JP2002027600A - Multi-channel audio reproducing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-channel audio reproducing system capable of outputting a sound having large volume and being excellent in the sense of presence even when reproducing a two channel audio signal in addition to a multi-channel audio signal. SOLUTION: In this multi-channel audio reproducing system which is provided with D/A converters, power amplifiers, and speakers for the respective output channels of a digital signal processing circuit, relay circuits are arranged between the power amplifiers and the speakers so that the speaker of a two channel system can be connected with the power amplifier of another channel other than the two channel system among the multi-channels by switching the contacts of the relay circuits. At the reproducing of the two channel audio signal, the signal processing of a digital signal processing circuit 1 and the relay circuits are switched so that a BTL output mode can be set for driving a speaker A8 of an L channel by signals amplified by a power amplifier A4 of the L channel and a power amplifier B5 of the other channel. Also, an R channel is treated in the same way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-channel audio reproduction system, and more particularly to a multi-channel audio signal as well as a two-channel audio signal having a large sound volume and a realistic sound when reproducing a two-channel audio signal. The present invention relates to a multi-channel audio reproduction system that produces an excellent sound effect.

[0002]

2. Description of the Related Art In a multi-channel audio reproduction system, for each output channel of a digital signal processing circuit,
It is successively provided with a D / A converter, a power amplifier, and a speaker, and has a high fidelity and a realistic sound effect.

Here, the configuration of an optical disk player having a multi-channel audio reproduction system will be described with reference to FIGS. Figure 2 shows the optical disk
FIG. 3 is a block diagram showing a configuration of a player, FIG. 3 is a block diagram showing a configuration of a signal detection unit and a signal processing and control unit, and FIG.
Block diagram showing the configuration of the / A conversion and amplification unit and the output unit;
5 is a perspective view showing a speaker system of an output unit. As shown in FIG. 2, the optical disk player 20 includes a signal detection unit 22 that detects an audio signal and a video signal stored in the optical disk, a signal processing and control unit 24,
The D / A converter / amplifier unit 26 and the output unit 28 are provided.

[0004] As shown in FIG. 3, the signal detector 22 includes a spindle motor 33 for rotating the optical disk 31, an optical pickup 34 for detecting an optical signal, and a threading motor for moving the optical pickup 34 in the radial direction of the optical disk 31. 35, and an RF / EQ amplifier 36 for performing an equalizing process on the photodetection signal. On the optical disk 31, a compressed digital video signal and a digital audio signal accompanying it are recorded. The optical pickup 34 irradiates the optical disk 31 with the laser beam converged by the objective lens, passes the laser beam reflected and diverged on the optical disk 31 through an optical system such as an objective lens, and then detects the converged laser beam. Then, the light detection signal is output to the RF / EQ amplifier 36. The RF / EQ amplifier 36 performs an equalizing process on the light detection signal.

[0005] As shown in FIG. 3, the signal processing and control section 24 is composed of a signal processing system and a control system. The signal processing system includes an RF signal processing block 39 that performs RF signal processing on a signal output from the RF / EQ amplifier 36 to convert the signal into a binary digital signal, and an image that decodes a digital signal output from the RF signal processing block 36. An audio signal decoding block 42, a digital audio signal processing block 45 for processing the decoded audio signal, and the D-RAM 41 described in the video / audio signal decoding block 42 as a storage device are provided. The control system controls the rotation of the spindle motor 33 via the motor driver 38 and controls the threading motor 35 to perform the tracking servo of the optical pickup 34 and the servo block 40 for performing the focus servo of the optical pickup 34. The system includes a system control microcomputer 43 for controlling the entire system of the player 20, and an interface microcomputer 44 interposed between the microcomputer 43 and the operation buttons 54 and the operation display 55.

As shown in FIG. 4, the D / A conversion and amplifier section 26 has an audio signal D / A conversion block 46 for converting a digital signal into an analog signal as an audio signal system.
An audio signal attenuating block (VOL) 52, three audio signal amplifier blocks 48, and a relay circuit 53 are provided, and a video signal D / A conversion block 47 is provided as a video signal system. The output unit 28 includes a plurality of full-range speakers 49 and a low-frequency dedicated speaker 50 as an audio signal system, and a video output device 51 as a video signal system.

