JP2572057Y2 - Digital channel divider for speakers - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital channel divider used in a multi-amplifier type speaker system.

[0002]

2. Description of the Related Art In a multi-way speaker system using a speaker dedicated to a frequency band, an LC network system using a coil and a capacitor, or a multi-amplifier system using a dedicated channel divider for each frequency band (channel) is used. Has been adopted.

FIG. 5 shows a multi-amplifier type speaker system using a digital channel divider disclosed in Japanese Utility Model Publication No. 2-6673. Reference numeral 2 denotes a power amplifier, and a plurality of power amplifiers assigned to each frequency band. amplifier 2 _{1, 2} 2, includes a ...... 2 _n. Reference numeral 3 denotes a speaker unit having a plurality of speaker units 3 ₁ , 3 ₂ ,..., 3 _n assigned to each frequency band. Numeral 4 denotes a digital channel divider (frequency band dividing circuit), which includes a plurality of linear phase FIR filters 4 ₁ , 4 ₂ ,..., 4 _n assigned to each frequency band and linear phase FIR filters 4 ₁ to 4. a plurality of filter coefficients assigned to _n variable device 4 _11, 4 _22, and a ...... 4 _nn. Each of the filter coefficient variable devices 4 ₁₁ to 4 _nn is a linear phase FIR type filter 4.
_This is arithmetic means for giving filter coefficients for giving desired frequency band division characteristics to ₁ to 4 _n . Reference numeral 5 denotes a D / A conversion circuit, which includes a plurality of D / A assigned to each frequency band.
Converter 5 _1, 5 _2, having ...... 5 _n.

According to the speaker system of the multi-amplifier system, first, each linear phase FIR type filter 4 ₁ .
4 _n is the desired frequency band division characteristic convolution operation using a filter coefficient obtained by performing from the filter coefficient changing device 4 ₁₁ to 4 _nn, frequency divides the input digital signal. Then, the D / A converter 5 ₁ to 5 _n converts the output from the linear phase FIR type filter 4 ₁ to 4 _n into an analog signal. Furthermore, the power amplifier 2 ₁ to 2 _n is the D / A
The output from the transducer 5 ₁ to 5 _n is amplified to a predetermined level, and a speaker unit 3 ₁ to 3 _n are converted into sound.

[0005]

In such a multi-amplifier type speaker system, linear phase FIR filters 4 ₁ to 4 _n are used for the digital channel divider 4. Can hold. However, speaker unit 3
Is generally not in a linear phase, the sound pressure frequency characteristic finally obtained by the speaker unit 3 cannot always be in a linear phase. As a result, the waveform of the reproduced sound is distorted, and it is difficult to reproduce the sound faithfully.

The present invention has been made to solve the above-described problems, and realizes sound pressure flatness and phase linearization at a frequency higher than the lowest resonance frequency of a speaker unit, and faithfully transmits and reproduces an acoustic signal. It is intended to provide a digital channel divider for a speaker that can be realized.

[0007]

A digital channel divider for a speaker according to the present invention includes a digital frequency band dividing circuit for dividing an input signal into signals for each frequency band, and a sound pressure frequency characteristic of the speaker unit. a characteristic correction inverse filter to provide an inverse characteristic, the cutoff that substantially matches the minimum resonance frequency of the speaker <br/> over unit
It is characterized in this <br/> and that includes a digital high pass filter with a frequency.

[0008]

According to the digital channel divider of the present invention, the characteristic correction inverse filter realizes the flattening of the amplitude characteristic of the digital signal frequency-divided into the frequency band and the linearization of the phase frequency characteristic. In general, since the sound pressure frequency characteristic of the speaker unit decreases in the low frequency range, the sound pressure level in the low frequency range necessarily increases as the frequency characteristic of the characteristic correction inverse filter. It will be the shape that was made. Therefore, a digital high-pass filter whose cut-off frequency is made almost equal to the lowest resonance number of the speaker unit efficiently suppresses excessive input to the speaker unit in a low frequency range. This allows
Above the lowest resonance frequency of the speaker unit, a sound pressure flatness and a phase straight line are realized, and faithful transmission and reproduction of an acoustic signal can be realized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below by assigning the same reference numerals to the same parts as those of the above-mentioned conventional structure. FIG. 1 is a block diagram of a first embodiment. Reference numeral 2 _denotes a power amplifier composed of a plurality of power amplifiers 2 ₁ , 2 ₂ ,..., 2 _n assigned to respective frequency bands, and 3 designates a power amplifier assigned to each frequency band. a plurality of speaker units 3 _1, 3 _2, the speaker unit consisting ...... 3 _n, 5 comprises a plurality of D / a converter 5 _1, 5 _2, ...... 5 _n assigned to each frequency band D / A
3 shows a conversion circuit.

