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JP2004048678

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DESCRIPTION JP2004048678
There is a method of enlarging an effective vibration diameter in order to improve the efficiency
of a speaker. Therefore, if the width of the edge is narrowed to make the cross-sectional shape
substantially hollow and semicircular, the linearity of the amplitude is significantly impaired. For
this reason, the maximum value of the amplitude and the maximum sound pressure do not
increase, and the sound quality is degraded. An edge (22) is formed into a substantially elliptical
hollow shape in cross section. The major axis of this ellipse is made parallel to the central axis of
the diaphragm 21, and the minor axis of the ellipse is set to be orthogonal to the central axis of
the diaphragm. When the elliptical edge of such a structure is used, the cross-sectional width of
the edge can be narrowed compared to the semicircular edge, and the amplitude linearity and the
amplitude maximum value are improved. [Selected figure] Figure 3
Speaker edge
[0001] The present invention relates to a speaker edge having a wide range of elastic
deformation of an edge which is a support system of a diaphragm. 2. Description of the Related
Art FIG. 1 is a cross-sectional view showing the structure of a conventional general speaker. The
speaker includes a diaphragm 1, an edge 2, a damper 3, a voice coil bobbin 4, a magnet 5, a
center pole 6, a plate 7, a voice coil 8, and a frame 10. The magnetic path of the magnetic flux
composed of the magnet 5, the center pole 6, the plate 7 and the magnetic gap 9 is referred to as
a magnetic circuit M. A specific radial direction of the diaphragm 1 is taken as an X axis, and a
central axis is taken as a Z axis. The edge 2 is an elastic member having an annular structure
when viewed from the + Z-axis direction. The edge 2 has a stick 2a, a stick 2b, and a curved
portion 2c. The edge 2 is fixed to the outer peripheral portion of the diaphragm 1 by the
adhesive seal 2a provided on the inner periphery thereof, and is fixed to the outer peripheral
portion of the frame 10 by the adhesive insulator 2b provided on the outer periphery. When the
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edge 2 is cut in a plane including the X-axis and the Z-axis, the cross-sectional shape of the
bending portion 2c is generally hollow and often curved in a semicircular shape. The magnetic
flux from the magnetic circuit M traverses the voice coil 8 at the magnetic gap 9. When a drive
current corresponding to an audio signal is applied to the voice coil 8, an electromagnetic force is
generated according to Fleming's law, and the voice coil bobbin 4 and the diaphragm 1 integrally
vibrate in the Z-axis direction. Thus, sound is emitted from the diaphragm 1 including the dome
portion. A 1 shown in the figure is an effective vibration diameter of the speaker, which is equal
to the distance between the center positions of the left and right curved portions 2 c located at
180 ° symmetrical positions. Therefore, the center of the curved portion 2 c of the edge 2 is
located at A1 / 2 from the center of the diaphragm 1. Generally, the effective area of the
diaphragm contributing to the sound pressure characteristics of the speaker is determined by the
effective vibration diameter A1. The damper 3 and the edge 2 are a support system which
elastically holds the diaphragm 1 in the Z direction and the radial direction with predetermined
positioning accuracy and restricts the amplitude of the vertical vibration of the diaphragm 1 and
the voice coil bobbin 4. is there. The outer periphery of the edge 2 is fixed to the frame 10 using
a glue 2b. The maximum amplitude value and amplitude linearity of the vertical vibration of the
diaphragm 1 are determined by the elastic characteristics and the viscosity characteristics
(dumping characteristics) which are the characteristics of the damper 3 and the edge 2. The
efficiency of the speaker is higher as the effective vibration diameter A1 is larger. In order to
improve the efficiency of the speaker, it is necessary to narrow the radial width (hereinafter
referred to as “cross-sectional width”) of the curved portion 2 c of the edge 2 in order to
expand the aperture of the diaphragm while maintaining the same outer diameter. There is.
