JPS59161908A - Compensator for requency characteristics - Google Patents

Abstract

PURPOSE:To attain an automatic correction of the overall frequency characteristics by selecting and extracting successively the signals sent from each frequency band with a single A/D converter and at the same time controlling a frequency characteristic control circuit based on the information obtained after the A/D conversion. CONSTITUTION:A selector 13 selects a pink noise generator 11 when the frequency characteristics are compensated. The level of each frequency band is controlled independently of each other by a frequency characteristics control circuit 14 and supplied to a selector 23 via a sound 19. It is possible to decide the selection of the field 19 through the selector 23. The frequency band signals supplied from filter circuits 241-24n and wave detecting circuits 251-25n are selected successively by a selector 26 and converted into the digital information by an A/D converter 27. This digital information is compared with the desired frequency characteristic information stored in a memory 29 through arithmetic controller 28. Here a signal is produced to control the frequency characteristics of the circuit 14. Thus it is possible to perform an automatic correction to the desired frequency characteristics including the field 19.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a frequency characteristic correction device, which measures the acoustic characteristics of a sound field and, based on the results, adjusts the acoustic signals independently from each other in each of a plurality of divided frequency bands. The present invention relates to a correction device that automatically corrects the frequency characteristic to a desired frequency characteristic by level-enhancing or level-attenuating the frequency characteristic.

Prior Art FIG. 1 shows a block diagram of an example of a conventional frequency characteristic correction device. In the figure, noise (with constant energy per octave) extracted from pink noise generator 1 (
The so-called pink noise) is supplied through a graphic equalizer 2 to an amplifier 3, where it is amplified and then sounded by a speaker 5 arranged in a sound field 4 such as a listening room. The sound emitted from the speaker 5 into the sound field is collected by the microphone 6 and converted into an electrical signal (acoustic signal), and then passed through n band filters 71 to 7n having different pass frequency bands. supplied in parallel, n
The frequency band is divided into - frequency components. Each frequency component extracted from the bandpass filters 71 to 7n is supplied to A, D converters 91 to 9n through detection circuits 81 to 8n, where it is converted into a digital signal and then supplied to the digital arithmetic processing unit 10. .

The digital arithmetic processing device 10 controls the level of each resonance point of the graphic equalizer 2 so that the result of frequency characteristic measurement becomes a desired frequency characteristic. Here, the graphic equalizer 2 latches the data signal out of the output address signal and data signal of the digital arithmetic processing device 10 using a latch pulse obtained by decoding the address signal, and transmits the latch output to n DA converters. The configuration is such that the corresponding - of the n switches is turned on or off through a predetermined DA converter of -, and the - of the n resonance points is brought into a peak state or a dip state. There is.

As another example of the conventional device, in place of the AD converters 91 to 9n, a comparator is provided on the n side to compare the reference voltage and the output detection voltage of each of the detection circuits 81 to 8n. There is also a device configured to control the counting direction of a corresponding reversible counter among the n reversible counters, and supply the output of the reversible counter obtained by counting the clock to the DA converter in the graphic equalizer 2. .

Problems to be Solved by the Invention However, the conventional frequency characteristic correction device shown in FIG.
There is a problem in that n AD converters 91 to 9n and n DA converters are required in the graphic equalizer 2, which are extremely expensive. Furthermore, the conventional frequency characteristic correction device using a comparator requires a generator that generates a reference voltage, and furthermore, each of the n types of reference voltages must be manually adjusted to correct the desired frequency characteristics. Not,
There are problems in that correction takes time and it is difficult to easily obtain desired frequency characteristics.

Furthermore, in other conventional frequency characteristic correction devices, the frequency characteristic to be corrected is, for example, only a flat characteristic,
There was a problem that automatic correction to desired frequency characteristics was not possible.

Therefore, the present invention sequentially selects and outputs frequency components of a plurality of divided frequency bands using a selector, supplies them to an arithmetic and control unit through a single AD converter, and sequentially variably controls the value of an electronically controlled variable resistance element. It is an object of the present invention to provide a frequency characteristic correction device that solves the above problems by automatically outputting a signal.

Means for Solving the Problems The present invention provides a generator for generating a signal for measuring frequency characteristics;
A frequency characteristic control circuit in which level characteristics in a plurality of mutually different frequency bands are independently and variably controlled for each frequency band by an external control signal; 2. A microphone for converting the sound emitted from this speaker into an electrical signal, and a means for dividing the electrical signal from the microphone into a plurality of mutually different frequency bands and detecting each divided frequency band. A circuit for obtaining a signal, a selector that sequentially selects and outputs detection signals of the plurality of frequency bands, a single AD converter that performs AD conversion of the output detection signal of the selector, and information regarding various frequency characteristics to be corrected. A storage device that stores the frequency characteristic of 0 in the form of a digital signal, a digital signal related to the frequency characteristic of - arbitrarily selected from the storage device, and a digital signal from the AD converter are respectively supplied, and the error between both digital signals is calculated by calculation. and an arithmetic and control device that generates and outputs a control signal for varying the frequency characteristics of the frequency characteristic control circuit so as to substantially eliminate errors, and determines the frequency of the transmission path of the acoustic signal including the acoustic characteristics of the sound field having the speaker and the microphone. The present invention is configured to automatically correct the characteristic to the arbitrarily selected - frequency characteristic, and one embodiment thereof will be described below with reference to the drawings.

