JPS6149600A - Acoustic field reproducing circuit - Google Patents

Abstract

PURPOSE:To produce an effective feeling of spread and presence by adding a phase shifted stereo difference signal to one original signal with the same phase and adding it to the other original signal with the opposite phase to drive the first and the second speakers and driving the third speaker with the difference signal. CONSTITUTION:Outputs of amplifiers 1 and 2 which amplify L and R channel signals of a stereo signal are subjected to subtraction by a subtractor 3, and the obtained difference signal is inputted to a phase shifter 4. The output has the level adjusted and is applied to a buffer amplifier 6. A part of the output passes a resistance 8 and is mixed with the original L channel signal with the same phase in the output side of a resistance 7, and the output is applied to an amplifier 12 to drive the first speaker 14. Meanwhile, a part of the output of the buffer 6 has the opposite phase by an inverter 9 and passes a resistance 11 and is mixed with the original R channel signal in the output side of a resistance 10, and the output is applied to an amplifier 13 to drive the second speaker 15. The difference signal which passes the buffer 6 is amplified by an amplifier 16 to drive the third speaker 17.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sound field reproducing circuit that can give a sense of spaciousness and realism to reproduced sound in a reproducing device such as a stereo device.

Conventional configurations and their problems In the past, there have been systems that reproduce sound fields using 4-channel stereo reproduction, such as discrete 4 channels and matrix 4 channels, to give a sense of spaciousness and presence to stereo reproduced sound. Ta. However, since both require the use of a source signal that has been converted in advance to enable 4-channel playback, it is necessary to prepare a playback device specific to each method depending on the method, and there is no compatibility between each method. I didn't want one -.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a sound field reproduction circuit that can effectively create a sense of spaciousness and presence using a general stereo source without using a special source.

Structure of the Invention The present invention detects a difference signal between both channel signals by subtracting both channel signals of a stereo signal, and converts the difference signal into both channel signals of the original stereo signal through a one-stage or multi-stage phase shifter. Mixing is performed in the normal phase and in the negative phase, and this mixed signal is sent to the first signal. The difference signal is added to the second power amplifier to drive the L and R channel speakers, and the difference signal is added to the third power amplifier to drive the third speaker, thereby providing a sufficient sense of spaciousness. That's how it is. Furthermore, since the difference signal between the L and R channel signals also detects reverberation components, a sufficient sense of realism can be obtained by amplifying and reproducing the difference signal.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a block diagram of a sound field reproduction circuit according to an embodiment of the present invention.

1.2 is an input amplifier that amplifies the input signal of each stereo channel. These surface output signals are input to the subtraction circuit 3. The difference signal detected by the subtraction circuit 3 is input to a phase shifter 4 connected in multiple stages. The output of the phase shifter 4 is level-adjusted by a variable resistor 5 and input to a buffer amplifier 6. A part of the output is mixed with the original L channel signal via a resistor 8 in positive phase on the output side of the resistor 7. This mixed signal is applied to the first power amplifier 12 and drives the first speaker 14. On the other hand, a part of the output of the buffer amplifier 6 is converted to the opposite phase L by the inverter amplifier 9, and returned to the original R via the resistor 11.
Mixed with the channel signal at the output side of the resistor 10,
A second speaker 15 is driven by a second power amplifier 13. Further, the difference signal that has passed through the buffer amplifier 6 is amplified by the third power amplifier 16 and drives the third speaker 17.

The above operation will be explained using equations. A subtraction circuit performs 100% subtraction on the L and R channel signals.

At this time, for the L channel signal, if M is the same signal included in both the L and R channels, and l is the signal recorded only in the L channel, then L = M + 4. becomes R=M+r. Therefore, the output of the subtraction circuit 3 is L−R=M+1−(M+
r)-#-r.

This l-r difference signal is transferred to a phase shifter 4 connected in multiple stages.
to shift the phase. Furthermore, the level of the phase-shifted signal is adjusted with a variable resistor, and the original L channel signal M
Add to 10l to obtain an output of m+g+(ir)). Similarly, a signal of M+r-(l-r) is obtained on the R channel. Since the l - r difference signal is phase shifted, the β or r components are not calculated mathematically. Therefore, β
-r are in opposite phases to each other in the speaker output, giving a sense of spaciousness to the reproduced sound.