[Patent Document 1] JP-A-61-276499 [Patent Document 2] Patent No. 3127669. Problem to be
Solved by the Invention [0010] The cross-sectional shape of the curved portion is a semicircular
edge In 2, the width of the edge can be narrowed by reducing the radius of curvature of the
curved portion. However, in this method, the edge 2 follows the amplitude of the vertical
vibration of the diaphragm 1 and the voice coil bobbin 4 and is less likely to be deformed. In this
case, the maximum values of the amplitudes of the edge 2 and the diaphragm 1 become small,
and the amplitude linearity in elastic deformation of the edge is significantly impaired. At the
same time, the stiffness of the edge 2 also increases, so the maximum sound pressure of the
speaker does not increase and the minimum resonance frequency of the speaker increases. This
makes it difficult to reproduce the low frequency band and the sound quality is degraded. The
present invention has been made in view of such conventional problems, and it is an elastic
deformation of an edge which is a supporting system of a diaphragm, without expanding the
outer diameter of the diaphragm and the sectional width of the edge. It is an object of the present
invention to realize a speaker edge whose range is broadened. The invention according to claim 1
of the present application is used for a speaker having a diaphragm and a frame, the edge outer
periphery is fixed to the frame, and the edge inner periphery is the outer periphery of the
diaphragm A speaker edge of an annular structure in which the curved portion is formed along
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the outer periphery of the diaphragm, and the cross-sectional shape of the curved portion along
the radial direction of the diaphragm is a hollow substantially semi-elliptical shape And the ratio
of the width along the minor axis of the ellipse to the height along the major axis is not less than
1.0: 1.14, and the major axis of the ellipse is parallel to the central axis of the diaphragm; The
minor axis is set in a direction orthogonal to the central axis of the diaphragm. According to a
second aspect of the present invention, in the speaker edge of the first aspect, a point on the
inner circumference of the curved portion is an inner circumference point, which is a position
that forms a predetermined central angle with the inner circumference point. When a point on
the outer periphery of the curved portion is taken as an outer peripheral point, a plurality of
grooves connecting the pair of inner and outer peripheral points are formed at equal intervals
along the annular position of the curved portion, and the groove has a cross section It is
characterized in that it is formed by plastic deformation of the material of the edge so as to be
either V-shaped or U-shaped. According to a third aspect of the present invention, in the speaker
edge of the second aspect, a first straight line connecting the center of the diaphragm and the
inner circumferential point, and a second straight line connecting the center and the outer
circumferential point It is characterized in that the central angle with the straight line is in the
range of 0 ° or more and 40 ° or less.
According to a fourth aspect of the present invention, in the speaker edge of the second aspect,
the groove has a radius of curvature in a range of 0.1 (mm) to 0.3 (mm) at the corner of the
cross-sectional shape. It is characterized by being inside. BEST MODE FOR CARRYING OUT THE
INVENTION A speaker edge according to an embodiment of the present invention will be
described with reference to FIGS. The same components as those in the conventional speaker
shown in FIG. First Embodiment A speaker edge in a first embodiment of the present invention
will be described with reference to the drawings. FIG. 2 is a plan view showing a planar structure
of the speaker edge and the diaphragm in the first embodiment of the present invention, and FIG.
3 is a cross-sectional view showing a main part structure of the speaker edge. FIG. 4 is a crosssectional view showing a main part structure of a speaker in which the speaker edge of the
present embodiment is used. The components of the speaker other than the edge 22 in FIG. 4 are
the same as those shown in FIG. The speaker shown in FIG. 4 is characterized in that the
structure of the edge of the components shown in FIG. 1 is changed. As shown in FIG. 3, the edge
22 is formed by integrally forming an inner attachment portion 22 a, a curved portion 22 c, and
an outer attachment portion 22 b in an annular shape. A2 in the figure indicates the effective
vibration diameter of the speaker. The effective vibration diameter A2 is the distance between
the central positions of the curved portions 22c located at 180 ° symmetrical positions of the
edge 22. Therefore, the top of the bending portion 22c is located at A2 / 2 from the center of the
diaphragm 21. B in the figure is called the cross-sectional width of the curved portion 22c. Z
indicates the vibration direction of the diaphragm 21. The edge 22 of the present embodiment
has an annular structure in which the curved portion 22 c makes a round along the outer
periphery of the diaphragm 21. The cross-sectional shape of the curved portion 22c along the
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radial direction of the diaphragm 21 is a hollow substantially semielliptical shape, and the major
axis of the ellipse is parallel to the central axis of the diaphragm 21 and the width along the
minor axis of the ellipse is vibration. It is characterized in that it is set in the direction orthogonal
to the central axis of the plate 21. Such an edge is called an elliptical edge. The height along the
major axis, that is, the height from the vertex to the lower surface of the adhesive 22b is height F,
and the width along the minor diameter, that is, the width from the vertex to the left end of the
adhesive 22b is G. The adhesive plate 22a is fixed to the outer peripheral portion of the
diaphragm 21, and the adhesive plate 22b is fixed to the frame, whereby the diaphragm 21 is
held so as to be able to vibrate. The operation of a speaker having such an elliptical edge will be
described.
