JP2926679B2 - On-board audio equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in- vehicle sound for automatically adjusting a volume and a dynamic range so that music and the like can be heard without being affected by the noise even when the vehicle is running. It concerns the device .

[0002]

2. Description of the Related Art Heretofore, there has been an example in which noise is collected by a microphone and a reproduction sound volume is adjusted by a noise sound pressure, or a reproduction sound volume is adjusted by estimating a noise sound pressure from an output signal of a vehicle speed sensor. The conventional example using a microphone has an advantage that the fluctuating noise itself can be collected by the microphone, but has a disadvantage that the noise cannot be detected when the reproduction volume is large because the reproduction sound of music is mixed into the microphone.

In a conventional example using a vehicle speed sensor,
The noise sound pressure corresponding to the vehicle speed is estimated from the output signal of the vehicle speed sensor, and the reproduction volume is adjusted. Fig. 9 shows Tokiko 52
It is a functional block diagram showing an example of the conventional in-vehicle sound reproducer shown in -28003. In the figure, 31 is a pulse generator A which generates a pulse in proportion to the vehicle speed, 32
Is a voltage control unit that generates a control signal from the vehicle speed pulse, 33 is a volume control circuit that controls the volume, 34 is a preamplifier, 35 is a main amplifier that amplifies voltage, 36 is a tuner,
37 is a magnetic head such as a cassette deck, 38 is a speaker, 39 is a pulse generator B for generating a pulse corresponding to the engine speed, and 40 is a voltage control circuit for generating a control signal from the rotation pulse. In this conventional example, volume control is performed using two pulse generators.

Next, the operation will be described. The pulse generated by the pulse generator A31 that generates a number of pulses proportional to the number of rotations of the vehicle wheels is supplied to the voltage control circuit 32. The voltage control circuit 32 generates a DC voltage proportional to the number of pulses, and the DC voltage is supplied to a volume control circuit 33. Further, the pulse generator B39 that generates a pulse corresponding to the engine speed generates a number of pulses proportional to the engine speed. The generated pulse is applied to the voltage control circuit 3
2, the voltage control circuit 40 counts the pulses and generates a DC voltage proportional to the number of pulses. The DC voltage of the voltage control circuit 40 is supplied to the volume control circuit 33. The volume control circuit 33 controls the voltage of the audio signal supplied to the main amplifier 35 by the DC voltage output from the two voltage control circuits 32 and 40.
For example, since there is a positive correlation between the engine speed or the vehicle speed and the noise generated during traveling, the volume control circuit 33 increases the audio signal voltage when the engine speed or the vehicle speed increases. Therefore, the reproduced sound radiated from the speaker 38 increases.

When the engine speed and the vehicle speed decrease in an attempt to stop the vehicle, the DC voltage input to the volume control circuit 33 decreases, and the volume control circuit 33 decreases the voltage of the audio signal. Therefore, the reproduced sound radiated from the speaker 38 decreases. As described above, the sound volume is controlled by utilizing the fact that there is a positive correlation between the engine speed and the vehicle speed and the noise during traveling.

[0006] However, it is known that the noise value differs depending on the road surface condition of the road on which the vehicle is traveling even when the vehicle speed during traveling is the same. According to “Acoustic Engineering Noise and Vibration” (Corona), the relationship between road surface roughness and noise level is shown. FIG. 8 shows a relationship diagram. In the figure, the horizontal axis represents the roughness of the road surface, and the vertical axis represents the noise level. The difference in the noise level when the vehicle travels on roads with different road surface roughness at a traveling speed of 80 km / h can be read.

Taking a passenger car as an example, a road surface roughness of 0.1 m
m, the noise is 71.5 dbA, but the road surface roughness is 1.0 m
m, the noise is 79 dbA, and when the road surface is rough, about 7.
Increase by 5 dbA. When the noise level increases by 7.5 dbA, a considerable portion of the music being played becomes inaudible, and the volume must be readjusted. Further, as in the examples of other automobiles I to I in FIG. 8, since the amount of fluctuation of the noise differs depending on the vehicle type , an error may occur when estimating the noise from the vehicle speed or the engine speed.

