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JP2012253703

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DESCRIPTION JP2012253703
An object is to provide a speaker or a microphone capable of easily removing foreign matter such
as sand iron adsorbed by a leakage magnetic flux without deteriorating the function or
performance as a speaker or a microphone. In the case of a speaker, for example, a magnetic flux
generating member, a conductor (a conductor through which a current as an input signal flows; a
voice coil) which is vibratably disposed in a magnetic field generated by the magnetic flux
generating member, and the conductor A vibrating plate 23 that can be vibrated, and a
demagnetization / magnetization coil 24 that is disposed around the magnetic flux generation
member and that can demagnetize and magnetize the magnetic flux generation member. The
foreign matter can be easily removed by appropriately demagnetizing the magnetic flux
generating member. [Selected figure] Figure 3
Speaker or microphone
[0001]
The present invention relates to a loudspeaker or microphone directed to the amelioration of
problems due to leakage flux.
[0002]
Conventionally, as a speaker aiming at the improvement of the problem by leakage magnetic flux,
there exist some which were described in patent document 1, for example.
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That is, in Patent Document 1, as a conventional example, an inner-magnetic speaker having a
structure in which the outer periphery of a permanent magnet is surrounded by a yoke, and a
magnet in which the outer periphery of a member (permanent magnet, yoke, etc.) constituting a
magnetic circuit is covered with a shield plate. A shielded speaker is disclosed. In Patent
Document 1, as a device according to the application, a demagnetizing coil connected to a circuit
in which an alternating current is attenuated with the passage of time when the power switch is
turned on is wound around the outer periphery of the yoke of the internal magnet type speaker.
A magnetic shield speaker is disclosed which is configured to erase the residual magnetism of the
yoke by the action of a coil. The device of Patent Document 1 assumes a speaker used for a
device including a cathode ray tube such as a television, and aims to prevent distortion of an
image of the cathode ray tube due to the leakage flux from the speaker.
[0003]
Further, as a microphone directed to the improvement of the problem due to the leakage flux, for
example, there is one proposed in Patent Document 2. That is, Patent Document 2 discloses a
dynamic microphone provided with a magnetic short ring that can be manually slid to a position
where a short circuit is made between the magnetic poles of the magnet. This eliminates or
extremely reduces the leakage flux by moving the magnetic short ring to a position where it
shorts the magnetic poles of the magnet, whereby iron powder adsorbed by the leakage flux on
the vibrating plate or the like is removed. The purpose is to make it possible to take it out.
[0004]
Japanese Utility Model Application Publication No. 59-169197 Japanese Utility Model
Application Publication No. 61-602996
[0005]
However, as described in Patent Document 1 described above, the leakage magnetic flux can not
be sufficiently reduced with a mere internal magnetic speaker or magnetically shielded speaker.
Even in the invention according to the application of Patent Document 1 (a configuration in
which a degaussing coil for eliminating residual magnetism of the yoke is wound around the
outer periphery of the yoke of the internal magnet type speaker), the yoke is demagnetized The
leakage flux is zero (or almost zero) because only the induction yoke is used and the magnetism
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of the permanent magnet (member generating the magnetic flux) remains strong (it must
naturally be left to operate as a speaker). It is impossible to solve the problem caused by the
leakage flux.
[0006]
For example, in a speaker used for a portable device such as a portable telephone, when the user
drops the portable device into a sandbox, the magnetic flux is attracted to the leakage flux and
the foreign object of the magnetic material such as sand iron is And troubles such as no sound
due to rust from attached matter may occur. In addition, as another measure to solve the
problem due to the leakage flux, it is considered to use a permanent magnet with weak magnetic
force so as to reduce the leakage flux, or to use an electromagnet instead of the permanent
magnet. Be However, in the case of the former, there is a problem that the force applied to the
diaphragm of the speaker becomes weak and the sound pressure becomes small. Also, in the
latter case, the magnetic field disappears if current is not always applied, so it is necessary to
keep current flowing during use, and power consumption increases, especially for portable
devices that require power saving. Has the problem of being unsuitable.