When a drive current corresponding to an audio signal is applied to the voice coil of the speaker,
the diaphragm 21 fixed to the voice coil bobbin vibrates in the Z direction. The edge 22 is
attached to the outer peripheral portion of the diaphragm 21 and fixed thereto via the insulator
22a, and the attachment 22b of the edge 22 supports the frame 10 to restrict the vibration of the
diaphragm 21. That is, if the edge 22 does not exist, the diaphragm 21 does not always vibrate in
the Z direction in the normal posture. As the drive current of the voice coil 8 is increased, the
vibration amplitude of the diaphragm 21 is increased. At this time, the amount of deformation of
the elliptical edge also increases due to the extension of the curved portion 22c. When the
amount of deformation of the bending portion 22c reaches a limit, the diaphragm 21 can not
vibrate at a further amplitude. At this time, the amplitude in the Z direction of the diaphragm 21
is referred to as an amplitude maximum value. By making the cross-sectional shape of the curved
portion 22c into a hollow, substantially elliptical shape, the cross-sectional width B of the curved
portion 22c can be reached without exceeding the limit of elastic deformation and without
changing the outer diameter (A2 + B) of the edge 22. To reduce the effective vibration diameter
A2 of the speaker. Since the efficiency of the speaker is proportional to the effective vibration
area, the efficiency of the speaker can be improved by enlarging the effective vibration diameter
A2. FIG. 5 is a characteristic diagram showing the relationship between the force applied to the
edge and the displacement. The horizontal axis is a force [N] in the Z direction, and the vertical
axis is a displacement [m] in the Z direction. In this figure, the cross-sectional width B of the
curved portion 22c is the same, and the cross-sectional shape of the curved portion is a
semicircular conventional edge (hereinafter referred to as semicircular edge J0), and the force
and displacement of the elliptical edge J1 according to the present embodiment The relationship
of is shown in the figure. As compared with the semicircular edge J0, the amplitude maximum
value of the elliptical edge J1 becomes significantly larger. This is because when the curved
portion has an elliptical shape, the cross-sectional length along the material surface of the curved
portion becomes long, so the amount of expansion at the time of deformation can be increased.
In the case where the cross-sectional shape of the curved portion is semicircular, as described
above, when the cross-sectional width B of the curved portion is further narrowed to improve the
efficiency of the speaker, the maximum amplitude value is suppressed. In this case, the maximum
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sound pressure is lost, and the performance as a speaker is degraded. By making the crosssectional shape of the curved portion elliptical, it is possible to improve the efficiency of the
speaker without losing the maximum amplitude and the maximum sound pressure. FIG. 6 is an
explanatory view showing stiffness characteristics of the edge and the damper.
The horizontal axis indicates the displacement of the edge or damper in the Z direction [m], and
the vertical axis indicates the stiffness [N / m]. This figure shows the stiffness characteristics of
the elliptical edge J1, the stiffness characteristics of the semicircular edge J0 having the same
cross-sectional width, and the stiffness characteristics of the very general corrugated damper D0.
