Abstract:
There is provided a speaker which has a frame structure divided into a first frame and a second frame, wherein tinsel wires are arranged so as not to overlap, with respect to the plane direction, the second frame to which a magnetic circuit is attached, whereby the second frame can be arranged as forward as possible thus enabling reduction of the thickness of the speaker. Also, the first frame and the second frame are both provided with respective frame connection mechanisms and therefore can be easily positioned and connected to each other thus enhancing the workability. The speaker enables further reduction of the thickness without deteriorating input durability and bass range reproduction capability and can be produced with an excellent assembly workability.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the invention 
         [0002]    The present invention relates to a speaker, particularly a speaker having an elongated shape, and also to a method of assembling such a speaker. 
         [0003]    2. Description of the Related Art 
         [0004]    A speaker is used not only for a home audio equipment or a car audio equipment but also for various kinds of electronic devices, such as a TV (television) set, a PC (personal computer), a mobile phone, and a game machine. While an electronic device is increasingly becoming reduced in size and weight, the speaker also is requested to have a reduced dimension with a lower profile and to show a higher performance as well. 
         [0005]    Since the electronic device has a limited space for accommodating a speaker, the dimension of the speaker is strictly restricted, and it is especially requested that the thickness of the speaker be reduced. 
         [0006]    Conventionally, there is provided a low-profile speaker which is structured such that a suspension member (spider) is connected to the outer circumference of a voice coil bobbin (refer to Japanese Patent Application Laid-Open No. 2006-229288 and Japanese Utility Model Patent Application Laid-Open No. S60-142596). 
         [0007]    In order to reduce the thickness of a speaker, a speaker structure is further proposed in which a spider is omitted. This structure, however, is apt to cause a rolling phenomenon thus limiting the volume of a reproduced sound. Also, generally, if a spider is omitted, the vibration of a diaphragm is suspended only by a surround, which results in deteriorating the stability. Especially in the case of a speaker having an elongated shape, since a portion of a surround located at a long side is longer than a portion of the surround located at a short side, the rolling phenomenon is caused more easily if a spider is omitted. 
         [0008]    Referring to  FIG. 11A , a conventional cone speaker is structured such that a tinsel wire  31  to supply an electric signal to a voice coil  30  is connected to a voice coil bobbin  32 . In the case of a speaker designed to have a reduced profile, however, the distance between a tinsel wire  31  and a diaphragm  33  is narrowed as shown in  FIG. 11B , and therefore the amplitude of the diaphragm  33  is restricted due to the presence of the tinsel wire  31 . 
         [0009]    The problem described above is often solved by such a method that a lead wire extending from a voice coil is guided to a diaphragm, and then a tinsel wire is fixed to an appropriate portion of the diaphragm in such a manner as not to interfere with the vibration of the diaphragm. 
         [0010]    In the case of the aforementioned speaker with a reduced profile shown in  FIG. 11B , since the diaphragm  33  is not inclined, there is not a sufficient space behind the diaphragm  33  as well as around a magnetic circuit  34  and a terminal  35 , and therefore it has not been easy to secure a work space for guiding a lead wire and also for fixedly attaching a tinsel wire. 
         [0011]    Also, in the case of the low-profile flat speaker described in Japanese Patent Application Laid-Open No. 2006-229288 or Japanese Utility Model Patent Application Laid-Open No. S60-142596,as shown in  FIG. 11B , the tinsel wire  31  must be arranged in consideration of the location of a spider  36  thus lowering the workability. 
         [0012]    Further, in a conventional low-profile flat speaker, the assembling work, such as forming of a lead wire extending from a voice coil, soldering of a tinsel wire to the lead wire for electrical connection therebetween, and fixing of the tinsel wire, must be conducted behind a diaphragm, wherein the work space is limited and therefore the workability has been forced to be very poor. Under the circumstances, if the work space is increased, then the reduction of the must be abandoned. 
