JP3100415B2 - Volume control circuit of sound field control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound field control system for giving a sense of realism by adding information for giving a sound sound and a sense of expansion in a stereo reproducing apparatus.
In particular, the present invention relates to a sound volume control circuit of a sound field control device capable of reducing residual noise generated from a sound effect generation circuit even when the sound volume is reduced to a predetermined amount or less.

[0002]

2. Description of the Related Art With the development of so-called digital elements, audio information output from a signal source is digitally processed in real time, sound effects are generated, mixed with direct sound, and output from a speaker, thereby realizing stereo reproduction with a sense of realism. It is possible. In this case, it is common to use a digital signal processor (DSP) to generate a sound effect. The output of the signal source is converted from analog to digital to generate a sound effect by digital operation, and then to digital to analog conversion. It is directly mixed with the sound in the mixer.

FIG. 4 is a functional diagram of a conventionally used sound field control system, and an audio signal output from 201 is a main volume 202 for adjusting the overall volume.
After that, the path branches into two paths. One is input to the direct mixer 205 as a direct sound, and the other is input to the DSP 203 to generate a sound effect. DSP203
Includes peripheral circuits such as an analog / digital converter, a digital / analog converter, and a low-pass filter for demodulation. The sound effect generated by the DSP 203 is input to the mixer 205 via a sound effect volume 204 for adjusting the relative volume between the direct sound and the sound effect.

[0004] The output of the mixer 205 is power-amplified by a power amplifier (not shown) and output as a sound from a speaker (not shown). However, since the DSP 203 includes a digital-to-analog converter, residual noise is generated. In particular, when the main volume 202 is narrowed to a predetermined value or less, the residual noise becomes particularly annoying, and the Was giving discomfort.

To solve this problem, for example, a DSP
In the state where the noise level is relatively lowered by inserting a limiter circuit into the output of, or so-called muting is applied to the sound effect when the main volume is fully turned down, the noise is suppressed.

[0006]

However, even in this case, even if the main volume is less than a predetermined amount, the effect of noise suppression does not appear in the state just before the diaphragm is completely stopped, so-called S / N feeling. Deterioration cannot be avoided. In particular, in the case of muting, it is difficult to obtain a natural audibility because muting acts on and off.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides a sound volume control circuit of a sound field control device that suppresses residual noise without any uncomfortable feeling even when the main volume is reduced to a predetermined amount or less. The purpose is to provide.

[0008]

FIG. 1 is a basic configuration diagram of a sound volume control circuit of a sound field control device according to the present invention. The sound signal source 101 outputs a sound signal, and the sound signal source 101 outputs the sound signal. Signal attenuating means 102 for attenuating a predetermined amount of audio signal, a sound effect generating means 103 for generating a sound effect signal based on the sound signal attenuated by the audio signal attenuating means 102, and an output from the sound effect generating means 103. Sound signal attenuating means 104 for attenuating the sound effect signal by a predetermined amount.
A signal mixing means 105 for mixing the sound signal attenuated by the sound signal attenuating means 102 with the sound effect signal attenuated by the sound effect signal attenuating means 104; Audio signal attenuation detecting means 106; sound effect signal attenuation determining means 107 for determining the attenuation of sound effect signal attenuating means 104 based on the main audio signal attenuation detected by main audio signal attenuation detecting means 106; , Consisting of

[0009]

According to the sound volume control circuit of the sound field control device according to the present invention, the sound volume of the sound effect is set in accordance with the setting of the main volume, so that the residual noise of the sound effect generation circuit becomes relatively large. Is prevented.

[0010]

FIG. 2 is a circuit diagram of an embodiment of a sound volume control circuit of a sound field control device according to the present invention. An audio signal output from an audio signal source 201 which is, for example, a CD player is attenuated by a main volume 202. Is done. The amount of attenuation is determined by the rotation angle of the main volume 202. The rotation angle of the main volume 202 is the main volume 2
02 is detected by a potentiometer 206 directly connected to the rotation shaft 02.

The output of the main volume 202 is branched into two and one is directly connected to the first input terminal of the mixing amplifier 205. The other one is connected to the DSP 203 and is once converted to a digital signal and then digitally processed to generate a sound effect corresponding to the audio signal and output it as an analog signal.

