JPS5926035B2 - Modulation signal generator for electronic musical instruments - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a modulation signal generation device for an electronic musical instrument, and more particularly to a modulation signal generation device for generating a modulation signal for a delay vibrato effect.

Generally, as shown in FIG. 1, an electronic musical instrument such as an electronic organ is composed of a sound source circuit 1, an opening/closing circuit 2, a keyboard circuit 3, a tone forming circuit 4, etc., and the opening/closing circuit 2 is controlled by the keyboard circuit 3. , the tone forming circuit 4 selects and derives a tone source signal of a pitch corresponding to the key press from the tone source signal generated by the tone source circuit 1 by adding envelopes such as attack and sustain.
, an amplifier 5 and a speaker 6 as a musical tone signal.

In order to provide a delay vibrato effect in such electronic musical instruments, the sound source circuit 1 has conventionally been configured with a voltage-controlled variable frequency oscillator (hereinafter abbreviated as VCO), whose oscillation frequency changes depending on the voltage. As shown in FIG. 1, the vibrato signal from the modulation signal oscillator 8 for vibrato control is amplitude-modulated by the amplitude modulator 7 and supplied to the VCO of the sound source circuit 1 to control the sound source signal frequency. Configure.

On the other hand, the key press signal KON outputted from the keyboard circuit 3 in response to a key press as shown in FIG. Therefore, the one-shot multivibrator 10 is triggered to generate a pulse having a pulse width of time DT as shown in FIG. After short-circuiting and clearing the charging voltage, the charging voltage of the capacitor Cl caused by charging the power supply voltage +V applied through the variable resistor VRI was used as a modulation signal of the amplitude modulator T.

Therefore, the charging voltage of the capacitor Cl changes as shown in FIG. 2 2, and this charging voltage modulates the amplitude of the vibrato signal from the modulation signal oscillator 8 with a constant amplitude as shown in FIG. 2 E. Therefore, as shown in FIG. 2, the amplitude modulator 7 outputs a waveform that has no vibrato signal for a time DT from the moment the key is pressed, and then a waveform determined by the time constant of the variable resistor VR and the capacitor Cl. A vibrato signal whose amplitude increases in accordance with .

That is, in the case of an electronic musical instrument as shown in FIG. 1, the vibrato effect is applied with a delay of time DT after the key is pressed,
Thereafter, the speed of change in the vibrato depth can be adjusted by a variable resistor VR, but the change is monotonous and is within the range of the charging force curve of the capacitor C1, with a frequency that is preferable for hearing. It was impossible to make any arbitrary or irregular changes.

This invention was made in view of the above points,
A predetermined voltage is applied from a power supply to a voltage storage capacitor via a gate circuit, and the charging voltage of the capacitor is controlled by controlling the gate of this gate circuit with a pulse train whose pulse width or frequency changes periodically or randomly. An electronic musical instrument that makes it possible to control various effects that are pleasing to the sense of hearing in a purely electronic manner by changing the amplitude of a modulation signal for effect control such as a vibrato signal by changing the charge voltage over time in a complicated manner. The present invention provides a modulated signal generator.

The present invention will be described below with reference to the accompanying drawings.

FIG. 3 is a block circuit diagram showing an embodiment of the present invention, and the same parts as those in FIG. 1 are given the same reference numerals and their explanation will be omitted. In FIG. 3, 12 is a pulse train generator 1
R2 is a variable resistor that adjusts the output of the modulation signal oscillator 8, VR3 is a variable resistor that adjusts the oscillation frequency of the modulation signal oscillator 8, KSl, KS2, . . . . . . shows a part of a keyboard switch included in the keyboard circuit 3 in FIG. 1, which is turned on in response to a key depression and generates a key depression signal KON.

FIGS. 4A to 4C are waveform diagrams shown for explaining the operation of the embodiment of FIG. 3. Gate circuit 12, for example FE
It consists of a switching element such as T, whose gate is controlled by a pulse train from a pulse train generator 13, and is turned on only during the pulse application period to connect the power supply voltage +
is applied to capacitor C1.

Therefore, the capacitor C1 is repeatedly charged in response to the pulse train from the pulse train generator 13, and its charging voltage gradually increases until it finally stores the voltage +V.

When, for example, the keyboard switch KSl is turned on by pressing a key, the one-shot multipipulator 10 is triggered via the differentiating circuit 9 at the rising edge of the key pressing signal KON, and a pulse (pulse width) as shown in FIG. 4A is generated. DT), the switching element 11 is turned on only for the time DT, the capacitor C1 is short-circuited, and its charging voltage +V is cleared.

Therefore, when the switching element 11 is turned off after a time period DT equal to the width of the output pulse of the one-shot multipipulator 10 has elapsed, a voltage +V is applied to the capacitor C1 via the gate circuit 12 and the resistor R, and the capacitor C1 is charged again. Start.

