JP2012182648

Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2012182648
An object of the present invention is to suppress power consumption of an amplifier by removing
low-frequency sound signals even when a predetermined woofer amplifier is not provided.
SOLUTION: A volume adjustment unit 6 that adjusts the volume of an input sound signal, a high
pass filter 5 that attenuates low frequency components of the input sound signal, and a volume
threshold adjusted by the volume adjustment unit 6 are volume thresholds When it is determined
that the volume adjusted by the volume adjustment unit 6 is lower than the volume threshold by
the power saving control unit 3 that determines whether or not the volume is less than, the input
sound signal is And a signal control unit 4 that outputs the high-pass filter 5. [Selected figure]
Figure 1
Amplifier, mobile information device and power saving method for amplifier
[0001]
The present invention relates to an amplifier, and more particularly to a technique for
suppressing power consumption.
[0002]
2. Description of the Related Art Conventionally, audio that can reproduce wide-band sound has
been distributed, including a plurality of speakers for reproducing sound from low to high
frequencies.
09-05-2019
1
Such audio makes it possible to reproduce clear and powerful music that is close to the actual
sound, but on the other hand, the power consumption of the amplifier and speaker is greater as
the sound of wide band is reproduced. Are known.
[0003]
On the other hand, when such audio is provided in a moving body (for example, an automobile),
depending on the volume at which the user is listening, sounds in a band close to the frequency
of driving noise and tire running noise generated when the vehicle is traveling. I can not hear
you. In particular, when driving a car, noise is often at a low frequency, and in the case of an
audio capable of reproducing this low frequency, the above-mentioned effect may be reduced to
the same level as that of normal audio. Results in wasted consumption.
[0004]
Further, in recent years, development of electric vehicles has progressed, and since power
consumption of the entire electric vehicle affects travel distance, it is desirable to suppress power
consumption even in an audio or an amplifier mounted on the electric vehicle.
[0005]
As a countermeasure, in Patent Document 1, in an electronic musical instrument provided with a
subwoofer amplifier for amplifying a bass signal or a sound effect, there is a technology for
stopping the function of the subwoofer amplifier when the volume is lower than a predetermined
level. It is disclosed.
[0006]
JP 2007-81812 A
[0007]
However, the technique disclosed in Patent Document 1 described above has a problem that it
can not be applied when the subwoofer amplifier is not provided.
[0008]
The present invention has been made to solve the above-mentioned problems, and it is possible
to suppress the power consumption of the amplifier by removing low-frequency sound signals
09-05-2019
2
even when the predetermined woofer amplifier is not provided. To aim.
[0009]
The amplifier according to the present invention includes a volume adjustment unit that adjusts
the volume of an input sound signal, a high pass filter that attenuates low frequency components
of the input sound signal, and a volume adjusted by the volume adjustment unit. When it is
determined that the volume adjusted by the volume adjustment unit is less than the volume
threshold by the determination unit that determines whether or not the volume threshold is less
than the volume threshold, the input sound signal is used as the high-pass filter And an output
signal control unit.
[0010]
According to the present invention, power saving of the amplifier can be achieved, and audio
output natural in hearing can be realized.
[0011]
FIG. 2 is a block diagram showing configurations of an amplifier and a mobile information device
according to Embodiment 1.
7 is a flowchart showing the operation of a mobile information device including an amplifier
according to the first embodiment.
FIG. 7 is a block diagram showing the configuration of an amplifier and mobile information
device according to a second embodiment.
10 is a flowchart showing an operation of a mobile information device including an amplifier
according to a second embodiment.
FIG. 13 is a block diagram showing the configuration of an amplifier and mobile information
device according to a third embodiment.
09-05-2019
3
10 is a flowchart showing the operation of the on-vehicle audio device including the amplifier
according to the third embodiment.
[0012]
Embodiment 1
FIG. 1 is a block diagram showing a configuration of an amplifier and a mobile information
device according to a first embodiment of the present invention.
In FIG. 1, the amplifier 1 includes a moving speed calculation unit 2, a power saving control unit
(determination unit) 3, a signal control unit 4, a high pass filter 5, a volume adjustment unit 6,
and a speaker amplifier 7. Further, the mobile information acquisition unit 21, the seat position
detection unit 22, the audio unit 23, the speaker 24 and the notification unit 25 are connected to
the amplifier 1 to configure a mobile information device. The mobile information device is, for
example, an in-vehicle navigation device or an in-vehicle audio device.