In the semicircular edge J0 and the damper D0, the stiffness increases as the vibration amplitude
increases. That is, the semicircular edge J0 and the damper D0 do not easily move as a support
member of the diaphragm, and the vibration amplitude is regulated. However, the characteristics
of the elliptical edge J1 are opposite to the characteristics of the semicircular edge J0 and the
characteristics of the damper D0, and the smaller the vibration amplitude, the harder it is to
move and the stiffness toward the maximum value of the vibration amplitude It tends to be
smaller. That is, the elliptical edge J1 is easy to move in the region where the vibration amplitude
is large. The stiffness characteristics of the entire vibration system are determined by the
combined characteristics of the edge and the damper. Therefore, the linearity of the overall
stiffness can be improved by using the elliptical edge J1 having the stiffness characteristic
opposite to that of the damper. As a result, the improvement of the amplitude linearity of the
speaker and the reduction of distortion can be realized. Therefore, in the state where the effective
vibration diameter is held within the allowable range, the effect of improving the sound quality as
the speaker can be obtained. FIG. 7 is an explanatory view showing the stiffness characteristics of
an elliptical edge when the height along the major axis of the curved portion 22 c is F and the
width along the minor axis is G. The vertical axis in FIG. 7 indicates the stiffness [N / m], and the
horizontal axis indicates the edge displacement in the Z direction [m]. In the case of an elliptical
edge having the same cross-sectional width B as the curved portion, the stiffness characteristics
when the ratio of the width G along the minor axis to the height F along the major axis is
changed is shown. In the figure, H1 is when G: F is 3.5: 3.8, H2 is when G: F is 3.5: 4.0, and H3 is
when G: F is 3.5: 4.5 H4 shows the stiffness characteristics when G: F is 3.5: 5.0. In order to
improve the amplitude linearity of the entire speaker, the stiffness characteristics of the elliptical
edge need to be reversed to the stiffness characteristics of the damper. It has such a
characteristic in the case of 3.5: 4.0 or more of H2, ie, in the case of H2, H3, and H4. Accordingly,
the ratio of the width G to the height F is 3.5: 4.0 or more, that is, 1.0: 1.14 or more. According to
the speaker edge having the above-described structure, it is possible to narrow the crosssectional width of the curved portion in the speaker having the same diameter, to enlarge the
effective vibration diameter, and to improve the efficiency of the speaker.
This makes it possible to improve the sound quality by improving the linearity of the amplitude
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of the speaker without losing the maximum value of the amplitude. Second Embodiment Next, a
speaker edge in a second embodiment of the present invention will be described. FIG. 8 is a plan
view showing the structure of the speaker edge and the diaphragm in the second embodiment.
FIG. 9 shows a main part structure of the speaker edge in the present embodiment, and is a
cross-sectional view along the groove. FIG. 10 is a cross-sectional view of the speaker edge when
it is cut in the direction perpendicular to the groove. The speaker edge of the present
embodiment is characterized in that in addition to the elliptical edge of the first embodiment, a
large number of grooves are provided in the curved portion in the tangential direction of the
diaphragm. The other configuration is the same as that of the first embodiment. As shown in FIG.
8, a grooved edge 32 is joined to the outer peripheral portion of the diaphragm 31 of this
speaker. Similar to the first embodiment, the edge 32 according to the present embodiment has
the sticking glue 32a, the sticking glue 32b, and the bending part 32c, and the cross section of
the bending part 32c along the radial direction of the diaphragm 31 is substantially hollow. It is
semi-elliptical. The major axis of the ellipse is parallel to the central axis of the diaphragm 31,
and the minor axis of the ellipse is set to be orthogonal to the central axis of the diaphragm 31.
As shown in FIG. 8, the center of the diaphragm 31 is O, one point on the inner periphery of the
bending portion 32c is P1 (first point), and one point on the outer periphery of the bending
portion 32c is P2 (second Point) A straight line connecting the center O and the point P1 is L1, a
straight line connecting the center O and the point P2 is L2, and an angle formed by the straight
lines L1 and L2 is α. Next, the groove 33 is formed on the straight line L3 connecting the points
P1 and P2 by plastically deforming the material of the edge. A plurality of the grooves 33 are
preferably arranged at equal intervals along the outer peripheral portion of the diaphragm 31.
