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JP2001036985

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2001036985
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
motional feedback (MFB) type speaker system.
[0002]
2. Description of the Related Art FIG. 5 is a block diagram showing a speaker system of
Conventional Example 1 disclosed in, for example, a sightseeing bus catalog "Aero Queen I"
(issued in December 1997) of Mitsubishi Motors Corporation. FIG. 5 shows an example where
the speaker system is mounted on a bus. In FIG. 5, 101 is a bus car body, 102 is a bus car
interior, 103 is a ceiling surface of the bus car interior 102, 104 is a passenger seat, 105 is a
luggage storage provided above the passenger seat 104, 106 is a ceiling surface of the bus car
102 A double drive speaker system (hereinafter referred to as DDSS) installed in a space
sandwiched between 103 and the luggage storage 105, and 107 is a sound reproduction device
installed in the bus car 102.
[0003]
In the DDSS 106, 108 is a main speaker unit, 109 is an auxiliary speaker unit, and 110 is a
sealed cabinet having a main speaker space 110a and an auxiliary speaker space 110b
separately. The main speaker unit 108 is located in the main speaker space 110 a in front of the
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auxiliary speaker unit 109, and the auxiliary speaker unit 109 is located in the auxiliary speaker
space 110 b behind the main speaker unit 108 and fixed to the cabinet 110. . The auxiliary
speaker unit 109 emits, from the rear of the main speaker unit 108, a sound wave whose low
frequency band is synchronized with the sound wave emitted by the main speaker unit 108. For
this reason, the DDSS 106 outputs the reproduced sound in which the sound pressure in the low
frequency range is enhanced by the auxiliary speaker unit 109.
[0004]
In the sound reproducing apparatus 107, 111 is a reproducing device for reproducing data
recorded on a CD or a cassette tape into an acoustic source signal, and 112 is an amplifier for
amplifying the acoustic source signal transmitted from the reproducing device 111. It is an
amplification device.
[0005]
In the conventional example 1 described above, the speaker system is configured by the DDSS
106.
The bus car interior 102 is provided with a large number of DDSSs 106, and the music obtained
by playing back a CD using these multiple DDSSs 106, an announcement obtained by playing
back a cassette tape, etc. Flow to
[0006]
Next, the operation will be described. Data recorded on a CD or the like is reproduced by the
reproduction device 111 into an acoustic source signal. The sound source signal reproduced by
the reproduction device 111 is transmitted to the amplification device 112, amplified to a desired
size, and transmitted to the DDSS 106. When the sound source signal is transmitted to the DDSS
106, a reproduced sound according to the sound source signal is output from the DDSS 106.
[0007]
FIG. 6 is a block diagram showing a speaker system of Conventional Example 2 disclosed, for
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example, in the bus catalog "Aero Midi MJ" (issued in June 1998) of Mitsubishi Motors
Corporation. FIG. 6 shows an example where the speaker system is mounted on a bus. In FIG. 6,
201 is a ceiling surface of the bus body 101, 202 is a ceiling space sandwiched between the
ceiling surface 103 of the bus car 102 and the ceiling surface 201 of the bus body 101, 203 is
located in the ceiling space 202 It is a speaker unit embedded in the ceiling surface 103 of 102.
The speaker unit 203 outputs reproduced sound in which the sound pressure in the low
frequency range conforms to the ceiling space 202. The other components are the same as or
equivalent to those shown in FIG. 5 with the same reference numerals, and thus the detailed
description thereof will be omitted.
[0008]
In the second prior art, the speaker system is composed of the speaker unit 203 and the ceiling
space 202. A large number of speaker units 203 are provided on the ceiling surface 103 of the
bus car interior 102, and the music and the cassette tape obtained by reproducing the CD are
obtained by using the large number of speaker units 203. An announcement etc. flows
throughout the bus interior 102.
[0009]
Next, the operation will be described. As in the case of Conventional Example 1, data recorded on
a CD or the like is reproduced by the reproduction device 111 into an acoustic source signal. The
sound source signal reproduced by the reproduction device 111 is transmitted to the
amplification device 112, amplified to a desired size, and then transmitted to the speaker unit
203. When the sound source signal is transmitted to the speaker unit 203, reproduced sound
according to the sound source signal is output from the speaker unit 203.
