Patent Publication Number: US-10779076-B2

Title: Damper and speaker apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a damper and a speaker apparatus including the damper. 
     BACKGROUND ART 
     There has been proposed a speaker apparatus including a frame, a voice coil bobbin, a diaphragm connected to the voice coil bobbin, and a damper for fixing the diaphragm to the frame (see, for example, Patent Literature 1). The conventional speaker apparatus described in Patent Literature 1 includes restrictive protrusions for preventing excessive movement of the voice coil bobbin and prevents contact between the voice coil bobbin and other members. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 11-262088 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     Incidentally, in general, a damper includes a corrugation portion which is concentrically formed to surround an opening and has a convexoconcave arranged in a radial direction in order to stabilize the direction of oscillation of the voice coil bobbin and to abate noise by suppressing unnecessary natural oscillations of oscillatory systems (diaphragm, damper, edge and the like). Regarding such a damper, an attachment portion (circumference of an opening portion) on the inner side of the corrugation portion is connected to the voice coil bobbin, and an attachment portion on the outer side is connected to the frame. With a speaker apparatus including such a damper, there is a possibility that, when an excessive input signal (e.g., signal by noise) is entered, the voice coil bobbin is driven to oscillate accordingly and the amplitude of the oscillatory systems following the voice coil bobbin is increased, resulting in damage. 
     Given the above, one conceivable configuration is that the damper is generally formed of a hard-to-deform material so that the amplitude of the oscillatory system as the voice coil bobbin is driven by an excessive input signal is suppressed. However, with such a damper, the amplitude of the oscillatory system is reduced even without an excessive input signal and the sound pressure of radiation sound with respect to the magnitude of the input signal is reduced, thereby reducing the efficiency of the speaker apparatus. 
     It is one exemplary object of the present invention to provide a damper and a speaker apparatus including the damper, the damper suppressing damage to an oscillatory system due to an excessive input signal and enables an increase in efficiency of the speaker apparatus. 
     Solution to Problem 
     In order to solve the problem and achieve the object, a damper of the present invention according to a first aspect of the present invention is characterized by including: an opening portion having one opening; a corrugation portion formed around the opening portion, the corrugation portion including at least one convexoconcave arranged in a radial direction; a planar portion formed around the corrugation portion, the planar portion having a planar surface; and an attachment portion formed around the planar portion, wherein the planar surface is extended substantially parallel to the attachment portion at a height in a thickness direction different from that of the attachment portion. 
     Meanwhile, the speaker apparatus of the present invention according to an eleventh aspect of the present invention is characterized by including the damper according to the first aspect. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating a damper according to Example 1 of an embodiment of the present invention. 
         FIG. 2  is a plan view illustrating the damper. 
         FIG. 3  is a cross-sectional view cut along line A-A and a cross-sectional view cut along line B-B of  FIG. 2 . 
         FIG. 4  is a cross-sectional view cut along line C-C of  FIG. 2 . 
         FIG. 5  is a cross-sectional view illustrating a state where the damper is deformed. 
         FIG. 6  is a schematic view illustrating a state where an external force is applied to the damper and the diaphragm and the displacement is measured. 
         FIG. 7  is a graph illustrating a relationship between an external force applied to the damper and the displacement. 
         FIG. 8  is a perspective view illustrating the damper according to Example 2. 
         FIG. 9  is a cross-sectional view cut along line D-D of  FIG. 8 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following, an embodiment of the present invention will be described. A damper according to the embodiment of the present invention includes an opening portion having one opening, a corrugation portion formed around the opening portion and including at least one convexoconcave arranged in a radial direction, a planar portion formed around the corrugation portion and having a planar surface, and an attachment portion formed around the planar portion, wherein the planar surface is extended substantially parallel to the attachment portion at a height in the thickness direction different from that of the attachment portion. 
