Patent Publication Number: US-8983111-B2

Title: Speaker

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to the art of speakers and, particularly to a speaker having multi-magnetic circuits. 
     DESCRIPTION OF RELATED ART 
     With the rapid development of technologies, the design of electronic devices, such as cellular phones, PDAs (personal digital assistants), and so on, is being driven by the marketplace towards providing more and more multimedia functions. At the same time, consumer&#39;s demand has continued to push a dramatic reduction in the size of the electronic devices. 
     Typically, most electronic devices today include a micro-speaker with multi-magnetic circuits. The micro-speaker related to the present disclosure includes a case defining a cavity, at least one magnetic circuit unit with two magnetic gaps received in the cavity, at least two vibrating units attached on the case. Each of the vibrating units includes a voice coil partially suspended in the magnetic gap, a diaphragm directly or indirectly connected to the voice coil. The voice coil of the vibrating unit is electrically connected to an external circuit via a conductive wire of the voice coil for driving the diaphragm to vibrate along a vibrating direction. 
     In order to improve the performance of the micro-speaker, the micro-speaker typically includes dual-magnetic-circuit structure defining two magnetic gaps, and two voice coils corresponding to the magnetic gaps respectively. However, during the vibration of the vibrating units, a distance between the two the voice coils is too long, which directly leads the conductive wire to be fractured and leads the lifespan of the micro-speaker to be shortened. 
     Therefore, it is desirable to provide an improved speaker which can overcome the above-mentioned problems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a speaker in accordance with an exemplary embodiment of the present invention; 
         FIG. 2  is a cross-sectional view of the speaker taken along line A-A in  FIG. 1 ; 
         FIG. 3  is an exploded view of the speaker in  FIG. 1 ; 
         FIG. 4  is an isometric view of the speaker in  FIG. 1 , with a terminal board thereof being removed away; and 
         FIG. 5  is an isometric view of a terminal board of the speaker in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     A speaker in accordance with an exemplary embodiment of the present invention is used for converting audio electrical signals to audible sounds. The speaker includes a box with a sound hole, a magnetic circuit including at least two magnetic gaps, at least two vibrating units corresponding to the magnetic gaps, respectively, at least a pair of welding pads embedded in the box to electrically connecting with the vibrating units, a terminal board engaged with the box and contacting the welding pads for conducting electrical signals to the vibrating units. 
     Referring to  FIGS. 1-3 , a speaker  100 , in accordance with an exemplary embodiment of the present disclosure, includes a magnetic circuit unit  21 , a first vibrating unit  22 , a second vibrating unit  23 , a box  10  including a cover  11 , a frame  12  and a case  13 . The box forms a cavity for accommodating the magnetic circuit unit  21  and the two vibrating units  22 ,  23  therein. The speaker  100  further includes a pair of first pads  24  and a pair of second pads  25  respectively mounted on the cover  11  and the frame  12  for electrically connecting with the first vibrating unit  22  and the second vibrating unit  23 . In addition, the speaker  100  includes a terminal board  30  mounted on an outer surface of the box  10 . 
     The cover  11  includes an upper end  110  coupled to the first vibrating unit  22 , and a lower end  114  opposite to the upper end  110  for being coupled to a upper surface  121  of the frame  12 , whereby, a first receiving space  113  is formed by the cover  11  together with the frame  12 , for receiving the magnetic circuit unit  21  and the first vibrating unit  22  therein. Furthermore, the frame  12  is annular, and further includes a connecting surface  124  opposite to the upper surface  121  attached to the case  13 . The case  13  is approximately oblong bowl-shaped, and includes a lid  132 , a bucket  131 . A second receiving space  133  is accordingly formed by the lid  132  cooperatively with the bucket  131 . The lid  132  includes a plurality of sound holes  1321 . The second vibrating unit  23  is received in the second receiving space  133  of the case  13 . 
     The magnetic circuit unit  21  includes a yoke  211 , an annular magnet  212  positioned in the yoke  211 , and a T-shaped member  213  attached to a top surface of the magnet  212 . The magnetic circuit unit  21  is used for providing substantially closed magnetic field. The yoke  211  has a receiving room  211   a  bounded by a sidewall  211   b  and a bottom  211   c . The magnet  212  is received in the receiving room  211   a . The bottom  211   c  of the yoke  211  defines a central hole  211   d . The magnet  212  forms a channel  212   a  corresponding to the central hole  211   d  of the yoke. The T-shaped member  213  includes a base  213   a  and a central pole  213   b  extending from the center of the base  213   a.  While assembled, the base  213   a  of the T-shaped member  213  attached to the top surface of the annular magnet  212  with the central pole  213   b  accommodated in the channel  212   a  of the annular magnet  212 . Furthermore, a diameter of the base  213   a  of the T-shaped member  213  is equal to an outer diameter of the annular magnet  212 . A diameter of the central hole of the yoke  211  is equal to the diameter of the channel  212   a  of the annular magnet  212 , and a diameter of the central pole  213   b  is smaller than the diameter of the channel  212   a . While assembled, a first magnetic gap  214  is formed between the central pole  213   b  of the T-shaped member  213  and the inner side of the annular magnet  212 , and a second magnetic gap  215  is formed between the sidewall  211   b  of the yoke  211  and the outer side of the annular magnet  212 . 
