JPH10284964A - Sound volume adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain highly clear receiving under a situation where volume-up is not permitted at night by setting the standard value of a sound input signal level, decreasing or increasing gain by means of corresponding followup speed when the voice input signal level is larger or smaller than the standard value and non-linearly controlling an output signal level to be a fixed value. SOLUTION: A sound signal to a sound signal input terminal IN reaches a level detecting circuit LVD through a loudness correcting amplifier AP1 and a band-pass filter BPF, and detects the input sound signal level to control amplification characteristics to frequency in an amplifier AP1. It is controlled so as to obtain uniform amplification t the time of a high input sound level and to increase an amplification degree in a low frequency area, thereby correcting loudness, and adding the correction value to the amplifier AP2 for gain control. Amplifier AP2 gain is controlled by the output of a non-linear correcting circuit NLC so as to execute non-liner amplification. The sound signal of the input terminal IN is loudness-corrected in the amplifier AP1, non- linear amplification corresponding to a signal level is executed in the amplifier AP2 and transmission is executed to the output terminal OUT.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a volume control device for controlling the output level of an audio input signal so that it does not fluctuate greatly even if the level of the input signal changes. The sound volume control device of the present invention is incorporated in the sleep sound mode of a television or radio to enable reception with high clarity in a situation where the sound volume cannot be raised to a certain level at night, and in a noisy environment. It can be used for the audio equipment used.

[0002]

2. Description of the Related Art An audio circuit of a general television or radio audio device is designed to accurately amplify an input audio signal. For this reason, when the level of the audio signal is high, a loud sound is reproduced, and when the level is low, a low sound is output.

[0003] Such characteristics are desirable for televisions and radios used in ordinary environments since they faithfully reproduce input signals. However, such an audio device is not suitable for use at home in a situation where the volume cannot be raised to a certain level or higher at night or in a noisy environment. That is, in a general home, it is troublesome for surrounding people to output a sound of a certain level or higher at night. Also, when a low-level audio signal is received in a place with much noise, it is difficult to perform reception with high clarity due to the influence of noise.

Conventionally, as a method of compressing an output signal according to the state of an input signal, there is a dynamic range compression device. However, in this device, if the input can be performed, the output level ratio is linearly compressed to 1: 2, or a threshold hold level is set, and linear compression is performed at this level. The purpose was also used for noise reduction.

[0005]

According to the present invention, a standard value of the level of an audio input signal is set, and when the level of the audio input signal is larger than the standard value, the gain is appropriately set according to the level of the audio input signal. If the level of the audio input signal is smaller than the standard value, the gain is increased at an appropriate tracking speed according to the level of the audio input signal, and the level of the output signal is adjusted to the level of the audio input signal. However, the present invention has realized a sound volume control device that performs non-linear control so as to have a substantially constant value.

For this reason, the volume control device of the present invention can be used even in a situation where the volume cannot be raised to a certain level at night, and can receive a signal with high clarity even in audio equipment used in a noisy environment. Thus, an apparatus suitable for use in a night sound mode of a television or a radio is realized.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is an explanatory diagram showing an example of use of a volume control device of the present invention. In FIG. 1, IN is an audio signal input terminal, and PAN is a preamplifier for amplifying the audio signal. VCN is a volume control device of the present invention, and CON is a controller for controlling the intermittent operation of the function of the volume control device. PW
A is a power amplifier that amplifies an audio signal, and SP is a speaker that outputs audio.

The audio signal input terminal IN is connected to a preamplifier PA
N, and the output terminal of the preamplifier PAN is connected to the input terminal of the volume control device VCN. The output terminal of the volume control device VCN is connected to the input terminal of the power amplifier PWA, and the output terminal of the power amplifier PWA is connected to the speaker SP. The intermittent control of the function of the volume control device VCN is controlled by the controller CON.

