JPH0590858A - Variable characteristic device - Google Patents

Abstract

PURPOSE:To provide a circuit that can automatically and adaptively control frequency characteristics to be the optimum state in response to the property of the input signal. CONSTITUTION:In a device for supplying a control signal for characteristic control to a variable filter 108 that can very characteristics of an input signal and outputs, a low pass filter 103 detects the low frequency component of the input signal. A detector 104, counter 105, a sample hold circuit 106, and a D/A converter 107 detect sound number information and sound volume information from the low frequency component, inputs them in a synthesizer 111, and the frequency characteristics of the variable filter 103 is controlled by the output of the synthesizer 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a characteristic variable device that automatically obtains output characteristics optimized according to the characteristics of an input signal without requiring user adjustment.

[0002]

2. Description of the Related Art FIG. 7 shows a variable filter 2 for adjusting sound quality in an audio device. The audio signal (input signal) supplied to the input terminal 1 is output to the output terminal 4 after the frequency characteristic is limited (the sound quality is controlled) in the variable filter 2. The frequency characteristic control signal for the variable filter 2 is input from the terminal 3, which is a signal generated by the user's operation.

The setting of the sound quality has been conventionally determined by the user, and it is sufficient that the device can change the sound quality according to the user's control. Since this method and the filter characteristic set by the user are maintained as they are, it is convenient when the same kind of music as that used for the sound quality adjustment is used as the source. However, there are various kinds of music used as a source by the user. In some cases, it may be better to adjust the sound quality (filter characteristic) even for the same music.

For example, in the case of music that includes delicate and bold musical tones such as classical music, the user can enjoy a powerful sound quality that emphasizes the low range in a certain period, emphasizes the mid range to the high range in a different period, and plays a wind instrument. There are times when you want to watch with close-up sound quality. However, the current method requires manual control of the sound quality in one song, which is practically impossible. When listening to music like classical music and then listening to intense music such as rock, which is completely different from the sound quality of classical music, the control of the sound quality must be changed frequently, which is very annoying.

[0005]

According to the conventional control method, even if the tune changes during the song being viewed, it cannot be immediately changed to the optimized sound quality, and the genre is completely different. If you try to listen to the music, you often have to manually adjust the control state. Therefore, an object of the present invention is to provide a characteristic varying device capable of adaptively automatically controlling the frequency characteristic to an optimized state according to the characteristics of the input signal.

[0006]

According to the present invention, a property detecting means for detecting a specific frequency component of an input signal and a detection output of the property detecting means are provided in the signal path of the input signal. And a control means for variably controlling the characteristics of the filter.

[0007]

By the above means, the filter characteristic is automatically controlled to the optimum characteristic for the characteristic of the input signal.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. A signal whose source is a music program is input to the input terminal 101. The input terminal 101 is connected to the variable filter 108 and the low pass filter 103. The low-frequency component extracted by the low-pass filter 103 is input to the detector 104. The detector 104 generates a signal so that the loudness of the sound and the number of sounds per unit time can be detected. The generated signal is detected by the counter 105 for the number of sounds per unit time, and the sample hold (S / H) circuit 106 for the sound volume. Therefore, the count clock from the terminal 109 is input to the counter 105, and the terminal 1 is input to the sample hold circuit 106.
The sampling clock from 10 is input.

The count value (sound number) of the counter 105 is input to a digital / analog (D / A) converter 107, converted into an analog signal, and input to a synthesizer 111. The sample signal from the sample hold circuit 106 is also input to the synthesizer 111. The signal combined by the combiner 111 is supplied to the control terminal of the variable filter 108 as a frequency characteristic control signal.

Next, description will be given with reference to a waveform diagram. Figure 2 (A)
Shows a signal of a certain music for several seconds, and the portion where the frequency is low and the amplitude is large is where the bass drum of the drum is struck. The other part is where other instruments or drum cymbals are struck. FIG. 6B shows an output waveform of the low-pass filter 103, in which the amplitude of components other than the low-pitched sound is small.

