JP2010252004

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DESCRIPTION JP2010252004
An object of the present invention is to make it possible to immediately recognize the fact that a
set frequency characteristic is corrected by an apparatus. SOLUTION: Characteristic adjustment
means for giving a set gain for a predetermined adjustment band to an audio signal, Level
adjustment means for adjusting the level of an output signal of the characteristic adjustment
means to the set level, and instruction When setting the gain or setting the level according to the
correction, the correction value of the characteristic adjustment means is corrected so that the
output level of the level adjustment means does not become equal to or more than the
predetermined value due to the setting. In the frequency characteristic adjusting apparatus
including the control means (steps 32 to 34) for determining whether or not the control means
corrects the set value of the characteristic adjusting means as a result of the determination (step
35) , And an output to notify that (step 36). [Selected figure] Figure 3
Frequency characteristic adjusting apparatus, program, and frequency characteristic adjusting
method
[0001]
The present invention relates to a frequency characteristic adjusting device that adjusts
frequency characteristics of an audio signal, a program that causes a computer to function as
control means in the device, and a frequency characteristic adjusting method suitable for the
device.
[0002]
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FIG. 4 is a block diagram showing the configuration of a conventional on-vehicle audio apparatus.
As shown in the figure, the apparatus includes an apparatus main body 41, an external amplifier
42 for amplifying an audio signal from the apparatus main body 41, and a speaker 43 for
outputting audio based on the audio signal from the external amplifier 42. The apparatus main
body 41 includes an audio unit that outputs an audio signal such as a player and a tuner, a DSP
(digital signal processor) that performs predetermined signal processing on the audio signal from
the audio unit, and the audio unit and DSP. It has a control unit to control. The DSP constitutes an
equalizer that adjusts frequency characteristics as predetermined signal processing.
[0003]
In the DSP, when the gain is set to increase the level for a predetermined adjustment band by the
equalizer, in order to prevent the occurrence of a clip, the DSP internally reduces the volume in
advance by an amount corresponding to the increase of the level. Is set as For this reason, the
volume that drops in the DSP is restored by the electronic volume outside the DSP. In this case,
the level of the audio signal output from the apparatus main body 41 through the electronic
volume is larger by the set gain than in the flat state in which the frequency characteristic is not
adjusted, so the maximum to the external amplifier 42 There is a possibility that it exceeds the
effective value MXV [Vrms] of the allowable input. If the output level of the device body 41
exceeds MXV [Vrms], the output sound from the speaker 43 may be broken or the external
amplifier 42 may be damaged. Therefore, in order to cope with such inconveniences, it has
conventionally been taken to limit the range of the gain setting value in the equalizer of the DSP
and the volume setting value of the electronic volume to a range in which no problem occurs.
[0004]
FIG. 5 shows an example of a measure for limiting such a setting range in advance. In this
example, the range of the gain setting value in the equalizer and the range of the volume setting
value of the electronic volume are limited. 51 in the figure is an equalizer curve (EQ curve)
representing the frequency characteristic of the gain given by the equalizer, and 52 is a line
showing the level corresponding to the effective value MXV [Vrms] of the maximum allowable
input to the external amplifier 42. In the figure, the relationship between the equalizer curve 51
and the line 52 corresponding to each volume setting value indicated in the "Vol operation"
column for the electronic volume in which the volume setting value of 0 to 40 steps can be set is
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"EQ curve". It is indicated in the column.
[0005]
As shown in the figure, when the volume setting value (gain) of the electronic volume increases,
the level indicated by the line 52 decreases. However, since the range of the gain setting value in
the equalizer and the range of the volume setting value of the electronic volume are limited so as
not to exceed the effective value MXV [Vrms] of the maximum allowable input to the external
amplifier 42, FIG. It is possible to prevent the level of the equalizer curve from exceeding the line
52 without having to use the correction function for the equalizer curve as shown in FIG. That is,
within the limited setting range, the effective value of the input level to the external amplifier 42
is less than or equal to the effective value MXV [Vrms] of the maximum allowable input.
[0006]
FIG. 6 shows another example of preventing the output level of the device main body 41 from
exceeding the effective value MXV [Vrms] of the maximum allowable input to the external
amplifier 42. In this example, the setting is accepted without limiting the settable range of the
gain setting value in the equalizer and the volume setting value of the electronic volume in
advance, and the output level of the apparatus main body 41 is the maximum to the external
amplifier 42 according to the setting value. If the effective input value MXV [Vrms] of the
allowable input is exceeded, the gain setting value in the equalizer is corrected. That is, as shown
in the figure, when the level in the equalizer curve 51 exceeds the line 52, the gain setting value
in the equalizer is corrected so as not to exceed the line 52. When such correction of the
equalizer curve is made, the user can know that by displaying a predetermined screen and
confirming the gain characteristics of the equalizer.