Reference numeral 10 denotes a digital channel divider,
It has a frequency band dividing circuit 4, a digital high-pass filter 6, and an inverse filter 7 for correcting characteristics. The frequency band dividing circuit 4 calculates the linear phase F assigned to each frequency band.
A plurality of frequency band dividing circuits 4 ₁ , 4 ₂ ,..., 4 _n composed of IR type filters are provided. Digital high-pass filter 6, a plurality of digital high-pass filter ₆₁ which is assigned to each frequency band, 6 _2, ... 6 comprises a _n, each speaker unit 3 ₁ in each digital high pass filter 6 ₁ to 6 _n, 3 _2, ... to limit the input of a low frequency band to 3 _n. The characteristic correction inverse filter 7 includes a plurality of characteristic correction inverse filters 7 ₁ , 7 ₂ ,... 7 _n composed of non-linear phase FIR filters assigned to each frequency band, and the characteristic correction inverse filters 7 ₁ to 7 _n. 7 _n are provided with a plurality of inverse filter coefficient generating circuits 7 ₁₁ , 7 _{22 ,.} Each characteristic correction inverse filter 7 ₁ to _7-n is, the coefficient data from the inverse filter coefficient generating circuit 7 ₁₁ to _7-nn, performs real-time convolution operation on the output signals from the digital high-pass filter 6 ₁ to 6 _n . That is, each inverse filter coefficient generation circuit 7 _{11 to} 7 _nn
It is the inverse filter 7 ₁ to _7-n for characteristic correction, an arithmetic means for providing a filter coefficient. Each inverse filter coefficient generation circuit 7 ₁₁
By given filter coefficients from to _7-nn, inverse filter 7 to 7 _n for each characteristic correction, the speaker units 3 _1, 3 _2, has an inverse characteristic of the sound pressure frequency characteristics of ... 3 _n,
By performing the convolution operation, a digital signal whose characteristic has been corrected in order to realize the flattening of the amplitude characteristic of the total transmission frequency characteristic of each channel and the linearization of the phase frequency characteristic is generated.

The operation of this embodiment will be described. First, the frequency band division circuit 4 ₁ to 4 _n is a digital signal inputted to the digital channel divider, divides each desired frequency band. Next, each of the digital high-pass filter 6 ₁ to 6 _n is an output signal from each frequency band division circuit 4 ₁ to 4 _n, blocking frequencies below the signal minimum resonance frequency of the speaker unit 3 ₁ to 3 _n. Each of the characteristic correction inverse filters 7 to 7 _n is connected to each of the inverse filter coefficient generation circuits 7 ₁₁ to 7 ₁₁ .
The coefficient data from 7 _nn, performs real-time convolution operation on the output signals from the digital high-pass filter 6 ₁ to 6 _n, generates a characteristic corrected digital signal. The digital signal whose characteristics have been corrected is supplied to each D / A conversion circuit 5.
After being converted to an analog signal by _{1 to} 5 _n , the power amplifier 2
₁ is guided via to 2 _n in each speaker unit 3 ₁ to 3 _n are converted.

[0012] In other words, the coefficient generating circuit 7 ₁₁ - for each inverse filter
As 7 _nn coefficient data, each speaker units 3 _1,
3 _n sound pressure coefficient data gives the inverse characteristic of the frequency characteristic or the system (each speaker unit to the digital signal is input to reach the final microphone 20, of 3 ₁
３3 _n to the microphone 20 for sound propagation time t ₁ ,
t ₂ ,... t _n ) are set to coefficient data that gives the inverse characteristic of the total transmission frequency characteristic excluding the digital high-pass filter 6 and the characteristic correction inverse filter 7. Accordingly, the frequency characteristic of the analog signal characteristic corrected by the characteristic correction inverse filter 7, the speaker units 3 _1,
The _3n sound pressure frequency characteristics are mutually corrected.

