JPS5842475B2 - Denshigatsukiniokerugakuonhakeihatseisouchi - Google Patents

Description

[Detailed description of the invention] The present invention relates to a musical sound waveform generator.

Conventionally, as a device for generating musical tone waveforms, (1) a device is provided with a storage device for storing a certain musical tone waveform itself, and generates musical tone waveforms by reading out the memory device as appropriate.

(2) Instead of storing a specific musical sound waveform itself, a storage device is provided that samples the fundamental wave and multiple high-frequency sine waves relative to the fundamental wave, and stores the amplitudes as digital information, and this storage device is read out. ,
A device that appropriately multiplies the relative level of each read waveform output according to the tone to be obtained, and then adds and synthesizes each waveform output to generate a musical sound waveform.

There is.

However, in method 1), it is not easy to change the memory contents, so in order to obtain a plurality of various tone waveforms,
The device (2) requires a large number of unique storage devices each corresponding to a desired tone waveform, and has the disadvantage that it is not possible to obtain an arbitrary tone waveform. Although it has excellent features such as being able to synthesize musical sound waveforms, the circuit configuration, especially the multiplier, is complicated.
Furthermore, since the calculation is performed in real time, the clock frequency becomes high, and the system has the disadvantage that the entire system must operate at a high frequency.

The present invention eliminates the above-mentioned drawbacks, and its main purpose is to provide a musical tone generator that can easily digitally synthesize musical sound waveforms.Another purpose of the present invention is to provide an arbitrary waveform f ( An object of the present invention is to provide a musical tone generator capable of easily synthesizing x) in the form f(x) = ΣCn - F(X), which is the product of the coefficient Cn and the orthogonal function F (x) that can be expressed as 1.0. .

A feature of the present invention is that the orthogonal function is J.

It has been found that the use of the Walsh function proposed by Paul Walsh is convenient for digitizing musical tones, and it has become possible to create a musical tone generator that can generate arbitrary musical sound waveforms using simpler electronic circuits.

The said Wal presented by Mr. Walsh, J.
Mathematically, the sh function is a complete orthonormal system, and it is composed only of binary values of +1 and -1.

As an example, if we show the Walsh functions up to the 7th order, then the 1st
It will look like the figure.

Proof that the function f (t) can be expressed by giving appropriate weights to this Wa 1 sh function is given by J , W
Mr. al sh conducted this research and derived the relational expressions shown in equations 1) and (2).

If we convert the binary values of +1 and -1 of the Walsh function presented by Mr. J. Walsh into binary values of 1 and O in order to make it easier to use as a digital circuit, and take the musical sound waveform f(t), the Walsh-Fourier It can be expanded into a series and can be expressed by the following equations (3) and (4).

Here, ai is a Walsh coefficient (5equency spectrum) corresponding to the frequency spectrum of the trigonometric function system.

As mentioned above, the Walsh function is a complete orthonormal system having a value of 1.0, and has properties very similar to the Fourier series of the trigonometric function system.

However, when comparing the Walsh function and trigonometric functions, the Walsh function has the following characteristics.

(1) By using the Walsh function, any musical sound waveform can be synthesized, similar to the Fourier series of trigonometric functions.

(2) Since the Walsh function is composed of binary values of 1.0, it is an optimal function for digital circuits.

(3) The Walsh function generation circuit can be constructed from a simple digital circuit.

In addition to this Walsh function, there are orthogonal functions that can be expressed as 1.0, so it goes without saying that they can be easily used in the present invention as long as circuit implementation is possible.

As a result, when synthesizing an arbitrary musical sound waveform, a musical sound waveform generator using a Walsh function that can display 0 becomes a simpler device than a musical sound waveform generator using trigonometric functions. .

Next, the principle of the musical waveform generator according to the present invention will be described.

First, by using a Walsh function generator, Wa up to the nth order is
Generate l sh function Wal(i).

This Walsh function Wal(i) and the Walsh coefficient ai set to a required value in advance are expressed as
It utilizes the principle that a tone waveform is generated by multiplying by an alsh coefficient multiplier and adding the resulting values by an adder.