[0007]
As a technique related to the equalizer function by the DSP, for example, when adjusting the
frequency characteristic of the audio signal by the DSP, there is known a technique in which the
gain of the audio signal is reduced when a clip occurs (see FIG. For example, refer to Patent
Document 1). In this technique, when the gain is lowered, the user changes the position of the
slider for setting the gain of the audio signal on the predetermined setting screen accordingly
(paragraph 0014 of Patent Document 1) , 0025).
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[0008]
Further, as a technique related to the equalizer, there is known a technique of an automatic
equalizer that automatically corrects the level of the audio signal of each band based on the level
of each band detected by the microphone (for example, see Patent Document 2). In this
technique, in the automatic equalizer mode, if there is a band out of the respective bands where
the correction amount exceeds the correctable range, an alarm sound is output and a display
indicating the band is performed, and the level is increased or decreased. In addition, a display
indicating which one is out of the correctable range is also displayed. Alternatively, in the same
automatic equalizer mode, when the correction amount exceeds the correctable range for all
bands, an alarm sound is issued and a message to that effect is also known (for example, patent
document 3).
[0009]
Further, as a technique for giving a warning at the time of reproduction, in a reproduction device
such as a CD player, a set volume is stored and when reproduction is started, if the set volume is
equal to or higher than a predetermined level, reproduction is not started for a predetermined
period. There is known one that outputs a warning (see, for example, Patent Document 4).
[0010]
JP-A-2002-151975 JP-B-06-032541 JP-B-06-032540 JP-A-2007-250062
[0011]
However, according to the prior art shown in FIG. 5, the ranges of the gain setting value of the
equalizer and the setting value of the electronic volume are limited in advance to a range not
exceeding the effective value MXV [Vrms] of the maximum allowable input to the external
amplifier. Therefore, the dynamic range of the audio signal is reduced, and the performance of
the DSP can not be fully utilized.
[0012]
On the other hand, according to the prior art shown in FIG. 6, when the equalizer curve set by the
user is corrected by the apparatus, the user can not recognize that the correction has been made.
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Alternatively, the user can only display a predetermined screen and can recognize that the
correction is made only by confirming the gain characteristics.
[0013]
SUMMARY OF THE INVENTION An object of the present invention is, in view of the problems of
the prior art, to allow a frequency characteristic adjusting device to immediately recognize that
the set frequency characteristic is corrected by the device. .
[0014]
In order to achieve this object, according to a first aspect of the present invention, there is
provided a frequency characteristic adjusting apparatus comprising: characteristic adjusting
means for applying a set gain for a predetermined adjustment band to an audio signal; Level
adjustment means for adjusting the level to the set level, and when setting the gain or setting the
level according to the instruction, the output level of the level adjustment means is equal to or
more than a predetermined value due to the setting Control means for determining whether or
not to correct the set value of the characteristic adjustment means, and the control means
corrects the set value of the characteristic adjustment means as a result of the determination.
When it is performed, an output for notifying that effect is performed.
[0015]
The frequency characteristic adjusting apparatus according to a second aspect of the present
invention is the frequency characteristic adjusting apparatus according to the first aspect,
wherein the predetermined adjustment band is plural, and the characteristic adjusting means
applies a gain set for each adjustment band. The means determines whether or not to correct the
set value for each adjustment band, and the control means sets the set value for each set value of
the level adjustment means and for each adjustment band. Storing a threshold value relating to
the set value of the characteristic adjustment means, which serves as a reference for determining
whether or not to perform the correction, wherein the threshold value causes the output level of
the level adjustment means to exceed the predetermined value It is characterized in that it is
determined to be a value that falls within a range not included and that is a threshold value of an
adjustment band that is separated from a predetermined center frequency.
[0016]
The frequency characteristic adjusting apparatus according to a third aspect of the present
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invention is the frequency characteristic adjusting apparatus according to the second aspect,
wherein the control means corresponds to the setting value of the adjustment band when
determining that the setting value is to be corrected for each adjustment band. The set value is
corrected by replacing the threshold value.
[0017]
A program according to a fourth aspect is characterized in that the computer is caused to
function as control means in the frequency characteristic adjusting device according to any one
of the first to third aspects.
