JPS5815987Y2 - Opening/closing circuit for electronic musical instruments - Google Patents

Description

[Detailed explanation of the idea] This invention relates to an opening/closing circuit for an electronic musical instrument.

In electronic musical instruments, the opening/closing circuit is used to pass only the signal corresponding to the pressed key, out of the sound source signals of various frequencies corresponding to the pitch of each weight, and is made up of gates such as field effect transistors. be done.

Conventionally, a predetermined DC voltage is usually applied to the gate in response to a key press, and this DC voltage is switched (on or off) depending on the phase of the sound source signal (whether its value is "l" or "0"). so that the sound source signal and one frequency,
And I was trying to get a signal with a predetermined busy width.

However, in the conventional system, when the sound source signal is in the "O" phase, the switching output is always at ground potential (0 potential), so the output signal is a pulsating current containing a direct current component.

Since it contains a direct current component, a means for blocking the direct current component is required, and the quality of the generated sound is poor.

This invention has been made in view of the above-mentioned points, and is intended to provide a switching circuit that can obtain a switching output that does not include a DC component.

According to this invention, DC voltages with different polarities are applied to the two gates, the two gates are turned on and off alternately depending on the phase of the sound source signal, and their outputs are flattened to match the sound source signal. They listen to the same frequency and obtain an output that does not include DC components.

This invention will be explained in detail below based on an embodiment of the accompanying drawings.

First, the mechanism by which musical tones are generated in an electronic musical instrument will be briefly explained using FIG.

In FIG. 1, a sound source circuit 1 is usually composed of an oscillator, a frequency divider, etc., and generates sound source signals P of various same wave numbers corresponding to each weight of a keyboard 2.

The switching circuit section 3 inputs the sound source signals of various frequencies mentioned above,
Of the sound source signal P, only the signal of the frequency corresponding to the pressed key is allowed to pass.

That is, this opening/closing circuit section 3 is a circuit that includes a gate such as a field effect transistor for each key, and individual sound source signals are guided to the husband's gate.

From the keyboard 2, a signal S indicating the suppression state of each individual key (“1” when pressed, “0” when not suppressed)
is output, and this signal is applied to each of the corresponding gates to turn them on and off.

In this way, the sound source signal of the frequency corresponding to the pressed key is guided from the opening/closing circuit section 3 to the output line t.

The timbre circuit 4 combines filters corresponding to appropriate timbres, forms the sound source signal output from the switching circuit section 3 into an appropriate timbre, and guides it to the lobby force 5.

As described above, the speaker 5 emits a musical tone having a desired tone color and a pitch corresponding to the pressed key.

In this invention, the switching circuit section 3 is constituted by a switching circuit 3a as shown in FIG. 2, for example.

The opening/closing circuit 3a shown in FIG. 2 corresponds to one key (key 1), and the actual opening/closing circuit 3 has a circuit similar to this opening/closing circuit 3a for the number of keys. only built in.

A series circuit 9 in which four gates 01 to G4 are connected in series is formed in this switching circuit 3a, and both ends thereof are connected between e and -e at different potentials.

The output line corresponding to the key Kl of the keyboard 2 is the gate Gl.
and G4 are connected to GlF; It is turned on when

When turned on, gates G1 and G4 are at the above voltage +e+
-e to gates G2 and G3, respectively.

The sound source signal Pi (shown in FIG. 3a) with a frequency corresponding to the pitch of key 1 output from the sound source circuit 1 is connected to the gate G.
2 and is also applied to gate G3 via inverter 6.

With this configuration, gates G2 and G3 are alternately turned on and off.

For example, when the sound source signal PIO value is "1", the gate G2 is turned on, and the positive voltage (shown in FIG. 3C) led from the power source 10 through the gate G1 is guided to the output line t1.

Further, when the sound source signal P1 is "O", the gate G3 is turned on, and the negative voltage (shown in FIG. 3d) led from the -0 power supply via the gate G4 is led to the output line t1.

Therefore, the line t1 has the same wave number as the applied sound source signal P0, and has an intermediate potential (ov in the embodiment shown in FIG. 2) of the voltages (e, -e) applied across the series circuit 90. ) is the center of the tracing motion (shown in FIG. 3e).

By the way, the point between the gates G□, 02 and the above intermediate potential point (
In other words, the time constant circuit 1 connected between
, and Goo) G3. The time constant circuit 8 connected between the point between G4 and the intermediate potential point is for obtaining a sustain effect.

In other words, when the key is released, if the output of the opening/closing circuit 3a falls instantly, the musical sound will be unnatural and an unpleasant sound will be generated. This slows down the decline.

The time constant circuits 7 and 8 are connected to resistors Bt and i of the same value.
and a capacitor C in parallel, and the time constants are set to the same value.

Therefore, the capacitors C of time constant circuits 1 and 8 are gross)
When Glt, T and G4 are turned on, they are charged, and when the signal s1 falls and the gates Glt6 and G4 are turned off, the charged charges are gradually discharged through the resistor R.

Therefore, a signal to which a sustain effect envelope is applied is output from the output line t1.

Now, the signal obtained from this opening/closing circuit 3a when, for example, the key is released from the state in which 1 is pressed will be explained.

Assume that the key is released at time t1 and the signal S1 falls to "O" as shown in FIG. 3.

This turns off gates GIF6 and G4.

Therefore, the charges stored in the time constant circuit T and the capacitor C of 8 begin to discharge through the resistor R, and the gate G
The voltages applied to G2 and G3 gradually decay as shown in FIGS. 3c and d, respectively.

Since the time constants of time constant circuits 7 and 80 have the same value as described above, they reach voltage O at the same time.

Therefore, the output signal obtained from line t becomes an attenuated signal to which a vertically symmetrical Nastin effect envelope is applied, as shown in FIG. 3e.

As explained above, according to this invention, different voltages are applied to each of the 12 gates, and the gates are turned on and off alternately depending on the phase of the sound source signal, so that the DC component can be opened and closed with little effort. This has the effect that an output signal can be obtained.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing the overall configuration of an electronic musical instrument to which this invention is applied, Fig. 2 is a circuit diagram showing an embodiment of the opening/closing circuit according to this invention, and Fig. 3 is a block diagram showing the overall configuration of an electronic musical instrument to which this invention is applied. FIG. 2 is an operation explanatory diagram illustrating the operation of the circuit shown in FIG. 2; 3a... Opening/closing circuit, 7, 8... Time constant circuit, 9... Goot series circuit, 01 to G4.
·····Gate.

Claims (1)

[Scope of utility model registration request] A series circuit comprising four first to fourth gates connected in series between different potentials; Time constants having the same time constant connected between the point between the second gates and the intermediate potential point of the different potentials, and between the point between the third and fourth gates and the intermediate potential point, respectively. circuit, and the second and third
The gates are turned on alternately according to the phase inversion of the sound source signal.
and a drive circuit that turns off the first and fourth gates when the key is pressed and turns on the second and third gates.
The output is taken from a common connection point of the gates, and when the key is released, the first and fourth gates are turned off to produce an output having an envelope corresponding to the attenuation characteristic of the signal output from the time constant circuit. An opening/closing circuit for an electronic musical instrument, characterized in that the circuit is extracted from the above-mentioned common connection point.