JPH04158700A - On-vehicle acoustic equipment - Google Patents

Abstract

PURPOSE:To obtain a pleasant sound field by separating a direct sound into three bands, a log sound frequency component, a medium sound frequency component and a high sound frequency component, adjusting the arrival time so that each component reaches simultaneously to both ears of a listener and reflecting the high sound frequency component onto a side glass. CONSTITUTION:The equipment is provided with high sound frequency speaker pair 36, 36' arranged toward a side glass to front left and right of a cabin, medium sound frequency speaker pair 38, 38' arranged respectively to front left right of the cabin, medium sound frequency speaker pair 39, 39' arranged respectively in the vicinity of left and right doors of the cabin, a signal separation means 2 separating the signal from a sound source into a low sound frequency component, a medium sound frequency component and a high sound frequency component, and delay means 19-22 delaying the low sound frequency component, the medium sound frequency component and the high sound frequency component and supplying the result to the speaker pair so as to reach both ears of a listener simultaneously. Thus, optimum sound state is realized in the cabin and a pleasant sound field is offered to the listener.

Description

[Detailed description of the invention] [Industrial application fields] TECHNICAL FIELD The present invention relates to an in-vehicle audio device mounted in a vehicle interior.

[Summary of the Invention] The present invention provides a pair of high-frequency speakers arranged at least on the front left and right sides of a vehicle interior facing the side windows, and a single-chamber ff.
A pair of mid-range speakers arranged on the left and right sides of the J direction, a pair of low-range speakers arranged on the left and right doors of the passenger compartment, and a pair of mid-range speakers arranged near the left and right doors of the passenger compartment, respectively; signal separating means for separating the signal from the sound source into at least a low frequency component signal, a mid frequency component signal and a high frequency component signal; The present invention is equipped with delay means for supplying signals to a pair of speakers for the mid-range range, a pair of mid-range speakers, and a pair of treble-range speakers, thereby realizing an optimal acoustic state in the vehicle interior and providing a comfortable sound field to the listener.

[Conventional technology] Conventional car speaker systems are generally 4-speaker systems, but in recent years, 6-speaker systems have become mainstream, and in the past, full-range speakers have been installed. .

The reason for this is that the space for installing speakers is small in the vehicle interior, and a full-range type is the most effective.

[Problem to be solved by the invention C] However, full-range type emits from low-frequency components to high-frequency components, which places more emphasis on the overall balance, so when focusing on bass and treble, it leaves something to be desired. . Therefore, it has been difficult to achieve powerful bass reproduction, crisp bass, and clear treble inside the vehicle.

From a speaker installation perspective, conventionally speakers are often installed near the foot of the door.

In this case, the sound was blocked by the occupant's feet, etc., and there was an impression that the high frequency range was particularly lacking.

As a result, coloration occurred when people rode on it, making it unavoidable to feel uncomfortable. Also, traditionally.

In order to create a sense of spaciousness, antiphase components were added to the left and right signal outputs, and direct sound and early reflected sound were emitted from the same speaker. However, in both methods, the transmission frequency characteristics change, giving a sense of accomplishment.

Furthermore, reverberation is an important element in achieving a comfortable sound field. Reverberation time is a physical measure that expresses this feeling of reverberation.

Conventionally, it has been difficult to achieve this sense of spaciousness and pleasant reverberation inside a vehicle interior.

SUMMARY OF THE INVENTION An object of the present invention is to provide an in-vehicle audio device that achieves optimal acoustic conditions in a vehicle interior and creates a comfortable sound field for listeners.

[Means for Solving the Problem] In order to achieve the above object, the in-vehicle audio device of the first invention of the present application includes a pair of high-frequency speakers arranged at least in the front left and right sides of the vehicle interior, respectively, facing the side glass. , a pair of mid-range speakers arranged on the left and right sides of the steering force of the vehicle interior, and a pair of low-range speakers respectively arranged on the left and right doors of the vehicle interior, transmitting signals from the sound source to at least a low-frequency component signal, a signal separating means for separating into a sound range component signal and a high range component signal; a first delay means for delaying the low range component signal and supplying the delayed range to the low range speaker pair; and a first delay means for delaying the mid range component signal. The present invention is characterized by comprising a second delay means for supplying the mid-range speaker pair, and a third delay means for delaying the treble-range component signal and supplying the delayed treble-range component signal to the treble-range speaker pair.