The operation of the device having such a configuration will be described below. Preamplifier PAN and power amplifier PW
A has a linear amplification characteristic as shown in FIG. The linear amplification characteristic shown in FIG. 2A is a characteristic of a normal amplifier. The volume control device VCN of the present invention is set to have a non-linear amplification characteristic as shown in FIG. Volume control device VC

In N, first, when the input level is 100% (standard value), the output level is set to be the same level as the input (gain 0 dB). Input level or 1
Where the value exceeds 00% (standard value), the gain is reduced at an appropriate following speed in accordance with the level of the input signal so that the output level is kept constant. When the input level is smaller than 100% (standard value), the gain is increased as the level of the input signal is smaller, so that the level of the output signal is adjusted so as not to be too small.

When the input level is smaller (close to zero), a soft mute is applied so that the gain does not become too harsh due to excessive gain. As shown in FIG. 2B, when 100% = 0 db, -40 db
In the example where the gain is increased by A = 12 db at the input level of, the output at that time is −40 + 12 = −28
db, the compression characteristics are 10: 7.

Since the function of the volume control device VCN is controlled to be intermittent by the controller CON, the controller CO
When the function of the volume control device VCN is interrupted by N, the output signal of the preamplifier PAN is applied to the power amplifier PWA at the same level, amplified and amplified by the speaker SP.
Is converted to voice. The sound in this case has a magnitude proportional to the level of the input signal, and operates as a normal sound amplifier. When the function of the volume control device VCN is turned on by the controller CON and operated, the level of the output signal of the preamplifier PAN becomes 100%
In the case of (standard value), the output level of the volume controller VCN becomes the same level as the input (gain 0 dB), and the output signal of the preamplifier PAN is transmitted to the power amplifier PWA as it is.

The level of the output signal of the preamplifier PAN is 1
Where it exceeds 00% (standard value), the volume control device VCN
The output level is transmitted to the power amplifier PWA such that the output level becomes constant by reducing the gain in accordance with the level of the input signal at an appropriate following speed. When the level of the output signal of the preamplifier PAN is as small as 100% (standard value) or less, the gain is increased as the level of the input signal is reduced, and the output level is adjusted so that the output level is not too small, and transmitted to the power amplifier PWA. .

When the level of the output signal of the preamplifier PAN is even smaller (close to zero), the signal is transmitted to the power amplifier PWA with soft mute so that the gain is too high and the noise is not annoying. As a result, the function of the volume control device VCN is turned on by the controller CON.
The characteristics of the device when operated in the state shown in FIG. 3A are as follows. When the signal input level is 100% (set value) and the gain is 0 db or more, a limit function according to the signal level is provided. Even if the signal of the sound of the working input becomes loud, the sound of the output is kept almost constant.

[0015] For this reason, even when the level of the audio signal suddenly increases due to, for example, commercials, the audio output from the speaker is kept unchanged, so that there is no trouble even in a quiet place at night. Also, even in normal use, no discomfort due to a sudden increase in voice is generated. If the input level of the audio signal is 10
0% (set value), gain -40db below 0db
From the above to 0 db, the maximum Adb (for example,
The gain is increased by A = 12 db), and the loudness correction (or low boost) is applied in this range.

When the input level of the audio signal is equal to or lower than -40 db, the gain of the circuit drops rapidly, so that the audio level drops sharply. For this reason, when there is no audio signal, it is prevented that an unnecessary input signal such as noise is amplified by an amplifier circuit having an increased gain to generate noise. FIG. 3B shows the effect of the level of the input signal on the frequency characteristics of the volume control device VCN of the present invention and the effect (the characteristics of the loudness correction circuit).

Human hearing has a characteristic (loudness characteristic) that makes it difficult to hear high and low sound portions (particularly, low sound portions) at low volume. Volume control device VCN of the present invention
In order to perform natural reproduction of sound, boosting (enhancement) is performed to raise a sound in a low frequency region, for example, a portion of 50 to 150 Hz at low volume, but this boosting (enhancement) is performed by a normal device. In some cases, the amount of boost is changed depending on the position of the volume for setting the volume.

As described above, the volume control device VCN of the present invention
In, since the sound level of the input signal, that is, the volume of the input itself, is controlled, it is possible to enhance the bass that matches the characteristics of the human ear, so even small sounds can be masked. It is possible to perform reproduction with a sense of volume that is difficult to hear.

