Abstract:
A mobile phone and an acoustic box structure thereof are provided. The mobile phone includes a shell containing a printed circuit board (PCB) and a hidden antenna therein. The acoustic box structure is disposed between the PCB and the hidden antenna. The acoustic box structure includes a main body, a loudspeaker accommodated in the main body and a frame located between the PCB and the main body. Due to the design of the frame, a hermetic space is framed between the PCB and the main body, thereby preventing sound waves generated by the loudspeaker from leaking out via a gap between the main body and the PCB. Furthermore, the frame made of shockproof materials decreases the resonant transfer between the PCB and the loudspeaker. Consequently, the quality of the sound made by the mobile phone is improved.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to speaker sets for portable electronic devices, and more particularly to a speaker set for a mobile phone, which gives the mobile phone compact size and good sound quality. 
     2. Description of Related Art 
     Portable electronic devices, such as notebooks, CD players, MP3s and the like, have decreased both in size and weight over the past few years and are becoming ever more popular with travelers. This demand for smaller size with ever-increasing capability has required a tremendous effort to continually shrink many of the components contained within the device. 
     For a notebook computer, examples of component miniaturization are hard disk storage, circuitry, tracking devices, compact disc drives, speakers, and even connectors. The reduction in the size of many of these components has not been led to any serious problems, since technological advancements have allowed improved capability along with smaller size. However, portable electronic devices being designed today require multi-media features and provide the user with the same enjoyable experience as that experienced with conventional high quality desktop systems. Thus, the sounds emanating from a portable electronic device should provide as full a harmonic content as the original sounds. The production of low frequency sounds requires a large acoustic chamber for the movement of a large mass of air. As the device is reduced in size, the size of the acoustic chamber of the speaker set and the maximum power the speaker can handle are also accordingly reduced, resulting in both a reduction in loudness as well as a poorer overall quality of sound. However, increasing the device size to increase the size of the acoustic chamber for the speaker is very undesirable since it would strongly detract from the very characteristics that have helped to make these devices popular, namely size and weight. Thus the size of the device is at odds with high capability sounds of the speaker. 
     Consequently, inner spaces of the device which surround the speaker set are designed to communicate with the acoustic chamber so as to increase the size of the acoustic chamber but not increase the size of the device. However, the sound tends to leak from interstices formed between the components contained within the device and a housing of the device. The sounds leaked from the device interfere with the sounds dissipating from vent holes of the device, which decreases the overall sound quality of the device. 
     Therefore, a portable electronic device having a compact size and good sound quality is needed. 
     SUMMARY OF THE INVENTION 
     The present invention relates, in one respect, to a mobile phone having compact size and good sound quality, and in another aspect, to a speaker set for the mobile phone. According to a preferred embodiment of the present invention, the mobile phone includes a casing containing a printed circuit board and an antenna therein, and a speaker set disposed between the printed circuit board and the antenna. The speaker set includes a shell, a loudspeaker accommodated in the shell, and a hollow frame. The hollow frame is sandwiched between a base wall of the shell and the printed circuit board so as to form an acoustic chamber for the loudspeaker therebetween. 
     Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views: 
         FIG. 1  is an isometric view of a mobile phone according to a preferred embodiment of the present invention; 
         FIG. 2  is an assembled view of a speaker set and a printed circuit board and an antenna of the mobile phone of  FIG. 1 ; 
         FIG. 3  is an exploded, isometric view of the speaker set of  FIG. 2 ; 
         FIG. 4  is similar to  FIG. 3 , but viewed from another aspect thereof; 
         FIG. 5  is an exploded, isometric view of a shell of a speaker set according to a second embodiment of the present invention; 
         FIG. 6  is similar to  FIG. 5 , but viewed from another aspect thereof; and 
         FIG. 7  is an assembled view of a speaker set incorporating the shell of  FIGS. 5 and 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a mobile phone according to a preferred embodiment of the present invention is shown. The mobile phone includes a hollow casing  10  and a variety of elements enclosed therein. The casing  10  is substantially rectangular shaped in profile, and includes a keypad  11 , a display panel  12 , and a speaker section  13  respectively disposed at bottom, middle and top portions of the casing  10 . 
