JP2514143Y2 - In-vehicle sound field correction device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an on-vehicle sound field correction device, and more particularly to an audio supplied to a speaker installed corresponding to a seat in a vehicle compartment to correct acoustic characteristics in the vehicle compartment. The present invention relates to an in-vehicle sound field correction device that corrects a signal.

Background Art The acoustic characteristics of a vehicle interior are unique because the sound field is surrounded by a reflective surface such as glass and towboard and a sound absorbing surface such as a seat, and the sound field space is narrow. Have a pattern. Moreover, the front seats are located approximately in the center of the passenger compartment and the rear seats are located in the rear of the passenger compartment.The acoustic conditions are different, so the paths and temporal densities of the reflected waves reaching both seats, the direct waves and the reflected waves, or The arrival times based on the difference in the stroke difference between the waves are different, so that acoustic characteristics such as sound pressure frequency characteristics and sound wave phase characteristics are significantly different in both seats. An example of sound pressure frequency characteristics is shown in FIGS. 1A and 1B, and FIG. 1A shows sound pressure frequency characteristics in the front seat when front sound sources (speakers) are installed on the left and right of the front door. (B) shows the sound pressure frequency characteristics in the rear seat when the rear sound source is installed on the parcel tray.

Therefore, even if a speaker unit having good characteristics in an anechoic room is installed in the vehicle compartment, it is impossible to obtain a flat frequency characteristic in the vehicle compartment. The disturbance of the frequency characteristic is corrected by the frequency characteristic changing means inserted in the.

FIG. 2 shows an example of the configuration of the reproduction system in the on-vehicle audio device. In the figure, an audio signal from a signal source 1 such as a tuner or a cassette deck is amplified by an amplifier 2 and supplied to a frequency characteristic amplifier 3. The output of the amplifier 3 is power-amplified by the speaker drive amplifier 4 and then supplied to the speaker 5 as a speaker drive signal.

In such a configuration, the audio signal from the signal source 1 is amplified by the amplifier 2 as a signal having a normal frequency characteristic, and is amplified by the frequency characteristic variable amplifier 3 such as the graphic equalizer and the bass treble tone control at the next stage. That is, the speaker drive signal is adjusted to the reproduction frequency characteristic of.

In such an acoustic system, a sound wave radiated from the speaker 5 reaches a predetermined listening point 6 in the sound field shown in FIG. 3 by way of example, a direct wave as shown by a solid line 7 and a vehicle as shown by a dotted line 8. There is a path due to the reflected wave from the interior wall. In this case, at the listening point 6, peaks or dips occur at a certain frequency due to mutual interference between the direct wave and the reflected wave, and the frequency characteristic at the listening point 6 is disturbed. The variable frequency characteristic amplifier 3 is for correcting the disturbance of the frequency characteristic.

However, since the disturbance of the frequency characteristics due to the interference of the reflected waves is caused by the difference in the reach distances of the two sound waves, the peak and dip frequencies change when the installation state of the device or the listening position changes. Therefore, when trying to correct it by the graphic equalizer, a large number of circuits are required, resulting in high cost and very difficult adjustment. Further, it is impossible to correct peaks and dips with a device having only the bass treble tone control function.

Further, in the passenger compartment, the high frequency characteristics at the listening point are deteriorated due to sound absorption by the interior material and the speaker mounting position. This is because the attenuation rate in the passenger compartment increases as the frequency increases.
This is because the sound absorption rate increases. In particular, the front seat has a larger decrease in high frequency range than the rear seat. The reason why the lower high range in the rear seats is small is because the rear wind is reflective.

Further, in the passenger compartment, the audible frequency characteristic also changes due to a masking phenomenon caused by the running noise of the vehicle. Fig. 4 shows the spectrum of vehicle interior noise depending on the road conditions and running speed.

As described above, the acoustic characteristics in the passenger compartment change variously depending on the listening position (seating position), the interior material, the masking phenomenon due to running noise, and the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is an object of the present invention to provide an in-vehicle sound field correction device that can always obtain good acoustic characteristics regardless of changes in the listening position and the number of passengers. To aim.