[0013]
Details of each configuration shown in FIG. 1 will be described. The moving body information
acquisition unit 21 acquires an acceleration of the moving body, a vehicle speed pulse, and the
like. The movement speed calculation unit 2 calculates the movement speed of the moving body
from the acceleration and the vehicle speed pulse acquired by the moving body information
acquisition unit 21. For example, when the mobile object is an automobile, the seating position
detection unit 22 detects a seat on which a user or a passenger (hereinafter referred to as a user)
is seated among the seats of the automobile.
[0014]
The audio unit 23 is the speaker 24 located in the vicinity of the other seats excluding the seat
where the user's seat is detected in the seating position detection unit 22 or the farthest from the
seat where the user's seat is detected The speaker 24 located near the seat is selected as the
speaker 24 to be set in the power saving state. The audio unit 23 also outputs the volume value
09-05-2019
4
set by the user via the operation input unit (not shown) to the volume adjustment unit 6.
[0015]
The power saving control unit 3 sets the sound volume threshold of the speaker amplifier 7
according to the moving speed of the moving object calculated by the moving speed calculation
unit 2, and acquires the set sound volume threshold and the current speaker amplifier acquired
from the sound volume adjusting unit 6. Compare with the volume value of 7. When the current
volume value of the speaker amplifier 7 is equal to or higher than the volume threshold, the
control information instructing the transition of the speaker 24 selected to be able to be set to
the power saving state in the audio unit 23 to the power saving state is It is generated and output
to the signal control unit 4.
[0016]
Among the plurality of audio signals input from the audio unit 23 based on the control
information input from the power saving control unit 3, the signal control unit 4 has an audio
signal output from the speaker 24 to be shifted to the power saving state. In this case, the audio
signal is output to the high pass filter 5 as an attenuated audio signal. On the other hand, the
audio signal output from the speaker 24 not to shift to the power saving state is output to the
volume adjustment unit 6 as an audio signal.
[0017]
The high pass filter 5 attenuates an audio signal having a preset cutoff frequency or less with
respect to the attenuated audio signal input from the signal control unit 4. The volume adjuster 6
attenuates or amplifies the attenuated audio signal input from the high pass filter 5 and the
normal audio signal input from the signal controller 4 according to the volume value set by the
audio unit 23. The speaker amplifier 7 drives the speaker 24 and outputs the audio signal
adjusted by the volume adjustment unit 6 from the speaker 24 as a sound.
[0018]
09-05-2019
5
When the notification unit 25 acquires from the power saving control unit 3 control information
to shift any of the speakers 24 to the power saving state, the notification unit 25 notifies the user
that the speaker 24 is operating with power saving. The notification method can be configured in
various ways. For example, a light emitting element such as an LED is turned on, a message such
as Operating in a power saving state is output by voice, or a display unit of the audio unit 23
or navigation unit A message such as Operating in power saving mode is displayed using
(not shown). Further, notification may be made so that the speaker 24 transitioning to the power
saving state can be identified, or notification that the transition to the power saving state is
generally made may be made.
[0019]
Next, the operation will be described. FIG. 2 is a flowchart showing the flow of the operation of
the mobile information device including the amplifier of the first embodiment. When the seating
position detection unit 22 detects the seating position of the user (step ST1), the audio unit 23
refers to the seating position detected in step ST1 and locates near the seat where the user is not
seated. The speaker 24 is selected as the speaker 24 to be shifted to the power saving state (step
ST2). The moving body speed calculation unit 2 calculates the moving speed of the moving body
from the moving body information acquired by the moving body information acquisition unit 21
(step ST3). The power saving control unit 3 calculates the volume threshold based on the moving
speed of the moving object calculated in step ST3 (step ST4), and the new volume threshold
calculated in step ST4 is a predetermined time ago (for example, one minute ago) It is determined
whether or not the difference between the calculated sound volume threshold value and the
calculated sound volume threshold value is within a predetermined range (step ST5).
