Additionally or alternatively, conductive traces <NUM> may pass through the contact pads <NUM> so as to be electrically connected to an installed transducer element.

The flex tabs <NUM> may be attached at one or more ends (e.g., end <NUM>) to a body <NUM> of the PCB <NUM> that defines a PCB plane. Additionally, one or more other ends or sides (e.g., sides <NUM>, <NUM> and end <NUM>) may be unattached to a body of the PCB <NUM> for at least a portion of the periphery of the flex tab <NUM> thereby enabling flex tabs <NUM> to flex, e.g. bend, outwardly from a PCB plane defined by the body of the PCB <NUM>. In some embodiments, one end <NUM> and sides <NUM>, <NUM> of the flex tabs <NUM> may be dye cut, laser cut, or otherwise detached from the body of the PCB <NUM>. The flexible substrate a <NUM> and conductive traces <NUM> may bend or flex at the junction of the attached side <NUM> of the flex tab <NUM> and the body of the PCB <NUM>.

The conductive pads <NUM> of the flex tabs <NUM> may be formed of any suitable conductive material of high conductance, such as gold, silver, copper, non-metallic conductors, or the like. The conductive pads <NUM> may be formed of the same material as the conductive traces <NUM>, such as by acid etching or other suitable method. The conductive pads <NUM> may be an extension of the conductive traces <NUM> that are not covered by the flexible substrate <NUM>, such that the conductive pads <NUM> may be in direct contact with an end of a transducer element <NUM>, such as illustrated conceptually in <FIG>.

In an example embodiment, with reference to <FIG>, the flex tabs <NUM> may be disposed as a flex tab pair including a first flex tab 202A and a second flex tab 202B. The flex tab pair 202A, 202B may have attached ends <NUM> disposed at a far end from the unattached end <NUM>, such that when the flex tabs <NUM> flex out of the PCB plane. In some embodiments, the flex tab pair 202A, 202B are configured to flex away from each other. The transducer element <NUM> is inserted, or installed into an opening <NUM> created by flexion of the flex tabs 202A, 202B outwardly from the PCB plane. The transducer element <NUM> may include a first conductive element (e.g., portion) 350A disposed at a first end of the transducer element <NUM> and a second conductive element (e.g., portion) 350B disposed at a second end of the transducer element <NUM> (in some embodiments, the entire or different portions of the transducer element may be conductive). When installed into the PCB <NUM> (such as illustrated in <FIG>) flexion of the flex tab pair 202A, 202B causes the first flex tab 202A to generate a reactionary elastic force in the direction of the second flex tab 202B and the second flex tab 202B to generate a reactionary elastic force in the direction of the first flex tab 202A. The elastic force may cause the first conductive pad 205A of the first flex tab 202A to contact the first conductive element 350A of the transducer element <NUM> and the second conductive pad 205B of the second flex tab 202B to contact the second conductive element 350B of the transducer element <NUM>. The contact between the first conductive pad 205A with the first conductive element 350A and the second conductive pad 205B with the second conductive element 350B may create an electrical path across the flex tab pair 202A, 202B and the transducer element <NUM>.

In some embodiments, one or more of the contact pads <NUM> on the flex tabs <NUM> may include a point contact <NUM>. For example, with reference to <FIG>, a first point contact 207A is disposed on the first flex tab 202A and a second point contact 207B is disposed on the second flex tab 202B. The point contacts may each extend outwardly away from the corresponding flex tab <NUM> toward the transducer element <NUM>, when installed in the PCB <NUM>, such as depicted in <FIG> and <FIG>. In an example embodiment, the point contacts may be a set of dimples. The dimples may be formed on the contact pad <NUM> by warping the substrate <NUM> and contact pad <NUM>, such as by applying force to a dye in contact with the contact pad <NUM>. Alternatively, the point contacts <NUM> may be formed by adding a predetermined amount of conductive material, e.g. solder, to a portion of the conductive pad <NUM>. In some embodiments, the predetermined amount of conductive material may have a precise mass load for each application to ensure uniformity.

