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JP2005203832

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JP2005203832
PROBLEM TO BE SOLVED: To provide an electro-acoustic transducer capable of stably obtaining
high sound quality without variation by simple work without eliminating peak dip on frequency
characteristics and without cost increase. SOLUTION: A concave portion (12A to 12K) and a
convex portion (11A to 11L) whose cross-sectional shape in the short direction is substantially
arc-shaped are alternately continued in a longitudinal direction on a substantially elongated
circular diaphragm (1). Of the concave portions (12A to 12K) and the convex portions (11A to
11L), and the ratio α of the widthwise direction (W) of the elongated circle to the longitudinal
direction length (L) of the elongated circle L was set to 1.0 ≦ α. Furthermore, α was set in the
range of 1.5 ≦ α ≦ 2.5. [Selected figure] Figure 1
Electro-acoustic transducer
[0001]
The present invention relates to an electroacoustic transducer, and more particularly to a narrow
(elongated) shaped speaker.
[0002]
For example, a speaker unit mounted on a television set is usually disposed on both sides of the
screen so as to obtain an optimum sound effect.
On the other hand, with TV sets, it has become a market requirement to make the set outer shape
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as small as possible with the increase in screen size and width, and as far as possible the width of
the speaker unit while pursuing high sound quality. It is required to reduce the size. In order to
meet the demand, various speaker units having a narrow width such as a square or an oval have
been provided. As an example of such a narrow-structure speaker, there is a speaker described in
the related art section of Patent Document 1.
[0003]
Furthermore, the invention described in Patent Document 1 provides a speaker (electro-acoustic
transducer) that solves the sound quality deterioration due to peak dip that occurs in a general
narrow-width speaker. Specifically, in a speaker having a narrow structure, since a narrow
diaphragm is driven by an elongated voice coil having a major axis and a minor axis, split
resonance in the long axis direction is easily excited. As a result, peak dips occur on the
reproduced sound pressure frequency characteristics in the middle to high tone band, resulting
in deterioration of the sound quality.
[0004]
In order to solve this, the electro-acoustic transducer in the invention described in the above
document is one in which a reinforcing agent is filled in a predetermined portion of the groove
portion surrounding the diaphragm (see, for example, paragraph 0035 of Patent Document 1). As
a result, the vibration mode (refer to FIG. 14 of Patent Document 1) of the bending wave
conventionally generated in the diaphragm is eliminated, and the peak dip (figure around 6 kHz)
of the middle to high tone band (approximately 6 kHz) generated notably by the vibration mode.
5) can be suppressed and good frequency characteristics can be obtained. JP 2002-325294 A
[0005]
However, the filling of the above-mentioned reinforcing agent has the following problems. (A)
The work process and man-hours for filling the reinforcing agent are increased. In addition, cost
increases occur due to the increase in the number of steps and the number of steps. In addition,
the cost increases due to the reinforcing agent itself. (B) It is necessary to accurately adjust the
concentration of the reinforcing agent and the filling position, which makes the operation
difficult and complicated. (C) Dispersion of frequency characteristics occurs in mass production
due to dispersion of coating amount and position. Therefore, it is not easy to maintain high sound
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quality.
[0006]
Therefore, the problem to be solved by the present invention is that the peak-dip is eliminated
without filling the reinforcing agent, and the cost does not increase, and an electroacoustic
transducer capable of stably obtaining high-quality sound without variation by easy operation. To
provide.
[0007]
In order to solve the above problems, the present invention has the following configuration as a
means.
That is, the invention according to claim 1 is a diaphragm having a substantially elongated
circular shape, and the cross-sectional shape in the short direction of the concave portion (12A to
12K) and the convex portion (11A to 11L) having a substantially arc shape are longitudinal
directions. The diaphragm (1) formed alternately and continuously, and an elongated external
shape larger than the diaphragm (1), the diaphragm (1) being disposed substantially at the center
of the diaphragm And an approximately frame-like frame surrounding the diaphragm (1), the
diaphragm (1) being supported via the edge so as to be free from vibration with respect to the
frame In the electro-acoustic transducer, the width (W) in the short direction and the length (L) in
the longitudinal direction of each of the concave portions (12A to 12K) and the convex portions
(11A to 11L) have a ratio α If the width W and the length L are 1.0 ≦ α when W / L An
electric-acoustic transducer (10) to symptoms. The invention according to claim 2 is the electroacoustic transducer (10) according to claim 1, characterized in that the ratio α is 1.5 ≦ α ≦
2.5.
[0008]
According to the present invention, it is possible to eliminate the peak dip without increasing the
cost and stably obtain high-quality sound without variation.
[0009]
An embodiment of the present invention will be described by means of a preferred embodiment
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with reference to FIGS.
FIG. 1 is a view showing an embodiment of the electro-acoustic transducer of the present
invention, FIG. 2 is a perspective view showing an essential part of the embodiment of the
electro-acoustic transducer of the present invention, and FIG. FIG. 4 is a perspective view
illustrating a voice coil in the embodiment of the electroacoustic transducer, and FIG. 4 is a graph
showing frequency response characteristics in the embodiment of the electroacoustic transducer
of the present invention.
