Audio signal processor and audio device

TECHNICAL FIELD

The present invention relates to an audio signal processing apparatus and an audio apparatus. In particular, the present invention relates to an audio signal processing apparatus and an audio apparatus for supplying a multi-channel audio signal.

BACKGROUND ART

Conventionally, an amplifier apparatus, connected to a reproduction apparatus serving as an audio signal source, for performing a process such as amplification to an audio signal supplied from the reproduction apparatus side, and for supplying the processed audio signal to a loudspeaker apparatus connected to the amplifier apparatus to output a sound, an apparatus called an AV amplifier apparatus (abbreviation of an audio visual center amplifier apparatus) is known. The AV amplifier apparatus is a multi-functional audio device for performing an advanced process of audio signals synchronized with video images (audio signals which are not related to the video images may be input), and is designed such that a sound field, sound quality, and the like can be set in arbitrary states.

In this AV amplifier apparatus, as audio signals to be input, in addition to an ordinary two-channel stereo audio signal, audio signals, called multi-channel audio signals, of five channels may be input. For example, audio signals of total of six channels, i.e., a front left channel, a front right channel, a center channel, a rear left channel, and a rear right channel, and a low-band dedicated channel may be input. In such a channel configuration, the low-band dedicated channel is regarded as 0.1 channel, and this channel and the five channels may be called 5.1 channels. The signal of the low-band dedicated channel is an audio signal whose band is lower than, e.g., about 120 Hz, and the signal is supplied and output to a loudspeaker apparatus, called a super woofer, for reproducing a low-band sound. When the super woofer is not used, the signal is mixed to the signals of the other channels, the signal of the low-band dedicated channel is reproduced from loudspeaker apparatuses for the other channels together with the other channels. The channels other than the low-band dedicated channel are supplied to the loudspeaker apparatuses arranged at respective positions in a room as respective channels, for example, a plurality of loudspeaker apparatuses are arranged around a listener, so that a stereophonic space is formed.

Such an AV amplifier apparatus comprises, in addition to terminals for connecting a plurality of loudspeaker apparatuses, a terminal for connecting a headphone apparatus. As described above, audio signals may be output from the plurality of loudspeaker apparatuses, and audio signal can also be output from the headphone apparatuses.

The audio signals output from the headphone terminal of the AV amplifier apparatus described above are signals of two channels, i.e., a front left channel and a front right channel. For example, the audio signals of the two channels are supplied to the AV amplifier apparatus, and a sound based on the audio signals of two front left and right channels is output from at least one pair of loudspeaker apparatuses, connected to the AV amplifier apparatus, for the front left and right channels. In this setting, a sound output from the headphone apparatus connected to the headphone terminal of the AV amplifier apparatus is basically set in the same state as that of the sound output from the loudspeaker apparatuses described above.

However, in a state in which five-channel, i.e., multi-channel audio signals are input to an AV amplifier apparatus, in a setting in which a sound based on the supplied multi-channel audio signals is output from the multi-channel loudspeaker apparatuses, connected to the AV amplifier apparatus, for the respective channels, a sound output from the headphone apparatus connected to the headphone terminal of the AV amplifier apparatus is constituted by only the sounds of the two front channels of the sounds of the five channels constituting the multi-channel audio. As a result, a user using the headphone apparatus listens to only the sounds of some channels of, e.g., the five channels.

More specifically, when the multi-channel audio signals of 5.1 channels described above is input to the AV amplifier apparatus as audio signals of a movie, voice of speech (words) synchronized with moving pictures of the movie is mainly included in the center channel, and only a sound such as music is output from the left and right loudspeaker apparatuses by the signals of the two front left and right channels. In this case, only a sound (music in the above example) included in the two front left and right channels is output from the headphone apparatus connected to the AV amplifier apparatus, words of the movie included in the center channel cannot be heard. The user cannot hear various sound effects or the like included in the rear channels of the 5.1 channels by means of the headphone apparatus.

In order to solve this problem, for example, when the headphone apparatus is connected, a setting is preferably made such that the process of converting multi-channel audio into two-channel audio in the AV amplifier apparatus is performed. However, in this setting, a sound output from the stationary loudspeaker apparatus connected to the AV amplifier apparatus is also of two-channel audio obtained by converting the multi-channel audio.