The angle α indicating the direction of the groove 33 varies depending on the outer diameter of
the diaphragm and the number of the grooves 33, but is in the range of 0 ° to 40 °. The crosssectional shape of the groove 33 in the case of cutting along the normal line L4 orthogonal to the
straight line L3 is U-shaped or V-shaped as shown in FIG. When the groove 33 is cut along the
straight line L3 of FIG. 8, the corner 33a of the groove 33 matches the contour of the curved
portion 32c of the edge 32, as shown in FIG. The bottom 33 b is a valley of the groove 33. In the
cross-sectional view of the edge 32 shown in FIG. 10, when the cross-sectional shape of the
groove 33 is U-shaped, the radius of curvature of the corner 33 a and the bottom 33 b of the
groove 32 is indicated by symbol R.
The radius of curvature of the bottom 33b of the groove 33 is R1, and the radius of curvature of
the corner 33a is R2, R3. The groove 33 is integrally formed simultaneously with the curved
portion 32 c by plastic deformation of the material of the edge 32. The forming method differs
depending on the material. For example, in the case of a rubber sheet, a sheet material such as a
cloth material filled with rubber, or a film material made of resin, pressure molding using a mold
is used. When the material of the edge is resin, melt injection molding is used. The radius of
curvature of these materials is set to a value that can cause elastic fatigue due to repeated local
stress of the material and prevent breakage at this part. The values of the radii of curvature R1,
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R2 and R3 are set, for example, in the range of 0.1 (mm) to 0.3 (mm 2) in consideration of the
cross-sectional width of the curved portion and the thickness of the material. Such an R portion is
also referred to as chamfering. As in the case of the first embodiment, by making the crosssectional shape of the curved portion of the edge 32 substantially hollow, it is possible to bend
without changing the outer diameter of the edge without exceeding the limit of elastic
deformation. The cross-sectional width B of the portion can be reduced, and the effective
vibration diameter A2 of the diaphragm can be enlarged. Since the efficiency of the speaker is
proportional to the effective vibration area determined by the effective vibration diameter, the
efficiency of the speaker is improved. FIG. 11 is an explanatory view comparing stiffness
characteristics in the case where there is a groove and in the case where there is no groove at an
elliptical edge. The horizontal axis represents displacement in the Z direction [m], and the vertical
axis represents stiffness [N / m]. K1 is the characteristic of the elliptical edge when there is no
groove. K2 is the characteristic of the elliptical edge when there is a groove. A region L indicates
a range in which the stiffness characteristic changes rapidly at an elliptical edge having no
groove. This rapid change occurs when the amount of deformation of the curved portion reaches
a limit when the force N in the Z direction is increased, and finally the diaphragm itself fixed to
the inner peripheral portion of the edge is deformed. Therefore, the maximum value of the
amplitude is represented by the value at the left end point M1 of the region L, and in this
example, the maximum value of the amplitude is 0.002 m. By providing the groove 33 having
such a structure, the material of the groove 33 can be expanded in the direction of the normal L4
of the groove, and the amount of elastic deformation of the curved portion 32c can be increased.
For this reason, the tension phenomenon can be alleviated, and the maximum value of the
amplitude can be expanded from the point M1 to the point M2 as shown in FIG. In this example,
the displacement at the point M2 has a value close to 0.003 m. That is, the half amplitude is
further increased by about 1 mm. On the other hand, when the grooveless elliptical edge as
shown in FIG. 3 is used to expand the effective vibration diameter, the lowest resonance
frequency of the speaker is increased.
By providing grooves 33 in the elliptical edge to reduce the lowest resonance frequency, the
increase in stiffness of the edge 32 can be suppressed. As shown by the characteristic K 2 in FIG.