As described in further detail below, a transducer element <NUM> may be installed in a direction perpendicular to the PCB plane causing the flex tabs <NUM> to flex (e.g., in some cases, further flex) outwardly from the PCB plane. The flexion of the flex tabs <NUM> causes an elastic force of the flex tabs <NUM> to be applied against opposing ends of the transducer elements <NUM>. The point contact <NUM> on the conductive pad <NUM> of the flex tab <NUM> may increase the pressure applied by the flex tabs <NUM> by reducing the contact area between the conductive ends <NUM> of the transducer elements <NUM> and the conductive pads <NUM> of the flex tabs <NUM>. More particularly, when installed into the PCB <NUM>, flexion of the flex tab pair 202A, 202B causes the first flex tab 202A to generate a reactionary elastic force in the direction of the second flex tab 202B and the second flex tab 202B to generate a reactionary elastic force in the direction of the first flex tab 202A. The elastic force may cause the first point contact 207A of the first conductive pad 205A of the first flex tab 202A to contact the first conductive element 350A of the transducer element <NUM> and the second point contact 207B of the second conductive pad 205B of the second flex tab 202B to contact the second conductive element 350B of the transducer element <NUM>. The contact between the first conductive pad 205A with the first conductive element 350A (e.g., through the first point contact 207A) and the second conductive pad 205B with the second conductive element 350B (e.g., through the second point contact 207B) may create an electrical path across the flex tab pair 202A, 202B and the transducer element <NUM>.

In some embodiments, with reference to <FIG>, the PCB <NUM> may include one or more alignment apertures <NUM> configured to aid in alignment of the PCB <NUM> during assembly of the transducer assembly and/or receive one or more fasteners, such as screws, to mount the PCB to another component of the transducers assembly.

<FIG> illustrate example insertion of a transducer element <NUM> into a PCB <NUM> with flex tabs <NUM> in accordance with some example embodiments of a transducer assembly <NUM> discussed herein. Each of the transducer elements <NUM> may be a piezoelectric crystal, such as a length-poled piezoelectric crystal, configured to emit sound waves when excited by an electrical signal and/or emit an electrical signal when excited by a vibration, such as a sound wave. The transducer elements <NUM> may include conductive elements <NUM> disposed on opposing ends of the transducer elements <NUM>, as discussed above in reference to <FIG>. The conductive elements <NUM> may be formed by any suitably high conductance material, such as gold, silver, copper, non-metallic conductors, or the like.

The transducer assembly <NUM> includes one or more support structures <NUM>. The support structure <NUM> includes an aperture <NUM> configured to receive at least a portion of the transducer element <NUM>. Additionally, the support structure <NUM> is also configured to support the body of the PCB <NUM> while allowing flexion of the flex tabs <NUM> into the aperture <NUM>.

The PCB <NUM> may be aligned and/or mounted to the support structure <NUM>. The transducer element <NUM> may be press fit into the aperture <NUM> of the support structure <NUM> causing the flex tabs <NUM> to flex outwardly from the PCB plane <NUM> into the aperture <NUM>. Flexion of the flex tabs <NUM> cause a reactionary elastic force to be applied to the conductive elements <NUM> disposed at the ends of the transducer elements <NUM>. With the transducer elements <NUM> installed, the flex tabs <NUM> may be approximately perpendicular, e.g. <NUM> degrees from, the body of the PCB <NUM>. In some embodiments, the mounting of the transducer element <NUM> into the support structure <NUM> and/or PCB <NUM> may be through an interference fit.

