Abstract:
A support structure for supporting and protecting the diaphragm of loudspeaker includes a first elastomer which has a first interface with a camber shape, a second elastomer which has a second interface with a complemental shape of the first interface, the first elastomer and the second elastomer combine together from both sides of the support part of the loudspeaker diaphragm. The separate support structure in the present invention is fit for many kinds of loudspeakers and propitious to increase the technical characteristics of loudspeakers.

Description:
TECHNICAL FIELD 
     The invention relates to the field of electroacoustical technology, more specially to a support structure for positioning of a diaphragm in a loudspeaker and keeping vibration of the diaphragm. In particular, the present invention relates to a separate kind of support structure for the diaphragm. 
     BACKGROUND OF THE INVENTION 
     Diaphragms used in most of the cone and dome loudspeaker in the present market are supported by means of a fold-ring (some including a centering tab), the fold-ring supports the diaphragm so that the diaphragm vibrates under the action of a electroacoustical driving force to output the sound, and the fold-ring and the diaphragm form an integral structure. Some fold-rings and diaphragms are made of same material, both being an integral structure; some fold-rings and diaphragms are made of different materials, both also being an integral structure by bonder means. 
     A lot of efforts are made on the diaphragm, fold-ring and material, as well as technologies in the art in order to obtain the better performance for the loudspeaker. However, the maturated product which is characteristic of the integral support structure is difficult to make a great breakthrough in the technical performance with the state of the art, in particular in the high-pitch and super-high-pitch field. 
     In the conventional ribbon loudspeaker, an aluminum ribbon diaphragm with thickness in the range of about 0.006-0.02 mm is generally used, which is constructed as corrugation to support and keep the vibration of the diaphragm. Although this loudspeaker is an excellent high-pitch unit, the corrugated aluminum ribbon diaphragm is susceptible to slack when it is operated by an electromagnetic force in long term and other strong external force. The diaphragm may become elongated and offset the center area of the magnetic clearance so as to generate distortion at work, the problem concerning the reliability and service life is hard to be resolved over a long time of period. 
     Recently a compound diaphragm of polyimide and aluminum foil has been used in the ribbon loudspeaker, and in a head of the ribbon diaphragm a metal spring in a waveform as a transition section of the support-structural member serves as the integral support structure, which improves the reliability and service life of the ribbon diaphragm in a certain extent, however the problem of stress concentration at a interface between the strip compound diaphragm and the waveform supporting-structural member is still difficult to be resolved since it is not perfect technically. 
     In the planar-film loudspeaker, the diaphragm is a compound plastic-aluminium-foil diaphragm, which is made of the film such as polyester and polyimide as the basic material by means of flexible circuit board technology. The planar-film diaphragm vibrates with the help of the elasticity generated by the plastic film between the retain ring around the planar-film diaphragm and the flexible circuit board. In order to ensure that the diaphragm vibrates with sufficient elasticity, the elastic retain ring of the planar-film diaphragm must have a predetermined width, which results in increasing the total area of the diaphragm of the planar-film loudspeaker. Recently, some of the planar-film loudspeakers available in the market are formed by polyimide as the basic material. This type product is tested after signal input, as a result, it is found that partial or entire diaphragm has permanent deformation. This means that the elasticity of the supporting ring of the diaphragm cannot sufficiently satisfy the requirement of the diaphragm vibration. As a result of the permanent deformation the diaphragm offsets the normal work area and produces distortion. 
     The above mentioned support structure of the three diaphragm has a common character that the support structure and the diaphragm are formed as an integral piece. This kind structure has a certain limitation in technology. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to overcome the drawbacks above mentioned in the prior art, and to improve the performance of loudspeaker. 
     To this end, the loudspeaker diaphragm according to the invention is a separate kind of support structure, this support structure is used for positioning the loudspeaker diaphragm and keeping the vibration of diaphragm, wherein the support structure comprises: a first elastic body which has a first engaged face having a curved-surface shape; and a second elastic body which has a second engaged face, a curved-surface shape of the second engaged face complementarily matches the curved-surface shape of the first engaged face; the first engaged face of the first elastic body and the second engaged face of the second elastic body engage each other to clamp a supported portion of the loudspeaker diaphragm in opposite relation from two sides of the supported portion. 