[0008]

Since the conventional on-vehicle sound reproducing apparatus is configured as described above, it is difficult to detect noise with a microphone when the volume of music reproduction is high, and the vehicle speed is low. Sensors cannot adapt to differences in noise level due to different road conditions,
There is a problem that an error occurs in the estimation of.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can automatically adjust the volume according to the noise level regardless of the music playback volume, and can correctly adjust the volume even when the road surface condition changes. It is an object of the present invention to provide an in-vehicle acoustic device capable of adjusting a volume according to a noise amount.

[0010] vehicle acoustic apparatus according to the present invention, in that so as to adjust in accordance with the noise vehicles the output of the acoustic apparatus mounted on a vehicle, a microphone for detecting the noise in the passenger compartment of the vehicle, vehicles a vehicle speed sensor for detecting the speed amplifier produces a noise output corresponding to the vehicle speed based on the output of the vehicle speed sensor, output and micro, sign inversion of the amplifier
A first adder that adds the output of the
The output of the hold circuit that holds the output potential of the first adder
A second adder for adding the bets, comparator for comparing the outputs of the acoustic <br/> device microphones are on-off controlled by the output of the comparator <br/> data, first when on a switch for applying the output of pressurized <br/> adder to-hold circuit,
When the output level of the sound device is low , the output of the first adder
Audio device according to the output obtained by adding the output of the second adder
When the output level of the audio device is high , the gain of the audio device is adjusted according to the output of the second adder.
The amplification factor for the output is adjusted.

[0011] Also, in those to be adjusted according to the car <br/> noise of both the output of the audio apparatus mounted on a vehicle, vehicle
Microphone for detecting the noise in the passenger compartment of the two, a vehicle speed sensor for detecting the speed of a vehicle, the amplifier produces a noise output corresponding to the vehicle speed based on the output of the vehicle speed sensor, the amplifier
Of the output of the microphone with the sign inverted
First adder, output of amplifier and output potential of first adder
Second addition for adding the output of the hold circuit that holds
Vessel, a comparator for comparing the outputs of the acoustic device of microphones, are on-off controlled by the output of the comparator, a first switch for applying an output of the first adder-hold circuit when turned on, the vehicle speed sensor Output and the first
First differential amplifier, a second differential amplifier for obtaining a difference between the output and the second predetermined value of microphones that of obtaining a difference between the predetermined value,
A divider for obtaining a ratio between the outputs of the first and second differential amplifiers ,
A divider and comparator first switch synchronism with by the output OFF control, the output of the divide unit when on
Is supplied to the amplifier, and a second switch to be equal to the output of the divide unit the amplification factor of the amplifier, when the low output level of the acoustic device, the first adder Output and the second module
The output of the audio device is determined according to the output obtained by adding the output of the arithmetic unit.
Adjust the amplification factor against, when the high output level of the acoustic device, against the output of the acoustic device in accordance with the output of the second adder
In this case, the amplification factor is adjusted.

[0012] is et al. In addition, out of the acoustic device mounted on the vehicle
In those forces to be adjusted according to the noise of the vehicles, a microphone for detecting the noise in the passenger compartment of vehicles, a vehicle speed sensor for detecting the speed of the vehicles, corresponding to the vehicle speed based on the output of the vehicle speed sensor amplifier that produces a noise output that, this
Add the inverted output of the amplifier and the output of the microphone.
The first adder, the output of the amplifier and the output of the first adder.
Second to add the output of the hold circuit that holds the force potential
Adder, a comparator for comparing the outputs of the acoustic device of microphones, car speed divider for obtaining a ratio between outputs of the microphones of the sensor is on-off controlled by the output of the comparator, when on the output of the divide unit is supplied to the amplifier, the switch to be equal to the output of the divide unit the amplification factor of the amplifier is switching control by the output of the switch and comparator, adder of comprising a changeover switch for the power control element of the acoustic device selectively takes out the outputs and Ma Ikuroho <br/> down, when the lower output level of the acoustic device in accordance with the output of the microphones Sound device output
Adjust the gain for the force, at high output level of the acoustic device, to the output of the acoustic device in accordance with the output of the adder
The gain is adjusted.