[0007]
The speaker is a device for converting an electrical signal to physical vibration, and the
microphone is a device for converting a physical vibration to an electrical signal, but in the case
of, for example, a dynamic type using a magnet, the basic structure is the same in all cases. In
principle, the speaker can be used as a microphone or a microphone as a speaker. For this
reason, if a microphone is also used as a magnet, the problem due to the above-mentioned
leakage flux (the problem of adsorbing foreign matter of the magnetic material) similarly exists,
and the microphone of Patent Document 2 mentioned above is intended to solve this. Has been
proposed. And the technique of the said patent document 2 is applicable in principle also to the
speaker of the same principle which used the magnet. However, the technique of Patent
Document 2 adds to the problem that the microphone and the speaker are enlarged by the
amount of arranging the magnetic short ring, and it is necessary for the user to manually move
the magnetic short ring when demagnetizing. There are problems such as being annoying.
[0008]
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Therefore, an object of the present invention is to provide a speaker or a microphone capable of
easily removing foreign matter such as sand iron adsorbed by a leakage magnetic flux without
deteriorating the function or performance as a speaker or a microphone as much as possible. .
The "speaker or microphone" may be used only as a speaker, may be used only as a microphone,
or may be used as both a speaker and a microphone.
[0009]
The speaker or the microphone according to the present invention comprises: a magnetic flux
generating member for generating a magnetic flux; a conductor arranged so as to be able to
vibrate in a magnetic field generated by the magnetic flux generating member; A speaker or a
microphone comprising: a diaphragm; and a demagnetizing / magnetizing coil which is disposed
around the magnetic flux generating member and capable of demagnetizing and magnetizing the
magnetic flux generating member.
[0010]
According to the present invention, it is possible to easily remove foreign matter such as sand
iron adsorbed by the leakage magnetic flux without deteriorating the function or performance as
a speaker or a microphone as much as possible.
[0011]
It is a figure which shows the mobile telephone which is embodiment, (a) is an external
appearance perspective view, (b) is a back view.
It is a conceptual internal block diagram of the said mobile telephone.
It is a side sectional view showing a schematic structure of a speaker. (A) is a figure which shows
the hysteresis curve of each magnetic material, (b) is a sectional side view of the speaker of a
comparative example.
[0012]
First Embodiment Hereinafter, a first embodiment of the present invention (an example in which
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the present invention is applied to a handset of a mobile telephone) will be described with
reference to the drawings. FIG. 1A is an external view of a mobile phone 1 according to the
present embodiment. In this figure, the mobile phone 1 is provided with the touch panel 3 on the
main surface (the surface which is the main operation target) of the housing 2 and a display such
as a liquid crystal display or an EL panel on the back of the touch panel 3 A display unit 4 made
of a device is provided. Further, a speaker 5a as a receiver (receiver) and an in-camera 7 are
provided near the upper side of the touch panel 3, and keys 12a, 12b and 12c are provided near
the lower side of the touch panel 3. Reference numeral 2a is an opening provided at a position
corresponding to the speaker 5a of the housing 2, and a sound outlet for emitting the sound
output from the speaker 5a to the outside. The speaker 5a is at the back of the sound outlet 2a.
The configuration of the speaker 5a will be described later.
[0013]
Here, “near” means any position in a so-called frame between at least the end of the main
surface of the housing 2 and the end of the touch panel 3. The housing 2 is a frame that
accommodates built-in components such as a circuit board to configure the surface of the mobile
phone 1 and has a shape suitable for hand-holding, in this case, a thin rectangular box. Keys 12a,
12b and 12c are operation buttons pressed by the user, and for example, a menu key for
displaying a menu, a home key for displaying a desktop (initial screen), and a screen for
returning to the previous screen, respectively. It is a back key. Further, reference numeral 6 in
FIG. 1 denotes a microphone as a transmitter provided on the lower end surface of the housing 2.
Reference numeral 2 c denotes an opening provided on the lower end face of the housing 2, and
an input port for inputting an external sound to the microphone 6. The microphone 6 is at the
back of the sound input port 2c.
