Abstract:
A portable electronic device having a speaker module is provided. The speaker module includes: a speaker unit; a back chamber; an acoustic region coupled between the speaker unit and the back chamber; and a porous material at least partially filling a portion of the front chamber, the back chamber, or the channel, for improving and extending bass performance and relieving a acoustic effect caused by the acoustic region coupling the speaker unit and back chamber. Moreover, the portable electronic device is advantageously able to compensate a resonance degradation caused by the porous material.

Description:
This application is a continuation of U.S. application Ser. No. 13/787,540, filed Mar. 6, 2013, the subject matter of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a portable electronic device, and more particularly, to a portable electronic device with a speaker module filled with a porous material. 
     2. Description of the Related Art 
     In the information age, our reliance on electronic products can be seen everywhere. For example, we use mobile phones, computers and audio-visual products every day. As manufacturing techniques for electronic devices continue to advance, more personalized and multi-functional electronic products are available in the market. With big leaps in communication industry technology, the mobile phone has become increasingly common in our society. 
     Starting out being bulky and heavy, the first generation of mobile phones has transformed into slim and lightweight phones. Despite, most manufacturers are still researching methods to reduce the weight and size of existing mobile phones for greater portability. In the meantime, manufacturers are also trying hard to expand the function of each mobile phone and reduce as much as possible any harmful effects which may be caused to a user due to electromagnetic radiation. However, reducing the size of an existing mobile phone involves a close matching requirement of all the elements within the mobile phone including the location and size of a speaker box for housing a speaker unit. In fact, quality of sound emitted from the phone largely depends on the size of the speaker box. In general, a larger speaker box can obtain a better sound quality. Nevertheless, due to the miniaturization trend of the hand-held electronic device, a large size speaker box is no longer practical. Hence, how to devise a speaker box that can improve the sound quality while not increasing its size, is an important topic for manufacturers of portable devices. However, when a mobile phone is reduced in size, a speaker box within the mobile phone must be reduced correspondingly. Thus, the frequency response of the speaker module will deteriorate. 
     BRIEF SUMMARY OF THE INVENTION 
     Portable electronic devices and a method for operating a portable electronic device are provided. An embodiment of a portable electronic device having a speaker module is provided. The speaker module comprises: a speaker unit; a back chamber; an acoustic region coupled between the speaker unit and the back chamber; and a porous material at least partially filling a portion of the front chamber, the back chamber, or the channel, for improving/extending bass performance and relieving a channel effect impact. 
     Furthermore, another embodiment of a speaker module is provided. An embodiment of a portable electronic device is provided. The portable electronic device comprises: a housing; a speaker module at least partially filled with a porous material; at least one memory; a central processing unit; and a speaker amplifier for receiving the audio input, compensating the audio input according to a first peak and/or a second peak, and producing an audio output to the speaker module. 
     Moreover, an embodiment of a method operating an electronic portable device having a speaker module at least partially filled with a porous material is provided. The method comprises: requesting to drive the speaker module based on an audio input; predicting a sound pressure level degradation around a resonance frequency caused by the porous material; compensating the audio input according to the predicted sound pressure level degradation; and producing an audio output to drive the speaker module according to the audio output. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  shows an embodiment of a portable device; 
         FIG. 2  shows a sectional view of a portable device according to an embodiment of this application; 
         FIG. 3A  shows a schematic diagram illustrating a 50% fill rate of the porous material PM disposed in the speaker module of  FIG. 2 ; 
         FIG. 3B  shows a schematic diagram illustrating a 100% fill rate of the porous material PM disposed in the speaker module of  FIG. 2 ; 
         FIG. 4A  shows a frequency characteristic chart illustrating differences between a speaker module without porous material and a speaker module with the porous material PM according to an embodiment of this application; 
         FIG. 4B  shows an impendence characteristic chart illustrating the impendence characteristic corresponding to the frequency characteristic of  FIG. 4A ; 
         FIG. 5  shows an amplifier for increasing SPL around the resonance frequency according to an embodiment of this application; 
         FIG. 6  shows a processing method for the amplifier of  FIG. 5  according to an embodiment of this application; 
