close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JPH0614393

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 JPH0614393
[0001]
The present invention eliminates asymmetry of the electromotive force waveform based on
asymmetry of the vertical oscillation of the voice coil by eliminating the vertical asymmetry of
the magnetic flux distribution in the magnetic gap and maintaining the symmetrical magnetic
distribution. The present invention relates to a speaker magnetic circuit which eliminates the
distortion of reproduced sound. 2. Description of the Related Art A conventional speaker
magnetic circuit (21) of this type has an annular main magnet (12) mounted on a lower plate
(14) of a center pole (13) as shown in FIG. A top plate (15) is placed on the top plate, and an
annular magnetic gap (16) is formed between the top plate (15) and the center pole (13) to
assemble it. Further, as shown in FIG. 6 as another conventional example, the center pole (33) is
located above the surface of the upper plate (35), except for the portion facing the magnetic gap
(36) of the center pole (33). The upper and lower short rings (37b) which have a heat dissipating
property and are conductive, non-magnetic, and have a heat dissipating property respectively at
the extension (33a) and the narrowed portion (33b) of the base pole lower root (37a), and there
is a magnetic circuit configured to separate the portion of the center pole (33) other than the
portion facing the magnetic gap (36) from the magnetic gap (36). Since the distance between the
air gap (36) and the main magnet (32) is small, sufficient symmetry of the magnetic distribution
can not be obtained. This will be described with reference to FIGS. 1 to 6 below. Therefore, in the
conventional magnetic circuit (21) for loudspeakers of this type, symmetry can not be
maintained in the magnetic flux distribution in the vertical direction of the magnetic gap (16)
shown in FIG. Therefore, the AC magnetic flux generated from the vibrating voice coil (19)
increases the AC magnetic flux component φ2 passing through the magnet (12), as shown in
FIG. 3 (embodiment) and FIG. 5 (conventional example), Assuming that DC flux due to the main
magnet (2) and (12) magnetomotive force is φ1 and AC flux due to the magnetomotive force is
φ2 the magnetic flux density Bg of the air gaps (6) and (16) is Bg = .phi.1 + .phi.2. This φ2
12-04-2019
1
occurs around the voice coils (9) and (19), and as shown in FIG. 5, when the air gap (16) and the
main magnet (12) are close to each other, part of the φ2 is (12) passes through the same
magnetic path as the DC magnetic flux φ1. In such a state, the main magnet (12) is subjected to
modulation by the voice coil (19) magnetomotive force, that is, the input signal, and the magnetic
flux density changes to cause distortion.
As in the embodiment (FIG. 3), when the distance (D) between the air gap (6) and the main
magnet (2) is separated, the alternating current magnetic flux component passing through the
main magnet (2) in the alternating current magnetic flux φ2 decreases. Thus, the distortion is
reduced. In order to solve the problems of the conventional speaker magnetic circuit (21) of the
present invention, in the present invention, the portion other than the magnetic gap (16) of the
center pole (13) is By separating the upper and lower asymmetry of the magnetic flux
distribution in the magnetic air gap (16) and maintaining a symmetrical magnetic distribution,
based on the asymmetry of the upper and lower vibration of the voice coil (19). It is an object of
the present invention to provide a speaker magnetic circuit which eliminates the asymmetry of
an electromotive force waveform and improves the linearity of vibration to eliminate distortion of
reproduced sound. Therefore, in the conventional magnetic circuit (21) for loudspeakers of this
type, the magnetic flux distribution in the vertical direction of the magnetic gap (16) is different
because the shapes of the upper and lower magnetic circuits of the upper plate (15) are different.