[0014]
In addition, although the power button, the terminal for battery charge, etc. are provided in the
arbitrary parts of the housing | casing 2, it is abbreviate | omitting in the figure. Although not
shown, a mounting portion (slot) for mounting a removable card type memory may be provided
in any part of the housing 2. Also, although it is shown in the back view of FIG. 1 (b), the out
camera 13 and a ring tone, an alarm, a musical tone, etc. are outputted to the back of the case 2
(the side opposite to the main surface). A speaker 5 b is provided. Reference numeral 2 b denotes
a sound output unit including a plurality of small holes provided at positions corresponding to
the speakers 5 b on the back surface of the housing 2. The speaker 5b is at the back of the sound
emitting unit 2b, and the sound output from the speaker 5b is emitted to the outside from the
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sound emitting unit 2b.
[0015]
FIG. 2 is a conceptual internal block diagram of the mobile phone 1. In this figure, a mobile
phone 1 includes a touch panel 3, a display unit 4, an in-camera 7, a wireless communication unit
8, an audio input / output unit 9, a central control unit 10, a power supply unit 11, an operation
unit 12, and an out camera 13. In addition, the actual circuit and apparatus which comprise the
mobile telephone 1 are mainly divided into a baseband block and a radio | wireless block
normally. When divided into blocks in this manner, the wireless communication unit 8 in FIG. 2
belongs to the wireless block, and the touch panel 3, the display unit 4, the in-camera 7, the
central control unit 10, the operation unit 12, the out-camera 13, etc. Belongs to a block.
[0016]
The wireless communication unit 8 wirelessly transmits / receives digital data to / from a nearest
base station (not shown) or the like via the antenna 8a. Digital data includes information on
incoming and outgoing calls and information on voice calls. The wireless communication unit 8
transmits and receives the digital data according to the control of the central control unit 10. For
example, the wireless communication unit 8 demodulates and outputs a wireless signal from a
network base station or a home base unit. An output signal from the wireless communication unit
8 is input to the central control unit 10 of the baseband block as an audio signal or a control
signal. Among these, the audio signal is subjected to audio processing and output as audio from
the speaker 5a or the like. The control signal is used for processing in the baseband block. A
plurality of antennas 8a are provided in the case of supporting multi-antenna technology such as
known diversity (Diversity) or MIMO (Multiple input output).
[0017]
Under control of the central control unit 10, the audio input / output unit 9 converts the audio
signal picked up by the microphone 6 into digital data and outputs the digital data to the central
control unit 10, or digital audio output from the central control unit 10 The signal is converted
into an analog signal and is loudened from the speaker 5a. Although the microphone 6 and the
speaker 5a are used for transmitting and receiving a telephone, the speaker 5a may be further
used for outputting a ringing tone and the like of the telephone (or sound accompanying movie
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reproduction and the like). As described above, the speaker 5b is provided on the back of the
housing 2 separately from the speaker 5a for receiving speech, and the ringer 5b outputs the
ringing tone etc via the audio input / output unit 9 It is also good.
[0018]
As described above, the display unit 4 has, on its front surface, the touch panel 3 that can detect
contact or approach of a part of the human body (for example, a finger of the hand). The touch
panel 3 may be, for example, a piezoelectric type or a capacitive type.
[0019]
The power supply unit 11 includes a battery formed of a primary battery or a rechargeable
secondary battery, generates various power supply voltages necessary for the operation of the
mobile phone 1 from the power of the battery, and supplies the generated power voltages to
each unit. The battery is housed in a housing recess 2d provided on the back surface of the
housing 2 and covered by a cover 14 (shown in FIG. 1 (b)).
[0020]
The operation unit 12 performs an input process of the operation of the power button or the
keys 12a, 12b, 12c, etc. described above. The touch panel 3 is for inputting dial input, character
input, command input and the like, and the central control unit 10 executes processing according
to the operation unit 12 and an input operation signal from the touch panel 3.
[0021]
The central control unit 10 is referred to as a microcomputer (hereinafter referred to as a CPU).
10a, read only semiconductor memory (hereinafter referred to as ROM). 10b, high-speed
semiconductor memory (hereinafter referred to as RAM). 10c, rewritable non-volatile
semiconductor memory (flash memory, EEPROM, etc.). Hereinafter, it is described as EPROM.
