JP2008228214

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DESCRIPTION JP2008228214
The present invention provides a speaker device which can be miniaturized while improving
sound quality. SOLUTION: The LED 150 and the phototransistor 160 are attached in a state of
being held by a holding member 210 outside the cone paper 110, and the light path in the hole
of the holding member 210 is interlocked with the vibration of the cone paper 140 shields and
releases. Thereby, the light reception amount detected by the phototransistor 160 changes. In
order to improve the sound quality, a signal indicating the detected light receiving amount is
used as a feedback signal in the MFB system. Further, the size of the holding member 210 can be
variably adjusted by the first and second holding members 211 and 212 according to the
diameter and depth of the cone. [Selected figure] Figure 7
Speaker device
[0001]
The present invention relates to a speaker device, and more particularly to a speaker device
having a sound quality improvement function.
[0002]
Conventionally, in order to improve the sound quality of a bass speaker, there is known a method
of detecting a movement of cone paper and controlling a signal.
As a method of realizing this method, MFB (Motional Feed Back) that provides feedback to a
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speaker has been proposed.
[0003]
In order to realize the MFB, a detection coil is provided on the speaker. The output from the
detection coil is fed back to the control circuit as a feedback signal. The control circuit uses the
output to correct the target value and provides a corrected signal to the speaker. As a result, the
movement of the corn paper is controlled, and the bass can be reproduced faithfully.
[0004]
Here, with reference to FIG. 12, a speaker system 90 to which the conventional MFB is applied
will be described. FIG. 12 is a diagram schematically showing the configuration of speaker
system 90. Referring to FIG. The speaker system 90 includes a control circuit 190 incorporating
an amplification circuit for MFB and an MFB speaker 900. The MFB speaker 900 includes cone
paper 910, a voice coil 930, a detection coil 950, and a detection coil magnet 940. The output
from the amplification circuit of control circuit 190 is input to voice coil 930. The output from
the detection coil 950 is input to the control circuit 190.
[0005]
However, the speaker system of FIG. 12 has the following problems. First, since the detection coil
950 and the detection coil magnet 940 are required, the speaker system 90 may be large.
Moreover, it becomes difficult to miniaturize the speaker system 90.
[0006]
Second, when the speaker system 90 is miniaturized, the voice coil 930 and the detection coil
950 will be close to each other. The magnetic flux generated due to the current flowing through
the voice coil 930 generates an electromotive force in the detection coil 950. As a result, the
output value from the detection coil 950 may fluctuate, and the accuracy in the MFB may
decrease.
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[0007]
In order to solve such a subject, for example, in patent document 1, it replaces with a detection
coil and is provided with the sensor which detects a vibration of a speaker. A function is provided
to reduce distortion generated from the speaker based on the detection output of the sensor
regardless of the passage of time and even when a sufficient feedback gain can not be obtained.
[0008]
Moreover, in patent document 2, the irradiation position of the reflected light inside the cap of a
speaker is detected, the output signal from a signal source is amplified based on a detection
result, and the amplified signal is supplied to a speaker part. This provides a speaker system
having high linearity.
[0009]
Further, in Patent Document 3, the vibration displacement detection signal of the speaker is
configured to be fed back to the speaker drive circuit to detect the vibration displacement with
high accuracy. JP, 2006-197206, A JP, 2003-087892, A JP, 06-284492, A
[0010]
In patent document 1, although the optical pick-up of a laser beam is used as a sensor, since a
laser is expensive and is comparatively large, the miniaturization of a speaker system is inhibited.
[0011]
In patent document 2, since the reflected light in the inside of a cap is detected, depending on the
state of the inner surface of a cap, diffuse reflected light may arise and an exact detection may
not be able to be performed.
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In addition, since it is necessary to provide a light emitting element and a light receiving circuit
inside the speaker, depending on the type of the speaker, a special installation space may need to
be provided, which may hinder miniaturization.
[0012]
Further, in Patent Document 3, the mechanism for detecting the vibration displacement of the
speaker is provided at the voice coil peripheral portion inside the speaker, so it is necessary to
provide an installation space specially depending on the type of the speaker, and the
miniaturization is inhibited. May be
[0013]
The present invention has been made to solve the above-described problems, and an object
thereof is to provide a speaker device that can be miniaturized while improving the sound
quality.
[0014]
Another object of the present invention is to provide a speaker device capable of preventing a
decrease in accuracy of feedback control.
