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DESCRIPTION JPS5863298

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DESCRIPTION JPS5863298
[0001]
The present invention relates to a speaker designed to reduce distortion, particularly secondary
distortion. Generally, as shown in FIG. 1, on the base end side of the frame 2 supporting the
diaphragm 1, the center pole 3, the magnet 4 and the top plate 6 forming the magnetic gap 5
and the pole piece disposed on the center pole 3 In the speaker provided with the external
magnetic type magnetic circuit 7 consisting of 10, the voice coil 8 wound around a bobbin
provided on the base end side of the diaphragm 10 and disposed so as to face in the magnetic
gap 5 is specified. When the voice signal is driven manually, the driving force of the fundamental
wave in the speaker, that is, the driving force F1 generated in the voice coil 8 is the wire length
of the voice coil 8 located in the magnetic flux density B1 magnetic gap 5 in the magnetic gap 5
1 and the current I applied to the voice coil 8 as follows: F: BJI иии и ? Assuming that the current I
applied to the voice coil 8 is 11 cos ? t, the driving force F8 is Fl = B J! It is coswt a и и и и и 1
becomes. When a predetermined current I 1 coswt is applied to the voice coil 8 to drive the
speaker, the voice coil 8 is displaced in the axial direction over a predetermined distance X, and
the facing area between the center pole 3 and the top plate 6 Is relatively variable. Then, the
inductance L of the voice coil 8 is varied with a predetermined change amount dL according to
the displacement amount dx of the voice coil 8. Then, when a predetermined signal current
{circle over (1)} coswt is applied to the voice coil 8, an attraction force FattracL as shown by the
following equation is generated between the voice coil 8 and the center pole 3 and top plate 6
constituting the magnetic circuit 7. . ??????????? ?I, ?cos 2 yt (animal) dx 4 clx...
As apparent from the second equation, when a predetermined signal current I 1 cos ? uPt is
applied to the voice coil 8, the signal current I 1 coswt As a second-order distortion component
1-2 proportional to the square of, LF 2: 81. "cos ? 1 (-)----x is generated. By the way, the sound
pressure 5PL (db) of the speaker is given by the following equation: 5PL (db): February 0g1o (0,
199) + 94 (d?)... Where S is the diaphragm area, F , Is a driving force, and M is an effective mass
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of the vibration system. The sound pressure level of the sound pressure 5PL (F2) of the secondorder distortion with respect to the sound pressure 5PL (F,) of the fundamental wave becomes as
follows from the above-mentioned first, third and fourth expressions.
Accordingly, in order to reduce the second-order distortion component (F2), it is sufficient to
reduce the noise when the signal current 1 cosyt applied to the voice coil 8 is constant. In the
conventional speaker having the external magnet type magnetic circuit 7 as shown in FIG. 1, the
voice coil 8 and the magnetic circuit 7 'are driven by the direction in which the voice coil 8
reciprocates when the speaker is driven. +7) The facing area between the center pole 3 and the
top plate 6 is not constant. That is, when the voice coil 8 is in a stationary state where the signal
/ current I, coswi is not applied, the center of the direction crossing the magnetic gap 5 is set as
the origin O, and the signal current I, coswt is applied. The ratio of the amount of change dL of
the inductance L of the voice coil 8 to the amount of displacement dx of the voice coil 8 is
defined as-with the case of + ward displacement of the voice coil 8 in the case of + ward
deflection. As shown in. As described above, since ? changes with a constant inclination in the
reciprocation range of the poison coil 8, it takes a large value, and the second-order distortion
component F2 becomes a large value, and Deterioration of the regeneration characteristics is
inevitable. Therefore, in order to reduce the distortion of the speaker reproduction sound by
reducing the second-order distortion component 2 as described above, the present invention
reduces the distortion amount of the voice coil attached to the diaphragm by setting the
inductance L of the voice coil to the displacement amount -dx. The ratio dx of the change amount
dL is dx which is approximately zero. That is, the magnetic opposing area between the voice coil
and the center pole and top plate of the magnetic circuit is constant at any of the displacement
positions of the voice coil that reciprocates when the speaker is driven. By setting the value of ?
to be substantially zero, it is possible to achieve improvement in sound pressure reproduction
characteristics due to the influence of the second-order distortion component. Specific
embodiments of the present invention will be described with reference to the drawings. The same
members as those of the conventional example described above are denoted by the same
reference numerals and description thereof is omitted. In the case shown in FIG. 3, when a
predetermined signal current II coswt is applied to the voice coil 8 to drive the speaker, the voice
coil 8 and the magnetic circuit 7 can be used at any position within the range of change width of
the voice coil 8. The balance pole 11 formed of the same magnetic material as that of the center
pole 3 is provided on the pole piece 10 disposed on the center pole 3 so that the ratio of the area
facing each other is constant. That is, when the voice coil 8 in the inactive state is in the neutral
state, the center of the direction crossing the magnetic map 5 is the origin 0 and the voice coil 8
and the center pole 3 of the magnetic circuit 7, the pole piece 10 and the rose / The length of the
balance pole 11 is set so that the area opposed to the pole 11 is targeted.
