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JP2015015509

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DESCRIPTION JP2015015509
PROBLEM TO BE SOLVED: To provide an audio signal amplifier which is less likely to be
unpleasant for a user by suppressing generation of an operation noise of an output switch circuit.
SOLUTION: An audio signal amplifier outputs an audio signal to an output terminal from a first
state in which a control unit amplifies an operation of the audio signal amplifier and outputs one
of the input audio signals to a corresponding output terminal. When switching to the second
state, the switch of the output switch circuit unit corresponding to the output terminal not
outputting the audio signal in the second state is set to a volume control instruction larger than a
predetermined threshold value in the instruction input unit. If it is set, the cutting operation is
performed, and if it is set smaller than the threshold value, control is performed to maintain the
energization operation. [Selected figure] Figure 1
Voice signal amplifier
[0001]
The present invention relates to an audio signal amplifier that amplifies an audio signal and
outputs the amplified audio signal to an electroacoustic transducer, and more particularly, an
audio signal amplifier including an output switch circuit that switches whether to output an
audio signal to an output terminal connected to a speaker. About.
[0002]
In an audio apparatus for reproducing sound, an audio signal amplifier such as an amplifier
circuit that amplifies an electrically recorded audio signal and supplies the amplified signal to an
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electroacoustic transducer such as a speaker is used.
The audio signal amplifier includes a volume adjustment circuit unit including a volume circuit
inside, an amplifier circuit unit corresponding to a power amplification stage, and an output
switch circuit unit. If the audio signal amplifier and the electroacoustic transducer are provided
separately, the electroacoustic transducer is used by being connected to the output terminal of
the audio signal amplifier. Further, even when the audio signal amplifier and the electroacoustic
transducer are integrally formed, the electroacoustic transducer is connected to the output
terminal of the audio signal amplifier in its interior.
[0003]
The output switch circuit unit is provided to switch whether or not to output an output signal
from the amplification circuit unit to an output terminal to which the electroacoustic transducer
is connected. Specifically, since the output power from the amplification circuit section is
relatively large in the output switch circuit section, a relay element that performs a cutting
operation / energization operation by moving a contact with magnetism that generates a current
through the coil is generated. Used. In recent audio devices, in addition to a two-channel
amplifier compatible with stereo sound, an AV amplifier etc. compatible with a plurality of multichannel audio such as 9.2 channels, for example, are present. The quantity of has also increased.
[0004]
The relay element of the output switch circuit section is switched depending on whether or not
the audio signal is output to the output terminal, so that the disconnection operation /
energization operation is performed quite frequently during the operation of the audio
apparatus. For example, in an AV amplifier compatible with multi-channel audio, in addition to
performing disconnection operation / energization operation to protect the speaker during
power on / off operation, the audio signal format of the input audio signal is switched. In
response to the change of the surround setting by the user operation or user operation, an
operation of disconnecting a part of relay elements of the output switch circuit unit so as to
suppress the output to the unused speaker corresponding to the channel where the audio signal
is not present May be This is to prevent unwanted crosstalk noise from being reproduced from a
speaker that should not be used even if unwanted crosstalk noise occurs in which an audio signal
leaks from a channel where an audio signal is present to a non-existent channel. It is.
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[0005]
In the output switch circuit unit configured to use the relay element, an operation noise is
generated that mechanically moves the contacts in accordance with the disconnection operation
/ energization operation. As described above, since the relay element of the output switch circuit
section performs the disconnection operation / energization operation quite frequently during
the operation of the audio apparatus, as a result, the output switch circuit section which occurs
frequently for some users. There is a problem that the operation sound of may feel
uncomfortable. In particular, in a quiet environment where the ambient noise is small, when the
plurality of relay elements perform the disconnection operation / energization operation, the
operation noise of the output switch circuit unit may be annoying.
