Abstract:
An earphone includes a housing having a sound-emitting hole, a speaker mounted in the housing, and a passive radiator mounted in between the sound hole and the speaker driver and including a vibrating diaphragm main body and a weight embedded in the vibrating diaphragm main body or bonded to the top or bottom surface of the vibrating diaphragm main body. The mounting arrangement of the passive radiator optimizes the sound performance of the earphone. The weight of the passive radiator is firmly connected with the vibrating diaphragm main body so that severe vibration of the vibrating diaphragm main body does not cause disconnection of the weight.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to earphone technology, and more particularly, to an earphone having a passive radiator therein. 
         [0003]    2. Description of the Related Art 
         [0004]    Passive vibration diaphragm, also called as passive radiator, is normally mounted with a speaker in a cabinet to share the back cavity so that when the speaker converts electrical energy to sound waves, the air in the back cavity is compressed and transferred to the passive radiator, thereby indirectly driving the passive radiator to emit sound waves. Subject to the assistance of a passive radiator in a miniature speaker, the resonance effect of the back cavity is enhanced, and the overall performance of the sound field is optimized. 
         [0005]    However, the applications of conventional passive radiators are mostly limited to large speakers without being seen in earphones. The back cavity of an earphone is relatively smaller, so its resonance and bass drop sound effects are limited. Therefore, downsizing a passive radiator for installation in an earphone can effectively optimize the overall audio performance of the earphone and enhance its competitiveness on the market. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide an earphone, which enhances the resonance effect of the back cavity and optimizing audio performance. 
         [0007]    It is another object of the present invention to provide an earphone, which has a passive radiator built therein, enabling a weight in the passive radiator to be firmly connected with the vibrating diaphragm. 
         [0008]    To achieve these and other objects of the present invention, an earphone of the invention comprises a housing, a speaker, and a passive radiator. The housing comprises at least one sound hole. The speaker is mounted in the housing. The passive radiator comprises a vibrating diaphragm main body and a weight. The passive radiator is disposed between the sound hole and the speaker. The weight is embedded in the vibrating diaphragm main body. 
         [0009]    In an alternate form of the present invention, the earphone comprises a housing, a speaker, and a passive radiator, wherein the housing comprises at least one sound hole; the speaker is mounted in the housing; the passive radiator is disposed between the at least one sound hole and the speaker, comprising a vibrating diaphragm main body and a weight bonded to the top or bottom surface of the vibrating diaphragm main body. 
         [0010]    Subject to the mounting arrangement of the passive radiator, the sound performance of the earphone is optimized, and the weight of the passive radiator is firmly connected with the vibrating diaphragm main body. Even if the vibrating diaphragm main body vibrates heavily, the weight will not fall. 
         [0011]    Preferably, the vibrating diaphragm main body is made by molding. The vibrating diaphragm main body is configured to provide at least one through hole through which the material for making the weight, for example, polyurethane (PU) can be injected through the at least one through hole into the inside of the vibrating diaphragm main body. 
         [0012]    Further, the vibrating diaphragm main body composed of two composite layers and the weight can be separately made and then a press-forming technique is employed to have the weight be firmly embedded in between the two composite layers of the vibrating diaphragm main body. 
         [0013]    Other advantages and features of the present invention will be fully understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference signs denote like components of structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a sectional view of an earphone in accordance with a first embodiment of the present invention. 
           [0015]      FIG. 2  is a sectional view of the passive radiator of the earphone in accordance with the first embodiment of the present invention. 
           [0016]      FIG. 3  is a sectional view of a passive radiator for earphone in accordance with a second embodiment of the present invention. 
           [0017]      FIG. 4  is a sectional view of a passive radiator for earphone in accordance with a third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    For easily understanding the structural details and features of the present invention, an earphone  1  in accordance with a first embodiment is provided and illustrated in  FIGS. 1 and 2 . As illustrated, the earphone  1  comprises a housing  10 , a speaker  20 , and a passive radiator  30 . The structural details of these component parts and their relative relationship are explained hereinafter. 
         [0019]    Referring to  FIG. 1  again, the housing  10  is a hollow member comprised of a first outer shell  11 , a second outer shell  12  and an outer cover  13 . The second outer shell  12  is press-fitted onto the first outer shell  11 , comprising an annular groove  121  and an inner flange  122  located at one side thereof remote from the first outer shell  11 . The outer cover  13  is fastened to the annular groove  121  of the second outer shell  12 . 
         [0020]    The speaker  20  is fixedly mounted in the first outer shell  11  of the housing  10  to divide the internal space of the housing  10  into a first cavity  14  and a second cavity  15 . A first sound hole  141  is formed in the first outer shell  11  in communication with the first cavity  14  for the passing of the sound waves created by the speaker  20  to the user&#39;s ear. A second sound hole  151  is formed in the outer cover  13  in communication with the second cavity  15 . Further, an auxiliary sound hole  152  is formed in the second outer shell  12 . 
