JP6127782B2 - Audio signal amplifier - Google Patents

Description

  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 to which a speaker is connected. About.

  In an audio device that reproduces audio, an audio signal amplifier such as an amplifier circuit that amplifies an electrically recorded audio signal and supplies the amplified audio signal to an electroacoustic transducer such as a speaker is used. The audio signal amplifier includes a volume adjustment circuit unit including a volume circuit therein, an amplification circuit unit corresponding to a power amplification stage, and an output switch circuit unit. When 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 inside thereof.

  The output switch circuit unit is provided to switch whether to output the output signal from the amplifier circuit unit to an output terminal to which the electroacoustic transducer is connected. Specifically, since the output power from the amplifier circuit unit is relatively large in the output switch circuit unit, there is a relay element that performs a cutting operation / energization operation by moving a contact point with a magnet generated by passing a current through the coil. Used. In recent audio apparatuses, in addition to a two-channel amplifier corresponding to stereo sound, for example, an AV amplifier corresponding to a plurality of multi-channel sounds such as 9.2 channels exists, so that a relay element included in the output switch circuit unit The quantity of has also increased.

  Since the relay element of the output switch circuit unit is switched depending on whether or not the audio signal is output to the output terminal, the disconnection operation / energization operation is performed quite frequently during the operation of the audio apparatus. For example, an AV amplifier that supports multi-channel audio supports switching of the audio signal format of the input audio signal in addition to performing disconnection / energization operation to protect the speaker during power on / off operation. In response to switching of the surround setting by user operation, some relay elements in the output switch circuit section are disconnected to suppress output to unused speakers corresponding to channels that do not have audio signals. There is a case to let you. This is to prevent unwanted crosstalk noise from being reproduced from a speaker that should not be used even if undesired crosstalk noise occurs in which the audio signal leaks from a channel where the audio signal exists to a channel where the audio signal does not exist. It is.

  In the output switch circuit unit configured to use the relay element, an operation sound for mechanically moving the contact is generated in accordance with the cutting operation / energization operation. As described above, the relay element of the output switch circuit section performs disconnection operation / energization operation quite frequently during the operation of the audio apparatus. As a result, for some users, the output switch circuit section that occurs frequently There is a problem that the operation sound may be uncomfortable. In particular, in a quiet environment with low ambient noise, the operation sound of the output switch circuit unit may become annoying when a plurality of relay elements perform disconnection / energization operations.

  Conventionally, in order to provide a display device with a timer function that can be controlled so as to suppress noise output from the display device itself at the time of timer setting (fan rotation sound, relay sound when the power is turned off, etc.) After setting the timer, various settings such as the screen, sound, and fan of the display device will change automatically over time, such as setting the noise generated by the display device so that it does not interfere with the user according to the timer time. There is a display device that can be set (Patent Document 1). In Patent Document 1, the power supply relay for turning on / off the AC power supply of the display device is disconnected after the standby state continues for a certain time. However, since Patent Document 1 is concerned when a relay sound is generated when using a display device or the like, by setting a certain length of time for continuing the standby state to be considerably long, the user is not concerned. It just makes the relay disconnect.

JP 2007-1335018 A

  The present invention has been made in order to solve the above-described problems of the prior art, and an object of the present invention is to suppress the generation of operation sound of the output switch circuit and to reduce the feeling of unpleasantness for the user. Is to provide.

  An audio signal amplifier according to the present invention includes a volume adjustment circuit unit that changes the volume of a plurality of input audio signals and outputs each of the input audio signals, an amplification circuit unit that amplifies each output signal from the volume adjustment circuit unit, and an amplification circuit unit Output switch circuit section for switching whether or not to output each output signal to an output terminal to which a plurality of electroacoustic transducers are respectively connected, operation of the volume adjustment circuit section, the amplification circuit section, and the output switch circuit section A sound signal amplifier comprising: a control unit that controls the control unit; and an instruction input unit that is connected to the control unit and receives a user operation including a volume control instruction to the volume control circuit unit. When the operation of the amplifier is switched 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 no audio signal is output to the output terminal, the output terminal The output switch circuit unit corresponding to is disconnected when the volume control instruction at the instruction input unit is set larger than a predetermined threshold value, and the energization operation is performed when it is set smaller than the threshold value. Control to maintain.

