JPH0114075Y2 - - Google Patents

Description

[Detailed Description of the Invention] The envelope waveforms of the rising and falling edges of a musical tone in a natural musical instrument usually differ depending on the pitch, as shown in FIG. That is, the envelope waveform HE in the treble part has a steep rise and fall, and the waveform LE in the bass part has a gentle rise and fall.
On the other hand, with conventional electronic musical instruments, when controlling musical tone amplitude by obtaining an envelope signal waveform, the envelope signal waveform cannot change depending on the pitch.
Envelope signal forming circuit as shown in Figure 2
Voltage controlled amplifier VCA with simple waveform of EVP
It just controls. Therefore, the musical sound signal source
The musical tone signal output from the TG is only subject to monotonous control.

SUMMARY OF THE INVENTION An object of the present invention is to provide an envelope signal waveform forming circuit for an electronic musical instrument that improves the above-mentioned drawbacks and changes the envelope signal waveform depending on the pitch to obtain a musical tone closer to a natural musical instrument.

Embodiments of the present invention shown in the drawings will be described below. Figure 3 shows a block diagram of the case where the present invention is applied to a synthesizer.
The output is applied to a voltage-controlled oscillator VCO to obtain a musical tone signal, for example, a rectangular wave output, with a frequency that differs depending on the key depression position, and is applied to a voltage-controlled filter VCF and a pulse generator PSG. Pulse generation circuit
PSG is a pulse train whose pulse generation interval changes depending on the output of a voltage controlled oscillator VCO whose frequency varies depending on the pitch voltage and whose pulse width is constant.
In other words, it is a constant width pulse and is a voltage controlled oscillator.
Generates a number of pulses corresponding to the musical tone signal from the VCO. FIG. 4 is a specific circuit example of the generator circuit PSG and the envelope signal forming circuit EVP,
PKC is a key press signal conversion circuit, LGC is a logic operation circuit,
Tr1 and Tr2 are transistors connected in series, R
and C indicate the time constant circuit of the envelope signal forming circuit EVP. The key press signal conversion circuit PKC is a voltage controlled oscillator that rises when a key is pressed and produces the lowest sound.
The capacitor C of the EVP is controlled by the signal from the VCO.
For example, use a monostable multivibrator to generate a pulse width that can charge the battery. The pulse generator circuit PSG generates pulses with a constant pulse width but dense pulse intervals (large number of pulses) when the tone is high, and pulses with a constant pulse width but sparse pulse intervals (large number of pulses) when the tone is low. Pulse output (with a small number of pulses) can be obtained, and the AND operation circuit
Applied to LGC. Therefore, the transistor Tr1 repeats conduction and non-conduction based on the output of the key press signal conversion circuit PKC, but since the period of non-conduction is extremely short in the high-pitched range, the capacitor C is rapidly charged. Since the voltage across the capacitor C is an envelope signal waveform, a steep rising waveform of HES in FIG. 5 is obtained. Then, the voltage Vc at the time of completion of charging is maintained for a while, and discharging starts when the output pulse of PKC falls. In this case as well, since the discharge is almost continuous, a waveform with a sharp falling portion of HES in FIG. 5 is obtained.

On the other hand, in the case of a bass part, since the waveform occupation ratio of the output of the pulse generating circuit PSG is small, charging and discharging takes a longer time, and a gentle waveform as shown in FIG. 5 LES is obtained. The obtained envelope signal waveform is not smooth in both the treble and bass parts, but this is a waveform that controls the voltage-controlled amplifier VCA, and the musical tone signal period is shorter than the rise and fall times of the envelope signal waveform. Since it is much smaller, it causes almost no distortion.

Next, FIG. 6 shows a second embodiment in which the present invention is applied to an electronic organ, where the same symbols as in FIG. This circuit shows a switch controlled by a PKC output, and transistors Tr1 and Tr2 are not connected in series in this example circuit. The pulse generating circuit PSG generates pulses whose pulse width is constant but whose pulse intervals vary from dense to sparse according to the output frequency of the musical tone signal source TG, and generates pulses according to the high/low of the musical tone signal as shown in Fig. 4. Obtain the pulse waveform shown in the output of the generator circuit PSG. When the key press switch (not shown in Fig. 6) is operated and an output pulse of the key press signal conversion circuit PKC is generated, the switch SW
1 and set switch SW2 to open. Since the capacitor C is continuously charged, the output pulse width of the key press signal conversion circuit PKC is selected to be the time required for charging to be completed using the time constant RC. When charging is completed and the key press signal conversion circuit PKC falls, the switch SW
1 opens, switch SW2 closes, pulse generation circuit
The pulse output of PSG is the conduction of transistor Tr2.
The capacitor C is discharged by repeating non-conduction. Since the course of the discharge is similar to the falling waveform in FIG. 5, an envelope signal waveform HES that falls sharply in the high-pitched portion, and an envelope signal waveform LES that falls slowly in the bass portion are obtained.

In this way, according to the present invention, the envelope signal waveform that controls the voltage-controlled amplifier is changed depending on the treble and bass parts, and the envelope signal waveform is made gentler in the bass part than in the treble part. , even if it is an electronic musical instrument,
A musical tone signal closer to that of a natural musical instrument can be obtained, and the performance effect can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an envelope waveform in a natural musical instrument, FIG. 2 is a block diagram of the vicinity of the envelope signal forming circuit in a conventional electronic musical instrument, FIG. 3 is a block diagram showing the configuration of the first embodiment of the present invention, and FIG. 3 is a partial detailed view of FIG. 3, FIG. 5 is an explanatory diagram of the operation of FIG. 4, and FIG. 6 is a diagram showing the configuration of a second embodiment of the present invention. TG...musical tone signal source, VCA...voltage controlled amplifier, EVP...envelope signal forming circuit, THG
...Tone pitch voltage generation circuit, VCO...Voltage controlled oscillator, PSG...Pulse generation circuit, PKC...Key press signal conversion circuit, LGC...Logic AND operation circuit.

Claims (1)

[Claim for Utility Model Registration] A pitch voltage generation circuit THG that outputs a keystroke signal and a pitch signal of a voltage corresponding to the pressed key, and a musical tone signal of a frequency corresponding to the output signal of the pitch voltage generation circuit THG. A voltage-controlled oscillator that generates
VCO, and a voltage-controlled filter that shapes the tone and amplitude of the musical tone signal from the voltage-controlled oscillator VCO.
a VCF/voltage controlled amplifier VCA; an envelope signal generator that controls the voltage controlled filter VCF/voltage controlled amplifier VCA by a key press signal from the pitch voltage generating circuit THG; and the pitch voltage generator. a pulse generation circuit PSG that inputs a key press signal from the circuit THG and a musical tone signal from the voltage controlled oscillator VCO and controls the envelope signal generator, the envelope signal generator is configured to input a key press signal from the circuit THG and a musical tone signal from the voltage controlled oscillator VCO to control the envelope signal generator; It is composed of a capacitor C that is charged by a signal, a transistor and a resistor that control charging and discharging of the capacitor C, and the pulse generating circuit PSG generates a constant width pulse and generates a musical tone signal from the voltage controlled oscillator VCO. , the capacitor C is discharged by the output pulses of the pulse generating circuit PSG, and changes in charging and discharging of the capacitor C are used as an envelope signal waveform. envelope signal waveform forming circuit.