[0020]
In step ST4, the power saving control unit 3 has a table in which volume threshold values
corresponding to the respective moving speeds are set in advance. In this table, for example, if
the moving speed of the moving object is high, the noise is considered to be large, and even if the
audio signal in the low frequency range is attenuated to a high volume value, the sound does not
become unnaturally audible. A high volume threshold is set. Conversely, if the moving speed is
close to 0 or 0, the noise is considered to be small, and if the audio signal in the low frequency
range is attenuated to a high volume value, it becomes auditory unnatural, so a low volume
threshold is set. . The power saving control unit 3 refers to the table set in this manner, and
acquires a sound volume threshold value corresponding to the moving speed of the moving
object calculated in step ST3.
09-05-2019
6
[0021]
When the power saving control unit 3 determines that the difference between the calculated new
volume threshold and the volume threshold calculated a predetermined time is within the
predetermined range (step ST5; YES), the variation of the volume threshold is small, that is,
movement It is determined that the moving speed of the body is stable, and the calculated new
volume threshold is set as a formal volume threshold (step ST6), and the process proceeds to
step ST7. On the other hand, when it is determined that the difference exceeds the
predetermined range (step ST5; NO), it is determined that the volume threshold fluctuates a lot,
that is, the moving speed of the moving object is not stable, and the volume threshold is not
rewritten. Proceed to the processing of ST7.
[0022]
Further, the power saving control unit 3 refers to the setting information of the volume value
output from the audio unit 23 and determines whether the volume value of the speaker amplifier
7 is currently being adjusted (step ST7). The determination as to whether or not the volume value
of the speaker amplifier 7 is currently being adjusted may be a method of determining whether a
predetermined time (for example, 1 second) has elapsed since the previous adjustment of the
volume value. When adjusting the volume value, a signal indicating the start and end of the
volume value adjustment may be output to the power saving control unit 3. Thereby, for
example, while the user is turning the volume knob of the audio unit 23, transition to the power
saving state or return to the normal state is performed, and abrupt change of the volume value is
prevented. it can.
[0023]
When it is determined that the volume value of the speaker amplifier 7 is not being adjusted
(step ST7; NO), the volume value of the speaker amplifier 7 acquired by the power saving control
unit 3 from the volume adjustment unit 6 is equal to or greater than the set volume threshold. It
is determined whether or not (step ST8). If it is determined that the volume value of the speaker
amplifier 7 is less than the volume threshold (step ST8; NO), the power saving control unit 3
causes the signal control unit 4 to shift control information to shift the speaker 24 selected in
step ST2 to the power saving state. The audio signal to be output to the speaker 24 to be shifted
09-05-2019
7
to the power saving state based on the control information input to the signal control unit 4 is
output to the high pass filter 5 as an attenuated audio signal, and the other audio signals are
normally audio It is output to the volume adjustment unit 6 as a signal (step ST9).
[0024]
The high pass filter 5 attenuates an audio signal having a preset cutoff frequency or less with
respect to the attenuated audio signal input in step ST9, and outputs the attenuated audio signal
to the volume adjuster 6 (step ST10). Further, the power saving control unit 3 controls the
notifying unit 25 to notify that the selected speaker 24 has shifted to the power saving state
(step ST11).
[0025]
On the other hand, when it is determined in step ST7 that the volume value of the speaker
amplifier 7 is being adjusted (step ST7; YES), or it is determined that the volume value of the
speaker 24 is equal to or higher than the volume threshold (step ST8; YES). The power saving
control unit 3 does not shift to the power saving state, but generates control information for
outputting normal audio signals from all the speakers 24 and outputs the control information to
the signal control unit 4, and the signal control unit 4 is input. Based on the control information,
all audio signals are output as normal audio signals to the volume adjuster 6 (step ST12).
[0026]
The volume adjuster 6 attenuates or amplifies the audio signal input in step ST9 and step ST10
or step ST12 based on the volume value set by the audio unit 23 (step ST13).
The speaker amplifier 7 drives the speaker 24 and outputs an audio signal whose volume has
been adjusted in step ST13 (step ST14). Thereafter, the flow returns to the process of step ST1
and repeats the above-described process.
[0027]
As described above, according to the first embodiment, when the volume value set in the volume
adjustment unit 6 is less than the volume threshold, generation of control information for
causing the predetermined speaker 24 to shift to the power saving state is saved. A power
09-05-2019
8
control unit 3 and a signal control unit 4 for outputting an audio signal output from the speaker
24 to be shifted to a power saving state based on control information generated in the power
saving control unit 3 to the high pass filter 5 as an attenuated audio signal; Since the
configuration is made to be provided, power saving of the amplifier can be achieved, and a
natural sound in terms of hearing can be output as a speaker.
