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JPH0262192

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DESCRIPTION JPH0262192
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
on-vehicle low-frequency correction device for improving the acoustic characteristics of the
interior of a car. 2. Related Art In recent years, a low-frequency reproduction dedicated speaker
system for vehicle use low-frequency correction devices is mainly used as being effective in
improving the vehicle interior acoustic characteristics, but in combination with a conventional
reproduction device having no correction device At present, the adjustment of the detailed
reproduction frequency band to be adapted to the vehicle interior space different in shape and
shape is not made in view of the configuration. A conventional on-vehicle low-frequency
correction device will be described below. FIG. 7 shows a low frequency reproduction system as
an example of a conventional low frequency correction device for a vehicle. 1 is a reproduction
apparatus such as a car radio, a car tape deck, a car compact disc player, 2 is a mixing circuit, 3
is a band pass filter, 4 is an amplifier, and 5 is a speaker. FIG. 8 is an amplitude characteristic of
the band pass filter 3. The operation of the on-vehicle low frequency band correction device
configured as described above will be described below. First, the right and left signals sent from
the playback device 1 are mixed by the mixing circuit 2, limited to a low device whose center
frequency is 50 to 100 Hz by the band pass filter 3, amplified by the amplifier 4 and speaker
Played in six. As a result, the low device which is insufficient only with the reproduction device
without the low range correction device increases the sound pressure because the reproduction
sound from the speaker 6 is added, and the car interior sound pressure is flat to the low region
with balanced with middle and high sound reduction. Frequency characteristics are obtained.
However, in the above-described conventional configuration, the characteristic of the band pass
filter 3 is symmetrical with respect to the frequency at which the amplitude is maximum as
shown in FIG. Even if you try to raise the sound pressure of 1501-1z or more included in the
base of the instrument to 1 dB to 2 dB, the sound pressure rises over the entire reproduction
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frequency band of the band pass filter 3, and 1 unnecessary frequency The sound pressure at the
required frequency will not change at all relatively since the sound pressure rises. In addition,
even if you try to increase the sound pressure in the vicinity of 200) + z which is buried in the
road noise of the car when the center frequency is set to 60H2 on the acoustic characteristics of
the interior of the car, the same result as above is obtained. The target asymmetric amplitude
characteristic or frequency characteristic can not be obtained. As described above, the low-pass
correction apparatus having the configuration using the current band pass filter 3 has a
disadvantage that effective correction can not be performed.
SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional
problems, and an object of the present invention is to provide an on-vehicle low band correction
device having an asymmetric amplitude characteristic. Means for Solving the Problem In order to
achieve this object, the vehicle low-pass correction device of the present invention is configured
by combining the characteristics of a band pass filter for limiting a reproduction frequency band,
a high pass filter and a low pass filter From a filter configured such that the low and high
frequencies are asymmetric with respect to the center frequency at which the characteristics of
the filter limit the band, an amplifier for amplifying the signal from the filter, and a speaker for
reproducing the signal from the amplifier It is comprised. Operation With this configuration, it is
possible to realize the characteristics of a band pass filter having asymmetric amplitude
characteristics. Embodiment An embodiment of the present invention will be described with
reference to the drawings. FIG. 1 shows the configuration of an on-vehicle low band correction
device according to an embodiment of the present invention. In FIG. 1, 6 is a reproduction
apparatus such as a car radio, a car tape digital, a car compact disc player, 7 is a mixing circuit, 8
is a high pass filter, 9 is a low pass filter, 1 o is an amplifier, and 11 is a speaker. The operation
of the on-vehicle low frequency band correction device configured as described above will be
described below. First, the right and left signals sent from the playback device 6 are mixed by the
mixing circuit 7, and the ultra low pass filter having an amplitude characteristic shown in FIG. It
is cut by the inclination of. The stem function of the high pass filter 8 is expressed by the
following equation. W: angular frequency + CI + 02: capacitor + R ++ R 2 + Rr, Rs: resistance, Vi:
input voltage, vo: output M pressure The low cutoff frequency of this high pass filter 8 and QH of
the circuit showing the sharpness of resonance Formula% Formula% Here, when Q of the circuit
is 1 or more, as shown in FIG. 2, it is possible to have a peak in the amplitude characteristic in
the vicinity of the reduction cutoff frequency. The signal passed through the high pass filter 8 is
cut at a frequency of 1so lz or more at an inclination of -12 dB / octave by the low pass filter 9
having the amplitude characteristic shown in FIG. The system function of this low pass filter 9 is
expressed by the following equation. Also, S = jw, j = J: T, W: angular frequency 05, C4: capacitor
+ R5 * 4: resistance vx: input voltage, VY: output voltage The high-pass cutoff frequency of this
low-pass filter 9 The Qt of the circuit showing the sharpness of the resonance is given by the
following equation%% where the low cutoff frequency of the high pass filter 8 is 60 Hz and the
QH of the circuit showing the sharpness of the resonance is 3.0 G + = 0.1 pF, C 2 = 0.1 pF.
