JP2003076374A - Audio device and adjusting method of the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an audio device whose filter can be adjusted easily and at high accuracy in a state in which a speaker is mounted at the prescribed position of the device and the adjusting method of the audio device. SOLUTION: In this audio device, sinusoidal signals of 20 Hz to 200 Hz are successively outputted from an oscillator 11 and the sounds outputted from a speaker 18 are collected by a microphone 19. A microcomputer 17 detects the reproduction limiting frequency of the speaker 18 by detecting levels of the signals outputted from the microphone 19. Then, the computer 17 sets the cutoff frequency of the high-pass filter (HPF) in a DSP (digital signal processor) 15 as the reproduction limiting frequency of the speaker 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio device and an audio device adjusting method for adjusting a filter with a speaker attached, and more particularly, to a speaker reproduction limit frequency (lower limit value of a reproducible frequency band) or less. The present invention relates to an audio device having a function of cutting a frequency signal and a method of adjusting the audio device.

[0002]

2. Description of the Related Art In recent years, there has been a demand for higher performance and more multifunctional in-vehicle audio devices. Along with this, a multi-speaker system (two-way and three-way speaker system) in which a plurality of speakers having different reproduction bands are combined, and a speaker system having a subwoofer dedicated to heavy bass reproduction have come to be used.

In order to maximize the performance of such a speaker system, a high pass filter, a band pass filter, a parametric equalizer or the like (hereinafter, simply referred to as "filter") has been used.

These filters have a large circuit scale, and it has hitherto been considered difficult to incorporate them in a head unit (HU) of a vehicle audio device. However, with the spread of digital signal processors (hereinafter referred to as "DSPs"), it becomes possible to configure these filters in the DSP and set the filter coefficients by software, and these are also applied to the head unit of the vehicle audio device. Now comes with a built-in filter.

[0005]

Each speaker has its own reproducible frequency band. When a signal with a frequency lower than the lower limit value of this reproducible frequency band (hereinafter referred to as "reproduction limit frequency") is supplied, a sound with large distortion (so-called muffled sound) is generated and the musicality is significantly impaired. Be done. Therefore, as described above, the high-pass filter, the band-pass filter, or the parametric equalizer is used to prevent the speaker from being supplied with a signal having a frequency lower than the reproduction limit frequency.

However, even if the same speaker is used, the reproduction limit frequency of the speaker changes depending on the vehicle structure and mounting position. Generally, when a speaker is attached to a vehicle, the reproduction limit frequency becomes high. For this reason,
It is preferable to measure the reproduction limit frequency of the speaker with the speaker attached to the vehicle and adjust the cutoff frequency of the filter.

However, adjustment of a filter of a conventional audio device requires a dedicated measuring instrument and experience, and cannot be easily performed by a user.

In view of the above, it is an object of the present invention to provide an audio apparatus and an audio apparatus adjusting method which can easily and accurately adjust a filter with a speaker attached at a predetermined position.

[0009]

An audio device of the present invention comprises an oscillator for generating a reference signal, a speaker to which the reference signal is supplied, and a cutoff frequency connected between the oscillator and the speaker. An adjustable filter, a microphone that collects the sound output from the speaker, and the frequency of the reference signal output from the oscillator are changed, and the level of the signal output from the microphone is detected. And a control unit that adjusts the cutoff frequency of the filter according to the detection result.

In the present invention, the filter means a circuit having a function of selectively attenuating a signal lower than a specific frequency. Filters include parametric equalizers as well as high pass and band pass filters.

In the present invention, the reference signal generated by the oscillator is supplied to the speaker, the sound output from the speaker is picked up by the microphone, and the level of the signal output from the microphone is checked.

When the frequency of the reference signal is higher than the reproduction limit frequency of the speaker, the speaker can efficiently convert the electric signal into sound, so that the level of the output signal from the microphone becomes high. On the other hand, when the frequency of the reference signal is lower than the reproduction limit frequency of the speaker, the conversion efficiency of the speaker is significantly reduced, and the level of the output signal from the microphone is low. Therefore, the reproduction limit frequency of the speaker can be detected by checking the level of the output signal from the microphone while changing the frequency of the reference signal. The control unit automatically adjusts the cutoff frequency of the filter so as to cut a frequency lower than the reproduction limit frequency. This allows you to enjoy music with less distortion.

Instead of automatically adjusting the cutoff frequency of the filter by the control unit, the detection result of the reproduction limit frequency of the speaker is displayed on the display, and the user manually adjusts the cutoff frequency of the filter while looking at this display. You may allow it.

In the method for adjusting an audio device according to the present invention, while changing the frequency of the reference signal supplied to the speaker, the sound output from the speaker is picked up by the microphone and the level of the signal output from the microphone is adjusted. Based on the result, the reproduction limit frequency of the speaker is checked, and the filter connected to the front stage of the speaker is adjusted according to the result. As a result, it is possible to cut frequencies below the reproduction limit frequency of the speaker that causes distortion,
You can enjoy music with little distortion.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a block diagram showing the configuration of the audio device of the embodiment of FIG. The present embodiment shows an example in which the present invention is applied to a head unit of an in-vehicle audio device.

This audio device comprises an oscillator 11, a signal switch 12, an electronic volume 13, and an amplifier 14.
, A digital signal processor (hereinafter referred to as DSP) 15, an amplifier 16, and a microcomputer 17
It is composed of and. The output of the amplifier 14 is supplied to the speaker 18, and the signal output from the microphone 19 is supplied to the input end of the amplifier 16.

The oscillator 11 is a microcomputer 17
To generate a sinusoidal signal with a frequency between 20 Hz and 200 Hz. The sine wave signal output from the oscillator 11 has a constant amplitude even if the frequency changes. Although a sine wave signal is used as the reference signal in this embodiment, the reference signal is not limited to the sine wave signal in the present invention.

The signal switcher 12 outputs the output of the oscillator 11 and the audio signal output from an audio signal output device (not shown) such as a CD player or an FM / AM tuner according to the signal from the microcomputer 17. Either one of them is transmitted to the electronic volume 13.

The electronic volume 13 transfers the signal input from the signal switch 12 to the DSP 15, adjusts the signal input from the DSP 15 to a level according to the signal from the microcomputer 17, and outputs the signal.

The DSP 15 constitutes an audio equalizer (EQ) and a high pass filter (HPF) according to a predetermined program. The adjustment of the level of each frequency band of the audio equalizer and the adjustment of the cutoff frequency of the high pass filter are performed according to the signal from the microcomputer 17.

The amplifier 14 amplifies the signal input from the electronic volume 13 and supplies it to the speaker 18. The microphone 19 is installed at a listening point in the vehicle compartment and picks up the sound output from the speaker 18 and converts it into an electric signal. The amplifier 16 amplifies the signal output from the microphone 19 and transmits it to the microcomputer 17.

The microcomputer 17 operates based on a preset program and controls the oscillator 11, the signal switch 12 and the DSP 15. Further, the microcomputer 17 has a built-in A / D (analog / digital) converter, converts the signal transmitted from the amplifier 16 into a digital signal, processes the signal in accordance with a preset program, and outputs the signal to the microphone 19. The level of the signal output from is detected.

The operation of the audio apparatus (head unit) of the present embodiment having the above-mentioned configuration will be described below with reference to the flowchart shown in FIG.

First, after mounting the speaker 18 on the vehicle and setting the audio device to the speaker automatic correction mode, the microcomputer 17 causes the signal switch 1 to operate.
2 is controlled so that the output of the oscillator 11 is supplied to the electronic volume 13. Then, in step S11, the microcomputer 17 sets the frequency of the oscillator 11 to the initial value (20 Hz).

Next, in step S12, the oscillator 1
1 generates a sine wave signal having a frequency set by the microcomputer 17. This sine wave signal is sent to the signal switch 12, the electronic volume 13, the DSP 15, and the amplifier 1.
4 is supplied to the speaker 18. At this time, the level of each frequency band is not adjusted by the equalizer (EQ) in the DSP 15 (flat characteristic), and the cutoff frequency of the high-pass filter is the lower limit value (2).
0 Hz or less).