[0015]
A speaker device according to one aspect of the present invention receives a given audio signal,
and vibrates a vibration unit based on the input voice signal, thereby detecting a vibration by the
speaker unit that outputs sound to the outside of the speaker device A vibration detection unit, a
control unit for controlling an audio signal given to the speaker unit based on the vibration
detected by the vibration detection unit, and a holding member, the vibration detection unit
being a side on which the sound of the speaker unit is output Light-emitting means disposed at
the position, light-receiving means disposed at a position to receive the light emitted from the
light-emitting means and outputting a signal according to the amount of light received, A light
blocking means for blocking light, the holding member is externally attached to the speaker
portion, and holds the light emitting means and the light receiving means, and the control
portion receives the audio signal as the light receiving means And the holding member is variably
adjusted in size for attachment to the speaker unit, and the holding member includes a size
adjusting member for adjusting the size, and is held. The member is adjusted to a size according
to the shape of the vibrating portion by the size adjusting member, the vibrating portion has a
cone shape, and the holding member has an optical path forming means for forming an optical
path from the light emitting means to the light receiving means The holding member is coupled
to the frame of the speaker unit, the light emitting means includes a light emitting diode, the light
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receiving means includes a photodiode, and the speaker unit includes a coil for receiving an input
of an audio signal output from the control unit; And a diaphragm driven by the generated driving
force.
[0016]
A speaker device according to another aspect of the present invention receives a given audio
signal, and vibrates a vibrating portion based on the input signal, thereby outputting a voice to
the outside of the speaker device, and a speaker portion A vibration detection unit that detects
vibration, a control unit that controls an audio signal provided to the speaker unit based on the
vibration detected by the vibration detection unit, and a holding member, the vibration detection
unit outputs the sound of the speaker unit Connected to the light emitting means, the light
receiving means disposed at the position to receive the irradiation light from the light emitting
means, and outputting a signal according to the amount of light received, and connected to the
vibration unit, the light emitting means to the light receiving means A light blocking means for
blocking an optical path to the light source, the holding member is externally attached to the
speaker portion, and holds the light emitting means and the light receiving means, and the
control portion receives the audio signal Given to the speaker portion after controlled based on a
signal al outputted, the retaining member, the size for mounting the speaker unit is adjusted
variably.
[0017]
Preferably, the holding member includes a size adjusting member for adjusting the size.
Preferably, the holding member is adjusted by the size adjusting member to a size according to
the shape of the vibrating portion.
[0018]
Preferably, the vibrating part has a cone shape.
Preferably, the holding member has an optical path forming means for forming an optical path
from the light emitting means to the light receiving means.
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[0019]
Preferably, the holding member is coupled to the frame of the speaker unit.
Preferably, the light emitting means comprises a light emitting diode.
[0020]
Preferably, the light receiving means comprises a photodiode.
Preferably, the speaker unit includes a coil that receives an input of an audio signal output from
the control unit, and a diaphragm driven by a driving force generated by the coil.
[0021]
According to the present invention, the detection coil is not required to detect the movement of
the vibrating unit.
As a result, it is possible to accurately detect the movement of the vibrating unit, and feedback
control can be accurately realized to improve the sound quality. Further, the vibration detection
unit for detecting the movement of the vibration unit instead of the detection coil is provided
outside the speaker device. As a result, since it is not necessary to provide a mechanism for
detecting the movement of the vibration unit inside the speaker unit, the miniaturization of the
speaker unit is not hindered.
[0022]
In addition, the holding member for holding the light emitting means and the light receiving
means of the vibration detection unit can be mounted without being influenced by the shape of
the speaker unit because the size for mounting on the speaker unit is variably adjusted.
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[0023]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
In the following description, the same components are denoted by the same reference numerals.
Their names and functions are also the same. Therefore, detailed description about them will not
be repeated.
[0024]
A speaker system 10 according to an embodiment of the present invention will be described with
reference to FIG. FIG. 1 is a diagram schematically showing the configuration of a speaker system
10. The speaker system 10 includes an MFB (Motional Feed Back) speaker 100 and a control
circuit 19. The MFB speaker 100 includes a cone paper 110, a coil portion 120, a magnetic
circuit 130, a light shielding plate 140, a light emitting diode (LED) 150, and a phototransistor
160. The phototransistor 160 is disposed at a position capable of receiving the light output from
the LED 150 and opposite to the LED 150. The light path connecting the LED 150 and the
phototransistor 160 is covered by a tube or other closed member (not shown). This prevents
external light from entering the light path.
