JPS628794B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention is based on BBD (Bucket Brigade).
This invention relates to a modulation device for electronic musical instruments that applies delay time modulation to a musical tone signal using an analog shift register such as a charge coupled device (device) or a charge coupled device (CCD).

This type of modulation device that has been proposed in the past includes one such as the one disclosed in Japanese Patent Publication No. 52-38888. When modulating musical tone signals, the modulation was too deep, making it difficult to hear. This is because BBD modulation is delay time modulation, and therefore deeper modulation is applied to higher frequency components.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel modulation device for an electronic musical instrument that can eliminate the difficulty of listening due to excessive modulation.

A modulation device according to the present invention is characterized in that the depth of delay time modulation is controlled in conjunction with a timbre selection operation, and embodiments shown in the accompanying drawings will be described in detail below.

The figure shows an electronic musical instrument equipped with a modulation device according to an embodiment of the present invention, in which reference numeral 10 sends out in parallel a number of rectangular wave sound source signals TS each having a frequency corresponding to a number of musical tones to be generated. A sound source circuit 12 is a key switch circuit that includes a number of key switches respectively linked to a number of keys, and sends out a key press signal KS for identifying the operated key;
Reference numeral 14 denotes an opening/closing circuit which opens/closes the sound source signal TS corresponding to the pressed key in accordance with the key press signal KS.

Opening/closing musical tone signal KT sent out from the opening/closing circuit 14
is a low pass filter (LPF) 16 and a transmission line 17
and a band pass filter (BPF) 18 in parallel. The frequency characteristics of LPF16 and BPF18 are determined to emphasize the tones of the flute and oboe, respectively, so LPF16 and BPF18
The musical tone signals passed through the BPF 18 have tone characteristics of a flute and an oboe, respectively. In addition, transmission line 1
Since 7 is not particularly provided with a filter, the musical tone signal passing through it has the tone characteristics of a clarinet. Here, the flute musical tone signal sent out from the LPF 16 is approximately sinusoidal and has few overtone components, but the clarinet and oboe musical tone signals sent out from the transmission path 17 and BPF 18 have many overtone components.

Tone selection switches S ₁ , S ₂ and S ₃ are connected to the output side of the LPF ₁₆ , the transmission line 17 and the output side of the BPF 18, respectively.
By inputting any one of S ₂ and S ₃ , musical tone signals having flute, clarinet, and oboe tones can be appropriately selected and transmitted.

Musical tone signals ST selected by turning on any of the switches _S1 to _S3 are input in parallel to analog shift registers 20, 22, and 24 consisting of BBDs. These BBDs 20, 22, 24 are connected to corresponding voltage controlled variable frequency oscillators (VCO) 21, 2.
It is driven by shift pulses of mutually opposite phase supplied from VCO21 and VCO25, respectively.
By periodically changing the control input voltages A, B, and C of BBDs 23 and 25 as described later, and frequency modulating the output pulses, delay time modulation is applied to the musical tone signals passing through BBDs 20, 22, and 24. ing.

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, to explain the circuits that form the modulation signals A, B, and C, which are the control input voltages of the VCOs 21, 23, and 25, 50 and 52 change the tremolo effect addition switches SW from the "0" signal source to the "1" signal source. Low frequency oscillators (LFOs) 60 and 62 generate sine wave signals of 7.0Hz and 0.7Hz, respectively, when switched to LFOs 50 and 60, respectively.
Phase shift circuits 64 and 66 shift the phase of the phase shift circuits 60 and 62 by 120 degrees, respectively. Here, if the output signals of LFO 50 and 52 are 0°, the output signals of phase shift circuits 64 and 66 are respectively
It is generated with a 240° phase shift. Then, the modulation signal A is 0 from the LFOs 50 and 52.
The modulated signal B is formed by mixing the 120° output signals from the phase shift circuits ₆₀ and 62 through resistors R ₁₂ and R _{22 ,} respectively. The modulation signal C is formed by mixing the 240° output signals from the phase shift circuits 64 and 66 through resistors R ₁₃ and R ₂₃ , respectively. . In this way, by mixing the 7.0 Hz signal and the 0.7 Hz signal to form the control signals A, B, and C, a richly varied tremolo effect can be obtained.

