JPH04127700A - Image controller - Google Patents

Abstract

PURPOSE:To control the sense of a distance as well together with the sense of a direction by controlling the extending time of plural extending devices so that the reproduced sounds of all the loudspeakers can arrive at a normal image position at the same time. CONSTITUTION:Based on the coordinates of a point (p) and the coordinate of loudspeakers 108-111 decided in advance, an extending time controller 102 calculates the extending time of extending devices 104-107. Then, the extending time of the extending devices 104-107 is controlled so that the sounds of all the loudspeakers 108-111 can arrive at the point (p) at the same time. Under the control of the extending time controller 102, the reproduced sounds of all the loudspeakers 108-111 arrive at the normal image position (p) at the same time. Then, extremely high sound pressure can be obtained at the point (p) by the in-phase addition of the sounds from all the loudspeakers 108-111. On the other hand, the so much higher sound pressure can not be obtained in a space excepting for the point (p) since the sounds from the respective loudspeakers are added with random phases. Thus, a listener receives an impression just like radiating sounds from the point (p), and the sense of a distance can be controlled as well as the sense of a direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sound image control device that controls a dynamically changing sound image.

BACKGROUND OF THE INVENTION In recent years, in the audio/vinual field, technological trends have been changing from conventional stereo playback to systems that dynamically control sound images in accordance with images.

As a conventional technology, US Patent No. 3,746,792
．． There is a Dolby Surround Active Matrix type sound image control device shown in Nos. 3,632,886 and 3,959,590.

A conventional sound image control device will be described below with reference to the drawings.

This section explains how to encode Dolby Surround.

FIG. 3 is a block diagram showing the configuration of a Dolby Surround encoder. In Figure 3, 301 is the L (left channel) signal input terminal, and 302 is the R (right channel) signal input terminal.
A signal input terminal, 303 is a C (center channel signal) input terminal, 304 is an S (surround channel) signal input terminal, 305 is an attenuator that attenuates the C signal by 3 [dB],
306 is an adder that adds the output of the attenuator 305 to the L signal;
307 is an adder that adds the output of the attenuator 305 to the R signal;
308 is an attenuator that attenuates the S signal by 3 [dB], 309
is the output of the attenuator 308 from 100 [Hz to 7 [kHz]
310 is a modified B-type noise reduction enhancer that encodes the output of the band-pass filter 309, and 311 is a modified B-type noise reduction enhancer that encodes the output of the band-pass filter 309.
+90 [deg1
A phase shifter that creates a signal with a phase difference, 312 is a phase shifter 31
An adder 313 adds -90[deg] output of phase shifter 311 to the output of adder 306;
An adder that adds its output to the output of the adder 307, 314 an Lt signal output terminal that outputs the output of the adder 312 as an Lt (encoder left channel) signal, and 315 an adder 3
This is an R°C signal output terminal that outputs the output of No. 13 as an Rt (encoder right channel) signal.

The operation of the Dolby Surround encoder configured as above will be explained.

The L (left channel) signal input to the Dolby Surround encoder is sent to the speaker placed in front of the left of the listening position in the listening room, the R (right channel) signal is sent to the speaker placed in front of the right, and the C (center channel) signal is sent to the speaker placed in front of the right. ) signal is a signal that has been mixed on the assumption that it will be reproduced by a speaker placed in the front, and the surround channel signal S will be reproduced by two speakers placed at the left and right in the rear. C
The signal is attenuated by 3 [dB] by an attenuator 305 and added to an L signal by an adder 306 and an R signal by an adder 307, respectively. The S signal is attenuated by 3 [dB] by an attenuator 308, and further attenuated by 100 [Hz] by a bandpass filter 309.
The band is limited to 7 [kHz]. band pass filter 30
The output of 9 is a modified B-type noise reduction encoder 31.
Enfooded with 0. This encoding will be discussed later. Modified type B noise reduction tangent encoder 310
The output of is phase-shifted by +90 [d e g] by the phase shifter 311 and added to the output of the adder 306 by the adder 312. The output of the adder 312 becomes the Dolby surround encoder output Lt. Similarly, the output of the modified B-type noise reduction encoder 310 is -90[degl] by the phase shifter 311.
The signal is phase-shifted and added to the output of the adder 307 by an adder 313 to become the Dolby surround encoder output Rt. The above processing can be summarized as equations (1) and (2).

