Method of fabricating a lightweight audio system housing assembly

A lightweight radio/CD player for vehicular application is virtually “fastenerless” and includes a fold-up case formed of polymer based material that is molded to provide details to accept audio devices such as playback mechanisms (if desired) and radio receivers, as well as the circuit boards required for electrical control and display. The case is of composite structure, including an insert molded electrically conductive wire mesh screen that has been pre-formed to contour with the molding operation. The wire mesh provides EMC, RFI, BCI and ESD shielding and grounding of the circuit boards via exposed wire mesh pads and adjacent ground clips. Side wall closure members are extruded of aluminum defining self-engaging attachment features for affixing to the case, providing electrical self-grounding with the wire screen and thermal grounding with internal power devices. The major components and subassemblies are self-fixturing during the final assembly process, eliminating the need for dedicated tools, fixtures and assembly equipment. The major components and subassemblies self-interconnect by integral guide and connection features effecting “slide lock” and “snap lock” self-interconnection.

TECHNICAL FIELD

The present invention relates generally to apparatus for enclosing electrical subassemblies, and more specifically relates to apparatus for efficiently securing subassemblies to a chassis of an electrical assembly such as an automobile radio, compact disc playing mechanism, cassette tape playing mechanism, navigational aid, personal computer, personal and telematic communication devices or disk drive mechanism.

BACKGROUND OF THE INVENTION

Devices such as automobile radios or personal computers contain subassemblies such as cassette playing mechanisms or disk drives that are attached to the chassis using threaded fasteners. The chassis provides structural support for the subassemblies and also provides electromagnetic shielding to limit electromagnetic interference (EMI) experienced by, and/or created by the device. The fasteners ensure that each subassembly within the chassis is properly located and securely retained within the chassis.

The use of such fasteners can have numerous drawbacks, particularly in a high volume production setting. The process for applying or installing fasteners can vary, but there is usually some degree of automation required, ranging from manually loading a screw into a bit on a pneumatic driver to using self-feeding automated machines. Typically, the torque applied by the device used to drive the fasteners must be monitored regularly and adjusted in order to assure proper seating of the fasteners. When fasteners are used, sheet metal tolerances, as well as tolerances of the fasteners themselves, have to be maintained at tight levels to allow for the minimization of stress in the assembly when aligning multiple fasteners with corresponding holes in the chassis and in the subassembly.

When threaded fasteners are used to assemble an electrical device, the assembly cycle time can be very long especially in high volume production. An operator assembling the device must typically first obtain the threaded fastener, orient and position it in alignment with the driver bit, then manipulate or actuate the machine to drive the threaded fastener. Furthermore, using threaded fasteners presents a risk of any one of the following upstream failures occurring: stripping of fastener threads; insufficient torque resulting in an unseated fastener; excessive torque resulting in distension/deformation of the fastener or adjacent electrical components; installation of the wrong fastener type or size; foreign object damage due to fasteners and/or metal shavings dropping onto the assembly and/or subassembly; and stripping of the head of the threaded fastener. Also, a fastener installation tool such as a driver and bit can slip off the fastener and impact an electrical component resulting in a damaged assembly.

If self-tapping fasteners are used, the process of driving the self-tapping fasteners into sheet metal often causes shavings of sheet metal to disperse into the assembly. Such shavings have been known to cause electrical failures, such as shorts or corruption of magnetic components that can permanently damage the product. If self-tapping fasteners are not used, an extra production step is required to pre-form threads in the sheet metal of the chassis and/or the subassembly to be installed within the chassis.

Fasteners further require an additional inventory burden on the production line in that the production line must be continuously stocked with part numbers (fasteners) other than the integral components that add value to the assembly. Also special tools specifically required for assembly, using fasteners, such as drivers and bits, must be continuously monitored and maintained for proper performance, wear and torque specifications. Typically, the top and/or bottom surface of the chassis must be secured in place after the subassembly is attached to the chassis.

Special fixtures are often required on the production line to secure a subassembly in a proper location and orientation while it is mounted within the chassis with fasteners. Such fixtures can be very complex, and the use of such fixtures usually requires extra handling of both the subassembly and of the resulting assembly thereby adding to the production cycle time and potentially compromising quality of the final product.

FIG. 1illustrates the construction of a typical prior art automotive radio/compact disc (CD) player10. Radio/CD player10comprises a radio subassembly whose principle circuit components are carried on a circuit board12and a CD player subassembly14. The circuit board12and the CD player14are encased within a common chassis16made up of sheet metal components. Chassis16includes a wraparound housing18defining a back and sidewalls, a top cover20, a bottom cover22and a front plate24which are interconnected by numerous threaded fasteners to collectively enclose the subassemblies. The top and bottom covers20and22, respectively, are provided with large arrays holes or openings for airflow and ventilation of heat generated within the radio/CD player10. A convector or heat sink26is carried on an outer surface of one of the chassis sidewalls and is interconnected through a port/window28to a power device assembly30. A trim plate assembly32, along with a support pad34and CD dust cover36are affixed to the front plate24, providing an operator control interface with the radio/CD player10. Circuit board12is electrically in-circuit with the CD player subassembly14through an intermediate flex wire cable38and with the power device assembly30through a jumper cable40. Information bearing labels42and44are provided for future reference by the operator and service technicians. The radio/CD player10is electrically interconnected with an antenna, power supply, speakers and other related systems of a host vehicle by rear-facing connectors46carried on the circuit board12which are registered with openings48in the rear wall of wraparound housing18. The radio/CD player10is mounted within a host vehicle by threaded fasteners passing through openings in mounting features50extending from front plate24and a rearwardly directed mounting bushing52which is threadably affixed to a stud54carried on the outer surface of the rear wall56of wraparound housing18. As best seen inFIGS. 11 and 12, the shank of the stud54extends outwardly through a hole58disposed concentrically with a localized recess60and the stud54is seated within the recess60.FIG. 90illustrates another known stud design including a threaded shank secured to the rear wall53of a radio set51by a set nut55and receiving a molded rubber, plastic or vinyl stud57thereover. Note the large number of threaded fasteners59.

The radio/CD player10ofFIG. 1is of ordinary complexity and may require fifty or more threaded fasteners to complete the manufacturing process. Installation of that many fasteners may require that the in-process chassis be re-positioned/re-fixtured ten to fifteen times as it passes along an assembly line of eight to ten skilled workers/work stations.

Vehicle entertainment systems usually include an audio component such as a radio to enable receiving signals from antennas, contain various forms of playback mechanisms, and have the capacity to accept data from user devices like MP3 players. Typically, the radio has a decorative assembly that provides man-machine interface as well as displaying pertinent data relative to the selected media and audio settings. Also, the back-end or chassis is constructed of metal to provide various functions to ensure the performance of the radio in the vehicular environment. The structure to contain the mass from playbacks, the heat conductive properties, and the electrical shielding and grounding are just a few of the advantages to using the metal construction. Unfortunately, with the density of the metal, the disadvantage of added weight is a side effect of the typical construction. In a vehicle, added weight impacts fuel economy, as well as other hidden costs during assembly that can effect the cost of the product, like sharp edges of metal can be a potential hazard for assemblers in the manufacturing plant as well as added weight can limit the packaging of multiple parts in containers for inter and outer plant distribution.

Thermal Management System

Devices such as automobile stereos, audio amplifiers, home stereo systems, two-way radios, computers, signal conditioners/amplifiers, compact disc playing mechanisms, and cassette tape playing mechanisms are examples of products that typically require electrical components to amplify signals and regulate power. Accordingly, such devices typically contain numerous electrical components such as single in-line package (SIP) amplifiers and regulators that are typically soldered into printed circuit boards. Such electrical components generate heat in use. The heat must be dissipated away from the electrical components to avoid damage that can be caused by excessive temperatures in the electrical components. For example, excessive temperatures can cause delicate electrical leads to fail or insulating materials to melt, thereby causing a short circuit resulting in damage to, or even failure of, the entire electrical device.

A convector is often mounted to an outer surface of such a device to dissipate heat generated by components by transferring the heat away from the components and the device to the convector and then to the air through radiation. In order to accomplish this, it is preferable that the convector be physically in contact with the component. The components and the convector can be pressed together to allow even better heat conduction from the components to the convector. Sometimes an intermediary material such as a thermal pad or silicon grease is used between the component and the convector to assist in creating an adequate heat transfer junction.

Many convectors are made from aluminum due to the high heat conductivity of that material. Convectors often include a plurality of fins to increase the effective surface area of the convector and thereby increase the rate at which the convector can dissipate heat. Typically, aluminum, convectors are formed by an extruding process, during which the fins can also be formed integrally therewith.

Convectors are usually assembled to the component or components during final assembly of the overall device in which they are used. At final assembly, components such as SIP amplifiers are already soldered into a printed circuit board. The order of assembly can vary as to which component is assembled into the chassis first. The printed circuit board can be installed into the chassis before the convector is mounted to the printed circuit board and the chassis. Alternatively, the convector can be mounted to the chassis before the printed circuit board is mounted to the convector. Sometimes, the convector is assembled to the printed circuit board to form a subassembly before being assembled to the chassis.

Typically, components are attached to the convector using a clip and one or more threaded fasteners that extend through a hole in the clip and into a hole in the convector. The clip, component and convector must all be simultaneously held in a fixture and then be fastened together with a threaded fastener. If the component includes a hole to accept a threaded fastener, it can be mounted directly to the convector using a threaded fastener that extends through that hole, without using a clip.

