close

Вход

Забыли?

вход по аккаунту

?

JPH0879880

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH0879880
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker apparatus which corrects response characteristics of a transmission system including a
speaker by an inverse filter to prevent generation of distorted sound.
[0002]
2. Description of the Related Art In recent years, in multimedia, it has been required to improve
the quality of audio sound attached to an image. This is due to the fact that Hi-Fi audio, which is
not a mere sound, has become indispensable as the wide dynamic range of audio by CD-ROM has
become widespread. In this case, a small and high-performance speaker is required. For this
purpose, on the one hand, the faithful reproduction of a three-dimensional sound field including
a sound field and a sound image such as a sound field (surround) or a sound image (3D virtual
reality) for HiFi audio is pursued. In other words, the response characteristic of the transmission
system including the speaker is corrected by the inverse filter, and the audio reproduction in
which the distortion sound of the transmission system can not be heard is pursued, and various
attempts have been made in the latter. .
[0003]
Conventionally, for example, in Japanese Patent Application Laid-Open No. 3-143195, a linear
phase FIR type filter (FIR: Finite Impulse Response) is provided for each of a plurality of
frequency band channels, and a speaker unit corresponding to each of a plurality of frequency
08-05-2019
1
bands is provided. There has been disclosed a so-called multi-way speaker system in which
characteristics as a speaker system are improved and sound quality is improved by performing
digital signal processing suitable for the above.
[0004]
JP-A-57-79725 and JP-A-63-221708 disclose methods of simultaneously using an FIR type filter
and an IIR type filter (IIR: Infinite Impulse Response) as digital filters.
Among them, Japanese Patent Application Laid-Open No. 57-79725 discloses that a resonance
characteristic that changes in amplitude near a roll-off frequency outside the passband of the IIR
filter is removed by the FIR filter, Further, Japanese Patent Application Laid-Open No. 63221708 discloses that an FIR filter that variably adjusts the amplitude and an all-pass IIR filter
that variably adjusts the group delay amount are independently controlled.
[0005]
However, in the above-mentioned publication, if it is intended to correct the speaker
characteristics with only the FIR filter, the filter scale (filter coefficient length) must be made
extremely large, and vice versa However, reducing the filter size (if making it smaller) requires
performance to be sacrificed, and therefore be very large or poorly performing, which makes the
filter size (coefficient length) and group It has not been disclosed that the amount of delay is
made short and miniaturized and incorporated into the speaker enclosure.
[0006]
The present invention has been made to solve the problems associated with the conventional
example described above, and it is an object of the present invention to obtain a small and
inexpensive speaker device by shortening the filter size and the group delay amount. is there.
[0007]
SUMMARY OF THE INVENTION In order to achieve the above object, a speaker apparatus
according to the present invention comprises an inverse filter for correcting response
characteristics of a predetermined frequency band of the speaker in a bell in a specific frequency
band. Of a first filter composed of an IIR filter having desired characteristics such as a type and a
second filter composed of an FIR filter operating as a convolver in cascade connection, and the
characteristics of the first filter And an audio signal processing apparatus in which the filter
08-05-2019
2
coefficient length of the second filter is set to be optimized to a predetermined length.
[0008]
Further, the present invention is characterized in that the loudspeakers are provided with a
plurality of loudspeakers of a multi-way system, and the response characteristics of all the
loudspeakers are corrected by one inverse filter without division for each channel. It is
[0009]
Further, the present invention is characterized in that such an inverse filter is disposed in each
system of a three-dimensional sound field control unit consisting of a pair of convolvers.
[0010]
DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a system
configuration diagram showing a speaker apparatus according to a first embodiment.
In FIG. 1, two-channel stereo sound sources 1L and 1R generate desired audio signals.
The inverse filter 2L has cascaded first and second filters 3L and 4L for correcting speaker
output characteristics and realizing flat speaker reproduction of sound pressure characteristics
and phase characteristics, and the left (L ) Channel type.