Lt=t, +o, 7C+0. 7js...(
1) Rt=R+0. 7C-0,7js...
・(2) Here, j represents (-1E'2), indicating that the phase rotation is 90 degrees.

The modified B-type noise reduction encoder 310 has an amplitude frequency characteristic that changes depending on the level of the input signal. By decoding this encoded signal, it is possible to reduce the high frequency components of noise generated in the transmission media. Table 1 shows the amplitude frequency characteristics of the modified B-type noise reduction encoder using the input signal level as a parameter.

Below is the margin.

Table 1 Next, a decoder of a Dolby surround active matrix type sound image control device will be explained.

FIG. 4 is a block diagram showing the configuration of a decoder of a Dolby surround active matrix type sound image control device. In FIG. 4, 401 is an input terminal for the encoder output Lt (left channel) signal, 402 is an input terminal for the encoder output Rt (right channel) signal, and 403 is an input for adjusting the balance of the Lt times signal and the Rt times signal. A balance control device, 404, a level control device that adjusts the absolute level of the balanced signal Lt, Rt, 405, an L (left channel) signal, an R (right channel) signal, from the absolute level adjusted signal Lt, Rt; Adaptive matrix 406 generates C (center channel) signal and S (surround channel) signal, adaptive matrix 405
4o7 is a low-pass filter that passes the signal of 7 [kHz] or less of the delayed S signal, and 408 is a low-pass filter that attenuates the noise of the component of the S signal of 7 [kHz] or less. Modified type B noise reduction decoder, 409 is an adaptive matrix 405
410 is a listening room, 411 is a mask level control device for controlling the levels of the L signal, R signal, and C signal output by the decoder, and the S signal output by the modified B-type noise reduction decoder; R speaker 412 is placed in the front right and plays the R signal output from the mask level control device; 412 is the C speaker placed in front of the listening position in the listening room and plays the C signal output from the mask level control device; 413 is placed in front of the left of the listening position in the listening room, and outputs the mask level control device and reproduces the signal.
Reference numeral 14 denotes an S speaker which is placed at the rear right of the listening position in the listening room and reproduces the S signal outputted by the mask level control device, and numeral 415 is placed at the rear left of the listening position in the listening room, and which reproduces the S signal output by the mask level control device. S to output
This is an S speaker that reproduces signals.

The operation of the Dolby surround active matrix sound image control device decoder configured as described above will be described.

The first signal is input to the Dolby Surround Active Matrix sound image control device decoder.

These are encoder outputs Lt and Rt expressed by equation (2).

The input balance control device 403 receives the input signal Lt.

Adjust the balance of Rt. Level control device 404 adjusts the absolute levels of input signals Lt and Rt.

In the adaptive matrix 405, the input signal Lt.

Four output signals, R, C, and S, are created according to the level difference of Rt. Therefore, the input signals Lt, R
It is necessary to adjust the balance and absolute level of t. The processing of the adaptive matrix 405 will be described in detail later. Delay device 406 is adaptive matrix 405
The surround channel signal S of is delayed by 15 to 30 [ms]. The low-pass filter 407 passes signals of 7 [kHz] or less of the delayed surround channel signal S. The modified B-type noise reduction decoder 408 reduces high frequency noise generated in the transmission media included in the surround channel signal S. Table 2 shows the amplitude frequency characteristics of the modified B-type noise reduction decoder 408 using the level as a parameter. The characteristics of the decoder are opposite to those of the encoder shown in Table 1.

The mask level control device 409 in the table is a left channel signal output by the adaptive matrix 405.

right channel signal R1, center channel signal C1, and
This is a quadruple volume that controls the level of the surround channel signal S output by the modified B-type noise reduction decoder 408. The right channel signal R1, the center channel signal C9, the left channel signal, and the surround channel signal S output by the mask level control device 409 are reproduced by speakers 411 to 415 arranged in the listening room.

Here, the adaptive matrix 405 will be explained.

FIG. 5 is a block diagram showing the configuration of the adaptive matrix 405. In FIG. 5, 501 is an Lt input terminal, 502 is an Rt input terminal, 503 is a band pass filter that limits the signal bands of Lt and Rt, and 504 is L'
(band-limited Lt) and R' (band-limited R
t) to produce a C'-fold signal; 505 is a subtracter that takes the difference between L'' and R' and produces a S'-fold signal; 506-5;
09 is a full-wave rectifier circuit that performs full-wave rectification of each of the L', R', and C'' B + signals, 510 is a logarithmic difference circuit that takes the difference DLR between the logarithm of the R'-fold signal and the L'-fold signal, and 511 is S Logarithmic difference circuit that takes the logarithmic difference Dcs of the signal C'' signal, 51
2 is a threshold switch that determines whether the output of the logarithmic difference circuit 510 or 511 is within a predetermined range; 513 is a threshold switch 512;
Depending on the judgment result, the time constant is 22 [ms] or 448 [ms].
A dual time constant circuit 514 processes the output DLR of the logarithmic difference circuit 510 with a low-pass filter of ms.
bitemporal constant circuit 51 that processes the output Dcs of the logarithmic difference circuit 511 with a low-pass filter of l or 448 [msl];
5 is a polarity dividing circuit for creating EL and ER, which is the output of the bitemporal constant circuit 513 multiplied by a coefficient corresponding to its polarity; 516 is Ec, which is the output of the bitemporal constant circuit 514 multiplied by a coefficient corresponding to its polarity; A polarity division circuit 517 generates the input signal Lt by the outputs EL and ER of the polarity division circuit 515 and the outputs Ec and Es of the polarity division circuit 516.
, Rt to control ELLI Et*+ ERLI
ERRI ECLI ECRI EsL+ES
518 is the output of the voltage controlled amplifier 517 E LLI E LRI E IIL
I E RRIECLI ECRI ESLI
This is a coupling network that multiplies the ESR and input signals Lt and Rt by a predetermined constant and adds them, and outputs LIR, C, and S signals.

The operation of the adaptive matrix configured as described above will be described below.

The adaptive matrix 405 calculates the difference in logarithms of signal levels for the LR axis or the O8 axis, and detects from which direction the signal is dominant based on this difference. and,
By outputting signals in the dominant direction as they are and attenuating signals in other directions, the sense of direction of the reproduced sound is emphasized.

The bandpass filter 503 converts the input signals Lt and Rt to 100
Bandwidth is limited to [Hzl~7[kHz].

The outputs L' and R' of the bandpass filter 503 are (1)th,
As shown in equation (2), the main components are the encoder input signal and the R signal, respectively. Additionally, an adder 504,
The output of the subtracter 505 is the (3rd) output.

It is expressed by equation (4).

C' = C + 0.7 (LIR)...
(3) S' =-j S+0.7 (LR)
(4) From equations (3) and (4), it can be seen that c' and s'' each have the C1S signal as their main component.

Each signal of L'R'C' and S' is sent to the full wave rectifier circuit 5.
06 to 509 are full wave rectified. After the aftermath is rectified,
The pairs of L', R' and c', s' are processed by logarithmic difference circuits 510 and 511, respectively, and an output DLRI Dcs is obtained. The processing of the logarithmic difference circuits 510 and 511 is expressed by equations (5) and (6), respectively.

DLR= l o ga (R'/L'
)...(5) Dcs"lo
g. (S'/C') ・ (6
) The output D LR indicates which of the LR is dominant with respect to the LR axis, and the output Dcs indicates which of the O8 is dominant with respect to the O8 axis.

When the level difference between the L and R1 signals or the C signal and the S signal is large, the Threnjord switch 512 outputs the adaptive matrix 405 and outputs the R and C signals.

In order to quickly change each signal of S, a short time constant of 220 m5 of the bi-time constant circuit is selected, and conversely, when the level difference is small, a long time constant of 484 [ms] is selected.
The R, C, and S signals are changed vividly. If the outputs DLRI Dcs of the logarithmic difference circuits 510 and 511 are both within the threshold level ±Lth, the threshold switch 512 is activated by the bitemporal constant circuits 513 and 514.
A time constant of 484 [ms] is selected, and if either one is outside the range, a time constant of 22 [ms] is selected. The time constant ([
ms]) are shown in Table 3.

Table 3 In order to realize Table 3, the threshold switch 51
2 is the output DLRI D of the logarithmic difference circuits 510 and 511
C8 and threshold level ±Lth,! It consists of four comparators that compare = and an AND circuit that ORs the comparator outputs.

The dual time constant circuit 513 integrates the output DLR of the logarithmic difference circuit 510 with a time constant of 484 or 22 [mS] depending on the determination result of the threshold switch 512. The integration circuit must be an RC integrator or one with transient characteristics equivalent to it. The bitemporal constant circuit 514 and the logarithmic difference circuit 511
The output of Similar processing is performed for S.

The polarity dividing circuit 515 generates control voltages EL and ER for the voltage control amplifier 517 in the subsequent stage according to the polarity of the DLR integrated by the bi-temporal constant circuit 513. Control voltage EL, ER
is expressed by equations (7) and (8).

EL=DLRDLR<0 0 DLR>0...(7)E
R=ODLR<0 -DLRDLR>O (8) Similarly, the control voltages Ec and Es of the voltage control amplifier 518 generated by the polarity dividing circuit 518 are expressed by equations (9) and (10).

Ec"Dcs Dcs<0 ODcs>O...(θ) Es=ODcs<0 -Dcs Des>0 ・"(10
) Voltage control amplifier 517 outputs E from polarity dividing circuit 515.
ELLIELRI by controlling the input signals Lt, Rt by L, Ee and the output Ec+Es of the polarity dividing circuit 516.
ERLI EIIIRI ECLI ECRI
Create and output ESLI ESR. Here, the input signal LY controlled by the output EX of the polarity dividing circuit is
It will be expressed as XV. The relationship between the control voltage and amplification factor of the voltage controlled amplifier 517 is shown in FIG.

Coupling network 518 connects the voltage controlled amplifier output ELL
I ELRI ERLI ERRI ECLI
ECRI ESLIESR and input signals Lt, Rt
and are added in the proportions shown in Table 4, and the L, R, C, and S signals are output.

Below is the margin.

Table (Part 1) Table (Part 2) At the output stage of the adaptive matrix 405, an inter-channel separation of 2 [683 or more] can be ensured.

As described above, the Dolby Surround Active Matrix sound image control device decoder detects from which direction the signal is dominant with respect to the LR axis or the C8 axis. Then, if a dominant direction is detected,
Signals in that direction are output as they are, and signals in other directions are attenuated, thereby emphasizing the sense of direction of the reproduced sound. Therefore, sounds with a clear direction, such as dialogue, provide a clear sense of direction. On the other hand, if no dominant direction is detected, a normal stereo effect is obtained.

Problems to be Solved by the Invention However, the conventional configuration described above has a problem in that it is possible to control the sense of direction of the sound image, but it is not possible to control the sense of distance. The present invention solves the above-mentioned conventional problems, and aims to provide a sound image control device that can control not only the sense of direction but also the sense of distance.

Means for Solving the Problems In order to achieve the above object, the sound image control device of the present invention includes a plurality of delay devices that can change delay times, and a delay time of the plurality of delay devices that can change the delay time according to information representing a sound image localization position. and a plurality of speakers arranged at predetermined positions and reproducing the outputs of the plurality of delay devices, respectively, and the delay time control device is arranged to control the sound image localization position p. The delay times of the plurality of delay devices are controlled so that the reproduced sounds of the speakers arrive at the same time.

Operation According to the present invention, with the above-described configuration, the reproduced sounds from all the speakers arrive at the sound image localization position p at the same time under the control of the delay time control device. At point p, the sounds from all the speakers are added in phase, resulting in a very high sound pressure.

