JPH0252000A - Sound conversion circuit for high definition tv - Google Patents

Abstract

PURPOSE:To utilize the speaker arrangement system of 4-channels by forming the sound output signal of 3-channels for a front side and 1-channel for a rear side even when a sound input is 2-channels. CONSTITUTION:When only 2-channels of the sound input are provided, each one is added by an adder 9, only a specific frequency component or lower is extracted from an LPF 11, impressed on a central speaker 25 and a sound signal (R-L) being subtracted by a subtracter 5 receives a phase conversion operation being a function (f) through a phase conversion circuit 6. The function f(R-L) is subtracted from the original signal R of a right sound signal, impressed on a right sound output circuit 15, the original signal L of a left sound signal and the function f(R-L) are added and impressed on a left sound output circuit 17. The sound output signal from the right and left sound output circuits 15 and 17 are impressed on right and left speakers 21 and 24 and impressed as a composition signal on rear speakers 22 and 23 being serially inserted into between respective plus-terminals. Thus, the maximum effect of the 4-channels speaker arrangement can be performed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a high-definition television system having a four-channel (left, right, center, rear) speaker arrangement, and a two-channel (left, right) audio signal. This invention relates to an audio conversion circuit for high-definition television that attempts to effectively utilize the four-channel speaker arrangement system in a case where only 4 channels are available.

(Conventional technology) As a high-definition television audio system.

In order to enhance the sense of presence through the synergistic effect of the large screen and detailed images, we have created three front channels (left,
A four-channel system called the 3-1 system has been proposed by NHK, with one channel in the rear (right, center) and one in the rear, and the speaker arrangement of high-definition televisions is basically compatible with the four-channel system.

On the other hand, as a high-definition television audio transmission format that takes satellite transmission into consideration, due to restrictions on the amount of transmitted information,
Bit 4 channel A mode.

Two transmission modes have been proposed: 11-bit 2-channel B mode, and the sound quality level of each is as follows.

14-bit PCM or more during 8-bit transmission (A mode),
It is equivalent to 16-bit PCM when transmitting 11 bits.

In the case of A mode 4 channels, the 4 channel speaker arrangement W (left, right) is shown in FIG.

Speakers 50, 51, 52 are each element of the center, rear)
53, 54, respectively, to the audio input terminals 41, 42, 43, 44 and the audio output circuit 45.
46°, 47, 48, and the effect of the 4-channel speaker arrangement can be maximized.

(Problem to be Solved by the Invention) However, in the case of B mode 2 channels, only the elements of 2 channels out of each element of the 4 channel speaker arrangement are used, and the effect of the 4 channel speaker arrangement is not fully realized. There was a problem of not being kept alive.

SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to provide a high-definition television audio conversion circuit that can effectively utilize a four-channel speaker arrangement system.

(Means for Solving the Problems) In order to solve the above-mentioned aIM, the present invention is a television system having a four-channel speaker arrangement consisting of left, right, center, and rear speakers, and in which the audio signal is transmitted from only two left and right channels. In the audio conversion circuit for high-definition television when the signal is not given, the phase of the central audio output signal extracted from only the low frequency components of the added left and right audio signals and the subtracted left and right audio signals is converted by a phase conversion circuit, It is configured to generate left and right audio output signals obtained by adding and subtracting left and right audio signals to the phase-converted signal, and a rear audio output signal consisting of a composite signal of the left and right audio signals.

(Function) According to the above configuration of the present invention, even when inputting 2-channel audio in a high-definition television system having a 4-channel speaker arrangement, the effect of providing a different sense of presence from the left, right, center, or rear speakers is achieved. can demonstrate.

(Example) An example of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram of a high-definition television audio conversion circuit according to the present invention.

Numbers 1, 2, and 3.4 in the figure are on the right and rear, respectively.

The left and center 4 channel audio input terminals are 15°16
, 17.18 are audio output circuits for each of the four channels, and 21.22.23.24.25 are speakers for a 3-1 audio system for high-definition television having 3 channels in the front and 1 channel in the rear. A plurality of 22.23 rear speakers are provided.