     The planar portion of the damper has a planar surface. When a force in the thickness direction is applied to the damper, the planar portion is less deformable than the corrugation portion. Accordingly, when the voice coil bobbin is driven to oscillate in the thickness direction by an excessive input signal, the presence of the planar portion suppresses undue deformation of the damper as a whole, reducing the amplitude of the oscillatory system, thereby enabling suppression of damage to the oscillatory system. Furthermore, in the absence of an excessive input signal, the planar portion hardly prevents deformation of the corrugation portion in response to an input signal. Therefore, the sound pressure with respect to the magnitude of an input signal can be ensured. 
     Furthermore, the planar surface is extended at a height in the thickness direction different from that of the attachment portion. Thus, a portion extending in the thickness direction (rising portion) is formed between the planar surface and the attachment portion. When the voice coil bobbin is driven to oscillate in the thickness direction by an excessive input signal, the rising portion can be deformed and suppresses a stress from being concentrated on a boundary between the planar surface and the attachment portion to produce rupture of the damper in the vicinity of the boundary. 
     The planar portion preferably has the one planar surface. Thus, as described above, damage to the oscillatory system due to an excessive input signal is suppressed and the sound pressure with respect to the magnitude of an input signal can be ensured with the simple configuration. 
     The planar surface is preferably arranged on one side in the thickness direction beyond the attachment portion. In addition, the one side may be either the sound radiation side or the opposite side of the speaker apparatus. 
     The planar portion preferably has a plurality of the planar surfaces. Thus, the height in the thickness direction of each planar surface with respect to the attachment portion can be set properly, enabling adjustment of ease of deformation of the planar portion. In addition, the plurality of planar surfaces may be either arranged side by side along a radial direction or arranged side by side along a circumferential direction. 
     The plurality of planar surfaces preferably arranged side by side along a circumferential direction. Thus, a force applied to the damper by the voice coil bobbin is homogenized in a radial direction, enabling suppression of undue partial deformation of the damper. 
     The plurality of planar surfaces preferably includes a first planar surface and a second planar surface, which is arranged at a height in the thickness direction different from that of the first planar surface. The first planar surface and the second planar surface both may be arranged either on the sound radiation side or on the opposite side beyond the attachment portion, and one of the first planar surface and the second planar surface may be arranged on the sound radiation side and the other may be arranged on the opposite side. Such a configuration enables an increase in mechanical strength of the damper. 
     It is preferable that the first planar surface and the second planar surface are alternately arranged side by side in the circumferential direction. Thus, as described above, the ease of deformation of the planar portion can be adjusted easily. 
     The opening is formed in a circular shape in plan view. The plurality of planar surfaces preferably has rotational symmetry relative to an axis of symmetry, which is the axis that passes through the center of the opening and is parallel to the thickness direction. Thus, when the voice coil bobbin is oscillated in the thickness direction, the force applied to the damper from the voice coil bobbin is symmetric relative to the axis of symmetry. Thus, undue partial deformation of the damper is suppressed, and the acoustic characteristics of the speaker apparatus can be improved. In addition, it is sufficient that the plurality of planar surfaces have two- or more-fold rotational symmetry. 
     It is preferable to further include a connection for connecting the planar surfaces, which are adjacent to one another in the circumferential direction. Thus, the circumferentially adjacent planar surfaces are positioned and retained by the connection at different heights in the thickness direction. 
     It is preferable that the first planar surface is arranged on one side beyond the attachment portion in the thickness direction and the second planar surface is arranged on the other side beyond the attachment portion in the thickness direction. Thus, the deformability of the damper on the sound radiation side becomes equivalent to the deformability on the opposite side, enabling favorable preservation of the acoustic characteristics, e.g., distortion. 
     EXAMPLES 
     In the following, examples of the present invention will be described in detail. In Example 2, components similar to or having the same functions as components described in Example 1 are designated by the same reference numerals as those of Example 1, and the description is omitted. 
     Example 1 
       FIG. 1  is a schematic view illustrating a damper  1 A according to Example 1 of the present invention.  FIG. 2  is a plan view illustrating the damper  1 A.  FIGS. 3(A), 3(B)  and  4  are cross-sectional views illustrating the damper  1 A.  FIG. 5  is a cross-sectional view illustrating a state where the damper  1 A is deformed. In the present example, the thickness direction, the radial direction, and the circumferential direction are as indicated in  FIGS. 1 to 4 . 
