JPH04298200A - Automatic sound volume adjustment device in surround circuit - Google Patents

Abstract

PURPOSE:To adjust automatically a change in a sound volume due to a change in the signal content in the surround circuit having a matrix circuit. CONSTITUTION:The device is provided with a detection integration circuit 5 in which an increase/decrease in a difference signal (R-L) between a left audio signal L and a right audio signal R obtained from a matrix circuit 1 is detected and a detection control signal (d) is outputted. The detection control signal (d) from the detection integration circuit 5 is inputted to a mixing circuit 6 together with a main sound volume control signal (m) from a main sound volume adjustment device 4. The mixing circuit 6 mixes the detected control signal (d) and the main sound volume control signal (m) to generate a sound volume control signal (c), which is inputted to a sound volume adjustment attenuator circuit 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic volume adjustment device for a surround circuit used in electronic and audio equipment such as television receivers and stereo audio equipment.

0002

2. Description of the Related Art A conventionally used general matrix surround circuit will be explained with reference to FIG. In Figure 2, 1 is a matrix circuit, 2 is a delay circuit (or phase shift circuit), 3 is a volume adjustment attenuator circuit, 4 is a main volume adjuster, 7 and 8 are adders, and 9, 10, and 11 are output amplifiers. 9 is the front left audio output amplifier, 10 is the front right audio output amplifier, 11 is the rear audio output amplifier,
Reference numerals 12, 13, and 14 are speakers, and 12 is a front left audio speaker, 13 is a front right audio speaker, and 14 is a rear audio speaker.

A two-channel stereo left audio signal L and right audio signal R are input to a matrix circuit 1, from which a difference signal (LR) is extracted. Then, in a delay circuit (or phase shift circuit) 2, the difference signal (LR) output from the matrix circuit 1 is subjected to delay processing or phase shift processing to obtain a surround signal S. Next, this surround signal S is added to the left audio signal L and right audio signal R of the original signal. That is, the surround signal S is added to the left audio signal L by the adder 7, and the adder 8
is added to the right audio signal R to obtain a signal (L+S) and a signal (R+S). Furthermore, when the surround signal S is output from the rear audio speaker 14, the surround signal S is used as is.

(L+S), (obtained as described above)
R+S), S audio signals are respectively input to the volume adjustment attenuator circuit 3, and the volume adjustment attenuator circuit 3
Each audio signal is outputted from speakers 12, 13, 14 via output amplifiers 9, 10, 11. In other words,
The audio signal (L+S) is output from the front left audio speaker 12 through the front left audio output amplifier 9,
The audio signal (R+S) is output from the front right audio output amplifier 10.
The surround signal S is output from the front right audio speaker 13 through the rear audio output amplifier 11, and the surround signal S is output from the rear audio speaker 14 through the rear audio output amplifier 11. User(
(not shown), depending on the input source, each speaker 12,
13 and 14. Adjust the main volume adjuster 4 to obtain the results from 13 and 14.

[0005]

[Problems to be Solved by the Invention] However, in the conventional surround circuit of this type configured as described above, two
Channel stereo left audio signal L and right audio signal R
are respectively input to the matrix circuit 1 and a difference signal (L-R) is obtained by this matrix circuit 1. Therefore, this difference signal (L-R) is a monaural audio signal, that is, a left audio signal L and a right audio signal R. If L=R, or if the left audio signal L and right audio signal R are stereo audio signals, L=R.
If the signal has the following relationship, it will not be output. Furthermore, if there is a level difference or a phase difference between the left audio signal L and the right audio signal R, an output corresponding to the difference between these audio signals will be obtained.In other words, depending on the content of the audio signal, The level of the differential signal (LR) will increase or decrease.

For this reason, for an input source that constantly switches between a monaural audio signal and a stereo audio signal, such as television broadcasting, for example, no surround signal is output when the monaural audio signal is output, and when the stereo audio signal is output, the left audio signal is output. The level of the surround signal changes due to the separation between the L and right audio signals R, and the user adjusts the volume with the main volume adjuster each time.
The drawback was that you had to make adjustments to get the volume to your liking.

[0007]

[Means for Solving the Problems] In order to eliminate the drawbacks of the conventional techniques as described above, the present invention
a detection/integration circuit that detects an increase/decrease in the level of and outputs a detection control signal, and a mixing circuit that mixes the detection control signal output from the detection/integration circuit and the main volume control signal from the main volume adjuster. establish.

[0008]

[Operation] Difference signal obtained from the matrix circuit (L-R
), the differential signal (LR) component is detected in the detection/integration circuit to obtain a detection control signal which is a DC voltage. This detection control signal is input to the mixing circuit together with the main volume control signal, which is a DC voltage from the main volume adjuster. The detection control signal and the main volume control signal are mixed in this mixing circuit to obtain a volume control signal which is a DC voltage, and this volume control signal is input to a volume adjustment attenuator circuit and output from each speaker. The overall volume will be adjusted automatically.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic volume adjustment device in a surround circuit according to the present invention will be described below with reference to FIG. 1, and parts corresponding to those of the conventional example shown in FIG. 2 will be described with the same reference numerals. In FIG. 1, 1 is a matrix circuit, 2 is a delay circuit (or phase shift circuit), 3 is a volume adjustment attenuator circuit, and 4 is a main volume control signal m, which is a DC voltage, in response to an operation by a user (not shown). A main volume adjuster 5 outputs a difference signal (L) from the matrix circuit 1.
-R) A detection/integration circuit that includes an integration circuit that detects an increase or decrease in the level of the component and generates a DC voltage according to the level, and outputs the DC voltage as a detection control signal d; 6 is from the main volume adjuster 4; This is a mixing circuit that mixes the main volume control signal m of the main volume control signal m and the detection control signal d from the detection/integration circuit 5 and outputs the volume control signal c, which is a DC voltage. 7 and 8 are adders; 9, 10, and 11 are output amplifiers; 9 is an output amplifier for front left audio; 10 is an output amplifier for front right audio; 11 is an output amplifier for rear audio; 12, 13, 1
4 is a speaker, 12 is a front left audio speaker, 13 is a front right audio speaker, and 14 is a rear audio speaker.

