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JPH0833093

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DESCRIPTION JPH0833093
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
multi-way speaker apparatus.
[0002]
2. Description of the Related Art In a general speaker unit, it is advantageous to obtain a large
energy (high sound pressure) by increasing the aperture, but for a vibration system support
device such as a dynamic type, for example, the edges and dampers have linearity. Is a
disadvantage in terms of reproduction output in the bass pressure region. On the other hand, in
the small aperture speaker unit, when the sound pressure increases or the frequency of the
reproduction signal decreases, the amplitude of the diaphragm increases and distortion occurs.
[0003]
From these circumstances, a multi-way speaker apparatus is known which uses a large aperture
speaker unit for low frequency reproduction and a small aperture speaker unit for high
frequency reproduction. In this multi-way speaker device, a signal obtained by cutting the high
frequency band of the input audio signal with a low pass filter is applied to a large aperture
speaker unit (woofer), and a signal obtained by cutting the low frequency band of the input audio
signal with a high pass filter The speaker unit (tweeter) with a small diameter is provided. The
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setting of the cutoff frequencies of the low pass filter and the high pass filter, that is, the setting
of the crossover frequency is performed while observing the limits of the woofer and the tweeter.
[0004]
In the case of the 3-way speaker system, a mid-range speaker unit is further used for the
midrange, but the same applies to setting the crossover frequency of the woofer and mid-range
and the crossover frequency of the mid-range and tweeter. .
[0005]
By the way, as shown in FIGS. 8A and 8B, the amplitude of the diaphragm of the speaker unit
increases in inverse proportion to the reproduction frequency and the square of the diaphragm
radius. .
For this reason, when setting the crossover frequency, the margin is set high.
[0006]
For example, for a tweeter unit that can be used up to 1.5 KHz for a sound pressure of 95 dB
(SPL), settings are made such that it is used at 3 KHz or more in consideration of a peak sound
pressure of 105 dB (SPL).
[0007]
That is, for the peak sound pressure which is rarely output, it is necessary to set the crossover
frequency high with some allowance, which sacrifices the linearity at a very small level.
In practice, when a user enjoys stereo sound at home, he often listens at a low level, and in such a
case, the speaker device can not perform sufficiently.
[0008]
SUMMARY OF THE INVENTION In view of such problems, the present invention improves the
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linearity at a very small level, and can enjoy rich musicality even at the time of reproduction at a
low level. Intended to provide.
[0009]
For this reason, in the multi-way speaker apparatus having a plurality of filter means for band
division and a plurality of speaker units to which the output sound signal from each filter means
is supplied, each filter means changes the cutoff frequency Configure to be able to
Then, a variable control signal of the cutoff frequency for each filter means is output according to
the input audio signal level, and crossover frequency control means capable of changing the
crossover frequency by each filter means is provided.
[0010]
Further, the crossover frequency control means changes the crossover frequency by each filter
means to the low frequency side when the input speech signal level is smaller than the
predetermined level.
[0011]
By changing the crossover frequency in accordance with the level of the input audio signal, it is
possible to eliminate the need to sacrifice linearity at a very small level in consideration of the
large level input.
For example, when the input audio signal level is smaller than a predetermined level, by changing
the crossover frequency to the low frequency side, it is possible to maintain good linearity at the
low level.
[0012]
Embodiments The first to third embodiments of the present invention will be described below.
FIG. 1 is a block diagram of a multi-way speaker apparatus according to a first embodiment. In
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this case, the speaker device is a passive type, and the present invention is configured together
with the speaker device and a portion mounted on the power amplifier device of the previous
stage.
[0013]
Reference numeral 1 denotes a power amplifier, 2 denotes a crossover frequency control unit,
and these are mounted in a power amplifier device. The power amplifier 1 amplifies the input
sound signal SA and supplies it to the speaker device. The output of the power amplifier 1 is also
supplied to the crossover frequency control unit 2. The crossover frequency control unit 2
outputs a control signal Sfc according to the level of the audio signal supplied from the power
amplifier 1 and supplies it to the speaker device.
[0014]
The speaker system is composed of a passive low pass filter 3, a low frequency speaker unit
(woofer) 4, a passive high pass filter 5, and a high frequency speaker unit (tweeter) 6.
