Patent Publication Number: US-8995677-B2

Title: Accessory controller for electronic devices

Description:
BACKGROUND 
     This invention relates to electronic devices, and more particularly, to accessories for electronic devices such as accessories with button controllers. 
     Electronic devices such as computers, media players, and cellular telephones typically contain audio jacks. Accessories such as headsets have mating plugs. A user who desires to use a headset with an electronic device may connect the headset to the electronic device by inserting the headset plug into the mating audio jack on the electronic device. Miniature size (3.5 mm) phone jacks and plugs are commonly used with electronic devices such as notebook computers and media players, because audio connectors such as these are relatively compact. 
     Stereo audio connectors typically have three contacts. The outermost end of an audio plug is typically referred to as the tip. The innermost portion of the plug is typically referred to as the sleeve. A ring contact lies between the tip and the sleeve. When using this terminology, stereo audio connectors such as these are sometimes referred to as tip-ring-sleeve (TRS) connectors. The sleeve can serve as ground. The tip contact can be used in conjunction with the sleeve to handle a left audio channel and the ring contact can be used in conjunction with the sleeve to handle the right channel of audio. 
     In devices such as cellular telephones, it is often necessary to convey microphone signals from the headset to the cellular telephone. In arrangements in which it is desired to handle both stereo audio signals and microphone signals, an audio connector typically contains an additional ring terminal. Audio connectors such as these have a tip, two rings, and a sleeve and are therefore sometimes referred to as four-contact connectors or tip-ring-ring-sleeve (TRRS) connectors. When a four-contact connector is used, the sleeve may serve as ground. The tip contact and the outermost ring contact may be used in conjunction with the ground to carry audio for the left and right headset speaker audio channels. The innermost ring contact may be used in conjunction with the ground to carry microphone signals. 
     Some users may wish to operate their cellular telephones or other electronic devices remotely. To accommodate this need, some modern microphone-enabled headsets feature a button. When the button is pressed by the user, the microphone line is shorted to ground. Monitoring circuitry in a cellular telephone to which the headset is connected can detect the momentary grounding of the microphone line and can take appropriate action. In a typical scenario, a button press might be used to answer an incoming telephone call or might be used skip tracks during playback of a media file. 
     Conventional button arrangements such as these offer limited functionality. 
     It would therefore be desirable to be able to provide headsets and other accessories with improved button arrangements. 
     SUMMARY 
     Accessories such as headsets are provided that include button controller assemblies. The headsets may each include speakers, a button controller assembly, an audio plug, and wires that interconnect the speakers, button controller assembly, and the audio plug. The button controller assemblies may each be formed from a housing having first and second housing portions. 
     The first and second housing portions of each button controller assembly may have associated plastic engagement features. For example, the first housing portion may have snaps. A plastic frame may be ultrasonically welded to the second housing portion. When assembled to form a finished unit, the snaps on the first housing may engage rails on the frame. Sufficient clearance may be provided between respective engagement structures to allow the first and second housing portions to float with respect to each other. The first and second housing portions may move unimpeded by the engagement structures up to a given amount of travel. When the given amount of travel is reached, the first housing structure may still flex. This allows the first housing structures to bend inwardly towards the second housing structure and its associated frame when the first and second housing structures are squeezed together by a user to actuate a desired button within the button controller assembly. 
     Button functionality may be provided by dome switches mounted within the button controller assembly. The housing portions may be formed using a two-shot molding process so that each housing portion may include two different types of plastic. The plastics may have different colors, different textures, different rigidities, or other suitable properties. By using different colors for different regions of the housing, certain portions of the housing may be concealed from view and button regions may be marked. 
     Elastomeric members within the button controller assembly may be used to help bias the housing portions apart. The elastomeric members may be mounted to opposing ends of the plastic frame. Wires for the headset may be engaged by holes in the plastic frame and crimped metal bands. 
     Integrated circuits, a microphone, and other circuitry may be mounted within the button controller assembly. The circuitry may be used to detect button actuation events when a user squeezes various portions of the housing together. When a button selection is detected, the circuitry may transmit corresponding signals to the electronic device over the wires of the headset. 
     Air gaps may be formed at the interfaces between plastic portions in the button controller assembly. For example, a thin slit may be formed where the first and second housing portions meet. Slit-shaped air gaps may also be formed at the intersection between the housing portions and the plastic frame. Because of the presence of these air gaps, sound may reach the microphone in the interior of the button controller assembly without use of a dedicated microphone port. 