The use of such fasteners can have numerous drawbacks, particularly in a high volume production setting. Often, each hole in the convector that receives a fastener must be separately drilled or punched. This is especially true for an extruded convector if the axis of the hole is not aligned with the direction in which the convector is extruded. The fastening process can vary, but there is usually some degree of automation required, ranging from manually loading a screw into a bit on a pneumatically or electrically powered driver to using self-feeding screw machines. Typically, the torque applied by the device must be monitored regularly and adjusted in order to assure proper seating of the fasteners.

The clamping force between the convector and the component should be at a proper level to ensure sufficient heat transfer to the convector. When fasteners are used to attach the convector to the component, clamping force is a function of the type of fastener and its condition and degree of assembly (e.g. the level of torque applied during installation of the fastener). Thus, a threaded fastener that is not seated all the way will give less clamping force than one that is seated all the way. Or, a stripped or improper type of fastener may provide an insufficient clamping force.

Special fixturing is often required to hold a component in the proper location while it is mounted to the convector using one or more fasteners. Such fixturing can be very complex and use of such fixturing usually requires extra handling of both the component and of the resulting assembly, thereby adding to the production cycle time and potentially compromising quality of the final product.

When threaded fasteners are used, the assembly cycle time can be very long, especially in high volume production. The operator must specifically obtain the threaded fastener, bring it in contact with the driver bit, then drive the threaded fastened. If self-tapping fasteners are used, the process of driving the self-tapping fasteners into metal often causes metal shavings to disperse into the assembly. Such shavings have been known to cause electrical failures that can permanently damage the product. If self-tapping fasteners are not used, an extra production step is necessary to form threads in the metal of the convector.

Accordingly, there is a need for electrical assemblies that do not require fasteners or tooling for securing a component to a convector.

Vehicular radio chassis assemblies may typically contain a circuit board assembly and a playback mechanism that may have ground points from the circuit board to the enclosure. They also tend to have heat sinks added for conducting unwanted heat away from the radio circuit board power components to transfer the heat outside of the chassis. When the enclosure has been constructed of a non-metallic material such as plastic, the grounding and shielding has been provided by a variety of methods, including, but not limited to using a metal wire mesh that is insert molded with the structure of the plastic enclosure. Another method may include using localized shields that are assembled and soldered to the circuit board. However, this approach only provides a shield, not a ground. While plastic enclosures are desirable for manufacturing assembly simplification through the elimination of fasteners as well as weight reductions from the metal enclosures, the capitalization to provide a wire mesh insert to a plastic part has been a drawback, especially in low volume applications. Also, the manufacturing process flow has typically coupled the wire mesh insert fabrication cell directly with the plastic molding press, which may not be desired is the molding process utilization is not at a high enough percentage of the available molding press time.

Electrostatic Discharge Device

Static electricity (electrostatics) is created when two objects having unbalanced charges touch one another, causing the unbalanced charge to transfer between the two objects. This phenomenon commonly occurs in homes, vehicles and other environments when the air is dry (i.e. has a characteristic relatively low level of humidity). For instance, when a person slides onto a car seat, electrons may transfer between the two, causing the surface of the person's body to store a charge. When the person, then, touches a vehicle component, the charge may travel (discharge) from the body to the component, thus creating static electricity. If the object touched is an electronic device, such as a home stereo, home theatre system, computer, vehicle entertainment system or other electronic media system, this electrostatic discharge can be harmful to the sensitive electronic components of the device. For instance, when a person slides onto a vehicle seat and inserts a disc into the car stereo, a charge may travel from the body through the disc to the sensitive electronic components in the vehicle stereo. Similar problems may occur when using DVD and other magnetic media and disc players.

Accordingly, problems with the drainage of a static electric charge impacting sensitive electronic components continue to persist.

SUMMARY OF THE INVENTION

The present invention provides numerous product and process advantages which collectively result in substantial cost and labor savings. By way of example, the preferred design optimizes the assembly process. It minimizes the required handling of major components and subassemblies during the assembly cycle. Final assembly is optimized, wherein only seven major components and subassemblies are involved. This minimizes the number of work stations and fixtures, in-process transfers between work stations and total assembly cycle time. The inventive design permits selection of the optimal mechanical product configuration for a given receiver family. Furthermore, it permits idealized electrical and mechanical building block partitioning for common and unique elements.

The preferred embodiment of the invention contemplates screwless final assembly without the use of tools, fixtures and assembly machines. This greatly enhances in-process product flow in the factory, improves scheduling of final assembly, and allows labor intensive processes such as stick lead assembly to be largely moved off-line. This greatly reduces both direct and indirect labor requirements. Furthermore, inventory control is simplified inasmuch as position part proliferation is deferred to or near the end of process.

These and other features and advantages of this invention will become apparent upon reading the following specification, which, along with the drawings, describes preferred and alternative embodiments of the invention in detail.

Although the drawings represent varied embodiments and features of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to illustrate and explain the present invention. The exemplification set forth herein illustrates several aspects of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

The present invention can be applied in its broadest sense to electronic devices and systems where shielding from radio frequency interference (RFI), electromagnetic interference (EMI), bulk current injection (BCI) and/or electrostatic discharge (ESD) is required. In addition to vehicle based radios and audio entertainment systems, the invention can be advantageously applied in “infotainment” and telematic systems. Furthermore, the present invention employs virtually “fastenerless” design architecture to facilitate low-cost, high volume production techniques.

A telematics product is a two-way communication/receiver system that enables access by a vehicle occupant to vehicle related information like geographic position/location through the use of a GPS module with antenna, vehicle diagnostics, crash sensors and air bag deployment. It also contains a phone module that is linked through a microphone in the vehicle and the radio speaker system for hands free calling via voice recognition and links to a call center for a variety of services, including but not limited to emergency help, concierge, vehicle theft recovery, turn-by-turn route guidance, vehicle diagnostics and vehicle unlock.

For convenience of understanding, the following description will be focused primarily upon an automotive radio/CD player system.

Lightweight Radio/Cd Player for Vehicular Application

The present invention reflects an improved design to reduce the overall weight of an automotive radio/CD player without compromising the strength of the unit. The present invention employs a polymer based material that can be molded to provide the necessary features for the chassis as well as the frontal interface to the decorative front-end assembly described for the man-machine interface. By molding a case with the necessary details to accept the playback mechanisms (if desired) as well as the circuit board(s) needed for the electrical control, the required functionality of the unit is maintained as compared to the typical metal box. The necessary shielding and grounding is accomplished by insert-molding a mesh screen wire that has been pre-formed to contour with the molding operation. The grounding of the circuit boards may be accomplished by using ground clips attached directly to the ground pads of the circuit board that would interface directly with exposed screen wire mesh of the molded part. While metal is also a good conductor for the thermal load inside the unit, openings must be incorporated to allow airflow for additional cooling. The same openings can compromise the shielding. With in-molded mesh screen wire, the mesh acts as a Faraday cage to shield the electronics, but the open weave allows airflow to promote the dissipation of the thermal load from inside the unit, to the exterior. Besides the reduction of mass offered by the molded polymer material for the unit chassis and front plate, the hidden benefits include ease of handling in the assembly process as well as less container and shipping weight.

To facilitate assembly, the molded polymer chassis and front plate can use integral or molded in guideways and snaps, thereby eliminating the typical screw fastener assembly method previously used for these components. To enhance the rigidity, the component parts that comprise the assembly are sandwiched at the common vehicle instrument panel attachment points such that when the mounting screws are driven, they firmly clamp the component pieces to the host vehicle. In the event a playback mechanism of substantial mass and volume is required, the sub-assembly structure for the mechanism would utilize formed attachment tabs that would be an intermediate layer in the aforementioned component part sandwich. Another benefit for the mounting at the back of the radio is often vehicles have a receptive hole or slot in the inner cavity of the instrument panel carrier that accepts a mounting bushing or “bullet” shaped extension that is screwed to a mounting stud that is typically swaged to the back of the metal enclosure of the radio. The mounting “bullet” can be molded directly in the polymer-based case eliminating the additional part and the assembly of that additional part.

To replace the metal structure of the vehicle radio, a galvanized (or appropriately coated) steel mesh wire screen will be cut, formed, and molded with a polymer resin to provide necessary details for assembly of components required for the functionality of the radio including, but not limited to, a circuit board assembly, a heat sink for audio power and switching components, a playback mechanism, and a man-machine interface or trim plate assembly, as well as vehicle mounting features. While the polymer or plastic provides the majority of the mechanical structure for the radio, the in-molded mesh screen wire provides the needed protection from various electrical anomalies including electromagnetic contamination, radio frequency interference, bulk current injection, and electrostatic discharge, to name a few. The screen mesh also allows openings necessary for air passage or venting of heat from the radio by molding the radio back end or case and front plate. The many details and features needed in a typical assembly can be incorporated directly into the parts, eliminating the need for fasteners and separate additional parts often required with parts fabricated in metal.

The specific materials selected for fabricating the radio case and front plate will vary depending upon the application, including the contained mass of the mechanisms employed as well as the severity of the contemplated environment (esp. temperature and vibration). Examples of materials that could be employed for typical automotive applications are:

Major components which contact one another or are mechanically interconnected preferably are formed from material having substantially differing surface finish and hardness characteristics to minimize the possibility of resulting squeaks, rattles and the like.

Although presently viewed as cost prohibitive for automotive applications, it is contemplated that nano carbon tube filler can be employed within the plastic material forming the case and front plate to provide effective shielding and enhance the structural strength of the case assembly.

