JPS60183900A - Device for improving sound in automobile - Google Patents

Abstract

PURPOSE:To delete and to reduce stably sounds in an automobile by eliminating a sound generated from a speaker, and deleting only the original sound in the automobile, which is generated from the speaker to become noise among the sounds collected in the automobile. CONSTITUTION:A microphone 3 is provided close by a head rest 2 on the front seat 1 in an automobile. The output from the microphone 3 is amplified by an amplifier 4 for the microphone, and is inputted to an input terminal 6a in a differential amplifier 6 after passing through a filter 5 which filtrates only a sound signal in the required frequency range. The output of the amplifier 6 passes through a phase inversion circuit 7 and is inputted to a speaker amplifier 8. But the output of the circuit 7 is designed to be inputted to the other input terminal 6b in the amplifier 6 through a buffer amplifier 9. The sound signal amplified by the amplifier 8 is generated as a sound from a speaker 11 located behind the rear seat 10, thus the noise is invalidated and eliminated by an antiphase sound generated in the speaker 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a vehicle interior sound modification device that reduces vibration noise generated in a vehicle interior.

(Prior art) In the interior of a passenger car, etc., there are muffled sounds caused by changes in the volume of the passenger compartment and noise caused by vibrations of engine rotation, causing discomfort to passengers. -4 il.

Conventionally, countermeasures against noise within the wound have been taken by reducing the noise generation source such as the engine or the structural integrity of the I''i stopper structure. Attempts to achieve reductions pose problems such as increasing the number of vehicles, reducing comfort, and even significantly increasing vehicle prices.

*As an example of internal noise countermeasures, JP-A-57-136
In Publication No. 811, an automatic volume adjustment device is incorporated into a sound device such as a car stereo installed in a car, and the volume from the sound device is automatically adjusted according to the noise level inside the car while the car is running, so that music etc. It has been proposed to relatively reduce the influence of in-vehicle noise by making the sound louder than usual, but this noise countermeasure only relatively reduces the influence of rectangular noise. Yes, it is essentially a noise countermeasure.

The inventors of the present invention have conducted extensive research on how to essentially reduce the interior space of a vehicle without increasing the weight of the vehicle, reducing comfort, or significantly increasing the price of rabbit meat. The present inventor believes that the conventionally known method of superimposing a certain sound with a sound of the opposite phase to cancel out the sound is an effective method that can essentially reduce noise in the interior of a vehicle. As a result of further research, the following problems were discovered. In other words, the same sound that was collected inside the vehicle is simply reversed in phase.
It has been discovered that if the noise is emitted from the speaker into the vehicle interior, the interior of the vehicle is repeatedly erased and non-erased, making it impossible to sufficiently erase the interior of the vehicle.

(Object of the Invention) The object of the present invention is to invert the phase of the audio signal obtained by sound treatment in the passenger compartment, and to transmit the phase-inverted audio signal to a system installed in the passenger compartment. Repeated cancellation and non-cancellation of the same sound in the passenger compartment that occurs when a sound with a phase opposite to the sound picked up in the sub-compartment is generated by giving it to a speaker to eliminate or reduce the sound in the passenger compartment. It is an object of the present invention to provide a vehicle interior sound number η device which eliminates noise and can stably remove or reduce tp in a vehicle interior.

(Structure of the Invention) The silkworm room sound modification module' of the present invention includes a microphone that is installed in the car interior and collects the car interior sound and converts it into an audio signal;
A filter for extracting an audio signal in a predetermined frequency range from the audio signal, a phase inverting unit for inverting the phase of the audio signal that has passed through the filtering unit, and audio inverted by the phase inverting unit. A speaker for emitting a signal into the vehicle interior, and a subtraction circuit provided between the filter means and the phase inversion means to subtract the audio signal generated from the speaker from the audio signal input to the phase inversion means. It is characterized by: l? D. In the present invention, the sound emitted by the speaker is removed from the collected sound inside the car, and only the original sound inside the car that is generated by the speaker and generated by the sound signal is erased. Therefore, it is possible to stably eliminate or reduce the depletion of the interior of the vehicle without repeating erasing and non-erasing of the vehicle interior as in the conventional case.

(Example) Hereinafter, an example of the sieve of the correct room sound improvement device of the present invention will be described in detail with reference to the drawings.

A microphone 3 is installed near the left side 2 of the music seat L in the car, and the output from this microphone 3 is amplified by a microphone amplifier 4, and then only audio signals in a predetermined frequency range are emitted. The signal passes through the wave filter 5 and is input to one input terminal 6a of the differential amplifier 6. The output of the differential amplifier 6 is input to the speaker amplifier 8 after passing through the phase inversion circuit 7, but the output of the phase inversion circuit 7 is also input to the other input terminal 6b of the differential amplifier 6 via the buffer amplifier 9. It's asking me to type.

An audio signal amplified by a speaker amplifier 8 is installed behind the rear seat 10.
1 as sound, and the noise is canceled by the opposite-phase sound generated from the speaker 11 and eliminated.

The noise removal in the cabin homosonic reformer constructed in this manner will be explained in further detail.

