JPS59138200A - Reproducing system of car-mounted audio equipment - Google Patents

Abstract

PURPOSE:To attain reproduction with spread effectively by using a 2-channel stereo signal and making speakers arranged in four positions of a car reproduce a signal suitable for the respective arrangement so as to form a wide sound field space in terms of listening. CONSTITUTION:As to high sound frequency components LH, RH of two-channel stereo signals L, R, the LH is reproduced by a left front speaker, the FR is reproduced by a right front speaker FR, (LH-RH)/2 is reproduced by a left rear speaker BL and (RH-LH)/2 is reproduced by a right rear speaker BR respectively. Thus, an ideal form is attained at high frequencies where the effect of separation, direction and position or the like is large. Further, sufficient reproduction is attained even by small sized left and right front speakers FL, FR because of high frequencies. On the other hand, as to low sound frequency components LL, RL, (LL-RL)/2 is reproduced by the left front speaker FL, (RL-LL)/2 is reproduced by the right front speaker FR, the LL is reproduced by the left rear speaker BL and the RL is reproduced by the right rear speaker BR respectively.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides stereo playback signals of two left and right channels of an in-vehicle audio device such as a so-called car stereo. The present invention relates to a reproduction method for reproduction by the speakers arranged at the four locations on the right, and particularly relates to the distribution of reproduction signals to each speaker that can increase the stereo effect and sense of presence.

[Technical background of the invention]

Originally, the left and right two-channel stereo is the left channel.

Playing through the two right speakers should be sufficient. However, in the case of playback from an in-vehicle audio device such as a car stereo, there is no space in the front of the car to place a large speaker, and therefore only poor sound with insufficient bass can be reproduced. On the other hand, there is much more space in the front area at the rear of the car, which allows you to install large speakers, and there is also a partition plate between the trunk room and the inside of the car.
It is also possible to perform reproduction using a large baffle using a rear tray (such as a rear tray) as a speaker baffle. but,
In this case, the reproduced sound that should originally be heard from the front will come from the rear, so there is a problem that a sufficient atmosphere cannot be created, and the human hearing has a reduced ability to separate left and right when it comes to sounds from the rear. There is a problem in that the left and right channel separation sounds as if it has been degraded.

For these playback methods, the front left and front right inside the car.

Speakers are placed at four locations on the rear left and rear right, and the front and rear speakers on the left reproduce the same left channel signal (hereinafter, the left channel signal is referred to as "L signal"), and the front and rear speakers on the right reproduce the same left channel signal (hereinafter, the left channel signal is referred to as "L signal"). There is also a method of reproducing the same right channel signal (hereinafter, the right channel signal is referred to as "R signal") using a speaker.

However, with this method, the listener is forced to listen to the same reproduced sound in front and behind him, which creates a sense of pressure and gives the listener an unnatural feeling of being in a small car.

For these reasons, recently, speakers have been placed in four locations: front pressure, front right, rear left, and rear right, similar to the case described above, and bass sounds are played by the rear speaker and high sounds are played by the front speaker. 0Humans have a low ability to detect directionality when it comes to low frequencies, so even if bass sounds are being played back from the rear speakers, they don't really feel that there are speakers behind them. For this reason, it feels like both high and low frequencies are being output from the front.

However, in this method, although speakers are arranged at four locations, only a normal stereo effect is obtained, which is almost the same as when reproduction is performed using two speakers. In other words, the front speakers are of no use in the low range, and the operating efficiency and effectiveness of the speakers is about half. Despite the fact that In some cases, a sense of expansion of the sound field can be obtained by using this method, but with the above-mentioned method, it becomes difficult to produce such an effect.).

[Purpose of the invention]

The purpose of the present invention is to use a two-channel stereo signal obtained from an in-vehicle audio device to suit each location of speakers placed in four locations: front pressure, front right, rear left, and rear right. To provide a reproduction system for an in-vehicle audio device capable of performing effective reproduction to create a perceptually wide sound field space like a four-channel stereo and giving a sense of spaciousness even in a narrow car interior.