[0013]

In the noise detection according to the present invention, when the output level of music is low, the sound pickup of the microphone and the output of the vehicle speed sensor are performed.
DOO estimates the amount noise based on, when the output level of the music is great and estimates the amount of noise based on the output of the vehicle speed sensor, to attempt to correct the coefficients of the noise estimation straight line noise microphone detects Things.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, Embodiment 1 of the present invention will be described. In FIG. 1, 1L and 1R are input terminals for left and right stereo signals, respectively, 2 is an adder for converting a stereo signal into a monaural signal, 3 is a main volume that determines a user's listening volume, 4 is a volume / tone control unit, and 5L. 5R, an electronic volume for performing dynamic range compression, 6L, 6R, low-frequency equalizer circuits for increasing low-frequency components, 7L, 7R
Is a volume variable circuit for automatically adjusting the volume, 8L and 8R are power amplifiers, and 9L and 9R are speakers.

A stereo signal reproduced by a head unit such as an LD player or a cassette deck is supplied to an input terminal 1L.
Is input to the 1R, are set to easily listening volume-out hear the main volume 3.

The output of the main volume 3 is input to a sound quality / volume adjuster 4, which performs dynamic range compression and low frequency enhancement volume adjustment in accordance with the noise, and then power amplifier 8L,
Power is amplified by 8R, and sound is radiated into the vehicle cabin by speakers 9L and 9R.

On the other hand, 10 is a vehicle speed sensor that generates a pulse proportional to the vehicle speed, 11 is a frequency-voltage conversion circuit that counts the number of pulses and generates a voltage proportional to the number of pulses, 12
Is a time constant circuit that converts a voltage that fluctuates according to the vehicle speed into a voltage that changes with a predetermined time constant, 13 is an amplifier having an amplification factor K for relating an increase in vehicle speed to an increase in noise, 14 is a noise detection microphone, 15 is a time constant circuit that converts a microphone output voltage that varies unsteadily to a voltage that changes with a predetermined time constant, 16 is a time constant circuit that converts a stereo signal such as music into a voltage that changes with a predetermined time constant, 17 is a comparator for comparing the music voltage with the noise voltage, 18 is a time constant circuit, 19 and 20 are adders, 21 is a switch,
2 is set by a capacitor constituting a hold circuit for holding the DC potential that is set in advance, the voltage N ₀ corresponding to the noise of the vehicle speed 0 km / h.

The operation of noise detection and the operation of adjusting the volume and sound quality according to the amount of noise will be described below. Input terminal 1
The music signals input from L and 1R are added by the adder 2, become a monaural signal, enter the time constant circuit 16, and become a voltage signal that changes with a predetermined time constant. If the volume and the sound quality are greatly changed within a short time, the characteristics of the music are changed, and the sense of incongruity is generated in the sense of hearing. Therefore, it is necessary to change the volume and the sound quality gently. Therefore, it is preferable that the time constant of the time constant circuit 16 is set to change gently at, for example, 200 Hz or less. Then, the output of the time constant circuit 16 is supplied to the comparator 17.

The noise collected by the microphone 14 passes through a time constant circuit 15 having the same time constant as the time constant circuit 16 and becomes a voltage that changes gently and enters a comparator 17.

The comparator 17 compares the music voltage output from the time constant circuit 16 with the microphone voltage output from the time constant circuit 15. Now, if the microphone voltage is sufficiently larger than the music voltage, the output of the comparator 17 becomes High. At this time, the switch 21 is turned on and in a conductive state. At this time, the output of the adder 19 is added.
It becomes plus the outputs of the amplifier 13 of the adder 20, the noise voltage of the microphone is supplied volume and the tone control circuit 4.

In the volume / tone control circuit 4, the output of the adder 19 is output.
If the power increases, the compression ratio of the dynamic range is increased, the low-frequency enhancement ratio is increased, and the volume is further increased. When the output of the adder 19 decreases, the dynamic range compression rate is reduced, the low frequency enhancement rate is reduced, and the sound volume is adjusted to decrease. The time constant circuit 18 is the switch 2
At the time of opening and closing of 1, the output of the adder 19 is given a time constant to make the change gradual. For example, the above change in volume and sound quality is 1d
If the time constant is determined so as to be B / sec, a sense of incongruity hardly occurs during listening.