[0010]
FIG. 7 is an acoustic characteristic diagram of the speaker system of the first prior art. FIG. 7A
shows an output sound pressure frequency characteristic, and FIG. 7B shows an impedance
characteristic. In FIG. 7A, the vertical axis is sound pressure level (dB) and the horizontal axis is
frequency (Hz), and in FIG. 7B, the vertical axis is impedance (Ω) and the horizontal axis is
frequency (Hz). is there. In the figure, f0 is the lowest resonance frequency, and Q0 is sharpness.
The lowest resonance frequency f0 is a lower limit frequency that the speaker system can
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reproduce. The acoustic characteristic of the speaker system of Conventional Example 2 also
exhibits the same characteristic as that of FIG.
[0011]
In the case of the first prior art, the value of the lowest resonance frequency f0 is a component or
a member constant of a diaphragm that constitutes the main speaker unit 108 and the auxiliary
speaker unit 109 and a supporting system that supports the diaphragm, and further a main
speaker In the case of the second prior art, it is determined by the diaphragm and the supporting
system supporting the diaphragm constituting the speaker unit 203 and the member constant of
the support system, and further, in the case of the ceiling space 202. It depends on the volume
etc. That is, the value of the lowest resonance frequency f0 is determined by the design
specification of the speaker unit, the space volume for the speaker unit, and the like.
[0012]
As described above, according to the speaker system of the first prior art, the auxiliary speaker
unit 109 is provided behind the main speaker unit 108, and the sound pressure in the low
frequency range is set by the auxiliary speaker unit 109. Is configured to output enhanced
playback sound, so two speaker units are required to configure one speaker system. For this
reason, the cabinet 110 which comprises a speaker system was large, and the subject that the
whole speaker system was large occurred. Another problem is that the speaker system is heavy.
Furthermore, when the speaker system is mounted on the bus, there is a problem that the entire
bus becomes heavy and the fuel efficiency deteriorates because the speaker system is heavy.
[0013]
Further, in the speaker system of Conventional Example 1, there is a problem that the value of
the lowest resonance frequency f0 can not be changed after the design specifications of the main
speaker unit 108 and the auxiliary speaker unit 109 and the design specifications of the cabinet
110 are determined. there were.
[0014]
Further, in the speaker system of the prior art example 2, it is necessary to install an in-vehicle
environment device such as an air conditioner in the ceiling space 202, and the height of the bus
body 101 is also limited. The volume of the ceiling space 202 for 203 is limited, and it is not
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possible to secure a sufficient volume of space necessary to emit sound waves in the low
frequency range, and output a reproduced sound in a satisfactory low frequency range There was
a problem that it was impossible.
[0015]
The present invention has been made to solve the above problems, and even after the design
specification of the speaker unit and the space volume for the speaker unit are determined, the
value of the lowest resonance frequency is the value of sharpness. It is an object of the present
invention to provide a speaker system provided with a small and lightweight speaker unit
capable of outputting reproduced sound in a lower frequency range by keeping the lower the
value of.
[0016]
A speaker unit according to the present invention comprises a speaker unit having a drive coil
and a detection coil, and a low frequency component of an acoustic source signal transmitted
from the outside corrected. And an active control unit for transmitting to the drive coil, wherein
the detection coil transmits a detection signal synchronized with the acoustic source signal
transmitted to the drive coil to the active control unit, and the active control unit is for the
acoustic signal The low frequency component of the acoustic source signal is corrected based on
the detection signal so that the lowest resonance frequency and the sharpness obtained from the
impedance characteristic obtained when transmitted to the drive coil have predetermined values.