The first filter 3L is configured of an IIR type filter having a bell-type characteristic that enhances
/ attenuates with respect to the 0 dB reference value by setting the center frequency and Q
(sharpness) in a specific frequency band.
On the other hand, the second filter 4L is configured by a convolver that is a convolution
operation processing circuit including an FIR type filter that corrects the remaining amplitude
and phase characteristics excluding the bell type characteristic of the first filter 3L.
Furthermore, the characteristics of the first filter 3L are set so as to optimize the filter coefficient
length of the second filter 4L to a predetermined length. Further, 2R is an inverse filter of a right
08-05-2019
3
(R) channel system provided with first and second filters 3R and 4R similar to the above left
channel system.
[0011]
Further, the output of the left channel convolver 4L is connected to a plurality of amplifiers 5L1
to 5L3 constituting a network provided for each channel of each frequency band of the left
channel system. In addition, these amplifiers 5L1 to 5L3 are connected to the speakers 6L1 to
6L3 in correspondence with each other. Similarly, 5R1 to 5R3 and 6R1 to 6R3 are a plurality of
amplifiers and speakers constituting a network provided for each channel of each frequency
band of the right channel system and a plurality of speakers for the left channel system and the
right channel system. The output characteristics of all the speakers are corrected by the single
inverse filters 2L and 2R of the left channel system and the right channel system described above
without being divided for each channel of each frequency band, and the sound pressure
characteristics are obtained. And flat speaker reproduction with phase characteristics.
[0012]
Further, the control unit 7 controls the characteristics of the inverse filters 2L and 2R, and a
coefficient memory 8 such as a ROM is connected to the control unit 7. The coefficient memory 8
stores in advance a coefficient relating to a characteristic complementary to the output
characteristic of the speaker when the convolution operation is performed by the second filter 4
(generally referred to 4L and 4R). The center frequency and Q of the bell-shaped characteristic
are set in the filter 3 (generally called 3L and 3R), and the coefficients are read out from the
memory 8 to perform convolution calculation processing on the time axis based on the
coefficients. The output characteristics of 6R1 to 6R3 are corrected with the inverse
characteristics to realize reproduction of a speaker having flat sound pressure characteristics and
phase characteristics.
[0013]
That is, as shown in FIG. 1, the speaker correction system (audio signal processing apparatus)
according to the present invention is a two-channel stereo speaker system and includes left and
right channel inverse filters 2L and 2R, a control unit 7, It comprises a memory 8. The speaker
correction system (audio signal processing device) for the left (L) channel system comprises the
08-05-2019
4
sound source 1L, the inverse filter 2L, the amplifiers 5L1 to 5L3 and the speakers 6L1 to 6L3,
and the speaker correction system for the right (R) channel system Is composed of a sound
source 1R, an inverse filter 2R, amplifiers 5R1-5R3, and speakers 6R1-6R3.
[0014]
In the above configuration, it is general to use an FIR filter as the inverse filter, but when the
inverse filters 2L and 2R are configured with only the FIR filter, for example, the present
inventors conducted experiments In the example (characteristic shown in FIG. 3 described later),
the number of taps (filter coefficient length) needs to be about 1200 or more (delay time = 1200
× (1/3200) × 1/2 = 0.1875 seconds) at a sampling frequency of 32 KHz It becomes. In addition
to this, when using the same size FIR type filter in the three-dimensional sound field control, an
additional 0.1875 seconds are required, which results in a 0.375 second delay. This is greater
than the allowable 0.33 seconds per frame.