FIGS. 2 and 3 show an example of volume / sound quality adjustment. FIG. 2 is a diagram showing the relationship between the dynamic range compression amount, the volume increase amount, and the noise. In the figure, the horizontal axis represents the noise value, and the vertical axis represents the dynamic range compression amount and the volume increase amount. When the noise is small, such as when the vehicle is stopped, the dynamic range compression and volume adjustment are not performed. It is set to start. As the noise increases, the amount of compression in the dynamic range is increased. By the compression, the sound pressure of the weak sound portion of the music is increased, so that even if there is noise, the sound can be easily heard.

If the amount of compression in the dynamic range is too large, there is no change in the strength of the music, and the musicality is impaired. Further, since the noise is less likely to take-out a greater becomes the strength clef also heard, for example, in the case of more than noise 70 dB, reducing the amount of compression of about 10 dB, and are set so as to increase the volume of the entire progressively.

FIG. 3 is a diagram showing an example of enhancement of a low frequency band. The horizontal axis noise value and the vertical axis represents the <br/>equalizer's weight, e.g. 50～120Hz. Even when the vehicle is stopped, if the vehicle is idling, noise due to engine rotation is generated. This noise has a characteristic that a low frequency component is large, so that a situation arises in which the low frequency component of the music is difficult to hear at first. As the noise increases, the amount of equalization is increased, and adjustments are made so that the bass components of the music are easier to hear.

If the difference between the microphone voltage and the music voltage is small, the output of the comparator will be low. In this case, since the music output level is large, a music signal is mixed into the microphone, which corresponds to a situation where noise cannot be detected with high accuracy. When the output of the comparator 17 is Low, the switch 21 is opened, and the output of the time constant circuit 15 is cut off. At this time, the noise value estimated from the output of the vehicle speed sensor 10 is supplied to the volume / sound quality adjustment circuit 4 via the accelerator 19 . In the volume / tone control circuit 4, the voltage of the microphone described above is changed according to the estimated noise value corresponding to the vehicle speed.
Automatic adjustment of volume and sound quality is performed in the same manner as when the pressure is sufficiently higher than the pressure .

[0026] As a condition for switching between microphones and a vehicle speed sensor, for example a microphone voltage than the voltage of the music 1
When the output is larger than 0 dB, the output of the comparator 17 is set to Hi.
If gh is less than 10 dB, and is set to Low, the microphone 14 can perform noise detection with sufficient accuracy. .

Next, a method of estimating noise from the output of the vehicle speed sensor and correction of the estimated noise value will be described. In general,
It is known that the vehicle speed and the noise are in a substantially proportional relationship if the vehicle type is the same and the traveling road surface condition is constant. Assuming that the voltage corresponding to the vehicle speed is V and the voltage of the estimated noise value is N, N = kV + N ₀ ... (1) Here, k is the amplification factor of the amplifier 13 in FIG. N ₀ is a voltage corresponding to the noise sound pressure at a vehicle speed of 0 km / h, and is a terminal voltage of the capacitor 22.

The noise estimation operation according to the above equation (1) will be described with reference to FIG. The pulses generated by the vehicle speed sensor 10 are counted by a frequency-voltage conversion circuit 11, converted into a voltage proportional to the vehicle speed, and output. The output voltage is input to the time constant circuit 12, and becomes a voltage signal V that gradually changes with the same time constant as the other time constant circuits 15 and becomes an amplifier 13.
Is input to The amplification factor k of the amplifier 13 can be approximately calculated from the measurement data of the expressway. The voltage signal V is supplied to the amplifier 1
3, the voltage becomes a voltage kV which is amplified at the amplification factor k and is proportional to an increase in noise.

The output voltage kV from the amplifier 13 is added to the adder 1
9 and is added to the terminal voltage N ₀ of the capacitor 22. Since the terminal voltage N ₀ is set in advance to a voltage corresponding to the noise at a vehicle speed of 0 km / h, the output of the adder 19 becomes N in equation (1), and the noise is estimated.

On the other hand, the output voltage kV of the amplifier 13 is input to the adder 20 after sign inversion. The adder 20 adds the output voltage M of the time constant circuit 15 and −kV, and the addition result M−kV enters the switch 21. Switch 21 is o
In the n state, the voltage M-kV is applied to the capacitor 22. When the switch 21 is turned off, the terminal voltage M-kV is held by the capacitor 22.