If the pulse train generated from the pulse train generator 13 has a waveform as shown in FIG. After DT, the waveform rises in a stepwise manner.

If voltage +V is applied directly to capacitor C1 through resistor R1,
If the charging voltage is applied continuously, the charging voltage will rise quickly with a small time constant determined by the relatively small value of the resistor R1 and the capacitor C1, as shown by the broken line in Figure 4C. In comparison, gate circuit 12 and pulse train generator 13
By intermittently charging the capacitor C1, the result is substantially the same as when the time constant is increased by increasing the value of the resistor R1, and the degree of increase becomes gradual.

For convenience of illustration, the number of pulses in the pulse train is shown as small, but in reality, by increasing the frequency of the pulse train and controlling the frequency or pulse width as appropriate, the charging voltage of capacitor C1 is almost smooth. The charged voltage of the capacitor C1 is applied to the amplitude modulator 7 to amplitude-modulate the output signal of the modulation signal oscillator 8, and the output signal of the modulated signal oscillator 8 is amplitude-modulated, and the vibrato signal is applied to the modulated circuit, for example, the sound source circuit 1 in FIG. By adding it as a signal, it is possible to create a complex delay vibrato effect.

Next, the pulse train for controlling the gate of the gate circuit 12 is
The pulse train generation circuit 13 that generates pulses by periodically or randomly changing the pulse width or frequency will be described.

FIG. 5 is a block circuit diagram showing a specific example of a pulse train generation circuit 13 that generates a pulse train whose frequency can be varied with a constant pulse width. CO15, which oscillates a signal with a waveform having a steep rise or fall at
A constant pulse width circuit always outputs a pulse train of a constant pulse width regardless of the oscillation frequency of the CO14, and 16 is a mixing circuit that mixes three types of input voltages and controls the oscillation frequency of the VCO14 by the mixed voltage.

Reference numeral 17 includes an oscillator 19 that repeatedly generates a signal with the same waveform periodically, such as a sine wave or a triangular wave, and a noise generator 2.
It is a periodic/aperiodic signal source consisting of a rectifier detector 21 and the like that rectifies and detects a random noise signal generated from zero to generate a signal whose waveform changes randomly.

18 is a touch response circuit, and key switches KSl, K
S2, KS3, . . . and touch detection switches KSWl, KSW whose contacts change in conjunction with the key switches KS, KS2, KS3, . . .
2, KSW3, ......, voltage hold capacitor C2, voltage discharge capacitor C3, resistor R2,
Wraparound prevention diodes Dl, D2, D3,...
. . . Consists of a switching element 22 and a differentiating circuit 23, and generates a voltage according to the speed of key depression.

R4 is a variable resistor that divides the power supply voltage +V, and the DC voltage divided by this variable resistor VR4 controls the oscillation frequency of the VCO14 via the mixing circuit 16, and produces a pulse train output from the constant pulse width circuit 15. To change the pulse interval, the effective time constant changes as described in the embodiment of FIG. 3, and the charging speed of capacitor C1 is adjusted by variable resistor VR4.

The output signal of the periodic/aperiodic signal source 17 is switched from the OFF state to the oscillator 19 or the rectifying detector 21 by the select switch SWl, and becomes the other input of the mixing circuit 16, so that it is converted into a DC signal by the variable resistor VR4. The oscillation frequency of the VCO14 is further changed periodically or non-periodically (randomly) by being superimposed on the voltage, and the charging voltage of the capacitor C1 is increased while changing periodically or non-periodically.
Next, with reference to Figure 6 A, the touch response circuit 1.
The operation of No. 8 will be explained. In the touch response circuit 18 in FIG. 5, the capacitor C2 and the switching element 22 are common to each key, but the key switch KS, (K
S2......), differentiator circuit 23, touch detection switch KSWl (KSW2......), capacitor C3, etc. are provided for each key, and their operations are the same. I will explain one key.

Until the key is pressed, the touch detection switch KSWl is in the position shown in the figure, voltage +V is applied through contact a, and capacitor C3 is charged to voltage +.

The key switch KSl is turned on by pressing the key, and voltage +V is applied to the differential circuit 23, and a differential pulse as shown in FIG. is short-circuited, and the charging voltage V1 of the capacitor C2 caused by the previous key press is cleared.

In addition, when the key switch KSl is turned on, the touch detection switch KSWl also switches from contact a to b at a speed corresponding to the key pressing speed, so when the movable contact c leaves contact a, the capacitor C3 The charge is connected in parallel to the resistor R.
2, and the voltage drops as shown by the broken line in FIG. 6 according to a time constant determined by capacitor C3 and resistor R2.