       SUMMARY OF THE INVENTION 
       [0013]    The present invention has been made in order to solve the problems described above, and it is an object of the present invention to provide a speaker which can be produced with an excellent assembly workability and at the same time which enables further reduction of the thickness without deteriorating input durability and bass range reproduction capability. 
         [0014]    In order to achieve the object described above, according to an aspect of the present invention, there is provided a speaker which includes: a diaphragm having an elongated plate-like shape; a first frame disposed rearward of the diaphragm; a surround, the inner circumference of which is connected to the diaphragm and the outer circumference of which is connected to the front face of the first frame; a pair of spider units disposed between the diaphragm and the first frame, separated from each other in the direction of the major axis of the first frame, and connected to the diaphragm and the first frame; a voice coil bobbin attached at the center of the diaphragm; a second frame disposed so as to surround the outer circumference of the voice coil bobbin and connected to the first frame; a magnetic circuit attached to the center of the second frame; a voice coil wound around the voice coil bobbin and suspended in a magnetic gap of the magnetic circuit; tinsel wires connected to lead wires extending from the respective ends of the voice coil; and terminals attached to the first frame and connected to the respective ends of the tinsel wires, 
         [0015]    In the speaker described above, the second frame includes: a circular cylinder portion which has a hollow and within which the magnetic circuit is attached; and a frame connection mechanism disposed at the outer circumference of the circular cylinder portion and connected to the first frame. 
         [0016]    Also, in the speaker, the tinsel wires are arranged at an area that is located radially outward of the outer circumference of the circular cylinder portion of the second frame and that extends along the direction of the major axis of the first frame. 
         [0017]    According to the present invention, a speaker is provided which can be produced with an excellent assembly workability and which enables further reduction of the thickness without deteriorating input durability and bass range reproduction capability. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is an exploded perspective view of a speaker according to an embodiment of the present invention; 
           [0019]      FIG. 2  is a schematic process block diagram for assembling the speaker of  FIG. 1 ; 
           [0020]      FIG. 3  is a schematic process picture corresponding to the process block diagram of  FIG. 2 ; 
           [0021]      FIG. 4A  is a perspective view of a structure in which a diaphragm and a spider assembly are attached to each other; 
           [0022]      FIG. 4B  is a perspective view of a process in which third connecting members are removed from the structure of  FIG. 4A ; 
           [0023]      FIG. 5  is a perspective view of a structure in which a lead wire and a tinsel wire are guided and fixed, seen from a rear side of a first frame; 
           [0024]      FIG. 6  is an enlarged perspective view of a relevant portion of  FIG. 5 ; 
           [0025]      FIG. 7A  is a plan view of the structure shown in  FIG. 5A ; 
           [0026]      FIG. 7B  is a cross sectional view of  FIG. 7A , taken along a line C-C indicated in  FIG. 7A ; 
           [0027]      FIG. 8A  is a plan view of a second frame, seen from a rear side thereof; 
           [0028]      FIG. 8B  is a cross sectional view of  FIG. 8A , taken along a line C-C indicated in  FIG. 8A ; 
           [0029]      FIG. 9A  is a plan view of the speaker (completed) of  FIG. 1 , seen from a rear side thereof; 
           [0030]      FIG. 9B  is a cross sectional view of  FIG. 9A , taken along a line C-C indicated in  FIG. 9A  ; 
           [0031]      FIG. 10A  is an enlarged plan view of a relevant portion of  FIG. 9A ; 
           [0032]      FIG. 10B  is a cross sectional view of  FIG. 10A , taken along a line C-C indicated in  FIG. 10A ; 
           [0033]      FIG. 11A  is a partial cross sectional view of a conventional cone speaker; and 
           [0034]      FIG. 11B  is a partial cross sectional view of a conventional low-profile speaker. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    An exemplary embodiment of the present invention will hereinafter be described with reference to the accompanying drawings. 
