Patent Publication Number: US-9843857-B2

Title: Speaker box

Description:
FIELD OF THE INVENTION 
     The present invention relates to speakers for converting electrical signals into sound waves, and more particularly related to a vibration balanced speaker box. 
     DESCRIPTION OF RELATED ART 
     In the mobile Internet era, number of smart mobile devices is on the rise. Among all kinds of mobile devices, mobile phone is undoubtedly the most common and most portable mobile terminal device. Mobile phone&#39;s functions are very diversified at present. One of them is high-quality music feature. The speaker of the mobile phone is the one of the prerequisite conditions to realize the high quality music feature. In the mobile phones on the market at present, the miniature electromagnetic speaker is commonly used for realizing music playing function. 
     Normally, the speaker includes a frame as the housing, a magnet system fixed in the frame and a vibration system which interacts with the magnetic system and vibrates. The magnetic system typically includes a yoke, a magnet fixed at a center of the yoke and a magnetic gap formed between the yoke and the magnet. The vibration system typically includes a voice coil extending into the magnetic gap and a diaphragm connected to the voice coil. When the voice coil receives the electrical signals containing audio signals, it interacts with the magnetic field of the magnet system, and generates Ampere force. Stressed under the Ampere force, the voice coil realizes reciprocating vibration, thus resulting in the vibration of the diaphragm, and producing acoustic radiation. Along with the development of intellectualized mobile phones, the media content on mobile phone is increased more and more. The user&#39;s requirement on sound quality of media is also increased. The user hopes the sound generator in the mobile phone can provide better low frequency response. This requires the sound generator to have a relatively larger back cavity. This leads to the structure that the sound generator is packed in the cavity. This structure is generally called as speaker box. 
     The speaker box usually requires a sounding hole to transmit the sound generated from the sound generator element to the outside. Generally, the position of the sounding hole is biased in the speaker box relative to the sound generator element, which is that the position of the sounding hole is biased relative to the center of the sound generator element. In this way, the vibration system of the sound generator element is divided into the near-end which is near the sounding hole, and the far-end which is farther the sounding hole. When the vibration system vibrates, the air around the near-end of the vibration system is relatively easier to pass through the sounding hole; while the air around the far-end is comparatively more difficult to pass through the sounding hole. It can be simply understood that the near-end near the sounding hole is easier to vibrate; while the far-end is relatively difficult to vibrate. This leads to an imbalance vibration of the vibration system between the near-end and the far-end, and leads to a series of problems, such as infidelity. 
     Therefore, it is necessary to provide an improved speaker box to solve the problems mentioned above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the embodiment 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 disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is an isometric view of a speaker box in accordance with an exemplary embodiment of the present disclosure; 
         FIG. 2  is an exploded schematic view of the speaker box in  FIG. 1 ; 
         FIG. 3  is a cutting view of the speaker box in  FIG. 1 ; and 
         FIG. 4  is a cross-sectional view of the speaker box in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT 
     The present invention will hereinafter be described in detail with reference to an exemplary embodiment. To make the technical problems to be solved, technical solutions and beneficial effects of present disclosure more apparent, the present disclosure is described in further detail together with the figures and the embodiment. It should be understood the specific embodiment described hereby is only to explain this disclosure, not intended to limit this disclosure. 
     As shown in  FIGS. 1-4 , a speaker box  10  disclosed in an exemplary embodiment of the present disclosure includes a housing  1  which has a receiving space  20  and a sound generator inside the housing  1 . The housing  1  includes an upper housing  11  and a lower housing  12 . The upper housing  11  and lower housing  12  form the receiving space  20 . The upper housing  11  is provided with a side wall  110  and an upper wall  112  extending along a horizontal direction. The receiving space  20  on the side wall  110  is used to export the sound emitted by the sound generator  13  to the sounding hole  111  outside the speaker box  10 . The upper wall includes an inner surface  1120  facing to the receiving space  20 . The sound generator  13  is connected to an external circuit through a conductive element  14 . In this embodiment, the conducting element  14  is a flexible circuit board. In order to facilitate the conducting element  14  to connect to the outside, the lower housing  12  is provided with a notch  121  at the position corresponding to the conducting element  14 . The conducting element  14  is connected to the outside through the notch  121 . 
     The sound generator  13  further comprises a magnetic system and a vibration system which is interactive to the magnetic system. The magnetic system includes a lower plate  131  fixed to a main magnet  132  at a central position of the lower plate  131 , and a secondary magnet fixed to the lower plate  131  and kept a space to the main magnet  132 . Thereby, a magnetic gap is accordingly formed between the main magnet  132  and secondary magnet  133 . The vibration system includes a voice coil  134  suspended in the magnetic gap and a diaphragm  130  connected to the voice coil  134  for vibration sounding. The diaphragm  130  further includes a dome  135  located at a central position thereof and a periphery  136  surrounding and supporting the dome  135 . 
     With the sounding hole  111  as a reference, the dome  135  is defined that it includes a near-end  135   a  which is near the sounding hole  111 , and a far-end  135   b  which is farther the sounding hole  111 . The dome  135  includes an upper surface  1351  facing to the inner wall  1120 . A distance from the inner surface  1120  to the upper surface  1351  of the near-end  135   a  is shorter than the distance from the inner surface  1120  to the upper surface  1351  of the far-end  135   b . The voice coil  134  is disposed under the dome  135  and supports the near-end  135   a  and the far-end  135   b  of the dome  135 . The voice coil drives the near-end and the far-end at the same time. A vibration direction of the diaphragm  130  is perpendicular to an output direction of the sound. And the vibration direction of the diaphragm  130  is perpendicular to an output direction of the upper wall  1120  of the housing  1 . 
     As the resistance received by the far-end  135   b  during vibration is greater than the resistance of the near-end  135   a , the vibration is imbalanced. The weight of the far-end  135   b  is set to be smaller than the weight of the near-end  135   a . The compliance of the near-end  135   a  of the dome is less than the compliance of the far-end  135   b . The acoustic resistance of the far-end  135   b  of the dome  135  can be made smaller, so as to balance the vibration of the diaphragm  130  and reduce infidelity. Optionally, the weight at the dome  135  is increased gradually from the far-end  135   b  to the near-end  135   a.    
     In addition, a thickness of the near-end  135   a  is set to be greater than a thickness of the far-end  135   b , and the thickness can be increased gradually from the far-end  135   b  to the near-end  135   a . The near-end  135   a  and the far-end  135   b  can also be made of different materials. The material density of the near-end  135   a  can be bigger than the material density of the far-end  135   b.    
     The present disclosure discloses a speaker box, by setting the different property or different material of the near-end and far-end of the dome, such as thickness or material, to increase the compliance of the far-end, reduce acoustic impedance, balance diaphragm vibration and reduce infidelity. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiment have been set forth in the foregoing description, together with details of the structures and functions of the embodiment, 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 invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.