[0017]
In the speaker unit according to the present invention, the active control unit corrects the low
frequency component of the detection signal, and the control circuit unit transmits it as a
feedback signal, and the feedback signal is added to the acoustic source signal to produce an
acoustic signal. A feedback signal addition unit for transmitting the detection signal such that the
control circuit unit sets the minimum resonance frequency and the sharpness obtained from the
impedance characteristic obtained when the acoustic signal is transmitted to the drive coil to a
predetermined value It corrects the low frequency component of
[0018]
In the speaker unit according to the present invention, the control circuit section corrects the low
frequency component of the detection signal based on the vibration displacement of the
detection coil, and transmits it as the first control signal, and the detection coil The low
frequency component of the detection signal is corrected based on the vibration velocity of the
detection signal, and the low frequency component of the detection signal is corrected based on
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the vibration acceleration of the detection coil. Vibration acceleration detecting means for
transmitting as a control signal of the control signal, and control signal adding means for adding
the first to third control signals transmitted from the detecting means and transmitting to the
feedback signal adding unit as a feedback signal, The low frequency component of the detection
signal is set so that the displacement detection means sets the sharpness obtained from the
impedance characteristic obtained when the acoustic signal is transmitted to the drive coil to a
predetermined value. The vibration velocity detection means corrects the overall level of the low
frequency impedance value in the impedance characteristic without changing the value of the
lowest resonance frequency obtained from the impedance characteristic obtained when the
acoustic signal is transmitted to the drive coil. The low frequency component of the detection
signal is corrected so as to obtain a predetermined height, and the vibration acceleration
detection means has a predetermined value of the lowest resonance frequency obtained from the
impedance characteristic obtained when the acoustic signal is transmitted to the drive coil. As a
result, the low frequency component of the detection signal is corrected.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will
be described below.
Embodiment 1
FIG. 1 is a block diagram showing a speaker system according to Embodiment 1 of the present
invention.
FIG. 1 shows an example in which a speaker system is mounted on a bus.
FIG. 2 is a configuration diagram showing details of an MFB control unit and a speaker unit in the
speaker system according to Embodiment 1 of the present invention.
FIG. 3 is a configuration diagram showing details of a control circuit unit in the MFB control unit
of the speaker system according to the first embodiment of the present invention.
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In the figure, 1 is a bus body, 2 is a bus car, 3 is a ceiling surface of the bus car 2, 4 is a
passenger seat, 5 is a luggage storage provided above the passenger seat 4 and 6 is a ceiling
surface 3 of the bus car 2. A cabinet of sealed specification installed in the space between the
two and the cargo storage area 5, 7 is a speaker unit located in the speaker space 6a of the
cabinet 6 and fixed to the cabinet 6, 8 is a low frequency component of the sound source signal
Are corrected and transmitted to the speaker unit 7 as an acoustic signal. An MFB control unit
(active control unit) 9 is an acoustic reproduction device installed in the bus car 2. The MFB
control unit 8 sets the low frequency component of the sound source signal so that the minimum
resonance frequency f01 and the sharpness Q0 obtained from the impedance characteristic
obtained when the sound signal is transmitted to the speaker unit 7 have predetermined values.
It is a correction.
[0020]
In the speaker unit 7, 11 is a diaphragm, 12 is a voice coil bobbin connected to the diaphragm
11, 13 is a drive coil wound around the voice coil bobbin 12, and 14 is a detection coil wound
around the voice coil bobbin 12. It is. Since the detection coil 14 detects the vibration, it may be
wound around the voice coil bobbin 12 several times, and the winding position may be
anywhere, and may be on the drive coil 13.
[0021]
In the MFB control unit 8, a control circuit unit 21 removes high frequency components of the
detection signal transmitted from the detection coil 14 by a filter, corrects low frequency
components, and transmits it as a feedback signal. A feedback signal addition unit that adds the
feedback signal transmitted from the sound source signal to the acoustic source signal and
transmits it as an acoustic signal. An amplification circuit unit that amplifies the acoustic signal
transmitted from the feedback signal addition unit 22 and transmits it to the drive coil 13 It is.
The control circuit unit 21 sets the minimum resonance frequency f01 and the sharpness Q0
obtained from the impedance characteristic obtained when the acoustic signal after addition
processing in the feedback signal addition unit 22 is transmitted to the drive coil 13 to a
predetermined value. To correct the low frequency component of the detection signal. The
amplification circuit unit 23 is a built-in amplification means.
[0022]
In the control circuit unit 21, the reference numeral 24 detects the vibration displacement of the
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detection coil 14 based on the detection signal transmitted from the detection coil 14, and
corrects the low frequency component of the detection signal based on the vibration
displacement. Vibration displacement detection means transmitted as a control signal, 25 detects
the vibration velocity of the detection coil 14 from the detection signal transmitted from the
detection coil 14, corrects the low frequency component of the detection signal based on the
vibration velocity, and Vibration detection means for transmitting as a control signal of the
sensor, 26 detects the vibration acceleration of the detection coil 14 by the detection signal
transmitted from the detection coil 14, corrects the low frequency component of the detection
signal based on the vibration acceleration, Vibration acceleration detecting means transmitted as
the control signal of No. 3; 27 adds the first to third control signals transmitted from the
respective detecting means 24 to 26; Is a control signal adding means for transmitting the
feedback signal addition unit 22 as.
[0023]
The vibration displacement detection means 24 has a predetermined sharpness Q 0 determined
from the impedance characteristic obtained when the acoustic signal after addition processing in
the control signal addition means 27 and the feedback signal addition unit 22 is transmitted to
the drive coil 13. The low frequency component of the detection signal is corrected to have a
value of.
The vibration speed detection means 25 is also obtained from the impedance characteristic
obtained when the acoustic signal after addition processing in the control signal addition means
27 and the feedback signal addition unit 22 is transmitted to the drive coil 13 and has a value of
the lowest resonance frequency f01. The low frequency component of the detection signal is
corrected so as to make the overall level of the low frequency range impedance value in the
impedance characteristic a predetermined height without changing the The vibration
acceleration detection means 26 also determines the minimum resonance frequency f 01
determined from the impedance characteristic obtained when the acoustic signal after addition
processing in the control signal addition means 27 and the feedback signal addition unit 22 is
transmitted to the drive coil 13. The low frequency component of the detection signal is
corrected to have a value of.
[0024]
Each of the detection means 24 to 26 has a circuit configuration including an active element
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such as an operational amplifier and a passive element such as a resistor or a capacitor. Then, the
speaker constant of the speaker unit 7 to which the circuit constant such as the resistance value
of the resistor used or the capacitance value of the capacitor is applied (the value of the lowest
resonance frequency f01, the value of sharpness Q0, the value of equivalent weight M0 of the
speaker unit 7, etc. In the speaker unit 7 to be applied, the circuit is configured as an optimal
circuit to obtain the desired minimum resonance frequency f01 and the sharpness Q0 by
changing according to the above.
[0025]
In the sound reproducing apparatus 9, numeral 31 denotes a reproducing apparatus for
reproducing data recorded on a CD, a cassette tape or the like into a sound source signal and
transmitting the sound source signal to the MFB control unit 8.
[0026]
In the first embodiment, the speaker system is composed of the speaker unit 7 and the MFB
control unit 8.
Then, a large number of speaker units 7 are provided in the bus car interior 2, and music that
can be obtained CDs, announcements obtained by reproducing a cassette tape, and the like using
the large number of speaker units 7 Flow to
[0027]
Next, the operation will be described. The data recorded on the CD or the like is reproduced by
the reproduction device 31 into an acoustic source signal. The sound source signal reproduced
by the reproduction device 31 is transmitted to the feedback signal addition unit 22 of the MFB
control unit 8. The acoustic source signal transmitted to the feedback signal addition unit 22
passes through the feedback signal addition unit 22 once, is transmitted to the amplification
circuit unit 23, amplified to a desired size, and then transmitted to the drive coil 13 of the
speaker unit 7. It is transmitted. When an acoustic source signal is transmitted to the drive coil
13, the voice coil bobbin 12 vibrates in a piston due to an electromagnetic induction action with
a magnetic field formed by the magnetic circuit, and the vibration causes the diaphragm 11 and
the detection coil 14 to vibrate. When the detection coil 14 vibrates, a signal synchronized with
the sound source signal is transmitted to the MFB control unit 8 as a detection signal.
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[0028]
Of the detection signal transmitted to the MFB control unit 8, high frequency components are
removed by a filter, and only low frequency components are transmitted to the control circuit
unit 21. The detection signal of the low frequency component transmitted to the control circuit
unit 21 is transmitted to the vibration displacement detection means 24, the vibration speed
detection means 25 and the vibration acceleration detection means 26. The detection signal of
the low frequency component transmitted to each of the detection units 24 to 26 is transmitted
to the control signal addition unit 27 as first to third control signals by receiving predetermined
processing described later.
[0029]
The first to third control signals are added by the control signal adding means 27 and
transmitted to the feedback signal adding unit 22 as a feedback signal. The feedback signal is
added to the acoustic source signal by the feedback signal addition unit 22 and transmitted to
the amplification circuit unit 23 as an acoustic signal. The acoustic signal transmitted to the
amplifier circuit unit 23 is amplified to a desired size and then transmitted to the drive coil 13 of
the speaker unit 7. When an acoustic signal is transmitted to the drive coil 13, the voice coil
bobbin 12 vibrates due to the electromagnetic induction action with the magnetic field formed by
the magnetic circuit, the diaphragm 11 vibrates due to the vibration, and the reproduced sound
according to the acoustic signal It is outputted from the speaker unit 7.
[0030]
The operation of each of the detection means 24 to 26 will now be described. The vibration
displacement detection means 24 increases the value of the sharpness Q0 obtained from the
impedance characteristic obtained when the acoustic signal after addition processing in the
control signal addition means 27 and the feedback signal addition unit 22 is transmitted to the
drive coil 13. As described above, the low frequency component of the detection signal is
corrected and transmitted to the control signal adding means 27 as a first control signal. In short,
the detection signal of the low frequency component transmitted to the vibration displacement
detection means 24 is corrected so that the value of the sharpness Q0 obtained from the
impedance characteristic obtained when the acoustic signal is transmitted to the drive coil 13
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becomes high. And transmitted to the control signal adding means 27 as a first control signal.
[0031]
The vibration velocity detection means 25 has a minimum resonance frequency f 01 determined
from the impedance characteristic obtained when the acoustic signal after addition processing in
the control signal addition means 27 and the feedback signal addition unit 22 is transmitted to
the drive coil 13. The low frequency component of the detection signal is corrected so as to raise
the overall level of the low frequency range impedance value in the impedance characteristic to a
predetermined height without changing the value, and transmitted to the control signal addition
means 27 as a second control signal Do. In short, the detection signal of the low frequency
component transmitted to the vibration velocity detection means 25 is an impedance
characteristic without changing the value of the lowest resonance frequency f 01 obtained from
the impedance characteristic obtained when the acoustic signal is transmitted to the drive coil 13
The overall level of the low frequency range impedance value is corrected to rise to a
predetermined height, and transmitted to the control signal adding means 27 as a second control
signal.
[0032]
The vibration acceleration detecting means 26 has a minimum resonance frequency f 01
obtained from the impedance characteristic obtained when the acoustic signal after addition
processing in the control signal adding means 27 and the feedback signal adding portion 22 is
transmitted to the drive coil 13. The low frequency component of the detection signal is
corrected so as to lower the value, and is transmitted to the control signal addition means 27 as a
third control signal. In short, the detection signal of the low frequency component transmitted to
the vibration acceleration detection means 26 is corrected so that the value of the lowest
resonance frequency f01 obtained from the impedance characteristic obtained when the acoustic
signal is transmitted to the drive coil 13 becomes low. And transmitted to the control signal
adding means 27 as a third control signal.
