JPH03195200A - Surround stereo reproducing device - Google Patents

Abstract

PURPOSE:To obtain a stable image orienting and extending feeling without inverting the balance of right and left signals by providing the amplitude correcting operation of a synthesized signal while coupling the differential signals of two systems, which amplitudes and phases are respectively different, for the right and left differential signal to apply the extending feeling. CONSTITUTION:A first amplifier 2 and a phase shifter 3 are provided to divide L-R and to set one level k1 and a phase phi for the differential signal between respective right and left channel source signals, and a second amplifier 4 is provided to set another level k2. A second adder 7 is provided to add the output of a first adder 5 and the L and to define an added result as a driving signal LM of a main left channel, and the second adder 7 is provided also to add the output of a phase inverter 6, which inverts the output phase of the adder 5, and the R and to define an added result as a driving signal RM of a main right channel. Thus, a condition to invert the balance is prevented from being generated in the middle of stereo reproducing, and the image orienting and extending feelings, etc., can be made stable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sound field reproducing circuit for a surround stereo reproducing apparatus that emphasizes not only an excellent sense of spaciousness but also left and right balance.

[Prior Art] In surround stereo, the signal format that creates a sense of spaciousness is generally a method in which the signals of opposite channels are subtracted and mixed at a certain ratio of levels. It is obtained by applying level and phase correction processing to . An example of its configuration can be expressed mathematically as follows: LM=L+k (LR) ・φ・・・・・・・・・
...... (+1RM=R-k (L-R) ・
φ・・・・・・・・・・・・・・・ (2) Lr=+k
(L-R) ・φ ・・・・・・・・・・・・・・・
・ (3) Rr--k (L-R) ・φ ・・・・
・・・・・・・・・・・・ (4) However, LM・・・・・・
・・・・・・Left main channel signal RM・・・・・・・
・・・・・・Right main channel signal L・・・・・・・・・・・・
...Left channel original signal R...
... Right channel original signal (L-R) ... Difference signal between left and famous current signal Lr ...... Left rear channel signal Rr ......・・・・・・Right rear channel signal k・・・・・・・・・・・・・・・(L-
R) setting level φ・・・・・・・・・・・・・・・(
LR) phase transition.

In the above, the values of k and φ are set to a state that is judged to have the best surround effect, and specifically, the values of k and φ are set to the state where the surround effect is judged to be the best. is provided by an amplifier and a phase shifter.

[Problem to be Solved] The operation and problems of the conventional system expressed by the above equations (1) to (4) will be explained using the vector diagram shown in FIG. 3 and using the same symbols as in the embodiment. At a certain point in Figure 5, IR
For the original signal of the left famous channel where I>ILI and the phase difference is φ1, the second term k (L−R) in equations (1) and (2) ・φ is the right channel original signal R and ±1
Considering a phase difference of 80°, k (L-R)
−φ=−X−R (where x>0)・・・・・・・・・・・・
・・・・・・・・・・・・・・・ (5), ', LM=
L-X-R・・・・・・・・・・・・・・・・・・
... (6)RM= (1+X)・R...light...
Shouting...(7), and in the original signal, originally R1>ILI, old, group... old...
・(8) was, as shown in Figure 5, IRMI<ILMI...dan...river...
(9), a situation in which the balance is reversed occurs at any time during stereo playback, and the sound image localization, sense of spaciousness, etc. become unstable, which is a problem that needs to be solved.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional example by improving the processing of left and right difference signals that produce a sense of spaciousness.

