JPH1188999A - Acoustic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a speaker system not employing a woofer to use a sound signal for a woofer corresponding to a specified channel in the 5.1 channel system of the Dolby digital (AC-3) system (trade name) for a digital video disk DVD. SOLUTION: In the case of adding a sound signal 21 for a woofer to front left, front right, rear left and rear right speakers S1-S4, high pass filters F1-F4 interrupt a low frequency component that is almost the same as a high frequency of a frequency band 24 of the sound signal 21 for the woofer in the sound signal for the speakers S1-S4 so as to avoid a heavy sense by the low sound frequency band while relieving the load of the speakers S1-S4 and amplifier circuits A1-A4 driving the speakers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an acoustic device,
For more details, for example, DVD (Digital VideoDisk)
Dolby Digital (AC-3) (US Dolby Labora
tories, Inc. The present invention relates to an audio device that reproduces sound using the standardized configuration of the 5.1 channel system of the company name as it is.

[0002]

2. Description of the Related Art In recent years, technological innovation of audio and visual has progressed, and the size of software, that is, a recording medium as a medium has been further reduced in size, and performance has been greatly improved as compared with conventional products. As for the size of the medium, the outer diameter of a compact disk (CD) is φ12 cm, the outer diameter of a mini disk (MD) is φ8 cm, and the magnetic tape of a digital audio tape (DAT) is also small. In addition, DVDs have high-quality video and high-quality sound recorded reproducibly in media of the same size as conventional CDs, and will grow and become the pillars of audio and visual software in the future. Have been.

FIG. 17 shows a Dolby Digital (A) DVD.
It is a block diagram which shows the whole 5.1 channel system of C-3) in a simplified form. The contents of a recording medium of the same size as a CD are read and reproduced by a DVD player 1 and are transmitted via a coaxial cable 2 to a Dolby Digital (AC-
The output signal of 3) is input to the (AC-3) converter 3. The front left speaker S1, the front right speaker S2, the rear left speaker S3, the rear right speaker S4, the woofer S5, and the center speaker S6 arranged at the front center of the listening position face, for example, a listening position in a room used as a home theater or the like. Is provided. The converter 3 outputs sound signals for these speakers S1 to S6 and supplies the sound signals to the control circuit 4. In the control circuit 4, arithmetic processing for improving the sound effect is performed, and the speakers S1 to S6
The audio signals are output to the amplifiers A1 to A6, and the speakers S1 to S6 are driven.

[0004] A standard-grade on-vehicle acoustic device mounted on an automobile is provided with a total of four speakers S1 to S4 of front left, front right, rear left and rear right. Therefore D
To implement the above-described system of VD in connection with such a standard grade car audio system, the system cannot be easily introduced, especially since the woofer S5 is not mounted on the car.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide front left, front right, rear left and rear right speakers, such as a 5.1 channel system of Dolby Digital (AC-3) for DVD. Device that derives an audio signal for a woofer and derives an audio signal having a frequency band for a woofer, and that can perform high-quality sound reproduction without using a woofer It is to provide.

[0006]

SUMMARY OF THE INVENTION The present invention provides a front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, and a rear left speaker provided at the rear left of the listening position. And a rear right speaker provided to the rear right of the listening position, and a sound signal for each of the front left, front right, rear left and rear right speakers, and a woofer provided facing the listening position. A sound source that derives an acoustic signal having a frequency band of: front left, front right, rear left and rear right of the reproducible frequency band of each speaker,
It has the ability to reproduce a part of the frequency band of the audio signal for the woofer, filters the audio signals from the audio source for the front left, front right, rear left and rear right speakers, respectively, and cuts off the cutoff frequency Is the lower frequency band that can be reproduced by the front left, front right, rear left and rear right speakers,
In addition, the high-pass filter selected in the high frequency side of the frequency band of the sound signal for the woofer, and the sound signal for the woofer from the sound source are added to the output of each high-pass filter, and the added output is the front left. , An adder circuit for each of the front right, rear left and rear right speakers.

According to the present invention, as shown in FIGS. 1 to 4 described later, by using a high-pass filter,
The burden on the front left, front right, rear left, and rear right speakers and the amplifier circuit that drives those speakers can be reduced, clipping due to large amplitude can be prevented, and distortion can be reduced.

Further, according to the present invention, the acoustic signal for the woofer is added to the output of each high-pass filter and given to each speaker, so that the acoustic signal for the woofer is divided into the front left, front right, It does not interfere with the low frequencies of the rear left and rear right acoustic signals, and thus can prevent adverse effects such as muffled sound.

The present invention also provides a front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, A rear right speaker provided on the rear right, and a sound signal for each of the front left, front right, rear left and rear right speakers is derived, and has a frequency band for a woofer provided facing the listening position. And a sound source that derives an acoustic signal, wherein the reproducible frequency bands of the front left, front right, rear left, and rear right speakers are equivalent to the frequency band of the acoustic signal for the woofer, and Amplify the acoustic signal for the woofer with a gain of more than one, front left, front right,
An acoustic circuit for adding an acoustic signal for each of the rear left and rear right speakers and providing the added output to the front left, front right, rear left and rear right speakers, respectively. Device.