The noise voltage N _{0 at} the amplification factor k and the vehicle speed of 0 km / h in the equation (1) is approximated by measuring the relationship between vehicle speed and noise when traveling on a highway, and by measuring the noise at a stop. Can be sought.

For example, the relationship between vehicle speed and noise is expected to be as shown in FIG. In the figure, the solid line is an estimated straight line of the noise based on the traveling data of the expressway. When traveling on an expressway, the noise value is calculated by moving on a solid line according to the vehicle speed. In the solid line, the amplification factor k = 0.25 (increase rate per 1 km / h of vehicle speed), and N ₀ = 45 (noise d at 0 km / h of vehicle speed)
B value). The noise changes by 47 to 70 dB while the vehicle speed changes by 0 to 100 km / h.

Now, it is assumed that the noise detecting means is switched from the microphone 14 to the vehicle speed sensor 10 at a vehicle speed of 90 km / h. Assuming that the noise value of the microphone 14 at this time is 67 dB, in FIG. 4, the switching is performed at the point A on the solid line. Thereafter, since the noise is estimated by the equation (1), the estimated noise value changes on the solid line in FIG. 4 according to the vehicle speed. Then, the sound quality / volume adjusting circuit operates according to the estimated noise value. At this point A, there is no error between the noise value of the microphone 14 and the estimated noise value of the vehicle speed sensor, and the automatic adjustment of sound quality and volume is switched smoothly and naturally.

Next, a case where the road surface is rough and the noise sound pressure during traveling is different will be described. When the noise collected by the microphone 14 at a vehicle speed of 60 km / h is 70 dB, this corresponds to the point B in FIG. At this time, between the noise value of the microphone 14 and the estimated noise value of the expressway (point C in FIG. 4 ), 10
An error of dB has occurred. At this point B, the output of the comparator 17 is High, and the microphone 14 performs noise detection.

When the output of the comparator 17 is High,
Since the switch 21 is on, the capacitor 22
Is applied with a terminal voltage M-kV. When the output of the comparator 17 becomes low, the switch 21 is turned off, and the output of the adder 20 is not applied to the capacitor 22. Therefore, the terminal voltage B of the capacitor 22 is maintained at the voltage M-kV immediately before switching. At this time, N _{0 in the} equation (1) for estimating the noise is as follows: N ₀ = M−kV (2) Therefore, the noise is estimated on the new noise estimation line.

In FIG. 4, the estimated straight line is a broken line. Since the dashed line in the figure passes through the point B, no error occurs between the noise value of the microphone 14 and the estimated noise value of the vehicle speed sensor 10. Therefore, automatic adjustment of sound quality and volume is smoothly and naturally switched.

In the above embodiment, the case where the noise estimation is corrected by changing and maintaining the terminal voltage of the capacitor has been described. However, the digital calculation function and the digital control function of the microcomputer or the digital signal processor are not described. It is known to use this to adjust the amplification factor. In this case, the equation (1) is calculated by digital operation,
It will perform noise measurements the volume or switching device with digital control. In addition, using advanced digital multiplication function, the dynamic range can be compressed by changing the coefficient that multiplies the music amplitude value from the time constant circuit,
Low frequency equalization can be realized by a digital filter. The same effect can be obtained by setting the speed or value of changing the coefficient to a predetermined value .

Embodiment 2 A second embodiment will be described with reference to FIG. FIG. 3 shows an example in which the correction is performed by changing both the terminal voltage of the capacitor 22 and the amplification factor k of the amplifier 13. Hereinafter, the correction operation will be described. In the figure, 24 is the amplifier 13
An adder for adding the output and the output of the microphone 14, 2
5 is an amplification factor correction circuit newly added in this embodiment,
26, 27 and 28 are differential amplifiers, 29 is a multiplier, 30 is an inverter for inverting the sign, and R ₁ R ₂ is a resistor. Output voltage kV amplification unit 13 enters the adder 24, the difference between the output voltage M of the time constant circuit 15 is taken. Voltage difference M
-KV passes through the switch 21 and is applied to the terminal of the capacitor 22. The correction operation for the terminal voltage of the capacitor 22 is the same as in the first embodiment.

