Abstract:
An exemplary portable electronic device includes a front cover having a display panel mounted thereon, a rear cover connected to the front cover, and two speakers received between the front cover and the rear cover. The rear cover defines two recesses in two side portions thereof. Each side portion of the rear cover defines sound emission holes communicating with the recess. Each speaker is located adjacent to and faces corresponding sound emission holes. Sound produced by each speaker transmits through the corresponding sound emission holes along a vertical direction perpendicular to the display panel, and spreads to the outside environment through an adjacent recess.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is a continuation-in-part (CIP) application of patent application Ser. No. 12/973,802, entitled “PORTABLE ELECTRONIC DEVICE HAVING OBLIQUE SOUND OUTPUT ARRANGEMENT,” and filed on Dec. 20, 2010. The disclosure of the parent application is incorporated herein by reference in its entirety. 
     
    
       [0002]    BACKGROUND 
         [0003]    1. Technical Field 
         [0004]    The disclosure generally relates to portable electronic devices, and more particularly to a portable electronic device configured to provide optimum sound output for one or more speakers thereof. 
         [0005]    2. Description of Related Art 
         [0006]    A portable electronic device, such as a mobile phone, a tablet computer, a handheld game console, a personal digital assistant (PDA) or an MP4 (MPEG audio layer 4) player, usually has a built-in speaker, for users to listen to callers, listen to music, or play games for example. To obtain a high-quality sound effect, sound emission holes for the speaker are desired to be defined in a front side of the portable electronic device. 
         [0007]    However, a display panel and some operating keys are usually arranged at the front side of the portable electronic device. The sound emission holes defined in the front side of the portable electronic device limit the area available for the display panel and the operating keys. To avoid this problem, sound emission holes of some portable electronic devices are instead defined in peripheral walls of the portable electronic device. A commonly used portable electronic device includes a shell, and two speakers arranged in the shell. The two speakers are located at two adjacent corners of the shell, respectively. Two sets of sound emission holes are defined in a peripheral wall of the portable electronic device, adjacent to two corners of the portable electronic device. Each set of sound emission holes is located adjacent to a corresponding speaker. However, the sound emission holes are disposed at a lateral side of the speaker, not a front (sound output) side of the speaker. Thus the intermediate frequency and high frequency ranges of the sound output from the portable electronic device are weakened, and users cannot fully appreciate or enjoy the sound when they listen to callers or music or play games. Further, the sound emission holes defined in the peripheral wall may be covered by a user&#39;s hands, thereby reducing the sound pressure. 
         [0008]    What is needed, therefore, is a means to overcome the described limitations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the views. 
           [0010]      FIG. 1  is an isometric, assembled view of a portable electronic device in accordance with a first embodiment of the present disclosure, showing the portable electronic device facing down. 
           [0011]      FIG. 2  is an exploded view of the portable electronic device of  FIG. 1 , but showing the portable electronic device facing up, and omitting a plurality of components inside a shell of the portable electronic device. 
           [0012]      FIG. 3  is a plan view of the portable electronic device of  FIG. 1 , showing a rear of the portable electronic device. 
           [0013]      FIG. 4  is a side plan view of the portable electronic device of  FIG. 1 , but showing the portable electronic device facing up and resting on a horizontal surface. 
           [0014]      FIG. 5  is an enlarged view of a circled portion V of  FIG. 4 . 
           [0015]      FIG. 6  is similar to  FIG. 4 , showing a portable electronic device in accordance with a second embodiment of the present disclosure facing up and resting on a horizontal surface. 
           [0016]      FIG. 7  is an enlarged view of a circled part VII of  FIG. 6 . 
           [0017]      FIG. 8  is similar to  FIG. 3 , showing a rear of a portable electronic device in accordance with a third embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Referring to  FIGS. 1-2 , a portable electronic device  100  according to a first embodiment of the present disclosure is shown. The portable electronic device  100  can be a mobile phone, a tablet computer, a handheld game console, a PDA, an MP4 player, or another kind of handheld electronic device. 
         [0019]    The portable electronic device  100  includes a generally flat shell  10  in which components of the portable electronic device  100 , such as a circuit board, a central processing unit, a battery, a multimedia module and two speakers  20 , are received. The shell  10  includes a front cover  11 , and a rear cover  12  connected to the front cover  11 . The front cover  11  and the rear cover  12  cooperatively define a receiving space therebetween for receiving the components of the portable electronic device  100 . 