     Referring to  FIG. 2 , a speaker set  20  which is disposed in the speaker section  13  of the casing  10  includes a hollow shell  21 , a loudspeaker  22  accommodated in the shell  21 , and a hollow frame  23  sandwiched between the shell  21  and a printed circuit board  15  of the mobile phone. 
     Referring to  FIGS. 3 and 4 , the shell  21  of the speaker set  20  consists of two sub-shells, i.e., a first sub-shell  24  and a second sub-shell  25  covering the first sub-shell  24 . 
     The first sub-shell  24  includes a round chamber  245 , a first rectangular chamber  246 , a first channel  242  and a first pyramid chamber  243 . The round chamber  245  is formed between a base wall  244  of the first sub-shell  24  and a first annular wall  248  perpendicularly extending from a middle portion of the base wall  244 . The first annular wall  248  defines a cutout  248   a  therein, whilst a linear plate  242   a  and a serpentine plate  242   b  respectively extend from two sides of the cutout  248   a  towards a sidewall  247  of the first sub-shell  24 . The serpentine plate  242   b  has a rectangular portion  242   c  disposed adjacent to the round chamber  245  and a linear portion  242   d  parallel to the linear plate  242   a . The first rectangular chamber  246  is formed between the linear plate  242   a  and the rectangular portion  242   c  of the serpentine plate  242   b , and communicates with the round chamber  245  via the cutout  248   a . The first channel  242  is formed between the linear plate  242   a  and the linear portion  242   d  of the serpentine plate  242   b . Two slant plates  249  respectively extend from distal ends of the linear plate  242   a  and the serpentine plate  242   b  towards the sidewall  247  of the first sub-shell  24 . A distance between the slant plates  249  gradually increases from the distal ends of the linear plate  242   a  and the serpentine plate  242   b  towards the sidewall  247  of the first sub-shell  24 , so that the first pyramid chamber  243  is formed therebetween. 
     The second sub-shell  25  includes a round hole  255 , a second rectangular chamber  256 , a second channel  252  and a second pyramid chamber  253 . The second rectangular chamber  256 , the second channel  252  and the second pyramid chamber  253  have substantially similar configurations with the respective first rectangular chamber  246 , first channel  242  and first pyramid chamber  243  of the first sub-shell  24 . The round hole  255  extends through a base wall  254  of the second sub-shell  25 . A locking groove  255   a  is defined in the base wall  254  of the second sub-shell  25  and communicates with the round hole  255  at an end thereof. A second annular wall  258  extends from a front side of the base wall  254  of the second sub-shell  25 . The second annular wall  258  surrounds the round hole  255  and cooperates with the round hole  255  to accommodate the loudspeaker  22  therein. The loudspeaker  22  has hermetic seal with the second annular wall  258 , whilst the second annular wall  258  isolates an inner space thereof from the second rectangular chamber  256  so as to prevent sound waves generated by the loudspeaker  22  from leaking from the second annular wall  258  and the round hole  255  of the second sub-shell  25 . 
     Moreover, the second sub-shell  25  defines a plurality of vent holes  257   a  through a sidewall  257  thereof so as to communicate the second channel  252  with the surrounding environment. Alternatively, the vent holes  257   a  may be defined in the sidewall  247  of the first sub-shell  24 . The first sub-shell  24  is hermetically attached to the second sub-shell  25  via screws, adhesives or other appropriate means. A round chest is formed between the second annular wall  258  and the round chamber  245 , whilst a rectangular chest is formed between the first and second rectangular chambers  246 ,  256 , communicating with the round chest via the cutout  248   a . The round chest and the rectangular chest cooperatively form an irregular-shaped front acoustic chamber  241  for the loudspeaker  22 . A communicating channel is enclosed by the first and second channels  242 ,  252 , and a pyramid chest is enclosed by the first and second pyramid chambers  243 ,  253 . The front acoustic chamber  241 , the communicating channel and the pyramid chest cooperatively form a hermetic Helmholtz resonance chamber. A hermetic surrounding chamber  210  is formed between sidewalls of the shell  21  and outer walls of the Helmholtz resonance chamber. The sound waves generated by the loudspeaker  22  drive the air in the Helmholtz resonance chamber to resonate with the Helmholtz resonance chamber at a natural frequency thereof and then diffuse towards the surrounding environment via the vent holes  257   a.    
