Patent Publication Number: US-2018039306-A1

Title: Handheld computing device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of, and claims the benefit of priority under 35 U.S.C. § 120 to, co-pending U.S. patent application Ser. No. 14/242,704, filed Apr. 1, 2014, entitled “HANDHELD COMPUTING DEVICE,” which is a Continuation of U.S. patent application Ser. No. 13/561,886, filed Jul. 30, 2012, entitled “HANDHELD COMPUTING DEVICE,” now U.S. Pat. No. 8,726,488, which issued on May 20, 2014, which is a continuation of U.S. patent application Ser. No. 12/685,463, filed Jan. 11, 2010, entitled “HANDHELD COMPUTING DEVICE,” now U.S. Pat. No. 8,264,820, which issued on Sep. 11, 2012, which is a Continuation of U.S. patent application Ser. No. 12/395,570, filed Feb. 27, 2009, entitled “HANDHELD COMPUTING DEVICE,” now U.S. Pat. No. 7,649,744, which issued Jan. 19, 2010, which is a Divisional of U.S. patent application Ser. No. 10/884,172, filed Jul. 2, 2004, entitled “HANDHELD COMPUTING DEVICE,” now U.S. Pat. No. 7,515,431, which issued Apr. 7, 2009, all of which are hereby incorporated herein by reference. 
     This application is also related to the following United States Patent Applications, all of which are hereby incorporated herein by reference: U.S. patent application Ser. No. 12/412,108, filed Mar. 26, 2009, entitled “HANDHELD COMPUTING DEVICE,” now U.S. Pat. No. 7,839,646, issued Nov. 23, 2010; U.S. patent application Ser. No. 29/196,832, filed Jan. 5, 2004, entitled “MEDIA DEVICE,” now abandoned; U.S. patent application Ser. No. 10/643,256, filed Aug. 18, 2003, entitled “MOVABLE TOUCH PAD WITH ADDED FUNCTIONALITY,” now U.S. Pat. No. 7,499,040, issued Mar. 3, 2009; U.S. patent application Ser. No. 10/188,182, filed Jul. 1, 2002, entitled “TOUCH PAD FOR HANDHELD DEVICE,” now U.S. Pat. No. 7,046,230, which issued May 16, 2006; U.S. application Ser. No. 10/722,948, filed Nov. 25, 2003, entitled “TOUCH PAD FOR HANDHELD DEVICE,” now U.S. Pat. No. 7,495,659, which issued Feb. 24, 2009 and U.S. application Ser. No. 10/423,490, filed Apr. 25, 2003, entitled “MEDIA PLAYER SYSTEM,” now U.S. Pat. No. 7,627,343, which issued Dec. 1, 2009. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to portable computing devices. More particularly, the present invention relates to enclosures of portable computing devices and methods of assembling portable computing devices. 
     2. Description of the Related Art 
     In recent years, portable computing devices such as laptops, PDAs, media players, cellular phones, etc., have become small, light and powerful. One factor contributing to this phenomenon is in the manufacturer&#39;s ability to fabricate various components of these devices in smaller and smaller sizes while in most cases increasing the power and or operating speed of such components. Unfortunately, the trend of smaller, lighter and powerful presents a continuing design challenge in the design of some components of the portable computing devices. 
     One design challenge associated with the portable computing devices is the design of the enclosures used to house the various internal components of the portable computing devices. This design challenge generally arises from two conflicting design goals—the desirability of making the enclosure lighter and thinner, and the desirability of making the enclosure stronger and more rigid. The lighter enclosures, which typically use thinner plastic structures and fewer fasteners, tend to be more flexible and therefore they have a greater propensity to buckle and bow when used while the stronger and more rigid enclosures, which typically use thicker plastic structures and more fasteners, tend to be thicker and carry more weight. Unfortunately, increased weight may lead to user dissatisfaction, and bowing may damage the internal parts of the portable computing devices. 
     Furthermore, in most portable computing devices, the enclosures are mechanical assemblies having multiple parts that are screwed, bolted, riveted, or otherwise fastened together at discrete points. For example, the enclosures typically have included an upper casing and a lower casing that are placed on top of one another and fastened together using screws. These techniques typically complicate the housing design and create aesthetic difficulties because of undesirable cracks, seams, gaps or breaks at the mating surfaces and fasteners located along the surfaces of the housing. For example, a mating line surrounding the entire enclosure is produced when using an upper and lower casing. Not only that, but assembly is often a time consuming and cumbersome process. For example, the assembler has to spend a certain amount of time positioning the two parts and attaching each of the fasteners. Furthermore, assembly often requires the assembler to have special tools and some general technical skill. 
     Another design challenge is in techniques for mounting structures within the portable computing devices. Conventionally, the structures have been laid over one of the casings (upper or lower) and attached to one of the casings with fasteners such as screws, bolts, rivots, etc. That is, the structures are positioned in a sandwich like manner in layers over the casing and thereafter fastened to the casing. This methodology suffers from the same drawbacks as mentioned above, i.e., assembly is a time consuming and cumbersome. 
     In view of the foregoing, there is a need for improved enclosures for portable computing devices. Particularly, enclosures which are more cost effective, smaller, lighter, stronger and aesthetically more pleasing than current enclosure designs. In addition, there is a need for improvements in the manner in which structures are mounted within the enclosures. For example, improvements that enable structures to be quickly and easily installed within the enclosure, and that help position and support the structures in the enclosure. 
     SUMMARY OF THE INVENTION 
     The invention relates, in one embodiment, to a handheld computing device. The computing device includes a seamless enclosure formed from an extruded tube. The extruded tube includes open ends and internal rails which serve as a guide for slidably assembling a user interface assembly through the open ends of the extruded tube, a reference surface for positioning the user interface assembly relative to an access opening in the seamless enclosure, and a support structure for supporting the user interface assembly during use. 
     The invention relates, in another embodiment, to a method of assembling a handheld computing device. The method includes providing an enclosure formed from an extruded tube including open ends and internal rails. The method also includes providing operational components for performing operations associated with the handheld computing device. The method further includes inserting the operational components into the extruded tube through an open end of the extruded tube. The operational components slide along the internal rail during insertion. The internal rails also help to locate the operational components in their desired position within the extruded tube. The method additionally includes securing the operational components to the extruded tube. 
     The invention relates, in another embodiment, to a handheld music player. The hand held music player includes an elongated extruded tube extending along a longitudinal axis, and having a first open end and a second open end opposite the first open end. The elongated extruded tube defines an internal lumen which is sized and dimensioned for slidable receipt of operational components of the handheld music player. The lumen includes rails for guiding the operational components to their desired position within the lumen. 
     The invention relates, in another embodiment, to a handheld computing device. The handheld computing device includes a seamless enclosure having a substantially planar front surface. The planar front surface is configured to present a user interface sub system of the handheld device. The seamless enclosure is formed from an extruded tube having open ends and internal rails. The open ends are configured to receive the user interface sub system therethrough during assembly of the handheld device. The internal rails are configured to locate the user interface sub system in its desired position relative to the planar front surface of the enclosure during assembly of the handheld computing device. 
     The invention relates, in another embodiment, to a method of manufacturing a handheld computing device. The method includes forming an enclosure for the handheld device. The formation includes at least extruding a tube with a substantially planar surface and internal rails and cutting the tube to a desired length where the cutting operation produces openings at each end of the tube. The method also includes forming one or more holes in the substantially planar surface. The method further includes inserting a display assembly into the tube through one of the openings. The display assembly includes a substantially planar printed circuit board and a display. The printed circuit board slides along the internal rails during insertion. The internal rails locate the display behind a first hole and adjacent the planar surface of the tube. The method additionally includes inserting a planar input device into the tube through one of the openings. The planar input device slides along the internal rails during insertion. The internal rails locate the input device behind a second hole and adjacent the planar surface of the tube. 