According to the present invention, as shown in FIGS. 5 to 7 described later, the diameters of the front left, front right, rear left and rear right speakers are relatively large, so that the speakers can be reproduced. The frequency band is the same as the frequency band of the sound signal for the woofer. In such a configuration, the above-described high-pass filter is omitted, and the sound signal for the woofer is amplified and added to each speaker. give. Therefore, these speakers can enhance the low frequency range and increase the power of bass sound.

The present invention also provides a front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, A rear right speaker provided on the rear right, and a sound signal for each of the front left, front right, rear left and rear right speakers is derived, and has a frequency band for a woofer provided facing the listening position. A sound source that derives an acoustic signal, and a frequency band that can be reproduced by any one of the front left and front right or the rear left and rear right speakers,
The frequency band of the audio signal for the woofer is the same as the frequency band of the audio signal for the woofer, and the lower frequency band of the reproducible frequency band of either the front left and front right or the rear left and rear right speakers is It has the ability to reproduce a part of the band, amplifies the audio signal for the woofer from the audio source with a gain of more than 1, and outputs either the front left and front right or the rear left and rear right from the audio source. A first adding circuit that adds the sound signal to one of the speakers and amplifies the added output with a gain exceeding 1, and supplies the amplified signal to each of the one of the speakers; And an acoustic signal for each of the front right or rear left and rear right speakers, respectively, and the cutoff frequency is
A low-pass filter selected from the frequency band reproducible by the other speaker and a high-pass filter selected to a high-frequency side of a frequency band of an audio signal for a woofer, and a woofer from an audio source. A sound apparatus comprising: a second addition circuit that adds an audio signal to an output of each high-pass filter and provides the added output to each of the other speakers.

According to the present invention, as shown in FIGS. 8 and 9 to be described later, for example, the diameter of each speaker of the combination of the front left and the front right is small, while The aperture is large, so the frequency band reproducible by the front left and front right speakers has the ability to reproduce part of the frequency band of the audio signal for the woofer, and each of the rear left and rear right combinations The low band of the frequency band that can be reproduced by the speaker is equivalent to the frequency band of the acoustic signal for the woofer. Therefore, for each of the small-diameter front left and front right speakers, a high-pass filter can be used to reduce the burden on the speakers and the amplifier circuit, prevent clipping due to large amplitude, and reduce distortion.

The large-diameter rear left and rear right speakers are provided without passing through the above-described high-pass filter, and are provided with an enhanced acoustic signal for the woofer.
As a result, it is possible to enhance the low frequency range of each speaker to emphasize the powerful feeling of the bass.

In another embodiment of the present invention, each aperture of the combination of the rear left and rear right speakers is made smaller than the aperture of the combination of the front left and front right speakers, and the rear left and rear rear apertures of the small aperture are combined. An audio signal may be applied to each of the right speakers via a high-pass filter, and the gain of the audio signal for the woofer may be set to 1 or less than 1. In addition, a large-diameter front left and front right speaker is provided with an acoustic signal without passing through a high-pass filter, and an amplified acoustic signal for a woofer with a gain greater than one.

The present invention also provides a front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, A rear right speaker provided on the rear right, and a sound signal for each of the front left, front right, rear left and rear right speakers is derived, and has a frequency band for a woofer provided facing the listening position. An acoustic source for deriving an acoustic signal, wherein the acoustic signal for each of the front left, front right, rear left and rear right speakers from the acoustic source is filtered,
The cutoff frequency is selected as a low band in a frequency band reproducible by each of the front left, front right, rear left and rear right speakers, and a high band in a frequency band of an acoustic signal for the woofer. A high-pass filter, an addition circuit that adds an audio signal for the woofer from the audio source to the output of each high-pass filter, and provides the added output to each of the front left, front right, rear left, and rear right speakers; and A changeover switch for selectively supplying an acoustic signal for a woofer from an acoustic source to an adder circuit corresponding to the front left and front right or the rear left and rear right.

According to the present invention, FIG. 10 and FIG.
As shown in FIG. 1, the sound signal for the woofer is provided to the front left and front right speakers via one switch, or to the rear left and rear right speakers via the other switch. By turning on only one of the changeover switches and turning off the other of the changeover switches in this manner, the low-range sound signal for the woofer is not input to the small-diameter speaker having a low bass reproduction limit, The sound signal for the woofer is added only to the large-diameter speaker. As a result, it is possible to prevent sound cracking from occurring in a small-diameter speaker having a low bass reproduction limit and to reduce distortion. The diameter of each of the front left and front right speakers may be reduced, and the diameter of each of the rear left and rear right speakers may be increased, or vice versa.

