JP2643717B2 - Music synthesizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tone synthesizer capable of synthesizing a thick tone.

[0002]

2. Description of the Related Art Conventionally, as a method of synthesizing a musical tone waveform,
There is known a technique in which a delay circuit, a filter, and the like are connected in a closed loop to form a loop circuit, an initial tone signal is injected into the loop circuit, the loop circuit is circulated, and an output tone signal is extracted from an appropriate position. .

For example, Japanese Patent Publication No. 58-58679 discloses a technique of forming a harmonic separated from an integer harmonic series by inserting a filter having a non-linear phase characteristic in a loop circuit. As a filter, for example, an all-pass filter (hereinafter, referred to as an all-pass filter) having a gain of “1” at all frequencies and having a predetermined non-linear phase characteristic
Etc.). According to this technique, a relatively complicated musical sound can be synthesized by outputting high-frequency harmonics using an APF or the like.

[0004] Japanese Patent Application Laid-Open No. 2-300795 also discloses a tone synthesizer including a delay circuit and an APF in a similar loop circuit.

[0005]

Incidentally, the above-mentioned Japanese Patent Publication No. 58-58679 and Japanese Patent Application Laid-Open No. 2-300795.
Each of the tone synthesizers disclosed in the above publications is basically an attenuated tone synthesis system in which a drive waveform is injected into a loop circuit and filtered while looping the drive waveform. Therefore, it is difficult to generate a tone having a frequency component not included in the drive waveform, and there is a problem that it is difficult to generate a thicker tone.

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the prior art, the present invention provides a tone synthesizer having a loop circuit for circulating a tone signal in a tone synthesizer having a frequency component not included in a drive waveform injected into the loop circuit. It is an object of the present invention to be able to generate a thicker musical sound.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, a musical sound synthesizer according to the present invention circulates a musical sound signal.
And a loop circuit provided in the loop circuit.
Dividing a musical tone signal into a positive component and a negative component
Stage and phase characteristic control means provided in the loop circuit
The positive tone signal obtained by the dividing means
Differentiate the phase characteristics from those of the negative tone signal
And output from the phase characteristic control means.
And adding means for adding the obtained two signals.
Features. A loop circuit for circulating a tone signal; a dividing unit provided in the loop circuit for dividing the tone signal into a positive component and a negative component; and a dividing unit provided in the loop circuit. First phase characteristic imparting means for imparting a phase characteristic to the obtained positive tone signal;
A second phase characteristic applying means for applying a phase characteristic to the negative tone signal obtained by the dividing means provided in parallel with the first phase characteristic applying means in the loop circuit; Mixing means for mixing output signals from the first and second phase characteristic imparting means provided.

The loop circuit may include a conventionally known delay circuit and filter means. However,
As the first phase characteristic applying means and the second phase characteristic applying means provided in parallel in a loop circuit, those having both functions of a delay circuit and a filter means may be used. As these phase characteristic imparting means, for example, APF
Is used. A general filter other than the APF can be applied as long as it has a non-linear phase characteristic. However, if the APF is used, the present invention can be realized without requiring complicated control.

[0009]

Since the tone signal circulating in the loop circuit is divided into a positive component and a negative component, and each of them is given a phase characteristic and mixed again, frequency components not included in the drive waveform Can be synthesized.

[0010] By appropriately selecting the phase characteristics of the first phase characteristic applying means and the second phase characteristic applying means, a thick musical tone can be synthesized. For example, simply inserting an APF into a loop circuit as in the past,
(Although it is effective from the viewpoint of changing the tone,)
The phase relationship between the basic waveform and the harmonic wave goes out of order. That is, even when it is desired to change only the timbre without changing the phase relationship (harmonic relationship) between the fundamental wave and the harmonic, the pitch is shifted. According to the present invention, if the harmonic components are shifted in the opposite directions between the first phase characteristic applying unit and the second phase characteristic applying unit, the width of each harmonic component is widened, but the width at the center is increased. The pitch can be at the position of the basic waveform. Therefore, a musical sound as if performing an ensemble can be synthesized, and the sound becomes thicker.

