close

Вход

Забыли?

вход по аккаунту

?

JP2008109587

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
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
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2008109587
PROBLEM TO BE SOLVED: To suppress distortion of a voice coil bobbin generated near the high
frequency band limit frequency of a cone type dynamic speaker and improve the frequency
characteristic of the speaker. A voice coil bobbin is covered with a flat plate over the entire
opening of an end portion connected to a vibrator to prevent deformation of the voice coil
bobbin. As another means, a flat plate is attached to the vibrator immediately above the
connecting portion of the voice coil bobbin and the vibrator. [Selected figure] Figure 1
スピーカ
[0001]
The present invention relates to a speaker for sound reproduction, and more particularly to a
structure of a cone type dynamic speaker.
[0002]
The general structure of a conventional cone-type dynamic speaker will be described using FIG.
FIG. 6 is a longitudinal cross-sectional view of the cone-shaped dynamic speaker in the cone
diameter direction. Only basic structural members are shown, and additional parts are omitted. In
the figure, reference numeral 1 denotes a yoke of a magnetic body having a cross-sectional shape
of "字". A cylindrical protrusion 11 stands at the center of the yoke 1. The diameter of the top of
the projection 11 is made to be horizontally greater than the diameter of the base to form the
12-05-2019
1
magnetic pole 12. A ring-shaped magnet 2 is mounted on the outer periphery of the yoke 1 and
fixed to the yoke 1. A ring-shaped plate 3 made of a magnetic material is fixed on the top of the
magnet 2. The inner diameter of the plate 3 is smaller than the inner diameter of the magnet 2 to
form a narrow gap G between the plate 3 and the magnetic pole 12, and a strong magnetic field
is generated in the gap G. The width of the gap G is a width obtained by adding a play to the sum
of the thickness of the voice coil bobbin 7 described later and the thickness of the voice coil 10
wound thereon.
[0003]
A funnel-shaped frame 4 is made of metal, and a plate 3 and a block in which the magnet 2 and
the yoke 1 are integrated are attached to the lower opening. On the other hand, a cone-shaped
vibrator 5 having an outer diameter substantially equal to the diameter of the upper opening is
attached to the upper opening of the frame 4 and adhesively fixed to the frame 4 together with
the gasket 6 after positioning adjustment. In the lower part of the cone-shaped vibrator 5, a
circular hole substantially corresponding to the diameter of the voice coil bobbin 7 is opened.
[0004]
A voice coil bobbin 7 is made of a hard paper or the like and formed in a hollow cylindrical
shape. The voice coil 10 is wound on the voice coil bobbin 7. The position on the voice coil
bobbin 7 at which the voice coil 10 is wound is determined such that the substantially central
portion of the voice coil 10 is in the air gap G when the speaker assembly is completed.
[0005]
The diameter of the voice coil bobbin 7 is substantially equal to the diameter of the center of the
narrow annular gap G formed between the magnetic pole 12 of the yoke and the plate 3. The
voice coil bobbin 7 is inserted into the air gap, and the whole including the voice coil 10 is
positioned so as not to touch either the magnetic pole 12 or the plate 3, and the upper end is
fixed to the circular hole of the vibrator 5. Be done. That is, the voice coil bobbin 7 is suspended
in the air gap G.
[0006]
12-05-2019
2
In this state, when a voice current is supplied to the voice coil 10 wound around the voice coil
bobbin 7, the voice coil bobbin 7 moves up and down in the figure at right angles to the magnetic
field, and the vibrator vibrates accordingly. By creating a compressional wave in the air on the
front, you will be playing the sound. 8 is a wedge-shaped damper made of an elastic material, the
inner edge is fixed to the voice coil bobbin 7 and the outer edge is fixed to the frame 3 to support
the coil bobbin in a fixed position and to suppress excessive vertical movement of the coil bobbin
To work.
[0007]
A dust cap 9 is made of a dustproof material and is attached to the vibrator so as to cover the
upper space of the voice coil bobbin. This protects the drive unit of the speaker from dust in the
air, particularly dust that is easily adsorbed to a magnet such as iron powder. The dust cap 9 is
usually made of a lightweight material such as paper, cloth or the like because it has an influence
on the vibration of the vibrator if its mass is large, and is formed in a dome shape so as to
withstand the air pressure due to the vibration. . The structure and required properties of the
dust cap are described in Japanese Patent Application No. 3-345999. Japanese Patent
Application No. 3-345999
[0008]
In the cone type dynamic speaker having the above-mentioned structure, the acceleration of the
vertical movement generated in the voice coil bobbin 7 increases in proportion to the square of
the frequency of the voltage applied to the voice coil. When the frequency exceeds a certain