Further, a second invention of the present application is the device of the first invention, which further includes a second pair of high-frequency speakers arranged on the upper left and right sides of the vehicle compartment, and a second pair of high-frequency speakers arranged above the left and right doors of the vehicle compartment, respectively. generating an early reflected sound signal from a second sound range speaker pair, a center speaker disposed in the front center of the vehicle interior facing the windshield, and the high frequency component signal;
a first early reflected sound generation means for supplying the second pair of high frequency speakers; a second means for generating an early reflected sound signal from the midrange component signal and supplying the signal to the second pair of midrange speakers; The present invention is characterized by comprising an early reflected sound reproduction means and a fourth delay means for delaying the mid-range signal and supplying the delayed signal to the center speaker.

Furthermore, the third invention of the present application is the apparatus of the second invention,
The present invention is characterized by comprising a pair of bass frequency speakers installed at the bottom of the door of the vehicle interior, and transmission frequency characteristic correction means for correcting the bass component signal.

Furthermore, the fourth invention of the present application is the device of the third invention, which includes a pair of mid-range speakers installed on the left and right sides of the front of the vehicle compartment;
The present invention is characterized by comprising transmission frequency characteristic correction means for correcting the midrange component signal.

[Operations] In the present invention, the direct sound is converted into a low frequency component (for example, 20082
The transmission frequency characteristics are prevented from changing due to the number of passengers on board by separating the frequency range into three bands: a mid-range component (for example, below 5 kHz), and a high-frequency range component (for example, 5 kHz or above).

In addition, the speakers that reflect high frequency components are reflected off the windshield or side glass to increase the sense of spaciousness.

Furthermore, the arrival time of the sound output from each speaker is adjusted so that the bass, middle, and high frequency components reach both ears of the listener at the same time. The level and time of the sound reaching both ears of the listener is also adjusted to correct the localization of the midrange sound output from the left and right speakers.

[Example] First, an overview of the present invention will be explained.

In the present invention, the direct sound is a low frequency component of 200 Hz or less,
By separating the frequency band into three bands: a mid-range component below 5 kHz, a high-frequency range component above 5 Hz, changes in the transmission frequency characteristics due to occupants are prevented.

Since the bass frequency components have long wavelengths and are nearly omnidirectional, they are radiated from the door near the listener's feet, while the mid-high frequency components, which have an important effect on sound image localization, are emitted from the instrument panel on the listener's side and the instrument panel. A speaker is installed to emit light.

In addition, the speakers emitting high frequency components are reflected off the windshield, side glass, etc. to increase the sense of spaciousness.

Furthermore, the arrival time of the sound output from each speaker is adjusted so that the bass, midrange, and treble components reach both ears of the listener at the same time.

The level and time of the sound reaching both ears of the listener is also adjusted to correct the localization of the sound output from the left and right speakers in the middle and high frequency range.

From the side of the listener, a reflected sound is output with a certain time delay in response to the mid-range sound radiated from in front of the listener.
This increases the sense of lateral expansion.

Furthermore, in order to increase the sense of spaciousness in the vertical direction, reflected sound in the high frequency range is radiated near the listener's head. As a result, sound image localization and spaciousness can be adjusted independently.

A speaker is installed at the rear that outputs low frequency components of 100Hz or less, producing powerful sound. Additionally, speakers have been installed that emit sounds over 200 ratio as reverberant sound, creating a sound field full of pleasant reverberation.

Here, since it is almost impossible to specify the position of the sound wave in the low-frequency component of 100 Hz or less, the sound field is synthesized with the low-frequency sound coming from the front even at the rear, and a powerful sound field is formed.

