JP2528993B2 - Frequency characteristic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention can set and control an equalizing curve commonly for the front and rear sides, or can independently set and control an equalizing curve for the front and rear sides. The present invention relates to a frequency characteristic control device.

<Prior Art> In a vehicle audio system or a surround system, a large number of amplifiers and speakers are provided in front, rear, left and right. In such an audio system, an equalizer (frequency control device) is becoming an important position for enjoying sound, and the number of adjustable bands is increased, and the equalizing curve is independently set on the front side and the rear side. The number of users who are enjoying the finer sound creation is increasing.

<Problems to be Solved by the Invention> In terms of sound production, it is best to provide an equalizer independently on the front side and the rear side, but since two equalizers are required, it becomes expensive and large in size. ,
Especially, it is not suitable for a car audio system which is placed in a limited narrow space in a vehicle.

Therefore, a method is generally used in which one equalizer is used and the equalizer curves set by the equalizer are used as front and rear equalizing curves. This method has the advantage of being small and inexpensive because only one equalizer is required, but the equalizing curve cannot be set independently for the front and rear.

There is also a system called a dual equalizer. In this method, half of the characteristic setting switches in one equalizer are used for setting the equalizing curve on the front side,
The rest is used for setting the rear side equalizing curve, the front side equalizing curve is displayed on one of the left and right sides of the display unit, and the rear side equalizing curve is displayed on the other side. However, with a dual equalizer, it is difficult to set the band in detail in terms of space, and in the car audio system, at most 5-6 bands on the front side and 5 bands on the rear side
About 6 bands are common, and the number of adjustable bands is small.

From the above, an object of the present invention is to provide a frequency characteristic control device capable of setting the same equalizing curve on the front side and the rear side in an appropriately increased number of bands, or setting the equalizing curve independently on the front side and the rear side. That is.

<Means for Solving the Problems> In the present invention, the above problems are a characteristic setting switch for setting an equalizing curve (frequency characteristic), a mode selection switch for selecting an equalizing control mode,
Equalizing curve display unit, control unit that outputs coefficient data and frequency characteristic value (gain of each band) according to the equalizing control mode, and performs predetermined digital processing on audio data using the coefficient data and frequency characteristic value, This is achieved with a digital signal processor (DSP) that outputs four channels of front, rear, left and right audio signals.

<Function> The first mode in which all characteristic setting switches are used for equalizing curve setting common to the front and rear sides, and half of the characteristic setting switches are used for front side equalizing curve setting, and the rest are used for rear side equalizing curve setting. In the first mode, the display section displays the set equalizing curve common to the front side and the rear side. In the second mode, the equalizing curve on the front side and the equalizing curve on the rear side are set. Respectively, and the DSP performs predetermined digital processing on the digital audio data of the L channel and the R channel by using the coefficient data according to the selected mode and the set frequency characteristic value (gain of each band). 4 channels (front L channel, front R channel Audio signals of the rear, rear L channel, and rear R channel) are output.

<Embodiment> FIG. 1 is a block diagram of a frequency characteristic control device according to the present invention. 10 is a low-pass filter to which L-channel and R-channel audio signals Sl and Sr are input via an analog input terminal AIN. Is an AD converter for L channel and R channel, 12 is a digital interface circuit for performing predetermined processing on audio data input through the digital input terminal DIN, and outputting, 12 'is for receiving digital audio data or analog A switch that switches the input signal according to whether it receives an audio signal, 13 is a digital signal processor (DSP), 14fl,
14fr, 14rl, 14rr are DA converters for front L channel, front R channel, rear L channel, rear R channel, and 15fl, 15fr, 15rl, 15rr are front L channel, front R channel, rear It is a low-pass filter for the L channel and the rear R channel, and outputs the audio signals Sfl.Sfr, Srl, Srr.

Reference numeral 16 is a control microcomputer, which has coefficient data Ai to Ei (i = 1 to 1) according to two equalizing modes described later.
2), Aj to Ej (j = 1 to 6) are stored, and equalizing curves (frequency characteristics) FC1; FC2, FC2 'in each set mode are stored, and coefficients corresponding to the selected equalizing mode are stored. The data and the set frequency characteristic value (gain of each band) are output to DSP13, and the display control of the equalizing curve is performed.

