JPH0220167B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a fade-in/out circuit for a stereo sound reproduction device.

BACKGROUND ART A fade-in/out circuit changes the gain so that the acoustic output of a sound reproduction device gradually increases in response to a fade-in command and gradually decreases in response to a fade-out command.

FIG. 1 shows a conventional example of a fade-in/out circuit in a stereo sound reproduction device consisting of two left and right channels.

In this figure, the amplification system for each channel of the stereo sound reproduction device includes an L (left) channel and an R (right) channel.
VCAs (voltage controlled amplifiers) 1 and 2 are provided. On the other hand, a fade-in command signal generating circuit 5 consisting of a resistor 3 and a fade-in switch 4 is connected to the set terminal S of the RS flip-flop 6, and a fade-out command signal generating circuit 9 consisting of a resistor 7 and a fade-out switch 8 is connected to the set terminal S of the RS flip-flop 6. Connected to reset terminal R. The output terminal Q of the RS flip-flop 6 is connected to the VCA via an integrating circuit 12 consisting of a resistor 10 and a capacitor 11.
It is connected to the control terminals 1 and 2.

In the conventional fade-in-out circuit having such a configuration, first, when the fade-in switch 4 is turned on, the output voltage level (a) of the fade-in command signal generating circuit 5 changes from voltage +B to the ground level as shown in FIG. 6 is set. By setting the flip-flop 6, the output terminal Q
The voltage level (c) of is inverted from a low level to a high level as shown in FIG. 2c. This high level signal is integrated by the integrating circuit 12 and supplied to the control terminals of VCAs 1 and 2, so that the voltage level (d) at the control terminals gradually increases from a low level as shown in FIG. High levels are reached after T ₁ . Therefore, the gains of VCAs 1 and 2 gradually increase from -∞ to 0 dB and fade in within time T1 as shown in FIG. _2e .

Next, when the fade-out switch 8 is turned on, the output voltage level (b) of the fade-out command signal generating circuit 9 changes from the voltage +B to the ground level as shown in FIG. 2b, and the flip-flop 6 is reset. By resetting the flip-flop 6, the output terminal Q is inverted from a high level to a low level. Since this low level signal is integrated by the integrating circuit 12,
The voltage levels at the control terminals of VCA1 and VCA2 gradually decrease from a high level and reach a low level after time _T1 has elapsed. Therefore, the gains of VCAs 1 and 2 gradually decrease from 0 dB to -∞ within time T ₁ and fade out as shown in FIG. 2e.

By the way, in a stereo sound reproduction device,
It is preferable that a high stereo effect can be obtained also during fade-in and fade-out.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fade-in/out circuit for a stereo sound reproduction device that can provide a high stereo effect during fade-in and fade-out.

The fade-in/out circuit of the stereo sound reproduction apparatus of the present invention includes a delay means for delaying the start point of gain change of at least one of the two channels by a predetermined time period than the start point of gain change of the other channel, and The feature is that the sound image moves during the fade-out.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 3 and 4.

In FIG. 3, the same parts as those in the circuit in FIG.
It is also connected to the trigger end of the one-shot multivibrator 15. The output terminal Q of the one-shot multivibrator 15 has a resistor 1
6 and a capacitor 17 to a set terminal S of an RS flip-flop 19. On the other hand, the fade-out command signal generating circuit 9 is connected to the reset terminal R of the flip-flop 6 and also to the trigger terminal of the one-shot multivibrator 20. The output terminal Q of the one-shot multivibrator 20 is connected to a resistor 21.
It is connected to the reset terminal R of the flip-flop 19 via a differentiating circuit 23 consisting of a capacitor 22 and a capacitor 22. The output terminal Q of the flip-flop 6 is connected to the reverse switches 24 and 25 via the integrating circuit 12, and the output terminal Q of the flip-flop 19 is also connected to the reverse switches 24 and 25 via the integrating circuit 26.
It is connected to the. Reverse switch 24, 25
is interlocked and becomes normal state, reverse switch 2
4 supplies the output signal of the integrating circuit 12 to the control terminal of the VCA 1, and the reverse switch 25 supplies the output signal of the integrating circuit 12 to the control terminal of the VCA 1.
The output signal of is supplied to the control end of VCA2. In the reverse state, the reverse switch 24 is connected to the integrating circuit 2.
6 is supplied to the control terminal of VCA 1, and reverse switch 25 supplies the output signal of integration circuit 12 to the control terminal of VCA 1.
Supplied to the control end of VCA2. In order to set the pulse width generated by the one-shot multivibrator 15, 20, the one-shot multivibrator 15 is provided with a time constant circuit 29 consisting of a resistor 27 and a capacitor 28, and the one-shot multivibrator 20 is also provided with a resistor 30 and a time constant circuit 29. capacitor 3
A time constant circuit 32 consisting of 1 is provided. Further, the differentiating circuits 18 and 23 generate trigger pulses in response to the falling edge of the input pulse.