         FIG. 7  shows a speaker amplifier for increasing SPL around the resonance frequency according to another embodiment of this application; and 
         FIG. 8  shows a method for operating a portable electronic device of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
       FIG. 1  shows a portable device  100  according to an embodiment of a playback mechanism. The portable device  100  comprises a central processing unit (CPU)  110 , a speaker amplifier  120 , a speaker module  130 , a housing  140 , and at least one memory  150 . The at least one memory  150  can comprise a buffer inside and/or outside the CPU  110  and/or speaker amplifier  120 , for storing a multimedia file. The CPU  110  is for playing the multimedia file to produce an audio input corresponding the playing of the multimedia file. The CPU  110  provides an input signal Sin as an audio input to the speaker amplifier  120 , wherein the input signal Sin is a digital audio signal to be converted into an analog output signal Sout with the speaker amplifier  120 , and the output signal Sout is to be driven on the speaker module  130  to produce audible sounds. Since the speaker module is formed in a thin and/or elongated structure, a channel effect may be induced at certain frequency. The speaker module  130  is at least partially filled with a porous material to improve and extend bass performance. Furthermore, the at least one memory  150  stores a first peak corresponding to a resonance frequency and/or a second peak corresponding to a standing wave frequency, wherein the first and second peaks are caused by the porous material and a channel effect caused by the structure of the speaker module respectively. The speaker amplifier  120  is for receiving the audio input, compensating the audio input according to the first peak and/or the second peak, and producing an audio output to the speaker module  130 . The speaker amplifier  120  amplifies and modulates the input signal Sin based on the first peak and/or the second peak to solve resonance frequency degradation issue caused by the porous material.  FIG. 2  shows a sectional view of a portable device  200  according to an embodiment. The portable device  200  comprises a CPU  210 , a speaker amplifier  220 , a speaker module  230  and a housing  240 . The housing  240  for the portable device  200  comprises an audio output port  244 . The speaker module  230  is provided internal to the housing  240  and disposed in a side  250  of the housing  240 . The speaker module  230  comprises a speaker unit  234 , a channel  236 , a back chamber  238 , and a front chamber  242 . The front chamber  242  is a first acoustic chamber  242  internal to the housing  240  and defined by a front sidewall, having a first exit opening  232  proximate to the audio output port  244 . The speaker unit  234  is provided in or coupled to the first acoustic chamber  242 , for producing audible sounds. Further, the speaker unit  234  is disposed and fixed within the first acoustic chamber  242 . The speaker unit  234  comprises a front side adjacent to the first existing opening  232  for producing audible sounds and a backside separate from the front side for boosting sound resonance. The back chamber  238  is a second acoustic chamber  238  internal to the housing  240  and defined by a rear sidewall. The channel  236  is joined to and elongated between the first acoustic chamber  242  and the second acoustic chamber  238 , and is further disposed between the speaker unit  234  and the second acoustic chamber  238 , wherein a cross sectional area of the channel  236  (taken along a direction shown as line A) is smaller than a cross sectional area of the second acoustic chamber  238  (taken along the same first direction shown as line B), i.e. the channel  236  is narrower that the second acoustic chamber  238 . The channel  236  comprises a first communication opening joined to the first acoustic chamber  242  by connecting through a portion of the front side wall adjacent to the backside of the speaker unit  234  and a second communication opening joined to the second acoustic chamber  238  by connecting through the rear side wall. The channel  236  will cause a channel effect to decrease the low frequency component and caused a response drop at/around a standing wave frequency for the output signal Sout. To relief the channel effect, a porous material is filled inside at least a portion of the first acoustic chamber  242 , the second acoustic chamber  238 , and/or the channel  236 , for improving and extending bass performance and relieving the response drop around the standing wave frequency. Furthermore, it is noted that the second acoustic chamber  238  or the channel  236  is filled with a porous material PM partially or completely, i.e. bass extension material, such as N&#39;Bass™ dbass, carbon, powder, sponge and so on, wherein a fill rate of the porous material PM is determined according to actual application. 
       FIGS. 3A and 3B  show schematic diagrams illustrating various fill rates of the porous material PM disposed in the speaker module  230  of  FIG. 2 . In  FIG. 3A , a 50% fill rate of the porous material PM is shown. In the embodiment, the second acoustic chamber  238  is completely filled with the porous material PM, and no porous material PM is disposed in the channel  236 . In  FIG. 3B , a 100% fill rate of the porous material PM is shown. In the embodiment, the second acoustic chamber  238  and the channel  236  are completely filled with the porous material PM. 