Hereinafter, embodiments of the present invention will be explained in detail with reference to five drawings.

FIG. 1 shows an embodiment of the in-vehicle audio device according to the present invention, and only the left channel is shown in detail, but a device with a similar configuration for the right channel is provided within the dotted line.

In the figure, 1 is the left signal from the sound source, 2 is the network filter, 3 is the high pass filter (HPF), 4 is the band pass filter (BPF), and 5 is the low pass filter (LP
F), 6 to 13 are attenuators, 14.15 are equalizers, 16 to 18 are initial delay circuits, 19 to 22 are delay circuits, 23 is a high pass filter (HPF), 24 is a low pass filter (LPF), 25 is a reverberation sound generation circuit, 26 is an output terminal to the side window tweeter, 27 is an output terminal to the ceiling tweeter, 28 is an output terminal to the instrument panel speaker, and 29 is an output terminal to the upper door speaker. , 30 is an output terminal to the center speaker, 31 is an output terminal to the lower door speaker, 32 is an output terminal to the super woofer, 33 is an output terminal to the rear speaker, and ADD, , ADD are adder circuits.

2(a) and (b) show an example of the speaker arrangement of the acoustic device according to the present invention, in which 26.36 is a side window tweeter, 37.37' is a ceiling tweeter, and 38.38' is a ceiling tweeter. Instrument panel speakers, 39.39' are upper door speakers, 40 are center speakers, 41.41' are lower door speakers, 42 are super woofers, and 43.43' are rear speakers.

Next, the overall signal flow in the embodiment shown in FIG. 1 will be explained, and then the operation of each part will be explained in detail.

In the left channel section of FIG. 1, the left signal 1 is the HP F 3, B P F, 4,
They are added to the LPF 5 and the attenuator 13, respectively. )
The output signal of i P F 3 is output via the attenuator 6 and delay circuit 19 to an output terminal 26 to the tweeter, and is also output via the attenuator 7 and the initial delay circuit 16 to an output terminal 27 to the tweeter 27.

The output signal of the BPF 4 is outputted to the output terminal 29 for the instrument panel speaker via the equalizer 14, attenuator 8 and delay circuit 2o, and is also sent to the upper door speaker via the attenuator 9, HPF 23 and initial delay circuit 17. It is output to the output terminal 29 of. B
The output signal of PF4 is also added to the right signal by an adder circuit ADD, and is then added to the right signal by an attenuator 10 and a delay circuit 21.
The signal is output to the output terminal 30 to the center speaker.

Moreover, the output signal of LPF5 is an adder circuit ADD.

The signal is added to the right signal and outputted to the output terminal 31 for the lower door speaker via the attenuator 11, equalizer 15 and delay circuit 22, and output terminal 3 to the super woofer via the attenuator 12 and LPF 24.
2 is output.

Furthermore, the output signal of the attenuator 13 is output via the initial delay circuit 18 and the reverberation sound generation circuit 25 to an output terminal 33 for the rear speaker.

The above signal flow is the same for the right channel section.

The details of the operation of each part along the above-mentioned signal flow are as follows.

(1) Network filter 2 The cutoff frequency is 5 for high-pass filter 3,
The band pass filter 4 outputs a frequency of 200 Hz to 5, and the low pass filter 5 outputs a frequency of 200 Hz.

■Full-range speakers are common in vehicle interiors. The reason for this is that the places where speakers can be installed are limited, and it is difficult to install speakers with large diameters. However, when a full-range speaker is installed in a door with an instrument panel, frequency components in the middle and high ranges are affected by the directivity of the speaker due to its placement by the listener and passenger.

Therefore, it is desirable to place a speaker for low frequency reproduction below the listener, etc., and a speaker for mid-high frequency reproduction near the ear level of the listener (it is the mid-high frequency component that contributes to sound image localization). (The speakers that emit these sounds are relatively stable in their localization within the horizontal plane.) 6 Furthermore, the sound waves are divided into three frequency bands so that the emitted sound waves reach both ears of the listener at the same time. , time correction is performed by a delay circuit to be described later.