     According to diaphragm support structure of the invention, the elastic bodies clamp the supported portion of the diaphragm by means of the engaged faces to keep supporting, there is no other connecting means such as an adhesive or the like between the elastic body and the diaphragm, hence a separate support structure is formed between the supported portion of the diaphragm and the curved-surface elastic body. In that manner, the curved-surface elastic bodies support and locate the diaphragm in a center work area for diaphragm with the supported portion, in work state the diaphragm keeps vibrating at the corresponding amplitude with the audio signal. 
     In the separate kind of support structure according to the invention, the loudspeaker diaphragm may be flexible or rigid. 
     In addition, compared with the integral support structure, for the cone and dome loudspeaker the separate support structure according to the invention eliminates the fold-ring to reduce the vibrating mass, which is particularly important for playing high frequency signal. Furthermore when the support structure of the present invention is applied to the ribbon loudspeaker and the planar-film loudspeaker, it may overcome the deficiency of the insufficient elastic deformation of the diaphragm material itself. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is an exploded perspective view of the support structure of the loudspeaker diaphragm according to a first embodiment of the invention. 
         FIG. 2  is a sectional view of the support structure according to the loudspeaker diaphragm of the invention. 
         FIG. 3  is a sectional view of the support structure of the loudspeaker diaphragm according to a second embodiment of the invention. 
         FIG. 4  is a sectional view of the support structure of the loudspeaker diaphragm according to a third embodiment of the invention. 
         FIG. 5  shows an overall configuration of various support structures. 
         FIG. 6  is a representative view of the cone loudspeaker used with the separate support structure. 
         FIG. 7  is a representative view of the dome high-pitch loudspeaker used with the separate support structure. 
         FIG. 8  is a representative view of the extra-long ribbon loudspeaker (a portion with the diaphragm) used with the separate support structure. 
         FIG. 9  is the exemplar diagram of the planar-film loudspeaker (a portion with the diaphragm) used with the separate support structure. 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS 
       1  first curved-surface elastic body 
       2  second curved-surface elastic body 
       3 - 1  flexible supported portion 
       3 - 2  rigid supported portion 
       4  first fixation member of the curved-surface elastic body 
       5  second fixation member of the curved-surface elastic body 
       6  adhesive layer 
       7  flexible diaphragm 
       8  rigid diaphragm 
       9  first macromolecular curved-surface elastic body of hollow structure 
       10  second macromolecular curved-surface elastic body of hollow structure 
       11  fixed section of flexible diaphragm 
       12  engaged face of first curved-surface elastic body 
       13  engaged face of second curved-surface elastic body 
       14  fixed section of first metallic curved-surface elastic body 
       15  fixed section of second metallic curved-surface elastic body 
       16  first metallic curved-surface elastic body 
       17  second metallic curved-surface elastic body 
       18  first curved-surface elastic body in bar shape 
       19  second curved-surface elastic body in bar shape 
       20  second curved-surface elastic body in circular shape 
       21  second curved-surface elastic body in square shape (with rounded corner) 
       22  second curved-surface elastic body in U-shape 
       23  cone diaphragm 
       24  voice coil (winding) 
       25  dome diaphragm 
       26  electrical terminal of diaphragm conducting circuit for a planar-film loudspeaker 
       27  diaphragm conducting circuit for a planar-film loudspeaker 
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, embodiments of the invention will be described in further detail with reference to the drawings. 
     In  FIG. 1 , there is shown a separate support structure for the loudspeaker diaphragm according to the first embodiment of the invention, and this kind of support structure is used for retaining the positioning of the diaphragm and keeping the vibration of the loudspeaker diaphragm. The support structure includes a first curved-surface elastic body  1 , a second curved-surface elastic body  2  and a supported portion  3 - 1  of the loudspeaker diaphragm. In this embodiment, the first curved-surface elastic body  1  has a first engaged face  12  with a convex curved-surface shape, and the second curved-surface elastic body  2  has a second engaged face  13  with a concave curved-surface shape which is complementary to the curved-surface shape of the first curved-surface elastic body. The first engaged face  12  of the first curved-surface elastic body and the second engaged face  13  of the second curved-surface elastic body engage oppositely from both sides of the supported portion  3 - 1  of the loudspeaker diaphragm  7  and clamp the supported portion  3 - 1 . It should be noted that there is no any connection means, such as an adhesive, between the first engaged face and the second engaged face, which is particularly benefit to the loudspeaker performance. 