[0033]
That is, the vibration acceleration detection means 26 functions to lower the value of the lowest
resonance frequency f01 obtained from the impedance characteristic, and only by such operation
of the vibration acceleration detection means 26, it is possible to obtain the lowest resonance
frequency f01 in the impedance characteristic. Of the low frequency region and the overall level
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of the impedance value in the low frequency region is lowered. Therefore, the impedance value in
the low frequency region in the impedance characteristic is not changed without changing the
value of the lowest resonance frequency f01 obtained from the impedance characteristic And the
vibration displacement detection means 24 work to increase the value of the sharpness Q0
obtained from the impedance characteristic, thereby improving the damping and at the
frequency around the lowest resonance frequency f01. Increase the output sound pressure level.
[0034]
The detection means 24 to 26 operate as described above, and the first to third control signals
are added by the control signal addition means 27 and transmitted to the feedback signal
addition unit 22 as a feedback signal. Thus, the control circuit unit 21 holds the value of the
sharpness Q0 obtained from the impedance characteristic obtained when the acoustic signal
after the addition processing in the feedback signal addition unit 22 is transmitted to the drive
coil 13, while maintaining the minimum resonance. The low frequency component of the
detection signal is corrected so as to lower the value of the frequency f01, and the feedback
signal is transmitted to the feedback signal adding unit 22 as a feedback signal.
[0035]
Also, the control circuit unit 21 operates as described above, and the feedback signal is added to
the acoustic source signal by the feedback signal addition unit 22 and transmitted as an acoustic
signal to the amplification circuit unit 23 to a desired size. After being amplified and transmitted
to the speaker unit 13, the MFB control unit 8 holds the value of the sharpness Q0 obtained from
the impedance characteristic obtained when the acoustic signal is transmitted to the drive coil
13. The low frequency component of the acoustic source signal is corrected based on the
detection signal so as to lower the value of the lowest resonance frequency f01, and the signal is
transmitted to the drive coil 13 as an acoustic signal.
[0036]
FIG. 4 is a comparison diagram of the acoustic characteristics of the speaker system according to
the first embodiment of the present invention and the acoustic characteristics of the speaker
system of the first conventional example.
FIG. 4A shows a comparison of output sound pressure frequency characteristics, and FIG. 4B
shows a comparison of impedance characteristics.
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In FIG. 4A, the vertical axis is sound pressure level (dB) and the horizontal axis is frequency (Hz),
and in FIG. 4B, the vertical axis is impedance (Ω) and the horizontal axis is frequency (Hz). is
there.
In the figure, curves a and c show the characteristics of the speaker system of Embodiment 1,
and curves b and d show the characteristics of the conventional speaker system. In the figure,
f01 is the lowest resonance frequency of the speaker system of the first embodiment, and f0 is
the lowest resonance frequency of the speaker system of the prior art example 1. Further, in the
figure, X0 is the frequency of the boundary between the low frequency range and the high
frequency range and the boundary between the low frequency range and the high frequency
range in the above description, and the impedance at the lowest resonance frequency f01, f0
Corresponds to the frequency at the point where the peak of H has fallen completely.
[0037]
As apparent from FIG. 4, in the speaker system according to the first embodiment of the present
invention, each detecting means 24 to 26 is configured by using a resistor of an appropriate
resistance value and a capacitor of an appropriate capacitance value. The value of the lowest
resonance frequency f01 becomes lower than the lowest resonance frequency f0 of the speaker
system of the conventional example 1 while holding the value of the sharpness Q0.
[0038]
As described above, according to the first embodiment, the low frequency component of the
sound source signal transmitted from the speaker unit 7 having the drive coil 13 and the
detection coil 14 and the reproduction device 31 is corrected, The speaker system is configured
to include the MFB control unit 8 transmitting to the drive coil 13 as an acoustic signal, and the
detection coil 14 synchronizes with the acoustic source signal transmitted to the drive coil 13 to
the MFB control unit 8 Based on the detection signal, the MFB control unit 8 sets the lowest
resonance frequency f 01 and the sharpness Q 0 obtained from the impedance characteristic
obtained when the acoustic signal is transmitted to the drive coil 13 to a predetermined value.
