Patent Publication Number: US-9432772-B2

Title: Methods and apparatus for porting loudspeakers to an earpiece

Description:
TECHNICAL FIELD 
     The technical field relates generally to methods and apparatus for configuring loudspeakers and their associated bass reflex outputs for use with a telephone handset, and more particularly to porting primary and bass reflex loudspeaker output to an earpiece. 
     BACKGROUND 
     Consumers increasingly desire to listen to telephone conversations through a private mode earpiece, and to otherwise view and listen to media on a variety of devices, such as mobile telephone handsets, gaming consoles, ebooks, MP3 and other audiovisual display and playback devices, personal digital assistants (PDAs), and numerous other computing and telecommunication devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  is a schematic diagram of a telephone handset including a speaker having a primary output and a bass reflex output ported to an earpiece in accordance with an exemplary embodiment; 
         FIG. 2  is a schematic diagram of dual loudspeakers in bass reflex enclosures at opposite ends of a telephone to support landscape stereo mode in accordance with an exemplary embodiment; 
         FIG. 3  is a schematic diagram illustrating the active port of the top speaker and the bass reflex port of the bottom speaker ported to the earpiece in accordance with an exemplary embodiment; 
         FIG. 4  is a schematic diagram illustrating the handset of  FIG. 3  with the top speaker bass reflex port blocked in accordance with an exemplary embodiment; 
         FIGS. 5-8  are graphs plotting speaker output versus frequency for various configurations of dual speakers in ported enclosures in accordance with exemplary embodiments; and 
         FIG. 9  is a schematic block diagram of a signal processing architecture for use with dual speakers in ported enclosures in accordance with exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the application and uses of the wearable device described herein. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
     Broadly, exemplary embodiments disclosed herein provide systems and methods for porting loudspeakers to an earpiece in a telephone handset. A hand-held electronic device is provided which includes an earpiece, a first speaker having a first primary audio output ported to the earpiece, and a second speaker having a second primary audio output and a second bass reflex output, wherein the second bass reflex audio output is also ported to the earpiece. A “use case manager” decides how the audio configured based on what is being played back. The use case management module may be configured to respond to user action: for example, if the user answers or places a call, the use case manager can select private mode unless the user selects speaker mode for the call. If, on the other hand, the user launches a video or an audio file, the use case management module can select landscape (broadcast) mode. 
     In an embodiment, the device has a first region and a second region remote from the first region and the first speaker includes a first bass reflex audio output. The first primary audio output is disposed proximate the second bass reflex audio output in the first region, the second primary audio output is disposed proximate the first bass reflex audio output in the second region, and the earpiece is disposed in the first region. 
     In another embodiment, the speaker volume in broadcast mode is substantially louder than the speaker volume in private mode. Broadcast mode may be monophonic or stereophonic, and private mode is preferable monophonic. 
     A display such as a flat screen video monitor may be positioned disposed between the first and second regions, such that the first position corresponds to a landscape viewing mode and the second position corresponds to a telephone mode (or private mode) of operation. The sensor may be a motion sensor such as an accelerometer. 
     In a further embodiment, the first speaker system includes a first audio transducer and the second speaker system includes a second audio transducer; the first primary audio output is located on an output side of the first audio transducer and a first volume portion is located on a reflex side of the first audio transducer; the second primary audio output is located on an output side of the second audio transducer and a second volume portion is located on a reflex side of the second audio transducer; the first bass reflex audio port is connected to the first volume portion through a first port extending from the first region to the second region; and the second bass reflex audio port is connected to the second volume portion through a second port extending from the first region to the second region. 
     In an embodiment, a shutter may be configured to block the first bass reflex output when the device is in broadcast mode. The shutter may be an electronic switch or, alternatively, a manually actuable (e.g., slidable) mechanism. 
     The controller may include a filter and a polarity inverter, and the controller may be configured to apply a first signal to the first speaker and a second signal to the second speaker. In one embodiment, the controller is configured to: apply the first and second signals in phase to the first and second speakers, respectively, for all frequencies when the device is operating in said broadcast mode; apply the first and second signals in phase for all frequencies above a predetermined threshold when the device is operating in private mode; and apply the first and second signals out of phase to the first and second speakers, respectively, for all frequencies below the predetermined threshold when the device is operating in private mode. 