     As shown in  FIG. 2 , in the first embodiment of the invention the diaphragm for the loudspeaker is a flexible diaphragm  7 . The supported portion  3 - 1  of the diaphragm is sandwiched between both engaged faces of the two curved-surface elastic bodies  1  and  2 , for example, the flexible diaphragm  7  may be a ribbon diaphragm for the ribbon loudspeaker or a planar-film diaphragm for the planar-film loudspeaker. A first fixation member for connecting to the curved-surface elastic body is denoted by reference numeral  4  in  FIG. 2 , the first curved elastic body  1  is fixed in the first fixation member  4  by means of insertion. A second fixation member for connecting to the curved-surface elastic body is denoted by the reference numeral  5 , as shown in the figure, the second curved-surface elastic body  2  is fixed in the second fixation member  5  by means of an adhesive layer  6 . It should be noted that the connection means between the fixation members and the elastic bodies is not limited, and the connection means may be selected according to the operation environment and manufacture technology. 
     The first and second curved-surface elastic bodies  1 ,  2  may be made of macromolecular resilient material, such as rubber, polyamino-rubber etc. In the ribbon loudspeaker and the planar-film loudspeaker, for example, the elastic bodies may preferably be made from thermal-resistant resilient material of macromolecule, such as fluo-rubber, silicon rubber etc, since the current flows through the conductive circuit in the diaphragm and the temperature may arise up to 100° C. or above under a maximum power. 
     Also, the support structure shown in  FIG. 2  is the combination of the curved-surface elastic body and the supported portion in the ribbon loudspeaker and the planar-film loudspeaker which comprise the flexible diaphragm. Normally, the flexible diaphragm has a fixed section or a fixed area where the diaphragm is fixedly connected to a loudspeaker body so as to fix the diaphragm; the separate support structure formed by the curved-surface elastic bodies serves to support and tension the flexible diaphragm so that the diaphragm is positioned at a center working region. When the supported portion of the diaphragm is under the action of the drive forcing from an audio signal, both the engaged faces of the two curved-surface elastic bodies open or close so that the diaphragm can stretch or withdraw; the separate support structure supports and keeps the diaphragm vibrating within a predetermined amplitude, while ensures that the vibration of the diaphragm does not exceed an elasticity limit. In the ribbon loudspeaker, the position of the curved-surface elastic bodies  1 ,  2  is generally provided in the inside of the fixed section of ribbon diaphragm, and the elastic body may be provided on either end or both ends of the ribbon diaphragm. In addition, in the extra-long ribbon loudspeaker diaphragm and the support structure of the curved-surface elastic body shown in  FIG. 8 , if the length of the ribbon diaphragm is longer than 300 mm in the extra-long ribbon loudspeaker as shown in the figure, one pair or more pairs of curved-surface elastic bodies may be arranged at the middle of the diaphragm in order to further support and stabilize the flexible diaphragm. As shown in  FIG. 9 , in the planar-film loudspeaker, the position of the separate support structure including curved-surface elastic bodies  1  and  2  is generally between a flexible conductive circuit  27  and a retaining ring of the diaphragm. 
     Furthermore, in the case that the loudspeaker diaphragm is flexible one, the minimum curvature radius of the first curved-surface elastic body  1  and the second curved-surface elastic body  2  is larger than or equal to the minimum allowable flex radius of the flexible diaphragm  7 . Meanwhile, the difference between a length of a curved-surface line of a section plane of the first and second elastic bodies and a length of a straight line of the section plane of the first and second elastic bodies is larger than or equal to the difference between a line length of the diaphragm at its maximum amplitude and a line length of the diaphragm at minimum amplitude. 
       FIG. 3  shows the support structure of the loudspeaker diaphragm according to the second embodiment of the present invention. Similarly, the structure shown in  FIG. 3  is also a separate support structure for the loudspeaker diaphragm. In comparison with the structure shown in  FIG. 2 , the loudspeaker diaphragm in  FIG. 3  is a rigid diaphragm  8 , which has a rigid supported portion  3 - 2 . The first curved-surface elastic body  9  and the second curved-surface elastic body  10  are both hollow elastic pieces, which are made of resilient material of macromolecule. Similarly, the supported portion  3 - 2  of the rigid diaphragm  8  is sandwiched between the first engaged face of the first curved-surface elastic body  9  and the second engaged face of the second curved-surface elastic body  10  so that it is able to support and retain the loudspeaker diaphragm. As shown in the figure, the first hollow curved-surface elastic body  9  has a convex curved-surface shape and the second hollow curved-surface elastic body  10  has a concave curved-surface shape, the both curved-surface faces of the elastic bodies  9  and  10  engage and match each other, the supported portion  3 - 2  of the rigid diaphragm is sandwiched between the two complementary curved surfaces, and the supported portion  3 - 2  of the rigid diaphragm has a suitable shape that matches with the curved surfaces of the curved-surface elastic bodies  9 ,  10 . Meanwhile, in order to maintain the stability in a radial direction during the compression of hollow curved-surface elastic bodies, the hollow curved-surface elastic bodies may be configured in a drum structure. Similarly, the supported portion  3 - 2  of the rigid diaphragm and the first and second elastic bodies  9 ,  10  form as a separate structure, that is, there is no any connection means, such as an adhesive, between them. 