[0015]
The low-pass component of the audio signal SA is extracted by the low-pass filter 3 and sent to
the low-pass speaker unit 4 to be output as voice.
Also, the high frequency component of the audio signal SA is extracted by the high pass filter 5
and is sent to the high frequency speaker unit 5 to be output as voice.
[0016]
Here, the low pass filter 3 is composed of, for example, coils L1 and L2, capacitors C1 and C2, a
resistor R1 and a relay RY as shown in FIG. 3 (a). The capacitor C2 is inserted into and removed
from the filter circuit by the opening and closing operation of the relay RY, whereby the cutoff
frequency can be varied.
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[0017]
The high pass filter 5 is constituted of, for example, a coil L3, capacitors C3 and C4, a resistor R2
and a relay RY as shown in FIG. 3 (b). The capacitor C4 is inserted into and removed from the
filter circuit by the opening and closing operation of the relay RY so that the cutoff frequency can
be varied.
[0018]
The crossover frequency control unit 2 is composed of, for example, a rectifier circuit 2a, a
comparator 2b and a hold circuit 2c as shown in FIG. The output from the power amplifier 1 is
rectified by the rectifier circuit 2a and supplied to the comparator 2b. The comparator 2b
compares the output of the rectifier circuit 2a with a predetermined reference level and outputs
the result. The comparison result is held and output by the hold circuit 2c until a different
comparison result is obtained, and this is used as the control signal Sfc. The control signal Sfc is a
signal for controlling the relay RY in the low pass filter 3 and the high pass filter 5.
[0019]
That is, the relay RY in the low pass filter 3 and the high pass filter 5 is switched in the
disconnection state when the input audio signal SA is higher or lower than a predetermined level.
Therefore, in this speaker device, the crossover frequency changes when the input sound signal
SA is higher or lower than a predetermined level.
[0020]
That is, for example, when the cutoff frequency of the low pass filter 3 and the high pass filter 5
is set as shown by the solid line in FIG. 4 when the input voice signal SA is higher than a
predetermined level, the input voice signal SA Becomes lower than a predetermined level, each
cutoff frequency is changed as shown by a broken line in FIG. That is, the crossover frequency is
switched between fcrs1 and fcrs2 according to the audio signal level.
[0021]
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As described above, in this embodiment, by shifting the crossover frequency to the low frequency
side when the input audio signal SA is smaller than the predetermined level, good linearity and
resolution can be maintained even at the time of low level reproduction. . Further, since the
change of the crossover frequency corresponds to the detection of the input audio signal SA, this
detection operation is easy and there is an advantage that it can be realized with a simple
configuration.
[0022]
At the time of switching, the timing of attack and recovery is taken to prevent chattering
operation. The crossover frequency control unit 2 may be disposed in the speaker device.
[0023]
FIG. 5 shows a second embodiment. This is an example of an active type speaker device
incorporating a power amplifier. 11 is an active low pass filter, 12 is a power amplifier, 13 is a
low frequency speaker unit, and low frequency components are extracted from the input audio
signal SA by the low pass filter 11 and amplified by the power amplifier 12 to obtain a low
frequency speaker unit 13 Voice output from.
[0024]
Also, 14 is an active low pass filter, 15 is a power amplifier, 16 is a high frequency speaker unit,
high frequency components are extracted from the input audio signal SA by high pass filter 14
and amplified by power amplifier 15 Audio is output from the high frequency speaker unit 16. A
crossover frequency control unit 17 has the same configuration as that of FIG. 2 described above.
[0025]
The low pass filter 11 is composed of, for example, resistors R3 to R8, capacitors C6 to C8, a
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buffer amplifier 18, and a relay RY as shown in FIG. 6 (a). The resistors R4, R6 and R8 are
inserted into and removed from the filter circuit by the opening and closing operation of the
relay RY, whereby the cutoff frequency can be varied.
[0026]
The high pass filter 14 is constituted by, for example, resistors R9 to R14, coils L5 to L7, a buffer
amplifier 19 and a relay RY as shown in FIG. 6 (b). The resistors R10, R12 and R14 are inserted
into and removed from the filter circuit by the opening and closing operation of the relay RY,
whereby the cutoff frequency can be varied.
[0027]
Since each relay RY is supplied with the control signal Sfc from the crossover frequency control
unit 2 as in the first embodiment, each relay RY has a predetermined input audio signal level.