[0010]
First, a specific configuration will be described mainly using FIG. 1 and FIG. Fig.1 (a) is the top
view, FIG.1 (b) is a half cross section in the AA line of FIG. 1 (a). FIG. 2 is a perspective view of a
diaphragm (including an edge) of the electro-acoustic transducer of the embodiment. This
diaphragm shows another example different from the diaphragm shown in FIG. 1 in the number
of concave portions and convex portions described later. The electro-acoustic transducer 10 is
configured to include a diaphragm 1, an edge 2 and a frame 3, which will be described in detail
below.
[0011]
In FIGS. 1 (a), (b) and FIG. 2, the diaphragm 1 has a long diameter and a short diameter, and is a
long circle consisting of a long side facing in parallel and a substantially arc-like portion
connecting its ends. Shaped members. The edge 2 is a member joined to the outer peripheral
portion (flanged portion 1 B described later) of the diaphragm 1 to hold the diaphragm 1 so as to
be able to vibrate with respect to the frame 3. It is a frame-like member which has unevenness in
part. The frame 3 is a substantially frame-shaped support for supporting the respective members,
and the long and short frame portions and the outer periphery of the edge 2 are joined to
support the edge 2.
[0012]
A track type voice coil bobbin 4 as shown in FIG. 3 is fixed to the lower surface side of the
diaphragm 1. The voice coil 5 is wound around the outer peripheral surface of the voice coil
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bobbin 4. The voice coil bobbin 4 is suspended in the magnetic gap G of the magnetic circuit, and
generates a driving force by the audio signal current and the magnetic flux.
[0013]
A magnetic circuit is attached to the inside of the frame 3. This magnetic circuit comprises a Ushaped yoke 6 made of iron, a magnet 7 fixed to the inside of the yoke 6, and a main vibrating
portion (generally a recessed convex portion of the diaphragm 1 at the tip of the magnet 7).
Range) and the pole piece 8 provided so as to face 1A.
[0014]
Next, the diaphragm 1 will be described in detail. As described above, the diaphragm 1 is a
substantially elongated round member having a major axis and a minor axis, the long sides facing
each other in parallel, and the diaphragm 1 is formed on the main vibrating portion 1A having an
uneven shape and the periphery thereof. And the flange portion 1B. The diaphragm 1 is formed
of a polyimide (PI) film so as to endure heat generation during operation of the voice coil 5 and
also has excellent mechanical characteristics as a diaphragm.
[0015]
In the main vibration portion 1A, a concave portion and a convex portion having concavities and
convexities in the vibration direction V and having a substantially arc-shaped cross section in the
minor axis direction are continuously formed in the major axis direction. That is, convex portions
11A to 11L and concave portions 12A to 12K which are alternately continued are formed.
[0016]
Next, the groove 23 will be described. It is a groove formed in a strip shape along the outer
peripheral portion (track) of the main vibration portion 1A of the diaphragm 1. The depth of the
groove 23 is shallower than the position of the voice coil 5 wound around the outer peripheral
surface of the voice coil bobbin 4. Further, the width Wm of the groove portion 23 is set to about
the magnetic gap Gp so as not to contact the magnetic circuit portion by the vibration of the
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vibration system. And this groove part 23 is shape ¦ molded by a metal mold ¦ die, and the
required surface precision is fully ensured.
[0017]
The specific configuration of the track type voice coil bobbin 4 fixed to the lower surface side of
the diaphragm 1 will be described with reference to FIG. As shown to this figure, the voice coil
bobbin 4 is formed so that the planar shape seen from the vibration direction of the diaphragm 1
may have a major axis and a minor axis. In addition, a part thereof has linear portions parallel to
each other in the major axis direction of the diaphragm 1. The voice coil bobbin 4 is divided into
two parts (41, 42) along the major axis direction of the diaphragm 1 in the form part to which
the wire is to be wound, and the divided parts are joined in the minor axis direction, and a beam
as a reinforcing part 13 is formed. On the other hand, a band 15 made of kraft paper used as
reinforcing paper is wound around the outer peripheral surface of the voice coil bobbin 4. The
voice coil 5 is wound around the outer peripheral surface of the band 15.
[0018]
The voice coil bobbin 4 configured in this manner is formed smaller than the inner dimension of
the groove portion 23. Also, the groove depth is set so that the voice coil 5 and the groove 23 do
not come in contact with each other.
[0019]
Now, since the present invention is characterized in particular by the diaphragm 1, it will be
described in detail below. In the diaphragm 1 of the embodiment described above, the ratio α of
the longitudinal length L of each of the recess and the convex portion to the length L (the width)
of each short direction is 1.0 ≦ α (where α It is as = W / L). The longitudinal length L is a
dimension set equal to each of the concave portions 12A to 12K and the convex portions 11A to
11L other than the central concave portion 12F and the convex portions 11G and 11F on both
sides thereof.
