Patent Publication Number: US-10334354-B2

Title: Speaker box

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority benefit of Chinese Patent Application Ser. No. 201710539785.3 filed on Jul. 4, 2017, the entire content of which is incorporated herein by reference. 
     FIELD OF THE PRESENT DISCLOSURE 
     The present disclosure relates to electro-acoustic transducers, more particularly to a housing of a speaker box. 
     DESCRIPTION OF RELATED ART 
     With the arrival of mobile internet era, the number of intelligent mobile devices is on the increase. Among the many mobile devices, mobile phones are undoubtedly the most common, most portable mobile terminal devices. At present, the mobile phone functions are extremely diverse, one of which is high quality music function, therefore, the speaker boxes used to play sounds are applied to current smart mobile devices in large quantities. 
     The speaker box of relative art comprises a housing, a speaker unit accommodated in the housing, a through hole provided as penetrating the housing and a cover plate provided as covering the through hole, the speaker unit comprises a diaphragm for vibration and sound producing, the diaphragm and the housing are provided spaced apart to form a front sound cavity, the through hole and the diaphragm are provided rightly opposite each other, the speaker box also comprises a sound transmitting channel connecting the front sound cavity and the external environment, the front sound cavity and the sound channel form together the front cavity of the speaker box. 
     However, in the speaker box of related art, the inner walls of the front cavity are all rigid walls made up of rigid plastic material or metal material, the damp and the vibration amplitude of a rigid wall are small, its radiation energy is limited, and cannot effectively transmit the cavity energy in the front cavity out, thus it cannot absorb the energy of a specified frequency. Therefore, the rigid walls of the front cavity are prone to resonance because of the structure, which will then lead to sound distortion in the speaker box, affecting the acoustic performance of the speaker box. 
     Therefore it is necessary to provide an improved speaker box for overcoming the above-mentioned disadvantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the exemplary embodiment can be better understood with reference to the following drawing. The components in the drawing are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. 
         FIG. 1  is an isometric view of a speaker box in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 2  is a cross-sectional view of the speaker box, taken long line A-A in  FIG. 1 . 
         FIG. 3  shows a comparison of frequency response curves between the speaker box of the present disclosure (using an elastic cover plate) and a speaker box (using a rigid wall) of the related art. 
         FIG. 4  shows a comparison of total harmonic distortion curves of the speaker box (using an elastic cover plate) of the present disclosure and a speaker box (using a rigid wall) of the related art. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT 
     The present disclosure will hereinafter be described in detail with reference to an exemplary embodiments. To make the technical problems to be solved, technical solutions and beneficial effects of the present disclosure more apparent, the present disclosure is described in further detail together with the figure and the embodiment. It should be understood the specific embodiment described hereby is only to explain the disclosure, not intended to limit the disclosure. 
     Please refer to  FIGS. 1-2 , the present invention provides a speaker box  100  comprising a housing  1 , a speaker unit  2 , a through hole  3 , a sound transmitting channel  4  and an elastic cover plate  5 . 
     The speaker unit  2  is accommodated in the housing  1 . In this embodiment, the housing  1  comprises a lower plate  11  and an upper cover  12  which form jointly with the lower plate  11  an accommodating space  13 . The speaker unit  2  is fixed in the accommodating space  13 . 
     The speaker unit  2  comprises a diaphragm  21  for vibration and sound producing, the diaphragm  21  and the housing  1  are provided spaced apart to form a front sound cavity  6 . Specifically, the diaphragm  21  and the upper cover  12  form jointly the front sound cavity  6 . 
     The through hole  3  is provided as penetrating the housing  1  and is connected with the front sound cavity  6 . In the present embodiment, the through hole  3  is provided as penetrating the upper cover  12 . Preferably, the through hole  3  and the diaphragm  21  are provided rightly opposite each other. 
     The sound transmitting channel  4  is formed in the housing  1 , specifically, the sound transmitting channel  4  is formed on the upper cover  12 . The sound transmitting channel  4  connects the front sound cavity  6  with the outside, by which a side sound producing structure is formed. That is to say, in this embodiment, the diaphragm  21  (the speaker unit  2 ) divides accommodating space  13  into a front cavity  131  and the back cavity  132 , in which, the front cavity  131  comprises the front sound cavity  6  and the sound transmitting channel  4 , which are used for transmitting sound; the back cavity  132  has the function of improving the low frequency acoustic performance of the speaker box  100 . 
     That is, the through hole  3  is provided at the position on the housing  1  corresponding to the front cavity  131 , which penetrates the housing  1  and connects the front cavity  131  with the outside. 
     The elastic cover plate  5  is provided in the front cavity  131  and fixed at the side of the housing  1  close to the diaphragm  21  and covers the through hole  3 , and it is used for absorbing the vibration of a particular resonant frequency. The Young&#39;s modulus or strength the elastic cover plate  5  is smaller than that of the housing  1  (preferably, the upper cover  12 ). 