The present invention also provides a front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, A rear right speaker provided on the rear right, and a sound signal for each of the front left, front right, rear left and rear right speakers is derived, and has a frequency band for a woofer provided facing the listening position. A sound source that derives an audio signal, the front left, front right, rear left and rear right of the reproducible frequency band of each speaker, the low band is the high band of the frequency band of the sound signal for the woofer. The sound signals for the front left, front right, rear left and rear right speakers from the sound source are substantially identical, and the cutoff frequency is
A high-pass filter selected as a low band in a frequency band reproducible by each of the front left, front right, rear left and rear right speakers and a high band in a frequency band of an audio signal for a woofer; The acoustic signal for the woofer from the source,
An adder circuit for adding to the output of each high-pass filter, and amplifying the output of each adder circuit in the reproducible frequency band of the speaker with a gain exceeding 1, to the front left, front right, rear left and And a booster provided to each of the speakers on the rear right.

According to the present invention, FIG.
As shown in FIG. 3, the output from the adder circuit applied to each speaker is boosted in the low frequency range by a booster to adjust the sound quality, thereby making it possible to enhance the bass and improve the sense of power.

The present invention also provides a front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, A rear right speaker provided on the rear right, and a sound signal for each of the front left, front right, rear left and rear right speakers is derived, and has a frequency band for a woofer provided facing the listening position. A sound source that derives an audio signal, the front left, front right, rear left and rear right of the reproducible frequency band of each speaker, the low band is the high band of the frequency band of the sound signal for the woofer. The sound signals for the front left, front right, rear left and rear right speakers from the sound source are substantially identical, and the cutoff frequency is
A first high-pass filter which is selected as a low band in a frequency band reproducible by the front left, front right, rear left and rear right speakers, and a high band in a frequency band of an audio signal for a woofer; A second high-pass filter for blocking an acoustic signal for the woofer from the acoustic source from a low band lower than a high band of a frequency band of the acoustic signal for the woofer; an output of each first high-pass filter; 2 The output of the high-pass filter is added and the added output is
And an adder circuit for each of the rear left and rear right speakers.

According to the present invention, FIG. 14 and FIG.
As shown in FIG. 5, the acoustic signal for the woofer is
Due to the high-pass filter, the lower frequency band of the reproducible frequency band of the front left, front right, rear left and rear right speakers, which is almost the same, is lower than the high frequency band of the audio signal for the woofer. Since the low frequencies are cut off, the loudspeaker below the reproduction limit, which is not capable of sufficient reproduction with such speakers, cuts off the lowest frequency of the sound signal, and derives the signals of the other bands from the second high-pass filter. And add. As a result, sound breakage of the speaker can be prevented, and reproduction with less distortion can be performed.

The present invention also provides a front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, A rear right speaker provided on the rear right, and a sound signal for each of the front left, front right, rear left and rear right speakers is derived, and has a frequency band for a woofer provided facing the listening position. A sound source that derives an audio signal, the front left, front right, rear left and rear right of the reproducible frequency band of each speaker, the low band is the high band of the frequency band of the sound signal for the woofer. The sound signals for the front left, front right, rear left and rear right speakers from the sound source are substantially identical, and the cutoff frequency is
A high-pass filter selected as a low band in a frequency band reproducible by each of the front left, front right, rear left and rear right speakers and a high band in a frequency band of an audio signal for a woofer; A limiter that limits the amplitude of the acoustic signal for the woofer from the source, the output of each high-pass filter and the output of the limiter are added, and the added output is the front left, front right, rear left, and rear right speakers And an adder circuit for each of the following.

According to the present invention, as shown in FIG. 16 to be described later, the amplitude of the acoustic signal for the woofer is limited by the limiter and then applied to the adder circuit. The performance can be improved within the limit of the reproducible capacity of the speaker while ensuring a sufficient feeling of volume and punch. The limiter also acts as a compressor to suppress the acoustic signal for the woofer.

[0023]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention. In the Dolby Digital (AC-3) 5.1 channel system of DVD,
The video and audio signals are stored in a recording medium of the same size as a compact disc, read and reproduced by the reproducing means 11 as a player, and the (AC-
3) The output signal is supplied to the converter 1 via the coaxial cable 12.
3 given.

The converter 13 derives signals for the front left speaker S1, front right speaker S2, rear left speaker S3 and rear right speaker S4 facing the passenger compartment 16 which is the listening position in the automobile 15 shown in FIG. At the same time, an audio signal for the woofer is derived, and an audio signal for the center speaker S6 disposed at the front center and facing the vehicle interior 16 is derived, and is provided to the control circuit 14. Cabin 16
A driver seat 45 and a passenger seat 46 are provided at the front of the vehicle, and a rear seat 47 is provided at the rear. Control circuit 14
Then, the sound signal is arithmetically processed to derive the sound signals for the front left, front right, rear left and rear right speakers S1 to S4 on lines 17 to 20, respectively, and the sound signal for the woofer on line 21. , And an acoustic signal for the center speaker S6 is derived to a line 22. The acoustic signals on the lines 17 to 20 are high-pass filters F1 to F1.
F4. Each output of the high-pass filters F1 to F4 is provided to one input of each of the adders AD1 to AD4. The other input of the adder circuits AD1 to AD4 is supplied with an acoustic signal for the woofer from the line 21. The outputs of the adders AD1 to AD4 are connected to the amplifier A1.
To A4, whereby the speakers S1 to S4 are respectively driven. Further, the acoustic signal derived from the control circuit 14 to the line 22 is provided to the amplifier circuit A6, which drives the center speaker S6.