     The invention relates, in another embodiment, to a planar retaining plate. The retaining plate includes a body. The retaining plate also includes a first set of flexure arms extending from a first side of the body and a second set of flexure arms extending from a second side of the body opposite the first side. Each of the flexure arms are configured for insertion into a different slot located on a device enclosure in order to secure the retaining plate to the device enclosure. The retaining plate serves as a reference surface to various components located internal or external to the device enclosure. 
     The invention relates, in another embodiment, to an interface assembly of a handheld computing device. The handheld computing device has an enclosure and a first electronic device contained therein. The interface assembly includes a printed circuit board (PCB) divided into a flexure portion, a first base portion and a second base portion. The flexure portion is positioned between the first and second base portions. The flexure portion allows the first base portion to move relative to the second base portion. The second base portion is attached to the first electronic device. The interface assembly also includes a second electronic device attached to the first base portion, and operatively coupled to the first electronic device. The interface assembly further includes a support plate attached to the second electronic device. The flexure portion is configured to flex so that the first base portion shifts relative to the second base portion thereby allowing the plate to be correctly aligned with the enclosure during assembly of the handheld computing device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  is an exploded perspective diagram of an electronic device, in accordance with one embodiment of the present invention. 
         FIG. 2  is a perspective diagram of a handheld computing device, in accordance with one embodiment of the present invention. 
         FIG. 3A  is a diagram of an assembled hand held computing device, in accordance with one embodiment of the present invention. 
         FIG. 3B  is a diagram of the hand held computing device of  FIG. 3A  in its unassembled form, in accordance with one embodiment of the present invention. 
         FIG. 4  is top view diagram, in cross section, of an assembled hand held computing device, in accordance with one embodiment of the present invention. 
         FIG. 5  is bottom view diagram, in cross section, of the assembled hand held computing device, in accordance with one embodiment of the present invention. 
         FIGS. 6A-6C  show the insertion and mounting of an input assembly inside a seamless enclosure, in accordance with one embodiment of the present invention. 
         FIGS. 7A and 7B  show a bottom plate in its unassembled and assembled positions, in accordance with one embodiment of the present invention. 
         FIGS. 8A-8C  are diagrams illustrating the audio subassembly in accordance with one embodiment of the present invention. 
         FIG. 9A  is a front perspective view of a seamless enclosure, in accordance with one embodiment of the present invention. 
         FIG. 9B  is a rear perspective view of a seamless enclosure, in accordance with one embodiment of the present invention. 
         FIG. 9C  is a front view of a seamless enclosure, in accordance with one embodiment of the present invention. 
         FIG. 9D  is a rear view of a seamless enclosure, in accordance with one embodiment of the present invention. 
         FIG. 9E  is a top view of a seamless enclosure, in accordance with one embodiment of the present invention. 
         FIG. 9F  is a bottom view diagram of a seamless enclosure, in accordance with one embodiment of the present invention. 
         FIG. 9G  is a right side view of a seamless enclosure, in accordance with one embodiment of the present invention. 
         FIG. 9H  is a left side view of a seamless enclosure, in accordance with one embodiment of the present invention. 
         FIG. 10  is a method of manufacturing an electronic device, in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention generally pertains to portable computing devices and more particularly to components of and methods for assembling portable computing devices. One aspect of the invention relates to a seamless enclosure that includes open ends and internal rails which serve as a guide for slidably assembling the internal components of the portable computing devices through the open ends of the seamless enclosure, as well as positioning and supporting the internal components in their assembled position within the seamless enclosure. The seamless enclosure may for example be formed via an extrusion process. Another aspect of the invention relates to a planar retaining plate, which serves as a multi-positional reference surface to various components of the portable computing devices. The retaining plate may for example be assembled within the lumen of the seamless enclosure to provide a reference surface to internal and external parts of the portable computing device. Another aspect of the invention relates to assemblies capable of flexing in order to align interfacing parts. For example, aligning a plate within the lumen of the seamless enclosure. Yet another aspect of the invention relates to a method of manufacturing a portable computing device. The method may include extruding a tube with a substantially planar surface and internal rails, cutting the tube to a desired length, forming one or more access openings in the substantially planar surface, sliding the user interface assembly along the internal rails into the tube, and thereafter locating and supporting the user interface assembly behind an access opening and adjacent the planar surface of the tube via the internal rails. 
     These and other embodiments of the invention are discussed below with reference to  FIGS. 1-10 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the invention extends beyond these limited embodiments. 
       FIG. 1  is an exploded perspective diagram of an electronic device  50 , in accordance with one embodiment of the present invention. The device  50  may be sized for one-handed operation and placement into small areas such as a pocket, i.e., the device  50  can be a handheld pocket sized electronic device. By way of example, the electronic device  50  may correspond to a computer, media device, telecommunication device and/or the like. 
     The device  50  includes a housing  52  that encloses and supports internally various electrical components (including for example integrated circuit chips and other circuitry) to provide computing operations for the device  50 . The housing  52  also defines the shape or form of the device  50 . That is, the contour of the housing  52  may embody the outward physical appearance of the device  50 . The housing  52  generally includes a main body  54  in the form of an integral tube. By integral, it is meant that the main body is a single complete unit. By being integrally formed, the main body has a substantially seamless appearance, which is unlike conventional housings, which include two parts that are fastened together thereby forming a seam therebetween. Because of the tube like configuration, the main body  54  defines a cavity  56  therethrough between a first open end  58  and second open end  60  located opposite the first open end  58 . The main body  54  also includes one or more windows  62 , which provide access to the electrical components, particularly the user interface elements, when they are assembled inside the cavity  56  of the main body  54 . 
     In order to seal the main body  54 , the housing  52  additionally includes a pair of end caps  64 A and  64 B. Each of end caps  64 A and  64 B is configured to cover one of the open ends  58  or  60  thereby forming a fully enclosed housing system. The end caps  64 A and  64 B may be formed from similar or different materials as the main body  54 . Furthermore, the end caps  64 A and  64 B may be attached to the main body  54  using a variety of techniques, including but not limited to, fasteners, glues, snaps, and/or the like. In some cases, the end caps  64  may be positioned on the surface of the open ends  58  and  60 . If so, they typically have the same shape as the outer periphery of the main body  54 . In order to eliminate gaps, cracks or breaks on the front and side surfaces, the end caps  64 A and  64 B may alternatively be placed inside the cavity  56  at each of the ends. In this arrangement, the outer periphery of the end cap  64 A and  64 B generally matches the inner periphery of the main body  54 . This implementation is typically preferred in order to form a housing  52  with a uniform and seamless appearance, i.e., no breaks when looking directly at the front, back or side of the housing. 
     The cross sectional shape, including both the outer and inner shapes, of the main body  54  may be widely varied. They may be formed from simple or intricate shapes whether rectilinear and/or curvilinear. For hand held devices, it is typically preferred to use a shape that better fits the hand (e.g., form fits). By way of example, a rectangle with curved edges or an oval or pill shaped cross section having curvature that more easily receives the hand may be used. It should be noted that the inner cross sectional shape may be the same or different from the external cross sectional shape of the main body. For example, it may be desirable to have a pill shaped external and a rectangularly shaped interior, etc. In addition, although not a requirement, the front surface of the main body  54  may be substantially planar for placement of the user interface of the device  50 . 
