JPS5837104Y2 - Tone modulation signal generator for electronic musical instruments - Google Patents

Description

[Detailed description of the invention] This invention relates to an improvement of a signal generator for supplying a musical tone modulation signal with variable modulation speed to the musical tone signal modulation section of an electronic musical instrument, and in particular, the invention relates to the improvement of a signal generator for supplying a musical tone modulation signal with a variable modulation speed to the musical tone signal modulation section of an electronic musical instrument. By preventing this from occurring, it is possible to produce a modulation effect without any unnaturalness.

Conventionally, in electronic musical instruments, a musical tone signal is amplitude modulated or angle modulated (phase modulation or frequency modulation) according to a modulation signal consisting of an appropriate low frequency signal to obtain so-called tremolo effect, chorus effect, unsampling effect, etc. It is known to gradually change the oscillation frequency of a modulation oscillator when adding an effect (for example, Japanese Patent Laid-Open No. 52-3
(See Publication No. 420).

The reason why the frequency of the modulation signal is changed gradually in this manner is to prevent an unnatural modulation effect that is undesirable to the hearing sense from occurring due to a sudden change in the modulation speed.

By the way, as a musical tone signal modulation circuit of this type that has been proposed in the past, there is one shown in FIG.

In FIG. 1, MD is a modulator that manually modulates the musical tone signal IN, and this modulator MD includes a modulation oscillator O3.
A modulation signal M is supplied from a musical tone modulation signal generator including C.

The oscillator O3C is composed of a voltage controlled variable frequency oscillator ■CO, etc., and a switching device S is connected to its control input terminal.

, an oscillation frequency control signal (2) having a waveform as shown in FIG. 2 from a control voltage generation circuit including a resistor R8, a capacitor C8, and a buffer amplifier BF.

is supplied. In FIG. 2, the horizontal axis represents time t, and the vertical axis represents voltage ■.

Oscillator O3C receives control signal V.

When the value becomes ■1, the control signal ■ oscillates at a frequency (several tenths of Hz) at or near zero.

When it has a value of ■2, it oscillates at a frequency of several Hz to 10-odd Hz.

Switching device S. By appropriately switching between the power source with a voltage value of ■1 and the power source with a voltage value of ■2, an exponential function with a time constant of R8-Co is created between the ■level and ■level 2, as shown in Figure 2. A voltage change is obtained, and the oscillation frequency of the modulation oscillator O3C, and thus the modulation speed, change in accordance with such voltage change.

However, in the conventional musical tone modulation signal generator described above, when the modulation speed decreases (the control voltage or oscillation frequency decreases), the CoRo time constant curve is used, so the vicinity of the start of the fall is the vicinity of the end of the fall. This causes a rapid deceleration immediately after the start of the decrease, resulting in an unnatural modulation effect that is undesirable to the auditory sense.

In other words, at the beginning of the control voltage rise (a minute period after time t1 in Figure 2), the modulation frequency is near zero, and even if the control voltage change rate is large, it does not cause any audible problem, but when the control voltage falls In the initial stage (the very short period after time t2 in Figure 2), the modulation frequency is between a few and a dozen, so it turns out that if the rate of change in the control voltage is large, it has a considerable effect on the auditory sense. did.

Therefore, it is an object of this invention to provide a new musical tone modulation signal generator that eliminates the drawbacks of the prior art described above.

This idea is distantly related to the above-mentioned purpose, and involves supplying a constant current to a capacitor at least for a certain period of time immediately after the terminal voltage begins to decrease, producing a gradual, almost linear voltage change, and responding to this voltage change. The present invention is characterized in that the modulation speed is controlled to reduce the modulation speed.Hereinafter, an embodiment shown in the accompanying drawings will be described in detail.

FIG. 3 shows a musical tone signal modulation circuit according to an embodiment of the invention, in which the same parts as in FIG. 1 are denoted by the same reference numerals.

The circuit of this embodiment is characterized by constant current source (1)
．． Control signal ■ by controlling charging and discharging of capacitor C8 with ■2.

The key point is that a signal indicating a gradual linear voltage change is extracted.

Switching device S.

, the movable contact p is connected to the + This generates switching signals as shown in FIGS. 4a and 4f.

The switching signal a generated at time t1 when the movable contact p is brought into contact with the fixed contact q is converted into a pulse signal as shown in FIG. Set RF1.

When the flip-flop RF1 is set, its output signal C becomes a high level as shown in FIG. 4C, and the gate G1 is controlled to open in accordance with this signal C.

Therefore, the capacitor C8, which was initially at the ground potential V1, will be charged with a constant current 1, and its terminal voltage d will gradually increase with a linear slope of R(I,) as shown in Figure 4d. Rise.

At this time, the change in the terminal voltage d is detected by the comparator CM1. It is transmitted to CM2.

Comparator CM1. Each reference voltage of CM2 is set to V2゜■ in advance.
The buffer output ■ is set to a value of 1 and corresponds to the capacitor terminal voltage d.

Comparator CM1 generates a coincidence signal at time t1' when 2 becomes equal to 2.

This coincidence signal is converted by the one-shot circuit O33 into a pulse signal as shown in FIG. 4e, and this pulse signal e resets the flip-flop RF1.

Therefore, the flip-flop returns to a low level and gate G1 is controlled to close.

Therefore, the capacitor C after time t1'.

The terminal voltage of is maintained at a value of 2 as shown in FIG. 4d.