FIG. 3 is a diagram showing frequency characteristics in the embodiment of the present invention shown in FIG. Speaker S1
S4 have a relatively large diameter and a frequency characteristic 23. The frequency characteristics 23 of the speakers S1 to S4 have, for example, a frequency range of −3 dB of 50 Hz to 20 kHz, and the slope of attenuation of the frequency characteristics 23 in the low band and the high band is 6 dB / oct. The frequency characteristic 24 of the acoustic signal for the woofer derived from the line 21 is-
The range of 3 dB is 100 Hz or less, and the high frequency slope of the frequency range is 12 dB / oct.

The high-pass filters F1 to F4 have a frequency characteristic 25 shown in FIG. This frequency characteristic 25
Has a cut-off frequency fc in the lower frequency band of the reproducible frequency band having the frequency characteristic 23 of the speakers S1 to S4 and in the higher frequency side of the frequency band of the frequency characteristic 24 of the acoustic signal for the woofer. For example, in this embodiment, fc = 30 Hz is selected, and its slope is 6
dB / oct.

FIG. 4 is an electric circuit diagram showing a specific configuration of the adders AD1 to AD4. These adder circuits AD
1 to AD4 have operational amplifiers 26 to 29, respectively.
The non-inverting input terminal includes resistors R11, R21, R3
1 and R41, the outputs of the high-pass filters F1 and F4 are given, and the resistors R12, R22 and R3
2, an audio signal for the woofer from the line 21 via R42 is given and added. The inverting input terminal is kept at a constant potential, for example, grounded. When the level of each sound signal derived from the control circuit 14 to the lines 17 to 22 is set to the same value to a predetermined gain corresponding to the amplitude thereof, and there is no attenuation of the high-pass filters F1 to F4. , The resistance values are all equal (R11 =
R12 = R21 = R22 = R31 = R32 = R41 = R
42). The resistances R11 to R42 also indicate resistance values. In this way, by the functions of the high-pass filters F1 to F4, the burden on the speakers S1 to S4 and the amplifier circuits A1 to A4 can be reduced, clipping due to large amplitude can be prevented, and distortion can be reduced. This high-pass filter F1
And the sound signal for the woofer is added to the sound signal that has passed through the high-pass filters F1 to F4, so that the low-frequency component of the sound signal from the lines 17 to 20 and the sound signal for the woofer are changed. Without interference,
There will be no muffled sound.

FIG. 5 is a block diagram showing another embodiment of the present invention. This embodiment is similar to the above-described embodiment, and corresponding portions are denoted by the same reference numerals. In this embodiment, the speakers S1 to S4 have a large diameter, and the frequency characteristics thereof are-
The range of 3 dB is 50 Hz to 20 kHz, and the slope of the low band and the high band is 6 dB / oct.

As is apparent from FIG.
The reproducible frequency band indicated by the frequency characteristic 25a in S4 is equivalent to the frequency band of the frequency characteristic 24 of the acoustic signal for the woofer from the line 21.

In the embodiment of the present invention, the above-mentioned high-pass filters F1 to F4 are omitted, and as shown in FIG. So that the ratio of the gain of the acoustic signal of

[0031]

(Equation 1)

Thus, the acoustic signal from line 21 is
It is amplified at a gain greater than 1, for example, gain 2 in this embodiment, and added together with the audio signals from the gain 1 lines 17-20 in adders AD1-AD4, respectively.

FIG. 8 is a diagram showing frequency characteristics of another embodiment of the present invention. This embodiment is based on FIGS.
Similar to the embodiment of FIG. 4, corresponding parts are denoted by the same reference numerals. It should be noted that in this embodiment, the frequency characteristics of the front left and front right speakers S1 and S2 are as shown in FIG.
As indicated by reference numeral 25 in FIG. Each of the rear left and rear right speakers S3 and S4 has the frequency characteristic 23 of FIG. 8 and has a large diameter. The reproducible frequency band of the frequency characteristic 25 of the speakers S1 and S2 is
Higher than the frequency band of the acoustic signal for the woofer having Further, in the low frequency range of the reproducible frequency band having the frequency characteristic 23 of the speakers S3 and S4, a part of the frequency band of the acoustic signal for the woofer having the frequency characteristic 24 can be reproduced.