When 4 channels of independent audio input are applied to the audio input terminals 1, 2, 3.4, the input detector 8 detects that the 4 channels of audio input are applied, and switches the switch. SW■13. SW■14. SW■19.
All the SWs 20 are tilted upward as shown in FIG. 1, and the independent audio inputs of the four channels pass through the respective audio output circuits 15 to 18, and audio output signals are directly applied to the speakers 21 to 25 of each channel.

In addition, each switch (12 to 14) by the input detector 8
．． 19 and 20) can also be manually switched by the controller 10.

On the other hand, when only two channels of right audio and left audio are given as audio input, four channels of audio are created in a pseudo manner using the method described below.

First, the center speaker 25 is positioned for bass reproduction emphasis, and the center channel audio signal is obtained by adding the right audio signal and the left audio signal using the adder 9, adjusting the gain using the amplifier 26, and specifying the audio signal using the LPFII. Only the frequency components below are extracted and applied to the central speaker 25 via the switch SW14 and the central audio output circuit 18. Note that the frequency characteristics of LPFII can be variably adjusted within a certain range by the controller 10.

In addition, when inputting 2 channels, the input detector 8
Switch SW■tz, sw■13. swQc14,S
W■19. SW ■20 are all lying on the bottom side.

Further, the right audio signal and the left audio signal are also applied to a subtracter 5, and the subtracted audio signal (R-L) is subjected to a phase conversion operation by a function f in a 1-phase conversion circuit 6, and is then sent to the subtracter. 5' and adder 7. In the subtracter 5', the function f(RL) is subtracted from the original signal R of the right audio signal.

This becomes a signal R, -f (R-L), and after the gain is adjusted by the amplifier 27, it is applied to the right audio output circuit 15 via the switch SW12. In the adder 7, the original signal of the left audio signal and the function f(RL) are added, and L
After the gain is adjusted by the amplifier 28, the signal is applied to the left audio output circuit I7 via the switch SW13.

The audio output signals from the right audio output circuit 15 and the left audio output circuit 17 are output to the right speaker 21 and the left speaker 2, respectively.
4 and is inserted in series between the + (plus) terminals of the right speaker 21 and the left speaker 24, respectively. It is also applied to the rear speaker 23 as a composite signal.

Note that the function f indicating the characteristics of the phase conversion circuit 6 is as follows.

The controller 10 allows variable adjustment within a certain range.

The controller 10 also includes a right audio output circuit 15°, a rear audio output circuit 16. Left audio output circuit 17. The audio output level of the central audio output circuit 18 can be controlled independently.

With the above-described configuration, even when only two-channel audio input signals are provided, the effect of the four-channel speaker arrangement can be maximized.

(Effects of the Invention) As described above, the present invention achieves the effect of a four-channel speaker arrangement of three channels in the front and one channel in the rear (3-1 system), regardless of whether the audio input is 4 channels or 2 channels. It can be used to its fullest potential as a voice system.

The combination of the definition of high-definition television and large-screen images has a great effect on enhancing the sense of realism.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a high-definition television audio conversion circuit according to an embodiment of the present invention, and FIG. 2 is a speaker arrangement diagram of a 4-channel audio system (3-1 system) for high-definition television. FIG. 3 is a block diagram of a conventional high-definition television audio circuit. 5... Subtractor R-L, 5'... Subtractor R-f (R
-L), 6...phase conversion circuit. 7...Adder L+f(R-L), 8...Input detector, 9...Adder R+L, 10...Controller, 11...LPF. Figure 2 Patent applicant Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] In a television system with a four-channel speaker arrangement consisting of left, right, center, and rear speakers, in a high-definition television audio conversion circuit where only two left and right channels of audio signals are provided, the low frequency of the added left and right audio signals is A central audio output signal from which only the components have been extracted and the subtracted left and right audio signals are phase-converted using a phase conversion circuit, and left and right audio output signals are added and subtracted from the phase-converted signal to synthesize the left and right audio signals. An audio conversion circuit for high-definition television that generates rear audio output signals consisting of signals and drives each speaker of four channels with each audio output signal.