         [0021]    It is to be noted that, in this first embodiment, a first ventilation mesh  40 , a second ventilation mesh  41  and a third ventilation mesh  42  are respectively mounted in the sound hole  141 , the second sound hole  151  and the auxiliary sound hole  152  to adjust sound effects and to provide a waterproof effect; however, these ventilation meshes ( 40 ,  41  &amp;  42 ) are not requisite components. 
         [0022]    Referring to  FIG. 2  again, the passive radiator  30  comprises a vibrating diaphragm main body  31 , a weight  32  and a surround  33 , wherein the surround  33  surrounds and is connected with the peripheral edge of the vibrating diaphragm main body  31 ; the passive radiator  30  is fastened to the inner flange  122  of the second outer shell  12  through the surround  33  to shield the second sound hole  151 . The vibrating diaphragm main body  31  and the surround  33  are integrally molded in one piece. Further, the vibrating diaphragm main body  31  comprises an accommodation chamber  312 , and two pairs of through holes  311  bilaterally located in opposing top and bottom sides thereof in communication between the accommodation chamber  312  and the space outside the vibrating diaphragm main body  31  for the injection of a high density material to make the desired weight  32  and to have the weight  32  thus made be steadily embedded in the accommodation chamber  312  inside the vibrating diaphragm main body  31 . 
         [0023]    It is to be noted that the material for the vibrating diaphragm main body  31  can be mylar diaphragm; the material for the weight  32  can be selected from the group of polyurethanes (PUs) and silicon compounds. 
         [0024]    When the speaker  20  generates sound, it will compress the air in the second cavity  15  and force the air toward the passive radiator  30 , thereby indirectly driving the vibrating diaphragm main body  31  of the passive radiator  30  to vibrate and to produce sound. Because the weight  32  is steadily embedded in the vibrating diaphragm main body  31 , heavy vibration of the vibrating diaphragm main body  31  does not cause the weight  32  to fall out of the vibrating diaphragm main body  31  and to further affect the normal operation of the passive radiator  30 . Subject to the assistance of the passive radiator  30  and the tuning effect of the ventilation mesh  42  in the auxiliary sound hole  152 , the resonance effect of the second cavity  15  of the earphone  1  is greatly enhanced, and the earphone  1  is capable of getting great audio valance and strengthening the feeling of spatial sense, thereby effectively optimizing the overall sound performance. 
         [0025]    It is to be noted that the passive radiator  30  of the present invention has a simple structure, facilitating mass production. Further, the passive radiator  30  is not limited to earphone applications, it can also be used for headphone applications. 
         [0026]    Alternatively, the passive radiator  30  can be fixedly mounted in the inner wall of the outer cover  13  and covered over the second sound hole  151 , achieving the same effect of strengthening the feeling of spatial sense. Further, the amount of the through holes  311  is not limited to 4. Actually, the number of the through holes  311  can be increased, or reduced to 1, to meet actual requirements. 
         [0027]    Referring to  FIG. 3 , an earphone  1  in accordance with a second embodiment is shown. According to this second embodiment, the vibrating diaphragm main body  60  of the passive radiator  50  comprises a first composite layer  61  and a second composite layer  62  stacked together, two surrounds  71  and  72  respectively surrounding and connected with the first composite layer  61  and the second composite layer  62 , and a weight  80  embedded between the first composite layer  61  and the second composite layer  62 . This second embodiment achieves the same effect of prohibiting the weight  80  from falling out of the vibrating diaphragm main body  60 . Further, the weight  80  in this second embodiment can be a metal piece made by press forming; the first composite layer  61  and the second composite layer  62  can be prepared from different materials subject to actual requirements. Thus, this second embodiment widens the material selection range of the weight  80  and the vibrating diaphragm main body  60 . 
         [0028]    Further, injection molding technology can also be used for the fabrication of the passive radiator  50  in this second embodiment. During fabrication, put the weight  80  in the mold, and then mold the first composite layer  61  and the second composite layer  62  on the passive radiator  50 , either in a proper order or at the same time, using injection molding technology. Thus, the weight  80  will not fall out of the vibrating diaphragm main body  60  easily. Whether using the technique of press forming or injection molding, these two methods can easily allocate the weight  80 , and simplify mass fabrication of the passive radiator  50 . 
         [0029]    Referring to  FIG. 4 , an earphone in accordance with a third embodiment of the present invention is shown. This third embodiment is substantially similar to the aforesaid first embodiment with the exception that the weight  80  of the passive radiator  50  in this third embodiment is bonded to the top surface of the vibrating diaphragm main body  60 . However, this top mounting technique is not a limitation. Any person skilled in the art can bond the weight  80  to the bottom surface of the vibrating diaphragm main body  60  subject to actual requirements, achieving the same effect of firmly securing the weight  80  in place. 
         [0030]    Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.