[0006]
Conventionally, to provide a display device with a timer function capable of performing control
so as to suppress noise (rotary noise of a fan, relay sound when power is off, etc.) output from
the display device itself when setting a timer. After setting the timer, according to the timer time,
it is set so that the noise emitted by the display device itself does not disturb the user, and
various settings such as the screen of the display device, voice and fan are automatically changed
over time There is a display device that can be set (Patent Document 1). In Patent Document 1,
after the standby state continues for a certain period of time, the power supply relay for turning
on / off the AC power of the display device is disconnected. However, Patent Document 1 is
concerned that a relay sound is generated when using a display device or the like, so by setting a
certain time for continuing the standby state to be considerably long, the user does not mind The
relay is only supposed to be disconnected.
[0007]
JP, 2007-135018, A
[0008]
The present invention has been made to solve the above-mentioned problems of the prior art,
and its object is to suppress the generation of the operation noise of the output switch circuit,
and to reduce the amount of discomfort for the user. To provide.
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[0009]
The audio signal amplifier according to the present invention changes the volume of a plurality
of input audio signals and outputs the volume control circuit unit, the amplification circuit unit
amplifying each output signal from the volume adjustment circuit unit, and the amplification
circuit unit Of the output switch circuit unit for switching whether or not each output signal of
each is output to the output terminal to which each of the plurality of electroacoustic transducers
is connected, the operation of the volume control circuit unit, the amplifier circuit unit, and the
output switch circuit unit An audio signal amplifier comprising: a control unit for controlling the
control unit; and an instruction input unit connected to the control unit to which a user operation
including a volume control instruction to the volume adjustment circuit unit is input, wherein the
control unit is an audio signal When switching the operation of the amplifier from the first state
in which any one input audio signal is amplified and output to the corresponding output terminal
to the second state in which the audio signal is not output to the output terminal, the output
terminal If the volume control command at the command input unit is set to a value larger than a
predetermined threshold value, the output switch circuit unit corresponding to is cut off. If it is
set smaller than the threshold value, an energization operation is performed. Control to maintain.
[0010]
Preferably, in the audio signal amplifier according to the present invention, the first state
includes a case where all of a plurality of input audio signals are amplified and output to all
output terminals, and a second state is for a plurality of input audio signals. There is a case
where at least one is amplified and output to the corresponding output terminal, and an audio
signal is not output to at least one output terminal.
[0011]
Preferably, in the audio signal amplifier according to the present invention, the switch of the
output switch circuit unit includes a relay element that moves a contact by magnetism that
generates a current in a coil and generates a disconnection operation / energization operation.
[0012]
Preferably, in the audio signal amplifier according to the present invention, the control unit sets
and stores the threshold value to a predetermined value based on a user operation from the
instruction input unit.
[0013]
Also preferably, in the audio signal amplifier according to the present invention, the control unit
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selects the first state or the second state based on an audio signal format of an input audio signal
or surround setting by user operation from the instruction input unit. And switch.
[0014]
Hereinafter, the operation of the present invention will be described.
[0015]
The audio signal amplifier according to the present invention changes the volume of a plurality
of input audio signals and outputs the volume control circuit unit, the amplification circuit unit
amplifying each output signal from the volume adjustment circuit unit, and the amplification
circuit unit Of the output switch circuit unit for switching whether or not each output signal of
each is output to the output terminal to which each of the plurality of electroacoustic transducers
is connected, the operation of the volume control circuit unit, the amplifier circuit unit, and the
output switch circuit unit And an instruction input unit which is connected to the control unit
and in which a user operation including a volume control instruction to the volume adjustment
circuit unit is input.
The control unit switches the operation of the audio signal amplifier from the first state in which
any one input audio signal is amplified and output to the corresponding output terminal to the
second state in which the audio signal is not output to the output terminal. The output switch
circuit unit corresponding to the output terminal not outputting the audio signal in the second
state is disconnected if the volume control instruction at the instruction input unit is set larger
than the predetermined threshold, and is less than the threshold If it is set to a small value,
control is performed to maintain the energization operation.
[0016]
Therefore, even if the operation signal of the output switch circuit unit is generated when
switching from the first state to the second state, the audio signal amplifier disconnects the
output switch circuit unit in the case of reproducing sound with a relatively large volume. It is
possible to operate, and on the other hand, when the voice is reproduced at a relatively small
volume, the energizing operation in the output switch circuit unit can be maintained so that the
operation noise is not generated.
