JPS58222Y2 - Vibrato device for electronic musical instruments - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a vibrato device for an electronic musical instrument that prevents problems such as pitch fluctuations particularly during non-vibrato.

In electronic musical instruments, as keys are operated, a sound source signal corresponding to the operated key and pitch is derived, and the derived sound source signal is appropriately shaped into a tone using a filter circuit, etc., to become a musical tone signal, and then output to a speaker. It is configured so that it is produced as a performance sound.

That is, the timbre of the performance sound is set using a filter circuit, but at the same time, effects such as vibrato are added to improve the performance effect.

In other words, this vibrato effect converts the sound source signal to 20Hz.
When adding a vibrato effect, a vibrato oscillator is driven and the oscillation signal is supplied as a modulation signal to a frequency modulation means for a sound source signal. It is.

All of the sound source signals generated in response to key operations are frequency-modulated by the vibrato modulation signal, thereby expressing a vibrato effect in which the pitch changes periodically in the performance sound.

However, when examining the state of expression of the vibrato effect in natural instruments, especially stringed instruments such as violins, we find that the vibrato effect is not added at the beginning of the instrument's rise, and that the vibrato effect gradually deepens after a short period of time has passed since the start of the instrument. The vibrato effect is additionally expressed as follows.

On the other hand, with the vibrato devices of electronic musical instruments such as those mentioned above, the vibrato effect is added from the beginning of the musical tone, and the vibrato is not sufficiently expressed for the performance effect, resulting in unnatural sound. becomes.

As a means to improve such drawbacks, it has been considered to perform vibrato modulation such that no vibrato effect is added at the rise of a musical tone, but gradually become deeper after a predetermined period of time has elapsed from the rise.

That is, the oscillation operation of the vibrato oscillation circuit is controlled so that the amplitude envelope of the vibrato modulation signal supplied to the frequency modulation means for the sound source signal is matched to the addition state of the vibrato effect.

Such a vibrato effect is particularly called delay vibrato.

FIG. 1 shows an example of a vibrato oscillation circuit for performing such vibrato modulation of performance sounds, and this oscillation circuit consists of a pair of transistors Tr1. It is composed of a multivibrator circuit using Tr2.

This oscillation circuit is oscillated and controlled by a bias voltage +V, and a rectangular waveform oscillation output signal having an amplitude and frequency corresponding to +■ is obtained from an output terminal connected to the collector circuit of the transistor Tr2.

That is, when adding a vibrato effect using such a vibrato oscillation circuit, its oscillation output signal is coupled to the frequency modulation means of the sound source circuit as a vibrato modulation signal.

The power supply voltage +■ is an envelope voltage corresponding to the amplitude of the vibrato signal to be obtained.

When such a vibrato oscillator is used, in a non-vibrato section immediately after the rise of a musical tone in which no vibrato modulation is performed, the voltage +■ is set to the ground potential, and the oscillation circuit is brought into a state where oscillation is stopped.

That is, during this non-vibrato period, no oscillation output signal is obtained from the output terminal.

However, even when the oscillation is stopped, the capacitors C1 and C2 that make up this multivibrator circuit
The residual charge affects the output, and the direct current component due to this residual charge is coupled to the frequency modulation means for the sound source signal, thereby affecting the sound source signal frequency.

In other words, when there is no vibrato, the pitch of the performance sound is distorted, which poses a serious problem to the stability of the electronic musical instrument player.

This invention was created in view of the above points, and aims to provide a vibrato device for electronic musical instruments that can reliably prevent adverse effects on the performance sound, especially when non-vibrato. The vibrato oscillation circuit is configured so that its output is cut off by grounding or the like.

An embodiment of this invention will be described below with reference to the drawings.

FIG. 2 shows its configuration, and a key press pulse signal in the form of a negative pulse is supplied to the input terminal 11 in response to a key press operation from a keyboard section (not shown).

The key press pulse signal from the input terminal 11 is transmitted to the transistor Tr3. Rectangular wave generation circuit 12 consisting of Tr4
is supplied as a rectangular wave generation command signal.

In this case, transistors Tr3. Tr4 is driven by a potential difference of +15V and -15V, and from this circuit 12, as shown in A of Fig. 3, the voltage rises from -15V to +15V with the key press pulse, and after time T, rises from +15V to -15V. A rectangular wave signal with a falling time width T is generated.

The rectangular wave signal generated from this rectangular wave generating circuit 12 is
Two diodes DI and D2 whose anodes are connected to each other are connected in series to the base of the transistor Tr5.

In this case, a +15V power supply is connected to the connection point between the anodes of diodes DI and D2 via a resistor R1, and when the potential on the square wave generation circuit 12 side is lower than +15V, that is, -15V, a power supply of +15V is connected to the connection point between the anodes of the diodes DI and D2. The +15V power supply from the resistor R1 is bypassed so that the base bias is not applied to the transistor Tr5.

Then, a square wave is generated, and the cathode side of diode D1 is +
When the voltage reaches 15V, a base bias is applied to the transistor Tr5 via the resistor R1 and the diode D2, and the collector and emitter of the transistor Tr5 are set to be conductive.

The transistor Tr5 has a common emitter type, and its collector is connected to +1 through resistors R2 and R3.
A 5V power supply is connected, and a capacitor C3 is connected between the resistor R3 and the ground point.

In other words, capacitor C3 is normally charged with +15V,
When a rectangular wave is generated, it is discharged to the ground potential via the transistor Tr5, and the diodes D1, D2 . The transistor Tr5 constitutes a discharge control circuit 13 for the capacitor C3.