[Means for Solving the Problems] A surround stereo reproduction device according to the present invention for achieving the above object will be explained using FIG. 1 showing the configuration of an embodiment. L1 is the right channel original signal, R1 is the difference signal between the left and right channel original signals (L-R), LM is the left main channel drive signal,
Assuming that the right main channel drive signal is RM, the left rear channel drive signal is Lr, and the right rear channel drive signal is Rr, a subtracter (1) obtains (LR) from L and R;
Divide the (L-R) and set the level kl of one (L-R)
a first amplifier (2) and a phase shifter (3) that set the phase φ and a second amplifier (4) that sets the level of the other divided (L-R) to 2; a first adder (5) that adds the output of the second amplifier (4) and the output of the first amplifier (2) and the phase shifter (3); a second adder (7) that adds the above signals to produce a left main channel drive signal LM, and a phase inverter that inverts the output phase of the adder (5) to produce a right rear channel drive signal Rr. (6), and a second adder (7) that adds the output of the phase inverter (6) and the R to generate the right main channel drive signal RM, and the L
M, RMSLr, and Rr are respectively the following vector expressions: % expression %() (10) () (11) L r=+kl (L-R) '2(L-R) for φ+
・・・・・・・・・・・・・・・・・・ (12)R
r=-kl (L-R) ・2(L-R) to φ-...
This is a surround stereo playback device characterized by a signal given by (13).

[Operation] The operation of the surround stereo playback device having such a configuration can be explained by referring to the vector diagram shown in FIG. Considering the case where has a phase difference of ±180° from the right channel original signal R, kl (L-R) -φ=-X-R (where x〉0)
・・・・・・・・・・・・・・・・・・(14) Referring to equations (6) and (7) of the conventional example, LM= (L-X-R
)+2 (L-R)...(15)RM= [(1+
X) ・R] - becomes 2 (L-R)...(16), and as is clear from Figure 2, the phase changes for the left and right original signals, but the mutual levels do not reverse. .

Also, for simplicity, when the R and L signals have a mutual phase difference of 0 and only a level difference, that is, for a certain value M, L=M...・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・(17
)R=Y-M・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・(I8)(Q
<Y<1), in the case of the conventional example, the second term k of equation (11, (2))
(L-R) ・φ is ±18 with the right channel original signal R
When the phase difference is 0'', and K=1, LM=M
-(1-Y) ・M=YM ... (I9)RM
=YM+ (1-Y) ・M=M... (20
), which causes a reversal of the mutual balance between the channels, but in the case of the present invention, (+01. The second term kl (L-R) in equation (11) ・φ is ± the right channel original signal R.
When there is a phase difference of 180°, k1=1, k2=1/
2, then LM=M-(1-Y)M+ (1-y)M/2= (1
+y) M/2 ・・・・・・・・・・・・・・・
... (21)RM=YM+ (1,-Y)M-(1-
Y) M/2 (1+y) M/2 ・・・・・・・・・
・Old・Seal・ (22), and both are equal. In this case, k2=1/2 is the threshold for balance reversal, and k2
>1/2, it is possible to prevent balance reversal.

Embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2.
FIG. 1 is a diagram illustrating the configuration and signal flow of an embodiment of the present invention, in which a and b are left and right input terminals, respectively, and the branched signal paths are connected to a subtracter 1. Input terminal a
, a part of the R signal and the R signal applied to the subtracter 1 become the left and right difference signals, that is, the (L-R) signal, and the output (L-R) signal of the subtracter 1 is The first amplifier 2 sets the level to kl, and then the phase shifter 3 receives the phase correction φ, and the second half is set to the level kl by the first amplifier 2.
-R) ・It becomes the φ signal.

The other (L-R) signal of the two halves is sent to the second amplifier 4.
The level is set to 2, resulting in a 2 (LR) signal.

This kl (L-R) ・φ signal and the 2 (L-R) signal are applied to the first adder 5 and become the 2 (L-R) signal at kl (L-R)φ10, and the corresponding A part of the kl (L-R)・φ102(1,-R) signal is sent to the left rear channel output terminal 9 as the left rear channel drive signal Lr.
It reaches L+. On the other hand, kl (L-R) ・φ+ has 2 (
A part of the L-R) signal is applied to the second adder 7, where it is added to the L signal from the input terminal a, resulting in L+kl (L-R)
- φ1 becomes the 2 (L-R) signal, that is, the left main channel drive signal LM, and reaches the left main channel output terminal 91M.

