JPS60225196A - Waveform generation 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 [Field of Industrial Application] The present invention relates to a waveform generation method for an electronic musical instrument that generates a waveform using a digital circuit in a 1H child musical instrument.

[Conventional technology] In conventional analog music synthesizers,
It has not been possible to use VCF to achieve a resonance effect that causes the amplitude characteristics to peak near the cutoff frequency. In order to achieve a resonance effect like this σ) using a digital circuit, b) When using sine wave additive synthesis, increase the coefficient of the specific overtone (high Av coefficient),
Digital filters (for example, digital low-pass filters) have been demonstrated to have exactly the same function as analog filters.

[Problem to be solved by the invention] In the above-mentioned prior art, according to (a), K that generates overtones satisfying the optical partial pressure requires many 1-ascending channels, and each harmonic There is a problem in that the excavation level must be variably set for each time, and (b) there is a problem in that the circuit scale of the digital filter itself is large and is difficult to implement.

[Purpose j By the way, the present applicant has previously made a proposal to solve such conventional technology (Japanese Patent Application No. 57-2255).
No. 82 "Musical sound generation method for electronic musical instruments"), the present invention is
In connection with the previous proposal, it is an object of the present invention to provide a waveform generation method for a busy electronic musical instrument that can obtain a more varied resonance effect.

[Means for Solving the Problems] That is, the present invention provides an address signal for reading out a waveform, which has a maximum level for a predetermined period in one cycle of the address signal, and maintains the maximum level from the above maximum level during other periods. An envelope signal that changes to the minimum level or from the minimum level to the maximum level is generated, and the output waveform signal is generated by multiplying this envelope pure signal by a waveform signal of multiple cycles generated in the address signal - period. This is in the waveform generation method of electronic musical instruments.

[Embodiment] The present invention will be described in detail below with reference to an embodiment shown in the drawings.

FIG. 1 shows a block circuit of this embodiment, and 1 in the figure is
The keyboard is a keyboard, and signals corresponding to operations of a plurality of keys provided on the keyboard IK are sent to a frequency information generating circuit 2. The frequency information generation circuit 2 outputs frequency information corresponding to the operation key and supplies it to the phase angle calculation circuit 3.

The phase angle calculation circuit 3 accumulates the supplied frequency information at predetermined timings. By doing so, a signal indicating the phase of the waveform that changes successively, that is, an address signal is generated and applied to the N input terminal of the waveform generation circuit 4.

Further, a modulation signal generating circuit 5 generates a modulation signal for changing the content of harmonic components by sequentially changing the shape of the previous output musical instrument waveform from the keyboard 1 in response to key operations.

The modulation signal is applied to the adder circuit 6, where it is added together with a manually input modulation signal whose contents change depending on the player's volume operation, etc., and then applied to the M input terminal of the waveform generation circuit 4.

In the waveform generation circuit 4, from the address signal that is not given from the N input terminal and the modulation signal that is not given from the M input terminal, while the address signal specifies the waveform-period, K specifies an address with a period greater than the waveform-period. A modified address signal is obtained, and using this modified address signal, waveform information is read out from the memory, and as will be described later, this successively outputted waveform information takes the maximum level for a predetermined period in the above address signal period, and
It is multiplied by an envelope signal (also a window function signal) that changes from the maximum level to the minimum level during periods other than fidgeting, and the resulting waveform signal is output from the O output terminal.

The output waveform signal from this O output terminal is supplied to the envelope multiplier circuit 8 together with the envelope control signal output from the envelope control signal generation circuit 7, and after being envelope multiplied, it is sent to the digital/analog converter (DAC) IC. It is sent out and becomes an analog waveform signal.

Note that the envelope control signal generation circuit 7 includes a keyboard 1.
A signal indicating the operation of the key is supplied to generate an envelope control signal having a predetermined shape.

FIG. 2 shows a detailed circuit configuration of the waveform generation circuit 4 of FIG. 1, in which a modulated signal M is input from the M input terminal. .about.MIl is applied to the B input terminal (B. .about.B, , )K of the multiplication circuit 41.

In addition, address signals N0 to N1 input from the N input terminal
1 is the A input y#A(A.

~A,) is applied.

Then, the multiplication circuit 41 outputs the multiplication result, that is, the value obtained by multiplying the signal from the A input terminal (denoted as A) and the signal from the B input terminal (denoted as B) by 2-12, that is, A×B÷ A value of 212 is output.

Then, the output of the lower 8 bits (Q, to Q,) of the calculation result is applied to the waveform memory 42. Note that the multiplication circuit 41
The upper outputs (Q, to Q11) of are not used. The waveform memory 42 stores one period of a cosine wave. That is, the signal that is not applied to the A input terminal (A, ~A,) K of this waveform memory 42 is an address signal (i.e., a modified address signal obtained by modifying the original address signal N, ~N). Become. Note that although this waveform memory 42 stores a cosine wave, it may also store a sine wave or other waveforms, and it does not necessarily have to store one period's worth of waveform information. By processing such as changing or changing the sign of the output waveform signal, the half period of t & shape or h
By simply storing cycle information in memory, information for one cycle of the waveform can be reproduced.

In this case, the waveform memory 42 generates a cosine wave signal whose amplitude value is expressed in 8 bits.

The signal is sent out from the output terminals 0° to O1 and supplied to the B input terminal (B, to E,)K of the multiplication circuit 43. The N input terminal (A, to A,) of this multiplication circuit 43 is supplied with the envelope signal from the envelope signal generation circuit 44.

That is, the envelope source signal generating circuit 44 is supplied with the upper nine pit signals of the above-mentioned I address signals N0 to NII. That is, the most significant bit signal N of this address signal
il is a NAND game in the envelope signal generation circuit 44) 44
- (Commonly supplied to one input terminal of '1 to 44-7, and also to each NAND game) Address signals N, to N10 are supplied to the other input terminals of 44-n to 44-7, respectively. The outputs of the Nant gates 44-0 to 44-7 become envelope signals, which are supplied to the A input terminal of the multiplication circuit 43 as described above.

This multiplier circuit 43 outputs a value obtained by multiplying the σ) signal from the A input terminal (denoted as A) by the signal from the B input terminal (denoted as B) by 2-11, that is, the value of AXB÷211.

Then, the multiplication output is not applied to the output terminal ( ) and is supplied to the envelope multiplication circuit 8 shown in FIG.

Next, FIG. 3 shows the operating state of this embodiment when the modulation signal given from the adder circuit 6 is at the maximum level F l"I" (in hexadecimal notation), and 4 times ta) is: Address signal N supplied to multiplier circuit 4J via N input terminal
This is a hexadecimal representation of the change in (N, ~N, ,), which is determined according to the frequency of the output musical tone, and changes from KO(10 to F'FFF) during one cycle.

Then, from the multiplier circuit 4, an output Q as shown in FIG.
The multiplier circuit 41 generates a modified address signal that changes up to "t".

FIG. 3 (CJ represents a waveform signal addressed by this modified address signal and generated from waveform memory 42, and this output waveform signal is not supplied to multiplier circuit 43. This multiplier circuit 43 trap further The envelope I @ line signal is the third
It is given by changing as shown in figure (d).

That is, the outputs of the Nant gates 44-(1 to 44-7 are at the maximum level F In the latter half of the cycle (period in which the most significant bit of the address signal N, , is 1''), it changes sequentially from the maximum level to the minimum level 00.

Therefore, the output of the multiplier circuit 43 is as shown in FIG. 3(e), in which the waveform signal generated in the waveform-period is level-controlled by the envelope signal and generated.

Figure 4 shows the waveform signal under these conditions ((a) in the same figure).
and the spectrum of that frequency (FIG. 4(b)).

In addition, FIGS. 5(a) and 6(a) show the waveforms when the magnitude of the modulation signal M in FIG. 4 is set to %, and FIG. 5(b), FIG. ) shows the frequency spectrum at that time, and it is understood that the 8th and 4th harmonic components are emphasized.

In the embodiment described above, the envelope IP6 I/M signal generation circuit 44 generates the envelope signal as shown in FIG. Any method that generates an envelope signal that takes the maximum level during the period and changes from the maximum level to the minimum level or from the minimum level to the maximum level during periods other than the fidgeting period may be used.

〔Effect of the invention〕

As described in detail above, according to the present invention, a resonance effect that emphasizes a specific harmonic component can be achieved with a simple circuit configuration, and a waveform with a period greater than the waveform-period obtained by the waveform-period can be realized. The output waveform signal is obtained by multiplying the signal by an envelope signal that takes the maximum level during a predetermined period of the waveform cycle and changes sequentially from the maximum level to the minimum level # or from the minimum level to the maximum level during other periods. In order to obtain this, we must be able to obtain a drum-shaped signal that includes harmonic components specific to this envelope signal.

Also, by changing the modulation signal that determines the number of waveform signals generated in a waveform period over time, the amplitude characteristics may have a peak. It has the advantage that the 1Ij114 wave components can be changed sequentially over time, and a resonance effect similar to that of an analog music synthesizer can also be obtained.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 shows a block circuit of the first embodiment, FIG. 2 shows details of the waveform generation circuit of FIG. 1, and FIG. 3 shows an example of this embodiment. Signal diagrams for explaining the operation, FIGS. 4 to 6, are diagrams showing fluctuating waveform signals and their frequency spectra according to this embodiment. 2... Frequency information generation circuit, 3... Phase angle calculation circuit, 4... Waveform generation circuit, 5... Modulation signal generation circuit,
41.43... Multiplication circuit, 42... Waveform memory, 4
．． 4... Envelope m-line signal generation circuit, 44-o to 44-7.
... Nantes Gate. Patent applicant Casio Keihin, 74ki Co., Ltd.

Claims (1)

[Scope of Claims] Storage means for storing m-waveform information; address signal generation means for generating an address signal for reading out the waveform information stored in the storage means; and modulation signal generation means for generating a modulation signal. means, from the address signal and the modulation signal, while the address signal specifies the address of the waveform-period, a modification address signal that specifies an address of a cycle equal to or greater than the #-shape-period is generated; address signal generating means; successive means for reading out the waveform information from the storage means using the modified address signal generated from the modified address signal generating means; an enclosing line signal generating means for generating an enclosing line signal that maintains a maximum level for a predetermined period in one cycle of the address signal and changes from the maximum level to the minimum level or from the minimum level to the maximum level during other periods; A waveform generation method for an electronic musical instrument comprising a multiplication means for multiplying the waveform information read out by the means and the envelope signal generated by the envelope signal generation means to obtain an output waveform signal. (2) The envelope signal generating means commonly inputs the most significant bit of the address signal to a first input terminal, and inputs address signals of bits lower than the most significant bit to second input terminals, respectively. ``A waveform generation system for an electronic musical instrument according to claim 1, which comprises a plurality of Nant's gates. (3) A waveform generation system for an electronic musical instrument according to claim 1, wherein the modulation signal generation means generates a modulation signal that changes over time. (4) A waveform generation system for an electronic musical instrument according to claim 1 or 3, wherein the modified address signal generation means includes a multiplication circuit that multiplies the address signal and the modulation signal.