In addition to weight savings, which may amount to well over one pound (0.4536 Kg), the part handling is improved to reduce the amount of fasteners as well as separate component parts. Often a radio may be constructed from a wrap-around, a cover and the fasteners along with a mounting bushing or “bullet” screwed to a “swaged” threaded stud in the metal case. Also, the metal pieces require assembly personnel to wear gloves during handling to avoid any cuts or damage to their hands as well as protection from any metal fabrication fluid residue. Molded plastic does not require any special gloves, or the concerns of cuts to the skin. Aside to the benefit to the vehicle by reducing the radio weight by over one pound (0.4536 Kg), the savings for a manufacturer include reduced shipping cost through the weight reduction and potential container efficiency improvements. Product labeling can be improved through laser engraving the plastic with the desired number, customer logos, etc. Metal typically requires a stamping detail (not easily changed) and/or a printed label that is adhesively applied. This offers greater flexibility and eliminates additional parts (like labels) to use the plastic, as well as better durability than a label.

Referring toFIGS. 2-10, a consolidated radio/CD player apparatus62embodying many aspects of the present invention is illustrated. The radio/CD player62is an assemblage of six major components or subassemblies, a circuit board subassembly64, a CD player subassembly66, a box-like housing case68, a front closure member or front plate70, a convector or heat sink72and a trim plate subassembly74.

It is envisioned that each of the major components/subassemblies would be produced “off-line” and the final assembly process would comprise the efficient, high volume joining of the major components/subassemblies and end-of-line testing of the completed units.

FIGS.2and8-10depict plan and perspective views of the fully assembled radio/CD player apparatus62.FIG. 3is an exploded view illustrating the juxtaposition of the respective major components during the assembly process.FIGS. 4-7depict specific assembly steps of the major components as will be described hereinbelow.

The case68and front plate70are each preferably injection molded of polymer based material and collectively comprise a substantially closed housing assembly76. The case68has a box-like structure, including upper and lower wall portions78and80, respectively, left and right side wall portions82and84, respectively, and a rear wall portion86. The case68also has mounting features extending externally of the case walls, including left and right front mounting flanges88and90, respectively, extending from the forward edges of the left and right side walls82and84, respectively, and a mounting stud92extending rearwardly from the rear wall86. All of the case wall portions and mounting features of the case68are integrally formed in a single injection molding process. The case defines a front opening94which, upon assembly, is closed by front plate70. An assembly axis96extends symmetrically from front to rear of the case68, exiting opening94along the nominal centerline of the case96.

The circuit board subassembly64consists of a common or main printed circuit board (PCB)98and a unique, application specific PCB100which are electrically and mechanically interconnected by several pin connectors102. It is envisioned that edge connectors, ribbon connectors or the like could be substituted for the pin connectors102. The common PCB98contains all surface mount components. The circuit board subassembly64comprises an audio component.

The CD player subassembly66consists of a conventional multi-disc player unit104and substantially minor-image left and right side mounting brackets106and108, respectively, affixed thereto by integral fastener devices such as “squirts” (referFIGS. 40-42). Note that there are slight differences between the left and right mounting brackets106and108, but they are deemed to be inconsequential for purposes of the present invention. The left and right mounting brackets106and108have outwardly directed mounting flanges110and112, respectively, which, upon assembly, register with case mounting flanges88and90, respectively. The CD player subassembly66comprises an audio component.

The heat sink72comprises a substantially flat, stamped aluminum plate adapted for mounting to the outer surface of the left case sidewall82and includes a recessed portion114which, upon installation, extends inwardly through a port116in left case sidewall82for thermal interconnection to heat generating and power circuit components118,120and122carried on the main PCB98.

The trim plate subassembly74is configured to organize audio system input/output and display devices, informational indicia and decorative display devices for an associated host vehicle operator.

Referring particularly toFIGS. 4-7, a method of assembly of the lightweight audio system62of the present invention is illustrated. Audio system62can be assembled manually by an ordered process wherein a single (preferably, but not limited to) operator, who sequentially assembles the six major components or subassemblies on a designated work surface124. No specialized tools or separate/dedicated fixtures are required. No threaded fasteners/screws are required. Each or the major components and subassemblies form integral features which cooperate to interact with features of the other components and subassemblies to register, align and guide the components and subassemblies during adjoining thereof as well as to removably affix the components and subassemblies to one another when in their final design position. This process is referred to herein as the Slide-lock Snap-lock™ Screwless Assembly Technology and Method or “SLAT”. In effect, the components “self-fixture one another in combination the manipulation of the

Assembly of the radio/CD player62is affected by the assembly technician or operator taking the following steps:

As illustrated inFIG. 4, place the front plate70on the work surface124in an inverted position with the outer surface of the front plate disposed upon the work surface124. The centerline of the front plate70defines an assembly axis, as designated by arrow96extending normally to the work surface124.

The front plate has two laterally spaced, rearwardly directed extensions126and128integrally formed therewith. Extensions126and128form guideways or opposed slots130and132, respectively, which open towards one another and are directed parallel to the assembly axis96. Lateral edge guide surfaces134and136of the application specific PCB100register within slots130and132and are guided thereby during the insertion process until the leading edge surface138of the PCB100contacts the inside (upward facing inFIGS. 4 and 5) surface of front plate70. At this point, common PCB98is cantilever suspended from PCB100via pin connectors102and other supports (not illustrated). ReferringFIG. 5, the circuit board subassembly64is retained in position by the interfit of the edge surfaces134and136within slots130and132.

The CD player subassembly66is next installed by manipulating it along the assembly axis96until through holes140and142, formed in bracket mounting flanges110and112, register with locating pins or nibs144and146integrally formed in laterally extending mounting flanges148and150, respectively, integrally formed in front plate70. Thereafter, the CD player subassembly is displaced downwardly along the assembly axis96until the lower surfaces of bracket mounting flanges110and112abut the upper surfaces of front plate mounting flanges148and150. The CD player subassembly66is retained in the position illustrated inFIG. 5by an interference fit between the front plate nibs144and146, and the mounting bracket flange through holes140and142.

Mounting bracket flanges110and112have secondary, larger diameter through holes152and154formed therein which register with similarly dimensioned through holes156and158, respectively, formed in front plate mounting flanges148and150for receiving attachment means such as bolts, for affixing the completely assembled radio/CD player62to a host vehicle.

The steps of installing the circuit board subassembly64and the CD player subassembly can be reversed from that describer hereinabove.

The housing case68is next installed by manipulating it along the assembly axis96whereby the case wall portions78,80,82,84and86fully envelop the circuit board subassembly64and CD player subassembly66in combination with the front plate70.

As best viewed inFIGS. 3,5and27, the centerline of the case68is first manually aligned with the assembly axis96and rotationally positioned with the subassembly consisting of the circuit board subassembly64, CD player subassembly66and the front plate70, whereby a first cooperating pair of guideways160and162integrally formed in case sidewall portions82and84register with the CD player mounting brackets106and108and, simultaneously, a second cooperating pair of guideways164and166integrally formed in case sidewall portions82and84register with lateral edge guide surfaces168and170of common PCB98. The case68is then manually displaced along the assembly axis96until the leading edge thereof defining front opening94contacts the rear surface of the front plate70. Thereafter, cooperating ramped snap-engagement features172and174integrally formed with upper and lower wall portions78and80of the case68and the front plate70, respectively, momentarily self-displace one another and snap back to self-engage to establish a positive interlock therebetween.

The case mounting flanges88and90form through holes176and178which register and self-engage with nibs144and146, respectively, to provide a redundant engagement feature. Furthermore, the case mounting flanges88and90form a second set of through holes180and182, respectively, which register with through holes152and154of mounting brackets106and108, and through holes152and154of front plate mounting flanges148and150, respectively.

As best viewed inFIGS. 2,6and7, the heat sink72is next installed. The heat sink72includes several locating tabs182integrally formed along one edge thereof and a locator recess184formed in an opposed edge. The heat sink72is manually affixed to the outer surface of the case left side wall portion82which defines integral tab receiving extensions186along the upper edge thereof. Once the heat sink locating tabs182are inserted within their respective case wall portion extensions186, the heat sink72is rotated into its design position illustrated inFIG. 7wherein a resilient ramped catch member188integrally formed along the bottom edge of the left side wall portion82snap engages the recess184to fixedly interlock the heat sink72to the case68.

When the heat sink72is in its installed position, the recessed portion114extends inwardly into the case68through the port116. The inner surface of the recessed portion114establishing an abutting relationship against the power circuit components118,120and122to provide a cooling thermal convector to the exterior of the case68. Means are provided to ensure that components118,120and122remain in intimate contact with the heat sink72such as screws190, or, preferably to continuously resiliently urge the components into engagement with the recessed portion114of the heat sink72.

It is contemplated that the heat sink72could be alternatively mounted to the case rear wall portion86, whereby it would be installed along the assembly axis96.

Referring toFIG. 7, the final step of assembling the major components and subassemblies is illustrated. First, the subassembly of the components illustrated inFIG. 6is manually inverted, with the case rear wall portion86disposed on the designated work surface124. Due to the localized outward projection of the stud92, a stability enhancing spacer (not illustrated) or, alternatively, a recess192in the work surface124ensures a stable platform to complete assembly.

The trim plate subassembly74is then manipulated to become in register with the case68and manually displaced along the assembly axis96until the lower surface of the trim plate assembly74contacts the upper surface of the front plate70(as depicted inFIG. 7). Thereafter, cooperating ramped snap-action engagement features192and194integrally formed with upper and lower edge skirt surfaces of the case trim plate assembly74and the front plate70, respectively, momentarily self-displace one another and snap back to self-engage to establish a positive interlock therebetween.

The completed assembly of the major components and subassemblies is depicted inFIGS. 2,8-10and26. Following the assembly process, the completed radio/CD player62is placed in a queue for testing and quality checks.