[0025]
Next, peripheral circuits of the speaker system 10 will be described with reference to FIG. In FIG.
2, a speaker system 10 is provided in a CD reproducing apparatus for outputting an audio signal
reproduced from a medium 11 of, for example, a CD (Compact Disc) or a DVD (Digital Versatile
Disc).
[0026]
The CD reproduction apparatus receives the digital audio signal reproduced from the medium 11
and decodes and outputs the signal processing unit 13 and the audio signal output from the
signal processing unit 13 and performs processing on sound quality. A sound quality processing
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unit 15 for outputting, a D / A (Digital / Analog) conversion circuit 17 for converting a digital
audio signal output from the sound quality processing unit 15 into an analog signal and
outputting the analog signal, and a speaker system 10 are provided. The audio signal output
from the D / A conversion circuit 17 is applied to the amplifier 191 of the control circuit 19. The
amplifier 191 inputs an audio signal to be supplied, amplifies the audio signal according to a
predetermined gain, and supplies the amplified audio signal to the coil section 120 of the
magnetic circuit 130 of the MFB speaker 100. As a result, an audio signal (current) flows through
the coil unit 120, and a force corresponding to the current flowing through the magnet
(magnetic circuit 130) in the coil unit 120 is applied. Since the magnet is fixed, the coil section
120 vibrates, and the cone paper 119 integrated with the coil section 120 shakes in conjunction
with the vibration. The vibration of the cone paper 119 shakes the air in the same manner to
produce a sound (sound).
[0027]
Here, when the MFB speaker 100 operates to output a sound according to a given audio signal,
the signal detected by the photodiode 160 is given to the feedback control unit 192 of the
control circuit 190. The feedback control unit 192 adjusts the amount of gain given to the
amplifier 191 in accordance with the supplied signal, and gives the adjusted amount of gain to
the amplifier 191.
[0028]
The light shielding plate 140 is disposed on the light path. The light shielding plate 140 is in the
form of a lightweight thin film, for example, made of a resin material, but other materials may be
used. In addition, the light shielding plate 140 does not have to be the same material. That is, it
may be made of a material having a light shielding property only at a portion where the light
emitted from the LED 150 may pass.
[0029]
The phototransistor 160 receives incident light from the LED 150 to detect the amount of light
received. A voltage signal of a level corresponding to the detected light receiving amount is
output. An output signal from the phototransistor 160 is provided to a feedback control unit 192.
The feedback control unit 192 has a function of feeding back the difference between the target
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value and the output value indicated by the signal supplied from the phototransistor 160 to a
new target value.
[0030]
More specifically, the feedback control unit 192 detects the movement of the cone paper 110
according to the amount of light received by the phototransistor 160 which changes according to
the position of the light shielding plate 140. The feedback control unit 192 calculates the
difference between the detected value and the target value given to the coil unit 120. The
feedback control unit 192 newly calculates the level of the signal given to the coil unit 120 in
consideration of the difference, and gives a signal of the calculated level to the amplifier 191 as a
gain signal. The amplifier 191 amplifies the audio signal input from the D / A conversion unit 17
in accordance with the level of the gain signal supplied, and sends the amplified audio signal to
the coil unit 120. Thereby, the movement of the cone paper 110 as the diaphragm is corrected.
For example, when the movement of the cone paper 110 is smaller than the target value in the
low-pitch range (when the amplitude of the cone paper 110 is smaller than the target amplitude),
the voice signal considering the difference between the target value and the detection value is
the coil unit 120 Is input to In this case, an audio signal having an amplitude reflecting a
difference (attenuation rate with respect to the target value) rather than a signal according to the
target value is applied to the coil section 120.
[0031]
An optical path, which is a closed space, is formed between the LED 150 of the holding member
210 and the phototransistor 160 in order to prevent external light from entering. One end of the
light shielding plate 140 is integrally connected to a vibrating portion (for example, a center cap
240 described later) of the speaker unit constituting the MFB speaker 100, and the other end
opposite to one end is located on the light path 310 side. The cone paper 110 forms a vibrating
portion. When the vibrating portion made of the center cap 240 and the cone paper 110 vibrates
by the driving force generated based on the current input to the coil portion 120, the light
shielding plate 140 vibrates according to the vibration. One end of the light shielding plate 140
vibrates in a direction substantially orthogonal to the light path. When all the light output from
the LED 150 due to the vibration is blocked by the light blocking plate 140 (when the light path
is almost completely blocked), the phototransistor 160 does not receive the light. In this case, the
output value from the phototransistor 160 is a signal value representing almost zero light
reception.