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R, -33 Ω, R2 = 22 Ω, Rp-39 Ω, R8 = 15 Ω and capacitors and resistances are set, and the high
frequency cutoff frequency of the low pass filter 9 is 150 Hz% resonance Set the constant of the
resistor and capacitor with Ω at R5 = 47, Ω at R4 = 47, Ω at 05 = 0.027 μF, Ca ′ ′ ′ ′ ′
′ ′ ′ ′ ′ ′ ′ ′ 0. . The amplitude characteristic of the high pass filter 8 of this toki, the
amplitude characteristic of the low pass filter 9, and the amplitude characteristic passing through
the high pass filter 8 and the low pass filter 9 are shown in FIG. As can be seen by comparison
with FIG. 2, the overall characteristic of FIG. 6 clearly shows an asymmetric amplitude
characteristic or frequency characteristic. Specifically, at a frequency of 150 Hz or more, the
amplitude is increased by 1 to 2 dB as compared with the symmetrical band pass filter shown in
FIG. As described above, when a signal having an asymmetric amplitude characteristic is added to
the amplifier 1 o and reproduced by the speaker 11, low-frequency sound is compared with a
conventional low-frequency correction device for vehicle having symmetrical amplitude
characteristics. It becomes possible to increase the sound pressure around 200 Hz, which tends
to be buried due to the fine adjustment of the sound pressure of 150 Hz or more, which is
important for reproduction, vehicle cabin characteristics and vehicle road noise, etc., and uniform
sound pressure frequency characteristics can be obtained. It can be made natural and easy to
hear. As described above, by setting the Actig high pass filter and Acty glow pass filter in
combination with a filter that limits the frequency band of the signal to be reproduced, it is
possible to obtain an asymmetric amplitude characteristic, and a good car Indoor sound pressure
frequency characteristics can be obtained. In the first embodiment, other constants may be used
for the capacitor and the resistor to determine the center frequency of the high pass filter 8 and
the QH indicating the sharpness of the resonance. In addition, in determining the center
frequency of the low pass filter 9 and QL indicating the sharpness of resonance, other constants
may be used for the resistor and the capacitor. As described above, according to the present
invention, a band pass filter having asymmetric amplitude characteristics is provided by
providing a high pass filter and a low pass filter in a filter for limiting the frequency s range of a
signal to be reproduced. It is possible to realize an excellent on-vehicle low-frequency correction
device that can
[0002]
Brief description of the drawings
[0003]
1 is a block diagram of an on-vehicle low band correction device according to an embodiment of
the present invention, FIG. 2 is an amplitude characteristic diagram of the high pass filter of FIG.
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1, and FIG. 3 is an amplitude characteristic diagram of the low pass filter of FIG. 4 is an electric
circuit diagram of the high pass filter of FIG. 1, FIG. 5 is an electric circuit diagram of the low
pass filter of FIG. 1, and FIG. 6 is a combination of the high pass filter, the low pass filter and
both in the embodiment of the present invention. FIG. 7 is a block diagram of a conventional onvehicle low-pass correction device, and FIG. 8 is an amplitude characteristic diagram of the band
pass filter of FIG.
6 · · · · · · · · playback equipment, 7 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·. 11 ..... speaker. Name of
agent Attorney Attorney Shigefumi Other 1 person Regenerator 5 Fig. Fig. 図 周 孜 孜 − − フ □
フ bypass filter フ low-pass filter renal one----- --Composite characteristics
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