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In the case of reproducing the sound at a relatively large volume, the operation sound of the
output switch circuit unit is easily masked by the reproduced sound, so the user hardly feels the
operation sound of the output switch circuit uncomfortable.
In addition, in the case of reproducing the sound at a relatively small volume, the energizing
operation in the output switch circuit unit corresponding to the output terminal which does not
output the audio signal is maintained, so that no operation noise is generated.
As a result, it is possible to make the user virtually not feel the operation noise of the output
switch circuit.
[0017]
The first state means a state in which the input audio signal is intended to be amplified and
output to the corresponding output terminal, and the second state is an audio signal at the
output terminal regardless of the operation of the output switch circuit section. It means a state
intended not to output.
In addition, the first state described above includes the case where all the plurality of input audio
signals are amplified and output to all the output terminals, and the second state is configured to
amplify at least one of the plurality of input audio signals It may include the case of outputting to
the corresponding output terminal and not outputting the audio signal to at least one output
terminal.
Specifically, even if the state is changed so as not to output an audio signal to a certain output
terminal, all the switches of the output switch circuit unit corresponding to all the output
terminals are maintained to be energized. May be
When the input audio signal consists of a plurality of channel components, one audio channel
may be amplified and output to the corresponding output terminal, and an audio signal may not
be output to the other output terminal. It is preferable to suppress the occurrence.
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In the case of reproducing the sound at a relatively large volume, the crosstalk noise tends to be
relatively large, while in the case of reproducing the sound at a relatively small volume, the
crosstalk noise is relatively small. The audio signal amplifier according to the present invention
disconnects the output switch circuit to prevent reproduction of a large crosstalk noise when
reproducing audio at a relatively large volume, while reducing a relatively small volume. In the
case of reproducing the sound at this time, since the crosstalk noise is also small, the
energization operation in the output switch circuit unit corresponding to the output terminal not
outputting the audio signal is maintained. As a result, it is possible to substantially prevent
unwanted crosstalk noise from being reproduced from an unused speaker, and to make the user
not feel the operation noise of the output switch circuit uncomfortable. it can.
[0018]
Further, in the audio signal amplifier, the switch of the output switch circuit unit may include a
relay element that moves a contact by magnetism that generates current by flowing a coil and
performs a cutting operation / energization operation. When the switch of the output switch
circuit unit is a relay element, the operation noise tends to be annoying in a quiet environment
where ambient noise is small. Therefore, when the voice is reproduced at a relatively small
volume, no operation noise is generated by maintaining the energization operation in the output
switch circuit portion corresponding to the output terminal which does not output the voice
signal, and as a result, the user Therefore, it is possible to make the operation noise of the output
switch circuit not to feel substantially unpleasant.
[0019]
Further, the audio signal amplifier may be configured such that the control unit sets and stores
the threshold value related to the volume control instruction to a predetermined value based on
the user operation from the instruction input unit. Whether or not the operation noise of the
output switch circuit is offensive depends on the sense of each user or the difference in ambient
noise, so it is switched whether to cut off the output switch circuit unit or maintain the
energization operation. The volume control instruction to the volume adjustment circuit can be
optimally adjusted for each user.
[0020]
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In the audio signal amplifier, the control unit selects the first state or the second state based on
the audio signal format of the input audio signal or the surround setting by the user operation
from the instruction input unit. It may be switched. In the output switch circuit unit, whether to
amplify the audio signal and output it to the corresponding output terminal is determined based
on the audio signal format of the input audio signal or the surround setting by the user operation
from the instruction input unit Therefore, in the present invention, when the voice is reproduced
at a relatively small volume, the generation of the operation noise of the output switch circuit can
be suppressed by maintaining the energization operation in the output switch circuit section. In
particular, depending on the content to be reproduced, the audio signal format of the input audio
signal may change frequently. The audio signal amplifier may also be user-set to automatically
switch the surround settings according to the audio signal format. Therefore, when the voice is
reproduced at a relatively small volume, the number of operations of the output switch circuit is
substantially reduced, so that when the switch of the output switch circuit portion includes a
relay element, the relay element Can reduce the risk of failure.