11, the grooved elliptical edge has a wide range in which the stiffness does not change. For this
reason, an edge with extremely excellent linearity can be obtained. Thus, the stiffness
characteristics of the entire speaker using the grooved elliptical edge are significantly improved
over the conventional speaker using the semicircular edge. Although the number of grooves 33 is
illustrated as 36 in FIG. 8, the number of grooves may be arbitrary. The designer or manufacturer
of the speaker can select the number and shape of the grooves and the arrangement method of
the grooves in consideration of ease of shaping, amplitude linearity, amplitude maximum value,
and minimum resonance frequency of the speaker. FIG. 12 is an explanatory view showing the
relationship between the angle α, the inner diameter N1 of the bending portion, and the outer
diameter N2 of the bending portion. The condition that the value of α is the largest is when the
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center line of the groove 33 is in contact with the inner periphery of the curved portion. In this
state, α is expressed by the following equation (1). α = cos <−1> (N1 / N2) (1) In a general
speaker with a diameter of 80 mm to 300 mm, the cross-sectional width B of the curved portion
is 20 mm or less. FIG. 13 changes the inner diameter (denoted as edge inner diameter) N1 of the
curved portion and the outer diameter (denoted as edge outer diameter) N2 of the curved
portion, with the cross-sectional width of the curved portion (denoted as edge width) being 5 to
20 mm. It shows the relationship between the value of the angle α and the edge width. A
speaker in which α exceeds 40 ° is a special one having an extremely large edge width, which
deviates from the object of the present invention of enlarging the effective diameter of the
vibration to increase the efficiency. Therefore, the range of the angle α for forming the groove is
in the range of 0 ° to 40 °. FIG. 14 shows an example of the change of the lowest resonance
frequency due to the diaphragm and the edge in the case where the curvature radius R of
chamfering is changed from 0.0 mm to 0.4 mm and in the case where there is no groove in each
part of the groove. FIG. According to this figure, when the curvature radius R of chamfering is 0
mm (without chamfering), the minimum resonance frequency is higher than that without the
groove. That is, without chamfering, the stiffness of the curved portion is increased, the
movement is difficult, and the maximum value of the amplitude is suppressed. When the
curvature radius R of chamfering is 0.2 mm, the lowest resonance frequency is the lowest in FIG.
That is, the stiffness of the curved portion at the edge is minimized, and the curved portion is
easy to move.
When the curvature radius R of chamfering is 0.4 mm, the minimum resonance frequency rises
again more than in the case where there is no groove, and the curved portion becomes less likely
to move. Since the purpose of providing the groove 33 is to expand the maximum value of the
amplitude and to reduce the stiffness, the effect can be obtained when the radius of curvature R
is in the range of 0.1 mm to 0.3 mm. Further, in actual edge molding, it is substantially difficult to
form the groove 33 without chamfering, since a composite material such as soft cloth or rubber
is often used. Chamfering is inevitably formed also from such conditions. Third Embodiment
Next, a speaker edge in a third embodiment of the present invention will be described. FIG. 15 is
a plan view showing the structure of the speaker edge and the diaphragm in the third
embodiment. The speaker edge of the present embodiment is characterized in that in addition to
the elliptical edge of the first embodiment, a large number of grooves are provided on the edge,
and these grooves are arranged radially. The other configuration is the same as that of the first
embodiment. FIG. 16 shows the main part structure of the speaker edge in the present
embodiment, and is a cross-sectional view in the case of being cut along the groove. FIG. 17 is a
cross-sectional view of the speaker edge when it is cut in the direction perpendicular to the
groove. This speaker is the one in which the shape of the edge is further changed among the
structural members shown in FIG. As shown in FIG. 15, the grooved edge 42 is joined to the outer
peripheral portion of the diaphragm 41. The edge 42 has, as shown in FIG. 16, a sticking portion
42a, a sticking portion 42b, and a curved portion 42c, and the cross-sectional shape of the
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curved portion 42c is along the radial direction of the diaphragm 41 as in the first and second
embodiments. It is formed into a hollow substantially semi-elliptical shape. The major axis of the
ellipse is parallel to the central axis of the diaphragm 41, and the minor axis of the ellipse is set
to be orthogonal to the central axis of the diaphragm 41. As shown in FIG. 15, it is assumed that
the center of the diaphragm 41 is O, and the point at which the radial line from the center O
toward the outside of the diaphragm 41 intersects the inner periphery of the curved portion 42c
is Q1 (inner peripheral point). A point intersecting the outer periphery of the bending portion
42c is taken as Q2 (outer peripheral point). Next, along the straight line Q1-Q2, the groove 43 is
formed by plastic deformation of the material of the edge. The grooves 43 are arranged radially
along the outer peripheral portion of the diaphragm 41, preferably at equal intervals. The crosssectional shape of the groove 43 when cut along the straight line Q1-Q2 is as shown in FIG. 16,
the bottom of the groove 43 is indicated by 42d, and the corner of the edge 42 is indicated by
42e.