Opening and closing is controlled depending on whether it is smaller or larger.
[0028]
That is, also in this embodiment, the crossover frequency is switched between fcrs1 and fcrs2 as
shown in FIG. 4 in accordance with the input audio signal level.
That is, when the input audio signal SA is smaller than the predetermined level, the crossover
frequency is shifted to the low frequency side, and good linearity at the time of low level
reproduction can be obtained.
[0029]
FIG. 7 shows a third embodiment. This is the case where a digital filter is used. The input speech
signal SA is digitized by the A / D converter 21 and supplied to the low pass filter 22, the high
pass filter 26 and the crossover frequency control unit 30. The low pass filter 22 and the high
pass filter 26 are configured as digital filters by a DSP (digital signal processor) or the like.
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[0030]
Reference numeral 23 is a D / A converter, 24 is a power amplifier, and 25 is a low-pass speaker
unit. The input audio signal SA is digitized and the low-pass filter 22 extracts low-pass
components. The signal is converted back to an analog signal by the / A converter 23, amplified
by the power amplifier 24, and output as sound from the low frequency speaker unit 25.
[0031]
Also, 27 is a D / A converter, 28 is a power amplifier, 29 is a high frequency speaker unit, and
the input audio signal SA is digitized and high pass filter 26 extracts high frequency components,
The analog signal is restored by the D / A converter 27, amplified by the power amplifier 28, and
the high frequency speaker unit 29 outputs the sound.
[0032]
The low pass filter 22 and the high pass filter 26 perform the filter operation by the arithmetic
processing by the DSP, but the cutoff frequency can be changed by changing the operation
coefficient.
Therefore, the crossover frequency control unit 30 determines the input digital data value, that
is, the input audio signal level, obtains a coefficient value corresponding thereto, and outputs it
as the filter operation coefficient k to the low pass filter 22 and the high pass filter Do.
[0033]
That is, in this case, the crossover frequency control unit 30 outputs the coefficient k set
corresponding to the input level, so that the cross as shown in FIG. 4 as in the first and second
embodiments. Variable control of the over frequency is performed, and the same effect can be
obtained.
[0034]
Although the two-way speaker has been exemplified in the above embodiments, the present
invention can be applied to a three-way speaker as well.
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Although the relay RY is used in the first and second embodiments, a semiconductor switch may
be employed instead.
[0035]
When the speaker corresponds to an audio device to be reproduced as digital audio data, the
player side performs level detection at the digital stage of the reproduction signal, and the cutoff
frequency is variably controlled accordingly. It can also be done.
[0036]
As described above, in the multi-way speaker apparatus of the present invention, the
performance of each speaker unit is always good by changing the crossover frequency in
accordance with the input audio signal level. It can be pulled out.
In particular, when the input audio signal level is lower than a predetermined level, by changing
the crossover frequency to the low frequency side, good linearity can be maintained at the time
of low level output, for example, even when listening to music with small sound. Subtle nuances
of the sound are expressed, and it has the effect of being able to enjoy musical rich sounds.
Therefore, it is a highly suitable multi-way speaker device in the case where the listening room is
narrow or when it is considered that the user wants to enjoy music at night.
[0037]
Brief description of the drawings
[0038]
1 is a block diagram of a first embodiment of the present invention.
[0039]
2 is a block diagram of a crossover frequency control unit of the first and second embodiments.
[0040]
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3 is a circuit diagram of a low pass filter and a high pass filter of the first embodiment.
[0041]
It is explanatory drawing of the crossover frequency shift operation ¦ movement by the FIG. 4
Example.
[0042]
5 is a block diagram of a second embodiment of the present invention.
[0043]
6 is a circuit diagram of a low pass filter and a high pass filter of the second embodiment.
[0044]
7 is a block diagram of a third embodiment of the present invention.
[0045]
8 is an explanatory view of the amplitude-frequency characteristics and amplitude-diaphragm
radius characteristics of the speaker unit.
[0046]
Explanation of sign
[0047]
1, 12, 15, 24, 28 Power Amplifier 2, 17, 30 Crossover Frequency Control 3, 11, 22 Low Pass
Filter 5, 14, 26 High Pass Filter 4, 13, 25 Low Pass Speaker Unit 6, 16, 29 High Range speaker
unit 21 A / D converter 23, 27 D / A converter
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