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February 1 Showa llk Ii 'Patent Office President Yukio Miyake,-Invented material speakers 5
patent applicants' table applicant '11,', postage No. 101 \ 21., Address Chiyoda-ku, Tokyo Uchi
Kanda 2-Chome 114 No. 6 (504) Representative Director, Tokyo Electric Industry Co., Ltd.
Minoru Fukuno, (Excluding 1) ■ Japanese Patent Application No. Title of invention
Speaker 6L% Permissible coverage permanent magnet is fixed to the central part of diaphragm,
and the open magnetic circuit magnetic core which wound the voice coil opposite to the
permanent magnet is fixed and disposed on the frame. And speakers.
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel moving
magnet type speaker. A voice coil is disposed to flow an audio signal current in an equal
magnetic field of a permanent magnet fixed to a conventional speaker line, and the repulsive
action of the magnetic field generated by the current flowing in the voice coil and the magnetic
field of the permanent magnet. Most of the moving-coil speakers drive the voice coil and vibrate
the cone paper directly connected to the voice coil, but when this type of speaker is used, the
voice coil is permanent when a large audio signal current flows. It can be driven out of the
magnetic field of the magnet, so that the vibration of the cone, which is proportional to the audio
signal current, will be obtained and distortion of the loudspeaker sound will occur. Furthermore,
since the conventional voice coil is an air-core coil wound around a nonmagnetic bobble, only an
impedance of about several ohms can be obtained. Although this must be done, it is limited by
winding conditions and vibration conditions of the cone paper. Therefore, the conventional
speaker can not be directly connected to the output terminal of the amplifier, but there is a big
gap, point, and efficiency in the speaker that requires matching rounding matching. Although a
strong permanent magnet must be used, it is necessary to provide a magnetic yoke around the
permanent magnet because the magnetic flux is likely to leak to the outside, resulting in a large
size. The present invention provides a completely new "EndPage: 1P force that eliminates the
above-mentioned drawbacks. The voice coil is fixed so that the impedance of the voice coil can be
freely selected, and the permanent magnet is configured to move. The speaker will be described
in detail below with reference to the drawings. FIG. 1 is a cross-sectional view showing an
embodiment of the present invention. In the figure, 1 is, for example, a cone-shaped vibrating
paper, and a central through hole of the bottom 2 is provided. 3.51 is an annular permanent
magnet fixed to both sides of the bottom 20 of the corn paper 1, preferably! It amount is small. A
ferrite magnet having a small coercive force, for example, about 1 mm thick, is magnetized so
that the outer peripheral surface is N pole (S pole) = and the inner peripheral surface is S pole (N
pole). An open magnetic circuit core such as a wedge-shaped ferrite core is disposed so that the
open end of the magnetic core is substantially opposed to the permanent magnet 5.5 ', and a
voice coil 5. The 5 'is wound. The magnetic core Has a nonmagnetic spacer 6
interposed between its central magnetic legs to keep the interval between the permanent
magnetic 5.6's constant, and the through hole provided in the central magnetic leg is
nonmagnetic. The bolt 7 is penetrated and fixed to the second frame 10 by the nut 8.
Further, 9 is a sl frame provided so as to cover the outer periphery of the cone paper 1 and is
fixed to the second frame 10. A damper 11 is provided between the cone paper 1 and the leading
end of the frame 9 and does not adversely affect the vibration of the cone paper 1. In the abovementioned configuration, when the voice-to-noise current flows in the voice coil 5.5, the open
magnetic circuit cores 4.4 'are magnetized in opposite polarities. The right side magnetic core 4
is magnetized with the magnetic pole end on both sides to the S pole, the central magnetic leg
end to the N pole, and the left side magnetic core 4 ° on both sides by voice signal charge and a
positive half wave of current Assuming that the magnetic leg end is magnetized to N pole and the
central magnetic leg end is magnetized to 8 pole, the right permanent magnet 6 is attracted to
the magnetic core 4 and the left permanent magnet 3 'is repelled by the magnetic core 4'.
Therefore, the edge of the cone 1 is driven to the right. Next, assuming that the magnetic core
4.4 'is magnetized in the opposite polarity to that described above by the voice signal current φ
negative half wave, the bottom of the cone paper 1 is driven leftward. Therefore, if a large voice
signal current flows in the voice coil, even if the K permanent magnet is driven to repel outside
the magnetic field of one magnetic core, it is attracted by the magnetic force of the other
magnetic core, and the moving amount of the permanent magnet is compensated. As it is known,
the vibration of cone paper proportional to the audio signal current can be obtained. Thus, the
permanent magnet can repeat oscillations that are exactly proportional to the audio signal
current, and the cone paper produces a less distorted sound. FIG. 2 is a cross-sectional view of an
essential part showing another embodiment of the present invention, in which one permanent
magnet 5.5 is used for both sides of the magnetic core 4.4 in order to prevent the movement of
the permanent magnet from being restricted by the magnetic core. , And between the central
magnetic legs, and is fixed to the bottom 2 of the cone paper 1 via a very light weight spacer
12.12 such as a polystyrene film to make the distance between the magnetic core and the
magnetic core closer. FIG. 3 is a sectional view of an essential part showing still another
embodiment of the present invention, and the bottom 2 of the cone paper 1 is mostly penetrated,
and one annular magnet 15 is inserted in the through hole and fixed. It is In this way, the weight
of the vibrating permanent magnet can be halved, which has the advantage of increasing the
natural frequency of the vibrating body. In each of the above-described embodiments, the pair of
open magnetic circuit cores are disposed to face each other across the cone sheet 1, but even if
one open magnetic circuit core is omitted, it is used as a speaker. Of course, the action can be
sufficiently exhibited. Alternatively, a flat diaphragm may be used instead of the cone-shaped
vibrating paper. Since the speaker according to the present invention winds the voice coil around
the fixed open magnetic circuit core as described above and drives the permanent magnet fixed
to the cone paper, the impedance of the voice coil is free.
It can be selected high and can be adapted to 'OTL (OutputTransformer-1ess), and a combination
of a pair of magnetic core and permanent magnet can constitute a nearly closed magnetic circuit,
and it is small in size with very little leakage flux. It is characterized in that a thin speaker can be
obtained, and furthermore, a speaker sound with very little distortion can be obtained.
EndPage: 2
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an embodiment
of the speaker according to the present invention, and FIGS. 2 and 3 each show a cross-section of
the main part showing another embodiment of the present invention. 2 is the bottom of cone
paper, 3.5.13 is a permanent magnet, 4.4 is an open magnetic core, and 5.5 is a voice coil. Patent
applicant: Tokyo Electric Chemical Industry Co., Ltd. Representative: Nono Fukujibu, Masamitsu
Kawakami List of attached documents (1) Application examination request letter (1) (2)
specification statement 1 (3) drawing 1 (4) Request 1 copy (1) Representative selection layer 5.1
° M ,,,. ;r A□、□8. '1 (Re-inventor-) Patent applicant Kawaka Tama t11 Name
Masami Kawakami End Page: 3