Thereafter, in step S13, the sound output from the speaker 18 is picked up by the microphone 19 and converted into an electric signal. Then, the process shifts to step S14, and the microcomputer 17 detects the level of the signal output from the microphone 19.

In step S15, it is determined whether or not the frequency of the signal output from the oscillator 11 is the upper limit value (200 Hz). If it is not the upper limit, the process proceeds to step S16, the frequency of the oscillator 11 is increased (for example, +10 Hz), and then the process returns to step S12. Then, the processing from step S12 to step S14 is repeated to supply the sine wave signal of the new frequency to the speaker 18, and the microphone 19
The level of the signal output from is detected.

In this way, 20 Hz to 200 Hz
The sine wave signals up to are sequentially supplied to the speaker 18, and when the level of the signal of each frequency output from the microphone 19 is detected, the process proceeds from step S15 to step S17.

In step S17, the microcomputer 17 analyzes the frequency characteristic of the speaker 18 based on the detection result of the level for each frequency. For example, when the frequency is plotted on the horizontal axis and the level is plotted on the vertical axis and the level value for each frequency is plotted, the frequency characteristic as shown in FIG. 3 is shown. A low level at a low frequency and a high level at a high frequency indicate that a signal lower than the reproduction limit frequency of the speaker 18 is inefficient when converted into sound, and a signal higher than the reproduction limit frequency is converted into sound. This is because the efficiency is high.

Based on such frequency characteristics, the microcomputer 17 detects the reproduction limit frequency of the speaker 18 in step S18 and sets the reproduction limit frequency as the cutoff frequency of the high pass filter (HPF). For example, the microcomputer 17 determines the cut-off frequency of the filter by setting the frequency at which the frequency is 200 Hz or a level near the level of which is 15 dB lower than that of the flat portion as the reproduction limit frequency of the speaker 18. The reproduction limit frequency of the speaker 18 may be a frequency that is 15 dB higher than the signal level of the frequency of 20 Hz or its vicinity.

After that, the process shifts to step S19, and the microcomputer 17 changes the coefficient of the high-pass filter in the DSP 15 to set the cutoff frequency determined in step S18. This completes the setting of the cutoff frequency of the high pass filter.

When the setting of the cutoff frequency of the high-pass filter is completed in this way, the microcomputer 17 stops the oscillator 11 and the signal switch 12
Is controlled so that an audio signal output from an audio signal output device such as a CD player or an AM / FM tuner is transmitted to the electronic volume 13.

According to the present embodiment, the reproduction limit frequency of the speaker and the speaker different in the mounting position are automatically measured, and the cutoff frequency of the high-pass filter is set according to the measurement result. This allows the speaker 1
In FIG. 8, a signal below the reproduction limit frequency that causes distortion is not supplied, and an effect that music can be enjoyed with clear sound quality can be obtained.

Further, according to the present embodiment, the reproduction limit frequency of the speaker is measured with the speaker attached, and the cutoff frequency of the high pass filter is automatically set according to the measurement result. Even an inexperienced user can enjoy high quality music.

In the above embodiment, the case where the signal below the reproduction limit frequency is cut by the high pass filter has been described, but the signal below the reproduction limit frequency may be cut by the graphic equalizer or the parametric equalizer.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
FIG. 3 is a block diagram showing the configuration of the audio device of the embodiment of FIG. This embodiment also shows an example in which the present invention is applied to a head unit of a vehicle-mounted audio device. 4, the same components as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

In addition to the configuration shown in FIG. 1, the audio device (head unit) of this embodiment has a display 20 capable of displaying arbitrary characters and figures and a cutoff frequency of a high-pass filter in the DSP 15 which is manually set. An operation unit 21 having an operation button for making adjustment possible is provided.

The head unit of the car audio system has a display 20 capable of displaying arbitrary characters and figures.
Many are equipped with. On the display 20, for example, a radio station name and a reception frequency are displayed when the radio is being received, and a music title, an artist name, a track number, a playing time and the like are displayed during CD reproduction.

On such a display 20, the frequency characteristic analyzed by the microcomputer 17 can be displayed. That is, in the present embodiment, the frequency characteristic of the speaker and the cutoff frequency of the high pass filter are displayed on the display 20 as shown in FIG. 5, and the user operates the operation unit 21 while watching the display 20,
Manually set the cutoff frequency of the high pass filter.

In the present embodiment as well, as in the first embodiment, even a user who does not have knowledge of audio can easily adjust the cutoff frequency of the high-pass filter, and clear it. The effect that you can enjoy music with various sound quality is obtained.

When a signal equal to or lower than the reproduction limit frequency of the speaker is cut by the graphic equalizer or the parametric equalizer, for example, the frequency of the reference signal output from the oscillator 11 is matched with the settable frequency of the graphic equalizer or the parametric equalizer. Thus, it becomes easier to set the cutoff frequency. For example, the selectable frequency of the graphic equalizer or the parametric equalizer is 20 Hz, 31.5.
Hz, 43Hz, 63Hz, 80Hz, 125Hz, ...
Then, the frequency of the sine wave signal output from the oscillator 11 is also set to be the same as these frequencies.

Further, in this embodiment, the display 20
Although the frequency characteristic of the speaker 18 is graphically displayed as shown in FIG. 5, the signal level for each frequency may be displayed numerically.

(Third Embodiment) FIG. 6 shows a third embodiment in which the present invention is applied to a 2-way vehicle-mounted speaker system. Since the basic configuration of the audio device (head unit) of this embodiment is the same as that of the first embodiment, it will be described with reference to FIG.

In the vehicle compartment, speakers FR, FL, RR, RL are arranged on the left and right sides of the front and rear sides, respectively, and a subwoofer SW is arranged in the center of the rear. Here, front and rear speakers FR, F
It is assumed that the reproduction frequencies of L, RR, and RL are the same.

In such a 2-way speaker system, as shown in FIG. 6, in the deep bass range (for example, 200 Hz).
The following) is reproduced by the subwoofer SW, and sounds of higher frequencies are reproduced by the front speakers FR, FL and the rear speakers RR, RL. By cutting the signals below the reproduction limit frequency of the front speakers FR and FL and the rear speakers RR and RL with the high-pass filter, it is possible to enjoy music with clear sound quality.

That is, in the present embodiment, 2 output from the oscillator 11 to the speakers FR, FL, RR, RL.
A sine wave signal from 0 Hz to 200 Hz is sequentially supplied, the level of the signal output from the speaker 18 is examined, and the cutoff frequency of the high pass filter is determined.

In this case, a high-pass filter for each speaker is individually provided in the DSP 15, and the reproduction limit frequencies of the front speakers FR and FL and the rear speakers RR and RL are individually measured to obtain the high-pass filter for each speaker. It is preferable to individually set the cutoff frequency of.

According to the present embodiment, the reproduction limit frequencies of the speakers FR, FL, RR, RL of the two-way speaker system are measured, and the signals of the frequencies equal to or lower than the reproduction limit frequency are output to these speakers FR, FL, RR ,. Since the cut-off frequency of the high-pass filter is adjusted so that it is not supplied to the RL, from the deep bass reproduced by the subwoofer SW to the front speakers FR, FL and the rear speaker R.
There is little distortion of the frequency band up to the bass played by R and RL, and you can enjoy music with clear sound quality.

(Fourth Embodiment) A fourth embodiment in which the present invention is applied to a 3-way speaker system will be described below with reference to the diagram shown in FIG. Also in this embodiment, the basic structure of the head unit is the same as that of the first embodiment, and therefore, the description will be given with reference to FIG.

The three-way system is composed of three speakers, a tweeter TW for high tone reproduction, a midrange speaker MD for medium tone reproduction and a woofer WF for low tone reproduction.

