JPS5854394A - Envelope signal control circuit - 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 The present invention relates to a short axis (envelope) signal control circuit suitable for use in, for example, electronic musical instruments, and in particular, it is capable of digitally processing the signal and controlling the envelope signal by one tit. This relates to the envelope curve control 141 circuit.

In the electronic transmission of conventional analog synthesizers, as shown in Figure @1, the output of the voltage controlled oscillator (vco) (i) and the output of the envelope signal generator (2) are connected to a voltage controlled amplifier (VCA). ) 13) to obtain an enveloped VHFC output signal from this voltage controlled amplifier (3). That is, when a rectangular pulse is supplied to the envelope signal generator (2) as a key switch (keyboard) or the like is pressed, the desired musical tone will start with 222244 as shown in Figure 2. , so-called A, which falls at decay time D, holds the sustain level S for a predetermined time, and then releases at Vy-s time R.
Envelope No. 16e having DSB characteristics is supplied from the above-mentioned envelope signal generator (2) to the voltage controlled amplifier (3).

By this voltage controlled amplifier (3), the output signal from the voltage controlled oscillator (1) is amplified in an analog multiplicative manner according to the voltage change of the envelope signal e. Bao&! Since the signal eO) curve part has an exponential function waveform, it is considered to be the most natural fTR# mode, but in the conventional envelope IIS* signal generator (2), a time constant 1g circuit consisting of a condenser and a resistor is used. Since the above-mentioned envelope fusion signal e is obtained by analog means by utilizing the photodischarge characteristics, it is difficult to fully digitize the circuit, and multi-channel time-division processing is also difficult and the configuration is complicated. There are many shortcomings such as:

Mamour, Envelope - The approximate envelope mI is formed by constructing the Tsukuji Generator (2) from a digital circuit and approximating it with a straight line as shown in Figure 6.
We also propose a system in which the output signal from the voltage controlled oscillator (1) is added with an input signal based on the IM signal C'. However, in this case, there is a drawback that the auditory sensation remains unnatural, and there is also the disadvantage that the digital multiplier is a public expense, which increases the cost.

The present invention was invented in view of the above-mentioned circumstances, and includes a signal generating means for outputting a frequency tr@it, and a frequency information signal that is exponentially generated based on the frequency information signal supplied from the signal generating means. exponential function waveform generation means for generating an attenuating signal; pulse generation means for outputting a pulse signal whose pulse width is increased by Rv4 as the frequency ridge signal is supplied; and the exponential function waveform generation means. The signal from Wa
The present invention relates to an envelope signal control circuit similar to that for gating with a pulse signal from the pulse generation stage.

If such a configuration is adopted, it is possible to easily perform time-division multiplexing when circuits can be digitized and integrated into ICs, and the auditory sense can be easily performed without using complicated and expensive multipliers. 1. You can obtain the most natural-sounding exponential function envelope.

An embodiment of the present invention will be described below with reference to FIGS. 4 to 7.

Ω Figure 4 schematically shows the configuration of the control circuit for control circuit 1g used in the time-division multiplex system.0 In Figure 4, QI has multiple key switches arranged. When the key switch of this key operation section Ql is pressed, number 15 corresponding to the pressed 9 key switch is output from the key operation section Q1. And this signal is +#1~41+N by key assigner -aυni? v
The signal is assigned to one of the Y channels (see FIG. 5) that is not being used at this time and is supplied to the control circuit Q21. Digital 11 from this control circuit a! !
A control signal corresponding to the pressed key switch is supplied to the signal generation circuit a3 as a frequency information (pitch information) signal, and an encoded digital signal is output from the digital waveform generation circuit a1 based on the above-mentioned control signal. be done.

This digital signal is converted into an analog signal by the D-me converter I, and the analog signal of the frequency corresponding to the pressed key switch is supplied to the sampling circuit 4 as a maa information signal through the rono filter ttS+. Next, the amplitude value of this analog No. 11! is sampled at a predetermined period by a sampling circuit and supplied to a time constant circuit αη.

The above-mentioned time constant circuit is composed of a resistor and a resistor, and the sampling voltage supplied to the time constant circuit aD is discharged at a constant time constant and decays exponentially as shown in Figure 1. The electric energy signal a is supplied to the analog gate αη. Note that for this droplet pressure signal a, if the vertical axis ('-pressure) is y, the horizontal axis (time) is t, and the time constant of the one time constant circuit is τ, then y1 =Cτ.