[0018]
The frequency characteristic adjusting method according to a fifth aspect of the present
invention is characterized in that the characteristic adjusting step applies a set gain to the audio
signal with respect to a predetermined adjustment band, and the level adjusting means is the
characteristic adjusting means. When the level adjustment step of adjusting the level of the
output signal to the set level, and the control means perform the setting of the gain or the setting
of the level according to the instruction, the setting of the level adjustment means Determining
the correction of the set value of the characteristic adjusting unit so that the output level does
not exceed the predetermined value, and the control unit adjusts the characteristic as a result of
the determination. In the case of correcting the set value of the means, it is characterized by
comprising an output step of performing an output for notifying that effect.
[0019]
According to the present invention, when the set frequency characteristic is corrected by the
device, it can be recognized immediately.
[0020]
It is a block diagram showing composition of a car-mounted audio system concerning one
embodiment of the present invention.
It is a figure which shows the mode of correction ¦ amendment of the equalizer curve in the
apparatus of FIG.
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It is a flowchart which shows the correction process of the equalizer characteristic in the
apparatus of FIG.
It is a block diagram which shows the structure of the vehicle-mounted audio apparatus based on
a prior art example.
FIG. 5 illustrates an example of measures to prevent exceeding the maximum allowable input to
an external amplifier in the device of FIG. 4;
FIG. 5 illustrates another example of measures to prevent exceeding the maximum allowable
input to the external amplifier in the device of FIG. 4;
[0021]
FIG. 1 is a block diagram showing the configuration of an on-vehicle audio apparatus according
to an embodiment of the present invention.
As shown in the figure, the apparatus includes an apparatus body 10, an external amplifier 20
for amplifying an audio signal from the apparatus body 10, and a speaker 30 for outputting
audio based on the audio signal from the external amplifier 20.
The apparatus body 10 includes an audio unit 11 which outputs an analog audio signal by a
player, a tuner, etc., an A / D converter 12 which converts an analog audio signal from the audio
unit 11 into a digital audio signal, and an A / D converter 12. DSP (Digital Signal Processor) 13
having a function of performing predetermined signal processing on digital audio signals of D / A
converter 14 for converting digital audio signals from DSP 13 into analog audio signals, D / A
conversion Electronic volume 15 that adjusts the volume of the analog audio signal from the
mixer 14 and outputs it to the external amplifier 20, the beep output unit 16 that outputs the
audio signal of the beep to the external amplifier 20, and the control unit 17 that controls each
part of the device Equipped with
[0022]
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The DSP 13 implements an equalizer 13a that applies a set gain for a predetermined adjustment
band as realizing the function of performing predetermined signal processing.
For the electronic volume 15, the volume setting value for each step can be set from 0 to 40.
When the audio unit 11 has a function of outputting a digital audio signal, the signal is directly
supplied to the DSP 13 without passing through the A / D converter 12.
[0023]
The control unit 17 gives gain setting values and the like of each adjustment band in the
equalizer 13a to the DSP 13 in order to use the equalizer function of the DSP 13 in accordance
with an instruction from the user. At this time, in order to prevent the generation of a clip, the
DSP 13 instructs the DSP 13 to lower the volume by an amount corresponding to the increase of
the level according to the gain setting value to be applied, and the electronic volume 15 returns
to the original volume. I will tell you. In this case, the level of the audio signal output from the
apparatus main body 10 is larger by the gain setting value to be applied compared to the flat
state in which the frequency characteristic is not adjusted by the equalizer 13a. The maximum
permissible input rms value MXV [Vrms] may be exceeded. The maximum allowable input is the
maximum input voltage that can be amplified without distorting the signal. As the volume setting
value of the electronic volume 15 is larger, and as the gain setting value of the equalizer 13a is
larger, the possibility of exceeding the maximum allowable input MXV [Vrms] increases.
[0024]
If the level of the audio signal input to the external amplifier 20 exceeds the maximum allowable
input MXV [Vrms], the output sound from the speaker 33 may be broken or the external
amplifier 32 may be damaged. Therefore, the equalizer curve in the equalizer 13a is corrected so
that the level of the audio signal input to the external amplifier 20 does not exceed the maximum
allowable input MXV [Vrms].
[0025]
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FIG. 2 shows how the equalizer curve is corrected. In the figure, reference numeral 21 denotes an
equalizer curve (EQ curve) by the equalizer 13a, and reference numeral 22 denotes a line
indicating a level corresponding to the maximum allowable input MXV [Vrms] to the external
amplifier 20. In the figure, the relationship between the equalizer curve 21 and the line 22
corresponding to each setting value shown in the "Vol operation" column for the electronic
volume 15 is shown in the "EQ curve" column.