     The first curved-surface elastic body  9  is fixed in the first fixation member  4  by means of insertion, while the second elastic body  10  is fixed in the second fixation member  5  by means of an adhesive. The connection means between the fixation member and the elastic bodies is not limited, and the connection means may be selected according to the operation environment and manufacture technology. 
     It is to be again noted that the separate support structure shown in  FIG. 3  is the combination of rigid supported portion  3 - 2  and the curved-surface elastic bodies  9 ,  10 , this kind of support structure can subject to vibration and maintain its curved shape. The support structure of curved-surface elastic body allows the rigid diaphragm to vibrate under a driving force in the direction of the vertical axis (perpendicular to a plane of the diaphragm), and the support structure with the curved-surface elastic bodies can further stabilize the radial position of the rigid diaphragm. 
     When the loudspeaker diaphragm is rigid one, the minimum resilient displacement of the elastic body is larger than or equal to the maximum vibration amplitude of the loudspeaker diaphragm. 
       FIG. 4  shows a support structure of metallic thin plate for a diaphragm according to the third embodiment of the present invention. The support structure includes a first metallic curved-surface elastic body  16  having a first engaged face and a second metallic curved-surface elastic body  17  having a second engaged face, the engaged faces of the two metallic curved-surface elastic bodies  16  and  17  have S-shape curved matching surfaces, a diaphragm is sandwiched between the two engaged faces which are complementarily matched together. It should be noted that the separate support structure is formed of the supported portion and the first and second elastic bodies  16 ,  17 , that is, there is no connection means, such as an adhesive, between them. 
     The first and second metallic curved-surface elastic bodies have fixation sections  14  and  15  for the elastic bodies, respectively, so that they may be connected to the loudspeaker body by means of welding, a fastener, or an insertion slot. In the illustrated embodiment the flexible diaphragm  7  is sandwiched between the metallic curved-surface elastic bodies. In such a manner, the metallic curved-surface elastic bodies can support and maintain the positioning of the rigid diaphragm and keep its vibration as well. The metallic curved-surface elastic body may be made of material such as phosphor bronze and beryllium copper, etc. 
     The curved-surface shape of the elastic body in the support structure may be various, for example in the shapes of waveform, sinusoidal waveform, S-form, V-form, U-form, C-form, M-form, W-form and so on. 
     It can be found from the above mentioned embodiments that the separate support structure according to the invention may be not only used in the loudspeaker having the flexible diaphragm, such as the ribbon loudspeaker, planar-film loudspeaker as well as the dome-section high-pitch loudspeaker; but also may be used in the loudspeaker having the rigid diaphragm, such as the cone loudspeaker as shown in  FIG. 6  and the dome high-pitch loudspeaker as shown in  FIG. 7 . As shown in  FIG. 6 , a cone diaphragm  23  in the cone loudspeaker is sandwiched and fixed between the first curved-surface elastic body  1  and the second curved-surface elastic body  2 ; as shown in  FIG. 7 , a dome diaphragm  25  in the dome high-pitch loudspeaker is sandwiched and fixed between the first curved-surface elastic body  1  and the second curved-surface elastic body  2 . 
     The entire configuration of the elastic body may have many embodiments according to the type of the loudspeaker and the diaphragm structure.  FIG. 5  shows some configurations, wherein reference numerals  18  and  19  show a bar-shaped curved-surface elastic body, reference numeral  20  shows a circular curved-surface elastic body, reference numeral  21  shows a square curved-surface elastic body with rounded corner, and reference numeral  22  shows a U-shaped curved-surface elastic body. Furthermore the elliptical shape may also be adopted as the entire shape. 
     The foregoing description is representative. The skilled in the art may make modifications without departing the main intension and spirit of the invention, for example, the hollow curved-surface elastic body can be used in combination with the flexible diaphragm, or the solid curved-surface elastic body can be used in combination with the rigid diaphragm. The scope for protection of the invention is determined by the attached claims.