     The device  50  also includes one or more electronic subassemblies  66 A and  66 B. The subassemblies  66  each include a carrier  68 A and  68 B and one or more operational components of the electronic device  50 . The carriers  68 A and  68 B provide a structure for carrying the operational components  70 A and  70 B and supporting them when assembled inside the housing  52 . By way of example, the carriers  68 A and  68 B may be formed from plastics, metals and/or a printed circuit board (PCB). The operational components  70 A and  70 B, on the other hand, perform operations associated with the computing device  50 . The operational components may for example include user interface elements  70 A and/or circuit elements  70 B. The user interface elements  70 A allow a user to interact with the computing device  50 . By way of example, the user interface elements  70 A may correspond to a display and/or an input device such as a keypad, touch pad, touch screen, joystick, trackball, buttons, switches and/or the like. The circuit components  70 B, on the other hand, perform operations such as computing operations for the computing device  50 . By way of example, the computing components  70 B may include a microprocessor, memory, hard drive, battery, I/O connectors, switches, power connectors, and/or the like. 
     During assembly, the subassemblies  66 A and  66 B are positioned inside the cavity  56  of the main body  54 . In particular, the subassemblies  66 A and  66 B are inserted into one of the open ends  58  or  60  of the main body  54  mainly along a longitudinal axis  74  of the main body  54  to their desired position within the housing  52 . Once positioned inside the cavity  56 , the end caps  64 A and  64 B of the housing  52  may be attached to the main body  54  in order to fully enclose the housing  52  around the subassemblies  66 A and  66 B. In most cases, the user interface elements  70 A are positioned relative to the window opening  62  so that a user may utilize the user interface elements  70 A. By way of example, the window  62  may allow viewing access to a display or finger access to a touch pad or button. 
     In order to more efficiently assemble the electronic subassemblies  66 A and  66 B inside the cavity  56 , the device  50  includes an internal rail system  78  disposed inside the cavity  56  of the main body  54 . In most cases, the internal rail system  78  is integrally formed with the main body  54 , i.e., formed as a single part. The internal rail system  78  is configured to receive the various subassemblies  66 A and  66 B and guide them to their desired position within the main body  54  when the subassemblies  66 A and  66 B are inserted through one of the open ends  58  or  60 . The internal rail system  78  enables the subassemblies  66 A and  66 B to be easily and quickly assembled within the device  50 . For example, the rail system  78  provides for insertion (or removal) with minimal effort and without tools. The internal rail system  78  also helps support and store the subassemblies  66 A and  66 B in an organized manner within the device  50 . By way of example, the rail system  78  may store the subassemblies  66 A and  66 B in a stacked parallel arrangement thereby using available space more efficiently. 
     As shown, the rail system  78  includes at least one set of opposed rails  80 , each of which extends longitudinally through the cavity  56  and each of which protrudes from the inner sides of the main body  54 . The rails  80  are configured to receive the subassemblies  66 A and  66 B and cooperate to guide subassemblies  66 A and  66 B to their desired position within the housing  52 . The internal rails  80  generally allow the subassemblies  66 A and  66 B to be slid into the cavity  56  through the open ends  58  or  60  following the longitudinal axis  74  of the main body  54 . That is, the subassemblies  66 A and  66 B and more particularly the carriers  68 A and  68 B are capable of sliding in and out of the housing  52  along one or more surfaces of the rails  80 . 
     The portion of the subassemblies  66 A and  66 B that engages the rails  80  may be a surface of the subassemblies or alternatively one or more posts or mounts that extend outwardly from the subassemblies  66 A and  66 B. Furthermore, the reference surfaces for the opposed rails  80  may be positioned in the same plane or they may be positioned in different planes. The configuration generally depends on the configuration of the subassemblies  66 A and  66 B. By way of example, in some cases, the subassemblies  66 A and  66 B may have a cross section that is stepped rather than completely planar. In cases such as these, the opposed rails  80  have references surfaces in different planes in order to coincide with the stepped cross section. Moreover, although typically continuous between the ends, each of the rails  80  may be segmented or include removed portions as for example at the ends for placement of the flush mounted end caps. 
     The width of the rails  80  may be widely varied. For example, they may be one integral piece that extends entirely from one side to the other, or they may be separate pieces with a gap located therebetween (as shown). The position and cross sectional dimensions and shapes of each of the rails may also be widely varied. The size and shape as well as the position of the rails  80  generally depends on the configuration of the subassemblies  66 A and  66 B. The rails  80  may have the same shape and size or they may have different shape and size. In most cases, the size and shape is a balance between keeping them as small as possible (for weight and space requirements) while providing the required reference surface and ample support to the subassemblies  66 A and  66 B. 
     To elaborate, the rails  80  define one or more channels  82 A and  82 B that receive the one or more subassemblies  66 A and  66 B. In the illustrated embodiment, the rails  80  along with the main body  54  define a pair of channels, particularly an upper channel  82 A and a lower channel  82 B. The upper channel  82 A receives a first subassembly  66 A and the lower channel  8 B receives a second subassembly  66 B. It should be noted, however, that this is not a limitation and that additional sets of rails  80  may be used to produce additional channels  82 . It should also be noted that although only one subassembly  66  is shown for each channel  82  this is not a requirement and that more than one subassembly  66  may be inserted into the same channel  82 . Moreover, it should be noted that the subassemblies are not limited to being fully contained with a single channel and that portions of a subassembly may be positioned in multiple channels. For example, the second subassembly  66 B, which is positioned in the lower channel  82 B, may include a protruding portion that is positioned through the rails  80  and into the upper channel  82 A. 
     The channels  82 A and  82 B generally include an entry point and a final point. The entry point represents the area of the channel  82  that initially receives the subassemblies  66 A and  66 B, i.e., the area proximate the ends of the main body  54 . The final point, on the other hand represents the area of the channel  82  that prevents further sliding movement. The final point may for example set the final mount position of the subassemblies  66 A and  66 B within the housing  52 . The final point may for example correspond to an abutment stop. The abutment stop may be integral with the main body  54  or a separate component. By way of example, the abutment stop may correspond to one more posts that are mounted inside the cavity  56  on the inside surface of the main body  54  at a predetermined distance along the longitudinal axis  74 . 
     In order to prevent the subassemblies  66 A and  66 B from sliding once assembled, the interface between the subassemblies  66 A and  66 B and housing  52  may include a locking or securing mechanism. The locking mechanism generally consists of two parts, a housing side locking feature and a subassembly side locking feature that are cooperatively positioned so that when the subassembly  66 A or  66 B is inserted into the housing  52 , the locking features engage with one another thus holding the subassembly  66 A or  66 B in its desired position within the housing  52 . In most cases, the locking features are configured to provide quick and easy assembly of the subassembly into the housing without the use of tools. The locking features may correspond to snaps, friction couplings, detents, flexures and/or the like. Alternatively or additionally, the subassemblies  66  may be attached to the main body  54  with fasteners or adhesives. 
     In the illustrated embodiment, the subassemblies  66  each include a flexure tab  88  that engages a recess  90  located on an inner surface of the main body  54 . When the subassembly  66  is slid into the housing  52 , the tab  88  snaps into the recess  90  thereby securing the subassembly  66  at a predetermined position along the longitudinal axis  74 . That is, because the tabs  88  flex, they allow the subassemblies  66  to pass when pushed into the cavity  56 . When the subassemblies  66  pass over the recess  90 , the tabs  88  resume their natural position thereby trapping the subassemblies  66  in the channel  82  between the locking tab/recess  88 / 90  and the abutment stop at the end of the channel  82 . Using this arrangement, the subassemblies  66  are prevented from sliding out of the channels  82  on their own. In order to remove the subassembly  66 , a user simply lifts the tab  88  away from the recess  90  while pulling on the subassembly  66 . The recess  90  and abutment stop may cooperate to set the final position of the subassembly  66  in the cavity  56  of the main body  54 . For example, the recess and abutment stop may be configured to position the user interface elements  70 A directly behind the window opening  62  so that a user has full access to the user interface elements  70 A. 