By dividing the 0 frequency band into 3 bands, the transmission frequency characteristics in the vehicle interior can be adjusted appropriately by setting each speaker output level, speaker placement, and crossover frequency.
Flat characteristics can be achieved without using an equalizer.

Furthermore, it can also function as a three-band equalizer depending on the output level of each speaker.

Here, the cutoff frequency of the bandpass filter is 5kl.
(A Z low-pass a filter may also be used. In this case, the bass range characteristics are added, the bass range energy increases, and the sense of force is increased.

(2) Delay circuits 19 to 22 are configured to be variable with a resolution of 0.1 ms.

■Perform time correction so that the sounds emitted from the low-range, mid-range, and high-range speakers reach the listener's ears at the same time.

■The frequency band that is important for sound image localization is the middle and high frequency components. Therefore, by controlling the arrival time difference between those sounds that reach the listener, it is possible to localize the sound image at the front center.

(3) Equalizer 14.15 ■In the middle and high frequency bands important for sound image localization, the transmission frequency characteristics of both ears are affected by the speaker placement and the asymmetry of the listener. In particular, since the frequency component in the mid-range frequency band changes drastically, the equalizer 14 corrects it in order to flatten the transmission characteristics in this mid-range frequency band.

■Since the interior of a vehicle is surrounded by glass surfaces, the environment is such that standing waves are likely to occur in low frequency components. Low-frequency standing waves are not preferred because they do not give the audible impression that bass sounds are muffled.

Therefore, in order to suppress the peak caused by this standing wave, the equalizer 15 corrects it.

(4) Initial delay circuits 16 to 18 The initial reflected sound is a reflected sound necessary to realize a natural sense of spaciousness. When direct sound and early reflected sound are emitted from the same speaker, disturbances occur in the transmission frequency characteristics. Therefore, a sub-speaker is required to radiate early reflected sound.

■The reason for emitting early reflected sound from near the ceiling is to create a sense of vertical expansion.

(2) The reason why the early reflected sound is emitted from the door speaker is that the early reflected sound from a direction of 60'' to 90° gives the listener the most sense of lateral expansion.

(5) Low Pass Filter 24 In order to reproduce crisp bass sounds among low frequency components, components of 1oot (2 or less) are important.

Moreover, below 1oOHz is a component in which the position of the sound source cannot be felt. Furthermore, the sharpness can be changed by the slope of this low-pass filter.

(6) Reverberant sound generation circuit 25 Reverberation is the feeling of a sound remaining pleasantly in the ear.

To this end, it is important to consider human auditory characteristics when constructing a system. There are also ``pleasant reverberations'' and ``unpleasant reverberations'' in the sense of reverberation.

Since the volume inside the car is small, there is almost no reverberation. The reverberation characteristics of concert halls and the like have frequency characteristics, and it seems that the frequency characteristics are constant or the low frequency band is slightly longer.

In a car, booming of low frequency components is likely to occur, so it is desirable that the reverberation characteristics be constant with respect to frequency.

FIG. 3 shows an example of the initial delay circuits 16 to 19 in FIG. 1, that is, an early reflection sound generation circuit, and FIG.
Figure 2 shows in-panel sputtering that is not produced by the circuit shown. In Fig. 3, R1-R1 is a variable resistor, τ1-τ
, are delay circuits, and AD, ~AD are adder circuits.

FIG. 5 shows the configuration of an example of the reverberation sound generation circuit 25 shown in FIG. In FIG. 5, A1 to A.

is an adder, τ, ~τ are delay circuits, g, ~g4 are feedback amplifiers, and k1 ~ are coefficient multipliers.

In the embodiments described above, various acoustic modes can be realized by varying the delay amount of the delay circuit, the cutoff frequency and attenuation amount of each filter, the shape of the initial delay circuit, and the amount of reverberation.

