JPH0582597B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention generates musical tone signals in a time-divisional manner in a plurality of channels, and synchronizes the pitch and sampling frequency of the musical tone signals generated in each channel (harmonically). The present invention relates to a musical tone signal generating device which performs the following.

[Conventional technology]

In digitally processed electronic musical instruments, musical sound waveforms are synthesized by sampling musical sound waveform amplitudes at regular sampling intervals. Conventionally, the following two methods of musical sound synthesis using sampling have been used.
was being implemented. One method is to always sample at a constant sampling frequency regardless of the frequency of the musical tone to be synthesized, and the other is to synchronize the sampling frequency to the frequency of the musical tone to be synthesized. In the former case, the frequency of the musical tone and the sampling frequency are generally in a non-integer ratio, and as is clear from the sampling theorem, anharmonic aliasing noise occurs in the musical tone frequency. In the latter case, the musical tone frequency (pitch)
Since the sampling frequency harmonizes with the aliasing frequency, the component generated by folding harmonizes with the musical tone frequency and does not become noise.

Japanese Unexamined Patent Publication No. 171395/1984 discloses a technique in which the pitch and sampling frequency of the musical tone signals generated in each channel are synchronized as described above when musical tone signals are generated in a time-divisional manner in a plurality of channels. has been done. There, a note clock pulse having a frequency corresponding to the note name of the musical note to be generated in each channel is obtained by frequency-dividing a common master clock pulse.
The note clock pulses of each channel are time-division multiplexed according to the time-division timing formed based on this master clock pulse, and the note clock pulses are responded to based on the time-division multiplexed note clock pulses. Musical tone signals having frequencies are generated in a time-division manner for each channel. Both the note clock pulse and the time division channel timing are synchronized to the master clock pulse, and therefore the pitch and sampling frequency of the musical tone signal set based on the note clock pulse are synchronized.

[Problem that the invention seeks to solve]

However, in the conventional technology described above, note clock pulses are obtained by frequency-dividing the master clock pulse, so the accuracy of pitch synchronization is determined by the frequency of the master clock pulse. In order to increase the frequency, the master clock frequency must be made very high, and as a result, the frequency division wave becomes large, and the scale of the frequency division circuit increases accordingly. In addition, the number of master clock pulses per period of note clock pulses, that is, the frequency division number, cannot be made uniform, and by appropriately combining the frequency division numbers N and N+1 to perform frequency division, the desired overall result can be achieved. Since a note clock pulse having a certain frequency is obtained, the sampling time of the musical tone signal obtained based on the note clock pulse is not uniform, resulting in harmonic distortion.

This invention was made in view of the above points,
To simplify the configuration of a musical tone generation circuit by time-divisionally generating musical tone signals in a plurality of channels, and to solve the problem of aliasing noise by synchronizing the pitch and sampling frequency of musical tone signals generated in each channel. In this case, it is an object of the present invention to provide a musical tone signal generating apparatus which solves the various problems mentioned above caused by obtaining a note clock pulse by frequency division of a master clock pulse.

[Means for solving problems]

In order to solve the above problems, the musical tone signal generating device of the present invention has an independent variable clock oscillation source for each channel, and has a frequency corresponding to at least the note name of the musical tone to be generated in each channel. The present invention is characterized by comprising a clock pulse generating means for independently generating clock pulses for each channel by the variable clock oscillation source.

A musical tone signal generating device according to a second aspect of the invention includes a plurality of clock oscillators each independently generating a clock pulse corresponding to each note name within at least one octave, and a plurality of clock oscillators each independently generating a clock pulse corresponding to each note name within at least one octave; The present invention is characterized by comprising a selection means for selecting the clock pulse and supplying it to each channel.

The clock pulses of each channel supplied from the clock pulse generating means or selecting means are time-division multiplexed between channels by the time-division multiplexing means. A musical tone generating means for time-divisionally generating a musical tone signal having a pitch related to the frequency of the clock pulse based on the clock pulse of each time-division multiplexed channel; means for canceling the time division state of the musical tone signals of the channels and supplying musical tone signals in parallel for each channel; and means for synchronizing the musical tone signals parallelized for each channel with the clock pulses corresponding to each channel. Pitch synchronization means for sampling is provided.

