JPS599072B2 - Non-integer harmonic effect device for electronic musical instruments - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-integer harmonic effect device for an electronic musical instrument that generates a sound closer to that of a natural musical instrument.

Generally, a musical tone signal generated by an electronic musical instrument is composed of a fundamental frequency and integer overtones having a specific spectral amount relative to the fundamental frequency.

On the other hand, recent research has revealed that the harmonic components of natural musical instruments such as the piano are not exactly integral multiples of the fundamental frequency, but are often slightly deviated from integral multiples.

The deviation is from several cents to several tens of cents based on the integral multiple value. In this way, musical tones are formed by having multiple components with frequencies slightly different from integer overtones, such as second overtones, triple overtones, etc., so compared to the musical tones of electronic musical instruments, It can be said that it has a rich resonance and a glossy tone. An object of the present invention is to provide an electronic musical instrument that can produce musical tones closer to natural instruments by electronically generating musical tones that include non-integer harmonics, in contrast to conventional electronic musical instruments that produce simple musical tones formed by integer harmonics. It's about doing.

Embodiments of the present invention shown in the drawings will be described below.

FIG. 1 is a block diagram showing an embodiment of the present invention.
2 is an electronic musical instrument having a keyboard such as an electronic organ or a synthesizer, and 2 is a door wave device in which 21 low-pass type and 22 high-pass type are connected in parallel. As shown in FIG. 2, the frequency relationship of each wave wave device is such that the cutoff frequency of the low-pass P wave device 21 is the fundamental frequency f. The cutoff frequency of the high-pass door wave device 22 is the second harmonic frequency 2 of the fundamental wave.
Select fo. Furthermore, since the output frequency of the musical instrument varies in high and low, each of the P-wave devices uses a voltage-controlled door filter (VCF) whose cut-off frequency can be changed, and the terminal of the pitch signal TH of the electronic musical instrument 1 is connected to the pitch signal TH. Preferably, it is connected to the control terminal of the VCF. 3 is a signal variable delay element BB
D (bucket brigade type transfer device) CCD (charge coupled device)
etc., and only the output of the high-pass P-wave device 22 is applied to this element.

Reference numeral 4 denotes a voltage-controlled clock pulse generation circuit (VCO) that generates pulses for signal transfer of the BBD element 3, and by making the period variable, harmonic signals of musical tones applied to the BBD element 3 are generated. Modulate the frequency.

Reference numeral 5 denotes a clock frequency modulation signal generation circuit, which is activated by a key press signal and controls VC04 as described above.

Reference numeral 6 indicates a signal synthesis amplifier, 7 a speaker, and 8 a low-pass f-wave device.

The fundamental wave component of the musical tone signal obtained from the electronic musical instrument 1 by the key press operation is selected by the low-pass f-wave generator 21 and reaches the signal synthesis amplifier 6 as it is, where it is converted into harmonics of the second harmonic and above. The component (having a frequency that is an integer multiple of the fundamental wave) undergoes frequency modulation by the BBD element 3 to become a frequency that deviates from the integer harmonic, and the signal is smoothed by the f-wave generator 8 and reaches the synthesis amplifier 6.

The non-integer overtone components are delayed by the BBD element transfer time compared to the fundamental wave component, but this value is within a few milliseconds, so it is usually not perceptible to the human ear.

The output of the signal synthesis amplifier 6 is a combination of both components and contains non-integer overtones closer to those of natural musical instruments, so that a glossy tone can be obtained from the speaker 7. Next, the generation of non-integer overtones will be explained in detail.

First, a specific circuit diagram of the clock frequency modulation signal generation circuit 5 is shown in FIG. C represents a capacitor, R represents a resistor, and FET represents a field effect transistor. When a key press signal is obtained in the electronic musical instrument 1 and the capacitor C is charged using the key press signal, the charging characteristic is given by the following equation (:r)<1).
Generally, K is shifted from the nth stage to the (n+1)th stage.
L. Em is the maximum value of the key press signal, and this characteristic is shown in FIG. 4A for explaining the operation.