10d, and a control element of a program control system including peripheral circuits (not
shown). The central control unit 10 loads a control program stored in the ROM 10 b or the
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EPROM 10 d in advance into the RAM 10 c and executes the program by the CPU 10 a to
sequentially execute various processes to control the overall operation of the mobile phone 1.
Control.
[0022]
Next, the in-camera 7 is provided on the same surface (that is, the main surface) as the display
unit 4 in the housing 2 and can capture a still image or a moving image including the face of the
user holding the mobile phone 1, for example is there. The out-camera 13 is a camera provided
on the back surface (surface opposite to the main surface) of the housing 2 for capturing still
images or moving images of others or scenery. By operating the keys 12a, 12b, 12c and the
touch panel 3, the user can operate an application such as photographing of a still image or a
moving image by the in-camera 7 or the out-camera 13. Although not shown, a shutter button
may be provided on the side surface of the housing 2, for example, on the right side, for the user
to easily perform shutter operations and the like of shooting with these cameras.
[0023]
Then, the photographed still image and moving image data, and the audio data recorded in
synchronization with the moving image, etc., are recorded in, for example, the EPROM 10 d or a
card type memory mounted on the mounting unit described above. It is reproducible by 5a etc.
The display unit 4 can also reproduce still images and moving images (for example, those
recorded in the EPROM 10 d and the card type memory) captured by another device different
from the mobile phone 1.
[0024]
Further, the mobile telephone 1 may be provided with a TV (television) telephone function in
addition to a voice communication function of making a call by transmitting and receiving audio
data. Furthermore, the mobile phone 1 may be equipped with an electronic mail function, an
Internet connection function, a TV broadcast display function, a schedule management function,
a calculator function, an alarm (alarm) function, a music data reproduction function, etc. Needless
to say.
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[0025]
Next, the configuration of the receiver (speaker 5a) will be described with reference to FIG. The
speaker 5a is a dynamic type speaker in the sense that a diaphragm is connected to a conductor
operable in a magnetic field, but a permanent magnet material (that is, a hard magnetic material)
(generally hard magnetic flux generating member). Magnetic materials are not used, and soft
magnetic materials are used. The soft magnetic material may be, for example, iron, silicon steel,
permalloy, sendust, benmendur, soft ferrite, amorphous magnetic alloy, nanocrystal magnetic
alloy, etc. Preferably, the residual material described later with FIG. 4 (a) It is preferable that the
magnetic flux density Y1 be as large as that of the permanent magnet material, and the coercivity
X1 be much smaller than that of the permanent magnet material.
[0026]
As shown in FIG. 3, the speaker 5 a includes a magnetic flux generating member 21 made of a
soft magnetic material, a voice coil 22 (conductor) vibratably disposed in a magnetic field
generated by the magnetic flux generating member 21, and the voice coil 22. A diaphragm 23
connected to the first coil 22 and capable of vibrating with the voice coil 22; and a
demagnetization / magnetization coil 24 disposed around the magnetic flux generating member
21 and capable of demagnetizing and magnetizing the magnetic flux generating member 21; And
a frame 25. Here, the voice coil 22 is a conductor through which current flows as a signal (input
signal to the speaker). The magnetic flux generating member 21 is provided in place of the
conventional permanent magnet and fixedly attached to the frame 25. The demagnetization /
magnetization coil 24 is also disposed around the magnetic flux generation member 21 so as to
enable demagnetization and magnetization of the magnetic flux generation member 21, and is
provided in a fixed state with respect to the frame 25. The diaphragm 23 and the voice coil 22
are attached to the frame 25 by an edge (a flexible film) or a damper (not shown), and can
vibrate in the front-rear direction (vertical direction in FIG. 3) with respect to the frame 25 There
is. Here, it is preferable that the frame 25 has a shielding performance that hardly leaks the
magnetic flux to the outside.
[0027]
In addition, FIG. 3 is a figure which shows the fundamental structure of the speaker 5a, and a
detailed structure can take a well-known various aspect. For example, as in the configuration
disclosed in Patent Document 1, a yoke or a plate is provided as a member constituting a
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magnetic circuit, and the voice coil 22 is disposed in a narrow gap between the magnetic pole
formed by the yoke and the plate. It may be a mode that In the case of this embodiment, the
magnetic flux generating member 21 may be an inner magnet disposed on the inner
circumferential side of the yoke, or the magnetic flux generating member 21 may be disposed on
the outer circumferential side of the yoke.