The operation of correcting the amplification factor of the amplifier 13 is performed by the amplification factor correction circuit 25. The amplification factor correction circuit 25 includes a voltage V of the time constant circuit 12, a voltage M of the time constant circuit 15, and a voltage VMa corresponding to a predetermined maximum vehicle speed.
The amplification factor is set from four parameters of x and the voltage NMax corresponding to the noise at the maximum vehicle speed.

The maximum vehicle speed voltage VMax is obtained by the differential amplifier 26.
The difference between the maximum noise voltage NMax and the voltage M is calculated by the differential amplifier 27. Differential amplifier 2
8 and the multiplier constitute a division circuit, which can be realized by known means. The following equation is calculated by the division circuit to determine the amplification factor. _{k 2 = (NMax -M) /} (VMax -V) ··· (3) When the output of comparator 17 goes Low from High switch 21 is turned off condition, the amplification factor of the amplifier 13 is the k ₂ of the above formula The noise is held and the noise is estimated.

FIG. 6 shows the estimation operation. In the figure, the solid line is the estimated straight line of the expressway, and the broken line is the estimated straight line of the present embodiment. The dashed estimated straight line is a point D at which the vehicle speed becomes maximum, and a point B at which the comparator output is switched.
It is determined by two points.

[0042] In the second embodiment previously, it sets the upper limit value of the noise estimating the appropriate value. Therefore, there is an advantage that the estimated noise value can be prevented from excessively increasing even when noise detection by the microphone cannot be performed for a long time. For this reason, the volume does not increase excessively.

In the above embodiment, the amplification factor correction circuit constituted by using analog circuit elements is shown. However, the same effect can be obtained by employing a digital operation function such as a microcomputer or a digital signal processor. can get.

Embodiment 3 FIG. A third embodiment will be described with reference to FIG. FIG.
, The terminal voltage of the capacitor 22 remains at N ₀ ,
An example in which noise estimation is performed by changing only the amplification factor k of the amplifier 13 has been described. In the amplification factor correction circuit 25, the ratio k ₂ between the output voltage V of the time constant circuit 12 and the output voltage M of the time constant circuit 15
Is calculated. The ratio k ₂ is given by the following equation (4). _{k 2 = M / V ......... (} 4) When the output of the comparator 17 is switched to Low, the switch 21 is opened together switcher 41 is speed-side terminal 2
Switch to 3b. The amplification factor of the amplifier 13 is k at that time.
₂ and this and the capacitor that is the hold circuit
The estimation of the noise is performed based on the terminal voltage N ₀ of the terminal 22 . In this embodiment, the noise value at a vehicle speed of 0 km / h
Since the proportional coefficient between the vehicle speed and the noise value is changed without changing the terminal voltage of the hold circuit, there is an advantage that it can quickly follow a rapid change in the road surface condition in a short time.

In the above embodiment, the amplification factor correction circuit constituted by using an analog circuit element is shown. However, the same effect can be obtained by employing a digital operation function such as a microcomputer or a digital signal processor. Can be

[0046]

As described above, according to the present invention, since the noise estimated value based on the vehicle speed is corrected by the noise value of the microphone, the noise can be estimated with high accuracy even if the road environment or the vehicle type changes. This has the effect of automatically adjusting the volume and sound quality.

[Brief description of the drawings]

1 is a functional block diagram of a vehicle sound HibikiSo location according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of dynamic range compression and volume adjustment according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of low-frequency equalization according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating an operation of noise estimation according to an embodiment of the present invention.

5 is a functional block diagram of a vehicle sound HibikiSo <br/> location according to the second embodiment of the present invention.

FIG. 6 is an explanatory diagram illustrating an operation of noise estimation according to a second embodiment of the present invention.

7 is a functional block diagram of a vehicle sound HibikiSo <br/> location according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a difference in noise due to a conventional road surface roughness.

FIG. 9 is a block diagram showing a conventional sound reproducing device.

[Explanation of symbols]

1L, 1R input terminal 2 adder 3 main volume, 4 sound quality, volume adjustment circuit, 5L, 5R electronic volume, 6L, 6R low frequency equalizer circuit, 7L, 7R volume variable circuit, 8L, 8R power amplifier, 9L, 9R speaker , 10 vehicle speed sensor, 11 frequency-voltage conversion circuit, 12 time constant circuit,
13 amplifier, 14 microphone, 15, 16, 18 time constant circuit, 17 comparator, 19, 20, 24 adder,
21 switches, 22 a capacitor, 23a, 23b terminal, 2 6,27 differential amplifier, 25 amplification factor correction circuit, 28 an operational amplifier, 29 a multiplier, 30 inverter, 41 switching device.