In the fade-in/out circuit according to the present invention having such a configuration, the reverse switches 24, 2
5 is in the normal state. When the fade-in switch 4 is turned on at time _t1 , the output voltage level (a) of the fade-in command signal generating circuit 5 changes from the voltage +B to the ground level as shown in FIG. 4a.
This ground level is supplied to the set end S of the flip-flop 6 as a fade-in command signal.
In response to the fade-in command signal, the voltage level (c) at the output terminal Q of the flip-flop 6 is inverted from a low level to a high level as shown in FIG. 4c. This high level signal is integrated by the integrating circuit 12, and the integrating circuit 1
The output voltage (i) of No. 2 gradually increases from a low level as shown in FIG. 4i and reaches a high level after time _T3 has elapsed. The operation up to this point is the same as that of the conventional example shown in FIG. Further, at time _t1 , a rectangular pulse having a pulse width _T2 is generated from the one-shot multivibrator 15 as shown in FIG. 4d in response to the fade-in command signal. This rectangular pulse is differentiated by the differentiating circuit 18, and at time _{t2 after time T2 has elapsed from time t1 ,} the differentiating circuit ₁₈ sends a trigger pulse (f) to the set end S of the flip-flop 19 as shown in FIG. Supplied.
Flip-flop 19 is set and its output Q
The voltage level (h) of is inverted from a low level to a high level as shown in FIG. 4h. This high level signal is integrated by the integrating circuit 26, and the output voltage of the integrating circuit 26 is
(j) gradually increases from a low level as shown in FIG. 4j and reaches a high level after time _T3 has elapsed. Therefore, VCA
The gain of 1 gradually increases from −∞ to 0 dB within time T ₃ from time t ₁ as shown in FIG.
The gain of 2 gradually increases from -∞ to 0 dB within time T ₃ from time t ₂ as shown in FIG. 4l. That is, a fade-in occurs in which the sound image gradually moves from left localization to the right and ends at central localization.

Next, when the fade-out switch 8 is turned on at time _t3 , the output voltage level (b) of the fade-out command signal generation circuit 9 becomes voltage ++ as shown in FIG. 4b.
B becomes the ground level, and this ground level is supplied to the reset terminal R of the flip-flop 6 as a fade-out command signal. In response to the fade-out command signal, the voltage level at the output terminal Q of the flip-flop 6 is inverted from a high level to a low level. This low level signal is integrated by the integrating circuit 12, and the output voltage of the integrating circuit 12 gradually decreases from the high level and reaches the low level after time _T3 has elapsed.
At time _t3 , the one-shot multivibrator 20 generates a rectangular pulse having a pulse width _T2 as shown in FIG. 4e in response to the fade-out command signal. This rectangular pulse is differentiated by the differentiating circuit 23, and at time _t4 after time T2 has elapsed from time _t3 , the differentiating circuit 23 sends a trigger pulse (g) to the reset terminal R of the flip-flop 19 as shown in _FIG . Supplied.
Flip-flop 19 is reset and the voltage level at its output Q is inverted from high to low. This low level signal is also integrated by the integrating circuit 26, and the output voltage of the integrating circuit 26 gradually decreases from the high level and reaches the low level after time _T3 has elapsed. Therefore, the gain of VCA1 is the time from time t ₃
gradually decreases from 0 dB to −∞ within T ₃ ,
The gain of VCA2 is within time T ₃ from time t ₄
Gradually decreases from 0dB to -∞. Therefore, a fade-out occurs in which the sound image gradually moves to the right from the central localization and ends at the right localization.

Further, when the reverse switches 24 and 25 are in the reverse state, the sound image moves from the right localization to the center localization during fade-in, and the sound image moves from the center localization to the left localization during fade-out.

Application Example FIG. 5 shows an application example of the present invention. In this diagram, in addition to VCA1 and 2, Lch and Rch
VCAs 31 and 32 are provided, VCAs 1 and 2 are supplied with the signal of the first music source, and VCAs 31 and 3 are supplied with the signal of the first music source.
2 is supplied with a signal of a second music source.
The output signals of VCA1 and VCA31 are combined by a mixer 33 and supplied to the left channel power system, and the output signals of VCA2 and VCA32 are combined by a mixer 34 and supplied to the right channel power system. be done. The output end of the flip-flop 6 is connected to the control end of the VCA 31 via an integrating circuit 35, and the output end of the flip-flop 19 is connected to the control end of the VCA 32 via an integrating circuit 36. In this case, when switch 8 is turned on,
The gain of VCA1 gradually decreases as shown in Figure 6a, and at the same time the gain of VCA31 gradually increases as shown in Figure 6c, and after a slight delay, the gain of VCA2 increases as shown in Figure 6b.
At the same time, the gain of the VCA 32 gradually increases as shown in FIG. 6d. Also, as shown in Figure 6, when switch 4 is on, the gain of VCA1 gradually increases and at the same time the gain of VCA31 gradually decreases, and after a slight delay, the gain of VCA2 gradually increases and at the same time the gain of VCA32 gradually decreases. do. Therefore, an automatic crossfader with a sound image movement alternation effect is obtained.

Effects As described above, in the fade-in/out circuit of the stereo sound reproduction device of the present invention, the start point of the change in the gain of at least one of the two channels is delayed by a predetermined period of time than the start point of the gain of the other channel. It is possible to perform fade-in or fade-out while moving the . Therefore, a high stereo effect can be obtained even during fade-in and fade-out.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional example of a fade-in/out circuit, FIG. 2 is a waveform diagram showing the operation of the circuit in FIG. 1, and FIG. 3 is a circuit diagram showing an embodiment of the present invention.
Figure 4 is a waveform diagram showing the operation of the circuit in Figure 3;
The figure is a circuit diagram showing an application example of the present invention, and FIG.
FIG. 3 is a waveform diagram showing the operation of the circuit shown in the figure. Explanation of the symbols of the main parts, 1, 2, 31, 32...
...VCA, 5...Fade-in command signal generation circuit,
6, 19...RS flip-flop, 9...Fade out command signal generation circuit, 12, 26, 3
5, 36... Integrating circuit, 15, 20... One-shot multivibrator, 18, 23... Differentiating circuit.

Claims (1)

[Claims] 1 A fade-in/out circuit that gradually increases the gain of each channel of a stereo sound reproduction device having at least two channels in response to a fade-in command and gradually decreases the gain in response to a fade-out command, wherein one of the at least two channels. 1. A fade-in/out circuit comprising delay means for delaying the start point of gain change of one channel by a predetermined time period than the start point of gain change of the other channel.