On the other hand, in the space other than point p, the sounds from each speaker are added with random phases, so that a very high sound pressure cannot be obtained. Therefore, the listener receives the impression as if the sound is being radiated from the point p, and can control the sense of direction as well as the sense of distance. Furthermore, by continuously changing the position of point p, the sense of movement of the sound image can also be controlled.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a sound image control device in an embodiment of the present invention. In FIG. 1, 101 is a sound image localization position input means, 102 is a delay time control device that controls the delay time of delay devices 104 to 107 according to information representing the sound image localization position, 103 is a signal input terminal, and 104 to 1
07 is a delay device that delays a signal according to the control of the delay time control device 102, and 108 to 111 are arranged at predetermined positions, and are respectively delay devices 104 to 107.
This is a speaker that reproduces the output signal of.

The operation of the sound image control device of this embodiment configured as described above will be described below.

First, the sound image localization position (
Information representing point p) is input. Here, the coordinates of point p (px) are used as information on the sound image localization position.

py, pz) is input (in this embodiment, the coordinate unit is [m]).

The delay time control device 102 calculates the delay times of the delay devices 104 to 107 based on the coordinates of the point p and the predetermined coordinates of the speakers 108 to 111. speaker 108
~111 coordinates 811 821Sn-1+ Sn:
It is assumed that Si (Xi+yi+Zl).

At this time, the distance between point p and each speaker is 1+[:ml(i
=L2+..., n) is given by equation (11).

1:= ((p, -x+) 2+ (p, -y:) 2
+ (pz −z :) 2) ”2...(
11) The distance 11 between point p and each speaker is the coordinate of the maximum speaker S max+ If the distance is 1°aX, is the sound radiated from another speaker? delay device 1 to reach
What is necessary is to control the delay time of 04 to 107. That is,
The delay time τ1 [S] of each delay device is the speed of sound c [m/
sl is given by equation (12).

τ:= (l□x −1+) / c ”'
(12) Therefore, the delay time control device 102 calculates the delay time τ given by equation (12) for the given coordinate p and outputs it to each delay device. delay device 1
04 to 107 delay the input signal by the delay time τ1 given by equation (12). The input signal has a sampling frequency f
For a digital signal of s[Hzl, the delay device is τ1
・It becomes a shift register with fs stages. The delay time is point p
It is determined by the coordinate range of
[ms] is sufficient.

Speakers 108-111 reproduce the outputs of delay devices 104-107. Since the sounds played from the speakers 108 to 111 each have a delay of τ1[s, the speakers 108 to 111 are equimetrically arranged to
A1. =l mat -1: It is placed at the extended point. In other words, it is equivalent to being placed on the circumference of a circle with a radius of 1 square [m] centered on point p. This isometric speaker arrangement is shown in FIG. 2(a).

FIG. 2(b) is a diagram showing the relationship between the signals of each part of the i-th speaker in FIG. 2(a), its delay device, and the n-th speaker located farthest from point p. In Fig. 2(b), 201 is a signal input terminal, 202 is an i-th
the i-th delay device 203 is the i-th speaker 204
is the nth speaker.

Assume that a signal 5ll(t) given by equation (13) is applied to the signal input terminal 201 in FIG. 2(b).

s+! (t)=exl)(jc+,+t)-(13) where ω is the angular frequency of the signal. The delay time τ1 of the delay device 202 is given by equation (14).

τ:= (laa, -1:) / c=Δl:/c
(14) Therefore, the output signal s+(t) of the delay device 202 is expressed by equation (15).

S+ (t)=eXp (,+ω(−τ,))...
-(15) Equation (15) is emitted from the speaker 203. The signal radiated from the speaker 203 is transmitted at a distance of 1. When reaching a distant point p, if the amplitude becomes al due to distance attenuation, the signal S given by equation (16).

(1) becomes.

Sp: (t)=a1・exp[j(ω(t−τ1)−
1,・ω/c) co (16) On the other hand, since the delay time for the speaker 204 is 0 [s co, the signal 5lI(t) given by equation (13) is directly radiated from the speaker 204. be done.

When reaching point p, which is a distance 1188 away, the amplitude becomes a due to distance attenuation. If so, the signal S given by equation (17). (1) becomes.

Son (j)=an” exp (j (ωj−1
nax”ω/C)) (17) Here, by substituting and rearranging equation (14) into equation (16), equation (18) is obtained.