FIG. 3A shows a detector 104 and a counter 1.
05, D / A converter 107, sample and hold circuit 10
6 shows a specific configuration example of No. 6. Low pass filter 10
The low frequency component from 3 is the input terminal 201 and the capacitor 20.
2 is supplied to one end of the resistor 203, the anode of the diode 204, and one input terminal of the comparator 205.
The DC voltage source 20 is connected to the other input terminal of the comparator 205.
The DC voltage from 6, 207 is supplied. The cathode of the diode 204 is connected to one end of the resistor 208, one end of the capacitor 209, and the output terminal 210. The other end of the resistor 208 is turned on and off by a switch, and its drive clock is supplied from the above terminal 110. The other end of the capacitor 209 is grounded.

Since the comparator 205 compares the input with a predetermined level, the peak portion of the waveform shown in FIG. 2B is detected (the number of sounds). This sound number signal is pulse-like and appears at, for example, substantially constant intervals, and can be monitored, for example, by a display or the like through the output terminal 211.
The output of the comparator 205 is further input to the counter 105. This counter 105 obtains the sound number data per unit time. The sound number data is converted into an analog signal by the digital-analog converter 107 and is output to the output terminal 213.

FIGS. 3B and 3C show an example of the synthesizer 111 to which the volume detection output and the sound number detection output are supplied. The combiner 111 determines what frequency band is emphasized or weakened when what kind of signal is input. Therefore, a plurality of synthesizing circuits having different input / output characteristics are prepared in parallel, and the output of each synthesizing circuit is supplied to the characteristic control terminal of the corresponding filter section. This determines the overall characteristics of the variable filter 108 as a whole. The synthesizer 111 shown in FIG. 7B is composed of transistors Q1 and Q2, and the bases of the transistors are set as input terminals 31 and 32 for receiving the detection outputs. The emitters of the transistors Q1 and Q2 are grounded via resistors, and the collectors of the transistors Q1 and Q2 are commonly connected and then connected to the power supply line. Then, a combined output is obtained from the common connection portion of the collectors of the respective transistors and is led to the output terminal 33.

The composition of the combiner 111 may be as shown in FIG. Each detection output is input terminal 3
1, 32 are input. Each input is input to the positive input terminal of the operational amplifier DA via a resistor. The negative input terminal of the operational amplifier DA is grounded. A feedback resistor is provided between the positive input terminal and the output terminal of the operational amplifier DA. At the output terminal 33 of the operational amplifier DA,
It is possible to obtain an output proportional to the combination of the detection outputs.

FIG. 3D shows a concrete configuration example of the variable filter 180. In the figure, the output (control signal) from the combiner 111 is supplied to the input terminal 41. Terminal 41
Is connected to the base of the transistor 47 via the diode 42, the capacitor 43, and the diode 46. The base of this transistor 47 is a diode 44, a resistor 4
It is connected to the power supply line via 5 and is grounded via the current source 48 having a control terminal. The collector of the transistor 47 is connected to the power supply line, and the emitter is grounded via the resistor 49 and the current source 50 having a control terminal. The connection point between the resistor 48 and the current source 50 is
The capacitor 51 is grounded and is connected to the output terminal 52.

The variable filter 108 includes a current source 48,
The characteristics can be changed by supplying the output of the combiner 108 to the control terminal of 50 and controlling the current. Therefore, the combiner 111 determines which frequency band should be emphasized or weakened when what kind of signal is input, and in response to this, the variable filter 10 is determined.
8 realizes the change of the band characteristic.
When the current of the current source 48 is changed, the high frequency band characteristic is changed, and when the current of the current source 50 is changed, the low frequency band characteristic is changed. Actually, if the cutoff frequencies of the high-pass filter and the low-pass filter are different,
As many types as the number of outputs from the combiner 111 are prepared and finer control is performed.

FIG. 4 shows another embodiment of the present invention. Although the previous embodiment has been described based on analog signal processing, this embodiment incorporates elements of digital signal processing. The parts corresponding to the block functions shown in the embodiment of FIG. Input terminal 10
The input signal input to 1 is a low-pass filter (LP
F) 103 and the variable filter 108. The low-pass frequency component derived from the low-pass filter 103 is input to the detector 104 and detected, and the number-of-sounds information is input to the counter 105 and is obtained by counting based on the clock from the terminal 109. .. Further, the volume information is sampled and held by the sample hold (S / H) circuit 106 based on the clock supplied from the terminal 110, and the value is converted into digital data by the analog-digital (A / D) converter 122. To be detected. The quantization clock is supplied from the terminal 121. The outputs of the counter 105 and the analog-digital converter 122 are input as address information of the read only memory (ROM) 123. The ROM 123 stores data of factors that determine what frequency characteristic is to be obtained as an output signal according to the content when the number of sounds and the volume information are received.
The output data of the ROM 123 is digital analog (D /
A) It is converted into an analog signal by the converter 124 and is supplied to the control terminal of the variable filter 108. Thus, at the output terminal 102, it is possible to obtain a signal in which the characteristics of the input signal are automatically adjusted.