In such a three-way speaker system, as shown in FIG. 9, the low range is reproduced by the woofer WF, the middle range is reproduced by the midrange speaker MD, and the high range is reproduced by the tweeter TW.
Here, it is assumed that a signal processing circuit for 6 channels is configured in the DSP 15 and a signal is individually supplied from each signal processing circuit to each speaker. By cutting the signal below the reproduction limit frequency of the midrange speaker MD with the high-pass filter, it is possible to listen to music with clear sound quality.

That is, the sine wave signal output from the oscillator 11 is supplied to the midrange speaker MD, the level of each signal output from the microphone 19 is checked by the microcomputer 17, and the cutoff frequency of the high pass filter is determined. decide. Then, the cutoff frequency of the high-pass filter for the midrange speaker in the DSP 15 is set to the frequency determined by the microcomputer 17.

Also in this embodiment, the reproduction limit frequency of the midrange speaker MD is measured, and the cutoff frequency of the high-pass filter for the midrange speaker is set according to the measurement result, so that clear sound quality without distortion is obtained. You can enjoy music.

[0055]

As described above, according to the audio device and the adjusting method of the audio device of the present invention, the frequency of the reference signal supplied to the speaker is changed to detect the level of the signal output from the microphone. The cutoff frequency of the filter is set automatically or manually based on the result, so it is possible to detect the reproduction limit frequency of the speaker with the speaker installed, and the reproduction limit frequency below the reproduction limit frequency that causes distortion. It is possible to prevent a frequency signal from being supplied to the speaker, and even a user who does not have knowledge of audio can enjoy music with clear sound quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an audio device (head unit) according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of the audio device according to the first embodiment.

FIG. 3 is a diagram showing an example of frequency characteristics of a speaker.

FIG. 4 is a block diagram showing a configuration of an audio device (head unit) according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a display example of a display in the audio device according to the second embodiment.

FIG. 6 is a view showing a third embodiment in which the present invention is applied to a 2-way vehicle-mounted speaker system.

FIG. 7 is a diagram showing frequency characteristics of a front (rear) speaker and a subwoofer in a 2-way speaker system.

FIG. 8 is a diagram showing a fourth embodiment in which the present invention is applied to a 3-way speaker system.

FIG. 9 is a diagram showing frequency characteristics of a woofer and a tweeter in a 3-way speaker system.

[Explanation of symbols]

11 ... oscillator, 12 ... signal switch, 13 ... electronic volume, 14, 16 ... Amp, 15. Digital signal processor (DSP), 17 ... Microcomputer, 18 ... speaker, 19 ... Mike, 20 ... Display, 21 ... Operation part.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masakazu Akiu             1-8 Nishigotanda, Shinagawa-ku, Tokyo             Within Lupine Co., Ltd. F-term (reference) 5D062 BB20

Claims (5)

[Claims] 1. An oscillator for generating a reference signal, a speaker to which the reference signal is supplied, a filter having an adjustable cutoff frequency connected between the oscillator and the speaker, and output from the speaker. A microphone for picking up a sound, and the frequency of the reference signal output from the oscillator is changed, and the level of the signal output from the microphone is detected, and the cutoff frequency of the filter is detected according to the detection result. An audio device, comprising: 2. The audio device according to claim 1, wherein the filter comprises a digital signal processor. 3. An oscillator for generating a reference signal, a speaker to which the reference signal is supplied, a filter having an adjustable cutoff frequency connected between the oscillator and the speaker, and output from the speaker. And a control unit for changing the frequency of the reference signal output from the oscillator, detecting the level of the signal output from the microphone, and displaying the result on a display. An audio device characterized by the above. 4. The audio device according to claim 3, wherein the filter is constituted by a digital signal processor. 5. The reproduction limit frequency of the speaker is collected based on the level of the signal output from the microphone while collecting the sound output from the speaker while changing the frequency of the reference signal supplied to the speaker. And adjusting the filter connected to the front stage of the speaker according to the result of the check.