[0020]
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The present inventors have found that by setting the ratio of W and L in this manner, it is
possible to effectively suppress the occurrence of peak dip. The most desirable numerical range
of the ratio α is 1.5 to 2.5, and by setting the ratio α to this numerical range, the occurrence of
peak dip can be completely eliminated.
[0021]
FIG. 4 shows the frequency response characteristic when the ratio α is 2.0, which is the center
value of the range. Specifically, W = 7 mm and L = 3.5 mm. As apparent from this figure, high
frequency sound can be obtained because no peak dip occurs in the frequency response
characteristic.
[0022]
Of course, it is preferable to make the longitudinal length L equal in all the recesses and
projections, but if the length LA of the main vibrating portion 1A, the ratio α described above,
and the number of projections and recesses can not be equal, As described above, by setting the
dimensions by changing the length in the longitudinal direction of the concave portion (convex
portion) at the center in the longitudinal direction and the convex portions (concave portions)
adjacent thereto, the peak dip is hardly affected on the frequency response characteristics. Can
be eliminated. Further, this effect depends only on the value of α, and is not influenced by the
length LA of the main vibration portion 1A or the degree of unevenness of the concave and
convex portions.
[0023]
The relationship between the α value and the above-described effect is shown in Table 1 by ○
when there is an effect of suppressing peak dip, ◎ when there is an effect of eliminating, and x
when there is no effect of suppressing peak dip.
[0024]
[0025]
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In the most desirable configuration described above, if the slope of the portion connecting the
recess and the protrusion is steep and the length in the longitudinal direction is sufficiently small,
the number N of the recess and the protrusion can be set as follows.
The widthwise width (width of main vibration portion 1A) of concave and convex portions: W
longitudinal length of each of concave and convex portions: L ratio α = W / L (1.5 ≦ α ≦ 2. 5)
Length of main vibration portion 1A: LA Number of convex portions: Nt (Nt is a natural number)
Number of concave portions: No (No is a natural number) Number of concave portions and
convex portions: N (N = Nt + No) LA LA / L = LA / (W / α) = α * LA / W (where 1.5 ≦ α ≦ 2.5)
(1)
By setting the number N as in this equation (1), it is possible to obtain high sound quality by
eliminating the peak dip in the frequency response characteristic.
[0026]
Also, this simplifies the equation (1), such that 1.5 * LA / W ≦ N ≦ 2.5 * LA / W (where N is a
natural number) (2) Setting each value has the same meaning as forming the diaphragm 1. That
is, assuming that the width in the lateral direction of each of the recess and the protrusion is W,
the length in the longitudinal direction of the main vibrating portion 1A is LA, and the total
number of the recess and the protrusion is N, 1.5 * LA / W ≦ N ≦ 2.5 * LA / W (where N is a
natural number), and the width W and the length LA satisfy the conditions.
[0027]
Next, the operation of the above-described electroacoustic transducer 10 will be described. Since
a magnetic field is generated around the boil coil bobbin 4 by the magnet 7, when a drive current
flows through the boil coil 5 wound around the boil coil bobbin 4, an electromagnetic force
corresponding to this drive current is applied to the boil coil bobbin 4. The vibration acts on the
diaphragm 1 with the main vibrating portion 1A as a main component.
[0028]
In this operation, the surface accuracy of the groove portion 23 is well maintained as described
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above, and the diaphragm 1 is reliably supported by the upper end portion 4 a of the voice coil
bobbin 4, so the driving force acting on the voice coil bobbin 4 Is faithfully transmitted to the
diaphragm 1.
[0029]
On the other hand, as described above, the upper surface of the diaphragm 1 is a convex
substantially semi-cylindrical surface 11A to 11L projecting outward (in the direction of emitting
sound) and a concave substantially semi-cylindrical surface 12A to 12 Since the 12K and the 12K
are continuously and alternately arranged in the longitudinal direction, the generation of the
natural vibration component (a component that degrades the sound) of this portion is prevented
in a complementary manner.
And since the diaphragm 1 is formed in the shape mentioned above, the acoustic characteristic
which does not produce a peak dip is obtained.
[0030]
It is needless to say that the embodiment of the present invention is not limited to the abovedescribed configuration, and may be modified as long as the scope of the present invention is not
deviated.
[0031]
It is a figure which shows the Example of the electroacoustic transducer of this invention.
It is a perspective view which shows the principal part of the Example of the electroacoustic
transducer of this invention. It is a perspective view explaining the voice coil in the example of
the electroacoustic transducer of this invention. It is a graph which shows the frequency
response characteristic in the Example of the electroacoustic transducer of this invention. It is a
graph which shows the conventional frequency response characteristic. It is a figure explaining
the vibration mode of the conventional diaphragm.
Explanation of sign
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[0032]
DESCRIPTION OF SYMBOLS 1 diaphragm 1A main vibration part 1B flange part 2 edge 3 frame
4 voice coil bobbin 4a upper end part 5 voice coil 6 yoke 7 magnet 8 pole piece 10
electroacoustic transducer 11A-11L convex part 12A-12K concave part 15 band 23 groove part
G magnetic Air gap Gp Magnetic gap L, LA Length W, Wm Width α ratio
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