JPS584147Y2 - Percussive envelope signal forming circuit for electronic musical instruments - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a percussive envelope signal forming circuit for adding a push effect to an electronic musical instrument.

The parka tumbu effect, which imparts a percussion sound effect to electronic musical instruments such as electronic organs, is produced by a variable amplification circuit that transmits a sound source signal from a sound source circuit 1 via an opening/closing circuit 2 that opens and closes by key operation, as shown in FIG. 3, the rectangular wave signal generated in response to the keystroke is formed into a desired percussive envelope signal by the percussive envelope signal forming circuit 4, and this signal controls the variable amplifier circuit 3 to generate the musical tone of the percussive envelope. A signal is obtained, amplified by an amplifier circuit 5, and output.

Here, as shown in FIG. 2, the conventional percussive envelope signal forming circuit 4 is composed of a switching element consisting of, for example, an NPN transistor TR, a resistor R, a capacitor C, and a variable resistor Rx for adjusting the sustain time. , the emitters of transistors TR are connected to a reference potential of -E.

Transistor TR is normally in an on state, and capacitor C is charged.

In response to the keystroke, a step-like human input signal vi as shown in a is applied to the input terminal, and the base potential of the transistor TR becomes H.
When the level drops from the level to the L level, the transistor TR turns off, and the charge stored in the capacitor C is discharged through the variable resistor Rx and the resistor R, and the discharge current i
Therefore, the output terminal receives an output signal V having a waveform like b.

appears and is used as the percussion envelope signal.

This output signal V.

When t is the time from the moment of keystroke, it is expressed as a function of time as shown in the following equation.

Therefore, by varying the variable resistor RX, the sustain time can be varied, but by changing the variable resistor RX, the initial amplitude value RX-E/R+Rx=E/R,+1
For example, the percussive envelope signal V in FIG.

If you try to lengthen the sustain time by increasing the variable resistance RXO value from the state obtained, V as shown by the dotted line.

′, the initial amplitude value also becomes large.

For this reason, changing the sustain time gives the impression that the volume has changed, making it impossible to freely vary only the sustain time.

This invention attempts to eliminate the above-mentioned drawbacks and provides a percussive envelope signal forming circuit in which only the sustain time of the percussive envelope signal can be arbitrarily varied.

Embodiments of this invention will be described below with reference to the accompanying drawings.

Figure 4 shows the basic configuration of this invention.
2 is the first reference potential (earth) and the second reference potential - the first and second switching elements connected in series between the E terminal, 6 is the inverter, and C and Rx are the same as in Figure 2. This is a capacitor and a variable resistor for adjusting the sustain time.

That is, the first and second switching elements Sl and 82
One end of the capacitor C is connected to the connection point of the capacitor C, and the other end of the capacitor C is connected to the ground which is the first reference potential via the variable resistor Rx, and the capacitor C and the variable resistor R
Output signal V from the connection point with X.

I'm trying to get it. In this circuit, normally the human input signal vj is at L level, the switching element S1 is off and the switching element S2 is on, and the capacitor C is charged by the circuit of the variable resistor RX and the switching element S2.
When the human input signal V becomes H level in response to a keystroke, switching element Sl is turned on, S2 is turned off, and the charge in capacitor C is transferred to switching element S1 and variable resistor R.
x, and the discharge current causes an output signal v0 as shown in the figure to appear at the output terminal.

As in the case of FIG. 2, this output signal is expressed by equation (2), where t is the time from the moment of keystroke.

Therefore, if the R factor is changed, the sustain time changes, but the initial amplitude value is always E and remains constant unless the value of E is changed.

In FIG. 4, when the value of variable resistor Rx is increased, the output signal becomes v5.

FIG. 5 shows a more specific embodiment of this invention, in which the switching element 51sS2 in FIG.
N-type transistor TR1 and PNP-type transistor TR2
The operation and effect are as explained with reference to FIG.

FIG. 6 shows an embodiment in which the on/off relationship of the switching elements is reversed from that in FIG. 5, and a PNP transistor TR1 is used as the switching element 81 vs2 in FIG.
and an NPN transistor TR2,
Normally, the transistor TR'1 is on, the TE10 is off, and the capacitor C is discharged. When the input signal Vi becomes H level in response to a keystroke, the transistor TR' is turned off, the TE10 is turned on, and the capacitor C is discharged. is variable resistance R
X, the light layer is applied via the transistor TR'2, and the output signal V is generated by its charging current j'.

' appears. This output signal has only the polarity reversed from that in FIG. 5, and the envelope is exactly the same.

Further, in any of the embodiments, the human input signal may be a signal that changes from H level to L level at the moment of keystroke, and in that case, the output signal is the same except that the polarity is reversed.

As described above, according to this invention, it is possible to obtain a desired par power tsunbu effect by arbitrarily varying only the sustain time of the bark knob sound.

[Brief explanation of drawings]

Figure 1 is a block diagram of a percussive effect circuit, Figure 2 is a circuit diagram of a conventional percussive envelope signal forming circuit,
Figure 3 is a diagram showing the relationship between sustain time and amplitude of a conventional percussive envelope signal, Figure 4 is a circuit diagram showing a basic embodiment of this invention, and Figures 5 and 6 are specific examples of this invention. This is a typical circuit diagram. 1...Sound source circuit, 2...Opening/closing circuit, 3
....variable amplification circuit, 5 ....amplification circuit,
4...Percup 7 envelope signal forming circuit, 6...Inverter, Sl sS2...
...Switching element, Rx...Variable resistor for adjusting sustain time.

Claims (1)

[Scope of utility model registration request] First and second switching elements connected in series are provided between a first reference potential and a second reference potential, and one end of a capacitor is connected to a connection point between the first and second switching elements. At the same time, the other end of the capacitor is connected to the first reference potential via a variable resistor, and the first and second
One of the switching elements is turned on and the other is turned off, and the on and off states of the first and second switching elements are reversed by pressing a key, and an output is output from the connection point between the capacitor and the variable resistor. A percussive envelope signal forming circuit for an electronic musical instrument that obtains a signal.