[0028]
Further, according to the first embodiment, the moving speed calculation unit 2 that calculates
the moving speed of the moving object, and the volume threshold according to the calculated
moving object speed, calculate the calculated volume threshold and the volume adjusting unit 6
Since the power saving control unit 3 is configured to compare with the volume value set in, the
volume threshold can be set in consideration of the tendency of the running noise to increase
according to the running speed of the moving object. .
[0029]
Further, according to the first embodiment, a seating position detection unit 22 for detecting a
seating seat of the user, and an audio unit 23 for selecting the speaker 24 to be shifted to the
power saving state based on the detection result of the seating seat; A power saving control unit
3 is provided to generate control information to shift the speaker 24 selected by the audio unit
23 to the power saving state when the volume value set in the volume adjustment unit 6 is less
than the volume threshold. Since the system is configured, it is possible to make it difficult for
the user to feel a change in sound even when the predetermined speaker is shifted to the power
saving state.
[0030]
Further, according to the first embodiment, the setting of the volume threshold is performed
when the difference between the new volume threshold calculated by the power saving control
unit 3 and the volume threshold calculated before the predetermined time is within the
predetermined range. As a result, it is possible to prevent frequent fluctuation of the volume
threshold and to prevent unnatural fluctuation of low-frequency sound.
[0031]
Further, according to the first embodiment, when the user is adjusting the volume through the
operation input unit of the audio unit 23, the attenuation of the audio signal by the high pass
filter 5 is not performed. It is possible to prevent transition to the power saving state while the
user is adjusting the volume, and to prevent an abrupt change in the volume value.
09-05-2019
9
[0032]
Second Embodiment
The amplifier according to the second embodiment sets the sound volume threshold according to
the noise level under the use environment of the amplifier 1, and power saving of the amplifier 1
is achieved more efficiently, and a more natural audio output. To achieve.
FIG. 3 is a block diagram showing the configuration of an amplifier and mobile information
device according to a second embodiment of the present invention.
Instead of the moving body information acquiring unit 21 and the moving speed calculating unit
2 having the configuration described with reference to FIG. 1 in the first embodiment, the sound
collecting unit 26, the low pass filter 8, the echo canceller 9 and the noise power measuring unit
10 are used. In place of the seating position detection unit 22, an operation unit 23 a is provided
in the audio unit 23.
In the following, parts identical or corresponding to the constituent elements of the amplifier 1
according to the first embodiment are given the same reference numerals as the reference
numerals used in the first embodiment, and the description will be omitted or simplified.
[0033]
The sound collection unit 26 is configured by, for example, a microphone, and collects the sound
under the use environment of the amplifier 1 including the sound generated through the speaker
24.
In order to suppress the collection of echoes of the sound generated through the speaker 24, the
sound is collected only when the sound generated through the speaker 24 is smaller than a
preset reference value. It is also good. The low-pass filter 8 takes out as a noise signal only a
signal having a frequency equal to or lower than the frequency to be attenuated by the high-pass
filter 5 disposed in the subsequent stage from the sound signal collected by the sound collection
09-05-2019
10
unit 26.
[0034]
The echo canceller 9 removes an audio signal generated from the speaker 24 which is an echo
from the noise signal extracted by the low pass filter 8. An audio signal generated from the
speaker 24 to be an echo to be removed is acquired from the output signal of the speaker
amplifier 7. The noise power measurement unit 10 calculates the power value of the noise signal
from which the echo is removed in the echo canceller 9, and outputs the power value to the
power saving control unit 3.
[0035]
The power saving control unit 3 sets the sound volume threshold of the speaker amplifier 7
according to the power value of the noise signal input from the noise power measurement unit
10, and the current speaker to be acquired from the set sound volume threshold and the sound
volume adjustment unit 6 The volume value of the amplifier 7 is compared. When the current
volume value of the speaker amplifier 7 is equal to or higher than the volume threshold, the
control information instructing the transition of the speaker 24 selected to be able to be set to
the power saving state in the audio unit 23 to the power saving state is It is generated and output
to the signal control unit 4.
