JPS5913667Y2 - Musical tone signal generation circuit - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a musical tone signal generation circuit for an electronic musical instrument.

Conventionally, in an electronic musical instrument, a circuit for obtaining a musical tone signal having an envelope chops the output signal of an envelope signal generator EC as shown in FIG. There was a device that obtains an output musical tone signal with an envelope from the circuit, but as shown in Figure 2 (2-1), the output musical tone signal obtained by such a circuit changes the tone only by changing the volume with the passage of time. did not change, and the only musical sound signal that could be obtained was a monotonous musical instrument sound.

Therefore, this invention changes the timbre according to the change in volume.
This was done for the purpose of obtaining a musical tone signal suitable for the sound of a musical instrument.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a circuit diagram of a musical tone signal generation circuit showing an embodiment of the present invention.

The scale signal manually input from input terminal 1 is applied to the gate, which is the control terminal of FET-Ql, and the output envelope signal of envelope signal generator EG is applied to FET-Q2.
is applied to the gate, which is the control terminal of the

Here, the capacitor C2 is the FET which the output envelope signal of the envelope signal generator EG turns on and off according to the scale signal inputted from the input terminal (2).
- It is provided to remove the spike that occurs when being chopped by Ql, and is similar to capacitor C in Figure 1.
It plays the same role.

To explain the spike based on FIG. 2, 2-
The part A in Figure 2 is called a spike, and in a state where such a spike occurs, noise caused by the scale signal leaks from the output terminal O even when there is no output signal from the envelope signal generator EG. This can lead to undesirable results such as

Therefore, the capacitors C1C2 both serve to absorb and remove the spikes.

The envelope signal generator EG generates an envelope signal as shown in FIG. 4, for example, and the envelope signal is chopped by a FET-Ql that is turned on and off according to the scale signal input to the input terminal ■, and outputted as a musical tone signal to the output terminal O.
It is output from

At this time, FET Q2 is controlled by the envelope signal, and is in a cutoff state because a large negative voltage is applied to the gate at the C portion of the envelope signal.

Therefore, the input signal waveform at point B is 5-1 in Figure 5.
The waveform will be like this.

Note that since the resistor R has a high resistance, it hardly affects the waveform when the FET-Q2 is in the cutoff state.

Then, as the amplitude of the envelope gradually decreases, the negative voltage applied to the gate of FET-Q2 decreases, and the impedance between the drain and source decreases accordingly. As the constant becomes smaller, the input signal waveform 5-1 becomes 5-
The waveform has rounded edges as shown in 2.

Therefore, as shown in FIG. 6, the musical tone signal output from the output terminal O contains many harmonic components at the rise of the envelope, and as the amplitude of the envelope decreases, the harmonic components are removed.

As described above, the present invention provides a musical tone signal generating circuit that is highly useful and has a wide variety of musical tones for electronic musical instruments, whose tone color changes according to changes in volume.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional musical tone signal generation circuit. FIG. 2 is an output waveform diagram of the musical tone signal generation circuit of FIG. 1. FIG. 3 is a circuit diagram of an embodiment of the present invention. FIG. 4 is an output waveform diagram of the envelope signal generator EG. FIG. 5 is a waveform diagram at point B in the circuit of FIG. FIG. 6 is an output waveform diagram of the circuit of FIG. 3. EG...Envelope signal generator, C9C1, C2.
... Capacitor, ■ ... Input terminal, O.
...Output terminal, Q, Q construction, Q2...F
ET, R...Resistance, B...Point in the circuit.

Claims (1)

[Scope of utility model registration request] an envelope signal generator that generates an envelope signal; a switching element that has two poles at two points in the envelope signal path and chops the envelope signal by switching between the two poles where the envelope signal appears; and the switching element An integrating circuit is provided between the control I/roll terminal to which the control signal is applied and one of the above two poles, and the integrating circuit is constructed by connecting a capacitor and a variable impedance element in series. The envelope signal is applied to the control terminal of the variable impedance element to which the control signal is applied, and the scale signal is applied to the control terminal of the switching element, so that a change in volume is applied between the two poles of the switching element. A musical tone signal generation circuit characterized in that a musical tone signal whose tone color changes accordingly is obtained.