         [0036]    A speaker  1  according to an embodiment of the present invention is shown in  FIG. 1  in an exploded perspective manner. 
         [0037]    Referring to  FIG. 1 , the speaker  1  includes: a diaphragm  2  having an elongated plate-like shape; a first frame  3  disposed behind the diaphragm  2 ; a surround  4  attached at the rim of the diaphragm  2 ; a pair of spider units  5  attached to the first frame  3  and the diaphragm  2 ; a voice coil bobbin  6  attached at the center of the diaphragm  2 ; a second frame  7  connected to the first frame  3 ; a magnetic circuit  8  attached at the center of the second frame  7 ; a voice coil  9  wound around the voice coil bobbin  6  and suspended in a magnetic gap of the magnetic circuit  8 ; two lead wires  10  extending from the voice coil  9 ; two tinsel wires  11  connected respectively to the lead wires  10 ; and two terminals  13  attached to the first frame  3  and connected respectively to the ends of the tinsel wires  11 . 
         [0038]    The first frame  3  is shaped so as to define the outline of the speaker  1 . The first frame  3  is provided with a frame connection mechanism which is composed of a pair of first fixing recesses  3   a  and a pair of second fixing recesses  3   b  (refer to  FIG. 7A ). Most of the component members other than the first frame  3  are housed within the first frame  3 , whereby the thickness dimension of the speaker  1  can be successfully reduced. 
         [0039]    The voice coil bobbin  6 , which is attached to the diaphragm  2 , is located substantially at the center of the first frame  3 . The tinsel wire  11  is connected by soldering to the end of the lead wire  10  which extends from the voice coil  9  wound around the voice coil bobbin  6 . As will be described herein later, the lead wire  10  and tinsel wire  11  are fixed at a plurality of places of the first frame  3  and a first connecting member  5   b  of the spider unit  5 . 
         [0040]    The second frame  7  includes: a circular cylinder portion  7   a  which has a hollow and within which the magnetic circuit  8  is attached; and a frame connection mechanism which is formed at the outer circumference of the circular cylinder portion  7   a  and which includes a pair of first fixing blocks  7   b  protruding radially outwardly from the outer circumference of the circular cylinder portion  7   a  in the respective opposite directions along the minor axis of the elongated shape of the first frame  3 , and a pair of second fixing blocks  7   c  protruding radially outwardly from the outer circumference of the circular cylinder portion  7   a  in the respective opposite directions along the major axis of the elongated shape of the first frame  3 . 
         [0041]    The second frame  7  is connected to the rear face of the first frame  3  by mans of the first and second fixing blocks  7   b  and  7   c  and the aforementioned first and second fixing recesses  3   a  and  3   b  of the first frame  3 , as will be described later. 
         [0042]    The magnetic circuit  8  is set inside the circular cylinder portion  7   a.  The magnetic circuit  8  includes a pole piece  8   a,  a magnet  8   b  disposed behind the pole piece  8   a,  and a pot yoke  8   c  disposed behind the magnet  8   b  so as to surround the pole piece  8   a  and the magnet  8   b.  The outer circumference of the pot yoke  8   c  is connected to the inner circumference of the circular cylinder portion  7   a  of the second frame  7 . 
         [0043]    Each of the pair of spider units  5  includes: two spider elements  5   a  arrayed along the direction of the minor axis of the first frame  3 ; the earlier mentioned first connecting member  5   b  which connects between respective one ends of the two spider elements  5   a  and which is fixedly attached to the rear face of the diaphragm  2 ; and a second connecting member  5   c  which connects between respective other ends of the two spider elements  5   a  and which is fixedly attached to the first frame  3 . 
         [0044]    As will be described herein later, when the speaker  1  is assembled, a spider assembly  12  which is composed such that the pair of spider units  5  are connected via two third connecting members  12   a  as shown in  FIG. 1  is attached to the diaphragm  2 . After the spider assembly  12  described above is fixedly attached to the diaphragm  2 , the third connecting members  12   a  are taken away therefrom, which results in that only the pair of spider units  5  of the spider assembly  12  remain attached to the diaphragm  2 . 