To be more specific, first, the Walsh function generator generates Wa
l Sh functions are output in parallel from 0th order to (N-1)th order.

FIG. 2 shows the output waveforms of the Walsh functions up to the 15th order.

This parallel output of the O-th to (N-1)th Wa 1
The sh function is then converted into a time-divided serial signal by a multiplexer or the like and output.

At the same time, the Walsh coefficient ai stored in the storage circuit, which has been set to a required value in advance, is read out in synchronization with the output signal of the multiplexer, etc., and these are multiplied together by the Walsh coefficient multiplier, and in the P calculation period aIW
Obtain alp(i).

Thereafter, the output of the Walsh coefficient multiplier is converted into ai XWalp(
i), and as a result, the amplitude F (J)) of the musical sound waveform in the calculation interval P is expressed as follows.

Here, P represents a calculation interval, and P varies from 1 to N.

An example of this calculation is shown in Table 1.
The time chart is shown in the figure.

Next, the amplitude value calculated in each calculation interval P is once latched by a latch circuit, and during that time, the output from the latch circuit is written to a predetermined address of a write-readable waveform synthesis memory.

Thereafter, one cycle of the waveform is written into the waveform synthesis memory in the same manner.

Frequency f of KEY after completion of writing to waveform synthesis memory
The musical tone waveform is read out from the waveform synthesis memory at a speed Nfo corresponding to , and the musical tone waveform is converted into an analog signal by the digital-to-analog converter D/A.

The technical content of the present invention will be explained in detail below based on embodiment drawings and waveform diagrams.

FIG. 4 is a block diagram illustrating an embodiment of a musical waveform generator for an electronic musical instrument according to the present invention.

In the figure, 1 is a clock pulse generator, 2 is a control pulse generation circuit, 3 is a Walsh function generator, 4 is a selector/counter, 5 is a data selector, 6 is a multiplexer, 7 is a coefficient counter, 8 is a coefficient decoder, 9 is Wal
sh coefficient memory, 10 is Walah coefficient multiplier, 11
is an accumulator, 12 is a latch circuit, 13 is a write counter, 14 is a write decoder, 15 is a read counter,
16 is a readout decoder, 17 is a waveform synthesis memory, 18
is a D/A converter, 19 is a clock pulse generator, and terminal Y
is an input terminal for a write command by a tablet drawbar or the like, and terminal U is an output terminal.

In the above connection configuration, the clock pulse generator 1 generates an fcHz clock signal for generating musical waveforms.
h is multiplied by the Walsh coefficient al from the coefficient memory 9.

That is, the coefficient counter 7 is driven by the output pulse Me from the control pulse generator 2, and its coefficient value is decoded by the coefficient decoder 8 and stored in the Walsh coefficient memory 9, which has been set in advance according to the musical waveform, in a time-sharing manner.
It is read out in synchronization with the alsh function and multiplied by the Walsh coefficient multiplier 10.

The circuit example shown in Fig. 7 is a Wal sh function and a Wal sh function.
This is a detailed circuit of the Walsh coefficient multiplier 10 that multiplies the coefficients.

The Walsh coefficient multiplier 10 shown in FIG.
Since the sh function is simply composed of binary values of 1.0, its multiplication ai−Walp(i) is Walp(i
) is 1 and aiSwalp(i) is 0, it is 0, and can be constructed simply by a group of AND circuits as shown in FIG.

Therefore, multiplication by the Walsh function can be performed very easily.

Walsh coefficient multiplier 10 output ai-Walp
(i) is the cumulative command pulse A from the control pulse generator 2
ce is accumulated in the accumulator 11.

In this example, the product up to the 15th order, Σ ai−Wa
lp(i)1=0 is calculated.

When the calculation of Σai-Walp(i)l==0 is completed up to the 15th order, this output is input to the next latch circuit 12, latched by the latch command pulse Lc, and the Σai -Walp+1(i) is completed and latched until a new 1=Q latch command pulse Lc is applied.

During this time, when the accumulated value of the accumulator 11 is latched in the latch circuit 12, the accumulated value is cleared by the accumulated value clear command pulse Acr from the control pulse generator 2 to the accumulator 11, and the contents of the accumulator 11 are cleared. becomes zero and prepares for the accumulation of the next calculation interval P+1.

Subsequent calculations are performed sequentially using the same method.

The calculation process described above can be better understood by referring to the time chart shown in FIG. 5B.

The output of the latch circuit 12 is sent to a writeable and readable memory, that is, a waveform synthesis memory 1T.

The Y terminal shown in FIG. 4 (details will be described later) has an H terminal for writing and an L terminal for continuous output (none of which are shown).
These objectives can be achieved by operating the H and L terminals.

In the case of writing, if you turn it to the H terminal side, the waveform write pulse R from the control pulse generator 2 will be sent to a predetermined address.
The signals are sequentially written into the waveform synthesis memory IJ 17 via the write counter 13 and write decoder 14 controlled by w, and the writing of the waveform-period is completed.

In the case of reading, when the terminal is set to L, the waveform synthesis memory 17 becomes readable.

Then, F(1),
F(2) .

A tufflet with a different tone is connected to the write command input terminal Y.
Or when a command such as a drawbar is given, the waveform synthesis memory 1
7 writes information for different consonant tones and tone quality according to the command given to the write command input terminal Y, and this information is
It becomes possible to read out again by the above-mentioned means.

According to the musical sound waveform generation device for an electronic musical instrument according to the present invention, as described in detail above, an arbitrary musical sound waveform can be obtained by using the Walsh function suitable for the circuit most suitable for digital signal processing. It has the advantage that the overall structure is very simple and can be highly integrated, and it has a remarkable effect when used in electronic musical instruments that require complex musical sound waveforms.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram of an orthogonal function for explaining the principle of the musical sound waveform generator for an electronic musical instrument according to the present invention, and FIGS.
The figure shows an example of the Walsh function used in the musical sound waveform generator for an electronic musical instrument according to the present invention, and its time chart. FIG. 4 shows a block diagram of an embodiment of the present invention. 5, 6, and 7 are detailed circuit diagrams of a control pulse generation circuit, a Walsh function generator, and a Walsh coefficient multiplier used in the musical sound waveform generator for an electronic musical instrument according to the present invention. In FIG. 4, 1... clock pulse generator;
2...Control pulse generation circuit, 3...W
alsh function generator, 4... Selector counter, 5... Data selector, 6...
Multiplexer, 7...Coefficient counter, 8...
... Coefficient decoder, 9 ... Walsh coefficient memory, 10 ... Walsh coefficient multiplier, 11
...Accumulator, 12...Latch circuit, 1
3...Write counter, 14...Write decoder, 15...Read counter,
16... Read decoder, 17...
Waveform synthesis memory, 18...D/A converter, 19
......Key clock pulse generator.

Claims (1)

[Scope of Claims] 1. In a musical tone generating device that calculates the amplitude value of each sampling point, temporarily stores the result, and reads out the content, 2. an orthogonal function generator that generates a value orthogonal function system; a multiplexer that synchronizes with the clock pulse and sequentially selects orthogonal functions of a predetermined order from the orthogonal function system to a digital multiplier; do,
A memory device that stores a plurality of types of coefficients to be multiplied as digital quantities and supplies the coefficients selected according to the musical sound waveform to be generated to the digital multiplier in synchronization with the multiplexer; A digital multiplier that sequentially digitally multiplies a function and its corresponding coefficient; an accumulator that accumulates the digital multiplication results; a waveform synthesis memory that temporarily stores the accumulation results; An electronic musical instrument characterized by comprising a readout device that reads out data using clock pulses at a speed corresponding to waveform key presses, and a digital-to-analog converter that converts the read out composite waveform from digital to analog to generate a musical sound waveform. Musical sound waveform generator.