     In accordance with one embodiment, the main body  54  including the internal rails  80  is formed via an extrusion process. The extrusion process is capable of producing an integral tube without seams, crack, breaks, etc. As is generally well known, extrusion is a shaping process where a continuous work piece is produced by forcing molten or hot material through a shaped orifice, i.e., the extrusion process produces a length of a particular cross sectional shape. The cross sectional shape of the continuous or length of work piece is controlled at least in part on the shaped orifice. As the shaped work piece exits the orifice, it is cooled and thereafter cut to a desired length. As should be appreciated, the extrusion process is a continuous high volume process that produces intricate profiles and that accurately controls work piece dimensions (which can be a necessity for smaller parts). Furthermore, because extrusion has low tooling costs, it is relatively in expensive when compared to other forming or manufacturing processes. 
     The main body  54  may be formed from a variety of extrudable materials or material combinations including but not limited to metals, metal alloys, plastics, ceramics and/or the like. By way of example, the metals may correspond to aluminum, titanium, steel, copper, etc., and the plastic materials may correspond to polycarbonate, ABS, nylon, etc. The material selected generally depends on many factors including but not limited to strength (tensile), density (lightweight), strength to weight ratio, corrosion resistance, formability, finishing, recyclability, tooling costs, and/or the like. The material selected may also depend on electrical conductivity, thermal conductivity, combustability, toxicity, and/or the like. 
     In one particular embodiment, the main body  54  including the internal rails  80  is formed from an extruded aluminum tube. Some of the reasons for using aluminum over other materials is that it is light weight and structurally stronger (e.g., it has very good mechanical properties and strength to weight ratio). This is especially important for hand held devices. Other reasons for using aluminum include: reduced tooling costs (e.g., injection moldings can be cost prohibitive), it is easily formable and extruded in a wide variety of shapes including hollow parts, easily machinable thus making it easy to alter the part after the extrusion process, provides a near net shape, offers superior corrosion resistance, it has high scrap value and is routinely reprocessed to generate new extrusions, and it can be finished using a variety of methods including mechanical and chemical prefinishes, anodic coatings, paints and electroplated finishes. 
       FIG. 2  is a perspective diagram of a handheld computing device  100 , in accordance with one embodiment of the present invention. By way of example, the computing device  100  may generally correspond to the device  50  shown and described in  FIG. 1 . The computing device  100  is capable of processing data and more particularly media such as audio, video, images, etc. By way of example, the computing device  100  may generally correspond to a music player, game player, video player, camera, cell phone, personal digital assistant (PDA), and/or the like. With regards to being handheld, the computing device  100  can be operated solely by the user&#39;s hand(s), i.e., no reference surface such as a desktop is needed. In some cases, the handheld device is sized for placement into a pocket of the user. By being pocket sized, the user does not have to directly carry the device and therefore the device can be taken almost anywhere the user travels (e.g., the user is not limited by carrying a large, bulky and heavy device). In the illustrated embodiment, the computing device  100  is a pocket sized hand held music player that allows a user to store a large collection of music. By way of example, the music player may correspond to the iPod series MP3 players, and more particularly the iPod mini manufactured by Apple Computer of Cupertino, Calif. 
     As shown, the computing device  100  includes a housing  102  that encloses and supports internally various electrical components (including integrated circuit chips and other circuitry) to provide computing operations for the device. The integrated circuit chips and other circuitry may include a microprocessor, hard drive, Read-Only Memory (ROM), Random-Access Memory (RAM), a battery, a circuit board, and various input/output (I/O) support circuitry. In addition to the above, the housing  102  may also define the shape or form of the device  100 . In this particular embodiment, the housing  102  extends longitudinally and has a pill like cross section. The size and shape of the housing  102  is preferably dimensioned to fit comfortably within a user&#39;s hand. In one particular embodiment, the housing is formed from an extruded material such as aluminum thereby providing a seamless look along the length of the device  100 . That is, unlike conventional housings, the housing  102 , particularly the main body, does not include any breaks between the top and bottom ends thereby making it stronger and more aesthetically pleasing. 
     The computing device  100  also includes a display screen  104 . The display screen  104 , which is assembled within the housing  102  and which is visible through an opening  106  in the housing  102 , is used to display a graphical user interface (GUI) as well as other information to the user (e.g., text, objects, graphics). By way of example, the display screen  104  may be a liquid crystal display (LCD). In some cases, the housing  102  may include a window, which is positioned in the opening in front of the display in order to protect the display from damage. The window is typically formed from a clear material such as clear polycarbonate plastic. 
     The computing device  100  also includes one or more input devices  108  configured to transfer data from the outside world into the computing device  100 . The input devices  108  may for example be used to perform tracking/scrolling, to make selections or to issue commands in the computing device  100 . By way of example, the input devices  108  may correspond to keypads, joysticks, touch screens, touch pads, track balls, wheels, buttons, switches, and/or the like. In the illustrated embodiment, the computing device  100  includes a touch pad  108 A and one or more buttons  108 B, which are assembled within the housing  102  and which are accessible through a second opening  110  in the housing  102 . 
     The touch pad  108 A generally consists of a touchable outer surface  111  for receiving a finger for manipulation on the touch pad  108 A. Although not shown, beneath the touchable outer surface  111  is a sensor arrangement. The sensor arrangement includes a plurality of sensors that are configured to activate as the finger passes over them. In the simplest case, an electrical signal is produced each time the finger passes a sensor. The number of signals in a given time frame may indicate location, direction, speed and acceleration of the finger on the touch pad, i.e., the more signals, the more the user moved his or her finger. In most cases, the signals are monitored by an electronic interface that converts the number, combination and frequency of the signals into location, direction, speed and acceleration information. This information may then be used by the device  100  to perform the desired control function on the display screen  104 . 
     The position of the touch pad  108 A relative to the housing  102  may be widely varied. For example, the touch pad  108 A may be placed at any external surface (e.g., top, side, front, or back) of the housing  102  that is accessible to a user during manipulation of the device  100 . In most cases, the touch sensitive surface  111  of the touch pad  108 A is completely exposed to the user. In the illustrated embodiment, the touch pad  108 A is located in a lower, front area of the housing  102 . Furthermore, the touch pad  108 A may be recessed below, level with, or extend above the surface of the housing  102 . In the illustrated embodiment, the touch sensitive surface  111  of the touch pad  108 A is substantially flush with the external surface of the housing  102 . 
     The shape of the touch pad  108 A may also be widely varied. For example, the touch pad  108 A may be circular, rectangular, square, oval, triangular, and the like. In the illustrated embodiment, the touch pad  108 A is circular. Circular touch pads allow a user to continuously swirl a finger in a free manner, i.e., the finger can be rotated through 360 degrees of rotation without stopping. Furthermore, the user can rotate his or her finger tangentially from all sides thus giving it more range of finger positions. For example, when the device  100  is being held, a left handed user may choose to use one portion of the touch pad  108 A while a right handed user may choose to use another portion of the touch pad  108 A. More particularly, the touch pad is annular, i.e., shaped like or forming a ring. When annular, the inner and outer perimeter of the shaped touch pad defines the working boundary of the touch pad. 
     The buttons  108 B are configured to provide one or more dedicated control functions for making selections or issuing commands associated with operating the device  100 . By way of example, in the case of a music player, the button functions may be associated with opening a menu, playing a song, fast forwarding a song, seeking through a menu and the like. In most cases, the button functions are implemented via a mechanical clicking action although they may also be associated with touch sensing similar to the touch pad  108 A. The position of the buttons  108 B relative to the touch pad  108 A may be widely varied. For example, they may be next to one another (center or peripheral), spaced apart or integrated into a single unit. Several touch pad/button arrangements, which may be used in the device  100 , are described in greater detail in pending Pat. App. Ser. Nos.: 10/643,256, 10/188,182, 10/722,948, which are all herein incorporated by reference. 
     The computing device  100  also includes one or more switches  112  including power switches, hold switches, and the like. The power switch is configured to turn the device  100  on and off, and the hold switch is configured to activate or deactivate the touch pad  108 A and/or buttons  108 B. This is generally done to prevent unwanted commands by the touch pad  108 A and/or buttons  108 B, as for example, when the device  100  is stored inside a user&#39;s pocket. Like the touch pad  108 A and buttons  108 B, the switches  112  are accessible through a third opening  114  in the housing  102 . 
     The device  100  may also include one or more connectors  116  for transferring data and/or power to and from the device  100 . In the illustrated embodiment, the device  100  includes an audio jack  116 A, a data port  116 B and a power port  116 C. The audio jack  116 A allows audio information to be outputted from the device  100 . The data port  116 B allows data to be transmitted and received to and from a host device such as a general purpose computer (e.g., desktop computer, portable computer). The data port  116 B may be used to upload or down load audio, video and other image data to and from the device  100 . For example, the data port  116 B may be used to download songs and play lists, audio books, ebooks, photos, and the like into the storage mechanism of the computing device  100 . The power port  116 C, on the other hand, allows power to be delivered to the computing device  100 . In some cases, the data port  116 B may serve as both a data and power port thus replacing a dedicated power port  116 C. A data port such as this is described in greater detail in pending U.S. Pat. App. Ser. No.: 10/423,490, which is herein incorporated by reference. 
       FIGS. 3A and 3B  are diagrams of a hand held computing device  150 , in accordance with one embodiment of the present invention.  FIG. 3A  is perspective diagram showing the computing device  150  in its assembled form, while  FIG. 3B  is an exploded perspective diagram showing the computing device  150  in its unassembled form. The computing device  150  may generally correspond to the computing device  100  shown and described in  FIG. 2 . 
     The computing device  150  includes a housing  152 , which serves to support the internal components of the computing device  150  in their assembled position within the device  150 . The housing  152  includes several components including a seamless enclosure  154 , a bottom end cap  156  and a top end cap  158 . The seamless enclosure  154  extends along a longitudinal axis  160 , and includes an internal lumen  162  which is sized and dimension for receipt of the internal components of the computing device  150  through a first open end  164  and a second open end  166  opposite the first open end  164 . The end caps  156  and  158  cover the open ends  164  and  166  of the seamless enclosure  154  in order to provide a fully contained housing  152 . Although the end caps  156  and  158  can be applied in a variety or ways, in this particular embodiment, each of the end caps  156  and  158  includes a shape that coincides with the internal shape of the seamless enclosure  154  such that they may be inserted into the open ends, i.e., the outer periphery of the end caps  156 ,  158  matches the inner periphery of the lumen  162 . Furthermore, the end caps  156  and  158  are positioned to be flush with the bottom  170  and top surfaces  172  of the seamless enclosure  154  thereby forming a housing  152  with a substantially uniform appearance. 
     In order to help guide at least a portion of the internal components to their desired position within the seamless enclosure  154 , the seamless enclosure  154  includes an internal rail system  176  including a pair of rails  177  that protrude out the inner sides of the seamless enclosure  154 . The two rails  177 , which are similarly shaped, are placed in an opposed relationship directly across from one another. The rails  177  provide reference surfaces for receiving and supporting some portion of the internal components. The portion of the internal components that engages the rails  177  is typically an edge of the internal components. The internal rail system  176  is integrally formed with the seamless enclosure  154 . By integral, it is meant that the seamless enclosure  154  and the rail system  176  are formed from a single piece of material. 
     In fact, the seamless enclosure  154  along with integrally formed internal rails  176  are preferably formed from an extrusion process. The extrusion process produces the desired cross section in a continuous tube, which can be cut to form a seamless enclosure  154  including the internal rails  176  with a desired length. That is, the seamless enclosure  154  including the internal rails  176  is formed from an elongated continuous extruded tube that has been cut to a desired length. As should be appreciated, the features of the internal rail  176  are extruded along with the seamless enclosure  154  thereby forming rails that have the same length as the seamless enclosure, i.e., the extrusion process produces rails that extend from the top to the bottom end of the seamless enclosure. 
     Although the extrusion process allows for a variety of materials, in this particular embodiment, the continuous tube is formed from a metal material and more particularly from aluminum (or some other material that has similar properties to aluminum). The end caps  156  and  158 , on the other hand, are formed from a plastic material such as ABS using a manufacturing process such as injection molding. 
     Moving along, the internal components of the computing device  150  include a printed circuit board  180  that contains various integrated circuit chips and other circuitry that provide computing operations for the computing device  150 . The printed circuit board  180  may for example include a microprocessor  182 , memory  184 , a data port  186 , and a switch  188 . Although not shown, the printed circuit board  180  may also contain interconnecting circuitry and related components that help to operatively couple the various internal components together. In order to provide access to some of these components, the top end cap  158  includes an opening  189 A for the switch  188  and the bottom end cap  156  includes an opening  189 B for the data port  186 . As shown, the switch  188  may include a switch cap  191  that is snapped onto the switch  188  after the top end cap  158  is finally assembled. 
     The internal components of the computing device  150  also include a display  190  such as for example a liquid crystal display. The liquid crystal display  190  is mounted on the front of the printed circuit board  180 . The LCD  190  may be mounted to the PCB  180  using a variety of techniques. By way of example, the LCD  190  may include locking tabs that snap onto the printed circuit board  180  in order to secure the LCD  190  thereto. Alternatively, the LCD  190  may be a stand alone assembly, i.e., floating rather than mounted to the PCB  180 . In either case, the LCD  190  is operatively coupled to the printed circuit board  180  and its various components. This may for example be accomplished through a flex circuit connector that couples to a connector located on the printed circuit board  180 . 
     In order to provide visible access to the display  190 , the seamless enclosure  154  includes an access opening  192  having a shape that coincides with the shape of the viewing area of the LCD  190 . The access opening  192  may be formed by processes such as machining, drilling, cutting, punching and/or the like. In most cases, a clear window  194  (typically formed from plastic) is positioned in the access opening  192  in front of the LCD  190  in order to protect the LCD  190  from damage. In fact, when assembled, the window  194  may be considered a portion of the housing  152 . The window  194  may be attached to the seamless enclosure  154  using a variety of techniques including but not limited to fasteners, snaps, adhesives, etc. In the illustrated embodiment, the window  194  includes a raised section  196  that sits in the opening  192  and that is either substantially flush or recessed with the outer surface of the seamless enclosure  154  so that it does not protrude above the outer surface and a flange section  198  having an adhesive layer that secures the window  194  to the inner surface of the seamless enclosure  154 . By having the window flush or recessed, scratching of the window is substantially avoided. 
     The internal components of the computing device  150  also include a hard drive  200 . The hard drive  200 , which is located at the rear of the printed circuit board  180 , is operatively coupled to the printed circuit board  180  and its various components. This may for example be accomplished through a flex circuit connector that couples to a connector located on the printed circuit board  180 . The hard drive  200  may be mounted (as shown) or it may be free floating relative to the PCB  180 . Although not a requirement, the hard drive  200  may be surrounded by a plurality of bumpers  202  that serve to protect the hard drive  200  when assembled, i.e., the bumpers  202  help to prevent shocks to the hard drive  200 . They also may provide a surface that helps retain the hard drive  200  within the housing  152  (e.g., friction, compliance, etc.). As should be appreciated, the hard drive gives the device massive storage capacity unlike flash based devices. By way of example, the hard drive may have capacities of 5 GB, 10 GB, 15 GB, 20 GB and so on. To cite an example, when the device is used as a music player, a 20 GB hard drive can store up to 4000 songs or about 266 hours of music. 
     The internal components of the computing device  150  also include a battery  206 . The battery  206 , which is located at the rear of the printed circuit board  180 , is operatively coupled to the printed circuit board  180  and its various components. This may for example be accomplished through a connector that couples to a connector located on the printed circuit board  180 . In some cases, the battery may be attached to the backside of the PCB using for example an adhesive such as double sided tape. In other cases, the battery  206  may be free floating. By way of example, the battery may correspond to a rechargeable lithium polymer battery or a lithium ion prismatic cell. These types of batteries are capable of offering about 10 hours of continuous playtime to the device  150 . 