The in-vehicle sound field correction device according to the present invention has a pair of left and right front speakers installed corresponding to the front seats of the passenger compartment and a pair of left and right rear speakers installed on the parcel tray corresponding to the rear seats. An in-vehicle sound field correction device that corrects acoustic characteristics in a vehicle compartment by correcting an audio signal to be supplied, the input means inputting a seating situation in each of the front seat and the rear seat, and the input means. If there are a plurality of occupants in the front seat according to the input information from the first seat, the first correction means for increasing the sound pressure level in the high frequency range of the front speaker, and the rear seat according to the input information from the input means. When there are multiple occupants, the pair of output levels of the rear speaker are the same, while when there is only one occupant, the output level of the speaker closer to the seat on which the occupant is seated is the output level of the other speaker. It is characterized in that a second correction means for attenuating also.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

The on-vehicle audio device according to the present invention includes, for example, four left and right speakers installed in the vehicle compartment corresponding to the front seat and the rear seat, respectively. A pair of speakers for the rear seats are installed on the left and right rear doors or on the parcel tray on the door or dashboard.

In FIG. 5, the audio signal from the signal source is the first
Through the high-frequency correction circuit 10 and the running masking correction circuit 11 of the front-seat speaker correction circuit 12, the rear-seat speaker correction circuit 13, and the low-frequency speaker low-pass filter 14.
Is supplied to. The first high-frequency correction circuit 10 is a boost circuit that corrects a decrease in the energy response peculiar to the speaker in the high frequency range and a decrease in the energy response at the average sound absorption coefficient in the vehicle interior. The running masking correction circuit 11 corrects the audible frequency characteristic (see FIG. 4) that changes due to a masking phenomenon caused by running noise of the vehicle.

The correction circuit 12 for the front seat and the correction circuit 13 for the rear seat are
Since the configuration is basically the same, the correction circuit 12 for the front seat will be mainly described below. Both correction circuits 12, 13
Both have two symmetrical signal systems corresponding to a pair of left and right speakers, and only one of these signal systems will be described.

The second high-frequency correction circuit 15L in the correction circuit 12 is a boost circuit (a so-called tone control circuit) that corrects the high-frequency characteristics that vary depending on the vehicle type, such as the sound absorption coefficient of the vehicle interior due to differences in sound absorbing materials. is there. This second
The high-frequency correction circuit 15L and the first high-frequency correction circuit 10 described above correct the frequency characteristics in the vehicle compartment to be flat over almost the entire area.

The correction circuit 12 also has an occupant number correction circuit 16L for correcting the mid-high range of the speaker sound pressure level in accordance with the occupant number information output from the input means 30. It has a peak dip correction circuit 17L that corrects the swell of the frequency characteristic generated by the interference between the direct wave from the speaker and the reflected wave in the room. The peak / dip correction circuit 17L is a bandpass filter 18L that passes the band where the peak and dip of the input signal pass, and a delay circuit that delays the signal so that the output of this filter becomes the peak and dip frequency.
19L, a level adjustment circuit 20L that corrects the peak and dip levels, a phase inverter 21L that inverts the phase of the level-adjusted signal, and an addition that adds the outputs of the inverter 21L and the passenger number correspondence correction circuit 16L. With a container 22L. The output of the adder 22L becomes a speaker drive signal of the L (left) channel as an output signal of the correction circuit 12 via the variable gain device 23L and the power amplifier 24L.

First and second high frequency correction circuits 10 and 15L, running masking correction circuit 11, and peak dip correction circuit 17L
Is not the main characteristic part of the present invention, so its action and
Detailed description of the operation is omitted.

Next, the number-of-occupants correction circuit 16L that corrects the output characteristics of the speaker according to the change in the number of occupants will be described.