The operation of the automatic volume adjustment device in the surround circuit of the present invention constructed as described above will be explained below. A two-channel stereo left audio signal L and right audio signal R enter a matrix circuit 1, from which a difference signal (LR) is taken out. This difference signal (LR) is subjected to delay processing or phase shift processing in a delay circuit (or phase shift circuit) 2, and is output as a surround signal S. The surround signal S is added to the left audio signal L in an adder 7 and added to the right audio signal R in an adder 8 to obtain a signal (L+S) and a signal (R+S). (L+S), (R+S) obtained as above
. That is, the audio signal (L+S) is amplified by the front left audio output amplifier 9 and output from the front left audio output speaker 12, and the audio signal (R+S) is amplified by the front right audio output amplifier 10 and output from the front left audio output speaker 12. Right audio speaker 13
is output from. In addition, the surround signal S is amplified by the rear audio output amplifier 11 and is amplified by the rear audio speaker 14.
is output as rear audio.

Difference signal (LR) from matrix circuit 1
) is also input to the detection/integration circuit 5. The detection/integration circuit 5 detects an increase/decrease in the difference signal (LR) component from the matrix circuit 1 and outputs a DC voltage corresponding to the detected level as a detection control signal d. On the other hand, a user (not shown) operates the main volume adjuster 4 to adjust the volume output from each speaker 12, 13, 14 to a desired volume level. The main volume controller 4 outputs a main volume control signal m, which is a DC voltage level according to a volume adjustment operation by a user (not shown).
is output. A detection control signal d which is a DC voltage from the detection/integration circuit 5 and the main volume adjuster 4
The main volume control signal m, which is a DC voltage from the main volume control signal m, is input to the mixing circuit 6. This mixing circuit 6
A volume control signal c is obtained at . This volume control signal c becomes a signal (m-A×d). Here, A is the control level by the detection control signal d with respect to the DC voltage of the main volume control signal m from the main volume adjuster 5. The volume control signal c=(m
-A.d) is input to the volume adjustment attenuator circuit 3, and is passed through the output amplifiers 9, 10, 11 to the speaker 12.
, 13, and 14 are automatically adjusted.

In the above embodiment, the detection/integration circuit 5
Although these have been described as being integrated, they may be configured to be separated into a front-stage detection circuit and a rear-stage integration circuit. In other words, the detection circuit is a differential signal (L
- When detecting the level of the R) component and connecting it to the next-stage integrating circuit, minimize the influence of the integrating circuit on the differential signal (L-R) input to the delay circuit (or phase shift circuit) 2. It is a circuit constructed for the purpose of the present invention, and it is possible to share the input resistance with an integrator (integration circuit). Therefore, in the above embodiment, the detection/integration circuit 5 is integrated, but the present invention The present invention is not limited to this, and may be composed of a detection circuit and an integration circuit.

[0013]

[Effects of the Invention] Since the automatic volume adjustment device for a surround circuit according to the present invention has the above-described configuration, it can receive an input source such as a television broadcast where monaural audio signals or stereo audio signals are constantly switched. Since the overall volume output from each speaker is automatically adjusted even when the signal content is changed, the user does not have to adjust the volume each time the volume changes due to changes in signal content. be able to.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic volume adjustment device in a surround circuit according to the present invention.

FIG. 2 is a block diagram showing an example of a conventional surround circuit.

[Explanation of symbols]

1 Matrix circuit 2 Delay circuit (phase shift circuit) 3 Volume adjustment attenuator circuit 4 Main volume adjuster 5 Detection/integration circuit 6 Mixing circuit 7, 8 Adder 9 Front left audio output amplifier 10 Front right audio output amplifier 11 Rear audio output amplifier 12 Front left audio speaker 13 Front right audio speaker 14 Rear audio speaker L Left audio signal R Right audio signal L-R differential signal S Surround signal d Detection control signal m Main volume control signal c Volume control signal

Claims (2)

[Claims] 1. A surround circuit having a matrix circuit into which two different audio signals are input, a difference signal between the two different audio signals obtained from the matrix circuit is input, and an increase or decrease in the level of the difference signal is detected. a detection/integration circuit that outputs a DC voltage according to the increase/decrease level of the sound; a main volume adjuster that is operated to adjust the main volume and outputs a DC voltage according to the operation; and a detection/integration circuit that outputs a DC voltage according to the operation. An automatic volume adjustment device in a surround circuit, comprising: a mixing circuit that mixes and outputs a DC voltage from the main volume controller and a DC voltage from the main volume controller. 2. The automatic volume adjustment device in a surround circuit according to claim 1, wherein the detection/integration circuit is comprised of a front-stage detection circuit and a rear-stage integration circuit.