Reference numeral 17 denotes an operation panel, which has an operation unit 17a and a display unit 17b that displays an equalizing curve. Operating part 17a
The mode selection key IM to select the equalizing mode
S and a characteristic setting switch BSi (i = 1 to 12) for setting the frequency characteristic (gain) in each band are provided.

There are a first mode and a second mode in the equalizing mode, and the first mode is all characteristic setting switches BS1 to BS12.
Is a mode to set the same equalizing curve on the front side and the rear side using the second mode, half of the characteristic setting switches BS1 to BS6 are used for setting the equalizing curve on the front side, and the rest (BS7 to BS12) are on the rear side. The mode selection switch IMS determines which mode is used for frequency control, and which mode is used for frequency control. In the first mode, the display section 17b displays an equalizing curve FC1 with 12 bands set commonly on the front side and the rear side as shown in FIG. 2 (a), and in the second mode, as shown in FIG. Display section as shown in (b)
A front side equalizing curve FC2 with six bands is displayed on the left side of 17b, and a rear side equalizing curve FC2 ′ with six bands is displayed on the right side.

In the first mode, the characteristic setting switches BS1 to BS12 have center frequencies of 31.5, 63, 125, 190, 250, 500 Hz,
Set the gain in the 1K, 1.5K, 2.2K, 4.5K, 9K and 18KHz bands (see Fig. 2 (a)), and in the second mode, the characteristic setting switches BS1 to BS6 are for setting the equalizing characteristics on the front side. , Center frequency 63, 400, 800H respectively
Set the gain in the z, 1.8K, 4K, 10KHz band,
The characteristic setting switches BS7 to BS12 are for setting the equalizing characteristics on the rear side, and the center frequencies are 63, 400, 800H, respectively.
Set the gain in the z, 1.8K, 4K, and 10KHz bands.

The DSP 13 performs a predetermined equalizing process on the digital audio data of the L channel and the R channel by using the coefficient data and the frequency characteristic value (gain of each band) according to the selected equalizing mode, and the four channels (front L Channel, front R channel, rear L channel, rear R channel) audio signal Sf
It outputs l ', Sfr', Srl ', Srr'.

FIGS. 3 and 4 are signal flow diagrams of the DSP in the 12-band equalizing process. In FIG. 3, reference numeral 21 is an adder, and 22 _{01 to} 22 ₁₂ are band component extractors, which perform the arithmetic processing shown in FIG. 4, respectively. In FIG. 4, 41 to 44 are 1-sampling time delay units, 45 to 49 are multiplication units for multiplying coefficient data Ai to Ei, and 50 is an addition unit.
The coefficient data Ai to Ei are the center frequencies of the bands,
It depends on the sharpness (Q), the gain, etc., is necessary for each gain step, and is preset and stored in the memory of the control microcomputer 16. For example, if the gain is +
If it is a 2 dB step from 12 dB to -12 dB, +12,10,8, ...
・ 13 steps of 2,0, −2, −4, ..., − 10, −12
2 (band) x 13 (step) = 156 sets of coefficient data are required.

Therefore, 12 sets of coefficient data Ai to Ei (i = 1 to 12) are stored by the number of gain steps in the first mode of the front and rear common 12 bands, and in the second mode of the front and rear independent 6 bands respectively. Six sets of coefficient data Aj to Ej (j = 1 to 1
6) is stored in the memory of the microcomputer 16 by the number of gain steps, and predetermined coefficient data is input to the DSP 13 according to the selected equalizing mode and the set gain.

The process of the present invention will be described below with reference to the flowchart of FIG.

The microcomputer 16 checks whether the mode set by the mode selection key IMS is the first mode (12 band mode common to front and rear) or the second mode (6 band mode independent to front and rear). (Step 10
1).

In the first mode, the characteristic setting switch BSi (i = 1
Up to 12) the gain Gi (i = 1 to 12)
Front and rear common 12-band coefficient data Ai to Ei (i
1 to 12) are input to the DSP 13, and the display section 17b is used to display the equalizing curve FC1 common to the front and rear of 12 bands as shown in FIG. 2 (a) (step 1
02).