FIG. 9 is an electric circuit diagram showing a specific configuration of the adders AD1 to AD4 of the embodiment shown in FIG. In the embodiment of FIGS. 8 and 9, lines 19,
In order to amplify the audio signal of unit 20 with a gain of 1 and the audio signal for the woofer from the line 21 with a gain of more than 1, for example, a gain of 2, the adder circuits AD3 and AD4 have resistance values as shown in equation 2. Is determined.

[0035]

(Equation 2)

The high-pass filters F1 and F2 have the same configuration as that of the above-described embodiment, that is, the cut-off frequency is 3
0 Hz and has a slope of 6 dB / oct. Therefore, the acoustic signals from the lines 17 and 18 are
, But these high-pass filters F
By the action of F1 and F2, the low band of the frequency band is cut off as shown in the frequency characteristic 25. The audio signals from the high-pass filters F1 and F2 are added together with the audio signal for the woofer from the line 21 with a gain of 1 and an addition circuit AD.
1 and AD2.

R11 = R12 = R21 = R22 (3) As a result, in the large-diameter speakers S3 and S4, the low frequency range can be enhanced, and in the small-diameter speakers S1 and S2, an extra band can be cut.

FIG. 10 is a block diagram showing still another embodiment of the present invention. This embodiment is based on FIGS.
Similar to the embodiment of FIG. 4, corresponding parts are denoted by the same reference numerals. Note that in this embodiment, the acoustic signal for the woofer from line 21 is the switch 31,
32 via a changeover switch 33 comprising an adder circuit A
D1, AD2; given to AD3, AD4. In this embodiment, for example, the speakers S1 and S2 are small in diameter and have the frequency characteristic 25 of FIG. 8 as described above, whereas the speakers S3 and S4 have the frequency characteristic 23 of FIG. , Large diameter. At this time, the switch 31 is turned off and the switch 32 is turned on. As a result, the small-diameter speakers S1 and S2 having a low bass reproduction limit have low
Does not provide an acoustic signal for a woofer having a bass band. A large-diameter speaker S having a good bass reproduction limit.
A sound signal for a woofer is added to 3, S4. In this way, sound cracking due to input of an acoustic signal for a woofer outside the low-frequency sound reproduction limit to the small-diameter speakers S1 and S2 is prevented, and distortion is prevented from being generated.

In the acoustic device mounted on the automobile 15, the rear left and rear right speakers S3 and S4 have a relatively large diameter, and for example, a trunk room can be used as a baffle room. In FIG.
0 embodiment is implemented. Conversely, in a configuration in which the speakers S1 and S2 are large in diameter and the bass reproduction limit is good, and the speakers S3 and S4 are small in diameter and the bass reproduction limit is low, the switch 31 is turned on. The switch 32 is turned off.

FIG. 11 is an electric circuit diagram showing a specific configuration of the adders AD1 to AD4 in the embodiment shown in FIG. In this embodiment, lines 17-2
The gains of the sound signal provided from 0 through the high-pass filters F1 to F4 and the sound signal for the woofer from the line 21 are made equal and added. Therefore R11 =
R12 = R21 = R22 = R31 = R32 = R41 = R
42.

FIG. 12 is a block diagram showing still another embodiment of the present invention. This embodiment is based on FIGS.
Similar to the embodiment of FIG. 4, corresponding parts are denoted by the same reference numerals. It should be noted that in this embodiment, the outputs of the adders AD1 to AD4 are applied to boosters B1 to B4 to adjust the sound quality, and the outputs of these boosters B1 to B4 are applied to the amplifiers A1 to A4, respectively.

FIG. 13 is a diagram showing frequency characteristics of the embodiment shown in FIG. The frequency characteristics of the acoustic signals from the lines 17 to 20 and the output sound pressures of the speakers S1 to S4 are indicated by reference numeral 23 in FIG. Line 2
The frequency characteristic of the acoustic signal for the woofer from 1 is indicated by reference numeral 24. In the embodiment of the present invention, the booster B
1 to B4 have frequency characteristics 35. The frequency characteristic 35 enhances the amplitude of the signal of about 70 Hz, and the slope of attenuation on both sides thereof is, for example, 12 dB / oct, which is larger than the slope of the frequency characteristic 23. Boosters B1 to B4
About 70 in this frequency characteristic 35
Hz is 16 cmφ for cones as speakers S1 to S4
Is used, its lowest resonance frequency f0
Is about 70 to 80 Hz, in order to match the lowest resonance frequency f0.
It works to block frequency components less than zero. Thus, the speakers S1 to S4 are actuated by the boosters B1 to B4 as indicated by reference numeral 36.
Frequency characteristics prominent near the lowest resonance frequency f0 of 1 to S4 are obtained. In this way, excessive low frequency components included in the audio signal for the woofer are slightly cut off by using the boosters B1 to B4, and a signal including a component in a frequency band that can be reproduced by the speakers S1 to S4 is reproduced. As a result, sound breakage of the speakers S1 to S4 can be prevented, and reproduction with less distortion can be performed.