         [0045]      FIG. 2  schematically shows an example process flow of assembling the speaker  1  of  FIG. 1 , and  FIG. 3  shows a picture corresponding to the process flow of  FIG. 2 . 
         [0046]    An example method of assembling the speaker  1  will be described with reference to  FIGS. 2 ,  3  and other relevant drawings. 
         [0047]    First, the second connecting members  5   c  of the spider assembly  12  is attached to the first frame  3  as shown in  FIGS. 2 and 3 , thus building a structure S 1  (Step  1 ). 
         [0048]    Then, as shown in  FIG. 4A , the rear face of the diaphragm  2  to which the surround  4  is attached is connected to the structure S 1 , specifically to the first connecting members  5   b  of the spider assembly  12 , whereby a structure S 2  is built (Step  2 ). In this connection, the first frame  3  is omitted in  FIG. 4A  for simplification purpose. 
         [0049]    Subsequently, the third connecting members  12   a  of the spider assembly  12  are removed from the structure S 2  as shown in  FIG. 4B . Also in  FIG. 4B , the first frame  3  is omitted. Here, the third connecting members  12   a  are removed in order to allow the voice coil bobbin  6  to have the largest diameter possible. That is to say, if the third connecting members  12   a  remain attached to the structure S 2 , then the voice coil bobbin  6  to be attached to the diaphragm  2  is forced to have a diameter at most equal to, or smaller than, the distance defined between the two third connecting members  12   a.    
         [0050]    On the other hand, when the third connecting members  12   a  are removed as described above, the voice coil bobbin  6  to be attached is allowed to have a diameter equal up to the dimension of the minor axis of the diaphragm  2 . Also, when the third connecting members  12   a  are removed, the weight of the speaker  1  can be reduced. 
         [0051]    In this connection, it is also possible that the pair of spider units  5  without the third connecting members  12   a  are separately attached to the diaphragm  2 , in which case, however, it is difficult to position the spider units  5  with respect to the diaphragm  2 , and also the pair of spider units  5  must be attached individually, and so the workability is deteriorated. 
         [0052]    Then, the voice coil bobbin  6  is attached to the diaphragm  2  from the rear side of the first frame  3 , whereby a structure S 3  is built (Step  3 ). In this process, the voice coil  9  is beforehand wound around the voice coil bobbin  6 , and the lead wires  10  extending from the respective ends of the voice coil  9  are connected respectively to the tinsel wires  11 . 
         [0053]    After the voice coil  6  is attached to the diaphragm  2  as described above, the lead wires  10  and the tinsel wires  11  are guided and fixed within the first frame  3  to which the diaphragm  2  and the spider units  5  are fixedly attached, and the ends of the tinsel wires  11  are connected to the terminals  13  (not shown in the relevant figures) thereby building a structure S 4  (Step  4 ). 
         [0054]      FIG. 5  perspectively shows a structure, seen from the rear side of the first frame  3 , in which the lead wires  10  and the tinsel wires  11  are guided and fixed as described above, and  FIG. 6  shows a relevant portion of  FIG. 5  in an enlarged manner. 
         [0055]    As seen from  FIGS. 5 and 6 , each of the lead wires  10  is pulled out from the voice coil bobbin  6 , guided to pass by the one end of the spider element  5   a  and along the first connecting member  5   b  and then is connected to the tinsel wire  11  at a point short of a groove  5   d  which is formed at an off-center portion of the first connecting member  5   b.  The lead wire  10  is fixed at a portion shown by a broken line  5   e  indicated in  FIG. 5 . 
