JPH0128395B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an electronic musical instrument in which delay time modulation is applied to a musical tone signal using an analog shift register such as a BBD (Bucket Brigade Device) or a CCD (Charge Coupled Device). The present invention relates to a modulation device for use in a computer.

As a conventionally proposed modulation device of this type, there is one disclosed, for example, in Japanese Patent Publication No. 52-38888. Such modulation devices use low-frequency waves of different frequencies to electronically simulate the sound image movement effect (so-called tremolo effect or chorus effect) produced by rotating a speaker or a rotating body provided in front of it with a motor. Attempts have been made to mix signals to form a modulation signal, use this modulation signal to frequency-modulate the shift pulse of the BBD, and apply delay time modulation to the musical tone signal. and,
In order to more faithfully simulate the sound image movement effect caused by motor rotation, it is preferable to produce an inertial effect similar to that at the time of starting the motor, and to achieve this, the frequency of the modulation signal is gradually increased at the start of modulation. However, this had the disadvantage that the sound image movement effect after the modulation rise would not stand out because the sound image movement effect would occur during the modulation rise as well as after the modulation rise.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel modulation device for an electronic musical instrument that can emphasize both the inertial effect during the rise of modulation and the sound image movement effect after the rise of modulation.

The modulation device according to the present invention is characterized in that during the rise of modulation, mixing of low frequency signals is stopped and a modulation signal is formed using a single low frequency signal. The illustrated embodiment will be described in detail.

The figure shows a modulation device for an electronic musical instrument according to an embodiment of the present invention, in which 10 indicates a musical tone signal TS corresponding to the operated key each time a key (not shown) is operated.
The musical tone signal TS is input in parallel to analog shift registers 20, 22, and 24 consisting of BBDs. And these BBD20, 22,
24 are driven by mutually opposite phase shift pulses supplied from corresponding voltage controlled variable frequency oscillators (VCO) 21, 23, and 25, respectively.
Control input voltage R, S of VCO21, 23, 25,
BBD20, by periodically changing T as described later and frequency modulating the output pulse.
The musical tone signals passing through 22 and 24 are subjected to delay time modulation.

Modulated musical tone signals sent from the BBDs 20, 22, 24 are supplied to sound systems 40, 42, 44 via corresponding low pass filters (LPF) 30, 32, 34, respectively, and are generated. Here, the LPFs 30, 32, and 34 are for reducing noise caused by shift pulses. The musical sounds generated from the sound systems 40, 42, and 44 are accompanied by a so-called tremolo effect in which a sound image moves in space.

Next, we will explain the circuit that forms the modulation signals R, S, and T, which are the control input voltages of the VCOs 21, 23, and 25. 50 is a tremolo effect addition switch.
The switch status signal A generated when SW is switched from the “0” signal source to the “1” signal source is maintained for a predetermined period t ₀
A delay circuit 52, which includes a one-shot circuit, converts the switch state signal A into a control signal C which rises exponentially with a predetermined time constant. 60 and 62 are low frequency oscillators (LFOs) that generate sine wave signals that gradually rise to a steady frequency of 7.0 Hz and 0.7 Hz, respectively, in response to the control signal C; 70 and 72 are LFOs 60 and 72; 62
Phase shift circuits 74 and 76 phase shift the output signals of phase shift circuits 70 and 72 by 120 degrees, respectively, and LFOs 60 and 6 phase shift the output signals of phase shift circuits 70 and 72 by 120 degrees, respectively.
This is a phase shift circuit that outputs a signal whose phase is shifted by 240 degrees with respect to the 0 degree output signal of No. 2.

The modulation signal R is derived via the resistor R ₁₁
The modulation signal S is formed by mixing the 0° output signal of the LFO 60 and the 0° output signal of the LFO 62 derived via the gate element G ₁ and the resistor R ₂₁ .
Formed by mixing the 120° output signal of the phase shift circuit 70 derived via _R12 and the 120° output signal of the phase shift circuit 72 derived via the gate element _G2 and resistor _R22 . The modulation signal T is composed of the 240° output signal of the phase shift circuit 74 derived through the resistor R ₁₃ and the output signal of the phase shift circuit 76 derived through the gate element G ₃ and the resistor R ₂₃ . Formed by mixing. The gate elements _G1 to _G3 are controlled by the control signal B, and are non-conductive when the control signal B is at the "0" level and conductive when the control signal B is at the "1" level.

In the operation of the modulation signal forming circuit described above, the tremolo effect addition switch SW is changed from "0" to "1".
When switching to , the delay circuit 50 and the time constant circuit 52
generate control signals B and C, respectively. As control signal C gradually rises, LFO60 and LFO6
2 gradually increases its oscillation frequency toward steady frequencies of 7.0 Hz and 0.7 Hz, respectively. In the process of increasing the oscillation frequency, the control signal B remains at the "0" level for about 1 to 2 seconds after the switch SW is switched, so that the gate element G ₁
~ _G3 becomes non-conductive during its “0” level period,
Preventing signal mixing via resistors _R21 to _R23 .
Then, when the control signal B changes from "0" to "1" level, the gate elements G ₁ to _{G 3} become conductive, and the resistors R ₂₁ to
Signal mixing occurs via _R23 .
Therefore, the modulation signals R, S, and T are LFOs 60 and 62.
In the process where the oscillation frequency is increasing, signals of 0°, 120°, and 240° are formed alone through the resistors R ₁₁ , R ₁₂ , and R ₁₃ , respectively, but when the oscillation frequency reaches a steady value, 0° via resistors R ₁₁ , R ₁₂ , R ₁₃ ,
For 7.0Hz signals of 120° and 240°, resistors R ₂₁ and
Since the 0.7Hz signals of 0°, 120°, and 240° via R ₂₂ and R ₂₃ are mixed, the modulation signals R, S,
T is formed by a 7.0Hz-0.7Hz mixed signal of 0°, 120°, and 240°.

Therefore, in the above-mentioned modulation device, during the rise of modulation, modulation is performed based on one modulation signal, so the inertial effect is emphasized and the sound image movement effect is suppressed, and after the rise of modulation, the modulation is performed by the mixed modulation signal. As a result, the sound image movement effect is emphasized, and the tremolo effect caused by motor rotation can be faithfully simulated.

In the above embodiment, the gate elements G ₁ to _{G 3} are configured to prevent the lower (0.7 Hz) signal from being mixed, but this is because this is preferable in terms of effectiveness, and the effect may be slightly reduced. Mixing of higher (7.0 Hz) signals may be prevented if permissible.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a modulation device for an electronic musical instrument according to an embodiment of the present invention. 20, 22, 24...analog shift register,
R ₁₁ - _{R 13} , R ₂₁ - _{R 23} ... Resistance for mixing, G ₁ - _{G 3} ... Gate element for mixing control.

Claims (1)

[Scope of Claims] 1 (a) a modulation effect addition switch; (b) means for generating a frequency control signal that gradually rises based on the operation of the modulation effect addition switch; and (c) the modulation effect addition switch. (d) means for generating a mixed control signal with a time delay approximately corresponding to the rising period of the frequency control signal from the time of the operation based on the operation of the signal; A first low frequency signal that gradually rises is sent out as a first modulation signal, and a second low frequency signal having a different frequency is mixed with the first low frequency signal in accordance with the mixing control signal. a modulated signal forming means for transmitting a signal as a second modulated signal following the first modulated signal; A modulation device for an electronic musical instrument, comprising: modulation means for applying modulation and transmitting; and (f) means for converting an output signal of the modulation means into sound.