     The damper  1 A is generally formed in a plate shape and is formed of a fabric impregnated, for example, with phenol resin. The damper  1 A includes an opening portion  2  having an opening O, a corrugation portion  3  formed around the opening portion  2 , a planar portion  4 A formed around the corrugation portion  3 , and an attachment portion  5  formed around the planar portion  4 A. The damper  1 A is mounted on a speaker apparatus, which is not illustrated. 
     The opening portion  2  is formed around the opening O having a circular shape in plan view. An inner wall  21  having a cylindrical shape is configured to be attached to a voice coil bobbin of the speaker apparatus, which is not illustrated. 
     As illustrated in cross-section in  FIGS. 3(A) and 3(B) , the corrugation portion  3  is formed of a plurality (three for each in the present example) of corrugated convexoconcaves  31  arranged side by side in the radial direction. The corrugation portion  3  is formed in an annular shape surrounding the opening portion  2 . 
     The planar portion  4 A includes a plurality ( 16  in the present embodiment) of planar surfaces  40 A extending substantially parallel to the attachment portion  5  at a height in the thickness direction different from that of the attachment portion  5 , connections  43  for connecting the planar surfaces  40 A to one another, and rising portions  44  arranged at two points across the planar surface  40 A in the radial direction. 
     The plurality of planar surfaces  40 A include eight first planar surfaces  41  arranged on one side (upper side) in the thickness direction beyond the attachment portion  5 , as illustrated in  FIG. 3(A)  in cross-section, and eight second planar surfaces  42  arranged on the other side (lower side) in the thickness direction beyond the attachment portion  5 , as illustrated in  FIG. 3(B)  in cross-section. The first planar surfaces  41  and the second planar surfaces  42  are alternately arranged side by side in the circumferential direction. Furthermore, the plurality of planar surfaces  40 A have eight-fold rotational symmetry relative to an axis of symmetry, which is the axis that passes through the center of the opening O and is parallel to the thickness direction. Specifically, when the damper  1 A is generally rotated about the axis of symmetry in multiples of 45 degrees, the plurality of planar surfaces  40 A overlaps the pre-rotation shape. 
     The connection  43  is arranged between the first planar surface  41  and the second planar surface  42 , which are adjacent to one another in the circumferential direction. As illustrated in  FIG. 4 , which is a cross-sectional view along the circumferential direction, the connection  43  includes a pair of inclination portions  431 , which are inclined in the circumferential direction and are extended in the thickness direction, and an intermediate portion  432 , which is arranged between the pair of inclination portions  431  and is extended in the circumferential direction. The connection  43  connects the first planar surface  41  and the second planar surface  42 . The intermediate portion  432  is arranged at the substantially same height as the attachment portion  5  in the thickness direction (position indicated by the chain double-dashed line). The connection  43  may be extended in the thickness direction to connect the first planar surface  41  and the second planar surface  42  without circumferential inclination, and the intermediate portion  432  may be omitted. 
     The rising portions  44  are arranged between the planar surface  40 A and the corrugation portion  3  and between the planar surface  40 A and the attachment portion  5 . As illustrated in  FIG. 3(A) , the rising portions  44  lying across the first planar surface  41  in the radial direction are radially inclined and extended upward from the corrugation portion  3  and the attachment portion  5 . As illustrated in  FIG. 3(B) , the rising portions  44  lying across the second planar surface  42  in the radial direction are radially inclined and extended downward from the corrugation portion  3  and the attachment portion  5 . Thus, as the rising portions  44  are arranged, the planar surface  40 A is arranged on a plane at a height in the thickness direction different from that of the attachment portion  5 . The rising portion  44  may have a shape extending along the thickness direction without inclination. 
     The attachment portion  5  is formed planar and is extended along the radial direction and the circumferential direction. A lower side surface as illustrated in  FIG. 1  is attached to the frame of the speaker apparatus as an attachment surface. Specifically, the damper  1 A is arranged on the speaker apparatus with an upper side surface facing the sound radiation side. 
     In the following, a state where the damper  1 A is deformed is described with reference to  FIG. 5 .  FIG. 5  illustrates a part of the damper  1 A illustrated in cross-section in the same position as  FIG. 3(A) . The damper  1 A is similarly deformed in the same position as  FIG. 3(B)  in the manner described below. 