[0015]
However, it is necessary to shorten the filter size (coefficient length) in order to reduce the time
lag (delay) with the image, and the merit that it can be incorporated in the speaker if it is
miniaturized is also possible. is there. Therefore, it is conceivable to significantly reduce the filter
size by using an IIR type filter with no time lag as an auxiliary, and in this way, it becomes
possible to enjoy HiFi audio sound even in multimedia. In this embodiment, as an inverse filter,
an FIR filter and an IIR filter are connected in cascade, and in this case, a bell type characteristic
is adopted as the IIR type filter, and the filter characteristic length of the FIR type filter is Set to
optimize to a predetermined length. In addition, since the bell type characteristic has a gentle
slope depending on Q (sharpness) without having a sharp roll-off like a band pass characteristic,
it is easy to set the slope adaptively.
[0016]
Next, a method of calculating the bell-shaped characteristic according to the above-mentioned IIR
type filter will be described. 2 shows the amplitude characteristics (A) of the transmission system
before correction when no inverse filter is provided in FIG. 1, and FIG. 3 shows the case where
only the second filter 4 is provided as the inverse filter 2 (generally called 2L and 2R). The
corrected amplitude characteristics (B) and (C) of the transmission system of FIG. 6 are shown
08-05-2019
5
respectively, and in FIG. 3, the amplitude characteristics (A) when realized with the inverse filter
of the number of taps (filter coefficient length) 1200 in FIG. The characteristic (C) shows the
characteristic when realized at 300. 4 shows the bell type characteristic, FIG. 5 shows the target
characteristic A of correction and the target characteristic B of new correction, and FIG. 6 shows
the amplitude when only the second filter 4 with the number of taps (filter coefficient length)
1200 is provided. The amplitude characteristic C corrected by the inverse filter 2 having the
second filter 4 of the number of taps (filter coefficient length) 300 shown in comparison with the
characteristic (B) and the first filter 3 of the bell type characteristic shown in FIG. Respectively.
[0017]
Now, as shown in FIG. 3, as the corrected amplitude characteristic of the transmission system
when only the second filter 4 is provided as the inverse filter 2, the amplitude characteristic in
the case of the number of taps (filter coefficient length) 1200 In the case where the number of
taps is small as in the amplitude characteristic (C) in the case of the number of taps (filter
coefficient length) 300 compared to (B), for example, in the case of a number of taps (filter
coefficient length) 1200 near 150 Hz. It can be seen that the error with the amplitude
characteristic (B) of FIG. 4 and the target characteristic A shown in FIG. That is, if the number of
taps (filter coefficient length) is reduced to reduce the filter size (if it is made smaller), the
performance will be sacrificed.
[0018]
Therefore, from the amplitude characteristic (C) in the case of the number of taps (filter
coefficient length) 300 shown in FIG. 3, a bell-shaped characteristic in which the center
frequency is 5 dB down at 150 Hz as shown in FIG. The first correction is performed by the first
filter 3 set as the IIR type filter of characteristics, and then the new correction target
characteristic B which is the characteristic excluding the bell characteristic from the correction
target characteristic A shown in FIG. When correction is performed using a second filter with
300 taps, an amplitude characteristic C shown in FIG. 6 is obtained. In particular, it can be seen
that the amplitude characteristic C has a reduced error with respect to the target characteristic as
compared with the amplitude characteristic (C) shown in FIG. That is, by setting the
characteristics of the first filter 3 so as to optimize the filter coefficient length of the second filter
4 to a predetermined length, the filter scale is reduced, and the multimedia HiFi audio is
embedded in the speaker. You can make it comfortable to enjoy.
08-05-2019
6
[0019]
Although not described in detail, as another method of calculating the characteristic of the bellshaped characteristic, for example, as shown in FIG. 2, the bell target BT may be directly obtained
from the amplitude characteristic (A). Also, here, depending on the amplitude characteristics, the
bell target BT may be not only one but also two or more. To identify such bell-shaped center
frequency and Q (sharpness), a bell analysis routine (by sweeping each parameter within a given
band) is run on the workstation to combine the IIR and FIR filters. The characteristic is
repeatedly determined until it finally falls within a predetermined deviation.
