JPH01247000A - Digital sound reproducing device - Google Patents

Abstract

PURPOSE:To secure the quality of sound signals after D/A conversion by selectively supplying either one of aperture signals for L and R to each sound reproducing circuit. CONSTITUTION:The audio signals SA having L- and R-channel signals of the output ot a D/A converter are supplied to sound reproducing circuits 10 and 20 of two systems and the L- or R-channel signals are processed by means of aperture signals for L APTL or R APTL. Each aperture signal is supplied to each circuit 10 and 20 through a switching circuit 50. The kind of the aperture signals supplied to the circuits 10 and 20 and the mode of the sounds outputted from terminals 41 and 43 are switched depending upon the states of signals SQ1 and SQ2 formed through the operation of the mode switching switch of an audio apparatus.

Description

Detailed Description of the Invention (Industrial Application Field) This invention converts digital audio on a compact disc (hereinafter referred to as CD), a laser vision disc (hereinafter referred to as LD), a CD video (hereinafter referred to as CDV), etc. into an analog audio signal. It relates to a device that reproduces analog audio signals for the L or R channels independently or inverted and outputs them to the audio output terminals for the L channel or R channel. The present invention relates to a digital audio reproducing device that can simultaneously output audio signals without causing deterioration of audio signals.

(Prior art) In audio equipment such as CD, LD, or CDV, when handling audio multiplexing, bilingual audio, etc., the audio output terminal is set for the L channel or the R channel, and the audio signal of the day channel is output. It is possible to output the audio signals independently (referred to as STEREO mode) or inverted and independently (referred to as REVER3E mode), or output only one audio signal at the same time (referred to as L-MONO or R, MONO). (hereinafter, for convenience of explanation, it may be referred to as an output mode switching function).

FIG. 2 is a circuit diagram schematically showing a conventional digital audio playback device for realizing such an output mode switching function. In addition, such reproduction equipment, GO, LDX
It is provided after the D/A converter at the output stage of audio equipment such as CDV.

The conventional digital audio playback device shown in FIG.
This is a two-system audio reproduction circuit into which the audio signal (indicated by SA in the figure) carrying the A converter and the day channel signal in a time-division manner is respectively input, and each inputs an L aperture signal. A first audio reproducing circuit indicated by 10 and a second audio reproducing circuit indicated at 20 process either signal of the L or R channels by PTL or daily aperture signal ^PTR. It is growing.

In general, this device includes an audio signal switching circuit 30 for switching the output mode of the reproduced audio signal. A first output terminal 41 and a second output terminal 43 are provided at the subsequent stage of this audio signal switching circuit 30, respectively.
Audio signals in designated modes are output from these terminals.

The first and second audio reproduction circuits 10 and 20 have the same configuration. Taking the example of the first audio reproduction circuit +ot, its configuration will be described. This includes a sample hold circuit indicated by 11, a de-emphasis circuit indicated by 13, and a low pass filter indicated by 15.

Ila provided in the sample and hold circuit 11 is an analog switch IC, with Z terminal being a neutral contact and Z being a negative or secondary side contact. Each terminal has a terminal, a Z terminal, and a terminal. In this case, the terminal indicated by Zo is connected to the ground, and the terminal indicated by Zl is connected to the operational amplifier indicated by Ilb. This analog switch Ila
is between the ZZo terminals or between the 2-
Z and the terminals become conductive. The terminal shown with 2 is D/A.
The above-mentioned audio signal SA from the converter is input.

The second audio reproduction circuit 20 also includes a sample hold circuit indicated by 21, a de-emphasis circuit indicated by 23, and a de-emphasis circuit indicated by 25.
It is equipped with a low-pass filter shown in , and each component is connected in the same manner as in the first audio reproduction circuit 10 .

FIGS. 3A and 3B are signal waveform diagrams for explaining the L and daily aperture signals APTL and ^PTR, which are signals for switching the analog switches of the sample and hold circuit. These signals are signals that are synchronized with the system clock of the audio device, and are synchronized with the audio signal output from the D/A converter or carrying the R channel signal. Then, when the aperture signal is "]", the corresponding sample hold circuit samples the audio signal SAt, and the aperture signal is "0".
”, the audio signal will be halted. Therefore, for example, if the first audio reproducing circuit 10t is considered as an R channel audio signal reproducing circuit, the R channel audio signal is reproduced by supplying the everyday aperture signal APTR to the switching signal terminal of the analog switch Ila.