       FIG. 4A  shows a frequency characteristic chart illustrating differences between a speaker module without porous material and a speaker module with the porous material PM according to an embodiment of this application.  FIG. 4B  shows an impendence characteristic chart illustrating the impendence characteristic corresponding to the frequency characteristic of  FIG. 4A . In  FIG. 4A , the curve S 1  represents the simulation result without porous material. Specifically, no porous material is disposed in the speaker module  230  of  FIG. 2 . The curve S 2  represents the simulation result with a 50% porous material, as shown in  FIG. 3A . The curve S 3  represents the simulation result with a 100% porous material, as shown in  FIG. 3B . It is noted that a response drop occurs at a standing wave frequency. Compared with the curve S 1 , the low frequency performance is extended/improved for the curve S 2  and the curve S 3 , as shown in label L 1 . Moreover, the response drop caused by the channel effect is at least relieved in the curve S 2  and even eliminated in the curve S 3 . By using the porous material PM in the speaker module  230 , bass performance is improved. Furthermore, impact caused by the standing wave effect in addition to the bass extension is also decreased. However, sound pressure level (SPL) around the resonance frequency is degraded. In  FIG. 4A , label L 2  shows that the resonance frequency has been degraded, and label L 3  shows the standing wave effect. In response to the degraded resonance frequency and the standing wave effect, two peaks f 0  and fs occur in the impendence chart of  FIG. 4B . 
       FIG. 5  shows a speaker amplifier  300  for increasing SPL around the resonance frequency according to an embodiment of this application. The speaker amplifier  300  receives an input signal Sin from a CPU (e.g.  110  of  FIG. 1 ) and provides an output signal Sout to a speaker unit  310  of a speaker module (e.g.  230  of  FIG. 2 ) for producing audible sound, wherein the CPU provides the input signal Sin according to a multi-media file stored in a portable device or from an external device. The speaker amplifier  300  comprises a compensation unit  320 , a gain unit  330 , an amplifier  340  and a feedback unit  350 . The feedback unit  350  is coupled to the speaker unit  310 , for receiving a feedback signal from the speaker unit  310  corresponding to the playing of a media file or impedance characteristic of the audio input, and for detecting an excursion of the speaker unit based on the feedback signal. Furthermore, the feedback unit  350  calculates the feedback signal and detects an impedance curve, a first peak, and/or a second peak of the calculated impedance curve. The first peak is detected and calculated in response to a resonance frequency of the impedance curve corresponding to the feedback signal, and the second peak is detected and calculated in response to a standing wave frequency of the impedance curve corresponding to the feedback signal. The first peak is caused by the porous material wherein resonance degradation is caused at/around a resonance frequency. The second peak is caused by the channel wherein the standing wave effect is caused at/around a standing wave frequency. Moreover, the standing wave effect is offset simultaneously by a response enhancement contributing to the porous material around the standing wave frequency. In some embodiment, the standing wave frequency is further shifted contributed to fill-in arrangement of the porous material. The compensation unit  320  is for receiving the audio input and outputting compensated signals accordingly by performing look-ahead based compensation according to the first peak and/or the second peak. Further, the compensation unit  320  compensates the input signal Sin according to a signal SF 2  from the feedback unit  350  and a signal SG 2  from the gain unit  330 , to provide a signal SC to the gain unit  330 . The gain unit  330  adjusts a gain value of the signal SC instantly according to a signal SF 1  from the feedback unit  350 , to provide a signal SG 1  to the amplifier  340 . The feedback unit  350  detects a deviation of an excursion of the speaker unit, and the gain unit  330  instantly adjust its gain value to correct the excursion of the speaker unit  310  based on the detected excursion of the speaker unit. The amplifier  340  amplifies the signal SG 1  to provide the output signal Sout to the speaker unit  310 . In  FIG. 5 , the feedback unit  350  generates the signals SF 1  and SF 2  according to a feedback signal FB corresponding to the output signal Sout from the speaker unit  310 .  FIG. 6  shows a processing method for the speaker amplifier  300  of  FIG. 5  according to an embodiment of this application. Referring to  FIG. 5  and  FIG. 6  together, first, in step S 410 , the predicted parameters of a model are determined by the compensation unit  320  and the gain unit  330  for the speaker unit  310 . Thus, the amplifier  340  provides the output signal Sout corresponding to the model to the speaker unit  310 . Next, in step S 420 , the feedback unit  350  receives the feedback signal FB corresponding to the model to calculate impedance, and then performs peak detection to obtain a peak f 0  and a peak fs for the calculated impedance, wherein the peak f 0  is detected in response to a resonance frequency of the feedback signal FB, and the peak fs is detected in response to a standing wave of the feedback signal FB, as shown in  FIG. 4B . Furthermore, the feedback unit  350  provides the signals SF 1  and SF 2  to the gain unit  330  and the compensation unit  320  according to the peaks f 0  and fs. Next, in step S 430 , the model is modified by the compensation unit  320  and the gain unit  330  according to the signals SF 1  and SF 2 . For example, the compensation unit  320  modifies the model by compensation in response to the signal SF 2 , and the gain unit  330  modifies the gain thereof to a proper gain in response to the signal SF 1  until the model is optimized for the speaker unit  310 . 