On the other hand, as the key switch is pressed, a predetermined control signal is supplied from the previously described control circuit 4 to the timing control section a1, and from this timing control section α1, a predetermined timing control is applied to the pulse generation path 1 (toward). A signal is provided. In response to this, the pulse generation circuit first generates a pulse signal b which is continuously modulated over a period of attack time A.
(See @5 Figure ■) is output. The leading edge (rise time) of this pulse signal Cj is synchronized with the switching time of each channel, so that the leading edge (rise time) of this pulse signal S is synchronized with the switching time of each channel.
The terms are evenly spaced. The trailing edge (falling point) of the pulse signal (in the Manaya channel) c2 is gradually moved in the direction indicated by the arrow in #A5, Figure 1ζ, every sampling period. That is, For example, reference 1
Regarding the pulse signal of the channel, as shown in Fig.
1 in the next sampling period)<Russ (the pulse width W2 of the m number b2 becomes wider 9, and similarly) (so that Rouss gradually becomes wider). Furthermore, the signal widths of the other channels are also modulated by /<1 width in the same manner as described above.

The voltage signal a from the time constant path α is applied during the rising period of the pulse signal (e.g., from time 0 to 1, which is gated over T1
As a result, for example, based on the pulse signal b1, the voltage signal a becomes analog goo over the period from time 0 to T1)
Ql is supplied to the low pulse filter t2υ, and the output terminal has an area of 81 indicated by the beveled edge in Figure @6.
A voltage signal A' is obtained which approximately corresponds to . In addition, 81=
1′. 'e-! dt=! (”-?).

Therefore, if the voltage signal a is gated by the pulse signal b+ and supplied to the filter Qυ while the pulse signal is gradually widened every sample period, the output is From terminal (2), a voltage 1i1 rises exponentially as shown by curve A' in Figure 5 (■).
number is obtained. And this voltage grace period or attack time A
This is the output characteristic curve during the period of 〇 Also, during the period of decay time D after the elapse of attack time A, the pulse generation circuit 4 is controlled by the tie-building control section a1, and from this pulse generation circuit (to) is @5
As shown in FIG. 2, the pulse signal d whose pulse width has been modified is output to the analog gate α.

This pulse signal d is at the trailing edge (at the falling edge of the pulse) gl
The sand is synchronized with the channel switching time, and each trailing edge is equally spaced. On the other hand, the leading edge (at the time of pulse rise) gl of the pulse signal d changes every sampling period @Fig.
, and is gradually moved in the direction indicated by the arrow. That is, for example, for the channel/channel pulse signal of 4P1, the pulse width W5 of the pulse signal d2 in the next sampling period becomes narrower than the pulse width W5 of the first pulse signal d1, and the pulse width gradually decreases. Pulse-modulated to narrow. Furthermore, the pulse signals d in the other channels are also affected in the same way as described above so that their respective pulse widths are affected.

When the pulse signal d which has been pulse-smooth modulated in this way is supplied to the f analog gate α barrel, the voltage signal a changes from the rising edge of the pulse signal d (for example, from time 'l'2 to T
gated over the following period). As a result, for example, the voltage signal a is supplied from the analog gate α barrel to the low-pass filter (21) over the period from time T1 to 1' based on the pulse signal d1, and the output terminal (the 5th Figure■
A voltage signal y (see Fig. 7) approximately corresponding to the area S2 of the portion indicated by the beveled edge is obtained. In addition, s2 = engineering T
e-! di ==i (e-?,-!) and 2.

Therefore, if the pulse width of the pulse signal d is gradually narrowed every sample period and the voltage signal is gated by the pulse No. 16 d and supplied to the pulse filter +21, the output terminal cl From !a, a voltage signal that decreases exponentially as shown by curve D' in Figure 5 is obtained.This voltage signal is then given decay time D.
After that, the output characteristic curve from the analog gate a barrel becomes voltage 4 and decay time D.
(The screw pressure level at the end of /J, that is, the sustain level 8ic @ 5, is maintained for a predetermined time as shown by the straight line 8' in Fig. ) Kurusu (I No. d is Analog Goo) (Supplied to 18, as in the case of the decay time D mentioned above, the release time period l as shown in Figure 5 This is reduced from Sustain V Pel S to zero in the form of a tin number function.