Therefore, when appropriate multi-channel audio is heard by using a headphone apparatus in a conventional AV amplifier apparatus, not only switching of a switch for turning off the stationary loudspeakers is simply performed, an operation for setting the processing state of multi-channel audio by a mode setting must be performed. When the state in which the headphone apparatus is used is returned to the state in which the stationary loudspeaker apparatus are used, an operation of returning the state to the original setting state must be performed. A problem that the operation is very complex is posed.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to make it possible that an outputting operation of multi-channel audio signals from a loudspeaker apparatus and an outputting operation of the signals from a headphone apparatus are preferably performed.

In the first invention, an audio signal processing apparatus comprises, an input unit to which at least an audio signal of a left channel, an audio signal of a right channel, and an audio signal of a center channel are supplied, a first output terminal unit for outputting the audio signal of the left channel, the audio signal of the right channel, and the audio signal of the center channel which are supplied to the input unit, a mixing unit for mixing the audio signal of the center channel to the audio signal of the left channel and mixing the audio signal of the center channel to the audio signal of the right channel to output the mixed signals as audio signals of two channels, and a second output terminal unit for outputting the audio signals of the two channels from the mixing unit. In this manner, the audio signal of the left channel, the audio signal of the right channel, and the audio signal of the center channel are independently output from the output terminal unit, and the audio signals of the two channels obtained by mixing a signal component of the center channel to the audio signal of the left channel and the audio signal of the right channel are output from the second output terminal unit, so that the audio signals of two different types of channel forms can be output from one audio signal processing apparatus. For example, the first output terminal unit is connected to a stationary loudspeaker apparatus, and the second output terminal unit is connected to a headphone apparatus, so that an outputting operation of an audio signal of a channel form being appropriate to the stationary loudspeaker apparatus and an outputting operation of an audio signal of a channel form being appropriate to the headphone apparatus can be properly performed by selection of the output terminal units.

In the second invention, in the audio signal processing apparatus according to the first invention, the audio signal processing apparatus further comprises a switching unit for selectively supplying the audio signal of the left channel and the audio signal of the right channel supplied to the second output terminal unit through the input unit and the audio signals of the two channels from the mixing unit. In this manner, a switching operation between the state in which the outputting operation of the audio signal which is mixed with the audio signal of the center channel is performed, and the state in which the outputting operation of the audio signal which is not mixed with the audio signal of the center channel can be easily performed by operating the switching unit.

In the third invention, in the audio signal processing apparatus according to the second invention, the switching unit selectively supplies the audio signal of the left channel and the audio signal of the right channel supplied to the first output terminal unit through the input unit and the audio signals of the two channels from the mixing unit. In this manner, the audio signal of the left channel and the audio signal of the right channel supplied to the first output terminal unit can be easily output from the second output terminal unit by a switching operation of the switching unit.

In the fourth invention, an audio apparatus comprises an input unit to which at least an audio signal of a left channel, an audio signal of a right channel, and an audio signal of a center channel are supplied, a first output terminal unit, to which a plurality of loudspeaker apparatuses are connected, for outputting at least the audio signal of the left channel and the audio signal of the right channel of the audio signal of the left channel, the audio signal of the right channel, and the audio signal of the center channel supplied to the input unit, a mixing unit for mixing the audio signal of the center channel to the audio signal of the left channel and mixing the audio signal of the center channel to the audio signal of the right channel to output the mixed signals as audio signals of two channels, and a second output terminal unit to which the audio signals of the two channels from the mixing unit and to which a headphone apparatus is connected. In this manner, the audio signal of the left channel, the audio signal of the right channel, and the audio signal of the center channel are independently supplied to a plurality of loudspeaker apparatuses connected to the first output units, and the audio signals of the respective channels are independently output from the loudspeaker apparatuses. The signals obtained by mixing the audio signal of the center channel to the audio signal of the left channel and the audio signal of the right channel are supplied to the headphone apparatus connected to the second output terminal unit, and the audio signals including the center channel are output from the headphone apparatus.