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[0032]
On the other hand, when the light path is not blocked by the light shielding plate 140, all the
irradiation light from the LED 150 is received by the phototransistor 160. Further, when a part of
the light path is blocked by the light blocking plate 140, the light passing through the light path
of the unblocked part is received by the phototransistor 160. In this case, a voltage signal having
a value corresponding to the amount of received light is output from the phototransistor 160.
[0033]
In the present embodiment, although the LED 150 is used as the light emitting means, the light
emitting means is not limited to the LED 150. Similarly, although the phototransistor 160 is used
as the light receiving means, the light receiving means is not limited to the phototransistor 160.
The light emitting means and the light receiving means may be provided to the housing (not
shown) of the speaker system 10.
[0034]
In addition, the speaker system 10 according to the present embodiment includes a control
circuit 19 as hardware for realizing feedback of the MFB speaker 100. However, the feedback
process can also be realized as cooperation between hardware and software by the processor
executing software stored in the memory.
[0035]
With reference to FIG. 3, the attachment aspect with respect to the speaker part of the light
detection mechanism which concerns on this Embodiment is demonstrated. FIG. 3 is a view
showing a mounting structure of the LED 150 and the phototransistor 160 in the speaker
portion of the MFB speaker 100. As shown in FIG.
[0036]
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The LED 150 and the phototransistor 160 are mounted so as to be held by the integrally formed
holding member 210. The holding member 210 is molded of, for example, a resin. The holding
member 210 has a hole 220 for the light shielding plate 140 to slide by vibration between the
positions where the LED 150 and the phototransistor 160 are arranged. The holding member
210 is externally attached to the speaker device. Specifically, both ends of the holding member
are connected to the non-oscillating portion (for example, the flange portion 230 or the baffle
surface) of the speaker portion. The cavity 220 is positioned to be directly above the center cap
240.
[0037]
Next, the configuration of the holding member 210 will be further described with reference to
FIG. FIG. 4 is a view showing the holding member 210 from the horizontal direction. The holding
member 210 includes an optical path 310 between the portion where the LED 150 and the
phototransistor 160 are disposed. The light path 310 is closed to prevent light from the outside.
The optical path 310 is formed by, for example, injection molding the holding member 210. The
hole 220 is formed in the middle of the light path 310. The light shielding plate 140 moves the
hole 220 in the direction (vertical direction in the drawing) pointed by the arrow AR so as to
block the light path 310 in conjunction with the vibration of the center cap 240. This movement
is changed by the vibration of the vibration portion (the center cap 240 and the cone paper 110
integrally formed therewith) of the speaker portion. This change corresponds to the vibration
pattern of the sound.
[0038]
FIG. 5 is a view showing the holding member 210 from above. In the hole portion 220, a
sufficient gap is provided between the light shielding plate 140 and the side surface of the hole
portion 220 so that the light shielding plate 140 slides without being in contact with the side
surface. In the middle of the side surface, an optical path 310 through which light for the
phototransistor 160 is transmitted is formed.
[0039]
The positional relationship between the holding member 210 and the speaker unit 10 will be
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further described with reference to FIG. FIG. 7 is a diagram illustrating the speaker unit 10 from
the horizontal direction. The holding member 210 is adhered to the flange portion 230 of the
speaker unit 10 via the adhesive layer 300. The light shielding plate 140 is attached to the center
cap 240. The mounting method is not particularly limited. For example, as shown in FIG. 6, it
may be attached by an adhesive layer 300. Alternatively, in another aspect, it may be integrally
molded with the center cap 240.
[0040]
Thus, the size of the light shielding plate 140 and the holding member 210 is designed according
to the size of the speaker and attached to the speaker main body as shown in FIG. , You can
reduce the cost.
[0041]
The attachment of the holding member 210 to the speaker will be further described.
Referring to FIG. 3, the holding member 210 has a columnar shape, and the longitudinal
direction thereof is attached so as to correspond to the direction in which the diameter of the
cone paper 110 extends. The width in the lateral direction may have a size that can
accommodate at least the LED 150 and the phototransistor 160 and can form the cavity 220.