[0028]
Here, the yoke and the plate are made of a soft magnetic material such as iron, for example, and
become a magnetic path through which a magnetic flux flows, and a member (in other words, a
magnetic flux induction member And a member different from a permanent magnet (member
generating magnetic flux) in a general dynamic speaker. In the present invention, a soft magnetic
material is used instead of a permanent magnet (hard magnetic material) as a member for
generating a magnetic flux, and the soft magnetic material is appropriately demagnetized and
used. Therefore, in order to clarify these meanings, in the present application, the term "magnetic
flux generating member" is set and used without using the term "magnet". The magnetic flux
generating member is a concept that does not include a member such as the yoke (a member
called a so-called yoke or the like).
[0029]
Further, either of the alternating current for demagnetization and the direct current for
magnetization can be selectively supplied to the demagnetization / magnetization coil 24 by a
circuit (not shown) (hereinafter referred to as a coil energizing circuit). It is a structure. The coil
energizing circuit may be a circuit provided in the above-described audio input / output unit 9 or
may be a circuit provided independently of the audio input / output unit 9. The coil energizing
circuit is appropriately operated under the control of, for example, the central control unit 10 to
flow an alternating current for demagnetization through the demagnetization / magnetization
coil 24 to demagnetize the magnetic flux generating member 21, or demagnetize / magnetize. A
direct current for magnetization is supplied to the coil 24 to magnetize the magnetic flux
generating member 21 or the like. A specific example of the control process including the timing
of demagnetization and magnetization will be described later.
[0030]
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When the demagnetization / magnetization coil 24 is provided with the members (magnetic flux
induction members) such as the yoke and the plate described above, all the magnetic circuit
constituent members (magnetic flux generation members and magnetic flux including members
such as the yokes and the like) The induction member may be demagnetized. The
demagnetization / magnetization coil of the present invention only needs to demagnetize or
magnetize at least the magnetic flux generating member. Incidentally, the invention proposed in
Patent Document 1 described above demagnetizes only a member (magnetic flux induction
member) such as a yoke and a point using a permanent magnet (hard magnetic material) as the
magnetic flux generation member, thereby demagnetizing the magnetic flux generation member
Differs from the present invention in that it is not performed.
[0031]
Next, the soft magnetic material will be described. In FIG. 4 (a), the horizontal axis represents the
strength H (Amps per meter; A / m) of the magnetic field (magnetic field), and the vertical axis
represents the magnetic flux density B (Tesla; T). Curve) is an example. In the figure, the solid line
shows an example of the soft magnetic material, and the half line shows an example of the hard
magnetic material. The magnetic material is magnetized when the magnetic material is put into
the external magnetic field to increase the strength of the external magnetic field, but even if the
external magnetic field is reduced therefrom, the magnetic force of the magnetic material (the
magnetic flux density generated by the magnetic material ) Does not decrease along the curve
during magnetization and has hysteresis. The remaining magnetic force B when the strength H of
the external magnetic field becomes zero is called the residual magnetic flux density, and the
strength H of the external magnetic field when the magnetic force B becomes zero is maintained
by applying a reverse magnetic field It is called a force.
[0032]
For example, as shown in FIG. 4A, in the soft magnetic material, the hysteresis is much smaller
and the coercivity is also much smaller than the hard magnetic material. In FIG. 4A, the point
indicated by X1 corresponds to the coercivity of the soft magnetic material, the point indicated
by Y1 corresponds to the residual magnetic flux density of the soft magnetic material, and the
point indicated by X2 is the coercivity of the hard magnetic material. The point indicated by Y2
corresponds to the residual magnetic flux density of the hard magnetic material. The magnetic
substance having a large hysteresis and a large residual magnetic flux density and coercive force
is generally called a permanent magnet, and such a general permanent magnet is made of a hard
magnetic material.