     The loudspeaker  22  defines a plurality of front tone holes  221  facing towards the first round chamber  245  of the first sub-shell  24  and a plurality of rear tone holes  222  opposite to the front tone holes  221 . The loudspeaker  22  electrically connects with the circuit board  15  so as to receive electrical signals from the circuit board  15  and convert the electric signals into acoustic signals. The acoustic signals drive a diaphragm (not shown) of the loudspeaker  22  to oscillate so as to generate sound waves. The sound waves are transmitted from the loudspeaker  22  via the front and rear tone holes  222 . The circuit board  15  and the speaker section  13  of the casing  10  respectively define a plurality of through holes  16 ,  14  corresponding to the rear tone holes  222  of the loudspeaker  22 . The loudspeaker  22  extends an ear  223  from a side thereof. The ear  223  is received in the locking groove  255   a  of the second sub-shell  25  so as to prevent the loudspeaker  22  from rotating in the round hole  255  of the second sub-shell  25 . 
     The hollow frame  23  is sandwiched between a rear side of the base wall  254  of the second sub-shell  25  and the circuit board  15 . The hollow frame  23  can be made of anti-vibration materials such as rubber, or glass fiber cloth and has a similar periphery configuration to the periphery configuration of the second sub-shell  25  when viewed from on top. The hollow frame  23  is preferably designed to satisfy a larger volume enclosed therein and not decrease the anti-vibration capability thereof. 
     A rear acoustic chamber  231  for the loudspeaker  22  is formed between a front side of the circuit board  15 , an inner wall of the hollow frame  23  and the rear side of the base wall  254  of the second sub-shell  25 . The sound waves in the rear acoustic chamber  231  diffuse towards the surrounding environment via the through holes  16 ,  14  of the circuit board  15  and the speaker section  13  of the casing  10 . Two layers of adhesive (not shown) are disposed between front and rear sides of the hollow frame  23  and respective portions of the front side of circuit board  15  and of the rear side of the base wall  254  of the second sub-shell  25  so that the hollow frame  23  has hermetic seal with the circuit board  15  and the second sub-shell  25 . Thus, the sound waves generated by the loudspeaker  22  can not leak from sides of the rear acoustic chamber  231 . Consequently, the sound waves in the rear acoustic chamber  231  diffuse towards the surrounding environment via the through holes  16 ,  14  of the circuit board  15  and the speaker section  13  of the casing  10  of the mobile phone. This prevents the sound waves in the front and rear acoustic chambers  241 ,  231  of the speaker set  20  from interfering with each other in the casing  10  of the mobile phone and thereby improves the quality of the sound made by the mobile phone. In addition, the hollow frame  23  weakens the vibration caused by the sound waves transferring towards the circuit board  15 , which prevents the quality of the sound from being impaired by the vibration. 
     Referring to  FIGS. 5 through 7 , a second embodiment of the present speaker set  30  is shown. The difference between the second embodiment from the first embodiment is: an opening  358  is defined through the base wall  354  of the second sub-shell  35  so as to communicate the rear acoustic chamber  331  with the surrounding chamber  310  of the shell  31 . The volume of the rear acoustic chamber  331  is therefore increased, which improves the low-frequency response of the loudspeaker  32  and accordingly improves the quality of the sound made by the mobile phone. Moreover, the opening  358  is disposed adjacent to the round hole  355  of the second sub-shell  35 , which decreases the distance between the rear tone holes  322  of the loudspeaker  32  and the surrounding chamber  310  of the shell  31 . The energy loss in dissipation of the sound waves is therefore decreased, which improves the loudness of the sound. 
     The present speaker set  20 / 30  is capable of being used in different kinds of portable electronic devices, such as personal digital assistants (PDAs), CD players, MP3s and MP4s, and more preferably in a mobile phone having a hidden antenna  17  therein. The antenna  17  is arranged at a front side of first-sub shell  24 / 34  and is spaced more than 7 mm from the circuit board  15  of the mobile phone so as to prevent electromagnetic interference between the circuit board  15  and the antenna  17 . The speaker set  20 / 30  is positioned in the space formed between the antenna  17  and the circuit board  15  so as to save space in the mobile phone. In addition, the hollow frame  23 / 33  prevents the quality of the sound from being impaired by the vibration between the loudspeaker  22 / 32  and the circuit board  15 . Consequently, the mobile phone is compact in size as well as having good sound quality. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of portions within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.