When the coefficient data is input, the DSP 13 uses these coefficient data Ai to Ei (i = 1 to 12) for the L channel audio signal Sl and the R channel audio signal Sr as shown in FIGS. 3 and 4, respectively. By performing the calculation shown below, the front L channel audio signal Sfl ′, the front R channel audio signal Sfr ′, and the rear L channel audio signal Sr
The l'and rear R channel audio signals Srr 'are output to the DA converters 14fl, 14fr, 14rl and 14rr, respectively (step 103).

On the other hand, if the mode selected in step 101 is the second mode, the microcomputer 16 causes the characteristic setting switch BS
The coefficient data Aj to Ej (coefficient data of front / rear independent 6-band mode) corresponding to the gain set to i (i = 1 to 12) is input to the DSP 13 and the second data is displayed on the left side of the display unit 17b. As shown in Figure (b), the equalizing curve FC2 for the front 6 bands is displayed, and the equalizing curve FC2 'for the rear 6 bands is displayed on the right (step 1
04).

The setting values of the characteristic setting switches BS1 to BS6 are used as the gain on the front side, the setting values of the characteristic setting switches BS7 to BS12 are used as the gain on the rear side, and the coefficient data Aj to Ej are used.
(J = 1 to 6) are commonly used on the front side and the rear side.

When the coefficient data and the gain are input, the DSP 13 uses the coefficient data Aj to Ej (i = 1 to 6) to perform the calculation shown in FIGS. 3 and 4 on the L channel audio signal Sl, respectively. Front L channel audio signal Sf
l ', front R channel audio signal Sfr' is DA
Output to converters 14fl and 14fr.

Further, the DSP 13 uses the coefficient data Aj to Ej (i = 1 to 6) in parallel with the equalizing arithmetic processing of the L channel to perform the arithmetic operations shown in FIGS. 3 and 4 on the R channel audio signal Sr. The rear L channel audio signal Srl ′ and the rear R channel audio signal Srr ′.
The data is output to the DA converters 14rl and 14rr (step 105).

As described above, the sound quality control according to the selected mode and the equalizing curve is performed. Therefore, the user can select a desired mode and appropriately create sounds in the 12 bands common to the front and rear, or to create sounds in the 6 bands each independent to the front and rear.

<Advantages of the Invention> According to the present invention, the same equalizing curve is set on the front side and the rear side in a state where the number of bands is increased according to the preference of the user, or the number of bands is halved but the front side is set. And you can enjoy making sounds by setting equalizing curves independently on the rear side.

Further, according to the present invention, the hardware is not increased and only the arithmetic processing of the DSP is changed according to the selected mode.
It is possible to enjoy the two equalizing modes, which is advantageous in terms of cost, and the size of the device does not increase.

[Brief description of drawings]

FIG. 1 is a block diagram of a frequency characteristic control device according to the present invention, FIG. 2 is a display example in first and second modes, FIGS. 3 and 4 are signal flow diagrams of equalizing processing of DSP, and FIG. 3 is a flow chart of processing of the present invention. 13 …… Digital signal processor 16 …… Microcomputer 17a …… Operating section 17b …… Display section IMS …… Mode selection switch BSi …… Characteristic setting switch

Claims (1)

(57) [Claims] 1. A plurality of characteristic setting switches for setting an equalizing curve, a first mode in which all the characteristic setting switches are used for equalizing curve setting common to the front side and the rear side, and a half characteristic setting switch for the front side. The mode selection switch for selecting the second mode for setting the equalizing curve and the rest for the equalizing curve on the rear side and the equalizing curve common to the front side and the rear side set in the first mode are displayed. In the 2 modes, a display section for displaying the front side equalizing curve and the rear side equalizing curve respectively, the coefficient data according to the first mode and the coefficient data according to the second mode are stored, and the currently selected mode is stored. Coefficient data and the characteristic setting switch A controller for outputting the gain for each band are, on the digital audio data of L and R channels, performs a predetermined equalizing process using the gain of the input coefficient data and each band, front L
A frequency characteristic control device equipped with a digital signal processor that outputs audio signals of channels, front R channels, rear L channels, and rear R channels.