In the fifth invention, in the audio apparatus according to the fourth invention, the audio apparatus further comprises a switching unit for selectively supplying the audio signal of the left channel and the audio signal of the right channel supplied to the second output terminal unit through the input unit and the audio signals of the two channels from the mixing unit. In this manner, a switching operation between the state in which the outputting operation of the audio signal which is mixed with the audio signal of the center channel from the headphone apparatus connected to the second output terminal unit is performed, and the state in which the outputting operation of the audio signal which is not mixed with the audio signal of the center channel can be easily performed by operating the switching unit.

In the sixth invention, in the audio apparatus according to the fifth invention, the switching unit selectively supplies the audio signal of the left channel and the audio signal of the right channel supplied to the first output terminal unit through the input unit and the audio signals of the two channels from the mixing unit. In this manner, the audio signal of the left channel and the audio signal of the right channel supplied from the first output terminal unit to the loudspeaker apparatuses can be easily output from the second output terminal unit to the headphone apparatus by a switching operation of the switching unit.

In the seventh invention, in the audio apparatus according to the fourth invention, the first output terminal unit comprises a first output unit for outputting at least the audio signal of the left channel and the audio signal of the right channel of the audio signal of the left channel and the audio signal of the right channel supplied to the input unit and the audio signal of the center channel, and a second output unit for respectively outputting the audio signal of the left channel, the audio signal of the right channel, and the audio signal of the center channel supplied to the input unit. In this manner, loudspeaker apparatuses can be independently connected to the first output unit and the second output unit, and a channel configuration of the loudspeaker apparatuses respectively connected to the output unit can be changed.

In the eighth invention, in the audio apparatus according to the seventh invention, the apparatus further comprises a switching unit for selectively supplying at least the audio signal of the left channel and the audio signal of the right channel of the audio signal of the left channel and the audio signal of the right channel supplied to the input unit and the audio signal of the center channel to at least one output unit of the first output unit and the second output unit. In this manner, outputting operations of at least the audio signal of the left channel and the audio signal of the right channel can be easily selected by operating the switching unit.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1

is a block diagram showing an example of an amplifier apparatus according to one embodiment of the present invention.

FIG. 2

is a diagram showing a configuration according to one embodiment of the present invention.

FIG. 3

is a diagram showing an audio signal output unit according to one embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

One embodiment of the present invention will be described below with reference to the accompanying drawings.

In this embodiment, for example, the present invention is applied to an amplifier apparatus which can perform an advanced process of audio signals synchronized with video images and audio signals which are not related to video images. A configuration of a stereo apparatus to which an amplifier apparatus according to the present invention is connected will be described below with reference to FIG.

1

. To the amplifier apparatus

10

according to the present invention, a disc reproducing apparatus

1

for reproducing audio signals from an optical disc called a compact disc (CD) as an audio apparatus for reproducing audio signals, a tape recording/reproducing apparatus

2

for using a magnetic tape of a tape cassette to record and reproduce audio signals, and a disc recording/reproducing apparatus

3

for using a recordable optical disc such as a photomagnetic disc to record and reproduce audio signals are connected. The audio signals reproduced from the respective recording media by the apparatuses

1

,

2

, and

3

are supplied to the amplifier apparatus

10

.

To the amplifier apparatus

10

, as a video device for reproducing video signals and audio signals, a video disc reproducing apparatus

4

for reproducing video signals and audio signals from an optical disc called a DVD (Digital Video Disc or Digital Versatile Disc) or the like and a video tape recording/reproducing apparatus

5

for using a magnetic tape to record and reproduce video signals and audio signals are connected. The video signals and the audio signals reproduced from the recording media by the apparatuses

4

and

5

are supplied to the amplifier apparatus

10

.

As a video device for televising video signals selected by the amplifier apparatus

10

from the video signals supplied from the video disc reproducing apparatus

4

and the reproducing apparatus

5

to the amplifier apparatus

10

, a monitor image-receiver

6

is connected to the amplifier apparatus

10

. In addition, as loudspeakers for reproducing audio signals selected by the amplifier apparatus

10

from the audio signals supplied to the amplifier apparatus

10

, front loudspeakers

7

L and

7

R arranged on the front left and right, a center loudspeaker

7

C arranged at the front center, rear loudspeakers

7

SL and

7

SR arranged on the rear left and right, and a super woofer

7

SW arranged at an arbitrary position. The super woofer

7

SW is a loudspeaker having a function of outputting a sound having a frequency lower than a preset frequency, e.g., 120 Hz. The other loudspeakers

7

C,

7

L,

7

R,

7

SL, and

7

SR are ordinary loudspeakers for outputting sounds having frequencies higher than the frequency of the sound output from the super woofer

7

SW. These loudspeaker apparatuses

7

C,

7

L,

7

R,

7

SL,

7

SR, and

7

SW are stationary loudspeaker apparatuses.