     To help a user determine whether or not the button controller assembly contains a microphone, the outer surface of the button controller assembly housing may be provided with a visual indicator that the button controller assembly contains a microphone. The visual indicator may, as an example, be provided in the form of a nonoperational microphone port. The nonoperational microphone port may have structures that resemble a traditional microphone port such as a metal member with holes. The nonoperational port may be formed by omitting holes through the housing, thereby blocking sound from entering the interior of the housing through the port. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of illustrative accessories in communication with an electronic device in a system in accordance with an embodiment of the present invention. 
         FIG. 2  is a perspective view of an illustrative accessory such as a headset that may be provided with user-selectable buttons in accordance with an embodiment of the present invention. 
         FIG. 3  is a perspective view of an illustrative accessory such as a headset that has been connected to an adapter accessory having user-selectable buttons in accordance with an embodiment of the present invention. 
         FIG. 4  is a perspective view showing the upper surface of an illustrative button controller assembly for controlling operation of an electronic device in accordance with an embodiment of the present invention. 
         FIG. 5  is a perspective view showing the lower surface of an illustrative button controller assembly for controlling operation of an electronic device in accordance with an embodiment of the present invention. 
         FIG. 6  is an exploded perspective view of an illustrative button controller assembly for controlling operation of an electronic device in accordance with an embodiment of the present invention. 
         FIG. 7  is a cross-sectional side view of an illustrative button controller assembly for controlling operation of an electronic device in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates generally to electronic devices and accessories for electronic devices. 
     A typical accessory may be, for example, a headset that includes a button controller assembly. The button controller assembly may include buttons for controlling operation of the electronic device. 
     An illustrative system in which an accessory may be used with an electronic device is shown in  FIG. 1 . As shown in  FIG. 1 , electronic device  12  may be coupled to accessory  14  via communications path  16 . 
     Electronic device  12  may be, for example, a device such as a desktop computer or a portable electronic device such as a laptop computer or a small portable computer of the type that is sometimes referred to as an ultraportable. Electronic device  12  may also be a somewhat smaller portable electronic device such as a wrist-watch device, pendant device, or other wearable or miniature device. If desired, electronic device  12  may include wireless capabilities. 
     Electronic device  12  may be a handheld electronic device such as a cellular telephone, a media player with wireless communications capabilities, a handheld computer (i.e., a personal digital assistant), a remote controller, global positioning system (GPS) devices, a handheld gaming device, etc. Electronic device  12  may also be a hybrid device that combines the functionality of multiple conventional devices. Examples of hybrid electronic devices include a cellular telephone that includes media player functionality, a gaming device that includes a wireless communications capability, a cellular telephone that includes game and email functions, and a portable device that receives email, supports mobile telephone calls, has music player functionality and supports web browsing. Electronic device  12  may also be equipment such as a television or audio receiver, or other suitable electronic equipment. Electronic device  12  may be provided in the form of stand-alone equipment (e.g., a handheld device that is carried in the pocket of a user) or may be provided as an embedded system. Examples of systems in which device  12  may be embedded include automobiles, boats, airplanes, homes, security systems, media distribution systems for commercial and home applications, display equipment (e.g., computer monitors and televisions), etc. These are merely illustrative examples. 
     Path  16  may include conductive lines (wires) for connecting accessory  14  to electronic device  12 . There may be, for example, four conductive lines in path  16  or more lines or fewer lines may be used. 
     A headset typically includes a pair of speakers that a user can use to play audio from the electronic device. Accessory  14  may be a headset that has a button controller assembly with one or more buttons. When a user actuates buttons on the button controller assembly, circuitry in the button controller assembly may gather button actuation data and may transmit the button actuation data to electronic device  12  over path  16 . 
     As an example, when the user presses a button on the button controller assembly in the accessory, a corresponding signal may be provided to the electronic device to direct the electronic device to take an appropriate action. Because the button is located on the headset rather than on the electronic device, a user may place the electronic device at a remote location such as on a table or in a pocket, while controlling the device using conveniently located headset buttons. 
     If the electronic device is a media player and is in the process of playing a song or other media file for the user, the electronic device may be directed to pause the currently playing media file when the user presses a button. As another example, if the electronic device is a cellular telephone with media player capabilities and the user is listening to a song when an incoming telephone call is received, actuation of the button by the user may direct the electronic device to answer the incoming telephone call. Actions such as these may be taken, for example, while the media player or cellular telephone is stowed within a user&#39;s pocket. 