  Preferably, in the audio signal amplifier according to the present invention, the first state includes a case where all of the plurality of input audio signals are amplified and output to all output terminals, respectively, and the second state is that of the plurality of input audio signals. This includes a case where at least one is amplified and output to a corresponding output terminal, and an audio signal is not output to at least one output terminal.

  Preferably, in the audio signal amplifier according to the present invention, the switch of the output switch circuit unit includes a relay element that performs a disconnection operation / energization operation by moving a contact point with magnetism generated by passing a current through the coil.

  Preferably, in the audio signal amplifier of 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.

  Preferably, in the audio signal amplifier according to the present invention, 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. To switch.

  The operation of the present invention will be described below.

  An audio signal amplifier according to the present invention includes a volume adjustment circuit unit that changes the volume of a plurality of input audio signals and outputs each of the input audio signals, an amplification circuit unit that amplifies each output signal from the volume adjustment circuit unit, and an amplification circuit unit Output switch circuit section for switching whether or not to output each output signal to an output terminal to which a plurality of electroacoustic transducers are respectively connected, operation of the volume adjustment circuit section, the amplification circuit section, and the output switch circuit section And a command input unit that is connected to the control unit and receives a user operation including a volume control command to the volume adjustment circuit unit. 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 no audio signal is output to the output terminal. In the second state, the output switch circuit unit corresponding to the output terminal that does not output the audio signal is disconnected when the volume control instruction at the instruction input unit is set to be larger than a predetermined threshold, and the output switch circuit unit is less than the threshold. When it is set to a small value, control is performed so that the energization operation is maintained.

  Therefore, the audio signal amplifier disconnects the output switch circuit unit when the sound is reproduced at a relatively large volume even if the operation sound of the output switch circuit unit is generated when switching from the first state to the second state. On the other hand, when the sound is reproduced with a relatively small volume, the energization operation in the output switch circuit unit can be maintained so that the operation sound is not generated. When sound is reproduced at a relatively large volume, the operation sound of the output switch circuit unit is easily masked by the reproduced sound, so that the user hardly feels the operation sound of the output switch circuit. In addition, when sound is reproduced at a relatively low volume, since the energization operation is maintained in the output switch circuit unit corresponding to the output terminal that does not output an audio signal, no operation sound is generated. As a result, it is possible to prevent the operation sound of the output switch circuit from being felt uncomfortable for the user.

  The first state means a state where the input audio signal is intended to be amplified and output to the corresponding output terminal, and the second state means that the audio signal is output to the output terminal regardless of the operation of the output switch circuit unit. It means a state that is not intended to be output. The first state includes a case where all of the plurality of input audio signals are amplified and output to all the output terminals, and the second state amplifies at least one of the plurality of input audio signals. It may include the case of outputting to a corresponding output terminal and not outputting an audio signal to at least one output terminal. Specifically, even when the state is changed so that no audio signal is output 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. If the input audio signal consists of multiple channel components, one audio channel may be amplified and output to the corresponding output terminal, and the audio signal may not be output to the other output terminals. It is preferable to suppress the occurrence. When the sound is reproduced with a relatively large volume, the crosstalk noise tends to be relatively large. On the other hand, when the sound is reproduced with a relatively small volume, the crosstalk noise is relatively small. The audio signal amplifier according to the present invention prevents the reproduction of a large crosstalk noise by cutting the output switch circuit unit when the sound is reproduced at a relatively large volume, while the volume of the sound is relatively small. In the case of reproducing the sound, the crosstalk noise is small, so that the energization operation in the output switch circuit unit corresponding to the output terminal that does not output the sound signal is maintained. As a result, unwanted crosstalk noise can be substantially prevented from being reproduced from a speaker that should not be used, and the operation sound of the output switch circuit can be prevented from being unpleasant for the user. it can.

  In addition, the audio signal amplifier may include a relay element in which the switch of the output switch circuit unit performs a disconnection operation / energization operation by moving a contact point by a magnetism generated by passing a current through a coil. When the switch of the output switch circuit unit is a relay element, the operation sound is likely to be annoying in a quiet environment with little ambient noise. Therefore, when audio is played back at a relatively low volume, no operation sound is generated by maintaining the energization operation in the output switch circuit unit corresponding to the output terminal that does not output the audio signal. Therefore, the operation sound of the output switch circuit can be substantially prevented from being uncomfortable.