Next, when the movable contact p is brought into contact with the fixed contact r at time t2, the switching signal f becomes high level, and the signal f at this time is converted into a pulse signal as shown in Fig. 4g by the one-shot circuit OS2. be done.

Since this pulse signal g sets the R-S flip-flop RF2, the gate G2 is controlled to open by the output signal h (h in FIG. 4) of this flip-flop RF2.

Therefore, capacitor C.

is reversely charged (discharged) at a constant current ■2 after time t2, and the terminal voltage d becomes F(I2) as shown in Figure 4d.
It descends gently at a straight line gradient.

Changes in the terminal voltage d at this time are also transmitted to the comparators CM1 and CM2 via the buffer amplifier BF.

Buffer output ■ at time t2.

When becomes equal to 1, the coincidence signal from the comparator CM1 is converted by the one-shot circuit OS4 into a pulse signal as shown in FIG. 4g.

This pulse signal i resets the flip-flop RF2, so the output signal becomes low level and the gate G2
is controlled to close.

Therefore, capacitor C.

The terminal voltage is maintained at a value of 1 after time t2'.

As described above, according to the circuit arrangement of FIG. 3, the signal ① for controlling the modulation oscillator OSC.

As a result, a signal with a waveform that gradually rises and falls linearly can be obtained as shown in FIG. 4d.

As a result, in the modulator MD, the musical tone signal modulation speed changes gently not only during modulation acceleration but also during modulation deceleration, thereby making it possible to obtain a modulation effect rich in naturalness that is pleasing to the ears.

In the circuit shown in FIG. 3, as the modulator MD, various known amplitude modulators, phase modulators, frequency modulators, etc. can be used.

Also, capacitor C.

The charging and discharging by the constant current sources 11 and I2 is performed using constant current sources (1) instead of the method using the gate described above. (2) It is also possible to adopt the method of controlling the power supply, etc. in 2.

FIG. 5 shows a musical tone modulation signal generator according to another embodiment of this invention.
M3. A window comparator circuit including CM4 and AND gate AG3 is provided, and AND gate AG1
．． AG2, constant current source I3. I4, and gate G3. G4
By adding a charge/discharge control circuit including a charge/discharge control circuit, the change in the terminal voltage of the capacitor C8 becomes more complicated as shown in FIG.

Comparator CM3. The reference voltage of CM4 is set in advance as ■1<■3.
Since it is specified to satisfy the relationship <V4<V2, the buffer output ■.

is V3<V. <V4, the output of AND gate AG3 becomes high level.

Therefore, the output voltage ■. When is in the rising process, AND
When the output of gate AG3 becomes high level, the AND gate
) Since the output of AGl becomes high level, capacitor C8 is additionally charged with constant current 3 via gate G3.

Therefore, as shown in FIG. 6, the voltage increase curve is as follows: charging gradient R,1, due to constant current ■1, constant current ■1 and ■3
The charge gradient R2 (Il & I3) is expressed by the charge gradient R2 (Il & I3), and the charge gradient R3■1 is determined by the constant current ■1.

Similarly, the output voltage■.

■ Buffer output when is in the falling process.

When the voltage becomes less than 4 and the output of AND gate AG3 becomes high level, the output of AND gate AG becomes high level, so capacitor Co performs additional reverse charging (additional discharge) with constant current I4 via gate G4. ), and the voltage drop curve has a slope F, (I, , ), F 2 (
I 2 & I 4), and F 3 (I 2).

In short, depending on the circuit arrangement shown in FIG. 5, V3<V.

In the voltage range <V4, the charging/discharging speed of the capacitor C8 becomes faster, and as a result, the control signal ■ as shown in FIG.

The waveform of will begin to show a polygonal change.

Control signal ■ in Figure 6. It is clear that if the modulation oscillator is controlled by the above-described method, the same effects as those described above can be obtained.

More charging/discharging control means as explained with reference to FIGS. 5 and 6 can be provided based on the same principle, and in this case, the control signal V.

It is possible to obtain a waveform that exhibits smoother changes, which is advantageous in enhancing the naturalness of the modulation effect.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional musical tone signal modulation circuit, and FIG. 2 is an oscillation frequency control signal ■ in the circuit of FIG. 3 is a circuit diagram of a musical tone signal modulation circuit equipped with a musical tone modulation signal generator according to an embodiment of the invention, and FIG. 4 is a diagram showing various parts for explaining the operation of the circuit of FIG. 3. FIG. 5 is a circuit diagram of a musical tone modulation signal generator according to another embodiment of the invention, and FIG. 6 is an oscillation frequency control signal (2) in the circuit of FIG. FIG. MD...Modulator, O20...
...Modulation oscillator, Co...Condenser, ■1 to I4... Constant current source, BF...
Buffer amplifier, So... switching device.

Claims (1)

[Scope of utility model registration request] A capacitor, and the terminal voltage of this capacitor is set to a predetermined 2
A charge/discharge control circuit that controls charging and discharging of the capacitor so as to vary between levels, and a low frequency oscillator whose oscillation frequency is controlled in accordance with a control signal that shows a waveform change corresponding to a change in the terminal voltage of the capacitor. In preparation, the charge/discharge control circuit is provided with constant current source means for supplying a constant current to the capacitor at least during a certain period immediately after the terminal voltage of the capacitor starts decreasing, and the low frequency signal from the low frequency oscillator is modulated into a musical tone. A musical tone modulation signal generator for an electronic musical instrument configured to output as a signal.