As is best illustrated inFIG. 27, vertical and horizontal bosses208and210, respectively, are located directly interiorly of the stud92to reinforce the rear wall portion86of the case68to prevent “oil-canning” and allows use of relatively thin wall section for enhanced weight saving.

FIGS. 27-29illustrate an alternative construction of the case68and front plate70of the housing assembly76wherein both elements of the case assembly76are formed of a composite of relatively rigid polymer material and electrically conductive material operable to shield the audio components (such as the circuit board subassembly64and the CD player subassembly66) from electrical anomalies including radio frequency interference (RFI), electromagnetic interference (EMI), bulk current injection (BCI) and electrostatic discharge (ESD). The electrically conductive material comprises substantially continuous planer sheet portions applied to surfaces of or within polymer housing assembly wall portions as discrete elements, electrically conductive paint, foil or electrostatic or vacuum deposition applied material. Alternatively, the electrically conductive material comprises a wire mesh screen212which has been cut and folded to net shape and inserted within a mold cavity whereby it is effectively insert molded within the polymer based material. Preferably, the wire screen212is centered within the wall portions of the case and front plate whereby electrically insulating polymer material effectively covers the wire screen212, both inside and out, to prevent inadvertent grounding of the housing assembly to interior or exterior structures.

Through empirical testing and development, the inventors have found that it is preferable to locate the wire screen212near the inside surface of the case68and the outside surface of the front plate70. Openings214are provided in the case68by locally eliminating the polymer material but leaving the wire screen intact, whereby judiciously positioned openings214provide natural convection cooling to the ambient without having a break or gap in the electrical anomaly protection provided by the wire screen212.

Circuit Board Grounding to Wire Mesh System

The common circuit board and the unique circuit board are grounded to the molded in wire mesh by using a grounding clip that contacts the ground plane on the circuit board to the metal mesh by pressing the circuit board with the clip installed into a hole or recess in the plastic box that exposes the mesh. A point/ridge/protuberance is used on the clip to press into the mesh and increase the pressure for intimate contact. An alternative of this clip is one that gets surface mounted and soldered to the board and does not require manual assembly.

Referring toFIGS. 15 and 16, one form of grounding the ground plane216of the circuit board subassembly64to the wire screen212is illustrated. The leading edge surface138of the unique PCB100carries two beryllium copper grounding clips218, which are electrically and mechanically connected to the PCB ground plane216. Similarly, a trailing edge surface222of the common PCB98carries two grounding clips218. Each grounding clip218includes a resilient contact arm220extending outwardly along the assembly axis96. Upon assembly, the grounding clips218carried on the leading edge surface138of PCB100register with exposed wire screen212within windows224in front plate70(referFIGS. 94 and 95), and the grounding clips218carried on the trailing edge surface222of PCB98register with exposed wire screen212within windows226in the rear wall portion86of the case68. The contact are220of each grounding clip218is configured to continuously bear against the adjacent exposed wire screen212to maintain electrical contact therewith.

Referring toFIGS. 32-38, alternative forms of grounding the ground plane216of the circuit board subassembly64to the wire screen are illustrated.FIG. 133illustrates a radio/CD player622similar in all material respects to the radio/CD player62described hereinabove in connection withFIGS. 2-10and15-20inter alia, with the exceptions described immediately hereinbelow. In essence, in this embodiment, the four ground clips218contained on the circuit board subassembly64are deleted and replaced by connectors integrally formed with the housing assembly76.

Referring toFIGS. 32,34and36, a circuit board subassembly624includes a common PCB626interconnected with a unique PCB628by pin connectors630. A leading edge631of the unique PCB628, when installed within a front plate632, engages two Z-clips634integrally formed within the front plate632, whereby wire screen636exposed in the Z-clip634engages a contact pad/plane638carried on the unique PCB628adjacent its leading edge631. A trailing edge652of the common PCB626, when installed in a housing case654, engages two grounding clips658integrally formed within the case654, whereby wire screen636exposed in the grounding clip656engages a contact pad/plane658carried on the common PCB626adjacent its trailing edge652.

As best viewed inFIGS. 34 and 36, the Z-clip634includes a frame640integrally formed adjacent one side of an associated opening642and extending inwardly (within an associated housing case643) therefrom as a resilient cantilever. The frame640includes two parallel “L′ or “J” shaped leg portions644interconnected by a cross support portion646. A flap of wire screen636is die-cut prior to being injection molded within the front plate632. During the injection molding process, the edges of the wire screen flap are insert molded within the leg portions644, the cross-support portion646and the adjacent front panel of the front plate632, thereby exposing the wire screen flap636for electrical connection with the unique PCB contact pad638. An inwardly directed boss648is integrally formed on the front plate632adjacent an edge of the opening642opposite from the leg portions644, and extends substantially parallel to an assembly axis649. The boss648forms a guide/abutment surface650which is spaced from the exposed wire screen flap636by a dimension slightly less than the thickness of the unique PCB628to ensure a tight compressive fit when the leading edge631of the unique PCB628is inserted therebetween. The natural resiliency of the polymer material forming the Z-clip frame640ensures continued continuity of the electrical connection between the exposed wire screen636of the Z-clip and the unique PCB contact pad638.

As best viewed inFIGS. 33 and 35, the grounding clip656includes a cooperating pair of laterally spaced support members660and662integrally formed in a rear wall portion664of the case654adjacent the bottom edge of an associated opening663and extending inwardly therefrom. A flap of wire screen666is die-cut prior to being injection molded within the case654. During the injection molding process, the lateral edges of the wire screen flap666are insert molded within the support members660and662and the adjacent portion of the case rear wall portion664, thereby exposing the wire screen flap666for electrical connection to the common PCB626contact pad658. A wire screen positioning finger668is integrally formed in the rear wall portion664of the case654laterally intermediate the support members660and662, and extends inwardly from the rear wall portion664substantially parallel to an insertion axis670as a resilient cantilever. The positioning finger668is vertically positioned with respect to the support members660and662to continuously contact the lower surface of the wire screen flap666to ensure that the lateral center portion of the wire screen flap666is bowed slightly upwardly and resiliently maintained at least slightly above the upper surface portions672and674of the support members660and662, respectively. An inwardly directed boss676is integrally formed on the rear wall portion664of the case654adjacent the top edge of the opening663opposite from and laterally centered with the support members660and662. The boss676forms a guide/abutment surface678which is spaced from the exposed wire screen flap666by a dimension slightly less than the thickness of the common PCB636to ensure a tight compressive fit then the trailing edge652of the common PCB636is inserted therebetween. The natural resiliency of the polymer material forming the ground clip656structural elements ensures continued continuity of the electrical connection between the exposed wire screen666of the ground clip656and the common PCB contact pad658.

Referring toFIGS. 37 and 38, another example of self-grounding is illustrated wherein a PCB680includes an extension682projecting forwardly therefrom in line with an assembly axis684of a housing case686for an audio system687. Contact pads688and690are carried on upper and lower surfaces692and694of the PCB extension682. A rear wall portion696of the case686forms a window698exposing a portion of wire screen700which is aligned with the PCB extension682. When the wire screen700is insert molded within the polymeric material forming the case686, the portion thereof coinciding with the window698is left intact. During the assembly process of the audio system687, wherein the PCB is installed by insertion along guideways (not illustrated) within the case686, the PCB is inserted with sufficient force to locally rupture and penetrate the exposed wire screen700within the window688. Following the rupture of the wire screen700, the residual separation edges thereof are drawn into the window698by friction caused by motion of the upper and lower PCB surfaces692and694, respectively. When the PCB680assumes its installed position, as illustrated inFIG. 139, the rended portions of the wire screen700are compressively fit between the contact pads688and690and the adjacent edges of the window698, ensuring continued continuity of the electrical connection between the exposed wire screen700and the PCB contact pads688and690. It is contemplated that a single (one side of the PCB) contact pad can also be employed. However, the redundancy afforded by the dual contact pads688and690is preferable.

A modification of the self-grounding system described in connection withFIGS. 138 and 139can enhance assembly of an audio system702for simplified and improved unit-to-unit repeatability. A housing case704includes a wall portion706forming a window708exposing a wire screen710to establish a point of electrical connection to an audio component within the case704. After the wire screen710is insert molded within the polymer material forming the case704, but before the assembly if the audio system702, a tool, such as a cooperating punch712and die714is pressed simultaneously against the inner and outer surfaces of the exposed screen710within the window708to form perforations or weakenings, indicated by dotted lines716. This process step is indicated by arrows718. The perforations716make the exposed wire screen710more predictably frangible for improved unit-to-unit quality. Thereafter, during final assembly of the audio system702, the wire screen710separates along the perforations716when contacted by the leading edge of a PCB extension682(referFIGS. 37 and 38).

An alternative self grounding approach involves modifying a leading surface720of an extension722of a PCB724to form a sharpened, laterally extending leading edge726. The leading edge726can be formed by the PCB material itself or, preferably, by hardened material, such as a metal appliqué or band formed in a “U” or a “V” configuration engaging the PCB724by upper and lower members728and730affixed to the upper and lower surfaces732and734of the PCB extension722such as by soldering. The upper and lower members730and732can serve as electrical ground pads. Upon installation of the PCB724, the sharp leading edge726first contacts and cleaves the exposed wire screen710into the form illustrated inFIG. 139.