[0026]
As shown in the drawing, as the volume setting value of the electronic volume 15 increases, the
level indicated by the line 22 decreases, and as the volume setting value decreases, the level of
the line 22 increases. At that time, when the volume setting value is large and 30 or 40, a part of
the equalizer curve 21 exceeds the level of the line 22. In that case, since the effective value of
the output of the DSP 13 exceeds the maximum allowable input MXV [Vrms] to the external
amplifier 20, the control unit 17 prevents the equalizer curve 21 from exceeding the level of the
line 22. Correct the gain setting value of 13a. At this time, in order to notify the user that the
gain setting value has been corrected, the beep sound output unit 16 outputs an audio signal of a
beep sound to the external amplifier 20.
[0027]
FIG. 3 is a flowchart showing such correction processing of the equalizer characteristic. The
correction process is performed by the control unit 17 in accordance with a predetermined
program. When the correction process is started, the control unit 17 first sets the setting value of
the electronic volume 15 or the setting value of the equalizer 13a until the correction process is
ended (step 31) in the process loop including steps 31 to 33. Monitor whether changes have
been made (steps 32 and 33).
[0028]
During this time, if it is detected in step 32 that the setting value of the electronic volume 15 has
been changed, or if it is detected in step 33 that the equalizer setting value has been changed, the
process proceeds to step 34 and the setting value is changed. It is determined whether or not the
effective value of the input level to the external amplifier 20 exceeds the maximum allowable
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input MXV [Vrms]. This determination is based on, for example, the relationship between the
sound volume setting value of the electronic volume 15 previously checked and stored in the
control unit 17, the gain setting value for each adjustment band in the equalizer 13a, and the
maximum allowable input MXV [Vrms]. Can be done.
[0029]
If it is determined in step 34 that the maximum allowable input MXV [Vrms] is not exceeded, the
process returns to step 31. If it is determined that the maximum allowable input MXV [Vrms] is
exceeded, the gain setting value in the equalizer 13a is corrected in step 35 so as not to exceed
the maximum allowable input MXV [Vrms]. This correction can be performed based on the
relationship stored in the control unit 17 described above. Further, in step 36, a beep sound is
output, and the process returns to step 31. If it is determined in step 31 that the correction
process is to be ended due to a change in situation or the like, the correction process is ended.
[0030]
According to the present embodiment, the effective value of the input level to the external
amplifier 20 does not exceed the maximum allowable input MXV [Vrms] due to the change of the
setting value of the electronic volume 15 or the equalizer 13a. Since the beep sound is output
when the set value is corrected, the user can know in real time that the set value of the equalizer
13a is corrected.
[0031]
Further, since the range of possible setting values in the equalizer 13a and the electronic volume
15 is not limited in advance not to exceed the maximum allowable input MXV [Vrms] as in the
conventional case of FIG. 5, the performance of the DSP 13 is maximized. Can be used to
[0032]
The present invention is not limited to the above embodiment, and can be appropriately modified
and implemented.
For example, although not mentioned above, the determination in step 34 of FIG. 3 is performed
for each adjustment band, and when it is determined that there are a plurality of bands exceeding
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the maximum allowable input MXV [Vrms], each band in step 35 Correction of the set value, and
at that time, the set value of the band in which the change in the audibility is not noticeable,
more specifically, the set value of the band farther from the center frequency of the
predetermined middle band is preferentially corrected. Good.
That is, for each adjustment band, the threshold value is the maximum allowable input MXV for
each adjustment band, which serves as a reference for determining whether to correct the gain
setting value of the equalizer 13a for each volume setting value of the electronic volume 15.
Within a range where values do not exceed [Vrms], and as the adjustment band is farther from
the center frequency, the value is set to be lower. Then, when updating the volume setting value
of the electronic volume 15 or the gain setting value of the equalizer 13a, if the gain setting
value of each adjustment band corresponding to the volume setting value after the updating
exceeds the corresponding threshold, the gain A correction may be made to replace the set value
with the threshold.
[0033]
Further, although not mentioned above, when the on-vehicle audio device has a function of
displaying the gain setting value and the equalizer curve in the DSP 13 on a predetermined
equalizer screen and accepting the change of the gain setting value via this screen, The equalizer
setting value corrected in step 35 is not reflected on the screen, and a display based on the gain
setting value not corrected is displayed on the screen, and the change of the gain setting value is
accepted in the display state. You may do so.
[0034]
10, 41: device body, 11: audio unit, 12: A / D converter, 13: DSP, 13a: equalizer, 14: D / A
converter, 15: potential volume, 16: beep sound output unit, 17: Control part, 20, 42: Electronic
volume, 30, 43: Speaker, 21, 51: Equalizer curve, 22, 52: Line which shows a level.
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