-It should be noted that the facing areas of the voice coil 8 and the center pole 3 of the magnetic
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circuit 7 and the pole piece 1 (l and the balance pole 11 may be arranged centering on the origin
0). If the diameter of the balance pole 11 can not be increased due to the relationship of the
diaphragm 1 etc., the diameter is reduced compared to the conventional one so that the crosssectional area of the center pole 3 becomes smaller in the range where magnetic saturation does
not occur. . Further, in order to reduce the material constituting the center pole 3 and the
balance pole 11, through holes 12 are provided as shown in FIG. 4 along the direction of the
center pole 3, top plate 6 and balance pole 11 (7) 44j1. May be The inductance n of the voice coil
8 is the number n of coils wound, the permeability ? of the magnetic body such as the center
ball 3 exposed in the cylindrical voice coil 8, the magnetic body It is determined by the
relationship of n 2 ?s L = ?. Therefore, in order to reduce the inductance L of the voice coil 8,
as shown in FIG. 5, the center pole 3 is projected to the rear side of the magnetic circuit 7 so as
to increase the axial length of the center pole 3. good. Then, as shown in FIG. 5, the magnetic
circuit 7 is configured, and the facing areas of the voice coil 8 and the center pole 3, top plate 10
and balance pole 11 of the magnetic circuit 7 are targeted with the origin O at the center.
According to the speaker according to the present invention configured as described above, the
alignment at each offset position of the voice coil 8 when the predetermined signal current
IIC0Ft is applied to the voice coil 8 and driven is along with the schematic view of the air path 7.
As shown in FIG. 6 shown, there is no substantially constant inclination within the effective
displacement position of the voice coil 8, and the change amount of the inductance L of the voice
coil with respect to the displacement amount dx of the voice coil 8 The frequency characteristics
of the speaker having the conventional external magnetic type magnetic circuit, the second
distortion component port, and the third distortion component C show the characteristics as
shown in FIG. The frequency characteristic of the speaker according to the present invention as
shown in FIG. 5, the second distortion component port and the third distortion component c
show the characteristics as shown in FIG. 8, and the speaker according to the present invention
as shown in FIG. The frequency characteristics B, the second-order distortion component port,
and the third-order distortion component B show characteristics as shown in FIG. As described
above, according to the speaker configured according to the present invention, the level of the
secondary distortion component can be made sufficiently smaller than the level of the
fundamental wave, and the reproduction performance of a good reproduction sound without
distortion can be obtained.
By the way, if the sound pressure level of the second order distortion component is different
from the sound pressure level of the fundamental wave by more than 10 db, the distortion of the
reproduced sound due to the second order distortion component is sufficiently eliminated when
listening. If the area of the center 40 40 1 ball 3 and the balance pole 11 with respect to the
voice coil 8 is set so that the value becomes approximately 1 to 1 by experiments, distortion
factors to be given to the reproduced sound by secondary distortion components Magnetize.
Experiments have shown that distortion factors other than air channels can be sufficiently
reduced.
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[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view showing a conventional speaker, and FIG. 2 is a characteristic
view showing changes in voice coil displacement and inductance of the conventional speaker.
FIG. 3 is a cross-sectional view showing a speaker showing one embodiment of the present
invention, FIG. 4 is a cross-sectional view of a magnetic circuit constituting another embodiment
of the present invention, and FIG. FIG. 6 is a characteristic diagram showing the displacement of
the voice coil and the change of the inductance in the speaker according to the present invention
together with a schematic view of the magnetic circuit. 7 is a characteristic diagram showing the
frequency characteristic and the secondary distortion component of the conventional speaker,
and FIGS. 8 and 9 are characteristic diagrams showing the frequency characteristic and the
secondary distortion component in the loudspeaker according to the present invention,
respectively. 1 и и и diaphragm 311 и и и center ball T и и и magnetic circuit 8 и и и voice coil 1 [и и и
balance pole patent applicants Sony Corporation representative attorney patent attorney small
pond glance 1) village ?-1st plan ? H) ? ? Oisu coil TL TL (x) ?
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