JPS589956B2 - Synchronous control signal generation circuit in electronic musical instruments - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In order to appropriately change the envelope, amplitude or frequency modulation degree, timbre, etc. of the musical tone signal output from the key switch circuit, the present invention can be controlled at the same time as the musical tone signal is supplied from the key switch circuit. The present invention relates to a synchronous control signal generation circuit in an electronic musical instrument that generates signals.

Conventionally, this type of circuit integrates and then differentiates a musical tone signal output from a key switch circuit to obtain a control signal.
This was supplied to various musical tone signal control circuits.

However, in this conventional circuit, it is necessary to increase the time constant of the integrator circuit to rectify the musical tone signal, but if this is increased, the rise of the output signal of the integrator circuit becomes gradual, and the output of the differentiator circuit is However, it has the drawbacks of being small and having poor responsiveness.

Further, in this conventional circuit, even when the number of musical tone signals output from the key switch circuit increases from one to two, etc., it is not possible to obtain a control signal of sufficient magnitude from the differentiating circuit.

SUMMARY OF THE INVENTION An object of the present invention is to provide a synchronous control signal generation circuit that can reliably obtain a large and responsive control signal in view of the above-mentioned conventional drawbacks.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 includes a sound source that generates a plurality of musical tone signals having semitone intervals from each other, and 2 includes a plurality of key switches that are linked to key operations and control the transmission of the corresponding musical tone signals. This is a key switch circuit, and the output terminals of the respective key switches are commonly connected.

3, 4.5 are tone circuits, each input terminal is connected in common and connected to the output terminal of the key switch circuit 2, and each output terminal is connected in common after passing through a variable resistor of 6°7.8. ing.

Reference numeral 9 denotes a musical tone signal control circuit having a gate function, the input terminal of which is connected to the common output terminal of the variable resistors 6, 7, and 8, and the output terminal connected to the speaker 11 via the main amplifier 10.
It is connected to the.

12 is a synchronous control signal generation circuit whose input terminal is connected to the output terminal of the key switch circuit 2 and whose output terminal is connected to the gate terminal of the musical tone signal control circuit 9; At the same time as receiving the supply, a control signal is output to the gate terminal of the musical tone signal control circuit 9.

Reference numeral 13 denotes an amplifier whose input terminal is connected to the output terminal of the key switch circuit 2, and whose output terminal is connected to each input terminal of the phase circuit 14 and the clamp circuit 15.

16 is a differential amplifier whose first input terminal 17 is connected to the output terminal of the phase circuit 14, second input terminal 18 is connected to the output terminal of the clamp circuit 15, and its output terminal is connected to the amplifier 19 and the Schmitt circuit 20. is connected in series to the gate terminal of the musical tone signal control circuit 9.

As shown in FIG. 2, the clamp circuit 15 has two capacitors 21 and 22 connected in series between its input terminal and output terminal, and the common connection point of both capacitors 21 and 22 is connected to the ground. It has a well-known configuration in which a diode 23 and a resistor 24 are connected in parallel between them.

In the above configuration, the circuit operation thereof will be explained next with reference to FIG. 3.

In addition, FIG. 3A shows the signal waveform at the output terminal of the phase circuit 14 (this point is set as 0 point), and FIG.

The signal waveform at the common connection point of the two capacitors 21 and 22 in the lamp circuit 15 (this point is defined as 0 point) is shown in Figure C, and the signal waveform at the output terminal of the clamp circuit 15 (this point is defined as 0 point).
The figure shows the signal waveform at the output terminal of the differential amplifier 16 (this point is designated as point 2).

When neither key switch is closed, no musical tone signal is output from the key switch circuit 2, and the voltages at the 0 point and 0 point are set in advance as shown between times TO and TI in FIG. 3A and C. The set mutually equal voltages EO are maintained.

Therefore, no output voltage is generated at point ■ as shown between time To and T1 in the third diagram.

Incidentally, the voltage at the zero point at this time is as shown between time To and T1 in FIG. 3C.

In the above state, if only one arbitrary key switch is now closed, the musical tone signal corresponding to that key switch is supplied from the tone source 1 to the musical tone signal control circuit 9 via the tone circuits 3 and 4. Ru.

On the other hand, the musical tone signal output from the key switch circuit 2 is supplied to a phase circuit 14 and a clamp circuit 15 via an amplifier 13 in a synchronous control signal generation circuit 12.

Therefore, at point 0, as shown between times Tl and T2 in FIG. 3A, a waveform is generated in which the phase of the rectangular musical tone signal output from the sound source 1 is delayed by a very small amount.

Also, the 0 point is at time T1 in FIG. 3B. As shown between T2, a waveform is generated by clamping the waveform generated at the 0 point using the threshold voltage of the diode 23 as the clamp voltage E1.

The voltage waveform of this 0 point waveform is the waveform of the 0 point plus a DC voltage, and when this waveform passes through the capacitor 22, the 0 point has a differential waveform of the DC voltage added to the waveform of the 0 point. The waveform shown between times TI and T2 in FIG.

The phase of the waveform generated at this zero point is delayed by the capacitors 21 and 22 in the clamp circuit 15 with respect to the tone signal output from the tone source 1, and this delay time is equal to that of the phase circuit 14.