[Effect]

In the clock pulse generation means, a variable clock oscillation source is provided independently for each channel.
A clock pulse having a frequency corresponding to at least the note name of the musical tone to be generated in each channel is generated independently for each channel. No frequency division of the master clock pulse is used here, and the clock pulses corresponding to at least the names of the musical tones generated in each channel are generated completely independently of the clock pulses generated in the other channels. Therefore, the resolution (accuracy of the pulse period) of the generated clock pulses is not limited by the frequency of the master clock pulse at all, and the periodicity of the generated clock pulses is perfectly synchronized with the pitch of the musical tone to be generated at equal time intervals. clock pulses can be generated. Therefore, problems such as harmonic distortion do not occur at all. The same is true when using multiple clock oscillators corresponding to each note name, and because the method of dividing the master clock pulse is not adopted, the cycle is at equal time intervals completely synchronized with the pitch of the musical note to be generated. clock pulses can be generated.

〔Example〕

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

In FIG. 1, a keyboard 10 is equipped with a plurality of keys for specifying the pitch of musical tones to be generated.
The key press detection circuit 11 detects key presses and key releases on the keyboard 10, and provides a signal corresponding to the detected key presses and key releases to the sound generation assignment circuit 12. The sound generation assignment circuit 12 is for allocating the sound of a musical sound corresponding to a pressed key to one of a plurality of musical sound generation channels, and generates a key code indicating the key assigned to that channel at the time division timing corresponding to each channel. It outputs a key-on signal KON indicating whether or not the KC and the key press are connected.

The pitch synchronization clock pulse generation circuit 13 receives the key code KC given from the sound generation assignment circuit 12.
Based on this, a clock pulse having a frequency corresponding to the pitch of the musical tone to be generated in each channel is generated independently for each channel. This pitch synchronized clock pulse generation circuit 13 includes a key code pitch voltage conversion circuit 14 that generates a pitch voltage corresponding to the pitch of the key indicated by the input key code KC, and a key code pitch voltage conversion circuit 14 that generates a pitch voltage corresponding to the pitch of the key indicated by the key code KC. Sample and hold circuits 15-1 to 15-12 for sampling and holding the voltage for each channel, and a voltage controlled oscillator (VCO) provided for each channel to which the sampled and held pitch voltage is input to the control input. 16-1 to 16-12.

As an example, the number of channels is 12, and the sample and hold circuit 15-1 corresponds to each channel.
The sampling control inputs 15-12 are supplied with a channel timing signal CH1 which becomes a signal "1" corresponding to the time division time slot of each channel.
~CH12 is given. Thereby, the tone pitch voltage of each channel output in a time-divisional manner from the key code tone pitch voltage conversion circuit 14 is transferred to the sample hold circuits 15-1 to 15- corresponding to that channel.
12 and held. The voltage controlled oscillators 16-1 to 16-12 independently generate clock pulses having frequencies corresponding to the pitch voltages input thereto.

The output pulses of the voltage controlled oscillators 16-1 to 16-12 have a duty of 50%, for example, and the differentiating circuits 17-1 to 17-12 differentiate the rising edges of the pulses to generate pulses corresponding to the system clock pulse φ. Adjust the width. A clock pulse (hereinafter referred to as a note clock pulse) corresponding to the pitch of the musical note to be generated in each channel obtained in this way.
(referred to as NC1-NC12) is the time division control circuit 18
given to.

The time division control circuit 18 receives note clock pulses NC1 to NC of each channel input in parallel.
12 as channel timing signal CH1~CH1
2, time division multiplexing is performed. An example of the time division control circuit 18 is shown in FIG. 12 RS flip-flops 19-1 to 1
Note clock pulses NC1 to NC12 of each channel are input to set inputs S 9-12, respectively. The outputs Q of the flip-flops 19-1 to 19-12 and the channel timing signals CH1 to CH12 are input to the AND circuits 20-1 to 20-12, respectively, and the outputs thereof are multiplexed by the OR circuit 21 and guided to the line 22. At the same time, they are returned to the reset inputs R of the corresponding flip-flops 19-1 to 19-12. Also, flip-flop 1
The outputs Q of 9-1 to 19-12 are output as pitch synchronization pulses PSP1 to PSP12, and are applied to latch circuits 24-1 to 24-12 in FIG.
It is assumed that the flip-flops 19-1 to 19-12 are set at the rising edge of the signal at the set input S, and reset at the falling edge of the signal at the reset input R. FIG. 3 shows an example of input/output signals of each part in FIG. 2. As is clear from the figure, the key note clock pulses NC1 to NC12 assigned to each channel are asynchronous to the channel timing, and the flip-flops 19-1 to 19-12 are set at the rising edge of these pulses NC1 to NC12. Then, the corresponding AND circuits 20-1 and 20-2
After that, pulses are output from the AND circuits 20-1 to 20-12 in response to the first channel timing signals CH1 to CH12, and the flip-flops 19-1 to 19- are activated at the falling edge of this output pulse. Reset 12. Then, the channel timing signals CH1~NC12 will be generated at the same frequency as the note clock pulses NC1~NC12.
A new note clock pulse synchronized with CH12 is obtained from each AND circuit 20-1 to 20-12. In this way, a note clock pulse corresponding to the musical tone frequency of the key assigned to each channel (an integral multiple thereof) is outputted to the line 22 in accordance with the time division timing of the corresponding channel.

