JPS5913663Y2 - Sustain gate circuit for electronic musical instruments - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a sustain gate circuit for an electronic musical instrument.

Conventionally, this type of circuit has been configured as shown in FIG. 1, for example.

That is, the collector of a transistor Tr whose base B is an input terminal for musical tone signals is connected to the negative pole -■ of a power supply via a diode D1, resistors R1 and R2, and a key switch K, its emitter is grounded, and the cathode of the diode D1 is A capacitor C is connected between the connection point A of the resistors R1 and R2 and the ground, and the connection point B between the resistor R2 and the key switch is connected to the sustain control circuit via the diode D2. When the key switch K is closed, a negative potential -■ is applied to the capacitor C via the resistor R2, charging it and at the same time, the resistor R
1 to the cathode of the diode D0, and by turning on the diode D1, a musical tone signal is output from the output terminal O.

At this time, the potential of the cathodes of the two diodes is equal to the charging potential of the capacitor C.

Next, when the key switch K is opened, the capacitor C is discharged from its charging potential via the resistor R2, the diode D2, and the sustain control circuit SC.

Therefore, as shown in the second diagram, the envelope characteristic gradually attenuates from the level H at which the key switch is kept ON, and sustain is obtained.

Thus, if the same key or another key is pressed immediately after a key is released, another musical tone will be generated before one musical tone is sufficiently attenuated, as shown in the third figure.

Therefore, the pronunciation of each musical tone becomes unclear, making it impossible to perform well.

The object of the present invention is to provide a sustaining gate circuit that improves the above drawbacks, and an embodiment shown in the drawings will be described.

In FIG. 4, reference numeral 1 denotes a three-terminal semiconductor element with a control pole 1a as an input terminal for musical tone signals.The semiconductor element 1 is composed of a transistor, and one end of the output pole, that is, the collector, is connected to a diode 2 and a resistor 3°. 4 and a key switch 5, one end of the power supply, that is, the negative electrode -■, was connected, and the emitter, which was the ground pole, was connected to the other end of the power supply, that is, the O electrode, which was the ground.

Then, an output terminal 6 is led out from the collector, a capacitor 7 and a parallel resistor 8 are connected between the connection point P of the resistors 3 and 4 and the ground, and a connection point between the resistor 4 and the key switch 5 is connected. X is connected to the sustain control circuit 10 via the diode 9, and the connection point X is connected to the resistor 11.
Connected to the collector.

The resistance value of resistor 11 is R1□, the resistance value of resistors 3 and 4 is R3,
When R4 is set, R5, R1,>R4 is established between these.

The sustain control circuit 10 includes a variable resistor 12 for attenuation adjustment and a switch 13 in parallel with the variable resistor 12.

Note that when the key switch 5 is closed, the diode 2 becomes reverse biased and acts so that the potential at point P does not appear at the collector of the transistor 1.

Thus, when the key switch 5 is closed, the capacitor 7 receives a voltage relatively lower than the power supply voltage due to the voltage division of the resistors 4 and 8.
■At the same time as being charged to 1, the potential at point X, that is, negative potential =
(2) is applied to the collector via the resistor 11.

Thus, the musical tone signal passes through the transistor 1, and a musical tone signal of level H1 corresponding to the negative potential -■ is obtained at the output terminal 6, as shown in FIG.

Next, when the key switch 5 is opened, the charged potential -Vl of the capacitor 7 is applied to the collector through the resistor 3 and the diode 2, and the level of the musical tone signal rapidly drops from Hl to R2 corresponding to -V1.

Then, attenuation according to the settings of the sustain control circuit 10 is obtained from the lowered level H2.

In this way, the level of the musical tone signal changes from Hl to R immediately after the key is released.
2, so even if the key is pressed subsequently, the musical tone will have a clear break as shown in Figure 6.

Incidentally, the rate of change from H1 to R2 is appropriately given by setting the resistance values of the voltage dividing resistors 4 and 8.

If the resistance value of the resistor 8 is small, discharge will occur immediately through the resistor 8 when the key switch is opened, so it is necessary to increase the resistance value to some extent.

However, since the voltage of R2 in FIG. 5 is obtained by dividing the voltage between resistors 8 and 4, resistor 4 must also be made larger.

If resistance 4 becomes too large, the sustain control will no longer work.

Therefore, it is troublesome to select an appropriate resistance value.

Therefore, instead of the resistor 8, a constant voltage diode 8' is used as shown in FIG.

In this case, the voltage across the Zener diode is always constant, so the resistor 4 can be chosen freely.

Also, no discharge occurs through the Zener diode.

According to the present invention, when the key switch 5 is closed, the capacitor 7 is charged with a voltage lower than the power supply voltage through the voltage dividing resistors 4 and 8, and the semiconductor element 1 is turned on with the power supply voltage through the resistor 11. Then, when the key switch 5 is subsequently opened, the semiconductor element 1 is charged at a low charging potential of the capacitor 7.
As a result, when the key switch 5 is opened, the level of the musical tone signal drops rapidly, followed by attenuation, so that even if the key is pressed immediately after the key is released, there is no gain due to the pressure of each weight. This has the effect of making it possible to clearly distinguish the musical tones that are played, and to be able to perform crisply and excellently.

[Brief explanation of the drawing]

Figure 1 is a conventional sustain circuit diagram, Figure 2 is its output characteristic diagram, Figure 3 is a musical tone envelope characteristic diagram when keys are pressed continuously, and Figure 4 is an example of the implementation of the present invention. circuit diagram,
FIG. 5 is a diagram of its output characteristics, FIG. 6 is a diagram of envelope characteristics of musical tones when keys are pressed continuously, and FIG. 7 is a circuit diagram of another embodiment. 1...3-terminal semiconductor element, 1a...control pole, 2゜9...diode, 3. 4. 8
．． 11... Resistor, 5... Key switch, 6... Output terminal, 7... Condenser, 10... Sustain control circuit.

Claims (1)

[Scope of utility model registration request] The control pole of a three-terminal semiconductor device consisting of control, output, and ground terminals is the input terminal for musical tone signals, and the output pole of the three-terminal semiconductor device is connected to a power source through a series resistance of two diodes and a key switch. A ground pole is connected to the other end of the power supply, an output terminal is led out from the output pole of the three-terminal semiconductor element, and a connection point between the two series resistors and the other end of the power supply are connected. A capacitor is connected to a resistor or a constant voltage diode in parallel to the capacitor, and a connection point between the key switch and the connected resistor is connected to a sustain control circuit via the diode, and the connection point is connected to the sustain control circuit via the resistor. A sustain gate circuit for an electronic musical instrument connected to an output pole of the three-terminal semiconductor element.