Therefore, point ■ is at time T1 in the third diagram. As shown between T2, a waveform is generated by subtracting the voltage at the 0 point from the voltage at the 0 point, and after this waveform is amplified by the amplifier 19, it is shaped into a trigger pulse shape by the Schmitt circuit 20 and then sent to the musical tone signal control circuit. It is output to the gate terminal of 9.

This musical tone signal control circuit 9 is normally in a cut-off state, becomes conductive when receiving the trigger pulse, and operates as a gate so that the conductive state is gradually reduced by a time constant circuit included therein. It is.

The musical tone signal outputted from the tone color circuit 3°4.5 is converted into a percussion envelope waveform by the musical tone signal control circuit 9, and is emitted from the speaker 11 via the main amplifier 10.

Next, when one more key switch is closed while the one key switch is closed, the musical tone signals corresponding to those key switches are supplied to the musical tone signal control circuit 9 as described above. be done.

On the other hand, the musical tone signals outputted from the two key switches have a staircase waveform in which both of the musical tone signals are added to the 0 point in the synchronous control signal generation circuit 12, as shown after time T2 in FIG. 3A. appears as.

In addition, as shown after time T2 in FIG. 3B, the 0 point is 0.
A waveform in which the waveform at the point is clamped by the clamp voltage E1 of the clamp circuit 15 is generated.

This waveform at the 0 point is obtained by adding a DC voltage to the waveform at the 0 point.

This DC voltage is larger than the DC voltage of the waveform between times TI and T2 in FIG. The waveform shown after the added time T2 in FIG. 3C is generated.

Therefore, as shown after time T2 in the third diagram, the 0 point is
A waveform is generated by subtracting the voltage at the 0 point from the voltage at the 0 point, and based on this waveform, a trigger pulse-shaped control signal is output to the gate terminal of the musical tone signal control circuit 9 as described above.
In this musical tone signal control circuit 9, the musical tone signal is again converted into a percussion envelope waveform, and the sound is emitted from the speaker 11 via the main amplifier 10.

As mentioned above, in this embodiment, a differential amplifier 16 is used, a musical tone signal is inputted to its first input terminal via the phase circuit 14, and a capacitor is connected in the output circuit to its second input terminal. Since the musical tone signal is inputted through the clamp circuit 15 connected in series and the musical tone signal is simply processed digitally to obtain the control signal, the musical tone signal is not rectified by an integrating circuit as in the conventional method. The response is extremely good compared to what was obtained, and even when only one musical tone signal is output,
Even when the number increases from one to two, etc., a large control signal can be reliably obtained.

In this embodiment, a phase circuit 14 is provided to delay the output of the phase circuit 1.4 by the same amount as the delay time of the musical tone signal in the clamp circuit 15, and Although the tone signals input to the input terminals are in phase, the phase circuit 14 is not necessarily required if the delay time of the clamp circuit 15 is not small.

Further, in this embodiment, the Schmitt circuit 20 performs waveform shaping of the control signal, but this is not necessarily necessary.

Furthermore, in this embodiment, the case where the musical tone signal control circuit 9 is applied to obtain a percussion envelope has been described. It can be widely applied to delay tremolo or delay vibrato, or variable tone circuits that gradually change frequency characteristics from the time the key switch is closed.

As described in detail above, the synchronous control signal generation circuit in the electronic musical instrument of the present invention is capable of reliably obtaining a control signal that is extremely responsive and has a sufficient signal level in synchronization with the closing of a key switch. , the effect is great.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an electronic book illustrating an embodiment of the present invention;
FIG. 2 is an electronic circuit diagram showing a specific example of a part of the circuit, and FIGS. 3A to 3A are waveform diagrams of each part thereof. In the figure, 1 is a sound source, 2 is a key switch circuit, 9 is a musical tone signal control circuit, 11 is a speaker, 12 is a synchronous control signal generation circuit, 14 is a phase circuit, 15 is a clamp circuit, 16 is a differential amplifier, and 17 is a A first input terminal, 18 is a second input terminal, and 20 is a Schmitt circuit.

Claims (1)

[Claims] 1. A key switch circuit including a sound source that generates a plurality of musical tone signals, a plurality of key switches that are linked to key operations and control the transmission of the corresponding musical tone signals, and from the key switch circuit. a synchronous control signal generation circuit that generates a control signal at the same time it receives a musical tone signal; and a synchronous control signal generation circuit that generates an envelope, amplitude or frequency modulation degree, timbre, etc. of the musical tone signal output from the key switch circuit from the synchronous control signal generation circuit. In an electronic musical instrument comprising a musical tone signal control circuit that changes the musical tone signal as appropriate using a control signal, and a speaker that acoustically converts the musical tone signal from the musical tone signal control circuit, the synchronous control signal generating circuit has an operational amplifier as a main element, A musical tone signal from the key switch circuit is inputted to a first input terminal of the operating amplifier, and the musical tone signal is inputted to a second input terminal via a clamp circuit having a capacitor in series in the output side circuit. A synchronous control signal generation circuit for an electronic musical instrument, characterized in that: 2. The synchronous control signal generation circuit for an electronic musical instrument according to claim 1, wherein a musical tone signal is inputted to the first input terminal of the operational amplifier via a phase circuit. 3. The synchronization control signal generation circuit for an electronic musical instrument according to claim 1, wherein the output of the operational amplifier is supplied to the musical tone signal control circuit via a Schmitt circuit.