JPH0627950A - Acoustic signal generating circuit - Google Patents

Abstract

PURPOSE:To obtain a sound generating device of simple constitution which give depth and weight close to a natural sound to a timbre. CONSTITUTION:When a pulse is inputted to a terminal A to reset a signal generating circuit 2 and frequency dividers 12 and 13, the signal generating circuit 2 reads a frequency division ratio from a pitch control signal and sets it and a fundamental frequency generating circuit 1 generates a set pitch signal F1. A control circuit 11 puts switching circuits 5 and 6 in operation corresponding to the frequency of the pitch signal F1 to charge and discharge a capacitor 4 and an envelope signal containing a beat component is outputted to a multiplying circuit 20. The multiplying circuit 20 generates a sound signal composed of the pitch signal F1 and the envelope signal containing the beat component to output a sound from a speaker 22 through an amplifier 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic signal generating circuit.

[0002]

2. Description of the Related Art Conventionally, in order to electronically generate a sound closer to a natural sound, a beat signal is mixed by mixing a frequency signal corresponding to a desired pitch and a signal whose frequency is slightly deviated from the frequency signal. Ingredients were given.

[0003]

In the method of generating a beating tone by the above method, when a plurality of sounds having different pitches are to be selectively generated, a frequency is generated for each frequency signal of each sound. Had to generate a signal with a slight deviation, and the circuit configuration for that was complicated.

An object of the present invention is to provide a tone color with depth and solidness like natural sounds with a simple structure.

[0005]

According to the present invention, a control circuit for adjusting a beat component of an envelope signal including a beat component generated from a charge / discharge circuit according to a frequency of a frequency signal corresponding to a pitch of a sound, The above object is achieved by providing a synthesis circuit that synthesizes a frequency signal corresponding to the pitch of the sound and the envelope signal to generate an acoustic signal.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on an embodiment shown in the drawings.

In FIG. 1, reference numeral 1 is a basic frequency generating circuit, which comprises a crystal oscillator, a frequency divider, etc.
Generates ₀ . Reference numeral 2 denotes a signal generating circuit, which is composed of a variable frequency divider or the like, and appropriately divides the fundamental frequency signal F ₀ according to the input pitch control signal F to output a pitch signal F ₁ . A charging / discharging circuit 3 includes a capacitor 4, switching circuits 5, 6,
7 and resistors 8, 9, 10, etc., and an envelope signal including a beat component is generated from a terminal C. In this example, the resistance values of the resistors 8, 9 and 10 are set so that resistance 8> resistance 9> resistance 10. A control circuit 11 includes frequency dividers 12, 13, a flip-flop circuit 14, inverters 15, 16 and gate circuits 17, 18, 19
And controls the operations of the switching circuits 5 and 6 in accordance with the frequency of the pitch signal F ₁ .

The frequency divider 12 uses a two-stage flip-flop circuit in this example, and divides the fundamental frequency signal F ₀ into ¼. The frequency divider 13 uses a three-stage flip-flop circuit in this example, and divides the input signal into 1/8. Reference numeral 20 denotes a multiplication circuit that constitutes a synthesis circuit, and synthesizes the pitch signal F ₁ generated from the signal generation circuit 2 and the envelope signal output from the terminal C of the charge / discharge circuit 3 to generate an acoustic signal. 21
Is an amplifier and 22 is a sounding body, and a speaker is used in this example.

Next, the operation will be described with reference to FIG.

It is assumed that the fundamental frequency signal F ₀ is output from the fundamental frequency generating circuit 1 as shown in FIG.

Start pulse P is applied to terminal A as shown in FIG. 2A.
When 1 is input, the signal generation circuit 2, the frequency divider 12, and the frequency divider 13 are reset.

Then, the signal generation circuit 2 causes the pitch control signal F
Read the division ratio from and set it to the read division ratio.

In the present case, the frequency division ratio of the signal generating circuit 2 is 1
It is assumed that it is set to / 16.

Then, a pulse P is applied to the terminal B as shown in FIG. 2B.
When 2 is input, the switching circuit 7 is turned on, the capacitor 4 is rapidly charged via the resistor 10, and the potential of the terminal C becomes high as shown in FIG. 2C.

In this embodiment, an envelope signal containing a beat component is generated by changing the potential of the terminal C.

From the signal generating circuit 2, a pulse P3 is generated as a pitch signal by dividing the fundamental frequency signal F ₀ shown in FIG. 2F ₁ by 1/16.

The flip-flop circuit 14 is an inverter 1
When the output of 5 is "1", that is, F of the signal generating circuit 2
₁ Reset when the input signal is "0".

When the pulse P3 is generated from the signal generating circuit 2, the reset of the flip-flop circuit 14 is released,
Since the output becomes "1", the gate circuit 17 opens.

When the pulse P4 is generated from the frequency divider 12 as shown in FIG. 2F ₂ , the pulse P5 passes through the gate circuit 17 as shown in FIG. 2F ₃ .

Since the output from the frequency divider 13 is "0" as shown in FIG. 2F ₄ , the gate circuit 18 is closed, but the gate circuit 19 is opened by way of the inverter 16, and the pulse P5 is generated. Is a gate circuit 1 as shown in FIG. 2S6.
After passing through 9, the switching circuit 6 is turned on.

When the switching circuit 6 is turned on, the electric charge charged in the capacitor 4 is discharged through the resistor 9, and the potential of the terminal C becomes low as shown in FIG. 2C.

When the generation of the pulse P5 is completed, the switching circuit 6 is turned off, the discharge of the capacitor 4 is completed, and the potential of the terminal C is held at a constant value as shown in FIG. 2C.

Then, the flip-flop circuit 14 is triggered by the falling edge of the pulse P5, reads "1" from the D input terminal, and outputs "0" which is the inverted read input signal.

The output of the flip-flop circuit 14 is "0".
As a result, the gate circuit 17 is closed, and even if a pulse P6 is generated from the frequency divider 12, this pulse P6 cannot pass through the gate circuit 17, so that the switching circuits 5 and 13 are not turned on and the capacitor 4 is charged and discharged. I can't.

That is, the capacitor 4 is charged or discharged once for each pulse of the pitch signal generated from the signal generation circuit 2.

When the output of the pulse P3 is completed,
The flip-flop circuit 14 is reset, and its output becomes "1" again.

Next, when the pulses P7, P8, P9 are generated from the signal generating circuit 2 as shown in FIG. 2F ₁ , the same operation as described above is performed, and the potential at the terminal C is 1 pulse of the pitch signal as shown in FIG. 2C. It will gradually decrease as you do.

When the pulse P10 is generated from the gate circuit 17 as shown in FIG. 2F ₃ while the pulse P9 is generated from the signal generation circuit 2, the frequency divider 13 causes the frequency divider 13 to generate the pulse P1.
Triggered on the falling edge of 0, the output inverts from "0" to "1".

Then, when the pulse P11 is generated from the signal generating circuit 2 as shown in FIG. 2F ₁ , the pulse P12 passes through the gate circuit 17 in the same manner as described above.
Since the output of is 1 as shown in FIG. 2F ₄ , the gate circuit 18 is open, but the gate circuit 19 is closed through the inverter 16, and the pulse P12 passes through the gate circuit 18 and the switching circuit. Turn on 5.

When the switching circuit 5 is turned on, the capacitor 4 is charged through the resistor 8 and the potential at the terminal C becomes high as shown in FIG. 2C.

Thereafter, the same operation as described above is performed when the signal generating circuit 2 generates pulses P13, 14, 15 as shown in FIG. 2F ₁ , and the switching circuit 5 is turned on each time to charge the capacitor 4. , The potential of terminal C is shown in FIG.
As in the case of C, the pitch signal increases stepwise every time one pulse is generated.

Then, the pulse P15 is output from the signal generating circuit 2.
During There occurring, when the pulse P16 shown in FIG. 2F ₃ from the gate circuit 17 is generated, the frequency divider 13 is triggered on the falling edge of the pulse P16, change from "0" to output "1" To do.

Thereafter, every time a pitch signal is generated from the signal generating circuit 2, the same operation as described above is performed to charge and discharge the capacitor 4.

That is, when the output of the frequency divider 13 is "0", the capacitor 4 is in a dischargeable state, and when the output is "1", it is in a chargeable state.

However, since the resistance 8 is set to a resistance value larger than that of the resistance 9, the electric charge charged when the switching circuit 5 is turned on is larger than the electric charge discharged when the switching circuit 6 is turned on. The electric potential of the terminal C is gradually attenuated while repeatedly rising and falling. This becomes an envelope signal containing a beat component.

When the pitch signal F ₁ is generated from the voice generation circuit 2 and the envelope signal is generated from the terminal C as described above, the multiplication circuit 20 generates an acoustic signal which is a combination of the above two signals.

This acoustic signal becomes an attenuating acoustic signal having a beat component, is amplified by the amplifier 21, and is transmitted to the speaker 2
Sounded from 2.

Next, an example in which the pitch signal generated by the signal generating circuit 2 changes by one octave above the pitch will be described with reference to FIG.

By inputting a pulse to the terminals A and B in the same manner as described above, the signal generating circuit 2 and the frequency dividers 12 and 7 are reset, the switching circuit 7 is turned on, the capacitor 4 is charged, and the potential of the terminal C is changed. Becomes as shown in FIG. 3C.

At this time, the signal generation circuit 2 is set by the pitch control signal F to divide the input signal into ⅛, that is, to generate a pitch signal one octave higher than the above pitch signal. It

The signal generating circuit 2 generates a pulse P17 having a cycle of half that in FIG. 2F ₁ as shown in FIG. 3F ₁ .

An output signal as shown in FIG. 3F ₂ is generated from the frequency divider 12, and the flip-flop circuit 4 performs the same operation as described above to generate an output signal as shown in FIG. 3F ₄ .

Since the output of the frequency divider 13 is "0",
The gate circuit 18 is closed, but the gate circuit 19 is open.

[0044] Then, when the pulse P18 as the frequency divider 12 of Figure 3F ₂ is generated from the gate circuit 17, FIG. 3
A pulse P19 is generated like F ₃ , and this pulse P19
Passes through the gate circuit 19, turns on the switching circuit 6 to discharge the electric charge from the capacitor 4, and lowers the potential of the terminal C as shown in FIG. 3C.

The discharge time is the same as above.

The flip-flop circuit 14 is triggered by the trailing edge of the pulse P19 and the output changes to "0", but when the output of the pulse P17 ends, the flip-flop circuit 14 is reset and returns to "1" again.

Thereafter, the same operation as described above is performed every time the pulse P20, P21, P22, which is a pitch signal, is generated from the signal generating circuit 2 as shown in FIG. 3F ₁ , and the capacitor 4 is operated as shown in FIG. 3C. Discharge.

When the pulse P23 is generated from the gate circuit 17 as shown in FIG. 3F ₃ , the frequency divider 1 is operated in the same manner as above.
3 is triggered by the falling edge of this pulse P23, and the output changes from "0" to "1".

While the signal generating circuit 2 is generating the pitch signals P24, P25, P26, P27 as shown in FIG. 3F ₁ , the gate circuit 18 is open (at this time, the gate circuit 19 is closed. Switching circuit 5
Is turned on to charge the capacitor 4, and the potential of the terminal C gradually increases as shown in FIG. 3C.

Thereafter, the capacitor 4 repeats charging and discharging according to the output of the frequency divider 13 to change the potential of the terminal C and generate an envelope signal containing a beat component.

When the pitch signal F ₁ is generated from the voice generation circuit 2 and the envelope signal is generated from the terminal C as described above, the multiplication circuit 20 generates an acoustic signal obtained by combining the two signals in the same manner as described above. The signal is amplified by the amplifier 21 and sounded by the speaker 22.

Since this acoustic signal is synthesized as described above, it becomes an acoustic signal having a beat component corresponding to the pitch of the sound, and an acoustic signal having depth and solidness like natural sound.

That is, as can be seen by comparing FIG. 2C and FIG. 3C, when the period of the pitch signal F ₁ becomes longer (the tone becomes lower), the period of the beat component of the envelope signal also becomes longer accordingly, and the pitch of the tone becomes high. The acoustic signal having a beat component corresponding to the height is generated.

In the above embodiment, the resistance values of the resistors 8, 9 and 10 are set as resistance 8> resistance 9> resistance 10;
By making the resistance value of 2 smaller than that of the resistors 8 and 9, the capacitor 4 can be rapidly charged without increasing the pulse width of the pulse input to the terminal A more than necessary, and the potential of the terminal C can be rapidly increased. You can

By making the resistance value of the resistor 8 larger than the resistance value of the resistor 9, an envelope signal attenuated by the change of the potential of the terminal C is generated without changing the pulse width input to the switching circuits 5 and 6. Can be made.

Further, by appropriately changing the resistance values of the resistors 8 and 9 under the above-mentioned setting conditions, the speed of attenuation can be changed.

[0057]

According to the present invention, a control circuit for adjusting a beat component of an envelope signal including a beat component generated from a charging / discharging circuit according to the frequency of a frequency signal corresponding to the pitch of the tone, and the pitch of the tone. By providing a synthesizing circuit for synthesizing the frequency signal corresponding to the above and the envelope signal to generate an acoustic signal, an acoustic signal having a beat component corresponding to the pitch of the sound can be generated with a simple circuit configuration. , It is possible to obtain a good quality sound that has a depth and solidness close to natural sound at a low cost.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of FIG.

FIG. 3 is a timing chart for explaining the operation of FIG.

[Explanation of symbols]

 2 signal generation circuit 3 charging / discharging circuit 11 control circuit 20 synthesis circuit

Claims (1)

[Claims] 1. A signal generating circuit for generating a frequency signal corresponding to a pitch of a sound, a charging / discharging circuit for generating an envelope signal containing a beat component, and the beat component being adjusted according to the frequency of the frequency signal. An acoustic signal generation circuit comprising: a control circuit; and a synthesis circuit that synthesizes the frequency signal and the envelope signal to generate an acoustic signal.