     The internal components of the computing device  150  also include an audio subassembly  210 . The audio subassembly  210 , which is located at the top of the printed circuit board  180 , is operatively coupled to the printed circuit board  180  and its various components. The audio subassembly  210  includes at least a small printed circuit board  212  and an audio jack  214 . The audio subassembly may also contain various circuit components and interconnecting circuitry, which are attached to the PCB  212 . Although the audio subassembly may be free floating, in the illustrated embodiment, the audio subassembly  210  is mechanically coupled to the PCB  180  so that the PCB  180  and audio subassembly  210  operate as a single unit (i.e., form a single structure). By way of example, they may be coupled together using fasteners, adhesives or snaps. 
     In one particular embodiment, the audio subassembly  210  is both operatively and mechanically coupled to the main printed circuit board  180  and its various components through a connector, which is located on the audio printed circuit board  212 , and which couples to a connector located on the main printed circuit board  180 . The coupling between the connectors may include a friction element or mechanical detent that substantially secures the audio subassembly  210  to the printed circuit board  180 . In order to provide access to the audio jack  214  audio subassembly  210 , the top end cap  158  includes an opening  193  having a shape that coincides with the shape of the audio jack  214 . In most cases, the housing of the audio jack  214  is substantially flush with the outer surface of the top end cap  158 . 
     During assembly and referring to the top end of the seamless enclosure  154 , the integrated system comprising, the PCB  180 , LCD  190 , hard drive  200 , battery  206  and audio subassembly  210  is inserted into the lumen  156  of the seamless enclosure  154  as a single unit. The printed circuit board  180  essentially acts as a carrier for placing these components inside the housing  152 . During assembly, the PCB  180  is inserted in the direction of the y axis into the space provided by a portion of the side and bottom surfaces of the seamless enclosure  154  as well as the bottom surface of the internal rail system  176 . This space may be referred to as a channel. During insertion, a top surface of the PCB  180  slides along the bottom surface of the internal rail system  176  within the space. As should be appreciated, the side walls, bottom surface and rails help constrain the PCB  180  within the housing  152  during and after insertion. The PCB  180  is typically slid into the seamless enclosure  154  to a depth (y) that places the LCD  190  directly behind the access opening  192 . Furthermore, the internal rail system  176  helps locate the PCB  180  and thus the LCD  190  in the direction of the z axis while the side walls of the seamless enclosure  154  help locate the PCB  180  and thus the LCD  190  in the direction of the x axis. 
     In order to ensure proper positioning as well as to help secure the integrated system in place, a top plate  218  may be provided that prevents further sliding and sets the final position of the integrated system. The top plate  218  may be attached to the main PCB  180  or the PCB  212  of the audio subassembly  210 . The top plate  218  may be attached using a variety of techniques including but not limited to fasteners, adhesives, snaps and/or the like. In the illustrated embodiment, the top plate  218  is attached to the PCB  212  of the audio subassembly  210 . When the integrated system is slid into the lumen  162 , the bottom surface of the top plate  218  abuts a recessed area  220  formed in the top surface of the seamless enclosure  154 . The recessed area  220  may for example be formed by machining a portion of the top surface of the seamless enclosure  154  (including the rails  177 ). Once positioned against the recessed area  220 , the top plate  218  is attached to the seamless enclosure  154  using fasteners such as screws  219 . 
     The depth of the top plate  218  generally depends on the desired position of the top end cap  158 . In order to produce a flush top surface, the top plate  218  is typically positioned to a depth corresponding to the thickness of the top plate  218  and the top end cap  158 . Once the top plate  218  is secured, the top end cap  158  may be attached thereto. The top end cap  158  may be attached to the top plate  218  using fasteners, snaps, adhesives, and/or the like. In order to make assembly easier and to prevent the undesirable look of fasteners, the top plate  218  may include several retaining features for receiving tabs located on the inside surface of the top end cap  158 . When the top end cap  158  engages the top plate  218 , the tabs are inserted into the retaining features thereby securing the top end cap  158  to the top plate  218  (via a snapping action). 
     In one embodiment, the audio subassembly  210  includes a positioning adjustment portion (not shown) configured to provide position relief when attaching the top plate  218  to the seamless enclosure  154 . That is, the adjustment portion allows some degree of tolerance or play so that the top plate  218 , which is connected to the integrated system via the audio subassembly  210 , can be precisely placed relative to the seamless enclosure  154 . The adjustment portion may be separate component or be integrally formed with the PCB  212 . When separate, the adjustment portion may be or include a compliant member, a flexure, a mechanical mechanism and/or the like. When integral, the adjustment portion may be a flexure formed from the PCB  212 . In particular, the adjustment portion may be a tab that has been partially cut away from the PCB  212  thereby enabling it to flex or bend. 
     The internal components of the computing device  150  also include an input assembly  230 . The input assembly  230  may be widely varied. The input assembly generally depends on the type of device. In the illustrated embodiment, the input assembly  230  includes a touch pad  232  and a center switch  234  positioned on a frame  236 . The switch  234  is a portion of a button, which may be actuated by a user to perform actions in the device  150 . Although the input device  230  is structurally separated from the printed circuit board  180 , it is operatively coupled to the printed circuit board  180  and its various components. This may be accomplished for example through a flex circuit connector that couples to a connector located on the printed circuit board  180 . This connection is typically made after the PCB  180  and input device  230  have been inserted into the seamless enclosure  154 . 
     In some cases, the touch pad  232  is capable of moving relative to the frame  236  in order to actuate additional mechanical switches housed within the frame  236 . Each of the switches represents a button, which may be actuated by a user. By way of example, the input assembly  230  may correspond to any of those input devices disclosed in U.S. Pat. App. Ser. No.: 10/643,256, which is herein incorporated by reference. 
     In order to provide user access to the input assembly  230 , the seamless enclosure  154  includes an access opening  237  having a shape that coincides with the shape of the touch pad  232 . Like the first access opening  192 , the second access opening  237  may be formed from processes (individually or in combination) such as machining, drilling, cutting, punching and/or the like. In most cases, a button cap  238  and cover  239  is positioned in the access opening  237  in front of the touch pad  232  and switch  234  in order to seal the device  150  and protect the touch pad  232  and switch  234  from damage. The cover  239  is generally sized for placement in the access opening  237  and to provide a surface that is substantially flush with the outer surface of the seamless enclosure  154 . The cover  239  is typically attached to the touch pad  232  using an adhesive. The button cap  238  typically includes a flange potion that is trapped between the cover  239  and the input assembly  230  thereby securing the button cap  238  to the input assembly  230 . 
     During assembly and referring to the bottom end of the seamless enclosure  154 , the input assembly  230  is inserted into the lumen  156  of the seamless enclosure  154 . The frame  236  acts as a carrier for placing the input assembly  230  inside the housing  152 . During assembly, the input assembly  230  is inserted in the direction of the y axis into the space provided by a portion of the side and top surfaces of the seamless enclosure  154  as well as the top surface of the internal rail system  176 . This space may be referred to as a channel. During insertion, a bottom surface of the frame  236  slides along the top surface of the internal rail system  176  within the space. As should be appreciated, the side walls, top surface and rails help constrain the input assembly  230  within the housing  152  during and after insertion. The input assembly  230  is typically slid into the seamless enclosure  154  to a depth (y) that places the touch pad  232  directly behind the access opening  237 . The depth may be set by posts located inside the seamless enclosure. In the illustrated embodiment, the window  194  includes a pair of abutment stops  240  that prevents further sliding and sets the final position of the input assembly  230  in the y direction. Furthermore, the internal rail system  176  helps locate the touch pad  232  and switch  234  in the direction of the z axis while the side walls of the seamless enclosure  154  help locate the touch pad  232  and switch  234  in the direction of the x axis. 