In addition to the forgoing, punch dies712/714such as those depicted inFIG. 156can be employed in modified form to actually sever and/or remove a portion (or all) of the wire screen710after the molding of the housing case704, but before the final assembly of the audio system702. Furthermore, one or more service access windows can be provided elsewhere in the walls of the housing case704. The service windows are closed at the time of manufacture by exposed screen including perforations, as depicted inFIG. 155. The exposed screen could be severed by a tool or process later in the service life of the audio system702to service or modify the system.

Front Plate Esd Grounding to Keyboard Through Wire Mesh

The method of grounding the plastic front plate (with molded in metal mesh) to the keyboard is by using plastic spring clip that contains an open window to expose the mesh where the spring clip comes into contact with a tinned pad on the keyboard. This provides an ESD path to ground when inserting a static charged CD into the CD changer.

Referring toFIGS. 13-17and28-30, several spring clip structures228are integrally formed in the front plate70which, in assembly, continuously resiliently bear locally exposed segments of the wire screen212against a tinned grounding pad230(only one is illustrated) on a keypad PCB232to establish a ground path therebetween.

Each spring clip structure228has a frame234including two parallel arc shaped portions236and238and a cross-support portion240integrally formed with front plate70and extending therefrom as a resilient cantilever. An opening242in the front plate registers with each spring clip228to permit flexure thereof.

Prior to molding of the wire screen212within the front plate70the screen preform is die-cut to form an integral flap which is captured within the mold and the edges thereof encased within arc-shaped portions236and238and cross-support portion240. The central portion of the exposed wire screen is expanded or stretched to form an outward bow shape (referFIGS. 18 and 20) to ensure that the resulting exposed screen protuberance firmly contacts the PCB grounding pad230.

Referring toFIG. 17, a prior approach is illustrated wherein separate spring grounding clips244are each mechanically affixed to the front plate246of a radio/CD player assembly248by a rivet250or other suitable fastener. The rivets are required to establish an electrical ground path as well as to mechanically secure the spring clips244to the front plate246, adding labor, cost and complexity to the manufacturing process.

Front Plate with Integral Assembly Fixturing

Using a plastic front plate enables assembly fixturing for the CD mechanism and circuit boards for slide lock and snap lock assembly instead of the screws used in a traditional receiver.

Referring toFIGS. 4 and 5, guideways in the form of slotted extensions126and128, as well as locator/retention features144and146integrally formed on the reverse (inside) surface of the front plate70provides a number of significant advantages in the manufacture and final assembly of the radio/CD player62by reducing product part count, assembly time, and substantially eliminates dedicated hard fixturing and tools to affect assembly.

Thermal Management System for Vehicular Radio Application

The thermal devices are placed in a window in the plastic box_and are attached to the heat sink, which is attached to the inside of the box. This puts a plastic wall (a good insulator) between the heat sink and the CD mechanism to minimize the temperature that a CD reaches inside the box metal case. The thermal efficiency of this system eliminates the need for a cooling/ventilation fan.

Referring toFIG. 159, another simplified alternative embodiment of a fastenerless thermal control system for an audio device342is illustrated. The audio device342comprises a case344formed of thermally insulating material. A PCB346is disposed within the case344which has a power circuit component348cantilever affixed thereto via its lead frame349positioned adjacent a thermal port350. A retainer/backing clip352is snap-engaged with a feature353on the exterior of the case344and includes a resilient integral support member354extending through the port350and continuously resiliently urging the power circuit component350toward the port350. A heat sink356snap-engages with features on the case344and backing clip352to retain it in its illustrated position wherein the power circuit component348is maintained in intimate contact with the inner surface of a recessed portion358of the heat sink356extending through the port350.

Convection air flow (arrows359) can be provided by providing inlet and outlet windows360and262in the case344. A pocket364formed on the outer surface of the heat sink356as part of the recessed portion358can be filled with a thermally conductive material366to increase the effective thermal mass of the heat sink356and to improve radiant thermal rejection as indicated by arrows368.

Low Cost Structural Support for Cd Changer For Vehicular Radio Application

Using a plastic box for the receiver enables low cost location and support for the CD mechanism and enables for slide lock assembly instead of the screws used in a traditional receiver. The brackets on the CD mechanism have a 1° taper that matches a 1° taper on the support shelf in the plastic box. This makes it easy for an operator to start the slide, but all of the clearances go to zero as the box snaps into place providing a strong rattle free assembly without the use of the traditional screws.

Wire Mesh for Structural Component

Molding in metal mesh into the plastic receiver case and front_plate increases the strength of the material (much like putting re-bar into_concrete) while still weighing less than a steel case. The gauge of the wire forming the mesh can be increased and the amount of plastic material can be substantially reduced, resulting in a very thin wall, robust structure.

As an alternative, the plastic can be eliminated from the center portions of some or all of the individual side, front, back, top and/or bottom panel portions of the case and front plate. This configuration would have the appearance of a screen box, with a molded plastic peripheral frame circumscribing each panel portion.

A lightweight automotive audio system471can include a housing case472constructed of a composite of polymer based material with a wire screen474insert molded therein to isolate audio components therein from various electrical anomalies. To further reduce overall weight, the gauge of the wire screen can be increased whereby the screen contributes a significant component of the resulting overall structural strength of the case, while the nominal section or thickness of the polymer material can be substantially reduced. By way of example, the case472top and bottom wall portions476and478, respectively, and left and right side wall portions480and482, respectively, injection molded into a single unified structure, with the enlarged gauge wire screen474insert molded adjacent the inner surfaces thereof. Edges and corners of the case472formed at the intersection of two or three adjacent wall portions can be locally thickened to increase structural rigidity of the case472as well as to provide internal and external mounting and interface ports. The intersecting edges of the top wall portion476and the left and right side wall portions480and482, respectively, form thickened left and right upper edge frames484and486, respectively. Likewise, the intersecting edges of the bottom wall portion478and the left and right side wall portions480and482, respectively, form thickened left and right lower edge frames. Lower edge frames488and490are locally vertically extended openings492and494for exposing the wire screen474to establish electrical contact with contact clips496and498carried by PCBs500and502, respectively, interconnected by pin connectors504within the case472.

Using plastic for a receiver case enables low cost assembly of the components. The circuit boards and the CD mechanism can slide into place and then be locked or they can be snapped into place without screws. This reduces the number of parts required in the assembly and reduces the amount of direct and indirect labor to put a receiver together. The plastic case can be easily molded into a net shape forming the slides and snaps needed for assembly.

Referring toFIGS. 2-10, the apparatus and assembly method described substantially reduces the labor and component cost of the radio/CD player62, as well as the required capital costs. Furthermore, it substantially enhances product quality by substantially eliminating the possibility of extraneous or missing (small) parts and/or improper assembly.

Using the molded in metal mesh in the receiver plastic box that is grounded to the circuit boards creates a Faraday cage that provides shielding protection for RFI (Radio Frequency Interference), EMI (Electro Magnetic Interference), BCI (Bulk Current Injection), and ESD (Electrostatic Discharge).

Refer toFIG. 12and their associated descriptions

Partitioned Main Board into Common and Unique

Using the principle of communization and modularity, the receiver main board has been divided into a common board and a unique board. This is counterintuitive because a single board is less expensive than two boards performing the same function. However, the common board contains all surface mount components (no stick lead or wave solder) and very large volumes can be produced without reconfiguring the assembly/production line. This will substantially reduce the manufacturing cost of this portion of the main board.

Referring toFIG. 11, automotive audio systems are unique in that they are typically designed in modular form and, in response to the requirements of individual customers, are produced by assembling individual units from varied combinations and permutations of modularized subcomponents. This, however, can be contrary to the manufacturing doctrine of large enterprises wherein large volume production of common designs is preferred for its inherent efficiencies. In the practice of the present invention, the individual electrical components to be assembled on the circuit board subassembly64are segregated into those which will be employed in each specie and sub-specie in a given product family. The commonly employed circuit elements (typically surface mount devices) are assembled on the “common” PCB98. The application specific circuit elements (typically “stick” mount devices) are assembled on the “unique” PCB100. The common PCB98is assembled employing highly automated manufacturing techniques for maximum efficiency, while the unique PCB100are assembled employing a different mix of labor and automation to maximize overall efficiency. Standard connector assemblies736,738and740are provided on the common PCB98for interfacing the radio/CD player62with speakers, ground, power and associated control/readout systems via wire harnesses. A standard coaxial cable connector742is also provided on the common PCB98for interfacing with a vehicle antenna system.

An audio product manual entitled “2004 Model Year Ford Freestar Radios” (Document Number 04-RDPD-12-MA-F), dated 7 Oct. 2005, describes in detail the circuit architecture of a family of modern automotive audio systems developed and produced by the assignee of this application. In addition, the manual enumerates the individual electrical components employed and their arrangement in various audio subsystems. In the practice of the present invention, the listed individual electrical components would be segregated into the common PCB98and unique PCB100in keeping with the teachings herein. Accordingly, the above referenced audio product manual is incorporated herein by reference for the sake of completeness and to serve as a resource in understanding and practicing the present invention.

Guillotine Heat Sink

The guillotine heat sink uses a flat aluminum plate as a heat sink. It slides down a slot on each side of the plastic box until it comes to rest on the quad bridge amplifier (QBA) IC and the power supply IC. Each IC will have a silpad on top to provide compliance and facilitate heat transfer. A downward force will be applied to the heat sink through a molded leaf spring in the lid of the plastic bob when it is snapped into place. An additional feature of the plastic box is to provide pillars under the FR-4 board in the location of the power ICs to provide a backstop for the leaf spring force.

Screwless Power Clip

The screwless power clip is an extension of a clip that Grundig uses in automotive radios produced in Europe today. The Grundig clip uses a long lever arm that must be snapped after the PCB is assembled into the metal wrap around. This requires an operator to reach in with a tool and snap (distend and release) the clip.

In the present invention, the long lever arm is eliminated. The present invention uses the assembly action of hooking the bottom of the heat sink into plastic stirrups and rotating the top of the heat sink until it snaps at the top of the plastic box to provide the lever action. This assembly technique can be accomplished by an operator without the use of expensive or specialized tools.

An additional approach to this idea is to eliminate the clip altogether and to employ a spring material as part of the lead frame.

In this mechanical configuration, the case starts out as a flat set of plastic sides with molded in metal mesh to act as the hinges for folding the case into a three-dimensional structure. This approach allows for bottom-up assembly that starts by snapping the board to molded features in the bottom plate. The heat sink is snapped to features in the back plate and the CD mechanism is attached to the front plate with two screws. The box is then folded up and snapped together.

The common edges of adjacent case panels define living hinges extending partially or entirely along the length thereof. The living hinge can consist of wire mesh only, where there is a gap in the plastic material, as illustrated inFIG. 22. Alternatively, the living hinge can comprise a thin web of plastic only, wherein the wire mesh has been interrupted. In another embodiment, the plastic-wire mesh composite can be molded to define a thin web as the living hinge, as illustrated inFIG. 17. In another embodiment, the plastic-wire mesh composite can be crushed or deformed to define the living hinge, as illustrated inFIG. 24. Finally, a portion of the plastic and/or wire mesh can be scribed or machined away to expose the wire mesh to define the living hinge. If the case material is thin enough at the hinge point, the hinge can be segmented, rather than continuous.

Referring toFIGS. 18-25, several variants of a housing assembly1086for an automotive audio system1088are illustrated. This version of the audio system1088is configured to be hand assembled and is nearly fastener-less. The fasteners which are employed are extremely elemental and require only the most rudimentary of hand tools to affect assembly. In essence, the audio system housing assembly1086comprises a case portion1090and a closure member or front plate1092. The case1090is presented to the assembler in an unfolded, two-dimensional arrangement whereby he/she can easily complete the final assembly process on a table top, eliminating complex and expensive tooling fixtures and multiple work stations.

The case portion1090is initially created as a sheet-like preform1094consisting of a number of flat panels interconnected along their adjacent edges. As best viewed inFIG. 18, the preform1094defines five distinct panels, which will constitute a bottom or lower wall portion1096, a right side wall portion1098, a left side wall portion1100, a top or upper wall portion1102and a rear wall portion1104. The adjacent panels are commonly joined or integrally interconnected by living hinges1106, enabling the panels to be repositioned normally to one another to form a three-dimensional box-like case1090.

The preform1094can be die cut from a continuous sheet of source material or, alternatively, injection molded in a net shape as illustrated inFIG. 18. In either case, the material employed to make the preform is a composite of at least one layer of relatively rigid polymer based material and at least one layer of electrically conductive material capable of shielding audio components, such as a radio receiver circuit1108or a CD player subassembly1110from electrical anomalies such as radio frequency interference (RFI), electromagnetic interference (EMI), bulk current injection (BCI), and electrostatic discharge (ESD). Cooperating engagement features such as tabs1112and catches1114are affixed to or integrally formed with the preform1094. ReferFIGS. 20 and 21. By way of example, after installation of the internal subcomponents, the case preform is folded to assume its ultimate box-like configuration. This places cooperating associated pairs of tabs1112and catches1114in an assembly orientation with the tab1112carried on the edge of one panel (the right side wall portion1098, for example) and the catch1114carried adjacent the edge of a now adjoining panel (the rear wall portion1104, for example). Final structural fixation of the preform1094in the form of the housing case1086is completed by simply snap-engaging the tab1112with the catch1114from the configuration ofFIG. 20to the configuration ofFIG. 21. After all of the tab1112/catch1114pairs are interconnected, the formation of the case1090is complete.

Prior to folding up the case1090, the radio receiver circuit1108is positioned and affixed to the exposed surface of the lower wall portion1096. A heat sink1116is similarly positioned and affixed to the exposed surface of the rear wall portion1104. The positioning and attachment of the internal components can be accomplished by features integrally formed in the formation of the preform1094(such as snaps, locating guides and the like), adhesives, discrete attachment and guide elements or inter-engagement with the various wall portions and other assembly elements within the case1090.

After formation of the case1090, the CD player subassembly1110can be pre-assembled with the closure member1092via screws1118or other interconnecting features described herein. A rear bracket1124secured to the back side of the CD player subassembly1110by screws1122includes a rearwardly extending threaded post1124which, upon final assembly extends through registering passageways1126in the heat sink1116and rear wall portion1104and engages a mounting bushing1128. This arrangement provides an extremely robust overall structure to the overall audio system.

The electrical components comprising the radio receiver circuit1108are arranged on a “common” component PCB1130and a “unique” PCB1132. The common and unique PCBs1130and1132are electrically interconnected by a ribbon connector1134. The heat generating electrical components1136are arranged on the common PCB1130and are affixed to the heat sink1116by screws1138or other suitable means, to enhance thermal coupling therebetween. Electrical connectors1140and1142are also arranged on the common PCB1132in register with port openings1144and1146in the rear wall portion1104of the case1090. A vertically opening electrical socket1148is centrally disposed in the unique PCB1132to receive a rigid connector1150extending downwardly from the CD player subassembly1110. This arrangement electrically interconnects the two audio components as well as provides structural support thereof.

One embodiment of the composite material employed for the housing assembly1086consists of a layer of elastomeric material1152with a continuous wire screen1154insert molder therein adjacent an interior wall surface1156of the composite structure. Referring toFIG. 19, the living hinges can be formed by an extremely locally thin (or non-existant) layer1158of polymeric material and the wire screen1156.

Referring toFIG. 22, air vents1160can be provided in the case1090by locally eliminating the polymeric material layer1152while maintaining the continuity of the wire screen1156to permit airflow, as indicated by arrows1162, therethrough.

Referring toFIG. 24, an alternative living hinge1164can be formed post-production of the composite material by pressing alternating undulations1166therein along the axis of the intended living hinge1164.

Referring toFIG. 23, a first process for producing composite material is illustrated, including drawing polymeric sheet material off upper and lower continuous rolls1168and1180to enclose an intermediate layer of wire screen from a third roll1172. The three discrete sheets are heated at station1174, rolled together at station1176, cured at station1178, cut-off or die cut to form performs at station1180, scribed, punched treated and/or formed at a station1182, and, finally, assembled at a workstation1184.

Referring toFIG. 23, a second, alternative process for producing composite material is illustrated drawing a continuous sheet of wire screen off a roll1186and drawing it through a continuous extruder/molder1188to form the composite structure. Thereafter, the composite sheet is shaped at station1190, cut off and/or punched at a station1192, and, finally, assembled at a work station1194.

Assembly of the audio system1088is completed by affixation of a trim plate subassembly (not illustrated) such as the device described in connection withFIGS. 2-10hereinabove.

Referring toFIG. 31, a known trim plate assembly1480is illustrated to highlight the substantial complexity, high part count, and design shortcomings resulting from providing back-illumination using traditional design and assembly techniques. The trim plate assembly1480includes a black plastic front panel1482(with operator controls and displays affixed on the opposed side), a printed circuit board (PCB)1484mounted on the exposed face of the front panel1482, three separate and discrete lightpipes1486mounted on the exposed face of the PCB1484by eight fastening screws1488and five light emitting diodes (LEDs)1490carried on the PCB1484.

Squirts

To further the innovative construction of the present invention, “squirts” or screwless retention features are employed. Restated, squirts are a drawn feature from a structural element, or a styled protrusion at the interface of two structural elements. Although applicable broadly, squirts are principally applied in the preferred embodiment of the invention to secure the CD player subassembly to the left and right CD player guide brackets. This allows the elimination of six additional screws.

A squirt is a retention feature which is integrally formed in a typically planer region of a structural member, such as a CD player guide bracket, which extends above one surface thereof and, during assembly, self-engages within an opening formed in an adjacent structural element, such as a hole in the outer case of the CD player subassembly. Squirts permit assembly of the guide brackets to the CD player assembly by hand without the need for special fixtures and power tools.

The squirts are formed from stock material during formation of the brackets themselves and do not add significant cost to the finalized bracket component. Similarly, mating holes can be easily punch formed in the adjacent case panels of the CD player subassembly.

In addition to reduced cost and ease of assembly, the squirt self-aligns the respective components during the attachment process, thereby ensuring their precise juxtaposition. Furthermore, the squirt is permissive of lower tolerances in the forming and assembly of its associated elements. In fact, the presence of slightly misshapen features or metal flash resulting from low tolerance punching operations can actually result in enhanced retention performance.

Referring toFIGS. 39-42, the application of “squirts”1676to affix the left and right side mounting brackets,106and108, respectively to the multi-disc CD player unit104to form the CD player subassembly66, is illustrated. The squirts are preferable die-punch formed simultaneously with the formation of the mounting brackets106/108themselves. It is noted that the brackets106/108can be configured symmetrically, whereby one design can be used for both sides of the CD player unit104, thereby further reducing the overall part count. The squirts1676are preferably formed on relatively regions1678of their associated bracket106/108. A single through passage1680if formed in the planer region1678. Two or more substantially symmetrical forms1682extend radially inwardly from the edge of the through passage1680. Each form1682has a neck region1684and a tapered region or sector1686. The tapered region1686is supported as a cantilever by the neck region1684. The tapered regions1686collectively co-act to define (in the case of two forms) a bisected frustoconical form, wherein each tapered region1686defines an outside peripheral surface1688which are acutely converging upon an axis normal to the planer region1678. The taper of an imaginary cone1700extended from surfaces1688is designated by the angle w. As illustrated by alternative phantom depictions, the overall shape of the imaginary cone1700can be parabolic or hyperbolic. The outer peripheral surface1688of each tapered region or sector1686has a circumferential range designated by the angle θ, which with two forms is preferably in the range of 90°-120°.

