JPS5925233B2 - Frequency control device for electronic musical instruments - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a frequency control device for an electronic musical instrument that digitally performs fine tuning and modulation of scale frequencies.

Traditionally, analog music synthesizers
Although fine tuning is attempted by slightly changing the frequency of the voltage controlled oscillator using a very small voltage, sufficient frequency stability cannot be obtained with such a method. In order to solve this problem, the present invention performs fine tuning using a digital method, thereby realizing fine tuning and modulation with extremely high frequency stability. That is,
The present invention includes a high-frequency clock oscillator, a fine pulse oscillator, and a clock processing device, and the clock processing device calculates the frequency or pulse of a fine pulse output from the fine pulse oscillator from a pulse train of a clock signal output from the clock oscillator. By thinning out a predetermined number of pulses according to the width or duty cycle of the pulses, the average frequency of the clock signal is lowered, and by making the frequency or pulse width of the fine-tuning pulse variable, the average frequency can be approximately reduced. The frequency can be changed continuously, and by dividing this average frequency, a desired tone signal frequency can be obtained.

Further, by temporally changing the frequency and pulse width described above, a vibrato effect and a glide effect can be realized. FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows its timing chart.

In FIG. 1, the clock processing device 10 extracts pulses from the pulse train of the tone clock signal TCK output from the clock oscillator 20 in accordance with the low frequency fine-tuning pulse FIN output from the fine-tuning pulse oscillator 30. It operates to lower the frequency Fc of the signal TCK to αFc. In FIG. 1, tone clock signal TCK is applied to the CK terminals of D flip-flops 1 and 2. On the other hand, the fine adjustment pulse FIN is applied to the D terminal of the D flip-flop 1, and appears at the terminal Q after being assimilated into the tone clock signal TCK at the CK terminal. Since the Q output of D flip-flop 1 is applied to the D input of D flip-flop 2, the output Q of D flip-flop 2 is more sensitive to tone clock signal TCK than its input.
The signal is delayed by one pulse, and the polarity is reversed. Therefore, the output of the NAND gate 3 is a negative pulse with a pulse width equal to one cycle of the first tone clock signal TCK pulse after the fine adjustment pulse FIN rises from "07 to 2 pins." The output of the AND gate 4 is obtained by extracting one pulse from the pulse train of the tone clock signal TCK in the negative pulse portion.When the fine adjustment pulse FIN falls, D
After the output Q of flip-flop 1 becomes //O'', D
Since the output Q of the flip-flop 2 becomes ``1'', the output of the AND gate 3 remains ``1/''. Therefore, one pulse is extracted from the pulse train of tone clock signal TCK only at the rising edge of fine adjustment pulse FIN. If the frequency of the fine adjustment pulse FIN is FF, then FF
During one period of 1/FF, pulses Fc/FF of the tone clock signal are generated, and one of them is erased, so that the frequency αFc of the output signal of the clock processing device 10 is
becomes as follows. Therefore, for example, FF=0.
001·Fc, the pitch can be lowered by 0.10t).

For the fine adjustment pulse FIN, a square wave oscillator whose oscillation frequency can be varied may be used. If a voltage-controlled oscillator is used as the generator of the fine adjustment pulse FIN and its frequency is made variable, it becomes possible to apply a vibrato or glide effect.

By applying the αFc pulse to the program converter 40, a signal of a desired scale frequency can be obtained.

FIG. 3 shows another embodiment of the clock processing device 10.
Figure 4 is the timing chart.

In FIG. 3, 5 is a 3-bit counter that is cleared by the fine adjustment pulse FIN and is clocked by the tone clock signal TCK.
It is counted by Three outputs Q of counter 5. , Ql
, Q2 joins NAND gate 6. Therefore, the period of only one clock out of eight clocks, ie, Q. ,Q
An output A in which all of l and Q2 become 0f only during the period of B is applied to one input terminal of the AND gate 7. A tone clock signal TCK is applied to the remaining input terminal. Therefore, when the fine adjustment pulse FIN is "O" and clearing does not work, the tone clock signal TCK is 8.
The pulses B are thinned out one out of every eight, and seven out of eight pulses B are applied to the next stage program converter. On the other hand, the fine adjustment pulse FIN is
When clearing is performed at bit 5, the output of counter 5 is //
0'', the AND gate 7 opens and all tone clock signal pulses pass through. That is, the output frequency of the AND gate 7 becomes (7/8)Fc or Fc.As the fine adjustment pulse FIN, At a constant frequency,
Use a signal that allows you to change the duty cycle. When the duty cycle is β, that is, the interval of “pi” is the ratio of β to the period, the AND gate 7
The average frequency αFc of the output is as follows. That is, when β is changed from O to 1, α becomes 0.875~
It varies by about 12(f) up to 1,0.