frequency, the rigidity of the bonding portion between the voice coil bobbin 7 and the vibrator 5
can not excite the total mass of the mass of the vibrator and the mass of air on the front of the
vibrator. This frequency is called a high frequency limit frequency, for example, about 3 KHz with
a standard speaker with an aperture of about 20 cm.
[0009]
Above the upper limit frequency, the vibrator 5 can not move sufficiently, and accordingly the
voice coil bobbin 7 freely moves in the direction of weak intensity, generating complicated
12-05-2019
3
pendulum motion and linear motion, The cylindrical shape of the voice coil bobbin 7 is distorted.
Also, even if the frequency before reaching the high frequency limit frequency, the same
phenomenon is likely to occur as the high frequency limit frequency is approached, and the
faithful reproduction of the original signal becomes difficult.
[0010]
The bobbin of the voice coil bobbin is usually formed on a cylinder of paper having a thickness of
about 0.2 mm. Therefore, it is conceivable to increase the thickness of the paper used or to
impregnate the resin in order to increase the strength. However, the voice coil bobbin 7 is
required to be as thin as possible and to reduce its mass in order to be sensitive to changes in the
original signal. Therefore, there is a limit to increasing the paper thickness to increase the
strength.
[0011]
The present invention provides a speaker which increases the strength of the voice coil bobbin 7
without changing the thickness of the voice coil bobbin 7 and reduces the distortion of the
bobbin due to the irregular vibration generated near the high frequency limit frequency.
Therefore, the circular opening near the portion of the voice coil bobbin 7 to be bonded to the
vibrator 5 is closed with a reinforcing flat plate over the entire surface to prevent distortion of
the voice coil bobbin and maintain the circular shape.
[0012]
By the means described above, the speaker of the present invention can minimize distortion
occurring in the voice coil bobbin and distortion accompanying the vibration as much as
possible, and can obtain good frequency characteristics. Furthermore, distortion generated in the
voice coil bobbin is effective in reducing breakage of the speaker due to a crack generated in the
bonding surface of the voice coil bobbin and the vibrator.
[0013]
12-05-2019
4
FIG. 1 is a view showing a first embodiment of a loudspeaker according to the present invention.
The same reference numerals as in FIG. 6 denote the same parts in FIG. In the present
embodiment, the upper circular opening of the voice coil bobbin 7 is covered with a circular flat
plate 20 made of the same material as the bobbin of the voice coil bobbin 7 and fixed to the
voice coil bobbin 7 by adhesion or the like.
[0014]
FIG. 2 is a view showing a second embodiment of the speaker according to the present invention.
The same reference numerals as in FIG. 6 denote the same parts in FIG. In the second
embodiment, the attachment of the flat plate in the first embodiment is facilitated, and the
assembling efficiency is improved. In this embodiment, a ring-shaped cylinder 21 made of paper
or the like is prepared, which is approximately equal to the inner diameter of the voice coil
bobbin 7 and can be closely fitted in the opening of the voice coil bobbin 7. 10 is bonded in
advance, and the portion of the cylinder 21 is fitted into the voice coil bobbin 7 at the time of flat
plate mounting.
[0015]
An example of the cylinder 21 is shown in FIG. In FIG. 3, the cylinder 21 has a ring shape having
an outer diameter substantially equal to the inner diameter of the opening of the voice coil
bobbin 7. After the cylinder 21 is attached to the flat plate 10, it is fitted into the opening of the
voice coil bobbin. In the illustrated example, the cylinder 21 has a perfect ring shape, but it does
not have to be a perfect ring shape, and may be, for example, a comb shape. Also, it may be fitted
on the outer surface of the voice coil instead of the inner surface. After the fitting, it is desirable
that the cylinder 21 and the voice coil bobbin 7 be adhered and fixed.
[0016]
FIG. 4 is a view showing a third embodiment of the speaker according to the present invention.
The same reference numerals as in FIG. 6 denote the same parts in FIG. In the third embodiment,
the flat plate 41 is not attached directly to the upper opening of the voice coil bobbin as in the
first and second embodiments, but the voice coil bobbin 7 and the vibration on the vibrator 5 are
vibrated. It is directly attached at a position 42 very close to the bonding site of the child 5.
Specifically, the flat plate 41 is attached at a position 0.5 to 3 mm away from the upper opening
12-05-2019
5
of the voice coil bobbin. As a result, the mechanical strength around the bonding portion 42 of
the vibrator 5 and the voice coil bobbin 7 is increased, and as a result, the effect of suppressing
the distortion of the voice coil bobbin can be obtained.
[0017]
The reason why the flat plate reinforces the voice coil bobbin and has the effect of preventing