Furthermore, after the discharge circuit by the transistor Tr5 is cut off, the capacitor C3 has a value equal to the value of the capacitor C3 and the resistor R.
The battery is charged to +15V with a time constant determined by a value of 3, and a time constant circuit 14 is set by a resistor R3 and a capacitor C3.

That is, the potential at point X of the capacitor C3 is always +15V as shown in B in FIG.
When a rectangular wave signal as shown in A in the figure is generated, it is discharged to the ground potential, and after the rectangular wave signal falls, it is charged to +15 V with a time constant determined by the time constant circuit 14 as time passes. Change.

The envelope signal shown in B in FIG. 3, which is extracted as a change in the terminal voltage of the capacitor C3, is supplied to the positive phase amplifier circuit 15 and the inverting amplifier circuit 16.

Then, the positive phase amplifier circuit 15 outputs an envelope signal similar to that shown in B of FIG. 3, and the inverting amplifier circuit 16 outputs the envelope signal as shown in C of FIG. Output the inverted envelope signal at the center.

In other words, 2 which is inverted around the reference potential (ground potential)
The absolute value of the potential corresponds to the potential at the terminal of the capacitor C3, that is, at the point X.

The potential signals from these two types of power supply circuits are supplied as driving signals to a vibrato oscillation circuit 17 consisting of an operational amplifier (op), resistors R4, R5, R6, and a capacitor C4. is driven by the potential difference between the two types of power supply circuits, and outputs an oscillation signal corresponding to charging and discharging of the capacitor C4.

(Note that the capacitor C4 corresponds to the capacitors C1 and C2 of the first multi-bifilter circuit.

) The oscillation signal from this vibrato oscillation circuit 17 is led to an output terminal 19 via a high input impedance buffer amplifier 18, from which a vibrato signal output for frequency modulating a sound source signal is obtained, for example.

Here, the vibrato oscillation circuit 17 is connected to B and C in FIG.
Since it is driven by the envelope voltage signal shown in Figure 4, the amplitude envelope of the vibrato signal is a composite of the envelopes B and C in Figure 3 centered around the ground potential G, as shown in Figure 4. The center of vibration of the vibrato signal is kept stably at the ground potential G.

That is, when the sound source signal is frequency-modulated with this vibrato signal, the basic pitch of the performance sound is stably maintained at a predetermined sound source pitch.

However, when vibrato modulation is performed in this manner, the vibrato oscillation circuit 17 is in a non-vibrato state for a time T from the generation of the key press pulse, and the vibrato oscillation circuit 17 is in a state where oscillation is stopped.

When the oscillation circuit 17 stops oscillating, the capacitor C constituting the oscillation circuit 17 is
There is a high possibility that the residual charge of 4 will appear at the output end and act to shift the pitch of the sound source signal.

Therefore, in this invention, a field effect transistor FET is further connected between the output side of the vibrato oscillation circuit 17 and the ground point.
A gate circuit 20 is provided.

The gate electrode of the transistor FET is connected to the output side of the rectangular wave generating circuit 12 via a diode D3, and is grounded via a resistor R7.

That is, when the rectangular wave output is being generated from the rectangular wave generating circuit 12, the gate electrode of the transistor FET is grounded via the resistor R7, and the source and drain of the transistor FET are in a conductive state.

When the rectangular wave signal does not exist, the gate electrode of the transistor FET is connected to -15 through the diode D3.
V, and the source and drain of this transistor FET are brought into a non-conducting state.

Looking at this in relation to the oscillation output from the vibrato oscillation circuit 17, the gate circuit 20 is closed during vibrato when the oscillation output is present, and the oscillation signal is transmitted to the high input impedance buffer amplifier 18.

On the other hand, during non-vibrato immediately after the rise of the chestnut tone, the gate of the gate circuit 20 is opened, the output side of the vibrato oscillation circuit 17 is bypassed to the ground point, and the human power of the high input impedance buffer amplifier 18 is accurately controlled. held at ground potential.

In other words, even if there is an output due to residual charge from the vibrato oscillation circuit during non-vibrato, this is reliably blocked and is not transmitted to the vibrato modulator, which can cause pitch deviations in the sound source signal, especially during non-vibrato. The occurrence of this can be reliably prevented, and the performance sound of the electronic musical instrument can be reliably stabilized.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a conventionally used vibrato oscillation circuit, FIG. 2 is a configuration diagram explaining a vibrato device according to an embodiment of this invention, and A to C in FIG. 3 are respectively the above embodiments. FIG. 4 is a signal waveform diagram illustrating the effect of . Similarly, FIG. 4 is a diagram showing the amplitude envelope of the vibrato signal. 11... Input terminal, 12... Rectangular wave generation circuit, 13... Discharge control circuit, 14...
... Time constant circuit, 15 ... Positive phase amplifier circuit, 16
...Inverting amplifier circuit, 17 ... Vibrato oscillation circuit, 18 ... High input impedance buffer amplifier, 19 ... Output terminal, 20 ...
...Gate circuit.

Claims (1)

[Scope of utility model registration request] means for setting a time width specified by a key press operation; a time constant circuit for generating an envelope signal that rises from a reference potential with a time constant after the time width set by the means; and an envelope signal generated by the time constant circuit. a vibrato oscillation circuit whose oscillation is controlled by an envelope signal and generates a signal with an amplitude corresponding to the potential difference from the reference potential; and a vibrato oscillation circuit provided in the output circuit of the vibrato oscillation circuit to take out the output signal from the oscillation circuit and control the cutoff. and a gate circuit, the gate circuit performs gate control in a reference potential state of the envelope signal of the specified time width, and controls to cut off the output signal from the oscillation circuit within the time width. Features a vibrato device for electronic musical instruments.