L to the analog switch 2+a of the second audio playback circuit 20
The L channel audio signal is reproduced by supplying the aperture signal APTL. The analog audio signal reproduced as described above is then output to the audio signal switching circuit 30.

This audio signal switching circuit 30 is generally composed of a relay or an analog multiplexer, etc.The audio switching circuit 30 converts the audio signal supplied thereto into a switching signal from a microcomputer provided in the audio equipment. Desired mode specified by Sc etc. (5TEREO, REV
ERSE, etc.) and output terminals 41 and 4.
Output from 3.

(Problems to be Solved by the Invention) However, in the digital audio playback device shown in FIG. 2, an audio signal switching circuit is provided at a stage subsequent to the audio playback circuit. Therefore, when a relay is used in an audio switching circuit, there is a problem in that the aging of the contacts of the relay directly affects the audio, resulting in deterioration of the audio signal. Furthermore, when an IC such as an analog multiplexer is used, there is a problem in that the performance of the IC is poor, so that the distortion rate of the audio signal 6 deteriorates just by passing it through the IC.

This invention was made in view of these points,
Therefore, it is an object of the present invention to output the audio signals of the L Father's Day channel independently or inverted and independently to the audio output terminals for the L channel and the Japanese channel, or to output only one audio signal at the same time. An object of the present invention is to provide a digital audio reproducing device M that can perform this without causing deterioration of the audio signal.

(Means for Solving the Problem) In order to achieve this objective, according to the present invention, D/A
There are two audio reproduction circuits into which the audio signals output from the converter and carrying the day channel signals are input, respectively, and each of the circuits receives the audio signals of the aforementioned channels by the L or day aperture signal. A digital audio playback device comprising an audio playback circuit that processes any one of the above signals, further comprising a switching circuit that selectively supplies one of the above-mentioned L and daily aperture signals to each of the above-mentioned sound playback circuits. It is characterized by the following.

(Function) According to such a configuration, ■... L aperture signals are supplied to both audio reproduction circuits, ■...
Supplying the R aperture signal to both audio reproduction circuits; 1) Supplying the L aperture signal to one audio reproduction circuit, and supplying the R aperture signal to the other audio reproduction circuit; (1) It is possible to select either to supply an R aperture signal to one audio reproduction circuit and to supply an L aperture signal to the other audio reproduction circuit; As a result, at the input stage to the audio reproduction circuit, that is, before the audio signal from the D/A converter is converted into an analog audio signal, 5TEREO,
REVER3E, switching to L-MONO or R-MONO can now be performed.

(Example) Hereinafter, an example of the present invention will be described using an example in which the present invention is applied to the digital audio playback device shown in FIG.

FIG. 1 is a block diagram showing a Digimol audio playback device according to an embodiment. It should be noted that this figure is only a schematic representation to the extent that the present invention can be understood, and therefore, it is understood that the dimensions, shapes, layout, etc. of each component are not limited to the illustrated example. sea bream. Further, in FIG. 1, the same components as those shown in FIG. 2 are denoted by the same reference numerals.

The digital audio playback device of the embodiment shown in FIG.
This is a two-system audio reproduction circuit into which audio signals (indicated by SA in the figure) carrying the signals of the left and right channels outputted from the /A converter are respectively input, and each of the
daily aperture signal APL or daily aperture signal APT
a first audio reproduction circuit indicated by 10, which processes either the L or R channel signal by R;
and a second audio reproduction circuit shown in FIG.

The -th and second audio reproduction circuits +0.20 have the same configuration. Taking the first audio reproduction circuit 10 as an example, its configuration will be described. This includes a sample hold circuit indicated by 11, a de-emphasis circuit indicated by 13, and a low pass filter indicated by 15. The output of the low-pass filter 15 is connected to the first audio output terminal 41. An audio signal SA from a D/A converter is input to a terminal indicated by 2 of an analog switch indicated by 11a provided in the sample and hold circuit 11. Also, 20 of the analog switch Ila
The terminal indicated by is connected to ground, and the terminal indicated by Zl is connected to an operational amplifier indicated by Ilb. The second audio reproduction circuit 20 corresponds to the components of the first audio reproduction circuit.
It includes an analog switch 21a, an amplifier 21b, a sample hold circuit 21 composed of a resistor and a capacitor, a de-emphasis circuit 23, and a low-pass filter 25. The output of the low-pass filter 25 is connected to the second audio output terminal 43.