[0021]
The audio signal amplifier according to the present invention can suppress the generation of the
operation noise of the output switch circuit to reduce the user's discomfort. Moreover, it is
substantially prevented that unwanted crosstalk noise is reproduced from the speaker which
should not be used, and when the switch of an output switch circuit part contains a relay element
etc., the failure risk of a relay element is reduced. be able to.
[0022]
It is a figure explaining the audio | voice signal amplifier by preferable embodiment of this
invention. (Example 1) It is a figure explaining the threshold-value regarding volume control
instruction in CPU of an audio signal amplifier. (Example 1) It is a flowchart explaining operation
control in CPU of an audio signal amplifier. Example 1
[0023]
The audio signal amplifier according to the preferred embodiments of the present invention will
be described below, but the present invention is not limited to these embodiments.
[0024]
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FIG. 1 is a block diagram for explaining an audio signal amplifier 1 according to a preferred
embodiment of the present invention.
Specifically, the audio signal amplifier 1 is an AV amplifier connected to a content reproduction
device (not shown), a display device (not shown), and a speaker system (not shown) to reproduce
video and audio, The audio signal amplifier 1 constitutes a content reproduction system (not
shown) corresponding to stereo audio signals and multi-channel audio signals. In addition,
illustration and description are abbreviate | omitted for the one part structure unnecessary for
description, an internal structure, etc. FIG.
[0025]
The audio signal amplifier 1 decodes multi-channel audio data input from the content
reproduction apparatus (not shown) to the terminal adata, amplifies it for each channel, and
connects to the speaker terminal group TSP (not shown) Output to speakers and play multichannel audio to viewers (users). The audio signal amplifier 1 decodes multi-channel audio data
into 7.1-channel surround audio data by a decoding circuit 11 configured inside a DSP (Digital
Signal Processor) 10. The 7.1-channel audio data includes all bands of front left data L, front
right data R, front center data C, surround left data SL, surround right data SR, surround back left
data SBL, and surround back right data SBR. A total of seven channels including components and
band-limited bass data LFE. The 7.1 channel audio data is output to a DAC (Digital Analog
Converter) 2 via a surround mode setting circuit 12 configured inside the DSP 10, and converted
to a 7.1 channel analog audio signal.
[0026]
Each analog audio signal output from the DAC 2 is volume-controlled through a master volume
circuit 8 which is a volume adjustment circuit. The volume of the master volume circuit 8 is
controlled by the CPU 5 described later. A total of seven channels of the 7.1-channel analog
audio signal including components of the entire band are amplified by the amplifier 3 for
amplifying each channel audio, and the output switch circuit 4 configured of a plurality of switch
relays , Speaker terminal group TSP. Also, the band-limited bass signal LFE is output from the
terminal lfe and input to the amplifier built-in subwoofer Sub (not shown).
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[0027]
The output switch circuit 4 of the audio signal amplifier 1 includes switch relays corresponding
to the speaker terminals (l, c, r, sl, sr, sbl, sbr) of the speaker terminal group TSP. The switch
relay is a relay element that moves a contact by magnetism that generates a current through a
coil and moves the contact / disconnection operation, and the operation is controlled by a CPU 5
described later. The output switch circuit 4 responds to the switching of the audio signal format
of the input audio signal as well as performing the disconnection operation / energization
operation so as to protect the speaker during the power on / off operation of the audio signal
amplifier 1 Or, in response to the change of the surround setting by user operation, the output to
the unused speaker corresponding to the channel where the audio signal is not present (that is,
the speaker corresponding to the channel for which the audio output is not intended) is
suppressed And disconnect some relay elements. In addition, the switch relay generates an
operation noise associated with the disconnection operation / energization operation. Therefore,
in a quiet environment with little ambient noise, the user may hear the operation sound of the
output switch circuit 4 of the audio signal amplifier 1.