distortion is presumed as follows. Generally, the elastic modulus in the direction parallel to the
plane of the flat plate is represented by a longitudinal elastic modulus (Young's modulus) E. Then,
for example, the spring constant in the direction parallel to the surface of the flat plate on the
voice coil bobbin having a diameter of 2 cm is E / 2. The voice coil bobbin is formed only of the
same cylindrical bobbin material from the strong voice coil winding portion to the bonding
portion with the cone vibrator at the end. If sufficient strength can not be obtained at the bonded
portion of the cone vibrator and the voice coil bobbin, it is necessary to pay attention to the
strength of the cylindrical bobbin material. It is as follows when it calculates about the case
where a flat plate is directly attached to a voice coil bobbin. The cylindrical bobbin material is
generally obtained by curling a strip of paper having a thickness of about 0.1 to 0.2 mm into a
cylindrical shape. The strain-deformation spring constant from the cylindrical shape in this case
is substantially equal to the strip-like deflection spring constant, and the deflection spring
constant K is represented by K = 4 EWH <3> / L <3>. Here, W is a strip-shaped width, L is a stripshaped length (cylindrical peripheral length), and H is a strip-shaped thickness. Assuming that
the diameter of the voice coil bobbin is 2 cm, the thickness of the bobbin material is 0.2 mm, and
the length of the portion of the cylindrical bobbin material not wound is 1 cm, in consideration of
the reinforcement of the wound portion W = 0. Substituting 5 cm, L = 6.28 cm, H = 0.02 cm into
the above equation, K = E × 5.4 × 10 <−10>. Therefore, in the case where the flat plate is
directly attached to the voice coil bobbin (the inventions of claims 1 and 2), it is reinforced with a
strength of one billion times.
[0018]
In addition, when sufficient strength can be obtained at the bonding portion between the cone
vibrator and the voice coil bobbin, attention must be paid to the strength around the bonding
portion between the cone vibrator and the voice coil bobbin. In this case, assuming that the
bonding portion peripheral width is W, if W = 0.2 cm, L = 6.28 cm, H = 0.5 cm and substituted in
the above equation, then K = E × 4.0 × 10 <−4>. Even in the case where a flat plate is attached
to the vibrator (the invention of claim 3), reinforcement is performed with a strength of 1000
times.
12-05-2019
6
[0019]
Next, the measurement result which confirms the said effect is demonstrated. FIG. 5A is a graph
obtained by adding a 0.3 V step signal to a conventional typical cone-shaped dynamic speaker
(cone diameter 6 cm input rating 6 W) and measuring the sound pressure generated on the front
surface of a cone-shaped vibrator by a microphone. The vertical axis of FIG. 5A represents the
microphone output voltage in millivolts (mV), and the horizontal axis represents time in
milliseconds (mS). In the graph of FIG. 5A, the first rising waveform a is a pulse-like waveform
generated corresponding to the step signal input. Since the pulse of the step signal input is one
pulse, in an ideal speaker, the output should immediately return to zero and disappear, but in
practice it attenuates over a period of b (about 1.5 milliseconds) after return Vibration is
continuing. This is considered to be due to the distortion of the voice coil bobbin. Note that the
low frequency transient waveform c that continues after the end of the damped oscillation is a
waveform of the low resonance frequency fo.
[0020]
FIG. 5B is a graph of the result of the same measurement performed on a speaker in which a flat
plate is attached as shown in Example 1 to the opening of the voice coil bobbin of the cone type
dynamic speaker used for the measurement of FIG. 5A. Even in the graph of FIG. 5B, after the
voltage of the first pulse a returns to zero, a slight damping oscillation exists over a period b
(about 1.5 milliseconds), but in FIG. 5B, it is compared with FIG. 5A. It can be seen that the value
is significantly improved. This is considered to be a deformation suppression effect of the voice
coil bobbin 7 by the flat plate 10. In the case where a flat plate was attached as shown in
Example 2 and Example 3, the same effect as the graph of FIG. 5B could be confirmed. Also in the
case where the speaker aperture changed, the same improvement as shown in FIG. 5B was
observed. This seems to be because the intensity ratio of the cone vibrator and the voice coil
bobbin is substantially constant even if the speaker aperture changes.
[0021]
The first embodiment of the present invention The second embodiment of the present invention
The second embodiment of the present invention The third embodiment of the present invention
Graph showing the effect of the present invention
12-05-2019
7
Explanation of sign
[0022]
DESCRIPTION OF SYMBOLS 1 ... Yoke 2, 2 ... Magnet, 3 ... Plate, 4 ... Frame, 5 ... Vibrator, 6 ...
Gasket, 7 ... Voice coil bobbin, 10 ... Voice coil , 20 ... flat plate
12-05-2019
8
Документ
Категория
Без категории
Просмотров
0
Размер файла
17 Кб
Теги
jp2008109587
1/--страниц
Пожаловаться на содержимое документа