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JPH06133398

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JPH06133398
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
surround circuit for performing signal processing of phase delaying a difference (R-L) signal
between an R channel signal and an L channel signal and adding and subtracting it again to an R
channel signal and an L channel signal. The present invention relates to a sound reproducing
apparatus having
[0002]
2. Description of the Related Art In recent years, in order to reproduce a richer sense of reality, a
sound reproducing apparatus is often incorporated with a surround function. Hereinafter, an
example of the above-mentioned conventional sound reproduction apparatus will be described
with reference to the drawings.
[0003]
FIG. 4 shows a circuit configuration of a conventional sound reproducing apparatus. In FIG. 4, 1
is an R channel signal input terminal, 2 is an L channel signal input terminal, 3 is an (RL) signal
detection circuit, 4 is a phase delay circuit, and S1 is a surround ON / OFF switch. A1 and A2 are
buffer amplifiers, C1, C2, C3 and C4 are coupling capacitors, 11 is a mixing circuit on the R
channel side, 12 is a mixing circuit on the L channel side, and 10 is a reference voltage source,
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The (R-L) signal detected by the (R-L) signal detection circuit 3 is delayed by the phase delay
circuit 4 (.DELTA.t), and is mixed into the mixing circuits 11 and 12 when the surround ON is
turned on by the surround ON / OFF switch S1. It is supplied and switched so as not to be
supplied to the mixing circuits 11 and 12 when the surround is OFF. In the reference voltage
source 10, R16 is a resistor, D1 is a Zener diode, C11 is a capacitor, current is supplied from the
power supply Vcc through the resistor R16, and the voltage is made constant by the Zener diode
D1. It is stabilized by the capacitor -C11 and outputs the reference voltage Vref.
[0004]
In the mixing circuit 11, R23, R24 and R25 are resistors, A12 is an operational amplifier, and the
(R−L) signal is supplied to the minus input through the resistor R23, and the R channel signal is
supplied through the R24. Also, a resistor R25 is connected between the negative input and the
output. The positive input is connected to the reference voltage Vref. In this conventional
example, the resistors R23, R24 and R25 have the same resistance value, the gain for the R
channel signal is R25 / R23 = 1, and the gain for the (R−L) signal is R25 / R24 = 1. Further, in
the mixing circuit 12, R26, R27, R28 and R29 are resistors, A13 is an operational amplifier, the L
channel signal is supplied to the minus input through the resistor R26, and the resistor R25 is
between the minus input and the output Connected, the (R−L) signal is supplied to the plus
input via the resistor R27, and the plus input is connected to the reference voltage Vref via the
resistor R29. In this conventional example, the resistors R26, R27, R28 and R29 have the same
resistance value, the gain for the L channel signal is R28 / R26 = 1, and the gain for the (R−L)
signal is R29 / (R27 + R29) × (R26 + R28) / It becomes R26 = 1.
[0005]
Next, VR1 and VR2 are volume volumes, A8 and A9 are power amplifiers, C7, C8, C9 and C10 are
coupling capacitors, SP1 and SP2 are speakers, and the output of the mixing circuit 11 is Is input
to the power amplifier A15 through the coupling capacitor C3, the volume volume VR1 and the
coupling capacitor C26, and the output is further input to the speaker SP1 through the coupling
capacitor C28. , Acoustically reproduced. On the other hand, the output of the mixing circuit 12
is input to the power amplifier A16 via the coupling capacitor C4, the volume volume VR2 and
the coupling capacitor C27, and the output is further transmitted via the coupling capacitor C29.
The speaker SP2 is inputted to reproduce the sound.
[0006]
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The operation of the sound reproducing apparatus configured as described above will be
described below. At the time of surround ON, the surround ON / OFF switch S1 is switched to the
ON side, and an output of R + Δt (R−L) is obtained from the speaker SP1 on the R channel side,
and from the speaker SP2 on the L channel side An output of L−Δt (R−L) is obtained.
[0007]
Next, the operation of the phase delay circuit 4 will be described with reference to FIG. FIG. 2
shows a phase delay circuit using an operational amplifier. R17 to R22 are resistors and have the
same resistance value Rd, C12 and C13 are capacitors and have the same capacitance value Cd,
and A10 and A11 are operational amplifiers. Here, the phase delay amount φ of the phase delay
circuit 4 is
[0009]
The amount of time delay Δt is
[0011]
【0011】となる。
[0012]
However, the above-mentioned conventional sound reproducing apparatus delays the phase of
the difference signal (R-L) of the R channel signal and the L channel signal, and again performs
the R channel signal and the L channel signal. The output of the R channel side of the surround
circuit that performs signal processing to add and subtract is R + Δt (R-L), and the output of the
L channel side is L-Δt (R-L). When many components of (R−L) are mixed, the ratio of in-phase
components of the R channel and L channel decreases.