FIG. 4 is a connection diagram showing a specific configuration of the volume control device VCN of the present invention. In FIG. 4, IN is an audio signal input terminal, and OUT is an audio signal output terminal. AP1 is an amplifier for loudness correction, and AP2 is an amplifier for gain control. A BPS bandpass filter, LVD is a level detector, and NLC is a non-linear correction circuit.

The input terminal IN of the audio signal is connected to the input terminal of the amplifier AP1 for loudness correction and the band-pass filter BP.
Connected to S. Amplifier AP1 for loudness correction
Is connected to the input terminal of the gain control amplifier AP2, and the gain control amplifier AP2
The second output terminal is connected to the audio signal output terminal OUT.

The output terminal of the band-pass filter BPS is connected to the input terminal of the level detector LVD, and the output terminal of the level detector LVD is connected to the nonlinear correction circuit NLC. The output terminal of the level detector LVD is connected to the control signal input terminal of the amplifier AP1 for loudness correction, and the output terminal of the nonlinear correction circuit NLC is connected to the control signal input terminal of the amplifier AP2 for gain control.

The volume control device VCN thus configured
The operation will be described as follows. The audio signal applied to the input terminal IN of the audio signal is applied to the input terminal of an amplifier AP1 for loudness correction, and also applied to a band-pass filter BPS to remove frequency components other than the frequency component of the audio signal, thereby obtaining a level detector. Added to LVD. The level detector LVD detects the level of the input audio signal, and controls the amplification characteristic with respect to the frequency of the amplifier AP1 as shown in FIG.

That is, when the level of the input audio signal is a large level such as 1 or 2, control is performed so that amplification is substantially uniform for each frequency, and the level of the input audio signal is adjusted. As the level becomes lower as in 3, 4, and 5, control is performed so as to increase the amplification in the low frequency region more. The method of increasing the amplification degree in the low frequency region is controlled so that the loudness set to increase as the level of the input audio signal becomes lower is corrected. The output signal of the amplifier AP1 whose loudness has been corrected is applied to the amplifier AP2.

The gain of the amplifier AP2 is determined by the nonlinear correction circuit N.
It is controlled by the output signal of the LC, and its non-linear characteristic is set as shown in FIG. 3A in accordance with the level of the input signal. Is a non-linear amplification characteristic as shown in FIG. Therefore, the audio signal input terminal I
The audio signal added to the N is subjected to a loudness correction by an amplifier AP1, and a non-linear amplification according to a signal level is performed by an amplifier AP2 and sent to an output terminal OUT.

Therefore, by using this circuit,
If the level of the audio input signal is higher than the standard value, the gain is reduced according to the level of the audio input signal, and if the level of the audio input signal is lower than the standard value, the gain is reduced according to the level of the audio input signal. Thus, the level of the output signal can be controlled to be substantially constant irrespective of the level of the audio input signal by increasing the level at an appropriate following speed.

[0026]

As is apparent from the above description, according to the present invention, the standard value of the level of the audio input signal is set, and when the level of the audio input signal is larger than the standard value, the gain is set to the audio input signal. If the level of the audio input signal is smaller than the standard value, the gain is increased at an appropriate tracking speed according to the level of the audio input signal, and the level of the output signal is increased. Can be realized in a non-linear manner so as to be substantially constant regardless of the level of the audio input signal.

For this reason, the apparatus to which the present invention is applied can be used even in a situation where the volume cannot be raised to a certain level at night, and the clarity is high even when the audio equipment is used in a noisy environment. Reception becomes possible. In particular, when the apparatus of the present invention is used by being incorporated in a sleep sound mode of a television or a radio, the effect is great.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of use of a volume control device of the present invention.

FIG. 2 is a diagram for explaining a non-linear amplification characteristic of the volume control device of the present invention.

FIG. 3 shows the influence of the level of an input signal on the frequency characteristics of the volume control device of the present invention and the effect thereof.

FIG. 4 is a connection diagram showing a specific configuration of a volume control device VCN of the present invention.