As a result, the output terminal c! 3, the voltage rises exponentially during the attack time period and falls exponentially during the decay time D period, and after maintaining the sustain level S for a predetermined period, the voltage rises exponentially during the V release time period. A such that decays exponentially to zero
The envelope rII signal output with the D8B characteristic is obtained by the envelope of the above configuration. The waveform is supplied as an analog human input signal to an analog gate, and the (modulated) signal is gated based on d.Thus, the attack time, decay time, and It is possible to easily obtain an envelope output that changes exponentially, that is, an exponential envelope output that sounds the most natural to the ear.In addition, timing control 5
By digitally controlling tll, it is possible to control the envelope signal, making it easy to integrate the circuit (IC).Moreover, since it can handle time division multiplexing, it is possible to use multi-channel/channel sound source circuits. It is possible to construct a high-performance electronic musical instrument for polyphonic use or for multi-voice use.

Furthermore, conventionally, in order to obtain ADSB characteristics, a multiplier that multiplies the frequency signal from the tortoise suppression oscillator (1) and the envelope signal is required, but in this embodiment, the voltage that wraps the multiplier as described above is 111J# Trivia (3) Since an inexpensive circuit configuration using an analog gate a-barrel is sufficient instead, it becomes possible to significantly reduce the cost of electronic musical instruments.

Although the present invention has been described above with reference to one embodiment, the present invention is not limited to this embodiment, and each machine can be modified based on the technical idea of the present invention.

For example, in this embodiment, a digital signal may be generated and converted, or a frequency information signal consisting of an analog signal may be supplied from the control circuit a3 to the low-pass filter α field.

As described above, the present invention obtains an exponential waveform signal from the exponential waveform signal generation means (e.g., sampling circuit ae and time constant curve a7) based on the frequency information signal, and obtains an exponential waveform signal from the pulse generation means (e.g., timing control By gating the stock number function waveform with a pulse signal that has been subjected to pulse rotation from the section (1) and the pulse generation circuit (4), an exponent@number envelope output that sounds most natural to the ear can be obtained. Therefore, according to the present invention, it is possible to control the envelope curve by digitally controlling the pulse of the gate pulse signal, so that the circuit can be easily integrated into an IC. In addition, since time division multiplexing can be performed, it is possible to configure a single multi-channel sound source.Furthermore, it is possible to perform multiplexing using analog gate means without using a multiplier that is complicated and recommended. Since signal control can be performed, it is possible to simplify the configuration and reduce costs.Therefore, in order to apply the envelope*i'i signal control circuit of the present invention to electronic musical instruments, it is possible to simplify the configuration and reduce costs.
It is possible to obtain an electronic musical instrument that has the same performance as lte voice and is inexpensive.

[Brief explanation of the drawing]

@ Figure 1 is a block diagram schematically showing a conventional envelope signal control (b) path used in electronic musical instruments, and Figure 2 is an envelope signal control path.
FIG. 6 is a waveform diagram showing the AD8R characteristics of the signal, and is a waveform diagram when the envelope signal is monolithically approximated by digital control. Figures 4 to 7 are for explaining one embodiment of the present invention, in which Figure 4 is a block diagram of the envelope signal system, and Figure @5 is a block diagram of the envelope signal of Ren. Time chart for explaining the operation of the control circuit % Figure 6 is a waveform diagram for explaining the waveform of the envelope signal at the attack time, and Figure 7 is the waveform of the envelope signal at the decay time and V rise time. FIG. 2 is a waveform diagram for explaining. In addition, in the code used for 1 meat, 0I...
・・・・・・・・・Key operation section u area・・・・・・・・・・・・
...Control circuit Qe...Sampling circuit -...Time constant circuit αl...
・・・・・・・・・Analog gate 9・・・・・・
・・・・・・Timing control section■・・・・・・・・・・・・
・・Pulse generation circuit (211・・・・・・・・・・・・
Low-pass filter 0 Agent Souvenir Katsu l Pine wood Osamu Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] a signal generating means for outputting frequency information No. 46; an exponential function waveform signal generating means for generating a signal that decays exponentially based on the frequency information No. 1d supplied from the signal generating means; and the frequency change number. Love @1! R number is supplied 4
a pulse generating means for outputting a pulse-modulated pulse signal along with C; and an analog gate child actor for gating the signal from the exponential function waveform signal generating means with the pulse signal from the pulse generating means. An envelope signal control circuit characterized in that each curve is biased by -X.