[0028]
Further, the audio signal amplifier 1 includes a CPU (central processing unit) 5 for controlling the
whole, an operation circuit 6 including a volume switch, and a display circuit 7 including a liquid
crystal display panel and an LED. Other circuit configurations are omitted in FIG. The operation
circuit 6 and the display circuit 7 of the multi-channel audio amplification device 1 allow the user
to adjust the volume setting value related to the volume control instruction, and adjust the
magnitude of the reproduction volume. Further, the CPU 5 can set and store a threshold value
related to a volume control instruction described later to a predetermined value based on a user
operation from the operation circuit 6.
[0029]
The 7.1 channel surround audio data is converted to a 7.1 channel analog audio signal through
the surround mode setting circuit 12 and the DAC 2. In this embodiment, the speaker system (not
shown) corresponds to the front left speaker corresponding to the front left audio signal (L), the
front right speaker corresponding to the front right audio signal (R), and the front center audio
signal (C). Front center speaker, surround left speaker corresponding to surround left audio
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signal (SL), surround right speaker corresponding to surround right audio signal (SR), surround
rear left speaker corresponding to surround back left audio signal (SBL), surround It is a sevenchannel system consisting of a surround back right speaker corresponding to a rear right audio
signal (SBR) and a subwoofer corresponding to a bass signal (LFE).
[0030]
The speaker used to reproduce the sound in the speaker system is selected based on the sound
signal format of the 7.1 channel surround sound data or the surround setting in the surround
mode setting circuit 12. For example, when the input audio data is stereo audio and the surround
setting is "stereo mode", the front left speaker and the front right speaker reproduce audio, and
the other speakers do not reproduce audio. Also, if the input audio data is stereo audio and the
surround setting is "all channel stereo mode", or if the input audio data is 7 channel audio, the
surround setting is "surround mode (or all channel stereo mode)" If so, all seven speakers play
the sound. Therefore, in the audio signal amplifier 1, the CPU 5 appropriately controls the output
switch circuit 4 to control whether the speaker connected to the corresponding amplifier circuit
3 is connected or disconnected.
[0031]
FIG. 2 is a diagram for explaining the threshold value related to the volume control instruction in
the CPU 5 of the audio signal amplifier 1. Horizontal axis Vol. Is a volume control in the master
volume circuit 8 and shows an adjustable range from the minimum volume level-infinity dB to
the maximum 0 dB. In reproduction of movie content or music content, the master volume is
often subjected to volume control in the range of about -60 to -30 dB. The CPU 5 stores a
threshold set in advance or set by the user (for example, a value A corresponding to a master
volume of −50 dB in the range of 0 to 100), and the master volume is equal to or higher than
the threshold. It is determined whether the operation of disconnecting the relay of the circuit 4
or the master volume is less than the threshold value and "does not disconnect the relay of the
output switch circuit 4 (maintain the energizing operation)".
[0032]
Further, FIG. 3 is a flow chart for explaining the operation control of the CPU 5 of the audio
signal amplifier 1. Here, in the CPU 5, the surround setting in the surround mode setting circuit
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12 is “all channel stereo mode”, and corresponds to the audio signals (L, R, C, SL, SR, SBL, SBR)
of the output switch circuit 4. The case where all the relays are controlled to "ON (energization)"
(S101) is illustrated. The processing in the case where the CPU 5 receives a request to switch the
surround setting to the "stereo mode" by changing the multi-channel audio data via the operation
circuit 6 of the audio signal amplifier 1 (S102) will be described.
[0033]
The CPU 5 determines whether or not the current master volume is equal to or greater than the
threshold A in volume control in the master volume circuit 8 (S103). If it is the threshold A or
more (S103: Yes), the surround setting is switched to the "stereo mode", and the relay
corresponding to the audio signal (L, R) of the output switch circuit 4 is kept "ON (energized)"
The relay corresponding to the audio signal (C, SL, SR, SBL, SBR) is controlled to "OFF
(disconnection)" (S104). In this case, in the relay corresponding to the audio signal (C, SL, SR,
SBL, SBR) controlled to "OFF (disconnection)", an operation sound of the relay is generated.