When the device of this embodiment is activated, the microphone 3 absorbs the vehicle interior noise PN (j+) (see FIG. 2A) and converts it into an audio signal, and this audio signal PN (t 1 ) is amplified by the amplifier 4. After that, only the audio signal PIi O+) in a predetermined frequency range is passed through the filter 5 (see Figure 2B). In the differential amplifier f6, a voltage is likely to be applied to the terminal 6b on the decreasing a side when the circuit is started, so the audio signal pN(tl) that has passed through the filter 5 passes through the differential amplifier as it is and is sent to the phase inversion circuit 7. The phase is inverted at This phase-inverted vehicle interior noise PIN (tl
) is the audio signal ρs from the speaker 11 via the amplifier 8.
(t2) (see Figure 2b) and is added to the cabin noise ρN Ct2) to achieve the removal of jl-MV (see Figure 2b). The time when the vehicle interior noise PN(t+) is picked up by the microphone 3, and the time when the opposite phase signal "N(t+)" of this audio signal PN(t+) is emitted from the speaker 11 as the audio signal Ps(t2). Although it cannot be the same due to the influence of circuit delay, this delay can be virtually ignored in the case of relatively low-frequency noise such as muffled sounds.Microphone: 11 Next, the vehicle interior 1
The axial sound PN (t2) and the speaker reproduction sound Ps' (t2) at the position of the microbore 23 are absorbed and passed through the filter 5 in the same manner as described above. In the differential amplifier 6, the audio signal PN (t2)+Ps' (
t2) The audio signal ρ5 generated from the speaker 11
(t2) is subtracted. Assuming that the noise to be removed, that is, the highest frequency of the filter 5, is, for example, 1008Z or less, the distance from the speaker 11 to the microphone 3 is less than half a wavelength, so the speaker reproduction sound Ps'(ts) at the microbo 23 position and the speaker Since it can be considered that it is almost equal to the speaker reproduced sound Ps(t2) in 11th place 11a, it becomes the output cover PN(t2) of the differential amplifier.

This audio signal PN(t2) is emitted from the phased speaker 11 in the phase inversion circuit 7, and is combined with the next vehicle interior noise PN(ts) to remove 1≠sound. Thereafter, in the same manner, the noise inside the vehicle is stably suppressed successively after +ll.

Next, in order to make the effect of the present invention more clear, we will use the results of dog soap.
Present invention'f: Explain.

As an experimental vehicle, we used a 69-inch (manufactured by Toyo Jogyo Co., Ltd.) vehicle with a diameter of 69 mm, and installed a microphone that picks up sound from the interior of the vehicle in the headrest between the front seats.
As a circuit for suppressing the Oki indoor sound modification system, a speaker with cm impedance of 8 Ω is installed in the right rear window V.
Those described in Figures 1 and 83 were used. 46
The figure shows the circuit shown by the block in FIG.
, phase inversion circuit 7, buffer completion f91f; - all oP
End of the story! has been done. The filter is a five-piece bandpass filter, and is designed to remove only the audio signal No. 1 in the desired i and A3 wave number bands. In Kimi/Sample, 5 to 1 of the issues are recorded in the voice 1 picked up by the microphone.
The circuit constants of the resistor and the resistor of the filter 5 were determined so as to pass only the audio (signal) of 00H2.

In addition, +J]' is applied to the input terminals 6a and 6b of the differential amplifier f6.
A variable resistance is provided so that the subtraction ratio is adjusted to A. The muffled noise before the engine idle was measured when the in-vehicle reformer t'jk constructed and arranged as described above was used and when it was not used.

'It 4 Figures 4A and 4B show 6fll fixed failure. FIG. 4A and FIG. 4B show the sound pressure level of the muffled field regarding the engine primary sound and the engine secondary sound, respectively, with respect to the tracking bone frequency and the engine rotation speed, and the solid line in the diagram shows the sound pressure level of the muffled field regarding the engine primary sound and the engine secondary sound, respectively, and the solid line in the diagram shows Vehicle interior maki reformer j6
The dotted line indicates the sound pressure level when the in-vehicle reformer 4 of the present invention is not used.

As can be seen from FIGS. 4A and 44B, when the device of the present invention is used for one period, the muffled idle noise of the engine's primary fluid and secondary sound will be reduced to at least 8 to 53 Hz (at an engine speed of 500 to 1600 rpm). ), the peak level was reduced to 103d8r, (92dB or less) due to the significant recasting 14j.

It should be noted that the in-vehicle reformer of the present invention has 6 grooved circuit parts to achieve high-speed operation, and by changing the P-wave frequency range of the filter, it is possible to eliminate high-frequency noise such as ) It becomes possible to leave out 1 even for ``kiri-tk'' and the like. It goes without saying that a low-pass filter can be used as a filter in addition to a band-pass filter.

(Effects of the Invention) In the present invention, by adding 2 muffled sounds, etc., and a bell sound, the sound inside the vehicle interior and the phase sound, the interior of the vehicle interior can be eliminated in a woody manner. It is possible to stably erase or reduce the interior of the vehicle without the repetition of erasure and non-erasure of the interior of the vehicle that occurs when trying to lower θ・k, and it is specially designed for vehicles with 14 construction. There is no need to make any major modifications, and an extremely effective measure against discomfort can be taken at a low cost.

Figure 1'/ij of Figure 49 is a schematic diagram showing an embodiment of the sound reforming system in the vehicle roof according to the present invention;
Figure 6 is a circuit diagram substantively showing the circuit indicated by the block in Figure 1. Figure 4A and Figure 4B No. 1 Measurement results obtained by the present invention This is a graph showing.

Claims (1)

[Claims] A microphone installed in the vehicle interior picks up the sounds inside the vehicle and converts them into audio signals; a filter means extracts an audio signal in a predetermined frequency range from the audio signal; and a filter means inverts the audio signal that has passed through the filter means. a speaker for emitting an audio signal inverted by the phase inversion means into the vehicle interior; and a speaker provided between the filter means and the phase inversion means 4+ to input the audio signal to the phase inversion means. A subtraction circuit for subtracting the audio signal generated from the speaker from the signal.