In short, according to the first embodiment, each of the characteristic correction inverse filters 7 to 7 _n uses the coefficient data from each of the inverse filter coefficient generation circuits 7 _{11 to} 7 _nn to generate each of the digital high-pass filters 6 _{1 to} 6 _n. A digital signal whose characteristics have been corrected in order to realize the real-time convolution of the output signal from _n to flatten the amplitude characteristics of the total transmission frequency characteristics of each frequency band and to linearize the phase frequency characteristics. by that produce, for each speaker unit 3 ₁ to 3 _n lowest resonance frequency or higher are realized sound pressure flat, the phase linearity, faithful transmission of the acoustic signal, it is possible to realize reproduction.

[0014] This point will be described with reference to FIG. 2, the sound pressure frequency characteristic of the speaker unit 3 ₁ to 3 _n 31 is generally sound pressure level in the low frequency range is reduced. Therefore, the form in which inevitably increases the sound pressure level of the low frequency range as the characteristic correction inverse filter 7 ₁ to _7-n of the frequency characteristic 32.
As a result, the provision of the inverse filter 7 ₁ to _7-n for each characteristic correction, the speaker unit 3 ₁ to 3 _n of the electrical impedance characteristic 33 is rapidly increased in a low frequency range of each speaker unit 3 ₁ to 3 _n This results in damage.

[0015] For these reasons, to limit the excessive input to the speaker unit in the low frequency range in the digital high-pass filter 6 ₁ to 6 _n. In particular, the cut-off frequency of the digital high-pass filter 6 is
By selecting near the lowest resonance number of _{1 to} 3 _n , the input level in the low frequency range sharply drops, and the speaker unit 3
Excessive input to _{1 to} 3 _n can be efficiently suppressed.

[0016] As described above, the inverse filter 7 _1-7 for each of the digital high-pass filter 6 ₁ to 6 _n and the characteristic correction
_By providing _n as a component of the digital channel divider 10, it is possible to simultaneously achieve faithful reproduction of an audio signal and prevention of excessive input.

The same operation and effect can be obtained even if the order of arrangement of the frequency band dividing circuit 4 and the characteristic correction inverse filter 7 is changed.

Embodiment 2 FIG. FIG. 3 is a block diagram of the second embodiment, which is characterized in that the digital channel divider 10 is provided with a high-pass / characteristic correction inverse filter 67 in which the digital high-pass filter 6 and the characteristic correction inverse filter 7 are integrated. Pass / characteristic correction inverse filter 67 has a plurality of high-pass / characteristic correction inverse filter 67 ₁ assigned to each frequency band, 67 _2, ... 67 and _n, each high-pass / characteristic correction inverse filter _67i to 674 a plurality of high-pass / inverse filter coefficient generating circuit 67 ₁₁ assigned to each _n, 67 _22, ... 67
_nn .

This integration means that the high-pass / characteristic correction inverse filters 67 _{1 to} 67 _n correspond to the digital high-pass filters 6 supplied from the high-pass / inverse filter coefficient generation circuits 67 _{11 to} 67 _nn. The coefficient data and the coefficient data corresponding to the inverse filter coefficient generation circuits 7 ₁₁ , 7 ₂₂ ,... 7 _nn are convolution-operated in advance, and the convolution operation is performed as new coefficient data.

Embodiment 3 FIG. FIG. 4 is a block diagram of the third embodiment. The digital channel divider is a frequency band division / high-pass / characteristic correction inverse filter 467 in which a frequency band division circuit 4, a digital high-pass filter 6, and a characteristic correction inverse filter 7 are integrated. It is characterized by being formed by. Frequency band dividing circuit / high-pass / inverse filter 467 for characteristic correction
Are a plurality of frequency band division circuits / high-pass / characteristic correction inverse filters 467 ₁ ,
467 _2, ... 467 _n and each frequency band dividing circuit / high pass / characteristic correction inverse filter 467 _1, ～467 plurality allocated to every _n filter / high pass / inverse filter coefficient generation circuit 467 _11, 467 _22, ... 467 _nn .