The flexion or bend in the flex tab <NUM> may prevent or limits resonate vibration translated from the transducer elements <NUM> to the flex tabs from propagating across the body of the PCB <NUM> as resonance waves, thus also preventing or limiting reflected waves. The reduction or elimination of the resonance waves may be caused by a resistance, or inefficacy, of the resonate vibration to shift mode approximately <NUM> degrees from the flex tab <NUM> to the body of the PCB <NUM>. Additionally, in some embodiments, since each transducer element <NUM> is installed between a separate set of flex tabs <NUM>, the resistance to propagation of the resonate vibration from the flex tabs <NUM> to the body of the PCB <NUM> may also prevent vibrations caused by one transducer element <NUM> from reaching a second transducer element. This reduction in the elastic response, e.g. resonance waves and reflected waves, may significantly reduce undesirable signals, e.g. interference, that may otherwise effect the sonar image.

In some embodiments, the translation of the resonate vibration, e.g. resonance waves, may be further reduced by the electrical connection between the transducer elements <NUM> and the conductive pads <NUM> of the PCB <NUM>. In this regard, since the electrical connection is made by contact between the conductive pads <NUM> of the PCB <NUM> and the conductive elements <NUM> on the transducer elements <NUM> caused by the elastic force, solder or other fixation of the transducer elements <NUM> to the PCB <NUM> is not necessary. The lack of direct mechanical connection, such as the solder joint <NUM> of the prior art, may significantly reduce translation of the resonate vibrations to the PCB <NUM>. Another advantage of the lack of solder joints is the removal of variations in mechanical boundary conditions of the electrical connections caused by the solder joint, which may result in a sharper sonar image due to clearer and/or stronger signals to and from the transducer elements <NUM>.

<FIG> illustrates a perspective view of an example transducer assembly <NUM> in accordance with some example embodiments discussed herein. The transducer assembly <NUM> may include a plurality of transducer elements <NUM> inserted or mounted into the PCB <NUM> between flex tabs <NUM>. The transducer assembly <NUM> may be assembled and aligned by an assembly fixture <NUM>, as discussed below in reference to <FIG>. <FIG> illustrates a cross sectional view of a transducer assembly <NUM> in accordance with some example embodiments discussed herein. The transducer assembly may include a base foam <NUM>, a support structure <NUM> middle foam <NUM>, PCB <NUM>, a top foam <NUM>, and a plurality of transducer elements <NUM>. The interaction of the various components of the transducer assembly <NUM> are discussed below in reference to <FIG>.

<FIG> illustrates an exploded view of a portion of the transducer assembly <NUM> in accordance with some example embodiments discussed herein. The transducer assembly <NUM> may include a middle foam <NUM>, e.g. a flex foam, in addition to the support structure <NUM> (shown in <FIG>). The middle foam <NUM> may include an aperture <NUM> (depicted in <FIG>) to receive the transducer elements <NUM> and the flex tabs <NUM> of the PCB <NUM>. In some example embodiments, the middle (or other) foam may serve as the support structure supporting the body of the PCB <NUM> and the support structure <NUM> may not be provided.

The middle foam <NUM> may be any nonconductive material with a high elasticity and low creep, such as closed cell foam, rubber, or the like. The middle foam <NUM> may have separate apertures <NUM> for each transducer element <NUM>, to provide individual enclosures for each transducer element <NUM>. In some embodiments, the aperture <NUM> may be smaller than or the same size as the transducer elements <NUM> in the longitudinal direction of extension, such that when the flex tabs <NUM> flex into the aperture <NUM> and contact the edge of the aperture, the foam resists the flexion of the flex tabs <NUM>. The resistance to the flexion of the flex tabs <NUM> may cause an increase in force (e.g., a resistance force) to be applied by the flex tabs <NUM> to the conductive elements <NUM> at the ends of the transducer elements <NUM>.

In some embodiments, the apertures <NUM> may be formed by an H cut, such that the middle foam <NUM> includes a plurality of foam tabs <NUM> configured to flex outwardly from a foam plane <NUM> defined by the body of the middle foam. The foam tabs <NUM> may flex with the flex tabs <NUM> into the aperture <NUM> (depicted in <FIG>) in the support structure <NUM> and/or the base foam <NUM>. Flexion of the foam tabs <NUM> may cause an elastic force to be applied to the flex tabs <NUM>, thereby causing an increase in the total force applied by the flex tabs <NUM> to the ends of the transducer elements <NUM>.