     In one embodiment, the predetermined threshold generally corresponds to the resonant frequency of the first and second bass reflex outputs, which may be in the range from about 200 to about 400 Hertz, and particularly about 300 Hertz. 
     In a further embodiment, a handset includes an earpiece; a first speaker having a primary output ported to the earpiece; a second speaker having a bass reflex output ported to the earpiece and tuned to a resonance frequency; and a controller configured to apply a signal to the second speaker, the signal having a high frequency component at a first phase and a low frequency component at a second phase. In a preferred embodiment, the high frequency component is above the resonance frequency and the low frequency component is below the resonance frequency, wherein the resonance frequency may be in the range of about 300 Hertz. A filter may be employed to limit the signal to within the range of the resonance frequency. 
     In yet a further embodiment, a method of porting audio signals to an earpiece of a telephone operating in private mode is provided. The method includes applying a primary audio output of a first speaker to the earpiece; applying a bass reflex audio output of a second speaker to the earpiece; applying a first electronic signal to the first speaker; and applying a second electronic signal to the second speaker, wherein the second electronic signal has a first frequency component at a first phase, and a second frequency component at a second phase which is inverted with respect to the first phase. In this way, the primary output of the first speaker and the bass reflex output of the secondary speaker are in phase throughout the frequency range of interest for both speakers. The method may also involve blocking a bass reflex output of the first speaker. 
       FIG. 1  is a schematic diagram representation of a telephone handset  100  including a speaker having both a primary output and a bass reflex output ported to an earpiece in accordance with an exemplary embodiment. Although exemplary embodiments are discussed below with reference to hand-held and portable electronic devices, the systems and methods discussed herein are equally applicable to any type of device having one or more speakers and an earpiece. 
     In the embodiment shown in  FIG. 1 , handset  100  includes a housing  102  enclosing a speaker assembly  104 . Speaker assembly  104  includes a transducer  112  (such as, for example, an acoustic diaphragm), a bass reflex chamber  106 , a bass reflex port (conduit)  108 , and a bass reflex audio output portion  110 . Transducer  112  produces a primary audio output on one side (out of the page in  FIG. 1 ) and a bass reflex output on the opposite side (into the page in  FIG. 1 ). The bass reflex output is produced by a tuned combination of chamber  106  and port  108 . 
     In particular, the air volume within chamber  106  functions as a mechanical spring and the air volume within port  108  functions as a movable mass; together, chamber  106  and port  108  may be modeled as a mass/spring combination, as is known in the art. The bass reflex output terminates at an open end of port  108 , namely, bass reflex audio output portion  110 . In the embodiment shown in  FIG. 1 , bass reflex audio output portion  110  and the primary audio output from the front side of speaker  104  are both routed (ported) into an earpiece  114  configured to be held against the user&#39;s ear during private mode use, that is, when device  100  is operated as a telephone handset. 
     The geometric configuration of the bass reflex output system described above may be “tuned”—or optimized—to provide desired frequency response characteristics from the combined outputs of the primary and bass reflex outputs from speaker  104 . More particularly, the various components may be configured such that the resonance frequency of the combined primary/bass reflex outputs is in the range of 100-450 Hertz, and particularly around 250-350 Hertz, and preferably about 300 Hertz. 
       FIG. 2  is a schematic diagram of a handset  200  including first and second speakers  202 ,  204 , respectively, in bass reflex enclosures at opposite ends of the handset to support landscape stereo mode. Speaker  202  includes a transducer  206  and a bass reflex system  208  having a chamber and a port  212  extending from the chamber and terminating at a bass reflex port  214 . Speaker  204  includes a transducer  216  and a bass reflex system  218  having a chamber and a port  222  extending from the chamber and terminating at a bass reflex port  224 . As shown in  FIG. 2 , the bass reflex port of one speaker is configured to terminate near the primary output of the opposing speaker. 
     With continued reference to  FIG. 2 , in one embodiment the two speaker systems/porting systems may be symmetrical; that is, the speakers are identical and disposed at opposite ends of the device for broadcast use, such as, for example, when the device is used for playing music, videos, and the like. 
     Referring now to  FIG. 3 , a schematic diagram similar to that of  FIG. 2  illustrates a novel porting architecture wherein the active (primary) port of the top speaker and the bass reflex port of the bottom speaker are both ported to the earpiece. 