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[0033]
Next, the operation related to the speaker 5a will be described. The central control unit 10
demagnetizes a predetermined direct current for magnetizing until the magnetic force B of the
magnetic flux generating member 21 is saturated, for example, when the power supply of the
mobile phone 1 is turned on by controlling the coil energizing circuit described above. The
magnetic flux generating member 21 is magnetized by flowing through the magnetizing coil 24
for a predetermined time. Even after the magnetic flux generation member 21 is magnetized by
this magnetization operation and the energization of the direct current to the demagnetization /
magnetization coil 24 is stopped, the magnetic flux generation member 21 has a predetermined
magnetic flux density (the above-described residual magnetic flux density Y1 Is kept in the state
of generating Note that this magnetization operation may be performed each time the power of
the mobile phone 1 is turned on or the like, but if it is clear that the magnetic flux generating
member 21 is magnetized (for example, the previous magnetization operation In the case where
the demagnetizing operation is not performed after the execution, the mode may not be
performed.
[0034]
Then, when the digital signal corresponding to the sound to be output is output from the central
control unit 10 by the speaker 5a, the sound input / output unit 9 converts this digital signal into
an analog signal and inputs it to the voice coil 22 of the speaker 5a. Do. Since the voice coil 22
(conductor) is in a magnetic field formed by the magnetic flux generated by the magnetic flux
generating member 21, when an electric signal flows through the voice coil 22, the voice coil 22
generates an electric signal waveform according to Fleming's left hand rule. Move in the back
and forth direction according to (that is, vibrate). Since the diaphragm 23 is directly connected to
the voice coil 22, when the diaphragm 23 vibrates together, a sound having a waveform equal to
the analog signal is radiated into the air through the sound emission port 2a.
[0035]
According to Fleming's left-hand rule, assuming that the strength of the magnetic field (magnetic
flux density) is B and the magnitude of the current is I, the force (F ') per unit length received by
the conductor from which the current flows is F' = It can be expressed as I × B. Therefore, when
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the magnetic field B is large, F ′ becomes large and the diaphragm 23 can be shaken largely,
and high sound pressure (high volume) can be obtained for the size of the input signal. Also in
the speaker 5a of the present embodiment, by setting the residual magnetic flux density Y1 of
the magnetic flux generating member 21 as large as necessary, it is possible to secure a
predetermined sound pressure with respect to the magnitude of the input signal.
[0036]
Also in the present embodiment, the residual magnetic flux density Y1 of the magnetic flux
generating member 21 generates a leakage magnetic flux leaking to the outside from the sound
emission port 2a to some extent, whereby foreign matter of the magnetic body is attracted and
intrudes into the sound emission port 2a. There is a risk of stagnation. However, this foreign
matter can be easily removed as follows.
[0037]
That is, for example, when the power-off operation of the mobile phone 1 is performed, the
central control unit 10 controls the above-described coil energizing circuit between the power-off
operation and the actual power-off. The magnetic flux generating member 21 is demagnetized by
supplying a predetermined alternating current for demagnetizing the magnetic flux generating
member 21 for a predetermined time to the demagnetizing / magnetizing coil 24. Under the
present circumstances, since the soft magnetic material which comprises the magnetic flux
generation member 21 has small holding power as mentioned above, it can demagnetize by small
electric current. By this demagnetization operation, the residual magnetization (residual magnetic
flux density Y1) of the magnetic flux generating member 21 is removed, and the magnetic flux
density generated by the magnetic flux generating member 21 becomes zero (or almost zero). It
becomes zero.
[0038]
For this reason, the user stagnates in the sound emission port 2a by lightly waving the cellular
phone 1 with the sound emission port 2a facing downward in the demagnetized state (for
example, the power supply cut-off state) in this manner. Foreign substances such as sand iron
that has been clogged can be easily dropped and removed. As described above, the
demagnetizing operation may be performed not only on the magnetic flux generating member 21
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but also on a member such as the yoke assembled to the magnetic flux generating member 21. In
this case, the leakage flux generated by the yoke or the like can be eliminated, and the removal of
the foreign matter is further facilitated.