     When the amplitude of the voice coil bobbin is small, as illustrated by the solid line in  FIG. 5 , the corrugation portion  3  of the damper  1 A is stretched such that the height of the corrugated convexoconcave  31  is lowered and distance between the dent and the protrusion constituting the convexoconcave  31  is increased. Furthermore, the planar portion  4 A of the damper  1 A is deformed such that an angle made by the rising portion  44  and the planar surface  40 A varies. The planar surface  40 A is less deformable and deflectable than the corrugation portion  3 . 
     When the amplitude of the voice coil bobbin is large, as the amount of stretch of the corrugation portion  3  is sufficiently large, the corrugation portion  3  hardly further deforms. The planar portion  4 A is deformed such that an angle made by the planar surface  40 A and the attachment portion  5  varies and an angle made by the rising portion  44  and the planar surface  40 A varies. The planar surface  40 A almost retains the original shape. Thus, as the corrugation portion  3  hardly deforms and the planar surface  40 A hardly deforms, even when the voice coil bobbin is oscillated by an excessive input signal, undue general deformation of the damper  1 A is suppressed, enabling a reduction in amplitude of the oscillatory system. 
     Regarding a conventional damper in which a corrugation portion is generally formed between the opening portion and the attachment portion without a planar portion, when a voice coil bobbin is oscillated by an excessive input signal, the damper is generally largely stretched. As a result, the amplitude of an oscillatory system can be excessively large, causing damage to the oscillatory system. 
     Furthermore, regarding such a conventional damper, in cases where the corrugation portion in the vicinity of the attachment portion is omitted and a planar surface extending in the same plane as the attachment portion (at the same height in the thickness direction) is formed in the above portion, when the voice coil bobbin is oscillated by an excessive input signal, undue deformation of the damper can be suppressed as with the damper  1 A of Example 1. However, there is a possibility that a force is concentrated on a boundary between the planar surface and the attachment portion, resulting in rupture of the damper in the vicinity of the boundary. 
     With the aforementioned configuration, as the damper  1 A includes the planar surface  40 A, excessive deformation of the oscillatory system due to an excessive input signal is suppressed, enabling suppression of damage to the oscillatory system. Furthermore, the planar surface  40 A hardly prevent deformation of the corrugation portion  3  due to a normal input signal. Therefore, the sound pressure with respect to the magnitude of an input signal can be ensured, enabling an increase in efficiency of the speaker apparatus. 
     Furthermore, as the planar surface  40 A is extended at a height in the thickness direction different from that of the attachment portion  5 , the rising portions  44  are deformed when the voice coil bobbin is oscillated, and rupture of the damper  1 A in the vicinity of the boundary between the planar surface  40 A and the attachment portion  5  can be suppressed. 
     Furthermore, as the first planar surface  41  is arranged on one side of the attachment portion  5  and the second planar surface  42  is arranged on the other side of the attachment portion  5 , the deformability of the damper  1 A on the sound radiation side becomes equivalent to the deformability on the opposite side, enabling favorable preservation of the acoustic characteristics, e.g., distortion. 
     Furthermore, as the plurality of planar surfaces  40 A have rotational symmetry, when the voice coil bobbin is oscillated in the thickness direction, a force applied to the damper  1 A from the voice coil bobbin becomes symmetric relative to the axis of symmetry, enabling suppression of undue partial deformation of the damper. 
     In the following, displacement with respect to an external force to the damper  1 A of Example 1, a damper  100  of a conventional example, and a damper  200  of a comparative example is described on the basis of experimental results. Here, the damper  100  of the conventional example has an inside diameter (diameter of an opening portion) and an outside diameter, which are equal to those of the damper  1 A of the present example, and includes a corrugation portion generally between the opening portion and an attachment portion. Furthermore, the damper  200  of the comparative example has the substantially same shape as the damper  100  of the conventional example and is formed of a material that is less deformable than that of the damper  100  of the conventional example. 
     Here, the material of the damper  1 A is cotton, blended fabric or the like. The material of the dampers  100 ,  200  is chemical fiber or the like (the damper  200  of the comparative example is formed of chemical fiber the hardness of which is greater than that of the damper  100  of the conventional example). Both dampers  100 ,  200  are generally formed in a circular shape. The dimensions of each part are indicated in Table 1. The thickness indicates the thickness dimension of a damper at a planar part, e.g., the attachment portion. Each of dampers  1 B,  100 ,  200  generally has a substantially uniform thickness. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                   
                   