[0036]
The operation unit 23a is configured by an operation panel, an operation button, and the like
that allow the user to perform an operation input, and sets the speaker 24 to be shifted to the
power saving state. For example, the speaker 24 located near the seat where the user is not
seated is set to shift to the power saving state, the woofer speaker for reproducing mainly the
audio signal in the low frequency range, or the subwoofer speaker is power saving state The user
can arbitrarily select the speaker 24 to be shifted to the power saving state, such as setting to
shift to the lower power state. The audio unit 23 outputs, to the power saving control unit 3, the
speaker information to be shifted to the power saving state selected through the operation unit
23a.
09-05-2019
11
[0037]
Next, the operation will be described. FIG. 4 is a flowchart showing the flow of the operation of
the mobile information device including the amplifier of the second embodiment. In the
following, the same steps as those of the amplifier 1 according to the first embodiment are
denoted by the same reference numerals as those used in FIG. 2, and the description will be
omitted or simplified. When the user sets the speaker 24 via the operation unit 23a (step ST21),
the audio unit 23 selects the speaker 24 to be shifted to the power saving state based on the
setting of step ST21 (step ST22).
[0038]
The sound collecting unit 26 collects the sound under the amplifier usage environment (step
ST23). Only the noise signal is acquired from the sound collected in step ST23 through the low
pass filter 8 and the echo canceller 9 (step ST24). Specifically, the collected sound is limited by
the low pass filter 8 to a frequency signal of a band to be attenuated by the high pass filter 5 in
the subsequent stage. Further, the echo canceler 9 is passed and the echo of the audio signal
emitted by the speaker 24 is removed. By passing the low pass filter 8 and the echo canceller 9
in this manner, only the noise signal is acquired.
[0039]
The noise power measurement unit 10 measures the power value of the noise signal acquired in
step ST24 (step ST25). The power saving control unit 3 calculates a new volume threshold based
on the power value of the noise signal measured in step ST 25 (step ST 26), and the new volume
threshold calculated in step ST 26 is a predetermined time ago (for example, 1) It is determined
whether or not the difference from the sound volume threshold value calculated in minutes) is
within a predetermined range (step ST5).
[0040]
In step ST26, it is assumed that the power saving control unit 3 holds a table in which a volume
threshold corresponding to the power value of each noise signal is set in advance. In this table,
for example, when the power value of the noise signal is high, the noise is considered to be high,
09-05-2019
12
and even if the audio signal in the low frequency range is attenuated to a high volume value, it
does not become an auditory unnatural sound. A high volume threshold is set. Conversely, when
the power value of the noise signal is small, the noise is considered to be small, and if the audio
signal in the low frequency range is attenuated to a high volume value, the low sound level
threshold is set because it becomes unnaturally audible. The power saving control unit 3 refers to
the table set in this way, and acquires a volume threshold corresponding to the power value of
the noise signal measured in step ST25.
[0041]
If the power saving control unit 3 determines that the difference between the calculated new
volume threshold and the volume threshold calculated a predetermined time ago is within the
predetermined range (step ST5; YES), the variation of the volume threshold is small, ie, It is
determined that the power value of the noise signal (moving speed of the moving object) is
stable, and the calculated new volume threshold is set as a formal volume threshold (step ST6),
and the process proceeds to step ST7. On the other hand, when it is determined that the
difference exceeds the predetermined range (step ST5; NO), it is determined that the volume
threshold fluctuates a lot, that is, the power value of the noise signal (moving speed of moving
object) is not stable. The process proceeds to step ST7 without rewriting. Thereafter, the flow
performs the same processing as steps ST7 to ST14 shown in the first embodiment.
[0042]
As described above, according to the second embodiment, the noise power measurement unit 10
for measuring the power value of the noise signal under the use environment of the amplifier 1
and the volume threshold corresponding to the power value of the noise signal are set. Since the
power saving control unit 3 configured to set the speaker 24 to shift to the power saving state
using the volume threshold is configured, it is possible to set the speaker using noise actually
measured. It is possible to realize power saving that enables efficient and more natural audio
output.
[0043]
Further, according to the second embodiment, the low-pass filter 8 for limiting the sound signal
collected by the sound collection unit 26 to the frequency band attenuated by the high-pass filter
5 at the transition to the power saving state is provided. Since the volume threshold
corresponding to the power value of the noise signal is set, it can be accurately determined
whether the audio band attenuated by the high pass filter 5 is actually buried in the noise.