[0039]
As described above, with the speaker 5a of the mobile phone 1 of the present embodiment, the
function, performance, and the like of the speaker 5a are sufficiently realized by appropriately
energizing the demagnetization / magnetization coil 24 with the demagnetization current or the
magnetization-like current. It is possible to easily remove foreign matter such as sand iron
adsorbed by the leakage flux. In particular, in the case of the present embodiment, since the
magnetic flux generating member 21 is made of a soft magnetic material, the power required for
demagnetization and magnetization can be significantly reduced, and it becomes a practical
speaker for portable equipment such as a portable telephone. In addition, if the demagnetization
and magnetization by the demagnetization and magnetization coil 24 are automatically
performed by the control of the central control unit 10 as described above, the user's trouble is
completely eliminated.
[0040]
Hereinafter, the background of the present invention will be described again in comparison with
the comparative example etc. shown in FIG. 4B, and the effects of the present invention and the
first embodiment will be described in detail. FIG. 4 (b) is a schematic view of a general dynamic
type speaker used in a mobile phone. The same reference numerals are used for the same
elements as in FIG. As shown in this figure, a general dynamic type speaker uses a magnetic flux
generating member 31 made of a permanent magnet (hard magnetic material), and the
permanent magnet has a large coercive force and a high residual magnetic flux density as
described above. A considerable amount of leakage flux 32 always occurs and spreads out of the
sound outlet 2a. The leaked magnetic flux 32 can not be sufficiently eliminated by the
configuration of Patent Document 1 described above that demagnetizes only residual
magnetization of a member such as a yoke assembled to the magnetic flux generating member
31 (permanent magnet).
[0041]
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For this reason, if the mobile phone 1 is dropped outdoors (especially on a sandy beach etc.),
foreign matter (such as staples of a stapler, sand iron, etc.) outside the housing 2 is attracted to
the inside of the sound outlet 2a. As a result, the foreign matter may intrude into the sound outlet
2a and cause a malfunction. Although some foreign matter can be removed by shaking the sound
emission port 2a downward, foreign matter of the magnetic material is attracted by the leakage
flux 32, so it becomes difficult to remove it. In particular, it is very difficult to remove a magnetic
substance with fine particles, such as sand iron, if it enters inside through the sound emission
port 2a. Also, if sand iron or the like gets stuck in the sound outlet 2a, the sound quality may
deteriorate, sometimes causing rusting of the speaker (receiver) and causing no sound.
[0042]
By the way, if it is possible to temporarily cut off the leakage magnetic flux (make it substantially
zero), it is possible to remove sand iron and perform maintenance. As a measure, if an
electromagnet is used instead of a permanent magnet, the magnetic force can be made almost
zero (leakage magnetic flux is also almost zero) except during energization, but it is necessary to
keep current flowing when using a mobile phone etc. Yes, the current consumption is large and it
is not suitable for portable devices.
[0043]
Therefore, according to the present invention, first, a coil capable of demagnetizing and
magnetizing the magnetic flux generating member is disposed around the magnetic flux
generating member as in the coil 24 for demagnetizing and magnetizing of the first embodiment,
for demagnetizing current and magnetizing It is configured to be able to flow current. This makes
it possible to function as a speaker as well as to be magnetized and to have a structure capable of
demagnetizing (a structure capable of temporarily eliminating the leakage magnetic flux), making
it possible to substantially eliminate the leakage magnetic flux and facilitate the removal of
foreign matter as described above. Will be able to
[0044]
In addition, although the magnetic flux generating member may in principle be composed of a
permanent magnet material (hard magnetic material), in the present invention, the magnetic flux
generating member is further composed of a soft magnetic material having a large residual
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magnetization but a small coercive force. did. That is, although it is possible to demagnetize even
a permanent magnet in principle, in that case a large amount of current consumption is required,
and this is not a material suitable for portable devices such as mobile phones. By using a soft
ferromagnetic material (soft magnetic material) instead of a permanent magnet material,
demagnetization and magnetization can be performed with a small consumption current, and
maintenance for removing sand iron etc. is not accompanied by performance deterioration such
as consumption current increase. As a result, the performance as a speaker (for example, the
performance of the above-described sound pressure) can be secured sufficiently high.