In particular, in a source having a vocal, the vocal generally has the above-mentioned in-phase
component in many cases, and there is a problem that the vocal level is lowered and localized
backward. It was
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[0013]
SUMMARY OF THE INVENTION The present invention has been made in view of the abovedescribed conventional problems, with the object of providing an audio reproduction apparatus
which is high in the effect of surround sound, and in which the vocal level is not lowered
backward.
[0014]
SUMMARY OF THE INVENTION In order to solve the above problems, the sound reproducing
apparatus according to the present invention comprises a signal detection circuit (R-L) for
detecting a difference signal between an R channel signal and an L channel signal, and its
detection. A first phase delay circuit for delaying the phase of the output (R−L) signal, an (R + L)
signal detection circuit for detecting a sum signal of the R channel signal and the L channel
signal, and a detected (R + L) A band-pass filter for detecting and outputting a mid-range signal
among the signals, a second phase delay circuit for delaying the phase of the signal outputted by
the band-pass filter, one of the R channel signal and the L channel signal A first mixing circuit for
adding the output signal of the first phase delay circuit and the band, the output signal of the
filter to the channel signal, and the other phase signal to the first phase delay circuit It is
obtained by a second mixing circuit for adding the output signal of the band-pass filter whose
phase has been delayed by the second phase delay with subtracts the output signal.
[0015]
According to the present invention, the midrange signal of the (R + L) signal is mixed to the R
channel and L channel signals according to the above-described configuration to correct the inphase component of the midrange of the R channel and L channel, and to mix to the R channel.
The second phase delay circuit generates a phase difference between the middle band signal of
the (R + L) signal and the middle band signal of the (R + L) signal mixed to the L channel, and the
sound image moves forward.
[0016]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the
sound reproducing apparatus according to the present invention will be described in detail with
reference to FIGS.
[0017]
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FIG. 1 is a circuit diagram of a sound reproduction apparatus according to an embodiment of the
present invention.
In FIG. 1, 1 is an R channel signal input terminal, 2 is an L channel signal input terminal, 3 is an
(RL) signal detection circuit, 4 is a phase delay circuit, and S1 is a surround ON / OFF switch.
A1 and A2 are buffer amplifiers, C1, C2, C3 and C4 are coupling capacitors, and 10 is a reference
voltage source, which is a circuit similar to the above-described conventional example.
5 is a (R + L) signal detection circuit, 6 is a band pass filter, 7 is a second phase delay circuit, 8 is
a mixing circuit on the R channel side, and 9 is a mixing circuit on the L channel side.
[0018]
In the (R + L) signal detection circuit 5, R10 and R11 are resistors, and the output of the buffer
amplifier A1 on the R channel side is further connected via the resistor R10, and the output of
the buffer amplifier A2 on the L channel side is connected via the R11 The sum signal of the
signal and the L channel signal is detected.
Next, in the band pass filter 6, R12 to R15 are resistors, C5 and C6 are capacitors, A6 is an
operational amplifier, A7 is a buffer amplifier, and (R + L) signal detected by the (R + L) signal
detection circuit 5 Is input to the positive input of the operational amplifier A6, the positive input
of the operational amplifier A6 is connected to the reference voltage Vref via the resistor R12,
and is further grounded via the capacitor C5.
The resistor R12 biases the operational amplifier A6 and determines the signal level of the (R +
L) signal input to the + input, and the capacitor -C5 has a cutoff frequency fc,
[0020]
A low pass filter is constructed. The negative input of the operational amplifier A6 is connected
to the output of the operational amplifier A6 through the resistor R13, and is further connected
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to the reference voltage Vref through R14, and the gain of the operational amplifier A6 is set by
the resistors R13 and R14.
[0022]
It is set to: Furthermore, the output of the operational amplifier A6 is connected to the input of
the buffer amplifier A7 via the capacitor C6, the input of the buffer amplifier A7 is connected to
the reference voltage Vref via the resistor R15, and cut by the capacitor C6 and the resistor R15.
Off frequency fc
[0024]
A high-pass filter to be formed is configured, and a band-pass filter is configured by combining
with a low-pass filter. In this embodiment, a band pass filter with a center frequency of 1 kHz is
used, and a midrange signal of (R + L) signal is detected.
[0025]
The second phase delay circuit 7 has the same circuit configuration as that of the first phase
delay circuit 4 and is a phase delay circuit using the operational amplifier shown in FIG. It is
connected to the output of the amplifier A7 and adds a phase delay to the midrange signal of the
(R + L) signal.