At the moment when the movable contact piece c touches the contact point b, the residual voltage V2 of the capacitor C3 at that moment passes through the diode D1.
is transferred to capacitor C2 and held, and diode D
Capacitor C without backflow due to the unidirectionality of 1
2 stores this voltage V2.

That is, the voltage of the capacitor C2 before and after the key is pressed changes as shown by the solid line in FIG.
Since the time t during which the movable contact piece e of 1 moves from the contact point a to the contact point b corresponds to the key pressing speed, a voltage 2 corresponding to the key pressing speed is obtained from the touch response circuit 18.

This voltage V2 is added to the DC voltage generated by the variable resistor R4 via the mixing circuit 16 by turning on the select switch SW2, and the frequency of the VCO14 can be further controlled in accordance with the key pressing speed.

FIG. 7 shows a pulse train generation circuit 1 that generates a pulse train whose frequency is constant and whose pulse width is periodically or randomly varied.
5 is a block circuit diagram showing a specific example of No. 3, and the same parts as in FIG. 5 are given the same reference numerals.

A comparator 24 outputs a high level only when the voltage A supplied to the other input terminal is higher than the voltage B supplied from the mixing circuit 16.

25 oscillates signals such as sawtooth waves, triangular waves, and sine waves,
It is a reference oscillator that supplies voltage A to comparator 24.

FIG. 8A is a waveform diagram showing input and output signal waveforms for explaining the operation of the comparator 24.

For example, the reference oscillator 25 supplies the comparator 24 with a sawtooth wave signal A as shown by the solid line in FIG. When the voltage is set to be lower than the peak voltage of the signal and supplied to the comparator 24 as voltage B, the comparator 24
A pulse train signal with a constant frequency is obtained as the output.

By changing the DC voltage using variable resistor VR4, the position of the comparison level is raised or lowered, the pulse width of the generated pulse train is varied, and the charging speed of capacitor C1 (FIG. 3) is adjusted.

Therefore, by turning on either select switch SW4 or SW2 or both switches at the same time, periodic
Aperiodic signal source 17 or Tatsuchireponse circuit 18
is connected to the mixing circuit 16, while the charging speed of the capacitor C1 is further changed periodically or non-periodically (randomly) by adjusting the variable resistor R4.
Alternatively, the charging voltage of the capacitor C1 can be increased depending on the key pressing speed.

For example, as shown by the broken line in FIG. A pulse train C whose pulse width periodically increases and decreases as shown in the figure is output.

According to the present invention, as described above, the modulation signal for imparting effects such as delay vibrato in electronic musical instruments can be set in a variety of shapes, and in particular, the amplitude of the rising portion of the modulation signal can be set to a variety of shapes. Since it can be temporally changed in a very complex manner, it is possible to impart various modulation effects that are audibly preferable.

The modulation signal from the modulation signal generator according to the present invention can be used in various effect control modulation circuits in electronic musical instruments, such as phase modulation circuits, amplitude modulation circuits, and timbre modulation circuits.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of an electronic musical instrument equipped with a conventional dayless vibrato effect device, FIG. 2 is a signal waveform diagram for explaining the operation of the electronic musical instrument of FIG. 1, and FIG. FIG. 4 is a block circuit diagram showing an embodiment of the present invention. FIG. 4 is a signal waveform diagram for explaining the operation of the embodiment of FIG. 3. FIG. 6 is a signal waveform diagram for explaining the operation of the pulse train generator of FIG. 5, and FIG. 7 is a block circuit diagram showing another specific example of the pulse train generator of the present invention. FIG. 8 is a signal waveform diagram for explaining the operation of the pulse train generator of FIG. 7. 7... Amplitude modulation circuit, 8... Modulation signal oscillator, 9... Differential circuit, 10... One shot multi, 11... Switching element, 12...Gate circuit, 13...Pulse train generator, 17...Periodic/non-periodic signal source, 18...Touch response circuit , 19...
...Oscillator, 20...Noise generator, C1.
・・・・・・Capacitor for voltage storage, KSl, KS2・
...Key switch.

Claims (1)

[Claims] 1 A modulation signal oscillator, an amplitude modulation circuit, a gate circuit, a capacitor to which a predetermined voltage is applied from a power supply via the gate circuit, and a pulse train that controls the gate of the gate circuit, with a pulse width or frequency set to a periodic period. A pulse train generator that generates a pulse train that changes randomly or randomly, and a means for clearing the charging voltage of the capacitor at the initial stage of a key press are provided, and the charging voltage of the capacitor is supplied to the amplitude modulation circuit and the modulation signal oscillator. A modulation signal generation device for an electronic musical instrument, characterized in that the modulation signal is generated by amplitude modulating an output signal.