09-05-2019
13
[0044]
Further, according to the second embodiment, the user can select the speaker 24 to be shifted to
the power saving state via the operation unit 23a, so that the speaker can be controlled in
accordance with the user's preference.
[0045]
Third Embodiment
The amplifier according to the third embodiment sets the sound volume threshold according to
the noise level of the amplifier 1 in the same manner as the second embodiment, and shows
another example of the configuration.
FIG. 5 is a block diagram showing the configuration of an amplifier and mobile information
device according to a second embodiment of the present invention.
A frequency band converter 11 and a noise band detector 12 are provided in place of the low
pass filter 8 having the configuration described with reference to FIG. 3 in the second
embodiment. The audio unit 23 further includes a speaker setting unit 23 b that automatically
sets the speaker 24 to be shifted to the power saving state. In the following, parts identical or
corresponding to the constituent elements of the amplifier 1 according to the first embodiment
and the second embodiment will be described with the same reference numerals as those used in
the first embodiment and the second embodiment. Omit or simplify.
[0046]
The sound collection unit 26 is configured by, for example, a microphone, and collects the sound
under the use environment of the amplifier 1 including the sound generated through the speaker
24. In order to suppress the collection of echoes of the sound generated through the speaker 24,
the sound is collected only when the sound generated through the speaker 24 is smaller than a
preset reference value. It is also good. The echo canceller 9 removes an audio signal generated
from the speaker 24 which is an echo from the sound collected by the sound collection unit 26
and outputs the signal to the noise power measurement unit 10 and the frequency band
09-05-2019
14
conversion unit 11. An audio signal generated from the speaker 24 to be an echo to be removed
is acquired from the output signal of the speaker amplifier 7.
[0047]
The noise power measurement unit 10 calculates the power value of the noise signal from which
the echo is removed in the echo canceller 9, and outputs the power value to the power saving
control unit 3. The frequency band conversion unit 11 Fourier-transforms the noise signal from
which the echo is removed in the echo canceller 9 to calculate a noise spectrum. The noise band
detection unit 12 detects a band of noise from the noise spectrum calculated by the frequency
band conversion unit 11, and calculates the maximum frequency in the detected noise band.
Furthermore, a filter coefficient with the calculated maximum frequency as a cutoff frequency is
calculated, and is set in the high pass filter 5. The high pass filter 5 sets a cutoff frequency from
the filter coefficient set by the noise band detection unit 12 and attenuates an audio signal in the
same band as the noise signal.
[0048]
The power saving control unit 3 sets the sound volume threshold of the speaker amplifier 7
according to the power value of the noise signal input from the noise power measurement unit
10, and the current speaker to be acquired from the set sound volume threshold and the sound
volume adjustment unit 6 The volume value of the amplifier 7 is compared. When the current
volume value of the speaker amplifier 7 is less than the volume threshold, the control
information instructing the transition of the speaker 24 selected to be able to be set to the power
saving state in the audio unit 23 to the power saving state is It is generated and output to the
signal control unit 4. The speaker setting unit 23b of the audio unit 23 has setting information of
the speaker 24 (for example, a woofer speaker for reproducing mainly an audio signal in a low
frequency range or a subwoofer speaker) to be shifted to the power saving state in advance.
[0049]
Next, the operation will be described. FIG. 6 is a flowchart showing the flow of the operation of
the mobile information device including the amplifier 1 of the third embodiment. In the
following, the same steps as those of the mobile information device including the amplifier 1
according to the first embodiment and the second embodiment are indicated by the same
09-05-2019
15
reference numerals as those used in FIG. 2 or FIG. Simplify. When the speaker setting unit 23b of
the audio unit 23 outputs the speaker 24 information to be shifted to the power saving state
(step ST31), the sound collecting unit 26 collects the sound under the use environment of the
amplifier 1 (step ST32) . The noise canceller 9 removes the echo of the audio signal emitted by
the speaker 24 from the sound collected in step ST32, whereby the noise power measurement
unit 10 and the frequency band conversion unit 11 acquire only the noise signal (step ST33). ).