     If desired, an accessory with a button controller assembly may be provided in the form of an adapter. As shown in  FIG. 1 , for example, accessory  14  may be an adapter that provides a user with button control functionality. A conventional stereo headset or other suitable accessory  130  (e.g., an accessory without button functionality or with reduced button functionality relative to accessory  14 ) may, in turn, be plugged into accessory  14  using communications path  17 . Path  17  may be, for example, a three-wire or four-wire path (as examples). 
     For clarity, aspects of the present invention are sometimes described in the context of accessories such as headsets. This is, however, merely illustrative. The accessories in system  10  may take the form of any suitable equipment that is connected to electronic device  12 . Examples of accessories include audio devices such as audio devices that contain or work with one or more speakers. Speakers in accessory  14  may be provided as an earphone or a headset or may be provided as a set of stand-alone powered or unpowered speakers (e.g., desktop speakers). An accessory may, if desired, include audio-visual equipment such as a receiver, amplifier, television or other display, etc. Devices such as these may use paths such as path  16  to receive audio signals from device  12 . The audio signals may, for example, be provided in the form of analog audio signals that need only be amplified or passed to speakers to be heard by the user of device  12 . An optional microphone in the accessory may pass microphone signals to device  12 . Buttons or other user interface devices may be used to gather user input for device  12 . The use of these and other suitable accessories in system  10  is merely illustrative. In general, any suitable accessories may be used in system  10  if desired. 
     Accessories such as headsets are typically connected to electronic devices using audio plugs (male audio connectors) and mating audio jacks (female audio connectors). Audio connectors such as these may be provided in a variety of form factors. Most commonly, audio connectors take the form of 3.5 mm (⅛″) miniature plugs and jacks. Other sizes are also sometimes used such as 2.5 mm subminiature connectors and ¼ inch connectors. In the context of accessories such as headsets, these audio connectors and their associated cables are generally used to carry analog signals such as audio signals for speakers and microphone signals. If desired, audio connectors may include optical communications structures to support optical signal traffic. 
     As shown in  FIG. 1 , path  16  may be used to connect electronic device  12  and accessory  14  at connections points  16 A and  16 B. In a typical arrangement, path  16  includes one or more audio connectors such as 3.5 mm plugs and jacks or audio connectors of other suitable sizes at connection points such as points  16 A and  16 B. Conductive lines in path  16  may be used to convey signals over path  16 . There may, in general, be any suitable number of lines in path  16 . For example, there may be two, three, four, five, or more than five separate lines. These lines may be part of one or more cables. Cables may include solid wire, stranded wire, shielding, single ground structures, multi-ground structures, twisted pair structures, or any other suitable cabling structures. 
     In a typical scenario, device  12  may be, as an example, a handheld device that has media player and cellular telephone capabilities. Accessory  14  may be a headset with a microphone and a user input interface such as a button-based interface for gathering user input. Path  16  may be a four conductor audio cable that is connected to devices  12  and  14  using 3.5 mm audio jacks and plugs (as an example). 
     The audio connectors that are used to interconnect device  12  and accessories such as accessory  14  may include audio plugs that mate with corresponding audio jacks. These connectors may be used at any suitable location or locations within path  16  such as locations  16 A or  16 B. For example, an audio jack can be formed within the housing of device  12  at location  16 A and mating plug on the end of cable  16  may plug into the jack at location  16 A. 
     An example of a suitable audio plug is a four-contact plug. A four-contact plug may have four conductive regions arranged along a cylindrical barrel that mate with four corresponding conductive regions in a four-contact jack. The region at the tip of the plug is sometimes referred to as the tip contact. The region at the opposing end of the plug is sometimes referred to as the sleeve contact. The two interposed regions are sometimes referred to as first and second ring contacts. Using this terminology, four-contact plugs are sometimes referred to as tip-ring-ring-sleeve (TRRS) plugs and their mating jacks are sometimes referred to as TRRS jacks. Jacks and plugs with different numbers of contacts (e.g., fewer than four or more than four) may also be used. In general, audio connectors in path  16  may be formed from any suitable plugs (male connectors) and any suitable jacks (female connectors) or any other suitable mating connectors. Moreover, connectors may be placed at any suitable locations along path  16 . With a typical arrangement, a jack is mounted within device  12  and a mating plug is connected to accessory  14  by a cable attached at location  16 B. This is, however, merely illustrative. A jack may be mounted in accessory  14  at location  16 B and a plug may be connected to device  12  via a cable at location  16 A. As another example, jacks may be used in both device  12  and accessory  14  and a double-ended cable (i.e., a cable with male connectors on either end) may be used to connect device  12  with accessory  14 . Adapters may also be used. For example, an adapter may be plugged into device  12  (e.g., using a digital port). The adapter, which may be considered to be a type of accessory  14 , may be provided with a jack into which a plug from a headset or other equipment may be inserted to complete path  16 . In this type of scenario, the adapter may contain circuitry for performing functions that would otherwise be performed by buttons and circuitry on the headset. 