     More particularly, a handset  300  includes first and second speakers  302 ,  304 , respectively, an earpiece  310 , a screen display and/or touch screen monitor  306  for viewing text, images, graphics, and/or video, and a sensor (detector)  312  (or a use case management module) for determining whether a horizontal/landscape or vertical/telephone mode of operation is desired. First speaker  302  includes a bass reflex output port  303  terminating near second speaker  304 . Second speaker  304  includes a bass reflex output port  308  which terminates near first speaker  302 . The primary audio output of first speaker  302 , as well as the bass reflex output port  308  of second speaker  304 , are both ported to earpiece  310 . 
     With continued reference to  FIG. 3 , when sensor  312  detects that handset  300  should be used in a landscape mode (e.g., a substantially horizontal orientation), first and second speakers  302 ,  304 , may be symmetrically operated at a relatively high volume (sometimes referred to herein as “broadcast” mode) such that the user can conveniently hear the audio output from a distance (e.g., at an arm&#39;s length). Conversely, when detector  312  determines that it is appropriate to drive the audio for telephone use (e.g., a substantially vertical orientation), the speakers may be operated at a relatively low volume referred to herein as private mode. In private mode, the primary audio output of first speaker  302  and the bass reflex audio output  304  are simultaneously ported to earpiece  310 . 
     Notably, either or both speakers can be operated in stereophonic or monophonic mode when the device is operated in broadcast mode, and either or both speakers can be operated in stereophonic or monophonic mode when the device is operated in private mode. Moreover, either or both of the bass reflex ports can be blocked or unblocked in both broadcast and private modes, as desired. 
     Referring now to  FIG. 4 , a handset  400  includes a top speaker  402  having a bass reflex port  406 , a bottom speaker  404  having a bass reflex port  408 , and an earpiece  410 . The primary audio output of top speaker  402  and the bass reflex output from bottom speaker  404  are ported to earpiece  410 . The handset configuration of  FIG. 4  differs from that of  FIG. 3 , however, in that bass reflex port  406  may be selectively blocked, for example, through the use of a shutter  412 . Shutter  412  may be a mechanical shutter, switch, or the like, and may be manually or electronically actuated to shut off bass reflex port  406 . 
       FIGS. 5-8  are graph plotting speaker output versus frequency for various configurations of dual speakers in ported enclosures. With particular reference to  FIG. 5 , a dashed line  502  represents the output of top speaker  402  with its bass reflex port  406  unblocked, and without contribution from bass reflex port  408 . The ‘dip’ (corresponding to a local minimum  503 ) near 300 Hertz represents reduced diaphragm movement at the resonance frequency of the bass reflex port (typically in the range of 300 Hertz for cellular telephones). A solid line  504  represents the output of speaker  402  with its bass reflex port blocked. As shown in  FIG. 5 , blocking the bass reflex port has the effect of smoothing the speaker output near the bass reflex resonance frequency. 
       FIG. 6  is a graph  600  which is substantially identical to  FIG. 5 , but with the addition of a line  606  representing the contribution (in the vicinity of earpiece  410 ) from bass reflex port  408 . Note the increased energy available from bass reflex port  408  near 300 Hertz. 
       FIG. 7  is a graph  700  which is substantially identical to  FIG. 6 , but with the addition of a line  708  representing the addition (in the vicinity of earpiece  410 ) of lines  504  and  606 ; that is, line  708  corresponds to the summation of: i) the primary audio output of speaker  402  with its bass reflex port  406  blocked; and ii) the contribution from bass reflex port  408  (in the vicinity of earpiece  410 ). Observe that the summation (line  708 ) yields more energy at port resonance (around 300 Hertz) and above, but that below 300 Hertz the summation exhibits a reduced total energy. This is due to the relative phase of the bass reflex port ( 408 ) contribution vis-à-vis the primary output of speaker  402 . 
     Turning now to  FIG. 8 , a graph  800  is substantially identical to  FIGS. 6 and 7 , but with the addition of a line  810  in lieu of line  708 . Line  810  represents the summation of the primary output of speaker  402  (with its bass reflex port  406  blocked) and the contribution from bass reflex port  408 , but with the signal polarity of speaker  404  (and, hence, port  408 ) reversed. As a result of the inverted polarity of port  408  vis-à-vis speaker  402 , the combination (summation) of lines  504  and  606  below 300 Hertz is greater than either speaker  402  or port  408  alone. Above 300 Hertz, however, line  810  (the summation with reversed polarity) is less than line  708  (summation with the same polarity). 