Here, since the holding member 210 is attached in the radiation direction of the sound wave
from the MFB speaker 100, the width of the holding member 210 is designed so as not to block
the sound wave.
[0042]
The holding member 210 is hollow inside the both end portions in the longitudinal direction, and
a part of the first holding member 211 slides in a direction in which the diameter of the cone of
the cone paper 110 pointed by the arrow DR2 extends. It can be freely inserted and removed.
The portion of the first holding member 211 inserted into and removed from the hollow of the
holding member 210 has substantially the same shape as the shape in the hollow. When the first
retaining member 211 is inserted into the cavity of the retaining member 210, the retaining
members 210 and 211 align the screw holes previously formed in both members and screw 213
into the aligned screw holes. And tighten both parts together. Here, in a portion of the first
holding member 211 inserted into the holding member 210, a plurality of screw holes are
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formed in a line at intervals. After inserting a part of the first holding member 211 into the cavity
of the holding member 210 so as to align one of the screw holes with the screw hole formed in
the holding member 210, the aligned screw hole Insert the screw 213 into the two and tighten
both members together. Therefore, the size of the holding member 210 in the longitudinal
direction can be made extensible and contractible by the position of the screw hole to be aligned
among the row of screw holes formed in the first holding member 211. The first holding member
211 is also formed of the same material as the holding member 210.
[0043]
The first holding member 211 is a column formed in an L shape bent at a right angle, and the
inside is a cavity. The long end of the L is attached to the holding member 210. A part of the
second holding member 212 is freely inserted and removed in the cavity at the short end of the
L-shape by sliding in the depth direction of the cone of the cone paper 110 pointed by the arrow
DR1. The part of the second holding member 212 inserted into and removed from the hollow of
the holding member 211 has substantially the same shape as the shape in the hollow.
[0044]
When the second retaining member 212 is inserted into the cavity of the first retaining member
211, the retaining members 211 and 212 align the screw holes pre-formed in both members and
align the screw 214 Fit both screw members together. Here, in the portion of the second holding
member 212 inserted into the first holding member 211, a plurality of screw holes are formed in
a row at intervals, and one of the screw holes and After inserting a portion of the second holding
member 212 into the cavity of the first holding member 211 so as to align with the screw holes
formed in the first holding member 211, screws 214 are screwed into the aligned screw holes.
And tighten both parts together. Therefore, depending on the position of the screw holes aligned
in the row of screw holes formed in the second holding member 212, the length of the leg for
attaching the holding member 210 to the flange portion 230 according to the depth direction of
the cone Can be adjusted freely. The second holding member 212 is also formed of the same
material as the holding member 210.
[0045]
The second holding member 212 is an L-shaped column bent at a right angle, and the inside is a
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cavity. One end of the L-shape is attached to the first holding member 211. The other end of the
L is connected to the flange 230. The other end portion and the flange portion 230 align the
screw hole 215 formed in the other end portion with the screw hole 231 formed in the flange
portion 230, and screw the screw 216 into the aligned screw hole. Are connected by clamping
both members together.
[0046]
As shown in FIG. 7, the holding member 210 and the first and second holding members 211 and
212 are integrally connected by screws 213 and 214, and the connected holding member is a
flange of the speaker via the screw 216. It is integrally connected to the part 230. Here, since the
axis extending in the direction of the arrow DR1 and the axis extending in the direction of the
arrow DR2 are orthogonal to each other, the longitudinal size of the holding member 210 and
the length of the attachment leg to the flange 230 It is possible to attach the holding member
210 to the speaker unit in a state where it is freely matched to the stem size (diameter and depth
size of the cone formed by the cone paper 110).
[0047]
Here, the other end of the second holding member 212 is attached to the flange portion 230, but
it may be attached so as to sandwich the housing of the speaker device shown in FIG. 12
described later.
[0048]
By doing this, the holding member 210 can be attached regardless of the size of the speaker unit
or the housing size of the speaker device.
In addition, since the size of the holding member 210 can be freely adjusted, the holding member
210 can be shared by speakers of different sizes.