     An illustrative accessory is shown in  FIG. 2 . Accessory  14  of  FIG. 2  is a headset with a microphone. Speakers  92  may be provided in the form of over-the-ear speakers, ear plugs, or ear buds (as examples). Dual-conductor wires such as wires  94  may be connected to speakers  92 . Button controller assembly  100  may include a microphone. In some applications, the microphone may not be needed and may therefore be omitted from accessory  14  to lower cost. In other applications, such as cellular telephone application, voice recording applications, etc., the microphone may be used to gather audio signals (e.g., from the sound of a user&#39;s voice). 
     In the  FIG. 2  example, button controller assembly  100  includes three buttons. If desired, more buttons, fewer buttons, or non-button user input devices may be included in accessory  14 . Moreover, it is not necessary for these devices to be mounted to the same unit as a microphone. The  FIG. 2  arrangement is merely illustrative. 
     In an illustrative three-button arrangement, a first of the three buttons such as button  102  may be pressed by a user when it is desired to advance among tracks being played back by a music application or may be used to increase a volume setting. A second of the three buttons, such as button  104  may be pressed when it is desired to stop music playback, answer an incoming cellular telephone call made to device  12  from a remote caller, or when it is desired to make a menu selection. A third of the three buttons such as button  106  may be selected when it is desired to move to an earlier track or when it is desired to lower a volume setting. Multiple clicks, click and hold operations, and other user input patterns may also be used. The up/down volume, forward/reverse track, and “answer call” examples described in connection with  FIG. 2  are merely illustrative. In general, the action that is taken in response to a given command may be adjusted by a system designer through modification of the software in device  12 . 
     As shown in  FIG. 2 , a cable such as cable  108  may be integrated into accessory  14 . At its far end, cable  108  may be provided with a connector such as audio connector  110 . In the  FIG. 2  example, accessory  14  has two speakers  92  and a microphone. Connector  110  may therefore be of the four-contact variety (i.e., a TRRS plug). In accessories in which the microphone or one of the speakers is omitted, signals can be carried over fewer lines (e.g., using a three-contact connector). If desired, connectors with additional contacts may also be used (e.g., to carry auxiliary power, to carry control signals, etc.). Audio connectors with optical cores can be used to carry optical signals in addition to electrical signals. 
     Accessory  14  may be provided with circuitry that helps convey signals from button controller unit  100  to device  12  over path  16 . In general, any suitable communications format may be used to convey signals (e.g., analog, digital, mixed arrangements based on both analog and digital formats, optical, electrical, etc.). These signals may be conveyed on any suitable lines in path  16 . To avoid the need to provide extra conductive lines in path  16  and to ensure that accessory  14  is as compatible as possible with standard audio jacks, it may be advantageous to convey signals over existing lines (e.g., speaker, microphone, and ground). In particular, it may be advantageous to use the microphone and ground lines (e.g., the lines connected to contacts such as ring contact  52  and sleeve S in audio plug  110 ) to convey signals such as user input signals and control signals between accessory  14  and electronic device  12 . 
     With one suitable communications arrangement, buttons such as buttons  102 ,  104 , and  106  may be encoded using different resistances. When a user presses a given button, device  12  can measure the resistance of user input interface  100  over the microphone and ground lines and can thereby determine which button was pressed. With another suitable arrangement, a button may be provided that shorts the microphone and ground wires in cable  108  together when pressed. Electronic device  12  can detect this type of momentary short. With yet another suitable arrangement, button presses within interface  100  may be converted to ultrasonic tones that are conveyed over the microphone and ground line. Electronic device  12  can detect and process the ultrasonic tones. These are merely illustrative examples. Any suitable communications circuitry may be provided in button controller assembly  100  to support communications between accessory  14  and device  12  if desired. 