Since the low frequency component of the sound source signal is corrected, even after the design
specification of the speaker unit 7 and the space volume for the speaker unit have been
determined, sharpening By lowering the value of the lowest resonance frequency f01 while
maintaining the value of the degree Q0, it is possible to obtain a speaker system capable of
outputting reproduced sound in a lower frequency range.
[0039]
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Further, according to the first embodiment, since a plurality of speaker units are not required to
configure the speaker system as in the conventional example 1, a small and lightweight speaker
system can be obtained. effective.
[0040]
Furthermore, according to the first embodiment, since a small speaker system capable of
outputting reproduced sound in a lower frequency range than in the prior art can be obtained, it
is widely used as a video reproducing apparatus for general home use. The standard of sound
reproduction of DVD playback equipment is 5.1ch that can reproduce the low frequency range,
but with the conventional speaker system, the volume of the speaker system required to
reproduce the low frequency range becomes large and the residence is limited It can solve the
problem that it is difficult to install such a speaker system in the environment.
[0041]
In the first embodiment described above, although the in-vehicle speaker system has been
described, the speaker system in which the volume of the cabinet can not be sufficiently secured,
and the speaker system in which reproduction of the low frequency range is required are also
described. Equivalent effects can be obtained by configuring a speaker system with the speaker
unit and the MFB control unit.
[0042]
As described above, according to the present invention, the speaker unit having the drive coil and
the detection coil, and the low frequency component of the acoustic source signal transmitted
from the outside are corrected to be used as the acoustic signal. The speaker system is
configured to include an active control unit transmitting to the drive coil, and the detection coil
transmits to the active control unit a detection signal synchronized with an acoustic source signal
transmitted to the drive coil, and actively controlled The low frequency component of the
acoustic source signal is corrected based on the detection signal so that the section takes on a
predetermined value the lowest resonance frequency and sharpness determined from the
impedance characteristic obtained when the acoustic signal is transmitted to the drive coil.
Therefore, even after the design specifications of the speaker unit and the space volume for the
speaker unit are determined, the value of the lowest resonance frequency is lowered while
maintaining the value of sharpness. By that, the effect can be obtained lightweight speaker
system can be obtained a compact capable of outputting a lower frequency range of the
reproduced sound.
[0043]
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Brief description of the drawings
[0044]
FIG. 1 is a configuration diagram showing a speaker system according to Embodiment 1 of the
present invention.
[0045]
FIG. 2 is a configuration diagram showing details of an MFB control unit and a speaker unit in the
speaker system according to Embodiment 1 of the present invention.
[0046]
FIG. 3 is a configuration diagram showing details of a control circuit unit in an MFB control unit
of the speaker system according to Embodiment 1 of the present invention.
[0047]
FIG. 4 is a comparison diagram of the acoustic characteristics of the speaker system according to
the first embodiment of the present invention and the acoustic characteristics of the speaker
system of the first conventional example.
[0048]
FIG. 5 is a block diagram showing a speaker system according to Conventional Example 1;
[0049]
FIG. 6 is a block diagram showing a speaker system according to Conventional Example 2;
[0050]
FIG. 7 is an acoustic characteristic diagram of the speaker system of Conventional Example 1;
[0051]
Explanation of sign
[0052]
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Reference Signs List 1 bus body, 2 bus car, 3 ceiling surface, 4 passenger seat, 5 luggage storage
space, 6 cabinets, 6 cabinets, 6 a speaker space, 7 speaker unit, 8 MFB control unit, 9 sound
reproduction device, 11 diaphragm, 12 voice coil bobbin, 13 Drive coil, 14 detection coil, 21
control circuit unit, 22 feedback signal addition unit, 23 amplification circuit unit, 24 vibration
displacement detection means, 25 vibration speed detection means, 26 vibration acceleration
detection means, 27 control signal addition means, 31 reproduction equipment , 101 bus body,
102 bus car, 103 ceiling surface, 104 passenger seat, 105 luggage storage, 106 double drive
speaker system, 107 sound reproduction device, 108 main speaker unit, 109 auxiliary speaker
unit, 110 cabinet, 110a main speaker space , 110b auxiliary speakers Use space, 111 playback
device 112 amplifies equipment.
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