[0011]

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

FIG. 1 shows a block diagram of an electronic musical instrument using a tone synthesizer according to one embodiment of the present invention. The electronic musical instrument of this embodiment includes a keyboard 1 having a plurality of keyboard keys, a keyboard interface 2 for passing outputs (key-on signals, key-off signals, key codes, etc.) from the keyboard 1 to a bus line 11. The electronic musical instrument includes a central processing unit (CPU) 3, a read only memory (ROM) 4, and a random access memory (RAM) 5 for controlling the overall operation of the electronic musical instrument. The ROM 4 stores programs executed by the CPU 3, various tables, constants, and the like. Various work registers and flags are assigned to the RAM 5.

The electronic musical instrument also includes an operation panel 6 including a plurality of switches to which various functions are assigned, a panel interface 7 for passing an output from the operation panel 6 to a bus line 11, a CPU 3 A tone synthesis circuit 8 for synthesizing a desired tone signal based on the instruction of
And a sound system 9 for generating a musical tone from a speaker 10 based on a musical tone signal from a musical tone synthesizing circuit 8.

FIG. 2 shows a detailed block configuration of the tone synthesis circuit 8. The tone synthesis circuit 8 includes the drive waveform generation circuit 2
1, adder 22, delay circuit 23, half-wave rectifier circuit 24,2
5, APFs 26 and 27, adder 28, low-pass filter (hereinafter referred to as "LPF") 29, conversion table 30,
An APF coefficient generation circuit 31 and a filter coefficient generation circuit 32 are provided. A loop circuit is configured by the adder 22, the delay circuit 23, the half-wave rectifier circuits 24 and 25, the APFs 26 and 27, the adder 28, and the LPF 29. These components are all composed of digital circuits.

The instruction for synthesizing a tone signal from the CPU 3 is made by outputting a key code KC, a key-on pulse KONP, a tone color control signal TC, and an initial touch IT. The key code KC specifies the pitch (pitch) of a musical tone to be synthesized. Key-on pulse KONP
Is a pulse signal generated when a key on the keyboard is turned on. The tone color control signal TC is a signal for designating the tone color of a musical tone to be synthesized. Initial touch IT
Represents touch information when a key on the keyboard is turned on. The CPU 3 sends these signals to the tone synthesis circuit 8.

In the tone synthesizing circuit shown in FIG. 2, a drive waveform generating circuit 21 receives a tone color control signal TC, a key code KC and a key-on pulse KONP,
A tone signal (drive waveform) having a designated timbre and pitch is generated sequentially from the time when the ONP is generated and output to the adder 22. This drive waveform is a sequence of digital signals representing the amplitude value at each sample point of the predetermined clock, and is a waveform for one cycle.

The driving waveform input to the adder 22 is an LPF
The result of the addition is input to the first stage of the delay circuit 23. The delay circuit 23 is configured by a shift register, and each stage of the shift register is configured by a number of flip-flops corresponding to the number of bits of the digital signal of the driving waveform input from the adder 22. The data of each stage is shifted to the next stage according to a predetermined clock signal. The data of the last stage is output to the half-wave rectifier circuits 24 and 25. The number d of stages of the shift register of the delay circuit 23 is determined according to the pitch of a musical tone to be synthesized. Specifically, the conversion table 30 determines the number d of stages according to the key code KC. The stage number d is a number for storing one cycle of the musical tone signal of the pitch.

The data of the last stage of the delay circuit 23 is input to half-wave rectifier circuits 24 and 25. Half-wave rectifier circuits 24, 25
Divides the tone signal circulating in the loop circuit into positive and negative. That is, the half-wave rectifier circuit 24 outputs only the positive signal of the input tone signal to the APF 26, and when the input is negative or "0", the output is "0". Conversely, the half-wave rectifier circuit 25 converts only the negative
Output to F27. When the input is positive or “0”, the output is set to “0”.