In application, the collective outer peripheral surface of the sectors1686engage a surface forming the outer diameter of a recess or through hole1702in an adjacent structure104to which the bracket106/108is to be attached. As illustrated inFIG. 40, the maximum diameter edge surface1704sectors1686effect line contact to maximize pull-out performance.

Referring toFIG. 42, localized radially outwardly projecting knurls, ridges or extensions1706to provide point contacts with the adjacent structures.

Attachment of the squirt1676to an adjacent structures is affected simply by aligning the sector1686with the through hole1702and pressing inwardly, as indicated by the phantom finger tip and resultant force arrow1708.

In essence, the present invention uses a multi-sided fold-up polymer based case or “preform blank”, for the chassis of the radio assembly that is molded in a relatively flat state. During the assembly of the radio, the preform blank is folded into the resultant three dimensional case shape. The sections or wall portions (top, back, bottom and front) of the case are interconnected by a hinge style detail that allows the folding to occur with a snap feature to help secure the sections after folding into the three-dimensional assembly. The shielding and/or grounding may be achieved through using an insert molded wire mesh or a post molding plating process like vacuum metal deposition, as an example. The hinge portion may consist of only wire mesh, or a combination of polymer and wire mesh depending on the polymer capability. If a vacuum metal deposition process is used instead of mesh, the hinge will require special design features outside of the hinge to enable an EMC shield to overcome any potential micro-cracking that may occur in the deposited metal from the fold-up assembly at the hinge point when the walls of the fold-up are in the final assembled position. The shield will be enabled after the detail is in the resultant folded-up shape.

The case has the capability for molded-in details to enhance the assembly with mounting features and snap retention details. Also, this allows for pliable ground details that can interface with the circuit board ground pad areas. The structure of the chassis is provided using two aluminum extrusions on the opposing sides of the radio case. One or both of the extrusions may be used for heat dissipation of the power devices on the circuit board assembly. In the event of a playback mechanism like a CD player is used, the front bracket typically used to secure the mechanism in the audio assembly will also provide the vehicle mounting of the audio assembly. Unlike metal chassis radio assemblies that may use a bottom-up assembly, this approach allows the back wall to be folded up and into place to provide the back of the mechanism stability by driving screws through the wall section into the mechanism. This eliminates an extra metal bracket for securing the CD player often used with other approaches.

The extrusions are assembled to the multi-sided fold-up by loading the extrusions into a molded detail at the back of the case and pivoting the extrusion along molded rails at the top and bottom of the sides to enable an interference fit to the molded rails with the front of the extrusions deflecting molded-in snaps on the front section to reach the final seated position. In this manner, the extrusions act both as a component (side wall) and as their own assembly tool.

The molded multi-sided fold-up polymer based case allows for assembly details as described but offers the advantage of being processed through a less expensive tooling option than a molded box-like case with a frontplate as described in connection withFIG. 3. The fold-up approach tooling does not require side coring and after molding the relatively flat nature of the part enables easier shipping and storage if needed. In the event an insert molded wire mesh is used, the mesh also does not require forming and can simply be cut and loaded, reducing the expenditure for the wire mesh form processing equipment.

The grounding details in the fold-up approach are better suited for interface to the circuit board than the box-style case in that they can be designed to compress against the ground pads and the folding sections can also be enabled with details locally to secure the ground points from the prior section part during the assembly as opposed to trying to provide a slide clearance and not hinder the assembly.

The design detail that enables both flexibility and minimized cost over the box-like case and front plate assembly is that the molding for the fold-up portion is one tool and the extrusions can be the same part reused on each side of the radio case. A part molded in a relatively flat state is both economical for part transportation and storage. The structure for the chassis uses a process based on the incremental strength leveraged from assembling each component part to finalize the structure as a container for the playback mechanism and circuit boards. The interface between the extruded aluminum sides and the molded fold-up offers an interference fit on molded details to help stabilize the structure of the final assembly. This is unique in that typically the extrusion may only be a heat sink for the power devices from the circuit board. This invention enables the extrusion to provide a structural and shielding component in addition to the heat flow function.

Referring toFIG. 44-54, a consolidated radio/CD player apparatus2010embodying many aspects of the present invention is illustrated. The radio/CD player2010is an assemblage of six major components or subassemblies, a generally planer, composite preform blank2012, a circuit board subassembly2014, a CD player subassembly2016, a left side closure member2018, a right side closure member2020and a trim plate subassembly2022. Additionally, an adaptor or mounting bracket2024is pre-attached to the CD player assembly2016by screws2026. As will be described in greater detail hereinbelow, rear wall mounting screws2028are affixed to the CD player2016, rear panel reinforcement screws2030are affixed to the rear edges of the left and right side closure members2018and2020, respectively, and screws2032affix the right side closure member2030to three power devices2032mounted on the circuit board subassembly2014.

It is envisioned that each of the major components/subassemblies would be produced “off-line” and the final assembly process would comprise the efficient, high volume joining of the major components/subassemblies and end-of-line testing of the completed units.

FIGS. 53 and 54depict perspective views of the fully assembled radio/CD player apparatus2010.FIG. 44is an exploded view illustrating the juxtaposition of the respective major components during the assembly process.FIGS. 45-53depict specific assembly steps of the major components as will be described hereinbelow.

As best seen inFIG. 45, the preform blank2012is preferably injection molded of polymer based material in a generally planer configuration and, when finally assembled, forms a box-like, three dimensional case. The blank2012defines a front wall portion2036, a bottom wall portion2038, a rear wall portion2040and a top wall portion2042respectively integrally interconnected by “living hinges” extending along axes designated as X-X, Y-Y and Z-Z, respectively. All of the blank wall portions are integrally formed in a single injection molding process and comprises a composite of a pre-shaped planer piece of wire screen wire insert molded within a layer of relatively rigid polymer material such as glass filled polypropylene. Each of the wall portions is deemed to have a leading edge, a trailing edge and an opposed pair of side edges.

The front wall portion2036has a female engagement feature2044and a pair of female guide features2046integrally formed adjacent the leading edge thereof. Similarly, the top wall portion2042has a male engagement feature2048and a pair of male guide features2050integrally formed adjacent the trailing edge thereof. The trailing edge of the front wall portion2036is interconnected with the leading edge of the bottom wall portion2038along hinge line X-X. The trailing edge of the bottom wall portion2038is interconnected with the leading edge of the rear wall portion2040along hinge line Y-Y. The trailing edge of the rear wall portion2040is interconnected with the leading edge of the top wall portion2042along hinge line Z-Z.

The circuit board subassembly2014, CD player subassembly2016and trim plate subassembly2024are substantially similar to the corresponding major components described hereinabove in connection with the embodiment ofFIG. 3. For the sake of brevity, the details thereof will not be repeated here.

Referring particularly toFIGS. 46-53, a method of assembly of the lightweight audio system2010of the present invention is illustrated. Audio system2010can be assembled manually by an ordered process wherein a single (preferably, but not limited to) operator, who sequentially assembles the six major components or subassemblies on a designated work surface. No specialized tools or separate/dedicated fixtures are required. No threaded fasteners/screws are required. Each or the major components and subassemblies form integral features which cooperate to interact with features of the other components and subassemblies to register, align and guide the components and subassemblies during adjoining thereof as well as to removably affix the components and subassemblies to one another when in their final design position. This process is referred to herein as the Slide-lock Snap-lock™ Screwless Assembly Technology and Method or “SLAT”. In effect, the components “self-fixture” one another in combination. The assembly of the radio/CD player2010is effected by the assembly technician or operator taking the following steps:

Referring toFIG. 46, the trim plate subassembly2022can be affixed to the outer (bottom as depicted) surface of the front wall portion2036by self-aligning, self-engaging engagement features2052. Thus configured, the illustrated subassembly defines rearwardly (upwardly) directed extension pairs2054and2056integrally formed on the inner surface of the front wall portion2036and trim plate subassembly2022, respectively. The inner surface of the bottom wall portion2038defines four integrally formed grounding clips2058and two pedestals2060extending upwardly.

Referring toFIG. 47, the circuit board subassembly2014is inserted downwardly to self-align, self-position and self-engage with guideways formed by the extensions2054. Insodoing, the electrical circuitry contained on the circuit board subassembly2014is electrically interconnected with the circuitry on the trimplate subassembly2022, as well as the other components via registering interconnects and plugs (not illustrated).

Referring toFIG. 48, the CD player subassembly2016is inserted downwardly to self-align, self-position and self-engage with locating pins formed by the extensions2056. Typically, an electrical umbilical (not illustrated) interconnects the CD player subassembly2016and the circuit board subassembly2014.

Referring toFIGS. 49-51, the preform blank2012is then folded, transitioning it from its original generally planer configuration to a three dimensional box-like configuration. Referring toFIG. 49, the first step of folding the preform blank entails manually or mechanically rotating bottom wall portion2038substantially 90° about axis X-X from its original horizontal orientation illustrated inFIG. 48co-planer with the front wall portion2036to a vertical orientation substantially perpendicular or normal with front wall portion2036. Note that in this step, rear wall portion2040and top wall portion2042remain co-planer with bottom wall portion2038, assuming a vertical orientation.