     Moreover, electronic device  12  can support communications using two or more communications arrangements. Different approaches may be used, for example, to support both legacy hardware and new hardware, to support different types of software applications, to support reduced power operation in certain device operating modes, etc. 
     In the example of  FIG. 2 , button controller assembly  100  is located between path portion  124  and path portion  120 . In this type of arrangement, path  124  may contain four wires (for left audio, right audio, microphone, and ground), whereas path portion  120  may contain two wires (for ground and right audio). Path portion  122  may contain two wires (for ground and left audio). This is merely one illustrative example. Button controller assembly  100  may be located on any suitable portion of the wiring in accessory  14  if desired. For example, button controller assembly  100  may be placed at an intermediate location along path segment  108 , rather than between path segments  120  and  124  as shown in the example of  FIG. 2 . 
       FIG. 3  shows how accessory  14  may be provided in the form of an adapter that allows button functionality to be added to an accessory  130  that does not necessarily include button functionality. As shown in  FIG. 3 , headset  130  may have an audio plug  116  that plugs into a mating audio jack  114  on adapter accessory  14 . Plug  116  and jack  114  may be audio connectors such as tip-ring-sleeve (TRS) or TRRS connectors. Headset  130  may include speakers  92 , conductive paths  94  and optional components  132  (e.g., for a legacy button or microphone). 
     Adapter accessory  14  may include electrical paths that pass audio signals from device  12  to speakers in headset  130  and that pass microphone signals from a microphone to device  12  (e.g., a microphone in adapter  14  or in component  132 ). Adapter  14  may also include the circuitry that handles communications with device  12  over path  16  that would otherwise be included within the button controller assembly of a headset accessory. It is therefore not necessary for headset  130  in the  FIG. 3  arrangement to include this circuitry. In the  FIG. 3  example, headset  130  includes speakers  92  and may include microphone  132 , but need not include any buttons, because buttons  102 ,  104 , and  106  are included on accessory  14 . Accessory  14  may have a cable such as cable  108  with an audio connector  118  for plugging into a mating audio jack on device  12 . Adapter-type arrangements such as the arrangement of  FIG. 2  allow a user to add button functionality to an accessory such as a headset that does not include buttons. This may be particularly advantageous if a user already owns several different styles of buttonless headset, yet desires to use buttons such as buttons  102 ,  104 , and  106  to control electronic device  12  remotely. If desired, an adapter accessory such as accessory  14  of  FIG. 3  may be provided with a microphone. 
     Any suitable form factor may be used for button controller assembly  100 . An illustrative example is shown in  FIG. 4 . As shown in  FIG. 4 , button controller assembly  100  may be formed using an elongated housing structure. The housing may have multiple parts. For example, the housing for button controller assembly  100  may have an upper portion such as portion  200  and a lower portion such as portion  202 . Cable  204  may protrude from either end of button controller assembly  100 . 
     In the  FIG. 4  example, button controller assembly  100  contains three button regions. Button region  102  has been labeled “+” to indicate to the user that this region forms a button that may be pressed when it is desired to increase a playback volume or take other such appropriate actions. Button region  104  may be used in forming a button that performs functions such as pausing playback or other suitable actions. Button region  106  has been labeled “−” to indicate to the user that button region  106  forms a button that may be pressed when it is desired to decrease a playback volume or take other appropriate actions. 
     Upper housing portion  200  and lower housing portion  202  may be attached to internal structures. For example, upper housing portion  200  and lower housing portion  202  may be rigidly or movably connected to a frame such as frame  206 . Frame  206  may have structures that engage cable  204  and that help support housing sections  200  and  202 . 
     Housing portions  200  and  202  and frame  206  may be formed from any suitable material. As an example, some or all of housing portions  200  and  202  and frame  206  may be formed from plastic such as a blended plastic formed from polycarbonate and acrylonitrile butadiene styrene (i.e., PC/ABS plastic). With one suitable arrangement, housing portions  200  and  202  may be formed from multiple shots of plastic. For example, housings  200  and  202  may be formed using a double shot molding process. With this type of arrangement, different portions of each housing may be formed from different plastics. This allows different portions of each housing to be provided with individually tailored materials properties. These properties may include, for example, different textures, different colors, different rigidities (i.e., different flexibilities), different durability levels, etc. 