[0007] The RF signal output from the photodetector of the optical pickup 34 is subjected to equalizing processing by an RF / EQ amplifier 36, and then supplied to an RF signal processing block 39 to be decoded and subjected to binary processing. It is converted to a digital signal. The digital signal output from the RF signal processing block 39 is input to the video / audio decoding block 42. When the digital signal from the RF signal processing block 39 is a signal obtained by mixing video and audio and compressing it,
The video / audio decoding block 42 decodes the
A decompressed digital video signal, a decompressed digital audio signal, or a digital signal obtained by compressing audio of a plurality of channels is output. The video / audio signal decoding block 42 is connected to a D-RAM 41 as storage means, and data is transferred between the video / audio signal decoding block 42 and the D-RAM 41.

The decompressed digital video signal output from the video / audio signal decoding block 42 is supplied to a video signal D / A conversion block 42 where it is D / A converted, and the obtained analog video signal is For example, the image is supplied to an image output device 51 of a television receiver and is displayed. On the other hand, the digital audio signal output from the video / audio signal decoding block 42 is sent to the digital audio signal processing block 45. In the case of a digital signal obtained by compressing audio of a plurality of channels, the digital audio signal processing block 45 further expands the digital signal, and the expanded digital audio signal of the plurality of channels is sent to an audio signal D / A conversion block 46. Is output. In the digital audio signal processing block 45, filtering processing, delay processing, and the like can be digitally calculated with respect to the input of the expanded digital audio signal, and the processing effect can be added to the output signal.

In the audio signal D / A conversion block 46,
The digital audio signal is D / A converted and output as a plurality of channels of analog audio signals. This analog audio signal is amplified by an audio amplifier circuit 48, and is further switched by a plurality of relay circuits 53 provided for each channel. It can be driven. The audio signal attenuation block (VOL) 52 includes an audio signal D / A conversion block 46.
Adjust the level of the analog signal output from. These RF signal processing block 39, video / audio decoding block 42, and video signal D / A conversion block 47
It is controlled by the system control microcomputer 43. D / A for audio signal
The conversion block 46 and the digital audio signal processing block 45 include an interface microcomputer 44.
More controlled.

Referring to FIG. 5, a speaker system 60 including the above-described full-range speaker 49 and low-frequency dedicated speaker 50 will be further described. For example, in the case of 5.1 channels, that is, Dolby (registered trademark) digital 5.1 which is defined as one of the audio standards of DVD.
When reproducing an audio signal of a multi-channel format on one channel (5.1-channel DTS), the speaker system 60 includes five satellite speakers 62 and 64 as a plurality of full-range speakers 49 as shown in FIG. , 66, 68, and 70, and a subwoofer speaker 72. One of the satellite speakers is a speaker 50 dedicated to bass reproduction. Here, the Dolby Digital is a multi-track sound system based on a digital audio signal compression system developed by US Dollar Laboratories, and the 5.1-channel audio reproduction system is a Dolby Digital AC-3 audio reproduction system. The 5.1 "0.1 refers to the channel for the super woofer. When reproducing the 5.1 channel audio signal using the speaker system 60, the sound from all speakers is output. Is output.

The multi-channel audio reproduction system can reproduce a two-channel audio signal. Using the speaker system 60, C
When reproducing the sound of a two-channel audio signal such as D, a front two-channel speaker 62,
64 and, in some cases, in addition thereto, sound is output only from the subwoofer speaker 72. In this case, the center speaker 66 and the rear speakers 68, 70
Does not output any sound. For example, when a 2-channel audio signal is reproduced using a 5.1-channel (L, R, C, SL, SR, LFE) audio reproduction system, two of the 5.1 channels (L, R) are used. ) Audio signal is output only from the system,
The remaining 3.1 channels (C, SL, SR, LFE) are not operating.

When listening to the sound of a multi-channel audio signal, for example, when listening to the sound of a 5.1-channel audio signal, if the output wattage per channel is 30 W, the output is 30 W × 6 channels. The wattage is 180 W in total, and it can be heard at a sufficient volume. On the other hand, when listening to the sound of a two-channel audio signal, the output wattage is 30 W × 2 channels and the total wattage is 60 W, and the volume that can be heard is low and the user often feels unsatisfactory for the reproduction of multi-channel audio. Become.