In addition, the paste line 42a is a paste line of the inner peripheral part of the curved part 42c,
and the paste line 42b is a paste line of an outer peripheral part of the curved part 42c. Next,
FIG. 17 shows a side view of the edge 42 including the cross section of the groove 43 when it is
cut along the straight line L5 orthogonal to the straight line Q1-Q2 of FIG. The cross-sectional
shape of the groove 43 is U-shaped or V-shaped. In the cross-sectional view of FIG. 17, the radius
of curvature of the corner and the bottom of the groove 43 when the cross-sectional shape of the
groove 43 is U-shaped is shown. The radius of curvature of the bottom of the groove 43 is R3
and the radius of curvature of the corner of the groove 43 is R4 and R5. The chamfered portion
having such a radius of curvature is set to prevent elastic fatigue due to the repetition of local
stress of the material as in the second embodiment, and to prevent breakage at this portion. The
values of the radius of curvature R3, R4 and R5 are set within the range of 0.1 (mm) to 0.3 (mm)
in the same manner as shown in FIG. 10 in consideration of the cross-sectional width of the
curved portion and the thickness of the material. Be done. Even in the speaker having such a
structure, the cross-sectional width B of the curved portion can be reduced without changing the
outer diameter of the edge by making the cross-sectional shape of the curved portion at the edge
42 hollow and substantially elliptical. The effective vibration diameter A2 of the diaphragm can
be enlarged. Since the efficiency of the speaker is proportional to the effective vibration area
determined by the effective vibration diameter, the efficiency of the speaker is improved. The
above effect is equivalent to that of the first embodiment. Further, by providing the groove 43,
the portion of the groove 43 can be expanded in the circumferential direction as the amount of
deformation of the edge 42 becomes larger. For this reason, it is possible to alleviate the tension
phenomenon and to enlarge the maximum value of the amplitude of the elliptical edge. Further,
as described above, when the grooveless elliptical edge is used to expand the effective vibration
diameter, the minimum resonance frequency of the speaker is increased. By providing such
grooves 43 in the elliptical edge, the stiffness of the elliptical edge can be significantly reduced.
Therefore, the groove 43 is an effective method for reducing the lowest resonance frequency of
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the vibration system. The above effects are equivalent to those of the second embodiment. FIG.
18 is an explanatory view comparing the stiffness characteristics of each edge. The horizontal
axis represents the displacement [m] in the Z direction, and the vertical axis represents the
stiffness [N / m]. In this figure, the stiffness characteristics of the non-grooved elliptical edge J1,
the stiffness characteristics of the grooved elliptical edge J2 of the second embodiment (angle α
= 10 °), and the stiffness characteristics of the grooved elliptical edge J3 of the third
embodiment are shown. It is shown.