[Summary of the invention]

In the present invention, a difference signal (
L-R or R-L), and at the same time the rear left and right speakers play the low frequency components of the R signal and Ls n, l.
It is characterized in that it reproduces a difference signal (LR or RL) of high-frequency components of burrs. Here, the treble and bass components of the L and R signals basically refer to each band component when the R signal is divided into two bands, treble and bass.゛□ may wrap, and in short, it refers to a component mainly in the high range and a component mainly in the low range.

[Embodiments of the invention]

First, the principle of the present invention will be explained in detail.

To obtain an effect similar to 4-channel stereo while playing a regular (2-channel) stereo record, place it on the front left of the listening position.

There is a method that reproduces the left and right difference signals such as L-R (or R-L) from the rear speakers while reproducing the R signal from the right speaker, and this method is conventionally known. .

There are many reasons why a 4-channel stereo effect can be obtained by outputting the left and right difference signals from the rear, but here we will show some of the typical reasons.

(b) When making records, recording engineers generally record sound effects, such as the reverberation of a concert hall or the applause of the audience, in reverse phase to R. That is, if these sound effects were
If you record in phase with H, the sound image will be localized between the left and right speakers during stereo playback, so the reverberation sound, such as 2 claps, will be heard at a specific point near the center of the front (by changing the L and H levels). (The specific location simply moves between the left and right speakers.), resulting in extremely unnatural playback. On the other hand, if the above-mentioned reverberant two-clap sound is recorded with an opposite phase to H, the sound image will not be localized and will be heard from everywhere. Therefore, most records are recorded in this way.

(b) Two microphones for stereo recording (left).

When the two microphones placed on the right pick up each R signal, the sound generated in the middle (or in the middle direction), or the sound generated near both microphones is 2.
Sound is often picked up by two microphones with the same phase or a close phase relationship. On the other hand, reverberant sound such as two claps generated outside the two microphones or at a relatively distant side has almost opposite phases in both channels at frequencies higher than the frequency corresponding to the wavelength twice the distance between the two microphones. The components tend to be dominant.

Therefore, in terms of sound image localization, the present invention makes it possible to substantially hear the left and right difference signals from the rear speakers in the car, and at the same time, reproduces the above-mentioned bass range signal using the rear speakers. In order to enable reproduction that enhances the feeling that the component is being heard from the front, the front left and right speakers play the R signal, and the rear speaker plays the R signal for the high frequency component. In addition to reproducing the difference signal, the low frequency component is reproduced on the rear left.

The right speaker reproduces the R signal, and the front speaker reproduces the R difference signal.

An embodiment of the present invention based on such a principle will be described in detail.

FIGS. 1(a) and 1(b) respectively show the relationship between the reproduced signal components in the high frequency range and their reproduction positions, and the relationship between the reproduced signal components in the low frequency range and their reproduction positions in this embodiment.

As shown in FIG. 1(a), the high frequency components LH and Rn of the 2-channel stereo signal and R signal are output from the front left speaker FL'? l'L)I, front right speaker F
RH on R, rear left speaker BL (LH-RI+
)/2, and (R,H
-Lll ) /2 respectively.

Therefore, it is an ideal shape for high frequency ranges where the detection ability for separation, direction 1 position, etc. is high, that is, it has a large influence on sound image localization, etc. Furthermore, since the sound is in a high frequency range, the front left and right speakers FL and FR can provide sufficient reproduction even if they are small, which is rather convenient. (Small speakers usually provide better characteristics for high-frequency reproduction.) Also, as shown in Figure 1(b), for the low-frequency components LL and RL of the L and R signals, , front left speaker p't
(LL -Rf-)/2, front right speaker FR
(RL -LL) 7'2, rear left speaker B1
．． to LL, and rear right speaker BR to RL.
Play each.

! Here, the first thing you need to do is to use stereo records, tapes, etc.
In a channel stereo signal, the bass components, that is, the low frequency components, are approximately equal in the left and right channels;
In other words, it is recorded as approximately LL=RL. The reason for recording in this way is, for example, as follows.

(a) When reproducing low frequency sounds, the larger the area of the reproducing vibration system, the higher the radiation efficiency and the better the reproduction.