[0049]
Furthermore, although the holding members are connected by screwing in this case, it may be a
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method that does not use screwing. For example, in the first holding member 211, a bellows-like
convex-concave shape is formed on the inner side surface on which the second holding member
212 slides for insertion, and the first holding member 211 of the second holding member 212 is
formed. Similarly, bellows-like irregularities are formed on the surface sliding with the inner
surface of the cylinder, and the bellows-like surfaces slide while being rubbed against each other,
and the two are joined in a state where the irregularities engage with each other. You may do so.
The same can be applied to the connection between the first holding member 211 and the
holding member 210.
[0050]
In the state where the holding member 210 is attached in such a manner, it is assumed that the
speaker operates. In this case, when the cone paper 110 vibrates according to the magnetic force
generated by the magnetic circuit 130, the center cap 240 also vibrates, and the light shielding
plate 140 bonded to the center cap 240 also vibrates according to the arrow AR. During this
time, the LED 150 receives power and continues to output light having a predetermined
intensity. When the light blocking plate 140 blocks or opens the light path 310 to the
phototransistor 160, the amount of light received by the phototransistor 160 changes in
response to such an operation. A voltage signal of a level corresponding to each light amount is
provided to the feedback control unit 192 of the control circuit 19 as an output from the
phototransistor 160. The feedback control unit 192 calculates the difference between the signal
value given to output the sound to the speaker unit 10 and the output value from the
phototransistor 160 based on the input signal. The feedback control unit 192 executes feedback
control according to the difference to calculate the target value again. The amplifier 191 outputs
an audio signal according to the target value and sends it to the coil unit 120.
[0051]
Next, the positional relationship between the light shielding plate 140 and the holding member
210 will be described with reference to FIG. FIG. 8 is a diagram showing the positional
relationship between the light path 310 formed in the holding member 210 and the light
shielding plate 140. As shown in FIG. The light path 310 has a width 610 determined in
accordance with the amount of movement of the light blocking plate 140 with respect to the
movement direction. The width 610 is, for example, a length equal to or greater than the
maximum amplitude of the speaker unit 10 of the MFB speaker 100. Furthermore, the front end
portion of the light shielding plate 140 is positioned to be positioned at the center of the width
610 when the speaker unit (more specifically, the center cap 240 or the cone paper 110) is not
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vibrating. In this way, it is possible to linearly detect changes in the amount of light for the
positive direction swing and the negative direction swing of the light shielding plate 140. The
positive direction refers to the direction from the center cap 240 toward the other end of the
light shielding plate 140. The negative direction is the opposite direction.
[0052]
The relationship between the amplitude and the light receiving amount in the speaker system 10
according to the present embodiment will be described with reference to FIG. FIG. 9 is a diagram
showing the relationship between the amplitude of the speaker section of the MFB speaker 100
and the amount of light received by the phototransistor 160.
[0053]
When the value of the amplitude is zero, the other end of the light blocking plate 140 is located
at the center of the width 610 forming the light path 310 as described above. Therefore, half of
the light emitted from the LED 150 is received by the phototransistor 160. Therefore, when the
maximum value of the light amount output from the LED 150 is Lmax, the value of the light
reception amount by the phototransistor 160 is half of the maximum value (0.5 Lmax) when the
amplitude is zero. Then, as the amplitude increases in the positive direction, the light blocking
plate 140 blocks the light path 310, and the amount of light received decreases.
[0054]
On the other hand, when the light shield plate 140 moves in the negative direction from the
position where the amplitude is 0 (when the cone paper 110 moves in the negative direction), the
light path 310 becomes larger. Thereby, the amount of light received by the phototransistor 160
is increased.
[0055]
Next, the characteristics of the speaker system 10 according to the present embodiment will be
described with reference to FIG. FIG. 10 shows a change in signal value output from control
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circuit 19. Referring to FIG. Note that the curves shown in FIG. 10 are used as a simplified
illustration in order to make the features of the present invention accurate.
[0056]
As shown in FIG. 10A, the control circuit 19 outputs a signal value as represented by the curve
810 as an initial command to the MFB speaker 100. When the MFB speaker 100 operates in
response to the signal value, the position of the vibrating portion is identified by the amount of
light received by the phototransistor 160. In this case, the position of the light blocking plate
140 is represented as a curve 820 whose level is lower than that of the signal 810 which is the
initial signal value. That is, the light shielding plate 140 does not follow the input signal.