[0013]

As described above, in order to obtain a sufficient volume when listening to a two-channel audio, a larger output is required than during multi-channel reproduction. In order to solve this problem, it is conceivable to increase the output wattage of the two channels (L, R). For example, in the above example, the L and R channels are 50 W
× 2, C, SL, SR, LFE channels are 30W ×
There are four channels. However, in such an unbalanced output configuration in which a power amplifier having a large output is used only for the L and R channels, different parts and devices are required between the front channel and the rear channel. As a result, the circuit configuration becomes complicated and the power supply system becomes complicated, resulting in an increase in cost.

Further, since a higher load is applied to the front two-channel power amplifier compared to the power amplifiers of the other channels, the amount of heat generated by the power amplifier increases, and the front two-channel amplifier circuit is increased. Only a large heat sink is required. As a result, the space for installing the radiator plate becomes large as a whole, and there arises a problem that a larger space is required as compared with the conventional multi-channel audio reproduction system. The problem of space is that for small optical disc players,
This is a serious problem, and is also a very serious problem when the optical disk player is used as a portable type. Furthermore, depending on the specifications of components and devices, a high-output type may not be available, and it may be difficult to realize such a configuration.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-channel audio playback system which has a large volume and provides a sound effect with a sense of realism when a two-channel audio signal is reproduced in addition to a multi-channel audio signal. Is to provide a system.

[0016]

In order to achieve the above object, a multi-channel audio reproducing system according to the present invention comprises a D / A converter, a power amplifier, In a multi-channel audio reproduction system including a speaker and a speaker, a contact of a relay circuit is switched to connect a 2-channel speaker to a power amplifier of any channel different from the 2-channel system of the multi-channel. As described above, a relay circuit is provided between a power amplifier and a speaker, and when reproducing a two-channel audio signal, the L-channel speaker is amplified by the L-channel power amplifier and another channel power amplifier. Driven by the R channel speaker The signal processing and the relay circuit of the digital signal processing circuit are switched so that the BTL output mode is driven by the signal amplified by the power amplifier of the R channel and the power amplifier of another channel. And

In a multi-channel audio reproduction system, when reproducing a two-channel audio signal, power amplifiers of unused channels other than the two channels, for example, power amplifiers for rear speakers are not operating. Therefore, when detecting 2-channel audio reproduction, the power amplifier for the rear speaker that is not used is also used during 2-channel reproduction, and the front 2 (L,
By switching to the BTL output mode in which each of the R) channel speakers is driven using two power amplifiers, the maximum output volume at the time of two channel output can be increased. Here, BTL (Balanced Trans
former-Less) output means a method in which one speaker is driven by one set of two power amplifiers. This makes it possible to change a relatively small circuit of a multi-channel audio reproduction system that outputs a large volume even when reproducing a two-channel audio signal that requires a larger power than when reproducing a multi-channel audio signal. Can be realized by: INDUSTRIAL APPLICABILITY The present invention can be applied to any multi-channel audio reproduction system regardless of the application, and can be optimally applied to, for example, a 5.1-channel optical disk player.

[0018]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment 1 This embodiment is an example of an embodiment of a multi-channel audio reproduction system according to the present invention, and FIG. 1 shows a configuration of a main part of the multi-channel audio reproduction system of this embodiment. It is a block diagram. The multi-channel audio reproduction system according to the present embodiment is applied to the above-described optical disc player 20, and has a multi-channel signal output system, for example, a six-system signal output system, as described above. Although a system is provided, in the description of the main part of this embodiment, as shown in FIG. 1, two channels out of six channels are extracted and described.

As shown in FIG. 1, a signal processing circuit 10 provided in the multi-channel audio reproduction system according to the present embodiment includes a DSP (Digital Signal Processor).
1, a D / A conversion circuit 2, an amplifier A4, and a speaker A8 are provided for a channel A signal system output from the DSP 1, and a D / A conversion circuit 3, an amplifier B5, and a speaker AB9 are provided for a channel B signal system. Having. Here, the DSP 1 corresponds to the video / audio signal decoding block 42, the digital audio signal processing block 45, and the like in FIG.
The channel A signal system is one of the L and R channels of a 2-channel audio signal in the case of a 5.1-channel playback system, for example, L (left), the channel B system is one of C, SL, and SR. For example, it corresponds to an SL (rear left) signal system.

One of the input terminals of the speaker A8 is connected to the output terminal of the amplifier A4, and a relay circuit A6 is interposed between the other input terminal of the speaker A8 and the output terminal of the amplifier B5. The a contact of the relay circuit A6 is grounded, and the b contact is connected to the output terminal side of the amplifier B5. Further, a relay circuit B7 is interposed between the output terminal of the amplifier B5 and one of the input terminals of the speaker B9, and the other input terminal of the speaker B9 is grounded. The contact a of the relay circuit B7 is connected to the output terminal side of the amplifier B5,
The b contact is open.