  In the audio signal amplifier, the control unit may set and store a threshold value related to the sound volume control instruction to a predetermined value based on a user operation from the instruction input unit. Whether or not the operation sound of the output switch circuit is annoying depends on the sense of each user or the difference in ambient noise, so switch between switching the output switch circuit section or maintaining the energization operation The volume control instruction to the volume adjustment circuit unit can be optimally adjusted for each user.

  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. You may make it switch. In the output switch circuit unit, whether or not the audio signal is amplified and output 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 sound is reproduced at a relatively small volume, generation of operation sound of the output switch circuit can be suppressed by maintaining the energization operation in the output switch circuit unit. In particular, depending on the content to be played, the audio signal format of the input audio signal may change frequently. The audio signal amplifier may also be set by the user so as to automatically switch the surround setting corresponding to the audio signal format. Therefore, when the sound is reproduced at a relatively low volume, the number of operations of the output switch circuit is substantially reduced. Therefore, when the switch of the output switch circuit unit includes a relay element, the relay element The risk of failure can be reduced.

  The audio signal amplifier according to the present invention suppresses the generation of the operation sound of the output switch circuit and can reduce the user's uncomfortable feeling. In addition, it is possible to substantially prevent unwanted crosstalk noise from being reproduced from a speaker that should not be used, and reduce the risk of failure of the relay element when the switch of the output switch circuit unit includes the relay element. be able to.

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 the volume control instruction | indication in CPU of an audio | voice signal amplifier. Example 1 It is a flowchart explaining the operation control in CPU of an audio | voice signal amplifier. Example 1

  Hereinafter, the audio signal amplifier according to preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

  FIG. 1 is a block diagram illustrating an audio signal amplifier 1 according to a preferred embodiment of the present invention. Specifically, the audio signal amplifier 1 is an AV amplifier that is 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) that supports stereo audio signals and multi-channel audio signals. In addition, illustration and description of a part of the structure unnecessary for the description, an internal structure, and the like are omitted.

  The audio signal amplifier 1 decodes multi-channel audio data input to a terminal adata from a content reproduction device (not shown), amplifies each channel, and connects to a speaker terminal group TSP (not shown). Output to speakers and play multi-channel audio to viewers (users). In the audio signal amplifier 1, a decoding circuit 11 configured in a DSP (Digital Signal Processor) 10 decodes multichannel audio data into 7.1 channel surround audio data. The audio data of the 7.1 channel means the front left data L, the front right data R, the front center data C, the surround left data SL, the surround right data SR, the surround back left data SBL, and the surround back right data SBR. It consists of 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 in the DSP 10 and converted into a 7.1-channel analog audio signal.

  The volume of each analog audio signal output from the DAC 2 is adjusted through a master volume circuit 8 which is a volume adjustment circuit. The volume in the master volume circuit 8 is controlled by a CPU 5 described later. Among the 7.1 channel analog audio signals, a total of 7 channels including all band components are amplified by the amplifier 3 for amplifying the respective channel audios, and output via the output switch circuit 4 composed of a plurality of switch relays. Are output to the speaker terminal group TSP. Further, the band-limited bass signal LFE is output from the terminal lfe and input to an amplifier built-in subwoofer Sub (not shown).

  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 performs a cutting operation / energizing operation by moving a contact point by a magnetism generated by passing a current through a coil, and its operation is controlled by a CPU 5 to be described later. The output switch circuit 4 corresponds to the switching of the audio signal format of the input audio signal in addition to performing the disconnection operation / energization operation so as to protect the speaker when the audio signal amplifier 1 is turned on / off. In response to switching of surround settings by user operation, to suppress output to unused speakers corresponding to channels where there is no audio signal (that is, speakers corresponding to channels where audio output is not intended) In addition, some relay elements are cut off. In addition, the switch relay generates an operation sound associated with the disconnection operation / energization operation. Therefore, in a quiet environment with low ambient noise, the user may hear the operation sound of the output switch circuit 4 of the audio signal amplifier 1.