The sound effect output from the DSP 203 is, for example, a sound effect volume 204 composed of an electronic volume.
Is input to The attenuation of the electronic volume can be set by a control voltage applied from the outside. This control voltage is given by an output voltage of a potentiometer 206 directly connected to the main volume 202.

That is, both ends of the potentiometer 206 are connected to a power supply of, for example, +5 V and a ground line, and the movable end is connected to a control terminal of the sound effect volume 204. The other end of the capacitor whose one terminal is grounded is connected to the movable end in order to absorb noise generated when the movable end moves. Therefore, a voltage proportional to the rotation angle of the main volume 202 is obtained at the movable end of the potentiometer 206.
04 is set.

The output of the sound effect volume 204 is connected to the second input terminal of the mixing amplifier 205 and mixed with the audio signal input to the first input terminal.
5 outputs a signal obtained by mixing the audio signal and the sound effect. FIG. 3A is a characteristic diagram of the main volume 202, in which the horizontal axis represents the rotation angle of the main volume and the vertical axis represents the attenuation rate of the audio signal.

Generally, in order to adjust the sound volume, a volume having a characteristic of greatly attenuating at a portion where the rotation angle is large and decreasing the attenuation rate at a portion where the rotation angle is small is often used for adjusting the volume. This characteristic is particularly specified. It is not something to be done. FIG. 3B is a characteristic diagram of the potentiometer 206. The horizontal axis represents the rotation angle of the main volume, and the vertical axis represents the output voltage of the movable end.

Generally, in a potentiometer, an output voltage proportional to the rotation angle is obtained. FIG. 3C is a characteristic diagram of the sound effect volume 204, in which the horizontal axis represents the control voltage,
The vertical axis indicates the attenuation rate. In the present invention, a filter having a characteristic that the attenuation rate is 0 dB when the voltage is equal to or higher than a predetermined control voltage and that the attenuation rate sharply increases when the voltage is equal to or lower than the predetermined control voltage is used.

When an electronic volume having such characteristics is used, when the main volume 202 is used in a predetermined amount or more, the sound effect is supplied to the mixing amplifier 205 without attenuation. On the other hand, when used below a predetermined amount, noise generated from the DSP is suppressed by rapidly attenuating the sound effect. At this time, the sound effect is attenuated, but the overall sound volume is also low, so the sound field control function is an area where the effect cannot be originally exhibited, and does not cause any particular inconvenience to general users.

The same effect can be obtained even if the main volume 202 is an electronic volume and the main volume 202 and the sound effect volume 204 are controlled by the output voltage of the potentiometer.

[0019]

According to the present invention, when the main volume is reduced to a predetermined value or less, the sound effect signal is reduced by the sound effect volume in accordance with the rotation angle of the main volume, and D is reduced.
The sound generated by the SP is prevented from becoming muddy.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a volume adjustment circuit of a sound field control device according to the present invention.

FIG. 2 is a circuit diagram of a first embodiment of a sound volume adjusting circuit of the sound field control device according to the present invention.

FIG. 3 is a characteristic diagram of a main volume, a potentiometer, and a sound effect volume.

FIG. 4 is a diagram showing one of volume control circuits of a conventional sound field control device.
It is a circuit diagram showing an example.

[Explanation of symbols]

 101 audio signal source 102 audio signal attenuating means 103 effect sound generating means 104 effect sound signal attenuating means 105 signal mixing means 106 audio signal attenuation detecting means 107 effect sound signal attenuation determining means

Claims (1)

(57) [Claims] An audio signal source (10) for outputting an audio signal.
1) an audio signal attenuating means (102) for attenuating the audio signal output from the audio signal source (101) by a predetermined amount;
Sound effect generating means (1) for generating a sound effect signal based on the sound signal attenuated by the sound signal attenuating means (102);
03) and the sound effect signal attenuating means (1) for attenuating the sound effect signal output from the sound effect generating means (103) by a predetermined amount.
04) and a signal mixing means (10) for mixing the sound signal attenuated by the sound signal attenuating means (102) and the sound effect signal attenuated by the sound effect signal attenuating means (104).
5) a main sound signal attenuation detecting means (106) for detecting an attenuation set amount of the sound signal attenuating means (102) in the sound volume control circuit of the sound field control device comprising: The sound effect signal attenuating means (10) based on the main audio signal attenuating amount detected by the amount detecting means (106).
4) The sound effect signal attenuation determining means (1) for determining the attenuation.
07), the sound volume control circuit of the sound field control device.