         [0020]    The front cover  11  includes a substantially rectangular front plate  112 , and a sidewall  113  extending from a peripheral edge of the front plate  112  towards the rear cover  12 . The portable electronic device  100  has a display panel  111  fixed to a rear side of the front plate  112  and exposed from a window (not labeled) defined in a central area of the front plate  112 . The display panel  111  has a substantially uniform thickness, and a front face of the display panel  111  is substantially coplanar with a front face of the front plate  112 . 
         [0021]    Referring also to  FIG. 3 , the rear cover  12  includes a substantially rectangular rear plate  124 , and a sidewall  125  extending from a peripheral edge of the rear plate  124  towards the front cover  11 . The rear plate  124  has a central flat portion  126  substantially parallel to the display panel  111 , and two angled portions  121  at two opposite sides of the flat portion  126 . The two angled portions  121  extend frontward and outwardly from two opposite sides of the flat portion  126  (see  FIG. 4 ), respectively. Each angled portion  121  is located between the flat portion  126  and a corresponding short side of the sidewall  125  of the rear cover  12 . The angled portion  121  defines a set of sound emission holes  122  therein. Each angled portion  121  may have a planar or curved outer surface. In the present embodiment, each angled portion  121  has a planar outer surface. A set of sound emission holes  122  is located in approximately a center of each angled portion  121 , halfway along a longitudinal axis of the angled portion  121 . In this embodiment, the longitudinal axis of the angled portion  121  is parallel to the corresponding short side of the sidewall  125  of the portable electronic device  100 . The sound emission holes  122  of the angled portion  121  are arranged in a rectangular array (or matrix). Alternatively, the sound emission holes  122  of the angled portion  121  may be arranged in a circular array. 
         [0022]    Referring to  FIG. 4 , when the shell  10  is disposed on a horizontal surface  30  with the display panel  111  facing up, a wedge-shaped gap  31  is defined between each angled portion  121  and the horizontal surface  30 . Sound from the two sets of sound emission holes  122  can travel through the wedge-shaped gaps  31  to the ambient environment, whereby the sound volume and quality provided by the portable electronic device  100  is enhanced. 
         [0023]    Each angled portion  121  of the rear plate  124  of the rear cover  12  forms a substantially annular wall  127  on an internal surface thereof, corresponding to and substantially surrounding the respective set of sound emission holes  122 . The angled portion  121  and the annular wall  127  cooperatively define a sound chamber  123  therebetween for receiving a corresponding speaker  20 . The sound chamber  123  is substantially cylindrical (or disk-shaped). Each set of sound emission holes  122  is defined in a region of the angled portion  121 , which region can be considered to be surrounded by the annular wall  127 . A ratio of an area of the set of sound emission holes  122  to an area of the region surrounded by the annular wall  127  is not less than 20%. 
         [0024]    The two speakers  20  are arranged in the shell  10 , and are located corresponding to the sets of sound emission holes  122  of the two angled portions  121 . In particular, each speaker  20  is received in a corresponding sound chamber  123 , with a sound output side of the speaker  20  (i.e., a side of the speaker  20  at which the diaphragm of the speaker  20  is located) facing the corresponding set of sound emission holes  122  of the shell  10 . 
         [0025]    Referring also to  FIG. 5 , when each speaker  20  is in operation, sound emitted by the speaker  20  travels along the corresponding set of sound emission holes  122 , through the corresponding wedge-shaped gap  31 , and then to the ambient environment. An angle formed between a direction of maximum sound intensity of the speaker (indicated by the arrows in  FIG. 4 , i.e., an axial direction of each sound emission hole) and the front face of the display panel  111  is an acute angle. In other words, the direction of maximum sound intensity is neither parallel nor perpendicular to a plane of the display panel  111 . Preferably, the angle between the direction of maximum sound intensity and the plane of the display panel  111  is selected to be in the range of from 30° to 60°. 