APFs 26 and 27 are primary APFs, respectively.
The specific configuration will be described later with reference to FIG.
The APFs 26 and 27 have a gain of “1” in all frequency ranges.
And a phase characteristic such that the phase delay with respect to the frequency changes nonlinearly. The amount of phase delay in the APFs 26 and 27 is determined according to the coefficients k1 and k2 input to them. The coefficients k1 and k2 are calculated by the APF coefficient generation circuit 3
1 is output according to the tone color control signal TC and the initial touch IT. For example, after the key-on pulse KONP is input, the APF coefficient generation circuit 31 outputs the coefficients k1 and k2 so that the larger the initial touch IT, the larger the phase delay amount, or the phase delay amount changes according to the tone. Output the coefficients k1 and k2.

The positive tone signal input to the APF 26 is phase-delayed according to the coefficient k1 and input to the adder 28. The negative tone signal input to the APF 27 is phase-delayed according to the coefficient k2 and input to the adder. An adder 28 adds these input signals and outputs the addition result as LP
Output to F29.

The LPF 29 is a filter having a low-pass characteristic that cuts frequency components higher than a predetermined cutoff frequency and passes components below the cutoff frequency. The cutoff frequency is determined according to the coefficient fc output from the filter coefficient generation circuit 32. The filter coefficient generation circuit 32 starts the timbre control signal TC and the initial touch I
The coefficient fc is output according to T. LPF in loop circuit
With the provision of 29, after a sufficient time has elapsed, higher-order harmonic components are attenuated, and an output waveform having only lower-order harmonic components is obtained. LPF29
Is input to the adder 22 and is added to the drive waveform. The output of the adder 22 is output to the sound system 9 as a synthesized tone signal.

As described above, the drive waveform circulates through the loop circuit, and the tone signal is synthesized. In particular, in this embodiment, the tone signal is divided into a positive component and a negative component in the loop circuit, and each of the divided signals is independently APF
26 and 27, and then added again. Therefore, each time the circuit circulates through the loop circuit, the phases of the positive signal and the negative signal can be shifted independently, and new harmonics (harmonics whose frequency is shifted from an integral multiple of the fundamental frequency) are added. Signal of the higher harmonic component generated by the above method.
This makes it possible to impart a chattering effect to the synthesized musical sound.

FIG. 3 shows a circuit example of the APFs 26 and 27. The APFs 26 and 27 include adders 41 and 42 and a multiplier 4
3 and 44 and a delay circuit 45. Delay circuit 4
Reference numeral 5 denotes one clock of the circulating tone signal (the same clock signal as the clock input to the delay circuit 23 is input).
This is a delay circuit that delays the output by an amount.

The adder 41 adds the output signal from the multiplier 44 to the input signal from the half-wave rectifier circuits 24 and 25.
The output signal of the adder 41 is input to the adder 42 after being delayed via the delay circuit 45 and also to the multiplier 43. The multiplier 43 multiplies the signal from the adder 41 by a coefficient k, and outputs the multiplication result to the adder 42. The output signal from the delay circuit 45 is input to the multiplier 44. Multiplier 4
4 multiplies the signal from the delay circuit 45 by a coefficient −k and outputs the multiplication result to the adder 41. The adder 42 includes the multiplier 4
3 and the output signal from the delay circuit 45, and outputs the addition result to the adder 28 at the subsequent stage. The coefficients k and -k are values between -1 and 1, and the APF26
In this case, k = k1, and in the APF 27, k = k2.

FIG. 4 shows waveforms at various parts when the tone synthesis is performed by the tone synthesis apparatus of FIG. FIG. 4A shows a sine wave input waveform generated by the drive waveform generation circuit 21. When such a sine wave is input to the loop circuit, the output waveform of the half-wave rectifier circuit 24 that cuts out the positive component is as shown in FIG. Further, the waveform of FIG.
, It is distorted as shown in FIG. FIG. 4D shows a waveform obtained by performing the same processing on the negative side and adding the output of the positive APF 26 and the output of the negative APF 27 by the adder 28.