FIG. 14 is an electric circuit diagram of another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIGS. 1 to 4 described above, and corresponding parts are denoted by the same reference numerals. In this embodiment, the acoustic signal for the woofer from the line 17 is supplied to another high-pass filter F5, and the output of the high-pass filter F5 is supplied via a line 37 to addition circuits AD1 to AD4.

FIG. 15 is a diagram showing frequency characteristics of the embodiment of the present invention shown in FIG. The high-pass filter F5 has a frequency characteristic indicated by reference numeral 38 in FIG. This frequency characteristic 38 converts the audio signal having the frequency characteristic 24 from the line 21 into a high frequency band (for example, less than 70 Hz but lower than a frequency band near 70 Hz) of the audio signal for the woofer. (For example, a frequency band around 10 Hz and less than 10 Hz). In this embodiment, the cut-off frequency fc of the filter F5 is 10 Hz, and its slope is 6 dB / o.
ct, and may be the same as the slope of the frequency characteristic 23 of the speakers S1 to S4. Thus, in the lowest frequency range of the audio signal for the woofer, the speakers S1 to S4 cannot reproduce sufficiently.
The band below the reproduction limit of 1 to S4 is converted to a high-pass filter F.
5, and the sound signal after the interruption is added to an adder A
D1 to AD4 and add. Thus, the speaker S1
S4 can be prevented from cracking and reproduction with less distortion can be performed.

FIG. 16 is an electric circuit diagram showing the entire configuration of another embodiment of the present invention. This embodiment is similar to the embodiment of FIGS. 1 to 4 described above, and corresponding parts are denoted by the same reference numerals. It should be noted that in this embodiment, the acoustic signal for the woofer which is led out on line 21 is provided to a limiter 39 to limit its amplitude.
The output of limiter 39 is applied to adder A via line 40.
D1 to AD4. The limiter 39 also functions as a compressor for suppressing the acoustic signal from the line 21. In this way, the performance can be improved within the capability range of the speakers S1 to S4, while sufficiently securing a feeling of volume such as low volume and a feeling of punch.

The center speaker S6 has a large diameter and has the same frequency characteristics as the frequency characteristics 23 described above.

The present invention can be implemented not only in connection with a vehicle-mounted acoustic device but also in a wide range in relation to other acoustic devices.

[0048]

According to the first aspect of the present invention, for example, D
Utilizes VD's Dolby Digital (AC-3) 5.1 channel system, which derives acoustic signals for the front left, front right, rear left and rear right speakers, and frequency for the woofer. When a sound signal having a band is derived and the sound signal for this woofer is added to the sound signals of the front left, front right, rear left and rear right speakers, a sound signal to be given to those speakers by a high-pass filter , The load on the speaker and the amplifier circuit for the speaker can be reduced, clipping due to large amplitude can be prevented, and distortion can be reduced. In the present invention, by adding a sound signal for the woofer, it is possible to avoid using a high-pass filter to avoid adverse effects such as muffled sound due to interference with the low frequency range of the sound signal for the speaker. In addition, the muffled feeling in the low frequency band can be prevented.

According to the second aspect of the present invention, in a configuration in which the speaker has a large diameter and the reproduction frequency band is equivalent to the frequency band of the acoustic signal for the woofer, the acoustic signal for the woofer is 1 Amplification is performed with a gain exceeding?, And addition is performed, whereby the low frequency band can be enhanced.

According to the third aspect of the present invention, one of the combination of the front left and front right speakers or the combination of the rear left and rear right speakers has a large diameter in a configuration having a small diameter. Acoustic signals are given to speakers of a combination of apertures without providing a high-pass filter,
The sound signal for the woofer is amplified with a gain of more than 1 and given, thereby enabling low-frequency reproduction.
To the small-diameter combination speaker, an acoustic signal is applied through a high-pass filter, and an acoustic signal for the woofer is applied without enhancement. The load on the large-diameter speaker and the amplifier circuit for driving the large-diameter speaker can be reduced to prevent clipping due to large amplitude, to reduce distortion, and to eliminate the feeling of muffled sound in the low frequency band.

According to the fourth aspect of the present invention, the sound signal for the woofer is supplied to the combination of the front left and front right speakers or the rear left and rear right speakers by the changeover switch. No sound signal for the woofer, which is a low-frequency band, is given to the side of the combination of small-diameter speakers having a low bass reproduction limit, and the sound for the woofer is combined with the combination of large-diameter speakers having a good bass reproduction limit. The signals can be added, thereby preventing sound cracking and constructing a system with less distortion.

According to the fifth aspect of the present invention, the sound signals for the woofers are added to the sound signals for the front left, front right, rear left and rear right speakers, and then each of those channels is added. By subjecting the signal to low-frequency boosting by a booster, performing equalizing processing, and performing sound quality adjustment, bass enhancement can be achieved, and a sense of power can be improved.