         [0026]    The shell  10  has a symmetrical structure. The two angled portions  121  of the rear plate  124  are symmetrically arranged at the rear side of the shell  10 . Alternatively, the rear plate  124  can provide four angled portions  121  at the rear side of the shell  10 , with all four angled portions  121  adjacent to the sidewall  125  of the rear cover  12 . Each angled portion  121  defines a set of sound emission holes  122  therein. Accordingly, four speakers  20  are provided in the shell  10 , with each speaker  20  located corresponding to a respective set of sound emission holes  122 . 
         [0027]    In the portable electronic device  100 , each set of sound emission holes  122  is defined in a corresponding angled portion  121  of the rear plate  124  of the shell  10 . Thereby, the sound output side of the corresponding speaker  20  can be arranged directly adjacent to the sound emission holes  122 . Compared with a conventional portable electronic device in which sound emission holes are disposed at a lateral side of a speaker, the portable electronic device  100  has significantly strengthened intermediate frequency and high frequency ranges (particularly 5 kHz to 20 kHz) of output sound. Therefore, the portable electronic device  100  permits its users to fully appreciate and enjoy the sound when they listen to a caller or music or play games. Further, the portable electronic device  100  helps to prevent the sound emission holes  122  from being covered by a user&#39;s hands, while still allowing convenient placement and arrangement of the display panel  111  and operating keys thereof. That is, the portable electronic device  100  avoids inadvertent and unwanted reduction of sound pressure. 
         [0028]    Referring to  FIGS. 6-7 , a portable electronic device  100   a  in accordance with a second embodiment of the present disclosure is shown. Different from the portable electronic device  100  of the first embodiment, the portable electronic device  100   a  has two external recesses  130   a  defined in two side portions of a rear cover  12   a  thereof, respectively. Each recess  130   a  has an inner face  140   a,  which is parallel to a rear face  142   a  of a flat portion  126   a  of the rear cover  12   a,  and is also parallel to a display panel  111   a  of the portable electronic device  100   a.  The rear face  142   a  of the rear cover  12   a  is disposed on a horizontal surface  30   a,  with the inner face  140   a  of each recess  130   a  being spaced from the horizontal surface  30   a.    
         [0029]    A set of sound emission holes  122   a  is defined in the inner face  140   a  of each recess  130   a,  i.e., in the corresponding side portion of the rear cover  12   a.  Each of the sound emission holes  122   a  extends along a vertical direction, perpendicular to the inner face  140   a  of the recess  130   a.  A speaker  20   a  is disposed adjacent to inner ends of the sound emission holes  122   a.  A substantially annular wall is formed on a front face of the end portion of the rear cover  12   a  at the sound emission holes  122   a,  and surrounds the speaker  20   a.  In  FIGS. 6-7 , only outlines of the substantially annular wall are shown, with broken lines. The speaker  20   a  has a sound output side facing the sound emission holes  122   a,  so that the sound generated from the speaker  20   a  can spread along vertical directions to the corresponding recess  130   a  through the sound emission holes  122   a.  The sound in the recess  130   a  is reflected by the horizontal surface  30   a,  and by a lateral face of the recess  130   a  which interconnects the inner face  140   a  of the recess  130   a  and the rear face  142   a  of the rear cover  12   a,  and propagates to the ambient environment. A direction of a maximum sound intensity of the speaker  20   a  is parallel to the vertical direction. 
         [0030]    The other elements (such as a front plate  112   a  of a front cover) of the portable electronic device  100   a  not mentioned above are substantially the same as those of the portable electronic device  100  of the first embodiment. 
         [0031]      FIG. 8  shows a portable electronic device  100   b  in accordance with a third embodiment of the present disclosure. Different from the portable electronic device  100   a  of the second embodiment, the portable electronic device  100   b  has two reflection plates  132   b  formed in two recesses  130   b,  respectively, to facilitate reflection of sound to the ambient environment. The two reflection plates  132   b  are located at two opposite sides of a flat portion  126   b,  with each reflection plate  132   b  adjacent to a corresponding set of sound emission holes  122   b.  Each reflection plate  132   b  extends rearward from an inner face (not labeled) of the corresponding recess  130   b,  in a direction generally away from the sound emission holes  122   b.  The reflection plate  130   b  is curved, and partially surrounds the set of sound emission holes  122   b,  with a concave side of the reflection plate  130   b  facing the set of sound emission holes  122   b.    
         [0032]    It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.