  The audio signal amplifier 1 includes a central processing unit (CPU) 5 that controls the whole, an operation circuit 6 that includes a volume switch, and a display circuit 7 that includes a liquid crystal display panel and LEDs. Other circuit configurations are omitted in FIG. The operation circuit 6 and the display circuit 7 of the multichannel audio amplifying apparatus 1 allow the user to adjust the volume setting value related to the volume control instruction, and adjust the playback volume. Further, the CPU 5 can set and store a threshold value related to a volume control instruction, which will be described later, to a predetermined value based on a user operation from the operation circuit 6.

  The 7.1 channel surround sound data is converted into a 7.1 channel analog sound signal via 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 signal (SL), surround right speaker corresponding to surround right audio signal (SR), surround rear left speaker corresponding to surround rear left audio signal (SBL), surround This is a 7-channel system consisting of a surround rear right speaker corresponding to the rear right audio signal (SBR) and a subwoofer corresponding to the bass signal (LFE).

  A speaker used to reproduce sound in the speaker system is selected based on the sound signal format of 7.1-channel surround sound data or the surround setting in the surround mode setting circuit 12. For example, when the input sound data is stereo sound and the surround setting is “stereo mode”, the front left speaker and the front right speaker reproduce sound, and the other speakers do not reproduce sound. When the input sound data is stereo sound and the surround setting is “all channel stereo mode”, or when the input sound data is 7 channel sound and the surround setting is “surround mode (or all channel stereo mode)”. In some cases, all seven speakers play audio. 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.

  FIG. 2 is a diagram for explaining a threshold value related to a sound volume control instruction in the CPU 5 of the audio signal amplifier 1. The horizontal axis Vol. Indicates a range that can be adjusted in the range of the minimum volume level-infinite dB to the maximum 0 dB in the volume control in the master volume circuit 8. In the reproduction of movie content or music content, the volume of the master volume is often controlled in the range of about −60 to −30 dB. The CPU 5 stores a threshold value set in advance or set by the user (for example, a value A corresponding to the master volume −50 dB in the range 0 to 100). Whether the relay of the circuit 4 is cut off or whether the master volume is less than the threshold and the relay of the output switch circuit 4 is not cut off (the energization operation is maintained) is discriminated.

FIG. 3 is a flowchart for explaining operation control in the CPU 5 of the audio signal amplifier 1. Here, the CPU 5 sets the surround setting in the surround mode setting circuit 12 to “all channel stereo mode”, and the audio signal (L, R) of the output switch circuit 4.
, C, SL, SR, SBL, SBR), the case where all relays corresponding to “ON (energization)” are controlled (S101) is illustrated. A process when the CPU 5 receives a request to switch the surround setting to the “stereo mode” via the operation circuit 6 of the audio signal amplifier 1 or when the multichannel audio data changes (S102) will be described.

The CPU 5 determines whether or not the current master volume is greater than or equal to the threshold value A by volume control in the master volume circuit 8 (S103). When the threshold value A is equal to or greater than the threshold A (S103: Yes), the surround setting is switched to “stereo mode” and the relay corresponding to the audio signal (L, R) of the output switch circuit 4 is maintained “ON (energized)”. The relay corresponding to the audio signal (C, SL, SR, SBL, SBR) is controlled to “OFF (disconnect)” (S104). In this case, in the relay corresponding to the audio signal (C, SL, SR, SBL, SBR) controlled to “OFF (disconnect)”, the operation sound of the relay is generated. However, since the master volume is equal to or greater than the threshold value A, the sound is reproduced at a relatively large volume, so that the operation sound of the output switch circuit unit is masked by the reproduced sound. The operation sound of the output switch circuit 4 is rarely felt uncomfortable. Further, in this case, even if an undesirable crosstalk noise in which the audio signal leaks from the channel (L, R) where the audio signal exists to a channel where the audio signal does not exist occurs, the corresponding relay is controlled to “OFF (disconnect)”. Therefore, undesirable crosstalk noise is not reproduced from each speaker corresponding to the audio signal (C, SL, SR, SBL, SBR).