First, when a pair of speakers for the front seat is installed on the front door, it is assumed that the acoustic characteristics are in the optimum state when the occupant alone (for example, only the driver) listens to the sound. In this state, when the number of listeners increases and multiple occupants are lined up in a horizontal row, the increased occupants interfere with the radiated sound from the nearby speakers, and humans have a high sound absorption coefficient especially in the middle and high frequencies. Therefore, as shown in FIG. 6, due to the increase in the number of passengers, the level in the mid-high range of approximately 1 KHz or more is lowered by about 1 to 2 dB from the optimum listening level (solid line (a)) up to that point as shown by the broken line (b). Will be lost. Therefore, the correction circuit 16L for the number of passengers corrects the sound pressure level of the speaker to be increased by about 1 to 2 dB in the middle-high range of approximately 1 KHz or more in response to the information input indicating that there are a plurality of passengers output from the input means 30. To do. The correction of the middle and high frequencies is performed not only on the L channel but also on the R channel at the same time. That is, the occupant number correction circuit 16R operates in the same manner as the occupant number correction circuit 16L according to the output of the input means 30. As a result, a flat frequency characteristic can always be obtained even if the number of passengers changes.

Number of passengers corresponding correction circuit 16L (16R), for example, as shown in FIG. 7, the differential amplifier 16A, resistors R _7, R _8, capacitor
It is composed of C ₃ , a transistor Q ₁ and, for example, two switches S ₁ and S ₂ corresponding to the seat. In such a configuration, the transistor Q ₁ is turned on and the frequency characteristic is corrected only when both of the _two switches S ₁ and S ₂ are turned on at the same time. From the input means 30, switch S ₁ ,
A signal for controlling on / off of S ₂ is supplied. The input means 30 will be described later.

If a pair of speakers for the front seats as well as the rear seats are installed on the rear door, the sound pressure level of the speakers can be similarly corrected in the mid-high range of approximately 1 KHz or more according to the change in the number of passengers in the rear seat. Done.

In addition, considering the case where the speaker SP is attached to the front door 43 in the front seat as shown in FIG. 8, the attachment position is generally restricted to the lower part of the door 43 because of the structure of the door. It will be near the feet of the occupants. Therefore, the radiated sound of the speaker closer to the occupant is significantly blocked by the occupant's foot, body and seat, and is attenuated and absorbed. In addition, as shown in FIG. 9, one closer to the occupant (eg, driver) (right front door)
The angle θ ₁ of the line connecting the center of the speaker of (43R) and the listening point (the occupant's ear) with the speaker center line is considerably larger than the angle θ ₂ of the speaker of the opposite door (left front door 43L). . As a result, due to the directional characteristics of the speaker, the sound pressure level of the speaker at the door on the opposite side is relatively high, and the sound image tends to bend in that direction, causing the sound image localization to shift and obtaining good stereo acoustic characteristics. It will not be possible. In order to normalize the sound image localization, the variable gain device 23L or 23R corrects the output level of the speaker closer to the listening point according to the seating information of the occupant output from the input means 30. As a result, the listening level at the listening point becomes substantially the same on the left and right, and good stereo acoustic characteristics can be obtained despite the speaker arrangement that is biased to the left and right with respect to the listening point.

According to the measurement by the inventor of the present application, good results are obtained by increasing the output level of the speaker closer to the listening point by about 2 to 5 dB. If the number of passengers increases and the number of passengers increases, lower the sound pressure level of the speaker near the listening point to restore it, or raise the output level of the speaker farther from the listening point by the same level, and The sound pressure levels of the speakers may be made substantially the same. Variable gain device 23L, 23
As R, a well-known structure can be used, and it is sufficient if the gain can be switched in at least two stages depending on whether the occupant is alone or a plurality of occupants.

On the other hand, considering the case where the speaker SP is installed on the parcel tray 40 as shown in FIG. 8 in the rear seat,
The position of the speaker with respect to the listening point is much closer than in the case of the front seat, and since the speaker is oriented toward the listening point, the sound pressure level of the relatively nearer speaker is higher and the sound image is in that direction. It will be hard. Therefore,
Contrary to the case of the front seat, by lowering the output level of the speaker closer to the listening point with the variable gain device 25L or 25R, the sound image localization becomes normal and good stereo acoustic characteristics can be obtained. .