                 DIMENSION 
                   
               
               
                   
                 OUTSIDE 
                   
                 RADIAL 
                 RADIAL 
                 OF PLANAR 
               
               
                   
                 DIAMETER 
                   
                 DIMENSION OF 
                 DIMENSION 
                 PORTION IN 
               
               
                   
                 OF ENTIRE 
                 DIAMETER 
                 CORRUGATION 
                 OF PLANAR 
                 THICKNESS 
               
               
                   
                 DAMPER 
                 OF OPENING 
                 PORTION 
                 PORTION 
                 DIRECTION 
                 THICKNESS 
               
               
                   
                 (mm) 
                 (mm) 
                 (mm) 
                 (mm) 
                 (mm) 
                 (mm) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 EXAMPLE 1 
                 ϕ 92 
                 ϕ 31 
                 16 
                 8 
                 1 
                 0.3 
               
               
                 CONVENTIONAL 
                 ϕ 92 
                 ϕ 31 
                 24 
                 — 
                 — 
                 0.3 
               
               
                 EXAMPLE 
               
               
                 COMPARATIVE 
                 ϕ 92 
                 ϕ 31 
                 24 
                 — 
                 — 
                 0.3 
               
               
                 EXAMPLE 
               
               
                   
               
            
           
         
       
     