Incidentally, in the optical disc reproduced by the optical disc player 20, information such as the type and type of the optical disc, the stream information of the audio signal, the number of reproduction channels, etc.
It is not possible to read all of the information recorded on the optical disc 31 just by observing the appearance of the optical disc 31. Therefore, usually, the RF signal obtained by irradiating the optical disc 31 with a laser is decoded by the RF signal processing block 39, and the obtained binary digital signal is analyzed to obtain such information.

This information is stored in the system control
It can be read by communicating with the RF signal processing block 39 and the video / audio decoding block 42 via the microcomputer 43. Such a series of information reading operations does not require any special signal processing, and is an operation normally performed. The read information is displayed on the operation display 55.

The signal processing circuit 10 of this embodiment automatically switches the relay circuits A6 and B7 based on the information of the optical disk thus obtained to reproduce a multi-channel audio signal, or Play the channel audio signal. A) At the time of reproducing a multi-channel audio signal Both the relay circuit A6 and the relay circuit B7 are switched to the a contact. As a result, the channel A system and the channel B system have the same configuration including the D / A converter, the amplifier, and the speaker. An L (left) channel signal is output from the channel A of the DSP 70.
The output signal is converted to an analog signal by the D / A converter 2, amplified by the amplifier A4, and output from the speaker A8.
Output from Since the relay circuit A6 is switched to the contact a, one of the input terminals of the speaker A8 is connected to the output terminal of the amplifier A4, and the other is connected to GND. Therefore, the speaker A8 is driven by the one-side input signal.

Similarly, an SL (rear left) channel signal is output from the channel B of the DSP 70. The output signal is converted into an analog signal by the D / A converter 3, amplified by the amplifier B5, and output from the speaker B9. Since the relay circuit B7 is switched to the contact a, one of the input terminals of the speaker B9 is an amplifier B
The other output terminal is connected to GND. Therefore, the speaker B9 is driven by the one-side input signal.

B) At the time of reproducing the two-channel audio signal At the time of reproducing the two-channel signal, the relay contacts of both the relay circuit A6 and the relay circuit B7 are switched to the contact b, and no audio output from the rear speaker B9 is generated.
An L (left) channel signal is output from channel A of the DSP 70. The output signal is converted into an analog signal by the D / A converter 2, amplified by the amplifier A4, and output to the speaker A8. On the other hand, from the channel B of the DSP 70, the L (left) channel signal is
The signal-L signal obtained by performing the phase inversion processing inside P is output. The output -L signal is converted into an analog signal by the D / A converter 3, amplified by the amplifier B5, and output. One of the input terminals of the speaker A8 has an amplifier A
4 is input. In addition, since the relay circuit A6 is switched to the contact b,
The output signal -L from the amplifier B5 is input to the other of the input terminals of the speaker A8.

As a result, the speaker A8 has L,-
The drive is performed by the so-called BTL connection driven by the L signal, and it is possible to generate a maximum output power about +6 dB larger than that at the time of the multi-channel connection without largely changing the basic circuit configuration. Further, since the relay circuit B7 is switched to the contact b, the input terminal of the speaker B is open and no audio signal is output.

As described above, by switching the relay circuit based on the audio signal information and switching the DSP signal processing, it is possible to obtain an optimum acoustic environment without making a large circuit change from the conventional circuit configuration. . In the above description, the reproduction of the audio signal of the L (left) channel of the two channels is taken as an example, but the reproduction of the audio signal of the R (right) channel is also described.
In the 5.1-channel audio reproduction system, for example, the SR (rear right) channel is used in the same manner as in the above-described example.

[0028] Modification This modification of the embodiment is a modification of the multi-channel audio playback system of an example embodiment, applying the front speakers and the rear speakers, the speaker integrated system as integrated Here is an example. In a speaker-integrated system, the same signal component is output from two speakers when a two-channel audio signal is reproduced.
For example, in the signal processing circuit 10 shown in FIG. 1, the L channel signal component is branched in the DSP 1, and the same signal is simultaneously output from the channels A and B of the DSP 1. The circuit configuration is the same as that in the state where the relay circuit A6 and the relay circuit B7 are switched to the a contact, as in the case of normal multi-channel reproduction. As a result, the L channel signal components are converted to the speakers A8 and B9.
Are output from the two speakers, and it sounds as if you are listening on a channel with a large sound output.