[0020]
Therefore, according to the first embodiment, the first filter in which the inverse filter 2 for
correcting the response characteristic of the predetermined frequency band of the speaker is
constituted by the IIR type filter having the bell type characteristic in the specific frequency band
3 and a second filter 4 configured by an FIR type filter operating as a convolver are connected in
cascade, and the characteristic of the first filter 3 is set such that the filter coefficient length of
the second filter 4 is a predetermined length When the audio signal processing apparatus is set
to be optimized to correct the response characteristics of the transmission system including the
speaker by the inverse filter 2 to perform audio reproduction such that distortion sound of the
transmission system can not be heard To reduce filter size, for example, to enjoy multimedia HiFi
audio comfortably in a speaker enclosure Kill.
[0021]
In addition, since a plurality of multi-way type speakers 6L1 to 6L3 and 6R1 to 6R3 are provided
as the speakers, and all the speakers are corrected by one reverse filter 2L and 2R without
division for each channel. The audio signal processing apparatus for correcting the speaker can
be incorporated in the speaker, the processing unit becomes inexpensive, and the speaker
apparatus can be miniaturized.
[0022]
Second Embodiment Next, FIG. 7 is a diagram for explaining a speaker apparatus according to a
second embodiment, wherein (a) is an external structural view and (b) is a circuit diagram of an
internal audio signal processing apparatus. is there.
08-05-2019
7
In this second embodiment, as shown in the appearance structure of FIG. 7A, a multi-way speaker
system is adopted as in the configuration of the first embodiment shown in FIG. Each of the
speakers 6L1 to 6L3 is not driven by an individual amplifier, but is driven by a single amplifier
5L, and the amplifier 5L and an inverse filter are integrated by the processing circuit unit 9 and
incorporated in a speaker device. It is like that.
Also, an infrared light receiving unit 10 for receiving a sound source and a remote control
(volume / on / off) command by infrared light from a main body 20 such as a player or a display
is provided. Reference numeral 11 denotes a conversion unit for converting infrared light
received by the infrared light receiving unit 10 into a reception signal, 12 denotes a distributor
for distributing the converted reception signal to the control unit 7 and the reverse filter 2L, and
13 denotes an amplifier 5L. The distributor which distributes a drive signal to each speaker 6L16L3 is shown. In addition, the same configuration as the left channel system is also provided in
the right channel system.
[0023]
Therefore, according to the second embodiment, the speakers of the multi-way speaker system
are driven not by the individual amplifiers but by the single amplifier 5L, so that the amplifiers
5L and the inverse filter are driven. And the like are integrated by the processing circuit unit 9
and incorporated in the speaker device, so that the processing circuit unit 9 can be configured at
low cost, and high performance and miniaturization of the speaker device can be achieved. In
addition, since the instruction is given by the infrared ray, the speaker device can be disposed
with good mobility to the optimum distance where stereo localization is easy, and is provided
separately from the main body such as the player and display. There is no leakage, and it can
have beautiful features such as not adversely affecting the computer etc. of the main unit. In
particular, it is most suitable for multimedia audio systems.
[0024]
Third Embodiment Next, FIG. 9 shows a block diagram of a speaker apparatus according to a
third embodiment combined with three-dimensional sound field control. The speaker apparatus
according to the third embodiment shown in FIG. 9 is provided with inverse filters 2L and 2R
according to the first embodiment in each system of a three-dimensional sound field control unit
including sound image localization filters 14L and 14R consisting of a pair of convolvers. By
adjusting the pair of sound image localization filters 14L and 14R by the control unit 7, the two
08-05-2019
8
speakers 6L and 6R can reproduce the virtual speaker 6I at an arbitrary position. Reference
numeral 15 denotes a CD-ROM, reference numerals 16a to 16c denote sound source data,
localization data and video data of the CD-ROM 15, and a display 17 displays video data.