  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 “stereo mode” and the audio signal (C, Control is performed so that the relays corresponding to SL, SR, SBL, and SBR are maintained “ON (energized)” (S105). In this case, since all the relays are not controlled to be “OFF (disconnected)”, no relay operation sound is generated. Here, since the master volume is less than the threshold value A, the user does not feel the operation sound of the output switch circuit 4 uncomfortable even when the sound is reproduced with a relatively small volume. Further, in this case, even if an undesirable crosstalk noise in which the audio signal leaks from the channel (L, R) where the audio signal exists to the channel where the audio signal does not exist occurs, the audio is reproduced at a relatively low volume. Thus, the crosstalk noise is reduced, and it is possible to prevent unwanted crosstalk noise from being reproduced from each speaker substantially corresponding to the audio signal (C, SL, SR, SBL, SBR).

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 value A by volume control in the master volume circuit 8, the CPU 5 turns on the relay corresponding to the audio signal (L, R) of the output switch circuit 4. The relays corresponding to the audio signals (C, SL, SR, SBL, SBR) are controlled to be “OFF (disconnected)” (S107). In this case, since all the relays do not operate, no relay operating sound is generated. Here, since the master volume is less than the threshold value A, the user does not feel the operation sound of the output switch circuit 4 uncomfortable even when the sound is reproduced with a relatively small volume. Further, in this case, even if an undesirable crosstalk noise in which the audio signal leaks from the channel (L, R) where the audio signal exists to a channel where the audio signal does not exist occurs, the corresponding relay is controlled to “OFF (disconnect)”. Therefore, undesirable crosstalk noise is not reproduced from each speaker corresponding to the audio signal (C, SL, SR, SBL, SBR).

Next, the case where the master volume value is changed from the state of (S105) to a value greater than or equal to the threshold A (S108) will be described. When the CPU 5 determines that the current master volume is greater than or equal to the threshold value A by volume control in the master volume circuit 8, the CPU 5 turns on the relay corresponding to the audio signal (L, R) of the output switch circuit 4. The relay corresponding to the audio signal (C, SL, SR, SBL, SBR) is controlled to “OFF (disconnect)” (S109). In this case, similarly to the state of (S104), the relay operating sound is generated in the relay corresponding to the audio signal (C, SL, SR, SBL, SBR) controlled to be “OFF (disconnected)”. However, since the master volume is greater than or equal to the threshold value A, if the sound is reproduced at a relatively large volume, the operation sound of the output switch circuit unit 4 is masked by the reproduced sound. The operation sound of the circuit 4 is less likely to be uncomfortable. Further, in this case, even if an undesirable crosstalk noise in which the audio signal leaks from the channel (L, R) where the audio signal exists to a channel where the audio signal does not exist occurs, the corresponding relay is controlled to “OFF (disconnect)”. Therefore, undesirable crosstalk noise is not reproduced from each speaker corresponding to the audio signal (C, SL, SR, SBL, SBR).

  As described in the above embodiment, the audio signal amplifier 1 is in a second state in which any one of the input audio signals is amplified and output to the corresponding output terminal, and no audio signal is output to the output terminal. Even when an operation sound of the output switch circuit unit 4 is generated when switching to, the output switch circuit unit 4 can be disconnected when the sound is reproduced with a relatively large volume, When the sound is reproduced with a small volume, the energization operation in the output switch circuit unit 4 can be maintained so that the operation sound is not generated. As a result, the user feels uncomfortable with the operation sound of the output switch circuit 4 because the operation sound of the output switch circuit unit 4 is easily masked by the reproduced sound when the sound is reproduced with a relatively large volume. There is an advantage that things are reduced. In addition, it is possible to substantially prevent unwanted crosstalk noise from being reproduced from a speaker that should not be used.

  In addition, the switch of the output switch circuit unit 4 of the above embodiment is a relay element that performs a cutting operation / energization operation by moving a contact point with a magnet generated by passing a current through a coil. Other than the relay element, a switch element that generates an operation sound in a quiet environment with low ambient noise may be used. When sound is reproduced at a relatively low volume, no operation sound is generated by maintaining the energization operation in the output switch circuit unit 4 corresponding to the output terminal that does not output an audio signal. It is possible to substantially prevent the operation sound of the output switch circuit 4 from being uncomfortable.