<FIG> and <FIG> illustrate exploded views of the transducer assembly <NUM> in accordance with some example embodiments discussed herein. In some example embodiments, the assembly fixture <NUM> may include one or more guide posts <NUM> or ribs which may be received through one or more guide holes <NUM> or notches disposed in the top foam <NUM>, middle foam <NUM>, support structure <NUM>, and/or the base foam <NUM>. The one or more guide posts <NUM> may be further received through one or more guide holes <NUM> of the PCB <NUM>. The guide posts <NUM> may be metal, plastic, or other suitably rigid material. The guide posts <NUM> may project upward and away from an assembly face of the assembly fixture <NUM>. The guide post <NUM> and guide holes <NUM>, <NUM> may align the components of the transducer assembly <NUM> during assembly. In some embodiments, the guide holes <NUM>, <NUM> may also be used to mount and/or align the transducer assembly <NUM> in a housing, such as the transducer assembly housing <NUM> illustrated in <FIG>. Additionally or alternatively, the transducer assembly housing <NUM> or other close tolerance container may be utilized to align the various components of the transducer assembly <NUM> during the assembly process, such as described below in reference to <FIG>.

The transducer assembly <NUM> may include a top foam <NUM> and a base foam <NUM> disposed on opposing faces of the middle foam <NUM> (e.g., the top foam <NUM> and base foam <NUM> may "sandwich" the middle foam <NUM>). The top foam <NUM>, middle foam <NUM>, and base foam <NUM> may absorb sound waves which are not aligned with the acoustic, e.g. emitting face, of the transducer elements <NUM> of the transducer assembly <NUM>. Additionally, the top foam <NUM>, middle foam <NUM>, and/or the base foam <NUM> may dampen radiative sound waves produced by vibration of the transducer elements <NUM>. The base foam <NUM> may include a plurality of apertures <NUM> corresponding to each to the transducer elements <NUM> to provide an unobstructed path for emitted and received sound waves to the acoustic face of the transducer assembly <NUM>. Additionally, as discussed above, the apertures <NUM> in the base foam <NUM> may receive a portion of the flex tabs <NUM> and/or the foam tabs <NUM> when they are flexed outwardly from the PCB plane <NUM> and foam plane <NUM> (shown in <FIG>), respectively.

The support structure <NUM>, e.g. crystal chassis, may be formed of plastic, rubber, or other suitable ridged, or semi-rigid material (although, in some embodiments, the term "support structure" may refer to one or more foam layers, such as may be used to replace a rigid support structure). The support structure <NUM> may include a single aperture <NUM> or a plurality of apertures to receive the individual transducer elements <NUM>. The support structure <NUM> may include a single aperture <NUM> in an embodiment including a middle foam <NUM> or other component providing lateral separation of the transducer elements <NUM>, to prevent undesirable signals, e.g. interference, caused by contact between vibrating piezoelectric crystals. The support structure <NUM> may be disposed between the base foam <NUM> and the middle foam <NUM>, and the PCB <NUM> may be disposed between the support structure <NUM> and the top foam <NUM>.

In some example embodiments, the support structure may include one or more retention clips <NUM>. The retention clips <NUM> may project away from the surface of the support structure <NUM>. The retention clips <NUM> may be configured to receive and retain a chassis front <NUM> (<FIG>) in a predetermined position. The top foam <NUM>, PCB <NUM>, and middle foam <NUM> may be "sandwiched" between the support structure <NUM> and the chassis front <NUM>, which may cause a force to be applied between the middle foam <NUM>, PCB <NUM>, and top foam <NUM>, thereby limiting or preventing voids therebetween.