, As shown in FIG. 1, because the symmetry can not be maintained and the AC magnetic flux
component generated from the vibrating voice coil (19) is not completely zero. There is a
problem that it does not become symmetrical. This is a back electromotive force generated by the
linkage between the voice coil (19) and the magnetic flux in the air gap (16), and the
electromotive force due to the vibration of the voice coil (19) is superimposed in reverse phase
with the input waveform Therefore, if the back electromotive force is distorted due to the
asymmetry of the air gap magnetic flux, as a result, the input waveform to the speaker is also
asymmetry and distorted. This distortion is included in the reproduced sound of the speaker as
current distortion, and becomes second harmonic distortion when the magnetic flux distribution
is asymmetric. Therefore, by measuring this second harmonic distortion level, the asymmetry of
the magnetic flux distribution can be known. FIG. 2 shows the second harmonic level with
respect to the fundamental wave by a dotted line (conventional example) and a solid line
(invention example). According to FIG. 2, it can be read that the second harmonic level is about 77 dB in the conventional example at around 150 Hz, but it is -83 dB in the embodiment and is
improved by about 6 dB. That is, in order to solve the problem of generating distortion by
increasing the AC magnetic flux component φ2 passing through the main magnet, which the
present invention has, in such a conventional magnetic circuit, a center pole (13) By separating
the portion other than the one facing the magnetic air gap (16) from the magnetic air gap (16),
the upper and lower asymmetry of the magnetic flux distribution in the magnetic air gap (16) is
eliminated and the linearity of the magnetic flux distribution is improved. It is an object of the
present invention to provide a speaker magnetic circuit for the purpose of
12-04-2019
2
The constitution of the present invention for achieving the above object will be described with
reference to FIGS. 3 and 4 corresponding to the embodiments. The annular main magnet (2) is
placed on the lower plate (4) of the center pole (3), the upper plate (5) is placed on it, and the
center pole (3) In the speaker magnetic circuit assembled by forming an annular magnetic gap
(6) between the center pole (3), the center pole (3) is used as the upper plate 5), which has a heat
dissipating property and is conductive and non-conductive in the narrow finished portion (3b) of
the extension (3a) and the base pole lower root (3b) Attach the upper and lower short rings (7b)
and (7a) of the magnetic body, and remove the portion other than the portion of the center pole
(3) facing the magnetic gap (6) 6) and apart from the annular main magnet (2) and the upper
plate (5), the auxiliary annular plate (8) having a large inner diameter is disposed to sandwich the
magnetic gap (6) and It is a speaker magnetic circuit (1a) spaced apart from the annular main
magnet (2) by a distance (D). [2] As shown in FIG. 4, place the annular main magnet (2) on the
lower plate (4) of the center pole (3) and place the upper plate (5 ') on it. A speaker magnetic
circuit assembled by forming an annular magnetic gap (6) with the center pole (3), leaving a
portion of the center pole (3) facing the magnetic gap (6); The pole (3) is projected and extended
upward from the surface of the upper plate (5 '), and the heat dissipation is respectively applied
to the extension (3a) and the finely finished portion (3b) of the center pole lower base (3b). The
conductive and nonmagnetic upper and lower short rings (7b) and (7a) are attached, and the
portion of the center pole (3) other than the portion facing the magnetic gap (6) is While
separating from the magnetic gap (6), the outer thickness (5c) of the upper plate (5 ') is thicker
than the thickness (5a) facing the magnetic gap (6), and the annular main magnet (2) ) And on A
portion of the magnetic gap (6) by cutting with a taper (5b) from the lower corner portion facing
the magnetic gap (6) of the upper plate (5 ') at the contact surface with the plate (5') The speaker
magnetic circuit (1b) has a gap (D) between the ring main magnet (2) and the ring main magnet
(2).
Since the present invention is configured as described above, the short rings (7a) and (7b) are
used, and the portion of the center pole (3) facing the magnetic gap (6) is narrowed. The air gap
(6) is brought into a state of magnetic saturation, and the air gap (6) and the annular ring magnet
(2) are separated to influence the signal current flowing through the voice coil and the AC
magnetomotive force thereof. By making the fluctuation of the air gap (6) magnetic flux density
as small as possible so that the driving force generated in the voice coil (9) accurately follows the
signal current, and making the center pole (3) upper and lower object structure In addition to
improving the symmetry of the vertical distribution of the magnetic flux and eliminating the nonlinear distortion, the level of distortion of the reproduced sound can be extremely lowered.
DESCRIPTION OF THE PREFERRED EMBODIMENT The construction of the present invention will
be described with reference to FIGS. 3 and 4 showing cross sections. The present invention
relates to: [1] in FIG. 3 an annular main magnet (2); Mounted on the lower plate (4), and the
12-04-2019
3
upper plate (5) mounted thereon to form an annular magnetic gap (6) with the center pole (3) to
assemble In the speaker magnetic circuit, the center pole (3) projects and extends upward from
the surface of the upper plate (5), leaving the portion facing the magnetic gap (6) of the center
pole (3), and the extension ( Upper and lower short rings (7b), (7a) with heat dissipation,
conductive, non-magnetic material in the narrow finished portion (3b) of 3a) and the center pole
lower base (3b) Mounting the center pole (3) apart from the portion facing the magnetic gap (6)
from the magnetic gap (6), and the annular main magnet (2) An auxiliary annular plate (8) having
a large inner diameter is sandwiched between the upper plate (5), and a gap (D) between the
magnetic gap (6) and the annular main magnet (2) is separated. It is a speaker magnetic circuit
(1a). [2] In FIG. 4, the annular main magnet (2) is placed on the lower plate (4) of the center pole
(3), and the upper plate (5 ') is placed thereon, In the speaker magnetic circuit assembled by
forming an annular magnetic gap (6) with the center pole (3), a portion of the center pole (3)
facing the magnetic gap (6) is left. 3) extending upward from the surface of the upper plate (5 '),
and the heat dissipation properties are provided at the extension (3a) and the finely finished
portion (3b) of the center pole lower root (3b) A conductive and non-magnetic upper and lower
short ring (7b), (7a) attached, the portion of the center pole (3) other than the portion facing the
magnetic gap (6) While separating from (6), the outer thickness (5c) of the upper plate (5 ') is
formed thicker than the thickness (5a) facing the magnetic gap (6), and the annular main magnet
(2) and Upper part Of the magnetic gap (6) by cutting with a taper (5b) from the lower corner
portion facing the magnetic gap (6) of the upper plate (5 ') at the contact surface with the gate
(5') It is a speaker magnetic circuit (1b) in which a distance (D) between a portion and the
annular main magnet (2) is separated.