These can be easily realized by combining a DSP (digital signal processor) and a microcomputer.

According to the embodiment of the present invention described above, the following effects can be achieved.

■ Localization correction Although the speaker arrangement inside the vehicle is asymmetrical with respect to the listener, by dividing the speaker band into three bands, localization correction is possible without impairing the stereo feeling.

■Flat transmission frequency - Conventionally, transmission characteristics were corrected using an equalizer, but by dividing the speaker band into three bands, it is now possible to achieve relatively flat transmission characteristics. By correcting with an equalizer, more accurate correction can be performed.

■ Crisp bass reproduction By reproducing corrected bass from the door speakers and reproducing bass with a ratio of less than 100 from the rear, crisp bass reproduction can be achieved.

■Front localization: Front localization can be achieved by reproducing mid-high frequency components from speakers installed on the instrument panel.

■Setting each sound field mode: For example, in a network filter, if you replace the bandpass filter that reproduces mid-high frequency components with a low-pass filter, the low-frequency components of the door and the low-frequency components emitted from the instrument panel speakers will be added. This will output more bass. This is an important mode because driving conditions are likely to be masked by low or noisy sounds.

In this way, each sound field mode can be set by changing the parameters within the system. This can be achieved by using DSP.

[Effects of the Invention] As described above, according to the present invention, in the vehicle interior,
It is possible to achieve optimal acoustic conditions and create a comfortable sound field for listeners.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of a vehicle-mounted audio device according to the present invention, FIG. 2 is a diagram showing an example of speaker arrangement in a vehicle interior, and FIG. 3 is a configuration of an example of the initial delay circuit of FIG. 1. 4 is an output impulse pattern diagram of FIG. 3, and FIG. 5 is a configuration diagram of an example of a reverberant sound generation circuit. 2...Network filter, 3...
...High pass filter, 4...Band pass filter, 5...Low pass filter 5,
16-18 ・-・--Initial delay circuit, ■9-22
...Delay circuit. Figure 2 Figure 3 Figure 4 0 τ1τ2τ3

Claims (1)

[Scope of Claims] 1. A pair of high-frequency range speakers arranged at least on the front left and right sides of the vehicle interior facing the side glass, a pair of mid-range speakers arranged on the front left and right sides of the vehicle interior, respectively; a pair of low-frequency speakers placed on the left and right doors of the room, and a signal separation means for separating a signal from a sound source into at least a low-frequency component signal, a mid-range component signal, and a high-frequency component signal;
a first delaying means for delaying the bass frequency component signal and supplying it to the bass speaker pair; a second delaying means for delaying the midrange component signal and supplying the delayed midrange component signal to the midrange speaker pair; A vehicle-mounted audio device comprising: a third delay means for delaying the high frequency component signal and supplying the delayed high frequency component signal to the high frequency speaker pair. 2. A second pair of treble-range speakers arranged on the upper left and right sides of the vehicle interior, a second pair of mid-range speakers arranged above the left and right doors of the vehicle interior, and a second pair of mid-range speakers located at the front of the vehicle interior. a center speaker disposed in a central portion facing the windshield; and a first early reflected sound generation means for generating an early reflected sound signal from the high frequency component signal and supplying the generated early reflected sound signal to the second high frequency speaker pair. , a second early reflected sound reproducing means for generating an early reflected sound signal from the midrange component signal and supplying it to the second pair of midrange speakers; and a second early reflected sound reproduction means for delaying the midrange signal and supplying it to the center speaker. 4. The vehicle-mounted audio device according to claim 1, further comprising a delay means. 3. The vehicle-mounted acoustic device according to claim 2, further comprising a pair of low-frequency speakers installed at the bottom of the door of the vehicle interior, and a transmission frequency characteristic correction means for correcting the low-frequency component signal. Device. 4. A pair of mid-range speakers installed on the left and right sides of the front of the vehicle,
4. The vehicle-mounted audio device according to claim 3, further comprising transmission frequency characteristic correction means for correcting said midrange component signal.