The top foam <NUM> may include an aperture <NUM> configured to receive an expansion foam. The aperture <NUM> may extend in a longitudinal direction of extension of the top foam <NUM>. The aperture <NUM> may expose the transducer elements <NUM> when the transducer assembly <NUM> is assembled. The expansion foam may be poured through the aperture <NUM> around the transducer elements and into the apertures <NUM> of the PCB <NUM>, the aperture <NUM> of the middle foam <NUM>, the aperture <NUM> of the support structure <NUM>, and the aperture <NUM> of the base foam <NUM> - filling voids between the components. The expansion foam may harden to affix or "lock" the position of the transducer elements <NUM> relative to the other components of the transducer assembly <NUM>. Notably, however, the expansion foam does not mechanically affix the transducer element to the PCB <NUM> or any other component of the transducer assembly <NUM>.

<FIG> illustrates the transducer assembly <NUM> within a transducer assembly housing <NUM> in accordance with some example embodiments discussed herein. The transducer assembly <NUM> may be assembled and installed into the transducer assembly housing <NUM>, such as described below. The transducer assembly housing <NUM> may provide structural support and protection of the transducer assembly <NUM> in a marine environment. In some embodiments, the transducer assembly housing <NUM> may be watertight, shock resistant, or the like. The transducer assembly housing <NUM> may be configured to house one or more transducer assemblies <NUM> and/or one or more sensors, such as position sensors, temperature sensors, water flow sensors, acoustic sensors, or the like.

<FIG> and <FIG> illustrate a flow chart of a method of assembling the transducer assembly in accordance with some example embodiments discussed herein. In some embodiments, the method may include additional, optional operations, and/or the operations described below may be modified or augmented. In an example embodiment, the method may include installing a release film onto the fixture assembly <NUM> at operation <NUM>. The release film may be a polyurethane sheet, or other suitable material, which may enable the expansion foam or other materials to be set within the transducer assembly without adhesion to the assembly fixture <NUM>. Additionally, the release film may be removed relatively easily, such as by peeling, from the transducer assembly <NUM> (e.g., after the transducer assembly <NUM> is removed from the assembly fixture <NUM>).

The method may include cutting flex holes, e.g. apertures <NUM>, into the base foam <NUM> at operation <NUM> and cutting flex holes, e.g. apertures <NUM>, into the middle foam <NUM> at operation <NUM>. As depicted in <FIG>, the number and arrangement of the apertures <NUM>, <NUM> may correspond to the number and arrangement of the transducer elements <NUM>. The apertures <NUM> of the middle foam <NUM> and/or apertures <NUM> of the base foam <NUM> may be cut in an H pattern, e.g. H cut, thereby forming foam tabs <NUM>. The cuts may be executed by a dye, laser, knife, or other suitable cutting tool.

At operation <NUM>, the base foam <NUM> may be mounted to the assembly fixture <NUM>. As depicted in <FIG>, guide holes <NUM> of the base foam may be fitted onto guide posts <NUM> of the assembly fixture <NUM>. Additionally or alternatively, the transducer housing <NUM> or other close tolerance container may be utilized to align the various components of the transducer assembly <NUM> during the assembly process.

At operation <NUM>, the crystal chassis, e.g. support structure <NUM>, may be mounted to the assembly fixture <NUM>. At operation <NUM>, the middle foam <NUM> may be mounted to the assembly fixture <NUM>. At operation <NUM>, the flex PCB <NUM> may be mounted to the assembly fixture <NUM>. Each of the support structure <NUM>, middle foam <NUM>, and PCB <NUM>, may include guide holes <NUM>, <NUM> that fit onto the guide posts <NUM>. Additionally or alternatively, the support chassis <NUM> may include one or more alignment protrusions <NUM>, depicted in <FIG>, corresponding to one or more alignment recesses <NUM>, depicted in <FIG>. The alignment protrusions <NUM> and alignment recesses <NUM> may align the middle foam <NUM> on the support structure <NUM> such that the apertures <NUM> of the middle foam <NUM> are aligned with the aperture <NUM> of the support structure <NUM>. Additionally, the alignment protrusions <NUM> and alignment recesses <NUM> may restrict lateral movement of the middle foam <NUM> with respect to the support structure <NUM>. <FIG> illustrates an example embodiment in which the middle foam and PCB <NUM> have been mounted on the assembly fixture <NUM> and the middle foam serves as the support structure of the transducer assembly <NUM>. <FIG> depicts an embodiment including the crystal chassis, e.g. support structure <NUM>. The support structure <NUM> and middle foam <NUM> are mounted to the assembly fixture <NUM>. <FIG> depicts the example embodiment of <FIG> where the PCB <NUM> is also mounted to the assembly fixture <NUM>.