According to the invention of claim 6, the frequency band of the sound signal for the woofer extends to a lower frequency than the sound signal for the loudspeaker, and therefore the sound signal for such a woofer is reduced. When applied to the speaker as it is, the problem that the load on the speaker and the amplifier circuit becomes excessive is solved.
The low-frequency component in the frequency band of the audio signal for the woofer is given to the high-pass filter and added to the audio signal for the loudspeaker, and thus the excess low-frequency component in the audio signal for the woofer is slightly cut off. A sound signal containing a frequency band component that can be reproduced by the speaker is reproduced. As a result, sound breakage of the speaker can be prevented, and reproduction with less distortion can be performed.

According to the seventh aspect of the present invention, the sound signal for the woofer is subjected to a compressor and a limiter processing to emphasize the low-pitched sound, that is, the low-pitched sound and the punch, and to sufficiently secure the sound. The performance can be improved within the capacity limitation of the above.

[Brief description of the drawings]

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

FIG. 2 is a simplified plan view showing a cabin 16 of an automobile 15;

FIG. 3 is a diagram showing a frequency characteristic in the embodiment of the present invention shown in FIG. 1;

FIG. 4 is an electric circuit diagram showing a specific configuration of addition circuits AD1 to AD4.

FIG. 5 is a block diagram of another embodiment of the present invention.

FIG. 6 is a diagram showing frequency characteristics in the embodiment shown in FIG.

FIG. 7 is an electric circuit diagram showing a specific configuration of adders AD1 to AD4 in the embodiment shown in FIGS. 5 and 6;

FIG. 8 is a diagram illustrating frequency characteristics of another embodiment of the present invention.

9 is a diagram illustrating the addition circuit AD1 of the embodiment shown in FIG.
FIG. 3 is an electric circuit diagram showing a specific configuration of AD4.

FIG. 10 is a block diagram showing the overall configuration of another embodiment of the present invention.

11 is an electric circuit diagram showing a specific configuration of adders AD1 to AD4 in the embodiment shown in FIG.

FIG. 12 is a block diagram of still another embodiment of the present invention.

FIG. 13 is a diagram showing frequency characteristics in the embodiment shown in FIG.

FIG. 14 is an electric circuit diagram of another embodiment of the present invention.

FIG. 15 is a diagram showing frequency characteristics of the embodiment of the present invention shown in FIG.

FIG. 16 is an electric circuit diagram showing the entire configuration of another embodiment of the present invention.

FIG. 17 is a simplified block diagram showing the entire 5.1-channel system of DVD Dolby Digital (AC-3).

[Explanation of symbols]

 Reference Signs List 11 reproducing means 13 converter 14 control circuit 15 automobile 16 cabin 26-29 operational amplifier 31, 32, 33 switch 39 limiter A1-A4 amplifying circuit AD1-AD4 adding circuit B1-B4 booster F1-F5 high-pass filter S1-S4, S6 Speaker

Claims (7)