     As an example, it may be desired to form the portion of housing  200  such as the portion in region  104  from a plastic that is more textured than the plastic in regions  102  and  106 . This may help the user of button controller interface  100  recognize when the user&#39;s finger is on top of region  104 . As shown in  FIG. 4 , the surface of housing  200  in region  104  may also be recessed with respect to the surface of housing  200  in regions  102  and  106  to facilitate user identification of each button region. 
     As another example, snaps and other features on the interior portions of housings  200  and  202  may be formed from plastics that are more rigid than other housing portions. With this type of approach, some structures may be formed from a plastic that is flexible enough to deform under user finger pressure, while other structures (e.g., snaps and other interior engagement structures) may be rigid enough to exhibit desired levels of durability and strength. 
     The housings, frame, and other structures of button controller assembly  100  may be configured to allow housing portions  200  and  202  to float relative to each other when a user actuates a desired button. One or both housing portions may also flex along their lengths. When floating, structures in the housings are captured by each other which limits the maximum amount of permissible travel. As an example, a snap feature may protrude into a hole or be captured by a rail. The housings can float (freely move) with respect to each other, so long as the snap does not bear against the edges of the hole or rail. Once the snap bears against a hole or rail edge (in this example), the maximum amount of permissible travel has been reached and further travel will be impeded. Housing portions that flex allow additional flexing movement beyond what would be permitted solely by the “float” between the housing portions. 
     With one illustrative configuration, upper housing  200  and frame  206  may be rigidly attached to each other, whereas lower housing  202  may be allowed to move relative to upper housing  200  (i.e., float) when a user squeezes a desired one of the buttons formed by regions  102 ,  104 , and  106 . Lower housing  200  may also flex somewhat when a user squeezes assembly  100  by pressing a desired one of the buttons. This flexibility can help accommodate selection of an individual button without inadvertently activating other buttons. 
     As shown in the perspective view of  FIG. 5 , button controller assembly  100  may have a length L that is greater than its width W and thickness T. In an illustrative configuration, length L may be about 28 mm, width W may be about 5.19 mm, and thickness T may be about 3.34 mm. The thickness of housing  200  may be about 0.4 mm and the thickness of housing  202  may be about 0.4 mm. Cable  204  may have a diameter of about 1.6 mm. 
     Button controller assembly  100  may include a microphone. Because there are generally air gaps between the various housing members and other structures in assembly  100 , it is typically possible for sound to reach the interior of button controller assembly  100  without providing a separate microphone port. As a result, button controller assembly  100  may, if desired, be provided with no specialized microphone port. Sound from the exterior of assembly  100  may reach the interior of assembly  100  through air gaps such as air gap  208  between housing  202  and housing  200 , air gap  210  between housing  202  and frame  206 , and air gap  212  between housing  200  and frame  206 . These gaps may be present at both ends of assembly  100  and on either side of assembly  100 . When gaps such as these are present, the microphone in assembly  100  may be mounted in the interior of assembly  100  without providing additional holes in housings  200  and  202 . 
     Although it is possible to mount a microphone within assembly  100  without providing a dedicated microphone port, it is possible that a user of button controller assembly  100  might become confused as to whether button controller assembly  100  contains a microphone. To avoid user confusion, it may therefore be desirable to provide button controller assembly  100  with a visual indicator that informs the user of the presence of the microphone. 
     In the example of  FIG. 5 , lower housing  202  has been provided with a nonoperational microphone port  214  that serves as a visual indicator of the presence of a microphone within button controller assembly  100 . Port  214  may be provided with a perforated metal disk such as disk  218 . Housing  202  may be provided with a circular recess into which disk  218  may be mounted. Circular recess  216  and disk  218  may each have a diameter of about 1.57 mm (as an example). Disk  218  may be formed from a metal plate (e.g., stainless steel) that is about 0.1 mm in thickness and that has holes of about 0.209 mm in diameter. The holes may be formed in disk  218  by chemical etching or other suitable fabrication techniques. If desired, disk  218  may be formed from a wire mesh or a fabric. 
     Disk  218  may be mounted within circular recess  216  using double-sided adhesive film (tape). Circular recess  216  may have a closed bottom with no holes, so sound does not flow through port  214 . In this type of configuration, port  214  is not functional as a microphone port, but serves instead as a visual indicator to the user that a microphone is present within button controller assembly  100 . If desired, a functional microphone port that includes a wire mesh may be provided in assembly  100  in addition to or instead of nonoperational port  214 . Moreover, other types of visual indicators may be used to indicate to the user that the microphone is present in button controller assembly  100 . For example, a printed shape in the form of a label, a microphone symbol, or a microphone port may be provided on the exterior of the housing of assembly  100 . A suitable visual indicator may also be provided by using an appropriately colored plastic portion within the housing of assembly  100  or other visual indicators may be used. 