     With regard to each of the dampers  1 A,  100 ,  200 , displacement with respect to an external force was measured with a displacement measurement means  300  as illustrated in  FIG. 6 . Specifically, one end of each of the dampers  1 A,  100 ,  200  was connected to the displacement measurement means  300 , and the other end was fixed. An external force in an upward and downward direction (in thickness direction) was applied to the displacement measurement means  300 , and the magnitude of the displacement of the displacement measurement means  300  was measured. Specifically, the displacement of the displacement measurement means  300  as the displacement measurement means  300  was oscillated as with the voice coil bobbin was measured. The results are indicated in  FIG. 7 . The displacement indicated in  FIG. 7  is an average value of the displacement due to upward application of an external force and the displacement due to downward application of an external force in  FIG. 6 . 
     Regarding the damper  100  of the conventional example and the damper  200  of the comparative example, the displacement is substantially proportional to the external force. The damper  100  of the conventional example has a large gradient so that the displacement can be ensured even when an external force is small. Meanwhile, the displacement becomes excessively large in a region where an external force is large. The damper  200  of the comparative example has a small gradient so that the displacement can be small in a region where an external force is large. Meanwhile, the displacement becomes excessively small in a region where an external force is small. In contrast, regarding the damper  1 A of the present example, which employs a material which is more flexible than that of the conventional example, a curve indicating the damper  1 A has a large gradient in a region where an external force is small, is bent near 15N, and has a small gradient in a region where an external force is greater than the above. The damper  1 A ( 1 B) according to the present example (and Example 2 to be described below) has a small displacement in an upward and downward direction when an external force is large. Therefore, a material which is more flexible than that of the conventional example can be used. 
     The damper  1 A is capable of having a displacement greater than that of the dampers  100 ,  200  of the conventional example and the comparative example when an external force is small and having displacement smaller than that of the damper  100  of the conventional example when an external force is large. Accordingly, a speaker apparatus equipped with the damper  1 A has superior efficiency than a speaker apparatus equipped with the dampers  100 ,  200  of the conventional example and the comparative example. Furthermore, the oscillatory system is less likely to be damaged as compared to that of the speaker apparatus equipped with the damper  100  of the conventional example. 
     Example 1 describes the damper  1 A including the opening portion  2  having one opening, the corrugation portion  3 , which is formed around the opening portion  2  and includes at least one convexoconcave arranged in the radial direction, the planar portion  4 A, which is formed around the corrugation portion  3  and has the planar surface  40 A, and the attachment portion  5 , which is formed around the planar portion  4 A, wherein the planar portion  4 A only includes planar surfaces arranged at two heights: the first planar surface  41 , which is extended substantially parallel to the attachment portion  5  at a height in the thickness direction different from that of the attachment portion  5  and the second planar surface  42 , which is formed parallel to the first planar surface  41  and is arranged at a different height in the thickness direction. However, the planar portion may further include an additional planar surface at a height different from those of the first planar surface  41  and the second planar surface  42 . 
     Example 2 
     As illustrated in  FIG. 8 , the damper  1 B according to Example 2 includes an opening portion  2  having an opening O, a corrugation portion  3  having an convexoconcave  31 , a planar portion  4 B having one planar surface  40 B, and an attachment portion  5 . 
     The planar portion  4 B includes the planar surface  40 B, which is generally formed in an annular shape, and rising portions  44 , which are arranged across the planar surface  40 B in the radial direction. As illustrated in cross-section in  FIG. 9 , the planar surface  40 B is arranged on one side (upper side) in the thickness direction beyond the attachment portion  5 . 
     As with Example 1, the aforementioned configuration suppresses damage to the oscillatory system due to an excessive input signal and enables an increase in efficiency of the speaker apparatus. 
     Furthermore, the planar portion  4 B having one planar surface  40 B can have a simple configuration as compared to the planar portion  4 A having the plurality of planar surfaces  40  according to Example 1. 
     In addition, the present invention is not limited to Examples 1 and 2, but includes other configurations or the like that can achieve the object of the present invention. Variations or the like described below are included in the present invention. 
     For example, in Example 1 above, the plurality of planar surfaces  40  include the first planar surface  41 , which is arranged on one side in the thickness direction beyond the attachment portion  5  and the second planar surface  42 , which is arranged on the other side. However, the plurality of planar surfaces may include three or more types of planar surfaces arranged at different heights in the thickness direction. Furthermore, it is sufficient that the plurality of planar surfaces is extended substantially parallel to the attachment portion at a height in the thickness direction different from that of the attachment portion. For example, all the planar surfaces may be arranged either on one side or on the other side beyond the attachment portion. 
     Furthermore, in Example 1 above, 16 planar surfaces  40  (eight first planar surfaces  41  and eight second planar surfaces  42 ) have eight-fold rotational symmetry. However, when the plurality of planar surfaces have two- or more-fold rotational symmetry, the same effect as Example 1 above can be provided. Furthermore, for example, when the planar portion is sufficiently formed to hardly deform and partial deformation of the damper is suppressed, the plurality of planar surfaces may be formed asymmetrically. 
     In addition, the best configuration and method for carrying out the present invention are disclosed in the aforementioned description. However, the present invention is not limited thereto. In short, although the present invention is basically particularly illustrated and described with respect to particular embodiments, those skilled in the art can add a variety of variations with respect to the shape, the material, the quantity, and the other detailed configurations with regard to the aforementioned embodiments without departing from the technical idea and the scope of the object of the present invention. Accordingly, the descriptions that limit the shape, the material or the like disclosed above are exemplary descriptions for the sake of easy understanding of the present invention, but do not limit the present invention. Therefore, the descriptions of the names of members free of apart or the whole of the limitations regarding the shape, the material or the like are included in the present invention. 
     REFERENCE SIGNS LIST 
     
         
           1 A,  1 B damper 
           2  opening portion 
           3  corrugation portion 
           4 A,  4 B planar portion 
           5  attachment portion 
           31  convexoconcave 
           40 A,  40 B planar surface 
           41  first planar surface 
           42  second planar surface 
           43  connection 
         O opening