At operation <NUM>, an expansion foam slot, e.g. aperture <NUM>, may be cut into the top foam <NUM>. As depicted in <FIG>, the aperture <NUM> may be elongated in the longitudinal direction of extension of the top foam <NUM>, such that, when assembled, the transducer elements <NUM> are not covered by the top foam <NUM>, due to being exposed via the aperture <NUM>. The cut may be executed by a dye, laser, knife, or other suitable cutting tool.

At operation <NUM>, the top foam <NUM> may be mounted to the assembly fixture <NUM>. As depicted in <FIG>, the top foam <NUM> may be mounted to and/or aligned with the transducer assembly <NUM> by fitting guide holes <NUM> onto the guide posts <NUM>.

At operation <NUM>, flex tails <NUM>, e.g. the off board connection portion of the PCB <NUM>, may be inserted and aligned into a chassis front <NUM>, as depicted in <FIG>. The chassis front may be metal, ridged plastic, or the like, and be configured to restrain the middle foam <NUM>, and top foam <NUM> with the support structure <NUM>, e.g. the crystal chassis. At operation <NUM>, the chassis front <NUM> may be mounted to the assembly fixture <NUM> via guide posts <NUM>.

At operation <NUM>, piezoelectric crystals (e.g., transducer elements <NUM>) may be inserted into the flex circuit, e.g. PCB <NUM>, by press fitting the transducer element <NUM> between the flex tabs <NUM> of the PCB <NUM>, as depicted in <FIG>.

<FIG> illustrates a plurality of transducer elements <NUM> on an adhesive strip. In some example embodiments, the transducer elements <NUM> may be removed from the adhesive strip, such as by tweezers and inserted into the corresponding apertures <NUM> of the transducer assembly <NUM> between the flex tabs <NUM>, such as be a push probe, as depicted in <FIG>.

Alternatively, two or more, such as all transducer elements <NUM> of the transducer assembly <NUM> may be installed simultaneously. In one such example, a machine with a multi-head arm may be fed a plurality of transducer elements <NUM>, such as on the adhesive strip. The machine may align the plurality of transducer elements <NUM> with the apertures in the transducer assembly <NUM>. The multi-head arm may be driven toward the transducer assembly <NUM>, thereby pushing the plurality of transducer elements <NUM> into the corresponding apertures <NUM> between the flex tabs <NUM> of the PCB <NUM>. <FIG> illustrate the transducer assembly <NUM> with the transducer elements <NUM> installed.

At operation <NUM>, expansion foam <NUM> may be provided into the expansion slot, e.g. aperture <NUM>, such that the expansion foam <NUM> surrounds the transducer elements <NUM> and fills the cuts, e.g. apertures, in the base foam <NUM>, middle foam <NUM>, and at least a portion of the top foam <NUM>. As depicted in <FIG>, guard material <NUM> (such as paper, wax paper, polyurethane sheeting, or the like) may be installed around the aperture <NUM> in the top foam <NUM>. The expansion foam <NUM> may be poured into, e.g. across, the aperture <NUM> in the top foam <NUM>, as depicted in <FIG>. Excess expansion foam <NUM> may be caught by the guard material <NUM>, which may be removed subsequent to completion of pouring the expansion foam <NUM>. In some embodiments, the expansion foam <NUM> may be poured with the transducer assembly <NUM> inserted into the transducer assembly housing <NUM>, or one half of the transducer assembly housing <NUM> including a recess for the transducer assembly <NUM>, such that the expansion foam <NUM> fills gaps present between the components of the transducer assembly <NUM> and the transducer assembly housing <NUM>. Alternatively, a mold may be installed around a peripheral edge of the transducer assembly, which may become a portion of the transducer assembly <NUM>, or may be removed after expansion of the expansion foam <NUM>.