[Claims] 1. A front left speaker provided at the front left of the listening position; a front right speaker provided at the front right of the listening position; a rear left speaker provided at the rear left of the listening position; A rear right speaker provided, and the front left, front right, rear left and rear right to derive an acoustic signal for each speaker, and a sound signal having a frequency band for a woofer provided facing the listening position. Ability to reproduce a part of the frequency band of the audio signal for the woofer, including the audio source to be derived, and the lower frequency band of the reproducible frequency bands of the front left, front right, rear left, and rear right speakers And filters the acoustic signals from the sound source for the front left, front right, rear left and rear right speakers, respectively, and the cutoff frequencies thereof are the front left, front right, rear left and rear right speakers, respectively. Low reproducible frequency band High-pass filter selected in the high frequency side of the frequency band of the acoustic signal for the woofer, and the acoustic signal for the woofer from the acoustic source are added to the output of each high-pass filter and added. Outputs left, right,
An acoustic circuit, comprising: an adder circuit provided to each of the rear left and rear right speakers. 2. A front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, and a rear right speaker of the listening position. A rear right speaker provided, and the front left, front right, rear left and rear right to derive an acoustic signal for each speaker, and a sound signal having a frequency band for a woofer provided facing the listening position. And the sound source to be derived, the reproducible frequency band of each of the front left, front right, rear left and rear right speakers is equivalent to the frequency band of the sound signal for the woofer, and for the woofer from the sound source. Amplify the audio signal of the above with a gain of more than 1, and add it to the audio signals for the front left, front right, rear left and rear right speakers, and add the added output to the front left,
An acoustic circuit, which includes an adder circuit for each of the front right, rear left, and rear right speakers. 3. A front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, and a rear right speaker of the listening position. A rear right speaker provided, and the front left, front right, rear left and rear right to derive an acoustic signal for each speaker, and a sound signal having a frequency band for a woofer provided facing the listening position. The sound source to derive, and the frequency band that can be reproduced by any one of the front left and front right or rear left and rear right speakers is equivalent to the frequency band of the sound signal for the woofer, and the front left and front The lower part of the reproducible frequency band of either the right or the rear left and the rear right speaker has the ability to reproduce a part of the frequency band of the audio signal for the woofer, and the woofer from the sound source For Amplifying the audio signal with a gain greater than 1 and adding to the audio signal for each of the front left and front right or back left and back right speakers from the sound source, and adding the summed output to A first adder circuit for amplifying with a gain exceeding 1 and applying the amplified signal to each one of the speakers; and a front left and a front right or a rear left and a rear right from the sound source for the other one of the speakers. Each of the acoustic signals of the filter, the cut-off frequency is the lower frequency band that can be reproduced by the other speaker,
And a high-pass filter selected on the high frequency side of the frequency band of the sound signal for the woofer, and the sound signal for the woofer from the sound source is added to the output of each high-pass filter. Or a second adder circuit for each of the other speakers. 4. A front left speaker provided on the front left of the listening position, a front right speaker provided on the front right of the listening position, a rear left speaker provided on the rear left of the listening position, and a rear right speaker of the listening position. A rear right speaker provided, and the front left, front right, rear left and rear right to derive an acoustic signal for each speaker, and a sound signal having a frequency band for a woofer provided facing the listening position. A sound source to be derived, and filters the sound signals from the sound source for the front left, front right, rear left and rear right speakers, respectively, wherein the cutoff frequencies are front left, front right, rear left and A high-pass filter that is selected in the lower frequency band of the frequency band that can be reproduced by each speaker on the rear right and in the higher frequency band of the audio signal for the woofer, and an audio signal for the woofer from the audio source The each high pass Add the output of the filter and add the output to the front left, front right,
An adder circuit for providing each of the rear left and rear right speakers, and a selector switch for selectively providing an audio signal for the woofer from the sound source to the adder circuit corresponding to the front left and front right or the rear left and rear right An acoustic device comprising: 5. A front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, and a rear right speaker of the listening position. A rear right speaker provided, and the front left, front right, rear left and rear right to derive an acoustic signal for each speaker, and a sound signal having a frequency band for a woofer provided facing the listening position. The low frequency range of the reproducible frequency bands of the front left, front right, rear left and rear right speakers is almost the same as the high frequency range of the audio signal frequency band for the woofer. Yes, the acoustic signals for the front left, front right, rear left and rear right speakers from the sound source are respectively filtered, and the cutoff frequency is determined by the front left, front right, rear left and rear right speakers. In the lower frequency range of the reproducible frequency band, A high-pass filter selected as a high frequency band in the frequency band of the audio signal for the woofer, and an addition circuit for adding the audio signal for the woofer from the audio source to the output of each high-pass filter, The output of the adder circuit is amplified in the lower frequency range of the reproducible frequency band of the speaker with a gain exceeding 1, and the front left, front right,
An acoustic device comprising: a booster provided to each of a rear left speaker and a rear right speaker. 6. A front left speaker provided on the front left of the listening position, a front right speaker provided on the front right of the listening position, a rear left speaker provided on the rear left of the listening position, and a rear right speaker of the listening position. A rear right speaker provided, and the front left, front right, rear left and rear right to derive an acoustic signal for each speaker, and a sound signal having a frequency band for a woofer provided facing the listening position. The low frequency range of the reproducible frequency bands of the front left, front right, rear left and rear right speakers is almost the same as the high frequency range of the audio signal frequency band for the woofer. Yes, the acoustic signals for the front left, front right, rear left and rear right speakers from the sound source are respectively filtered, and the cutoff frequency is determined by the front left, front right, rear left and rear right speakers. In the lower frequency range of the reproducible frequency band, And the first selected in the high frequency band of the frequency band of the acoustic signal for the woofer.
A high-pass filter, a second high-pass filter that blocks an audio signal for the woofer from the acoustic source from a low-frequency band lower than a high-frequency band of the audio signal for the woofer, and a first high-pass filter. An acoustic circuit, comprising: an adder for adding an output and an output of the second high-pass filter, and providing the added output to each of the front left, front right, rear left, and rear right speakers. 7. A front left speaker provided at the front left of the listening position, a front right speaker provided at the front right of the listening position, a rear left speaker provided at the rear left of the listening position, and a rear right speaker provided at the listening position. A rear right speaker provided, and the front left, front right, rear left and rear right to derive an acoustic signal for each speaker, and a sound signal having a frequency band for a woofer provided facing the listening position. The low frequency range of the reproducible frequency bands of the front left, front right, rear left and rear right speakers is almost the same as the high frequency range of the audio signal frequency band for the woofer. Yes, the acoustic signals for the front left, front right, rear left and rear right speakers from the sound source are respectively filtered, and the cutoff frequency is determined by the front left, front right, rear left and rear right speakers. In the lower frequency range of the reproducible frequency band, And a high-pass filter selected in the high frequency band of the sound signal for the woofer, a limiter for limiting the amplitude of the sound signal for the woofer from the sound source, and an output and limiter for each high-pass filter And an adding circuit for adding the added output to each of the front left, front right, rear left and rear right speakers.