However, since the master volume is equal to or higher than the threshold A, the voice is
reproduced at a relatively large volume. Therefore, the operation sound of the output switch
circuit unit is masked by the reproduced voice, and as a result, the user The operating noise of
the output switch circuit 4 is less likely to be uncomfortable. Also, in this case, even if unwanted
crosstalk noise occurs in which the audio signal leaks from the channel (L, R) in which the audio
signal is present to the non-existent channel, the corresponding relay is controlled to "OFF
(disconnection)" Because of this, undesirable crosstalk noise is not reproduced from the speakers
corresponding to the audio signals (C, SL, SR, SBL, SBR).
[0034]
On the other hand, when the CPU 5 determines that the current master volume is less than the
threshold A (S103: No), the surround setting is switched to the "stereo mode" and the audio
signal of the output switch circuit 4 (C, The relay corresponding to SL, SR, SBL, SBR) is controlled
to be kept "ON (energized)" (S105). In this case, since all the relays are not controlled to "OFF
(disconnection)", the operation noise of the relays is not generated. Here, since the master
volume is less than the threshold A, the user does not feel uncomfortable the operation sound of
the output switch circuit 4 even if the voice is reproduced at a relatively small volume. Also, in
this case, even if unwanted crosstalk noise occurs in which the audio signal leaks from the
channel (L, R) in which the audio signal is present to the non-existent channel, the sound is
reproduced at a relatively small volume. Thus, crosstalk noise is reduced, and undesired crosstalk
noise can be prevented from being reproduced from each speaker substantially corresponding to
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the audio signal (C, SL, SR, SBL, SBR).
[0035]
Next, the case where the master volume value is changed from the state of (S104) to a value less
than the threshold A (S106) will be described. When the CPU 5 determines that the current
master volume is less than the threshold A in the volume control in the master volume circuit 8,
the relay corresponding to the audio signal (L, R) of the output switch circuit 4 is turned on
(energized) The relay corresponding to the audio signal (C, SL, SR, SBL, SBR) is controlled to be
maintained at "OFF (disconnection)" (S107). In this case, since all the relays do not operate, no
operation noise of the relays is generated. Here, since the master volume is less than the
threshold A, the user does not feel uncomfortable the operation sound of the output switch
circuit 4 even if the voice is reproduced at a relatively small volume. Also, in this case, even if
unwanted crosstalk noise occurs in which the audio signal leaks from the channel (L, R) in which
the audio signal is present to the non-existent channel, the corresponding relay is controlled to
"OFF (disconnection)" Because of this, undesirable crosstalk noise is not reproduced from the
speakers corresponding to the audio signals (C, SL, SR, SBL, SBR).
[0036]
Next, the case where the master volume value is changed to the threshold A or more from the
state of (S105) (S108) will be described. When the CPU 5 determines that the current master
volume is the threshold A or more in the volume control in the master volume circuit 8, the relay
corresponding to the audio signal (L, R) of the output switch circuit 4 is turned on (energized)
The relay corresponding to the audio signal (C, SL, SR, SBL, SBR) is controlled to be "OFF
(disconnection)" (S109). In this case, as in the state of (S104), in the relay corresponding to the
audio signal (C, SL, SR, SBL, SBR) controlled to "OFF (disconnection)", an operation sound of the
relay is generated. However, since the master volume is equal to or higher than the threshold A,
if the voice is reproduced at a relatively large volume, the operation sound of the output switch
circuit unit 4 is masked by the reproduced voice, and as a result, the user The operation noise of
the circuit 4 is less unpleasant. Also, in this case, even if unwanted crosstalk noise occurs in
which the audio signal leaks from the channel (L, R) in which the audio signal is present to the
non-existent channel, the corresponding relay is controlled to "OFF (disconnection)" Because of
this, undesirable crosstalk noise is not reproduced from the speakers corresponding to the audio
signals (C, SL, SR, SBL, SBR).