     In order to ensure proper positioning as well as to help secure the input assembly  230  in place, the input assembly  230  may include a locking feature that locks the input assembly  230  in place when the input assembly  230  is finally inserted into the seamless enclosure. In one embodiment, the locking feature is in the form of a tab  242  that snaps into a recess located on the inner surface of the seamless enclosure  154 . The recess may be formed by machining a groove in the inner surface of the seamless enclosure  154  at a position that coincides with the input assembly  230  when it is finally inserted. 
     Like the top end, the bottom end may include a structural plate, i.e., bottom plate  244 . The bottom plate  244  is configured to act as a reference support surface for the bottom end cap  156 . It may also act as a reference surface for the input assembly  230  or the main system assembly. The bottom plate  244  may be connected to the seamless enclosure  154  and/or the input assembly  230 . The bottom plate  244  may be attached using a variety of techniques including but not limited to fasteners, adhesives, snaps and/or the like. By way of example, the bottom plate  244  may be connected in a manner similar to the top plate (attached to the input assembly and inserted into a recess). 
     Alternatively, as shown in the Figure, the bottom plate  244  may include retaining features  246  that snap into recesses formed in the inner surface of the seamless enclosure  154  thereby mechanically securing the bottom plate  244  to the seamless enclosure  154 . The recesses may be formed by machining grooves in the inner surface of the seamless enclosure  154  at a position that coincides with the retaining features  246  when the bottom plate  244  is inserted in the seamless enclosure  154 . During assembly, the retaining features  246  are flexed inwardly, and the bottom plate  244  is placed inside the seamless enclosure  154 . Once the bottom plate  244  is correctly positioned next to the recesses, the retaining features  246  are unflexed outwardly thereby causing them to be outwardly extended into the recesses, i.e., the retaining features  246  are received by the recesses. A tool may be required to flex the retaining features in a manner analogous to retaining rings. Unlike retaining rings, however, the bottom plate is not circular, and spans the inside of the enclosure to support internal and external parts. Furthermore, the bottom plate is fixed in place and cannot rotate as circular retaining rings thus providing a reference surface in more than just the y direction, i.e., the bottom plate provides a reference surface in the x, y and z directions. This enables the bottom plate to fixedly support the end cap. 
     The depth of the bottom plate  244  generally depends on the desired position of the bottom end cap  156 . In order to produce a flush bottom surface, the bottom plate  244  is typically positioned to a depth corresponding to the thickness of the bottom plate  244  and the bottom end cap  156 . Once the bottom plate  244  is secured, the bottom end cap  156  may be attached thereto. The bottom end cap  156  may be attached to the bottom plate using fasteners, snaps, adhesives, and/or the like. In order to make assembly easier and to prevent the undesirable look of fasteners, the bottom plate  244  may include several retaining features for receiving tabs located on the inside surface of the bottom end cap  156 . When the bottom end cap  156  engages the bottom plate  244 , the tabs are inserted into the retaining features thereby securing the bottom end cap  156  to the bottom plate (via a snapping action). 
     The bottom plate may be formed from a variety of materials such as metals and plastics. The material that is selected typically offers a balance between resistance to deformation so as to provide a structural surface and bendability so that the flexure arms can be flexed during installation. In the illustrated embodiment, the bottom plate is formed from stainless steel, and more particularly high hardness stainless steel. 
       FIG. 4 , which is top view, in cross section of the assembled device  150 , shows the position of the various components of the integrated system inside the housing  152  and more particularly the seamless enclosure  154 . As shown, the top surface at the edge of the printed circuit board  180  abuts the bottom surface of the rails  177 . Furthermore, the battery  206  and hard drive  200  are contained within the lower channel formed by the rails, sides and back surface of the seamless enclosure  154 . In most cases, there is a snug fit between these components and the surrounding portions of the seamless enclosure  154  so as to help hold the integrated system in place. Moreover, the LCD  190  protrudes above the rails  177  through a gap formed between the rails  177  so that it is positioned directly underneath the window  194 . In some cases, the gap may be dimensioned to form a snug fit between the LCD and rails to better align the LCD with the opening, i.e., the rails provide a reference surface for the LCD in the x direction. 
       FIG. 5 , which is bottom view, in cross section of the assembled device  150 , shows the position of the input assembly  230  inside the housing  152 , and more particularly the seamless enclosure  154 . As shown, the bottom surface at the edge of the frame  236  abuts the top surface of the rails  177 . Furthermore, most of the input assembly  230  is contained within the upper channel formed by the rails, sides and surface of the seamless enclosure  154 . In most cases, the input assembly  230  is sized and dimensioned to fit snuggly inside the upper channel. A small portion of the frame (or other component of the input assembly  230 ) may be positioned within the gap formed between the two rails  177 . 
       FIGS. 6A-6C  show the insertion and mounting of the input assembly  230  inside the seamless enclosure  154 . As shown in  FIGS. 6A and 6B , the input assembly  230  is inserted into the bottom end of the seamless enclosure  154 . In particular, the front edge of the input assembly  230  is placed within the upper channel against the rails  177 , and the input assembly  230  is slid along the rails  177  into the seamless enclosure  154 . As shown in  FIG. 6C , when the input assembly  230  nears its final position in the y direction, the tab  242  on the rear of the input assembly  230  snaps into a recess  256  located on the inner top surface of the seamless enclosure  154  thereby securing the input assembly  230  between this point and the abutment stops  240  located on the window  194 . The positions of the abutment stop  240  and recess  256  are preferably positioned such that the tab  242  engages the recess  256  as the input assembly  230  presses against the abutment stop  240 . This particular arrangement helps prevent any subsequent movement of the input assembly  230 , i.e., locks it into place (in the y direction). 
       FIGS. 7A and 7B  show the bottom plate  244  in its unassembled and assembled positions. The bottom plate  244  includes a body  261  and a plurality of flexure arms  246 . The body  261  is typically configured to fill the available space between the opposing sets of retaining arms  256  so as to produce a more rigid structure for supporting the various components enclosed within or attached to the enclosure  154 . The flexure arms  246 , which extend from the body  261 , are configured to bend in towards the body  261  when a force F is applied to the flexure arms  246 . In some cases, the interface between the body and the flexure arms includes a radius. The radius may be adjusted to tune the stiffness of the flexure arms. The force F may for example be provided by a pinching tool that engages holes  262  located in each of the flexure arms  246 . 
     Both the body and the arms are configured to cooperate to form the shape of the bottom plate. The shape may be widely varied although the shape is generally configured to be non circular so as to provide a better reference surface (e.g., substantially rectangular). In fact, the shape may coincide with the shape of the lumen found in the enclosure. 
     The bottom plate  244  may be formed from a variety of structural materials including metals and plastics. By way of example, the bottom plate  244  may be formed from stamping a sheet of metal (e.g., steel) or from molding a piece of plastic. 
     As shown in  FIG. 7B , the bottom plate  244  is positioned inside the lumen  162  of the seamless enclosure  154 . In particular, the flexure arms  246  are retained within slots  263  located on the inside surface of the seamless enclosure  154 . In fact, the flexure arms may include outward protrusions that provide a better interface between the flexure arms and the slots. The bottom plate  244 , which is designed to receive the bottom end cap  156 , is positioned at the end of the seamless enclosure  154  so as to produce a reference support surface for the bottom end cap  156 . In essence, the bottom plate  244  when retained acts as an extension of the seamless enclosure  154 . The depth of the bottom plate  244  is typically configured to place the outer surface of the bottom end cap  244  substantially flush with the bottom surface  264  of the seamless enclosure  154 . The bottom plate  244  may include various features  266  for receiving locking tabs located on the bottom end cap  156 . As should be appreciated, the features may be openings or voids that receive snaps on the bottom of the end cap, i.e., the snaps snap into the openings thereby securing the bottom end cap to the bottom plate. The bottom plate  244  may also include an opening  267 , which provides a clearance for the connector  186 . 