As best viewed inFIG. 47, the inner surface of the bottom wall portion2038has integrally formed inwardly directed guide retainer features2062which, in combination with the grounding clips2058, function to position, secure and electrically ground the circuit board subassembly2014upon final assembly of the radio/CD player apparatus2010. The guide retainer features2062positionally secure the circuit board subassembly2014by engaging side edges and slots2070formed therein.

Inwardly directed, laterally opposed edge retention ribs2072are integrally formed on the inner surface of the rear wall portion2040. Furthermore, integral reinforcing ribs2074extend from the inner surface of the rear wall portion2040to secure a rear integral mounting stud2078extending from the outer surface of the rear wall portion2040. SeeFIG. 50. Similarly, the inner surface of the top wall portion2042has X-shaped reinforcement ribs2076integrally formed on the inner surface thereof to prevent “oil canning”.

Referring toFIG. 50, the second step of folding the preform blank entails manually or mechanically rotating rear wall portion2040substantially 90° about axis Y-Y from its vertical orientation illustrated inFIG. 49co-planer with the bottom wall portion2038to a horizontal orientation substantially parallel with front wall portion2036. Note that in this step, top wall portion2042remains co-planer with rear wall portion2040, assuming a horizontal orientation. Although not illustrated, after completion of the step ofFIG. 50, guide retainers2064serve to abut the rearmost edge surface of the circuit board subassembly2014to effect longitudinal support thereof.

Referring toFIGS. 49,50and54, screws2028are then applied, extending through holes2080formed in the pedestals2060of rear wall portion2040and engaging the rear wall of the CD player subassembly2016, rigidly securing rear wall portion2040and bottom wall portion2038in their respective positions as illustrated inFIG. 50.

Note that during the process of forming the preform blank2012, the screen is stretched, punched or weakened in the areas corresponding with the pedestals2060such as illustrated inFIGS. 37 and 38. Extra screen inserts can be provided within the portions of the mold forming the pedestals or external EMI patches or surface coatings can be provided to ensure complete shielding is provided by the final assembly.

Referring toFIG. 51, the third step of folding the preform blank entails manually or mechanically rotating top wall portion2042substantially 90° about axis Z-Z from its horizontal orientation illustrated inFIG. 50co-planer with the rear wall portion2040to a vertical orientation substantially parallel with bottom wall portion2038. While transitioning from the orientation ofFIG. 50to that ofFIG. 51, the male engagement feature2048and guide features2050extending from the leading edge of the top wall portion2042are respectively guidingly received within the corresponding female engagement feature2044and guide features2046to self-position and self-engage the top wall portion2042. As illustrated inFIG. 51, the perform blank2012has been fully folded into a three-dimensional box-like configuration.

The wire screen/conductive layer is continuous throughout the full extent of the four contiguous wall portions2036,2038,2040and2042, with the exception of where the leading edge of the front wall portion2036adjoins the trailing edge of the top wall portion2042. The slight gap at the point of contact of the front wall portion2036and2042is believed by the inventors to result in only deminimus RF leakage that, if required can be effectively blocked by application of a local conductive patch.

Referring toFIGS. 52,53and54, the application of the left and right side closure members218and220is illustrated. As illustrated inFIG. 52, the rear edge portions of closure members are initially angularly positioned under their respective retention rib2072and then pivoted thereabout to assume the final, installed position illustrated inFIG. 53. As the side closure members2020and2022are fully installed, the forward edges thereof are retained in the installed position by self-engaging retention features2082integrally formed on the rear surface of the front wall portion2036. Thereafter, screws2032are applied through holes in the right side closure member2020to engage their respective power devices2034to establish the right side closure member2020an a heat sink. After this step, final assembly is essentially complete.

As best viewed inFIG. 52, the side closure members2018and2020are identical, formed from a continuous extrusion process, having a typical cross-section defining inwardly directed upper channels2086, lower channels2088and center channels2090. During installation, each upper channel2086forms an interference fit with a respective edge portion of the top wall portion2042. Similarly, each lower channel2088forms an interference fit with a respective edge portion of the bottom wall portion2038. Redundant retention can be applied by screws2030which extend through mating holes formed in the front and rear wall portions2036and2042, to engage the adjacent center channel2090.

Referring toFIG. 55, the exposed edges or alternatively, a molded rail, of the top wall portion2042and bottom wall portion2038have a series of openings2092exposing the screen2084. The exposed segments of screen have an upward/downward extending dome or distension2094locally raising the screen above the outer surface of the adjacent wall portion. Once installed, the inner surfaces of the channels2086and2088compressively engage the screen domes2094to establish reliable, multi-point electrical contact therebetween.

Referring toFIGS. 55-57, detail of one of the “living hinges” is illustrated. Adjacent edges of the bottom wall portion2038and rear wall portion2040are slightly spaced apart to expose electrically conductive material such as screen2084extending along the hinge axis Y-Y. This arrangement assures that each of the wall panels remain substantially rigid while the hinge portions are relatively flexible, and maintains its EMI isolation characteristics.

Referring toFIGS. 55 and 56, preferably, at each end of each living hinge is a relatively this web of plastic2096integrally interconnecting the adjacent wall portions2038and2040to provide torsional rigidity to the hinge, as well as the overall housing assembly.

Air flow openings2098are formed in the top and bottom wall portions closed by screen2084while permitting free ventilation of the interior of the housing assembly.

Referring toFIG. 57, all cut edges2100of the screen2084are fully encased in a layer of plastic2102to prevent unraveling of the screen2084and/or inadvertent electrical shorts or injury to an assembly technician.

Referring toFIGS. 58 and 59, an alternative hinge design2104is illustrated. Adjacent edges of a first wall portion2106and a second wall portion2108are integrally interconnected by a thin web2110of plastic material. In this embodiment, the inner surfaces of both wall portions2106and2108are coated by an electrically conductive surface layer (not illustrated). A similar web with wire mesh is depicted inFIG. 19above. A series of spaced retention hooks2112are integrally formed on the first wall portion2160extending adjacently along the hinge line/axis. A cooperating retention rib2114is integrally formed on the second wall portion2108extending adjacently parallel to the hinge line/axis. The hooks2112and cooperating rib2114are dimensioned to cooperatively self-engage one another as the wall portions2016and2018are transitioned from the co-planer orientation depicted inFIG. 58to the right angle configuration depicted inFIG. 59. This embodiment ensures robust continuous electrical interconnection between the adjacent conductive layers, even in the case of micro-cracking during the folding process.

Insert molded wire mesh in plastic has been successful for replacing metal enclosures typically utilized for packaging electronics that require EMC shielding and grounding. Virtually any plastic resin can be molded with a wire mesh which makes it advantageous for almost any application requiring these unique characteristics that offer many assembly and weight reductions that are the result of replacing metal enclosures with a molded plastic version. A limiting factor with some plastic resins is the ability for dimensional stability and especially warpage characteristics that may be a hindrance to the final molded part to meet the same requirements as a similar metal version. As an example, some plastic resins like polypropylene may tend to warp during the cooling phase after mold ejection which can disrupt the dimension stability. This may, in turn, threaten the ability of the part to mate with conjoining component parts in an assembly.

By using a nozzle injected gas product like the MuCell process (offered by Trexel) for the insert molded part operation, the wire mesh insert molding can be fabricated to offer a dimensionally stabilized part that is resistant to warpage that is now better suited for the assembly of the electronics enclosure. Without the process, additional fixtures or clamping may be necessary to prevent post molding warpage or creep of the material due to non-uniform cooling that can take place after the part is molded and ejected from the tool. This is critical for use with the wire mesh in plastic molding with electronic enclosures to prevent unwanted wire mesh contact with electrical contacts due to warpage or dimensional variation. This also allows interface contact between assembly parts to be aligned within normal material tolerance eliminating the need to construct additional controls into the parts and/or molding.

Referring toFIGS. 24 and 25, an injection molding machine or extruder1188can be modified to accommodate nitrogen gas injection via an injector1189to implement the MuCell process. As a result, the resulting molded or extruded plastic parts are filled with micro-bubbles of nitrogen gas1167whereby the flow of the molten plastic within the mold in enhanced, reducing warpage and improving part-to-part repeatability. Furthermore, the process further reduces weight of the molded parts and reduces the required tonnage of the molding machine.

It is to be understood that the invention has been described with reference to specific embodiments and variations to provide the features and advantages previously described and that the embodiments are susceptible of modification as will be apparent to those skilled in the art.

Furthermore, it is contemplated that many alternative, common inexpensive materials can be employed to construct the basis constituent components. Accordingly, the forgoing is not to be construed in a limiting sense.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, a number of the various radio/CD player case constructions illustrated herein are illustrated as being formed of solid molded polymer material for the sake of simplicity and clarity of understanding. It is to be understood, however, that the wire mesh depicted, for example inFIG. 93, can be employed in the other configurations and embodiments with equal success. Furthermore, several of the housing assembly structures are described herein as being formed of metal. However, a wide range of material substitutes, including plastics, ceramics, non-ferrous metals and composites can be substituted without departing from the spirit and scope of the present invention. The terms “snap-engaging” and “self-engaging” are intended to interpreted very broadly inasmuch as innumerable structural, process (e.g. weldments) and chemical (e.g. adhesives) equivalents are available. In addition “squirts”, as described in connection withFIGS. 39-42hereinabove can be employed to replace the screws2026,2030and2032, inter alia, to further reduce part count and reduce the chances of mis-assembly. It is, therefore, to be understood that within the scope of the appended claims, wherein reference numerals are merely for illustrative purposes and convenience and are not in any way limiting, the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents, may be practiced otherwise than is specifically described.