JP2000102100A - Surrounding circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit capable of obtaining pseudo sound from the rear part of a listener by a front speaker by an analog circuit. SOLUTION: Reflected sound and reverberation sound from the rear part of the listener are generated in a pseudo stereo circuit 12 based on left and right audio input signals L and R and stereo pseudo signals are attenuated, then added to the left and right input audio signals and impressed to speakers 5 and 6. Thus, a sound field capable of obtaining the pseudo sound from the rear part of the listener from the front speaker is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surround circuit for generating a surround effect using only two speakers.

[0002]

2. Description of the Related Art Heretofore, when watching a movie at home, two speakers are arranged before and after a listener,
Furthermore, by arranging the center speaker between the front left and right speakers, it was possible to enjoy the surround effect of being in a movie theater while staying at home. In recent years, DSP
(Digital signal processor),
The surround effect can be obtained only with the front left and right speakers without using five speakers as described above. Figure 3 shows a surround circuit using a conventional DSP.
Shown in

In FIG. 3, left and right stereo signals L and R
And the surround signal S are input. The surround signal S is a signal for generating reflected sound and reverberant sound when the left and right stereo signals L and R are reflected or reverberated in a room such as a movie theater. From the surround signal S, a stereo circuit 1 outputs stereo signals L1 and R1.
Is generated by digital signal processing and applied to the adders 2 and 3 respectively. The stereo signals L1 and R1 are signals for generating reflected sound and reverberant sound. Also, the stereo signals L1 and R1 are input to the DSP 4,
After being converted into a digital signal in P4, signal processing for forming a sound field is performed so that sound from the front of the viewer can be heard from the front speaker, the signal processing is returned to an analog audio signal, and the output signals LS1 and RS1 are added. Applied to circuits 2 and 3, respectively.

In the adder circuit 2, the left stereo signal L,
The stereo signal LS1 and the signal RS1 are added, the added signal is applied to the left speaker 5, and the addition circuit 3 outputs the right stereo signal R, the stereo signal R1, and the signal LS.
Are added, and the added signal is applied to the right speaker 6. Therefore, a surround effect is formed by the left and right speakers 5 and 6 in addition to the left and right stereo sounds, the reverberation sound, the reflected sound, and the sound heard from behind the listener.

[0005]

However, the conventional circuit has a disadvantage that the reverberation sound, reverberation sound, and sound from the rear are all generated by digital signal processing, so that the circuit becomes complicated and expensive. is there. In addition, since the above-described reverberation sound and the like are generated based on the surround signal S, there is a disadvantage that a surround effect cannot be obtained in an acoustic system having no surround signal.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a surround circuit for generating a surround effect by two speakers installed in front of a listener, and to a listener based on left and right audio input signals. Pseudo-stereo circuit for generating left and right stereo pseudo signals to form reverberation sound and reflection sound from the rear, and first and second addition circuits for respectively adding the left and right pseudo stereo signals and the left and right audio input signals of the pseudo stereo circuit And characterized in that:

In particular, the pseudo stereo circuit includes a delay circuit for delaying a sum signal or a difference signal of the left and right audio signals, a first attenuation circuit for attenuating the sum signal or the difference signal, an output signal of the delay circuit, and the attenuation signal. A third addition circuit that adds an inverted signal of the output of the circuit, a fourth addition circuit that adds the output signal of the delay circuit and the output signal of the attenuation circuit,
Characterized by comprising:

[0008] A second attenuation circuit is provided for attenuating an output signal of the pseudo stereo circuit and outputting the signal to the first and second addition circuits.

According to the present invention, a left and right stereo pseudo signal for forming a reflected sound or a reverberant sound is generated from a left and right audio input signal, and the left and right pseudo stereo signals are added to the input audio signal and then emitted from a speaker. This makes it possible to form a sound field in which sound is sounding from behind the listener using two speakers.

[0010]

FIG. 1 is a diagram showing an embodiment of the present invention. Reference numeral 10 denotes a pseudo-stereo circuit that generates stereo pseudo signals LS and RS based on left and right audio input signals L and R, and 11 denotes a stereo pseudo circuit. An attenuation circuit for attenuating the signals LS and RS, respectively, 12 is a left audio input signal L
And an adder 13 for adding the attenuated surround signal LS and the attenuated surround signal RS.

In FIG. 1, the left and right audio input signals L
And R are calculated by the pseudo stereo circuit 10 into the left and right stereo pseudo signals LS and RS so that the listener can hear the sound spread like a stereo. The surround signals LS and RS from the pseudo stereo circuit 10 are respectively attenuated by the attenuator 11 and then added to the adders 12 and 13.
Are added to the left and right audio input signals, respectively. According to the output signals of the adders 12 and 13, the speakers 5 and 6
Is driven, and a sound having a surround effect is generated for a listener. In particular, the listener can hear the sound spread to the rear from the speakers 5 and 6 arranged in the front.