[0029]

According to the present invention, the contacts of the relay circuit are switched to connect the two-channel loudspeaker to the power amplifier of any one of the multi-channels other than the two-channel loudspeaker. , A relay circuit is provided between the power amplifier and the speaker to drive the L-channel speaker by the signal amplified by the L-channel power amplifier and the power amplifier of another channel when reproducing the 2-channel audio signal. By setting the R-channel speaker to the BTL output mode in which the R-channel speaker is driven by the signal amplified by the R-channel power amplifier and the power amplifier of another channel, the following effects are obtained. (1) A multi-channel amplifier system using a plurality of power amplifiers having a small maximum output power can output a larger volume than a conventional one even when listening to a two-channel audio signal such as music. (2) At the time of two-channel reproduction, one speaker can be driven by two power amplifiers, so that the heat radiation source can be divided into two. The heat sink can be made relatively small in the entire audio reproduction system, and the system can be downsized. Also, the cost can be kept low by using power amplifiers each having a small power. (3) Since the same performance amplifier can be used for both front and rear speakers, compared to a multi-channel audio playback system equipped with a power amplifier that supports high output only for two channels for front speakers, The sound quality is very close. (4) When realizing a multi-channel audio reproduction system having the same output power, a lower power supply voltage is required as compared with a case where BTL connection is not used. For this reason,
The voltage required by another circuit block inside the set can be generated from the same transformer winding, and a regulator IC using a smaller heat sink can be used for the power supply circuit, so the power supply circuit of the set can be simplified Can be structured.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a main part of a multi-channel audio reproduction system according to an embodiment.

FIG. 2 is a block diagram showing a configuration of an optical disk player.

FIG. 3 is a block diagram illustrating a configuration of a signal detection unit and a signal processing and control unit.

FIG. 4 is a block diagram illustrating a configuration of a D / A conversion and amplification unit and an output unit.

FIG. 5 is a perspective view showing a speaker system of an output unit.

[Explanation of symbols]

1 ... Digital Signal Processor (DSP), 2, 3 ...
... D / A conversion circuit, A4, B5 ... Amplifier, A6, B7
…… Relay circuit, A8, B9 …… Speaker, 10 ……
Signal processing circuit provided in the multi-channel audio reproduction system of the embodiment, 20... Optical disc player, 22... Signal detection unit, 24... Signal processing and control unit, 26... D / A conversion and amplifier Unit, 28 output unit, 31 optical disk, 33 spindle motor,
34 optical pickup, 35 threading motor, 36 RF / EQ amplifier, 38 motor driver, 39 RF signal processing block, 40 servo block, 41 D-RAM, 42 Video / audio signal decoding block, 43: microcomputer for system control, 44: interface microcomputer, 45: digital audio signal processing block, 46: D / A conversion block for audio signal, 47
... D / A conversion block for video signal, 48... Three audio signal amplifier blocks, 49... Multiple full-range speakers, 50... Low-frequency dedicated speaker, 51... Video output device, 52. Signal attenuation block (VO
L), 53 ... relay circuit, 54 ... operation button, 55
…… Operation indicator.

Claims (3)

[Claims] 1. A multi-channel audio reproducing system comprising a D / A converter, a power amplifier, and a speaker for each output channel of a digital signal processing circuit. A relay circuit is provided between the power amplifier and the speaker so that the speaker is connected to the power amplifier of any channel different from the two-channel system of the multi-channel system, and the two-channel audio signal is reproduced. At this time, the L channel speaker is driven by the signal amplified by the L channel power amplifier and the power amplifier of another channel, and the R channel speaker is driven by the R channel power amplifier and the power of another channel. The signal amplified by the amplifier To be driven BTL output mode, a multi-channel audio reproduction system is characterized in that so as to switch the signal processing and the relay circuit of the digital signal processing circuit. 2. The multi-channel audio reproduction system according to claim 1, wherein the multi-channel audio reproduction system is a 5.1-channel audio reproduction system. 3. A multi-channel audio signal or a two-channel audio signal is reproduced by automatically switching a relay circuit based on information recorded on an optical disk. 2. The multi-channel audio reproduction system according to claim 1, wherein: