JPS6132896A - Frequency control system for electronic musical instrument - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a frequency control method for an electronic musical instrument that modulates and controls the frequency of musical tones using noise.

[Prior art]

Conventionally, the method of modulating the frequency of generated musical tones with noise uses a pseudo-random pulse generation circuit, and by passing the white noise output from this pseudo-random pulse generation circuit through a filter, it is possible to adjust the key press position or after the key press. There is a method in which the frequency of musical tones is modulated by noise whose pitch window changes with time. In addition, by using the FM modulation method and modulating the frequency of the musical sound waveform with the modulation waveform applied with feedback, the frequency of the musical sound is modulated by noise whose pitch window changes as the modulation waveform and the temporal volume of the musical sound waveform change. There is a way.

[Problems with conventional technology]

In the former method, VCO (voltage controlled oscillator), VCF
(voltage controlled filter), DCF (digital controlled filter), etc. are required, so analog synths and DC
It cannot be used with anything other than digital synthesizers equipped with F. Furthermore, the latter method has a problem in that the configuration is complicated.

By adding and subtracting random signals and using the frequency information generated based on the added and subtracted values, you can use a simple configuration to generate noise that changes the pitch feeling due to the key press position or the time change after the key press. The present invention aims to provide a frequency control method for an electronic musical instrument that modulates the frequency of musical tones.

[Key points of the invention]

The gist of the present invention is that the key code generating means generates a key code according to the pitch, the random signal generating means generates a random signal, and the Addition and subtraction means for adding and subtracting the random signals generated by the random signal generation means;
An electronic musical instrument comprising a frequency information generating means that generates frequency information based on the output of the addition/subtraction means, and a musical tone signal generating means that generates a musical tone signal of a corresponding pitch based on the frequency information generated by the frequency information generating means. This is based on the frequency control method.

〔Example〕

Hereinafter, the present invention will be explained according to embodiments shown in the drawings. FIG. 1 is a block circuit diagram thereof, and numeral 1 in the figure is a keyboard, on which white keys and black keys are arranged in a predetermined arrangement. A binary pitch code (hereinafter referred to as a key code) is assigned to each key, and the key code is given to the frequency data generator 4. Note that the key code in this example is the first semitone unit representing the white key and black key.
The keyboard 1 generates a key code consisting of the first binary code and the second binary code. Note that the keyboard 1 may generate a key code of only the first binary code, with the second binary code being all zeros.

That is, FIG. 2 shows such a key code, and A
Each bit from 6 to AI is an upper key code and represents the first binary code. Each bit of Ao-A is a lower key code and represents the second binary code. For example, if the key code for A4 (440 Hz) is 1000000000000, a group of key codes as shown in FIG. 3 will be obtained corresponding to each scale. Of course, the relationship between the scale and the key code can be changed in any way as long as it satisfies the cent proportional relationship shown in FIG. Note that the binary actual data in FIG. 2 will be described later.

In addition to these key codes, the keyboard 1 provides a trigger signal to the frequency envelope key code generator 2, which causes the frequency of the generated musical tone to fluctuate, for example, at the start of sound generation, or, for example, to generate attack, decay, etc.
Envelope signals having different phases such as sustain and release may be generated to bring about temporal changes in the musical tone frequency. The frequency envelope key code generator 2 also generates cent proportionality as shown in FIG. In other words, a pitch code (hereinafter also referred to as a key code) in units of 1.5625 cents is generated. Of course, the binary code on the upper bit side A, ~A12 may be all 0, and a key code composed only of the binary code on the lower bit side A, -A, may be generated.

Reference numeral 3 in FIG. 1 is a vibrato key code generator 3, which generates a vibrato pitch code (hereinafter referred to as a key code) that changes in a sine wave or triangular wave. Also, the third semitone unit is
, and below it a fourth binary code in the same format as the second binary code, in units of a predetermined cent.

In this embodiment, only a key code for vibrato is generated, but a key code for frequency modulation by portamento, glissando, tuning, etc. may be generated, and this is provided to the frequency data generating section 4. You can do it like this.

Reference numeral 5 in FIG. 1 is a random pulse generator 5, which generates a 1-bit random pulse. As shown in FIG. 4, in this random pulse generating section 5, an output signal from an output terminal Qt< of a 25-bit shift register 6 is inputted to one end of an exclusive OR gate 7-. Further, the output signal from the output terminal Q2 is input to the other end of the exclusive OR gate 7, and becomes the output signal of the random pulse generator 5. Further, the output of the exclusive OR gate 7 is input to the input terminal IN of the shift register 60.

Then, the random signal generated from the keyboard 1 and the frequency engineering μm key generation section 5 is transmitted to the A of the frequency data generation section 4.
-D is applied to the input terminal and generates frequency data proportional to the frequency.

FIG. 5 shows details of the frequency data generator 4.
Reference numeral 41 in FIG. 5 is a binary adder/subtractor, which receives the key code given from the A input terminal, the frequency envelope key code given from the B input terminal, the vibrato key code given from the C input terminal, and the D input terminal. Add the random pulse given from the end (or subtract the frequency envelope key code, vibrato key code, and random pulse from the key code as necessary), and add the fifth one in semitone units from the key code output. Binary code (
As-A1. ) is applied to the frequency information ROM 42 for each semitone to output frequency information.

This frequency information is proportional to frequency, and has a ratio of 2+2 (= 2 mounds = 1.059463094) between medium tones. In addition, this frequency information ROM for each semitone
52 may store frequency information for the entire range, but it is also possible to store frequency information corresponding to a 12-tone scale in a specific octave in ROM and shift it according to the octave in which it is generated. Frequency information for each scale in the entire range may be obtained. In that case, a code corresponding to the scale and octave is obtained from the fifth binary code of the key code, and the frequency information read out according to the scale code is shifted by the number of bits according to this octave code. In other words, the frequency ratio between one octave and one octave is 2
(=21200'), it is sufficient to perform such processing.

Further, among the above key code outputs, the sixth binary code (Ao = As) proportional to cents below the semitone is output by the converter 4.
3. This conversion unit 43 converts the cent data expressed in the sixth binary code into binary real data, and specifically, as shown in the rightmost column of FIG. 2. That is, the sixth binary code (Ao to A4) is ooo
ooo to 111111, i.e. 0 cents to 98
．． 4375 (=50+25+12.5+6.25+3.
125+1.5625) cents, and the function of this converter 43 is to convert it into binary actual data as shown in Table 2 accordingly.

Table 2 As such a converter 43, as shown in FIG.
It can be configured with OM. In FIG. 6, the sixth binary code (AO to A11) serves as an address signal, and the ROM 43 outputs the corresponding binary actual data.

That is, in this example, compared to the binary actual data shown in Table 2, for example, when the 6th binary code 80~person is all "1", the lower 6 bits of the binary actual data are There is a slight error of 111100. but,
Such a slight error poses no practical problem. With this configuration, the circuit scale can be further reduced.

The output of the converter 43 is given to the interpolator 44 together with the output of the frequency information ROM 42 for each semitone.

This interpolation section 44 obtains frequency information of a semitone or less, and is generally configured with a multiplier, and converts the frequency information for each semitone into the frequency information sent from the ROM 42 and the binary output sent from the conversion section 43. By multiplying the data, frequency data of the musical tone to be generated is obtained.

This frequency data is sent to the phase angle calculation circuit 8 shown in FIG. The output of this -phase angle calculating circuit 8 is not only given to the N input terminal of the waveform generating section 9 but also fed back to its own input terminal. That is, this phase angle calculation circuit 8 accumulates the frequency data output from the frequency data generator 4 each time a fixed clock signal is generated, and the accumulated output is
You can now specify the phase of the waveform.

This waveform generator 9 has a circuit configuration as disclosed in Japanese Patent Application No. 57-221266, and changes the step speed of the waveform address before and after the phase specified by the modulation signal.
It outputs a waveform signal containing harmonic components by intentionally distorting a waveform such as a sine wave, and internally contains an arithmetic circuit to obtain such an address signal, a waveform ROM for sine waves, etc. The output is sent to the envelope multiplier 10 from the O output terminal.

The envelope multiplier 10 is further supplied with a signal specifying a volume envelope to be output from an envelope control signal generator 11. Note that a trigger signal is output from the keyboard 1 and supplied to the envelope control signal generating section 11, and outputs the above-mentioned signal.

The envelope multiplier 10 then combines the waveform signal output from the waveform generator 9 with the envelope control signal generator 1.
The signal is multiplied by the volume envelope control signal output from 1, and then converted into an analog signal by a D/A converter, and appropriately amplified to produce an audio signal.

Next, the operation of this embodiment will be explained.

For example, when the key of the scale A4 is operated on the keyboard l, the key code rloo0000000000J is outputted and applied to the A input terminal of the frequency data generating section 4.

Furthermore, random pulses are generated from the random pulse generator 5. This random pulse is added to bits A, , and A of the bits A0 to AH indicating the key code.

As a result, the binary adder/subtracter 41 in the frequency data generating section 4 obtains a key code in which the key code of 4. and a random pulse are added to the above-mentioned scale.

In other words, a key code specifying the pitch of A, +250 cents, that is, an upper binary code corresponding to scale B4,
A key code that changes to a lower binary code of 50 cents is randomly obtained from the binary adder/subtractor 4, and as a result, the frequency information output from the frequency information ROM 42 for each semitone is converted into a binary code output from the converter 43. The data is interpolated (corrected) to obtain frequency data of the pitch.

As a result, the frequency data output from the frequency data generator 4 changes randomly, and as a result, the waveform signal output from the waveform generator 9 has noise added to it. Here, when another key is pressed, the degree of modulation of the key code by random pulses changes depending on the pitch. The higher a key is played, or the higher a key is played in a single note window, the more it becomes possible to obtain a musical tone whose musical frequency is modulated by noise with a low pitch. Therefore, a musical tone whose musical tone frequency is modulated by noise whose pitch feeling changes depending on the pressed key position is obtained.

Furthermore, by adding the frequency envelope key code outputted from the frequency envelope key code generating section 2 to the binary adder/subtractor 41, it is possible to add the frequency envelope key code outputted from the frequency envelope key code generator 2 to the binary adder/subtractor 41. It becomes possible to obtain a musical tone whose musical tone frequency is modulated.

In the above embodiment, the waveform address signal is obtained by accumulating the frequency data output from the frequency data generator 4, but in addition, this frequency data may be preset and a predetermined value may be subtracted from this frequency data. By doing so, an address signal may be obtained in which the address of the waveform is incremented each time a predetermined condition is reached.

Further, in the above embodiment, the key code has a 13-bit structure, but the number of bits can be changed depending on the frequency accuracy.

Furthermore, in the above embodiment, the random pulse from the random pulse generator 5 is added to the bits A, , A, , of the bits of ~A,2 indicating the key code, but the invention is not limited to this, for example. It may be added to only one bit like the AIH bit. Here, the greater the weighting of the random pulse with respect to the key code, the deeper the degree of modulation, and conversely, the smaller the weighting, the shallower the degree of modulation.

〔Effect of the invention〕

As explained above, the present invention provides a frequency control method for electronic musical instruments that adds and subtracts random signals to predetermined bits of a key code and generates musical tones by using frequency information generated based on the added and subtracted values. With this, it is possible to obtain, with a simple configuration, a musical tone to which noise is added, the pitch of which changes depending on the position of the key pressed or the change in time after the key is pressed.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, and FIG. 2 is a block circuit diagram of an embodiment of the present invention.
3 is a diagram for explaining the relationship between each scale and the key code, and FIG. 4 is a diagram for explaining the random pulse generator 5 of FIG. 1. FIG. 5 is a detailed circuit diagram of the frequency data generating section 4 of FIG. 1, and FIG. 6 is a diagram showing an example of the circuit of the converting section 530 of FIG. 1...Keyboard, 4...Frequency data generation section, 5...
Random pulse generator, 6...shift register, 41
...Binary adder/subtractor. 3 eyes of potato, 4 pieces of grass, 6 pieces of grass

Claims (1)

[Claims] a key code generating means for generating a key code according to the pitch; a random signal generating means for generating a random signal;
Addition and subtraction means for adding and subtracting a random signal generated by the random signal generation means to predetermined bits of the key code generated by the key code generation means; and a frequency information generation means for generating frequency information based on the output of the addition and subtraction means. and musical tone signal generating means for generating musical tone signals of corresponding pitches based on the frequency information generated by the frequency information generating means.