For example, if the median value is β = 0.5, α is 0.93
It changes from 0.875 to 1.0 with 75 as the center. That is, it can be changed by -6.67% to +6.67 (f). If the period of the fine adjustment pulse FIN is small, the above +6.
The fine adjustment resolution of 67% becomes smaller and only rough settings can be made, and if the cycle is large, settings can be made in finer units. This will be explained using a specific example. When Fc is 8MHz and the frequency of fine adjustment pulse FIN is 10KHz, 1
There may be 800 tone clock signal pulses during a period. During that cycle, a minimum of 700 and a maximum of 80
The number of pulses can be arbitrarily set between 0. Therefore, the adjustment in the case of 701 and 700 pieces is a case of poor resolution, and the frequency ratio in that case is (700 pieces).
01-700)÷700=0.00143. This corresponds to 0.143%. In the above description, fine adjustment is performed using one type of tone clock signal TCK, but other methods can be implemented based on the same basic principle.

For example, prepare two tone clock signals. The frequencies of these tone clock signals are shifted. Then, one of these two signals is input to the fine adjustment pulse FIN.
is "0" or "P". In this way, a signal with a frequency intermediate between the frequencies of the two signals can be obtained. By changing the duty cycle of the fine adjustment pulse FIN, the output frequency In these fine adjustment methods, if the duty cycle of the fine adjustment pulse FIN is made electrically variable, it becomes possible to apply vibrato or glide effects.

To make the duty cycle electrically variable, create a pulse wave by slicing a triangular wave, sawtooth wave, or sine wave, and then variably determine the slice level using a voltage comparator, etc. . As described above, the present invention
By thinning out a predetermined number of pulses from the pulse train of the clock signal and making the thinning method variable, it is possible to almost continuously fine-tune the musical tone frequency or apply vibrato. .

Therefore, it is difficult to realize a clock oscillator with a high frequency and a variable frequency. However, according to the present invention, a fixed high-frequency oscillator, such as a crystal oscillator, can be used as the clock oscillator, making it easy to ensure frequency stability. Excellent effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a timing chart thereof, FIG. 3 is a block diagram showing another embodiment of the present invention, and FIG. 4 is a timing chart thereof. 10... Clock processing device, 20...
Clock oscillator, 30...fine pulse oscillator,
40...Program converter.

Claims (1)

[Claims] 1. A high-frequency clock oscillator, a fine-tuned pulse oscillator,
and a clock processing device, by thinning out a predetermined number of pulses from the pulse train of the clock signal outputted by the clock oscillator according to the frequency, pulse width, or duty cycle of the fine-tuned pulse outputted by the fine-tuned pulse oscillator, By lowering the average frequency of the clock signal and varying the frequency or pulse width of the fine adjustment pulse, the average frequency can be changed, and by dividing the average frequency, the desired musical tone signal frequency can be adjusted. A frequency control device for electronic musical instruments. 2. In the statement of claim 1, the pulse of the clock signal is changed to 1 at the same time as the fine adjustment pulse rises or falls.
A frequency control device for an electronic musical instrument, characterized in that the frequency control device for an electronic musical instrument is configured to perform main thinning, and the frequency of the fine tuning pulse is made variable. 3. In the statement of claim 1, the clock processing device includes a gate circuit that thins out pulses from a clock signal at a constant rate, and a gate circuit that thins out pulses from a clock signal at a constant rate, and a gate circuit that thins out pulses from a clock signal at a constant rate, and a gate circuit that thins out pulses from the clock signal at a fixed rate according to the duty cycle of the fine pulse. 1. A frequency control device for an electronic musical instrument, comprising: a circuit for outputting one of the clock signals, and the duty cycle of the fine adjustment pulse is made variable. 4. An electronic musical instrument as set forth in claim 1, characterized in that a modulation effect such as a vibrato effect or a glide effect is realized by temporally changing the frequency or pulse width of a fine tuning pulse. Frequency control device.