       FIG. 6  shows an exploded perspective view of button controller assembly  100 . As shown in  FIG. 6 , lower housing  202  may be formed from two different types of plastic using a two-shot injection molding process. A first plastic may be used to form housing portion  202 A. A second plastic may be used to form housing portion  202 B. Portion  202 B may, for example, be formed from a more durable and less flexible plastic than portion  202 A. This may help to allow portion  202 A to flex along its length when pressed by a user, while ensuring that portions  202 B are sufficiently rigid to serve as engagement structures. If desired, portions  202 A and  202 B may be formed from plastics that have similar or equal rigidities. 
     Plastic portions  202 A and  202 B may have different textures or colors. A darker color may be preferred for portions  202 B, because these portions of housing  202  may be visible through the air gaps in the housing (e.g., air gaps  210  and  212  of  FIG. 5 ) when button controller assembly  100  is fully assembled. Portions  202 B may be configured to form snaps or other engagement structures that help to attach housing  202  to button assembly  100 . 
     Center snap member  220  may be formed of a material such as metal. An example of a suitable metal for member  220  is stainless steel. Stainless steel or other such materials may be used for member  220  so that member  220  may serve as a durable surface against which button switches may bear during operation of button controller assembly  100 . 
     Holes  222  in member  220  may mate with corresponding heat stake portions on the inside of housing  202 . Member  220  may be attached to housing  202  by melting the outermost portions of the heat stakes after holes  222  have been placed over the heat stakes. Tabs  224  may have holes that engage snaps or other engagement structures that are part of housing  200  or that are attached to housing  200 . For example, housing portion  200  and frame  206  may be rigidly connected to each other so that frame  206  becomes a part of housing portion  200  and holes in tabs  224  of member  220  such as hole  248  may mate with corresponding snaps or other engagement features on frame  206  such as snap  250 . 
     Dome switch assembly  228  may be used to provide button controller assembly  100  with user-controllable button switches. As shown in  FIG. 6 , dome switches  226  such as dome switches  226 A,  226 B, and  226 C may be mounted on printed circuit board  230 . Integrated circuits and other circuitry  232  such as a microphone may be mounted on the opposite side of printed circuit board  230 . Circuitry  232  may be electrically connected to dome switches  226 . When button controller assembly  100  is assembled, switch  226 A is longitudinally and laterally aligned with region  102  and switches  226 B and  226 C are aligned with regions  104  and  106  respectively. When a user squeezes a given region, the corresponding portion of housing  202  is pressed inwardly. As this portion of housing  202  moves inwardly, a corresponding portion of member  220  is forced against the nub on an appropriate one of dome switches  226 . Because member  220  is formed of metal (in one suitable arrangement), the nub will not dig into member  220  over time, as might occur if the nub were to bear against a soft plastic. 
     Nubs  242  may, if desired, be coated with a durable material such as epoxy to help ensure crisp switch actuation events. Dome switches  226  may each have a circular metal dome portion on which a nub is formed. The metal domes may be held in place on dome switch assembly  226  using clear tape. On their inner surfaces, the dome switches may have traces that connect to corresponding traces in the printed circuit board  230 . Adhesive film may be used to attach the dome switches to printed circuit board  230 . 
     To ensure that the dome switch will be actuated when the user squeezes assembly  100 , the snaps and other engagement features that are used to attach the various portions of assembly  100  together may be provided with sufficient clearances to allow housing  202  to float (travel) unimpeded. The maximum permitted amount of travel between the two floating pieces of assembly  100  may be, for example, 0.15 mm to 0.2 mm in the vertical direction. 
     If the user presses region  104  (as an example), the central region of housing  202  will be forced inward against switch  226 B to actuate switch  226 B. During actuation, housing  202  travels inwardly towards frame  206  and housing  200 . Housing  202  also preferably flexes, so that the ends of housing  202  (and therefore the associated end portions of member  220 ) are not pressed significantly inwards while the central region of housing  202  travels inward. This is accomplished by ensuring that dome switches  226 A and  226 B and structures  256  of housing portion  200 B press outwardly with sufficient force to resist the inward movement of housing  202  that is produced while the central portion of housing  202  is being pressed inwardly against switch  226 B. As this example demonstrates, button housing  220  preferably has both a free range of travel that results from using snaps and other engagement features that do not rigidly attach housing  202  to frame  206  and a flexibility that accommodates individual button selections without inadvertently actuating more than one dome switch  226  at a time. 