In addition, a part of the kl (L-R) · φ102 (L-R) signal is reversed in phase by the phase inverter 6 and kl
(L-R) ・2 (L-R) signal becomes φ-, and the corresponding -
A part of the kl (L-R) and φ-2 (L-R) signals then reaches the right rear channel output terminal 9Rr as the right rear channel drive signal Rr.

A part of the 2 (L-R) signal is applied to the second adder 8, and the R from the input terminal is applied to the second adder 8.
Added to signal R-kl (L-R) ・2 to φ-
(LR) signal, that is, the drive signal RM of the right main channel, and reaches the output terminal 9RM of the right main channel. In this embodiment, they are kl-0~1 (variable) and k21/2 (fixed).

Subtractor 1, first amplifier 2, phase shifter 3 of the above embodiment
, the second amplifier 4, the first adder 5, the phase inverter 6, the second adder 7, the third adder 8, etc. are conventionally used devices or circuit blocks with the same function. ing.

In addition, the respective output terminals 9LM, 9RM, 9Lr, of the left and right main channels and the left and right rear channels,
A power amplifier (10) and a speaker (11) of each channel are connected to 9R+.

The optimal values of the coefficients kl and k2 for left-right difference signal processing in the present invention vary depending on the listening source, speaker installation status, listener's preference, etc., but if the difference signal level is too high compared to the original signal level, Since the difference signal enters each channel in reverse phase, a feeling of reverse phase is felt and gives an unfavorable result, so it is considered desirable to suppress both kl and k2 to 1 or less. Therefore, it seems appropriate for the ranges of kl and k2 to be 0≦kl≦1, 1/2≦, and 2≦1, taking into consideration the above-mentioned threshold value at which the balance reversal does not occur.

Above, the surround stereo playback device according to the present invention has been described in detail based on embodiments that are considered to be representative, but the embodiments of the playback device according to the present invention are not limited to the structure of the above embodiments, and are as described above. As long as the invention has the constituent elements described in the claims, exhibits the functions of the present invention, and has the effects described below, it may be implemented with appropriate modifications.

[Effects] The surround stereo playback device according to the present invention has the effect of correcting the amplitude of the composite signal by combining the left and right difference signals that give a sense of spaciousness with two systems of difference signals having different amplitudes and phases. This has the effect that no matter what amplitude and phase relationship the left and right original signals have with each other, the balance of the left and right signals is not reversed, and stable sound image localization and a sense of spaciousness can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the configuration of an embodiment of the present invention, FIG. 2 is a vector diagram for explaining the operation of the same embodiment, and FIG. 3 is a vector diagram for explaining the operation of the conventional example. 1 is a subtracter, 2 is a first amplifier, 3 is a phase shifter, 4 is a second amplifier, 5 is a first adder, 6 is a phase inverter, 7
is the second adder, and 8 is the third adder.

Claims (1)

[Claims] 1. Left channel original signal is L, right channel original signal is R
, the difference signal between the original signals of the left and right channels (L-R), the left main channel drive signal LM, the right main channel drive signal RM, the left rear channel drive signal Lr, the right rear channel drive signal If Rr, then from L and R (L
-R), and a first amplifier (2) and phase for dividing the (L-R) and setting the level k1 and phase φ of one (L-R). A shifter (3), a second amplifier (4) that sets the level k2 of the other divided (L-R), and an output of the second amplifier (4) and the first amplifier (2). ) and the output of the phase shifter (3) to obtain the left rear channel drive signal Lr; A second adder (
7), a phase inverter (6) that inverts the output phase of the adder (5) to obtain a right rear channel drive signal Rr, and adds the output of the phase inverter (6) and the R. A third adder (8) receives the right main channel drive signal RM, and the LM, RM, Lr, and Rr each have the following vector formula: LM=L+k1(L-R)・φ+k2(L-R) RM=
R-k1 (L-R)・φ-k2 (L-R) Lr=+k1
(LR)・φ+k2(LR)Rr=-k1(LR
)・φ−k2(L−R). 2. The surround stereo reproduction apparatus according to claim 1, wherein the first amplifier (2) and the phase shifter (3) are combined into a common integrated device.