By the way, in order to control the modulation depth, a series circuit of a resistor R ₁ and a gate element G 1 and a resistor R ₂ are connected between the transmission paths of the modulated signals A, B, and C and the ground _point .
A series circuit including a resistor R 3 and a gate element G ₂ , a series circuit including a resistor R ₃ and a gate element G ₃ are connected as shown. The gate elements G ₁ , G ₂ , and G ₃ all become non-conductive when controlled with a potential of -V, and become conductive when controlled with a ground potential, and each control input terminal receives a control signal. CN is applied.

In the circuit that forms the control signal CN, switches _S21 and _S31 are the aforementioned clarinet tone selection switch _S2 and oboe tone selection switch _S3 , respectively.
Each movable contact is grounded, and each fixed contact is connected to a diode D ₁ , D ₂
are connected to the anodes of each. and,
The cathodes of the diodes D ₁ and D ₂ are connected to the −V potential source through the resistor R ₀ , and the resistor R ₀ and the diode
The control signal CN is taken out from the connection point with D ₁ and D ₂ .

Here, the control signal CN does not select a multi-harmonic timbre such as a clarinet or an oboe, but selects a switch.
If S ₂ or S ₃ is not closed, switch S ₂₁ or
Since S ₃₁ is in the open state, take the level of -V,
On the contrary, when the switch _S2 or _S3 is closed to select a multi-harmonic timbre, the switch _S21 or _S31 is closed, so that the ground potential level is taken. Therefore, the gate elements G ₁ to _{G 3} controlled by the control signal CN are non-conductive when a multi-harmonic timbre is not selected, but conductive when a multi-harmonic timbre is selected, and the resistors R ₁ to _{R 3} Ground one end of the Therefore, in the case of multi-harmonic timbre selection, the amplitude levels of modulation signals A, B, and C are
The voltage drop in R ₁ , R ₂ , R ₃ decreases to a value corresponding to the voltage drop in R 1 , R 2 , R 3 , and as a result, the frequency modulation depth in VCO 21, 23, 25 and, in turn, BBD 20, 2
The depth of the delay time modulation in Nos. 2 and 24 is shallower than when no multi-harmonic timbre is selected (for example, when a flute timbre is selected).

As mentioned above, controlling the modulation depth shallowly when selecting a multi-harmonic timbre eliminates the difficulty of listening due to excessive modulation, and produces an appropriate tremolo effect for musical tones with multi-harmonic timbres such as clarinet or oboe. This is extremely desirable in terms of musical effects.

In addition, in the above embodiment, in the case of multi-harmonic timbre selection, the two types of modulation signal levels of 0.7 Hz and 7 Hz were controlled to be lowered, but it may be controlled to lower the level of only the 7 Hz modulation signal. . That is, even if the modulation depth is the same, a modulation signal with a higher frequency has a larger contribution to the modulation effect, so it is sufficient to lower the level of only the modulation signal with a higher frequency.

Further, although the modulation depth is made shallow when selecting a multi-harmonic timbre, the modulation depth may be made deeper when selecting a sub-harmonic timbre such as a flute.

Furthermore, although an example has been shown in which a variable resistance circuit is used as the modulation depth control means, a variable low-pass filter circuit, a voltage-controlled variable gain amplifier (VCA), or the like may also be used.

Furthermore, as a modulation depth control mode, control is performed so that the modulation depth is different for each selected tone,
The optimum modulation depth may be obtained for each selected tone color according to its overtone component content.

[Brief explanation of the drawing]

The figure is a circuit diagram of an electronic musical instrument equipped with a modulation device according to an embodiment of the present invention. 20, 22, 24...Analog shift register, _S1 , _S2 , _S3 ...Tone selection switch, _S21 , _S31
... Modulation depth control switch, G ₁ , G ₂ , G ₃ ...
Gate element for modulation depth control.

Claims (1)

[Scope of Claims] 1 (a) timbre selection means; (b) musical tone signal generation means for generating a musical tone signal corresponding to the timbre selected by the timbre selection means; and (c) from this musical tone signal generation means. (d) a control means for controlling the depth of modulation in the modulation means in conjunction with the timbre selection operation by the timbre selection means; (e) A modulation device for an electronic musical instrument, comprising means for converting a musical tone signal sent from the modulation means into sound.