       FIG. 8  is a diagram of the audio subassembly  210 , in accordance with one embodiment of the present invention. As shown in  FIG. 8A , the PCB  212  is divided into a flexure portion  270 , a first base portion  272  and a second base portion  274 . This may be accomplished by cutting a groove in the PCB  212 . The audio jack  214  is attached to the first base portion  272  and the top plate  218  is attached to the audio jack  214 . The second base portion  274  includes a connector  276  that mates with a connector on the main PCB  180  in order to operatively and mechanically couple the audio subassembly  210  to the main PCB  180 , i.e., form a single unit. The flexure portion  270  is positioned between the first and second base portions  272  and  274 . The flexure portion  270  allows the first base portion  272  to move relative to the second base portion  274 . The flexure  270  causes the first base portion  272  and thus the top plate  218  to float relative to the main PCB  180  while still being constrained thereto. As shown in  FIGS. 8B and 8C , the flexure portion  270  is capable of flexing or bending so that the first base portion  272  can shift relative to the second base portion  274  thereby allowing the top plate  218  to be correctly aligned with the recess  220  of the seamless enclosure  154 . That is, the flexure  270  allows the top plate  218  to shift into mating engagement with the recess  220  of the seamless enclosure  154  thereby producing a tight fit between the top plate  218  and the seamless enclosure  154 . 
       FIGS. 9A-9H  are various diagrams of the seamless enclosure  154 . As shown, the seamless enclosure  154  includes a planar front surface  280 , a back planar surface  282  and rounded sides  284 . The access openings  192  and  237  for the LCD  190  and input assembly  230  are located in the front planar surface  280 . The seamless enclosure  154  also includes a lumen  162  therethrough that defines openings at each of the ends of the seamless enclosure  154 . The rails  177 , which extend substantially through the lumen  162 , are located in an opposed relationship inside the lumen  162 . The rails  177  protrude away from the sides of the lumen  162  and are positioned closer to the front planar surface  280  than the back planar surface  282 . The end at the top of the seamless enclosure  154  includes a recess  220  for receiving the top plate  218  and top end cap  158 . The recess  220  essentially forms a lip to which the top plate  218  is secured. The end at the bottom of the seamless enclosure  154  includes a cut out section  290  for receiving the bottom plate  244  and the bottom end cap  156 . The cut out  290  is formed by shortening the ends of the rails  177 . This end also includes a plurality of slots  263  for receiving the flexure arms  246  of the bottom plate  244 . 
       FIG. 10  is a method of manufacturing an electronic device  340 , in accordance with one embodiment of the present invention. The electronic device may generally correspond to any of those previously described. The method generally includes several operations including: the formation of the housing  342 , the assembly of the internal components including the main system assembly  244  and the touch pad assembly  346 , and the final assembly of the housing  348 . 
     Referring first to the formation of the housing  342 , the operation starts with block  352  where a tube having internal rails is extruded. Following block  352 , the operation proceeds to block  354  where the extruded tube is cut to a desired length. Following block  354 , the operation proceeds to block  356  where the access openings are formed in the extruded tube. By way of example, the access opening may be associated with a user interface of the electronic device. Following block  356 , the operation proceeds to block  358  where a recess is formed into a top surface of the extruded tube. Following block  358 , the operation proceeds to block  360  where one or more threads are formed in the recess at the top surface of the extruded tube. Following block  360 , the operation proceeds to block  362  where a portion of the internal rails are removed from the bottom surface of the extruded tube. Following block  362 , the operation proceeds to block  364  where slots are formed in the area where the internal rails were removed. 
     Referring to the assembly of the various components inside the tube  344 , the operation starts with block  366  where a window is mounted in one of the access openings. This may for example be accomplished using an adhesive such as glue or tape. Following block  366 , the operation proceeds to block  368  where a main system assembly is inserted into the top end of the extruded tube along the lower surface of the internal rails. The main system assembly is typically sized and dimensioned for sliding receipt between the lower surface of the internal rails and the side and back surface of the extruded tube. The main system assembly generally includes a printed circuit board, which acts as the carrier for several components including: system electronics (e.g., microprocessor and memory); an LCD; a battery; I/O assemblies (audio assembly, data port assembly); etc. Following block  368 , the operation proceeds to block  370  where the main system assembly is mounted to the extruded tube. This is generally accomplished through a top plate that is attached to the main system assembly. When the main system assembly is finally inserted into the extruded tube, the top plate presses against the upper surface of the recess thereby setting the position of the main system assembly in its desired position along the longitudinal axis of the extruded tube. The top plate is then attached to the extruded tube via screws and the previously formed threads. 
     Referring to the assembly of the touch pad assembly  346 , the operation starts with block  372  where the touch pad assembly is inserted into the bottom end of the extruded tube along the upper surface of the internal rails. The touch pad assembly is typically sized and dimensioned for sliding receipt between the upper surface of the rail and the side and front wall of the extruded tube. When the touch pad assembly is finally inserted into the extruded tube, the top surface of the touch pad assembly presses against a pair of abutment stops located at the bottom end of the window thereby setting the position of the touch pad assembly in its desired position along the longitudinal axis of the extruded tube. In particular, the touch pad of the touch pad assembly is positioned directly behind the second access opening. 
     Following block  372 , the method proceeds to block  374  where the touch pad assembly is operatively coupled to the main system assembly. By way of example, a simple connector connection may be made or a solder connection can be made. In the illustrated embodiment, the touch pad assembly includes a flex connector that couples to a connector located on the PCB. Following block  374 , the operation proceeds to block  376  where a button cap and label is situated over the touch pad of the touch pad assembly. The button cap is disposed over a center switch and the label is disposed over an edge of the button cap as well as the touch pad. The label is typically attached to the touch pad using an adhesive. In most cases, the label is positioned in the recessed area formed by the touch pad and the edge of the access opening. The label therefore helps to secure the touch pad assembly in its desired position within the extruded tube. Although not a requirement, the top surface of the label is typically positioned substantially flush with the outer surface of the extrude tube. 
     Referring to the final assembly of the device, the operation starts with block  378  where the snap plate is inserted into the slotted bottom end of the extruded tube thereby securing the snap plate to the extruded tube. Following block  378 , the operation proceeds to block  380  where the bottom end cap is mounted to the bottom end of the extruded tube. This is generally accomplished by positioning the bottom end cap in the recessed area formed by the snap plate and the inner surface of the extruded tube, and snapping tabs located on the bottom end cap into the snap plate thereby securing the bottom end cap to the snap plate. In most cases, the outer surface of the bottom end cap is made flush with the bottom surface of the extruded tube. Following block  380 , the operation proceeds to block  382  where the top end cap is mounted to the top end of the extruded tube. This is generally accomplished by positioning the top end cap in the recessed area formed by the top plate and the inner surface of the extruded tube, and snapping tabs located on the top end cap into the top plate thereby securing the top end cap to the top plate. It should be pointed out that during insertion of the top end cap into the recessed area, a protruding member of the audio assembly is inserted through an opening in the top end cap. Because the audio assembly includes a flexure, the protruding member has a small amount of tolerance or play that allows for easy placement through the opening. Once the top end cap is attached, the switch cap may be placed on the switch assembly through another opening in the top end cap. 
     While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents, which fall within the scope of this invention. For example, although the invention is primarily directed at an integrally formed internal rail system, in some cases the internal rail system may be a separate component that is attached within the main body. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention. For example, although an extrusion process is preferred method of manufacturing the integral tube, it should be noted that this is not a limitation and that other manufacturing methods may be used (e.g., injection molding). It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.