Returning to FIG. 1, the note clock pulses of each channel time-division multiplexed by the time-division control circuit 18 are input to the tone generation circuit 25. The musical tone generation circuit 25 time-divisionally generates a musical tone signal having a pitch related to the frequency of the clock pulse on a time-division multiplexed basis for each channel. For example, it includes an address generation circuit 25a, which counts the clock pulses of each channel in a time-division manner to generate an address signal, and generates a musical tone signal in each channel in a time-division manner according to this address signal. do. Any musical tone generation method may be used in this musical tone generation circuit 25. For example, a method in which musical waveform amplitude values for each sample point are stored in a waveform memory and read out using an address signal, a harmonic synthesis method, a frequency modulation calculation method, or a method disclosed in Japanese Patent Application No. 59-2667. Any method can be used, such as the method shown in No. 1, in which a musical waveform signal is generated by switching a plurality of segment waveforms while interpolating them over time. In addition, in the case of the waveform memory read method, the waveform stored in the memory is not limited to one cycle waveform, but also 1/2
There may be a periodic waveform, an appropriate multi-period waveform, or a complete waveform from the start to the end of sound generation.

The musical tone signals of each channel output from the musical tone generating circuit 25 in a time-divisional manner are transmitted to latch circuits 23-1 to 23-2 provided in parallel corresponding to each channel.
3-12 data inputs. The latch control input L of each latch circuit 23-1 to 23-12 is supplied with a corresponding channel timing signal CH.
1 to CH12 are given. As a result, in the time-division time slot of each channel, the latch circuits 23-1 to 23-corresponding to that channel are
12, the musical tone signal of that channel is latched. In this way, the time-sharing state of the musical tone signals of each channel is released, and musical tone signals are supplied in parallel to each channel.

The outputs of the latch circuits 23-1 to 23-12 are output to the latch circuits 24-1 to 24-12 for pitch synchronization.
is input. Each latch circuit 24-1 to 24-
A time division control circuit 18 is connected to the latch control input L of 12.
Pitch synchronization pulses PSP1 to PSP1 output from
2 is given. Pitch synchronization pulse PSP1~PSP
12 is a pulse synchronized with the frequency of the musical tone assigned to each channel, and by latching (sampling) the musical tone signal according to this pulse, aharmonic clock components generated by channel time division processing are removed. I try to do that. The output of each latch circuit 24-1 to 24-12 is sent to an adder 26.
After being summed, the signal is converted into an analog signal by a digital/analog converter 27 and sent to a sound system 28.

The portion surrounded by the one-dot chain line 29 in FIG.
4 and 5 show examples of changes to the portions (including portions 24-12 to 24-12).

In the example of FIGS. 4 and 5, the musical tone generation circuit 25
The digital/analog converter 30 converts the musical tone signal given from the digital/analog converter 30 into an analog signal to obtain a time-division multiplexed analog musical tone signal. I am trying to synchronize. The time division release circuit 31 receives the channel timing signal CH1.
An analog signal sample and hold circuit consisting of an analog gate controlled by CH12 and a capacitor for storing analog signals is provided in parallel for each channel.

The pitch synchronization circuit 32 shown in FIG. These are provided in parallel for each channel. Time division release circuit 3
The musical tone signals of each channel stored in the capacitors corresponding to each channel in pitch synchronization circuit 32 are converted into pitch synchronization pulses PSP1 to PSP1.
It is sampled by PSP 12 and stored in a capacitor. The musical tone signals of each channel thus stored in the capacitor at sampling intervals synchronized with the pitch are applied to an adder 33 and summed.

FIG. 5 shows an example in which the data representation of the musical tone signal generated from the musical tone generating circuit 25 is based on the differential pulse code modulation (DPCM) method. The part corresponding to the adder 33 in FIG.
Accumulating DPCM musical tone signals
It is replaced with an integrator 35 for converting into a PCM tone signal and summing the tone signals of each channel. The pitch synchronization circuit 34 consists of analog gates for each channel controlled by pitch synchronization pulses PSP1 to PSP12, and the DPCM musical tone signal sampled in synchronization with pitch by the pitch synchronization pulses PSP1 to PSP12 is It is input to an integrator 35 where it is stored cumulatively.

In FIGS. 4 and 5, the digital/analog converter 30 performs D/A conversion on the musical tone signal for each tone (one channel), so like the digital/analog converter 27 in FIG. The number of bits is smaller than when the total musical tone signal is D/A converted. In particular, in the case of FIG. 5, since the musical tone signal is expressed using the DPCM method, the number of bits can be even smaller.

In the case of the DPCM method, the time division cancellation of the musical tone signal of each channel is performed while keeping the digital signal (for example, the latch circuits 23-1 to 23 in Fig. 1).
-12), this may be sampled and accumulated using pitch synchronization pulses PSP1 to PSP12, and then digital/analog conversion may be performed.

In each of the above embodiments, the pitch synchronization pulses PSP1 to PSP12 generated from the time division control circuit 18 are used for the pitch synchronization operation, but note clock pulses NC1 to NC12 are used instead. Good too.

Further, a differentiating circuit 17- provided on the output side of the voltage controlled oscillators 16-1 to 16-12 in FIG.
1 to 17-12 can also be omitted.

In the embodiment shown in FIG. 1, the key code tone high voltage conversion circuit 14 generates a tone pitch voltage that takes into consideration the octave of the musical tone to be generated.
However, the present invention is not limited to this, and a pitch voltage corresponding only to the note name may be generated without considering the octave. In that case, the voltage controlled oscillators 16-1 to 1
Since the frequency of the clock pulse outputted from 6-12 does not take into account the octave of the musical tone to be generated, the frequency of this clock pulse is divided according to the octave, or the address generation circuit 25
It is necessary to perform octave control such as shifting the address signal generated from a according to the octave.

FIG. 6 shows a modification of the pitch synchronized clock pulse generation circuit 13 in FIG. 1
Note clock oscillators 36C to 36B are provided independently corresponding to each note name C to B in the octave, and a clock pulse having a frequency corresponding to each note name generated from each note clock oscillator 36C to 36B is sent to a selector 37. is input. The selector 37 selects note clock oscillators 36C to 36B corresponding to the pitch of musical tones to be generated in each channel.
The output clock pulses are selected and supplied in parallel to each channel. As a selection control signal for the selector 37, note code portions of the key codes KC1 to KC12 of each channel latched by the latch circuit 38 are used.

The latch circuit 38 is connected to the sound generation assignment circuit 12 (first
The key code KC of each channel given in a time-sharing manner from the channel timing signal CH1
-CH12, each channel is latched, and key codes KC1 to KC12 of musical tones (pressed keys) assigned to each channel are output in parallel. Among these key codes KC1 to KC12, a note code portion indicating a note name within one octave is input to the selector 37. The selector 37 selects the clock pulse of the note name corresponding to the note code, and outputs it to lines 39-1 to 39-12 corresponding to each channel. The clock pulses of each channel thus selected are input to octave frequency divider circuits 40-1 to 40-12, and are frequency-divided according to the octave range of musical tones to be generated in each channel. Octave frequency divider circuits 40-1 to 40
The key codes KC1 to KC1 of each channel latched in the latch circuit 38 are input to the -12 frequency division control input.
The octave code part of KC12 is given.