Continuation of the front page (58) Fields investigated (Int. Cl. ⁶ , DB name) H03G 3/32 B60R 11/02 G10K 11/178 H04R 3/00 320 H04S 7/00

Claims (3)

(57) [Claims] The method according to claim 1] output of the audio apparatus mounted in a vehicle in that so as to adjust in accordance with the noise of the vehicle, a microphone for detecting the noise in the passenger compartment of the vehicle, a vehicle speed for detecting the speed of the vehicle A sensor for generating a noise output corresponding to the vehicle speed based on the output of the vehicle speed sensor ;
Sign inverted output of amplifier and output of above microphone
A first adder for adding the output of the amplifier and the output of the amplifier
The output of the hold circuit that holds the output potential of the adder
A second adder for adding a comparator for comparing the outputs of the acoustic device of the microphone, the con <br/> is on-off controlled by the output of the comparator, the output of the first adder when on Is provided to the hold circuit, and when the output level of the acoustic device is low ,
The output of the first adder and the output of the second adder
Amplification of the output of the sound device according to the added output
When the output level of the audio device is high , the output of the audio device is controlled according to the output of the second adder.
Vehicle acoustic apparatus according to claim and Turkey adjust the amplification factor of. 2. An apparatus for adjusting the output of an acoustic device mounted on a vehicle in accordance with the noise of the vehicle, wherein the microphone detects noise in the vehicle cabin of the vehicle, and a vehicle speed sensor detects the speed of the vehicle. An amplifier for generating a noise output corresponding to the vehicle speed based on the output of the vehicle speed sensor ;
Sign inverted output of amplifier and output of above microphone
A first adder for adding the output of the amplifier and the output of the amplifier
The output of the hold circuit that holds the output potential of the adder
Adder for adding the output of the microphone, and a comparator for comparing the output of the microphone with the output of the audio device. On / off control is performed by the output of the comparator. When the output is on, the output of the first adder is applied to the hold circuit. A first switch for performing the operation, a first differential amplifier for obtaining a difference between the output of the vehicle speed sensor and a first predetermined value, and a second differential amplifier for obtaining a difference between the output of the microphone and a second predetermined value. divider for obtaining a ratio of the output of said first and second differential amplifier, this
Divider及 beauty the comparator is synchronized with the first switch by the output on-off control of the output of the divider is supplied to the amplifier during on, becomes equal to the output of the divider the amplification factor of the amplifier a second switch that way, when the output level of the acoustic device is low, the upper
The output of the first adder and the output of the second adder are added.
Amplification factor for the output of the above acoustic device according to the calculated output
Adjust, when the output level of the acoustic device is high, the
The output of the audio device is adjusted according to the output of the second adder.
Vehicle acoustic apparatus according to claim and Turkey to adjust the amplification factor that. 3. An apparatus for adjusting the output of an acoustic device mounted on a vehicle in accordance with the noise of the vehicle, wherein the microphone detects noise in the cabin of the vehicle, and a vehicle speed sensor detects the speed of the vehicle. an amplifier produces a noise output corresponding to the vehicle speed based on the output of the vehicle speed sensor, this
Sign inverted output of amplifier and output of above microphone
A first adder for adding the output of the amplifier and the output of the amplifier
The output of the hold circuit that holds the output potential of the adder
Adder, a comparator for comparing the output of the microphone with the output of the audio device, a divider for obtaining a ratio between the output of the vehicle speed sensor and the output of the microphone, and on / off control by the output of the comparator When ON, the output of the divider is supplied to the amplifier,
Switch to turn the amplification factor of the amplifier becomes equal to the output of the divider, is switched controlled by the output of the switch and the comparator, selectively the outputs of the above microphone above Symbol second adder And a changeover switch which is taken out as an output control element of the audio device, and when the output level of the audio device is low, the output of the audio device is amplified according to the output of the microphone.
If the output level of the audio device is high , adjust the
Versus the output of the acoustic device in accordance with the output of the serial second adder
Vehicle acoustic apparatus according to claim and Turkey adjust the amplification factor of.