Variable gain device 25L (25R), for example, as shown in FIG. 10, the differential amplifier 25A, transistors Q _2, Q _3, the resistor R ₉ to R ₁₂
And two switches S ₃ and S ₄ corresponding to the seat. In this configuration, the circuit is L
Channel side variable gain device 25L and switch S ₃
Is for the left seat and the switch S ₄ is for the right seat, respectively, and when the occupant is seated only in the left seat, the switch S ₃ is turned on according to the seating information from the input means 30. As a result, the transistor Q ₃ is turned on and Q ₂ is turned off, so that the output level of only the speaker on the L channel side is reduced. Also, when the occupant also sits in the right seat, the switch S ₄ is also turned on, so that the transistor Q ₃ is turned off and Q ₂ is turned on, and the output level of the speaker on the L channel side is returned to the original level. The sound pressure levels of the left and right speakers are substantially the same. According to the measurement by the inventor of the present application, good results are obtained by lowering the level within the range of 2 to 5 dB. If there are multiple occupants in the rear seats, the output level of the speaker that has been lowered may be restored as described above, but the output level of the speaker that is farther from the listening point may be lowered. By doing so, the sound pressure levels of the left and right speakers may be made substantially the same. Further, when the occupant is seated in the center of the rear seat, the acoustic left-right balance is maintained, and therefore, it is not necessary to make a correction.

On the front seat side, the second high frequency correction circuit 15L (15
R) and the correction circuit 16L (16R) for the number of passengers described in FIG.
Although the circuit configuration of and is separately, as shown in FIG.
By using the two differential amplifiers 15A (or 16A) also as an integrated circuit configuration, it is possible to reduce the cost and simplify the circuit configuration due to the reduction of parts. Also, on the rear seat side, the variable gain device 25L (25R) described in FIG. 10 also has a single circuit configuration, but as shown in FIG.
The same effect as the above effect can be obtained by combining 15A (or 25A) and forming a circuit configuration integrated with the second high frequency correction circuit.

Next, the input means 30 will be described. The input means 30 is for inputting the number of passengers in each of the front seats and the rear seats. For example, by arranging a plurality of switches in the operation unit corresponding to each seat and manually operating these switches. It may be configured to input the sitting situation by
Further, each seat may be provided with a switch that operates when an occupant is seated, and the seating status may be automatically input.

The information input by the input unit 30, that is, the seating status of each seat is displayed by the display unit 31 including a plurality of display elements such as light emitting diodes provided corresponding to each seat. The respective display elements in the display means 31 are arranged, for example, in the same manner as the seats so that the passenger arrangement can be seen at a glance. The display means 31 displays the seating situation by, for example, changing the hue, blinking or changing the brightness. Its concrete structure is shown in FIGS. 13 to 15. Display means for displaying by changing hue
As shown in FIG. 13, for example, 31A is a drive circuit 32 that operates according to input information from the input means 30 and two light emitting diodes D ₁ and D ₁ provided for one seat and having different emission colors from each other. _2, a resistor R ₁₃ to R ₁₅ and transistor Q _4, usually the output of the drive circuit 32 is emitting light-emitting diodes D ₂ by a low level, the corresponding switch is turned on in the input unit 30, The output of the drive circuit 32 becomes high level and the light emitting diode D ₁ emits light, and at the same time, the transistor Q ₄ is turned on to turn off the light emitting diode D ₂ . For example, as shown in FIG. 14, the display means 31B which makes a blinking display is composed of a multivibrator 33 triggered by the output of the input means 30, a resistor R ₁₆ and a light emitting diode D _3, and emits light at a cycle determined by the multivibrator 33. Performs the action of flushing the diode D ₃ . Display means 31C which forms a display by the luminance change, for example as shown in FIG. 15, the transistors Q ₅ forming the ON / OFF operation in response to the output of the input means 30 is supplied through a resistor R _17, the diode D ₄ , which consists of resistors R ₁₈ and R ₁₉ , the transistor Q ₅ is normally in the off state, and a small current determined by the resistors R ₁₈ and R ₁₉ flows through the light emitting diode D ₄ , so that the brightness of the light emitting diode D ₄ is dark. When the transistor Q ₅ is turned on according to the output of the input means 30, the resistor R ₁₉ is bypassed and the current flowing through the light emitting diode D ₄ is increased to brighten its brightness.