The clock pulse of each channel divided into octaves is sent to a PLL (phase lock loop) circuit 41.
-1 to 41-12. The PLL circuits 41-1 to 41-12 are used to modulate clock pulses corresponding to the tone pitches of each channel using modulation signals such as vibrato.
The clock pulses of each channel output from the PLL circuits 41-1 to 41-12 are sent to the differentiating circuit 41.
-1 to 42-12. Differential circuit 42
-1 to 42-12 are the differential circuit 17-1 in FIG.
17-12, and their outputs are given to the time division control circuit 18 (FIG. 1) as note clock pulses NC1 to NC12.

In FIG. 6, octave frequency dividing circuit 40-1
40-12 may be omitted, and the address signal generated from the address generation circuit 25a in the tone generation circuit 25 (FIG. 1) may be shifted in accordance with the octave code. Furthermore, the note clock oscillators 36C to 36B may be provided not only in correspondence with the 12 note names within one octave, but also in correspondence with note names in a plurality of octaves.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to simplify the circuit configuration by time-divisionally generating musical tone signals in a plurality of channels, and in this case, the pitch and sampling frequency of the musical tone signals generated in each channel can be reduced. Since it is synchronized, the problem of aliasing noise can be solved.
Furthermore, when generating clock pulses that are synchronized with the pitch of musical tones to be generated, the clock pulses are generated independently for each tone to be generated without using a frequency division method, so that the desired pitch can be achieved. It is possible to obtain clock pulses having periods at equal time intervals that are completely synchronized with , and thereby the one sampling time in the obtained musical tone signal is uniform, and harmonic distortion can be prevented from occurring.

[Brief explanation of the drawing]

FIG. 1 is an overall block diagram of an electronic musical instrument showing one embodiment of the present invention, FIG. 2 is a block diagram showing an example of the time division control circuit in FIG. 1, and FIG.
A timing chart showing an example of the signals in each part of the figure.
4 and 5 are block diagrams showing modified examples of the circuit parts for time division release and pitch synchronization in FIG. 1, respectively, and FIG. 6 shows another embodiment of the pitch synchronization clock pulse generation circuit in FIG. 1. FIG. 12... Sound generation assignment circuit, 13... Pitch synchronous clock pulse generation circuit, 14... Key code tone high voltage conversion circuit, 15-1 to 15-12... Sample hold circuit, 16-1 to 16-12... Voltage controlled oscillator, 17 -1 to 17-12, 42-1 to 42-12...Differential circuit, 18...Time division control circuit, 23-1 to 23-12...Latch circuit for time division release, 24-1 to 24-12...Pitch synchronization latch circuit for use, 25... musical tone generation circuit, 31... time division release circuit, 32, 34... pitch synchronization circuit, 36C
~36B... Note clock oscillator, 37... Selector.

Claims (1)

[Claims] 1. Each channel has an independent variable clock oscillation source, and a clock pulse having a frequency corresponding to at least the note name of the musical tone to be generated in each channel is transmitted to each channel by the variable clock oscillation source. a means for time-division multiplexing the clock pulses of each channel generated from the clock pulse generation means; and a means for time-division multiplexing the clock pulses of each channel generated by the clock pulse generation means; musical tone generating means for time-divisionally generating a musical tone signal having a pitch corresponding to each channel; A musical tone signal generating device comprising means for supplying a musical tone signal to a plurality of channels, and pitch synchronizing means for sampling the parallelized musical tone signals for each channel in synchronization with the clock pulse corresponding to each channel. 2. The clock pulse generation means includes a plurality of variable oscillators that are independently provided for each channel as the variable clock oscillation source and whose oscillation frequency can be controlled, and each of the variable 2. The musical tone signal generating apparatus according to claim 1, further comprising control signal supply means for applying a control signal to an oscillator, thereby causing the variable oscillator to generate a clock pulse having a frequency corresponding to the pitch. 3. A plurality of clock oscillators that are provided independently corresponding to each note name within at least one octave and that independently generate clock pulses having frequencies corresponding to each note name, and a plurality of clock oscillators that independently generate clock pulses having frequencies corresponding to each note name, and selecting means for selecting the clock pulse corresponding to the note name and supplying it to each channel; means for time-division multiplexing the clock pulse of each channel; and the clock pulse based on the clock pulse of each time-division multiplexed channel. musical tone generating means for time-sharingly generating a musical tone signal having a pitch related to the frequency of each channel; A musical tone signal generating device comprising means for supplying musical tone signals in parallel for each channel, and pitch synchronization means for sampling the parallelized musical tone signals for each channel in synchronization with the clock pulse corresponding to each channel.