[Explanation of symbols]

PAN: Preamplifier, VCN: Volume control device, PWA: Power amplifier, CON:
Controller, SP ... Speaker, IN ...
・ Audio signal input terminal, OUT ・ ・ ・ Audio signal output terminal,
AP1 ... Loudness correction amplifier, AP2 ...
・ Amplifier for gain control, BPF ...
Band pass filter, LVD: Level detection circuit, NLC: Non-linear correction circuit,

Claims (8)

[Claims] 1. A standard value of a level of an audio input signal is set,
If the level of the audio input signal is higher than the standard value, the gain is reduced according to the level of the audio input signal, and if the level of the audio input signal is lower than the standard value, the gain is reduced according to the level of the audio input signal. And a volume control device for controlling the level of the output signal to be substantially constant regardless of the level of the audio input signal. 2. A standard value of a level of an audio input signal is set,
If the level of the audio input signal is larger than the standard value, the gain is reduced at an appropriate tracking speed according to the level of the audio input signal, and if the level of the audio input signal is smaller than the standard value, the gain is reduced. A volume control device which increases the level of an output signal to a substantially constant value irrespective of the level of an audio input signal by non-linearly increasing according to the level of the signal. 3. A standard value of a level of an audio input signal is set,
When the level of the audio input signal is higher than the standard value, the gain is reduced at an appropriate tracking speed according to the level of the audio input signal, and when the level of the audio input signal is lower than the standard value, the gain is reduced. A volume control device for giving a loudness effect having a non-linear characteristic to an output signal, the amplification degree being increased in accordance with the level of an input signal. 4. A standard value of an audio input signal level is set,
If the level of the audio input signal is larger than the standard value, the gain is reduced at an appropriate tracking speed according to the level of the audio input signal, and if the level of the audio input signal is smaller than the standard value, the gain is reduced. In accordance with the signal level, the output signal level is increased at an appropriate following speed, and the output signal level is nonlinearly controlled so as to be almost constant regardless of the audio input signal level. A volume control device that reduces the level of the output signal. 5. A standard value of a level of an audio input signal is set,
If the level of the audio input signal is larger than the standard value, the gain is reduced at an appropriate tracking speed according to the level of the audio input signal, and if the level of the audio input signal is smaller than the standard value, the gain is reduced. A television volume control circuit for increasing the output signal level at an appropriate following speed in accordance with the signal level so as to nonlinearly control the output signal level so as to be substantially constant regardless of the level of the audio input signal; A volume control device that is incorporated in audio equipment such as radios and radios so that its functions can be intermittently controlled by a control circuit. 6. A standard value of a level of an audio input signal is set,
If the level of the audio input signal is larger than the standard value, the gain is reduced at an appropriate tracking speed according to the level of the audio input signal, and if the level of the audio input signal is smaller than the standard value, the gain is reduced. A television volume control circuit for increasing the output signal level at an appropriate following speed in accordance with the signal level so as to nonlinearly control the output signal level so as to be substantially constant regardless of the level of the audio input signal; A volume control device that is embedded in audio equipment such as a radio and a radio, and interlocks with the sleep function of the audio equipment so that the function is intermittent. 7. A standard value of a level of an audio input signal is set,
When the level of the audio input signal is higher than the standard value, the gain is reduced at an appropriate tracking speed according to the level of the audio input signal, and when the level of the audio input signal is lower than the standard value, the gain is reduced. A volume control circuit that applies a non-linear characteristic loudness effect to the output signal so that the amplification degree is increased according to the level of the input signal, and reduces the level of the output signal when there is no input signal. Is a volume control device that is built into audio equipment such as televisions and radios, and interlocks with the sleep function of audio equipment to intermittently intermittently operate the sleep function. 8. A standard value of a level of an audio input signal is set,
If the level of the audio input signal is larger than the standard value, the gain is reduced at an appropriate tracking speed according to the level of the audio input signal, and if the level of the audio input signal is smaller than the standard value, the gain is reduced. In accordance with the signal level, the output signal level is increased nonlinearly so as to be almost constant regardless of the level of the audio input signal by increasing at an appropriate following speed, and when there is no input signal, A volume control device that incorporates a volume control circuit for reducing the level of an output signal into audio equipment such as a television or a radio, and interlocks the function with the sleep function of the audio equipment.