         [0056]    Tinsel wire  11  is put through the groove  5   d,  guided outwardly in the direction along the major axis of the speaker  1 , fixedly attached at a positioning and fixing guide  5   g,  then turned around by 90 degrees to be further guided, and is soldered to the terminal  13  (not shown in  FIGS. 5 and 6 ). In  FIG. 6 , a portion  5   h  to which the tinsel wire  11  is adhered and a portion  5   f  to which the tinsel wire  11  is soldered are shown by respective broken lines. 
         [0057]      FIG. 7A  shows a plan view of a structure, seen from the rear side of the first frame  3 , in which the lead wires  10  and the tinsel wires  11  are guided and fixed (refer to  FIG. 5 ), and  FIG. 7B  shows a cross section of  FIG. 7A , taken along a line C-C indicated in  FIG. 7A . Referring to  FIG. 7B , the lead wire  11  is located in front of the spider element  5   a.  The distance between the tinsel wire  11  and the diaphragm  2  is small, but the tinsel wire  11  is fixedly attached at the two portions as shown in  FIG. 6  and therefore is prevented from making contact with the diaphragm  2 . 
         [0058]    As shown in  FIG. 7B , all the component members including the voice coil bobbin  6  are fitted within the thickness of the first frame  3 . Thus, the thickness of the speaker  1  can be reduced. 
         [0059]    After the lead wires  10  and the tinsel wires  11  are guided and fixedly attached as shown in  FIG. 7A , the second frame  7  is attached to the first frame  3  from the rear side of the first frame  3 , whereby a structure S 5  is built (Step  5 ). The second frame  7  is fixedly attached to the first frame  3  such that the first fixing blocks  7   b  of the second frame  7  are fitted in the first fixing recesses  3   a  of the first frame  3 , and the second fixing blocks  7   c  of the second frame  7  are fitted in the second fixing recesses  3   b  of the first frame  3 . 
         [0060]    While the Steps  1  to  5  described above are conducted, the magnet  8   b  is fixedly attached to the pole piece  8   a,  whereby a structure A 1  is built (Step  6 ). Then, the structure A 1  is positioned inside the pot yoke  8   c  by means of a jig (not shown) and fixed therein, whereby a structure A 2  is built (Step  7 ). In this way, the magnetic circuit  8  is completed. And, the magnetic circuit  8  is magnetized, whereby a structure A 3  is built (Step  8 ). 
         [0061]    After the Steps  5  as well as the  8  described above are finished, the outer circumference of the pot yoke  8   c  of the magnetic circuit  8  is connected to the inner circumference of the circular cylinder portion  7   a  of the second frame  7  (Step  9 ). 
         [0062]      FIG. 8A  shows a plan view of an assembly in which the magnetic circuit  8  is attached to the second frame  7 , seen from the rear side of the assembly, and  FIG. 8B  shows a cross section of the assembly of  FIG. 8A , taken along a line C-C indicated in  FIG. 8A . As seen from  FIG. 8B , the magnetic circuit  8  can be attached so as to be fitted almost within the thickness of the second frame  7 . 
         [0063]    As described above, the magnetic circuit  8  is attached to the second frame  7  connected to the first frame  3 . Thus, the speaker  1  shown in  FIG. 1  is completed. 
         [0064]      FIG. 9A  shows a plan view of the speaker  1  completed as described above, seen from the rear side, and  FIG. 9B  shows a cross section of  FIG. 9A , taken along a line C-C indicated in  FIG. 9A .  FIG. 10  shows an enlarged plan view of a relevant portion of  FIG. 9A , and  FIG. 10B  shows a cross section of  FIG. 10A , taken along a line C-C indicated in  FIG. 10A . 
         [0065]    Referring to  FIG. 9B , it is noted that most of all the component members are housed within the thickness of the first frame  3  though the second frame  7  and the pot yoke  8   c  of the magnetic circuit  8  protrude slightly rearwardly from the rear face of the frame  3 . 