From these characteristics, the difference between the stiffness characteristics at the edge of the
present embodiment in which grooves are radially provided with the same elliptical shape and
the stiffness characteristics of other elliptical edges can be seen. According to FIG. 18, at the edge
42 provided with the grooves 43 radially like the grooved elliptical edge J 3, the maximum
amplitude value is further increased. This method can be said to be effective when emphasizing
the expansion of the maximum value of the amplitude at the elliptical edge. Although the number
of grooves 43 provided radially in FIG. 15 is 36, it may be any number. Furthermore, in FIG. 16,
the cross-sectional shape of the bottom portion 42d of the groove 43 is substantially semielliptical, but this portion may be semi-circular. The designer and manufacturer of the speaker
can freely select the shape and arrangement of the groove in consideration of the ease of
molding of the material, the amplitude linearity, the maximum amplitude value, and the minimum
resonance frequency of the speaker. As described above, according to the grooved elliptical edge,
the stiffness of the edge when the amplitude is larger than that of the grooveless elliptical edge
can be reduced, and the elastic deformation range in the axial direction of the diaphragm can be
further expanded. In this way, at the narrow edge of the cross section of the curved portion, the
amplitude linearity is improved, the efficiency of the speaker is improved, the lowest resonance
frequency is lowered, the low frequency reproduction ability is enhanced, and the maximum
sound pressure is also expanded. Can. According to the speaker edge of the present invention, it
is possible to narrow the cross-sectional width of the edge of the speaker having the same
aperture, enlarge the effective vibration diameter, and improve the efficiency of the speaker. This
makes it possible to improve the sound quality by improving the linearity of the amplitude of the
speaker without losing the maximum value of the amplitude. Further, by providing a large
number of V-shaped or U-shaped grooves in the curved portion of the edge, the stiffness of the
edge at the time of large amplitude is reduced, and the elastic deformation range of the
diaphragm in the axial direction can be reduced. It can be further expanded. By doing this, it is
possible to improve the linearity of the amplitude and to improve the efficiency of the speaker
while lowering the lowest resonance frequency, to improve the low frequency reproduction
ability, and to expand the maximum sound pressure at the edge having a narrow cross section. it
can. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a main
part structure of a conventional speaker. FIG. 2 is a plan view of the speaker edge in the first
embodiment of the present invention. FIG. 3 is a cross-sectional view of main parts of the speaker
edge in the first embodiment. FIG. 4 is a cross-sectional view showing an essential structure of a
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speaker in which an elliptical edge according to Embodiment 1 is used.
FIG. 5 is a characteristic diagram showing the relationship between force and displacement at the
elliptical edge of the first embodiment and the conventional semicircular edge. FIG. 6 is a
characteristic diagram showing a relationship between displacement and stiffness in an elliptical
edge, a semicircular edge according to a conventional example, and a general damper in the first
embodiment. FIG. 7 is a characteristic diagram showing the relationship between displacement
and stiffness when the ratio of the major axis to the minor axis is changed in the elliptical edge
according to the first embodiment. FIG. 8 is a plan view of a speaker edge in a second
embodiment of the present invention. 9 is a cross-sectional view showing an essential structure
of a speaker edge in Embodiment 2. FIG. FIG. 10 is a cross-sectional view showing a main part
structure of a speaker edge in a second embodiment. 11 is a characteristic diagram showing a
relationship between displacement and stiffness depending on the presence or absence of a
groove in the speaker edge of Embodiment 2. FIG. 12 is an explanatory view showing a
relationship between a central angle α and an inner diameter and an outer diameter of a
bending portion in the speaker edge according to the second embodiment. FIG. FIG. 13 is a
diagram showing values of an angle α when the inner edge diameter and the outer edge
diameter are changed. FIG. 14 is an explanatory view showing a case of changing a chamfering
radius R of chamfering of a groove, a case without a groove, and a change of the lowest
resonance frequency with a curvature radius at a groove of an edge of an edge as a parameter.
FIG. 15 is a plan view of a speaker edge in a third embodiment of the present invention. FIG. 16
is a cross-sectional view showing a main part structure of a speaker edge in a third embodiment.
FIG. 17 is a cross-sectional view showing a main part structure of a speaker edge in a third
embodiment. FIG. 18 is a characteristic diagram showing the relationship between edge
displacement and stiffness in each embodiment. [Explanation of the code] 1, 21, 31, 41
diaphragm 2, 22, 32, 42 edge 3 damper 4 boss coil bobbin 5 magnet 6 center pole 7 plate 8
voice coil 9 magnetic gap 10 frame 22a, 22b, 32a, 32b, 42a, 42b Affixing sheath 22c, 32c, 42c
Curved part 33, 43 Groove 33b, 42e Bottom part 33a, 42d Corner part M Magnetic circuit
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