[0050]
The noise power measurement unit 10 measures the power value of the noise signal acquired in
step ST33 (step ST25). The power saving control unit 3 calculates a new volume threshold based
on the power value of the noise signal measured in step ST 25 (step ST 26), and the new volume
threshold calculated in step ST 26 is a predetermined time ago (for example, 1) It is determined
whether or not the difference from the sound volume threshold value calculated in minutes) is
within a predetermined range (step ST5). In step ST26, as in the second embodiment, the power
saving control unit 3 has a table in which volume threshold values corresponding to the power
values of the noise signals are set in advance.
[0051]
When the power saving control unit 3 determines that the difference between the calculated new
volume threshold and the volume threshold calculated a predetermined time is within the
predetermined range (step ST5; YES), the variation of the volume threshold is small, that is, noise
It is determined that the power value of the signal (the moving speed of the moving object) is
stable, and the calculated new volume threshold is set as a formal volume threshold (step ST6),
and the process proceeds to step ST34. On the other hand, when it is determined that the
difference in volume threshold exceeds the predetermined range (step ST5; NO), it is determined
that the variation in volume threshold is large, that is, the power value of the noise signal
(moving speed of moving object) is not stable. Then, the process proceeds to step ST34 without
rewriting the volume threshold.
[0052]
The frequency band conversion unit 11 Fourier transforms the noise signal acquired in step
ST33 to calculate a noise spectrum, and calculates the maximum frequency in the noise band
09-05-2019
16
detected from the noise spectrum calculated by the noise band detection unit 12 (step ST34) ).
Furthermore, the noise band detection unit 12 determines whether the difference between the
maximum frequency in the new noise band calculated in step ST34 and the maximum frequency
calculated a predetermined time ago (for example, one minute ago) is within a predetermined
range. (Step ST35).
[0053]
If the noise band detection unit 12 determines that the difference between the calculated new
maximum frequency and the calculated maximum frequency within the predetermined time is
within the predetermined range (step ST35; YES), it is determined that the noise fluctuation is
small. A filter coefficient with the calculated new maximum frequency as a cutoff frequency is
calculated and set in the high pass filter 5 (step ST36), and the process proceeds to step ST7. On
the other hand, if it is determined that the difference in maximum frequency exceeds the
predetermined range (step ST35; NO), the process proceeds to step ST7 without rewriting the
filter coefficient of the high pass filter 5. Thereafter, the flow performs the same processing as
steps ST7 to ST14 shown in the first embodiment, returns to the processing of step ST32, and
repeats the above-mentioned processing.
[0054]
As described above, according to the third embodiment, the frequency band conversion unit 11
calculates the noise spectrum by performing Fourier transform on the noise signal from which
the echo is removed in the echo canceller 9, and the maximum frequency of the noise band from
the noise spectrum. Since the noise band detection unit 12 calculates the filter coefficient with
the maximum frequency as the cutoff frequency and sets it as the high pass filter 5, the
frequency of the noise signal is shifted when shifting to the power saving state. A high pass filter
can be set to attenuate only the audio signal in the band. Furthermore, the audio signal can be
attenuated according to the situation of noise, and power saving of the amplifier can be
performed efficiently.
[0055]
In the first to third embodiments described above, the selection of the speaker 24 to be shifted to
the power saving state is automatically set by the configuration using the seating position
09-05-2019
17
detection unit 22, the configuration using the operation unit 23a, and the speaker setting unit
23b. Although the respective configurations are shown, they can be appropriately configured
according to the application. Although the seating position detection unit 22 has a configuration
in which the audio unit 23 has an external configuration, the seating position detection unit 22
may be incorporated in the audio unit 23.
[0056]
In the first to third embodiments described above, the notification unit 25 has the external
configuration of the amplifier 1 and the audio unit 23. However, the notification unit 25 may be
incorporated in the audio unit 23.
[0057]
In the scope of the invention, the present invention allows free combination of each embodiment,
or modification of any component of each embodiment, or omission of any component in each
embodiment. .
[0058]
REFERENCE SIGNS LIST 1 amplifier 2 moving speed calculation unit 3 power saving control unit
4 signal control unit 5 high pass filter 6 volume adjustment unit 7 speaker amplifier 8 low pass
filter 9 echo canceler 10 noise power measurement unit 11 frequency band Conversion unit, 12
noise band detection unit, 21 mobile information acquisition unit, 22 seating position detection
unit, 23 audio unit, 23a operation unit, 23b speaker setting unit, 24 speaker, 25 notification unit,
26 sound collection unit.
09-05-2019
18

Download Report