Sp: (t):a1@eXp [(jω(t-r:
)-11・ω/C)] mat・eXp([j(JJ (t-(1++ax-1
,)/c)-1,・ω/C]) mat"eXI)[(Jωt-(lsax-11+ll
) ω/C) co=a, * e xp ((J ωt IIIX・ω
/C)) ... (18) Equation (17) and (
Comparing with Equation 18), it can be seen that the phases are equal. That is, the sounds emitted from the speakers 203 and 204 are added in phase at point p.

Similarly, the sounds emitted from n speakers are all in phase at point p, and the summed amplitude is Σa1,
Generates high sound pressure. On the other hand, the phase of the sound from each speaker is a function of distance and frequency, and at points other than point p, the phases are added at random, so a very high sound pressure cannot be obtained.

Furthermore, if the information representing the sound image localization position (point p) inputted into the sound image localization position input means 101 is continuously changed,
Sound image localization position where the sounds from each speaker are added in phase (
Point p) also changes continuously.

Therefore, the listener hears as if the sound image is moving.

The above is the operation of the sound image control device of this embodiment.

Although the present embodiment uses independent delay devices 104 to 107, it is actually more efficient to use one tapped delay line and switch the signal extraction taps.

Further, in this embodiment, no restrictions are placed on the sound image localization position (point p) and the speaker coordinates S. Therefore, since the delay time of each delay device is different, the same number of delay devices as speakers are required. However, if the speakers are arranged in a grid on the same plane, the sound image localization position (point p) is
If it is limited to a line segment that passes through and is perpendicular to the plane on which the speakers are arranged, the delay times of the delay devices of the speakers located at symmetrical positions with respect to the speaker Sa will be equal. When the speakers are arranged in a grid, there are four speakers located symmetrically with respect to the speaker S, so the number of delay devices can be reduced to 1/4. In particular, when the delay is realized by digital signal processing, by placing constraints on the sound image localization position point (pl) and the speaker coordinates S in this way, the effect of hardware reduction is significant. That is, the number of digital-to-analog converters, which is currently the most costly, is reduced to 1/4, which is economical.

Effects of the Invention As described above, according to the present invention, the reproduced sounds from all the speakers arrive at the sound image localization position p at the same time under the control of the delay time control device. Then, at point p, the sounds from all the speakers are added in the same phase, resulting in a very high sound pressure. on the other hand,
In the space other than point p, the sounds from each speaker are added with random phases, so a very high sound pressure cannot be obtained. Therefore, the listener receives the impression as if the sound is being radiated from the point p, and can control the sense of direction as well as the sense of distance. Furthermore, by continuously changing the point p, it is possible to control the sense of movement of the sound image.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a sound image control device in an embodiment of the present invention, FIG. 2(a) is a diagram showing an isometric speaker arrangement in an embodiment of the present invention, and FIG. ) is an explanatory diagram showing the relationship between the signals of each part of the i-th speaker and its delay device in Fig. 2(a), and the n-th speaker located farthest from point p. FIG. 4 is a block diagram showing the configuration of a surround encoder. FIG. 4 is a block diagram showing the decoder configuration of a conventional Dolby surround active matrix sound image control device. FIG. 5 is a block diagram showing the configuration of the adaptive matrix in FIG. 4. 6 are characteristic diagrams showing the relationship between the control voltage and the amplification factor of the voltage controlled amplifier. 101...Sound image localization position input means, 102...
Delay time control device, 103... signal input terminal, 1
04-107...delay device, 108-111...
・Speaker. Name of agent Patent attorney Akira Okaji and 2 other famous figures 201 --- [No. The father inputs one word and the child's speech ability

Claims (2)

[Claims] (1) A plurality of delay devices that can change the delay time of an input signal, a delay time control device that controls the delay time of the plurality of delay devices according to information representing a sound image localization position, and are arranged at predetermined positions. and a plurality of speakers, each of which reproduces the output of the plurality of delay devices, and the delay time control device controls the plurality of delays so that the sound reproduced by all the speakers reaches the sound image localization position at the same time. A sound image control device that controls the delay time of the device. (2) The sound image control device according to claim 1, wherein the sound image localization position is continuously changed.