In the amplifier apparatus

10

, for example, a headphone terminal unit

53

is arranged on a front-surface panel. When a plug

8

a

of a headphone apparatus

8

is inserted into and connected to the headphone terminal unit

53

, a user can hear audio signals selected by the amplifier apparatus

10

by using the headphone apparatus

8

.

As the audio signals supplied to the amplifier apparatus

10

, audio signals of two left and right channels may be used, or audio signals of multi-channels which are larger in number than that of two channels may be used. As audio channels of a large number of channels, for example, signals of six channels (to be referred to as 5.1 channels hereinafter), i.e., a front left channel, a front right channel, a center channel, a rear left channel, a rear right channel, and a low-band frequency dedicated channel are used. The audio signals of the 5.1 channels are supplied to the amplifier apparatus

10

, and processes such as separation and amplification are performed to the signals of the channels of the audio channels of the 5.1 channels. Thereafter, the signals are supplied to the loudspeakers

7

C,

7

L,

7

R,

7

SL,

7

SR, and

7

SW of the channels having the same arrangement and corresponding to the audio signals of the channels to output sounds. The audio signals of the 5.1 channels may also be supplied from another device. However, in the example shown in

FIG. 1

, the audio signals are one of digital audio signals supplied from, e.g., the video disc reproducing apparatus

4

, and are RF-modulated audio signals obtained at an digital RF input unit

11

(to be described later).

A low-band dedicated channel existing when the digital audio signals of the 5.1 channels described above are used is a channel in which only an audio signal having a frequency lower than, e.g., about 120 Hz exists. A mode in which the low-band dedicated channel is called an LFE mode. In this embodiment, as the low-band dedicated channel, the audio signal having a frequency lower than about 120 Hz is set. However, the lower limit of the frequency of the audio signal is changed depending on a music source or the like recorded on a stereo apparatus or a recording medium. A digital audio signal in which a low-band dedicated channel exists in the LFE mode includes any identifier signal representing that the low-band dedicated channel exists. In multi-channel audio except for 5.1 channel digital audio, the same low-band dedicated channel may be used to set the LFE mode. When the audio signals of two channels are input to the amplifier apparatus

10

, the input signals of the two channels are processed by the amplifier apparatus

10

to generate channel components of the rear left and right channels and the like, and the channels are supplied the above loudspeakers

7

C,

7

L,

7

R,

7

SL,

7

SR, and

7

SW of the channels to output sounds.

The internal configuration of the amplifier apparatus

10

will be described below with reference to FIG.

2

.

FIG. 2

is a block diagram showing a processing system of audio signals of the amplifier apparatus

10

and a control system of the processing system of the audio signals. The input unit for a digital audio signal included in the amplifier apparatus

10

has a digital RF input unit

11

, two optical digital input units

12

and

13

to which optical fiber cables are connected and to which digital data are supplied, and a coaxial digital input unit

14

to which a coaxial cable is connected and to which digital data is supplied. The digital data obtained from the digital input units

11

to

14

are supplied to a change-over switch

22

controlled by a system controller

30

. Under the control of the system controller

30

, the change-over switch

22

selects digital data from one of the input units described above, and supplies the selected audio data to a digital signal processor (to be referred to as a DSP hereinafter)

23

. In this case, the RF-modulated digital data obtained in the digital RF input unit

11

is demodulated in an RF demodulation unit

21

, and then supplied to the change-over switch

22

. This amplifier apparatus

10

comprises an output unit

15

for a digital audio signal, and supplies the digital data (e.g., digital data supplied to the DSP

23

may be used) selected by the change-over switch

22

and any digital data of the digital data from the other input units to an external electronic device connected to the output unit

15

, so that recording or the like can be performed by the external electronic device.