     With continued reference to  FIGS. 7 and 8 , by reversing the relative polarity of speakers  402  and  404  below the port resonance frequency (e.g., in the range of 300 Hertz), but maintaining the same polarity above port resonance, the combined energy near earpiece  410  is greater than each respective contribution for frequencies ranging from 100 Hertz to 1 Kilohertz and above. 
       FIG. 9  is a schematic block diagram of a signal processing architecture for use with dual speakers in ported enclosures in accordance with exemplary embodiments. More particularly, a processing architecture  900  includes a detector  902  (analogous to use case management module  312  in  FIG. 3 ), an amplifier  904 , and a control module  930 . Processing architecture  900  includes a first speaker  910  (analogous to top speaker  402  in  FIG. 4 ) and a second speaker  912  (analogous to bottom speaker  404  in  FIG. 4 ) having a bass reflex port  914  (analogous to port  408  in  FIG. 4 ). For clarity, the bass reflex port is omitted from  FIG. 9  for speaker  910 . In the illustrated embodiment, the primary audio output of speaker  910  and the bass reflex audio output from port  914  may both be ported (routed) to an earpiece  916  when the handset is operated in private mode. 
     Detector  902  is configured to determine whether the audio should be driven in landscape mode or telephone mode. Detector  902  may be configured to apply a signal  903  to amplifier  904  to indicate the mode of operation of the device. Amplifier  904  outputs a first drive signal  906  corresponding to first speaker  910 , and a second drive signal  908  corresponding to second speaker  912 . Depending on the value of signal  903 , amplifier may generate signals  906 ,  908  at a relatively high volume level (broadcast mode) or a relatively low volume level (private mode). 
     In order to implement the polarity reversal discussed above in conjunction with  FIGS. 7 and 8 , second speaker signal  908  is applied to control module  930 . More particularly, control module  930  includes a filter  932 , for example, a low pass or band pass filter, a frequency detector or band splitter  934 , and an all pass or phase shifting circuit  936  which may be implemented via an IIR filter to invert phase of the port output so as to match the phase of the primary speaker. In operation, and particularly during private mode, filter  932  may be configured to generate a signal  933  which is a band limited version of signal  908 . 
     In one embodiment, signal  933  may be narrowly limited to the frequency range surrounding the bass port resonance frequency of speaker  912 , e.g., about 100 to 450 Hertz, and preferably about 250 to 350 Hertz. Splitter  934  may be implemented as a combination high pass and low pass filter, such that filter  934  outputs a signal  937  representing the component of signal  908  above a threshold value T (corresponding to port resonance), and a signal  935  representing the component of signal  908  below threshold value T. Inverter  936  may be configured to invert the phase of signal  935  relative to the phase of signal  937 , and to output an inverted signal  939  as discussed above. Both the high frequency component (signal  937 ) and the inverted low frequency component (signal  939 ) of second speaker signal  908  (or, alternatively, the of band limited signal  933 ) may then be applied as a drive signal  938  to second speaker  912 . 
     It is understood that the use of relational terms such as first and second, top and bottom, and the like, if any, are used to distinguish one from another entity, item, or action without necessarily requiring or implying any actual such relationship or order between such entities, items or actions. Much of the functionality and many of the principles are best implemented with or in software programs or instructions. It is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs with minimal experimentation. Therefore, further discussion of such software, if any, will be limited in the interest of brevity and minimization of any risk of obscuring the principles and concepts described herein. 
     As understood by those in the art, controller  204  includes a processor that executes computer program code to implement the methods described herein. Embodiments include computer program code containing instructions embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other computer-readable storage medium, wherein, when the computer program code is loaded into and executed by a processor, the processor becomes an apparatus for implementing the methods and apparatus described herein. 
     Embodiments of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Embodiments may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. A computer program, such as the computer program(s) described above, can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. Generally, a computer also may include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in special purpose logic circuitry. 
     Method steps may be performed by one or more programmable processors executing a computer program to perform functions by operating on input data and generating output. Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). 
     It will be appreciated that the above description for clarity has described various embodiments with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units or processors may be used. For example, functionality illustrated to be performed by separate processors or controllers may be performed by the same processor or controllers. Hence, references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the devices and methods described herein. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing exemplary embodiments. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.