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[0037]
As described in the above embodiment, the audio signal amplifier 1 does not output an audio
signal to its output terminal from the first state in which any input audio signal is amplified and
output to the corresponding output terminal. Even when the operation sound of the output
switch circuit unit 4 is generated at the time of switching to the switch, the output switch circuit
unit 4 can be disconnected in the case of reproducing the sound with a relatively large sound
volume, while relatively When the voice is reproduced at a small volume, the energizing
operation in the output switch circuit unit 4 can be maintained so that the operation noise is not
generated. As a result, when the user reproduces the sound at a relatively large volume, the
operation sound of the output switch circuit unit 4 is easily masked by the reproduced sound,
and the user feels the operation sound of the output switch circuit 4 uncomfortable. There is an
advantage that it becomes less. In addition, unwanted crosstalk noise can be substantially
prevented from being reproduced from an unused speaker.
[0038]
Further, the switch of the output switch circuit unit 4 in the above embodiment is a relay element
that moves a contact by magnetism generated by passing a current through a coil to perform a
cutting operation / energization operation, but the switch of the output switch circuit unit 4 is
Other than the relay element, it may be a switch element that generates an operation noise in a
quiet environment with little ambient noise. In the case of reproducing the sound at a relatively
small volume, by maintaining the energizing operation in the output switch circuit unit 4
corresponding to the output terminal which does not output the audio signal, no operation noise
is generated, and as a result, for the user The operation noise of the output switch circuit 4 can
be substantially prevented from feeling unpleasant.
[0039]
Further, the audio signal amplifier 1 may set the threshold A related to the volume control
instruction to a predetermined value based on the user operation from the operation circuit 6
and store it. For example, even if the threshold A is set relatively small, the operation sound of
the output switch circuit 4 has an advantage of increasing the chances of being not offensive to
the user as compared with the case where the threshold A is not set. When the value of the
current master volume used by the user becomes equal to or less than the threshold A, the
operation of “disconnecting the relay of the output switch circuit 4 is not performed
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(maintaining the energization operation)” is performed, and the operation sound of the output
switch circuit 4 The number of occurrences of Further, since the number of operations of the
output switch circuit 4 is substantially reduced, depending on the content to be reproduced, if
the audio signal format of the input audio data changes frequently, or if the surround setting is
set corresponding to the audio signal format. Even in the case of switching, the risk of failure of
the relay element of the switch of the output switch circuit unit 4 can be reduced.
[0040]
On the other hand, if the threshold A is set relatively large, the operation noise of the output
switch circuit 4 is substantially less likely to be heard by the user, and is not offensive. Since it
can be said that the probability that the current master volume value used by the user will be
equal to or less than the threshold A is relatively high, the operation "does not disconnect the
relay of the output switch circuit 4 (maintain the energization operation)" It is because there are
many things. In this case, since the number of operations of the output switch circuit 4 is
substantially reduced, the risk of failure of the relay element of the switch of the output switch
circuit unit 4 can be reduced.
[0041]
The operation control in the CPU 5 described above is not limited to the above case. The audio
signal amplifier 1 may be a two-channel amplifier corresponding to a stereo signal. Not only
when the surround setting is switched between the "stereo mode" and the "all channel stereo
mode", the surround settings may also be switched together with the operation of the relay
elements of the switches of the other output switch circuit unit 4. In the above embodiment, the
case where the first state in which any input audio signal is amplified and output to the
corresponding output terminal is described is switched to the second state in which the audio
signal is not output to the output terminal. Similarly, control may be performed in the case of
switching from the second state to the first state.
[0042]
Although the audio signal amplifier 1 of the above embodiment is an AV amplifier, it may be an
amplifier that uses an audio signal as an input signal and an audio reproduction device with a
built-in speaker. Further, the DSP 10 may detect the presence or absence of the audio signal or
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the volume level of the audio signal, and provide a threshold to change the operation. The audio
signal amplifier 1 may incorporate a content reproduction device such as a CD player, a DVD
player or a tuner, or a speaker.
[0043]
The audio signal amplifier 1 of the present invention can be applied not only to a stereo device
that reproduces content including digital audio signals, or to a multi-channel surround sound
reproduction device as well as video / audio equipment such as a display.
[0044]
1 audio signal amplifier 2 DA converter 3 amplifier circuit 4 output switch circuit 5 CPU (central
processing unit) 6 operation circuit 7 display circuit 8 master volume circuit 10 DSP 11 decode
circuit 12 surround mode setting circuit
09-05-2019
16
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