The first audio reproduction circuit 10 and the second audio reproduction circuit 20 as described above are, as already explained using FIG.
The reproduction of the audio signal of either channel is carried out using a conventional aperture signal, and the apparatus of the present invention includes a circuit as described below for supplying the aperture signal. There is.

That is, it includes a switching circuit that selectively supplies either the above-mentioned signal or the daily aperture signal to the first audio circuit 10 and the second audio reproduction circuit 20, and the aperture signal is transmitted through this switching circuit. The signal is supplied to each audio reproduction circuit 10.20 via the audio signal.

In FIG. 1, 50 indicates this aperture signal switching circuit.The aperture signal switching circuit 50 of this embodiment is as follows:
This example includes a first analog switch shown at 51 and a second analog switch shown at 53. These analog switches 5L53 can be configured with the same analog switch Ila as described above.

The neutral terminal of the analog switch 51 indicated by X is connected to the switching terminal of the analog switch Ila of the first audio reproduction circuit 10. Y of analog switch 53
The neutral point terminal indicated by is connected to the switching terminal of the analog switch 21a of the second audio reproduction circuit 20.

Also, the X of the first analog switch 51. The terminal indicated by Y and the terminal indicated by Y of the second analog switch 53 are connected to L.
A signal line 55a to which an aperture signal APR is supplied is commonly connected. Roughly, the X of the first analog switch 51.

Y of the terminal and second analog switch 53 indicated by .

A signal line 55b to which a daily aperture signal APTR is supplied is commonly connected to the terminal shown in FIG. Further, the switching terminal of the first analog switch 51 has a signal line 57a for a mode switching signal indicated by SQ, and the switching terminal of the second analog switch 53 has a signal line 57a indicated by SQ2.
Signal lines 57b for mode switching signals shown by are connected to each other.

In addition, SQ and S Q 2 are, for example, installed in audio equipment, 5TERO, REVERSE, L-MONO.
, R-MONO changeover switch, or a signal supplied as necessary from a control circuit such as a microcomputer in an audio device or from an external snowmaker. In the apparatus shown in FIG. 1, the type of aperture signal supplied to the first and second audio reproduction circuits 10.20 and the output from the audio output terminal 41.43 are determined depending on the signal states of these signals SQI and SQ2. The output audio mode changes as shown in Table 1. still,
In Table 1, the 1st and 2nd audio reproduction circuits are abbreviated as 2nd and 2nd, respectively.

Table 1 Note that the present invention is not limited to the above-described embodiments. The configurations of the audio reproduction circuit and the aperture signal switching circuit are not limited to those of the embodiments, and may have similar functions. It is obvious that other configurations may also be used.

(Effects of the Invention) As is clear from the above explanation, according to the digital audio playback device of the present invention, D/A conversion is performed at the input stage to the audio playback circuit, that is, when considering a digital audio playback such as a CD. Supply of aperture signal at the time of sampling before the audio signal from the device is converted to an analog audio signal.
EO, REVERSE, L-MONO or R-MON
Therefore, even if the audio reproduction bag is equipped with a circuit that has a mode switching function, the audio signal after sample and hold does not go through a relay or analog switch, so the audio Signal quality is less likely to be compromised.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing a digital audio playback device according to an embodiment, FIG. 2 is a block diagram schematically showing a conventional digital audio playback device M+, and FIGS. 3(A) and (8) are FIG. 2 is a diagram used to explain the conventional art and the present invention, and is a diagram used to explain L and R aperture signals. 10... First audio reproduction circuit 11... Sample hold circuit 11a... Analog switch, Nb-... Operational amplifier 13... De-emphasis circuit 15... Low pass filter 20... Second audio Reproduction circuit 21... Sample hold circuit 21a... Analog switch, 21b... Operational amplifier 23... De-emphasis circuit 25... Low pass filter 41... First audio output terminal 43... First Audio output terminal 50...Aperture signal switching circuit 51...First analog switch 53...First analog switch 55a, 55b, 57a, 57b - Signal line.

Claims (1)

[Claims] (1) A two-system audio reproduction circuit into which audio signals output from a D/A converter and carrying L and R channel signals are respectively input, and each channel is controlled by an L or R aperture signal. A digital audio playback device comprising an audio playback circuit that processes any one of the above signals, the switch for selectively supplying any one of the above and R aperture signals to each of the audio playback circuits. A digital audio playback device characterized by comprising a circuit.