Therefore, on the recording side, in most records, the left and right bass signals have the same phase and amplitude (LL = R1,)
In other words, it is recorded as a signal that localizes the sound image in the center (in reality, the low frequency range is not localized very clearly), so that the left and right speakers vibrate in the same way.

(b) A record can record large amplitudes, that is, a wide dynamic range, in the horizontal direction of the needle, that is, in the radial direction of the disc, but cannot record large amplitudes in the vertical direction, that is, in the direction perpendicular to the disc surface.

This is because when cutting a record, if the cutter needle goes up too high in the vertical direction, the sound groove will disappear, and if it goes down too much, the sound groove becomes deep, making it easier to apply undue force. Since the amplitude of the signal to be recorded becomes large for the low frequency range signal, the low frequency range signal can only be recorded in the left and right direction. Therefore, for the low frequency range, a signal that cuts left and right, that is, LL, is usually used.
= RL.

This is a tendency for analog records, but the same tendency exists for other media, such as magnetic tapes, because common signals are often used.

In this way, in the bass range, LL and RL are used in most cases, so if the front speakers FL and FR are used to reproduce the left and right difference signals (LT, -fis, components), the front speakers The proportion of low frequency components given to FL and FR becomes extremely small, and
There is no problem even if a small speaker is used as tF'11. The rear speakers BL' and BR have LL, respectively.
RL is given, and the bass frequency components are mainly reproduced from behind the listening position. However, since the overtone components of the bass instrument are reproduced from the front, the bass instrument also sounds as if it is in the front.

In this way, even if the inside of the car is narrow and the front speakers are under poor conditions, such as insufficient reproduction of bass frequencies, an audibly spacious reproduction sound field including reverberation etc. can be created. The sound in front of the upper listener can be heard as if correct stereo reproduction is being performed from bass to treble.

Next, a specific example of a configuration for obtaining signals to be given to each of the speakers FL, FR, 'BL, and BR placed on the front, rear, left, and right sides of the car from a 2-channel stereo signal (L, R signal) using this simple embodiment will be described. show.

In FIG. 2, 1 and 2 are input terminals to which L and R signals, respectively, which are stereo reproduction signals obtained from the main body of the in-vehicle audio device are given; 2, 3.4
and 5 are output terminals that output signals to the speakers placed on the front left, front right, rear left, and rear right, respectively; 7.8 is a polarity inverter that inverts the polarity of the signal; 9 to 12 are capacitors C. The capacitors 13 to 20 are resistors having a resistance value r, and are connected as shown in the figure.

In other words, for the front left speaker FL, the impedance of the capacitor 9 is low in the high frequency range, so the high frequency component LH of the signal is input to the input terminal 1 through the capacitor 9, and is directly output to the output terminal 3, and the high frequency component LH of the signal is output as is to the output terminal 3, and the high frequency component LH of the signal is input to the input terminal 1 through the capacitor 9. In the sound range (because the impedance of capacitors 9 and 10 becomes high), the L signal input to input terminal 1 and the R signal input to input terminal 2 are inverted by polarity inverter 8, resulting in a -R signal.
are coupled via resistors 13 and 14, respectively, and a synthesized signal (LL -RL
)/2 is derived to output terminal 3, and both of these, that is, L)
I and (LL-RL)/2 are simultaneously supplied from the output terminal 3. Similarly, for the front right speaker FR,
In the high frequency range, the high frequency component R)l of the R signal is led out to the output terminal 4 via the capacitor 10, and in the low frequency range, the high frequency component R)l of the R signal is output to the output terminal 4.
The signal and the signal obtained by inverting the above signal by the polarity inverter 7 are coupled via resistors 16 and 15, respectively, and a synthesized signal (RL-LL)/2 of the low frequency component is derived to the output terminal 4. and both of these, RH and (Rr, −L
L)/2 is simultaneously supplied from output terminal 4. Also,
Regarding the rear left speaker BL, the impedance of the capacitor 11 becomes low in the high frequency range, and the signal and the output -R of the polarity inverter 8 are connected to the resistors 17 and 18, respectively.
- A synthesized signal (LH-RH)/2 of high frequency components obtained at this connection point is outputted to the output terminal 5, and the impedance of capacitor 1 is high in the low frequency range. Therefore, the low frequency component LL of the L signal is directly outputted to the output terminal 5 via the resistor 17, and both of them, that is, (LM - R)
I)/2 and LL are simultaneously supplied from output terminal 5. Similarly, for the rear right speaker BR, since the impedance of the capacitor 12 is low in the high frequency range, the R signal and the output -L of the polarity inverter 7 are connected through the resistor 20 and the series circuit of resistor 19 and capacitor 12, respectively. and the synthesized signal (R) of the high frequency components obtained at this connection point.
-L+()/2 is derived to the output terminal 6, and since the impedance of the capacitor 12 becomes high in the low frequency range, the low frequency component RL of the R signal is directly derived to the output terminal 5 via the resistor 20, and both of them, that is, ( RH-LH)
/2 and RL are simultaneously supplied from output terminal 6.

In this way, each of the front pressure, front right, rear left, and rear right speakers FL, FR, BL, and BR has an L
)I+((LL-Rh)/2), .

Rn+((RL-LL)/2), ((LH-R)l
)/2)-+LL and ((R11-LH)/2)+
Signals RL are applied from output terminals 3, 4, 5, and 6 via amplifiers, etc., and are reproduced.

Note that in the present invention, the L-R and R-I components may be used as the difference signal as in the above-mentioned embodiment, but there is an unnaturalness in hearing due to the fact that these components are in an antiphase relationship with each other. In order to soften the sound and make it easier to hear, for example, in Figure 3 (a)
, a transistor Tr, a resistor r, as shown in (b),
Phase shifters 21 and 22 composed of capacitors C or the like may be inserted before the output terminals 4 and 6, respectively, or the left and right difference signals may be shifted by +90°, respectively.

It is also possible to shift the phase by −90° to make the difference signal components in phase.

Also, by using a difference signal component with a different ratio of H, such as using L-0, 7R (or R-Q, 7L) instead of L-R (or R-L) as the difference signal component, Good too,
This ratio may be switched between left and right.

Furthermore, the capacitor 9 to 12° resistor 13 in FIG.
Of course, the values of ~20 may be varied individually, or coils may be used, or an amplifier and an impedance element may be combined like an active filter, and the circuits shown in FIGS. 2 and 3 However, it does not matter what kind of circuit is used to realize a substantially similar method.

It goes without saying that the present invention can be implemented with various modifications without departing from the gist thereof.

〔Effect of the invention〕

According to the present invention, using a two-channel stereo signal,
Speakers placed in four locations inside the car - front left, front right, rear left, and rear right - reproduce signals suitable for each location, creating a wide sound field space that is audibly wide, unlike a 4-channel stereo. It is possible to provide a reproduction method for an in-vehicle audio device that can perform certain effective reproduction.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the principle of an embodiment of the method of the present invention, and FIG. 2 is a circuit configuration diagram showing the configuration of a specific example of a device for signal distribution to which the embodiment is applied. FIG. 3 is a circuit diagram showing the main part configuration of a concrete example according to another embodiment of the present invention. 1.2...Input terminal, 3-6...Output terminal, 7゜8
...Polarity inverter, 9-12...Capacitor, 13-
20...Resistor, 21, 22...Phase shifter. Applicant's agent Patent attorney Takeshi Suzue Hikoga 1 (a) (b) 2 Figure 1]

Claims (1)

[Claims] When reproducing the stereo playback signals of the two left and right channels of the in-vehicle audio system using the speakers placed in the front side, right, and rear left and right in the car, the above-mentioned front pressure and right speaker The high frequency components of the left and right channel signals of the stereo playback signal are respectively reproduced, and the difference signal between the low frequency components of the left and right channel signals is reproduced. A reproduction method for an in-vehicle audio device, characterized in that a low frequency component of a channel signal is reproduced, and a difference signal between high frequency components of the left and right channel signals is reproduced.