Although the amount of generation of alternating current magnetic flux can be reduced to a
certain extent by the means described in the section of the problem to be solved by the invention,
the magnetic circuits of the prior art shown in FIG. 5 and the embodiments shown in FIGS. In the
structure, assuming that the direct current flux due to the magnetomotive force of the main
magnets (2) and (12) is φ1 and the alternating current flux due to the magnetomotive force of
the voice coils (9) and (19) is φ2, the magnetic gaps (6) and (16) The magnetic flux density Bg of
Bg is Bg = φ1 + φ2. This φ2 occurs around the voice coils (9) and (19), but when the air gap
(16) and the main magnet (12) are close as in the conventional example shown in FIG. The part
passes through the same magnetic path as the DC magnetic flux φ1 passing through the main
magnet (12). In such a state, since a part of the magnetomotive force of the voice coil (19) is
applied to the main magnet (12), the operating point of the main magnet (12) is always the voice
coil (19) The magnetomotive force, that is, the modulation by the input signal, changes the
magnetic flux density and causes distortion. When the air gap (6) and the main magnet (2) are
separated as shown in the embodiment, the AC magnetic flux φ2 is concentrated in the vicinity
of the air gap where the voice coil (9) exists, and the AC magnetic flux passing through the main
magnet (2) As the components are reduced, the distortion will be reduced. Considering the case
where the AC magnetomotive force is superimposed on the magnetomotive force of the main
12-04-2019
4
magnet based on the saturated state and the unsaturated state shown in FIGS. 7 and 8, the total
magnetomotive force of the magnetic circuit is H1 with H0 as the center. And H2, the operating
point changes along the B-H curve, and the air-gap flux density also changes. At this time, for
example, in the case of the unsaturated state of FIG. 8, the air-gap magnetic flux density
fluctuates between B1 ′ and B2 ′ centering on the original magnetic flux density B0 ′ of only
the main magnet corresponding to each magnetomotive force. The air gap magnetic flux density
fluctuates for each cycle of the input signal, and the driving force, that is, the reproduced sound
is distorted. Next, in the case of the saturated state of FIG. 7 as well, the magnetic flux fluctuates
between H1 and H2 centering on the magnetomotive force H0 (the original magnetic flux density
of only the main magnet) set so that the air gap magnetic flux is saturated. As apparent from FIG.
7, since the slope of the B-H curve is gentle, the change ranges of B1 and B2 corresponding to
H1 and H2 which are the change range of the magnetomotive force are the unsaturated state of
FIG. It is less than that. That is, even if the AC magnetomotive force is added to the place where it
is already saturated, the change range of the air gap magnetic flux density is further reduced.
Although the embodiments considered to be representative of the present invention have been
described above, the present invention is not necessarily limited to only the structure of these
embodiments, and includes the above-described components according to the present invention,
and the present invention In order to achieve the purpose mentioned above, the present
invention can be suitably modified and implemented within the range having the effects
mentioned below.
As is apparent from the above description, according to the present invention, the upper and
lower short rings (7b) and (7a) are used to separate the air gap (6) and the main magnet (2) from
each other. By eliminating the vertical asymmetry of the magnetic flux distribution in the air gap
(6) and using the upper plate (5) in a saturated state, the adverse effect of the AC magnetomotive
force is minimized, and the air gap magnetic flux density fluctuates due to the input signal
current. If not, the driving force becomes proportional to the input signal current. As described
above, the linearity of the driving force with respect to the input signal current is improved, and
further, along with the symmetry improvement of the magnetic flux distribution due to the
vertically symmetrical structure of the center pole (3), It came to be able to expect at the same
time the effect of becoming extremely low.
12-04-2019
5
Документ
Категория
Без категории
Просмотров
0
Размер файла
15 Кб
Теги
description, jph0614393
1/--страниц
Пожаловаться на содержимое документа