As input units for analog audio signals, four analog input units

16

,

17

,

18

, and

19

are arranged in the amplifier apparatus

10

. Analog audio signals supplied through the analog input units

16

to

19

are supplied to a change-over switch

24

controlled by the system controller

30

, the audio signal from one of the analog input units

16

to

19

is selected. The audio signal selected by the change-over switch

24

is converted into digital data, and then supplied to the DSP

23

. This amplifier apparatus

10

comprises an output unit

20

for an analog audio signal, and supplies the audio data (e.g., an analog audio signal supplied to the DSP

23

may be used) selected by the change-over switch

24

and any analog audio signal of the analog audio signals from the other input units to an external electronic device connected to the output unit

20

, so that recording or the like can be performed by the external electronic device.

In the DSP

23

, required processes are performed to the audio data supplied through the switch

22

. The processes performed by the DSP

23

are, for example, a surround process in which a sound field reproduced by audio signals of the channels is set to be an arbitrary sound field or set in an acoustic state, a process of converting the number of channels, a process of converting audio signals of, e.g., two channels into audio signals of 5.1 channels, and processes reverse thereto. These processes are digitally processed. The processes performed in the DSP

23

are performed on the basis of the control of the system controller

30

.

A digital audio signal output from the DSP

23

is supplied to a digital/analog converter (DAC)

25

to be converted into an analog audio signal. A low-pass filter

26

removes a harmonic component, i.e., a high-frequency component from the analog audio signal output from the digital/analog converter (DAC)

25

. Thereafter, the analog audio signal is supplied to an amplifier unit

27

and amplified by the amplifier unit

27

. An output signal from the amplifier unit

27

is subjected by an output process such as a mute process by an output processing unit

28

as needed, and is supplied to two loudspeaker terminal units

51

and

52

. In addition to the loudspeaker terminal units

51

and

52

, a headphone terminal unit

53

is arranged in the amplifier apparatus

10

. An audio signal processed to be heard by a headphone is supplied to the headphone terminal unit

53

. Audible sounds based on the audio signals supplied from the loudspeaker terminal units

51

and

52

are output from the loudspeaker apparatuses

7

, i.e., as shown in

FIG. 1

, the loudspeaker apparatuses

7

L,

7

R,

7

C,

6

SL, and

7

SW of the respective channels, and an audible sound based on the audio signal supplied from the headphone terminal unit

53

is also output from the headphone apparatus

8

connected to the headphone terminal unit

53

. The details of a configuration in which audio signals output from the output processing unit

28

are supplied to the respective terminal units

51

,

52

, and

53

will be described below.

The system controller

30

which controls the processes in the amplifier apparatus

10

is constituted by an arithmetic operation circuit called a microcomputer. An infrared signal from a remote control apparatus which received by an infrared signal receiving unit

31

and signals based on the operations of a tact key switch

32

operated by an operation button arranged on the front panel of the amplifier apparatus

10

, a rotary encoder

33

connected to a dial thumbscrew arranged on the front panel of the amplifier apparatus

10

, the system controller

30

, and a master volume

34

are supplied to the system controller

30

. The system controller

30

performs various settings based on the signals supplied from the switch

32

, the encoder

33

, and the volume

34

and control signal operations of the respective parts. The rotary encoder

33

is a rotary operation switch for performing input switching, i.e., function switching. The master volume

34

is a volume for adjusting the volumes of outputs from the loudspeaker apparatuses

7

L,

7

R,

7

C,

7

SL,

7

SR, and

7

SW or the headphone apparatus

8

.

The amplifier apparatus

10

comprises a display unit

40

constituted by a fluorescent display tube or the like. A display control signal for controlling a display is supplied from the system controller

30

to a display drive circuit

35

, so that a display operation in the display unit

40

is controlled by the system controller

30

. In this case, an area in which arbitrary characters and numerals can be displayed and an area in which predetermined characters and graphics can be displayed are formed on the display unit

40

. On the display unit

40

, various operation states such as a function switching state and a surround process state are displayed with predetermined specific colors.

The details of a configuration in which the audio signals processed by the output processing unit

28

of the amplifier apparatus

10

according to the present invention are supplied to the terminal units

51

,

52

, and

53

to which the loudspeaker apparatuses

7

L,

7

R,

7

SL, and

7

SW or the headphone apparatus

8

are connected will be described below with reference to FIG.

3

.

Terminals

50

L,

50

R,

50

C,

50

LFE,

50

SL, and

50

SR are terminals to which audio signals converted into analog signals by the digital/analog converter

25

of the amplifier apparatus

10

, e.g., analog audio signals corresponding to outputs from the low-pass filter

26

in

FIG. 2

are supplied. The audio signal of the front left channel is supplied to the terminal

50

L, the audio signal of the front right channel is supplied to the terminal

50

R, the audio signal of the center channel is supplied to the terminal

50

C, the audio signal of the low-band dedicated channel is supplied to the terminal

50

LFE, the audio signal of the rear left channel is supplied to the terminal SL, and the audio signal of the rear right channel is supplied to the terminal

50

SR. The audio signals of the channels supplied to the terminals

50

L,

50

R,

50

LFE,

50

SL, and

50

SR are supplied to terminals

51

L,

51

R,

51

C,

51

LFE,

51

SL, and

51

SR for the channels of the first loudspeaker terminal unit

51

through amplifier units

27

L,

27

R,

27

C,

27

LFE,

27

SL, and

27

SR (corresponding to the amplifier unit

27

in

FIG. 2

) arranged for the respective channels. In the amplifier units

27

L,

27

R,

27

C,

27

LFE,

27

SL, and

27

SR of the respective channels, amplification processes having relatively large outputs which can drive so-called stationary loudspeaker apparatuses, e.g., amplifications of about several ten to one hundred and several ten W are performed.

Here, an output signal from the amplifier unit

27

L for the front left channel and an output signal from the amplifier unit

27

R for the front right channel are supplied to the first loudspeaker terminal unit

51

through switches

59

L and

59

R. When these switches

59

L and

59

R are switched, the audio signals of the front left and right channels can also supplied to loudspeaker terminals

52

L and

52

R for the front left and right channels of the second loudspeaker terminal unit

52

. The switches

59

L and

59

R are designed such that the supply of the audio signal to the first loudspeaker terminal unit

51

and the supply of the audio signal to the second loudspeaker terminal unit

52

can be independently selected. The switches

59

L and

59

R can also supply the audio signals to the loudspeaker apparatuses connected to both the terminal units

51

and

52

at once. However, the second loudspeaker terminal unit

52

is a terminal to which only loudspeaker apparatuses

7

L′ and

7

R′ of the two front left and right channels can be connected.

FIG. 3

shows the example in which the loudspeaker apparatuses corresponding to the respective channels are connected to both the first loudspeaker terminal unit

51

and the second loudspeaker terminal unit

52

. However, in fact, only the terminal unit of one of the systems may be used.

Switches

58

L and

58

R for making a branch to the headphone terminal unit

53

side are arranged on the input unit side of the amplifier unit

27

L for the front left channel and the input unit side of the amplifier unit

27

R for the front right channel. The details of switching processes in these switches

58

L and

58

R will be described later.

A configuration for branching audio signals supplied from the terminals

50

L to

50

R to the headphone terminal unit

53

side will be described below. The audio signals of the respective channels supplied through the terminals

50

L,

50

R,

50

C,

50

LFE,

50

SL, and

50

SR are branched to the system for the headphone terminal independently of the system on the loudspeaker terminal units

51

and

52

described above, and are subjected to a mixing process (e.g., an addition process in the example shown in

FIG. 3

) for making audio signals of two channels. More specifically, the audio signal of the front left channel supplied from the terminal

50

L is supplied to a mixer

55

L through a buffer amplifier

54

L, the audio signal of the center channel supplied from the terminal

50

C is supplied to the mixer

55

L through a buffer amplifier

54

C, and the audio signal of the center channel is mixed to the audio signal of the front left channel. The audio signal of the front right channel supplied from the terminal

50

R is supplied to a mixer

55

R through a buffer amplifier

54

R, the audio signal of the center channel supplied from the terminal

50

C is supplied to the mixer

55

R through the buffer amplifier

54

C, and the audio signal of the center channel is mixed to the audio signal of the front left channel.

The audio signal of the front left channel mixed with the audio signal of the center channel by the mixer

55

L is supplied to a mixer

56

L, the audio signal of the rear left channel supplied from the terminal

50

SL is supplied to the mixer

56

L through a buffer amplifier

54

SL, and the audio signal of the rear left channel is mixed to the audio signal of the front left channel. The audio signal of the front right channel mixed with the audio signal of the center channel by the mixer

55

R is supplied to a mixer

56

R, the audio signal of the rear right channel supplied from the terminal

50

SR is supplied to the mixer

56

R through a buffer amplifier

54

SR, and the audio signal of the rear right channel is mixed to the audio signal of the front right channel.

In addition, the audio signal of the left channel mixed with the audio signal of the rear channel by the mixer

56

L is supplied to a mixer

57

L, the audio signal of the low-band dedicated channel supplied from the terminal

50

LFE is supplied to the mixer

57

L through a buffer amplifier

54

LFE, and an audio signal consisting of a low-frequency component is mixed to the audio signal of the left channel. The audio signal of the right channel mixed with the audio signal of the rear channel by the mixer

56

R is supplied to a mixer

57

R, the audio signal of the low-band dedicated channel supplied from the terminal

50

LFE is supplied to the mixer

57

R through the buffer amplifier

54

LFE, and an audio signal consisting of a low-frequency component is mixed to the audio signal of the right channel.

The audio signal of the left channel mixed by the mixer

57

L is supplied to an amplifier unit

27

HL of the left channel for the headphone through the switch

58

L, and the audio signal of the left channel for the headphone amplified by the amplifier unit

27

HL is supplied to a left-channel terminal

53

L of the headphone terminal unit

53

. The audio signal of the right channel mixed by the mixer

57

R is supplied to an amplifier unit

27

HR of the right channel for the headphone through the switch

58

R, and the audio signal of the right channel for the headphone amplified by the amplifier unit

27

HR is supplied to a right-channel terminal

53

R of the headphone terminal unit

53

. In the amplifier units

27

HL and

27

HR for the headphone, amplification processes having relatively small outputs which can drive small loudspeaker units built in the headphone apparatus

8

, e.g., amplifications of about several to several ten mW are performed.

The switches

58

L and

58

R arranged on the previous stages of the amplifier units

27

HL and

27

HR for the headphone are switches for the audio signals which are mixed by the mixers

55

L,

55

R,

56

L,

56

R,

57

L, and

57

R, the audio signals which are not mixed, i.e., the audio signals supplied from the terminals

50

L and

50

R to be interlocked with each other. Therefore, when the switches

58

L and

58

R are switched, as the audio signals amplified by the amplifier units

27

HL and

27

HR for the headphone, the audio signal obtained by mixing other channel components to the front left and right channels and the audio signal consisting of only the front left and right channel components can be selected. Depending on the switching states of the switches

58

L and

58

R, audio signals of two channels mixed by the mixers

55

L,

55

R,

56

L,

56

R,

57

L, and

57

R can also be supplied to the loudspeaker terminal units

51

and

52

in place of the audio signals of the two front channels obtained by the terminals

50

L and

50

R. The switching operations of the switches

58

R,

58

L,

59

R, and

59

L may be performed by the operation of the change-over switches of the front panel of the amplifier apparatus

10

, or the switches

58

R,

58

L,

59

R, and

59

L may be switched to be interlocked with the operation of a mode switching operation unit, for a reproduction mode, arranged on the front panel of the amplifier apparatus

10

.

In the configuration shown in

FIG. 3

, a basic output processing configuration for an audio signal is shown. The configuration for a muting process is omitted.

When the output processing unit

28

of an audio signal is constituted as described above, both a reproduction output of the audio signals from the stationary loudspeaker apparatuses

7

L′,

7

R′ to

7

L,

7

R,

7

C,

7

SW,

7

SL, and

7

SR connected to the loudspeaker terminal units

51

and

52

and a reproduction output of an audio signal from the headphone apparatus

8

connected to the headphone terminal unit

53

can be preferably performed. In particular, as a process selected by switching in the switches

58

L and

58

R, the audio signals supplied to the loudspeaker terminal units

51

and

52

are used as the audio signals of the front left and right channels obtained by the terminals

50

L and

50

R, and the audio signals supplied to the headphone terminal unit

53

are used as the audio signals of the left and right channels mixed with the audio signals of the other channels by the mixers

55

L,

55

R,

56

L,

56

R,

57

L, and

57

R. In this manner, sounds which can reproduce a sound field based on multi-channel audio signals are output from the loudspeaker apparatuses

7

L,

7

R,

7

C,

7

SW,

7

SL, and

7

SR connected to the first loudspeaker terminal unit

51

, and sounds based on the audio signals obtained by mixing the components of other channels to the audio signals of the two left and right channels are output from the headphone apparatus

8

connected to the headphone terminal unit

53

. Therefore, when multi-channel audio serving as speech of a movie reproduced from a video disc or the like is output, a sound field obtained by proper stereo acoustic sounds can be reproduced from the loudspeaker apparatuses

7

L,

7

R,

7

C,

7

SW,

7

SL, and

7

SR, and reproduced sounds based on audio signals including all words, sound effects, and low-band sounds can be heard with the headphone apparatus

8

.

In this case, the output processing unit

28

can simultaneously output outputs based on the multi-channel audio signals from the loudspeaker apparatuses

7

L,

7

R,

7

C,

7

SW,

7

SR, and

7

SL and outputs based on the audio signals two synthesized channels from the headphone apparatus

8

. For example, in the state in which sounds based on audio signals are output from the loudspeaker apparatuses, the plug of the headphone apparatus

8

is inserted into the headphone terminal unit

53

, and only a switch operation for stopping outputting of sounds from the loudspeaker apparatuses

7

L,

7

R,

7

C,

7

SW,

7

SR, and

7

SL arranged on the front panel of the amplifier apparatus is performed, so that the multi-channel audio signals can be heard with the headphone apparatus

8

. In this case, a user need not perform a mode setting for switching the process states of supplied multi-channel audio signals according to hearing using the headphone apparatus

8

at all, and the user can easily perform switching between a hearing state in which the loudspeaker apparatuses

7

L to

7

SL are used and a hearing state in which the headphone apparatus

8

is used. In a state in which reproduced sounds based on multi-channel audio signals are output from the loudspeaker apparatuses

7

L to

7

SL of the respective channels, and, at the same time, sounds based on audio signals synchronized in two channels can be heard from the headphone apparatus

8

.

In the amplifier apparatus described above, the audio signals of the center channel and the rear left and right channels and the audio signal of the low-band dedicated channel are mixed to the audio signals of the two front left and right channels to output the mixed audio signals from the headphone terminal unit. However, only the audio signal of one of the other channels constituting the multi-channel may be mixed to the audio signals of the two front left and right channels. For example, only the audio signal of the center channel may be mixed to the audio signals of the two front left and right channels, and the mixed audio signals of the two channels may be supplied to the headphone terminal unit. In this manner, when speech of, e.g., a movie is opened by using a headphone apparatus, the audio signal of a center channel including at least words are mixed to the audio signals of left and right channels. For this reason, the words are output from the left and right loudspeaker units of the headphone apparatus.

In addition, the audio signal of the center channel may be mixed to the two front left and right channels, and the rear left and right channels may be mixed to the two front left and right channels. In this manner, sound effects included to the rear channel can be output from the headphone apparatus.

In the example described above, signals supplied from a video disc reproducing apparatus to an amplifier apparatus are used as multi-channel audio signals of 5.1 channels or the like. However, multi-channel audio signals supplied from another video device or an audio device, e.g., multi-channel audio signals obtained by satellite broadcast waves received by a tuner may be processed.

In the example described above, audio signals constituted by 5.1 channels are used as multi-channel audio signals. However, audio signals of three or more other channels may be used.

In addition, in the example described above, the present invention is applied to the process in an audio device called an AV amplifier apparatus. However, the present invention can also be applied to the case in which the same process described above is performed by an audio device integrated with another audio device such as a system stereo apparatus.

Number	Date	Country
3-85831	Apr 1991	JP
9-200897	Jul 1997	JP

Audio signal processor and audio device

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Date Filed

Date Issued

Inventors

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CPC

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Abstract

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