At operation <NUM>, the expansion foam <NUM> may be allowed to expand. Full expansion of the expansion foam <NUM> may fill gaps between components of the transducer assembly <NUM> and/or lock the respective positions of the components of the transducer assembly <NUM> relative to each other. <FIG> depicts a "loaf" of fully expanded expansion foam <NUM>.

At operation <NUM>, the fixture assembly <NUM> may be removed from the transducer assembly <NUM>. <FIG> illustrates a transducer assembly <NUM> with the assembly fixture <NUM> removed and the release sheet <NUM> visible.

At operation <NUM>, the release film <NUM> may be removed from the transducer assembly <NUM>, as depicted in <FIG>. The release film <NUM> may be peeled or otherwise removed to expose the emitting face of the transducer elements <NUM>.

At operation <NUM>, the transducer assembly <NUM> may be installed into the transducer assembly housing <NUM>, if not performed previously, such as in conjunction with operation <NUM>.

At operation <NUM>, a flex tail positioner <NUM> may be installed with respect to the transducer assembly housing <NUM>. As depicted in <FIG>, the flex tail positioner <NUM> may be installed between the flex tail <NUM> of the PCB <NUM> and the transducer assembly housing <NUM>. The flex tail positioner <NUM> may cause the flex tail <NUM> to be directed in a direction substantially perpendicular to, e.g. outward and away from, the chassis front <NUM> and/or transducer assembly housing <NUM>. Other electronic wires or cable may also be routed and secured to the transducer assembly housing <NUM>, as appropriate.

At operation <NUM>, the transducer assembly housing <NUM>, including the transducer assembly <NUM>, may be placed at a predetermined tilt angle. As depicted in <FIG>, the transducer assembly housing <NUM> may be set on a tilt plate <NUM> set at the predetermined tilt angle, such as <NUM> degrees, <NUM> degrees, <NUM> degrees, or the like.

At operation <NUM>, a urethane potting material may be provided over the transducer assembly <NUM>. <FIG> and <FIG> illustrate urethane <NUM> being poured into a portion of the transducer assembly housing <NUM>, such that the transducer assembly <NUM> is completely enveloped by the potting material <NUM>. In some embodiments, a release film may be applied to the emitting face of the transducer assembly <NUM> prior pouring the urethane <NUM>.

At operation <NUM>, the urethane <NUM> may be allowed to cure. <FIG> depicts the emitting face of the transducer assembly <NUM> in the transducer assembly housing <NUM> after the potting material <NUM> has cured and the release film has been removed. After completion of the assembly of the transducer assembly <NUM>, in some embodiments, the transducer assembly housing <NUM> may be closed, such as by installation of a second half of the transducer assembly housing <NUM>.

Claim 1:
A sonar transducer assembly (<NUM>) comprising:
at least one transducer element (<NUM>);
a flexible printed circuit board PCB (<NUM>,<NUM>) comprising at least one pair of opposing flexible electrical connection tabs for the at least one transducer element (<NUM>); and
a support structure (<NUM>) comprising at least one aperture (<NUM>) for the at least one transducer element (<NUM>), wherein the support structure (<NUM>) is configured to:
support the PCB (<NUM>,<NUM>);
allow flexion of the pair of opposing flexible electrical connection tabs (<NUM>) into the aperture (<NUM>); and
retain the at least one transducer element (<NUM>) in the at least one aperture (<NUM>),
wherein the transducer element (<NUM>) is installed between the pair of opposing flexible electrical connection tabs (<NUM>) on the PCB (<NUM>,<NUM>) and into the aperture (<NUM>) causing the flexible electrical connection tabs (<NUM>) to flex, wherein the flexion of the flexible electrical connection tabs (<NUM>) causes an elastic force to be applied against opposing ends of the at least one transducer element (<NUM>).