[0026]
S2 and S3 are surround ON / OFF switches, linked to the surround ON / OFF switch S1, and the
ON side movable piece of the surround ON / OFF switch S2 is used as an output of the buffer
amplifier A7 of the band pass filter 6. The OFF-side movable piece is connected to the reference
voltage Vref, the ON-side movable piece of the surround ON / OFF switch S3 is connected to the
output of the second phase delay circuit 7, and the OFF-side movable piece is the reference
voltage Connected to Vref.
[0027]
In the mixing circuit 8, R1 to R4 are resistors, A4 is an operational amplifier, the (R−L) signal is
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supplied to the minus input through the resistor R1, the R channel signal is supplied through the
R2, and further The negative input is connected via R3 to the common piece of the surround on /
off switch S2, and the resistor R4 is connected between the negative input and the output of the
operational amplifier A4.
The positive input is connected to the reference voltage Vref.
In this conventional example, the resistors R1 to R4 have the same resistance value, the gain for
the R channel signal is R4 / R2 = 1, the gain for the (R−L) signal is R4 / R1 = 1, and the
midrange of the (R + L) signal The gain for the signal is R4 / R3 = 1.
[0028]
Next, in the mixing circuit 9, R5 to R9 are resistors, and A5 is an operational amplifier. An L
channel signal is supplied to the-input of the operational amplifier A5 via the resistor R5, and a
negative input is applied to the common piece of the surround on / off switch S3 via the resistor
R6 and further via the operational amplifier via the resistor R4. Connected to the output of A5.
The (R−L) signal is supplied to the plus input of the operational amplifier A5 via the resistor R7,
and the plus input is connected to the reference voltage Vref via the resistor R9. In this
embodiment, the resistors R5 to R8 have the same resistance value, and R9 is 1/2 of the
resistance value of the resistors R5 to R8. The gain for the L channel signal is R8 / R5 = 1, (R + L)
signal The gain for the midrange signal is R8 / R6 = 1. The gain for the (R−L) signal is
[0030]
【0030】となる。 Next, VR1 and VR2 are volume volumes, A8 and A9 are power amplifiers,
C7, C8, C9 and C10 are coupling capacitors, SP1 and SP2 are speakers, and the output of the
mixing circuit 8 is , And is input to the power amplifier A8 via the coupling capacitor C3, the
volume volume VR1 and the coupling capacitor C7, and the output of the power amplifier A8 is
coupled to the speaker SP1 via the coupling capacitor C9. Is input to the sound reproduction. On
the other hand, the output of the mixing circuit 9 is input to the power amplifier A9 via the
coupling capacitor C4, the volume volume VR2 and the coupling capacitor C8, and the output of
the power amplifier A9 is the coupling capacitor C10. Is input to the speaker SP2 via the speaker
to reproduce the sound.
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[0031]
The operation of the sound reproducing apparatus configured as described above will be
described below. When surround is on, the surround on / off switches S1 to S3 are switched to
the on side, and the delay amount of the first phase delay circuit 4 is Δt1, and the delay amount
of the second phase delay circuit 7 is Δt2. From the side speaker SP1
[0033]
The output of L channel side is obtained from the speaker SP2 of the L channel side.
[0035]
When the surround is OFF, the surround ON / OFF switches S1 to S3 are switched to the OFF
side, the common piece is installed, and the speaker SP1 to R of the R channel side are installed.
The signal is output, and L is output from the speaker SP2 on the L channel side, and a normal
stereo state is established.
[0036]
FIG. 3 is an acoustic output characteristic diagram from each speaker when the same signal is
input to the R channel signal input terminal 1 and the L channel signal input terminal 2 at
surround ON, where A is an R channel signal and L is the L channel signal level, and B is the (R +
L) signal level at which the midrange is detected by the band pass filter 6.
[0037]
As described above, according to the present invention, the (RL) signal detection circuit for
detecting the difference signal between the R channel signal and the L channel signal, and the
phase delay of the detected (RL) signal The first phase delay circuit to be detected, an (R + L)
signal detection circuit that detects the sum signal of the R channel signal and the L channel
signal, and a midrange signal among the detected (R + L) signals Band-pass filter, a second phase
delay circuit for delaying the phase of the signal output from the band-pass filter, and the first
phase delay circuit for one of the R channel signal and the L channel signal. A first mixing circuit
for adding the output signal of the filter, the band, and the output signal of the filter, and
subtracting the output signal of the first phase delay circuit from the other channel signal, and
The second mixing circuit for adding the output signal of the band-pass filter phase-delayed by
the delay circuit is provided, so the effect of the surround is high, and the vocal (mid range) is not
lowered and is not localized backward. An audio player can be provided.
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