In the figure, t-TO is the key press time. The capacitor charging potential given by equation (1) is applied as a control voltage to the VCO 4 via a voltage follower circuit (not shown). Therefore, the clock pulse frequency changes as shown in FIG. 4B. The oscillation frequency of CO4 is given by the instantaneous phase angle of the following equation (2). Here, ωc is the angular frequency of the clock pulse during steady state, and ωd is the value that determines the deviation rate of the clock pulse. Next, the period T1 of the clock pulse at the time when the musical tone signal is input to the BBD element 3 and sampled is here, where t indicates the elapsed time from the time of key depression.

Therefore, after T1 has elapsed, the signal sampling point is shifted from the first stage of the BBD element 3 to the second stage.

Next, the time interval T2 shifted from the second stage to the third stage is as follows.
As shown in FIG. 5, the delay time Td from the input of the musical tone signal to the output of the musical tone signal by the element 3 is calculated by the above-mentioned equation (6). Appears on the output terminal after the indicated time has elapsed.

At this time, the sampling period TOut has a value different from Tin, and the signal is subjected to frequency modulation due to expansion or contraction of this period.

Since Tin is given by the above equation (3) and TOut is given by the equation (5), the input signal frequency Fsi and the output signal frequency Fs
Taking the ratio with O, it becomes. When the rate of change in the output frequency is determined using t as a variable in equation (7), the curve shown in FIG. 4C is obtained. In the figure, a frequency modulation rate of 1.03 when a key is pressed corresponds to a frequency deviation of approximately 50 cents.

The deviation of 50 cents is a value determined by ωC)ωD and the number of BBD stages N, and can be obtained experimentally or by simulating with a calculator. Note that in this example, when a key is pressed, the sound has a frequency that deviates from an integer harmonic, and as time passes after the key is pressed, the sound gradually approaches the sound of an integer harmonic. The degree of asymptosis is determined by the frequency modulation signal generation circuit 5
Determined by the CR time constant of Next time the key is released, the key release signal is applied to the FET which was non-conducting until then in FIG. 3 and it becomes conductive, so the capacitor C
The remaining charge is instantly discharged via the FET.

Therefore, the key release signal is preferably formed as a single pulse. Although the frequency modulation signal generation circuit 5 has been described as a CR circuit, it can be configured using a Miller integrator or the like.

By using a Miller integrator, it is possible to lengthen the time it takes to asymptote to integer overtones. In this way, according to the present invention, integer harmonics are extracted from the fundamental wave and frequency modulation is applied using a variable delay element, so that when a key is pressed, the sound deviates most from an integer multiple frequency, and as time passes, it approaches an integer harmonic. Since the synthesized sound is obtained and synthesized with the fundamental wave again, the synthesized sound is closer to that of a natural instrument.

Therefore, even if it is an electronic musical instrument, it is possible to fully demonstrate the performance effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the characteristics of the wave generator 2 in FIG. 1, and FIG. 3 is a specific circuit diagram of the frequency modulation signal generator in FIG. 1. , FIG. 4 is an explanatory diagram of the operation of FIG. 1, and FIG. 5 is a diagram showing signals at the input/output terminals of the BBD element of FIG. 1. 1...Electronic musical instrument, 2...Sawanami instrument,
21...Low pass type P wave device, 22...
High-pass wave wave device, 3... BBD element, 4 ・
・・・・・・Voltage controlled clock pulse generation circuit, 5 ・
・・・・・・Frequency modulation signal generation circuit, 6 ・・・・・・
Signal synthesis amplifier, T...Speaker, 8...
...Low-pass type P-wave device.

Claims (1)

[Claims] 1. An electronic musical instrument that generates a musical tone signal containing a fundamental wave component and its integral harmonics by pressing a key, which includes a filter circuit that divides the musical tone signal into a fundamental wave component and its integral harmonic components, and a filter circuit to which the integral harmonic component signal is applied. A variable delay element, a voltage-controlled oscillator that generates a clock pulse to drive the variable delay element, and a voltage modulation that is controlled by a key press signal so that the voltage changes smoothly from the time the key is pressed and becomes constant after the required time. Clock frequency modulation signal generation for supplying a control signal to the voltage controlled oscillator so that the voltage controlled oscillator generates a clock pulse whose frequency increases smoothly from the time of key depression and becomes constant after a required time. 1. A non-integer overtone effect device for an electronic musical instrument, comprising a circuit for synthesizing the output of the variable delay element and the fundamental wave component.