[0057]
Therefore, the control circuit 19 calculates the difference between the value corresponding to the
curve 810 and the value corresponding to the curve 820 (that is, the difference between the
initially given command value and the position actually detected) A signal value for feedback
control to 100 is determined. Specifically, the control circuit 19 uses the feedback control unit
192 to calculate a signal value (gain signal) in consideration of the difference which does not
follow the actually given command, in consideration of the difference (FIG. Curve 830) in 10 (B).
In one aspect, for example, the inverse of the ratio of the detected value to the target value is
used as the compensation value. Other compensation values may be used. In this case, the
calculation of the compensation value may be determined in consideration of the characteristics
of the elements constituting the MFB speaker 100 (for example, the sound output characteristics,
the cone paper 110, the material of the center cap 240, and the like).
[0058]
Since the signal value calculated in this manner is applied to the amplifier 191, the audio signal
supplied from the D / A conversion circuit 17 is amplified according to the calculated signal
value, and the audio signal after amplification is transmitted from the control circuit 19 to the
MFB. The speaker 100 is provided. Thereby, the light shielding plate 140 vibrates at a value
reflected by a predetermined attenuation amount (curve 840). This predetermined amount of
attenuation is, in other words, the difference between the target value specified by FIG. 10A (the
difference between curve 810 and curve 820). As a result, according to the speaker system 10
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according to the present embodiment, since the delay in following the given signal value is
compensated, it is possible to output more faithful sound (in particular, the bass range).
[0059]
FIG. 11 is a view showing an overview of the speaker device according to the present
embodiment. Since the holding device 210 to which the LED 150 and the phototransistor 160
are attached is attached to the speaker device from the outside, there is no need to secure a
space inside the speaker device for attaching the vibration detection mechanism of the vibration
part. This does not hinder the miniaturization of the speaker device.
[0060]
As described above, according to the speaker system 10 according to the present embodiment,
the movement of the cone paper 110 is performed by detecting the movement of the light
shielding plate 140 which can ignore the weight. Therefore, since there is almost no influence on
the detection signal by the light shielding plate 140, a decrease in detection accuracy can be
prevented.
[0061]
In one aspect, the speaker system 10 described above is applied to a music speaker device as a
single device. Further, in another aspect, the present invention is also applicable to a television
and other video signal output devices. The television can be applied to either a CRT television or
a flat-screen television. The flat-screen television includes, for example, a liquid crystal television,
a plasma television, a television having an organic EL (Electro Luminescence) display, a television
having an FED (Field Emission Display), a SED (Surface-Conduction Electron-emitter Display)
television and the like.
[0062]
In the above description, the MFB speaker 100 corresponds to a so-called cone type speaker
having the cone paper 110 as a diaphragm. However, the diaphragm is not limited to the cone
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paper 110. Moreover, even if it is a flat type or a dome type speaker, the speaker system which
concerns on this Embodiment can be mounted.
[0063]
It should be understood that the embodiments disclosed herein are illustrative and nonrestrictive in every respect. The scope of the present invention is indicated not by the above
description but by the claims, and is intended to include all the modifications within the meaning
and scope equivalent to the claims.
[0064]
It is a figure showing the outline of the composition of the speaker system concerning the
embodiment of the present invention. It is a figure which shows the speaker system of FIG. 1, and
its periphery circuit. It is a figure showing the attachment structure of LED and the
phototransistor in the speaker part of a MFB speaker. It is the general view which looked at the
holding member from the horizontal direction. It is the outline view which looked at a holding
member from the upper surface. It is a figure explaining the attachment aspect of a lightshielding plate. It is the outline view which looked at the speaker part from the horizontal
direction. It is a figure showing the positional relationship of the optical path formed in a holding
member, and a light-shielding plate. It is a figure showing the relationship between the amplitude
of the speaker part of MFB speaker, and the light quantity received by the phototransistor. It is a
figure showing the change of the signal value output from a control circuit. It is an outline view
of a speaker apparatus by which a speaker system concerning an embodiment of the invention is
carried. It is a figure showing the outline of the composition of the conventional speaker system.
Explanation of sign
[0065]
10, 90 speaker system, 100, 900 MFB speaker, 110, 910 cone paper, 120 coil section, 130
magnetic circuit, 140 light shielding plate, 150 LED, 160 phototransistor, 19, 190 control circuit,
210 holding member, 220 hole Part, 230 flange part, 240 center cap, 310 light path, 610 width,
810, 820, 830, 840 curve.
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