FIG. 2 is a diagram showing a specific circuit of the pseudo-stereo circuit 10. Reference numeral 20 denotes left and right audio input signals L and R.
, And 21 is a left and right audio input signal L.
And R are subtracted circuits, and 22 and 23 are addition circuits 2
First and second selection circuits for selecting 0 or the output signal of the subtraction circuit 21; 24, a delay circuit for delaying the output signal of the first selection circuit 22; 25, attenuation for attenuating the output signal level of the second selection circuit 23 Circuit, an inverter for inverting the output signal of the attenuation circuit 25; 27, an addition circuit for adding the output signal of the delay circuit 24 and the output signal of the inverter 26;
Reference numeral 8 denotes an addition circuit that adds the output signal of the delay circuit 24 and the output signal of the attenuation circuit 25.

In the adding circuit 20 shown in FIG. 2, the left and right audio signals L and R are added to generate a signal (L + R). Further, in the subtraction circuit 21, the left and right audio signals L and R are subtracted to generate a signal (LR). One of the signal (L + R) or the signal (LR) is the first
After being selected by the second selection circuits 22 and 23, the output signal of the first selection circuit 22 is delayed by a predetermined time by the delay circuit 24, and the output signal of the second selection circuit 23 is attenuated by the attenuation circuit 25. You.

Then, in addition circuits 27 and 28,
Using the output signal of the delay circuit 24 as the main signal, the attenuated signal (L + R) or (LR) and its inverted signal are added to the main signal. As a result of the addition, left and right stereo pseudo signals LS and RS are obtained. Here, in order to understand the operation, it is assumed that rear speakers that are not originally arranged are arranged, and the left and right stereo pseudo signals LS and RS are applied to the rear speakers. Since the main signal is a signal obtained by delaying the left and right audio input signals, the same sound is emitted from the rear speaker after the sound is emitted from the front speaker. Therefore, the reflected sound from behind the listener can be reproduced from the left and right audio input signals. Also,
Since the output signal of the attenuation circuit 25 and its inverted signal are added to the output signal of the delay circuit 24, the same sound is prevented from being generated from the rear left and right speakers.
The levels and phases of the output signals of the adders 27 and 28 change differently. As a result, sound from the rear speakers can be prevented from being localized between the rear speakers. As described above, the circuit shown in FIG. 2 can reproduce the reverberation sound from behind the listener, and can form the sound field behind the listener by reproducing the reflected sound and the reverberation sound. Therefore, the circuit of FIG. 2 can generate a stereo pseudo signal that can reproduce the sound from behind the listener in a pseudo manner from the left and right audio input signals.

When the same signal is generated by the same signal from the speakers 5 and 6, the sound is localized in the middle of the speakers 5 and 6. Here, since the stereo pseudo signals LS and RS are not the same signal, the sound is not localized between the speakers 5 and 6 by the surround signal. Therefore, there is a difference between the left and right stereo pseudo signals LS and RS in the time to reach the listener from the left and right speakers 5 and 6, respectively, whereby the stereo pseudo signals LS and RS are variously reflected behind. I will be. By applying such stereo pseudo signals LS and RS to the front speakers 5 and 6, it is possible to form a sound field that generates sound from behind the speakers 5 and 6.

Further, since the stereo pseudo signals LS and RS are attenuated and applied to the addition circuits 12 and 13,
The reflected sound from behind the listener can be reproduced more effectively.

[0017]

According to the present invention, a stereo pseudo signal for generating a sound from behind a listener is generated from an input audio signal, and further, the input audio signal is added,
Since the surround effect by the two speakers is obtained, the circuit configuration can be simplified. Therefore, an analog circuit or a Bi-CMOS circuit can be configured without using a DSP.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a circuit example showing a specific circuit of the pseudo stereo circuit 10 of FIG.

FIG. 3 is a block diagram showing a conventional example.

[Explanation of symbols]

 Reference Signs List 10 pseudo stereo circuit 11 attenuating circuit 22, 23 selecting circuit 25 attenuating circuit 26 inverter

Continued on the front page (72) Inventor Naohiro Iida 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. F-term (reference) 5D062 BB13 BB14

Claims (3)

[Claims] 1. A surround circuit for generating a surround effect by two speakers installed in front of a listener, wherein a reverberation sound or reflection from a rear side to a listener based on left and right audio input signals. A pseudo stereo circuit for generating left and right stereo pseudo signals for forming a sound, and first and second addition circuits for respectively adding the left and right pseudo stereo signals and the left and right audio input signals of the pseudo stereo circuit. Surround circuit. 2. A pseudo-stereo circuit, comprising: a delay circuit for delaying a sum signal or a difference signal between left and right audio signals; a first attenuation circuit for attenuating the sum signal or the difference signal; an output signal of the delay circuit and the attenuation; 2. The circuit according to claim 1, further comprising: a third addition circuit that adds an inverted signal of a circuit output; and a fourth addition circuit that adds an output signal of the delay circuit and an output signal of the attenuation circuit. Surround circuit. 3. The surround circuit according to claim 1, further comprising a second attenuation circuit that attenuates an output signal of the pseudo stereo circuit and outputs the signal to the first and second addition circuits.