         [0066]    Also, as shown in  FIG. 10A , the tinsel wire  11  is not located at a place where the circular cylinder portion  7   a  of the second frame  7  is arranged, and more specifically the tinsel wire  11  is located radially outward of the outer circumference of the circular cylinder portion  7   a.    
         [0067]    The second fixing block  7   c  of the second frame  7  is arranged rearward of the tinsel wire  11 , but since the second fixing block  7   c  is arranged rearward of the front end of the circular cylinder portion  7   a  by a dimension D indicated in  FIG. 10B , and also since the tinsel wire  11  and the second fixing block  7   c  are arranged to be located off each other with respect to the plane direction as shown in  FIG. 10A , the tinsel wire  11  and the second fixing block  7   c  are surely prevented from interfering with each other. 
         [0068]    The tinsel wire  11 , the circular cylinder portion  7   a  and the second fixing block  7   c  are arranged not to overlap one another with respect to the anterior-posterior direction as well as the plane direction in order that the tinsel wire  11 , which has a far larger diameter than the lead wire  10 , is prevented from making contact with the circular cylinder portion  7   a  and the second fixing block  7   c  when the diaphragm  2  vibrates, whereby the second frame  7  is allowed to be entirely positioned as forward as possible, thus contributing to the reduction of the thickness of the speaker  1 . 
         [0069]    Referring to  FIG. 10A , it is noted that a connection point  5   i  between the lead wire  10  and the tinsel wire  11  is arranged not to overlap the second fixing block  7   c  with respect to the plane direction. In this connection, however, since the second fixing block  7   c  is located rearward of the front end of the circular cylinder portion  7   a  by the dimension D (refer to  FIG. 10B ), even in the case if the connection point  5   i  is to be located to overlap the second fixing block  7   c  with respect to the plane direction, it does not happen that the tinsel wire  11  makes contact with the second fixing block  7   c,  and therefore the reduction of the thickness of the speaker  1  is not hampered. 
         [0070]    Thus, since the speaker  1  according to the present embodiment has a frame structure divided into the first frame  3  and the second frame  7 , and since the tinsel wire  11  is arranged so that the tinsel wire  11  and the second frame  7  to which the magnetic circuit  8  is attached do not to interfere with each other with respect to the plane direction, the second frame  7  is allowed to be entirely positioned as forward as possible. Accordingly, the thickness of the speaker can be successfully reduced. 
         [0071]    Also, the first frame  3  and the second frame  7  are both provided with the respective frame connection mechanisms, specifically the first frame  3  is provided with the first fixing recesses  3   a  and the second fixing recesses  3   b,  and the second frame  7  is provided with the first fixing blocks  7   b  and the second fixing blocks  7   c,  whereby the first frame  3  and the second frame  7  can be easily positioned and connected to each other, thus enhancing the workability. 
         [0072]    Further, since the spider assembly  12 , which is formed such that the pair of spider units  5  are connected to each other via the third connecting members  12   a,  is first attached to the diaphragm  2  and then the third connecting members  12   a  is removed, the spider units  5  can be easily attached to the diaphragm, thus enhancing the workability. 
         [0073]    In the embodiment described above, each of the pair of spider units  5  is composed of two of the spider elements  5   a  arrayed along the minor axis direction of the diaphragm  2 , but the present invention is not limited in terms of the number of spider elements and each of the spider units  5  may include three or more of the spider elements  5   a.    
         [0074]    Also, in the embodiment described above, the diaphragm  2  has an elongated shape, but the shape of the diaphragm  2  may be arbitrarily changed. 
         [0075]    The present invention has been described with respect to the specific embodiment described above but is not limited thereto and includes various modifications which may occur to a person skilled in the art, wherein the effects and advantages of the present invention also are not limited to what is described above. That is to say, the present invention can be practiced with various additions and alterations and partial omissions without departing from the spirit and scope of the present invention, which can be derived from what are disclosed in the appended claims as well as from its equivalents