Embodiment FIG. 2 shows a block system diagram of an embodiment of the frequency characteristic correction device according to the present invention. In the same figure, pink noise generator 1
The pink noise generated and output from the sound source 1 and the acoustic signal extracted from the sound source 12 are supplied to a selector 13, respectively.

The selector 13 is controlled by a signal from an arithmetic and control unit 28, which will be described later, to selectively output pink noise during frequency characteristic correction. The signal selected and output by the selector '13 is supplied to the frequency characteristic control circuit 14, where the level is independently controlled for each of n different frequency bands set in advance, thereby changing the frequency characteristic. Variably controlled. The frequency characteristic control circuit 14 is composed of an amplifier 15, n electronically controlled variable resistance elements 161 to 16n, and n LCR resonance circuits 171 to 17n. It is said to be composed of

As shown in FIG. 3, the amplifier 15 includes a resistor Ra.

It is composed of an operational amplifier 34 and a resistor Rb.

Furthermore, n variable resistance elements 16 are connected between a connection terminal 36 between the resistor Ra and the non-inverting input terminal of the operational amplifier 34, and a connection terminal 37 between the resistor Rb and the inverting input terminal of the operational amplifier 34.
+ to 16n are connected in parallel. Further, the variable resistance elements 161 to 16n are connected to LCR resonance circuits 171 to 17n, respectively.
are connected separately. The resonance frequencies of the resonance circuits 171 to 17n are selected from n different resonance frequencies within the audible frequency band. Furthermore, 33 is an input terminal, and 35 is an output terminal.

The variable resistance elements 161 to 16n described above each have the same configuration, and are represented by an equivalent circuit as shown in FIG. 4, for example. As shown in FIG. 4, the i-th negative variable resistance element 16i has 2m resistors R1 to R21R connected in series between terminals 36 and 37, and one end connected to one end of the resistors R1 to R2m. 2m open/close switches St"-82111 whose other ends are commonly connected to the terminal 39, and resistors Rm and RIl.
It consists of a - opening/closing switch SO connected between the connection point with lH and the terminal 39, and resistors Rm' and RI11+,
The connection point with is further connected to a terminal 38. terminal 38
is grounded, and the terminal 39 is connected to the corresponding - LCR resonant circuit 1.
71 (not shown). Opening switch SO
And in S1 to S82111, only one of the switches is closed and the other switches are opened according to a control signal from the calculation side t11 device 28. Thereby, the variable resistance element 16i has a configuration similar to that of a variable resistor in which the terminals 36 and 37 are fixed terminals, the terminal 38 is a zenter tap terminal, and the terminal 39 is a slider terminal.

The frequency characteristic control circuit 14 controls the frequency fi (which is a narrow band centered around the resonant frequency of the LCR resonant circuit 171, which exhibits a predetermined level characteristic of a flat frequency characteristic when the switch SO is closed). , when any - switch is opened in the 81 direction from switch 3m, a level attenuation characteristic is shown in which the amount of attenuation gradually changes, and on the other hand, the - switch among switches Sm++ to 82m is sequentially switched in the Szm direction. and gradually shows great level enhancement characteristics.

At the time of frequency characteristic correction, pink noise is selected and outputted from the selector 13, and after the frequency characteristic is controlled by the frequency characteristic control circuit 14 having the above configuration, it is supplied to the speaker 20 in the sound field 19 such as a listening room through the power amplifier 18. , pronounced from this. The sound emitted from the speaker 20 is collected by a microphone 21 in a sound field 19 and converted into an electric signal (acoustic signal), and then sent to a selector 23 through a variable gain amplifier 22 configured to be able to vary the gain. Supplied.

The selector 23 is configured to selectively output either one of the output signals of the frequency characteristic control circuit 14 and the variable gain amplifier 22, and is configured to selectively output one of the output signals of the frequency characteristic control circuit 14 and the variable gain amplifier 22.
The output signal of the variable gain amplifier 22 is controlled to be selectively outputted by a control signal from the variable gain amplifier 22. Therefore, when correcting the frequency characteristics, the selector 23 extracts the electrical signals that have been acousto-electrically converted by the microphone 21 and amplified by the variable gain amplifier 22, and outputs n electrical signals having n narrow passband characteristics different from each other. Filter circuits 241-2
4n, where they are divided into frequency components of n frequency bands.

The center frequencies of the passband widths of the fill circuits 241 to 24n are made equal to the respective resonance frequencies of the L'CR resonance circuits 171 to 17n.

Each frequency component of the n divided frequency bands extracted from the filter circuits 241 to 24n is transmitted to the detection circuits 251 to 25.
After being detected by n, the signal is supplied to the selector 26. The selector 26 is controlled by a control signal from the arithmetic and control unit 28 to sequentially and cyclically select and output only the - detection signals from the output detection signals of the detection circuits 251 to 25n during frequency characteristic correction, and output the output detection signals to the AD. Output to converter 27.

For example, as shown in FIG. 5, the AD converter 27 connects buffer amplifiers 421 to 42k to a ladder-shaped resistor network consisting of resistors with resistance values R and 2R,
By sequentially and cyclically applying a reference voltage to the buffer amplifiers 421 to 42, a staircase wave with a constant period is outputted from the ladder resistor network and applied to one input terminal of the comparator 41, and the other input terminal of the comparator 41 is The detection signal (analog signal) from the selector 26 is input to the input connector 40.
The structure is such that the voltage is applied. That is, the staircase wave taken out from the known ladder-type DA conversion circuit and the selector 26
The comparator 41 compares the levels of the detected signals of the detected signals, respectively, and the comparator 41 outputs a signal of a predetermined polarity at a time timing corresponding to the detected signal level and outputs it to the arithmetic and control unit 28.

The arithmetic and control unit 28 is composed of, for example, a microcomputer, and adjusts the detected signal level for each divided frequency band based on the input timing of a digital signal of a predetermined logical value extracted from the AD converter 27 at a time timing corresponding to the detected signal level. The acoustic characteristics (frequency characteristics) of the sound field 19 are measured. In due course, the arithmetic and control unit 28 receives a digital signal indicating a frequency characteristic (for example, a flat frequency characteristic) arbitrarily selected from among a plurality of frequency characteristics stored in advance in the memory 29, and a digital signal from the AD converter 27. Comparing the digital signals related to the frequency characteristics of the sound field 19, if there is an error between the two, a control signal is generated to control the level in the direction of eliminating the error in the frequency band with the error, and the electronic control type Variable resistance element 161
~16n to the corresponding one or more variable resistance elements.

FIG. 6 is a flowchart showing the above-mentioned operation of the arithmetic and control unit 28, in which the frequency characteristics of the sound field are measured (step 43).
, and then detect whether the frequency characteristics of the sound field 19 match the desired frequency characteristics inputted from the memory 29 (Step 44). If there is an error, a correction value is calculated by calculation, and the calculation result is A control signal based on is generated to variably control the resistance values of the variable resistance elements 16+ to 16n, that is, the frequency characteristics of the frequency characteristic control circuit 14 (step 45). Thereafter, by repeating the same operation as above, the overall frequency characteristic consisting of the frequency characteristic of the sound field 19 and the frequency characteristic of the signal transmission system of this device is changed to the desired negative frequency characteristic selectively inputted from the memory 29. can be corrected so that it approximately matches. This frequency characteristic correction operation can be performed automatically, quickly and accurately by the arithmetic and control unit 28. FIG. 7 shows the frequency characteristics that can be corrected by the device of the present invention, and the frequency characteristics can be corrected to any desired frequency characteristics within the frequency characteristic ranges indicated by ■ and ■.

The output detection signals of the detection circuits 251 to 25n are simultaneously supplied to the display control circuit 30, where they undergo predetermined signal processing necessary for display, and then supplied to the display device 31 for display. Therefore, if the output signal of the selector 23 is switched to the output signal of the frequency characteristic control circuit 14 after automatically correcting the desired frequency characteristic inputted from the memory 29 as a flat characteristic, the sound field 19
The display device 31 can display the frequency characteristics necessary to make the frequency characteristics flat.

Note that by switching the selector 13 to a selective output state of the acoustic signal from the sound source 12 after the automatic correction of the frequency characteristics, it is possible to enjoy sound in the sound field 19 to which the desired frequency characteristics are accurately imparted. Also at this time, selector 2
3 to the output signal selection output state of the frequency characteristic control circuit 14, the frequency characteristic of the next acoustic signal can be checked on the display device 31.

Note that the selector 23 may be configured to be able to selectively output the output signal of the selector 13 as well.

Effects As described above, according to the present invention, the frequency characteristics of the frequency characteristic control circuit to which a frequency characteristic measurement signal such as pink noise is supplied is digitally calculated based on the frequency characteristic of the sound field calculated by the arithmetic control device. Since the structure is configured to perform variable control over the frequency characteristics of the sound field and the frequency characteristics of the device, the total frequency characteristics of the sound field and the frequency characteristics of the device can be automatically and quickly and accurately corrected so that they substantially match the desired frequency characteristics. Furthermore, by changing the frequency characteristics from the storage device that is input to the arithmetic and control unit, the frequency characteristics to be corrected can be easily changed arbitrarily, and the detected signals obtained for each of the multiple divided frequency bands can be selected. Since the detection signal level is sequentially and cyclically switched and outputted, A to AD convert the detected signal level.
It has the advantage that only one D converter is required and it can be constructed at a lower cost than in the past.

[Brief explanation of drawings]

Fig. 1 is a block system diagram showing an example of a conventional device, Fig. 2 is a block system diagram showing an embodiment of the present invention device, and Fig. 3 is an implementation of the frequency characteristic control circuit in the block system shown in Fig. 2. FIG. 4 is an equivalent circuit diagram of an example of the variable resistance element indicated by - in FIGS. 2 and 3. FIG. A circuit diagram showing one embodiment, FIG. 6 is a flowchart for explaining the operation of one embodiment of the arithmetic and control device in the program system shown in FIG. 2, and FIG. 7 shows the frequency characteristics of the device of the present invention. It is a diagram. 1.11...Pink noise generator, 2...Graphic equalizer, 5.20...Speaker, 6,21.
...Microphone, 10...Digital arithmetic processing unit, 12...Sound source, 13.23.26...Selector, 14...Frequency characteristic control circuit, 161-16n...
・Electronically controlled variable resistance element, 17+ to 17n...LC
R resonance circuit, 22... variable gain amplifier, 24+~24
n... Filter circuit, 251-250... Detection circuit, 27... AD converter, 28... Arithmetic control device, 2
9...Memory, 30...Display control circuit, 31...
Display device, 34... operational amplifier, 41... comparator. Figure 4 1 Figure 6

Claims (1)

[Claims] (1) A generator that generates a frequency characteristic measurement signal, a frequency characteristic control circuit in which the level characteristics in a plurality of mutually different frequency bands are variably controlled independently for each frequency band by an external control signal, and the frequency means for producing the frequency measurement signal passed through the characteristic control circuit through a speaker; a microphone for converting the sound produced by the speaker into an electrical signal; and a means for converting the electrical signal from the microphone into a plurality of different frequency bands. A circuit that divides and obtains a detection signal for each divided frequency band, a selector that sequentially selects and outputs the detection signals of the plurality of frequency bands, and a single AD converter that performs AD conversion of the output detection signal of the selector. A storage device that stores information regarding various frequency characteristics to be corrected in the form of digital signals, and a digital signal regarding an arbitrarily selected frequency characteristic from the storage device and a digital signal from the AD converter are respectively supplied. and an arithmetic control device that calculates the error between the two digital signals by arithmetic operations and generates and outputs a control signal for varying the frequency characteristic of the frequency characteristic control circuit so that the error is substantially eliminated;
A frequency characteristic correction device that automatically corrects the frequency characteristic of an acoustic signal transmission path including the acoustic characteristic of a sound field having the speaker and the microphone so as to have the frequency characteristic of the arbitrarily selected -. . ■ A generator that generates a frequency characteristic measurement signal, a frequency characteristic control circuit in which the level characteristics in a plurality of mutually different frequency bands are independently and variably controlled for each frequency band by an external control signal, and the frequency characteristic control circuit. means for emitting the frequency measurement signal passed through the circuit through a speaker; a microphone for converting the sound emitted from the speaker into an electrical signal; a variable gain amplifier for amplifying the output electrical signal of the microphone; switching means for selectively outputting one of the acoustic signal, the output signal of the frequency characteristic control circuit, and the output signal of the variable gain amplifier; a circuit for dividing and obtaining a detected signal for each divided frequency band; a selector for sequentially selecting and outputting the detected signals of the plurality of frequency bands when the switching means selectively outputs the output signal of the variable gain amplifier; A single AD converter that AD converts the output detection signal of the selector, a storage device that stores information regarding various frequency characteristics to be corrected in the form of digital signals, and an arbitrarily selected one from the storage device. A digital signal related to the frequency characteristic and a digital signal from the AD converter are respectively supplied, the error between the two digital signals is calculated by calculation, and a control signal for varying the frequency characteristic of the frequency characteristic control circuit is generated and outputted so that the error is substantially eliminated. and a display means for displaying the detected signals of the plurality of frequency bands, respectively, and the frequency characteristics of the acoustic signal transmission path including the acoustic characteristics of the sound field having the speaker and the microphone are arbitrarily selected. A frequency characteristic correction device characterized in that the frequency characteristic correction device automatically corrects the frequency characteristic so as to have a frequency characteristic of -.