     In this invention, the elastic cover plate  5  will replace the rigid wall of related art, and the elastic cover plate  5  has a resonant frequency, when, through design, the resonant frequency of the elastic cover plate is adjusted to a certain frequency, the elastic cover plate  5  will produce strong vibration near the resonance frequency, when the speaker box  100  produces sounds and the speaker unit  2  vibrates, the air in the front cavity will be compressed and energy will be produced, this energy will drive the elastic cover plate  5  to vibrate, thus the energy in the front cavity will be consumed, preferably, the elastic cover plate  5  vibrates at the resonant frequency, under which condition the vibration intensity will reach the maximum, thus more energy can be consumed; and thus the aim of absorbing energy near the specific frequency can be achieved; in addition, by replacing the rigid wall with the elastic cover plate  5 , the medium density in the front cavity  131  can be transmitted to the outside of the front cavity  131 , thereby reducing the resonance phenomenon of the speaker box  100  and improving distortion. 
     Specifically, the purposes mentioned above are achieved by designing the material, area, shape and thickness of the elastic cover plate  5 . In this embodiment, the elastic cover plate  5  is made of material with low Young&#39;s modulus or strength, at least below that of the upper cover  12 , such as TPU or MCP or silica gel. Then they are fixedly connected by double-shot molding or hot pressing or pasting or ultrasonic welding, forming part of the structure of the front cavity  131 , absorbing the energy in the front cavity  131  of the speaker box  100  near resonant peak, and achieving the purpose of decreasing resonance peak, reducing distortion and improving the acoustic performance of the speaker box  100 . The elastic cover plate  5  can be designed and adjusted according to the range of the resonant frequency that needs to be absorbed. The specific resonant frequency is just the set range of resonance frequency that needs to be absorbed. 
     Please refer to  FIG. 3 , a frequency response curve of the elastic cover plate of the speaker box of the invention and a rigid wall of the related art. As shown in  FIG. 3 , in the frequency response curve of the elastic cover plate  5  the speaker box  100  of the invention, the resonance peak decreases obviously, meaning the resonance phenomenon is reduced. 
     Please refer to  FIG. 4 , a total harmonic distortion curve of the elastic cover plate of the speaker box of the invention and a rigid wall of the related art. As shown in  FIG. 4 , in the total harmonic distortion curve of the elastic cover plate  5  the speaker box  100  of the invention, the distortion spike decreases obviously, meaning distortion is reduced. 
     In the speaker box  100  of the invention, the resonance frequency of the elastic cover plate  5  is 500-15000 Hz; 
     When the resonance frequency of the elastic cover plate  5  is 500-1500 Hz, the distortion near the low frequency resonance frequency f0 of the speaker box  100  can be reduced, the second time distortion near the corresponding f0/2 can be reduced, the third time distortion near the f0/3 can be reduced, etc.; 
     When the resonance frequency of the elastic cover plate  5  is 1500-3000 Hz, the medium frequency distortion near 2000 Hz of the speaker box  100  can be reduced, the second time distortion near the corresponding 1000 Hz can be reduced, the third time distortion near 667 Hz can be reduced, etc.; 
     When the resonance frequency of the elastic cover plate  5  is 3000-9000 Hz, the distortion near the high frequency resonance peak Fh of the speaker box  100  can be reduced, the second time distortion near the corresponding Fh/2 can be reduced, the third time distortion near Fh/3 can be reduced, etc.; 
     When the resonance frequency of the elastic cover plate  5  is 9000-15000 Hz, the distortion near the high frequency 12000 Hz of the speaker box  100  can be reduced, the second time distortion near the corresponding 6000 Hz can be reduced, the third time distortion near 4000 Hz can be reduced, etc. 
     Please refer to  FIG. 4 , a frequency response curve of the acoustic performance test data of the speaker box of the present invention. According to the experimental data and effects, in this embodiment, the elastic cover plate  5  preferably absorbs vibration at a resonance frequency of 3000˜9000 Hz, under this condition, the distortion reducing effect of the speaker box  100  is better. 
     In the embodiment, the elastic cover plate  5  is fixed at the upper cover  12  and is provided rightly opposite the diaphragm  21 . Specifically, the elastic cover plate  5  and the upper cover  12  of the housing  1  are fixedly connected by double-shot molding or hot pressing or pasting or ultrasonic welding. Of course, the methods to fix the two are not limited to this. 
     To make sure that the through hole  3  can leak sound pressure stably, a gap is provided between the elastic cover plate  5  and the upper cover  12  of the housing  1 , forming a pressure leaking space. 
     For example, a groove  7  is formed with the surface of the upper plate  12  opposite the diaphragm  21  sinking toward the direction far from the diaphragm  21 , the groove  7  is connected with the through hole  3 , the elastic cover plate  5  is fixed on the surface of the upper plate  12  facing the diaphragm  21  and covers the groove  7 . The groove  7  forms thus the gap structure. 
     It needs to be pointed out that, the elastic cover plate  5  is provided to absorb the specific resonance frequency energy of the front cavity  131 , therefore, the structure of the elastic cover plate  5  is not limited to be provided as the above structure, its position is not limited to the above position, either. It can also be provided in the sound transmitting channel  4 . 
     Compared with the related art, the speaker box of the invention provides an elastic cover plate with Young&#39;s modulus or strength smaller than that of the housing in the front cavity, to absorb the vibration at a specific resonance frequency, thus weakening the resonance effect of the speaker box, reducing its distortion, and thus improving the acoustic performance of the speaker box. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present exemplary 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 where the appended claims are expressed.