[0045]
That is, the feature of the soft magnetic material is that the magnetic flux density is large and the
coercivity is small. Compared with a permanent magnet, it is susceptible to external influences
because of its small coercivity, and it is possible to have a large magnetic flux density with a
small external magnetic field. By utilizing this characteristic, normally, when used as a speaker, it
is magnetized to a soft magnetic material as a magnetic flux generating member and used as a
permanent magnet. When removing the foreign matter of the magnetic substance clogged in the
sound emission port, an alternating current is supplied to the demagnetization / magnetization
coil to demagnetize the soft magnetic substance. Then, the leakage magnetic flux disappears and
the force for attracting the foreign matter of the magnetic body is lost, so that the foreign matter
attracted by the leakage magnetic flux can be easily removed by shaking the sound emission port
downward.
[0046]
Moreover, unlike the case of using a magnet having a weak magnetic force that reduces the
leakage magnetic flux, a sufficiently high magnetic force can be obtained with a soft magnetic
material in a magnetized state, so the same degree as in the case of using a permanent magnet In
addition, the force applied to the diaphragm with respect to the input signal of the same
magnitude becomes stronger and the sound pressure becomes larger. In addition, power
consumption does not increase as in the case of using a permanent magnet for demagnetization
or using an electromagnet instead of the permanent magnet.
[0047]
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16
Another Embodiment Next, another embodiment of the present invention will be described. First,
in the first embodiment described above, the present invention is applied to the speaker 5a as a
receiver (receiver), but the present invention is applied to another speaker (for example, the
above-mentioned speaker 5b) and a microphone (for example, the above-mentioned microphone
6). May apply. In the case of a microphone, a conductor connected to a diaphragm and placed in
a magnetic field (a conductor through which a current as an output signal of the microphone
flows) is called a moving coil in a moving coil type microphone, and a movable metal ribbon in a
ribbon type microphone It is called etc.
[0048]
Moreover, there are various modes as control contents of the demagnetizing operation and the
magnetizing operation by the coil for demagnetizing and magnetizing. For example, the central
control unit 10 may perform the demagnetization operation or the magnetization operation
according to an input operation on the touch panel 3 or the operation unit 12 of the mobile
phone 1 by the user. For example, when the user performs an operation of selecting a
maintenance mode for removing sand iron or the like from the sound emission port 2a, the
central control unit 10 performs the demagnetizing operation, and when the user performs an
operation of canceling the maintenance mode, The program of the central control unit 10 may be
set so that the control unit 10 performs the above-described magnetization operation. Even in
this case, since the mechanical operation by the user for demagnetizing as described in Patent
Document 2 described above is unnecessary, the user's work is easy.
[0049]
In the embodiments described above, a mobile phone has been described as an example, but the
present invention is not limited to a mobile phone, for example, a PDA (portable information
terminal), a personal computer (for example, a notebook PC, a tablet PC), music The present
invention is applicable to a speaker or a microphone provided in various devices such as a player,
a game machine, a portable radio, an IC recorder, and the like. In particular, although it is
suitable for a portable device, a speaker or a microphone provided other than the portable device
may be used.
[0050]
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17
The features of the present invention will be additionally described below. Although a part or all
of the above-mentioned each embodiment may be described as the following supplementary
notes, it is not limited to the following. (Supplementary Note 1) A magnetic flux generating
member for generating a magnetic flux, a conductor arranged so as to be able to vibrate in a
magnetic field generated by the magnetic flux generating member, and a diaphragm which is
connected to the conductor and can be vibrated together with the conductor. A speaker or a
microphone comprising: a demagnetizing / magnetizing coil which is disposed around the
magnetic flux generating member and capable of demagnetizing and magnetizing the magnetic
flux generating member.
[0051]
(Supplementary Note 2) The speaker or the microphone according to claim 1, wherein the
magnetic flux generating member is made of a soft magnetic material.
[0052]
DESCRIPTION OF SYMBOLS 1 mobile phone 2 case 2a sound emission opening 5a speaker 6
microphone 9 voice input / output unit 10 central control unit 21 magnetic flux generating
member 22 voice coil (conductor) 23 diaphragm 24 demagnetization / magnetization coil
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18
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