Furthermore, the difference signal of 4-r is independently transmitted to the third power amplifier 1.
6 and drives the third speaker 17.

This makes it possible to create a spacious sound field that is impossible with conventional stereo.

In this case, if the third speaker 17 is placed laterally or behind the listener with respect to the speakers 14 and 16 placed at the front, it is possible to obtain a sense of presence with the β-r difference signal.

FIG. 2 shows another embodiment of the present invention, in which the difference signal (1-r) is reproduced by two speakers 17 and 20. That is, not only is the output signal of the buffer amplifier 6 in FIG. In addition to the amplifier 19, the output is amplified and the fourth speaker 20 is driven by the output. In this way, the difference signal of C6-r) is a single monaural signal, and the phase shifter 18 is used to prevent the sound image from being localized at the center of the third speaker 17 and the fourth speaker 2o. You can expand your space.

Note that in any of the embodiments, the difference signal is independently
Alternatively, it is amplified by the fourth power amplifier 16 or 19, but originally the difference signal was mixed with the original L and R channel signals in positive and negative phase, and a certain degree of realism was achieved in the front L and R channels. , the 3rd one amplifies the difference signal. The fourth power amplifier 16.19 is the front L
, R channel power amplifier 12.13, it is not necessary to have a large output.

Effects of the Invention The sound field reproduction circuit of the present invention phase-shifts the difference signal component between the L and R channel signals of a stereo signal using a phase shifter, and transfers this phase-shifted signal to either the L channel or the R channel. is added to the original signal in positive phase, and this added signal is added to the first power amplifier to drive the first speaker, and the phase-shifted signal is added to the other channel of either the L or R channel. The signal is added to the original signal in reverse phase, the added signal is added to a second power amplifier to drive a second speaker, and the phase-shifted signal is added to a third power amplifier to drive a third speaker. Since it is configured to drive speakers, it is possible to obtain a sense of spaciousness and presence that cannot be obtained with conventional stereo equipment.

Furthermore, unlike conventional 4-channel stereo systems, there is no source specificity, and a sufficient sense of spaciousness and realism can be obtained even with ordinary stereo sources.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a sound field reproduction circuit in one embodiment of the present invention, and FIG. 2 is a block diagram of a sound field reproduction circuit in another embodiment of the present invention. 1.2...Input amplifier, 3...Subtraction circuit,
4゜18... Phase sister, 5... Variable resistor, 6... Buffer amplifier, 7, 8, 10
．． 11...Mixing resistor, 9...Inverter amplifier, 12゜13.16.19...
1st. Second. Third. Fourth power amplifier, 14, 15,
17.20... River 1st 2nd. Third. 4th speaker. Name of agent: Patent attorney Toshio Nakao and 1 other ■Indication of case: 6 goo/t/>day 2: Name of the invention Sound field reproduction circuit 3: Person who makes amendments Connection with the case Patent application Address: Osaka prefecture 1006 Kadoma, Kadoma City
(582) Representative of Matsushita Electric Industrial Co., Ltd.
Toshihiko Yamashita 4 Agent 571 Address 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Form 6, Contents of amendment (1) "Obtain. Do the same." on page 5, line 6 of the specification. Correct it to ``obtain.(C1-γ)) indicates the phase-shifted version of the l-γ difference signal component.Similarly.'' (2) Correct all "14-γ" in lines 7, 9, 12, and 18 on page 6, and lines 1 and 9 on page 6 to "((l-γ))". (3) Correct the drawings 1 and 2 as shown in the attached sheet. Ward ---

Claims (1)

[Claims] The difference signal component between the L and R channel signals of the stereo signal is phase-shifted by a phase shifter, and this phase-shifted signal is added to the original signal of either the L or R channel in positive phase. The first signal
In addition to driving the power amplifier of A sound field reproducing circuit characterized in that it is configured to drive a second speaker in addition to the power amplifier, and further to add the phase-shifted signal to a third power amplifier to drive the third speaker. .