  In the audio signal amplifier 1, the CPU 5 may set and store the threshold value A related to the sound volume control instruction to a predetermined value based on a user operation from the operation circuit 6. For example, even if the threshold A is set to be relatively small, there is an advantage that the operation sound of the output switch circuit 4 is more unobtrusive to the user than when the threshold A is not set. If the value of the current master volume used by the user is equal to or lower than the threshold value A, the operation of “not disconnecting the relay of the output switch circuit 4 (maintaining the energization operation)” is performed. This is because the number of occurrences of is reduced. In addition, since the number of operations of the output switch circuit 4 is substantially reduced, depending on the content to be reproduced, the surround setting may be performed when the audio signal format of the input audio data changes frequently, or according to the audio signal format. Even in the case of switching, the failure risk of the relay element of the switch of the output switch circuit unit 4 can be reduced.

  On the other hand, if the threshold value A is set to be relatively large, the operation sound of the output switch circuit 4 is substantially more difficult for the user to hear and has the advantage that it is not harsh. Since it can be said that there is a relatively high probability that the current master volume value used by the user will be equal to or less than the threshold value A, the operation is “do not disconnect the relay of the output switch circuit 4 (maintain the energization operation)”. This 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.

  The operation control in the CPU 5 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”, it is also possible to switch between the surround settings accompanied by the operation of the relay element of the switch of the other output switch circuit unit 4. In the above-described embodiment, a case has been described in which switching is performed from the first state in which any input audio signal is amplified and output to the corresponding output terminal to the second state in which no audio signal is output to the output terminal. Similarly, control may be performed when switching from the second state to the first state.

  Note that the audio signal amplifier 1 of the above embodiment is an AV amplifier, but may be an audio reproducing apparatus with an amplifier and a speaker built in which an audio signal is an input signal. The DSP 10 may detect the presence or absence of an audio signal or the volume level of the audio signal, and change the operation by providing a threshold value. 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.

  The audio signal amplifier 1 of the present invention can be applied not only to a stereo apparatus that reproduces content including a digital audio signal or a multi-channel surround sound reproduction apparatus, but also to a video / audio device such as a display.

DESCRIPTION OF SYMBOLS 1 Audio | voice signal amplifier 2 DA converter 3 Amplifying 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

Claims (5)

A volume adjustment circuit unit for changing the volume of a plurality of input audio signals and outputting each,
An amplification circuit unit for amplifying each output signal from the volume adjustment circuit unit;
An output switch circuit section for switching whether or not to output each output signal from the amplifier circuit section to an output terminal to which a plurality of electroacoustic transducers are respectively connected;
A control unit for controlling operations of the volume adjustment circuit unit, the amplification circuit unit, and the output switch circuit unit;
An instruction input unit that is connected to the control unit and receives a user operation including a volume control instruction to the volume adjustment circuit unit;
An audio signal amplifier comprising:
A second state in which the control unit does not output an audio signal to the output terminal from a first state in which the operation of the audio signal amplifier amplifies any one of the input audio signals and outputs the amplified signal to the corresponding output terminal. When switching to
The output switch circuit unit corresponding to the output terminal is disconnected when the volume control instruction at the instruction input unit is set larger than a predetermined threshold value, and is set smaller than the threshold value. If so, control to maintain the energization operation,
Audio signal amplifier. The first state includes a case where all of the plurality of input audio signals are amplified and output to all the output terminals, and the second state amplifies at least one of the plurality of input audio signals. And outputting to the corresponding output terminal, and not outputting an audio signal to at least one of the output terminals,
The audio signal amplifier according to claim 1. The switch of the output switch circuit unit includes a relay element that performs the disconnection operation / the energization operation by moving a contact with a magnet generated by passing a current through a coil.
The audio signal amplifier according to claim 1 or 2. The control unit sets the threshold value to a predetermined value based on a user operation from the instruction input unit and stores the threshold value.
The audio signal amplifier according to claim 1. The control unit selects and switches the first state or the second state based on an audio signal format of the input audio signal or a surround setting by a user operation from the instruction input unit,
The audio signal amplifier according to claim 1.

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