[0025]
By this configuration, the total time delay is reduced, and even in combination with the threedimensional sound field control, the time delay can be suppressed to a time less than one frame
of the image, which hinders multimedia reproduction. I will not give it. Although not described in
detail here, NFB (negative feedback) technology is employed at low frequencies of, for example,
60 to 200 Hz in order to compensate for the bass which tends to be insufficient with small
speakers in the above embodiments. It goes without saying that the sound quality may be
improved.
[0026]
As described above, according to the present invention, the inverse filter for correcting the
response characteristic of the predetermined frequency band of the speaker is constituted by the
IIR type filter having the bell type characteristic in the specific frequency band. The first filter
and the second filter constituted by the FIR type filter operating as a convolver are connected in
cascade, and the characteristic of the first filter is set such that the filter coefficient length of the
second filter is a predetermined length Since the audio signal processing apparatus is set to be
optimized to the maximum resolution, the response characteristic of the transmission system
including the speaker is corrected by the inverse filter to perform audio reproduction such that
distortion sound of the transmission system can not be heard. Thus, a compact and inexpensive
speaker device can be obtained by shortening the filter size and the group delay amount.
[0027]
Also, audio signal processing is performed to correct the speakers by providing a plurality of
multi-way speakers as speakers and performing correction of all the speakers by one inverse
filter without dividing for each channel. The device can be made small and inexpensive, and can
be incorporated in a speaker, so that multimedia HiFi audio can be enjoyed comfortably.
[0028]
Furthermore, by providing an inverse filter in each system of the three-dimensional sound field
control unit consisting of a pair of convolvers, the time delay can be suppressed to less than one
frame of the image even in combination with the three-dimensional sound field control. It has the
08-05-2019
9
effect of being able to do so without affecting the multimedia playback.
[0029]
Brief description of the drawings
[0030]
1 is a general block diagram showing a first embodiment of the speaker apparatus of the present
invention.
[0031]
2 is a characteristic diagram showing an amplitude characteristic (A) before correction of the
transmission system when the inverse filter is not provided in FIG.
[0032]
FIG. 3 is a characteristic diagram respectively showing corrected amplitude characteristics (B)
and (C) of the transmission system when only the second filter 4 is provided as the inverse filter
2 (generally called 2L and 2R) in FIG. The amplitude characteristic (B) shows the characteristic
when realized by the inverse filter of the number of taps (filter coefficient length) 1200, and the
amplitude characteristic (C) shows the characteristic when realized by the same 300.
[0033]
4 is a characteristic diagram of the bell type characteristic.
[0034]
5 is a characteristic diagram showing the target characteristic A of the correction and the target
characteristic B of the new correction.
[0035]
The second filter 4 of the number of taps (filter coefficient length) 300 shown in comparison
with the amplitude characteristic (B) when only the second filter 4 of the number of taps (filter
coefficient length) 1200 is provided is shown in FIG. It is a characteristic view which shows
amplitude characteristic C corrected by inverse filter 2 which has the 1st filter 3 of the bell type
characteristic shown, respectively.
08-05-2019
10
[0036]
7 is an external view of a speaker apparatus according to a second embodiment of the present
invention and a block diagram of an internal processing circuit.
[0037]
8 is an external view of a speaker device according to a second embodiment of the present
invention and a block diagram of an internal processing circuit.
[0038]
<Figure 9> It is the whole block diagram which shows the 3rd example of the speaker device of
this invention.
[0039]
Explanation of sign
[0040]
1L, 1R Sound source 2L, 2R Inverse filter 3L, 3R First filter (IIR type filter) 4L, 4R Second filter
(FIR type filter, convolver) 5L1 to 5L3, 5R1 to 5R3 Amplifier 6L1 to 6L3, 6R1 to 6R3 Amplifier 7
Controller 8 Memory 14L, 14R Convolver (sound image localization filter)
08-05-2019
11
Документ
Категория
Без категории
Просмотров
0
Размер файла
23 Кб
Теги
jph0879880
1/--страниц
Пожаловаться на содержимое документа