     Spring members such as spring members  236  may be provided to help bias housing  202  outwardly away from frame  206  and housing  200 . Spring members  236  may be formed from any suitable material. As an example, spring members  236  may be formed from an elastomeric material such as silicone and may therefore sometimes be referred to as rubber gaskets. Spring members  236  may fit into recesses within frame  206 , straddling cable  204 . The outermost portions of spring members  236  may be curved so that they press evenly against the inner surface of housing portion  202 A. Spring members  236  may be located at the ends of assembly  100  or any other suitable locations along the length of assembly  100 . Particularly when located at the ends of assembly  100 , spring members  236  may serve as cosmetic shrouds by helping to shield the interior portion of assembly  100  from view. Any suitable number of spring members  236  may be used in assembly  100  (e.g., one, two, three, more than three, etc.). 
     Circuitry  232  may detect which dome switch is actuated by the user and may transmit corresponding signals to device  12  over wires in cable  204 . As shown in  FIG. 6 , some of the wires in cable  204  such as wire  234  pass through button controller assembly  100  (i.e., to route speaker signals to a speaker), whereas other wires may be soldered onto pads on printed circuit board  230 . Metal crimp structures such as crimp bands  205  may be crimped to the ends of cable  204 , to prevent cable  204  from being withdrawn from frame  206 . 
     When fully assembled, portions  202 B of housing  202  may engage portions of frame  206 . For example, snap  238  may engage rail portion  240  of frame  206  and snap  246  may engage rail portion  244  of frame  206 . Member  220  may be heat staked to housing  202  and may have tabs  224  with holes that engage with mating features in frame  206 . The holes in tabs  224  such as hole  248 , the mating engagement feature on frame  206  (e.g., snap  250 ), and the respective mating engagement features on housing portion  202 B and frame  206  are preferably configured to allow vertical travel (e.g., 0.15 mm to 0.2 mm of floating travel) between housing  202  and frame  206  (and thereby housing  200 ) when a button is actuated. At least some of the engagement features in button controller assembly  100  may be formed exclusively from plastic parts. For example, the plastic engagement structure formed by snap  238  may mate with plastic rail portion  240  without using any metal parts. Structures such as snap  238  may be sufficiently flexible to flex laterally inward during assembly (e.g., by about 0.3 mm to ride over rails such as rail  240  in frame  206 ). 
     Frame  206  may be rigidly attached to housing portion  200 . Alignment structures  252  may help to longitudinally align frame  206  with housing  200 . When properly aligned, ridges  254  on frame  206  run along the inner surface of housing  200  adjacent to alignment structures  252 . Ridges  254  may be bonded with housing  200  using ultrasonic welding, thereby forming a unitary structure in which frame  206  rigidly attached to housing  200  and does not travel significantly with respect to housing  200 . Although button labels (i.e., the “+,” recess, and “−”) are provided on upper housing  200  rather than lower housing  200  in the example of  FIGS. 4 ,  5 , and  6 , during button actuation, housing  202  travels and flexes inwardly against dome switches  226 , rather than housing  200 . Dome switches  226  are preferably held rigidly against housing  200 , so that a desired dome switch nub may be depressed by the user. 
     Housing  200  may, if desired, be formed from a double shot molding process. This allows portions  200 B to be formed from a different plastic than portions  200 A. Portions  200 B may, for example, be formed from a plastic that is darker in color than portions  200 A. This helps to reduce the visibility of portions  200 B through air gaps such as gaps  208  and  210  ( FIG. 5 ) and helps to increase the visibility of portion  200 B in region  104  on the outermost surface of assembly  100  (as shown in  FIG. 4 ). Features  256  form support structures for integrated circuits  232  and subassembly  228  and structures that bear against the inner portion of housing  202  when squeezed to help separately define button regions  102 ,  104 , and  106 . End portions  258  of frame  206  serve as environmental seals and cosmetic covers that help to block the user&#39;s view of the interior of button controller assembly  100 . 
     A cross-sectional side view of button controller assembly  100  of  FIG. 5  when assembled for use in system  10  is shown in  FIG. 7 . 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.