       FIG. 7  shows a speaker amplifier  500  for increasing SPL around the resonance frequency according to another embodiment of this application. The speaker amplifier  500  receives an input signal Sin from a CPU (e.g.  110  of  FIG. 1 ) and provides an output signal Sout to a speaker unit  510  of a speaker module (e.g.  230  of  FIG. 2 ) for playing audible sound, wherein the CPU provides the input signal Sin according to a multi-media file stored in a portable device or from an external device. The speaker amplifier  500  comprises a level detector  520 , a boost controller  522 , a non-linear compensator  530 , a gain controller  532 , a digital to analog converter (DAC)  534 , an amplifier  536 , a peak detector  540 , an impedance calculator  542  and an analog to digital converter (ADC)  546 . In  FIG. 7 , the level detector  520  detects a voltage level of the input signal Sin to provide a signal S 1 . According to the signal S 1 , the boost controller  522  provides a signal S 2  to control a gain of the amplifier  536 . Furthermore, the non-linear compensator  530  compensates the input signal Sin according to a signal S 4  from the gain controller  532 , to provide a signal S 3  to the gain unit  532 . The gain unit  532  modifies a gain of the signal S 3  according to a signal S 5  from the peak detector  540 , to provide a signal S 6  to the DAC  534 . The DAC  534  converts the signal S 6  to generate a signal S 7 . Next, the amplifier  536  amplifies the signal S 7  according to the signal S 2 , to provide the output signal Sout to the speaker unit  510 . Simultaneously, the amplifier  536  provides the output signal Sout to ADC  546 . The ADC  546  converts a feedback signal FB corresponding to the output signal Sout from the speaker unit  510 , to generate a signal S 9 . Next, the impedance calculator  542  calculates the impedance according to the signal S 9 , to obtain a signal S 8 . The peak detector  540  performs peak detection for the signal S 8 , so as to obtain a peak f 0  and a peak fs, wherein the peak f 0  is detected in response to a resonance frequency of the feedback signal FB, and the peak fs is detected in response to a standing wave of the feedback signal FB, as described above. Next, the peak detector  540  provides the signal S 5  to the gain unit  532  according to the peaks f 0  and fs. In response to the signal S 5 , the gain controller  532  modifies the gain thereof to a proper gain for the signal S 3 , and the gain controller  532  further provides the signal S 4  to the non-linear compensator  530 . In response to the signal S 4 , the non-linear compensator  530  compensates the input signal Sin to generate the signal S 3 . Thus, the degraded resonance frequency caused by the porous material PM is boosted back to the original SPL level. 
       FIG. 8  shows a method for operating a portable electronic device  100  of  FIG. 1 . Referring to  FIGS. 1-2, 5 and 8  together. The portable electronic device  100  having a speaker module  130  at least partially filled with a porous material, wherein the speaker module  130  is configured to produce audible sound and comprises a channel  236  for passing the audible sound. In step  810 , the CPU  110  requests to drive the speaker module  130  based on an audio input (Sin). In step  820 , the speaker amplifier  120  predicts a sound pressure level degradation around a resonance frequency caused by the porous material. Specifically, the feedback unit  350  receives a feedback signal and detects an excursion of the speaker module  130  during the driving of the speaker module  130  based on the feedback signal. Furthermore, the feedback unit  350  calculates the sound pressure level degradation based on the detected excursion. The sound pressure level degradation is indicated by a first peak corresponding to a resonance frequency and/or a second peak corresponding to a standing wave frequency, and the first and second peaks are caused by the porous material and the channel respectively or jointly. In step  830 , the speaker amplifier  120  compensates the audio input according to the sound pressure level degradation by performing look-ahead based inverse compensation. In step  840 , the speaker amplifier  120  produces an audio output to drive the speaker module  130  based on the compensating. In step  850 , the speaker amplifier  120  drives the speaker module to produce audible sounds based on the audio output. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.