     The first vibrating unit  22  includes a first diaphragm  221  and a first voice coil  222  directly or indirectly coupled to the first diaphragm  221 . While assembled, the first coil  222  is suspended in the first magnetic gap  214 , and a periphery edge of the first diaphragm  221  is fixed to the upper end  110  of the cover  11 . 
     The second vibrating unit  23  includes a second voice coil  232 , a second diaphragm  231  directly or indirectly coupled to the second voice coil  232 . While assembled, the second voice coil  232  is partially received in the second magnetic gap  215 , and a periphery edge of the second diaphragm  231  is fixed to the frame  12 . 
     Referring to  FIGS. 3-5 , especially to  FIG. 5 , the terminal board  30  includes a first portion  31 , a second portion  32  extending from the first portion  31 , and a third portion  33  extending from the second portion  32 . In the present embodiment, the first portion  31  further includes a first main plate  311 , a first auxiliary plate  312  extending from a middle portion of the first main plate  311 , and a first hole  3111  located in a center portion of the first main plate  311 . The second portion  32  includes a second main plate  321  extending from the first auxiliary plate  312  of the first portion  31 , a pair of second auxiliary plates  322  extending from the second main plate  321 , and two second holes  3221  located in the second auxiliary plates  322 , respectively. The two second auxiliary plates  322  are separately positioned at both sides of the second main plate  321 , respectively. The third portion  33  includes a third main plate  332 , a third auxiliary plate  331  extending from a middle portion of the third main plate  332  to the second main plate  321 , and two third holes  3321  located in two ends of the third main plate  311 , respectively. 
     The first portion  31  of the terminal board  30  is mounted on the upper end  110  of the cover  11  to electrically connect with the first voice coil  222 . The second portion  32  of the terminal board  30  is mounted on the frame  12  to electrically connect with the second voice coil  232 . The third portion  33  of the terminal board  30  is mounted on the lid  132  to electrically connect with an external circuit. 
     The terminal board  30  provides acoustic frequency signals to the first voice coil  222  and the second voice coil  232 . Conventionally, acoustic frequency signals involve high frequency signals and low frequency signals. The high frequency signals and low frequency signals can be synchronously provided to the first voice coil  222  and the second voice coil  232 , respectively. Therefore, the acoustic frequency of the low frequency signals and the high frequency signals can be both output synchronously, which effectively solves the problem of intermodulation of distortion for the high and low acoustic frequencies, and reduces the size of the speaker to be more compact. 
     The cover  11  further includes a first zone  111  located on the upper end  110 , and a first side wall  1113  extending from an edge of the first zone  111 . The first zone includes a first pit  1111  cooperating with the first main plate  311  and a first oblique portion  1112  cooperating with the first auxiliary plate  312 . At least a first protrusion  112  is provided on the first pit  1111  cooperating with the first hole  3111  for fixing the first portion  31  of the terminal board  30  firmly. The pair of first pads  24  is embedded in the first pit  1111  and electrically connected with the first voice coil  222 . Two ends of the first portion  31  press on the pair of first pads  24  for conducting electrical signals to the first voice coil  222 . Similarly, the frame  12  includes a second zone  125  cooperating with the second main plate  321 , two second protrusions  123  extending from the upper surface  121  cooperating with the second holes  3221  for positioning the second portion  32 . The two second auxiliary plates  322  are respectively separately arranged both sides of the first oblique portion  1112  and mounted on the upper surface  121  for electrical connecting with the second voice coil  232  via the two second pads  25 . The case  13  includes a third zone  130  cooperating with the third portion  33  of the terminal board  30 . The third zone further includes a third oblique portion  1301  cooperating with the third auxiliary plate  331  and a third pit  1302  located on the lid  132  cooperating with the third main plate  332 . Two third protrusions  1323  are located on the third pit  1302  accommodated the third holes  3321  for positioning the third portion  32  firmly. 
     In the exemplary embodiment, the first voice coil  222  and the second voice coil  232  are electrically connected with the external circuit via the first main plate  311  and second auxiliary plates  322  of the terminal board  30 , respectively. A distance between the two vibrating unit and the external circuit is reduced for preventing either of the two voice coils from fracturing during the vibration of the vibrating units. 
     While the present invention has been described with reference to a specific embodiment, the description of the invention is illustrative and is not to be construed as limiting the invention. Various of modifications to the present invention can be made to the exemplary embodiment by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.