Effect As described above, according to the present invention, when there are a plurality of occupants in the front seat, the sound pressure level in the high range of the pair of speakers installed corresponding to the seats is increased, and the rear seats are increased. When there are multiple occupants, the output levels of the pair of speakers installed in the parcel tray corresponding to the seats are set to be approximately the same, and when there is only one occupant, the speaker closer to the seat on which the occupant is seated Since the output level is attenuated, the sound quality is corrected in the front seats in the passenger compartment, the sound image localization and the sound volume are corrected in the rear seats, and the sound quality is always good regardless of the seating position and the number of passengers. An on-vehicle sound field correction device capable of obtaining characteristics can be obtained.

[Brief description of drawings]

FIG. 1 (A) is a sound pressure frequency characteristic in a front seat in a vehicle compartment, (B) is a sound pressure frequency characteristic in a rear seat, and FIG. 2 is a configuration diagram showing an example of a reproduction system of an in-vehicle audio device, FIG. Fig. 4 is a diagram showing an example of direct waves and reflected waves in a sound field, Fig. 4 is a diagram showing a spectrum of vehicle interior noise according to road conditions and traveling speed, and Fig. 5 is one embodiment of the present invention. FIG. 6 is a block diagram showing an example, FIG. 6 is a frequency characteristic diagram showing a state where the high frequency band level is lowered due to an increase in passengers, and FIG.
FIG. 8 is a circuit diagram of an example of a correction circuit 16L (16R) corresponding to the number of passengers in the figure, FIG. 8 is a diagram showing speaker mounting positions in the passenger compartment, and FIG. 9 is a pair of left and right speakers mounted on the front door and listening points. Fig. 10 shows the positional relationship of Fig.
Circuit diagram showing an example of the variable gain device 25L (25R) in the figure,
FIG. 11 is a circuit diagram of an example in which the second high-frequency correction circuit on the front seat side and the correction circuit corresponding to the number of passengers are integrally configured in FIG. 5, and FIG. 12 is the second high-frequency correction circuit on the rear seat side. And a circuit diagram of an example in which the variable gain device is integrally configured, FIGS.
FIG. 15 is a circuit diagram showing a specific configuration of the display means in FIG. Explanation of symbols of main parts 10 …… First high frequency correction circuit 11 …… Running masking correction circuit 12 …… Speaker correction circuit for front seat 13 …… Speaker correction circuit for rear seat 15L, 15R …… Second High frequency correction circuit 16L, 16R …… Correction circuit for occupant number 17L, 17R …… Peak / dip correction circuit 23L, 23R, 25L, 25R …… Variable gain unit 30 …… Input means, 31 …… Display means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinjiro Kato 25-1 Nishimachi, Yamada character, Kawagoe City, Daiji Pioneer Co., Ltd. Kawagoe factory (72) Yoshio Sasaki 1-25 Nishimachi, Kawagoe city, Nishimachi Pioneer shares Company Kawagoe factory (72) Inventor Makoto Kotaka 25-1, Nishimachi, Yamada, Kawagoe City Pioneer Co., Ltd. Kawagoe factory (72) Inventor Takeshi Sato 25, Nishidamachi, Yamago, Kawagoe city Pioneer Corporation Kawagoe factory (56) References JP-A-58-138200 (JP, A)

Claims (1)

(57) [Scope of utility model registration request] 1. An audio signal supplied to a pair of left and right front speakers installed corresponding to a front seat in a passenger compartment and a pair of left and right rear speakers installed in a parcel tray corresponding to a rear seat are corrected. An on-vehicle sound field correction device that corrects the acoustic characteristics of the vehicle interior by performing inputting means for inputting the seating situation in each of the front seat and the rear seat, and in accordance with input information by the input means. When there are a plurality of occupants in the front seat, there are a plurality of occupants in the rear seat according to the first correction means for increasing the sound pressure level in the high frequency range of the front speaker and the input information from the input means. When the pair of output levels of the rear side speakers are the same while the output level of the speaker closer to the seat on which the occupant is sitting is attenuated more than the output level of the other speaker in the case of a single speaker, a second auxiliary device is provided. Automotive sound field correction apparatus characterized by comprising a means.