FIG. 5 shows another embodiment of the present invention. The basic configuration is the same as that of the embodiment shown in FIG. 4, but is different in that a plurality of means for acquiring the sound number information and the volume information are provided in parallel. In the embodiment of FIG. 4, when the sound number information and the volume information are acquired, they are acquired through the low pass filter (LPF) 103, but in this embodiment, the low pass filter 10 is used.
3A, the band pass filter (BPF) 103B, and the high pass filter (HPF) 103C are used to acquire the sound number information and the sound volume information in each band. Therefore, in order to obtain the tone number information and the volume information in each band, the block number has a suffix A,
B and C are added for identification. The sound number and volume information of each band is used for reading data from the ROM 23, and the data output from the ROM 123 is converted into an analog signal by the digital-analog converter 124 and supplied to the control terminal of the variable filter 108.

FIG. 6A shows another embodiment of the present invention. This embodiment is adapted to realize variable frequency characteristics when the input signal is a PCM signal. An input signal from the input terminal 131 is input to a random access memory (RAM) 133 that rearranges data, and the RAM 140 used as a delay element.
Entered in. The clock from the terminal 132 is used in the RAM 133. By rearranging the data, the frequency component can be identified, and the output of the RAM 133 is input to the low pass filter (LPF) 134.
The low frequency components extracted by the low pass filter 134 are input to the data converter 135. Data converter 1
At 35, the number of sounds and the volume of the signal detected by the low-pass filter 134 are converted into a signal having contents that can be identified by the ROM 136. As a result, the digital variable filter 14 is read from the ROM 136 according to the number of sounds and the volume of the input signal.
It is possible to obtain control data for varying the frequency characteristic of No. 2 and obtain a PCM signal whose characteristic is controlled at the output terminal 143.

FIG. 6 (B) shows the output characteristics when the variable filter 142 is controlled. Each case is the case of the following (1) to (4), and the corresponding curves are also attached to the characteristic curves of FIG. (1) The number of notes is small,
When the volume is low, (2) the number of notes is small but the volume is high, (3) when the number of notes is high but the volume is low, (4) when the number of notes is high and the volume is high.

As a result, the sound quality can be automatically changed in accordance with the input signal, and the optimized sound quality can be obtained regardless of what music source is watched without the need for manual control.

[0023]

As described above, according to the present invention,
Frequency characteristics can be adaptively automatically controlled to an optimized state according to the characteristics of the input signal.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of an input signal waveform supplied to an input terminal of the circuit of FIG.

FIG. 3 is a diagram showing a specific circuit example of each block in FIG.

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

FIG. 5 is a diagram showing still another embodiment of the present invention.

6A and 6B are diagrams showing yet another embodiment of the present invention, in which FIG. 6A is a block diagram and FIG. 6B is a diagram showing an output characteristic example thereof.

FIG. 7 is a diagram showing an example of a conventional sound quality adjustment circuit.

[Explanation of symbols]

103 ... Low-pass filter (LPF), 104 ... Detector, 105 ... Counter, 106 ... Sample hold circuit, 107,122 ... Analog digital (A / D) converter, 108 ... Variable filter, 111 ... Synthesizer, 124 …
Digital-analog (D / A) converter.

Claims (2)

[Claims] 1. A device for supplying a control signal for controlling a characteristic to a variable filter capable of varying and outputting a characteristic of an input signal, wherein the detecting means detects at least one frequency component of the input signal, The detection output of the detection means is input, and means for determining the content of the control signal for realizing a preset output frequency characteristic according to the detection output, and the variable filter according to the input signal. A characteristic variable device characterized in that the characteristic is automatically variable. 2. The characteristic variable device according to claim 1, wherein the detection means includes means for detecting sound number information and volume information of the input signal.