This integration means that each frequency band division circuit / high-pass / characteristic correction inverse filter 467 ₁ , 467 ₂ ,... 4
67 _n , the filter coefficient data corresponding to the frequency band dividing circuit 4 and the filter coefficient data corresponding to each digital high-pass filter 6 supplied from each filter / high-pass / inverse filter coefficient generation circuit 467 _{11 to} 467 _nn. previously convolution operation and coefficient data corresponding to the respective inverse filter coefficient generating circuit 7 ₁₁ to _7-nn, is to perform convolution calculation result of the operation as a new coefficient data.

[0022]

[Effects of the Invention] As described above, the digital channel divider of the present invention converts the input signal for each frequency band.
Digital frequency band splitter for splitting into multiple signals
When the digital highpass to reduce overall sound and planarization and characteristic correction inverse Fi <br/> Le data for performing linearization of the phase frequency characteristic of the pressure frequency characteristic of the speaker unit, the input of the following minimum resonance frequency of the speaker unit With the provision of the filter, it is possible to realize faithful reproduction of the acoustic signal in the speaker unit and to prevent application of an excessive input to the speaker unit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing electro-acoustic characteristics of the speaker unit of Example 1 with respect to sound pressure frequency characteristics and electric impedance.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a third embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional multi-amplifier type speaker system.

[Explanation of symbols]

 2,2₁, 2_Two, ... 2_n Power amplifier 3,3₁, 3_Two, ... 3_n Speaker uni
4,10 Digital tea
Nungul Divider 4₁, 4_Two, ... 4_n Frequency band division
Circuit 5,5₁, 5_Two, ... 5_n D / A conversion circuit 6,6₁, 6_Two, ... 6_n Digital high
Pass filter 7, 7₁, 7_Two, ... 7_n Reverse for characteristic correction
Filter 7₁₁, 7_{twenty two}, ... 7_nn  Inverse filter coefficient
Generation circuit 20 Microphones 67, 67₁, 67_Two, ... 67_n High pass / characteristic
Inverse filter for correction 67₁₁, 67_{twenty two}, ... 67_nn High Pass / Reverse
Filter coefficient generation circuit 467, 467_1,467_2,... 467_n Frequency band division
Circuit / High-pass / Inverse filter 467_11,467_{twenty two,}…_,467_nn Filter / High
Pass / Inverse filter fill Data generation circuit t₁, T_Two, ... t_n Speaker uni
Microphone to microphone Sound propagation time in

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-51-135298 (JP, A) JP-A-57-113693 (JP, A) JP-A-2-122798 (JP, A) JP-A-60-1985 204198 (JP, A) JP-A-63-42599 (JP, A) JP-A-62-216493 (JP, A) JP-A-1-175497 (JP, A) Japanese Utility Model Laid-Open No. 59-101527 (JP, U) Japanese Utility Model Showa 62-181093 (JP, U)

Claims (5)

(57) [Scope of request for utility model registration] 1. A and digital subband circuit for dividing the input digital signal into a signal of each frequency band, the characteristic correction inverse filter to provide an inverse characteristic of a sound pressure frequency characteristic of the speaker units, the speaker It has a cut-off frequency that almost matches the lowest resonance frequency of the unit.
One digital high-pass filter and speakers for digital channel divider, characterized in that the painting Bei. 2. A digital channel divider for a speaker according to claim 1, wherein a nonlinear phase FIR filter is provided as an inverse filter for characteristic correction. As 3. A characteristic of the inverse filter for characteristic correction relates system of each channel to the digital signal is input to reach the final Makurohon, de I digital high-pass filter and characteristics correction inverse filter 2. The method according to claim 1, wherein an inverse characteristic of the total transmission frequency characteristic is given.
3. The digital channel divider for a speaker according to any one of 2. 4. By convolving the coefficient data of the inverse filter and the digital high-pass filter characteristic correction, characterized by forming an inverse filter for high-pass / characteristic correction integrating the inverse filter and the digital high-pass filter characteristic correction The digital channel divider for a speaker according to any one of claims 1 to 3, wherein 5. By convolving the coefficient data of the inverse filter and the digital high-pass filter for frequency band division circuit and characteristic correction, frequency band division circuit and the characteristic correction inverse filter and digital high-pass filter the integrated frequency band division / 4. A high-pass / characteristic correcting inverse filter is formed.
4. A digital channel divider for a speaker according to any one of the above.