FIG. 5 shows the first several tens of waveforms output as a synthesized tone signal when the processing as shown in FIG. 4 is continuously performed. It can be seen that the first simple sine wave produces various harmonics over time, and gradually attenuates due to the action of the LPF 29. Due to such a waveform change, the synthesized sound has a sound like a sitar, for example.

According to the above embodiment, the average delay time of the synthesized musical tone waveform can be kept constant. In other words, the phase delay amount of each frequency component in the vicinity of the fundamental wave is controlled by controlling the amount of phase delay of each of the positive and negative divided waveforms to be positive and negative around a predetermined constant reference value and to have the same absolute value. Can be kept constant. Therefore, it is possible to increase the sound thickness without changing the basic pitch. To do so, for example, the coefficients k1 and k2 of the APFs 26 and 27 have different signs but the same absolute value.

According to the above embodiment, since the positive and negative signals are added, the signal of the DC component is not increased. Therefore, it is possible to suppress the occurrence of an attack and a click noise at the time of release which are often generated in the conventional method.

Furthermore, if the APF is used as in the above embodiment, the amplitude frequency characteristic of the APF is flat over the entire band, so that even if the coefficient of the APF is changed variously, a stable circuit can be formed without causing overflow. can do.

In the above embodiment, the tone color control signal TC and the initial touch I
Although the coefficients k1 and k2 are determined according to T, a predetermined envelope may be further added to these coefficients k1 and k2.

[0031]

As described above, according to the present invention, the tone signal circulating in the loop circuit is divided into positive and negative components, and each component is independently given a phase characteristic and mixed. Therefore, it is possible to generate a musical tone having a frequency component not included in the drive waveform injected into the loop circuit, and to generate a musical tone having a greater thickness.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electronic musical instrument using a musical sound synthesizer according to an embodiment of the present invention.

FIG. 2 is a detailed block diagram of a tone synthesis circuit.

FIG. 3 APF circuit example

FIG. 4 is a waveform diagram of each part when a tone synthesis is performed by the tone synthesis apparatus of the embodiment.

FIG. 5 is a waveform diagram output as a synthesized tone signal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... keyboard, 2 ... keyboard interface, 3 ... central processing unit (CPU), 4 ... read-only memory, 5 ... random access memory, 6 ... operation panel, 7 ... panel interface, 8 ... tone synthesis circuit, 9 ... sound system ,
DESCRIPTION OF SYMBOLS 10 ... Speaker, 11 ... Bus line, 21 ... Drive waveform generation circuit, 22 ... Adder, 23 ... Delay circuit, 24, 25 ...
Half-wave rectifier circuit, 26, 27 ... APF, 28 ... Adder, 2
9 low-pass filter, 30 conversion table, 31 A
PF coefficient generation circuit, 32 ... Filter coefficient generation circuit 32.

Claims (2)

(57) [Claims] A loop circuit for circulating a tone signal; a dividing unit provided in the loop circuit for dividing the tone signal into a positive component and a negative component; and a loop circuit provided in the loop circuit. Phase characteristic control means.
The phase characteristic of the positive tone signal obtained by the dividing means
And the phase characteristics of the negative tone signal
And the two signals output from the phase characteristic control means are added.
A tone synthesis device comprising: (2) A loop circuit for circulating the tone signal, The tone signal provided in the loop circuit has a positive
Dividing means for dividing into minutes and negative components; Obtained by the dividing means provided in the loop circuit.
A first phase for imparting phase characteristics to the received positive tone signal
Characteristic imparting means; Parallel to the first phase characteristic applying means in the loop circuit
, The negative tone signal obtained by the dividing means.
Second phase characteristic imparting means for imparting a phase characteristic to the signal, The first and the second provided in the loop circuit
Mixing means for mixing the output signals from the phase characteristic imparting means
When A tone synthesizer comprising: